PROCEDURES FOR EVALUATING
PERFORMANCE OF WASTEWATER TREATMENT PLANTS
A Manual
Prepared for
Environmental Protection Agency
Office of Water Programs
Washington, D.C.
Under Contract No. 68-01-0107
by
URS RESEARCH COMPANY
Environmental Systems Division •••Qj
San Mateo, California 94402
-------
ABSTRACT
This manual establishes a procedure for the
evaluation of the performance of wastewater
treatment plants. Jt furnishes the informa-
tion necessary to identify and classify vari-
ous types of treatment plants. This manual
details the processes commonly utilized in
wastewater treatment. The common problems
affecting plant operation are identified and
described. The description first states the
problem and then identifies the indicators
of the problem, which are listed in order of
their relative importance. The type of lab-
oratory tests which should be performed are
listed, along with other evaluation tech-
niques. Finally, operational, maintenance,
or other corrective measures are listed in
order of their effectiveness.
References are given for an in depth review
of unit and process operation and for addi-
tional information (where applicable). A
glossary is also included.
111
-------
CONTENTS
Section Page
INTRODUCTION 1
I PLANT EVALUATION PROCEDURES 3
Preparation for Site Visit 5
On-Site Inspection 7
Procedures for Problem Evaluation 9
Total Plant Evaluation 10
II WASTEWATER TREATMENT SYSTEMS OPERATIONAL DATA 17
Pretreatment and Primary Treatment Data 19
Secondary Treatment Data 21
Secondary Treatment Data - Activated Sludge Process 23
Advanced Waste Treatment Data 25
Solids Treatment Data 27
Common Solids Treatment Data 29
III SAMPLING AND TESTING
Introduction 31
General 31
The Sampling Program 32
IV COMMON OPERATING PROBLEMS AND SUGGESTED SOLUTIONS
Introduction 41
Pretreatment 49
Primary Treatment 59
Secondary Treatment 64
Advanced Treatment 82
Disinfection 89
Metering 109
Solids Handling 111
iv
-------
Appendix Page
A CLASSIFICATION OF WASTEWATER TREATMENT PLANTS A-l
Classification by Function A-l
Operator Classification A-2
Location of Temperature Zones in the United States A-3
Common Processes and Operational Units A-4
B PERSONNEL REQUIREMENTS B-l
General Skills B-l
Manpower and Work Scheduling B-2
C PRIMARY TREATMENT MODE (Background Information) C-l
General C-l
Pretreatment C-3
Chemical Precipitation C-10
Chlorination C-10
D SECONDARY TREATMENT D-l
General Background of a Biological Reactor D-3
Trickling Filters D-4
Activated Sludge D-6
Stabilization Ponds and Lagoons D-8
Intermittent Sand Filters D-9
Secondary Clarification D-10
Package Aeration Plants D-ll
E ADVANCED WASTEWATER TREATMENT E-l
General Background E-l
Chemical/Physical Treatment E-2
Carbon Adsorption E-3
Ammonia Stripping E-4
Electrodialysis E-5
Reverse Osmosis E-6
-------
Appendix Page
F SOLIDS TREATMENT AND DISPOSAL F-l
General Background F-l
Treatment of Sludge F-2
Sludge Thickening F-3
Sludge Conditioning F-4
Sludge Dewatering F-5
Disposal of Sludge F-6
G CONTROL AND METERING SYSTEMS G-l
Control Systems G-l
Flow Measurement G-2
H MAINTENANCE DATA SYSTEM H-l
J REFERENCES J-l
K GLOSSARY .. K-l
VI
-------
INTRODUCTION
-------
INTRODUCTION
-------
INTRODUCTION
The purpose of this manual is to provide technical guidance for persons
conducting evaluations of wastewater treatment plants and serve as a model
which can be used by state regulatory agencies.
It furnishes the information needed to facilitate identification and
classification of various types of treatment plants. It also details
the processes commonly utilized in wastewater treatment. The common prob-
lems affecting plant operation are identified and described. Several
aspects of each problem are covered: exactly what is the problem; how it
is detected, what are the possible causes, and what solutions are feasible.
It is assumed that the manual user has a general familiarity with both
typical wastewater treatment plant design and operation, as well as a tech-
nical background in sanitary engineering. In addition, the user should
complete a training program which includes the evaluation of a series
of wastewater treatment plants using this manual and other evaluation methods.
As wastewater treatment technology is changing rapidly, this manual
will be reviewed and updated routinely in order to maintain its effective-
ness as a plant evaluation tool.
MANUAL FORMAT
In order for the manual to be an effective tool in the evaluation of
wastewater treatment plants, familiarization with its structure as well
as its advantages and limitations is necessary.
Like any other tool which is being used for a particular purpose, the
manual can be utilized best by familiarization with.:
• TABLE OF CONTENTS - so material can be quickly and
easily located.
• GLOSSARY - to understand the manual terminology.
• 'PLANT OPERATIONAL DATA - to become familiar with
operational parameters, loading rates., and support
systems used with each unit operation.
1
-------
• PLANT CLASSIFICATIONS - to give background information
on the schemes, their processes, and their relation to
a treatment system.
• PLANT EVALUATION PROCEDURES - to become familiar with the
steps required in performing a plant evaluation.
• DATA FOR EVALUATION - an in-depth review of the data
required in conducting a plant evaluation.
This manual contains four principal sections and several supplemental
appendixes:
SECTION I Procedures for Plant Evaluation. This section of
the manual contains a step-by-step procedure for
organizing information before the plant is visited
and for performing the on-site evaluation.
SECTION II Wastewater Treatment Systems Operational Data. This
section of the manual contains data on the common
operating parameters, loading rates, waste products
accumulated from process operation, and the support
systems which are used in the various unit operations
and processes.
SECTION III Sampling and Testing. This section of the manual
contains information on the type of sampling to be
done, location of sampling points, and analyses to be
performed for the particular treatment system.
SECTION IV Common Operating Problems and Suggested Solutions.
This section of the manual is to properly identify
problems which frequently occur in wastewater treat-
ment plants and delineate which corrective measures
should be implemented.
APPENDIX A These appendixes supply the background information
through on the various treatment systems; how they are
APPENDIX G classified, personnel requirements, maintenance
data programs, and information on the various unit
operations.
-------
PROCEDURES
-------
I
PLANT EVALUATION
PROCEDURES
-------
Section I
PLANT EVALUATION PROCEDURES
The evaluation of a wastewater treatment plant consists of an
in-depth analysis of the following basic elements:
• Plant performance
• Operational problems
• Operating personnel
• Sampling and testing program
• Laboratory facilities
• Maintenance data program.
Information and data for each element are gathered and analyzed in
four interrelated phases, namely
1. Preparation for site visit
2. On-site inspection
3. Problem identification
4. Total plant evaluation.
The estimated evaluation time will depend on the size and complexity
of the plant, the amount of preparation on the part of the investigator(s),
and the willingness of the plant personnel to cooperate with the
investigator(s).
For planning purposes the following table gives values which can be
used for the initial evaluation. The estimate of the times required to
perform a treatment plant evaluation will vary with the complexity of the
treatment facility and other factors; this variation could be as great
as 50 percent.
-------
TREATMENT PLANT EVALUATION PERIOD
(days)
Preliminary Preparation
On-Site Investigation
• Visual Inspection
• Record Analysis
• Problem Evaluation
and Solution
Written Report
1
1/4
1/4
1
1
1/2
Plant Size (MGD)
10
1 :
1/2
2* J
0 to 3
1
100
Lj to 2^
1 to l£
l\ to 4
0 to 4
1
Total Days (maximum)
13
-------
PREPARATION FOR SITE VISIT
Preparation for the on-site inspection should include compilation
and review of information which provides a description of the plant's
physical setting, plant design details, plant operating personnel, and any
available performance records, previous inspection reports, compliance
orders, etc. Reference material relevant to the type of plant being evalu-
ated should also be reviewed (see Section II and the Appendixes).
The following are specific steps suggested for use in preparation for
the on-site visit:
1. Compile and Review Information on Plant's Physical Setting
Information describing the physical location of the plant will be
required in the evaluation. The information should include the following:
(a) Classification of Treatment System
• Type of plant (see Appendix A)
• Contributory population (domestic, industrial, etc.)
• Wastewater system (sanitary, combined, etc.)
• Geographic-climatic effects (see Appendix A) to
determine if extreme geographic-climatic areas could
have an effect on plant performance. This should
include both extremes of temperature and precipitation
• Determine, if possible, the characteristics of the
plant's influent and effluent. This should include
both values of the parameters measured by the plant
(BODg, pH, 001} temperature, etc.), and flow quantity and
variations with time.
(b) Identification of Discharge Requirements
For a particular plant location, this might consist of
allowable COD, pH, BOD,-, etc. , or any special controlling
conditions such as a minimum DO and chlorine residuals. If
the official data are not readily available from the plant,
then try contacting local and/or state health departments
and state, regional, and municipal pollutional control
agencies. These agencies may be able to supply the needed
information. These data should then be compared to the
matrix, Table A-2 of Appendix A, which contains expected
effluent quality criteria for various treatment systems.
-------
2. Compile and Review Information Describing the Plant and Staff
This should be accomplished in advance of the plant visit, recognizing
that most state agencies will have some sort of records and previous
evaluations which can be used as a comparison between the past, existing,
and optimum operation of the plant. The information required to make this
comparison includes:
• Size of plant (design, average daily flows, peak flows)
• Type of unit operations
• Historical operating data
• Size of staff, their qualifications, and distri-
butions of time spent between unit operations
• Review all relevant plant documents such as design
drawings, operating manuals for various pieces of major
equipment, and summary (or monthly) operating reports.
This information should be compared with sections of the manual or other
sources which give information on the following:
• Wastewater treatment systems operational data (use
design specifications, where available, or see Section II
of this manual)
• Personnel requirements (see Appendix B)
• Classification of wastewater treatment plants
(see Appendix A).
3. Prepare a Pre-Visit Evaluation Data Sheet
Data will be needed prior to the evaluation to insure adequate data-
gathering at the time of the on-site visit. The pre-visit evaluation guide
should include a summary of all background information.
-------
ON-SITE INSPECTION*
The inspection of the plant should be accomplished in several phases
with each phase being progressively more detailed. The visit(s) would
typically consist of two phases:
Phase One—a general orientation and overview of the plant and
its operation, including:
• Meet initially with plant engineer or chief operator. Have
him describe the plant and its principal operating charac-
teristics, on a schematic basis (this and the following
steps are to help orient you to the plant, but also to
give you an indication of how well the staff understands
the system).
• Interview plant staff members, starting with plant super-
intendent and other supervisory personnel and working
progressively through the appropriate operating personnel.
• Determine routine plant performance and compare this with
design performance and norms section of the manual (see
matrix, Table A-2, Appendix A).
Phase Two—problem identification with an evaluation as to effect
on overall plant performance. This phase also includes the pro
cedure for laboratory evaluation. .^ tf&U&UM X*^
Problem identification begins wifrfa k tour of the facility./ Have the
plant engineer or operator give you a complete tour of the facilities.
Watch for and inquire about:
• Excessive particles and/or floe flowing over overflow weirs
• Excessive grease and scum buildup
• Any unusual equipment such as special pumps, chemical
feeders, temporary construction on structures or other
jury-rigged systems which are being used to correct
problems (or possibly causing them)
• Evidence of flow in by-pass channel to parallel units
because problems have come up in normal operating units
*
Always contact the plant manager in advance to set up an appointment;
avoid ill-will from arriving unannounced.
-------
DDE
• Excessive odors
• Abnormal color of wastewater in various process stages.
If any special plant modifications were made, determine:
• Purpose
• Physical makeup
• Effect on the other treatment processes by comparing
old operational data with data after modification.
REVIEW RECORDS
In general, all records should be analyzed and compared with the
information in the manual and/or other sources for consistency,
method of calculation and to verify that recorded values are within
the range recommended by this manual or other sources.
The following records should be reviewed:
FLOW Hydraulic' data are reviewed for:
• Consistency with the design flow and with present
population served
• Over- and under-loading of the various treatment units.
• Meter calibration
UNIT OPERATIONAL DATA (BOD, COD, Suspended Solids, etc.) are
reviewed for:
• Consistency with design specification and values indicated
in the manual or other sources
• Extreme values for the daily flows.
-^ POWER CONSUMPTION records should be reviewed for values above or
below normal. These records would tend to indicate the following:
• Operating heads lower than the pump's rating
• Specific gravity or viscosity of liquids being pumped
is too high.
POWER CONSUMPTION AND FLOW RECORDS. Analyses of the FLOW data in
combination with POWER might indicate the following:
• Output of each pump separately and pumps collectively
• Unusual operating conditions which are in effect or have occurred
• Changes in efficiency of pumps by comparison of gallons pumped/
kilowatt hour over an extended period of time.
-------
*
MAINTENANCE DATA . The maintenance program is usually a good indi-
cator of operational quality; this can be indicated by checking:
• Manufacturer's maintenance schedule for components
• Type of routine being used for maintenance scheduling (as
compared with Appendix H)
• Personnel qualifications for the type of maintenance work
being performed.
PROCEDURES FOR PROBLEM EVALUATION
In general, the problems detailed in the manual are those most
commonly encountered. However, these procedures can be used for any type
of problem evaluation. The f j.rst step in problem evaluation is to deter-
mine if the plant is meeting design performance standards by comparing
its effluent quality and overall removal efficiencies with those specified
by the design (if design specifications are not available, compare the
plant's performance against the guidelines given, see Appendix A). If the
plant does not routinely meet performance specifications, it will be neces-
sary to determine whether the deficiency is due to problems wtiich fall
into two categories:
PROBLEM DEFINED—If the treatment plant operator has defined
the problem:
a. Verify general area of problems, such as related to
process, maintenance or design, sampling, etc.
b. For common process problems, refer to that section of
the manual dealing with the problem (see Section IV).
c. Develop sampling and testing program to provide
additional data, if needed (see Section III).
PROBLEM UNSPECIFIED—If effluent discharge does not meet required
standards and no definite problem area has been established:
a. Review flow and process records again in greater detail.
b. Recheck sampling and testing procedures required (see
Section III).
c. Compare sampling and testing program against recom-
mended programs in the manual.
d. Recommend a modified testing and sampling program to
furnish additional data for evaluation (see Section III).
* Refer to 0 & M manual requirements.
-------
e. Compare the data with the problem indicators detailed
in the manual (see Section IV) to see if there is a
solution offered.
f. For those problems not specifically covered in the manual,
and if the evaluator's experience does not suffice,
should be recommended that a consultant be hired.
MAINTENANCE PROBLEM—Refer to sample maintenance program (see
Appendix H) and compare with actual plant program; recommend new
program where needed.
TOTAL PLANT EVALUATION
This should include the following:
1. TOTAL EVALUATION OF PLANT—utilizing the Evaluation Guide
materials at the end of this section
(a) Modification of initial evaluation, if appropriate
(b) Differences in existing plant performance and operational
data with design and/or manual operational or performance
data
(c) Personnel needed for adequate operation
(d) Type of sampling program required to give needed data
(e) Maintenance system needed
(f) Laboratory equipment needed
(g) Problems encountered
• Those corrected by visit
• Those that need outside help to correct
• Proposed solutions.
FINAL REPORT—should contain the following elements:
(a) Summary of on-site visit
(b) A list of problems encountered
(c) Solutions recommended
(d) Proposed action.
* See EPA Staffing Guides.
10
-------
Pre-Visit Evaluation Guide
Plant Identification (Name, Owner, etc.)
Plant Location,
Operator in Charge.
Date of Evaluation.
Evaluation by
Date of Plant Construction
Name of Design Firm
Regulatory Agency of Concern
Stage Operating Permit?
Background Informatic
1. Type of Plal
Schematic oj
Contributor]
Domestl
•obtain prior to visit
2.
3.
Low Route to Unit
jpulation
Industrial (P
Other
4. Type of Wast]
Combii
Saniti
iwa'
Indus
5. Geographic
Clin
ftic Effects
,o
Ranges ( F)
Rainfall Extremes (in.)
to
to
11
-------
6. Plant Wastewater Characteristics
Nitro-
gen
Sus-
pended
Solids
(mg/£)
COD
Flow
(MGD)
Dis-
solved
Oxygen
a.
b.
Plant influent
Plant effluent
Overall perform-
ance (%)
Design and/or
manual recommended
performance
values (%)
Existing
receiving water
quality
Required
receiving water
quality
7. Possible Problems
a. Identified from/g^M^ITting reports
b.Identified from/previous inspection reports
c. Complaints
12
-------
On-Site Evaluation Guide
1. Flow
Design (actual).
Daily Average
Peak
Note any variation or erratic flow patterns.
2. Process Units Employed and All Pertinent Information
Unit
Process
Operational Parameters
Existing
Plant
Values
Design and/or
Recommended
Manual Values
Lsting
>lant
Values
Loading Rates
Design and/or
Recommended
Manual Values
3. Historical Operational Data
Organize data to see if following occurred:
Equipment failure - when, what type failure, how long out
of service
Extreme weather conditions
Exdessive loadings on plant:
Flow — when, how long, results of
Organic - when, how long, results of
13
-------
Changes in process operation, such as:
Increasing air flow to activated sludge units
Decreases in detention times
What caused changes? Are changes still in effect? Why?
4. Plant Personnel
Size of Staff for Daily
Average Flow Handled
Qualifications
Types of Shifts
(hours)
Existing
Plant
Recommended Manual
and/or
Other Sources
Existing
Personnel
Recommended
Manual and/or
Other Sources
Exist-
ing
Recom-
mended
Manual
5. Laboratory Evaluati
Type of 1
Treatment
Type
Pests Perfo
; System Ev
Frequency
rmed/for
aluajbed
Location
Testing Procedures
and Equipment Used
Type of Tests Performed
for Treatment System
as per Manual
14
-------
Guide for Overall Evaluation
Yes
No
I. OPERATING PROBLEMS
Are there problems affecting the
performance of this plant?
Can they be solved without major construction?
Are the skills to solve the problem available
among the staff?
Was a solution suggested by the evalua^
Is it a permanent solution?
II. THE SAMPLING AND BESTING PROGRAM
• Are the sa noting locations suitab
Are testin j procedures
Is testing
process co
equency adequ
ol?
III. LABORATORY FACILI
Is the labofra\pry
apparently fun\tio
Is there enough
all the nefessarj
Is the eq
irgdfiized and
is intended?
knt to perform
3tS?
eing properly used?
IV.
PERSONNEL - Planf Operators (including lab personnel)
Is the st^t^eKiequate in size?
• Are theyfqualified? State certified?
• Is thera an operator training program?
• Are the/shifts adequate and balanced?
15
-------
Evaluation Guide - page 2
V. OVERALL PLANT PERFORMANCE
Is it operating to its design
specifications?
Is it meeting discharge requirements
for its location?
Even if adequate, can plant performs
be improved by simple and/or inexper
changes?
Yes
No
Evaluator: If any of'
taken:
1. Submit a
• Sumnu
• A lis
• Solu^
• Prop^
2. Discuss
plant s1
answers are
ollowing steps should be
Ivisit
bins encountered
lions! rqqMmended
ctlon.
^commendations with treatment
In cooptJtaf ion with the plant operator (and local
officials, if necessary), decide on a course of
action fo solve the problem(s).
After af suitable period of time, revisit the
plant fo make a re-evaluation.
16
-------
OPERATIONAL DATA
-------
II
WASTEWATER
TREATMENT SYSTEMS
OPERATIONAL DATA
-------
Section II
WASTEWATER TREATMENT SYSTEMS OPERATIONAL DATA
This section of the manual contains data on the common operating
parameters, loading rates, waste products accumulated from process opera-
tion, and the support systems which are used in the various unit operations
and processes.
Once the plant has been classified and the type of unit operations
and processes have been determined, the information in this section will
serve as a guide to evaluation of the overall plant operation. If operating
and performance data are largely different, investigation of plant processes
should be made to determine if the problem is with equipment or process
failure. These should be noted, and if remedial solutions can be deter-
mined by use of this manual (Problem-Solution Section IV, this manual),
they should be suggested to the plant operator. Where problems are beyond
the scope of this manual, or experience of the evaluator, it should be
suggested that the operator take the necessary steps to get proper outside
help.
In the total evaluation of the plant, a list of problems encountered
should be made and the steps that are being taken or were suggested to cor-
rect them. A return visit should be made after the operator has had suf-
ficient time to correct the problems and a new evaluation made.
17/18
-------
OPERATIONAL DATA ON PRETREATMENT AND
PRIMARY TREATMENT OF WASTEWATER
-------
Table II-l
PRETREATMENT AND PRIMARY TREATMENT DATA
Unit Operations
or Process
Racks
o coarse
o medium
o fine
o mechanically cleaned
Grit Chambers
o Air injected
Cutters-Shredders
( comminuters)
Pre- Aeration
Sedimentation
Primary sedimentation
before activated sludge
Primary sedimentation
tanks before trickling
filters
Intermediate sedimentation
between multistage
trickling filters
Final sedimentation after
activated sludge
Final sedimentation after
standard trickling
filters
Final sedimentation after
high-rate trickling
filters
Chemical Precipitation
Chlorination S/
Type of wastewater or
effluent :
Raw wastewater, depending
on strength and stale-
ness
Settled wastewater
Chemically precipitated
wastewater
Trickling filter effluent
Activated sludge plant
effluent
Intermittent sand filter
effluent
Operational ^ ^^
Parameters
2/
Bar Spacing in Inches—
1-2
1/2 - 1
1/32 - 1/4
As small as 5/8 -
Flow Velocity: Mteh of Gritf Overflow Rate
0.75 to to\Be Removed gal/sq ft/ day
1.0 ft/sec \35 / 73,000
\g/ 51,000
sX 38,000
V"0\ 25,000
/ Ai^j Requirement :
/ .025 to .05 cu ft/gal
Capacities: , /
0.35 to 25 MGD- _*— — — — —
650-5,200 lb/hr£ ,. *~"~*
Detention Time: Air Requirement: I/
15-45 min. .005 to .2 cu. ft/gal
or 25 - 40 psi
Overflow Rates: I/
2000-6000 gal/day/sq.ft
2/
Detention Time- Overflow Rates
(hr) gal/day/sq ft
0.75 - 1.0 1,500 - 1,000
2.5 600
2.0 - 2.5 600 - 900
2.0 1,000
2.0 800
2.0 800
2.0 800
Weir loading rates:
*-l MGD; 10,000 gal/linear f t -
>1 MGD; 15,000 gal/linear^f t
\
2/
Chlorine Probable Chlorine Chlorinator—
residual : Requirements Capacities
2 mg/1 Ib/day
„ ^ ^ _ mg/1 per 1,000 mg/1 lb/1,000
Contact time : -
persons * persons *
6-25 5-21 30 25
5-20 4-17 25 20
3-20 3-17 25 20
3-20 3-17 25 20
2-20 2-17 25 20
1-10 1-3 15 12
Accumulated Material
(Sludges, etc. )
I/
Cubic feet/MG
3/4 - 3
3-8
5-30
Cubic feet/MG
2-8
Volume of skimmings:
0.1 to 6 cu.ft/MG
or 200 cu.ft/
1000 person/yr
Sludge accumula-
tion is approxi-
mately .038 cu ft/
capita or 3,500
gal/mg of flow
sSludge contains
chemical high water
conteiffc^nd is twice
the volumexproduced
from plain sedi-
mentation ^^^
Scum and grease
accumulated in
contact chamber.
Support Systems
Power for mechanically
cleaned racks,
conveyor belts,
grinders
Power for mechanical
cleaning, cyclone
operations, and for
pumps to supply air.
Conveyor system to
remove grit.
Power :
"•""iTi to 3.5 hp motor
Cleaning units for
dif f users, power
supply for air supply.
Cleaning mechanism
for units without
mechanical scrapers
and skimmers. Sludge
pumps and power supply
for those with pumps
and mechanical
skimmers.
Dosing, mixing,
f locculation; and
sedimentation units;
where existing
sedimentation units
are not being used.
Chlorinators, chlorine
leak detection equip-
ment; baffled contact
tank unless adequate
contact time is
provided in a waste-
water outfall or
conduit. Safety
equipment : Scott
air packs, cylinder
repair kits,
ventilation system.
Chlorine residual anal-
yzer scales,
evaporators, CPRV
* For background information see Appendix C
** For wastewater flow of 100 gpcd
*** For approx. specific gravity of 2.31
I/ Steel
2/ Imhoff-Fair
3_/ 10-State Standards, 1971 edition
4' ASCE Std Manual
5/ Local requirements should prevail
19/20
-------
OPERATIONAL DATA ON SECONDARY WASTEWATER TREATMENT
-------
Table II-2
SECONDARY TREATMENT DATA *
Unit Operations
or Processes
Trickling Filters t
xOperat ionaV— >~^^
t^'S ' Parameters-^ ^N,
y
' Recirculation Rate for
Maximum BOD of Settled
Wastewater
\
\
Loading Rates
Low Rate
gal/day/sq ft 25-100
High Rate
Filter
200-1,000^
Support Systems
= -\
v Dosagin£>tanks
-Recirculation
BOD mg/1 Ratio
130 1:1
170 2:1
220 3:1
260 4:]
' million gal/acre/day 1.1-4.4
Organic Loading
lb/1,000 cu ft/day 5-25
Ib/acre ft/day 220-1,100
8.7-44 >elcjfc>e'pui
power supply
25-300
,100-13,000
Intermittent Depth of sand 3J-4 ft
Sand Filters Head on filter, 5 ft
Stabilization Pond
or Lagoon^ Detention Concen- 4/
1. Large holding reservoir (days)** Depth tration —
- -tabili-ntion oond (months) (ft) (mg/1)
(a) Facultative 7-30 2-5 10-50
(b) High rate 2-6 J-l 100
3. Aerated lagoons 1 or 2 - 14 6-15
4. Anaerobic 30-50 8-10
Final clarification
Following
Low-rate trickling filters
High-rate trickling
filters
Activated sludge (over
2.0 mgd)
Activated sludge (under
2.0 mgd)
Loading 75,000-125,000
gal/acre/day
Solids 2 lb/5 sq ft/day
Ib/acre/day
20-50
100-200
300-500
Overflow Data 3 g/
gals/day/sq ft — *~
800-1,000
800 /"Vs.
