United States         Office of           Reprint of
             Environmental Protection     Water Program Operations     Department of the Army
             Agency           (WH-595)           EM 1110-2-501
                          Washington, D.C. 20460     September 1978
             	EPA/430/9-79-008	

             Water	
>EPA        Design  of Wastewater
             Treatment  Facilities
             Major Systems

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                         DEPARTMENT  OF THE ARMY             EM 1110-2-501
                      Office  of  the Chief  of Engineers          Part  1  of 3
DAEN-CWE-BU              Washington, D.C.  20314

Engineer Manual                                          29 September  1978
No.  1110-2-501

                         ENGINEERING AND  DESIGN
                Design of Wastewater Treatment Facilities
                              Major Systems

1.   Purpose.  Part One of this  manual provides guidance  for the  selection
of wastewater treatment systems  and processes and criteria for the  design
of wastewater treatment facilities.

2.   Applicability.  The provisions of this manual are applicable to Corps
of Engineers Divisions and Districts concerned with the  planning, design,
and  optimization of new and upgraded wastewater treatment facilities  for
Civil Works, and for  the preparation of documents for wastewater management
programs.

3.   General.  In 1972 the Corps  of Engineers became a full partner, along
with other Federal agencies, in  Urban Area Comprehensive Planning organized
by the state and local governments.  The  Corps of Engineers was given the
authority for studying water problems in urban areas in  addition to its
traditional sanitary  sciences role at recreation sites,  and for providing
information valuable  to state and local governments for making grant
applications.  These governments have the responsibility for relating
urban water problems,  such as flood control, water supply, and wastewater
management to other urban problems, such as neighborhood renewal, recreation,
and  transportation.  This new responsibility emphasizes the need for  in-depth,
and  sound plans and designs for wastewater treatment facilities.  This
manual is intended to provide design and cost criteria on which logical
choices for urban wastewater treatment plants may be made.

FOR THE CHIEF OF ENGINEERS:
f
                                                PETERSON
                                    Colonel, Corps of Engineers
                                    Executive Director, Engineer Staff
                  U.S.  Environmental Protection Agency
                  Region V, Library
                  230  South Dearborn Street
                  Chicago,  Illinois  60604

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U,C.  Environmental Protection /.£-r,:r/

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DAEN-CWE-S
Engineer Manual
No. 1110-2-501
     DEPARTMENT OF THE ARMY
Office of the Chief of Engineers
    Washington, D. C.  20314
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                   29  September 1978
                         Engineering and Design
                DESIGN OF WASTEWATER TREATMENT FACILITIES
                              MAJOR SYSTEMS
                            Table of Contents
               	Subject	
                                             Page
CHAPTER 1.      INTRODUCTION	  1-1
CHAPTER 2.      CHARACTERIZATION OF WASTEWATER FOR URBAN
                  AREAS	  2-1
CHAPTER 3.      DESIGN CONSIDERATIONS	  3-1
CHAPTER 4.      DESIGN AND EVALUATION OF PROCESSES AND
                  SYSTEMS	  4-1
CHAPTER 5-      PHYSICAL UNIT PROCESSES
Section I.      INTRODUCTION	5-1
Section II.     GRIT REMOVAL	5-3
Section III.    SCREENING	5-19
Section IV.'     COMMINUTION	5-29
Section V.      EQUALIZATION	5-33
Section VI.     FLOTATION	5-41
Section VII.    THICKENING jGravity)	5-57
Section VIII.   SEDIMENTATION (Primary Clarifier)	5-6?
Section IX.     SEDIMENTATION (Secondary Clarifier)	5-83
Section X.      FILTRATION	5-93
Section XI.     VACUUM FILTRATION	5-119
Section XII.    CENTRIFUGATION	  5-131
Section XIII.   MICROSCREENING	  5-139
Section XIV.    DRYING BEDS	  5-149

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EM 1110-2-501
Part 1 of 3
 29  Sep  78

Section XV.
Section XVI.
Section XVII.
Section XVIII.
CHAPTER 6.
Section I.
Section II.
Section III.
Section IV.
Section V.
Section VI.
Section VII.
Section VIII.
Section IX.
CHAPTER 7.
Section I.
Section II.
Section III.
Section IV.
Section V.
Section VI.
Section VII.

Section VIII.
Section IX.
Section X.
Section XI.
Subject
POSTAERATION 	 , 	
SLUDGE HAULING AND LANDFILLING 	
MULTIPLE HEARTH INCINERATION 	 -
FLUIDIZED BED INCINERATION 	
CHEMICAL UNIT PROCESS
INTRODUCTION 	
CARBON ADSORPTION 	
CHEMICAL COAGULATION 	
AMMONIA STRIPPING 	
CHLORINATION 	
ION EXCHANGE 	
NEUTRALIZATION 	
RECARBONATION 	
TWO-STAGE LIME TREATMENT 	
BIOLOGICAL UNIT PROCESSES
INTRODUCTION 	
TRICKLING FILTERS 	
PLUG FLOW ACTIVATED SLUDGE 	
COMPLETE MIX ACTIVATED SLUDGE 	
STEP AERATION ACTIVATED SLUDGE 	
EXTENDED AERATION ACTIVATED SLUDGE 	
MODIFIED OR HIGH-RATE AERATION ACTIVATED
SLUDGE 	
CONTACT STABILIZATION ACTIVATED SLUDGE 	
PURE OXYGEN ACTIVATED SLUDGE 	
AERATED AEROBIC LAGOONS 	
AERATED FACULTATIVE LAGOONS 	
Page
- 5-159
- 5-169
- 5-177
- 5-189

6 1
- 6-3
- 6-17
- 6-25
- 6-35
- 6-^3
- 6-55
- 6-61
6 69

- 7-1
- 7-3 ^
- 7-13 "
- .7-37
- 7-69
- 7-95

- 7-129
- 7-151
- 7-171
- 7-205
- 7-223
                                   11

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                              29 Sep  78
                          Subject
Page
Section XII.    OXIDATION DITCH	  7-235
Section XIII.   NITRIFICATION-DENITRIFICATION	  7-253
Section XIV.    AEROBIC DIGESTION	  7-277
Section XV.     ANAEROBIC DIGESTION	  7-291
Section XVI.    STABILIZATION PONDS	  7-307
CHAPTER 8.      COST DATA AND ECONOMIC ANALYSIS
Section I.      INTRODUCTION	  8-1
Section II.     PHYSICAL UNIT PROCESSES	  8-5
Section III.    CHEMICAL UNIT PROCESSES	  8-13
Section IV.     BIOLOGICAL UNIT PROCESSES	  8-17
APPENDIX A.     REFERENCES	  A-l
APPENDIX B.     ABBREVIATIONS	  B-1
APPENDIX C.     CONVERSION FACTORS FOR UNITS OF MEASUREMENT;
                  DISSOLVED-OXYGEN SOLUBILITY DATA; PHYSICAL
                  PROPERTIES OF WATER; CHEMICAL ELEMENTS AND
                  SUBSTANCES; SPECIFIC WEIGHT	  C-l
GLOSSARY        	  Glossary 1
INDEX           	  Index 1
                                  111

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                                                            EM 1110-2-501
                                                              Part  1 of 3
                                                               29 Sep  78

                                CHAPTER 1

                              INTRODUCTION

1-1.  Purpose.  Part One of this manual provides guidance for the selec-
tion of wastewater treatment systems and processes and criteria for the
design of wastewater treatment facilities.

1-2.  Applicability.  The provisions of this manual are applicable  to
Corps of Engineers Districts and Divisions concerned with the planning,
design, and optimization of new and upgraded wastewater treatment facil-
ities for Civil Works, and for the preparation of documents for waste-
water management programs.

1-3.  References.  See Appendix A for a list of selected references.

1-4.  General Considerations.

     a.  In 1972 the Corps of Engineers became a full partner, along with
other Federal agencies, in Urban Area Comprehensive Planning organized
by the state and local governments.  The Corps of Engineers was given
the authority for studying water problems in urban areas in addition to
its traditional sanitary sciences role at recreation sites, and for pro-
viding information valuable to state and local governments for making
grant applications.  These governments have the responsibility for  re-
lating urban water problems, such as flood control, water supply, and
wastewater management to other urban problems, such as neighborhood
renewal, recreation, and transportation.  This new responsibility empha-
sizes the need for in-depth, and sound plans and designs for wastewater
treatment facilities.  This manual is intended to provide design and
cost criteria on which logical choices for urban wastewater treatment
plants may be made.

     b.  The Corps of Engineers executes the Urban Studies Program  in a
manner consistent with two basic principles:

     (1)  The responsibility for, and leadership of, urban area compre-
hensive planning is vested in state and local governments; and

     (2)  Duplication or conflict among Federal, state, regional, and
local agencies participating in urban area comprehensive planning is to
be avoided.
                                 1-1

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EM 1110-2-501
Part  1 of 3
29 Sep 78

    c.  The Corps of Engineers' responsibility for planning, optimizing,
and integrating selected treatment plant designs with other regional
water resource priorities is directed toward meeting the goals set forth
in the 1972 Amendments to the Federal Water Pollution Control Act
(PL 92-500).

    d.  Wastewater composition in urban/regional areas includes wastes
that  are:  (l) domestic in nature; (2) generally domestic with some
industrial; (3) primarily industrial; (4) primarily agricultural runoff;
(5) urban storm water runoff; or (6) combinations of the above.

1-5-  Problems.  Some of the problems associated with designing adequate
wastewater treatment facilities for metropolitan areas are:

    a.  The composition and relative level of enforcement of wastewater
standards and criteria vary substantially from state to state and along
different waterways and may exceed the requirements of PL 92-500.

    b.  Appropriate technical design guidance either has not been avail-
able  or is inadequate for certain systems or subsystems, and, in some
instances, existing guidance may contribute to operational problems.

    c.  Flow rates and composition of discharged waste vary widely.

    d.  Requirements demand aesthetic quality be considered in site se-
lection, design, construction, and operational practices.

    e.  A high degree of treatment is often required (up to and includ-
ing advanced wastewater treatment standards).

    f.  Characterization of raw,  primary, and secondary waste treatment
systems in some areas is generally inadequate to support a comprehensive
planning process for the area.

    g.  Data from recent and current research activities and from spe-
cific design problems in the field have not yet been correlated to yield
the maximum benefit.

1-6.   Use of the Manual.

    a.  This manual is arranged in three parts so that the planner or
designer will have quick access to data for many wastewater treatment
processes both for the design of new treatment facilities and for the
checking and optimization of existing facilities.  Subsequent chapters
                                   1-2

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78

of Part One of this manual include design equations for waste treatment
processes; systems for computing costs and estimating the overall effi-
ciency of selected processes for major waste-water treatment facilities.
Part Two addresses those problems unique to the recreation area planner
and provides characterization and designs for "Small Scale Wastewater
Treatment Systems."  To further aid planners and designers, a computer
aided design program (CAPDET) is available incorporating the design
methodology encompassed by Parts One and Two of this manual plus land
treatment.  This program is currently running on the Waterways Experi-
ment Station GE-600 computer.  The user guide for the CAPDET program is
Part Three of this manual.

    b.  This part of the manual serves to familiarize the designer with
the practical and theoretical aspects of physical, chemical, and bio-
logical processes and process trains for urban-type facilities ranging
from simple to complex systems, including tertiary systems for nutrient
removal.  A table of factors for converting U.  S.  customary units of
measurement to metric (Si) units, a chart containing the physical prop-
erties of water, and a glossary are appended hereto for the convenience
of the user.

    c.  It should be recognized that the effects of scale are severe
limitations when dealing with physical-biologic systems such as those
found in wastewater treatment.  This is especially true when small
facilities are being considered such as those required for very small
communities or intermittent-use systems such as those found at Corps'
recreational sites.  In these cases,.where physical units become very
small and operators are not on the plant site continuously, many of the
more sophisticated unit process designs described in this manual are not
applicable.  The user is referred to Part Two of the manual which deals
with small-scale wastewater management when faced with problems of this
scope.
                                   1-3

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                                                           EM 1110-2-501
                                                             Part  1 of 3
                                                              29 Sep 78

                                CHAPTER 2

             CHARACTERIZATION OF WASTEWATER FOR URBAN AREAS

2-1.  General.   Water usage rates,  wastewater production rates,  and
wastewater characterization data for domestic sewage have been docu-
mented for urban area design.  These rates and qualities are representa-
tive of the "average" city and are  subject to the engineer's knowledge
of the area for their intelligent application.   Needless to say, no table
of statistical values is a good substitute for field data.   However, the
information presented in this chapter will allow the engineer to prepare
a first-look design and obtain rudimentary cost data for the area.   Sub-
sequent iterations in the planning  process demand that these average
values be replaced with site-specific values.

2-2.  Selection of Urban Area Flow Design Parameters.

    a.  Total Waste Flow.

    (l)  One- of the most important  parameters required for the effective
and realistic planning of any community sanitary facility is flow.   Flow
is the major determinant of size, location, and public acceptance of any
plant.  Unfortunately, flow may frequently be the most elusive parameter
to forecast.  Many factors dramatically affect the flow reading of a
waste treatment facility; among these are (a) geographical location,
(b) type of users (e.g., residential, industrial, agricultural,  etc.),
(c) sewer inflow, infiltration, and exfiltration, (d) consumptive uses
(e.g., lawn watering, car washing,  etc.), (e) storm event history, and
(f) precipitation and resulting runoff.

    (2)  Metcalf and Eddy have found that between 60 and 80 percent of
the per capita consumption of water will become sewage.  Based on
studies by the U. S. Public Health Service for the Select Committee on
Natural Water Resources published in I960, the average water consumption
on a national basis was found to be approximately iVf gallons per capita
per day (gpcd).  This therefore represents an average wastewater flow
from 88 to 118 gpcd or about the 100-gpcd figure so frequently reported
in the literature.  It should again be emphasized that this value rep-
resents only an average value which must be used with caution.  An in-
crease of only 1 gpcd in a city the size of Kansas City can amount to
over $500,000 in capital and $150,000/year in operation and maintenance
(O-M) costs.

    b.  Flow Variations.  In addition to the average flow, the designer


                                   2-1

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EM 1110-2-501
Part 1 of 3
29 Sep 78

must be cognizant of the maximum and minimum flows.  The design of many
unit processes is based on a knowledge of peak flows, while the design
of others is based on minimum flows.  Table 2-1 provides some compari-
sons found by Clark and Viessman in their research on domestic flow
fluctuations.  Additional references to flow variations are given in
sections 4-3, 4-4, 4-6, 9-c(l)(2), 9-b, 10-f(2), and Technical Manual
No. 5 - 814-3, "Domestic Wagtewater Treatment."
    c.  Inflow/Infiltration.  The terms "inflow" and "infiltration" are
used to describe flows into the sanitary sewer system from sources other
than normal sewage connections.  Inflow refers to connections of waste-
water to the system which may not be septic in the biologic sense of the
term.  Such connections include roof drains, parking lot drains, miscon-
nected storm water laterals, etc.  Most inflows provide low pollutant
levels with relatively high volume quantities.  This water is exces-
sively expensive to reclaim in the sanitary system and normally is
better disposed of by other means.  Frequently nonstructural solutions
(e.g., sewer ordinances) are required to deal with areas of excessive
inflows.  On the other hand, infiltration refers to the inward seepage
of groundwater into the collection system.  The volume of such infiltra-
tion is a direct function of the length, size, and condition of the col-
lection system as well as the depth of the groundwater.  According to
Environmental Protection Agency (EPA) guidelines, inflow/infiltration
below 1000 gpd per inch diameter of pipe per mile is nonexcessive.
Current EPA procedure is to determine if inflow/infiltration is excessive
to a point where it is more cost-effective to replace and/or rehabilitate
than to continue to transport and treat.

2-3.  .Selection of Urban Area Wastewater Quality.  Like flow, the quality
of raw sewage fluctuates from region to region.  Table 2-2 gives a set
of typical characteristics of domestic sewage representative of most
urban areas.  It must likewise be realized that heavy industrial or
commercial loadings can have a dramatic effect on the values listed.
                                    2-2

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                                         EM 1110-2-501
                                           Part  1 of 3
                                              29  Sep /8
Table 2-1.  Residential Sewage Flows
      as Ratios to the Average
Flow
Maximum daily
Maximum hourly
Minimum daily
Minimum hourly

Ratio
2.25 to 1
3.00 to 1
0.6T to 1
0.33 to 1

Table 2-2. Typical Characteristics of Domestic Sewage
(mg/Jl unless
Parameter
BOD
COD
TOC
pH (units)
Total solids
Suspended, total
Fixed
Volatile
Dissolved, total
Fixed
Volatile
Settleable solids (m£/£)
Total nitrogen (as N)
Free ammonia (as NE~)
Total phosphorus (as P)
Chlorides (as Cl)
Sulfates (as SO, )
Alkalinity (as CaCO,.)
Grease
noted

High
350
800
300
7.5
1200
350
100
250
850
500
350
20
60
30
20
150
kO
350
150
otherwise)
Amount
Average
200
Uoo
200
7.0
700
200
50
150
500
300
200
10
1*0
15
10
100
20
225
100


Low
100
200
100
6.5
Hoo
100
25
75
300
200
100
5
20
10
5
50
10
150
50
                 2-3

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                                                           EM 1110-2-501
                                                             Part  1  of 3
                                                               29 Sep 78

                                CHAPTER 3

                          DESIGN CONSIDERATIONS

3-1.  Design Factors.   Factors that must "be considered in the prepara-
tion of a design of a waste-water treatment facility may be subdivided
into site and system selection factors.

    a.  Site Selection.

     (l)  Distribution of facilities.

     (2)  Topography.

     (3)  Vegetation.

     (U)  Soil type—permeability and chemical composition.

     (5)  Groundwater elevation and location of aquifers.

     (6)  Distance to and condition of bedrock.

     (?)  Proximity to surface vaters.

     (8)  Land availability and cost.

     (9)  Stream water quality designation.

    (10)  Sludge disposal opportunities.

    (ll)  Collection system accessibility.

    (12)  Proximity to human nabitation.

    b.  System Selection.

     (l)  Governing criteria—legal and political.

     (2)  Number and types of facilities to be served.

     (3)  Energy requirements and availability.

     (h)  Capital cost of system.
                                   3-1

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EM 1110-2-501
Part 1 of 3

29 Sep 78

     (5)  Operation and maintenance costs.

     (6)  Number and types of operating personnel required.

     (?)  Waste-water characteristics and flows.

     (8)  Level of odors, noise, and insects.

     (9)  Acceptability of aesthetics.

    (10)  Flexibility of system.

    (ll)  Aesthetic and social concerns.

    (12)  Climate—seasonal variation.

3-2.   Design Steps.  The principal phases of design can be subdivided
into four steps:  site selection, determination of waste flows and
strengths, and system selection.

    a«   Site Selection.  Site selection includes a review of the techni-
cal and aesthetic factors listed in paragraph 3-la.

    "b-   Calculation of Flows.  The calculation of wastewater flows to a
treatment facility was discussed in Chapter 2.

    c.   Calculation of Waste Strength.  The strength of waste from most
domestic sources is known (Table 2-2)  and was discussed in Chapter 2.

    d-   System Selection.  Once a site has been selected and waste flows
and strengths have been estimated, the process of selecting/designing
a treatment facility can begin.   This  process includes a review of the
system selection factors (para 3-lb) and a mathematical analysis of one
or more waste treatment systems.  At this point, a computer-based design
procedure may be used to design a system or to review the feasibility of
one or more recommended systems.  Otherwise, the designer may indepen-
dently design a system, exercising his professional judgment in the se-
lection of processes to be considered, and manually compute the size and
operational characteristics of the system.
                                   3-2

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                29 Sep 78

                                CHAPTER U

             DESIGN AND EVALUATION OF PROCESSES AND SYSTEMS

 ^-1.  Factors Determining Process Selection.  Selection of a process
 train (combination of processes) for vastevater treatment will depend on
 a variety of factors including:

    a.  Stream standards and/or receiving water quality.

    b.  Federal, state, and local effluent criteria.

    c.  Wastewater characteristics.

    d.  Economics.

    e.  Availability of fuel and/or electric power.

    f.  Specific exclusions of certain processes.

    g.  Possible requirements for future expansion and/or upgrading.

 ^-2.  Process Substitution Diagram.  The process substitution diagram
 (fig- ^-l) is useful in system design and evaluation.   In practice, the
 diagram is entered from the left and the designer may select processes
 for preliminary, primary, secondary, tertiary, and/or sludge treatment
 according to specific needs.  For a given set of wastewater character-
 istics, there may be 30 or more viable treatment processes; a complete
 treatment system may employ from 1 to 10 processes.  Thus, there are
 literally thousands of possible combinations and it is virtually impos-
 sible for an individual designer or design team to evaluate all viable
 processes and combinations of processes without the aid of the computer.
 To limit the amount of evaluation required,  the designer must rely
 heavily on experiences and examples set by others to select processes or
 eliminate certain processes from consideration.   This  practice places a
 great burden on the designer and occasionally results  in designs that
 are far from an economic optimum.

 ^-3-  Process Design.   Specific design equations and practices for Uo
 chemical,  physical,  and biological unit processes are  given in Chap-
ter 5.   The coverage of each process includes the following:

    a.   Background data.
                                   U-i

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ro

PRE- TREATMENT
0»
(D
*0
PRIMARY TREATMENT SECONDARY TREATMENT
CHEMICAL
ntYStCAL DISSOLVED ORGANICS

h»j i-
«
f*

' SCREENING AMD ._
• GRIT REMOVAL ,
. EQUALIZATION 1.
' AND STORAGE jT*
OIL ..
• SEPARATDN j
» AERATED L.
* LAGOOM1 4["
> PONDS ••
S
TRICKLING
• FILTERS t *
» DILUTION [-«


• Mrt- *
OH.ORIKATION ,
*
1^ NEUTRALIZATION ^
t
*
CHEMICAL
• ADDITION FOR «
COAGULATION 1*
[^ PHOSPHORUS L

I*1
\

SUSPENDED SOLIDS
TERTIARY
TREATMENT


fc SPRAT .
MITIGATION ,,
~ FLOTATION [-•
* ll|
• SCOMENTATION J
1}


ACTIVATED 4
• SLUDGE
PROCESSES U *
TRICKLING •<
' FR.TH 4 .
„ STABILIZATION ,
" PONDS (3 TYPtSl s
B AC RATED
* LAGOONS 4 4
FACULTATIVE
• LAGOONS ,5 "
LAW
TREATMENT ,,
^ PHOSPHORUS „
REMOVAL „-
T
* ^ SCOHENTAriOM ^J
. U— ^~~ 'n
u.
M-
K
•
»J

^ LAND _
"* TREATMENT „
«J NITRIFICATION ^J"*
£ COAGULATION
* SEDHENTATKW 17
J FILTRATION *

* EXCHANGE *
• CHLORtNATUN «
1
j. -L
LIQUID

^ RECEIVING
I 	 _ 	 2J
. LAND DISPOSAL
* AND SEEPAGE j,
EVAPORATIVE
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11


• DIGESTION L. i" 1
»hi * 1

SUPERNATANT OR DECANT t »^ _J 4
LEGEND
	 LIQUID WASTE STREAM
	 SOLIDS WASTE STREAM
1] PRIMARY SLUDGC
13A ACTIVATED SLUDGE
• 'ROUGHMG" SYSTEMS FOR
HIGH BOD WASTE
•* MAT IE USED W SCRIES
K" VACUUM *1 * LANDFILL
1
£* CENTRIFUGATKM *


LAGOONS OR V*
^, MYING BFDS 1

** OTHERS ~

DIGESTION DEWATEMING | DISPOSAL
SOL IDS HANDLING
                                                                                                   U) \J1
             Figure U-l.  Wastewater treatment  sequence processes substitution diagram.

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                                                            EM 1110-2-501
                                                              Part  1  of 3

                                                               29 Sep  78
    b.   Input  data requirements.

    c.   Design parameters  (normal operating ranges).

    d.   Design procedures.

    e.   Output data.

    f.   Example calculations.

    g.   Bibliography.

^-^'  Economic Analysis.  The user is referenced to Chapter 8 for a dis-
cussion  on cost estimating and economic analysis of wastewater treatment
facilities.

^-5-  Bibliography.

    a.  U. S. Environmental Protection Agency, "Guidance for Facilities
Planning," Jan 1971*,  Washington, D.  C.

    b.  Water Resources Council, "Water and Related Land Resources,
Establishment of Principles and Standards for Planning," Federal Regis-
ter, Vol 38, No.  1?H, Sep 1973, pp 2^778-2^869.                      	

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
                                CHAPTER 5

                         PHYSICAL UNIT PROCESSES

                        Section I.  INTRODUCTION

5-1. _  Definition.  Those wastevater treatment processes that employ
SSt™  tf0rCe8 (meC?anica1' gravimetric,  etc.) as a principal means of
treatment are generally referred to as physical unit processes or unit
operations.   The physical unit processes described in this chapter are:

    a.  Grit removal.

    b.  Screening.

    c.  Comminution.

    d.  Equalization.

    e.  Flotation.

    f.   Thickening  (gravity).

    g.   Sedimentation  (primary clarifier).

    h.   Sedimentation  (secondary clarifier).

    i.   Filtration.

    j-   Vacuum filtration.

   k.    Centrifugation.

   1.   Microscreening.

   m.   Drying beds.

   n.   Postaeration.

   o.   Sludge hauling  and landfilling.

   p.   Multiple-hearth incineration.

   I-   Fluidized bed incineration.


                                 5"1                 (next  page is  5-3)

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                                                           EM 1110-2-501
                                                             Part 1 of 3

                                                                29 Sep 78
                         Section  II.   GRIT REMOVAL
 5-2.   Background.
     a.   Grit  removal  is  classified  as a protective or a preventive
 measure.   The process does not  contribute materially to the reduction
 in the  pollutional  load  applied to  the wastewater treatment facility.
 Grit chambers are designed to remove grit which may include sand,
 gravel,  cinder,  and other inorganic abrasive matter.  Grit causes wear
 on pumps,  fills  pump  sumps and  sludge hoppers, clogs pipes and channels,
 and occupies  valuable space in  sludge digestion tanks.  Grit removal,
 therefore, results  in the reduction of maintenance costs of mechanical
 equipment  and the elimination of operational difficulties caused by
 grit.   Grit removal is recommended  for small as well as large treatment
 facilities and for  those served by  combined as well as separate sewer
 systems.   Bar screens are usually installed ahead of grit chambers to
 remove  large  floating objects.

     b.   Grit  removal  is normally accomplished through control of veloc-
 ity and  settling time.  The objective is to settle the grit particles
 while keeping the putrescible matter in suspension.  Theoretically, it
 is  desirable  to  remove all grit; however, experience indicates that re-
 moving 65-mesh grit,  i.e. grit  that is retained on a 65-mesh screen,
 provides sufficient protection  to mechanical equipment and eliminates
 the majority  of  operational troubles caused by the grit.   To remove the
 65-mesh grit  with a minimum of  putrescible matter, a flow-through veloc-
 ity of 0.75-1.25 fps  must be provided at all flows.

     c.  The type of settling that normally takes place in a grit chamber
 is  classified as discrete settling, since each particle retains its
 identity while settling at a constant rate.   The design of such a
 chamber is usually based on an  overflow rate that- exceeds the settling
velocity of the  smallest particle desired to be removed.   Smaller par-
ticles are removed in proportion, according to the ratio  of their set-
tling velocities to the settling velocity of the smallest particle that
is, theoretically, 100 percent removed.   The overflow rates selected in
the  design of a grit  chamber must,  therefore, exceed the  settling
velocity of the 65-mesh particle.   Grit  settling velocities are sum-
marized in Table 5-1.

    d.  Grit  chambers may be classified  generally as either horizontal
flow or aerated.   In the horizontal flow type,  the velocity is con-
trolled by the dimensions of the chamber or  by the use of a proportional
weir or a Parshall flume at  the effluent end of the chamber.   Aerated
                                 5-3

-------
EM 1110-2-501
Part 1 of 3
 29 Sep  78

grit chambers consist of a spiral flov aeration tank with the spiral
flow velocity controlled by the dimensions and 'the quantity of air sup-
plied to the chamber.  These chambers are very efficient and the grit
will be washed and easy to handle.  Aerated grit chambers provide a
detention time of 3 min at the maximum rate of flow.  Mechanical grit
removal equipment is usually recommended.

    e.  In summary, the design of grit chambers depends on the type
selected, type of grit removal equipment, specification of the selected
grit removal equipment, and the quantity and quality of the grit to be
handled.

    f.  Extensive discussion of grit removal is presented in the bibli-
ography (para 5-9 below).

    g.  As the trend toward mechanization of wastewater treatment facil-
ities continues to increase at a rapid rate, it is becoming a common
practice to include grit removal facilities in the design of treatment
systems serving small, as well as large, communities.  Picnickers and
campers in some recreation areas either maliciously or accidentally drop
cans, bags, bottles, sticks, and rocks into vault toilets, trailer dump
 stations, and other facilities.  Hence, wastewater characteristics
should be thoroughly examined to determine the need for grit removal
 facilities in the design of systems for recreation areas.  Figure 5-1
 shows a typical aerated grit chamber.  Figure  5-2 shows a typical hori-
 zontal  flow grit chamber.

 5-3.  Input Data.

    a.  Wastewater Flow.

     (l)  Minimum and peak flows, mgd.

     (2)  Average daily flow, mgd.

    b.  Wastewater  Characteristics  (not  applicable).

 5-1*.  Design  Parameters  (Tables  5-1 and  5-2).

     a.  Horizontal  Flow  Grit  Chamber.

     (l)  Particle  size,  mm.

     (2)  Specific  gravity.

-------
                                                           EM  1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
               SWING DIFFUSER IN
               RAISED POSITION
MONORAIL SUPPORT
                ALUMINUM PIPE
                RAILINGS
                     SWING
                     DIFFUSER
                     ASSEMBLY
        DIFFUSER TUBE ASSEMBLY-*
                                         HEADER /
                                         STOp
                                       x- CONCRETE SADDLE UNDER EACH TEE
                                      f   AND HALFWAY BETWEEN TEES
                                            SWING JOINT
                                           MAX WATER SURFACE
   UPPER HANGER PIPE


   KNEE JOINT


   LOWER HANGER PIPE
                                                        /•Irom Metcalf and
                                                        Eddy, 1972
     Figure 5-1.   Schematic of a typical aerated grit  chamber.


v_ 	 .__
/^>>>> "^^^


^OOOO^^N^V^ V^^^v »^vvJ
. S. S Si V Vfo
s
S,
s
s
•s
s
y^^ W^
                            PLAN VIEW
^7

^ GRIT WEIR_^
^v;^^^^^^^'^^. . . •'•••'•

\
\
A.N
\





                           SIDE VIEW             ^FLUSHING SUMP

Figure  5-2.   Schematic of a  typical horizontal flow grit chamber.
                                5-5

-------
EM 1110-2-501
Part 1 of 3

 29 Sep 78

    (3)  Maximum and average velocities, fps.


    (U)  Current allowance (l.?)-

                           3
    (5)  Volume of grit, ft .


    (6)  Number of units.


    b.  Aerated Grit Chamber.


    (l)  Detention time, min.


    (2)  Air  supply, cfm/ft.


    (3)  Maximum and average velocities, fps.

                            3
    (k)  Volume of grit,  ft  .


     (5)   Number of units.


 5-5.   Design Procedure.


    a.  Horizontal  Flow Grit Chamber.


     (1)   Select the number of units and calculate flow per unit,

                                        QT
                               Q/unit = —


 where

     0  = total flow to plant, mgd


       N = number of units


      (2)  Select maximum controlled velocity,  v « 1.25 fps.


      (3)  Calculate cross-sectional area.
                                 v
                                  max

  where

                                     2
         A = cross-sectional  area, ft


                                    5-6

-------
                                                            EM 1110-2-501


                                                              Part 1 of 3


                                                                29 Sep 78



     Q    = maximum flow/unit,  mgd
      IHcljC




     Vmax = maximum controlled  velocity,  fps




     (k)   Assume depth and calculate  width or vice  versa.







                                  A = WD


 where




     W =  channel width,  ft




     D =  channel depth,  ft




     (5)   Calculate  settling velocity of the smallest particle  desired

 to be 100$ removed  (according to  Table 5-1 or calculations).




          Size « 0.2 mm




          Specific gravity « 2.65
                   V  =
                    s
                              3.28 x io~3
                                                 1/2
where
             vg = settling velocity of smallest particle that is


                  100$ removed, fps



                                                      r)

              g = gravitational acceleration,  32.2 fps




             c  = drag coefficient





             P  = specific gravity of the particle
              S



             d  = diameter of the particle,  mm
                                  5-7

-------
EM 1110-2-501

Part 1 of 3

 29  Sep  78
             R  = Reynolds number = - £ - -

              n                     v x 3.28 x lo"-3



              v = kinematic viscosity of the liquid, ft /sec

             _o
    3.28 x 10   = conversion factor, mm to ft



    (6)  Calculate the length of each channel.



                               /v    \
                      L=D    /JE93L}(1.7)
                           max I  v   /
                               \  s  /


where


        L = length of the channel, ft



     D    = depth at maximum flow, ft
      max


     v    = velocity at maximum discharge, fps
      max


       v  = settling velocity of the smallest particle that is 100%

            removed, fps



      l.T = allowance for currents



     (T)  Calculate detention time.
                                 Q x i.lt


 where


         t  =  detention time,  sec



         D  =  channel  depth, ft



         W  =  channel  width, ft



         L  =  length of channel, ft



         Q  =  flow,  mgd



      1.5U  =  conversion  factor, mgd to  cfs




                                  5-8

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
     (8)  Calculate bottom slope of channel.
                         v
                          avg    n
where
    v    = velocity at average discharge, fps

       n = Manning's coefficient (a value of 0.03 may be used)
                                                 A
       R = hydraulic radius of cross section =         for rectangular
           channel                             2D   W

       S = slope

    (9)  Calculate approximate volume of grit.  The volume of grit may
vary from less than 1 ft3 to more than 12 ft3 per million gal of waste-
water.  It must also be noted that the grit collected from a horizontal
flow grit chamber will contain a high amount of putrescible matter and
should be washed before disposal.
               o
    Assume h ft /million gal (approximate)
                                V  = UQ
                                 g
where
                           o
    V  = volume of grit, ft /day
     O
     Q = flow, mgd

    (10)  Design control section at outlet.

    b.   Aerated Grit Chamber.

    (1)  Calculate the length of channel.

                         _ (t)(Q
                       L = -
where


                                 5-9

-------
EM 1110-2-501

Part 1 of 3

'29 Sep  78


     L = length of channel, ft


     t = detention time, min


    Q  = peak flow, mgd

                                 2
     A = cross-sectional area, ft


    (2)  Calculate air requirements, cfm.



                           Total air = L x O^/ft


where


        L = length of chamber


    0 /ft = air supply per ft of length  (Table 5-2)


5-6.  Output Data.


    a.  Horizontal Flow Grit  Chamber.


      (l)  Maximum flow, cfs.


      (2)  Average flow, cfs.


      (3)  Minimum flow, cfs.


      (U)  Temperature,  °C.


      (5)  Maximum flow-through velocity,  fps.


      (6)  Average flow-through velocity,  fps.


      (7)   Size smallest particle 100% removed, mm.


      (8)   Specific  gravity of particle.


      (9)   Number  of units.


     (10)   Maximum flow/unit,  cfs.


     (11)   Width of channel, ft.
                                   5-10

-------
                                                          EM 1110-2-501
                                                            Part 1 of 3
                                                              29 Sep 78

    (12)  Depth of channel, ft.

    (13)  Length of channel, ft.

    (14)  Settling velocity of particle, fps.

    (15)  Slope of channel bottom.

    (16)  Allowance for  currents.

    (17)  Detention time, sec.

    (18)  Manning's coefficient.

    (19)  Volume of grit, ft3/day.

    (20)  Design outlet  control  section.

    "b.  Aerated Grit  Chamber.

    (l)  Detention time, min.

    (2)  Air supply,  cfm/ft.

    (3)  Length, ft.

    (it)  Total air requirement,  cfm.

5-7.  Example Calculations.

    a.   Horizontal Flow Grit  Chamber.

    (1)  Select number of units  and calculate flow per unit.
                                unit   N


where

          Q  = total flow to plant = 1 mgd

           N = number of units = 1


                                 5-11

-------
EM 1110-2-501

Part 1 of 3

29 Sep 78
                            .'. Q/unit =
                              Q./unit = 1



     (2)  Select maximum controlled velocity,  v « 1.25 fps,


     (3)  Calculate cross-sectional area.
                                 V
                                  max
 where

                                    2
        A = cross-sectional area, ft


     Q    = maximum flow/unit, 1 mgd
      max

     v    = maximum controlled velocity, 1.25
      max

     1.5U = conversion factor
                          "   1.25



                            A =  1.23  ft2



           Assume depth and calculate  width.
  where


        W = width, ft

                                         2
        A = cross-sectional area, 1.23 ft




                                   5-12

-------
                                                          EM 1110-2-501
                                                            Part 1 of 3

                                                              29 Sep 78
      D = assumed depth,  1  ft


                           . ..   1.23 ft2
                           .. W =
                                   1  ft



                             W =  1.23 ft


    (5)  Calculate settling velocity  of smallest particle desired to be

100% removed from Table  5-1.


                              Size w 0.2 mm



                        Specific  gravity « 2.65


                                                   1/2
where
                    v  =
                     s
                          (V3)(g/cd)(Ps  -
3.28 x 10 3
                         c  =      +    -    (0.3U)
                          d   VW
             v  = settling velocity of smallest particle that  is  100%
              o
                  removed, fps

                                                      2
              g = gravitational acceleration, 32.2 fps


             c  = drag coefficient


             P  = specific gravity of particle, 2.65
              S

             d  = diameter of particle, 0.2 mm
              P
             R  = Reynolds number =
                                    v x 3.28 x
                                  5-13

-------
 EM 1110-2-501
 Part 1 of 3
 29 Sep 78
              v = kinematic viscosity of liquid (use 1.0 x  io~5  ft2/sec)

    3.28 x 10   = conversion  factor, mm to ft
    From Table 5-1 select   v
                            s
                       v  =  3.7 ft/min = 0.06 fps
                        S
    (6)  Calculate the  length of each channel.
                          L = D
                              max \ v  /
                                  \  s '

where

       L = length of  channel, ft

    D    = depth at maximum flow, 1 ft

    Vmax = velocity of maximum discharge,  1.25 fps

      vg = settling velocity of smallest particle 100$ removed, 0.06 fps

     1.7 = allowance  for currents
                            L = x (m) ^
                              L = 35.^ ft

    (7)  Calculate  detention time.

                                = (D)W(L)
                                  Q x 1.5

where

       t = detention time, sec

-------
                                                          EM 1110-2-501

                                                            Part 1 of 3

                                                              29 Sep 78
      D = channel depth, 1 ft



      W = channel width, 1.23 ft


      L = channel length, 35-^ ft



      Q = flow, 1 mgd


    1.5^= conyersion factor, mgd to  cfs



                            t = 1(1.23)35.**






                              t =  28.3 sec




    (8)   Calculate  bottom slope  of  channel.



                                       32/30l/2
                                          q
                          V    = ~~~~~^ K   o
                           avg    n
where
    v    = velocity at average discharge, 1.23 fps
     avg

       n = Manning's coefficient (use 0.03)


       R = hydraulic radius = 2pA+ y for rectangular section



       S = slope
                               R=
                                    2D  + W



where


       A =  area,  1.23  ft2


       D =  depth, 1.0  ft



       W =  width, 1.23 ft





                                  5-15

-------
 EM 1110-2-501

 Part 1 of 3

   29 Sep  78
        R =
            2 + 1.23


        R = 0.38
                                     (0.38)3/2S1/2
                            S =  0.01 ft/ft




     (9) .  Calculate approximate  volume of grit assuming k ft3/million gal.




                                V   = UQ
                                 O


vhere



     V  =  volume of grit, ft3/day
     &


     Q =  flow, mgd




                              v  = MD
                              o


                              V  = U  ft3/day
                              pi _______



5-8.  Cost Data.  Appropriate cost data and economic evaluation may be
found in  Chapter 8.



5-9-  Bibliography^



     a.  American Society of Civil Engineers and the Water Pollution

Control Federation, "Sewage Treatment Plant Design," Manual of Practice

No.  8, 1959, 1961, 1967, 1968, Water Pollution Control Federation,
Washington, D. C.



    "b.  Camp, T. R. , "Grit Chamber Design," Sewage Works Journal.

Vol  Ik, No. 2, Mar 19^2, pp 368-381.



     c.  Fair, G. M. , Geyer, J. C. , and Okun, D.  A., Water Purification

and Wastewater Treatment and Disposal;  Water and Wastewater Engineering

Vol 2, Wiley, New York, 1968.               ~~                -



                                 5-16

-------
                                                           EM 1110-2-501
                                                             Part  1 of 3
                                                               29  Sep  78
    d.  FMC Corporation, "Link-Belt Wastewater Treatment Equipment
Design Catalogue," Binder 2650, Colmar, Pa.

    e.  Lee, M. L. and Babbitt, H.  E. , "Constant Velocity Grit Chambers
with Parshall Flume Control," Sewage Works Journal, Vol 18, No.  4,
Jul
    f.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection,
Treatment, and Disposal, McGraw-Hill, New York, 1972.

    g   Neighbor, J. B. and Cooper, T. W. , "Design and Operation
Criteria for Aerated Grit Chambers," Water and Sewage Works. Vol 112,
Dec 1965, PP
                                  5-17

-------
 EM 1110-2-501
 Part 1 of 3
 29  Sep  78
                   Table 5-1.  Grit Settling  Velocities
Particle Size
Mesh
18
20
35
k&
65(a)
100
150
I „ ^
mm
0.833
0.595
0.1+17
0.295
0.208
0.1U7
0.105
Settling Velocity
ft/min
lit. 7
10.5
7.1*
5.2
3.7
2.6
1.8
gpd/ft2
160,000
114,500
80,100
56,700
Uo,ooo
28,200
20,200
mgd/ft2
0.1600
0.111*5
0.0801
0.0567
0.01*00
0.0282
0.0202
Area Required
2
ft /million gal
6.3
8.7
12.5
17-7
25.0
35.5
1*9.5
       Minimum particle size desirable for removal.   »<"» Met">>f'»* ™dy, 1972
         Table  5-2.   Design Parameters for Aerated Grit Chambers



1.  Air supply  -  3 cfm/ft  of tank length


2.  Air diffusers -  located 2 to 3 ft above tank bottom on one  side  of
      tank


3.  Surface velocity - 1.5 to 2  fps


1*.  Tank floor velocity -  1 to 1.5 fps


5.  Grit collectors  - air  lift pumps  to decanting channels, grit con-
      veyors or grit pumps


6.  Detention time - 2 to  3 min


7.  Efficiency - 100$ removal  of 65-mesh grit

                                                      From Metcalf and Eddy, 1972
                                 5-18

-------
                                                          EM  1110-2-501
                                                            Part  1  of  3

                                                               29 Sep 78
                         Section III.   SCREENING
5-10.   Background.
    a.   Screening devices are used normally to remove large floating
objects that otherwise may damage pumps and other equipment,  obstruct
pipelines, and interfere with the normal operation of the treatment
facilities.  Screens used in wastewater treatment facilities  or in pump-
ing stations are generally classified as fine screens or bar  screens.

    b.   Fine screens are those with openings of less than lA in.  These
screens have been used as a substitute for sedimentation tanks to  remove
suspended solids prior to biological treatment.  However, few plants
today use this concept of solids removal.  Fine screens may be of  the
disk, drum, or bar type.  Bar-type screens are available with openings
of 0.005 to 0.10 in.

    c.   Bar screens are used mainly to protect pumps, valves, pipelines,
and other devices from being damaged or clogged by large floating  ob-
jects.   Bar screens are sometimes used in conjunction with comminuting
devices.  Bar screens consist of vertical or inclined bars spaced  at
equal intervals  (usually 3A to 3 in.) across the channel where waste-
water flows.  These devices may be cleaned manually or mechanically.
Bar screens with openings exceeding 2-1/2 in. are termed trashracks.

    d.  The quantity of screenings removed by bar screens usually de-
pends on the size of the bar spacings.  Since the handling and disposal
of screenings is one of the most disagreeable jobs in wastewater treat-
ment, it is usually recommended that the quantity of screenings be kept
at a minimum.  Amounts of screenings  from normal domestic wastes have
been reported from  0.5 to 5  ft3/million gal of wastewater treated.
Screenings may be disposed of by burial, incineration, grinding, and
digestion.

    e.  Design of bar  screens is based mainly on average and peak
wastewater flow.  Normal design and operating parameters are usually
presented  in the manufacturer's specifications.  The bibliography
 (para  5-17) presents  a thorough discussion of the design, operation,
and maintenance  of  screening devices.  General characteristics of bar
and fine  screens are  presented in Tables 5-3 and 5-l|,  respectively.
Figure  5-3 shows a  mechanically cleaned bar rack.
                                  5-19

-------
 EM 1110-2-501
 Part 1  of 3
  29 Sep  78
                      \"j'.':'.'-.'. ;•'•.'••.y':''•'•.'• W'  From Air Force Manual 88-11
                 Figure  5-3.  Schematic of a mechanically
                              cleaned bar rack.
5-11.  Input Data.

    a.  Wastewater Flow.

    (l)  Average daily flow, mgd.
                                   5-20

-------
                                                          EM 1110-2-501
                                                            Part 1 of  3
                                                               29 Sep 78

    (2)   Maximum daily  flow, mgd.

    (3)   Peak wet weather  flow, mgd.

    b.   Wastewater  Characteristics  (not  applicable).

5-12.   Design Parameters.

    a.   Type of bar screen.

    (l)   Manually cleaned.

    (2)   Mechanically cleaned.

    b.   Velocity through bar screen, fps (Table 5-3).

    c.   Approach velocity, fps (Table 5-3).

    d.   Maximum head loss through screen, in. (Table 5-3).

  •  e.   Bar spacings, in.  (Table 5-3).

    f.   Slope of bars, deg (Table 5-3).

    g.   Channel width, ft.

    h.   Width of bar, in.

    i.   Shape factor.

 5-13.   Design Procedure,.

    a.   Consult  equipment manufacturer's specifications and select
 a bar screen which meets  design requirements.

    b.   Calculate head loss through the  screen.  It should be noted  that
 when screens  start to become clogged between cleanings in manually
 cleaned screens  head loss will increase.
(w
\b
                                            sin2
                                            2g
                                  5-21

-------
 EM 1110-2-501

 Part 1 of 3


 29 Sep 78



 where




     h  =  head loss through the screen, ft



      3 =  bar  shape factor




        =  2.U2 for sharp-edged rectangular bars




        =1.83 for rectangular bars with semicircular upstream faces



        =1.79 for circular bars



        =1.67 for rectangular bars with semicircular upstream and

          downstream faces




        =0.76 for rectangular bars with semicircular upstream faces

          and  tapering in a symmetrical curve to a small circular

          downstream face (teardrop)



     W = maximum width of bars facing the flow, in.




     b  = minimum width of the clear spacings between pairs of bars, in.



     v  = longitudinal approach velocity, fps



     0  = angle of the rack with horizontal, deg



     g  = gravitational acceleration



    c.  Calculate average depth.
                            D   "  "(wc)Tv)
where



       D = average depth, ft



    Q    = average flow, mgd



      W  = channel width, ft
       c


       V = average velocity, fps





                                 5-22

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep  78
    d.   Calculate maximum depth.
where
    D    = maximum depth, ft
     max
       D = average depth, ft
      Q  = peak flow, mgd
    0    = average flow, mgd
     avg
5-ll}.  Output Data.
    a.  Bar size, in.
    b.  Bar spacing, in.
    c.  Slope of bars from horizontal,  deg.
    d.  Head loss through screen,  ft.
    e.  Approach velocity,  fps.
    f.  Average flow-through  velocity,  fps.
    g.  Maximum flow-through  velocity,  fps.
    h.  Screen channel  width, ft.
     i.   Channel depth,  ft.
 5-15.   Example  Calculations.
     a.   Select  a  mechanically cleaned bar screen from Table 5-3 with bar
 screen size of width =  1/U in., depth = 1 in., spacing = 5/8 in., slope
 = 10 deg, approach velocity = 2 fps, and allowable head loss = 6 in.
     b.   Calculate head loss through screen.

                                  5-23

-------
 EM 1110-2-501
 Part 1 of 3
 29 Sep 78
 where

     hg  =  head loss,  ft

     3  =  "bar  shape factor,  1.83

     W  =  width =  lA in.

     b  =  spacing  = 5/8  in.

     v  =  approach velocity  =  2  fps

     0  =  slope  of rack  = 10 deg

     g  =  gravitational  acceleration =  32.2  ft/sec2
                                        |"22(sin210)"|
                                        L   2(32.2)  J
                       = 0.001 ft
    c.  Calculate the average depth.


                                 (Q    )(l.5lO
                            D = _aZS.	_
                                   Wc(v)
where

       D = average depth, ft

    Save = averaSe fl°w)

      W  = channel width, 1.23 ft

       v = average velocity, 2 fps


                                 5-21+

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29  Sep  78
                               "   1.23(2)

                             D = 0.63 ft

    d.  Calculate maximum depth.
                             max     \avg
where
    D    = maximum depth, ft
     max
       D = average depth, 0.63 ft

      Q  = peak flow, 2 mgd

    Q    = average flow, 1 mgd
     avg

                             D    = 0.63(f)
                              max        \ 1 /

                             D    = 1.26 ft
                              max _

5-16.  Cost Data.  Appropriate cost data and economic evaluation may
be found in Chapter 8.

5-17.  Bibliography.

    a.  American Society of Civil Engineers and the Water Pollution
Control Federation, "Sewage Treatment Plant Design," Manual of Practice
No. 8, 1959, 1961, 1967, 1968, Water Pollution Control Federation,
Washington, D. C.

    b.  Equipment Manufacturers' Catalogs.

    c.  Fair, G. M. ,  Geyer, J. C. , and Okun, D. A., Water Purifica-
tion and Wastewater Treatment and Disposal; Water and Wastewater Engi-
neering, Vol 2, Wiley,  New York, 1968.
                                  5-25

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78
    d.  Goodman, B. L. , Design Handbook of Wastewater Systems-
Domestic, Industrial. Commercial. T*nV.n™n-,, , u^^^ !Lnn  ^
   _e.  Great Lakes-Upper Mississippi River Board of State Sanitary
Engineers,  Recommended Standards for Sevage Works (Ten States Stan-
dards),  1971, Health Education Service, Albany, N. Y.

    f.  Metcalf and Eddy, Inc., Wastevater Engineering: Collection
ireatment, and Disposal. McGraw-Hill, New York, 1972.   - ~~~^
                               5-26

-------
                Table 5-3.  General Characteristics of
                              Bar Screens
                 Table 5-*K   General Characteristics of
                              Fine Screens
                                                          EM 1110-2-501
                                                            Part 1 of 3
                                                              29 Sep 78
Item
Bar screen size
Width, in.
Depth , in .
Spacing, in.
Slope from vertical, deg
Approach velocity, fps
Allowable head loss, in.
Hand Cleaned
lA to 5/8
1 to 3
1 to 2
30 to U5
1 to 2
6
Mechanically
Cleaned
lA to 5/8
1 to 3
5/8 to 3
0 to 30
2 to 3
6
      Item
                                   Disk                   	Drum
Fine screen
  Openings, in.               0.126 to 0.009              0.126 to 0.009
                              (6 to 60 mesh)              (6 to 60 mesh)
  Diameter, ft                    U to 18                    3 to 5
  Length, ft                                                 U to 12
rpm
                                  5-27                (next page is 5-29)

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78

                        Section IV.  COMMINUTION
5-l8.  Background.
    a.  Comminutors are screens equipped with a device that cuts and
shreds the screenings without removing them from the waste stream.
Thus, comminuting devices eliminate odors, flies, and other nuisances
associated with other screening devices.  A variety of comminuting
devices are available commercially.

    b.  Comminutors are usually located behind grit removal facilities
in order to reduce wear on the cutting surfaces.  They are frequently
installed in front of pumping stations to protect the pumps against
clogging by large floating objects.

    c.  The comminutor size is based usually on the volume of waste to
be treated.  Treatment plants with a wastewater flow below 1 mgd
normally use one comminutor.  Table 5-5 summarizes design characteris-
tics of comminutors.

    d.  In wastewater treatment facilities for recreation areas, one
comminutor may be installed in the wet well to protect the pump from
large floating objects.  In the treatment of vault waste, a comminutor
may be included as an integral part of a vault waste holding station.
Figure 5-k shows a comminutor.

5-19.  Input Data.

    a.  Wastewater flow, mgd.

    (l)  Average daily flow, mgd.

    (2)  Maximum flow, mgd.

    b.  Wastewater characteristics (not applicable).

5-20.  Design Parameters.  None.

5-21.  Design Procedure.  Select comminutor from equipment manufac-
turer's catalog to correspond to maximum wastewater flows.

5-22.  Output Data.

    a.  Comminutor specifications.


                                  5-29

-------
EM 1110-2-501
Part  1  of 3
29 Sep  78
            BYPASS BAR
             SCREEN
                       CLOCKWISE
              *        ROTATION
              I CONDU/T'BOX
    STOP GATES
                                              COUNTERCLOCKWISE
                                                 ROTATION
                                 PLAN
                2-HP MOTOR AND
                 GEAR REDUCER
                                         •36A COMMINUTOR
             :«: :••»••  * ^-SiCi:
             •  .*'•'.'>.'•. r'. ' * •
                3'-0" D/AWETER
                                              *.
                                             -VALVED DRA/N FOR DEWATERING
                                                  COMMINUTOR CHANNEL
                                                 From Metcalf and Eddy, 1972
                             SECTION A-A
             Figure 5-i*.  Schematic of a  typical comminutor.
                                    5-30

-------
                                                           EM 1110-2-501
                                                              Part  1  of  3

                                                               29  Sep 78
    b.  Number of commimrtors .

5-23.  Example Calculations.  None.

5-2it.  Cost Data.  Appropriate cost data and economic evaluation may be
found in Chapter 8.

5-25.  Bibliography.

    a.  American Society of Civil Engineers and the Water Pollution
Control Federation, "Sewage Treatment Plant Design," Manual of Practice
No. 8, 1959, 1961, 1967, 1968, Water Pollution Control Federation,
Washington, D. C.

    b.  Fair, G. M., Geyer, J.  C., and Okun, D. A., Water Purifica-
tion and Wastewater Treatment and Disposal; Water and Wastewater Engi-
neeringy  Vol 2, Wiley, New York, 1968.

    c.  Goodman, B. L., Design Handbook of Wastewater Systems:  Do-
mestic, Industrial, Commercial, Technomic, Westport, Conn., 1971.

    d.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection,
Treatment, and Disposal, McGraw-Hill, New York, 1972.
                                 5-31

-------
Table 5-5-   Comminutor Size  Selection
Standard Sizes
Drum
Diameter
in.
4
7
7
10
15
ui 25
i
u>
25
36

Drum
rpm
56
56
56
45
37
25


25
15
Avg Slot
Width
in.
1/4
1/4
1/4
1/4
1/4
3/8


3/8
3/8

Horse-
power
1/4
1/4
1/4
1/2
3/4
1-1/2


1-1/2
2


Height
2 ft 3-1/4 in.
4 ft 3 in.
4 ft 3 in.
4 ft 5 in.
4 ft 11-1/2 in.
5 ft 9-1/2 in.


6 ft 11-1/2 in.
9 ft 4-1/2 in.
Net
Weight
Ib
175
450
450
650
1100
2100


3500
8500
Rates of
Flow
Avg 12 -hr Day
Time,
0 to
0.03 to
0.06 to
0.17 to
0.25 to
0.97 to


1.00 to
1.30 to
mgd
0.035
0.113
0.200
0.720
1.820
5.100


9.400
20.00
Maximum Hourly
Rates of Flow
mgd
0.09
0.24
0.36
1.08
2.40
6.10


11.10
24.00
TO p
^O »iii
- o ?
1
L>J\J]










                                                 From Goodman, 1971

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78

                        Section V.  EQUALIZATION

5-26.  Background.

    a.  Equalization is a unit operation used for highly variable waste
flows or strengths to provide a uniform discharge and/or concentration
to a treatment facility or receiving streams.  Experience has shown that
treatment processes (physical, chemical, or biological) perform better
if extreme load fluctuations enroute to the process can be settled.
Equalization before biological treatment prevents slugs of toxic sub-
stances and provides a uniform organic loading to the system.  Equali-
zation may also follow chemical coagulation to facilitate the automatic
pH control schemes and chemical feeding.

    b.  Flow equalization tanks are usually aerated to prevent deposi-
tion of solids and/or the development of anaerobic conditions.   Mixing
requirements for wastewaters having a suspended solids concentration of
approximately 200 mg/£ range from 0.02 to 0.0*1 hp/1000 gal of maximum
storage volume.  Aeration (approximately 15 mg 02/&/hr) is recommended
to prevent septic odor problems.   Airflow rates from 5 to 20 cfm/ft3 of
tank volume are common.

    c.  Design of equalization basins varies with the quantity of the
waste and the pattern of its discharge.   Concentration time profiles
and the frequency flow fluctuations are normally used as a basis  in  the
design of these tanks.   Supplying enough air to keep the basin aerobic
and providing adequate mixing to  prevent solids deposition may be con-
sidered the major factors in equalization basin design.

5-27.   Input Data.

    a.  Flow data.

    (l)   Peak daily flow,  mgd.

    (2)   Average daily flow,  mgd.

    (3)   Minimum daily flow,  mgd.

    b.   Wastewater characteristics.

    (l)   Desired mean  concentration,  mg/£.
               •
    (2)   Time variation in concentration,  hr.
                                  5-33

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78

5-28.  Design Parameters.

    a.  Detention time (dependent on the fluctuation cycle), days.

    "b.  Mixing requirements (0.02 to 0.04 hp/1000 gal).

    c.  Air requirements (5 to 20 cfm/ft ).

    d.  a (0.9).

    e.  3 (0.9).

    f.  Standard transfer efficiency, STE, Ib 0 /hp/hr.

    g.  Oxygen requirements, mg/£/hr.

5-29.  Design Procedure.

    a.  Select detention time based on the cycle of flow fluctuation.

    b.  Calculate volume of basin.


                               V = (Q)(t)

where

    V = volume, million gal

    Q = design flow, mgd

    t = detention time, days

    c.  Assume horsepower requirements for mixing' (manufacturer's
requirements or 20 to UO hp/million gal) and calculate total horsepower
requirement.


                    hp = (hp/1000 gal) x (v) x (lOOO)


    d.  Check horsepower for oxygen requirement to maintain aerobic
conditions.

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                29 Sep 78
    (l)  Calculate 0  required for aerobic conditions.

                  02(lb/hr) = (15 mg/A/hr) x (V) x 8.3^

where

    V = volume of "basin, million gal

    (2)  Calculate 0  transfer at operating conditions.


                           (BCs - C)               T 20
                 OTE = STE - — —  x a x (1.02U)
where
    OTE = operating transfer efficiency, Ib 09/hp/hr

    STE = standard transfer efficiency at zero dissolved
          oxygen (DO), tap water, and 20°C sw 3.8

          Op saturation in waste
                                     0.9
          Op saturation in water

     C  = oxygen saturation at summer temperature
      s

      C = minimum DO concentration in tank as 2 mg/Jl

          0  transfer in waste

          0  transfer in water


      T = temperature, °C

    (3)  Calculate horsepower required to supply 0~ for aerobic
conditions.

                                  0 (Ib/hr)
                             hp =
                                     OTE
    (k)  Compare horsepower calculated from (3) above with horsepower
calculated for mixing (c above), and select the larger of the two
horsepowers.
                                  5-35

-------
EM 1110-2-501
Part 1 of 3

 29 Sep  78

5-30.  Output Data.

    a.  Detention time, days.

    b.  Desired concentration 0 , mg/£.

    c.  Mixing requirements, hp/1000 gal.
                                o
    d.  Air requirements, cfm/ft .

    e.  Volume, million gal.

    f.  Total power requirements, hp.

5-31.  Example Calculations.

    a.  Select a detention time.  It has been determined that a deten-
tion time of 1-1/2 days is necessary for flow equalization.

    b.  Calculate volume of basin.


                                 V = Qt


where

    V = volume, million gal

    Q = average daily flow, 1 mgd

    t = detention time, 1.5 days


                           V = 1(1.5)

                           V = 1.5 million gal


    c.  Assume horsepower requirements for mixing of 30 hp/million gal
and calculate total horsepower requirement.


                       hp = (hp/1,000,000 gal)(V)
                                 5-36

-------
                                                            EM 1110-2-501
                                                              Part 1 of 3

                                                                 29 Sep» 78
 where

     hp/1,000,000 gal = hp required for mixing,  30

                    V = volume, 1.5 million gal


                               hp = 30(1.5)

                               hp = k5

     d.   Check horsepower for oxygen requirement  to maintain aerobic
 conditions.

     (l)   Calculate  0  required for aerobic conditions.


                     0-(lb/hr)  = (15 mg/4/hr)V(8.3M
where
     0  (ib/hr) = oxygen requirement

            V = volume of tank, 1.5 million gal


                       02(lb/hr) = (15)U.5)(8.3M


                               ) = 187.65
    (2)  Calculate the 0  transfer at operating conditions,
                              (3C  - C)
                    OTE = STE    S	 a 1.02HT~20
where

     OTE = operating transfer efficiency, Ib 0 /hp/hr



                                 5-37

-------
EM 1110-2-501
Part 1 of 3

20  Sep 78
     STE = standard transfer efficiency, 3.
      C  = oxygen saturation at temperature T, 7-63 mg/£
       s
       C = minimum oxygen concentration, 2.0 mg/£

       a = 0.9

       T - temperature, 30°C

    9.17 = oxygen saturation at 20°C
              OTE = 3.8 t°'9(T.63) - 2.0] (0<9)1.02U(30-20)


              OTE = 2.3

     (3)  Calculate horsepower required to maintain aerobic conditions.

                                  0  (lb/hr)
                             hp =
                                    OTE

 where

            hp = required horsepower

     0  (lb/hr) = oxygen requirement, 187.65

           OTE = operating transfer efficiency, 2.3

                               hu  = 187.65
                               hp      2.3

                               hp  = 81.6

     (U)  Select larger horsepower requirement  for mixing  or  for  main-
 taining aerobic conditions.
                           hp = 81.6  use 82

                                  5-38

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Scp 78
5-32.  Cost Data.  Appropriate cost data and economic evaluation may be
found in Chapter 8.

5-33.  Bibliography.

    a.  Nemerow, N. L., Liquid Waste of Industry, Addison-Wesley,
Reading, Mass., 1971.

    b.  Reynolds, E., Gibbon, J. D., and Attwood, D., "Smoothing Quality
Variations in Storage Chests Holding Paper Stock," Transactions, Insti-
tution of Chemical Engineers, Vol k2, T13, 196*1.

    c.  Roy F. Weston, Inc., "Process Design Manual for Upgrading Exist-
ing Wastewater Treatment Plants," prepared for the U. S. Environmental
Protection Agency, Technology Transfer, Oct 1971, Washington, D. C.

    d.  Wallace, A. T., "Analysis or Equalization Basins," Journal,
Sanitary Engineering Division, American Society of Civil Engineers,
Vol 9k, SA6, 1968, pp 1161-117!^.

    e.  Wallace, A. T., "Equalization," Seminar on Process Design in
Water Quality Control, 9-13 Nov 1970, Vanderbilt University, Nashville,
Tenn.
                                    °                (next page  is  5-

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78

                         Section VI.   FLOTATION

5-3^.  Background.

    a.  Flotation is a solid-liquid separation process.   Separation is
artificially induced by introducing fine gas "bubbles (usually air) into
the system.  The gas bubbles become attached to the solid particulates,
forming a gas-solid aggregate with an overall bulk density less than
the density of the liquid; thus, these aggregates rise to the surface
of the fluid.  Once the solid particles have been floated to the surface,
they can be collected by a skimming operation.

    b.  In wastewater treatment, flotation is used as a clarification
process to remove suspended solids and as a thickening process to con-
centrate various types of sludges.  However, high operating costs of
the process generally limit its use to clarification of certain indus-
trial wastes and for concentration of waste-activated sludge.

    c.  Air flotation systems may be classified as dispersed air flota-
tion or dissolved air flotation.  In dispersed air flotation, air bubbles
are generated by introducing air through a revolving impeller or porous
media.  This type of flotation system is ineffective and finds very
limited application in wastewater treatment.  Dissolved air flotation
may be subclassified as pressure flotation or vacuum flotation.  Pres-
sure flotation involves air being dissolved in the wastewater under
elevated pressures and later released at atmospheric pressure.  Vacuum
flotation, however, consists of applying a vacuum to wastewater aerated
at atmospheric pressure.  Dissolved air-pressure flotation, considered
herein, is the most commonly used in wastewater treatment.

    d.  The principal components of a dissolved air-pressure flotation
system (fig. 5-5) are a pressurizing pump, air injection facilities,
a retention tank, a back pressure regulating device, and a flotation
unit.  The primary variables for flotation design are pressure, recycle
ratio, feed solid concentration, detention period, air-to-solids ratio,
and solids and hydraulic loadings.  Optimum design parameters must be
obtained from bench scale or pilot plant studies.  Typical design param-
eters are listed in Table 5-6.

5-35.  Input Data.

    a.  Wastewater (or sludge) flow, mgd.

    b.  Suspended solids concentration in the feed, mg/&.

-------
EM 1110-2-501

Part 1 of 3


29 Sep 78'
CHEMICALS
1
' I

T I

CHEMICAL
MIX TANK

PRESSURIZING /"
PUMP ( <
-1
f
THICKENED
Ql llpr^p



_

1 1
RETENTION!
1 SLUDGE COLLECTOR 7~\_ v'
^"•"^ 	 1 	 -1 — *~J~ I
5T 	 	 1 	 1 	

FLOTATION TANK •

BOTTOM SLUDGE COLLECTOR
OFTEN INCLUDED

^7 PRESSURE
)t| REDUCING
nr VALVE
	 .,.,, | From Metcalf a
BAFFLE
EFFLUENT
*





id Eddy, 1972
        Figure 5-5.  Schematic of a dissolved-air flotation tank

                            without recycle.



    (l)  Average concentration.




    (2)  Variation in concentration.




5-36.   Design Parameters.  From laboratory or pilot plant studies.



    a.  Air-to-solids ratio (A/S).



    ID.  Air pressure (P), psig.




    c.  Detention time in flotation tank (DTFT), hr.



    d.  Solids loading (ML), Ib/ft2/day.


                                      f^

    e.  Hydraulic loading (HL), gpm/ft .




    f.  Detention time in pressure tank (DTPT), min.




    g.  Float concentration (CL,), percent.
                              r


5-37-   Design Procedure.




    a.  No Recycle (Direct Pressurization).
                                  5-U2

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
     (l)  Select air-to-solids ratio (from laboratory or pilot plant
studies) (Table 5-6).


     (2)  Calculate the required pressure.-



                               1.3S (0.5P - 1)
                         A/S =
                                     C
                                      o
where


      A/S = air-to-solids ratio, Ib air/lb solids


       S  = air solubility at standard conditions, cc/SL
        £l

        P = absolute pressure, in atmospheres = psig +


       C  = suspended solids concentration in the feed, mg/&


     psig = gage pressure


    (3)  Select a mass loading rate (or hydraulic loading rate) and
calculate surface area.



                                (Q)(C
                                      ML
                                (HL)(60)(2U)


where

                         2
    SA = surface area, ft


     Q = feed flow, mgd


    C  = suspended solids concentration in the feed, mg/£

                            2
    ML = mass loading, Ib/ft /day

                                  2
    HL = hydraulic loading, gpm/ft

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78
         Use the larger of the two areas calculated in (3).

    (5)  Select detention time and calculate volume of flotation tank,
                    VOLFT =
where

    VOLFT = volume of flotation tank, ft3

        Q = total flow, mgd

     DTFT = detention time in flotation tank,  hr

    (6)  Calculate volume of sludge produced.


                             (Q)(C )(%, removal)
                      VSP =
                            (CF)(specific gravity)


where

    VSP = volume of sludge produced,  gpd

      Q = total flow, mgd

     C  = suspended solids concentration

     C  = solids concentration in  float, %

    "b.  With Recycle.

    (l)  Select air-to-solids  ratio.

    (2)  Assume pressure (ho to 60 psig).

    (3)  Calculate  P  in atmospheres =  psig  + lU.7/1^.7

         Calculate recycle flow.

-------
                                                           EM 1110-2-501

                                                             Part  1 of 3

                                                              29  Sep  78



                         ,   1.3S (0.5P - 1)R
                         —     "•
                         S" ~       QC
                                     o



vhere


    A/S = air-to-solids ratio



     S  = air solubility at standard conditions,  cc/£
      a


      P = absolute pressure, atmospheres



      R = recycle flow, mgd


      Q = feed flow, mgd


     C  = influent suspended solids concentration, mg/£
      o


    (5)  Select a mass loading rate (for thickening)  or hydraulic  load-

ing rate (for clarification) and calculate surface area.
                                (Q)(C )(8.3lO
                           SA = —
                                      ML
                           qfl - (Q + R)do6)
                                (HL)(60)(2iO



where

                         2
    SR = surface area, ft


     Q = feed flow, mgd


    C  = influent suspended solids concentration, mg/&

                                 2
    ML = mass loading rate, Ib/ft /day


     R = recycle flow, mgd

                                       2
    HL = hydraulic loading rate, gpm/ft

-------
 EM 1110-2-501

 Part 1  of  3

 29 Sep 78
     (6)  Use the larger of the two areas calculated in (5).


     (7)  Select detention time in the flotation tank and calculate the
volume .




                VOLFT = (Q + R) x  _l_      (DTFT)(106)
where



    VOLFT = volume of flotation tank, ft3


        Q = total flow, mgd


        R = recycle flow, mgd


     DTFT = detention time in flotation tank, hr


    (8)  Select pressure tank detention time and calculate volume of
pressure tank.



               VOLPT= (R) (^)(^-) (DTPT)(106)



where

                                       o
    VOLPT = volume of pressure tank,  ft


        R = recycle flow, mgd


     DTPT = detention time in pressure tank, min


    (9)  Calculate volume of sludge.



                             (Q)(C }(% removal)
                              F



where


    VS = volume of sludge ,  gpd


     Q = feed flow, mgd
                            - - _
                            (C)( specific  gravity)

-------
                                                           EM 1110-2-501

                                                             Part  1  of  3

                                                               29  Sep 78


    C  = influent suspended solids concentration,  rng/H
     o


    C  = solids concentration in float,  percent
     F


5-38.  Output Data.


    a.  Suspended solids concentration,  mg/£



    b.  Air-to-solids ratio.



    c.  Air pressure, psig.



    d.  Solids loading, Ib/ft /day.

                                 2
    e.  Hydraulic loading, gpm/ft .



    f.  Recycle flow, mgd.

                        2
    g.  Surface area, ft .



    h.  Volume of pressure tank, ft .



    i.  Volume of flotation tank, ft .



    j.  Pressure tank detention time,  min.



    k.  Flotation tank detention time,  hr.



5-39-  Example Calculations.



    a.  No Recycle.


     (l)  Select the air-to-solids ratio from Table 5-6.   A/S = 0.003



     (2)  Calculate the required pressure




                                1.3S (0.5P - 1)

                          A/S = 	
                                      C
                                       o
where



    A/S = air-to-solids ratio, 0.03

-------
 EM 1110-2-501

 Part  1 of 3

 29 Sep 78
       &  =  air  solubility at standard conditions, 18.7 cc/£


       P  =  absolute pressure, atmosphere


       Q  =  suspended solids concentration, 200 mg/£
                       00-3 = 1-3(18. 7)(0.5P - 1)
                         '            200
                                 P = 2.5
                             P =
area.
                           psig = 1U.7P - iU.7



                         psig = 1^.7(2.5) - 14.7



                                psig = 22



     ,3)  Select a mass loading rate -(Table 5-6) and calculate surface
                                (Q)(C

                           SA = -
where

                         o
    SA = surface area, ft


     Q = average flow, 1 mgd


    CQ = suspended solids concentration, 200 mg/£


    ML = mass loading, 10 Ib/ft /day
                            q,  _ 1(200)8.3*+
                               "     10

-------
                                                           EM 1110-2-501

                                                             Part  1  of 3

                                                              29  Sep  78
                             SA = 166.8 ft2
    (U)  Use SA = 167 ft2.
    (5)  Select a detention time and calculate  volume  of flotation  tank
•where


    VOUT = volume of flotation tank, ft


        Q = average flow, 1 mgd


    . DTFT = detention time, 3 hr

                                 3
     J.hQ = conversion, gal to ft


       2k = conversion, day to hr
                           vnT™ - K3) x 106
                           VOLFT -
                           VOLFT = 16,711 ft3



     (6)  Calculate volume of sludge produced.



                              Q(C  )(% removed)
                      VSP =
                            CL,( specific gravity)
                             r
where


                 VSP = volume of sludge produced, gpd


                   Q = average flow, 1 mgd


                  C  = suspended solids concentration, 200 mg/£
                   o



                                  5-U9

-------
 EM 1110-2-501
 Part 1 of 3
 29 Sep 78

            % removed = Q0%

                   CF = solids concentration in 'float,

     Specific gravity =1.05
                                  = 1(200)80
                                    5(1.05)
                              VSP = 3.QU8 gpd

     t.   With Recycle.

     (l)   Select  air-to-solids ratio,  use 0.05.

     (2)   Assume  pressure, use 50 psig.

     (3)   Calculate   P   in atmosphere.

                              P - psig +  111. 7
                                    Ik. 7

                              P = 50 + lk.7
                                    111. 7

                              P =  k.k  atm

     (k)   Calculate recycle flow.


                               1.3S (0.5P - 1)R
                         A/S =
                                   a
where

    A/S = air-to-solids ratio, 0.05

     Sa = air solubility at standard conditions, 18.7 cc/S-

      P = absolute pressure, k.k atm

-------
                                                          EM  1110-2-501
                                                            Part  1  of  3
                                                               29  Sep 78
      R = recycle flow,  mgd

      Q = average flow,  1 mgd

     C  = suspended solids concentration,  200  mg/£
      o
n n,; -  ... 5(U. U)  -
°'°5 ~
                         -
                         ~         1(200)


                              R = 0.3^3 mgd


    (5)  Select hydraulic loading and calculate  surface area.



                             qA _ (Q + R)io6
                             bA ~  HL(60)2H


where

                         2
    SA = surface area, ft

     Q = average flow, 1 mgd

     R = recycle flow, 0.3^2 mgd

                                      2
    HL = hydraulic loading, 1.5 gpm/ft

    2k = hr/day

    60 = min/hr



                            . _ (1 + 0.3U2)106
                             SA = 621.3 ft2
    (6)  Use  SA = 622 ft2 .
    (7)  Select detention time in flotation tank and calculate volume.
                                 5-51

-------
 EM 1110-2-501
 Part 1 of 3
 29 Sep 78


                        VOLFT = (Q + R)DTFT x 1Q6
                                    7.1*8(210

 where

     VOLFT = volume of flotation tank, ft3

         Q = average flow, 1 mgd

      DTFT = detention time in flotation tank, 0.5 hr

      7.1*8 = conversion factor,  gal to ft3

        24 = hr/day



                      VOLFT =  (1 +  0.3l*2)(0.5)  x  1Q6
                                     7.1*8(210 	


                            VOLFT  =  3738  ft3


    (8)   Select pressure tank detention time and calculate volume  of
pressure  tank.
                           VOTPT = R(DTPT)106
where

    VOLPT = volume of pressure tank, ft3

        R = recycle flow, 0.342 mgd

     DTPT = detention time in pressure tank, 3 min

     7-1*8 = conversion factor, gal to ft3

       2k = hr/day

       60 = min/hr
                                 5-52

-------
                          VOLPT _
                          VOLPT "
                          VOLPT = 95 ft3
    (9)  Calculate volume of sludge

                              Q(C )(% removed)
                                                          EM  1110-2-501
                                                            Part  1 of  3
                                                              29 Sep 78

                                _  0.3H2(3)106
                                "
                       VS =
                            C_( specific gravity)
                             r
where

                  VS = volume of sludge, gpd

                   Q = average flow, 1 mgd

                  C  = suspended solids concentration, 200 mg/£
                   o
           % removed = 80$

                  C  = solids concentration in float , 5$
                   F
    Specific gravity = 1.05

                             VQ - 1(200)80
                             VS ' 5(1.05)

                             VS = 30H8 gpd

 5-Uo.  Cost Data.  Appropriate cost data and economic evaluation may be
 found in Chapter 8.

 5-Ul.  Bibliography.

    a.  Burd, R. S.,  "A Study of Sludge Handling and Disposal," Publica
 tion WP-20-1*, May 1968, Federal Water Pollution Control Administration,
 Washington, D.  C.

    b.  Eckenfelder,  W. W. ,  Jr., Industrial Water Pollution Control.
 McGraw-Hill, New York, 1966.

                                  5-53

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78

    c.  Eckenfelder, W. W., Jr., Water Quality Engineering for Prac-
ticing Engineers, Barnes and Nobel, New York, 1970.

    d.  Eckenfelder, W. W., Jr., and Ford, D. L., Water Pollution
Control, Pemberton Press, New York, 1970.

    e.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection,
Treatment, and Disposal, McGraw-Hill, New York, 1972.

    f.  Roy F. Weston, Inc., "Process Design Manual for Upgrading Exist-
ing Wastewater Treatment Plants," prepared for the U. S. Environmental
Protection Agency, Technology Transfer, Oct 1971, Washington, D.  C.

    g.  Stander, G. J. and Van Vuuren, L. R. J., "Flotation of Sewage
and Waste Solids," Advances in Water•Quality Improvements - Physical
and Chemical Processes, E. F. Gloyna and W. W. Eckenfelder, Jr.,  ed.,
University of Texas Press, Austin, 1970.

    h.  U. S. Environmental Protection Agency, Technology Transfer
Seminars, "Sludge Handling and Disposal," 11-12 Dec 1973, Washington,
D. C.

    i.  Van Vuuren, L. R. J. et al., "Dispersed Air Flocculation/
Flotation for Stripping of Organic Pollutants from Effluents," Water
Research, Vol 2, 1968, pp 177-183.

    j.  Vrablik, E. R., "Fundamental Principles of Dissolved-Air
Flotation of Industrial Wastes," Proceedings, lUth Industrial Waste
Conference, 1959, Purdue University, Lafayette, Ind.
                                 5-51*

-------
                                                          EM 1110-2-501
                                                            Part 1  of  3
                                                             29 Sep 78
                  Table  5-6.   Air  Flotation  Parameters
Parameter
Air pressure, psig
Effluent recycle, %
Detention time, hr
Air-to-solids ratio
(lb air/lb solids)
Solid loading, Ib/ft2/day
Activated sludge
(mixed liquor)
Activated sludge
(settled)
Typical Value
Thickening Clarification
hO to JO itO to TO
130 to 150 30 to 120
3 0.25 to 0.5
(0.005 to 0.06)

5 to 15
10 to 20
Paragraph
(5-iti)
f
f
f,b
e,f
e
e
e
e
e
  50% primary
    +50$ activated                20 to UO                        e

  Primary only                     To 55                          e
                         r)
Hydraulic loading, gpm/ft        0.2 to it          1 to it        b,e

Detention time, min
  (pressurizing tank)              1 to 3          1 to 3        b,a
                                 5-55                (next page is 5-5T)

-------
                                                           EM  1110-2-501
                                                            Part  1  of  3
                                                              29 Sep 78

                   Section VII.   THICKENING (Gravity)

5-U2.   Background.

    a.  General.

    (l)  Thickening reduces the moisture content  of a  slurry.   Thick-
ening is used at  most waste treatment plants,  as  an ecomomic measure,
to reduce the volume of sludge or for .greater  efficiency in subsequent
processes.  Thickening is normally accomplished by gravity or  flotation
thickeners; centrifuges have also been used as sludge  thickeners.

    (2)  Gravity thickening is discussed below; air flotation  and
centrifugation are discussed under separate headings.

    b.  Gravity Thickening.

    (1)  Gravity thickening is the most common process currently used
for dewatering and for the concentration of sludge prior to digestion.
Gravity thickening is essentially a sedimentation process similar to
that which occurs in all settling tanks.  The  process  is simple and is
the least expensive of the available thickening processes.

    (2)  Gravity thickening may be classified as  plain settling and
mechanical thickening.  Plain settling usually results in the  formation
of scum at the surface and stratification of sludges near the  bottom.
Sludges from secondary clarifiers usually cannot  be concentrated by
plain settling.  Gentle agitation is usually employed to stir  the
sludge, thereby opening channels for water escape and promoting densi-
fication.  A common mechanical thickener consists of a circular tank
equipped with a slowly revolving sludge collector.  Primary and secon-
dary sludges are usually mixed prior to thickening.  A ratio of secon-
dary sludge to primary sludge of 8 to 1 or greater is recommended to
assure aerobic conditions in the thickener.  Chlorine has been used to
prevent sludge septicity and gasification which interfere with optimum
solids concentration of organic materials.  A chlorine residual of
0.5 to 1.0 mg/£ in the thickening tank overhead prevents such problems.
Organic polyelectrolytes (anionic, nonionic, and cationic) have been
used successfully to increase the sludge settling rates, the overflow
clarity, and the allowable tank loading.

    c.  Design of Thickeners.  In the design of thickeners, concen-
tration of the underflow and clarification of the overflow must be
achieved.  Mechanical thickeners (fig.  5-6) are designed on the basis


                                 5-57

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 EM  1110-2-501
 Part  1 of 3
 29  Sep 78
        CONDUIT TO MOTOR

                   A
       INFLUENT PIPE
          CONDUIT TO
        OVERLOAD ALARM
            EFFLUENT PIPE
                                                COUNTERFLOW
                                               INFLUENT WELL
                               OVERLOAD ALARM


                                EFFLUENT WEIR
                                   DIRECTION OF ROTATION
                                                         EFFLUENT CHANNEL
                                          PLAN
                      HANDRAIL
                                             TURNTABLE BASE
                                                  DRIVE
       INFLUENT PIPE
                                                   CENTER COLUMN
                                                   CENTER CAGE
                                                                 WEIR
                        STILTS

                         CENTER SCRAPER
SQUEEGEES
                                                      SLUDGE PIPE
                                      SECTION A-A
                                                  From Metcalf and Eddy, 1972
             Figure 5-6.   Schematic  of  a mechanical thickener.

of hydraulic surface  loading and solid loading.  These parameters  are
normally  obtained from laboratory batch settling tests.   Procedures
for conducting the tests  and evaluating the design parameters  are well
documented in literature  (para 5-^9c,  d,  e, f).  In  the absence  of
laboratory data, Table 5-7 may be used as a guide for  selecting  solid
                                   5-58

-------
                                                          EM  1110-2-501
                                                            Part  1  of 3
                                                               29 Sep 78
                                                                  2
loading rates.  Typical surface loading rates of 600 to 800 gpd/ft   are
recommended for most thickeners.  Hydraulic loading rates of  less than
1*00 gpd/ft2 were reported to produce odor problems (para 5-^9 h).
Detention time of the thickener may range between 2 and h hr.  Gravity
thickening is the most common method currently used at wastewater treat-
ment plants for concentrating sludges.

5-1*3.  Input Data.

    a.  Sludge flow  (Q), gpd.

    (l)  Average daily flow  (Q    ), gP
-------
EM 1110-2-501

Part 1 of 3

29 Sep 78


    C.  =  solids concentration at settling velocity  U.  ,  percent
                             p TT                     1

         =  (mg/£)  x (HT4)  -  ° °
                          H.
                               (settling test, Fig. 5-j)
                           -L                              \
C  = initial solids concentration, percent = (mg/Jl) x (lO~ )


H  = initial height, ft


H  = intercept of tangent to the settling curve, ft (Fig. 5-7)


C  = underflow concentration, percent


U  = settling velocity at the interface, ft/day (settling velocity,
     Fig. 5-7)
     UJ
     U
     <
     U.
     ir
     u
     h
     Z
     U.
     o
     H
     I
     O
     U
     I
   Figure 5-7•   Typical settling curve from laboratory test.
                              5-60

-------
                                                           EM 1110-2-501

                                                             Part 1 of 3
                                                               29 Sep~78
    "b.  Calculate mass loading.
where

                            2
    ML = mass loading, Ib/ft /day

                      p
    UA = unit area, ft /lb/day


    c.  If settling data are not available,  select mass  loading

from Table 5-7-


    d.  Calculate total surface area.
                          TSA ~


vhere

                                  2
     TSA =  total surface area,  ft


     Q     =  average daily flow,  gpd
     avg

       C  =  initial solids concentration, percent
        o
                               2
       ML =  mass loading, Ib/ft  /day


     e.  Check hydraulic loading.
                        HL =
                             Q
                        HL = -SSL  (<_800
                              O^T.

 where

                                     2
       HL = hydraulic loading, gpd/ft


     Q    = minimum flow , gpd
      mm


     Q, QY = maximum flow, gpd
      iliCLA.

                            2
       SA = surface area, ft


                                   5-61

-------
 EM 1110-2-501

 Part  1 of 3

 29 Sep 78



    f .   Select  number  of tanks  and  calculate  surface  area per tank.


                                       TKA
                                SAPT =  ±22-
                                        N

 where



    SAPT = surface  area  per tank, ft



      TSA = total  surface area,  ft2



        N = number of tanks



    g.   Select  a  detention time  (2  to  6  hr) and  calculate  tank volume.
where



       V = volume, ft



    Q    = average daily flow, gpd



       t = detention time, hr



    h.  Calculate depth.
                               D = -<-V->
                                   (SAPT)



where



       D = depth, ft



       V = volume, ft



    SAPT = surface area per tank, ft




    i.  Calculate volume of thickened sludge.



                            (Q)(C )(% recovery/100)

                      VTS = -,	r-7^	
                            (C )(specific gravity)


where



    VTS = volume of thickened sludge, gpd




                                  5-62

-------
                                                         EM 1110-2-501

                                                           Part 1 of 3
                                                            29 Sep  78



     Q = sludge flow,  gpd


    C  = initial solid concentration,  percent
     o

    C  = desired underflow concentration,  percent
     u

5-1*6.  Output Data.


    a.  Average sludge flow, mgd.


    b.  Initial concentration, percent.


    c.  Thickened concentration, percent

                           2
    d.  Mass loading,  Ib/ft /day.

                                     2
    e.  Hydraulic loading, gal/day/ft .


    f.  Detention time, hr.


    g.  Number of units.


    h.  Depth, ft.

                  3
    i.  Volume, ft .

                                 2
    j.  Surface area per tank, ft .


    k.  Volume of thickened sludge, gpd.


5-1+7.   Example Calculations.  Design of a gravity thickener is dependent

on performing laboratory batch settling tests.  Therefore, no example

calculations are presented here.


5-1*8.   Cost Data.  Appropriate cost data and economic evaluation may be

found in  Chapter 8.


5-U9.   Bibliography.


     a.  Burd,  R. S.,  "A Study of Sludge Handling and Disposal," Publica-

tion WP-20-U,  May 1968, Federal Water Pollution Control Administration,

Washington, D.  C.
                                  5-63

-------
 EM 1110-2-501
 Part 1 of 3
 29 Sep 78

     b.  Dick, R. I.,  "Thickening," Seminar on Process Design in Water
 Quality Engineering,  9-13 NOT 1970, Vanderbilt University, Nashville
 Tenn.

     c.  Eckenfelder,  ¥. ¥., Jr., Industrial Water Pollution Control.
 McGraw-Hill, New York, 1966.     ~~                        ~~	

     d.  Eckenfelder,  W. W., Jr., Water Quality Engineering for
 Practicing Engineers, Barnes and Nobel, New York, 1970.

     e.  Eckenfelder,  W. W., Jr., and Ford, D. L., Water Pollution
 Control. Pemberton Press, New York, 1970.

     f.  Edde, H. J. and Eckenfelder, W. W., Jr., "Theoretical Concept
 of Gravity Sludge Thickening," Technical Report EHE-02-6701, CRWR-15,
 1967, Center for Research in Water Resources, University of Texas,
 Austin.
    g.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection
Treatment, and Disposal, McGraw-Hill. New York, 1972.
    h.  Roy F. Weston, Inc., "Process Design Manual for Upgrading
Existing Wastewater Treatment Plants," prepared for the U. S. Environ-
mental Protection Agency, Technology Transfer, Oct 1971, Washington,
D •  L- •


    i.  U. S. Environmental Protection Agency, Technology Transfer
Seminars, "Sludge Handling and Disposal," 11-12 Dec 1973, Washington,
-U •  w •

-------
                                                          EM 1110-2-501
                                                            Part 1 of  3
                                                               29  Sep 78
        Table 5-7-  Concentrations of Unthickened and Thickened
         Sludges and Solids Loadings for Mechanical Thickeners
        Type of Sludge
Separate sludges

  Primary

  Trickling filter

  Modified aeration
  Activated

Combined sludges

  Primary and trickling filter

  Primary and modified aeration

  Primary and activated
 Sludge, Solid, percent
Unthickened    Thickened
   Solids
Loading for
Mechanical
Thickeners
 Ib/ft2/day
2.5 to 5-5
h.O to 7.0
2.0 to k.O
0.5 to 1.2
8.0 to 10.0
7-0 to 9.0
it. 3 to 7-9
2.5 to 3.3
20 to 30
8 to 10
7 to 18
h to 18
 3.0 to 6.0   7.0 to 9.0     12 to 20

 3.0 to k.O   8.3 to 11.6    12 to 20

 2.6 to k.Q   k.6 to 9.0      8 to 16
                                 5-65
                                                    From Metcalf and Eddy, 1972
                    (next page is 5-67)

-------
                                                          EM 1110-2-501
                                                            Part 1 of 3
                                                              *y  Sep  78
            Section VIII.  SEDIMENTATION (Primary Clarifier)

5-50.  Introduction.  Sedimentation is a solid-liquid separation process
designed primarily to remove the suspended particles that are heavier
than water.  This process is the most popular and the most widely used
process in waste treatment.   Sedimentation removes grit,  removes the
settleable fraction of the suspended solids from raw wastes in primary
clarifiers, separates the "biological floe from the mixed  liquor  in the
final clarifier of a biological treatment system, separates the  chemical
floe from the supernatant in physical-chemical systems, and concentrates
sludges in thickeners.

5-51.  Classification.  Sedimentation may "be classified into four
categories, depending on the characteristics of the suspension.

    a.  Discrete Settling.  Suspended solids in this case are discrete
particles which retain their identity, size, shape, and settling veloc-
ity during the settling process.  The main factor influencing the effi-
ciency of the process is the overflow rate expressed as gal/ft2/day.
All particles with settling velocities greater than the design overflow
rate will be removed.  Particles with settling velocities less than the
design overflow rate will be removed in proportion to the ratio  of their
settling velocities to the design overflow rate.   This type of settling
normally occurs in a grit chamber.

    b.  Flocculant Settling.  In this type of settling, particles floc-
culate and agglomerate during settling with changes in size, shape, and
density.  The settling velocity increases as the particles grow  larger.
The settling characteristics of the flocculant suspension can be de-
termined through laboratory settling tests.  Efficiency of removal is
influenced by both the overflow rate and the detention time.  Flocculant
settling normally occurs in a primary clarifier.

    c.  Zone Settling.  This type of settling normally occurs with acti-
vated sludge.  Particles adhere to each other and settle  as a blanket,
forming a distinct solid-liquid interface at the top of the settling
zone.  Removal efficiency is influenced by mass loading,  overflow rate,
and detention time.  Batch sedimentation tests are usually performed to
evaluate these characteristics for industrial waste suspensions.

    d.  Compression Settling.  In this case, the concentration of the
suspension is so great that the particles rest on each other at  the bot-
tom of the sedimentation basin.  This type of settling occurs in a
sludge thickener.


                                   5-67

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78

5-52.  Background.

    a.  Primary clarifiers are normally used in conjunction with
biological waste treatment systems to remove the settleable solids and
a fraction of the BOD, thereby reducing the load on the biological
systems.  Efficiently designed and operated, primary clarifiers can
remove 50 to 65 percent of the suspended solids and 25 to 35 percent
of the 5-day BOD.

    b.  Primary clarifiers are usually keyed to the overflow rates
(gal/day/ft2) and detention times.  Detention times of 2 to 3 hr,
based on average flows, are recommended.  Surface loading rates usually
depend on the characteristics of the suspension to be separated.  Batch
laboratory studies may be used to determine the optimum design param-
eters for a specific suspension.  Typical values for various suspensions
are reported in Table 5-8.  Ten State Standards (para 5-59e) recommends
a surface loading not to exceed 600 gal/day/ft2 for small plants (l mgd
or less).  Relationship of overflow rates, detention times, and tank
depths are presented in Table 5-9.

    c.  Outlet design and arrangement have been reported to affect
the efficiency of the primary clarifier.  Weir loadings, defined in the
Ten State Standards, should not exceed 10,000 gpd/ft for small plants
(1 mgd or less) and 15,000 gpd/ft for larger plants.

    d.  Primary clarifiers, rectangular or circular (fig.  5-8), are
usually cleaned mechanically.  Two tanks should be provided to allow
for maintenance and repair work.

    e.  The volume of sludge produced in primary settling tanks de-
pends on several factors which include the characteristics of the raw
waste, the design of the clarifier, the condition of the removed solids,
and the period between sludge removals (para 5-59a).  Sludge should be
removed continuously or at least once per shift (more frequently in hot
weather) to avoid deterioration of the effluent quality.  Specific
gravities of several types of sludge are shown in Table 5-10.

    f.  Primary sedimentation may be used in both biological treatment
systems and physical-chemical systems.  Figure 5-8 shows typical pri-
mary sedimentation tanks.

5-53-   Input Data.

    a.  Wastewater flow.

-------
                                                       L=LENGTH OF TANK
                                               -DRIVE SPROCKETS WITH
                                                RECESS FOR
                                                DRIVE CHAIN
                                                                                            PIVOTING FLIGHT
                                                                               2"X6" FLIGHTS SPACED APPROXIMATELY

                                                                                          JO'-O" CENTERS
V/l
 I
a\
                         HANDRAILING •
                                              DRIVE UNIT
                                                               TURNTABLE
                   BRIDGE
      SCUM TROUGH
                        SWINGING SKIMMER
                        BLADE
                        SCUM BAFFLE

                         EFFLUENT WEIR
                     /•MAXIMUM WATER
                         SURFACE
                                    PIER CAP WITH
                                    OUTLET PORTS
      EFFLUENT
       LAUNDER
                                                               INFLUENT
                                                                BAFFLE
                        3 DIAM
                      SCUM PIPE
-SKIMMER
SUPPORTS*-
                                  CENTER PIER AND

                                INFLUENT RISER PIPE
                     SIDE WATER
                       DEPTH
                                             DRIVE CAGE

                                               TRUSSED RAKE
                           1-1/2" BLADE
                           CLEARANCE
        ADJUSTABLE
        SQUEEGEES
2" GROUT



      SLUDGE DRAW-OFF PIPE
TOP OF GROUT
   AT WALL
                                                                 INFLUENT PIPE
                                                                                             From Metcalf and Eddy, 1972

                        Figure  5-8.   Schematics of typical primary sedimentation tank.
                                                                                                         vod-

                                                                                                         W H

                                                                                                         "O O


                                                                                                         00 U)
                                                  H
                                                  O
                                                  I
                                                  ro
                                                  I
                                                  vn
                                                  O

-------
EM 1110-2-501
Part 1 of 3
29 Sep  78
     (l)  Average flow, mgd.

     (2)  Peak flow, mgd.

    b.  Suspended solids, mg/£.

    c.  Volatile suspended solids, percent.

    d.  BOD  concentration, mg/£.

5-5^.  Design Parameters.
                             2
    a.  Overflow rate, gpd/ft  .  See Tables 5-8 and 5-9.

    b.  Detention time, hr.  See Table 5-9.

    c.  Specific gravity of sludge.  See Table 5-10.

    d.  Solids content of underflow, percent (h to 6 percent).

    e.  Removal efficiencies.

    (l)  Suspended solids, percent.  See Figure 5-9.

    (2)  BOD , percent.  See Figure 5-10.
            J
    f.  Weir loading, gpd/ft (10,000 to 15,000 gpd/ft).

5-55-  Design. Procedure.

    a.  Select an overflow rate by using Table 5-8 or by laboratory
methods and calculate surface area.
                              SA =
                                      x 106
                                     OFR

where
                          2
     SA = surface area, ft

     Q  = peak flow, mgd

    OFR = overflow rate, gal/ft2/day

                                 5-70

-------
 I
—3
H1
             H-
            cw
             I
            VO
                                                                    SUSPENDED SOLIDS REMOVAL. %
                                                                                                                                                                  Ni  i-j H
                                                                                                                                                                  VO  ct- M
                                                                                                                                                                  (0      IX)
                                                                                                                                                                 •u   o  i
                                                                                                                                                                      *-b vn
                                                                                                                                                                  ^i     o
                                                                                                                                                                  00  U) H

-------
 EM 1110-2-501

 Part 1 of 3
 29 Sep 78
   60
   40
J«

J


O

Ul
o:

Q
O
m
  20
   3000                 ,000                             500	
                SETTLING RATE, GPD/SQ FT TANK AREA (DESIGN FLOW)



          Figure  5-10.   BOD removal rate in primary clarifier.




    t>.  Select detention time  and calculate volume (see Table  5-9).
                                 400
                       =  (Qavg)(t)
where
       V = volume of tank,  ft
    Q    = average  flow, mgd


       t = t iaie , hr


    c.  Calculate side water depth.
                                 SWD =
JL
SA
                                  5-72

-------
                                                           EM 1110-2-501

                                                             Part 1 of 3
                                                               29 Sep 78
vhere
    SWD = side water depth, ft


      V = volume, ft3

                          2
     SA = surface area, ft


    d.  Check solid loading rate.
                              (Q  J(SSI)(8.3M
                                     (SA)



where

                                    2
     SLR = solid loading rate, lb/ft /day


    Q    = average flow, mgd
     avg

     SSI = influent solids concentration,  mg/£

                           2
      SA = surface area, ft


    e.  Select weir loading rate and calculate weir length.





                             WL = Ikx lo6



where


     WL = weir length, ft


     Q  = peak flow, mgd


    WLR = weir loading rate, gal/ft/day


    f.  Determine percentage of suspended  solids removed from Figure 5-9•


    g.  Calculate amount of primary sludge produced.
                                 5-73

-------
 EM 1110-2-501
 Part 1 of  3
 29 Sep 78


                   PSP = (Q   )(SSI)(SSR)(10~2)(8.3>0


where

     PSP = primary sludge produced, Ib/day

    Q    = average flow, mgd

     SSI = influent solids concentration, mg/£

     SSR = suspended solids removed, percent (50 to 60 percent for
           municipal systems)

    h.   Select underflow concentration (3 to 6 percent) and sludge
specific gravity (Table 5-10), and calculate the volume flow of primary
sludge produced.


                  VPSP = 	PSPUQO}	
                         (specific gravity )(UC)(8. 3M


where

    VPSP = volume flow of primary sludge produced, gal/day

     PSP = primary sludge produced, gal/day

      UC = underflow concentration (3 to 6 percent)

    i.  Determine BODR in primary clarifier (25 to 35 percent in mu-
nicipal systems), or select BODR from Figure 5-10, and calculate primary
effluent characteristics.
SSE = (SSI)II
                                        SSR\
                                        100 /
                        BODE = (BODl)l -
where

     SSE = primary effluent suspended solids, mg/£

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
     SSI = influent solids concentration,  mg/£


    BODE = primary effluent BOD,  mg/£


    BODI = influent BOD,  mg/£


    BODE = BOD removal in primary clarifier, percent


5-56.  Output Data.

                             2
    a.   Overflow rate, gal/ft /day.

                        2
    "b.   Surface area, ft  .


    c.   Side water depth, ft.


    d.   Detention time, hr.

                            2
    e.   Solid loading, It/ft /day.


    f.   Weir loading, gal/ft/day.


    g.   Weir length, ft


    h.   Volume of sludge produced, gal/day.


    i.   Suspended solids removal, percent.


    3.   BOD removal, percent.


    k.   COD removal, percent.


    1.   TKN removal, percent.


    m.   PO, removal, percent.


    n.   Effluent BOD, mg/&.


    o.   Effluent suspended solids, mg/£.


    p.   Effluent COD, mg/£.


    q..   Effluent TKN, mg/£.
                                  5-75

-------
EM 1110-2-501

Part 1 of 3


 29 Sep  78




5-57-  Example Calculations.



    a.   Select an overflow rate and calculate surface area.
                             SA =
                                     x 106
                                    OFR
where


                          2
     SA = surface area, ft



     Q  = peak flow, 2 mgd



    OFR = overflow rate, 600 gpd/ft2
                              SA= 2 x

                              SA
                                     600
                              SA = 3333 ft2
    "b.  Select detention time and calculate volume.





                                Q    t x 10
                            v = ^yg
where


                     ^

       V = volume, ft




    Q    = average flow, 1 mgd




       t = detention time, 2.4 hr


                                       o

    7.^8 = conversion factor, gal to ft




      24 = hr/day








                                  5-76

-------
                             V =




                             V = 13,369 ft3



    c.   Calculate side water depth.
where
    SWD = side water depth, ft


      V = volume, 13,369 ft3

                               2
     SA = surface area, 3333 ft



                                  _ 13,369
                              SWD = H.O ft



    d.  Check solids loading rate.



                                Q   (SSI)8.3U
                                      SA



where

                                     2
     SLR =  solids loading rate, It/ft /day


     0    =  average  flow, 1 mgd
     avg

     SSI =  influent suspended solids, 200


     8.3*1 =  conversion  factor, mg/£  to Ib/million  gal

                                2
       SA =  surface  area, 3333 ft



                                  5-77
                                                            EM 1110-2-501
                                                              Part  1  of 3
                                                               29 Sep  78

-------
 EM 1110-2-501
 Part 1 of 3
 29 Sep 78


                           gLR  =  1(200)8.31+


                           SLR  =  0.5  Ib/ft2/day

     e.  Select weir loading rate and calculate weir length.


                             WL = SL- x 106

where

     WL = weir length, ft

     Q  = peak flow, 2 mgd

    WLR = weir loading rate, 6000 gpd/ft


                               _ _2	    6
                                 6000  X 10

                            WL = 333 ft


    f.  Determine percentage of suspended solids removed.  SSR = 60%.

    g.  Calculate amount of primary sludge produced.


                      PSP = Qavg(SSl)SSR(lO~2)8.3l+

where

     PSP = primary sludge produced,  Ib/day

    Qavg = averaSe flov,  1 mgd

     SSI = suspended solids concentration, 200 mg/i

     SSR = suspended solids removed,


                                 5-78

-------
                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                               29 Sep 78
       f^

    10~  = conversion factor,  % to decimal



    8.3^ = conversion factor,  mg/£ to Ib/million  gal





                       PSP = 1(200)(60)10~2(8.3M
                      J1



                       FSP = 1000 Ib/day




    h.  Select underflow concentration and  sludge specific gravity and

calculate the volume flow of primary sludge produced.




                   VPSP =	PSP (IPO?

                   VFb^   (specific gravity)UC(8.3U)




where



                VPSP = volume flow of primary sludge  produced, gal/day



                 PSP = primary sludge produced,  1000  gpd



                 100 = conversion factor, % to decimal



    Specific gravity =1.03



                  UC = underflow concentration,  3%



                Q.3h = conversion factor, mg/£ to !b/million gal





                           VPSP =  1000(100)
                                  1.03(3)8.3H




                           VPSP = 3880 gpd




    i.  Select BODR and calculate primary effluent characteristics.





                          SSE = SSI




                             _      /    BODR}
                        BODE - BODI^l - 10Q  J





                                  5-79

-------
 EM 1110-2-501
 Part 1 of 3
 29 Sep 78

 where

      SSE = effluent  suspended solids,  mg/£

      SSI = influent  suspended solids,  200 mg/H

      SSE = percent removal  suspended solids,  60$

     BODE = effluent  BOD, mg/2,

     BODI = influent  BOD, 200  mg/£

     BODR = percent removal  of BOD, 36%
                          SSE = 200
                                         100 /

                          SSE = 80 mg/l,


                          BODE = 200  ll	36.]

                          BODE = 128 mg/A


5-58.  Cost Data.  Appropriate cost data and economic evaluation may
be found in Chapter 8.

5-59.  Bibliography.

    a.  American Society of Civil Engineers and the Water Pollution
Control Federation, "Sewage Treatment Plant Design," Manual of Practice
No. 8, 1959, 1961, 1967, 1968, Water Pollution Control Federation,
Washington, D. C.

    b.  Burns and Roe, Inc., "Process Design Manual for Suspended
Solids Removal," prepared for the U.  S. Environmental Protection Agency,
Technology Transfer, Oct 1971, Washington,  D.  C.

    c.  Camp, T. R., "Sedimentation and the Design of Settling Tanks,"
Transactions, American Society of Civil Engineers, Vol 111  Part III
inl-6, pp 895-952.

    d.  Gulp, G. L., Hsuing, K.,  and Conley,  W.  R., "Tube Clarification


                                 5-80

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep  78

Process, Operation Experience," Journal, Sanitary Engineering Division,
American Society of Civil Engineers, Vol 95, SA5, 1969, PP 829-8H8.

    e.  Great Lakes-Upper Mississippi River Board of State Sanitary
Engineers, "Recommended Standards for Sewage Works (Ten States Stan-
dards)," 1971, Health Education Service, Albany, N.  Y.

    f.  Hansen, S. P., Gulp, G. L. , and Stukerberg,  J.  R. , "Practical
Application of Idealized Sedimentation Theory in Wastewater Treatment,"
Journal, Water Pollution Control Federation, Vol hi, Aug 1969, PP
    g.  McLaughlin, R. T. , "The Settling Properties of Suspensions,"
Journal, Hydraulic Division, American Society of Civil Engineers, Part I,
Paper No. 2311, Vol 85, No. HY12, 1959, PP 9-^1-

    h.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection,
Treatment, and Disposal, McGraw-Hill, New York, 1972.

    i.  Wallace, A. T. , "Design and Analysis of Sedimentation Basins,"
Proceedings, Sixth Annual Sanitary and Water Resources Engineering
Conference, Technical Report No. 13, 1967, PP 119-128,  Department of
Sanitary and Water Resources Engineering, Vanderbilt University, Nash-
ville, Tenn.
                                  5-81

-------
 EM 1110-2-501
 Part 1 of 3
 29 Sep 78
              Table  5-8.   Recommended Surface-Loading Rates
                          for Various Suspensions
     Suspension
Untreated wastewater
Alum floca
                               Range
                                                                  r
                                             Loading Rate, gpd/ft'
Iron- floe'
Lime floe
a
600 to 1200
360 to 600
5kO to 800
5^0 to 1200
Peak Flow
  1200
   600
   800
  1200
   Mixed with the settleable  suspended solids in the untreated waste-
  water and colloidal or other  suspended solids swept out by the floe.
                                                   From Met calf and Eddy, Inc., 1971
                 Table 5-9.  Detention Times for Various
                  Surface-Loading  Rates and Tank Depths
Surface-Loading
o
Rate, gpd/ft
1*00
600
800
1000

7-ft
Depth
3.2
2.1
1.6
1.25
Detention
8- ft
Depth
3.6
2.U
1.8
1.1*
Time, hr
10-ft
Depth
U.5
3.0
2.25
1.8

12-ft
Depth
5.U
3.6
2.7
2.2
                                                   From Met calf and Eddy, Inc., 1971
               Table 5-10.  Specific Gravity of Raw Sludge
                  Produced from Various  Types of Sewage
Type of
Sewerage System
Sanitary
Sanitary
Combined
Combined
Strength
of Sewage
Weak
Medium
Medium
Strong
Specific
Gravity
1.02
1.03
1.05
1.07
From Met calf and Eddy, Inc., 1971
                                 5-82

-------
                                                           EM 1110-2-501
                                                             Part  1  of  3
                                                              29  Sep 78

            Section IX.   SEDIMENTATION (Secondary Clarifier)

5-60.  Background.

    a.  The final clarifier performs a vital role in a secondary waste
treatment system.  In the activated sludge process,  the final clarifier
must provide an effluent low in suspended solids and an underflow  of
sufficient concentration to maintain a sufficient population  of  active
microbial mass in the aeration tank.  Final clarifiers are, therefore,
designed to provide clarification, as well as thickening.

    b.  In addition to being governed by the overflow rate and detention
time, the design of final clarifiers must be based on solid loading
rates (ib solids/ft2/day).  Surface overflow rates and detention times
recommended by the Ten State Standards (para 5-6?f)  are presented  in
Table 5-11.  Typical values of overflow rates recommended for the  design
of secondary clarifiers include 600 gal/ft2/day for  smaller plants (up
to 1 mgd), and up to 800 gal/ft2/day for larger plants.  The  design
calculations should consider the peak incoming wastewater flow;  the  re-
turn sludge flow rate is not included since, in most secondary clari-
fiers, the return sludge withdrawal takes place at a point very  near
the inlet to the tank.  Solids loading rates for various mixed liquor
suspended solids are illustrated in Figure 5-11.  Typical solids load-
ing rates reported range from 12 to 30 Ib/ft2/day.  Solid concentration
of the underflow ranges from 0.8 to 1.20 percent, by weight.

    c.  The performance of the final clarifiers is also affected by the
method of sludge withdrawal.  The preferred sludge collection mechanism
is a vacuum- or  suction-type draw off (para 5-67b).   The plow-type
collectors with the chain and flight mechanism in rectangular basins
or the bridge with attached plows in circular basins ineffectively con-
centrate the waste activated sludge.

     d.  The bibliography  (para 5-67) contains excellent discussions on
the  design and operation of final clarifiers.

5-6l.  Input Data.

     a.  Wastewater flow.

     (l)  Average daily  flow, mgd.

