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Environmental Protection Agency
Technology Transfer Program
Upgrading Poultry Processing
Facilities to Reduce Pollution
Treatment for Discharge to a Stream
Industry Seminar for
Pollution Control
Little Rock, Arkansas
January 16,17,18,1973
Giffels Associates, Inc
Architects Engineers Planners
Detroit, Michigan
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UPGRADING POULTRY PROCESSING FACILITIES
TO REDUCE POLLUTION
TREATMENT FOR DISCHARGE TO A STREAM
TECHNOLOGY TRANSFER INDUSTRY SEMINAR
LITTLE ROCK, ARKANSAS
JANUARY 16, 17, 18, 1973
Prepared for the
ENVIRONMENTAL PROTECTION AGENCY
by
GIFFELS ASSOCIATES, INC.
ARCHITECTS-ENGINEERS-PLANNERS
DETROIT, MICHIGAN
JOB NO. 727761001
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TABLE OF CONTENTS
PAGE NO.
I - WHY IS WASTE WATER TREATMENT NEEDED 1
II - PROBABLE WASTE WATER QUANTITIES AND PROPERTIES 4
III - WASTE WATER TREATMENT PROCESSES 7
IV - WASTE WATER SURVEYS 8
V - INITIAL PLANNING FOR A WASTE WATER TREATMENT
SYSTEM 10
VI - SELECTION OF A POULTRY WASTE WATER TREATMENT
PROCESS 11
ACTIVATED SLUDGE PROCESS ^ &• 11
TRICKLING FILTERS Aikerfc 15
LAGOONS Dcx/t 17
COSTS 19
VII - UPGRADING EXISTING LAGOONS 22
VIII - OPERATING A WASTE WATER TREATMENT SYSTEM 26
IX - CASE HISTORY - THE ORIGINAL GOLD KIST WASTE
WATER FACILITIES 33
SITE SELECTION 33
WASTE WATER SURVEY AND CRITERIA 34
SELECTION OF THE TREATMENT PROCESS 37
THE FLOW DIAGRAM 40
DESIGN CRITERIA USED 41
FUTURE EXPANSION PROVISIONS 49
WASTE TREATMENT SYSTEM COSTS 51
OPERATING ARRANGEMENTS 53
PHOTOGRAPHS & DRAWINGS
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11
TABLE OF CONTENTS
PAGE NO.
X - CASE HISTORY - CURRENT EXPANSION AT GOLD KIST 55
PROJECT HISTORY 55
CURRENT WASTE WATER LOADS 55
CURRENT OPERATING DIFFICULTIES 57
PROPOSED WASTE WATER TREATMENT SYSTEM LOADS 62
REVIEW OF COMPONENT ADEQUACY 66
PROPOSED MODIFICATIONS 73
FLOW CHARTS, SKETCHES A THRU D
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TREATMENT FOR DISCHARGE TO A STREAM
I - WHY IS WASTE WATER TREATMENT NEEDED
The discharge of waterborne wastes into a stream may impart
turbidity, reduce dissolved oxygen, form sludge deposits, alter
salinity, alter pH, alter temperature, produce nutrients which re-
sult in undesirable growths and impart toxicity to that stream.
The introduction of any one of these factors in a natural body of
water may adversely affect the flora and reduce the value of that
water to subsequent users. Increased turbidity in a stream may
cause fish kills, effect the growth of green plants by scattering
light and result in settleable solids. Settleable solids may fill
a body of water, cover aquatic vegetation so that it will not grow
and where the settleable solids are organic in nature, may cause
sludge blankets at the stream bottom that degrade anaerobicly (in
the absence of oxygen) with the production of gases tha bouy up
noxious matter causing odors and scum at the water surface. A re-
duction in dissolved oxygen concentration in a stream results from
the introduction of oxygen demanding substances which may be either
organic in nature or inorganic. The organic material reduces dis-
solved oxygen as a consequence of aerobic (in the presence of dis-
solved oxygen) decomposition and inorganic substances may react
chemically with the dissolved oxygen of the stream. A dissolved
oxygen concentration of 5 milligrams per liter (mg/1) is required
for a wholesome life for fish. pH must be maintained in the range
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of 6.5 to 8.5 for a well balanced biological system in the water
course. Acids and alkalis may effect the fishes such that they may
be susceptible to fungus attack. Increasing the salinity of a stream
may result in alteration of the osmotic pressure in fish. Substan-
ces that result in end products which are nutrients, will cause
rapid plant growth. Rapid growth of algae is a common result of
excessive discharge of nutrients such as nitrogen and phosphorous.
Excessive algae growth causes tastes and odors in water supply and
also may result in clogging of water treatment plant intake screens.
Large concentrations of algae may result in extreme variations in
dissolved oxygen concentration from daytime high dissolved oxygen
levels to nighttime low levels. Increased temperature of a water
course results in accelerated oxygen depletion and a disruption of
aquatic life. The discharge of toxic substances to a stream may
destroy aquatic life and render a stream of no value as a water sup-
ply for downstream water users.
Waste water treatment or processing for removal of those ad-
verse constituents described previously is required to protect the
quality of existing water resources. Nearly every lake or stream
in this country today is regulated in terms of the quality and
quantity of effluents that may be discharged into it. Either fede-
ral, state or local agencies have the authority to establish water
quality standards for the effluents and to enforce those standards.
Consequently, one of the best sources of guidance in terms of the
waste water treatment needs of a poultry plant is the authority
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having jurisdiction of discharge into the receiving stream. The
authority having jurisdiction shall determine the quality of the
effluent discharged and can offer guidance, based on experience
with regard to achieving the desired quality of effluent.
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II - PROBABLE WASTE WATER QUANTITIES AND PROPERTIES
The quantity of waste water discharged from process operations
in a poultry plant may range from five to ten gallons per bird with
seven gallons a typical value. Poultry processing waste water is
typically organic in character, higher than domestic sewage in bio-
chemical oxygen demand, high in suspended solids and floating ma-
terial such as scum and grease. Table 1 shows some characteristics
of waste water from a poultry plant.
TABLE 1
ANALYSIS
PH
D.O.
B.O.D.
Suspended Solids
Total Solids
Volatile Solids
Fixed Solids
Settleable Solids
Grease
UNIT
ppm
ppm
ppm
ppm
ppm
ppm
ml/1
ppm
RANGE
6.3-7.4
0-2.0
370-620
120-296
15-20
170-230
AVERAGE
6.9
0.5
473
196
650
486
164
17.5
201
Such waste water from poultry processing plants is typically
organic and responds well to treatment by biological methods.
In biological waste treatment systems, microorganisms utilize
the polluting constituents of the waste water as food to provide
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energy for survival and growth. The primary microorganisms encoun-
tered in waste water treatment are bacteria, fungi, algae, protozoa,
rotifiers and crustaceans. Bacteria can only assimilate soluble
food and may or may not require oxygen depending on whether the
bacteria are aerobic or anaerobic. Fungi must also have soluble
food but are strict aerobes; that is, they must have oxygen to sur-
vive. Algae utilizes primarily inorganic compounds and sunlight
for energy and growth with oxygen given off as a by-product. Pro-
tozoa are single celled animals and utilize bacteria and algea as
their primary source of energy. Rotifiers are multi-cellular ani-
mals which use bacteria and algae as a major source of food. Crus-
taceans are complex multi-celled animals which possess hard shells.
The microscopic forms of crustaceans utilize the higher forms of
microorganisms as a source of food. Protozoa, rotifiers and crus-
taceans grow only in an aerobic environment.
Microorganisms find their place in the carbon cycle existing
at the elemental levels of conversion of residual organic carbon
to carbon dioxide. Briefly, the carbon cycle consists of green
plants utilizing inorganic carbon in the form of carbon dioxide and
converting it to organic carbon using sunlight for energy for photo-
synthesis. Animals consume the resulting plant tissue and convert
part of it to animal tissue and carbon dioxide. Plant and animal
tissue and other residual organic carbon compounds are then oxidized
back to inorganic carbon dioxide by microorganisms.
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Aerobic degradation of waste water constituents is a biochemi-
cal reaction in which living cells assimilate food for energy and
growth in the presence of dissolved oxygen. About one-third of the
organics are oxidized providing the energy to synthesize the remain-
der into additional living cells. The end products of these bio-
chemical reactions are carbon dioxide and water. When oxygen is
absent from the reaction, the degradation is anaerobic and the end
products are organic acids, aldehydes, ketones and alcohols. Special
bacterial called methane formers metabolize about 80 percent of the
organic matter to form methane and carbon dioxide with the remaining
20 percent utilized to form additional living cells. These above
biochemical principles are utilized in waste water treatment sys-
tems to render waste water streams from poultry processing facilities
suitable for discharge to a stream. Waste water treatment systems
in the poultry processing industry usually include primary and sec-
ondary treatment and may or may not include tertiary treatment.
Primary treatment consists of screening, comminutor and primary
sedimentation or floatation for removal of solid and particulate
matter. Primary treatment is discussed in more detail in another
portion of this seminar dealing with pretreatment of poultry pro-
cessing waste water.
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Ill - WASTE WATER TREATMENT PROCESSES
Secondary treatment required for discharge to a stream may be
in the form of an activated sludge system, a trickling filter sys-
tem, a system of lagoons or an irrigation system. Each of these
methods of biological treatment has been tried with varying degrees
of success. Activated sludge systems that may be applied to poultry
plant wastes include conventional activated sludge, activated sludge
using step aeration, high rate activated sludge, extended aeration
activated sludge and the contact stabilization process. Anaerobic
lagoons, aerobic lagoons and a combination of an anaerobic lagoon
followed by an aerobic lagoon may be used for secondary treatment
of poultry wastes. All poultry waste water effluents should be
chlorinated before discharge to the receiving stream.
All of the above processes are described in Part V and represent
the commonly used waste treatment processes. The use of other sys-
tems such as microfiltration, certain chemical processes, etc., while
possible, are generally not used due to high first and operating
costs.
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IV - WASTE WATER SURVEYS
Planning a waste water treatment facility for a poultry plant
begins with a survey of the waste water sources within the plant.
An industrial waste water survey in an existing poultry processing
facility would consist of determining the volume and characteristics
of the composite waste water discharge. The survey may be as sim-
ple as measuring flow and taking a composite sample at a single point
or may be complex as measuring flows and sampling each source of
waste water discharged. The latter has the advantage that each point
within the plant may be studied to determine the possibilities avail-
able for reducing the volume of waste water and pollution at the
source. A discussion of reducing the waste volume within the poul-
try processing plant is given in another portion of this seminar.