*-**T j
800-1,000 ^— ^
800
C Dosing siphon of )
flow distributor )
~
Aerators
Sludge pumps, power
supply for mechanical
sweepers , pumps
reclrculatlon pump
Detention Tine (hrs) for
Overflow Rates & Depth of Tank—'
Overflow Rate Depth ^*^
600 2.1 2.4 3,/0
Package Aeration
Plants
800
1,000
Flow Rate :
1.6 1.8 .X2.25
1.25 1.4/ 1.75
.^
,-*400 gpc/dwelling
or 100 gpc/day
Organic load:
10-20 Ib BODs/1,000 cu ft
of areation tanks/day
Power supply
sludge pumps
Detention
Time for: aeration tank 24 hrs
clarifier 4 hrs
Air Supplied:
2,100 cuft/lb BCD/day
Recirculation rate: 1:1
Activated sludge
System & ponds
(see table)
For background information see App. D.
Unless otherwise noted
I/ Now parallel systems
£/ After 1960, Eckenfelder, O'Connor
3/ ASCE STD manual
4/ Algae concentration in
suspension
5/ 10-State Standards 1971
21/22
-------
Unit Operations
or Processes
Tyjjes of Process
Table II-3 I —
In
QPTTYNTIA DV TPITATTWITTMT HATA APTY VATTTn QT ITnm? OPHP'C'QQ " -
Operational Parameters Loading Rates Support Systems
2/ Loading-
Detention Time- Percentage Recycled Ibs BODs/
Type of Mixing Flow Scheme (hr) Sludge Ibs MLSS Air Requlrements-
Plug Complete Aeration Aeration & Uulti Stage
Flow Mixing Only Sludge Return Aeration
& Sludge
Return
Modified Aeration
(or high rate)
Conventional
Contact Stabilization
scheme 1
scheme 2 A
tO PWO Stage Aeration I
Extended Aeration
Step Aeration
x x 3 or less 10-sc£ 1 or more .41 ft3/gal
x x 1-6 15-755/ 0.2-0.5 .4-1.5 ft3/gal
or ,
768-1000 ft3/lb BOD
x x .5-1.0 50-1502/ 1 0.15-0.2 \ (750 ft3/lb BOD 'N P°wer s"PPly
x x Contact range 1-4 1 0.15-0.2 \ V removed / sludge pumps
Stabilization tank ] \ ^^» ^S air compressors
-^ ' ^-^^^.^ ™~ ~" alr control
x x Contact range f 0.07-0. 15% system
1.5-3.0 \ ^^^a&' sludge
Stabilization tank v— — __— — aeration
f 6-9 ^__ tanks
x x 24 hr 50-200- C /*0. 01-0. 07 •* J
3-8 20-7^ .2-0.5 of /tf500-700/f t3/lb 1\
50 Ibs/lOOOft3 V^TjaDD^removed J
Completely mixed 3 or more 20-10O- 2-.5 C./ SOOft^lbTOD )
Oxidation Ditch (Passover Ditch) Due to limited data at this tine, no ranges for operational parameters or loading rates are possible.
I/ Ib of BOD Ib mixed
liquor suspended solids unless otherwise stated. American City, October 1971
2/ Steel, 1961. Manual for EPA "Up Grading Wastewater T.P."
3/ Minimum air requirement, according to 10-State Standards, Is 1500 cu ft air/lb BODs except extended aeration which Is 2000
4/ Steel
5/ 10-State Standards, 1971
-------
OPERATIONAL DATA ON ADVANCED WASTE TREATMENT
-------
Table I1-4
ADVANCED WASTE TREATMENT DATA*
ffl
V
X
Unit Operations
or Processes
Operational Parameters
Accumulated Material
Support Systems
\VV^\ Chemical/Physical
If Treatment
^
Capacities as for
primary or secondary
clarifiers
From 200 to 900 mg/1
of additional sludge
(for phosphorus removal)
Mixing basin for dis-
persion of added chemicals,
pH measurement and
control equipment
Carbon Absorp-
tion
Contact time: 15 to
45 minutes. Flow ,
rates: 5 to 10 gpm/ft'
From 50 to 120 mg/1
of organic materials
Regeneration furnace
Filtration equipment
(where needed)
to
on
Ammonia
Stripping
Air temperatures above
32°. pH between
10.8 and 11.5
Ammonia is carried off
into atmosphere.
AJ2-- Soma carbonate scale
ind sludge buildup.
Power for forced draft.
A Coupling with
phosphorus removal.
Recarbonation equipment
Electrodialysis
Flow rate: up to
10 MOD. More
A efficient at higher
\ temperatures
Brine stream 10-25%
of feed stream
Electric power for stacks
Brine disposal system
Reverse Osmosis
Flow rate: up to
50 MGD. More effici-
ent at higher
temperatures
Brine stream
10-25% of feed
stream
Power for high pressure
pumps (600 psi)
Brine disposal system
*For background information, see Appendix E.
-------
OPERATIONAL DATA ON SOLIDS TREATMENT
-------
Table I1-5
*
SOLIDS TREATMENT DATA*
Operational
Parameters
Support Systems
Unit Operations
or Processes
6.8-7.2
85-95°F
30 days
12 cu ft/lb
volatile
matter
reduced
Anaerobic
Digestion
PH
Temperature
Detention
Gas production
Heat exchangers
Loading of Heated
Tanks,** Ib volatile
solids per cu ft
per montj
Circulation pumps
o Gas
o Sludge
Sludge produced/ for
Anaerobic Digestion by
Plain sedimentation
Plain sedimentation
and trickling
fi>tfatlpn """"^-^
f Low-rate operation \
V High-rate operation *
and activated sludge
High-rate operation
Conventional operation
Aerobic
Digestion
Sludge
Thickening
Gravity thickener
o Secondary sludge
o Activated sludge-
Flotation
Sludge Drying
Beds for:
o Primary precipitation
o Standard-rate filter!/
o High-rate filter 2/
o Activated sludge!/
o Chemical precipitation
#-' r/s
fjS 9 9
£ 4.4 9
3.6 7
Dissolved oxygen 1.0-1.5 mg/1
Detention times 20-30 days
Overflow Loading
gal/sq ft/day Ibs/sq ft/day
400 8
500 8
Area in sq ft per capita
Open beds Covered beds
1.00 0.75
1.25 1.00
1.50 1.25
1.75 1.35
2.00 1.50
QLG4. -JjJtLvLMA.
U ' »irv4j
<^Ju
-------
CO
o
Table II-6
COMMON SOLIDS TREATMENT DATA*
ffl
Amounts of Chemicals Commonly
Unelutriated Sludge and Yields
Condi-
tioner,
% of
dry
sludge
solids
Type of Sludge CaO FeCl
O
Plain sedimen-
tation (primary)
1. Fresh sludge 10 3
2. Digested
sludge 10 2
0 6
Plain sedimen-
tation and low-
rate trickling
filtration
3. Fresh sludge
mixture 12 3
4. Digested mixed
sludge 12 2
0 7
Plain sedimen-
tation and con-
ventional acti-
vation
5. Fresh activated
sludge 0 6
6. Fresh settled
sludge mixture 0 6
7. Digested mixed
sludge o 8
Dry
Solids
Ib per
1,000
persons
daily
143
89
78
183
117
99
71
195
129
Filter
Capacity
Ib per
sq ft per Cake
hr, dry Solids
basis %
5 32
6 32
6 28
4 28
6 30
6 26
2.5 20
4 22
2.5 22
Employed in
of Vacuum
Required
Filter
Area, sq
ft per
1,000
persons
daily
1.2
0.6
0.5
1.9
0.8
0.7
fl
I D
1.2 *^
2.1
2.1
Conditioning
Sludge Filters
Condi-
Sludge tioner,
Cake, Ib per
Ib per 1,000
1,000 persons
persons daily
daily
450
280
280
650
390
380
350
880
580
CaO FeCl,
O
12 3.6
7.5 1.5
0 4.5
18 4.4
11 1.9
0 6.7
0 4.1
0 11
0 9.7
Support System
Dosing equipment
Power supply
Sludge pumps
Elutriation
tanks
Chemical
storage
*Adapted from Imhoff-Fair, 2nd edition. For background information, see Appendix F.
-------
SAMPLING/TESTING
-------
Ill
SAMPLING
AND TESTING
-------
Section III
SAMPLING AND TESTING
INTRODUCTION
The sampling and testing program described in this section is designed
to determine
» the type of sampling to be done
• the locations of sampling points
• the analyses to be performed for the particular
treatment system.
In addition, recommended storage temperatures and durations are given, as,
well as a list of the laboratory equipment that will be needed to perform •-
the various analyses. Sample forms are included which are intended as
aids for the systematic recording of the results of the various analyses.
The information in this section can be used with the problem/solution
section of this manual (Section IV) either to establish a sampling and
testing program to solve a particular problem involving a particular
process, or to institute an adequate sampling program at a plant lacking
such a program.
A comparison of the type and frequency of tests needed to control the
various processes with the sampling program actually being performed at
the plant site can help evaluate the process control system of the plant.
In the overall evaluation of the plant, this comparison would be used in
ratings of the sampling and testing program, and. the laboratory facility to"
perform necessary tests.
GENERAL
/ (j/4X^us/tf"1 ' ' <--^ w- yjjr. ^ur*
The characterization of waste, whether it be domestic or industrial in J ju^ ^
origin, beg_inswithsampling. A wastewater treatment plant consists of
various components which make up the treatment system. A program of
sampling and testing which measures influent, effluent and'individual
process units on a scheduled basis not only means better plant performance
but can also indicate problems quickly so that immediate Corrective
measures can be taken. ^^ \)
-------
facilities. The treatment plant should be provided with adequate laboratory
facilities for the performance of tests necessary for the proper operation
>f the plant.
Some more sophisticated treatment plants are provided with instrumenta-
tion which allows for constant monitoring of certain treatment processes
and it is customary for this information to be telemetered and recorded
at some convenient location within the plant control building. Telemetered
information can include, but not be limited to, primary effluent pH, final
effluent chlorine residual, aeration tank dissolved oxygen, and sludge
density. Even though the instruments performing these monitoring functions
can be highly reliable, it is recommended that their performance be checked
periodically by analyzing concurrent and identical samples.
THE SAMPLING PROGRAM
A well-organized, effective sampling program must consider several
factors:
• Type and scheduling of sampling needed for the specific
analyses to be made
• Quantity of samples needed
• The most effective sampling locations
• Handling and storage procedures (between sampling
point and testing site)
• Types of sample testing to be done.
Tables III-l and III-2 indicate the common constituents which are
analyzed from the flows of various treatment processes. The matrix
(Table III-2) also indicates points in the treatment system where samples
should be taken. The indicated sampling frequencies are minimum values and
are dependent on or can vary with size of plant and staff, complexity of
the system, the nature of the waste handled, and on the effluent require-
ments placed on the facility.
The test indicated should be performed as frequently as indicated in
accordance with the prevailing requirements of the agency governing waste
discharge within the area in which the plant is located. Every effort
should be made to perform the tests in accordance with their scheduled
frequency. A test with a "weekly" frequency should be run at a regular
hour and day of the week.
32
-------
Table III-l
PROCESS TESTING GUIDE*
PROCESS
A/&A/VAJ
aA
)°£ii AI/W
Removal f
^
• P R I
y
/ Primary
Sedimentation
TEST l %J),4
-------
"»
Table III-2
EQUIPMENT TESTSSG MATRIX*
EQUIPMENT NEEDED •*
* '11
r ^Y* 4
CONSTITUENTS 'tt| ^J
TO BE ANALYZED U ^
\ Volatile Solids
I Total Solids
' ^Settleable Solids
Total Sulfides
< Biochemical Oxygen Demand
Chemical Oxygen Demand
•^ Suspended Solids
Dissolved Oxygen
*X Chlorine Residual
ell-fa'* W MPN Coliform
Volatile Acids
Alkalinity
Gas Analysis
Grease
Total Organic Carbon
Turbidity
Volatile Suspended Solids
Total Phosphorous
MBAS
Sludge Filterability
Ash Analysis
Jar Test
Apparent Density
Iodine Number
f—t~erc~ —
^hSfheTms—
Calcium Content
Ammonia Nitrogen
Organic Nitrogen
Nitrate Nitrogen
Heavy Metals
/ «J
Atomic Absorption.
600° C Muffle Furnace
103° C Drying Oven
Analytical Balance
Imhoff Cone 3
• • •
• •
•
• •
• •
• • •
• •
•
•
•
A-^ ^
* ^ Is
V i }; ~4
\
-------
Types of Sampling
Sampling can be either of two types:
1. Grab. This type of sample is taken when wastewater does
not flow continuously, when appearance of discharge,
changes rapidly, and when making sure that the composit
sample isn't masking extreme conditions of the—was
/''/y \
It is also used when test samples cannot b^ inaxedj such
as when testing for residual chlorine, dis^soi-vea oxygen,
or pH.
2. Composite. With the widely varying characteristics of
waste, this type of sampling provides a representation of
wastewater over a period of time and can be composited
on the basis of proportional flo,w or the same amount
being collected at every internal during the sampling
period. Composites^ should bo/corrected as specified in
Standard Methods.
Location of Sampling Points
• ' > -n.
J ^
Samples should be taken only jfhere the wastewater is well mixedM \t
large particles are found in the/sample, they should be broken up to make
a more homogeneous sample. Dejrosits or growths of floating material
which have formed at the samRiing point should not be included in the
sample.
Quantity of Sample
^,
In order to determime the correct^amount of sample to be collected, the
past flow records of the plant should be analyzed to determine the daily
average flow. The amount of the composite sample to be collected at a
given period should/be proportional to flow of wastewater at that time.
Then determine thar quantity of sample needed for analysis; 1 liter is
usually sufficient; never try to work with less than about 200 ml.
Handling and SJrorage of Samples
Samples sfhould be tested as soon as possible. If testing must be
delayed, th/n adequate storage must be provided. Table II1-3 recommends
appropriatiS storage temperature and duration in terms of the test to be
performed/on the stored sample.
35
-------
Table II1-3
STORAGE TEMPERATURE AND TIMFP
I/
ANALYSIS
Total solids
Suspended solids
Volatile sus-
pended solids
COD
BOD
TEMPERATURE
4°C
4 C
4°C
TIME/
/
Up /o
several
d/ays
/Up to
several
days
Up to
several
days
Up to one
day in com-
posite
sampling
systems
TEMPERATURE
<^
0°C f
o°c
o°c
TIME
f^l
No storage
No storage
Unlimited
Lag develops,
must use
fresh
sewage
seed
Source: Agardy, F.J., aria M. L. Kiado, Effects of Refrigerated Storage on
the Characteristics of Waste, 21st Industrial Waste Conference,
Purdue Univer/ity, May 3-5, 1966.
I/For more .detailed preservation techniques, see Analytical
~" Quality^Control, EPA Chemical Methods, or Standard Methods
Test Records
In order that the data developed through the plant sampling program can
be properly utilized to gage plant performance, it is necessary that it be
systematically recorded and filed for ready reference. The most practical
means of satisfying this requirement is to prepare convenient forms on
which these data can be recorded. These forms should be prepared to fit
the particular operating conditions at each individual plant. The data
should be recorded chronologically on these forms and should be organized
so that each set of data can be utilized to evaluate a particular aspect
of the treatment process. Proper recording of sampling data will allow
for more efficient and expedient solution of operational problems. Several
examples of operational forms are included at the end of this section
which can be utilized for the recording of analytical data pertinent to
the treatment process.
36
-------
In addition to recording the data on forms, graphing of pertinent
operating parameters may be appropriate and desirable for visual presenta-
tion.
For additional information on
sampling and testing, see:
State of Washington Wastewater
Plant Operator's Manual
Operation of Wastewater Treatment
Plants: A Field Study Training
Program, EPA
Effects of Refrigerated Storage
on the Characteristics of Waste,
21st Industrial Waste Conference,
Purdue University
Standard Methods, 13th Ed
Collection, Storage, Transportation
and Pretreatment of Water and
Wastewater Samples by Sanitation
and Radiation Laboratory,
California State Dept. of
Public Health
MOP 11
MDP 18
37
-------
SAMPLING PROGRAM FREQUENCY AND LOCATION
PARAMETERS TO SAMPLE
PROCESSES
PRE TREATMENT
GrU Removal
PRIMARY TREATMENT
Sedimentation
SECONDARY TREATMENT
Activated Sludge
Trickling Filler- Single Stage
Trickling Filter -Two Stage
Oxidation Ponds
Final Sedimentation
Package Aeration Plants
Imhoff Tanks
DISINFECTION
Chlorination
SOLIDS HANDLING
Thickening
Digestion
Centrifuging
Vacuum Filter*
Incineration
ADVANCED WASTE
TREATMENT
GREASE
©®*
,
See Tab
See Tafal
I
a.
©©»•
mm,
©o
©d
©d
©©©„
©©"
©<
@®»
©<
, Ml-l.
e Ill-l.
1
-t
©d
©d
©G@d
©@"
®-
©y
/
O
§
©O".
©"
I
©-
CHLORINE RESIDUAL
®d
®.'
©d
©d
©d
©d
FREQUENCY
daily d
weekly w
monthly no
biweekly b-w
bimonthly b-m
when in
operation q
SAMPLING POINT
Q raw sewage
(2) final effluent
^ proceo effluents
@ primary effluent
(V) secondary effluenl
NOTE: Thi* ii a minimum
channel with plant
:diote effluent
® i»l
© c(orifi«d efflu«i
®/filt.red effluent
.fluent
r® inlluent or .Fflu.nl
ing program and U subject to
ind operational problemi.
^§) digestor effluent
© row.ludo.
(Tg) primary sludge
(f|) secondary sludge
© above tludge blanket
Qj) digested sludge
@ receiving water
-------
SAMPLE FORMS TO BE USED WITH
A SAMPLING AND TESTING PROGRAM ANALYSIS
AND EVALUATION
Forms to be developed and inserted by field inspectors.
39
-------
PROBLEMS/SOLUTIONS
-------
IV
COMMON OPERATING
PROBLEMS and
SUGGESTED SOLUTIONS
-------
COMMON OPERATING PROBLEMS
and
SUGGESTED SOLUTIONS
INTRODUCTION
There is a. variety of common operating problems which may occur period-
ically and prevent the proper processing of wastes by a treatment plant.
The purpose of this section is to properly identify the problem by
defining the indicators. Once the problem has been identified, certain
monitoring, analyses and/or inspections must be performed prior to making
a decision as to which corrective measures should be utilized. In some
cases, the data-gathering process can be a simple visual observation and in
other cases it can involve rather intricate sampling and laboratory pro-
cedures. The resulting information should then be systematically utilized
to make a determination on which of the corrective measures should be
implemented.
The problems discussed in this section are those which occur rather
frequently in practice and the suggested solutions have been, for the most
part, accepted procedure in the industry. There may be times when the
suggested corrective measures do not correct the problem, or a problem
may exist which does not fit into the common category. In a case such as
this, it is prudent to seek expert advice on the subject prior to under-
taking any course of action. The information utilized in development of
the indicators and solutions reflect the present state-of-the-art; as
information from new technical advances becomes available, this section
will be updated.
41
-------
PROBLEM INDEX
Page
I. PRETREATMENT
PUMPING PLANTS AND INFLUENT SEWERS
Surging of plant influent 49
Accumulation of solids or scum in wet wells 51
Odor source in wet wells ~52
SCREENING AND SHREDDING
Accumulation of rags and debris for disposal 53
Excessive grit in bar screen chambers 54
Odor source in grit chamber ^—•66-
Shredded screenings clogging pumps 56
GRIT HANDLING AND REMOVAL
Grit removed has high organic content 57
GENERAL
Industrial waste is inadequately pretreated 58
II. PRIMARY TREATMENT
PRIMARY SEDIMENTATION TANKS
Floating, gaseous, or septic sludge in tanks 59
Low settleable solids removal efficiency 60
Erratic operation of sludge collection mechanism 61
Low scum (grease) removal 62
Tank contents turn septic 63
43
-------
Page
III. SECONDARY TREATMENT
ACTIVATED SLUDGE PROCESS
Sludge bulking 64
Erratic sludge volume indexes 65
Difficulty in maintaining balanced mixed liquor
dissolved oxygen 66
Excessive foam in aeration tanks 67
Digester supernatant and/or centrifuge centrate
upsetting activated sludge process 68
Unable to maintain balanced food/micro-organism
ratio in aeration unit 69
Facilities inadequate for disposal of waste activated
sludge 70
Uneven hydraulic and solids loading of aeration tanks 71
TRICKLING FILTERS
Ice buildup on media 72
Filter odors 73
Fly nuisance in vicinity of filter 74
Clogging and ponding of filter media 75
Clogging of distributor nozzles causes uneven
distribution of flow on the filter surface 76
OXIDATION PONDS
Excessive weeds and tules 77
Pond odors 78
Low pond dissolved oxygen 79
FINAL SEDIMENTATION
Sludge or pin floe flowing over weirs 80
Erratic operation of scraper mechanism 81
44
-------
Page
IV. ADVANCED TREATMENT
CHEMICAL COAGULATION AND FLOCCULATION
Chemical coagulants utilized for settling or
dewatering sludges through recycling cause
floating sludges in primary sedimentation tanks 82
AMMONIA STRIPPING
Freezing in ammonia stripping tower 83
Formation of calcium carbonate scale on ammonia
stripping tower fill and structural members 84
FILTERS
Filter backwash wash water hydraulically overloads
and upsets clarifiers 85
MICROSCREEN
Fouling of fabric with grease and solids 86
Microscreen effluent exhibits higher suspended
solids content than influent 87
ACTIVATED CARBON
Mechanical fouling of columns 88
V. DISINFECTION
CHLORINATION
Insufficient chlorine gas pressure at the
chlorinator with all cylinders connected
to gas phase. 89
Insufficient chlorine gas pressure at the
chlorinator 90
There is no chlorine gas pressure at the
chlorinator, when apparently full chlorine
cylinders are connected to the chlorine
supply system. 91
45
-------
Page
Impossible to operate chlorinator because
rotameter tube ices over and feed rate
indicator is extremely erratic. Chlorine
supply is from ton containers connected
to the gas phase. 92
Chlorinator will not feed any chlorine even
though all systems appear normal. 93
Chlorine gas is leaking from vent line connected
to external chlorine pressure reducing
valve (CPRV) 94
Inability to maintain chlorine feed rate without
icing of chlorine supply system between
external chlorine pressure reducing valve
and chlorinator. (Equipment consists of
evaporator, external CPRV and the
chlorinator.) 95
Chlorination facility consisting of evaporator-
chlorinator combination with external chlorine
pressure reducing and shut-off valve is unable
to maintain water-bath temperature sufficient
to keep external chlorine pressure reducing
valve in open position. 96
Inability to obtain maximum feed rate from
chlorinator or chlorinators with adequate
chlorine gas pressure at chlorinator. 97
Inability to maintain adequate chlorine feed rate 98
Inability to obtain maximum or proper feed rate
from chlorinator with adequate gas pressure
at chlorinator. 99
Excessive chlorine odor at point of application 100
Chlorinator will not feed enough chlorine to
produce a proper chlorine residual at the
sampling point. 101
Wide variation in chlorine residual in effluent
as determined by hourly chlorine residual
determinations. 102
Chlorine residual analyzer recorder controller
does not appear to control the chlorine
residual properly. 103
46
-------
Page
Chlorination system consists of either
compound-loop control or direct residual
control and system does not appear to be
controlling properly. 105
Coliform count does not meet the required
disinfection standards set by regulatory
agencies. 106
Coliform count does not meet the required
standards for disinfection. 107
Plant effluent does not meet toxicity requirements
because chlorine residual to achieve proper
disinfection is at too high a level. 108
VI. METERING
Plant meter unreliable 109
VII. SOLIDS HANDLING
SLUDGE THICKENERS
Odor from thickener 111
Thickener contents do not settle 112
Sludge pumped from thickener has low solids
concentration 113
SLUDGE DIGESTION (Anaerobic)
Scum blanket in tank 114
No digester gas production 115
Increase in volatile acid/alkalinity ratio
in digester 116
Foam in digester 117
Low reduction of volatile solids in digester 118
High percent solids in digester supernatant 119
CENTRIFUGING
Low solids recovering rate 120
47
-------
VACUUM FILTERS
LowOsolids
cove]
INCINERATION
Abnormally high temperature in furnace
Abnormally low temperature in furnace
High oxygen level in furnace stack exhaust
Low oxygen level in furnace stack exhaust
SLUDGE LAGOONING
Excessive solids carried over from lagoon
supernatant to plant influent
Odors from sludge lagoons
Page
121
122
123
124
125
126
127
48
-------
»sx»VjA l^Ci .
I. PRETREATMENT - Pumping Plants
SURGING OF PLANT INFLUEN
Intermittent flooding of.'weirs and structures.
Monitoring,
Analysis
and/or
.If a main sewage lift station pumps
ck for frequent starting and stopping of pumps or more
than one pump operating at one time (out of phase) during
a pumping cycle. -fg|» L/tAttLJ (& (fn^&fb M"ff/j/^^
,-^M~- ||j~— ^ | n»t lAAf
If influent flows to the plant by gravity through a main
trunk, check depth of flow in connecting sewers if
channel iSK uniform or monitor flow with a portable flow
If surging occurs during rainfall, record relation of
surging to duration of rainfall; and record or obtain
rainfall intensity if possible.
Surging from gravity influent line indicates a major
'pump/station discharge into a connect/ng sewer. Review
•water depth and/or/portable flow meter data to determine
so/rce of flow. '
Intermittent starting and stopping or recycling of main
influent pump station or stations indicates improper wet
well sensor adjustment fy^ tha_t±he hydraulic capacity of
the station has been exceeded.^ Adjust level sensors for
'a more desirable pumping cycle. If possible, install
variable speed pumps units for uniform flow into
treatment plant; or install surge tank.
Heavy surging or hydraulic loading of treatment plant
^treating waste from a separated system during periods of
rainfall indicates illegal-connections to system
s catch basins, yard drain, or roof downspouts.
"Smoke bomb" sanitary sewer system to determine source
of illegal connections.
Heavy surging or hydraulic loading of treatment plant
during period of heavy rainfall is caused primarily by
flooding of street areas and water, entering the system
through manholes, broken lines, etc. Seal all manhole
covers in high risk flood areas and patch all cracks in
manhole structures with an epoxy water resistant compound.
49
-------
I. PRETREATMENT - Pumping Plants and Influent Sewers
Problem
SURGING OF PLANT INFLUENT
Indicators
nitoring.
Analysis
and/or
Inspection
Corrective
Measures
1. Intermittent flooding of weirs and structures.
2. Pl_ant efficiency treating wastewater drops sharply
for short period of time.