     (2)  Peak flow, mgd.
                                  5-83

-------
 EM 1110-2-501
 Part 1 of 3
 29  Sep  78
TE BASED ON MIXED-
OW, GPD/SQ FT
b b
< -1
> C 500
0°
ulO'
U-1
o
100


-LIMI
O












- - • — — ^__

TING PEAK OVERFLOV
N PLANT FLOW (1,200
-WITH 50 PERCENT RE












^
v
V





too
\\
-\-
^0 \


^ R/I
GPC
:CY




TE BA!
)/SQ FT
3LE)M
M


<^<£>f, ••%•
*«j£^

^
i
11

\
1.OOO
^S*
N s
V >
S,
V
S
s



>ED -
< - - •
31^
s S
•.
••

                          MIXED-LIQUOR SUSPENDED-SOLIDS
                            CONCENTRATION, MG/LITER
                                                     10,000
                  Figure 5-11.  Solids loading rates  for
                  various mixed liquor suspended solid
                             concentrations .
b.
        Mixed liquor suspended solids, mg/£.
5-62.   Design Parameters.
                   rate
                                         (from Fig. 5-11)
    b.   Surface overflow rate.

    (1)   Small plants <_600 gal/ft2/day.

    (2)   Larger plants <800 gal/ft2/day.

    c.   Sludge specific gravity from Table 5-10.

    d.   Underflow concentration (UC), percent.

    (1)   For activated sludge   UC =  0.8-1.2 percent.

    (2)   For trickling filter   UC =  2-k percent.


                                 5-84

-------
                                                           EM 1110-2-501

                                                             Part 1 of 3
                                                               29 Sep 78
    e.   Weir overflow rate = 10,000-15,000 gpd/ft/day.


    f.   Detention time = 2-h hr.


5-63.   Design Procedure.


    a.   Select a solids loading rate (fig. 5-11) and calculate the

surface area.


                             (Qav )(MLSS)(8.3U)


                        SA =   ^ SLR



where

                           2
      SA = surface area, ft


    Q    = average flow, mgd
     avg

    MLSS = mixed liquor suspended solids, mg/fc

                                    2
     SLR = solid loading rate, Ib/ft /day


    t>.  Check the maximum overflow rate.


                                   Q^ x 106

                             OFR =
                                      SA



where

                                       2
     OFR = maximum  overflow rate,  gal/ft /day


        S= peak  flow, mgd

                          2
     SA = surface  area, ft


If  OFR  is within range, proceed to next  step;  if   OFR   is  outside

range, assume   OFR and recalculate  SA  as follows.


                                    Q   x 10


                               SA =  OFR




     c.  Assume  detention  time and calculate volume.



                                   5-85

-------
 EM 1110-2-501
 Part 1 of 3
 29 Sep 78
 where

        V = volume ,  ft

     Sivg = averase  daily flow,  mgd

        t = detention time,  hr

     d.   Calculate side  water  depth.
where

    SWD = side water depth, ft

      V = volume, ft
                          p
     SA = surface area, ft

    e.  Select weir overflow rate and calculate weir length.

                                   Q  x io6
                              WL = -£ -
                                     WOFR

where

      WL = weir length, ft

      Q  = peak flow, mgd

    WOFR = weir overflow rate, gal/ft/day

5-6U.   Output Data.

    a.   Solids loading rate, Ib/ft2/day.
                        o
    b.   Surface area, ft .

    c.   Overflow rate, gal/ft2/day.

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                             29 Sep 78


    d.   Detention time,  hr.


    e.   Weir overflov rate,  gal/ft/day.


    f.   Tank side water  depth,  ft.


    g.   Weir length,  ft.

    h.   Volume of wasted sludge,  gal/ day.


    i.   Underflow concentration,  percent.


    j.   Effluent total BOD,  mg/fc.


5-65.  Example Calculations.

    a.   Select a solids  loading rate and calculate the surface area.


                               Q
                                    SIK

where

                           2
      SA = surface area, ft


    0    = average flow, 1 mgd
     avg

    MLSS = mixed liquor suspended solids, 3000 mg/£

                                        2
     SIR = solids loading rate, 15 It/ft /day


    8.3k - conversion factor, mg/& to lb /million gal.


                           OA   1(3000)8.3*+
                             SA = 1668 ft2
    b.  Check the maximum overflow rate.


                                   Q  x ic6
                             OFR = _£ _
                                      SA


                                 5-87

-------
 EM 1110-2-501
 Part 1 of 3
 29 Sep 78

 where


     OFR = maximum overflow rate, gal/ft2/day

      Q  = peak  flow,  2 mgd

      SA = surface area, 1668 ft2


                             rwp - 2 x IP6
                             °FR -  1668

                         OFR = 1199 gal/ft2/day

 This  value  is excess; therefore, redesign on  OFR = 1000 gal/ft2/day.

                                   Q  x io6

                              SA =   OFR


                                 = 2 x lo6
                                    1000

                             SA = 2000 ft2
                                Q
                          SLR =
                                      SA


                               - 1(3,000)8.3^
                               --     -
                          SLR = 12.5 lWft2/day

    c.  Assume detention time and calculate volume.


                                 Q   (t)!06
                             V =
where

                             Q
       V = volume of tank, ft


    Q    = average flow, 1 mgd
     ^ " o

       t = detention time, 2.5 hr




                                 5-88

-------
     .U8 = conversion factor,  gal to ft

      2h = hr/day

                             v _ 1(2.3)10'
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
                                       3
                             V = 13,926 ft3

    d.  Calculate side water depth.
vhere
    SWD = side water depth, ft

      V = volume, 13,926 ft3
                                2
     SA = surface area, 2,000 ft
                              SWD = T.O ft

    e.  Select weir overflow rate and calculate weir length.

                                  Q^ x 10
                             WL =
                                    WOFR

where

      WL = weir length, ft

      Q  = peak flow, 2 mgd

    WOFR = weir overflow rate, 10,000 gal/ft/day
                              WL -
                                   10,000


                              WL = 200 ft


                                 5-89

-------
 EM 1110-2-501
 Part 1 of 3
  29 Sep  78


 5-66.  Cost Data.  Appropriate cost data and economic evaluation may be
 found in Chapter 8.

 5-67.  Bibliography.

     a.   Burns and Roe, Inc., "Process Design Manual for Suspended Solids
 Removal,  prepared for the U.  S.  Environmental Protection Agency  Tech-
 nology Transfer, Oct 1971, Washington, D.  C.

    b.   City of Austin, Texas, "Design Guides for Biological Wastewater
 Treatment Processes," Report No.  11010ESQ,  Aug 1971,  U.  S.  Environmental
 Protection  Agency,  Washington, D.  C.

    c.   Dick,  R.  I., "Fundamental Aspects of  Sedimentation  2," Water and
 Wastes Engineering. Vol 6, No.  3,  1969,  pp  kh-h^.               	

    d. Dick,  R.  I., "Thickening,"  Advances  in Water Quality Improve-
 ments -  Physical and^ Chemical  Processes. B. F.  fvinvr,..  an* T.T  T/ F^n
 felder,  Jr.,  ed., University of Texas  Press,  Austin, Texas,  1970.

    e.   Eckenfelder,  W.  W.,  Jr., and  O'Connor,  0.  J.,  Biological Waste
 Treatment, Pergamon Press,  New York,  1961.             	 	~~

    f.   Great Lakes-Upper Mississippi  River Board  of State  Sanitary
 Engineers,  Recommended Standards  for  Sewage  Works  (Ten  States  Stan-
 dards;,   1971, Health  Education Service, Albany, N. Y.

    g.  McLaughlin,  R.  T.,  "The Settling Properties of Suspensions "
 Journal.  Hydraulic  Division. American  Society of Civil Engineers  Part  I
 Paper No. 2311, Vol  85, HY12, 1959, PP 9-1*1.          "   	'

    h.  Metcalf and Eddy, Inc., Wastewater Engineering;  Collection
 Treatment, and Disposal. McGraw-Hill, New York, 1972.   	'

    i.  Rex Chainbelt,  Inc., "A Mathematical Model of  a  Final Clari-
 fier,   Report No. 17090FJW, Feb 1972, U. S.  Environmental Protection
Agency, Washington, D.  C.

    J.  Wallace, A.  T., "Design and Analysis of Sedimentation Basins,"
Proceedings, Sixth Annual Sanitary and Water Resources Engineering Con-
ference»  Technical Report No. 13,  1967, pp 119-128, Department of Sani-
tary and Water Resources Engineering, Vanderbilt University, Nashville
Tenn.                                                                  '
                                 5-90

-------
                      Table 5-11.   Design Requirements for Final Settling  Tanks
v_n
VQ

Type of Process
Conventional, modified, or
"high rate" and step aeration
Contact
stabilization
Extended aeration
Average Design
Flow, mgd
To 0.5
0.5 to 1.5
1 . 5 and up
To 0.5
0.5 to 1.5
1.5 and up
To 0.05
0.05 to 0.15
0.15 and up
Detention
Time , hr
3.0
2.5
2.0
3.6
3.0
2.5
U.O
3.6
3.0
Surface
Settling Rates
gal/day/ft2
600
TOO
800
500
600
TOO
300
300
600
0>
X
ct-
p>
tw
vo
u>
   Note:  The inlets and sludge collection and withdrawal facilities  shall be designed
to minimize density currents and assure rapid return of sludge to  the aeration tanks.
Multiple units capable of independent operation are desirable and  shall be provided in
all plants where design flows exceed 0.1 mgd unless other provision is made to assure
continuity of treatment.
   The detention time, surface settling rate, and weir overflow  rate  should be adjusted
for the various processes to minimize the problems with sludge loadings, density cur-
rents  inlet hydraulic turbulence, and occasional poor sludge settleability.
      '                                                              From Ten States Standards, 1971
10
                                                                                                •g

                                                                                                     E
                                                                                                     M
                                                                                                     '
  O I
  HI vn

-------
                                                         EM 1110-2-501
                                                           Part 1 of 3
                                                              29 Sep  78

                         Section X.   FILTRATION

5-68.  Background.

    a.  Filtration is the removal of suspended solids through  a porous
medium.  Until recently, filtration was used mainly in water treatment
to remove suspended solids and bacteria.  However,  the increasing  con-
cern for abatement of water pollution and the requirements  for high
quality effluents from wastewater treatment facilities have resulted  in
the rapid, wide acceptance of filtration in wastewater treatment.  Fil-
tration is "being used for the removal of biological floe from  secondary
effluents, phosphate precipitates from phosphate removal processes, and
as a tertiary wastewater treatment operation to prepare effluents  for
reuse in industry, agriculture, and recreation.

    b.  Granular media used in filtration include sand, coal,  crushed
anthracite, diatomaceous. earth, perlite, and powdered activated carbon.
Sand filters have been mostly used in water treatment.  These  filters
are classified into slow sand filters and rapid sand filters.

    c.  Slow sand filters are normally 12-30 in. deep.  The sand rests
on a layer of gravel which, in turn, rests on an underdrain system.   The
filter is usually operated at a rate of 3 gal/ft2/hr.  When the filter
becomes clogged, it is normally deactivated, drained, allowed to par-
tially dry, and the surface layer of sludge is manually removed.   Since
slow  sand filters require large space, have high maintenance costs,  and
clog rapidly, their application to water treatment has been abandoned;
their application to wastewater treatment has been very limited.   Design
and operational characteristics of slow sand filters are summarized in
Table 5-12.

    d.  Rapid sand filters consist of a layer of sand 18-30 in. thick
supported by a layer of  gravel 6-l8  in. thick and an underdrain system.
The underdrain system not only supports the sand, but also collects the
filtered water and distributes the backwash water.  The gravel aids in
the distribution  of the  wash water while preventing the loss of filter
media to the underdrain.  Rapid sand filters are usually operated at a
rate  of 2 gal/ft2/min.   The filters are cleaned by backwashing.  Nor-
mally, the filter is backwashed when the head loss increases to a value
approaching the actual head available or when the effluent•quality be-
gins  to deteriorate.  The length of time of filter runs normally depends
on the quality of the feed water.  The  common rate of backwashing is
2^-30  in./min (about 15  gal/ft2/min) for 3-10 min.  This rate results in
about  30 percent  expansion of the  sand.


                                  5-93

-------
 EM 1110-2-501
 Part 1 of 3
 29 Sep 78

     e.   Rapid sand  filters  (fig.  5-12) are usually constructed in dupli-
 cate.   The filters  are commonly arranged in rows along one or both sides
 of a pipe gallery.  Total depths  of filters from water surface to under-
 drains range  from 8 to 10 ft.  A  length-to-width ratio of the filter t>ox
 of 3 to 6 has been  found most economical.  Wash water gutters must be
 located so that they limit the horizontal travel of dirty water during
 backwashing to 3 ft.  As a  safety factor, the top edge of the backwash
 gutter is normally  located 6-12 in. above the allowed expansion of the
 sand (usually 50 percent).  Backwash gutters must -be designed to carry
 all backwash  water  with a minimum 3-in. free fall at the upper end.  The
 underdrain system must be designed to carry the backwash water and to
 provide uniform distribution of backwash water.  Some rules of thumb
 that have been used in the design of pipe lateral underdrain systems are
 shown in Table 5-13.  Filter piping, design flows, and velocities are
 presented in  Table  5-lU.  Design  and operational characteristics of
 rapid sand filters  are shown in Table 5-12.  Typical gravel bed for pipe
 underdrain system is shown in Table 5-15.

     f.   The removal of surface material by sand filters leaves a heavy
 residue of removed  solids on the  raw water side of the filter medium.
 Surface filtration  is extremely sensitive to suspended solids concentra-
 tion in the feed water.  Sand filters may quickly become clogged at the
 surface,  resulting  in an extremely short filter run,  thereby limiting
 the  practical  application of sand filters in wastewater treatment.

     g.   One method used to increase the effective depth of filtration
 involves  the use of dual-media or multimedia beds.   The filters are com-
 posed of  two or three materials of different specific gravities and
 sizes.  The coarsest and lightest materials are placed on top; the  fin-
 est  and heaviest materials are on the bottom.   An anthracite/sand filter
 is an example  of a dual-media filter.   Typical anthracite/sand filters
may  include from 12 to 2k in.  of anthracite (specific gravity, l.U-1.6)
 and  6 to  16 in. of sand (specific gravity,  2.65).   Multimedia filters
 normally  consist of anthracite placed on top of sand  which is placed on
 top  of  garnet.  Typical design data for dual-media and multimedia fil-
ters are  presented in Table 5-l6.

    h.  Another innovation introduced into  filtration is  the  mixed  media
 concept.  For this process,  the size distribution of  the  different  media
is selected to ensure intermixing between the  various media at the  inter-
 faces.  This mixing will prevent the formation of an  impervious layer at
the  interface during filtration.   A typical mixed dual-media  filter may
consist of 12 in.  of sand with an effective size of 0.5-0.55  mm and a
uniformity coefficient of less than 1.65, and  12 in.  of crushed

-------
                                                             EM 1110-2-501
                                                               Part  1 of 3
                                                                 29 Sep  78
                                                                   LATERALS
                                                     FILTER TO WASTE
                                                    WASH OUTLET HEADER
                                                  WASH-WATER INLET HEADER
                                           PIPE GALLERY FLOOR
                               CLEAR WELL
                                    a.
                    WASH TROUGH
PERFORATED LATERALS

 FILTER FLOOR
CAST IRON MANIFOLD
WITH STRAINERS IN TOP
                                                     FILTER TANK
                               b.

       Figure  5-12.  Schematics of typical rapid sand  filters.
                                  5-95

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 EM 1110-2-501
 Part  1  of  3
 29  Sep  78

 anthracite coal with an effective size of 0.9-1.0 nun and a uniformity
 coefficient  of less than 1.8.  A typical mixed multimedia filter has a
 particle size gradation that decreases from about 2-mm anthracite at the
 top to  about 0.15-mm garnet at the bottom.  Information concerning vary-
 ing mixed  media designs for various types of floe removal is presented
 in  Table 5-17-  The filter piping is usually designed for the flows and
 velocities shown in Table 5-l8.

    i.  A  mixed-media design typically used for removal of moderate
 quantities of chemical floe requires a backwash rate of about 15 gpm/ft2.
 The head loss through the expanded filter is 2-b ft.  The required dura-'
 tion  for backwash water is typically 2-5 percent of the plant throughput.
 Surface wash is also necessary to break up the clumps.   Normally, sur-
 face wash  is initiated 1 min before the main backwash starts and is
 stopped about 1 min prior to the end of the backwash.

    J.  In conclusion,  the design of filters depends on the influent
wastewater characteristics, process and hydraulic loadings, method and
 intensity  of cleaning,  nature,  size, and depth of the filtering material,
 and the required quality of the final effluent.   In general,  mixed dual-
media and multimedia filters are more effective and easier and less ex-
pensive to operate than sand filters for the treatment  of wastewaters;
therefore,  they are more widely accepted in wastewater  treatment.  The
design of a multimedia  filter is illustrated below.   However, the proce-
dure can be applied to  the design of a rapid sand filter also.

5-69.   Input  Data.

    a.  Wastewater characteristics.

    (l)   Average daily  flow,  mgd.

    (2)   Peak flow,  mgd.

    b.  Suspended solids,  mg/£.

    c.  Suspended solids  characteristics.

    (l)   Biological  floe.

    (2)   Chemical  floe.

    (a)   Alum dose.
                                  5-96

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                                                          EM 1110-2-501
                                                            Part 1 of 3
                                                               29 Sep  78
    (b)   Lime  dose.


    (c)   Ferric  chloride.


    d.   Temperature,  °F.


    e.   Alkalinity.


    f.   pH.


5-70.   Design  Parameters.

                                                  2
    a.   Rate of wastewater application,  gal/min/ft .


    b.   Size distribution  of filter media,  mean diameter,  mm.


    c.   Approach velocity, fps.


    d.   Number of layers.


    e.   Shape  factor for each layer.


    f.   Porosity of unexpanded bed depth.


    g.   Specific gravities of filter medium and of water.


    h.   Depth  of each filter medium, ft.


    i.   Permeability of each layer.


    J.   Size distribution of gravel.


    k.   Depth of gravel medium, ft.


    1.   Desired degree of bed expansion (20-50 percent).


    m.   Type of underdrain system.


    n.   Head loss in underdrain system, ft.


    o.   Diameter of 60 percentile particles, d,-_, mm.

                                      2
    p.   Specific weight of sand, Ib/ft  .
                                 5-97

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EM 1110-2-501
Part 1 of 3
29 Sep  78
                                2 ,  k
    q.  Density of water, Ib-sec /ft .

    r.  Absolute viscosity of water, centipoises.

    s.  Porosity of expanded bed.

    t.  Number of troughs.

    u.  Width of trough, ft.

    v.  Depth of underdrain, ft.

    w.  Operating depth of water above sand, ft.

    x.  Freeboard, ft.

    y.  Time of backwash, min.

    z.  Distance from top of trough to underdrain, ft.

5-71-  Design Procedure.

    a.  Select a loading rate (filtration rate) and calculate filter
surface area (Table 5-l6).


                                  Q   (106)
                             "" ~ LR(2U)(60)

where
                           2
      SA = surface area, ft

    Q    = average flow, mgd
                                   2
      LR = loading rate, gal/min/ft

    b.  Select filter medium and evaluate size distribution and depth of
each layer (Tables 5-12 and 5-l6).

    c.  Calculate terminal head loss through filter using Kozeny
equation.
                                  5-98

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                              29 Sep 78
hf_ /v\
LI /
\ g /
(1 - £
:)2"
£3
(v/Sf/
ld jl
\P/ V
1
,3.28 x io~3x
where


             h  = loss of head in depth of "bed, ft


              L = length, ft


              K = coefficient of permeability, ^

                                         2
              v = kinematic viscosity, ft /sec

                                                    2
              g = gravitational acceleration, ft/sec


              £ = porosity of layer


              v = approach velocity, fps


             a  = shape factor = (6 for spherical, 8.5 for crushed

                  granules)


             d  = mean particle size, mm

             _o
    3.28 x 10   = conversion factor, mm to ft


    d.  Calculate unit head loss through each expanded media.
                       Ap = D(l - e)(G    - G   )
                                      s,m    s,w
where


      Ap = pressure drop across fluidized bed, ft


       D = unexpanded bed depth, ft


       e = porosity of unexpanded media


    G    = specific gravity of filter medium
     s 9 in



                                 5-99

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EM 1110-2-501
Part 1 of  3
29 Sep 78

    G    = specific gravity of water

    e.   Calculate total head loss through expanded media.


                               (Ap)T = EAp


where

    (Ap)   = total pressure drop across fluidized bed, ft

    f.   Calculate rate of filter backwashing for any desired expansion
using the  Amirtharajah method (para 5-75a) as follows.

    (l)  Calculate minimum fluidization velocity.


                                ) ' 2  fw (W  - W )~|°'9
                                	L s  m    s J	
                v
                 f                  0.88
                                   y

where
                                               2
     v_ = minimum fluidization velocity, gpm/ft

    dg0 = 60 percent finer size of the sand, mm, s=0.75

     W  = specific weight of water, Ib/ft
      s
                                        o
     W  = specific weight of sand, Ib/ft

      \i = absolute viscosity of water, centipoises

    (2)  Calculate Reynolds number corresponding to the minimum
fluidization velocity.
                                           x 10"3)
                        1   y(T.^8)(6o)(2.09 x
where
                                 5-100

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                                                           EM 1110-2-501
                                                             Part  1 of 3
                                                              29 Sep  78
             \  = Reynolds number
                                          2,  4
             p  = density of water,  Ib-sec /ft
              X»
                                                       2
             v  = minimum fluidization velocity,  gpm/ft


            d^  = 60 percent finer size of the sand,  mm, *0.75


    3.28 x 10   - conversion factor, mm to ft


              y = absolute viscosity, centipoises

                                       -3
           7.U8 = conversion factor, ft  to gal


             60 = conversion factor, sec to min


    2.09 x 10   = conversion factor, centipoises  to Ib-sec/ft


    (3) 'If  (R )  > 10 , apply a correction factor to the calculated

               n f
value of  v   as follows:




                          ** = I
where


    1C = correction factor


    (k)  Calculate the unhindered settling velocity as follows:
where

                                             2
    v  = unhindered settling velocity, gpm/ft
     s
                                              2
    v  = minimum fluidization velocity, gpm/ft


    (5)  Calculate Reynolds number based on the unhindered settling

velocity.
 \

n'
                              P.v dg (3.28 x icT3)
                               * s PU

                            y(7.U8)(60)(2.09 x 10~


                                 5-101

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EM 1110-2-501
Part 1 of 3
29 Sep 78
where
    (R \  = Reynolds number
      11 S                           2,  k
       p  = density of water, lb-sec /ft
                                                o
       v  = unhindered settling velocity, gpm/ft
        S
      d,-  = percent of sand SS0.075 mm
        y = absolute viscosity, centipoises
    (6)  Calculate expansion coefficient as follows.
                           n  =
where
    n  = expansion coefficient
    (T)  Using  v_  and  n  , calculate the constant  K   for the
system.
where
                                              2
    v_p = minimum fluidization velocity, gpm/ft
     £ = porosity of unexpanded media
    n  = expansion coefficient
    (8)  Calculate the desired porosity at the desired bed expansion.

                               ^   1- E
                                D"l- I
where
    D  = depth of expanded bed, ft

                                   5-102

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
    D = depth of unexpanded ted, ft

    e = porosity of unexpanded bed

    e = porosity of expanded "bed

    (9)  Calculate the backwash rate.

                                        n
                              BR = Ke(e) Q

where
                              2
    BR = backwash rate, gpm/ft

    K  = system constant

     e = porosity of expanded bed

    n  = expansion coefficient

    g.  Select wash water troughs arrangement and calculate depth of
wash water troughs.


                              Q = 2.U9bh3//2

where

     Q = total trough flow, cfs

     b = trough width, ft

    h  = trough minimum depth, ft

    h.  Select an underdrain system and calculate the minimum total
filter depth.

                      TD = UD + GD + MD + MOD + FB

where

     TD = total filter depth, ft

                                 5-103

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EM 1110-2-501

Part 1 of 3

29 Sep 78


     UD = depth of underdrain, ft


     GD = gravel depth, ft


     MD = media depth, ft


    MOD = maximum operating depth of water above sand, 3-5 ft


     FB = freeboard, ft


    i.  Calculate total head necessary to backwash water.




                       TH = HLUD + HLG + HLM + DWT




where


      TH = total head necessary for backwash


    HLUD = head loss in underdrain (manufacturer's requirement)


     HLG = head loss in gravel (c above)


     HLM - head loss through fluidized bed (d above)


     DWT - total depth from top of wash water trough to underdrain, ft


    ;j.  Assume backwash time and calculate total backwash water

needed.



                           BWW = (BR)(BWT)(SA)'
where
    BWW = total backwash water, gal

                               2
     BR = backwash rate, gpm/ft


    BWT = backwash time, min

                          2
     SA = surface area, ft
                                 5-

-------
5-72.  Output Data.
                                                           EM  1110-2-501

                                                            Part  1  of  3

                                                              29 Sep 78
a.


b.
c.
d.
e.
f.
g-
h.
i .
J.
k.
5-73.
Depth Diameter Shape
Layer ft ft Factor
1 XX. X XX. X XX. X
2 xx. x xx. x xx. x
3 xx. x xx. x xx. x
k XX. X XX. X XX. X
2
Average loading rate, gpm/ft .
2
Surface area, ft .
Under drain head loss, ft.
Wash water gutter width, ft.
Wash water gutter depth, ft.
Terminal head loss through bed, ft.
Maximum head for "back-washing, ft.
Total filter depth, ft.
Wash water needed, gal.
2
Backwash rate, gpm/ft .
Example Calculations.
Specific
Gravity
XX. X
XX. X
XX. X
XX. X











    a.  Select a loading rate and calculate filter surface area.
                             SA =
 Q   10
  avg

LR(2U)(60)
where
      SA = surface area, ft
    Q    = average flow, 1 mgd
                                 5-105

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EM 1110-2-501
Part 1 of 3
29 Sep 78
                                     2
      LR = loading rate, 6 gal/min/ft

      2h = hr/day

      60 = min/hr


                              CA - 1 x 106
                              bA ~ 6(2M60


                              SA = 116 ft2
    b.   Select filter medium and evaluate size distribution and depth of
 each layer.

 Anthracite

                     Depth = 18 in.

            Effective size = 1.2 mm

    Uniformity coefficient =1.5

 Sand

                     Depth = 12 in.

            Effective size = 0.5 mm

    Uniformity coefficient = l.U

    c.   Calculate terminal head loss through filter using Kozeny
 equation.
                h
                  f
d -
1
                                          p/  \3.28 x 10"
 vhere

              h   =  head loss in depth of bed, ft


                                   5-106

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                              29 Sep  78

              L = length,  1.5 ft anthracite,  1.0 ft sand

              K = coefficient of permeability,  6

                                                 — 5   2
              v = kinematic viscosity,  1.088  x  10   ft /sec
                                                         2
              g = gravitational acceleration, 32.2 ft/sec

              e = porosity, 0.50 anthracite,  0.^4-0 sand

              v = approach velocity,  O.OU fps

             a  = shape factor, 8.5
              s
             d  = mean particle size,  1.2 mm  anthracite, 0.5 mm sand
             _'}
    3.28 x 10   = conversion factor,  mm to ft

for anthracite
        5
1.088 x 10 5\
32.2 /
(1 - 0.5)2
L 0.53
                                          o.oU
                                           LI
                                          1.2
                                                            1
                                                        3.28 x 10
                 -3
       hf = 1.13 ft
for sand
      hf  = s  1.088 x 10 5
1.0
                   32.2
                        d - o.u;
                                    o.ok
°'5/  V3.28 xio-3
       hf = 5.^5 ft
 Total hf = 6.58 ft
    d.   Calculate the unit head loss through each expanded media.
                                 5-107

-------
EM 1110-2-501

Part 1 of 3

29 Sep 78
                      Ap = D(l - e)  (G    - G   \
                                     V s,m    s,w,/
where



      Ap = pressure drop across fluid!zed bed, ft



       D = unexpanded bed depth, 1.5 ft anthracite, 1.0  ft  sand



       e = porosity of unexpanded media, 0.50 anthracite, O.kO  sand



    G    = specific gravity media, 1.67 anthracite, 2.65  sand
     s 5 in.


    G    = specific gravity water, 1.0




              Ap anthracite = 1.5(1 - 0.5)  (1.67 - 1.0)




                         Ap = 0.50 ft




                    Ap sand = 1.0(1 - O.U)  (2.65 - 1.0)




                         Ap = 0.99 ft



    e.  Calculate total head loss through expanded media.




                          (Ap)T = EAp




                          (Ap)T = 0.50 + 0.99




                          (Ap)T = l.li9 ft




    f.  Calculate rate of filter backwashing.



    (l)  Calculate minimum fluidization velocity




                                1.82 r  /T,    „ N-,0.9U
0.00381(d,n)±lCV fw  (V  - W \~\
	60	L sy m    s/J
               Vf                   0.88
                                   y
                                   5-108

-------
                                                           EM 1110-2-501
                                                             Part 1 of  3
                                                               29 Sep 78
where

                                               2
     v  = minimum fluidization velocity, gpm/ft

    dx-n = 60 percent finer size of sand, 0.75 mm

     W  = specific weight of water, 62. U lb/ff
      s

     ¥  = specific weight of sand, 165 Ib/ft

      y = absolute viscosity of water, 1.009 centipoises
               0.00381(0.75)1'82  {62.'U[2.65(62.U) - 62.1i]l°-9U
             V™
           n                           f\ I

           f                      1.0090'1
          v  = 8.68 gpm/ft2 = 0.0193 fps
    (2)  Calculate Reynolds number corresponding to the minimum fluidiza-
tion velocity.
                             y(7. U8)60(2. 09 x 10"5)

where
(E \
                = Reynolds number
                                               2   h
             p  = density of water, 1.9^ Ib-sec /ft

                                                            2
             V- = minimum fluidization velocity, 8.68 gpm/ft


            cL-  = 60 percent finer size of sand, 0.75 mm


              y = absolute viscosity, 1.009 centipoises

             _0
    3.28 x 10   = conversion factor, mm to ft

                                       o
           7.^8 = conversion factor, ft  to gal
                                 5-109

-------
EM 1110-2-501

Part 1 of 3


29 Sep  78


             -5                                              ?
    2.09 x 10   = conversion factor, centipoises to lb-sec/ft



             60 = conversion factor, sec to min
                  (E\  = 1-9H(8.68)(0.75)(3.28 x


                  ^ n'f     1.009(7.^8)60(2.09 * ]
                  (R )  = it.u
                  V n/f






    (3)  Because  /R \  < 10 , no correction factor is needed.
                  \ 1+ -f


    (k)  Calculate the unhindered settling velocity as follows:
                               vs = 8.U5vf




where



                                             2
    v  = unhindered settling velocity, gpm/ft
     s



    v  = minimum fluidization velocity, 8.68 gpm/ft
                             v  = 8.1+5(8.68)
                              S




                             v  = 73.3 gpm/ft2
                              o





    (5)  Calculate Reynolds number based on the unhindered settling

velocity.




                        P.v d,n(3.28 x 10^)


              (H )  =    £ S 6°	=-= 8.U5(R )

              V n/                   9 x 10"5)       V n/f
where



                                                     2

       vs = unhindered settling velocity, 73.3 gpm/ft




      : \  = Reynolds number for minimum fluidization velocity, UJ
       / -p






                                 5-110

-------
                                                          EM 1110-2-501

                                                            Part 1 of 3


                                                              29 Sep 78
    (K \  = Reynolds  number for  unhindered  settling velocity
    v  n;
(Hn)
                                s



                                  . 37.2
    (6)  Calculate expansion coefficient.
where
       n  = expansion coefficient
        e
    /R \  = Reynolds number for unhindered settling velocity, 37-2


        S



                           n  = 1^5(37.2T0-1
                           n  = 3.1
                            e
    (7)  Calculate  K   for the system.
where

                                                     2

      v_p = minimum fluidization velocity, 8.68 gpm/ft



      K  = constant for system
       e


       e = porosity of unexpanded media, O.hd



      n  = expansion coefficient, 3.1
                                5-111

-------
 EM 1110-2-501
 Part 1 of 3
29 Sep 78
                           8.68 = K (0.40)3'1
                                =  1U9 gpm/ft2
     (8)  Calculate the desired porosity at the desired bed expansion.
where

    Dg = depth to expanded bed, 1.2 ft

     D = depth of unexpanded bed, 1.0 ft

     e = porosity of unexpanded bed, O.hO

     e = porosity of expanded bed

                            1.2 _ 1 - Q.hO
                            1-°*  i-r

                              r = 0.50

    (9)  Calculate the backwash rate.
                             BR = K (e) e
                                   e
where
                             p
    BR = backwash rate, gpm/ft
                            p
    K  = constant, 1^9 gpm/ft

     e = porosity of expanded bed, 0.50

    n  = expansion coefficient, 3.1
                                5-112

-------
                                                           EM 1110-2-501
                                                             Part  1 of 3
                                                               29  Sep 78

                            BR = lU9(0.50)3'1


                            BR = I'M gpm/ft

    g, h, i, and j.  Calculation of trough minimum depth (ho), total
filter depth (TD), total head for backwash (TH), and "backwash water
needed (BWW) are dependent upon the type of equipment selected for back-
washing the filter.

5-7l|.  Cost Data.  Appropriate cost data and economic evaluation may be
found in Chapter 8.

5-75.  Bibliography.

    a.  Amirtharajah, A. and Cleasby, J. L., "Predicting Expansion of
Filters During Backwash," Journal, American Water Works Association.
Vol 6H, 19T2, pp  52-59-

    b.  Burns and Roe,  Inc., "Process Design Manual for Suspended  Solids
Removal," prepared  for  the U. S. Environmental Protection Agency,  Tech-
nology Transfer,  Oct 1971, Washington, D.  C.

    c.   Camp, T.  R., "Theory of Water Filtration," Journal,  Sanitary  En-
gineering Division, American Society of  Civil Engineers, Vol 90, SAU,
196U, pp 1-30.

     d.   Cleasby,  J. L., "Deep  Granular Filters, Modeling and Simulation,"
Proceedings, Association of Environmental  Engineers  in  Profession,
Eighth Annual Workshop, 18-22  Dec  1972,  Nassau.

     e.   Cleasby,  J. L.  and  Baumann,  E. R., "Selection of Sand Filtration
Rates,"  Journal,  American Waterworks Association,  Vol 5^,  1962, pp
 579-602.

     f.   Gulp, R.  L. and Gulp,  G.  L., Advanced Wastewater Treatment, Van
 Nostrand,  New York, 1971.

     g.   Fair,  G.  M.,  Geyer,  J.  C., and Okun, D.  A.,  Water  Purification
 and Wastewater  Treatment and Disposal;  Water and Wastewater Engineer-
 ing,  Vol 2, Wiley, New York,  I960.
                                  5-113

-------
EM 1110-2-501
Part 1 of 3
 29 Sep  78

    h.  Hsuing, K. and Cleasby, J. L., "Prediction of Filter Perfor-
mance," Journal, Sanitary Engineering Division, American Society of
Civil Engineers, Vol 9^, SA6, 1968, pp 10*13-1070.

    i.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection,
Treatment, and Disposal, McGraw-Hill, New York, 1972.

    j.  O'Melia, C. R. and Stumm, ¥., "Theory of Water Filtration,"
Journal, American Water Works Association, Vol 59, Nov 1967  pp
1383-11*12.~~         ~                  '

    k.  Tchobanoglous, F. and Elliassen, R.,  "Filtration of Treated
Sewage Effluents," Journal, Sanitary Engineering Division, American
Society of Civil Engineers, Vol 96, SA2, 1970.

    1.  "Water Treatment Plant Design," prepared by American Society of
Civil Engineers, American Water Works Association, Conference of State
Sanitary Engineers, 1969.

    m.  Weber, W.  J., Jr., Physicochemical Processes for Water Quality
Control,  Wiley-Interscience,  New York,  1972.
                                5-llU

-------
                                                                               EM  1110-2-501
                                                                                 Part  1  of  3
                                                                                    29 Sep  78
           Table 5-12.   General  Features  of Construction and Operation of Conventional
                                   Slow and Rapid Sand Filters
         Feature
                                   Slow Sand Filters
                                                                        Did Sand Filters
Rate of filtration

Size of bed

Depth of bed



Size of sand
1 to 3 to 10 mgad

Large, half acre

12 in. of gravel; 1*2 in.  of sand,
  usually reduced to no less than
  21* in. by scraping

Effective size 0.25 to 0.3 to
  0.35 mm; coefficient of nonuni-
  formity 2 to 2.5 to 3
Grain size distribution    Unstratified
  of sand in filter
Underdrainage system
 Loss  of head

 Length of  run between
   cleanings

 Penetration of  suspended
   matter

 Method of  cleaning
 Amount of wash water used
   in cleaning sand

 Preparatory treatment of
   water

 Supplementary treatment
   of water

 Cost of construction,
   U. S.

 Cost of operation
 Depreciation cost
Split tile laterals laid in
  coarse stone and discharging
  into tile or concrete main
  drains
 0.2  ft  initial to k ft final

 20 to 30 to  60 days


 Superficial


 (1)  Scraping off surface  layer
   of sand  and washing and storing
   cleaned  sand for periodic re-
   sanding  of bed;  (2) washing
   surface  sand and  sand  in place
   by washer  traveling over sand
   bed

 0.2  to  0.6 percent  of water
   filtered

 Generally  none


 Chlorination


 Relatively high
 Relatively low where sand is
   cleaned in place

 Relatively low
100 to 125 to 300 mgad

Small, 1/100 to 1/10 acre

18 in. of gravel; 30 in.  of sand
  or less; not reduced by washing


O.U5 mm and higher; coefficient of
  nonuniformity 1.5 and lower, de-
  pending on underdrainage system

Stratified with smallest or light-
  est grains at top and coarsest
  or heaviest at bottom

(l) Perforated pipe laterals dis-
  charging into pipe mains; (2) po-
  rous plates above inlet box;
   (3) porous blocks with included
  channels

1 ft  initial to  8  or  9 ft  final

12 to 2U  hr
 Deep


 Dislodging and  removing  suspended
   matter  by upward  flow  or back-
   washing,  which  fluidizes the bed.
   Possible use  of water  or air
   Jets,  or mechanical  rakes  to im-
   prove  scour
 1 to 1* to 6 percent of water
   filtered

 Coagulation, flocculation,  and
   sedimentat ion

 Chlorination
 Relatively low
 Relatively high
                                                               Relatively high
                                                                          From Fair, Geyer, and Okun, 1968
                                              5-115

-------
EM 1110-2-501
Part 1 of  3
  29  Sep 78
           Table  5-13.   Rules of Thumb for Underdrainage  System
1.  Ratio of area of orifice to
      area of bed served

2.  Ratio of area of lateral to
      area of orifices  served

3.  Ratio of area of main to
      area of laterals  served

U.  Diameter of orifices

5.  Spacing of orifices

6.  Spacing of laterals
[(1.5 to 5)  x  10  3]  to 1


(2 to h) to  1


(1.5 to 3) to  1


lA to 3A in.

3 to 12 in. on centers

Closely approximating
  spacing of orifices
                                                   From Fair, Geyer, and Okun, 1968
             Table 5-l4.  Design  Considerations for Various
                       Velocities and Flov Volumes
Piping
Influent
Effluent
Wash water supply
Wash vater drain
Filter to vaste
Velocity
fps
1 to U
3 to 6
5 to 10
3 to 8
6 to 12
Maximum Flow per
Filter Area Served
gpm/ft2
3 to 8
3 to 8
15 to 25
15 to 25
1 to 6
                                           From American  Water Works Association, 1969
                                 5-116

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                                                                  EM 1110-2-501
                                                                    Part 1 of 3
                                                                       29 Sep 78
          Table 5-15.  Typical Gravel Bed for Pipe Underdrain System
No. of Layers
Description
Depth of layer, in.
Square mesh screen opening, in.
Passing
Retained
1
1
1
3A
2
3
3A
1/2
3
3
1/2
1/U
k
k
iA
1/8
5
U
1/8
1/16
NOTE:  Bottom layer should extend to a point U in. above the highest  outlet  of
      wash water.                                            From Cuip and Culp, 1971
    Table 5-l6.  Typical Design Data for Dual-Media and Multimedia Filters

Characteristic

Anthracite
Depth, in.
Effective size, mm
Uniformity coefficient
Sand
Depth, in.
Effective size, mm
Uniformity coefficient
2
Filtration rate, gpm/ft

Anthracite
Depth, in.
Effective size, mm
Uniformity coefficient
Sand
Depth, in.
Effective size, mm
Uniformity coefficient
8.
Garnet
Depth, in.
Effective size, mm
Uniformity coefficient
2
Filtration rate, gpm/ft
Value
Range
Dual-Media

8 to 2U
0.8 to 2.0
l.U to 1.8

10 to 2k
0.3 to 0.8
1.2 to 1.6
2 to 10
Multimedia

8 to 20
1.0 to 2.0
l.U to 1.8

8 to 16
O.U to 0.8
1.2 to 1.6

2 to U
0.2 to 0.6

2 to 12

Typical


18.0
1.2
1.5

12.0
0.5
l.U
6.0


15.0
l.U
1.5

12.0
0.6
l.U

3.0
0.3
1.0
6.0
   Garnet becomes  intermixed with sand and anthracite.
                                                             From Met calf and Eddy, 1972
                                    5-117

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EM 1110-2-501
Part 1 of  3
29 Sep 78
       Table  5-17-   Typical Removals  by Tahoe Mixed-Media Filters

Substance
Phosphorus, total
Pho sphorus , di s s olved
Phosphorus, particulate
COD
BOD
SS
Turbidity, JU
Typical

Influent
0.65
0.1*5
0.20
23.00
9.00
15-00
7.00
Concentrations
mg/£
Effluent
0.05
0.05
0.00
15.00
5.00
0.00
0.30

Range
% R emo val
70 to 95
65 to 90
100
20 to 1*5 '
1*0 to 70
100
60 to 95
                                                         From Gulp and Culp, 1971
              Table 5-18.  Flows  and Velocities Determining
                          Filter  Piping Design

Piping
Influent
Effluent
Wash water supply
Backwash waste
Filter to waste

Velocity
fps
1 to H
3 to 6
5 to 10
3 to 8
6 to 12
Maximum Flow per
Filter Area Served
gpm/ft2
8 to 12
8 to 12
15 to 25
15 to 25
It to 8
                                                        From Culp and Culp, 1971
                                  5-118

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                                                          EM 1110-2-501
                                                            Part 1 of 3
                                                              29 Sep 78
                     Section XI.   VACUUM FILTRATION
5-76.  Background.

    a.  Vacuum filtration is one of the most  widely used methods  for
mechanical dewatering of wastewater sludges.   The process is  carried out
using a slowly rotating drum, the outside of  which is covered "by  a fil-
ter medium.  A portion (about 20-HO percent)  of the drum is submerged
in sludge in the vat below the drum.  Vacuum  (10-26 in.  of mercury)
is applied to the submerged portion of the trough.  As a result,  water
is drawn into the drum and a thin mat of sludge is formed on the  filter
medium.  As the filter rotates, the vacuum is continued, and further
moisture reduction occurs.  In addition, the  deposited cake is further
dried by air which rushes through the cake into the drum.  Before the
filter cake reaches the sludge vat again, it  passes over a roller and is
broken off onto a conveyor for ultimate disposal.  The time the drum
spends submerged in the slurry is called the  "filter time"; the time the
cake  spends on the drum above the vat is called the "drying time.

    b.  Vacuum filtration facilities are generally sold as a package
by various filter manufacturers.  In addition to the filter itself, the
package normally includes vacuum pumps, sludge feed pumps, filtrate
pumps, sludge conditioning tanks, chemical feed pumps, and belt con-
veyors that transport  dewatered filter  cake.   Filter medium made of
cloth (cotton, wool, nylon,  dacron, or  other synthetic material),  coil
springs,  or a wire-mesh  stainless  steel fabric are available in various
weaves of different porosities.

     c.  Vacuum filter  performance  is measured by  filtration rate and
dryness of the filter  cake.   Several factors affecting  the performance
of  a vacuum filter  include:

     (l)   Vacuum  —  As  the vacuum  increases,  the  filtration rate  and
the dryness of the  cake  also increase;  this  process  is  limited,  ob-
viously,  by capacity  of  the  drum.   An  ideal  filter  design would  incor-
porate two independent vacuum systems:   one  operating while the  cake  is
being formed,  and the  other  after  it comes out  of submergence  and  is
being dried.   A  vacuum of at least  20  in. of mercury is desirable.

     (2) .  Feed Solid Concentration  — In general,  the sludge  filtra-
tion rates increase directly in proportion to  the increase  in feed
 sludge solids concentration; a smaller filtrate volume  has  to be removed
 per pound of  filter cake formed.   The  practical limit  for  optimum opera-
tion for  sewage sludges  is  U-8 percent.


                                  5-119

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EM 1110-2-501
Part 1 of 3
29 Sep 78

     (3)  Drum Speed and Submergence — The drum speed influences the
 cycle time and consequently influences filter yield and filter cake
 moisture.  A decrease in filter cycle time should increase the yield.
 However, lower filter cake moisture will be obtained by increasing the
 filter cycle, thereby extending the drying cycle.   A submergence level
 of 20-40 percent has been used.   It is usually more economical to
 run the filter at lower submergence since it will increase the ratio of
 dewatering time to cake formation time, and will still allow a short
 cycle for greater filtration rates.

     (10  Chemical Conditioning of Sludge — Chemical conditioning of
 sludge is usually a necessary step prior to sludge vacuum filtration.
 Chemical conditioning agglomerates solids and causes a release of water,
 thereby making the sludge easier to filter.   A wide variety of chemicals
 have been evaluated for conditioning sludges prior to vacuum filtration.
 In general,  lime and ferric chloride are the most  commonly used condi-
 tioners.   Recently, some organic polyelectrolytes  have become popular  as
 sludge conditioners.   The amount and type of conditioning chemicals  re-
 quired depend on the physical and chemical characteristics of the sludge.
 Tables 5-19  and 5-20 summarize chemical doses reported from the operat-
 ing records  of various treatment facilities  (para  5-83b).

     d.   Vacuum filter systems are designed from data describing quanti-
 ties of sludge to be filtered,  sludge characteristics,  filtration rates
 cake moisture,  and filter operation cycles.   The data could  be  generated
 from laboratory or pilot  investigations  of the  sludge.  The  Buchner  fun-
 nel  test  and the filter  leaf  test are commonly  used  in  laboratory  test-
 ing  programs  for estimating the  filterability of sludges.  The  Buchner
 funnel  test  evaluates the optimum chemical requirements and  sludge
 filtration characteristics  measured in terms  of specific resistance.
 The  filter leaf test  determines  the effect of different fabrics,  fabric
 forms,  and drying times on  filter yield.   Table  5-21  summarizes  specific
 resistance; Table 5-22 presents  filter yields recommended  for various
 sewage  sludges.

     e.  Filter  yield,  or  production rate,  is  the basic factor used in
determining the  size  of vacuum filter installations.  A conservative de-
sign rate of  3-5  Ib/ft2/hr  has been widely used.  However, assuming the
yield to be equal to  the  solids  concentration of the  sludge to be fil-
tered is more accurate.  Generally, the yield may vary from 2 to 10
lb/ft^/hr.  The low values represent  filtration of fresh and digested
activated sludge;  the high values are typical for raw primary or primary
plus trickling  filter humus sludge filtration.
                                5-120

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                                                           EM 1110-2-501
                                                             Part 1 of, 3
                                                              29 Sep  78

    f.  The bibliography (para 5-83) contains thorough discussions of
the theory and application of vacuum filtration and example problems.

    g.  Vacuum filtration is being widely used for devatering sewage
sludges in small treatment facilities because of its flexibility, small
space requirement, and the excellent characteristics of the cake.  Thus,
vacuum filtration is a viable alternative for sludge dewatering in treat-
ment facilities serving recreation areas.

5-77.  Input Data.

    a.  Volume of sludge to be dewatered, gpd.

    b.  Initial moisture content of sludge, percent.

5-78.  Design Parameters.

    a.  Final moisture content of sludge, percent.
                                O
    b.  Specific resistance, sec /g (Buchner funnel test).

    c.  Applied vacuum, psi.

    d.  Fraction of cycle time for cake  formation  (formation time/cycle
time), depends on degree of  submergence.

    e.  Cycle time, min  (usually 1.5 to  5 min).

    f.  Filtrate viscosity,  centipoises.

    g.  Chemical dose, percent of dry weight  in solids fed to
filter.

    h.  Operation per week,  days.

    i.  Operation per day, hr.
                           o
    j.  Loading rate, Ib/ft  /hr.

    k.  Number of units.

 5-79.  Design Procedure.

     a.  Calculate filter loading rate.


                                  5-121

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 EM 1110-2-501
 Part  1  of  3
 29 Sep  78
                           M'35-7

                            R = r(lO~7) = sec2/g
                         C =
                                C.         Cf
                             100 - C±   100 - C

where

    LR = filter loading rate, Ib/ft2/hr

     X = form time/cycle time (0.1 to 0.6)

     C = weight of dry solids in cake, g/m£

     P = applied vacuum, psi (5 to 15 psi)

     V = filtrate viscosity, centipoises

     r = specific resistance (Buchner funnel test or Table 5-21),
         secVg

     t = cycle time (1.5 to 5 min), time of revolution of drum

    C. = initial moisture content of sludge, percent

    C~ = final moisture content of sludge, percent

    b.  If data are not available, select loading rate from Table 5-22
or use 3.5 Ib/ft2/hr.

    c.  Calculate required total filter area.


                            V(100 - C.)(8.3U)(7)2U
                      TFA =
                              LR(100)(HPD)(DP¥)

where

    TFA = total filter area, ft2


                                  5-122

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                                                          EM 1110-2-501

                                                            Part 1 of 3

                                                                29 Sep 78
      V = sludge volume,  gal/day


     C.  = initial moisture content  of sludge,  percent



     LR = filter loading  rate,  Ib/ft /hr



    HPD = operation per day,  hr



    DPW = days/week


    d.  Calculate amount  of chemicals required.



                           C,V                 (100 -  C )
                   _        Cl        /rrWO ->1, \	i_
                CK —
                     (HPD) (DPW) (100) """'^'    100


where


     CR = amount of chemicals required, Ib/hr


     C  = chemical dosage, percent of dry weight of solids fed to

          filter


      V = sludge volume, gal/day


    HPD = operation per day, hr


    DPW = days/week


     C  = initial moisture content of sludge, percent
      i

    e.  Select number of filters and calculate area per filter.
                                       NF


where

                             2
    APF = area per  filter,  ft

                               2
    TFA = total  filter  area, ft


     NF = number of filters





                                  5-123

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 EM 1110-2-501
 Part 1 of 3
  29 Sep 78

 5-80.  Output Data.

     a.  Loading rate, Ib/ft2/hr.

     b.  Total filter area, ft2.

     c.  Chemical requirements,  Ib/hr.

     d.  Initial moisture content,  percent.

     e.  Final moisture content, percent.

     f.  Cycle time, min.

     g.  Formation time,  min.

     h.  Chemical dose,  percent.

     i.  Applied vacuum,  psi.

     j.   Operation per day, hr.

     k.   Operation per week, days.

 5-8l.   Example  Calculations.

     a.   Calculate filter loading rate.
                           LE -
                            R = r(lO T) = sec2/gm
                         C =

                             100 - C±   100 - C
where
    LR = filter loading rate, Ib/ft2/hr

     X = form time/cycle time, 0.5


                                 5-12*1

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                                                      EM 1110-2-501
                                                        Part 1 of 3

                                                           29 Sep  78

 C = weight of dry solids in cake,  g/m£

 P = applied vacuum,  10 psi

 y = filtrate viscosity, 1.12 centipoises

 R = specific resistance

 t = cycle time, 3 min

                                  7    2
 r = specific resistance, 3.0 x 10  sec  /g

C  = initial moisture content, 97-5 percent
 i

C  = final moisture content, 75.0 percent
                      R = 3.0 x 10T (10 T)
                                 2
                      R = 3.0 sec /g
                   C =
                          97.5    _    75.0
                       100 - 97.5   100 - 75.0
                   C = 0.028 g/m£



                  LR _ o.    o.5(0.028)lQ1/2
                  LR -
                  LR = U.2 rb/ft2/hr
b.  Use  LR = U.2 Ib/ft2/hr.
c.  Calculate required total filter area.


                          V(lOO - C.
                    nrp/\ _
                             - ._ _________ , . . -------
                             LR(IOO)HPD(DPW)
                             5-125

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 EM 1110-2-501
 Part J of 3

29 Sep 78
 where

     TFA =. total filter area, ft2

       V = sludge volume, 7000 gpd

      C^ = initial moisture content, 97.5 percent

      LR = loading rate, lj.2 It>/ft2/hr

     HPD = hours of operation per day, 16

     DPW = days of operation per week, 5

       7 = days/week

      2k = hr/day


                      TFA  =  -7000(100 - 97.5)8.3Um2_U_
                                  4.2(100)16(5)


                      TFA  =  730  ft2


    d.  Calculate amount  of chemicals  required.

                             cdV24            100 -  C.
                      CR = HPD(DPW)100  7(8'3^

where

     CR = chemical requirement,  Ib/hr

     Cd = chemical dosage, 1 percent

      V = sludge volume, 7000 gpd

    HPD = hours of operation per day, 16

    DPW = days of operation  per  week, 5

     C±  = initial moisture,  content, 97.5 percent


                                 5-126

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                                                          EM 1110-2-501
                                                            Part 1 of ^
                                                              29 Sep 78
                        1(7000)(7)  8 ^  100 - 97.5
                         16(5)100  °'^     100
                   CR = 1.28 Ib/hr

    e.  Select number of filters and calculate area per filter.
                               APF =
                                      NF
vhere
                             2
    APF = area per filter, ft

    TFA = total filter area, 730 ft2

     NF = number of filters, 2
                              APF = 365 ft2
5-82.  Cost Data.  Appropriate cost data and economic evaluation may be
found in Chapter 8.

5-83.  Bibliography.

    a.  American Society of Civil Engineers and the Water Pollution Con-
trol Federation, "Sewage Treatment Plant Design," Manual of Practice
No. 8, 1959, 1961, 1967, 1968, Water Pollution Control Federation,
Washington, D. C.

    b.  Burd, R. S., "A Study of Sludge Handling and Disposal," Publica-
tion WP-20-H, May 1968, Federal Water Pollution Control Administration,
Washington, D. C.

    c.  Eckenfelder, W. W., Jr., Water Quality Engineering for Practicing
Engineers, Barnes and Nobel, New York, 1970.
                                 5-127

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EM 1110-2-501
Part 1 of 3
29 Sep 78

    d.  Eckenf elder, W. W. , Jr., and Ford, D. L., Water Pollution Con-
trol, Pemberton Press, New York, 1970.

    e.  Jones, B. R. S., "Vacuum Sludge Filtration, II, Prediction of
Filter Performance," Sewage and Industrial Wastes, Vol 28, No.  9, Sep
1956, pp 1103-1115-

    f.  Malina, J. F. , "Sludge Filtration and Sludge Conditioning,"
Advances in Water Quality Improvements, University of Texas, Water Re-
sources Symposium No. 3, 1970, Austin, Tex.

    g.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection.
Treatment, and Disposal, McGraw-Hill, New York,  1972.

    h.  Roy F. Weston, Inc., "Process Design Manual for Upgrading Exist-
ing Wastewater Treatment Plants," prepared for the U. S.  Environmental
Protection Agency, Technology Transfer, Oct 1971, Washington, D.  C.

    i.  Simpson, G. D. , "Operation of Vacuum Filters," Journal,  Water
Pollution Control Federation, Vol 36, Dec 196^,  pp
    j.  U. S.  Environmental Protection Agency,  Technology Transfer
Seminars, "Sludge Handling and Disposal," 11-12 Dec  1973, Washington,
D. C.
                                 5-128

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                                                            EM 1110-2-501
                                                              Part 1 of 3
                                                                29 Sep 78
        Table 5-19-  Average  Chemical  Doses for Vacuum Filtration
Chemical Dose
Rate, percent
Type of Sludge
Raw primary
Digested primary
Elutriated digested
primary
Raw primary plus filter
humus
Raw primary plus
activated
Raw activated
Digested primary plus
filter humus
Digested primary plus
activated
Elutriated digested pri-
mary plus activated:
Average without lime
Average with lime
Ferric
Chloride
2.1
3.8
3.U
2.6
2.6
7.5
5.3
5.6
8.U
2.5
Lime
8.8
12.1
0.0
11.0
10.1
0.0
15.0
18.6
0.0
6.2
Yield
Ib/fWhr
6.9
7.2
7.5
7.1
U.5
0.0
U.6
U.o
3.8
3.8
Cake
Moisture
percent
69.0
73.0
69.0
75.0
77.5
8U.O
77.5
78.5
79-0
T6.2
          Table 5-20.  Polyelectrolyte Doses (Usual Ranges)
                            Vacuum Filtration
                             From Burd, 1968

                            for
Type of Sludge
Raw primary or raw primary
plus filter humus
Digested primary
Dose Rate
percent
0.2 to 1.2
0.2 to 1.5
Yield
Ib/ft2/hr
6 to 20
h to 15
Cake
Moisture
percent
63 to 72
66 to 7^
Digested primary plus
  activated
0.5 to 2.0
to 8
68 to 76
                                                              From Burd, 1968
                                 5-129

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EM 1110-2-501
Part  1 of  3
29 Sep  /t>
             Table 5-21.  Specific Resistance of Some Industrial
                            and Municipal Sludges
             Type of Sludge
  Neutralization of sulfuric acid with
    lime slurry
  Neutralization of sulfuric acid with
  Specific
 Resistance
sec2/g x ioT
at 500 g/cm^
   1 to 2
Coefficient of
Compressibility
dolomitic lime slurry
Processing of aluminum
Paper industry
Neutralization of fatty acids with
sodium carbonate
Froth flotation of coal
Malt whisky distillery
Mixed chrome and vegetable tannery
Biological treatment of chemical
wastes
Activated (domestic)
Raw conditioned (domestic)
Digested conditioned (domestic)
Digested and activated (conditioned)
Raw (domestic)
3
3
6
T
80
200
300
300
2880
3.1
10.5
lU.6
UTO
0.77
O.UU
0.0
0.0
1.6
1.3
0.0
0.0
0.81
1.00
0.0
1.10
0.5^
                                                                  From Eckenfelder, 1970
             Table 5-22.  Expected Performance of Vacuum Filters
                    Handling Properly Conditioned Sludge
                 Type of Sludge
  Fresh solids
    Primary
    Primary plus trickling filter
    Primary plus activated
    Activated (alone)

  Digested solids  (with 01 without elutriation)
    Primary
    Primary plus trickling filter
    Primary plus activated
                   Yield, Ib/ft2/hr

                        h to 12
                        U to 8
                        U to 5
                      2.5 to 3.5

                        U to 8
                        U to 5
                        U to 5
                                                                    From Simpson, 1964
                                       5-130

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                                                           EM 1110-2-501
                                                             Part  1  of  3
                                                              29 Sep 78

                      Section XII.   CENTRIFUGATION

5-81*.   Background.

    a.  Centrifugation is a widely used process for concentrating  and
dewatering sludge for final disposal.   The process offers  the following
advantages (para 5-91c ) '•

    (l)  Capital cost is  low in comparison with other mechanical
equipment.

    (2)  Operating costs  are moderate,  provided flocculants are not
required.

    (3)  The unit is totally inclosed,  thus odors are minimized.

    (U)  The unit is simple and will fit in a small place.

    (5)  Chemical conditioning of the sludge is often not  required.

    (6)  The unit is flexible and can process a wide variety of solids.

    (T)  Minimum supervision is required.

    "b.  Disadvantages associated with centrifugation are:

    (l)  Without the use of chemicals,  solids capture is often poor.

    (2)  Chemical costs can be substantial.

    (3)  Trash must often be removed from the centrifuge feed by
screening.

    (U)  The percentage of cake solids is often lower than that result-
ing from vacuum filtration.

    (5)  Maintenance costs are higher than vacuum filtration.

    (6)  Fine solids (in concentrate) that escape the centrifuge may
resist settling when recycled to the head of the treatment plant and
gradually build up in concentration, eventually raising effluent solids
level.

    c.  Centrifuges applicable to sludge thickening and dewatering


                                 5-131

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EM 1110-2-501
Part 1 of 3
29 Set 78
fall into three general classifications:   disc, basket,  and the currently
popular solid-bowl.  Basically, centrifuges separate solids from liquids
through sedimentation and centrifugal force.   Process variables in cen-
trifugation include feed rates, sludge solids characteristics, feed
consistency, and chemical additives.   Machine variables  include bowl de-
sign, bowl speed, pool volume, and conveyor speed.

    d.  The main objectives in centrifuge design are cake dryness and
solids recovery.  The effect of the various parameters on these two
factors are summarized in Table 5-23.  Operating data reported in the
literature indicate that raw primary and digested primary sludges de-
water easily.  With polymer addition, a centrifuge (fig. 5-13) can pro-
duce 25-^0 percent cake solids with better than 90 percent recovery.
                                                    SLURRY IN
           LIQUIDS
           DISCHARGE
SOLIDS
DISCHARGE
                 Figure 5-13.   Schematic of a centrifuge.

Waste activated sludge, however, is difficult to thicken or dewater
with centrifugation.  High polymer dosages will be required to produce
8-10 percent cake solids and 90 percent recovery.

    e.  Design criteria for centrifugation systems are scarce.  One
criterion used in determining the size of centrifuge required is the
power requirement per gallon per minute of inflow (0.5-2.0 hp per gpm) .
Generally, a power requirement of 1.0 hp/gpm of inflow is applicable to
most centrifuges commercially manufactured.
                                 5-132

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                29 Sep 78
5-85.  Input Data.

    a.  Sludge flow, gpd.

    b.  Sludge concentration, percent solids.

5-86.  Design Parameters.

    a.  Centrifuges power requirement, hp/gpm (^.0).

    b.  Operation per day, hr.

    c.  Operation per week, days.

    d.  Number of units.

    e.  Excess capacity factor, 1.25.

    f.  Chemical dosage, percent of dry weight of solids.

5-87•  Design Procedure.

    a.  Calculate total power required.


                      = (SF)(CPR)(7 DPW)(ECF)(2U HFD)
                         (2k HPD x 60 MPH)(DPW)(HPD)

where

    THP = total power required, hp

     SF = sludge flow, gpd

    CPR = centrifuge power requirement,  hp/gpm

    DPW = operation per week, days

    ECF = excess capacity factor, 1.25

    HPD = operation per day, hr

    HPH = minutes per hour
                                 5-133

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EM 1110-2-501
Part 1 of 3
 29  Sep 78
    b.  Calculate power per unit.  Use duplicate units
                              ,   /  .,    THP
                              hp/unit = ^j-


where

    THP = total power required, hp

     NU = number of units


    c.  Compare horsepower with manufacturer's specification and
select centrifuge that meets the requirements.

    d.  Calculate chemical requirements.


                   (SF)(T DPW)(Cj(8.3H Ib/gal) /100 - C.
                                                        j
                   _ _
                         (HPD)(DPW)(100)        \  100

where

     CR = chemical requirements, Ib/hr

     SF = sludge flow, gpd

     C  = chemical dosage,  percent of dry weight of solids fed to
          filter

    HPD = operation per day, hr

    DPW = operation per week, days

     C. = initial moisture  content of sludge,  percent

5-88.  Output Data.

    a.  Power required/unit.

    b.  Number of units.

    c.  Chemical requirements,  Ib/hr.

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                29 Sep 78
    d.  Sludge flow, gal/day.

    e.  Initial solid concentrate, percent.

    f.  Operation per day, hr.

    g.  Operation per week, days.

 5-89.  Example Calculations.

    a.  Calculate total power required.


                          Twp _ SF(CPR)7(ECF)2U
                          i±ir ~  2M60)DPW(HPD)

where


    THP = total power required, hp

     SF = sludge flow, TOGO gpd

    CPR = centrifuge power requirement, 1.0 hp/gpm

    ECF = excess capacity factor, 1.25

    DPW = days of operation per week, 5

    HPD = hours of operation per day, 16
                            - 7000(7)2Ml.25)1.0
                            ~    2U(60)5(16)
                        THP = 12.8hp


    b.  Calculate power per unit.


                              hp/unit = ^


where


    hp/unit = power per unit, hp



                                 5-135

-------
EM 1110-2-501
Part 1 of 3

 29 Sep 70

    THP = total power required, 12.8 hp

     NU = number of units, 2


                             ,  /  ..    12.8
                             hp/unit = ——



                             hp/unit = 6.U hp


    c.  Compare horsepower with manufacturer's specification and select
centrifuge that meets the requirements.

    d..  Calculate chemical requirements.


                           SF(7)(C,)8.3U AGO - C.
                      CR =
                            HPD(DPW)100  V   100

where

     CR = chemical requirements, lb/hr

     SF = sludge flow, TOOO gpd

     C  = chemical dose, 1 percent

    HPD = hours of operation per day, l6

    DPW = days of operation per week, 5

     C. = initial moisture content of sludge,  97.5 percent
                    PR = TOOO(T)(1)8.3U /loo - 97.5\
                            16(5)100V   100    /
                    CR =1.28 Ib/hr

5-90.  Cost Data.  Appropriate cost data and economic evaluation may be
found in Chapter 8.
                                 5-136

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3

                                                              29  Sep  78
5-91.   Bibliography»

    a.  Albertson, 0. E.  and Guidi, E.  E.,  Jr.,  "Centrifugation  of Waste
Sludges," Journal, Water Pollution Control  Federation,  Vol Ul, Apr 1969,
pp 607-628.

    b.  Bernard, J.,  "Sludge Centrifugation," 1st Seminar on Process
Design for Water Quality Control, 1970, Vandertdlt University, Nashville,
Tenn.

    c.  Burd, R. S.,  "A Study of Sludge Handling and Disposal,"  Publi-
cation WP-20-^, May 1968, Federal Water Pollution Control Administration,
Washington, D. C.

    d.  Jenks, J. H., "Continuous Centrifuge Used to Dewater Variety of
Sludges," Waste Engineering, Jul 1958,  pp 360-361.

    e.  Roy F. Weston, Inc., "Process Design Manual for Upgrading Exist-
ing Waste-water Treatment Plants," prepared for the U.  S. Environmental
Protection Agency, Technology Transfer, Oct 1971, Washington, D. C.

    f.  U. S. Environmental Protection Agency, Technology Transfer
Seminars, "Sludge Handling and Disposal," 11-12 Dec 1973, Washington,
D. C.

    g.  White, W. F.  and Burns, T. E.,  "Contiguous Centrifugal Treatment
of Sewage Sludge," Water and Sewage Works,  Vol 109, Oct 1962, pp
38U-386.
                                 5-137

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EM 1110-2-501
Part 1 of 3

29 Sep 78
              Table 5-23.  Summary of the Effect of Various
                  Parameters on Centrifuge Performance
 To Increase Cake Dryness

Increase "bowl speed

Decrease pool volume

Decrease conveyor speed

Increase feed rate

Decrease feed consistency

Increase temperature

Do not use flocculants
To Increase Solids Recovery

Increase bowl speed

Increase pool volume

Decrease conveyor speed

Decrease feed rate

Increase temperature

Use flocculants

Increase feed consistency
                                                             From Burd, 1968
                                  5-138

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                                                           EM 1110-2-501
                                                             Part 1 of 1
                                                               29 Sep 78

                      Section XIII.   MICROSCREENING

5-92.  Background.

    a.  Microscreening is a method of filtration which uses fabric as
the filtering medium.   Microscreens  usually consist of a special metal-
lic fabric mounted on the periphery of a revolving drum.  The untreated
water flows into the drum and radiates outward through the microfabric,
leaving behind the suspended solids  removed by the cloth.   The solids
retained on the inside of the rotating screen are carried upward to a
row of backwash jets which flush them into a hopper, which is mounted on
a hollow axle of the drum, for return to the treatment plant.

    b.  Microscreens have been used as a tertiary treatment process for
filtering effluents from biological waste treatment systems.   In a study
at Lebanon, Ohio (para 5-99a), suspended solids removals of 89 and
73 percent were obtained with 23- and 35-micron fabrics, respectively.
Backwash water averaged 5 percent of the throughput volume.  Studies at
Chicago Sanitary District (para 5-99J) reported an effluent suspended
solids of 6-8 mg/H and a BOD of 3-5-5 mg/£ when applying a good Duality
(suspended solids = 20-25 mg/£ and BOD 15-20 mg/Jl) activated sludge ef-
fluent to a 23-micron screen.  Microscreens were reported to be ineffec-
tive in the filtration of alum floes. Removal efficiencies as recommended
for secondary effluents are presented in Table 5-2^ (para 5-99d).

    c.  Operating problems that have been reported for microscreens in-
clude slime growths, grease accumulation, and the possible buildup of
iron and manganese on the screen.  Ultraviolet lights placed in prox-
imity to the screen have been somewhat successful in controlling slime
growths.  In general, however, units must be taken out of service on a
regular basis for screen cleaning.  Chlorine solutions, acid solutions,
and hot water have been used as cleaners.

    d.  Currently, there is little information available on the design
of microscreening devices.  Individual manufacturers have specific de-
signs and sizes for various types of installations, and much of this
design information is proprietary in nature.  Design elements required
for microscreening include hydraulic loading, solids inputs, solids
character, microscreen fabric, backwash, and head loss.

    e.  The rate of flow through the screen is limited by the allowable
head loss and the character and concentration of the suspended solids
in the feed'.  Typical loading rates of 2.5-10 gpm/ft2 of submerged drum
surface area have been reported.  Studies at Chicago reported an upper


                                5-139

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EM 1110-2-501
Part 1 of 3
 29  Sep  78

limit on hydraulic loading of 6.5 gpm/ft2.  The solid loading was the
limiting design factor with an upper limit of 0.88 Ib/ft2/day.  Head
loss across the microscreening unit, including inlet and outlet struc-
tures, is limited to 12-18 in. for normal flows and to 6 in. for peak
flows.

    f.  The continuous backwashing jets require 3-5 percent of the total
throughput volume.  In a recent study (para 5-991) the cleaning effi-
ciency depended on the fabric nominal size, screen speed, and backwash
pressure.  Cleaning efficiency was found to increase with increasing
fabric nominal pore size to a maximum level of 0.90-0.95 at a pore size
of 16.5 microns and then to decrease slightly with increasing fabric
pore size.   Screen speeds of 1*1.0-25.8 ft2/min were found to provide a
cleaning efficiency of 0.85.  Cleaning efficiency was independent of
pressure in the range of 15-35 psig and of speed in the range of
14.0-25.8 ft2/min.  The authors concluded that at no time should a
microscreen unit be specified for specific application in the absence
of pilot scale microscreen performance data developed with the water
under consideration.   Tables 5-25 and 5-26 summarize the microscreen
sizes available from two manufacturers.    A schematic of a microstrainer
appears in Figure 5-14.
                                       From Metcalf and Eddy, 1972

               Figure 5-14.   Schematic of a microstrainer.
                                 5-140

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                29 Sep  78

5-93.  Input Data.

    a.  Wastewater flow.

    (l)  Average flow, mgd.

    (2)  Peak flow, mgd.

    b.  Suspended solids concentration, mg/£.

    c.  Effluent requirements, mg/£.

5-9^-  Design Parameters.

    a.  Head loss across microscreen, in. , ss6 in. water.

    b.  Initial resistance of clean filter fabric, in feet, at a given
temperature and standard flow conditions (manufacturer's requirements).

    c.  Filterability index of influent measured on fabric in use
(volume of water obtained per unit head loss when passed at a standard
rate through a unit area of standard filter).  (From laboratory.)

    d.  Speed of strainer (number of square feet of effective fabric
entering water in given time), ft2/min (lit. 0-25. 8 ft2/min).

    e.  Constants:  m = 0.0267;  n = 0.1337

5-95-  Design Procedure.  Utilize the Boucher concept of filter-
ability index (para 5~99b).

    a.  Calculate the effective submerged area of the screen.


                                                106
                                 H(2it)60

where
                                     2
     A - effective submerged area, ft

-------
 EM 1110-2-501
 Part 1 of 3

  29  Sep  78


      m = 0.0267


      Q = total rate  of  flow through unit, mgd.


     Cf = initial resistance of  clean filter fabric, feet, at a given
          temperature and  standard flow conditions  (manufacturer's
          requirements)  (1.8 ft  for 23-micron screen; 1.0 ft for
          35-micron screen)


      n = 0.1337


      I = filterability  index of influent measured on fabric in use
          (laboratory) «0.5(SS)
                              eff
                              Q
      S = speed of strainer, ft  /min


      H = head loss across microscreen, in. , ss6 in.


    b.   Calculate hydraulic rate of application.



                            HP =  (Q)do6)
                                 (A)(2lO(60)

where

                               r>
    HR = hydraulic rate, gpm/ft


      Q = total rate of flow through unit, mgd

                                     t~)
     A = effective submerged area,  ft


    c.   Calculate solids rate of application.


                                (Q)(C.)(8.3U)
where


    SR = solids loading rate, Ib/ft2/day


     Q = total rate of flow through unit,  mgd


    C  = influent SS ,  mg/£

-------
     A = effective submerged area,  ft

    d.  Calculate amount of backwash water.
                        BW = (3-6 percent)(Q)(lO )
where

    BW = backwash rate, gpd

     Q = total rate of flow through unit, mga

5-96.  Output Data.
                                    2
    a.  Effective submerged area, ft .
                                             2
    b.  Hydraulic rate of application,  gpm/ft .
                                         2
    c.  Solids rate of application, Ib/ft /day.

5-97.  Example Calculations.

    a.  Calculate effective submerged area of screen.
                     A "
                                                           EM 1110-2-501
                                                             Part  1 of 3
                                                                29 Sep 78
                                     2
                                   ff( 2)060

where
                                     2
     A = effective submerged area, ft

     m = constant, 0.0267

     Q = flow, 1 mgd
     C  = initial resistance, 1.8 ft  (23-micron fabric)

     n = 0.1337
     I = filterability index, 0.5

-------
EM 1110-2-501
Part 1 of 3

29 Sep 78

                                 2
     S = speed of strainer, 20 ft /min


     H = head loss across microscreen, 6 in.
               ..                              1Q6

          A ~                    6(2*060
                              A = 56.7 ft2


    "b.  Calculate hydraulic rate of application.
                                   A(2U)60


where

                               2
    HR = hydraulic rate, gpm/ft


     Q = flow, 1 mgd

                                          2
     A = effective submerged area, 56.7 ft
                            HR =
                                 56.7(2*1)60

                                            2
                           HR = 12.25 gpm/ft


                           led limit
culate area using HR = 6.5 gpm/ft2.
                                                 2
Note:  HR exceeds recommended limit of 6.5 gpm/ft ;  therefore, recal-
                              A =
                              A =
                                  6.5(2^)60


                                          2
                              A = 106.8 ft
     c.   Calculate solids rate of application.

-------
                                                            EM 1110-2-501
                                                              Part  1  of ^
                                                                29  Sep 78
                                  Q(C.)8.3U
                             SR = 	—„	
where
                                          2
    SR = solids rate of application, It /ft /day


     Q = flow, 1 mgd


    C. = influent suspended solids, 20 mg/A

                                 o
     A = area submerged, 106.8 ft


                             OR - 1(20)8.31*
                             SR '   106.8


                          SR = 1.56 Ib/ft2/day

                                                 2
Note:  SR exceeds reconmended limit of 0.88 lb/ft /day; therefore, recal-
culate area using SR = 0.88 Ib/ft2/day.


                                 Q(C )8.3U
                             , _ 1(20)8. 3U
                             A     0.88


                              A = 189.3 ft2
    d.  Calculate amount of backwash water.


                                   "/.i 11 i i i~*
                              BW =
                                     100
where


    BW = backwash rate, gpd


     % = percent, U


     Q = flow, 1 mgd
                                     100

                             BW = 1^0,000 gpd



                                 5-11*5

-------
 EM 1110-2-501
 Part  1  of  3
 29 Sep  78

 5-98.   Cost Data.  Appropriate cost data and economic evaluation may lie
 found in Chapter 8.

 5-99.   Bibliography.

    a.  Bordien D. G. and Stenburg, R. L., "Microscreening Effectively
 Polishes Activated Sludge Effluent," Water and Wastes Engineering
 Vol 3,  Sep 1966, pp 7^-77.                               	

    b.  Boucher, P. L. , "A New Measure of the Filtrability of Fluids
 with Application to Water Engineering," ICE Journal (British), Vol 27
 No. k,  19U7, PP U15-UU6.

    c.  Burns and Roe, Inc., "Process Design Manual for Suspended Solids
 Removal," prepared for the U. S.  Environmental Protection Agency, Tech-
 nology  Transfer, Oct 1971, Washington, D. C.

    d.  Culp, R. L. and Gulp, G.  L., Advanced Wastewater Treatment,
 Van Nostrand, New York, 1971.          ~~  ~

    e.  Engineering-Science, Inc., "State of the Art of the Micro-
 screen  Process," prepared for the Federal Water Quality Administration,
 Contract No.  11+-12-819, Jul 1970, Washington, D. C.

    f.  Engineering-Science, Inc., "Theoretical Formulation of
 Operational Model for Simulation of Microscreen Behavior, Report No.
 B-l, Sep 1970, Federal Water Quality Administration, Washington, D. C.

    g.  Engineering-Science, Inc., "Current State of Operational Model
 for Simulation of Microscreen Behavior," prepared for the Federal Water
 Quality Administration,  Contract  No.  ll*-12-8l9, Nov 1970, Washington,
 D •  0 i

    h.  Engineering-Science, Inc., "Development of Field Data
Acquisition Program for Pilot-Scale Microscreens," prepared for the
 Federal Water Quality Administration,  Contract No. lU-12-819, Jan 1971,
Washington, D. C.

    i.  Engineering-Science, Inc., "investigation of Response Surfaces
of the Microscreen Process," Report No.  17090EEM, Dec  1971, U.  S.  En-
vironmental Protection Agency,  Washington,  D.  C.

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29  Sep  78;

    j.  Lyman, B. ,  Ettelt, G. ,  and McAloon," T. ,  "Tertiary Treatment at
Metro Chicago by Means of Rapid Sand Filtration  and Microstrainers,"
Journal, Water Pollution Control Federation, Vol Ul, Feb 1969,
pp
    k.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection,
Treatment, and Disposal, McGraw-Hill, New York, 1972.

    1.  Mixon, F. 0., "Filterability Index and Microscreener Design,"
Journal, Water Pollution Control Federation, Vol ^2, No. 11, Nov 1970,
pp 19^-1950.

-------
EM 1110-2-501
Part 1 of  3

29 Sep 78
              Table  5-24.   Suggested Removals  from Secondary
                         Effluents by Microscreens
Fabric Aperture
microns
23
35
Anticipated Removal, %
Suspended Solids
70 to 80
50 to 60
BOD
60 to 70
40 to 50
Flow, gpm/ft2
of Submerged Area
6.7
10.0
                                                          From Gulp and Gulp, 1971
              Table 5-25.   Microscreen Sizes  Available from
                            Glenfield and Kennedy


Motors
Drum Sizes, ft
Diameter
5
5
7-1/2
10
Width
1
3
5
10
Drive
1/2
3A
2
h
, bhp
Wash
Approximate
Ranges
Pump Capacity
1
3
5
7-1/2
0.
0.
0.

05
3
8
3
to
to
to
to
of
, mgd
0.5
1.5
4
10
for
Recommended
Maximum Flow
Tertiary Sewage
Applications, mgd
23 microns
0.
0.
0.
2.
075
20
70
00
35 microns
0.
0.
1.
3.
11
30
00
00
                                                           From Culp and Gulp, 1971
                      Table 5-26.  Microscreen-Sizes
                              (Zurn Industries)
Drum Sizes,
Diameter
k
U
6
6
6
10
ft
Width
2
U
k
6
8
10
Screen Area
ft2
2k
48
72
108
144
315
                                                From Gulp and Culp, 1971
                                   5-148

-------
                                                          EM 1110-2-501
                                                            Part 1 of  3
                                                              29 Sep 78>
                        Section XIV.   DRYING  BEDS
5-100.   Background.
    a.
    c,.  Sj-udge drying beds (fig.  5-15)  are a common means  of dewatering
digested sludges, particularly for small plants.   Drying beds normally
consist of U-9 in. of sand over 8-18 in. of graded gravel  or stone.   The
beds are provided with underdrains spaced 9-20 ft apart.  Underdrain
piping is often vitrified clay with open joints,  having a  minimum di-
ameter of U in. and a minimum slope of about 1 percent. Wet sludge  is
usually applied to the drying beds in layers of 8-12 in.

    b.  Design and use of drying beds for sludge dewatering are affected
by weather conditions, sludge characteristics, land value, proximity of
residences, use of sludge conditioning aids, and subsoil permeability.
Sludge bed loadings can be computed on a per capita basis.  Table 5-27
summarizes typical loading rates for various sludges.  Drying beds may
be open to the atmosphere or covered with glass or clear plastic.
    c.
    ..  Due to potential odor problems, sludge drying beds should be
covered.  Bed inclosures protect the beds from rain, help control odors
and insects, reduce the drying period, reduce land requirements, and
improve the appearance of the waste treatment facility.

5-101.  Input Data.

    a.  Sludge flow, gpd.

    b.  Solids in thickened  sludge, percent.

    c.  Solids desired, percent.

5-102.  Design Parameters.

    a.  Depth of sludge applied  (8-12  in.).

    b.  Days  (T) in which  drainage  is  the primary drying  mechanism
 (1-8  days).

     c.  Solids after  T days  (15-25$).

     d.  Clearwater evaporation rate (available  from the U.  S.  Weather
Bureau).

-------
EM 1110-2-501
Part  1 of  3
29  Sep 78












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  CLASS-COVER
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   WALK
 •6-IN. FINE SAND
 3-IN. COARSE SAND
 3-IN. FINE GRAVEL
 .3-IN. MEDIUM GRAVEL
 .3 TO 6-IN. COARSE GRAVEL
               3-IN. MEDIUM GRAVEL
        "2-IN. COARSE SAND

             6-IN. UNDERDRAIN LAID\/
               WITH OPEN JO/NTS   f

      SECTION A-A
        Figure 5-15-   Schematic  of a typical  sludge  drying  bed.

                                     5-150

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep  78
    e.  Correction of evaporation rate for1 sludge (^0.75).
    f.   Average rainfall in wet month (available from the U.  S.  Weather
Bureau).

    g.   Fraction of rainfall absorbed by the sludge (MD.57)-

    h.   Number of sections desired.

5-103.   Design Procedure.  Fill several columns with thickened/digested
sludge to desired application depth.   The bottom of the column should
contain sand and gravel in similar depths to that expected in the bed.
Check the bed daily until drainage from the bottom has essentially
ceased*.  Record the number of days of drainage (t ) and the percent
solids in the sludge(s).

    a.   Calculate the required drying time.

                         30 x H x so,       ,

                     1 "   aE - bR  lsi   S2 I   ^d

where

     T = total drying time, days

     H = depth to which sludge is applied, in.

    S  = initial solids, percent
     o
     a = correction of evaporation rate for sludge, 2iO«75

     E = clearwater evaporation rate, in./month

     b = fraction of water absorbed by sludge, 2i°-57

     R = rainfall during wet month, in./month

    S  = solids content after  t   days, percent

    S  = final solids content, percent

    t,, = time during which drainage is significant, days
     d
                                 5-151

-------
 EM 1110-2-501
 Part  1  of  3
 29  Sep  78

    b.   Calculate the surface area.

                                 Q  x T(12)
                            SA = -

where
                                  2
    SA =  surface area required, ft

    Q  =  volumetric sludge flow, gpd
     S

The drying bed is divided into several sections which are filled in turn
so that one is always available to accept additional sludge.
where

    N = number of sections

The area of each section can be given by


                                 ^ = r
where

    AS = the area of each section, ft

    c.  Calculate the solids produced.
           DTPY . Vo               (365 days/yr)

where

    DTPY = tons of dry solids per year

    d.  Calculate weight of solids removed.

                                     DTPY
where
                               TPY =
                                      S2
                                5-152

-------
    TPY = total tons  per year removed.


5-10H.   Output Data.

                         2
    a.   Area required, ft


    b.   Depth of sludge application,  in.


    c.   Number of sections.

                                2
    d.   Area of each section, ft


    e.   Drying time in bed,  days


5-105.   Example Calculations.


    a.   Calculate the required drying time.


                          30(H)S
                      m =

                          aE - bR
where
     T = total drying time, days


     H = depth of sludge applied, 12 in.


    S  = initial solids content, 2.5 percent
     o

     a = correction for evaporation, 0.75


     E = clearwater evaporation rate, h in. /month


     b = fraction of rainfall absorbed, 0.57


     R = rainfall of wet month, 2 in. /month


    S  = solids content after  t   days, 20.0 percent


    S  = final solids content, 30 percent


    t, = time in which drainage is significant, 6 days
                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                               29 Sep 78
                                 5-153

-------
 EM 1110-2-501
 Part 1 of 3
   29  Sep  78

                  T _     30(12)2.5     /]_   i_
                      0.75(4)  -  0.57(2) \2Q ~  30

                                T =  Ik days

     "b.   Calculate the surface area.

                                  (Q
                             QA =    a	
                                   H(7.48)
 where

     SA =  surface area, ft

     Qg =  sludge flow, 7000 gpd

     H =  depth of sludge applied, 12 in.

     T =  drying time, Ik days


                           oA = (7000)14(12)
                                  12(7.48)

                             SA = 13,102 ft2

    c.   Calculate the solids produced.

                                QSSQ(8.34)(365)
                                   (100)2000
where

     DTPY = tons of dry solids,  tons/year

       Qg = sludge flow,  7,000 gpd

       So = initial solids  content,  2.5  percent

     8.34 = conversion factor, lb  to gal

      365 = days per year

     2000 = Ib/ton

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                29 Sep 78
                       TVTPY - 7000(2.5)8.3M 365)
                       DTPY "    (100)2000

                          DTPY =266 tons/year


    d.  Calculate the weight of solids removed.


                                     DTPY
                               TPY = =±£±


where

     TPY = tons per year removed

    DTPY = tons of dry solids per year, 266

      S  = final solids content, 0.30


                                TPY = 26°
                                      0.30

                           TPY = 86? tons/year


5-106.  Cost Data.  Appropriate cost .data and economic evaluation may
be found in Chapter 8.

5-107.  Bibliography.

    a.  American Society of Civil Engineers and-the Water Pollution
Control Federation, "Sewage Treatment Plant Design," Manual of Practice
No. 8, 1959, 1961, 1967, 1968, Water Pollution Control Federation,
Washington, D. C.

    b.  Bowers, M., "Tips on Sludge Drying Beds Care," Sewage and
Industrial Waters, Vol 29, No. 7, Jul 1957, PP 835-836.

    c.  Burd, R. S.,  "A Study of Sludge Handling and Disposal," Publi-
cation WP-20-**, May 1968, Federal Water Pollution Control Administration,
Washington, D. C.

    d.  Eckenfelder,  W. W., Jr., Water Quality Engineering for Prac-
ticing Engineers,  Barnes and Nobel, New York, 1970.


                                 5-155

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EM 1110-2-501
Part 1 of 3
29 Sep 78

    e.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection,
Treatment, and Disposal, McGraw-Hill, New York, 1972.

    f.  Smith, R. , "Preliminary Design of Wastewater Treatment Systems,"
Journal, Sanitary Engineering Division, American Society of Civil
Engineers, Vol 95 SA1, 1969, pp 117-118.

    g.  Vesilind, P.  A., Treatment of Wastewater Sludges, Ann Arbor
Science Publishers, Inc., 1975.

    h.  Walski, T.  M., "Mathematical Model Simplifies Design of Sludge
Drying Beds," Water and Sewage Works, Vol 123, No.  U, April 1976,
pp 6*1-65.
                                 5-156

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                               Table 5-27

                  Area Required for Sludge Drying Beds

                      in the Northern United States
                                                           EM 1110-2-501
                                                             Part 1 of 3

                                                               29 Sep 78
        Type of Sludge
Primary digested


Primary and humus digested


Primary and activated digested


Primary and chemically precip-
  itated digested
 Open Beds
   2
 ft /capita


1.0  to 1.5


1.25 to 1.75


1.75 to 2.5


2.0  to 2.5
Covered Beds
   2
 ft /capita


0.75 to 1.0


1.0  to 1.25


1.25 to 1.5


1.25 to 1.5
                                                    (next page is 5-159)
                                 5-157

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
                        Section XV.   POSTAERATION
5-108.   Background.   Postaeration is increasingly required by many
state pollution control agencies for the purpose of maintaining certain
dissolved oxygen concentrations in wastewater treatment plant effluents.
Postaeration can be accomplished either in a separate aeration tank
equipped with a diffused or mechanical aeration system or by cascade
aeration.

5-109-   Mechanical or Diffused Aeration.

    a.   Design of Aeration Tank.

    (l)  Input data.

    (a)  Average wastewater flow.

    (b)  Peak wastewater flow.

    (2)  Design parameter.  Detention time (5-10 min).

    (3)  Design procedure.  Calculate the volume of the aeration tank.
                                         1
                                         j
                               V =


where

     V = volume of aeration tank, million gal

    Q  = peak daily flow, mgd

     t = detention time, min (5-10 min)

    b.  Design of Diffused Aeration System.

    (l)  Design parameters.

    (a)  Standard transfer efficiency, percent,  from manufacturer
(5-8 percent).

    (b)  0  transfer in waste/0? transfer in water,  0.9.
                                 5-159

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EM 1110-2-501
Part 1 of 3
 29  Sep  78

    (c)  0  saturation in waste/0  saturation in water,  0.9.

    (d)  Correction factor for pressure,  1.0.

    (2)  Select summer operating temperature (25°-30°C)  and determine
(from standard tables) 0  saturation.

    (3)  Adjust standard transfer efficiency to operating conditions:

                           (C ) (8)(p)  -  C
                 OTE = STE   S 1    - ±1 a(l.02)T"20

where

      OTE = operating transfer efficiency, percent

      STE = standard transfer efficiency, percent

    (C  )  = saturation at selected summer temperature T, °C,  mg/&
      i3 J-

        3=0  saturation in waste/0  saturation in water, %0.9

        p = correction factor for pressure, %1.0

       C  = minimum dissolved oxygen to be maintained in the basin,
            2.0 mg/£

        a = 0  transfer in waste/0? transfer in water, 0.9

        T = temperature, °C

    (U)  Calculate required air flow:
                  R  =
                   a                Ib
                       (OTE)0.0176
                                     0
                                   ft3 air      day
where

     R  = required air flow, 20 to 30 cfm/1000 ft3
      9-


                                 5-160

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                              29 Sep 78

     0  = oxygen required, Ib/day

    OTE = operating transfer efficiency, percent

      V = volume of basin, gal

    (5)  Check horsepower for complete mixing against horsepower required
for complete mixing >_0.1 hp/1000 gal; select the larger horsepower.

    c .  Design of Mechanical Aeration System.

    (l)  Design parameters.

    (a) ' Standard transfer efficiency, Ib/hp-hr (0 dissolved oxygen,
20°C, and tap water).

    (b)  0  transfer in waste/0  transfer in water, 0.9.

    (c)  02 saturation in waste/0  saturation in water, 0.9.

    (d)  Correction factor for pressure, 1.0.

    (2)  Select summer operating temperature (5°-30°C), and determine
(from standard tables) 0  saturation.

    (3)  Adjust standard transfer efficiency to operating conditions.
where
                           (Cs) (0)(p) - C
                 OTE = STE -      - - a(l.02r
      OTE = operating transfer efficiency, Ib 0 /hp-hr

      STE = standard transfer efficiency, Ib 0 /hp-hr

    (Cs)  = 0  saturation at selected summer temperature T,  °C,  mg/£

        3=0  saturation in waste/0  saturation in water,  0.9

        p = correction factor for pressure, 1.0

       C  = minimum dissolved oxygen to be maintained in the basin,
            2.0 mg/Jl
                                 5-161

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EM 1110-2-501
Part 1 of 3
29 Sep 78

        a = 0  transfer in waste/0  transfer in water, 0.9

        T = temperature, °C

    (k)  Calculate horsepower requirement.
where

     hp = horsepower, per 1000 gal

     0  = oxygen required, Ib/day

    OTE = operating transfer efficiency

      V = volume of basin, gal

    (5)  Check horsepower for complete mixing against horsepower required
for complete mixing >0.1 hp/1000 gal; select the larger horsepower.

    d.  Output Data.

    (l)  Diffused aeration system.

    (a)  Standard transfer efficiency, percent.

    (b)  Operating transfer efficiency, percent.
                                       o
    (c)  Required air flow, cfm/1000 ft .

    (2)  Mechanical aeration system.

    (a)  Standard transfer efficiency, Ib 0 /hp-hr.

    (b)  Operating transfer efficiency, Ib 0 /hp-hr.

    (c)  Horsepower required.

    (3)  Aeration equipment.

    e.  Example Calculations.

                                5-162

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                29 Sep 78
     (l)  Design of aeration tank.
                                   60(24)
where

     V = volume of aeration tank, million gal

    Q  = peak flow, 2 mgd

     t = detention time, 5 min


                               y-
                                   60(2*0

                    V = 0.007 million gal = 7000 gal

    (2)  Design of diffused aeration system.

    (a)  Adjust standard transfer efficiency to operating conditions

                           (C ) g(p) - C
                 OTE = STE   5 1    - ± a(l.02)T~20

where

      OTE = operating transfer efficiency, percent

      STE = standard transfer efficiency, 8 percent

    (C )   = saturation at temperature T, 8.2  mg/£

        0 = 0.9

       p = pressure correction factor,  1.0

       a = 0.9

       T = temperature,  25°C

       C   = minimum dissolved oxygen,  2  mg/SL

     9.17 = saturation at  20°C
                                 5-163

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EM 1110-2-501
Part 1 of 3
  29 Sep  78

                               OTE = 4.7$

    (b)  Calculate required air flow.
                   R  =
                                 02(105)7.48
                    'a                lb 0
                        (OTE)0.01T6      d  1440 frf V
                                    ftj air        y

where
                                                      •3
     R  = required air flow for mixing, 25 cfm/1000 ft
      a
     Q  = oxygen required, Ib/day

    OTE = operating transfer efficiency, 4.7 percent

      V = volume of basin, 7000 gal
                       25 =
                            4.7(0.0176)lU4o(2000)
                        0  required =2.79 Ib/day
     (c)   Check horsepower for mixing.
 where

      hp = horsepower required

      0_ = oxygen required,  27-9  Ib/day

     OTE = operating transfer efficiency,  4.7 percent

       V = volume of tank,  2000 gal


                                  5-164

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep  78


                            hp =    2T.9
                             *   >*.7(2*07000

                         hp = 0.035 hp/1000 gal

Therefore, use hp required for mixing.

                          hp = 0.1 hp/1000 gal

    (3)  Design mechanical aeration system.

    (a)  OTE is same as for diffused aeration system = \.1%

    (b)  hp for oxygen requirements = 0.035 hp/1000 gal

    (c)  Use hp = 0.1 hp/1000 gal

5-110.  Cascade Aeration.   Cascade aeration takes advantage of the
principle that reaeration occurs when water flows over a dam or a weir
and turbulent flow takes place.   Oxygen is transferred from the atmo-
sphere.  Head requirement depends upon the initial dissolved oxygen and
the desired dissolved oxygen.

    a.  Input Data.

    (l)  Water temperature,  °C.

    (2)  Initial dissolved oxygen concentration,  mg/£.

    b.  Design Parameters.

    (l)  Desired oxygen concentration,  mg/£.

    (2)  constants   n  and m

    (a)  n =  water  quality parameter  =0.8 for wastewater  treatment
             plant  effluent

    (b)  m =  weir geometry parameter

         1.0  for  a  free weir

         1.3  for  step weirs
                                5-165

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EM 1110-2-501

Part 1 of 3

29 Sep 78


    c.  Design Procedures.   Use equation developed "by Barrett et al.

(para 5-112a).



    (l)  Calculate oxygen saturation,  C  ,  at the selected design

temperature.



                  C  = (lU.562 - 0.*a02T + O.OOT910T2)
                   s


where



    C  = dissolved oxygen saturation at the selected temperature, mg/£
     O


     T = temperature



    (2)  Calculate the deficit ratio, r.



                                   C  - C
                               r =
                                   C  - C^
                                    s    b

where



     r = deficit ratio



    C  = oxygen concentration above the weir, mg/£
     3>


    C  = oxygen concentration below the weir, mg/£



    (3)  Calculate the required head, h.
                        h=
                            0.11 n(m)(l + O.OU6T)


where



    h = required head, ft



    n = water quality parameter



      = 0.8  for wastewater treatment plant effluent



    m = weir geometry parameter



      = 1.0  for free weir



      =1.3  for step weirs



                                 5-166

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                                                            EM 1110-2-501

                                                              Part  1 of 3

                                                               29 Sep  78
     T  =  temperature




     d.   Output  Data.





     (l)   Initial  dissolved  oxygen  concentration,  C   , mg/£.

                                                  3.



     (2)   Final  dissolved oxygen concentration, C  , mg/£.




     (3)   Design temperature,  T ,  °C.




     (1|)   Required head,  h  , ft.




     e.   Example Calculations.




     (l)   Calculate oxygen saturation,  C
                                        S




                   C  = (111. 562 -  0.4102T + 0.00791T2)
                    o



where




     C  =  oxygen saturation, mg/£
     S



     T = temperature, 25°C






                C  = [iH.562 - O.lil02(25) + 0.00791(25)2]
                  S





                             c  = 9.25
    (2)  Calculate deficit ratio.



                                   C  - C
                                   C  - C

where                               s    D




     r = deficit ratio




    C  = oxygen saturation, 9.25 mg/£
     S




    Ca = oxygen concentration above weir, 2.0 mg/£




    C^ = oxygen concentration below weir, 5.0 mg/£








                                5-167

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EM 1110-2-501
Part 1 of 3
29 Sep 78
                               = 9.25 - 2.0
                                 9-25 - 5.0
                                 r = 1.7

    (3)  Calculate required head.
                                         O.OU6T)

where

    h = required head, ft

    r = deficit ratio, 1.7

    n = water quality parameter, 0.8

    m = weir geometry parameter, 1.3

    T = temperature, 25°C

                                   1.7 - 1
                     h   0.11(0.8)1.3[1 + O.OU6(25)]

                               h = 2.85 ft


 5-111.  Cost D_a_ta.  Appropriate cost data and economic  evaluation may be
 found  in  Chapter 8.

 5-112.  Bibliography.

     a.  Barrett, M.  J.  et  al., "Aeration Studies  for Four  Weir  System,"
 Water  and Water Engineering,  6k, No.  9, I960, pp  U07A13.

     b.  Roy F. Weston,  Inc.,  "Upgrading Existing  Wastewater  Treatment
 Plant," Process Design  Manual for Environmental Protection Agency,
 October 1971-
                                 5-168

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78

              Section XVI.  SLUDGE HAULING AND LANDFILLING

 5-113.  Background.

    a.  General.  Landfilling can provide an acceptable and inexpensive
 method for ultimate sludge disposal, particularly for smaller facilities.
 The method may be of special importance if it can be integrated with
 solid waste disposal systems that have an operating sanitary landfill.
 Other methods of sludge treatment, such as drying beds or incineration,
 are considered to be methods of volume reduction that produce a residue
 requiring ultimate disposal.

    b.  Principles of Operation.

    (l)  Sludge hauling and landfilling may be approached in a manner
 similar to that for a typical solid waste disposal problem.   Most solid
 waste disposal systems have at least four definable components:   storage,
 collection, haul, and disposal.   In addition, sludge disposal systems
 usually require some form of pretreatment if associated costs are to be
 minimized.

    (2)  Pretreatment of sludge is related to reducing the volume to a
 minimum before transporting.  Typical unit processes used for volume
 reduction may include digestion, centrifugation, vacuum filtration, .and
 sludge drying beds.  Costs associated with these processes are not con-
 sidered to be part of sludge hauling or landfilling but are very impor-
 tant in the overall sludge handling train.

    (3)  Storage costs are site-specific and depend largely upon the
method selected in the sludge handling train.  They may be simply the
 costs associated with the purchase of bins for storage of waste  acti-
 vated or primary sludge, a dump truck for storage of digested sludge
 solids that have been centrifuged or vacuum filtered,  or the  cost asso-
 ciated with sludge drying beds.
         Collection costs are dependent upon a time-labor relationship
to transfer the sludge from storage to the transporting vehicle,  as a
dump or tank truck.  There may not be a collection cost associated with
labor; however, a cost would be incurred to provide a vehicle during the
loading period.  Larger facilities may require that a driver be assigned
to the vehicle during loading periods.   Collection costs may be signifi-
cant when it is necessary to shovel sludge from drying beds  into  trucks
for transportation to the landfill.   As indicated in the above paragraphs
collection costs are site and system specific.


                                 5-169

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EM 1110-2-501
Part 1 of 3
29 Sep 78

     (5)  Transportation costs are associated with such parameters as
truck cost, truck size, haul time, labor, and operating costs per unit
time for items such as depreciation, fuel, insurance, maintenance, etc.
Operating  costs may "be estimated from manufacturer's rating information
and used in conjunction with estimates of sludge production from various
wastewater treatment processes.

     (6)  Disposal costs are related to the operation and management of
the  final  disposal facility.  This cost should be minimal if the fa-
cility will integrate ultimate sludge disposal with the disposal of
refuse.  When this is possible, the disposal costs may only include the
costs of unloading and a landfill fee.  On the other hand, if the land-
fill is to receive only waste sludge; costs may be very significant as
other equipment for operation of the landfill will be required.  The
equipment used for landfill operation may include units for excavation,
placing, covering, and compaction of fill.

     (7)  The lowest possible moisture content attainable at a reasonable
cost should be produced for economical sludge hauling and landfill
operations.  A reduction of moisture content will produce a savings in
storage, initial equipment, operating, and labor costs.

5-II1*.  Input Data.

     a.  Average wastewater flow, mgd.

     b.  Sludge volume, gal/million gal.

     c.  Raw sludge solids concentration, percent.

     d.  Dewatered sludge solids concentration, percent.

     e.  Vehicle loading time, hr.

     f.  Round-trip haul time, hr.

     g.  Vehicle capacity, yd .

     h.  Solids capture in dewatering process, percent.

     i.  Distance to disposal site, miles.
                                  5-170

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78

 5-115-  Design Parameters.

    a.  Sludge volume per million gallons treated (Table 5-28).

    b.  Raw sludge solids concentration (Table 5-28), 1.5-15 percent.

    c.  Concentrated solids (Table 5-28), 6-60 percent.
                            o
    d.  Vehicle capacity, yd /truck.

    e.  Truck loading time, 0.5-2.0 hr.

    f.  Haul time, local conditions.

    g.  Daily work schedule, 6-8 hr.

    h.  Solids capture (Table 5-29), 70-99 percent.

 5-116.  Design Procedure.

    a.  Compute the sludge volume hauled, yd /day.
                           °v ~ (7A8)(27)(CSS)

where

                                   o
      SV = sludge volume hauled, yd /day

    Q    = average wastewater flow, mgd

      SF = sludge flow, gal/million gal (Table 5-28)

      SS = suspended solids in sludge flow,  percent (Table 5-28)

     CSS = concentrated suspended solids from final treatment process,
           percent (Table 5-29)

    b.  Calculate the number of vehicles for collection and hauling of
the sludge.


                               = (SV)(LT + HT)
                                  (HPD)(CAP)
                                5-171

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EM 1110-2-501

Part 1 of 3
 29  Sep  78



where


    NTR = number of trucks required


     LT = loading time, hr (0.5-2.0 hr)


     HT = round-trip haul time, hr (local conditions)


    HPD = work schedule, hr/day (6-8 hr)

                              3               3
    CAP = vehicle capacity, yd /truck (3-12 yd )


    c.  Compute the tons of sludge hauled per day.


                          (Q   )(SF)(SS)(SCAP)(8.3M
                    rncti = 	  S
                                100(CSS)(2000)


where


     TSH = tons of sludge hauled per day


    SCAP = solids capture, percent (Table 5-29)


 5-117.  Output Data.


    a.  Volume of sludge to be dewatered, gpd.


    b.  Initial moisture content, percent.


    c.  Final moisture content, percent.

                                   o
    d.  Volume of sludge hauled, yd /day.

                          3
    e.  Truck capacity, yd  .


    f.  Time to make one load, hr.


    g.  Work schedule, hr/day.


    h.  Number of trucks required.


    i.  Tons of sludge hauled  per day.


    j.  Distance to disposal site, miles.



                                 5-172

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                                                          EM 1110-2-501
                                                            Part 1  of  3
                                                               29 Sep 78
5-118.  Example Calculations.

    a.  Compute the sludge volume hauled.

                                (Q   )(SF)(-SS)
                           °v ~  7.W(27)CSS

where
                                   Q
      SV = sludge volume hauled, yd /day

    Q    = average daily flow, 1.0 mgd

      SF =' sludge flow, 2700 gal/million gal

      SS = suspended solids in sludge flow, 6 percent

     CSS = concentrated suspended solids from final treatment process,
           12 percent

                                  1.0(2700)6
                             bV   7-^8(27)12


                             SV = 6.7 yd /day


    "b.  Calculate number of vehicles required.


                               _ (SV)(LT + HT)
                                   HPD(CAP)
where

    NTR = number of trucks required

     SV = sludge volume hauled, 6.7 yd /day

     LT = loading t ime, 1.5 hr

     HT = round-trip haul time, 2.5 hr

    HPD = work schedule, 8 hr


                                 5-173

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EM 1110-2-501
Part 1 of 3
29 Sep 78

    CAP = vehicle  capacity,  ^ yd/truck
                                     + 2.5)
                                  8


                       NTR = 1 truck at 2 trips /day


    c.  Compute tons of sludge hauled per day.


                            QQir (SF)SS(SCAP)(8.3U)
                      TSH =    "
                                 100(CSS)2000


where

     TSH = tons of sludge hauled per day

    Qa   = average flow, 1.0 mgd

      SF = sludge flow, 2700 gal/million gal

      SS = suspended solids in sludge flow, 6 percent

    SCAP = solids capture, 95 percent

     CSS = cake suspended solids, 12 percent


                        TSH = 1-°(2TOO)6(95)8.3^
                                 100(12)2000


                        TSH =5.3 tons /day


5-119-  Cost Data.  Appropriate cost data and economic evaluation may be
found in Chapter 8.

5-120.  Bibliography.

    a.  Clark, R.  M.  and Helms, B.  P., "Fleet Selection for Solid Waste
Collection Systems,"  Journal,  Environmental Engineering Division,
American Society of Civil Engineers, Vol 98, No. 71, 1972.


                                 5-17^

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                                                           EM 1110-2-501
                                                             Part 1 of 1
                                                              29  Sep  78

    b.  Clark, R. M. and Gillean, J. I., "Systems Analysis and Solid
Waste Planning," Journal, Environmental Engineering Division, American
Society of Civil Engineers, Vol 100, No. 7, 197*+.

    c.  Guarino, C. F. et al., "Land and Sea Solids Management Alter-
natives in Philadelphia," Journal, Water Pollution Control Federation,
Vol U7, No. 2551, 1975.

    d.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection,
Treatment, and Disposal, McGraw-Hill, New York, 1972.

    e.  Parkhurst, J. D. et al., "Dewatering Digested Primary Sludge,"
Journal, Water Pollution Control Federation, Vol U6, No. U68, 197^.

    f.  U. S. Environmental Protection Agency, Technology Transfer,
Process Design Manual for Sludge Treatment and Disposal, October 197*+.
                                 5-175

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EM 1110-2-501
Part 1  of 3
29 Sep  78
           Table 5-28.   Normal Quantities of Sludge Produced by
                        Different Treatment Processes
Waste-water Treatment Process
Primary sedimentation
Undigested
Digested in separate tanks
Trickling filter
Chemical precipitation
Primary sedimentation and
activated sludge
Undigested
Digested in separate tanks
Activated sludge
Waste sludge
Septic tanks, digested
Imhoff tanks, digested
Gallons
Sludge/
mg
Treated
2,950
1,^50
7^5
5,120
6,900
2,700
19,^00
900
500
Solids
percent
5.0
6.0
7.5
7.5
k.O
6.0
1.5
10.0
15.0
Sludge
Specific
Gravity
1.02
1.03
1.025
1.03
1.02
1.03
1.005
1.0k
1.0k
             Table 5-29-  Process Efficiencies for Dewatering
                            of Wastevater Sludge
Unit Process
Centrifugation
Solid bowl
Disc-nozzle
Basket
Dissolved air flotation
Drying beds
Filter press
Gravity thickener
Vacuum filter
Solids Capture, percent
80-90
80-97
70-90
95
85-99
99
90-95
90+
Cake Solids, percent
5-13
5-7
9-10
k-6
8-25
kO-60
5-12
28-35
                             From EPA Process Design Manual for Sludge Treatment and Disposal
                                   5-176

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                              29 Sep 78

               Section XVII.  MULTIPLE-HEARTH INCINERATION

5-121.  Background.  The multiple-hearth furnace is the most widely used
wastewater sludge incinerator in use today because it is simple to
operate, durable, and capable of burning a wide variety of materials.
Reasonable fluctuations in the feed rate may be accommodated without
interruption of the incineration process.  Figure 5-l6 represents a
typical cross section of a multiple-hearth incinerator.  Sludge from
water or wastewater treatment is normally thickened and dewatered by
vacuum filtration and/or centrifugation.  The dewatered sludge enters
the multiple-hearth furnace at the top and is held first on the top
hearth.  The sludge is stirred constantly to promote drying and burning
by rabble arms.   These slow-moving arms move the sludge across the
hearths to the inner or outer edge where it drops to the hearth beneath.
This process continues until the sludge reaches the bottom of the fur-
nace as ash.

5-122.  Input Data.

    a.  Average wastewater flow, mgd.

    b.  Sludge volume, gal/million gal.

    c.  Raw sludge concentration, percent solids.

    d.  Dewatered sludge concentration, percent solids.
                                         2
    e.  Wet sludge loading rate, Ib/hr/ft .

