Waste
Treatment
Upgrading Meat Packing
Facilities to Reduce Pollution
EPA Technology Transfer Seminar Publication
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WASTE TREATMENT
Upgrading Meat Packing Facilities
to Reduce Pollution
ENVIRONMENTAL PROTECTION AGENCY* Technology Transfer
October 1973
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ACKNOWLEDGMENTS
This seminar publication contains materials prepared for the
U.S. Environmental Protection Agency Technology Transfer Program
and presented at industrial pollution-control seminars for the meat
packing industry.
This publication was prepared by W. James Wells, Jr., Paula B.
Wells, Charles A. Haas, Steve L. Hergert, and Steve J. Brown, of Bell,
Galyardt and Wells, Architects-Engineers, Omaha, Nebr.
NOTICE
The mention of trade names of commercial products in this publication is
for illustration purposes, and does not constitute endorsement or recommenda-
tion for use by the U.S. Environmental Protection Agency.
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CONTENTS
Page
Chapter I. Introduction ' 1
The Need for Wastewater Treatment 1
Micro-organisms and Their Role in Waste Treatment 2
Chapter II. Waste Loads from the Meat Packing Industry 5
Chapter III. Procedures in the Planning, Design, and Construction of a Wastewater-
Treatment System 9
Sampling the Waste 9
Development of Design Criteria t 9
Effluent Requirements 10
Development of Alternative Treatment Methods .11
Design of the Treatment System 11
Construction 12
Chapter IV. Wastewater-Treatment Methods for the Meat Packing Industry 13
Anaerobic Processes 13
Aerobic Lagoon Systems 17
Activated-Sludge Processes 21
Trickling Filters 25
Rotating Biological Disks 27
Irrigation Methods for the Meat Packing Industry 30
Chapter V. Operation and Maintenance of Waste-Treatment Plants 35
Chapter VI. Case Histories 39
American Beef Packers, Inc 39
Iowa Beef Processors, Inc., Denison 42
Farmland Foods 43
Iowa Beef Processors, Inc., Dakota City 51
Lykes Brothers Packing Plant 56
Chapter VII. Survey of Existing Waste-Treatment Facilities for the Meat-Processing Industry . 63
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Chapter I
INTRODUCTION
THE NEED FOR WASTEWATER TREATMENT
The discharge of industrial wastewater recently has become a significant area of concern as
public regulating bodies have become increasingly involved with the establishment of water quality
criteria. Many types of substances, when discharged into a receiving body of water, degrade the
water quality to such an extent that beneficial uses of the stream are no longer attainable. While no
one industry will pollute a stream with all types of damaging substances, sufficient quantities or
combinations of even a few pollutants can cause irreparable harm.
The major components present in industrial waste discharges that have a pollution potential
are solids (floating, suspended, settleable, and dissolved), organic matter, nutrients, temperature
change, toxic substances, and acids and alkalis.
Floating solids, including grease and scum, are not only unsightly; they may adversely affect
natural aquatic characteristics, such as oxygen transfer and light penetration. Settleable solids may
have an adverse effect on stream organisms by covering up the stream bed and forming sludge
blankets that will decompose anaerobically with the formation of odorous gases. Settleable solids
may also prevent fish hatching on the stream bed, and may create an anaerobic environment that
will hamper bottom dwelling microscopic animals. Suspended solids will give the water a turbid
complexion limiting light penetration, which in turn hampers aquatic vegetation relying on photo-
synthetic reactions for survival. Large amounts of suspended solids will also increase the require-
ments for treatment if the water is to be used for domestic supply.
Organic matter discharged into a watercourse will decompose, depleting the dissolved oxygen
(DO) supply available in the water. When such oxygen depletion occurs, definite changes will
occur in the composition of the organisms that inhabit that particular reach of stream. The more
desirable species of fish (trout, bass, etc.), which require DO levels near 5 mg/1 or greater, will
disappear to be replaced by the coarser types (such as carp and bullheads), which can survive DO
levels near 2 mg/1. Below the 2-mg/l level, however, fish life will cease to exist. Other forms of life
react in a similar manner to decreasing levels of DO, and a shift toward anaerobic species eventually
will occur in the affected area. Only physical processes, such as the natural reaeration of flowing
water, will help the stream to recover from its oxygen-depleted state.
Nutrient-rich waste flows are causing increasing concern as excessive algae growths become
unacceptable. The two major nutrients commonly found in many types of industrial discharge are
nitrogen and phosphorus. Presence of these nutrients may cause excessive growth of algae. When
these heavy algae growths die, they exert an oxygen demand that, in turn, may cause fish kills,
unpleasant odors, and an undesirable taste. The effective use of a body of water for recreational
and domestic purposes is diminished greatly by algae growth.
Temperature changes in water may cause adverse changes in the organisms and affect stream
reaeration. Fish and other forms of aquatic life have preferred temperatures at which their life
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processes are at an optimum. When temperatures deviate from the optimums, the organisms will
not flourish and may disappear entirely. In addition to long-term alteration of temperatures, rapid
changes in temperature are harmful. Moreover, deviation to higher than normal temperatures lowers
the stream's ability to reaerate itself by limiting the amount of DO at saturation.
Toxic chemicals are common constituents of some types of industrial processes, and, therefore,
find their way into the waste stream. Such toxic substances may be harmful to both plant and
animal life, and may leave the water unsuitable for recreation and human consumption.
Acidity and alkalinity, as measured by pH, are also a factor to be considered in stream quality.
Because the pH of most industrial discharges varies from neutral, effluents must be checked and
often adjusted before being discharged into a stream.
To avoid degradation of water quality, industrial waste treatment must be practiced in some
form. This form may be complete treatment at the industrial plant or partial treatment before dis-
charge to a municipal sewer system. The degree of treatment required is contingent upon Federal
and local requirements, which establish effluent standards for a particular receiving body of water.
MICRO-ORGANISMS AND THEIR ROLE IN WASTE TREATMENT
Treatment of industrial wastes is accomplished by living systems. The waste flow furnishes
food and environment to a mixed culture of micro-organisms that break down the organic constit-
uents of the waste and remove it from solution. The basis of adequate treatment is the 'proper
control of the biological environment to make it possible for the organisms to function at the
desired level.
The most important organisms in waste treatment are bacteria—the simplest form of living
matter. Bacteria may be heterotrophic (using organic compounds as a carbon source) or autotrophic
(using carbon dioxide as a carbon source). Heterotrophs may be aerobic, requiring free DO; faculta-
tive, functioning with or without free oxygen; or anaerobic, requiring complete absence of oxygen.
Other organisms of importance are fungi, protozoa, and rotifers (higher level animals that feed on
bacteria and play an important part in activated sludge). Algae, which are important in some waste-
treatment systems, are autotrophic, photosynthetic plants, relying on carbon dioxide and sunlight
to carry out their biochemical reactions.
The breakdown of organic wastes is a complex process involving complicated biochemical
reactions. The process by which cells remain viable and obtain energy for synthesis and respiration
is called metabolism. Fbr heterotrophic aerobic bacteria, the large molecules that make up the
food supply must first be hydrolyzed, with carbohydrates going to sugars, protein to amino acids,
and fats to fatty acids. These products then can be used by the cells for assimilation.
Anaerobic reaction involves the breakdown of organics to intermediate products (chiefly
organic acids) by one set of bacteria, and the use of these products as food by methane-forming
bacteria that further break down the waste. These bacteria require higher temperatures to live than
do aerobic bacteria, and are called thermophilic. Compared to aerobic processes, anaerobic
reactions will not yield as much energy and breakdown will be incomplete.
Metabolism to insure growth is important because the maximum rate of metabolism results in
the maximum growth rate for the organisms. That is to say, the greatest removal of organics occurs
at the time of greatest growth.
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In summary, aerobic processes are characterized by complete metabolism and large biological
growth, while anaerobic processes are characterized by small growth, incomplete metabolism, and
creation of high-energy end products.
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Chapter II
WASTE LOADS FROM THE MEAT PACKING INDUSTRY
A definite analysis of the waste characteristics of the meat packing industry is not a simple
matter. It is difficult to characterize a typical plant and its associated wastes, owing to the many
procedures and facets of meat-processing operations. A given plant may perform many of only a
few of these procedures. For all practical purposes, however, the industry may be divided into
three categories, as follows:
• Slaughterhouses (killing and dressing)
• Packinghouses (killing, dressing, curing, cooking, etc.)
• Processing plants (processing with no killing operation)
Typical slaughterhouse and packinghouse wastes are generally high in 5-day biochemical
oxygen demand (BOD5), total suspended solids, floatable material, and grease. Furthermore, the
waste is generally at an elevated temperature and contains blood, bits of flesh, fat, manure, dirt,
and viscera. Important processes such as blood recovery, grease recovery, separate paunch manure
handling, and efficient rendering operations can reduce waste loads substantially and may also
produce salable by-products. In addition, a well-managed program of in-plant housekeeping
practices is desirable, both from a sanitary and waste-load standpoint.
Table II-1 gives waste loads that have been found, through extensive study and research of
records, to be typical of various types of meat packing plants. A widespread sampling program
currently is being conducted for the Environmental Protection Agency by the North Star Research
and Development Institute, for the purpose of supplementing and updating these data.
Table 11-1 .—Standard raw waste loads
Type
Slaughterhouse, per 1,000 pounds LWK1
Packinghouse, per 1,000 pounds LWK1
Processing plant, per 1,000 pounds product
Flow,
gallons
696
1 ,046
1 265
BODS,
pounds
5.8
12.1
5.7
SS,
pounds
4.7
8.7
2.7
Grease,
pounds
2.5
6.0
2.1
1 LWK indicates live weight kill.
SOURCE: Industrial waste study by the North Star Research and Development Institute for the Environmental Protection
Agency.
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Table I \-2.-Unit waste loadings for meatpacking plants
Type of animal slaughtered
Hogs
Hogs
Mixed
Hogs
Cattle
Hogs
Hogs
Mixed
Hoqs
Mixed
Cattle
Mixed
Mixed
Mixed
Mixed
Mixed
Average
BODS
Suspended
solids
Nitrogen
Grease
Pounds per 1,000 pounds of live weight
18.0
15.0
12.7
13.1
20.8
15.7
10.5
19.7
9.8
16.7
10.0
14.7
6.5
19.2
8.9
21.6
14.6
12.0
9.1
4.6
9.8
14.8
14.8
10.0
9.4
7.2
15.0
11.0
13.2
6.2
'11.2
10.8
21.7
12.0
2.67
1;29
2.02
1.25
2.24
2.01
1.02
2.59
1.46
2.18
1.08
1.70
.79
2.10
.89
1.82
1.70
0.90
2.30
1.44
2.83
.68
1.79
1.00
.60
.27
2.00
.55
1.5
.5
2.1
(')
6.0
1.63
1 Data missing.
SOURCE: "An Industrial Waste Guide to the Meat Industry," U.S. Department of Health, Education, and Welfare,
Washington, D.C., 1965.
The values listed for slaughterhouses apply only to medium-sized plants that slaughter from
95,000 to 750,000 pounds per day and do very little or no processing of edible by-products, perform
dry inedible rendering and do no blood processing, or dry blood in such a manner as to produce no
blood water. The values listed for packinghouses apply to most medium or large plants that carry
out all processes associated with slaughtering, cutting, rendering, and processing. Values for
processing plants represent plants that cut and process meat, but do no slaughtering or rendering.
The values given are in general agreement with other values found in the literature, although
the variations may have a wider range. Table II-2 shows the characteristics of the waste flow from 16
cattle and hog packing plants, illustrating a typically wide variation from plant to plant.
In general, the processes undertaken at a packing plant have a much greater effect on the waste-
load factors than the size of the plant.
A limited number of studies have attempted to analyze the component parts of the process.
Because such wide variations in raw waste loads do exist, data obtained from actual sampling of
wastes similar to those anticipated are extremely useful and often economically beneficial in
designing waste-treatment facilities.
Table II-3 presents a typical source breakdown of hog packinghouse wastes. Packing-plant
wastes are of an organic nature, and treatment may be accomplished by many different systems of
biological treatment.
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Table \\-3.-Analyses of major components of waste from hog packinghouses
Source of flow
Killing department
Blood and tank water
Scalding tub .