3. Flow meter records intermittent high and low peak flows.
4. Excessive suspended solids in overflows.
1. If a main sewage lift station pumps effluent to plant,
check for frequent starting and stopping of pumps or more
than one pump operating at one time (out of phase) during
a pumping cycle.
2. If influent flows to the plant by gravity through a main
trunk, check depth of flow in connecting sewers if channel
is uniform or monitor flow with a portable flow meter.
3. If surging occurs during rainfall, record relation of
surging to duration of rainfall; and record or obtai
rainfall intensity if possible.
Surging from gravity influent line indicates a major pump
station discharge into a connecting sewer. Review water
depth and/or portable flow meter data to determine source
of flow.
Intermittent starting and stopping or recycling of main in-
fluent pump station or stations indicates improper wet well
sensor adjustment or that the hydraulic capacity of the sta-
tion has been exceeded. Adjust level sensors for a more
desirable pumping cycle. If possible, install variable
speed pump units for uniform flow into treatment plant; or
install surge tank.
Heavy surging or hydraulic loading of treatment plant treat-
ing waste from a separated system during periods of normal
rainfall indicates illegal connections to system such as
catch basins, yard drain, or roof downspouts. "Smoke bomb"
sanitary sewer system to determine source of illegal
connections.
Heavy surging or hydraulic loading of treatment plant
during period of heavy rainfall is caused primarily by
flooding of street areas and water entering the system
through manholes, broken lines, etc. Seal all manhole
covers in high risk flood areas and patch all cracks in
manhole structures with an epoxy water resistant compound.
50
-------
Problem
Indicators
I. PRETREATMENT - Pumping Plants and Influent Sewers
/I ,\ K " ^
ACCUMULATION OF SOLIDS OR SCUM IN WET WELL
&>
r$r
Monitoring,
Analysis
and/or
Inspection
Corrective
Measures
Scum blanket in wet well
t
^Pffiffi
iment «/ A teWf *
mproper operation ofl\level sensingf/equipment
1. Sound wet well with a pole to determine solids level.
2. Measure/owet well draw .downd
pumping cycle.
3. Ascertain relation or pump suction piping to floor of
wet well.
4. Determine elevation of inlet piping.
5. Look for dead spots in corners and structural cracks
' ^J&L
i where sludge can^ccumulate,
* fad ^^a^/Lob^^
i.
Start pumps manually, being careful not to break suction,
and pump wet well down to lowest possible elevation while
breaking scum blanket with a high pressure water hose.
2. Check pumping level and determine if more of a drawdown
can be allowed for in order to remove more of the
^floatable materials.
If one or more influent line^come in at a higher elevation
than the pump suction inlet, set level sensor so drawdown
will allow for spillage of fresh wastewater onto the scum
blanket. The resultant turbulence could assist in
breaking the blanket.
4.
If this is a persistent problem install air diffusers in
wet well with comp-ressors--wixed_^jo_Qpe^aj;.e-^in—t-andeiifwi't-h-
the—pumps.. Diffused air will assist in placing the
solids in suspension ^and c/urtail thf development of a
scum blanket. /fD A
£)
\
^ *
51
-------
I. PRETREATMENT - Pumping Plants and Influent Sewers
Problem
Indicators
ODOR SOURCE IN WET WELL
i
2.
3.
Monitoring, 1
Analysis
and/or
Inspection
3.
4.
5.
6.
7.
Corrective 1.
Measures
3.
4.
Odors of hydrogen sulfide origin
Corrosion of iron work and concrete
Black color observed in liquid or solids
I
Hang hydrogen sulfide (lead acetate) indifl
tiles in wet well. (}W»-£- \X) V-
Mf-we-tv wgfi ah(i analyze for total
Check for floating solids in wet well. /
Run dye test on influent sewer or sewers to determine
velocity of waste flow and travel time to wet well.
Check temperature of wastewater in wet well.
Check pump invert position and condition.
Check passage time in the interceptors at flow velocities.
Low velocities (less than 2 ft/sec) are an indication
that solids are being deposited in influent sewer and
sulfides are being formed and released in the wet well.
increased in the sewer or influent must
be continuouslyCreated upstream with chlorine or copperous
to pi?olT±bi-fe~fefee**aevelopment of hydrogen sulfide gas.
If the source of hydrogen sulfide is in the wet well and
not the influent sewer, increase pumping cycle for more
frequent removal of solids.
Install air diffusers in wet well to keep wastewater fresh.
Install blower and gas scrubber for the oxidation of the
gases and exhausting to the atmosphere.
Dose wet well with£hyperchloride)on' a periodic basis to
suppress the formatiotf"•crC-irygrogen sulfide.
52
-------
I. PRETREATMENT - Screening and Shredding
Problem
Indicators
Monitoring,
Analysis
and/or
Inspection
ACCUMULATION OF
DEBRIS FOR DISPOSAL
Large amount' of rags and debris*accumulated-.on plant
site gives off obnoxious odors and attracts \flies and
other insects.
.
stimate volume '(cubic feet) of rags and debris removed
eacB day-in PE9.pprjtJ.oii to flow.
ine
v_ ^
exposed material Ts allowed to accumulate
Check disposal method used.
Corrective 1. Arrange for local refuse or garbage company to pick up
Measures rags and debris on a daily basis and dispose of them in
a sanitary fill. ' .——"^
2. Store rags and debris in closed containers whenever
possible. \
3. If incineration facilities are available on plant site
or at some other convenient location, burn them. Care
must be taken to see that /the emission from the
incinerator meets location air pollution control
requirements.
4. Rags and debris can be disposed of on the plant site if
sufficient land is available for a fill and cover
tion.
If none of the abokve
debris can be grou
equipment and retu
should only
shrejdded
and i
thods pro
up by instal
d"'to the pla
a last re
ay cause p:
feasible, rags and
the proper
flow. This method
since ground or
in pumping
53
-------
I. PRETREATMENT - Screening and Shredding
Problem
Indicators
Monitoring,
Analysis
and/or
Inspection
EXCESSIVE GRIT IN BAR SCREEN CHAMBERS
Surging * in chamber-due
— l-r-TrSurging
<2tAj8j
incr
i-h waterVJLevel.
2. I/ow removal off grit by degritting equipment
-i y
oJ—
1. Sound chamber with flat board at end of pole to determine
depth of grit.
2. Determine velocity in chamber by timing a dye release
from one end of chamber to the other.
3. Check plans and probe bottom of chamber to determine
whether there are any irregularities in chamber bottom
slope.
4. Check channel when dewatering for regularly scheduled
maintenance.
Corrective
Measures
1.
2.
3.
If velocity in chamber is less than 2 ft/sec, flush
chamber regularly with high pressure water hose. If
slide gates are available at inlet end of chamber,
throttle gates to jet flow along chamber bottom.
Remove irregularities or reslope chamber bottom; if
possible, to increase velocity.
54
-------
I. PRETREATMENT - Screening and Shredding
Problem ODOR SOURCE IN GRIT CHAMBER
Indicators 1. Odors of hydrogen sulfide origin
2. Corrosion of metal work and concretx
Monitoring,
Analysis
and/or
Inspection 3.
1.
2.
4.
Corrective
Measures
6.
7.
1.
2.
3.
Hang hydrogen sulfide (lead acetate) tiles in chamber
Check velocities through grit chamber
Check volatile solids content of the grit.
and/3inaly/6fe foi\to,ckl
arid /dijfsSlteedy siW tide.
-------
I. PRETREATMENT - Screening and Shredding
Problem
Indicators
Monitoring,
Analysis
and/or
Inspection
SHREDDED SCREENINGS, CLOGGING PUMPS
1. Rope-like rags and debris wrapped around pump impellers.
2. Pump suction lines plugged with "bundles" of rags.
vy
3. Excessive pump or drive treating and power requirements.
4. Appearance of chunks larger in size than usual in
the shredder discharge.
1. Install pressure gages on discharge side of pump and
check pressure daily.
2. If pump discharge line visible, check flow daily.
3. Check power input, bearing heat pressures on inlet
and discharge sides.
4. Check driver speed and power train for power use and
delivery to the shredder.
Do not shred screenings and return them to flow. Remove
them either mechanically or manually and dispose of them
bv burial.
Check cutters periodically on all barminutors,
comminutors, and other shredding equipment for sharpness.
Back flush pumps, periodically if possible.
If necessary, modify pump type, inlet protection or
prior protective devices to avoid recurred plugging.
Upgrade screening and grit removal operation.
56
-------
I. PRETREATMENT - Grit Handling and Removal
Problem
Indicators
Analysis
and/or
Inspection
Corrective
Measures
GRIT REMOVED HAS HIGH ORGANIC CONTENT
1.
2.
3.
Monitoring, 1.
2.
3.
4.
3.
4.
Grey color
Odors from
Greasy fe
with^excessive components
I
Run volatile solids test on grit daily.
Check discharge pressure on cyclonic grit removal
equipment.
Check velocities with dye releases in grit chambers.
If grit chamber is aerated, check air flow rate to
chamber.
Visual examination of grit and identification of
origin of grit materials.
Keep pressure on cyclonic grit removal equipment at
an acceptable range (usually between 4 and 6 psi) by
governing pump speeds.
Increase velocities in grit chambers by whatever
means possible.
Adjust air accordingly.
Check inlet and outlet controls, baffles and
mechanical equipment; adjust and repair and keep
clean.
57
-------
I. PRETREATMENT - General
Problem
INDUSTRIAL WASTE IS INADEQUATELY PRETREATED.
Indicators
1. Discoloration of influent
iSterTTrTZtftionJof biological treatment.
esses
3. Digester upsets
.4. Change in influent odbi
5. Unusual amounts of solids in influent
Monitoring,
Analysis
and/or
Inspection
1. Constantly monitor influent for pH above 8.0 or below 6.0
2. Check pH of raw sludge.
3. Run heavy metal tests on influent.
4. Check influent temperature.
5. Run settleable solids test.
6. If toxic flow is constant, attempt to trace source
upstream of treatment plant.
7. Run C.O.D. test on contaminated effluent and compare
results with normal plant loading.
Bypass all biological treatment processes to parallel
units as soon as contaminant has been detected.
Isolate and dispose of all contaminate sludges.
If digesters show increases in volatile acids because of
contaminated sludges, see Section VII(b) for corrective
measures.
If activated sludge process has become contaminated,
dispose of floe and restart process.
Institute program of source control (industrial waste
ordinances).
58
-------
II. PRIMARY TREATMENT - Primary Sedimentation Tanks
Problem
Indicators
Monitoring,
Analysis
and/or
Inspection
FLOATING. GASEOUS. OR/SEPTIG SJLUDGE
V . Mr. t
Corrective
i.
2.
loating material! in ta
deadspots ortin sgum troughs
igin
Dewater tanks and check sludge collector mechanism
(flights, chains and scrappers) for wear and tear.
If total solids of raw sl&dge analyzed a
cycle is over 2%, increase duration of pumping cycle,
preferably with a timer.
If sludge collector mechanism shows signs of wear during
'inspection, repair or replace.
Certain chemicals \ sutin\ as alum, used in\chemical
treatment, .cause floatine sluage afVthis chemical is
recirculated tW the, primajjy sedimentation rcanks. Change
operating/procedures or chemicaMis usedyl
Long detention in sludge hoppers favors production
of a sludge that readily slips.
59
-------
II. PRIMARY TREATMENT - Primary. 'S«Mn.mentation Tanks
Problem
Indicators
LOW SETTLEABLE SOLIDS JlEMfcVAL EFFICIENCY!
^
A
iAtj-A™ ^-rj^ £R
2. Percent settleable solids removal below 95%
Monitoring,
Analysis
and/or
Inspection
Corrective
Measures
6.
1.
2.
3.
Run settleable solids test (Imhoff Cone) during times of
day where there are appreciable changes in plant flow.
Check raw sludge removal pumping cycles and duration of
pumping period.
Dismantle and/or inspect raw sludge pumps an
collection mechanism for wear and tear.
Check tank inlets with relation to the tank ^outleYs. If
baffles have been installed on the inlets, dewater the
tanks and check their condition.
Calculate theoretical detention time, weir overflow
rates, and surface loading rates and compare all data
with design criteria. h v . - ft * lu/j
Try a dye test to estim^reWlow^trfrougntime. Check
for density stratification due to significant tempera-f
ture or density difference top sto bottom
If efficiency*of removal drops during peak or increased
plant flows, the hydraulic capacity of tanks has probably
been exceeded. Refer problem to operating agency
engineering staff.
Repair all worn raw sludge pumps, parts and sludge
collector mechanism.
Damaged or missing inlet line baffles could cause tank
short circuiting whereby increased velocities from one
end of the tank to the outlet end cause settleable matter
to remain in .suspension. Tleplace or repair baffles.
60
-------
II. PRIMARY TREATMENT - Primary Sedimentation Tanks-
Problem
ERRATIC OPERATION OF SLUDGE COLLECTION MECHANISM
Indicators
Monitoring,
Analysis
and/or
Inspection
Corrective
Measures
1.
2.
Frequent replacement of broken sheer pins on chain
driven collector mechanisms.
Frequent torque switch activated alarms on concentric
driven clarifier equipment.
Visible slippage or "stuttering"
collection mechanisms.
of clarifier sludge
Check all drives for gear wear.
Dewater tank and check chains and sprockets for wear
see that chains have not come off sprockets. &JC4£>
Check to see that rags and debris have not entwined
themselves around sludge collector mechanism.
Check dewatered tanks for excessive bottom deposits of
sand, rocks and other inorganic material.
Sound bottom for excessive^ accumulation o£ sludge. . .^ _ ,
V> /lAs&Ot
Repair all worn sludge collector equipment and drives.
If rags are a problem, make provisions for removal of
all rags and debris as part of the pretreatment process.
If sand and rock deposits on the tank bottom are a
problem, provide adequate screening and grit removal as
a part of the pretreatment process.
If sludge accumulation is a problem, increase frequency
of pumping raw sludge from tanks.
61
-------
II. PRIMARY TREATMENT - Primary Sedimentation Tanks
Problem
Indicators
LOW SCUM (GREASE) REMOVAL
Monitoring,
Analysis
and/or
1.
2.
1.
3.
4.
5.
Visible grease particles being discharge/
effluent *
serve if wooden flights making a return travel on tank
surface carry grease particles adhered to them under scum
troughs at the discharge end of the tanks.
ickup wiper blades.
If possible, lower return wooden flight to beVLow wateh
surface so grease particles do not adhere to them.
Install
surface
surface
|rays to direct grease particles on tank
!m troughs. Water spray should not break
n on water surface.
If scum removal is done manually and intermittently,
continuous removal equipment should be installed.
Excessive water in scum pits should first be removed by
pumping from bottom of pit to plant headworks and then
the concentrated scum can be pumped to a digester or an
incinerator.
Efficiency of scum removal in plants receiving a high
grease loading can be increased by the addition of
flotation or evacuator equipment.
Since grease particles normally in suspension tend to
agglomerate into larger particles after being dosed with
chlorine, chlorine contact tanks should be provided with
grease removal equipment.
Pump scum pits down on a regular basis so as not to
cause scum overflows back into the clarifier.
Clean and replace all worn wiper blades.
f/
62
-------
II. PRIMARY TREATMENT - Primary Sedimentation Tanks
Problem TANK CONTENTS TURN SEPTIC
Indicators 1. Tank contents are a dark color
r
2. Hydrogen sulfide odors emitted from tanks
Monitoring,
Analysis
and/or
Inspect
/ \
RuA to±al/antf Idis^bJved^ulfi
taAk/Kj/fuent
teib
Run DO test.
Check quantity and total solids of all inflows into
tank from other plant processes such as digesters
supernatant, thickener overflows, centrifuge con-
centrates, etc.
f tank influent contains high dissolved and totalj
sulfides, influent is septi<
oorroot-problom.. a4~&g>u-pee..
If tank influent pH is below 6 or above 8, toxic waste
is being discharged yit^O|Dlant a^nd mpfctlbe oprMkcted a
the source. M tyUtAwijtf /$A^4[U4AA H?P
If discharges rrdmSother nJWfnt processes contain
excessive total soli&sa«ncl exceed 5% of the daily tank
.1)inflow, the sedimentp^ba».^ank is being overloaded. If
\possible, reduce n^re of precede flows to sedimentation
tanks or pretre-er flows by aerating <•>]- fhinri patjng them
If possible divert or find other means of disposal for
supernatant or centrates.
tX?
63
-------
III. SECONDARY TREATMENT - Activ
3. Filamentous growths in mixed liquor
Monitoring,
Analysis
and/or
Inspection
1.
2.
3.
4.
Check mixed liquor for low pH and low dissolved
Check sludge age, food/micro-organism ratio, or mean
cell residence time.
Run settleability test and check for separation of
floe in graduated cylinder or use Mallory Direct
Reading Settleometer.
Check aeration period.
•"lir rli' fnr TOPI ind-jff
Corrective
Measures
If possible, reduce organic loads on aeration
tanks affected.
Add digested sludge (that has been aerated for some
time) to aeration tanks.
Dose the aeration tanks with alum or ferric chloride
together with lime.
TeTOrTT activated sludge.
sludge age and air rate -jrg^stojj ^nili'lf icatjxnr;
Increase sludge age by regulating waste sludge rate.
Increase or correct low dissolved oxygen or pH in
aeration tank.
Increase aeration period by placing another aerator
operation if possible or reduce the return sludge
te by thickening the return sludge concentration
by coagulation.
Control filamentous growth by increasing sludge age
or supplementing nutrient deficiencies.
inimum
64
-------
III. SECONDARY TREATMENT - Activated Sludge/Process
ERRATIC SLUDGE VOLUME INDEXES
Indicators
1. Pin floe visible in final clj^ifiers overflow
2. Poor settling characterisj^cs of mixed liquor
lids in each aerat
Monitoring,
Analysis
and/or
tleability test in each aeration
Inspection
the point floe is a recurrent
result of toxicants.
Determine^whe
situation or
Regulatsr wasting to decrease suspended solids
mixed Xiquor .
Chlflfrinate return activated sludge.
crease-solids loading to aeration tanks.
Make appropriate adjustments to obtain a less
oxidized sludge.
65
-------
III. SECONDARY TREATMENT - Activated Sludge Process
Problem
Indicators
DIFFICULTY IN MAINTAINING BALANCED MIXED LIQUOR
DISSOLVED OXYGEN AN AERATION^TANK
Monitoring,
Analysis
and/or
Inspection
Corrective
Measures
N?
\
Intermittent sludge bulking
2. Loss of sludge blanket in secondary clarifier
3. Dark color in the aerator contents
1. Check D.O. concentration in different areas of aeration
tanks during changes in daily flow.
2. Check suspended solids in mixed liquor at different
periods during the day.
3. Run suspended solids test on aerator influent and mixed
liquor to check sludge age.
4. Monitor rate of flow to aeration tanks.
5. Check daily flow variation in loading for excessive
peak demand periods.
1. Lower D.O. concentrations occurring during changes in
plant flow are an indication of excessive loading of
aeration tanks. Increase air supply to tank if possible
by placing another blower into service, etc.
2. Decrease loading to aeration tanks by placing more tanks
into service if possible.
3. Provide controlled air supply to aeration tanks by
interlocking blower speeds to tank D.O. monitoring
equipment.
4. Increase inflow could hydraulically overload the
\ secondary treatment systt
Aportion oiVthe
V ,i-*i
If possible, bypass a
he primary sed
ns to normal
-------
III. SECONDARY TREATMENT - Activated Sludge Process
Problem
EXCESSIVE FOAM IN AERATION TANKS
Indicators
1. Frothing in aeration tanks
Monitoring,
Analysis
and/or
Inspection
1. Check influent for radical temperature changes.
2. Run M.B.A.S. test on influent.
3. Check suspended solids concentration in aeration tanks.
4. Check D.O. concentration in aeration tanks.
Corrective
Measures
1.
2.
3.
4.
If practical, increase mixed liquor suspended solids by
decreasing wasting rate.
Install or operate reclaimed water sprays in aeration
tanks.
Utilize defearning agent.
i**Fr "
Lower air supply while being careful to maintain a safe
dissolved oxygen concentration in aeration tanks.
67
-------
III. SECONDARY TREATMENT - Activated Sludge Process
Problem DIGESTER SUPERNATANT AND/OR CENTRIFUGE CENTRATE
UPSETTING ACTIVATED SLUDGE PROCESS
Indicators 1. Mixed liquor changes from a light to a dark brown
2. Mixed liquor suspended solids decrease sharply during
operation of centrifuge or when sludge is being pumped
to digester
3. Final clarifier effluent increases in turbidity
4. Mixed liquid DO decreased.
Monitoring,
Analysis
and/or
Inspection
1. Run total solids and pH tests on supernatant or centrate
being returned to plant headworks.
2. Check mixed liquor suspended solids during discharge of
centrate or supernatant.
3. Continuously check mixed liquor D.O.
4. Check volume of concentration of recycle flows
relative to total plant flow.
Corrective 1. Program discharges of supernatants or centrates so they
Measures do not coincide.
2. Pump centrates to digester whenever possible.
3. If centrates have high solids content, use flocculants
in the operation of the centrifuge.
4. If supernatant have high solids content, experiment with
supernatanting from a different level in the digester.
5. If possible, pre-aerate centrate and supernatants prior
to discharging them to the activated sludge process.
6. Avoid discharging supernatants from septic digesters to
activated sludge process.
7. If possible, release only small amounts of supernatant
or centrate during periods of low inflow and increase
return activated sludge rates if necessary.
8. Program recycles so that the return load does not
exaggerate peak loading.
68
-------
III. SECONDARY TREATMENT - Activated Sludge Process
Problem UNABLE TO MAINTAIN BALANCED FOOD/MICRO ORGANISM
RATIO IN AERATION UNIT
Indicators 1. Fluctuation in S.V.I.
2. Fluctuation in sludge age.
Monitoring,
Analysis
and/or
Inspection
1. Check S.V.I, at least daily.
2. Check mixed liquor suspended solids at least daily.
3. Check suspended solids in influent and effluent at
least daily.
4. Monitor plant flow, return activated sludge rate, and
waste activated sludge rate.
Corrective 1. Select and operate secondary treatment system by either
MeasuresMean Cell Residence Time, Solids Retention Time,
food/micro organism ratio, or sludge age.
69
-------
FACILITIES INADEQUATE FOR DISPOSAL OF WASTE ACTIVATE
\ (HIGH SUSPENDED SOLIDS IN THE CLARIFIER OVERFLO^)
SECONDARY TREATMENT - Activated Sludge Process
1. High suspended solids in mixeiL_ii£LuJor
2. Increased turbidity in final clarifier effluent '\
3. High solids concentration in digester supernatants
and sludge thickener effluents
Monitoring,
Analysis
and/or
Inspection
1. Check S.V.I, at least daily.
2. Run C.O.D. and suspended solids of plant influent with
and without supernatant and thickener return flows.
3. Check blanket depth level or high and low load periods.
4. Check inlet and outlet baffling for possibility of
short circuiting.
Corrective
Measures"
1.
sludge lS~n«JL_ae.t±*iTi"g '±~n
flnw-nf mini — mirier rn rTii rlrrnrr~nr
thj^skenorj inrrra
dose thickener inflow with coagulants.
3. Re-aerate waste sludge prior to pumping to thickeners or~
discharging to primary clarifiers.
4. Change operation mode of aeration tanks to contact
stabilization if possible.
5. If the sludge doesn't settle satisfactorily, coagulate
with iron or aluminum , but adjust pH *f jmrr>n-nt£% to
keep aerator pH within 6.0-8.5.
70
-------
III. SECONDARY TREATMENT - Activated Sludge Process
Problem
UNEVEN HYDRAULIC AND SOLIDS LOADING OF AERATION TANKS
Indicators 1. Mixed liquor suspended solids in each aeration tank
varies considerably.
2. Dissolved oxygen in each tank varies considerably.
Monitoring,
Analysis
and/or
Inspection
Corrective
Measures
1. Run S-.V.I-. "T.n each tank at least daily.
2. Run mixed liquor suspended solids in each tank at least
daily.
3. Run dissolved oxygen in each tank at least daily.
4. Run suspended solids on influent and effluent.
1. Adjust valves and
tanks when operating u
2. Equalize air flow
air discharge line
es to equalize flow to all
conventional mode.
tanks by throttling valves on
71
-------
III. SECONDARY TREATMENT - Trickling Filters
Problem
Indicators
Monitoring,
Analysis
and/or
Inspection
Corrective
Measurete
H -• ''
'•''<£ ^
ICE BUILDUP ON MEDIA
1. Visible ice formation on filter media
1. Check air temperature. Jr
2. Check recirculation rate to filter.
3. Check flow through filter orifices.
4. Check temperature of wastewater flow to filter.
5. Check filter surface for even distribution of flow.
1.
2.
3.
5.
By regulating amount of recirculation rate, adjust. flow\ -,
to filter to proMbit the formation of ice. AX\£/\ 1 \* \
]'//••'/ ' " n
Adjust flows from orifices and splash plates to reduce
spray effects.
Cover filter to reduce heat loss.es or install a windbreak
to reduce chill factor.
Manually break up and remove major ice formations. .
If possible, add hot water or steam to filter influent.
72
-------
III. SECONDARY TREATMENT - Trickling Filters
Problem
Indicators
Monitoring,
Analysis
and/or
Inspection
FILTER ODORS
/
o
1. Orlnrfl nf tiydrnfrn nrtilfirir nrif-in present
il/
ack slime visible on surface of
1. Ch^Bk^dTssolved and total sulfide of
2. Check filter dj-aiois for stoppages or growths.
&tA/y %{*
3. Check rate (of recireulation to filter..^
U QM^
4. Check ,-for Miter, overflow or jSplashjLr
0
Corrective «," 1. If flow to filter is septic, correct in upstream system
Measures \
. ""
for
l™--~
by aerationor controlled prechlorination
ation. |
...,_. »«^
Vr.""2. Clear under drain system of all stoppages.
A° I* 3. Force air into filter drain system to increase ventilation*
'\ V tk^ through filter media. rJv"'
\ . f\ ff- ' \
4. Increase recirculation rate to filter to increase|D.fO.
and to, slpuglxvc&f f'.feurfaoe "Slime. jSM | | 1 **" |,AA { ^ ( t •( i
5. Keep areas around filters clean of slimes- and growths.
6. Cover filter wi ^h J1Hejrt'i»rna't:p'>"i.fll^air'f1^fixhaust air into
-------
III. SECONDARY TREATMENT - Trickling Filters
Problem
FLY NUISANCE IN VICINITY OF FILTER
Indicators 1. Tiny gnat sized flies becoming a nuisance in plant area
and in neighboring area
Monitoring,
Analysis
and/or
Inspection
Corrective
Measures
1. Inspect grounds for tall grass, weeds and other
sanctuaries for filter flies. »
1. Increase rate of recircuJLation .to .filter^ to waslj. fly
larvae out of filter.
