v>EPA
                       United States
                       Environmental Protection
                       Agency
                       Office of Water
                       Washington, D.C.
EPA 932-F-99-073
September 1999
Waste water
Technology  Fact Sheet
Sequencing  Batch  Reactors
DESCRIPTION

The sequencing batch reactor (SBR) is a fill-and-
draw  activated sludge system for wastewater
treatment. In this system, wastewater is added to a
single  "batch"  reactor,   treated  to  remove
undesirable  components,  and  then  discharged.
Equalization, aeration, and clarification can all be
achieved using a single batch reactor. To optimize
the performance of the system, two or more batch
reactors are used in a predetermined sequence of
operations.  SBR systems  have been successfully
used  to  treat  both  municipal  and  industrial
wastewater.     They  are   uniquely  suited  for
wastewater treatment applications characterized by
low or intermittent flow conditions.

Fill-and-draw batch processes similar to the SBR
are not a recent development as commonly thought.
Between 1914 and 1920, several full-scale fill-and-
draw systems were in operation.  Interest in SBRs
was revived in the late 1950s and early 1960s, with
the development of new equipment and technology.
Improvements in aeration devices and controls have
allowed SBRs to  successfully  compete  with
conventional activated sludge systems.

The unit processes of the  SBR and conventional
activated sludge systems are the same. A 1983 U.S.
EPA report, summarized this by stating that "the
SBR is no more than an activated sludge system
which operates in time rather than in space." The
difference between the two technologies is that the
SBR performs equalization, biological treatment,
and secondary clarification in a single tank using a
timed control sequence. This type of reactor does,
in some cases, also perform primary clarification. In
a conventional activated sludge system, these unit
                      processes would be accomplished by using separate
                      tanks.

                      A modified version of the SBR is the Intermittent
                      Cycle Extended Aeration System (ICEAS). In the
                      ICEAS system, influent wastewater flows into the
                      reactor on a continuous basis.  As such, this is not
                      a true batch reactor, as is the conventional SBR. A
                      baffle wall may be used in the ICEAS to buffer this
                      continuous inflow. The design configurations of the
                      ICEAS and the SBR are otherwise very similar.

                      Description of a Wastewater Treatment Plant
                      Using an SBR

                      A typical process flow schematic for a municipal
                      wastewater treatment plant using an SBR is shown
                      in Figure 1.  Influent wastewater generally passes
                      through screens and grit removal prior to the SBR.
                      The wastewater then enters a partially filled reactor,
                      containing biomass, which  is acclimated to the
                      wastewater constituents  during preceding cycles.
                      Once  the  reactor  is  full,  it behaves  like a
                      conventional activated sludge system, but without a
                      continuous influent or effluent flow.  The aeration
                      and mixing is discontinued  after the biological
                      reactions are complete, the biomass settles, and the
                      treated supernatant is removed. Excess biomass is
                      wasted at any time during the cycle.  Frequent
                      wasting results in holding the mass ratio of influent
                      substrate to biomass nearly constant from cycle to
                      cycle. Continuous flow systems hold the mass ratio
                      of influent  substrate to  biomass  constant by
                      adjusting return   activated  sludge   flowrates
                      continually as influent flowrates, characteristics, and
                      settling tank underflow concentrations vary. After
                      the SBR, the "batch" of wastewater may flow to an
                      equalization basin where the wastewater flowrate to

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additional unit processed can be is controlled at a
determined rate. In some cases the wastewater is
filtered  to remove  additional solids and  then
disinfected.

As illustrated in Figure 1, the solids handling system
may consist of a thickener and  an aerobic digester.
With  SBRs there is no need for  return activated
sludge (RAS)  pumps  and primary  sludge  (PS)
pumps like those associated  with conventional
activated sludge systems.  With the SBR, there is
typically only one sludge to handle. The need for
gravity thickeners prior to digestion is determined
               TO SOLIDS HANDLING,
                 DISPOSAL, OR
               BENEFICIAL REUSE
         SCREENING/   SBR  EQUALIZATION FILTRATION DISINFECTION
          GRINDING
Source: Parsons Engineering Science, 1999.