Hog dehairing
Hair cook water
Hair wash water
Meatcutting
Gut washer
Curing room
Curing room showers
Cured meat wash
Pickle
Sausage and miscellaneous
Lard department
By-products
Laundry
Concentration, mg/l
Solids
Total
1,840
44,640
13,560
1,540
4,680
7,680
2,840
22,600
26,480
34,100
9,560.
140,000
11,380
820
4,000
18,620
Suspended
220
3,690
8,360
560
80
6,780
610
15,120
1,800
1,720
920
(')
560
180
1,380
4,120
Nitrogen
Organic
134
5,400
1,290
158
586
822
33
643
83
255
109
2,750
136
84
186
56
NH3
6
205
40
10
30
18
2.5
43
12
25
17.5
37
4
25
50
5
Clas
NaCI
435
6,670
640
290
290
230
1,620
360
19,700
29,600
6,200
77,800
880
230
1,330
(')
BOD5
825
32,000
4,600
650
3,400
2,200
520
13,200
2,040
460
1,960
18,000
800
180
2,200
1,300
pH
6.6
9.0
9.0
6.7
(M
6.9
7.4
6.0
7.3
6.7
7.3
5.6
7.3
7.3
6.7
9.6
1 Data missing.
SOURCE: "An Industrial Waste Guide to the Meat Industry," U.S. Department of Health, Education, and Welfare,
Washington, D.C., 1965.
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Chapter III
PROCEDURES IN THE PLANNING, DESIGN, AND
CONSTRUCTION OF A WASTEWATER-TREATMENT SYSTEM
SAMPLING THE WASTE
When a meat packing plant undertakes the task of providing treatment for its wastewater, one
of the first steps is to determine the characteristics of the waste flow. As mentioned earlier, meat
packing wastes vary considerably from plant to plant. Consequently, it is important to set up a
sampling program to determine the specific nature of the flow for which the treatment facilities
are to be designed.
Sampling stations should be established at all accessible points of waste discharge, and samples
should be taken at half-hour intervals continuously for 3 days, and preferably 1 week. These samples
should be combined for every 24-hour period to provide an accurate composite of the waste. A
weir, or similar measuring device, should be installed at each sampling station to provide a means of
determining the rate of flow when each sample is taken. The sampling bottle must be kept chilled
during the sampling period, and should be delivered to the testing laboratory as quickly as possible
at the end of each 24-hour interval.
It is important that the laboratory selected to perform the tests be experienced in analyzing
wastewater samples. The most frequently performed determinations are 5-day biochemical oxygen
demand (BOD5), chemical oxygen demand (COD), settleable solids, suspended solids, volatile
suspended solids, grease, Kjeldahl nitrogen, and pH.
DEVELOPMENT OF DESIGN CRITERIA
Once the results of the sampling program have been reviewed and analyzed fully, the design
engineer can establish the design criteria. These factors are usually determined on the basis of
1,000 pounds of live weight kill or per head. Any anticipated change in slaughtering or processing
operations must be considered, as current waste characteristics will be affected. If flows and BOD
appear to be excessively high as sampled, a conscientious review of waste conservation and in-plant
housekeeping programs should be made, with the goal of reducing these values to more generally
acceptable values.
The following design factors are determined from sampling data:
• Design average flow, gallons per 1,000 pounds of live weight per day
• Design maximum flow, gallons per day
• Design BOD, pounds per 1,000 pounds live weight kill
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• Design suspended solids, pounds per 1,000 pounds live weight kill
• Design workweek, days per week
EFFLUENT REQUIREMENTS
Environmental Protection Agency Guidelines
As required by Public Law 92-500,a the U.S. Environmental Protection Agency is preparing
effluent guidelines for discharges by the meat-processing industry. The guidelines are based upon
the application of the "best practicable control technology currently available." These guidelines
are to be promulgated by October 18,1973,1 year from the date of enactment of the law. As
guidance until that date, interim guidelines have been prepared by the EPA Permit Program. These
values are listed in table III-l.
State Requirements
Public Law 92-500 allows the State to establish standards that are more stringent than the
Federal guidelines. State effluent requirements may therefore vary considerably throughout the
country and within an individual State, depending on the water quality standards for the receiving
stream into which the treated wastewater will be discharged. In some States, tertiary treatment is
already required on some streams and lakes, with BOD5 and suspended solids limitations of 5 mg/1
or less.
Municipal Requirements
Most municipalities have ordinances that place limitations on the characteristics of the waste-
water that may be discharged into the municipal sewer system. These limitations are set to prevent
operational problems at the municipal waste-treatment facility and to prevent the plant from becoming
overloaded. Any industry failing to meet this limiting value must pay a surcharge. Because of the
high flows and concentrated wastes discharged from a meat packing plant, it is generally necessary
to pretreat these wastes to a degree that will permit the municipality to handle them. Also, further
Table 111-1 .—EPA interim guidelines for meat-processing discharges
Meat processing
Slaughterhouse
Packinghouse
Processing plant only
BODj1
0.17
.26
.26
Suspended solids1
0.23
.35
.26
1 Values expressed in terms of pounds per 1,000 pounds of live weight
killed.
SOURCE: "Effluent Limitation Guidance for the Refuse Act Permit
Program," Washington, D.C., Environmental Protection Agency, July 27, 1972.
*92d Cong., Oct. 18,1972.
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reduction of BOD and suspended solids would be economically advantageous. Screening, grease skim-
ming, and solids removal are perhaps the most important initial types of pretreatment. In some cases,
waste flow must also be treated biologically in order to meet BOD limitations.
When a municipality builds or expands its waste-treatment facility, the industries are expected
to pay their share of the construction and operational costs. These costs can become high, particular-
ly in smaller communities where the industrial flow is a substantial percentage of the total. In these
cases, the economics of extensive pretreatment, partial treatment, or completely separate and
industry-owned waste-treatment facilities must be studied carefully.
DEVELOPMENT OF ALTERNATIVE TREATMENT METHODS
Once design criteria and effluent requirements have been established, various methods of waste
treatment that will provide an effluent meeting those standards are investigated by the design engineer.
Several additional factors must be considered in making a choice. These factors include land availa-
bility, proximity to residential or commercial areas, initial construction cost, operation and mainte-
nance costs, and ease of operation. Meat packing plants located in a built-up area will have fewer
options to consider, since available space will be at a minimum. It is wise to be in contact with State
regulatory agencies at this stage of the design. Preliminary submittal of the selected treatment scheme
for approval of design criteria and layout will facilitate later review by these agencies.
DESIGN OF THE TREATMENT SYSTEM
The design engineer begins preparation of final plans and specifications for construction once
the selection of the treatment system is made. At this stage, it is important to obtain reliable topo-
graphical information that provides ground elevations, location of existing property lines, building,
and sewers, sewer invert elevations, and a benchmark elevation on which to base proposed construc-
tion. Where a large area is involved, an aerial survey is often the most efficient way to obtain this
information. The design engineer must also check the availability of utilities and electrical service at
the site, as well as the power characteristics that should be used in specifying equipment.
Once the treatment units have been sized an overall site layout can be developed, leaving ade-
quate room between structures for access and maintenance. This layout will include utilities and
wastewater piping, site grading, and other site improvements. It is essential that future expansion
and upgrading of the system be considered in making the layout, permitting additions to be made
to the facilities with minimum disruption of the existing treatment system. Sewer outfall lines can
often be designed with extra available capacity at little additional cost.
Final plans and specifications will include all structural, electrical, and mechanical work
required to complete the project. Equipment drawings and specifications generally are prepared
in such a manner as to permit various manufacturers to bid on the units, and installation details are
provided with shop drawings furnished after award of contract.
When the plans and specifications are complete, the design engineer prepares for the owner
an estimate of the construction cost. The final design documents are then submitted to the State
environmental regulatory agency for review and approval leading to issuance of a permit for
construction.
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CONSTRUCTION
As soon as a permit has been granted by the State, the project can be advertised for bids. A
notice describing the project is made available to qualified contractors in the vicinity, and plans and
specifications are issued to any of these contractors, upon request, for a period of 3 weeks to a
month. Sealed bids are then opened by the owner or his representative on a specified letting date.
Award of contract is usually made to the low bidder, contingent upon the recommendation of the
engineer.
The construction phase of the project should be subject to periodic inspection by the design
engineer or other qualified personnel hired by the owner. Careful conf ormance of construction with
plans and specifications is essential for correct and reliable functioning of the system. Any deviation
from the contract documents should be made only with the approval of the design engineer. Equip-
ment shop drawings should also be routed to the engineer for review and approval.
When construction has been completed, the contractor should put the facility into operation for
a brief period of observation, during which time the owner and the design engineer should inspect
the project for final acceptance.
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Chapter IV
WASTEWATER-TREATMENT METHODS FOR THE
MEAT PACKING INDUSTRY
The secondary treatment methods commonly used for the biological treatment of meat-
processing waste flows include the following:
• Anaerobic processes
• Aerobic lagoon systems
• Variations of the activated-sludge process
• High-rate trickling filters
• Rotating biological disks
All of these treatment processes are capable of providing complete treatment and can achieve BOD
reductions of 70-95 percent and suspended solids reductions of 80-95 percent. Each system has
advantages and disadvantages; generally, the degree of treatment required, together with site location
and limitation, capital costs, and operational costs, will dictate the selection of the treatment system.
There follows a discussion of each system describing the treatment process and equipment used, as
well as advantages and drawbacks. In addition, disposal of treated wastewater by irrigation methods
is discussed as an alternative to tertiary treatment.
ANAEROBIC PROCESSES
Treatment by the anaerobic process is often used for wastes originating from meat-processing
plants, because the nature of the waste lends itself to this type of biological activity. Elevated
temperatures (85°-95° F) and high concentrations of BOD and suspended solids—typical character-
istics of the waste flow from a meat packing plant—are necessary for successful anaerobic treatment.
As discussed earlier, anaerobic bacteria, which function in the absence of free oxygen, break down
organic waste into gases (primarily methane and carbon dioxide) through production of intermediate
acids. When compared to aerobic processes, the rate of removal and sludge yield are small. Never-
theless, anaerobic treatment often proves to be a highly economical method for removing substantial
amounts of BOD and suspended solids.
Two types of anaerobic treatment are commonly used, anaerobic lagoons and anaerobic contact
units.
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Anaerobic Lagoons
Anaerobic lagoons are used widely for treatment of meat packing wastes, and function extreme-
ly well when the wastes have the desired characteristics. Typically, meat packing wastes have a high
quantity of fats and proteins, high concentrations of nutrients, and an elevated temperature—all of
these are essential for good anaerobic biological treatment.
Such lagoons are designed with a low surface-to-volume ratio to conserve heat in the pond.
Depths are much greater than for aerobic ponds, ranging from 12 to 17 feet. Loadings range from
12 to 25 pounds BOD per 1,000 ft3, with 15 to 20 pounds BOD per 1,000 ft3 frequently used in
meat-processing waste applications. A typical anaerobic lagoon system consists of one or more
square or rectangular ponds with a depth of 15 feet and an inlet near the bottom. A layer of sludge
on the bottom of the lagoon, containing active micro-organisms, comes in contact with the incoming
waste. Excess grease floats to the surface and forms a scum layer or grease cover, which serves to
both retain heat and restrict odors. Recirculation generally is not considered necessary, although it
has been used in some installations.
The following site conditions must be evaluated when considering anaerobic lagoons:
• Proximity to residential or commercial areas where potential odors may cause a nuisance—
one-quarter mile distance from any single-family dwelling is usually considered minimum,
and at least 1/2 to 1 mile from any residential area, preferably downwind
• Soil conditions—i.e., location of the ground water table and nature of the soil with respect to
workability and impermeability
It is essential that a natural cover be developed as soon as possible after the lagoon is placed in
operation, particularly in northern climates. The cover will minimize odors and assure adequate heat
retention. Recently, concern with air pollution has resulted in consideration of artificial covers for
odor control.
A natural cover will usually form if enough grease is present in the waste. To accelerate develop-
ment of a cover, paunch manure or normally recovered grease may be bypassed to the lagoon for a
short period. Because high winds may disturb the scum layer and result in heat loss and odor prob-
lems, a windbreak, such as a board fence sheltering the lagoon from high prevailing winds, may be
advisable to keep the natural cover intact. Low pH may affect adversely the formation of a natural
cover, and the influent may require some pH adjustment.