For a new poultry processing facility where waste water flow
streams do not exist, the waste water for the proposed plant must
be synthesized based on experience at similar existing processing
plants. Using this method for determining waste water quantity and
character requires great care to insure that all waste constituents
are included in the synthetic waste water sample and that the con-
stituents are included in proportions that will be truly represen-
tative of the waste from the proposed facility. It is suggested
that an experienced engineer be retained to prepare a study which
will determine the properties of the design influent.
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The volume of waste water, in general, will vary with the bird
production; increasing with increased bird production and decreasing
with low production. Sketch B shows how the volume of waste dis-
charged varies with time at one poultry plant. Some of the charac-
teristics of waste water that should be determined include suspended
solids, biochemical oxygen demand (6005), toxic substances, grease
and fats, dissolved solids, solid matter, temperature, pH, color
and septicity.
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V - INITIAL PLANNING FOR A WASTE WATER TREATMENT SYSTEM
Criteria for the design of the treatment plant is available
from the authority having jurisdiction for control of discharge to
the receiving stream and must be evaluated by an engineer experienced
in the design and engineering of waste water treatment plants for
poultry processing facilities.
The selection of type of treatment and type, number and size
of components may be performed when the required treatment efficiency
in terms of removal of contaminants has been established.
Costs, both capital costs and operating costs, must be determined
in the preliminary planning phase of the project. The preliminary
planning phase of the project should result in a report describing
the location of the waste treatment plant, the nature of the wastes,
description of all components of the proposed waste water treatment
system, provisions proposed for future expansion, anticipated removal
efficiency and character of effluent and an estimate of both capital
and operating costs. The preliminary report performs three primary
functions. Firstly, the report may be used in discussions with the
authorities early in the project; secondly, it provides the cost
data essential to an economic feasibility of the project; and thirdly,
it serves as 'a basis for the preparation of working drawings and
construction contract documents.
10
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VI - SELECTION OF A POULTRY WASTE WATER TREATMENT PROCESS
The secondary treatment processes commonly utilized in the
biological treatment of poultry wastes are; 1) various forms of
the activated sludge process, 2) standard and high rate trickling
filters, and 3) aerobic and anaerobic lagoons. In the past, aerobic
and anaerobic lagoons have been employed in the majority of private
installations with activated sludge plants as a second choice. Trick-
ling filters have seen their main usage in joint treatment plants
treating both municipal and poultry wastes. With the exception of
anaerobic lagoons, all of the processes provide complete treatment
and achieve upwards of (70-90%+_) reduction in the influent BOD and
(80-95%+) removal of suspended solids. Each of the systems to be
discussed have their advantages and disadvantages, and in general,
the treatment requirements will dictate, to some degree, the partic-
ular system selected. The main differences between the systems are
construction and land costs. The major costs for activated sludge
and trickling filter plants are construction and operating costs/
whereas, the major expense for lagoons is land utilization costs.
The following discussion will limit itself to the unit operations
and treatment plant equipment associated with each process.
ACTIVATED SLUDGE PROCESS
There are four general types of activated sludge processes;
1) conventional, 2) high rate, 3) extended and 4) contact stabi-
lization. All of the above utilize the activated sludge theory,
11
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previously discussed, whereby, aerobic bacteria assimilate the organic
matter present in the waste stream for cellular growth and in that
way provide for the waste stream purification. The common elements
of all activated sludge processes are; 1) an activated sludge floe,
2) a mixing and aeration chamber, and 3) a clarification or separa-
tion tank.
Conventional Activated Sludge
i
AERATION
6-8 HRS. DET.
WASTE T . RETURN SLUDGE
In the conventional activated sludge process, the waste stream,
following primary treatment, is mixed with a proportional amount of
the returned settled sludge from the final clarifier and enters the
head of the aeration basin. In general, the aeration basin is de-
signed to provide a detention time of six to eight hours. Mixing
and aeration are uniform along the tank and are provided for by
mechanical mixers and/or pressurized air diffusers. Following aera-
tion, the mixed liquor is settled in a clarifier, the clear super-
natant being discharged to the receiving water and the concentrated
sludge being proportionately returned and wasted. One modification
of the conventional process is step aeration, where the waste stream
and/or return sludge enters through a number of inlets along the
aeration basin rather than at a common inlet. A second modification
12
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is tapered aeration, where aeration along the tank is varied. The
advantages of the conventional activated sludge process are; 1)
lower capital costs than equivalent trickling filter plants/ 2) low
hydraulic head losses, and 3) a high quality effluent is attainable.
The disadvantages are; 1) higher mechanical operating costs than
equivalent trickling filter plants, 2) requires skilled operators,
3) does not respond well to shock loads, 4) generates a large volume
of sludge to be disposed of, and 5) problems in sludge settling are
sometimes encountered.
High Rate Activated Sludge
AERATION
2-3 HRS. DET.
WASTE ^ RETURN SLUDGE
The main differences between the high rate process and the
conventional process are the smaller detention period in the aera-
tion basin and a smaller return sludge rate. The advantages of
this system are; 1) lower capital costs than the conventional pro-
cess, 2) the sludge generated is much denser resulting in a less
voluminous sludge to be dispensed with, and 3) because of the shorter
detention time, operating costs are less. The main disadvantage is
the lower quality of the effluent.
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Extended Aeration
AERATION
24-30 HR. DET.
RETURN SLUDGE
In the extended aeration process, the aeration basin provides
for 24 to 30 hours detention time. The advantages of this process
are; 1) the very high quality of effluent, 2) less manpower time
required to operate the process, and 3) smaller volumes of sludge
are generated. The main disadvantages of this process are the high
capital investment required and the possibility of sludge settling
problems.
Contact-Stabilization
WASTE
AERATION
30 MIN. DET.
WASTE
SLUDGE
STABILIZER
AERATION
2 HR. DET.
RETURN SLUDGE
In the contact-stabilization process, the waste stream does
not undergo primary clarification but is mixed with the return
sludge and enters the aeration basin directly. Since the mode of
treatment is by adsorbtion and absorption, a detention period of
14
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only 30 minutes is provided. After settling, the concentrated
sludge is stabilized by separate aeration before being proportion-
ately returned to the waste stream. The main advantages of this
process are; 1) low capital investment, 2) low operating costs,
and 3) ability to handle shock loads and variations in flow. BOD
reductions of 90%+^ and suspended solids removals of 90%+^ have been
reported.
TRICKLING FILTERS
As mentioned previously, the biological mechanism involved in
treating waste water by perculation through trickling filters is by
assimilation of organic matter into cellular growth by aerobic bac-
teria. Unlike the activated sludge process, where the biological
process takes place in a "fluid bed", the biological activity in
a trickling filter is conducted on the filter medium in the form of
a surface fauna. Portions of the bacterial fauna are continually
sloughing off into the waste water stream and are removed in the
final clarifier. Trickling filters can achieve upwards of 90%+^ in
both reduction of BOD and removal of suspended solids. There are
two types of trickling filters; 1) standard rate and 2) high rate.
The number of filters in series determines the "stage" of the fil-
ter system. The primary elements of a trickling filter are the
covered or uncovered containing structure, the filter medium, the
waste flow distribution system, and the subdrain collection system.
15
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Typical mediums utilized are rocks, slag, and recently honey-combed
cellular modules of synthetic construction. Distribution systems
are spray nozzles attached to fixed or rotating manifolds. The
subdrainage system may consist of tile, concrete, or synthetic
drainage tile.
Standard Rate Trickling Filters
WASTE
The main distinction of the standard rate trickling filter is
the low BOD loading rate. Their main advantages are; 1) high
quality effluent, 2) low operating costs, 3) operating personnel
need not be highly skilled, 4) they are resistant to shock loadings
and variations in flow. The main disadvantages are high capital
costs and considerable land space is required. Flies and insects
are sometimes a problem but are usually controllable.
High Rate Trickling Filters
WASTE
TWO-STAGE, HIGH RATE
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The main distinction of the high rate trickling filter is the
high BOD loadings. These loadings may be as much as twice that of
a standard rate filter. Although for a single pass, BOD reductions
are only (60-70%+^, recirculation provides for increasing the total
reduction. The advantages are; 1) versatility of treating high
strength wastes, 2) resistance to shock loads and variations in
flow, 3) highly trained personnel are not required, 4) the area re-
quired is considerably reduced, and 5) problems with flies and in-
sects are usually eliminated. The main disadvantage is the high
power requirements caused by recirculation.
LAGOONS
As was mentioned previously, lagoons are presently the most
common method of treating poultry waste at private waste treatment
installations. This is primarily a result of the availability of
low cost land, when most of the poultry processing facilities were
constructed. Both aerobic and anaerobic lagoons require very large
allocations of land. Successful operation of these lagoons depends
to a high degree on local climatic conditions; generally favoring
warm, clear and sunny conditions. Depending on the geological
site conditions, the lagoon may require lining of the bottom. In
general, the waste stream is pretreated by mechanical screens to
remove offal and feathers. The biological mechanisms responsible
for the purification process have been discussed previously. Me-
chanical aerators and diffused air systems are used in the aerobic
17
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lagoons. A properly designed aerobic lagoon can be expected to
achieve 90%+ reduction in BOD and suspended solids removal. When
anaerobic lagoons are used, expected removals are only (70-80%+_) .
Odor problems are frequently associated with anaerobic lagoons,
although chemical additives can usually control the problem. In
the past, flies, insects and excessive growth of bordering vegeta-
tion have been a problem. The following are some common flow
schematics of lagoon systems.
WASTE
ANAEROBIC
LAGOON
WASTE
AEROBIC
LAGOON
WASTE
fe-
W
ANAEROBIC
LAGOON
fc
W
AEROBIC
LAGOON
WASTE
k.
SEPTIC
TANKS
^
AEROBIC
LAGOON
As an example of the variety of schemes which may be incorpo-
rated into the design of poultry waste treatment systems; one such
plant has combined, as a single treatment system, the extended
aeration and aerobic lagoon concepts to effect a considerable costs
savings plus a reduction in land requirements. This system, which
could appropriately be called an "aerated lagoon" has been on stream
for about six years and reportedly achieves upwards of 90% reduction
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in influent BOD and suspended solids removal of better than 80%.
Since the waste treatment system has been such a success and water
shortage is also a problem at this plant, the EPA has supported
a pilot plant investigation to determine the feasibility of re-
cycling the treatment plant effluent for use as process water.
