United States
Environmental Protection
Agency
Office of Water
Program Operations (WH-547)
Washington DC 20460
March 1978
EPA 430/9-77-011
Water
&EPA
Energy Conservation
in Municipal
Wastewater Treatment
MCD-32
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EPA REVIEW NOTICE
This report has been reviewed by the Environmental
Protection Agency, and approved for publication.
Approval does not signify that the contents necessarily
reflect the views and policies of the Environmental
Protection Agency, nor does mention of trade names or
commercial products constitute endorsement or recom-
mendation for use.
DISTRIBUTION
Single copies of this report are available to the
public by submitting a written request to:
General Services Administration (8FFS)
Centralized Mailing Lists Services
Building 41, Denver Federal Center
Denver, Colorado 80225
Please indicate the title of the publication and the
MCD number.
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EPA - 430/9-77-011
TECHNICAL REPORT
ENERGY CONSERVATION
IN MUNICIPAL WASTEWATER
TREATMENT
BY
George M. Wesner
Gordon L. Gulp
Thomas S. Li neck
Daniel J. Hinrichs
Contract No. 6.8-03-2186, Task 9
Project Officers
Malcolm Simmons
Francis L. Evans. Ill
March, 1978
Prepared for
Environmental Protection Agency
Office of Water Program Operations
Washington, D.C. 20460
MCD-32
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TABLE OF CONTENTS
CHAPTER
CHAPTER
CHAPTER
CHAPTER
LIST OF ABBREVIATIONS
CHAPTER 1 - INTRODUCTION
PURPOSE AND APPLICATION
BACKGROUND
LIMITATIONS
2 - NATIONAL ENERGY REQUIREMENTS
3 - PRIMARY ENERGY REQUIREMENTS
4 - SECONDARY ENERGY REQUIREMENTS
5 - IN-PLANT ENERGY RECOVERY AND RECYCLING
INTRODUCTION
«sy
HEATING REQUIREMENTS IN WASTEWATER TREATMENT PLANTS
UTILIZATION OF ANAEROBIC DIGESTER GAS
INCINERATION
PYROLYSIS
INCINERATION VERSUS PYROLYSIS
HEAT TREATMENT OF WASTEWATER SLUDGES
HEAT PUMPS
SOLAR ENERGY USE IN WASTEWATER TREATMENT PLANTS
CHAPTER
W«LIp VT WASTEWATE« TREATMENT
t-ACILITIES - INVOLVING NO CAPITAL OUTLAYS
6 - EXAMPLES - ENERGY REQUIREMENTS, RECOVERY AND RECYCLING
EXAMPLE 1 - TRICKLING FILTER (ROCK MEDIA) WITH
COARSE FILTRATION
Page
1-1
1-1
1-2
1-3
2-1
3-1
4-1
5-1
5-1
5-2
5-16
5-38
5-52
5-65
5-66
5-74
5-78
5-94
6-1
6-1
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TABLE OF CONTENTS ( CONTINUED)
EXAMPLE 2
EXAMPLE 3
EXAMPLE 4
EXAMPLE 5
EXAMPLE 6
EXAMPLE 7
EXAMPLh
EXAMPLE 8
EXWPLE 9
ACTIVATED SLUDGE WITHOUT INCINERATION
ACTIVATED SLUDGE WITH INCINERATION
EXTENDED AERATION
EXTENDED AERATION WITH SLOW SAND FILTER
ACTIVATED SLUDGE WITH CHEMICAL
CLARIFICATION
ACTIVATED SLUDGE WITH NITRIFICATION
m CLARIFICATION
- ACTIVATED SLUDGE - HIGHER THAN
SECONDARY TREATMENT
10 -
EXAMPLE 11 - PONDS
EXAMPLE 12 - LAND TREATMENT BY INFILTRATION/
PERCOLATION
EXAMPLE 13 - LAND TREATMENT BY OVERLAND FLOW
EXAMPLE 14 -
EXAMPLE
TREATMENT BY SOLID SET OR
IRRIGATIQN
CHAPTER 7 - ENERGY REQUIREMENTS FOR TREATMENT FACILITIES GREATER
CHAPTER 7 ^100 jjGD AND LESS THAN 1 MGD
TREATMENT FACILITY CAPACITY LESS THAN 1 MGD
TREATMENT FACILITIES WITH CAPACITIES GREATER THAN
100 MGD
CHAPTER 8 - NATIONAL AND REGIONAL COST PROJECTIONS
INTRODUCTION
NATIONAL COST PROJECTIONS
REGIONAL COST VARIATIONS
CHAPTER 9 - ENERGY EFFECTIVENESS AND COST EFFECTIVENESS
6-3
6-3
6-4
6-5
6-5
6-5
6-5
6-6
6-6
6-6
6-6
6-7
6-7
7-1
7-1
7-1
8-1
8-1
8-2
8-5
9-1
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TABLE OF CONTENTS (CONTINUED)
INTRODUCTION
EXAMPLE 1 - SECONDARY TREATMENT
EXAMPLE 2 - HIGHER THAN SECONDARY TREATMENT
EXAMPLE 3 - HIGHER THAN SECONDARY TREATMENT
CHAPTER 10 -ENERGY IMPLICATIONS OF SEPARATE AND COMBINED
SEWERS AND INFILTRATION/INFLOW
INTRODUCTION
SWIRL CONCENTRATOR
SCREENS
AIR FLOTATION
HIGH RATE FILTRATION
FLOW EQUALIZATION
CHLORINATION
9-1
9-2
9-4
9-5
10-1
10-1
10-3
10-3
10-4
10-5
10-5
10-6
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LIST OF ABBREVIATIONS AND SYMBOLS
NH,/NH,,
average
'"' «VB
Baume .
Be
bed volume(s)
BV
biochemical oxygen demand ..
' BOD
British thermal unit .
Btu
calcium hydroxide (hydrated lime)
Ca(OH)2
calcium oxide (quick lime)
CaO
carbon dioxide ..
C02
chemical oxygen demand
COD
chlorine
C12
coefficient of performance ...
COP
cubic foot (feet)
" cu ft
cubic feet per minute
cfn
cubic yard
cu yd
degree(s)
deg
degree Celsius
°C
degree Fahrenheit ...
"F
diameter
diara
feet (foot)
feet per second
-- fps
ferric chloride
Fed,
flow rate
Q
food to microorganisms ratio
gallon(s)
gal
gallons per day
gpd
gallons per day per square foot .
gpd/sq ft
gallons per minute ...
- gpm
gallons per minute per square foot
gpm/sq ft
horsepower
hp
horsepower hour(s) ..
hp-hr
hour(s) ....
hr
hydrogen sulfide
H2S
Inch(es)
In.
Independent physical-chemical .
internal coniustion
Jackson turbidity unit
.........-..---.....................w.__Bs- jfu
kilogram(s)
kg
kilowatt ..
kw
kilowatt hour
... ...... .................. fcwh
mercury
«g
methanol
CH3OH
mlcron(s)
Ji
miles per gallon
mpfl
miles per hour
mph
per liter .
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List of Abbreviations and Symbols (Continued)
......... mro
millimeter
mil
million
mil gal
million gallons
million gallons per day mg
min
minute(s)
mixed liquor suspended solids
Ml VSS
mixed liquor volatile suspended solids
. MPN
most probable number
N03
nitrate
N
nitrogen *
02
oxygen
J
percent
P
phosphorus
, , lb
pound(s)
psf
pounds per square foot
. . ,. ps1
pounds per square Inch
pounds per square 1nch absolute
. . psig
pounds per square inch gage "
POTW
publicly owned treatment works
NaOH
sodium hydroxide "
SRT
solids retention time
sq ft
square foot (feet)
suspended solids
standard cubic foot (feet)
scfm
standard cubic feet per minute
S02
sulfur dioxide
H2SOi,
sulfuric acid
AT
temperature change ;
.... TDS
total dissolved solids '
TDH
total dynamic head
TS
total solids
VF
vacuum filter
G
velocity gradient
VS
volatile solids
WAS
waste activated sludge
wt
weight
yr
year(s) "
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CHAPTER 1
INTRODUCTION
PURPOSE AND APPLICATION
This technical report provides information for primary and some secondary
energy use and primary energy conservation in the EPA municipal wastewater
treatment construction grants program. Primary energy is the energy used
in the operation of a facility, such as the electricity used in the various
processes and space heating. Secondary energy for the purposes of this
report is defined as the energy required to manufacture chemicals and other
consumable materials used in municipal wastewater treatment. Secondary
energy requirements for treatment plant construction materials, such as
concrete and steel, were not determined in this study. In addition to
identifying energy utilization and conservation for a wide range of treat-
ment alternatives available to meet the standards, the report will aid in
screening alternatives for their energy reduction potential. The report
should be useful to municipalities, since municipal operations including
energy costs are financed by user charges.
The report is being distributed to those that have policy and decision
authority impacting the design, construction, and operation of wastewater
treatment plants. This will include personnel in the EPA regional offices,
state and local government employees, and design consultants involved in
the planning and design activities of the EPA's Construction Grants Program.
This publication is not intended as a design manual but as an effective
means for making preliminary energy comparisons based upon the assumptions
set forth in this report. Process energy utilization and conservation
should be of particular value throughout the planning project formulation,
and preliminary engineering process.
1-1
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BACKGROUND
Incorporation of low energy consumption concepts in municipal wastewater
treatment facilities designs is a factor in the grants review process.
The "Grants Regulations and Procedures, Revision of Part 40 CFR 30.420-6"
(Federal Register, May 8, 1975) provides that:
"Grantees must participate in the National Energy Conservation
Program by fostering, promoting and achieving energy conservation
in^their grant programs. Grantees must utili^ to the f
practical extent the most energy-efficient equipment, materials,
and construction and operating procedures available.
"Guidance for Preparing a Facility Plan" (EPA Office of Water Program Opera-
tions, May 1975 revision) requires in Part 4.2.2.e that "energy production
and consumption" in the planning area should be described to the extent
necessary to analyze alternatives and determine the environmental impacts
of the proposed actions. Primary and secondary energy curves contained
in this report should be useful in fulfilling this requirement for facility
planning.
The economics of low energy utilization are contained in the "Cost-
Effectiveness Analysis Guidelines" 40 CFR Part 35, Appendix A .(Federal
Register, September 10, 1973). For waste management systems, a cost-
effective solution is one which will minimize total resource costs to
the nation over time to meet National Pollutant Discharge Elimination
System permit requirements based on best practicable waste treatment
technology including Federally approved state water quality standards.
Resource costs include capital (construction and land acquisition); opera-
tion, maintenance, and replacement; and social and environmental costs.
Energy utilization and conservation will impact all of these resource costs.
Comparative cost information which may be useful to the reader for integrat-
ing cost and energy effectiveness may be obtained from the technical report,
"A Guide to the Selection of Cost-Effective Wastewater Treatment Systems,"
1-2
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(EPA-430/9-75-002, July 1975) in conjunction with its supplement, "An
Analysis of Construction Cost Experience for Wastewater Treatment Plants,"
(EPA-430/9-76-002, MCD-22, February 1976). Cost information on land
treatment systems may be obtained from "Costs of Wastewater Treatment
by Land Application," (EPA-430/9-75-003, June 1975) and "Cost-Effective
Comparison of Land Application and Advanced Wastewater Treatment" (EPA-
430/9-75-016, MCD-17, November 1975).
Information contained in this report must be used in grant application with-
in the framework of cost-effectiveness. Systems used in the design of new
treatment facilities or upgrading of existing facilities which also promote
energy conservation are eligible for grant funding provided that they are
cost-effective. Two situations arise, however, where grant awards presently
are not eligible. First, the modification of existing municipal facilites
So1e1y for tne purpose of energy conservation is not grant eligible. Second,
in the situation of multi-purpose projects such as co-incineration of sludge
and solid waste, non-program components (e.g., solid waste) of the project
are not eligible for funding despite the fact that the overall project might
result in energy conservation. Cost allocation for multi-purpose projects
is contained in the Municipal Construction Division Program Requirements
Memorandum, "Cost Allocations for Multi-Purpose Projects." The preferred
cost allocation method for multi-purpose projects is the "alternative
justifiable expenditure" method, which is explained in "The Allocation of
Costs of Federal Water Resource Development Projects," a report to the House
Committee of Public Works from the Subcommittee to Study Civil Works, 82nd
Congress, December 2, 1952.
LIMITATIONS
A basic limitation of this document is the integration of cost-effectiveness
and energy effectiveness (discussed in Chapter 8). Theoretically, the two
should be similar, but for a variety of reasons this may not be the case.
1-3
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For instance, the regional fuel price structure is variable and will reflect
the relative availability of a particular type of energy, such as fuel oil,
natural gas, coal, or nuclear. Thus, a particular treatment train might be
energy as well as cost-effective in one region, while only energy effective
in another. Similarly, while the energy effectiveness of a particular pro-
cess might be high, the cost-effectiveness might not reflect this fact if
the system is labor intensive and labor costs are high for a particular pro-
ject. For this reason, the current regional cost variations for various
cost categories that affect treatment plant construction and operation are
presented in Chapter 8. The importance of regional cost category varia-
bility in integrating energy and cost curves cannot be overstressed.
It is expected that the energy data presented in this report will be re-
vised and updated periodically. This is necessary since waste treatment
processes are modified in light of more effective energy utilization and
as new energy effective techniques and methodologies are developed. As
more experience is gained in practice with the existing and newer advanced
wastewater treatment and sludge handling processes, more energy data will
become available for analysis.
The reader should realize that the circumstances of a particular situation
may alter the energy effectiveness data presented. For example, the in-
fluence of very cold weather would likely eliminate from consideration a
highly temperature dependent process such as ammonia stripping and could
change the energy effectiveness for other systems such as activated sludge
and trickling filters. Similarly, if the percentage of industrial waste-
water or inflow and infiltration is high or if the composition of the
waste stream differs markedly from the "typical" influent wastewater
quality assumed herein, modifications must be made in choosing energy
effective systems. Adjustments will also be necessary should any of the
design criteria shown on the process curves be changed.
1-4
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This report attempts to ascertain all the primary energy needs of waste-
water treatment processes. For secondary energy, the report provides
estimates for the manufacture and transportation of the consumables used
in wastewater treatment. No attempt, however, is made to estimate the
energy required to manufacture the materials used in the construction of
treatment plants.
1-5
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CHAPTER 2
NATIONAL ENERGY REQUIREMENTS
The purpose of this chapter is to compare the energy required for
various processes utilized in publicly owned treatment works (POTW's)
with total national energy requirements. Data collected by EPA during
the 1976 Needs Survey for publicly owned wastewater treatment facilities
indicated that 13,220 POTW's are required to provide treatment for the
sewered population of 158,573,000 in 1977 and 19,041 POTW's are required
to provide treatment for the sewered population of 258,411,000 in 1990.
Present (1977) and future (1990) energy utilization have both been
estimated by integrating the data from the 1976 Needs Survey for treatment
facilities with process energy utilization data in Chapter 3. Table 2-1
shows the national energy requirements for 1977 and 1990 for various
processes of municipal wastewater treatment. The averages used for the
different plant capacity ranges are as follows: <5 mgd, 1 mgd was used;
5 mgd < 10 mgd, 7.5 mgd was used; 10 mgd < -20 mgd, 15 mgd was used; 20 mgd <
50 mgd, 35 mgd was used; > 50 mgd, 75 mgd was used. The energy require-
ments per million gallons were then multiplied times the average capacity
and number of plants to calculate the energy requirements for the
various levels of treatment. Energy requirements for sludge treatment
and disposal are included in the estimates. Energy requirements for
treatment of storm flows in combined sewer systems are excluded from the
estimates. It .was assumed in these estimates that 40 percent of the
activated sludge and trickling filter plants would dispose of sludge by
incineration, ,30 percent by landfill and 30 percent by land application.
The energy requirements include all primary and secondary energy (except
secondary energy required for construction materials) for complete
wastewater treatment and sludge disposal. Because these treatment
operations require both electrical energy and fuel, a breakdown is shown
in Table 2-1 for various levels of treatment. Also, the total energy
requirements (Btu/yr) are shown for various levels of treatment by
assuming that electricity generation requires 10,500 Btu/kwh. The 1976
Needs Survey shows that 32 percent of municipal facilities have secondary
treatment and it is estimated for this report that 100 percent will
2-1
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attain this level as a minimum by 1990. The 1976 Needs Survey also
shows that 0.5 percent of municipalities are now employing nitrification, :
and 4 percent expect to do so in the future. Similarly, 6 percent of
municipal plants now have filtration, and 26 percent expect to in the
future.
Based on projected effluents from the 1976 Needs Survey, approxi-
mately 200 advanced waste treatment (AWT) facilities requiring low
discharge levels of BOD (< 5mg/l), suspended solids (< 5 mg/1), phosphorus
(< 1 mg/1 as P) and nitrogen (< 5 mg/1 total N) will be constructed by
1990. The average flow of these facilities was approximately 15 mgd.
In order to include these facilities in the projected energy needs, a
plant consisting of secondary treatment, with separate phases for
nitrification, chemical clarification and filtration and an average flow
of 15 mgd was included in Table 2-1. Use of filtration and nitrification
will, in many cases, be employed in these AWT facilities. As a result,
some duplication in these processes occurs in Table 2-1. However, since
the impact of these processes is small, the total energy requirements
are not largely affected by this duplication.
For 1977, 142.87 x 1012 Btu/yr of energy use is expected, which
represents 0.17 percent of the total national energy use in 1977; for ;
1990, 256.91 x 1012 Btu energy use is expected, which represents 0.23
percent of the total national use in 1990. (See "The Cost of Air and
Water Pollution Control - 1976 thru 1985," EPA report to Congress, April
1977 Draft.) Table 2-2 presents national energy utilization estimates :
for present (1977) and future (1990) treatment facilities based on
information from the 1976 Needs Survey applied to information contained
in Table 2-1.
2-2
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TABLE 2-1(a)
National Energy Requirements For Various Processes
of Municipal Wastewater Treatment
SOURCE: 1976 NEEDS SURVEY FOR MUNICIPAL WASTEWATER TREATMENT
1977
PLANT TYPE OF
CAPACITY TREATMENT
MGD
Less than T.F.*
4.99 A.S.
Filt.
Nitr.
Ponds
5 to 9.99 T.F.
A.S.
Filt.
Nitr.
Ponds
10 to 19.99 T.F.
A.S.
Filt.
Nitr.
Ponds
AWT
20 to 49,99 T.F.
A.S.
Filt.
Nitr.
Ponds
50 and over T.F.
A.S.
Filt.
Nitr.
Ponds
SECONDARY
TERTIARY
rp^rp A -r
TOTAL
NUMBER
OF PLANTS
1951
6925
471
17
3397
121
274
36
4
59
58
161
16
5
27
__
34
116
9
5
16
6
70
3
1
5
13,220
SECONDARY
TERTIARY
KWH/YR
108
8.33
34.99
0.14
0.03
11.42
2.60
7.24
0.09
0.05
1.40
2.43
8.49
0.08
0.11
1.91
2.91
13.28
0.11
0.24
1.87
0.98
16.70
0.06
0.11
1.21
115.76
1.02
116.78
BTU/YR " '
1012
3.70
5.82
-0-
-0-
-0-
0.60
1.33
-0-
-0-
-0-
0.57
1.59
-0-
-0-
-0-
0.73
2.50
-0-
-0-
-0-
0.26
3.15
-0-
-0-
-0-
20.25
20.25
141.80
1.07
TOTAL
*T.F. = Trickling Filter
A.S. = Activated Sludge
Filt. = Filtration
Nitr. = Nitrification
AWT = Advanced Waste Treatment
**Assumes generation of 1 kwh requires 10,500 BTU fuel
2-3
142.87 x 1012 BTU/YR**
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TABLE 2-1(b) :
National Energy Requirements For Various Processes
of Municipal Wastewater Treatment
SOURCE: 1976 NEEDS SURVEY FOR MUNICIPAL WASTEWATER TREATMENT
PLANT TYPE OF
CAPACITY TREATMENT
MGD
Less than
1*.99
5 to 9-99
10 to 19-99
20 to 1*9.99
50 and over
TOTAL
T.F.*
A.S.
Filt.
Nitr.
Ponds
T.F.
A.S.
Filt.
Nitr.
Ponds
T.F.
A.S.
Filt.
Nitr.
Ponds
AWT
T.F.
A.S.
Filt.
Nitr.
Ponds
T.F.
A.S.
Filt.
Nitr.
Ponds
SECONDARY
TERTIARY
NUMBER
OF PLANTS
2021*
9399
1*51*3
1*33
6092
137
505
213
78
89
62
282
109
39
36
200
1*1
215
81*
33
21
8
123
1*3
15
7
19,oUl
KWH/YR
108
8, .61*
1*7 ..1*9
1.38
0.65
20.1*9
2.9l*
13.31*
0.53
0.89
2.11
2.60
lU.87
0.52
0.88
2.5!*
21.10*
3.51
24.61
1.08
1.59
2.45
1.31
29.33
0.81*
1.6U
1.70
177.93
31.10
209.03
BTU/YR
1012
3.83
7.90
-0-
-0-
-0-
0.68
2.50
-0-
-0-
. -0-
0.61
2.78
-0-
-0-
-0-
7.71*
0.88
4.63
-0-
-0-
-0-
0.31*
5.53
-0-
-0-
-0-
29.68
7.7!*
37-1*2
SECONDARY
TERTIARY
TOTAL
216.51
1*0.1*0
256.91 x 1012 BTU/YR**
*If land treatment systems replaced the 200 AWT plants, the annual
electrical power would "be reduced from 21.1 x 108 KWH/YR to
1*.28 x 108 KWH/YR or a savings of 79$- Since solids would not be
incinerated with land treatment, the BTU requirement would be 0.
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TABLE 2-2
1977 and 1990 Estimated Energy Consumption
In Publicly Owned Treatment Works
1977
TOTAL
1990
TREATMENT
PROCESS
Secondary
Tertiary
TOTAL
ENERGY
101 BTU/YR
141.80
1.07
^PERCENT OF 1977
NATIONAL ENERGY
UTILIZATION
0.17
***
TOTAL
ENERGY
10 BTU/YR
216.51
40.40
**PERCENT OF 1990
NATIONAL ENERGY
UTILIZATION
0.23
ftft*
142.87
0.17
256.91
0.23
^Assumes 1977 National Energy use is 86 x 1015 Btu/yr
**Assumes 1990 National Energy Use is 114 x 1015 Btu/yr
(See "The cost of Air and water pollution control - 1976 thru 1985 "
EPA Report to Congress, April 1977 Draft.
***Less than 0.01 Percent
2-5
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CHAPTER 3
PRIMARY ENERGY REQUIREMENTS
Primary energy requirements are presented in graphical form in Figures 3-1
through 3-118 for the municipal wastewater treatment process listed in Table
3-1. The design and operating conditions, expected influent and effluent
quality and assumptions used in the determination of energy requirements
are shown on the figures. The examples in Chapters 6 and 9 illustrate the
use of these figures. The assumed quality of raw wastewater used in de-
scribing the unit processes is shown in Table 3-2 and assumed untreated
sludge characteristics for various processes are shown in Table 3-3.
The oxygen transfer efficiency shown on the relevant biological treatment
curves is "wire to water" efficiency which includes the efficiency of motors
and mechanical equipment. Several of the curves are based on laboratory or
pilot scale data and it is so noted below the title on these figures.
3-1
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TABLE 3-1
PRIMARY ENERGY REQUIREMENTS - UNIT PROCESSES
UNIT PROCESS
FIGURE NO.
PUMPING
Raw Sewage Pumping (Constant Speed)
Raw Sewage Pumping (Variable Speed)
Raw Sewage Pumping (Variable Speed)
Lime Sludge Pumping
Alum Sludge Pumping
Ferric Chloride Sludge Pumping
PRELIMINARY TREATMENT
Mechanically Cleaned Screens
Comminutors
Grit Removal (Aerated)
Grit Removal (Non-Aerated)
Pre-Aeration
SEDIMENTATION
Primary Sedimentation
Secondary Sedimentation
Chemical Treatment Sedimentation
Chemical Treatment Sedimentation
BIOLOGICAL TREATMENT
TDH 5 to 30 Feet
TDH 60 to 100 Feet
Alum or Ferric Chloride
Lime
High Rate Trickling Filter (Rock Media)
Low Rate Trickling Filter (Rock Media)
High Rate Trickling Filter (Plastic Media)
Super-High Rate Trickling Filter (Plastic Media)
Rotating Biological Disk
Activated Biofilter
Brush Aeration (Oxidation Ditch)
Oxygen Activated Sludge - Open Top Reactor - Fine
Bubble Diffusion
Oxygen Activated Sludge - Covered Reactor (Cryogenic)
3-1
3-2
3-3
3-4
3-5
3-6
3-7
3-8
3-9
3-10
3-11
3-12
3-13
3-14
3-15
3-16
3-17
3-18
3-19
3-20
3-21
3-22
3-23
3-24
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TABLE 3-1 (continued)
Oxygen Activated Sludge - Covered Reactor (PSA)
Activated Sludge - Coarse Bubble Diffusion
Activated Sludge - Fine Bubble Diffusion
Activated Sludge - Mechanical Aeration
Activated Sludge - Turbine Sparger
Activated Sludge - Static Mixer
Activated Sludge - Jet Diffuser
Aerated Ponds
BIOLOGICAL NITRIFICATION/DENITRIFICATION
Nitrification - Suspended Growth
Nitrification - Fixed Film Reactor
Denitrification - Suspended Growth (Overall)
Denitrification - Suspended Growth Reactor
Denitrification - Aerated Stabilization Reactor
Denitrification - Sedimentation and Sludge Recycle
Denitrification - Fixed Film, Pressure
Denitrification - Fixed Film, Gravity
Denitrification - Fixed Film, Upflow
Single Stage Carbonaceous/Nitrification/ and Denitrification
- Without Methanol Addition, Two Stage Pulsed Air
Single Stage Carbonaceous/Nitrification and Denitrification
- Without Methanol Addition, Multi-Stage
Single Stage Carbonaceous/Nitrification/ and Denitrification
- Without Methanol Additional - Orbital Plants
CHEMICAL FEEDING
.Lime Feeding
Alum Feeding
Ferric Chloride Feeding
Sulfuric Acid Feeding
CHEMICAL CLARIFICATION
Solids Contact Clarification - High Lime, Two Stage Recarbona-
tion
Solids Contact Clarification - High Lime With Sulfuric Acid
Neutralization
Solids Contact Clarification - Single Stage Low Lime With
Sulfuric Acid Neutralization
3-25
3-26
3-27
3-28
3-29
3-30
3-31
3-32
3-33
3-34
3-35
3-36
3-37
3-38
3-39
3-40
3-41
3-42
3-43
3-44
3-45
3-46
3-47
3-48
3-49
3-50
3-51
-------
TABLE 3-1 (Continued)
Solids Contact Clarification - Alum or Ferric Chloride Addition
Reactor Clarifier
Separate Rapid Mixing, Flocculation, Sedimentation - High Lime,
Two Stage Recarbonation
Separate Rapid Mixing, Flocculation, Sedimentation - Single
Stage High Lime, Neutralization With Sulfunc Acid
Separate Rapid Mixing, Flocculation, Sedimentation - Low Lime,
Neutralization With Sulfuric Acid
Separate Rapid Mixing, Flocculation, Sedimentation - Alum
or Ferric Chloride Addition
Rapid Mixing
Flocculation
Recarbonation - Solution Feed of Liquid C02 Source
Recarbonation - Stack Gas As C02 Source
MICROSCREENS
Microscreens
FILTRATION
Pressure and Gravity Filtration
ACTIVATED CARBON TREATMENT
Granular Carbon Adsorption - Downflow Pressurized Contactor
Granular Carbon Adsorption - Downflow Gravity Contactor
Granular Carbon Adsorption - Upflow Expanded Bed
Granular Activated Carbon Regeneration
AMMONIA REMOVAL
Ion Exchange for Ammonia Removal
Ion Exchange for Ammonia Removal
Ion Exchange for Ammonia Removal
Air Stripping
Ion Exchange for Ammonia Removal
Steam Stripping
Ammonia Stripping
Breakpoint Chlorination with Dechlorination
DISINFECTION
Chlorination and Dechlorination
Chlorine Dioxide Generation and Feeding
Ozone Disinfection
- Gravity and Pressure
- Regeneration
- Regenerant Renewal By
- Regenerant Renewal By
3-52
3-53
3-54
3-55
3-56
3-57
3-58
3-59
3-60
3-61
3-62
3-63
3-64
3-65
3-66
3-67
3-68
3-69
3-70
3-71
3-72
3-73
3-74
3-75
3-76
-------
TABLE 3-1 (Continued)
DjEMINERALIZATION
Ion Exchange For Demineralization, Gravity and Pressure
Reverse Osmosis
LAND TREATMENT
Land Treatment by Spray Irrigation
Land Treatment by Ridge and Furrow Irrigation and Flooding
Infiltration/Percolation and Overland Flow by Flooding
Infiltration/Percolation and Overland Flow by Solid
Set Sprinklers
BUILDING HEATING AND COOLING
Wastewater Treatment Plant Building Heating Requirements
Wastewater Treatment Plant Building Cooling Requirements
SLUDGE THICKENING
Gravity Thickening
Air Flotation Thickening
Basket Centrifuge
SLUDGE CONDITIONING
Elutriation
Heat Treatment (Electrical Energy)
Heat Treatment - Without Air Addition (Fuel)
Heat Treatment - With Air Addition (Fuel) Curve 1
Heat Treatment - With Air Addition (Fuel) Curve 2
Chemical Addition (Digested Sludges)
Chemical Addition (Undigested Sludges)
SLUDGE DEWATERING
Vacuum Filtration
Filter Pressing
Centrifuging
Sand Drying Beds
SLUDGE DISPOSAL
Sludge Pumping
Dewatered Sludge Haul by Truck
Liquid Sludge Hauling by Barge
3-77
3-78
3-79
3-80
3-81
3-82
3-83
3-84
3-85
3-86
3-87
3-88
3-89
3-90
3-91
3-92
3-93
3-94
3-95
3-96
3-97
3-98
3-99
3-100
3-101
-------
TABLE 3-1 (Continued)
Liquid Sludge Hauling By Truck
Utilization of Liquid Sludge
Utilization of Dewatered Sludge
SLUDGE STABILIZATION
Anaerobic Digestion - High Rate
Thermophilic Anaerobic Digestion
Aerobic Digestion
Thermophilic Aerobic Digestion
Chlorine Stabilization of Sludge
Lime Stabilization of Sludges
SLUDGE CONVERSION
Multiple Hearth Furnace Incineration - Fuel Required
Multiple Hearth Furnace Incineration - Start-up Fuel
Multiple Hearth Furnace Incineration - Electrical Energy Required
Fluidized Bed Incineration - Fuel Required
Fluidized Bed Furnace Incineration - Electrical Energy Required
Sludge Drying
Wet Air Oxidation
LIME RECALCINATION
Lime Recalcining - Multiple Hearth Furance
3-102
3-103
3-104
3-105
3-106
3-107
3-108
3-109
3-110
3-111
3-112
3-113
3-114
3-115
3-116
3-117
3-118
-------
TABLE 3-2
RAW WASTEWATER CHARACTERISTICS
Parameter
Biochemical Oxygen Demand
Suspended Solids
Phosphorus, as P
Total Kjeldahl Nitrogen, as N
Nitrite plus Nitrate
Alkalinity, as CaC03
PH
Concentration
19/1, except pH
210
230
11
30
0
300
7.3
-------
TABLE 3-3
SLUDGE CHARACTERISTICS
Total
Solids
Sludge (wt percent
Type of sludae)
Primary
Primary
+ FeC13
Primary +
Low Lime
Primary +
High Lime
Primary +
WAS
Primary +
(WAS+FeCl3)
(Primary+FeClJ
+ WAS J
WAS
WAS+FeClo
o
Digested
Primary
Digested
Primary+WAS
Digested
Primary + WAS
* FeC13
Tertiary Alum
Tertiary
High Lime
Terti ary
Low Lime
5
2
5
7.5
2
1.5
1.8
1.0
1.0
8.0
4.0
4.0
1.0
4.5
3.0
Sludge Solids
(Ib/mil gal)
Total Volatile
Solids Solids
1151
2510
4979
9807
2096
2685
3144
945
1535
806
1226
1817
700
8139
3311
690
1176
2243
4370
1446
1443
1676
756
776
345
I
576
599
242
3219
1301
Volatile
Solids Sludge
(wt percent Volume
nf total solids) (qal/mil gal)
60
47
45
45
69
54
53
80
50
43
47
33
35
40
39
2,760
16,500
11,940
15,680
12,565
21,480
20,960
11,330
18,400
1,210
3,680
5,455
8,390
21,690
13,235
-------
10,000,000
1,000,000
Q
tu
O!
0 100,000
Ul
Q!
O
Q!
Ill
Ul
U
UJ
ui 10,000,
1,000
FLOW, mgd
RAW SEWAGE PUMPING (CONSTANT SPEED)
Design Assumptions:
Efficiencies for typlcol centrifugal pumps (varies with flow)
Variable level wet well
TDH is total dynamic head
Type of Energy Required: Electrical
FIGURE 3-1
-------
10.000,000
1,000
FLOW, mgd
RAW SEWAGE PUMPING (VARIABLE SPEED)
( Curve 1 of 2)
Design Assumptions:
Efficiencies for typicol centrifugal pumps (varies with flaw)
Wound Rotor variable speed
Variable level wet well
Type of Emrgy Required: Electrical
FIGURE 3-2
-------
100,000,000
I
J
cT
ui
tt
u
DC
o
CK
UI
10,000,000
1
1,000,000
8
6
5
4
3
z
100,000
7
6
s
4
3
z
10,000
..,/
/ ,
/
/
/
J .
~J? ~
j
...
X
:'/
* s
/
- -
^^
/
~^ ^
_^fc
r
.X
//
/x
/ '
-4--
_ .. _
-j/
X
f
^r~ ~~y
£
/
-
- TT TDH
' ^TDH
S! 3 <» S6789 2 34 56789 2 34 5678" 2
o-1 i.o 10 100
= 1
= 61
3
T~ t~-
i
00 ft 1
ift
₯
__
456 789
1,000
FLOW, mgd
RAW SEWAGE PUMPING (VARIABLE SPEED)
(Curve 2 of 2)
Design Assumptions:
Efficiencies for typical centrifugal pumps (varies with flow)
Wound rotor variable speed
Variable level wet well
Type of Energy Required: Electrical
FIGURE 3-3
-------
O.T
1,000
PLANT CAPACITY, mgd
SECONDARY EFFLUENT, HIGH LIME
10
100
I
SECONDARY EFFLUEINT, LOW LIME
*
100
RAW SEWAGE, HIGH LIME
RAW SEWAGE, LOW LIME
1 10
100
3 4 5 67 89
10
3 456789
100
3456 789
1,000
VOLUME OF SLUDGE PUMPED, gpm
LIME SLUDGE PUMPING
Design Assumptions:
TDH 25 ft ~_
Operating Parameters:
Sludge concentrations, secondary treatment, are 5% for low lime and
7.5% for high lime
Sludge concentrations, tertiary treatment, are 3i% for low lime and
4.5% for high lime
Type of Energy Required: Electrical
FIGURE 3-4
-------
PLANT CAPACITY, mgd ( secondary effluent)
[P 100 IQOO
J
a*
ui
ee
i
UI
Of
o
<£.
UI
u
K
U
UI
10,000,000
1,000,000
100,000
1
t
10,000
I
6
5
4
3
2
1,000
X
1
-ri
PL;
_x
^NT
10
air
U ^e
CAPACI1
Y, mgd ( raw
S
r
_
sewa
100
-/_
ge)
/
1
y
/
/
ono
-^
TTT
10
100
2 3456 789
100,000
VOLUME OF SLUDGE PUMPED, 9pm
ALUM SLUDGE PUMPING
Water Quality: Influent Effluent
(Secondary) (mg/[) {mg/n
Suspended Solids 250 30
Phosphate as P 11.0 l.o
Design Assumptions:
TDH = 25 ft
Sludge concentration (secondary) = 1%
Sludge concentration (tertiary) ^ 0.5%
Operating Parameter:
Alum addition S 150 mg/l
Type of Energy Required: Electrical
Water Quality:
( Tertiary)
Suspended Solids
Phosphate as P
Influent Effluent
(mg/l) (mg/l)
30 10
11.0 1.0
FIGURE 3-5
-------
PLANT CAPACITY, mgd (secondary effluent)
0.1
1.0
10°
-t-
PLANT CAPACITY, mgd, (raw sowage)
1.0 T0
100
10,000,000
9
8
7
6
B
4
3
2
1,000,000
a
7
6
S
4
> 3
Q"
UI
§ 100,000
O 9
in «
> 6
OS 8
UI 4
Z
>" 3
is
5
b
j 10,000
UI
1,000
U.I
H r
-X
_ _ 1
---^
/
3 4 S 6789
1 10
s
Z 343
-^U l |
-U-U |
E=L
r
4-mJ ^--j-
^
, -
?\
.
^
/
ffl
578too 1,000 10,000
VOLUME SLUDGE PUMPED, gpm
FERRIC CHLORIDE SLUDGE PUMPING
Water Quality: Influent
(Secondary) (mg/l)
Suspended Solids 250
Phosphate as P 11.0
Effluent Water Quality:
(mg/l) (Tertiary)
30
1.0
Influent
(mg/l)
Suspended Solids 30
Phosphate as P 11.0
Efffuent
(mg/l)
10
1.0
Design Assumptions:
TDK - 25 ft.
Sludge concentration (secondary) m 2%
Sludge concentration (Tertiary) » 1%
Operating Parameters:
Ferric Chloride addition = 85 mg/l
Type of Energy Required: Electrical
FIGURE 3-6
-------
100,000
IU
100
0.1
1.0
10
FLOW, mgd
MECHANICALLY CLEANED SCREENS
Design Assumptions:
Normal run times are 10 mln total time per hr
except 0.1 mgd (Smln) and 100 mgd (15mln).