\
\
aslj. f
V*
2. If possible, flood filter for approximately 24 hrs. to
prevent completion of life cycle of flies.
Apply a low dosage of chlorine being careful not to
sterilize filter media.
V/'2-Maintain grounds so as not to provide sanctuaries for
f * flies.
I
74
-------
III. SECONDARY TREATMENT - Trickling Filters
Problem
Indicators
Monitoring,
Analysis
and/or
Inspection
CLOGGING AND PONDING OF FILTER MEDIA
1.
2.
1.
2.
3.
4.
5.
Ponding on filter surface
Intermittent flooding of filter
Check size of filter media for uniformity
Check for cementing or breaking up of media.
Check for fi
or snails in
slime growths, trash, insect larvae,
r media voids.
Check organic loading on filter.
Check hydraulic load on filter.
Corrective 1. If filter media is non-uniform and the smaller pieces
Measures fill the voids, replace the media.
2. Jet problem areas in filter media with a high pressure
water s/pray fron^a stationary distributor.
y to lessen or remove any
Flood filter media
ccumuiations.
growth
poasttTTet
75
-------
III. SECONDARY TREATMENT1- Trickling Filters
Problem
CLOGGING OF DISTRIBUTOR NOZZLES CAUSES
nfj TTITT F.TTTTOT]
Indicators
Monitoring,
Analysis
and/or
Inspectien
Corrective
1.
2.
1.
2.
Uneven sprays from distributor nozzles
Ponding on certain areas of the filter media with
concurrent drying of other areas
ttempt to identify types OT solieqf clogging nozzles.
Check for visible grease particles in waste being
pumped to filtej
.emove and clean all nozzles and thoroughly flush
distributor piping.
Improve primary clarifier skimming to prevent grease
carryover to filter.
Increase detention
settleable and suspend
\
primary tanks to prevent
olids carryover to filter.
76
-------
III. SECONDARY TREATMENT - Oxidation Ponds
Problem EXCESSIVE WEEDS AND TULES
Indicators -1-. Excessive weed and tule growths
2. Mosquito problems in neighborhood of ponds
3. Poor pond circulation
Monitoring,
Analysis
and/or
Inspection
Corrective
Measures
1. Check water depths in selected areas of the pond
Deepen all pond areas shallower than three feet.
Remove all weed and tule growths as soon as they are
visible.
every 10 days.
varY liquid level in the pond
77
-------
III. SECONDARY TREATMENT - Oxidation Ponds
Problem
POND ODORS
Indicators 1. Odors of hydrogen sulfide origin from pond
2. Other objectionable odors
Monitoring,
Analysis
and/or
Inspection
1. Check for blue-green algae growths in pond.
2. Check for scum accumulation in pond.
3. Analyze for total and dissolved sulfides in pond and
pond influent.
4. Check pond pH and pond influent pH.
5. Check DO content in pond at several locations.
Corrective 1. If pond influent is septic, correct situation upstream
Measuresby aeration or controlled prechlorination.
2. If possible, aerate pond with mechanical aerators.
3. Remove or break up all scum accumulations.
Sir
5. If pond is septic, divert flow from aerobic pond to
or pump high D.O. make up water to it.
6. Add sodium nitrate to pond.
78
-------
III. SECONDARY TREATMENT - Oxidation Ponds
Problem
Indicators
LOW POND DISSOLVED OXYGEN
1. Low algae growth in pond
2-,
Traoo hydge§eB-&u3^£d.de..odor.
Monitoring,
Analysis
and/or
Inspection
3. Grey color of pond
Check all areas in pond for adequate D.O.
2. Monitor flow into pond and calculate average daily
detention time in pond.
3. Check pH of pond influent and pond contents.
Run total and dissolved sulfides in pond influent.
5. Check pond loading rate (Ib BOD/acre).
t~i c '"weedHT""*'
aq
Corrective
1. Increase detention time in ponds to at least 5ive days
~~~~ by placing ponds in parallel.
2. In the absence of adequate D.O. in the pond, aerate pond
contents or pond influent.
I
'
4. Physically remove floating weeds/£0 increase light
penetration.
79
-------
III. SECONDARY TREATMENT - Final Sedimentation
Problem
Indicators
Monitoring,^
Analysis
and/or
Inspection
SLUDGE OR PIN FLOC FLOWING OVER WEIRS
1. Particulate material rising to surface in clarifier
2. Effluent clarity poor
Corrective
Measures
discharged from clarifier
Attempt to determine height of sludge blanket in
clarifier with depth sampler TIT I rnl uirnfTlm pi>\p
Ktm/s>u^peni*ed sp4J:5Js>el<^^
eck all sludge uptake piping to see that they are
flowing freely nntl
from.Di
6. Check pump rates and schedules of sludge withdrawal
pumps.
'N x-\ ^^
-1-udge
ly at the periphery of th
tank.
8. Determine if the weir overflow rate is equal for
the entire weir.
P
1. Increase pumping rate for greater removal of sludge from
clarifier.
2. Wash down or clean all sludge uptake piping.
3. Repair or replace all damaged sludge scraper mechanism.
4. Level the weir.
5. If uneven weir overflow rate is caused from wind,
install a windbreak.
6. Persistence of this problem would indicate a mal-
function in the secondary treatment process.
80
-------
III. SECONDARY TREATMENT - Final Sedimentation
Problem
ERRATIC OPERATION OF SCRAPER MECHANISM
Indicators 1. Frequent torque switch activated alarms on concentric
driven clarifier equipment
2. Visible slippage or "stuttering" of clarifier sludge
collection mechanisms
Monitoring,
Analysis
and/or
Inspection
1. Check all drives for gear wear.
2. Dewater tanks and check for true travel of scrapper
mechanism.
Corrective
.Measures
1. Repair all worn sludge collector equipment and drives.
81
-------
IV. ADVANCED TREATMENT - Chemical Coagulation and Flocculation
Problem
CHEMICAL COAGULANTS UTILIZED FOR SETTLING OR
DEWATERING SLUDGES THROUGH RECYCLING CAUSE FLOATING
SLUDGES IN PRIMARY SEDIMENTATION TANKS.
Indicators
2.
3.
Floating and gaseous sludge floating in primary
sedimentation tanks during periods of chemical treatment
Poor settling characteristics in the sludge
Poor sludge dewatering characteristics.
Monitoring,
Analysis
and/or
Inspection
Determine types and amounts of chemicals used.
Check the dosing sequence, the rapid mix energy, and
flocculation energy.
Corrective
Measures
Correct the dosage of coagulants and alkalinity in line
with process requirements on the basis of phosphorus
content and a coagulant metal/phosphorus ratio of about
2/1. Institute a regular phosphorus determination and
product turbidity control.
Correct coagulant concentrations and dose points to
favor efficient chemical usage.
Make sure that sufficient rapid mix energy (800-1000 G)
is applied for 1/2 to 2 minutes after dosage to mix
substrate and coagulant. Follow with lower energy
flocculation to agglomerate fines.
Adjust coagulant dosage in line with flow and concentra-
tion variations in the plant inflow. Monitor the treated
overflow turbidity by the hour.
82
-------
DUB
IV. ADVANCED TREATMENT - Ammonia Stripping
Problem
FREEZING IN AMMONIA STRIPPING TOWER
Indicators 1. Ice formation on outside face of tower
2. Drop in ammonia removal efficiency
Monitoring,
Analysis
and/or
Inspection
1. Monitor ammonia removal
2. Check out water temperature for maximum and minimum
values.
3. Check air circulation rate and distribution.
Corrective 1. Use large flow distribution orifices at the outside face
Measures of the tower thus concentrating a curtain of warm water
where the cold air first enters the tower.
2. Reverse draft fan to blow warm inside air outward to
melt the ice.
3. If ammonia removal efficiency drops below 30%, take the
tower out of operation.
83
-------
IV. ADVANCED TREATMENT - Ammonia Stripping
Problem
FORMATION OF CALCIUM CARBONATE SCALE ON AMMONIA STRIPPING
TOWER FILL AND STRUCTURAL MEMBERS
Indicators
1. Visible scale deposits in tower
Monitoring,
Analysis
and/or
Inspection
1. Check pH of tower influent (ph has to be 10.5
or greater.
Corrective
Measures
1. Hose off scale with water jet at periodic intervals.
2. Install water sprays in tower for jetting off scale
at frequent intervals.
3. Clean tower with light solution of sulfuric acid.
84
-------
IV. ADVANCED TREATMENT - Filters
Problem
FILTER BACKWASH WASH WATER HYDRAULICALLY OVERLOADS AND
UPSETS CLARIFIERS
Indicators 1. Surging of clarifier during filter backwash operation
2. Higher turbidity in the treated flow
Monitoring,
Analysis
and/or
Inspection
1. Determine amount and rate of filter backwash water
being recycled to clarifiers.
2. Increase drum speed, backwash pressure or temperature,
and backwash rate.
Corrective 1. Collect backwash wastes in a storage tank and recycle
Measures at a controlled rate to clarifiers.
85
-------
IV. ADVANCED TREATMENT - Microscreen
Problem
FOULING OF FABRIC WITH GREASE AND SOLIDS
Indicators 1. Loss of microscreen efficiency
2. Visible solids and grease on fabric
Monitoring,
Analysis
and/or
Inspection
1. Run suspended solids test on influent to screen.
2. Check for upset in activated sludge process, if any.
Corrective
Measures
1. Increase speed of drum.
2. Increase backwashing pressure.
3. Adjust backwashing cycles.
4. Backwash with hot water. (
5. Backwash with an approved degreasing agent.
86
-------
IV. ADVANCED TREATMENT - Microscreen
Problem
MICROSCREEN EFFLUENT EXHIBITS HIGHER SUSPENDED SOLIDS
CONTENT THAN INFLUENT.
Indicators 1. Increased suspended solids and turbidity on discharge
side of screens.
Monitoring,
Analysis
and/or
Inspection
1. Determine colloidal solids in the influent to
microscreens.
2. Determine total solids removal efficiency of
microscreens.
3. Determine C.O.D. removal efficiency of microscreen.
Corrective 1. Convert colloids in microscreen influent to suspended
Measuressolids by adjusting the pH accordingly or by the addition
of coagulants.
87
-------
IV. ADVANCED TREATMENT - Activated Carbon
Problem
MECHANICAL FOULING OF COLUMNS
Indicators 1. The flashing of aciCumulated /Jlids from ^rbon columns
is followed by ajy abrupt increase in th^ rate of
absorption ' / /
2. Pressure rises in downflow columns
3. Decrease in flow rate.
Monitoring,
Analysis
and/or
Inspection
Corrective
Measures
Run suspended solids and total organic carbon of
column influent and effluent.
3
1.
2.
3.
Check columi operating routine and backwash records.
Bypass column ^ifluent with large amounts of suspended
matter.
Flush columns frequently.
Consider upflow operation, filtration, or larger
carbon grain size.
88
-------
Monitoring,
Analysis
and/or
Inspection
V. DISINFECTION - Chlorination
INSUFFICIENT CHLORINE GAS PRESSURE AT THE CHLORINATOR
ITH ALL CYLINDERS CONNECTED TO GAS PHASE
Chlorine pressure gage at chlorinator is reading too low.
Chlorine supply lines from cylinders are either very
cold or are icing.
ne cylinders or cylinder show a frost line.
o about one-tenth the
Reduce feed rate on chlorinator
rotameter capacity.
'/*
hlorine gas pressure risesmJ^
that the rate of feed ft/^
ded
If after a short period the
appreciably it can be cone
through the chlorinator \f greater than the evaporation
rate of the chlorine cyynders or cylinder at the
prevailing ambient temperature.
Corrective 1. Connect enough cylinders to the supply system so that
Measures the chlorine feed rate does not exceed the withdrawal
rate of the cylinders. For 150 Ib. cylinders the
withdrawal rate at room temperature is 40 Ibs. per day
per cylinder; for ton containers it is 400 Ibs. per day.
At lower temperature it is less.
2. If insufficient cylinder capacity exists, do not try to
apply heat directly to the cylinders, and do not heat
the chlorine storage room with a space heater unless the
control equipment (chlorinator) room can be brought to
the same temperature.
3. The chlorine cylinder should always be kept cooler than
the control equipment if possible; otherwise
reliquefaction of chlorine may occur at the chlorinator.
89
-------
V. DISINFECTION - Chlorination
Problem
INSUFFICIENT CHLORINE GAS PRESSURE AT THE CHLORINATOR
Indicators 1. Chlorine pressure gage at chlorinator is reading too low.
2. Chlorine supply lines from cylinders are either very cold
or are icing.
3. There is icing or considerable cooling at one point in
the chlorine header system between the cylinders and
chlorinator.
Monitoring,
Analysis
and/or
Inspection
Reduce feed rate on chlorinator to about one-tenth the
rotameter capacity.
If icing condition or cooling effect does not disappear,
mark the point wh\ere cooling begins and secure the chlorine
supply system at vhe cylinders, but let the chlorinator
continue to operate\
Corrective
Measures
When chlorine gas pressure at chlorinator reaches zero
and with chlorinator still operating, disconnect flexible
connection to one chlorine cylinder. (This will allow
chlorinator to evacuate residual chlorine in header
system by replacing chlorine with air.)
Disassemble chlorine header system at point where cooling
began. A stoppage or a flow restriction will be found
at or near this point.
After the stoppage has been found it can be cleaned with
a solvent such as tri-chlorethylene.
For massive build-up in black steel pipe header systems,
the pickling process should be used. This consists of
isolating the header system by disconnecting it from the
cylinders at one end, the chlorinators at the other, and
flushing with cold water until the water coming out is
clear. The header then has to be dried with steam or
hot air and final air drying to a dew point of -40 F.
90
-------
V. DISINFECTION - Chlorination
Problem
THERE IS NO CHLORINE GAS PRESSURE AT THE CHLORINATOR,
WHEN APPARENTLY FULL CHLORINE CYLINDERS ARE CONNECTED
TO THE CHLORINE SUPPLY SYSTEM.
Indicators
Chlorinator gas pressure gage is at zero, inlet valve is
open, all valves beginning with chlorine cylinder valve
to the chlorinator are open.
Monitoring,
Analysis
and/or
Inspection
Check the external chlorine pressure reducing valve
installed just downstream of the chlorine cylinders.
Corrective 1. If normal chlorine pressure appears at the chlorinator
Measuressecure all the main chlorine cylinder valves, and start
ventilating fans if available and arrange for maximum
ventilation.
2. Put on a gas mask and gingerly break one flexible
connection joint to release the gas in the header system.
3. Place a bottle of ammonia on the floor near the
connection to be broken and when a white vapor appears
leave the area as fast as possible and return only when
the vapor disappears.
4. Repair the reducing valve which is probably plugged from
the inherent impurities in chlorine gas. These units
should be put on bi-annual overhaul.
5. Install a chlorine gas pressure gage upstream of the
pressure reducing valve.
91
-------
\Indicators.
V. DISINFECTION - Chlorination
IMPOSSIBLE TO OPERATE CHLORINATOR BECAUSE ROTAMETER TUBE
ICES OVER AND FEED RATE INDICATOR IS EXTREMELY ERRATIC.
CHLORINE SUPPLY IS FROM TON CONTAINERS CONNECTED TO
THE GAS PHASE.
Monitoring,
Analysis
and/or
Inspection
Corrective-
Measures
There is sufficient chlorine gas pressure and injector
vacuum and the chlorine is at room' temperature but the
rotameter tube that indicates chlorine feed rate is
nearly completely iced over.
The entire chlorine supply line back to the cylinder is
also iced over, but cylinders are at about ambient
temperature.
Inspect the chlorine cylinder area to see if they are
connected properly. (This problem is specific to. ton
containers.) tv
Shut off main outlet valve on all cylindersAand evacuate
chlorine in header system until gage pressure at
chlorinator reads zero.
Disconnect the cylinder that had ,. ,, _ , , ,
connection to the outlet valve and^rotate it 180 Jand
^reconnect to ,toji_QiLLlet valve and witn j'otner cylinders
closed7place this one in operation.
Tag cylinder so that packager can identify it as
defective with possible broken dip tube but allow
cylinder to remain in1 use until empty..
-------
V. DISINFECTION - Chlorination
Problem
CHLORINATOR WILL NOT FEED ANY CHLORINE EVEN THOUGH
ALL SYSTEMS APPEAR NORMAL.
Indicators
Chlorinator feed rate indicator shows little or no
indication of chlorine flow when chlorine control valve
is moved from closed to wide open position.
The chlorine pressure gage in the chlorinator is normal
but the injector vacuum gage shows an abnormally high
vacuum.
Monitoring,
Analysis
and/or
Inspection
Check for an obstruction in the chlorine gas line near or
at the inlet cartridge of the chlorine pressure reducing
valve inside the chlorinator by shutting off chlorine
supply system at chlorinator; chlorine pressure gage
remains the same or moves downward in pressure at a very
slow rate, i.e., one division per five minutes.
Corrective
Measures
Shut off chlorine supply at the cylinders and try to let
the chlorinator drain off all the chlorine gas pressure
in the chlorine supply line.
If this cannot be done, turn on the ventilating equipment
in the chlorine container space, if any, open all windows,
don a gas mask and break a connection in the chlorine
supply header but be absolutely sure that all chlorine
cylinders have been secured.
When the gas has sufficiently cleared itself from the
working area, disassemble the chlorinator chlorine
pressure reducing valve to remove inlet cartridge and
clean stem and seat with a soft cloth.
If this situation occurs regularly during hot weather,
the source of the trouble usually is a result of the
chlorine cylinders being hotter than the chlorine control
apparatus.
Inspect cylinder area to see if anything can be done to
make the area cooler.
Do not connect a new cylinder if it has been allowed to
sit in the sun.
Install an external chlorine pressure reducing valve
adjacent to the last chlorine cylinder connected to the
supply system.
Precede the reducing valve by a combination chlorine
filter and sediment trap.
93
-------
V. DISINFECTION - Chlorination
Problem
CHLORINE GAS IS LEAKING FROM VENT LINE CONNECTED TO
EXTERNAL CHLORINE PRESSURE REDUCING VALVE (CPRV).
Indicators 1. There is no visible indication of a malfunction.
2. Chlorine escaping from CPRV vent line.
3. Chlorine gas pressure, chlorine feed rate and injector
vacuum are all normal.
Monitoring,
Analysis
and/or
Inspection
1. Confirm leak by placing ammonia bottle near the
termination of the CPRV vent line.
Corrective
The symptom described indicates that the main diaphragm
of the CPRV has been ruptured.
Remove the external CPRV after evacuating header system
and replace with a jumper tube for temporary operation
while valve is being repaired.
Disassemble valve and replace diaphragm.
Inspect the ruptured diaphragm to see if failure is from
corrosion, improper assembly or just fatigue from length
of service.
Consult manufacturer for expert opinion.
If failure is from corrosion the chlorine supply system
should be inspected for moisture intrusion.
94
-------
V. DISINFECTION - Chlorination
Problem
INABILITY TO MAINTAIN CHLORINE FEED RATE WITHOUT ICING
OF CHLORINE SUPPLY SYSTEM BETWEEN EXTERNAL CHLORINE
PRESSURE REDUCING VALVE AND CHLORINATOR. (EQUIPMENT
CONSISTS OF EVAPORATOR, EXTERNAL CPRV AND THE CHLORINATOR.)
Indicators 1. Noticeable cooling of gas line to chlorinator beginning
at outlet of external chlorine pressure reducing valve.
2. Evaporator water bath temperature is normal: 160 to 180°F.
3. Further cooling at point of pressure reduction in
chlorine pressure reducing valve in chlorinator assembly.
4. Deposit of "gunk" on chlorinator feed rate indicator tube
and what appears to be droplets of an amber color liquid.
Monitoring,
Analysis
and/or
Inspection
Reduce feed rate on chlorinator to about 75 percent of
evaporator capacity. If this or further reduction of
feed rate eliminates the above symptoms, the difficulty
is most likely to be insufficient evaporator capacity.
If chlorine gas temperature is available, calculate the
superheat. If there is less than 5°F of superheat, there
is very little reserve capacity in the evaporator. This
is the result of an accumulation of sludge in the bottom
of the liquid chlorine vessel of the evaporator.
Corrective 1. Check for stoppage in the external CPRV cartridge if
Measuressuperheat cannot be measured.
2. Take the evaporator out of the system, flush and clean
it with cold water and dry it in accordance with the
manufacturer's instructions utilizing an "Evaporator
Cleaning Kit." All evaporators should be routinely
cleaned after passage of 250 tons of liquid chlorine.
95
-------
V. DISINFECTION - Chlorination
Problem
CHLORINATION FACILITY CONSISTING OF EVAPORATOR-CHLORINATOR
COMBINATION WITH EXTERNAL CHLORINE PRESSURE REDUCING AND
SHUT-OFF VALVE IS UNABLE TO MAINTAIN WATER-BATH TEMPERATURE
SUFFICIENT TO KEEP EXTERNAL CHLORINE PRESSURE REDUCING
VALVE IN OPEN POSITION.
Indicators 1. External chlorine pressure reducing valve shuts off
intermittently until water bath temperature is raised
above 150°F.
2. Intermittent operation of chlorination equipment
3. Insufficient heat being supplied to evaporator water bath.
Monitoring,
Analysis
and/or
Inspection
1. Check evaporator water bath temperature.
Corrective
After evaporator has been in operation sufficiently long
enough to bring heating elements to operating temperature,
shut down power supply and remove and replace heating
elements.
96
-------
V. DISINFECTION - Chlorination
Problem
INABILITY TO OBTAIN MAXIMUM FEED RATE FROM CHLORINATOR
OR CHLORINATORS WITH ADEQUATE CHLORINE GAS PRESSURE
AT CHLORINATOR
Indicators
Chlorinator is placed into manual control and control
valve is opened wide but chlorine feed rate will not go
beyond 70 to 80 percent of maximum.
Check injector vacuum gage to see if reading is less
than minimum recommended by manufacturer.
Check for injector vacuum reading below ten inches Hg.
Monitoring,
Analysis
and/or
Inspection
1. Reduce feed rate on chlorinator.
2. If the injector vacuum reading increases then increase
the injector water pressure.
3. Verify whether or not inlet water pressure to the
injector is the same as when the installation was first
installed.
4. Check injector water pump pressure against the
manufacturer's operating data.
Corrective
Measures
Disassemble injector and see that the throat and tailway
are clear and without any abnormal deposition of iron or
manganese, and clean the injector parts by soaking in
nuriatic acid, rinse in fresh water and replace.
97
-------
V. DISINFECTION - Chlorination
Problem
INABILITY TO MAINTAIN ADEQUATE CHLORINE FEED RATE
Indicators
Inspection of chlorinator reveals that chlorinator cannot
feed as much as previously noted even though chlorine
supply pressure is adequate.
Monitoring,
Analysis
and/or
Inspection
If effluent is used check the injector operating water
supply for deterioration in supply pump performance.
Corrective 1. In the case of a centrifugal pump the only solution is
Measuresa complete overhaul.
2. If a turbine pump, close down on the needle valve to
maintain the proper discharge pressure.
3. If the turbine pump has worn sufficiently and it requires
operation with the needle valve in the fully closed
position, the pump should be thoroughly overhauled.
98
-------
V. DISINFECTION - Chlorination
Problem
INABILITY TO OBTAIN MAXIMUM OR PROPER FEED RATE FROM
CHLORINATOR WITH ADEQUATE GAS PRESSURE AT CHLORINATOR
Indicators
With chlorinator in manual control and chlorine control
valve is manipulated to very the feed rate, the change
of feed rate response seems sluggish and chlorinator will
not achieve maximum feed rate.
The injector vacuum reading is borderline, and when feed
rate is reduced the injector vacuum does not increase
appreciably.
Monitoring,
Analysis
and/or
Inspection
1. Check the chlorinator vent system for a small vacuum leak
in the chlorine control apparatus by disconnecting the
vent line at the chlorinator and while observing the
chlorinator operation (feed rate and injector vacuum),
place a hand over the vent connection to the vacuum
relief device on the chlorinator. If this action
produces more injector vacuum and more chlorine feed
rate, it signifies that air is entering the chlorinator
via this mechanism (vacuum relief device) because the
springs have become weak due to normal metal fatigue.
2. Moisten all joints subject to a vacuum with ammonia
solution or put paper impregnated with orthotolidine at
each of these joints. With chlorinator operating at
maximum feed rate, close the injector discharge line as
rapidly as possible. If there is a vacuum leak in the
chlorinator system it will be detected by either the
ammonia or the paper.
Corrective 1. If the vacuum leak is in the vacuum relief device,
Measuresdisassemble the mechanism and replace all the springs.
2. Repair all other vacuum leaks by tightening a joint,
replacing gaskets, replace tubing and/or compression nuts.
99
-------
V. DISINFECTION - Chlorination
Problem
EXCESSIVE CHLORINE ODOR AT POINT OF APPLICATION-
Indicators 1. Air cover above area of chlorine diffuser reacts with
ammonia solution to produce typical white wisps of
"smoke" indicating escaping molecular chlorine.
Monitoring,
Analysis
and/or
Inspection
1. Scattering ammonia indicator solution onto the wastewater
stream over the area of the diffuser produces white fumes
at the surface.
2. Check chlorine solution strength.
Corrective 1. Add enough injector water to bring the chlorine solution
Measuresstrength down to 3500 ppm chlorine at maximum expected
:chlorine feed rate.
2. If the chlorine diffuser is situated below the injector
which leads to a negative head in the solution line,
install a special diaphragm protected chlorine solution
pressure gage in the highest point of the chlorine
solution discharge line and regulate the injector water
flow so that there is a 2 to 3 psi positive pressure at
this point.
100
-------
V. DISINFECTION - Chlorination
Problem
CHLORINATOR WILL NOT FEED ENOUGH CHLORINE TO PRODUCE
A PROPER CHLORINE RESIDUAL AT THE SAMPLING POINT.
Indicators
A routine spot check sampling shows that at some hours
of the day there is an adequate residual but there are
times during the day when there is no residual.
If there is a chlorine residual analyzer the chart will
show periods during the day of insufficient chlorine
residual.
Monitoring, 1. Ascertain that if the chlorination equipment is being
Analysisused for disinfection that it is equipped to proportion
and/or the chlorine feed rate in accordance with the flow of
Inspection the wastewater.
