&EPA
             United States
             Environmental Protection
             Agency
             Office of Water
             Program Operations (WH-547)
             Washington, DC 20460
December 1973
430/9-74-008
             Water
Start-Up of Municipal
Wastewater Treatment
Facilities
                                 MO-8

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                              NOTES

To order this publication, MO-8, "Start-up of Municipal  Wastewater Treatment
Facilities", write to:

                    GENERAL SERVICES ADMINISTRATION (8BRC)
                    CENTRALIZED MAILING LIST SERVICES
                    BUILDING 41, DENVER FEDERAL CENTER
                    DENVER, COLORADO  80225

Please indicate the MO  number and title of publication.

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              START-UP
                 OF
        MUNICIPAL WASTEWATER
        TREATMENT FACILITIES
    MUNICIPAL OPERATIONS BRANCH
 OFFICE OF WATER PROGRAM OPERATIONS
U. S. ENVIRONMENTAL PROTECTION AGENCY
        WASHINGTON, D, C. 20460
        CONTRACT NO. 68-01-0341
           DECEMBER 1973

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                   EPA Review Notice

This manual is  presented  as helpful  guidance and source
material only; it is not  a regulatory document. Mention of
trade names or commercial products does not constitute EPA
endorsement or recommendation for use.
                               11

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                                     ABSTRACT

This manual provides guidance for putting into initial operation a new municipal wastewater
treatment plant, a new addition to an existing treatment plant, or a change in the mode of a
treatment plant's operation. Proper operation of the treatment  plant or process will ensure
that the wastewater is treated in compliance  with the specific conditions and limitations
established for each treatment facility.

Information is  provided  on preparing  for actual treatment plant start-up.  Preparation for
start-up includes: staffing the plant, developing standard operating procedures, conducting
dry- and wet-run testing of equipment, providing  on-site operator  training, conducting
safety training, and establishing procedures when construction is continuing during start-up.

This manual describes start-up procedures for some of the more common pretreatment and
primary treatment units; for the specific secondary treatment processes of activated sludge,
trickling filters, stabilization ponds and aerated lagoons; and for sludge  handling units and
the anaerobic digestion process. The start-up procedures for advanced wastewater treatment
units and processes are not within the scope of this manual

References  are  provided  for  additional  information on administrative  and  process
considerations; a glossary of pertinent wastewater terms is also included.

This  report was submitted  in  fulfillment  of  Contract Number  68-01-0341 under  the
sponsorship of the Municipal Operations Branch, Office of Water Programs Operations, U. S.
Environmental  Protection Agency.
                                           in

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                           TABLE OF CONTENTS

SECTION                                                             PAGE

   I   INTRODUCTION                                                    1

  II  ' PREPARATION FOR START-UP                                       3
            Staffing  	,  ;	6
            Standard Operating Procedures   	8
            Site Meetings	10
            Inventory of Equipment, Manuals, Tools and Consumables	13
            On-Site Operator Start-Up Training  	16
            Safety  	17
            Construction Continuing During Start-Up	19

 III   START-UP OF THE PRETREATMENT, PRIMARY TREATMENT,
      AND CHLORINATION FACILITIES          '                        .   21
            Screens	  21
            Shredding Devices	22
            Grit Chambers  . . .	23
            Flotation Units	25
            SettlingTanks	26
            Chlorination	28
            Summary	29

 IV   START-UP OF SECONDARY FACILITIES                               31
            Activated Sludge	31
            Trickling Filters  	."	49
            Stabilization Ponds and Aerated Lagoons  	53

  V   START-UP OF THE SLUDGE HANDLING FACILITIES                    57
            Anaerobic Digestion	57
            Sludge Conditioning	72
            Sludge Dewatering	74
            Disposal  	77

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                        TABLE OF CONTENTS
                             (Continued)

SECTION                                                       PAGE

 VI   APPENDICES                                                 79
           A     Associated EPA Programs  	81
           B     Glossary	83

VII   ACKNOWLEDGEMENTS                                         87

VIII   REFERENCES                                                89
                                 VI

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                           FIGURES

NUMBER                                                   PAGE

  1   START-UP TIMETABLE OF EVENTS	4
  2   SAMPLE PRE-START-UP INSPECTION RECORD	12
  3   SEQUENTIAL MECHANISM OF ANAEROBIC
     SLUDGE DIGESTION	 59
                              VE

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                         LIST OF TABLES

NUMBER                                                    PAGE

  1  MODIFICATIONS OF THE ACTIVATED SLUDGE PROCESS	33
  2  INHIBITORY CONCENTRATIONS OF ALKALI AND
     ALKALINE-EARTH CATIONS	65
                               Vlll

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                                     SECTION I
                                  INTRODUCTION

The primary function of municipal wastewater treatment facilities is to collect and treat
municipal wastewaters so as to attain the national "... goal of water quality which provides
for  the  protection  and  propagation  of fish,  shellfish,  and  wildlife,  and provides for
recreation in and on the water." The Federal Water Pollution Control Act Amendments of
19_72 stipulate that this function is to be accomplished by publicly owned treatment works
in a consistent and reliable manner so as to meet effluent  limitations based upon secondary
treatment or any more stringent applicable limitations, by July 1,1977, and so as to employ
the best practicable waste treatment technology by July 1, 1983. The specific conditions
and limitations will be identified in a permit issued to each point source discharge under the
"National Pollutant Discharge Elimination System" established by the Act.

Since the discharge of pollutants in excess  of the effluent limitations defined in the plant's
discharge permit is prohibited by the Act, municipal wastewater treatment plants, from the
day of initial operation, must begin to effectively increase the degree of treatment  of the
wastewater. This manual has been prepared to     in the  accomplishment of this objective.

Start-up can be defined as a series of events that lead to  a stabilized, routinely controlled
plant, process, or unit. The manual provides considerations on preparations prior to start-up,
starting up the pretreatmentj primary  treatment and chlorination facilities, and techniques
and considerations  on starting up secondary  treatment processes and sludge handling
processes and units.

The manual is  presented in four major  sections. The first major section, Preparation for
Start-Up, applies to all facilities regardless of type or size. It further applies whether starting
up a completely new wastewater treatment plant or starting up a new process  or unit that
has been added to an existing wastewater treatment plant.

The following section, Start-Up of the Pretreatment,  Primary Treatment, and Chlorination
Facilities, gives  considerations for starting up  some of  the  more common physical and
chemical units involved in wastewater treatment plants.

Section IV, Start-Up of  the Secondary Facilities,  gives considerations and techniques for
starting  up the biological processes  based upon  parameters involved  in the  design and
recognized techniques used for start-up.

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The  fourth  major  section,  Start-Up  of the  Sludge  Handling  Facilities,  provides
considerations for start-up of the more common sludge handling units and considerations
and techniques for starting up an anaerobic digester based upon the design parameters and
recognized techniques used for start-up.

The manual should be used by anyone involved with the start-up of a waste water treatment
plant, process, or unit. It is intended to be a useful source document for persons preparing
start-up recommendations for the start-up section of the plant's Operation and Maintenance
Manual. The manual is also intended to provide considerations and techniques for starting
up a new plant, process, or unit, or restarting processes or units. Persons  using the manual
should exclude only  the particular units or processes that the facility does not have;
however,  Section  II, Preparation  for Start-Up,  is general  and broad  enough  to provide
information on starting up an entire facility or only a particular unit.

The manual further can be used as a general description or reference to plant operations and
functions.

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                                     SECTION H
                           PREPARATION FOR START-UP

This section deals with considerations for the administrative and operational procedures that
should be followed before start-up. Following this guidance will eliminate many problems
and  the potential for  problems often  associated with start-up. The considerations can be
used equally as well by experienced or nonexperienced supervisors in their preparation for
start-up.

The  following is a list of  the  topics and activities contained in this section. They are
presented in a sequence that should  lead to a successful start-up if proper consideration is
given to the guidance discussed in this section.  Figure No. 1, Start-Up Timetable of Events,
is an illustration of the following topics and activities. Although it is for a large plant, it can
be reduced or enlarged to correspond to any size or type of plant, process, or unit.

       1.     Employ Treatment Plant Supervisor who should:
              A.      Develop a working relationship with the contractor's project
                      engineer and equipment suppliers.
              B.      Study construction schedules and plant layouts.
              C.      Initiate start-up  planning and scheduling.

       2.     Employ assistant treatment plant supervisor, chief operator, chemist,
              and/or other key plant personnel who should:
              A.      Study plant layouts.
              B.      Study their individual responsibilities and activities.
              C.      Assist  the  Treatment  Plant Supervisor  with  start-up
                      preparations.

       3.     Develop Standard Operating Procedures (SOP) to include:
              A.      Shift schedules.
              B.      Laboratory sampling and testing schedules.
              C.      Plant record keeping procedures.
              D.      Areas of responsibility.

       4.     Employ  plant  operators,   mechanics and  electricians  meeting
              qualifications based on the Environmental Protection Agency and
              State Regulatory Agency criteria.

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                       EMPLOYMENT OF OTHER
                         PLANT PERSONNEL
                         	30 DAYS
                                                               INVENTORY AND GATHERING
                                                               OF EQUIPMENT, MANUALS,
                                                               TOOLS, AND CONSUMABLES
                                                                      gl DAYS
                                                                                               fe8
                                                                               Z<_1
                                                                               UJ^O.
                                                                               >zz
                                                                               z<(-
                                               E-JUI
                                               >~a—l
                                               co  a,
                                               z>>x
                                               OliJO
                                               uxu
                                                            FIGURE NO. 1

                                                    START-UP TIMETABLE OF EVENTS

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 5.      Employ custodial, clerical and/ or individual laboratory personnel.

 6.      Modify  SOP for plant  start-up  and minimize  modifications from
        normal operating procedures.

 7.      Hold  initial  site meeting  to coordinate  start-up schedule  with
        construction schedule.

 8.      Inventory and gather equipment manuals, tools, and consumables
        following the plant operation and  maintenance  manual and the
        equipment manufacturer's recommendations.

 9.      Conduct Dry-Run Inspection to ensure that:
        A.     The installation of the equipment is checked and corrected if
               necessary.
        B.  ,  'The  construction  of  the plant structures is checked  and
               corrected if necessary.

10.      Conduct On-Site Dry-Run Operator Training in:
        A.     The operation and maintenance of equipment and tools.
        B.     The laboratory sampling and testing procedures.
        C.     The "plant layout and start-up responsibilities.
        D.     The plant safety.

11.      Conduct Wet-Run Inspection of:
        A.     The equipment for proper operation.
        B.     The piping and valves for leaks.
        C.     The laboratory testing equipment.
        D.     The monitoring and flow measuring instruments.

12.      Conduct On-Site Wet-Run Operator Training
        A.     Instruct personnel in:
               (1)    The operation of the equipment under load.
               (2)    The capabilities and limitations of the equipment.
        B.    ' Conduct tours of similar plants.
        C.     Institute buddy training with other plants in the area.
        D.     Institute education from Federal and State training programs.

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      13.      Hold Start-Up Planning Site Meeting to:
               A.      Review start-up sequence and activities.
               B.      Discuss responsibilities of all personnel and involved parties.
               C.      List persons to be present during start-up.
               D.      List persons to remain on call during start-up.
               E.      Discuss emergency action procedures.

      14.      On start-up day, place start-up procedures into action.

The start-up of any municipal treatment facility is a complex operation requiring careful
planning, effective coordination, and detailed preparation to maximize the treatment plant's
efficiency and to  minimize problems. The information provided in this section should be
sufficiently general to apply to any wastewater treatment facility process or unit regardless
of type and size. The details of any start-up procedure will, of course, have to be tailored to
a specific facility, process, or unit. Giving consideration to the guidance contained in this
section will help ensure that no important activities are overlooked  during preparation for
start-up. This section  also contains considerations for organizing productive site meetings
prior to start-up, providing effective on-site  operator start-up training,  and  minimizing
problems that might arise  when  plant construction is continuing while a portion  of the
facility is being started up.

STAFFING
A  major consideration  before  start-up is  the selection  of  personnel  to operate  the
wastewater treatment facility. To aid in the selection of personnel, the U. S. Environmental
Protection Agency (EPA) has developed  two  manuals entitled "Estimating Staffing for
Municipal Wastewater Treatment Facilities,"  Contract No. 68-01-0328, and "Estimating
Costs and Manpower  Requirements  for Conventional Wastewater  Treatment  Facilities,"
Contract No. 14-12-462.  These manuals discuss the skills required by the  plant personnel,
plant staff  organization,  and  the means  to  determine the  necessary number of  plant
personnel. One of the most thorough methods for determining the necessary  number of
plant personnel presented in the  staffing manuals is by task analysis. Briefly, this method
consists  of making an analysis  of the tasks  or jobs that are to  be performed in  the
wastewater  treatment  plant and  then each task or job is assigned a skill requirement. The
analysis provides information on the skills and qualifications necessary to perform each task.

The supervisor of the treatment system should  be selected well in advance of plant start-up
to  observe  construction   of  the facility,  become  familiar with the plant  layout and
equipment,  and employ and organize the plant personnel. (See Figure  No.  1, Page 4) The

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supervisor  should review  with the project engineer: the engineering drawings,  process
concepts, the O & M Manual, and equipment layout. In addition, the supervisor of the
wastewater treatment plant:

       1.     Has  the  responsibility  for  the administration,  operation  and
              maintenance of the entire plant.

       2,     Exercises direct authority over all plant functions.

       3.     Develops and initiates changes in plans and procedures of operation.

       4.     Organizes  and   directs  operating personnel's  activities  and
              responsibilities.

       5.     Inspects plant regularly.

       6.     Analyzes and evaluates plant performance.

       7.     Controls and recommends expenditure of funds.

       8.     Maintains  effective channel  of  communications and relationships
              with employees, public officials, and the general public.

The supervisor should have invested in him the authority to speak for the owner. However,
since  the supervisor will  have  no direct authority over the contractor or manufacturer's
representative, it is very important that he establish  good relations with these persons in
order to leam as much as possible about the plant and its equipment.

If possible, the plant  operators should be employed  well before start-up in order that they
may  participate  in on-site training. The operator may be  called upon to perform any
combination of tasks for controlling operation of the plant. These tasks may include:

       1.     Controlling flow and processing of wastewater and sludge.

       2.     Monitoring gages, meters, and control panels.

       3.     Analyzing  meter,  gage, and control readings and test results to
              determine process requirements.

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       4     Operating pumps, gates, valves and engines to control and adjust flow
              and treatment processes.

       5.     Collecting samples and performing laboratory tests,

       6.     Performing maintenance on equipment.

       7.     Making operating decisions in the absence of supervisory personnel.

Many states require that the operators of a sewage treatment plant be certified by the state.
The state  certifies that the  operator is familiar  with sewage treatment  processes and
operations. As many  certified operators as needed should be employed to ensure that the
above considerations and the state requirements are met.

In  smaller  wastewater treatment  plants, the  operators may  perform mechanical and
electrical maintenance, and laboratory sampling and testing. If the plant staff is divided into
individual positions of operators, mechanics, electricians, and laboratory personnel, these
positions should also  be filled before start-up and  the personnel properly trained in their
respective duties and responsibilities and familiarized with the plant layout and equipment.
For the purpose of this manual, these individual positions  will be termed as operators.

All other staff positions such as custodial and clerical should also be filled before start-up.

STANDARD OPERATING PROCEDURES
Developing  proper  operating procedures during start-up will help eliminate many  of the
problems with processes and equipment that plague poorly operated wastewater treatment
plants. By using the plant's 0 & M Manual,  the supervisor, with other key plant personnel
and the project  engineer, should develop the standard operating procedures. The  standard
operating procedures should include:

       1.     Each shift schedule and procedures for transferring plant operations
              from one shift to another:
              A.     The number of men required for each shift.
              B.     The operator's individual responsibilities.
              C.     The schedule of daily and nondaily     to be performed.

       2.     The schedule of laboratory sampling and testing,

       3.     The procedure for recording:

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              A,     The plant operations and maintenance activities,
              B.     The maintenance schedules.

       4.     The procedures for changing the operation of the facilities,

       5.     The plant staff organization.

The standard operating procedure  should be reviewed and revised periodically by the
wastewater  treatment plant management. To aid in developing the standard operating
procedures,  the  EPA is presently developing a "Guide for Developing Standard Operating
Job Procedures for Wastewater Treatment Plants," Grant No. 900253.

During start-up,  the standard operating procedure may have to be modified. The supervisor
should try to arrange the start-up shift schedule as close to the normal operating schedule as
possible. Key personnel  such as  the shift foreman,  project engineer, and start-up experts
may be called upon to work more than one shift. Extra personnel may also be required for
one or more shifts due to the increased work load  that accompanies start-up. In small plants,
where the maintenance force is available on one shift only, the force should be on 24-hour
call during start-up.

The procedure for. shift  transfer should not have to be modified a great deal for start-up.
The new shift should be -provided  with laboratory test results, process readouts, visual
inspection data,  any control action taken, and any other pertinent data needed to evaluate
the condition of the treatment process.

During start-up, the supervisors and shift foremen should meet with their counterparts to
review the shift  log and discuss any unusual conditions or problems. They should review all.
new  operations and maintenance forms during start-up to  ensure the  forms are being
completed correctly by  the treatment plant personnel. The plant supervisor, acting as the
start-up  coordinator, should see that all start-up information  or special instructions are
properly transferred from one shift to another.

The standard operating procedures should detail the schedule of laboratory sampling and
testing. These" procedures should be introduced  to  the  operating personnel by the plant
chemist, lab technician, or  chief operator. The operator's performance in  sampling and
testing should be reviewed  in order  to prevent any bad practices from developing into
routine operational procedure. The importance of accurate sanipEng and testing as a process
control tool and its importance  during start-up  should  be explained to all  the operating
personnel. The schedule  of laboratory sampling and testing should provide for: (1) the type

                                          9

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of testing, (2) the time of testing, (3) the quantity of samples, (4) the point from where the
sample is to be obtained, if not a composite sample, and (5) the frequency of sampling and
testing. During start-up, some tests may be run more often than normal, and sampling points
may have to be changed. The supervisor should see that the start-up schedule for sampling
and testing is written and reviewed with the key plant personnel. The EPA has prepared a
manual  entitled  "Estimating  Laboratory  Needs  for  Municipal  Wastewater Treatment
Facilities," EPA430/9-74-002, to provide information  on what an individual  wastewater
treatment plant's laboratory needs are.

Proper plant records during and after start-up are essential to ensure that the treatment
plant will operate  efficiently. As mentioned  previously, the records should include the
laboratory test results, any control  action taken, and  any specific tasks performed. All
unusual  conditions observed  should  be recorded for future reference. Figure No.  7 in
"Considerations for Preparation of Operation and Maintenance Manuals," EPA-430/974-001
is a sample  of a portion of the standard operating procedure, the daily operating log. The
supervisor should supplement the daily  log with the number of men on each shift and their
responsibilities and duties, and provide a schedule for nondaily tasks to be performed.

