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Environmental Protection Agency
Technology Transfer Program
Upgrading Meat Packing Facilities
To Reduce Pollution
Waste Treatment Systems
Industry Seminar For
Pollution Control
Chicago, Illinois
June 12 & 13, 1973
Bell.GalyardtandWells
Architects-Engineers
Rapid City-Omaha
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ENVIRONMENTAL PROTECTION AGENCY
TECHNOLOGY TRANSFER PROGRAM
UPGRADING MEAT PACKING FACILITIES
TO REDUCE POLLUTION
WASTE TREATMENT SYSTEMS
INDUSTRY SEMINAR FOR POLLUTION CONTROL
CHICAGO, ILLINOIS
JUNE 12 AND 13, 1973
by
BELL-GALYARDT-WELLS
ARCHITECTS-ENGINEERS 5634 SO. 85th STREET RAPID CITY-OMAHA
OMAHA, NEBRASKA
PH. 402-331-0321
JOB. NO. 730402
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TABLE OF CONTENTS
SUBJECT
SECTION I
SECTION II
SECTION III
SECTION IV
SECTION V
SECTION VI
SECTION VII
SECTION VIII
PAGE
THE NEED FOR WASTEWATER TREATMENT 1
MICROORGANISMS AND THEIR ROLE IN WASTE TREATMENT 4
WASTE LOADS FOR THE MEAT PACKING INDUSTRY 6
PROCEDURES IN THE PLANNING, DESIGN AND CONSTRUCTION
OF A WASTEWATER TREATMENT SYSTEM 10
WASTEWATER TREATMENT METHODS FOR THE MEAT PACKING
INDUSTRY 16
A. ANAEROBIC PROCESSES 16
B. AEROBIC LAGOON SYSTEMS 22
C. ACTIVATED SLUDGE PROCESS 25
D. TRICKLING FILTERS 32
E. ROTATING BIOLOGICAL DISCS 34
F. IRRIGATION METHODS FOR THE MEAT PACKING
INDUSTRY 38
OPERATION AND MAINTENANCE OF WASTE TREATMENT PLANTS 43
CASE HISTORIES 48
A. AMERICAN BEEF PACKERS - COUNCIL BLUFFS, IOWA 48
B. IOWA BEEF PROCESSORS, INC. - DENISON, IOWA 49
C. FARMLAND FOODS - DENISON, IOWA 50
D. IOWA BEEF PROCESSORS, INC. - DAKOTA CITY,
NEBRASKA 54
E. LYKES BROTHERS PACKING PLANT - PLANT CITY
INDUSTRIAL PARK, FLORIDA 57
SURVEY OF EXISTING WASTE TREATMENT FACILITIES FOR
THE MEAT PROCESSING INDUSTRY 60
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APPENDIX
TABLE OF CONTENTS
American Beef Packers (Council Bluffs, Iowa) Page
1. Solids Screening Facility
and Hide Processing Settling Tank A-l
2. Hide Settling Tank A-2
3. Grease Flotation Tank A-3
4. Final Clarifier A-4
5. Aeration Basin A-5
Iowa Beef Processors, Inc. (Denison, Iowa)
1. Meat Processing Plant and
Lagoon Layout A-6
2. Anaerobic Lagoon A-7
3. Aerobic Lagoon A-8
Farmland Foods (Denison, Iowa)
1. Anaerobic Lagoon A-9
2. Pre-Aeration Basin, Trickling
Filters and Control Building A-10
3. Trickling Filter Arms and Media A-ll
4. Final Clarifier A-12
5. Chlorine Contact Tank A-13
6. Treated Effluent A-l4
Iowa Beef Processors, Inc. (Dakota City, Nebraska
1. Anaerobic Lagoon A-15
2. Rotating Biological Disc Building A-16
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3. Rotating Biological Discs A-17
4. Final Clarifier A-18
5. Chlorine Contact Tank A-19
Lykes Brothers (Plant City, Florida)
1. Aeration Basin A-20
2. Final Clarifier A-21
3. Polishing Lagoon A-22
Irrigation
1. Traveling Sprinkler System A-23
2. Traveling Sprinkler System A-24
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SECTION I
THE NEED FOR WASTEWATER TREATMENT
The discharge of industrial wastewater has recently 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 can cause irreparable harm.