2. If it is flow proportional, check to see if the meter
capacity on the chlorinator matches the pl'ant flow
meter capacity.
3. Disconnect the flow proportional control and by manual
control test the chlorinator to see if it will pull
maximum feed rate.
4. Determine if solids have settled to the bottom of the
contact chamber.
Corrective
Measures
The automatic control features of the chlorinator should
be repaired by the manufacturer's field service per-
sonnel- who are equipped to simulate the various types
of electric and pneumat'ic signals commonly used for
chlorinator control.
If neede'd'', clean the chlorine contact chamber.
101
-------
V. DISINFECTION - Chlorination
Problem
WIDE VARIATION IN CHLORINE RESIDUAL IN EFFLUENT AS
DETERMINED BY HOURLY CHLORINE RESIDUAL DETERMINATIONS
Indicators
Inability to adjust dosage so that there is reasonable
agreement of chlorine residual throughout a 24-hour
period as determined by occasional chlorine residual
analysis at each shift.
Monitoring,
Analysis
and/or
Inspection
While in flow proportional operation the feed rate of the
chlorinator should be plotted on a piece of graph paper
against the flow meter reading. The plots of wastewater
flow versus chlorine feed rate should yield a straight
line.
Corrective
Measures
If the feed rate plots do not follow a reasonably
straight line, it is well to recheck the zero and span
of the flow proportional control device on the
chlorinator. First make the zero check and then the span
check in accordance with the manufacturer's instructions.
If this does not correct the difficulty, it may be
necessary to replace operating parts within the
controller to achieve satisfaction.
If after the flow proportional control system on the
chlorinator has been corrected the irregular chlorine
residual reading continues, then it is recommended that
a continuous chlorine residual analyzer be installed.
102
-------
V. DISINFECTION - Chlorination
Problem
CHLORINE RESIDUAL ANALYZER RECORDER CONTROLLER DOES
NOT APPEAR TO CONTROL THE CHLORINE RESIDUAL PROPERLY.
Indicators 1. Recorder draws a poor line on the chart that seems not
to bear any relation to the "set point."
Monitoring,
Analysis
and/or
Inspection
1. First check the loop-time in the system. This is best
accomplished by turning off the gas supply to the
chlorinator and determining the length of time required
to show a sharp drop in the residual on the analyzer
chart.
2. Disconnect the analyzer cell output leads from the cell
and apply a simulated signal to the recorder mechanism
from a manually controlled external signal generator.
(Authorized chlorinator repair personnel carry such a
device as part of their tool kits.)
3. Check buffer additive system to see if pH of sample
going through the cell is maintained at 5 or less.
4. Check electrode bombardment system and see that
electrodes are clean, particularly the noble metal
electrode (Pt. or Au.). Do not disturb the copper
electrode unless it is fouled with grease.
5. If residual analyzer is being used to measure total
residual, check to see if sufficient potassium iodide
is being added for the amount of residual being measured.
6. Reconnect cell output leads and make a zero, span and
temperature check by following the manufacturer's
procedure for a routine calibration.
103
-------
Corrective 1. If the loop time is found to be in excess of 5 minutes,
Measures satisfactory operation will not be achieved until the
loop time is brought down to 5 minutes or less. This
can be accomplished by moving the injector closer to the
point of application, increasing the velocity in the
sample line to the analyzer cell, by moving the cell
closer to the sample point, or by moving the sample point
closer to the point of application.
2. If the line on the chart indicates proper operation when
subjected to a simulated signal, this signifies that the
equipment between the cell and the readout of the pen is
satisfactory. The erratic or poor line can either be
caused by poor mixing of chlorine at the point of
application or faulty operation of the cell. Poor mixing
can be verified by setting the chlorine feed rate for a
constant dosage (proportional to flow) and analyzing a
great many grab samples over a ten minute period as
quickly as possible. A poor mix will show rapid wide
swings of the recorder pen. Consider mixing the point
of application and/or install some type of mixing device
to cause turbulence at the point of application.
3. If poor mixing is not the cause, and if the electrodes
are clean, and if the pH and KI additive system is normal,
then the difficulty must be in the cell and it should be
replaced.
4. If when the simulated signal is applied to the recorder
mechanism and the recording system does not respond
properly, the difficulty lies in the electrical
components of the recorder mechanism. Authorized service
personnel should be summoned to correct the difficulty.
104
-------
V. DISINFECTION - Chlorination
Problem
CHLORINATION SYSTEM CONSISTS OF EITHER COMPOUND-LOOP
CONTROL OR DIRECT RESIDUAL CONTROL AND SYSTEM DOES
NOT APPEAR TO BE CONTROLLING PROPERLY.
Indicators
Chlorine residual line on analyzer chart appears normal
but does not track close enough to set point.
Monitoring,
Analysis
and/or
Inspection
If the chlorine residual analyzer is operating properly,
check the chlorinator system to see that it is functioning
properly over its entire range of feed rate. Check to
see if the chlorination system is feeding enough chlorine
to satisfy the maximum demand; also check to see if the
rotameter tube range is sized so that incremental
corrections in feed rate by the residual controller are
not too large. These two factors would cause wide swings
in the chart line, or not allow the chlorine applied to
ever actually "catch up" with the set point.
Corrective
Measures
If the chlorination system will not feed enough chlorine,
consult the corrective measures described previously
under the problem of chlorination control equipment
unable to feed enough chlorine.
If the chlorinator rotameter tube range gives too large
or too small an incremental change, replace with a proper
range of feed rate.
105
-------
V. DISINFECTION - Chlorination
Problem COLIFORM COUNT DOES NOT MEET THE REQUIRED DISINFECTION
STANDARDS SET BY REGULATORY AGENCIES.
Indicators 1.
Routine analysis of effluent or receiving waters shows
MPN coliform organism to be in excess of that required
by regulatory authorities.
Monitoring, 1. Check capacity of chlorination equipment as follows: For
Analysis primary effluent chlorinator capacity should be from 175
and/or to 200 Ib per MG. For secondary effluent 100 to 125 Ib
Inspection per MG and for tertiary effluent 75 to 100 Ib per MG
unless nitrogen removal is required. For the latter or
for those plants requiring free residual chlorine,
equipment capacity must be 10 mg/1 of chlorine for each
mg/1 ammonia nitrogen in the effluent.
2. All chlorination equipment used for disinfection of waste-
water effluent should have at the very least control propor-
tional to the effluent flow. The capacity of the chlorina-
tor should also be based on the maximum reading of the flow
meter.
3. Continuously record the residual in the effluent with an
amperometric type chlorine residual analyzer.
N
4. Check for short circuiting in contact chamber.
Corrective 1. Chlorination equipment should be brought up to optimum capac-
Measures ity requirements. The necessary equipment should be installed
to provide flow proportional control. In plants where only
an influent meter exists, it may be required to install an
effluent meter. After the proper primary meter is installed
then the chlorinator can be modified by adding a chlorine ori-
fice positioner to be operated either ( electrically or pneu-
matically from the primary meter.
2. A chlorine residual analyzer should be installed to properly
monitor the chlorine control system. Using this apparatus to
automatically control the chlorine dosage is optional; how-
ever, experience shows that the change in chlorine demand of
most domestic wastewaters is significant enough to warrant
the small added expense to accomplish automatic dosage control.
3. Install additional baffling in contact chamber.
4. If needed, install a mixing device in contact chamber.
106
-------
V. DISINFECTION - Chlorination
Problem COLIFORM COUNT DOES NOT MEET THE REQUIRED STANDARDS
FOR DISINFECTION.
Indicators
Monitoring,
Analysis
and/or
Inspection
Corrective
Measures
1. Routine analysis of effluent or receiving waters shows
MPN of coliform organisms to be in excess of the
required standards.
1. Check to see if chlorine capacity is adequate, control
system is functioning properly and effluent is being
. monitored with a continuous chlorine residual analyzer.
2. Check the chlorine contact time at low flow, average flow
and maximum flow to determine the optimum residence time
of the process. With this as a basis analyze five
replicate samples for each hour around the clock on
Monday, Wednesday^ Friday and Sunday for coliform MPN
after the following treatment: samples are to be taken
from the effluent prior to point of application of
chlorine and dosed in the laboratory with the same amount
of chlorine as that applied by the Chlorination equipment.
The chlorine for this procedure should be taken from the
plant chlorine solution line, standardized according to
Standard Methods and added to one liter replicate sample
of effluent. Upon addition the chlorine solution should
be rapidly and thoroughly mixed, then allowed to stand
for the amount of time determined previously at the
optimum residence time. At the expiration of the
residence time one portion of the samples should then be
analyzed for chlorine residual using the iodometric back
titration procedure while another portion should be
dechlorinated and analyzed for coliform MPN in accordance
with Standard Methods.
3. If the resulting coliform MPN from the above analysis is
satisfactory, it is then reasonable to assume that the
mixing at the point of application is at fault , because
stirring chlorine in a batch process described above
results in ideal chemical mixing.
4. Check for solids buildup in contact chamber.
1. If the difficulty is too low a residual raise feed rate
and increase contact time if possible.
2. If poor mixing is the problem install a mixing device of
high turbulence such as exists in an hydraulic jump or a
combination of turbulent flow and mechanical mixer.
3. Clean contact chamber to reduce solids buildup.
107
-------
V. DISINFECTION - Chlorination
Problem PLANT EFFLUENT DOES NOT MEET TOXICITY REQUIREMENTS
BECAUSE CHLORINE RESIDUAL TO ACHIEVE PROPER
DISINFECTION IS AT TOO HIGH A LEVEL.
Indicators 1. Toxicity level is too high as determined by present
bio-assay procedures.
Monitoring, 1. Chlorine residual as determined by iodometric method
Analysis using back titration method is deemed toxic to fish and
and/or other aquatic life in the receiving waters.
Inspection
Corrective 1. Install a dechlorination facility to operate in
Measures conjunction with the Chlorination system.
108
-------
Problem
Indicators
Monitoring,
Analysis
and/or
Inspection
VI. METERING
PLANT. METER UNRELIABLE
A. .
Drop or sharp increase in totalized .dry weather
If meter operates on a float, check float well
obstructions.
If meter operates on bubbler, check bubbler tube for
damage. Also check air pressure gage to see that meter
is getting proper air flow.
Bypass measuring weir or f
to see if meter Zespos..
Check height lof flow over weir or in/ flume at dlfd
time intervals and, using the weir or flume characteristics
formulas calculate flow and compare with flow meter data.
Compare water surface elevation immediately behind weir
or flume with elevation of water in float or bubbler well.
Ascertain the fact that none of the plant's process
return flows (centrate, supernant, waste activated
sludge, etc.) are discharged upstream from the meter.
Install a portable flow meter in the weir or flume and
compare results with
If metered flow discltarges/iinto a wet well or other
chamber which has.,* known volume and outflow can be shut
off, record time' of measured rise in chamber and
calculate infl<6w rate. Compare calculated data with
109
-------
If wastewater treated at the plant is supplied by one or
more utilities and the total amount of water used is
metered, compare area water consumption with plant flow.
During fall or early winter months, water consumed is
approximately 10% more than wastewater discharged.
10. Check magnetic *Aow meter cores for grease bui.M-uB.Q
estrictions. . .
Corrective 1. Keep all floats and bubbler wells clean and free of
Measures grease by periodic maintenance.
2. Differences between inside and outside or bubbler well
water surface elevations are due to extreme velocities
in the immediate area of these wells. If possible, move
wells to a more quiescent area behind the weir or flume.
3. Clean all foreign matter off weir plates.
4. If problem appears to be in the meter, recording or
telemetering equipment, a qualified technician should be
called in to repair and calibrate the metering equipment.
110
-------
VII. SOLIDS HANDLING - Sludge Thickeners
Problem
ODOR FROM THICKENER
Indicators
Monitoring,
Analysis
and/or
Inspection
1. Odors of hydrogen sulfide origin
2. Floating or gaseous sludge in thickener
3. Corrosion of thickener concrete structure and metal work
1.
2.
3.
4.
Run/Total and
ffluent.
^solved
test of thickener
Check pumping rate and frequency of pumping raw sludge
from thickener.
Run total solids test on raw sludge pumped.
Dewater thickener and check operation of a scrapper
and/or stirrer arms and sludge removal equipment.
5. Determine sludge blanket depth.
Corrective
Measures
1. Adjust pumping rate to remove solids at a frequent rate
and at not less than 3% total solids.
2. Repair or replace all damaged sludge collector
mechanisms.
3. Cover thickener and exhaust gases to an odor control
scrubber.
Ill
-------
VII. SOLIDS HANDLING - Sludge Thickeners
Problem
Indicators
Monitoring,
Analysis
and/or
Inspection
THICKENER CONTENTS DO NOT SETTLE
1. Floating sludge on thic
2. Floe in thickener effluent
\^/Xlny3^reased^\oadi*lgs~^n P/"Vnar y^sedinrenVarciW^fanics and
secoh43«ry treatment p**°cess*/ \s
4.. Excessive sludge solids in the overflow
5. Poor concentration of underflow.
Run tota1J'ssolids on thickener effluent.
Run total solids in raw sludge withdrawn from thickener.
Run total solids of all thickener inflows and compare
to thickener design capacity.
Run 30 minute settleability test of waste activated
sludge inflow to thickener.
Corrective
Measures
If thickener effluent contains high solids and the raw
sludge withdrawn low solids, dose thickener with polymers
or other coagulants.
If solids loading exceeds thickener design capacity,
partially bypass thickener, if possible, by pumping raw
sludge from the primary sedimentation tanks directly to
the point of disposal, digester, or incinerator.
If waste activated sludge pumped to thickener does not
^readily settle, re-aerate or treat with coagulants.
112
-------
VII. SOLIDS HANDLING - Sludge Thickeners
Problem
SLUDGE PUMPED FROM THICKENER HAS LOW SOLIDS CONCENTRATION
Indicators
1. Thin or watery sludge discharged to point of disposal
Monitoring,
Analysis
and/or
Inspection
1. Run total solids of raw sludge pumped from thickener.
2. Check pumping cycle and rate of pumping raw sludge
from thickener.
3. Check rate of inflow to thickener.
4. Run total solids of thickener inflow.
5. Determine depth of the sludge blanket.
Corrective 1. Adjust pumping rates and cycles, preferably with
Measures timers, and remove raw sludge from thickener at a density
not less than 3% total solids.
2. Adjust thickener inflows to apply total solids to
thickener of not less than 2%.
3. In gravity thickness adjust pumping cycles to
maintain 3 to 4 ft sludge blanket.
113
-------
VII. SOLIDS HANDLING - Sludge Digestion (Anaerob
Problem
Indicators
SCUM BLANKET IN TANK
Monitoring ,
Analysis
and/or
Inspection
. 1.
2.
3.
4.
1. Decrease in dige'ster gas production
2. Crust visible through sight glasses in digester roof g *
3. Unable to supernate from upper level of digester
Core blanket through digester thief holes to
thickness.
Check digester temperature.
Check daily digester gas production.
Determine gallons of scum pumped to digester daily.
Corrective
Measures
If possible, recirculate digested sludge from bottom of
digester to top of scum blanket.
If digester has a gas mixing system, run system
continuously while increasing digester temperature to
not more than 105°F with the incremental increases not
exceeding 1°F per day.
If digester has mechanical mixers with draft tubes ,
degassify digester, break up scum with a high pressure
water jet and direct to draft tubes.
Clean digester and find alternate means of scum disposal.
If digester has gas mixer system, place temporary gas
diffusers in thief holies and pipe compressed digester
gas /to them.
114
-------
VII.
LIDS HANDLING,- Sludge Digestion (Anaerobic)
DIGESTERGAS PRODUCTION
Indicators
Monitoring,
Analysis
and/or
Inspection
Corrective
Measures
2.
3.
4.
2.
3.
4.
5.
6.
7.
8.
Gas produced hafe sen^fic
Gas producedyrfoes ifot ignite^
Increase in^ligearcer volatile acids
Increase ±y vol^ile acid/alkalinity
Determing digester volatile acid, alkalinity, and pH
of digested sludge together with trend of volatile
acid/alkalinity ratio.
Check gas meter and piping for restrictions.
Monitor volume of raw sludge pumped to digester daily.
Determine total solids, volatile solids, and pH of raw
sludge pumped to digester.
Check digester temperature.
Sound digester to determine depth of scum blanket and
grit residue on bottom.
Calculate volatile matter reduction in digester.
Check for toxic material i
digeste
If volatile acjra to alkalinity
0.2 and pH billow 6.5 add/lime
volatile a/ld/alkalin/i r
Do not fe^a digestejr raw
than 7.
If volatil
decrease,
Do not
solids
disconti
greater than
decrease
pH.
ranges (less
50%
pH rises
eefci djAest'ej5xrawvSi3jJ4ge— with average volatile
l3S'
x
an-^75%.
If possible transfer digested sludge with a volatile
acid/alkalinity ratio of 0.2 from another digester to
affected digester.
If scum blanket and/or grit deposits comprise more than
50% of the effective volume of the digester, clean the (
tank. * iJf^ijjJti AAMW^A
Keep digester temperature at 98 F. (vflM/TUA** r*'v'rw I
r o r •
Clean all restrictions in gas lines and/or meters. v_
If toxic material has killed digester, clean digester
and determine source of toxicity to prevent recurrence.
-------
VII. SOLIDS HANDLING - Sludge Digestion (Anaerobic)
INCREASE IN VOLATILE ACID/ALKALINITY RATIO IN DIGESTER
Indicators 1. Drop i/i digestenrgas production
2. Hydr/gen sulfd^fle odoijr from digegrter superna
Monitoring,
Analysis
and/or
Inspection
Corrective
Measures
1.
2.
3.
4.
1.
2.
3.
4.
5.
6.
7.
Determine volatile acid, alkalinity and pH
sludge at least twice daily.
Check digester temperature.
Check pH of raw sludge pumped^to cfigester.
Check mixing in digester.
If digester pH is below 6.5, add lime to digester
If volatile acid/alkalinity ratio is greater than 0.4
decrease or discontinue feeding digester and add lime.
Do not feed digester raw sludges with pHs lower than 6.8.
Do not let digester temperatures drop below 90°F.
If possible, transfer sludge with low volatile acid/
alkalinity ratio content from another digester to
affected digester.
Keep contents of digester well mixed.
Decrease sludge withdrawal rates from digester.
116
-------
VII. SOLIDS HANDLING - Sludge Digestion (Anaerobic)
Problem
FOAM IN DIGESTER
Indicators 1. Foam discharged from upper level supernatant lines
2. Froth visible through sight glasses in digester roof
Monitoring,
Analysis
and/or
Inspection
1. Determine total and volatile solids of sludge being
pumped to digester and volume pumped.
2. Determine pH of digester contents.
3. Check digester temperature daily.
4. Monitor withdrawal rate of sludge from digester.
5. Ascertain depth and/or thicknesses of grit deposits
and/or scum layers.
6. Check digester mixing program and effectiveness of
mixing equipment.
Corrective 1. Maintain digester pH between 6.8 and 7.2 and volatile
Measures acid/alkalinity ratio below 0.2 by adding lime.
2. Reduce or discontinue pumping raw sludge to digester.
3. Maintain digester temperature constant and at least
at 95°F.
4. Attempt to thoroughly mix digester by recirculation or
by available digester mixing equipment.
5. Break up scum layers or, if not possible, clean digester.
6. If possible, add digested sludge from a healthy digester.
117
-------
VII. SOLIDS HANDLING - Sludge Digestion (Anaerobic)
Problem
LOW REDUCTION OF VOLATILE SOLIDS IN DIGESTER
Indicators
1. Volatile reduction calculates to less than 50%
Monitoring ,
Analysis
and/or
Inspection
1
3
4
5
Determine total solids of digested sludge and/or raw
sludge being pumped to digester.
Monitor solids loading to digester daily.
Monitor solids withdrawal from digester.
Check total solids in digester supernatant.
Ascertain depths and/or thickness of grit deposits
and/or scum layers.
6. Determine volatile acid/alkalinity ratio and pH of
digested sludge.
7. Monitor digester gas production.
Corrective
Measures
2.
3.
4.
5.
If total or volatile solids daily loading of digester
exceeds design loading, reduce the amount of sludge
pumped to the digester daily.
Keep digester temperature above 95°F.
Raw sludge pumped to digester should contain more than
50% volatile solids.
Recirculate and mix digester.
Prolong periods of withdrawing digested sludge until
volatile reduction is above 50%.
Lower volatile acid/alkalinity ratio and raise pH above
6.5 by adding lime to digester.
If supernatant contains high solids content, let
digester settle.
118
-------
VII. SOLIDS HANDLING - Sludge Digestion (Anaerobic)
Problem
HIGH PERCENT SOLIDS IN DIGESTER SUPERNATANT
Indicators .1. Supernatant very dark and thick
2. If supernatant is circulated to plant headworks, primary
and/or secondary treatment processes efficiency drops
severely.
Monitoring,
Analysis
and/or
Inspection
1. Determine total solids of digester supernatant while
supernating from different levels in the digester.
2. Determine total solids of digested sludge.
3. Monitor amount of raw sludge, activated sludge, and scum
pumped to the digester daily.
4. Check pH of digester supernatant.
5. Determine length of time of digester mixing.
Corrective 1. If supernatant contains more than 1% solids, do not mix
Measures digester and feed alternate digester if possible.
2. Supernate from digester level which gives the least
solids in the supernatant.
3. Supernate from one digester into another if possible.
119
-------
VII. SOLIDS HANDLING - Centrifuging
Problem
LOW SOLIDS RECOVERING RATE
Indicators 1. Centrifuge efficiency falls below 60%
2. Solids in centrate exceed 3%.
3. Centrate very dark in color.
4. If centrate is recirculated to the plant headworks, the
efficiency of primary and secondary treatment processes
are directly affected.
5. Cake appears thick and quite wet.
Monitoring,
Analysis
and/or
Inspection
1. Calculate centrifuge efficiency.
2. Monitor sludge feed rate to centrifuge and percent
solids in sludge.
3. Monitor coagulant, if any, feed rate to centrifuge.
4. Check centrifuge for mechanical wear.
5. Check pool depth.
Corrective
Measures
1. Decrease sludge feed rate to centrifuge.
2. Increase chemical coagulant dosage, if any.
3. Repair or replace all worn centrifuge parts.
4. Increase pool volume and bowl speed.
5. Reduce conveyor speed.
120
-------
VII. SOLIDS HANDLING - Vacuum Filters
Problem
LOW SOLIDS RECOVERY
Indicator 1. High solids in filtrate
2. Poor clarity filtrate
Monitoring,
Analysis
and/or
Inspection
1. Calculate filter efficiency.
2. Monitor coagulant, if any, feed.
3. Check filter mesh for blindings or coarseness.
Corrective
Measures
1. Increase chemical coagulant feed rate.
2. Clean filter media.
3. Install fine mesh filter media.
4. Check sludge washing (elutriation) process.
5. Check filter drum speed and operation cycle.
6. Change types of coagulants being used.
121
-------
VII. SOLIDS HANDLING - Incineration
Problem
ABNORMALLY HIGH TEMPERATURE IN FURNACE
Indicators
Temperature indicator exceeds limit of maximum operating
temperature.
High temperature alarm activated.
Monitoring,
Analysis
and/or
Inspection
1. Check rate of fuel consumption to determine if excessive.
2. Check to determine if fuel feed is off and temperature
is still rising. Greasy solids may be present.
3. Check temperature indicator to see if it reads all the
way up on the scale.
Corrective
Measures
Decrease fuel feed rate, if excessive, in relation to
sludge feed rate.
If temperature rises without supplementary fuel feed,
greasy solids may be present in sludge. (This occurs
infrequently when 100% primary sludge is incinerated.)
To lower temperature, raise air feed rate while holding
sludge feed rate constant. If air feed rate is at
maximum, reduce sludge feed rate slightly.
If temperature indicator is all the way up the scale,
this is an indication that the termocouple well is burned
out. Replace thermocouple with spare unit, repair or
replace thermowell with spare.
122
-------
VII. SOLIDS HANDLING - Incineration
Problem
ABNORMALLY LOW TEMPERATURE IN FURNACE
Indicators
1. Temperature indicator shows low on scale.
Monitoring,
Analysis
and/or
Inspection
1. Check calorific value of sludge to determine if it is
decreasing.
2. Check moisture content of sludge to determine if it is
increasing.
3. Determine level of excess oxygen in stack.
Corrective
Measures
If calorific value of sludge is low, or if sludge moisture
content is high, increase the supplementary fuel feed
rate.
If excess oxygen is abnormally high in stack exhaust,
reduce the air feed rate slightly or increase sludge
feed rate.
123
-------
VII. SOLIDS HANDLING - Incineration
Problem HIGH OXYGEN LEVEL IN FURNACE STACK EXHAUST
Indicators 1. Oxygen analyzer (recorder chart) indicates excessive
oxygen in stack exhaust
Monitoring, 1. Determine total and volatile solids of sludge fed to
Analysis furnace.
and/or
Inspection
2. Check to determine if sludge is being fed to incinerator.
Corrective 1. If sludge being fed to furnace is low in solids, increase
Measures the speed of sludge pump which feeds centrifuge. If the
air feed rate is low and the sludge rate at a maximum
and the exhaust oxygen is still high, shut down. The
sludge supply to the furnace is inadequate.
2. If sludge is not being fed to incinerator, check for
blockage of sludge in feed chute and check sludge feed
pump stator. Unplug chute or repair stator if not in
good condition.
124
-------
VII. SOLIDS HANDLING - Incineration
Problem
LOW OXYGEN LEVEL IN FURNACE STACK EXHAUST
Indicators 1. Oxygen analyzer (recorder chart) indicates low oxygen
in stack exhaust.
Monitoring,
Analysis
and/or
Inspection
1. Check volatile content of sludge fed to furnace to
determine if increasing.
2. Check sludge for grease content to determine if
increasing.
3. Check to determine if air flow to furnace is restricted.
Corrective 1. If the volatile content of the sludge is increasing or
Measures if the grease content of the sludge is increasing,
increase the air feed rate. If the air feed rate is at
maximum decrease sludge feed rate.
2. Remove any restrictions or blockages in air conduits. .
125
-------
VII. SOLIDS HANDLING - Sludge Lagooning
Problem
EXCESSIVE SOLIDS CARRIED OVER FROM LAGOON
SUPERNATANT TO PLANT INFLUENT
Indicators 1. Dark supernatant discharged from sludge lagoons
2. Solids removal efficiency of plant treatment processes
is lowered.
Monitoring,
Analysis
and/or
Inspection
1. Determine total and suspended solids of lagoon
supernatant.