Bar Spacing Is % In
Worm gear drive, 50% efficiency
Type of Energy Required: Electrical
FIGURE 3-7
-------
S
I
a
I
oe
5
I
i
I
UJ
00
7
6
S
4
3
2
00
9
R
7
3
2
00
7
6
5
4
I
100
^^
0.1
-*1
2
3
^
4
^
Ml H
X-
,:^
x
^
5 6789 2 3 4 56789 2 a * oo'°*
FLOW/ mgd
COMMINUTORS
Type of Energy Required: Electrical
FIGURE 3-8
-------
10,000,000
1,000,000
o
111
at
5
ot
UI
UI
UI
UI
100,000
10,000
1,000
ft?ooo
3456 789
100,000
GRIT CHAMBER VOLUME, cu ft
GRIT REMOVAL (AERATED)
Water Quality:
Removal of 90% of material with a specific gravity of greater than 2.65
Design Assumptions:
Grit removed to a holding facility by a screw pump
Size based on a peaking factor of 2
Detention time is 3 min.
Tank design similar to that by Link-Belt, FMC Corp. or Jeffrey
Operating Parameters:
Air rate of 3 cfm per foot of length
Removal equipment
Type of Energy Required: Electrical
FIGURE 3-9
-------
100,000
o
Ul
o:
i
Ul
a.
tti
Ul
Ul
Ul
10,000
1,000
100
PLANT CAPACITY, m«d
10
10
-HH-rl'i'oo i i "**,«,* 4 567?oo 2 3 4 567?o9o,
GRIT CHAMBER VOLUME, cu ft
GRIT REMOVAL (NON-AERATED)
!roava|yof 90% of material with specific gravity greater than 2.65
OOO
Design Assumptions:
Grit removed to a holding facility by screw pump
Size based on peaking factor of 2
Square tank
Smallest volume is 117 cu ft
OP<"v0rrociry0oTo?S5r'fps though square tank or 1 min detention time a, average flow
Operate equipment 2 hr each day
Type of Energy Required: Electrical
FIGURE 3-10
-------
PLANT CAPACITY, mgd
10,000,000
1,000,000
J
cf
111
at
a
at
at
o
OS
ui
3
ae
U
u
100,000
10,000
1,000
100
3 456789
1,000
000
TANK VOLUME, cu ft
PRE - AERATION
Design Assumption:
Detention time is 20 min.
Operating Parameter:
Air supply is 0.15 cu ft /gal
Type of Energy Required: Electrical
FIGURE 3-11
-------
PLANT CAPACITY, mgd
1,000,000
100,000
O
til
CC
1
S
Ul
I
ui
10,000
1,000
RECTANGULAR TANKS
100
2 3 4 5 6789
1,000
2 3 4 5 6 789
10,000
2 3456 789
100,000
Water Quality:
BOD5
Suspended Solids
SURFACE A REA, sq ft
PRIMARY SEDIMENTATION
Influent Effluent
(mg/l) (mg/l)
210 136
230 80
Design Assumptions:
Sludge pumping Included
Scum pumped by sludge pumps
Multiple tanks
Operating Parameters:
Loading = tOOO gpd/sq ft
Waste rate = 65% of Influent solids, 5% concentration
Pumps operate 10 minutes of each hr
Type of Energy Required: Electrical
FIGURE 3-12
-------
PLANT CAPACITY, mgd
IU
at
a
ui
at
u
ui
10.000, 000 g
e
7
6
5
4
3
2
1,000,000
9
7
6
5
4
3
2
100,000
i
s
4
3
2
10,000
i
5
4
3
0.
1 *~
--^
1
1,000 I
'-
x^
4
r
1.
.
H ?
~7
/
\
100
- . ... s1
"
-------
PLANT CAPACITY, mgd
l,000,000g
8
6
8
4
s
2
100,000
a
v. 6
S
3
or
Ul
B:
£ 10,000
5 *
B! 3
S
Ul 2
Ul
V.OOO
1
100
1
0.1
1 1
00
2
MH iM ^
3 4 S £
1
.... -
7 89
1,000
^^«
^
. -
3 4 S <
10
- r
P B« i^^
"
5?i8o,9ooo
/
10
-/
/
100,000
0
~/~
r
4
4-5
-1
1,000,000
CLARIFIER SURFACE AREA, »q ft
CHEMICAL TREATMENT SEDIMENTATION
ALUM OR FERRIC CHLORIDE
D««lgn Auumptlons:
Coagulant: alum or ferric chloride
Operating Parameter:
Overflow rate « 700 gpd/«q ft
Type of Energy Required: Electrical
FIGURE 3-14
-------
PLANT CAPACITY, mgd
100,000
I
i
,l
8
t
RGY REQUIRED, kwh/yr
e
I * W Ol^lOXC ° ivj
ELECTRICAL ENE
^
"o
o
i
-------
PLANT CAPACITY, mg
10,000,000
8
6
s
4
3
2
1,000,000
i
6
S
^
I
a 2
0!
1 100,000
OC S
ELECTRICAL EKERGY
~*
f
»0 w w * .0 »-.
1,000
1
0.1
"
00
2
/
1.0
an *T
i
...y_
/
"7
/
s ' ="?>o " ' ' '
10
Af=
- ^~
/
/
/
1
/
,
r
T
>7i8,^oo 100,000 1,000,000
TRICKLING FILTER SURFACE! AREA, sq ft
HIGH RATE TRICKLING FILTER (ROCK MEDIA)
Water Quality:
BOD5
Suspended Solids
Influent
(mg/l)
136
80
Effluent
(ma/0
45
45
Dcilgn Assumption*: .
Hydraulic loading at, 0.4 gprn/sq. ft. including reCirCUlatlori
TDH » 10 ft
Ops-rating Parameter:
Reclreulatlon Ratio = 2 = 1
Typ* of Energy Required: Electrical
F1GJJRE 3-16
-------
PLANT CAPACITY, mgd
I
100,000,000
i
~l
6
5
10,000,000
£
7
6
4
2
1,000,000
1
e
I
9
4
3
2
100,000
§
7
g
3
3
2
10 000
0.
7-4-
....
X
1
/
--!--
I
_l_-
....
y
1
"*"
jf
"T
/'
1.0
-_.
...
-
...
/
-"
-1"
Pf
I
T
/^
i
1 J
H1
!
- ^Z
y'
,
f
10
ll . . r
..
T T' -' '
E
/
i p
i-
I
i
/
"
I
1
_x
.._
101
--\~
i
.....
-
/
....
2 3456789 23456789 2 3456789 2 34
1,000 10,000 100,000 1,000,000
)
-r-l-t-
_.--(_.
t~t"
IK
1 '"f"; {
*-K
K
\F\-^
£_
5
-
rH
4...
-f-
.
..
-}
r
^
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1
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10,000,000
TRICKLING FILTER SURFACE AREA, sq ft
LOW RATE TRICKLING FILTER (ROCK MEDIA)
Water Quality: Influent Effluent
(mg/l) (mg/l)
BOD5 136 30
Suspended Solids 80 30
Design Assumptions:
Hydraulic loading = 0.04 gpm/sq ft
TDH = 23 ft
Operating Parameter:
No recirculation
Type of Energy Required: Electrical
FIGURE 3-17
-------
PLANT CAPACITY, mgd
100,000,000
10,000,000
I
a*
s
g 1,000,000
S
oe
3
o;
u
UJ
ui 100,000
P
1
°
)
9
7
8
5
4
3
i.
)
9
9
4
I
)
;
u
*
0
I
6
5
4
n
0.1
' f
>
/
y
'
--
y
'
|
t
4-H
-/.
1.0
TF1 r
,.
i
t
i
4
.
/
_.
- - - ~ "
>
/
: '.:.
'---
-ri
/
s
TTT
+-.
i
i
1
T
i » .< '
|4
^
IT"
10
I
j
-4 -
1
*t
A
* ^L ,
- - -'
... . , .......
_. -j
/
., . ,,.
...
/
. _
/
!
"_V
100
L1..T. i
/
.. -...
- - '
;
/- +
... j
-j
...
Tp
r \
i
.. 4
1
15
|
-»+
i
i
100
2 3456789
1,000
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10,000
100,000
1,000,000
TRICKLING FILTER SURFACE AREA, sq ft
HIGH RATE TRICKLING FILTER (PLASTIC MEDIA)
Water Quality:
BODS
Suspended Solid*
Influent
(n.g/1)
136
80
Effluent
(mg/l)
35-45
35-45
Design Assumptions;
Hydraulic loading = 1.0 gpm/sq ft including recirculation
TDH = 40 ft
Operating Parameter:
Reclrculatlon Ratio =5:1
Type of Energy Required: Electrical
FIGURE 3-18
-------
0.1
PLANT CAPACITY, mgd
1.0
111
O£
>-
O
o:
IU
z
Ul
Of
O
111
IU
100,000,000
i
~i
6
5
10,000,000
c
e
7
6
4
X
i
a 2
u
£
y 1,000,000
"9
< I
7
> 6
£ 5
i
I 3
i
IdO.OOO
1
7
6
5
4
3
2
10,000
/
'
/'
-y^
f
/
/
/
/
~7
~/
s
/
IU
/
/
'
2 34 56789 2 34 56789 2 34 56789 2
10 100 1,000 10,000
~Y
s
3
_
4
10
I |_ i li
4-h
!
i
/X
3
f
56789
100,000
TRICKLING FILTER SURFACE AREA, sq ft.
SUPER - HIGH RATE TRICKLING FILTER ((PLASTIC MEDIA)
Water Quality:
BOD5
Suspended Solids
Influent Effluent
(mg/l) (mg/l)
136 82
80
48
Design Assumptions:
Hydraulic loading = 3 gpm/sq ft. including recirCUldtion
TDH = 40 ft
Operating Parameter:
Recirculation ratio = 2! I
Type of Energy Required: Electrical
FIGURE 3-19
-------
PLANT CAPACITY, mgd
a
ui
ce
i
UJ
DS
i
u
UJ
U
0,000,000
9
e
7
6
5
4
3
2
1,000,000
9
7
6
5
3
2
100,000
s
4
3
2
10,000
1
e
s
4
1,000
10,C
___^
/
00
/
z
3
=
!
/
4
... , _
A
' f
Q
_
3 STA
: -^
-^yf\
' /
NDAl
V-
.-_.
?D
ME
D1A
>
>
1.0
.. .
- -^
y /
? /
1. -DEN!
-
]
i
/
S
E Mi
/
x~
Dl.
[y
/J/
k
10
~f
' s
\ /
1 ..
" ~
-?T
-X
--
/
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~
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i
I
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*-f
1-
5669 3 4 56789 2 3 4 56789 Z 3 * o e r a =>
100,000 1,000,000 10,000,000 100,00
EFFECTIVE SURFACE! AREA, »q. ft
ROTATING BIOLOGICAL DISK
Influent
(tng/0
136
80
Effluent
(ing/I)
30
30
Water Quality:
BODg
Suspended Solid*
Design Assumptions:
Hydraulic loading = 1 gpd/ sq ft
Standard media = 100,000 sq, ft per unit
Dense media = 150,000 sq ft per unit
Type of Energy Required: Electrical
FIGURE 3-20
-------
PL ANT CAPACITY, mgd
ui
ae
a
IU
OL
o
OL
uj
u
u
IU
100,000,000
s
e
7
6
S
4
3
2
10,000,000
9
7
6
5
3
1,000,000
9
e
6
:
2
100,000
§
6
5 -
4 -
3 -
2 -
10,000 L
100
0
-.
_ . . .
>
.1
. - .4.
[ill
- -U
r r 1
I
- H
- ~
. ..
"- I
-.1 ._
_ r ... >
- V--
~
1,000
- -:_--
I
*
^
/
3456
i° .
I ' !
f ,[~ ~
r '
-! 4
-4-
I I
1
f yt
f'
1 ' "f
- ... -
7iofooo 2
..,-..
3
10
i a- . ,
I 1 '
L hr
- -1 4 -,
;-t-t-
I '' :
.. ,7|..f
1
/
/
/
--
.... . _.
4 5 blt
-. -- , L_
_ 4 }._..
;:^?
---- -
~ .-,,-.,
. .. ,
- ,_-,. .
)§,loo 2
"
?
Y-
3
t
'-
T
/
._.
....
4
100
Lit
i .
-t - +-
I/
X^ I
Hr-
H--
) 4- -i
*- !"
.
,
;
... , .
56l£
f *
-) \~-
' ' V
rjr^
U-
T"
i.
]r
....
_
_ .
0^0,000
BIO-CELL VOLUME, cu ft
ACTIVATED BIOFILTER
Water Quality:
Suspended Solids
Influent Effluent
20
20
80
Design Assumptions:
Bio-cell loading st 200 Ib BODs/1000 cu ft
Aeration = 1 Ib 02/lb BODs
Oxygen transfer efficiency in wastewater (mechanical aeration); 1.8 Ib 02/hp-hr
Operating Parameters:
Recirculation sr 0.9:1
Recycle sludge = 50%
Type of Energy Required: Electrical
FIGURE 3-21
-------
PLANT CAPACITY, m<|d
100,000,000
8
6
5
4
3
2
10,000,000
9
8
6
?GY REQUIRED, kwl
"o
§
"o
s
BIO M W *
Ul 7
Z 6
< 4
U
5 3
Ul 2
Ul
100,000
j
(
A
10,000
1
/
/
0.1
-TT
/
Y
/
i.
0
/
2 3456789 Z
DO MOO
^-
--
/
--
10
=tr
~7
f
t-
4
_^
/
,
100
-fe
J>
,\.
\
---
3 4 56Vo,9000 2 * 4 5VOO>0 * a " J W.OOO
OXYGEN REQUIREMENT, Ib/day
BRUSH AERATION (OXIDATION DITCH)
Influent
(mg/l)
136
80
Effluent
(mg/l)
20
20
Water Quality:
BOD5
Suspended Solids
Design Assumptions:
Oxygen transfer efficiency = 1.8 Ib Oj/hp-hr (wire to water)
,= 1.5 Ib 02consumed/lb BOD5 rernoved^4.6 Ib 02 consumed/lb
(In reactor foed) oxidized
Type of Energy Required: Electrical
FIGURE 3-22
-------
PLANT CAPACITY, mgd
UNSTAGED, PLUG FLOW OXYGEN ACTIVATED SLUDGE
1.0 10
COMPLETE MIX OXYGEN ACTIVATED SLUDGE
100
-H
100,000,001
10,000,00
1,000,000
8
4
3
2
100,000
7
s
4
s
2
10,000
p"
^^H
M^^MI^^^
/
^
-,
1.0
s
^z
10
-.
-p
>x
!
Zl _
100
y/
/
:
100 - - - "ooo * 3 ' 367fo!ooo a s 4 S67m.ooo 2
.../
3
Z_I]
...
4 s 6 T.%8o,ooo
Water Quality:
BOD 5
Suspended Solids
OXYGEN REQUIREMENT, Ib/day
OXYGEN ACTIVATED SLUDGE - UNCOVERED REACTOR
WITH CRYOGENIC OXYGEN GENERATION
Influent
(mg/l)
136
80
Effluent
(mg/l)
20
20
Design Assumptions:
Oxygen transfer efficiency = 1.53 Ib O-j/hp-hr (wire to water)
Rotating fine bubble diffusers for dissolution
Includes oxyg«n generation
Operating Parameter;
Oxygen requirement = I.I Ib 02consumed/Ib BOD5 removed
Type of Energy Required: Electrical
FIGURE 3-23
-------
PLANT CAPACITY, mgd
STAGED, PLUG FLOW OXYGEN ACTIVATED SLUDGE
100,000,000
9
7
6
a
4
3
2
10,000,000
9
a
7
6
s
>. 4
1
ef 2
li)
S 1,000,000
ELECTRICAL ENERGY
o
,°
o
o
* WO-40HB0 MM* 01 01-4 (
10,000
1
0.1
/
30
»
x
2
/
3
/
4
y -
1.0
-
:
:
__
f
-
1
rm
-----
w^
:\. -;:::..
j:
j
*
IX
- -i
- - --;-
..._
*
/
~
...
-
44- .
4
-+
i
]
1
:
J
IUU
1. - -. I
I -' 4
T
- -A
\/
.
- -
--/
i
_...
.......
--
\
-
._,
....
it
i
i- j-
. . ... _.
_
i
T.
1
j. ., ,
--
...
...
567i?ooo 2 34567i"ooo z ''"Woo ' -'--1.B6o.ooo
OXYGEN REQUIREMENT, Ib/day
OXYGEN ACTIVATED SLUDGE -COVERED REACTOR
WITH CRYOGENIC OXYGEN GENERATION
Water Quality: Influent Effluent
(mg/l)
136
80
(mg/l)
20
20
BOD 5
Suspended Solids
Design Assumptions: .
Oxygen transfer efficiency in wastewater = 2,07 rb 02/hp-hr(wire to water)
Surface aerators for dissolution
Includes oxygen generation
Operating Parameter: :
Oxygen requirement = 1.1 lj> Q^> supplied /Ib BODjj removed
Type of Energy Required: Electrical
FIGURE 3-24
-------
100,000,000
10,000,000
Q
Ul
Of
5
o
ui
o 1,000,000
Q!
Ul
u
u
Ul
100,000
10,000
lfln
100
PLANT CAPACITY, mgd
STAGED, PLUG FLOW OXYGEN ACTIVATED SLUDGE
34 S6789
100,000
3 456789
1,000,000
OXYGEN REQUIREMENT, Ib/day
Water Quality:
BOO,
Suspended Solids
OXYGEN ACTIVATED SLUDGE - COVERED REACTOR
WITH PSA OXYGEN GENERATION
Influent Effluent
(mg/l) (mg/l)
136 20
80
\20
Design Assumptions:
Oxygen transfer efficiency in wastewater = 1.53 Ib 02/hp-hr (wire to water)
Surface aerators for dissolution
Includes oxygen generation
Operating Parameter'
Oxygen Requirement-=l.l Ik 02 consumed /Ib BODg removed
Type of Energy Required: Electrical
FIGURE 3-25
-------
PLANT CAPACITY ,, migd
CONTACT STABILIZATION
LQ LO
_l,00
EXTENDED AERATION
100,000,000
9
8
7
6
5
4
3
2
10,000,000
' REQUIRED, kwh/yr
»
0
o
o
g
o
o ro w * w cn-joio
DC T
UJ 6
5
_1 4
0 3
S
13
Ul
Ul
100,000
1
6
S
4
3
£
10,000
1C
CONVENTIONAL ACTIVATED
,
/
/
S
f
-
?
-
-
>
-
-j
'
....
1
i t
i_
4
I*
i
'
...
i
t
-
y
-X
, .
. ....
/
-
2^
-
'
.1
4.7t-1
"^
--
X^
.....
SL
"T"'"
-r
\
\
t
1
I
-I
I
.UDGE
10
""" ~
-!"
.:..__-
-
(COI
....
/
t " " "
tfPLETE
.....
...
q
"t
1"
i
t- -t-
/'
-T-T
i
-
i
...
vllX)
100
- /- -
--.-p^.T-f-fW
::
-t -1
|
i
1
...
i
..-
4
-4
i
I
-fr
f
i-f
i
.
-:
t
['
\.
-
2 3 56789 2 34567 89 2 34 56789 234 56789
0 1,000 10,000 100,000 1,000,000
OXYGEN REQUIREMENT, Ib/day
ACTIVATED SLUDGE - COARSE BUBBLE DIFFUSION
Water Quality: Influent Effluent
(mg/l) (mg/l)
BOD5 136 20
Suspended Solids 80 20
Design Assumptions:
Oxygen transfer efficiency in wastewater = 1.08 Ib Og/hp-hrCwire to water, including blower)
Average value for all types of diffusers
Operating Parameters:
Conventional activated sludge oxygen requirement = 1.0 Ib 0% Consumed/Ib BODg removed
Extended aeration oxygen requirement = 1.5 Ib Ogconsumed/lb BODs removed+ 4.6 Ib
02consumed/lb NH4-N (in reactor feed) Oxidized
Contact stabilization oxygen requirement = 1.1 Ib 02consumed/lb BOD5removed-r-4.6 Ib
Og consumed/lb NH4~N (in recycle sludge)oxidized during reaerdtion FIGURE 326
-------
0.1
0
PLANT CAPACITY , mgd
CONTACT STABILIZATION
o
TOO
100,000,001
10,000,000
1,000,000
<
6
5
4
3
2
100,000
i
6
9
4
3
2
10,000
0.1
1 1
/
/
EXTENDED AERATION
o.i i.o ,
-v
CONVEN
1.0
1 1 I 1 1
/
f
/
TlOh
-V
IAL
>*-
ACTI\
... . .
y
'ATED SLUI
10
T
- -
! /
'
-j- -
r
)GE
(COMPLE
.....4-
1
j,
-
/
F
!
1 :
t
-^,
TE MIX)
100
i
y
<'
inn * i 4 5 6 7 89 2 3456789 2 345 6 7 8sT 2~
100 '.000 10,000 100,000
-.... L- . .y|.
/
'
3
/I
..... ,
1 ;
j '
-
{"
._
,. _., __
-i:ti
f-
.._
--
456 789
1,000,000
OXYGEN REQUIREMENT, Ib/doy
ACTIVATED SLUDGE - FINE BUBBLE DIFFUSION
Water Quality:
BOD5
Suspended Solids
Design Assumptions:
Influent
(mg/l)
136
80
Effluent
(mg/l)
20
20
L44 'b °2/hP hr fwire <« «f r, including blower)
Operating Parameters:
Conventional activated sludge oxygen requirement s 1.0 Ib 02 Consumed /Ib BODc removed
Extended aeration oxygen requirement = 1.5 Ib Ooconsumed/lb 800= removed 4- 4 6 Ib Oo
consumed/lb NH^-N (in reactor feed) oxidized 2
Contact stabilization oxygen requirement =1.1 Ib 02consumed/!b 600= removed +
4.6 Ib 02consumed/lb NH4-N(fn recycle sludge) oxidized during reaeration FIGURE 3-27
Type of Energy Required: Electrical
-------
0.1
PLANT CAPACITY,mgd
CONTACT STABILIZATION
1.0
EXTENDED AERATION
1,0
IQfi
CONVENTIONAL ACTIVATED SLUDGE (COMPLETE MIX)
100,000,000
9
7
6
5
4
3
10,000,000
9
T
xT 6
* 5
ERGY REQUIRED, I
*o
o
o
'o
0
DID0 N 01 *
ELECTRICAL EN
I -!
g §
-. o M u * wm-Jcwo ro w * » rn-ii
0.1
X
30
^
'
2
..
/
3
-- 1-
"T
i
T
'^ .
1.0
4
j
. . i
y
/x
...
/
-
...
7^
-
-
d
-X
...
-i
10
1 - -
i
-- - 1
/
/
T -
i
1.
/
/
-
-\^
_[__
__j..
-^
100
Y
- -4-
t
/
" *
.....
....
....
iiKS
^W
..^4 .t.i j-
.,.-
-f-
-
I
i.
i
1-
4S6ra,ooo 2 34567iBo!ooo ' "-'iW.ooo - ^--i-,o-o-o.
OXYGEN REQUIREMENT, Ib/doy
ACTIVATED SLUDGE TREATMENT - MECHANICAL AERATION
Water Quality:
BODS
Suspended Solids
Influent
(mg)l)
136
80
Effluent
(mg/l)
20
20
Surface aerator, high speed
- 1.8 Ib 02/hp-hr(w!re to water)
ovenP,rorr.eac«la,ed s.udae reauire.ent . 1.0 ,b 02«onsumed /Ib BODg "moved
Extended aeration oxygen requirement = 1.5 Ib 02 consumed/lb BOD5 removed +
4.6 Ib 02 consumed/lb NH4-N (in reactor feed) oxidized
Contact stabilization oxygen requirement=l.l Ib 02 consumed/lb BOD5 removed +
4.6 Ib Do consumed/lb NH4-N(in recycle sludge ) oxidized during reaeration
*- FIGURE 328
Type of Energy Required: Electrical
-------
PLANT CAPACITY, mgd
CONTACT STABILIZATION
1.0 1.0
JIM
EXTENDED AERATION
1.0
100,000,000 ._$.'
10,000,000
Q
111
at
13
a
IU
at
o
o:
ui
uj
_i
u
at
U
1,000,000
100,000
10,000
100
CONVENTIONAL ACTIVATED SLUDGE (COMPLETE MIX)
10 100
1,000
4 56789
100,000
456 789
1,000,000
OXYGEN REQUIREMENT, Ib/day
ACTIVATED SLUDGE - TURBINE SPARGER
Water Quality: Influent Effluent
BOD (»«/D (mg/l)
, 5 136 20
Suspended Solids 80 20
Design Assumptions:
Oxygen transfer efficiency in wastewater = 1.6 Ib 02/hp-hr (wire to water)
Operating Parameters:
Conventional activated sludge oxygen requirement s. 1.0 Ib 02 Consumed/Ib BOD5 removed
Contact stabilization oxygen requirement = I.I Ib 02 consumed/lb BODR removed + 4 6 Ib 0
eonrireT^16 sl"^e) oxidized during reaeration 5 -moved + 4.6 ,b 02
FIGURE 3-29
-------
PLANT CAPACITIES, mgd
CONTACT STABILIZATION
1,0 10
0.1
'EXTENDED AERATION"
1,0
10
100,000,000
9
8
7
6
5
0.1
CONVENTIONAL ACTIVATED SLUDGE (COMPLETE MIX)
1.0 10 100
10,000,000
g
Of
or
K 1,000,000
S \
£ «
Z !
UI
u
u
UI
100,000
I
7
6
S
4
10,000
100
m
i ti:
r
j.
EJ
^ t
-f-H-r-H
! ,, ... ,
-+ - -t
W1
T '"
r r~
-4
3 4 56789
1,000
3 456789
10,000
3 456789
100,000
OXYGEN REQUIREMENT, Ib/day
ACTIVATED SLUDGE - STATIC MIXER
il
i I.
5 6 789
1,000,000
Water Quality: Influent Effluent
(mg/l) (mg/l)
BOD5 136 20
Suxpended Solids 80 20
Design Assumptions:
Oxygen transfer efficiency = 1.44 Ib 02/hp-hr (wins to water)
Operating Parameters:
Conventional activated sludge oxygen requirement" 1.0 Ib 02 COnSUmed/lb BODs removed
Extended aeration oxygen requirement = l.5 Ib D£ consumed /Ib BODs removed -h4.6 Ib 0%
consumed/lb NH4-N(in reactor feed) oxidized .
Contact stabilization oxygen requirement = 1.1 Ib Q£ consurned/lb BOD5 removed + 4.6 Ib. 02
consumed/lb NH4-N(in recycle sludge)oxidized during reaeration FIGURE 3-30
Type of Energy Requirement: Electrical
-------
V-
PLANT .CAPACITY , mgd
CONTACT STABILIZATION
1.0 10
EMENDED AERATION
4°
100,000,000
CONVENTIONAL ACTIVATED SLUDGE (COMPLETE MIX)
1.0 10
10,000
3456 789
1,000,000
OXYGEN REQUIREMENT, Ib/doy
ACTIVATED SLUDGE -JET DIFFUSER
Water Quality:
BOD5
Suspended Solids
Influent Effluent
(mg/l) (mg/l)
136 20
80 20
Design Assumptions:
Oxygen transfer efficiency in wastewater = 1.8 Ib 02/hp-hr (wire to water)
Operating Parameters:
Conventional activated sludge oxygen requirement = 1.0 Ib 0? COnsumed/lb BODc removed
-------
PLANT CAPACITY, mgd
100,000,000
0
7
6
5
4
3
2
10,000,000
e
i S
Jf °
a *
S 3
=>
S *
en
>-
o
£ 1,000,001
5 ?
-1 6
J5
E 4
H
O
UJ
UJ 2
100,001
10,00
1.0
2
/
= =^
_ ^
3 4 5 6789
10
1
'
2
0
-
~7
-J
1°, , ...
E
J
100
y i -
.
3 4667a»oo » » *°"'"000 ' - - 10(000
AERATOR, hp
AERATED PONDS
Water Quality:
Influent
(mg/D
210
Effluent
( mg/l)
25
25
BOD5
Suspended Solids 230
Design Assumptions:
Low-speed mechanical surface aerators
Motor efficiency = 90%
Aerator etficiency= 1.8Ib Oo/hp-nr ( wire to water)
3 cells-1st cell aerated
Total detention time = 30 days
Operating Parameter:
Oxygen requirement =1.0 Ib 02/lb BOD5 removed
Typo of Energy Required: Electrical
FIGURE 3-32
-------
100,000,00
0.1
PLANT CAPACITY, mgd
1.0 10
100
10,000
iS.'ooo
AMMONIA NITROGEN OXIDIZED, Ib/day
NITRIFICATION - SUSPENDED GROWTH
3 4
5 6 789
100,000
Water Quality:
Ammonia as N
BOD5
Influent Effluent
(mg/l) (mg/l)
25 1
SO 10
Design Assumptions:
Mechanical aeration, oxygen transfer efficiency = 1.8 Ib Oj/hp-hr (wire to water)
Use of lime has no significant impact on energy requirement
Operating Parameter:
Oxygen requirement = 4.6 Ib Oj/lb NH4-N -H.Q Ib 02/lb BOD5
Type of Energy Required: Electrical
FIGURE 3-33
-------
PLANT CAPACITY , mgd
2:1
KCV.T1-L-C *:i ...
i.o 10 100
100,000,000n
a
r
6
s
4
3
10,000,000
a
t i
1 :
ce
1 *
Ul
K
g 1,000,000
2 a
i :
Ul
100,000
10,000
1
1
RECYCLE = 1:1 ...
0..! 1.0 1.0 ... _JS°
_.....-
_.-.
,_.
,
_
X
00
_.
1
_._,.
....
----
__-
J/
2
-
...
3
Ijl
TTT
1 i
~4_4
tt
1 f
. ,4-1
^/
1.0
.J. ._ - -.
Tt
ii
1 -
--
. .
"/
. , .-.,
-
RECYCLE a 0.5:1
10
| 1 M 1 1 If1 -1- ,1 : : ill
-
/
'
' I
i4
i
X
456789 2 345
1,000
^ -...-.
'
tir
Ht. . - -
f;
i i
y
/
j£ i
r~ '
t- . t
I't
1
i
..,,.
t
T ' '
I B_
r
t
/
._
t ~ '
._ 4.. 1 .1 .
/
-4-4-
- -
100
\~-
H . «.^-
, . t
- - ' --
"-ttii
_|
s' "
--'
. .. .
1 1
t **-
,
i
i
S7fo!ooo 2 3 4 56i7o8ofooo z 4 " "VoW.
MEDIA SURFACE AREA, sq. ft
NITRIFICATION, FIXED FILM REACTOR
Water Quality:
Ammonia a< N
BODS
Influent Effluent
(mg/l) (mg/l)
25 2.5
50 10
Design Assumption*:
No forced draft
Plastic media
Pumping TDH = 40 ft
Type of Energy Required: Electrical
FIGURE 3-34
-------
100,000,000g
10,000,000
o
UI
at
a
ui
ee
>
o
at
ui
ui
a
1,000,000
100,000,
10,000
PLANT CAPACITY, mgd
3456 789
1,000
DEWTRIFICATION -SUSPENDED GROWTH (OVERALL)
(Includes Methanol addition, reaeration, sedimentation and sludge recycle)
Water Quality;
Influent Effluent
(mg/l) (mg/l)
N°3-N 25 0.5
Design Assumptions;
Methanol _ Nitrogen ratio 3:1
parameters
u
Reaeration, Figure 3-37
Sedimentation and Sludge Recycle, Figure 3-38
Type of Energy Required: Electrical
FIGURE 3-35
-------
10,000,000
0.1
PLANT CAPACITY, mgd
.0 IP
100
1.000,000
EHERGY REQUIRED
«*
g
^3
RIC
UJ
LU
10,001
1,00 I
1,000
+tt
ti
tm
.11
LE
/
ft
3 4 S 6789
10,000
10,000,000
REACTOR VOLUME, cu ft
DENITRIFICATION - SUSPEKDED GROWTH REACTOR
Design Assumptions:
Temperature =15 C
Nitrate removal = 0.1 Ib NOs-N/lb MLVSS/day
Mixing device, submerged turbines, hp = 0.5 hp/1000 en ft
Methanol addition Is Included
Operating Parameter:
MLVSS=1500mg/l
Type of Energy Required: Electrical
FIGURE 3-36
-------
10,000,000
0.1
PLANT CAPACITY, mgd
1.0
1,000,000
I
Q
UJ
Hi
o
UJ
O
Of
111
u
a:
U
ui
100,000
10,001
1,000
100
1,000
4 56789
10,000
3 456789
100,000
REACTOR VOLUME, cu ft
DENITRIFICATION, AERATED STABILIZATION
REACTOR
3 456789
1,000,000
Deiing Assumptions:
Detention time = 50 min
Mechanical aeration = 1 hp/1000 cu ft
Type of Energy Required: Electrical
FIGURE 3-37
-------
PLANT CAPACITY, mgd
10,000,000g
8
7
6
5
4
3
2
J* 1,000,000
^ ' ' 9
* a
.* 7
0 6
UI 9
o:
1
o:
S
o:
Ul
z
" 100,000
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39
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PLANT CAPACITY, mgd
DENITRIFICATION - FIXED FILM, PRESSURE
Water Quality:
Nitrate as N
Influent,
(mg/l)
25
Effluent
("19/1)
0.5
Design Assumptions:
Sand media size a 24 mm
Influent pumping TDH * 15 ft
Loading rate « 1.7 gpm/sq. ft
Temp « IS^C
Depth s 6 f t.
Operating Parameters:
Backwash every 2 days for 15 min § 25 gpm/sq ft and 25 ft TDH
Methanol addition = 3:1 ( CHj OH:NO, -N)
Type of Energy Required: Electrical
FIGURE 3-39
-------
l,000,000g
a
7
6
5
4
3
2
100,000
8
7
6
REQUIRED, kwh/yr
?
g
00 N U * 0
ELECTRICAL ENERGY
-4 "°
0 M 01 * l»0>-40«° 10 U * W 01-40
,
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1,000,000
Q
iu
a
100,000
o
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10,000
1,000
'0
10
PLANT CAPACITY, mgd
5 6 789
1,000
DENITRIFICATION - FIXED FILM, UPFLOW
(BASED ON EXPERIMENTAL DATA)
Influent
(ng/l)
25
Effluent
(mg/l)
0.5
Water Quality:
Nitrate as N
Design Assumptions:
Sand media size 7 0.6 mm
Fluldiied depth =12 ft
Influent pumping TDH = 20 ft
Temperature 15 C
Operating Parameters:
Methanol addition =3:1 (CH3OH:NO3-N)
Type of Energy Required: Electrical
FIGURE 3-41
-------
100,000,000
10,000,000
o
us
tt
5
a
UI
os
at
ui
ui
cc
UI
_I
UI
1,000,000
100,000
10,000
PLANT CAPACITY, mB
-------
100,000,000
10,000,000
1
o" 2
UI
a 1,000,000
at e
S 6
<* 5
UI
J£ 4
111
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U
t
m 100,000
i
7
5
3
2
10,000
0.
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PLANT CAPACITY, mgd
SEPARATE STAGE CARBONACEOUS, NITRIFICATION AND DENITRIFICATION
WITHOUT METHANOL ADDITION
(BASED ON EXPERIMENTAL DATA)
Influent
(mg/l)
210
30
15'C
Effluent
(mg/l)
20
7.5
Water Quality:
600=
NH3-N
Temperature
Operating Parameters:
Air supply for nitrification =1.1 |b 02/lb BOD removed H-4.6 Ib 02/lb NH4-N removed
Mechanical aeration, 1.8 Ib 02 transferred/hp-hr
Denitrificatlon mixing = 0.5 hp/1000 eu ft; 3 hr detention
Final aeration stage = 1 hr detention; 1 hp/1000 cu ft
Sedimentation $ 700 gpd/sq ft; 30% recycle
Type of Energy Required: Electrical
FIGURE 3-43
-------
10,000
1,000
PLANT CAPACITY, mgd
SINGLE STAGE CARBONACEOUS, NITRIFICATION, AND DEVITRIFICATION
WITHOUT METHANOL ADDITION - ORBITAL PLANTS *
WITHOUl MtmANu
Influent
(mg/l)
210
30^
15 C
Effluent
(mg/l)
IS
4.5
-
ED QN EXpERIMENTAL DATA)
Water Quality:
BOD
NH3_N
Temperature
Operating Parameters:
Total aeration ditch detention time: 8 hr
F/M ratio =0.1 6
Rotor aeration
Sedimentation @ 700 gpd/sq ftj 50% recycle
Type of Energy Required: Electrical
* Reference, Nat.che. N.F. and Spatzler.r, G., Austrian Plant Knocks Out Nitrogen. Water & Waste, Engr.,
p. 18 (Jan. 1975) FIGURE 3-44
-------
0.1
I-
PLANT CAPACITY, mgd
HIGH LIME
TO
50
100
LOW LIME
10,000,000
1,000,000
o
ui
at
o
ui
o
Q£
IU
Z
UI
ae
u
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100,000
10,000
1,000
10
100
3 456789
10,000
456 789
100,000
FEED RATE, Ib/hr
LIME FEEDING
Design Assumptions:
Slaked lim. used for 0.1-5 mgd capacity plants
Quicklime used for 5-100 mgd capacity plants
Operating Parameters:
300 mg/|. Low Lime as Ca(OH)2
600 mg/l. High Lime as Ca(OH)2
Type of Energy Required: Electrical
FIGURE 3-45
-------
PLANT CAPACITY, mgd
1,000,000 ,
9
8
7
e
S
4
3
100,000
9
1 i
J 4
Ul
o:
3 2
or
Ul
C£
g 10,000
CK 9
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1
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10,000
FEEDING RATI:, Ib/hr
ALUM FEEDING
Operating Parameters:
Dosage 150 mg/l as At;2(SO4)3 - 14H2O
Type of Energy Required: Electrical
FIGURE 3-46
-------
1,000,000
0.1
PLANT CAPACITY, mgd
1,0 10
FEEDING RATE, Ib/hr
FERRIC CHLORIDE FEEDING
Operating Parameter:
Dosage85 mg/l as FeCI3
Type of Energy Required: Electrical
FIGURE 3-47
-------
0.1
-4-
PLANT CAPACITY, mgd
HIGH LIME
50
fr-
100
-t-
1,000,000
9
8
7
6
9
100,000
s
t£
1
UI
K
g 10,000
111
O
111
111
1,000
100
100
LOW LIME
10
50 100
/
3 4
34567?,90oo
100,000
SULFURIC ACID FEEDING RATE, Ib/hr
SULFURIC ACID FEEDING
Operating Parameter:
Dosage = 450 mg/l (high lime system)
Dosage B 225 mg/l ( low lime system)
Type of Energy Required: Electrical
FIGURE 3-48
-------
100,000,000
10,000,000
I
Jat
a
U4
1,000,000
o
OL
uj
z
UJ
t-
u
UJ
100,000
10,000
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1.1 1.0 10 100 1,000
PLANT CAPACITY, mgd
SOLIDS CONTACT CLARIFICATION - HIGH LIME, TWO STAGE RECARBONATION
(Includes reactor clarifier, high lime feeding, sludge
pumping, two stage recarbonation)
This curve is valid for chemical treatment of both raw sewage and primary effluent.