   FIGURE 1 PROCESS FLOW DIAGRAM
            FOR A TYPICAL SBR

on  a  case  by case  basis  depending  on  the
characteristics of the sludge.
An SBR serves as an equalization basin when the
vessel is filling with wastewater, enabling the system
to tolerate peak flows or peak loads in the influent
and to equalize them in the batch reactor.  In many
conventional  activated sludge  systems,  separate
equalization is needed to protects the biological
system from peak flows, which may wash out the
biomass, or  peak loads,  which  may upset the
treatment process.

It should also be noted that primary clarifiers are
typically not  required  for  municipal  wastewater
applications prior to an SBR. In most conventional
activated  sludge wastewater  treatment  plants,
primary clarifiers are used prior to the biological
system.   However, primary  clarifiers may  be
recommended by the SBR manufacturer if the total
suspended  solids (TSS)  or biochemical oxygen
demand (BOD) are greater than 400 to 500 mg/L.
Historic data should be  evaluated and the  SBR
manufacturer consulted   to determine whether
primary clarifiers or equalization are recommended
prior  to an  SBR  for municipal  and  industrial
applications.

Equalization  may be  required  after  the  SBR,
depending  on   the  downstream  process.    If
equalization is not used prior to filtration, the filters
need to be sized in order to receive  the batch of
wastewater from the SBR, resulting in a large
surface area required for filtration. Sizing filters to
accept these "batch" flows is usually not feasible,
which is why equalization is used between an SBR
and downstream filtration.  Separate equalization
following  the biological  system is generally not
required for  most conventional  activated  sludge
systems, because the flow is on a continuous and
more constant basis.

APPLICABILITY

SBRs are typically used at flowrates of 5 MOD or
less. The more sophisticated operation required at
larger SBR plants tends to discourage the use of
these plants for large flowrates.

As these systems have a relatively small footprint,
they are useful for areas where the available land is
limited. In addition, cycles within the system can be
easily modified  for nutrient removal in the future, if
it becomes necessary. This makes SBRs extremely
flexible to adapt to regulatory changes for effluent
parameters such as nutrient removal. SBRs are also
very cost effective if treatment beyond biological
treatment is required, such as filtration.

ADVANTAGES AND DISADVANTAGES

Some advantages and disadvantages  of  SBRs are
listed below:

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Advantages

•  Equalization,  primary  clarification (in most
   cases), biological  treatment,  and  secondary
   clarification can be achieved in a single reactor
   vessel.

•  Operating flexibility and control.

•  Minimal footprint.

•  Potential  capital cost savings by  eliminating
   clarifiers and other equipment.

Disadvantages

•  A  higher  level  of  sophistication  is required
   (compared to conventional systems), especially
   for larger systems, of timing units and controls.

•  Higher level of maintenance  (compared  to
   conventional  systems)  associated  with more
   sophisticated controls, automated switches, and
   automated valves.

•  Potential of discharging floating or settled sludge
   during the DRAW or decant phase with some
   SBR configurations.

•  Potential  plugging of aeration devices during
   selected operating cycles,  depending  on  the
   aeration system used by the manufacturer.

•  Potential requirement for equalization after the
   SBR, depending on the downstream processes.

DESIGN CRITERIA

For any wastewater treatment plant design, the first
step is  to  determine  the  anticipated  influent
characteristics of the wastewater and  the effluent
requirements  for the  proposed  system.    These
influent parameters typically include design flow,
maximum daily flow BOD5, TSS, pH, alkalinity,
wastewater temperature, total Kjeldahl nitrogen
(TKN),  ammonia-nitrogen  (NH3-N),  and total
phosphorus  (TP).   For industrial and  domestic
wastewater, other site specific parameters may also
be required.
The state regulatory agency should be contacted to
determine the effluent requirements of the proposed
plant. These effluent discharge parameters will be
dictated by the state in  the National  Pollutant
Discharge Elimination System  (NPDES)  permit.
The parameters typically permitted for municipal
systems are  flowrate,  BOD5,  TSS,  and Fecal
Coliform.   In addition,  many states are moving
toward requiring nutrient removal. Therefore, total
nitrogen (TN),  TKN,  NH3-N, or TP may  also be
required.   It is imperative to  establish effluent
requirements because they will impact the operating
sequence of the SBR.  For example, if there is a
nutrient  requirement  and NH3-N  or  TKN is
required, then nitrification will be necessary.  If
there  is  a  TN  limit,   then  nitrification  and
denitrification will be necessary.