2. Measure depth of sludge in lagoons.
3. Check for broken dikes between lagoons.
4. Check rate and volume of application of digested sludge
to lagoons.
5. Determine total solids of sludge being applied to
lagoons.
Corrective 1. Reduce volume of sludge applied to lagoons thereby
Measures reducing depth of sludge in lagoon.
2. Repair all broken dikes between lagoons.
3. Delay release from lagoons of supernatant with heavy
solids content until sludge is allowed to settle.
126
-------
VII. SOLIDS HANDLING - Sludge Lagooning
Problem
ODORS FROM SLUDGE LAGOONS
Indicators
1. Obnoxious odors from sludge lagoons.
Monitoring,
Analysis
and/or
Inspection
1. Determine volatile acid/alkalinity ratio and pH of
digested sludge being applied to lagoons.
2. Determine total and dissolved sulfide of lagoon
supernatant.
Corrective 1. If volatile acid/alkalinity and pH tests indicate a sour
Measures digester, attempt to correct problem at source.
2. Apply lime to surface of lagoon.
3. Install peripheral odor control system.
4. Flood lagoon with heavy chlorinated water.
127
-------
-------
CLASSIFICATION OF
WASTEWATER
TREATMENT PLANTS
-------
Appendix A
CLASSIFICATION OF WASTEWATER TREATMENT PLANTS
This section of the manual contains information for the classification
and identification of wastewater treatment plants by various designations.
These include:
• Definitions of the classes of plants by function
• Operator classification
• Geographic location and climatic conditions
• Common processes and operational units
Also included is a matrix by which treatment systems are clas-
sified by their unit operations, removal efficiencies and expected
effluent quality.
This section is used by:
• Isolating treatment system (by various classification)
• Determining the units which fall into that general system
• Learning the performance capabilities of the system.
This information, along with operational .data for the particular
system from Section II of this manual, is compared to the performance and
operational data of the plant being evaluated and is to be considered in
the overall evaluation of the plant.
CLASSIFICATION BY FUNCTION
Following are generalized definitions of classes of treatment plants
according to their functions:
1. Primary treatment - Those wastewater treatment plants that employ
methods which remove or reduce a high percentage of the suspended
and floating solids but little or no colloidal and dissolved matter.
2. Secondary treatment- Those methods which remove or reduce fine
suspended colloidal, dissolved solids, and cause the reduction
of organic material by biological oxidation.
3. "Advanced waste treatment - Those methods which remove or reduce
nutrients, residual organics, residual solids and pathogens by,
but not limited to, sand filtration,chemical treatment, carbon
absorption, ammonia stripping, electrodialysis or reverse osmosis.
A-l
-------
OPERATOR CLASSIFICATION
The classification system used in the area of the plant being evaluated
should be reviewed to see if the proper personnel are being utilized for the
existing treatment system.
Table A~l shows the diversification of wastewater treatment plant
classifications as denoted by their type, design flow and population served,
contrasted with the class of operator which should be capable of operating
them. These classifications have been established by the California Water
Pollution Control Association and the California State Water Resources
Board. Evaluators should be aware that most states will have their own
classification system.
Table A-l
OPERATOR AND TREATMENT PLANT CLASSIFICATION
California Water California*
Pollution Control Operator Treatment Process
Association Classifications
Design Flow Population
(MGD) Served
IV
III
II
I
la
I Stabilization Pond
Primary
II Primary
Biofiltration
III Primary
Biofiltration
Activated Sludge
Tertiary
IV- Primary
Biofiltration
Activated Sludge
Tertiary
V Biofiltration
Activated Sludge
Tertiary
All 2000
1 or less
1-5 2000 to
1 or less 10,000
5-20 10,000 to
1-10 40,000
5 or less
1 or less
20 & over 40,000
10-30
5-20
1-10
30 & over
20 & over
10 & over
*Classification adopted by the State Water Resources Control Board
A-2
-------
Temperature zones and their approximate sphere of influence, along with
probable effects on operating efficiencies , are defined below.
1. Cold Zone - average January air temperature of 30 F or less
will cause a decrease from 4 to 5 percent in operating efficiency
2. Temperate Zone - average January air temperature of 35 to 45 F
will cause a decrease of 4 to 5 percent at the 35 F range but
normal operation at the higher temperature
3. Warm Zone - average January air temperature of 50 to 70 F allows
normal operation at the low temperature and a possible 4 to 5
percent increase in efficiency at the higher range.
The following sketch delineates the approximate climate zones in the United
States.
Alaska
Hawai i
LOCATION OF TEMPERATURE ZONES
IN THE UNITED STATES
'A-3
-------
COMMON PROCESSES AND OPERATIONAL UNITS
The purpose of this subsection will be to identify all of the opera-
tional units and processes common to wastewater treatment plants operating
in the primary, secondary and advanced waste treatment mode.
While every treatment plant can be considered unique, it is obvious
that most treatment plants will have many operations and processes in com-
mon. Below is a list of the most common units used in various treatment
modes.
Pretreatment
To remove or reduce floating solids and coarse suspended solids, use:
Racks
Medium screens
Grit chambers
Skimming tanks
Primary Treatment
To remove or reduce fine suspended solids, use:
Fine screens
Sedimentation
a. Plain sedimentation tanks, with or without
mechanical sludge-removal devices
b. Septic tanks (biological action also takes place)
c. Imhoff tanks (biological action also takes place)
d. Chemical precipitation tanks
Secondary Treatment
To remove or reduce suspended colloidal and dissolved solids ,
oxidize with
Filters - intermittent sand filters
contact filters
trickling filters
Aeration - activated sludge
contact aerators (as used in aerated lagoons)
Chlorination
Oxidation ponds
Disinfection
Chlorination
Ozone
Advanced Waste Treatment
Chemical/physical treatment methods
Carbon absorption
Ammonia stripping
Electrodialysis
Reverse osmosis or desalting
Microscreening
A-4
-------
Ultimate Wastewater Disposal
Discharge into receiving waters
Irrigation or disposal on land by
a. Application to surface
b. Subsurface irrigation
c. Groundwater recharge
Treat by advanced treatment system and reuse for
industrial water supply or possibly a fire protec-
tion system
Treatment and Disposal of Wastewater Solids
Screenings
a. Treatment
(1) Medium - shred and digest
(2) Fine - digest
b. Disposal
(1) Medium - burial or incineration
(2) Fine - burial or incineration
Settled Solids (sludges)
a. Treatment
(1) Sludges from primary and secondary
treatment by:
(a) Digestion
(b) Thickening (by gravity or flotation; may or
may not be conditioned by elutriation or
chemicals)
1) Vacuum filtration
2) Drying on beds or in kilns
3) Centrifugation
b. Disposal
(1) Wet sludges - dumping at sea or piping to sea
(where still permitted)
(2) Dried or dewatered sludges - incineration or use
as soil conditioner or deposit in a landfill
A-5
-------
Performance of Treatment Systems
Table A-2 is a classification matrix of treatment systems by their unit
operations, removal efficiencies and expected effluent quality. It indicates
the percentage removal of constituents (based on process effluent to process
influent) and ranges of effluents of treatment systems which are employed
in the wastewater treatment.• Most of the systems shown have some form of
pretreatment, in combination with primary, secondary or advanced, unit
operation which would provide the influent quality that can be handled by
the treatment system. In order for plants to approach the effluent ranges
indicated, each unit operation would have to be examined and evaluated to
determine what operation could be improved without affecting other plant
operations.
A-6
-------
UNIT OPERATIONS
PRIMARY®
illilill
•sssliisl
^—
By Aaaonlm Stripping Tower
SECONDARY
h
*- £ S
1 a 1
| i |
—
•
Physical -Chemical
Sand Filtration >
Carbon Adsorption >
9
Sludge Treatment A. Disposal
•BE—
TREATMENT SYSTEM
PRIMARY TREATMENT
ACTIVATED SLUDGE
. Conventional
. Contact Stabilization
. Completely Mixed
. Two Stage Activated Sludge
TRICKLING FILTERS
. Low Rate
. High Rate
STABILIZATION PONDS
PACKAGE AERATION PLANTS
ADVANCED WASTE TREATMENT
. Reverse Osmosis
. Activated Carbon
. Microscreening
. Deep Bed Sand Filtration
(Rapid sand filtration)
. Phosphorous Removal
(Chemical treatment)
. Ammonia Stripping CD
. Electrodlolytii
EFFL
o
2
15-65
er* in
Z
|
70
TITUEr
e-ch bo
*, bott
c
1
60-S5
W-95
<1
•ITS
r -
am in *
|
Z
£
i
50-80
<5
n
«
5
1
90-99
70-8$
2-4
<5
Suspended Solidl 1
<5-75
85-90
20- JO
60-80
80-100
74-94
17-29
100
60-80
< 7
30-80
3-5
60-85
<1
@
&
3
100
90
<5
1
60-100
80
1
MUTUAL
SCCTIOff
flicJtoround
Ops Oita
Probleam
L-l to C-JJ
11-19
IV 43-63
D-7 to D-9
11-22
IV 64-71
D-5 to D-6
11-21
IV 72-76
D-9 to D-ll
11-31
IV 77-79
D 13-14
11-31
C-l to E-8
11-24
VI 82-il
^-V function of pH and temperature
®Not all operations are used in all plants
In color units
All percent removals are based on process effluent to process influent
Table A-2
Classification Matrix of Treatment Systems
by Their Unit Operations, Removal Efficiencies
and Effluent Quality
A-7
-------
B
-------
PERSONNEL
-------
Appendix B
PERSONNEL REQUIREMENTS
This section of the manual contains information on personnel require-
ments for effective treatment plant operation. It lists the minimum skills
required for the various duties which are performed at treatment plants.
A manpower and work schedule is included to delineate the numbers of per-
sonnel and hours needed to perform the required work.
Table A-l (Appendix A) of this manual indicates the classification of
operator for plant size and treatment system. This data, along with the
information presented in this section, should be compared against personnel
information for the plant being evaluated to see if adequate staff (both in
numbers and qualifications) is being utilized. This should be included in
the overall evaluation rating given to the plant.
GENERAL SKILLS
The skill requirements outlined below are minimal for successful per-
formance of specific required duties. These are only a guide; additional
requirements for the particular plant location should be checked.
• Supervisory Personnel (level of ability depends on size and
type of plant) - high school education or equivalent, should
display better than average ability to:
1. Use and manipulate basic arithmetic and geometry.
2. Think in terms of general chemistry and physical
sciences.
3. Understand biological and biochemical actions.
4. Grasp meaning of written communications.
5. Express thoughts clearly and effectively, both
verbally and in writing.
In addition, supervisory personnel are often responsible for:
1. Public relations
2. Bookkeeping
3. Analysis and presentation of data
4. Budget requests
5. Report writing
6. Personnel
B-l
-------
7. Safety educational program
8. Contracts, specifications and codes
9. Estimates and costs
10. Plant library
• Laboratory Technicians - require training in laboratory pro-
cedures and mathematics
• Operating Personnel - require training in:
1. Fundamentals of wastewater treatment processes,
including chemistry and biology.
2. Mathematics (including geometry).
• Maintenance Personnel - must be familiar with and capable of:
1. Mechanical repairs
2. Electrical and electronic repairs.
MANPOWER AND WORK SCHEDULING
• Day-Shift Operators. 225 days/year at 6 hours/day = 1,350 hours/
year. Attempts to schedule workloads and staff plants on this
basis indicates that 5-1/2 hours/day is more realistic. This
value will drop as the number of phone calls, visitors , inspectors,
and emergencies increase.
• Night-Shift Operators. 7 hours/man/shift (fewer interruptions
and work is of the routine inspection and recording nature).
Table B-l shows ranges of the number of personnel which would be re-
quired to operate various modes of treatment systems. Each plant may have
its own particular operating mode, depending on the number of components
which make up liquid and sludge treatment, along with administrative and
general plant functions. The advanced waste treatment plants were not
included in this table because of the lack of reliable manpower estimates
for this classification.
B-2
-------
Table B-l
PLANT MANPOWER REQUIREMENTS*
Type of Plant Average Capacity (MOD)
13 5 10 20 35 50 65 80 100
Primary 4.5-6 6.5-7.5 7.5-9 10-13 15.5-19 22-27 29-34 34-41 40-49 50-59
Secondary (including 6-7 7.5-9.5 9.5-11.5 13-16 19.5-24 28-34 37-44 45-53 53-61 63.5-76.5
Trickling Filter)
Secondary (including 7-8 9.5^10.5 11.5-13 15-18 23-26 33-38 43-49 51-59 61-69 71-82
Activated Sludge)
*Based on a preliminary study performed by Black and Veatch for the EPA.
B-3
-------
-------
PRIMARY
TREATMENT MODE
(Background Info)
-------
7046
Appendix C
PRIMARY TREATMENT MODE
(Background Information)
This section of the manual contains background information on processes
generally used in preliminary and primary treatment of wastewater. It
describes the basic mechanisms of the various processes and how they fit
into the overall treatment scheme. A list of references for each process
is included for additional information.
The tables located in Section II of this manual list the common
preliminary and primary treatment operating parameters, loading rates ,
material accumulated during process operation, and support systems which are
used in conjunction with each process. If a general review of preliminary
and/or primary treatment is desired, review this section plus the applicable
tables in Section II, and the pertinent problems and solutions in Section IV.
GENERAL
Pretreatment of raw wastewater includes the removal of large pieces of
debris by passing it through a bar screen to remove large solids and then a
grinder (comminution) to reduce particle size of the remaining solids to
protect plant equipment and prevent plugging of pipes. This treatment also
includes degritting by sedimentation. After degritting, the wastewater goes
to the primary treatment where a sedimentation process removes a portion of
the suspended solids (SS) and the settleable solids, along with related
biochemical oxygen demand (BOD).
Figure C-l shows a pre- and primary treatment system. There are many
configurations that can be representative of this form of treatment, with
units being added or deleted on the basis of the degree of treatment
required, economics and space availability.
References shown after each description of a process provide additional
information on that particular process.
C-l
-------
7046
If no cutters
or shredders
screenings
Hauled to
sanitary landfill
or incinerator
i 1
1 Chemical addition '
I , ... I
i for precipitation |
Influent \ From combined system
or sanitary system
By Pass
Prechiorination wet well
Weir for flow control
CUTTERS
SHREDDERS
COMMINUTOR
PP.EAEPAT1OM
*-* r.r • rr o r%r\/
\^l\l_/-VJi- (Ji v-*Lyv
CONTROL
FINE SCREENS
SEDIMENTATION
LAGOONS
-fc
sludge
DIGESTER
CHLORINATION &
CONTACT CHAMBER
1
Secondary system
Effluent
discharge
r*
VACUUM
FILTER,
^Periodically
' scraped,
hauled
Hauled or
incinerated
Discharge
Fig. C-l. A Primary Treatment System
C-2
-------
7046
PRETREATMENT
Flow Regulators
Local conditions will determine the hourly variations in quantity and
strength of the wastewater. The regulation and metering of flow through the
treatment plant is accomplished by use of weirs and flumes for open channel
sections, and the venturi tube, orifice plate, Dahl flow tube and magnetic
flow meter for pipe flows.
Devices which measure flow in an open channel all operate with a head
loss. The parashall flume has the smallest head loss of all the commonly
used open channel flow meters and is the one commonly used. Some plants
utilize electronic sensors coupled with servo control units that operate
valves or other mechanisms for flow control or diversion to various parallel
units.
Racks and Screening Devices
Racks and screens are designed to remove floating matter and larger
suspended solids (mainly inorganic). Commonly used screening systems include
racks, coarse or medium, having either:
1. Fixed bars, either hand or mechanically cleaned, or
2. Movable racks, such as the cage rack.
/ //]/ trough
rack
a) Fixed Bar Rack b) Mechanically Cleaned Rack
Fig. C-2. Fixed Bar Racks
C-3
-------
7046
Figure O2a shows a cross-section of a fixed medium bar rack. This rack,
like the coarse rack, is primarily used to protect pumps. The medium rack
also removes floating material which will form a heavy and troublesome scum
in sedimentation basins.
For additional information see:
Chapter 4 of ASCE Sewage Treatment
Plant Design and Chapter 22 of
Water Supply and Sewage-Steel.
Grit Chambers
Grit chambers are installed prior to sedimentation and usually after
bar racks to remove dense mineral matter such as sand, gravel, egg shells
or cinders. Grit removal helps prevent problems in pumping sludge. Grit
chambers are also used to avoid the cementing effects on the bottom of the
sludge digester and in the sludge blanket of the primary settling tank.
They also are installed to prevent reduction of active digester capacity
and help prevent damage to mechanical equipment. These units are usually
installed in plants with combined flow; however, many of the newer plants
are designed with grit removal systems as common practice. Figure C-3 shows
a plan and a section view of the most common configuration of a grit chamber.
PLAN
SECTION
Fig. C-3. Grit Chamber
C-4
-------
7046
Removal mechanisms generally fall into one of four types:
1. Flow rate control which is maintained at 0.75 to 1.0 ft/sec
by proportional weirs, by controlling the depth of flow.
2. Clarifier-like mechanisms, sized to cause grit to fall out.
The grit is then cleaned by washing and the organics are
returned to the wastewater flow.
3. Hydraulic cyclone, removes grit by centrifugal force which
tends to force the heavier grit particles to the outside
of rotating flow stream. -
4. Injection of diffused air produces a spiral flow velocity
causing particles to settle out.
The average cleaning interval is every two weeks. In wet weather, and
particularly with combined wastewater flow, the accumulation of grit may be
enormously increased, necessitating rapid or continuous cleaning to keep the
unit operating efficiently.
For additional information see:
Ch. 23 of Steel; Ch. 4 of Imhoff-
Fair; and ASCE Sewage Treatment
Plant Design, Ch. 5.
Cutters , Shredders (comminutors)
Cutters and shredders are usually located after grit removal to prevent
excessive wear on cutting edges and before the sedimentation unit so the
shredded particles can be added back to the wastewater treatment stream and
removed by sedimentation. Generally, fine racks and fine screens have been
replaced by the cutting screens of communutors. These units are found in a
variety of sizes, capacities, and configurations. Those include up and down
moving cutting edges on bar racks and units that function like a kitchen sink
garbage disposal with rotating cutter edges.
For additional information see:
Ch. 22 of Steel; Ch. 3 of Imhoff-
Fair.
Fine Screens
Fine screens are used in old plants where cutters and comminutors were
not installed and in newer plants as partial treatment of certain industrial
wastes (e.g., cannery, brewery, distillery or packing house). They are
usually located after the grit and pre-aeration units and before the
sedimentation unit.
C-5
-------
7046
Fine screens may be made up of a series of disk screens with a frustum
of a cone superimposed upon it. It rotates slowly, with brushes sweeping
the screenings from the part above the wastewater flow to a conveyor belt
or hopper. Drum screens are of several types. Basically, screenings are
accumulated on the outside of a drum as it rotates or on the inside of a
drum as the flow passes through. Conveyors and collectors then handle the
retained solids.
For additional information, see:
Ch. 22, Steel; Ch. 3, Imhoff-Fair;
Ch. 4, ASCE Sewage Treatment Plant
Design.
Aeration and Chlorination
Aeration and Chlorination are utilized to minimize odor and grease
problems. Chlorine added to wastewater causes grease to coagulate. This
process also reduces the finely divided suspended solids load on the primary
sedimentation and biological treatment units. The cohesive force of the
wastewater is reduced by the diffused air bubbles that buoy up the grease
and suspended solids which are then skimmed off. This unit may follow the
grit chamber and cutters. It usually precedes the fine screens and/or
primary sedimentation unit.
For additional information, see:
Ch. 20, Fair & Geyer; Ch. 6, ASCE
Sewage Treatment Plant Design;
Ch. 3, Imhoff-Fair.
Sedimentation
Sedimentation (in primary treatment) usually follows grit removal,
screening and pre-aeration. It precedes final Chlorination and/or discharge
to the receiving waters or other effluent disposal areas. It reduces the
suspended solids and organic loading on subsequent secondary and advanced
waste treatment units.
Sedimentation tanks may be constructed with or without mechanical
devices for continuous removal of sludge. Tanks are classified by
• Primary - in which raw wastewater is settled
• Secondary of Final - in which mixed liquors or activated
sludge plants or trickling filter effluents are clarified
C-6
-------
7046
• Intermediate - when used between filters in a two-stage
trickling filter plant
• Septic tanks - combine sedimentation and sludge digestion
in the same compartment
• Imhoff tanks (two-story tanks) - combine sedimentation and
sludge digestion but are designed so that the processes are
carried on in separate compartments arranged one above the other
Municipal wastewater contains both granular and flocculent solids.
Based on this condition, the required capacity of primary settling tanks is
both a function of surface loading and of volume loading or detention period.
A number of factors affect the performance of sedimentation tanks and
the designs are influenced by those parameters which have the greatest
impact on the desired results. Some of the commonly considered parameters
are:
• Variation from 16-hour average flow
• Temperature variation (of the wastewater, as it affects the
density and viscosity of the liquid)
• Density currents
• Solids concentration
• Solids removal
The mechanism of sedimentation is based on the settling velocity of
particles. A particle in a still fluid of less density will move vertically
downward because of gravity. The time required for the optimum percentage
of these particles to drop out is the theoretical detention time of the
settling basin. This time varies with what the next treatment mode is.
Fig. C-4 shows the removal of suspended solids and BOD from wastewater in
primary settling tanks (after Imhoff and Fair) as it varies with detention
time. A secondary mechanism affecting the performance of the sedimentation
tank is its overflow rate. A case in point is a high overflow rate with
overflow velocities which exhibit a high scouring and solids-carrying
capacity in wastewater effluent. The allowable values of overflow rates
are dependent on the next mode of treatment.
07
-------
DDDB
7046
3 4
Tims, hours
Fig. C-4. Percent of Suspend Solids and BOD5
Both of these mechanisms are influenced by changes in the temperature
of the wastewater. By increasing the temperature, it reduces the viscosity
and density of the fluid, thereby increasing the settling velocity of the
particles and reducing the detention time required. Along with this,
characteristics of effluent quality over the overflow weir would be changed.
Figure C-5 shows the various types of sedimentation tanks and their
sludge collection systems.
For additional information, see:
URS Project 7032; Ch. 9 & 23,
Steel; Ch. 4, Imhoff-Fair; Ch. 3,
ASCE Sewage Treatment Plant
Design.
C-8
-------
o
REPRESENTATIVE
LONGITUDINAL-FLOW SETTLING TANKS
Rectangular, hand-cleaned
tank with sludge hopper
Tank a provided with track-
mounted sludge scraper
(Mieder tank)
Rectangular, hopper-
bottomed tank with
hydrostatic sludge
removal
:-^^-—---ri Square tank with cross flow
(d)
and rotary sludge scraper
(Dorr Co.)
,'v^ Rectangular tank with sludge
^i scraper and scum collector
(Link-Belt Co.)
MODIFIED IMHOFF TANKS
WITH SMALL SLUDGE SUMPS
Horizontal flow
Vertical and radial flow
REPRESENTATIVE VERTICAL &
RADIAL-FLOW SETTLE TANKS
Hopper-bottomed, circular
or square tank with hydrostatic
sludge removal (Dortmund tank)
— Tank i equipped with
sludge scraper
Tank
-J
O
c^i7.\i Tank e with cross collector
lilpJ! for sludge and scum
(Link-Belt Co.)
;_> Circular tank with sludge
collector to which scum
collector can be added
(Dorr Co. )
Fig. C-5. Settling Tanks
-------
7046
CHEMICAL PRECIPITATION
Chemical precipitation processes obtain effluent quality which is in
the range between primary sedimentation and the biological oxidation
processes. The most effective use of chemical precipitation is under the
conditions of seasonal variations in volume, strength or degree of treatment
required of the wastewater. In plants that are not specifically designed
for chemical precipitation, it is not uncommon for chemicals to be added
prior to primary or secondary sedimentation to aid in the settling process.
The process of chemical precipitation functions under one of three
mechanisms or under all three at the same time:
• Mechanical entrapment - heavy metal salts (such as alum or
ferric chloride), plus an alkaline material, produce large
volumes of precipitates which settle out true and colloidal
suspension in wastewater
• Particle charge - colloidal particles with electrical charges,
plus chemicals with opposite charges (polyelectrolytes) ,
neutralize each other and settle out
• Physical - insoluble chemicals (such as activated carbon)
with large surface areas either absorb or act as nuclei for
the colloids and start settling
As in primary sedimentation, detention time under quiescent conditions
is an important part of the processes, with detention times similar to
primary sedimentation.
For additional information, see:
Ch. 9, ASCE Sewage Treatment
Plant Design; Ch. 9 & 23, Steel.
CHLORINATION
Final chlorination is used to disinfect (destroy the pathogenic
organisms harmful to man or animals) treated effluents before they are
discharged to the final receiving waters. To accomplish disinfection,
enough chlorine is added to satisfy the chlorine demand of the waste while
leaving a chlorine residual to destroy the pathogenic organisms. The amount
of chlorine required for disinfection is largely dependent upon the organic
matter present. The performance of the chlorination process is affected by
the quantity of chlorine used, waste characteristics, where the chlorine is
applied and how well it is mixed. The contact chamber should have a cleaning
and flushing system to prevent buildup of sludge due to solids carry-over
from the final settling tank and grease. Figure C-6 shows a typical baffled
C-10
-------
Chlorine Contact Tank
Baffle
Baffle
A
U
Flow Control Weir
Final Effluent
to Receiving Water
Weir
Scum Baffle
Mixing Baffle
' Chlorine Diffuser
Influent
from Final
Treatment
Processes
Chlorine Source
PLAN VIEW
Baffle
Mixing Baffle
Flow Control Weir " Chlorine Diffuser
SECTION A-A
Fig. C-6. Final Chlorination System
C-ll
-------
7046
chamber. To be most effective, the contact time should be not less than
15 minutes at maximum flow.
There are some State health departments which require a residual of
2.0 mg/1 after 15 minutes. All such requirements should be checked before
plants are inspected.
There is a secondary benefit of proper effluent chlorination. At the
point where orthatoline residual is produced, each mg/1 of chlorine absorbed
will satisfy and remove approximately 2 mg/1 of BOD in the treated effluent.
C-12
-------
-------
SECONDARY
TREATMENT MODE
(Background Info)
-------
7046
Appendix D
SECONDARY TREATMENT
This section of the manual contains background information on pro-
cesses now being used in the secondary treatment process of wastewater.
It delineates the basic biological mechanism which takes place in the
various biological reactors, a description of these reactions and how they
fit into the treatment scheme, and a list of references for each process
for additional information.