Styrofoam, polyvinyl chloride, and nylon-reinforced Hypalon have been used as artificial
covers, and other materials currently are being investigated. An adequate gas collection system to
trap the methane gases that rise to the surface is a major consideration in constructing a cover. Also,
sunlight and wind action on the cover will affect the life of the cover, depending upon the material
selected.
Properly designed inlet and outlet structures are important to successful functions of the anaer-
obic lagoon system. Good operation has been achieved with a feed inlet near, but not on, the bottom.
The effluent piping should be near the surface, and should be designed to prevent short circuiting
and disturbance of the grease cover.
Studies have indicated that solids do not accumulate to any significant extent in anaerobic
lagoons, but reach a state of equilibrium. Consequently, solids removal is not a maintenance
problem.
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Advantages of an anaerobic lagoon system are low initial cost, ease of operation, ability to
accept shock loads while continuing to provide a consistent quality effluent, and ability to handle
large amounts of grease. Problems may arise if a sufficient cover cannot be maintained and odors
result.
Where water used for meat processing is high in sulfates, waste flows cannot be treated in
anaerobic lagoons. Oxygen is stripped from sulfates by anaerobic bacteria, and hydrogen sulfide
is produced, causing severe odor problems as the gas is released to the atmosphere.
It should also be noted that the effluent from an anaerobic lagoon system generally contains
up to 100 mg/1 of ammonia nitrogen. The presence of ammonia nitrogen is toxic to fish in concen-
trations of 3-5 mg/1, depending upon pH, and water quality standards in most States limit the con-
centration to 2-5 mg/1. Consequently, the secondary treatment method selected to follow the
anaerobic lagoon system should provide for nitrification of the ammonia nitrogen where water
quality standards place this limitation.
The anaerobic lagoon system will not produce an effluent suitable for discharge into a stream
without further treatment. It is highly efficient as a first-stage treatment unit and generally is
followed by some form of aerobic system. Some States, however, will not permit the use of anaer-
obic lagoons or are requiring that they be provided with a cover.
Figures IV-1 to IV-3 show anaerobic lagoon facilities for three waste-treatment facilities.
Figure IV-1. Anaerobic lagoon, Iowa Beef Processors, Inc., Denison.
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Figure IV-2. Anaerobic lagoon. Farmland Foods.
Figure IV-3. Anaerobic lagoon, Iowa Beef Processors, Inc., Dakota City.
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Anaerobic Contact Process
The anaerobic contact process consists basically of an anaerobic digester with mixing equip-
ment, a degasification-system, and a clarifier. Solids from the digester are sent to a degasifier in
order to minimize floating material, and are then settled, with sludge from the clarifier being
returned to the raw waste line. The separation and recirculation of seed sludge permits short
retention periods, ranging from 6 to 12 hours. Solids retention time for a high degree of treatment
is approximately 10 days at 90° F. As the operating temperature drops, the solids retention time
must be increased. ,
Control of pH is essential to insure proper operation, and lime or sodium bicarbonate is
commonly used to raise the pH of the raw wastes. Inorganic salts in high concentrations may be
toxic to the anaerobic organisms. ~"\^
Anaerobic contact digester units are loaded in the range of 0.10 to 0.20 pound BOD per
cubic foot per day at approximately 90°-95° F. Flow equalization is employed in^ order to main-
tain a uniform feed rate to the digester. This practice is necessary because of the short contact
time involved in the process. Either draft tube or turbine-type mixers are used to provide complete
mixing. Digester gas may be used to heat the digester. ""\.
The degasification step may be accomplished by vacuum degasification or air stripping. In
vacuum degasification, a vacuum of 20 inches of mercury is maintained in a vessel that has a
diameter equal to its length. The influent is elevated to the top of the vessel and cascaded down
over slotted trays with removed gases sent to a waste gas burner. The air-stripping process involves
passing diffused air through the waste to scrub off the gas. This method is less expensive, but it has
more operational problems than the vacuum process.
The clarifier receiving the sludge should be provided with a well-designed recirculation system
to move the light floe and to avoid a temperature loss.
Treatment efficiencies of 85-93 percent removal of BOD can be obtained with the anaerobic
contact system, but usually additional aerobic treatment is required. The overall cost of such a
system usually lies between that of an anaerobic lagoon system and an activated-sludge plant.
An anaerobic contact system is currently in use at the Wilson Certified Foods, Inc., plant in
Albert Lea, Minn. This facility consists of a flow-equalizing basin, two digesters of approximately
12 hours' detention time, loaded at 0.156 pound BOD per cubic foot per day, two vacuum degasi-
fiers, two sludge separation units (clarifiers), and two oxidation ponds receiving the separation
effluent. The separators are designed for a detention time of 1 hour, based on total flow including
recirculation. The recirculation rate is approximately one-third of the raw waste flow.
Table IV-1 presents actual operating data taken from the Wilson anaerobic contact system.
BOD removal is approximately 91 percent through the anaerobic contact process and 98 percent
in the stabilization ponds. Good removals (80 percent) are also obtained for suspended solids.
Lagoon treatment provided after the contact process is lowering the effluent concentrations to
acceptable levels and is an essential segment of the total treatment system.
AEROBIC LAGOON SYSTEMS
Treatment of domestic and industrial wastes, including those from meat packing plants, fre-
quently is accomplished in aerobic lagoons. Two types of lagoons generally are classified as being
17
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Table IV-1 .-Anaerobic contact system, Wilson Certified Foods, Inc., Albert Lea, Minn..
average operating data for all killing days in 1960
Component
BOD
Suspended solids
Suspended volatile solids . . ....
Total solids .... ....
Total solids water supply . . .
Total solids after deducting TS in
water supply
Total volatile solids
Total volatile solids in water supply ....
Total volatile solids after deducting
TVS in water supply
Raw waste1
mg/l
1,381
998
822
2,100
560
2,540
1,700
300
1,400
Pounds
16,220
11,610
10,370
36,500
6,500
30,000
19,980
3,520
16,460
Anaerobic process
effluent1
mg/l
129
198
153
2,080
560
1,520
800
300
500
Pounds
1,517
2,325
1,800
24,450
6,500
17,950
9,400
3,520
5,880
Plant effluent
corrected for
seepage2
mg/l
26
23
20
1,076
560
516
367
300
67
Pounds
304
268
232
12,500
6,500
6,000
4,310
3,520
790
1 Flow, 1,410,000 gallons.
2 Pond effluent, 772,000 gallons; loss in pond, 638,000 gallons.
SOURCE: "An Industrial Waste Guide to the Meat Packing Industry," U.S. Department of Health, Education, and Welfare,
Washington, D.C., 1965.
aerobic: aerated lagoons, which mechanically introduce oxygen by aeration; and oxidation ponds,
which are lightly loaded and rely on sunlight and wave action to accomplish bio-oxidation and
photosynthesis. Aerobic lagoons are used frequently to provide additional treatment to the effluent
from an anaerobic lagoon system. An example of an aerobic lagoon appears in figure IV-4.
Aerated Lagoons
Aerated lagoons usually are designed with detention times of 2-10 days, have liquid depths of
8-15 feet, and use some type of aeration equipment—either fixed mechanical turbine-type aerators,
floating propeller-type aerators, or a diffused-air system.
In most cases, not enough turbulence is maintained in the basin to maintain the solids in
suspension, and those solids that settle may be degraded anaerobically on the bottom. In those
instances where sufficient turbulence does exist, the system approaches the conditions of an extended
aeration system without sludge return.
BOD removal in aerated lagoons depends on temperature, detention time, and influent waste
characteristics. Treatment efficiency decreases as temperature decreases. In northern climates,
lower BOD reduction is experienced during the winter months. Aerated lagoons treating meat
packing wastes generally are designed to achieve an average BOD reduction of 50-60 percent.
Power requirements are a major consideration. Treatment facilities handling a high industrial
flow may use several hundred horsepower. Facilities for small meat-processing plants may use no
more than 20 hp.
18
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Figure IV-4. Aerobic lagoon, Iowa Beef Processors, Inc., Denison.
When aerated lagoons are used in series with anaerobic lagoons, sufficient oxygen is added to
restore the waste to an aerobic state, including oxidation of sulfides, and to provide for the additional
biological treatment.
The most significant advantage of an aerated lagoon system is its relatively small land require-
ment. The high cost or unavailability of land can easily offset the higher operational cost of the
aerated lagoon system. There is, however, only a minimum reduction of ammonia nitrogen in an
aerated lagoon. Furthermore, aerated lagoons must always be followed by an oxidation lagoon to
capture the suspended solids and to provide additional treatment.
Oxidation Ponds
Oxidation ponds consist of relatively shallow, lightly loaded lagoons (20-40 pounds of BOD
per acre) with detention times often as long as several months. They will provide a high degree of
BOD reduction and have been used widely in the past for both domestic and industrial wastes. As
effluent quality requirements become more stringent, however, the treatment efficiency achievable
in oxidation ponds may be inadequate for discharge into a particular receiving stream. In areas
where the effluent would flow into a recreational body of water, the BOD and suspended solids
must be reduced in some States to 5 mg/1 or less, and ammonia reduced to less than 3 mg/1.
Even when effluent requirements are less stringent, problems may develop due to the develop-
ment of algae growth on the lagoon surface. The algae escape with the pond effluent and create
an undesirable appearance, odor, and taste in the receiving stream.
Oxidation ponds that treat wastes from the meat-processing industry frequently are preceded
by anaerobic lagoons or anaerobic lagoons in conjunction with aerated lagoons. Even with this
19
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prior treatment, the BOD remaining in the flow entering the oxidation pond may still be substantial.
Since the loading rate to oxidation ponds generally is kept quite low to minimize odor problems
and to provide for a high degree of treatment, large areas of land are necessary to provide adequate
surface area for the wastewater.
The water depth in oxidation ponds varies usually from 4 to 8 feet. Frequently a level-control
system is provided to permit rapid discharge of the effluent during periods of higher flow in the
receiving stream, dropping the water level to a minimum of 2 feet before cutoff of discharge and
temporary storage.
Loadings for oxidation ponds are expressed in pounds of BOD per acre of water surface.
Generally accepted values for industrial ponds range from 20 to 40 pounds per acre, with 25 to 30
pounds per acre being a commonly used design loading. Loadings as high as 100 and 150 pounds of
BOD per acre have been used for meat-processing wastes with reasonably high initial treatment effi-
ciencies; however, odor problems usually have occurred and the quality and efficiency of the lagoons
frequently have deteriorated after a period of several years. For this reason, State and Federal health
officials are increasingly reluctant to approve these high loading rates, and engineers no longer
recommend them.
Suitable soil conditions are of basic importance to stabilization pond design, as it is essential
that the compacted earth below the maximum water surface be essentially impermeable. Sandy or
other granular soils are unsuitable for lagoon construction and require some type of liner. Owing
to the extensive surface area involved, lining of large stabilization ponds with any material other
than clay soils found in upper soil layers or nearby excavation is usually prohibitive in cost. Smaller
ponds may be sealed or lined with bentonite or some type of vinyl or asphalt liner.
\,
\
It is usually unnecessary to chlorinate the effluent from a stabilization pond, although such
chlorination may be required whenever effluent standards for pathogenic bacteria are not met.
The large surface area required for adequate treatment of meat-processing wastes often results
in ponds sufficiently large to have significant wave action and accompanying erosion of dikes.
Riprap is often placed on those dikes subject to the wave action caused by high winds. Continuous
maintenance of the dikes is essential for good operation, as excessive weed growth will lead to septic
areas and mosquito breeding, stnd weakening of dikes caused by erosion or burrowing by rodents
can result in potential flooding of surrounding land.
The configuration of stabilization ponds is generally rectangular, with acute angles avoided to
prevent dead areas. Inlet and outlet structures are placed to prevent short circuiting of the flow
through the lagoon. Two or more ponds may be used in parallel to avoid the excessive unbroken
surface area of one large pond. Oxidation ponds are often constructed in series to provide succeed-
ing degrees of treatment. Stabilization ponds that follow anaerobic or aerated lagoons generally
will have an average efficiency of approximately 80 percent (in the first stage), and as high as 90
percent in the summer and 70 percent or less in the winter months. Efficiency tends to drop off
somewhat in successive stages, reaching as low as 50 percent in a third-stage aerobic pond.