5-123.  Design Parameters.

    a.  Sludge volume per million gal treated (Table 5-30).

    b.  Raw sludge concentration, percent solids (Table 5-30), 1.5-
15 percent.

    c.  Dewatered sludge concentration, percent solids (Table 5-31),
U-60 percent.

    d.  Design multiple-hearth furnace wet sludge loading rate, 7-12 lb/
hr/ft2 at 20-25 percent total solids.
                                 5-177

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EM 1110-2-501
Part 1  of 3
29 Sep  78
                                             COOLING AIR DISCHARGE
      FLUE GASES OUT
         DRYING ZONE
     COMBUSTION ZONE
         COOLING ZONE
        ASH DISCHARGE
                                                              INLET
                                                            RABBLE ARM
                                                            AT EACH HEARTH
                                                             COMBUSTION
                                                             AIR RETURN
                   COOLING AIR FAN"

              Figure  5-l6.   Typical multiple-hearth  furnace.
                                    5-178

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                                                          EM 1110-2-501
                                                            Part  1  of  3
                                                              29  Sep 78
        Design Procedure.

    a.  Calculate the pounds of dry solids in sludge flow per day.

                          (Q   )(SF)(SS)(SCAP)(8.3U)
                     Dr ~         (100)(100)

where

      SP = dry solids produced per day, lb

    Q    = average wastewater flow, mgd

      SF = sludge flow, gal/million gal (Table 5-30)

      SS = suspended solids flow to dewatering process, percent

    SCAP = solids capture, percent (Table 5-31)

    b.  Calculate the dry solids loading rate.

                            _ (WSLR)(PSTMHF)(2iQ
                         LR ~        100


where
                                               2
        LR = dry solids loading rate, Ib/day/ft
                                              2
      WSLR = wet sludge loading rate, Ib/hr/ft

    PSTMHF = percent solids in sludge to multiple-hearth furnace

    c.  Calculate total hearth area requirement.
                                      LR

                                          2
where   SA = required total hearth area, ft

     d.  From Table  5-32,  select the next larger standard size of
multiple-hearth  furnace and enter data for final design.

                                 5-179

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78
                            THA = xxxx.x  ft2
                             O.D. = xx. xx ft

                           No. of hearths = xx

                           No. of furnaces = x

where  THA = total hearth area furnished

    e.  Calculate combustion air blower horsepower required.

                       PRTTP - (0.15)(WSLR)(THA)2H
                       U3KP          _


where

    CBHP = combustion air blower horsepower required

    0.15 = horsepower required per ton of wet sludge per day at 1-psig
           pressure

    f .  Calculate combustion air blower SCFM supplied.
                      CBSCFM =
                                      2000


where

    CBSCFM = combustion air blower SCFM supplied

      22.5 = SCFM required per ton of wet sludge per day at 1-psig
             pressure

    g.  Calculate cooling air fan horsepower requirements.


                       PTHP - (0-08)(WSLR)(THA)2U
                       CLHP -        2000 -


where

    CLHP = cooling air fan horsepower required


                                 5-180

-------
                                                          EM 1110-2-501

                                                            Part  1  of  3
                                                               29 Sep 78


    0.08 = horsepower required per ton wet sludge per day at 8-in. water

           static pressure


    h.  Calculate cooling air fan SCFM supplied.



                             - (36'.0)(WSLR)(THA)2H
where


    CLSCFM = cooling air fan SCFM supplied


      36.0 = SCFM required per wet ton sludge per day at 8-in. water

             static pressure


5-125.  Output Data.


    a.  Raw sludge concentration, percent solids.


    b.  Dewatered sludge concentration, percent  solids.


    c.  Dry solids produced per  day, l"b.

                                         2
    d.  Dry solids loading rate, Ib/hr/ft  .

                                       2
    e.  Required total  hearth  area,  ft  .

                                        2
    f.  Total  hearth  area furnished, ft  .


    g.  Outside diameter, ft.


    h.  Number of hearths.


    i.  Number of furnaces.


    J.  Combustion  air  blower  horsepower  required,  hp.


    k.  Combustion  air  blower  SCFM supplied,  SCFM.


    1.  Cooling air fan horsepower required,  hp.


    m.  Cooling air fan SCFM supplied, SCFM.
                                  5-181

-------
 EM 1110-2-501
 Part 1 of 3
 29  Sep  78

 5-126.  Example Calculations.


     a.  Calculate the pounds of dry solids produced per day.



                              Q   (SF)SS(SCAP)8.3U
                         SP =   • °	7-	—
                                    100(100)

 where


       SP =  dry solids produced per  day, Ib


     Q    =  average flow,  1.0 mgd


       SF =  sludge flow,  2700 gal/million  gal


       SS =  suspended  solids  in sludge flow, 6 percent


     SCAP =  solids capture, 95  percent



                          SP  =  1-0(6)2700(95)8.31*
                                    100(100)


                          SP  =  128U  Ib/day



    b.   Calculate the dry solids loading rate.


                          Tn    (WSLR)(PSTMHF)2U
                          LR         100


where

                                               f-}
        LR = dry  solids loading rate, Ib/day/ft


      WSLR = wet solids loading rate, 8.5 lb/hr/ft2


    PSTMHF = percent solids to MHF,  12  percent


                          TR - 8.3(12)21;
                          LR	loo—
                                 5-182

-------
                          LR = 2U.5 Ib/day/ft


    c.  Calculate total hearth area required.


                                 SA = LR

where
                                       2
    SA = required total hearth area, ft

    SP = solids produced, 12.Bh Ib/day

    LR = loading rate, 2U.5 Ib/day/ft
                              0/1 ~  2^75


                              SA = 52.U ft2


    d.  Select next larger size hearth.

Use

                TEA = 85 ft2

               O.D. = 6.75 ft

     Wo.  of hearths = 6

    Wo. of furnaces = 1

    e.  Calculate  combustion air horsepower required.


                        rmui, - 0.15(WSLR)THA(2U)
                        CBHP -        2000


where

    CBHP  = combustion horsepower


                                 5-183
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                              29 Sep 78
                                             2

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EM 1110-2-501
Part 1 of 3
29 Sep 78
     0.15  =  horsepower  required  per  ton  of wet  sludge

     WSLR  =  wet  sludge  loading rate,  8.5 lb/hr/ft2

     THA  =  total hearth area, 85 ft2
                         CBHP = 0-15(8.5)85(21+)
                                     2000
                         CBHP = 1.3 hp


    f.  Calculate combustion air blower SCFM.


                       CBSCFM = 22
                                       2000

where

    CBSCFM = combustion SCFM

      22.5 = required SCFM per ton of wet sludge

      WSLR = wet sludge loading rate, 8.5 lb/hr/ft2

       THA = total hearth area, 85 ft2
                        CBSCFM = 22-5(8.5)85(2lQ
                                       2000
                        CBSCFM =  195  cfm
    g.   Calculate  cooling air  fan horsepower requirements.
                       CLHP = °•°8(WSLR)(THA)2U
                                    2000
                                5-1814

-------
                                                          EM 1110-2-501


                                                            Part 1 of 3

                                                              29 Sep 7d''
where




    CLHP = cooling horsepower




    0.08 = horsepower required per ton of wet sludge




    WSLR = wet sludge loading rate, 8.5 lb/hr/ft2




     THA = total hearth area, 85 ft2
                         PTHP - 0.08(8.5)85(2lQ
                         CLHP -       —
                         CLHP = 0.7 hp
    h.  Calculate cooling air fan SCFM.
                        CLSCFM = 36(WSLR)THA(2U)
where




    CLSCFM = cooling SCFM




        36 = SCFM required per ton of wet sludge




      WSLR = wet sludge loading rate, 8.5 lb/hr/ft2


                                     2

       THA = total hearth area, 85 ft
                         CLSCFM - 36(8.5)85(21+)
                         CLSCFM -
                         CLSCFM = 312 cfm
5-127.  Cost Data.  Appropriate cost data and economic evaluation may be

found in Chapter 8.
                                 5-185

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78

5-128.  Bibliography.

    a.  Burgess, J. V., "Comparison of Sludge Incineration Processes,"
Process Biochemistry, Vol 3, April 1968, p 27.

    b.  Gray, D. H. and Penessis, C., "Engineering Properties of Sludge
Ash," Journal. Water Pollution Control Federation. Vol Uk, May 1972,
P 8^7.

    c.  Helmenstein, S. and Martin, F., "Planning Criteria for Refuse
Incineration Systems," Combustion, Vol 1*5, May 197^, p 11.

    d.  Loran, B. I., "Burn That Sludge," Water and Wastes Engineering,
Vol 12, October 1975, p 65.               ~~~	 	SL

    e.  Unterberg, ¥., Sherwood, R. J., and Schnerder, G. R., "Com-
puterized Design and Cost Estimation for Multiple Hearth Sludge Incin-
erators," Environmental Protection Agency Publication No. EP 1 16-17070
EBP 07/71, 1971.	
                                5-186

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                                                    EM 1110-2-501
                                                      Part 1 of  3
                                                        31 Jul 78
Table  5-30.   Normal Quantities of Sludge  Produced by-
             Different Treatment Processes
Waste-water Treatment Process
Primary sedimentation
Undigested
Digested in separate tanks
Trickling filter
Chemical precipitation
Primary sedimentation and
activated sludge
Undigested
Digested in separate tanks
Activated sludge
Waste sludge
Septic tanks, digested
Imhoff tanks, digested
Gallons
Sludge/
mg
Treated
2,950
1,^50
7^5
5,120
6,900
2,700
19,kOO
900
500
Solids
percent
5.0
6.0
7.5
7.5
h.o
6.0
1.5
10.0
15.0
Sludge
Specific
Gravity
1.02
1.03
1.025
1.03
1.02
1.03
1.005
I. Ok
1.0k
  Table  5-31.  Process  Efficiencies  for Dewatering
                 of Wastewater Sludge
Unit Process
Centrifugation
Solid bowl
Disc-nozzle
Basket
Dissolved air flotation
Drying beds
Filter press
Gravity thickener
Vacuum filter
Solids Capture, percent
80-90
80-97
70-90
95
85-99
99
90-95
90+
Cake Solids, percent
5-13
5-7
9-10
U-6
8-25
1*0-60
5-12
28-35
                     From EPA Process Design Manual for Sludge Treatment and Disposal
                         5-187

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78
             Table 5-32.   Standard Sizes of Multiple-Hearth
                              Furnace Units
               No. of Hearths              6 to  12
               Wall Thickness, in.          13.5
               Outer Diameter (O.D.),  ft   6.75  to  22.25
               Effective  Hearth Area,  ft2  85 to 3120
THA
ft
85
98
112
125
126
i4o
145
166
187
193
208
225
256
276
288
319
323
351
364
383
i
452
510
560
575
672
760
845
857
944
O.D.
ft
6.75
6.75
6.75
7.75
6.75
6.75
7.75
7-75
7.75
9-25
7.75
9.25
9.25
10.75
9.25
9.25
10.75
9.25
10.75
9.25
10.75
10.75
10.75
10.75
14.25
14.25
14.25
16.75
14.25
14.25
No.
Hearths
6
7
8
6
9
10
7
8
9
6
10
7
8
6
9
10
7
11
8
12
9
10
11
12
6
7
8
6
9
10
THA
ft2
988
io4i
1068
1117
1128
1249
1260
1268
l4oo
l4io
1483
1540
1580
1591
1660
1675
1752
1849
1875
1933
2060
2084
2090
2275
2350
2464
2600
2860
3120
O.D.
ft
16.75
14.25
18.75
16.75
14.25
18.75
16.75
20.25
16.75
18.75
20.25
16.75
22.25
18.75
20.25
16.75
18.75
22.25
20.25
18.75
20.25
22.25
18.75
20.25
22.25
20.25
22.25
22.25
22.25
No.
Hearths
7
11
6
8
12
7
9
>
6
10
8
7
11
6
9
8
12
10
7
9
x
11
10
8
12
11
9
12
10
11
12
                                5-188

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                                                            EM 1110-2-501
                                                              Part  1  of  3

                                                                29  Sep 78
               Section XVIII.   FLUIDIZED BED INCINERATION
5-129.  Background.

    a.  Fluidized bed  incineration for waste-water sludges involves the
destruction of waste-water  solids through combustion.  Basically,  de-
watered sludge is pumped into the incineration vessel containing  a
heated catalytic bed.   This  bed is fluidized by a controlled upward air-
flow at pressures of 2.0 to  5.0 psig; this air also supplies oxygen for
combustion.  Temperatures  for combustion range from 1200° to l600°F.
Supplemental fuel may  be added by burners to keep temperatures  at opti-
mum levels if the sludge characteristics do not allow for autogenous
combustion.  Burning of wastewater sludge produces ash and  several gases
which are carried upward by  the flow of air through an exhaust  stack.
Figure 5-17 describes  a typical material balance for incineration of
1 Ib of dry sludge.  Normally, some type of air pollution equipment such
as scrubbers, electrostatic  precipitators, and cyclones  are connected to
process the incinerator byproducts.  This exhaust may also  pass through
other control devices  if noxious odors are expected to result  from
combustion.
                               AUXILIARY FUEL
                                 (NO. 2 OIL)
                                 0.4246 LB.
                                 0.3706 LB. C
                                 0.0533 LB. H
                                 0.0008 LB. S
               f 5.4625 LBS. O2] .
               118.2875 LBS. N2J
              SLUDGE ONE DRY POUND
                0.4363 LB. C
                0.0637 LB. H
                0.0024 LB. S
                0.1400 LB. ASH
                0.3335 LB. O2
                0.0241 LB. N

                H20 2.984 LBS. —
                "IN WETSLUDGE"
                WHICH CONTAINS
                ONE DRY POUND
                SLUDGE
1 EXCESS AIR
T ?n 79«9 1 HC


FLUIDIZED
BED
INCINER-
ATOR
(SANDS)


f 2.7140 LBS. O2|
^18.3116 LBS. N2J
	 *• ASH 0.14 LB.

	 ^- H2O 4.027 LB.


	 *> CO2 2.955 LB.
	 ^- SO2 0.0064 LB.
^
^^^^ SAND GRANULES?
NOx?
             Figure 5-17-  Material balance  for  fluidized bed
                        sewage sludge incineration.
                                  5-189

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78

    "b.  The fluidized bed. incinerator used for combustion of waste-water
sludge is a vertical cylinder with an air distributor plate  containing
small openings near the bottom as seen in Figure  5-l8.   The  base  plate
serves two functions:  (l) allows air to pass  into the media and  (2)
supports the media.  An external air source forces the air into the
bottom of the vessel where it is distributed in such a manner as  to
fluidize the bed and supply oxygen for combustion.

    c.  The bed material is composed of graded silica sand with size
varying from ASTM No. 8 to No. 20.   The normal operating temperatures
for these fluidized sand beds are between 1200° and l600°F,  the maximum
being 2000°F.  At this temperature, the sand approaches its  melting
point which is detrimental to the incinerator  process.   Also, damage to
the incinerator vessel would be experienced in the heat exchanger and
flue piping.

    d.  There are two possible locations for the  sludge feed inlet to
be placed on a fluidized bed incinerator vessel.   One is positioned  so
that the sludge is pumped (screw-type) directly into the fluidized bed.
The advantage of this configuration lies in the fact that complete com-
bustion is realized in a short time.  Yet, problems can be incurred  due
to clogging from dried sludge.  The second location is above the  fluid-
ized bed or the freeboard zone.  Hot gases evaporate the water in the
sludge as the solids enter the vessel.  This operation is more amenable
to combustion of solids with high moisture contents.  However, combus-
tion time for the elevated configuration is increased.

    e.  Sludge combustion in an incinerator occurs in two zones:   Zone  1
(bed) where the principal processes are pyrolysis and combustion  and
Zone 2 (freeboard) where the principal processes  are flame holding and
final burnup.  Combustible elements contained  in  sludge are  carbon,
hydrogen, nitrogen, and sulfur, which when completely burned with oxy-
gen, form the combustion products C02, 1^0, NOX,  and S02, respectively.
Ash is also generated in the process of incinerating sludge.  The NOX,
S02, and particulate ash can be classified as  major air pollutants.   In
order to prevent the release of these by-products into the atmosphere,
all fluidized bed incinerators are equipped with  scrubbers of varying
efficiency.  These units have been found to be quite effective.

    f.  In some cases, an air preheater or heat exchanger can be  used
in conjunction with a fluidized bed as seen in Figure 5-18.   The  func-
tion of the preheater is to raise the temperature of the incoming air to
1000°F by mixing the cool air at 70°F with the exhaust gas at 1500°F.
                                 5-190

-------
                                                      EM 1110-2-501
                                                        Part 1 of  3
                                                            29 Sep  78
            SIGHT GLASS
    EXHAUST
   SAND FEED
 PRESSURE
 TAP
                                               PREHEAT BURNER
ACCESS
DOORS
                                                THERMOCOUPLE
                                          --_       SLUDGE INLET
                                                    FLUIDIZING
                                                    AIR  INLET
     Figure 5-18.  Cross section  of a  fluid bed  reactor.
                            5-191

-------
EM'1110-2-501
Part 1 of 3
 29  Sep  78

5-130.  Input Data.

    a.  Average flow,  Q    ,  mgd.

    b.  Sludge volume, gal/million  gal (Table 5-33).

    c.  Sludge solids concentration,  percent (Table 5-33).

    d.  Moisture content of dewatered sludge, percent  (Table 5-3*0

    e.  Work schedule, hr/day.

    f.  Sludge analysis.

    (l)  Carbon content, percent.

    (2)  Hydrogen content, percent.

    (3)  Oxygen content, percent.

    (k)  Sulfur content, percent.

    g.  Heat value of fuel.

    h.  Fuel analysis, for fuel oil.

    (l)  Carbon content, percent.

    (2)  Hydrogen content, percent.

    (3)  Oxygen content, percent.

    (h)  Sulfur content, percent.

    i.  Operating temperature of preheater, °F.

    j.  Ambient air temperature, °F.

    k.  Sand-to-sludge ratio.

    1.  Specific weight of sand, Ib/ft .

    m.  Volatile solid content of sludge, percent.
                                 5-192

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                              29 Sep 78

    n.  Fuel cost, dollars per million Btu.

5-131.  Design Parameters.

    a.  Sludge solids concentration, 1.5 to 5 percent.

    b.  Moisture content of dewatered sludge, liO to 96 percent.

    c.  Sludge analysis.  Use laboratory values if known;  otherwise use
the following.

    (l)  Carbon content, 1*3.6 percent.

    (2)  Hydrogen content, 6.k percent.

    (3)  Oxygen content, 33.^ percent.

    (4)  Sulfur content, 0.3 percent.

    d.  Heat value of fuel oil, 18,000 Btu/lb.

    e.  Fuel analysis.   Use reported values,  or for fuel oil use the
following.

    (l)  Carbon content, 87.3 percent.

    (2)  Hydrogen content, 12.6 percent.

    (3)  Oxygen content, 0 percent.

    (k)  Sulfur content, 1.0 percent.

    f.  Operating temperature of preheater, 1000°  to 1200°F.

    g.  Incinerator retention time,  10 to  50  sec.

    h.  Ratio of incinerator height:diameter, lt:l  to 6:1.

    i.  Heat release  rate, <50,000 Btu/hr/ft.

    j.   Sand-to-sludge ratio,  3 to 8 Ib/lb/hr.

    k.   Specific  weight  of sand,  110
                                5-193

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78
    1.  Grid jet velocity, >300 fps.
    m.  Volatile solids content of sludge, percent.   Use reported values,
or ^0 to 60 percent volatile.
    n.  Fuel cost, dollars per million Btu.
5-132.  Design Procedure.
    a.  Determine the amount of sludge to be incinerated, It/day.
                          (Q   )(SF)(SS)(SCAP)(8.3^)
                                 (100)(100)
where
      SP = dry sludge produced per day, lb
    Q    = average waste-water flow, mgd
     avg
      SF = sludge flow, gal/million gal (Table 5-33)
      SS = suspended solids in sludge, percent
    SCAP = solids capture, percent (Table 5-3M
    b.  Calculate the sludge hourly loading rate.

                                TR - SP
                                LR ~ Ira
where
     LR = dry sludge loading rate, Ib/hr
    HPD = work schedule, hr/day
    c.  Calculate sludge heat value.

                   BS = 11*5^ + 620
where
    BS = sludge heat value, Btu/lb

-------
                                                            EM 1110-2-501

                                                              Part 1 of 3
                                                               29 Sep 78
     C  =  carbon  in  sludge, percent  (if unknown, use  k3.6)


     R^ =  hydrogen in  sludge, percent  (if unknown, use 6.k)


     QI =  oxygen  in  sludge, percent  (if unknown, use  33.lt)


     BI =  sulfur  in  sludge, percent  (if unknown, use  0.3)


     d.  Calculate sludge loading rate.



                           SL = 10(2-T-0.0222M)



where


     SL =  sludge  loading rate, Ib/ft2/hr


      M = moisture content of dewatered sludge, percent


     e.  Calculate cross-sectional area of incinerator.



                                 A - ^
                                 A~ SL


where   A = area  of incinerator, ft2


     f.  Calculate diameter of incinerator.
where  D = diameter, ft


    g.  Compute auxiliary fuel supply.


    (l)  Calculate "burning rate.



                         BR = 10(5-9Vr-0.0096M)



where  BR = burning rate, Btu/ft2/hr



    (2)  Compute total heat input rate.





                                 5-195

-------
EM 1110-2-501

Part 1 of 3

29 Sep 78



                              HIR = (BR)(A)



where  HIR = total heat input rate, Btu/hr



    (3)  Calculate heat input from sludge.



                             HIS = (BS)(LR)



where  HIS = heat input from sludge, Btu/hr



    (U)  Calculate auxiliary fuel supply.



                             AFS = HIR - HIS



where  AFS = auxiliary fuel supply, Btu/hr



    (5)  Calculate fuel oil required.
                                     HV



where



    FO = fuel oil required, Ib/hr



    HV = heat value of fuel



    h.  Compute air supply rate (20 percent excess air),



    (l)  Calculate air supply rate for sludge.




              q, = 0.0127[(HR)(2.67Cn + 7.9UHn + Sn - 0.
               1                    111.



where  q  = air supply rate for sludge, scfm



    (2)  Calculate air supply rate for fuel.




              q2 = 0.0127[(FO)(2.67C  + 1



where



    q  = air supply rate for fuel, scfm





                                 5-196

-------
                                                            EM 1110-2-501
                                                              Part 1 of 3
                                                                29 Sep 78
     C2 = carbon in fuel,  percent  (if unknown,  use  87.3)

     E^ = hydrogen in fuel,  percent  (if unknown,  use  12.6)

     S2 = sulfur in fuel,  percent  (if unknown,  use  1.0)

     02 = oxygen in fuel,  percent  (if unknown,  use  0.0)

     (3)  Calculate air supply rate.

                                d  = qx + q2

 where   q. = total dry air  supply,  scfm

     i.   Calculate total gas flow  (air plus water).


                                     LE     M
                                  100 - M  3.01

where  a  = total gas flow, scfm

    j.  Calculate air preheater capacity.

    (l)  Calculate the air-to-sludge ratio.
where  ASR = air-to-sludge ratio, Ib air/lb sludge

    (2)  Calculate air preheater capacity.


                     APHS = (0.2U)(ASR)(T2 - T )(LR)


where

    APHS = air preheater capacity, Btu/hr

      T2 = operating temperature, °F (1000° to 1200°F)

      T.^ = incoming air temperature, °F

    k.   Assume a retention time for the incinerator.   (See Table 5-35'


                                 5-197

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78

                            10 <_ at <_ 50 sec

where  dt = retention time, sec

    1.  Determine volume of reactor.

                                ...      dt
                                V= *t 60
                                3
where  V = volume of reactor, ft

    m.  Calculate the height of the reactor.  (U <_ H/D <_ 6)

                                  H = -

where  H = height of reactor, ft.   (if  H/D  does not fall between 1* and
6, adjust  dt  and make a new determination of the volume,  V .)

    n.  Check heat release rate.  (Hr <_ 50,000 Btu/hr/ft)

                                     HIR
                                Hr =
                                      V
                                        3
where  Hr = heat release rate, Btu/hr/ft

    o.  Assume a sand-to-sludge ratio (Table 5-35).  Use 3 to 8 Ib
sand/lb sludge/hr for ASTM No. 8 sand.


                          3 < Rss < 8 Ib/lb/hr

where  Rss = ratio of sand to sludge

    p.  Calculate the depth of ASTM No. 8 silica sand required.

                           T _ (!2)(LR)(Rss)
                                  (TS)(A)

where

     L = depth of sand, in.

    y^ = specific weight of sand, Ib/cu ft (approx 110)
     o

                                 5-198

-------
                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                               29 Sep 78
    q..  Calculate the grid jet velocity (Table 5-35; V > 300 fps).



                          V. = 160 + 160 log L
                           J


where  V. = grid jet velocity, fps
        J

5-133.  Output Data.


    a.  Dry sludge loading rate, lb/hr.


    b.  Sludge heat value, Btu/lb.

                                  2
    c.  Sludge loading rate, Ib/ft /hr.

                                               2
    d.  Cross-sectional area of incinerator, ft .


    e.  Diameter of incinerator, ft.

                            2
    f.  Burning rate, Btu/ft /hr.


    g.  Total heat input rate, Btu/hr.


    h.  Heat input from sludge, Btu/hr.


    i.  Auxiliary fuel supply, Btu/hr.


    j.  Fuel oil required, lb/hr.


    k.  Total dry air supply, scfm.


    1.  Total gas flow, scfm.


    m.  Air preheater capacity, Btu/hr.

                             3
    n.  Volume of reactor, ft .


    o.  Height of reactor, ft.


    p.  Heat release rate, Btu/ft/hr.


    q..  Depth of sand, in.


    r.  Grid jet velocity, fps.



                                 5-199

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EM 1110-2-501
Part I -of 3
 29 Sep 78
     .  Example Calculations.

    a.  Determine the amount of sludge produced.

                             Q   (SF)SS(SCAP)8.3U
                        SP =
                                    100(100)

where

      SP = sludge produced, Ib/day

    Q    = average daily flow, 1.0 mgd
     avg
      SF = sludge flow, 2700 gal/million gal

      SS = suspended solids in sludge, 6 percent

    SCAP = solids capture, 95 percent

                              1.0(2700)6(95)8.3if
                                   100(100)

                            SP = 128J4 Ib/day

    b.  Calculate the  sludge loading rate.
                                   "  HPD

 where

      LR = loading rate,  Ib/hr

      SP = sludge produced,  128U  Ib/day

     HPD = work schedule, 8  hr/day

                                 TR -
                                 LR -
                              LR = 160 Ib/hr

     c.  Calculate sludge heat value.


                                  5-200

-------
                    BS =



 where


     BS = sludge heat  value,  Btu/lb


     C  = carbon in sludge,  1*3.6 percent


     H  = hydrogen in  sludge, 6.1* percent


     C^ = oxygen in sludge,  33.U percent


     S  = sulfur in sludge,  0.3 percent
              BS  =  ll*5(U3.6)  +  620   e.k  -         + 1*5(0.3)
                                                            EM 1110-2-501

                                                              Fart 1 of 3

                                                                29 Sep 78
                            BS =  7695 Btu/hr


     d.   Calculate the  sludge loading rate.


                           SL= 10(2.7-0.022M)




where


     SL = sludge loading rate, Ib/ft /hr


     M = moisture content of dewatered sludge, 60 percent


                          SL = 10[2. 7-0. 022(60)]



                            SL = 2U Ib/ft2/hr


     e.  Calculate cross-sectional area of incinerator.



                                 A = M
                                 A   SL

where

                 p
     A = area, ft



                                5-201

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EM 1110-2-501

Part 1 of 3

 29  Sep 78


    LR = loading rate, 160 Ib/hr

                                      Q
    SL = sludge loading rate, 2h Ib/ft /hr


                                 A - 16°
                                 A ~ ~2U


                               A = 6.7 ft2


    f.  Calculate diameter of incinerator.
where


    D = diameter, ft


    A = area, 6.7 ft2
                               D = 2.92 ft


    g.  Compute auxiliary fuel supply.


    (l)  Calculate burning rate.


                         BR = 10(5.9U7-0.0096M)


where

                             2
    BR = burning rate, Btu/ft /hr


     M = moisture content of dewatered sludge, 60 percent


                        BR = 10t5.9^7-0.0096(60)]



                        BR = 23^,960 Btu/ft2/hr


    (2)  Compute total heat input rate.



                                 5-202

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                                                            EM 1110-2-501
                                                              Part 1 of 3
                                                                29 Sep 78''

                                HIR = BR(A)
 where

     HIR = heat input rate,  Btu/hr

       A = area,  6.7 ft2
      BR =  burning rate,  23^,960 Btu/ft  /hr

                            HIR = 231|,960(6.T)

                          HIR = 1,57*1,250  Btu/hr

     (3)  Calculate heat  input from  sludge.

                               HIS = BS(LR)

vhere

     HIS  =  heat input, from  sludge,  Btu/hr

     BS  =  sludge  heat value,  7695 Btu/lb

     LR  =  loading rate,  l60  Ib/hr

                              HIS  =  7695(160)

                         HIS  = 1,231,200  Btu/hr

     (U)  Calculate auxiliary  fuel supply.

                             AFS  = HIR -  HIS

where

    AFS = auxiliary fuel supply, Btu/hr

    HIR = heat input rate, 1,574,250 Btu/hr

    HIS = heat input from sludge, 1,231,200 Btu/hr



                                 5-203

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EM 1110-2-501

Part 1 nf 3
29 Sep 78


                       AFS = 1,57^,250 - 1,231,200



                          AFS = 3^3.050 Btu/hr


    (5)  Calculate fuel oil required.
                                     HV

where


     FO = fuel oil required, l"b/hr


    AFS = auxiliary fuel supply, 3^3,050 Btu/hr


     HV = heat value of fuel, 18,000 Btu/lb
                                 -
                                 "  18,000


                              FO = 19 Ib/hr


    h.  Compute air supply rate (20$ excess).


     (l)  Calculate air supply rate for sludge.



               qx = 0.0127[LR(2.67C1 + 7-9^ + S^ - 0^)]


where


     q.   = air  supply for  sludge, scfm


     LR  = loading rate, 160 Ib/hr


     C   = carbon in sludge, U3.6 percent


     H   = hydrogen in  sludge, 6.k percent


     S   = sulfur in sludge, 0.3 percent


     0   = oxygen in sludge, 33.^ percent



         q  = 0.0127{l6o[(2.67)(^3.6) + 7- 9^(6. U) +  0.3  -  33-U]}



                                 5-204

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                                                           EM 1110-2-501
                                                             Part 1 of ^
                                                               29 Sep  78
                             q  = 272.5 scfm


    (2)  Calculate air supply rate for fuel.


               q2 = 0.0127[FO(2.67C2 + 7-9^ + S2 - 0^)]


where


    q  = air supply rate for fuel, scfm


    FO = fuel oil required, 19 lb/hr


    C  = carbon in fuel, 87-3 percent


    H  = hydrogen in fuel, 12.6 percent


    S  = sulfur in fuel, 1.0 percent


    0  = oxygen in fuel, 0 percent


           q2 = 0.0127[19(2.67)(87.3) + 7«9Ml2.6) + 1.0 - o)]


                             q  = 80.6 scfm


    (3)  Calculate air supply rate.




where


     q = total air supply, scfm


    q  = sludge air supply, 272.5 scfm


    q  = fuel air supply, 80.6 scfm


                            q = 272.5 + 80.6


                                q = 353.1

    i.  Calculate total gas flow.


                                 5-205

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 EM 1110-2-501
 Part 1 of 3
 29 Sep 78
                         t       100
where

    q^ = total gas flov, scfm

     q = air supply rate, 353.1 scfm

    LR = loading rate,  160 Ib/hr

     M = moisture content, 60 percent
                                          /_M_\
                                      - M \3.01/
                                  ioo - 6o

                              q, = ^33 scfm

    j.  Calculate air preheater capacity.

    (l)  Calculate the air-to-sludge ratio.
                                              60
where

    ASR = air-to-sludge ratio, Ib air/lb sludge

      q = air supply rate, 353.1 scfm

     LR = loading rate, 160 Ib/hr


                            ASR = ^-


                       ASR = 9.9 Ib air/lb sludge

    (2)  Calculate air preheater capacity.

                       APHS = 0.2MASR)(T2 - T

where


                                 5-206

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                                                          EM 1110-2-501
                                                            Part  1  of  3
                                                             29 Sep 79
    APHS = air preheater capacity, Btu/hr

     ASR = air-to-sludge ratio, 9-9 !b air/lb sludge

      T = operating temperature , 1100°F

      T = incoming air temperature, 72°F

      LR = loading rate, l60 Ib/hr


                     APHS = 0.2U(9.9)(HOO - 72)160


                         APHS =  390. SOU Btu/hr

    k. Assume  a retention time for incinerator.

                              dt = 15 sec
    1.   Determine volume  of  reactor.
where

     V = volume of reactor,  ft

    cr  = total gas flow,  U33 scfm

    dt = detention time,  15  sec

                             V  -

                             V  = 108.3  ft3

    m.  Calculate height  of  reactor.


                                 "-}
where

    H = height of reactor, ft

                                 5-207

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 EM 1110-2-501
 Part 1 of 3
 29  Sep 78

     V = volume  of reactor,  108.3  ft
                                p
     A = area  of reactor,  6.7  ft

                                     108.3
                               H = 16.2  ft


                          |= |~= 5.5  (OK)


    n.   Check heat release rate (H  _<_ 50,000 Btu/hr/ft)

                                 n  = HIR
                                  r    V
where
                                      o
     H   = heat release rate, Btu/hr/ft

    HIR  = heat input rate, 1,57^,250 Btu/hr

      V  = volume, 108.3 ft3

                             H  = 1,57^,250
                              r     108.3
                     = lH,536 Btu/hr/ft3 <_ 50,000 (OK)
    o.  Assume a sand-to-sludge ratio (Rss ) .


                            Ess = 5 Ib/lb/hr


    p.  Calculate depth of ASTM No. 8 silica sand.
(Y )A
  S
                                 12(LR)(Rss)
                             L =
where

      L = depth of sand, in.


                                 5-208

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                                                           EM 1110-2-501
                                                             Part  1  of  3
                                                               29  Sep 78
     LR = loading rate,  160 Ib/ft2/hr

    Ess = ratio, sand to sludge,  5 lb/lb/hr
                                            o
     Y  = specific weight of sand, 110 Ib/ft
      s
                                 2
      A = area of reactor, 6.7 ft
                              T  - 12(160)5
                              L " 110(6.7)
                               L = 13 in.
    q. Calculate grid jet velocity.
                          V  = 160 + 160 log L
                           cJ
where
    V. = grid jet velocity, fps
     J
     L = depth of sand, 13 in.
                         V. = 160 + 160 log (13)
                          J
                       V  = 338 fps > 300 fps (OK)

5-135.  Cost Data.  Appropriate cost data and economic evaluation may
be found in Chapter 8.

5-136.  Bibliography.

    a.  "Air Pollution Aspects of Sludge Incineration," EPA Technology
Transfer, EQA 625A-75-009, June 1975-

    b.  Alford, J. M., "Sludge Disposal Experiences at North Little
Rock, Arkansas," Journal, Water Pollution Control Federation, Vol Ul,
No. 1, pp 175-183.

    c.  Balakrishnan, S., Williamson, D., and Odey, R., "State of the
Art Review on Sludge  Incinerator Practices," FWQA. 17070 Div CA/70,
April 1970.

                                 5-209

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 EM 1110-2-501
 Part  1 of 3
 29 Sep  78


    d.   Burgess,  J.  V.,  "Comparison  of  Sludge  Incinerator Processes,"
 Process Biochemistry, Vol  3, No.  7,  1968, pp 27-30.

    e.   Cardinal, P. J., "Advances in Multihearth Incineration," Process
 Biochemistry, Vol 6, 1971, PP 27-31.

    f.   Copeland, C. G., "Design  and Operation of Fluidized Bed Inciner-
 ators," Water and Sewage Works, Vol  117, 1970, p R245-9.

    g.   Copeland, C. G., "The Copeland  Process Fluid Bed System and
 Pollution  Control Worldwide," Proceedings, 19th Industrial Waste
 Conference, Purdue University, Lafayette, Indiana, 1964.

    h.   Copeland, C. G. , "Water Reuse and Black Liquor Oxidation by the
 Container-Copeland Process," Proceedings, 19th Industrial Waste
 Conference, Purdue University, Indiana, 196k.

    i.   Fair, G. M. and Geyer, J. C.  , Elements of Water Supply and Waste
 Water Disposal, John Wiley and Sons, Inc., New York, 1955.

    j.   Fair, G. M., and Moore, E. W.,  "Sewage Sludge Fuel Value Related
 to Volatile Matter," Eng. News Record,  1935, p 68l.

    k.   Gaillard, J. R., "Fluidized Bed Incineration of Sewage Sludge,"
 Water Pollution Control, Vol 73, pp 190-192, 1973.

    1.   Hanway, J. E., "Fluidized-Bed Processes - A Solution for Indus-
 trial Waste Problems," Proceedings,'21st Industrial Waste Conference,
 Purdue  University, Lafayette, Indiana, 1966.

    m.   Harkness, N. et al, "Some Observations on the Incineration of
 Sewage  Sludge," Water Pollution Control. Vol 71,  No.  1, 1972, pp 16-33.

    n.   Liao, P. B., "Fluidized-Bed Sludge Incinerator Design," Journal,
Water Pollution Control Federation,  Vol 1*6,  No. 8, 1974, pp 1895-1913.

    o.   Liao, P. B.  and Pilat,  M.  J., "Air Pollutant  Emissions from
Fluidized Bed Sewage Sludge Incinerators," Water  and Sewage Works
Vol 119, No.  2, pp 68-72.

    p.   Liptak, B. G.,  Environmental  Engineers Handbook, Vol 1, Chilton
Book Company, Radnor, Pennsylvania,  1974.
                                5-210

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78

    q..  Lor an, B. I. , "Burn That Sludge," Water and Wastes Engineering,
Vol 12, No. 10, 1975, PP 65-68.

    r.  Millward, R. S. and Booth, P. B. , "Incorporating Sludge Com-
bustion Into Sewage Treatment Plant," Water and Sewage Works, Vol 115,
No. R-169-171*, 1968.

    s.  Pavoni, J. L. et al, Handbook of Solid Waste Disposal, Van
Nostrand Reinhold Company, Nev York, 1975-

    t.  "Process Design Manual for Sludge Treatment and Disposal," EPA
Technology Transfer, EPA 625/11-7^-006, October 197^.

    u.  "Sludge Incineration Plant Uses Fluid-Bed Furnace,"  Chemical
and Process Engineering, April 1972, p 7.

    v.  Vesilind, P. A. , Treatment and Disposal of Waste-water Sludges,
Ann Arbor Science, Ann Arbor, Mich.,
                                 5-211

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EM 1110-2-501
Part 1 of  3
29 Sep 78
           Table 5-33.  Normal Quantities of  Sludge Produced  by
                       Different Treatment Processes



Wastewater Treatment Process
Primary sedimentation
Undigested
Digested in separate tanks
Trickling filter
Chemical precipitation
Primary sedimentation and
activated sludge
Undigested
Digested in separate tanks
Activated sludge
Waste sludge
Septic tanks, digested
Imhoff tanks , digested
Gallons
Sludge/
mg
Treated

2,950
1,1*50
7^5
5,120


6,900
2,700

19,^00
900
500


Solids
percent

5-0
6.0
7-5
7-5


h.O
6.0

1.5
10.0
15-0

Sludge
Specific
Gravity

1.02
1.03
1.025
1.03


1.02
1.03

1.005
I. Oh
l.Oh
            Table  5-3^.   Process Efficiencies for Dewatering
                           of Wastewater Sludge
Unit Process
Centrifugation
Solid bowl
Disc-nozzle
Basket
Dissolved air flotation
Drying beds
Filter press
Gravity thickener
Vacuum filter
Solids Capture, percent
80-90
80-97
70-90
95
85-99
99
90-95
90+
Cake Solids , percent
5-13
5-7
9-10
h-6
8-25
1|0-60
5-12
28-35
                               From EPA Process Design Manual for Sludge Treatment and Disposal
                                  5-212

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                                                          EM  1110-2-501
                                                            Part  1  of  3
                                                               29  Sep 78
        Table 5-35.   Recommended Fluidized Bed Sludge Incinerator
                             Design Criteria
                Parameter
Sludge loading rate*
Burning rate
Heat release rate
Air:dry sludge ratio
Fuel:dry sludge ratio*
Combustion temperature
Retention time (at standard conditions)
Pressure drop
Height:diameter ratio
Grid jet velocity
Freeboard gas velocity
Stack gas velocity
Ratio of freeboard diameter:grid diameter
Ratio of No. 8 sand to sludge rate**
         Magnitude
5 to UO Ib dry sludge/hr/ft'
Up to 300,000 Btu/hr/ft2
Up to 50,000 Btu/hr/ft3
6 to 50 Ib/lb
0 to 30,000 Btu/lb
1200 to lli000F
10 <_ time <_ 50 sec
50 to 100 in. of water
k to 6:1
Greater than 300 fps
5 to 10 fps
20 to 50 fps
1.5
3 to 8 Ib/hr/lb
 *  Sludge loading rates and air and fuel requirements depend on sludge
   moisture content and the ratio of air and sludge.
**  Sand to sludge ratios depend on sludge moisture content.
                                5-213

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                                                          EM 1110-2-501
                                                            Part 1 of 3
                                                              29 Sep 78

                                CHAPTER 6

                         CHEMICAL UNIT PROCESSES

                        Section I.  INTRODUCTION

6-1.  Definition.   Chemical processes may involve the addition of chemi-
cals, the use of chemical reaction columns,  and the use of electrical
currents.  In the process design procedure,  although the fundamentals of
chemistry are not discussed, a basic knowledge cf chemistry is helpful
when assessing the applicability of such processes to a particular waste
treatment problem.  The processes included in this section are:

    a.  Carbon adsorption.

    b.  Chemical coagulation.

    c.  Ammonia stripping.

    d.  Chlorination.

    e.  Ion exchange.

    f.  Neutralization.

    g.  Recarbonation.

    h.  Two-stage lime treatment.
                                                      (next  page  is  6-3)

-------
                                                          EM 1110-2-501
                                                            Part 1 of 3
                                                               29 Sep 78

                     Section II.   CABBON ADSORPTION

6-2.   Background.

    a.  Adsorption is the process by which matter is  extracted  in a
first phase and concentrated at the surface in a second phase.   Adsorp-
tion with activated carbon has long been used to remove taste and odor-
causing impurities from public water supplies.  However, with the advent
of physicochemical systems, carbon adsorption has emerged as a  practical,
reliable, and economically competitive process in wastewater treatment.

    b.  The most efficient and practical use of activated carbon in
wajtewater treatment has been in fixed beds of granular carbon  in com-
bination with chemical coagulation and precipitation  for the removal  of
suspended impurities.  In such systems, the wastewater is applied to  the
bed at a rate ranging from U to 8 gpm/ft2.  Contact  times employed  range
from  30 to 60 min.  Provision must be made to regularly backwash packed
bed carbon systems to flush out accumulated suspended solids and biolog-
ical  growth.  A good design practice is to allow for  a bed expansion  of
from  10 to 15 percent.  Flow rates during backwashing may range from
10 to 15 gpm/ft2.  Biological growth can be controlled effectively  by
chlorination of influent to the columns or by chlorination during the
regular backwash operation.  Figure 6-1 shows a typical activated-carbon
adsorption column.

    c.  Packed beds of granular carbon are suitable  only for wastewaters
containing low suspended solids.  However, biological growth and an
accumulation of solids present in the waste have often presented prob-
lems  in the use of packed bed adsorbers.  To eliminate these problems,
expanded bed adsorbers have been recommended.  This  system passes  the
waste upward through the bed at velocities sufficient to expand the bed
about 10 percent.  Expanded beds require little or no cleaning or back-
washing and have low and constant feed pressure requirements.
     d.  The adsorption capacity of the activated carbon can be measured,
 to  a fair degree, by conducting isotherm studies in the laboratory.
 Design  data, however, must be evaluated from pilot plant carbon column
 tests.  These data will include the minimum contact time required to
 produce the desired effluent quality, optimum flow rates, head loss at
 various flows, backwash rate, and required carbon dosage.  The effluent
 resulting from physicochemical treatment systems has been reported to


                                  6-3

-------
 EM 1110-2-501
 Part 1 of 3
 29 Sep 78
                                         /• FULL OPEN COVER WITH
                                        /  15-IN. PORTHOLE
                (20) 1-IN. HOLES
                                             k-^-eOLT- RING
                                                CHARGE

                                           — CARBON BED SURFACE
                   16 FT
                                            	^_ CARBON
                                                DISCHARGE
                                            EFFLUENT
                                            BACKWASH
                                             Me teal f and Eddy, 1972
                   Figure 6-1.  Typical  activated-car"bon
                             adsorption  column.

be crystal  clear  and suitable for many  reuse  aDplications.  Carbon  ad-
sorption should be considered in the design of  physicochemical  systems,

6-3.  Input Data.

    a.  Wastewater flow, mgd.

    (l)  Average daily  flow,  mgd.

    (2)  Flow variations, mgd.

    b.  Wastewater characteristics.

    (1)  BOD, mg/£.

    (2)  Chemical  oxygen demand (COD), mg/£.

    (3)  Suspended solids,  mg/£.
                                  6-k

-------
                                                           EM 1110-2-501
                                                             Part  1 of 3
                                                              29 Sep"78
    (10   PH.

    (5)   Total organic carton (TOG),  mg/Jl.


6-H.   Design Parameters.

    a.  Carbon requirements,  rb/million gal (from pilot plant).


    (l)   Tertiary treatment (^50-350 Ib/million gal).


    (2)   Secondary treatment  (^00-1800 It/million gal).

                                     o
    TD.  Hydraulic loading (U-8 gpm/ft ).


    c.  Contact time (30-60 min).

                                   2
    d.  Backwash rate (10-15 gpm/ft ).


    e.  Breakpoint concentration.


    f.  Backwash time, min.

    g.  Adsorption capacity, Ib/ft  (from laboratory study).


    h.  Rate constant, ft /rb carbon/hr (from laboratory study).


6-5.  Design Procedure.

    a.  Select a minimum contact time and calculate bed volume.
where

    Vol = volume of bed, ft

    MCT = minimum contact time, min

     Q  = peak waste flow, mgd


    b.  Select a minimum flow rate and calculate surface area.
                                  6-5

-------
 EM 1110-2-501
 Part  1 of 3
 29 Sep 78
                          SA =
where
                         2
     SA =  surface  area, ft

     Q  =  peak waste flow, mgd

     FR =  flow rate, gpm/ft2

     c.  Calculate column depth.
where

     CD = column depth, ft
                           -3
    Vol = volume of bed, ft
                          2
     SA = surface area, ft

    d.  Calculate total service time.
     ST =	—r	
          (0.621; x 10  )(60)C (FR)
(CD>  - —15?— *  c:
                                                 o
where

          ST = total service time to breakthrough, hr

          NQ = equilibrium adsorption capacity of carbon, lb
               TOC/ft3_carbon (from pilot plant)

          C  = initial concentration, mg/£

          FR = flow rate, gpm/ft2
                                 6-6

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                              29 Sep 78
              CD = column depth,  ft
               K = rate constant,  ft /lb carbon/hr  (from laboratory or
                   pilot plant)

              In = natural log

              C_ = concentration at break point,  mg/£
               o
    0.62U x io~  = conversion factor, mg/£ to Ib/ft

    e.  Calculate total volume of waste treated before exhaustion.


                         TVWT = (ST)(Q   )
                                      avg

where

    TVWT = total volume waste treated prior to exhaustion,  million  gal

      ST = total service time, hr

    Q    = average waste flow, mgd

    f.  Calculate frequency of column regeneration  per month.
                                       (30) (106)
where

    NCRM = frequency of column regeneration/month

    Q    = average waste flow, mgd

    TVWT = total volume of waste treated per one regeneration

    g. ' Calculate bed efficiency.

                          (TVWT)(C  - c
                                                <100)
                                  6-7

-------
EM 1110-2-501
Part 1 of 3

29 Sep 78


where


     eff = bed efficiency, percent


    TWT = total volume of vaste treated, million gal


      C  = initial concentration, mg/£


      CL = breakpoint concentration, mg/£

                                                     •3
      N  = equilibrium adsorption capacity, Ib TOC/ft

                            3
     Vol = volume of bed, ft


    h.   Select a flow rate for backwashing and calculate water
requirement.



                            WRBW = (RFR)(SA)



where


    WRBW = water requirements for backwashing, gpm

                                        2
     RFR = backwashing flow rate, gpm/ft

                                  2
      SA = surface area of bed, ft


    i.   Select total time for backwashing and calculate total volume of
"backwash water.



                           VBWW = (WRBW)(BWT)



where


    VBWW = total volume of backwash water, gal


    WRBW = backwash water requirement, gpm
                                                                  *

     BWT = total backwash time, min
                                  6-8

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
 6-6.  Output Data.

    a.   Carbon requirements, lb/million gal.

    b.   Minimum contact time, min.
                         2
    c.   Flow rate, gpm/ft .
                             2
    d.   Backwash rate, gpm/ft .

    e.   Backwash time, min.
                      9
    f.   Bed volume, ft .
                        2
    g.   Surface area, ft .

    h.   Column depth, ft.

    i.   Service time prior to regeneration, hr.

    j.   Volume treated prior to regeneration, gal.

    k.   Frequency of regeneration/month.
    1.   Bed efficiency, percent.

    m.   Volume of backwash water, gal.

 6-1.  Example Calculations.

    a.   Select a minimum contact  time and calculate bed volume.
where
    Vol = volume of bed, ft
    MCT = minimum contact time, ^5 min
     Q  = peak wastewater flow, 2 mgd


                                 6-9

-------
EM 1110-2-501
Part 1 of 3
29 Sep 7&
                      Vol = 83^6 ft3

    b.  Select a minim-urn flow rate and calculate surface area.
                          SA = \FR
where
                         2
    SA =  surface area, ft
    Q  = peak wastewater flow, 2.0 mgd

    FR = flow rate, U.O gpm/ft2
                             _  /2.0\ (106
                          SA = 3^7 ft2
     c.  Calculate column depth.
where
     CD = column depth, ft

    Vol = volume of column, 8356 ft
                              o
     SA = surface area, 3^7 ft



                                 6-10

-------
                                CD = 2k ft
    d.  Calculate total  service time.
                                                          EM 1110-2-501
                                                            Part 1 of 3

                                                             29 Sep  78
     ST =
                              )(FR)
                                 <•»-
                                           (FR)
where
          ST = total service  time to breakthrough, hr

          N  = equilibrium  adsorption capacity of carbon,
           °   TOC/ft3

          C  = initial  concentration, 100 mg/£

          FR = flow rate, U.O gpm/ft2

          CD = column depth,  2h ft

           K = rate constant, 11.0

          C_ = concentration  at breakpoint, 20 mg/£

0.62*1 x io~  = conversion factor, mg/£ to lb/ft3
                                                                 Ib
     ST =
                 (U.UH7.U8)
                                                      In
     ST =  507 hr
    e.   Calculate total volume of waste treated before  exhaustion.
                                6-11

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78
                          TVWT =
where

    TWT = total volume of waste treated before exhaustion,  million gal

      ST = total service time to breakthrough,  507 hr

    Q    = average flow, 1.0 mgd



                        TVWT = 507(1.0)



                        TVWT = 21.125 million gal


    f.  Calculate frequency of column regeneration per month.

                                   Q
                            NCRM = T~£ (30)
where

    NCRM = number of column regenerations per month

    Q    = average flow, 1.0 mgd

    TVWT = total volume of waste treated before exhaustion, 21.125 mil-
           lion gal


                     NCRM = 2I7I25 (30)


                     NCRM = 1.U2 regenerations/month


    g.  Calculate bed  efficiency.


                            TVWT(C  -  C  )(8.3U)
                       eff = 	o    *>	 10Q
                                  N (Vol)
                                   o


                                  6-12

-------
                                                            EM 1110-2-501
                                                              Part 1 of 3
                                                               29 Sep  78
 where


      eff = bed efficiency, percent


     TVWT = total volume of waste treated, 21.125 million gal


       CQ = initial concentration, 100 mg/£


       CB = breakpoint concentration, 20 mg/£


       NQ = equilibrium adsorption capacity,  h.k Ib TOG /ft3

      Vol = volume of bed,  8356 ft3
                     eff =
                       1
                     eff = 38 percent



     h.   Select a flow rate for backwashing  and  calculate water
 requirement.



                              WRBW = RFR(SA)


 where


    WRBW = water requirements  for backwashing, gpm


     RFR = backwashing  flow rate, 15 gpm/ft2

                                r)
      SA = surface area,  3^7  ft


                             WRBW = 15(31*7)


                             WRBW = 5205 gpm



    i.   Select total time for backwashing and calculate total volume of
backwash water.
                                 6-13

-------
 EM 1110-2-501
 Part 1 of 3
29 Sep 78

                            VBWW = WRBW(BWT)

 where

     VBWW =  total volume of backwash water, gal

     WRBW =  "backwash water requirement,  5205 gpm

     BWT =  total backwash time, 15 min


                            VBWW = 5,205(15)

                            VBWW = 78,075  gal

 6-8.   Cost  Data.   Appropriate  cost data and economic  evaluation may be
 found  in Chapter 8.

 6-9-   Bibliography.

     a.   Cover,  A.  E.  and Pieron, L. J.,  "Appraisal  of Granular Carbon
 Contactors  Phase I and II," Report No.  TWRC-11, May 1969,  Federal  Water
 Pollution Control  Administration, Washington, D.  C.

     b.   Cover,  A.  E.  and Wood, C. E.,  "Appraisal  of Granular  Carbon  Con-
 tactors Phase III," Report No. TWRC-12,  May 1969, Federal  Water Pollu-
 tion Control Administration, Washington, D. C.

     c.   Gulp, R. L. and Gulp,  G. L.,  Advanced Wastewater Treatment,  Van
 Nostrand, New York, 19T1-

     d.   Eckenfelder,  W. W., Jr., Industrial Water Pollution Control,
 McGraw-Hill, New York, 1966.

     e.   Metcalf and E.d.dy,  Inc., Waabewater Engineering;  Collection,
 Treatment,  and Disposal, McGraw-Hill,  New  York,  1972.

     f.   Mine Safety Appliances Research Corporation,  "Optimization of
 the Regeneration Procedure for Granular Activated Carbon," Report
 No. 1T020DAO, Jul  19TO, U. S.  Environmental Protection Agency, Washing-
 ton, D. C.
                                   6-11*

-------
                                                            EM 1110-2-501
                                                              Part  1  of 3
                                                                29  Sep 78
    g.  South Tahoe Public Utility District, "Advanced Wastewater
Treatment as Practiced at South Tahoe," Report Ho. 17010ELQ, Aug 1971
U. S. Environmental Protection Agency, Washington, D. C.              '

    h.  Swindell-Dresser Company, "Process Design Manual for Carbon
Adsorption," Oct 1971, U. S. Environmental Technology Transfer  Washing-
ton, D. C.

(i       U. S. Environmental Protection Agency, Technology Transfer,
 Process Design Manual for Upgrading Existing Wastewater Treatment
Plants," 1973, Washington, D. C.

    J.  Weber, W. J., Jr., "Principles and Applications of Adsorption,"
Manual of Treatment Processes. Environmental Science Services  Inc
Briarcliff Manor, New York, 1969.                            '     ''

    k.  Weber, W. J., Jr., Physicochemical Processes for Water  Quality
Control, Wiley-Interscience,  New York,  1972.              ~	
                                                   (next page is 6-17)

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                                                           EM 1110-2-501
                                                             Part 1 of  3
                                                              29 Sep  78
                    Section  III.   CHEMICAL  COAGULATION
 6-10.   Background.
     a.   Chemical  coagulation  involves the aggregation of small particles
 into large, more  readily  settleable conglomerates.  Chemical coagulation
 is  a common process used  in water treatment for the removal of turbidity
 and color.  In wastewater treatment, chemical coagulation has been used
 to  remove colloidal and suspended matter from raw wastes, remove phos-
 phorus,  remove algae from oxidation pond effluents, and enhance sludge
 dewaterability.

     b.   Wastewater can be coagulated using any of the coagulants common
 for water treatment.  The most widely used chemicals include:  iron
 salts  (ferric chloride, ferric sulfate, ferrous chloride, and ferrous
 sulfate), aluminum salts  (alum and sodium aluminate), lime, and syn-
 thetic polymers.  The choice  of chemicals should be based on careful
 evaluation of the wastewater  characteristics, availability and cost of
 the coagulant, and sludge handling and disposal characteristics.   Jar
 tests must be conducted to determine the coagulant dosage, the optimum
 conditions for coagulation, the quality of the effluent, and the charac-
 teristics of the chemical sludge.

     c.   Chemical coagulation  systems normally consist of rapid mix
 basins for dispersion of the  coagulants, flocculation basins where the
 coagulated solids agglomerate to form settleable solids, and settling
 basins to separate the floe from the liquid.   Rapid mix basins are
 equipped with high-speed mixing devices designed to create velocity
 gradients of 300 fps/ft or more with a detention time of 15-60 sec.
 Power requirements for mechanical mixers range from 0.25 to 1 hp/mgd.

     d.  Flocculation may be accomplished in a separate basin or in an
 integral part of the clarifier structure.   The velocity in the conduits
 conveying the floe to the clarifier should be 0.5-1.0 fps to prevent
 shearing of the floe.   Velocity gradients  ranging from 30 to 100  fps/ft
may be induced by mechanical means (usually revolving paddles),  or by
 air diffusion.  Flocculator detention times  of 15-60 min have commonly
been used in water treatment plant design.

    e.  Clarifiers for the separation of the  chemical floe  are usually
designed on the basis  of hydraulic loadings  (chap 5,  sec VIII).   Typical
hydraulic loadings for clarifiers (sedimentation basins) processing
various types of chemical sludges are  presented in Table 6-1.   Detention
times ranging from 2 to 6 hr have been used  (Table 6-2).


                                 6-17

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78

    f.  Chemical coagulation may be used as a part of a physicochemical
treatment system or for phosphorus removal from wastewaters generated at
recreation areas.

6-11.  Input Data.

    a.  Wastewater flow, mgd.

    (l)  Average daily flow, mgd.

    (2)  Variation in flow, mgd.

    b.  Wastewater characteristics.

    (l)  BOD, total and soluble, mg/£.

    (2)  COD, total and soluble, mg/£.

    (3)  Phosphorus, mg/£.

    (U)  Suspended solids, mg/£.

    (5)  pE.

    (6)  Alkalinity, mg/£.

6-12.  Design Parameters.

    a.  Desired  quality of treated effluent, mg/£.

    b.  Coagulant dosage, mg/£  (jar test).

    c.  Detention time of rapid mix basin  (l-3 min).

    d.  Detention time of flocculator basin  (15-60 min).

6-13.  Design Procedure.

    a.   Calculate coagulant  requirements.


                          CR =  (CD)(Q
                                  6-18

-------
                                                            EM 1110-2-501
                                                              Part 1 of 3

                                                               29  Sep 78
 vhere


       CR = coagulant requirements,  Ib/day

       CD = coagulant dosage,  mg/&

     Q    = average daily flow,  mgd


     b.   Calculate volume of flash mixing  basin.


                     VFM = (Qp)(DTFM)(l06)


 where


      VFM = volume of flash  mix  basin, gal

      Q   = peak flow, mgd


     DTFM = detention time of  flash mixer, min (l-3 min)

     c.   Calculate  volume  of flocculator basin.


                     VFL= (Qp)(DTFL)(l06)  fa) fa)


where


     VFL = volume  of flocculator basin,  gal

      Q  = peak flow, mgd


    DTFL = detention time of flocculator basin,  min (15-60 min)

    d.  Design clarifier as presented under the  design of primary
sedimentation.

6-lU.  Output Data.

    a.  Coagulation process.

    (l)   Coagulant dosage, mg/£.

    (2)   Optimum pH.


                                  6-19

-------
EM 1110-2-501

Part 1 of 3

29 Sep 78



    (3)  Rapid mix detention time, min.



    (U)  Flocculator detention time, min.



    (5)  Coagulant requirement, rb/day.



    (6)  Volume of flash mix "basin, gal.



    (7)  Volume of flocculator basin, gal.



    "b.  Clarifier.



    (l)  Overflow rate, gal/day/ft  .


                         p

    (2)  Surface area, ft .



    (3)  Side water depth, ft.



    (h)  Detention time, hr.



    (5)  Solid loading, Ib/ft2/day.



    (6)  Weir loading, gal/ft/day.



    (7)  Weir length, ft.



    (8)  Volume of sludge produced, gal/day.



    (9)  Suspended solids removal,  percent.



    (10)  BOD removal, percent.



    (ll)  COD removal, percent.



    (12)  Total Kjeldahl nitrogen  (TKN)  removal, percent,



    (13)  P0< removal, percent.



6-15.  Example Calculations.



    a.   Calculate coagulant requirements.





                            CR =  CD(Q    )8.3^
                                     avg





                                   6-20

-------
                                                            EM 1110-2-501
                                                              Part  1 of 3
                                                               29 Sep 78
 where

       CR = coagulant requirements,  Ib/day

       CD = coagulant dosage,  20 mg/£

     Q    = average flow,  1.0  mgd
      o» v^

                            CR  =  20(1.0)8.3^

                            CR  =  166.8 Ib/day


     b.   Calculate  volume  of flash mixing  basin.


                                  Q  (DTFM)IO

                           VFM  =    60(2*0

 where

     VFM = volume  of flash mix  basin, gal

      Q  = peak flow, 2.0 mgd

    DTFM = detention time flash mixer, 1 min
                                    (60) 2k


                            VFM = 1389 gal


    c.  Calculate volume of flocculator basin.


                                  Q (DTFL)lO

                            VFL =   60(2*0
where

     VFL = volume of flocculator basin, gal


                                 6-21

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78

      Q  = peak flow, 2.0 mgd

    DTFL = detention time flocculator, 30 min
                                - 2.0(30)106
                                *
                            VFL = Hi,667 gal
    d.  Design clarifier as presented under the design of primary
sedimentation.

6-1.6.  Cost Data.  Appropriate cost data and economic evaluation may be
found in Chapter 8.

6-17•  Bibliography.

    a.  American Water Works Association, Water Quality and Treatment,
McGraw-Hill, New York, 1971.

    b.  Camp, T. R., "Flocculation and Flocculation Basins," Transac-
tions, American Society of Civil Engineers, Vol 120, 1955, PP 1-16.

     c.  Cohen, J. M. and Hannah, S. A., "Coagulation and Flocculation,"
Water Quality and Treatment, McGraw-Hill, New York, 1971.

     d.  Gulp, R. L. and Gulp, G. L., Advanced Wastewater Treatment,
Van  Nostrand, New York, 1971.

     e.  Eckenfelder, W. W., Jr., and Cecil, L. K., Application of  New
Concepts of Physical-Chemical Wastewater Treatment, Pergamon Press,
New  York,  1972.

     f.  Metcalf and Eddy,  Inc., Wastewater Engineering; Collection,
Treatment, and Disposal, McGraw-Hill, New York, 1972.

     g.  O'Melia, C. R., "Coagulation in Water and Wastewater Treat-
ment," Advances  in Water Quality Improvements—Physical and Chemical
Processes, E. F. Gloyna and W. W.  Eckenfelder, Jr., ed., University of
Texas Press, Austin, 1970.
                                   6-22

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                              29 Sep 78

    h.  Sawyer, C. N. and McCarty, P.  L.,  Chemistry for Sanitary Engi-
neers, McGraw-Hill, New York, 1967.

    i.  Stumm, W. and Morgan, J.  J., Aguatic Chemistry, Wiley, New York,
1970.

    j.  Stumm, W. and O'Melia, C. R.,  "Stoichiometry of Coagulation,"
Journal, American Water Works Association, Vol 60,  1968, pp 51^-539.

    k.  Weber, W. J., Jr., Physiochemical  Processes for Water Quality
Control, Wiley-Interscience, New York, 1972.
                                6-23

-------
EM 1110-2-501
Part 1 of  3
29 Sep 78'
              Table 6-1.  Recommended Surface-Loading Rates
                          for Various  Suspensions
     Suspension
                                              Loading Rate, gpd/ft?
Untreated wastewater

         (a)
   Range
Alum floe

Iron floe

Lime floe
         (a)
600 to 1200

360 to 600

    to 800

    to 1200
Peak Flow

  1200

   600

   800

  1200
/ x                                                      From Gulp and Gulp, 1971
     Mixed with the settleable  suspended solids  in the untreated waste-
    water and colloidal or  other  suspended solids swept out by the floe.
         Table 6-2.  Detention Times  for  Various  Surface-Loading
                          Rates  and Tank  Depths
Surface-Loading
Rate, gpd/ft2
Uoo
600
800
1000

7- ft
Depth
3.2
2.1
1.6
1.25
Detention
8- ft
Depth
3.6
2.U
1.8
I.k
Time , hr
10- ft
Depth
3.0
2.25
1.8

12- ft
Depth
3.6
2.7
2.2
                                                        From Gulp and Gulp, 1971

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                                                           EM  1110-2-501
                                                            Part  1  of  3
                                                             29 Sep 78

                     Section IV.   AMMONIA STRIPPING

6-l8.  Background.

    a.  The process of ammonia stripping converts ammonium ions in the
waste to ammonia gas and then strips off the ammonia gas by agitating
the waste in ammonia-free air.  Ammonium ions in wastewater exist  in
equilibrium with ammonia and hydrogen ions as follows:


                             NH^ j NH  + H+


As shown in the equation above, raising the wastewater  pH above 7  will
shift the equilibrium to the right, thus ammonia gas is formed. Raising
the pH beyond 11 will, therefore, convert most of the ammonium ions  to
ammonia gas which can be liberated by agitation of the  wastewater  in a
stripping tower equipped with an air blower.

    b.  Ammonia stripping towers may be operated as crosscurrent or
countercurrent flow; most designers now seem to prefer  the crosscurrent
design.

    c.  Limitations of ammonia stripping towers were first revealed
during the initial operation of the Lake Tahoe project, conducted  during
the winter season.  Some of these limitations are:

     (l)  The towers are inoperable at air temperature below 0°C due  to
the freezing of water at the air inlet.

     (2)  Since ammonia solubility increases with decreasing temper-
atures, more air is required to remove it (800 ft^/gal  at 0°C), result-
ing  in increased cost of treatment.

     (3)  A mostly calcium carbonate scale forms in the  tower.

    d.  Typical design parameters for various ammonia levels of removals
obtained during the Lake Tahoe tests are summarized in  Table 6-3.

     e.  Figure 6-2 is a typical flow sheet for ammonia  stripping of
raw wastewater.  Figure 6-3 is a typical flow sheet for the stripping  of
ammonia from digester supernatant.
                                6-25

-------
EM 1110-2-501
Part 1 of 3
 29 Sep 78
                                  AIR, NH
                                                           SETTLING
                                                            TANK
                                                                    TREATED
                                                                   EFFLUENT
               Figure 6-2.   Typical flow sheet for ammonia
                      stripping of raw wastewater.
   DIGESTER
  SUPERNATANT
                                             AIR. NH
                                          STRIPPER
                             SLUDGE
                                                        SCRUBBER
                                     CO
                                                               ^_ ACID
                                                                (NH3)
                                                    (RECARBONATION OPTIONAL)
          Figure 6-3-  Typical flow sheet for the stripping  of
                   ammonia from  digester supernatant.
                                  6-26

-------
                                                           EM 1110-2-501
                                                             Part  1 of 3
                                                              29 Sep  78


6-19.  Input Data.


    a.  Wastewater flow.


    (l)  Average flow, mgd.


    (2)  Peak flow, mgd.


    b.  Wastewater characteristics.


    (l)  Ammonia concentration,  mg/£.


    (2)  pH.


    (3)  Temperature, °F.


    (U)  Air temperature,  °F.


6-20.  Design Parameters.


    a.  Desired effluent quality, mg/£.


    b.  Liquid loading rate, Ib water/hr/ft  (500-1000).

                                      p
    c.  Gas loading rate,  Ib air/hr/ft .


    d.  Packing characteristics (from manufacturer).


    e.  Lime dose to pH 11-12, mg/£.


    f.  Height of transfer unit, ft (from manufacturer).


    g.  Ammonia concentration in liquid at bottom of tower, mg/fc.


    h.  Ammonia concentration in air at bottom of tower,  mg/fc.


6-21.  Design Procedure.


    a.  Select a liquid loading rate and calculate the surface area.



                               (Q )(8.3M(106)
                          SA = -2	
                                  (LLR)(2lO



                                 6-27

-------
EM 1110-2-501
Part 1 of 3
 29 Sep 78
where
                          2
     SA = surface area, ft
     Q  = peak flov, mgd
    LLR = liquid loading rate,  I"b/ft2/hr
    "b.  Calculate gas loading rate.

                           GLR =  (2  -  IO(LLR)

where
                                    o
    GLR = gas loading rate,  lb air/ft  /hr
    LLR = liquid loading rate,  Ib/ft2/hr
    c.  Calculate tower height.
    (l)  Four countercurrent towers.
z =
                     (ATT)
where
      z = tower height,  ft
                        (A - l! Xl + X2 - O ^
                        (A - 1} X2 + X2 - (L!)
    HTU = height  of transfer unit, ft  (from manufacturer)
      A =
        _ (m)  (GLR)/29
            (LLR)/l8
                 0.026l2T
      m = O.lllTe '        (Henry's law constant)
      T = temperature,  °F
                                6-28

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3

                                                               29 Sep 78
                                     2
    GLR = gas loading rate, Ib air/ft /hr

                                    2
    LLE = liquid loading rate, Ib/ft /hr


     X  = ammonia concentration in waste at top of tower, mg/£


     X  = ammonia concentration in waste at bottom of tower,  mg/&


     Y  = ammonia concentration in air at bottom of tower, mg/£, *


     Yp = ammonia concentration in air at top of tower, mg/£


    (2)  For crosscurrent''towers.
                        Y _ Y  -m(GLR/LLR)(z/HTU)
                        A — A . e
                             i


where


      X = ammonia concentration in waste at  z  ft down the tower, mg/&


     X.  = initial ammonia concentration at top of tower, mg/£

                                     2
    GLR = gas loading rate, Ib air/ft /hr

                                    2
    LLR = liquid loading rate,  Ib/ft /hr


      z = tower height, ft


    HTU = height of transfer unit, ft (from manufacturer)


    d.  Calculate lime required to raise pH to 11:



                          LR = (Qavg)(LD)(8.3U)



where


      LR = lime requirement, Ib/day


    Q    = average flow, mgd
     avg

      LD = lime dosage, mg/£



                                  6-29

-------
 EM 1110-2-501

 Part 1  of  3

  29 Sep 78

 6-22.   Output  Data.

                                  2
    a.   Liquid loading rate, Ib/ft /hr.

                               2
    b.   Gas loading rate, Ib/ft /hr.

                              2
    c.   Tower  surface area, ft .


    d.   Tower  height, ft.


    e.   Effluent ammonia concentration, mg/£.


    f.   Wastewater flow, mgd.


    g.   Initial ammonia concentration, mg/£.


    h.   Lime requirements, Ib/day.


 6-23.  Example Calculations.


    a.   Select a liquid loading rate and calculate the surface area.




                                 Q(8.3>0106
                            an = — E _
                             A     LLR(2H)


where

                         o
    SA = surface area, ft


     Q  = peak flow,  2.0 mgd


    LLR = liquid loading rate, 600 Ib/ft2/hr




                           SA  -  2-0(8. 3M106
                            A     600(210



                           SA =  1158 ft



    b.   Calculate gas  loading rate.
                                 6-30


-------
                                                           EM 1110-2-501

                                                             Part 1 of 3



                                                               29 Sep  78


                              GLR = 3(LLR)
where
                                     2
    GLR = gas loading rate, Xb air/ft /hr

                                        2
    LLR = liquid loading rate, 600 It/ft /hr
                        GLR = 3(600)
                        GLR = 1600 Ib air/ft2/hr
    c.  Calculate tower height.  Use crosscurrent tower.




                            v  -m(GLR/LLR)(z/HTU)
                        X = A. e
                             i
where
      X = ammonia concentration in waste at  z  ft down the tower

          2.0 mg/£



     X. = initial ammonia concentration at top of tower, 30 mg/£


                           0 026l2T
      m = constant, O.lllTe '        where  T = temperature 85°F,

          m = 1.02866


                                          2

    GLR = gas loading rate, 1800 Xb air/ft /hr



    LLR = liquid loading rate, 600 Ib/ft /hr



      z = tower height, ft



    HTU = height of transfer unit, IT ft
                  2 o = 30 0e-(1-02866)(i8oo/6oo)(z/iT)
                    z = 15 ft
                                 6-31

-------
 EM 1110-2-501
 Part 1 of 3
 29  Sep  78

     d.  Calculate lime required to raise pH to 11.


                             LR = Q^ (LD)8.3^

 where

       LR =  lime required,  Ib/day

     QQirn. =  average flov, 1.0 mgd
      d Vg

       LD =  lime dosage (from laboratory  experiments),  20 mg/£


                             LR = 1.0(20)8.3k

                             LR = 167  Ib/day


 6-2U.  Cost Data.   Appropriate cost data and  economic  evaluation may be
 found in Chapter 8.

 6-25.  Bibliography.

     a.   Gulp, R.  L. and Gulp,  G.  L.,  Advanced Wastevater Treatment.
 Van  Nostrand, New York, 1971.         "                        ~"

     b.   Roesler,  J. F., Smith,  R., and Eilers, R. G. ,  "Mathematical
 Simulation of Ammonia  Stripping Towers for Wastewater  Treatment,"
 Internal Report,  Jan 1970, Advanced Waste Treatment Research Laboratory,
 Cincinnati, Ohio.

     c.   Slechta,  A. F. and Gulp,  G. L.,  "Water Reclamation Studies at
 the  South Tahoe Public Utility  District," Journal, Water Pollution
 Control  Federation, Vol 39, May 1967, pp 787-8lk.

     d.   Smith, R.,  "Design of Ammonia Stripping Towers for Wastewater
 Treatment," Seminar on Process Design for Water Quality Control,
 9-13 Nov 1970, Vanderbilt University, Nashville, Tenn.

     e.   Snow,  R. H. and Wenk, W. J. , "Ammonia Stripping Mathematical
Model for Wastewater Treatment," Report No. IITRI-C6l52-6,  Dec 1968,
Federal Water  Pollution Control Administration, Washington, D.  C.
                                  6-32

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                                                           EM 1110-2-501
                                                             Part 1 of  3
                                                               29 Sep 78
          Table 6-3.  Air and Surface-Loading Requirements  for
            20- and 2U-Ft Towers for Various Ammonia Removal
                                 20-ft Depth
                                          Surface
                                          Loading
Percent Ammonia - N Removal  ft  air/gal  gpm/ft2

            80                   230         3.6

            85                   2^0         3.2

            90                   280         2.5

            95
    2^-ft Depth
             Surface
             Loading
ft3 air/gal  gpm/ft2
    200

    210

    250

    Uoo

    800
3.9

3.55

3.0

2.0

0.8
                                                        From Gulp and Gulp, 1971
                                  6-33
 (next page is 6-35)

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                                                           EM 1110-2-501
                                                             Part  1  of  3

                                                              29 Sep 78

                        Section V.   CHLORINATION
6-26.  Background.
    a.  Disinfection is the selective destruction of pathogenic  organ-
isms; sterilization is the complete destruction of all microorganisms.
Disinfection may be considered as one of the most important processes in
waste-water treatment.  This practice used in wastewater treatment has
resulted in the virtual disappearance of waterborne diseases.

    b.  Disinfection may be accomplished through the use of chemical
agents, physical agents, mechanical means, and radiation.   In wastewater
treatment, the most commonly used disinfectant is chlorine; however,
other halogens, ozone, and ultraviolet radiation have been used.

    c.  The rate of disinfection by chlorine depends on several  factors,
including chlorine dosage, contact time, presence of organic matter,
pH, and temperature.  The recommended chlorine dosage for disinfection
purposes is that which produces a chlorine residual of 0.5 to 1  mg/£
after a specified contact time.  Effective contact time of not less than
15 min at peak flow is recommended.  Typical chlorine dosages recommended
for disinfection and odor control are presented in Table 6-U.

    d.  The most common forms of chlorine used in wastewater treatment
plants are calcium and sodium hypochlorites and chlorine gas.   Hypo-
chlorites are recommended for small treatment plants where simplicity
and safety are more important than cost.  Chlorine gas may be applied as
a gas, or mixed with water to form a solution, a method used almost ex-
clusively in wastewater treatment.

    e.  The design of the chlorine contact tank plays an important role
in the degree of effectiveness produced from chlorination.  Factors
which must be considered in the design include method of chlorine addi-
tion, degree of mixing, minimization of short circuiting, and elimina-
tion of solids settling.  A recent study (para 6-33d) indicated that,
to minimize short-circuiting, the basin outlet may be designed as a
sharp-crested weir that spans the entire width of the basin outlet.
The longitudinal baffling of a serpentine flow basin was superior to
cross-baffling; a length-to-width ratio of Uo to 1 was necessary to
reach maximum plug flow performance regardless of the type of baffling.

6-21.  Input Data.

    a.  Chlorine contact tank influent flow, mgd.

                                6-35

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 EM 1110-2-501
 Part 1 of 3

 29  Sep 78

     b.   Peak  flow, mgd.


     c.   Average  flow, mgd.


 6-28.   Design Parameters.


     a.   Contact  time at maximum flow, min.


     b.   Length-to-width ratio.

     c.   Number of tanks.


     d.   Chlorine dosage, mg/£.


 6-29 •   Design Procedure^.


     a.   Select contact time at peak flow and calculate volume of contact
 tank.


                                 Q (CT) x 10
                           VPT1 =  P.
                           VC1     (210(60)

 where


    VCT = volume of contact tank, gal

     Q  = peak flow, mgd


     CT = contact time at maximum flow, min

    b.  Select a side water depth and calculate surface area.
                            SA = ,
                                 (7


where

                          2
     SA = surface area, ft

    VCT = volume of contact tank, gal

    SWD = side water depth *8 ft


                                 6-36

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                                                           EM 1110-2-501

                                                             Part 1 of 3
                                                                       O

                                                                        '
                                                              29 Sep 78


    c.   Select a length-to-width ratio and calculate dimensions.
                             CTW -
                             CTW ~
                             CTL = SA
                                   CTW
where


    CTW = contact tank width, ft

                          2
     SA = surface area, ft


    RLW = length-to-width ratio


    CTL = contact tank length, ft


    d.  Select chlorine dosage (Table 6-*0 and calculate chlorine

requirements.



                          CR = (Q   )(CD)(8.3U)
                                 avg



where


      CR = chlorine requirement, Ib/day


    Q    = average flow, mgd
     avg

      CD = chlorine dosage, mg/fc


    e.  Calculate peak chlorine requirements:
                             PCR = (CR)
                                        w
                                         avg



where


     PCR = peak chlorine requirements, lt>/day



                                  6-3T

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 EM 1110-2-501
 Part 1 of 3
  29  Sep  78
       CR = chlorine requirements,  It/day


       Q  = peak flow, mgd
     Qavg = averaSe

 6-30.   Output Data.


     a.   Maximum flow,  mgd.


     "b.   Average flow,  mgd.


     c.   Contact time,  min.


     d.   Volume of  contact tank, gal.


     e.   Average chlorine requirement, Ib/day.


     f.   Peak  chlorine  requirement, Ib/day.


     g.   Tank  dimensions.


6-31.  Example  Calculations.


     a.   Select  contact time and calculate volume of contact tank.



                                   Q (CT)106
                             •yPT1 _  P _
                             VCT ~  2* (60)


where


    VCT = volume of contact  tank,  gal


     Qp = peak flow,  2.0 mgd


     CT = contact time, 15 min
                                    2M6o)


                            VCT  =  20,833  pal


                                 6-38

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                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                                29 Sep 78
    b.  Select a side water depth and calculate surface area.
                                _   ,
                                  7A8(SWD)




where


                          2
     SA = surface area, ft



    VCT = volume of contact tank, 20,833 gal



    SWD = side water depth, 8 ft
                                  _ 20.833

                                  " 7.U8(8)
                               SA = 3^8 ft2
    c.  Select a length-to-width ratio and calculate dimensions,
                             CTW =






                             CTL =





where



    CTW = contact tank width, ft



     SA = surface a-rea, 3^8 ft



    RLW = ratio, length to width, 1



    CTL = contact tank length, ft
                             CTW =




                                 6-39
                                   CTW

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EM 1110-2-501

Part 1 of 3

29 Sep 78
                              CTW = 2.95 ft
                              CTT -
                              CTL ~
                                    2.95



                              CTL = 118 ft




    d.  Select chlorine dosage and calculate chlorine requirements.



                            CR = Qavg(CD)8.3U



where


      CR = chlorine requirements, Ib/day


    Q    = average flow, 1.0 mgd


      CD = chlorine dosage, 8 mg/£



                            CR = 1. 0(8)8. 3^


                            CR = 66.7 Ib/day



    e.  Calculate peak chlorine requirements.
                             PCR = CR



where
     PCR = peak chlorine requirements, Ib/day


      CR = chlorine requirement, 66.7 Ib/day


         = peak flow, 2.0 mgd
     avg
       P

         = average flow, 1.0 mgd

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78

                           PCB - 66.7(2$


                           PCR = 133.U Ib/day


6-32.  Cost Data.  Appropriate cost data and economic evaluation may be
found in Chapter 8.

6-33.  Bibliography.

    a.  American Society of Civil Engineers and the Water Pollution Con-
trol Federation, "Sewage Treatment Plant Design," Manual of Practice
No. 8, 1959, 1961, 1967, 1968, Water Pollution Control Federation,
Washington, D. C.

    b.  American Water Works Association, Water Quality and Treatment,
McGraw-Hill, New York, 1971.

    c.  Great Lakes-Upper Mississippi River Board of State Sanitary
Engineers, "Recommended Standards for Sewage Works (Ten States Stan-
dards)," 1971, Health Education Service, Albany, New York.

    d.  Marske, D. M. and Boyle, J. D., "Chlorine Contact Chamber
Design - A Field Evaluation," Water and Sewage Works, Vol 120, Jan 1973,
PP 70-77,

    e.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection,
Treatment, and Disposal, McGraw-Hill, New York, 1972.

    f.  Ruben, A. J., "Chemistry of Water Supply Treatment and Dis-
tribution," Ann Arbor Science, Ann Arbor, Michigan, 197^.

    g.  Sawyer, C. N. and McCarty, P. L., Chemistry for Sanitary
Engineers, McGraw-Hill, New York, 1967.

    h.  Smith, R., "Preliminary Design of Wastewater Treatment Systems,"
Journal, Sanitary Engineering Division,  American Society of Civil
Engineers, Vol 95, SA1, 1969, PP 117-118.

    i.  Water Pollution Control Federation, "Chlorination of Sewage and
Industrial Wastes," Manual of Practice,  No. 4,  1951.

    J.  Weber, W. J., Jr., Physiochemical Processes for Water Quality
Control, Wiley-Interscience, 1972.


                                 6-Ul

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EM 1110-2-501
Part 1 of 3
 29 Sep 78
                 Table 6-U.   Typical Chlorine Dosages  for
                       Disinfection and Odor Control
                                                              Dosage Range
	Effluent from	              mg/Jl

Untreated waste-water (prechlorination)                          6 to 25

Primary sedimentation                                           5 to 20

Chemical precipitation plant                                    2 to 6

Trickling filter  plant                                          3 to 15

Activated sludge  plant                                          2 to 8

Multimedia filter following activated sludge plant              1 to 5
                                           From Water Pollution Control Federation, 1961


                                   6-U2

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                                                           EM 1110-2-501
                                                              Part  1  of  3'
                                                               29 Sep 78

                         Section VI.   ION EXCHANGE

 6-3^.  Background.

     a.   Ion  exchange  is  the reversible  interchange of ions between a
 solid  ion-exchange medium  and a solution.  Ion exchange has been used
 extensively  in the removal of hardness  and iron and manganese  from
 ground-water  supplies.  In  wastewater  treatment, ion exchange has been
 used mainly  for the treatment of industrial wastes.  Recently, however,
 ion  exchange was evaluated for the removal of nitrogen and phosphorus
 from municipal wastes.

     b.   An ion-exchange  system usually  consists of the exchange resin
 (cation  or anion natural or synthetic), with provisions made for regen-
 eration  and  rinsing.  The  most commonly used regenerants include sul-
 fur ic  acid and caustic soda.  Prior to  application to the ion-exchange
 bed, wastewater may be subjected to pretreatment to remove certain con-
 taminants which may hinder the performance of the exchange bed.  Common
 pretreatment requirements are listed in Table 6-5.

 6-35.  Input Data.

     a.  Wastewater flow.

     (l)  Average flow, mgd

     (2)  Minimum and maximum flows, mgd.

    b.   Cation and anion concentrations, mg/£.

    c.   Allowable effluent concentrations,  mg/£.

6-36.  Design Parameters.

    a.   Type of resin.
                                      o
    b.   Resin exchange capacity,  Ib/ft  (manufacturer's  specifications).

    c.   Regenerant  dosage,  Ib/ft   (consult  resin manufacturer's
specifications).

    d.   Flow rates.

    (1)  Treatment  flow rate  (2-5  gpm/ft3).

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EM 1110-2-501
Part 1 of 3
 29.6ep 78

    (2)   Regenerant  flov rate  (1-2  gpm/ft  ).

    (3)   Rinsing flow rate  (0.5-1.5 gpm/ft  ).

    e.  Amount  of rinse  water  (30-120  gal/ft  ).

    f.   Column  depth (2*1-30 in.  minimum).

    g.   Operation per day,  hr.
                                        3
    h.   Amount  of backwash  water,  gal/ft .

    i.   Regenerant level, Ib/ft  .

    j.   Regenerant concentration,  percent.

    k.   Regenerant specific gravity.
                                   2
    1.   Backwash water rate, gpm/ft .

6-37.   Design Procedure.

    a.   Select  an ion-exchange system (consult manufacturer's
specifications).

    b.   Select  leakage,  regenerant dosage, exchange capacities, and
flow rates (consult manufacturer's specifications).

    c.   Compute service volume and time.
                                ""   IRC


where

    IRC = (influent concentration - allowable effluent concentration)
     SV = service volume, gal/ft

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                                                            EM 1110-2-501
                                                              Part 1 of 3
                                                               29 Sep 78
     REG  =  resin exchange capacity,  Ib/ft

     IRC  =  ion removal  concentration,  Ib/gal
                                 orp _  _§V
                                 ST "  SFR


where


     ST  =  service  time, min

                                 •3
     SV  =  service  volume,  gal/ft


    SFR  =  service  flow rate,  gpm/ft


    d.   Compute volume of  resins.
                    Vol


where
=  |IRC(Q)(106)1   f   ST   1
   L    REG    J   L(60)(2MJ
                             •3
    Vol = volume of resin, ft


    IRC = ion removal concentration, l~b/gal


      Q = total flow, mgd

                                        Q
    REG = resin exchange capacity, l"b/ft


     ST = service time, min


    e.  Calculate volume of regenerant.


                     v  =      RL x Vol x (100)
                      R   RC(8.3*0 (specific gravity)
where
     V  = volume of regenerant, gal

     RL = regenerant level, Ib/ft
                                 6-U5

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EM 1110-2-501

Part 1 of 3

 29  Sep  78

                             3
    Vol = volume of resin, ft


     RC = regenerant concentration, percent


    f.  Compute rinse requirements.



                             VRW = RW x Vol



where


    VRW = volume of rinse water, gal


     RW = rinse water, gal/ft


    Vol = volume of resin, ft


    g.  Compute "backwash water requirements.



                             VBW = (BW)(Vol)



where


    VBW = "backwater requirements,  gal


     BW = backwash water, gal/ft

                             3
    Vol = volume of resin, ft


    h.  Compute exchange  cycle time.



                      EC  = ST + BT + RT + WT + OMT



 where


     EC = exchange cycle, min


      ST = service time, min


     BT = backwash time,  min


      RT = regeneration time, min



                                  6-1*6

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                                                           EM 1110-2-501
                                                             Part 1  of 3

                                                              29 Sep 78^

     WT = rinse time, min


    OMT = operation and maintenance time, hr


 and


     ST = service time, min

     RT - M
     BT ~ BR
                                o
     BW = backwash water, gal/ ft

                                     Q
     BR = rate of backwashing, gpm/ft


           V
     prp _ _ £1 v  -L
     RT " RRF   Vol

     VR = volume of regenerant

                                         •3
    RRF = rate of regenerant flow, gpm/ft

                             3
    Vol = volume of resin, ft
          RRW
                             3
    VRW = rinse water, gal/ ft


    RRW = rate of rinse water flow, gpm/ft

    OMT = 0.10(ST + BT + RT + WT)


    i.  Calculate number of cycles per day.
                          P  i  ix     HPD(60)
                          Cycles /day = —  - '-
where  HPD = operation per day, hr


6-38.  Output Data.


    a.  Average waste flow, mgd.


    b.  Effluent concentration, mg/&.

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EM 1110-2-501

Part 1 of 3

29 Sep 78

                                      2
    c.  Resin exchange capacity, l"b/ft .

                               2
    d.  Regenerant level, l"b/ft .

                                   2
    e.  Treatment flow rate, gpm/ft .

                                    2
    f.  Regenerant flow rate, gpm/ft .

                               2
    g.  Rinse flow rate, gpm/ft .

                                  2
    h.  Backwash flow rate, gpm/ft .


    i.  Volume of regenerant, gal.


    j.  Volume of rinse water, gal.


    k.  Volume of "backwash water, gal.

                           2
    1.  Volume of resin, ft .


    m.  Service time, min.


    n.  Exchange cycle, min.


    o.  Cycles per day.


    p.  Service volume, gal/ft .


    q.  Backwash water, gal/ft .

                           2
    r.  Rinse water, gal/ft .


6-39-  Example Calculations.


    a.  Select an ion exchange system from manufacturer's

specifications.


    b.  Select leakage, regenerant dosage, exchange capacities, and
flow  rates from manufacturer's specifications.


    c,  Compute service volume and time.



                                     REG
                                SV =
                                     IRC


                                  6-U8

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                                                           EM 1110-2-501
                                                             Part  1 of 3

                                                               29 Sep 78

where

                                o
     SV = service volume, gal/ft

                                          Q
    REG = resin exchange capacity, 1| Ib/ft


    IRC = ion removal concentration =  (influent concentration - effluent


          concentration) —-—  ,Q	
                 IRC =  (200 mg/£ - 2 mg/£) °'62^ ^10
                 IRC = 1.6$ * 10 3 lb/gal
                  sv =	u lb/ft3
                       1.65 x 10 3 lb/gal
                  SV = 21+24 gal/ft3
                     -  SV
                     ~ SFR
where


     ST = service time, min


     SV = service volume, 2^24 gal/ft


    SFR = service flow rate, 3 gpm/ft
                                     3


                              ST = 808 min

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EM 1110-2-501
Part 1 of 3

 29  Sep  78

    d.  Compute volume of resins.
                      Vol =
                                        x r  ST  i
                                          [60(2U)J
                                REC



where


    Vol = volume of resin, ft


    IRC = ion removal concentrate, 1.65 x 10   Ib/gal


      Q = average flow, 1.0 mgd

                                          o
    REC = resin exchange capacity, U Ib/ft"


     £T = service time,
                 Vol  = [(1.65  x  10-3)(1.0)1061  x  ffiOS
                       231.5 ft3
     e.  Calculate volume of regenerant.
                         =	RL(Vol)lOO
                       R   RC(8.3*0 (specific gravity)



 where


      VT, = volume of regenerant,  gal
       K
                                      2
      RL = regenerant level, 7-5 Ib/ft


     Vol = volume of resin, 231.5 ft


      RC = regenerant concentration, 7-5 percent



                                  6-50

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                                                            EM 1110-2-501
                                                              Part 1 of 3

                                                                29 Sep 78
     specific gravity = specific  gravity of regenerant,  1.0^


                            v  =  T.5(231.5)100
                             R   7.5(8.3U)1.0U


                            VR =  2668  gal
     f.   Compute  rinse  requirement.


                              VR¥ = RW(Vol)


where

     VRW  = volume of rinse water, gal

     RW  = rinse water, 60 gal/ft

     Vol  = volume of resin, 231.5 ft3


                            VRW = 60(231.5)

                            VRW = 13.890 gal


     g.   Compute backwash water requirements.


                              VBW = BW(Vol)


where

    VBW = "backwash requirements,  gal

     BW = backwash water, 100 gal/ft

    Vol = volume of resin,  231.5  ft3


                            VBW = 100(231.5)

                            VBW = 23.150


                                 6-51

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EM 1110-2-501

Part 1 of 3


 29 Sep 78


    h.  Compute exchange cycle time.




                      EC = ST + BT + RT + WT + OMT




where



     EC = exchange cycle, min
     ST =  service time, oOo min



     BT =  backwash time = :r— = ——• = 6.7 mi
                          is K    Lj



     RT =  regeneration time = RRF(*ol) = L5(^3?.5) = T-7 min




     WT =  rinse time = —— = -—- = 60 min
                       nnw   -L.U


    OMT =  0.10(ST + BT + RT + WT)




         EC = 808 + 6.7 + 7-7 + 60 + 0.10(808 + 6.7 + 7.7 + 60)



         EC = 970.6k min
     i.  Calculate number of cycles per day.




                           _   .,   ,,     HPD(60)
                           Cycles/day = —g£	-




where



     HPD =  operation per day,  16 hr



     EC =  exchange cycle time, 970.6h min




                           n   l   Ix      16(60)
                           Cycles/day =   Q  ^





                           Cycles/day =0.99








                                   6-52

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78

6-UO.  Cost Data.  Appropriate cost data and economic evaluation may be
found in Chapter 8.

6-1*1.  Bibliography.

    a.  Gulp, R. L. and Gulp, G. L., Advanced Wastevater Treatment,
Van Nostrand, New York, 1971.

    b.  Eckenfelder, W. W., Jr., Industrial Water Pollution Control,
McGraw-Hill, New York, 1966.

    c.  Kunin, R., Ion Exchange Resins, 2d ed., Wiley, New York, 1958.

    d.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection,
Treatment, and Disposal, McGraw-Hill, New York, 1972.

    e.  Sanks, R. L., "ion Exchange," Seminar on Process Design for
Water Quality Control, 9-13 Nov 1970, Vanderbilt University, Nashville,
Tenn.

    f.  Weber, W. J., Jr., Physiochemical Processes for Water Quality
Control, Wiley-Interscience, New York, 1972.
                                 6-53

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EM 1110-2-501
Part 1 of 3

 29  Sep  78
              Table 6-5.  Common Pretreatment Requirements
   Contaminant
Suspended solids


Organic



Oxidants

Iron and manganese
       Effect
Bind resin particles
Large molecules foul
  strong base resins
Slowly oxidize resins

Coat resin particles
       Removal
Coagulation and
  filtration

Carbon absorption or
  weak base resins
  only

Avoid prechlorination

Aeration.
                                 6-5U
                                                             From Banks, 1970

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78

                      Section VII.  NEUTRALIZATION

6-U2.  Background.

    a.  Neutralization is a unit operation in which pH adjustment of
highly acidic or highly alkaline wastewaters takes place.   Neutrali-
zation of such wastes is necessary prior to:

    (l)  Biological waste treatment where the optimum pH for bacterial
activity (pH 6.5-8.5) must be maintained.

    (2)  Chemical treatment to provide an optimum pH for the reaction.

    (3)  Disposal to the receiving streams.

Neutralization is applied mainly to the treatment of industrial wastes.

    b.  There are many acceptable methods for the neutralization of
acidic and alkaline wastes.  Acidic wastes may be neutralized by reac-
tion with caustic soda, lime, or by passing the wastewater through a
limestone bed.  Neutralization through limestone beds may be accom-
plished through upflow or downflow systems.   A maximum hydraulic rate
of 1 gpm/ft  is recommended for downflow systems to ensure sufficient
retention time (para 6-^9a).  Maximum acid concentration of 0.6 percent
HgSO^ is suggested to avoid coating the limestone with nonreactive cal-
cium sulfate and to prevent excessive evolution of carbon dioxide, both
of which limit complete neutralization.  Higher hydraulic rates may be
used for upflow beds since the products are swept out before precipita-
tion.  However, the disposal of exhausted limestone beds may be a seri-
ous drawback to this method of neutralization.

    c.  Mixing acid wastes with lime slurries is an effective means of
neutralization.  The reaction is similar to that obtained with limestone
beds.  Lime is relatively inexpensive and possesses a high neutralizing
power.  Hydrated lime may produce a problem in handling since it has a
tendency to arch or bridge over the outlet in storage bins and has poor
flow characteristics.  Both caustic soda and sodium carbonate are more
powerful than lime, and the reaction products are soluble and do not
increase the hardness of the receiving waters.

    d.  Alkaline wastes can be neutralized with acid (mostly sulfuric
or hydrochloric), with flue gas containing lU percent carbon dioxide,
or with bottled carbon dioxide.  Carbon dioxide will form carbonic acid
when dissolved in water which will neutralize alkaline wastes.   The


                                  6-55'

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 EM 1110-2-501
 Part 1 of 3
 29 Sep 78

 reaction  is  slow, but  sufficient, if the desired pH is near 7 or 8.  The
 use  of acid  to neutralize alkaline vastes is fairly common.  The reac-
 tion rate  is almost instantaneous.  A titration curve of the alkaline
 waste neutralized with various amounts of acid is helpful to ascertain
 the  quantities of acid required for neutralization.

     e.  The  selection of a pH control system may prove to be one of the
 most  troublesome tasks facing the design engineer because of the follow-
 ing  factors  (para 6-h9h):

     (l)  The relation between the amount of reagent and pH is nonlinear.

     (2)  The  input pH can vary rapidly over a range of several decades
 in a  short time.

     (3)  The flow can change while the pH is changing, and the two are
 not related.

     (h)  The pH at neutrality is so sensitive to the addition of reagent
 that a  slight excess can cause large deviations from the setpoint.

    (5)  Measurement of the pH can be affected by materials which coat
the electrodes.

    (6)  The buffer capacity of the waste has a profound effect  on the
relation between reagent feed and pH and may not remain constant.

    f.  Several types of pH control schemes  have been  applied in waste
neutralization systems, including manual control,  open loop control,
closed loop systems, combined open and closed loop systems,  feedback
control, and feed forward  control.

    g.  Figure 6-h shows an acid-waste neutralization  system.

6-U3.  Input  Data.

    a.  Wastewater flow.

    (l)  Variations in waste flow (maximum and  minimum), mgd.

    (2)  Average daily flow,  mgd.

    b.  pH ranges at various  waste  flows.
                                6-56

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                                                            EM 1110-2-501
                                                              Part 1 of 3
                                                                29 Sep 78
               QUICKLIME FEEDER
               AND SLAKER
                                             SLURRY STORAGE TANK
             WASTE
              AGIO
       EQUALIZING
       TANK OR
       LAGOON
                 SOLENOID VALVE
                 AND pH CONTROL
                                                         MIXER
                               •PH CONTROLLER
                 ALKALINE WASTE
TO LAGOON
OR DISPOSAL
SYSTEM
                                               From Eckenfelder, Jr., 1970
       Figure 6-U.  Schematic of acid-waste neutralization  system.


    c.  Acidity or alkalinity, mg/Jl.

6-hh.  Design Parameters.

    a.  Desired pH level and range-.

    b.  Buffer capacity.

    (l)  Pound reagent/gallon waste  to  neutralize to desired pH (from
titration curves).

    (2)  Flow rate, depth, and concentration  of feed for limestone
neutralization (from laboratory investigation).

    c.  Residence time  (depends on the  degree of mixing).
    d.  Degree of mixing  (hp/1000  gal)  (manufacturer, 0.2-O.U hp/1000
gal).
                                 6-57

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 EM 1110-2-501

 Part 1 of 3

 29  Sep 78



 6-1*5-   Design Procedure.


     a.   Select reagent.



     (l)  Acid waste  (limestone bed or lime slurries or caustic soda).



     (2)  Alkaline wastes  (sulfuric or hydrochloric acids, carbon dioxide
 gas).



     b.   For limestone beds, select depth of bed and rate of flow (from

 laboratory investigation) and calculate surface area.




                                  Q    x 106
                                =
                                  (2U)(60)FR

where

                           o
      SA = surface area, ft


    Qavg = average flow, mgd
      FR = flow rate, gpm/ft2



    c.  Calculate reagent feed using flow data and titration curves.




                            RF = (Q)(R)(106)


where



    RF = reagent feed rate, Ib/day



     Q = waste flow, mgd



     R = buffer capacity, Ib reagent/gal waste to neutralize to desired

         PH



    d.  Calculate volume of mixing tank.





                       Vol =
                                 6-58

-------
                                                           EM 1110-2-501
                                                             Part 1 of ^
                                                                29 Sep  78

where
                                   3
    Vol = volume of mixing tank, ft

      Q = waste flow, mgd

      a = mixing time, min (from manufacturer, 5-10 min)

    e.  Calculate horsepower for mixing:


                      .   _ (HPR)(Vol)(7.U8 gal/ft3)
                      np            (1000)

where

     hp = horsepower

    HPR = horsepower for mixing per 1000 gal (0.2-O.U hp/1000 gal)

    Vol = volume of mixing tank, ft

    f.  For feedback control,  a  may "be calculated "by equation pro-
posed by Greer (para 6-1*9d):
     9A
AA = -3T
                                              t\
                                            -—I
                                              a/
where
    AA = allowable deviation in acidity or alkalinity from a given set
         point in the effluent

    — = maximum rate of acidity or alkalinity change in feed to the
         unit

     t = overall process lag time = reaction time + measurement and
         transport lag («0.5 min)

     a = minimum nominal residence time (time required for perfectly
         mixed basin to give process controllability)

    g.  Calculate  a  and apply a factor of safety of 2-3.


                                 6-59

-------
EM 1110-2-501
Part 1 of 3

29 Sep 78

6-46.  Output Data.

    a.  Buffer capacity, Ib/day.

                                 •3
    b.  Volume of mixing tank, ft  .

    c.  Detention time, min.

    d.  Horsepower.

6-1*7.  Example Calculations.  Design of a neutralization system is de-
pendent upon conducting a laboratory investigation; therefore, no design
example calculations will be presented in this section.

6-^8.  Cost Data.  Appropriate cost data and economic evaluation may be
found in Chapter 8.

6-^9.  Bibliography.

    a.  Eckenfelder, W. W., Jr., Water Quality Engineering for Practic-
ing Engineers, Barnes and Nobel, New York, 1970.

    b.  Eckenfelder, W. W., Jr., and Ford, D. L., Water Pollution Con-
trol, Pemberton Press, New York,- 1970.

    c.  Field, W. B., "Design of a pH Control System by Analog Simula-
tion," Instrument Society of American Journal,  Vol 6,  1959, pp 42-50.

    d.  Greer, W. N., The Measurement and Control of pH. Leeds and
Northrup, Philadelphia, 1966.

    e.  Hoak, R.  D., "Acid Iron Wastes Neutralization," Sewage and
Industrial Wastes,  Vol 22, No.  2, 1950, pp 212-221.

    f.  Nemerow,  N.  L., Liquid Waste of Industry, Addison-Wesley,
Reading,  Mass.,  1971.

    g.  Shinskey, F. G., "Feed Forward Control  of pH," Instrumentation
Technology,  Vol  15,  1968.

    h.  Wallace,  A.  T., "Neutralization and pH  Control," 1st Short
Course on Design  of Wastewater Treatment,  1970, Vanderbilt ttoiversity,
Nashville, Tenn.
                                 6-60

-------
                                                          EM 1110-2-501
                                                             Part  1  of  3

                                                              29 Sep 78
                      Section VIII.   RECARBONATION
6-50.  Background.
    a.  Recarbonation is a unit process that has long been used in lime-
softening water treatment plants.   In water treatment, recarbonation is
usually practiced ahead of the filters to prevent calcium carbonate de-
position on the grains which will  result in shortening of the filter
runs.  Recarbonation is also used  to lower the pH of the lime-treated
water to the point of calcium carbonate stability to avoid deposition of
calcium carbonate in pipelines.

    b.  More recently, with the increased use of lime treatment of
wastewaters, recarbonation has been more widely used in wastewater
treatment.  Recarbonation, in wastewater treatment,  is mainly used to
adjust the pH following lime treatment for such applications as phospho-
rus removal, ammonia stripping, or chemical clarification.

    c.  Recarbonation may be practiced as either a two-stage or a
single-stage system.  Two-stage recarbonation consists of two separate
treatment steps.  In the first stage, sufficient carbon dioxide is added
in the primary recarbonation stage to lower the pH of the wastewater to
pH = 9-3, which is near the minimum solubility of calcium carbonate.
The sludge produced, which is mainly calcium carbonate, is then removed
through settling and recalcined if recovery of the lime is desired.   The
time required to complete the reaction is normally 15-30 min.  In the
second stage, carbon dioxide is added to lower the pH to a value of
pH = 7.  It is possible, however,  to add sufficient  carbon dioxide to
lower the pH from 11 to 7 in a single stage.  Single-stage recarbonation
eliminates the need for an intermediate settling basin which is needed
in the two-stage system.  However, single-stage recarbonation normally
results in an increase in the calcium hardness of the water.

    d.  The reactions involved in  the recarbonation process may be
simplified as follows:

                      Ca(OH)2 + CO  -> CaCO  + HO


                      CaC03 + C02  + H20 -> Ca(HCO )2

    e.  The amount of C02 needed to complete the reactions, as calcu-
lated from the equations above is  as follows:


                                 6-61

-------
 EM 1110-2-501

 Part  1  of  3

 29 Sep  78



    Calcium hydroxide to calcium carbonate



    C02  (It/million gal) = 3.7  (OH~ alkalinity in mg/£, as CaCO  )



    Calcium carbonate to calcium bicarbonate



    C02  (Ib/million gal) = 3.7  (CO^ alkalinity in mg/£ as CaCO  ).


 6-51.  Input Data.



    a.  Wastewater flow.



    (l)  Average flow.



    (2)  Peak flow.



    b.  Wastewater characteristics.



    (l)  Alkalinity.



    (2)  Hydroxide alkalinity, mg/£ as CaCO .



    (3)  Carbonate alkalinity, mg/£ as CaCO_.



    c.  pH.



6-52.   Design Parameters.



    a.  Contact time,  min (15-30).



    b.  Carbon dioxide dose,  lb/million gal.



    c.  Desired effluent pH.



6-53.   Design Procedure.



    a.  Two-stage.



    (l)   Primary stage to  pH  = 9.3.



    (a)   Calculate tank volume,   V  = Q.lt)1P\
                                      60(24)
                                 6-62

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
where

    V = tank volume, gal

    Q = wastewater flow, mgd

    t = contact time, min (15-30)

    ("b)  Calculate CO  requirement.

                     C00 = (3.7)(OH~(Q)/0.116/1UUO)
where
      CO  = carbon dioxide requirement, cfm/mgd

      3.7 = stochiometric value to convert hydroxide to carbonate

      OH~ = hydroxide alkalinity, in mg/£ as CaC03

        Q = wastewater  flow, mgd

     0.116 = density  of  C00, Ib/ft
           = min/day

     (2)   Secondary stage to  pH  =  7-

     (a)   Calculate tank volume,   V =   o

 where

     V =  volume,  gal

     Q =  wastewater flow, mgd

     t =  contact  time,  min (15-30  min)

     ("b)   Calculate C0p requirement.
                        = 3.7(C03 + OH
                                  6-63

-------
 EM 1110-2-501
 Part 1 of 3
 29 Sep 78
 where

     C03 = carbonate alkalinity,  mg/£ as CaCO

     OH  = hydroxide alkalinity,  mg/£ as CaCO

       Q = wastewater flow,  mgd

     "b.   Single-stage recarbonation to pH =  7.

     (l)   Calculate  volume of  tank.


                            V  = (Q)(t)/6o/lUo

where

    V = volume, million gal

    t = contact time, min (5-30 min)

    (2)   Calculate C0  requirements.
            C02(cfm/mgd) = 7.MOH~) + 3.7 (CO^) (Q)/0. 116/1^0


where

    OH  = hydroxide alkalinity, mg/£ as CaCO

    C03 = carbonate alkalinity, mg/£ as CaCO

6-5^.  Output Data.

    a.   Volume of tank,  million gal.

    b.   Carbon dioxide requirement,  cfm/mgd.

    c.   Final pH.

    d.   Contact time,  min.
                               6-6h

-------
6-55-  Example Calculations.

    a.  Two-stage.

    (l)  Adjust primary stage to pH = 9-3.

    (a)  Calculate tank volume.
where

    V = volume of tank, million gal

    Q = average flow, 1.0 mgd

    t = detention time, 15 min
                                                          EM  1110-2-501
                                                            Part  1  of  1
                                                              29 Sep 78
                                   60(2U)



                            V = 10,^16 gal


     (b)  Calculate CO  requirement.


                                 =  3.7(OH")Q
                             OU2   0.1l6(lUUo)


where

       CO  =  carbon dioxide requirement, cfm/mgd

       3.7 =  stochiometric value to convert hydroxide to carbonate

       OH~ =  hydroxide alkalinity, 50 mg/£

        Q =  average  flow, 1.0 mgd


                                 6-65

-------
 EM 1110-2-501

 Part 1 of 3


 29 Sep 78



     0.116 = density of CO ,  lb/ft3
           = minutes per day
                            ro   = 3.7(50)(i.Q)

                             2     0.116(]MO)"
                            CO   =  1.1  cfm/mgd
     (2)   Adjust  secondary  stage  to pH = 7.



     (a)   Calculate  tank  volume.
                               v -
                                 ~
                                    2M6o)


 where



    V = volume of tank, gal



    Q = average  flow, 1.0 mgd



    t = detention time, 15 min
                             v =
                                   2k(60)




                             V = 10,Ul6 gal




    (b)  Calculate C02 requirement.






                                3.7(003 + OH~)Q


                          C°2     0.1l6(lltUo)




where




    C02 = carbon dioxide requirement,  cfm/mgd




                                 6-66

-------
                                                          EM  1110-2-501
                                                            Part  1  of  3
                                                               29  Sep 78
    3.7 =  stochiometric value to  convert C03 or OH  to  carbonate

    C0~ =  carbonate  alkalinity, 150 mg/2.

    OH~ =  hydroxide  alkalinity, 50 mg/£

      Q =  average  flow, 1.0 mgd

                            = 3.7(150 +  50)1.0
                         UU2      0.1l6(lUUO)
                         CO  = k.k cfm/mgd


6-56.  Cost Data.   Appropriate cost data and economic evaluation may be
found in Chapter 8.