COSTS
The costs for waste treatment are difficult to project due,
in large part, to their dependency upon local conditions. These
local conditions consist of local design codes, climatic and geolo-
gical consideration, etc. The following table is included to pro-
vide a rough approximation of the costs of waste treatment as applied
to the poultry processing industry. The table was constructed by
adjusting average costs of similar municipal waste treatment fa-
cilities to fit poultry processing requirements. The treatment
costs presented do not reflect land acquisition costs. The values
tabulated are 1967 prices and are based on the present value method
of calculating costs. The selected interest rate is 5% and the
expected life of the structure is 25 years. Considering that the
actual useful life of the facility will be more like 40-50 years
and the fact that the costs are based on equivalent municipal facil-
ities, this approach can be considered conservative and the resultant
values considered "high". Municipal plants often are required to
have parallel facilities and expensive sludge disposal equipment.
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Parallel facilities sometimes increase the costs as much as (100-
300%) and sludge disposal equipment such as sludge digesters, vacuum
filters, and/or sludge incinerators can amount to (30-50%) of the
capital costs. For these reasons, the capital costs shown in the
table can be reduced as much as 50% or more for poultry processing
waste treatment. The table, therefore, only truly indicates rela-
tive costs for the various processes. For example, the "Gold Kist"
waste treatment plant was constructed for a much lower cost than
that shown in the table. This reduction in capital costs were the
result of; 1) climatic conditions did not require a facility to
house air supply equipment, 2) because of available land and the
recycling of by-products, sludge disposal costs were minimized,
3) the retaining lagoon permitted a considerable reduction in clar-
ifier sizing, and 4) parallel facilities were not required.
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POULTRY PROCESSING WASTE TREATMENT COSTS*
TYPE OF TREATMENT
Conventional
Activated Sludge
High-Rate
Activated Sludge
Extended Aeration
Contact
Stabilization
Standard Rate
Trickling Filter
High Rate
Trickling Filter
Aerobic Lagoons
Anaerobic Lagoons
An ae r ob i c/Ae r ob i c
Lagoons
CAPITAL
COSTS
(THOUS.$)
825
660
1,569
473
750
555
740
300
450
LEVEL OF
TREATMENT
(% B.O.D.
REDUCTION)
90+
80+
95+
90+
90+
90+
90+
70-80+
90+
OPERATION &
MAINTENANCE
COST
(C/1000 GAL. )
10.63
6.81
13.61
7.44
6.00
12.27
NEG.
NEG
NEG.
LAND
REQUIREMENTS
(ACRES)
3.0
2.0
3.0
2.5
8.5
5.5
74
15
30
TOTAL
TREATMENT
COSTS
(C/1000 GAL.)
15
11
25
9.4
12
13
8
3.3
4.9
TOTAL
TREATMENT
COST
K/BIRD)
0.15
0.11
0.25
0.094
0.12
0.13
0.08
0.033
0.049
* Based on a flow of 1.0 MGD having a BOD load of 450 ppm. Values given are calculated by the present
worth method based on an interest rate of 5% and an expected facility life of 25 years. Total
treatment costs do not reflect land costs.
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VII - UPGRADING EXISTING LAGOONS
As discussed previously, the problems associated with the ope-
ration of lagoon systems depend heavily on the local climatic con-
ditions. Odors are a common problem; always present in anaerobic
systems and occurring whenever anaerobic conditions develop in aerobic
lagoons. Since there is no control of the biomass, suspended solids
removal and the maintaining of minimum dissolved oxygen levels are
frequently troublesome. A major constituent of the suspended solids
present in lagoon effluents is algae. In the absence of sunlight,
algae require molecular oxygen for endogenous respiration. During
periods which are characterized by low intensity sunlight radiation,
the algae may deplete the dissolved oxygen below the minimum require-
ments resulting in algae degradation and thus the algae exerting a
biochemical oxygen demand. Anticipated stricter effluent criteria,
perhaps on a total pounds or maximum concentration basis rather than
a percentage removal of influent loading, will ultimately force the
abandonment of conventional lagoon systems to other alternatives
or the upgrading of the existing lagoons.
To effect any substantial improvement in the effluent quality,
any steps to upgrade a lagoon system must be oriented towards con-
trol of the biomass. Recent attempts to remove the suspended solids
from lagoon effluents have not met with appreciable success. Be-
cause algae do not form dense floes, clarification, either alone or
22
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combined with chemical flocculation, has not been successful. Chemi-
cal flocculation followed by air flotation has had limited success
but the application of this method to the entire effluent stream
would be economically prohibitive. Conversion of an existing lagoon
system to one of the various forms of activated sludge systems pre-
viously discussed, is both advantageous and economically feasible.
In the activated sludge process, nutrients present in the waste
stream, are utilized in the synthesis of the biomass. Since the
biomass is ultimately separated and removed from the waste stream,
the degree of algae synthesis in the effluent stream is limited.
In order to provide sufficient control of the biomass in con-
verting to an activated sludge system, air supply and solids removal
equipment must be provided. Generally, these will require the in-
stallation of blowers, air distribution systems, floating aerators,
clarifiers, concentrators, strainers, etc. As in all of the bio-
logical systems, some solids will have to be disposed of and con-
siderable attention should be given to reclaiming the solids as
feed meal or fertilizer. Maximum effort should be made to utilize
the existing lagoons as much as possible. In some cases, portions
of the lagoons can be converted to serve as multi-purpose units
such as clarifiers or aerobic digesters, as well as, aeration basins.
Lagoons can also be utilized as "polishing" ponds capable of sup-
porting fish life and providing the capability for recycling the
treated waste water.
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Generally, once poultry processing operations have commenced,
there is more reliable information available such as flows, loadings,
temperatures, waste characteristics, etc., to establish good design
criteria for the upgrading of lagoon systems. Likewise, it is often
found that changes in existing process procedures can result in
reduced flows and loadings, thereby reducing the required sizing of
equipment.
Construction for the upgrading of lagoon systems is best accom-
plished by a "staged" sequence. New construction should be scheduled
when plant production and the waste water flow is at a minimum. In
this way the "staged" concept may allow for plant personnel to per-
form much of the required construction. Likewise, present effluent
criteria can be satisfied while a future water use and waste treat-
ment program is established. "Staged" construction allows for dis-
tributing the capital costs for treatment facilities over a period
of time resulting in minimization of upgrading costs. "Staged" con-
struction could consist of initial installation of improved aeration
systems then later installation of a clarification device followed
by final installation of a system for recirculation of process water
from a polishing pond.
The costs for upgrading existing lagoon systems are often sig-
nificantly less than that which would be required for equivalent
new waste water treatment systems. In short, to minimize both
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present and future treatment costs, the design for upgrading an
existing lagoon system should incorporate, wherever possible, the
existing facilities, process water conservation, and the flexibility
for present or future solids reclamation and treated waste water re-
cycling. Included are some typical flow schematics showing various
methods of upgrading existing lagoons.
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ANAEROBIC
LAGOON
AEROBIC
LAGOON
EXISTING
AIR
RECYCLED,
WATER
4
^
SCREENS
*
«
»
b
FLOTATION
_| 1
1 I
AERATION
BASIN
BAFFLE i
WEIR
>
MS
^
W
\
i
POLISHING
^v.
POND
CHLORINATION-
UPGRADED
-------
-*—
SCREENS
ANAERORIC
LAGOON
EXISTING
RECIRCULATION
SCREENS
WET
WELL
AERATION
BASIN
^ SOLIDS
/\ RECLAMATION
{ ^OR DISPOSAL
CLARIFIER
CHLORINATION
UPGRADED
-------
SCREENS
AEROBIC
LAGOON
EXISTING
SOLIDS RECLAMATION
OR DISPOSAL
RECIRCULATION
CLARIFIER
-*-
SCREENS
AERATION
BASIN
t
POLISHING
POND
CHLORINATION'
UPGRADED
-------
VIII - OPERATING A WASTE WATER TREATMENT SYSTEM
When the waste treatment plant is designed, constructed and
finally placed on stream, it is the responsibility of the waste
treatment plant operator to insure that the equipment performs as
intended. The intent of the waste treatment plant is to reduce
the pollutional potential of the waste water discharge to below
specified limits. The operator must control the flow streams with-
in the plant to achieve optimum efficiency. This may require, as
in the case of activated sludge systems, that the rate at which
sludge is wasted, air applied and the applied chlorine dosage be ad-
justed to assimilate the contaminants emanating from the processing
plant. The pollutional load or contaminants emanating from the plant
depend upon the particular processes used within the plant, the bird
production and the plant personnel. The waste treatment plant op-
erator must learn to anticipate and recognize when the influent has
changed in character and make the necessary adjustments in the waste
treatment plant flow streams before the quality of the effluent has
declined sufficiently to constitute a violation or affect the qual-
ity of the receiving stream. Good indicators from which to judge
the operation of the waste treatment plant are the appearance,
color and smell of.sludge and waste water in the various components
and the general odor at the plant. A successfully operating waste
treatment plant has little or no unpleasant odor.
26
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Maintaining good records of the results of tests and plant
operation cannot be overemphasized. Results of record tests, as
well as operating tests, indicate how well the plant is functioning,
The authority having jurisdiction of the discharge to the receiving
stream is responsible to the public to be aware of how well the
waste treatment plant is functioning. Where good records are main-
tained, the authorities, engineers and others may have ready access
to the history of plant operation which is valuable in providing
assistance in evaluating plant performance and analyzing problems
which may occur.
The successful waste treatment plant is also a well maintained
waste treatment plant. Routine inspection and maintenance pro-
cedures must be developed for each waste treatment plant, however,
a few basic guide lines may be set forth. Each piece of equipment
in the plant should be furnished with a manufacturer's instruction
manual and shop drawings. The operator should be intimately fa-
miliar with these manuals and their contents. These manuals give
complete information on lubrication, adjustments and other equip-
ment maintenance. The waste treatment plant should be visited at
least once each day. Daily, weekly, monthly and yearly check
lists for inspection and maintenance should be developed and fol-
lowed to assure proper waste treatment plant operation and main-
tenance. The following check lists were suggested for an activated
27
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sludge waste treatment plant treating waste water from a poultry
processing plant. These check lists are not intended to be com-
plete but to serve as guidance for an operator to develope his own
check lists.
A. DAILY CHECK LIST
1. Check Air Compressors
a. Check lubrication.
b. Check motor, bearings and compressors for over-
heating.
c. Check air filter for fouling.
d. Change the compressors "in service" (set up a rota-
tion schedule to use all of the compressors, includ-
ing the standby on a daily switch-over schedule so
that all compressors are operated the same amount
of time).
e. Check the "cold" compressor to be put into service
for lubrication, free rotation, clean inlet filter,
etc.
f. Start the "cold" compressor and put it on the line
before shutting down the one(s) in service, start-up
procedure/ lubrication, operation, etc., so you can
satisfy yourself that they are being started and
operated properly and are performing satisfactorily),
g. Allow the "cold" compressor to operate while you are
at the plant and recheck it before leaving.