Stabilization ponds provide an excellent means of treating meat-processing wastes before use
of the wastewater for irrigation purposes. Owing to increasingly stringent effluent quality stand-
ards, however, the discharge from a stabilization pond frequently may not be satisfactory for
discharge into a receiving body of water.
20
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ACTIVATED-SLUDGE PROCESSES
Probably one of the most efficient and widely used systems of biological treatment of waste-
water is the activated-sludge process. Aeration of wastewater containing biologically degradable
material in the presence of micro-organisms produces a mass of settleable solids known as activated
sludge. Stabilization occurs as organic matter in the wastewater is used as food by the micro-
organisms. There are several variations of the activated-sludge process, four of which are shown in
figure IV-5 and all of which are described in the sections that follow.
Conventional Activated Sludge
The conventional activated-sludge process is composed of four functional steps.
• Primary sedimentation to remove settleable solids
• Aeration of a mixture of waste and biologically active sludge
• Separation of the biologically active sludge from the treated waste by sedimentation
• Recycle of this settled biological sludge
Following sedimentation in a primary clarifier, the wastewater is mixed with recycled sludge in
an aeration basin (see figs. IV-6 and IV-7). This procedure insures that adequate numbers of
SLUOGt
THICKEMI
DIGESTION
SETTLED
WASTES
r
r
-J
*-
SECONDARY
CLARIFIER
RETURN SLUDGE
EFFLUENT^
WASTE EXCESS
SLUDGE
BASIC SYSTEM
STEP AERATION
RAW
WASTES
WASTE EXCESS
SLUDGE
(SMALL OR NONE)
CONTACT STABILIZATION
EXTENDED AERATION
Figure IV-5. Variations of the activated-sludge process.
21
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Figure IV-6. Aeration basin, American Beef Packers, Inc.
Figure IV-7. Aeration basin, Lykes Brothers Packing Plant.
22
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micro-organisms are present to carry out the degree of waste stabilization desired. In the aeration
basin the mixture of wastewater and recycled sludge is a.erated for a specified length of time to pro-
vide an aerobic environment for the biological oxidation of the organic matter present. Final
sedimentation following this aeration allows the activated sludge to settle, producing both a clear
effluent, low in organic content, and a biologically active sludge for recycle.
The conventional process is capable of achieving BOD reductions of 90-95 percent and can
produce a stable effluent with little nitrification.
The conventional activated sludge is affected adversely by the occasional spills or dumps of
high organic wastes, such as blood. Also, the widely varying flows can be troublesome.
Owing to problems encountered in the basic activated-sludge system when dealing with a
particular waste or when a higher degree of treatment is desired, a number of modifications have
been devised.
Tapered Aeration and Step Aeration
In the basic activated-sludge system, air requirements decrease as flow proceeds through the
aerated basin. Two systems, the tapered-aeration system and the step-aeration system, have been
devised to match the oxygen supply with the oxygen demand.
The tapered-aeration system provides for the introduction of air to the aerated basin in
decreasing amounts in an attempt to match the air applied with the air requirements of the system.
Reducing the air applied in no way affects the biological process in the basin so long as sufficient
amounts of air are present. The procedure does, however, increase the air application efficiency,
as only that air actually required is supplied to the basin.
The step-aeration system splits the wastewater flow to the aerated basin and feeds it separately
at different points along the aeration basin. The return activated sludge is introduced with the first
portion of the raw waste at the head of the basin. Step aeration evens out the air requirements over
the length of the tank, allowing higher BOD loadings, shorter detention times, and more efficient
use of applied air.
Contact Stabilization
The BOD in sewage is rapidly adsorbed by micro-organisms after initial contact between waste
and organisms. In the conventional activated-sludge system, the time and air necessary to stabilize
this adsorbed material is provided in the same tank where original contact between waste and
organisms was made.
The contact-stabilization process provides separate tanks for initial micro-organism waste
contact and stabilization. The micro-organism-waste-contact part of the process generally requires
15-30 minutes. Following the tank in which initial contact takes place, a clarifier is used to settle
out the micro-organisms and the organic material entrapped with them. The settled sludge is then
pumped to a second aerated basin where the time and air required to stabilize the entrapped organic
material is furnished. The overflow from the clarifier is then chlorinated and discharged directly
to a receiving stream.
The contact-stabilization process allows a substantial savings in basin size over the conventional
system. The short detention time in the first basin and the smaller volumes of sludge recycled to the
second basin make this savings possible. There are not many designed true contact-stabilization
systems, and none for meat packing wastes.
23
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Completely Mixed Activated Sludge
By providing enough mixing in the aeration tank to mix completely the incoming wastewater
with the contents of the tank, it is theoretically possible to obtain any degree of treatment desired.
The rapid mixing produces a homogeneous mixture of wastewater and activated sludge within the
aeration basin. Any slugs of incoming waste are mixed quickly and distributed evenly throughout
the basin, reducing the chance of system upset commonly associated with conventional systems.
Extended Aeration
A completely mixed, activated-sludge system designed for long detention time (24 hours or
more) is known as an extended-aeration system. Extended-aeration systems operate at the lowest
BOD loadings of any activated-sludge system. Due to the smaller amounts of food available to the
organisms, nearly complete oxidation occurs for micro-organisms and BOD removals are high.
Removals in excess of 95 percent are not uncommon.
Provision must still be made, however, for wasting sludge, as solids tend to accumulate within
the system. Generally, provision is also made for 50-100 percent sludge recycle to the aeration basin
from the final clarifier.
Advantages of the extended-aeration system include ability to handle shock loads, low capital
investment due to elimination of primary clarifiers and sludge digestion equipment, as well as the
capability to produce a nitrified effluent.
Nitrification in Extended Aeration
Long detention times and aerobic conditions found in extended-aeration systems provide an
ideal atmosphere for the process of nitrification. Under aerobic conditions, ammonia is converted
to nitrites and nitrates by specific groups of nitrifying bacteria. A sludge detention time of 8-10
days is required for the nitrifying organisms to establish themselves in sufficient numbers to accom-
plish any significant degree of nitrification. Usually, extended-aeration systems designed to accom-
plish nitrification are designed for sludge detention times in excess of 10 days. Although liquid
detention times in the system are generally approximately 24 hours, the sludge age may be con-
trolled by regulating the amounts of sludge recycled and wasted each day.
Oxygen (for the oxidation of ammonia) must be supplied in excess of that required for BOD
reduction. About 4.33 pounds of oxygen are required to convert 1 pound of ammonia nitrogen
to nitrates. This need results in a substantial increase in air requirements over those required for
BOD reduction alone, necessitating the installation of larger, more expensive aeration equipment.
Extended-aeration systems that follow anaerobic lagoons are capable of producing an effluent
low in BOD and ammonia nitrogen. Anaerobic lagoons are capable of BOD reductions in excess of
80 percent; however, under anaerobic conditions the protein in the packing-plant wastes are
decomposed, resulting in the conversion of most nitrogen forms present to ammonia nitrogen and
some nitrogen gas. The nitrogen gas escapes to the surrounding atmosphere, but the ammonia
nitrogen remains in the anaerobic pond effluent, creating an additional oxygen demand if dis-
charged to a receiving stream. Further, ammonia nitrogen is toxic to fish at low concentration.
The use of an extended-aeration system following anaerobic lagoons provides the time and air
required to reduce the remaining BOD and convert the ammonia nitrogen to nitrates. Following
final sedimentation and chlorination, the effluent may be discharged to a receiving stream with a
minimum of impact.
24
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It should be noted that although the nitrogen in the plant effluent does not create a significant
oxygen demand upon the receiving stream, it does remain a nutrient source, enhancing the possibility
of undesirable aquatic plant growth and algae blooms.
Activated-Sludge Treatment for Meat-Processing Wastes
All of the previously mentioned activated-sludge systems may be used to treat wastes character-
istic of the meat packing industry. The particular system chosen will depend on the degree of treat-
ment desired and the existing facilities available for use.
The conventional, tapered-air, step-aeration, contact-stabilization, completely mixed, and
extended-aeration systems will all produce an effluent capable of meeting effluent standards for BOD
reduction. In many cases the particular system chosen will depend to a large extent upon the
characteristics of the effluent from existing treatment facilities.
For example, many meat processors use anaerobic lagoons for reduction of BOD. The effluent
from these lagoons is usually still quite high in BOD and contains large amounts of ammonia nitrogen.
Extended aeration following anaerobic lagoons, as mentioned earlier, performs quite well in reduction
of the remaining BOD and nitrification of ammonia nitrogen. This treatment system functions well,
meeting both BOD and ammonia nitrogen effluent standards.
Some of the loading and operational parameters for the activated-sludge processes described
earlier are presented in table IV-2. BOD loadings to aeration tanks are calculated using the influent
wastewater BOD only. Loadings are expressed as pounds applied per day per 1,000 ft3 of aeration
tank volume and pounds of BOD per day per pound mixed-liquor suspended solids (MLSS) in the
aeration basin. Aeration periods, expressed in hours, are calculated using the daily average flow
without regard to return sludge flow. The return sludge flow usually is expressed as a percentage of
the daily average flow.
TRICKLING FILTERS
Trickling filters commonly are used for biological wastewater treatment. With this system,
wastewater that has undergone primary settling is sprayed over beds of rock or other media to
achieve contact between micro-organisms present on the surface of the media and organic material
in the wastewater.
A trickling filter is composed of three main components.
• The rotary distribution arms (fig. IV-8)
• The media (fig. IV-8)
• An underdrain system
Where ample head is available, rotary distribution arms are turned by the reaction of water
leaving nozzles in the arm. Distribution arms are used to distribute uniformly the wastewater flow
over the filter media. Where sufficient head is not available, water must be pumped to the
distributor.
25
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Table IM-2.—General loading and operational parameters for activated-sludge processes
Process
High rate (complete mixing)
Step aeration
Conventional (tapered aeration) ....
Contact stabilization
Extended aeration
BODI
Pounds BOD per
1,000ft3
100 up
30-50
30-40
30-50
10-30
3 ad ing
Pounds BOD per
pound MLSS
0.5-1.0
0.2-0.5
0.2-0.5
0.2-0.5
0.05-0.2
Aeration
period,
hours
2.5-3.5
5.0-7.0
6.0-7.5
6.0-9.0
20-30
Average return
sludge rates,
percent
100
50
30
100
100
BOD
efficiency,
percent
85-90
90-95
95
85-90
85-90
SOURCE: Water Supply and Pollution Control, p. 507, Clark, Viessman, and Hammer, International Textbook Co., 1971.
'^^^^g^r.V'1^ •'''" 1;"-
' "' Ik
•fr %
Figure IV-8. Trickling-filter arms and media. Farmland Foods.
The filter media provides both a surface for the biological growth as well as voids for move-
ment of air and water through the filter bed.
Because of its low cost, durability, and availability, stone or crushed rock has been the most
popular filter media in the past. New materials have been developed recently and are on the market.
They include various plastic media and redwood slats. Advantages of the newer media include lower
weight, chemical resistance, and a high specific surface area with a large volume of void spaces. Thus
the synthetic media will require significantly less space to accomplish the same degree of treatment.
26
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The underdrain system provides the means to carry away the filter effluent, allows circulation
of air through the filter bed, and provides structural support for the filter media.
Filters using lightweight plastic media are able to make use of much deeper beds (up to 21.5
feet) than those using crushed rock.
The high-rate filter and the roughing filter are the most common trickling-filter systems
presently used. Flow diagrams for the high-rate- and roughing-filter systems are shown in figure IV-9.
BOD loadings to trickling-filter systems generally are expressed either as pounds of BOD per
1,000 ft3 of filter media, or as pounds per acre-foot of media. Hydraulic loadings are expressed as
million gallons per acre per day of filter area, or as gallons per minute per square foot of filter area.
The hydraulic loading is computed using both the raw wastewater flow plus the recirculated flow.
The high-rate trickling filter is capable of achieving BOD reductions as high as 90 percent with
proper recycle and loading rates. Removals in the roughing filter are considerably less than those in
the high-rate system.
The major use of trickling filters in the meat-processing industry involves their use as roughing
filters. Roughing-filter systems operate at hydraulic and BOD loadings much higher than those of
conventional trickling-filter systems. Their major function is to smooth out influent shock loads and
provide some initial reduction of BOD. In most cases roughing filters are used prior to some type
of the activated-sludge system.