6-57.  Bibliography.

    a.  American Water Works Association, "Water Quality and Treatment,"
3rd edition, McGraw-Hill Book Co., 1971-

    b.  Gulp, R. L. and Gulp, G. L., "Advanced Wastewater Treatment,"
Van Nostrand Reinhold Company, 1971

    c.  Sawyer, C. N. and McCarty, P. L., "Chemistry for Sanitary Engi-
neers," McGraw-Hill Book Company, 2nd edition, 1967.
                                  6-67                (next page  is  6-69)

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78

                  Section IX.  TWO-STAGE LIME TREATMENT

6-58.  Background.

    a.  Two-stage treatment systems are used for phosphorus removal from
waste-waters.  In principle, for a two-stage system, sufficient lime is
added to the waste-water in the first stage to raise the pH to above 11.
At this pH precipitation of hydroxy-apatite, calcium carbonate, and
magnesium hydroxide takes place.   Carbon dioxide is then added following
the first-stage clarifier to reduce the pH to a value of 9-5-10, where
calcium carbonate precipitation results.  The sludge, which is mainly
CaCOo, is then separated in a clarifier and the pH of the wastewater is
adjusted to around 7 for further treatment or final disposal.  A flow
diagram of a two-stage lime treatment system is presented in Figure 6-5.

    b.  The design of a two-stage lime treatment system will be a com-
bination of (l) chemical coagulation-precipation basin using lime as a
coagulate; (2) a primary recarbonation stage; (3) a clarifier designed
as a primary clarifier; and  (U) a secondary recarbonation stage.

6-59.  Chemical Coagulation.

    a.  Input data.

     (l)  Wastewater flow, mgd.

     (a')  -Average daily flow, mgd.

     (b)  Variation in flow, mgd.

     (2)  Wastewater characteristics.

     (a)  BOD, total and soluble, mg/£.

     (b)  COD, total and soluble, mg/£.

     (c)  Phosphorus, mg/X,.

     (d)  Suspended solids, mg/Jl.

     (e)  pH.

     (f)  Alkalinity, mg/£.
                                  6-69

-------
                                                                                                    to
                                                                                                    VO
                                                                                                        P S

                                                                                                        c+ H
                                                                                   WASTE
                                                                                 WASHWATER
cr\
                                                                                 WASHWATER
                                      SLUDGE TO RECALCINATOR
                                           OR DISPOSAL
                                                                                                    00
                                 O
                               O I
                               i-b ro

                               u) vn
                                 o
          LIME
                             Figure 6-5-  Two-stage lime treatment syst
em,

-------
                                                          EM 1110-2-501

                                                            Part 1 of  3


                                                               29  Sep 78
    b.   Design parameters.



    (l)  Desired quality of treated effluent, mg/fc.



    (2)  Coagulant dosage,  mg/£ (jar test).



    (3)  Detention time of rapid mix basin (1-3  min).



    (U)  Detention time of flocculator basin (15-60 min).



    c.   Design procedure.



    (l)  Calculate coagulant requirements.




                          CR = (CD)(Q   )(8.3U)
                                     avg



where



      CR = coagulant requirements, Ib/day



      CD = coagulant dosage, mg/&



    Q    = average daily flow, mgd
     avg


    (2)  Calculate volume of flash mixing basin.




                                (Q )(DTFM)(10 )


                                  T      	
where



     VFM = volume of flash mix basin, gal



      Q  = peak flow, mgd



    DTFM = detention time of flash mixer, min (l-3 min)



    (3)  Calculate volume of flocculator basin.





                                (Q )(DTFL)(10 )

                          VFL = —2-
                                 6-71

-------
 EM 1110-2-501-
 Part 1 of 3

29 Sep 78

 where

      VFL = volume  of flocculator basin, gal

       Q  = peak flow, mgd

     DTFL = detention time  of  flocculator basin, min  (15-60 min)

 6-60.   Primary  Clarifier.

     a.   Input data.

     (l)   Wastewater  flow.

     (a)   Average flow, mgd.

     (b)   Peak flow,  mgd.

     (2)   Wastewater  characteristics.

     (a)   Suspended solids, mg/£.

     (b)   Volatile  suspended solids, percent.

     b.   Design  parameters.
                              Q
     (l)   Overflow  rate, gpd/ft .  (Tables 6-6 and 6-1.)

     (2)   Detention time, hr.  (Table 6-7.)

     (3)   Specific  gravity  of  sludge.  (Table 6-8.)

     (M   Solids content of underflow, percent (h to 6 percent).

     (5)   Removal efficiency of suspended solids, percent.  (Fig. 6-6.)

     (6)   Weir loading, gpd/ft (10,000 to 15,000 gpd/ft).

     c.   Design procedure.

     (l)   Select an overflow rate by using Table 6-6 or by laboratory
 methods  and calculate surface area:
                                 6-J2

-------
                                                    EM 1110-2-501
                                                      Part 1 of 3
                                                       29 Sep 78
BO
70
J
SOLIDS REMOV
en
o
Q
Q 40
Z
UJ
a.
D
30
20
10C
O
0
. *
• 0
.

o MEDIAE
LESS T
RATES






O
0 •

0 0
\
\
0 \
°\ ,
^

o
/ LINE OMITTING
HAN 35% AND OVE
LESS THAN 300 G



,
.




O
o •
1 ° O
\
\
\
• o\
• >
REMOVALS") /
•RFLOW \^
PD/SO FT J



O

•
LEG
END
• RECTANGULAR TANKS
0 CIRCULA!


•

X
\





=i TANKS






^•^ •
• ^











) 500 1000 1500 2000 2500
                   OVERFLOW RATE, GPD/SQ FT

Figure 6-6.  Suspended solids removal versus overflov rate
                 for secondary clarifiers.
                          6-73

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78
where
                          2
     SA = surface area, ft

     Q  = peak flow, mgd
                               o
    OFR = overflow rate, gal/ft/day

    (2)  Select detention time and calculate volume (Table 6-7)
where

       V = volume of tank, ft

    Qavg = average flow, mgd
       t = time, hr

    (3)  Calculate side water depth:
where

    SWD = side water depth, ft
      V = volume, ft
                          2
     SA = surface area, ft

         Check solids loading rate:

                               (Q0,,J(SSI)(8.3M
                         SLR = -

-------
                                                           EM 1110-2-501

                                                             Part 1 of 3


                                                               29 Sep 78

where

                                     2
     SLR = solids loading rate, Ib/ft /day


    Q    = average flow, mgd


     SSI = influent solids concentration, mg/£

                           2
      SA = surface area, ft



    (5)  Select weir loading rate and calculate weir length:
where


     WL = weir length, ft


     Q  = peak flow, mgd


    WLR = weir loading rate, gal/ft/day


    (6)  Determine percentage of suspended solids removed from Fig-

ure 6-6.


    (T)  Calculate amount of primary sludge produced.




                   PSP = (Qavg)(SSl)(SSR)(lO~2)(8.3^)




where


     PSP = primary sludge produced, Ib/day


    Q    = average flow, mgd


     SSI = influent solids concentration,  mg/H (50 to  60 percent for

           municipal systems)


     SSR = suspended solids removed, percent





                                 6-75

-------
 EM 1110-2-501
 Part  1  of 3
29 Sep 78

     (8)  Select underflow concentration (3 to 6 percent)  and sludge
 specific gravity (Table 6-8),  and calculate the volume flow of primary
 sludge produced:


                    VPSP =	PSP(10D)	
                           (specific gravity)(UC)(8.


 where

     VPSP = volume flow of primary sludge produced,  gal/day

      PSP = primary sludge produced, gal/day

       UC = underflow concentration (3 to 6 percent)

 6-6l.  Recarbonat ion.

     a.   Input data.

     (l)  Wastewater flow.

     (a)  Average flow.

     (b)  Peak flow.

     (2)  Wastewater characteristics.

     (a)  Alkalinity.

     (b)  Hydroxide alkalinity,  mg/£ as CaCO_.

     (c)  Carbonate alkalinity,  mg/£ as CaCO_.

     (3)  pH.

     b.   Design parameters.

     (l)  Contact time,  min (15-30).

     (2)  Carbon dioxide dose, Ib/million gal.

     (3)  Desired effluent pH.
                                 6-76

-------
                                                          EM 1110-2-501
                                                            Part 1 of 3

                                                              29 Sep 78

    c.  Design procedure for two-stage.


    (l)  Primary stage to pH = 9-3

    (a)  Calculate tank volume.



                              v - Q(t)io6
                                "
where


    V = tank volume, gal


    Q = wastewater flow, mgd


    t = contact time, min (15-30)


    (b)  Calculate C0p requirement.



                      C02 = (3.7)(OH~)(Q)/0.1l6/lUUo



where


      3.7 = stochiometric value to convert hydroxide  to  carbonate


      OH  = hydroxide alkalinity, mg/£ as


        Q = wastewater flow, mgd


    0.116 = density of C0 , lb/ft3
          = min/day


    (2)  Secondary stage to pH = 7.


    (a)  Calculate tank volume.
                                   2U(6o)
                                 6-77

-------
 EM 1110-2-501
 Part 1 of 3
29 Sep 78
 where

    V =  volume, gal

    Q =  wastewater flow, mgd

    t =  contact time, min (15-30 min)

    (b)  Calculate C0_ requirement.


                    C02 = 3.7(CO:r + OH~)(Q)/O.H6/lMK)


 6-62.  Primary Clarifier.

    a.   Input data.

    (l)  Wastewater flow.

    (a)  Average flow, mgd.

    (b)  Peak hourly  flow, mgd.

    (2)  Suspended solids, mg/£.

    (3)  Volatile suspended solids, percent.

    b.   Design parameters.

    (1)  Overflow rate, gpd/ft2.   (Tables 6-6 and 6-7.)

    (2)  Detention time, hr.   (Table 6-7.)

    (3)  Specific gravity of  sludge.   (Table 6-8.)

    (k)  Solids content of underflow,  percent (k to  6 percent).

    (5)  Removal efficiency of suspended  solids, percent.   (Fig. 6-6.)

    (6)  Weir loading, gpd/ft (10,000  to  15,000 gpd/ft).

    c.   Design procedure.
                                  6-78

-------
                                                            EM 1110-2-501

                                                              Part  1  of  3

                                                              29 Sep 78


     (l)   Select  an  overflow rate  "by using  Table  6-6  or "by laboratory

 methods  and calculate  surface  area.
                               SA =
                                       x  106
                                      OFR



where


                           2
     SA =  surface  area,  ft
 Q  = peak flow, mgd


 FR = overflow rate,


(2)  Select detention time and calculate volume (Table 6-7),
    OFR = overflow rate, gal/ft2/day
where

                             •3
       V = volume of .tank, ft



    Qavg = averaSe flow'' mSd


       t = time, hr


    (3)  Calculate side water depth.





                                SWD = S

where


    SWD = side water depth, ft

                    •3
      V = volume, ft

                          p
     SA = surface area, ft


    (U)  Check solid loading rate.




                                6-79

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78
                               (Qm  )(SSI)(8.3U)
                         SLR = -
                                     (SA)

where
                                    o
     SLR = solid loading rate, Tb/ft /day

    Q    = average flow, mgd
     avg                  &
     SSI = influent solids concentration, mg/£
                           o
      SA = surface area, ft1"

    (5)  Select weir loading rate and calculate weir length.
where

     WL = weir length, ft

     Q  = peak flow, mgd
      P
    WLR = weir loading rate, gal/ft/day

    (6)  Determine percentage of suspended solids removed from Table 6-6.
    (7)  Calculate amount of primary sludge produced.

                   PSP = (Qavg)(SSl)(SSR)(lO~2)(8.3M

where

     PSP = primary sludge produced, Ib/day
    Q    = average flow, mgd
     avg               >  &
     SSI = influent solids concentration, mg/£ (50 to  60 percent for
           municipal systems)

                                 6-80

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
     SSR = suspended solids removed, percent
    (8)  Select underflow concentration (3 to 6 percent) and sludge
specific gravity (Table 6-8), and calculate the volume flow of primary
sludge produced.
                   VPSP =
                           (specific gravity) (UC)(8. 3M

where

    VPSP = volume flow of primary sludge produced,  gal/day

     PSP = primary sludge produced,  gal/day

      UC = underflow concentration (3 to 6 percent)

6-63.  Output Data.

    a.  Coagulation process.

    (l)  Coagulant dosage,  mg/£.

    (2)  Optimum pH.

    (3)  Rapid mix detention  time, min.

    (H)  Flocculator detention time,  min.

    (5)  Coagulant requirement,  Ib/day.

    (6)  Volume of flash mix  basin,  gal.

    (7)  Volume of flocculator basin,  gal.

    b.  Clarifier.

    (1)  Overflow rate,  gal/day ft2.
                         i")
    (2)  Surface area,  ft .

    (3)  Side water  depth,  ft.
                                 6-81

-------
EM 1110-2-501

Part 1 of 3


29 Sep 78

     (U)   Detention time, hr.


     (5)   Solid loading,  Ib/ft  /day.


     (6)   Weir loading, gal/ft/day.


     (7)   Weir length,  ft.


     (8)   Volume of  sludge  produced,  gal/day.


     (9)   Suspended  solids  removal, percent.


     c.   Recarbonation unit.


     (l)   Volume of  tank, million gal.


     (2)   Carbon dioxide  requirement, cfm/mgd.


     (3)   Final pH.


     (U)   Contact time, min.


     d.  Clarifier.

                                   2
     (1)  Overflow rate,  gal/day ft .

                          2
     (2)  Surface area, ft .


     (3)  Side water depth, ft.


     (U)  Detention time, hr,

                              2
     (5)  Solid loading, Ib/.ft /day.


     (6)  Weir  loading,  gal/ft/day.


     (7)  Weir  length, ft.


     (8)  Volume of sludge produced, gal/day.


      (9)   Suspended solids removal,  percent.


     e.   Recarbonation unit.




                                   6-82

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3..
                                                               29  Sep  78
    (l)  Volume of tank, million gal.
    (2)  Carton dioxide requirement, cfm/mgd.
    (3)  Final pH.
    (h)  Contact time, min.
6-64.  Example Calculations.
    a.  Chemical coagulation.
    (l)  Calculate coagulant requirements.

                           CR = CD(Qavg)8.3U

where
      CR = coagulant requirements , Ib/day
      CD = coagulant dosage, 100 mg/£
    Q    = average flow, 1.0 mgd

                           CR = 100(1. 0)8. 3^
                           CR = 83^ Ib/day

    (2)  Calculate volume of flash mixing basin.

                                 Q (DTFM)IO
                           VFM = -£ — -
where
     VFM = volume of flash mixing tank, gal
      Q  = peak flow, 2.0 mgd

                                 6-83

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EM 1110-2-501
Part 1 of 3
29 Sep 78
     DTFM = detention time flash mixing tank,  5  min

     1440 = min per day
                                  =  694*+  gal


     (3)   Calculate volume of flocculator "basin.


                                  Q  (DTFL)IO
                            VFL =  P     -
 where

      VFL =  volume  of  flocculator basin,  gal

       Q  =  peak flow,  2.0 mgd

     DTFL =  detention  time flocculator  basin,  30 min
                            VFL =  Ul.667  gal


     b.   Primary  clarifier.

     (l)   Select  an  overflow rate and  calculate  surface area.
                              SA=
                                       x  106
                                 6-8^

-------
where

                          2
     SA = surface area, ft


     Q  = peak flow, 2.0 mgd


    OFR = overflow rate, 600 gpd/ft
                                   2
                             SA = —
                                     600



                             SA = 3333 ft2



    (2)  Select detention time and calculate  volume.



                                 Q™ (t)io6
                             V =
where


       V = volume, ft
    Q    = average flow,  1.0 mgd


       t = detention time,  3 hr
                              v -
                              V ~
                              V = 16,711 ft2
    (3)   Calculate  side water  depth.
                               SWD = -v
                                     SA
                                6-85
                                                          EM 1110-2-501

                                                            Part 1 of 3

                                                              29 Sep  78

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EM 1110-2-501

Part 1 of 3

29 Sep 78
 where
     S¥D = side water depth,  ft


       V = volume,  l6,Tll ft3

                                 2
      SA = surface  area,  3,333 ft
                               SWD = 5.0 ft




     (U)   Check solids loading rate.





                            SLR =
                                       SA

 where

                                      2
      SLR = solids loading rate, l"b/ft /day


     Q    = average flow, 1.0 mgd


      SSI = influent suspended solids, 200 mg/fc


       SA = surface area, 3333 ft2
                            QTP - 1.0(200)8.
                            SLR ~     3333
                            SLR =0.5 Ib/ft2day
     (5)  Select weir loading rate and calculate weir length.

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                                                          EM 1110-2-501
                                                            Part 1 of 3

                                                             29 Sep 78
where

     WL = weir length, ft

     Q  = peak flow, 2.0 mgd

    WLR = weir loading rate, 15,000 gpd/ft
                              WL -
                                    15,000

                              WL = 133 ft
    (6)  Determine percentage of suspended solids removal.   Percentage
suspended solids removed = 65 percent.

    (7)  Calculate amount of primary sludge produced.


                      PSP = Q   (SSI)SSR(10~2)8.3U
                             avg

where

     PSP = primary sludge produced,  Ib/day

    Q    = average flow, 1.0 mgd
     avg

     SSI = influent suspended solids,  200 mg/£

     SSR - suspended solids removed, 68 percent


                      PSP = 1.0(200)(68)10~2(8.3M

                      PSP = 113^ Ib/day
    (8)  Select underflow concentration and sludge specific  gravity and
calculate the volume of primary sludge produced.
                                 6-87

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EM 1110-2-501
Part 1 of 3
29 Sep 78
                          . 	PSP(lOO)
                          " specific gravity(UC)8.
 where

                VPSP = volume of primary sludge produced, gal/day

                 PSP = primary sludge produced, 113U Ib/day

     specific gravity = l.Oh

                  UC = underflow concentration, h percent


                          vpqp =  113M1QQ)
                                 1.0M108.3U

                          VPSP = 3268 ffpd


    c.  Recarbonation.

    (l)  Primary stage pH = 9.3.

    (a)  Calculate tank volume.
                             v = Q(t)io6
                                  2M6o)
where

    V = volume, gal

    Q = average flow,  1.0 mgd

    t = detention time,  15 min
                            v =
                                  2M60)

                            V = 10,ia7 gal


                                6-88

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                                                          EM 1110-2-501
                                                            Part 1 of 3

                                                              29 Sep  78
    (b)  Calculate CO  requirement.
where

      CQ  = carbon dioxide requirement, cfm/mgd


      3,7 = conversion factor, by dioxide to carbonate


      OH~ = hydroxide alkalinity, 50 mg/£


        Q = average flow, 1.0 mgd


    0.116 = density of C0, lb/ft3
                                  3.7(50)1.0
                                  0.1l6(iMo)
                            CO  =1.1 cfm/mgd
     (2)  Secondary stage to pH = 7.

     (a)  Calculate tank volume.



                               v _ Q(t)io6
                               V " 2U(60)


where

     V  = volume of tank, gal

     Q  = average  flow,  1.0 mgd

     t  = detention time, 15

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 EM 1110-2-501
 Part  1  of  3
 29  Sep  78

                             v _ 1.0(15)106
                             V ~   2M60)

                             V = 10,1*17 gal


    (b)  Calculate C0? requirement.


                               3.7(00^ + OH~)Q
                         C°2 =   0.116(1UUO)

where

      CO  = carbon dioxide requirement, cfm/mgd

      3.7 = stochiometric conversion factor CO-, and OH  to carbonate

      CO  = carbonate alkalinity, 150 mg/£

      OH~ = hydroxide alkalinity, 50 mg/£

        Q = average flow, 1.0 mgd

    0.116 = density of CO , lb/ft3

                         rn  - 3.7(150+ 50)1-0
                           2 ~   0.116(1UUO)

                         CO  = k.k cfm/mgd
    d.  Primary clarifier.  The primary clarifier for use after recar-
bonation is designed in the same manner as the clarifier for use after
the coagulation chamber.

6-65.  Cost Data.  Appropriate cost data and economic evaluation may be
found in Chapter 8.
                                  6-90

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                                                          EM 1110-2-501
                                                            Part 1 of 3
                                                               29 Sep  78

6 66   Bibliography.   A bibliography  for  each unit process needed in
tvo-stage lime treatment is presented at  the end  of  each of those sec-
tions; namely, chemical coagulation,  primary clarification, and
recarbonation.
                                   6-91

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EM 1110-2-501
Part 1 of 3
 29 Sep 78
               Table 6-6.  Recommended Surface-Loading Rates
                          for Various  Suspensions
                                              Loading Rate, gpd/ft2   ~~_	
	Suspension	                    Range                   P_eak_Flow

Untreated wastewater                 600 to 1200                  1200
         Q
Alum floe                             360 to  600                    600
         Q
Iron floe                             5^0 to  800                    800

Lime floe                             5^0 to 1200                  1200

a  !,»•   =   -j_,  .,     . , -,   , ,                       (From Metcalf and Eddy, Inc..  1971
   Mixed with  the settleable suspended  solids  in the untreated waste-
  water and  colloidal or other suspended solids swept out by the floe.
                  Table 6-7.   Detention Times  for Various
                   Surface-Loading Rates and Tank Depths

Surface-Loading
Rate




, gpd/ft^
Uoo
600
800
1000





7-
De
3.
2.
1.
1.

ft
pth
2
1
6
25
Detention
8- ft
Depth
3.6
2.1*
1.8
1.1*
Time,
hr
10- ft
De

3.
2.
1.
pth

0
25
8

12
De
5
3
2
2

-f+
pth
)i
6
.7
. 2
                                                  (From Metcalf and Eddy, Inc., 1971)
               Table  6-8.   Specific Gravity of Raw Sludge
                  Produced from Various Types of  Sewage
Type of
Sewerage System
Sanitary
Sanitary
Combined
Combined
Strength
of Sewage
Weak
Medium
Medium
Strong
Specific
Gravity
1.02
1.03
1.05
1.07
                                                  (From Metcalf and Eddy, Inc., 1971)


                                  6-92

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78

                                CHAPTER 7

                        BIOLOGICAL UNIT PROCESSES

                        Section I.  INTRODUCTION

7-1.   Definition.   Processes that employ biokinetic or biochemical
reactions as a principal means of treatment fall into the category
"biological unit processes."  The following biological unit processes
are described in this section.

    a.  Trickling filters.

    b.  Plug flow activated sludge.

    c.  Complete mix activated sludge.

    d.  Step aeration activated sludge.

    e.  Extended aeration activated sludge.

    f.  Modified or high-rate aeration activated sludge.

    g.  Contact stabilization activated sludge.

    h.  Pure oxygen activated sludge.

    i.  Aerated aerobic lagoons.

    j.  Aerated facultative lagoons.

    k.  Oxidation ditch.

    1.  Nitrification-denitrification.

    m.  Aerobic digestion.

    n.  Anaerobic  digestion.

    o.  Stabilization ponds.

    (l)  Aerobic.

    (2)  Anaerobic.

    (3)  Facultative.


                                  7-1                  (next page is 7-3)

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                                                          EM  1110-2-501
                                                            Part  1  of  3
                                                               29 Sep 78

                     Section II.   TRICKLING FILTERS

7-2.  Background.

    a.  Trickling filters were one of the earliest forms of  waste-water
treatment used in the United States.   They are classified as low-  or
high-rate filters, depending on the hydraulic loading (l-k mgad for  low,
10-1*0 mgad for high).  In the trickling filtration process wastewater
is distributed uniformly over the filter media "by a flow distributor.
The majority of such units use a reaction drive rotary distributor.   A
large portion of the wastewater rapidly passes through the filter; the
remainder slowly trickles over the slime layer formed on the filter
surface.  BOD removal is achieved by biosorption and coagulation from
the rapidly moving portion of the flow and by progressive removal  of
soluble constituents from the more slowly moving portion of  the flow.

    b.  The quantity of biological slime produced is controlled by the
available food; the growth will increase as the organic load increases
until a maximum effective thickness is reached.  The maximum growth  is
controlled by physical factors including hydraulic dosage rate, type
of media, type of organic matter, amount of essential nutrients present,
oxygen transfer, and nature of the particular biological growth
(para 7-9r).  The microbiology of trickling filters can be found in
the bibliography (para 7-9k, p, and r).  Various recirculation systems
used with trickling filters are shown in Figure 7-1.

    c.  The use of recently developed synthetic media has increased
the popularity as well as the capability of trickling filters  in domes-
tic wastewater treatment.  The granite stone medium is rarely  used in
modern sewage treatment systems due to its higher capital costs (com-
pared with synthetic media) and other limitations such as growth of
filter flies, odor, and ponding problems (para 7-9c and o).   Thus only
the synthetic medium filter tower will be designed here.

7-3.  Input Data.

    a.  Wastewater flow.

    (l)  Average daily flow, mgd.

    (2)  Peak hourly flow, mgd.

    b.  Influent BOD, mg/£
                                  7-3

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EM  1110-2-501
Part 1 of 3
29 Sep  78
                                   SINGLE-STAGE FILTERS
                                              RECYCLE
                                   TWO-STAGE FILTERS
                        FIRST-STAGE RECYCLE
                                                 SECOND-STAGE RECYCLE
                                                       From Clark and Viesmann, 1966

     Figure 7-1.  Various systems  of recirculation  used  with  trick-
                                   ling filters.

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                                                           EM 1110-2-501
                                                             Part 1 of 3

                                                               29 Sep 78

    c.   Desired effluent BOD,  mg/£.


    d.   Temperature, °C.


    e.   Recirculation ratio.


7-l|.  Design Parameters.


    i.   Reaction rate constant,  k  (0.0015-0.003) (from laboratory).
    a.
    b.  Specific surface area of the media, ft2/ft3, from manufacturer

= Ap (9-35).


    c.  Media factor = n (from laboratory).

                                 /~\
    d.  Hydraulic loading, gpm/ft  = Q  (from laboratory).


    e.  Sludge production factor = PF (0.1*2-0.65) lb solids/lb


7-5.  Design Procedures.


    a.  Calculate the desired depth of the filter.


                                           S
                                             + S(R) 1
                                             + S(R) J
     D = depth of filter, ft

                                  2
    Q  - hydraulic loading, gpm/ft
     o

     n = media factor


     S = desired effluent BOD   mg/£


     R = recirculation ratio =  Q  /Q


    3  = influent BOD^, mgA
     o                j

     K = reaction rate constant

                                                2
    A  = specific surface area  of the  media,  ft /ft"
     P
                                  7-5

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 EM 1110-2-501
 PartJL  of 3
 29 Sep  78
 Height  must be  checked against   D <  30  ft.   If   D >_ 30  ft,  select  a
 lower hydraulic  loading (Q  )  and recalculate D  .  ~
    b.   Calculate the  surface area of the  filter.
                                  QilkkO]
                            SA = -S2&	
where
                           2
      SA =  surface area, ft

    Q&   =  average daily flow, mgd

      QQ =  hydraulic loading, gpm/ft
    ikkO =  min per day

    c.  Calculate the filter media volume.

                                V = SA(D)
where
                            o
     V = volume of media, ft
                         2
    SA = surface area, ft
     D = filter depth, ft
    d.  Calculate sludge production.

                          SP = Q   (S )PF(8.3M
                                avg  o
where

      SP =  sludge produced, Ib/day

    Qa   = average daily flow, mgd
      S  = influent BODr, mg/H
       o               5'  e"
      PF = sludge production factor, Ib solids/lb BOD
                                  7-6

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                                                           EM 1110-2-501
                                                             Part 1 of 3.

                                                              29 Sep 78


7-6.   Output Data.


    a.  Depth of filter, ft.

                                  2
    b.  Surface area of filter, ft .


    c.  Volume of filter, ft .

                                 2
    d.  Hydraulic loading, gpm/ft .


    e.  Recirculation ratio.


    f.  Sludge production, Ib/day.


 7-7.  Example Calculations.


    a.  Calculate desired depth of the filter.


                                         + S(R) 1
                        u           KA

 where


      D = depth of filter,  ft
                                                 2
     Q  = hydraulic loading to filter,  1.0  gpm/ft
      o

      n = 0.5


      S = 15 i


     S  = 200
      o

      R = recirculation ratio, 100 percent, 1,0


      K = reaction rate, 0.0022 ft/min

                                      2   3
     A  = specific surface area, 30 ft /ft
      P
                           n n^°-5 m f  15 + ^d-o)
                           (1.0)    in [_ 20Q + 15(1.0)
                     D   "         0.0022(30)
                                   1-1

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 EM 1110-2-501

 Part  1  of  3



 29 Sep  78


                         D = 29.8 ft, say  30 ft



    "b.  Calculate surface area of filter.



                                 Q
where


                           p

      SA = surface area, ft



    Q    = average flow, 1.0 mgd
     avg

                                        Q
      Q  = hydraulic loading, 1.0 gpm/ft
                              SA = iMd ft



    c.  Calculate volume.



                                V = SA(D)



where



     V = volume of filter, ft



    SA = surface area, ih'kO ft2



     D = depth, 30 ft



                              V = 1MK)(30)



                             V = J43,200 ft3



    d.  Calculate sludge produced.




                          SP = Q   (S  )PF(8.3U)
                                avg  o


where



      SP = sludge produced, Ib/day

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                              29 Sep  78

    Q    =  average  flow,  1.0 mgd
     avg
      S  =  influent BODC, 200 mg/A
       o               ?
      PF =  sludge production factor,  O.H5  Ib solids/lb BOD


                         SP = 1.0(200)0.U5(8.3M

                             SP = 730 lb/day

7-8.  Cost  Data.  Appropriate cost  data and economic evaluation  may be
found in Chapter 8.

7-9.  Bibliography.

    a.  American Society of Civil Engineers and the Water Pollution
Control Federation, "Sewage Treatment Plant Design," Manual of Practice
No. 8, 1959, 1961,  1967, 1968,  Water Pollution Control Federation, Wash-
ington, D.  C.

    b.  Baker, J. M. and Graves, Q. B., "Recent Approaches for Trickling
Filter Design," Journal, Sanitary Engineering Division, American Society
of  Civil Engineers, Vol 9^, SA1, Feb 1968, pp 65-8U.

    c.  Benjes, H.  H., "Small Community Wastewater Treatment Facilities -
Biological Treatment Systems,"  prepared for the Environmental Protection
Agency, Technology Transfer National Seminar on Small Wastewater Treat-
ment  Systems, March 1977-

    d.  Brown, J.  C. et  al., "Methods for  Improvement of  Trickling
Filter Plant Performance - Part I, Mechanical and Biological Optima,"
Report No. 670/2-73-OU7a, Aug 1973, U. S.  Environmental Protection
Agency, Washington, D. C.

    e.   Clark, J.  W. and Viessman, W., Jr., Water Supply  and Protection
Control, International Textbook Co., Scranton, 1966.

     f.   Dow  Chemical Company,  "A Literature  Search  and Critical  Anal-
ysis  of Biological Trickling Filter  Studies  - Vols  I  and  II," Report
No. 17050-DDY, Dec 1971, U. S.  Environmental Protection Agency,  Wash-
ington, D.  C.
                                   7-9

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 EM 1110-2-501
 Part  1 of 3
 29 Sep 78

     g.   Eckenfelder,  W.  W.,  Jr.,  "Trickling Filter Design and Perfor-
 mance," Transactions, American Society of Civil Engineers  Vol 128
 Part  III, 1963,  pp 371-39**.                               '

    h.   Eckenfelder,  W.  W.,  Jr.,  Water Quality  Engineering  for Prac-
 ticing Engineers,  Barnes and Nobel,  New York, 1970.

    i.   Eckenfelder,  W.  W.,  Jr.,  and Earnhardt,  W.,  "Performance  of a
 High-Rate Trickling Filter Using  Selected Media,"  Journal,  Water  Pollu-
 tion  Control^Federation,  Vol 35,  No.  12,  1963,  1535-1551.

    J.   Eckenfelder,  W.  W.,  Jr.,  and Ford,  D. L.,  Water Pollution
 Control,  Pemberton Press, New York,  1970.

    k.  Fair, G. M.,  Geyer,  J.  C., and Okun, D.  A., Water Purification
 and Wastewater Treatment  and Disposal:  Water and Wastewater Engineering
 Vol 2,  Wiley, New  York,  1968.

    _1.  Galler, W.  A.  and Gotaas, H.  B. ,  "Analysis of Biological  Filter
 Variables," Journal,  Sanitary Engineering Division, American  Society  of
 Civil Engineers, Vol  90, SA6,  196*1, pp  59-79.

    m.  Germain, J.,  "Economic  Treatment of Domestic Waste  by Plastic-
 Medium  Trickling Medium Filters," 38th  Annual Conference, Water Pollu-
 tion Control Federation, Oct  1965, Atlantic City, N. J.

    n.  Great Lakes-Upper Mississippi River Board of State  Sanitary
 Engineers,  "Recommended Standards for Sewage Works (Ten State Stan-
 dards),"  1971, Health  Edi—^ -> Service. Albany, N  v

    o.  Liptak, B. G., Environmental Engineers'  Handbook, Volume  I, Water
 Pollution, Chiltori Book Co.,  197*1, Radnor, Pa.

    p.  McKinney, R. E., Microbiology for Sanitary Engineers. McGraw-
 Hill, New York, 1962.	

    q.  National Research Council, "Trickling Filters (in Sewage Treat-
ment at Military Installations)," Sewage Works  Journal. Vol 18, No. 5
19U6, PP 787-1028.

    r.  Roy F. Weston, Inc.,  "Process Design Manual for Upgrading Exist-
ing Wastewater Treatment Plants," prepared for  the  U. S.  Environmental
Protection Agency, Technology Transfer, Oct 1971, Washington,  D. C.
                                  7-10

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                                                          EM  1110-2-501
                                                            Part  1  of  3
                                                               29  Sep 78

    s.   Schulze, K.  L.,  "Load and Efficiency of  Trickling  Filters,"
Journal, Water Pollution Control Federation, Vol 32,  No. 3,  PP 2^5-261.

    t.   Velz, C. J., "A Basic Law for the Performance of Biologic
Beds," Sewage Works  Journal, Vol 20, No.  3,  I960, pp  2U5-261.
                                                     (next page is 7-13)

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                                                           EM 1110-2-501
                                                             Part  1  of  3
                                                              29 Sep 78
                Section III.   PLUG FLOW ACTIVATED SLUDGE
7-10.   Background.

    a.  Activated sludge is definecf as "sludge floe  produced in raw
or settled wastewater by the growth of zoogleal bacteria and other
organisms in the presence of dissolved oxygen and accumulated in suffi-
cient concentration by returning floe previously found."  Similarly,
the activated-sludge process is defined as "a biological wastewater
treatment process in which a mixture of wastewater and activated sludge
is agitated and aerated."  The activated sludge is subsequently sepa-
rated from the treated wastewater (mixed liquor) by sedimentation and
wasted or returned to the process as needed (para T-l8a).

    b.  In the past few decades, many modifications of this process have
been developed, although only two process variations are significant:
the conventional system, which achieves absorption, flocculation, and
synthesis in a single step; and contact stabilization during which oxi-
dation and synthesis of removed organics occur in a separate aeration
tank.

    c.  In the following paragraphs,  seven activated sludge process mod-
ifications and variations will be considered:  conventional plug flow,
complete mix, step aeration, modified-aeration or high-rate, contact
stabilization, extended aeration, and pure oxygen system.  While other
modifications of the activated sludge process exist (namely tapered aera-
tion  and the Kraus process) they will not be  included in this chapter.

7-11.  Plug Flow Activated  Sludge.

    a.  The plug flow activated  sludge process uses an  aeration tank, a
settling tank, and a sludge return  line to treat wastewater  (fig.  7-2).
     INFLUENT
                  AERATION TANK
                 SLUDGE RETURN
rSETTUNG\ EFFLUENT
  TANK


             WASTE
                                                          SLUDGE
                 Figure 7-2.   Plug flow activated sludge.
                                  7-13

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EM 1110-2-501
Part 1 of 3
29 Sep 78

    "b.  Wastewater and returned sludge from the secondary clarifler
enter the head of the aeration tank to undergo a specified period of
aeration.  Diffused or mechanical aeration is used to provide the
necessary oxygen and adequate mixing of the influent waste and recycled
sludge, the concentration of which is ^ligh at the head of the tank and
decreases with aeration time.  Absorption, flocculation,  and synthesis
of the organic matter take place during aeration.  The mixed liquor
(sludge floe plus liquid in the aeration tank) is settled in the secon-
dary clarifier, and sludge is returned at a rate sufficient to maintain
the desired mixed liquor suspended solids in the aeration tank.

    c.  Process design parameters and design examples are found in para-
graph 7-l8c, h, o, and t.

1-12.  Input Data.

    a-  Wastewater Flow (Average and Peak).   In case of high variability,
a statistical distribution should be provided.

    b.  Wastewater Strength.

    (1)  BOD  (soluble and total), mg/£.

    (2)  COD and/or TOC (maximum and minimum), mg/£.

    (3)  Suspended solids, mg/£.

    (4)  Volatile suspended solids (VSS), mg/£.

    (5)  Nonbiodegradable fraction of VSS, mg/£.

    c.  Other Characterization.

    (1)  pH.

    (2)  Acidity and/or alkalinity, mg/£.

    (3)  Nitrogen,1 mg/£.

    (4)  Phosphorus (total and soluble),  mg/£.
   The form of nitrogen should be specified as  to  its  biological
  availability (e.g.,  NH  or Kjeldahl).


                                 7-14

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                                                          EM 1110-2-501
                                                            Part 1 of  ^
                                                               29 Sep 78


   (5)  Oils and greases, mg/i.


   (6)  Heavy metals, mg/£.

   (7)  Toxic or special characteristics  (e.g., phenols), mg/£.


   (8)  Temperature, °F or  °C.

   d.  Effluent ^Quality Requirements^


   (1)  BOD  , mg/£.

   (2)  SS,  mg/£.

   (3)  TKN, mg/£.

    (U)  P, mg/fc.

    (5)  Total nitrogen (TKN + NO  - N), rng/,'i.

    (6)  Settleable solids,  ing/2/hr.


7-13.   De_sig_n Parameters^

    a.  Reaction rate constants and coefficients (aveia^e values to be
used  in absence  of specific data).

              Constants
                 k                   0.0007 to 0.002 Jl/mg/hr


                 a                          0.73

                 a'                         0.52

                 b                          0.075/day


                 f                          O.U

                 b1                         0.15/day


                 f                         0.53



                                  7-15

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EM 1110-2-501


Part 1 of 3


29 Sep 78




    b.  Organic leading,  F/M  ratio,




        F/M = (0.2-0.4)




    c.  Volumetric loading (ib BOD /1000 ft3/day).




        Range 20-140




    d.  Hydraulic detention time,  t .




        t - (4-8) hr




    e.  Solids retention time,  t
                             J   c;



        t  = (5-15) days
         b



    f.  Mixed liquor suspended solids concentration,  MLSS




        MLSS = (1500-3000) mg/£




    g.  Mixed liquor volatile suspended solids,  MLV3S.




        MLVSS =0.7 MLSS




              =  (1050-2100) mg/£




    h.  Recycle  ratio,   Qr/0 .




        Qr/Q = (0.25-0.5)




    i.  Oxygen requirements,  Ib 0 /Ib BOD  .

                                 2      r



        Ib 0 /Ib BOD >  1.25
            2       r —



    j.   Sludge production, Ib solids/]b BOD  .

                                          r


        Ib solids/lb BOD  = 0.5-0.7




    k.   Temperature coefficient,   0  .




        6 =  1.0-1.03




    1.   BOD  removal efficiency  (80-90 percent).









                                7-16

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                                                           EM 1110-2-501
                                                             Part  1 of 3
                                                               29  Sep 78

    m.   Return sludge concentration.

7-lU.   Design Procedure (Eckenfelder's Approach).

    a.   Assume the following design parameters from 7-13 when unknown.

    (l)  BOD removal rate constant (k).

    (2)  Fraction of BOD synthesized  (a).

    (3)  Fraction of BOD oxidized for  energy (a1).

    (k)  Endogenous respiration rate  (b and b').

    (5)  Mixed liquor suspended solids (MLSS).

    (6)  Mixed liquor volatile suspended solids (MLVSS).

    (7)  Food-to-microorganism ratio  (F/M).

    (8)  Nonbiodegradable fraction of  VSS  in influent (f).

    (9)  Degradable fraction of the MLVSS  (f).

   (10)  Temperature correction coefficient (0).

    "b.   Adjust  k  for temperature.

                                     fT-20)
                            KT = K20G
where
     K  = rate constant at desired temperature,  °C

    K   = rate constant at 20°C

      0 = temperature correction coefficient

      T = temperature, °C

    c.  Determine the size of the aeration tank  by first determining
the detention time.
                                 7-17

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EM 1110-2-501
Part 1 of 3
    29  Sep  78
                             t =
                                 (Xy)(F/M)
where
      t = hydraulic detention time, hr
     S  = influent BOD, mg/l
     Xy = MLVSS, mg/£
    F/M = food-to-microorganism ratio
    d.  Check the detention time for treatability.
                                   .
                             S  = S e
                              e    o
where
    S  = BOD  (soluble) in effluent, mg/£
    S  = BOD  in influent, mg/£
     k = BOD removal rate constant ,  £/mg/hr
    X^ = MLVSS, mg/£
     t = detention time, hr
Solve for  t  and compare with  t  from above and select the larger.
    e.  Calculate the volume of aeration tank.

                             V = Q    x ^~
                                 ^avg   2k
where
       V = volume of tanks, million gal

    Q    = average -daily flow, mgd
     avg
       t - detention time, hr

                                 7-18

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                                                           EM  1110-2-501
                                                             Part  1  of  3
                                                                   29 Sep 78
    f.  Calculate oxygen requirements.


                            dt" ~ ~~t   + bIXV
or

                02 = a'(Sr)(Qavg')(8.3M + b'(Xy)(V)(8.3M

where
    dO/dt = oxygen uptake rate, mg/£/hr
       a' = fraction of BOD oxidized for energy
       S  = BOD removed (S  - S ), mg/£
        t = detention time, hr
       b' = endogenous respiration rate,/hr
      Xy = MLVSS, mg/£
      0  = oxygen required, Ib/day
    Q    = average daily flow, mgd
       V = volume of aeration tank, million gal
and check the oxygen supplied per pound of BOD removed >1.25.

                                          CU
                      lb 0^/lb BOD  =
where
    0  = oxygen required, Ib/day
     Q = flow, mgd
    S  = BOD removed, mg/£
    g.  Design aeration system.

                                  7-19

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EM 1110-2-501
Part 1 of 3
  29 Sep 78

    (l)  Diffused aeration system.

    (a)  Assume the following design parameters.

    !_  Standard transfer efficiency (from manufacturer), 5-8 percent
       (coarse bubble diffuser).

    2.  02 transfer in waste/0  transfer *in water  a£.9 = a .

    3.  02 saturation in waste/0  saturation in water  %0.9 = 3 .

    k_  Correction factor for pressure  ssL.O = p .

    (b)  Select summer operating temperature (25-30°C) and determine
         (from standard tables)  0  saturation.

    (c)  Adjust standard transfer efficiency to operating conditions.


                          [(CS)T(8)(P) -C]
                OTE = STE 4=	i-£-^	^ a(l.02)T~20


where

      OTE = operating transfer efficiency, percent

      STE = standard transfer efficiency, percent

    (cs)T = °2 saturation at selected summer temperature  T ,  °C,

        3 = 02 saturation in waste/0  saturation in water ;^0.9

        p = correction factor for pressure s»1.0

       C  = minimum dissolved oxygen to be maintained in the  basin
        L   >2.0 me '
            02 transfer in waste/0  transfer in water %0.9

        T = temperature, °C

    (d)   Calculate required air flow.
                                 7-20

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                                                           EM 1110-2-501

                                                             Part  1 of 3


                                                                  29  Sep 78
                Pi  ~
                 'a
                     (OTE %} (0.0176

                                    ftj air
    R  - required air flow, cfm/1000 ft
     a


     V =•- volume of the basin, gal



    (2)  Mechanical aeration system.



    (a)  Assume the following design parameters.



    1  Standard transfer efficiency, Ib/hp-hr (0 dissolved oxygen,

20°C and tap water),



    2  0  transfer in waste/0^ transfer in water ss£>.9.
    ~   2                    ^


    3  0  saturation in waste/0,, saturation in water «£).9-
    —   2                      d


    k  Correction factor for pressure «sl.O.
    (b)  Select summer operating temperature (25-30°C) and determine

         (from standard tables) 0  saturation.




    (c)  Adjust standard transfer efficiency to operating conditions,






                           [(Cs) (6)(P) - C  ]
                           L.    J          J-l .J   /-. s-\ f~* \ -1- t—vy
                OTE = 3TE



where



      OTE = operating transfer efficiency, Ib 00/hp-hr




      STE = standard transfer efficiency, Ib 02/hp-hr



     (Cs),  = 0  saturation at selected summer temperature, mg/£




        3=0^ saturation in waste/0  saturation  in water «0.9




        p = correction factor for pressure «1.0





                                 T-21

-------
KM 1110-2-501
Part 1 of 3
29 Spp 78
     T - miniiiiun  Ussolved oxygen to be maintained in the basin
                                   0
                                       /o), W i r ~
                                        ^ 4   v'
                                          	 x 1000
where
                                                  Q(SS -
      ".\ - r,].-f1^,e  11 educed, Ib/d&y


        s. = ij'a/jiioK of liOD removed synthesized to cell material

      ?  -: BOD  r<--T^.Y< "• .  n;~;'k.
       b - endogenous respiration ra^e/day

       V - volume  of aeration tank, million  gal

       Q - flow, mgd

     7SS = volatile suspended solid:-- in  effluent,

-------
                                                           EM 1110-2-501

                                                             Part 1 of 3


                                                                 29 Sep 78


     f = non'biodegrada'ble fraction of VSS in influent



    SS = suspended solids in effluent, mg/£



Check  AX^  solids produced against pounds of BOD removed (0.5-0.7).



                           .              AX.r
                 (Ib solids) = _ _V _

                  (Ib BOD )    S (Q)(8.3U)(# volatile)
                         r      r



    i.  Determine nutrient requirements  (ib/day)



for nitrogen



                              N = 0.123AXy



and phosphorus



                              P = 0.026AXy



and check against BOD:N:P = 100:5:1.



    j.   Calculate sludge recycle ratio.





                                       X
                                        a
                              Q      X   - X
                              avg    u    a
where
       Q  =  volume  of  recycled sludge, mgd
        r


     Q    =  average flow,  mgd
      avg


       X  =  MLSS, mg/£
        a


       X  =  SS concentration of returned sludge,  mg/Ji
        u


     k. Calculate  solids  retention time.



                                 (V)(X )(8.3U)

                           SRT = -    a
                                      AX
                                        a
 where





                                  7-23

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EM 1110-2-501
Part 1 of 3
 29 Sep 78
    SRT = solids retention time, days
      V = volume of aeration tank, million gal
     X  = MLSS, mg/£
        —
      a   % volatile
    1.  Calculate effluent BOD .
                   BOD      = S  + (0.8M(V\   (f)
                                         V v/
                                             eff
where
         S  = effluent soluble BODC , mg/£
          e                       5
    (Xy} „ , = volatile solids in effluent, mg/£
         f = degradable fraction of the MLVSS
T-15.  Output Data.
    a.  Aeration Tank.
    (l)  Reaction rate constant, £/mg/hr.
    (2)  Sludge produced per BOD removed.
    (3)  Endogenous respiration rate (b, b' )
    (U)  0  utilized per BOD removed.
    (5)  Influent nonbiodegradable volatile suspended solids (VSS)(f)
    (6)  Effluent degradable volatile suspended solids  (f1)-
     (7)  lb BOD/lb MLSS-day  (F/M ratio).
     (8)  Mixed liquor  suspended solids, mg/£  (MLSS).
     (9)  Mixed liquor  volatile suspended  solids, mg/£ (MLVSS ).
                                 7-2U

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                                                           EM 1110-2-501
                                                             Part  1  of  3
                                                                 29 Sep 78

    (10)   Aeration time,  hr.

    (11)   Volume of aeration  tank,  million gal.

    (12)   Oxygen required,  Ib/day.

    (13)   Sludge produced,  Ib/day.

    (lU)   Nitrogen requirement,  Ib/day.

    (15)   Phophorus requirement, Ib/day.

    (16)   Sludge recycle  ratio,  percent.

    (IT)   Solids retention  time, days.

    b. Diffused Aeration System.

    (l)  Standard transfer  efficiency, percent.

    (2)  Operating transfer efficiency, percent.

    (3)  Required air flow, cfm/1000 ft3.

    c. Mechanical Aeration System.

    (l)  Standard transfer  efficiency, Ib  0 /hp-hr.

    (2)  Operating transfer efficiency, Ib O^/hp-hr.

    (3)  Horsepower required.

    d. Final Clarifier.  Output (chap 5»  sec  IX).

7-l6.  Example Calculations.

    a. Assume the following  design parameters.

    (1)  K = 0.0072 £/mg-hr at 20°C.

    (2)  a = 0.73.

    (3)  a' = 0.52
                                 7-25

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EM 1110-2-501

Part 1 of 3


   29 Sep 78


    (U)  b = 0.075/day, V = 0.15/day.



    (5^  MLSS = X  = 3000 mg/£.
                 3.


    (6)  I4LVSS = Xy = 2kOO mg/£.



    (7)  F/M = O.UO It BOD/lb MLVSS-day.



    (8)  f = O.ItO.



    (9)  f = 0.53.



   (10)  0 = 1.03.



    "o.  Adjust  K  for temperature.





                             K_ =    Q(T-2°)
                              T    20"


where



     K^ = rate constant at desired temperature



    K   = rate constant at 20°C, 0.0012



      0 = temperature correction coefficient, 1.03



      T = temperature, 15°C for winter conditions




                         Ky = 0.0012(1.03)15~2°




                           1C, = 0.0010£/mg-hr
    c.  Determine size of aeration tank by determining detention time.
                               t =
                                   X^F/M)


where



      t = hydraulic detention time, hr
     S  = influent BOD, 200 mg/£
                                  7-26

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                                                           EM 1110-2-501

                                                             Part  1  of  3


                                                                29 Sep  78
     Xy = MLVSS, 21*00 mg/£



    F/M = food to microorganism ratio, 0.1*0 Ib BOD/lb MLVSS



                               _  2l*(200)

                                 21*00(0.1*0)



                               t = 5.0 hr
    d.  Check detention time for treatability.
                              S  = S e
                               e    o
where
    S  = BOD (soluble) in effluent, 10 mg/£



    S  = BOD  in influent, 200 mg/£



     k = BOD removal rate constant, 0.001 £/mg-hr



    X  = MLVSS, 2 1*00 mg/ 1



     t = detention time, hr



                        10 = 200 e-(0.00l)2>+00(t)




                               t = 1.2^ hr



Therefore use t = 5 • 0 hr



    e.  Calculate volume of aeration tank.





                              V = Qavg + 2h


where



       V = volume, million gal



    Q    = average flow, 1.0 mgd
     avg


       t = detention time, 5.0 hr





                                 7-27

-------
 EM 1110-2-501
 Part  1  of  3
  29 Sep 78
                               V =
                          V = 0.208 million pal

     f.   Calculate oxygen requirements.
where

      0  = oxygen requirement, lb/day

      a' = 0.52

      S^ = BOD removed  (S  - S ) , 190 mg/£

    Q    = average flow, 1.0 mgd

      V = 0.15/day

      Xy = MLVSS, 21*00 mg/£

       V = volume of aeration tank, 0.208 million gal


             02 = 0.52(190)(1.0)8.3U + 0.15(2UOO)(0.208)8.3U


                            02 = lUUQ Ib/day


Check oxygen supplied per Ib BOD removed >1.25.


                       lb 0/lb
where

    0  = oxygen required, ikkQ Ib/day

     Q = flow, 1.0 mgd

    s.  = BOD removed, 190 mg/£




                                  7-28

-------
                      ID 02/lb
                      Ib 0 /Ib BOD  = 0.91 < 1.25
                          2       r
                                                           EM 1110-2-501
                                                             Part  1 of 3
                                                              29  Sep  78

                                          1UU8
therefore

    Ort = 1.25
       = 1.25(Q)(Sr)8.3H

       = 1.25(1.0)(190)8.3U
                              = 1980 Ib 02/day
    g.  Design aeration system (diffused).

    (l)  Assume following parameters.

                 STE =5.0 percent

                   a = 0.9

                   3 = 0.9

                   p = pressure correction factor, 1.0

    (2)  Select summer operating temperature and determine 0  saturation.


                       T = 25°C, (CS)T = 8.2 mg/£

    (3)  Determine operating transfer efficiency.

                              [(Cs) 3P - C ]
                   OTE = STE  t - T9 1?  LJ a(l.02)"~2°

where

      OTE = operating transfer efficiency, percent

      STE = standard transfer efficiency, 5 percent
                                 7-29

-------
EM 1110-2-501
Part 1 of ^
  29 Sep 78

     (CS)T = 8.2 mg/Jl

        6 = 0.9

        p = 1.0

       C  = minimum dissolved oxygen, 2.0 mg/£

        a = 0.9

        T = 25°C

     9-17 = 0  saturation at 20°C
                OTE = 5   -2°^T- 2'01 0.9(1.02)25-20


                            OTE = 2.9 perdent

    (4)  Calculate required airflow.

                                0 (105)7.48
                        R  =
                         a   OTE(0.0176)l44o(V)

where

        R  = required air flow, cfm/1000 ft
         cl

       OTE = operating transfer efficiency, 2.9 percent

         V = volume of basin, 208,000 gal

    0.0176 = lb 02 per ft3 air

      l44o = min per day
           = lb 02/day - 1980
                               1980(10^)7.48
                                       '— ' —
                      a   2.9(0.0176)1440(208,000)


                          R  =96.9 cfm/1000 ft3
                           cL

                                 7-30

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3

                                                               29 Sep 78
    h.  Calculate sludge production.,


      AXV = [a(Sr)Qavg - bXV(V) + Qavg(VSS)f + Qavg(SS ~ ™S)]Q.3±


where

       a = 0.73

      S  = BOD removed, 190 mg/fc

    Q    = average flow, 1.0 mgd
     avg

       b = 0.075/day

      Xy = MLVSS, 21*00 mg/£

       V = volume of aeration tank, 0.208 million gal

     VSS = volatile suspended solids in effluent, 150 mg/£

       f = 0.1*0

      SS = suspended solids, 200 mg/£


         AX  = [0.73(190)1.0 - 0.075(2l*00)(0.208)

                             + 1.0(150)0.1*0 + 1.0(200 - 150)]8.31*


                            AXy = 1762 Ib/day

Check  AX^  solids produced against pounds of BOD removed  (0.5-0.7)-

                     Ib solids _ 	AXV	
                     Ib BOD      S  (Q)8.31*(^ volatile)
                           r      r
where

             AX_  = sludge produced, 1762 Ib/day


                                  7-31

-------
EM 1110-2-501

Part 1 of 3

 29 Sep 78
              S  = S  - S  ,190 mg/£
               Q = average flow , 1.0 mgd



        volatile = 80 percent




                     Ib solids = _ 1762

                      Ib BOD     190(1.0)8.3^(0.8
    i.  Determine nutrient requirements

for nitrogen



        N = 0.123 AX



for phosphorus



        P = 0.026 AX
                      N = 0.123(1762) = 216 Ib/day



                      P = 0.02)46(1762) = U3.3 lb/day



                   N in influent = 30 mg/Jl  (Q    )8.3^



                   N in influent = 250.2 >  2l6 required



                       N needed to be added = none



                   P in influent = 15 mg/&  (Q    ) 8.31*
                                             avg


                   P in influent = 125.1 >  ^3-3  required



                          P to be added = none
 j.   Calculate  sludge  recycle  ratio.
                               Q       X
                                r       a
                              I      X  - X
                               avg    u    a
                                  7-32

-------
                                                           EM 1110-2-501

                                                             Part 1 of 3


                                                                29 Sep 78


where



      Q  = volume of recycle sludge, mgd




     avg = average flow, 1.0 mgd



      X  = MLSS, 3000 mgM
       a


      X  = solids concentration in recycled sludge, 10,000 mg/Ji




                          Qr        3,000
                          1.0   10,000 - 3,000
                              Q  = O.U3 mgd
    k.  Calculate solids retention time.



                                  V(X )8.3U
                                       a

where



    SET = solids retention time, days



      V = volume of aeration tank, 0.208 million gal
     X  = MLSS, 3000 mg/£
      3.
                            = 2202 Ib/day
      a   % volatile   0.8


                            m - 0.208(3000)8.:
                             SRT = 2.k days
    1.  Calculate effluent BOD  .
where
                                  7-33

-------
 EM 1110-2-501
 Part  1  of  3
   29 Sep 78

     (BOD5)eff  =  effluent  BOD  , mg/£

           S   =  soluble BODC, 10 mg/£
            e               j
       (Xy)eff  :=  volatile  solids in effluent, 20 mg/£

           f  =  0.53


                      (BOD5)eff = 10 + 0.8>i(20)0.53


                          (BOD5)eff = 18.9 mg/£


 7-17-   Cost Data..  Appropriate cost data and economic evaluation may be
 found in Chapter 8.

 T-18.   Bibliography.

    a.  American Public Health Association, American Society of Civil
 Engineers, American Water Works Association, and Water Pollution Control
 Federation, "Glossary, Water and Wastevater Control Engineering," 1969.

    b.  American Public Works Association, "Feasibility of Computer
 Control of Wastewater Treatment," Report No. 17090DOY, Dec 1970, U. S.
 Environmental Protection Agency, Washington, D. C.

    c.  American Society of Civil Engineers and the Water Pollution
 Control Federation, "Sewage Treatment Plant Design," Manual of Practice
 No. 8, 1959,  1961, 1967, and 1968,  Water Pollution Control Federation,
 Washington, D.  C.

    d.  Bargman, R. D. and Borgerding,  J., "Characterization of the
Activated Sludge Process," Report No.  R2-73-22H,  Apr 1973, U.  S. Envi-
 ronmental Protection Agency, Washington, D.  C.

    e.  Busch,  A. W., Aerobic Biological Treatment of Wastewaters,
Oligodynamics  Press,  1971.

    f.  Center  for Research, Inc.,  University of  Kansas,  "Oxygen Con-
 sumption in Continuous Biological Culture," Report No.  17050DJS, May
1971, U. S. Environmental Protection  Agency, Washington,  D.  C.

    g.  City  of Austin, Texas, "Design  Guides for Biological Wastewater


                                 7-3)4

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                 29 Sep  78
Treatment Processes," Report No. 11010ESQ, Aug 1971, U.  S.  Environmental
Protection Agency, Washington, D.  C.

    h.  Eckenfelder, W. W., Jr., Industrial Water Pollution Control,
McGraw-Hill, New York, 1966.

    i.  Eckenfelder, W. W., Jr., "General Concepts of Biological Treat-
ment," Manual of Treatment Processes, Vol 1, 19&9, Environmental Science
Services, Inc., Briarcliff Manor, New York.

    j.  Eckenfelder, W. W., Jr., Water Quality Engineering for Practic-
ing Engineers, Barnes and Nobel, New York, 1970.

    k.  Eckenfelder, W. W. Jr., "Activated Sludge and Extended Aera-
tion," Process Design in Water Quality Engineering - New Concepts and
Developments, Vanderbilt University, Nashville, Tenn. , 1971.

    1.  Eckenfelder, W. W., Jr., and Ford, D. L., Water Pollution
Control, Pemberton Press, New York, 1970.

    m.  Eckenfelder, W. W., Jr., and O'Connor, 0. J. , Biological Waste
Treatment, Pergamon Press, New York, 1961.

    n.  Gaudy, A. G., Jr., and Gaudy, E. T., "Biological Concepts for
Design and Operation of the Activated Sludge Process," Report No. 17090-
FQJ, Sep 1971, U. S. Environmental Protection Agency, Washington, D. C.

    o.  Goodman, B. L. , Design Handbook of Wastewater Systems: Domestic,
Industrial,  Commercial, Technomic, Westport, Conn, 1971.

    p.  Goodman, B. L. and Englande, A. J.,  "A Consolidated Approach to
Activated Sludge Process Design," Conference on Toward a Unified Con-
cept of Biological Waste Treatment Design,  5-6 Oct 1972, Atlanta, Ga.

    q.  Lawarence, A. W. and McCarty, P. L., "Unified Basis for Biolog-
ical Treatment Design and Operation," Journal, Sanitary Engineering
Division, American Society of Civil Engineers, Vol 96, SA3, 1970.

    r.  Maier, W. J.,  "Biological Removal  of Colloidal Matter from
Wastewater," Report No. R2-73-1^7, Jun 1973, U. S. Environmental Pro-
tection Agency, Washington, D.  C.

    s.  McKinney, R. E., Microbiology for  Sanitary Engineers, McGraw-
Hill, New York, 1962.


                                 7-35

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 EM 1110-2-501
 Part  1  of  3
   29 Sep 78

    t.   Metcalf  and  Eddy,  Inc., Wastewater  Engineering;  Collection,
 Treatment, and Disposal, McGraw-Hill, New York, 1972.

    u.   Okun, D. A.,  "System of Bio-Precipitation of Organic Matter
 from  Sewage," Sewage  Works Journal. Vol 21, No. 5, 19^9, pp 763-79!+.

    v.   Smith, H. S.,  "Homogeneous Activated Sludge Principles and
 Features of the  Activated Sludge Process," Water and Wastes Engineering
 Vol h,  Jul 1967, pp  1*6-50.                 '	  	*'

    w.   Smith, R. and Eilers, R. G., "A Generalized Computer Model for
 Steady-State Performance of the Activated Sludge Process," F¥QA Report
 No. TWRC-15, Oct 1969, Robert A. Taft Water Research Center, Cincinnati
 Ohio.


    x.  Stensel, H.  D. and Shell, G.  L., "Two Methods of Biological
 Treatment Design," Journal, Water Pollution Control Federation  Vol U6
 Feb 197l|, pp 271-281:           ~	-'

    y.  Stewart, M.  J. , "Activated Sludge System Variations - Specific
Applications," The 15th Ontario Industrial Waste Conference, 9-12 Jun
1968, Niagara Falls, Ontario.

    z.  Toerber, E.  D., "Full Scale Parallel Activated Sludge Process
Evaluation," Report  No. R2-72-065, Nov 1972, U. S.  Environmental Protec-
tion Agency, Washington, D. C.

   aa.  Weston,  R.  F., "Design of Sludge Reaeration Activated Sludge
Systems," Journal, Water Pollution Control Federation  Vol 33  No  7
1961,  pp 7^8-757.                            ~	'        '
                                 7-36

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                                                        EM 1110-2-501
                                                          Part 1 of 3
                                                             " 29 Sep 78
              Section IV.   COMPLETE MIX ACTIVATED SLUDGE
7-19-   Background.

    a.   There has "been much discussion and some confusion  concerning
the definition of complete mix activated sludge.   Nevertheless, any
definition will be arbitrary and many differences of opinion will be
aired.   In this manual it will be  assumed that a complete  mix activated
sludge  is achieved when the oxygen uptake rate is uniform  throughout
all parts of the aeration tank and when sufficient mixing  is provided
to maintain the solids in the aeration tank in suspension.  In complete
mixing, the influent primary clarified wastewater and returned sludge
flow are distributed at various points in the aeration tank (fig. 7-3).
The tank serves to equalize or stabilize variations in flow and waste
strength; it also acts as a diluent  for toxic materials.
  INFLUENT
                 COMPLETE MIX
H=H
                AERATION TANK
                      f
                       SLUDGE RETURN
                                                         EFFLUENT
                                           WASTE
                                                         SLUDGE
               Figure 7-3.  Complete mix activated sludge.
    b.  Organic  loading and oxygen demand are uniform throughout the
aeration tank, and mechanical or diffused aeration is used to completely
mix the mixed liquor.

    c.  References j, k, r, and y in paragraph 7-26 provide good dis-
cussions of the  characteristics of this  process and also contain con-
siderable data on design parameters and  design examples.

7-20.  Input Data.

    a.  Wastewater Flow (Average and Peak).  In case of high variabil-
ity, a statistical distribution should be provided.
                                 7-37

-------
EM 1110-2-501
Part 1 of 3
  29 Sep 78

    b.  Wastevater Strength.

    (l)  BOD  (soluble and total),  mg/A.

    (2)  COD and/or TOG (maximum and minimum),  mg/A.

    (3)  Suspended solids, mg/A.

    (it)  Volatile suspended solids  (VSS),  ing/A.

    (5)  Nonbiodegradable fraction  of VSS, mg/A.

    c.  Other Characterization.

    (1)  PH.

    (2)  Acidity and/or alkalinity,  mg/A.

    (3)  Nitrogen,   mg/A.

    (k)  Phosphorus (total and soluble), mg/A.

    (5)  Oils and greases, mg/A.

    (6)  Heavy metals,  mg/A.

    (T)  Toxic or special characteristics  (e.g., phenols),  mg/£.

    (8)  Temperature,  °F or °C.

    d.   Effluent Quality Requirement's.

    (1)  BOD   ing/A.

    (2)  SS,  mg/A.

    (3)  TKN,  mg/A.

    (It)  P, mg/A.

    (5)  Total nitrogen (TKN + NO  - N), mg/A.
   The  form of nitrogen  should be  specified as to  its biological
  availability  (e.g., NH or Kjeldahl).

                                7-38

-------
    (6)  Settleable solids, mg/i/hr.



7-21.   Design Parameters.



    a.  Reaction rate constants and coefficients.
               Constants



              McKinney



                 K
                  m


                 K
                  s


                 K
                  e


              Eckenfelder



                 k



                 a



                 a'



                 b



                 b1



                 f



                 f
       Range
    b.  F/M =  (0.3-0.6).



    c.  Volumetric  loading  =  50-120.



    d.  t =  (3-6) hr.



    e.  t  =  (3-7)  days.
          s


    f.  MLSS = (3000-6000)  mg/£.



    g.  MLVSS  = 0.7 MLSS  =  (2100-1*200)  mg/Jl.
                                                           EM 1110-2-501

                                                             Part 1 of 3


                                                                 29  Sep 78
    15 /hr at 20°C



  lO.U/hr at 20°C



  0.02/hr at 20°C
0.0007-0.002



     0.73



     0.52



     0.075/day



     0.15 /day



     0.1*0



     0.53
                                  1-39

-------
 EM 1110-2-501

 Part 1 of 3

    29 Sep 78


     h.   Q./Q  =  (0.25-1.0).
          r
     i.   lb  02/lb BOD  ^1.25.



     j.   lb  solids/lb BOD  =  (0.5-0.7).


     k.   0 =  (1.0-1.Oh).



     1.   Efficiency = (>90 percent).


 7-22.  Design Procedure.



     a.   McKinney's Approach.



     (l)  Assume the following design parameters from 7-21.


     (a)  Metabolism constant (K ).
                               m

     (b)  Synthesis factor (K ).
                            s


     (c)  Endogenous respiration factor (K )
                                         e

     (d)  Temperature correction coefficient (0).


     (e)  Hydraulic detention time (t).


     (f)  Solids retention time (t ).



     (2)  Adjust metabolism constant, synthesis factor,  and endogenous
respiration factor for  temperature.



                             K       0(T-20)

                             "T    20

where



     K^ = rate constant at desired temperature  T ,  °C


    K   = rate constant at 20°C


      0 = temperature coefficient


      T = temperature,  °C



    (3)  Determine  size of the  aeration tank.

-------
                                                           EM 1110-2-501

                                                             Part 1 of 3


                                                                 29 Sep  78
                              V = Qavgt/2H




where



       V = volume of tank, million gal



    0    = average flov, mgd
     avg


       t = hydraulic detention time, hr



     (U)  Determine soluble effluent BOD^.



                                     F.
                              Fe '  1 + Kmt



 where



     F   =  soluble  effluent  BOD , mg/£
     e                       ->


     F. =  influent BOD ,  mg/£



     K   =  metabolism constant (15/hr at  20°C)
     m


     t =  hydraulic detention time,  hr
 and check  F  < 10 mg/«- ;  if  Fp > 10 mgA ,  increase  t  and recalcu-

             Q ~~                *~
 late new  F
     (5)  Calculate the MLSS concentration.
                                         M. + M..
                                     K F

                             M  =
                              la   K  + l/2Ut
                                   e        s
                            M  = 0.2K M t  (2k)
                             e       e a s



                                        2kt
                                   T-Ul

-------
 EM 1110-2-501
 Part 1 of 3
   29 Sep  78
                      M   = SS..  x —	 + o.l(M  + M
                       11     11     t           a    e'
 where

       M  = total mass,  mg/£

       M  = living,  active mass,
        3.

       M  = endogenous mass, mg/£

       Mi = inert nonbiodegradable  organic  mass,

      Mii = inert inorganic suspended  solids, mg/£

       KS = synthesis factor, 1/hr  (lO.it/hr at  20°C)

       Fg = effluent BOD , mg/£


       Kg = endogenous respiration  factor,  1/hr (0.02/hr at 20°C)

       t   = solids retention time,  days

      SS.^  = inert  organic SS in influent, mg/£

          = VSS x  percent nonliodegradable  (^D.h VSS for municipal waste)

    SS^  =  inert  inorganic SS fraction in  the influent

and check  MT  against  3000-6000 mg/£; vary  t   or  t  until  M   falls
within desired range.                         s                 ^

    (6)   Check organic  loading against F/M = 0.3-0.6.


                               F/M = -

where


    F/M = food to microorganism ratio

     F  = influent BOD  , mg/£

     M_ = total mass, mg/£

-------
                                                          EM 1110-2-501

                                                            Part 1 of 3

                                                               29 Sep 78
      t  = hydraulic  detention time, hr
If F/M < lower limit,  it  is  possible to  reduce  t   and recalculate

If F/M > upper limit,  increase  t   and recalculate  MT  .


    (7)  Calculate the oxygen requirements.


    (a)  Select the oxygen uptake  rate.   The average  rate  of  oxygen

demand, if the waste load is uniform,  is given  by


                          1 5(F  - F )   lA2(M  + M )
                     dO _      i    e  .   	a     e
                     dt        t
                                                o

where


    dO/dt = average oxygen uptake under uniform flow conditions,


       F  = influent BODC, mgA
        i               ?

       F  = soluble effluent BOD  , mg/£
        e                       ?

        t = hydraulic detention time, hr


       M  = living, active mass, mg/£
        a

       M  = endogenous mass, mg/fc
        e

       t  = solids  retention time, days
        s

 Under conditions  where the load varies, the oxygen uptake is equal to

 the synthesis oxygen  demand plus  the endogenous  respiration oxygen de-

 mand or
                                                   e  a
                         Ib 02/hr = ^ x V x 8.3^
 where


          = peak flow, mgd

-------
 EM 1110-2-501
 Part 1 of 3
   29 Sep 78


     Qavg =  avera§e flow,  mgd

       Ke =  endogenous  respiration factor,  hr  (0.02/hr at  20°C)

     (b)   Check oxygen  supplied per pound of BOD removed >1.2|j.


                          lb  02    lb  02/hr
                         lb BOD     Q(F.  -  F  )B.3h
                              •i-       -L    G

     (8)  Design aeration system and  check horsepower  for  complete mixing
against horsepower required for complete  mixing _>0.1  hp/1000  gal;
select the larger horsepower.


     (a)  Diffused Aeration System.


     !_  Assume the following design parameters.


     ^  Standard transfer efficiency, percent, from manufacturer
(5-8 percent ) .


     b_  02 transfer in waste/0  transfer in water «O.9.

     _c  02 saturation in  waste/Og saturation in water  ssO.9.

     d_  Correction factor  for pressure asi.O.


     2_  Select summer operating temperature (25-30°C)  and determine  (from
standard tables) 0  saturation.


     3_  Adjust standard transfer efficiency to operating conditions.

                          [(CB)T(B)(p) - C ]
                OTE = STE J= - ±j-^ - ^=1 a(l.02)T~2°

where


      OTE = operating transfer efficiency, percent

      STE = standard transfer efficiency,  percent


     (cs)T = 02 saturation at selected summer temperature  T , °C, mg/H

        3 = 02 saturation in waste/0  saturation in water «=0.9

-------
                                                          EM 1110-2-501
                                                            Part 1 of 3
                                                               29 Sep 78
       p = correction factor for pressure «1.0

      C  = minimum dissolved oxygen to be maintained in the basin
       L   > 2.0 mgA

       a = 0 transfer in waste/02 transfer in water ^0.9

       T = temperature,  °C

    lj_  Calculate  required air flow.

                               02(105)(7A8)	
                           \       ft" air/\

where
                                        3
     R  = required air flow, cfm/1000 ft
      a
     0  = oxygen required, Ib/day

    OTE = operating transfer efficiency, percent

      V = volume of basin, gal

     (b)  Mechanical Aeration System.

    !_  Assume the following design parameters.

    a  Standard transfer  efficiency,  Ib/hp-hr  (0 dissolved oxygen,
 20°C, and tap water)(5-8  percent).

    b  0  transfer in waste/02 transfer  in water «0.9-

     c_ 0   saturation in waste/O^  saturation  in water  «O.9.

     d Correction  factor  for  pressure «1.0.

     2 Select  summer operating temperature  (25-30°O, and determine
 (from standard tables)  02 saturation.

     3_ Adjust  standard transfer  efficiency  to operating conditions.

-------
 EM 1110-2-501
 Part  1  of  3

   29  Sep 78
                           [(cs) T(e)p - c
                 OTE = STE ±= -  -  - ^ a(l.02)T~2°
where


      OTE = operating transfer efficiency, Ib 0 /hp-hr


      STE = standard transfer efficiency, Ib 0 /hp-hr


     (Cs),j, = ^2 saturation at selected summer temperature  T , °C, mg/£


        £ = 02 saturation in waste/0  saturation in water «0.9


        p = correction factor for pressure ad.O


       C  = minimum dissolved oxygen to be maintained in the basin
            > 2.0 mg/£


        a = 02 transfer in waste/0  transfer in water %0.9

        T = temperature, °C


    h_  Calculate horsepower requirement.


                                  o2

                     hp =  -      - x 100°
where


     hp = horsepower required/1000 gal


     0  = oxygen required, Ib/day


    OTE = operating transfer efficiency, Ib 0 /hp-hr


      V = volume of basin, gal


    (9)  Calculate sludge production and determine pounds of sludge
wasted per day.

-------
                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                                 29 Sep  78
where


    AIVL = sludge produced, Ib/day



     1VL = total mass, mg/£



      V = volume of aeration tank, million gal



     t  = solids retention time, days
      s


    (10)  Check solids produced per pound of BOD removed.



                                        AM
                       Ib solids	T	

                        Ib BODr  ~ Q(F  - Fe)8.3^


where



    AM  = sludge produced, Ib/day



      Q = flow, mgd



     F. = influent BOD , mg/£



     F  = effluent BOD.., mg/£
      e               5

    (ll)  Calculate sludge recycle ratio.



                              Q      M
where
    Q  = volume of recycled sludge, mgd



     Q = flow, mgd



    M_ = total mass, mg/£



          solids concentration in return sludge, mg/£



          Calculate total effluent BOD .

-------
EM 1110-2-501

Part 1 of 3


  29 Sep  78


where



         Sg = effluent soluble BOD, mg/£



    (SS)    = effluent suspended solids, mg/£



         M  = living mass, mg/£
          3.


         M  = total mass, mg/£



    (13)  Determine nutrient requirements, Ib/day



for nitrogen



                          N = 0.123AMT(or



and phosphorus



                          P = 0.026AMT(or



where



    AM  = sludge produced,  Ib/day



    AX  = sludge produced,  Ib/day



and check against BOD:H:P = 100:5:1



    b.   Eckenfelder's Approach.



    (l)  Assume the following design parameters from paragraph 7-21 when

unknown.



    (a)  BOD removal  rate constant  (k).



    (b)  Fraction of  BOD synthesized (a).



    (c)  Fraction of  BOD oxidized for energy (a1).



    (d)  Endogenous respiration  rate (b  and b1).



    (e)  Mixed liquid suspended  solids (MLSS).



    (f)  Mixed liquid volatile suspended solids (MLVSS).

-------
                                                           EM 1110-2-501
                                                             Part  1  of  3
                                                               29  Sep 78

    (g)  Food-to-microorganism ratio (F/M) .

    (h)  NonModegradable fraction of VSS in influent  (f).

    (i)  Degradable fraction of the MLVSS (f')-

    (j)  Temperature correction coefficient  (0).

    (2)  Adjust rate constant for temperature.

                                     (T-20)
                            KT ~ K200
where

     1C, = rate constant at desired temperature,  °C

    K   = rate constant at 20°C

      0 = temperature correction coefficient

      T = temperature, °C

    (3)  Determine the size of the aeration  tank "by first determining
the detention time  t .
                             t =
                                 (XV)(F/M)
where

      t = hydraulic time, hr

     S  = influent BOD ,  rngA

     X^ = MLVSS, mg/£

    F/M = food-to-microorganism ratio

    (k)  Check detention time for treatability

                             S
                              e _    1

where

-------
 EM 1110-2-501
 Part 1 of 3
   29 Sep 78

     Sg  =  BOD   (soluble)  in effluent, mg/SL

     S   =  BOD   in  influent, mg/£

     k  =  BOD  removal rate constant, £/mg/hr

     Xy  =  MLVSS, mg/£

     t  =  detention time, hr

Solve for   t   and compare with  t  above and select the larger,

     (5)   Calculate the volume of aeration tank.

                             V = Q    x X-
                                  avg   2k
where

       V =  volume, million gal

     Q    =  average daily flow, mgd
     a v g

       t =  detention time, hr

     (6)  Calculate oxygen requirements.


                            dO = a'Sr
                            dt    t        V
or
                   = a'(Sr)(Q   )(8.3U) + b'(Xy)(V)(8.3M
                         r   avg
where

    dO/dt = oxygen uptake rate, mg/£/hr

       a' = fraction of BOD oxidized for energy

       S^ = BOD removed (S  - S ), mg/£

        t = detention time, hr



                                 7-50

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                29 Sep 78

       "b1  = endogenous respiration, 1/hr

       Xy = MLVSS

       0  = oxygen requirement , lb/day

     Q    = average flow rate , mgd
      avg
        V = volume of aeration tank, million gal

and check the oxygen supplied against paragraph 7-21 >1.25
where

    0  = oxygen required, Ib/day

     Q = flow, mgd

    S  - BOD removed, mg/£

    (T)  Design aeration system and check horsepower supply for mixing
against horsepower required for complete mixing _<0.1 hp/1000 gal.

    (a) Diffused Aeration System.

    JL  Assume the following design parameters.

    a_  Standard transfer efficiency, percent, from manufacturer
(5-8 percent ) .

    b_  0  transfer in waste/0  transfer in water «=0.9.

    c_  0  saturation in waste/0  saturation in water «O.9-

    d  Correction factor for pressure «1.0.
    2_  Select summer operating temperature (25-30°C) and determine
    m standard tables) 0  saturation.

    3  Adjust standard transfer efficiency to operating conditions.
                                  7-51

-------
 EM 1110-2-501
 Part  1  of  3

   29 Sep 78
                           [(Cs)T(3)(p) - C  ]
                 OTE = STE - i-    - ±- a(l.02)T-20
where

      OTE = operating transfer efficiency, percent

      STE = standard transfer efficiency, percent

     (cs)T ~ 02 saturation at selected summer temperature T, °C, mg/H

        3 = 02 saturation in waste/0  saturation in water *0.9

        p = correction factor for pressure ssd.O

       C  = minimum dissolved oxygen to be maintained in the basin
            > 2.0 mg/J>

        a = 02 transfer in waste/0  transfer in water =»0.9

        T = temperature, °C

    k_  Calculate required air flow.
                R  =
                           /        Ib 0-  \ /       .
                     (OTE)  0.0176 - —2-    141*0  ^  V
                           \        ft3 air/ V
where

     R  = required air flow, cfm/1000 ft
      cl

     02 = required oxygen, Ib/day

    OTE = operating transfer efficiency, percent

      V = volume of basin, gal

    (b) Mechanical Aeration System.

    !_  Assume the following design parameters.

    a  Standard transfer efficiency,  Ib/hp-hr (0 dissolved oxygen,  20°C,
and tap water) (5-8 percent).

                                 7-52

-------
                                                           EM 1110-2-501

                                                             Part 1 of 3


                                                                29 Sep 78
    "b  0  transfer in waste /O  transfer in water *0.9-
        d                    d


    c  0^ saturation in waste/00 saturation in water «O.9.
    —   d                      d


    d_  Correction factor for pressure ssl.O.



    2_  Select summer operating temperature (25-30°C) and determine

(from standard tables) 0  saturation.



    _3_  Adjust standard transfer efficiency to operating conditions.



                          [(CsU0)(p) -
                OTE - STE - ±~~  -   a(l.02)
where
      OTE = operating transfer efficiency, Ib 0 /hp-hr



      STE = standard transfer efficiency, Ib 0 /hp-hr



    (Cs)  = 0  saturation at selected summer temperature  T , °C, mg/£



        3=0  saturation in waste/0  saturation in water wO.9



        p = correction factor for pressure «L.O



       C  = minimum dissolved oxygen to be maintained in the basin

            > 2.0 mg/£



        a, = 0  transfer in waste/0  transfer in water



        T = temperature , °C



    k_  Calculate horsepower requirement.






                     hp = -    2 - x 100°
where



     hp = horsepower required/1000 gal
     0  = oxygen required, Ib/day
                                  7-53

-------
EM 1110-2-501

Part 1 of 3


  29 Sep 78



    OTE = operating transfer efficiency, Ib 0 /hp-hr



      V = volume of basin, gal



    (8)  Calculate sludge production.
                            bXyV + fQ(VSS) + Q(SS.-



where




     AX  = sludge produced, Ib/day



       a = fraction of BOD removed synthesized to cell material



      S  = BOD removed, rag/ Si



    Q    = average flow, mgd
     avg


       b = endogenous respiration rate/day



      Xy = MLVSS, mg/£



       V = volume of basin, gal



       f = noribiodegradable fraction of influent VSS



       Q = flow, mgd



     VSS = volatile suspended solids in effluent, mg/£



      SS = suspended solids in influent, mg/£



    (9)  Calculate solids produced per pound of BOD  removed and check

AX   against value given in paragraph 7-21 .
  V
                                         AY
                         Ib solids         V
                         (Ib BODr)   Sr(Q)(8.3*0
where
    AX  = sludge produced, Ib/day



     S  = BOD removed, mg/&

-------
                                                           EM 1110-2-501

                                                             Part 1 of 3


                                                                29 Sep 78


      Q = flow, mgd



    (10)  Calculate sludge recycle ratio.



                              Q      X
                               r      a
                              Q    X  - X
                                    u    a
where
    Q /Q = sludge recycle ratio
     r


      Q  = volume of recycled sludge, mgd



       Q = flow, mgd



      X  = MLSS, mg/Jl
       a


      X  = solids concentration in return sludge, mg/&



    (ll)  Calculate solids retention time.



                                  (V)X (8.310

                            SET = -
                                      AX

where
    SET = solids retention time, days
                            AX  =
                              a   % volatile
    (12)  Calculate effluent BOD .
                           eff -Se + 0.8MXv)
where
         S  = effluent soluble BOD, mg/£
          e


    (xv) ** - effluent volatile suspended solids, mg/£
      v eff


         f = degradable fraction of MLVSS



    (13)  Determine nutrient requirements, Ib/day
                                 7-55

-------
EM 1110-2-501
Part 1 of 3
  29  Sep  78

for nitrogen

                          N = 0.123AMT(or

and phosphorus

                          P = 0.026AMT(or

where

    AM  = sludge produced, lb/day

    AX  = sludge produced, lb/day

and check against BOD:N:P = 100:5:1.

7-23-   Output Data.

    a.  Aeration Tank.

    (l)  Reaction rate constant, £/mg/hr.

    (2)  Sludge produced per BOD removed,

    (3)  Endogenous respiration rate ("b, b').

    (k)  Op utilized per BOD removed.

    (5)  Influent nonbiodegrada'ble VSS (f).

    (6)  Effluent degradable VSS (f').

    (7)  lb BCD/lb MLSS-day (F/M ratio).

    (8)  Mixed liquor SS, mg/Jl (MLSS).

    (9)  Mixed liquor VSS, mg/£ (MLVSS).

   (10)  Aeration time, hr.

   (ll)  Volume of aeration tank, million gal.

   (12)  Oxygen required, Ib/day.


                                  7-56

-------
                                                          EM 1110-2-501

                                                            Part 1 of 3

                                                                29 Sep 78
   (13)  Sludge produced, Ib/day.



   (ik)  Nitrogen requirement, Ib/day.



   (15)  Phosphorus requirement, Ib/day.



   (16)  Sludge recycle ratio, percent.



   (IT)  Solids retention time, days.



   b.  Diffused Aeration System.



   (l)   Standard transfer efficiency, percent.



   (2)   Operating transfer efficiency, percent.



   (3)   Required air  flow, cfm/1000  ft3.



   c.  Mechanical Aeration System.



    (1)   Standard transfer efficiency,  Ib  02/hp-hr.



    (2)   Operating transfer efficiency,  Ib 02/hp-hr.



    (3)   Horsepower  required.



7-2U.   Example Calculations,  Eckenfelder's Approach.



   a.  Assume the  following  design parameters.



    (1)   k = 0.0012  £/mg-hr.



    (2)   a = 0.73.



    (3)   a' = 0.5-



    (10   b = 0.075/day, b'  =  0.15/day.



    (5)   MLSS = X  = 3000 mg/A.
                 Si


    (6)   MLVSS = Xy = 2^00 mg/&.



    (7)   F/M = 0.1*0 Ib BOD/lb MLVSS-day.
                                  7-57

-------
EM 1110-2-501
Part 1 of 3
  29 Sep  78

    (8)  f = o.Uo.

    (9)  f = 0.53.

   (10)  0 = 1.03.

    b.   Adjust the BOD removal rate constant for winter conditions,
T = 15°C.

                             K       eT~20
                              T    20"
where

     IL = rate constant at temperature  T

    Kg  = rate constant at 20°C, 0.0012 £/mg-hr

      T = temperature, 15°C

      0 = temperature correction coefficient, 1.03


                         K.J, = 0.0012(1.03)15~2°

                          KL, = 0.0010 £/me-hr
    c.  Determine size of aeration tank by determining detention time.
                                   24 S
                              t =

where

      t = hydraulic detention time, hr

     S  = influent BOD, 200 mg/£

     Xy = MLVSS, 2*100 mg/£

    F/M = food-to-microorganism ratio, O.hO Ib BOD/lb MLVSS

                               =  2^(200)
                                 2^00(0.
                                 7-58

-------
                               t = 5.0 hr


    d.  Check detention time for treatability.



                             S
                             SQ   1 +


where


    S  = effluent BOD.- (soluble), 10 mg/£
     e               5


    S  = influent BOD.., 200 mg/£
     o               P

     K = BOD removal rate constant, 0.001 &/mg/hr



    X  = MLVSS, 2UOO mg/£



     t = detention time, hr
                         10
                        200   1 + (O.OOl)2UOO(t)


                          t = 7.9 hr > 3.0 hr



    e.  Calculate the volume of the aeration tank.




                              V =


where


       V = volume , million gal


    Q    = average flow,  1.0 mgd
     avg

       t = detention time, 7-9 hr
                           V =  0.329 million  gal



     f.   Calculate  oxygen requirements.





                                  7-59
                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                               29  Sep 78

-------
EM 1110-2-501

Part 1  of  3


   29 Sep 78
                      °2  =
where



       0  = oxygen required,  Ib/day



       a' = 0.52



     Sr = BOD removed  (S  -  S  ) ,  190 mg/&



    Q    = average flow , 1.0 mgd



       b' = 0.15/day



       Xy = MLVSS, 2UOO mg/£



       V = volume of aeration tank, 0.329 million  gal




             02 = 0.52(190)1. 0(8. 3U) +  0.15(2UOO)0. 329(8. 3U)




                             02 =  1812 Ib/day




Check  oxygen supplied per lb BOD  removed >1.25.
                           "i T. TJ f~^Ti    f*\ f o  ^ Q
                           XD riUJJ    wl D  )o.
                                 r      r

where



    0  = oxygen required, 1812 Ib/day



     Q = average flow, 1.0 mgd
    S  = BOD removed, 190 mg/£
                             °2        1812
                         lb BOD    1.0(190)8.3^
                       lb 02/lb BOD  = l.lU < 1.25
Therefore




                                 T-60

-------
                                                           EM 1110-2-501


                                                             Part  1 of 3

                                                              29 Sep 78
    0  = 1.25 BODr
       = 1.25
                 L



       = 1.25(1.0)190(8.3M




                            00 = 1980 Ib/day
    g.  Design aeration system (mechanical surface).




    (l)  Assume the following parameters,




                  STE =5.0 percent




                    a = 0.9




                    3 = 0.9




                    p = pressure correction factor,  1.0




    (2)  Select summer operating temperature and determine 0  saturation,





                        T = 25°C, (CS)T =  8.2 mg/£





    (3)  Determine operating transfer efficiency.





                          [(CsL(e)(p) - C ]

                OTE = STE 	      	i1- a(l.02)

                                 y • -L I


where




      OTE = operating transfer efficiency, percent




      STE = standard transfer efficiency,  5.0 percent




    (CS)T = 8.2 mg/£




       C  = minimum dissolved oxygen,  2.0  mg/£
        L
        T = 25°C    a = 0.9    3 = 0.9








                                  7-61
9-17 = 0  saturation at 20°C

-------
 EM 1110-2-501
 Part  1  of  3
 29 Sep  78  "


              OTE = 5.0  [8.2(0.9)1 0 - 2.01 0.9(l.02)25-20
                                y • -i-1

                         OTE = 2,9% or Ib 02/hp-hr


    (^)  Calculate horsepower requirements.



                             hp ~ OTE(2MV
where

     hp = horsepower requirements, hp/1000 gal

     02 = oxygen required, 1980 Ib/day

    OTE = operating transfer efficiency, 2.9 percent

      V = volume of aeration tank,  0.329 million gal

                        ,  = 	1980	
                         P   2.9(2100. 329(1000)

                hp = 0.09 hp/1000 gal < 0.1 hp/1000 gal

Therefore use  hp = 0.1 hp/1000 gal

                             hp = 0.1(V)1000

                           hp = 0.1(0.329)1000

                        hp = 32.9 hp (use 35 hp)

    h.  Calculate sludge production.
                                   avg
where

     AX^ = sludge produced, Ib/day

       a = 0.73


                                 7-62
                       - bXy(V)  + Qay(VSS)f + Qav(SS - VSS)]8.3U

-------
                                                          EM 1110-2-501
                                                            Part 1 of 3
                                                              29 Sep  78

     S  = BOD removed, 190 mg/£
      r
        =1.0 mgd
     avg
      b = 0.075 May

     Xy = 2^00 mg/A

      V = 0.329 million  gal

     VSS = effluent volatile  suspended  solids, 150 mg/£

      f = O.UO

     SS = suspended  solids in  influent,  200 mg/£

            AX^ =  [0.73(190)1.0 -  0. 075(2^00)0.329

                                +  1. 0(150)0. UO + 1.0(200  -  150)]8.3U

                           AX  =  1580  Ib/day                    (
i.  Calculate solids produced per pound of BOD  removed and check
> 0.5-0.7-

                                        V
                            Ib solids _
                             Ib BOD     SrQ8.3i

where

    AX_  = solids produced, 1580 Ib/day

     S  = BOD removed (S  - S ), 190 mg/i
      r                 o    e
      Q = average flow, 1.0 mgd


                        Ib solids =     1580
                         Ib BOD     190(1. 0)8.
                               r
                 Ib solids/lb BOD  = 1.0 > 0.5-0.7 (OK)
                                 7-63

-------
 EM 1110-2-501

 Part  1  of  3


  29 Sep 78


    j.   Calculate  sludge recycle ratio.
                                     X
                                      a
                              Q    X  - X
                                    u    a



where



    Qr = volume of recycled sludge, mgd



     Q = average flow, 1.0 mgd



    X  = MLSS, 3000 mg/£
     Si


    X^ = return sludge concentration, 10,000 mg/£



                           Q
                            r  _    3,000

                           1.0   10,000-3,000
                             Qr = 0.^29 mgd
    k.  Calculate solids retention time.

                                  V(X )8.

                            SRT = —
                                       a

where



    SRT = solids retention time, days



      V = volume of aeration tank, 0.329 million gal



     X  = MLSS, 3000 mg/£
      8-


                volatile = 1580/0. 80 = 1975 Ib/day




                              _ 0.329(3000)8.3^
                              --    -
                             SRT = k.2 days
    1.   Calculate effluent BOD
                                 7-6k

-------
                                                           EM 1110-2-501

                                                             Part 1 of 3


                                                               29 Sep 78


                     (BOD5)eff = Se + 0.8MXV)efff


where


    (BOD5)    = effluent BOD  , mg/£


           S  = effluent soluble BOD  , 10 mg/&
            e                       5

       (Xv)    = effluent volatile suspended solids,  20 mg/SL


           f = 0.53


                     (BOD5)    = 10 + 0.8U(20)0.53



                           (BOD5)eff = 19 mg/£



    m.  Determine nutrient requirement


 for nitrogen


                               N =  0.123AXV


                               N =  0.123(1580)


                               N =  19U lb/day


 for phosphorus


                              P =  0.026AX


                              P =  0.026(1580)


                              P =  ill Ib/day


 N in  influent = 30
                          av


               = 30(1. 0)8. 3^


               = 250 Ib/day > 19^ l"b/day required


                           N to be added = none
 P in influent = 15 mg/2,(Qavg)8.
                                  7-65

-------
 EM 1110-2-501
 Part 1 of 3
  29 Sep 78

               = 15(1.0)8.3U

               = 125 Ib/day > kl Ib/day required

                           P_to_be_ added - _none_

 7-25.   Cpst Data.   Appropriate cost data arid economic evaluation may be
 found in Chapter 8.

 7-26.   Bibliography.

     a.   American Public  Health Association,  American Society of Civil
 Engineers,  American  Water  Works Association,  and Water Pollution Control
 Federation,  "Glossary, Water and Wastewater  Control  Engineering," 1969.

     b.   American Public  Works  Association,  "Feasibility of  Computer
 Control of  Wastewater Treatment," Report  No.  17090DOY,  Dec  1970,  U.  S.
 Environmental  Protection Agency,  Washington,  D.  C.

     c.   American Society of  Civil Engineers  and  the  Water Pollution
 Control Federation,  "Sewage  Treatment  Plant  Design," Manual of  Practice
 No.  8,  1959, 1961, 1967, and 1968,  Water  Pollution Control  Federation
 Washington, D.  C.

     d.   Bargman, R. D. and Borgerding, J., "Characterization  of the
 Activated Sludge Process," Report  No.  R2-73-22U, Apr 1973,  U. S.  Envi-
 ronmental Protection  Agency, Washington,  D. C.

     e.   Burkhead, C.  E., "Evaluation,of CMAS Design  Constants," Confer-
 ence on  Toward  a Unified Concept  of Biological Waste  Treatment  Design
 5-6  Oct  1972, Atlanta, Ga.

     f.   Burkhead, C.  E.  and McKirmey, R.  E., "Application of  Complete-
Mixing Activated Sludge Design Equations to Industrial Wastes," Journal,
Water Pollution Control Federation. Vol 1*0, Apr -1968, pp 557-570~*"

    g.  Busch, A. W., Aerobic Biological Treatment of Wastewaters,
Oligodynamics Press, 1971.

    h.  Center for Research, Inc., University of Kansas, "Oxygen  Con-
sumption in Continuous Biological Culture," Report No. 17050DJS, May
1971, U. S.  Environmental Protection Agency,  Washington, D.  C.

    i.  City of Austin,  Texas, "Design Guides for Biological Wastewater


                                  7-66

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep  78

Treatment Processes," Report No.  11010ESQ, Aug 1971, U.  S.  Environmental
Protection Agency, Washington, D.  C.

    j.   "Design and Operation of Complete Mixing Activated Sludge
Systems," Environmental Pollution Control Service Reports, Vol 1, No 3,
Jul 1970.

    k.   Eckenfelder, W. W., Jr., Industrial Water Pollution Control,
McGraw-Hill, New York, 1966.

    1.   Eckenfelder, W. W., Jr., "General Concepts of Biological Treat-
ment," Manual^of Treatment Processes, Vol 1, 1969, Environmental Science
Services, Inc., Briarcliff Manor, New York.

    m.   Eckenfelder, W. W., Jr., Water Quality Engineering for Practic-
ing Engineers, Barnes and Nobel, New York, 1970.

    n.   Eckenfelder, W. W., Jr., "Activated Sludge and Extended Aera-
tion," Process Design in Water Quality Engineering - New Concepts and
Developments, 1971, Vanderbilt University, Nashville, Tenn.

     o.   Eckenfelder, W. W., Jr., and Ford, D.  L. , Water Pollution
Control,  Pemberton  Press, New York, 1970.

     p.   Eckenfelder, W. W., Jr., and O'Connor, 0. J. , Biological Waste
Treatment,  Pergamon Press,  New York, 1961.

     q.   Gaudy, A.  G.,  Jr.,  and Gaudy, E.  T. ,  "Biological  Concepts  for
Design  and  Operation of the Activated Sludge  Process," Report  No.  17090-
FQJ, Sep 1971, U.  S. Environmental Protection Agency, Washington,  D.  C.

     r.   Goodman,  B.  L. , Design Handbook  of Wastewater Systems:   Domestic,
 Industrial, Commercial, Technomic, Westport,  Conn.,  1971.

     s.   Goodman,  B.  L.  and Englande, A.  J.,  Jr., "A Consolidated
Approach to Activated  Sludge  Process Design," Conference  on  Toward a
Unified Concept  of Biological Waste  Treatment Design,  5-6 Oct  1972,
Atlanta, Ga.

     t.   Lawrence, A. W.  and McCarty, P.  L.,  "Unified Basis for Biologi-
 cal Treatment Design and  Operation," Journal, Sanitary  Engineering
 Division, American Society of Civil  Engineers, Vol  96,  SA3,  1970.

     u.   Maier, W. J.,  "Biological Removal of Colloidal  Matter from


                                  7-67

-------
  EM  1110-2-501
  Part 1 of  3

  29 Sep 78

 Wastewater," Report No. R2-73-l>*7, Jun 1973, U. S. Environmental Protec-
 tion Agency, Washington, D. C.


 Q1 /'  „ TMcKinney> R- E., "Mathematics of Complete-Mixing Activated
 bludge,  Journal, Sanitary Engineering Division, American Society of
 Civil Engineers, SA3. Mav 1Q£P3 rr 87-113.        	~*	


     w.   McKinney, R. E., Microbiology for Sanitary Engineers  McGraw-
 Hill,  New York, 1962.	

     x.   McKinney, R. E. and Ooter, R. J., "Concepts of Complete Mixing
 Activated Sludge," Bulletin No. 60, 1969, Transactions of the I9th
 Annual  Conference on Sanitary Engineering, University of Kansas  Law-
 rence,  Kans.                                                    '


     y.   Metcalf and Eddy, Inc., Wastewater Engineering: Collection.
 -treatment,  and  Disposal.  McGraw-Hill, New York, 1972.           "	

     z.   Okun, D.  A., "System of Bio-Precipitation  of  Organic Matter
 from Sewage,  Sewage Works  Journal. Vol 21,  No. 5, 191*9,  pp  763-791*.

   aa.   Smith,  H.  S.,  "Homogeneous Activated Sludge and Principles and
 Features  of the Activated Sludge Process," Water and Wastes  Engineering.
 \'ol  U, Jul  1967,  PP  1*6-50.                 ~~	"—'	&	fi-*


   bb.  Smith,  R.  and  Eilers,  R.  G.,  "A Generalized Computer Model for

 N^jifrep**6 n6^?™^0^  °f the Activated  Sludge Process," FWQA Report
                               A-  Taft Water  Research Center,  Cincinnati,
   cc.  Stensel, H. D. and Shell, G. L. ,  "Two Methods of Biological
Treatment Design,  Journal, Water Pollution Control Federation  Vol 1*6
Feb 197k, PP 271-283.          '            ~	~~	


   dd.  Stewart, M. J., "Activated Sludge System Variations - Specific
Applications,   The 15th Ontario Industrial Waste Conference, 9-12 Jun
1968, Niagara Falls, Ontario.


   ee.  Toerber, E. D., "Full Scale Parallel Activated Sludge Process
Evaluation,'   Report No.  R2-72-065, Nov 1972, U. S. Environmental
Protection Agency, Washington, D. C.

   ff.  Weston, R.  F., "Design of Sludge Reaeration Activated Sludge
Systems," Journal, Water Pollution Control Federation  Vol 33  No  7
1961, pp 748-757.~~~'

-------
                                                          EM 1110-2-501
                                                            Part  1  of  3
                                                              29 Sep 78
               Section V.   STEP AERATION ACTIVATED  SLUDGE
7-27-  Background.

    a.  Step aeration is defined as "a procedure for adding increments
of settled wastewater along the line of flov in the aeration tanks of
an activated sludge plant" (para 7-3^a).   It is a modification of the
activated sludge process in which an attempt is made to equalize the
food-to-microorganism ratio (F/M).  The first application of this
process was at the Talljnans Island plant in New York City in 1939-

    b.  Baffles are used to split the aeration tank into four (or more)
parallel channels.  Each of these channels is a separate step and all
channels are linked together in series (fig. 7-M •

       INFLUENT


— fc
1
1
U
AERATION TANK
SL
.UDGE
RETURN
/C-TT, mr\ EFFLUENT
V TANK /
+ vyASTE

-*
               Figure 7-U.  Step aeration activated sludge.

     c.   Flexibility  of  operation is a prime factor to consider in the
 design  of  the process.  The oxygen demand is essentially uniform over
 the length of the basin, resulting in more efficient utilization of the,
 oxygen  supplied.  Introduction  of influent waste at multiple locations
 and return of a highly  absorptive sludge floe permit this process to
 remove  soluble organics within  a relatively short contact time; there-
 fore,  it is characterized  by  higher volumetric  loadings than the con-
 ventional  plug flow  activated sludge process.

     d.   References c, t, v, and y in paragraph  7-3^ discuss the step
 aeration modification and  enumerate the design  parameters.

 7-28.   Input Data.

     a.   Wastewater Flow (Average and Peak).   In case  of high variability,
 a statistical distribution should be provided.
                                   7-69

-------
EM 1110-2-501
Part 1 of 3
29  Sep  78

    "b-  Wastewater Strength.

    (1)   BOD^ (soluble and total),  rng/fc.

    (2)   COD and/or TOC (maximum and minimum),  mg/£.

    (3)   Suspended solids, mg/H.

    (k)   Volatile suspended solids  (VSS),  mg/£.

    (5)   Nonbiodegradable  fraction  of VSS, mg/Ji.

    c.   Other Characterization.

    (1)   pH.

    (2)   Acidity  and/or alkalinity,  mg/£.

    (3)   Nitrogen,  mg/£.

    (^)   Phosphorus  (total and soluble), mg/£.

    (5)   Oils  and greases,  mg/£.

    (6)   Heavy rnetals , mg/£.

    (7)   Toxic or special  characteristics  (e.g., phenols), mg/£.

    (8)   Temperature,  °F or °C.

    d.   Effluent Quality Requirements.

    (1)   BOD5, mg/4.

    (2)   SS, ing/A.

    (3)   TKN, mg/A.

    (U)   P, mg/Jl.
  The form of nitrogen should be specified as to its biological
   availability (e.g., NH  or Kjeldahl).
                                7-TO

-------
                        EM 1110-2-501

                          Part  1 of  3



                            29  Sep 78
    (5)   Total nitrogen (TKN + NO^N),  mg/£.



    (6)   Settleable solids, mg/A/hr.



7_29.  Design Parameters.



    a.  Reaction Rate Constants and Coefficients.



                Constants                  	.
                Range
               McKinney



                  K
                   m


                  K
                   s


                  K
                   e


               Eckenfelder



                  k



                  a



                  a'



                  b



                  V



                  f



                  f



     to.  F/M = (0.2-0.10.



     c.  Volumetric  loading = 40-60.



     d.  t = (3-5) hr.



     e.  t  = (3-7)  days.
          s


     f.  MLSS = (2000-3500)
           15/hr at 20°C



         lO.U/hr at 20°C



         0.02/hr at 20°C







         0.0007-0.002 Jl/mg/hr



         0.73



         0.52



         0.075/day



         0.15/day



         O.i*0



         0.53
7-71

-------
 EM 1110-2-501

 Part  1 of •=!

 29 Sep 78


    g.   MLVSS =  (1400-2450)



    h.   Qr/Q  - (0.25-0.75).


    i.   Ib  00/lb BOD   >_ 1.25.



    j.   Ib  solids/lb BOD  =  (0.5-0,7).



    k.   0 = (1.0-1.04).



    1.   Efficiency = (>90 percent).



 7-30.   Design Procedure.



    a.   McKinney's Approach.



    (l)   Assume the following design parameters.


    (a)   Metabolism constant (K ).
                               m


    (b)   Synthesis factor (K ).
                            o


    (c)   Endogenous respiration factor (K ).
                                         e


    (d)   Temperature correction coefficient (0).



    (e)   Hydraulic detention time (t).



    (2)  Adjust the metabolism constant,  the synthesis factor, and the

endogenous rate of respiration for temperature.




                            K       Q(T-2°)
                             T    20"



where



     K^ = rate constant at desired temperature,  T ,  °C



    K   = rate constant at 20°C



      0 = temperature coefficient



      T = temperature,  °C.




                                 7-72

-------
                                                           EM 1110-2-501

                                                             Part 1 of 3


                                                               29 Sep 78


    (3) Determine size of the aeration tank.



                                      /t \
                              V = Q   (•^Tj



where


       V = volume of tank, million gal



    Q    = average flow, mgd
     avg


       t = hydraulic detention time, hr



    (1+)  Determine soluble effluent BOD .


                                     F.
                              Fe = 1 + Kmt


where


    F  = soluble effluent BOD-, mg/X,
     e                       ?


    F. = influent BOD5, mg/X,



    K  = metabolism constant (15/hr at 20°C)
     m

     t = hydraulic detention time, hr



and check  F  £ 10 mg/X,  .  If  F  > 10 ,  increase  t   and  calculate

new  F


    (5)  Calculate the MLSS concentration and check total  mass  against

2000-3500 mg/£.
                                        M.  + M..
                                  K F

                         M  =
                          a " K  + I/2h t
                         M  =  0.2K M t (2k)
                          e       e a sv   '
                                  7-73

-------
 EM 1110-2-501

 Part 1 of 3


 29 Sep 78
                      M.  = SS.  — s
                       i      i\. t



                                  2kt



                     Mii  = SSii X— T


 vhere




      Hp = total mass,  mg/£




      M  = living active  mass,  mg/£
       QI



      Mg = endogenous mass,  mg/£




      IYL  = inert nonbiodegradable organic  mass,  mg/£




    M^^^^ = inert inorganic  suspended solids,  mg/£




      Kg = synthesis  factor, 1/hr (10 -  Vhr  at  20°C)




      Kg = endogenous respiration factor,  1/hr  (0.02/hr  at  20°c)




      "t   = solids  retention time, days




    SS^  = inert organic  SS in  influent, mg/Ji




         = VSS x percent  nonbiodegradable




   SSii  =  inert inorganic SS fraction in  the influent




    (6)   Check organic loading against 0.2-0.4.
where




    F/M = food-to-microorganism ratio




     F± = influent BOD , mg/£




     I^L = total mass, mg/£




      t = detention time, hr

-------
                                                           m 1110-2-501
                                                             Part  1  of  3
                                                                29 Sep 78

If F/M < lower limit, it is possible to reduce  t   and recalculate  MT  .
If F/M > upper limit, increase  t  and recalculate  MT .

    (7)  Calculate the oxygen requirements.

    (a)  Select oxygen uptake rate.   The average rate of  oxygen  demand,
if the waste load is uniform, is given by
dO
dt
~1.5(Fi - Fe)~
t
-
"i.U;
a
M )"
e
2H
s
where

    dO
    dt
= average oxygen uptake rate,  mg/£/hr,  under uniform flow
         conditions
    F. = influent BOD , mg/£

    F  = effluent BOD,-, mg/£

     t = detention time, hr

    M  = living mass, mg/£
     a
    M  = endogenous mass, mg/£

    t  = solids retention time, hr
     s
Under conditions where the load varies, the oxygen uptake is equal to
the synthesis oxygen demand plus the endogenous respiration oxygen
demand or
                dO
                dt
                      "0.5(F. - F
                                      avg,
                                     + l.lUK M
                                            e a
where
       P
  = peak flow, mgd

  - average flow, mgd
      K  = endogenous respiration factor/hr
                                 7-75

-------
 EM 1110-2-501
 Part 1 of 3

 29 Sep 78


     (b)   Supply oxygen  for peak hourly  load.
where


     02 = oxygen required, Ib/hr

     dO _
     dt - average oxygen uptake rate, mg/£/hr, under uniform flow
         conditions


     V = volume of the tank, gal


and  check oxygen supplied per Ib of BOD removed >1.25


                       lb 0
                      Ib

where


    02 = oxygen required, Ib/hr


     Q = flow, mgd


    FI = influent BOD , mg/£


    Fg = effluent BOD , mg/£


    (8)  Design aeration system and check horsepower supply for mixing
against horsepower required for mixing >0.1 hp/1000 gal.


    (a)  Diffused Aeration System.


    !_  Assume the following design parameters.


    _a  Standard transfer efficiency,  percent,  from manufacturer
(5-8 percent).


    b_  02 transfer in waste/02 transfer in water ^0.9.


    £  02 saturation in waste/02 saturation in water 3=0.9.
                                 1-16

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29  Sep  78
    d_  Correction factor for pressure «1.0.
    2_  Select summer operating temperature (25-30°C)  and determine
(from standard tables)  0^ saturation.

    3_  Adjust standard  transfer efficiency to operating conditions.
                           s) (6)(p) -
              OTE = STE -- - ^-     -   ad.02)
where

      OTE = operating transfer efficiency, percent

      STE = standard transfer efficiency, percent

    (C )  =0  saturation at selected summer temperature  T  , °C,

        3=0  saturation in waste/0  saturation in water ssO.9

        p = correction factor for pressure szL.O

       C  = minimum dissolved oxygen to be maintained in the basin
        L   > 2.0 mg/£

        a = 0  transfer in waste/0  transfer in water «£>.9

        T = temperature, °C

    h  Calculate required air flow.