28
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A. Cont'd.
2. Check Chlorinator
a. For operation, setting.
b. Chlorine supply.
3. Observe air pattern in all tanks. Adjust if necessary.
4. Check final clarifier tank for operation, flow.
5. Check return sludge airlift pump for operation.
6. Check skimmer and scum remover at final clarifier and
by-products collector for operation.
7. Check by-products collector for operation and flow.
8. Check telescoping valve for proper sludge and grease re-
moval .
9. Observe sludge appearance in all tanks. Investigate and
correct any deficiencies.
10. Observe final clarification and by-products collector
tanks. Correct any deficiencies.
11. Observe condition of raw sewage entering the plant.
12. Observe operation of froth spray system (if used). Clean
if necessary.
13. Check operation of comminutor, motor, bearing for over-
heating.
14. Rake screenings from bypass bar screen and remove in
covered receptacle for burial on the site.
15. Skim floating solids from final clarifier and by-products
collector and digester supernatant decant chamber, place
29
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A. Cont'd.
15. Cont'd.
in covered receptacle. Bury. (Suggest a "bug screen" on
long handle such as used for removing bugs, wrappers, etc.
from swimming pools.)
16. Hose down tank and compartment walls, weirs, clarifier
center well, raw sewage inlet boxes,cchannels, etc., to
maintain a clean plant. (Suggest a large hose, 1" to 1-1/2'
with tapered discharge nozzle to "blast" surfaces with
fresh water so that the cleanup will take a minimum of
time.)
17. Correct any plant deficiencies noted.
18. Make tests. (D.O., sludge, chlorine residual, etc.) as
required.
19. Recheck operation of the "cold" compressor.
B. WEEKLY CHECK LIST
1. Use a coarse brush on a handle to brush down accumulation
of algae, etc., that hosing down will not cleanup. Fol-
low by hosing.
2. Check the air compressors and sludge collector mechanism
for oil level and lubrication. (Follow the manufacturer's
instructions, using proper lubrication oils and greases
recommended, observe and schedule oil changes, bearing
lubrication, etc., as recommended by the manufacturer.)
30
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B. Cont'd.
3. Make a test of the sludge solids in the extended aeration
tanks and in the aerobic digester. Correct if necessary
by adjusting the sludge return to the extended aeration
tanks and the aerobic digester.
4. Make a D.O. test of the final effluent. Correct the
amount of air, if necessary.
5. Check the chlorine residual in the plant effluent. Cor-
rect the chlorine feed rate if necessary.
6. Open and close all plant valves momentarily to be sure
they are operating freely.
7. Maintain the premises, rake, mow, etc.
C. MONTHLY CHECK LIST
1. Check and observe the raw sewage flow rate through the
plant.
2. Make a settleable solids (Imhoff cone) test of the raw
sewage entering the plant. Record.
3. Make a settleable solids (Imhoff cone) test of the plant
effluent from the chlorine contact chamber. Record.
4. Collect a sample of the plant influent and a sample of
the plant effluent for a B.O.D. analysis at an indepen-
dent laboratory.
5. Remove, inspect and clean the inlet air filter screens
for the air compressor units.
31
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C. Cont'd.
6. Remove belt guard from sludge collector drive, check
belt tension, grease and service shear pin coupling,
check vent plugs.
7. Remove, clean and check the surge relief valve(s) on
the discharge of each air compressor.
D. YEARLY CHECK LIST
1. Clean, touch up and paint all items requiring attention.
2. Inspect, flush and clean bearings; lubricate and over-
haul all items of equipment.
3. Proceed with any plant modernization or improvement that
need attention.
KEEP AHEAD OF THE WASTE TREATMENT PLANT. ATTEND IT DAILY.
GOOD HOUSEKEEPING AND MAINTENANCE IS A SIGN OF GOOD PLANT
OPERATION. A DIRTY, UNKEPT PLANT IS A POORLY OPERATED ONE.
90% OF PLANT ODORS ARE CAUSED FROM POOR HOUSEKEEPING.
32
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IX - CASE HISTORY -
THE ORIGINAL GOLD KIST WASTE WATER FACILITIES
A - SITE SELECTION
In 1966, Giffels Associates was retained by the Gold Kist
Poultry Processing people, then known as the Cotton Producers As-
sociation, to undertake a study of waste treatment problems in
consideration with a proposed new plant to be built in Suwannee
County, Florida. The location was predicated by the fact that the
cooperative farm r.iembers were experiencing declining returns on
tobacco farming currently being done in the area and the Cotton
Producers Association elected to bring into the area new agricul-
tural business for the benefit of their farmer members.
Poultry was selected as being the most logical since they
wished to expand their poultry processing facilities in any event
and the area was suited to the rearing, hatching and dispatching
of a large quantity of broilers.
The site finally selected was adjacent to the Suwannee River
which offered some degree of diluting water for the treated in-
dustrial waste and also offered a sandy site on which facilities
could be readily built and which was located over a very adequate
ground water supply to furnish the water for poultry processing.
33
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A site of 100 acres was selected for the project giving suf-
ficient room for construction of the poultry processing plant, the
hatchery and the required waste treatment facilities, while pro-
viding a buffer zone between the plant and adjoining property owners,
In addition, the proximity to the interstate highway system offered
a ready means for shipment of dressed poultry and nearby rail ac-
cess at the Town of Live Oak assured adequate facilities for the
receipt of grain and other feed materials.
B - WASTE WATER SURVEY AND CRITERIA
The plant was originally designed to process 50,000 birds per
day on one shift. It's currently being expanded to a two shift
operation with capacity up to 130,000 birds per day which will be
described later.
The original waste water treatment system required facilities
to treat poultry processing wastes from 50,000 birds, processed
over a period of eight hours plus waste waters originating from a
second shift cleanup operation. In addition, all facilities had
to be designed to accommodate future expansion up to or exceeding
twice the then anticipated production rate. In addition to the
normal poultry processing wastes, the sanitary wastes from a plant
population of about 225 persons and waste water from the condensers
on the feed meal cookers had to be included in the total waste
waters to be treated.
34
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An investigation was made at the existing Canton, Georgia
poultry processing operation currently operated at that time by
Gold Kist and the wastes were examined with respect to what loads
could be expected in the new Florida facility. Flow quantities
were measured at Canton and found to be approximately 12 to 13 gal-
lons per bird, however, operations at that time were considered lax
with respect to water conservation and it was decided that the flow
from the new plant would probably be about ten gallons per bird.
Subsequent operations proved this figure to be correct, however,
diligence is always required to maintain water use at that level,
with water consumption practices in the plant being constantly mon-
itored.
An analysis of the waste water being discharged at Canton in-
dicated the following characteristics; pH ranged from 6.3 to 7.4,
dissolved oxygen ranged from 0 to 2 ppm, BOD ranged from 370 to 620
ppm, suspended solids ranged from 120 to 296 ppm, settleable solids
ranged from 15 to 20 ppm, and grease content ranged from 170 to
230 ppm. Average values for these parameters were; pH 6.9, dis-
solved oxygen .5 ppm, BOD 473 ppm, suspended solids 196 ppm and
total solids 650 ppm. Volable solids averaged 486 ppm, fixed solids
164 ppm, settleable solids 17.5 ppm, and grease 201 ppm. Since this
total load was contained in approximately 20% more water then we
assumed would be used at Live Oak, the figures were increased by
1/3 for design purposes because of the expected higher concentra-
tion of contaminants in the waste waters.
35
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In addition to the poultry processing loads, about 200 gallons
per minute of water was to be run through the jet condensers on the
by-product cookers. This water collected the grease and vapors
from the feed meal cooking operations and also had to be treated in
the industrial waste treatment facilities.
When summarized, the daily load on the plant was expected to
be, and later proved to be, about 700,000 gallons per day with a
BOD loading of about 2,620 pounds per day. It should be recognized
that this waste treatment plant therefore was equivalent to a sew-
age plant for a town of approximately 7,000 persons with respect to
its hydraulic flow and to a town of approximately 15,000 to 16,000
persons with respect to its biological load.
Since the waste water flow from the plant personnel was so
small compared to the process waste flow, it was completely ignored
in the original design with the only consideration being given to
that of proper disinfection of the effluent prior to discharge to
the Suwannee River.
Flow variations throughout the day were also measured at Can-
ton with considerable variations being measured but never a no-flow
condition, even during periods of no operations such as weekends.
In other words, with the plant idle/ some flow was experienced due
to water consumption that could not be shut off.
36
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It was determined that the minimum flow rate for the new waste
water stream would be approximately 150 gallons per minute with a
maximum flow rate of about 730 GPM and an average flow rate of about
490 GPM.
An important consideration was the fact that a 20 mesh vibra-
ting screen in the processing plant ahead of the process sewer re-
tained the bird entrails offal, feathers, heads, flushings, etc. so
that those by-products were sent directly to the feed meal recovery
cookers and that the waste water sent to the process sewer did not
contain significant large solids and was relatively free of feathers.
C - SELECTION OF THE TREATMENT PROCESS
Once the waste water treatment criteria had been established,
the decision had to be made as to what type of waste treatment pro-
cess was suitable. The Florida State regulatory agencies said that
lagoons, if built in the area, would have to be fully lined because
of previous problems with ground water contamination in the area.
They would not accept anything except expensively lined lagoons.
Furthermore, the criteria that they set with respect to the discharge
to the Suwannee River was such that a complete lagoon treatment
system would be taxed to achieve the desired results unless the la-
goons were made almost ridiculously large. Consideration was there-
fore given to merely using a lagoon as a tertiary polishing device
and that the front end of the system, the primary and secondary
37
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waste treatment facilities, would have to be biological treatment
facilities capable of achieving pollutant reduction to a point
where the subsequent tertiary pond would be minimum in size and
which would also assure meeting the strict effluent requirements of
the State of Florida. Those requirements at that time were not over
10 ppm BOD and zero settleable or suspended solids with rather strict
requirements with respect to turbidity and color.
It cannot be overemphasized, as can be seen from these very
strict requirements, that in consideration of any industrial waste
treatment process, working closely with state and regulatory agen-
cies is essential before any design work actually begins.
Consideration was given to trickling filters and to various
modifications of the activated sludge process and in the end con-
sidering costs, reliability and other matters, the extended aeration
modification of the activated sludge process was considered the only
possible solution. While this process is often frowned upon in
large municipal work because of its high costs, it must be remem-
bered that in an industrial waste treatment facility, the operating
expenses are written off for tax purposes where capitalization costs
cannot be.