The major components present in industrial waste discharges which 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 but may
adversely effect natural aquatic characteristics such as oxygen transfer and light
penetration. Setteable solids may have an adverse effect on stream organisms by
covering up the stream bed and forming sludge blankets which will decompose
anaerobically with the formation of odorous gases. Prevention of fish hatching
on the stream bed and creation of an anaerobic environment which will hamper bottom
dwelling microscopic animals may also result from settling solids. Moreover,
suspended solids will give the water a turbid complexion, causing limitation of
light penetration which in turn hampers aquatic veaetation relying on photosynthetic
reactions for survival. Large amounts of suspended solids will also increase the
requirements for treatment if the water is to be used for domestic supply.
In addition, organic matter, when discharged into a water course, will de-
compose, depleting the dissolved oxygen 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. More desirable species
of fish (trout, bass, etc.) which require dissolved oxygen levels near 5 mg/1
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or greater, will disappear to be replaced by the coarser types such as carp
and bullheads, which can survive dissolved oxygen levels near 2 mq/1. Below this
level, however, fish life will cease to exist. Other forms of life react in a
similar manner to decreasing levels of dissolved oxygen, and a shift towards
anaerobic species will eventually ocurr 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 alaae
growths become unacceptable. The two major nutrients commonly found in many types
of industrial discharge are nitrogen and phosphorous. Presence of these nutrients
may cause excessive growth of algae. When these heavy algae growths die, they
exert an oxygen demand which 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 greatly diminished by algae growth.
Temperature changes in water may cause adverse changes in the organisms and
affect stream reaeration. Fish and other forms of aguatic life have preferred
temperatures at which their life 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 also harmful. Moreover, deviation to higher than normal
temperatures result in the lowering of the stream's ability to reaerate itself, by
limiting the amount of dissolved oxygen 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 furthermore 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. Since the pH of most industrial discharges varies from neutral,
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effluents must be checked and often adjusted before beinq discharged into a stream.
To avoid degradation of water quality, industrial waste treatment must be
practiced in some form. This may take the form of complete treatment at the
industrial plant or partial treatment prior to discharge 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.
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SECTION II
MICROORGANISMS AND THEIR
ROLE IN WASTE TREATMENT
Treatment of industrial wastes 1s accomplished by living systems. The waste
flow furnishes food and environment to a mixed culture of microorganisms which
break down the organic constituents 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 (usinq carbon dioxide as a carbon source).
Heterotrophs may be aerobic, requiring free dissolved oxygen; facultative,
functioning with or without free oxygen; or anaerobic, requiring complete absence
of oxyqen. Other organisms of importance are fungi, protozoa and rotifers (higher
level animals which feed on bacteria and pi ay an important part in activated sludge).
Algae which are important in some waste treatment systems are autotrophic photosyn-
thetic 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 andxobtain energy
for synthesis and respiration is called metabolism. For heterotrophic aerobic
bacteria, the large molecules which make up the food supply must first be hydrolized
with carbohydrates going to sugars, protein to amino acids and fats into fatty acids.
These products can then be used by the cells for assimilation.
Anaerobic reaction involves the breakdown of orqanics to intermediate products
(chiefly organic acids) by one set of bacteria and the use of these products as
food by methane forming bacteria which further break down the waste. These bacteria
require higher temperatures to live than do aerobic bacteria and are called thermoph-
illic. When compared to aerobic processes, anaerobic reactions will not yield as
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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. This means
that the greatest removal of organics occurs at the time of greatest growth.