                                0
                 R  = 	
                  a
                       (OTE)0.0176         -uUo       V
                                   \ft   air/ v
 where
                                         •?
     R  =  required air  flow,  cfm/1000 ft
       a
      0  = oxygen required,  Ib/day
                                  7-77

-------
EM 1110-2-501
Part 1 of  ^
  29 Sep 78

    OTE =  operating transfer efficiency, percent

      V =  volume of basin, gal

    (b)  Mechanical Aeration System.

    !_  Assume the following design parameters.

    a.  Standard transfer efficiency, Ib/hp-hr  (0 dissolved oxygen,
20°C, and  tap water).

    b_  0_  transfer in waste/0? transfer in water «s0.9.

    c_  Qg  saturation in waste/0  saturation in water «0.9.

    d_  Correction factor for pressure al.O.

    _2_  Select summer operating temperature (25-30°C) and determine
(from standard tables) 0? saturation.

    3_  Adjust standard transfer efficiency to operating conditions
               OTE = STE  = -      - i a(l.02)i~c:U
                                y • -L I

where

      OTE = operating transfer efficiency, Ib 0 /hp-hr

      STE = standard transfer efficiency, Ib 0 /hp-hr

       \  = 0  saturation at selected summer temperature  T , °C, mg/£

        3 = 0  saturation in waste/0  saturation in water a=o.9

        p = correction factor for pressure «1.0

       C  = minimum dissolved oxygen to be maintained in the basin
            > 2.0
        a = 02 transfer in waste/0  transfer in water ssO.9


                                  T-T8

-------
                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                                29 Sep 78
    T = temperature, °C



    k_  Calculate horsepower requirement.
                                  - x 100°
where



     hp = horsepower req.uired/1000 gal



     Op = oxygen required, l"b/day



    OTE = operating transfer efficiency, l"b 0 /hp-hr



      V = volume of basin, gal



    (9)  Calculate sludge production and determine amount of sludge

wasted per day.
where



    AM^ = sludge produced, Ib/day



     ML = total mass, mg/£



      V = volume of aeration tank, million gal



     t  = solids retention time, days
      S


    (10)  Check solids produced per pound of BOD removed.




                   f'lb solids\       AMT

                     Ib BOD   I  Q(F. - F
                           1C /     1    t



where



    AM_ = sludge produced, Ib/day





                                 1-19

-------
EM 1110-2-501

Part 1 of 3

 29 Sep  78



      Q = flow, mgd



     F. = influent BOD , mg/J,



     F  = effluent BODC, mg/Jl
      e               p


    (ll)  Calculate sludge recycle ratio.



                              Qr__    HT


                                    ii   "^^

where



    Q  = volume of recycled sludge, mgd



     Q = flow, mgd



    M  = total mass, mg/£



    M  = solids concentration in return sludge, mg/£
     u


    (12)  Calculate total effluent BOD.
                (BOD^
'M \

 ~^ (0.76)
                      'eff    "



where



       S  =  effluent  soluble BODC, mg/«,
        e                       p


     SS    =  suspended solids in effluent,



       M  =  living mass, mg/£
        3,


       IVL =  total mass, mg/£



     (13)  Determine nutrient requirements for nitrogen





                           N =  0.123AMT(or



 and phosphorus
                                  7-80

-------
                                                           EM 1110-2-501
                                                             Part  1 of 3
                                                               29  Sep 78

                          P = 0.026AMT(or M^)

where

    AM^ = sludge produced, Ib/day

    AM  = sludge produced, Ib/day

and check against BOD:N:P = 100:5:1.

    b.  Eckenfelder's Approach.

    (l)  Assume the following design parameters when unknown.

    (a)  BOD removal rate constant (k).

    (b)  Fraction of BOD synthesized (a).

    (c)  Fraction of BOD oxidized for energy (a1).

    (d)  Endogenous respiration rate (b and b')«

    (e)  Mixed liquor suspended solids (MLSS).

    (f)  Mixed liquor volatile suspended solids (MLVSS).

    (g)  Food-to-microorganism ratio (F/M).

    (h)  Temperature correction coefficient (0).

    (i)  Nonbiodegradable fraction of VSS in influent (f).

    (j)  Degradable fraction of the MLVSS (f).

    (2)  Adjust BOD removal rate constant for temperature.


                                    (T-20)
                           KT - K209

where

     K  = rate constant for desired temperature, °C
    K   = rate constant at 20°C
                                 7-81

-------
 EM 1110-2-501
 Part 1 of 3
  29 Sep 78


       Q = temperature  correction  coefficient

       T = temperature,  °C


     (3)   Determine  size of the aeration tank by first determining the
 detention time.
                             t =
                                  (XV)(F/M)


where


      t = detention time, hr

     S  = influent BOD, mg/£

     Xy = MLVSS, mg/£


    F/M = food-to-microorganism ratio

    (M  Check detention time for treatability.


                             S
                              e _     1
                             S    1 + kX.rt
                              o         v
where


    Sg = BOD  soluble in effluent, mg/£

    SQ = BOD  in influent, mg/£

     k = BOD removal rate constant, £/mg/hr

    Xy = MLVSS, mg/£

     t = detention time, hr


and solve for  t  and compare with  t  in (3)  above and select the
larger.


    (5)   Calculate the volume of aeration tank.
                                 7-82

-------
                             v =


where


       V = volume, million gal


    Q    = average daily flow, mgd


       t = detention time, hr


    (6)  Calculate oxygen requirements.
                          dt
                  = a'(Sr)(Qavg)(8.3lO
or






where



      -r— = oxygen uptake rate, mg/£/hr
      dt


      a1 = fraction of BOD oxidized for energy



      S  = BOD removed (S  - S )
       r                 o    e


       t = detention time, hr



      V = endogenous respiration rate, £/hr



      Xy = MLVSS



      Op = oxygen requirement, lb/day



    Q    = average flow rate, mgd
     avg


       V = volume of aeration tank, million gal



and check the oxygen supplied against 5*L.25.



                                         0^
                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                               29 Sep 78
                                 7-83

-------
EM 1110-2-501
Part 1 of ^
 29  Sep 78

where

    0  = oxygen required, l"b/day

     Q = flow, mgd

    S  = BOD removed, mg/£

    (7)  Design aeration system.

    (a)  Diffused Aeration System.

    _L  Assume the following design parameters.

    a_  Standard transfer efficiency, percent, from manufacturer
(5-8 percent ) ,

    b_  0  transfer in waste/0  transfer in water %0.9.

    c_  0  saturation in waste/0  saturation in water ȣ).9.

    d_  Correction factor for pressure sal.O.

    2_  Select summer operating temperature (25-30°C) and determine
(from standard tables) 0  saturation.

    J3  Adjust standard transfer efficiency to operating conditions.
                       |~(CS) (B)(p) - C "I
                       •*= - ^     - ^
             OTE = STE                        .


where

      OTE = operating transfer efficiency, percent

      STE = standard transfer efficiency, percent

    (Cs)  = Op saturation at selected summer  temperature T,  °C , mg/£

        B = 00 saturation in waste/0? saturation in water ssO.9

        p = correction factor for pressure ^L.O



                                 7-81+

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
       C  = minimum dissolved oxygen to be maintained in the basin
        L'   > 2.0 mg/A

        T = temperature,  °C

        a = 0  transfer in waste/0  transfer in water «0.9

    U  Calculate required air flow.
                R  =
                 a
                     (OTE)0.0176ft3
where

     R  = required air flow, cfm/1000 ft
      9,
     Op = oxygen required, Ib/day

    OTE = operating transfer efficiency, percent

      V = volume of basin, gal

    (b)  Mechanical Aeration System.

    I_  Assume the following design parameters.

    a.  Standard transfer efficiency, Ib/hp-hr (0 dissolved oxygen,
20°C, and tap water).

    b  Q0 transfer in waste/0  transfer in water ssO.9.

    c  0  saturation in waste/0  saturation in water «0.9-

    d_  Correction factor for pressure «1.0.

    2_  Select summer operating temperature (25-30°C) and determine
(from standard tables) 0  saturation.

    3  Adjust standard transfer efficiency to operating conditions.
                                 7-85

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EM 1110-2-501
Part 1 of 3

 29 Sep 78
                         |~(cs) (e)(P) - c "I
               OTE = STE L	T    1T	i* a(l.02)T~20
where
      OTE = operating transfer efficiency, Ib 0 /hp-hr


      STE = standard transfer efficiency, Ib 0 /hp-hr


    (Cs)  = 0^ saturation at selected summer temperature T, °C, mg/Jl


        3 = 0  saturation in waste/0  saturation in water «0.9


        p = correction factor for pressure «1.0


       C  = minimum dissolved oxygen to be maintained in the basin
            > 2.0 mg/£


        a = 0,3 transfer in waste/0  transfer in water ssO.9


        T = temperature, °C


    *4  Calculate horsepower requirement.



                    hp = - - -- -  x 1000
where


     hp = horsepower required/1000 gal


     0  = oxgen required, Ib/day


   OTE  = operating transfer efficiency, Ib 0 /hp-hr


      V = volume of basin, gal


    (8)  Calculate sludge production.
                         - bXy(v) + fQ(VSS) + Q(SS -
where

-------
                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                                29  Sep 78
     AX^ = sludge produced, Ib/day



       a = fraction of BOD removed synthesized to cell material



      S  = BOD removed, mg/£



    Q    = average flow, mgd
     avg


       b = endogenous respiration rate, I/day



      Xy. = volatile solids in raw waste, mg/£



       V = volume of tank, gal



       f = nonbiodegradable fraction of influent VSS



       Q = flow, mgd



     VSS = volatile suspended solids in effluent, mg/fc



      SS = suspended solids in influent, mg/£



    (9)  Check  AX   against 0.5-0.7.
                        Ib/solids        AXV




where
                        (Ib BODr)
    AX^ = sludge produced, Ib/day



     S  = BOD removed, mg/£



      Q = flow, mgd



    (10)  Calculate sludge recycle ratio.
                                    Xa
                              Q   X  - X
                                   u    a

where




    Q  = volume of recycled sludge, mgd



     Q = flow, mgd




                                 7-87

-------
EM 1110-2-501

Part 1 of 3

29 Sep 78



    X  = MLSS, mg/£
     cl



    Xu = susPend-e(i solids concentration in returned sludge, mg/£



    (ll)  Calculate solids retention time.



                                (V)(X X8.310

                         SET = —   a
                                    AX
                                      a
where



    SRT = solids retention time, days



      V = volume of basin, gal



     X  = MLSS, mg/£
      €L
    AX  = T^	
      a   % volatile


    AX  = sludge produced, Ib/day
      a


    AXy = sludge produced, Ib/day



    (12)  Calculate effluent BOD .
                  /BOD,.\    = S^ + 0.8MVSS)^(f)
where
        S  = effluent soluble BOD , mg/£
    VSS    = effluent volatile suspended solids, mg/£



        f '  = degradable fraction of MLVSS



    (13)  Determine nutrient requirements



for nitrogen



                        N = 0.123AMT (or




                                 T-88

-------
                                                           EM 1110-2-501
                                                             Part  1 of 3
                                                                29 Sep 78
and phosphorus

                        P = 0.026AMT (or

where

        = sludge produced, Ib/day

        = sludge produced, It/day

and check against BOD:N:P = 100:5:1.

7-31.  Output Data.

    a.  Aeration Tank.

    (l)  Reaction rate constant, Jl/mg/hr.

    (2)  Sludge produced per BOD removed.

    (3)  Endogenous respiration rate (b, b').

    (10  0  utilized per BOD removed.

    (5)  Influent nonbiodegradable BSS  (f).

    (6)  Effluent degradable VSS (f1).

    (7)  Ib BOD/lb MLSS-day  (F/M ratio).

    (8)  Mixed liquor SS, mg/£  (MLSS).

    (9)  Mixed liquor VSS, mg/£  (MLVSS).

    (10)  Aeration time,  hr.

    (11)  Volume  of aeration  tank, million  gal.

    (12)  Oxygen  required,  Ib/day.

    (13)  Sludge  produced,  Ib/day.

         Nitrogen  requirement,  Ib/day.



                                  7-89

-------
EM 1110-2-501
Part 1 of 3
  29 Sep 78

    (15)  Phosphorus requirement, Ib/day.

    (l6)  Sludge recycle ratio, percent.

    (IT)  Solids retention time, days.

    b.   Diffused Aeration System.

    (l)  Standard transfer efficiency,  percent.

    (2)  Operating transfer efficiency, percent.

    (3)  Required air flow, cfm/1000 ft .

    c .   Mechanical Aeration System.

    (l)  Standard transfer efficiency,  Ib  0?/hp-hr.

    (2)  Operating transfer efficiency, Ib 0 /hp-hr.

    (3)  Horsepower required.

7-32.  Example Calculations.   The design procedure for a step aeration
activated sludge system is the same  as  that for  a complete mix activated
sludge system.  Example calculations are shown in paragraph 7-2^,  and
therefore will not be repeated here.

7-33-  Cost Data.  Appropriate cost  data and economic  evaluation may be
found in Chapter 8.

7-3^-  Bibliography.

    a.   American Public Health Association, American  Society of Civil
Engineers,  American Water Works Association, and Water Pollution Control
Federation, "Glossary, Water and Wastewater Control Engineering,"
    b.  American Public Works Association,  "Feasibility of Computer
Control of Wastewater Treatment," Report lo.  17090DOY,  Dec 1970,  U. S.
Environmental Protection Agency, Washington,  D.  C.

    c.  American Society of Civil Engineers and  the Water Pollution
Control Federation, "Sewage Treatment Plant Design," Manual of Practice
Wo. 8, 1959, 1961, 1967, and 1968, Water Pollution  Control Federation,
Washington, D. C.


                                 7-90

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3

                                                              29 Sep  78

    d.  Bargman, R. D. and Borgerding, J., "Characterization of the
Activated Sludge Process," Report No. R2-T3-22^, Apr 1973, U. S.  Envi-
ronmental Protection Agency, Washington, D. C.

    e.  Busch, A. W., Aerobic Biological Treatment of Waste-waters,
Oligodynamics Press, 1971-

    f.  Center for Research, Inc., University of Kansas, "Oxygen
Consumption in Continuous Biological Culture,"  Report No.  17050DJS,
May 1971, U. S. Environmental Protection Agency, Washington, D.  C.

    g.  City of Austin, Texas, "Design Guides for Biological Waste-water
Treatment Processes," Report No.  1101OESQ, Aug  1971, U. S. Environmental
Protection Agency, Washington, D. C.

    h.  Eckenfelder, W. W., Jr.,  Industrial Water Pollution Control,
McGraw-Hill, New York, 1966.

    i.  Eckenfelder, W. W., Jr.,  "General Concepts of Biological Treat-
ment," Manual of Treatment Processes, Vol 1, 1969, Environmental Science
Services, Inc., Briarcliff Manor, New York.

    j.  Eckenfelder, W. W., Jr.,  Water Quality Engineering for Practicing
Engineers, Barnes and Nobel, New York, 1970.

    k.  Eckenfelder, W. W., Jr.,  "Activated Sludge and Extended Aeration,"
Process Design in Water Quality Engineering - New Concepts and Develop-
ments, 1971, Vanderldlt University, Nashville,  Tenn.

    1.  Eckenfelder, W. W., Jr.,  and Ford, D. L., Water Pollution Control,
Pemberton Press, New York, 1970.

    m.  Eckenfelder, W. W., Jr.,  and O'Connor,  0. J., Biological Waste
Treatment, Pergamon Press, New York, 1961.

    n.  Gaudy, A. G., Jr., and Gaudy, E. T., "Biological Concepts for
Design and Operation of the Activated Sludge Process," Report No.
17090-FQJ, Sep 1971, U. S. Environmental Protection Agency, Washington,
D. C.

    o.  Goodman, B. L. , Design Handbook of Wastewater Systems:  Domestic,
Industrial, Commerical, Technomic, Westport, Conn., 1971•
                                 7-91

-------
 EM 1110-2-501
 Part  1  of  3
  29 Sep 78

    p.   Goodman, B. L. and Englande, A. J., Jr., "A Consolidated
 Approach to Activated Sludge Process Design," Conference on Toward a
 Unified Concept of Biological Waste Treatment Design, 5-6 Oct 1972,
 Atlanta, Ga.

    q.   Lawrence, A. W. and McCarty, P. L. , "Unified Basis for Bio-
 logical Treatment Design and Operation," Journal. Sanitary Engineering
 Division,  American Society of Civil Engineers. Vol 96. SA3. 1970'.

    r.   Maier, W. J., "Biological Removal  of Colloidal Matter from
 Wastewater," Report No. R2-73-lVf, Jun 1973, U. S. Environmental
 Protection Agency, Washington, D. C.

    s.  McKinney, R. E., Microbiology for  Sanitary Engineers, McGraw-
 Hill, New  York, 1962.                                 	

    t.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection,
 Treatment, and Disposal^ McGraw-Hill, New York, 1972.

    u.  Okun, D. A., "System of Bio-Precipitation of Organic Matter
 from Sewage," Sewage Works Journal» Vol 21, No. 5, 19^9, pp 763-79^.

    v.  Smith, H.  S., "Homogeneous Activated Sludge and Principles and
 Features of the Activated Sludge Process," Water and Wastes Engineering
 Vol k, Jul 1967, pp >*6-50.                 	  	"

    w.  Smith, R.  and Eilers, R. G. , "A Generalized Computer Model for
 Steady-State Performance of the Activated Sludge Process," FWQA Report
 No. TWRC-15, Oct 1969, Robert A. Taft Water Research Center, Cincinnati,
 Ohio.

    x.  Stensel, H.  D. and Shell, G. L., "Two Methods  of Biological
 Treatment Design," Journal, Water Pollution Control Federation,  Vol U6,
 Feb 197^, PP 271-283"]

    y.  Stewart, M.  J., "Activated Sludge System Variations - Specific
Applications," The 15th Ontario Industrial Waste Conference, 9-12 Jun
 1968,  Niagara Falls, Ontario.

    z.  Toerber, E.  D., "Full Scale Parallel Activated Sludge Process
Evaluation," Report  No.  R2-72-065, Nov 1972, U.  S.  Environmental Pro-
tection Agency, Washington, D.  C.
                                 7-92

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                                                          EM 1110-2-501
                                                            Part  1  of  3
                                                               29  Sep 78

    aa.   Weston,  R.  F.,  "Design of Sludge Reaeration Activated  Sludge
Systems," Journal, Water Pollution Control Federation,  Vol 33,  No. 7,
1961, pp 7W-757-
                                  7-93               (next page is 7-95.

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                                                           EM  1110-2-501
                                                            Part  1  of  3
                                                               29 Sep 78
             Section VI.   EXTENDED AERATION ACTIVATED  SLUDGE
7-35.  Background.
    a.  The extended aeration process is defined as  "a modification of
the activated sludge process which provides for aerobic sludge  digestion
within the aeration system.   The concept envisages the stabilization of
organic matter under aerobic conditions and disposal of the end products
into the air as gases and with the plant effluent as finely divided sus-
pended matter and soluble matter" (para 7-li2a).  The process operates
in the endogenous respiration phase which requires a relatively small
F/M ratio and long detention time.  In the process,  the aeration deten-
tion time is determined by the time required to oxidize the solids  pro-
duced by synthesis from the BOD removed.  The accumulation of volatile
solids is very low and approaches the theoretical minimum; however,
since some of the biological solids are inert, an accumulation  of solids
occurs in the system.  Sludge storage facilities should be provided;
most states make it a requirement.  The flow chart  for the extended
aeration process is identical to that for plug flow  (fig.  7-5)-
INFLUENT ^
A
— w
L
AERATION TANK
SLUDGE RETURN
[SETTLING^ EFFLUENT ^
\ TANK J
^T
T WASTE ^
SLUDGE '
                 Figure 7-5-  Plug flow activated sludge.

    b.  Process design parameters and excellent design examples are
found in References c, h, o, u, w, and z in paragraph 7-U2.

7-36.  Input Data.

    a.  Wastewater Flow (Average and Peak).  In case of high variability.
a statistical distribution should be provided.

    b.  Wastewater Strength.

    (1)  BOD  (soluble and total), mg/£.

    (2)  COD and/or TOG (maximum and minimum), mg/£.
                                 7-95

-------
 EM 1110-2-501
 Part  1  of  3

 29 Sep 78

     (3)  Suspended  solids, mg/£.

     (h)  Volatile suspended  solids  (VSS),  ing/8,.

     (5)  Nonbiodegradable fraction  of  VSS, mg/£.

    c.  Other Characterization.

     (1)  PH.

     (2)  Acidity and/or alkalinity, mg/Jl.

     (3)  Nitrogen,  mg/Jl.

     (H)  Phosphorus (total and soluble), mg/Jl.

    (5)  Oils and greases, mg/Jl.

    (6)  Heavy metals, mg/£.

    (T)  Toxic or special characteristics  (e.g., phenols), mg/Jl.

    (8)  Temperature, °F or °C.

    d.  Effluent Quality Requirements.

    (1)  BOD5, mg/A.

    (2)  SS, ng/A.

    (3)  TKN, ing/£.

    (U)  P, mg/Jl.

T-37.   Design Parameters.

    a.  Reaction rate constants.
   The form of nitrogen should be specified as to its biological
  availability (e.g., NH  or KJeldahl).
                                  7-96

-------
                                                        EM 1110-2-501

                                                          Part 1 of 3


                                                             29 Sep 78
             Constants



            McKinney



                K
                 m


                K
                 s


                K
                 e


            Eckenfelder



                k



                a



                a'



                b



                b'




                ao


                f



                f'



b.  F/M = (0.05-0.15).



c.  Volumetric  loading = 10-25,



d.  t - (18-36)  hr.



e.  t  = (20-30) days.
     S


f.  MLSS =  (3000-6000) mg/£.



g.  MLVSS =  (2100-U200) mg/£.



h.  Qr/Q =  (0.75-1.5).



i.  Ib 0 /ITa BOD  >_ 1.5.
       Range
  15/hr at 20°C



10A/hr at 20°C



0.02/hr at 20°C







0.0007-0.002 £/mg/hr



0.73



0.52



0.075/day



0.15/day



0.77a = 0.56



0.1+0



0.53
                             7-97

-------
 EM 1110-2-501

 Part 1 of 3

  29 Sep 78


     j.   Ib solids/lb BOD  < 0.2.
                         r —


     k.   0 = (1.0-1.03).


     1.   Efficiency = (>90 percent).


 7-38.   Design Procedure.



     a.   McKinney's Approach.



     (l)   Assume the following design parameters.


     (a)   Metabolism constant (K  ).
                               m

     (b)   Synthesis factor  (K ).
                            s


     (c)   Endogenous  respiration factor  (K  ).
                                         e

     (d)   Temperature correction coefficient (0).


     (e)   Hydraulic  detention time (t), min.


     (f)   Solids retention time (t ), days.
                                 S


     (2)  Adjust the metobolism constant, synthesis factor, and endog-

enous rate of respiration for temperature.




                             K  = K  e^T~2°)


where



     K^ = rate constant at desired temperature


    K   = rate constant at 20°C


      6 = temperature coefficient


      T = temperature,  °C



    (3)   Determine the  size of the aeration tank.



                             V =  0
                                 7-

-------
                                                           EM 1110-2-501

                                                             Part  1  of  3


                                                                 29 Sep  78


where



       V = volume of tank, million gal



    Q   . = average flow, mgd
     avg


       t = hydraulic detention time, hr



         Determine soluble effluent BOD .



                                     F.
                              F  = 	±	

                               e   1 + K t
                                        m
where
    F  = soluble effluent BOD , mg/£



    F. = influent BOD   mg/£



    K  = metabolism constant, 15/hr at 20°C



and check  F  >_ 10 mg/£ ; if  F  > 10 mg/£  increase  t  and calculate

new  F  .                       e
      e


    (5)  Calculate the MLSS concentration and check  M   against

3000-6000 mg/£.                                        T




                     Mm=M  +M  + M. + M..
                      I1    a    e    i    ii
                                          11
                            K F

                     M  = 	*-£
                     M  = 0.2K'M t (2i|)
                      e       e a s
                     M.  = SS.  x
                      .      .
                      lit
                     M. .  = SS. .  x —-S- + o.l (M  + M )
                      11      11     t         x  a    e'
                                 1-99

-------
 EM  1110-2-501

 Part 1  of  3


 29 Sep 78



 where




      M_ = total mass, mg/£




      M = living active mass, mg/£
        cl



      M = endogenous mass, mg/Jl




      1YL = inert nonModegradable organic mass, mg/£




     M   = inert inorganic suspended solids, mg/£




      K = synthesis factor, 1/hr (lO.U/hr at 20°C)
        s



      K^ = endogenous respiration factor, 1/hr (0.02/hr at 20°C)



      t  = solids retention time, days
        S



     SS^ = inert organic suspended solids in influent




         = VSS x % nonModegradable (O.h x VSS for municipal waste)




    SSii = inert inorganic suspended solids fraction in the influent




    (6)  Check organic loading against 0.05-0.15.
where




    F/M = food-to-microorganism ratio



     Fi = influent BOD , mg/£



     M™ = total mass, mg/£




      t = retention time, min




If  F/M < lower limit, it is possible to reduce  t  and recalculate

MT .


If  F/M > upper limit, increase  t  and recalculate  M




    (T)  Calculate the oxygen requirements.




                                 T-100

-------
                                                           EM 1110-2-501

                                                             Part 1 of 3


                                                               29 Sep 78
    (a)  Select the oxygen uptake rate.   The average rate of oxygen

demand, if the waste load is uniform,  is given "by




                   dO   ^(Fi - Fe}   1A2(\ + V
                   dt        t             2kt
                                              s
where
    dO/dt = average oxygen uptake rate, mg/£/hr, under uniform flow

            conditions



       F. = influent BOD , mg/£



       F  = effluent BOD._, mg/£
        e               5


        t = detention time, days



       M  = living mass, mg/£
        El


       M  = endogenous mass, mg/£



       t  = solids retention time, days
        s


Under conditions where the load varies, the oxygen uptake is equal to

the synthesis oxygen demand plus the endogenous respiration oxygen

demand or
                  dt        *       VW
                  °2 = dt X V X 8'3k

where



      Q  = peak flow, mgd



    Q    = average flow, mgd
     avg
      K  = endogenous respiration factor, 1/hr
       e


      GO = oxygen required, Ib/hr



       V = volume of "basin, gal
                                 7-101

-------
 EM 1110-2-501
 Part 1 of 3
  29 Sep 78

     (b)  Check oxygen supplied per pound of BOD removed >_ 1.5.
                                     i  - Fe)(8.3U)


     (8)  Design  aeration  system and check horsepower supply for
 complete mixing  against horsepower  required for complete mixing
 >_ 0.1 hp/1000  gal.


     (a)  Diffused aeration  system.

     !_  Assume  the following design  parameters.

     a_  Standard  transfer  efficiency, percent,  from manufacturer
 (5-8 percent).


     b_  02 transfer in waste/0   transfer in water asO.9.

     c_  02 saturation in waste/02 saturation in  water s£>.9.

     d_  Correction factor  for pressure sal.O.

    2_  Select  summer operating  temperature (25-30°C)  and determine
 (from standard tables) 0  saturation.


    3_  Adjust  standard transfer efficiency to operating  conditions.


                                        -  Cl

                OTE - STE	^y^	=± a(l.02)T-20


where

      OTE = operating transfer efficiency,  percent

      STE = standard transfer efficiency,  percent


    (Cs)   = °2 saturation at selected summer temperature  T  ,   °C , mg/£

        3 = 02 saturation in waste/02 saturation in water «£.9.

        p = correction factor for pressure saL.O.

                                 7-102

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                                                          EM 1110-2-501

                                                            Part 1 of  3

                                                               29 Sep 78
       C  = minimum  dissolved  oxygen to be maintained  in  the basin

       L  > 2.0 mgA



       a = 0  transfer  in waste/0  saturation  in water «€>.9



       T = temperature,  °C



       Calculate required air  flow.
                R  =
                 a
                           \       ftj air/x




where



     R  = required air flow, cfm/1000 ft
      a


     0  = oxygen required, Ib/day



    OTE = operating transfer efficiency, percent



      V = volume of basin, gal



     (b)  Mechanical aeration system.



    !_  Assume the following design parameters.



    a  Standard transfer  efficiency,  Ib/hp-hr  (0 dissolved oxygen,

 20°C, and tap water).



    b_  0  transfer  in waste/02 transfer  in water «0.9-



     c_  0  saturation in waste/Og  saturation  in water aO.9.



     d_  Correction factor  for pressure «1.0.



     2_  Select  summer operating temperature  (25-30°O and determine

 (from  standard tables)  02 saturation.



     3  Adjust  standard  transfer  efficiency  to operating conditions.
                                  7-103

-------
 EM 1110-2-501
 Part 1 of 3
  29  Sep 78
F(cs) (B)(p) - CL!
± - *_ -
                 OTE = STE ± - *_ - -  a(l.02)T-2°
                                  y • J- 1

 where


       OTE = operating transfer  efficiency,  Ib 0 /hp-hr

       STE = standard transfer efficiency, Ib  0 /hp-hr


     (Cs)   = °2  saturati°n at selected summer  temperature T,  °C, mg/£

         3 = 02  saturation in waste/02 saturation in water «0.9

        p = correction factor for  pressure  ssl.O


        C   = minimum dissolved oxygen  to be  maintained  in the basin
             > 2.0 mg/£
        a = 02  transfer in waste/Og transfer  in water  ^0.9

        T = temperature,  °C


     k_  Calculate horsepower requirement.


                                   Op

                     hp =  -       - x  100°
where


     hp = horsepower required/1000 gal


     02 = oxygen required, Ib/day


    OTE = operating transfer efficiency, Ib 0 /hp-hr


      V = volume of basin, gal


    (9)  Calculate sludge production and determine pounds of sludge
wasted per day.

                                  MV(8.3M
                            AMm =  x
                              T      t

-------
                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                                29 Sep 78
where


    AMj^ = sludge produced, Ib/day


     Mr^ = total mass, mg/£


      V = volume of aeration tank, million gal



     t  = solids retention time, days
      s

    (10)  Check solids produced per pounds of BOD removed.




                      Ib solids _ 	_T	

                       Ib BOD     Q(F. - F )(8.3^)
                             r       i    e



    (11)  Calculate sludge recycle ratio.



                               Q      M,,
                                       T
where
    M  = solids concentration in return sludge, mg/A
     u

    (12)  Calculate total effluent BOD .



                                            /M

                (BOD5) = Se + (0.8U)(SS)eff I ^(0.76)
where
         S  = effluent soluble BOD^, mg/H
          e                       5


     (SS)    = suspended solids in effluent, mg/£



         M  = living mass, mg/&
          a


         MT = MLSS, mg/£



     b.   Eckenfelder's Approach.



     (l)  Assume the following design parameters when known.




                                 7-105

-------
 EM 1110-2-501
 Part  1  of  3
 29 Sep  78
     (a)  Fraction of BOD synthesized  (a).
     (b)  Fraction of BOD oxidized for energy (a1).
     (c)  Endogenous respiration rate  (b and b1).
     (d)  Fraction of BOD  synthesized to degradable solids (a ).
                        2                                    o
     (e)  Nonbiodegradable fraction to VSS in influent (f).
     (f)  Mixed liquor suspended solids (MLSS).
     (g)  Volatile solids in mixed liquor suspended solids (MLVSS)
    (h)  Temperature correction coefficient (0).
    (i)  Degradable fraction of the MLVSS (f).
    (j)  Food-to-microorganism ratio (F/M).
    (k)  Effluent soluble BODr (S ).
                             5   e
    (2)  Adjust the BOD removal rate constant  for temperature.

                             K  = K  0(T~20)
where
     KT = rate constant for  desired temperature
    K   = rate constant at 20°C
      0 - temperature  correction coefficient
      T = temperature,  °C
    (3)   Determine  the  size  of the  aeration tank.
                              a  (S   -  S  )Q
                          V =            ^
                                (xv)(f)(b)
                                7-106

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                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                               29 Sep 78
where


       V = aeration tank volume, million gal


      a  = fraction of BOD.- synthesized to degradable solids
       o                  5

      S  = influent BOD , mg/£


      S  = effluent soluble BOD , mg/£
       e                       5

    Q    = waste flow, mgd
     avg

      Xy = MLVSS, mg/£


      f = degradable fraction of the MLVSS


       b - endogenous respiration rate, I/day


    (h)  Calculate the detention time.
where


    t = detention time, hr


    V = volume, million gal


    Q = flow, mgd


    (5)  Assume the organic loading and calculate detention time.
                                     T M


where


      t = detention time, days



     S  = influent BOD  , mg/£





                                7-107

-------
 EM 1110-2-501
 Part 1 of 3
  29 Sep 78

      Xy = volatile solids in raw sludge,  mg/£


     F/M = organic  loading (food-to-microorganism ratio)

 and select the larger of two detention times  from (It)  or (5).

     (6)  Determine the oxygen requirements  allowing 60 percent for
 nitrification during  summer.
       °  = a'S8'l  + b'l   +  0.6(1*.
        2


where


      0  = oxygen required, Ib/day

      a' = fraction of BOD oxidized for energy

      S^ = BOD  removed, mg/£

    Q    = average waste flow, mgd

      "b1 = endogenous respiration rate, I/day

      Xy = MLVSS, mg/£


       V = aeration tank volume, million gal

     TKN = total Kjeldahl nitrogen, mg/&

and calculate oxygen requirement (>1.5)


                         lb 0          0
where


    0  = oxygen, required, Ib/day

     Q = waste flow, mgd

    S  = BOD  removed, mg/£
                                7-108

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                 29 Sep 78

    (7)  Design aeration system and check horsepower supply for complete
mixing against horsepower required for complete mixing >_0.1 hp/1000 gal.

    (a)  Diffused aeration system.

    !_  Assume the following design parameters.

    a_  Standard transfer efficiency, percent, from manufacturer
(5-8 percent).

    b  0^ transfer in waste/00 transfer in water «O.9-
    —   2                    c.
    c_  0  saturation in waste/0  saturation in water =0.9-

    d  Correction factor for pressure %1.0.
    2  Select summer operating temperature (25-30°C) and determine
    m standard tables) 0  saturation.

    3_  Adjust standard transfer efficiency to operating conditions.
                OTE = STE J-	* . .„	- a(l.02)T 2°
                                 y« ->-1
where

      OTE = operating transfer efficiency, percent

      STE = standard transfer efficiency, percent

    (C \  =0  saturation at selected summer temperature T, °C, mg/£
    V S/rj-i    2
        B = 0  saturation in waste/0  saturation in water =^0.9

        p = correction factor for pressure a£L.O

       C  = minimum dissolved oxygen to be maintained in the basin
            > 2.0 mg/H

        a = 0  transfer in waste/0  transfer in water «O.9

        T = temperature, °C

    k_  Calculate required air flow.

                                 7-109

-------
EM 1110-2-501

Part 1 of 3


 29 Sep 78
                R  =
                 a         /        Ib 0  \ .       . .

                     (OTE) [0.0176 —-—— \llkhO ^-JV
                           \        .pj.3  .   A     day/
                           \       ft  air/


where



     R  = required air flow, cfm/1000 ft
      Q,


     0  = oxygen required, lb/day



    OTE = operating transfer efficiency, percent



      V = volume of basin, gal



    (b)  Mechanical aeration system.



    !_  Assume the following design parameters.



    a_  Standard transfer efficiency, lb/hp-hr  (0 dissolved oxygen,  20°C,

and tap water).



    b  0  transfer in waste/0  transfer in water asO.9-
        d                    d


    c  00 saturation in waste/00 saturation in water «=0.9.
    —   c.                      c.


    d_  Correction factor for pressure »1.0.



    2_  Select summer operating temperature (25-30°C) and  determine  (from

standard tables) 0^ saturation.



    3_  Adjust standard transfer efficiency to  operating conditions.


                          |7c ) (e)(P) - c I

                               T1            I        T—PD
                OTE = STE	 „ .^	 a(l.02)
where
OTE = operating transfer efficiency, Ib 0 /hp-hr



STE = standard transfer efficiency, Ib 0 /hp-hr



 \  = 0  saturation at selected summer temperature T, °C, mg/£
 /'ri    C-
      S/rji
                                T-110

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
        g = 0  saturation in waste/0  saturation in water =0.9

        p = correction factor for pressure ssl.O

       C  = minimum dissolved oxygen to be maintained in the basin
        L
            > 2.0 mg/£
        a = 0  transfer in waste/0? transfer in water ==0.9

        T = temperature, °C

       Calculate horsepower requirement.
                     hp =
                           OTEhFh?
where

     hp = horsepower required/1000 gal

     0  = oxygen required, Ib/day

    OTE = operating transfer efficiency, Ib 02/hp-hr

      V = volume of basin, gal

    5_  Calculate sludge production.
  AXy = 8.3Ma(Sr)(Q) - (b)(Xv)(V) - Q(SSeff) + Q(VSS)f + Q(SS - VSS)]


where

       A)L = volatile sludge produced, Ib/day

         a = fraction of BOD synthesized

        S  = BOD  removed, mg/£

         Q = waste flow, mgd

         b = endogenous respiration rate, I/day


                                7-111

-------
EM 1110-2-501

Part 1 of 3


  29  Sep  78



        Xy = volatile solids in raw sludge, mg/£



         V = aeration tank volume, million gal



     SSeff = effluent suspended solids, ing/i



       VSS = volatile suspended solids in influent, mg/£



        f' = degradable fraction of the MLVSS



       VSS = volatile suspended solids, mg/£



    6_  Calculate solids produced per pound of BOD removed.





                       Ib solids        AXV
                        Ib BODr    Q(S  - S




where



    AX^ = volatile sludge produced, Ib/day



      Q = waste flow, mgd



     SQ = influent BOD   mg/£



     S  = effluent soluble BODC, mg/£
      e                       j


    7.  Calculate the solids retention time.



                                 XB(V)(8.3U)

                            t  =  a
                                     AXy


where



     t  = solids retention time, days
      S


     X  = MLSS, mg/£
      a


      V = volume of aeration tank, million gal




    AXV = volatile sludge produced, Ib/day








                                 7-112

-------
     8  Determine the effluent soluble BOD,..
     ~~                                    5
                              S    1 + kXt
                               o         V
where
    S  = soluble effluent BOD, mg/£



    S  = influent BOD, mg/£



     k = rate constant, 1/mg/hr



    Xy = MLVSS, mg/£



     t = aeration time, hr



     9.  Calculate sludge recycle ratio.
                              3       X
                               r       a
                             Q      X  - X
                              avg    u    a

vhere
      Q  = volume of recycled sludge, mgd



    ^    = average flow, mgd
                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                                 29 Sep  78
      X  = MLSS, mg/£
       Qu



      X  = suspended solids concentration in returned sludge, mg/l



    10  Calculate the nutrient requirements for nitrogen
                              N = 0.123AX^



and phosphorus



                              P = 0.026AX


where



    AX^ = sludge produced, Ib/day




                                7-H3

-------
EM 1110-2-501
Part 1 of 3

   29 Sep 78

7-39-  Output Data.

    a.  Aeration Tank.

     (1)  Reaction rate constant,  1/mg/hr.

     (2)  Sludge produced per  BOD  removed.

     (3)  Endogenous  respiration rate  (b, b').

     (M  0  utilized per BOD  removed.

     (5)  Influent nonbiodegradable  VSS, mg/£.

     (6)  Effluent degradable  VSS, mg/£.

     (7)  lb BOD/lb MLSS-day (F/M).

     (8)  Mixed  liquor  SS, mg/£ (MLSS).

     (9)  Mixed  liquor  VSS, mgA (MLVSS).

    (10)  Aeration time,  hr,

    (11)  Volume  of aeration tank, million gal.

    (12)  Oxygen  required, Ib/day.

    (13)  Sludge  produced, Ib/day.

    (ih)  Nitrogen requirement, Ib/day.

    (15)   Phosphorus requirement, Ib/day.

    (16)   Sludge  recycle  ratio, percent.

    (17)   Solids  retention time, days.

   "b.   Diffused Aeration System

    (l)  Standard  transfer efficiency,  percent.

    (2)  Operating transfer efficiency, percent.

    (3)  Required  air flow, cfm/1000 ft3

-------
                                                            EM 1110-2-501
                                                              Part 1 of 3
                                                                 29 Sep 78
     c.   Mechanical Aer'ation System.
     (l)   Standard transfer efficiency,  Ib 0 /hp-hr.
     (2)   Operating transfer efficiency, Ib 0 /hp-hr.
     (3)   Horsepower required.
 7-^0.  Example  Calculations (Eckenfelder's Approach).
     a.   Assume  the following design  parameters.
      (1)   a - 0.73
      (2)   a' =  0.52
      (3)   b = 0.075/day, V  =  0.15/day
      (If)   a  =  0.56
           o
      (5)   f = 0.140
      (6)   MLSS  = X  = ^000 mg/£
                   £t
      (7)   MLVSS =  Xy = 2800 mg/£
      (8)   0 = 1.02
      (9)   f =  0.53
     (10)  F/M = 0.10
     (11)  Sg = 10 mg/£
    b.  Adjust the BOD removal rate constant for temperature.


where
       = removal rate constant at desired temperature, °C
        = removal rate constant at 20°C, 0.0010
                                 7-115

-------
EM 1110-2-501
Part 1 of 3
 29 Sep 78
     e = 1,02

     T = 15°C


                          KT = 0.001(1.02)15~2°

                          Km = 0.0009
    c.  Determine the size of the aeration tank.

                              a (S  - S )Q
                          v -           '^
                          v"
where

       V = volume of aeration tank, million gal

      a  = 0.56
       o

      S  = influent BOD ,  200 mg/£

      Sg = effluent soluble BOD   10 mg/£

    Qa   = average flow, 1.0 mg/£

      Xy = MLVSS, 2800

      f = 0.53

       "b = 0.075/day
                            0.56(200 - 10)1.0
                             2800(0.53)0.075
                        V = 0.96 million gallons

    d.   Calculate detention time
                                      24
                                 7-116

-------
                                                          EM 1110-2-501
                                                            Part 1 of 3

                                                               29 Sep $8

where

    t = detention time,  hr

    V = volume,  0.96 million gal

    Q = average  flow, 1.0 mgd
                                t = 23 hr


    e.  Assume organic loading and calculate  detention  time.
                               u ~ yF/M)

where

      t = detention time, hr

     S  = influent BOD_, 200 mg/£
      o               5
     X  = MLVSS, 2800 mg/£

    F/M =0.10

                               -  2M200)
                                 2800(0.10)

                                t = 17 hr

Select longer detention time,  t = 23 hr

    f.   Determine oxygen requirements allowing 60 percent  for nitrifi-
cation during summer.
                                7-117

-------
EM 1110-2-501

Part 1 of 3

  29 Sep 78



where



      00 = oxygen required, lb/day



      a' = 0.56



      s  = s  - s  = 190 vis/a
       r    c    e


    Q    = average flow, 1.0 mgd
     "• * o


      b1 = 0.15/day



      Xy = MLVSS, 2800 mg/£



       V = voluiae of aeration tank, 0.96 million gal



    ^•57 ~ parts oxygen required per part TKW



     TKN = total Kjeldahl nitrogen, 30 mg/£




       0^ = [C.5^(190)1-0 + 0.15(2800)0.96 + 0.6(It. 57)30(1. 0)]8.




                            0,,; = 4936 lb/day
        Calculate oxygen required per pound of BOD removed.
                                   Q   (S
                                    avg  r
where



      0  = oxygen required, kyz6 lb/day



    Q    = average flow, 1.0 mgd
     avg                      &


      S  = BOD removed, 190 mg/£
                          lb 0

                         	2_ _     ^936
                         lb BODr   190(1.0)8.






                                7-118

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3

                                                                29 Sep 78
                           Ib 00
                               *-  = 3.0 > 1.5 (OK)
                          Ib BOD
                                r
    h.  Design aeration system (diffused).

    (l)  Assume the following design parameters.

    (a)  STE =5.0$

    (b)  a = 0.9

    (c)  3 = 0.9

    (d)  p = 1.0

    (2)  Select summer operating temperature and determine oxygen
saturation (C),  T = 25°C ,  and    cs   =8.2 mg/A .
             g

    (3)  Determine operating transfer efficiency.
[(ca)
                                UXp> -
                              ' m          ^ I        ft! op,
                OTE = STE	~-^	—-=*• a (1.0?)J  U

where

      OTE = operating transfer efficiency, percent

      STE = standard operating efficiency, 5.0 percent

    (C \  =8.2 mg/£
    V S/T
        e = 0.9

        P = i.o

    9.17 = 0,. saturation at 20°V

      C  = minimum dissolved oxygen concentration, 2.0 mg/£

       a = 0.9

       T = 25°C

                                 7-119

-------
EM 1110-2-501
Part 1 of 3
  29  Sep  78
                  = 5.0 [8.2(0.9)1.0 - 2.01 0.9(1.02)25-20
                                y •->-1
                               OTE = 2.'
         Calculate the required air flow.

                                 00(io)57.W
                       R  =
                            OTE(0.0176)1UUO(V)106
where
                                           o
        R  = required air flow, cfm/1000 ft
         a

        0  = oxygen required, ^936 Ib/day

       OTE = operating transfer efficiency, 2.9%

    0.0176 = Ib 0 /ft3 air

         V = volume of aeration tank, 0.96 million gal
                      a   2. 9(0. 0176)1^0(0. 96)106
                          R  = 52.3 cfm/1000 ft3
                           a
    (5)  Calculate horsepower required.

                                  0^(1000)
                           hp =
                                OTE(2lOV(lO )
where
     0  = oxygen required, ^936 Ib/day

    OTE = operating transfer efficiency, 2.9%

      V = volume of aeration tank, 0.96 million gal


                                 7-120

-------
                         hp =
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                29 Sep 78
                                 U936(1000)
                              2.9(2*00.96(106)
                 hp = 0.07U hp/1000 gal < 0.1 hp/1000 gal

                           Use 0.1 hp/1000 gal

                      Total hp = 0.1(V)1000

                            hp = 0.1(0.96)1000

                            hp = 96 hp; use 100 hp

    i.  Calculate sludge production.


 AXy  =  [a(Sr)(Q) -  (b)(Xy)(V) - Q(SSeff) + Q(VSS)f + Q(SS -

where

      AX^ = sludge produced, Ib/day

        a = 0.73

       S  = BOD removed, S  - S  = 190 mg/£

        Q = average flow, 1.0 mgd

        t = 0.075/day

       Xy = MLVSS,  2800 mg/£

        V = volume  of aeration tank, 0.96 million gal

    SS    = solids  in effluent,  20 mg/£

      VSS = volatile solids in influent,  150 mg/£

       f = 0.53

       SS = solids  in influent,  200 mg/Jl
                                7-121

-------
EM 1110-2-501

Part 1 of 3

   29 Sep 78

            = [0.73(190)1.0 - 0.075(2800)0.96 - 1.0(20)


                            + 1.0(150)0.53 + 1.0(200 - 150)]8.3U



                            AX  = 389 Ib/day
      .  Calculate solids produced per pound of BOD removed.


                       113 solids _      AXV _
                        lb BOD



where


    AX^ = sludge produced, 389 Ib/day


       Q = average flow, 1.0 mgd


     S = influent BOD, 200 mg/£
       o

     S = effluent BOD, 10 mg/£
       e
                          solids _ _ 389
                                  _

                        lb  BOD     1.0(200 - 10)8.3^
     k.   Calculate solids retention time.


                                    X V8.3H
                               .      a
 vhere


      t  = solids retention time, days
       s


      X  = MLSS, >*000 mg/£
       a

       V = volume of aeration tank, 0.96 million gal



     AX^ = solids produced, 389 Ib/day


                                 7-122

-------
                             _ ^000(0.96)8.:

                           s "     389


                              t  = 82 days
    1.  Determine effluent soluble BOD .



                             S       ..
                              e      1
                             SQ   1




vhere



    S  = soluble effluent BOD, mg/£
     e


    S  = influent BOD, 200 mg/H
     o


     k = reaction rate constant, 0.0009



    X  = MLVSS, 2800 mg/£



     t = detention time, 23 hr




                       S
                       200   1 + (0.0009)2800(23)
                              S  =3.^ mg/£
    m.  Calculate sludge recycle ratio.
                                      X
                                       a
                             }      X  - X
                              avg    u    a
where
      Q  = recycle flow, mgd



     1    = average flow, 1.0 mgd
     avg


      X  = MLSS, 1^000 mg/i
       a


      X  = underflow concentration, 10,000 rag/a
                                1-123
                                                           EM 1110-2-501

                                                             Part  1 of 3


                                                               29  Sep  78

-------
EM 1110-2-501
Part 1 of 3

 29 Sep 78
                          1.0   10,000 - 1+,000
                              Q  =0.67 mgd
    n.  Calculate nutrient requirements for nitrogen.

                            N = 0.123AX^

                            N = 0.123(389)

                            N = hQ It/day

for phosphorus

                            P = 0.026AX
                                       v

                            P = 0.026(389)

                            P = 10 Ib/day

                  N in influent = 30 mg/«,(Q)8.3l*

                                = 30(1.0)8.3^

                                = 250 lt>/day > U8 It/day

                          N to "be added = none

                  P in influent = 15 mg/£(Q)8.3It

                                = 15(1.0)8.3^

                                = 125 Ib/day > 10 Ib/day

                          P to be added = none


7-^1.  Cost Data.  Appropriate cost data and economic evaluation may
be found in Chapter 8.


                                7-121*

-------
                                                            EM 1110-2-501
                                                              Part  1  of  3
                                                               29  Sep 78
7-U2.  Bibliography.

    a.  American Public Health Association, American Society of Civil
Engineers, American Water Works Association, and Water Pollution Control
Federation, "Glossary, Water and Wastewater Control Engineering,"  1969.

    b.  American Public Works Association, "Feasibility of Computer
Control of Wastewater Treatment," Report No. 17090DOY, Dec 1970, U. S.
Environmental Projection Agency, Washington, D. C.

    c.  American Society of Civil Engineers and the Water Pollution
Control Federation, "Sewage Treatment Plant Design," Manual of Practice
No. 8, 1959, 1961, 1967, and 1968, Water Pollution Control Federation,
Washington, D. C.

    d.  Bargman, R. D. and Borgerding, J.. , "Characterization of the
Activated Sludge Process," Report No. R2-73-22U, Apr 1973, U. S. Envi-
ronmental Protection Agency, Washington, D. C.

    e.  Busch, A. W., Aerobic Biological Treatment of Wastewaters,
Oligodynamics Press, 1971-

    f.  Center for Research, Inc., University of Kansas, "Oxygen Con-
sumption in Continuous Biological Culture," Report No. 17050DJS, May
1971, U. S. Environmental Protection Agency, Washington, D. C.

    g.  City of Austin, Texas, "Design Guides for Biological Wastewater
Treatment Processes," Report No. 11010ESQ, Aug 1971, U. S. Environmental
Protection Agency, Washington, D. C.
                                                            V
    h.  Eckenfelder, W. W., Jr., Industrial Water Pollution Control,
McGraw-Hill, New York, 1966.

    i.  Eckenfelder, W. W., Jr., "General Concepts of Biological Treat-
ment," Manual of Treatment Processes, Vol 1, 1969, Environmental Science
Services, Inc., Briarcliff Manor, New York.

    j.  Eckenfelder, W. W., Jr., Water Quality Engineering for
Practicing Engineers, Barnes and Nobel, New York, 1970.

    k.  Eckenfelder, W. W., Jr., "Activated Sludge and Extended
Aeration," Process Design in Water Quality Engineering - New Concepts
and Developments, 1971, Vanderbilt University, Nashville, Tenn.
                                 7-125

-------
 EM 1110-2-501
 Part 1 of 3
  29  Sep 78

     1.   Eckenfelder,  W. W.,  Jr.,  and  Ford,  D.  L., Water  Pollution
 Control, Pemberton  Press, New York, 1970.                      '

     m.   Eckenfelder,  W. W.,  Jr.,  and  O'Connor,  0. J., Biological Waste
 Treatment, Pergamon Press, New York,  1961.

     n.   Gaudy, A. G., Jr., and Gaudy, E. T., "Biological Concepts  for
 Design and Operation  of the  Activated Sludge Process," Report No.  17090-
 FQJ,  Sep 1971, U. S.  Environmental Protection Agency, Washington,  D. C.

     o.   Goodman, B. L. , Design Handbook of Wastewater Systems:  Domestic.
 Industrial, Commercial, Technomic, Westport, Conn., 1971.

     p.   Goodman, B. L. and Englande, A. J., Jr., "A Consolidated Approach
 to Activated  Sludge Process  Design,"  Conference on Toward a Unified Con-
 cept  of Biological Waste Treatment Design, 5-6 Oct 1972, Atlanta,  Ga.

     q.   Lawrence, A. W. and McCarty, P. L., "Unified Basis for Biolog-
 ical  Treatment Design and Operation," Journal, Sanitary  Engineering
 Division, American Society of  Civil Engineers, Vol 96. SA.VT 1Q707

    r.  Maier, W. J., "Biological Removal of Colloidal Matter from
 Wastewater," Report No. R2-73-1V7, Jun 1973, U. S.  Environmental Pro-
 tection Agency, Washington, D. C.

    s.  McCarty, P.  L., and Brodersen, C.  F., "Theory of Extended
 Aeration Activated Sludge," Journal, Water Pollution Control Federation.
 Vol 3!*, 1962,  pp 1095-1103.       '             ~                    ~~

    t.  McKinney, E. E., Microbiology for  Sanitary Engineers, McGraw-
 Hill, New York, 1962.

    u.  Metcalf and Eddy, Inc., Wastewater Engineering;  Collection,
 Treatment, and Disposal, McGraw-Hill,  New  York, 1972.

    v.  Okun,  D.  A., "System of Bio-Precipitation of Organic Matter
 from Sewage,"  Sewage Works Journal,  Vol 21,  No.  5,  19^9,  pp 763-79!*.

    w.  Smith, H. S.,  "Homogeneous Activated Sludge Principles and
Features of the Activated Sludge Process," Water and Wastes Engineering,
Vol h, Jul 1967,  pp  1+6-50.                  ~~                   	
                                 7-126

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29  Sep  78

    x.   Smith, R., and Eilers, R. G.,  "A Generalized Computer Model for
Steady-State Performance of the Activated Sludge Process," FWQA Report
No. TWRC-15, Oct 1969, Robert A. Taft  Water Research Center, Cincinnati,
Ohio.

    y.   Stensel, H. D. and Shell, G. L., "Two Methods of Biological
Treatment Design," Journal, Water Pollution Control Federation, Vol 1*6,
Feb 197U, pp 2T1-283.

    z.   Stewart, M. J., "Activated Sludge System Variations - Specific
Applications," The 15th Ontario Industrial Waste Conference, 9-12 Jun
1968, Niagara Falls, Ontario.

    aa.  Toerber, E. D., "Full Scale Parallel Activated Sludge Process
Evaluation," Report No. R2-72-065, Nov 1972, U. S. Environmental Protec-
tion Agency, Washington, D. C.

    bb.  Weston, R. F., "Design of Sludge Reaeration Activated Sludge
Systems," Journal, Water Pollution Control Federation, Vol 33, No. 7,
1961, pp 7^8-757-
                                 7-127             (next page is 7-129)

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                                                           EM 1110-2-501
                                                             Part  1  of  3
                                                               29  Sep 78

      Section VII.   MODIFIED OR HIGH-RATE AERATION ACTIVATED SLUDGE

T-U3.   Background.

    a.  Modified or high-rate aeration activated sludge is  defined as
"a modification of the activated sludge process in which a  shortened
period of aeration is used with a reduced quantity of suspended solids
in the mixed liquor," (para T-50a).   The flow diagram is the same  as
that for the plug-flow process (fig.  7-6); the difference in the process
    INFLUENT
                 AERATION TANK
                SLUDGE RETURN
EFFLUENT
  WASTE
                                                          SLUDGE
                 Figure 7-6.  Plug flow activated sludge.
design parameters (shorter detention time and lower mixed liquid sus-
pended solids) results in less air requirements and, hence, less power
consumption.  Modified aeration is also characterized by a poor settling
sludge and low BOD removal efficiencies.

    b.  Process design parameters and discussion of applications are
given in References c, t, and y in paragraph 7-50 below.

1-kh.  Input Data.

    a.  Wastewater Flow  (Average and Peak).  In case of high variabil-
ity, a statistical distribution should be provided.

    b.  Wastewater Strength.

     (l)  BOD   (soluble and total), mg/£.

     (2)  COD and/or TOC  (maximum and minimum), mg/JU

     (3)  Suspended solids, mg/£.

     (h)  Volatile suspended solids  (VSS), mg/Jl.
                                 7-129

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EM 1110-2-501
Part 1 of 3
29  Sep 78

    (5)   Nonbiodegradable fraction of VSS,  mg/£.

    c.   Other Characterization.

    (1)   PH.

    (2)   Acidity and/or  alkalinity, mg/£.

    (3)   Nitrogen,1 mg/£.

    (h)   Phosphorus  (total and soluble), mg/£.

    (5)   Oils and greases,  mg/£.

    (6)   Heavy metals, mg/£.

    (7)   Toxic or special  characteristics (e.g., phenols), mg/£.

    (8)   Temperature, °F or °C.

    d.  Effluent  Quality Requirements.

    (1)   BOD   mg/£.

    (2)   SS,  mg/£.

    (3)   TO,  mg/£.

         P, mg/£.
    (5)  Total nitrogen (TKN + NO -W) , mg/£.

    (6)  Settleable solids, mg/£.

  5.  Design Parameters.

   a.  Reaction rate constants and coefficients.
  The form of nitrogen should be specified as to its biological
 availability (e.g., KH  or Kjeldahl).


                               7-130

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                                                        EM 1110-2-501

                                                          Part 1 of 3

                                                            29 Sep 78
             Eckenfelder



                 k               0.0007-0.002 £/mg/hr



                 a               0.73



                 a'               0.52



                 b               0.075/day



                 b'               0.15/day



                 f               O.UO



                 f               0.53



 b.   F/M = (1.5-5.0).



 c.   Volumetric  loading = 100-250.



 d.   t  = (1.5-3-0) hr.



 e.   t   = (0.2-0.5)  days.
      s


 f.   MLSS = (200-1000)  mg/a.



 g.   MLVSS = (lllO-TOO)  mg/Si.



 h.   Qr/Q = (0.05-0.15).



 i.   Ib 02/lb BODr = (0.5-0.75).



 j.   Ib solids/lb BOD   = (0.65-0.85).



 k.   Efficiency  = (50-60 percent).



5.   Design Procedure (Eckenfelder's Approach).



 a.   Assume the  following design  parameters when unknown.



 (l)  Fraction of BOD  synthesized (a).



 (2)  Fraction of BOD  oxidized for  energy (a1).






                              7-131

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 EM 1110-2-501
 Part 1 of 3

  29 Sep 78

     (3)  Endogenous  respiration rate  (b and b')


     (U)  Mixed liquor  suspended solids  (MLSS).


     (5)  Mixed liquor  volatile  suspended solids  (MLVSS).


     (6)  Food-to-microorganism  ratio  (F/M).

     (T)  Temperature correction coefficient  (Q}.


     (8)  Wonbiodegradable fraction of VSS in influent  (f).

     (9)  Degradable fraction of the MLVSS (f).


     b.  Determine the  size of the aeration tank by first determining
the  detention  time.


                                    2kS
                              t  =
where

      t = detention time, hr

     SQ = influent BOD, mg/£

     Xy = MLVSS, mg/l

    F/M = food-to-microorganism ratio

    c.   Calculate the volume of aeration tank.



                             v = Qavg(
where

       V = volume of aeration tank, million gal

    Qavg = average daily flow, mgd

       t = detention time,  hr

    d.   Calculate oxygen requirements.


                                7-132

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                29  Sep  78
                              at
or
                         00 = a'(S )(Q   ) (8.310
                          2       r   avg
where
    ao/at = oxygen uptake rate, mg/£/hr
       a* = fraction of BOD oxidized for energy
       S  = BOD removed (S  - S ), mg/£
        t = detention time, hr
       0  = oxygen uptake rate , l"b/aay
     Q    = average flow rate, mga
      avg
    e.  Check the oxygen supplied against pounds of BOD removed
(0.5-0.7).

                         o2/ib
where
    0  = oxygen required, Ib/day
     Q = flow, mgd
    S  = BOD removed, mg/£
    f.  Design Aeration System.
    (l)  Diffused aeration system.
    (a)  Assume the following design parameters.
    !_  Standard transfer efficiency, percent, from manufacturer
 5-8 percent) .
                                 7-133

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EM 1110-2-501

Part 1 of 3

  29  Sep  78



    2_  0  transfer in waste/0? transfer in water «0.9.



    _3_  00 saturation in waste/0^ saturation in water aO.9.



    k_  Correction factor for pressure s»1.0.



    (b)  Select summer operating temperature (25-30°C) and determine

(from standard tables) 0^ saturation.
                        CL


    (c)  Adjust standard transfer efficiency to operating conditions.
                         [(Cs)
                                B) 2,0 mg/£


        a = 0  transfer in waste/0  transfer in water »<3.9


        T = temperature, °C



    (d)  Calculate required air flow.
                                0

                 R  =
                  a         /        Ib 0
                                            I

                      (OTE) 0.0176 -rr—MpMo

                            V       ft3 air/V
                                                 day I
                            \       X O  t-liJ-J. /  >         '


where



     R  = required air flow, cfm/1000 ft3
      3-



                                 7-13U

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                                                           EM  1110-2-501
                                                             Part  1  of  3
                                                               29  Sep 78
     0? = oxygen required, Ib/day

    OTE = operating transfer efficiency, percent

      V = volume of basin, gal

    (2) Mechanical aeration system.

    (a)  Assume the following design parameters.

    JL  Standard transfer efficiency, lb/hp-hr  (0 dissolved oxygen,
20°C, and tap water).

    2_  Q  transfer in waste/0p transfer in water ssO.9.

    3.  Og saturation in waste/0? saturation in water »0.9.

    h_  Correction factor for pressure ad.O.
    (b)  Select summer operating temperature (25-30°C) and determine
    m standard tables) 0  saturation.

    (c)  Adjust standard transfer efficiency to operating conditions.
                       - CLI
OTE = STE	x     	=J- a(l.02)T 2°
                                          -J
where

      OTE = operating transfer efficiency, Ib 0 /hp-hr

      STE = standard transfer efficiency, Ib 0 /hp-hr

    (Cs)  = 0  saturation at selected summer temperature T, °C, mg/£

        3=0  saturation in waste/0_ saturation in water a^O.Q
             d.                      cL

        p = correction factor for pressure sd..O

       C  = minimum dissolved oxygen to be maintained in the basin
        L   >2.0    '
                                7-135

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EM 1110-2-501
Part 1 of 3
  29  Sep  78

        a = 0  transfer in waste/0  transfer in water

        T = temperature, °C

     (d)  Calculate horsepower requirement.


                                °2
                    hp =  —      - x 100°
where

     hp = horsepower required/1000 gal

     0  = oxygen required, Ib/day

    GTE = operating transfer efficiency

      V = volume of basin, gal

    (e)  Calculate sludge production.



           AXy = [aSrQavg + fQ(VSS) + Q(SS - VSS)] 8.3^


where

     AT  = sludge produced, Ib/day

       a = fraction of BOD removed synthesized to cell material

      S  = BOD removed, mg/£

    Q    = average flow, mgd

       f = nonbiodegradable fraction of VSS in influent

       Q = flow, mgd

     VSS = volatile suspended solids, mg/£

      SS = suspended solids in influent, mg/Jt


                                7-136

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
    (f)  Check AX  against 0.65-0.85 lb solids/lb
AXV
                    Ib solids _
                    (lb BOD )   S
where

    AX^ = sludge produced, Ib/day

     S  = BOD removed, mg/£

      Q = flow, mgd

    (g)  Calculate sludge recycle ratio.
                              Q      X
                              ^r      a
                              Q    X  - X
                                    u    a

where

    Q  = volume of recycled sludge, mgd

     Q = flow, mgd

    X  = MLSS
     a
    X  = suspended solids concentration in returned sludge,
     u
    (h)  Calculate solids retention time.
                             V(X )8.31t
                       SET = 	^	 (% volatile)
where

    SRT = solids retention time, days

      V = volume of basin, million gal


                                 7-137

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EM 1110-2-501

Part 1 of 3

 29  Sep 78
     X  = MLSS
      a


    AX  = sludge produced, Ib/day
      a


    (i)  Estimate effluent BOD .
BOD)
                                           BOD
                            5eff
where
      S  = influent BOD , mg/£



    BOD  = BOD removed, percent



    (j)  Determine nutrient requirements for nitrogen




                              N = O.iaSAX^



and phosphorus



                              P = 0.026AXy



where



    AX  = sludge produced, Ib/day



and check against BOD:W:P = 100:5:1.



T-Vf.  Output Data.



    a.  Aeration Tank.



     (l)  Reaction rate constant, 1/mg/hr.



     (2)  Sludge produced per BOD removed.



     (3)  Endogenous respiration rate (t>, b1).



     (^)  0  utilized per BOD removed.



     (5)  Influent nonbiodegradable VSS, mg/SL.





                                 7-138

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                                                      EM 1110-2-501
                                                        Part 1 of 3

                                                          29 Sep 78
 (6)  Effluent degradable VSS,

 (T)  lb  BOD/lb MLSS-day  (F/M ratio).


 (8)  Mixed  liquor  SS, mg/£  (MLSS).


 (9)  Mixed  liquor  VSS, rngA (MLVSS).


(10)  Aeration time,  hr.

(11)  Volume of  aeration  tank,  million  gal.


(12)  Oxygen required,  Ib/day.


(13)   Sludge produced,  Ib/day.

(lU)   Nitrogen requirement,  Ib/day.


(15)   Phosphorus requirement, Ib/day.


(16)   Sludge recycle ratio,  percent.


(IT)   Solids retention time, days.
                                        3
(18)   Volumetric loading, lb BOD/1000 ft .


b.  Diffused Aeration System.

(l)  Standard transfer efficiency, percent.


(2)  Operating transfer efficiency, percent.

 (3)  Required air  flow, cfm/1000 ft .

c.  Mechanical Aeration System.

 (1)  Standard transfer efficiency,  lb  02/hp-hr.

 (2)  Operating transfer efficiency, lb 02/hp-hr.


 (3)  Horsepower  required, hp.
                              7-139

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EM 1110-2-501
Part 1 of 3
 29 Sep 78

T-^8.  Example Calculations.

    a.  Assume the following design parameters,

    (1)  a = 0.73

    (2)  a' = 0.52

    (3)  b = 0.075/day, V = 0.15/day

    (1*)  MLSS = X  =600 mg/£
                 3,

    (5)  MLVSS = Xy = 1*20 mg/£

    (6)  F/M = 3.0

    (7)  9 = 1.02

    (8)  f = 0.1*0

    (9)  f = 0.53

    b.   Calculate the detention time.

                                    2US
                               t =
                                   X^F/M)
where

      t = detention time, hr

     S  = influent BOD, 200 mg/Z

     Xy = MLVSS, 1*20 mg/£

    F/M = food to microorganism, 3.0
                                - 2M200)
                              t ~ 1*20(3.0)
                               t = 3.8 hr

    c.  Calculate the volume of the aeration tank.

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                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                               29  Sep 78
                              V = Qavg 2?


where


       V = volume of aeration tank, million gal


    0    = average flow, 1.0 mgd
     avg

       t = detention time, 3-8 hr



                              V = 1.



                          V = 0.158 million gal


    d.  Calculate the oxygen requirements.







where


       0  = oxygen requirements, It/day



       a1 = 0.52


       S  = BOD removed  (S  - S  ) = 200 -  100 = 100 mg/A


    Q    = average  flow, 1.0 mgd
     avg


                          0  =  0.52(100)1.0(8.
                              0  =  1*31*  It/day



     e.   Check oxygen supplied against  pounds  of BOD removed (0.5-0.7)



                                            °2
                         It 0/1* BODr  = Q(s )8>3U
                                            r


 where


     0  = oxygen required, ^3^ Ib/day



                                 7-lUl

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 EM 1110-2-501

 Part 1 of 3


   29 Sep  78
      Q = average flow,  1.0 mgd




      ^ = BOD removed, 100 mg/£
                       lb  O./lb  BOD  -
                           2'-  ^  r    1.0(100)8.3U





                         lb 02/lb BODr  =  0.52  (OK)





     f.  Design aeration  system.




     (l)  Assume the following parameters.




     (a)  STE = 5.0$




     (b)  a = 0.9




     (c)  3 = 0.9




     (d)  p = l.o




     (2)  Select summer operating temperature and determine 0  saturation

I - 25 C, 02 = 8.2 mg/£.                                    2




     (3)  Adjust standard transfer efficiency to operating conditions.


                            [(C } 0p - CT~]
                            I \ s y       ]_j i

                  OTE = STE !=	±j-^	=! a(l.02)T-20



where




      OTE = operating transfer efficiency, percent




      STE = standard transfer efficiency, 5.0 percent




    (Cs)  = °2  saturatlon at summer temperature,  8.2 mg/£



        3  = 0.9




        P  = 1.0




       C  = minimum dissolved oxygen,  2.0 mg/£

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                                                           EM 1110-2-501
                                                             Part  1  of 3

                                                               29  Sep 78
        a  =  0.9

        T  =  summer temperature,  25°C
              OTE = 5>0 [8.2(0.9)1.0 - 2.0]  (0.9)1.0225-20


                               OTE =2.9%
    (k)  Calculate horsepower requirement.


                                   0- 1000
                           hp = 	T
                                OTE(2U)V(10

where


     hp = horsepower required/1000 gal
     0  = oxygen required, ^3^ Ib/day


    OTE = operating transfer efficiency, 2.9%


      7 = volume of aeration tank, 0.158 million gal
                         hP = —	f.
                              2.9(2^)0.158(10°)


    hp = 0.01+ hp/1000 gal < 0.1 hp/1000 gal required for mixing.


Therefore

                          hp - 0.1 hp/1000 gal


                            hp = 0.1(7)1000


                            hp = 0.1(0.158)1000


                         hp = 15.8 hp, use 20 hp


    g.   Calculate  sludge production.


                               H  f(Q)VSS + Q(SS -

-------
 EM 1110-2-501
 Part 1 of 3
  29 Sep 78

 where

      AXy = sludge production,  Ib/day

        a = 0.73

       S^ = BOD  removed, 100 mg/£

     Qavg = average flov, 1.0 mgd

        f = O.hO

     VSS = volatile suspended  solids in effluent, 150 mg/Ji

       SS = suspended solids influent, 200 mg/£


         AXy = [0.73(100)1.0 +  0.1*0(1.0)150 + 1.0(200 - 150)]8.3U

                           AXy = 1526 Ib/day

    h.   Check  AX.  against 0.65-0.55 lb solids/lb BOD .
                 v                                    r


                         lb solids _    AXy
                          Ib BODr  ~ Sr(Q)8.3^
where

          AXy = sludge produced, 1526 Ib/day

           S^ = BOD  removed,  100 mg/£

            Q = average flow,  1.0 mgd

    lb solids _     1526
     lb BOD^    100(1.0)8.34
                         lb solids  _
                          lb BOD   ~   '
                                r

    i.   Calculate  sludge  recycle ratio.

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                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                                29 Sep 78
                                     X
                                      a
                                      - Xa
where
    Q  = volume of recycled sludge, mgd



     Q = average flow, mgd



    X  = MLSS, 600 mg/£
     a


    X  = suspended solids in returned sludge, 10,000 mg/£
                                     600
                           1.0   10,000 - 600
                              Q  =0.06 mgd
    j.  Calculate solids retention time.



                            V(X )8.3M$ volatile)

                      SRT = 	—
                                     AX
                                       a

where



           SRT = solids retention time, days



             V = volume of aeration tank, 0.158 million gal



            X  = MLSS, 600 mg/£
             Q,


           AX  = sludge produced, 1526 Ib/day
             cl
      volatile = 10%
                        vw - 0.158(600)6.3MO.7)
                        SRT
                             SRT =0.36 days
    k.  Estimate effluent BOD .
                                7-1*15

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 EM 1110-2-501

 Part 1 of 3

  29 Sep 78
                                         BOD
                          BOD, = S   1 -
                              5    o\^   100

vhere



      S0 ~ influent BOD, 200 mg/£


    BOD^ = BOD removed, 50$
                                  = 100 mg/SL



    1.  Determine nutrient requirements for nitrogen



                            N = 0.123 AXy


                            N = 0.123(2180)


                            N = 268 Ib/day


for phosphorus



                            P = 0.026 AXy


                            P = 0.026(2180)


                            P = 57  Ib/day


                 N in  influent =  30 mg/£  Q    8.3^
                                          avg


                               =  30(1.0)8.34


                               =  250  Ib/day <  268 Ib/day


                 N to  be added =  18 lb/day



                 P in  influent  =  15 mg/£  Q     8.3^
                                         avg


                               =  15(1.0)8.34


                               =  125 Ib/day >  57 Ib/day


                 P to be added  = none


                                7-11*6

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                29 Sep 78

7-^9-  Cost'Data.  Appropriate cost data and economic evaluation may be
found in Chapter 8.

7-50.  Bibliography.

    a.  American Public Health Association, American Society of Civil
Engineers, American Water Works Association, and Water Pollution Control
Federation, "Glossary, Water and Wastewater Control Engineering," 1969.

    b.  American Public Works Association, "Feasibility of Computer
Control of Wastewater Treatment," Report No. 17090DOY, Dec 1970, U. S.
Environmental Protection Agency, Washington, D. C.

    c.  American Society of Civil Engineers and the Water Pollution
Control Federation, "Sevage Treatment Plant Design," Manual of Practice
No. 8, 1959, 1961, 1967, and 1968, Water Pollution Control Federation,
Washington, D. C.

    d.  Bargman, R. D. and Borgerding, J., "Characterization of the
Activated Sludge Process," Report No. R2-73-22^, Apr 1973, U. S. Envi-
ronmental Protection Agency, Washington, D. C.

    e.  Busch, A. W., Aerobic Biological Treatment of Wastewaters,
Oligodynamics Press, 1971-

    f.  Center for Research, Inc., University of Kansas, "Oxygen Con-
sumption in Continuous Biological Culture," Report No. 17050DJS, May
1971, U. S. Environmental Protection Agency, Washington, D. C.

    g.  dity of Austin, Texas, "Design Guides for Biological Wastewater
Treatment Processes," Report Wo. 11010ESQ, Aug 1971, U.  S. Environmental
Protection Agency, Washington, D. C.

    h.  Eckenfelder, W. W., Jr., Industrial Water Pollution Control,
McGraw-Hill, New York, 1966.

    i.  Eckenfelder, W. W., Jr., "General Concepts of Biological Treat-
ment," Manual of Treatment Processes, Vol 1, 19&9* Environmental Science
Services, Inc., Briarcliff Manor, New York.

    j.  Eckenfelder, W. W., Jr., Water Quality Engineering for Practicing
Engineers, Barnes and Nobel, New York, 1970.
                                 7-1^7

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EM 1110-2-501
Part 1 of 3
  29  Sep  78

    k.  Eckenfelder, W. W., Jr., "Activated Sludge and Extended Aera-
tion," Process Design in Water Quality Engineering - New Concepts and
Developments, 1971, Vanderbilt University, Nashville, Tenn.

    1.  Eckerif elder, W. W. , Jr., and Ford, D. L. , Water Pollution
Control, Pemberton Press, New York, 1970.

    m.  Eckenfelder, W. W., Jr., and O'Connor, 0. J. , Biological
Waste Treatment, Pergamon Press, New York, 1961.

    n.  Gaudy, A. G., Jr., and Gaudy, E. T., "Biological Concepts for
Design and Operation of the Activated Sludge Process," Report No. 17090-
FQJ, Sep 1971, U. S. Environmental Protection Agency, Washington, D. C.

    o.  Goodman, B.  L., Design Handbook of Wastewater Systems:  Domestic,
Industrial, Commercial, Technomic, Westport, Conn., 1971.

    p.  Goodman, B.  L.  and Englande, A. J., Jr., "A Consolidated Ap-
proach to Activated Sludge Process Design," Conference on Toward a
Unified Concept of Biological Waste Treatment Design, 5-6 Oct 1972,
Atlanta, Ga.

    q.  Lawrence, A. W. and McCarty, P. L., "Unified Basis for Biolog-
ical Treatment Design and Operation," Journal, Sanitary Engineering
Division, American Society of Civil Engineers, Vol 96, SA3, 1970.

    r.  Maier, W. J., "Biological Removal of Colloidal Matter from
Wastewater,"  Report  No. R2-73-l1i7, Jun 1973, U.  S. Environmental Pro-
tection Agency, Washington, D.  C.

    s.  McKinney, R. E. ,  Microbiology for Sanitary Engineers, McGraw-
Hill, New York, 1962.

    t.  Metcalf and  Eddy, Inc., Wastewater Engineering; Collection,
Treatment, and Disposal,  McGraw-Hill, New York,  1972.

    u.  Okun, D.  A., "System of Bio-Precipitation of Organic Matter
from Sewage," Sewage Works Journal,  Vol 21, No. 5, 19^9,  pp 763-79^.

    v.  Smith, H. S., "Homogeneous Activated Sludge Principles and
Features of the Activated Sludge Process," Water and Wastes Engineering,
Vol U, Jul 1967,  pp  46-50.
                                7-1U8

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78

    w.  Smith, R. and Eilers, R. G., "A Generalized Computer Model for
Steady-State Performance of the Activated Sludge Process," FWQA Report
Mo. TWRC-15, Oct 1969, Robert A. Taft Water Research Center, Cincinnati,
Ohio.

    x.  Stansel, H. D. and Shell, G. L., "Two Methods of Biological
Treatment Design," Journal, Water Pollution Control Federation, Vol ^6,
Feb 197*1, PP 271-283.

    y.  Stewart, M. J., "Activated Sludge System Variations - Specific
Applications," The 15th Ontario Industrial Waste Conference, 9-12 Jun
1968, Niagara Falls, Ontario.

    z.  Toerber, E. D.., "Full Scale Parallel Activated Sludge Process
Evaluation," Report No. R2-72-065, Nov 1972, U. S. Environmental Pro-
tection Agency, Washington, D. C.

    aa.  Weston, R. F., "Design of Sludge Reaeration Activated Sludge
Systems," Journal, Water Pollution Control Federation, Vol 33, No. 7,
1961, pp 7^8-757-
                                7-1)49               (next page  is  7-151)

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                                                           EM 1110-2-501
                                                             'Part 1 of 3
                                                                29 Sep  78

          Section VIII.  CONTACT STABILIZATION ACTIVATED SLUDGE

7-51-  Background.

    a.  The contact stabilization process (fig. 7-7) is defined as "a
modification of the activated sludge process in which raw wastewater is
aerated with a high concentration of activated sludge for a short period,
usually less than 60 min to obtain BOD removal by absorption.  The
solids are subsequently removed by sedimentation and transferred to a
stabilization tank where aeration is continued further to oxidize and
condition them before their reintroduction to the raw wastewater flow"
(para 7-58a).
         INFLUENT
  ALTERNATE
    WASTE
    SLUDGE
                     CONTACT TANK
                                                              EFFLUENT
STABILIZATION
   TANK
                SLUDGE RETURN
                                             WASTE SLUDGE
           Figure 7-7.  Contact stabilization activated sludge.

    b.  Contact stabilization was developed to take advantage of the
absorptive properties of the sludge floe.  Contact stabilization
achieves absorption in the contact tank, and oxidation and synthesis
of removed organics occur in a separate aeration tank.

    c.  The volume requirement for aeration is approximately one-half
of that of a conventional plug-flow unit.  Therefore, it is often
possible to double the capacity of an existing plug-flow plant by simply
repiping or making minor changes in aeration equipment.

    d.  References h, o, t, v, and y in paragraph 7-58, discuss the
contact stabilization variation and suggest rules of thumb for the
design parameters.

7-52.   Input Data.

    a.  Wastewater Flow (Average and Peak).  In case of high variability,
a statistical distribution should be provided.
                                 7-151

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EM 1110-2-501
Part 1 of 3
 29 Sep  78

    b.  Wastevater Strength.

    (1)  BOD  (soluble and total), mg/S..

    (2)  COD and/or TOG (maximum and minimum), mg/S,.

    (3)  Suspended solids, mg/S,.

    (4)  Volatile suspended solids (VSS), mg/S,.

    (5)  Nonbiodegradable fraction of VSS, mg/S,.

    c.  Other Characterization.

    (1)  PH.

    (2)  Acidity and/or alkalinity, mg/S,.

    (3)  Nitrogen,   mg/S,.

    (4)  Phosphorus (total and soluble), mg/S,.

    (5)  Oils and greases, mg/S,.

    (6)  Heavy metals,  mg/S,.

    (7)  Toxic or special characteristics (e.g., phenols), mg/S,.

    (8)  Temperature,  °F or °C.

    d.  Effluent  Quality Requirements.

    (1)  BOD5, mg/A.

    (2)   SS,  mg/£.

    (3)   TKM, mg/£.

    (4)   P, mg/Jl.

    (5)   Total nitrogen  (TKW + No   - N),  mg/S,.


  The  form of nitrogen  should be  specified as  to  its biological
 availability (e.g., NH  or Kjeldahl).

                                7-152

-------
    (6)  Settleatile solids, mg/£.



7.53.   Design Parameters.



    a.  Contact tank detention time,  t^ .



        t1 = (0.5-1-0) hr


    b.  System organic loading  (F/M).



        F/M =  (0.2-0.6).



    c.  Volumetric loading =  60-75-



    d.  Stabilization tank detention  time,



        t  =  (2-U) hr



    e.   Contact  tank MLSS, X   .
                              CtL.


         X    =  (2500-3500)  mgA
         ac


    f .   Contact  tank .MLVSS,   Xvc .


         X    = O.TX   =  (1750-2^50)  mg/£
         vc        ac


     a;.  Stabilization tank MLSS,  X   .
     •->                              do


         X    = (itOOO-8000) mg/A
          as

     h.  Stabilization tank MLVSS,  X^s .



         X   = (2800-5600) mg/fc
          vs

     i.  Air requirement (lb  02/lb BODr).



         Ib 02/lb BODr = 1.25-1-5


     j.  lb solids/lb BODr =  (0.2-O.U).



     k.  Recycle ratio,
          Qr/Q  =  (0.25-1.0)
                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                                29  Sep 78
                                   7-153

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EM 1110-2-501

Part 1 of 3
   29 Sep /8



    1.  Efficiency = (>90 percent).


7-5^-  Design Procedure.


    a.  Assume the following design parameters.


    (l)  Aeration time in contact tank, hr.


    (2)  Aeration time in stabilization tank, hr.


    (3)  MLSS in contact tank, mg/£.


    (4)  MLSS in stabilization tank, mg/£.


    (5)  MLVSS in contact tank, mg/£.


    (6)  MLVSS in stabilization tank, mg/£.


    (7)  0  requirements, Ib/day.


    (8)  Sludge produced, Ib/day.


    b.  Determine contact tank volume.
                            Vc =
where
      V  = volume of contact tank, million gal


    Q    = average flow, mgd


      t  = detention time in contact tank, hr


    c.  Determine stabilization tank volume.




                            V  =
                             s

where



      V  = volume of stabilization tank, million gal

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                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                                 29 Sep 78
    Q    = average flow, mgd
     avg


      t  = detention time in stabilization tank, hr



    d.  Calculate system organic loading and check against desired

loading .



                                       Q   (S )
                     (F/M)       = _ ayg  o

                     ^/M;system   V (X  ) + V (X  )
                                    c  vc     s   vs



where



     F/M = food-to-microorganism ratio



    Q    = average flow, mgd
     avg


      S  = influent BOD , mg/£



      V  = volume of contact tank, million gal



     X   = MLVSS in contact tank, mg/£



      V  = volume of stabilization tank, million gal
       S


     X   = MLVSS in stabilization tank, mg/£



    e.  Calculate volumetric loading and check against desired loading.



                               ,   Q   (S )(62.10

                     ib/iooo ft3 =
                                   (v  + v )
                                     c    s
where
    Q    = average flow, mgd



      S  = influent BOD , mg/£



      V  = contact tank volume, million gal




      V  = stabilization tank volume, million gal
       o
                                 7-155

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 EM 1110-2-501

 Part  1 of 3


  29 Sep 78



    f.   Calculate  the  system oxygen required and select  1.25-1 5 lb

 0 /lb  BOD .




                     0  =  (1.25-1.5)QflTO  x S  (8.3k)
                      £•              avg     r


 where



       02  = required  oxygen,  Ib/day



    Sivg  = averaSe flow, mgd



       S^  = BOD removed (S  - S  ),  mg/£



 Supply  approximately one-half of 0  for contact  tank and one-half for

 stabilization tank.



    g.  Design aeration system.



    (l)  Diffused  aeration system.



    (a)  Assume the  following design parameters.



    1_   Standard transfer efficiency, percent, from manufacturer

 (5-8 percent).



    2_   0  transfer in waste/00 transfer in water s£ 9
        <-                     d.


    3_   02 saturation in waste/0  saturation in water «0.9.



    h_   Correction factor for  pressure «1.0.
    (b)  Select summer operating temperature (25-30°C) and determine

    m standard tables) 0  saturation.



    (c)  Adjust standard transfer efficiency to operating conditions.
                OTE = STE t	T   17	i a(l.02)T"20



where



      OTE = operating transfer efficiency, percent





                                 7-156

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                29 Sep 78
      STE  =  standard  transfer  efficiency,  percent

    (C \   =0   saturation at  selected summer temperature T,  °C,  mg/£
    V S/rji    '-
        3=0   saturation in  waste/0  saturation in water x£).9

        p  =  correction factor for pressure sJ_.0

       C  =  minimum dissolved oxygen to be maintained in the basin
        L    > 2.0 mg/£

        a  =  0   transfer in waste/0  transfer in water stO.9

        T  =  temperature, °C

    (d)  Calculate required air flow.
                  a        /        It 0  '
                      (OTE)lo.0176 —	
                           \       ft  air,
where

     R  = required air flow, cfm/1000 ft
      a
     0  = required oxygen, Ib/day

    OTE = operating transfer efficiency, percent

      V = volume of basin  (V  + V  ), gal
                            S    »—

    (2)  Mechanical aeration system.

    (a)  Assume the following design parameters.

    !_  Standard transfer efficiency, Ib/hp-hr  (0 dissolved  oxygen,
20°C, and tap water).

    2_  0  transfer in waste/0  transfer in water ssO.9-

    3_  0  saturation in waste/0  saturation  in water ssO.9.

    k_  Correction factor for pressure sal.O.


                                 7-157

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EM 110-2-501

Part 1 of 3

  29  Sep  78
     (b)  Select simmer operating temperature (25-30°C) and determine

    m standard tables) 0  saturation.



     (c)  Adjust standard transfer efficiency to operating conditions.
                OTE = STE i -  9~rf -  a(l.02)T~20


where



      OTE = operating transfer efficiency, Ib 0 /hp-hr



      STE = standard transfer efficiency, Ib 0 /hp-hr



          = 02 saturation at selected summer temperature T, °C, mg/£



        3 = 0  saturation in waste/0  saturation in water ssO.9



        p = correction factor for pressure «i.O



       C  = minimum dissolved oxygen to be maintained in the basin

            > 2.0 mg/£



        a = 02 transfer in waste/0  transfer in water *Q.9



        T = temperature, °C



    (d)  Calculate horsepower requirement.




                                  °
                                             X 100°
where



     hp = horsepower required/lOOO gal



     0  = oxygen required, Ib/day



    OTE = operating transfer efficiency



      V = volume of basin (V  + V ) ,  gal
                            o    C



                                 7-158

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                                                           EM 1110-2-501

                                                             Part 1 of 3
                                                                29 Sep 78
    h.   Determine sludge production.   Select 0.2-0. U Ib solids/lb
                            = (0.2-O.U)Q(Sr)8.3U
where


    AX_  = sludge produced, lb/day


      Q = flow, mgd


     S  = BOD removed, mgA
      r

    i.  Estimate effluent BOD  .
                                       /    BOD
                                  = s  i-    r
                               ff          100
                              eff      \
where
      S  =  influent BOD  , mg/£
       o               5

     BOD  =  BOD  removed, percent
       r

     j.  Determine  nutrient  requirements  for  nitrogen



                               N  =  0.123AX^


 and phosphorus



                               P  =  0.026AXy


 where


     AX^ =  sludge produced,  Ib/day


 and check  against rule of thumb  BOD:N:P = 100:5:1-


     k.   Determine recycle ratio  required and check against 0.25-1.0.
                                      X
                                       ac
                                   X   - X
                                    as    ac
                                  7-159

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EM 1110-2-501
Part 1 of 3

  29 Sep 78
where


     Qp = volume of recycled sludge, mgd
      Q = total flow, mgd


    Xac = MLSS in contact tank, mg/£


    Xas = MLSS in stabilization tank,  mg/£


7-55.   Output Data.


    a.   Aeration Tank.


     (1)  Ib BOD/lb  MLSS-day.


     (2)  Mixed liquor  SS contact  tank, mg/£  (MLSS).


     (3)  Mixed liquor  SS stabilization tank, mg/£  (MLSS)


     (k)  Aeration time contact  tank,  hr  (t  ).
                                          c

     (5)  Aeration time stabilization  tank, hr  (t  ).
                                                s

     (6)  Volume  of  contact tank, million gal (V ).


     (7)  Volume  of  stabilization tank, million gal (V  ).


     (8)  Oxygen  required, Ib/day.


     (9)   Sludge  produced, Ib/day.


    (10)   Nitrogen requirement, Ib/day.


    (11)   Phosphorus requirement, Ib/day.


    (12)   Sludge recycle ratio, percent.


    (13)   Volumetric loading, Ib BOD/million ft3


   to.  Diffused Aeration System.


    (1)  Standard transfer efficiency,  percent.




                                7-160
s

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                                                           EM 1110-2-501

                                                             Part  1  of  3


                                                                 29  Sep 78
    (2)   Operating efficiency,  percent.



    (3)   Required air flow,  cfm/1000 ft  .



    c.   Mechanical Aeration  System.



    (1)   Standard transfer efficiency, lb  02/hp-hr.



    (2)   Operating transfer  efficiency,  l"b Og/hp-hr.



    (3)   Horsepower required.



7-56.   Example Calculations.



    a.   Assume the following design parameters.



    (l)   Aeration time in contact tank,   t.^ = 0.6 hr.



    (2)   Aeration time in stabilization  tank,  t^ = 3.0 hr.



    (3)   MLSS in stabilization tank,  X   = 6000 mg/£.
                                       £lS


    (U)   MLSS in contact tank,  X   = 3000 mg/&.
                                 Q,C


    (5)   MLVSS in contact tank,  X^ = O.TXac = 2100 mg/fc.



    (6)  MLVSS in stabilization tank,  Xys = 0.7X&s = ^200 mg/A.



    (7)  0  requirements, 1.3 lb 02/lb BODr.



    (8)  Sludge produced, 0.3 lb solids/lb



    b.  Determine contact tank volume.
                             Vc = QavgV2T


where



      V  = volume contact tank, million gal
       c


         = average  flow, 1.0 mgd
      avg


      t  =  detention time,  0.6  hr
                                  7-161

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 EM 1110-2-501

 Part 1 of 3


  29 Sep ~78
                             v  =
                              c
                            =  0.025 million gal
     c.  Determine  stabilization tank volume.




                             v  = Q    ( -
                              s   ^avg \ 2


where



      Vs = volume  stabilization tank, million gal



     Q    = average flow, 1.0 mgd



      t  = detention time, 3.0 hr
                         V  =0.125 million gal
                          S
    d.  Calculate system organic loading (F/M = 0.2-0.6).




                                       Q   (S )

                     (F/M)
                         '
                          system   V (X  )  + V (X  )
                                    c  vc'     sv  vsy


where



                = system organic loading



            a   = average flow,  1.0 mgd



             SQ = influent BOD , 200 mg/£



             VG = volume of contact tank, 0.025 million gal



            XTC = MLVSS in contact tank, 2100 mg/£






                                 7-162

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                                                           EM 1110-2-501
                                                             Part 1 of  3
                                                                 29 Sep 78
      V  = volume of stabilization tank, 0.125 millron gal
       s

     X   = MLVSS in stabilization tank, 1+200 mg/Ji


                 (F/M)       - 	1^(200
                      system   0.025(2100) + 0.125(^200)


                        (F/M)system= °-3^6 (°K)


    e.  Calculate volumetric loading and check against 60-75 lb/
1000 ft3.

                                 ,   Q   (S )(62.U)
                       lb/1000 ft3 =  avg  °	
                                      (vc + vs)io3

where

    Q    = average flow, 1.0 mgd

      S  = influent BOD, 200 mg/&

      V  = volume of contact tank, 0.025 million gal

      V  = volume of stabilization tank, 0.125 million gal
       S


                lb/1000 ft3 =   1.0(200)(62.10
                              (0.025 + 0.125)103

                lb/1000 ft3 = 83.2, slightly high but OK
    f.  Calculate system oxygen required and select 1.25-1.5 lb 00/
      I
      r
lb BOD .                                                          2
                     02 = (1.25 to 1-5)Q   (Sr)8.3U
where

      0  = oxygen required, Ib/day


                                 7-163

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 EM 1110-2-501
 Part  1  of  3
   29 Sep 78
     Qa   = average flow, 1.0 mgd

      S^ = BOD removed  (200 - 10), 190 mg/£

      02 = 1.3(1. 0)190(8. 3U)


                            0  = 2060 Ib/day
    g.  Design aeration system (diffused).

    (l)  Assume the following parameters.

    (a)  STE =5.0 percent

    (b)  a = 0.9

    (c)  3 = 0.9

    (d)  p = l.O

    (2)  Select summer operating conditions (T = 25°C) and determine 0
saturation.


                             (cj  = 8.2 mg/£



    (3)  Adjust standard transfer efficiency to operating conditions.
              OTE = STE


where

      OTE = operating transfer efficiency, percent

      STE = standard transfer efficiency, 5 percent


    (Cs)  = °o saturation at T = 25°C, 8.2 mg/Jl
        T
        3 = 0.9



                                 7-164

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                                                           EM 1110-2-501

                                                             Part  1 of  3

                                                               29  Sep  78
       p = 1.0



      C  = minimum dissolved oxygen concentration,  2.0 mg/£
       L


    9.17 = 0  saturation at 20°C



       a = 0.9



       T = 25°C




              OTE = 5.0 [8.2(0.9)1.0-2.0]  0.9(1.02)25-20

                                y • •>-1




                               OTE = 2.9$
    (4)  Calculate required airflow.



                                0?(105)7.48

                      R  =	
                       a   OTE(0.0176)l440(V)lO


vhere                                     _

        R  = required airflow, cfm/1000 ft
         El


        0  = oxygen required, 2060 Ib/day



       OTE = operating transfer efficiency, 2.9 percent



    0.0176 = Ib 02/ft3 air



         V = (V  + V ) = 0.15 million gal
               s    c



                      _  _      2060(10^)7.48	
                      n  — 	
                       a   2.9(0.0176)1440(0.15)106
                          R  = 140 cfm/1000 ft3
                           a
    h.  Determine sludge production.  Select (0.2-0.4) Ib solids/
Ib BOD
      r'
                            = (0.2-0.4)Q(Sr)8.34
                                 7-165

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  EM 1110-2-501

  Part 1 of 3

     29 Sep 78


  where



      AXV = sludSe Production,  Ib/day


        Q = average flov,  1.0 mgd


       Sr = BOD  removed, 190 mg/£
                            = 0.3(1.0)(190)(8.34)



                             AXy = U75 Ib/day
     i.  Estimate effluent BOD .



                         /    \        /    BOD
                         (BOD )    = S (l	2
                         V   5/eff    °\    100


 where



     (BOD )    = effluent  BOD

           eff               5

            So = influent  BOD^, 200 mg/H


               = BOD  removed,
                          (BOD )    = 10 mg/£
                          v   •''eff
    J.  Determine nutrient requirements for nitrogen



                         N = 0.123AX



                         N = 0.123(475 Ib/day)


                         N = 58.4 Ib/day


for phosphorus




                                 7-166

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                                                           EM 1110-2-501

                                                             Part 1 of 3


                                                                29 Sep 78



                         P = 0.026 AXy



                         P = 0.026(475 Ib/day)



                         P = 12.4 Ib/day



             N in influent = 30 mg/£(Q   )8.3^
                                      £LV£>


                           = 30(1.0)8.31*



                           = 250 Ib/day >58.U



             H to be added = none



                   P in influent = 15 mg/Jl(Q   )8.3^



                                 = 15(1.0)8.3*t



                                 = 125 Ib/day >12.H



                   P to be added = none



    k.  Determine recycle ratio and check against (0.25-1.0).





                             Q       X
                              r       ac
                                  X   - X
                                   as    ac
where
     Q  = sludge recycle, mgd



      Q = average flow, 1.0 mgd



    X   = MLSS in contact tank, 3000 mg/£
     ac


    X   = MLSS in stabilization tank, 6000 mg/£
     as
                                    3000
                             _

                           1.0   6000 - 3000
                                Qr = 1.0
                                 7-167

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 EM 1110-2-501
 Part  1  of  3
   29  Sep 78

 T-57-   Cost Data.  Appropriate cost data and economic evaluation may be
 found in Chapter 8.

 7-58.   Bibliography.

    a.  American Public Health Association, American Society of Civil
 Engineers, American Water Works Association, and Water Pollution Control
 Federation, "Glossary, Water and Waste-water Control Engineering," 1969.

    b.  American Public Works Association, "Feasibility of Computer
 Control of Wastewater Treatment," Report No. 17090DOY, Dec 1970, U. S.
 Environmental Protection Agency, Washington, D. C.

    c.  American Society of Civil Engineers and the Water Pollution
 Control Federation, "Sewage Treatment Plant Design," Manual of Practice
 No. 8, 1959, 1961, 1967, and 1968, Water Pollution Control Federation,
 Washington, D. C.

    d.  Bargman, R. D. and Borgerding, J., "Characterization of the
 Activated Sludge Process," Report No.  R2-73-22^, Apr 1973, U. S. Envi-
 ronmental Protection Agency, Washington, D. C.

    e.  Busch, A. W., Aerobic Biological Treatment of Wastewaters,
 Oligodynamics Press, 1971.

    f.  Center for Research, Inc., University of Kansas, "Oxygen Con-
 sumption in Continuous Biological Culture," Report No.  17050DJS, May
 1971, U. S. Environmental Protection Agency, Washington, D. C.

    g.  City of Austin, Texas, "Design Guides for Biological Wastewater
 Treatment Processes," Report No.  11010ESQ, Aug 1971, U.  S. Environmental
 Protection Agency, Washington, D. C.

    h.  Eckenfelder, W. W., Jr.,  Industrial Water Pollution Control,
McGraw-Hill, New York, 1966.     ~~~

    i.  Eckenfelder, W. W., Jr.,  "General Concepts of Biological Treat-
ment," Manual of Treatment Processes,  Vol 1, 1969, Environmental Science
 Services, Inc., Briarcliff Manor, New York.

    j.  Eckenfelder, W. W., Jr.,  Water Quality Engineering for  Prac-
ticing Engineers, Barnes and Nobel,  New York, 1970.
                                 7-168

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                                                           EM 1110-2-501
                                                             Part ]  of 3
                                                               29 Sep 78

    k.  Eckenfelder,  W.  W. ,  Jr., "Activated Sludge and Extended Aera-
tion," Process Design in Water Quality Engineering - New Concepts and
Developments, 1971, VanderMlt University, Nashville, Tenn.

    1.  Eckenfelder,  W.  W.,  Jr., and Ford, D.  L.,  Water Pollution
Control, Pemberton'Press, New York, 1970.

    m.  Eckenfelder,  W.  W.,  Jr., and O'Connor, 0.  J., Biological Waste
Treatment, Pergamon Press, New York, 1961.

    n.  Gaudy, A. G., Jr., and Gaudy, E. T., "Biological Concepts for
Design and Operation of the Activated Sludge Process," Report No. 17090-
FQJ, Sep 1971, U. S.  Environmental Protection Agency, Washington, D. C.

    o.  Goodman, B. L. ,  Design Handbook of Wastewater Systems:
Domestic, Industrial, Commercial, Technomic, Westport, Conn., 1971.

    p.  Goodman, B. L. and Englande, A. J., Jr., "A Consolidated
Approach to Activated Sludge Process Design," Conference on Toward a
Unified Concept of Biological Waste Treatment Design, 5-6 Oct 1972,
Atlanta, Ga.

    q..  Lawrence, A. W.  and McCarty, P. L. , "Unified Basis for Biolog-
ical Treatment Design and Operation," Journal, Sanitary Engineering
Division, American Society of Civil Engineers, Vol 96, SA3, 1970.

    r.  Maier, W. J., "Biological Removal  of Colloidal Matter from
Wastewater," Report No.  R2-73-1^7, Jun 1973, U. S. Environmental Pro-
tection Agency, Washington, D.  C.

    s.  McKinney, R. E., Microbiology for  Sanitary Engineers, McGraw-
Hill, New York, 1962.

    t.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection,
Treatment,  and Disposal, McGraw-Hill, New  York, 1972.

    u.  Okun, D. A.,  "System of Bio-Precipitation of Organic Matter  from
Sewage," Sewage Works Journal,  Vol  21, No.  5, 19^9, PP 763-79^-

    v.  Smith, H.  S., "Homogeneous  Activated  Sludge Principles  and
Features of the Activated Sludge Process," Water and Wastes Engineering,
Vol k,  Jul  1967, PP 1*6-50.
                                 7-169

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 EM 1110-2-501
 Part  1  of  3
   29  Sep 78

    w.  Smith, R. and Eilers, R. G.,  "A Generalized Computer Model for
 bteady-State Performance of the Activated Sludge Process  " FWQA Re-
 port  No. TWRC-15, Oct 1969, Robert A. Taft Water Research Center, Cin-
 cinnati, Ohio.

    x.  Stensel, H. D. and Shell, G. L., "Two Methods of Biological
 Treatment Design," Journal, Water Pollution Control Federation  Vol U6
 Feb 1974, PP 271-283.                         ~	'

    y.  Stewart, M. J., "Activated Sludge System Variations - Specific
Applications,  The 15th Ontario Industrial Waste Conference, 9-12 Jun
1968, Niagara Falls, Ontario.

    z.  Toerber, E. D., "Full Scale Parallel Activated Sludge Process
Evaluation," Report No. R2-72-065,  Nov 1972, U.  S.  Environmental Pro-
tection Agency, Washington, D.  C.

    aa.   Weston, R. P., "Design of Sludge Reaeration Activated Sludge
Systems,  Journal, Water Pollution  Control Federation. Vol 33  No  7
1961,  pp 748-757.           "   '                  ~	'        '    '   '
                               7-170

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                                                          EM  1110-2-501
                                                            Part  1  of  3
                                                                 29  Sep 78
                Section IX.   PURE OXYGEN ACTIVATED  SLUDGE
7-59.   Background.
    a.
        As early as 19^9, Okun (para 7-66w)  reported the results  of
tests using pure oxygen as a substitute for  air in the activated  sludge
process.

    "b.  The pure oxygen system may "be used for aeration in activated
sludge systems that operate in either the plug flow or complete mix
hydraulic regimes.  It is readily adaptable  to new or existing complete
mix systems and can be used to upgrade and extend the life of over-
loaded plug-flow systems.  To use the pure oxygen system, the aeration
tanks must be covered and the oxygen introduced should be recirculated
(para 7-66a).  The amount of oxygen that can be injected into the liquid
(for a specific set of conditions) is approximately four times the
amount that could be injected with an air system.  Adjustment of  pH may
be necessary to maintain a proper balance between the C02 removed and
buffer capacity of the wastewater.

    c.  Several advantages, such as increased bacterial activity, re-
duced aeration tank volume, decreased sludge volume, and better settling
sludge have been cited for pure oxygen aeration  (para 7-66a).  To sub-
stantiate these findings, however, further testing of this process in
a number of varying applications will be necessary.  Several references
(o, u, and w, para 7-66) discuss the characteristics and application of
pure oxygen aeration.

7-60.  Input Data.

    a.  Wastewater Flow  (Average and Peak).  In  case of high variability,
a statistical distribution should be provided.

    b.  Wastewater Strength.

     (l)  BOD   (soluble and total), mg/£.

     (2)  COD and/or TOC  (maximum and minimum), mg/£.

     (3)  Suspended solids, mg/£.

     (k)  Volatile  suspended  solids  (VSS), mg/£.

     (5)  Nonbiodegradable  fraction  of  VSS, mg/£.


                                  7-171

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 EM 1110-2-501
 Part 1 of 3
   29  Sep  78

     c.  Other Characterization.

     (1)   PH.

     (2)   Acidity and/or  alkalinity, mg/£.

     (3)   Nitrogen,  mg/£.

     (*0   Phosphorus  (total and soluble), mg/2,.

     (5)   Oils  and greases, mg/£.

     (6)  Heavy metals, mg/£.

     (T)  Toxic or special characteristics  (e.g., phenols), mg/£,

     (8)  Temperature, °F or °C.

    d.  Effluent  Quality Requirements.

     (1)  BOD5, mg/£.

     (2)  SS, mg/£.

     (3)  TO, mg/£.

    (4)  P, mg/£.

    (5)  Total nitrogen (TKN + NO -N), mg/X,.

    (6)  Settleable  solids,  mg/£.

T-6l.  Design Parameters.

    a.   Reaction rate constants  and coefficients.
   The form of nitrogen should be specified as  to  its  biological
  availability (e.g.,  NH  or  Kjeldahl).
                                7-172

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                                                       EM 1110-2-501
                                                         Part 1 of 3

                                                            29 Sep 78
            Constants          _ Range _


           McKinney


              K                   15/hr  at 20°C
               m

              K                lO.U/hr  at 20°C
               s

              K                 0-.02/hr  at 20°C
               e

           Eckenfelder


              k                 O.OOOT-0.002 £/mg/hr


              a                 0.73


              a1                0.52


              b      •           0.075/day


              b'                0.15/day


               f                0.1*0


               f                0.53


b.  F/M = (0.25-1.0).


c.  Volumetric loading = 150-200.


d.  t = (2-1*) hr.

e.  t  =  (3-20) days,  depending on application.
     s

f.  MLSS  = (1*000-7000) mg/£,  mean 5000  mg/i.


g.  MLVSS =  (3200-5600) mg/A.


h.  Q /Q  = (0.25-0.5)  = recycle ratio.
 i.   Ib  0  /l"b  BOD^ = 1.0-1.5 lb.


 J.   lb  solids/lb BOD  = (0.3-0.1*5).
                              7-173

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EM 1110-2-501

Part 1 of 3

  29  Sep  78


    k.  9 =  (1.0-1.03).



    1.  Efficiency = (>90 percent).



7-62.  Design Procedure.



    a.  McKinney's Approach.



    (l)  Assume the following design parameters.



    (a)  Metabolism constant (K ).
                               m


    (b)  Synthesis factor (K ).
                            s


    (c)  Endogenous respiration factor (K ).



    (d)  Temperature correction coefficient (0).



    (e)  Hydraulic detention time (t).



    (f)  Solids retention time (t ).
                                 s


    (2)  Adjust metabolism constant, synthesis factor, and endogenous

respiration factor for temperature.
                            KT - K20
0(T-20)
where
     K  = rate constant at desired temperature T, °C



    K   = rate constant at 20°C



      0 = temperature coefficient



      T = temperature, °C



    (3)  Determine size of the aeration tank.

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                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                                 29 Sep 78
where



       V = volume of tank, million gal



    Q    = average flow, mgd
     avg


       t = hydraulic detention tine, hr



    (h)  Determine soluble effluent BOD .




                                    F.
                             Fe ~ 1 + K t
                                       m
where
    F  = soluble effluent BOD  , mg/fc
     e                       5


    F. = influent BODC, mg/£
     i               5


    K  = metabolism constant (15/hr at 20°C)
     m


     t = hydraulic detention time, hr
 and  check  F  < 10 mg/£  ; if  F  > 10 mg/Jl  , increase  t  and recalcu-
            6 —                G
 late new  F
           e


     (5)  Calculate the MLSS concentration.






                    ^T ~ a    e     i     ii



                            K F

                    M =
                      a   K  +  l/2Ut
                           e        s
                     M  =  0.2K M t  (2U)
                      e       e a s
                     M.  = SS.  x
                      .      .
                      i      it
                     M..  = SS. .  x —-§. + o.l(M  + M )
                      11      11     t          a    e
                                  7-175

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M 1110-2-501

Part 1 of 3

  29 Sep  78




where




      M  = total mass, mg/£




      M  = living, active mass, mg/£
       cL



      M  = endogenous mass, mg/£




      M. = inert nonbiodegradable organic mass, mg/X,




     M.. = inert inorganic suspended solids, mg/X,




      KS = synthesis factor, 1/hr (lO.Vhr at 20°C)




      Fg = effluent BOD  , mg/X,




      Kg = endogenous respiration factor, 1/hr  (0.02/hr at 20°C)




      t  = solids retention time, days
       S



     SS.^ = inert organic SS in influent, mg/£




         = VSS x percent nonbiodegradable (f*Q.h VSS for municipal waste)




    SSi:L = inert inorganic SS fraction in the influent




and check  MT  against 4000-7000 mg/£; vary  t   or  t  until  M   falls

within desired range.                         s




    (6)  Check organic loading against 0.25-1.0.






                               F/M = —r-




where




    F/M = food-to-microorganism ratio




     F± = influent BOD , mg/£




     M  = total mass, mg/£




      t = hydraulic detention time,  hr








                                 7-176

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                                                            EM 1110-2-501

                                                              Part  1 of 3

                                                                  29 Sep 78


    If F/M < lower limit, it  is possible to  reduce   t   and  recalculate

MT  •


    If F/M > upper limit, increase  t  and recalculate  M   .



    (7)  Calculate the oxygen requirements.