SITE MEETINGS
The  objectives of start-up  site  meetings are  to  produce cooperation and understanding
between the different parties involved with start-up by providing a  means to: (1) schedule
events, (2) inform all affected parties of any action to be taken, and  (3) discuss and solve
problems and conflicts  of  interest. (See Figure  1, Page 4) The major site meetings are
referred to as the:

       1.     Initial
       2.     Dry-Run Inspection
       3.     Wet-Run Inspection
       4,     Start-Up Planning
       5.     Start-Up Day

Initial Site Meetings
The  initial site meetings between the plant superintendent, contractor's project engineer,
and the  equipment supplier are to coordinate the start-up schedule with  the construction
schedule.

The supervisor should request that he be allowed to observe all installation, inspection, and
pretesting of the  plant equipment. This procedure will enhance the supervisor's knowledge
                                        10

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 of the facilities and will also allow him to note any discrepancies he feels should be brought
 to   the  attention of the  contractor's  project  engineer,  equipment  manufacturer's
 representative, or owner as he deems appropriate.

 When construction is well underway, the supervisor should meet with the above persons and
 request that he be allowed to take the treatment plant personnel  through the plant and
 familiarize them with the treatment plant equipment. This tour will require written approval
 from the contractor if  he intends to operate the equipment unless that particular piece of
 equipment  has been turned over to  the  owner  as  being "substantially complete." The
 supervisor should also  request the  equipment manufacturer's  representatives to assist in
 training the plant operators in  the maintenance  and operation of the  equipment. The
 supervisor can then arrange a schedule for the training of the plant operators and testing of
 the plant facilities.                                                   ~"

 Dry-Run Inspection Site Meetings
 The dry-run inspection  site meetings should be attended by the contractor, manufacturer's
- representatives, and the supervisor. The supervisor should record the actions that take place
 in the meeting. A form such as Figure No. 2, Sample Pre-Start-Up Inspection Record, will be
 of help during the inspection of the facilities and can be used as a permanent record for the
 plant's  log book. The supervisor should have a copy of the manufacturer's literature on the
 installation, inspection  and pretesting  of their  equipment. This information will enable the
 supervisor to become more familiar with the  plant equipment and help him to notice any
 deficiencies that are present.

 During these meetings, the supervisor with  the project engineer should see  that the
 manufacturer's representative  checks  the  equipment for  proper mounting, direction  of
 rotation or travel, proper lubrication  with the type of lubricants recorded  and properly
 filed,  clearances,  alignments',  undue  noise  and  vibration, safety devices, and general
 operation. The supervisor and project engineer should see that the contractor removes all
 rags, stones, paper and other debris; that the  piping is inspected for obstructions; that all
 piping and line connections are checked for leaks; that all gates and valves are checked for
 operation and seating; and that all safety chains and guards are in place.

 The supervisor should also see that  all equipment is properly broken in, that all equipment
 not to  be used immediately is properly protected, and that the laboratory-equipment is
 inspected for proper operation and calibration.

 The inspection party should see' that the malfunctions are scheduled for corrective action
 and a time is arranged for the operator's  dry-run training and the wet-run testing of the

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PLANT NAME AND LOCATION
EQUIP.
NO.
1001
1057

















EQUIP.
)ESCRIPT.
COMMINUTOR
RAW SEWAGE
PUMP # 1




GRIT CHAMBER
#1

CONNECTION
OF PIPE
TO RAW
SEWAGE
PUMP #4




DRY RUN TEST AND
CORRECTIVE ACTION
OK
LOOSE MOUNTINGS -
CONTRACTOR WILL COR
RECT BY 1/24/65
IMPELLER CRACKED -
SUPPLIER WILL REPLACE
BY 2/3/65
OK


OK








DATE
1/23

1/23

1/23


1/23


1/23








WET RUN TEST AND
CORRECTIVE ACTION
OK

UNDUE VIBRATION -
SUPPLIER WILL FIX BY
3/3/65


DEAD SPOT -
CONTRACTOR WILL FIX
BY 2/18/65
PRESSURE LEAK -
SUPPLIER WILL REPAIR
BY 2/19/65






DATE
2/17

2/21




2/17


2/17








CERTI-
FIED OK
2/17/65

3/5/65




2/18/65


2,19/65








            FIGURE NO. 2
SAMPLE PRE-START-UP INSPECTION RECORD

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facilities. Note: This manual's section  on on-site operator training will present detailed
considerations of the'operator's training.

INVENTORY OF EQUIPMENT, MANUALS, TOOLS, AND CONSUMABLES
Prior to start-up the following items should be on hand, properly inventoried and stored by
the supervisor and his staff:

       1.      A facility operation and maintenance manual.

       2.      A complete set of as-built drawings.

       3.      Construction specifications.

       4.      An indexed collection of construction photos.

       5.      The manufacturer's  literature on operation  and maintenance of his
              equipment, including parts list, component specifications sheets and
              drawings, and schematic drawings of the components supplied.

     .  6.      Manuals and literature deemed appropriate  for plant operation and
              efficiency. (See the plant's O & M Manual for a partial list,)

       7.   -  Laboratory glassware, equipment,  and chemicals needed in process
              control.

       8.      All  tools  and  equipment   needed  for  plant  operation  and
              maintenance.

       9.      All safety equipment.

      10.      Chemicals needed for process control and operation.

      11.      Spare parts for each  piece of equipment as recommended by manufacturer.

      12.      Grease and oil needed for maintenance and operation of equipment.

The plant's O & M Manual should contain a list of similar items tailored for a specific plant.
Most of these items should be on hand prior to testing the equipment.

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Wet-Run Inspection Site Meetings
The wet-run inspection site meetings generally should occur after the wastewater treatment
plant's owner has accepted the facility or unit as being "substantially complete."

By accepting the facility or unit, the supervisor and his staff will be free to operate the
equipment on their own schedule. The contract document will call for a warranty period
from the contractor and equipment manufacturer and, therefore, the wet-run inspection and
testing should be done as early as possible to  enable corrections to be made promptly and
before actual start-up. If possible, the supervisor should have the equipment manufacturer's
representatives  present during the wet-run inspection.  His  input  will be valuable to the
supervisor and his staff.

The equipment  manufacturer's  instructions should be  followed when inspecting  and
pretesting his equipment. The wet-run inspection should include:

       1.     Checking all piping and valves for leaks.

       2.     Inspecting operation of all gates and valves.

       3.     Inspecting all pumps.

       4.     Operating all mechanical devices under hydraulic load.

       5.     Inspecting chlorination facilities.

       6.     Observing laboratory sampling and testing procedures.

       7.     Checking  all  electronic/pneumatic  instrumentation  for  proper
              operation.

       8.     Inspecting all flow meters, temperature and pressure indicators.

       9.     Inspecting all weir levels and adjusting for start-up.

All deficiencies found during the inspection and testing should be corrected before start-up.
The supervisor and contractor's project engineer should then schedule a start-up planning
site meeting.
                                         14

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Start-Up Planning Site Meeting
The supervisor should inform the persons who are to be present at* the start-up planning site
meeting  of the  date, time,  and location of the meeting. The supervisor should provide
persons present  with the meeting agenda and any topics that they may be called upon to
discuss. The supervisor, acting as  the start-up  coordinator, should  have discussed with his
staff, and  the contractor's project engineer, the procedure for start-up and  incorporated
their comments prior to  the meeting. The site meeting to prepare  plans for plant start-up
should include the contractor's project engineer, the treatment plant owner's representative,
the plant supervisor, start-up consultants, the assistant supervisor, operations supervisor,
maintenance supervisor, chemist,  consultant's construction administrator on the project,
contractor's job superintendent, and any representatives from  manufacturers of key or
unusual treatment units or processes.

At  the meeting the supervisor, again acting as coordinator, should accomplish the following
items:

       1.     Select a tentative start-up date.

       2,     List the persons who should be on hand at start-up.

       8,     Giro the individual responsibilities at start-up,

       4.     Outline the events for start-up,

       5.     State  who will remain on the site during start-up and  who should
              remain on call.

The start-up coordinator should develop a timetable  of events showing all activities from
initial plant start-up to  full operating efficiency.  An illustration of  a Timetable of Events is
shown in Figure No. 1, Page 4.

Start-Up Day Site Meeting
At  the start-up day site meeting, the contractor's project engineer and equipment suppliers
should be  on hand  not only to ensure that the treatment equipment functions correctly but
also to continue training the operating personnel. Any plant activity during start-up such as
sludge pumping and  vacuum filtration, which may not be common to all operating shifts,
should be  observed by the key plant personnel from all shifts. All operator functions should
be  monitored and critiqued  by the supervisor  so that bad practices  are not allowed to
develop  as standard operating procedure.  Maintenance support  from other municipal
divisions and local  repair services for equipment  should be alerted when the plant is ready
for start-up.
                                         15

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ON-SITE OPERATOR START-UP TRAINING
In order to achieve the treatment objectives of the plant, it is necessary to have skilled plant
operators. The supervisor, project engineer, and the appropriate equipment suppliers should
conduct a series of tours through the plant  for the operating  personnel. The purpose of
these tours is to familiarize the personnel with the plant and train them in their operation
and  maintenance  responsibilities. The  tour  party should  be  tailored according to the
operator's experience or responsibilities in order  to keep the group manageable and to
ensure that the training objectives are met. Training should be separated into Dry-Run
Training (without any water or wastewater in the plant) and Wet-Run Training.

The  supervisor  should be responsible for organizing the different groups, instructors and
timetable. Considerations should be given to the fact that  the instructors may be available
for only a  few  days and, therefore, the supervisor should take  steps to organize the
operator's training around the instructor's schedule. An  example of  the operator's training
program may look something like this:

       Tuesday, October 20,1972

       First Group - Primary Clarifies

       1.      N. Royal
       2.      J. Mohr
       3.      W. Roberson

       Instructor - J. Staples (Equipment Supplier, Inc.)
       8:00  -  12:00  -  Operation and maintenance; emergency procedures

       Second Group - Laboratory

       1.      A. Ingram
       2.      J. Ballard
       3.      G. Mills
       4.      O. O'Donnel

       Instructor - C.  West (Chemist)
       8:00  -   12:00  -  Sampling  and  testing;  operation,  calibration and
                     maintenance  of equipment; test  results and  procedures for
                     corrective action; log book
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Dry-Run Training
The operator's dry-run training should provide the operator with instruction in  all the
various unit operations of the treatment plant, in the performance of his duties, and  inform
him of his responsibilities. The supervisor or foreman should have the construction drawings
and  the  plant's Operation and  Maintenance Manual  to assist  in the explanation  of the
operations of the  treatment facility. The  dry-ran training should also familiarize the
operating personnel with the equipment layouts, piping arrangements, remote monitoring
equipment and process control equipment.

The operator should be provided with instruction in the execution of Ms specific duties. If
possible, the operator should be shown by actual demonstration how to perform preventive
maintenance on the various pieces of equipment he  must operate. The importance of
scheduled maintenance to prevent damage to the plant equipment should be emphasized.

Wet-Run Training
The wet-run training will strengthen the operator's understanding of the plant's treatment
processes and will demonstrate  how the equipment functions under hydraulic load. The
operating personnel should also receive instruction in the role each piece of equipment has
in the overall treatment objectives of the wastewater treatment  plant. If  possible, the
supervisor should supplement the on:site training with:

       1.     A tour of similar plants or processes in the area or a pilot plant.

       2.     Buddy training,  in which the  operator is placed in a plant with an
              experienced operator performing the same tasks and having the same
              responsibilities as he will have.

       3.     Short courses offered by the  state, .federal, or local agencies or by
              holding classroom instruction himself.

       NOTE: The  EPA's "Operation of Wastewater Treatment Plants," Technical
              Training Grant No. 5TT1-WP-16-03, is a home study course  but  is
              also a useful reference for classroom training.

SAFETY
Accidents don't just  happen — they are caused, and  during  start-up  the  potential tor
accidents is increased. Some factors contributing to this potential increase are:
                                        17

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        1.      Personnel unfamiliar with equipment and operating procedures,

        2,      Empty tanks and basins.

        3.      Improperly installed equipment.

        4.      Inadequate lighting,  ladder  placement,  handrail  locations  and
               equipment layout.

        5.      Personnel exposed  to electrical and mechanical hazards due to initial
               operating adjustments.

        6.      Personnel  unfamiliar  with proper  chemical handling, including
               chlorine.

        7.      Inadequate tools for repairs.

The wastewater treatment facility should have a safety program underway before start-up.
Safety meetings with the plant personnel should be held routinely to discuss hazards in the
                               i
plant. Some of the hazards within the plant will be exposed  during the operator's tour
through the plant and during the  dry- and wet-run training. Any hazards identified by the
tours and training should be corrected before start-up. Signs, posters,  and physical barriers
should be used to designate hazardous areas of the plant if corrective action is to be delayed.

Some means  of motivating the personnel toward safety should be  established  such as
bonuses,  medallions,  and  time off. Other potential hazards such as  diseases, lifting of
equipment, and burns and cuts should  be dealt with through the operator's training in
safety, first-aid and health.

The  operator's training in  the  handling of  chemicals, especially  clorine, should  be
thoroughly examined before start-up. A trial  run in the connection and the use of the
chlorine facilities should be carefully monitored by the supervisor and a qualified chlorine
expert. The Water Pollution Control Federation's  MOP No. 1, "Safety  in Wastewater
Works," and the Chlorine  Institute's "Chlorine  Manual," 4th Edition, should be used in the
•operator's training in the handling  of chlorine.

The Safety section  of the plant's O & M Manual should contain an in-depth discussion of
safety along with a recommended list of safety equipment for the plant.

                                        18

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The Safety section of the O & M Manual in conjunction with other safety manuals, such as
the Water Pollution Control Federation, MOP No. 1, "Safety in Wastewater Works," should
be thoroughly reviewed with the operators before start-up. The EPA is presently developing
a safety manual entitled "Safety in the Design, Operation and Maintenance of Wastewater
Treatment Works,"  Contract No. 68-01-0324, to  be of  assistance  in developing  and
operating a plant safety program.

Before start-up, all personnel should  have  a complete physical and be immunized against
waterborne diseases. The safety equipment listed in the plant's O & M Manual such as gas
masks, safety  clothing, and first-aid kits should be inventoried and operational.  The local
hospitals and  police and fire departments should be notified of the chemicals that will be
used at the plant and their telephone numbers posted in a conspicuous place.

The accident report forms and the procedures for treating injuries also should be established
prior to start-up.

CONSTRUCTION CONTINUING DURING START-UP
At the start-up planning site meeting, it may be decided that construction of the entire plant
does not  have to be completed before start-up can be initiated. It is not uncommon for
certain construction and equipment  installation to be continuing when the plant or a
portion of the plant is placed  into  operation. Whenever this condition exists, a careful
analysis should be made to ensure that start-up  can, in fact, take place.

The importance of the following recommendations is shown by the following case history:
Recently, a failure of communication and understanding between the contractor and the
plant supervisory staff, in  conjunction with other complications, resulted in the complete
disruption of plant operations. As a result, the waste into the plant was bypassed into the
receiving  waters for a number  of days. The  pollution of the receiving waters  was great
enough to cause pubic officials to forbid public or private use of the water in the area for a
period of some 13 to 14 days. Further study of this situation reveals that it could  have been
avoided if caution had been exercised and the lines of communication had been established
prior to starting up the new facilities. From this study, the following recommendations have
been prepared.

The contractor and equipment suppliers should assure the supervisor and his staff  that there
will be no unannounced interruption of electrical power due to construction schedules, that
all the necessary equipment is installed correctly and operating properly, and that the plant
personnel will not be subjected to any undue safety hazards.
                                        19

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The contractor and  plant supervisor should coordinate all  their activities. They should
develop a timetable of events for their projects and coordinate each other's special  needs
while  construction and  start-up are proceeding  simultaneously.  The  contractor and
supervisor must also anticipate contingencies that might occur. The access roads, hallways,
or steps may be blocked due to  the unloading of materials; parking problems and traffic
problems might arise due to  shifts being changed simultaneously; and storage of supplies
such as paint, gasoline, and chemicals may conflict with access to other supplies.

The supervisor and contractor should define in writing their respective responsibilities for
men, machines, and areas in case  an accident to men, machines, or structures should occur.
For example, if the contractor is having equipment and supplies  delivered to the site, the
agreement  would indicate  where deliveries should  be  made  and stored, thus  avoiding
possible  damage to buried lines or cables from heavy equipment, keeping valves or lines
from being inadvertently  covered, and ensuring access to  certain areas needed both by the
contractor's and supervisor's personnel. A procedure should be included in the agreement to
clarify responsibilities in cases  where problems arise beyond the scope of the agreement.

The contractor and supervisor not only should define their responsibilities  but also should
define who is in charge in their absence. It is important that the person in charge be defined
so as to give guidance and answer questions as required. The areas  where the contractor's or
supervisor's personnel should  not  go should be clearly indicated with  physical barriers and
signs.

Safety is of the utmost importance when construction is continuing during start-up. Hazards
to personnel as well as  the hazards to any biological processes are peatly increased, and the
recommendations in the safety portion of this section should receive added emphasis  under
these  conditions.  Communication  between the  contractor  and  his personnel  and the
supervisor and his  staff is absolutely necessary to help ensure no conflicts of interest will
result  and that personnel will not be subjected to  any undue hazards.
                                         20

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                                    SECTION III
           START-UP OF THE                   PRIMARY TREATMENT,        '   '
                         AND CHLORWATION FACILITIES .

Pretreatment  and  primary treatment  facilities are  the  key to  proper operation  of
conventional secondary treatment processes and sludge handling facilities. These facilities
screen out debris and remove grit, grease, and settleable solids, all of which are harmful to
the biological treatment processes and can damage plant equipment. Although the start-up
of these  facilities is often a "push-button" operation, proper inspection and pretesting of
these units  can eliminate many  problems that occur during the start-up of wastewater
treatment plants. Proper start-up of the  pretreatment,  primary treatment, and chlorination
facilities  will also help ensure an efficient start-up and maximize overall treatment plant
efficiency.

This section, gives consideration  for starting up these  facilities in regard to the overall
wastewater treatment plant objective. The guidance is general enough to apply to any of the
units regardless of any  particular type of unit,  although the guidance does not, nor is it
intended to, replace or dupEeate an individual equipment manufacturer's instructions or
recommendations.  The  manufacturer's  instructions  and  recommendations should  be
consulted whenever installing, inspecting, pretesting, maintaining, or starting his equipment.
It is, assumed that the previous section's considerations concerning preparation for start-up
have been developed.                                             -  ,  .
                    -i S  «*•«*.*                     '    »
Common operating problems and their solutions not discussed in this manual can be found
in the EPA's "Procedural Manual for Evaluating the Performance of Wastewater Treatment
Plants," Contract No. 68-01-0107, and the WPCF's MOP No. 11, "Operation of Wastewater
Treatment Plants." Each  treatment plant's  O  & M Manual should also contain valuable
information to help solve operating problems.

                                        ,         ,   ,
The purpose of the screens is to remove or retain the coarse sewage solids which are likely to
produce  nuisances      create problems  in the operation of pumps, raking mechanisms, or
other mechanical facilities.

The screens are either manually or mechanically cleaned and the debris removed is disposed
of by burial, incineration or, in some cases, by being placed in grinders or shredding devices
and returned to the plant influent. The areas around  the screens should be  cleaned
periodically of any spillage  to help prevent accidents and help eliminate insect and odor
nuisances,                                                            -  "
                                        21

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Inspection and Pretesting
The manually cleaned bar screens should be inspected for proper installation and a schedule
provided for cleaning of the screens during start-up and normal operation.