Once the influent and effluent characteristics of the
system are  determined, the engineer will typically
consult  SBR manufacturers for a recommended
design. Based on these parameters, and  other site
specific parameters such as temperature, key design
parameters are selected for the system. An example
of these parameters for a wastewater system loading
is listed in Table 1.

  TABLE 1  KEY DESIGN PARAMETERS
      FOR A CONVENTIONAL LOAD

                     Municipal     Industrial

 Food to Mass (F:M)     0.15 - 0.4/day      0.15-
                                    0.6/day
 Treatment Cycle
 Duration
4.0 hours
4.0-24
 hours
 Typically Low Water    2,000-2,500    2,000-4,000
 Level Mixed Liquor        rng/L          rng/L
 Suspended Solids

 Hydraulic Retention     6-14 hours       varies
 Time	

 Source: AquaSBR Design Manual, 1995.
Once the key design parameters are determined, the
number of cycles per day, number of basins, decant
volume, reactor size, and detention times can  be
calculated.   Additionally, the aeration equipment,
decanter, and associated piping can then be sized.

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Other site specific information is needed to size the
aeration  equipment, such as site elevation  above
mean sea level, wastewater temperature, and total
dissolved solids concentration.

The operation of an SBR is based on the fill-and-
draw principle, which consists of the following five
basic  steps: Idle, Fill,  React,  Settle,  and  Draw.
More than one operating strategy is possible  during
most  of these  steps.  For industrial  wastewater
applications,  treatability   studies  are  typically
required to  determine  the optimum  operating
sequence.    For  most  municipal   wastewater
treatment plants, treatability studies are not required
to  determine  the  operating  sequence  because
municipal wastewater flowrates and characteristic
variations  are  usually  predictable  and   most
municipal designers will follow conservative  design
approaches.

The Idle step occurs between the Draw and the Fill
steps, during which treated effluent is removed and
influent wastewater is added.  The length of the Idle
step varies depending on the influent flowrate and
the operating strategy.  Equalization  is achieved
during this  step  if variable  idle times  are used.
Mixing to condition the biomass and sludge wasting
can  also be  performed   during the  Idle step,
depending on the operating strategy.

Influent wastewater is added to the reactor  during
the Fill step.  The  following three variations are
used for the Fill step and any or all of them may be
used depending on the operating strategy: static fill,
mixed fill, and aerated fill.  During static fill, influent
wastewater is added to the biomass already present
in the SBR.  Static fill is characterized by no mixing
or aeration,  meaning  that there will be a high
substrate (food) concentration when mixing begins.
A high food to microorganisms (F:M) ratio creates
an environment favorable to floe forming organisms
versus filamentous organisms, which provides good
settling characteristics for the sludge. Additionally,
static fill conditions favor organisms that produce
internal  storage  products during high  substrate
conditions, a requirement for biological phosphorus
removal.  Static  fill may be compared to using
"selector" compartments in a conventional activated
sludge system to  control the F:M ratio.
Mixed fill is classified by mixing influent organics
with  the  biomass,  which  initiates  biological
reactions. During mixed fill, bacteria biologically
degrade  the organics and use residual  oxygen or
alternative electron acceptors,  such  as nitrate-
nitrogen.  In this environment, denitrification may
occur under these anoxic conditions. Denitrification
is the biological  conversion of nitrate-nitrogen to
nitrogen  gas. An anoxic condition is defined as an
environment in which oxygen is not present and
nitrate-nitrogen is used by the microorganisms as
the electron acceptor. In a conventional biological
nutrient  removal (BNR) activated sludge system,
mixed fill is comparable to the anoxic zone which is
used for  denitrification.  Anaerobic conditions can
also be achieved during the mixed fill phase. After
the microorganisms use the nitrate-nitrogen, sulfate
becomes  the  electron   acceptor.     Anaerobic
conditions are characterized by the lack of oxygen
and sulfate as the electron acceptor.