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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SECTION III
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, due to the many procedures and facets of meat process-
ing operations. A single plant may perform just a few or many of these proced-
ures. However, for all practical purposes, the industry may be divided into three
categories:
1. Slaughterhouses (killing and dressing)
2. Packinghouses (killing, dressing,curing, cooking, etc.)
3. Processing plants (processing with no killing operation)
Typical slaughterhouse and packinghouse wastes are generally high in
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 substantially reduce waste loads and may also
produce salable by-products. Furthermore, a well-managed program of in-plant
housekeeping practices is desirable both from a sanitary and wasteload stand-
point.
Waste loads which have been found through extensive study and research of
records to be typical of various types of meat packing plants are given in Table
I. A widespread sampling program is currently being conducted by the North Star
Research and Development Institute for the Environmental Protection Agency, for
the purpose of supplementing and updating this data.
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TABLE I*
STANDARD RAW WASTE LOADS
Type
Slaughterhouse
Per 1000 Ib LWK**
Packinghouse
Per 1000 Ib LWK**
Processing Plant
Per 1000 Ib Product
Flow
(gal)
696
1046
1265
BODc
(lb!
5.8
12.1
5.7
SS
(Ib)
4.7
8.7
2.7
Grease
(Ib)
2.5
6.0
2.1
industrial Waste Study by North Star Research and Development Institute
for Environmental Protection Agency
**Live Weight Kill
The valueslisted for slaughterhouses apply only to medium-sized plants
which 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
which carry out all processes associated with slaughtering, cuttinq, rendering,
and processing. Values for processing plants represent plants which cut and
process meat, but do no slaughtering or rendering.
These values are in general agreement with other values found in the
literature although the variations may have a wide range. Table II shows the
characteristics of the waste flow from numerous cattle and hog packing plants,
illustrating a typically wide variation from plant to plant.
In general the processes which are undertaken at a packing plant have a far
greater effect on the waste load factors than the size of the plant.
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TABLE II*
UNIT WASTE LOADINGS FOR MEAT PACKING PLANTS
(Pounds per 1,000 pounds of live weight)
Type of Animal
Slaughtered
Hogs
Hogs
Mixed
Hogs
Cattle
Hogs
Hogs
Mixed
Hogs
Mixed
Cattle
Mixed
Mixed
Mixed
Mixed
Mixed
Average
BOD
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
Suspended
Solids
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
Nitrogen
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
Grease
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
A limited number of studies have attempted to analyze the component parts
of the process. The fact that such wide variations in raw waste loads do exist
make data obtained from actual sampling of wastes similar to those anticipated
extremely useful and often economically beneficial in designing waste treatment
facilities.
Table III 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.
*An Industrial Waste Guide to the Meat Industry, U.S. Department of Health,
Education and Welfare.
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TABLE III*
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
Meat Cutting
Gut Washer
Curing Room
Curing Room Showers
Cured Meat Wash
Pickle
Sausage & Miscellaneous
Lard Department
By-Products
Laundry
Sol ids
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
Sus-
pended
220
3,690
8,360
560
80
6,780
610
15,120
1,800
1,720
920
560
180
1,380
4,120
Concentration in mq/1
Nitroc
Organic
134
5,400
1,290
158
586
822
33
643
83
255
109
2,750
136
84
186
56
en
NH,
6
205
40
10
30
18
2.5
43
12
25
17.5
37
4
25
50
5
Cl as
Ma Cl
435
6,670
640
290
290
230
1,620
360
19,700
29,flOO
6,200
77,800
880
230
1,330
BOD
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
—
6.9
7.4
6.0
7.3
6.7
7.3
5.6
7.3
7.3
6.7
9.6
*"An Industrial Waste Guide to the Meat Industry", U.S. Department of Health,
Education and Welfare
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SECTION IV
PROCEDURES IN THE PLANNING. DESIGN AND
CONSTRUCTION OF A UASTEWATER TREATMENT SYSTEM
A. 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 previously, meat packing wastes vary con-
siderably 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 halfhour intervals continuously for three days and preferably
one week. These samples should be combined for every twenty-four hour period
to provide an accurate composite of the waste. A weir or similar measuring
device should be installed at each sampling station in order to provide a
means of determining the rate of flow when each sample is taken. The samp-
ling 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 twenty-four hour interval. It is important that the laboratory sel-
ected to perform the tests be experienced in the analyzing of wastewater
samples. The most frequently performed determinations are BODs (5-day Bio-
chemical Oxygen Demand), COD (Chemical Oxygen Demand), settleable solids, sus-
pended solids, volatile suspended solids, grease, Kjeldahl nitrogen, and pH.