The mechanically cleaned bar screen should be checked to ensure that it has been installed
properly and according to the equipment manufacturer's instructions, the operating interval
is suitable for start-up conditions, and the drive mechanism has been properly lubricated and
the lubricant type has been recorded and properly filed.

Once the screen mechanism is ready for pretesting, it should be turned through a complete
cycle either by hand or  jogging with electrical power to check for proper clearances and
operation. The overload  switch should be tested,  if possible, to ensure that it will protect
the drive mechanism if jamming  of the screen occurs. The bar screen should then be run
three to four hours to break it in and amperage reading taken and recorded.

Start-Up
During start-up the manually cleaned screens may require frequent attention due to large
amounts of debris that may have accumulated in the collection system. Clogged screens can
cause  sewers to surcharge and may create  septic wastewater in the collection system. This
condition could result in a shock load on the treatment plant when full flow is resumed.
Extra personnel may be needed to help  remove the debris that collects on the screens if an
unusually large quantity is expected.

The mechanically cleaned screens help overcome the problem of screen clogging. However,
the screens may collect  debris which the cleaning  mechanism  is unable to remove and
periodic  checks for proper screen  operation  should be scheduled.  Depending on the
direction of travel of the cleaning mechanism, the screen rakes can become jammed due to
the debris that  may collect at the base of  the screen. Although this occurs infrequently, it
should be especially watched for during start-up. The scraper  mechanism that removes the
debris  from  the rakes should also be  inspected.  If the scraper  does not  clean the rakes
properly, the debris will  be returned to  the wastewater.  The scraper mechanism should  be
adjusted  as soon as possible to correct this problem if it occurs. The screen should also  be
inspected at  frequent intervals  during start-up to see that it is cleaning properly, that  all
alignments are maintained, that all bolts are tight, and that there is no undue vibration.

SHREDDING DEVICES
The comminuting or shredding devices overcome the  problem of disposal of debris  by
cutting up  the materials retained on the bar screens until they can pass through the screen

                                        22

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 openings and flow into the treatment plant. The comminute cuts up the  material fine
 enough  to  prevent it  from damaging the pumps or other mechanical equipment. The
 comminutor helps reduce odors and  other nuisances often associated with bar screens,
 although the solids returned to the wastewater  may produce more  scum  in  anaerobic
 digesters.

 Inspection and Pretesting
 As mentioned previously (under the discussion of the bar screens), shredding devices should
 be installed in accordance with the manufacturer's instructions. The shredding 'devices
 should be inspected for proper clearances, alignment, and proper lubrication. The lubricant
 types should be recorded and properly filed and all required safety alarms and/or overloads
 should be operational.

 After the shredding devices have been inspected for proper installation, they should be
" pretested by hand turning or electrically jogging the shredder through one complete cycle to
 check for proper clearances and alignment.

 The  shredder should then be broken in  for  three or four hours  and  inspected for tight
 mountings, vibration,  overheating,  and undue noise; and an amperage reading taken and
 recorded.

 Start-Up
 During start-up it is important to inspect the comminuting and shredding equipment to help
 protect the unit's cutters. The pre-start-up site meetings should have produced a frequency
 of inspection  during  and  after start-up.  Most units  have       placed in  front of the
 comminutor to catch  rocks and other heavy material. These traps should be checked and
 cleaned  of  all  stones,  sticks, and other unwanted material. The shredding area should be
 kept clean to help prevent accidents.

 GRIT CHAMBERS
 The  function of  the grit chambers is to remove sand, stones, cinders, and "other heavy
 inorganic material. Grit chambeis provide for the early removal of  this material,  thus
 protecting  the  mechanical equipment from abrasive  action; reducing the formation of
 deposits in pipelines, channels and conduits; and reducing the amount of inorganics entering
 biological process units.

 The  gravity type grit chambers are usually rectangular in shape and rely on the velocity of
 the wastewater through the chamber for grit removal.  The flow is usually maintained at
                                        23

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approximately one foot per second by the use of proportional weirs, orifices or flumes. This
velocity  allows the  heavier inorganics to settle out and be removed, either manually or
mechanically, and the less dense organic material to remain suspended.

A similar grit chamber uses  air diff users or impellers to create a controlled velocity spiral roll
in the liquid which allows the heavier inorganics to settle out below the spiral roll and the
organies  to remain suspended. The velocity of  the roll is controlled by the  rate of air
diffusion or by the impellers and the shape of the grit chamber.

Some grit chambers do not rely on velocity control but  rely instead on mechanical means of
removal. One type      an inclined submerged reciprocating rake to resuspend the lighter
organic material from the inorganic materiaL Another type uses the principal of centrifugal
force to separate the materials. Both of these pit chambers separate and classify the settled
materials more effectively than the velocity-controlled grit chambers.

Inspection and Pretesting
The inspection and pretesting of the     chamber will vary according to the mechanical
equipment used.

The inspection of  the  gravity type pit chamber will be  oriented toward  inspecting the
construction of the basin and cheeking the flow control  device for proper installation.

The spiral roll type of grit chamber should be inspected for construction and any debris left
after construction. The driving equipment such as blowers or motors should be inspected for
proper installation, tight mountings, and lubrication.

The mechanical grit chamber should be inspected for proper installation in accordance with
the manufacturer's instructions. The manufacturer's literature should contain an equipment
inspection  checklist. In general, the lubrication should be  checked and  the lubricant type
recorded and properly filed. AH clearances and  alignments should be checked carefully and
the mechanism should  be turned by hand,  or electrically jogged, through one complete
cycle.  The  unit should  then be run for  three to  four hours and inspected  for motor
overheating, safety devices, proper installation  of guards, undue noise and vibration, and
mounting.

Another  part  of the grit  chamber that will require inspection and pretesting is  the grit
removal  mechanism.  The  mechanism should  be inspected for  tight mountings,  proper
lubrication, clearances, and alignment. This mechanism should have a short break-in period
                                        24

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before being placed into operation. Any electric motors  involved should  be inspected,
tested, properly lubricated, and an amperage reading taken and recorded.

Start-Up
During start-up the grit  chambers should be inspected periodically to ensure that the grit
removing mechanism is operating properly.  The frequency of grit removal may have to be
increased during start-up due to possible large accumulation of grit in the collection system.

FLOTATION UNITS
Flotation is a unit operation  which floats  dissolved  and suspended particles to the water
surface where they are removed, either manually or mechanically. The particles are made to
float  by air bubbles that adhere to the particles causing the particles to  float to the water
surface. The flotation units  have also been used as sludge thickeners. (See Section V, Sludge
Conditioning.)

Flotation tanks are classified as air flotation, dissolved-air flotation, and vacuum flotation.
The end result is  the same in any of the units; that  is, the release of air bubbles into the
liquid to form a floating scum blanket. The air flotation tanks use air diffusers or impellers
to add air bubbles  to the liquid which creates a floating scum blanket.
                        *.-**'"        '            *         -        ®
The dissolved air  flotation  unit adds air in the wastewater while the wastewater is under
pressure. The liquid is allowed to become supersaturated with air and  then it is released to
another tank at atmospheric- pressure. The decrease  in pressure allows minute bubbles to
form throughout the liquid volume, thereby  helping to create a scum blanket.

The vacuum flotation unit uses the same principle as the dissolved air unit. However, in this
unit,  the air is added  to the  wastewater in a tank at atmospheric pressure and allowed to
become supersaturated with air. The wastewater is then transported to another tank where a
vacuum is applied, thus  reducing the pressure and  one'e again allowing minute air bubbles to
form, again resulting in the formation of a scum blanket.

Inspection and Pretesting
The flotation tank should be inspected  and cleared of any debris that may have collected
during construction. The tank should be checked for proper installation of the air lines,
valves, and pumps if  the  flotation unit is a pressure or  vacuum flotation  tank. The air
flotation  tank should be inspected  for proper installation of the impeller and motor or air
lines, diffusers, and blower.
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Regardless of the type of flotation tank, the sludge removal mechanism should be inspected
for proper clearances and alignments and the flotation and sludge removal units should be
lubricated according to the manufacturer's instructions and the lubricant types recorded and
properly filed.

Before running the  flotation for its three to four hour break-in period, the sludge removal
unit should be  electrically jogged through one complete cycle and the depth of the rakes in
the water, the clearance and level of the rakes at the sludge trough, and the alignment of the
rakes and  drive mechanism checked. The pressure or vacuum pump should be inspected for
tight mountings, smooth operation,  overheating,  undue  noise or vibration, and proper
clearances and alignments. Pressure and amperage readings should be taken and recorded.

Start-Up
During  start-up the unit should be inspected periodically to ensure  that the skimming
mechanism is operating properly and that the scum blanket does  not become too large or
too thick to handle.

SETTLING TANKS
Settling tanks are commonly used not only in primary treatment of wastewater, but also as
a unit operation in the secondary treatment processes of activated sludge and trickling
filters. The purpose of the primary sedimentation tank is to  remove the larger suspended
solids and the  floating material from the  wastewater prior to  discharge to the receiving
waters or to the secondary treatment units. The  primary sedimentation  tank effectively
removes from 50-65 percent of the suspended solids and from 25-40 percent of the BODp-
from domestic wastewater. The secondary type settling tanks treat the biological unit's
effluent. The operation is the same as the primary except the surface loading and sludge
volume  are usually less than  the primary. The intermediate settling tank is used between
trickling filters  for improved efficiency and operates in the same manner as  the primary and
secondary settling tanks.

Inspection and Pretesting
The inspection and pretesting of the primary clarifier is particularly important because it is a
major unit with many  mechanical parts submerged during  operation. The basin and piping
should be cleared of all debris. All control gates and valves should be checked for smooth
operation  and  proper seating  and the sludge collector  mechanism checked for proper
alignments, clearances, and  lubrication. The drive mechanism should be inspected for tight
mountings, drive alignment, clearances, safety devices, and proper lubrication; the weirs
                                        26

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should be inspected for level. The manufacturer's literature should be reviewed to see that
the mechanism has been installed, lubricated and is operating according to their instructions.

The mechanism  should be run for three to four hours prior to letting wastewater in. The
raking mechanism should be cheeked for proper clearance and smoothness of operation and
the drive motor  inspected for any undue noise, vibration, and overheating, and.an amperage
reading taken and recorded. During start-up the scum removal equipment should be checked
to see that it is removing the scum properly.

Start-Up
During start-up of the primary clarifier, the raw sludge should be removed from the clarifier
(settling tank) when it consists of four to eight percent dry solids as indicated by the total
or  suspended  solids test.  Sludge removed  two times a  day will  normally be of this
consistency. The sample of raw sludge is usually taken from a sludge pit before pumping.
The sludge is  mixed in the pit and a representative sample taken directly from the well.
Samples are also collected from openings in pipes near the sludge pumps or from the pump
itself.  When pumping  to  digesters, the sludge should be as thick as possible and sludge
withdrawal (pumping) rates should be low in order that water is not drawn into the sludge.
As the sludge  is  being removed, it should also be checked for the amount of grit present. If
appreciable amounts are present, then more, frequent removal of grit is necessary and the
                                                   --x
grit removal equipment should be inspected.

Operating personnel should be trained  in the clarifier operation  and be provided with a
schedule for .sludge pumping during start-up and normal operation. When the sludge appears
thin (appreciable  amount of water)  by visual  inspection, pumping should  be stopped.
Although the  total solids test is the only accurate means for determining the density of the
sludge, it is too slow for control of routine pumping operations. Many operators use the
centrifuge test for quick results and most experienced operators can visually determine if
the sludge is the proper density to pump by sounding for the depth of sludge. Sounding for
depth enables the operator to determine the sludge quantity to be removed and thus the
time required  for pumping to remove that quantity of sludge. The laboratory test should be
run to.,verify the operator's judgment  and tor the plant operating records. Other laboratory
tests should be run for plant operation and control such as the DO, BOD, Suspended Solids
and Settleable Solids. The plant's O & M Manual should contain a list and frequency of the
necessary laboratory tests for the clarifier. The procedures for running these tests are found
in  Standard  Methods, and  the WPCF's  Publication No. 18,  "Simplified  Laboratory
Rrocedures for  Wastewater Examination"; these  references should be included in the
supervisor's list of necessary books and manuals for plant operation.
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Three  of the more common operating problems  that may affect the operation of the
sedimentation basins are too thick a sludge, septic sludge, and short circuiting.
       1.     If the  sludge  removal equipment operates erratically, it  may be
              because of  a  thick sludge. After  inspecting to  see that some
              mechanical failure has not  occurred, and a thick sludge has been
              identified, steps to remove the sludge should be taken. More frequent
              and  controlled removal of the sludge should cure and prevent this
              condition. It may be necessary to dewater the tanks and remove the
              sludge by hand if there is a possibility of damaging the equipment.

       2.     If the sludge is not removed often enough, it may become septic,
              indicated by a "rotten egg" odor and possibly a rising sludge  blanket.
              In this  case, it  may be beneficial to chlorinate the clarifier contents
              to reduce odors  and delay  the decomposition of the sewage while
              corrective action is being taken. Chlorinating  the clarifier contents
              should  be done  with caution because it will affect any following
              biological processes. More frequent removal of the sludge will cure or
              prevent this condition if it is not the result of a  mechanical failure.

       3.     Short  circuiting  is another  problem that might occur at start-up.
              Short circuiting occurs when a high velocity area exists in the basin
              and  can be indicated by a rising sludge, flow of sludge particles in the
              effluent, and septic sewage. Usually, proper baffling, weir type and
              elevation,  and  inlet design  can prevent  or  reduce this problem by
              altering the flow regime within the clarifier.

CHLORINATION
Chlorine is a gas, heavier than air, extremely toxic, and corrosive in moist atmospheres. The
gas is irritating to the  mucous membranes of the nose, to the throat, to the  lungs and heavy
exposure can be fatal. All persons handling chlorine should  be aware of these hazardous
properties. The  operator's on-site training,  the Water Pollution Control Federation's MOP
No. 1,  "Safety  in  Wastewater  Works," the Chlorine Institute's "Chlorine Manual," 4th
Edition, the EPA's "Procedural Manual for Evaluating the  Performance  of  Wastewater
Treatment Plants,"  Contract No. 68-01-0107, and the chlorine equipment supplier can help
familiarize the operators with the hazards of chlorine and with the use of various pieces of
                                         28

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protective  equipment  such as  oxygen systems.  The operator's  training should include
instructions in the dangers of chlorine, the use of emergency equipment and repair kits, first
aid, and the methods and procedures for handling chlorine containers.

Although clorine is primarily used as  a disinfectant in wastewater  plants, it has a variety of
other uses also.  In a  preehlorination unit,  chlorine is  added for disinfection and odor
control, but it can also be applied to  reduce plant BOD load, to aid in settling, to control
foaming, and to  help remove oil. Throughout other points  in the plant, chlorine may be
added  to  wastewater  for control and prevention  of odors, sludge bulking, filter flies,
corrosion, digester foaming, filter ponding, and as an aid in sludge thickening. Following all
other treatment units and processes, chlorine is added primarily for  disinfection.

Disinfection is strictly  defined as the destruction of all pathogenic organisms. By destroying
the pathogenic and nonpathogenic organisms, chlorine helps prevent nuisances such as odors
from developing  and protects municipal  water  supplies,  bathing beaches, and  other
recreational areas from waterborne diseases.

Inspection  and Pretesting
As mentioned under On-Site Operator's Training arid the Safety  section, an experienced
individual in the  use and handling of  chlorine should always be on hand prior to start-up to
guide  the  new  operating personnel in  the inspection  and pretesting  of the chlorine
equipment. In general, the chlorination equipment should be inspected for installation and
calibration, and  the  pressure  readings should  be recorded.  The  connections should be
cheeked  with  ammonia  water with the  chlorinator  only partially open. Having  the
chlorinator only partially open will aid the operator if he has to shut down the chlorinator
quickly. All valve positions should be checked and the valves should be inspected for proper
seating. Safety equipment and emergency repair kits should be on hand and inspected.  The
"Handbook of Chlorination" by George Clifford White, Chapter 3, discusses start-up of the
chlorination equipment in detail.

Start-Up'
Once the  equipment  has been inspected  and pretested,  start-up" should  produce  few
mechanical problems. The operator should measure the chlorine feed and chlorine residual
and  adjust the system to provide the required amount of chlorine residual determined by
the supervisor, state, and/or federal regulatory agencies.

SUMMARY
The preceding sections  have  provided  recommendations and procedures for starting up
pretreatment,  primary treatment,  and chlorination facilities;  however, the procedures are

                                         29

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not  absolute.  It  cannot  be stressed  enough  that  the procedures should  be used  in
conjunction with  the  manufacturer's recommendations and instruction and advice from
experts in the field of wastewater treatment plant operation.

Before starting up any of the pretreatment, primary treatment, and chlorination units, they
should be thoroughly inspected, pretested, and made ready for start-up. During start-up, it is
important  that  the equipment be  inspected  periodically  to  ensure that the units  are
performing properly and  to  note any problems or indications of potential problems that
might arise. The electric motors should  be properly lubricated and the lubricant type filed;
and readings  such as pressure and amperage should be recorded both when the motor is
under load and without load. The plant personnel should try to anticipate any contingencies
that might occur during start-up and to plan for the proper corrective action to handle these
problems.
                                        30

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                       "  "         SECTION IV
                     START-UP OF SECONDARY FACILITIES
The secondary treatment processes used in municipal wastewater treatment aid in providing
the high degree of treatment required to  ensure the protection of the receiving waters.
Secondary treatment processes consist' of complex biological systems that require a delicate
balance of  food and  environment. Since it is  during  start-up  that  the  microorganism
population required for proper treatment is being developed, the start-up of secondary
processes is more critical than  their normal  operation because of the increased need for
process control. A proper start-up of the secondary process ensures maximum treatment
efficiency from the initial day of operation.

This section provides considerations and techniques for starting up secondary treatment
processes. The guidance is  general enough to apply to any size  or  type of secondary
treatment process. It is  assumed that the previous sections' considerations on preparing for
start-up and start-up of the pretreatment, primary  treatment, and chlorination facilities have
been incorporated into the start-up procedures.

Common operating problems and their solutions not discussed in this manual can be found
in the  EPA's "Procedural Manual for Evaluating the Performance of Wastewater Treatment
Plants," and the WPCF's MOP No. 11, "Operation of Wastewater Treatment Plants." Each
treatment plant's O & M Manual should also contain valuable information to help solve
operating problems.

ACTIVATED SLUDGE
The  activated sludge  process is a biological  wastewater  treatment  process. The activated
sludge, in general, consists primarily of bacteria, protozoa, and rotifers living in the sewage
in the  presence of dissolved oxygen.  The activated sludge converts organic substances in
finely  divided,  colloidal, and dissolved form  into oxidized  products and a settleable floe.
This floe, now as activated sludge, is removed  from the wastewater by sedimentation leaving
a high quality effluent. The biological action is accomplished in aeration tanks where the
organisms are maintained in an aerobic environment by introducing oxygen into a mixture
of activated sludge arid sewage. The settling of the floe is accomplished in secondary settling
tanks.