    (a)  Select the oxygen uptake rate.  The average rate of  oxygen

demand, if the waste load is uniform, is given by
                   dO

                   dt
where
    dO/dt = average oxygen uptake rate under uniform flow

            conditions, mg/£



       F  = influent BOD  , mg/£



       F  = soluble effluent BOD  , mg/£



        t = hydraulic detention time, hr



       M  = living, active mass, mg/£
        3d


       M  = endogenous mass, mg/£



       t  = solids retention time, days
        S


Under conditions where the load varies, the oxygen uptake is equal to

the synthesis oxygen demand plus the endogenous respiration oxygen

demand or
                  dO
                  — = I	::— I —£:— +1 i UK M
                  -ii    I      i        l^-i    i  _L » _L H- IV 1¥1
                  dt   L     t      J Q           e a
                                       avg
                        Ib 0_/hr =    x v
                            i—      ClO
where



      Q  = peak flow, mgd




                                 7-177

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EM 1110-2-501
Part 1 of 3
   29 Sep 78

    Q    = average flow, mgd

      K  = endogenous respiration factor, hr (0.02/hr at 20°C)

    (b)  Check oxygen supplied per pound of BOD removed >1.25.


                             Ib 02/hr (2k)
                             Q(F. - F )8.3U


    (8)  Design aeration system and check horsepower for complete mix-
ing against horsepower required for complete mixing >_0.1 hp/1000 gal;
select the larger horsepower.

    (a)  Diffused Aeration System.

    !_  Assume the following design parameters.

    a_  Standard transfer efficiency, percent, from manufacturer.

    b_  0  transfer in waste/09 transfer in water asO.9.

    c_  0  saturation in waste/0  saturation in water asO.9-

    d_  Correction factor for pressure %L.O.
    2_  Select summer operating temperature (25-30°C) and determine  (from
    .dard tables) 0  saturation.

    3_  Adjust standard transfer efficiency to operating conditions.
                OTE = STE ^	x     	- a(l.02)T 2°


where

      OTE = operating transfer efficiency, percent

      STE = standard transfer efficiency, percent

    (C \  = 0  saturation at selected summer temperature T, °C, mg/£
    V s /_    c.


                                 7-178

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                                                            EM 1110-2-501
                                                              Part  1 of 3
                                                                 29 Sep 78
         3=0   saturation in waste/0?  saturation  in  water ssO.9

         p = correction factor  for pressure ^L.O

       C = minimum dissolved  oxygen to be maintained  in the  basin
            > 2.0 mg/H

         a = 0   transfer in waste/0  transfer in water  asO.9

         T = temperature, °C

    ^_  Calculate required air  flow.
                       R  =


where

     R  = required air flow, cfm/1000 ft
      cl

     0  = oxygen required, Ib/day

    OTE = operating transfer efficiency, percent

      V = volume of basin, gal

     CF = correction factor, Ib 0 /ft  air

    (b)  Mechanical Aeration System.

    1_  Assume the following design parameters.

    a_  Standard transfer efficiency, Ib/hp-hr (0 dissolved oxygen, 20°C,
and tap water).

    b_  0  transfer in waste/0  transfer in water 5*0.9.

    c_  Og saturation in waste/0  saturation in water «s0.9.

    cl  Correction factor for pressure «1.0.

    2_  Select summer operating temperature (25-30°C), and determine
(from standard tables) 0  saturation.


                                 7-179

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EM 1110-2-501

Part 1 of 3

   29 Sep 78


    3.  Adjust standard transfer efficiency to operating conditions.
                          I  \  / rn          -"I        m on
                OTE - STE		 a(l.02r~dU



where



      OTE = operating transfer efficiency, Ib 0 /hp-hr



      STE = standard transfer efficiency, Ib 0 /hp-hr



      „)  = 0  saturation at selected summer temperature T, °C, mg/£



        g = 00 saturation in waste/0  saturation in water adO.9



        p = correction factor for pressure sal.O



       C  - minimum dissolved oxygen to be maintained in the basin

            > 2.0 mg/£



        a = 0  transfer in waste/0p transfer in water ssO.9



        T = temperature, °C



       Calculate horsepower requirement.




                                  °2
                     hp =	TT-^	 x 1000
where



     hp = horsepower required/1000 gal



     0_ = oxygen required, Ib/day



    OTE = operating transfer efficiency, Ib 0 /hp-hr



      V = volume of "basin, gal



    (9)  Calculate sludge production and determine pounds of sludge

wasted per day.




                                 7-180

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                29  Sep 78
where

    AM  = sludge produced, Ib/day

     1VL - total mass, mg/£

      V = volume of aeration tank, million gal

     t  = solids retention time, days
    (10)  Check solids produced per pound of BOD removed.


                       Ib solids _      AMT	
                        Ib BOD     Q(F.  - F )Q.3k
                              r       i     e
where

    AM  = sludge produced, Ib/day

      Q = flow, mgd

     F. = influent BOD , mg/Jl

     F  = effluent BOD , mg/£

    (ll)  Calculate sludge recycle ratio.
                              5r
                              Q
where
    Q  = volume of recycled sludge, mgd

     Q = flow, mgd

    M  = total mass, mg/£

    M  = solids concentration in return sludge,  mg/£
                                 7-181

-------
EM 1110-2-501
Part 1 of 3
  29  Sep  78
    (12)  Calculate total effluent BOD .
                                             /M \
                      ,eff - °e * °-*
-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                29 Sep 78

    (e)  Mixed liquor suspended solids (MLSS).

    (f)  Mixed liquor volatile suspended solids (MLVSS).

    (g)  Food-to-microorganism ratio (F/M).

    (h)  Nonbiodegradable fraction of VSS in influent (f).

    (i)  Degradable fraction of the MLVSS (f).

    (j )  Temperature correction coefficient (0).

    (2)  Adjust rate constant for temperature.


                                 K  Q(T-20)


where

     K  = rate constant at desired temperature, °C

    K   = rate constant at 20°C

      0 = temperature correction coefficient

      T = temperature, °C

    (3)  Determine the size of the aeration tank  by first determining
the detention time  t .


                             t =
                                 (XV)(F/M)

where

      t = detention time, hr

     S  = influent BOD, mg/'£

     Xy = MLVSS, mg/£

    F/M = food-to-microorganism ratio

    (h)  Check detention time for treatability.

                                 7-183

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EM 1110-2-501
Part 1 of 3
29 Sep 78
                             fe
                             So
vhere
    S  = BOD  (soluble) in effluent, mg/£

    S  = BOD  in influent, mg/fc

     k = BOD removal rate constant, 1/mg/hr

    Xy = MLVSS, mg/H

     t = detention time, hr

Solve for  t  and compare with  t  'above and select the larger.

    (5)  Calculate the volume of aeration tank.

                                        t
                                 ^avg   2^

vhere

       V = volume, million gal

    Q    = average daily flow, mgd

       t = detention time, hr

    (6)  Calculate oxygen requirements.
                            dt    t
or


               °2= a'(Sr)(Qavg)(8-3l° H

where

    dO/dt = oxygen uptake rate, mg/£/hr



                                 7-18U

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                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                              29  Sep  78
       a' = fraction of BOD oxidized for energy



       S  = BOD removed (S  - S  ), mg/Jl



        t = detention time, hr



       b' = endogenous respiration rate, 1/hr



       Xy = MLVSS



       0  = oxygen requirement, Ib/day



     Q    = average flov rate, mgd
      avg


        V = volume of aeration tank, million gal



and check the oxygen supplied against >_1.25




                                           °2
                      Ib 00/lb BOD  =
                                  r ~ Q(Sr) x 8.3^


where



    0  = oxygen required, Ib/day



     Q = flow, mgd



    S  = BOD removed, mg/£



    (T)  Design aeration system and check horsepower supply for mixing

against horsepower required for complete mixing <_0.1 hp/1000 gal.



    (a)  Diffused Aeration System.



    ~L_  Assume the following design parameters.



    a_  Standard transfer efficiency, percent, from manufacturer.



    b_  0  transfer in waste/0? transfer in water ssO.9.



    £  0  saturation in waste/0  saturation in water «0.9.



    
-------
EM 1110-2-501
Part 1 of 3
 29 Sep 78

    2_  Select summer operating temperature (25-30°C) and determine
(from standard tables) Q  saturation.

    3_  Adjust standard transfer efficiency to operating conditions.
                          [(c.)
OTE = STE	i——	 a(l.02)T~2°
where

      OTE = operating transfer efficiency, percent

      STE = standard transfer efficiency, percent

    (C )  = 0  saturation at selected summer temperature T, °C, mg/£

        3 = 0  saturation in waste/0  saturation in water ssO.9

        p = correction factor for pressure sj_.0

       C  = minimum dissolved oxygen to be maintained in the basin
            > 2.0 mg/£

        a = 0  transfer in waste/0  transfer in water saO.9

        T = temperature, °C

    H_  Calculate required air flow.

                               0
                       R  =
                                 ,
                            (OTE)fl^O

where

     R  = required air flow, cfm/1000 ft
      3*

     0  = required oxygen, Ib/day

    OTE = operating transfer efficiency, percent

      V = volume of basin, gal

     OF = correction factor, Ib 0 /ft  air


                                7-186

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78

    (b)  Mechanical Aeration System.

    1_  Assume the following design parameters.

    a_  Standard transfer efficiency, Ib/hp-hr (0 dissolved oxygen, 20°C,
and tap water.

    b_  0  transfer in waste/0  transfer in water ajO.9-

    c_  0  saturation in waste/0  saturation in water stQ.9-

    d_  Correction factor for pressure %1.0.

    2_  Select summer operating temperature (25°C-30°C) and determine
(from standard tables) 0  saturation.

    3_  Adjust standard transfer efficiency to operating conditions.

                                           1
                                       - CT
where
                                          L
                OTE = STE *-'   T     	=1 a(l.02)T~2°
                                 y • -L /
      OTE = operating transfer efficiency, Ib 0 /hp-hr

      STE = standard transfer efficiency, Ib 0 /hp-hr

    /C ^  = 0_ saturation at selected summer temperature T, °C, mg/£
    \ S/T    2
        3=0  saturation in waste/0  saturation in water «O.9

        p = correction factor for pressure a=1.0

       C  = minimum dissolved oxygen to be maintained in the basin
            > 2.0 mg/£

        a = 0  transfer in waste/0  transfer in water

        T = temperature, °C

    h  Calculate horsepower requirement.
                                 7-187

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EM 1110-2-501

Part 1 of 3

 29  Sep  78
                                              100°
where


     hp = horsepower required/1000 gal



     0  = oxygen required, l"b/day



    OTE = operating transfer efficiency, Ib 02/hp-hr



      V = volume of basin, gal



    (8)  Calculate sludge production.



           AX, =  [aS Q    - bX V + fQ(VSS) + Q(SS - VSS)]8.3^
             T    L  r avg     v



where


     AX  = sludge produced, Ib/day


       a = fraction of  BOD removed synthesized to cell material



       S  = BOD removed, mg/£
       r


    0    = average flow, mgd
     avg


       b = endogenous respiration rate/day


       X^ = volatile  solids  in raw sludge,  mg/X,



       V = volume of basin, gal


       f = nonbiodegradable fraction of influent VSS



        Q =  flow, mgd


      VSS =  volatile suspended solids in effluent, mg/£



       SS =  suspended solids in influent, mg/£



     (9)   Check  AX.^  against  0.3-0.1+5.



                                  7-188

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                                                           EM 1110-2-501

                                                             Part  1  of  3

                                                               29  Sep 78
                        Ib solids =     AXV

                            BODr)   Sr(Q)(8.3M
where



    AX^ = sludge produced, Ib/day



     S  = BOD removed, mg/'H
      r


      Q = flow, mgd



    (10)  Calculate sludge recycle ratio.
                              Q      X
                               r      a
                                   X  - X
                                    u    a
where
    Q /Q = sludge recycle ratio



      Q  = volume of recycled sludge, mgd



       Q = flow, mgd



      X  = MLSS, mg/H
       a


      X  = solids concentration in return sludge, mg/£
       u


    (11)  Calculate solids retention time.



                                 (V)X (8.310

                           SRT = -
                                     AX
                                       a


 where



     SRT = solids retention time, days



                                     AX
                            AX  =
                              a   % volatile
                                 7-189

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78

    (12)  Calculate effluent BOD  .
                      BOD      = S  + 0.81*
where

         Sg = effluent soluble BOD, mg/£

    (\ )    = effluent volatile suspended solids, mg/£
    x v/eff
         f '  = degradable fraction of MLVSS

    (13)  Determine nutrient requirements for nitrogen


                          N =

and phosphorus


                          P = 0.026AMT(or


where

    AM  = sludge produced, l"b/day

    AX^ = sludge produced, l"b/day

and check against BOD:N:P = 100:5:1.

7-63.   Output Data.

    a.   Aeration Tank.

    (l)   Reaction rate  constant,  1/mg/hr.

    (2)   Sludge produced per BOD  removed.

    (3)   Endogenous  respiration rate  (b,  b').

    (k)   0  = utilized  per BOD removed.

    ( 5 )   Influent nonbiodegradable VSS ( f ) .

                                 7-190

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                                                       EM 1110-2-501
                                                         Part 1 of 3
                                                           29 Sep 78
  (6)   Effluent  degradable VSS  (f).

  (7)   Ib  BOD/lb MLVSS-day (F/M ratio).

  (8)   Mixed  liquor  SS, mg/£  (MLSS).

  (9)   Mixed  liquor  VSS, mg/£  (MLVSS).

 (10)   Aeration  time,  hr.

 (11)   Volume of aeration tank, million gal.

 (12)   Oxygen required, Ib/day.

 (13)   Sludge produced, Ib/day.

 (lU)   Nitrogen  requirement,  Ib/day.

 (15)   Phosphorus  requirement,  Ib/day.

 (l6)   Sludge recycle  ratio,  percent.

 (IT)   Solids retention time,  days.

 b.   Diffused Aeration System.

 (l)   Standard transfer efficiency, percent.

 (2)   Operating  transfer efficiency, percent.

 (3)   Required air flow, cfm/1000  ft3.

 c.   Mechanical  Aeration System.

 (1)   Standard transfer efficiency, Ib  0  /hp-hr.

 (2)   Operating  transfer efficiency, Ib 0 /hp-hr.

 (3)   Horsepower required.

k.   Ey Jiple Calculations.  Eckenfelder's  Approach.

 a.   Assume the  following design parameters.


                             7-191

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EM 1110-2-501

Part 1 of 3

 29 Sep 78



     (1)  K = 0.0012 £/mg-hr



     (2)  a = 0.73



     (3)  a' = 0.5



     (1+)  b = 0.075/day, b1 = 0.15/day



     (5)  MLSS = X  = 3000 mg/£
                  cl


     (6)  MLVSS = Xy = 21+00 mg/£



     (7)  F/M = 0.1+0 lb BOD/lb MLVSS-day



     (8)  f = 0.1+0




     (9)  f = 0.53



    (10)  0 = 1.03



    b.   Adjust the BOD removal rate constant for winter conditions,

T = 15°C.




                             „  _ „  0T-20

                             T1    20


where




     K  = rate constant at temperature T



    K   = rate constant at 20°C, 0.0012 £/mg-hr



      T = temperature, 15°C



      6 = temperature correction coefficient, 1.03






                         K^, = 0.0012(1.03)15~2°




                         K  = 0.0010 £/mg-hr
    c.  Determine size of aeration tank by determining detention time.
                                 7-192

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                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                              29  Sep  78
                              t =
                                  X^F/M)




where



      t = hydraulic detention time, hr



     S  = influent BOD, 200 mg/£
      o


        = MLVSS, 2UOO mgA
    F/M = food-to-microorganism ratio, 0.^0 l"b BOD/lb MLVSS




                                  2U(200)

                                 2UOO(O.UO)




                               t = 5.0 hr



    d.  Check detention for treatability.



                             S       .
                              e      1
                             S    1 +
where
     S  = effluent BOD ..(soluble), 10 mg/£
     e               5


     S  = influent BOD  , 200 mg/&



     K = BOD removal rate constant, 0.001 £/mg/hr



     Xy = MLVSS,  2UOO mg/&



     t = detention time, hr
                          10
                         200    1  +  (O.OOl)2UOQ(t)




                           t=T.9hr>5.0hr



     e.   Calculate the volume of  the  aeration  tank,




                                 7-193

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 EM 1110-2-501
 Part 1 of 3
 29 Sep 78


                               V =

 where

        V  =  volume,  million gal

     Q&   =  average  flow,  1.0 mgd

        t  =  detention  time,  7.9 hr


                           V =  1.
                           V = Q.329 million gal

    f.  Calculate oxygen requirements.


                      °2 =  a'SAvg(8-3l° +

where

      0  = oxygen required, Ib/day

      a' = 0.52

      S^ = BOD removed (S  - S  ), 190 mg/£

    Q&   = average flow, 1.0 mgd

      V = 0.15/day

      Xy. = MLVSS, 2^00 mg/£

       V = volume of aeration tank, 0.329 million gal


             o2 = 0.52(190)1.0(8.3^) + 0.15(21+00)0.329(8.310


                            02 = 1812 lt>/day

Check oxygen supplied per Ib BOD removed >1.25.

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep  78
                 •  °2
Ib 00/lb —
                           2       r - Q(s )8>
                                          r'
where

    0  = oxygen required, 1812 Ib/day
     Q = average flow, 1.0 mgd

    S  = BOD removed, 190 mg/£
                     Ib 02/lb
                      Ib 0Jib BOD  = I.Ik < 1.25

Therefore

                         0  =1.25 BOD
                          P           y1

                         0  = 1.25Q(Sr)8.3^

                         02 = 1.25(1.0)190(8.3U)

                            0  = 1980 Ib/day

    g.  Design aeration system (mechanical surface).

    (l)  Assume the following parameters

         STE = 5.0 percent

           a = 0.9

           3 = 0.9

           p = pressure correction factor, 1.0

    (2)  Select summer operating temperature and determine 0  saturation.
T = 25°C, (CS)T = 8.2 mg/A.

    (3)  Determine operating transfer efficiency.


                                 7-195

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EM 1110-2-501
Part 1 of 3
29 Sep 78
                          [(CB)T*».-CL]
                OTE = STE	—•	 al.02T~20

where

      OTE = operating transfer efficiency, percent

      STE = standard transfer efficiency,  5.0 percent

     (c \  =8.2 mg/£

       CL = minimum dissolved oxygen, 2.0 mg/£

        T = 25°C,  a = 0.9,  B = 0.9

     9-17 = 0  saturation at 20°C


             OTE = 5.0 [8.2(0.9)1.0 - 2.01 0.9(1.02)25-20
                              y • -L I

                        OTE = 2.9% or Ib 0 /hp-hr

     (4)  Calculate horsepower requirements.


                             hp = 	^2	
                                  OTE(24)V
where

     hp = horsepower requirements,  hp/1000 gal

     02 = oxygen required,  1980 Ib/day

    OTE = operating transfer efficiency, 2.9 percent

      V = volume of aeration tank,  0.329 million gal


                        h  _ 	1980	
                             2.9(2100.329(1000)

                 hp =  0.09  hp/1000  gal < 0.1 hp/1000 gal


                                 7-196

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                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                              29  Sep  78
Therefore, use hp = 0.1 hp/1000 gal



                           hp = 0.1(V)1000



                           hp = 0.1(0.329)1000



                          hp = 32.9 hP (use 35



    h.  Calculate sludge production'
- bXy(V) + Qavg(VSS)f + Qayg(SS - VSS)]8.3U
                                   avg




vhere



     AX  = sludge produced, Ib/day



       a = 0.73



      S  = BOD removed, 190 mg/Jl



    Q    =1.0 mgd
     avg


       ID = 0.075/day



      X_^ = 2UOO mgA



       V = 0.329 million gal



     VSS = effluent volatile suspended solids, 150 mg/£



       f = 0.^0



      SS = suspended solids in influent, 200 mg/&




               AX^ = [0.73(190)1.0 - 0.075(2UOO)0.329



                     + 1. 0(150)0. UO + 1.0(200 - 150)]8.3U



                           AX  = 1580 Ib/day
     i.   Calculate  solids produced per pound of BOD  removed and  check

     >  0.5-0.7-




                                7-197

-------
                         Ib solids _    AXV

                          Ib BOD   ~ S
EM 1110-2-501

Part 1 of 3

29 Sep 78
                                      r


where



          AX  = solids produced, 1580 Ib/day



           S^ = BOD removed (S  - S ), 190 mg/£



            Q = average flow,  1.0 mgd



                     Ib solids _     1580

                      Ib BOD     1.90(1.0)8.3lt
                            r
                                       0.5-0.7 (OK)
    j.   Calculate sludge recycle ratio
                              Q      X
                               r      a
                              Q    X  - X
                                    u    a

where
    Q  = volume of recycled sludge,  mgd
     Q = average flow, 1.0 mgd



    X  = MLSS, 3000 mg/£
     a
    X  = return sludge concentration,  10,000 mg/£
                                    3,000
                          1.0   10,000 - 3,000



                             Qr =  O.U29 mgd





    k.   Calculate solids  retention time.
                                  V(X )8.

                            SRT  =     a
                                     AX
                                       a
                                 7-198

-------
where

    SRT = solids retention time, days

      V = volume of aeration tank, 0.329 million gal

     X  = MLSS, 3000 mg/£
      a
    AX  = AXy/^ volatile = 1580/0.80 = 1975 It/day

                             _ 0.329(3000)8.3^
                             SRT = k.2 days

    1.  Calculate effluent BOD  .

                          \     = S  + 0.8U(X  )    f
                          5/eff    e           eff

where
     (BOD      = effluent  BOD  , mg/£
     ^
                      5'
    ii J.
     S  =  effluent soluble BOD^,  10 mg/£
      e                        5
(x. )    =  effluent volatile suspended solids, 20
    P"f>"P
     f  =  0.53

               (BOD )    = 10 + 0.8^(20)0.53
               ^   5/^eff
                    (B°D5)
                                     = 19
                                 eff
     m.   Determine  nutrient requirements for nitrogen

                             N = 0.123AXy.

                             N = 0.123(1580)

                             N = 19k Ib/day



                                  7-199
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                29 Sep 78

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EM 1110-2-501
Part 1 of 3
29 Sep 78

for phosphorus

                            P = 0.026A3C.

                            P = 0.026(1580)

                            P = hi Ib/day

                     N in influent = 30 mg/£(Q   )Q.3k

                                   = 30(1.0)8.3U

                                   = 250 Ib/day > igb Ib/day required

                     N to be added = none

             P in influent = 15 mg/£(Q   )8.3^

                           - 15(1.0)8.3U

                           = 125 Ib/day > la Ib/day required

             P to be added = none

7-65-  Cost Data.  Appropriate cost data and economic evaluation may be
found in Chapter 8.

7-66.  Bibliography.

    a.   Albertsson, G.  G. et al., "Investigation of the Use of High
Purity Oxygen Aeration in the Conventional Activated Sludge Process,"
Water Pollution Control Research Series Report No.  17050DNW, May 1970,
Federal Water Quality Administration, Washington, D. C.

    b.   American Public Health Association, American Society of Civil
Engineers, American Water Works Association, and Water Pollution Control
Federation, "Glossary,  Water and Wastewater Control Engineering," 1969.

    c.   American Public Works Association, "Feasibility of Computer
Control of Wastewater Treatment," Report No. 17090DOY, Dec 1970, U. S.
Environmental Protection Agency, Washington, D. C.
                                7-200

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                                                           EM 1110-2-501
                                                             Part 1 of 1
                                                              29 Sep 78

    d.  American Society of Civil Engineers and the Water Pollution
Control Federation, "Sewage Treatment Plant Design," Manual of Practice
No. 8, 1959, 1961, 196T, and 1968, Water Pollution Control Federation,
Washington, D. C.

    e   Bargman, R. D. and Borgerding, J., "Characterization of the
Activated Sludge Process," Report No. R2-73-22U, Apr 1973, U. S. Envi-
ronmental Protection Agency, Washington, D. C.

    f.  Busch, A. W., Aerobic Biological Treatment of Wastewaters,
Oligodynamics Press, 1971-

    g.  Center for Research, Inc., University of Kansas, "Oxygen Con-
sumption in Continuous Biological Culture," Report No. 17050DJS, May
1971, U. S. Environmental Protection Agency, Washington, D. C.

    h.  City  of Austin, Texas, "Design Guides for Biological Wastewater
Treatment Processes," Report No. 11010ESQ, Aug 1971, U. S. Environmental
Protection Agency, Washington, D. C.

    i.  Eckenfelder, W. W., Jr., Industrial Water Pollution Control,
McGraw-Hill,  New  York, 1966.

    j.  Eckenfelder, W. W., Jr.,  "General  Concepts of Biological Treat-
ment," Manual of  Treatment Processes, Vol  1,  1969, Environmental Science
Services,  Inc., Briarcliff Manor, New York.

    k.  Eckenfelder, W. W., Jr., Water  Quality Engineering for
Practicing  Engineers, Barnes and  Nobel,  New York,  1970.

    1.  Eckenfelder, W. W., Jr.,  "Activated Sludge  and  Extended Aera-
tion," Process  Design in  Water Quality  Engineering -  New  Concepts  and
Developments, 1971, Vanderbilt University, Nashville, Tenn.

    m.  Eckenfelder, W. W., Jr.,  and Ford, D.  L.,  Water Pollution
 Control,  Pemberton Press, New York,  1970.

    n.  Eckenfelder,  W. W., Jr.,  and O'Connor,  0.  J., Biological Waste
 Treatment,  Pergamon Press,  New York, 1961.

     o.  Gaudy,  A. G., Jr.,  and Gaudy, E. T.,  "Biological Concepts  for
 Design and Operation of the Activated Sludge  Process,"  Report No.  17090-
 FQJ,  Sep  1971,  U. S.  Environmental Protection Agency, Washington,  D.  C.
                                 7-201

-------
 EM 1110-2-501
 Part  1 of 3
 29 Sep 78

    p.   Goodman, B.  L. , Design Handbook  of Wastewater Systems:  Domestic
 Industrial,  Commercial, Technomic, Westport, Conn., 1971.

    q..   Goodman, B.  L. and Englande, A.  J., Jr.,  "A Consolidated
 Approach to  Activated Sludge Process Design," Conference on Toward a
 Unified Concept of Biological Waste Treatment Design, 5-6 Oct 1972,
 Atlanta,  Ga.

    r.   Lawrence, A. W. and McCarty, P.  L., "Unified Basis for Biologi-
 cal Treatment Design and Operation," Journal, Sanitary Engineering
 Division, American Society of Civil Engineers, Vol 96, SA3, 1970.

    s.  Maier, W. J., "Biological Removal of Colloidal Matter from
 Wastewater," Report  Wo. R2-73-1^7, Jun 1973, U. S. Environmental Protec-
 tion Agency, Washington, D. C.

    t.  McKinney, R. E., Microbiology for Sanitary Engineers, McGraw-
 Hill, New York, 1962.

    u.  McKinney, R. E. and Pfeffer, J. T.,  "Oxygen-Enriched Air for
 Biological Waste Treatment," Water and Sewage Works, Vol 112, Oct 1965
 PP 381-381*.                                 	

    v.  Metcalf and Eddy, Inc., Wastewater Engineering;  Collection,
 Treatment, and Disposal, McGraw-Hill, New York, 1972.

    w.  Okun, D. A., "System of Bio-Precipitation of Organic Matter
 from Sewage," Sewage Works Journal, Vol 21,  No.  5, 19^9, pp 763-79^.

    x.  Smith, H.  S., "Homogeneous Activated Sludge Principles and
 Features of the Activated Sludge Process," Water and Wastes Engineering,
 Vol k, Jul 1967, pp 46-50.                                      	

    y.  Smith, R.  and Eilers,  R.  G., "A Generalized Computer Model for
 Steady-State Performance of the Activated Sludge Process," FWQA Report
No. TWRC-15,  Oct 1969, Robert  A.  Taft Water  Research Center, Cincinnati,
 Ohio.

    z.  Stensel, H.  D. and Shell, G. L.,  "Two Methods  of Biological
Treatment Design," Journal, Water Pollution  Control Federation,  Vol h6,
Feb 197^» PP 271-283.
                                7-202

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep  78

    aa.  Stewart, M. J.,  "Activated Sludge System Variations - Specific,
Applications," The 15th Ontario Industrial Waste Conference, 9-12 Jun
1968, Niagara Falls, Ontario.

    bb.  Toerber, E. D.,  "Full Scale Parallel Activated Sludge Process
Evaluation," Report Wo.  R2-72-065, Nov 1972, U. S. Environmental Pro-
tection Agency, Washington, D. C.

    cc.  Union Carbide Corporation, "Continued Evaluation of Oxygen Use
in Conventional Activated Sludge Processing," Report No. 17050DNW, Feb
1972, U. S. Environmental Protection Agency, Washington, D. C.

    dd.  Union Carbide Corporation, "Unox System Wastewater Treatment,"
Report of Pilot Study at Hooker's Point Treatment Plant, Tampa, Fla.

    ee.  Weston, R. F., "Design of Sludge Reaeration Activated Sludge
Systems," Journal, Water Pollution Control Federation, Vol 33, No. '7,
1961, pp 7^8-757-
                                  7-203              (next  page is  7-205)

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78

                  Section X.  AERATED AEROBIC LAGOONS

T-6T-  Background.

    The contents of an aerated aerobic lagoon must be completely mixed
so that the incoming solids and the biological solids produced in the
lagoon do not settle.  Effluent quality is a function of the detention
time and will normally have a BOD ranging from one-third to one-half
of the influent value.  This BOD is due to the endogenous respiration
of the biological solids escaping in the effluent.  Before the effluent
is discharged, the solids may be removed by settling.  Where sedimenta-
tion is used, it may be advantageous to provide for recycle.  A schema-
tic of aerated lagoons is shown in Figure 7-8.
                                AEROBIC
                                                    ANAEROBIC
                                                     SLUDGE
                                                    DEPOSITS
                                    b.
                                          From Metcalfand Eddy, 1972

             Figure 7-8.  Schematic  of  (a) an aerated  lagoon
                   and  (b) an aerobic-anaerobic lagoon.

7-68.  Input Data.

    a.  Wastewater Flow.

    (l)  Average daily, mgd.

    (2)  Peak  (hourly), mgd.

    b.  Wastewater Characteristics.

    (l)  BOD influent, mg/£.

                                 7-205

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 EM 1110-2-501
 Part 1 of 3

 29 Sep 78

     (2)  Influent SS, mg/£.

     (3)  Influent VSS, mg/SL.

     (h)  Nitrogen, mg/H.


     (5)  Phosphorus,  mg/£.


     (6)  Nonbiodegradable fraction of VSS.

     c.   Desired degree of treatment,  percent.

     d.   Temperature,  °F or °C  (summer and winter).

 7-69.   Design Parameters.

     a.   McKinney's Approach.


     (1) . Reaction rates:  K   , 15/hr  at 20°C;  K   , lO.Vhr at 20°C-
 and  K   ,  0.02/hr at  20°C.                      s
       e
     (2)  Hydraulic detention time, 2-k days.

     (3)  Solids retention time, 3-7 days.

     (M  MLSS under aeration, 200-500 mg/£.

     (5)  Temperature coefficient, 1.035.

     (6)  Depth, 6-12 ft.

    b.  Eckenfelder's Approach.


     (1)  Reaction rate constant, 0.0007-0.002 1/mg-hr.

     (2)  MLSS, 200-500 mg/A.

    (3)  MLVSS, 1140-350 mg/Ji,.


    (h)  Fraction of BOD synthesized,  0.73.


    (5)  Fraction of BOD oxidized for  energy, 0.52.


    (6)  Endogenous respiration  rate per day (b = 0.075/dav
b' = 0.15/day).

                                 7-206

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep  78

     (T)  Temperature coefficient, 1.035.

     (8)  Hydraulic detention time, 2-k days.

     (9)  Depth, 6-12 ft.

7-70.  Design Procedure.  Most designers choose to treat this type of
lagoon as a variation of an activated sludge process.  Two well-known
systems for design are as'follows.

     a.  McKinney's Approach.

     (l)  Determine size of lagoon.  Select the metabolism constant,
K   , and the detention time,  t  .


                                 V = Qt

where

    V = volume, million gal

    Q = flow, mgd

    t = detention time, days

     (2)  Adjust the metabolism constant for temperature.   Select
temperature correction coefficient.
                              _       fl(T-20)
                           mT " Km(20)0
where
       K   = metabolism constant

    K ,   ,  = rate constant at 20°C

         Q  = temperature correction coefficient

         T = temperature, °C

    (3)   Calculate the effluent BOD  for both winter and summer,



                                7-207

-------
EM 1110-2-501

Part 1 of 3

29 Sep 78
                                     F.
                              F  =
                               e   1 + K t
                                        m
where
    F. = influent BOD , mg/£



    F  = effluent BOD,., mg/£
     e               5
         Calculate the total mass; select the synthesis factor,  K  ,

and the endogenous respiration factor,  K




                    Mm = M  +M  + M. + M. .
                     TO    a    e    i    11
                            K K
                             s e
                     a   K  + 1/2H
                          e        s
                    M  = 0.2K M t (2M
                     e       e a s
                    M. = SS.
                      .      .
                      i      it
                                 2Ut

                    M. . = SS. . x — — £- + 0.1(M  + M  )
                     11     11    t          a    e
where
      M  = total mass, mg/fc



      M  = living active mass, mg/£
       £L


      M  = endogenous mass, mg/£



      M. = inert nonbiodegradable  organic mass, mg/H



     M.. = inert inorganic suspended  solids, mg/£
                                 7-208

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                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                              29 Sep 78



      K •= synthesis factor,  hr (lO.U/hr at 20°C)
       s


      K  = endogenous respiration factor, hr (0.02/hr at 20°C)
       e


      t  = solids retention time, days
       s


     SS. = inert organic SS in influent, mg/£



         = VSS x nonbiodegradable (ssO.it VSS for municipal waste)



    SS.. = inert inorganic SS fraction in the influent



    (5)  Substitute  Fe  for winter and summer conditions into equation

below and check against allowable winter and summer BOD,_ effluent.  In

this equation  M (eff) = M   in lagoon.
                8>
                        (BOD \    = F  +





    (6)  Determine oxygen uptake rate.
                   dt



and calculate oxygen for peak load
                    0. 5(F. - F  )    Q
               0  _ J - i - g_ x — -E- + 1.U2K M  (O.T6)
                2        t         Q           e a
                                    avg
where


    dO/dt = oxygen uptake rate, mg/A/hr



       F. = influent BOD  , mg/£



       F  = effluent BODr, mg/£
        e               ?


        t = detention time, days
       M  = total mass, mg/£
        a
                                  7-209

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EM 1110-2-501
Part 1 of 3
29 Sep 78

      M  = endogenous mass, mg/£

      Q  = peak flow, mgd

    Q    = average flow, mgd

      K  = endogenous respiration rate/hr

    (7)  Design mechanical aeration system and check horsepower supply
to keep all solids in suspension; horsepower required to keep solids in
suspension _>0.06 hp/1000 gal.

    (a)  Assume the following design parameters.

    1_  Standard transfer efficiency, Ib/hp-hr (0 dissolved oxygen,.20°C,
and tap water).

    2  0  transfer in waste/00 transfer in water saO.9.
        d.                    cL

    _3_  0  saturation in waste/0  saturation in water «0.9«

    k_  Correction factor for pressure «1.0.
    (b)  Select summer operating temperature (25-30°C) and determine
    m standard tables) 0Q saturation.

    (c)  Adjust standard transfer efficiency to operating conditions.
                          [(C.) (
                OTE = STE	x      	- a(l.02)T~2°
where
      OTE = operating transfer efficiency, Ib 0 /hp-hr

      STE = standard transfer efficiency, Ib 0 /hp-hr

        J  = 0  saturation at the selected summer temperature T, °C,
        T   in mg/£

        3=0  saturation in waste/0  saturation in water «0.9
                                 7-210

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                                                           EM 1110-2-501
                                                             Part 1 cf 3
                                                              29 Sep 78

        p = correction factor for pressure si.O

       C  = minimum dissolved oxygen to be maintained in the "basin
            > 2.0 mg/£

        a = 0  transfer in waste/0  transfer in water «0.9

        T = temperature, °C

    (d)  Calculate horsepower requirement.


                     hp - - -     - - -x 1000
where

     hp = horsepower required/lOQjp gal

     0  = oxygen required, Ib/day

    OTE = operating transfer efficiency, Ib 02/hp-hr

      V = volume cf basin, gal

    (8)  Determine nutrient requirements.


                    BOD: Nitrogen: Phosphorus = 100:5:1

    b.  Eckenf elder ' s Approach.

    (1)  Determine size of lagoon.

    (a)  Select the BOD removal rate constant, the endogenous respira
tion rate, the fraction of BOD synthesized, and temperature (summer,
winter)  S

    (b)  Adjust the BOD removal rate constant for winter and summer.
                                     (T-20)
                            KT = K208

where

     K  = BOD removal rate constant, 1/mg/hr

                                7-211

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78

    K   = rate constant at 20°C

      6 = temperature correction coefficient

      T = temperature, °C

    (c)  Solve following equation for  t  to satisfy winter conditions
and desired treatment.
                            "k = 	±	
                                24aKS  - b
                                     e
where

     t = detention, days

     a = fraction of BOD synthesized

     K = BOD removal rate constant, £/mg/hr

    Sg = effluent soluble BOD   mg/£

     b = endogenous respiration rate, I/day

    (d)  Solve equation above for  t  to satisfy summer conditions and
desired treatment.

    (e)  Select larger  t  calculated above.

    (f)  Calculate volume of pond.

                                 V = Qt
where

    V = volume of pond, million gal

    Q = flow, mgd

    t = detention time, days

    (2)  Determine MLVSS; substitute value of  t  (determined above) into

                                  X  + aS
                                   1 + bt

                                 7-212

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29  Sep  78"
where
    X. = MLVSS, mg/£
    X  = suspended solids in influent, mg/£

     a = fraction of BOD synthesized

    S  = BOD removed, mg/£

     b = endogenous respiration rate, 1/mg/hr

     t = detention time, days

    (3)  Calculate oxygen requirements.


               02 = (a')(Sr)(Q)(8.3U) + (b

where

    Op = oxygen required, Ib/day

    a' = fraction of BOD oxidized for energy

    S  = BOD removed, mg/£

     Q = flow, mgd

    b' = endogenous respiration rate, 1/hr

    Xy = MLVSS, mg/£

     V = volume of the pond, million gal

    (k)  Design mechanical aeration system and check horsepower supply
to keep all solids in suspension:  horsepower required to keep all
solids in suspension >_0.06 hp/1000 gal.

    (a)  Assume the following design parameters.

    !_  Standard transfer efficiency, Ib/hp-hr (0  dissolved oxygen,
20°C, and tap water).

    2_  0  transfer in waste/0  transfer in water  wO.9-

                                 7-213

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EM 1110-2-501
Part 1 of 3
29 Sep 78

    3.  0  saturation in waste/0  saturation in water «s0.9.

    U_  Correction factor for pressure ssl.O.
     (b)  Select slimmer operating temperature  (25-30°C) and  determine
     n standard tables) 0  saturation.
     (c)  Adjust standard transfer efficiency  to operating conditions.

                                           ]
                       - CL
OTE - STE	"     	± a(l.02)T~2°
where
      OTFJ = operating transfer efficiency, Ib 0 /hp-hr

      STE = standard transfer efficiency, Ib 0 /hp-hr

     (C )  =0.2 saturation at selected summer temperature T,  °G, mg/&
        j
        6 - 00 saturation in waste/0  saturation in water s=0.9

        p "- -jc/yeoticri factor for pressure «1.0

       C  = minimum dissolved oxygen to be maintained in the  basin
            > 2.0 mg/£

        a, = 0,.  transfer in waste/00 transfer in water «O.O
             ^'                    ^

        T = temperature, °C

     (d)  Calculate horsepower requirement.


                    hp = - — -    - x 1000
where

     hp = horsepower required/1000 gal
     0  = oxygen required, it/day
                                7-21U

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                29 Sep  78

    OTE =• operating transfer efficiency, Ib 0 /hp-hr

      V = volume of the pond, gal

    (e)  Calculate nutrient requirements.


                    BOD:Nitrogen:Phosphorus = 100:5:1

    (f)  Determine effluent BOD.


                           BODeff - Se +

where

    BODeff = effluent BOD,  mg/£

        Sg = effluent soluble BOD , mg/£

        Xy = MLVSS,  mg/H

T-71.   Output Data.

    a.   Lagoon.

    (l)  Summer  temperature,  °C.

    (2)  Winter  temperature,  °C.

    (3)  Effluent  BOD,  mg/£.

    (4)  Fraction  BOD synthesized.

    (5)  Fraction  BOD oxidized.

    (6)  Endogenous  rate  (b,  b1).

    (7)  Temperature coefficient.

    (8)  Detention time,  days.

    (9)  MLVSS, mg/£.
                                7-215

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EM 1110-2-501
Part 1 of 3
29 Sep 78

    (10)  Volume, million gal.

    (11)  Oxygen requirement, Ib/day.

    (12)  Nitrogen requirement, Ib/day.

    (13)  Phosphorus requirement,  Ib/day.

    (iH)  Total effluent BOD, mg/£..

    b.  Mechanical Aeration System.

    (l)  Standard transfer efficiency, Ib 0_/hp-hr.

    (2)  Operating transfer efficiency, Ib 0 /hp-hr.

    (3)  Horsepower required/1000 gal.

7-72.   Example Calculations (Eckenfelder's Approach).

    a.  Determine size of lagoon.

    (l)  Select design parameters.

    (a)  k = 0.001

    (b)  a = 0.73

    (c)  b = 0.075/day

    (d)  T = 25°C summer, 15°C winter

    (2)  Adjust  K  for winter and summer conditions.


                                      T-20
                              T    20

where

     K  = removal rate constant at T, £/mg/hr

    KgQ = removal rate constant at 20°C, 0.001 &/mg/hr

      6 = temperature correction coefficient, 1.035

                                 7-216

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                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                              29 Sep  78



      T = temperature,  15°C winter,  25°C summer.




                         K15 = 0.001(1.035)15~2°




                       K   = 0.00084 £/mg/hr winter





                         K25 = 0.001(1.035)25"2°




                       K   = 0.00119 £/mg/hr summer




    (3)  Under winter conditions determine detention time for desired

treatment.




                             t = 24aKS  ^b
                                      e

where



     t = detention time, days



     a = 0.73



     K = K^  = 0.00084



    S  = effluent BODC = 15 mg/£
     e               :>


     b = 0.075/day
                    t =
                        24(0.73)0.00084(15) - 0.075



                         t = 6.9 days, say 7 days
     (4)  Solve for summer conditions.



                                     1
                    t =
                        24(0.73)(0.00119)15 - 0.075



                         t = 4.2 days, say 4 days
     (5)  Select larger  t  .  t = 7-0 days




                                 7-217

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EM 1110-2-501
Part 1 of 3
29 Sep 78

    (6)  Calculate volume of the pond.

                                  V = Qt

where

    V = volume, million gal

    Q = flow, 1.0 mgd

    t = detention time, 7 days

                                V = 1.0(7)

                             V = 7 million gal

    b.  Determine MLVSS.
                                   X  + aS
                               T    1 + bt

where
    X  = MLVSS, mg/£
    X  = influent suspended solids, 200 mg/£

     a = 0.73

    S  = S  - S  = 200 - 15 = 185 mg/£
     roe
     b = 0.075/day

     t = 7 days

                              = 200 + 0.73(185)
                           \    1 + 0.075(7)
                             Xy = 220 mg/£
     c.   Calculate oxygen requirements.


                                 7-218

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep  78
                      = (a')Sr(Q)8.3U
where
    0  = oxygen required, lb/day
    a' = 0.52

    S  = 185

     Q = average flow, 1.0 mgd

    To' = 0.15/day

    X  = MLVSS, 220 mg/£

     V = volume of basin, 7 million gal


                02 = 0.52(185)1.0(8.3*0 + 0.15(220)7(8.

                             02 = 2729 lb/day

    d.  Design mechanical aeration system and check horsepower supply to
keep all solids in suspension:  horsepower >0.06 hp/1000 gal.

    (l)  Assume the following parameters.

    (a)  STE = 5 percent

    (b)  a = 0.9

    (c)  3 = 0.9

    (d)  p = 1.0

    (2)  Select summer operating temperature and determine 0  saturation.
Temperature = 25°C.  (cs)2£r = 8-2 mg/£.

    (3)  Adjust the standard transfer efficiency to operating conditions.
                                          ]
                3p - CL
OTE = STE	±—;	 a(l.02)T~2°
                                  7-219

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EM 1110-2-501
Part 1 of 3
 29 Sep 78

where

      OTE = operating transfer efficiency, percent

      STE = standard transfer efficiency, 5 percent

    (C )  =8.2 mg/£
    V s/T

        e = 0.9

        P = i.o

       C  = minimum dissolved oxygen, 1.0 mg/&
        J_i

     9.17 = 0^ saturation at 20°C
             c.

        a = 0.9

        T = 25°C

                OTE = 5 [8.2(0.9)1.0-1.03 0.9(1.02)25-20
                               y • -L i

                            OTE =3.5 percent

    (it)  Calculate horsepower requirement.
                                    °2    1000
                               ~ OTE(24)V  1Q6

where

     hp = horsepower required per 1000 gal

     0  = oxygen required, 2729 Ib/day

    OTE = operating transfer efficiency, 3-5 percent

      V = volume of "basin, 7 million gal
                             hp =  2729(1000)
                                 7-220

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78

    hp = 0.005 hp/1000 gal < 0.06 required to keep solids in suspension.
Therefore use hp = 0.06 hp/1000 gal.
                   Total hp = 0.06>         - U20hp
    (5) Calculate nutrient requirements.

       BOD.-W.-P = 100:5:1

           BOD =200 mg/£

    N required = 10 mg/£

    P required = 2 mg/£

    (6)  Determine effluent BOD.
                            BOD _ = S.  + 0.3Xy
                               eff    e

where
    BOD „„ = effluent BOD, mg/£
       eri
        S  = effluent soluble BOD, 15
        X  = MLVSS, 220 mg/£
                          BODeff = 15 + 0.3(220)

                             BODeff = 8l/mg/A

T-T3.  Cost Data.  Appropriate cost data and economic evaluation may
be found in Chapter 8.

7-7^.  Bibliography.

    a.  Barnhart, E. L. and Eckenfelder, W. W.,  Jr., "Theoretical Aspects
of Aerated Lagoon Design," Symposium on Wastewater Treatment for Small
Municipalities, 1965» Ecole Polytechnique, Montreal, Quebec, Canada.
                                7-221

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EM 1110-2-501
Part 1 of 3
29 Sep 78

    b.  Bishop, N. E., Malina, J. F., Jr., and Eckenfelder, W. W., Jr.,
"Studies on Mixing And Heat Exchange in Aerated Lagoons," Technical Re-
port EHE-70-21, CRWR-70, 1970, Center for Research in Water Resources,
University of Texas at Austin.

    c.  City of Austin, Texas, "Design Guides for Biological Wastewater
Treatment Processes," Report No. 11010ESQ, Aug 1971, U. S. Environmental
Protection Agency, Washington, D. C.

    d.  Eckenfelder, W. W., Jr., Industrial Water Pollution Control
McGraw-Hill, New York, 1966.

    e.  Eckenfelder, W. W., Jr., "Aerated Lagoons," Manual of Treatment
Processes.   Vol I, 1969, Environmental Science Services, Inc., Briar-
cliff Manor, New York.

    f.  Eckenfelder, W. W., Jr., "General Concepts of Biological Treat-
ment," Manual of Treatment Processes, Vol 1, 1969, Environmental Science
Services, Inc., Brlarcliff Manor, New York.

    g.  Eckenfelder, W. W., Jr., Water Quality Engineering for Practicing
Engineers,  Barries and Nobel, New York, 1970.

    h.  Eckenfelder, W. W., Jr., and Ford, D. L., Water Pollution
Control,  Pemberton Press, New York, 1970.

    1.  McKinney, R. E., Microbiology for Sanitary Engineers, McGraw-
Hill, New York, 1962.

    j.  McKinney, R. E., "Design and Operation of Complete Mixing
Activated Sludge Systems," Environmental Pollution Control Services
Reports,  Vol 1, No. 3,  Jul 1970, pp 1-3^.

    k.  McKinney, R. E. and Benjes, H. H., "Design and Operation of
Aerated Lagoons," Paper No. 3P2-1, Jul 1965, National Symposium on
Sanitary Engineering Research, Development and Design.

    1.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection,
Treatment,  and Disposal, McGraw-Hill, New York, 1972.

    m.  Sawyer, C. N., "New Concepts in Aerated Lagoon Design and
Operation," Advances in Water Quality Improvements - Physical and
Chemical Processes,  E. F. Gloyna and W. W. Eckenfelder, Jr., ed. ,
University of Texas Press, Austin, 1970.


                                 7-222

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78

               Section XI.   AERATED FACULTATIVE LAGOONS

7-75'  Background.

    a.  The contents of this type of lagoon are not  completely mixed.
Thus, portions of the incoming solids and the biologically produced
solids settle out and undergo anaerobic decomposition.   As a result,  '
the facultative lagoon produces a higher quality effluent than does the
aerobic one.

    b.  This type of lagoon may be useful in warm and arid climates, par-
ticularly in those areas requiring total retention,  i.e. a facultative-
evaporative lagoon.

7-76.  Input Data.

    a.  Wastewater flov.

    (l)  Average daily, mgd.

    (2)  Peak (hourly), mgd.

    b.  Wastewater characteristics.

    (1)  BOD influent, mg/£.

    (2)  Suspended solids,  mg/£.

    (3)  Volatile suspended solids (VSS), mg/£

    (k)  Nitrogen,  mg/£.

    (5)  Phosphorus, mg/£.

    (6)  Nonbiodegradable fraction of VSS.

    c.  Desired degree of treatment.

    d.  Temperature, °F or °C (summer and winter).

7-77-  Design Parameters.

    a.  Reaction rate constant/day (0.5-1-0, avg 0.75).

    b.  Temperature correction coefficient «1.075.

                                 7-223

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Part 1 of 3
 29 Sep 78

    c.  Fraction BOD removed for respiration (0.9-1.4).

    d.  BOD feedback from bottom or sediment (summer = 20 percent;
winter = 5 percent).

    e.  MLVSS, mg/£ (50-150) average 100.

7-78-  Design Procedure.

    a.  Select the rate constant,  K .   Adjust  K  for summer and winter
temperatures.


                            K  = K  0(T~2°)

where

     K^ = rate constant for desired temperature, °C

    K   = rate constant at 20°C

      6 = temperature correction coefficient

      T = temperature, °C

    b.  For summer and winter efficiencies, calculate detention times to
meet winter efficiency.

                           Se
                           S^= 1 + Kt  (1<05)

where

    S  = effluent soluble BOD,-, mg/£
     e                       5
    S  = influent BOD , mg/£

     K = reaction rate constant

     t = detention time, days

and summer efficiency

                           S
                            e     1
                           S    1 + Kt


                                 7-22^

-------
Select the larger of the detention times.

    c.  Calculate volume.


                               V = Q   t
                                    avg

where

       V = volume, million gal

    Q    = average daily flow, mgd
     avg

       t = detention time, days

    d.  Determine oxygen requirements.   Assume  a'
                             = a'SrQ(8.
where
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
    0  = oxygen required, Ib/day

    a1 = fraction of BOD oxidized for energy

    S  = BOD removed, mg/£

     Q = flow, mgd

    e.  Determine amount of effluent solids (50-150) mg/£.

    f.  Design mechanical aeration system and check horsepower supply
to allow solids to settle:  horsepower required to allow solids to
settle (0.01-0.02 hp/1000 gal).

    (l)  Assume the following design parameters.

    (a)  Standard transfer efficiency, Ib/hp-hr (0 dissolved oxygen,
20°C, and tap water).

    (~b)  02 transfer in waste/02 transfer in water asO.9.

    (c)  0  saturation in waste/0  saturation in water «£).9-

                                 7-225

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EM 1110-2-501
Part 1 of 3
 29 Sep 78

    (d)  Correction factor for pressure
    (2)  Select summer operating temperature (25-30°C) and determine
    m standard tables) 0  saturation.

    (3)  Adjust standard transfer efficiency to operating conditions.
                                          I          T1—90
              OTE = STE -	——	 (a) (1.02)
where
      OTE = operating transfer efficiency, Ib 0 /hp-hr

      STE = standard transfer efficiency, l"b 0 /hp-hr

    (c \  = Q  saturation at selected summer temperature, mg/£
    ^ S' m    <-
        3=0  saturation in waste/0  saturation in water aaO.9

        p = correction factor for pressure ssiL.O

       C  = minimum dissolved oxygen to be maintained in the basin
            > 2.0 mg/£

        a = 0  transfer in waste/0  transfer in water ;*0.9

        T = temperature, °C

    (k}  Calculate horsepower requirement.
                                               1000
                          i OTE


where

     hp = horsepower required/1000 gal

     ®2 = oxygen required, Ib/day

    OTE = operating transfer efficiency, Ib 0 /hp-hr

                                 7-226

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
      V = volume of the basin, gal

     .   Calculate BOD in effluent.
                      (BOD)eff = Se + 0.3(VSS)eff
where
    (BOD)    = BOD in effluent, mg/£

          S  = effluent soluble BOD ,  mg/£

    (VSS)    = effluent volatile suspended solids,  mg/£

    h.  Determine nutrient requirements.

                    BOD: Nitrogen-.Phosphorus = 100:5:1

7-79.   Output Data.

    a.  Lagoon.

    (l)  Summer temperature,  °C.

    (2)  Winter temperature,  °C.

    (3)  Effluent BOD, mg/£.

    (U)  Reaction rate constant, I/day.

    (5)  Temperature correction coefficient.

    (6)  Detention time, days.

    (7)  MLVSS,  mg/£

    (8)  Volume, million gal.

    (9)  Oxygen requirement,  Ib/day.

    (10)  Nitrogen requirement, Ib/day.

    (11)  Phosphorus requirement,  Ib/day.


                                 7-227

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EM 1110-2-501
Part 1 of 3
 29 Sep 78

    (12)  Total effluent BOD, Ib/day.

    b.  Mechanical Aeration System.

    (l)  Standard transfer efficiency, Ib 0 /hp-hr.

    (2)  Operating transfer efficiency, Ib 0 /hp-hr.

    (3)  Horsepower required, hp.

7-80.   Example Calculations.

    a.  Select reaction rate constant  K  and adjust for temperature
(25°C).

                                      (T-20)
                            K25 ' K206
where
    K   = reaction rate at 25°C, rate/day

    K   = reaction rate at 20°C, 0.75/day

      6 = temperature correction coefficient, 1.075

      T = temperature, 25°C


                         K   = 0.75(1.075)25~2°
                             K2Q = 1.077/day
    b.  Calculate detention times for winter and summer efficiencies,

    For winter

                           S
                           S    1 + Kt
                            o
                                  1    (1-05)
where
      S  = effluent soluble BOD   15 mg/£
                                 7-228

-------
      S  =  influent  BODC,  200 mg/£
       o               5

       K =  reaction  rate  constant,  1.077/day


       t =  detention time, days


    1.05 =  BOD feedback from sediment  in winter
                        15 _
                       200   1 + 1.077(t)


                               t - 12 days



    For summer
                          S
                                          (1.05)
                          —
                          S  ~ 1 + K(t)    '
                           o


where


    1.2 = BOD feedback from sediment in summer
                                           (1.2)
                        200   1 + l.OTT(t)



                          t = lU-9 avg 15 days



    Select larger detention time,  t = 15 days


    c.  Calculate volume of lagoon.



                                V = Q   t
                                     avg


where


       V = volume of lagoon, million gal



    Q    = average daily flow, 1.0 mgd
     avg


       t = detention time, 15 days




                                 7-229
                                                          EM  1110-2-501

                                                            Part  1  of  3

                                                              29  Sep 78

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EM 1110-2-501
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29 Sep 78

                               v = 1.0(15)

                           V = 15 million gal

    d.  Determine oxygen requirements.


                           02 = a'SrQ(8.3H)l.2

where

     Op = oxygen required, Ib/day

     a' = 1,1

     Sr = SQ - Se = 185 mg/£

      Q = flow, 1.0 mgd

    1.2 = Ib 0  required per Ib BOD removed


                        o2 = 1.1(185)1.0(8.3^)1.2


                            0  = 203T Ib/day
    e.  Determine effluent solids.

Assume  (SS)eff = 100 mg/Jl.

    f.  Design mechanical aeration  system.

    (l)  Assume the following parameters.

    (a)  STE =5.0 percent

    (b)  a = 0.9

    (c)  g = 0.9

    (d)  p = 1.0

    (2)  Select summer temperature  (25°C)  and determine 0  saturation.
(Cs)25 = 8.2 mg/£ .                                       2


                                 7-230

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                                                           EM  1110-2-501
                                                             Part  1  of  3
                                                               29 Sep 78
    (3)  Adjust STE to operating conditions.
                                   61 TV   P
                                   II> ~ ^T
                                          I      T_?n
                OTE = STE	"     	- al.02
}
where

      OTE = operating transfer efficiency, percent

      STE = standard transfer efficiency, 5-0 percent

     (C )  =8.2 mg/H
     ^   rp
        3 = 0.9

        p = 1.0

       CT = minimum dissolved oxygen, 0 mg/£
        LJ

        a = 0.9

     9.17 = 0  saturation at 20°C

        T = 25°C

               OTE = 5.0 E8.2(0.9)l..O - 0] 0.9(1.02)25-20
                               y • -L i        *

                               OTE = k.Q%
    (k)  Calculate horsepower required

                                00(1000)
                           hp
                              OTE 2it(V)(lO
where

     hp = horsepower required, hp/1000 gal

     Og = oxygen required, 2037 Ib/day



                                  7-231

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 EM 1110-2-501
 Part  1  of  3
 29 Sep 78


    OTE =  operating transfer  efficiency,  k.O percent

      V =  volume of basin, 15 million gal


                          hp  =   2037(1000)
                               1|.0(2M15(106)

                         hp = O.QCXU hp/1000 gal

    g.  Calculate BOD in effluent.



                        (BOD)eff = Se + °'3(VSS)eff

where


    (BOD)eff = BOD in effluent, mg/£


          Sg = soluble BOD in effluent, 15 mg/£

             = -volatile suspended solids in effluent

             = 0.8(SS)eff = 0.8(100) = 80 mg/£
                          (BOD)eff = 15 + 0.3(80)
                          (BOD)eff = 39 mg/Jl


    h.  Determine nutrient requirements.
                            BOD:N:P = 100:5:1

                             BOD =200 mg/£

                          N = 10 mg/£ required

                           P = 2 mg/Jl required

    7-81.  Cost Data.   Appropriate cost data and economic evaluation
may be found in Chapter 8.


                                7-232

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                                                           EM 1110-2-501
                                                             Part 1 of 3

                                                              29 Sep  78
T-82.   Bibliography.

    a.  Barnhart, E.  L. and Eckenfelder,  W.  W.,  Jr., "Theoretical
Aspects of Aerated Lagoon Design," Symposium on  Wastevater Treatment
for Small Municipalities, 1965, Ecole Polytechnique, Montreal, Quebec,
Canada.

    "b.  Bishop, N. E. ,  Malina, J. F., Jr., and Eckenf elder, W. W. ,  Jr.,
"Studies on Mixing and Heat Exchange in Aerated  Lagoons," Technical Re-
port EHE-70-21, CRWR-70, 1970, Center for Research in Water Resources,
University of Texas at Austin.

    c.  City of Austin, Texas, "Design Guides for Biological Waste-water
Treatment Processes," Report No. 11010ESQ, Aug 1971, U. S. Environmental
Protection Agency, Washington, D. C.

    d.  Eckenfelder,  W. W., Jr., Industrial Water Pollution Control,
McGraw-Hill, New York,  1966.

    e.  Eckenfelder,  W. W., Jr., "Aerated Lagoons," Manual of Treatment
Processes, Vol I, 1969» Environmental Science Services, Inc., Briarcliff
Manor, New York.

    f.  Eckenfelder,  W. W. , Jr., "General Concepts of Biological Treat-
ment," Manual of Treatment Processes, Vol 1, 19&9, Environmental Science
Services, Inc., Briarcliff Manor, New York.

    g.  Eckenfelder,  W. W., Jr., and Ford, D. L., Water Pollution Control,
Pemberton Press, New York, 1970.

    h.  Goodman, B. L., Design Handbook of Wastewater Systems:  Domestic,
Industrial, Commercial, Technomic, Westport, Conn., 1971-

    i.  McKinney, R.  E., "Design and Operation of Complete Mixing
Activated Sludge Systems," Environmental Pollution Control Services
Reports, Vol 1, No. 3, Jul 1970, pp 1-3^.

    j.  McKinney, R.  E. and Benjes, H. H., "Design and Operation of
Aerated Lagoons," Paper No. 3P2-1, Jul 1965, National Symposium on
Sanitary Engineering Research, Development and Design.

    k.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection,
Treatment, and Disposal, McGraw-Hill, New York,  1972.
                                 7-233

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EM 1110-2-501
Part 1 of 3
 29  Sep  78

    1.  Sawyer, C.  W., "Mew Concepts in Aerated Lagoon Design and. Opera-
tion," Advances in Water Quality Improvements - Physical and Chemical
Processes,  E. F. Gloyna and W.  W.  Eckenfelder, Jr., ed., University of
Texas Press, Austin, 1970.
                                 T-23H

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
                      Section XII.  OXIDATION DITCH
7-83.  Background.  The oxidation ditch, developed in the Netherlands,
is a variation of the extended aeration process that has "been used in
small towns, isolated communities, and institutions in Europe and the
United States.  The typical oxidation ditch (Fig. 7-9) is equipped with
aeration rotors or brushes that provide aeration and circulation.  The
sewage moves through the ditch at 1 to 2 fps.  The ditch may be designed
for continuous or intermittent operation.  Because of this feature, this
process may be adaptable to the fluctuations in flows and loadings
associated with recreation area wastewater production.
                                                      O—:
                             •ROTOR
            BAR
           SCREEN
                         OXIDATION DITCH
 FINAL
SETTLING
 TANK
                  Figure 7-9-  Typical oxidation ditch.

7-84.  Input Data.

    a.  Wastewater Flow (Average and Peak).  In case of high variability,
a statistical distribution should be provided.

    b.  Wastewater Strength.

    (1)  BOD  (soluble and total), mg/£.

    (2)  COD and/or TOG (maximum and minimum), mg/£.

    (3)  Suspended solids, mg/£.

    (M  Volatile suspended  solids (VSS), mg/fc.

    (5)  Nonbiodegradable fraction of VSS, mg/£.

    c.  Other Characterization.
                                 7-235

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EM 1110-2-501
Part 1 of 3

 29 Sep 78

    (1)  PH..

    (2)  Acidity and/or alkalinity, mg/Jl.

    (3)  Nitrogen,  mg/£.
         Phosphorus (total and soluble), rng/A.

    (5)  Oils and greases, mg/£.

    (6)  Heavy metals, mg/&.

    (7)  Toxic or special characteristics (e.g., phenols), mg/£.

    (8)  Temperature, °F or °C.

    d.   Effluent Quality Requirements.

    (1)  BOD5, nig/ A.

    (2)  SS, mg/Jl.

    (3)  TKN, ing/ A.

    (It)  P, mg/Jl.

7-85-   Design Parameters.

    a.   Reaction rate constants and coefficients.

                Eckenf elder

                    k               0.0007-0.002 A/mg/hr

                    a               0.73

                    a'              0.52

                    b               0.075/day
   The form of nitrogen should be specified as to its biological
  availability (e.g., NH  or Kjeldahl).

                                 7-236

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                                                          EM 1110-2-501
                                                             Part  1  of  3
                                                               29  Sep  78
                    bf               0.15/day

                    a               O.TTa =  0.56

                    f               O.UO

                    f               0.53

    b.   F/M = 0.03-0.1.

    c.   Volumetric loading = 10-HO.

    d.   t = 18-36 hr.

    e.   t  = 20-30 days.
         s
    f.   MLSS = ^000-8000  mg/A;  mean, 6000 mg/£.

    g.   MLVSS = 2800-5600 mg/X..

    h.   Qr/Q = 0.5-1.0.

    i.   Ib 02/Xb BODr >. 1.5-

    j.   Ib solids/lb BOD   <_ 0.2.

    k.   6 = 1.0-1.03.

    1.   Efficiency = >90  percent.

7-86.  Design Procedure.

    a.   Assume the following design parameters vhen known.

    (l)  Fraction of BOD  synthesized (a).

    (2)  Fraction of BOD  oxidized for energy (a1)-

    (3)  Endogenous respiration rate (b and b').

    (h)  Fraction of BOD   synthesized to degradable solids  (a ).

    (5)  Nonbiodegradable fraction of VSS in influent (f).
                                7-237

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EM 1110-2-501
Part 1 of 3
 29 Sep 78

     (6)  Mixed liquor suspended solids (MLSS).

     (7)  Volatile solids in mixed liquor suspended solids (MLVSS)

     (8)  Temperature correction coefficient (0).

     (9)  Degradable fraction of the MLVSS (f).

    (10)  Food-to-microorganism ratio (F/M).

    (11)  Effluent soluble BOD  (S ).

    b.   Adjust the BOD removal rate constant for  temperature.

                            K       fl(T-20)
                             T    20
where

     K_ = rate constant for desired temperature

    K   = rate constant at 20°C

      6 = temperature correction coefficient

      T = temperature, °C

    c.   Determine the size of the aeration tank.

                              a (S  - S )Q
                               O  O    f*
                          TT _  *-*  W    *~
                                (xv)(f)(b)
where

       V = aeration tank volume, million gal

      a  = fraction of BOD  synthesized to degradable solids

      S  = influent BOD , mg/£
       o               2
      S  = effluent soluble BOD , mg/£
         = waste flow, mgd
                                T-238

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                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                               29 Sep 78
      X^ = MLVSS,



      f' = degradable fraction of the MLVSS



       b = endogenous respiration rate, I/day



    d.  Calculate the detention time.








where



    t = detention time, hr



    V = volume, million gal



    Q = flow, mgd



    e.  Assume the organic loading and calculate detention time.



                                    2l|S
                                t _ 	o



                                    •^V M


where



      t = detention time, days



     S  = influent BOD.., mg/£
      o               ?


     X  = volatile solids in raw sludge, mg/fc



    F/M = organic loading (food-to-microorganism ratio)



and select the larger of two detention times from d. or e.



    f.  Determine the oxygen requirements allowing 60 percent for

nitrification during summer.
       °2 = a'SQ(8-3M + fc'XtS.aU) + °'6^-57) (
                                7-239

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EM 1110-2-501
Part 1 of 3

29 Sep 78

where
      0  = oxygen required, Ib/day
      a1 = fraction of BOD oxidized for energy

      Sr = BOD  removed, mg/£

    Q    = average waste flow, mgd

      b' = endogenous respiration rate, I/day

      Xy = MLVSS, mg/H

       V = aeration tank volume, million gal

     TKN = total Kjeldahl nitrogen, mg/£

and calculate oxygen requirement (>1.5).
                        Ib BODr   (Q)(Sr)(8.3U)
where
    0  = oxygen required, Ib/day

     Q = waste flow, mgd

    S  = BOD  removed, mg/£

    g.   Calculate sludge production.


  AXy = 8.3^[a(Sr)(Q) - (b)(Xy)(V) - Q(SS)eff + Q(VSS)f + Q(SS - VSS)]
  t

where

    AX^. = volatile sludge produced, Ib/day

      a = fraction of BOD synthesized
        = BOD  removed, mg/£
                                 T-2UO

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                                                           EM  1110-2-501

                                                            Part  1  of  3

                                                               29 Sep 78
           Q, = waste flow,  mgd



           to = endogenous respiration  rate,  I/day



          X  = volatile solids in raw  sludge,



           V = aeration tank volume, million gal



     (SS)  „ = effluent suspended solids,  mg/fc



         VSS = volatile suspended solids  in  influent,  mg/£



          f' = degradatole fraction of  the  MLVSS



    (VSS) „_ = effluent volatile suspended solids,  mg/£
         efi


    h.   Calculate solids produced per  pound  of BOD  removed.
                       Ib solids        AXV
                        Ib BOD     Q(S  -  S )8.
where



    AX  = volatile sludge produced,  Ib/day



      Q = waste flow, mgd



     S  = influent BOD ,  mg/£
      o               p


     S  = effluent soluble BOD^, mg/£
      e                       5


    i.  Calculate the solids retention time.



                                 X (V)(8.3U)

                            t  =  a
                                     AXv

where



     t  = solids retention time, days
      S


     X  = MLSS, mg/£
      3,


      V = volume of aeration tank, million gal

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EM 1110-2-501

Part 1 of 3


29 Sep 78


    AX^ = volatile sludge produced, Ib/day



    j.   Determine the effluent soluble BOD ,
                             S
                              e _ 	

                             S  ~ 1
                              o

where
    S  = soluble effluent BOD, mg/£
     G


    S  = influent BOD, mg/£



     k = rate constant, 1/mg/hr



    X^ = MLVSS, mg/£



     t = aeration time, hr



    k.  Calculate sludge recycle ratio.
                             Q      X  - X
                              avg    u    a



where



      Q  = volume of recycled sludge, mgd



    Q    = average flow, mgd
      X  = MLSS, mg/£
       cl


      X  = suspended solids concentration in returned sludge,  mg/£



    1.   Calculate the nutrient requirements  for nitrogen
                              N = 0.123AXy



and phosphorus



                              P = 0.026AXV





                                 T-2U2

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                                                           EM 1110-2-501
                                                             Part  1 of 3
                                                              29 Sep 78
where
    AX  = sludge produced, Ib/day

7-87.   Output Data.

    a.  Aeration Tank.

     (l)  Reaction rate constant, 1/mg/hr.

     (2)  Sludge produced per BOD removed.

     (3)  Endogenous respiration rate (b, ~b').

     (k)  0  utilized per BOD removed.

     (5)  Influent nonbiodegradable VSS.

     (6)  Effluent degradable VSS.

     (7)  lb BOD/lb MLSS-day (F/M).

     (8)  Mixed liquor  suspended solids, mg/& (MLSS).

     (9)  Mixed liquor  volatile suspended solids,  mg/£ (MLVSS).

    (10)  Aeration time,  hr.

    (ll)  Volume of aeration tank,  million  gal.

    (12)  Oxygen required, Ib/day.

    (13)  Sludge produced, Ib/day.

    (Ik)  Nitrogen requirement, Ib/day.

    (15)  Phosphorus requirement, Ib/day.

    (16)  Sludge recycle  ratio, Ib/day.

    (17)  Solids retention time, days.

    b.   Mechanical Aeration System.

    (l)   Standard transfer efficiency, lb 0 /hp-hr.

                                7-21*3

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EM 1110-2-501

Part 1 of 3

 29 Sep 78



    (2)  Operating transfer efficiency, l"b 0 /hp-hr.



    (3)  Horsepower required, hp.



    c.  Diffused Aeration System.



    (l)  Standard transfer efficiency, percent.



    (2)  Operating efficiency, percent.



    (3)  Required air flow, cfm/1000 ft3.



7-88.   Example Calculations (Eckenfelder's Approach).



    a.  Assume the following design parameters.



      (1)  a - 0.73



      (2)  a' = 0.52



      (3)  b - 0.075/day, V = 0.15/day



      (U)  a  = 0.56
           o


      (5)  f = 0.1+0



      (6)  MLSS = X  = 6000 mg/H
                  Si


      (7)  MLVSS = Xy = 1*200 mg/£



      (8)  e = 1.02



      (9)  f - 0.53



    (10)  F/M = 0.06



    (11)  S  =10 mg/£



    "b.  Adjust the BOD removal rate constant for temperature.


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                                                           EM 1110-2-.501

                                                             Part 1 of 3

                                                               29 Sep 78
where



     K™ = removal rate constant at T°C



    K   = removal rate constant at 20°C, 0.0010


      0 = 1.02



      T = 1S°C



                          KT = 0. 001(1. 02)15~2°



                               K.J, = 0.0009



    c.  Determine the size of the aeration tank.



                              a (S  - S )Q
                          v -  oo    ex  avg
where



       V = volume of aeration tank, million gal


      ao = 0.56


      S  = influent BOD ,  200 mg/£



      S  = effluent soluble BOD ,  10 mg/l



    Qa   = average flow, 1.0 mgd


      Xy = MLVSS, 4200 rng/A


      f  = 0.53


       b = 0.075/day
                         V = 0-56(200 - 10)1.0

                              4200(0.53)0.075
                          V = 0.64 million gal
                               7-2^5

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EM 1110-2-501
Part 1 of 3

29 Sep 78
    d.  Calculate detention time.
where

    t = detention time, hr

    V = volume, 0.6U million gal

    Q = average flow, 1.0 mgd
                                t = 15 hr

    e.  Assume organic loading and calculate detention time.

                                  2k(S )
                              t =

where

      t = detention time, hr
     S  = influent BOD , 200 mg/£
     Xy = MLVSS, U200 mg/fc

    F/M =0.06
                              =  2U(200)
                                U200(0.06
                                t = 19 hr

Select larger detention time,  t = 19 hr

    f.  Determine oxygen requirements allowing 60 percent for nitrifica-
tion during summer.


              00 = [a'S Q    + b'XV + 0.6(4.5T)TKN(Q)]8.31+
               2       r avg      v

                                 T-2H6

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                                                           EM 1110-2-501

                                                             Part  1 of 3


                                                               29 Sep 78


where



      0  = oxygen required, Ib/day



      a1 = 0.56



      S  = S  - S  = 190 mg/£



    Q    = average flow, 1.0 mgd



      b' = 0.15/day



      Xy = MLVSS, 4200 mg/£



       V = volume of aeration tank,  0.6h million gal



    4.57 - parts oxygen required per part TKN



     TKN = total Kjeldahl nitrogen,  30 mg/£



       02 = [0.56(190)1.0 + 0.15(4200)0.64 + 0.6(4. 57)30(1.



                            O  = 4936 Ib/day
    g.  Calculate oxygen required per pound of BOD removed.
                        lb BOD    Q   (S )8.34
                              r    avg  r
where
      0  = oxygen required, 4936 Ib/day



    !J    = average flow, 1.0 mgd



      S  = BOD removed, 190 mg/£




                         lb °2        4936
                        lb BOD    190(1.0)8.34



                         lb 0

                                = 3.0 > 1.5  (OK)
                        lb BOD
                              r
                                 7-247

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EM 1110-2-501
Part 1 of 3
 29 Sep 78

    h.  Calculate sludge production.


        AXy = [aSrQ - bXyV - Q(SS)eff + Q(VSS)f + Q(SS - VSS)]8.3U

where

        A3C. = sludge produced, Ib/day

          a = 0.73

         S  = BOD removed, S  - S  = 190 mg/£

          Q = average flow , 1.0 mgd

          b = 0.075/day

         Xy = MLVSS 1*200 mg/A

          V = volume of aeration tank, 0.6k million gal

    (SS)eff = solids in effluent, 20 mg/£

        VSS = volatile solids in, influent, 150 mg/Jl

         f = 0.53

         SS = solids in influent, 200 mg/£


            AXy = [0.73(190)1.0 - 0.075(^200)0.61+

                  - 1.0(20) + 1.0(150)0.53 + 1.0(200 - 150)]8.3U


                            A   = 389 Ib/day
    i.  Calculate solids produced per pound of BOD removed.


                       113 solids _      Axy
where
    AXy = sludge produced, 389 Ib/day

                                7-248

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                                                            EM 1110-2-501

                                                              Part 1 of 3

                                                                29 Sep 78
        = average flow,  1.0 mgd
     S  = influent BOD,  200 mg/£
      o


     S  = effluent BOD,  10 mg/£
                     Ib solids _ 	389	

                      It BOD   ~ 1.0(200 - 10)8.31*
                                              (OK)
    j.  Calculate solids retention time.



                                   X V8.31*
where



     t  = solids retention time, days
      o


     X  = MLSS, 6000 mg/SL
      El


      V = volume of aeration tank, 0.61* million gal



    AX^ = solids produced, 389 Ib/day





                             _ 6000(0.6l*)8.31*

                           s        389
                          t  = 82 days
                           S
    k.   Determine effluent soluble BOD .
                             fe

                             so
                                 7-21*9

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EM 1110-2-501

Part 1 of 3


 29 Sep 78


where



    S  = soluble effluent BOD, mg/£



    S  = influent BOD, 200 mg/£
     o


     K = reaction rate constant, 0.0009



    Xy = MLVSS, 4200 mg/£



     t = detention time, 19 hr
                       S
                        e
                       200   1 + (0.0009)^200(19)




                             S  =2.7 mg/£
    1.  Calculate sludge recycle ratio.
                              Q       X
                               r       a
                                    X  - X
                              avg    u    a
where
      Q  = recycle flow, mgd



         = average flow, 1.0 mgd
     avg


      X  = MLSS, 6000 mg/£
       a


      X  = underflow concentration, 10,000 mg/£
                          Qr  =     6,000

                          1.0   10,000 - 6,000
                                = 1.5
    m.  Calculate nutrient requirements for nitrogen.




                                7-250

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                                                           EM 1110-2-501
                                                             Part 1 of 3

                                                              29 Sep  78

                             N = O.
                             N = 0.123(389)

                             N = 1*8 Ib/day

for phosphorus

                             P = 0.026AX

                             P = 0.026(389)

                             P = 10 Ib/day

                      N in influent = 30

                                    = 30(1. 0)8. 3U

                                    =250 Ib/day > hQ Ib/day

                      H to be added = none

                      P in influent = 15 mg/&(Q)8. 3^

                                    = 15(1.0)8. 3U

                                    = 125 Ib/day > 10 Ib/day

                      P to be added = none

7-89.  Cost Data.  Appropriate cost data and economic evaluation may
be found in Chapter 8.

7-90.  Bibliography.

    a.  Guillaume, F. P., "Evaluation of the Oxidation Ditch as a Means
of Waste-water Treatment in Ontario," Research Publication Wo. 6, Jul
196U, The Ontario Wastewater Commission, Ontario, Canada.

    b.  Lakeside Engineering Corporation, "Rotor Aeration," Apr I960.

    c.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection,
Treatment, and Disposal, McGraw-Hill, New York, 1972.
                                 7-251

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EM 1110-2-501
Part 1 of 3

29 Sep 78
    d.  Nesbitt, J. B.,  "Removal of Phosphorous from Municipal Sewage
Plant Effluents," Engineering Research Bulletin B-93, 1966, College of
Engineering, Pennsylvania State University, University Park, Pa.

    e.  Prather, B. F.,  "Wastewater Aeration," The Oil and Gas Journal,
Vol 57, No. U9, 1959, pp 78-80, 8U, 86-91.

    f.  U.  S. Department of Transportation, "Oxidation Ditch Sewage
Waste Treatment Process," Water Supply and Waste Disposal Series, Vol 6,
Apr 1972, U. S. Department of Transportation, Washington, D. C.

    g.  Zeper, J. and DeMan, A., "New Developments in the Design of
Activated Sludge Tanks with Low BOD Loadings," 5th International Water
Pollution Research Conference, Jul-Aug 1971, San Francisco, Calif.

    h.  Parker, H. W., "Water Supply and Waste Disposal Series, Oxida-
tion Ditch Sewage Treatment Process," Apr 1972, U. S. Department of
Transportation, Federal Highway Administration.
                                7-252

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                                                           EM 1110-2-501
                                                             Part 1 of 1
                                                               29 Sep 78

              Section XIII.  NITRIFICATION-DENITRIFICATION

7-91.  Background.

    a.  General.  Nitrogen exerts an oxygen demand in the unoxidized
state (NH3-N) and also contributes to eutrophication of natural waters.
Hence, nitrogen is considered a pollutant and, in many cases, removal
is required.  Several methods have been developed for nitrogen removal;
perhaps the most promising biological process is the nitrification-
denitrification process.  Depending on the forms of nitrogen present in
the waste-water, biological nitrogen removal can be accomplished in one
or more stages  (fig. 7-10).  When the ammonia form is present, two
stages are required.  The initial stage involves the conversion of am-
monium to nitrates (called nitrification) by the aerobic bacteria  (nitro-
somonas and nitrobacter).  The second stage (denitrification) consists
of the anaerobic conversion of nitrate to nitrogen gas.  If the nitro-
gen is already  in the form of nitrate, as in the case of irrigation
return water, only the  second stage (or denitrification) is required.
CHEM
ADDI
LETE\
* }— *
CTOR I
SLUDGE
CAL
TION
H TANK 1 	 1
RETURN
f
HASTE
SLUDGE
ORGANIC
CARBON
ptt ADJUSTMENT »«TE
(IF REQUIRED] SLUDGE
FACILITIES FOR REDUCED
VOLUME OPERATIC*
t f
1 1
r "-"S C|-
_ /SETTLMcX
* 1 TANK J
y
SLUDGE RETURN R
INTERCONNECTED SLUDGE RETURN \ /
N CASE NITR1FICAT ON SLUDGE Y
IS WASHED OUT OR LOST 1
INTERCONNECTED FOR STARTUP,
RESEEDING AND TO AID IN OPEftAT ON
OF NITRIFICATION SYSTEM
NITRIFICATION
CHEMICAL
ADDITION
5(E 3J2
SI ||
|j3 3S FACILITIES FOR REDUCED
£§ *u- VOLUME OPERATION
11 f f ' ^


1
R SLUDGE RETURN (
WASTE
SLUDGE
DENITRIF CATION
    CONVERSION (AEROBIC'
                                                      From Metcalf and Eddy, 1972
         Figure 7-10.  Flow sheet for  a  three-stage  biological
                treatment process for  nitrogen  removal.
                                  7-253

-------
EM 1110-2-501
Part 1 of 3
29 Sep 78

    b.  Nitrification.  Nitrification can be accomplished in conventional
activated sludge reactors by increasing the solids retention time such
that it is greater than the growth rate of the nitrifier (nitrosomonas ) .
Nitrifying bacteria can exert a considerable oxygen demand;  therefore,
sufficient air must be provided to the system.  However, nitrification
is usually carried out in a separate reactor, which allows better flex-
ibility and optimum performance of both the carbonaceous oxidation and
nitrification.

    c-  Denitrification.  Denitrification results from the utilization
of chemically bound oxygen (N03) by facultative organisms in the absence
of dissolved oxygen.   Since denitrification takes place after the aero-
bic removal of carbon it may be necessary to add some carbon source in
the denitrification tank for use by the denitrifying bacteria in cell
synthesis.   A number of studies have been conducted to evaluate the
denitrification process (d, f,  g, h, and i, para 7-98).

7-92.   Input Data.

    a<  Nitrification (following first stage complete mix).

    (l)   Wastevater flow (average and peak hourly),  mgd.

    (2)   Wastevater characteristics.

    (a)   BOD , mg/£.

    (b)   NH -N (average and peak),  mg/£.

    (c)   Temperature, °C.

    (d)   pH.

    (3)   Degree of  nitrification desired,  percent.

    b.  Denitrification (following  nitrification).

    (l)   Wastewater flow (average and peak),  mgd.

    (2)   Effluent quality  from  nitrification  stage.

    (a)   N0,  N0
                                 7-25^4
                2,

    (b)   Dissolved  oxygen, mg/£.

-------
                                                           EM 1110-2-501
                                                             Part  1 of 3
                                                              29 Sep 78

    (c)   Temperature,  °C.

    (a)   PH.

    (3)   Degree of nitrification desired,  percent.

7-93.   Design Parameters.

    a.  Nitrification.

    (l)   NH  loading versus temperature and MLVSS curve (fig. 7-ll)-

    (2)   Correction factor of loading for  pH (fig.  7-12).

    (3)   MLSS, range 1500-2500 mg/SL.

    (U)   MLVSS as 0.8 MLSS.

    (5)   Percent nitrification, range 60-70 percent.

    b.  Denitrification.
                           o
    (l)   NO  lb/day/1000 ft  versus temperature and MLVSS (figs. 7-13
and 1-lk). 3

    (2)   MLSS as 1500-2500 mg/£.

    (3)   MLVSS as 0.8 MLSS.

         Methanol requirements (3-3-5 lb/lb M).
7-9^.  Design Procedure.  The design procedures for nitrification and
denitrification are based on empirical relationships developed by
Sawyer (para 7-98h).

    a.  Nitrification.

    (1)  Select a MLVSS.

    (2)  Calculate the ammonia (NH ) load, Ib/day.

                               = (Q   )(8.3U)(NH3-N)
                           avg
                                7-255

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EM 1110-2-501
Part 1 of 3
29 Sep 78
                                                    20
                                                             25
     0         5         10         15
                       TEMPERATURE , °C
Figure 7-U-  Permissible nitrification  tank loadings.
                                 7-256

-------
 100
                                                            EM 1110-2-501
                                                              Part 1 of  3

                                                               29 Sep 78
  80
  60
O
I- 40
o
cc
111
0.

  20
AT 20"C
                            I   I    I
                                               I   I    I   I
                                      8
                                      pH
        Figure 7-12.  Percent  of maximum rate of nitrification
                   at constant temperature versus pH.
                                  7-257

-------
I
IX)
Co
                              DENITRIFICATION RATE , LB   OXIDIZED  NITROGEN REMOVED/DAY/LB MLVSS


                              O           P           O           O           O            o
i . v . ..,.>•'£?
J-J. O — W C*J ^ O< 0> -J QD
(g
4
fD
-0
1
H
U)
Oi
0 M
Hj H,
Hj
PJ 0)
(DO ,
-^ i5
^ 1
H- x
Ht> rt >
H- rt> H
00 C
{D W 3J
d- tD m
H- i-J -
0 P3 o"1
» ^ 0
' n
m

£
*5
o w
x ^
3 >J] °
4 1
P ^
<^ &
^ £,
% w







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\























ss^
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-------
  ISO
                                                            EM 1110-2-501
                                                              Part 1 of 3

                                                               29 Sep 78
  160
  140
  120
D
U
  100
   80
 n
o
z
0)
   60
  40
   20
3000
                        10
                                   15
                                            20
                            TEMPERATURE ; C
                                                          MLVSS
                                                      2500
                                              2000
                                              1500
                                                      1000
                                                       25
                                                         30


                                                      From Mulbarger



Figure 7-1^-•  Permissible denitrification  tank loadings.
                                 7-259

-------
EM 1110-2-501
Part 1 of 3
 29  Sep 78


                      fm -N\  = /NH-N)
                      ^     'p   \     'avg

where

         NH-N = ammonia, mg/£

               = peak NH , Ib/day

     /        P
     (NH -NJ    = average NH , Ib/day
     \     ' avg             -*
            Q  = peak flow, mgd

          Q    = average flow, mgd
           o,Vg

    (3)  Turn to Figure 7-U; for winter temperature,  °C,  and MLVSS
selected, determine the allowable loading of ammonia,  lb/1000 ft3/day
at the optimum pH (8.4).
         Then turn to Figure 1-12; adjust loading for operating pH (see
Input Data).

    (5)  Calculate volume of tank required.
                       V   (HH )  adjusted X 100°

where
                                           o
                 V = volume of the tank,  ft

          fNH_j    = average ammonia load,  Ib/day
          *    avg
    (NH )  adjusted = allowable loading adjusted, lb/1000 ft3/day

    (6)  Determine oxygen requirements:   total oxygen = (o )  +

    (a)  For nitrification.


               (OP)  = (4.57) (%  nitrification).   v
               V 24      '*' \       100       / V  3J
                                 T-260

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
where

     10 J  = oxygen, Ib/day
         N
    /NH_\  = peak NH , Ib/day
    ^   'P
    (b)  For BOD removal.
                           = (1.5)(BODC)(Q_J(8.34)
                    v ^BOD

where

            = oxygen, Ib/day
                       BOD            ^   avg'
        BOD
       BOD  = influent BOD  to nitrification tank, mg/£

       Q    = average flow, mgd
        avg

    (T)  Design aeration systems.

    (a)  Diffused Aeration System.

    !_  Assume the following design parameters.

    a_  Standard transfer efficiency, percent, from manufacturer
(5-8 percent).

    b_  0  transfer in waste/0  transfer in water «0.9.

    c_  0  saturation in waste/0  saturation in water aO.9.

    
-------
EM 1110-2-501
Part 1 of 3
 29  Sep 78

vhere

      OTE = operating transfer efficiency, percent

      STE = standard transfer efficiency, percent

     \ s)  = ^2 saturati°n at selected summer temperature, mg/£

        3 = 02 saturation in waste/0? saturation in water «0.9

        p = correction factor for pressure si.O

       C  = minimum dissolved oxygen to be maintained in the basin
            > 2.0 mg/£

        a = 02 transfer in waste/0  transfer in water asO.9

        T = temperature, °C

    U_  Calculate required air flow.
                                0
                R  =
                'a         /        lb °o \ /       -
                     (OTE)  0.0176   ,  2  UlUtO
                           V       ft3 air/V
where
     R  = required air flow, cfm/1000 ft3
      a,

     0  = oxygen required, Ib/day

    OTE = operating transfer efficiency, percent

      V = volume of the basin, gal

    (b)  Mechanical Aeration System.

    !_  Assume the following design parameters.

    a.  Standard transfer efficiency,  Ib/hp-hr (0 dissolved oxygen,  20°C,
and tap water).

    b_  0  transfer in waste/0  transfer in water *0.9.


                                7-262

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                                                           EM 1110-2-501
                                                             Part 1 of 3

                                                              29 Sep 78
    c_  Correction factor for pressure si.O.

    d_  0  = saturation in waste/0  saturation in water asO.p-

    2_  Select summer operating temperature (25-30°C) and determine
(from standard tables) 0  saturation.

    3.  Adjust standard transfer efficiency to operating conditions.

                                (e)(p) - c
where
                OTE = STE " '  '*   17	^ a(l.02)T~20
      OTE = operating transfer efficiency, Ib 0^/hp-hr

      STE = standard transfer efficiency, Ib 0?/hp-hr

    [C )  = 00 saturation at selected summer temperature, mg/£
    \ S/T
        3 = 0  saturation in waste/0  saturation in water «0.9

        p = correction factor for pressure asL.O

       C  = minimum dissolved oxygen to be maintained in the basin
            > 2.0
        a = 0  transfer in waste/0  transfer in water saO:9

        T = temperature, °C

       Calculate horsepower reguirement.

                                 0
                    hp =	..  . x	 x 1000
where

     hp = horsepower required per 1000 gal

     Op = oxygen required, Ib/day


                                7-263

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EM 1110-2-501
Part 1 of 3

29 Sep 78
    OTE = operating transfer efficiency,  Ib 0 /hp-hr

      V = volume of the basin,  gal

    (8)  Determine sludge production.
                     0.1 lb/(lb-NH \
                            \      /removed
                   = (0.1)/NH \   (% nitrification }
                 a        V  3/avg V       100      /
where
(NH j
V   '
         A   = sludge produced,  Ib/day
          A
           a
             = average NH  loading,  Ib/day
         avg
    (9)  Determine lime requirements;  for winter conditions  add
of hydrated lime per pound of KH  removed to maintain desired pH.

    b.  Denitrif ication.

    (1)  Calculate NO  loading.
                           avg

                             = (NO )   (yQavg)
                          'p   V   /avg  ^

where
    /NO \
    \   /
         = average NO  loading,  Ib/day
     avg
    Q    = average flow,  mgd
     avg
  (NO \
  V   /
             = peak NO  loading, Ib/day
           p
      Q
             = peak flow, mgd

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                                                           EM 1110-2-501
                                                             Part  1 of 3
                                                              29 Sep 78

    (2)  Turn to Figure 7-1^;  for winter temperature and MLVSS determine
NO  loading (ib NO /1000 ft3/day) at optimum pH.

    (3)  Adjust loading for operating pH (Table 7-1)-

         Calculate volume of denitrification tank.
                         V = ——	§_	 (1000)
                             NO  loading

where
                                                        3
              V = volume of the denitrification  tank,  ft

                = peak NO  loading, Ib/day

    NO  loading = lb/1000 ft3/day

    (5)  Calculate methanol requirements.

    Methanol (ib/day) = 2.Vf(NO ) + 1.53(W02) +  0.87(Dissolved Oxygen)

Or from rule of thumb

    Methanol (ib/day) = (2.5) Ib/lb NO  reduced

                                    = (2.5)(NO \   (%  NO  reduced)
                                           V  /avg

    (6)  Determine sludge production.

                  A   =0.2 Ib/lb methanol added
                   X
                    a
or
                  A   =0.7 Ib/lb NO  reduced
                   Xa               3
where

    A   = sludge produced, Ib/day
     A
      a
                                 7-265

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EM 1110-2-501
Part 1 of 3
29 Sep  78


7-95.  Output Data.

    a.  Nitrification.

     (l)  Winter temperature, °C.

     (2)  pH.


     (3)  Effluent ammonia, mg/£.


     (it)  Mixed liquor volatile solids, mg/£ (MLVSS).

     (5)  Ammonia loading, lb/1000 ft /day.

     (6)  Volume, ft3.

     (7)  Oxygen required, lb/day.

     (8)  Sludge produced, lb/day.

     (9)  Lime required,  lb/day.

    (10)  Mechanical aeration system.

    (a)   Standard transfer efficiency,  Ib 0  /hp-hr.

    (b)   Operating transfer efficiency, Ib 0 /hp-hr.

    (c)   Horsepower required/1000 gal.

    (ll)  Diffused aeration system.

    (a)   Standard transfer efficiency,  percent.

    (b)   Operating transfer efficiency, percent.

    (c)   Required air flow, cfm/1000  ft3.

   "b-   Intermediate Clarifier.   (See chap.  5, sec IX,  Sedimentation
(Secondary  Clarifier).)

   c.   Denitrification.

    (l)   Winter  temperature,  °C.


                               7-266

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                                                          EM 1110-2-501
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                                                              29 Sep 78

    (2)  PH.

    (3)  Influent dissolved oxygen, mg/£.

    (H)  Nitrate loading, mg/£.

    (5)  Mixed liquor volatile  solids, mg/£  (MLVSS).


    (6)  Volume, ft3.

    (7)  Sludge produced, Ib/day.

    (8)  Methanol required, Ib/day.

    d.   Final Clarifier.   (See  chap.  5,  sec  IX,  Sedimentation  (Secondary
Clarifier) . )

7-96.   Example Calculations.

    a.   Nitrification.

    (1)  Select MLVSS =0.8 MLSS.


                            MLVSS = 0.8(2000)


                            MLVSS = 1600 mg/£


    (2)  Calculate NH3 load.
                     (NH -N)
                     ^  -'  '
                      (NH -N)  = (NH -N)
                      V  J  /p   V     /
          p(8.3U)(HH -N)
avg      °

                     )
            avg \ "avg /
where
               = average NH  load, Ib/day
           avg
          0    = average flow, 1.0 mgd
           avg

         NH -N = ammonia concentration, 30 mg/£


                                 T-267

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 EM 1110-2-501
 Part 1 of 3
 29 Sep 78
               = peak NH3 load, Ib/day

            Q  = peak flow, 2.0 mgd
                        (NH -N)    = 1.0(8.3^)30
                        \     ' avg

                            -N\    =250 lb/day
                              /
       3   'avg
                          /NH -N\  = 500 lb/day
                          ^     'P _

    (3)  Select winter temperature (lO°C) and MLVSS (1600 mg/£) and
determine allowable ammonia loading from Figure 7-10 at pH = 8.U.


                        NH  = 8 lb/day /1000 ft3
         Adjust NH  loading to operating pH from Figure 7-11 (pH =7.8)


                /NH \         = 87^(8 lb/day/1000 ft3)
                V   'adjusted
'adjusted


   adjusted
                   /^NlA         = 7 lb/day/1000 ft3
         Calculate volume of tank required.

                                (M3)
                                            (1000)
                                 3
                                  /adjusted
where

                                      •3
                V = volume of tank,  ft



                                7-268

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                                                          EM 1110-2-501
                                                            Part 1 of 3
                                                              29 Sep 78
    /NH \
    \  3/
          H  )    = ammonia load, 250 lb/day
             'avg                                  -
                 = plant loading, 7 lV day/1000 ft
        adjusted
                            V =      (1000)


                            V =  35,700 ft3

    (6)   Determine the  oxygen requirements.

    (a)   For nitrification
where

                          = oxygen required for nitrification, Ib/day

                          = peak ammonia load, 500 Ib/day
                     (0 )   =
                      2^N
                 /NH -N^
                 V  3  /
                        p
    Percent nitrification = 60 percent
                         A
     (b)  For BOD-removal
                               = 1371 Ib/day
                             = 1.5(BODC)Q   (8.3*0
                         BOD          5  aVg

where

            = oxygen required for BOD removal, l"b/day
     /O \
     V  /
        BOD
       BOD  = influent BOD  from secondary treatment, 30 mg/£

       Q    = average flow, 1.0 mgd
        a. V Q


                                7-269

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EM 1110-2-501
Part 1 of 3

29  Sep  78

                               = 1.5(30)1.0(8.3U)
                        (0 )
                        V  /BOD
                               = 375- 3 Ib/day
                           BOD
    (c)  0  =
            = (0 )  +  (0 )
              V ^/N    V VBOD
                             02 = 1371 + 375


                             02 = 17U6 Ib/day


     (7)  Design aeration system (diffused).

     (a)  Assume the following design parameters

    !_  STE = 7 percent

    2_  a = 0.9

    1  3 = 0.9

    h_  p = 1.0

    (b)  Select summer operating temperature and determine 0  satura-
tion (C \   = 8.2 mg/£ .                                     2
         PS
    (c)  Adjust standard transfer efficiency to operating conditions.


                             L V  / T      ^ I      T1 on
                   OTE = STE ——	 al.02


where

      OTE = operating transfer efficiency,  percent

      STE = standard transfer efficiency,  7 percent

     -s)  =8.2 mg/£

        e = 0.9
                                7-270

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                                                           EM 1110-2-501

                                                             Part  1  of 3


                                                               29  Sep 78

        p =  1.0


       C  =  minimum dissolved oxygen,  0 mg/£
        L


        a =  0.9


        T =  25°C



              OTE = T>0 [8.2(0.9)1.0 - 0.0]  0.9(1.02)25-20





                               OTE = 5.6%
    (d)  Calculate required air flow.
                         Ra   OTE(0.



where



     R  = required air flow, cfm/1000 ft
      cL


     0  = oxygen required, 17^6 l"b/day



    OTE = 5.6 percent



      V = volume of tank, 35,700 gal
                      R  =
                       a   5.6(0.0176)1^0(35,700)



                         R  = 258 cfm/1000 ft3
                          a	



    (8)  Determine sludge production.




                                         nitrification A
                                             100      /
                                  avg
                                7-271

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 EM 1110-2-501
 Part  1  of  3
 29 Sep 78

 where

                 A   = sludge produced, Ib/day
                   a
           /NH -U\    = average ammonia load, 250 Ib/day
           V     /avg
      % nitrification = 60%

                            A   = 0.1(250) •$-
                             xa            100


                            AX  = 15 Ib/day
                              a
     (9)  Determine lime requirements for winter
                  Lime = 5.UHH -N)   (* nitrification\
                                   avg        '
                          Lime = 5-M250) ~


                            Lime = 810 Ib/day
    "b.  Denitrification.
    (1)  Calculate WO  loading.
= /NO
                        (NO \  = /
                        \  3/p   \
where
    V °3)    = avera§e N0^ loading, Ib/day
    ^   /avg             -^
        Q    = average flow, 1.0 mgd


                                7-272

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                              29 Sep 78
          \  = peak'NO  loading, Ib/day

          Q  = peak flow, 2.0 mgd


                        (NO \    = 30(1.0)8.sU
                         \   /avg

                          (NO \    = 250  It/day
                          \   /avg	
                                  =500 Ib/day
                                £	

    (2)  Determine NO  loading from Table 7-13.


                        NO  = 18 lb/day/1000 ft3

    (3)  Adjust pH to operating conditions.   Assume pH = 7-0,  therefore,
optimum conditions.

    (k)  Calculate volume of denitrification tank.

                              Ib NO /day
                          V = ————:	 1000
                              NO  loading


where

              V = volume of denitrification  tank,  ft

     Ib NO /day = (NO \  = 500 Ib/day
                       p           ^
    NO  loading = 18 lb/day/1000 ff3
                             v =     (100Q)


                             V ^ 27,778 ft3
                                7-273

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EM 1110-2-501
Part 1 of 3
  29  Sep  78

     (5)  Calculate methanol (carbon) requirements.

                Methanol (ib/day) = 2.5 Ib/lb NO  reduced,

                                  =2.5 (NO \    (% NO  reduced)
                                        V  -Vavg      J
                                  = 2.5(250)

                         Methanol = 625 Ib/day

     (6)  Determine sludge production

                     A   =0.2 Ib/lb methanol added
                      A
                       a
    or
                     A   =0.7 Ib/lb N0_ reduced
                      Xa               3

                     AX  = 0.2(625)
                       a

                     AX  = 125 Ib/day
                       a
7-97-  Cost Data.  Appropriate cost data and economic evaluation may be
found in Chapter 8 .

T-98.  Bibliography.

    a.  Borchardt , J. A., "Nitrification in the Activated Sludge
Process," The Activated Sludge Process, Bulletin, University of
Michigan, Ann Arbor, Mich.

    b.  Brown and Caldwell, Engineers for EPA, "Nitrification and De-
nitrification Facilities," May 7-9, 197^, U. S. Environmental Protection
Agency Technology Transfer, Orlando, Fla.

    c.  Eckenf elder, W. W. , Jr., "General Concepts of Biological Treat-
ment," Manual of Treatment Processes, Vol 1, 1969, Environmental Science
Services, Inc., Briarcliff Manor, New York.

    d.  McCarty, P.  L. , "Biological Processes for Nitrogen Removal:
Theory and Application," Proceedings, Twelfth Sanitary Engineering
Conference, 1970, University of Illinois, Urbana, 111.


                                7-27^

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                                                           EM 1110-2-501
                                                             Part 1 of 3

                                                               29 Sep 78
    e.  Mechalas, B. J., Allen, P. M., III, and Matyskiela, W. W., "A
Study of Nitrification and Denitrification," Report No.  17010DRD,
Jul 19TO, U. S. Environmental Protection Agency, Washington, D. C.

    f.  Metcalf and Eddy, Inc., Waste-water Engineering;  Collection,
Treatment, and Disposal, McGraw-Hill, New York, 1972.

    g.  Moore, S. F. and Schroeder, E. D., "An Investigation of the
Effects of Residence Time on Anaerobic Bacterial Denitrification,"
Water Research, Vol h, No. 10, 1970, pp 685-69^.

    h.  Mulbarger, M. C., "Nitrification and Denitrification in Acti-
vated Sludge Systems," Journal, Water Pollution Control  Federation,
Vol 43, Oct 1971, PP 2059-2070.

    i.  Sawyer, C. N., "Nitrification and Denitrification Facilities,"
Aug 1973, U. S. Environmental Protection Agency, Technology Transfer,
Washington, D. C.

    j.  Seedel, D. F. and Criter, R. W., "Evaluation of  Anaerobic De-
nitrification Processes," Journal, Sanitary Engineering  Division,
American Society of Civil Engineers, Vol 96, No. SA2,  1970.
                                 7-275

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EM 1110-2-501
Part 1 of ^
  29  Sep  78
               Table 7-1.  Effect of pH on Denitrification


             	p_H	                Condition

             At 6.5 <_ pH <_ 7-5                Optimum

             At 6.3 1 PH 1 6.5)
                 ;. 6  <_ pH  <_ 6.3 }
                 ' -1  1 PH  1 8-6/
                                                   of optimum
             At 7-5 < PH  <  7.7)
At 5-6 <_ pH <_ 6.3'
                                 50^ of optimum
                 , \
At 1.
                                  7-276

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                              29 Sep  78

                     Section XIV.  AEBOBIC DIGESTION

7-99-  Introduction.

    a.  Both aerobic and anaerobic digesters are being used in new de-
signs for activated sludge systems; there are advantages and disadvan-
tages to both systems.   Before a specific choice can be made, waste
characteristics, general climatic conditions, type of sludge handling
equipment, and the capacity of the facility must be considered.   In a
large facility, it may be feasible or desirable to digest primary sludge
anaerobically, and secondary sludge aerobically.

    b.  Aerobic digestion is relatively new, and reliable information
on process kinetics and economics is scarce.

    c.  The aerobic combustion of the sludges is usually depicted as
follows .
The NH  in the presence of oxygen can be further oxidized to  NO  to NO

    d.  Advantages claimed for aerobic as compared with anaerobic
digestion are listed below.

    (l)   VSS is reduced to 40-50 percent — nearly equivalent to  that
for anaerobic .

    (2)   Supernatant has lower BOD.

    (3)   A relatively stable humuslike end product is  produced.

    (U)   More basic fertilizer values are recovered.

    (5)   Operation is relatively simple.

    (6)   Capital cost is lower.

    ( 7 )   Odor i s minimal .

    (8)   Sludges dewater well (this  is a controversial statement).

    e.  The major disadvantages  appear to be:


                                 7-277

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EM 1110-2-501
Part 1 of 3
 29 Sep 78

    (1)  A higher operating cost associated with 0  supply.

    (2)  The lack of a useful by-product (no CH, ).

7-100.  Background.

    a.  This -nethod of digestion is capable of handling waste activated,
trickling filter, or primary sludges as well as mixtures of the same.
The aerobic digester operates on the same principles as the activated
sludge process.  As food is depleted, the microbes enter the endogenous
phase and the cell tissue is aerobically oxidized to CO , HO, NH   NO ,
and NO .                                                ^   ^     32

    b.  Up to 80 percent of the cell tissue may be oxidized in this
manner; the remaining fractions contain inert and nonbiodegradable mate-
rials.  Factors to be considered during the design process are character-
istics (orig.in(s)) of the sludge hydraulic residence, true solids load-
ing criteria, energy requirement for mixing, environmental conditions,
and process operation.

7-101.
        Sludge production.
    (, 1)  Pr i nary,  Ib / day.

    (2)  Secondary, Ib/day.

    b.  Solids contents (percent solids).

    (1)  Primary,  percent.

    (2)  Secondary, percent.

    c.  Specific gravity.

    d.  Volatile solids content, percent.

7-102.  Design Parameters  (Table J-2).

7-103-  Design Procedure.

    a.  Calculate total quantity of raw sludge.



                                7-278

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                                                           EM 1110-2-501

                                                             Part 1 of 3


                                                              29  Sep  78




             Q  = _ SP(IOO) _

              s   (specific gravity ) (percent solids) (8. 3^)




vhere




    Q  = volume of raw sludge to digester, gal/day
     S



    SP = sludge produced, Ib/day




    b.  Select hydraulic detention time and calculate digesters'  volume.





                               V = (t)(Q )
                                        S


where




     V = volume of digester, gal




     t = hydraulic detention time, days




    Q  = volume of raw sludge to digester, gal/day
     S


    c.  Check volatile solids loading.
                   VS£ =        VS (7.U8) < (0.1-0.2)




where



    VS£ = volatile solids loading, Ib VS/ft3/day



      V = volume of digester, gal



    d.  Calculate solids retention time.



    (l)  Assume percent destruction of volatile solids:   Uo percent is

common but it increases with temperature  and retention time from approxi

mately 33 to JO percent.



    (2)  Calculate solids accumulation per day.





             S   - qp   qp (f> volatile W^ destroyed \ ,     ,
             Sac - SP - SP ^   10£)    ^    100    ) (0'T5)
                                7-279

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EM 1110-2-501

Part 1 of 3

29 Sep 78



where



    S   = solids accumulated per day
     3,C


     SP = sludge produced



    (3)  Assume MLSS in digester and calculate total capacity of sludge

digester.



                       DC = (V)(MLSS)(8.3^)(10~6)



where



      DC = digester capacity, It



       V = volume of digester, gal



    MLSS = mixed liquor SS in digester, mg/&



    (4)  Calculate solids retention time.
                                      ac

where



    SRT = solids retention time, days



     DC = digester capacity, Ib



    S   = total solids accumulated, lb/day
     £LC


    e.  Calculate sludge wasting schedule.  Assume solids content in

digested sludge is approximately 2.5 percent.



   „-,     -,-,-,   ,   ,      .   ,   total sludge in digester (lb)(lOO)
   Volume of sludge to be wasted = -, - — - fi - — — ff~s - TTT — WQ _< \
                                   (specific gravity )(% solids )( 8. 34)




This volume must be wasted each SRT.



    f.  Calculate oxygen requirements.



    (l)  0  required for bacterial growth.  Assume 0  required per

pound of volatile solids destroyed.





                                7-280

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                                                           EM 1110-2-501

                                                             Part 1 of  3

                                                              29 Sep 78
                 n  -  fn  IQP (% volatile\{% destroyed *

                 °2 ~  (VSP V100A100
                                                     V



where



    0  = total oxygen required, lb/day



    OT = oxygen required/lb of volatile solids destroyed =a 2.0 Ib



    SP = sludge produced, lb/day



    (2)  Energy for mixing.



    (a)  Assume standard transfer efficiency, percent.



    (b)  Assume constants  a ,  3 ,  and  p .



    (c)  Select summer temperature T.



    (d)  Calculate operating transfer  efficiency.
                  OTE = STE




where




      OTE = operating transfer efficiency, percent




      STE = standard transfer efficiency, percent (5-




          = 02 saturation at the summer temperature



        3 = (C  waste/C  water) wO.9
              s        s


        p = correction for altitude ad.O




       C  = minimum oxygen to be maintained in the digester,  mg/£



        a = (1C.   waste/K   water) sdO.9
              J_jcl        lj£L


      K_   = oxygen transfer coefficient
       Ijcl


        T = temperature, °C





                                7-281

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EM 1110-2-501
Part 1 of 3                                 +
 29 Sep 78

    (e)  Calculate air supply;  check against a minimum of
20 cfm/1000 ft3.

                                0 (
                 S           /         Ib Or
                     (OTE %) I 0.0176 —-—-
                             \        ft  air/
-where

     R  = air supply, cfm/1000 ft'3
      S

     02 = oxygen supply, Ib/day

    OTE = operating transfer efficiency, percent

      V = volume of the basin, gal

7-10H.  Output Data.

    a.  Raw sludge specific gravity.

    b.  Detention time, days.

    c.  Volatile solids destroyed, percent.

    d.  Mixed liquor solids, mg/£.

    e.  Solids in digested sludge, percent.

    f.  Rate constant, BOD  applied to filter.

    g.  Coefficient of 0  saturation in waste/0p saturation in water.

    h.  Standard transfer efficiency, percent.

    i.  Digester volume, gal.

    j.  Volatile solids loading, Ib VS/ft3/day.

    k.  Solids accummulated, Ib/day.