Water Quality: Influent Effluent Water Quality: Influent Effluent
( treatment of raw sewage) (mg/l) (mg/l) (treatment of 'primary effluent) (mg/l) (mg/l)
Suspended Solids 250 . 10 Suspended Solids 80 10.0
Phosphate as P 11.0 1.0 Phosphate as P 11.0 1.0
Design Assumptions and Operating Parameters are shown on the following curves: Lime Feeding, Figure 3-45
Reactor Clarifier, 3_53; Sludge Pumping, 3-4 ; Recarbonation, 3-60, 3-61 ; Recarbonalion C larifilr,
3 15
Type of Energy Required: Electrical
FIGURE 3-49
-------
10,000,000
9
8
7
6
5
4
3
2
1,000,000
g
8
7
6
5
4
3
2
100,000
7
6
P
4
2
10,000
_ -"
-^
2
0.1
^
X*
^
x
JS
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/
<
J
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/
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4
3 4 56789 2 34 56789 234 56789
1 10 '°
PLANT CAPACITY, mgdl
SOLIDS CONTACT CLARIFICATION, HIGH LIME, SULFURIC
ACID NEUTRALIZATION
(Includes reactor clarifier, high lime feed, chemical sludge pumping,
sulfuric acid feed)
This curve Is valid for chemical treatment of both primary and secondary effluents.
Water Quality: Influent Effluent Water Quality: Influent
(treatment of raw sewage) (mg/l) (mg/l) (treatment of secondary effluent) (mg/l)
Suspended solids 250 10 Suspended Solids 30
Phosphate as P 11.0 1.0 Phosphate as P 11.0
Effluent
(mg/l)
10
1.0
Design Assumptions and Operating Parameters are shown on the following curves:
Lime Feeding, Figure 3-45 ; Reactor Clarifier, 3-53 ; Sludge Pumping, 3-4 ;
Sulfuric Acid Feeding, 3-48
Type of Energy Required: Electrical
FIGURE 3-50
-------
10,000,000
ENERGY REQUIRED, kwh/y
1
o
°
? 100,000
K
o
111
10,000
9
8
7
6
5
3
2
9
8
7
6
5
4
3
2
0
ye
7
4
-------
10,000,000
g
8
7
6
5
4
3
2
x,'
1 1,000, 000
0 1
S 8
1 6
S 5
1 3
Ul
S 2
g
0 100,000
IU |
iu 7
6
5
4
10,000
^
^
z
s
X
3 4
/
^.'*
ALU
^^
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f
M .
^
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S,
//
//'
"^
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RICC
HLC
/
IRII
/
/
DE
/
56789 2 34 56789 234 SBfBS
0.1
1.0
PLANT CAPACITY, mgd
SOLIDS CONTACT CLARIFICATION, ALUM OR FERRIC
CHLORIDE ADDITION
(Includes chemical feeding, reactor clarifier, sludge pumping)
This curve Is valid for chemical treatment of both raw sewage and primary effluent)
Water Quality: Influent Effluent Water Quality:
(treatment of raw sewage) (mg/l) (mg/l) (treatment of primary effluent) (mg/l)
Suspended solids 250 30 Suspended Solids 80
Phosphate as P 11.0 1.0 Phosphate as P 11-0
Influent
Effluent
(mg/l)
10
1.0
Design Assumptions and Operating Parameters are sliiown on the following curves:
Alum or Ferric Chloride Feeding, FIgure 3-46,3-47;Reactor ClarlfIer, 3-53 ;
Sludge Pumping, 3-5, 3-6
Type of Energy Required: Electrical
FIGURE 3-52
-------
0.1
PLANT CAPACITY, mgd
LIME
1.0
100
ALUM OR FERRIC CHLORIDE
I
u
at
u
UJ
_i,
u;
10,000,000
1,000,000
8
1
9
4
_
2
100,000
(
J
6
4
3
2
10,000
7
6
s
4
3
2
1,000
10
01
^
2
x^
3
^^-x
,-:'
5 67
1
89. a
100
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3
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567
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1,000
3
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567
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2
1
4567
100
/
89
100,000
SEPARATION ZONE AREA, iq. ft
REACTOR CLARIFIER
Operating Parameters:
Separation zone overflow rate, lime c: 1400 gpd/sq ft
Separation zone overflow rate, alum or ferric chloride- m 1000 gpd/sq. ft
Type of Energy Required: Electrical
FIGURE 3-53
-------
100,000,000g
a
7
6
5
4
3
2
10,000,000
9
s
4: I
J 4
0 5
Ul
1
o
ut
o:
£ 1,000,000 9
Ul 7
3C g
5
d
5 3
o
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Ul
100,000
7
6
M
4
10,000
X
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x
xq-.,
i
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2 3456789 2 34567
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i
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i
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2
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j
i
n
...
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STACK
:.
1*
GAS C00
2
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i
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4_ . .
t
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89^ 2 3 4 =6789^ 8 3 4 » * r u^
PLANT CAPACITY, m9d
SEPARATE RAPID MIXING, FLOCCULATION, SEDIMENTATION
HIGH LIME, TWO STAGE RECARBONATION
This curve is valid for chemical treatment of both raw sewage and secondary effluent.
Water Quality: Influent Effluent Water Quality: Influent
( treatment of raw sewage) ( mg/l) ( mg/l) ( treatment of secondary effluent) ( mg/l)
Suspended Solids 250 10 Suspended Solids 30
Phosphate a, P 11.0 1.0 Phosphate as P "-0
Design Assumptions and Operating Parameters are shown on the following curves:
Lime Feeding, Figure 3-45; Rapid Mixing, 3-58 ; Flocculotion, 3-59 ; Sedimentation, 3-15 ;
Recarbonation, 3-60, 3-61- Sludge Pumping, 3-4
Type of Energy Required: Electrical
Effluent
( mg/l)
10.0
1.0
FIGURE 3-54
-------
Q
1U
E
S
oe
S
E
Ul
g
e
u
UJ
in
10,000,000_
8
7
6
5
4
3
2
1 ,000,000
9
8
7
6
5
4
3
2
100,000
7
6
5
4
3
2
10,000
. -~-"
2
^-""
3
^
4
X
S
^
6
,
78
^
/
9 Z
j/
3
^
4
/
9
/
6
''
78
/
/
t
9 2
7
/
3
4
/
5
/
6
/
7«
j
^
.
39
0.1
1.0 10
PLANT CAPACITY, mgd
SEPARATE RAPID MIXING, FLOCCULATION, SEDIMENTATION
SINGLE STAGE HIGH LIME, NEUTRALIZATION WITH SULFURIC ACID
This curve is valid (or chemical treatment of both raw sewage and secondary effluent.
Water Quality: Influent Effluent Water Quality: Influent Effluent
( treatment of raw sewage) (nig/I) (mg/l) (treatment of secondary effluent) (mg/l) (mg/l)
Suspended sol ids 250 10 Suspended Solids 30 10
Phosphate as P 11.0 1.0 Phosphate as P 11.0 1.0
Design Assumptions and Operating Parameters are shown on the following curves:
Lime Feeding, Figure 3-45 ; Rapid Mixing, 3-58; Flocculation, 3-59 ; Sedimentation,
3-15 ; Sludge Pumping, 3-4 ; Suifuric Acid Feeding, 3-43
Type of Energy Required: Electrical
FIGURE 3-55
-------
10,000,000
9
8
7
6
Q
4
3
2
f
Q- 1 ,000,000
Ul 9
2
g
E
j-
UJ 100,000
Ul |
7
6
4
t
10,000
0.1
^
2
'
X
3 4
/
/
,'
~7*~
/
/
''
?
/
/
56789 2 34567 89 2 34 Sb/Ba
1.0 10 10(
PLANT CAPACITY, mgd
SEPARATE RAPID MIXING, FLOCCULATION, SEDIMENTATION
LOW LIME, NEUTRALIZATION WITH SULFURIC ACID
Thi» curve Is valid tor chemical treatment of both raw sewage and secondary effluent.
Water Quality Influent Effluent Water Quality: Influent Effluent
(treatment of raw sewage) (mg/l) (mg/l) (treatment of secondary effluent) (mg/l) (mg/l)
Suspended solids 250 10 Suspended Solids 30 10
Phosphate as P 11.0 1.0 Phosphate as P 11.0 LO
Design Assumptions and Operating Parameters are shown on the following curves:
Rapid Mixing, Figure 3-58 ; Flocculatlon, 3-I59 ; Sedimentation, 3-15 ; Lime
Feeding, 3-45 ; Su If uric Acid Feeding, 3-48 ; Chemical Sludge Pumping, 3-4
Type of Energy Required; Electrical
FIGURE 3-56
-------
10,000,000
<
6
s
t
1
1,000,000
E
7
X 6
- 5
E 4
a 3
j
t
\ 2
j
K
: 100,000
I 9
. 0
i "
5 6
J S
5
: 3
i 2
10,000
7
0
s
4
3
2
1,000
, :
^
^*
,**
ALUM
./V
''''V
p^
r<^
*FE
_j
RRI
....
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4
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^^
;:/
RIDE
..
^
^
/^
/
i
{'
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-- H-
!
1
S 6 789
1.000
PLANT CAPACITY, mgd
SEPARATE RAPID MIXING, FLOCCULATION, SEDIMENTATION ALUM
OR FERRIC CHLORIDE ADDITION
This curve is valid for chemical treatment of both raw sewage and secondary effluent.
Water Quality: !«,, Effluent Water Quality: |nf|uent
( mg/l) ( treatment of secondary effluent) ( mg/l)
( treatment of raw sewage) ( mg/l)
Suspended Solids
Phosphate as P
250
11.0
10
1.0
Suspended Solids
Phosphate as P
Design Assumptions and Operating Parameters are shown on the following curves-
Bs R"idMi"in" 3-5
Type of Energy Required: Electrical
30
11.0
Effluent
(mg/l)
10.0
1.0
culation, 359;
FIGURE 3-57
-------
PLANT CAPACITY, mgd
100
10,000,000
9
a
6
9
4
3
Z
1,000, 000
5. e
v. 7
1 5
0 4
Ul
ENERGY REQUIR
O
O
g
o
aif M w
s
0- 4
Ul a
_1
Ul
10,000
1,000
1
2
0.1
..
_,
-
/
3 436789
10
.._.,
/
f
1
1.0
_/ _
'
1
IH
__
/
/
-
../
/
/-
.
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100 i-ooo 10'°
RAPID MIX BASIN VOLUME, cu ft
RAPID MIXING
Design Assumptions:
Detention time = 30 seconds
G = 600sec-l
Temperature = 15 C
Coagulant: lime or alum or ferric chloride
Type of Energy Required: Electrical
FIGURE 3-58
-------
10,000,000
1,000,000
o
III
D£
o
UJ
of
g 100,000
U
111
10,000
1,000
0.1
PLANT CAPACITY, mgd
0-5 1.0 5 10
3 4 5 6 789
100,000
3 456789
1,000,000
FLOCCULATION TANK VOLUME, co ff
FLOCCULATION
Design Assumptions:
Detention time = 30 minutes
G = 110 sec-1
Temperature s!5°C
Coagulant: lime or alum or ferric chloride
Type of Energy Required: Electrical
FIGURE 3-59
-------
0.1
PLANT CAPACITY, mgd
HIGH LIME
10
100
LOW LIME
0.1
1.0
10
100
100,000,000
9
7
6
3
4
3
2
10,000,000
9
8
7
6
S. 5
tS 4
* 3
a
g
1
ui
K 1,000,000
> 9
1 *
UI 5
3
H 3
a:
U 2
UI
_1
UI
100,000
1
r
6
5
4
3
2
10,000
1(
,_
_
/
^
Tl f
y
/
/
t
' X
^L_
^
...
/
/
x
4 . ./.
/
/
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1
^~
/
/
y
>_ ^ _
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/
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-
-
V
f
I
3368 34 56789 2 34 56789 2 34 56789
)0 1,000 10,000 100,000 1,000,000
CARBON DIOXIDE FEED RATE Ib/day
RECARBONATION - SOLUTION FEED OF LIQUID
CO 2SOURCE
Design Assumptions:
Vaporizer x: 25 Ib C02 Awh
Injector pumps = 42 gpm/1000 Ib CO2 @ 65 psi
Operating Parameters:
Low limes: 3000 Ib COj/mil gal
High lime * 4500 Ib CO, /mil gal
Type of Energy Required: Electrical
FIGURE 3-60
-------
PLANT CAPACITY, mgd
HIGH LIME
10
100
f-
10,000,000
<
i
I
6
5
I
$ 2
I
g"l ,000,000
i l
0 T
? »
1 4
UI
UI
* 2
u
UI
jj{ 100,000
7
6
5
4
3
2
10,000
1
I
/
/
/
LOW LIME
10
T- /-
/
/
/
/
100
-- y£
r ^/
r
Z 3456789 2 3456789 2
100 1,000 10,000
3
4
5 6 789
100,000
CARBON DIOXIDE FEED RATE, scfm
RECARBONATION - STACK GAS AS CC^ SOURCE
Design Assumptions:
Stack Gas .10% Cfy , 0.116 Ib C^ /cu ft at standard conditions (60°F, 14.7 psia)
operating temperature, 1100F (following scrubbing)
Loss to atmosphere = 20% »«.ruuDingj
Injection pressure =8 psi
Low lime = 3000 Ib CO /mil gal
Operating Parameters:
Low lime = 3000 I
High lime = 6000 Ib COg / mil gal
Type of Energy Required: Electrical
FIGURE 3-61
-------
PLANT CAPACITY, mgd
0.1
35/4. SCREEN
1.0
10
o
in
O.
100
I
100,000,000
9
7
e
s
4
3
2
10,000,000
8
6
s
4
5
2
|
> 1,000,000
* 9
i S
\ :
\ s
11
J 2
11
100,000
7
6
s
4
i
S
10,000
1
2
.0
0.1
. .
/
/
5456789 2
10
X
S 4
23 /
' -
,'
X
4 SCREEN
1.0
---.3t
-t*
-I
X
-
X
i
/
56789 2 34567
100
10
,/i
/
/ '
^
>/^
/
f
100
/
89 2 3 4 S 6 789
1,000 10,000
SUBMERGED SCREEN AREA, sq ft
MICROSCREENS
Woter Quality: Influent Effluent
(mg/l) (mg/l)
Suspended Solid* (35^) 20 10
Suspended Solids (23)d 20 5
Design Assumptions:
Loading rate (35>i)=10.0 gpm/s«j ft
Loading rate (23ft)*. 6.7 gpm/sq ft
Operating Parameters:
80% submergence
Type of Energy Required: Electrical
FIGURE 3-62
-------
PLANT CAPACITY, mgd
D
111
OL
5
o
iii
DC.
O
Of
UJ
z
10,000g
i
"3
6
S
4
3
1,000
(
1
6
4
3
2
100
8
6
S
4
3
2
'S
7
6
5
4
3
2
1
,-41-
/
/ /
V
_/1
/
/
p
/
/
/
/ '
1.0
PRE
/
//
//
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SSUR
/
/
/
E F
1r
_X
/^
IL
/
i.
TERS
/
/
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/
w*~
/
//
//
/
X GRAV
/
/
^
ITY
/
FIL
/
/
£ /
^r
.TERS
100
/
/,
.//
f f
/
/
/
f
r
/
-/
YTT
2 34 56789 2 34 56789 234 56789 2 34 56789
10 100 1,000 10,000 100,000
SURFACE AREA, sq ft
PRESSURE AND GRAVITY FILTRATION
Water Quality: Influent
(mg/l)
Suspended Solids 20
Design Assumptions:
Effluent
(mg/l)
Includes filter supply pumping (or allowance for loss of treatment system head);
filter backwash supply pumping, and hydraulic surface wash pumping (rotating arms).
Pump Efficiency: 70%; motor efficiency: 93%
Filter and back wash head: gravity filters, 14ft TDH;
pressure filters, 20 ft TDH.
Surface wash pumping: 200 ft TDH
Filtration rate (both filters): 5 gmp/sq ft
Back wash rate (both filters): 18 gpm/sq ft
Hydraulic surface wash rate(rotating arm)1.-1 gpm/sq ft (average)
Operating Parameters:
Filter run: 12 hrs. for gravity, 24 hrs. for pressure.
Back wash pumping (both filters): 15 min. per backwash.
Surface wash pumping (both filters): 5 min. per backwash.
Type of Energy Required: Electrical
FIG01FWE3-63
-------
PLANT CAPACITY, mgd
GRANULAR CARBON ADSORPTION - DOWNFLOW PRESSURIZED
CONTACTOR
Wator Quality: Influent Effluent
(mg/l) (mg/l)
Suspended Solids 20 10
COD x 40 15
Design Assumptions:
8 X 30 mesh carbon, 28 ft carbon depth, 30 min. contact.
Filtration head: 28 ft TDK (carbon depth) + 9 ft. TDH, (piping and freeboard)
Filtration pumping: 7 gpm/sq ft @ 37 ft TDH, (average)
Back wash pumping: 18 gpm/sq ft: 37 ft TDH, (averageO (average)
Operating Parameters:
Operate to 20 ft head loss building before backwashing.
Backwash pumping: 1 5 min per backwash
Typs of Energy Required: Electrical
FIGURE 3-64
-------
10,000,000
1,000,000
o
UJ
O
OC
111
5
Q!
U
HI
100,000
10,00
1,000
3 456 789
1,000
PLANT CAPACITY, mgd
GRANULAR CARBON ADSORPTION - DOWNFLOW GRAVITY CONTACTOR
Water Quality: Influent Effluent
(mg/l) (mg/l)
Suspended Solids 20 10
COD 40 15
Design Assumptions:
8 X 30 mesh carbon
3.5 gpm/sq ft
30 min contact ( 14 ft carbon depth)
Operate to 6 ft headless buildup before baekwashing
Type of Energy Required: Electrical
FIGURE 3-65
-------
10,000,000
1,000,000
Q
Ul
I
UI
et
>
(9
Ul
_J
3
5
_i
Ul
100,000
1,00
10,000 _ S_-
000
PLANT CAPACITY, mgd
GRANULAR CARBON ADSORPTION - UPFLOW EXPANDED BED
Water Quality:
Suspended Solids 20
COD
Design Assumptions:
Influent Effluent
(mg/l) (mg/l)
20
15
30 minutes contact
12 X 40 mesh carbon
15% expansion, 7 gpm/sq ft (28 ft carbon depth)
3 ft freeboard
Type of Energy Required: Electrical
FIGURE 3-66
-------
PLANT CAPACITY, mgd
CLARIFIED SECONDARY EFFLUENT
TO 100
B 1
100,000,000
CLARIFIED RAW WASTEWATER
10
10,000,000
a
UJ
a:
UJ
z
UJ
_l
<
y
o2
u
ui
1,000,000
100,000
10,0000
000
000
5
03
E
a
o
UJ
UI
D
',000
100
2 3 4 56789 "00°
1,000,000
GRANULAR ACTIVATED CARBON REGENERATED, Ib/day
GRANULAR ACTIVATED CARBON REGENERATION
Design Assumptions:
Electricity includes furnace driver, afterburner, scrubber blowers and carbon conveyors.
Fuel required per Ib Carbon regenerated:
Furnace a 3,600 Btu
Steam z 1,600 Btu
Afterburners 2,400 Btu
Operating Parameters:
Carbon dose: Clarified raw wastewater, 1500 Ib /mil gal
Clarified secondary effluent, 400 Ib /mil gal
Type of Energy Required: Electrical and Fuel
FIGURE 3-67
-------
0.1
PLANT CAPACITY, mgd
1.0. 10
10,000,000
100,000
CLINOPTILOLITE BED (4 ft depth), sq ft
ION EXCHANGE FOR AMMONIA REMOVAL, GRAVITY AND PRESSURE
Water Quality:
Suipended Solids
NH3-N
Design Assumptions:
Influent
(mg/l)
5
15
Effluent
(mg/l)
5
0.1-2
ISO bed volumes throughput/cycle
6 bed volumes/hr loading rate
Gravity bed, available heads 7.25 ft
Pressure bed, average operating head = 10 ft
Includes backwash but not regeneration nor regenerant renewal
10% downtime for regeneration
Type of Energy Required: Electrical
FIGURE 3-68
-------
PLANT CAPACITY, mgd
1 ,000,000
u 100,000
1 ?
-* 6
0 5
UJ
Oi 4
5 3
o
UJ
U. 2
o
C£
z 10,000
UJ g
j 8
< 7
U 6
£ s
U 4
UJ
-i 3
UJ
1,000
I
5
100
0.1
. I
,
y
/
-
/
--
/
... JT-j._
:lf
; --
1
/- :
1.0
ill J r
.- . _.
-f - - -
j...
\
t
--
/
/
1
1
1
:~rTi
1 f
I' fl
'T '
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j
!
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10
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,
3T
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X
r
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3
f > > !
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f
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t
i
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i. »-
1 i
T
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f
--
6 789
100,000
CLINOPTILOLITE BED (4ft depth), sq ft
ION EXCHANGE FOR AMMONIA REMOVAL - REGENERATION
Design Assumptions:
Regeneration with 2% NaCI
40 BV/regeneration; 1 regeneration/24 hrs
Total head = 10 ft
Does not include regenerant renewal
Applicable to gravity or pressure beds
Type of Energy Required: Electrical
FIGURE 3-69
-------
10,000,000
WITHNHoRECOVERY
._ WITHOUT NH3 RECOVERY
3 4 56 89 2 3456789 2 3456789
1,000
PLANT CAPACITY, mgd
ION EXCHANGE FOR AMMONIA REMOVAL - REGENERANT RENEWAL.
BY AIR STRIPPING
Design Assumptions:
Regeneront softened with NaOH, clarified at 800 gpd/sq ft
40 BV/regenoration cycle; 150 BY throughput per cycle
Regenerant air stripped; tower loaded at 760 gpd/sq ft with 565 cu ft air/gal
Stripping tower overall height s 32 ft
Ammonia recovered in absorption tower with
Type of Energy Required: Electrical
FIGURE 3-70
-------
1,000,000
0.1
PLANT CAPACITY, mgd
1.0
^
-._ .
^
- f
. J
1
44144
-+-H-H-
IT;!
[' ! !- -
--j -l-t-r-*
r~
T
100
1,000,000
100,000
10
100
89
1,000
' 89
10,000
CLINOPTILOLITE BED (4ft. depth), sq. ft.
ION EXCHANGE FOR AMMONIA REMOVAL, REGENERANT RENEWAL
BY STREAM STRIPPING
Design Assumptions:
Steam stripping used
Spent regenerant softened with soda ash at pH 12
Steam stripper height y.18 ft
4.5 BV/regeneration cycle; 150 BV throughput/ion exchange cycle
Power mcludes softening, pH adjustment, pumping to stripping tower
Fuel based on 15 Ib steam required,/],000 gal wastewater treated
NH^ recovered
Type of Energy Required: Electrical and fuel
FIGURE 3-71
-------
100,000,000
9
8
7
6
5
4
3
2
.10,000,000
S 9
ELECTRICAL ENERGY REQUIRE
i i
§ N w * woNoxo0 N w * w m-jco
D.1
^
2
X
3
^
4
/
^
TOTAI
/.
'S
f S
/
}
/
/
^
'
'/
Ft
/
//
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I.NS
7
S*r
i'.^H.
S
/
JG
/
/
/
56789 2 34 S6789 S> 4 4 &b/by
1,0 10 1(
PLANT CAPACITY, mgd
AMMONIA STRIPPING
Water Quality: Influent
pH 11
Air temp.,*F 70
NH3-N, mg/l 15
Design Assumptions:
Pump TDH B 50 ft.
Operating Parameters:
Hydraulic loading sl.O gpm/sq ft
Air/Water ratios 400 cu ft/gal
Type of Energy Required: Electrical
Effluent
11
70
3
FIGURE 3-72
-------
100,000,000 °iL
10,000,000
D
Ul
O£
o
IU
Of
>-
u
an
u
UJ
_i
u
u
Ul
1,000,000
9
100,000
10,000
PLANT CAPACITY, mgd
10
DECHLORINATION WITH ACTIVATED CARBON
DECHLORINATION WITH SULFUR DIOXIDE
100
3 4 S 67 89
1,000
3 456789
10,000
3 4 S 6 7 89
100,000
3 456789
1,000,000
CHLORINE USAGE, Ib/doy
BREAKPOINT CHLORINATION WITH DECHLORINATION
Water Quality:
NH4_N
Influent
(mg/l)
IS
Effluent
(mg/l)
0.1
Design Assumptions:
Dosage ratio, CI2 :NH 4-N is 8:1
Residual CI2=3 mg/l
Detention time in rapid mix = 1 min.
Sulfur Dioxide feed ratio, S02 :Clj = 1:1
Activated carbon pumping, TDH = 10 ft
Type of Energy Required: Electrical
FIGURE 3-73
-------
PLANT CAPACITY, mgd
O
Ul
ee
o
Ul
Of
s
o:
ui
ui
d
u
3,000,000
3
6
S
4
3
2
1,000,000
9
8
6
s
3
2
100,000
0
d
6
s
t
10,000
(
5
t
1,000
1
2
3
0.1
CHLORIN
/:
'?
AT 1C
x
N 1
7
MTH D
J
456789 2 34561
10
1.0
ECHLORIN/
--' yX-
, Ys CH
TIO(
x
LOR
^
IN/
_
kTION 1
P
1
-T2^
-.
WITHOUT Dl
-^
'/
CHL
V
OR
^
INATK
00
/
)N
l
'8?oo 2 3 4 5S78i?ooo 2 3 " 0bf1S,
CHLORINE FEEDING RATE, Ib/day
CHLORINATION AND DECHLORINATION FOR DISINFECTION
Effluent
20
20
200
Water Quality: Influent
BODs, mg/l 20
Suspended Solids, mg/l 20
Coliform, no./lOO ml > 1,000
Design Assumptions:
Evaporator used for dosages greater than 2000 Ib/day
Dechlorination by S02 assuming an S02:CI2 ratio of 1:1 and S02 : CI2 residual of 1 : 1
No evaporator for SO2
Operating Parameters:
Chlorine dosage r 10 mg/l
Chlorine residual = 1 mg/l
Type of Energy Required: Electrical
FIGURE 3-74
-------
£3
UJ
O
UJ
UJ
z
UJ
U
CK
u
UJ
10,000,00
1,000,000
100,000
c
e
6
3
2
10,000
7
6
5
4
3
a
1,000
r*rr
-
- :
--
1
--*
PLAN
V°
jX'*
T CAPACITY
tll]X 1
/ mcf
d
10
xx
1 ' °°'"° ' * ' 5678i°° 2 3 4 56'
FfH-h
zz"
(/
Tooo 2
^-
3
100
_
-^~-
---
456 789
100,000
FEED RATE, Ib./day
CHLORINE DIOXIDE GENERATION AND FEEDING
Design Assumptions:
Chlorine Dioxide dosage is 4 mg/l (equivalent to 10 mg/l Cl2)
Sodium Chlorite: Chlorine Dioxide ratio a. 1.68 to 1
Chlorine: Chlorine Dioxide ratio = 1.68 to 1
Type of Energy Required: Electrical
FIGURE 3-75
-------
PLANT CAPACITY, mgd
10,000,000
8
7
6
B
4
3
2
1,000,000
9
a
7
6
u
£ 2
s
JJ
a;
>- 100,000
B 9
* a
z I
LU ,
< 4
J
L>
Ul 2
U
10.00C
i
i
1,00
/
/
/
'
2
c
_^_
7
3 4 5 6
.1
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/
789
1
AIR FEEC
~7
X
0
y
~\ /
'-.-£
'/A
y-
i~S
/
ox
10
A
" r
VGEN F
7
/
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7^
,
i
~2
00
0.1
10
,000
OZONE GENERATED, ton/yr
OZONE DISINFECTION
WATER QUALITY: Influent
Suspended Solids, mg/l 10
Fecol collforms/100 ml 10,000
Effluent
10
200
Design Assumptions:
Ozone generated from air @ 1.0% wt. concentration and oxygen (8 2.0
Operating Parameters:
Ozone dose * 5 mg/l
Type of Energy Required: Electrical
FIGURE 3-76
-------
PLANT CAPACITY, mgd
n
UJ
at
5
o
111
o:
(9
a:
u
oe
u
UJ
1 0,000, 0(
1,000,00<
100,000
1
6
s
I
10,000
8
7
6
5
4
3
2
1,000
)
/
^
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/
^
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.,. .... , .
/
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F
y
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10
L
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r
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iqp
^
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1
-f
1
1
-fr
IT
iL
1 00,000
ION EXCHANGE MEDIA (4 ft depth), sq ft
ION EXCHANGE FOR DEMINERALIZATION, GRAVITY AND
PRESSURE
Influent Effluent
(mg/l) (mg/l)
500 SO
Water Quality:
TDS
Design Assumptions:
Loading rate - 3 gpm/ej ft
Gravity bed, available head = 7.25 ft
Pressure bed, average operating head = 10 ft
Includes backwash but not regeneration nor re gene rant disposal
Type of Energy Required: Electrical
FIGURE 3-77
-------
100,000,000
8
7
6
5
4
3
2
.c
j| 10,000,000
- 9
Q 8
UJ 7
i J
a »
UI
CC 4
I 3
UJ
UJ 2
3
E
5 1,000,000
UI |
UJ 7
100,000
/
X
2
x
3 4
/
/
/
XI
/
/'
x
/
A
7"
56789 2 34 56789 2 3 «* ooroa
0.1
1.0
10
100
Water Quality:
PH
Turbidity, JTU
TDS, mg/l
PLANT CAPACITY, mgd
REVERSE OSMOSIS
Influent Effluent
6 7
<1.0 0.1
500-1300 100-200
Design Assumptions:
Feed pressure s 600 psi
Single pass system
Operating Parameters:
Water recovery: 0.1-1 mgd 75%
1-10 mgd 80%
10-100 mgd 85%
Type of Energy Required: Electrical
FIGURE 3-78
-------
PLANT CAPACITY, mgd
J
a
in
at
o
UJ
at
19
ce
ui
UJ
u
S
u
UJ
100,000,00
10,000,00
1
1
1,000,000
1
6
5
4
3
2
100,000
I
e
5
4
3
z
10,000
__x
/ ,
0.
-V
,
^
/
^_
::Z
i
1.0
CENTER PIVOT -w/
-f
/
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:X
r~
/
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^
^-x*
7 "
7
SOLID
-''X
SET
if a
-------
PLANT CAPACITY, mgd
O
Ul
a
ui
10,000,000
a
6
5
4
3
1,000,000
9
3
| 6
* s
1 4
J
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5
y ,
U 2
It
>-
S
5 100,000
r f
ui ~
< I
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11 2
10,001
1
1
1,000
/
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-ir
/
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^^
^
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/
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t.. - .
1.0
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10,000,00
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BY FLOODING
Design Assumptions:
Infiltration/percolation, TDHs.5 ft
Overland flow, TDK a 10 ft
Disposal time is 5 month/yr
Type of Energy Required: Electrical
FIGURE 3-81
-------
PLANT CAPACITY, mgd
100,000,000
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INFILTRATION/PERCOLATION AND OVERLAND FLOW
BY SOLID SET SPRINKLERS
Design Assumptions:
Infiltration/percolation spray, TDHs.115 Ft
Overland flow spray, TDH = 175 ft
Disposal time is 5 month/yr
Type of Energy Required: Electrical
FIGURE 3-82
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PLANT CAPACITY, mgd
WASTEWATER TREATMENT PLANT
BUILDING HEATING REQUIREMENTS
Design Assumptions:
Four fresh air changes/hr
Storm windows and insulated walls and ceilings
70 percent fuel utilization factor
(See Chapter S, pages 5-2 to 5-7)
FIGURE 3-83
-------
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PLANT CAPACITY, mgd
Note: See chapter 5, pages 5-8 to 5-10
WASTEWATER TREATMENT PLANT
BUILDING COOLING REQUIREMENTS
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GRAVITY THICKENING
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Type of Energy Required : Electrical
FIGURE 3-85
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AIR FLOTATION THICKENING
See Table 3-5 for design assumptions and operating parameters.
Curve corresponds to a maximum air requirement of 0.2 Ib/lb solids
and average of 0.3 scfm air/sq ft surface area
Type of Energy Required = Electrical
FIGURE 3-86
-------
TABLE 3-6
BASKET CENTRIFUGE, SLUDGE CHARACTERISTICS
Sludge
Primary + WAS
Primary + WAS (+FeC13)
WAS
Digested Primary
Digested Primary + WAS
Digested Primary + WAS
(+FeCl3)
Feed Concentration,
2.0
1.5
1.0
8.0
4.0
4.0
Cake Concentration,
9-12
9-10
8-9
25
20
20
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00 1,000 10,000 100,000 1,000,000
DEWATERED SOLIDS CAPACITY, cu ft/day
BASKET CENTRIFUGE
Design Assumptions:
Operating hp Is .375 tlmas rated hp
See Table 3-6 for specific sludge characteristics.
Multiple units required above 800 eu ft/day opacity
Operating Parameters:
Machines run for 20 min, are off for 10 mln
10 mln allowed for unloading, restarting and attaining running speed
Type of Energy Required: Electrical
FIGURE 3-87
-------
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SLUDGE QUANTITY, ton/day (dt, solids)
ELUTRIATION
Sludge
1. Digested primary @ 8% solids
2. Digested primarytW.A.S. § 4% solids
3. Digested prirnarytW.A.S. (tFcCI-j) fd 4% solids
Design Assumptions:
Overflow rates = 800 gpd/sq (t for 1
500 gpd/sq ft for 2 & 3
Mixing energy C £ 200 sec"! for 5 min per stage
TDH - 30 ft for sludge and 25 ft for water
Operating Parameters:
Two stage, countercurrent system with, separate mixing & settling tanks
Wash water to sludge ratio = 4:1
Type of Energy Required: Electrical
FIGURE 3-88
-------
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THERMAL TREATMENT CAPACITY, gpit
HEAT TREATMENT
Design Assumptions:
Reactor conditions - 300 psig at 350 F
Heat oxchangerAT* 50°F
Continuous operation
See Table 5-9 for sludge description and text in Chapter 5
Curve includes:
Pressurization pumps
Sludge grinders
Post-thickener drives
Boiler feed pumps
Air compressors
Type of Energy Required: Electrical
FIGURE 3-89
-------
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HEAT TREATMENT - WITHOUT AIR ADDITION
Design Assumptions:
Reactor conditions- 300 psig at 350°F
Heat exchanger AT = 50°F
Continuous operation
See Table 5-9 for sludge description and text of Chapter 5.
Curve Includes!
Fuel to produce steam necessary to raise reactor contents to operating temperature
Type of Energy Required: Fuel
FIGURE 3-90
-------
THERMAL TREATMENT CAPACITY, gpm
HEAT TREATMENT - WITH AIR ADDITION
(Curve! of2)
Design A»»umptloni:
Reactor conditions- 300 psig at 350 F
Heat exchanger AT = 50°F
Continuous operation
See Table 59 for sludge description and text of Chapter 5.
Curve Includes:
Fuel to produce steam necessary to raise reactor contents tin operating temperature
Type of Energy Required: Fuel
FIGURE 3-91
-------
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HEAT TREATMENT - WITH AIR ADDITION
(Curve 2 of 2)
Design Assumptions:
Reactor conditions 300 piig of 350 F
Heat exchanger AT = 50°F
Continuous operation
See Table 5-9 for sludge description and text of Chapter 5.
Curve includes:
Fuel to produce steam necessary to raise reactor contents to operating temperature
Type of Energy Required: Fuel
FIGURE 3-92
-------
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SLUDGE QUANTITY, ton/day (dry solids)
CHEMICAL ADDITION
(Digested Sludges)
Design Assumptions:
See Table 3-8 preceding Figure 3-96 for chemical quantities
Pumping head =10 ft TDH
Curves Include:
Chemical feeding and handling
Sludge pumping
Sludge-chemical mixing
Type of Energy Required: Electrical
FIGURE 3-93
-------
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SLUDGE QUANTITY, ton/day (dry solids)
CHEMICAL ADDITION
(Undigested Sludges)
Design Assumptions:
Pumping head =10 ft TDH
Curves include:
Chemical feeding and handling
Sludge pumping
Sludgechemical mixing
Type of Energy Required: Electrical
FIGURE 3-94
-------
Sludge Type
Primary
Primary +
Primary +
Low Lime
Primary +
High Lime
Primary + WAS
Primary +
(WAS + FeCl3)
(Primary + FeClJ
+ WAS
TABLE 3-7
VACUUM FILTRATION
Design Assumptions
Thickened to 10% solids
polymer conditioned
Percent
Solids
To VF
10
85 mg/1
dose
Lime conditioning
Thickening to 2.5% solids
300 mg/1 lime dose
Polymer conditioned
Thickened to 15% solids
600 mg/1 lime dose
Polymer conditioned
Thickened to 15% solids
Thickened to 8% solids
Polymer conditioned
Thickened to 8% solids
Fed 3 & lime conditioned
Thickened primary sludge
to 2.5%
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to 5%
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2.5
15
15
3.5
Typical
Loading
Rates,
(psf/hr)
8-10
1.0-2.0
10
Percent
Solids
VF Cake
25-38
15-20
32-35
28-32
4-5
3
1.5
16-25
20
15-20
Waste Activated
Sludge (WAS)
WAS + Fed.
Digested Primary
Digested Primary
+ WAS
Digested Primary
+ (WAS + FeCl3)
Tertiary Alum
Thickened to 5% solids 5 2.5-3.5
Polymer conditioned
Thickened to 5% solids 5 1.5-2.0
Lime + FeCl~ conditioned
Thickened to 8-10% solids 8-10 7-8
Polymer conditioned
Thickened to 6-8% solids 6-8 3.5-6
Polymer conditioned
Thickened to 6-8% solids 6-8 2.5-3
FeCU + lime conditoned
Diatomaceous earth 0.6-0.8 0.4
precoat
15
15
25-38
14-22
16-18
15-20
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VACUUM FILTRATION
See Table 3-7 for design assumptions.