ROTATING BIOLOGICAL DISKS
The use of rotating biological disks (see fig. IV-10) is a new approach to the treatment of meat-
processing wastes. The disks were first developed in Europe in 1955 for the treatment of domestic
wastes. Today there are approximately 1,000 domestic installations located primarily in West
Germany, France, and Switzerland. Development work on the rotating biological disks in the United
PRIMARY
SEDIMENTATION
PRIMARY
SEDIMENTATION
FILTER
T r~?
HIGH RATE
FILTER
ry
ROUGHING
FINAL
SEDIMENTATION
^ RECYCLE
V
FILTER
A TO FOLLOWING
I TREATMENT
FILTER
SYSTEMS'
Figure IV-9. Flow diagram, high-rate and roughing trickling filters.
27
-------
Figure IV-10. Rotating biological disks, Iowa Beef Processors, Inc., Dakota City.
States began in 1965. Use of the disks in the treatment of meat-processing wastes is recent, and, to
date, no operational data are available except on a pilot-plant scale. A large treatment facility for
the Iowa Beef Processors plant at Dakota City, Nebr., is currently under construction and should be
in operation later this year.
The rotating-biological-disks system consists of large-diameter, lightweight plastic or high-
density Styrofoam disks, mounted on a horizontal shaft and placed in a semicircular tank containing
wastewater. Organisms present naturally in the wastewater adhere to the rotating surfaces and
begin to multiply. The disks rotate through the wastewater, which adheres to them. The wastewater
then trickles down the disks, absorbing oxygen. The aerobic organisms present in the wastewater
then use the oxygen to reduce the organic matter in the wastewater. As the disks continue to rotate
through the wastewater, the organic material is reduced further. The disks support a growth of
organisms, provide aeration of wastewater, and also provide contact of organisms with the wastewater.
Excess growths of organisms slough off the disks. This activity minimizes clogging problems and
maintains a nearly constant growth of organisms on the disks. The mixing action of the disks in the
wastewater prevents the solids that have sloughed off from settling in the tank. These solids are
removed in a final clarifier following the disks.
BOD removal and oxidation of ammonia nitrogen have been found to be directly proportional
to the hydraulic loading on the disk units. At a specific hydraulic loading, a given percentage of
BOD generally is removed even with fluctuation of the influent BOD. As a result, the principal
design criterion is hydraulic loading.
Wastewater temperature will affect rotating-biological-disk efficiency, but this effect is negligible
for normally encountered ranges of temperature. Wastewater temperatures in the range of 60° to
80° F have little effect on disk-treatment efficiencies. Waste temperatures from packing plants will
28
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average generally from 80° to 95° F; thus, the treatment efficiency will be higher than normally
experienced.
The arrangement of biological media (organisms) in a series of stages has been shown to
enhance the overall treatment of a wastewater, because the organisms that develop on each succes-
sive stage (disk) are adapted to treat the characteristics of the wastewater in each stage. Generally,
the organisms present in the first stages remove the organic (carbonaceous) material present in the
wastewater, while the last-stage organisms are adapted to converting ammonia nitrogen to nitrate
nitrogen (nitrification). Nitrogen in the ammonia form is toxic to aquatic life.
The rotating biological disks should be enclosed to protect the organisms from cold tempera-
tures and to help control odor emissions. As discussed earlier, waste-treatment efficiencies are
reduced considerably when temperatures fall below 55°-60° F. The enclosure helps to prevent
winter weather from adversely affecting the treatment system. The enclosure will help also to
control odor problems that may occur, by confining the odors in the building. Adequate ventilation
is imperative, however, particularly if the waste flow is anaerobic when it enters the system. An odor
control system may be required.
The type of enclosure generally used for a rotating-biological-disk system is a timber or concrete
building with a poured-concrete floor. Steel construction is not generally suitable since the air
within the rotating-biological-disk building has a high degree of humidity.
A simplified, typical flow schematic illustrating the treatment of a meat packing waste using
rotating biological disks is shown in figure IV-11. The raw wastewater flows into anaerobic lagoons
or into a pretreatment facility, where suspended solids and BOD are removed and where flows are
equalized. The partially treated flow then goes to the rotating biological disks, where the organic
material is converted to a biological floe that can be settled in the final clarifiers. The wastewater is
then disinfected by chlorination before discharge to the receiving stream.
Rotating biological disks also can be used in completely aerobic systems. The disks must be
preceded by adequate grease removal. The number of stages of disks required will depend upon the
desired degree of treatment. The system will also include a final clarifier and chlorination. A system
of this type currently is treating wastes at Kralis Poultry in Olney, 111. The effluent is discharged to
the municipal sewer system. With four stages, BOD and suspended solids less than 200 mg/1 have
been achieved.
FINAL
CLARIFIERS
ANAEROBIC
LAGOONS
OR PRE-
TREATMENT
ROTATING
BIOLOGICAL
DISCS
INFLUENT
Figure IV-11. Typical flow schematic, rotating biological disks.
29
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IRRIGATION METHODS FOR THE MEAT PACKING INDUSTRY
As water quality standards become more stringent, increasingly elaborate and complex treat-
ment systems become necessary. These tertiary treatment systems will have a high first cost as well
as high annual operation and maintenance costs, all of which must be borne by the meat packer.
One possible alternative is the disposal of treated wastewater by application to the soil. Where
sufficient land area is available, this method may be less expensive in first cost, as well as in operation
and maintenance costs, when compared to a highly sophisticated tertiary treatment facility.
Application of wastewater on the soil can be a natural and efficient method of waste disposal.
During movement into and through the soil, contaminants are removed by chemical, biological, and
physical action. Generally, soil disposal systems are classified according to the mode of application
of wastewater. In the physical sense, they differ with respect to the volume of water applied and
the pathway taken by the liquid through the soil. There are three basic methods of irrigation that
can be used for ultimate disposal of wastewater: spray irrigation, overland runoff, and rapid
infiltration.
Spray Irrigation
Spray irrigation is defined as the controlled spraying of wastewater onto the land, at a rate
measured in inches of wastewater per week, with the flow path being infiltration and percolation
within the boundaries of the disposal site with no surface runoff. Natural precipitation is a factor,
because wastewater applications must be suspended or greatly reduced when the ground is very wet
from heavy or prolonged rain or snow. Because spray irrigation is limited generally to the plant-
growing months, adequate storage ponds must be constructed as part of the system.
The major limiting factor in spray irrigation is the maintenance of infiltration capacity, which
is reduced due to clogging of the soil by solids present in the wastewater. The most common method
of restoring the infiltration capacity of a soil involves the intermittent application of wastewater with
intervening rest periods. If wastewater were to be applied continuously to the soil, an equilibrium
infiltration rate eventually would be established—a rate generally too small to be acceptable.
Another important factor in spray irrigation is the necessity of maintaining aerobic conditions
in the soil to insure proper treatment of the wastewater. Consequently, application rates should be
significantly less than infiltration capacities if unsaturated soil conditions (i.e., aerobic conditions)
are to exist in the infiltration surface.
Ground water characteristics must be studied thoroughly before spray irrigation is commenced
in order to preclude the possibility of ground water contamination. The soil mantle between the
ground surface and the water table must be of sufficient depth to insure treatment of the wastewater
before it reaches the ground water. Caution must be exercised where geologic conditions include
fracture zones (e.g., limestone formations) for rapid water movement with little filtration may result
in contamination. Minimum depths from the ground surface to the ground water table may vary
from 10 feet to 15 feet depending on the infiltration rate of the particular soil.
Spray application rates usually are expressed in terms of inches of liquid depth per unit of time.
Net weekly applications may range from 0.2 inch to 6 inches, but the most common application
rate is 2 inches. Application rates and weekly application amounts generally are selected in terms
of the capacity of the vegetation to take up nutrients. Usually this method results in application
rates being less than infiltration rates.
30
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Many different crops have been used successfully in land disposal operations, including wheat,
corn, alfalfa, clover, and Sudan grasses. Corn and some of the grasses grown as hay crops have
significant nutrient uptake capabilities.
Spray irrigation can be practiced on land that is either flat or gently rolling. Land areas
characterized by steep slopes will become eroded before infiltration can take place.
Spray equipment will vary, depending on the site topography and crop. (Conventional
aluminum irrigation pipe commonly is used.) For large, permanent facilities, the pipe network
can be buried, with only risers and spray nozzles appearing above the ground surface. At sites with
flat or rolling terrain, center-pivot irrigation systems can be used successfully. Self-propelled
traveling sprinkler systems (figs. IV-12 and IV-13) are another common type of equipment.
Overland Runoff
Overland runoff is defined as the controlled discharge (of wastewater onto the land) by spraying
or other means, at a rate measured in inches per week, with the flow path being downslope sheet
flow. This method of wastewater application relies on the treatment of the wastewater during its
passage over the ground as a thin liquid layer, due to contact with the soil and plant roots. Overland
runoff is best suited to sloping sites with impermeable subsoils.
Natural precipitation is a factor in overland runoff, requiring either the suspension of wastewater
applications or substantial reduction in rates during periods of sustained rain or snowfall.
Figure IV-12. Traveling sprinkler system.
31
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Figure IV-13. Detail, traveling sprinkler system.
One of the major design considerations in designing an overland runoff system is achieving and
maintaining proper overland flow. Flow that is too slow can result in ponding and anaerobic condi-
tions; too rapid flow will result in inadequate contact time between the waste water and the soil and
vegetation. The site must be steep enough to maintain desired flow without causing erosion. Slopes
for overland flow may vary between 2 percent and 6 percent. Unbroken slope lengths should not
exceed 300 feet, while application rates average 2 inches per week.
The treated wastewater is intercepted in collection ditches at the toe of the slope, and then
discharged directly to a receiving stream. If the wastewater is not yet adequately treated, it may be
discharged across a second slope before ultimate discharge to the stream or ditch.
Fixed spray nozzles are usually used in applying wastewater to the land for overland runoff.
The pipe network may be buried with only risers and spray nozzles appearing above the ground
surface.
Plant species currently used in overland runoff installations consist of grasses grown for hay
cropping, such as Kentucky blue, Bermuda, red top, and fescue.
Rapid Infiltration
Rapid infiltration is similar to spray irrigation in that the wastewater is intended to infiltrate
the soil and become treated during percolation. With a rapid-infiltration system, however, the
application rates are substantially higher and the wastewater is applied by spreading or flooding
32
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rather than by spraying. Precipitation is not a significant factor, because the liquid volume of the
spreading basins will be relatively unaffected by rainfall.
The limiting factor in rapid infiltration is the maintenance of infiltration capacity. Surface
clogging can be controlled by the intermittent application of wastewater, with intervening rest
periods.
The depth of the ground water table is of major concern in rapid infiltration, just as it is in
spray irrigation, owing to the possibility of ground water contamination. Minimum distances
between the ground surface and water table may range between 10 and 15 feet, depending on the
type of soil.
Application rates will vary considerably, ranging from 6 inches to 2 feet per day.
Irrigation Design Report
Before the time an irrigation system is placed in operation, most State regulatory agencies will
require an irrigation design report. This report usually must include maps and diagrams of the area
affected by the irrigation system, as well as any additional pertinent material about the location,
geology, topography, hydrology, soils, areas for future expansion, and adjacent land use. The system
must be designed to prevent surface runoff from leaving and entering the site, and must be adequately
fenced.
33
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THIS PAGE INTENTIONALLY
BLANK
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Chapter V
OPERATION AND MAINTENANCE OF WASTE-TREATMENT PLANTS
The construction of a wastewater-treatment facility is only the first step in the process of
achieving successful waste treatment. The second, equally important step is the proper operation
and maintenance of the physical plant to insure the treatment that the system was designed to
achieve. Responsibility for this program should be in the hands of well-trained and conscientious
personnel.
Industries using complicated treatment facilities and plants using relatively simple treatment
systems both require someone in charge who has a thorough knowledge of his job. The plant
operator is often called upon to make adjustments or modifications in the treatment units to
obtain maximum treatment efficiency. The equipment must receive proper care if the treatment
system is to provide the degree of treatment designed into the system.