Aerated Fill is classified by aerating the contents of
the reactor to begin the aerobic reactions completed
in  the React step.  Aerated Fill  can reduce the
aeration time required in the React step.

The biological reactions are completed in the React
step, in which mixed react and aerated react modes
are available.   During aerated react, the aerobic
reactions initialized during aerated fill are completed
and nitrification can be achieved.  Nitrification is the
conversion of ammonia-nitrogen to nitrite-nitrogen
and ultimately to nitrate-nitrogen. If the mixed react
mode is selected, anoxic conditions can be attained
to achieve denitrification. Anaerobic conditions can
also be  achieved in the mixed react  mode for
phosphorus removal.

Settle  is  typically  provided  under   quiescent
conditions in the SBR. In some cases, gentle mixing
during the initial stages of settling may result in a
clearer effluent  and a more concentrated settled
sludge. In an SBR, there are no influent or effluent
currents to interfere with the settling process as in a
conventional activated sludge system.

The Draw step  uses  a  decanter to remove the
treated effluent, which is the primary distinguishing
factor between different SBR manufacturers.  In
general,  there  are floating decanters  and fixed

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decanters.    Floating   decanters  offer  several
advantages over fixed decanters as described in the
Tank and Equipment Description Section.

Construction

Construction of SBR systems can typically require
a smaller  footprint  than  conventional activated
sludge systems because the SBR often eliminates the
need for primary clarifiers.  The SBR never requires
secondary clarifiers.  The size of the SBR tanks
themselves will be site specific, however the SBR
system is  advantageous  if space  is limited  at the
proposed site. A few case studies are presented in
Table 2 to provide  general  sizing  estimates  at
different flowrates. Sizing of these systems  is site
specific and these case studies do not  reflect every
system at that size.

 TABLE 2  CASE STUDIES FOR  SEVERAL
           SBR INSTALLATIONS
Flow
(MGD)
0.012
0.10
1.2
1.0
1.4
1.46
2.0
4.25
5.2
Reactors
No.
1
2
2
2
2
2
2
4
4
Size
(feet)
18x12
24x24
80x80
58x58
69x69
78x78
82x82
104x80
87x87
Volume
(MG)
0.021
0.069
0.908
0.479
0.678
0.910
0.958
1.556
1.359
Blowers
No.
1
3
3
3
3
4
3
5
5
Size
(HP)
15
7.5
125
40
60
40
75
200
125
Note: These case studies and sizing estimates were provided
by Aqua-Aerobic Systems,  Inc. and are  site specific to
individual treatment systems.

The  actual  construction of  the  SBR tank and
equipment may be comparable  or simpler than a
conventional activated   sludge  system.    For
Biological Nutrient Removal (BNR) plants, an SBR
eliminates the need  for  return activated  sludge
(RAS) pumps and pipes.  It may also eliminate the
need for internal Mixed Liquor Suspended Solid
(MLSS)  recirculation, if this is being used in a
conventional BNR system to return nitrate-nitrogen.
The control system of an SBR operation is more
complex than  a conventional activated  sludge
system and includes automatic switches, automatic
valves, and instrumentation.  These  controls are
very sophisticated in  larger systems.  The  SBR
manufacturers indicate that most SBR installations
in the United States are used for smaller wastewater
systems of less than two million gallons per day
(MGD) and some references recommend SBRs only
for small communities where land is limited. This is
not always the case, however, as the largest SBR in
the world is currently a  10  MGD system in the
United Arab Emirates.