Operating Parameters:
2 scfm/sq ft
20-22 inches Hg vacuum
Filtrate pump, 50 ft TDH
Curve includes: drum drive, discharge roller,
vat agitator, vacuum pump, filtrate pump. '
Type of Energy Required: Electrical
FIGURE 3-95
-------
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r
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cu
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lickening
r
-------
10,000,000
f 1,000,000
5
s
o
HI
cc
(9
OC
UJ
1U
o
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100,000
10,000
9
j
j
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6
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t
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6
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7
6
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NT SOLIDS =
X
X
x"
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x
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x^^
^
6%
^ - 8%
2 34 56789 2 34 56789 2
10 100 1>00o
3
4
-
56 789
10,000
FILTER PRESS VOLUME, cu ft
FILTER PRESSING
See table (preceding) page for design assumptions.
Operating Parameters:
includes*'0" baSed O" C°ntinu°US °Pefation. 225 ps) operating pressure
,UmPjhydraUliCa"y driVe"' P08'""6 disP'acement piston pump)
Opening and closing mechanism p'
Type of Energy Required: Electrical
FIGURE 3-96
-------
o
Ul
cc
o
UI
cc
cc
UJ
IU
<
o
10,000,000
9
8
7
6
5
4
3
2
1,000,000
9
8
7
6
5
4
3
2
j 100,000
I £
7
6
i
10,000
2
3
4
Cl
_ ^
/
/
LIME SLU
.ASSIFIO
/
7
/
/
DGE
\TION-
//
/
_^1_
X /
V/ /
/
^ * DEWA"
.^
./
ERIN
G
56789 2 34567 89 2 a t o e , o^
FLOW, gpm
CENTRIFUGING
Operating Conditions:
Power consumption based on continuous operation
Dewatering accomplished with low speed centrifuge, G= 700 sec-1
Sludge Type
Primary t Low Lime
Tertiary »- Low Lime
Primary -t 2 Stage High Lime
Tertiary + 2 Stage High Lime
Conditions
No classification
No classification
Classification followed by dewatering
Classification followed by dewatering
Type of Energy Required: Electrical
FIGURE 3-97
-------
1,000,000
I
O
D
UJ
at
5
o
UJ
o:
o
Q£
UJ
Z
UJ
u
£
G
UJ
|
1,000
1 000
10
5 6 789
10,000
SLUDGE QUANTITY, gpm
SAND DRYING BEDS
Design Assumptions:
Power consumption based on pumping to drying beds at TDH = 15 ft
Fuel consumption based on:
drying to 50% solids, 70 Ibs/cu ft
loading with front end loader, 8 gal/hr use of diesel fuel (140,000 Bfu/gal)
15 minutes required to load 30 cu yd truck
See Table 33 for quantities of various sludges/mi I gal treated
Type of Energy Required: Electrical and fuel
FIGURE 3-98
-------
10,000,000
9
8
6
5
4
3
s. z
E
"^1,000,000
t 1
6
0 5
1U
te. 4
3
0 3
U4
6 *
Oi
Ul
g 100,000
^ I
i 2
1 :
Sl 3
Z
10,000
7
6
4
3
1,000
/
2
/
~ r ~
lif
.y
/
/
i**
^ .
/*
WERAGECI
J_x£
f^
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^«-
l^^^
jb
»"
IN
'ER[
^j**
RAIN ELE\
.-
'ATI
1 LE'
- 20
ON
'El
"ft./ m
! '
3 ' 5 6 8 2 3 4 S6789 2 34 S 6 7 89 z a » oo'"
10 100 1,000 10,
ANNUAL SLUDGE VOLUME, mil gal
SLUDGE PUMPING
Design Assumptions:
4% solids maximum ( Dilute to 4% if greater)
4 inch pipeline minimum, design velocity 3fps
Pipeline effective *c* factor 85
Pumping based on centrifugal non clog or slurry pumps, 68% efficiency
20 hours per day average operation
Operating Parameters:
See Table 3-9 for sludge characteristics for disposal.
Type of Energy Required: Electrical
FIGURE 3-99
-------
TABLE 3-9
SLUDGE CHARACTERISTICS
SLUDGE DISPOSAL
Liquid Sludge
Dewatered Sludge
Percent
Sludge Type Solids
Primary
Primary + Fed.,
Primary + Low Lime
Primary + High Lime
Primary + WAS
Primary + (WAS+FeCl3)
(Primary + FeCl3) + WAS
Waste Activated
Sludge (WAS)
WAS + FeCl3
Digested Primary
Digested Primary
+ WAS
Digested Primary
+ (WAS + FeCl3)
Tertiary Alum
Tertiary High Lime
Tertiary Low Lime
5
2
5
7.5
2
1.5
1.8
1.0
1.0
8.0
4.0
4.0
1.0
4.5
3.0
Vol ume
(gal /mil gal)
2,760
16,500
11,940
15,680
12,565
21,480
20,960
11,330
18,400
1,210
3,680
5,455
8,390
21 ,690
13,235
Volume For
Pumping I1)
(Pipeline) Percent Volume^)
(gal/mil gal) Solids (cu vd/mil aal)
-fl\ (2\
3,450V ; 31l '
16,500 18^
14,925(1) 34(2)
29,400(1) 30(2)
12,565 20(2)
21,480 20^
20,960 18^
11,330 15^~
18,400 15^
f l\ ( y\
2,420{ ' 3V >
3,680 18^
5,455 17^2^
8,390 17^2^
24,400(1) 50(3)
13,235 50^3)
2.7
11.3
10.8
24.2
7.8
9.9
12.9
4.7
7.6
1.9
5.0
7.9
3.0
12.1
4.9
(!) Sludge diluted to 4.0% for pumping
(2) Vacuum filtration
(3) Centrifuge
(4) Average sludge density 50 Ib/cu.ft
-------
/- TRUCK CAPACITY cu yd
10,000
I
7
e
s
4
3
2
1,000
9
a
Illlon Btu/one way mlle/yi
o
»«J° K « » Ofl»-
FUEL REQUIRED, m
MM* aa~ia«P it w * a o»H
/
^=*
<?-
Y
/
7
i
/
/
/
s
2
/
/ '
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z ~
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r
3 4 8 6769
10
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/
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/
j
'- ^
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15 ^
30
^
:: 1
,
T~4~5678 "'23 4 86789 234 867B3
100 1,000 10,000
ANNUAL SLUDGE VOLUME, 1,000 cu yd
DEWATERED SLUDGE HAUL BY TRUCK
Design Assumptions'
1 gal dl«iol(#2) a 140,000 Btu
Dl«i«l powsrod dump trucks
Operating Parameters:
Operation 8 hr per day
Average speed; 25 mph for first 20 miles and 35 rnph thereafter
Truck fuel use 4.5 mpg avg
See Table 3-9 for sludge characteristics for disposal.
Type of Energy Required: #2 Diesel fuel
FIGURE 3-100
-------
100,000
10,000
1,000
!
6
3
t
3
2
100
I
s
4
3
2
10
/
^
Y
/
£
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>
/
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i/^
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^
/
/
r BA RG
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300,00
EC/
n
/ 500,000
< 850,000
g; P ; 1,000,000-
: : =
J_ .
« = * aerus z 34 56789 2 s 4 5 6 7s' " 2~
1 I" 100 1,000
00
3
OPACITY,
gal
456 769
10,000
ANNUAL SLUDGE VOLUME, 1,000 cu yd
LIQUID SLUDGE HAULING BY BARGE
Design Assumptions:
1 gal marina diesel = 140,000 Btu
Non-propelled barges moved with tugs
Operating Parameters:
Operation 24 hrs per day
Average speed 4 mph
Tug size: 300,000 gal barge - 1,200 hp
500,000 & 850,000 gal barge - 2,000 hp
1,000,000 & 2,000,000 gal barge - 2,500 hp
See Table 3-9 for sludge characteristics for disposal.
Type of Energy Required: Marine diesel fuel
FIGURE 3-101
-------
100,000
TRUCK CAPACITY, gal
r
0
5
4
3
2
<
= 10,000
E 9
IRED, million B to/one way
*
o
g
B> ra u * a osa
g T
U I
OS 6
J 8
S
" 3
2
100
1
e
s
4
3
2
10
1
yr
V^
r
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/
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f
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^
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t
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r
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/
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;^=
^ 2,500
, 5,500
2 34 86789 2 34 56789 2 34 56789 2 34 56789
10 100 1,000 10,000
ANNUAL SLUDGE VOLUME, mil gal
LIQUID SLUDGE HAULING BY TRUCK
D»lgn Assumption*:
1 gal dlo.ol (#2) = 140,000 Btu
Diesel powered tank trucks
Operating Parameters:
Operating 8 hrs per day
Average speed; 25 mph for first 20 miles and 35 mph thereafter
Truck fuel use 4.5 mpg avg
See Table 3-9 for sludge characteristics for disposal.
Type of Energy Required: #2 Diesel fuel
FIGURE 3-102
-------
s
m
=J
d
UJ
K
UJ
=>
U.
1,000,000
5
100,000
j
(
I
s
3
*
10,000
8
7
6
5
4
j
2
1,000
7
6
5
4
3
2
100
./
/
/
/
/
/
/
/
_ !
/
/
/
/
^ LA
ND SPREAD
2 34 06789 2 34 56789 2 34 56789 2
1 10 100 1,000
ING
3
4
56789
10,000
ANNUAL SLUDGE VOLUME, mil gal
UTILIZATION OF LIQUID SLUDGE
Design Assumptions:
Fuel use: spreading truck - 2 gal/trip
1 gal diesel (#2) = 140,000
Operating Parameters:
1600 gal big wheel type spreader, IS minute round trip. Truck is self loading.
See Table 3-9 for sludge characteristics for disposal.
Type of Energy Required: #2 Diesel fuel
FIGURE 3-103
-------
100,000
10,000
CQ
§
o
UJ
a:
a
ui
o:
1,000
10,000
ANNUAL SLUDGE VOLUME, 1,000 eu yi
UTILIZATION OF DEWATERED SLUDGE
Design Assumptions:
Fuel use: Bulldozer - 8 gal/hr
Front end loader 8 gal/hr
Spreading truck - 3 gal/trip
1 gal dlesel (#2) = 140,000 Btu
,es bulldozer «.. per 30 cu yd trucMoad .1 s.udge
Spreading: 7.2 cu yd big wheel type spreader, 20 m.nute tr.p time
See Table 3-9 for sludge characteristics for disposal.
Type of Energy Required: #2 Diesel fuel
FIGURE 3-104
-------
10,000,OOC
!
6
a
A
3
2
1,000,000
£
6
o-
u
a: 2
O
Ul
* 100,000
S 9
£ $
UJ *
ECTRICAL Eh
M w * a <
UJ
10,000
i
9
4
3
2-
1,000 .
_*!
£
.X*
-
1 1 li J
jf
~7
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/**' /
/ ,
~^~ ~Fi
X,
|pd
/
S FL
X
_y
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y y'''
X y
it/1000 cu ft
//
;f??
/ fX/
^ Jy/X^
J
M
100 ' " " ° "f "?«« Z 3 4 S6789 2 34 867 9" 2"
100 MOO 10,000 1 00,000
,^-
s
\
/
/
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IRH
XINC
MEC
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3
^20
/y7
^^10
^'
^
X
VlOOO c
HANICAI
M
?--
j t
456 739
1,000,000
DIGESTER VOLUME, eu ft
ANAEROBIC DIGESTER - HIGH RATE
Design Assumptions:
Continuous operation
20 ft submergence for release of gas
Motor efficiency varies from 85% to 93% depending on motor size.
Type of Energy Required: Electrical
See Chapter 5, pages 5-11 to 5-14 and Figure 3-106 for fuel requirements.
FIGURE 3-105
-------
1,000,000
a
7
6
9
4
3
2
100,000
9
a
7
6
4
>*
v. 3
0- 10,000
UJ g
o: 8
« i
uj S
_1 4
3 3
U.
1,004
100
1 i r i I M II "~" JL ' '
1 | 1 1 1 1 1 1 1 C
Curv* Mn. Sludae Tvoe
^^V
inn
1
2
3
4
5
6
7
8
'//
^fj
Z
Primary
Primary -r-FeCIs
Primary 4- Low Lime
Primary + High Lime
Primary+W A S
Prlmary+(W AS + F
(Primary 4-FeCls) + V
WAS
_
'/,
^ /^
456'
/
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r8f.ooo
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//<
y
z
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y
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- -
/,
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^
y
_
2, 5& 7
i
!71?,ooo 2 ' 4 B67Wo.ooo " ° " -Wtfb.o
SOLIDS, Ib /day
THERMOPHILIC ANAEROBIC DIGESTION
are «hown for northern s,atei. for centra, locations mu.tip.y by 0.5. for southern
locations multiply by 0.3.
Operating Parameter: ^
Digester temperature 130 F
See Figure 3-105 for mixing energy
See Table 3-3 for sludge characteristics.
Type of Energy Required: Fuel or Natural Gas
FIGURE 3-106
-------
1
o"
tu
Q!
O
1U
u:
o
Q£
111
111
U
UJ
100,000,00
10,000,000
1
1,000,000
8
6
4
2
z
100,000
1
6
s
4
3
z
10,000
J
....
/^
Jill Ai" '\
4 '/
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ff
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8 DAYS
-
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t .'
,116 DAYS Zj
- - -.
AERA
d 4 4 5bf8» Z 34567 89 Z 34567 89 Z
10 100 1,000 10,000
'^S-
/s
'//
/
4 DA
*
^
H&-
^
DETENTI
YS
TION DEVICE
DIFFUSED A
MECHANICAL
3
j
f f /
' ^
r
'^
'/
ON -
R
456 789
100,000
BOD|N _ Ib /day
AEROBIC DIGESTION
Design Assumption*:
Energy based on oxygen supply requirements; mixing assumed to be satisfied.
Mechanical aeration based on 1.5lb02 transfer/hphr
Diffused aeration based on 0.9lb Oj transfer/hp-hr
Temperature of waste c20C
Oxygen for nitrification is not included in values presented for nitrification Op demand 4 BOD
demand multiply value from curve by 1.3
Type of Energy Required: Electrical
FIGURE 3-107
-------
100,000,000
6
8
4
3
2
10,000,000
9
e
ERGY REQUIRED, kwh/yr
^3
O
O
*0
IOHBO to w * wo>-
2 6
!
*f «
5 3
t
UJ 2
tu
100.00C
10,00
2
3
458
r J^
10
~x
/
0 1!
i BOEX
t
/ '
7L .
inn
/1 000 cu
_
//
/'
t/da
4
r
,200
\fr
/
Ib BOD
/
S
c/1000 cu ft
^
/day
^
/
X
f
1 ooo 10,000 100,000
10
BOD!N - Ib /day
THERMOPHILIC AEROBIC DIGESTION
D««lgn Assumptions!
Process is autothermophllle . .
Pur« oxygen provided for oxygen transfer having (he tollowlng power demands:
l.Shp/1,000 eu ft. mixing
2.9 Ib Oj /hp-hr PSA generation
4.2 Ib Oj /hp-hr Cryogenic generation
Cryogenic systems assumed for greater demands nhan 5 ton/day
Type of Energy Required! Electrical
FIGURE 3-108
-------
100,000,000
10,000,000
I
r REQUIRED, kwh/yr
"o
g
"o
g
BIO ro w * o> m-4
5 I
K 6
UJ
Ul 4
< s
y
Ul
_i
w 100,000
7
e
s
4
3
2
10,000
_
/
/^
'
/
/
:: =
/
2 34 96789 2 34 56789 2 3
1 10 100
4
/
/
5 6 789 2
1,000
/
3
456 789
10,000
SLUDGE FLOW, gpm
CHLORINE STABILIZATION OF SLUDGE!
Design Assumptions:
Operating pressure = 35 psi
Recirculation ratio a 5:1
Chlorine feed = 4 lbs/1,000 gal
Type of Energy Required: Electrical
FIGURE 3-109
-------
10,000,000
9
a
6
0
4
3
2
1,000,000
e
6
S
4
£ *
1 2
*
O
Ul
5 100,000
0 1
ui |
CH 7
5
o:
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z
ELECTRICAL E
o
"o
o
iao° N w
1,000
1
00
2
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:: =
1
1
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7«
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t
^
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ko
rA^
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^/
pf^
X x
X
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/
345678i!ooo Z '^'IMOO ' J 4-LJ 100,000 - 1,000,000
SLUDGE QUANTITY, Ib dry solids/day
LIME STABILIZATION OF SLUDGEES .
Design Assumptions:
Pumped feed of slaked lime
Mix lime and sludge for 60 seconds at G = 600 sec-1
Sludge pumping not included ( see Figure 3-4 if pumping required)
Type of Energy Required: Electrical
FIGURE 3-110
-------
LU
O 31
T fe
CO eC
LLJ
uu =
oa uj
F a!
*
cu
CU )-»»->
cn \
i- OO C S-
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at cu E
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CM O CM O i O
1 1 1 1 1 1
O O O O LO O
r**^ MD oo vo tj3 to
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z: CM en z: CM CM
CM
o Is* LO en ^ co
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a
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CO i CO i CM i
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100,000
7
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10,000
9
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100
r 1 1 | I I I I
Curve No.
1
2
3
_ X
5
7
8
9
4
/
V
/
-r- .
/
f
4
r
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-?
/,
/
S udo8 Tvoe
Primary
Prim.* FeCI3
Prim. 4- Low Lime
Pr!m.+W.A.S.
Prim.'»-(W.A.S.-f-F«Cl3
(Prim.* FeCI3)-fW.A.!
W.A.S.
W.A.S.4- FeCIs
DigMtad Primary
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1,500
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MULTIPLE HEARTH FURNACE INCINERATION START-UP FUEL
Design Assumptions:
Use In conjunction with Figure 3-111 to determine total fuel required.
Heatup time:
Effective Hearth Area
sq ft
less than 400
400-800
800-1400
1400-2000
greater than 2000
Heatup time
hr
18
27
36
54
108
Operating Assumptions:
Heatup time to reach 1400* F temperature
Frequency of start-up Is a function of Individual system
Type of Energy Required: Fuel OH or Natural Gas
FIGURE 3-112
-------
o
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cc
i
cc
111
111
en
s
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100,000,000
8 I
7
6
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MULTIPLE HEARTH FURNACE INCINERATION
Design Assumptions:
Solids Concentration, %
14-17
18-22
23-30
31
Operating Parameter:
System operates 100% of the time.
Loading Rates, ,b/hr/sc, ft (wet sludge)
6.0
6.5
7.0
8.0
10.0
11.0
12.0
12.0
FIGURE 3-113
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1,000,000
<5
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at
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100
Curve No.
TT-
1
2
3
4
5
6
7
8
9
^
/
/
/
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Sludge Type
Primary
Prim.* FeCl3
Prim. 4- Low Lim*
Prim.*-W.A.S,
Prim.f(W.A.S.+
(Prim.* FeCI3)+.
W.A.S.
W.A.S.+ FeCIs
Digested Primary
4
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DRY SLUDGE FEED, Ib/hr
FLUIDIZED BED FURNACE INCINERATION
Design Assumptions:
Heat value of volatile solids is 10,000 Btu/lb
.Loading rates, Ib/sq ft/hn
Curve No. Rote
1,9 14
2,4,6.7,8 6.8
3 18
5 8.4
See Table 3-10 preceding Figure 3-111 for more design assumptions
Operating Conditions:
Combustion temperature is 1400° F
Downtime Is a function of individual system
40% excess air, no preheater
Startup not included, 73,000 Btu/sq ft for startup
Type of Energy Required: Fuel oil or Natural Gas
FIGURE 3-114
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BED AREA, iq ft
FLUIDIZED BED FURNACE INCINERATION
See Table 3-10 preceding Figure 3-1
Operating Parameter!!
Full time operation
Typ«of Energy Required: Electrical
for design assumptions
FIGURE 3-115
-------
10,000
1,000,000
100,000
10,000,000
E
a"
a
ui
Ul
3
10,000
10
ANNUAL DRY SOLIDS PRODUCT - ton/yr
SLUDGE DRYING
Design Assumptions:
Continous operation
Dryer Efficiency 72%
Product moisture content 10%
Power includes blowers, fans, conveyors
Type of Energy Required: Fuel and Electricity
Fl GURE 3-116
-------
100,000
Q
UJ
tc
i
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EC
H
O
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10,000
q
8
7
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TREATMENT CAPACITY, gpm
WET AIR OXIDATION
Design Assumptions:
Reactor pressure
Primary + WAS a 1700 pslg
WAS « 1800 pslg
Continuous operation
See Table 5-9 for sludge description and text In Chapter 5
Curve Includes:
Pressurlzatlon pumps
Sludge grinders
Decant tank drives
Type of Energy Required: Electrical
Note: Fuel Is required only at start-up
Boiler feed pumps
Air Compressors
FIGURE 3-117
-------
lo.ooo.ooOg
10,000,000
1,000,000
o
111
at
o
ui
ae
a
ce
ui
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100,000
10,000
1,000
3 4 5 6 7 69
10,000
HEARTH AREA, sq ft
J.IME RECALCINING - MULTIPLE HEARTH FURNACE
3 4'8-6789 '°°°
100,000
Design Assumptions:
Continuous operation
Multiple hearth furnace
7 Ibs/sq ft/fir loading rate (wet basis)
Gas outlet temperature = 900*F
Product outlet temperature -1400°F
Power includes center shaft drive, shaft cooling fan, burner turboblowers, product cooler, and induceddraft fan
Sludge Composition: CaC03 Mg(OH)2 Other Inerts Combustibles
Primary, 2 stage high lime 65% 2% 13% 20%
Tertiary, low lime 71 10 16 3
Tertiary, 2 stage high lime 86.1 4.3 6.] 3.5
Type of Energy Required: Fuel and Electrical
FIGURE 3-118
-------
-------
CHAPTER 4
SECONDARY ENERGY REQUIREMENTS
This chapter presents some of the secondary energy required in municipal
wastewater treatment. Secondary energy is defined in this report as the
energy required to manufacture the consumables used in municipal wastewater
treatment. Secondary energy estimates are provided for the following con-
sumable materials used in wastewater treatment processes discussed in
Chapter 3.
activated carbon
alum
ammonium hydroxide
carbon dioxide
chlorine
ferric chloride
lime (calcium oxide)
methanol
oxygen
polymer
sodium chloride
sodium hydroxide
sulfur dioxide
sulfuric acid
Data from these curves and tables is essentially supplemental to any cost-
effectiveness comparison a municipality may perform in submitting a planning
or design proposal. Indirectly, however, the data might indicate which
consumables will be relatively more expensive in the future, as high energy
costs imply higher dollar costs. Municipal planners might wish to take
note of this fact in choosing treatment trains, as lower energy costs often
imply lower user charges. Because of the limitations of the data, however,
it would be incorrect at this time for municipal planners to build into
present value alternatives cost comparisons relatively higher or lower costs
of a particular consumable over time.
Energy required to manufacture consumable materials was estimated based on
data obtained from several sources including: (1) manufacturing companies,
(2) technical journals and books, and (3) calculations based on descrip-
tions of production processes contained in the technical literature or
furnished by manufacturers.
4-1
-------
Specific energy requirements for some materials are somewhat difficult to
obtain for the following reasons:
1. Some companies consider this type of information proprietary and will
not release details of the manufacturing process or the energy required.
Other companies could not, or would not, furnish energy data for a
variety of reasons such as, a) believed it would jeopardize com-
petitive position, and b) insufficient records.
2. Some manufacturing processes produce more than one product, e.g.,
chlorine and sodium hydroxide, or a primary product and by-product,
e.g., ammonia and carbon dioxide.
3. By-product or waste from one process used as feedstock in manufacturing
process, e.g., ferric chloride and sulfuric acid.
4. Most chemicals are produced by more than one process, or with different
methods of obtaining feedstock, with different energy requirements,
e.g., sulfuric acid, carbon dioxide and methanol.
The estimated energy requirements for production are summarized in Table 4-1.
Data from Table 4-1 is shown graphically in Figures 4-1 through 4-14 with
treatment plant capacities and typical dosages. These figures show the
principal production energy for each of the 14 consumables used in munici-
pal wastewater treatment. The additional abscissas relate energy require-
ments to facility si zings and application dosages. When using these
additional abscissas, the user should add the term "per day" to the regular
ordinates and abscissas shown on the graphs.
If two products are manufactured in one reaction, the total amount of energy
utilized is attributed to the product under discussion. The total amount of
4-2
-------
energy required does not include any special environmental clean-up require-
ments. The manufacture of most of the consumables shown in Table 4-1 does
not require special air or water pollution control equipment. The pro-
duction of lime and activated carbon does require the use of air pollution
control equipment, but the energy required for this equipment is not shown
in Table 4-1.
Energy required for the transportation of consumables is not included in
Table 4-1 or in the figures. The following discussion illustrates a method
that may be used to estimate transportation energy requirements.
Consumable materials are normally transported by railroad and/or truck. A
25 ton diesel truck, averaging 4 mpg and using fuel with a heat value of
142,500 Btu/gal, requires 1,425 Btu/ton-mile. An energy study for the Ford
Foundation1 gives 670 Btu/ton-mile for railroad transportation of freight.
A one-way delivery distance of 100 miles by truck then requires about
142,500 Btu/ton (or about 285,000 Btu/ton assuming the truck returns empty).
This amount of energy for delivery varies from about 14 percent of the total
required for alum production to 0.3 percent for activated carbon.
Activated carbon, lime and some of the other consumables are usually de-
livered to or near the point of Use by railroad. Activated carbon probably
requires the longest delivery distance of any consumable for most plant
locations. A railroad transportation distance of 1500 miles plus 50 miles
round trip by truck gives a total energy requirement for transportation of
about 1,148,000 Btu/ton. This amount of energy for transportation is about
1.1 percent of the total energy required for production of activated carbon.
"Energy Consumption in Manufacturing," report to the Energy Policy Project
of the Ford Foundation, Ballinger Publishing Company, Cambridge, Mass., 1974.
4-3
-------
TABLE 4-1
ESTIMATED ENERGY REQUIREMENTS FOR THE PRODUCTION
OF CONSUMABLE MATERIALS
Material
Activated Carbon
Alum
Ammonium Hydroxide
Carbon Dixoide
Chlorine
Ferric Chloride
Lime (Calcium Oxide)
Methanol
Oxygen
Polymer
Salt (Sodium Chloride)
Evaporated
Rock & Solar
Sodium Hydroxide
Sulfur Dioxide
Sulfuric Acid
Fuel
Million Btu/ton
102*
2*
41*
2
42
10
5.5*
36 *
5.3
3*
4*
0.5
37
0.5
1.5*
Electricity
kwh/lb
4.9
0.1
2.0
0.1*
2.0*
0.5* '
0.3
1.7
0.25*
0.1
0.2
0.024*
1.8*
0.024*
<0.1
Indicates principal type of en.ergy used in production.
4-4
-------
1,000
c
7
6
9
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2
100
3 9
5 8
c 7
° 6
IODUCTION ENERGY, mill
_A
to° ro w ^ u\
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6
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1
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400 Ib /mil gal
Tertiary granular
Carbon treatment
2,500 Ib /mil gal
I PC Powdered
Carbon treatment
I ACTIVATED CARBON, Ib
I .... ,,
1.0
0.1
I 1
10
1
1.0
,
100 mgd
I
I .
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10 mgd
ACTIVATED CARBON
SECONDARY ENERGY REQUIREMENTS
FIGURE 4-1
4-5
-------
S
to
E
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000
8
7
6
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9
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4
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2
10
7
6
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1
/mil
y gra
i trea
Ib/m
10
gal
nular 1
ment
II gal
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10,000
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. | 1
01 1.0 ""
0 mgd
Carbon treatment
ACTIVATED CARBON
SECONDARY ENERGY REQUIREMENTS
FIGURE 4-1
4-6
-------
3
5
C9
K
ai
ui
§
O
Q
O
cc
a.
10,000
£
7
6
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3
t
1,000
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4
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2
100
1
7
6
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.
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1,000,000
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AMMONIUM HYDROXIDE, Ib
10
100 mgd
AMMONIUM HYDROXIDE
SECONDARY ENERGY REQUIREMENTS
FIGURE 4-3
4-7
-------
1,000
9
8
7
6
5
4
3
2
S 100
c 9
PRODUCTION ENERGY, millio
.A
* oiosaxo0 ro w * w cn-Joo
1
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/
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i 10
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D^4 DIOXIDE, Ib
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100 n
/
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/.
-
1,000,
agd
-I
300 mg/l
10
100 mgd
CARBON DIOXIDE
SECONDARY ENERGY REQUIREMENTS
FIGURE 4-4
4-8
-------
s
tr
LU
HI
o
u
a
§
a
100,000
c
8
7
6
5
4
7
2
10,000
9
8
7
6
5
4
3
2
1,000
7
6
5
4
3
2
100
/
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ff
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2 3 4 5 6'7 6
100 1
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9 2 345678
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0,000
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5
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100,000
10 mg/l
CHLORINE, Ib
1 1 1 1
1 10
100 mgd
I ' 1
135 mg/l 1 10
j
10'
0 mgd
CHLORINE
SECONDARY ENERGY REQUIREMENTS
FIGURE 4-5
4-9
-------
100,000
9
8
7
6
5
4
3
2
1 0,000
9
_ ft
PRODUCTION ENERGY, kvrt
_L
* ~9.
0 °
j ° M 01 * OlO-JOXO0 N W * « m-"
00
50 mg/l
l__
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FERRIC Ct
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^
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4LORIDE, Ib
1
^ 10 1 °° m9d
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100,000
FERRIC CHLORIDE
SECONDARY ENERGY REQUIREMENTS
FIGURE 4-6
4-10
-------
m
§
5
tc.
HI
Ul
o
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3
a
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a
1,000
9
8
7
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100
9
8
7
6
5
4
3
10
7
6
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3
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1
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.
300 mg/l
400 mg/l
i
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, ,
1 . " " " ' »
10 100 mgd
i i
1 'I
10 100 mgd
LIME (CALCIUM OXIDE)
SECONDARY ENERGY REQUIREMENTS
FIGURE 4-7
4-11
-------
i,ooo9
8
7
6
5
4
3
2
s 10°
m 9
PRODUCTION ENERGY, million
_J>
-L -i to oi A wtn^iaxo0 ro w -fr tn cn^iaa
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METHANOL, Ib
60 mg/l 1
10
100 mgd
METHANOL
SECONDARY ENERGY REQUIREMENTS
FIGURE 4-8
4-12
-------
>
-------
1,000,000
9
8
7
6
5
4
3
2
100,000
9
8
6
5
4
3
2
10,000
7
6
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1,000
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POLYMER, Ib
! 1
10
100 mgd
POLYMER
SECONDARY ENERGY REQUIREMENTS
FIGURE 4-10
4-14
-------
10,000
1,000,000
1200 Ib /mil gal 1
100 mgd
SODIUM CHLORIDE
SECONDARY ENERGY REQUIREMENTS
FIGURE 4-11
4-15
-------
1,000,000
9
8
7
6
5
4
3
2
100,000
9
6
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4
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1,000
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SODIUM HYDROXIDE, Ib
I
375 Ib /mil gal
4760 Ib /mil gal
1
10
Y-
100 tngd
I
10 1°(
SODIUM HYDROXIDE
SECONDARY ENERGY REQUIREMENTS
FIGURE 4-12
4-16
-------
i
a
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111
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Q.
101
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6
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i i
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SULFUR DIOXIDE
SECONDARY ENERGY REQUIREMENTS
FIGURE 4-13
4-17
-------
1 ,000,000
9
8
7
6
5
4
3
2
100,000
9
8
7
6
5
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10,000
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10
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IIC ACID, Ib
1
100 IT
/
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1,000
gd
450 mg/l
10
100 mgd
SULFURIC ACID
SECONDARY ENERGY REQUIREMENTS
FIGURE 4-14.
4-18
-------
CHAPTER 5
IN-PLANT ENERGY RECOVERY AND RECYCLING
INTRODUCTION
The purpose of this chapter is to (1) present heat requirements for various
wastewater treatment processes and (2) describe and evaluate processes
and methods that could be used to supply some of the heat and electrical
energy required by wastewater treatment plants. Heat requirements are
presented for the following:
Building heating and air conditioning
Anaerobic digestion
Heat conditioning of sludge to improve dewatering
Wet oxidation of sludge
Lime recovery by recalcination
Granular and powdered carbon regeneration
Ion exchange regenerant renewal
After the section on heat requirements, the remainder of this chapter
is devoted to the following recovery and recycling systems:
Anaerobic Digester Gas - Gas production, methods for use, including elec-
trical power generation, and cost estimates are presented.
Incineration - Various incineration systems are briefly described and
waste heat recovery is discussed. Incineration of sludge and combinations
of sludge and solid waste are evaluated. Cost estimates are given for
multiple hearth furnaces. Energy requirements for air pollution control
devices are not included in the curves.
5-1
-------
Pyrolysls - Several commercially available pyrolysis systems are briefly
described and the potential for energy recovery and reuse is discussed.
Treatment of sludge and solid waste combined is evaluated.
Heat Treatment - Energy requirements and the potential for waste heat
recovery are discussed.
Heat Pumps - Systems to utilize the heat in wastewater and air are de-
scribed and cost estimates presented.
Solar Energy - Solar energy systems are briefly described and an example
for space heating is presented.
Energy Conservation - Conservation procedures that could be used in
existing wastewater treatment facilities are discussed.
HEAT REQUIREMENTS IN IdASTEHATER TREATMENT PLANTS
Building Heat
Energy required for space heating in a wastewater treatment plant depends
upon several factors including: (1) building size, (2) location (climate),
and (3) type of construction. The degree-day (deg-day) system is one
method of estimating energy required for space heating.
The deg-day is defined as 65°F minus the mean temperature for the day. If
the mean temperature of the day is 65°F or greater, then the number of deg-
days for heating is zero. The deg-day method is based on the findings of
the American-Gas Association that the quantity of energy required for
heating is proportional to the number of deg-day. For example, a building
requires twice as much heat on a day when the temperature is 45°F (20 deg-
day) than when it is 55°F (10 deg-day). Table 5-1 shows the average number
of deg-day per month computed from about 30 years of record, for 25 cities
in the United States.
5-2
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-------
The general equation used for estimating energy required for space heating
E = 24 XH x D (5-1)
E = energy consumption, Btu
U = utilization efficiency
H = hourly heat loss for building, Btu/hr/°F
D = deg-day, °F day
The utilization efficiency is the ratio of the heat loss from the struc-
ture to the heat input and is a function of several factors including con-
trol of heating equipment and type of construction. Values from 45 to 90
percent have been reported. The hourly heat loss can be computed using
ASHRAE methods1 or can be measured directly. It is expressed in Btu/hr/°F
and includes the heat losses through the walls, ceiling, floor, windows and
infiltration air. This quantity is highly variable from structure to struc-
ture depending on insulation, building materials and ratio of floor area to
volume, Some representative heat loss values have been published for in-
sulated and uninsulated walls and ceilings.2 Based on these values, and
neglecting air infiltration rate, H values were determined for the follow-
ing three cases:
Case A corresponds to an uninsulated building of 1,000 sq ft
with H = 820 Btu/hr/°F.
Case B is a 1,000 sq ft building with 3.5 in. wall insulation,
6 in. ceiling insulation and storm windows. The insulation
and storm windows give a reduction of about 45 percent in the
heat loss rate and H = 450 Btu/hr/°F.
Case C is the same as Case B, but includes double glazed win-
dows and floor insulation and gives H = 325 Btu/hr/°F.
5-4
-------
These three cases are shown in Figure 5-1 as a function of the number
of deg-day and a U of 0.70. Infiltration air can substantially increase
the values in Figure 5-1. For example, an infiltration rate of 1.5
times the building volume per hour will increase the values for Cases
A, B and C by 13, 24 and 33 percent, respectively.
In wastewater treatment plants, 4 to 6 air changes per hour is a common
design standard. This rate will increase the heating requirement and
should not be neglected. For example, assuming 4 air changes/hr, 70
percent utilization factor, 5000 deg-day climate, and 1000 sq ft area
with an 8 ft ceiling gives an additional heat requirement of about 99
million Btu/yr.
Building heating requirements for wastewater treatment plants can be
estimated from the above information if the total floor area is known.
Typical floor areas as a function of treatment plant size are given in
another EPA report4 and are shown in Figure 5-2. The data in these
tables and figures can be used to estimate building heating require-
ments. As an example, the curves shown in Chapter 3, Figure 3-83 were
derived from these data for Los Angeles, New York and Minneapolis.
This simple method of estimating heating loads does not apply to large
commercial buildings. The relationship of the external heat losses
and the internal heat gains must be considered when determining the
total system energy balance. For example, some larger buildings gene-
rate enough heat from operating equipment that cooling is required through-
out most of the year. Other buildings may require simultaneous cooling
of the hotter inner rooms and heating of the cooler outer rooms.
5-5
-------
250
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CASE A:
UNINSULATED
B:
ADDED WALL a
CEILING INSULATION
WITH STORM WINDOWS^
CASE C:
_WALL a CEILING
INSULATION
DOUBLE GLAZED WINDOWS
a FLOOR INSULATION
34567
THOUSAND, deg doy/yr
10
ESTIMATED HEAT REQUIREMENTS
1000 SQ FT BUILDING
5-6
FIGURE 5-1
-------
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PLANT CAPACITY, mgd
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ESTIMATED FLOOR AREA FOR WASTEWATER
TREATMENT PLANTS
(FROM REFERENCE 4)
5-7
FIGURE 5-2
-------
Building Cooling
Similar to the deg-day method for estimating heating requirements a
method of estimating energy consumption for cooling has also been de-
vised.5 This method uses cooling deg-day above 70°F as a criterion.
Although tabulated values of cooling deg-day are not available, approxi-
mate values can be obtained from published deg-day maps. Estimated
values at the same 25 cities used for heat estimates are shown in Table
5-2.
The cooling deg-day method is based on the following equations:
E = PT (5-2)
T = (24 HD) / C (tm-70) (5-3)
yearly energy requirement, kwh/yr
power input to equipment, kw
predicted operating time of equipment, hr
average hourly cooling load on a design day,
Btu/hr
number of deg-days above 70°F, deg-day
total cooling capacity of equipment, Btu/hr
where
E
P
T
H
D
C
tm
design outdoor dry-bulb temperature minus
one-half the daily temperature range, °F
The cooling capacity, C, of the air conditioning unit may be determined
experimentally, or obtained from the manufacturer. The cooling load or
average hourly heat gain, H, is dependent on factors such as the sun's
radiation, daily temperature range, shading effect, insulation, the
number of people and internal heat sources in the building.