The extended aeration process as it evolved, offered these
advantages: The initial capitalization cost, although high, was not
appreciably higher then other processes considered when sized to
38
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meet the strict effluent criteria. Again, although operating costs
were higher, due to the increased amount of compressed air required
for the process, highly skilled operating techniques are not al-
ways required to keep the system operating near peak efficiency.
In other words, exact lab control is not required.
In addition, the usual 24 hour aeration period required for
extended aeration processes was not conducive to smoothing out the
variations in flow and biological loading that were going to be
experienced in this waste treatment facility. Furthermore, occa-
sional overloads, either hydraulically or biologcally, would not
cause alarming reduction in waste treatment efficiencies. The pro-
cess itself, when properly sized, is almost fool-proof compared to
what happens in a conventional activated sludge system with short
detention periods to trickling filters when overloaded. Certain
waste treatment processes overloaded 10% result in waste treatment
efficiencies dropping off substantially, maybe as much as 50%. A
10% overload on an extended aeration system would cause little
reduction in waste treatment efficiencies.
As a further consideration, the sludge resulting from this
process, being thoroughly degraded, is easy to dispose of on dry-
ing beds, is seldom inclined to cause odor problems and is small in
volume compared to what you might expect from a trickling filter or
activated sludge plant designed and operated by conventional meth-
ods.
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D - THE FLOW DIAGRAM - (PLATE I)
Accordingly, the system was set up somewhat conservatively
consisting of an initial clarifier and skimming device, which was
in reality utilized as a by-products collector mechanism, followed
by aeration tanks with a final clarifier subsequent to all this but
ahead of the tertiary pond. Sludge collected from the final clari-
fier was pumped by an airlift and recirculated to the head of the
extended aeration tank or to the parallel aerobic digester. This
digester is used for long term aeration of grease and excess solids
returned from the final clarifier. It is felt that this aerobic
digester offers the key to successful biological degradation of
any grease remaining from the poultry processing since it aerates
its contents for a period of approximately ten days prior to dis-
charge to the clarifier and thence to the final pond.
Plant sanitary wastes were added downstream from the by-
products collector and were introduced directly into the head end
of the aeration tanks, thereby, eliminating any possibility of
human wastes contaminating feed meal, later fed to the birds.
During subsequent expansion considerations this factor was
felt to be of not significant importance and secondary sludge also
was considered for reclaim.
40
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E - DESIGN CRITERIA USED
The primary settling tank was originally sized by somewhat
conventional means with a surface settling rate of 1,000 gallons
per square foot per day, used as criteria for this work. When we
came to final design we reduced this rate to about 800 gallons per
square foot per day by increasing the by-products collector size
to 40' to permit a little better grease and solids removal.
The criteria for the extended aeration tanks were based on two
factors; 1) we felt it was necessary to maintain the conventionally
accepted basis of 1,000 cubic feet of capacity per 20 Ibs. of ap-
plied BOD per day and also we felt it was necessary to maintain
at least the 24 hour minimum detention period normally used in ex-
tended aeration systems. As it turned out, the 24 hour criteria
governed and, in effect, this turned out to be somewhat longer than
24 hours because the hour flow was considered to be the process
waste flow plus the recirculated sludge, which was returned at 50%
of the total flow rate to the plant. Normally, the 24 hour period
is computed using only the total waste water flow and does not in-
clude the recirculated sludge. We had to begin with, therefore, a
total of 36 hours of detention based on process flow only. This
may be considered almost excessive by some authorities, however,
since we were dealing with the problem of slow biological grease de-
gradation and a need to achieve 98%+ BOD removal and since we were
41
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also looking to expand the plant sometime in the future, it was
felt that this was not an unreasonable criteria to use for the
original plant design. Total aeration tank capacity determined by
this method was1 140,000 cubic feet. It was elected to split this
required capacity into two tanks so that we could operate one and
achieve a responsible degree of treatment while the other was being
maintained or cleaned.
Compressed air was furnished to the tank on the basis of
15,000 cubic feet of air per day, per pound of applied BOD. The
job was not unique in that the equipment selected for air diffusion
consisted of conventional swing-out diffusers used with air headers
in "Y" walls between the tanks. Since the tank was designed based
on hydraulic loading rather than BOD loading; it actually turned
out that we had only 13 Ibs. of BOD applied per 1,000 cubic feet of
tank capacity. Again, quite conservative but as it turned out,
quite successful. As a general philosophy in the design of indus-
trial waste treatment facilities, you must be conservative because
there is no assured means of determining that process loads will
not increase once successful product production lines are put into
operation.
This proved to be the case at Gold Kist.
Subsequent to the extended aeration tanks, a final clarifier
was provided which was also designed on a somewhat conservative
42
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basis, although not to the extend used on the aeration tanks be-
cause we did not have a polishing pond to follow this unit. The
final clarifier was designed on the basis of surface settling rate
of 730 gallons per square foot per day and a weir overflow rate of
360 gallons per foot per day. Sludge collected by the final clari-
fier, which was equipped with a skimming arm as well as scraping
mechanism, was returned by an airlift to the head of the system.
This minimized maintenance and operation problems because at
this point the only motors needed for the system were those on the
blowers and the drive mechanisms for the by-products collector and
final clarifiers. Additional sludge pumps were not required.
Again, when we got down to final design this tank diameter was
increased slightly so this criteria was even less. We were con-
stantly looking to achieve a system that could be somewhat over-
loaded without causing a significant reduction in waste treatment
efficiency.
It was strongly suspected that it might be possible to process
up to 10,000 birds per hour on occasion which indicated that a one
shift operation could run as high as 70,000 to 80,000 birds per
shift if the processing plant were run at a maximum rate. This
actually did happen with production rates approaching 10,000 birds
per hour and the single shift operation extending to nine or ten
hours per day.
43
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The aerobic digester, which was provided adjacent to the
aeration tank, had a volume of 46,500 cubic feet. Air was supplied
in exactly the same fashion as to the aeration tanks on the basis
of 20 cubic feet per minute of air per 1,000 ft. of digester capa-
city. A supernatant decant well was provided at the end of the
digester with clarified liquor rising slowly and very quiescently
since the overflow rate can be controlled by the operator based on
the amount of sludge he returns to the aerobic digester, with the
remaining amount of return sludge sent to the aeration tanks.
This supernatant decant well was actually nothing but a timber
baffle with a hopper bottom built into the end of the aerobic
digester.
Sludge from the aerobic digester was directed to the sludge
drying beds by the simple means of a fire hose utilizing the head
on the aerobic digester to force the sludge to the drying beds.
As a general rule of thumb, the amount of solids generated by the
extended aeration system consists of about 1/2 Ib. per solids per
day per pound of BOD treated in the tanks.
The sludge drying beds were perhaps the weak spot in the
system. Although north Florida seems to be entirely made up of
deep sand beds, we somehow, unwittingly, picked the only spot of
clay in Suwannee County into which to build the drying beds. There-
fore, although subdrainage systems were provided to dry the sludge,
44
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it did not dry as readily as hoped for. Further complications were
involved in the fact that at least initially the outlet from the
underdrains in the sludge drying beds was completely filled over
by some incidental grading operations done by a contractor.
The old rule that if anything can go wrong on a project it
will, seemed to apply here.
Even though difficulties were experienced with the sludge
drying beds, it was not serious because the nature of the sludge
produced by this waste treatment process is such that it is inof-
fensive, dries readily, and in a pinch can just be spread out on
the ground. It will not prove to be troublesome with respect to
odors and can always be scraped up and hauled away from almost
any place you care to temporarily store it, as long as it can be
allowed to dry. Warm Florida weather helped us in this matter.
Sealing of the final tertiary pond subsequent to the clarifier
was accomplished, rather inexpensively. Asphalt liners, rubber
linings and other membranes were considered and the cost always
proved to be somewhat shocking so we ended up with a rather simple
system. A thin layer of visqueen was placed over the entire bottom
of the lagoon in small overlapping sections and trucks full of sand
dumped directly on the visqueen. The sand was spread by hand,
making a one foot layer of earth and sand on top of the visqueen
45
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to protect it. The system may not have been 100% watertight but
we were pleased to note that before any water was added by the
waste treatment process to the lagoon, it did collect and store
rain water and was ready to go at the time the poultry processing
facility went on-stream.
The inlet to the square four acre pond was located in its
geometric center. This was done so that any inadvertant solids
carry-over from the final clarifier would settle out in the central
area of the pond and if there were an odor problem resulting from
this, it would be at least 200 ft. from any point on the shore.
The best way to control an odor is to keep it as far away
from people's noses as you can.
Effluent from the pond was subjected to 20 minutes detention
in a chlorination pond. A chlorinator was provided capable of
application of from 20 to 100 Ibs. per day of gaseous chlorine.
The expected required rate was approximately 42 Ibs. per day to
leave a 0.5 ppm residual in the effluent.
New developments in chlorination of effluent by means of elec-
trolytic cells generating sodium hyprochloride have come into use
since this time and in retrospect I think such a system would be
wise to install in a facility such as this to eliminate the hazards
of using gaseous chlorine.
46
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The air compressor facility for the initial waste treatment
plant consisted of three, 3,000 cu. ft. per minute per Spencer
turbo compressors, each with a 75 HP motor delivering air against
96 oz. of pressure. Actually, two compressors were required to
run full time to furnish air to the aeration tanks and airlift.
the third compressor was merely a standby.
In summary, the waste water treatment plant components con-
sisted of the following devices, which are detailed on the included
drawings.
1. A by-product collector tank, a conventional circular settling
tank with motor driven sludge collection and skimming mecha-
nisms, 40 ft. in diameter with a seven foot side water depth
and a detention time of approximately one and one-half.
2. Extended aeration tanks consisting of two concrete tanks each
170 ft. long, 26 ft. wide with a water depth of 15 ft. and a
free board of two feet. Each tank contained 95 air diffusers
and piping to supply 150 cu. ft. per minute of air to the
mixed liquor. A valve port between the two tanks permitted
equalizing loading on each tank if required. The detention
time was 24 hours based on process flow plus 50% allowance
for sludge recirculation.
47
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3. The aerobic digester was constructed next to the aeration
tanks, therefore, it had an equal length of 170 ft. but it was
only 21 ft. wide, again with a water depth of 15 ft. The su-
pernatant decant well at the end of the tank which was used
to contain the solids in the tank had a surface settling rate
of less than 800 gallons per sq. ft. per day and an overflow
rate of 240 gallons per minute to the clarifier.