Raw sewage does not contain sufficient organisms to properly stabilize the organics present
in the  wastewater; therefore, it is necessary to develop sufficient microbial  mass (activated
                                        31

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sludge) and distribute and maintain the mass throughout the wastewater to accomplish the
designed treatment. As the organisms feed on the organics and increase in number, they are
removed  from  the  aeration basin,  and  settled in  a clarifier;  appropriate  portion  is
recirculated to  the aeration basin to provide  the desired  mass of organisms needed to
efficiently treat  the wastewater.

The primary objective  of start-up is to develop  a proper microbial floe (activated sludge) as
quickly as  possible. This development will result in an  increase in the reduction of
bipchemical oxygen demand (BODg) and a reduced load on the receiving waters as the
activated  sludge floe is settled and removed in the sedimentation tanks. A portion of this
settled  floe (activated  sludge)  is   returned  to  the  aeration tanks  until  a desirable
concentration of organisms,  expressed as  mixed liquor suspended solids (MLSS), has been
established  in  the process.  Once this concentration is  established,  excess settled  floe
(activated sludge) is wasted to maintain the proper concentration of MLSS in the process.

The activated sludge process has various modifications which provide different approaches
to biological waste treatment  depending on the  characteristics of the wastewater to be
treated. Table 1 illustrates some of the differences in these process modifications. (Note the
differences in MLSS concentration.)

It is essential that laboratory analysis and control schedules be provided and followed during
start-up. Although the  following procedures should apply to starting up any of the process
modifications of the activated sludge process, the supervisor should take advantage of all the
information available to him. The person(s) responsible  for  start-up should  obtain the
process design  criteria such  as influent flow, BODg loading,  sludge age,  detention time,
temperature and mixed liquor suspended solids (MLSS) concentration. The use of these
parameters as control  parameters  should be discussed with the design engineer for his
comment  and for any corrections he feels should be made. Once the correct information has
been obtained, the desired Start-Up MLSS concentration can be estimated. Using the design
flow and design  MLSS  concentration and by measuring the actual flow and calculating the
BODg loading entering the  basin, the  desired Start-Up MLSS concentration in a single
aeration basin can be determined.

     Design MLSS concentration  for      Actual  Flow  tothe Basin
     aeration  basin  to be  started       Design Flow  to the Basin
        Ac t ua1 BOD  Concen t ra t1 on  _  Actual  "minimum" Start-Up MLSS
        Design BOD  Concentration      Concentration  for a  Single  Basin
                                       32

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Process
Mod i f i ca t i on
Conventional

Complete - mix

Step-aeration

Mod I f ied-aerat Ion


Contact-stabi ) izat ion

CO
CO
Extended-aeration

Kraus process
High-rate aeration


Pure-oxygen systems


* Contact unit
Sludge
Age
(Pays)
5-15

5-15

5-15

.2-. 5


5-15


20-30

5-15
5-10


8-20



BOD Removal
Efficiency
% '
85-95

85-95
!
85-95

60-75


80-90


75-95

85-95
75-90


85-95



** Solids stabilization unit


(Simi lar



MODIFICATIONS
to Wastewater Engineering


MISS, mg/llter
1,500 - 3,000

3,000 - 6,000

2,000 - 3,500 ,

200 - 500


*(1,000 - 3,000)
**(4,ooo -10,000)

3,000 - 6,000

2,000 - 3,000
4,000 -10,000


6,000 - 8,000



NOTE: The MLSS
TABLE 1
OF THE ACTIVATED SLUDGE
, McGraw-Hill Company, 1


Appl I cat ion
Low-strength domestic wastes, susceptible
to shock loads
General application, reststant to shock
loads
General application to wide range of
'waste
Intermediate degree of treatment where
cell tissue in the effluent Is not
objectionable
Expansion of existing systems, package
plants, flexible

Small communities, package plants,
flexible
Low-nitrogen, high-strength wastes
Use with turbine aerators to transfer
oxygen and control the floe size, general
appl ication
General application, use where limited
volume is available, use near economical
source of oxygen

values are not for use as the design MLSS

PROCESS
nc., 1972, Figure No.' 12-3)

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The above equation is for a single aeration basin. If there  is more than one basin in the
plant,  the design MLSS  will have to be  varied accordingly to obtain the "minimum"
Start-Up MLSS concentration for any one aeration basin. This proportioning to the basins is
necessary in order to maintain the proper food-to-microorganism ratio (F/M) and sludge age.
By starting only one or two basins, the other basins can be started using the activated sludge
from the others as seed sludge and start-up of these basins should be accomplished more
quickly and efficiently. (See Examples 1 and 2.)

The "minimum" Start-Up MLSS concentration is the concentration that should be built up
before wasting any activated  sludge during  start-up. (If the flow into the plant is stepped in
increments during start-up, then the Start-Up MLSS concentration  will  also have to be
incremented  accordingly.)  It should not be necessary to change  the  value for the MLSS
concentration obtained due to any temperature fluctuations or minor changes  in flow, but
by maintaining the  "minimum" MLSS concentration value within plus or minus 10%, a
manageable start-up  with good efficiency should be possible. The optimum value for MLSS
concentration will have to be determined  by  adjusting the  return sludge rate and  wasting
rate, which changes the MLSS concentration  in  the basin,  and by comparing the BODg
removal  efficiency  through  the secondary  process.  The  optimum  value for  MLSS
concentration will be when the BODc in the final clarifier effluent is minimized.

Ferric  chloride or polymers can help develop the MLSS concentration  by concentrating the
solids used for recirculation while minimizing final effluent BODe loading on the receiving
waters. The  quantity of  chemical  or  polymer to be added  to the  settling tank can be
determined  in the laboratory by  jar tests.  Caution should be  exercised when adding
chemicals in  order that toxic cation levels are not allowed to develop. Adding chemicals as
coagulant aids may give  erroneous  values for MLSS concentration because some of the
suspended solids may be chemical floes and not biological floes. It will be necessary to test
for mixed liquor volatile suspended solids (MLVSS) concentration which would indicate the
amount of biological suspended solids present and remove the chemical floe error.

Inspection and Pretesting
Before  putting the  preceding paragraph's  information into effect, a responsible person
should inspect and pretest the activated sludge facilities to ensure that:

       1.     All debris is removed from the basins and piping systems.

       2.     All gates  and valves are  opened and closed  and  checked  for
              smoothness of operation and seating in the closed position.
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       3.     The effluent weirs are checked for level.

       4.     All nozzle heads of  the  froth  control system  are open and  on
              securely.

       5.     The inspection of the air system includes:
              A.     Checking the air filter and condensation trap.
              B.     Checking the air lines for leaks.
              C.     Checking valves for proper and smooth operation.
              D.     Inspecting the  blower for proper lubrication, clearances, and
                     safety guards.
              E.     Inspecting the coupling from the motor for proper alignment.
              F.     Inspecting the mounting of  the motor  and  blower  for
                     tightness.
              G.     Inspecting air gauges for proper operation and calibration.

       6.     The air  headers  are raised and  lowered and  checked for smooth
              operation.

       7.     The diffusers are inspected to ensure that the air can go through
              freely.

NOTE: Figure No. 2, Sample Pre-Start-Up Inspection Record, page 12 will be a useful form
for inspecting and testing the f aeiEties.

If mechanical aerators  are  used, they should be rotated first by hand  to- ensure proper
alignment and  smoothness  of operation. The mounting of the unit should be carefully
inspected to  ensure it is fastened securely. The motor should be lubricated properly and the
lubricant type recorded and  properly filed. All electrical motors should  be jogged to see that
the wiring is connected correctly and that the motors are turning in the  correct direction.

After inspecting the facilities for installation,  operation, and calibration in accordance with
the manufacturer's instructions, the facilities are ready  for testing. The facilities should be
"wetted down," preferably with domestic  water and

       1.     The piping system should be inspected for  leaks of  either air or
              water.
                                           35

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       2.     The gates and valves should again be checked for seating.

       3.     The froth control system should be checked to see that the nozzles
              are spraying the correct pattern and in the proper area.

       4.     The air system and its safety devices should be inspected for proper
              operation.  (The  air  pressure and  amperage  readings  should  be
              recorded and filed.)

       5.     The motors should be inspected for vibration, noise, and overheating,
              and an amperage reading taken and recorded.

After inspecting the air system for proper operation, run the system for three to four hours,
inspecting periodically for any problems.

The inspection and pretesting of the final settling tank is discussed in Chapter III (Start-Up
of the Pretreatment, Primary Treatment, and Chlorination Facilities).

Start-Up Procedure
Prior  to  start-up, a composite sample of the raw sewage  to be treated should be obtained
and a settleable  solids  test run. From this test, very carefully remove the filtrate  and
determine the BODg and the  Chemical Oxygen Demand (COD).  The  filtrate  is used to
approximate the primary clarifier effluent characteristics. The BODc and COD tests should
be  performed on several samples in order  to obtain a BODg  to COD relationship. This
relationship allows the COD test to be used for process control in lieu of the much longer
BODg test during start-up. This test  will enable a quick measure of  the efficiency through
the activated sludge treatment process and a quick means  of estimating the ratio of organics
(BODg)  to  the  microbial  population  (MLSS) usually  referred  to  as  the  food-to-
microorganisms ratio (F/M). A normally operating plant typically has an F/M ratio of 0.2 to
0.5, except for extended aeration which operates at a lower F/M of 0.1 and less.

The BODg to COD relationship should be  used  with discretion because there may be a
change  in  the  ratio  of  the two  parameters,   possibly caused by  an increase in  the
nonbiodegradable  organics or due to solids carryover, which could prohibit or invalidate
such a relationship. To reduce the error between  the COD/BODg ratio, it may be useful to
obtain another COD/BODe ratio by testing the liquid portion of a Suspended Solids test for
BODg and COD (referred to as the Dissolved BODg and Dissolved COD). The Dissolved
COD/BODg relationship will  probably be more consistent than the other COD/BODg ratio,

                                           36

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but it will take longer to obtain. Keep in mind that the Dissolved COD/BODc ratio may not
be the same for all areas of the plant; therefore, depending on the circumstances of start-up,"
the COD/BODc ratio may have to be determined at a number of locations in the plant for
start-up control. (Both the COD and BODg tests should continue to be run during start-up
to confirm the COD/BODg relationship.) Once the process becomes operational, the COD
test should be run as a useful process control tool although the BODc is the standard quality
control parameter required by most regulatory agencies.

On the  second and third  day after the effluent  from the primary clarifiers begins entering
the aeration basin, the BODg,  COD, MLSS and sludge volume index (SVI) should be
determined on samples from the aeration basin and  the final clarifier. (The relationship
between COD and BODg of the influent may not be the same as that  of the effluent;
therefore, BODp should be run daily.) The SVI is indicative of the settling characteristic of
the floe in the final clarifier and will indicate the possibility of sludge bulking. Generally, an
SVT in  the range  of 50-150 indicates a good settling sludge.  Visual observation of the
settleable solids test is also beneficial in obtaining information on,the settling characteristics
of the activated sludge in the final clarifier.

The following are examples of the preceding procedures:

       EXAMPLE 1:    MLSS DETERMINATION:    SINGLE BASIN
              Conventional Treatment
                    Single Aeration Basin
                                                             "*         -f
              Design Conditions
                    Flow   =,  1MGD      ,	._..-."   . .   '    -
                    BODg Loading  =  37 Ib. BODg/day/1000 ft3 of basin
                    Temperature  =  70° F.
                    MLSS  =   1500 mg/1       _';
                   ' BODg Concentration   =   150 mg/1
                                              _ -              j
            "  -Actual Conditions
                    Flow   =   .75 MGD
                    BODg Loading  =  28 Ib. BODg/day/1000 ft3 of basin
                    Temperature  =  65° F.
                   * BODr Concentration   =" 150 mg/1
                         o                 -              ,  »                 j.  '

*Obtained J!rom  analysis on raw sewage,  from analysis  of clarifier effluent  or  from
BODr/COD relationship.
                                         37

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              "Minimum" MLSS  concentration  =
       EXAMPLE 2:  MLSS DETERMINATION: MULTIPLE BASINS
             Conventional Treatment
                    Ten (10) Aeration Basins with 54,000 ft3/basin
                          (Three to be started)

             Design Conditions
                    Flow  =   16 MGD
                    BOD5 Loading   =  37 lb/day/1 000 ft3 of basin
                    Temperature  =  70°F.
                    MLSS  =  1500 mg/1
                    Total Volume of Basins =  54,000 ft3 x 10  =   540,000ft3
                    BODg Concentration   =  150 mg/1

             Actual Conditions
                    Flow  =   4 MGD
                    BOD5 Loading   =  31 lb/day/1000 ft3 of basin
                    Temperature  =  65° F.
                    BODg Concentration   =  150 mg/1

       "Minimum" MLSS   =

             Flow to basin(s) to be started/number or volume of basins
             Design flow to basin(s)/total number or volume of basins

                      BOD   Concentration  to Basins
                    x   „   . - fTT^r — = - -. - x  Design MLSS  =
                        Design BODj.  Concentration          3
                                         !!Jn ^/l x  1500 mg/1 -  1250  mg/1
                                                           3     -      3
                               p           n
                               Basins    150
The number of basins required to be started under field conditions is determined by the
flow. The design flow for Example 2 is 16 MGD to ten basins, or 1.6 MGD/basin if all basins
are equal in volume. Therefore, 4 MGD would require 2.5 basins (4 MGD divided by 1.6
MGD/basin). Since it doesn't equal an even number of basins, use the next higher number
                                      38

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(in  this  example, 3 basins). Therefore, starting up three  (3)  basins will have a better
f ood-tomieroorganisms (F/M) ratio than if all ten (10) basins were used, or only one basin,
and thus will have a more effective start-up.               -            -

Hie start-up of the activated sludge process can be accomplished by using seed sludge or raw
waste water  to develop a suitable  microorganism "population expressed as  mixed liquor
suspended solids (MLSS).

       1.     The  use of a seed activated sludge  will provide the most reliable
              means of start-up. When available,  enough  seed sludge should be
              placed into the aeration basin to provide at least 500 mg/1 of MLSS
              in order to handle the plant flow. Maximum aeration should be used
              during start-up to provide a minimum Dissolved Oxygen content of 2
              mg/1 and to aid mixing. With the seed sludge aerated, flow into the
              aeration basin should be introduced at approximately 10 percent of
              plant flow if possible and increased in daily increments of 10 percent
              if there is no indication of the process deteriorating. This will enable
              the treatment process  to produce a quality effluent as the MLSS
              concentration is increasing.

       2.     If raw"sewage is used, begin start-up of the activated  sludge process
              by filling the aeration basin-with the raw  sewage,  bypassing the
              primary clarifier. This  will provide the greatest number of available
              seed organisms without seed sludge. The aerators should be operating
             - before raw sewage is let  into the basin  to keep the  diffusers from
              clogging and to provide mixing, and should be  operated at a rate to
              maintain a minimum Dissolved Oxygen (DO) residual of 2 mg/1. The
              aeration basins, if possible, sho.uld then be bypassed for a period of
              approximately  eight hours during which  the  raw sewage  is being
              aerated. After  approximately seven  hours, the  aerators should, be
              turned off and the mixture in the basin allowed to settle for thirty to
              sixty minutes, after  which additional raw sewage should be, allowed
              to enter and displace the basin supernatant. The mixture should then
            ,  be reaerated  and allowed  to settle as  before. This practice should be
              continued  until the MLSS is at least 500 mg/1 at which  time the
              aeration. basins should be placed on  continuous flow  and the MLSS
              • allowed  to build up to the "minimum" MLSS as calculated. As the
              MLSS continues to increase,  the aeration rate may be reduced if the
                                           39

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              DO is peater than 2 mg/1. The DO test should be run frequently
              during this period, usually every two hours during start-up, to ensure
              that the oxygen requirements of the organisms are met.

Regardless of which of the above methods is used, no return sludge should be wasted during
start-up; the sludge return pumps should be returning at a rate such that no sludge blanket
will develop in the settling tanks. This procedure will ensure the maximum number of
available organisms, as activated sludge will be returned to the aeration basin.

When the proper  MLSS concentration is reached for full flow, the return activated sludge
pumping rate  should be adjusted.  The estimated return  sludge pumping  rate can be
determined from the settleable solids analysis:

       % MLSS in the 6Q-mmute settleable solids test expressed as the decimal equivalent
         x  (Influent flow rate plus the return sludge flow rate)   =   Return Activated
                           Sludge Pumping Rate

EXAMPLE 3: ADJUSTED RETURN SLUDGE PUMPING RATE DETERMINATION
              Flow to Aeration Basin   =  4 MGD
              Return Sludge Flow   =  2 MGD
              Volume  of  MLSS in  60-minute  settling  test  =   400  ml  in
                                  2 liters =  20% =  ,20

              Therefore
              Adjusted Return Sludge Rate  =  ,20 x  (4+2) MGD   =  U.MGD

              Adjusted  Return Sludge  Rate   =  1.2 MGD  x 695
                                  = J35  gallons/minute

Therefore, the return activated sludge pumping will have to be reduced from 2 MGD to 1.2
MGD or 835 gallons/minute. This rate  may have to be adjusted to maintain the proper
MLSS in the aeration basin.

When the return sludge  pumping rate has been established, sludge should begin to form a
blanket in the settling tank. After the sludge blanket accumulates to  approximately 1 foot
above the tank bottom, the excess waste activated sludge pumping rate can be determined.
The waste activated sludge pumping rate  will also change the return sludge pumping rate.
                                         40

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EXAMPLE 4:  WASTE ACTIVATED SLUDGE PUMPING RATE DETERMINATION
       This can be determined in one of two ways:

       I.     Activated Sludge Plant with all basins operating.
             Assume these values were obtained from laboratory analysis:
                    'MLSS   -  2800 mg/1 (Used in Step (1))
                    Return Sludge, Suspended Solids  = 5600 mg/1
                           (Used in Step (6))
                    Influent, Suspended Solids  =  60 mg/1
                           (Used in Step (2))
                    Average Daily Flow =  4 MGD (Used in Step (2))
                    Volume of Aeration Basin  =   0.55 MG
                           (Used in Step (1))
                    Design Sludge Age  =  Mean Cell Residence Time
                           = • 5 days (Used in Step (4))
                   ' Return Sludge Pumping Rate  = 835 GPM

              Determine:
          —    ---     Step (1):  Ibs of Solids in Aeration-Basin  =
                      r"    MLSS (mg/1)  x Volume of Aeration Basin

     '    -                         (MG)  x 8.34
                                  = 2800 mg/1 x 0.55 MG x 8,34

                             * 12.700 Ibs.  of Solids In the Aeration Basin

                     Step  (2);  g|^ Solids Added by Primary Clarffier Effluent

                      Influent Suspended Solids  (mg/1} x Avg. Daily Flow (MGD)
                                           x 8.34 jb2/MG
                                                   mg/1

                                                                     lbs/MG
                                          =  60 mg/1 x 4.0 MSD  x  8.34
                                                                     mg/1
                         = 2,000 Ibs/day Added  by Primary Clarifier  Effluent
                     Step (3):  Sludge Age (days) =
                      	HISS in Aeration Basin (Ibs)^	
                      Solids Added by PrimaryClarifier Effluent (Ibs/day)
                                                        _  12.700  Ibs
                                                        ~ 2,000 Ibs/day
                                                             » 6.4 days
                                         41

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                  Step (4): If the Sludge Age was less than the design value of
                                five days, no wasting should be done. Under
                                normal conditions, the sludge age will indicate
                                when to  reduce or increase the wasting rate.
                                The design sludge age
                                                — /

                                       =  5 days; therefore, rearranging
                                          the equation in (3),

                             Ibs.  MLSS
                             to be maintained  = Sludge Age x Solids added by
                                                Primary Effluent
                                              =       5 days x 2,000 Ibs/day
                                                                 10. OOP  Ibs.
                  Step (5) :   Therefore, the proper  amount of MLSS to be  wasted
                                 - 12,700 Ibs. - 10,000 Ibs. = 2,700_ Ibs.
                  Step (6):   Waste activated sludge pumping rate =
                             Amount of sol ids  to be wasted (Ibs) in a 24-hour period
                                Return sludge  concentration (mg/1)  x 8,3^ - n —
                                                                           mg/ I
                                                - 2.700 "»/d.        = 0.058  MGD
                                                5,600 mg/1  x 8.3
                                                     0.058 MGD  x  695 |gg- - ^O.S  6PH
This waste activated sludge pumping rate will, therefore, change the return sludge pumping
rate from 835 GPM to 794.5 GPM (835 - 40.5 GPM).