Tank and Equipment Description

The SBR  system consists of a tank,  aeration and
mixing equipment, a decanter, and a control system.
The central features of the SBR system include the
control unit and the automatic switches and valves
that sequence and time the different operations.
SBR  manufacturers  should  be  consulted  for
recommendations on tanks  and equipment.  It is
typical to use a complete SBR system recommended
and supplied by  a single SBR manufacturer.  It is
possible, however, for an engineer to design an SBR
system, as  all   required  tanks,  equipment, and
controls   are   available   through  different
manufacturers.    This is not typical  of  SBR
installation because of the level of sophistication of
the instrumentation and controls associated with
these systems.

The SBR tank is typically constructed with steel or
concrete.  For industrial  applications, steel tanks
coated for corrosion  control are most  common
while concrete  tanks  are the  most common for
municipal treatment of domestic wastewater. For
mixing and aeration, jet aeration systems are typical
as they allow mixing either with or without aeration,
but other aeration and mixing systems are also used.
Positive displacement blowers are typically used for
SBR design to handle wastewater level variations in
the reactor.

As  previously  mentioned, the  decanter  is  the
primary piece  of equipment that distinguishes
different SBR manufacturers.  Types of decanters
include floating and fixed. Floating  decanters offer
the advantage of maintaining the inlet orifice slightly

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below the water surface to minimize the removal of
solids in the effluent removed during  the DRAW
step.  Floating decanters also offer the operating
flexibility to vary  fill-and-draw volumes.   Fixed
decanters are built into the side of the basin and can
be used if the Settle step is extended. Extending the
Settle step minimizes the chance that solids in the
wastewater will float over the fixed decanter.  In
some cases, fixed decanters are less expensive and
can be designed to allow the  operator to lower or
raise the level  of the decanter.  Fixed decanters do
not offer the operating  flexibility of the floating
decanters.

Health and  Safety

Safely  should be  the primary concern in every
design  and system operation.  A properly designed
and operated system will minimize potential health
and safety concerns. Manuals such as the Manual of
Practice  (MOP)  No.  8,  Design  of  Municipal
Wastewater  Treatment Plants, and MOP No. 11,
Operation of  Municipal Wastewater  Treatment
Plants should be consulted to minimize these risks.
Other appropriate industrial wastewater treatment
manuals, federal regulations, and state regulations
should  also be consulted for  the design  and
operation of wastewater treatment systems.

PERFORMANCE

The performance of SBRs is typically comparable to
conventional activated sludge systems and depends
on  system  design  and  site specific  criteria.
Depending on their mode of operation, SBRs can
achieve good  BOD and nutrient removal.   For
SBRs,  the BOD removal efficiency is generally 85
to 95 percent.

SBR manufacturers will typically provide a process
guarantee to produce an effluent of less than:

•  lOmg/LBOD

•  10 mg/L TSS

•  5-8 mg/L TN

•  1-2 mg/L TP
OPERATION AND MAINTENANCE

The SBR typically eliminates the need for separate
primary and secondary clarifiers in most municipal
systems, which reduces operations and maintenance
requirements.  In addition, RAS pumps  are  not
required.    In conventional  biological  nutrient
removal systems, anoxic basins, anoxic zone mixers,
toxic basins, toxic basin aeration equipment, and
internal MLSS nitrate-nitrogen recirculation pumps
may  be necessary.   With the  SBR, this can be
accomplished in  one reactor using aeration/mixing
equipment,  which  will  minimize  operation  and
maintenance requirements otherwise be needed for
clarifiers and pumps.

Since the heart of the SBR system is the controls,
automatic valves, and  automatic switches, these
systems may  require more  maintenance than  a
conventional activated sludge system. An increased
level of sophistication usually equates to more items
that can fail or require maintenance.  The level of
sophistication may be very advanced in larger SBR
wastewater treatment plants requiring a higher level
of maintenance  on the  automatic valves  and
switches.