The tables located in Section II of this manual list the common
secondary treatment operating parameters, loading rates, and support sys-
tems which are used in conjunction with each process. This information,
along with this section and the common problems and solutions for secondary
treatment (Section IV of this manual), should be reviewed for a general
background to expedite the plant evaluation and help in finding solutions
to process problems in this area.
As in pre- and primary treatment, there are many configurations that
can be representative of secondary treatment. The unit operations which
are shown in Figure D-l make up the basic secondary mode of treatment.
In secondary treatment, flow is received from the primary treatment
system. This flow then enters a biological reactor where biological
growth occurs. This growth "fixes" most of the remaining organic materials
in a biological mass (biomass). This biomass is then removed by sedimenta-
tion in the secondary clarifier. Some of the sludge (settled biomass) is
returned to the inlet of the biological reactor and is mixed with the
incoming primary effluent so that organisms with increased assimilation
capacities can work on the waste. The effluent from the secondary clarifier
is then chlorinated and discharged to the receiving body.
The biological reactors which are in common use in wastewater treat-
ment were listed in Appendix A of this manual. They can be operated in
many modes, depending on plant area limitations or treatment desirability.
In many cases the only prior requirement to the use of a biological reactor
is primary treatment.
D-l
-------
to
Wastewater
I
Pre-Treatment
Secondary Clarifier
1 1 1 1 1 1 1 1 1
> — - c ' 1 1 »
Primary Sedimentation f f Biological Reactor
-7 — r 1 1
11111111 i i
x i i
/ i I
llil
Lf-^ ©*-
^"^ 1 Slud
•- - 1 — Dinr
Trea
—— Ff fluent
ge
stion &
Irnent
— ^ Sludge
Wastewater
Effluent
To Final
Receiving Body
MM ^^ «M^ ^^m «^^
Chlorine
Contact
Chamber
1
1
Sludge
J
Final Sludge
Disposal
o
^
CD
Chlorination
Fig. D-l. Flow Diagram of a Secondary Treatment System
-------
7046
GENERAL BACKGROUND ON A BIOLOGICAL REACTOR
In nature, bacteria and other microorganisms break down organic
materials (the substrate) found in wastewater into simple, more stable
substances. A biological (aerobic) reactor provides a place where organic
waste is brought into contact with the surface, contact, or interfacial
forces of biological slimes, or films, zoogleal aggregates, activated
sludges or activated surfaces to remove suspended and finely divided solids
and dissolved organic matter by the mechanisms of adsorption and coagulation,
and enzyme complexing. Whatever the individual operation of the biological
reactor, the microorganisms which stabilize the wastewater must have a
continuous supply of substrate (food) , an adequate supply of oxygen
(aerobic systems only) and a suitable supporting film of floe.
The reactions involved in the reduction of organic material in the
wastewater during biological oxidation can be interpreted as a three-phase
process:
1. an initial removal of BOD on the contact of a waste with a
biologically active sludge or film which is stored in the
cells of the organism as a reserve food source
2. removal of BOD in direct proportion to biological sludge
or film growth
3. oxidation of biological cellular material through endogenous
respiration.
For additional information, see:
Ch. 2, Eckenfelder & O'Connor;
Ch. 1, Rich Unit Process;
Ch. 6, Imhoff-Fair.
D-3
-------
7046
TRICKLING FILTERS
A trickling filter is a fixed bed system over which wastewater is
intermittently or continuously discharged and contacted with biological
films on the filter media. Through this contact nonsettleable suspended
matter and colloidal and dissolved organic matter are removed from settled
wastewater by the organisms to be used as food.
A schematic representation of mechanism involved in the trickling
filter processes is shown in Figure D-2. The largest portion of the waste-
water applied to the surface of the filter passes rapidly through the filter,
and the remainder slowly trickles over the surface of the slime growth.
The reduction of organic loading occurs in two stages:
• the wastewater passes rapidly through the filter and
removal occurs by biosorption and coagulation
• soluble constituents are removed from the remaining
portion of flow due to the substrate utilization by
the organisms.
WASTEWATER
AIR
AIR \
I -n
m —
^5
j> m
\\X\\\\\\\\\\\\\\\\\\\\\\
H2S
ORGANIC
ACIDS
ANAEROBIC
EFFECTIVE
FILM DEPTH
-* h *•
BOD
°2
co2
AEROBIC
WASTE
1 1
i i
AIR
Fig. D-2. Trickling Filter
D-4
-------
7046
Classification of Trickling Filters
Filter classification is based on applied hydraulic and organic (BOD)
loadings (Section II of this manual shows typical loading rates).
• Low-Rate (Standard or Conventional Filter) - Low-rate filters
usually operate with intermittent dosing. The wastewater is
applied to the filter surface and passes through the filter
with its effluent going to the secondary clarifier without
recirculation. The filter depth is usually greater than for
high-rate filters.
• High-Rate - Wastewater is applied much in the same manner as
in the low-rate filter. However, the hydraulic loading is
five to fifteen times as great, with the organic loading
being four to five times greater. Along with the higher
loading rates , the high-rate filter is characterized by the
recirculation of a portion of the wastewater.
• Roughing Filter - Roughing filters are used to reduce the
organic load applied to subsequent filters of activated
sludge units. They are designed on the basis of the
volume of liquid applied to filter. They will also handle
a greater organic loading than low- or high-rate filters,
but with reduced removal efficiencies.
Trickling filters , like most biological reactors, are followed by a
final sedimentation process to remove any biomass which is lost from the
reactor. This final sedimentation process is figured in total process
efficiency when it is calculated.
For additional information, see:
Ch. 6, Eckenfelder-O'Connor;
Ch. 24, Steel;
Ch. 6, Washington State Waste-
water Plant Operation Manual;
WPCF Publication No. 14,
Sec. 15, Ch. 11, ASCE Treat-
ment Plant Design.
D-5
-------
7046
ACTIVATED SLUDGE
The activated sludge process is based on the utilization of a floe
made up of microorganisms, non-living organic matter and inorganic materials.
These are brought into contact with primary treated wastewater (in most
cases) in the presence of dissolved oxygen. A high degree of mixing causes
the removal of settleable solids, nonsettleable suspended solids, colloidal
solids and dissolved organic matter.
The basic process flow includes:
• Aeration of pre-primary treated wastewater for a
period of time
• Final clarification for the separation of solids and
liquids at the end of the contact time
• The return of a percentage of the separated solids to
the reactor for mixing with influent wastewater
• Discharge of the liquid wastewater fraction as
process effluent.
Classification of Activated Sludge Processes
• Conventional (plug flow). All primary-
introduced at one end of the reactor a]
sludge. The length of the reactor
width. The diffusers are located i
tank so that the diffused air bull
rolling motion on an axis parallel £to th.e/*4hMh of the tank.
This class of activated sludge process prtoviWes insufficient
dissolved oxygen content at the influent part of the reactor.
• Modified (high-rate). This process utilizes short aeration
periods and low activated sludge concentrations. It is
characterized by low BOD removals (40-70) and a low percentage
of sludge return (10%). Also associated with this process is
a high solids accumulation due to insufficient time for
significant oxidation of cellular mass and the retention of
influent inerts.
• Step Aeration. Primary treated wastewater enters this
reaction at a number of different points along one side of
the reactor, but with the returned sludge being introduced
at the point of first entry, with or without a portion of the
incoming wastewater. The greatest concentration of sludge
solids in the mixed liquid is where the final amount of waste
is introduced and decreases as more waste is introduced at
subsequent points. By entering the waste in this manner, a
more uniform aeration of the waste occurs, and a decrease in
detention time is possible.
D-6
-------
7046
Tapered Separation. Basically the same concept as step
aeration except that the air is added in stages along the
reactor instead of the wastewater. The air requirements
are staged to give maximum amount at the inlet of the raw
waste with the rest regulated to meet oxygen utilization
in other sections of the reactor. This process is supposed
to provide better control in meeting shock loadings.
Kraus Process. This is a modification of conventional
activated sludge where incoming wastewater (primary treated
water) has insufficient amount of nutrients (usually nitrogen)
available to provide a stable activated sludge process. These
nutrients are provided by the recycling of digester mixed
liquor to the activated sludge system by means of a nitTTrfica-
tion tank where a mixture of supernatant and returned activated
is aeratec/f24yhours and returned to the activated sludge
unit? Jfeiek),.fromVTrtyppiying the needed nutrients , there are
other beneficial effects from this process: it provides an
oxygen reserve in the form of nitrates and also tends to weight
the sludge thus providing better settling characteristics.
Completely Mixed Reactor. The primary treated waste is
completely mixed throughout the reactor as quickly as possible.
The process provides for immediate distribution for all incom-
ing waste, and the oxygen requirement throughout the tank is
uniform. This process minimizes the effect of slug loadings
of very strong waste or short term, high volume wastes (shock
loadings).
Contact Stabilization. Incoming primary-treated wastes (some
new plants omit primary sedimentation) are mixed with returned
sludge in a contact basin for a period of 30 minutes to one
hour in which most of the absorption of solids is accomplished.
This short contact permits solubilization of the absorbed
organic solids before the absorption by microorganisms in the
activated sludge of the soluble organics. This process is
also affected by a highly variable influent flow rate which
reduces the adsorption time causing high effluent BOD.
Two Stage Aeration. This is basically the same as contact
stabilization except that the contact time is six times as
long, providing enough time for absorption, solubilization,
absorption and the synthesis of cellular material. The
aeration time of the second reactor is long enough to provide
for the oxidation of a large portion of the synthesized cell
mass.
D-7
-------
7046
Extended Aeration. This type of system is usually provided
for a small-sized treatment facility. This system is
completely mixed with a low food/microorganisms (F/lW)
loading rate for a given population, which allows for almost
complete oxidation of synthesized cell mass. It is also
characterized by low oxygen uptake rate.
For additional information, see:
Ch. 2, 3 & 6, Eckenfelder-
CD 'Connor;
Ch. 6, State of Washington
Wastewater Plant Operators
Manual;
Ch. 25, Steel;
Ch. 10, ASCE Sewage Treatment
Plant Design.
STABILIZATION PONDS AND LAGOONS
The operation of stabilization ponds and lagoons that are aerobic
depends on oxidation and reduction by microorganisms, sedimentation, bio-
flocculation and anaerobic digestion of bottom sludge. The oxygen utilized
in this process is obtained from the algae growth present or mechanical and
diffused aerators with additional oxygenation being provided by wind and
wave action. Some ponds operate anaerobically in much the same way as a
digester with sufficient depth to create anaerobic conditions due to poor
oxygen transfer to the deep parts of the pond.
!
The effluent from this treatment process is disposed of by percolation
(where ground water regulations permit), evaporation, transpiration from
irrigation of cover crops or discharged to a receiving body.
Classification of Stabilization Ponds and Lagoons
The classification of stabilization ponds and lagoons may be according
to: depth, main source of oxygen, rate of waste loadings (Ib of BOD per
acre per day), inlet, flow-through, and inlet and outlet arrangements
including load distribution, recirculation, and effluent disposal. In
general, stabilization ponds and lagoons may be classified into three types:
» Large Holding Reservoirs. These are characterized by long
detention times (months, usually) with the oxygen being
supplied by surface aeration and dilution of the wastewater
with clean water. The removal of organics is accomplished by
bio-flocculation, oxidation, and reduction with an aerobic
digestion of bottom sludge taking place.
D-8
-------
7046
o Stabilization Ponds. The rate of oxidation of organic
matter by microorganisms exceeds the rate of natural surface
aeration and the algal growths must supply the additional
oxygen required. Since solar energy is required for photo-
synthesis, the depth of the ponds is limited. Location is
also a limiting factor as climatic parameters are very
important. The detention times in stabilization ponds
range from less than a week up to six weeks , depending on
the type.
a. Facultative Ponds. This type of pond is characterized
by the aerobic and anaerobic processes occurring
simultaneously. The removal of organic material is
accomplished by sedimentation, bio-flocculation and
aerobic oxidation. The primary source of oxygen is
obtained from algae growth with a second source
supplied by wind and wave action.
b. High Rate Ponds. This pond is characterized by its
shallow depths for extreme solar energy penetration;
it is fully mixed and completely aerobic. The organics
iii this system are oxidized by microorganisms utilizing
oxygen generated by algal growths.
o Aerated Lagoon. This system is characterized by the use of
mechanical aeration to supply the required oxygen supply
directly, causing sufficient mixing to supply additional
oxygen from surface aeration, so that the lagoon remains
aerobic.
For additional information, see:
Ch. 6, Eckenfelder-O'Connor;
Ch. 12, ASCE STP Design
Ch. 21, Steel.
INTERMITTENT SAND FILTERS
Intermittent sand filters are being phased out of secondary waste
treatment mode due to the large area requirements. Because of the high
quality effluent produced, they may be used in advanced waste treatment
modes on a smaller scale to polish secondary treatment effluent.
The basic mechanism of this process is a straining effect produced
by sand grains which trap suspended solids. The intermittent dosing
(twice during a 24-hr period) permits air to enter the bed to allow micro-
organisms to reduce the organic load aerobically. It should be noted that
work done by Grantham, Emerson and Henry in Florida indicates that sand
D-9
-------
7046
size affects the percentage of organic material removed.
For additional information, see;
Ch. 12, ASCE STP;
Ch. 24, Steel.
SECONDARY CLARIFICATION
This unit follows the biological reactor (such as the trickling filter
of activated sludge). Its primary functions are to retain the biological
growths produced by the reactor for recycling and to produce clarified
liquid in the overflow and thickening on the bottom of the tank. This
depends on the physical and chemical nature of the sludge and the hydraulic
characteristics of the clarifier.
The clarifiers can be rectangular or circular in shape. In both types
of clarifiers, their size is related to one of the following factors:
• Surface of clarifier area over the M.L.S.S. concentration
• Surface area and volume of clarifier for producing thickening
and underflow of a desired concentration
• Volume for retention of settled sludge
Along with these requirements, the velocity of the density currents are
critical in the clarifier. If these velocities are increased, the critical
value for separation of solids could be exceeded causing bottom scour with
the possibility of carryover of low density particles in the effluent.
For additional information, see:
Ch. 4, Rich, Unit Operations of
Sanitary Engineering;
Ch. 5, Eckenfelder-O'Connor;
Paper by Clair Sawyer - Final
Clarifiers, and Clarifier
Mechanisms (MIT);
Ch. 8, ASCESTD.
D-10
-------
7046
PACKAGE AERATION PLANTS
This type of treatment system is characterized by
• low daily flow
• no primary sedimentation
• 20-24 hour aeration period
• long final sedimentation period
• limited flow control between processes due to close
proximity of operations.
The basic mechanism of the process is to keep the microorganisms predomi-
nantly in the endogenous growth phase (organisms are using all material in
absence of organic material growth) through long detention time and a low
food-to-microorganism ratio in the aeration tank.
Two systems in common use consist of:
• aeration tank and final sedimentation tank plus chlorination
• mixing chambers, sedimentation tank, and sludge reaeration
tank plus chlorination.
Both of the systems utilize aerated digestion of the activated sludge.
Critical to successful operation of these plants is a program of effective
solids removal from the system.
For additional information, see:
"Aeration Plant in Florida",
ASCE Jour, of Sanitary Eng.,
Vol. 88;
"Field Evaluation of the
Performance of Extended
Aeration Plant", J. WPCF,
Vol. 41, July 1969, p. 1299.
D-ll
-------
-------
ADVANCED
TREATMENT MODE
(Background Info)
-------
7046
Appendix E
ADVANCED WASTEWATER TREATMENT
Advanced wastewater treatment processes are described in this section
of the manual. It delineates how the process works, the various organic
and inorganic constituents which are removed by the processes, removal
percentages which can be expected, and references for additional information.
The tables in Section II of this manual list the common advanced
waste treatment operating parameters, a range of materials accumulated due to
process operation, and support systems which are used in conjunction with
each process. This operating information, together with the common problems
and suggested solutions , should be reviewed with the information in this
section to provide background data against which an advanced waste treatment
plant can be evaluated.
GENERAL BACKGROUND
In the past few years the United States has experienced rapid popula-
tion growth, concentration of people in urban areas, and the appearance of
ever larger industrial establishments. All of these factors have contributed
to increased pollutional loads on streams, rivers, and other receiving
waters. The result has been that conventional primary and secondary treat-
ment processes are not always able to provide adequate removal of pollutants.
For this reason, advanced waste treatment processes have been developed to
remove pollutants not handled by conventional (primary and secondary)
treatment. Advanced waste treatment is intended, therefore, to alleviate
pollution of a receiving watercourse. It may also, however, be used to
provide a water quality adequate for reuse, since the population expansion
and increased water demand mean that more and more people have water supplies
that must be used more than once for industrial and domestic purposes.
It should be pointed out that certain materials to be removed by
advanced waste treatment are normally removed to a great extent by secondary
treatment (e.g. , 90 to 95 percent of suspended solids are removed in an
efficient secondary plant). Advanced waste treatment, which is important
whenever upsets occur in such a secondary plant, is physical-chemical
treatment. This process, due to its reliability, could also be used in
cases where direct water reuse is anticipated and 90 to 95 percent removal
is inadequate. Advanced waste treatment is more commonly used, however,
for materials which are not efficiently removed by primary or secondary
treatment (e.g., phosphates and nitrates).
E-l
-------
7046
In general, advanced waste treatment is applied to effluent from
conventional secondary processes for the purpose of removing one or more of
the following constituents: soluble organic compounds, soluble inorganic
compounds (nitrogen and phosphorus), particulate solid material, and
pathogenic organisms.
The following paragraphs examine selected advanced waste treatment
unit operations to provide descriptions of the processes involved and
present references of interest for additional detailed information.
CHEMICAL/PHYSICAL TREATMENT
Chemical precipitation and sedimentation is a treatment method
combining chemical and physical elements to achieve removal of soluble
inorganic compounds (such as phosphorus) or removal of suspended solids in
a colloidal state. A mineral or synthetic polymer is added to the wastewater
and chemically reacts with one or more constituents of the wastewater to
produce a precipitant. This precipitant is then coagulated or flocculated
by means of the mechanical action of mixing or the addition of a coagulation/
flocculation aid. The precipitant is subsequently removed by sedimentation.
In this process, constituents of the wastewater are removed in several ways:
• chemical reaction with the material added and sedimentation
of the resulting precipitant
• physical capture of suspended solids by the descending
precipitant
• adsorption of particles and dissolved constituents by
the precipitant.
Removal of phosphorus is typically obtained by addition of calcium, aluminum,
or iron salts (e.g., lime, alum or ferric chloride). Phosphorus removals
vary from about 70 to 95 percent.
Chemical/physical treatment can be applied to secondary effluent or
to primary effluent. In an activated sludge plant, efficient removals have
been achieved by mineral addition before primary settling, after primary
settling, in the aeration tank, or near the mixed liquor exit point. In a
trickling filter plant, the precipitation is usually accomplished in the
primary sedimentation tank. Final chlorination and discharge to receiving
water follows chemical/physical treatment after it is used in secondary or
advanced waste treatment.
Chemical/physical treatment is basically a sedimentation process and
has associated with it the same type of equipment and performance parameters
as in primary or secondary sedimentation. Additional equipment is, however,
required to store and feed the required additional materials into the
sedimentation tank. Specialized equipment and instrumentation are necessary
E-2
-------
7046
since slurries often are involved and pH control is critical.
For additional information, see:
Ch. 2, Gulp and Gulp
Ch. 26, 29 and 30, Fair, Geyer
and Okun
Advanced Waste Treatment Research
Series AWTR-2, -12
Advanced Waste Treatment Seminar,
Session II (Oct. 1970)
CARBON ADSORPTION
Carbon adsorption is a treatment method used to remove residual
dissolved and suspended organic material from wastewater treatment plant
effluents. These organic pollutants are typically responsible for the color,
odor, taste, and froth problems of wastewater. In carbon adsorption, the
wastewater is continuously run through a bed or column of activated carbon
which removes the organic materials by adsorption. When the adsorption
capacity of the columns is exhausted, the wastewater is rerouted through
another bed of carbon and the exhausted carbon is regenerated for use again.
In actual plant experience (South Tahoe) , the carbon adsorption process
has yielded the influent entering it the following removals: BOD - 70+%;
COD - 50+%; TOC - 75%; color - 75%. In pilot plant tests, removals of
suspended solids have run up to 90% and removal efficiencies even greater
than those shown above have been experienced.
Conventional primary and secondary treatment removes organic matter
to a great extent. The difficult-to-remove organics (refractory organics)
are handled by carbon adsorption. Carbon adsorption, therefore, follows
secondary treatment and precedes chlorination.
The activated carbon must be of the proper type to adsorb materials
present in the existing wastewater. Many different types are available,
and the actual type and quantity to use depend on the kind and concentra-
tions of pollutants to be removed. In addition to variations in the
adsorption characteristics, activated carbon also varies in physical form
from powdered to granular. Since the carbon is stressed during regenera-
tion and transported between generations, it must be durable to such
stresses and still maintain performance. The granular carbon is generally
optimum from an overall cost performance, endurance, and recovery point
of view.
The carbon columns may run from 8 to 12 ft in diameter and 24 to 60 ft
tall. Usual operation is to run the wastewater through from two to four
columns in series. The most important factors in column operation are
E-3
-------
7046
contact time, pretreatment, and flow conditions within the column itself.
For regeneration, the spent carbon is transported from the column in
water slurry and fed by screw conveyor into a regeneration furnace where
intense heat burns off accumulated material, opening the interstices of
carbon for additional adsorption. Makeup carbon is added as needed and
the regenerated carbon is returned to the column (again in the slurry).
For additional information, see:
Ch. 7 and 8, Gulp and Gulp
Ch. 26, Fair, Geyer and Okun
Advanced Waste Treatment Research
Series 9, 10, 11 and 16
Advanced Waste Treatment Seminar,
Section III.
AMMONIA STRIPPING
Ammonia stripping is a treatment method for specific removal of nitrogen
in the form of ammonia. The process is one in which the wastewater is cas-
caded down a stripping tower and air is forced up through the tower. The
air strips the dissolved ammonia from the water and carries it off into the
atmosphere. Removal efficiencies up to 90% have been achieved.
Neither conventional primary nor secondary treatment removes significant
amounts of nitrogen, but the biological process does convert nitrogen com-
pounds in the wastewater into ammonia. Ammonia stripping, therefore, follows
secondary treatment and precedes chlorination.
Effective ammonia stripping requires a high pH and high air-to-liquid
loadings. Both of these factors are temperature dependent, such that when
air temperatures are lower, the corresponding pH and air loadings must be
higher to give the same ammonia removal. Normal operation calls for a pH
of above 11 and air rates of from 200 to 500 cfm/gpm.
Actual ammonia stripping towers are very similar to forced-draft type
cooling towers. The pH adjustment takes place before entry of the waste-
water to the stripping tower. In a typical operation, the pH adjustment,
using lime and a phosphorus removal step, takes place in a clarifier just
before feeding the wastewater to the stripping tower. After passage through
the tower, recarbonation is performed to readjust pH as needed to prepare
the wastewater for filtration, carbon adsorption, chlorination, or final
discharge. In the recarbonation process, an intermediate reaction or
settling basin exists between the two recarbonation basins. In the settling
basin, a dense floe rich in calcium carbonate is formed, and this is a
source of material to reclaim lime for reuse.
E-4
-------
7046
In an advanced waste treatment scheme, therefore, the secondary
effluent proceeds through a chemical/physical treatment for phosphorus
removal, then ammonia stripping, carbon adsorption, and finally filtration
and/or desalting.
Two problems that may occur with ammonia stripping are: 1) the
inability to operate at air temperatures below 32 F; and 2) the deposition
of calcium carbonate scale on stripping tower surfaces.
For additional information, see:
Ch. 4 and 5, Gulp and Culp
Ch. 28 and 31, Fair, Geyer and
Okun
Advanced Waste Treatment Seminar,
Session 1.
ELECTRODIALYSIS
Electrodialysis is a membrane desalting process for removal of dis-
solved inorganic ions from wastewater. In the process, membranes are used
which are permeable to charged ions and impermeable to ions of the opposite
charge. A pair of opposite membranes has a direct current potential applied
across them and the wastewater is pumped between them. Positive and negative
ions, therefore, permeate out of the wastewater, and a product with lower
dissolved minerals results. In addition, a brine stream very concentrated
in dissolved minerals also results. Electrodialysis is capable of yielding
product water with up to 85% of the total dissolved solids removed. In this
process , nitrogen removal is about the same as total dissolved solids , but
phosphorus and CO do not show the same high removal. A typical system will
yield about three gallons of product water and one gallon of brine for every
four gallons of feedwater treated.
Conventional primary and secondary treatment does not remove significant
amounts of dissolved inorganics. Electrodialysis usually follows carbon
adsorption which removes constituents capable of fouling the electrodialysis
membranes (non-ionic particles).
Normal operation of electrodialysis requires pH control, chemical
control of scale formation, and routine flushing and cleaning of membrane
surfaces. Proper disposal of the brine stream is important and this may
consist of ocean dumping (where it is still permitted), evaporation pond
utilization, or deep well injection.
E-5
-------
7046
For additional information, see:
Ch. 21 and 30, Fair, Geyer and
Okun
Advanced Waste Treatment Seminar,
Section IV.
REVERSE OSMOSIS
Reverse osmosis is a membrane desalting process for removal of
dissolved inorganic materials from wastewater. In the process, membranes
are used which are permeable to pure water, but nearly impermeable to
dissolved salts when operated at high pressure. Product water with lower
dissolved minerals is forced through the membrane, and a brine stream very
concentrated in dissolved minerals is rejected by the membrane. Reverse
osmosis is capable of yielding product water with up to 85% of the total
dissolved solids removed. In this process, phosphorus, COD, and ammonia-
type nitrogen are removed about as efficiently as the total dissolved
solids, but nitrate-type nitrogen is less efficiently removed. A typical
system will yield about three gallons of product water and one gallon of
brine for every four gallons of feedwater treated.
Conventional primary and secondary treatment does not remove signifi-
cant .amounts of dissolved inorganics. Reverse osmosis usually follows
carbon adsorption in an advanced waste treatment scheme so that fouling of
membranes is avoided.
Normal operation of reverse osmosis requires pH control, chemical
control of scale formation, and routine flushing and clearing of membrane
surfaces. Proper disposal of the brine stream is important, and this may
consist of ocean dumping, if still permitted, evaporation pond utilization,
or deep well injection.