The reason the waste activated sludge pumping rate is set for 24 hours is to eliminate any
rapid changes to the sensitive biological cultures.

       2.     Another means of estimating the wasting rate is to use the desired MLSS
              concentration obtained earlier in the start-up proceedings.

       Assume these results were obtained from the laboratory tests:
                                           42

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                     =  2800 mg/1
              Return Sludge, Suspended Solids  =  5600 mg/1
              Primary Effluent, Suspended Solids  =  60 mg/1
              Average Daily Flow =  4 MGD
           ,„  Yolume of Aeration Basin = 0.55 MG
                     and also
           -  Desired MLSS  = ,2720 mg/1 plus or minus 10%

     Step (1):   Amount of  Solids  to  he wasted ~- =,
             " ,  (Laboratory MLSS  - desired MLSS} x Average Daily Flow x B.3k
                       (2800  -  2720  mg/\) x 4 MSO x 8.31* - 2670 Ibs/day
     Step (2);   Waste  activated sludge pumping rate =
                          2670 'bs/day        m  ^^ mQ
                      5600 mg/J x 8.3^ ""f,^    •              =   39.6 GPM
Therefore, the return sludge pumping rate will be 795.4 GPM (835 - 39.6 GPM).

The waste activated sludge pumping rate and the return sludge pumping rate may have to be
adjusted if -the characteristics of the wastewater  change thus changing the desired MLSS
concentration. The waste activated sludge pumping rate will have to be increased or
decreased in order to maintain an optimum value for MLSS in the aeration basin in order to
proyide the best possible treatment of the wastewater.

When the plant has stabilized, a good activated sludge should settle rapidly leaving a clear,
odorless and stable supernatant. The floe should appear granular with sharply defined edges,
be golden brown in color, and have a musty odor. However, there are some conditions that
may occur during start-up that will indicate a poorly operating process. The operator should
not expect immediate results from any of the control  procedures that are presented. An
experienced operator will be  of greatest value  when these problems arise in the wastewater
treatment process.

During start-up an unstable effluent will  probably  result due to the inadequate biological
treatment. Chlorination is often used to reduce health hazards on the receiving water. State
and Federal regulatory agencies should be contacted to ensure that no harm  will  come to
the wildlife or fish present in the receiving waters as a result of heavily chlorinating the plant
effluent. The use of alum, ferric chloride and polymers as an aid to settling in final settling
tanks will help reduce the BODg loading on the receiving waters. The coagulants should be
thoroughly mixed with the aeration basin contents before being released to the final settling
tank,

                                          43

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During start-up, when the MLSS are low, the aeration basins may experience severe foaming.
Foaming is believed  to  occur because of synthetic detergents  and other surfactants in
conjunction with high aeration and low aeration MLSS, The foam contains sludge solids,
pease, and bacteria  and should be brought under control as quickly as possible. Water
nozzles  using screened sewage or domestic water have been used successfully to control
foaming. Defoaming agents are also used or possibly used in conjunction with water nozzles
to help control the foaming.  The operator may be able to reduce the aeration rate while
maintaining his DO and building up his MLSS to aid in the control of foaming. The foaming
should decrease as  the MLSS continues to  increase in  the aeration basin and the process
approaches stability.

Sludge bulking may occur during start-up due to overloading the basin. Sludge bulking is
indicated by a poorly settling sludge and poor sludge compaction. The sludge blanket in the
final clarifier becomes deeper and rises to overflow the weirs. The sludge settleability
decreases as indicated by a significant rise in the SVI and the sludge appears light and fluffy.
Sludge bulking is associated  with the growth of filamentous organisms that attach them-
selves from one floe to  another  and prevent compaction of the sludge particles  and  poor
settling  results.  Another  cause of  sludge bulking is bound water in which the bacteria,
composing the floe, swell because of the addition of water and thereby decrease in density.

When sludge bulking occurs,  it is usually associated with  low pH, low  DO, low nitrogen
concentration, high F/M, industrial waste, or septic sewage. The primary purpose of control
is to increase the sludge age or decrease the F/M ratio.

Low DO - The DO  should be  checked initially to see that at least 2 mg/1  of DO exist in the
aeration  basin; if not, then  inspect the aerating equipment to see  that it is functioning
correctly and  increase the aeration rate. If the aerators or blowers are operating at capacity,
then additional  aerators, diffusers,  or blowers  may have to be added. The design  of the
aeration rate should be investigated if aerators have to be added.

Low pH -  Lame is  usually added, often with flocculent aids, to raise the pH and control
bulking by improving the settling  characteristics  of the sludge while corrective  action is
being taken.

High F/M (Low Sludge Age)  - To  reduce the  F/M, the organic load (F) on the basin is
decreased by  reducing the influent flow to the  basin or the MLSS (M) is increased by
increasing the return sludge   rate and  decreasing  the wasting rate. Both of  these actions
should increase the sludge age.

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The plant records should be reviewed in order to determine what caused the problem and in
order that future operations can  take measures to prevent the same conditions from
occurring again.

Rising sludge should not be confused with sludge bulking.  In a rising sludge, the settling
characteristics and compaction are good.  Rising sludge occurs as a result of too long a
detention time in the clarif ier. The sludge rises in chunks from the size of a pea to as large as
a basketball, usually forming a brown, fine scum or froth on the surface of the settling tank.
The  sludge undergoes  denitrification  with the  release of nitrogen  gas that  becomes
entrapped in the sludge causing it to rise to the surface. By  increasing the rate of return of
activated sludge pumping or increasing the sludge wasting rate and decreasing the sludge age,
the problem of rising sludge should be corrected. *

If the start-up of the activated sludge process is in winter, it will take longer to build up the
mixed liquor suspended solids which may produce strain on other operations of the plant.
In winter, the loading and air rates  change. The-sewage  will  require less air and more solids
to bring about efficient treatment. Usually the ambient temperature is not significant unless
it raises or lowers the temperature of the liquor more than 10° F.

The operator should use caution when, changing the mode of operation of this process or
any other. An extreme  change or allowing the process to go too far the other way can be
just as detrimental to treatment efficiency as the existing problem. Therefore, make any
changes gradually and in an orderly step-by-step  fashion.

ACTIVATED SLUDGE CHECKLIST*
To supplement the preceding recommendations for starting up an activated sludge process,
the following checklist has been provided:

  I,    literature Review

       A.     Manufacturer's Literature

       B.     Facility's Operation and Maintenance Manual
 *It is assumed that  the previous  sections'  recommendations concerning Preparation for
 Start-Up and Start-Up of the Pretreatment, Primary Treatment and Chlorination Facilities
 have been followed and an outline of start-up procedures has been made.
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C.     "Operation of Wastewater  Treatment Plants," Environmental  Protection
       Agency, Technical Training Grant No. 5TT1-WP-16-03

D.     WPCF Manual of Practice No.  11, "Operation of Wastewater  Treatment
       Hants," 1966

Preparation for Start-Up

A.     Meet with consulting engineers and start-up experts.

       1.      Obtain design parameter values.

              a.     Flow into aeration basin

              b.     BODc loading and concentration
                         
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             4.      Volume of basin(s) to be started

      C.     Calculate "minimum" MLSS concentration for start-up.

IE.   Start-Up Procedure

      A.     With seed sludge

             1.      Turn aerators on and maintain a minimum DO residual of 2 mg/1.

             2.      Fill the aeration basin(s) with raw sewage or water.
                                                                  ^

             3.      Add  seed sludge to bring MLSS of basin(s) being started to at least
                  -   500 mg/1.

             4.      Let flow into aeration basin(s) at approximately 10% of the design
                     and increment at 10% a day.

             5.      Return all activated sludge from the final settling tank.

      B.     Without seed sludge

             1.      Turn aerators on and maintain a minimum DO residual of 2 mg/1.

             2.      Fill basin(s) with raw sewage.

             3.      Let flow into aeration basin.

             4.      Bypass flow for eight hours and aerate mixture in the basin for seven
                     hours.                                            ,

             5.      Turn off aerators and  allow the  mixture to settle for  thirty to sixty
                     minutes.

             6.      Again let flow into the aeration basin, bypass flow for eight hours,
                     reaerate mixture and allow it to settle; continue until  the MLSS is at
                     least  500 mg/1.
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             7.     Let basin accept continuous flow.

             8.     Return all activated sludge from the final settling tank.

IV.   Process Monitoring During Start-Up

      A.     Measure operational control and effluent standard parameters to include:

             1.     MLSS in the aeration basins

             2.     DO in the aeration basins

             3.     Influent and effluent BODg and COD

             4.     SS in the secondary clarifier

             5.     SVI in the secondary clarifier

             6.     Calculate F/M

      B.     Calculate return  activated sludge pumping rate when aeration basin MLSS
             concentration reaches "minimum" MLSS concentration.

      C.     Permit sludge blanket to form  in final settling tank to approximately one
             foot of depth.

      D.     Calculate activated sludge wasting rate and begin wasting activated sludge.

 V.   Normal Operation

      A.     Continue monitoring  process  by  measuring the operational control  and
             effluent standard parameters to include:

             1.     Influent and effluent BODg concentration

             2.     MLSS in the aeration basin
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              3.      SS in the secondary clarifier

            .  4.      SVI in the secondary clarifier
                            t
              5.      DO in the aeration basin

              6.    "  Calculate F/M _

       B.     Adjust process

              1.      Return sludge rate

              2.      Wasting Rate

              3.      Air Supply
References for Additional Information:
1.     "Operation of Wastewater Treatment Plants," Environmental Protection Agency,
       Technical Training Grant Np. 5TT1-WP-16-03, Chapter 7.

2.     WPCF  Manual of Practice No. 11, "Operation of Wastewater Treatment Plants,"
       1966, pages 108-122.

3.     Wastewater Engineering, Metcalf and Eddy, McGraw-Hill Book Company, Inc., New
       York, 1972, pages 482-533.

4.     McKinney, Ross E., Microbiology for Sanitary Engineers, McGraw-Hill Book Com-
       pany, Inc., New York, 1962 pages 213-237.

5.     Standard Methods for  the Examination of Water and  Wastewater, 13th Edition,
       APHA, AWWA, WPCF, 1971.

TRICKLING FILTERS
The  biological process involved in the trickling filter is  essentially the same as with  the
activated sludge.  In general, the trickling filter removes  the dissolved and finely divided
organic solids from sewage and biologically oxidizes the solids to a more stable material. The
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filter media, consisting of rock, redwood slats or synthetic material, provides surface area
for the development of slime growths or  zoogloeal mass, containing bacteria,  protozoa,
algae, fungi, worms, and insect larvae. As the effluent from the primary clarifiers passes
through  the filter, the gelatinous growth retains much  of the suspended,  colloidal, and
dissolved material contained in the sewage. The material is  utilized as food by the organisms,
thereby reducing the organic concentration of the sewage. The excess film that accumulates
from the growth of new organisms is periodically or continually sloughed from the filter and
separated in the final settling tanks. In this manner, a large portion of the BODg loading is
removed from the wastewater.

During start-up, the objective is to build up this slime growth so that the desired removal
efficiency can commence as soon as possible.

Trickling filters may be classified as either  standard rate  (low rate) or high  rate. The
standard rate filter accepts  loadings  of 25-100 gpd/sq  ft of  surface area  and 5-25 Ibs
BODg/day/1000  cu ft  of media. This  type  filter  usually is six  to eight feet  deep and
rectangular  or circular in shape. It is dosed intermittently by automatic or periodic pumping
from the dosing tanks. The dosing rates are sufficient to  keep the filter media from drying
out.

The material sloughed or washed -from the filter media is stable, easily settled, humus-like
material, often containing worms, snails,  and insect larvae. The  effluent from the final
settling tank usually has a BO DC on the order of 20-25 mg/1.

The high rate filter usually has loadings of 100-1000 gpd/sq ft of  surface area and 25-300 Ibs
BODg/day/1000 cu ft of media. The high rate filter is normally three  to eight feet deep and
rectangular  or circular  in shape.  This type  filter has  a continuous  loading  due to
recirculation of  the  filter  effluent. Because of  the high loadings,  sloughings  are  more
frequent; therefore, the sloughed material is less stable, lighter and more difficult to  settle
than  the standard rate filter. The  BODg in the  effluent of  the  final  settling  tank is
commonly in the range of 20-50 mg/1.

If a high rate filter has a loading greater than 300 Ibs BODg/day/1000 cu ft of media, it is
termed a roughing filter or intermediate filter due to the lower efficiency of BODg removal
(50 to 70 percent). This is usually used when high organics loadings are expected and little
treatment is needed at this stage.
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Inspection and Pretesting
A responsible person should ensure that:
                   t-
       1.     All debris is removed from the underdrain system and basins.

       2.     All valves and gates have been opened and closed and inspected for
              proper seating.

       3.     The orifice openings are as specified.

       4.     The proper lubricant has been used  and recorded for future refer-
              ence.
                                !
       5.     AH exposed metal is protected.

After assuring that this has been done, the arm of the filter (if it is a rotating type of filter)
should be rotated by hand and inspected for vibration or roughness. If possible, the filter
should then be loaded hydraulically and the rotation inspected and the orifice openings and
flow checked.

If the filter is a fixed nozzle  type,  after the inspection, hydraulically  load the filter and
check the nozzles for clogging from debris left from construction and inspect the spray
pattern to see that the media is being wetted properly.

The inspection  and  pretesting of the final settling tank is similar to the inspection and
pretesting of the settling tank  in Chapter III (Start-Up of the Pretreatment, Primary Treat-
merit and Chlorination Facilities).

Start-Up Procedure
After pretesting the filter, start the wastewater flow to the distributor arms, observing the
rotation  of the arms to see that  they are operating smoothly and that the waste is distrib-
uted evenly oVer the filter media. The revolutions per minute should be logged. If the filter
is a fixed nozzle system, after inspection, start the wastewater flow to the nozzles. Inspect
the spray pattern to see that the waste is distributed evenly over the filter media. Debris will
clog some of the nozzles, and it is important that the nozzles be cleaned as soon as possible.

In a high rate filter, the recirculation of the final clarifier effluent helps to prevent odors and
ponding of the filter by flushing  the media, reducing  the  detention  time, and keeping a
                                           51

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constant load on the filter. If a standard filter is being started up, it is important that the
filter media be  kept as wet as possible. Although a siphon is  present to dose the standard
filter, during start-up the flow into the plant may be such that the time interval involved
with  an automatic  siphon will  be so long that the filter will dry out.  Some means of
recirculation such as the  use of a portable pump should be provided to make sure that the
filter will remain wet and to add recirculated final clarifier effluent to the  filter. Recircula-
tion of the high rate and standard rate filter (if possible) should reduce the time required for
growth to develop on the filter media.

It will take several days for growth to develop on the media, depending on the time of year,
weather conditions,  and  the character and strength of the wastewater.  During this time, a
poor effluent may result. Chlorinaion and coagulants are often used to reduce the pollu-
tional load and  the health hazard on the receiving waters. Caution should be exercised when
using heavy chlorination in order that no harm will come to any wildlife or fish present in
the receiving waters by a large chlorine loading.

The usual control tests performed on the influent and effluent are BODg  or  COD, sus-
pended solids, and total solids. These  tests  will indicate the removal efficiency through the
filter and settling tank; pH and DO tests should also be run to help indicate  the condition of
the filter.

The start-up and operation of the  trickling filter is one of the most trouble-free types of
secondary treatment. During start-up, most of the problems that may plague trickling filters
such as ponding, odors, and psychoda flies will not occur. If cold weather is present, it will
inhibit biological growth  to some degree and, therefore, it may take longer for slime growth
to develop on the filter. Cold weather is usually not a problem, but occasionally the filter
will freeze, especially the standard rate which has intermittent operation. Operate the  high
rate filters, if possible, in parallel with little or no recirculation. Standard rate  filters should
be operated on  a continuous loading if at all possible. This procedure will decrease the  time
the wastewater in the filter is exposed to the cold temperature.  The orifices  or sprays should
be  adjusted to  reduce the spray  effect. The erection of  wind screens  has also been  used
successfully to  help  reduce the problem of freezing. The filter  should not be stopped unless
there is danger to the mechanical facilities. The dosing tank should also be covered to reduce
the effects  of  freezing. If the supports on  a rotary nozzle  were  adjusted during warm
weather, they will have to be readjusted due  to the temperature effects on the expansion
and contraction of the support wires or rods.
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References for Additional Information
1.     "Operation of Wastewater Treatment Plants," Environmental-Protection Agency,
       Technical Training Grant No, 5TT1-WP-16-03, Chapter 6.

2.     WPCF  Manual of Practice No. 11, "Operation of Wastewater Treatment Plants,"
       1966, pages 98-107.

3.     Steel, Ernest  W.,  Water Supply and Sewerage,  McGraw-Hill Book Company, Inc.,
       New York, 1960, pages 522-546.

4.     MeKiriney, Ross E., Microbiology for Sanitary Engineers, McGraw-Hill Book Com-
       pany, Inc., New York, 1962, pages 199-212.

STABILIZATION PONDS AND AERATED LAGOONS
A stabilization pond, or oxidation pond, in general, is a shallow body of water contained in
an earth basin, designed for the purpose of treating wastewater. Stabilization ponds are used
as complete treatment process, or as secondary treatment for settled sewage, or as polishing
for  secondary  effluents. The ponds are most commonly used for secondary treatment and
are  classified .into three groups: aerobic, anaerobic, and facultative (aerobic and anaerobic).

       1.      An aerobic pond primarily contains algae and bacteria in suspension,
            '  and aerobic conditions prevail  throughout its depth. One type of
              aerobic pond  depends upon the algae to provide sufficient oxygen to
              satisfy the BODg  loading applied to the pond. This type of aerobic
              pond is usually 6 to 18 inches in depth to provide conditions suitable
              for algae growth. This type of aerobic pond is normally used only in
              small communities because of the land area required.

              A  second.type of aerobic pond employs mechanical aeration or air
             - diffusers to supply most  of the oxygen required^ This pond has a
              depth of three  to six feet. Both  types  of aerobic ponds  have
              additional oxygen transferred to the liquid  through surface aeration.