A good program of waste flow sampling can help substantially in obtaining the optimum
degree of treatment. In addition to providing the required data for regulatory agencies, a complete
record of treatment factors may help the operator cope with present inconsistencies and future
expansion in the waste treatment system. Familiarity with the physical appearance of the raw
influent and of the well-treated or undertreated effluent flow will provide an indication to the
operator of an upset or change that will require more detailed and careful sampling. A reliable
and workable arrangement must be made for the analytical work that is required, whether this
work is performed by company personnel or by an outside agency.
The operational problems to be encountered will depend on the waste characteristics, type
of treatment, climate, and design. All manufacturers' data should be read, understood, and kept
as a permanent record, along with all shop drawings. A detailed manual relating to proper opera-
tion of treatment plants, such as one published by the Water Pollution Control Federation, should
be readily available as a reference for all employees associated with the waste-treatment facilities.
Such manuals contain information on the causes and cures of many operational difficulties en-
countered in usual types of treatment. Operational practices for anaerobic and aerobic lagoons may
be found in numerous textbooks or published articles in wastewater journals. Further, an operation
and maintenance manual dealing with the specific waste-treatment system should be provided to
the industry by the engineer who designs the facility.
In addition to proper operation, the importance of maintaining the physical structures cannot
be underestimated. A system of routine inspection and maintenance should be established, based
on the nature and needs of the equipment. All literature from the manufacturer relating to equip-
ment upkeep should be filed for future reference after being studied by the operations staff. A
supply of spare parts, as recommended by the manufacturer, should be kept on hand at all times.
If possible, daily attention should be given to the operation and maintenance of the system.
Simple systems may require little day-to-day care, but they should be checked regularly. Care
of the treatment site is also important. Mowing should not be neglected, fences and gates should
be kept in good repair, and utilities should be maintained.
35
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There follows a schedule listing some of the many types of maintenance required on various
segments of the complete system. This schedule should serve only to provide a base upon which
each individual plant operator may build his own waste-treatment operation and maintenance
program.
Pumping Stations
1. Hose down wet well to control grease accumulations.
2. Check packing glands for correct tightness (centrifugal pumps).
3. Adjust V-belt drive as necessary.
4. Lubricate pumps according to manufacturers' recommendations, using high-grade lubricants.
5. Check bearings for overheating after starting pump.
6. Inspect pump and bearings on shutdown so that necessary maintenance can be performed
during shutdown period.
7. Inspect water-level controls in wet well to insure proper operation.
8. Check electric motor pump drives periodically.
9. Alternate pumps weekly if automatic alternation is not provided.
Screening Facilities
1. Check daily to determine if screens require cleaning.
2. Rake screens and dispose of material by burying or other suitable means.
Sedimentation Tanks (Clarifiers)
1. Check tanks and equipment several times daily for proper operation.
2. On a regular schedule, clean inlet baffles, effluent weirs, and scum removal mechanisms.
3. Hose down all spills.
4. Keep lubrication records for all equipment, and use high-grade lubricants.
5. Drain tanks annually and inspect all systems for wear and corrosion. Replace badly worn
equipment and adjust all chains.
Trickling Filters
1. Inspect rotating-arm nozzles daily for clogging. Clean as required.
2. Check bearings and lubricate in accordance with manufacturers' recommendations.
36
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3. Adjust guy lines to account for seasonal temperature variations, thus allowing arms to
remain horizontal.
4. Check filter surface daily for contaminants, such as leaves or debris.
5. Periodically inspect underdrain system for clogging.
6. Follow recommended courses of action if trouble develops, such as ponding, filter flies,
odor, and icing.
Chlorination Facilities
1. Check daily for proper functioning of all systems.
2. Check for leaks every 8 hours.
3. Check safety equipment monthly.
4. Check feed rates every 8 hours.
Activated-Sludge Systems
1. Check air compressors for lubrication and overheating.
2. Check air filters daily for cleanliness. Clean monthly.
3. Use rotation schedule for compressors to insure even wear.
4. Check compressor for satisfactory performance.
5. Check air flow in tanks every 8 hours.
6. Check all aeration tanks annually and repair or replace worn equipment.
Sampling
1. Check raw flow rate weekly, preferably daily.
2. Perform periodic settleable solids tests on influent and effluent flow.
3. Perform daily DO, BOD, suspended solids, and settleable solids tests on activated-sludge
systems to insure proper operation.
4. Run BOD, suspended solids, and DO tests daily or biweekly at trickling-filter plants, but
not less than two times a week.
5. Run tests for nitrates, ammonia nitrogen, and organic nitrogen, and possibly for phosphates
on samples collected preceding and following treatment at regular intervals.
6. Perform daily tests for settleable solids, suspended solids, and total and volatile solids on
samples from sedimentation units. Check sludge for total and volatile solids to provide information
required for proper operation of sludge recirculation and drawoff systems.
37
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7. Perform, at regular intervals (for both influent and effluent), grease determination on all
grease removal systems.
8. Perform all tests on plant effluents required by regulatory agencies.
General
1. Mow grass on ground dikes.
2. Keep in good repair all external construction, such as buildings and sheds.
3. Check for leaks in valves and other appurtenances.
4. Check operability of all valves and gates.
38
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Chapter VI
CASE HISTORIES
AMERICAN BEEF PACKERS, INC.
The American Beef Packers, Inc., plant at Council Bluffs, Iowa, was constructed in 1969.
The plant consists of beef-slaughtering and -processing facilities in a main plant, with hide-processing
facilities located in an adjacent building. Waste-treatment facilities included with the plant construc-
tion consisted of an air flotation tank to remove grease from the slaughtering-processing waste
stream, followed by an aerated lagoon. Effluents from the flotation tank and the hide-processing
building were discharged separately to the aerated lagoon before disposal in the city sewer system.
Four 50-hp, slow-speed, pedestal-supported mechanical aerators, located at the south end of the
aerated basin, were used to supply oxygen for BOD reduction.
Anaerobic odors emanating from the aerated basin owing to an insufficient amount of aeration,
coupled with recently increased sewer surcharge fees established by the city of Council Bluffs for
discharge of the plant effluent into the municipal sewer system, made upgrading of the existing
treatment facilities necessary and economically advantageous. Modifications to the existing facilities
were investigated that would stop the odor nuisance caused by anaerobic conditions in the aerated
basin and increase overall BOD removals to comply with standards required for discharge to the city
sewer without surcharge.
The system designed to upgrade the existing facilities was an extended-aeration system based
on the following design data:
• BOD loading = 18,000 Ib/day
• Design flow =1.5 mgd
At a design flow of 1.5 mgd, the existing basin provides a detention time of 3.5 days, which is
more than adequate for the extended-aeration system. The air supplied to the basin was considered
insufficient both for the necessary mixing and for BOD reductions, as evidenced by the anaerobic
conditions existing at the northern end of the basin. Consequently, eight 40-hp, high-speed floating
aerators were added to the existing aeration basin to provide the additional air required. As an
integral part of the extended-aeration system, a 55-foot-diameter, concrete clarifier (fig. VI-1) was
constructed, with provisions for sludge return in an amount equal to 100 percent of the design flow.
Effluent from the clarifier is discharged to the existing city sewer system. The schematic flow
diagram for the plant is shown in figure VI-2.
Grease skimming and solids screening are provided for the hide-processing effluent (brine
curing) before discharge to the aeration basin. (See figs. VI-3 to VI-5.)
The eight 40-hp aerators were installed in the aerated basin before completion of the clarifier
in order to correct the prevailing anaerobic conditions. The aeration equipment was furnished at a
cost of $35,000, and was installed by American Beef Packers. The new 55-foot-diameter clarifier,
39
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Figure VI-1. Final clarifier, American Beef Packers, Inc.
AEROBIC LAGOON EFFLUENT
NEW 55' DIA
CLARIFIER
PLANT EFFLUENT
TO EXISTING CITY
SEWER
TO AERATED
LAGOON
EXISTING FLOTATION
TANK
SLAUGHTERING -
PROCESSING WASTE
FLOW
Figure VI-2. Flow schematic, American Beef Packers, Inc.
40
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Figure VI-3. Grease flotation tank, American Beef Packers, Inc.
Figure VI-4. Hide-settling tank, American Beef Packers, Inc.
41
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Figure VI-5. Solids-screening facility and hide-processing settling tank,
American Beef Packers, Inc.
including the recirculation system and all piping, cost $70,000 to construct, with an additional
$20,000 for equipment. The system is operating as an extended-aeration system, providing a high
degree of secondary treatment. Recent sampling data from the effluent of the final clarifier resulted
in a BOD of 100 mg/1, suspended solids concentration of 100 mg/1, and a grease concentration of
90 mg/1. The site plan for the facility is shown in figure VI-6.
IOWA BEEF PROCESSORS, INC., DENISON
Iowa Beef Processors, Inc., recognized in 1966 the need for secondary waste treatment for
their beef slaughtering plant at Denison, Iowa. An anaerobic-aerobic lagoon system was determined
to be the best type of treatment facility, and was designed using the following factors:
• BOD loading = 9,600 Ib/day
• Design flow = 720,000 gal/day -
• Anaerobic lagoon loading = 15 Ib BOD per 1,000 ft3
• Depth of anaerobic lagoon = 15 feet
• Assumed efficiency = 65 percent
• First-stage aerobic lagoon loading =150 pounds BOD per acre
• Second-stage aerobic lagoon loading = 50 pounds BOD per acre
42
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Figure VI-7 shows the schematic layout and flow diagram for the system. Figure VI-8 presents
the layout photographically. Plant waste undergoes pretreatment in an air flotation unit, while pen
wastes flow through a settling basin before discharge to the lift station. The combined pen and
plant wastes flow through a mechanically cleaned bar screen and measuring flume, and are then
pumped to the anaerobic lagoons. These two lagoons are operated in parallel with the effluent
discharged to two first-stage aerobic ponds, also in parallel. The effluent from the two cells receives
further treatment in a second-stage aerobic pond before discharge into the Boyer River.
Sampling data obtained by the State of Iowa Hygienic Laboratory indicate that the lagoon
system has performed well since its completion in November 1968. BOD removal efficiencies of
over 80 percent have been achieved consistently in the anaerobic lagoons, and the overall efficiency
of the system is approximately 98 percent.
The approximate 1967 cost of construction for the facility was $110,000, with much of the
labor performed by Iowa Beef Processors construction personnel.
With an operating anaerobic lagoon treatment efficiency of 80 percent rather than the assumed
design value of 65 percent, the actual loading to the first-stage aerobic pond is approximately 85
pounds of BOD per acre, and the final stage is approximately 30 pounds of BOD per acre. The site
plan for the facility is shown in figure VI-9.
FARMLAND FOODS
The wastewater-treatment system serving the hog-processing plant owned by Farmland Foods,
Denison, Iowa, was designed to treat the varied waste flows from the killing floor,, holding pens,
blood recovery system, and rendering and processing operations, as well as domestic sewers.
The plant kills 5,000 hogs per day, of which 40 percent usually are kept for further processing
operations and the rest are shipped. The processing operations include cutting and processing into
hams, bacon, and picnics. Rendering operations are performed on fat and bones, and there is a
blood recovery system for the kill floor. The major consideration in designing the waste-treatment
facility was the small amount of available land.
Construction on the project was initiated in April 1969. The facility now has been in operation
for approximately 2Vi years.
The raw waste criteria employed in the design of this treatment system are as follows:8
• BOD loading = 21,500 Ib/day
• Average flow = 850,000 gal/day
• Maximum daily flow = 1,000,000 gal/day
• Maximum hourly flow = 1,500,000 gal/day
The flow diagram for the treatment facilities is shown in figure VI-10. The wastes from the
kill floor are pumped to an air flotation unit for separation of grease, which is then returned for
aD. Baker and T. White, "Treatment of Meat Packing Waste Using PVC Trickling Filters," paper presented
at National Symposium on Food Processing, Denver, Colo., Mar. 23-26, 1971.
43
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Figure VI-6. Waste-pretreatment facilities site plan, American Beef Packers, Inc. (Shaded areas indicate overlap.)
44
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HYDRAULIC PROFILE
SCALED/IB"'i-o"
ELEVATION
SECTION
BAR SCREEN DETAIL
SCALE:|H«|'-0"
Figure VI-6. Waste-pretreatment facilities site plan, American Beef Packers, \r\c.-Concluded
45
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Figure VI-7. Flow schematic, Iowa Beef Processors,
Inc., Denison.