For additional information, see:
Ch. 21 and 30, Fair, Geyer and
Okun
Ch. 10, Gulp and Gulp
Advanced Waste Treatment Seminar,
Section IV.
E-6
-------
-------
SOLIDS TREATMENT
AND DISPOSAL
-------
Appendix F
SOLIDS TREATMENT AND DISPOSAL
This section of the manual supplies background information on the
various processes involved in handling and treating of solids accumulated
during the wastewater treatment process.
Sludges are characterized by their percentage water content, volatile
matter, and the various processes by which they are produced. In addition,
this section explains the methods available for final solids disposal.
A comparison of operational parameters and loading rates (design specifica-
tion) with those presented in this manual or in other sources will facili-
tate an evaluation of the solids treatment and disposal system. Deviations
from normal will reveal any problem areas. A check of the common operating
parameters, loading rates, and support systems which are generally used in
solids handling (Tables II-5 and II-6 in Section II) should also be made.
These tables, along with the common problems in solids handling (Section IV),
and a review of this section will supply information needed for a general
evaluation of the solids handling program carried on at the wastewater
treatment plant.
GENERAL BACKGROUND
The solids accumulated from the various wastewater treatment processes
can be grouped into one of two categories: those trapped on medium and fine
screens in pretreatment, and those formed from processes in the primary,
secondary and advanced treatment modes.
Large-size material trapped by racks, such as glass bottles, rags, or
pieces of wood, is collected and usually buried in a sanitary landfill.
The solids from medium screening are shredded and treated by anaerobic
digestion, along with fine-screen solids.
Settled solids (from primary and secondary treatment) can be treated
by combinations of thickening, anaerobic and aerobic digestion, condition-
ing elutriation; or with chemicals, vacuum filtration and drying on beds or
in kilns.
The final disposal of wet sludge is accomplished by dumping or piping
it to sea or by incineration; dried or dewatered sludges are also inciner-
ated, used as soil conditioners, or buried in sanitary landfills.
F-l
-------
TREATMENT OF SLUDGE
The water content of sludge is the controlling factor as to the volume
of sludge produced. Sludge can be characterized by the type of process by
which it was produced. The following table characterizes sludges produced
by the various processes.
Table F-l
SLUDGE CHARACTERISTICS
Process Producing Sludge
Percent
Water
Content
Volatile Matter
as Percentage of
Dry Solids
Primary sedimentation sludge 94 - 96*
Activated sludge 95 - 97.5
High rate
Trickling filter 96 - 97
Chemical precipitation 95
Digested sludge (well digested)
• Primary 88 - 94
• Primary and activated 94 - 96
• Primary and trickling filter 90 - 94
70
45-70
32-45
* Steel, Water Supply and Sewage, pp. 574-575
The Digestion Process
Anaerobic organisms break down complex molecular structures of the
solids and release much of the bound water, while obtaining nutrients
and energy from the conversion of the raw solids into more stable organic
and inorganic solids. Anaerobic sludge digestion takes place in three
phases:
a Acid fermentation. Soluble or dissolved solids are broken
down into simple organic acids (volatile acids) with a
decrease of pH.
F- 2
-------
• Acid regression. The organic acids and nitrogenous
compounds are decomposed with an increase in pH.
• Methane production. This occurs simultaneously with
the first two phases. Methane bacteria reduce the
organic acids and other products of the first and
second phases to produce methane and carbon dioxide gases.
Sludge digestion accomplishes the following:
• Reduces organic matter into simple compounds
• Reduces sludge volume
• Releases the remaining water more easily
• Reduces the coliforms by 99.8 percent in 30 days
Aerobic Sludge Digestion
This particular process functions in much the same way as an activated
sludge unit, with the feed to the aeration tank being sludge from the
primary and secondary sedimentation basins. This process requires adequate
mixing and a dissolved oxygen level range of 1.0 to 1.5 mg/1. The deten-
tion time required for treatment of sludge is from 20 to 30 days with
removals of supernatants and sludge from the digester to maintain a consis-
tent feed rate.
For additional information, see:
Ch. 6, Washington State Treatment
Plant Operator's Manual
Ch. 1 and 7, Eckenfelder-O'Connor
Ch. 14, ASCE STP Design
Ch. 26, Steel
Ch. 12, Imhoff-Fair
SLUDGE THICKENING
This process, usually found in the larger treatment plants, precedes
digestion, vacuum filtration, or kiln drying. Sludge thickening is used
to reduce the liquid volume of the sludge solids which have to be pumped
to other treatment units. These treatment units then can be smaller
because they do not have to handle the excess liquid.
F-3
-------
There are two major types of sludge thickening operations:
• Gravity thickening. Sludge and aerated secondary effluent
are introduced into a basin, much like a stirred sedi-
mentation basin except deeper, which allows the concentration
of solids from flocculation by interfacial contact and
compaction by the weight of the overlaying water. This
method can produce a solids content of 8% or greater.
Not all sludge combinations will work in a gravity thick-
ener, and testing of sludge produced by the treatment
process will be necessary. In some cases, the addition
of chemical flocculant will aid in the concentration of
the sludge.
« Flotation thickening. This is usually used on sludges
formed by biological reactors. This process combines
sludge with a liquid which has been exposed to high
pressure and contains large amounts of dissolved oxygen.
Under less pressure in the thickening tank, air bubbles
from the liquid attach themselves to the sludge particles
and rise to the surface where the sludge is collected
for further treatment.
For additional information, see:
Ch. 15, ASCE STP Design
Ch. 6, Washington State Treatment
Plant Operator's Manual
Ch. 26, Steel
Ch. 14, Imhoff-Fair
SLUDGE CONDITIONING
The basic processes which are used in sludge conditioning are
elutriation and chemical conditioning.
• Elutriation consists of mixing thoroughly 1 part of
sludge with 2 parts of water and allowing separation
of about 6 hours, followed by decanting the resulting
elutriate and drawing off the sludge.
• Chemical conditioning consists of the addition of cer-
tain chemicals to coalesce particles in sludge which
facilitates moisture removal by filtration. Some of
the chemicals commonly used are:
F-4
-------
DOE
Ferric chloride
Ferric sulfate
Lime and ferric chloride
Chlorinated coppeas
Aluminum sulfate
Chemical solutions
Polyelectrolytes
Activated silicates
Inorganic polyelectrolytes
For additional information, see:
Ch. 15, ASCE STP
Ch. 26, Steel
Ch. 14, Imhoff-Fair
SLUDGE DEWATERING
Some common methods for sludge dewatering are vacuum filtration,
centrifuging, and sludge drying.
• Vacuum Filtration is widely used in the separation of
liquids from concentrated suspensions, sludges, and
slurries. The basic mechanism of this process is the
passing of a cylindrical drum which rotates partly
submerged through a container of sludge. The solids
in the container are agitated to keep them in suspension.
A vacuum which is applied between the drum deck and
filter media causes the water to be removed while sludge is
held on the filter media. Following this process, the sludge
is buried in a sanitary landfill or incinerated. The
supernatant can be disposed of by returning it to the
elutriation tank or returned into the influent of the
plant.
e Centrifuging removes water by centrifugal force which
tends to force the heavier solids to the outside of the
rotating flow stream much like the spin dry cycle of a
washing machine.
• Sludge Drying is best suited for sludges which have been
digested. The mechanism is that of a shallow sand filter
for draining the sludge and air for drying in beds. The
supernatant may be disposed of in the same manner as
vacuum filtration liquids.
F-5
-------
For additional information, see:
Ch. 7, Rich - Unit Operations of
Sanitary Engineering
Ch. 26, Steel
Ch. 15, ASCE STP Design
Ch. 14, Imhoff-Fair
DISPOSAL OF SLUDGE
The final disposal of sludge is influenced by many factors:
• The character, and composition of the sludge
• Availability of land for dumping of sludge cake or
lagooning of wet sludge
• Whether or not regulatory agencies allow piping (deep
water sludge outfall) or barging of sludge
• Local market possibilities for its use as fertilizer.
Coastal cities can dispose of sludge through barging or piping
to sea, where still allowed. On land, it may be buried in swamps, abandoned
quarries, and other lands which have no present use.
Incineration of raw or digested dewatered sludge is gaining popularity.
At present, only larger cities are utilizing this process because of its
added expense. In general, incineration of sludge is a wet combustion
process in which sludge in solution or suspension goes through chemical
oxidation processes under pressure.
For additional information, see:
Ch. 14, Rich - Unit Processes of
Sanitary Engineering
Ch. 15, ASCE STP Design
Ch. 26, Steel
Short Course - Theory and Design
of Advanced Waste Treatment
Processes, U.C. Berkeley Extension
F-6
-------
-------
CONTROL AND
METERING SYSTEMS
-------
7046
Appendix G
CONTROL AND METERING SYSTEMS
Various control and metering systems which are in common use in waste-
water treatment plants are described in this section. It also indicates the
uses and the limitations of these devices. The limitations are a function
of physical/chemical makeup of the wastewater, the type of treatment units
employed, sophistication of the plant personnel, economics, and the plant's
maintenance program.
A comparison of devices indicated in this section should be made with
those that will be encountered at the treatment plant to see if they are
types which will supply the data needed and required to maintain proper plant
performance.
The section on Problems and Solutions indicated the various problems
which are commonly encountered with existing metering devices to help with
solutions.
CONTROL SYSTEMS
Wastewater treatment plants use a variety of treatment processes.
These processes usually fall into four categories: physical, biological,
chemical, and electrochemical. In most plants, the processes are affected
by temperature, weather, and day-to-day load variations. The nature of
wastewater being high in solids' content and the inability of sensors to
withstand fouling due to these solids makes total automation (computer
control of the process) infeasible at the present time.
Most treatment plants in existence today use instrumentation which
involves the measurement of physical variables, such as flow, level,
pressure, and temperature. These controls are electric and pneumatic
mechanisms in conjunction with hydraulic equipment. These controls can be
divided into two basic types:
• On-off - used for the activation of pumps, alarms, etc.
• Modulating - where the regulation of valves or other
equipment is accomplished in proportion to a measurement
(ratio control).
The treatment systems utilize these controls to regulate or determine
recirculation rates or controllers that set recirculation flow at a ratio to
some other variable. The greatest present use for instruments and controls
is in the treatment of sludge, where the use of density monitoring equipment
to maintain optimum raw sludge density in the digester is becoming common.
G-l
-------
7046
Other examples of automated control include: temperature control, gas volume
sampling, and sludge level measuring equipment.
What most systems lack is redundancy; there are no built-in back-up
systems for emergency failures. A second shortcoming is the lack of an
information feedback system. If a switch on the operating console activates
a pump, there is no return loop which indicates to the operator that the
pump has in fact been activated and is working.
FLOW MEASUREMENT
Differential Measuring Devices and Instruments
Devices which measure flow and are used with differential measuring
instruments are all descendants of the Venturi tube and are considered pri-
mary devices. Most of the devices require very little head and can handle
flows which contain suspended solids. Larger differential (high-head
recovery) devices, such as the Dall tube, amplify a small, purely static
change in head to a value which can be conveniently measured with secondary
instruments. The high-head recovery, Venturi-type devices are not applicable
to "dirty" fluids (high solids content) except in conjunction with a purging
system. Other exceptions are the flow nozzle and the Lo-Loss tube.
Orifice plates were originally developed for use on gas flows, but have
been applied for use in the masurement of water which contains little or no
solids in suspension.
In general, wastewater can be successfully metered with the long- and
short-type Venturi tube, flow nozzle, and Lo-Loss tube. It must be realized
that an orifice that is too small produces large permanent pressure drops
and is uneconomical. On the other hand, a too-large orifice measurement can
be affected by inlet flow disturbances. The choice of device has to be care-
fully considered.
Secondary Instrument System
These instruments measure the differential produced by the primary
devices and convert the result into a signal for transmission or into a
motion for indication recording or totalization. These instruments include
mercury manometer, diaphragm meter, and various types of force-balance and
motion-balance pneumatic and electronic transmitters.
Other Flow Metering Devices
• Magnetic devices utilize Faraday's Law to measure flow in a
magnetic field. With a.steady magnetic field, the volume of flow
G-2
-------
7046
rate is directly proportional to the generated voltage; a voltmeter
calibrated in volume flow units is then read for the flow measure-
ment. The basic advantages: it has no head loss; it handles solids
in suspension; it has no liquid connections; and it has an electronic
output ready for in-plant transmission.
• Propeller meters utilize the velocity head and convert it into
mechanical power which is linear and translatable into velocity.
This type of system is useful where frequent totalization readings
are necessary.
• Open Channel Devices -
Weirs are of two basic types: rectangular and V-notch. In weir
measurement water abruptly flows through a precise cross section.
The nappe, or profile of water over the weir, must be completely
aerated in order to have precise flow measurement with a minimum
head loss.
Flumes , a modification of the basic weir concept, are designed
primarily to reduce head loss that occurs in weirs. This is
accomplished by having the sides of the channel vary gradually
to the desired cross section.
Open-channel flow nozzle is a combination of flume and weir;
this device can handle solids effectively but does not have the
head recovery characteristic of the in-line flume.
In general, the flow-through of a weir- or flume-type device is a
function of fluid level. The three basic devices for measuring this level
are float-and-cable, the in-flume float, and the bubble tube.
In determining if the type of measuring device is suitable for the
location in the treatment system, the following should be considered:
• Probable flow range
• Acceptable head loss
• Required accuracy
• Fouling ability of wastewater
The diversity of instruments for measuring the various parameters
precludes their individual description in a broad overview. The level of
sophistication of these instruments is rapidly increasing. Devices which
are available and are used for pressure, level, temperature, and analytical
measurements consist of:
Pressure
• Bourdon tube
• Spiral and helical elements
G-3
-------
7046
• Bellows and diaphragm elements
• Wire strain gauges
Level
• Bubble tube
• Diaphragm box
Temperature
• Mechanical (filled thermal) system
• Electrical systems
Analytical Measurement
Type of Measurement
• pH; oxidation-reduction
potential (OKP) (although
many ions can be measured
with selective ion
electrodes)
• Residual chlorine; DO
• Turbidity; color
• Conductivity
Type of Electrical Signal
Voltage or amperage
Amperage or resistance
Resistance
For additional information, see:
Instrumentation and Control in
Water Supply and Wastewater
Disposal by Russell H. Babcock,
P.E. ;
Introduction to Chemical Process
Control by Daniel D.
Perlmutter;
Ch. 19, ASCE Treatment Plant
Design;
Ch. 11, Operation of Wastewater
Treatment Plants, EPA.
G-4
-------
H
-------
MAINTENANCE
DATA SYSTEM
-------
Appendix H
MAINTENANCE DATA
This section of the manual describes the basic components of a main-
tenance system. It describes the type of filing system which could be
employed for maintenance data, how to set up such a filing system, and the
type of information it should contain.
By comparing the maintenance records at the treatment plant with this
guide and manufacturer's maintenance schedule, the plant's maintenance pro-
gram can be evaluated.
It is imperative that a record be kept of the service requirements of
every piece of major equipment in the plant and when and how frequently
service is required. Therefore, a system is needed to keep a complete record
of maintenance requirements. Such a system should provide a permanent record
of all maintenance work together with the advanced scheduling of preventive
maintenance for an entire year. The system should also provide the maintenance
work schedule for any given day. To be efficient, the system should contain
the following five files:
(1) preventive maintenance records
(2) the preventive maintenance schedule for each piece of
equipment
(3) specifications on each major piece of equipment, the
supplier, and where spart parts can be purchased,
(4) spare parts inventory, and
(5) instructions for operation and maintenance of each item
of major equipment.
As a first step in setting up any maintenance record system, each struc-
ture and each major piece of equipment should be assigned a file number. A
simple means of doing this is assigning each area or each structure within a
treatment plant a block of 1000 numbers; and each equipment item in each area
or structure requiring maintenance can be assigned an individual number within
the block of 1000. Therefore, sufficient open numbers remain to provide for
any additional equipment which may be required within that area or structure
in the future. The assigned numbers will serve to identify each item of
equipment in all of the plant records described above and should also be used
to catalog spare parts.
The file of preventive maintenance requirements mentioned in Item 1
above should contain one sheet for each item of plant property which
requires periodic attention or maintenance, filed numerically. Listed
thereon should be all pertinent requirements with respect to periodic
H-l
-------
maintenance including frequency, number of men required, and the estimated
time of performance. These sheets are to be filed numerically as recommended
above and maintained as a reference file.
The file for preventive maintenance scheduling as mentioned in Item 2
above should show the equipment number and the key information given on the
preventive maintenance sheet, together with a specific day for the performance
of each item of work. Space should be provided on each equipment card for the
operator to know the work items performed and the date of performance. A
systematic means of pulling these cards on the dates on which maintenance
work is required should be devised.
The equipment data file mentioned in Item 3 above should contain cards
with complete nameplate data for each item of equipment. These cards may
also be used to show the type of lubricant required, together with the nature
of any special service requirement. The cards should also be filed numeric-
ally in accordance with the recommended system.
The operation and maintenance instruction file mentioned in Item 4
above should contain information relating to maintenance, operation, and
servicing of each item of equipment. This information should be filed numer-
ically in accordance with the recommended system. Specifically, the file
should contain all maintenance and operation manuals furnished by equipment
manufacturers, parts lists, dimension drawings, and other informative
literature.
In order to maintain an effective maintenance program it is recommended
that the maintenance record system be kept up to date faithfully and consist-
ently. Service requirements should be modified as equipment ages and flow
rates increase. All modifications to major plant equipment should be
recorded in the maintenance record system.
A complete set of the as-built drawings of the wastewater treatment plant
should be available for the ready use of the plant operators. The plant
operators should record on these plans all changes that are made in the
plant piping, equipment, and electrical circuitry. The original drawings
of the treatment plant should be updated at least yearly in accordance with
the changes made on site.
For additional information, see:
Ch. 11, Operation of Wastewater
Treatment Plants, EPA.
H-2
-------
REFERENCE
-------
REFERENCES
-------
Appendix J
REFERENCES
1. Advanced Wastewater Treatment Seminar, Session I to III and
Section IV, October 1970.
2. 'Aeration Plants in Florida," ASCE Journal of ganitary Engineering,
Vol. 88, SAG, November 1971.
3. Agardy, F.J., and M.L. Kiado, Effects of Refrigerated Storage on the
Characteristics of Waste, 21st Industrial Waste Conference, Purdue
University, 3-5 May 1966.
4. Babcock, Russel H., Instrumentation and Control in Water Supply and
Wastewater Disposal, R.H. Donnelley Corp., 1968.
5. Gulp, Russell and Gordon L., Advanced Wastewater Treatment, Van
Nostrand Reinhold Environmental Engineering Series, 1971.
6. Eckenfelder, W.W., and D.J. O'Connor, Biological Waste Treatment,
Pergamon Press, 1961.
7. Fair, Gordon M., John Geyer, Water Supply and Wastewater Disposal,
John Wiley & Sons, 4th edition, 1961.
8. Fair, Gordon M., John Geyer, and Daniel A. Okum, Advanced Waste
Treatment, Research Series, AWTR-2 to 12, 1962-1964^
9. "Field Evaluation of the Performance of Extended Aeration Plant,"
WPCF, Vol. 41, July 1969, p. 1299.
10. Imhoff, Karl, and Gordon M. Fair, Sewage Treatment, John Wiley &
Sons, 2nd edition, 1956.
11. Operation of Wastewater Treatment Plants, A Field Study Training
Program, Environmental Protection Agency, Office of Water Programs,
Division of Manpower and Training, 1971.
12. Perlmulter, Daniel D., Introduction to Chemical Process Control,
John Wiley & Sons, 1965~
13. Rich, Linvil G., Unit Operations of Sanitary Engineering, John Wiley
& Sons, 1961.
14. Rich, Linvil G., Unit Process of Sanitary Engineering, John Wiley &
Sons (to be published 1972).
J-l
-------
15. Sawyer, Clair, "Final Clarifiers and Clarifier Mechanisms,"
ASCE STD, MIT, 1962.
16. "Sewage Treatment Plant Design," ASCE Manual of Engineering Practice,
No. 36, WPCF Manual of Practice No. 8, 1959.
17. Short Course - Theory and Design of Advanced Waste Treatment
Processes, University of California Extension, Berkeley, Calif., 1971.
18. Standard Methods for the Examination of Water and Wastewater, 13th
edition, APHA, AWWA, WPCF, 1971.
19. Steel, Ernest W., Water Supply and Sewage, McGraw-Hill, 4th edition,
1960.
20. Waste Heat Utilization in Wastewater Treatment, URS 7032, URS Research
Co., San Mateo, Calif., (to be published 1972).
21. Waste Water Plant Operators Manual, Coordinating Council for Occupational
Education, State of Washington, Division of Vocational Education.
22. Wastewater Treatment Plant Operator Training Course Two, WPCF No. 14,
1967.
J-2
-------
GLOSSARY
-------
GLOSSARY
-------
Appendix K
GLOSSARY
The terminology used in the glossary of this manual reflects particular
meanings of those words and definitions which clarify the basic informa-
tion compiled from the various texts, journals and technical papers used.
BIOCHEMICAL
OXYGEN
DEMAND
(BOD)
BIOLOGICAL
OXIDATION
BY-PASS
CHLORINE
CONTACT
CHAMBER
CHLORINE
DEMAND
COMBINED
AVAILABLE
RESIDUAL
CHLORINE
The quantity of oxygen used in the biochemical oxidation
of organic matter in a specified time, at a specified
temperature, and under specified conditions. It is
not related to the oxygen requirements in chemical
combustion, being determined entirely by the availa-.
bility of the material as biological food and by the
amount of oxygen utilized by the microorganisms
during oxidation.
The process whereby living organisms in the presence
of oxygen convert the organic matter contained in
wastewater into a more stable or a mineral form.
A pipe or conduit which permits wastewater to be
moved around a wastewater treatment plant or any unit
of the plant. This is usually found in plants which
receive combined flow or high infiltration rates
and is utilized to prevent flooding of units, or in
case of shutdown for repair work, flow can be moved
to parallel units.
A detention basin where chlorine which has been dif-
fused through the treated effluent is being held a
required time to provide the necessary disinfection.
The difference between the amount of chlorine added to
the wastewater and the amount of residual chlorine
remaining at the end of a specific contact time. The
chlorine demand for given water varies with the amount
of chlorine applied, time of contact, temperature,
pH, nature and amount of impurities in the water.
That portion of the total residual chlorine remaining
in water or wastewater at the end of a specified
contact period which will react chemically and
biologically as chloramines, or organic chloramines.
K-l
-------
7046
COMBINED
RESIDUAL
CHLORINATION
The application of chlorine to water, wastewater, or
industrial wastes in an amount to produce directly
or through the distribution of ammonia, or of cer-
tain organic nitrogenous compounds, a combined
chlorine residual.
COMBINED
SEWER
SYSTEM
A transport system which carries both sanitary
wastewater and storm or surface water runoff.
DENITRI-
FICATION
EFFLUENT
ENDOGENOUS
RESPIRATION
FOOD
TO
MICROORGANISM
RATIO
HYDRAULIC
LOADING
INFILTRATION
INFLUENT
MIXED
LIQUOR
Chemically-bound oxygen in the form of either nitrates
or nitrites is stripped away for use by microorganisms
This produces nitrogen gas which can bring up floe in
the final sedimentation process. It is an effective
method of removing nitrogen from wastewater.
Wastewater or liquid - raw, partially or completely
treated; flowing from a basin, treatment process,
or treatment plant.
An auto-oxidation of cellular material that takes
pla'ce in the absence of assimilable organic material
to furnish energy required for the replacement of
worn-out components of protoplasm.
An aeration tank loading parameter. Food may be
expressed in pounds of suspended solids, COD,
or BOD added per day to the aeration tank, and
microorganisms may be expressed as mixed liquor
suspended solids (MLSS) or mixed liquor volatile
suspended solids (MLVSS) in the aeration tank. The
flow (volume per unit time) applied to the surface
area of the clarification or biological reactor
units (where applicable).
The flow (volume per unit time) applied to the
surface area of the clarification or biological
reactor units (where applicable),
Groundwater that seeps into pipes through cracks,
joints, or breaks.
Wastewater or other liquid - raw or partially treated;
flowing into a reservoir, basin, treatment process
or treatment plant.
A mixture of activated sludge and wastewater under-
going activated sludge treatment in the aeration tank.
K-2
-------
7046
ORGANIC
LOADING
OVERFLOW
RATE
OXYGEN
UPTAKE
RATE
POSTCHLORINATION
PRECHLORINATION
RAW SLUDGE
RECIRCULATION
RATE
SANITARY
SEWER
SYSTEM
SLOUGHINGS
SLUDGE
AGE
Pounds of BOD applied per day to a biological reactor
One of the criteria for the design of settling tanks
in treatment plants; expressed in gallons per day
per sq ft of surface area in the settling tank.
The amount of oxygen being utilized by an activated
sludge system during a specific time period.
Application of chlorine to the final treated wastewater
or effluent following plant treatment.
Chlorination at the headworks of the plant; influent
chlorination prior to plant treatment.
Settled sludge promptly removed from sedimentation
tanks before decomposition has much advanced. Frequently
referred to as undigested sludge.
The rate of return of part of the effluent from a
treatment process to the incoming flow.
A sewer intended to carry wastewater from homes,
businesses, and industries. Storm water runoff
sometimes is collected and transported in a separate
system of pipes.
Trickling filter slimes that have been washed off
the filter media. They are generally quite high in
BOD and will degrade effluent quality unless removed.
In the activated sludge process, a measure of the
length of time a particle of suspended solids has been
undergoing aeration expressed in days. It is usually
computed by dividing the weight of the suspended
solids in the aeration tank by the daily addition of
new suspended solids having their origin' in the raw
waste.
SLUDGE
DENSITY
INDEX
A term also used in the expression of settling
characteristics of activated sludge 100/S.V.I.
K-3
-------
7046
SLUDGE
VOLUME
INDEX
(SVI)
SUSPENDED
SOLIDS
(SS)
WASTED
SLUDQS
WET
WELL
A numerical expression of the settling characteristics
of activated sludge. The ratio of the volume in
milliliters of sludge settled from a 1000 ml sample
in 30 minutes to the concentration of mixed liquor in
milligrams per liter multiplied by 1,000.
Solids that either, float on the surface of, or are in
suspension in, water, wastewater, or other liquids,
and which are largely removable by laboratory filtering.
The portion of settled solids from the final clarifier
removed from the wastewater treatment processes to
the solids' handling facilities for ultimate disposal.
A compartment in which a liquid is collected and held
for flow equalization and then pumped (by systems'
pumps for transmission through the plant).
K-4
------- |