4. The final settling tank was again a conventional collection
mechanism with a motor driven scraper and skimming mechanism.
It was made 44 ft. in diameter with an eight foot side water
depth and a nine foot center depth. Detention time in this
tank was about two hours, which is the maximum you could pro-
bably use without running into septicity problems in the
stored sludge.
5. The final stabilization pond or tertiary device was four acres
in size and had a detention time of approximately ten days.
The depth was five feet, which is about the maximum that can
be used in an aerobic pond, simply because depths in excess
of five feet tend to become septic at the bottom due to lack
of sunlight and poor oxygen transfer.
6. The chlorination facility was simply a small building with a
wall mounted chlorinator, scales and ancillary devices and
48
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6. Cont'd.
was placed at the far end of the ponds, convenient to the
chlorine detention pond.
7. The air facility, consisting of the three Spencer turbo com-
pressors for this use rather than positive displacement rotary
compressors for the simple reason that we believed they were
less expensive and more reliable, and certainly less noisy.
Judgement has proved us out on this fact and we have made the
use of turbo compressors as opposed to positive displacement
air compressor devices standard waste treatment works wherever
possible. Their one drawback is that the pressure they can
develop is somewhat limited and you cannot discharge into
really deep aeration tanks. About the best you can do is
operate with about 13 ft. of water pressure and the aeration
diffuser devices.
F - FUTURE EXPANSION PROVISIONS
The entire facility was arranged to permit future expansion if
necessary, and piping was valved and placed so that we could add
another by-product collection tank if we had to. We could also add
another final settling tank if required and we could also add more
air compressors, which were done on the expansion which took place
in 1970.
49
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In addition, there was space on-site to double the stabiliza-
tion pond and add additional chlorination detention ponds if neces-
sary. It cannot be overemphasized that you have to have a site
that is big enough for your waste treatment facilities and 100%
expansion if necessary. We were able to accomplish 100% expansion
without doubling up on these facilities as we'll discuss later.
However, at the time it seemed to be the practical way to handle
the problem.
No expansion provisions were provided in the original aeration
tank installation since we, in effect, had over-designed and felt
that in a pinch we could go to a conventional activated sludge
operation which would require less tank volume but more sophisticated
control. In such a case, only six or eight hours aeration time
would be necessary.
The facility was originally designed to achieve BOD reduction
in the following fashion. Of the 2,600 Ibs. of BOD applied per day,
780 Ibs. would be removed in the by-products collector, 30% of the
applied load. This is a conventional criteria for devices of this
type. It was expected that the subsequent extended aeration tanks
would be able to remove 90% of the remaining 1,820 Ibs. applied
BOD. Again, this seems to have been not an unreasonable assumption
since 90% removal using long term aeration is quite feasible.
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The stabilization pond also was capable of removing another
200 Ibs. of BOD per day, which at the rate of 50 Ibs. per acre
per day which rate is allowed in the State of Florida. As you go
further north you find that colder temperatures inhibit biological
actions in lagoons and that in the northern states, 20 to 30 Ibs.
of BOD loading per acre per day is all that is allowed.
We have had instances on other Florida jobs where it has been
proven that we have removed as much as 100 Ibs. of BOD per acre per
day which indicates the State criteria is probably somewhat conser-
vative.
Totaling up the removal of BOD in all components we were able
to indicate, in theory at least, we were going to remove 100% of
BOD. Although we all knew that this was impossible, we did expect
97 to 97% BOD removal which is very good efficiency. After the
plant went into operation we achieved these results and perhaps
even a little better which justified our selection of the process
and our conservative design approach.
G - WASTE TREATMENT SYSTEM COSTS
The total cost of the waste water treatment facility built in
1967 was estimated to be $252,000.00. We suspect it may have cost
somewhat more, however, since the construction costs for the waste
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treatment facilities were lumped in with the construction cost for
the on-site hatchery and poultry processing plant, the exact cost
could not be determined. In any event, the cost was less than
$300,000.00.
Amortizing the costs over a ten year life expectancy of the
facilities, we found that the original investment of $252,000.00
plus an allowance for interest on that investment, made a total
cost of the facility $327,000.00. Based on processing 250,000
birds per week at a dressed out weight of 2-1/2 Ibs. per bird, it
turned out that the capitalization cost for waste treatment for
this plant was approximately 1/10 of a cent per pound of finished
dressed poultry.
Operating costs were estimated to be approximately seven man-
hours per week of labor, seven days of power for the two blowers
running continuously and seven days worth of chlorine which was
estimated to cost about $6.00 per day. Total weekly operating
costs came out to be about $370.00 which indicated an operating
cost of about .06$ per pound of finished product. Therefore, the
total waste treatment costs per pound of dressed poultry appeared
to be in the neighborhood of 162 mils per pound of finished dressed
poultry.
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H - OPERATING ARRANGEMENTS
In addition to an adequate design of waste water treatment fa-
cilities, another important matter must be mentioned. The true
success for any waste treatment operation is based as much on op-
erating skill as on the design and capacity of the system. As
engineers responsible for the design of this system, we were most
fortunate to have an owner who elected to go out and hire a skilled,
competent man to run these facilities. He was also assigned the
job of running the by-product reclaim system and cookers, therefore,
he was assigned a job in which if he reclaimed his by-products
effectively, his waste water loads were less and he was, therefore,
in complete control of his own destiny. If he messed up on one
job, he would not be able to straighten it out on the other.
A licensed certified waste water treatment plant operator in
the State of Florida, Mr. Ronald Lanier, was hired to operate these
facilities and their success is due to, in a great part, to his
careful attention to facilities operations.
To help him in his job, an operating manual was prepared which
described the plant, its flow stream and theory, its initial start-
up procedures, its normal operating procedures, a check list for
maintenance and a check list for equipment operation was also in-
cluded. The importance of an operating manual prepared by the
design engineer cannot be minimized.
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Before describing the waste treatment plant modifications
now being made to accommodate increased poultry processing, a few
photographs have been included to illustrate the components in
detail.
54
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COTTON PRODUCERS ASSOCIATION
Gold Kist Division
Live Oak, Florida
POULTRY CENTER
ILLUSTRATION
• ' R>
ENTRAILi,, OFFAL, HEADS, AND OTHER WASTE MATERIAL
?
POULTRY PROCESSING
PLANT
-------
COTTON PRODUCERS ASSOCIATION
Gold Kist Division
Live Oak, Florida
POULTRY CENTER
Process Waste Entering Sump
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COTTON PRODUCERS ASSOCIATION
Gold Kist Division
Live Oak, Florida
POULTRY CENTER
Feed Meal Recovery From Primary Sludge
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COTTON PRODUCERS ASSOCIATION
Gold Kist Division
Live Oak, Florida
POULTRY CENTER
Air Compressors Serving Return Air Lifts, Aeration Tanks and Aerobic Digester
-------
COTTON PRODUCERS ASSOCIATION
Gold Kist Division
Live Oak, Florida
POULTRY CENTER
Aeration Tanks
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COTTON PRODUCERS ASSOCIATION
Gold Kist Division
Live Oak, Florida
POULTRY CENTER
Air Header Lifting Mechanism -Aeration Tanks
-------
COTTON PRODUCERS ASSOCIATION
Gold Kist Division
Live Oak7 Florida
POULTRY CENTER
By Products Collector - Primary Clarifier
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COTTON PRODUCERS ASSOCIATION
Gold Kist Division
Live Oak, Florida
POULTRY CENTER
Final Effluent From Pond
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COTTON PRODUCERS ASSOCIATION
Gold Kist Division
Live Oak7 Florida
POULTRY CENTER
Final Clarifier
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COTTON PRODUCERS ASSOCIATION
Gold Kist Division
Live Oak, Florida
POULTRY CENTER
A Typical Large Trickling Filter
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COTTON PRODUCERS ASSOCIATION
Gold Kist Division
Live Oak, Florida
POULTRY CENTER
Final Lagoon - Tertiary Pond
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X - CASE HISTORY - CURRENT EXPANSION AT GOLD KIST
A - PROJECT HISTORY
The original facility was designed to treat waste waters re-
sulting from the processing of 50,000 birds per day plus a nearly
insignificant sanitary waste water flow from the plant personnel
facilities. The rationale by which hydraulic, biological and
solids loadings were determined has been described previously.
Also described therein are the basic criteria used for deter-
mining facility component sizes and the provisions for future ex-
pansion as foreseen at that time. During final design, however,
the sedimentation facilities were increased in size.
This somewhat arbitrary increase in the size of the by-products
collector tank (primary settling) to 40 ft. diameter and the final
clarifier (secondary settling) to 44 ft. diameter is the principal
reason, along with a conservative original design, why the system
has continued to function well under recent substantial overloads.
For these same reasons, the modifications now required are minimal
in extent.
B - CURRENT WASTE WATER LOADS
Once poultry processing start-up difficulties have been over-
come, it was economically practical to increase hourly production
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rates and the one shift processing time to nine or ten hours. This
resulted in daily processing rates of 72,000-80,000 birds per day
and measured hydraulic loads of about 1 MGD. This roughly 50% in-
crease in production caused flow rates ranging from 1.7 MGD to 0.4
MGD on processing days and during weekends (supposedly no flow
conditions) 0.2 MGD flows were recorded. This information is in-
cluded with the Sketch B flow chart.
Original flows were expected to be ten gallons per bird (pro-
cessing and cleanup) plus four gallons per bird for by-products
cooker condenser cooling waters for a total flow of 700,000 GPD.
Actual measured waste water flows have averaged 13 gallons
per bird and totaled over one million gallons per day.
In addition, laboratory tests showed the properties of the
waste waters to be above average during processing hours as
follows:
ORIGINAL ASSUMPTIONS MEASURED PROPERTIES
Total Solids 650 ppm 910 ppm
Suspended Solids 200 ppm 300 ppm
BOD 470 ppm 420 ppm
NOTE: A large part of the increase in solids is due to the fact
that the by-products collector sludge has often contained
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too much water for consistently economical reclaim. When
pumped back over the by-products reclaim screens in the
processing plant, many fine solids pass through back into
the process waste sewer.
C - CURRENT OPERATING DIFFICULTIES
As the loading on the waste water treatment passed the design
criteria, problems arose in the operation of the facility. These
problems were met as they arose by Mr. Ronald Lanier, the certi-
fied waste water plant operator hired by the owner. By skillful
operation of the facility, consistent results were obtained. The
proposed revisions include measures to correct system deficiencies
now apparent and include a new package laboratory permitting the
operator to exercise better control.