              Stabilization of the organic matter in aerobic ponds occurs in two
              steps.  -First, the carbonaceous matter in sewage is broken down by
              the aerobic organisms with the formation  of carbon dioxide. This
              carbon dioxide is used by the algae  during photosynthesis with the
              liberation of oxygen. As a result, some of the organic carbon in the

                                          53

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       sewage is converted into algal cells which supply the sewage with
       additional oxygen to support further aerobic decomposition. It is
       important that the algae and microbial floes be separated from the
       pond  effluent to minimize the pollutional loading on the receiving
       waters.  The  removal of these floes is usually accomplished in
       secondary settling tanks.

       Aerated  lagoons are similar to the aerobic pond, except  the algae
       growth is replaced by mechanical aerators or diffusers and the lagoon
       is usually 6 to 12 feet deep. Although the mixing caused by aeration
       keeps most of the lagoon contents in suspension, usually some solids
       settle  and undergo anaerobic decomposition. Therefore,  the aerated
       lagoon may be further classified not only as aerobic but also facul-
       tative (aerobic and anaerobic) which is similar to the facultative
       stabilization pond with the mechanical aerators or air diffusers
       replacing the algae growth as the primary source  of oxygen for the
       bacteria.

2.     The anaerobic stabilization  pond is loaded to such an  extent that
       anaerobic conditions exist throughout most of the liquid volume.
       Depths up to 20 feet have been used with this type of pond. Stabili-
       zation is brought about  by the anaerobic decomposition of the
       organic solids  to organic acids, cell tissues,  carbon dioxide, methane
       and other gaseous end products similar to an anaerobic digester with-
       out external heat.

3.     The facultative pond is a combination of the two stabilization ponds
       mentioned previously. It is the most common stabilization  pond and
       ranges in depth from two to six feet. The pond consists of an aerobic
       top layer and anaerobic bottom layer.  Stabilization  comes  about
       through the aerobic decomposition of  the top layer and  anaerobic
       decomposition of the bottom layer. The top layer, referred to as the
       aerobic layer,  requires an oxygen source such as surface mechanical
       aerators or an  algal growth. The maintenance of the aerobic top layer
       minimizes the  odor problem associated with the anaerobic pond.
                                   54

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Inspection and Pretesting
The earth levees of the pond should be inspected for seepage; erosion,'soil sterilization and
weedicide. The grass cover and type of grass used should be inspected by the supervisor to
see it meets all regulatory agency requirements. If mechanical aerators  are being used, the
supervisor should see  that they are installed, lubricated, and inspected  according to the
manufacturer's instructions. Air diffuser systems should be inspected to see if all areas of
the lagoon are receiving equivalent amounts of oxygen. This  can be done visually and with
DO tests. The air blower and motors should be inspected for installation, lubrication, noise
and vibration, clearances, and alignments.                             "

Start-Up
Since the facultative pond is the most common type of stabilization pond, the start-up
procedure will deal with this type of pond, with algae as the primary source of oxygen.

If possible, start  up the pond  in  the  warmer part of the year. Generally, the warmer the
contents of the pond, the more efficient the treatment. At least' one to two feet of water
should  be in  the pond  before waste  is introduced in order to reduce the possibility of
offensive odors and aquatic weed growth during the initial operation.

Algal blooms will usually appear in seven to twelve days after waste is introduced. A definite
green color of the pond's contents is evidence of a flourishing algae population. Anaerobic
decomposition of the  bottom  sludge causes bubbles to come to the surface near the inlet
point of the pond.

Waste should  be introduced intermittently to the pond during the initial start-up so that the
pond does not become overloaded. The pH should be monitored and be kept above 7.5, if
possible. A high  pH is essential to encourage  a balanced anaerobic decomposition  of the
bottom  sludge. It  also indicates  high algae activity,  since the algae removes the carbon
dioxide from the liquid during metabolism which tends to keep the pH high.

Dissolved Oxygen (DO) tests are also run on the pond contents. The values of DO and pH
should be recorded to  help evaluate the condition of the pond. The operator should seek to
correlate his visual observations with control tests to better maintain and operate the pond.

The pond levees should have been seeded before start-up and inspected for any damage due
to boring animals. Typical problems with  ponds such as scum or odors should not occur
during start-up. Weeds may occur during the start-up period and should be  removed as
quickly  as possible. Weeds can hinder  circulation and  provide areas for mosquito breeding
                                           55

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and, if not removed, will quickly multiply. little trouble can be expected from insects if
weeds or other plant growths are removed. Other minute animals that may hinder the pond
operation can best be handled with approved insecticides or other chemicals. Caution should
always be exercised when using chemicals around the pond because they may be harmful to
the operation  of the pond. Another problem that may occur during start-up is freezing.
Mixing the contents and windbreaks have been used to reduce the problem of freezing.

References for Additional Information
1.     "Operation  of  Wastewater Treatment Plants," Environmental Protection Agency,
       Technical Training Grant No. 5TT1-WP-16-03, Chapter 9.

2.     Manual of Wastewater Operations, Texas Water Utilities Association, Lancaster
       Press, Inc., Lancaster, Pennsylvania, 1971, pages 283-301.

3.     Wastewater Engineering, Metcalf and Eddy, Inc., McGraw-Hill Book Company, Inc.,
       New York, 1972, pages 551-569.
                                         56

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                                    SECTION V
                START-UP OF THE SLUDGE HANDLING FACILITIES

One of the major objectives of  wastewater treatment is solids removal. The handling of this
sludge can be the most time-consuming and expensive operation in the wastewater' treat-
ment plant. Proper start-up of the sludge handling facilities will ensure that efficient treat-
ment and disposal of the sludge is accomplished.

This section provides considerations for starting up the more common chemical condition-
ing and sludge dewatering units, and considerations and techniques for starting up  an
anaerobic digester. The guidance is general enough to apply to any type or size of unit and
any  size of anaerobic digester. The guidance involved with the units is not intended  to
duplicate or replace the individual equipment manufacturer's instructions and recommenda-
tions. The equipment manufacturer's recommendations and instructions should always  be
consulted whenever installing, inspecting, pretesting, lubricating, and maintaining his equip-
ment. It is assumed that the previous sections' considerations on preparing for start-up;
start-up of the pretreatment, primary treatment, and chlorination facilities; and start-up of
the secondary facilities have been incorporated into the start-up procedures.

Common operating problems and their solutions not discussed in this manual can be found
in the EPA's "Procedural Manual for Evaluating the Performance of Wastewater Treatment
Plants," Contract No. 68-01-0107, and the WPCF's MOP No. 11, "Operation of Wastewater
Treatment Plants." Each plant's O & M Manual should also contain valuable information to
help solve operating problems.
                                                               /
ANAEROBIC DIGESTION
In the anaerobic sludge digester, bacteria decompose the organic solids in the absence of
dissolved oxygen. The organisms break down the complex molecular structure of the solids,
setting free the  "bound" water (water that  will  not separate from the  sludge solids) and
obtain molecular oxygen and food for their growth. Anaerobic digestion reduces the waste-
water solids to a mixture that is relatively odor-free, readily dewaterable, and capable of
being disposed of without causing a nuisance.

In the digestion process, organic solids are liquefied, the solids volume is reduced, and
methane gas is produced by the sequential  action of two  different groups of bacteria living
together in the same environment. One group consists of saprophytic organisms, commonly
                                          57

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referred to as the "acid formers." In the liquefaction step, the saprophytic bacteria attached
to the sludge particles secrete extracellular enzymes which in turn liquefy and hydrolize the
complex molecules of the solids into simpler compounds and give off end products, primari-
ly organic acids. The second group of organisms, which utilize the organic acids produced by
the saprophytic bateria, are  the  "methane formers." The organic  acids (mainly acetic,
propionic,  and butyric) produced  in the first step are acted on  by the "methane formers"
which secrete  intracellular enzymes that  break down  the  organic acids and  form the
methane and  carbon dioxide gas characteristic  of  the anaerobic digestion  process. The
methane formers are not as abundant in raw wastewater as the acid formers and require an
optimum pH range of 6.5 to 7.5 .

Anaerobic  digesters are classified according to their loading rates  and not their reaction rates
since  the rate of biological activity is fixed. They are usually operated at a temperature of
90° - 95°  F.  provided by heating coils inside the digester tank walls or by external heat
exchangers. The low rate, conventional  or standard  rate digester has a loading of 0.04 to
0.07 Ibs. of volatile solids/day/cubic foot of digester volume and has an average  detention
time of 39 days. The low rate digester uses a single tank and has an active zone  where
anaerobic decomposition  takes  place and  a quiescent zone above which solids separation
takes  place.

The  most  common conventional-digester is the two-stage digester and  consists of two
separate  tanks. In the first tank, digestion occurs and the sludge is withdrawn to a second
tank,  usually unheated, where the sludge undergoes solids separation and sludge compac-
tion. The second tank also provides seed sludge in the event the first tank develops operating
problems. The  high rate digestion  process is similar to the two-stage digester of the conven-
tional process except the loadings  are greater, usually 0.15 to 0.4 Ibs. of volatile solids/day/
cubic foot of digester volume with an average  detention  time of fifteen (15)  days. Mixing
and digestion occur  in the first tank and the sludge is then removed to a second tank where
solids separation and sludge concentration take place under quiescent conditions.

The  object of start-up  of any  anaerobic digestion process is to provide a suitable
environment for  the  bacteria to  prosper by controlling  food supply,   volatile acid
concentration,  total alkalinity concentration, mixing, temperature and pH. During start-up
of an anaerobic digester,  using  no seed sludge or chemicals and with no upsets, digestion
should proceed similar to the plot of Figure No. 3. (Summary plot of data observed during
batch digestion studies)

Figure No. 3 shows that the volatile acid production, methane production, and  alkalinity are
not stable for a number of days after start-up begins. The use of seed sludge during start-up

                                           58

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places initial start-up on the right side of the graph where the above parameters are more
stable. Therefore, the best means of starting a digester is with the aid of a well-digested
stable seed sludge.
                      	ACCUMULATION.OF VOLATILE ACIDS
                           IF GAS PRODUCTION IS PROHIBITED
                       A   	
                    VOLATILE
                     SOLIDS
                           (LIQUEFACTION
                           AND ACIDIFICATION)
                         1.00
•  B   -
VOLATILE
'  ACIDS
       ( METHANE
        FERMENTATION)
                                   TIME (days)
                                   FIGURE NO. 3
         SEQUENTIAL MECHANISM OF ANAEROBIC SLUDGE DIGESTION

(Courtesy of Texas Water Utilities Association "Manual of Wastewater Operations" Fig. 18-2)

Inspection and Pretesting
The inspection and pretesting of the sludge digester is complex and involves pumping the
sludge,  mixing the sludge, withdrawing  the sludge, and withdrawing the gas and liquid.
Because anaerobic digestion involves biological active cultures and explosive gases, start-up is
no  time to  have^the gas withdrawal system, heat exchanger, sludge pump, or mixer break
down due to an oversight in inspecting and testing the equipment.
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Again, it is stressed that the plant supervisor should observe construction of the digester and
installation of all piping, valves, and equipment to ensure that it is installed according to the
manufacturer's recommendations and instructions.

In general, the supervisor should see that:

       1,      All debris from the piping and tank is removed.

       2.      All valves  are  inspected for proper and smooth operation, and the
               seating checked.

       3.      The safety devices such as flame traps and pressure release valves are
               checked for proper operation.

       4.      The sludge pumps are free of debris,  properly lubricated, no undue
               vibration or noise, and the drive alignments are correct.

       5.      The heat  exchanger (if  the plant is so equipped)  is inspected to
               ensure all  water, sludge, and heating connections are correct and no
               leaks are present.

       6.      All gages are inspected and calibrated.

       7.      The  mixers are  operating satisfactorily, properly  lubricated and
               mounted securely.

There should also be some means available to mix a lime slurry and add it to the digester
contents. The equipment should be inspected to see that they will operate properly and the
required chemicals are on hand prior to start-up.

Start-Up Procedure
The start-up  of the anaerobic digestion process can be accomplished by using seed sludge or
raw wastewater to begin the biological decomposition of the sludge:

       1.      The first step  in starting up any anaerobic digestion process using
               seed sludge is  to  estimate the proper quantity  of seed sludge based
               upon the initial digester loading. If the volume of seed sludge avail-
               able is limited, it may be necessary to estimate the digester loading

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              based  upon the available seed sludge. Example 5 contains sample
              calculations for estimating the volume of seed sludge based upon the
              initial  loading. If the calculated volume of seed sludge is too large or
              otherwise prohibited, the procedures in Example 5 can be reversed to
              obtain an estimated digester loading rate for a known volume of seed
              sludge. This procedure  permits the seed sludge to digest only a
              portion  of  the  total  sludge feed and uses  only a portion of the
              digester volume  until the digester can be filled with digesting sludge.
              However, when  starting a digester without using full sludge  flow,
              provisions for disposing of the remainder of the feed sludge will have
              to be made.
EXAMPLE  5:   SEED SLUDGE ESTIMATION (Primary sludge as feed)
       Assume  these  sewage characteristics exist  in  the  primary clarifier(s)  at
       start-up:
             Influent, Suspended Solids  =  250 mg/1
             Effluent, Suspended Solids  =  150 mg/1
             Influent Flow  = 10 MOD ** Effluent Flow

       (1)    Calculate Ibs. of sludge accumulated in clarifier(s)

              Ibs.  in  Influent = 10  MGD  x 250 mq/1 x 8.34 ] bs/l"IG
                                                                 mg/1
                                                        = 20,800  Ibs.

              Ibs.  in  Effluent = 10  MGD  x 150 mg/1 x 8.3^
                                                                 mg/1
                                                        =  12/500  Ibs.
              Ibs.  accumulated  in  one "day - 20,000 -  12,500  Ibs.
          =   8,300 Ibs. of  sludge to be  ptfrnped  to the  digester.
              Assume that the seed sludge and primary clarifier have been analyzed
              and these results obtained:

              Primary  Clarifier Sludge = 5% total solids (TS) with 70% volatile
                                         solids (VS)

              Seed Sludge =  10% total solids (TS) with 60% volatile solids (VS)
                              at  9 Ibs/gal
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       Estimate the amount of sludge to be pumped to the digester per day (1%
       solids = 10,000 nag/l)

                 =  ^ bg • Q..f. SJ udge  to be removed to  d I gest er
                      consistency of sludge  x 8.3^ - /•? —
                                                        mg/ 1
                 =   8.300  Ibs/day             8,300  Ibs/day
x 8.34     TT-   50,000 mg/1 x
                                   TT-      ,              .    -
                                mg/ 1                           mg/ I
                                                        = 0.0199  MGD
                                                        = 19,900  GPD
       The pumping time can be determined based upon the pump capabilities of
       the plant.

       For instance, if  the plant has a combined pumping capability for sludge
       removal of 100 GPM, then the time of pumping equals:

              19,900 gallons of sludge to  be removed  per day
                           100 gallons per minute
              = 19$ minutes of pumping time per day

       This time should be divided through as long a period of time as practical in
       order to provide as continuous a feeding of sludge as possible to the digester,
       in this case possibly one hour and six minutes for each shift.

(3)     Determine Ibs/day of volatile solids pumped to the digester:

       Ibs/day of volatile solids  =  (Volume or rate of sludge, GPD) x (%  sludge
                                         solids expressed as decimal equivalent)
                                         x (% volatile  solids  expressed as
                                         decimal equivalent) x (8.34 Ibs/gal)
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                                        =  (19,900 GPD)  x (.05)  x
                                        (.7) x (8.34 Ibs/gal)

                                        =  5,808 Ibs/day

(4)     The design engineer should be called upon to aid in selecting a suit-
       able volatile solids loading ratio.

       Normal loading rates undergoing active digestion are 0.03 -  0.10 Ibs.,
      -VS/day/ibs of VS undergoing digestion. These values are based upon
       the design loading rate of the digester, and the design engineer should
       be of help in selecting volatile solids loading rate.             ^

   .   For this example assume:  	0.05 Ibs.  VS/day	
                                1 ib.  VS undergoing digestion
(5)    Estimate the amount of seed sludge needed to treat the loading at
       5,808 Ibs/day from the clarifier.
       	0.05  Ibs.  VS/day           =        5,8p8  Ibs/day	
       1  Ib.  VS undergoing digestion      Weight  of seed  sludge  VS
       By rearranging  terras

         f*|lp Ibs.  of  VS of seed sludge - 116,200 Ibs.  of VS

       Therefore
         	116,200  Ibs. VS           	
         (%  TS of Seed)  x  (% VS of Seed) x Density of  Seed Sludge"
                                     '            116,200  Ibs.  VS
                                         ---(.1)  x (.60)  x  9 Ibs/gal
                                     =  215.185  gals', of  Seed Sludge
       Fill the digester with the calculated  or  available volume  of seed
      •sludge'and the remaining volume with raw sewage until the liquid
       flows over the maximum overflow pipe or until the floating cover
       lifts  12 inches off the corbels.  Heat the contents 90-95° F. and

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maintain within plus or minus 1° F. Since the methane bacteria are
upset  relatively  easily  by  rapid  temperature  variations,  the
temperature should be maintained above 90° F. and any change in
digestion temperature should be  brought about gradually. After the
temperature is stabilized, begin adding the raw sludge at a rate no
greater than the predetermined rate to the digester and circulate and
mix the contents. If a gas mixing device is used, the gas mixer will be
inoperative until gas production occurs and the circulation system on
the  heat  exchanger will have  to be  used for mixing. Mixing is
important because  it provides intimate contact between  the seed
organisms and  the raw sludge  and   distributes the  heat  evenly
throughout the sludge mass. Feeding from the clarifier or thickener
should be well-controlled to provide a sludge of at least four percent
solids content and  to  provide  as continuous a feeding as possible.
This usually  results in  almost immediate start-up of the digestion
process. The  initial feeding rate may have to be reduced because of
the amount of seed sludge present in order not to overload the seed
sludge. (See Example 5.)

On  the  second day  of start-up, begin  determining  the  control
parameter values. The volatile  acids test  takes two   -  three hours,
the alkalinity test (15 minutes),  pH test (five minutes), gas analysis
(30  minutes), and the volatile  solids test  (one hour), assuming the
operator, lab  technician, or chemist has experience in running the
tests. The volatile acids, alkalinity, pH and gas analysis should be
determined  three  times  a day and volatile solids daily, assuming
digestion is proceeding without any problems, in which case the tests
should be run more often. The values of the control parameters may
not  change peatly in an eight-hour period, but the values obtained
from each shift will give a  means of confirming any previous control
action taken.