Significant operating flexibility  is associated with
SBR systems.  An SBR can be  set up to  simulate
any conventional activated sludge process, including
BNR systems. For  example, holding times in the
Aerated React mode of an SBR can be varied to
achieve simulation of a contact stabilization system
with a typical hydraulic retention time (HRT) of 3.5
to 7 hours or, on the other end of the spectrum, an
extended aeration treatment system with a typical
HRT of 18 to 36 hours.  For  a BNR plant, the
aerated react mode (oxic conditions) and the mixed
react modes (anoxic conditions) can be alternated to
achieve nitrification  and denitrification. The mixed
fill mode  and  mixed react mode can be used to
achieve denitrification using anoxic conditions. In
addition, these modes can ultimately be used to
achieve an anaerobic condition  where phosphorus
removal can occur.  Conventional activated sludge
systems typically require additional tank volume to
achieve such flexibility.  SBRs operate in time rather
than in space and the number of cycles per day can
be varied to control desired effluent limits, offering
additional  flexibility with an SBR.

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COSTS

This section includes some general guidelines  as
well as some general cost estimates for planning
purposes. It should be remembered that capital and
construction cost estimates are site-specific.

Budget level cost estimates presented in Table 3 are
based on projects that occurred from 1995 to 1998.
Budget level  costs include such  as the blowers,
diffusers, electrically operated valves, mixers, sludge
pumps, decanters, and the control panel.  All costs
have been updated to March 1998 costs, using  an
ENR construction cost index of 5875  from the
March 1998 Engineering News Record, rounded off
to the nearest thousand dollars.

    TABLE 3 SBR EQUIPMENT COSTS
    BASED ON DIFFERENT PROJECTS
    Design Flowrate
        (MGD)
   Budget Level
Equipment Costs ($)
0.012
0.015
1.0
1.4
1.46
2.0
4.25
94,000
137,000
339,000
405,000
405,000
564,000
1,170,000
 Source: Aqua Aerobics Manufacturer Information, 1998.
In Table 4, provided a range of equipment costs for
different design flowrates is provided.
                          TABLE 4 BUDGET LEVEL EQUIPMENT
                          COSTS  BASED ON DIFFERENT FLOW
                                           RATES
                          Design Flowrate
                              (MGD)
                    Budget Level Equipment
                           Costs ($)
                                 1

                                 5

                                10

                                15

                                20
                        150,000-350,000

                        459,000 - 730,000

                       1,089,000-1,370,000

                           2,200,000

                       2,100,000-3,000,000
Note: Budget level cost estimates provided by Babcock King -
Wilkinson, L.P., August 1998.

Again the equipment cost items provided do  not
include  the  cost  for  the   tanks,   sitework,
excavation/backfill,  installation,  contractor's
overhead  and profit,  or  legal, administrative,
contingency, and engineering services. These items
must  be  included  to  calculate  the  overall
construction costs of an SBR system.  Costs  for
other  treatment  processes, such  as  screening,
equalization,  filtration,  disinfection,  or  aerobic
digestion, may be included if required.

The ranges of construction costs for a complete,
installed SBR wastewater treatment  system  are
presented in Table 5. The variances in the estimates
are due to the type of sludge handling facilities and
the differences in newly constructed plants versus
systems that use existing plant facilities.  As such, in
some cases these estimates include other processes
required in an SBR wastewater treatment plant.

     TABLE 5 INSTALLED COST PER
  GALLON OF WASTEWATER TREATED
                                                    Design Flowrate
                                                        (MGD)
                                                   Budget Level
                                                 Equipment Cost
                                                    ($/gallon)
                                                        0.5-1.0

                                                        1.1 -1.5

                                                        1.5-2.0
                                                     1.96-5.00

                                                     1.83-2.69

                                                     1.65-3.29
                                                Note: Installed cost estimates obtained from Aqua-Aerobics
                                                Systems, Inc., August 1998.

                                                There is typically an economy of scale associated
                                                with construction costs for wastewater treatment,

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meaning that larger treatment plants can usually be
constructed at a lower cost per gallon than smaller
systems. The use of common wall construction for
larger treatment systems, which can be used for
square or rectangular SBR reactors, results in this
economy of scale.