5-8
-------
TABLE 5-2
ESTIMATED COOLING DEGREE DAYS FOR 25 CITIES
CITY
Atlanta, Ga
Baltimore, Md
Birmingham, Ala
Boston, Mass
Charlotte, NC
Chicago, 111
Cincinnati, Ohio
Cleveland, Ohio
Dallas, Texas
Denver, Colo
Detroit, Mich
Houston, Texas
Kansas City, Mo
Los Angeles, Cal
Mi ami, Fla
Milwaukee, Wis
Minneapolis, Minn
New Orleans, La
NY,NY
Philadelphia, Pa
Pittsburgh, Pa
St. Louis, Mo
San Francisco, Cal
Seattle, Wash
Trenton, NJ
DESIGN
DRY BULB
TEMPERATURE
92
92
94
88
94
91
92
89
99
90
88
94
97
90
90
87
89
91
90
90
88
94
77
79
90
TEMP RANGE
(°F)
19
17
21
16
20
15
21
22
20
28
20
18
20
20
15
21
24
16
1
21
19
18
14
19
19
DEG-DAYS
COOLING
1200
530
1250
0
750
175
400
100
1260
100
85
1625
580
45
2500
80
100
1675
150
100
250
550
0
0
250
5-9
-------
Based on the following assumptions the cooling loads in Btu/hr/100 sq
ft, for Los Angeles, New York, Minneapolis and Miami were determined
by the Carrier 2,4 hour method7 to be 7,970; 8,817; 7,408 and 8,640;
respectively.
Roof overhang
Building size
Window area
Construction
Exterior
24 in.
1000 sq ft
15 percent of floor area
frame or heavy masonry,
pitched roof
light color
The heat .gain from people must be added to the above values. One esti-
mate of treatment plant staff8 is: 3.8 people for a 1 mgd plant, 28
for 10 mgd and 153 for 100 mgd plants. The system cooling load is 360
Btu/hr/person.7
Equations (5-2) and. (5-3) can be used to determine the total energy
required for cooling if the unit capacity and power input are known.
In this report it is assumed that the cooling capacity 'is equal to the
cooling load and that the system coefficient of performance for cooling
is 2.5.5
Using the cooling load, H, and the data in Table 5-2 and Figure 5-2
building cooling requirements can be estimated for various treatment
plant sizes. As an example, the curves shown in Chapter 3, Figure 3-
84, were derived from this data for Los Angeles, New York, Minneapolis
and Miami. Effects from an average amount of infiltration air are in-
cluded; however, air changes of 4 to 6 volumes per hour could increase
the energy requirements in Figure 3-84 b"y 50 to 100 percent.
5-10
-------
Anaerobic Digestion
Heat is required in the anaerobic digestion process to (1) raise the
temperature of the influent sludge to the level of the digester, and (2)
compensate for heat losses from the digester through its walls, bottom
and cover.
The WPCF Manual of Practice No. 8 contains the following discussion on di-
gestion temperatures.
10
The optimum temperature of sludge digestion in the mesophilic range
is about 98°F; in the thermophilic range, about 128QF. Although
the optimum sludge-digestion temperature may vary somewhat with
local conditions, the temperature generally adopted for sludge
digestion falls within the range of 90° F to 95° F.
The heat required to raise the influent sludge temperature can be calculated
from the following relationship:
Q
W
C
= WC (TD - V
= heat required, Btu
= weight of influent sludge, Ib
(5-4)
specific heat of sludge, 1.0 Btu/lb/°F
for 1-10% solids sludge
temperature in digester, °F
temperature of influent sludge, °F
The WPCF Manual of Practice No. 8, gives the following criteria for digester
heating:10
Data accumulated from numerous digester installations have made it
convenient to use factors for estimation of heat losses from digesters
without considering separately the loss through each element of the
5-11
-------
digester. For the normal installation it is assumed that a
1°F drop in temperature occurs for the entire tank contents
in 24 hr. A correction factor is applied for outside tem-
perature, depending upon location and special conditions,
such as the presence of ground water. For each 1,000 cu ft
of contents, this amounts then to 1,000 x 62.5 x 1.0 = 62,500
Btu per day; or 62,500 = 2,600 Btu per hr. Correction factors
24
for geographical location by which the value of 2,600 Btu per
hr is multiplied are as follows:
Northern United States 1.0
Middle United States 0.5
Southern United States 0.3
The following organic loading rates are used in standard and high rate
digestion:
Loading. Ib VS/day/cu ft
Standard rate 0.03 to 0.1
High rate 0.1 to 0.4
Detention time of 30 days are often used for standard rate digestion
and 15 to 20 days for high rate digestion.
Digester heat requirements in this report are based on loadings of 0.05
and 0.15 Ib VS/day/cu ft. These criteria give the following digester
capacities:
Digester Capacity
(cu ft/mil gal)
Solids Total Volatile Total** Loading
Sludge Content Solids Solids Sludge (Ib VS/day/cu ft)
Type (percent) (Ib/mil gal) (Ib/mil gal) (Ib/mil gal) 0.05 0.15
Primary
Primary
5
4.5*
1,155
2,096
690
1,446
23,100
46,600
13,800 4,600
28,900 9,600
*Thickened
**Water and Solids
5-12
-------
The total heat required for digestion at 95°F is shown in Figure 5-3
for primary sludge and Figure 5-4 for primary plus waste activated
sludge. These heat requirements are based on the above criteria for
sludge heating and digester heat loss and 75 percent heat transfer ef-
ficiency.
Heat Treatment of Sludge
Requirements for heat conditioning of sludge to improve dewatering and
wet oxidation of sludge are discussed in the following heat treatment
section of this chapter. Fuel requirements for heat treatment of various
sludges are summarized in Table 5-9 and are shown in Figures 3-89 through
3-92.
Lime Recalcination :
' ' ' n "-'"1" -l ,.
Recalcining may be accomplished in multiple hearth or fluidized bed
furnaces. The energy required is dependent on several factors such as
sludge composition, furnace loading operating temperatures and type
of furnace. Heat requirements for multiple hearth furnaces are shown
in Figures 3-111 and 3-112 and for fluidized bed furnaces in Figure 3-114.
Granular and Powdered Activated Carbon Regeneration
1. Granular Carbon
The heat required for granular carbon regeneration is shown in Figure
3-67. The heat required for the furnace, afterburner and steam is
about 7,600 Btu/lb of carbon regenerated. Furnaces used in carbon
regeneration systems can be equipped with waste heat recovery systems.
2. Powdered Carbon
Difficulty with regeneration has been the major factor limiting the use-
' 13
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0. 15
II II
DIGESTION
TEMPERATURE:
95°F
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80
ANAEROBIC DIGESTER HEAT REQUIREMENTS FOR
PRIMARY PLUS WASTE ACTIVATED SLUDGE
5-15
FIGURE 5-4
-------
fulness of powdered activated carbon in the treatment of wastewaters.
There are at least three alternate systems of powdered carbon regener-
ation under development: (1) fluidized bed furnace, (2) wet air
oxidation, and (3) transport system. None of these three systems
has been used in a full scale municipal wastewater treatment plant.
The estimated fuel requirements shown in Figure 5-5 are based on fluid-
ized bed furnace pilot studies and information from manufacturers and
must be used with caution.
Some estimates indicate that the wet air oxidation regeneration system
used in the bio-physical process may be self sustaining except for start-
up and shutdown periods. Fuel requirements for the transport regener-
ation system may be higher than shown in Figure 5-5.
Ion Exchange Regenerant Renewal
The regeneration of clinoptilolite beds, used for the removal of ammonium
ions from wastewater, produces a regenerant solution with a high concen-
tration of ammonia. Ammonium can be removed from the regenerant solution
and the regenerant reused. Energy requirements for regenerant renewal
by air stripping are shown in Figure 3-70; requirements for the steam
stripping method are shown in Figure 3-71.
UTILIZATION OF ANAEROBIC DIGESTER GAS
Digester gas can be used for on-site generation of electricity and/or for
any in-plant purpose requiring fuel. Digester gas could also be used off-
site in a natural gas supply system. Off-site use of digester gas will
usually require treatment to remove trace impurities such as hydrogen sul-
fide and moisture; in most cases the heat value of the digester gas must
5-16
-------
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oc
1
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9
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2 34 56789 2 34 56789 2
1,000 10,000 100,000
X
3456 789
1,000,000
POWDERED ACTIVATED CARBON REGENERATED, Ib/day
HEAT REQUIREMENTS
POWDERED ACTIVATED CARBON REGENERATION
FIGURE 5-5
5-17
-------
be increased by removal of carbon dioxide before it could be used in a
natural gas system. In-plant energy requirements for primary and secondary
treatment always exceed the energy available from digester gas; therefore,
the remainder of this section is devoted to on-site use as fuel in internal
combustion (1C) engines. A schematic of a typical system to utilize di-
gester gas in an 1C engine is shown in Figure 5-6. As indicated in this
figure the engine could be coupled to a generator, blower or pump.
Gas produced by anaerobic digestion is about two-thirds methane and one-
third carbon dioxide with relatively small amounts of water, hydrogen sul-
fide, ammonia and other gases also present. The heat value of the gas
varies from one plant to another but is typically about 600 Btu/scf.
In some installations the gas is used directly from the digester while
in others water and hydrogen sulfide are removed to protect engines and
other equipment.
Gas Production
One of the most important design criterion that must be selected is the
volume of gas produced per unit of organic material destroyed in the di-
gester. An earlier EPA report on energy4 used 17.5 scf gas produced
per Ib of VS destroyed in the digester (This was based largely on data
from treatment plants in the City of Cincinnati). The Water Pollution
Control Federation manual on sewage treatment plant design gives 15
scf/lb VS destroyed. Data collected from operating plants during this
study indicates that 17 to 18 scf/lb VS destroyed is not routinely ob-
tained even at some well operated facilities and much lower values are
reported in some presumably well operated plants. Therefore, 15 scf/lb
VS destroyed is recommended for sizing typical digester gas utilization
systems.
5-18
-------
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CD CC
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m
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5-19
FIGURE 5-6
-------
The amount of sludge produced in a wastewater treatment plant, and the
VS content of the sludge, varies with the influent suspended solids concen-
tration, the BOD and type and efficiency of the biological treatment pro-
cess. The following sludge quantities used in Chapter 3 are based on a
review of data from several sources and are considered representative of
typical primary and activated sludge plants:
Sludge Solids
(lb/mil gal)
Sludge Type
Primary
Waste Activated
TOTAL
Total
1,151 ,
945
2,096
Volatile
690 (
756 (
1,446
(60%)
(80%)
A review of the literature and data collected from operating plants indi-
cates that about 50 percent of the volatile solids are destroyed by an-
aerobic digestion and that the gas produced has a heat value of about 600
Btu/scf.
These criteria give the following estimates for gas and heat available
from anaerobic digestion:
Primary
Sludge
5,175
1,105,000
Waste
Activated
Sludge
5,670
3,402,000
Total
10,845
6,507,000
Gas Produced, scf/ mil gal
Heat Available, Btu/ mil gal 3,105,000
For planning purposes, and in the absence of more specific information, it
may be assumed that about 6.5 mil Btu are available from gas produced
by anaerobic digestion of primary and conventional activated sludge treat-
ment of one million gallons of wastewater.
5-20
-------
Gas Utilization
Diesel or gas 1C engines can be used to drive electric generators, air
blowers or pumps in a wastewater treatment plant.
Diesel engines operate on fuel oil that is ignited entirely by the heat
resulting from the compression of the air supplied for combustion. Gas-
Diesel engines operate on a combustible gas (anaerobic digester gas in
this case) as primary fuel; the ignition of the digester gas is accomplished
by the injection of a small amount of pilot fuel oil. Commonly 8 to 10
percent fuel oil is required to operate a dual fuel engine. Dual fuel
Diesel engines are equipped to operate on fuel oil only or as a gas-Diesel.
Fuel oil is normally used in the alternate fuel system for dual fuel engines
in a wastewater treatment plant; however, it is possible to equip this
type of engine to also operate on natural gas or propane.
s
/
A gas engine is an 1C engine that operates on a combustible gas fuel (an-
aerobic digester gas in this case) that is ignited by an electric spark.
Natural gas or propane could be used as an alternate source of fuel in
a gas engine.
There are many variations in engine design, and auxiliary equipment re-
quired, for these two basic engine types. The operating speed and turbo-
charging are basic differences between engines supplied by different manu-
facturers. These variations in engine types result in equipment cost and
operation and maintenance cost variations.
The EPA Report assumes that work can be produced by an 1C engine operating
on digester gas at the rate of 1 hp-hr per 7000 Btu (since 1 hp-hr = 2547
Btu, the assumed efficiency is 36.4 percent). The efficiency of engines
5-21
-------
varies depending on the basic engine design and method of operation. In
general, low speed, turbo-charged or dual fuel engines require less fuel
per hp-hr than higher speed naturally aspirated engines. However, capital
costs are greater for the more efficient engines. Fuel required at an
1C engine-generator set efficiency of 30 percent is about 11,400 Btu/kwh.
The use of heat recovery equipment will increase the overall efficiency.
Heat recovery from 1C engines has been used successfully for many years
particularly with large slow speed engines. Waste heat that is recovered
is most often used for digester and/or space heating. The waste heat could
be used for any application requiring hot water or low pressure steam.
Typical heat recovery rates in percent of fuel supplied to the engine are:
jacket water, 18 to 20 percent; exhaust, 10 to 13 percent; combination
of both jacket water and exhaust heat recovery, 20 to 33 percent. This
recovered heat added to the 30 to 37 percent efficiency of the engine re-
sults in a total thermal efficiency ranging between 50 and 70 percent.
One generally used method of recovering jacket water heat is through ebul-
lient cooling, that is, raising the jacket water temperature to just above
the boiling point (215° to 220°F) and collecting the steam in an external
separator. The low pressure steam thus produced may be used for digester
heating, sludge drying, building heating or other purposes. Exhaust heat
is typically recovered by use of combination exhaust silencer and heat
recovery boilers. In some installations the jacket water and exhaust heat
are recovered in a single combined unit.
Table 5-3 is a summary of gas, heat and power available for various size
treatment plants based on the following criteria:
5-22
-------
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5-23
-------
1 Total dry solids to digester = 2,096 Ib/mil gal and VS = 1,446
Ib/mil gal from primary and conventional activated sludge treat-
ment.
2. Fifty percent of VS destroyed by digestion.
3. Digester gas produced = 15 scf/lb VS destroyed.
4. Heat available = 600 Btu/scf gas or 9,000 Btu/lb VS destroyed.
5. 1C engine efficiency =36.4 percent (7,000 Btu/hp-hr)
6. Engine-generator efficiency = 30 percent (11,400 Btu/hp-hr)
Cost Estimates-Digester Gas Utilization
Construction costs in this section include all elements of construction
cost a contract bidder would normally encounter in furnishing a complete
facility. Construction costs include materials, labor, equipment, elec-
trical, normal excavation and contractor overhead and profit. Construction
costs do not include costs for land, engineering, legal, fiscal and
administrative services or interest during construction. Equipment
costs were obtained through quotes from various suppliers and manufac-
turers. Construction costs include allowances for the following: over-
head and profit (25 percent), equipment installation (35 percent), elec-
trical (15 percent), piping and miscellaneous items (15 percent) and,
other site work and contingency (15 percent). Operating and mainte-
nance is broken down into three categories: (1) operating and mainte-
nance labor in hr/yr, (2) materials and supplies in $l,000/yr, and
(3) energy in kwh/yr or Btu/yr.
Estimated construction costs to clean and store digester gas are shown
in Figure 5-7; operation and maintenance data are shown in Figures 5-8
5-9, and 5-10. Hydrogen sulfide (H2S) can be removed from digester gas
by treatment in a chemical scrubbing system using sodium hypochlorite or
5-24
-------
GAS STORED - 1,000 cu ft
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w
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ES
5
10
2 3456789
100 1,000
2 3 456789
10,000
DIGESTER GAS CLEANED AND COMPRESSED, scfm
DIGESTER GAS CLEANING AND STORAGE
CONSTRUCTION COSTS
FIGURE 5-7
5-25
-------
DC
§
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10,000
9
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1,000
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89 2 3456789 2 34567BS
100 1'000 °'C
DIGESTER GAS CLEANED AND STORED, scfm
DIGESTER GAS CLEANING AND STORAGE
0 & M LABOR REQUIREMENTS
FIGURE 5-8
5-26
-------
1,000
2
3:
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DIGESTER GAS CLEANED AND STORED, scfm
DIGESTER GAS CLEANING AND STORAGE
MAINTENANCE MATERIAL COSTS
FIGURE 5-9
5-27
-------
(0
n
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DIGESTER GAS CLEANED AND STORED, SCfm
DIGESTER GAS CLEANING AND STORAGE
ENERGY REQUIREMENTS
FIGURE 5-10
5-28
-------
other oxidizing agents. Construction costs for scrubbing with NaOCl in
a packed tower include on-site hypochlorite generation. Operating and
maintenace costs for this type of scrubbing system assume the removal of
1,000 ppm H2S from the digester gas. It is possible to use activated car-
bon for H2S removal but the carbon must be regenerated with steam. Chemical
scrubbing systems appear to be more economical and simpler to operate. It
-may be possible to use other chemicals, or other sources of hypochlor.ite, to
furnish less expensive scrubbing systems than shown herein. Iron sponge
scrubbers have been installed in some treatment plants. Construction costs.
for cleaning and storing digester gas are greatly influenced by the storage
capacity provided. The storage capacity used in these estimates is based on
one sphere per plant.
Estimated construction costs for 600 rpm JC engines equipped with heat
recovery and alternate fuel systems are shown in Figure 5-11; operation
and maintenance estimates are shown in Figures 5-12, 5-13 and 5-14. These
ost curves include data for both dual fuel and gas engines. Operation
and maintenance costs "are greatly affected by the alternate fuel consumed.
Propane alternate fuel systems are more costly than fuel oil systems; how-
ever, gas engines that would require propane are less costly than dual
fuel engines that require fuel oil. Dual fuel engines require about 10
percent fuel oil on an average annual basis. Gas engines could operate
without using any alternate fuel. However, for these estimates, it is
assumed that 10 percent propane would be consumed. Propane would have
to be used (or at least paid for) to obtain contracts for a firm supply.
Construction costs for complete systems to generate electricity with di-
gester gas are shown in Figure 5-15; operation and maintenance data are
shown in Figures 5-16, 5-17, and 5-18. These costs are for a system as
shown in Figure 5-6.
5-29
-------
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1C ENGINE, hp
INTERNAL COMBUSTION ENGINE
CONSTRUCTION COSTS
600 rpm engine with heat
recovery and alternate fuel system
5-30
FIGURE 5-11
-------
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1C ENGINE, hp
INTERNAL COMBUSTION ENGINE
0 a M LABOR REQUIREMENTS
600 rpm engine with heat
recovery and alternate fuel system
5-31
-------
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1000 10,000
1C ENGINE, hp
INTERNAL COMBUSTION ENGINE
MAINTENANCE MATERIAL COSTS
600 rpm engine with heat
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FIGURE 5-13
5-32
-------
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1C ENGINE, hp
INTERNAL COMBUSTION ENGINE
ALTERNATE FUEL REQUIREMENTS
600 rpm engine with heat
recovery and alternate fuel system
5-33
FIGURE 5-14
-------
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100 .000
PLANT CAPACITY , mgd
DIGESTER GAS UTILIZATION SYSTEM
CONSTRUCTION COSTS
Complete electricity generation system
as shown in Figure 5-6
5-34
FIGURE 5-15
-------
(£
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J 9
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10
PLANT CAPACITY, mgd
3 456789
100
DIGESTER GAS UTILIZATION SYSTEM
0 a M LABOR REQUIREMENTS
Complete system for electricity generation as shown
in Figure 5-6
5-35
FIGURE 5-16
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to
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3456789 2 3486^89
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PLANT CAPACITY, mgd
100
DIGESTER GAS UTILIZATION SYSTEM
MAINTENANCE MATERIAL COSTS
Complete system for electricity generation
as shown in Figure 5-6
FIGURE 5-17
5-36
-------
OQ
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DIGESTER GAS UTILIZATION SYSTEM
ENERGY REQUIREMENTS
Complete system for electrical generation
as shown in Figure 5-6
FIGURE 5-18
5-37
-------
INCINERATION
Sludge incineration processes involve two steps: drying and combustion.
The drying step should not be confused with preliminary dewatering. De-
watering, usually by mechanical means, precedes the incineration process
in most systems. The drying and combustion process consists of raising
the temperature of the feed sludge to 212°F, evaporating water from the
sludge and increasing the temperature of the dried sludge volatiles to
the ignition point. Various types of incineration systems are available
including (1) multiple hearth furnace, (2) fluidized bed furnace, (3)
cyclonic reactors, and (4) electric furnace.
Multiple Hearth Furnace
A multiple hearth furnace consists of a circular steel shell surrounding
a number of solid refractory hearths and a central rotating shaft to which
rabble arms are attached. When burning a normal load of sludge a multiple
hearth furnace provides three rather distinct zones:
1. Two or more upper hearth on which most of the free moisture is evaporated.
2. Two or more intermediate hearths on which sludge burns at temperatures
exceeding 1500°F.
3. A bottom hearth that serves as an ash cooling zone by giving up heat to
the cooler incoming air.
During evaporation of moisture in the first zone the sludge temperature
is not raised higher than about 140°F. At this temperature no significant
5-38
-------
quantity of volatile matter is driven off, and hence no obnoxious odors
are produced. Exhaust gases need not be raised to 1400°F in an afterburner
to destroy odors. Distillation of volatiles from sludge containing 75
percent moisture does not occur until 80-90 percent of the water has been
driven off and, by this time, the sludge is down far enough in the inciner-
ator to encounter gases hot enough to burn the volatiles. Generally, when
fuel is required to maintain combustion in a multiple hearth furnace, a
gas outlet temperature above 900°F indicates too much fuel is being burned.
Construction cost estimates for multiple hearth incineration are shown
in Figure 5-19; operation and maintenace data are shown in Figures 5-20 and
5-21. Energy requirements are given in Figures 3-111, 3-112 and 3-113.
Fluidized Bed Furnace
A fluidized bed furnace is a vertical cylindrical vessel with a grid in
the lower section to support a bed of graded silica sand. Dewatered sludge
is injected above the grid and combustion air flows upward at a pressure
of 3.5 to 5.0 psi, fluidizing the mixture of hot sludge and sand. Suffi-
cient air is used to keep the sand in suspension but not to carry it out
of the reactor. The quantity of excess air is maintained at 20 to 25 per-
cent to minimize fuel costs. The heat reservoir provided by the sand bed
also enables start-up times to be reduced when the unit is shut down for
relatively short periods. An air preheater can be used to reduce fuel
costs. However, since air preheaters can represent 15 percent of the
fluidized bed furnace cost, a careful economic analysis is required to
determine its feasibility for a given situation.
Exhaust gases are usually scrubbed with treatment plant effluent and ash
solids are separated from the liquid in a hydrocyclone. An oxygen analyzer
in the stack controls air feed and a temperature recorder controls the
auxiliary fuel feed rate.
5-39
-------
PLANT CAPACITY, mgd
S
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WET SLUDGE FEED, Ib/hr
MULTIPLE HEARTH INCINERATION
CONSTRUCTION COST
Design and Operation Assumptions:
Loading rate =6 Ib/sq ft/hr
Sludge: Primary + WAS sludge =16% solids
FIGURE 5-19
5-40
-------
PLANT CAPACITY, mgd
c
§
E
100,000
9
8
7
6
5
4
3
2
10,000
9
8
7
6
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10,000
2 3456 789
100,000
WET SLUDGE FEED, Ib/hr
MULTIPLE HEARTH INCINERATION
0 &M REQUIREMENTS
Design and Operation Assumptions:
Loading rate = 6 Ib/sq ft/hr
Sludge: Primary ( WAS sludge >16% solids
FIGURE 5-20
5-41
-------
PLANT CAPACITY, mgd
fi
2:
~5
a
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t-
ut
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1,000,000
8
7
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34567 89 2 34567 89 2 34 5 6 7 B 3
1,000 10,000 100,000
WET SLUDGE FEED, Ib/hr
MULTIPLE HEARTH INCINERATION
MAINTENANCE MATERIAL COSTS
Design and Operation Assumptions:
Loading rate * 6 Ib/sq ft/hr
Sludge: Primary + WAS sludge =16% solids
FIGURE 5-21
5-42
-------
Cycl oni c Reactor^
Cyclonic reactors are designed for sludge disposal in smaller wastewater
treatment plants. In a cyclonic reactor high velocity air, preheated
with combustion gases from a burner, is introduced tangentially into
a cylindrical combustion chamber. Concentrated sludge solids are sprayed
radially towards the intensely heated walls of the combustion chamber.
Combustion takes place rapidly so that no material adheres to the walls
and the ash residue is carried off in the cyclonic flow and passes out
of the reactor.
The components of this sludge combustion system are very similar to
those used in a fludized bed system. Degritted, thickened primary plus
activated sludge is pumped to a centrifuge. The dewatered cake drops
into a hopper and is subsequently pumped into the cyclonic reactor with
a small amount of compressed air. These reactors process combined pri-
mary plus secondary sludge at nominal rates up to 100 to 130 Ib dry
solids per hour.
Electrically Heated Furnace
An electrically heated furnace uses infrared lamps for its heat source. The
lamps are high temperature tungsten filament quartz lamps with an average
life expectancy of 5000 hr at rated voltage. Because the heat is trans-
ferred by radiation rather than conduction or convection, the air is
not heated and combustion air requirements are reduced. The dewatered
sludge is conveyed through the furnace by a high temperature belt con-
veyor which carries the sludge through a drying zone and then into a com-
bustion zone. In the combustion zone, mounted just above the belt, is a
battery of infrared lamps which initiates and maintains the combustion.
The belt then discharges the ash into a hopper at the end of the machine.
The lamps and end seals are cooled by drawing outside air through the
cooling air ducts. This preheated air is then used as combustion air is
then exhausted through a wet gas scrubber or necessary air pollution equip-
ment.
5-43
-------
Although natural gas or oil may be a cheaper source of heat than electricity,
other savings associated with the infrared system may offset higher fuel
costs. Electric furnaces may be particularly attractive for small plants
and applications requiring intermittent operation. The incinerator can
be brought from ambient temperature to 1,600°F to 1,800°F within one hour.
This system also shows potential for the regeneration of activated carbon.
A 50 Ib/hr unit is in operation for carbon regeneration in an industrial
application in Baton Rouge, Louisiana.
Incineration Heat Requirements and Waste Heat Recovery
Incineration of sewage sludge may require auxiliary fuel to sustain com-
bustion depending on the sludge moisture and volatile solids content. The
relationship between auxiliary fuel required and sludge solids concentration
is shown in Figure 5-22 for primary and primary plus WAS. These curves in-
dicate that incineration is self sustaining at sludge solids concentrations
of about 26 percent for primary sludge and 23 percent for primary plus WAS.
Incineration will always require some fuel because of startup requirements.
Also, fuel may be required for afterburner emissions control equipment. Al-
though incineration will always be a net consumer of fuel because of these
requirements, the process is not necessarily a net consumer of energy. In-
cineration of sludge produces heat that can be recovered as steam and reused.
Incineration of high solids sludge can produce more energy in waste heat
(recovered as steam) than is required in auxiliary fuel (natural gas or fuel
oil).
Determining the net heat recovered from incinerators normally requires
a detailed analysis of the system heat inputs., and heat Tosses. Heat inputs
are combustion of sludge and auxiliary fuel, if any is used. Heat losses
include latent heat of free moisture and moisture of combustion, sensible
heat of flue gases and ash leaving the system, and furnace losses.
5-44
-------
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20 40 60
SLUDGE SOLIDS, % BY WEIGHT
80
ASSUMPTIONS:
10,000 Btu/lb VS
AUXILARY HEAT REQUIRED TO SUSTAIN
COMBUSTION OF SLUDGE
5-45
FIGURE 5-22
-------
In the following discussion recovered heat is calculated as the actual
heat recovered from incinerator or afterburner flue gases by heat exchange
equipment. Net heat recovered is the excess energy remaining after all
system heat inputs and energy requirements have been deducted from the
recovered heat. This analysis of heat recovered is independent of the
type of incinerator used for combustion of sludge because only the combus-
tion products or flue gases are considered. The concept of heat recovery
used herein assumes that a separate heat exchanger following the incinera-
tor is used to extract heat from the gases leaving the stack of the incinera-
tor or afterburner.
The temperature at which gases enter the heat exchange equipment is the
initial temperature and the temperature of gases leaving the heat exchanger
is the final temperature. The quantity of heat recovered from the flue
gases is dependent on the initial and final temperatures and is given by
the following equation:
HR = CF
! - T2) W
(5-5)
where
HR
CP
TI
T2
W
heat recovered, Btu/hr
specific heat of exhaust gases, Btu/lb-°F
initial temperature of flue gases, °F
final temperature of flue gases, °F
mass flow of flue gases, Ib/hr
The following example illustrates the use of equation 5-5:
Given:
flue gas temperature 800°F
specific heat of flue gas 0.33 Btu/lb-°F
flue gas flow rate 4700 Ib/hr
fine! flue gas temperature
500°F
5-46
-------
Then:
HR = (0.33 Btu/lb-°F) (800-500°F) (4700 Ib/hr)
= 465,300 Btu/hr
Based on the sludge characteristics and operating conditions in Chapter
3, (see Table preceding Figure 3-111), the heat recovered from the in-
cineration of primary and waste activated sludge is shown in Figure 5-23.
The calculated flow rate and percent moisture of the flue gases are based
on stoichiometric equations and include 100 percent excess air.
The energy requirements for incineration in a multiple hearth furnace (not
including sludge dewatering) are shown in Figures 3-111 through 3-113. An
example of sludge incineration energy requirements and heat recovered in a
10 mgd plant is shown in Table 5-4.
The largest heat loss is from evaporating moisture contained in the sludge
and therefore incineration of drier (higher solids content) sludge results
in less auxiliary fuel use and more net heat recovered. Heat treatment of
sludge prior to dewatering may result in sludge solids concentrations in
the 25 to 40 percent range after dewatering. Heat recovered from inciner-
ation may also be used in a heat treatment system. Several municipal treat-
ment plants have recently been put into operation that incorporate inciner-
ation of high solids content sludge, waste heat recovery and heat treatment
in an integrated system. The costs and energy requirements of the complete
sludge treatment system should be analyzed for each application. Because
of their substantial energy and cost impacts, it is important to include
the requirements for treatment of high strength liquors and odorous gases
produced in heat treatment reactors. Heat treatment is discussed in more
detail in a following section in this chapter.
5-47
-------
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SEE TABLE PRECEDING FIGURE 3-111 FOR SLUDGE CHARACTERISTICS
HEAT RECOVERED FROM INCINERATION OF SLUDGE
5-40
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-------
Combustion Air Feed To Incinerator
Practical operation of an incinerator requires that air in excess of
theoretical requirements must be supplied to the combustion chamber.
This increases the opportunity of contact between fuel and oxygen which
is necessary if combustion is to proceed. Fluidized bed furnaces commonly
use less than 50 percent excess air over the stoichiometric amount of air
required in the combustion zone. Multiple hearth furnaces commonly use
100 percent excess air. Excess air in the 100 to 200 percent range is
undesirable because it wastes fuel. However, when the amount of excess
air is inadequate, only partial combustion occurs, resulting in the for-
mation of carbon monoxide, soot and odorous hydrocarbons in the stack gases.
Therefore, a closely controlled minimum excess air flow is desirable for
maximum thermal economy. The amount of excess air required varies with
the type of burning equipment, the nature of the sludge to be burned and the
disposition of the stack gases. The impact of use of excess air on auxiliary
fuel required for sludge incineration is shown in Figure 5-24. Increasing
exhaust gas temperature increases auxiliary fuel requirements.
Preheating combustion air reduces the auxiliary fuel required and affords
an increase in capacity for a given size reactor since the combustion gas
volume is used more effectively. It should be noted that preheat exchangers
require significant capital expenditures and are recommended only after a
complete economic evaluation of the process.
Incineration of Combined Sludge and Solid Waste
Incineration of sewage sludge and solid waste combined has been suggested
5-50
-------
10.0
~ 8.0
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T3
C
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as a means of reducing the auxiliary fuel required for combustion of sludge.
Co-incineration of 5 percent solids sludge mixed with solid wastes is being
practiced in a fluidized bed furnace at Franklin, Ohio.
The sludge to refuse ratio necessary to just sustain combustion is deter-
mined by calculating a heat balance for the particular sewage sludge in-
cinerated. The heat inputs are the sludge and the refuse while the heat
losses are estimated to be 1,800 to 2,500 Btu per pound of water evaporated
in a furnace.11 The quantity of refuse required to sustain combustion
shown in Figure 5-25 was determined with the following assumptions:
Heat value of sludge:
Heat value of solid waste
Moisture in solid waste
Heat required to evaporate
water in furnace:
10,000 Btu/lb VS
4,750 Btu/lb
25 percent
2,100 Btu/lb water
Using these assumptions, sludge with 5 percent TS and 70 percent VS requires
at least 28 percent refuse to sustain combustion.
PYROLYSIS
Pyrolysis is a process in which organic material is decomposed at high
temperature in an oxygen deficient environment. The action, causing an
irreversible chemical change, produces three types of products: gas,
oil and char (solid residue). Water vapor is also produced, usually in
relatively large amounts depending on the initial moisture content of the
materials being pyrolysed. Residence time, temperature and pressure in
the reactor are controlled to produce various combinations and compositions
of the products. Two general types of pyrolysis processes may be used.
The first, true pyrolysis, involves applying all required heat external
5-52
-------
T-60
SLUDGE MOISTURE CONTENT, PERCENT
ASSUMPTIONS:
HEAT VALUE OF SLUDGE 10.000 Btu/lb VS
HEAT VALUE OF REFUSE 4750 Btu/lb
MOISTURE IN SOLID WASTE 25%
HEAT REQUIRED TO EVAPORATE WATER IN FURNACE 2100 Btu/lb WATER
COMBUSTION OF SLUDGE AND SOLID WASTE
(RELATIONSHIPS REQUIRED TO SUSTAIN COMBUSTION)
FIGURE 5-25
5-53
-------
to the reaction chamber. The other, sometimes called partial combustion
and gasification, involves the addition of small amounts of air or oxygen
directly into the reactor. The oxygen sustains combustion of a portion
of the reactor contents which in turn produces the heat required to dry
and pyrolyse the remainder of the contents.
Pyrolysis of municipal refuse and of sewage sludge has been considered
as a means for ultimate disposal of wastes for several years.
The
results of various studies and pilot programs indicate that if the moisture
content of a sludge is below 70 to 75 percent, enough heat can be generated
by combustion of the oil and gases produced from the pyrolysis of sludge
for the process to be thermally sustaining. Pyrolysis of municipal refuse,
and combinations of refuse and wastewater sludges will provide energy in
excess of that required in the pyrolytic process.
14,16
Laboratory, pilot and full-scale demonstration systems for pyrolysis of
wastewater sludges have been tested but no full-scale systems are in con-
tinuous operation. Therefore, the data and energy recovery estimates pre-
sented in this section must be considered preliminary. The reader is cau-
tioned that the data and energy estimates presented should not be used
for design or even planning purposes without further verification. Pyrolysis
systems are in the developmental stages and additional information will
become available as research and development work and the operation of
full-scale plants progresses.
Table 5-5 is a summary of information for most of the pyrolysis systems
presently under investigation. The main by-products and status of develop-
ment for the systems are shown in this table. The systems which are fairly
well developed are described in the following pages.
5-54
-------
TABLE 5-5
MUNICIPAL SOLID WASTE ANPt SEWAGE SLUDGE
PYROLYSIS PROCESSES
Developer
Products
Pilot Plant Scale
First
Major Demonstration Plant
Monsanto Envlrochem Systems
Inc., St. Louis, Mo.
(Landgard)
Occidental Research Corp.
(formerly Garrett),
La Verne, Calif.
Union Carbide Corp.,
New York, N. Y. (Purox)
c
N. Y. (Torrax)
BSP Division Envlrotech
Belmont, California
Jet Propulsion Laboratory,
California Institute of
Technology
Pasadena, California
DECO/Enterprlse Co.
Santa Ana, Calif.
Battelle Pacific Northwest
Laboratories, Rlchland,
Washington
Pyrolytic Systems, Inc.
Riverside, Calif.
DEVCO Management, Inc.
New York, N.Y.
Pollution Control, Ltd.
Copenhagen, Denmark
Urban Research & Development
Corp., East Granby, Conn.
FJEl,?Mucr )£eam> Ferrous
Metal, Wet Char, Glass
Aggregate
Pyrolytic Oil, Char, Glass.
Ferrous Metal, Nonferrous
Metal , Organlcs 1n Condensate
Fuel Gas, Slag
Steam (Fuel Gas)
Activated Carbon and Fuel
Gas
Fuel Gas and Oil
Steam (or Fuel Gas)
Fuel Gas or Electric
Power
Fuel Gas
Fuel Gas
Slag, Fuel Gas
36 ton/day
4 ton/day
200 ton/day
3 ton/day
Initiai pilot plant
operated at 10,000
gpd - sewage
5 ton/day
2 ton/day, 150 ton/day
demonstration plant
under consideration
50 ton/day by late
1976
50 ton/day
5 ton/day
120 ton/day
1000 ton/day solid wastes
(Baltimore, MD) co-pyrolysis
considered
200 ton/day solid wastes;
start-up schedule for late
1976 (San Diego, CA)
Solid waste; scheduled for
co-pyrolysis. Pilot plant
still in operation late
1976 (S. Charleston, WV)
200 ton/day commercial plant
under construction in Europe
(Andco, Inc.)
145 ton/day co-pyrolysis
(Concord, CA) Cowlitz
County, Wash. - Planned
to be in operation by
1978.