Figure VI-8. Meat-processing plant and lagoon layout, Iowa Beef Processors, Inc., Denison.
46
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rendering. The effluent from the flotation unit is combined with the raw waste from the pens,
scald tank, and domestic lines, and is sent to two parallel anaerobic lagoons. The lagoons provide
biological treatment and also serve as flow-equalizing basins.
After anaerobic treatment, the waste flow is preaerated to satisfy immediate oxygen demand
in preparation for discharge to the plastic media trickling filters. These filters normally are used in
series, with provisions for parallel operation. The filter effluent is then clarified and disinfected in
a chlorine contact basin before discharge to the Boyer River. Sludge is wasted back to the anaerobic
lagoons.
The air flotation unit functions primarily to remove grease, and was designed with the following
dimensions and performance criteria:
• Hydraulic loading = 1,500 gal/min
• BOD removal = 40 percent
• Grease removal =85 percent
• Diameter = 22.5 feet
• Depth = 12 feet
The anaerobic lagoons were designed to achieve a significant reduction in BOD and to prevent
shock loads from upsetting the filters. The basis of their design is as follows:
• BOD loading = 12,900 Ib/day
• Design loading = 15 pounds BOD per 1,000 ft3
• Depth = 14 feet
• Surface area = 1.97 acres
• BOD removal = 80 percent
The preaeration basin (fig. VI-11) serves to help reduce odors that may emanate from the
anaerobic effluent. Such odors would create serious problems owing to the close proximity of a
residential area. The design engineers also hoped to begin converting the effluent from the anaer-
obic lagoons to an aerobic state before sending it to the filters. With these factors in mind, the unit
was designed with 30-minute detention time and an applied air flow of 100 ft3/min.
The trickling filters have shown the best results when they have been operated in series. The
synthetic filter media is polyvinyl chloride (PVC) manufactured by B. F. Goodrich Co. This type
of media ™ay be loaded at higher rates, is lighter in weight, and is more uniform than standard
rock media. The media is formed in 2-foot by 4-foot by 2-foot sections that are stacked in layers
of 11 cells, resulting in a total depth of 22 feet. Design data for the filters are as follows:
• BOD loading, first stage = 101 pounds per 1,000 ft3
• BOD loading, second stage = 31 pounds per 1,000 ft3
• Hydraulic loading =0.5 gal/min/ft2
47
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ELLCTBICAL Lmt. DIAGRAM
Figure VI-9. Waste-treatment facilities site plan, Iowa Beef Processors, Inc., Denison.
(Shaded areas indicate overlap.)
48
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ivERSIOU STRUCTURE
AT STOCK._PEHS
Figure VI-9. Waste-treatment facilities site plan, Iowa Beef Processors, Inc., Denison.—Concluded
49
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WASTES FROM
KILL FLOOR
OAIR R-O1
TANK
Figure VI-10. Flow schematic. Farmland Foods.
Figure VI-11. Preaeration basin, trickling filters, and control building. Farmland Foods.
50
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• BOD removal = 91 percent
• Diameter = 39 feet
• Medium depth = 22 feet
The final clarifiers (fig. VI-12) are considered part of the trickling-filter system, and are designed
to provide adequate settling times for the filter effluent. Two 26-foot-diameter clarifiers are used at
Farmland Foods, each with a surface overflow rate of 800 gal/day/ft2.
The chlorine contact chamber (fig. VI-13) was designed for a contact time of 49 minutes and a
chlorine dosage rate of 10 mg/1.
Figure VI-14 shows the treated effluent from Farmland Foods.
Table VI-1 shows the plant efficiencies, both for the total plant and unit by unit.
The operating expenses for the year 1970 are given below in table VI-2. The daily cost of
operation was approximately $304.
IOWA BEEF PROCESSORS, INC., DAKOTA CITY
The Dakota City, Nebr., plant of Iowa Beef Processors, Inc., lies just outside the Metropolitan
Sioux City, Iowa, area. The plant is bounded by Dakota City on the south, South Sioux City on the
north, the Missouri River on the east, and a populous suburban area on the west.
Figure VI-12. Final clarifier. Farmland Foods.
51
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Figure VI-13. Chlorine contact tank. Farmland Foods.
Figure VI-14. Treated effluent. Farmland Foods.
52
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Table VI-1.-Plant efficiencies, percent removal. Farmland Foods
Unit
Flotation
Anaerobic lagoons
Trickling filters
Chlorine . .
Total plant removal, excluding flotation . .
BOD
33
82
74
NA
97.4
COD
11
68
73
NA
91.5
Grease
62
78
69
NA
96.5
Suspended
solids
32
59
80
NA
93.5
Coliform
NA
NA
NA
99+
99+
SOURCE: D. Baker and T. White, "Treatment of Meat Packing Waste Using PVC Trickling Filters," paper presented at National
Symposium on Food Processing, Denver, Colo., Mar. 23-26,1971.
Table \l\-2.-Operatingexpenses, 1970
Item
Dollar cost
Salaries
Utilities
Maintenance
Capital cost debt retirement . .
Total ....
47,893
1,443
10,413
50,900
110648
The plant has the capacity to slaughter 2,400 head of cattle per day, to process 3,000 head per
day into institutional cuts, and to bone completely 900 animals per day. The average wastewater
flow rate is 3 mgd, and the raw waste load to the treatment facility is 33,600 pounds BOD per day
and 28,000 pounds suspended solids per day. The average temperature of the waste coming from
the combined slaughtering and processing operations ranges between 90° and 105° F. The high
strength of the wastes, combined with the high temperature, provided ideal design conditions for
anaerobic lagoons, which were chosen for the first stage of the new waste-treatment facility.
The concept of using rotating biological disks following anaerobic treatment had not been
tried before development of the Iowa Beef Dakota City project. All previous research and opera-
tional data had been in the area of domestic wastewater, and it was necessary to establish independ-
ent data for the design. As a result, a pilot test program, using the anaerobic effluent from one of
the company's existing waste-treatment facilities, was initiated to evaluate the rotating biological
disks. The pilot plant consisted of three stages of 4-foot rotating disks, each capable of delivering
1,750 gal/min, with 50 disks in each stage, followed by a small steel circular clarifier. Composite
samples were taken of the influent and effluent from each stage and of the effluent from the final
clarifier. Variations were made in speed of rotation of the disks as well as in rate of flow to the
units. As a result of the pilot study, design parameters were established for application in the full-
scale design.
The total waste-treatment facility, now nearing completion, consists of a lift station and force
main, anaerobic lagoons, rotating biological disks, final clarifiers, and chlorination facilities, as
shown in figure VI-15. Iowa Beef Processors, Inc., Dakota City, applied for and received a Federal
demonstration grant to assist in the construction of the project.
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tORCE MAIN I
FROM LIFT |
STATION [
RETURN SLUDGE
ANAEROBIC
LAGOON
(TYP)
\
ROTATING
BIOLOGICAL
DISC BUILDING
CHLORINE CONTACT
CHAMBER
OUTFALL TO
MISSOURI RIVfR
Figure VI-15. Waste-treatment facilities flow diagram,
Iowa Beef Processors, Inc., Dakota City.
The following design criteria were used in the design of the waste-treatment facilities:
• Design BOD = 33,600 Ib/day
• Design average flow = 3,000,000 gal/day
The lift station consists of three self-priming centrifugal pumps, each capable of delivering
1,750 gal/min. The pumps are driven by 40-hp motors, and deliver the wastewater to the anaerobic
lagoons through 6,200 feet of 18-inch force main.
The wastewater is discharged into four anaerobic lagoons operating in parallel. Each lagoon is
15 feet deep with a water surface area of 1.5 acres. The design BOD loading for these lagoons is
12 pounds per 1,000 ft3, and BOD removal averages approximately 85 percent.
The wastewater then flows to the rotating biological disks, which are housed in a timber pole
building (fig. VI-16). The design hydraulic loading on the disks is 4.8 gal/day/ft2, resulting in a total
required disk area of 625,000 ft2. This area is supplied by 24 shafts of 139 disks each. The disks
are 11 feet in diameter and have a surface area of 190 ft2 each. The anticipated BOD reduction
through the disk system is approximately 70 percent.
Following treatment in the RBS units, the wastewater is discharged to 55-foot-diameter
clarifiers (fig. VI-17), each designed for a design average flow of 1.5 mgd. Sludge from the clarifiers
is returned to the anaerobic lagoon.
54
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Figure VI-16. Rotating-biological-disk building, Iowa Beef Processors, Inc.,
Dakota City.
Figure VI-17. Final clarifier, Iowa Beef Processors, Inc., Dakota City.
55
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The wastewater then flows to the chlorine contact basin (fig. VI-18), which provides a chlorine
contact period of approximately 20 minutes at design average flow. The chlorine facilities include
a building and overhead crane for handling containers.
The effluent from the chlorine contact basin flows 800 feet to the Missouri River through an
18-inch outfall line.
The lift station, force main, and anaerobic lagoons have been in operation for approximately
ll/2 years. Operation of the entire facility, including the rotating biological disks, final clarifiers,
and chlorination system, in combination with the anaerobic lagoons, is expected within the next
several months. Since the total plant is not yet on line, operational data are not available regarding
treatment efficiencies. The anticipated overall BOD removal through the facility is approximately
90-95 percent. The site plan for the Dakota City plant appears in figure VI-19.
Total construction cost of the project including the lift station and force main is approximately
$814,000.
LYKES BROTHERS PACKING PLANT
The Lykes Brothers Packing Plant is located at Plant City Industrial Park in Florida, a State
that does not permit construction of anaerobic lagoons. Moreover, the site available for construction
of waste-treatment facilities was characterized by high ground water and sandy soil, features that
weigh heavily against any type of large lagoon. The treatment-system effluent was to be discharged
into a dry ditch, so a high degree of secondary treatment was required. After consideration of several
Figure VI-18. Chlorine contact tank, Iowa Beef Processors, Inc., Dakota City.
56
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different treatment schemes, the design engineers concluded that the extended-aeration modification
of the activated-sludge process would meet best the treatment needs of this typically high-strength
waste.
The packing plant slaughters up to 350 head of cattle per day, and includes beef dressing,
smoking, and sausage processing in its operation. An extensive program of water conservation and
waste flow pretreatment was undertaken before commencement of design to minimize the hydraulic
and organic loading on the treatment system. The final design criteria, based on 6 pounds of BOD5
and 900 gallons per head, was as follows:
• Total daily flow = 315,000 gal/day
• Total BOD5 = 2,100 Ib/day
The treatment system consists of a grease-skimming and sedimentation tank, two extended-
aeration tanks, final clarifier (fig. VI-20), polishing lagoon (fig. VI-21), aerobic digester, and sludge-
drying beds. The flow diagram is shown in figure VI-22.
The settling-grease-skimming basin is sized for 30 minutes' detention, with a small amount of
air added to aid in water and grease separation.
The extended-aeration tanks are operated in parallel and are sized on the basis of 20 pounds
per day of BOD removed per 1,000 ft3 of tank volume. The two tanks have a total volume of
105,000 ft3 and, based on the design flow, provide a retention period of 30 hours. Air is supplied
to the aeration tanks at the rate of 1,500 ft3/day/lb of applied BOD. Sludge is wasted periodically
to the aerobic digester.
The final settling tank is designed for a surface overflow rate of 800 gal/day/ft2. Settled sludge
is returned at a rate of 540 gal/min by an air lift pump to the head of the aeration tank or to the
aerobic digester.
Effluent from the settling tank flows into a 5-acre stabilization pond, which serves to provide
tertiary treatment before chlorination. A 30-minute detention period is provided by a small final
pond where chlorine is added at a fixed rate to produce an effluent having a 2-mg/l minimum
chlorine residual. 7
The aerobic digester has a volume of 37,200 ft3. Air is introduced into the digester at the rate
of 350 ft3/min to reduce further the well-oxidized solids developed in the extended-aeration
process. Periodically, a portion of the digested sludge is wasted to sludge-drying beds.
Recent sampling data obtained from personnel at Lykes Brothers Packing Plant are given in
table VI-3.