Initially, the  alkalinity and pH may decrease but should stabilize in
four  or  five  days as the  methane  formers begin  to reproduce.
However,  the methane formers  have  a lower rate of reproduction
than the "acid formers," and if the feed rate is too high, the process
may fail because the excess volatile solids produced will inhibit the
methane producing organisms. If the volatile acids begin to increase
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              beyond twice the buffering alkalinity capacity of the digester, gas
              production is decreasing, and the pH is decreasing, seed sludge should,
              be added from another digester or the second stage digester and the
              sludge feeding rate  should  be decreased. If  these controls are not
              available, add  chemicals for buffering alkalinity as required. It  is
              important to maintain a suitable environment in the digester for the
              methane formers,  that  is,  a  pH  of  7.0  to  7.5,  alkalinity
              approximately twice that of the volatile acids, and a temperature of
              90-95° F. The amount of buffering  alkalinity to be  added can be
              determined by taking a sample from  the digester and adding the
              buffering alkalinity until the sludge has a neutral pH (7.0) and then
              adding a  proportionate amount, in a slurry, to the digester contents.
              It is essential  when adding chemical aids to provide adequate mixing
              in  the digester.  The  operator, chemist, or  lab technician should
              exercise  caution  when adding buffering alkalinity  to a digester to
              neutralize excess  volatile  acids and  raise the  pH. The  buffering
              alkalinity added may cause the concentration of any cations present
              to reach toxic or inhibitory levels. (See Table 2.)
                  Cation                      Concentrations  (mg/1)
                Calci un\ (L i
                Sod i urn
                Potassium
                Magnes ium
Moderately
Inhi bi tory
3500 - 5500
2500 - 4500
2500 - 4500
1000 - 1500
Strongly
1 nh i bi tory
8000
12000
8000
3000
                                 TABLE 2                        ;
INHIBITORY CONCENTRATIONS OF ALKALI AND^ ALKALINE-EARTH CATIONS
        (McCarty, P. L., and McKinney, R. E., Journal WPCF, April, 1961)


              With the use of seed sludge for start-up, the gas analysis and volatile
              solids test is a good measure of the digestion process. The CO0 and
                                                                       &
                 ^  (carbon dioxide and methane) ratio and the volume of volatile
                                         65

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              solids  destroyed should  not  change  markedly after  start-up or
              digester  upset  may  be indicated.  An  increase  in  volatile  acid
              production (followed by or with a decrease in alkalinity) will precede
              the reduction of gas production in the digester, indicating digester
              upset.

       2.     If  seed sludge is not available, fill the digester with raw sewage and
              heat the  contents to 90-95°  F. and add raw sludge mixed with the
              buffering alkalinity slurry to the digester.

              If seed sludge is not  being used for start-up, then the use of chemicals
              to control alkalinity and pH is recommended. On the second day of
              start-up,  begin  performing the volatile  acids, alkalinity,  pH, gas
              analysis and volatile solids test as mentioned previously. By taking
              the values  of the volatile acids and alkalinity  test, the amount of
              buffering alkalinity to be added can be  calculated using a volatile
              acids-to-alkalinity ratio of 0.5. During normal digester operation, the
              VA/Alk  should  equal  .3 to  .4,  but for start-up .5 is used as a
              conservative figure in order to avoid adding toxic levels of cations to
              the digester. The amount of buffering alkalinity to be added should
              be adjusted after -each  of  the tests or during  each shift since the
              volatile acids and alkalinity will change quickly.

EXAMPLE  6:   CHEMICAL ADDITION FOR DIGESTER CONTROL DETERMINATION
       Assume these conditions exist in the digester on the 3rd  day of start-up:
              Volatile Acids (VA)   =  1000 mg/1
              Alkalinity (Alk)   =  500 mg/1

              The quantity of alkalinity to  ensure a favorable environment for the
              methane  bacteria =
                      Volatile  MCid Concentration  in  the sludge _  1000 mg/1
                                   w'A/A Ik ratio = 0.5                     675
                                                                       =  2000 mg/1

 The alkalinity quantity to be added by chemical addition:
                     Alkalinity quantity for the methane bacteria - Alkalinity in
                     the sludge = 2000 mg/1 - 500 mg/1 = 3J1QQ mg/1
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If  the volume of sludge in the digester is  known, the weight of
chemicals to be added can be determined:

Assume the volume of sludge  in  the digester  = .224  MG:
         (Ibs.)  chemical  to be  added In  a slurry
=  Volume  of sludge in  digester  (MG)  x  alkalinity  to be
                                                         1 b/MG
                                 added  (mg/1) x  8.34
                       =  .224 MG  x 1500 mg/1 x  8.34
                                                        mg/1
                                                         Ib/MG
                                                        mg/1
                  = 2,800  Ifas. of bicarbonate  alkalinity

The  chemical dosage calculated above is a great deal to add to the
sludge and will  be expensive. However, note that in the example, on
the third day of start-up, the volatile acids equal 1000 mg/1 and the
alkalinity is only 500 mg/1. If the digestion process  is monitored
closely on the  second day of start-up, this  amount  of chemicals
should not be necessary. Instead, only a small quantity should have
to be added because, initially, the alkalinity should be greater than or
equal to the  volatile acids (see Figure No. 3) as can  be seen from
Example No. 6. (Note:  The time of three days used in Example No.
6  is arbitrary and does not necessarily reflect the true time span
under actual start-up conditions.)

When  the  volatile  acids  concentration  begins  to  decrease
(approximately seven days) and  the  methane production begins to
increase  greatly, chemical additions  should be decreased.  At this
time, the methane formers are  beginning to  feed and reproduce,
thereby reducing the volatile  acids and  producing methane gas and
their own buffering alkalinity. If, after 10 to 14 days,  the digestion
process shows little sign of stabilizing, decrease the feed rate and stop
chemical addition. Inspect the feed  sludge and digester sludge  for
cation or industrial toxicity and monitor the control parameters to
see if digestion recovers. If possible,  place second stage sludge back
into the primary digester to provide methane producing organisms
and  buffering capacity,  if toxicity is not present. If,  on the  other
hand, when raw sludge is added, the volatile acids do not rise or
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              decrease sharply, the alkalinity continues to rise, the pH does not
              drop further and the volatile solids reduction continues to increase,
              then progress is indicated. Gas production should be monitored and
              should show an increase in the methane content of the gas. Normal
              operation usually is established within 30-40 days, without the use of
              seed sludge, as indicated by a methane gas concentration of 60-70%
              of the digester gas composition. If foaming  occurs, reduce the feed
              sludge loading or add well-digested sludge from another digester. If
              mechanical mixers are used, reverse their direction to mix the foam
              into the sludge mass.

ANAEROBIC DIGESTION CHECKLIST*
To  supplement the preceding recommendations for  starting up any Anaerobic Digestion
Process, the following checklist has been provided:

  I.   Literature review to become  familiar with the Anaerobic Digestion Process

       A.     Manufacturer's literature on the digestion process equipment

       B.     Facility's Operation and Maintenance Manual

       C.     "Operation  of  Wastewater  Treatment  Plants,"  Environmental Protection
              Agency, Technical Training Grant No. 5TT1-WP-16-03, Chapter 8

       D.     WPCF Manual of Practice No.  11, "Operation of  Wastewater Treatment
              Plants," 1966, pages 39-62

       E.     WPCF Manual of Practice No. 16, "Anaerobic Sludge Digestion," 1968

  II.   Preparation for Start-Up

       A.     Meet with consulting engineers and start-up experts.

              1.      Obtain design parameter values.

                     a.     Volume of  digester(s)

*It is  assumed that the previous sections' recommendations  concerning Preparation for
Start-Up and Start-Up of the Pretreatment, Primary Treatment  and Chlorination Facilities
have been followed and an outline of start-up procedures has been made.

                                          68

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                    b.      Volatile solids loading to digester(s)

                    c.      Solids concentration of sludge pumped to digester(s)

      B.     Estimate actual start-up conditions.

             1.     Estimate volatile solids and total'solids loading to digester(s).

III.   Start-Up Procedure

      A.     Seed Sludge

             1.     Estimate  the  percent total solids and volatile solids and the  density
                    of the seed sludge.

             2.     Calculate the  amount of seed sludge to be added based on estimated
                    start-up loading.

             3. "    Add seed sludge to the digester(s) and fill the remaining volume with
                    raw sewage.

             4.     Heat contents of the primary digester(s) to 90-95° F. and maintain
                    within plus or minus 1  F.

             5.     Mix   contents , of  the  primary  digester(s)  thoroughly  and
                    continuously.

             6.     Pump raw sludge to the digester(s) at the estimated solids  loading
                    rate as continuously as possible.

             7.     Measure the control parameters.

                    a.      Volatile acids approximately three times a day

                    b.      Total  alkalinity approximately three times a day

                    c.      pH approximately three times a day
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              d.     Gas analysis for methane and carbon dioxide approximately
                     three times a day

              e.     Volatile solids approximately once a day

              f.     Calculate VA/Alk

       8.     Adjust process.

              a.     Increase feed if volatile solids are lower than desired.

              b.     Decrease feed if volatile solids are greater than desired.

B.     Without  seed sludge

       1.     Fill the digester(s) with raw sewage.

       2.     Heat the contents of the digester to 90-95° F. and maintain within
              plus or minus 1° F.

       3.     Mix the contents thoroughly.

       4.     Pump raw sludge to the digester at 10% of design loading.

       5.     Measure the control parameters.

              a.     Volatile acids (VA) three times a day

              b.     Total alkalinity (Alk) three times a day

              c.     pH three times a day

              d.     Gas analysis for methane and carbon dioxide once a day

              e.     Volatile solids (VS) once a day

              f.     Calculate VA/Alk
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              6.  ,    Adjust process.

                     a.      Calculate chemical quantity to be added to digester contents.

                     b.      Add chemical in a slurry to the digester to maintain the pH
                            and VA/Alk ratio favorable to the methane organisms.

                     c.      Reduce chemical feed as digestion process stabilizes.

                     d.      Increase loading by 10%.

 IV.    Normal Operation

       A,     Monitor control parameters of pH, VA/Alk, gas analysis and volatile solids,

       B,     Adjust feed until the sludge in the digester is in equilibrium.

References for Further Information
1.     "Operation of Waste-water, Treatment Plants," Environmental Protection Agency,
       Technical Training Grant No. 5TT1-WP-16-03, Chapter 8.

2.     WPCF  Manual of Practice No. 11, "Operation of Wastewater Treatment Plants,"
       1966.            "          "  "            .  \      	
3.     Wastewater Engineering,  Metcalf  and Eddy, McGraw-Hill. Book Company,  Inc.,
       1972.       „                  _"''_,-                   •-
                         - ,     .,  ..   :<.  ,  *'.*   .  t  .   '  ,,   ' ,  ,  .-
4.     McKinney,  Ross  E,,  Microbiology for Sanitary Engineers,  McGraw-Hill  Book
       Company, Inc., 1962, Chapter 23.
                                                                 „'"
5.     "A Study of  Sludge  Handling,and Disposal," U. S. Department of the Interior,
       Federal Water  Pollution Control Administration, Publication WP:20-4, May, 1968.
                     — -                      F  ••„-.     - i   ». „    *
6.     Standard Methods for the  Examination of  Wafer and Wastewater, 13th Edition,
       APHA, AWWA, WPCF, 1971.     :   ,  ,   ,   ^  „
                                          71

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SLUDGE CONDITIONING
A.     THICKENING  is  the process of  removing water  from  the  primary or
       secondary sedimentation tank sludge. The purpose of sludge thickening is to
       reduce the volume of the liquid sludge by increasing the concentration of the
       solids. This increases the solids holding capacity of the digester, reduces the
       heat requirement,  and  allows  the  digester  generally  to operate  more
       efficiently. The increase in solids content by thickening may be as much as
       100  percent. There are basically two  methods for thickening sludge  --  by
       gravity and by flotation.

       The  gravity thickener concentrates the sludge  by resettling much like  the
       settling tanks without mechanical rakes. Sludge removed from secondary
       settling tanks  usually   cannot  be  concentrated sufficiently  by gravity
       thickening alone.

       Gravity thickening with mechanical  rakes increases  the  efficiency of  the
       dewatering unit. Compaction  occurs  as a result of the compression due to
       the weight of the solids themselves and by the breaking up of the floe by the
       rakes, thereby  permitting  water to escape. This method is often used to
       handle sludge from the secondary settling tanks, due to the increase in solids
       concentration.

       Another method used to thicken sludge is through flotation. This procedure
       is basically the same as described in the start-up of the flotation units. (See
       Section III,  Start-Up   of the  Pretreatment, Primary  Treatment,  and
       Chlorination Facilities.) The process  involves the separation of solids from
       sludge   by  applying  air  under   pressure through the  sludge mass.  The
       flocculated sludge collects at  the surface of the aerated liquid where it is
       removed by collecting equipment.

       Inspection and Pretesting
       The  basin and piping  should be free of all debris. The drive motors, if used,
       should be checked for proper rotation,  drive  alignment,  clearances, noise,
       vibration,  and lubrication. The  weir  levels should be inspected and  made
       level. If a flotation thickener is used,  the air blower should be inspected and
       the air  lines checked  for leaks.  The diffusers  should be inspected for any
       defects  or  clogging  before  installation.  The  manufacturer's instructions
       should be on hand for guidance  in inspecting and pretesting the equipment.
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       Start-Up
       After the sludge  has  begun  to develop a blanket in the thickener,  the
       suspended solids (SS) and sludge volume index (SVI) should be determined.
       The  suspended solids will determine the thickener's efficiency and the SVI
       will aid in recognizing a bulking sludge. Sludge pumping should be stopped
       when the sludge appears thin.  The same problems that plague settling tanks
       occur in thickeners.  The  problems of bulking sludge, rising  sludge, and
       septicity are discussed under the Settling Tanks (Section III) of this manual.
       Chemical  coagulants  also  have been  used with thickeners  to aid  in  the
       densification of the sludge. Sludge should be withdrawn when it consists of
       4% -  8% dry solids as indicated by the total or suspended solids test or by
       visual observation. The laboratory  tests should be performed to verify the
       operator's judgment and for the plant's files.

B.     ELUTRIATION is a  unit  operation  having  the  dual function  of both
       conditioning and  thickening.  It is  a  washing process where  alkalinity is
       removed from the digested  sludge thereby  reducing chemical coagulant
       demand used for conditioning the sludge for dewatering.

       The mixing action  of the sludge with water is accomplished by mechanical or
       diffused air  agitation for a period of 1-2 minutes. The mixture of water and
       sludge is then settled  and the sludge is removed to  other  dewatering
       processes and  operations. The  supernatant is returned to another plant unit,
       usually the primary settling tank. Because this concentration of the solids in
       the sludge may be increased, this  process is  also  considered to act as a
       thickening unit.

       This process may remove up to  80  percent of the alkalinity and reduce the
       amount of ferric chloride used for conditioning the sludge by as much as 65
       to 80 percent.

       Inspection and Pretesting
       The  basin and piping should  be cleared of all debris and the drive  motors
       inspected for  secure  mounting,  rotation,  drive  alignment,  clearances,
       vibration, noise, and  lubrication. If an air blower is used, it should  also be
       inspected and the  air lines checked for leaks and the diffusers inspected for
       proper  operation.  The  manufacturer's  suggestions  for inspecting and
       pretesting the equipment should be followed also.
                                           73

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       Start-Up
       The alkalinity  of  the  sludge before  and  after  elutriation  should be
       determined. The alkalinity determination will provide a measure of the
       efficiency of the process by indicating the amount of alkalinity removed.
       This measure can be used to estimate the savings involved in reducing the
       amount of chemical conditioning used.

C.     CHEMICAL  CONDITIONING  is  usually  used  in advance  of vacuum
       filtration  or centrifugation as an aid in increasing the solids content of the
       sludge. Certain chemicals, alone or in combination, when added to raw or
       digested sludge result in the release of bound water and the formation of a
       relatively insoluble  floe  which  agglomerates  suspended  and  colloidal
       particles.  Chemicals  used  have included sulfuric acid, alum, chlorinated
       copper, ferrous sulfate, polymers, and, most commonly, ferric chloride, with
       or without lime.  Lime with ferric chloride is used to reduce the alkalinity of
       the sludge if other means such as elutriation are not used. Lime reduces the
       alkalinity by precipitating the bicarbonate alkalinity of the liquid portion of
       the sludge,  thereby  reducing the amount of ferric  chloride  needed to
       condition the sludge. The chemical dosage as determined in the laboratory is
       usually  mixed  with the sludge by mechanical means for 1 to 2 minutes
       before the sludge is dewatered.

       Inspection and Rretesting
       The mixing basin and piping should be cleared  of debris. The motors should
       be inspected for mounting, rotation, clearances, alignment, noise, vibration,
       and lubrication. The mixing action should be checked to see that it is mixing
       through  the  basin. The  chemical  metering system should be checked for
       proper calibration. All recorders should be checked for proper operation.

       Start-Up
       The mixers and recorders should be inspected periodically during start-up to
       see that they are functioning correctly.
SLUDGE DEWATERING
The most common methods of dewatering raw or digested sludge are by the use of drying
beds, vacuum filters and centrifuges.
                                           74

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A.     The SLUDGE DRYING BED dewaters digested sludge through evaporation
       and percolation. The  bed consists of an underdrain system, a course  of
       crushed rock and gravel, and a cover of 9 to 12 inches of sand. Some drying
       beds have glass covers to reduce environmental effects that would conflict
       with the operation of the drying bed and also reduce the required area for
       drying beds by reducing the time required for drying.

       Inspection and Pretesting
       The underdrain system should be cleared of debris. The sand layer should be
       inspected  for uniformity and raked smooth. The baffle should be placed
       correctly to ensure the sand is not washed out.

       Start-Up
       Before application  of  the digested sludge, the sand bed should be raked to
       loosen the compacted  sand. The bed should be  leveled and sludge admitted
       to a depth of approximately 12 inches.

       Sludge from the digester should not be drawn  too quickly, or coning may
       develop in the digester or the sand bed may be damaged.

       The sludge is dry when large cracks appear at the surface .and extend to the
       sand bed. The dried sludge may be removed by hand with a tine fork, shovel,
       or other appropriate equipment. As sludge is removed, some sand is lost and
       must  be replaced from time to time. Mechanical equipment, trucks, or any
       other equipment that would damage the sand bed should not be permitted
       on the beds, unless the design and construction of the beds provide for this
       contingency.

B.     VACUUM  FILTRATION is a  unit' operation  that usually requires  the
       addition of chemicals to assist in dewatering  the raw or digested sludge.
       After the chemical addition and mixing (to aid coagulation by the release of
       bound water), the sludge is ready to be withdrawn to the vacuum filter.

       Although there are a number of different types, the more common filter is a
       cylindrical  drum  with  some filter media  covering the  outside  surface.
       Internally the drum is divided into drainage compartments which connect to
       the  filtrate  system. Approximately  20  to 40  percent of the  drum is
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submerged in the filter "pan" which contains the sludge. The sludge mat is
formed on the filter surface as a result of a vacuum applied to the drainage
compartments that are in the submerged portion. As the mat rotates out of
the "pan," vacuum and dewatering are continuing. The cake is removed by
releasing the vacuum and applying  a  light air pressure to the inside of  the
filter, lifting the cake away from the filter where, with the aid of a scraper,
the cake is discharged into a hopper or onto a conveyor belt.

Some filters eliminate the scraper and air backblow by using coil springs as
the filter  media. The cake is discharged by the lifting action of the coils as
they leave the drum and travel to a discharge roller. The cake is discharged to
a hopper or conveyor belt as the coils pass around a return roller.

The vacuum filter, if operating and maintained correctly, should produce a 4
- 5 Ibs/sq  ft/hr of cake with a solids content of 20 to 40 percent for primary
sludge, and varies with the applied solids concentration.