1 mgd pilot plant 1n oper-
ation (Fountain Valley,
CA)
150 ton/day started in June
1976, solid waste and solid
waste/sludge (South Gate,
CA)
5-55
-------
Rotary Kiln Reactor
In this process shredded waste materials are heated indirectly by com-
busting a portion of the pyrolytic gases produced. The remaining gases
are burned to produce steam in a utility boiler. The char is not com-
busted and requires disposal, however, it does have characteristics simi-
lar to some activat£jlJ^LrJiQ05_JuaLd eventually may be usable. The reactor
is a refractory-lined, rotary kiln; temperatures in the outlet from the
reactor reach 1,800°F. Residue discharged from the kiln is water-quenched
and then treated by flotation to separate the char from metal and glass
wastes. The off-gases from the reactor are drawn into a waste gas burner
where they are burned in air. The hot exhaust gases from the burner pass
through a water-tube boiler and then through a final cooler and air pollu-
tion control equipment. Operating on municipal solid wastes, the process
will produce slightly less than 2.5 tons of steam per ton of waste.
.
Vertical Shaft Reactor
The vertical shaft reactor system is a gasification or partial combustion
process which maximizes gas production. Pure oxygen is used in one com-
mercially available system and air is used in another. In the system using
oxygen, coarsely unshredded waste materials from which ferrous metals have
been removed are charged into the top of a vertical shaft furnace. Hot
combustion gases, essentially free of oxygen, rise through the furnace
and pyrolyse the descending wastes into fuel gas, oil and additional char.
The resulting gaseous mixture rises further, drying the incoming wastes.
Water and oil are condensed from the gaseous stream which is then cleaned
for use. The condensed oil is returned to the furnace for combustion and
further production of gas. The end result is a clean-burning fuel with a
heat value of about 300 to 500 Btu/scf produced at a rate of about 7.5
million Btu/ton of solid waste. This system will receive unprocessed trash
and, as a result of the high combustion temperature of the char, produce a
molten metal and glass slag. The slag is water-quenched and reportedly is
suitable for use as a construction fill material.
5-56
-------
A variation of this process uses air, not pure oxygen, to support combustion.
Char is combusted to provide the heat necessary for pyrolysis. The result is
a diluted fuel gas with a low heating value (120-150 Btu/scf) best utilized
by combustion on-site to produce steam.
Unprocessed wastes are fed to the primary reactor and are pyrolysed with the
heat from burning char as in the pure oxygen system. The pyrolytic gases
then flow through a secondary combustion chamber where they are completely
combusted with air. The resulting hot exhaust gases flow through a waste
heat boiler, a final cooler and air pollution control component before being
discharged to atmosphere. A portion of the hot gas from the secondary com-
bustion chamber is recycled and used to preheat incoming combustion air to
the primary reactor.
Another process that utilizes a vertical shaft reactor produces oil as its
main product. A finely divided, organic feed is supplied to the pyrolysis
reactor. Dividing is accomplished in a two-stage shredding operation which
also reduces the inorganic content of raw refuse through air classification
and screening to less than 4 percent by weight. The process, using the finely
divided feed, permits flash pyrolysis at atmospheric pressure for maximum
oil production. Discharge from the reactor goes first to a char separator
and then to a gas-liquid separator where gases and water are separated from
the oil. The relatively small amounts of char and gases produced are recycled
to produce heat for the reaction. The pyrolytic oil produced has a heating
value of about 10,500 Btu/lb and about 0.2 tons of oil are produced per ton
of solid waste processed. This oil is best utilized by blending with No.
6 fuel oil for use in utility boilers and has the advantage of being storable
and transportable.
5-57
-------
Multiple Hearth Furnace Reactor
Research and development work has been conducted on using multiple hearth fur-
naces, similar in design to conventional sludge incinerators, for pyrolysis
of wastewater sludges and municipal solid wastes. Shredded and classified
solid wastes and dewatered sludge are fed to the furnace either in a mixture
or separately with the wetter sludge fed higher in the furnace. Recirculated
hot shaft cooling air and supplemental outside combustion are fed to the
lower hearths to sustain partial combustion of the wastes circulating own
through the furnace. Fuel gas produced through the pyrolysis reaction is
then burned in a high temperature afterburner. The resulting heat can be
used in a waste heat boiler to produce high pressure steam. It may also be
possible to burn the fuel gases directly in a boiler. Char from the process
is not used but, because it has some fuel value, it may be usable as an in-
dustrial fuel. Multiple hearth furnaces, when fitted with flexible control
systems and operated properly, allow all the char to be burned.
The multiple hearth process offers the following advantages: (1) usable
in much smaller plants than most other pyrolysis systems, (2) employs modi-
fications of well developed sludge incineration equipment, (3) produces
high temperature gases without raising temperatures in the solid phase to
the slagging point, and (4) conversion from existing conventional sludge
incineration systems is a relatively simple procedure. Disadvantages include:
(1) fuel value of the char is not used, (2) high temperature fuel gases
must be used on-site, and (3) incoming solid wastes must be well classified
if solid wastes are used at all.
It is estimated that this process will produce between 2 and 2.5 tons of
steam from one ton of a 2:1 mixture of municipal solid waste and sludge.
5-58
-------
Horizontal Shaft Reactor
This process is actually a complete sewage treatment system employing
pyrolysis as one element. Screened, degritted raw sewage is mixed with
powdered activated carbon in a two-stage adsorption and settling system.
Activated carbon is added to the second stage mixing tank and settled in
the second stage settling basin. A mixture of partially exhausted carbon
and sludge is then transferred to the primary mixing tank and mixed with
incoming sewage. Sludge from the primary settling basin is dewatered,
flash dried and transferred to a rotary kiln or calciner. In the kiln the
carbon-sludge mixture is pryolysed to produce gas and a carbon-char mixture.
The gas has a fuel value of 350 to 400 Btu/cu ft. Steam is added to the
carbon-char mixture in the kiln to produce activated carbon for recycling
to the secondary mixing tank. Waste heat from the kiln is used in the
flash dryer and pryolytic gases can be burned to heat the kiln and to pro-
duce steam.
A 10,000 gpd unit has been tested17 and a 1 mgd pilot plant began operation
in August 1976. The process may be an alternative to existing methods of
wastewater treatment and sludge disposal; however, results of ongoing tests
must be evaluated before operating efficiencies and costs can be developed.
Heat Recovery
Analyses of available excess heat for some of these systems have been
presented for pyrolysis of solid wastes.14'16 An analysis has also been
presented for the pyrolysis of sludge using a rotary kiln reactor. The
following estimates for pyrolysis of refuse and sludge combined are
based on assumptions presented in the references. Estimates are
provided for two types of systems only, however, they should be
representative of most pyrolysis systems since the main interest is in
a heat balance for the overall concept and not in the unit heating values
for an individual product. Process differences result in variations
5-59
-------
in the composition and quantities of fuel produced, but should result
in relatively minor variations in net heat output. Thermodynamically,
the main difference between the two systems is whether or not the char
is combusted. The estimates show that considerable heating value is
lost by wasting the combustible portion of the char.
The assumptions used in calculating excess heat are shown in Table 5-6.
Estimated heat balance for inputs of 50 percent sludge and 50 percent
refuse, and for sludge alone, for the two systems are shown in Tables
5-7 and 5-8. A municipal sludge with a moisture content of 70 percent,
a volatile fraction of 70 percent and a high heating value of 7,000
Btu/lb was used. Values for pyrolysis of refuse alone were taken from
the references noted in the tables. Calculations for inputs of other
refuse to sludge ratios result in the curves shown in Figures 5-26 and
5-27. The refuse to sludge ratio for a typical residential community
is in the range of 10:1 to 15:1 on a dry solids basis and 3:1 to 8:1
on a wet solids basis, indicating that more than enough refuse is gene-
rally available for mixing with sludge to operate the process without
the need for an external energy source.
Heat recovery percentages are, in general, higher for the pure oxygen sys-
tem because the combustible part of the char is burned to provide process
heat. Other variations in heat losses between the two systems are due
to process differences. These calculations estimate that both systems
would probably be self-sustaining using a typical municipal sludge as
fuel but that no appreciable amount of usable excess heat could be ex-
pected. Sludge with a moisture content below about 65 percent, corres-
ponding to a filter-pressed sludge, will provide some excess heat; as
the moisture content increases above 75 percent, external heat must
be added to the process. There are enough variations in energy bal-
ances for different conditions that complete calculation should be made
for any application being considered.
5-60
-------
TABLE 5-6
ASSUMPTIONS USED
FOR CALCULATION OF EXCESS HEAT
Refuse
Moisture
Higher Heating Value
25% by weight
4750 Btu/lb
SIudge
Moisture
Solids
Volatile fraction
Higher Heating Value
70% by weight
30% by weight
70%
7000 Btu/lb solids
Carbonaceous (combustible) fraction of char
Refuse
Sludge
Higher Heating Value
10% of weight
14% of solids
13,000 Btu/lb
Other Assumptions
Input temp
Flue gas temp
Latent & sensible
heat for gases &
residue (% of total
heat input)
Fuel gas uses
Electrical energy
required
Rotary Kiln
Reactor System
60°F
500°F
17.2%
Vertical Shaft
Reactor System
60°F
200°F
11.2%
rr , - 792,000 Btu/ton input
65 kwh/ton input 120 kwh/ton input
5-61
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5-63
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3.0
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5-64
-------
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VERTICAL SHAFT REACTOR PURE OXYGEN PYROLYSIS SYSTEM
FIGURE 5-27
5-65
-------
INCINERATION VERSUS PYROLYSIS
Pyrolysis appears to have several advantages over incineration. For
example, some pyrolysis processes can convert wastes to storable, trans-
portable fuels such as fuel gas or oil while incineration only produces
heat that must be converted to steam. Air pollution is not as severe
a problem in pyrolysis systems because the volume of stack gases and
the quantity of particulates in the stack gases are less.
On the other hand, pyrolysis is essentially still in the developmental
stage and, with few exceptions, viable commercial systems are not readily
available. Most of the pyrolytic fuel gases have relatively low heat
values and the pyrolytic oil is corrosive, requiring it to be mixed
with other fuel oil for best results.
The construction and operating costs for most pyrolysis systems are
much more uncertain than for incineration. Reliable cost data for pyroly-
sis systems will not be available until significant operating experience
is developed from the ongoing and planned demonstration projects.
HEAT TREATMENT OF WASTEMATER SLUDGES
Heat treatment comprises several related processes in which sludges
are heated for conditioning prior to dewatering or for stabilization
prior to disposal. All the processes involve heating sludge for rela-
tively short periods of time in pressurized reactors. The reactor's
environment - temperature, pressure, residence time and oxygen content -
is selected based on the desired degree of sludge conditioning or sta-
bilization. As the temperature and amount of available oxygen are
5-6£
-------
increased a greater amount of stabilization or oxidation takes place.
Heat treatment processes are divided into two main categories depending
on the desired results: thermal conditioning and wet oxidation.
Thermal Conditioning
Thermal conditioning is used to condition sludge for subsequent dewater-
ing. Sewage sludges, particularly biological sludges, are normally
difficult to dewater and some form of conditioning to aid the dewatering
processes is required. Conditioning is often accomplished by adding
coagulating chemicals such as lime, ferric chloride and cationic polymers
to the sludge prior to a mechanical dewatering process. Thermal con-
ditioning on the other hand uses heat to change the physical and chemical
natures of the sludge. A dewaterable sludge is thus produced without
the addition of chemicals.
Under heat and pressure in a reactor, bound water and intercellular
water are released from the sludge and much of the smaller and more
hydrated particulate matter is solubilized. The result is a mixture
of relatively innocuous, sterile particulate matter and a liquid. The
two phases are easily separated after discharge by decantation and me-
chanical dewatering processes. The dewatered solids are inoffensive
and can be used as soil conditioner. The liquid phase is highly colored,
often has a very offensive odor and has a BOD ranging between 3,000
and 15,000 mg/1.
For thermal conditioning of most municipal sludges, reactor temperatures
and pressures range from about 300° to 500°F and 100 to 700 psi, respectively.
Residence time in the reactor is usually about 30 to 45 minutes at design
flow. A primary purpose in pressurizing the reactor is to prevent the
liquid contents from flashing to steam at the high temperatures involved.
Air may be added to the system to assist with heat transfer and to par-
tially oxidize the sludge.
5-67
-------
Wet Oxidation
This process oxidizes organic materials in the sludge to ash. Wet oxi-
dation is similar to thermal conditioning in that sludge is heated in
a pressurized reactor, but it's purpose is to stabilize the sludge
rather than condition it for dewatering. This requires an increase
in reactor temperatures and pressures to a range from about 450 to 700 F
and 400 to 3,000 psi, respectively. The reactor's environment is selected
based on the characteristics of the sludge and the degree of oxidation
desired. Air is added to the reactor to supply the oxygen needed by
the chemical reactions taking place. The degree of oxidation of the
sludge can be controlled and can range up to over 95 percent of the
influent COD for some sludges. This is equivalent to results attain-
able in dry incineration processes, but in wet oxidation, temperatures
are much lower, fly ash is not a problem and the sludge need not be
dewatered before being oxidized.
Energy Requirements
In order to operate any heat treatment process, the temperature of the
incoming sludge must be raised to the selected reactor temperature.
To heat one gallon of sludge from 50°F to a thermal conditioning tem-
perature of 350°F requires 2,500 Btu and to raise the temperature to
700°F for complete oxidation requires about 5500 Btu. Thus a 10 mgd
treatment plant producing 10 tons per day of sludge requires approxi-
mately 150 mil Btu/day for thermal conditioning and 320 mil Btu/day
for wet oxidation. These values are net heats required by the sludge
and must be increased to reflect the efficiency of the heat generating
and transferring system and losses from the overall system. The actual
energy input is, therefore, almost double the above figures.
5-68
-------
Heat exchangers are incorporated into the processes to capture the heat
from the treated sludge in the reactor outlet. In this manner, incoming
sludge is heated to within 40 to 50°F of the reactor temperature with
a corresponding drop in required input energy. With an efficient heat
exchange system, about 420 Btu/gal is required to reach the reactor
temperature and, accounting for system inefficiencies, a total energy
input of about 900 Btu/gal is required. This heat is normally supplied
by injecting steam into the reactor.
Heat to generate the steam is usually produced in gas or oil-fired
boilers. However, when sludge incinerators follow thermal conditioning
plants, waste heat boilers deriving heat from the incinerator stack
gases have been used successfully to provide all the required heat.
Injection of air into the reactor allows heat-producing oxidation re-
actions to occur. In those thermal conditioning systems where air is
supplied, oxidation of about 5 to 10 percent of the volatile solids
takes place. Assuming typical wastewater sludges and a heat value of
10,000 Btu/lb of volatile solids, the required heat input is reduced
from 900 Btu/gal to between 500 and 700 Btu/gal. This reduction in
required heat is accompanied, however, by an increase in electrical
energy needed to compress the air. Table 5-9 shows the heat input re-
quired for thermal conditioning of several sludges and Figures 3-89
through 3-92 show the annual heat requirements for the same sludges.
By increasing the degree of oxidation, as is done in wet oxidation,
to 20 to 30 percent of the volatile solids content, enough heat is pro-
duced in the reactor to offset the need for supplementary steam. Steam
is then needed only to initially heat the system to the reaction tem-
perature. Further increase in the degree of oxidation produces excess
heat which may be used to generate steam or hot water for other uses.
5-69
-------
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5-70
-------
Or, hot, pressurized off-gases from the reactor can be expanded through a
turbine to drive process equipment or an electrical generator.
The recoverable energy from a wet oxidation system treating the primary and
waste activated sludge mixture described in Table 5-9 can yield almost 16
horsepower per gpm of capacity. Comparing this recoverable energy with the
energy required to operate the system shows that the output very nearly
equals input. Of course, the energy balance will change for different
sludges and system conditions, but in all systems a large amount of the in-
put energy is recoverable.
Sidestreams
Besides the direct energy requirements ,of heat treatment, other related
areas of energy use must be considered. These are the treatment of
the high-strength liquors produced in the reactor and the treatment
of odorous gases emanating from air-water separators, storage tanks,
and subsequent dewatering processes. Often, costs and energy require-
ments for these operations are incorrectly excluded when making feasi-
bility studies involving the processes. Their impacts on energy con-
sumption can be substantial.
Strong liquors from thermal conditioning processes which include super-
natant from decanting operations and filtrate or centrate from dewater-.
ing operations, must be treated before discharge. These liquors are
usually treated in one of three ways: (1) separate biological treat-
ment (aerobic or anaerobic) perhaps followed by adsorption on activated
carbon, (2) recycled directly back to the primary or secondary treat-
ment plant, or (3) biological pretreatment and then recycled back
to the main treatment plant for additional treatment. Because of its
high-strength (BOD of 3,000 to 15,000 mg/1 and suspended solids of 10,000
to 20,000 mg/1) and even though the volume is low (0.4 to 0.8 percent
5-71
-------
of the inflow to the treatment plant), the increased load due to re-
cycling or separately treating can be quite significant. Recycling
strong liquor directly to an activated sludge plant can increase the
air requirement, and consequently the energy requirement, by as much
as 30 percent.
Most of the various systems available to control concentrated process
odors also consume relatively large amounts of energy. The methods
most commonly used and most generally effective for controlling odors
from thermal treatment are high temperature incineration, adsorption
on activated carbon, and chemical scrubbing. Table 5-10 shows the re-
quirements for the three methods based on a typical 1,000 cfm odor con-
trol system. A concentrated gas stream of 1,000 cfm corresponds to
a thermal treatment plant size of 200 to 250 gpm or a sewage treatment
plant size of 50 to 60 mgd. The energy requirements developed for the
three methods represent the needs of complete odor control systems and
include requirements for collection of gases; ducting; fans; chemical
feeding, mixing, and storage equipment; automatic control systems; dis-
posal of removed and waste materials; and discharge of treated gases
as well as for odor removal itself.
The incineration or afterburning process considered consists of pre-
treatment by water scrubbing using treated effluent in a packed bed
and direct-flame incineration at 1,500°F with recovery of 40 percent
of the input heat. The carbon adsorption process includes prescrubbing
with effluent, dual-bed adsorption on activated carbon, regeneration
of carbon with low pressure steam, condensation of vapors, and inciner-
ation of the waste organic stream. The chemical scrubbing system uti-
lizes three stages of scrubbing in packed beds. The first two stages
use secondary effluent and a final stage uses a buffered, potassium
permanganate solution.
5-72
-------
TABLE 5-10
ENERGY CONSUMPTION FOR ODOR CONTROL SYSTEMS
Electrical Energy1
kwh/1000 cu ft
kwh/yr (1 mgd)2
kwh/yr (1 gpm)3
Fuel!
million Btu/1000 cu ft
million Btu/yr (1 mgd)2
million Btu/yr (1 gpm)3
Incineration
122
1285
321
36.8
387
97
Carbon
Adsorption
146
1540
385
1
11
2.7
Chemical
Scrubbing
146
1540
385
1Based on continuous operation.
21 mgd indicates approximate sewage treatment plant capacity.
31 gpm represents approximate thermal treatment plant capacity.
5-73
-------
HEAT PUMPS
Some of the heat in sewage effluent can be recovered through the use
of heat pumps. Since heat pumps operate on a refrigeration cycle their
components and circuit diagram are similar to a conventional refriger-
ation system. A refrigeration system operates in a cycle with the net
result being the absorption of some heat at a low temperature (at the
evaporator), the rejection of a larger amount at a higher temperature
(at the condenser), and a net amount of work done on the working sub-
stance or refrigerant (by the compressor). A heat pump provides rela-
tively cool temperatures at the evaporator (less than 45°F) and rela-
tively warm temperatures at the condenser (greater than 90°F). The
changeover from heating to cooling is permitted either by valves in
the refrigerant lines that effectively interchange the positions of
the evaporator and condenser or by valves in the lines of the fluid
that carry heat from source or to sink.
Heat pumps are classified by the type of heat source or heat sink and
the distribution fluid. For example, a heat pump that uses water for
a heat source or sink to condition air in a building is a water to air
heat pump. Some common types of heat pumps include the following:
Heat Source/Sink
Water
Water
Air
Air
Earth
Distribution Fluid
Water
Air
Air
Water
Air
The choice of heat pump depends on several factors such as location,
climate and application. The types of heat pumps best suited for ap-
plication in wastewater treatment plants include the first three listed
above: water to water, water to air and air to air.
5-74
-------
Water to air and water to water heat pumps may use sewage effluent for the
heat source or sink. The water to air heat pump can be used for space
heating or space cooling. With sewage effluent at 50°F, relatively high
efficiencies should be obtained in either cooling or heating operation.
No such application of a heat pump is known to exist at this time. How-
ever, a water to water heat pump is planned for the wastewater treatment
plant at Wilton, Maine. Its purpose is to extract heat from 50°F effluent
for heating sludge digester influent. The total energy supplied by the
heat pump will be 31 million Btu/yr with a coefficient of performance (COP)
of 2.8. The COP indicates the quantity of heat derived from a given heat
input. Figure 5-28 illustrates the varying output and COP that can be
expected for a heat pump operating at various wastewater temperatures
under the conditions at Wilton, Maine.
Heat pumps using the atmosphere as the source/sink are usually air to air
systems used for space heating and cooling. A typical performance curve
for such a heat pump on a heating cycle is shown in Figure 5-29. Curves
of this type are available from manufacturers for specific systems and
indicate the variability of the system COP and heating capacity as a func-
tion of the temperature of the heat source or outside air.
Also shown in Figure 5-29 is the heat loss of a typical structure. Be-
cause the heating capacity decreases with the outside air temperature
while the building heat requirements are increasing, a temperature is
reached which is defined as the system balance point. At this temperature
the heat pump capacity equals the heating requirements of the building.
For the example shown in Figure 5-29, the system balance point is 23°F.
If the outside air drops below this temperature, supplemental heating will
be required to maintain indoor design temperatures. The heat pump
capacity and COP curves terminate at a heat source temperature of 15°F
because this particular heat pump will not operate below that temperature.
Outside air temperature below 15°F will require the use of a backup system
to provide the entire heating load.
5-75
-------
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WASTEWATER TEMPERATURE, °F
HEAT PUMP OUTPUT BASED ON WILTON PLANT DESIGN
OPERATING CONDITIONS FOR VARIOUS EFFLUENT TEMPERATURES
FIGURE 5-28
5-76
-------
100
m
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TYPICAL PREFORMANCE CURVE
FIGURE 5-29
5-77
-------
Cost Estimates - Heat Pumps
The heat output capacity of the Wilton plant system is 320,000 Btu/hr
at the condenser, while the cooling capacity at the evaporator is 228,000
Btu/hr. The unit is basically a water chiller modified to withstand
the corrosive environment of chlorinated wastewater and will be a back-
up source of heat for digester influent. The primary digester heat
source in the Wilton plant is solar energy. It is expected that the
heat pump will only operate about 100 hr/yr.
Estimated construction costs for water to water heat pumps similar to
the Wilton installation are shown in Figure 5-30. Estimated operating
and maintenance data are shown in Figures 5-31 , 5-32 and 5-33. These
cost curves are also applicable to water to air heat pump systems.
Figure 5-34 shows the estimated construction cost for air to air heat
pump systems; operation and maintenance data are shown in Figures 5-35,
5-36 and 5-37.
SOLAR ENERGY USE IN WASTEWATER TREATMENT PLANTS
Solar energy may be used for space and process heating in wastewater
treatment plants through three different types of collector systems:
1. Active solar collection (water collectors)
2. Passive solar collectors (insulated translucent panels)
3 Atmospheric solar collection (to be used by heat pump outside coil).
The use of this type of system is discussed in the section on heat
pumps.
5-78
-------
to
8
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2 3456789 2 3456789 2
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3
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5
6 789
100,000
HEAT PUMP CAPACITY, thousand Btu/hr
WATER TO WATER/WATER TO AIR HEAT PUMPS
CONSTRUCTION COST
FIGURE 5-30
5-79
-------
of
s
10,000
9
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7
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1,000 10,000 100,000
HEAT PUMP CAPACITY, thousand Btu/nr
WATER TO WATER/WATER TO AIR HEAT PUMPS
0 & M LABOR REQUIREMENTS
5-80
FIGURE 5-31
-------
100,000
1
6
5
4
3
2
l_
£ 10,000
« §
AINTENANCE MATERIAL, doll
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100 1,000 10,000
5
6 789
100,000
HEAT PUMP CAPACITY, thousand Btu/hr
WATER TO WATER/WATER TO AIR HEAT PUMPS
MAINTENANCE MATERIAL COSTS
FIGURE 5-32
5-81
-------
100,000
a
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100,000
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HEAT PUMP CAPACITY, thousand Btu/hr
WATER TO WATER/WATER TO AIR HEAT PUMPS
ENERGY REQUIREMENTS
OPERATING CONDITIONS:
COP= 2.8
OUTSIDE TEMPERATURE=50°F
5-82
FIGURE 5-33
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FIGURE 5-35
5-84
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FIGURE 5-36
5-85
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FIGURE 5-37
5-86
-------
Solar Insolation
The solar energy, termed insolation or irradiation, available at a parti-
cular location on the earth varies greatly throughout the year due to
atmospheric absorption and angle of the sun above the horizon. This
variation in the United States is illustrated in Figure 5-38. The daily
average variation in solar energy at three cities in California is shown
in Figure 5-39. Data for solar insolation curves are compiled by the
U. S. Weather Bureau and are available in several publications.1*'19
Active Solar Collection
The sun's energy can be collected and utilized in various ways. The
most common use of solar energy is by active solar collection. This
type of system in general is composed of solar collector, heat storage
system, heat exchanger and various pipes and pumps for circulating a
working fluid which transfers the heat absorbed at the collector to
the storage device. Common working fluids used are water, a water and
glycol mixture and air. Typical storage devices are a large tank of
water, a bed of rocks or a combination of the two. The working fluid
is pumped through the collectors to the storage device throughout the
day as long as the temperature of the fluid coming from the collector
is higher than the temperature of the fluid in storage. For space and
water heating purposes, fluid is circulated from storage through a heat
exchanger and back to storage. A schematic of the general concept for
space and water heating is shown in Figure 5-40.
The most common type of collectors are "flat plate" collectors. Other
types of collectors such as concentrating and sun following collectors
have been used and are available. Concentrating collectors use reflec-
tive devices or lenses to focus a large amount of solar radiation upon
5-87
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5-88
-------
2500
JAN FEB MAR APR MAY JUNE JUL AUG ' SEPT ' OCT ' NOV ' DEC
MONTH
DAILY AVERAGE VARIATION IN SOLAR ENERGY
AT THREE CITIES IN CALIFORNIA
FIGURE 5-39
5-89
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FIGURE 5-40
-------
a relatively small collection area. These devices normally require
accurate tracking systems so that the sun's rays always strike the con-
centrating equipment at the proper angle. Because only direct radia-
tion can be concentrated these devices are not very effective on cloudy
days when diffuse radiation prevails. Due to many variables such as
the amount of solar insolation, heat losses from reflection and radi-
ation, differences in glazing surfaces and fluctuations in ambient tem-
perature, collectors operate at continuously varying efficiencies through-
out the day.
Materials with a fairly high heat capacity are used to store heat during
periods when the sun is not available, such as night heating or periods
of cloudiness. Water, with a heat capacity of 1.0 Btu/lb/°F, is often
used to store heat where freezing is not a problem. Water is usually
the fluid circulated in collectors. A concrete or steel tank is the
most common storage device. Rocks have a specific heat of about 0.2
Btu/lb/°F and are also used, especially if the circulating fluid is
air. Another device for storing heat, presently being investigated,
is the heat of fusion for melting and freezing salt hydrates. These
materials can store far greater quantities of heat for a given weight
and volume of material (90 to 118 Btu/lb at 96 to 122°F).
Passive Solar Collection
Passive solar collectors consist of translucent panels of glass, fiber-
glass, or plastic normally located in the wall or roof of a building.
Solar energy passing through these panels is absorbed by surfaces and
objects below. This concept was used in the design of the wastewater
treatment plant in Wilton, Maine for the passive collection of solar
energy into the clarifier and onto darkly painted masonry and concrete
surfaces for the retention of heat in a building.20 The heat col-
lected from such a system depends on solar energy available and size
5-91
-------
of panels. For example, panels of the type used at the Wilton plant
cover 960 sq ft, have a light transmission factor of 45 percent and a
heat loss factor of 0.24 Btu/°F/sq ft/hr.
Example - Solar System For Space Heating
Determination of the actual useful amount of solar radiation collected is a
somewhat involved procedure. The continuously changing solar input to the
collector plus the constantly varying collection efficiency suggest that an
hourly or even minute by minute calculation for the entire year is necessary
for accurate determination of the solar energy collected Computer programs
are available to do such calculations. A simplified approach is used in this
example by averaging the daily variations into monthly variations.
The treatment plant location used in this example is 40 deg latitude in the
vicinity of Detroit, Michigan. Solar insolation data for this location, col-
lector output and heat requirements for 2,000 sq ft floor area are summarized
in Table 5-11. These data show that about 2,700 sq ft of collector area are
required to heat a 2,000 sq ft building in December and January and virtually
no heating is required in the summer.
Solar System Costs
Costs for solar systems vary considerably at the present time. For custom^
designed systems, costs as high as $80 per square foot have been reported.
Commercial flat plate collectors ranging from $4 to $15/sq ft, or more, are
available. The less expensive units have no glazing or cover glass and are
generally used for swimming pool heating. The more expensive units are applied
to space and process heating and cooling. The glazed collectors generally
5-92
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range from $12 to $15/sq ft. The costs for other system components
and installation increases the cost to about $25 sq ft for a complete
flat plate collector system.
21
Passive solar collector costs vary from about $5 to $7/sq ft, depending
on the size of each panel, thickness and material. Installation costs
are about $1.50/sq ft.
ENERGY CONSERVATI5N IN EXISTING WASTEHATER TREATMENT FACILITIES - INVOLVING
NO CAPITAL OUTLAYS
Reductions in energy use in existing treatment plants can be accomplished
by several methods including: (1) adjusting pumping and air flow rates
during periods of low flow, (2) optimizing the timing of sludge treat-
ment processes such as thermal conditioning, sludge drying, and incine-
ration, (3) varying the solids retention time in activated sludge
processes, and (4) scheduling the use of various forms of in-plant
(recovered) energy to minimize the demand for outside energy. The methods
can vary from modifying equipment to installing new equipment, simply
turning off unneeded lights, keeping air filters clean and changing work-
ing hours for plant personnel.
Pumping Adjustments
One of the prime users of energy in most plants is pumping. Typically,
the pumps using the majority of the total pumping energyinfluent,
effluent and recirculation pumps-are of the centrifugal type. Centri-
fugal pumps normally have characteristics similar to those shown in
Figure 5-41 which indicates that, for a given pump and impeller, as
the pumping head is increased both flow and power consumption are de-
creased. As shown in the figure, partially closing the pump discharge
5-94
-------
NON-CLOG SEWAGE
PUMP-U50 RPM
PUMP EFFICIENCY
HW = PUMP HORSEPOWER
SYSTEM CURVE
WITH THROTTLED
POINT "A"
-SYSTEM CURVE
HEAD LOSS
2000 2400 2800 3200 3600 4000
CAPACITY-6PM
EFFECTS OF THROTTLING AND IMPELLER TRIMMING
ON POWER REQUIREMENTS FOR PUMPS
5-95
FIGURE 5-41
-------
valve creates an artificial head which results in moving the pumping
point on the curve from "A" to "B". Such adjustments can be made to
cover slack periods or the initial phases of plant operation when in-
flows are low. Some caution must be exercised so that valves are not
closed so far that they plug, that line velocities are not reduced to
the point where solids will deposit, or that in cycling operations the
pumps don't just operate longer at reduced efficiency with no savings
in energy.
Several other methods are available to reduce pumping energy including:
changes to the pump, changes in the number of pumps and changes in pump
speed. If a pump is to be operated at a reduced capacity for a consi-
derable period of time, energy can be saved by installing a smaller
impeller in the same pump. As shown in Figure 5-41 by point "C", this
method reduces flow, as does throttling, but reduces power consumption
to a greater extent than throttling. A comparison based on the case
shown in Figure 5-41 is given in the following tabulation:
Comparison of Energy Required for Pumping
at Reduced Flows
Condition
Initial Design (Point A)
Throttled Discharge (Point B)
Smaller Impeller (Point C)
* Corrected for motor efficiency based on 75 hp motor
Flow
gpm
2800
1600
1600
Pump
Efficiency
Percent
78
70
67
Pump
Input Power
hp
60
48
30
Motor
Input Power*
kw
49
40
25
5-96
-------
Perhaps the most common method to vary pumping rate and conserve pumping
energy for larger plants is control or adjustment of pump speed. Speed can
be controlled in several ways depending on the pumping conditions and the de-
sire for automation. Simple, semi-permanent methods involve changing pulley
sizes for belt-drives or changing motors to lower speed designs. As
the desire for flexibility increases, drives using manually adjustable
pulley and belt systems, two speed motors and various manually control-
led electronic drives can be employed. These methods require only that
operating personnel turn a handcrank, push a button or turn a knob to
adjust pump speed.
For centrifugal pumps, the effect of a change in speed on pumping energy
is illustrated in Figure 5-42. Note that reducing pump speed rather
than trimming impeller diameter allows the use of the more efficient,
full-size impeller and at the same time provides for a quick, easy way
to increase pumping capacity should that become necessary. Operation
at lower speed also results in longer pump life.
The next step in flexibility and control is variable speed pumping.
In true variable speed pumping, pump speed is regulated automatically
by either varying motor speed or by the use of a variable speed drive
between the pump and motor. Speed is controlled to pace the pump flow
in accordance with a selected process variable such as wet well level
or discharge pressure. This method offers great flexibility and po-
tential for energy savings. However, efficiency loss in the variable
speed drive, initial cost of the drive and controller and increased
maintenance cost of drive and controller must be taken into account
and may offset any anticipated savings in energy. As with most energy-
saving proposals, life-cycle cost and true benefits must be analyzed.
Not all pumps exhibit the characteristics indicated above for centri-
fugal pumps. Propeller or axial flow pumps normally exhibit the charac-
teristic of an increasing power requirement for an increase in discharge
5-97
-------
112
400 800 1200 1600 2000 2400 2800 3200 3600 4000
CAPACITY -GPM
EFFECT OF SPEED REDUCTION ON
POWER REQUIREMENTS FOR PUMPS
FIGURE 5-42
5-98
-------
head. Power requirements for positive displacement pumps vary almost
in direct proportion to discharge pressure.
Energy savings can best be realized from these pumping systems, parti-
cularly from positive displacement systems, by varying pump speed.
Nearly all of the speed control methods discussed above for centrifugal
pumps may be used effectively with positive displacement pumps. Small
positive displacement pumps, such as those used for chemical feeding,
sludge pumping and activated carbon transfer are often equipped with
built-in, calibrated means to control either the length or timing of
their pumping strokes. Adjustments to these types of pumps are made
easily and quickly, either manually or automatically. An adjustable
timer can be used to control the percent of time the pump operates.
Energy savings can also be accomplished by sharing the pumping load
among several pumps in a system. If multiple units are available, only
the number of pumps necessary to handle the required volume need be
operated at any time. Turn-down is easily accomplished by starting
and stopping pumps.
An energy-saving concept often overlooked for both centrifugal and
positive displacement pumping systems is the use of internal combustion
engines equipped with adjustable or variable speed controls. Manual
control of an engine's speed requires only an adjustment to the throttle
or governor mounted on the engine. Automatic control requires instal-
lation of a speed controller costing only a few hundred dollars.
Pump Maintenance and Operation
Besides the adjustments to pumps discussed above, several factors re-
lated to operation and maintenance of pumping systems affect energy
consumption. The plant maintenance program should provide for periodic
5-99
-------
checks of the systems' efficiency and corrections should be made where
indicated. Some items to check are:
1. Partial clogging or closures in valves, pipelines and pumps.
2. Wear on pump impellers and casings increasing clearances between
fixed and rotating parts thereby decreasing efficiency. Installa-
tion or replacement of wear rings or adjustment of the impeller
setting is all that may be required to regain original efficiencies.
3. Improper adjustment of packing causing binding of the pump shaft.
Power requirements can be increased up to 5 percent and shaft wear
can be greatly accelerated by improper adjustment of packing.
4. Improper settings for start-stop controls causing too frequent cy-
cling of pumps and resulting in increased power costs as well as in-
creased wear on the pumping system.
Another area of review for potential energy conservation is over-pumping
of sludge from settling basins. Over-pumping usually results in pumping
of sludge with an undesirably low solids content. In addition to in-
creasing the energy required to pump the sludge, there can be a chain
effect throughout the plant. Over-pumping often occurs during low-flow
periods and results either from a failure to reset the pumping cycle
to reflect the new flow or sludge production condition or from purposely
over-pumping to avoid any possibility of any septic sludge floating
on the basin surface.
The effects of pumping sludge with 4 percent solids versus 5 percent
solids include: (1) increase of 20 to 25 percent in initial pumping
5-100
-------
energy, (2) increased volume of sludge can affect loadings, efficien-
cies and energy requirements for thickeners, supernatant return pumps,
chemical feeding and mixing equipment, digester heating systems and
dewatering systems, and (3) adverse effects on digester gas production
and incinerator operation.
It should also be noted that under-pumping can result in loss of clari-
fier removal efficiency, increased odors, and additional loading on
secondary treatment processes. Pumping must, therefore, be optimized
under a variety of conditions for each plant.
Aeration System Adjustments
Aeration or oxygenation in secondary treatment is, like pumping, one
of the greatest users of energy in treatment plants. Frequently, energy
required for aeration in activated sludge plants far exceeds all other
uses in the plants. Because of this, the possibility of savings deserves
a great deal of attention by operating personnel.
In conventional diffused-air plants, the primary energy user is the
blower. Like pumps, blowers can be either centrifugal or positive dis-
placement (centrifugal blowers are used almost exclusively in large
plants and are used quite frequently in small plants).
Centrifugal blowers can be controlled in much the same way as discussed
above for centrifugal pumps. Air flow can be controlled by partial
closure of a throttling valve on the blower discharge, by changing im-
peller design, or by changing speed. One of the easiest, most efficient
and most common ways, however, is by adjustment of the valve on the
suction side of the blower. This method reduces energy consumption
more than throttling the discharge valve for the same reduction in air
5-101
-------
flow. Figure 5-43 illustrates the effects of the two methods of thrott-
ling to achieve the same reduced flow. Note that since the restriction
in the inlet to the blower changes the pressure and volume of the inlet
stream, point "C" representing the operating condition with a throttled
suction does not fall on the original characteristics curve. Because
most blower installations already provide the necessary valving, the
only expenditures are for operating labor.
Control of the suction valve can be easily and inexpensively automated
and controlled from a program matching historic daily variation in flow
or oxygen requirements, from the influent flow meter or from dissolved
oxygen monitors in the aeration tanks.