B. DEVELOPMENT OF DESIGN CRITERIA
Once the results of the sampling program have been fully reviewed and
analyzed, the design engineer is able to establish the design criteria.
These factors are usually determined on the basis of 1000 pounds of live
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weight kill or per head. Any anticipated change in slaughtering or processing
operations must be considered, as it will affect the current waste character-
istics. If flows and BOD appear to be excessively high as sampled, a con-
scientious 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/1000 Ibs. live weight/day)
Design maximum flow (gallons per day)
Design BOD (pounds/1000 Ibs. live weight kill)
Design suspended solids (pounds/1000 Ibs. live weight kill)
Design work week (days/week)
C. EFFLUENT REQUIREMENTS
1. Environmental Protection Agency Guidelines. The following effluent
guidelines listed in Table IV for discharges in the meat processing industry
are based on the application of the "best practicable control technology cur-
rently available". These limitations reflect the Agency's best technical
judgement of the effluent levels which can be maintained through the appli-
cation of the highest levels of pollution control that are currently available
and practicable.
TABLE IV**
Meat Processing BODs* Suspended Solids*
Slaughterhouse 0.17 0.23
Packinghouse 0.26 0.35
Processing Plant Only 0.26 0.26
The above values represent minimum limitations only, and generally will be less
stringent than state restrictions.
2. State Requirements. Effluent requirements as determined by a state will
vary considerably throughout the country, and will also vary within an individ-
ual state, depending upon the water quality standards for the receiving stream
* Values expressed in terms of pounds/1000 pounds of live weight killed.
** Effluent Limitation Guidance for the Refuse Act Permit Program, Environmental
Protection Agency, July 27, 1972.
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into which the treated wastewater will be discharged. By July 1, 1977, all
municipal waste treatment facilities must provide a minimum of secondary treat-
ment, and all industries must be applying the best practicable control technology
available. However, in some states, tertiary treatment is already required on
some streams and lakes, with BOD and suspended solids limitations of 5 mg/1 or
less.
3. Municipal Requirements. Most municipalities have ordinances which place
limitations on the characteristics of the wastewater which may be discharged
into the municipal sewer system. These limitations are set to prevent operat-
ional problems at the municipal waste treatment facility and to prevent the
plant from becoming overloaded. Any industry which fails 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 the wastes.
Also, further reduction of BOD and suspended solids would be economically advant-
ageous. Screening, grease skimming, and solids removal are perhaps the most im-
portant 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. This cost can become extremely high, particularly 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 carefully studied.
D. DEVELOPMENT OF ALTERNATE TREATMENT METHODS
Once design criteria and effluent requirements have been established,
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various methods of waste treatment which will provide an effluent meeting
those standards are investigated by the design engineer. Several addit-
ional factors must be considered in making a choice. They include land
availability, proximity to residential or commercial areas, initial con-
struction cost, operation and maintenance costs and ease of operation.
Meat packing plants which are 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 appro-
val of design criteria and layout will facilitate later review by these
agencies.
E. DESIGN OF THE TREATMENT SYSTEM
Preparation of final plans and specifications for construction is be-
gun by the design engineer once the selection of the treatment system is
made. At this stage, it is important that reliable topographical inform-
ation is obtained, providing ground elevations, location of existing prop-
erty lines, building and sewers, sewer invert elevations, and a benchmark
elevation on which to base proposed construction. 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 char-
acteristics which should be used in specifying equipment.