Inspection and Pretesting
The supervisor should be on  hand when the unit is installed to see that it is
done according to the manufacturer's instructions and to note any problems
that arise  in the installation of the unit. The air and/or water lines should be
checked for leaks and all valves  cheeked for smooth and proper operation.
The unit should be lubricated and checked for clearances and alignment. The
motors should be inspected to see that they are rotating correctly, properly
lubricated,  aligned and create no undue noise  or vibration. The scraper
should be checked for clearance and alignment. Sludge and water withdrawal
system  should be checked.  The  filter media should be carefully checked
before installation and once again as the unit is put into operation to see it is
rotating smoothly without binding.

Start-Up
As the sludge begins entering  the vat, the  unit should be prepared  for
operation. When the sludge is at the proper depth, the unit should be turned
on and inspected frequently  for proper operation. The total yield, moisture
content, total solids,  and volatile solids of  the filtered sludge should be
determined  daily.  Other tests normally performed are  total solids, volatile
solids,  alkalinity  and  pH  before  the sludge  is  filtered.
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C.     CENTRIFUGATION separates the sludge solids from the liquid through
       sedimentation and  centrifugal force.  Chemical  addition  and mixing are
       sometimes used to render the process more effective in the dewatering of the
       sludge.

       Centrifuges are various sized cylinders that rotate at high speeds. The sludge
       is pumped to the center of the bowl where centrifugal force established by
       the rotating drum separates the lighter liquid from the denser solids. A screw
       conveyor inside  the drum removes the solid portion. The  liquid  portion is
       removed at  the  opposite end over adjustable weirs and usually returned to
       the thickener or primary clarifier. If operated and maintained correctly, the
       centrifuge should produce a cake of 30 to 35 percent solids.

       Inspection and Pretesting
       The installation  of  the centrifuge  should be checked to ensure it has been
       done in accordance with the  manufacturer's instructions and specifications.
       The alignment of the  unit's drum and screw conveyor should be inspected
       for proper clearances. The drive motor and coupling should be checked for
       proper alignment. See that the unit is properly lubricated and the lubricant
       recorded. Check the sound and vibration dumping to see that  it is installed
       correctly.

       Jog the mechanism through  one revolution listening for any unusual noise
       and look for any undue vibration. Check clearances,  drive alignment, and
       rotation.

       Start-Up
       As  waste begins  entering the bowl,  inspect the mechanism once again for
       proper operation. Run tests on moisture and percent solids before and after
       centrifugation in order to determine the efficiency of the centrifuge.

DISPOSAL
The principal methods of sludge disposal are: incineration, where the sludge cake is reduced
to an  ash  and the ash is spread on the land; lagooning, where the  sludge is allowed to
dewater naturally by percolation and evaporation, followed by removal  of the residue by
bulldozers  or  other  appropriate  methods; burial,  where  the  sludge  usually  contains
constituents which  render other methods impractical; land fill, where the sludge, either wet
or dewatered, is placed  on  fill and promptly covered with earth; soil conditioner, where the
                                           77

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sludge is spread on top of the surface for agricultural purposes; and ocean barging, where the
sludge is diluted in the ocean or other large bodies of water. For further information on the
subject of disposal see "A Study of Sludge Handling and Disposal," U. S. Department of the
Interior, Federal Water Pollution Control Administration, Publication WP-20-4, May, 1968.
                                           78

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                           SECTION VI
                          APPENDICES

APPENDIX                                                  PAGE

   A            ASSOCIATED EPA PROGRAMS                      81

   B            GLOSSARY          '                           83
                               79

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                          ASSOCIATED EPA PROGRAMS

The Environmental Protection Agency is developing several manuals to assist in the proper
operation and maintenance of municipal wastewater treatment plants. These manuals may
be useful in preparing for start-up.

A Planned Maintenance Management Program, Project No. 1101QGWI

Estimating  Staffing for  Municipal  Wastewater Treatment  Facilities,  Contract  No.
68-01r0328

Estimating Laboratory Needs for Municipal Wastewater Treatment Facilities, Contract No.
68-01-0328

Emergency  Operating Procedures for Municipal Wastewater Treatment Facilities, Contract
No. 68-01-0341

Maintenance  Management Systems  for  Municipal Wastewater  Facilities, Contract No.
68-01-0341

Emergency  Response Program for Municipal Wastewater Treatment Facilities - State and
Local Aspects, Contract No. 68-01-0341

Middle  Management  Concepts  for  Municipal Wastewater  Operations,  Contract  No.
68-01-0341 .    .

Procedural  Manual  for  Evaluating  the  Performance of Wastewater Treatment Plants,
Contract No. 68-01-0107

Safety in the Design, Operation and Maintenance of Wastewater Treatment Works, Contract
No. 68-01-0324
                                                                          »
Design Criteria for  Mechanical, Electric,  and  Fluid  System and Component  Reliability,
Contract No. 68-01-0001.

Methods for Chemical Analysis of Water and Waste, GPO Stock No. 5501-0067
                                                                  APPENDIX   A
                                         81

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                                   GLOSSARY

AEROBIC - Requiring or not destroyed by, the presence of free elemental oxygen.

AEROBIC BACTERIA -- Bacteria which will live and reproduce  only in an environment
       containing oxygen which  is  available for their  respiration such as atmospheric
       oxygen or oxygen dissolved in water.

ALGAE -- Primitive plants, one or many celled, usually aquatic, and capable of elaborating
       their foodstuffs by photosynthesis.
                                                      f
ALKALINITY (ALK) -- The capacity of water to neutralize acids, a property imported by
       the water's  content of carbonates,  bicarbonates, hydroxides,  and occasionally
       borates, silicates and phosphates.

ANAEROBIC --  Requiring, or not destroyed by, the absence of air or free (elemental)
       oxygen.

ANAEROBIC BACTERIA -  Bacteria which will live and reproduce in an environment
       containing no "free" or dissolved oxygen.

BACTERIA - A group  of universally distributed, rigid, essentially unicellular microscopic
       organisms lacking chlorophyll.

BOD - (1) Abbreviation for biochemical oxygen demand. The quantity of oxygen used in
       the«biochemical oxidation of organic matter in  a specified  time,  at a specified
       temperature, and under specified conditions. (2)  A standard test used in assessing
       waste water strength.

BOUND WATER -- Water strongly held on the surface of colloidal particles.

COAGULANTS - Chemicals added to destabilize, aggregate, and bind together colloids and
       emulsions to improve settleability, filterability, or drainability.

COD - Abbreviation for chemical oxygen demand.  A measure of the oxygen-consuming
       capacity of inorganic and organic matter present in water or wastewater. It does not
    •   differentiate  between stable  and  unstable  organic  matter  and thus  does not
       necessarily correlate with biochemical oxygen  demand.

                                           8g                         APPENDIX B
                                                                       Page 1 of 4

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DETENTION TIME -- The time required to fill a tank at a given flow or the theoretical time
       required for a given flow of wastewater to pass through a tank.

DO - Abbreviation  for dissolved oxygen. The oxygen dissolved in water, waste water, or
       other liquid.

EFFLUENT - Wastewater or other liquid which flows out of a basin, treatment process, or
       treatment plant.

BLUTRIATION -- A process of sludge  conditioning  whereby the sludge is washed with
       either fresh water or plant effluent to reduce the demand for conditioning chemicals
       and to improve settling or filtering characteristics of the solids.
           *
ENDOGENOUS - A diminished level of  respiration in  which materials previously stored by
       the cell are oxidized.

ENZYME -- A catalyst produced by living cells.

FACULTATIVE BACTERIA -- Bacteria which can adapt themselves  to growth in the
       presence, as well as in the absence of, elemental  oxygen.

FLOG  - Groups  of bacteria that have  joined together to form a cluster increasing the
       density where it will settle.

FUNGI - Small nonehlorophyll-bearing  plants which lack  roots, stems, or leaves,  which
       occur  (among other places) in water, wastewater, or wastewater effluents and grow
       best in the absence of light.

GRIT ~ The heavy suspended mineral matter present in  water or wastewater such as sand,
       gravel, and cinders.

INFLUENT -- Water, wastewater, or other liquid flowing into a  reservoir, basin, treatment
       process, or treatment plant.

INORGANIC MATTER ~ Chemical substances of mineral origin  which may contain carbon
       and oxygen.
                                                                    APPENDIX B
                                        84                         Page 2 of 4

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LIQUEFACTION - Liquefaction as applied to sludge digestion means the transformation of
       large solid particles of sludge into either a soluble or finely dispersed state.

MEDIA -- Rocks or other  material in a  trickling filter over which settled wastewater is
       sprinkled and then flows over and around during treatment. Slime organisms grow
       on the surface of the media and treat the wastewater.

MESOPHILIC  RANGE -- Operationally,  the temperature range most  conducive  to  the
       maintenance of optimum digestion by mesophilic bacteria, generally accepted as
       between 27° and 32° C (80° and 90° F.).
                                                                        /•
MIXED LIQUOR -- A mixture of activated sludge and organic matter undergoing activated
       sludge treatment in the aeration tank.

NITRIFICATION  -  The  biochemical  conversion  of  unoxidized  nitrogenous  matter
       (ammonia and organic nitrogen) to oxidized nitrogen (usually nitrate).

ORGANIC  MATTER  --  Chemical substances of  animal  or vegetable  origin,  or more
       correctly, of basically  carbon structure,  comprising  compounds consisting of
       hydrocarbons and  their derivatives.

ORGANISMS —  A form of life composed of mutually dependent parts that maintain various
       vital processes.

PATHOGENIC  ORGANISMS - Bacteria or viruses  which  can cause disease (typhoid,
       cholera, dysentery).

pH - A measure of the concentration by weight  of hydrogen ions, in grams, per liter of
       solution.  Neutral water, for example, has a pH of 7; acid water has a pH of less than
       7; and alkaline water has a pH of greater than 7.

PROPORTIONAL WEIR - A special type of weir in which the discharge through the weir is
       directly proportional to the head.

PROTOZOA -- Small one-celled animals.

SAPROPHYTIC  -- Living on dead or decaying matter.
                                                                    APPENDIX B
            .  .                                                        Page 3  of 4
             -     -                         85

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SETTLEABLE SOLIDS - (1) That matter in wastewater which will not stay in suspension
       during  a preselected  settling period, such  as one  hour, but either settles to  the
       bottom or floats to the top. (2) In the Imhoff cone test, the volume of matter that
       settles to the bottom of the cone in one hour.

SLOUGHINGS -- Trickling filter slimes that have been washed off the filter media.

SLUDGE - (1) The accumulated settleable solids separated from liquids,  such as water or
       wastewater,  during  processing.  (2)  The   precipitate resulting   from  chemical
       treatment, coagulation, or sedimentation of water or wastewater.

SLUDGE AGE — In the activated sludge process, a measure of the length  of time a particle
       of suspended solids has been undergoing aeration, expressed in days.

SLUDGE BLANKET - Accumulation of sludge hydrodynamically suspended within an
       enclosed body of wastewater.

SLUDGE BULKING - A  phenomenon that  occurs in  activated sludge plants where  the
       sludge occupies excessive volumes and will not concentrate readily.

SLUDGE VOLUME INDEX (SVI) -- The ratio of the volume in milliliters of sludge settled
       from a  1,000 ml  sample in  30 minutes to the dry-weight concentration of  the
       suspended solids in the mixed liquor in mg/1 and this ratio multiplied by 1,000.

SUSPENDED SOLIDS (SS)  -- The quantity of material removed  from wastewater in a
       laboratory test, as prescribed in "Standard Methods for the Examination  of Water
       and Wastewater" and referred to as nonfilterable residue.

THERMOPHILIC RANGE -  The temperature range most conducive  to  maintenance of
       optimum digestion  by thermophilic bacteria, generally accepted as between 120°
       and 135° F.

VOLATILE ACIDS (VA)  - Fatty acids containing six or less carbon atoms, which  are
       soluble in water and which can be steam-distilled at atmospheric pressure. Volatile
       acids are commonly reported as  equivalent to acetic acid.

VOLATILE SOLIDS (VS) - The quantity of solids in water,  wastewater, or other liquids,
       lost on ignition of the dry solids at 600° C.

ZOOGLEA - A jelly-like matrix developed by bacteria.
                                                                    APPENDIX B
                                         86                         Page  4 of 4

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                                 SECTION VII
                            ACKNOWLEDGEMENTS
The  data received  through personal communications  with  wastewater treatment plant
superintendents and  their staff,  consulting engineers, start-up experts, the academic
community,  manufacturers and suppliers of wastewater treatment plant equipment, and
EPA personnel is gratefully acknowledged.
                                        87

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                                 SECflONVm
                                 REFERENCES

 1.   Cassell, E. A. and Sawyer, C. N., "A Method for Starting High-Rate Digesters," Sewage
     and Industrial Wastes, Vol. 31, No. 2, p. 123 (February, 1959).

 2.   Caveriy, D.S., "Start-up of New Wastewater Treatment Plants," Journal WPCF, Vol. 40,
     No. 4, p. 571 (April, 1968).

 3.   "Chlorine Manual," 4th edition, The Chlorine Institute, Inc. (December, 1972).

 4.   Dague, Richard R., "Application of Digestion Theory to Digester  Control," Journal
     WPCF, Vol. 40, No. 12, p. 2021 (December, 1968).

 5.   Eckenfielder, A. W. and O'Conner, D. J., Biological Waste Treatment, Pergamon Press,
     1961.

 6.   "Estimating  Costs  and Manpower  Requirements  for  .Conventional Wastewater
     Treatment Facilities," EPA, Contract No. 14-12-462, October, 1971.

 7.   Filbert, J. W., "Procedures and Problems of Digester Start-Up," Journal WPCF, Vol. 39,
     No. 3, p. 367 (March, 1967).

 8.   "Glossary  of  Water  and  Wastewater Control Engineering," APHA, ASCE, AWWA,
     WPCF, 1969.

 9.   Hatfield, W. D., "Operation of the Activated Sludge Process," Journal WPCF, Vol. 38,
     No. 6, p. 957 (June, 1966).

10.   Hicks, C., "Digester Start-up at Cobourg, Ontario," Sewage and Industrial Wastes, Vol.
     31, No. 1, p. 117 (January, 1959).

11.   Keteham,  L., "Operator Ingenuity at the  Tacoma, Washington, Sewage Treatment
     Plant," Sewage and Industrial Wastes, Vol. 30, No. 12, p. 1506 (December, 1958).

12.   Kfer, L. D., "Start-up  Problems at a Metropolitan District Plant," Journal WPCF, Vol.
     40, No. 7, p. 1338 (July, 1968).
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13.   Kugelman, L  J. and  McCarty, P. L., "Cation Toxicity in Stimulation in Anaerobic
      Waste Treatment," Journal WPCF, Vol. 37, No. 1, p. 97 (January, 1965).

14.   Lohmeyer, G. T., "A Review of Sludge Digestion," Journal WPCF, Vol. 31, No. 2, p.
      221 (February, 1959).

15.   Lynam,  B., McDonnell, G.,  and Rrup, M.,  "Start-up and Operation of Two New
      High-Rate Digestion Systems," Journal  WPCF, Vol. 39, No. 4, p. 518 (April, 1967).

16.   McCarty, P. L. and McKinney, R. E., "Salt Toxicity in Anaerobic Digestion," Journal
      WPCF, Vol. 33, No. 4, p. 399 (April, 1961).

17.   McCarty, P. L. and McKinney, R. E., "Volatile Acid Toxicity in Anaerobic Digestion,"
      Journal WPCF, Vol. 33, No. 3, p. 223 (March, 1961).

18.   McKinney, Ross E., Microbiology for Sanitary Engineers, McGraw-Hill Book Company,
      1962.

19.   Manual  of Instruction  for Sewage Treatment Plant  Operators, New York State
      Department of Health.

20.   Manual of Wastewater Operations, Texas Water Utilities Association, 1971.

21.   Metcalf  &  Eddy, Inc.,  Wastewater Engineering, McGraw-Hill Book  Company, Inc.,
      1972.

22.   "Operation and  Maintenance  Manual, Wastewater  Stabilization Lagoon  and Lift
      Station," Culver Engineering, August 24,1972.

23.   "Operations of Wastewater Treatment Plants," Sacramento State College, Department
      of Civil Engineering.

24.   "Plant Start-Up Procedure," Ontario Water Resources Commission, Division of Plant
      Operations, July, 1968.

25.   Pohlard, F. G. and Ghosh, S., "Developments in Anaerobic Treatment Processes,"
      Biotechnical and Bioengineering, Symposium No. 2, p. 85 (1971).
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26.   "Procedural Manual for Evaluating the Performance of Wastewater Treatment Plants,"
      EPA, Contract No.  68-01-0107, Standard'Methods, 13th edition, American Public
      Health Association, 1971.
                                          " ^   '          '  „    *          . ^
27.   Recommended Standards for Sewage Works, Great Lakes - Upper Mississippi River
      Board of State Sanitary Engineers, Health Education Service, Albany, New York.

28.   "Safety  Regulations," 3rd edition,  Ontario Water Resources Commission, Division of
      Plant Operations, 1971.

29.   Schlenz,  H.  E.,  "Important  Considerations in Sludge Digestion. Part I -  Practical
      Aspects," Sewage Works Journal, Vol. XIX, No. 1, p. 19 (January, 1947).

30.   Schlenz, H. E., "Sludge Digestion - 1957  Operators Forum," Sewage  and Industrial
      Wastes, Vol. 30, No. 4, p. 585 (April, 1958).

31.   "Sewage Treatment Plant Manual," 2nd edition, OWRC, Division of Plant Operations,
      1972.

32.   Shafer, S. W., "Initial Digester Start-up at Alexandria, Virginia," Sewage and Industrial
      Wastes, Vol. 29 No. 10, p. 1190 (October, 1957).

33.   Standard'Methods for the Examination of Water and Wastewater, 13th edition, APHA,
      AWWA, WPCF, 1971.

34.   "A Study of Sludge Handling and Disposal," U. S. Department of the Interior, Federal
      Water Pollution Control Administration, Publication No. WP-20-4, May, 1968.

35.   Van  Kleek, L. W.,  "Start-up of Separate Sludge Digesters," Sewage  and Industrial
      Wastes, Vol. 30, No. 3, p. 312 (March, 1958).

36.   West, A. W., PE, "Activated Sludge Process Operational Control," May, 1971.

37.   West, A. W.,  PE, "Preliminary Report on Start-up of the Activated Sludge Process at
      the  Lower Potomac Water Pollution Control Plant at Fairfax County, Virginia,"
      February, 1971.
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38.   Wittenburg,  John  A.,  "Hlot  Study  .to Determine  Manpower  Requirements  for
      Conventional Sewage Treatment Plants," Manpower and Training Division, Federal
      Water Quality Administration, September, 1970.

39.   WPCF Manual of Practice No. 1, "Safety in Wastewater Works," 1967,

40.   WPCF Manual of Practice No. 11, "Operation of Wastewater Treatment Plants," 1966.

41.   WPCF Manual of Practice No. 16, "Anaerobic Sludge Digestion," 1968.

42.   White, George C., Handbook of Chlorination, Van Nostrand Reinhold Company, 1972.
                                        U S GOVERNMENT PRINTING OFFICE 1980— 677-121/047 REGION NO 8
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