Operations   and  Maintenance  (O&M)   costs
associated with an SBR system may be similar to a
conventional activated sludge system. Typical cost
items associated with wastewater treatment systems
include labor,  overhead, supplies,  maintenance,
operating administration, utilities, chemicals, safety
and training, laboratory testing, and solids handling.
Labor  and  maintenance  requirements may  be
reduced in SBRs because  clarifiers, clarification
equipment, and RAS pumps may not be necessary.
On the other hand, the maintenance requirements
for the automatic valves and switches that control
the sequencing may  be more intensive than for a
conventional activated sludge system. O&M costs
are site specific and may range from $800 to $2,000
dollars per million gallons treated.

REFERENCES

1.     AquaSBR Design Manual. Mikkelson, K. A.
      of Aqua-Aerobic Systems. Copyright 1995.

2.     Arora, Madan L. Technical Evaluation of
      Sequencing Batch Reactors.  Prepared for
      U.S. EPA. U.S. EPA Contract No. 68-03-
       1821.
7.      Metcalf   &   Eddy,   Inc.   Wastewater
       Engineering: Treatment, Disposal, Reuse.
       3rd edition. New York:  McGrawHill.

8.      Parsons Engineering Science, Inc. Basis of
       Design Report  -  Urgent Extensions to
       Moray Sewer Treatment Works, Abu Dhabi,
       UAE,  1992.

9.      Norcross, K.L., Sequencing Batch Reactors
       - An Overview.  Technical Paper published
       in the IAWPRC  1992  (0273-1221/92).
       Wat.  Sci. Tech., Vol. 26, No.  9-11, pp.
       2523 - 2526.

10.    Peavy,   Rowe,   and   Tchobanoglous:
       Environmental Engineering.  New York:
       McGraw-Hill, Inc.

11.    U.S.  EPA.   Innovative  and Alternative
       Technology  Assessment  Manual,
       EPA/430/9-78-009. Cincinnati, Ohio, 1980.

12.    U.S. EPA. EPA Design Manual, Summary
       Report  Sequencing  Batch  Reactors.
       EPA/625/8-86/011, August 1986.

13.    Manual of Practice (MOP) No. 8, Design of
       Municipal Wastewater Treatment Plants,

14.    Manual  of  Practice  (MOP)  No.  11,
       Operation  of  Municipal  Wastewater
       Treatment Plants.
      Engineering News-Record. A publication of
      the McGraw  Hill Companies,  March 30,
       1998.

      Irvine, Robert L. Technology Assessment of
      Sequencing Batch Reactors.  Prepared for
      U.S. EPA. U.S. EPA Contract No. 68-03-
      3055.

      Liu, Liptak,  and Bouis.   Environmental
      Engineer's Handbook, 2nd edition.   New
      York: Lewis Publishers.

      Manufacturers  Information.     Aqua-
      Aerobics, Babcock King-Wilkinson,  L.P.,
      Fluidyne, and Jet Tech Systems, 1998.
ADDITIONAL INFORMATION

Brad Holtsinger, Chief Operator
City of Stockbridge WWTP
4545 North Henry Boulevard
Stockbridge, GA 30281

Gary Hooder, Operator
Martinsburg WWTP
133 East Allegheny
Martinsburg, PA 16662-1112

Mitchell Meadows, Lead Operator
13 00 Recker Highway
Auburndale, FL 33823

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Teresa Schnoor, Administrator
Antrim TWP
P.O.Box 130
Greencastle, PA 17225

Charles Sherrod, Chief Operator
Blountstown WWTP
125 West Central Avenue
Blountstown, FL 32424

The mention of trade names or commercial products
does not constitute endorsement or recommendation
for  use  by  the U.S. Environmental Protection
Agency.
                                                         For more information contact:

                                                         Municipal Technology Branch
                                                         U.S. EPA
                                                         Mail Code 4204
                                                         401 M St., S.W.
                                                         Washington, D.C., 20460


                                                         IMTB
                                                         Exceience fh compliance through optftnal technical sotrtroru:
                                                         MUNICIPAL TECHNOLOGY

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