CONDENSER COOLING WATER
While an allowance of 0.2 MGO was made in the original design
for use of process water to condense feed meal cooker vapors, even
more water has been required. Problems were encountered from the
very beginning with feathers in the process waste stream clogging
the condenser cooling water pumps. Although it was originally
intended that the recirculation well be located downstream of the
secondary sedimentation device (clarifier) as shown on Illustration
57
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C (Flow Diagram) bound herewith during final design it was installed
between the roughing screens and the by-products recovery tank
(primary settling). This decision was based on terrain and plant
configuration and in hind sight was unwise.
Although ample process waste water was available during pro-
cessing hours to meet the anticipated 140 GPM demand of the feed
meal cooker condensers, the demand proved even higher and the
ing difficulties precluded the use of any process waste water. In
addition, the low process waste discharge flows during cleanup and
no processing hours caused the waste water stream to heat up to an
unacceptable temperature (120° F.+) even when condenser cooker
water pumps were operable. At these temperatures, successful con-
densing of the odorous cooker vapors was incomplete.
As a result, it was necessary to connect an additional un-
metered process water line into the cooker vapor condensers with
a nearly 24 hour constant water flow and resulting discharge to
the process sewer. This flow is believed to be almost entirely
responsible for the increases in flow above the metered process
water consumptions of ten gallons per bird. In other words, about
0.30 MGD (3-1/2 gallons per bird) of process waste water flow
above that expected (ten gallons/bird) has been due to this pro-
cessing complication. When added to the average daily metered
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process water consumptions of 740,000 GPD (processing and cleanup
for approximately 75,000 birds per day), the approximate 1 MGD
flow which was measured was confirmed.
During late May, 1970, condenser water pumps, however, were
successfully relocated from their original location to the process
waste sump in the waste treatment facility. Several days of clog-
free operation were then possible. During these periods, metered
process water demands dropped by 0.1 MGD to 640,000 GPD or only
8-1/2 gallons per bird (average).
Such examples prove that a ten gallon per bird process waste
water estimate is ample providing all by-product cooker condenser
cooling water can be taken from the process waste water stream.
The successful operation of the waste water treatment facilities
under the proposed two shift, 115,000 bird load is predicated on
this assumption and will be discussed further herein.
HYDRAULIC OVERFLOWS
At times of peak processing, slight overflows have spilled
onto the ground from the aeration tank effluent troughs and aera-
tion tank weirs have flooded out (See Sheet CE-14).
The original anticipated design flow rate between the aeration
tanks and final clarifier was 0.7 MGD (490 GPM) + 50% (peak flow
allowance) +0.50 MGD (350 GPM) sludge recirculation or approximately
1.55 MGD (980 GPM).
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A system head curve for the gravity flow line (C = 100) be-
tween the aeration tanks and the final clarifier (See Sheet CE-16)
revealed only 1.2 ft. elevation differential required. Effluent
trough overflow was considered at that time (original design) to
be unlikely.
However, recent peak flow rates of nearly 1.7 MGD plus sludge
recirculation have caused a flow rate of over 2 MGD in the aeration
tank discharge line. At this flow, about 2.5 ft. of elevation
differential is required. Since the design provided for 3.5 ft. of
elevation between the aeration tank water surface and the final
clarifier water surface, these recent overflows were still unex-
plained.
Recent checking of "as built" elevations, however, reveal only
a 2.5 ft. +_ difference in elevation; apparently a construction er-
ror was made. Later discussion contained herein will describe
corrective work required.
SOLIDS CONTROL
The plant operator has been plagued by problems relating to
solids control. Not only has he had difficulty maintaining op-
timum MLSS ratios, but also with removal of sludge from the aerobic
digester to the sludge drying beds. These problems have generally
been caused by the following complications.
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1. Uncanny intuition on the part of the designers placed the
sludge drying beds in the only pocket of clay in an otherwise
all sand site.
2. Earth spoil from construction done subsequent to start-up
was placed in the only available low spot on the site. Un-
fortunately, this also buried the outlet end of the sludge
bed subdrainage system.
3. The sludge drawoff pipe from the aerobic digester was in error,
placed on the wrong side of the decant baffle (See Section
R-R, Sheet CE-18). Instead of being able to draw a concen-
trated liquor from the quiescent side of the baffle in a steady
stream, it was required to shut off the digester air supply
and draw only whatever sludge settled in the vicinity of the
outlet pipe. Time for this was limited due to rapid decrease
in the digester content dissolved oxygen residuals.
Proposals for correction of these deficiencies follow herein.
ODOR PROBLEMS
During weekend periods of low or near zero flows, oxygen levels
in the by-products collector (primary settling tank, Sheet CE-13)
and lift station sumps often disappear and septicity with resulting
odors occurs. Proposed revisions described later have corrected
these conditions.
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In addition, frequent power outages (three to four times a
year) have presented problems with the air compressors which re-
quire a manual restart sequence. Aeration tank contents have be-
come offensive by Monday A.M. when such outages occur on Friday
night or Saturday. System improvements have provided for automatic
air compressor restart.
D - PROPOSED WASTE WATER TREATMENT SYSTEM LOADS
HYDRAULIC LOADS
Actual process water flows recently measured during processing
periods have ranged from 51,000-40,000 gallons per hour. Therefore,
during these times we have had an average flow rate (metered process
water) of about 45,500 GPH or a 1.1 MGD rate. Average bird pro-
cessing rate during these times has been 9,400 birds per hour, so
that processing time seems to require about an average of five gal-
lons per bird.
Assuming the actual use to be six gallons per bird for the sake
of conservative design, and based on occassionally reached proces-
sing rates of 10,000 birds/hr., the maximum process waste water
flow rates expected may reach 10,000 birds x six gallons/bird T
60 = 1,000 GPM or about a 1.4 MGD rate.
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Recently measured cleanup water consumptions have ranged from
239,000 GPD to 294 GPD or an average of 266,000 GPD. The average
daily number of birds processed during this time has been 76,000
birds per day with a range of from 72,000 to 80,000 birds per day.
This indicates cleanup water demands of about 3.5 gallons per bird.
This flow generally occurs in the six hours following the end of
the poultry processing work, the initial flow roughly equaling the
process flow, and gradually decreasing thereafter to supposedly
near zero flow about six hours later, hence the average flow during
the six hours cleanup period is about 500 GPM or about a 0.7 MGD
rate.
Data gathered indicates minimum weekend flows of about a 0.2
MGD (140 GPM) rate. This is presumed to be a completely shutdown
flow rate and is due to sanitary flows, infiltrations and other
miscellaneous water consumption that cannot be reduced further.
This data plus the unmetered cooker condenser flow estimate has
been used to produce the hourly flow rates shown in Sketch B.
Sketches C and D curves indicate expected average and maximum daily
flows expected from the increased poultry processing. These fu-
ture hourly flow rates and total daily flows are based on the
following premises.
1. The processing of 115,000 birds per day in 16 hours will re-
sult in an average production rate of 7,200 birds per hour.
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1. Cont'd.
This is a somewhat lower rate than at present when an average
of 75,000 birds are processed in eight hours (9,400 birds per
hour).
2. Peak hourly processing rates of 10,000 birds per hour will
again be possible and will occur on days when production
reaches the proposed maximum of 130,000 birds per day; peak
flow rates of 1,000 GPM of process waste water will be genera-
ted at such times.
3. Process water demands will not exceed six gallons per bird
and cleanup demands will not exceed four gallons per bird.
This seems readily obtained based on present operating expe-
rience.
4. Waste water flows will be minimized by discontinuing the use
of unmetered process water for by-product cooker vapor con-
densing. All condenser water demands will be met by using
untreated process waste supplemented when required by recir-
culation of by-products collector tank (primary settling)
contents and aeration tank contents. At these times, those
waste treatment system components will be, in effect, heat
exchanger devices. Anticipated maximum water temperatures
in those components will not exceed 120° F. and should not
therefore be detrimental to biological processes.
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It was demonstrated by Sketches B, C and D that although total
waste water flows will increase by 5-12%, peak flow rates will ac-
tually be reduced by 16%.
BIOLOGICAL LOADS
The original design anticipated a BOD load of 2/600 Ibs. per
day while processing 50,000 birds per day or 0.052 Ibs. of BOD per
bird.
If cooker condenser water recirculation were continuously
practiced instead of using fresh unmetered, this BOD load should
have been contained in 50,000 gallons (4,170,000 Ibs.) of water
per day which would then have had an average BOD concentration of
624 ppm. With additional water for cooker vapor condensation, the
flow was estimated to be 700,000 gallons per day. At this time,
the average BOD concentration in the raw waste would have been
446 ppm.
Laboratory tests made on waste water flows found an average
influent BOD of 350 ppm and 397 ppm. These tests indicate that
the originally anticipated BOD assumptions were quite adequate.
Influent grab samples during processing hours (4-22-69) found
a peak influent BOD of 550 ppm. This increased to 650 ppm during
those hours when wastage of by-product collector sludge through
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by-product area screens was practiced instead of being sent to the
cookers for reclaim. These figures are similar to those BOD con-
centrations assumed during the original design work.
The monthly operating reports for the year 1966 indicate
gradually increasing loads on the waste treatment facilities as
production increased. Near the end of 1969, it became necessary to
run the third standby blower continuously to satisfy oxygen demands.
E - REVIEW OF COMPONENT ADEQUACY
LIFT STATION (Sheet CE-17)
The existing lift station contains three separate sumps, e.g.
process water, sanitary sewage and by-products. Although total
flows are expected to increase slightly, maximum flow rates should
decrease so that no changes are required in this facility. How-
ever, to insure an ample cooker vapor condenser cooling water supply,
a new 1,000 GPM non-clog pump will be installed where space was re-
served for the future third process waste pump. The discharge for
this pump will run by means of a new six inch force main back to
the by-products area.
BY-PRODUCTS COLLECTOR (Sheet CE-13)
Under present conditions this 40 ft. diameter tank has an av-
erage surface settling rate of 765 gallons per square foot per day
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and an average weir loading rate of 7,650 gallons per foot per day.
Short term peak flow rates have probably reached twice these values.
With the increased production on a two shift basis, the aver-
age surface settling rate is expected to increase to 805 gallons
per square foot per day and the average weir loading rate to 8,050
gallons per foot per day. Since peak flow rates will be reduced
by about 200 GPM and since this facility has averaged a 39% reduc-
tion in BOD, it is believed the increased loads can be handled
without modifications. The BOD removal rate is undoubtedly en-
hanced by the substantial grease removal in this tank.