Air flow and hence energy consumption also can be controlled for posi-
tive displacement blowers. Here, as with positive displacement pumps,
control of speed or the use of several units are the only ways to ef-
fectively reduce energy consumption.
Related to savings through control of air flow are savings through main-
tenance. Blowers, too, have bearings, seals, clearances, etc. which
must be properly maintained to minimize energy use. Likewise, air fil-
ters and diffusers must be kept clean. Dirty filters and diffusers
can account for increased pressure drops of up to 20 percent for'some
systems.
Effects of Solids Retention Time on Overall Energy Utilization
Management of the use of electrical energy at treatment plants by mani-
pulating the solids retention time (SRT) results in a tradeoff between
aeration basin power and additional sludge production. The amount of
5-102
-------
SYSTEM CURVE WITH
THROTTLED DISCHARGE
NORMAL SYSTEM
OPERATING POINTS:
A. DESIGN POINT
B. THROTTLED DISCHARGE
C. THROTTLED SUCTION
200 300
400 500 600 700
ACTUAL CFM ENTERING
800 900 1000
COMPRESSOR INLET
1100 1200
EFFECTS OF THROTTLING ON POWER
REQUIREMENTS FOR CENTRIFUGAL BLOWERS
FIGURE 5-43
5-103
-------
energy used in the aeration basin is a function of the oxygen demand
in the aeration basin. Figure 5-44 shows the theoretical oxygen re-
quirement per pound of BOD versus SRT. The practical limits of SRT
vary from 3 days to about 15 days and by varying the SRT, the energy
requirements may vary more than 20 percent.
Sludge production increases with decreasing SRT. Figure 5-45 shows
the theoretical sludge production per pound of BOD removed. The
waste sludge quantity is predicated on an effluent solids concentration
of 20 mg/1. Over the 3 to 15 day SRT range, the amount of waste acti-
vated sludge varies from 0.58 Ib/lb BOD5 to 0.42 Ib/lb BOD5.
The energy associated with disposal of the solids depends on the sludge
treatment and disposal methods used. For instance, if the sludge is to
be digested, the net plant energy utilization would not change since
oxygen demand not satisfied in the aeration basin would need to be satis-
fied in the aerobic digester. On the other hand, if the sludge produced
is to be treated in an energy-intensive system prior to disposal, it
may be prudent to increase the SRT to reduce solids production. The
reverse situation would apply to a low energy use disposal system.
It is presumed that any modification of the SRT would not affect the
effluent quality to such a degree that less than the required quality
results; that nitrification in the aeration basin must be considered;
and the turn-down capability of the aeration equipment is such that power
utilization is a direct function of oxygen demand. In practice, these
limitations can be met; however, there are few plants having the
capability to do so.
5-104
-------
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5-105
FIGURE 5-44
-------
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To exemplify the magnitude of the energy use for varying SRT values
an example is presented in Table 5-12 for waste activated sludge which
is thickened, dewatered and hauled to disposal. The example is a moderate
energy use system and, without consideration of secondary energy require-
ments for polymer, indicates that a short SRT should be maintained.
Intermittent Operation of Sludge Treatment Processes
The following discussion considers the intermittent operation of three
sludge treatment processes: heat treatment, dewatering and incineration.
The discussion will center on energy implications, but will also consider
costs. The situations considered for the three processes are abbreviated
in detail from the analyses which should be made in actual situations.
In studies for actual cases, costs of constructing and operating sludge
storage tanks, variations in utility rate structures for changing de-
mands, labor required for clean-up after each operating cycle, and many
other items must also be reviewed in greater detail.
1. Heat Treatment - Energy requirements for heat treatment processes
have been summarized previously in this chapter. As noted, an in-
put heat energy of approximately 900 Btu/gal is required for thermal
conditioning. This figure varies as the process and reactor con-
ditions vary to the point where the process becomes energy-producing.
The energy requirements given represent the total heat input to
the boiler and reflect the overall efficiency of the system during
continuous operation at design capacity. The overall efficiency
takes into account the efficiency of the boiler and heat transfer
systems and the heat lost to atmosphere through radiation.
5-107
-------
TABLE 5-12
SOLIDS RETENTION TIME AND ENERGY USE
10 mgd SECONDARY PLANT
Influent to aeration - 945 Ib solids/mil gal
1300 Ib BOD/mil gal
SRT, days
Aerati on
Ib 02/lb BOD
Ib 02/day
0.96
12,480
1.14
14,820
15
1.22
15,860
WAS
Ib WAS/1b BOD 0.58
Ib WAS/yr 2,752,000
0.46
2,183,000
0.42
2,000,000
Energy Required, million kwh/yr
Aeration
Pumping
Air Flotation
Vacuum Filter
Haul
TOTAL
4.60
0.01
0,14
0.08
£.06.
4.89
5.40
0.01
0.11
0.07
0.05
5.64
5.80
0.01
0.10
0.06
0.04
6.01
5-108
-------
When a thermal conditioning system is operated intermittently, the
900 Btu/gal heat input is still required. In addition, however,
each time the operation is discontinued the system cools and must
be reheated on start-up. Since after cooling there is no heat out-
flow from the reactor to preheat the incoming sludge, the entire
heating load must be supplied from the boiler system. Approximately
260,000 Btu/gpm of system capacity is required for a high temperature,
wet oxidation plant. This indicates that a considerable amount
of excess heat energy must be expended if the schedule for inter-
mittent operation requires frequent cycling and points out that
from an energy-effectiveness standpoint operating cycles should
be as long as possible. In actual plant operation, this can be
done by operating continuously for two or three days at a time
rather than for one shift per day every day.
In underloaded plants, some partial offsetting of the requirement
for start-up energy can be realized by operating at full capacity
even though intermittently. Because the system operates at the
same temperature regardless of flow, heat is lost to the atmosphere
at a nearly constant rate and becomes a more significant portion
of the total heat required as the flow decreases. Figure 5-46 il-
lustrates the fraction of heat lost to the atmosphere by opera-
ting at different percentages of design capacity.
A decrease in the consumption of electrical energy is usually noted
for intermittent operation where no waste heat recovery is practiced.
This results primarily from the increase in efficiency of process
equipment as its size increases. Overall, the energy requirement
increases as the number of operating cycles increases.
The greatest potential for savings from intermittent operation is
in labor. The smaller the plant the greater the savings. Operating
5-109
-------
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750
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HEAT LOST THRU RADIATION
25
50
75
ACTUAL FLOW vs. DESIGN FLOW, percent
100
HEAT REQUIREMENT FOR THERMAL CONDITIONING SYSTEM
AT LESS THAN DESIGN FLOW
FIGURE 5-46
5-110
-------
labor accounts for over 60 percent of the total operation and main-
tenance costs for a 4 gpm, continuously operated plant. This figure
drops rapidly as plant size increases, but still amounts to over
25 percent for a 400 gpm plant. Estimated costs for continuous
and intermittent operation of a small plant treating a sludge flow
of 4 gpm are shown in Table 5-13. Treating the equivalent of 4
gpm (corresponding to a sewage flow of 1 mgd) of sludge during
five day shifts a week rather than continuously reduces the opera-
ting labor cost from $35,000 per year to $10,500 per year. Energy
costs for the same conditions increase from $5,100 per year to $9,800
per year. For an operating schedule of one shift per day, five
days per week, the intermittently operated plant will require a
capacity of approximately 17 gpm. The analysis in Table 5-13 in-
dicates that even with the increased energy consumption, cost for
operating the larger plant intermittently is much lower than that
for operating the smaller plant continuously. The difference be-
tween the two is reduced significantly, however, when amortized
construction costs are added to determine total annual costs.
Table 5-13 also shows a similar breakdown of costs for a 40 gpm
heat treatment plant (corresponding to a sewage flow of 10 mgd).
Here, again, energy requirements increase when the plant is operated
intermittently while the total operating costs continue to be lower.
At this size, however, amortized construction cost more than off-
sets the savings in operating cost making the total annual cost
of intermittent operation approximately 50 percent more than for
continuous operation.
This review of heat treatment system operation indicates that:
(1) The total costs for each system must be analyzed to determine
if intermittent operation is cost-effective and, if so, what inter
mittent schedule produces the minimum cost, (2) Intermittent
5-111
-------
TABLE 5-13
COMPARISON OF CONTINUOUS AND INTERMITTENT OPERATION
OF A HEAT TREATMENT PLANT
ITEM
Operating Labor
Maintenance Labor
Energy
Materials & Supplies
Total 0 & M
Cost per gallon
Construction Cost
Total Annual Cost
Cost per gallon
4
COST
1,2
1 mgd
10 mgd
Continuous Intermittent Continuous Intermittent"
$35,000
9,100
5,700
7,500
$10,500
2,600
9,800
2,300
$52,500
11,900
62,500
13,200
$24,900
5,200
96,000
6,500
57,300 25,200
1.64 0.72
48,300 59,200
105,600 84,400
3.00 2.40
140,100 132,600
0.40 0.38
100,200 238,800
240,300 371,400
0.69 1.06
Costs are in dollars/year.
2Based on sludge volume of 4 gpm per mgd.
^Operation 5 days per week, one shift per day.
"^Amortized at 7% for 15 years for continuous operation and at
7% for 20 years for intermittent operation.
5-112
-------
operation of new plants not yet operating near their design capa-
cities will normally be cost-effective based on operating costs
alone. Only detailed analyses can show if a plant should be over-
sized to allow intermittent operation at design flows, and (3)
As plant size increases the cost-to-size relationships change such
that possible benefits from intermittent operation are reduced.
2. Dewatering - Physical processes which are operated at or near am-
bient temperature are the most amenable to savings through inter-
mittent operation. Energy is used in these processes to drive mechani-
cal equipment which can be started and stopped without the energy
loss that occurs in processes operated at elevated temperatures.
Also, because the efficiency of mechanical and electrical equipment
usually increases as the size of the equipment increases, and equip-
ment operated near design capacity has greater efficiency, operating
intermittently at full-load results in greater overall system ef-
ficiency.
An example of a dewatering system consisting of chemical conditioning
and vacuum filtration is used to illustrate the potential for energy
savings from the dewatering processes. Table 5-14 shows the energy
requirements for 1 and 10 mgd plants operated intermittently and
continuously. The data shows that intermittent operation can reduce
energy consumption by approximately 45 percent for a 1 mgd plant
and by over 20 percent for a 10 mgd plant. As the size of the plant
increases, the saving continues to decrease, but at 100 mgd the
saving is still about 15 percent.
The total operating and maintenance costs for the above cases are
also reduced through intermittent operation. The savings are ap-
proximately 20 percent for both 1 and 10 mgd plants.
5-113
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3.
The summary of estimated costs as shown in Table 5-15 indicates
that additional construction costs offset the savings in operating
costs in a 1 mgd plant and the total annual costs are nearly the
same. In a 10 mgd, however, construction costs increase with in-
creasing capacity at such a rate that total annual cost for inter-
mittent operation is almost 15 percent greater than for continuous
operation.
Incineration - Incineration, like most physical and chemical pro-
cesses for treating sludge can be operated intermittently but, be-
cause of the high temperatures involved, there is generally no re-
duction in energy consumption unless the periods between running
cycles are quite long and/or waste heat recovery is employed. As
with heat treatment, energy consumption may actually increase for
intermittent operation.
Fuel requirements for incineration can be divided into three cate-
gories:
Auxiliary - fuel needed to assist with drying and combusting the
sludge;
Start-up - fuel required to heat the incinerator to operating
temperature at the beginning of each cycle; and
Maintenance - fuel need to maintain a desired temperature in
the incinerator when it is not burning sludge.
The amount of auxiliary fuel required depends primarily on the amount
of moisture and volatile material in the sludge as illustrated in
Figure 5-23. On a unit basis, it can be assumed nearly constant
whether the equipment is operated continuously or intermittently.
5-115
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5-116
-------
Requirements for start-up fuel are determined by the design of the
incinerator, the initial and final temperatures involved and the ;
heating time, while maintenance fuel requirements are set by the
design of the incinerator and the desired temperature. A trade
off between start-up and maintenance fuel requirements determines
the schedule of intermittent operation for a given set of conditions.
Since, on a per hour basis, requirements for start-up fuel are typi-
cally 5 to 10 times the requirements for maintenance fuel, and
heating and cooling times for incinerators are long, a wide variety
of conditions must be considered'in order to select the optimum
schedule. Whether to let the furnace cool at all during periods
when not in use or, if it is allowed to cool, how low to carry the
temperature must be determined for each proposed schedule.
An example of fuel requirements for incineration of a typical de-
watered sludge from a 5 mgd secondary treatment plant is summarized
in Table 5-16. It should be noted that this example serves only
as a comparison of several cases for one particular set of conditions.
The following conclusions are based on the conditions assumed for
this example: (1) continuous operation of a smaller incinerator
requires less fuel than intermittent operation of a larger incine-
rator handling the same quantity of sludge, (2) for frequent
cycling as in Case 2, less fuel will be used if incinerator operating
temperatures are maintained between cycles, and (3) as the time
between operating cycles increases as in Case 3, less fuel will
be used if the unit is allowed to cool all the way to ambient tem-
perature.
Table 5-17 shows the estimated costs for three of the cases presented
in Table 5-16. These estimates indicate that amortized construction
5-117
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TABLE 5-17
COST FOR CONTINUOUS AND
INTERMITTENT INCINERATION OF SLUDGE
Costss
dollars per year
Case1
Operating Cost2
Fuel
Electrical Energy
Labor
Materials & Supplies
Total 0 & M
Construction Cost3
Total Annual Cost
1
16,500
9,000
32,200
6,000
63,700
169,900
233,600
2A
18,700
6,800
24,900
3,300
53,700
349,200
402,900
3A
17,200
7,500
26,700
4,000
55,400
254,900
310,300
See Table 5-16 for description of cases
0 & M costs are based on:
Fuel = $3.00/million Btu
Electricity = $0.025/kwh
Labor = $7.00/hr
Amortized 20 year life and 7% interest
5-119
-------
costs far outweigh operating costs in all cases, and therefore,
continuous operation of small incinerators will result in lower
total cost than intermittent operation of a larger incinerator.
The cost estimates also indicate that the total energy consumption
fuel and electrical energy - is nearly constant for all cases.
This result is similar to most other sludge treatment processes
in that labor is the most significant part of operating cost.
5-120
-------
REFERENCES - CHAPTER 5
1.
ASHRAE Guide and Data Book, Fundamentals for 1965 and 1966 American
Society of Heating, Refrigerating and Alr-CondltlonKg Engineers, Inc
3. Ration of Wastewater Treatment Plants," WPCF Manual of Practice No. 11,
for Mun1c1pal Wastewater
5. Gilman, S. F., Hall, L.A., and Palmatier, E., "The Operating Cost of
ReS1dential Cooling Equipment." ASHVE Transactions, Vol 60! 1954.
Sc?entif?c
'" The
9. ASHRAE, Handbook and Product Directory 1973 System, Chapter 43, New York,
10. Sewage Treatment Plant Design," WPCF Manual of Practice No. 8, p. 232,
11. Loran, Bruno, I., "Burn That Sludge!" Water & Wastes Engineering, October
12. Folks, N. E "Pyrolysis as a Means of Sewage Sludge Disposal, "ASCE
Journal of Environmental Engineering Division, Aug! 1975.
13. Lewis, F. M. , "Thermodynamic Fundamentals for the Pyrolysis of Refuse "
Stanford Research Institute, May 1976. yyysis or Keruse,
14. Lewis, F. M., "Thermodynamic Fundamentals for the Pyrolysis of Refuse "
Stanford Research Institute, May 1976. Ceruse,
15' P^]cZ' DM-DH-/"."Enr?y from Munic1Pa1 Refuse: A Comparison of Ten
Processes," Professional Engineer, November 1975.
16' Kff'V' J- and I°c°s R' F" "Theal Processing of Municipal Solid
Waste for Resource and Energy Recovery," Ann Arbor Science, Michigan, 1976
5-121
-------
17 Humohrev, M. F., et al., "Carbon Wastewater Treatment Process",
paper presented at ASME Conference, July 29, 1974, ASME 74-ENA-46.
18. Duffie & Beckman, "Solar Energy Thermal Processes," Wiley & Sons, New
York, 1974.
19. Yellott, J. I., "Solar Energy Utilization for Heating and Cooling,"
NSF, U. S. Government Printing Office, 1974.
20. Water & Sewage Works, "Wastewater Plant Design Reduces Off-Site
Energy Needs," February 1976.
21 Clark, J. A., Seminar, "Solar Energy System for Heating and Cooling,"
California State University, Los Angeles, April 1976.
5-122
-------
CHAPTER 6
EXAMPLES - ENERGY REQUIREMENTS, RECOVERY AND RECYCLING
The purpose of this chapter is to illustrate the use of the curves and data
presented in Chapters 3, 4 and 5. It is important to recognize that the
analyses in this chapter are strictly in terms of energy utilization and
in no way endorse the cost effectiveness of treatment trains described.
The cost effectiveness of the alternative systems must be determined on a
case by case basis, where factors such as facility size, capital cost of
energy recovery systems, and labor costs are important.
Primary and secondary energy requirements are presented for each unit pro-
cess in 14 example treatment systems. A flow diagram and effluent quality
goals are given for each example system. Energy requirements, potential
alternate energy sources, and energy recovery and recycling methods that
might be used, are given in a table and also shown in a block diagram for
each example.
EXAMPLE 1 - TRICKLING FILTER (ROCK MEDIA)'WITH COARSE FILTRATION
This example is a 30 mgd plant in the Southern U.S. with high rate, rock
media, trickling filters followed by coarse filtration. Sludge is treated
by anaerobic digestion and digester gas is used as fuel for internal com-
bustion engines. Engines are direct coupled to pumps and also used to
generate electricity for motors and plant electrical equipment. Waste
heat from the engines is recovered as low pressure steam and used to supply
part of the digester heating requirement. The remainder of the digester
heating requirement is supplied by solar energy heat pump systems. Solar
energy is also used for building heating. It is assumed that raw sewage
and trickling filter pumping, and building heating and cooling energy re-
quirements can be reduced about 10 percent by conservation measures.
6-1
-------
Data in the table and bar chart for this example indicate total treatment
process requirements of 4.4 million kwh/yr and 33.8 billion Btu/yr. It can
be calculated, by the methods outlined in Chapter 5, that about 49.3 billion
Btu/yr is available in digester gas. Engines are direct coupled to pumps
to furnish the following requirements:
Thousand kwh/yr
Raw sewage
Trickling filter
Coarse filter
TOTAL
The remaining digester gas is used to generate 2.1 million kwh/yr of elec-
tricity for use as follows:
Preliminary treatment
Primary sedimentation
Secondary sedimentation
Chiorination
Gravity thickening
Anaerobic digestion
Sludge drying bed
Building cooling
TOTAL
This example system results in an excess of about 0.6 million kwh/yr which
could be used for on-site generation of hypochlorite, thus reducing the se-
condary energy requirement for chlorine.
Assuming 25 percent of the fuel used by the engines is recovered as waste
heat, the total waste heat recovered from the engines is 12.3 billion Btu/yr.
All of this recovered heat is used to heat the digesters. Assuming influent
sludge temperature of 60°F, the digesters require another 19.4 billion Btu/yr
for heating. In this example, half of this heat is supplied by heat pump
and the other half by solar energy.
6-2
-------
EXAMPLE 2 - ACTIVATED SLUDGE WITHOUT INCINERATION
This example is a 30 mgd activated sludge plant in the Southern U.S. using
anaerobic digestion for sludge treatment. The digester gas is used as fuel
for internal combustion engines which are direct coupled to pumps and also
used to generate electricity. Waste heat from the engines and solar energy
are used to heat the digesters.
Data in the table and bar chart for this example indicate total treatment
process primary energy requirements of 8.9 million kwh/yr and 33.8 billion
Btu/yr. About 71.2 billion Btu/yr is available in digester gas and this
is utilized as follows:
Engines direct coupled to pumps and blowers:
Thousand kwh/yr
Raw sewage pumping
Air flotation thickening
TOTAL
Electricity generated with digester gas:
Primary sedimentation
Aeration - mechanical
Anaerobic digestion
TOTAL
Thousand kwh/yr
30
4,400
438
41868"
As shown in the table for this example, an additional 1.8 million kwh/yr
must be supplied from outside sources. As in Example 1, all the waste heat
recovered from the engines (about 17.7 billion Btu/yr) is used to heat the
digesters, with the additional required 14 billion Btu/yr supplied by heat
pump and solar energy.
EXAMPLE 3 - ACTIVATED SLUDGE WITH INCINERATION
This example is a 30 mgd activated sludge plant in the Northern U.S. with
sludge disposal by incineration. Waste heat recovered from the incinerator,
6-3
-------
calculated by the n-ethods given in Chapter 5, Figure 5-24 result in 132
billion Btu/yr, This heat is used for electricity generation by a steam
turbine at the rate of 11,400 Btu/kwh (which is an efficiency of 32.8% -
this efficiency 'nay vary depending on the type of equipment used),
resulting in 13.2 million kwh/yr of electricity to furnish the following
requirements:
Raw sewage pump
Preliminary treatment
Primary sedimentation
Aeration - mechanical
Secondary sedimentation
Chiorination
Gravity thickening
Air flotation thickening
Vacuum Filter
Incineration
Building cooling
TOTAL
Thousand kwh/yr
420
102
30
4,400
250
290
8
1,250
630
1,300
6
8,686
This recovered energy supplies all the plant's electrical needs with an
excess of 4.5 million kwh/yr. Part of this excess could be used for on-
site generation of hypochlorite this reducing the secondary energy
requirements for chlorine.
The sludge disposal system in this example assumes thickening, vacuum
filtration and incineration of 16 percent solids. An alternative
sludge treatment system that is discussed in Chapter 5 uses waste heat
from the incinerator for heat treatment. This allows a drier sludge, in
the range of 30-45 percent solids, to be supplied to the incinerator and
may result in a lower total energy requirement than for the example
shown.
EXAMPLE 4 - EXTENDED AERATION
A one mgd plant in the Southern U.S. has little potential for energy
recovery and recycling. Total energy requirements could be reduced
through conservation methods and use of a solar energy system to supply
building heating requirements.
6-4
-------
EXAMPLE 5 - EXTENDED AERATION WITH SLOW SAND FILTER
This example is very similar to Example 4 with the addition of a slow sand
filter after the extended aeration activated sludge process.
EXAMPLE 6 - ACTIVATED SLUDGE WITH CHEMICAL CLARIFICATION
This example is very similar to Example 2 except that chemical clarification
and chemical sludge treatment are added and require additional energy. Chemi-
cal sludge treatment is by filter pressing and land disposal. Primary energy
for sludge digestion is higher than Example 2 because the plant is located
in Northern U.S. and more energy is required for digester heating.
EXAMPLE 7 - ACTIVATED SLUDGE WITH NITRIFICATION AND CHEMICAL CLARIFICATION
This example is similar to Example 6 with the addition of biological nitri-
fication. Total energy requirements are increased somewhat while recovery
and recycling potential from anaerobic digester gas utilization remains the
same.
EXAMPLE 8 - ACTIVATED SLUDGE - HIGHER THAN SECONDARY TREATMENT
The treatment system for this example includes conventional activated sludge
plus nitrification, chemical clarification with lime, filtration and carbon
adsorption. Biological sludges are treated by anaerobic digestion and lime
chemical sludge is recalcined and reused. Stack gas from the recalcining
furnace is scrubbed and compressed for use in the recarbonation process.
It may be possible to recover some of the waste heat from the recalcining
process for other in-plant uses, however, this alternative is not considered
here. Energy from the anaerobic digestion process is recovered and reused
as in the previous examples and waste heat from the carbon regeneration fur-
nace is converted to electricity by a steam turbine generator system.
6-5
-------
EXAMPLE 9 - INDEPENDENT PHYSICAL/CHEMICAL - SECONDARY TREATMENT
The treatment system for this example does not use biological processes.
Energy in the form of waste heat from the incinerator and carbon regenera-
tion process is recovered and reused by generation of electricity as dis-
cussed in Example 3. It may be possible to utilize waste heat from in-
cineration for heat treatment to increase solids concentration in the
sludge supply to the incinerator. This process may change the net energy
required somewhat.
EXAMPLE 10 - INDEPENDENT PHYSICAL/CHEMICAL - HIGHER THAN SECONDARY
TREATMENT
The treatment system in this example is similar to Example 9 with additional
unit operations to provide a higher degree of treatment resulting in higher
energy requirements than in Example 9. Recovery and recycling is limited
to generation of electricity utilizing steam recovered from the furnaces.
As in the previous examples utilizing sludge incineration, it may be
possible to produce a higher solids sludge by the use of heat treatment and
thereby change the net energy requirements somewhat.
EXAMPLE 11 - PONDS,
The treatment system in this example consists of an aerated pond followed
by chlorination. There is no potential for energy recovery or recycling,
however, it is assumed that a 10 percent savings in energy could be achieved
in raw sewage pumping and pond aeration system operation by conservation
techniques.
EXAMPLE 12 -' LAND TREATMENT BY INFILTRATION/PERCOLATION
This example is similar to Example 11 with land treatment by infiltration/
percolation following the aerated pond in place of chlorination. This
6-6
-------
system uses approximately 1.9 million kwh/yr less than Example 11 because
of reduced secondary energy requirements for chlorine production. However,
as in Example 11, there is no potential for energy recovery or recycling.
EXAMPLE 13 - LAND TREATMENT BY OVERLAND FLOW
This example is similar to Example 11 with the addition of land treatment
by overland flow. This adds 410,000 kwh/yr to the primary energy required
for treatment. All other energy considerations are identical to Example
11.
EXAMPLE 14 - LAND TREATMENT BY SOLID SET OR CENTER PIVOT
IRRIGATION
This example is similar to Example 11 with the addition of land treatment
by spray irrigation at an application rate of 0.33 inches per day. Two
alternatives are presented. The solid set system uses approximately 7
million kwh/yr less than the center pivot system, but neither one contains
any potential for energy recovery or recycling. As in Example 11, it is
assumed that energy conservation techniques will reduce energy requirements
by about 10 percent.
6-7
-------
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6-35
-------
-------
CHAPTER 7
ENERGY REQUIREMENTS FOR TREATMENT FACILITIES
GREATER THAN 100 MGD AND LESS THAN 1 MGD
The purpose of this chapter is to discuss energy requirements that are
unusual or unique for very large and very small treatment plants.
TREATMENT FACILITY CAPACITY LESS THAN 1 MGD
The requirements for small plants are important because, as shown by the
data in Chapter 2, there are many small plants in the U.S. Most of the
energy conservation measures described in Chapter 5 are more difficult
to implement in small plants. Small plants usually do not have an
operator on duty 24 hours per day. Also, skilled operation and
maintenance personnel (personnel that are required to obtain energy
savings through conservation) are often not available for small
facilities.
Anaerobic digester gas utilization and the use of waste heat from incin-
erators is not feasible in small plants. Engines and other necessary
equipment are not available for small capacity plants. The smallest
commercial multiple hearth furnace has a hearth area of 85 sq ft. How-
ever, heat recovery from sewage through the use of heat pumps is possible
even for very small plants.
Unit processes from Chapter 3 that are not usually applicable to treatment
facilities with a capacity less than 1 mgd include the following:
1. High purity oxygen activated sludge systems.
2. Two stage recarbonation.
7-1
-------
3. Heat Treatment.
4. Incineration.
5. Pyrolysis.
6. Lime recalcination.
TREATMENT FACILITIES WITH CAPACITIES GREATER THAN 100 MGD
Most of the unit processes presented in Chapter 3 are applicable to large
plants. Processes which would normally not be considered for large plants
include:
1. Low rate trickling filter.
2. Activated bio-filter.
3. Brush aeration oxidation ditch.
4. Aerated pond (as a primary treatment process).
5. Aerobic digestion.
The energy conservation and recycling methods discussed in Chapter 5 all
have the potential of more effective application in large plants.for the
following reasons:
1. Minor efficiency improvements can result in large savings.
2. Multiple unit pumps and aeration equipment offer more opportunity
to match design capacity and actual flows.
Recycling equipment for anaerobic digester gas and heat recovery systems
are available in large sizes which result in more efficient operation.
7-2
-------
CHAPTER 8
NATIONAL AND REGIONAL COST PROJECTIONS
INTRODUCTION
The purpose of Chapter 8 is to place the cost of energy in proper per-
spective with the other costs of wastewater treatment plant construction
and operation. Regional variability in the relative price of energy,
labor, construction, and consumables is important in a preliminary
evaluation of the cost-effectiveness of a particular alternative. This
chapter is divided into two major sections:
! National Cost Projections present the best estimates available for the
projected national costs of construction, operation and maintenance of
wastewater treatment plants.
2- Regional Cost Variation presents the current regional cost variations
for various cost categories that affect treatment plant construction
and operation.
The estimates and projections may serve as a guide in planning wastewater
treatment facilities, and should be considered preliminary to any present
value alternative cost-effectiveness comparisons such as those contained
in the following chapter. It is useful to know, for instance, at an early
stage in the planning process, that a high labor cost for a particular
municipality might offset in part the beneficial impact of a low energy
alternative that is labor intensive in its operation.
8-1
-------
NATIONAL COST PROJECTIONS
This section presents projections of national trends from 1975 to 1995 for
the costs that impact wastewater treatment facility construction, operation
and maintenance. Projections are presented for four cost categories:
(1) electrical energy, (2) labor, (3) construction, and (4) con-
sumables (as defined in Chapter 4). Government publications and reprints
of hearings concerned with future costs of energy, future energy require-
ments and future economic trends are a major source of reference for this
chapter.
Most projections are based on average percent increase of a cost index from
one year to the next. A base year is selected and then the cost of a given
item, such as electrical energy, is set at 100 for that year. For example,
if the base year is 1967 and the cost rose 7 percent in 1968, the index
for that year would be 1.07. If the cost rose 8 percent in 1969, the index
for 1969 would be: 1.07 x 1.08 = 1.1556, or about 1.16. The projections
presented in this chapter are computed in this fashion using cost indexing;
1975 is the base year and percent increase during 1975 - 1995 are computed.
The basis for cost indexes consists of specific costs of materials and/or
labor, if applicable, for a given sector of the economy. For example, a
construction index consists of costs for specific amounts of labor, con-
crete, steel, lumber and other items. The wholesale price index consists
of costs for specific amounts of certain commodities. The costs of in-
dividual items are then proportioned to derive an index.
Cost indexes are used in this report because they are designed to measure
changes and historically have proven to be fairly good indicators. How-
ever, they are not intended to measure absolute prices, and, in fact, some
real price changes cannot be measured such as improvements in quality,
8-2
-------
hidden discounts or improved delivery schedules.1 In addition, the pro-
jections of these cost indexes cannot be expected to give precise pre-
dictions, but only show the general trend in future costs based on
current knowledge of the economy.
Electrical Energy
»
The trend for the cost of electrical energy shown in Figure 8-1 was pro-
jected from the wholesale cost index for fuel and power published by
the Federal Energy Administration (FEA).2 The FEA data includes pro-
jections to 1991. This data is a projection of a composite wholesale
cost index for fuels and power and assumes a periodic increase in foreign
oil prices and deregulation of domestic prices. The index also includes
assumptions of price increases for other fuels such as natural gas and
coal, and includes their effect on the overall cost of fuels. Therefore,
while the index may not exactly predict the increases in the cost of fuel
oil alone, it is expected to give a good indication of overall fuel costs.
The last four years are an extrapolation of the data determined by averag-
ing the previous rates of increase. The projection shown in Figure 8-1 is
that beyond 1980 the cost is expected to increase about the same as the
general rate of inflation, 3 to 4 percent.3
Labor
Figure 8-2 shows the trend for unit labor cost. This data was also com-
puted from projected yearly rates of increase with the last four years
being extrapolated. This projection is based on data from the Bureau of
Labor Statistics and the Department of Commerce published by the Federal
Energy Administration.2 Actual wage increases from 1975 to 1995 are ex-
pected to be about 6.5 percent per year, however, productivity gains are
projected to increase at a rate of 2.5 percent per year. This causes the
8-3
-------
rate of increase for unit labor cost to be about 4 percent per year as
shown in Figure 8-2.
Construction
The trend in construction costs is shown in Figure 8-3. The curve is based
on projected average rates of increase in construction costs for electrical
generation plants and transmission plants.4 Long term projections of
construction costs for wastewater treatment plants are not available. Most
of the published projected costs concern residential construction. How-
ever, these residential costs were not used to predict treatment plant
costs. The only available long term (to 1995) projected costs for non-
residential construction are for electrical generation and transmission
plants. These cost projections were compared to the percent increase in
the EPA sewage treatment plant index from 1957 to 1973. It was found that
the historical long term percent increase of the EPA index was about the
same as the projected increase. Based on this favorable comparison the
data for electrical plants is used to predict wastewater treatment plant
construction cost increases shown in Figure 8-3. Figure 8-3 shows a pro-
jected construction cost rate of increase of about 4 percent per year
through 1995.
Consumables
There are no available cost projections for individual consumables used in
wastewater treatment. The trend for consumables is projected from the
wholesale chemical price index (WCI).6 Recent data indicates a slightly
higher rate of increase for the chemical index than the wholesale price
index (WPI) for all commodities. The WCI was 182.3 for October, 1975
while the WPI was 178.9 with the base year being 1967.6'7 This indicates
an absolute difference in the average annual rate of increase since 1967
8-4
-------
of 0.25 percent or a relative difference of 3.4 percent. Data for the
WPI gives the curve shown in Figure 8-4 and if the difference in the
rate of increase of 0.25 percent between these two indexes continues,
the WCI will increase as shown.
REGIONAL COST VARIATIONS
This section presents regional variations from the national averages for
the four cost categories. The variations are presented through map pre-
sentation in four groups: (1) above average by greater than 25 percent,
(2) above average by 5 to 25 percent, (3) average + 5 percent, and
(4) below average by greater than 5 percent.
Electrical Energy
Regional variations of electrical energy costs shown in Figure 8-5 were
prepared for non-residential users by comparing the cost of an average
electric bill in a given state to the average national electric bill.5
The data used to prepare this figure are summarized in Table 8-1.
Labor
The regional variations for labor costs are shown in Figure 8-6. Cost
for common laborers, reinforcement iron workers and carpenters are com-
piled for the EPA construction cost indexes, in manhours per $1000, for
25 large cities and 25 smaller cities. The labor costs for the cities
are compared to the national averages resulting in the percent variations
shown in Tables 8-2 and 8-3. The national averages were calculated by
averaging the labor costs for the same cities. As shown in the tables,
no labor costs exceeded the average by more than 25 percent; the
highest is 18 percent for San Francisco and Bakersfield, California.
8-5
-------
Construction
Regional variations in construction costs are shown in Figure 8-7.
Data for this category were compiled from EPA cost indexes for con-
structing a 50 mgd activated sludge plant followed by chemical
clarification and filtration in 25 large cities and a 5 mgd plant
in smaller cities. These data are summarized in Tables 8-4 and
8-5. Percent variations were computed similar to the method used
for labor costs.
Consumables
No data are available for regional variations in the wholesale cost of
chemicals used in wastewater treatment. Data for regional variations
in the wholesale price index for all commodities are also not available.
Because of the way the Bureau of Labor Statistics obtains information, '
only national indications are possible; therefore, only one index is
computed. Regional variations are available for the consumer price index
and these data indicate all cities are within the "average + percent"
category as shown in Table 8-5. The extreme deviations occurred in
New York (+3.5 percent) and Seattle (-3.9 percent).
8-6
-------
260
220
X
UJ
o
3 180
in
8
140
100
75
80
85
YEAR
90
NATIONAL WHOLESALE COST OF POWER
(Data from Reference 2)
95
FIGURE 8-1
8-7
-------
260
220
180
140
100
76
80
85
YEAR
90
95
NATIONAL UNIT LABOR COST
(Data from Reference 2)
FIGURE 8-2
8-8
-------
260
220
X
8'
180
140
100
80
85
YEAR
90
95
NATIONAL CONSTRUCTION COST
(Adapted from information in Reference 4)
FIGURE 8-3
8-9
-------
260
220
X
Ul
Q
z
o
180
140
100
75
WCI-
WPI
80
85
YEAR
90
95
NATIONAL WHOLESALE CHEMICAL INDEX (WCI) AND
WHOLESALE PRICE INDEX(WPI)
(Adapted from information in References 2 and 7)
FIGURE 8-4
8-10
-------
TJ
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8-11
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8-12
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8-13
-------
TABLE 8-1
ELECTRICAL ENERGY COSTS BY STATES
DATA FOR INDUSTRIAL USERS
(Data From Reference 8)
State
Wash.
Ore.
Cal.
Idaho
Nev.
Mont.
Utah
Ariz.
Wyo.
Colo.
New Mex.
Tex.
N.D.
S.D.
Nebr.
Kansas
Ok! a.
Minn.
Iowa
Missouri
Ark.
La.
Wise.
111.
Miss.
Bill*
(dollars)
1868
2396
4261
2720
3964
3226
3279
4640
2907
3697
4327
3277
4730
4305
3310
4088
3222
4560
4192
4468
4038
3731
4591
4606
4174
Deviation
(percent)
- 57
- 45
- 1
- 37
- 8
- 25
- 24
+ 7
- 33
- 14
0
- 24
+ 10
0
- 23
- 5
- 25
+ 6
- 3
+ 3
- 7
- 14
+ 6
+ 7
- 3
State
Ind.
Ky.
Tenn.
Ala.
Mich.
Ohio
Fla.
Ga.
S.C.
N.C.
Va.
W.Va.
Pa.
N.Y.
Md.
Del.
Wash.
N.J.
Conn.
Mass.
R.I.
Vt.
N.H.
Maine
D.C.
Bill*
(dollars)
4092
3648
3407
4225
5464
4408
4513
4712
3465
3318
4073
3562
5207
10374
5403
5542
5839
5309
5649
5921
5713
4835
4478
3930
Deviation
(percent)
- 5
- 16
- 21
- 2
+ 27
+ 2
+ 5
+ 9
- 20
- 23
- 6
- 18
+ 21
+ 140
+ 25
+ 28
+ 35
+ 23
+ 31
+ 37
+ 32
+ 12
+ 4
- 9
*1974 Data - Average = $4,320
8-14
-------
TABLE 8-2
REGIONAL VARIATIONS IN LABOR COSTS FOR LARGE CITIES
City
Atlanta, Ga.
Baltimore, Md.
Birmingham., Ala.