    1.  Volume of wasted sludge, gal.

    m.  Solids retention time, days.

                                7-282

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                                                           EM 1110-2-501

                                                             Part  1 of 3

                                                              29 Sep  78
    n.   Oxygen requirement, Ib/day.



    o.   Air supply, cfm/1000 ft3.



7-105.   Example Calculations.



    a.   Calculate total quantity of raw sludge.




                   	SP(IOO)
               s   (specific gravity)(percent solids)8.:


where



                  Q  = volume of raw sludge,  gpd
                   s


                  SP = sludge produced, 2191  It/day



    Specific gravity =1.05



      Percent solids =1.0




                           n  _   2191(100)
                           ^s   1.05(1.0)8.3U




                             Qn = 25,020 gpd
                              S



    b.  Select detention time and calculate digester volume.




                                 V= Qst



where



     V = volume of digester, gal



    Q  = quantity of raw sludge, 25,020 gpd
     S


     t = detention time, 15 days




                             V = 25,020(15)




                             V = 375,300 gal




                                7-283

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 EM 1110-2-501
 Part  1 of 3
 29  Sep  78

    c.   Check volatile  solids loading.
 where

    VS^ = volatile  solids loading, Ib VS/ft3/day

     VS = SP($ volatile) = 2191 (0.80) = 1753 Ib/day

      V = volume of digester
                         VS^ = 0.035 < 0.1  (OK)

    d.  Calculate solids retention time.

    (1)  Assume percent reduction = 50 percent

    (2)  Calculate solids accumulation per day

              S   = SP - SF ft volatile)(# destroyed)
               ac          \   100    'V    100    '
where

            S   = solids accumulation,  l"b/day

             SP = sludge produced, 2191 Ib/day
     % volatile = 80$

    % destroyed =50$
                            S   = 153^ Ib/day
                             cLL-

    (3)  Assume MLSS in digester and calculate total capacity of
digester.
                        DC = V(MLSS)(8.3^ x io~6)

                                 7-28^

-------
where



      DC = digester  capacity, Ib



       V = volume of digester, 375,300 gal



    MLSS = 12,000 mg/£





                    DC = 375,300(12,000)(8.3^ x io~6;




                             DC = 37,560 Ibs



    (4)  Calculate solids retention time



                                      DC
                               SRT =
                                     S
                                      ac
                                                           EM 1110-2-501

                                                             Part 1 of 3


                                                              29 Sep 78
where



    SRT = solids retention time, days



     DC = digester capacity, 37,560 Ib



    S   = solids accumulation, 1,534 Ib/day
     ac


                             qRm _ 37,560

                             SRT "  1,534



                             SET = 24.5 days




    e.  Calculate the sludge wasting schedule.





    Volume of sludge to be wasted = 7	—	—.-.  > ,a	TTT—r 8.34
                  to                 (specific gravity)(% solids)



where



                  DC = digester capacity = 37,560  Ib



    Specific gravity =1.05



            % solids =2.5%





                                7-285

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 EM 1110-2-501
 Part  1  of  3
 29 Sep 78


             Volume of sludge to be wasted =  .3,7,560(100)
                                             1.05(2. 5)8. 31*

               Volume of sludge to be wasted = 171,566 gal


                       Waste every SRT =2^.5 days

    f.  Calculate oxygen requirements.

    (1)  02 required for bacterial growth.  Assume 0  required/lb VS
 destroyed =2.0.                                    2


          Total 02 required = 2.0(SP)(* Y°oQtile)(* destroyed)


                Total 02 required = 2 . 0 ( 2191 )
                     Total 0  required = 1753 Ib/day
    (2)  0  required for mixing (diffused aeration).
                OTE = STE

where
      OTE = operating transfer efficiency, percent

      STE = standard transfer efficiency,  8 percent
        e = 0.9

        P = i.o

       :L = 2<0
        a = 0.9

        T = 25°C


                                7-286

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                              29 Sep  78

                       [8.2(0.9)1.0 - 2.0] lr
               OTE = 8
                              "•-L l
                               OTE =
    Check for mixing >_ 20 cfm/1000 ft3

                         - °2 required
                         ~
                       s ~    OTE(0.01T6)lUUo(V)

where

             R  = air supply, cfm/1000 ft3
              S
    0  required = 1753 lb/day

              V = volume of digester, 375,300 gal

            OTE = \,1%

                             1,753(7.^8 x io5)
                     R  =
                      s   1^7(0.0176)1^0(375,300)

                     R  =29-3 cfm/1000 ft2 > 20  (OK)
                      s_	

7-106.  Cost Data.  Appropriate cost data and economic evaluation may
be found in Chapter 8.

7-107.  Bibliography.

    a.  American Society of Civil Engineers and the Water Pollution
Control Federation, "Sewage Treatment Plant Design," Manual of Practice
No. 8, 1959, 1961, 1967, 1968, Water Pollution Control Federation,
Washington, D. C.

    b.  Burd, R. S., "A Study of Sludge Handling and Disposal," Publi-
cation WP-20-it, May 1968, Federal Water Pollution Control Administration,
Washington, D. C.

    c.  College of Engineering, Oklahoma State University, "Aerobic
Digestion of Organic Wastes," Report No. 17070DAU, Dec 1971, U. S.
Environmental Protection Agency, Washington, D. C.

                                7-287

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EM 1110-2-501
Part 1 of 3
 29 Sep 78

    d.  Dick, R. I., "Sludge Treatment, Disposal, and Utilization     /
Literature Review," Journal, Water Pollution Control Federation, Vol 1*3,
Jun 1971, PP 113U-11U9.

    e.  Drier, D. E., "Aerobic Digestion of Solids," Proceedings of l8th
Purdue Industrial Waste Conference, 1963, Purdue University, Lafayette,
Ind.

    f.  Drier, D. E., "Aerobic Digestion of Sludge," paper presented
at Sanitary Engineering Institute,. Mar 1965, University of Wisconsin,
Madison, Wis.

    g.  Eckenfelder, W. W.,  Jr., Water Quality Engineering for Practic-
ing Engineers, Barnes and Nobel, New York, 1970.

    h.  Great Lakes-Upper Mississippi River Board of State Sanitary
Engineers, "Recommended Standards for Sewage Works (Ten States
Standards)," 1971, Health Education Service, Albany, N. Y.

    i.  Jaworski, N., Lawton, G. W., and Rohlich, G. A., "Aerobic Sludge
Digestion," International Journal of Air and Water Pollution, Vol k,
1961, pp 106-llU.

    j .  Loner, R. C., "Aerobic Digestion-Factors Affecting Design," 9th
Great Plains Sewage Works Design Conference, Mar 1965.

    k.  Lynam, B., McDonnell, G., and Krup, M., "Start-up and Operation
of Two New High-Rate Digestion Systems," Journal, Water Pollution Con-
trol Federation, Vol 39, Apr 1967, pp 518-535.

    1.  Malina, F. J., "Aerobic Sludge Stabilization," Manual of Treat-
ment Processes, Vol 1, Environmental Science Services, Inc., Briarcliff
Manor, New York, 1969.

    m.  McKinney, R. E. and O'Brien, W. J., "Activated Sludge - Basic
Design Concepts," Journal, Water Pollution Control Federation, Vol ho,
Nov 1968, pp 1831-181+3.

    n.  Metcalf and Eddy, Inc. , Wastewater Engineering; Collection,
Treatment, and Disposal, McGraw-Hill, New York, 1972.

    o.  Pohland, F. G. and Kang, J. J., "Anaerobic Processes," Journal,
Water Pollution Control Federation, Vol U6, No. 6, 1971, pp 1129-1133.
                                7-288

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                                                           EM 1110-2-501
                                                             Part  1  of 3
                                                              29 Sep 78

    p.  Sawyer, C.  N.  and Grubling,  J.  S.,  "Fundamental Considerations
in High Rate Digestion," Journal,  Sanitary  Engineering Division, Ameri-
can Society of Civil Engineers, Vol  86, Mar I960,  pp 49-63.

    q..  Shindala, A. and Bryme, W. J.,  "Anaerobic  Digestion of Thickened
Sludge," Public Works, Vol 101, Feb  1970, pp 73-76.

    r.  Shindala, A.,  Dust, J.  V., and  Champion, A.  L., "Accelerated
Digestion of Concentrated Sludge," Water'and Sewage  Works,  Vol 117,
Sep 1970, pp 329-332.
                                7-289

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EM 1110-2-501
Part 1 of 3
 29 Sep 78
             Table 7-2.  Aerobic Digestion Design Parameters
                     ParameterValue
Hydraulic detention time, days at 20°C
  Activated sludge only                                        12 to l6
  Activated sludge from plant operated without
    primary settling                                           16 to 18
  Primary plus activated or trickling-filter sludge            18 to 22

Solids loading, Ib volatile solids/ft /day                    0.1 to 0.2

Oxygen requirements
  BOD  in primary sludge, Ib/lb cell tissue                       =2

Energy requirements for mixing
  Mechanical aerators, hp/1000 ft                             0.5 to 1.0
  Air mixing, cfm/1000 ft^                                     20 to 30
  Dissolved oxygen level in liquid,  mg/H                        1 to 2

Q
   Detention times should be increased for temperature  below 20°C.   If
  sludge cannot be withdrawn during  certain periods (e.g.  weekends,
  rainy weather), additional storage capacity should be provided.  Am-
  monia produced during carbonaceous oxidation is  oxidized to nitrate.
                                T-290

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                              29 Sep 78
                    Section XV.  ANAEROBIC DIGESTION
7-108.  Background.

    a.  This type of digestion can be traced back to the l850's.  The
mechanics involved in the process are summarized in Figure 7-15.  Anaer-
obic digestion may be adapted to both stationary and mobile systems for
handling solids from waste treatment systems, trailer dump stations,
marine dump stations, and vault toilets.
                                 SLUDGE
                       INSOLUBLE ORGANIC MATERIAL
                        SOLUBLE ORGANIC MATERIAL
                                     EXTRACELLULAR
                                        ENZYMES
                                     ACID-PRODUCING
                                        BACTERIA
                                     .  OTHER   .
                                     '  PRODUCTS "*
BACTERIAL
  CELLS
                                              ENDOGENOUS
                                              METABOLISM
                                            TO END PRODUCTS
               Figure 7-15-  Mechanism of anaerobic sludge
                         digestion (Eckenfelder).

    b.  There are conventional and high-rate digesters; the conventional
design uses the one- or two-stage process.  In any of these systems,
provisions are normally made for sludge heating.   The principal differ-
ence in the one- and two-stage systems is that, in the two-stage systems,
digestion is accomplished in the first tank.  Figures 7-l6 and 7-17 con-
tain a pictorial explanation of the system.

    c.  The advantages of anaerobic as compared with aerobic digestion
include:
                                7-291

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EM 1110-2-501
Part 1  of 3
29 Sep  78
                  SLUDGE
                  INLETS
                               GAS STORAGE
                              ~ SCUM LAYER!_
                               SUPERNATANT
                                 LAYER
                                ACTIVELY
                                DIGESTING
                                 SLUDGE
                                              GAS REMOVAL
   SUPERNATANT
    OUTLETS
                                           From Metcalf and Eddy
                  Figure 1-1.6.  Schematic  of conventional
                  digester used in the  one-stage process.
        FIXED COVER
SLUC
INL
SLUDGE
HEATER
GE ^
ET ~*~

MIXER
_(
^ V
— * —
r ^
                              DIGESTER GAS OUTLET
                                                           FLOATING COVER
                                                          (OFTEN UNCOVERED)

^
••*-

SCUM LAYER
SUPERNATANT
LAYER
DIGESTED
SLI I nr;P
                                                          "^SUPERNATANT
                                                          "*"j   OUTLETS


                                                            I  SLUDGE
                                                            | OUTLETS
                  FIRST STAGE
               (COMPLETELY MIXED)
SECOND STAGE
 (STRATIFIED)
                                                        From Metcalf and Eddy
                   Figure 7-17.  Schematic  of two-stage
                             digestion process.

     (l)  Higher  organic loading, i.e. rates  of treatment not limited
"by 0  transfer.

     (2)  Minimal need for biological nutrients '(N and P) and for  further
treatment .

     (3)  Lover energy requirement.
         Production of a useful by-product  (CH, )  which has a low  heat
value compared to natural gas.

    d.  The  disadvantages are as follows:

                                 7-292

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                                                           EM 1110-2-501
                                                             Part  1 of 3
                                                             29 Sep 78 '

    (l)  Digesters must be heated to 85-90°F for optimum operation.

    (2)  Molecular oxygen is toxic to the system and must be excluded.

    (3)  Fundamental knowledge concerning the process is sparce.

    (h)  Highly skilled operation is required.

    (5)  Anaerobic digesters are easily upset by unusual conditions and
are slow to recover.

    (6)  Recycled supernatant liquor tends to "shock" wastewater treat-
ment facilities.

    (7)  The fact that a closed vessel is required complicates  the
inevitable cleaning necessary.

    (8)  The recovered gas, while useful, increases initial costs
because of the necessity of providing explosion-proof appurtenant
equipment.

    (9)  Digested sludge tends to be high in alkalinity.  Where vacuum
filtration preceded by chemical coagulation with the usual inorganic
chemicals is practiced, increased chemical costs are inevitable.

7-109.  Input Data.

    a.  Sludge production, Ib/day.

    (l)  Primary.

    (2)  Secondary.

    b.  Volatile solids in raw sludge, percent.

    c.  Solids content in raw sludge, percent.

    (1)  Primary.

    (2)  Secondary.

    d.  Volatile solids destroyed during digestion, percent
60 percent).
                                7-293

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EM 1110-2-501
Part 1 of 3
29 Sep 78
    e.  Fixed solids produced from destruction of volatile  solids,
        '      \:
percent (s£.25(X ) destroyed).

    f.  Solids concentration in digester, percent («3-7 percent).

7-110.  Design Parameters.

    a.  Desired digester temperature, °F.

    b.  Temperature of fresh sludge, °F.

    c.  Digestion time, days.

    d.  Gas production per pound of volatile solids destroyed, ft /lb


    e.  Heat value of gas produced, BTU/ft  («61|0).

7-111.  Design Procedure.

    a.  Calculate total volume of raw sludge to digester.


                v  = 	SP(IOO)	
                 f   (% solids)(62.b)(specific gravity)

where
                                             o
    V  = volume of raw sludge to digester, ft /day

    SP = sludge produced, Ib/day

    b.  Calculate total quantity of solids accumulated after digestion.


          Sac = SP - BP(% volatile)($ VS destroyed)(0.75)(10"^)

where

    S   = solids accumulated, Ib/day
     Q.C

     SP = sludge produced, Ib/day

    c.  Calculate total volume of digested sludge; assume  solids con-
centration in digester.

                                7-29U

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                                                           EM 1110-2-501

                                                             Part 1 of 3


                                                                29  Sep 78
                V, =
                                  Sac(l°°;
                        solids)(62.U)(specific gravity)
where
     V, = volume of digested sludge, ft"/day
      d


    S   = solids accumulated, Ib/day
     ac


    d.  Select the detention time for destruction of volatile solids

at a temperature of 95°F (fig. 7-18).



    e.  Calculate the average volume in the digester.
                                    Vf + Vd
                              avg
                  10     20     30     40     SO      60     70

                  DETENTION, DAYS, BASED ON RAW SLUDGE FEED



               Figure 7-l8.  Reduction in volatile solids

               in raw sludge, for detentions from 15 to

                          70 days, T = 85 to 95°F.
                                7-295

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 EM 1110-2-501

 Part 1 of 3

 29 Sep 78



 where




    Va   = average volume in digester, ft /day




      Vf = volume of fresh sludge added, ft^/day




      Vd = volume of accumulated sludge after digestion, ft3/day



    f.  Calculate volume of digester.





                              V = V   (t,)
                                   avg  d


where
  V = volume in digester, ft




a
    Va   = average volume in digester, ft /day
      t^ = digestion time, days




    g.  Calculate heat requirements.




    (1)  Heat supplied must be sufficient to raise the temperature of

the incoming sludge to 95°F.






               Qs = (SP/Ps) x (c) x (Td - Tg)(1/210(100)




where




    Q  = BTU/hr required
     s



    SP = sludge added per day, l~b




    P0 = solids in fresh sludge,  percent
     S



     C = 1.0 BTQ/ft2/day/°F




    T  = temperature of sludge in digester = 95°F




    Ts = temperature of incoming  sludge, °F




    (2)  Heat losses are as follows.




                               7-296

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                              29 Sep 78

    (a)  Heat loss through the walls of digester.


                            Ov = UA(T2 - TI)

where

    Q  = heat loss, BTU/hr

     U = heat loss coefficient, BTU/hr/ft2/°F (*0.l8)
                                  2
     A = surface area involved, ft

    T  = temperature within digester, °F

    T  = average temperature of coldest 2 weeks of a given year, °F

    (t>)  Heat losses through the floor.


                            Qf = UA(T2 - TX)


    (c)  Heat losses through the digester cover.


                            Qc = UA(T2 - Tx)


Heat requirements = (l_ + 2_) BTU/hr.

    h.  Calculate daily gas production.  Assume volume of gas produced
per pound of volatile solids destroyed (12-18 ft3/lt>).


    DGP = (SP)($ volatile)($ destroyed)(10~  )(ft3/rb gas production)
where
                                2
    DGP = daily gas produced, ft /day

     SP = sludge produced, Ib/day

    i.  Calculate daily gas requirement.  Assume heat value of gas:
600 BTU/ft3 for digester gas; 1000 BTU/ft3 for natural gas.


                                7-297

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EM 1110-2-501
Part 1 of 3
 29 Sep 78
                        _  heat requirement (BTU/hr)

                          heat value of gas (BTU/ft3)
where  DGR = daily gas requirement, ft /hr

7-112.  Output Data.

    a.  VS destroyed, percent

    "b.  Solids concentration in digester, percent.

    c.  Raw sludge temperature, °F.

    d.  Digester temperature, °F.

    e.  Detention time, days.

    f.  Volume, ft3.

    g.  Gas produced, ft /day.

    h.  Heat requirement, ft /hr.
                                    O
    i.  Digester gas requirement, ft /hr.

7-113.  Example Calculations.

    a.  Calculate total volume of raw sludge to digester.


                 v  = 	SP(IOO)	
                  f   (% solids)(62.4)specific gravity

where

                  V  = volume of sludge, ft /day

                  SP = sludge produced, 2191 Ib/day

            % solids = 1 percent

    Specific gravity =1.05


                                7-298

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                                                           EM 1110-2-501

                                                             Part  1  of  3

                                                               29 Sep 78




                            V  -  2191(100)

                             f ~ 1(62.101.05




                            Vf = 33hU ft3/day




    b.  Calculate total volume of solids accumulated after digestion.





          S   = SP - SP(% volatile)(% VS destroyed)0.75 x 10
where
               S   = solids accumulated, l"b/day
                £LC


                SP = solids produced, 2191 Ib/day



        % volatile = 80



      VS destroyed = 60
                 S   = 2191 - 2191(80)(60)(0.75 x 10
                  £LC



                            S   = 1)402 Ib/day
                             ac	



    c.  Calculate total volume of digested sludge.
                                  S  (100)

                  V, =
                   d   % solids(62.U)specific gravity




where


                                                    •3

                  V  = volume of digested sludge, ft /day



                 S   = solids accumulated, 1^02 Ib/day
                  ac


            % solids = 5 percent



    specific gravity = 1.05






                                7-299

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EM 1110-2-501
Part 1 of 3
  29  Sep  78

                            V  =  1402(100)
                             a   5(62.4)1.05
                            V  = 428 ft3/day

    d.  Select the detention time for destruction of volatile solids at
a temperature of 95°F.  Detention time = 28 days = t  .
                                                    d
    e.  Calculate the average volume in the digester.

                                    V  + V
                             V    = -£	I*
                              avg      2
where
                             o
    V    = average volume, ft /day
      V  = volume of raw sludge to digester, 3344 ft /day
      V  = volume of digested sludge, 428 ft /day

                            v      3344 + 428
                            V    = 	
                             avg        2

                                = 1886 ft3/day

    f.  Calculate volume of digester.

                              V = V   (t,)
                                   avg  d
where
                                 •3
       V = volume of digester,  ft
    V    = daily volume in digester, 1886 ft /day
      t  = detention time, 28 days

                              V = 1886(28)
                            V = 52,808 ft3
                                7-300

-------
    g.  Calculate heat requirement.



    (l)  Heat required
where
    Q  = BTU/hr required
     S


    SP = sludge added per day, 2191 Ib



    P  = solids in fresh sludge, 1%
     S


     C = constant, 1.0 BTU/ft2/day/°F



    T  = temperature of sludge in digester, 95°F



    T  = temperature of incoming sludge,  70°F
     S
                   Qs =        d.o)            (100)
                           Q  = 228,230 BTU/hr
                            S
    (2)  Calculate heat losses.



    (a)  Losses through walls




                            ^ = UA(T2 - T^


where



    Q  = heat loss through walls, BTU/hr



     U = heat loss coefficient,  0.18 BTU/hr/ft2/°F


     A = area of walls, h$2k ft2



    T  = temperature in digester, 95°F





                                7-301
                                                           EM 1110-2-501

                                                             Part 1 of 3

                                                              29 Sep 78

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EM 1110-2-501

Part 1 of 3

29 Sep 78


    T  = average temperature of coldest 2 weeks of the year, 10°F



                        ^ = (0.18)4524(95 - 10)



                           0  = 69,217 BTU/hr
    ("b)  Losses through floor.



                           Qf = U(Af)(T2 - Tx
where


    A  = area of floor, l8lO ft2
                       Qf = (O.l8)(l8l0)(95 - 10)
                           Qf = 27,693 BTU/hr
    (c)  Losses through cover.
                              = U(Ac)(T2 -
where

                               o
    A  = area cf cover, l8lO ft
                          = (0.18)(1810)(95 - 10)
                           Qc = 27,693 BTU/hr
    (d)  Total heat losses.
                                      Qf + Qc
where
    Q  = total heat losses, BTU/hr
     "C
                                 7-302

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                                                            EM 1110-2-501
                                                              Part  1  of  3
                                                                29  Sep 78
                       Qt =  69,217 + 27,693 + 27,686
                            Q, = 12^,603 BTU/hr
Total heat requirement = Q  + Q
                          u    S
                       = 12*1,589 + 228,230
                 Total heat requirement = 352,819 BTU/hr
    h.  Calculate daily gas production.
Assume volume of gas produced per pound of volatile solids destroyed =
15 ft3/ib.
           DGP = (SP)($ volatile}(% destroyed)15 x 10   ft3/lb
where
                                        o
            DGP = daily gas produced, ft /day
             SP = sludge produced, 2191 Ib/day
     % volatile = Q0%
    % destroyed = 60%
                      DGP = 2191(80) (60) (15 x 10'14)
                      DGP = 15,775 ft3/day
At 600 BTU/ft3
DGP = 15,775(600)
DGP =  9,^65,000
    i.   Calculate daily gas  requirement.
                          heat requirement (BTU/hr)
                        = 	*	•	—
                          heat value of gas (BTU/ft3
where
                                   p
    DGR = daily gas requirement,  ft /hr
                                  - 352,819
                                  -   600
                                7-303

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EM 1110-2-501
Part 1 of 3
 29 Sep 78
                            DGR = 588 ft3/hr
where DGP or daily gas produced =
                                    ft3/day
                                2U hr/day

                            DGP = 657 ft3/hr

There is sufficient gas produced to heat the digester.

7-111*.  Cost Data.  Appropriate cost data and economic evaluation may
be found in Chapter 8.

7-115.  Bibliography.

    a.  American Society of Civil Engineers and the Water Pollution
Control Federation, "Sewage Treatment Plant Design," Manual of Practice
No. 8, 1959, 1961, 1967, 1968, Water Pollution Control Federation,
Washington, D. C.

    b.  Burd, R. S. , "A Study of Sludge Handling and Disposal," Publi-
cation WP-20-U, May 1968, Federal Water Pollution Control Administration
Washington, D. C.

    c.  College of Engineering, Oklahoma State University, "Aerobic
Digestion of Organic Wastes," Report No. 17070DAU, Dec 1971, U. S.
Environmental Protection Agency, Washington, D. C.

    d.  Dick, R. I., "Sludge Treatment, Disposal, and Utilization
Literature Review, Journal, Water Pollution Control Federation, Vol k3,
Jun 1971, pp
     e.  Drier, D. E. ,  "Aerobic Digestion of Solids," Proceedings of l8th
 Purdue  Industrial Waste  Conference, 1963, Purdue University, Lafayette,
 Ind.

     f.  Drier, D. E.,  "Aerobic Digestion of Sludge," paper presented  at
 Sanitary  Engineering Institute, Mar 1965 s University of Wisconsin,
 Madison,  Wis.

     g.  Eckenf elder, W.  W. ,  Jr., Water  Quality  Engineering for
 Practicing Engineers,  Barnes and Nobel, New York,  1970.
                                 7-30U

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                              29 Sep 78

    h.  Great Lakes-Upper Mississippi River Board of State Sanitary
Engineers, "Recommended Standards for Sewage Works (Ten States
Standards)," 1971, Health Education Service, Albany, N. Y.

    i.  Jaworski, N. , Lawton, G. W., and Rohlich, G. A., "Aerobic Sludge
Digestion," International Journal of Air and Water Pollution, Vol k,
1961, pp 106-111*.

    j.  Loner, R. C., "Aerobic Digestion-Factors Affecting Design,"
9th Great Plains Sewage Works Design Conference, Mar 1965.

    k.  Lynam, B., McDonnell, G., and Krup, M., "Start-up and Operation
of Two New High-Rate Digestion Systems," Journal, Water Pollution Con-
trol Federation, Vol 39, Apr 1967, PP 518-535-

    1.  Malina, F. J., "Aerobic Sludge Stabilization," Manual of Treat-
ment Processes, Vol 1, Environmental Science Services, Inc., Briarcliff
Manor, New York, 1969.

    m.  McKinney, R. E.  and O'Brien, W. J., "Activated Sludge - Basic
Design Concepts," Journal, Water Pollution Control Federation, Vol ho,
Nov 1968, pp 1831-181*3.

    n.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection,
Treatment, and Disposal, McGraw-Hill, New York, 1972.

    o.  Pohland, F. G. and Kang, J. J., "Anaerobic Processes," Journal,
Water Pollution Control Federation, Vol 1*6, No. 6, 1971, pp 1129-1133.

    p.  Sawyer, C. N. and Grubling, J. S., "Fundamental Considerations
in High Rate Digestion," Journal, Sanitary Engineering Division, Ameri-
can Society of Civil Engineers, Vol 86, Mar I960, pp 1*9763.

    q.  Shindala, A. and Bryme, W. J., "Anaerobic Digestion of Thickened
Sludge," Public Works, Vol 101, Feb 1970, pp 73-76.

    r.  Shindala, A., Dust, J. V., and Champion, A.  L., "Accelerated
Digestion of Concentrated Sludge," Water and Sewage  Works, Vol 117,
Sep 1970, pp 329-332.
                               7-305              (next page is 7-307)

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                                                            EM 1110-2-501
                                                              Part  1  of  3
                                                                29 Sep  78
                    Section XVI.  STABILIZATION PONDS
7-116.  Background.
    a-  General.  Waste stabilization ponds have been used extensively
for the treatment of organic and industrial wastes where sufficient land
area is available.  Other reasons for its wide usage include fluctuating
organic loadings, shortage of trained operators for other, more complex
systems, and monetary currency restrictions.  Ponds may be used for a
variety of different applications.  Usually stabilization ponds are de-
signed to receive untreated waste; however, they may also be designed
to treat primary or secondary effluents, excess activated sludge, or
even vault wastes.  Multiple stabilization ponds may be designed for
series or parallel use.  Pretreatment by waste stabilization ponds is
used primarily to reduce BOD loadings and to reduce the concentration
of disease-causing agents (para 7-123f).  For this manual, waste sta-
bilization ponds will be considered as three types:  aerobic, faculta-
tive, and anaerobic.

    b-   Aerobic.  An aerobic stabilization pond is one in which aerobic
bacteria and algae coexist in an aerobic environment (fig.  7-19).   The
                                            From Clark and Viessman, 1965

        Figure  7-19-   Schematic  diagram of  facultative  oxidation
               pond  symbiosis between  bacteria  and algae.

                                7-307

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aerobic stabilization pond depends on algae photosynthesis and atmo-
spheric reaeration to supply the oxygen used by bacteria to stabilize
the organic matter.  Because algae photosynthesis is directly dependent
upon sunlight, pond operating depths are normally limited to 3 feet.  To
maintain aerobic conditions in the settled materials and good oxygen dis-
tribution, the contents of the pond should be mixed periodically.  Solu-
ble BOD<5 removal in aerobic ponds is high (up to 95 percent)-, however,
separation of the algae from the effluent is necessary to obtain a true
BOD5 removal.  The use of aerobic stabilization ponds should be avoided
where the waste to be treated contains materials toxic to algae growth.

    c.  Facultative.  A facultative stabilization pond is characterized
by an upper aerobic layer or zone and an anaerobic bottom.  It is possi-
.ble to find aerobic, facultative, and anaerobic organisms in this type
of pond.  Variation of oxygen content in the aerobic zone is diurnal,
increasing during the daylight hours and decreasing during the night.
The settled sludge undergoes anaerobic decomposition, thus releasing
methane and other gases.  In turn, the aerobic organisms utilize these
gases; therefore, maintaining an aerobic upper zone is essential in
minimizing odor problems.  Normal operating depths range from 3 to 8 ft.

    d.  Anaerobic.  Ana.erobic stabilization ponds are essentially un-
heated digesters.  Loadings induce anaerobic conditions throughout the
pond and the  conversion of organic matter is the same as in anaerobic
digestion.  The acid-forming bacteria convert the organic matter to
organic acids which are further converted to methane gas by the methane
formers.  Pond depths in the range of 8 to 15 ft are used to maintain
anaerobic conditions and to provide maximum heat retention.

7-117•  Input_ Data.

    a.  Wastewater flow.

     (l)  Average daily, mgd.

     (2)  Peak hourly, mgd.

    b.  Wastewater  strength, BOD  mg/&.

     c.  Other characterizations.

     (1)  pH.

     (2)  Temperature  (maximum and minimum).

                                  7-308

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7-118.  Design Parameters.  (See Table 7-3).

7-119-  Design Procedure.  The biochemical relationships existing in
vaste stabilization ponds are very complex.  Several attempts have been
made to develop a completely analytical rationale for the design of
ponds.  However, the complexity has resulted in a design procedure based
on a load per unit area concept.  Experience has shown this to be accept-
able design practice, one often specified by state regulatory agencies.
The following procedure is applicable to all three types of ponds:
aerobic, facultative, and anaerobic.

    a.  Calculate BOD  present in the waste.
                   BOD5 = (Qavg)
where
       BOD  = BOD  in the waste, Ib/day

       Q    = average flow, mgd
        avg
    (BOD  J  = influent BOD , mg/£

    b.  From the design parameters given in Table 7-3, select a BOD;.
loading.

    c.  Calculate the surface area required based on the Ib/day of
BOD  and BOD  loading.

                                    BOD,.
                           SA =
                                BOD  loading
where

              SA = surface area, acres

    BOD  loading = Ib/acre/day

    d.  Select a pond operating depth from Table 7-3 and calculate the
pond volume.


                          V = (SA)(D)(0.32585)


                                7-309

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29 Sep 78
where
          V = pond volume, million gal
         SA = surface area, acres
          D = pond depth, ft
    0.32585 = conversion factor, acre-ft to mg
    e.  Check en the detention time.

                                ,. _  V
                                     avg
where
       t = detention time, days
       V = volume, million gal
Check  t  against the range of values given in Ta~ble 7-3.
    -"".  Sinre design equations are not available, the effluent soluble
BODr is estimated according to the following.
where
    /'BOD \    = effluent BODr., mg/£
          'eff
              = decimal BOD  conversion (from Table 7-3)
              = influent BOD , mg/£
7-120.  Output Data.
    a.  BOD loading, lb/acre/day.
    b.  Surface area, acres.
                                7-310

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                                                              29 Sep 78
    c.  Depth, ft.

    d.  Volume, acre-ft.

    e.  Detention time, days.

7-121.  Example Calculations  (Facultative).

    a.  Calculate BOD  present in waste.
                         BOD5 =
where
       BOD  = BOD  in waste, Ib/day

       Q    = average flow, 1.0 mgd

    (BOD \  = influent BOD  , 200 mg/I


                           BOD  = 1.0(200)8.3^

                           BOD  = 1668 Ib/day

    b.  Select a BOD  loading = 50 Ib/acre/day

    c.  Calculate surface area.
                                    BOD
                           GA = 	2	
                                BOD  loading
where

              SA = surface area, acres

            BOD  = BOD  in waste, 1668 Ib/day
    BOD  loading = 50 Ib/acre/day
                                     1668
                                   "  50
                             SA = 33.it acres

                                 7-311

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 29 Sep 78
    d.  Select a pond operating depth and calculate the pond volume.

                            V = SA(D)0.32585
where
          V = pond volume, million gal
         SA = surface area, 33 A acres
          D = pond depth, 6 ft
    0.32585 = converts acre-ft to million gal

                           v = 33.^(6)0.32585
                          V = 65.3 million gal
    e.  Check detention time.
                                     v
                                t =
where
       t = detention time, days
       V = volume of pond, 65-3 mg
Qavg
    Q    = average flow, 1.0 mgd
                                t _
                                t    1.0
                              t = 65.3 days
    f.  Determine effluent BOD  .

                    (BOD )    = [i -
                    V   -Veff   L
where
    (BOD  )    = effluent BOD , mg/A
    V   -> A-pf               ?
           eff
                                7-312

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      >M30D  J  = decimal BOD  conversion, 0.65
              = influent BOD   200 mg/£
                        (B°D5)
    = (1 - 0.65)200
eff
                           (B°D5)
       = TO mg/£
   eff
7-122.  Cost Data.  Appropriate cost data and economic evaluation may
be found in Chapter 8.

7-123.  Bibliography.

    a.  Barsom, G., "Lagoon Performance and the State of Lagoon Tech-
nology," Report Wo. R2-73-l^, Jun 1973, U. S. Environmental Protection
Agency, Washington, D. C.

    b.  City of Austin, Texas, "Design Guides for Biological Wastewater
Treatment Processes," Report Wo. 11010ESQ, Aug 1971, U. S. Environmental
Protection Agency, Washington, D. C.

    c.  Clark, J. W. and Viessman, W., Jr., Water Supply and Pollution
Control, International Textbook Co., Scranton, 1966.

    d.  Eckenfelder, W. W., Jr., and Ford, D. L., Water Pollution
Control, Pemberton Press, New York, 1970.

    e.  Gloyna, E. F. , "Basis for Waste Stabilization Pond Design,"
Advances in Water Quality Improvements - Physical and Chemical Processes,
E. F.  Gloyna and W. W. Eckenfelder, Jr., ed., University of Texas Press,
Austin, 1970.

    f.  Gloyna, E. F., "Waste Stabilization Ponds," World Health Organi-
zation, Geneva, Switzerland, 1971.

    g.  Great  Lakes-Upper Mississippi River Board of State Sanitary
Engineers, "Recommended Standards for Sewage Works (Ten States Stan-
dards)," 1971, Health Education Service, Albany, W. I.

    h.  Herman, E. R.  and Gloyna, E.  F., "Waste Stabilization Ponds,
III,  Formulation of Design Equations," Sewage and Industrial Wastes,
Vol 30, No.  8, Aug 1958, pp 963-975.


                                7-313

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Part 1 of 3
29 Sep 78

    i.  Marais, G. V. R., "New Factors in the Design, Operation and
Performance of Waste Stabilization Ponds with Special Reference to
Health," Expert Committee Meeting on Environmental Change and Resulting
Impact on Health Organization,
    j.  McKinney, R. E. , "Overloaded Oxidation Ponds -, Two Case Studies,"
Journal, Water Pollution Control Federation, Vol HO, Jan 1968, pp H9-56.

    k.  Metcalf and Eddy, Inc., Wastewater Engineering; Collection,
Treatment, and Disposal, McGraw-Hill, New York, 1972.

    1.  Oswald, ¥. J., "Rational Design of Waste Ponds," Proceedings ,
Symposium on Waste Treatment by Oxidation Ponds , Nagpur, India, 1963.

    m.  Oswald, W. J., "Quality Management by Engineered Ponds," Engi-
neering Management of Water Quality, McGraw-Hill, New York, 1968.

    n.  University of Kansas, "Waste Treatment Lagoons," 2d International
Conference on Lagoon Technology, 1970, Lawrence, Kans.

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Table 7-3.  Design Parameters for Stabilization Ponds
Type of Pond
Parameter Aerobic
Flow regime Intermittently mixed
Pond size, acres <10 multiples
Operation Series or parallel
Detention time, days 10 to 1*0
Depth, ft 3 to U
pH 6.5 to 10.5
Temperature range, °C 0 to 1*0
Optimum temperature, °C 20
^ BODS loading, Ib/acre/day 60 to 120^d'
H ?
VJ1 BOD,, conversion 60 to 70
Principal conversion products Algae, C02> bacterial
cell tissue
Algal concentration, mg/JJ. 80 to 200
Effluent suspended solids,
mg/2>e' ll*0 to 3l*0
Facultative
—
2 to 10 multiples
Series or parallel
7 to 30
3 to 6
6.5 to 9.0
0 to 50
20
15 to 50
60 to TO
Algae, C02, CH^,
bacterial cell
tissue
1*0 to 160
160 to 1»00
Facultative
Mixed surface layer
2 to 10 multiples
Series or parallel
7 to 20
3 to 8
6.5 to 8.5
0 to 50
20
30 to 100
60 to 70
C02, CHjj, bacterial
cell tissue
10 to 1*0
110 to 3l*0
Anaerobic
~
0.5 to 2.0 multiples
Series
20 to 50
8 to 15
6.8 to 7-2
6 to 50
30
200 to 500
50 to 70
C02, CHjj, bacterial
cell tissue
—
80 to 160
v Conventional aerobic ponds designed to maximize the amount of oxygen produced rather than the amount of algae
produced.
Depends on climatic conditions.
Typical values (much higher values have been applied at various loadings). Loading values are often specified
by state control agencies.
Some states limit this figure to 50 or less.
Includes algae, microorganisms, and residual influent suspended solids. Values are based on an influent solu-
ble BODg of 200 mg/fc and, with the exception of the aerobic ponds, an influent suspended-solids concentration
of 200 mg/a. prom Metcalf and Eddy, 1972











'Tl
M 3- H
O
C/5 H 1
•S %^
^J °
oo >> I-1

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                                                           EM 1110-2-501
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                                                              29 Sep  78

                                CHAPTER 8

                     COST DATA AND ECONOMIC ANALYSIS

                        Section I.  INTRODUCTION

8-1.   Economic Analysis.

    a.  As noted previously, cost data are available on the physical-
chemical -biological unit processes which allow the design engineer to
estimate the average capital and operating and maintenance costs for
each process and for a specific design train.   Many alternative  treat-
ment processes and treatment systems can be screened according to cost-
effectiveness analysis procedures with these cost estimates.  Those
systems which meet discharge requirements and are most cost-effective
can be examined in depth with more exact cost estimates reflecting local
variation.

    b.  The cost estimates for the unit processes were obtained  from
the most recent sources available.  These sources are noted in each unit
process cost section ana are referenced at the end of each process.
Some unit processes have no cost data, hence the design team must use
its own judgement in evaluating the costs.  No overall cost estimates
were available for these unit processes.  As revised cost estimates for
known cost information are made available they will be furnished to the
user in the form of changes.  At present, the designers must update the
cost information according to the year it was published.  In this manner
all processes may be judged on the same basis or for the costs for the
same year.  At present all cost data included in this manual have as
their base the year 1971•

    c.  The cost estimates are broken down into two areas:(l) capital
costs and (2) operating and maintenance costs.  Capital cost reflects
all initial construction costs for each unit process.  Estimated costs
of engineering, legal, fiscal, and administrative services, land, and
interest during construction are not included in the capital cost
estimate.  These costs must be estimated separately and added to the
treatment process costs to reflect total system costs.  The operating
and maintenance costs are all labor, materials, and supply costs nec-
essary to operate the processes after construction.

    d.  Most of the cost estimates were obtained by a statistical re-
gression analysis of the cost data from numerous treatment facilities.
Cost equations were formed which related an appropriate physical


                                 8-1

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parameter to the cost.  These equations give estimates of the capital
costs, number of man-hours of labor for operation per year,  number of
man-hours of labor for maintenance per year, and a materials and supply
cost per year.  The physical parameter inputs necessary for  the design
of the unit process are used in the cost equations.  The appropriate
parameter for each cost equation is noted in each cost section.   The
man-hours of labor required per year for both operation and  maintenance
must be multiplied by the average labor wage rate to obtain  an estimate
of operating and maintenance costs.

    e.  After the design engineer performs the initial calculation out-
lined herein, estimates of the capital and operating and maintenance
costs for each unit process in the treatment train will be available.
Environmental Protection Agency (EPA) guidelines for waste-wafer treat-
ment plants state that a cost-effectiveness analysis must be performed
on alternative wastewater treatment systems.  Before a comparison of
treatment systems with different capital and operation and maintenance
costs can be made, an economic analysis recognizing the time value of
money is required.  The present worth method or the equivalent annual
cost method may be used in this analysis.  The Federal discount (in-
terest) rate will be used for evaluation of water and related land re-
sources projects as published in the Federal Register.

    f.  The present worth method determines the sum which represents
capital cost and the present monetary value of the time stream of opera-
tion and maintenance costs for a given interest rate.  On the other
hand, the equivalent annual cost method amortises the capital expendi-
tures at a given interest rate over the design life of the project.
This cost is added to the yearly operation and maintenance costs to
obtain an equivalent uniform yearly cost for the plant.  Once a method
is chosen the design engineer uses the capital operating and maintenance
costs calculated for each alternative wastewater treatment system as
input into the analysis.  Both methods give a true indication of the
total project costs for differing alternative wastewater treatment
systems.  A discussion of both methods as they relate to cost effective-
ness analysis Ls provided by the EPA.

    g.  As part of the overall selection process, the design engineer
will want to consider as many viable treatment alternatives  as possible.
However, the number of possible combinations of treatment processes
which make up a treatment system prevent manual consideration of all
possible systems.  A way to screen alternatives according to their
ability to meet effluent standards and their cost is needed.  The com-
puterized design process outlined in Part 3 gives the design engineer

                                 8-2

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                                                           EM 1110-2-501
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                                                              29  Sep 78
this capability.  For any number of treatment system alternatives, the
computerized design process will screen alternatives to determine which
meet desired effluent criteria and which are the most cost-effective in
relation to monetary costs.  The entire process for the manual calcula-
tion of unit process costs and economic analysis is provided by the
computer.  The alternative treatment trains are presently compared by
the equivalent annual cost method in the computerized design process.
When used to examine all the feasible wastewater treatment plant  designs
in the initial planning stages of a wastewater study the computerized
design process is a powerful tool.
                                 8-3                  (next  page  is  8-5)

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                                                           EM 1110-2-501
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                  Section II.   PHYSICAL UNIT PROCESSES

8-2.   Grit Removal.

    a.   Most available data on cost of waste-water treatment facilities
combine the cost of screening, grit removal, and flow measuring devices
into one cost, referred to as  "preliminary treatment."  In this manual,
the cost of grit removal is combined with the cost of screening as well
as flow measuring devices.  The following cost formulations are those
developed by Patterson and Banker and formulated by Eilers and Smith.

    b.  Cost formulations for preliminary treatment are:


                            CC= 27,500X0'606


                           OHR = 530X°'68U


                           XHR = 301X0'6011


                            su = i,o6ox°'6lU

where

     CC = capital cost, dollars

      X = Q    = average daily flow, mgd

    OHR = annual operating labor, man-hours

    XHR = annual maintenance labor, man-hours

     SU = materials and supplies cost

8-3-  Screening.

    a.  Most  available data on costs of wastewater treatment facilities
combine the cost of screening devices, comminutors, and grit removal and
flow measuring equipment under one heading usually referred to as  "pre-
liminary treatment."  No separate cost data are currently available.
Equipment manufacturers may be consulted with regard to capital and
operating costs of screening devices.
                                 8-5

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Part 1 of 3
 29 Sep 78

    b.  In this manual, the cost of screening is included,  along with
costs for grit removal and flow measuring equipment, and  is referred
to as "preliminary treatment."  Cost equations  for screening are the
same as those listed under grit removal.

8-4.  Comminution.

    a.  Since the size of the commiriutor is determined on the basis of
wastewater flow, cost formulations for the comminutor are also based on
wastewater flow.  Capital cost of equipment only, not including special
housing or concrete structures, has been formulated as follows.

    b.  Cost formulations for comminution are:


                              CC = 580X0'114

where

    CC = capital cost, dollars

     X = Q    = average daily flow, mgd

    c.  Cost data available for wastewater treatment facilities combine
the operating and maintenance costs of screening, comminution, and grit
removal and flow measuring devices under one item normally referred to
as "preliminary treatment."  Currently, no data are available on opera-
tion and maintenance costs of comminuting devices.

8-5-   Egualiz_ation_.  Cost formulations for equalization basins are as
follows:


                            CC - 82X°'61|(lOOO)

                           OHR = 0

                           XHR = 0

                            SU = 3650(0.13^)3(0.02) + 0.035 CC

where

    CC = capital cost, dollars
                                  8-6

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     X = V = volume of tank,  million gal
    SU = materials and supply cost,  dollars
     B = hp = horsepower required
8-6.  Flotation.   Cost formulations  for flotation tanks are as follows:
                           CC = 17,U32X°'5TT3
                          OHR = 0
                          XHR = 0
                           SU = 0.02 CC
where
    CC = capital cost dollars
     X = V = volume of flotation tank, million gal
    SU = materials and supply costs, dollars
8-7.  Thickening (gravity).  Cost formulations for gravity thickening
units are as follows:
                            CC = 3
                           OHR =  ,
                           XHR = 161X°'602
                            SU = U8UX°-U16
where
     CC = capital cost , dollars
     X = TSA = total surface area, sq. ft
    OHR = annual operating labor, man-hours
    XHR = annual maintenance labor, man-hours
     SU = materials and supply cost, dollars
                                  8-7

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 29 Sep 78

8-8.  Sedimentation (Primary Clarifier).  Cost formulations for primary
clarifiers are as follows:


                            CC = 26,120X°'7611

                           OHR = 3UOX°'53

                           XHR = 1T7X°'52

                            SU = 293X°'Tla

where

     CC = capital cost, dollars

           SA
      X = -,     = surface area, sq ft
    OHR = annual operating labor, man-hours

    XHR = annual maintenance labor, man-hours

     SU = materials and supply cost, dollars

8-9.  Sedimentation (Secondary Clarifier).  Cost formulations for sec-
ondary clarifiers are as follows:


                            CC = 11,680X°'6523

                           OHR=
                           XHR = 301X0'60U
where

     CC = capital cost, dollars

    OHR = annual operating labor, man-hours
    XHR = annual maintenance labor, man-hours

           SA
          1000
QTT _  SA
   - -, nnn = surface area, sq ft
                                 8-8

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                                                           EM 1110-2-501

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                                                              29 Sep 78

8-10.  Filtration.  Cost formulations for filtration units are as

follows:



                           CC = 100,OOOX   519



                          OHR = 0



                          XHR = 0



                           SU = 365(U5)X°'6373



where



    CC = capital cost, dollars



     X = Q    = average flow, mgd
          avg


    SU = Q    = average flow, mgd
          avg


8-11.  Vacuum Filtration.  Cost formulations for vacuum filtration units

are as follows:




                            CC = 38l6A°'T313



                           OHR = 30.5TPY°'6U63



                           XHR = 1K15TPY0'668



                            SU=M*.5TPY°-7139+30.3TPY°-8365



where


     CC = capital cost, dollars



      A = filter area, sq ft



    OHR = annual operating labor, man-hours


          B(C)8.3M365)

            100(2000)


      B = sludge volume, gpd



      C = solids, percent




                                 8-9

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29 Sep 78
    XHR = annual maintenance labor, man-hours

     SU = materials and supply cost, dollars

8-12.  Centrifugation.  Cost formulations for centrifugation units are
as follows :


               CC = 32,92TA°'52''ri

              OHR =
               SU = 17.3B0'884 + 51.7B0'713
where
     CC = capital cost, dollars

               sludge flow (2U)
      A =
          hours per day of operation

    OHR = annual operating labor, man-hours

      B = sludge volume (% solidsj 8.3M365)
                      100(2000)

    XHR = annual maintenance labor, man-hours

     SU = materials and supply cost, dollars

      C = total horsepower required, hp

8-13-  Microscreening.  Cost formulations for microscreening units are
as follows:


                     CC = 0.031^6X°-8893(1,000,000)

                    OHR = 0

                    XHR = 0

                     su = 6.o(365)x0'96011
                                 8-10

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                                                           EM 1110-2-501
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                                                              29  Sep  78

where

    CC = capital cost, dollars

     X = Q    = average flow, mgd
          avg
    SU = materials and supply cost, dollars

8-lU.  Drying Beds.  Cost formulations for drying beds are as follows:
                             cc =

                            OHR = 17.1B°'T395

                            XHR = 2.93B0'913

                                       °'9W9
                             SU = 2.

where

     CC = capital cost, dollars

      X = SA = surface area, sq ft

    OHR = annual operating labor, man-hours

      B = TPY = tons sludge per year

    XHR = annual maintenance labor, man-hours

     SU = materials and supply costs, dollars

8-15.  Postaeration.  Cost formulations for postaeration chambers
equipped with mechanical or diffused aerators are as follows:

                        CC = 2,6l6.8x + 19,5^7.6

where

    CC = capital cost, dollars

     X = Q    = maximum flow, mgd
                                 8-11

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8-l6.  Cascade Aeration.  No cost formulations are available, at present,
for cascade aeration units.

8-17.  Sludge Hauling and Land Filling.  To be furnished.

8-l8.  Multiple Hearth Incineration.  To be furnished.

8-19.  Fluid!zed Bed Incineration.  To be furnished.
                                 3-12

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                  Section III.  CHEMICAL UNIT PROCESSES

8-20.  Carbon Adsorption.  Cost formulations for carbon adsorption units
are as follows:

                     CC = 566,856 + 8l,61*7X

                    OHR = 0

                    XHR = 1,1*UOX

                     su =
                          0.000112U5 + 0.00000014X
where

     CC = capital cost, dollars

      X = Q    = average daily flow, mgd

    XHR = annual maintenance labor, man-hours

     SU = materials and supply cost, dollars

8-21.  Chemical Coagulation.  Cost formulations for chemical coagulation
units are as follows:

                           CC = 15,028X0<1*2T

                          OHR = 0

                          XHR = 0

                           SU = 27X°'599

where

    CC = capital cost, dollars
       _    VFL     _ volume of flocculator, gal
         T.W(IOOO) =         7. ^8(1000)
    SU = materials and supply cost, dollars

See Section 8-8 for cost of clarifier coagulation unit.
                                 8-13

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8-22.  Ammonia Stripping.  Cost formulations for both crosscurrent and
counter cur rent ammonia stripping towers are as follows :
                        CC = 0.095X°'9(1,000,000)
                       OHR = 0
                       XHR = 0
                        SU = U
where
    CC = capital cost, dollar
     X = Q    = average flow, mgd
          avg
    SU = materials and supply cost, dollars
8-23.  Ghlorination.  Cost formulations for chlorine contact tanks are
as follows :
                    CC = 6917X0'611 + 3.89B°^18
                   OHR = 8
                   XHR = 7.57TPY0'801
                                              0'88
                    SU = 447TPY    '^  + 273TPY
where
     CC = capital cost, dollars
             VCT	 _ volume of contact tank, gal
      X ~ 7.48(1000) ~         7.48(1000)
      B = CR =  chlorine requirement, Ib/day
     OHR = annual operating labor, man-hours
     TPY = ^yy^- = tons per year
     XHR  =  annual maintenance labor, man-hours
      SU  =  materials  and supply  cost,  dollars

                                  8-lU

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                                                             Part 1 of 3
                                                               29 Sep 78

8-2U.   Ion Exchange.   Cost formulations for both anionic and cationic
exchange columns are as follows:

                           CC = ll*6,9H3X°'88

                          OHR = 0

                          XHR = 0
                                      0 7?
                           SU = 3,371X

where

    CC = capital cost, dollars

     X = Q    = average flow, mgd
          avg
    SU = materials and supply cost, dollars

8-25.  Neutralization.  Cost formulations for neutralization units are
as follows:

                       CC = 0.06X°-7(1,000,000)

                      OHR = 0

                      XHR = 0

                       SU = 0

where

    CC = capital cost, dollars

     X = Q    = average flow, mgd

8-26.  Recarbonation:  At present no cost data are available for re-
carbonation units.  As costs are made available they will be included
in this section.

8-27-  Two-Stage Lime Treatment.  At present, prices are available only
for the first stage of a two-stage lime treatment unit.  Cost formula-
tions for this first  stage unit are as follows:

                                 8-15

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EM 1110-2-501
Part 1 of 3
29 Sep 78

                         CC = 29U.U57 + 30.075X

                        OHR = 0

                       XHR = 2,683X°'U6

                        SU = 1,82UX°'65

where

     CC = capital cost, dollars

      X = Q    = average flow, mgd

    XHR = annual maintenance labor, man-hours

     SU = materials and supply cost, dollars
                                 8-16

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep 78
                 Section IV.  BIOLOGICAL UNIT PROCESSES
8-28.  Trickling Filters.  Cost formulations for trickling filters are
as follows:


                            CC = 5877X0'729

                           OHR = 57.9SA0'636

                           XHR = 51.3SA0'562

                            SU = 163.3SA°A65

where

     CC = capital cost, dollars
             2 0
       Y =      avg   _ 2 average flow (mgd)
           7.U8(1000) "      7-^8(1000)

    OHR = annual operating labor, man-hours

    XHR = annual maintenance labor, man-hours

     SU = materials and supply cost, dollars

     SA = surface area, sq. ft

8-29.  Plug Flow Activated Sludge.  Cost formulations for plug flow
activated sludge units are as follows:

                            CC = 5658X0'6627

                           OHR = 0

                           XHR = 0

                           SU = 0

where

    CC = capital cost, dollars

     X =     Qavg^100°) = 0.5 (average flow) 1000
              77^87.U8


                                 8-17

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Part 1 of 3
29 Sep 78

8-30.  Complete Mix Activated Sludge.  Cost formulations for complete
mix activated  sludge units are as follows:

                            CC = 5658X0'6627

                           OHR = 0

                           XHR = 0

                            SU = 0

where

    CC = capital  cost, dollars

         Qavg^1000^ _ average flow  (mgd)(lOOO)
     X~     jTW    ~           T.kB
8-31.  Step  Aeration Activated Sludge.   Cost  formulations  for  step
aeration sludge units are as follows:

                            CC = 5658X0'6627

                           OHR = 0

                           XHR = 0

                            SU = 0

where

     CC = capital  cost, dollars

         ^Wr000^ _ average flow  (mgd)lOOO
      X -     ^-£g               7.U8

 8-32.  Extended Aeration Activated  Sludge.  Cost formulations  for ex-
 tended aeration activated sludge are  as  follows:

                            CC =  5658X0'6627

                            OHR =  0

                            XHR =  0

                            SU =  0
                                  3-18

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                                                           EM 1110-2-501
                                                             Part 1 of 3

                                                              29 Sep 78
where

     CC = capital cost, dollars
        _ (l-5)Qavg(l°00) _ 1.5 average flow (mgd) 1000
      A ~      7A8       "            7-^8

8-33.  Modified or High-Rate Aeration Activated Sludge.  Cost formula-
tions for high-rate aeration activated sludge are as follows:

                            CC = 5658X0'6627

                           OHR = 0

                           XHR = 0

                            SU = 0

where

     CC = capital cost, dollars

      v - (0'2^)Qavg(l000) _ 0.25 average flow (mgd) 1000
      * ~       7.^8       ~            7.1*8

8-3^.  Contact Stabilization Activated Sludge.   Cost formulations for
contact stabilization activated sludge units are as follows:

                            CC = 5658X0'6627

                           OHR = 0

                           XHR = 0

                            SU = 0

where

     CC = capital cost, dollars
                     _ average flow (mgd) 1000
                     ~
                                 8-19

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Part 1 of 3
 29 Sep 78

8-35.  Pure Oxygen Activated Sludge.  Cost formulations for pure oxygen
activated sludge units are as follows:
                                                  •*_
                             CC = 5658X0'6627

                            OHR = 0

                            XHR = 0

                             SU = 0

where

    CC = capital cost, dollars

       _ (°-3)Qavg(l0°0) _ 0.5 average flow  (mgd) 1000
     X~      fTtS       ~            7.^8

8-36.  Aerated Aerobic Lagoons.  Cost formulations for aerated aerobic
lagoons are as follows:

                           CC = 23,222X0'6311

                          OHR = TUX0'361
                                    0 ?QQ
                          XHR = 125X   ^

                           SU = 0

where

     CC =  capital cost,  dollars

       X =  V = volume  of  lagoon, million  gal

     OHR =  annual operating labor, man-hours

     XHR =  annual maintenance labor, man-hours

 8-37.  Aerated Facultative Lagoon.  Cost formulations  for  aerated
 facultative lagoons are  as follows:

                           CC  =  23,222X°'6311

                                  8-20

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                                                           EM 1110-2-501
                                                             Part 1 of  3
                                                               29 Sep 78

                             OHR = 711X°'361
                                       0 "3QQ
                             XHR = 125X  0>y

                              SU = 0
where

     CC = capital cost, dollars

      X = V = volume of lagoon, million gal

    OHR = annual operating la"bor, man-hours

    XHR = annual maintenance labor, man-hours

8-38.  Oxidation Ditch.  Cost formulations for oxidation ditches are
as follows:

                            CC = 5658X0'6627

                           OHR = 0

                           XHR = 0

                            SU = 0

where

    CC = capital cost, dollars

                         _ 1.5 average flow (mgd) 1000
              7758

8-39.  Nitrification-Denitrif ication.   Cost formulations for
nitrification-denitrification units are as follows:

    a.  Nitrification.

                            CC = 5658X0'6627

                           OHR = 0

                           XHR = 0

                            SU = 0

                                8-21

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EM 1110-2-501
Part 1 of 3
29  Sep  78

where

     CC = capital cost, dollars

          QaYg(l°°0) _ average flow (lOQO)
      X ~    7.U8             7.U8

     b.  Denitrif icat ion.

                            cc =

                           OHR = 0

                           XHR = 0

                            SU = 0

where

     CC = capital cost, dollars

                     _ average flow  (mgd)  1000
      X "
             7.1*8    "
      c.  Mechanical  aeration.


                           CC =  2911A0'788
                                    A liQ
                          OHR =  150A   y

                          XHR=
 where

       CC = capital cost,  dollars

      OHR = annual operating labor,  man-hours
 1  Mechanical or diffused aeration is used with processes described in
   paragraphs 8-30 through 8-HO.

                                   8-22

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                                                            EM 1110-2-501
                                                              Part  1  of 3
                                                               29 Sep 78

     XHR = annual maintenence  labor, man-hours

      SU = materials  and  supply cost,  dollars

      A = hp  = horsepower required

     d.   Diffused Aeration.

                            CC =  78230X0'6627

                           OHR =  937X°-Wl8

                           XHR =  i,63X°- ^6l

                            SU =  0

where

     CC  = capital cost, dollars

      X  = required air flow, 1000 cfm

     OHR  = annual operating labor, man-hours

     XHR  = annual maintenance labor, man-hours

8-40.  Aerobic Digestion.  Cost formulations for aerobic digesters are
as follows:

                            CC = 5658X0'6627

                           OHR = 0

                           XHR = 0

                            SU = 0

where

    CC =  capital cost, dollars



   Mechanical or diffused aeration is  used with processes described
  in paragraphs  8-30 through 8-kO.

                                 8-23

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EM 1110-2-501
Part 1 of 3
 29 §ep 78

       _    vol     _ volume (million gal)
       ~ 7.1*8(1000) ~    7.^8(1000)

8-1*1.  Anaerobic Digestion.  Cost formulations for anaerobic digesters
are as follows:

                            CC = 17,1*32X°'5TT3

                           OHR = 88.8X0'6132

                           XHR = 56.7X0'596

                            su = i9ix°-6058


where

     CC = capital cost, dollars
        _ vol  _ volume (million gal)
        ~ 1000 "        1000
    OHR = annual operating labor, man-hours

    XHR = annual maintenance labor, man-hours

     SU = materials and supply costs,  dollars

8-1*2.  Stabilization  Ponds.  Cost formulations  for  stabilization ponds
are as follows:

                           CC =  20,180X°-58314

                           OHR =  58X°'55T

                                     ° "
                           XHR  =  10UX

                            SU-1U2X0'513

 where

      CC = capital cost,  dollars

       X = SA = surface area,  sq  ft

     OHR = annual operation labor, man-hours


                                 8-2H

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                                                      EM 1110-2-501
                                                        Part 1 of 3
                                                         29 Sep 78
XHR = annual maintenance labor, man-hours

 SU = materials and supply costs,  dollars
                             8-25

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                                                           EM 1110-2-501
                                                             Part 1 of 3

                                                               29 Sep  78
                               APPENDIX A

                               REFERENCES

ATbertson, 0. E. and Guidi, E. E., Jr., "Centrifugation of Waste
Sludges," Journal, Water Pollution Control Federation, Vol 1*1, Apr 1969,
pp 607-628.

ATbertsson, T. G. et al., "Investigation of the Use of High Purity
Oxygen Aeration in the Conventional Activated Sludge Process," Water
Pollution Control Research Series Report No. 17050DNW, May 1970, Federal
Water Quality Administration, Washington, D. C.

Alford, J. M., "Sludge Disposal Experiences at North Little Rock,
Arkansas," Journal, Water Pollution Control Federation, Vol 1*1, No. 1,
pp 175-183.

American Public Health Association, American Society of Civil Engineers,
American Water Works Association, and Water Pollution Control Federa-
tion, "Glossary, Water and Wastewater Control Engineering," 1969.

American Public Works Association, "Feasibility of Computer Control of
Wastewater Treatment," Report No. 17090DOY, Dec 1970, U. G, Environ-
mental Protection Agency, Washington, D. C.

American Society of Civil Engineers and the Water Pollution Control
Federation, "Sewage Treatment Plant Design," Manual of Practice No. 8,
1959, 1961, 1967, 1968, Water Pollution Control Federation, Washington,
D. C.

American Water Works Association, Water Quality and Treatment, McGraw-
Hill, New York, 1971.

Amirtharajah, A. and Cleasby, J. L., "Predicting Expansion of Filters
During Backwash," Journal, American Water Works Association, Vol 61*,
1972, pp 52-59-

Anderson, C. V., "Zero Discharge Sanitation System," 53rd Annual Wash-
ington Association of State Highway Officials Conference, 6 Jun 197^»
Portland, Oreg.

Baker, J. M. and Graves, Q. B., "Recent Approaches for Trickling Filter
Design," Journal, Sanitary Engineering Division, American Society of
Civil Engineers, Vol 9^, SA1, Feb 1968, pp 65-81*.


                                  A-l

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EM 1110-2-501
Part 1 of 3
29 Sep 78

Balakrishnan, S., Williamson, D., and Odey, R., "State of the Art
Review on Sludge Incinerator Practices," Report No. 17070 Div 0^/70,
Apr 1970, Federal Water Quality Administration, Washington, D. C.

Bargman, R. D. and Borgerding, J., "Characterization of the Activated
Sludge Process," Report No. R2-73-22U, Apr 1973, U. S. Environmental
Protection Agency, Washington, D. C.

Barnard, J. L. and Eckenfelder, W. W., Jr., "Treatment-Cost Relation-
ships for Organic Industrial Wastes," 5th International Water Pollution
Research Conference, Jul-Aug 1970.

Barnard, J. L. and Eckenfelder, W. W., Jr., "Treatment-Cost Relation-
ships for Industrial Waste Treatment," Technical Report No. 23,  1971,
Environmental and Water Resources Engineering, Vanderbilt University,
Nashville, Term.

Barnhart, E. L.  and Eckenfelder, W. W., Jr.,  "Theoretical Aspects of
Aerated Lagoon Design," Symposium on  Wastewater Treatment for Small
Municipalities,  1965, Ecole Polytechnique, Montreal,  Quebec, Canada.

Barsom, G.,  "Lagoon Performance and the State of Lagoon Technology,"
Report No. R2-73-1M, Jun  1973, U. S. Environmental Protection Agency,
Washington,  D. C.

Bennett,  E.  R.,  Rein, D. A.,  and Linstedt, K. D.,  "Economic Aspects of
Sludge Dewatering and Disposal," Journal  of Environmental  Division^
American  Society of Civil  Engineers,,,  Vol  99 >  1973, P  55-

Bernard,  J.,  "Sludge  Centrifugation," 1st Seminar  on  Process  Design for
Water Quality Control,  1970,  Vanderbilt University, Nashville,  Tenn.

 Bishop,  N.  E., Malina,  J.  F., Jr.,  and  Eckenfelder, W.  W.,  Jr.,  "Studies
 on Mixing and Heat  Exchange in Aerated  Lagoons,"  Technical Report
 EHE-70-21,  CRWR-70, 1970,  Center for  Research in  Water  Resources,
 University of Texas at  Austin.

 Blecker,  H.  G.  and Cadman, T. W.,  "Capital and Operating Costs of
 Pollution Control Equipment Modules - Vol I," Report  No.  R5-73-023a,
 Jul 1973, U. S.  Environmental Protection Agency,  Washington,  D.  C.

 Blecker, H.  G.  and Nichols, T. M., "Capital and Operating Costs of
 Pollution Control Equipment Modules - Vol II," Report No.  R5-73-023t>,
 Jul 1973, U. S.  Environmental Protection Agency,  Washington,  D. C.


                                   A-2

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                               29 Sep  78

Borchardt, J. A., "Nitrification in the Activated Sludge Process,"
The Activated Sludge Process, Bulletin, University of Michigan, Ann
Arbor, Mich.

Bordien, D. G. and Stenburg, R. L. , "Microscreening Effectively Polishes
Activated Sludge Effluent," Water and Wastes Engineering, Vol 3,
Sep 1966, pp 7^-77.

Boucher, P. L. , "A New Measure of the Filtrability of Fluids with Appli-
cation to Water Engineering," ICE Journal (British), Vol 27, No. U,
19^7, PP
Bouwer, H. , "High Rate Land Treatment," Water Spectrum, Vol 6,  No.  1,
    , PP 18-25.
Bowers, M. , "Tips on Sludge Drying Beds Care," Sewage and Industrial
Waters, Vol 29, No. 7, Jul 1957, PP 835-836.

Brown and Caldwell, Engineers for EPA, "Nitrification and Denitrification
Facilities," May 7-9, 197^, U. S. Environmental Protection Agency Tech-
nology Transfer, Orlando, Fla.

Brown, J. C. et al., "Methods for Improvement of Trickling Filter Plant
Performance - Part I, Mechanical and Biological Optima," Report No.  670/
2-73-OH7a, Aug 1973, U. S. Environmental Protection Agency, Washington,
D. C.

Burd, R. S., "A Study of Sludge Handling and Disposal," Publication
WP-20-1+, May 1968, Federal Water Pollution Control Administration, Wash-
ington, D. C.

Burgess, J. V., "Comparison of Sludge Incineration Processes," Process
Biochemistry, Vol 3, Apr 1968, p 27.

Burkhead, C. E. , "Evaluation of CMAS Design Constants," Conference on
Toward a Unified Concept of Biological Waste Treatment Design, 5-6 Oct
1972, Atlanta, Ga.

Burkhead, C. E. and McKinney, R. E., "Application of Complete-Mixing
Activated Sludge Design Equations to Industrial Wastes," Journal, Water
Pollution Control Federation, Vol kO, Apr 1968, pp 557-570.
                                 A-3

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EM 1110-2-501
Part 1 of 3
29 Sep 78

Burns and Roe, Inc., "Process Design Manual for Suspended Solids
Removal," prepared for the U. S.  Environmental Protection Agency Tech-
nology, Transfer, Oct 1971, Washington, D. C.

Busch, A. ¥., Aerobic Biological Treatment of Wastewaters, Oligodynamics
Press, 1971-

Camp, T. R., "Grit Chamber Design," Sewage Works Journal, Vol 1^, No.  2,
Mar 19^2, pp 368-381.

Camp, T. R., "Sedimentation and the Design of Settling Tanks," Transac-
tions, American Society of Civil Engineers, Vol 111, Part III, 19^6",
pp 895-952.

Camp, T. R., "Flocculation and Flocculation Basins," Transactions,
American Society of Civil Engineers, Yol 120, 1955, PP l-l6.

Camp, T. R., "Theory of Water Filtration," Journal, Sanitary Engineer-
ing Division, American Society of Civil Engineers, Vol 90, SAH, 196U,
pp 1-30.

Cardile, R.  P. and Verhoff, F. H., "Economical Refuse Truck Size
Determination," Journal, Environmental Engineering Division, American
Society of  Civil Engineers, Vol 90, SAU, 196^, pp 1-30.

Cardinal, P. J., "Advances in Multihearth Incineration," Process Bio-
chemistry,  Vol 6, 1971, PP 27-31.

Carlson, C.  A., Hunt, P. G., and Delaney, T. B., Jr., "Overland Flow
Treatment  of Wastewater," Miscellaneous Paper Y-TU-3, Aug 197^, U.  S.
Army  Engineer Waterways Experiment Station, CE, Vicksburg, Miss.

Center  for  Research,  Inc., University  of  Kansas, "Oxygen  Consumption  in
Continuous  Biological Culture," Report Number 17050DJS, May 1971, U.  S.
Environmental Protection Agency, Washington, D. C.

Center  for  the Study of Federalism,  "Green  Land -  Clean  Streams:  The
Beneficial Use of Wastewater Through Land Treatment," 1972, Center  for
the  Study  of Federalism, Temple University, Philadelphia, Pa.

City of Austin,  Texas,  "Design Guides  for Biological Wastewater  Treat-
ment Processes," Report No.  11010ESQ,  Aug 1971, U.  S. Environmental
Protection Agency,  Washington, D.  C.
                                  A-U

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                                                            EM 1110-2-501
                                                              Part 1 of 3

                                                               29 Sep 78

 Clark, B.  D. ,  "Basic Characteristics at Winter Recreational Areas."
 PR-T, Aug  1968,  Federal Water Quality Administration,  Washington, D.  C.

 Clark, J.  W. and Viessman,  W. , Jr.,  Water Supply and Pollution Control.
 International  Textbook Co., Scranton,  1966.

 Clark, R.  M. and Gillean, J.  I.,  "Systems Analysis  and Solid Waste
 Planning," Journal.,  Environmental Engineering  Division,  American
 Society of Civil Engineers^ Vol 100,  1974, p 7.

 Clark, R.  M. and Helms,  B.  P., "Fleet  Selection for Solid Waste  Collec-
 tion Systems," Journal,  Environmental  Engineering Divisip]n.J,__Ameri£an
 Society of Civil Engineers,  Vol 98,  1972,  p 71.

 Cleasby, J. L. ,  "Deep  Granular Filters,  Modeling and Simulation,"  Pro-
 ceeding, Association of  Environmental  Engineers  in  Profession, Eighth
 Annual Workshop,  18-22 Dec  1972,  Nassau.

 Cleasby, J. L. and Baumann,  E.  R., "Selection  of Sand  Filtration  Rates,"
 Journal, American Waterworks  Association, Vol  $k, 1962, pp  579-602.

 Cohen,  J.  M. and  Hannah, S. A., "Coagulation and Flocculation," Water
 Quality and Treatment^ McGraw-Hill, New  York,  1971.

 College of Engineering,  Oklahoma  State University,  "Aerobic Digestion
 of Organic Wastes," Report No.  17070DAU, Dec 1971, U. S. Environmental
 Protection Agency, Washington,  D.  C.

 Copeland,  C. G. ,  "Water  Reuse  and Black Liquor Oxidation by the Container -
 Copeland Process," Proceedings, 19th Industrial Waste Conference, Purdue
University, Lafayette, Ind.  , 1969.

Copeland,  C. G. , "The Copeland Process Fluid Bed System and Pollution
Control Worldwide," Proceedings, 2Uth Industrial Waste Conference.
Perdue University, Lafayette, Ind., 1969.

Copeland, C. G. , "Design and Operation of Fluidized Bed Incinerators,"
Water and Sewage Works, Vol  117, 1970, p
Cotteral, J. A., Jr., and Norris, D. P., "Septic Tank Systems," Journal .
Sanitary Engineering Division, American Society of Civil Engineers
Vol 95, SA4,"l969, pp 715-746.                                    *"
                                 A-5

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EM 1110-2-501
Part 1 of 3
29 Sep 78

Cover, A. E. and Pieron, L.  J. , "Appraisal of Granular Carbon Contactors
Phase I and II," Report No.  TWRC-11, May 1969, Federal Water Pollution
Control Administration, Washington, D.  C.

Cover, A. E. and Wood, C. E. , "Appraisal of Granular Carbon Contactors
Phase III," Report No. TWRC-12, May 1969, Federal Water Pollution Con-
trol Administration, Washington, D. C.

Gulp, G. L., Hsuing, K. , and Conley, W. R., "Tube Clarification Process,
Operation Experience," Journal, Sanitary Engineering Division, American
Society of Civil Engineers, Vol 95, SA5, 19o9, PP 829-8U8.

Gulp, R. L. and Gulp, G. L. , Advanced Wastewater Treatment, Van Nostrand,
New York, 1971.

Daniels, S. L. , "Phosphorus Removal from Wastewater by Chemical Precip-
itation and Flocculation," The American Oil Chemists' Society, 1971,
Short Course, Update on Detergents and Raw Materials, Jun 1971, Lake
Placid, N. Y.

"Design and Operation of Complete Mixing Activated Sludge Systems,"
Environmental Pollution Control Service Reports, Vol 1, No. 3, Jul 1970.

Dick, R. I., "Fundamental Aspects of Sedimentation 2," Water and Wastes
Engineering, Vol  6, No.  3,  1969, PP ^-^5.

Dick, R. I., "Thickening,"  Advances in Water  Quality Improvements -
Physical and Chemical Processes,, E. F. Gloyna and W. W. Eckenf elder, Jr.,
ed. ,  University of  Texas Press, Austin,  1970.

Dick, R. I., "Thickening,"  Seminar  on Process Design  in Water Quality
Engineering, 9-13 Nov  1970,  Vanderbilt University, Nashville, Tenn.

Dick, R. I., "Sludge  Treatment, Disposal,  and Utilization Literature
Review," Journal, Water Pollution  Control  Federation, Vol 1*3, Jun 1971,
pp           "
 Door-Oliver,  Incorporated,  "Cost  of Wastewater  Treatment Processes,"
 Report No.  TWRC-6,  Dec 1968,  Federal Water  Pollution Control Administra-
 tion, Cincinnati, Ohio.

 Dow Chemical Company,  "A Literature Search  and  Critical Analysis  of Bio-
 logical Trickling Filter Studies  - Vols I and II,"  Report  No.  17050-DDY,
 Dec 1971, U.  S. Environmental Protection Agency,  Washington, D. C.

                                  A-6

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                                                            EM 1110-2-501
                                                              Part 1 of 3

                                                               29 Sep 78
 Drier, D. E. , "Aerobic Digestion of Solids," Proceedings of l8th Purdue
 Industrial Waste Conference, 1963, Purdue University, Lafayette, Ind.

 Drier, D. E.,  "Aerobic Digestion of Sludge," paper presented at  Sanitary
 Engineering Institute, Mar 1965, University of Wisconsin,  Madison,  Wis.

 Ducar, G. J. and Levin, P.,  "Mathematical Model of Sewage  Sludge Fluid-
 ized Bed Incinerator Capacities  and Costs," Report No.  TWRC-10,  1969,
 Federal Water  Quality Control Administration,  Washington,  D.  C.

 Eckenfelder, W.  W.,  Jr.,  "Trickling Filter Design  and Performance,"
 Transactions,  American Society of Civil  Engineers,  Vol  128,  Part III,
 1963,  pp 371-39^.

 Eckenfelder, W.  W.,  Jr.,  Industrial Water Pollution  Control,  McGraw-
 Hill,  New York,  1966.

 Eckenfelder, W.  W. ,  Jr.,  "Aerated Lagoon," Manual  of Treatment Processes^
 Vol  I,  1969, Environmental Science Services,  Inc.,  Briarcliff Manor New
 York.

 Eckenfelder, W.  W.,  Jr.,  "General Concepts of  Biological Treatment,"
 Manual of Treatment  Processes, Vol 1, 1969,  Environmental  Science
 Services,  Inc.,  Briarcliff Manor,  New York.

 Eckenfelder, W.  W.,  Jr., Water Quality Engineering  for Practicing
 Engineers, Barnes and  Nobel,  New York, 1970.

 Eckenfelder, W.  W.,  Jr., "Activated  Sludge and Extended Aeration,"
 Process Design in Water Quality Engineering - JJew Concepts and Develop-
ments , 1971, Vanderbilt University, Nashville, Tenn.

 Eckenfelder, W. W.,  Jr., and  Earnhardt, W.,  "Performance of a High-Rate
 Trickling Filter Using Selected Media," Journal, Water Pollution Control
 Federation, Vol  35,  No. 12, 1963, pp 1535-1551.

Eckenfelder, W. W., Jr., and  Cecil, L. K., Application of New Concepts
of Physical-Chemical Wastewater Treatment, Pergamon P^-ess  New York
1972.

Eckenfelder, W. W., Jr., and Ford, D. L.,  "Economics of Wastewater
Treatment," Chemical Engineering^ Vol 76, Aug 1969, pp 109-118.

Eckenfelder, W. W., Jr., and Ford, D. L., Water Pollution Control.
Pemberton Press, New York, 1970.

                                  A-7

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Eckenfelder, W. W.,  Jr., and O'Connor, 0. J., Biological Waste Treatment,
Pergamon Press, New York, 1961.

Edde, H. J, and Eckenfelder, W. W., Jr., "Theoretical Concept of Gravity
Sludge Thickening," Technical Report EHE-02-6701, CRWR-15, 1967, Center
for Research in Water Resources, University of Texas, Austin.

Eilers, R. G. and Smith, R., "Wastewater Treatment Plant Cost Estimating
Program," Apr 1971,  Environmental Protection Agency, Water Quality
Office, Advanced Waste Treatment Research Laboratory, Cincinnati, Ohio.

Engineering-Science, Inc., "State of the Art of the Microscreen Process,"
prepared for the Federal Water Quality Administration, Contract No. ik-
12-819, Jul 1970, Washington, D. C.

Engineering-Science, Inc., "Theoretical Formulation of Operational Model
for Simulation of Microscreen Behavior, Report No. B-l, Sep 1970, Federal
Water Quality Administration, Washington, D. C.

Engineering-Science, Inc., "Current State of Operational Model  for Simu-
lation of Microscreen Behavior," prepared for the Federal Water Quality
Administration, Contract No. ]A-12-8l9, Nov 1970, Washington, D. C,

Engineering-Science, Inc., "Development of Field Data Acquisition Pro-
gram for Pilot-Scale Microscreens," prepared for the Federal Water Qual-
ity Administration, Contract No. 1^-12-819, Jan 1971, Washington, D. C.

Engineering-Science, Inc., "Investigation of Response Surfaces  of the
Microscreen Process," Report No. 17090EEM, Dec 1971, U. S. Environmental
Protection Agency, Washington, D.  C.

Equipment Manufacturers' Catalogs.

Fair,  G. M. and Geyer,  J.  C.,  Elements  of Water Supply and Waste Water
Disposal., Wiley,  New York, 1955-

Fair,  G, M. and Moore,  E.  W.,  "Sewage Sludge Fuel Value Related to
Volatile Matter," Engineering  News-Record, Vol 68l,  1935-

Fair,  G. M.,  Geyer, J.  C., and Okun,  D.  A., Water Purification  and Waste-
water  Treatment and Disposal;  Water and Wastewater  Engineering^ Vol 2,
Wiley,  New York,  1968.
                                  A-8

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                                                            EM 1110-2-501
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                                                               29 Sep 78
 Field,  W.  B.,  "Design of  a  pH Control  System by Analog  Simulation,"
 Instrument Society  of American Journal, Vol  6, 1959, PP ^2-50.

 FMC  Corporation,  "Link-Belt Wastewater Treatment  Equipment  Design  Cata-
 logue,"  Binder 2650,  CoLnar,  Pa.

 Gaillard,  J. R.,  "Fluidized Bed Incineration of Sewage  Sludge," Water
 Pollution  Control,  Vol 73,  1973, pp 190-192.

 Galler,  ¥.  S,  and Gotaas, H.  B., "Analysis of Biological Filter Vari-
 ables,"  Journal,  Sanitary Engineering  Division, American Society of
 Civil Engineers?_  Vol  90,  SA6,  1.96k, pp 59-79.

 Gaudy, A.  G.,  Jr.,  and Gaudy,  E. T., "Biological  Concepts for Design
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 Germain, J., "Economic  Treatment of Domestic  Waste by Plastic-Medium
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 Gloyna,  E.  F.,  "Basis  for Waste Stabilization Pond Design," Advance^
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 Austin,  1970.

 Gloyna, E.  F.,  "Waste Stabilization Ponds," World Health Organization,
 Geneva,  Switzerland, 1971.

 Goldstein,  S. N. and Moberg, W. J., Jr.,  "Wastewater Treatment Systems
 for Rural  Communities," Commission on Rural Water, 1975.

 Goodman, B. L.  , Design Handbook of Wastewater Systems:   Domestic,
 Industrial, Commercial, Technomic,  Westport,  Conn., 1971.

 Goodman, B. L.  and Englande, A. J., Jr.,  "A Consolidated Approach to
Activated Sludge Process Design,"  Conference  on Toward a Unified Con-
 cept of Biological Waste Treatment  Design,  5-6 Oct 1972, Atlanta,  Ga.

 Gray, D. H. and Penessis,  C.,  "Engineering  Properties of Sludge Ash,"
Journal, Water Pollution Control Federation,  Vol  kk,  May 1972, p
                                 A-9

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EM 1110-2-501
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  29  Sep  78

Great Lakes-Upper Mississippi River Board of State Sanitary Engineers,
"Recommended Standards for Sewage Works (Ten States Standards)," 1971,
Health Education Service, Albany, N. Y.

Greer, W. N. , The Measurement and Control of pH, Leeds and Northrup,
Philadelphia, 1966.

Guarino, C. F. et al., "Land and Sea Solids Management Alternatives
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1975, P 2551.

Guillaume, F. P., "Evaluation of the Oxidation Ditch as a Means of
Wastewater Treatment in Ontario," Research Publication No. 6, Jul 196k,
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Hansen, S. P., Gulp, G. L. , and Stukenberg, J.  R. , "Practical Applica-
tion of Idealized Sedimentation Theory in Wastewater Treatment," Journal ,
Water Pollution Control Federation, Vol Hi, Aug 1969, pp
Hanway, J. E. , "Fluidi zed-Bed Processes - A Solution for Industrial
Waste Problems," Proceedings, 21st Industrial Waste Conference,  Purdue
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Harkness, N. et al. , "Some Observations on the Incineration of Sewage
Sludge," Water Pollution Control, Vol 71, No. 1, 1972,  pp 16-33.

Headquarters, Department of the Army and Department of  the Air Force,
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Helmenstein, S., and Martin, F., "Planning Criteria for Refuse Incinera-
tion Systems," Combustion, Vol ^5, May 197^, p 11.

Herman, E. R. and Gloyna, E. F., "Waste Stabilization Ponds,  III,  Formu-
lation of Design Equations," Sewage and Industrial Wastes, Vol 30, No. 8,
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Hinsely, T. D. , "Sludge Recycling:  The Most Reasonable Choice?" Water
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Hinsely, T. D., "Water Renovation for Unrestricted Re-Use," Water
Spectrum, Vol 5, No. 2,  1973, pp 1-8.
                                A-10

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                                                           EM 1110-2-501
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                                                               29 Sep 78
Hoak, R. D., "Acid Iron Wastes Neutralization," Sewage and Industrial
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Hoeppel, R. E. , Hunt, P. G., and Delaney, T. B., Jr., "Waste-water Treat-
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Hsuing, K. and Cleasby, J. L., "Prediction of Filter Performance,"
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Hunt, P. G., "Overland Flow," Water Spectrum, Vol 5, No. k, 1973,
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Iowa State University, "Estimating Staffing and Cost Factors for Small
Wastewater Treatment Plants Less Than 1 MGD, Parts I and II," Jun 1973,
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Jaworski, N., Lawton, G. W., and Rohlich, G. A., "Aerobic Sludge Diges-
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Jenks, J. H., "Continuous Centrifuge Used to Dewater Variety of Sludges,"
Waste Engineering, Jul 1958, pp 360-361.

Johnson, E. L., Beeghly, J. H., and Wukasch, R. F., "Phosphorus Removal
with Iron and Polyelectrolytes," Public Works, Vol 100, No. 11, 1969,
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Jones, B. R. S., "Vacuum Sludge Filtration, II, Prediction of Filter
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Kunin, R., Ion Exchange Resins, 2d ed., Wiley, New York, 1958.

Lakeside Engineering Corporation, "Rotor Aeration," Apr I960.

Lawrence, A. W. and McCarty, P. L., "Unified Basis for Biological Treat-
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Liao, P. B., "Fluidized-Bed Sludge Incinerator Design," Journal, Water
Pollution Control Federation., Vol U6, No. 8, 1972, pp 1895-1913.
                                 A-11

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Liao, P.  B. and Pilat, M. J., "Air Pollutant Emissions from Fluidized Bed
Sewage Sludge Incinerators," Water and Sewage Works , Vol 119, No. 2,
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Liptak, B. G. , Env^onmen^l_EngJ.iie_ej
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                                                           EM 1110.-2-5 01
                                                             Part 1 of 3
                                                              29 Sep 78

Marske, D. M. and Boyle, J. D., "Chlorine Contact Chamber Design - A
Field Evaluation," Water and Sewage Works, Vol 120, Jan 1973, pp 70-77.

Matherly, J., "Water Usage Rates and Wastewater Characteristics at a
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McCarty, P. L., "Biological Processes for Nitrogen Removal:  Theory and
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McCarty, P. L. and Brodersen, C. F. , "Theory of Extended Aeration Acti-
vated Sludge," Journal, Water Pollution Control Federation, Vol 3k, 1962,
pp 1095-1103.                   '            "            ~~

McKinney, R. E., "Mathematics of Complete-Mixing Activated Sludge,"
Journal, Sanitary Engineering Division., American .Soc_iety_ of_Civil_ Engi-
neers, SA3, May 1962, pp 87-113.                    ~~   "              ~

McKinney, R. E., Microbiology for Sanitary Engineers? McGraw-Hill, New
York, 1962.

McKinney, R. E., "Overloaded Oxidation Ponds - Two Case Studies,"
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McKinney, R. E., "Design and Operation of Complete Mixing Activated
Sludge Systems," Environmental Pollution Control Services Reports,
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McKinney, R. E.  and Benjes, H. H., "Design and Operation of Aerated
Lagoons," Paper No. 3P2-1, Jul 1965, National Symposium on Sanitary
Engineering Researah, Development and Design.

McKinney, R. E.  ana O'Brien, W. J., "Activated Sludge - Basic Design
Concepts," Journal, Water Pollution Control Federation, Vol 1*0,  Wov 1968,
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McKinney, R. E.  and Ooter, R. J.,  "Concepts of Complete Mixing Activated
Sludge," Bulletin No. 60, 1969, Transactions of the 19th Annual Confer-
ence on Sanitary Engineering, University of Kansas, Lawrence, Kans.

McKinney, R. E.  and Pfeffer, J. T., "Oxygen-Enriched Air for Biological
Waste Treatment," Water and Sewage Works., Vol 112,  Oct 1965, pp 381-38U.
                                 A-13

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McLaughlin, R. T., "The Settling Properties of Suspensions," Journal,
Hydraulic Division, American Society of Civil Engineers,  Part I,  Paper
No. 2311, Vol 85, No. HY12, 1959, pp 9-^1.

Mechalas, B. J., Allen, P. M.,  III, and Matyskiela,  W.  ¥.,  "A Study of
Nitrification and Denitrification," Report  No. 1T010DRD,  Jul 1970,  U.  S.
Environmental Protection Agency, Washington, D. C.

Metcalf and Eddy, Inc., Wastewater Engineering; Collection, Treatment,
and Disposal, McGraw-Hill, New York, 1972.

Middleton, E., "Basic Sewage Characteristics at a Corps of Engineers
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Millward, R. S. and Booth, P. B., "Incorporating Sludge Combustion
Into Sewage Treatment Plant," Water and Sewage Works, Vol 115, 1968,
pp R-169-171*.

Mine Safety Appliances Research Corporation, "Optimization of the Re-
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Mixon, F. 0., "Filterability Index and Microscreener Design," Journal,
Water Pollution Control Federation, Vol U2, No. 11,  Nov 1970, pp 19^-
1950.

Moore, S. F.  and Schroeder, E.  D., "An Investigation of the Effects of
Residence Time on Anaerobic Bacterial Denitrification," Water Research,
Vol k, No. 10, 1970, pp 685-69^.

Mulbarger, M. C., "Nitrification and Denitrification ia Activated
Sludge Systems," Journal, Water Pollution Control Federation, Vol ^3,
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National Research Council,  "Trickling Filters  (in Sewage Treatment at
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Neighbor, J.  B.  and  Cooper,  T. W.,  "Design  and  Operation Criteria for
Aerated  Grit  Chambers," Water and  Sewage Works, Vol 112, Dec  1965,
pp

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                                                           EM 1110-2-501
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                                                               29 Sep 78

Nemerow, N. L. , Liquid Waste of Industry, Addi son- Wesley, Reading, Mass.,
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Nesbitt, J. B. , "Removal of Phosphorus from Municipal Sewage Plant Ef-
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Okun, D. A., "System of Bio-Precipitation of Organic -Matter from Sewage,"
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O'Melia, C. R. and Stumm, W. , "Theory of Water Filtration," Journal ,
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i.'swald, W. J. , "Quality Management by Engineered Ponds," Engineering
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Parker, H. W. , "Water Supply and Waste Disposal Series, Oxidation Ditch
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Parkhurst, J. D.  et'al., "Dewatering Digested Primary Sludge,"  Journal ,
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Patterson, W. L.  and Banker, R.  F. , "Estimating Costs and Manpower Re-
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Pavoni, J. L. et al., Handbook of Solid Waste Disposal, Van Nostrand
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                                 A-15

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Peak, R.  and David, M., "Costs of Cation Exchange Equipment," Chemical
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Pohland,  F. G. and Kang, J. J., "Anaerobic Processes,"  Journal, Water
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Prather,  B. F. , "Waste-water Aeration," The Oil and Gas  Journal, Vol 57,
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Reed, S.  C. and Buzzell, T. D., "Land Treatment of Wastewaters for Rural
Communities," Rural Environmental Engineering Conference, 26-28 Sep 1973,
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Rex Chainbelt, Inc., "A Mathematical Model of a Final Clarifier," Re-
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Reynolds, E., Gibbon, J. D., and Atwood, D., "Smoothing Quality Vari-
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Rodriguez, R. T., "Aqua-Sans Sewage Disposal System," Special Training
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Roesler, J. F.,  Smith, R.,  and Eilers, R. G., "Mathematical Simulation
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Roy F. Weston.,  Inc., "Process Design Manual for Upgrading Existing
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Ruben, A. J.,  "Chemistry of Water Supply Treatment and Distribution,"
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Sanks, R. L.,  "Ion  Exchange," Seminar  on Process  Design  for Water
Quality Control,  9-13 Nov  1970, Vanderbilt  University, Nashville, Tenn.
                                 A-16

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                                                           EM 1110-2-501
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Sawyer, C. N., "New Concepts in Aerated Lagoon Design and Operation,"
Advances in Water Quality Improvements - Physical and Chemical
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Sawyer, C. N., "Nitrification and Denitrification Facilities," Aug 1973,
U. S. Environmental Protection Agency, Technology Transfer, Washington,
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Sawyer, C. N. and Grubling, J.  S., "Fundamental Considerations in High
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Sawyer, C. N. and McCarty, P. L., Chemistry for Sanitary Engineers,
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Schuessler, R. G., "Phosphorus Removal - A Controllable Process,"
Chemical Engineering Progress Symposium Series, Vol 67,  No. 107, 1971-

Schulze, K. L., "Load and Efficiency of Trickling Filters," Journala
Water Pollution Control Federation, Vol 32, Wo. 3, I960,  pp 245-261.

Searle, S. S. and Kirby, C. F., "Waste into Wealth," Wate_r Spectrum,
Vol k, No. 3, 1972, pp 15-21.

Seedel, D. F. and Criter, R. W., "Evaluation of Anaerobic Denitrifica-
tion Processes," Journal, Sanitary Engineering Division,  American
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Shea, T. G. and Stockton, J. D., "Wastewater Sludge Utilisation and
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Shindala, A, and Bryme, W. J., "Anaerobic Digestion of Thickened Sludge,"
Public Works, Vol 101, Feb 1970, pp 73-76.

Shindala, A., Dust, J. V., and Champion, A. L., "Accelerated Digestion
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Shinskey, F. G., "Feed Forward Control of pH," Instrumentation Tech-
nology, Vol 15, 1968.
                                A-17

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Simpson, G. D., "Operation of Vacuum Filters," Journal, Water Pollution
Control Federation, Vol 36, Dec 1961*, pp ll*60-J*67.

Slechta, A. F. and Culp, G. L. , "Water Reclamation Studies at the South
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"Sludge Incineration Plant Uses Fluid-Bed Furnace," Chemical and Process
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Smith, H.  S., "Homogeneous Activated Sludge/1 Principles and Features
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Smith, R. , "Cost of Conventional and Advanced Treatment of Waste Water,"
Journal, Water Pollution Control Federation, Vol 1*0, Sep 1968, pp 15^*6-
__
Smith, R. , "Preliminary Design of Wastewater Treatment Systems," Journal ,
Sanitary Engineering Division, American Society of Civil Engineers,
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Smith, R. , "Design of Ammonia Stripping Towers for Wastewater Treat-
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Smith, R. and Eilers, R. G. , "A Generalized Computer Model for Steady-
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Smith R. and McMlchael, N. R. , "Cost of Wastewater Treatment Processes,"
FWPCA Report No. TWRC-6, Dec 1968, Robert A. Taft Water Research Center,
Cincinnati, Ohio.

Smith, R. and McMichael, W. F. , "Cost and Performance Estimates for
Tertiary Wastewater Treating Processes," PB 189 953, Jun 1969, Federal
Water Pollution Control Administration, Cincinnati, Ohio.

Snoeyink, V. L. a,nd Mahoney, J. A., "Summary of Commercially Available
Wastewater Treatment Plants," Technical Report No. AFWL-TR-72-l*5, Jul
1972, Air Force Weapons Laboratory, Kirtland Air Force Base, Albuquerque,
N . Mex .
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                                                           EM 1110-2-501
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Snow, R. H. and ¥enk, W. J., "Ammonia Stripping Mathematical Model for
Wastewater Treatment," Report No. IITRI-C6152-6, Dec 1968, Federal Water
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South Tahoe Public Utility District, "Advanced Wastewater Treatment as
Practiced at South Tahoe," Report No. 1T010ELQ, Aug 1971, U. S. Envi-
ronmental Protection Agency, Washington, D. C.

Stander, G. J. and Van Vuuren, L. R. J., "Flotation of Sewage and Waste
Solids," Advances in Water Quality Improvements - Physical and Chemical
Processes, E. F. Gloyna and W. W. Eckenfelder, Jr.,  ed., University of
Texas Press, Austin, 1970.

Stanley Consultants, Inc., "Sludge Handling and Disposal, Phase I, State
of the Art, Report to Metropolitan Sewer Board of the Twin Cities Area,"
Nov 15, 1972.

Stanley Consultants, Inc., "Wastewater Treatment Unit Processes Design
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Stensel, H. D. and Shell, G. L., "Two Methods of Biological Treatment
Design," Journal, Water Pollution Control Federation, Vol 1*6, Feb 197**,
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Stewart, M. J. , "Activated Sludge System Variations - Specific Applica-
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Stumm, W. and Morgan, J. J., Aquatic Chemistry, Wiley, New York, 1970.

Stumm, W. and O'Melia, C. R., "Stoichiometry of Coagulation," Journal,
American Water Works Association, Vol 60, 1968, pp 51^-539-

Sullivan, R. H., Cohn, M. M., and Baxter, S. S., "Survey of Facilities
Using Land Application of Wastewater," Report No. 1*30/9-73-006, Jul 1973,
U. S. Environmental Protection Agency, Washington, D. C.

Swindell-Dresser Company, "Process Design Manual for Carbon Adsorption,"
Oct 1971, U. S. Environmental Technology Transfer, Washington, D. C.

Tchobanoglous, F. and Elliassen, R., "Filtration of Treated Sewage Ef-
fluents," Journal, Sanitary Engineering Division, American Society of
Civil Engineers, Vol 96, SA2, 1970.


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 29 Sep 78

Toerber, E. D., "Full Scale Parallel Activated Sludge Process Evalua-
tion," Report No. R2-72-065, Nov 1972, U.  S.  Environmental Protection
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Union Carbide Coporation, "Continued Evaluation of Oxygen Use in Con-
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U.  S.  Environmental Protection Agency, Washington, D. C.

Union Carbide Corporation, "Unox System Wastewater Treatment," Report of
Pilot Study at Hooker's Point Treatment Plant, Tampa, Fla.

Unterberg, W., Sherwood, R. J., and Schnerder, G.  R., "Computerized
Design and Cost Estimation for Multiple Hearth Sludge Incinerators,"
Report No. EP 17070EBP, Jul 1971, Environmental Protection Agency,
Washington, D. C.

U.  S.  Department of Health, Education and Welfare, "Manual of Septic-
Tank Practice," Publication No. (HSM) 72-10020 (formerly Public Health
Service Publication No. 526), 1972, Rockville, Md.

U.  S.  Department of Transportation, "Oxidation Ditch Sewage Waste Treat-
ment Process," Water Supply and Waste Disposal Series, Vol 6, Apr 1972,
U.  S.  Department of Transportation, Washington, D. C.

U.  S.  Environmental Protection Agency, "Process Design Manual for
Phosphorus Removal," Oct 1971, Washington, D. C.

U.  S.  Environmental Protection Agency, Technology Transfer, "Process
Design Manual for Upgrading Existing Wastewater Treatment Plants,"
1973, Washington, D. C.

U.  S.  Environmental Protection Agency, Technology Transfer Seminars,
"Sludge Handling and Disposal," 11-12 Dec 1973, Washington, D. C.

U.  S.  Environmental Protection Agency, "Guidance for Facilities Plan-
ning," Jan 197^, Washington, D. C.

U.  S.  Environmental Protection Agency, Technology Transfer, "Process
Design Manual for Sludge Treatment and Disposal," Oct 197^.

U.  S.  Environmental Protection Agency, Technology Transfer, "Air Pollu-
tion Aspects fo Sludge Incineration," Report No. EQA 625A-75-009, Jun
1975, Washington, D. C.
                                 A-20

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Weber, W. J. , Jr., "Principles and Applications of Adsorption," Manual
of Treatment Processes. Environmental Science Services, Inc., Briarcliff
Manor, New York, 1969.

Weber, W. J., Jr., Physicochemical Processes for Water Quality Control,
Wiley-Interscience, New York, 1972.

Weston, R. F., "Design of Sludge Reaeration Activated Sludge Systems,"
Journal, Water Pollution Control Federation, Vol 33. No.  1  196l
pp 748-757-''      '

White, W. F. and Burns, T. E., "Continuous Centrifugal Treatment of
Sewage Sludge," Water and Sewage Works. Vol 109, Oct 1962, pp 38^-386.

Wukasch, R. F. , "The Dow Process for Phosphorus Removal," Paper pre-
sented at the Federal Water Pollution Control Association Phosphorus
Removal Symposium, Jun 1968, Chicago, 111.

Zeper, J. and DeMan,  A., "New Developments in the Design  of  Activated
Sludge Tanks with Low BOD Loadings," 5th International Water Pollution
Research Conference,  Jul-Aug 1971, San Francisco, Calif.
                                A-22

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                                                           EM 1110-2-501
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                               APPENDIX B

                              ABBREVIATIONS

atm                                     atmosphere
av                                      average
avg                                     average
"bhp                                     brake horsepower
Btu                                     British Thermal Unit
cal                                     calorie
cfs                                     cubic feet per second
cm                                      centimeter
cu ft                                   cubic foot
fpm                                     feet per minute
fps                                     feet per second
ft                                      foot
ft-lb                                   foot-pound
g                                       gram
gal                                     gallon
gpad                                    gallons per acre per day
gpcd                                    gallons per capita per day
gpd                                     gallons per day
gpm                                     gallons per minute
hp                                      horsepower
hr                                      hour
in.                                     inch
mgad                                    million gallons per acre per day
mgd                                     million gallons per day
mg                                      milligram
mg/1                                    milligrams per liter
min                                     minute
ml                                      milliliter
mm                                      millimeter
ppm                                     parts per million
psi                                     pounds per square inch
psia                                    pounds per square inch absolute
psig                                    pounds per square inch gage
rpm                                     revolutions per minute
rps                                     revolutions per second
cfm                                     standard cubic feet per minute
sec                                     second
sq ft                                   square foot
vol                                     volume
                                  B-l

-------
                                                          EM 1110-2-501
                                                            Part 1 of 3
                                                               29 Sep 78
                               APPENDIX C
      CONVERSION FACTORS FOR UNITS OF MEASUREMENT;  DISSOLVED-OXYGEN
         SOLUBILITY DATA; PHYSICAL PROPERTIES OF WATER;  CHEMICAL
                ELEMENTS AND SUBSTANCES;  SPECIFIC WEIGHT

C-l.  Conversion Factors.  U. S.  customary to metric (Si) and metric
(Si) to U.  S.  customary units of measurement.
                                 Length

                             1 inch = 2.5^ cm
                             1 foot = 0.30U8 m
                             1 yard = 0.915 m
             1 mile (U. S. statute) = 1.6093 km
                           1 micron = 39-37 microinches
                       1 millimeter = 0.039^ in.
                       1 centimeter = 0.39^- in.
                            1 meter = 1.093 yd
                        1 kilometer = 0.621U mile

                                  Area
                      1 square inch = 6.^516 cm
                      1 square foot = 0.0929 m
                                              2
                      1 square yard = 0.836l m
                                             2
      1 square mile (U. S. statute) = 2.59 km
                                              2
                             1 acre = k0^6.8 m
                                               2
                1 square centimeter = 0.155 in.
                                              2
                     1 square meter = 1.196 yd
                                 C-l

-------
EM 1110-2-501
Part 1 of 3

 29 Sep 78

                          1 hectare = 2.1*71 acres
                                                P
                 1 square kilometer = 0.386 mile


                                 Volume


                         cuMc inch = 16.39 cm

                         cuMc foot = 0.0283 m3
                                              o
                         cubic yard = 0.76^5 m

                            acre-ft = 1233.5 m3

                          U.  S.  gal = 3.79 I

                          U.  K.  gal = It. 55 i
                                               o
                   cubic centimeter = 0.06l in.

                                             ,3
                        cubic  meter = 1.307 yd"

                              liter = 0.26 U.  S.  gal = 0.22 U.  K.  gal
                                  Mass


                ounce (avoirdupois)  = 28.35 g

                pound (avoirdupois)  = 0.^536 kg

               ton (short,  2000 Ib)  = 907.185 kg

                ton (long,  22^0 Ib)  = 1016.05 kg

                               gram  = 0.0352 oz

                           kilogram  = 2.2 Ib


                                Pressure


              pound per  square  inch  = 689^.757 Pa

              pound per  square  foot  = ^7.88026 Pa
                                             2
                         atmosphere  = 1 kg/cm

    kilogram per  square centimeter  = lU.697 psi
                                 C-2

-------
                                              EM 1110-2-501
                                                Part 1 of 3
                                                  29 Sep 78
                    Velocity
        inch per second = 2.5^ cm/sec
        foot per second = 0.30^8 m/sec
  centimeter per second = 0.39^ in./sec
       meter per second = 1.093 yd/sec

                      Power

           1 horsepower = 0.7^57 kw
     1 Btu (Int. Table) = 1055.056 joules
             1 kilowatt = 1.3^1 hp

                  Miscellaneous
1 cubic foot per second = 28.3 I/sec
          1 mgd (U. S.) = 3780 m3/day
          1 mgd (U. K. ) = 1+550 m3/day
                                      o
   pound per cubic foot = 16.0185 kg/m
    milligram per liter = 0.000138 oz/gal (U. S.)
             centipoise = 0.001 Pa-sec
     pound BOD/acre/day = 1.12 kg BOD/ha/day
      degree Fahrenheit = 5/9 degree Celsius*
*  To obtain Celsius (c) temperature readings
  from Fahrenheit (F) readings,  use the follow-
  ing equation:   C = (5/9)(F - 32).
                     C-3

-------
EM 1110-2-510
Part 1 of 3
 29 Sep 78


C-2.  Physical Properties of Water.
Specific
fT . , , _ ., Viscosity
m Weight, Density,
Temper- & ' •" _, - 5
, Y, 0. u x 10 .
ture




°F lb/ftj slug/ft^ Ib-sec/ft
32 62.1*2
1*0 62.1*3
50 62.1*1
60 62.37
70 62.30
80 62.22
90 62.11
100 62.00
1.
1.
1.
1.
1.
1.
1.
1.
C-3. Dissolved-Oxygen
9l*0
91*0
9l*0
938
936
931*
931
927
3.
3.
2.
2.
2.
1.
1.
1.
Solubility
71*6
229
735
359
050
799
595
421*
Data.
Kinematic
, Viscosity,
v x 10~5.

2









Dissolved Oxygen
Tempera-
ture
°C
0
1
2
3
1*
5
6
7
8
9
10
11
12
13
ll*








ft /sec
1.
1.
1.
1.
1.
0.
0.
0.

931
661*
1*10
217
059
930
826
739










Surface
Tension,
a,
Ib/ft
0.00518
0.00511*
0.00509
0.00501*
0.001*98
0.001*92
0.001*86
o.ooi*8o

Vapor
Pressure,











pu,
psia
0.09
0.12
0.18
0.26
0.36
0.51
0.70
0.95

, mg/£






Chloride Concentration, mg/£
0
UK 62
ll*.23
13. 8U
13.1*8
13.13
12.80
12.1*8
12.17
11.87
11.59
11.33
11.08
10.83
10.60
10.37
















5,000
13.79
13.1*1
13.05
12.72
12.1*1
12.09
11.79
11.51
11.21*
10.97
10.73
10.1*9
10.28
10.05
9.85
















10,
12.
12.
12.
11.
11.
11.
11.
10.
10.
10.
10.
9.
9.
9.
9.
000
97
61
28
98
69
39
12
85
61
36
13
92
72
52
32
















15
12
11
11
11
10
10
10
10
9
9
9
9
9
8
8
,000
.11*
.82
.52
.21*
.97
.70
.U5
.21
.98
.76
.55
.35
.17
• 98
.80
20
11
11
10
10
10
10
9
9
9
9
8
8
8
8
8
,000
.32
.03
• 76
.50
.25
.01
.78
.57
.36
.17
• 98
.80
.62
.1*6
.30
                               (Continued)
                                 c-U

-------
                           EM 1110-2-501
                             Part  1 of 3
                               29 Sep 78
Tempera-
ture
°C
15
16
17
18
19
20
21
22
23
21*
25
26
27
28
29
30
C-l*. Chemical

Element
Aluminum
Bromine
Calcium
Carbon
Chlorine
Chromium
Cobalt
Copper
Fluorine
Hydrogen
Iodine
Iron (Ferrum)





Chloride Concentration, mg/fl.
0
10.15
9-95
9.7^
9-51*
9.35
9.17
8.99
8,83
8.68
8.53
8.38
8.22
8.07
7-92
7.77
7-63
Elements













5 , OOP
9-65
9.1*6
9.26
9-07
8.89
8.73
8.57
8.1*2
8.27
8.12
7.96
7.81
7-67
7.53
7.39
7-25
and Substances

Symbol
Al
Br
Ca
C
Cl
Cr
Co
Cu
F
H
I
Fe
10,000
9. 11!
8.96
8.78
8.62
8.^5
8.30
Q.Ik
7.99
7.85
7-71
7.56
7.1+2
7.28
7.H*
7.00
6.86

Atomic
Number
13
35
20
6
17
2k
27
29
9
1
53
26
15,000
8.63
8.^7
8.30
8.15
8.00
7.86
7.71
7.57
7.^3
7.30
7.15
7.02
6.88
6.75
6.62
6.1*9

Atomic
Weight
26.98
79.92
ho. 08
12.01
35.^6
52.01
58.91*
63.5^
19-00
1.008
126.92
55.85
20,000
8. Ill
7.99
7.81*
7.70
7-56
7.1*2
7.28
7.11+
7.00
6.87
6.71+
6.6l
6.1*9
6.37
6.25
6.13


Valence
3
1,3,5,7
2
2,1*
1,3,5,7
2,3,6
2,3
1,2
1
1
1,3,5,7
2,3
(Continued)
C-5

-------
EM 1110-2-510
Part 1 of 3

 29 Sep 78
Element
Lead ( Plumbum )
Magnesium
Manganese




Mercury (Hydragyrum)
Nickel
Nitrogen
Oxygen
Phosphorus
Platinum
Potassium (Kalium)
Silicon
Silver (Argentum)
Sodium (Natrium)
Strontium
Sulfur
Tin (Stannum)
Zinc













Symbol
Pb
Mg
Mn
Hg
Ni
N
0
P
Pt
K
Si
Ag
Na
Sr
S
Sn
Zn
C-5. Specific Weight (at Standard


Atomic
Number

















82
12
25
80
28
7
8
15
78
19
lU
kl
11
38
16
50
30
Temperature

















Atomic
Weight
207-
2k.
5>i.
200.
58.
1U.
16.
30.
195.
39.
28.
107.
23.
87-
32.
118.
65.
21
32
93
61
69
01
00
98
23
10
09
88
00
63
07
70
38
Valence
2,U
2
2,3,M,7
1,2
2,3
3,5
2
3,5
2,U
1
k
1
1
2
2,1*, 6
2,1*
2
and Pressure).
Specific
Substance

Water

Salt water


Ice
Snow


Gasoline
Diesel oil





Wood
Feces
Dust
Earth
Sand


(loose).
(loose)

Weight
1.
1.
0.
0.
0.
0.
0.
1.
1.
1.
2.
00
02
91
UO
70
90
68
02
20
60
80
Density
62
6k
57
25
hh
56
h2
6k
75
100
175
A3

.5






























                   1 cu ft of water = 62.1*3 lb
                   1 gal of water (U. S.) = 8.3U lb
                   1 m3 of air = 1.2 kg
                   1 kg/a = 62. it3 Ibs/cu ft
                   1 Ib/cu ft = 16.02 kg/m3
                              = 0.012 tons long/cu yd
                                  C-6

-------
                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                                29 Sep 78

                                GLOSSARY

absorption — The taking up of one substance into the body of another.

acid — (l) A substance that tends to lose a proton.   (2) A substance
  that dissolves in water with the formation of hydrogen ions.   (3) A
  substance containing hydrogen which may be replaced by metals to form
  salts.

acidity — The quantitative capacity of aqueous solutions to react with
  hydroxyl ions.  It is measured by titration with a standard solution
  of a base to a specified end point.  Usually expressed as milligrams
  per liter of calcium carbonate.

activated carbon — Carbon particles usually obtained by carbonization
  of cellulosic material in the absence of air and possessing a high
  adsorptive capacity.

activated sludge — Sludge floe produced in raw or settled wastewater
  by the  growth of zoogleal bacteria and other organisms in the pres-
  ence of dissolved oxygen and accumulated in sufficient concentration
  by returning floe previously formed.

activated sludge loading — The pounds  of biochemical oxygen demand
  (BOD) in the applied liquid per unit  volume of aeration capacity or
  per pound of activated sludge per day.

activated sludge process — A biological wastewater treatment process in
  which a mixture of wastewater and activated sludge  is  agitated and
  aerated.  The activated sludge is subsequently separated from the
  treated wastewater (mixed liquor) by  sedimentation  and wasted or
  returned to the process as needed.

adsorption — (l) The adherence of a gas, liquid,  or  dissolved material
  on the  surface of a solid.  (2) A change in concentration of gas or
  solute  at the interface of a two-phase system.   Should not be confused
  with absorption.

advanced  wastewater treatment — Those  processes that achieve pollutant
  reductions by methods other than those used in conventional treatment
  (sedimentation, activated sludge, trickling filter, etc).   It employs
  a number of different unit operations, including lagoons,  post-
  aeration, microstraining, filtration, carbon adsorption,  membrane
  solids  separation, phosphorus removal, and nitrogen removal..