AERATION TANKS (Sheet CE-14 and Sheet CE-15)
The extended aeration process utilized in these tanks has been
very successful in meeting the present system overloads. With an
assumed average BOD influent concentration of 450 ppm, 35% reduction
of BOD in the by-products collector and a 0.93 MGD flow, the pre-
sent loading on the aeration tank is probably 2,260 Ibs. of BOD per
day more or less. The present detention time in the aeration tank
is (2 x 525,000 gallons T 930,000 GPD = 1.13 days) 27 hours. With
the standby blower presently on at all times, the air supply to
the tanks has been increased by about 50% over the original design
and is now about 1,425 cfm to each tank or 2,850 cfm total.
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Based on these figures, current aeration tank operating data
is as follows.
Applied BOD/day 2,260 Ibs.
Daily Flow 0.93 MGD
Detention Time 27 hours
Tank Volume per pound of
Applied BOD/Day 62 cu. ft. or 16.2 Ibs. of BOD
Air Supply per Pound of
Applied BOD/Day 1,830 cu. ft.
Air Supply per 1,000 cu.
ft. Tank Capacity 20 cfm
Proposed modifications to the aeration tanks will consist of
approximately doubling the number of Walker Process Sparjers on
each header and increasing the air supply to 1,900 cfm of air to
each aeration tank.
With 100% condenser cooling using process waste and at peak
processing rates (130,000 birds per day) and once again assuming
.052 Ibs. of BOD per bird, the following aeration tank data is de-
veloped. This is again predicated on 35% BOD removal in the by-
products collector.
Applied BOD/Day 4,400 Ibs.
Daily Flow 1.04 MGD
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Detention Time 24 hours
Tank Volume per Pound of
Applied BOD/Day 32.0 cu. ft. or 31.5 Ibs. of BOD
per 1,000 cu. ft. of tank capacity
Air Supply per Pound of
Applied BOD/Day 1,250 cu. ft.
Air Supply per 1,000 cu.
ft. of Tank Capacity 27 cfm
If this were a conventional activated sludge application, cer-
tain of the preceeding data would tend to indicate that the aeration
system had been pushed to a practical limit, however, the long de-
tention time and ample air supply should assure continued operation
as an extended aeration system. Under these conditions, however,
the settling properties of the sludge in the final clarifier should
be improved (less light, endogenous cellular material), however,
waste sludge volumes may increase by several times over what has
been encountered up to this time. Improved sludge wastage facili-
ties are described later herein.
FINAL CLARIFIER (Sheet CE-16)
The performance of this unit will probably actually improve
under the additional loading. Settling properties of the sludge
contained in the mixed liquor received from the aeration tanks
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should be improved and the twenty-four (24) hour aeration period
almost precludes sludge bulking under normal operation. This 44
ft. diameter unit is currently operating with an average surface
settling rate of 612 gallons per square foot per day and a weir
loading rate of 680 gallons per foot per day. These will increase
to 645 and 710 respectively, but again as in the case of the by-
products collector, peak flow rates will be less.
The return sludge airlift which forms a part of this component
was originally designed to return 350 GPM + of sludge to the head
end of the aeration tanks and/or aerobic digester. This amounted
to 70% of the anticipated average hydraulic load (700,000 GPD =
490 GPM). Under present conditions (0.93 MGD), it is returning
sludge at a rate of 50% + of the total flow through the facility.
Since the new average hydraulic load is only slightly greater, the
airlift should still be adequate.
AEROBIC DIGESTER (Sheet CE-14 and CE-18)
The aerobic digester as originally designed was sized on the
basis of 4.5 cu. ft. per capita based on an average of the hydrau-
lic and biological population equivalents; research of the litera-
ture at that time did not disclose much precedent for sludge designs.
The resulting capacity of 46,500 cu. ft. was supplied with 20 cfm
of air per 1,000 ft. of capacity to assure adequate mixing and
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dissolved oxygen residuals. The decant well surface area (256 sq.
ft.) was considered capable of retaining all solids in the system
if sludge were wasted to the digester at a rate not in excess of
10,000 GPD (375 gallons per sq. ft. per day). Actually, required
sludge wastage flow rates were considered as probably being con-
siderably less.
Further, recent research on this matter had disclosed that the
extended aeration system generates about 0.5 pounds of solids for
every pound of applied BOD. This data is developed and set forth
in the paper "Design Criteria for Extended Aeration" by John T.
Pfeffer, Asst. Prof, of Civil Engineering, University of Kansas
and published in the transactions of the 13th Annual Conference on
Sanitary Engineering at that university.
With the future applied load of 4,400 Ibs. of BOD per day on
the aeration facilities, about 2,200 Ibs. per day of solids may
be generated. If these were contained in a sludge having a water
content of 99.8%, about 1,100,000 Ibs. or 132,000 gallons per day
would have to be wasted to the aerobic digester. Under these flow
conditions (92 GPM), the surface settling rate on the decant well
of the aerobic digester would be only 515 gallons per square foot
per day, the weir loading rate would be 8,200 gallons per foot per
day and the digester detention time would be approximately three
days. With a regular daily sludge drawoff, the aerobic digester is
still believed quite adequate.
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SLUDGE DRYING BEDS (Sheet CE-7)
The original sludge drying beds provided had a total area of
approximately 20,000 square feet. On the basis of the original
biological population equivalent, this amounted to 1.33 square feet
per capita.
Although the plant has been operating under a 50% +_ overload
condition, the area has still proved ample, however, the method by
which digester sludge is conveyed to the beds has been less than
satisfactory.
The fact that the sludge is the end product of an extended
aeration process and has been further subjected to several days of
additional aerobic digestion has resulted in small quantities of
a readily dried product with no offensive odors.
One additional 10,000 sq. ft. drying bed with underdrains will
be constructed and the existing beds and underdrainage system im-
proved to provide more capacity and eliminate previously discussed
operating problems.
STABILIZATION POND (Sheet CE-1 and Sheet CE-6)
The stabilization or polishing pond has an area of 193,000 sq.
ft. or 4.4 acres. A high dissolved oxygen content in the pond has
enabled bass and bream to flourish and the pond has been the site
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of company fishing contests. When power failures have occurred
and septic conditions arose in the aeration tanks, the pond has
prevented such conditions from reaching the Suwannee River until
treatment processes were again in order.
Although, at this time, no change is contemplated in the pond,
aeration may have to be added to the pond if the increased waste
water load caused anaerobic conditions to develop. This could be
accomplished by means of submerged perforated polyethylene air
headers or floating surface aerators placed near the central inlet.
OUTFALL SEWER AND CLj FACILITIES (Sheet CE-6)
Since total flows are only expected to increase by 9-12% and
peak flows will actually be reduced, the existing facilities should
still be adequate.
F - PROPOSED MODIFICATIONS
AIR SUPPLY
The number of aeration sparjers in the aeration tanks will be
approximately doubled. To furnish the additional air required,
two more 75 HP Spencer turbo compressors will be added. Luring
operations, four will be running and one will be kept as a standby.
The motor control center near the lift station was originally
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designed to accommodate two more future blowers so only power
connections from the motor control center to the blower motors are
needed. The motor control center will also have a "Motor Minder"
added to it which will provide automatic sequential blower re-
starts in the event of a power failure. This device will also pro-
tect the 75 HP motors against low voltage and single phasing.
PLANT HYDRAULICS
Although peak flow rates will be reduced, the possibility of
aeration tank effluent trough overflows may still exist. New head
box and an increase in the aeration tank discharge line size to
18 inches from 14 inches should prevent any further problem.
BY-PRODUCT RECLAIM SYSTEM
The original system consisted of a collection sump in the fa-
cility lift station and a Moyno pump which returned the sludge and
grease collected by the primary settling (by-products) tank to the
cookers in the plant. Considerable sand and grit in the sludge
caused clogging in the return line which was sized for future flows
but in which present velocities failed to keep the grit and sand
in suspension. In addition, the by-products reclaimed often con-
tained too much water for economical recovery.
System improvements will include.
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1. Replace the present Moyno by-products pump with a 200 GPM -
35 ft. head float actuated non-clog centrifugal pump. This
will return by-products to the cookers with sufficient velocity
to prevent clogging of the return line.
2. Install a secondary grease tank in the by-products area of
the plant. This tank will receive grease from the by-products
tank skimmer box. This tank will permit reutilization of the
Moyno pump to draw grease from the bottom of the tank and dis-
charge to a separate grease cooker for separate rendering.
3. As an alternate to this scheme, possible use of a centrifuge
to thicken the sludge (20% solids) before discharge to the
cookers is being considered. If it proves practical to re-
claim secondary as well as primary sludge, this alternate will
appear to be more attractive.
SLUDGE DRYING FACILITIES
A modification to the sludge withdrawal system in the decant
well of the aerobic digester is required. An adjustable sludge
drawoff pipe should permit the operator to withdraw sludge from
that level in the decant well which contains the thickest sludge.
A new 100 GPM sludge drawoff pump on brackets secured to the
side of the aerobic digester will discharge to either one of the
75
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existing drying beds or to the new third sludge drying bed. As an
alternate, the discharge can be sent to the by-products sump.
Should the secondary sludge be amenable for reuse as poultry food,
there will be no need for sludge drying beds. Since secondary sludge
is low in protein compared to primary sludge, its reclaim value is
not yet proven.
CONDENSER COOLING WATER
The success of the waste treatment facility operation under the
increased loading anticipated is dependent on 100% reuse of process
waste water for by-product cooker vapor condenser cooling. To as-
sure an ample water supply, a 800-1,000 GPM, 50 psi, 75 HF pump will
be installed in the facility lift station. Taking its suction from
the process sump, it will discharge back through a new force main
to the by-product cooker vapor condensers.
During periods of low process waste flow, the drain valves
from the aeration tanks and aerobic digesters will be opened suf-
ficiently to maintain an adequate water supply to the condenser
cooling water pump. This will, in effect, convert the primary set-
tling tank (by-products collector) and aeration tanks to heat ex-
changers. Since some process waste (200 GPM minimum) always flows,
It is felt that the over one million gallons of aerated mixed li-
quor in the aeration tanks will not become heated to a point detri
mental to biological processes. Calculations indicate cooling water
76
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temperatures will remain below 120° F. for successful cooker vapor
condensation and such temperatures are not expected to injure bio-
logical process.
GREASE REMOVAL
By-product handling is, on occasion, hampered by excessive
grease in the reclaimed feed meal (conveyor fouling, clogging, etc.).
At the option of the poultry processor, a grease receiving tank will
be installed next to the by-products collector. Scum and grease
from this tank will be collected separately and pumped to a separate
cooker.
77
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