Boston, Mass
Charlotte, N.C.
Chicago, 111.
Cincinnati, Ohio
Cleveland, Ohio
Dallas, Texas
Denver, Colo.
Detroit, Mich
Houston, Texas
Kansas City, Mo.
Los Angeles, CA
Miami, Fla.
Milwaukee, Wis.
Minneapolis, Minn.
New Orleans, La.
New York, N.Y.
Philadelphia, PA
Pittsburgh, PA
St. Louis, MO
San Francisco, CA
Seattle, Wash.
Trenton, New Jersey
Average
1976
Wage Rate
Manhours/$1000
39.36
37.10
40.19
37.31
50.94
36.14
34.25
34.09,
37.93
35.10
33.14
36.55
34.82
32.52
35.98
34.19
36.51
39.85
33.27 .
35.17
36.72
37.50
30.77
35.57
34.87
36.39
Variation
(percent^
-8.0
-2.0
-9.0
-2.0
-29.0
+1
+6
+7
-7
+4
+10
0
+ 5
+12
+1
+6
0
-9
+9
+3
-1
_2
+18
+2
+4
8-15
-------
TABLE 8-3
REGIONAL VARIATIONS IN LABOR COSTS FOR SMALL CITIES
City
Bakers-field, CA
Blsmark, N. D.
Burlington, VT
Casper, Wyo.
Charlestown, S.C.
Cumberland, MD
Duluth, Minn
Eugene, Oregon
Gainesville, FLA
Green Bay, Wis.
Harrisburg, PA
Las Vegas, Nevada
Mobile, Alabama
Muncie, Indiana
Pocatello, Idaho
Pueblo, Colo
Rapid City, S. D.
Roanoke, Virginia
Saginaw, Michigan
St. Joseph, Missouri
Sioux City, Iowa
Syracuse, N.Y.
Tulsa, Oklahoma
Waco, Texas
Wheeling, West Virginia
Average
1976
Wage Rate
Manhours/$1000
29.49
37.53
36.33
33.07
48.01
35.43
34.19
30.95
35.59
35.66
32.44
29.81
36.80
33.99
31.81
31.74
35.40
39.10
32.35
34.16
34.06
33.21
33.59
38.76
34.48
Variation
(percent!
+18
- 7
- 4
+ 5
-28
- 2
* 2
+12
- 2
- 3
+ 7
+16
- 6
+ 2
+ 9
+ 9
- 2
-11
+ 7
+ 2
+ 2
+ 5
+ 3
-10
+ 1
34.72
8-16
-------
TABLE 8-4
REGIONAL VARIATIONS 50 mgd PLANT COSTS
EPA INDEXES
City
Atlanta, Ga
Baltimore, Md
Birmingham, Ala
Boston, Mass
Charlotte, NC
Chicago, 111
Cincinnati, Ohio
Cleveland, Ohio
Dallas, Texas
Denver, Colo
Detroit, Mich
Houston, Texas
Kansas City, Kan
Los Angeles, Cal
Miami, Fla
Milwaukee, Wise
Minneapolis, Minn
New Orleans, La
New York, NY
Philadelphia, Pa
Pittsburgh, Pa
St. Louis, Mo
San Francisco, Cal
Seattle, Wash
Trenton, NJ
Average
*Base year, 1973
1976
Index*
100
122
99
136
75
140
124
129
95
105
121
104
120
126
106
125
109
113
160
142
126
139
134
124
130
120
Variation
(percent)
- 16.7
+ 1.6
- 17.5
+ 13.3
-- 37.5
+ 16.7
+ 3.3
+ 7.5
- 20.8
- 12.5
t" 0.8
- 13.3
0
+ 5.0
- 11.6
+ 4.2
- 9.1
- 5.8
+ 33.3
+ 18.3
+ 5.0
+ 15.8
+ 11.7
+ 3.3
+ 8.3
8-17
-------
TABLE 8-5
REGIONAL VARIATIONS 5 mgd PLANT COSTS
NEW EPA INDEXES
City
Bakersfield, Ca
Bismarck, ND
Burlington, Vt
Casper, Wyo
Charleston, SC
Cumberland, Md
Duluth, Minn
Eugene, Oregon
Gainesville, Fla
Green Bay, Wise
Harrisburg, Pa
Las Vegas, Nev
Mobile, Ala
Muncie, Indiana
Pocatello, Idaho
Pueblo, Colo
Rapid City, SD
Roanoke, Virginia
Saginaw, Mich
St. Joseph, Missouri
Sioux City, Iowa
Syracuse, NY
Tulsa, Okla
Waco, Texas
Wheeling, West Virginia
Average
* Base year, 1973
1976
Index*
119
100
102
105
77
128
109
122
98
121
129
127
120
113
108
99
95
105
118
113
107
139
98
88
122
110
Variation
(percent)
+ 8.1
- 9.1
- 7.3
- 4.5
- 30.0
+ 16.4
- 0.9
+ 10.9
- 10.9
+ 10.0
+ 19.0
+ 15.4
+ 8.2
+ 1.8
- 1.8
- 10.0
- 13.6
- 4.5
+ 7.3
+ 1.8
- 2.7
+ 26.4
- 10.9
- 20.0
+ 10.9
8-18
-------
TABLE 8-6
REGIONAL VARIATION IN CONSUMER PRICE INDEX
City
Chicago, 111
Detroit, Mich
Los Angeles , Ca
New York, NY
Philadelphia, pa
Boston , Mass
Houston } Texas
Minneapolis, Minn
Pittsburg , pa
Buffalo, NY
Cleveland, Ohio
Dallas , Texas
Milwaukee, Wise
San Diego , Ca
Seattle, Wash
Washington
Atlanta, Georgia
Baltimore, Md
Cincinnati , Ohio
Kansas City, Kan
St. Louis , Mo.
San Francisco, Ca
Average
*Base year, 1967
1976
Index*
159.6
162.9
160.4
169.3
166.9
163.0
165.8
161.9
161.7
163.5
162.4
160.6
159.2
162.5
157.3
163.4
164.7
167.6
163.9
160.2
158.9
161.5
163.6
Variation
(percent)
- 2.4
- 0.4
- 2.0
+ 3.5
+ 2.0
- 0.4
+ 1.3
- 1.0
- 1.2 -
- 0.1
- 0.7
- 1.8
- 2.7
- 0.7
- 3.9
- 0.1
+ 0.7
+ 2.4
+ 0.2
- 2.1
- 2.9
- 1.3
8-19
-------
REFERENCES - CHAPTER 8
1. Barish, Norman N., "Economic Analysis," McGraw-Hill, New York, 1962, pp.
514-16.
2. "National Energy Outlook," Federal Energy Administration, 1976.
3. Allen, Clyde H., "Economics of Energy Supply and Demand: The Pricing of Energy,"
paper presented at Energy Conservation in the Design of Water Quality Control
Facilities Conference, Kansas City, May 24-25, 1976.
4. "The Public Utility Industry," Hearings before Congress, December 1974.
5 Clean Water Fact Sheet, Municipal Division Office of Water Program Operations,
EPA, May 14, 1976.
6. "Chemistry and Industry," Number 2/Saturday 17 January 1976.
7. "Wholesale Price Indexes," Supplement 1975 to data for 1974, Bureau of Labor
Statistics.
8. "Typical Electric Bills," Federal Power Commission, 1974.
8-20
-------
CHAPTER 9
ENERGY EFFECTIVENESS AND COST EFFECTIVENESS
INTRODUCTION
The purpose of this chapter is to discuss the relationships between
energy effectiveness and cost effectiveness through the use of three
examples. Each of the examples compares two alternative 5 and 25 mgd
treatment systems for meeting a specified effluent standard:
ExamP1e ] compares trickling filter and activated sludge systems
to meet secondary effluent standards of BOD = 30 mg/1 and SS = 30
mg/1.
ExamP1e 2 compares independent physical-chemical treatment (IPC)
with activated sludge, followed by chemical clarification and
filtration to meet higher than secondary effluent standards of BOD
= 10 to 20 mg/1, SS = 5 mg/1 and total phosphorus = 1 mg/1.
E.xamP1e 3 compares a total AWT system with land treatment by spray
irrigation to meet effluent standards of BOD = 1 mg/1, SS = 1 mg/1,
P = 0.1 mg/1 and N(total) = 3 mg/1.
Primary energy requirements used in these examples are from the curves
in Chapter 3 and secondary requirements from Table 4-1.
Construction costs are based on the authors' experience and include all
site work, equipment, installation, engineering and administrative
costs, interest during construction and other costs normally required
for a complete and operable facility. The EPA Treatment Plant Index at
the time of these estimates was 257.8. The cost estimates are considered
representative of a typical installation and do not include allowances
9-1
-------
for any unusual local conditions. The estimates are based on generalized
cost data and are for illustrative purposes only.
Operating and maintenance cost estimates are based on the following unit
prices.
Labor
Electricity
Natural Gas
Alum
Activated Carbon
Chlorine
Lime
Polymer (wastewater)
Polymer (sludge conditioning)
$7.00/hr
$0.025/kwh
$1.50/million Btu
$70/ton
$1,000/ton
$220/ton
$37/ton
$0.30/lb
$2.00/1b
Total operating and maintenance costs in the examples include costs for
primary and secondary energy, labor, material, supplies and chemicals.
EXAMPLE 1 - SECONDARY TREATMENT
Flow diagrams for the trickling filter and activated sludge alternates in
this example are shown in Figure 9-1. The following requirements and cost
estimates are summarized from the.energy data in Tables 9-1 and 9-2
and the cost data in Table 9-3.
Total Primary and
Secondary Energy
Thousand kwh/yr
Million Btu/yr
Trickling
Fi1ter
1,117
5,713
Treatment System and Capacity
5 mgd 25 tngd
Activated
Sludge
2,066
25,908
Trickling
Filter
5,207
28,332
Activated
Sludge
9,502
135,570
9-2
-------
Costs
Construction, $1,000
Primary Energy, $l,000/yr
Total 0 & M, $l,000/yr
Total Annual, $l,000/yr
6-1/8% - 20 yr
7% - 20 yr
10% - 20 yr
Treatment System and Capacity
25 mgd
Trickling
Filter
4,935
29
200
635
666
780
Activated
Sludge
6,990
83
351
966
1,011
1.172
Trickling
Filter
16,210
135
606
2,034
2,136
2,510
Activated
SI udqe
18,505
402
1.312
2,942
3,059
3,486
These estimates indicate that activated sludge plants are more costly than
trickling filter facilities. However, most of the cost difference between
these two alternatives is in the sludge treatment processes as shown in
Table 9-3. The thickening, vacuum filtration and incineration processes
used in the activated sludge alternative are more costly to construct and
operate than thickening and anaerobic digestion in the trickling filter
alternative. Of course, anaerobic digestion can be used for sludge treat-
ment in activated sludge plants as well as in trickling filter facilities.
Energy requirements for fuel are almost all for sludge treatment; building
heating and secondary requirements are a small percentage of the,total.
Fuel requirements for incineration remain nearly constant for any location
and climate, but requirements for digester heating vary with sludge and
outside air temperatures. Digester heat requirements in this example are
based on an influent sludge temperature of 60°F in a plant located in the
Southern U.S.
Primary electrical energy use is higher for the activated sludge alterna-
tive because of the aeration requirements. Secondary electrical energy
requirements for chlorine production are the same in both alternatives.
9-3
-------
The cost and energy estimates for these two alternatives demonstrate
that a careful evaluation must be conducted for a specific application
since the differences are not conclusive for all potential plant sites.
EXAMPLE 2 - HIGHER THAN SECONDARY TREATMENT
Flow diagrams for activated sludge treatment, plus chemical clarification
and filtration, and IPC treatment alternatives are shown in Figure 9-2.
These alternatives may not be directly comparable for some applications
because it may be difficult to achieve the effluent quality goal of 10
to 20 mg/1 BOD for a particular wastewater. A combination of biological
and physical-chemical treatment systems is almost always more efficient
than either system alone.
The following energy and cost estimates are summarized from energy data
in Tables 9-4 and 9-5 and cost data in Table 9-6.
Treatment System and Capacity
25 mgd
Primary Energy
Thousand kwh/yr
Million Btu/yr
Secondary Energy
Thousand kwh/yr
Million Btu/yr
Costs
Construction, $1,000
Primary Energy, $l,000/yr
Total 0 & M, $l,000/yr
Total Annual, $l,000/yr
6-1/8% - 20 yr
7% - 20 yr
- 20 yr
«
IPC
1,476
55,438
305
17,309
9,112
120
573
1,377
1,434
1,645
Act. Sludge
+ AWT
1,996
24,238
305
2,040
8,935
86
518
1,305
1,361
1,568
IPC
6,945
292,692
1,525
86,545
27,051
613
2,304
4,687
4,858
5,482
Act. Sludge
+ AWT
8,847
125,592
1,525
10,200
26,114
409
1,931
4,231
4,396
4,998
9-4
-------
The estimated construction costs for the two alternatives are nearly
identical well within the accuracy of the estimates. The total opera-
te and maintenance costs are also close (less than 10 percent difference)
for the two alternatives. The most significant difference is the higher
secondary energy requirements for IPC treatment. This secondary energy
requirements difference is reflected in the higher cost for chemicals.
The IPC system is, therefore, more susceptible to chemical price increases
and energy curtailments resulting in chemical shortages than the activated
sludge system.
EXAMPLE 3 - HIGHER THAN SECONDARY TREATMENT
This example compares two systems that are capable of producing an
extremely high quality effluent (BOD = 1 mg/1. SS = 1 mg/1 P - 0 1
mg/1 and N (total) - 3 mg/1). ln order to achieve this quality effluent,
nitrification and denitrification have been added to the AWT system in
Example 2. This system was compared to the land treatment system shown
in Example 14 of Chapter 6. Costs and energy requirements are based on
solid set sprinklers operating under the conditions listed in Figure 3-
79. The following tabulation summarizes the energy and cost estimates.
Treatment System and Capacity
5 m9d 25 mgd
Primary Energy
Thousand kwh/yr
Million Btu/yr
Secondary Energy
Thousand kwh/yr
Million Btu/yr
Costs
Construction, $1,000
Primary Energy, $1,000/yr
Total 0 & M, $1,000/yr
Total Annual, $l,000/yr
6-1/8% - 20 yr
7% - 20 yr
10% - 20 yr
Land Total
Treatment AWT
Land Total
Treatment AWT
2,701
0
0
0
3,172
24,230
305
24,200
12,433
0
0
0
14,697
125,592
1,525
120,900
9,600
68
210
1,056
1,116
1,337
12,061
116
624
1,687
1,763
2,041
40,000
311
700
4,224
4,475
5,396
35,393
555
2,294
5,412
5,635
6,453
9-5
-------
Land costs are included in the construction costs and crop revenues
(negative costs) are included in the total annual costs .of the land
treatment system. The electrical energy requirements for the total
AWT system are approximately 15 percent greater than those of the
'land treatment system, which requires zero primary fuel input. The
secondary energy fuel requirements for the total AWT system are ex-
tremely high due to the energy requirements for the production of methanol
(36 x 106 Btu/ton). A review of the costs shows that the 0 & M cost
of a land treatment system is 58 percent of the total AWT system. The
impact of the scale on construction costs is reflected in the total
annual cost of the system.
9-6
-------
WASTE
WATER
7 " ' \ TATION I
\ .^r^
CHLORI.
NATION
TREATED
»
EFFLUENT
V
»
VACUUM
FILTER
INCINERATION
I
ASH TO DISPOSAL
ACTIVATED SLUDGE
RECYCLE
INFLUENT
PRELIMINARY
TREATMENT
PRIMARY
SEDIMEN
TATION
SECONDARY
SEDIMEN-
TATION
I
SLUDGE DRYING BED
T
*
LAND DISPOSAL
TRKXLING FILTER
EXAMPLE 1
SECONDARY TREATMENT
CHLORU
NATION
WASTEWATER
SOLIDS
FIGURE 9-1
9-7
-------
INFLUENT
WASTE
WATER
CHEMICAL
CLARIFI-
CATION
SECONDARY
SEDIMEN-
TATION
PRIMARY
SEDIMEN
TATION
CHLORI
NATION
TREATED!
EFFLUENl
ASH TO DISPOSAL
ACTIVATED SLUDGE AND AWT
INFLUENT
WASTE
WATER
GRANULAR
ACTIVATED
CARBON
DSORPTION
PRELIMINARY
TREATMENT
WASTEWATER
SOLIDS
ASH TO DISPOSAL
INDEPENDENT PHYSICAL CHEMICAL
EXAMPLE 2
HIGHER THAN SECONDARY TREATMENT
FIGURE 9-2
9-8
-------
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9-10
-------
TABLE 9-3
COST ESTIMATES
ACTIVATED SLUDGE AND TRICKLING FILTER
SECONDARY TREATMENT
(FLOW DIAGRAM FIGURE 9-1)
5 mgd
Construction. $1.000
Wastewater Treatment
Sludge Treatment
Total
Operation and Maintenance
$l,000/yr
Labor
Material
Electricity
Fuel
Chemicals
Total
Trickling
Filter
4,035
900
4,935
122
32
20
9
17
200
Activated
Sludge
3,582
3,408
6,990
136
51
44
39
81
351
Trickling
Filter
12,829
3,381
16,210
297
90
92
43
84
606
Activated
Sludge
13,155
5,350
18,505
364
140
199
203
406
1,312
9-11
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'»..
-------
TABLE 9-6
COST ESTIMATES
ACTIVATED SLUDGE AND INDEPENDENT PHYSICAL CHEMICAL
HIGHER THAN SECONDARY TREATMENT
(FLOW DIAGRAM FIGURE 9-2)
IPC
Construction, $1,000. 9,112
5 mgd
Activated
Sludge
8,935
25 mgd
IPC
27,051
Acti vated
Sludge
26,114
Operation and Maintenance
$1.000/yr
Labor
Material
Electricity
Fuel
Chemicals
Total
178
53
37
83
222
573
198
64
50
36
170
518
418
161
174
439
1,112
2,304
486
185
221
188
851
1,931
9-14
-------
CHAPTER 10
ENERGY IMPLICATIONS OF SEPARATE AND
COMBINED SEWERS AND INFILTRATION/INFLOW
INTRODUCTION
Energy requirement curves are presented in this chapter for the treat-
ment of storm and combined flows and infiltration/inflow for POTW sizes
from 5 to 200 mgd. Power requirements, based on unit process design
parameters, were determined for the following processes:
1. Swirl concentrator
2. Screens
a. Stationary
b. Horizontal shaft
c. Vertical shaft
3. Air flotation
4. High rate filtration
5. Flow equalization
a. Storage
b. Sedimentation
c. Sludge removal
6. Chiorination
a. High intensity mixing
b. Chlorine gas
c. Chlorine dioxide
d. Hypochlorite
e. Dechlorination
Design criteria were selected in order to show energy requirements for
various plant capacities. These design criteria are variable for specific
local circumstances or flow characteristics, in terms of quantity variations
10-1
-------
(unit hydrograph) and quality variations (seasonal and during-storm).
The unit processes may be used individually or in combination with others.
For example, a screening device may be provided ahead of a dissolved air
flotation unit. The choice of unit process combinations will depend on
local circumstances. Generalized storm water characteristics were
developed by Metcalf and Eddy7 and include the following:
BOD,
mq/1
1 ?* * .
115
30
Suspended
Solids,
mg/1
410
630
Total
Col i form
MPN/100 ml
5 x 106
4 x 105
Total Total
Nitrogen, Phosphorus,
mq/1 as N mg/1 as P.
11
3
4
1
Combined Sewage
Surface Runoff
The energy required to operate a storm water treatment facility is composed
of the process equipment which is active only during the overflow period and
heating and lighting of enclosed spaces. The cost associated with the power
may basically be a demand charge since the power use is so low compared to
the maximum demand; however, many water utilities have rate schedules which
incorporate the demand into other utility facilities locations which tends
to average demand charges across the system. The rates for a specific lo-
cation should be investigated prior to assigning a unit charge.
Energy requirements are presented in terms of kwh/yr and Btu/yr for varying
time of operation. The average energy usage will be a function of a flow
somewhat less than the peak recorded flow. The rated plant capacity must
be equal to the peak storm event. Most storm overflows will not cause treat-
ment plants to operate at full capacity; review of typical storm hydrographs
show that plants will operate at peak flow only for a portion of time. The
flow selected for estimating the energy requirements will be a function of
variation in storm flows and of the unit hydrographs which are a function
of the collection system and each individual storm. For this report, the
flow rate for average energy consumption was assumed to be 45 percent of
the rated capacity of the treatment plant.
10-2
-------
SWIRL CONCENTRATOR
A swirl concentrator requires nd energy except that needed to recover
hydraulic headlosses through the system. These headlosses would depend
on the particular system design. Generally, this process headloss
would be similar to a sedimentation tank headloss of 2 to 6 feet.9
SCREENS
Stationary
A stationary screen requires no energy except that needed to recover
hydraulic headlosses through the system. As with swirl concentrators,
headlosses depend on the particular system design. The stationary
screen headloss will normally be 3 to 8 feet.4'5
Horizontal Shaft Rotary Screen (Microscreen)
The wastewater enters the interior of a slowly rotating drum and discharges
through the screen into a collection chamber. Screen submergence typi-
cally varies from 74 to 83 percent and is sized based on loadings in
gpm/sq ft. The power required to operate the screen includes the screen
rotation drive, washwater supply pump, and instrument air compressor.
Power required for each of these functions is as follows:
Screen
Surface Area
sq ft
315
630
1,260
2,520
5.040
Rotational Washwater Instrumentation
hp Supply Pump, hp Air, hp
5
7.5
15
30
60
5
7.5
15
30
60
1
2
4
8
16
Electrical
Energy Use
kwh/day
195
303
605
1,210
2,419
10-3
-------
Exact design criteria are difficult to establish. Work in the Phila-
delphia area3 showed successful operation for a loading range of 35 to
45 gpm/sq ft. A second study7 shows a wide range of values on reported
facilities, but recommends 5 to 10 gpm/sq ft for low rate and 20 to 50
gpm/sq ft for high rate screens. Based on this information, and assuming
a high rate system, 35 gpm/sq ft is the loading rate shown in Figure 10-1.
Vertical Shaft Rotary Screens
Energy requirements are based on the use of the SWECO centrifuge wastewater
concentrator. Each unit is driven by a 5 hp motor and requires 10 gpm at
80 psi backspray. The horsepower required for the backspray is -about 0.75
hp per screen unit.
Additional energy is required to heat the backspray water from an assumed
60°F to 160°F. Each unit requires 100,000 Btu/hr of operation. Instrument
air compressor requirements are about 0.25 hp. The resulting energy require-
ment is 6 hp per operating screen or 2.7 hp avg/screen/hr of overflow. The
100,000 Btu/hr avg per screen for heating the backwash water results in an
average of 45,000 Btu/hr/screen. Figures 10-2 and 10-3 show energy require-
ments for vertical shaft rotary screens.
A design loading rate of 80 gpm/sq ft of screen surface area is shown in
Figures 10-2 and 10-3. The design was determined based on the manufac-
turer's rating of the unit and expressing that loading in terms of gpm/sq ft.
AIR FLOTATION
The power to operate an air flotation unit varies with the manufacturer.
The two major manufacturers of air flotation equipment use a different
recycle ratio and thereby require different power utilization. Energy
required is approximately 0.10 kwh/sq ft for units with surface areas
larger than 2,000 sq ft.
10-4
-------
Design loading rates for dissolved air flotation units have been reported
from 1,530 to 5,690 gpd/sq ft.1'2'6'8 These reported units were preceded
by screening devices. The design loading rate is dependent on the influent
waste characteristics and the type or size of screening device preceding
the flotation unit. A typical loading rate of 3,500 gpd/sq ft is shown
in Figure 10-4.
HIGH RATE FILTRATION
The direct power requirements for filtration are backwash and surface wash
pumping and instrumentation. Backwash and surface washwater normally
require 5 percent of the average flow rate at 25 ft TDH. For an average
flow of 45 percent of the flow capacity of the facility, the energy require-
ments are about 8 hp-hr/mil gal. Assuming 0.67 hp/fliter for instrumenta-
tion, the total energy requirements are as shown in Figure 10-5.
Gravity filters are assumed for this application and main stream pumping
may or may not be required depending on site conditions. Pumping energy
requirements are shown in Chapter 3 for varying pumping heads.
Design loadings have been reported from 8 to 40 gpm/sq ft.7 A design
loading rate of 15 gpm/sq ft and no main stream pumping is used for the
energy requirements shown in Figure 10-5. This loading rate is applicable
when high rate filtration units are preceded by a screening device.
FLOW EQUALIZATION
Storage
Storage reservoirs may be lined earthen or concrete, open or covered.
Several other concepts have been proposed such as collapsible bladders,
deep underground reservoirs, and short term flooding of open spaces.
The energy requirement shown in Figure 10-6 is for a spray system to
wash the reservoir walls and floor to remove deposited solids. The spray
10-5
-------
water quantity is 3 gpm for 10 nrin/sq ft of reservoir wall and floor
area and the pressure is 60 psi.
The plant capacities shown in Figure 10-6 were determined by assuming a
12 hr detention time. This criterion will vary considerably depending
on the treatment method and/or effluent standard.
Sedimentation
Energy required for sedimentation basins equipped with mechanical sludge
removal mechanisms is shown in Figure 10-7. Sludge pumping is not included
in this figure. Sedimentation energy requirements are presented in
Chapter 3. Sedimentation basin sizing is based on 1,000 gpd/sq ft
surface loading rate at 45 percent of design flow capacity or 2,222 gpd/
sq ft surface loading rate at design flow.
Sludge Removal
Energy requirements for sludge pumping are based on the use of positive
displacement pumps (efficiency = 40 percent) and intermittent pumping
(10 min each hr). A 25 ft TDH was used to develop the energy require-
ments shown in Figure 10-8.
The sizing of the sludge pumps is based on removal of 2,200 Ib/mil gal
at 45 percent of design flow capacity (assume sludge can be stored in
sedimentation tank if quantity of solids temporarily exceed pumping
capacity).
CHLORINATION
Chlorine dosages are highly variable depending on the storm water quality
and type of unit process applied. A dosage of 10 mg/1 is used for the
energy requirements presented in this chapter.
10-6
-------
High Intensity Mixing
Energy requirements for high intensity mixing are based on a G value of
300 sec'1 and water temperature of 15°C. Energy requirements are shown
in Figure 10-9. Plant capacities shown in this figure are based on a 1
min detention time.
Chlorine Gas
Power requirements for chlorine feed equipment are small but increase sub-
stantially where evaporators are used to convert liquid chlorine to the
gaseous form. Standard size chlorinators are rated at 400, 2,000 and
8,000 Ib/day. If a 2,000 Ib/day or 8,000 Ib/day unit is required, then
an evaporator is normally used. Therefore, the total energy requirement
is 135 Btu of chlorine evaporated and is applicable when the dosage exceeds
400 Ib/day. Energy requirements shown in Figure 10-10 are applicable for
dosages greater than 4 tons/yr for a 20 day occurrence, 8 tons/yr for a
40 day occurrence, etc. The top abscissa shows plant capacity for 20 days
operation/yr. For more frequent operation the scale would shift to the
right but the plotted line would not change.
Chlorine Dioxide
Power for chlorine dioxide systems consists of chlorinator, sodium chlorite
mixer and diaphragm feed pump requirements. The chlorinator feed require-
ment is 1.68 times the desired chlorine dioxide feed rate. Energy require-
ments shown in Figure 10-11 are based on a line pressure of 10 psi and
pumping efficiency of 40 percent. Plant capacities shown in Figure 10-11
are based on a feed concentration of 1.2 mg/1.
Hypochlorite
Energy requirements for hypochlorite generators vary between equipment
manufacturers. A typical energy requirement for on-site generation of
10-7
-------
sodium hypochlorite is 2.5 kwh/lb of chlorine equivalent. Energy require-
ments shown in Figure 10-12 are for 20 days of overflow.
Dechlorination
Assuming dechlorination by addition of sulfur dioxide.the energy requirements
per pound will be identical to that needed per pound of chlorine additions.
Evaporator energy is the most significant power requirement. The latent heat
of vaporization for sulfur dioxide is 150 Btu/lb at 70°F. The dosages
for sulfur dioxide will be less than the chlorine dosage. This difference
depends on the demand of the water treated. The amount of sulfur dioxide
dosage is nearly equal to the chlorine residual (0.9:1.0). Therefore, the
energy required is determined by multiplying the chlorine feed energy require-
ment (Figure 10-10) by the ratio of sulfur dioxide dosage to chlorine dosage.
10-8
-------
PLANT CAPACITY, mgd
( Loading = 35 gpm/sq ft )
or
LU
oc
o
ae
IU
z
LU
g
OS
u
LU
1,000,000
(
1
5
- 100,000
» ' o
: 8
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6
l 5
i
: 4
>
3
2
10,000
1
7
6
5
4
3
2
1,000
5
25
NUMBER OF DAYS
OF OP
X
80' -^ ^
60-^-=^
^^~
40 """
20 -^^
ERAT
X
^/"
j^S
X
ION
Ix
X
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X
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X x
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s
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j-
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x x^
x x/
x"'/
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Z 34 56789 2 34 56789 2
10 100 1,000
00
-" "^
x^
/
3
/
.r
X
4
!00
X
/
-y
/
5 6 789
10,000
SCREEN SURFACE AREA, sq ft
HORIZONTAL SHAFT ROTARY SCREEN
Water Quality: Influent Effluent
(mg/1) (mg/1)
Suspended Solids 410 50
Operating Parameters:
Loadings 35gpm/sq ft
Type of Energy Required: Electrical
FIGURE 10-1
10-9
-------
1,000,000
* 100,
o
UI
tt
o
UJ
C£
s
ce:
ui
z
ui
Of.
t-
U
UI
_J
UI
o
PLANT CAPACITY, mgd
( Loading = 80 gpm/sq ft )
25 50 100
200
9
8
7
6
5
4
3
2
0
9
8
7
6
5
3
2
00
1
N
0
0
UMBE
FOP
80-6
40
t
2
RO
ERA
/
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FC
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f
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7
X
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^
r
/
' /
/
/
£
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y
//
Z_. ^ _,
t---/!
/
/
/
/
/
/
/
/
/
/
/
56789 2 34 56789 Z a 4 ftb/aa
100 1,000 10,000
SCREEN AREA, sq ft
VERTICAL SHAFT ROTARY SCREEN
Water Quality: Influent
(mg/l)
Suspended Solids 410
Operating Parameter:
Loadings 80gpm/sq ft
Type of Energy Required: Electrical
Effluent
(mg/l)
75
FIGURE 10-2
10-10
-------
PLANT CAPACITY, mgd
Loading =t 80 gpm/sq ft )
O
LU
10,000
9
8
7
6
i
4
1,000
9
1
6
1
t
* 1
2
100
i
7
6
5
4
3
2
10
"- n
6
i
80'
y
0'
40
NU
OF
/
x
20
5
i4-
MB
Of
-
/
x
fcROF
ERA'T
\ \A
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._
DAYS >
ION yX
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x X
x
25
T4
X
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i
i
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yl
5(
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^
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x
x
00 20
li i 1
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10 100 1,000
0
^
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3
X
X
4
i ' i
X
x
X
5
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10,001
SCREEN AREA, sq ft
VERTICAL SHAFT, ROTARY SCREEN
(Heating Backwash Water)
Water Quality:
Suspended Solids:
Influent
(mg/l)
410
Effluent
(mg/l)
75
Operating Parameters:
Loadings 80gpm/sqft
Backwash = lOgpm (3 SOpsi, 160* F
Type of Energy Required: Natural Gas
FIGURE 10-3
10-11
-------
PLANT CAPACITY, mgd
(Loadings 3500 gpd/sq ft )
Q
LLJ
O
Ul
on
s
OS
1U
z
Ul
as
u
ui
_J
U)
000,000 .
8
7
6
5
4
3
2
1,000,000
9
8
7
6
5
4
3
Z
100,000
f
7
6
*
4
t
10,000
NU
OF
WBER
OPE
80*^
60^
40
20
2
OF
RAT
j£-
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"tf
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50
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//
'//
100
/
/
/
/
~~?
y.
/
/
200
s\
^
/
89 2 345 6789 2 3 4 5 b {»*»
100
SURFACE AREA, sq ft
AIR FLOTATION
Water Quality: Influent Effluent
(mg/l) (mg/l)
Suspended Solids 150 30
Design Assumptions:
Preceeded by screening device.
Polymers are used.
Operating Parameters:
Loading » 3500gpd/sq ft
Pressurized Flow = 15%
Type of Energy Required: Electrical
FIGURE 10-4
10-12
-------
1,000,000
1,000
100
PLANT CAPACITY. mgd
(Loading as 15 gpm/sq ft)
25 50 100 200
2 34567 89
1,000
2 3 4 5 6 789
10,000
2 3456 789
100,000
FILTER SURFACE AREA, sq ft
HIGH RATE FILTRATION
Water Quality: |nf|uent
Suspended Solids 50
Design Assumptions:
Mixed Media
Preceeded by Microscreen
Operating Parameters:
Loading s ISgpm/sq ft
Backwash rate a 20gpm/sq ft
Type of Energy Required: Electrical
Effluent
(mg/l)
10
FIGURE 10-5
10-13
-------
PLANT CAPACITY, mgd
(12 hr detention)
100,000
9
8
7
6
5
4
3
2
< 10,000
»c 9
S S
ELECTRICAL ENERGY REQUIRED, k
- g
y N oi -^ WO-4OKD0 ro 01 * w m->i
5
"'
x-
/
^
^
^
x^^
X'
25
^^
^
s'
2 3 4 56789
50
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^
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x^
1
^X
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x'"'
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^^
200
NU
OF
__.^±-_
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^^
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WBER
OPE
80-
6U
40
20
OF
RAT
DA
101
kYS
4
2 3 4 56789^ 2 S . O , , ^
RESERVOIR VOLUME, mil gal
STORAGE RESERVOIRS
Operating Parameters:
Detention time =12 hours
Spray Water = 3gpm/10min /sq ft of reservoir wall
Water Pressure: 60psi
Type of Energy Required: Electrical
FIGURE 10-6
10-14
-------
PLANTCAPACITY/mgd
[ Loading = 1000 gpd/sq ft
100,000
9
8
7
6
5
4
3
Z
-^,
1 10,000
9
a* §
jj 7
£ 6
S 4
I 3
7
/
xx
1,000 * * .* 567!!,9000 2 3 4 567l
SURFACE AREA, sq ft
riff
Nl
OF
S
//
* \s
+ -^~
/
y
w=\
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KOOO 2
MBEI
'OPF
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60
,40
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3
?OF
RA1
!0
4
DAYS
ION
5 6 7i?o?o,ooo
SEDIMENTATION BASINS
Water Quality: Influent Effluent
(mg/l)
Suspended Solids 410 145
Operating Parameter:
Hydraulic loading = l,000gpd/sq ft
Type of Energy Required: Electrical
FIGURE 10-7
10-15
-------
PLANT CAPACITY, mgd
(See operating parameters below)
100,000
9
8
7
6
5
4
3
2
J 10,000
- n
ELECTRICAL ENERGY REQUIRED
2 *, M * om^oxo* N « * «m-i
in
_^
2
3
5
/
/
/
/
25
_^/
5(
)
^
100 20
/
/
f
0
-4
456789 2 3456 789 2 3 ^ o e r o »
TOO ''00° '
AVERAGE SLUDGE FLOW, gpm
WASTE SLUDGE PUMPING
Design Assumptions:
Pomps are run 10 min, each hour.
Sludge concentration is 5%.
Pumping efficiency is 40%.
Operating Parameters:
Sludge removal = 65% of influent suspended solids at
average flow
Average flow - 45% of design flow
Type of Energy Required: Electrical
FIGURE 10-0
10-16
-------
100
PLANT CAPACITY, mgd
( Detention time = Itnin)
567i80
1,000,0(K
4
.ECTRICAL ENERGY REQUIRED, kwh/yr
o S
g g
C3 55
^KBW ro MAC* oi^oxo M
ui e
5
4
3
2
1,000
a
5
/ /
_^ >
,/
H
^
>r
X >^
/
'
/
f"
X
^
7^
/
'/i
/
50
' /
/
/
100 2
00
NUMBER 0
0
/,
-t / f
/ ' S
' S s
y /
/
F OPERA
sn
b
^
>'
'40
?n
F DAY
TION
I
1
ooo
2 34567
RAPID MIX VOLUME, eu ft
RAPID MIXING
Operating Parameters:
G= 300sec-l
Temperature =s 15*C
Detention Time = 1 min
Type af Energy Required: Electrical
FIGURE 10-9
10-17
-------
PLANT CAPACITY, mgd
(Dosage =* 10mg/l for 20 day per year operation)
5 25 50 100 200
100,000
9
8
7
6
5
4
3
2
"^10,000
J< 9
ELECTRICAL ENERGY REQUIRED,
"o
o
§ N 01 * WOTSOXO0 N 01 * 01 0>-J
-------
100,000
100
10
PLANT CAPACITY, mgd
( Dosage s. ] 2 mg/!/20 day per year operation)
25 50 100 200
2 3 456789
10,000
CHLORINE DIOXIDE FEED, Ib/hr
CHLORINE DIOXIDE GENERATION & FEED
Design Assumptions:
Operation * 20 days per year
Average flow = 45% of design flow
Operating Parameter:
Dosage = 1,2mg/l
Type of Energy Required: Electrical
FIGURE 10-11
10-19
-------
10,000,000
-* 1,000,000
a
LU
oe.
O
QJ
ui
z
LU
u
100,000
10,000
(Dosage
5
PLANT CAPACITY, mgd
i 10 mg/l for 20 day per year operation)
25 50 100
200
CHLORINE USAGE, tons/yr
HYPOCHLORITE GENERATION
Design Assumptions:
Operation « 20 days/year
Average flow = 45% of design flow
Operating Parameter:
Dosage = 10mg/l
Type of Energy Required: Electrical
FIGURE 10-12
10-20
-------
REFERENCES - CHAPTER 10
' £&&s£y£z,
'
3- .
Monltorlng, U.S. EPA, EPA-R2-°£l24
4-
-
, ?973?6 °f ReSeai"Ch and
''
EPA-670/2-75-010, May1975
.S. EPA,
8-
No-
"«1nhold Com-
10-21
»U.8. OOVERNMENI PRINTING OFFICE! 197B - 777-066/U27 REGION NO. 8
-------
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i §
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o o
o
30
co O
at ai
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