                               Glossary 1

-------
EM 1110-2-501
Part 1 of 3
 29 Sep  78

aerated contact bed — A biological unit consisting of stone,  cement-
  asbestos, or other surfaces supported in an aeration tank,  in which
  air is diffused up and around the surfaces  and settled wastewater
  flows through the tank.  Also called contact aerator.

aerated pond — A natural or artificial wastewater treatment  pond in
  which mechanical or diffused-air aeration is used to supplement the
  oxygen supply.  See oxidation pond.

aeration — (l) The bringing about of intimate contact between air and
  a liquid by one or more of the following methods:  (a) spraying the
  liquid in the air, (b) bubbling air through the liquid, (c)  agitating
  the liquid to promote surface absorption of air.  See following terms
  modifying aeration:  diffused-air, mechanical, modified,  spiral-flow,
  step.

aeration period — (l) The theoretical time,  usually expressed in hours,
  during which, mixed liquor is subjected to aeration in an  aeration tank
  while undergoing activated sludge treatment.  It is equal to the vol-
  ume of the tank divided by the volumetric rate of flow of the waste-
  water and return sludge.  (2) The theoretical time during which water
  is subjected to aeration.

aeration tank — A tank in which sludge, wastewater, or other liquid is
  aerated.

aerator — A device that promotes aeration.

aerobic — Requiring, or not destroyed by, the presence of  free ele-
  ment al oxy gen.

aerobic bacteria — Bacteria that require free elemental oxygen for their
  growth.

aerobic digestion — Digestion of suspended organic matter  by means of
  aeration.  See digestion.

agglomeration — The coalescence of dispersed suspended matter into
  larger floes or particles which settle rapidly.

agitator — (l) Mechanical apparatus for mixing and/or aerating.  (2)  A
  device for creating turbulence.

air —• The mixture of gases that surrounds the earth and forms its


                               Glossary 2

-------
                                                           EM  1110-2-501
                                                             Part 1 of  3
                                                                29 Sep 78

   atmosphere,  composed primarily  of  oxygen and nitrogen.  It also con-
   tains  carbon dioxide,  some water vapor, argon, and traces of other
   gases.

 algae  — Primitive plants, one- or many-celled, usually aquatic, and
   capable of elaborating their foodstuffs by photosynthesis.

 alkali — Any  of  certain soluble  salts, principally sodium, potassium,
   magnesium, and  calcium, that have  the property of combining with acids
   to form neutral salts  and may be used in chemical processes  such as
   water  or wastewater  treatment.

 alkaline  — The condition of water,  wastewater, or soil which contains a
   sufficient amount of alkali substances to raise the pH above 7.0.

 alkalinity —  The capacity of water  to neutralize acids, a property
   imparted by  the water's content of carbonates, bicarbonates, hydrox-
   ides,  and occasionally borates, silicates, and phosphates.   It is
   expressed in milligrams per liter  of equivalent calcium carbonate.

 alum — A common name, in the water  and wastewater treatment field,  for
   commercial-grade aluminum sulfate.

 aluminum  sulfate — A  chemical, formerly sometimes called "waterworks
   alum" in water or wastewater treatment, prepared by combining a min-
   eral known as bauxite with sulfuric acid.

 ammonia — A chemical combination of hydrogen (H) and nitrogen (N)
   occurring extensively in nature.  The combination used in  water and
   wastewater engineering is expressed as NH .

 ammonia stripping — A modification of the aeration process  for removing
   gases in water.   Ammonium ions in wastewater exist in equilibrium
  with ammonia and hydrogen ions.   As pH increases, the equilibrium
   shifts to the right, and above pH 9 ammonia may be liberated as a
   gas by agitating the wastewater in  the presence of air.  This is usu-
  ally done in a packed tower with an air blower.

ammonification — Bacterial decomposition of  organic nitrogen  to
  ammonia.

anaerobic — Requiring, or  not  destroyed by,  the  absence  of air or free
  elemental oxygen.
                               Glossary 3

-------
EM 1110-2-501
Part 1 of 3

 29 Sep 78
anaerobic bacteria — Bacteria that grow only in the absence  of free
  elemental oxygen.

anaerobic contact process — An anaerobic waste treatment  process  in
  which the microorganisms responsible for waste stabilization are re-
  moved from the treated effluent stream by sedimentation  or  other
  means and held in or returned to the process to enhance  the rate of
  treatment.

anaerobic denitrification — A means to remove nitrates from  wastewaters,
  especially irrigation return waters that may be high in  nitrates and
  low in organics.  In this method, an organic chemical such  as meth-
  anol, ethanol, acetone, or acetic acid is added as a carbon source
  and the waste is placed in an anaerobic environment.  Under these
  conditions, nitrate will be reduced by denitrifying bacteria to  nitro-
  gen gas and some nitrous oxide, which escapes to the atmosphere. With
  methanol, the chemistry can be represented as:


               6H+ + 6NO~ + 5CH3OH      5C02 + 3N2 + ISHgO


anaerobic digestion — The degradation of organic matter brought about
  through the action of microorganisms in the absence of elemental oxy-
  gen.

anaerobic digestion of sewage solids — The first stage of the digestion
  is  characterized by the production of organic acids.  Proteins, carbo-
  hydrates, and fats are decomposed by the anaerobic bacteria, and the
  products of the  decomposition  are organic acids.  This digestion stage
  is  evident in sludge by a lowering of the pH and the presence of a
  disagreeable sour odor.  Unless the amount of acid produced  is exces-
  sive, the digestion will normally proceed to the second stage.  With
  excess  acidity,  such as is obtained when the addition of fresh solids
  is  too  rapid, the bacteria will be destroyed and the process will end
  with the first  stage.  The second stage is characterized by  lique-
  faction of sewage  solids under mildly acid conditions.  The  bacteria,
  by  enzyme action,  convert the  insoluble solids material to the  soluble
  form.   This is  in  accordance with the requirements  of the bacterial
  cells that all  food material must be  in solution before it can pass
  through the cell wall.  The third stage of digestion is characterized
  by  production  of gases, carbon dioxide, methane,  and hydrogen sulfide,
  as  well as an  increase  of pH and the  production of  carbonate salts.

 anaerobic waste  treatment — Waste stabilization brought  about through

                               Glossary k

-------
                                                           EM 1110-2-501
                                                             Part  1  of  3

                                                              29 Sep 78
  the action of microorganisms in the absence of air or elemental
  oxygen.   Usually refers to waste treatment  by methane fermentation.

anion — A negatively charged ion in an electrolyte solution, attracted
  to the anode under the influence of electric potential.

anthracite — Coal

available dilution — The ratio of the quantity of untreated wastewater
  or partly or completely treated effluent to the average  quantity of
  diluting water available, effective at the  point of disposal or  at
  any point under consideration; usually expressed in percentage.  Also
  called dilution factor.

average daily flow — The total quantity of liquid tributary to a  point
  divided by the number of days of flow measurement.

average flow — Arithmetic average of flows measured at a  given point.

backwash — The reversal of flow through a rapid sand filter to wash
  clogging material out of the filtering medium and reduce conditions
  causing loss of head.

backwash bed expansion — The expansion that  occurs when a filter  bed
  is being backwashed, usually expressed as a percentage of the back-
  washed and settled bed.

backwashing — The operation of cleaning a filter by reversing the flow
  of liquid through it and washing out matter previously captured  in it.
  Filters would include true filters such as  sand and diatomaceous-
  earth types but not other treatment units such as trickling filters.

bacteria — A group of universally distributed, rigid, essentially uni-
  cellular microscopic organisms lacking chlorophyll.  Bacteria usually
  appear as spheroid, rodlike, or curved entities, but occasionally
  appear as sheets, chains, or branched filaments.  Bacteria are usually
  regarded as plants.

bacteria — See following terms modifying bacteria:  aerobic, anaerobic,
  facultative anaerobic.

baffles — Deflector vanes, guides, grids, gratings, or similar devices
  constructed or placed in flowing water, wastewater, or slurry systems
  to check or effect a more uniform distribution of velocities; absorb
  energy; divert, guide, or agitate the liquids; and check eddies.

                               Glossary 5

-------
EM 1110-2-501
Part 1 of 3

  29  Sep  78
bar screen — In a waste-treatment  plant,  a screen  that  removes  large
  suspended solids.

basin — (l) A natural or artificially created space  or  structure,  sur-
  face or underground, which has a  shape and character of  confining
  material that enable it to hold water.  The term  is sometimes  used for
  a receptacle midway in size between a reservoir and a  tank.   (2)  The
  surface area within a given drainage system.   (3) A small area in an
  irrigated field or plot surrounded by low earth ridges and designed to
  hold irrigation water.  (k) An area upstream from a subsurface or
  surface obstruction to the flow of water.   (5)  A  shallow tank  or  de-
  pression through which liquids may be passed or in  which they  are
  detained for treatment or storage.  Also see tank.

bed — The bottom of a watercourse  or any body of water.

bed density, backwashed and drained (granular carbon  adsorption) —
  The weight per unit volume on a dry basis of a  bed  of  activated
  carbon that has been backwashed and drained.  This  value is  usually
  lower than the corresponding apparent density due to the classifi-
  cation according to size of the carbon granules during backwashing.

bed depth (height) — (l) The depth of carbon,  expressed in length  units,
  which is parallel to the flow of  the stream and through  which  the
  stream must pass.  (2) The depth  of the ion exchange resin in  an  ion
  exchange column.

bed diameter — The diameter of a cylindrical carbon  column or ion  ex-
  change column, measured perpendicular to the stream flow.

bed expansion — The separation and rise of ion exchange resin particles
  in an ion exchange column during  backwashing.

biochemical action — Chemical change resulting from  the metabolism of
  living organisms.

biochemical oxygen demand — A standard test used in  assessing waste-
  water strength.  See BOD.

biodegradation (biodegradability) — The destruction  or  mineralization
  of either natural or synthetic organic materials  by the  microorganisms
  populating soils, natural bodies  of water, or wastewater treatment
  systems.

biological filter — A bed of sand, gravel, broken  stone,  or other

                               Glossary 6

-------
                                                            EM 1110-2-501
                                                              Part 1 of ^
                                                                 29  Sep  78
   medium through which waste-water flows or trickles that depends on bio-
   logical action for its effectiveness.

 biological filtration — The process of passing a liquid through the
   medium of a biological filter, thus permitting contact with attached
   zoogleal films that adsorb and absorb fine suspended, colloidal,  and
   dissolved solids and release end products of biochemical action.

 biologically active floe — Floe formed by the action of biological
   agencies; for example, activated sludge.

 biological oxidation — The process whereby living organisms  in  the
   presence of oxygen convert the organic matter contained in  wastewater
   into a more stable or a mineral form.

 biological process  — (l)  The process  by which the life activities  of
   bacteria and other microorganisms,  in the search for  food,  break  down
   complex organic materials into simple,  more  stable  substances.  Self-
   purification of polluted streams,  sludge  digestion, and all the so-
   called secondary  wastewater treatments  result  from this  process.
   (2)  Process  involving living organisms  and their life  activities.
   Also called  biochemical process.

 biological  purification — The process whereby living organisms convert
   the  organic  matter  contained in wastewater into  a more  stable or a
   mineral form.

 biological  slime — The  gelatinous film of  zoogleal growths covering the
   medium or spanning the interstices of a biological bed.  Also called
   microbial film.

biological treatment systems —  "Living" systems which rely on mixed
   biological cultures to break down waste organics and remove  organic
   matter from  solution.

biological wastewater treatment — Forms of wastewater treatment  in
  which bacterial or biochemical action is intensified to stabilize,
   oxidize, and nitrify the unstable organic matter present. Intermittent
   sand filters, contact beds, trickling filters, and activated sludge
  processes are examples.

BOD — (1) Abbreviation for biochemical oxygen  demand.   The quantity  of
  oxygen used in the biochemical oxidation of organic  matter in. a
  specified time, at a specified temperature, and under  specified
  conditions.   (2) A standard test used in assessing wastewater strength.

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BOD load — The BOD content of vastevater passing into  a waste  treatment
  system or to a body of water, usually expressed in pounds  per unit  of
  time.

breakpoint chlorination — Addition of chlorine  to water or  wastewater
  until the chlorine demand has been satisfied and further additions
  result in a residual that is directly proportional to the  amount
  added beyond the breakpoint.

buffer — Any of certain combinations of chemicals used to stabilize
  the pH values or alkalinities of solutions.

cake — Solids deposited on the filter medium.

cake compressibility factor — Also known as  the coefficient of com-
  pressibility.  An empirically derived factor relating specific resis-
  tance of sludge cake to filtering pressure  (dimensionless).

cake solids -- Percent dry solids in wet cake discharged from a de-
  watering device.  As commonly reported, this includes the  weight of
  sludge conditioning chemicals which may comprise 5 to 15 percent of
  the dry sludge solids.

calcium hypocnlorite — A dry powder consisting  of lime and  chlorine
  combined in such a way that, when dissolved in water, it releases
  active chlorine.

carbonate hardness — Hardness caused by the  presence of carbonates and
  bicarbonates of calcium and magnesium in water.   Such hardness may  be
  removed to the limit of solubility by boiling  the water.   When the
  hardness is numerically greater than the sum of the carbonate alka-
  linity and the bicarbonate alkalinity, that amount of hardness which
  is equivalent to the total alkalinity is called carbonate  hardness.
  See hardness.

cation — The ion in an electrolyte which carries the positive  charge
  and which migrates toward the cathode under the influence  of  a poten-
  tial difference.

centrate — The effluent or liquid portion of a  sludge  removed  by or
  discharged1from a centrifuge.

centrifugal dewatering of sludge — The partial  removal of water from
  wastewater sludge by centrifugal action.


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 centrifugal drying — The partial drying of industrial waste sludge or
  waste-water by centrifugal action.

 centrifuge — A mechanical device in which centrifugal force is used to
  separate solids from liquids and/or to separate liquids of different
  densities.

 channel — A perceptible natural or artificial waterway which period-
  ically or continuously contains moving water or which forms a con-
  necting link between two bodies of water.  It has a definite bed and
  banks which confine the water.

 chemical coagulation — The destabilization and initial aggregation of
  colloidal and finely divided suspended matter by the addition of a
  floe-forming chemical.  See flocculation.

 chemical dose — The application of a specific quantity of chemical to
  a specific quantity of fluid for a specific purpose.  See dose.

 chemical feeder — A device for dispensing a chemical at a predetermined
  rate for the treatment of water or wastewater.   Change in rate of feed
  may be affected manually or automatically by flow-rate changes.
  Feeders are designed for solids, liquids, or gases.

 chemical oxygen demand (COD) — A measure of the  oxygen-consuming  capac-
  ity of inorganic and organic matter present in  water or wastewater.
  It is expressed as the amount of oxygen consumed from a chemical  oxi-
  dant in a specific test.   It does not differentiate  between stable and
  unstable organic matter and thus does not necessarily correlate with
  biochemical oxygen demand.   Also known as OC and DOC, oxygen consumed
  and dichromate oxygen consumed, respectively.

chemical precipitation — (l)  Precipitation induced by addition  of
  chemicals.   (2)  The process  of softening water  by the addition of lime
  or lime and soda ash as the  precipitants.

chemical sludge — Sludge obtained by treatment of wastewater with
  chemicals.

chemical toilet — (l) A commode chair in which a pail containing a
  chemical solution for deodorizing and liquefying fecal matter  is
  placed immediately beneath the seat.   (2)  A nonwater-carriage  toilet
  arranged to discharge fecal  matter directly into a deodorizing and
  liquefying  chemical solution contained in  a watertight  tank.
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chemical treatment — Any process involving the addition of chemicals
  to obtain a desired result.

chlorination — The application of chlorine to water or waste-water,
  generally for the purpose -of disinfection, but frequently for accom-
  plishing other biological or chemical results.

chlorination chamber — A detention basin provided primarily to secure
  the diffusion of chlorine through the liquid.  Also called chlorine
  contact chamber.

chlorine — An element ordinarily existing as a greenish-yellow gas
  about 2.5 times as heavy as air.  At atmospheric pressure and a tem-
  perature of -30.1°F, the gas becomes an amber liquid about 1.5 times
  as heavy as water.  The chemical symbol of chlorine is Cl, its atomic
  weight is 35.^57, and its molecular weight is JO.91^-

chlorine contact chamber — A detention basin provided primarily to
  secure the diffusion of chlorine through the liquid.  Also called
  chlorination chamber.

 chlorine demand — The difference between the amount of chlorine added
  to the wastewater and the amount of residual chlorine remaining at
  the end of a specific contact time.  The chlorine demand for given
  water varies with the amount of chlorine applied, time of contact,
  temperature, pH, nature, and amount of impurities in the water.

 chlorine residual — The total amount of chlorine  (combined and free
  available chlorine) remaining in water, sewage, or industrial wastes
  at the end of a specified contact period following chlorination.

 clarification •— Any process or combination of processes which reduce
  the concentration of suspended matter in a liquid.

 clarified wastewater — Wastewater from which most of the settleable
  solids have been removed by sedimentation.  Also called settled
  wastewater.

 clarifier — A unit which secures clarification.  Usually applied to
  sedimentation tanks or basins.  See sedimentation tank.

 coagulant — A chemical added to wastewater or  sludge to promote agglom-
  eration and flocculation  of suspended solids  to  induce faster
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   settling or more efficient filtration.  Typical coagulants are poly-
   electrolytes, alum, and ferric chloride.

 coagulation — In water and waste-water treatment, the destabilization
   and initial aggregation of colloidal and finely divided suspended
   matter by the addition of a floe-forming chemical or by biological
   processes.

 coagulation basin — A basin used for the coagulation of suspended or
   colloidal matter, with or without the addition of a coagulant, in
   which the liquid is mixed gently to induce agglomeration with a
   consequent increase in settling velocity of particulates.

 coarse screen — Coarse or large screens have openings that range from
   1.5 to 6 inches.  They protect pumps, tanks, automatic dosing de-
   vices, conduits, and valves from large objects such as pieces of
   timber.

 COD — Symbol for chemical oxygen demand.   See chemical oxygen demand.

 colloidal matter — Finely divided solids  which will not settle but may
   be removed by coagulation or biochemical action or membrane filtration.
   See colloids.

 colloids — (l)  Finely divided solids which will not settle but may be
   removed by coagulation or biochemical action or membrane filtration;
   they are intermediate between true solutions and suspensions.   (2) In
   soil physics,  discrete mineral particles less than 2 microns (y)  in
   diameter.   (3)  Finely divided dispersions of one material,  called the
   dispersed phase; with another, called the dispersion medium.   (h)  In
   general, particles of colloidal dimensions are approximately 10 A to
   1 M in size.   Colloidal particles are distinguished from ordinary
  molecules  by their inability to diffuse  through membranes that allow
   ordinary molecules and ions to pass freely.

color — Colors  in water are usually due to decomposition of organic
  matter of vegetable or soil origin.  Color caused by suspended matter
  is referred to  as "apparent color"; color due to colloid vegetable
  or organic  extracts is called "true color."

combined residual chlorination  — The application of chlorine to water
  or wastewater to produce,  with the natural or added ammonia or with
  certain organic  nitrogen compounds, a combined chlorine residual.
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combined wastewater — A mixture of surface runoff and other waste-
  water such as domestic or industrial wastewater.

comminuted solids — Solids which have been divided into fine particles.

comminuting screen — A mechanically operated device for screening waste-
  water and cutting the screenings into particles sufficiently fine to
  pass through the screen openings.

comminution — The process of cutting and screening solids contained in
  wastewater flow before it enters the flow pumps or other units in the
  treatment plant.

comminutor — A device for catching and shredding heavy solid matter in
  the primary stage of waste treatment.

concentrate — To increase the proportion of solids in a sludge or
  wastewater.

concentration — (l) The amount of a given substance dissolved in a unit
  volume of solution.  (2) The process of increasing the dissolved solids
  per unit volume of solution, usually by evaporation of the liquid.

concentration tank — A settling tank of relatively short detention
  period in which sludge is concentrated by sedimentation or flo-
  tation before treatment, dewatering, or disposal.  See sedimentation
  tank.

concentrator — A solids contact unit used to decrease water content of
  sludge or slurry.

conduit — Any artificial or natural duct, either open or closed, for
  conveying liquids or possibly other fluids.

contact aerator — A biological unit consisting of stone, cement-
  asbestos, or other surfaces supported in an aeration tank, in which
  air is diffused up and around the surfaces and settled wastewater
  flows through the tank.

contact bed — (l) An artificial bed of coarse material providing
  extensive surface area for biological growth in a watertight basin.
  Wastewater exposure to the surface may be accomplished by cycling
  or by continuous flow through controlled inlet and outlet.  (2)  An
  early type of wastewater filter consisting of a bed of coarse broken


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   stone or similar inert  material placed in  a watertight tank or basin
   which can "be completely filled with wastewater  and then  emptied.
   Operation consists of filling, allowing the contents to  remain for
   a short time, draining, and then allowing  the bed to rest.   The  cycle
   is then repeated.   A precursor to the  trickling filter.

 contact stabilization process — A modification of the activated sludge
   process in which raw wastewater is  aerated with a high concentration
   of activated sludge for a  short period, usually less than 60 min, to
   obtain BOD removal by absorption.   The solids are subsequently removed
   by sedimentation and transferred to a  stabilization tank where aera-
   tion  is continued  further  to oxidize and condition them before their
   reintroduction to  the raw  wastewater flow.

 contact tank — A  tank used  in water  or  wastewater treatment to promote
   contact between  treatment  chemicals or other materials and the body of
   liquid treated.

 current — (l)  The flowing of water or other fluid.   (2) That portion
   of a  stream of water which  is moving with a velocity much greater than
   the average or in which the progress of the water is principally
   concentrated.

 cycle —  Filtration interval:  length of time filter operates before
   cleaning.

 dechlorination  — The partial or complete reduction  of residual chlorine
   in  a  liquid by any chemical or physical process.

 decomposition — The breakdown of complex material into simpler sub-
   stances by  chemical or biological means.

 decomposition of wastewater — (l) The breakdown of  organic matter  in
  wastewater by bacterial  action, either  aerobic or  anaerobic.
   (2) Transformation of organic or inorganic  materials  contained in
  wastewater through the action of chemical  or biological processes.

defoamant — A material having low compatibility with  foam  and a low
  surface tension.   Defoamants are used to control,  prevent,  or destroy
  various types of  foam, the  most widely  used being  silicone  defoamers.
  A droplet of silicone defoamant which contacts a bubble of  foam will
  cause  the bubble  to undergo a local  and drastic  reduction in film
  strength, thereby breaking  the  film. Unchanged, the  defoamant  con-
  tinues to contact other  bubbles, thus breaking up the foam.  'A val-
  uable  property of most defoamants is their  effectiveness  in  extremely


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  low concentration.  In addition to silicones, defoamants for special
  purposes are based on polyamides, vegetable oils,  and stearic acid.

defoaming agent — A material having low compatibility with foam and
  a low surface tension.  See defoamant.

denitrification —  (l) Chemically bound oxygen in the form of either
  nitrates or nitrites is stripped away for use by microorganisms.   This
  produces nitrogen gas which can bring up floe in the final sedimen-
  tation process.   It is an effective method of removing nitrogen from
  wastewater.  (2) A biological process in which gaseous nitrogen is
  produced from nitrite and nitrate.

depth of side water — The depth of a liquid measured along the inside
  of the vertical exterior wall of a tank.

detention time — The theoretical time required to displace the contents
  of a tank or unit at a given rate of discharge (volume divided by
  rate of discharge).

dewatering — Any process of water removal or concentration of a sludge
  slurry, as by filtration, centrifugation, or drying.    (A dewatering
  method is any process which will concentrate the sludge solids to at
  least 15 percent  solids by weight.)

diatomaceous earth  — A fine, siliceous earth consisting mainly of the
  skeletal remains  of diatoms (unicellular organisms).

diatomaceous-earth  filter — A filter used in water treatment  in which
  a built-up layer  of diatomaceous earth  serves as the filtering medium.

diffused  air — A technique by which air  under pressure is forced into
  sewage  in  an aeration tank.  The air is pumped down  into the sewage
  through a  pipe and  escapes out through  holes in the  side of  the pipe.

diffused-air aeration — Aeration  produced in  a liquid by air  passed
  through a  diffuser.

diffusion aerator —  An  aerator  that blows air under  low  pressure through
   submerged  porous  plates, perforated  pipes,  or other devices  so that
   small air  bubbles rise through the water or wastewater  continuously.

 digested sludge  —  Sludge  digested under  either aerobic or anaerobic
   conditions until  the  volatile  content has  been  reduced  to  the  point  at
  which the  solids  are  relatively  nonputrescible  and inoffensive.

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digester — A tank in which sludge is placed to permit  digestion to
  occur.  Also called sludge digestion tank.   See sludge digestion.

digestion — (l) The biological decomposition of organic matter  in
  sludge, resulting in partial gasification, liquefaction,  and mineral-
  ization.  (2) The process carried out in a digester.   See sludge
  digestion.

digestion chamber — A sludge-digestion tank.  Frequently refers specif-
  ically to the lower or sludge-digestion compartment of an Imhoff tank.

digestion of sludge — Takes place in heated tanks where the material
  can decompose naturally and the odors can be controlled.

digestion tank — A tank in which sludge is placed to permit digestion
  to occur.  See sludge digestion.

diluent — A diluting agent.

dilution — Disposal of wastewater or treated effluent by discharging
  it into a stream or body of water.

discharge — (l) As applied to a stream or conduit, the rate of flow or
  volume of water flowing in the stream or conduit at a given place and
  within a given period of time.  (2) The passing of water or other
  liquid through an opening or along a conduit or channel.   (3)  The
  rate  of flow of water, silt, or other mobile substance which emerges
  from  an opening, pump, or turbine, or passes along a conduit or chan-
  nel,  usually expressed as cubic feet per second, gallons per minute,
  or million gallons per day.

disinfectant — A substance used for disinfection.

disinfected wastewater — Wastewater to which chlorine or other disin-
  fecting agents has been added, during or after treatment, to destroy
  pathogenic organisms.

disinfection — The killing of the larger portion of microorganisms in
  or on a substance with the probability that all pathogenic bacteria
  are killed by the agent used.

disk screen — A  screen in the form  of a circular disk which rotates
  about a central axis perpendicular to its  plane.

dissolved air flotation — A process that adds energy in the form of air


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  bubbles, which become attached to suspended sludge particles,
  increasing the buoyancy of the particles and producing more positive
  flotation.

dissolved oxygen (DO) — The oxygen dissolved in water, wastewater, or
  other liquid, usually expressed in milligrams per liter, parts per
  million, or percent of saturation.

dissolved solids — Theoretically, the anhydrous residues of the dis-
  solved constituents in water.  Actually, the term is defined by the
  method used in determination.  In water and wastewater treatment the
  Standard Methods tests are used.

ditch — A small artificial open channel or waterway constructed through
  earth or rock to convey water.

ditch oxidation — A modification of the activated sludge process or the
  aerated pond, in which the mixture under treatment is circulated in
  an endless ditch and aeration and circulation are produced by a me-
  chanical device such as a Kessener brush.

domestic wastewater — Wastewater derived principally from dwellings,
  business buildings, institutions, and the like.  It may or may not
  contain groundwater, surface water, or storm water.

dose —  (l) The quantity of substance applied to a unit quantity of
  liquid for treatment purposes.  It can be expressed in terms of either
  volume or weight, e.g., pounds per million gallons, parts per million,
  grains per gallon, milligrams per liter, or grams per cubic meter.
  (2) Generally, a quantity of material applied to obtain a specific
  effect.

drum screen — A screen in the form of a cylinder or truncated cone which
  rotates on its axis.

drying bed — A wastewater treatment unit usually containing a bed of
  sand on which sludge is placed to dry by evaporation and drainage.

dumping — A method for solid waste disposal.

effective size — The diameter of the particles, spherical in shape,
  equal in size, and arranged in a given manner, of a hypothetical
  sample of granular material that would have the same transmission
  constant as the actual material under consideration.


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efficiency — (l) The relative results obtained in any operation in rela-
  tion to the energy or effort required to achieve such results.  (2) The
  ratio of the total output to the total input, expressed as a
  percentage.

effluent —  (l) A liquid which flows out of a containing space.
  (2) Wastewater or other liquid, partially or completely treated, or
  in its natural state, flowing out of a reservoir, basin, treatment
  plant, or  industrial treatment plant, or part thereof.

effluent stream — A stream or stretch of stream which receives  water
  from groundwater in the zone of saturation.  The water surface of such
  a stream stands at a lower level than the water table or piezometric
  surface of the groundwater body from which it receives water.

endogenous respiration — An auto-oxidation of cellular material,
  which takes place in the absence of assimilable organic material,  to
  furnish energy required for the replacement of protoplasm.

environment — The physical environment of the world consisting  of the
  atmosphere, the hydrosphere, and the lithosphere.

environmental pollution — The presence of any foreign substance or
  interference (organic, inorganic, radiological, acoustic, or bio-
  logical) in the environment (water, air, or land) which tends  to
  degrade its quality so as to constitute a hazard or impair the use-
  fulness of environmental resources.

equalization — A process by which variations in flow and composition of
  a waste stream are averaged in an equalizing unit.

equalizing basin — A holding basin in which variations in flow  and
  composition of a liquid are averaged.  Also called balancing
  reservoir.

eutrophication — (l) The normally slow aging process by which a lake
  evolves into marsh and ultimately becomes completely filled with
  detritus and disappears.  (2)  The intentional or unintentional en-
  richment of water.

evaporation — (l) The process by which water becomes a vapor at a
  temperature below the boiling  point.   (2) The quantity of water that
  is evaporated;  the rate is expressed in depth of water, measured as
  liquid water,  removed from a specified surface per  unit of time,
  generally in inches or centimeters per day, month,  or year.

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evaporation rate — The quantity of water, expressed in terms of depth
  of liquid water, evaporated from a given water surface per unit of
  time.  It is usually expressed in inches depth per day, month, or
  year,

evapotranspiration — Water withdrawn from soil by evaporation and/or
  plant transpiration.  Considered synonymous with consumptive use.

evapotranspiration potential — Water loss that would occur if there
  never was a deficiency oi water in the soil ±or use by vegetation.

evapotranspiration tank —•  A tank, filled with soil and provided with a
  water supply, in which representative plants are grown to determine
  the amount of water transpired and evaporated from the soil under
  observed climatic conditions.  Sometimes improperly referred to as
  lysimeter.

excess sludge — The sludge produced in an activated sludge treatment
  plant that is not needed  to maintain the process and is withdrawn
  from circulation.

extended aeration — A modification of the activated sludge process
  which provides for aerobic sludge digestion within the aeration sys-
  tem.   The concept envisages the stabilization of organic matter under
  aerobic conditions, disposal of the end products into the air as gases,
  with the plant effluent in the form of finely divided suspended and
  soluble matter.

facultative anaerobic bacteria — Bacteria which can adapt to growth in
  the presence., as well as  in the absence, of oxygen.   May be referred
  to as facultative bacteria.

ferric chloride — A chemical (Fed ) often used for sludge conditioning.

filter — A device or structure for removing solid or colloidal material,
  usually of a type that cannot be removed by sedimentation,  from water,
  wastewater, or other liquid.   The liquid is passed through  a filtering
  medium, usually a granular material but sometimes finely woven cloth,
  unglazed porcelain, or specially prepared paper.   There are many types
  of filters used in water  or wastewater treatment.   See trickling
  filter.

filter bed — (l)  A type of bank revetment consisting of layers of fil-
  tering medium of which the particles gradually increase in  size from

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  the "bottom upward.  Such a filter allows the groundwater to flow
  freely, "but it prevents even the smallest soil particles from being
  washed out.  (2) A tank for water filtration having a false bottom
  covered with sand, as a rapid sand filter.   (3) A pond with sand bed-
  ding, as a sand filter or slow sand filter.

filter cake — The dewatered sludge discharged from the filter, contain-
  ing 65 to 80 percent moisture, depending upon the type of sludge, the
  type of dewatering equipment, and the conditioning of the sludge.

filter cloth — A fabric stretched around the  drum of a vacuum filter.

filtered wastewater — Wastewater that has passed through a mechanical
  filtering process but not through a trickling filter bed.

filter efficiency — The operating results from a filter as measured by
  various criteria such as percentage reduction in suspended matter,
  total solids, biochemical oxygen demand, bacteria, color.

filtering medium — (l) Any material through which water, wastewater, or
  other liquid is passed for the purpose of purification, treatment, or
  conditioning.  (2) A cloth or metal material of some appropriate de-
  sign used to intercept sludge solids in sludge filtration.

filter leaf — A laboratory device for testing potential performance of
a vacuum filter on a sludge.

filter loading — Organically, the pounds of biochemical oxygen demand
  (BOD) in the applied liquid per unit of filter bed area or volume per
  day.  Hydraulically, the quantity of liquid  applied per unit of 'filter
  bed area or volume per day.

filter rate ~- The rate of application of material to some process
  involving filtration, for example, application of wastewater sludge to
  a vacuum filter, wastewater flow to a. trickling filter, water flow to
  a rapid sand filter.

filter run — (l) The interval between the cleaning and washing oper-
  ations of a rapid sand filter.  (2) The interval between the changes
  of the filter medium on a sludge-dewatering  filter.

filter underdrains — A system of underdraining for collecting water
  that has passed through a sand filter or biological bed.

filter wash — The reversal of flow through a  rapid sand filter to wash

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   clogging material out of the filtering medium and reduce conditions
   causing  loss  of head.  See backwash.

 filtrate ~  The liquid which has passed through a filter.

 filtration — The process of passing a liquid through a filtering medium
   (which may consist of granular material, such as sand, magnetite, or
   diatomaceous  earth, finely woven cloth, unglazed porcelain, or spe-
   cially prepared paper) for the removal of suspended or collodial
   matter.

 filtration rate — The rate of application of wastewater to a filter,
   usually  expressed in million gallons per acre per day or gallons per
   minute per square foot.

 final effluent — The effluent from the final treatment unit of a waste-
   water treatment plant.

 final sedimentation — The separation of solids from wastewater in a
   final settling tank.

final sedimentation tank — A tank through which the effluent from a
  trickling filter or an aeration or contact-aeration tank is passed to
  remove the settleable solids.   Also called final settling basin.   See
   sedimentation tank.

final settling tank — A tank through which the effluent from a trick-
  ling filter or an aeration or contact-aeration tank is passed to
  remove the settleable solids.   Also called final settling basin.   See
  sedimentation tank.

fine screen — A relative term,  usually applied to screens with openings
  of less than 1 in.,  but in wastewater treatment  often reserved for
  openings  that may be  1/16 in.

five-day BOD — That part of oxygen demand associated with biochemical
  oxidation of carbonaceous,  as  distinct  from nitrogeneous,  material.
  It is  determined by allowing biochemical oxidation to proceed, under
  conditions specified  in Standard Methods,  for 5  days.

flash dryer — A device  for vaporizing  water  from  partly dewatered  and
  finely divided sludge  through  contact with  a current  of hot  gas  or
  superheated vapor.   It  includes  a squirrel-cage  mill  for separating
  the sludge cake  into  fine particles.


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flash mixer — A device for quickly dispersing chemicals  uniformly
  throughout a liquid.

floe — Small gelatinous masses formed in a liquid by the reaction of a
  coagulant added thereto, through biochemical processes, or  by
  agglomeration.

flocculating tank — A tank used for the formation of floe by the  gentle
  agitation of liquid suspensions, with or without the aid of chemicals.

flocculation — In water and wastewater treatment, the agglomeration of
  colloidal and finely divided suspended matter after coagulation  by
  gentle stirring by either mechanical or hydraulic means.  In biologi-
  cal wastewater treatment where coagulation is not used, agglomeration
  may be accomplished biologically.

flocculation agent — A coagulating substance which, when added to
  water, forms a flocculent precipitate which will entrain suspended
  matter and expedite sedimentation; examples are  alum, ferrous sulfate,
  and lime.

flocculator — (l) A mechanical device to enhance  the formation of floe
  in a liquid.  (2) An apparatus for the formation of floe in water  and
  wastewater.

flotation — The raising of suspended matter to the surface of the
  liquid in a tank as scum—by aeration, the evolution of gas, chemi-
  cals, electrolysis, heat, or bacterial decomposition—and the sub-
  sequent removal of the scum by skimming.

flowing-through time — (l) The time required for  a volume of liquid to
  pass through a basin, identified in terms of the characteristic  being
  measured, such as mean time, modal time,  minimum time.   (2) The  aver-
  age time required for a small volume of liquid to pass  through a basin
  from inlet to outlet.

flow rate — The rate at which a substance is passed through  a system.

flow regulator — A structure installed in a canal, conduit,  or channel
  to control the flow of water or wastewater at intake or to  control the
  water level in a canal, channel, or treatment unit.

flume — (l) An open conduit of wood, masonry, or  metal constructed  on  a
  grade and sometimes elevated.  Sometimes called  aqueduct.   (2) A


                               Glossary 21

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  ravine or gorge with a stream running through it.  (3) To transport in
  a flume, as logs.

foam —  (l) A collection of minute bubbles formed on the surface of a
  liquid by agitation, fermentation, etc.  (2) The frothy substance com-
  posed of an aggregation of bubbles on the surface of liquids by vio-
  lent agitation or by the admission of air bubbles to liquid containing
  surface-active materials, solid particles, or both.

foam separation — The planned frothing of waste-water or wastewater ef-
  fluent as a means of removing excessive amounts of detergent materials,
  through the introduction of air in the form of fine bubbles.  Also
  called form fractionation.

food-to-microorganism ratio — An aeration tank loading parameter.

gravity filter — A rapid sand filter of the open type, the operating
  level of which is placed near the hydraulic grade line of the influent
  and through which the water flows by gravity.

grease — In wastewater, a group of substances including fats, waxes,
  free fatty acids, calcium and magnesium soaps, mineral oils, and
  certain other nonfatty materials.  The type of solvent and method used
  for extraction should be stated for quantitation.

grinding — A process for solid waste handling and disposal by which
  refuse is reduced to less than 2 in.  by a shredder.   Also called
  shredding.

grit — The heavy suspended mineral matter present in water or waste-
  water, such as sand, gravel, cinders.

grit chamber — A detention chamber or an enlargement  of a sewer de-
  signed to reduce the velocity of flow of the liquid to permit the
  separation of mineral from organic solids by differential
  s e diment at i on.

grit collector — A device placed in a grit chamber to convey deposited
  grit to a point of collection.

groundwater — Subsurface water occupying the saturation zone, from
  which wells and springs are fed.  In a strict sense  the term applies
  only to water below the water table.   Also called phreatic water,
  plerotic water.


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 gutter — An artifically surfaced, and generally shallow, waterway pro-
  vided at the margin of a roadway for surface drainage.

 halogen — Any one of the chemically related elements—fluorine, chlo-
  rine, "bromine, iodine, and astatine.

 hardness — A characteristic of water, imparted by salts of calcium,
  magnesium, and iron such as bicarbonates, carbonates, sulfates,
  chlorides, and nitrates, that causes curdling of soap and increased
  consumption of soap, deposition of scale in boilers, damage in some
  industrial processes, and sometimes objectionable taste.  See
  carbonate hardness.

 head loss — The loss in liquid pressure resulting from the passage of
  the solution through a pipe, a channel, or a treatment unit.

 heavy metals — Metals that can be precipitated by hydrogen sulfide in
  acid solution, for example, lead, silver, gold, mercury, bismuth,
  copper.

 high-rate digestion — Accelerated anaerobic digestion resulting pri-
  marily from thorough mixing of digester contents.  May be enhanced by
  thermophilic digestion.

 high-rate filter — A trickling filter operated at a high average daily
  dosing rate, usually between 10 and hd mgd/acre including any recir-
  culation of effluent.

 horizontal-flow tank — A tank or basin, with or without baffles,  in
  which the direction of flow is horizontal.

 humus sludge — (l) Sludge deposited in final or secondary settling
  tanks following trickling filters or contact beds.   (2) Sludge re-
  sembling humus in appearance.

 hydraulic loading — The flow (volume per unit time)  applied to the sur-
  face area of the clarification or biological reactor units (where
  applicable).

hydraulic loss — The loss of head attributable to obstructions,  fric-
  tion, changes in velocity,  and changes in the form of the conduit.

hydraulic radius — The  right cross-sectional area of a stream  of  water
  divided by the length  of that part of its  periphery in contact with


                               Glossary 23

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  its containing conduit; the ratio of area to wetted perimeter.   Also
  called hydraulic mean depth.

hydraulic surface loading influent — (l)  The flow (volume per unit
  time) applied to a unit of surface area  (square ft), applicable to
  trickling filter and filtration processes.  (2) Wastewater or other
  liquid—raw or partially treated—flowing into  a reservoir, basin,
  treatment process, or treatment plant.

impeller — A rotating set of vanes designed to impel rotation of a mass
  of fluid.

impervious — Not allowing, or allowing only with great difficulty, the
  movement of water; impermeable.

incineration — Burning sludge to remove the water and reduce the re-
  maining residues to a safe, nonburnable  ash. The ash can then be
  disposed of safely on land, in some waters, or  into caves or other
  underground locations.

industrial wastes — The liquid wastes from industrial processes, as
  distinct from domestic or sanitary wastes.

industrial wastewater — Wastewater in which industrial wastes pre-
  dominate.  See domestic wastewater, industrial  wastes.

infiltrate — (l) To filter into.  (2) The penetration by a liquid or
  gas of the pores or interstices.

infiltration — (l) The flow or movement of water through the inter-
  stices or pores of a soil or other porous medium.  (2) The quantity
  of groundwater that leaks into a pipe through joints, porous walls,
  or breaks.  (3) The entrance of water from the  ground into a gal-
  lery.   (10 The absorption of liquid by the soil, either as it falls
  as precipitation or from a stream flowing over  the surface.  See
  percolation.

influent — Water, wastewater,  or other liquid flowing into a reservoir,
  basin, or treatment plant, or any unit thereof.

inhibitory toxicity — Any demonstrable inhibitory action of a substance
  on the rate of general metabolism (including rate of reproduction) of
  living organisms.
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inorganic matter — Chemical substances of mineral origin, or more cor-
  rectly, not of "basically carbon structure.

intake — (l) The works or structures at the  head of a conduit into
  which water is diverted.  (2) The process or operation by which water
  is absorbed into the ground and added to the saturation zone.

interface — (l) A stratum of water of varying thickness lying between
  the fresh water above and ocean water below in certain estuaries.
  (2) A boundary layer between two fluids such as liquid-liquid or
  liquid-gas.

intermediate screen — A screen, with openings from 0.25 to 1.5 in.,
  which prepares the waste flow for passage through grit chambers, pri-
  mary sedimentation tanks, and reciprocating pumps.

intermediate treatment — Wastewater-treatment such as aeration or
  chemical treatment, supplementary to primary treatment.

ion — (l) A charged atom, molecule, or radical, the migration of which
  affects the transport of electricity through an electrolyte or, to a
  certain extent through a gas.  (2) An atom or molecule that has lost
  or gained one or more electrons.  By such ionization it becomes electri-
  cally charged.  An example is the alpha particle.

ion exchange — (l) A chemical process involving reversible interchange
  of ions between a liquid and a solid but no radical change in struc-
  ture of the solid.  (2) A chemical process  in which ions from two
  different molecules are exchanged.

ion-exchange treatment — The use of ion-exchange materials such as
  resin or zeolites to remove undesirable ions from a liquid and sub-
  stitute acceptable ions.

irrigation — The artificial application of water to lands to meet the
  water needs of growing plants not met by rainfall.

isotherm — A line drawn through all points having the same temperature.

kinematic viscosity — Ratio of absolute viscosity, expressed in poises
  (grams per centimeter second), to the density, in grams per cubic
  centimeter, at room temperature.

lagoon — A pond containing raw or partially  treated wastewater in which


                              Glossary 25

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   aerobic or  anaerobic  stabilization occurs.

 land disposal — Disposal of waste-water onto land.

 lime — Any of a family of chemicals consisting essentially of calcium
   hydroxide made from limestone  (calcite) which is composed almost
   wholly  of calcium carbonate or a mixture of calcium and magnesium
   carbonate.

 liquid  — A substance that flows freely.  Characterized by free movement
   of the  constituent molecules among themselves, but without the ten-
   dency to separate from one another characteristic of gases.  Liquid
   and fluid are often used synonymously, but fluid has the broader sig-
   nificance,  including  both liquids and gases.

 liquid  sludge  — Sludge containing sufficient water (ordinarily more
   than  85  percent) to permit flow by gravity or pumping.

 liquor  —  Water, wastewater, or any combination; commonly used to desig-
   nate  liquid phase when other phases are present.

 load -- See following terms modifying load:  BOD, peak, pollutional.

 loading —  The time rate at which material is applied to a treatment de-
   vice  involving length, area, or volume, or other design factor.

 mechanical  aeration —  (l) The mixing, by mechanical means, of wastewater
   and activated sludge  in the aeration tank of the activated sludge
   process to bring fresh surfaces of liquid into contact with the atmo-
   sphere.    (2) The introduction of atmospheric oxygen into a liquid by
   the mechanical action of paddle, paddle wheel, spray, or turbine
   mechanisms.

mechanical  aerator — A mechanical device for the introduction of atmo-
   spheric oxygen into a liquid.   See mechanical aeration.

mechanical  agitation — The introduction of atmospheric oxygen into a
   liquid by the mechanical action of paddle, paddle wheel, spray, or
   turbine mechanisms.   Also see mechanical aeration.

mechanically cleaned screen — A screen equipped with mechanical clean-
   ing apparatus for removal of retained solids.

membrane filtration — A method of quantitative or qualitative analysis
   of bacterial or particulate matter in a water sample by filtration


                              Glossary 26

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   through a membrane capable of retaining bacteria.

 mesh screen — A screen composed of woven fabric  of  any of various
   materials.

 methane fermentation — Fermentation resulting  in conversion  of  organic
   matter into methane gas.

 microbial activity — Chemical changes  resulting  from the  metabolism of
   living organisms.   Biochemical action.

 microbial film — A gelatinous film of  microbial  growth attached to or
   spanning the interstices  of a support medium.   Also called  biological
   slime.

 microbiology  — Study of very small units  of living matter and their
   processes.

 micron  — Unit of length:   10   meters; 39 x 10    j_n.

 microorganism — Minute  organism, either plant or  animal,  invisible  or
   barely visible to  the  naked eye.

 milligrams  per liter —  A unit  of the concentration of  water  or waste-
   water constituent.   It is  0.001 g of  the constituent  in  1,000 ml  of
   water.   It  has replaced the unit  formerly used commonly, parts per
   million,  to which  it is approximately equivalent, in  reporting the
   results  of  water and wastewater analysis.

 minimum flow  —  The  flow occurring  in a stream during the  driest period
   of the year.   Also  called  low flow.

 mixed liquor  —  A mixture of  activated  sludge and organic matter under-
   going activated sludge treatment  in the aeration tank.

 mixed-liquor volatile suspended  solids  (MLVSS) — The concentration of
   volatile  suspended  solids in an aeration basin.   It is commonly as-
   sumed to  equal the biological  solids concentration in the basin.

 mixing basin —  (l) A basin or tank wherein agitation is applied to wa-
   ter, wastewater, or sludge to increase the dispersion rate of applied
   chemicals.   (2) A tank used for general mixing purposes.

mixing tank — A tank designed to provide a thorough mixing of chemicals


                               Glossary 27

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  introduced into liquids or of two or more liquids of different
  characteristics.

modified aeration — A modification of the activated sludge process in
  which a shortened period of aeration is used with a reduced quantity
  of suspended solids in the mixed liquor.

moisture — Condensed or diffused liquid, especially water.

moisture content — The quantity of water present in soil, wastewater
  sludge, industrial waste sludge, and screenings, usually expressed in
  percentage of wet weight.

municipal waste — The combined residential and commercial waste mate-
  rials generated in a given municipal area.

natural water — Water as it occurs in its natural state, usually con-
  taining other solid, liquid, or gaseous materials in solution or
  suspension.

neutralization — Reaction of acid or alkali with the opposite reagent
  until the concentrations of hydrogen and hydroxyl ions in the solution
  are approximately equal.

nitrification — (l) The conversion of nitrogenous matter into nitrates
  "by "bacteria.  (2) The treatment of a material with nitric acid.

Nitrosomonas — A genus of bacteria that oxidize ammonia to nitrite.

nonbiodegradable — Incapable of being broken down into innocuous prod-
  ucts by the actions of living beings (especially microorganisms).

nonpotable water — Water which is unsatisfactory for consumption.

nonsettleable matter — That suspended matter which does not settle nor
  float to the surface of water in a period of 1 hr.

nonsettleable solids — Wastewater matter that will stay in suspension
  for an extended period of time.  Such period may be arbitrarily taken
  for testing purposes as 1 hr.  See suspended solids.

nutrient —  (l) Any substance assimilated by organisms which promotes
  growth and replacement of cellular constituents.  (2) A chemical sub-
  stance  (an element or an inorganic compound, e.g., nitrogen or phos-
  phate) absorbed by a green plant and used in organic synthesis.


                               Glossary 28

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 odor control — (l) In water treatment,  the elimination or reduction of
   odors in a water supply by aeration,  algae elimination,  superchlorina-
   tion, activated carbon treatment,  and other methods.   (2) In waste-
   water treatment, the prevention or reduction of objectionable odors by
   chlorination, aeration, or other processes or by masking with chemical
   aerosols.

 organic loading — Pounds of BOD applied per day to a biological reactor.

 organic matter — Chemical substances of animal or vegetable  origin,  or
   more correctly, of basically carbon structure,  comprising compounds
   consisting of hydrocarbons and their derivatives.

 organic-matter degradation — The conversion of organic matter  to  inor-
   ganic forms by biological action.

 orthophosphate — An acid or salt  containing phosphorus as  PO,.

 overflow —  (l)  The  excess  water  that overflows the  ordinary  limits such
   as the streambanks,  the  spillway crest, or  the  ordinary level  of a
   container.  (2)  To  cover  or inundate with water  or  other fluid.

 overflow rate —  One  of the  criteria for the  design  of settling  tanks in
   treatment  plants;  expressed  in  gallons per  day per square foot of sur-
   face  area  in the settling  tank.

 overland runoff — Water flowing over the land  surface before it reaches
   a definite  stream  channel  or body of water.

 oxidation —  The addition of oxygen to a compound.  More generally, any
   reaction which involves the loss of electrons from an atom.

 oxidation pond — A basin used for retention of wastewater before final
   disposal, in which biological oxidation of organic material is ef-
   fected by natural or artificially accelerated transfer of oxygen to
  the water from air.

oxidation process — Any method of wastewater treatment  for the oxi-
  dation of the putrescible organic matter.   The usual methods are
  biological filtration and the activated sludge process.

oxidation rate — The rate at which the  organic matter in wastewater is
  stabilized.
                               Glossary 29

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oxidized sludge — The liquid and solid product of the wet air oxidation
  of wastewater sludge.

oxidized waste-water — Wastewater in which the organic matter has been
  stabilized.

oxygen demand — (l) The quantity of oxygen utilized in the biochemical
  oxidation of organic matter in a specified time, at a specified tem-
  perature, and under specified conditions.  See BOD.

oxygen saturation — The maximum quantity of dissolved oxygen that
  liquid of given chemical characteristics, in equilibrium with the
  atmosphere, can contain at a given temperature and pressure.

ozone — Oxygen in molecular form with three atoms of oxygen forming
  each molecule (0  ).

Parshall flume — A calibrated device developed by Parshall for meas-
  uring the  flow of liquid in an open conduit.  It consists essentially
  of a contracting length, a throat, and an expanding length.  At the
  throat is a sill over which the flow passes at Belanger's critical
  depth.  The upper and lower heads are each measured at a definite
  distance from the sill.  The lower head need not be measured unless
  the sill is submerged more than about 67 percent.

particle — Any dispersed matter, solid or liquid, in which the indi-
  vidual aggregates are larger than single small molecules (about
  0.0002 mm  in diameter), but smaller than about 500 um in diameter.

particle size — (l) An expression for the size of liquid or  solid
  particles  expressed  as the average or equivalent diameter.   (2) The
  sizes of the two  screens, either in the U.S. Sieve Series or the Tyler
  Series between which the bulk of a carbon sample falls, e.g., 8 x  30
  means most of the carbon passes a No. 8  screen but is retained on  a
  Wo. 30 screen.

parts per million — The number of weight  or volume units of  a minor
  constituent present  with each one million units of the major con-
  stituent of a solution or mixture.  Formerly used to express the
  results of most water and wastewater analyses, but more recently
  replaced by the ratio milligrams per liter.

pathogens — Pathogenic or disease-producing organisms.

peak  demand  — The  maximum momentary load  placed  on  a water or wastewater
                       •
                              Glossary 30

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                                                           EM 1110-2-501
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  plant or pumping station or on an electric generating plant or
  system.  This is usually the maximum average load in 1 hr or less,
  but may be specified as instantaneous or with some other short time
  period.

peak load — (l) The maximum average load carried by an electric gener-
  ating plant or system for a short time period such as 1 hr or less.
  See peak.  (2) The maximum demand for water placed on a pumping
  station, treatment plant, or distribution system, expressed as a rate.
  (3) The maximum rate of flow of wastewater to a pumping station or
  treatment plant.  Also called peak demand.

percolating filter — A type of trickling filter.

percolation — (l) The flow or trickling of a liquid downward through a
  contact or filtering medium.  The liquid may or may not fill the pores
  of the medium.  Also called filtration.  (2) The movement or flow of
  water through the interstices or the pores of a soil or other porous
  medium.

pH — The reciprocal of the logarithm of the hydrogen-ion concentration.
  The concentration is the weight of hydrogen ions, in grams, per liter
  of solution.   Neutral water, for example, has a pH value of 7 and a
  hydrogen-ion concentration of 10~7.

phosphate — A salt or ester of phosphoric acid.

pipe gallery — (l) Any conduit for pipe, usually of a size to allow a
  man to walk through.  (2) A gallery provided in a treatment plant for
  the installation of the conduits and valves and for a passageway to
  provide access to them.

pit privy — A privy placed directly over an excavation in the ground.

pollution — A condition created by the presence  of harmful or object-
  ionable material in water.

pollutional load — (l) The quantity of material  in a waste stream that
  requires treatment or exerts an adverse effect  on the receiving system.
  (2) The quantity of material carried in a body  of water that exerts a
  detrimental effect on some subsequent use of that water.

polyelectrolytes — Long-chained, ionic, high molecular weight,



                               Glossary 31

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  synthetic, water soluble, organic coagulants.   Also referred to as
  polymers.

polymers — Long-chained, high molecular weight,  synthetic,  water sol-
  uble, organic coagulants.  Polymers can "be classified as nonionic,
  cationic, and anionic.

porous — Having small passages; permeable by fluids.

postchlorination — The application of chlorine  to water or wastewater
  subsequent to any treatment, including prechlorination.

potable water — Water that does not contain objectional pollution, con-
  tamination, minerals, or infective agents and  is considered satis-
  factory for domestic consumption.

preaeration — A preparatory treatment of wastewater consisting of aera-
  tion to reirove gases, add oxygen, promote flotation of grease, and aid
  coagulation.

prechlorination — The application of chlorine to water or wastewater
  prior to any treatment.

precipitation —  (l) The total measurable supply of water received
  directly from clouds as rain, snow, hail, or sleet; usually expressed
  as depth in a day, month, or year, and designated as daily, monthly,
  or annual precipitation.  (2) The process by which atmospheric mois-
  ture  is discharged onto a land or water surface.   (3) The phenomenon
  that  occurs when a substance held in solution in a liquid passes out
  of solution into solid form.

preliminary filter — A  filter used in a water treatment plant  for the
  partial removal of turbidity before final filtration.  Such filters
  are  usually of  the rapid type, and their use allows  final filtration
  at a more rapid rate  or reduces  or removes the necessity of other
  preliminary treatment  of the water.  Also called contact filter,  con-
  tact  roughing filte-r,  roughing filter.

preliminary treatment —  (l)  The conditioning of a waste at its source
  before  discharge, to  remove or to neutralize substances injurious to
  sewers  and treatment  processes or to effect a partial  reduction  in
  load on the treatment  process.   (2) In  the treatment process, unit
  operations,  such as  screening and  comminution, that  prepare the  liquor
  for  subsequent  major  operations.

                                Glossary  32

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presettling — The process of sedimentation applied to a liquid before
  subsequent treatment.

pressure regulator — A device for controlling pressure in a pipeline
  or pressurized tank, such as a pressure-regulating valve or a pump
  drive-speed controller.

primary settling tank — The first settling tank for the removal of
  settleable soils through which wastewater is passed in a treatment
  works.

primary sludge — Sludge obtained from a primary settling tank.

primary treatment — (l) The first major (sometimes the only) treatment
  in a wastewater treatment works, usually sedimentation.  (2) The
  removal of a substantial amount of suspended matter but little or no
  colloidal and dissolved matter.

privy — A building, either portable or fixed directly to a pit or
  vault, equipped with seating and used for excretion of bodily wastes.

privy vault — A concrete or masonry vault that is provided with a
  cleanout opening and over which is placed a privy building containing
  seats.

proportional weir — A special type of weir in which the discharge
  through the weir is directly proportional to the head.

public water supply — A water supply from which water is available to
  the people at large or to any considerable number of members of the
  public indiscriminately.

pumping station — A station housing relatively large pumps and their
  accessories.   Pump house is the usual term for shelters for small
  water pumps.

purification — The removal of objectionable matter from water by
  natural or artificial methods.

putrefaction — Biological decomposition of organic matter with the
  production of ill-smelling products associated with anaerobic
  conditions.

radiation — The emission and propagation of energy through space or


                               Glossary 33

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  through a material medium; also, the energy so propagated.

rakings — The screenings or trash removed from bar screens cleaned man-
  ually or by mechanical rakes.

rapid filter — A rapid sand filter or pressure filter.

rapid sand filter — A filter for the purification of water,  in which
  water that has been previously treated, usually by coagulation and
  sedimentation, is passed downward through a filtering  medium.  The
  medium consists of a layer of sand, prepared anthracite coal, or other
  suitable material, usually 2^-30 in. thick, resting on a supporting
  bed of gravel or a porous medium such as carborundum.   It is char-
  acterized by a rapid rate of filtration, commonly from two  to three
  gallons per minute per square foot of filter area.

raw sludge — Settled sludge promptly removed from sedimentation tanks
  before decomposition has much advanced.  Frequently referred to as
  undigested sludge.

raw wastewater — Wastewater before it receives any treatment.

receiving body of water — A natural watercourse, lake,  or ocean into
  which treated or untreated wastewater is discharged.

recycling — An operation in which a substance is passed through the
  same series of processes, pipes, or vessels more than  once.

regeneration — (l) In ion exchange, the process of restoring an ion-
  exchange material to the state employed for adsorption.  (2) The
  periodic restoration of exchange capacity of ion-exchange media used
  in water treatment.

regeneration efficiency — In ion exchange, regeneration level divided
  by breakthrough capacity.

resinous anion exchangers — Organic polymers consisting of amines and
  quaternary ammonium compounds.   They may be regenerated by  any
  caustic.

resinous cation exchangers — Synthetic organic polymers generally of
  the sulfonated polystyrene type produced in a granular or beadlike
  form and in an effective size and uniformity coefficient comparable
  to that specified for filter sand.


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retention — That part of the precipitation falling on a drainage area
  which does not escape as surface streamflow, during a given period,
  It is the difference between total precipitation and total runoff
  during the period, and represents evaporation, transpiration, sub-
  surface leakage, infiltration, and, when short periods are consid-
  ered, temporary surface or underground storage on the area.

returned sludge — Settled activated sludge returned to mix with in-
  coming raw or primary settled wastewater.

Reynolds' number — A numerical quantity used to characterize the type
  of flow in a hydraulic structure where resistance to motion depends
  on the viscosity of the liquid in conjunction with the resisting force
  of inertia.  It is equal to the ratio of inertia forces to viscous
  forces.  It is equal to the product of a characteristic velocity of
  the system (it may be the mean, surface, or maximum velocity) and a
  characteristic linear dimension, such as diameter or depth, divided
  by the kinematic viscosity of the liquid; all expressed in consistent
  units in order that the combinations will be dimensionless.  The
  number is chiefly applicable to closed systems of flow, such as pipes
  or conduits where there is no free water surface, or to bodies fully
  immersed in the fluid so the free surface need not be considered.

rotary distributor — A movable distributor made up of horizontal arms
  that extend to the edge of the circular trickling filter bed, revolve
  about a central post, and distribute liquid over the bed through
  orifices in the arms.  The jet action of the discharging liquid nor-
  mally supplies the motive power.

rotary dryer — A long steel cylinder, slowly revolving, with its long
  axis slightly inclined; through which passes the material to be dried
  in hot air.  The material passes through from inlet to outlet, tum-
  bling about.

runoff — (l) That portion of the earth's available water supply that
  is transmitted through natural surface channels.  (2) Total quantity
  of runoff water during a specified time.  (3) In the general sense,
  that portion of the precipitation which is not absorbed by the deep
  strata, but finds its way into the streams after meeting the per-
  sistent demands of evapotranspiration, including interception and
  other losses.  (h) The discharge of water in surface streams, usu-
  ally expressed in inches depth on the drainage area, or as volume
  in such terms as cubic feet or acre-feet.  (5) That part of the
  precipitation which runs off the surface of a drainage area and
  reaches a stream or other body of water or a drain or sewer.


                               Glossary 35

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sand filter — A filter in which sand is used as a filtering medium.
  Also see rapid sand filter, slow sand filter.

scale — An accumulation of solid material precipitated out of
  waters containing certain mineral salts in solution and formed on
  interior surfaces, such as those of pipelines, tanks, "boilers, under
  certain physical conditions.  May also "be formed from interaction of
  water with metallic pipe.

screen — A device with openings, generally of uniform size, used
  to retain or remove suspended or floating solids in flowing water or
  wastewater and to prevent them from entering an intake or passing a
  given point in a conduit.  The screening element may consist of
  parallel bars, rods, wires, grating, wire mesh, or perforated plate,
  and the openings may be of any shape, although they are usually cir-
  cular or rectangular.

screening — The removal of relatively coarse floating and suspended
  solids by straining through racks or screens.

screenings — Material removed from liquids by screens.

screenings dewatering — The removal of a large part of the water con-
  tent of waste screenings by draining or by mechanical means.

screenings grinder — A device for grinding, shredding, or macerating
  material removed from wastewater by screens.

screenings shredder — A device that disintegrates screenings.

screw-feed pump — A pump with either horizontal or vertical cylindri-
  cal casing, in which operates a runner with radial blades like those
  of a ship's propeller.

scum —  (l) The layer or film of extraneous or foreign matter that rises
  to the surface of a liquid and is formed there.  (2) A residue de-
  posited on a container or channel at the water surface.   (3) A mass
  of solid matter that floats on the surface.

secondary settling tank — A tank through which effluent from some
  prior treatment process flows for the purpose of removing settleable
  solids.  See sedimentation tank.

secondary wastewater treatment — The treatment of wastewater by bio-
  logical methods after primary treatment by sedimentation.


                              Glossary  36

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                                                          EM  1110-2-501
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                                                            29 Sep 78
sedimentation — The process  of subsidence  and  deposition  of sus-
  pended matter carried by water,  waste-water, or  other  liquids, by
  gravity.   It is usually accomplished by reducing  the  velocity of the
  liquid below the point at which  it  can transport  the  suspended ma-
  terial.  Also called settling.   See chemical  precipitation.

sedimentation basin — A basin or  tank in which water or wastewater con-
  taining settleable solids is retained to  remove by gravity a part of
  the suspended matter.  Also called  sedimentation  tank, settling  basin,
  settling tank.

sedimentation tank — A basin or tank in which  water or wastewater con-
  taining settleable solids is retained to  remove by gravity a part of
  the suspended matter.  Also called  sedimentation  basin,  settling
  basin, settling tank.

septicity — A condition produced  by  growth of  anaerobic organisms.

septicization -- In anaerobic decomposition, the  process whereby in-
  tensive growths of bacteria with the enzymes  secreted by them liquify
  and gasify solid organic matter.

septic sludge — Sludge from  a septic tank  or partially digested sludge
  from an Imhoff tank or sludge-digestion tank.

septic tank — A settling tank in  which settled sludge  is  in immediate
  contact with the wastewater flowing through the tank  and the organic
  solids are decomposed by anaerobic  bacterial  action.

septic wastewater — Wastewater undergoing  putrefaction under  anaerobic
  conditions.

settleability test — A determination of the settleability of  solids  in
  a suspension by measuring the volume of solids  settled out of a
  measured volume of sample in a specified  interval of  time, usually
  reported in milliliters per liter.   Sometimes identified as  the  Imhoff
  cone test.

settleable solids — (l) That matter  in wastewater  which will  not  stay
  in suspension during a preselected settling period,  such as  1 hr,
  but either settles to the bottom or floats to the top.   (2)  In the
  Imhoff cone test, the volume of matter that settles to the bottom  of
  the cone in 1 hr.

settled wastewater — Wastewater from which most  of the settleable

                               Glossary 37

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 EM 1110-2-501
 Part  1  of  3
 29  Sep  78

   solids have been removed by sedimentation.  Also called clarified
   wastewater.

 settling — The process of subsidence and deposition of suspended matter
   carried by water, wastewater, or other liquids, by gravity.  It is
   usually accomplished by reducing the velocity of the liquid below the
   point at which it can transport the suspended material.  Also called
   sedimentation.  See chemical precipitation.

 settling basin — A basin or tank in which water or wastewater contain-
   ing settleable solids is retained to remove by gravity a part of the
   suspended matter.  Also called sedimentation basin, sedimentation
  tank, settling tank.

 settling solids — Solids that are settling in sedimentation tanks or
   sedimentation chambers and other such tanks that are constructed for
  the purpose of removing this fraction of suspended solids.  See
   settleable s_olids.

 settling tank -- A basin or bank in which water or wastewater containing
   settleable solids is retained to remove by gravity a part of the sus-
  pended matter.  Also called sedimentation basin, sedimentation tank,
  settling basin.

 settling velocity — The velocity at which subsidence and deposition of
  the settleable suspended solids in water and wastewater will occur.

 sewage — The spent water of a community.   Term now being replaced in
  technical usage by preferable term wastewater..   See wastewater.

 sewer — A pipe or conduit that carries wastewater or drainage water.

 sewer gas — Gas evolved in sewers that results from the decomposi-
  tion of the organic matter in the wastewater.

sharp-crested weir — A weir having a crest, usually consisting of a
  thin plate (generally of metal), so sharp that'the water in passing
  over it touches  only a line.

short-circuiting — A hydraulic condition  occurring in parts of a tank
  where the time of travel is less than the flowing-through time.

shredder — A device  for size reduction.

shredding — A process for the  treatment  and handling of solid wastes.


                              Glossary 38

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                                                           EM 1110-2-501
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                                                              29 Sep 78

  The refuse is reduced to particles having no greater dimension than
  2 in. "by a shredder.   Also called grinding.

side water depth — The depth of water measured along a vertical ex-
  terior wall.

skimming — The process of removing floating grease or scum from the
  surface of wastewater in a tank.

skimmings — Grease, solids, liquids, and scum skimmed from wastewater
  settling tanks.

skimming tank — A tank so designed that floating matter will rise arid
  remain on the surface of the wastewater until removed, while the liq-
  uid discharges continuously under curtain walls or scum "boards.

slimes — Substances of viscous organic nature, usually formed from
  microbiological growth.

slow sand filter — A filter for the purification of water in which
  water without previous treatment  is passed downward through a filter-
  ing medium consisting of a layer  of sand or  other suitable material,
  usually finer than for a rapid sand filter and from 2h to hO in.
  thick.  It is characterized by a  slow rate of filtration, commonly
  3-6 mgd/acre of filter area.

sludge — (l) The accumulated solids separated from liquids, such as
  water or wastewater,  during processing, or deposits on bottoms of
  streams or other bodies of water.   (2) The precipitate resulting from
  chemical treatment, coagulation,  or sedimentation of water or
  wastewater.

sludge bed — An area comprising natural or artificial layers of porous
  material on which digested wastewater sludge is dried by drainage and
  evaporation.  A sludge bed may be open to the atmosphere or covered,
  usually with a greenhouse-type superstructure.   Also called sludge
  drying bed.

sludge blanket — Accumulation of sludge hydrodynamically suspended
  within an enclosed body of water  or wastewater.

sludge cake — The sludge that has  been dewatered by a treatment process
  to a moisture content of 60-85 percent, depending on type of sludge
  and manner of treatment.


                               Glossary 39

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29 Sep 78

sludge circulation — The overturning of sludge in sludge-digestion
  tanks by mechanical or hydraulic means or by use of gas recirculation
  to disperse scum layers and to promote digestion.

sludge collector — A mechanical device for scraping the sludge on the
  bottom of a settling tank to a sump from which it  can be drawn.

sludge concentration — Any process of reducing the  water content of
  sludge that leaves the sludge in a fluid condition.

sludge conditioning — Treatment of liquid sludge before dewatering to
  facilitate dewatering and enhance drainability, usually by the addi-
  tion of chemicals.

sludge density index — The reciprocal of the sludge volume index multi-
  plied by 100.

sludge dewatering — The process of removing a part  of the water in
  sludge by any method such as draining, evaporation, pressing, vacuum
  filtration, centrifuging, exhausting, passing between rollers, acid
  flotation, or dissolved-air flotation with or without heat.  It in-
  volves reducing from a liquid to a spadable condition rather than
  merely changing the density of the liquid (concentration) on the one
  hand or drying (as in a kiln) on the other.

sludge digestion — The process by which organic or volatile matter in
  sludge is gasified, liquified, mineralized, or converted into more
  stable organic matter through the activities of either anaerobic or
  aerobic organisms.

sludge-digestion gas — Gas resulting from the decomposition of organic
  matter in sludge removed from wastewater and placed in a tank to
  decompose under anaerobic conditions.  Also see sewage gas, sludge
  digestion.

sludge-digestion tank — A tank in which sludge is placed for the pur-
  pose of permitting digestion to occur.  See sludge digestion.

sludge dryer — A device for removal of a large percentage of moisture
  from sludge or screenings by heat.

sludge drying — The process of removing a large percentage  of moisture
  from sludge by drainage or evaporation by any method.

sludge filter — A  device in which wet  sludge, usually  conditioned by

                               Glossary i;0

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                             29 Sep 78
  a coagulant, is partly dewatered by vacuum or pressure.
sludge foaming — An increase in the gas in sludge in Imhoff and sepa-
  rate digestion tanks, causing large quantities of froth,  scum, and
  sludge to rise and overflow from openings at or near the  top of the
  tanks.

sludge lagoon — A basin used for the storage, digestion,  or dewatering
  of sludge.

sludge reaeration — The continuous aeration of sludge after its ini-
  tial aeration for the purpose of improving or maintaining its
  condition.

sludge reduction — The reduction in quantity and change in character
  of sludge as the result of digestion.

sludge solids — Dissolved and suspended solids in sludge.

sludge thickener — A tank or other equipment designed to  concentrate
  wastewater sludges.

sludge thickening — The increase in solids concentration  of sludge in
  a sedimentation or digestion tank.   See sludge concentration.

sludge treatment — The processing of wastewater sludges to render them
  innocuous.  This may be done by aerobic or anaerobic digestion fol-
  lowed by drying on sand beds, filtering, and incineration, filtering
  and drying, or wet air oxidation.

sludge utilization — The use of wastewater sludges as soil builders
  and fertilizer admixtures.  Sludges produced by aerobic  and anaerobic
  digestion and activated sludge are used for these purposes.

sludge volume index (SVI) — The ratio of the volume in milliliters of
  sludge settled from a 1,000-ml sample  in 30 min to the concentration
  of mixed liquor in milligrams per liter multiplied by 1,000.

slurry — A thin watery mud, or any substance resembling it, such as
  a lime slurry.

sodium carbonate — A salt used in water treatment to increase the
  alkalinity or pH value of water or to  neutralize acidity.   Chemical
  symbol is Na -CO .   Also called soda ash.


                                Glossary Ul

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EM 1110-2-501
Part 1 of 3

29 iep 78
solids-retention time — The average residence time of suspended soils
  in a biological waste treatment system, equal to the total weight of
  suspended solids in the system divided "by the total weight of sus-
  pended solids leaving the system per unit of time (usually per
  day).

specific gravity — The ratio of the mass of a body to the mass of an
  equal volume of water.

specific resistance — A sludge filterability index, generally ex-
  pressed as sec^/g.

spiral air-flow diffusion — A method of diffusing air in an aeration
  tank of the activated sludge process where, by means of properly de-
  signed baffles and the proper location of diffusers, a spiral or heli-
  cal movement is given to the air and the tank liquor.

spiral-flow aeration — A method of diffusing air in an aeration tank
  of the activated sludge process,  See spiral air-flow diffusion.

spiral-flow tank — An aeration tank or channel in which a spiral or
  helicoidal motion is given to the liquid in its flow through the tank
  by the introduction of air through a line of diffusers placed en one
  side of the bottom of each channel, by longitudinally revolving pad-
  dles, or by other means.

spray  irrigation — A method for disposing of some organic wastewaters
  by  spraying them on land, usually from pipes equipped with spray
  nozzles.  This has proved to be an effective way to dispose of wastes
  from the canning, meat-packing, and sulfite-pulp industries where
  suitable land is available.

stabilization —  (l) Maintenance at a relatively nonfluctuating level,
  quantity, flow, or condition.  (2) In lime-soda water softening, any
  process that will minimize or eliminate scale-forming tendencies.
   (3)  In waste treatment, a process used to equalize wastewater flow
  composition prior to regulated discharge.

stabilization lagoon — A shallow pond for storage of wastewater before
  discharge.  Such lagoons may serve only to detain and equalize waste-
  water  composition before regulated discharge to a stream, but often
  they are used for biological oxidation.  See stabilization pond.

 stabilization pond — A type of oxidation pond in which biological

                               Glossary  U2

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                                                            EM  1110-2-501
                                                             Part  1  of  3
                                                              29 Sep 78

   oxidation of organic matter  is  affected by  natural  or  artificially ac-
   celerated transfer  of  oxygen to the vater from  air.

 step aeration  —  A procedure for  adding  increments  of settled  -waste-
   water  along  the line of  flow in the aeration tanks  of  an  acti-
   vated  sludge plant.

 sterilization  —  The  destruction  of  all  living microorganisms,  as  patho-
   genic  or  saprophytic bacteria,  vegetative forms,  and spores.

 sterilized  wastewater — An effluent from a wastewater treatment plant
   in which  all microorganisms  have been  destroyed by  sterilization.

 subsoil  —  That portion of a normal  soil profile underlying the surface.
   In humid  climates it is  lower in content of organic matter,  lighter
   in color,  usually of finer particles,  of denser, structure, and of
   lower  fertility than the surface soil.  Its depth and physical prop-
   erties control  to a considerable degree the movement of soil mois-
   ture.  In  arid  climates there is less  difference between surface and
   subsoil.

 sump —  (l)  A  tank or pit that receives  drainage and  stores it tempo-
   rarily, and  from which the drainage is pumped or ejected.  (2) A
   tank or pit  that receives liquids,

 supernatant  — The liquid standing above a sediment or precipitate,

 surface evaporation — Evaporation from the surface of a body of water,
   moist soil,  snow, or ice.  Also  see evapotranspiration.

 sui-face wash — (l) A supplementary method of washing the filtering
  medium of a rapid sand filter by applying water under pressure at or
  near the surface of the sand by means of a system of stationary or
  rotating jets.  (2) The surface runoff draining into a ditch or drain.

 suspended solids — Solids that either float  on the surface of, or
  are in suspension in,  water,  wastewater,  or other liquids, and which
  are largely removable  by laboratory filtering.

tank — Any artificial receptacle through which liquids pass or in
  which they are held in reserve or detained  for any purpose.

temperature — (l) The thermal  state of a substance with respect to its
  ability to communicate  heat to its environment.   (2) The  measure of
  the thermal state on some arbitrarily chosen numerical scale.


                               Glossary  ^3

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Part 1 of 3

29 Sep 78
tertiary treatment — A method used to refine the effluents from sec-
  ondary treatment systems or otherwise increase the removal of
  pollutants.

thickened sludge — A sludge concentrated to a higher solids content by
  gentle mixing, gravimetric settling, centrifugation, or air flotation.

thickener, sludge — A type of sedimentation tank in which sludge is
  permitted to settle, usually equipped with scrapers traveling along
  or around the bottom of the tank to push the settled sludge to a
  sump.

thickening tank — A sedimentation tank for concentrated suspensions.

total Kjeldahl nitrogen — The sum of free ammonia and of organic com-
  pounds which are converted to (NH, ) SO,  under the conditions of
  digestion.

total organic carbon (TOG) — A measure of the amount of organic mate-
  rial in a water sample expressed in milligrams of carbon per liter of
  solution.

toxin — Poisonous compounds produced by the metabolic activity or
  death and disintegration of microorganisms.

trash — Floating debris that may be removed from reservoirs, combined
  sewers, and storm-water sewers by coarse racks.

trash rack — A grid or screen placed across a waterway to catch float-
  ing debris.

trash screen — A screen installed or constructed in a waterway to col-
  lect and prevent the passage of trash.

treated  sewage — Wastewater that has received partial or complete
  treatment .

treatment — See following terms modifying treatment :  anaerobic waste ,
  biological wastewater, chemical, intermediate, ion-exchange , prelim-
  inary , primary , secondary wastewater, sludge , waste, wastewater , water.

trickling filter — A treatment unit consisting of a material such as
  broken stone, clinkers, slate, slats, or brush, over which  sewage  is
  distributed and applied in drops, films, or  spray, from troughs,
  drippers, moving distributors, or fixed nozzles, and through which
                               Glossary

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                                                           EM 1110-2-501
                                                             Part 1 of 3

                                                               29 Sep  78
  it trickles to the underdrains, giving opportunity for the formation
  of zoological slimes which clarify and oxidize the sewage.

trickling filter humus — The sludge removed from clarifiers following
  biological stabilization in trickling filter units.

trickling filter ponding — A condition occurring when voids in filter
  media become clogged with excessive growth of organisms, preventing
  the free flow of the wastewater.

trickling-filter process — In wastewater treatment, a process in which
  the liquid from a primary clarifier is distributed on a bed of stones.
  As the wastewater trickles through to drains underneath, it comes
  in contact with slime on the stones, by which organic material in
  the water is oxidized and impurities are reduced.

turbidity — (l) A condition in water or wastewater  caused by the pres-
  ence of suspended matter, resulting in the scattering and absorption
  of light rays.  (2) A measure of fine suspended matter in liquids.
  (3) An analytical quantity usually reported in arbitrary turbidity
  units determined by measurements of light diffraction.

ultraviolet radiation — Light waves shorter than visible blue-violet
  waves of the spectrum, having wave lengths of less than 3,900 A.

ultraviolet rays — Those invisible light rays beyond the violet of the
  spectrum.

underdrain — A drain that carries away groundwater  or the drainage
  from prepared beds to which water or wastewater has been applied.

underflow — (l) The movement of water through a given cross section
  of permeable rock or earth, possibly under the bed of a stream or a
  structure.  (2) The flow of water under a structure.

undigested sludge — Settled sludge promptly removed from sedimentation
  tanks before decomposition has much advanced.   Also called raw sludge.

vacuum filter — A filter consisting of a cylindrical drum mounted on
  a horizontal axis, covered with a filter cloth, and revolving with
  a partial submergence in liquid.  A vacuum is maintained under the
  cloth for the larger part of a revolution to extract  moisture.   The
  cake is scraped off continuously.

velocity — See settling velocity.

                               Glossary 45

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EM 1110-2-501
Part 1 of 3
29 Sep 78

viscosity — The cohesive force existing "between particles of a fluid
  which causes the fluid to offer resistance to a relative sliding
  motion between particles.

volatile — Capable of being evaporated at relatively low temperatures.

volatile solids — The quantity of solids in water, wastewater, or other
  liquids, lost on ignition of the dry solids at 600°C.

wash water — Water used to wash filter beds in a rapid sand filter.

wash-water gutter — A trough or gutter used to carry away the water
  that has washed the sand in a rapid sand filter.  Also called wash-
  water trough.

wash-water rate — The rate at which wash water is applied to a rapid
  sand filter during the washing process.  Usually expressed as the.
  rise of water in the filter in inches per minute or gallons per min-
  ute per square foot.

waste — Something that is superfluous or rejected; something that can
  no longer be used for its originally intended purpose.

wasted sludge — The portion of settled solids from the final clarifier
  that was removed from the wastewater treatment processes and trans-
  ferred to the solids handling facilities for ultimate disposal.

waste(s) — See following terms modifying waste(s):  industrial,
  municipal.

waste treatment — Any process to which wastewater or industrial waste
  is subjected to make it suitable for subsequent use.

waste water — In a legal sense, water that is not needed or that  has
  been used and is permitted to escape, or that unavoidably escapes
  from ditches, canals, or other conduits, or reservoirs  of the lawful
  owners of such structures.   See wastewater.

wastewater — The spent water of a community.  From the  standpoint of
  source, it may be a combination of the liquid and water-carried
  wastes from residences, commercial buildings, industrial plants, and
  institutions, together with any ground-water, surface  water, and storm
  water that may be present.   Also referred to as sewage.

wastewater decomposition — Transformations of organic  or inorganic

                               Glossary h6

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                                                           EM 1110-2-501
                                                             Part  1  of  3
                                                              29 Sep  78

  materials contained in waste-water through the action of chemical or
  biological processes.   Also see decomposition of wastewater.

waste-water disposal — The act of disposing of wastewater by any method
  (not synonymous with wastewater treatment).   Common methods of disposal
  are:  dispersion, dilution, broad irrigation, privy, cesspool.

wastewater facilities — The structures, equipment, and processes
  required to collect, carry away, and treat domestic and industrial
  wastes, and dispose of the effluent.

wastewater lagoon — An impoundment into which wastewater is discharged
  at a rate low enough to permit oxidation to occur without substantial
  nuisance.

wastewater treatment — Any process to which wastewater is subjected in
  order to remove or alter its objectional constituents and thus render
  it less offensive or dangerous.  See intermediate treatment, primary
  treatment.

wastewater treatment works — (l) An arrangement of devices and struc-
  tures for treating wastewater, industrial wastes, and sludge.  Some-
  times used as synonymous with waste treatment plant or wastewater
  treatment plant.  (2) A water pollution control plant.

water — A transparent, odorless, tasteless liquid, a compound of  hydro-
  gen and oxygen, H20, freezing at 32°F or 0°C and boiling at 212°F  or
  100°C, which, in more or less impure state, constitutes rain, oceans,
  lakes, rivers, and other such bodies; it contains 11.188 percent
  hydrogen and 88.812 percent oxygen, by weight.  It may exist as  a
  solid, liquid, or gas and, as normally found in the lithosphere, hy-
  drosphere, and atmosphere, may have other solid, gaseous, or liquid
  materials in solution or suspension.

water-borne disease — A disease caused by organisms or toxic substances
  carried by water, the most common of which diseases are typhoid fever,
  Asiatic cholera, dysentery, and other intestinal disturbances.

water closet — A plumbing fixture, usually a toilet bowl, seat,  and
  water tank, or valved pressure water connection, for carrying off
  excreta and liquid wastes to a drain pipe connected below, by the
  agency of flushing water.

water conditioning — Treatments, exclusive of disinfection,  intended


                               Glossary ^7

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EM 1110-2-501
Part 1 of ^
29 Sep 78

  to produce a water free of taste, odor, and other undesirable
  qualities.

water treatment — The filtration or conditioning of water to render it
  acceptable for a specific use.

water treatment plant — That portion of water treatment works intended
  specifically for water treatment; may include, among other operations,
  sedimentation, chemical coagulation, filtration, and chlorination.
  See water treatment works.

water treatment works — A group or assemblage of processes, devices,
  and structures used for the treatment or conditioning of water.

weir — (1) A diversion dam.  (2) A device that has a crest and some
  side containment of known geometric shape,  such as a V, trapezoid,  or
  rectangle, and is used to measure flow of liquid.  The liquid surface
  is exposed to the atmosphere.   Flow is related to upstream height of
  water above the crest, to position of crest with respect to down-
  stream water surface, and to geometry of the weir opening.

weir loading — In a solids-contact or sedimentation unit, the rate in
  gallons per minute per foot of weir length  at which clarified or
  treated liquid is leaving the  unit.   Also see overflow rate.

wet well — A compartment in which a liquid is collected, and to which
  the suction pipe of a pump is  connected.

zooglea — A jelly-like matrix developed by bacteria, associated with
  growths in oxidizing beds.

zoogleal matrix — The floe formed primarily  by slime-producing bacteria
  in the activated sludge process or in biological beds.
                               Glossary k8

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                                                           EM 1110-2-501
                                                             Part 1 of 3

                                                              29 Sep 78
                                  INDEX
                                                 _Faragraph       Page

Activated sludge (See Biological unit processes
  and Cost data and economic analysis)
Adsorption (See Chemical unit processes and Cost
  data and economic analysis)
Aeration (See Biological unit processes and Cost
  data and economic analysis)
Ammonia (See Chemical unit processes and Cost
  data and economic analysis)
Backwashing (See Filtration and Microscreening)
Biological unit processes:
    Activated sludge:
        Complete mix:
            Background	    7-19          7-37
            Bibliography	    7_26          7-66
            Cost data	    7-25          7-66
            Design  parameters  	    7-21          7-39
            Design  procedure:
                Eckenfelder's approach ....    7-22b          7-48
                McKinney's approach	    7-22a          7-40
            Example calculations
              (Eckenf elder)    	    7-24          7-57
            Input data	    7-20          7-37
            Output  data	    7-23          7-56
        Contact  stabilization:
            Background	    7-51          7-151
            Bibliography	    7.58          7-168
            Cost data	    7.57          7-168
           Design  parameters	   '7-53          7-153
           Design  procedure	    7-54          7-154
           Example calculations  	    7-56          7-l6l
           Input data	    7-52          7-151
           Output  data	    7-55           7-l60
       Extended aeration:
           Background	    7-35           7-95
           Bibliography	   7_l+2           7-125
           Cost data	   7-4l           7-124
           Design parameters   	   7-37           7-96
           Design procedure:
               Eckenfelder's approach ....   7-38b          7-105
               McKinney's approach  	   7-38a          7-98


                                Index 1

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EM 1110-2-501
Part 1 of 3
29 Sep 78
                                                  Paragraph       Page
            Example calculations
              (Eckenf elder)	    7,-hO          7-115
            Input data	    7-36          7-95
            Output data	    7-39          7-llU
        Modified or high-rate:
            Background	    7-^3          7-129
            Bibliography	    7-50          7-1^7
            Cost data	    7-^9          7-1^-7
            Design parameters   	    7-^5          7-130
            Design procedure  (Eckenfelder)  .  .    J-h6          7-131
            Example calculations 	    7-U8          7-lUo
            Input data	    7-U4          7-129
            Output data	    7-^7          7-138
        Plug flow:
            Background	    7-10          7-13
            Bibliography	    7-l8          7-3)1
            Cost data	    7-17          7-3^
            Example calculations 	    7-l6          7-25
            Design parameters   	    7-13          7-15
            Design procedure  (Eckenfelder)  .  .    7-Ik          7-17
            Input data	    7-12          7-lU
            Output data	    7-15          7-2^
        Pure oxygen:
            Background .....  	    7-59          7-171
            Bibliography	    7-66          7-200
            Cost data	    7-65          7-200
            Design parameters   	    7-6l          7-172
            Design procedure:
                Eckenfelder's approach  ....    7-62b          7-182
                McKinney's approach   	    7-62a          7-17U
            Example calculations	  .    7-6U          7-191
            Input data	    7-bO          7-171
            Output  data	    7-63          7-190
        Step aeration:
            Background 	  .....    7-27          7-69
            Bibliography .	    7-34          7-90
            Cost data	    7-33          7-90
            Design parameters	    7-29          7-71
            Design procedure:
                Eckenfelder's approach  ....    7-30b          7-8l
                McKinney's approach   .....    7-30a          7-72
            Example calculations  	    7-32          7-90


                                 Index  2

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                                                       EM 1110-2-501
                                                         Part 1 of 3
                                                           29 Sep 78

                                              Paragraph       Page

        Input data	    7-28          7-69
        Output data	    7-31          7-89
Digestion:
    Aerobic:
        Background 	    7-100         7-278
        Bibliography 	    7-107         7-287
        Cost  data	    7-106         7-287
        Design parameters  	    7-102         7-278
        Design procedure 	    7-103         7-278
        Example calculations 	    7-105         7-283
        Input data	    7-101         7-278
        Introduction	    7-99          7-277
        Output data	    7-104         7-282
    Anaerobic:
        Background 	    7-108         7-291
        Bibliography 	    7-115         7-304
        Cost  data	    7-111)         7-304
        Design parameters  	   "7-110         7-29^
        Design procedure 	    7-111         7-294
        Example calculations 	    7-113         7-298
        Input data	    7-109         7-293
        Output data	    7-112         7-298
Lagoons:
    Aearated  aerobic:
        Background	    7-67          7-205
        Bibliography	    1-lk          7-221
        Cost  data	    7-73          7-221
        Design parameters:
           Eckenfelder's approach ....    7-69b         7-206
           McKinney's approach  	    7-69a         7-206
        Example calculations
          (Eckenf elder)    	    7-72          7-216
        Input data	    7-68          7-205
        Output data	    7-71          7-215
    Aerated facultative:
        Background	    7-75          7-223
        Bibliography	    7-82          7-233
        Cost  data	    7-8l          7-232
        Design parameters  	    7-77          7-223
        Design procedure	    7-78          7-224
        Example calculations 	    7-80          7-228
        Input data	    7-76          7-223


                             Index 3

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                                                  Paragraph       Page

            Output data	    7-79          7-227
    litrification-denitrification:
        Background	    7-91          7-253
        Bibliography	    7.98          7-27^
        Cost data	    7-97          7-271!
        Design parameters	    7-93          7-255
        Design procedure	    7-9^          7-255
        Example calculations 	    7-96          7-267
        Input data	    7-92          7-25*1
        Output data	    7-95          7-266
    Oxidation ditch:
        Background	    7-83          7-235
        Bibliography	    7-90          7-251
        Cost data	    7-89          7-251
        Design parameters  	    7-85          7-236
        Example calculations (Eckenfelder) .  .    7-88          7-2^4
        Input data	    7-84          7-235
        Output data	    7-87          7-2^3
    Stabilization ponds:
        Background 	    7-ll6         7-307
        Bibliography 	    7-123         7-313
        Cost data	    7-122         7-313
        Design parameters  	    7-118         7-309
        Design procedure 	    7-119         7-309
        Example calculations 	    7-121         7-311
        Input data	    7-117         7-308
        Output data	    7-120         7-310
    Trickling filters:
        Background	    7-2           7-3
        Bibliography	    7-9           7-9
        Cost data	    7-8           7-9
        Design parameters  	    7-^           7-5
        Design procedures  	    7-5           7-5
        Example calculations 	    7-7           7-7
        Input data	'	    7-3           7-3
        Output data	    7-6           7-7
Centrifugation (See Cost data and economic
  analysis and Physical unit processes)
Centrifuge (See Centrifugation)
Chemical coagulation (See Chemical unit
  processes and Cost data and economic
  analysis)

                                 Index H

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                                                  Paragraph	     Page

Chemical unit processes:
    Ammonia stripping:
        Background	    6-l8          6-25
        Bibliography	    6-25          6-32
        Cost data	    6-24          6-32
        Design parameters  	    6-20          6-27
        Design procedure	    6-21          6-27
        Example calculations 	    6-23          6-30
        Input data	    6-19          6-27
        Output data	    6-22          6-30
    Carbon adsorption:
        Background	    6-2            6-3
        Bibliography	    6-9            6-14
        Cost data	    6-8            6-14
        Design parameters  	    6-4            6-5
        Design procedure	    6-5            6-5
        Example calculations 	    6-7            6-9
        Input data	    6-3            6-4
        Output data	    6-6            6-9
    Chemical coagulation:
        Background	    6-10          6-17
        Bibliography	    6-17          6-22
        Cost data	    6-l6          6-22
        Design parameters   	    6-12          6-l8
        Design procedure	    6-13          6-l8
        Example calculations 	    6-15          6-20
        Input data	    6-11          6-18
        Output data	    6-14          6-19
    Chlorination:
        Background	    6-26          6-35
        Bibliography	    6-33          6-41
        Cost  data	    6-32           6-41
        Design parameters   	    6-28           6-36
        Design procedure	    6-29           6-36
        Example calculations  	    6-31           6-38
        Input  data	    6-27           6-35
        Output  data	    6-30           6-38
    Ion  exchange:
        Background	    6-34           6-43
        Bibliography	    6-41           6-53
        Cost  data	    6-40           6-53
        Design  parameters   	    6-36           6-43


                                Index 5

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                                                  Paragraph       Page

        Design procedure	   6-37           6-1*1*
        Example calculations 	   6-39           6-U8
        Input data	   6-35           6-1*3
        Output data	   6-38           6-1*7
    Neutralization:
        Background	   6-1*2           6-55
        Bibliography	   6-57           6-67
        Cost data	   6-56           6-67
        Design parameters   	   6-52           6-62
        Design procedure	   6-53           6-62
        Example calculations 	   6-55           6-65
        Input data	   6-51           6-62
        Output data	   6-5!*           6-61*
    Recarbonaiiion:
        Background	   6-50           6-6l
        Bibliography	   6-57           6-67
        Cost data	   6-56           6-67
        Design parameters   	   6-52           6-62
        Design procedure	   6-53           6-62
        Example calculations 	   6-55           6-65
        Input data	   6-51           6-62
        Output data	   6-5^           6-61*
    Two-stage lime  treatment:
        Background	   6-58           6-69
        Bibliography	   6-66           6-91
        Chemical coagulation 	   6-59           6-69
        Cost data	   6-65           6-90
        Example calculations	   6-61*           6-83
        Output data	   6-63           6-8l
        Primary clarifier   	   6-60;6-62     6-72;6-78
        Recarbonation	   6-6l           6-76
 Chlorination  (See  Chemical unit  processes and
   Cost  data and economic analysis)
 Chlorine  (See Chlorination)
 Clarification  (See  Cost data and economic
   analysis  and Physical unit processes)
 Clarifiers  (See Clarification  and'
   Sedimentation)
 Comminution (See  Cost data and economic
   analysis  and Physical unit processes)
                                  Index 6

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                                                           EM 1110-2-501
                                                             Part 1 of 3
                                                              29 Sep 78
                                                  Paragraph
Complete mix activated sludge (See Biological
  unit processes and Cost data and economic
  analysis)
Contact stabilization activated sludge (See
  Biological unit processes and Cost data
  and economic analysis)
Cost data and economic analysis:
    Biological unit processes:
        Activated Sludge:
            Complete mix	    8-30
            Contact stabilization  	    8-34
            Extended aeration  	    8-32
            Modified or high-rate aeration .  .    8-33
            Plug flow	    8-29
            Pure oxygen	    8-35
            Step aeration	    8-31
        Digestion:
            Aerobic	    8-40
            Anaerobic	    8-4l
        Lagoons, aerated:
            Aerobic	    8-36
            Facultative	    8-37
        Nitrification-denitrification   ....    8-39
        Oxidation ditch  	    8-38
        Stabilization ponds	    8-1*2
        Trickling filters   	    8-28
    Chemical unit processes:
        Ammonia stripping   	    8-22
        Carbon adsorption   	    8-20
        Chemical coagulation  	    8-21
        Chlorination  	    8-23
        Ion  exchange	    8-24
        Neutralization  	    8-25
        Recarbonation  	    8-26
        Two-stage lime  treatment  	    8-27
    Physical unit processes:
        Cascade  aeration  	    8-l6
        Centrifugation  	    8-12
        Comminution	    8-4
        Drying beds	    8-l4
        Equalization  	    8-5
        Filtration    	    8-10
    Page
 8-18
 8-19
 8-18
 8-19
 8-17
 8-20
 8-18

 8-23
 8-24

 8-20
 8-20
 8-21
 8-21
 8-24
 8-17

 8-14
 8-13
 8-13
 8-l4
 8-15
 8-15
 8-15
 8-15

 8-12
 8-10
 8-6
8-11
8-6
8-9
                                Index 7

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                                                  Paragraph       Page

        Flotation	   8-6           ^
        Grit removal	   8-2           8-5
        Incineration:
            Fluidized bed	   8-19          8-12
            Multiple-hearth	   8-l8          8-12
                                                 o -i o          $ "i n
        Microscreening  	   o-±j          p
        Postaeration	   8-15          8-11
        Screening	   8-3           8-5
        Sedimentation:
            Primary clarifier   	   8-8           8-8
            Secondary clarifier   	   8-9           8-8
        Sludge  hauling  and  land  filling   .  .  .   8-17          8-12
        Thickening (gravity)  	   8-7           8-7
        Vacuum  infiltration  	   8-11          8-9
 Denitrification (See Biological  unit processes
   and Cost  data and  economic  analysis)
 Digestion (See  Biological unit processes  and
   Cost data and economic analysis)
 Drying beds (See Cost data  and  economic
   analysis  and  Physical unit  processes)
 Equalization (See Cost  data and economic
   analysis  and  Physical unit  processes)
 Filter (See Filtration)
 Filtration  (See Cost data  and economic
   analysis  and  Physical unit processes)
 Floe (See Sedimentation)
 Flotation (See  Cost  data  and economic
   analysis and Physical unit processes)
 Grit (See Cost  data and economic analysis and
   Physical xmit processes)
 Lagoons  (See Biological unit processes and
   Cost data and economic  analysis)
 Microscreening  (See Cost  data and economic
   analysis and Physical unit processes)
 Microscreens (See Microscreening)
 neutralization  (See Chemical unit processes and
   Cost data and economic analysis)
 Nitrification  (See Biological unit processes
   and  Cost data arid economic analysis)
 Physical unit processes:
      Centrif-ugation:
          Background	   5-o4

                                   Index 8

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                                                        EM 1110-2-501
                                                          Part 1 of 3
                                                           29 Sep  78
                                               Paragraph
Page
     Bibliography	    5-91          5-137
     Cost  data	    5-90          5-136
     Design parameters   	    5-86          5-133
     Example calculations  	    5-89          5-135
     Design procedure	    5-87          5-131
     Input data	    5-85          5-133
     Output data	    5-88          5-13^
 Comminution:
     Background	    5_l8          5-29
     Bibliography	    5-25          5-31
     Cost  data	    5-2U          5-31
     Design parameters   	    5-20          5-29
     Design procedure	    5-21          5-29
     Example calculations  	    5-23          5-31
     Input data	    5-19          5-29
     Output data	    5-22          5-29
 Drying Beds:
     Area  required in Northern U. S.   ...    Table  5-27     5-157
     Background  	    5-100          5-1^9
     Bibliography  	    5-107          5-156
     Cost  data	    5-106          5-155
     Design parameters	    5-102          5-1^9
     Design procedure 	    5-103          5-151
     Example calculations  	    5-105          5-153
     Input data	    5-101          5-1^9
     Output data	    5-101*          5-153
 Equalization:
     Background	    5-26          5-33
     Bibliography	    5-33           5-39
     Cost  data	    5-32           5-39
    Design parameters	    5-28           5-3^
    Design procedure	    5-29           5-3^
    Example calculations  	    5-31           5-36
    Input data	    5-27           5-33
    Output data	    5-30           5-36
Filtration:
    Background	    5-68           5-93
    Bibliography	    5-75           5-113
    Cost data	    5-7^           5-113
    Design parameters   	    5-70           5-97
    Design procedure	    5-71           5-98
    Example calculations  	    5-73           5-105
                             Index 9

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                                                  Paragraph       Page
Input data 	
Output data 	
Flotation:
Background 	
Bib-tiography 	
Cost data 	 	 	
Design parameters . 	
Design procedure 	
Exariple calculations 	
Input data ..... 	

Grit removal:
Background.
Chairber 	 	
Aerated 	





y. terete settling 	
Horizontal flow 	


Particle size 	
Settling velocities 	

L;ibL:ic(-:r-a.ph;y 	
Cost ua~ca 	

Design procedure 	
Example calculations 	 .
Input data ....... 	
Output data 	
Incineration:
Fluid! zed bed:
Background 	 	 .
5-69
5-72

5-34
5-41
5-1*0
5-36
5-37
5-39
5-35
5-38


5-2a,c,d
5-2d
5-2g
Figure 5-1
Table 5-2
5-2a,b,e
5-2f,g
5-2c
5-2d
5-2g
Figure 5-2
5-2b,c
5-2c
Table 5-1
5-9
5-8
5-4
5-5
5-7
5-3
5-6


5-129
5-96
5-105

5_Ui
5-53
5-53
5-42
5-42
5-47
5-^1
5-47


5-3
5-3
5-4
5-5
5-18
5-3-1*
5-4
5-3
5-3
5-4
5-5
5-3
5-3
5-18
5-16
5-16
5-4
5-6
5-11
5-4
5-10


5-189
            Bibliography  	   5-136         5-209
            Cost data	   5-135         5-209
            Design parameters   	   5-131         5-193
            Design procedure 	   5-132         5-194
            Example calculations  	   5-134         5-200
                                Index 10

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                                                         EM  1110-2-501
                                                          Part  1  of  3
                                                            29 Sep 78

                                               Paragraph       Page

         Input data	3-130         5-192
         Output data	   5-133         5-199
     Multiple-hearth:
         Background 	   5-121         5-177
         Bibliography 	   5-128         5-186
         Cost data	   5-127         5-185
         Design parameters  	   5-123         5-177
         Design procedure	   5-121*         5-179
         Example calculations 	   5-126         5-182
         Input data	   5-122         5-177
         Output data	   5_125         5-l8l
 Microscreening:
     Bibliography	   5.99          5-146
     Cost data	   5.98          5-146
     Definition 	   5-92a         5-139
     Design parameters	   5-9^          t;--lU•
     Design procedure	   5.95          5-141
     Example calculations 	   5-97          5-l!3
     Input  data	   5-9^          5-141
     Output data	   5-06          5-1^
 Postaeration:
     Background 	   5-108         5-159
     Cascade aeration  	   5-110         5-lb5
         Design parameters   	   5-110b         5-165
         Design procedure 	   5-110c         5-l66
         Example  calculations  	   5-110e         5-167
         Input  data	    5-110a         5-165
         Output data	    5-11 Of!         5-167
    Mechanical or diffused  aeration   .  .  .    5-109         5-159
    Bibliography	  .    5-112         5-l68
    Cost data	    5_111         5_l68
Screening:
    Background	    5_10          5-19
    Bibliography	    5-17          5-25
    Cost data	    5-l6          5-25
    Design parameters  	    5-12          5-21
    Design procedure	    5-13          5-21
    Example calculations 	    5-15           5-23
    Input data	    5-11           5-20
    Output data	    5-14           5-23
Sedimentation:
    Primary clarifier:


                            Index 11

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                                                  Paragraph __     Page

            Background	   5-52          5-68
            Bibliography	   5-59          5-80
            Categories	   5-51          5-6?
            Cost data	   5-58          5-80
            Definition	   5-50          5-6?
            Design parameters   	   5-54          5-70
            Design procedure	   5-55          5-70
            Example calculations  	   5-57          5-76
            Input data	   5-53          5-68
            Output data	   5-56          5-75
            Sedimentation tank	   Figure  5-8    5-69
        Secondary clarifier:
            Background	   5-60          5-83
            Bibliography	   5-67          5-90
            Cost data	   5-66          5-90
            Design parameters   	   5-62          5-84
            Design procedure	   5-63          ^~«
            Example calculations  	   5-65          5-87
            Input data	   5-6l          5-83
            Output data	   5-64          5-86
            Settling tanks  	   Table 5-11   5-91
     Sludge hauling and landfilling:
         Background  	   5-113         5-169
         Bibliography  	   5-120         5-17^
         Cost  data	   5-119         5-174
         Design parameters	    5-H5         5-171
         Design procedure 	    5-Ho         5-171
         Example calculations	    5-H8         5-173
         Input data	    5-114         5-170
         Output data	    5-H7         5-172
     Thickening (gravity):
         Background	    5-42            (•
         Bibliography	    5-49          5-63
         Cost data	    5-U8          5-63
         Design parameters  	    5-44          5-59
         Design procedure 	    5-45            ^
         Example calculations 	    5-47          5-63
         Input data	    5-43          5-59
         Output data	    5-46          5-63
     Vacuum filtration:
         Average chemical doses for  	    Table  5-19    5-129
         Background	    5-76          5-119

                                  Index 12

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                                                            EM 1110-2-501
                                                              Part 1 of 3
                                                                29 Sep 78
         Bibliography 	
         Centrifuge performance 	
         Cost data  .  .  	
         Design parameters  	
         Design procedure 	
         Example calculations 	
         Expected performance 	
         Input data 	
         Output data  	
         Polyelectrolyte doses  for  	
 Plug flow activated sludge  (See Biological
   unit processes and Cost data and
   analysis)
 Polyelectrolytes (See Physical unit processes)
 Screening (See Cost data and economic
   analysis and Physical unit processes)
 Screens (See Screening)
 Sedimentation (See Cost  data and economic
   analysis and Physical  unit processes)
 Sludge (See  Biological unit  processes and
   Cost data  and economic  analysis)
 Step aeration (See Biological  unit processes
   and Cost data and economic analysis)
 Thickeners (See Thickening)
 Thickening (See Cost  data and  economic
   analysis and Physical unit processes)
 Trickling filters  (See Biological unit
   processes and Cost  data and  economic
   analysis)
Urban  Studies  Program:
    Area planning:
        Duplication of effort   	
        Responsibility 	 . 	
        Leadership  	
Vacuum filtration  (See Cost  data and economic
  analysis and Physical unit processes)
Waste:
    Flow:
        Average  	
        Calculations 	
        Domestic 	
  Paragraph

 5-83
 Table 5-23
 5-82
 5-78
 5-79
 5-81
 Table 5-22
 5-77
 5-80
 Table 5-20
l-ltb(l)
2-2a,b
2-2a(2)
Table 2-2
3-2c
                                                                   Page
 5-127
 5-138
 5-127
 5-121
 5-121
 5-130
 5-121
 5-129
1-1
1-1
1-1
2-1
2-1
2-3
3-2
                                Index 13

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                                                   Paragraph       Page

        Factors affecting reading   	    2-2a(l)        2-1
        Maximum reading	    2-2b           2-2
        Minimum reading	    2-2b           2-2
        Peak reading	    2-2b           2-2
        Residential   	    Table  2-1     2-3
Wastewater:
    Composition	    1-Ud           1-2
    Infiltration	    2-2c           2-2
    Inflow	    2-2c           2-2
    Quality	    2-3           2-2
    Systems:
        Bibliography	    U-5           U-3
        Design criteria	    1-1           1-1
        Design equations and practices  ....    U-3a-g        U-l
        Design factors	    3-1           3-1
        Economic  analysis	    U-U           U-3
        Phases of design	    3-2           3-2
        Physical  unit processes   	    5-la-q        5-1
        Planning	    U-5a,b        k-3
        Problems  of design  	    l-5a-g        1-2
        Selection of	    1-1           1-1
                                                  3-lb(l)-(l2)  3-1
                                                  3-2d           3-2
        Site selection 	    3-la(l)-(l2)  3-1
Wastewater treatment:
    Process selection  	    U-la-g        U-l
    Process substitution diagram 	    U-2           U-l
Water consumption, average  	    2-2a,b        2-1
                                 Index Ik
                                            *U.S. GOVERSMENT PRINTING OFFICE : 1979 0-620-007/3776

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        C"  -"'
O
o

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