Total construction cost of the project in 1966 was approximately $250,000. Operational
and maintenance costs, as reported by plant personnel, are approximately $20,000 per year. This
figure includes labor, power, chemicals, lubrication, and miscellaneous items.
Information concerning the design of this facility was obtained from a paper published in
Journal of the Water Pollution Control Federation.^
bE. Willoughby and V. D. Patton, "Design of a Modern Meat Packing Waste Treatment Plant," J. Water
Pollut. Cont. Fed., Jan. 1968.
57
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TM y "» ""w**0 r^» *«*«*** ^
W «m. ^ tmnnMfI*.**«*4«*•«.*•». '/
SPLITTER STRUCTURE NO. 2 A IJ
SCALE Vi"'l'-0'
Figure VI-19. Waste-treatment facilities site plan, Iowa Beef Processors, Inc., Dakota City.
(Shaded areas indicate overlap.)
58
-------
,V?J
/ 'rife* W **-P TO M.H 4- UVUb 10 4VC.TIQM
A-jO CM»V€ KA.(MUt»«l
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V-'T** «T*OCTW«E"I
MANHOLE NO. 3 A < NOT IN CONTRACT - BUILT AS
SCALE 3/i".l'-O"
PART OF PHASE X)
SECTION
a'efjMR -_i
*'•" VoT ' 'o- «'tf V\
SPUTTER STRUCTURE NO. I A
SCALE S/»"« l'-O"
M.P nvr«\\
•-t-" r^ i i.:V<;g^3£
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^$^2^.-
JCCTJON.(~
SPLnTER STRUCTURE NO.3 (NOTJNCONTRACT-KJH.T
KAU 3/f- I'-O"
Figure VI-19. Waste-treatment facilities site plan, Iowa Beef Processors, Inc., Dakota City.-Concluded
59
-------
Figure VI-20. Final clarifier, Lykes Brothers Packing Plant.
Figure VI-21. Polishing lagoon, Lykes Brothers Packing Plant.
60
-------
GREASE HOLD
PLANT EFFLUFNT 1
BAR
GREASE
AIP
rt
SKIM
— i
— i
-o
-o
AIR
— *f
— ^
1
AIK
£
FACILITY ?,
STABILIZATION
POND
FRO'
PUN
f^ TV UPEN LJITCH
\^
rH SPRAY
«PS (•
a TURKLY
LF
>
\
LINE
HI
I"
\
\
/
• S
I
\
WET
WELL
PUMPS
J ^"
3]
zj
3
trl
J
If
-
FRUTH SPRAY
\-L/ LW
ETTLING\
TANK I
^ /
1 ' '
1
L Q
<
UJ
0
9
Ul
* x
I Ul
1
— 1
-1r'
<
%
0
i
UJ
H
X
III
SI Uf'GE
1
"~\
\
,
t
CE
1-
Ul
O
O
UJ
<
•— I
1
t
1
1
1
DRYING BEDS
LLK
CHLORINATION
Figure VI-22. Flow diagram, Lykes Brothers Packing Plant.
Table VI-3.—Wastewater analysis, Lykes Brothers Packing Plant,
6-month average values
Item
pH
BOD
Total solids ...
Suspended solids
Dissolved oxygen
Chlorides1
Raw
Effluent
from final
settling tank
Effluent from pond
milligrams per liter
6.9
1,574
5,507
396
0
1,787
7.4
89
3,621
180
.80
1,700
7.4
15.7
2,884
56
4.40
1,425
1 Approximately 1 ton of salt is used every 2 weeks for plant process.
Note.—Sampling data are based on an average water use of 240,000 gal/day.
61
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THIS PAGE INTENTIONALLY
BLANK
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Chapter VII
SURVEY OF EXISTING WASTE-TREATMENT FACILITIES
FOR THE MEAT-PROCESSING INDUSTRY
Questionnaires were sent to all 50 States in order to obtain data on the status of meat-
processing waste treatments in the United States. Many States did not have data available, and to
date 25 States have responded to the questionnaire. Several of the States indicated the existence
of few meat-processing facilities and, in these locations, existing plants were usually very small,
often not discharging a waste stream into a surface body of water. In such cases, septic tanks were
employed or other underground waste disposal schemes were practiced. Ponds that had only
seepage as effluent were also noted in some localities, notably in the Western United States where
the weather is arid.
Questionnaires returned from States where more and larger meat-processing operations were
located showed that more complex methods of treatment were employed. It is interesting to note,
however, that the regulatory agencies from these States felt that only half the treatment facilities
under their jurisdiction were effective. Many plants were operating well, but it was indicated
that upgrading was needed, and in some cases work was already in progress.
The types of treatment indicated as generally in use are anaerobic lagoons, anaerobic-aerobic
lagoons, anaerobic-aerated lagoons, various types of activated-sludge systems (mostly extended
aeration), aerobic lagoons or oxidation ponds, aerated lagoons, and trickling filters. An anaerobic
lagoon system followed by aerobic treatment was the most frequently listed type of treatment and
was reported as working well in achieving good BOD reduction. Values reported were in excess of
90 percent BOD removal, generally over 95 percent. Extended-aeration systems also showed high
BOD removals, in the range of 90 percent. There seemed to be a tendency to use extended aeration
in smaller plants with the lagoons being employed on large installations (i.e., those having greater
than 500,000 gal/day). Less frequently used systems were aerated lagoons or oxidation ponds.
Spray irrigation was used as a means of disposal, particularly in arid climates. Use of trickling
filters, based on the limited data, was not widespread. Such installations are in existence, of course,
and are capable of providing good treatment if properly loaded and operated.
Table VII-1 lists the types and number of waste-treatment facilities reported by the 26 States
responding to the questionnaire.
Table VII-1 is general in nature; in many cases the treatment scheme has been simplified for
this use. For example, if a system consisted of grease removal, primary screening, flow equaliza-
tion, extended aeration and chlorination, the overall system was classified as extended aeration.
Flow and performance data were taken from systems on which the information was provided,
some units being reported without data. It is interesting to note that one of the plants with no
treatment slaughtered 1,000 head per day and had a BOD of 2,250 mg/1. The report went on
to state, however, that a program is underway to provide treatment.
63
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Table VI1-1 .—Existing waste-treatment facilities for the meat-processing industry
Treatment
Anaerobic-aerobic lagoons
Anaerobic-aerated lagoons
Aerated lagoons-aerobic lagoons
Lagoons
Extended aeration
Activated sludge
Trickling filters
Spray irrigation
Septic tanks
Other
None . ...
Number of
installations
26
6
11
30
21
3
7
2
33
14
2
Size range, mgd
0.40-2.50
0.66-1.97
0.005-0.75
0.005-1.20
0.001-0.10
0.060
1.0-1.85
0.01-1.15
BOD reductions,
percent
90-99
98-99
91-98
87-99
85-99
99
92-99
SOURCE: Results of a questionnaire distributed to State water pollution control agencies. Data received from the States of
Alaska, Arizona, Delaware, Florida, Hawaii, Illinois, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Michigan, Missouri,
Nebraska, New York, Nevada, North Carolina, Ohio, Pennsylvania, Tennessee, Texas, Utah, Virginia, Wisconsin, and Wyoming.
64
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METRIC CONVERSION TABLES
Recommended Units
Description
Length
Area
Volume
Mass
Time
Force
Moment or
torque
Stress
Unit
metre
kilometre
millimetre
micrometre
square metre
square kilometre
square millimetre
hectare
cubic metre
litre
kilogram
gram
milligram
tonne or
megagram
second
day
year
newt on
newton metre
pascal
kilopascal
Symbol
m
km
mm
jum.
m2
km2
mm2
ha
m3
1
kg
g
mg
t
Mg
s
d
year
N
N-m
Pa
kPa
Application
Description
Precipitation,
run-off,
evaporation
River flow
Flow in pipes,
conduits, chan-
nels, over weirs.
pumping
Discharges or
abstractions,
yields
Usage of water
Density
Unit
millimetre
cubic metre
per second
cubic metre per
second
litre per second
cubic metre
per day
cubic metre
per year
litre per person
per day
kilogram per
cubic metre
Symbol
mm
m3/s
m3/s
l/s
m3/d
m3/ye»r
I/person
day
kg/m3
Comments
Basic SI unit
The hectare (10 000
m2) is a recognized
multiple unit and
will remain in inter-
national use.
The litre is now
recognized as the
special name for
the cubic decimetre.
Basic SI unit
1 tonne = 1 000 kg
1 Mg = 1 000 kg
Basic S7 unit
Neither the day nor
the year is an SI unit
but both are impor-
tant.
The newton is that
force that produces
an acceleration of
1 m/s2 in a mass
of 1 kg.
The metre is
measured perpendicu-
lar to the line of
action of the force
N. Not a joule.
of Units
Comments
For meteorological
purposes it may be
convenient to meas-
ure precipitation in
terms of mass/unit
area (kg/m3).
1 mm of rain =
1 kg/m2
Commonly called
the cumec
1 l/s = 86.4 m3/d
The density of
water under stand-
ard conditions is
1 000 kg/m3 or
1 000 g/l or
1 g/ml.
Customary
Equivalents
39.37 in.=3.28ft=
1.09yd
0.62 mi
0.03937 in.
3.937 X 10 3=103A
1 0.764 sq ft
= 1.196sqyd
6.384 sq mi =
247 acres
0.00155 sq in.
2.471 acres
35.314 cu ft =
1.3079cuyd
1. 057 qt = 0.264 gal
= 0.81 X 104acre-
ft
2.205 Ib
0.035 oz = 1 5.43 gr
0.01543 gr
0.984 ton (long) =
1.1 023 ton (short)
0.22481 Ib (weight)
= 7.233poundals
0.7375 ft-lbf
0.02089 Ibf/sq ft
0.14465 Ibf/sq in
Description
Velocity
linear
angular
Flow (volumetric)
Viscosity
Pressure
Temperature
Work, energy.
quantity of heat
Power
Recommended Units
Unit
metre per
second
millimetre
per second
kilometres
per second
radians per
second
cubic metre
per second
litre per second
pascal second
newton per
square metre
or pascal
kilometre per
square metre
or kilopascal
bar
Kelvin
degree Celsius
joule
kilojoule
watt
kilowatt
joule per second
Symbol
m/s
mm/s
km/s
rad/s
m3/s
l/s
Pa-s
N/m2
Pa
kN/m2
kPa
bar
K
C
J
kJ
W
kW
J/s
Comments
Commonly called
the cumec
Basic SI unit
The Kelvin and
Celsius degrees
are identical.
The use of the
Celsius scale is
recommended as
it is the former
centigrade scale.
1 joule = 1 N-m
where metres are
measured along
the line of
action of
force N.
1 watt = 1 J/s
Customary
Equivalents
3.28 fps
0.00328 fps
2.230 mph
1 5,850 gpm
= 2.120cfm
15.85 gpm
0.00672
poundals/sq ft
0.000145 Ib/sq in
0.145 Ib/sq in.
14.5 b/sq in.
5F
T ~17-77
o
2.778 X 10 7
kwhr =
3.725 X 10 7
hp-hr = 0.73756
ft-lb = 9.48 X
10 4 Btu
2.778 kw-hr
Application of Units
Customary
Equivalents
35.314 cfs
15.85gpm
1.83X 10 3 gpm
0.264 gcpd
0.0624 Ib/cu ft
Description
Concentration
BOD loading
Hydraulic load
per unit area;
e.g. filtration
rates
Hydraulic load
per unit volume;
e.g., biological
filters, lagoons
Air supply
Pipes
diameter
length
Optical units
Unit
milligram per
litre
kilogram per
cubic metre
per day
cubic metre
per square metre
per day
cubic metre
per cubic metre
per day
cubic metre or
litre of free air
per second
millimetre
metre
lumen per
square metre
Symbol
mg/t
kg/m3d
m3/m2d
m3/m3d
m3/s
l/s
mm
m
lumen/m2
Comments
If this is con-
verted to a
velocity, it
should be ex-
pressed in mm/s
(1 mm/s = 86.4
m3/m2 day).
Customary
Equivalents
1 ppm
0.0624 Ib/cu-ft
day
3.28 cu ft/sq ft
0.03937 in.
39.37 in..=
3.28ft
0.092ft
candle/sq ft
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U.S. ENVIRONMENTAL PROTECTION AGENCY • TECHNOLOGY TRANSFER
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