Once the treatment units have been sized, an overall site layout can
be developed, leaving adequate 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 to be considered in making the layout, permitting
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additions to be made to the facilities with minimum disruption of the ex-
isting 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 are generally 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 con-
struction.
F. 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 any qualified contractor in the vicinity, and plans and specifications
are issued to any of these contractors upon request, for a period of three
weeks to a month. Sealed bids are then opened by the owner or his repre-
sentative 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 conformance of construction with plans and specifi-
cations is essential for correct and reliable functioning of the system.
Any deviation from the contract documents should be made only with the
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approval of the design engineer. Equipment 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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SECTION V
HASTEHATER TREATMENT METHODS FOR
THE MEAT PACKING INDUSTRY
The secondary treatment methods commonly used for the biological treatment
of meat processing waste flows include: (1) anaerobic processes; (2) aerobic
lagoon systems; (3) variations of the activated sludge process; (4) high rate
trickling filters; and (5) rotating biological discs. All of these treatment
processes are capable of providing complete treatment and can achieve BOD re-
ductions of 70% to 95% and suspended solids reductions of 80% to 95%. Each
system has advantages and disadvantages, and generally, the degree of treatment
required, together with site location and limitation, capital costs and oper-
ational costs will dictate the selection of the treatment system. The follow-
ing discussion of each system describes the treatment process, equipment util-
ized, as well as advantages and drawbacks. In addition, disposal of treated
wastewater by irrigation methods is discussed as an alternate to tertiary treat-
ment.
A. ANAEROBIC PROCESSES
Treatment by the anaerobic process is often used for wastes originating from
meat processing plants, since the nature of the waste lends itself to this type
of biological activity. Elevated temperatures (85° - 950), and high concentrat-
ions of BOD and suspended solids—typical characteristics of the waste flow from
a meat packing plant—are necessary for successful anaerobic treatment. As prev-
iously discussed, 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. Nevertheless, 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 utilized: (1) anaerobic la-
goons, and (2) anaerobic contact units.
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1. Anaerobic Lagoons. Anaerobic lagoons are widely used for treatment of
meat packing wastes and function extremely well when the wastes have the desired
characteristics. Typically, meat packing wastes have an appreciable amount of
fats and proteins, high concentrations of nutrients, and an elevated temperature--
all of which are essential for good anaerobic biological treatment.
Such lagoons are designed with a low surface to volume ratio in order to
conserve heat in the pond. Depths are much deeper than aerobic ponds, ranqinq
from 12 to 17 feet. Loadings range from 12-25 pounds BOD/1000 cubic ft. with
15-20 pounds BOD/1000 cubic ft. frequently used in meat processing waste applic-
ations. 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 which contains active microorganisms 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 is generally not considered necessary, although it has
been used in some installations.
Site conditions which must be evaluated when considering anaerobic lagoons
are: (1) 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 down wind; and (2) 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 development of a cover, paunch manure or normally recovered grease
may be by-passed to the lagoon for a short period. Since high winds may disturb
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the scum layer and result in heat loss and odor problems, 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 adversely effect 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 are currently being investigated. A
major consideration in constructing a cover is providing an adequate gas collect-
ion system to trap the methane gases which rise to the surface. 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 anaerobic 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 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 re-
moval is not a maintenance problem.
Advantages of an anaerobic lagoon system are low initial cost, ease of oper-
ation, 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 sulphates 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 concentrations of 3 to 5 mg/1, depending upon pH,
and water quality standards in most states limit the concentration to 2 to 5 mg/1.
-18-
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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 is generally followed by some form of aerobic
system. However some states will not permit the use of anaerobic lagoons or
are requiring that they be provided with a cover.
2. Anaerobic Contact Process. The anaerobic contact process consists
basically of an anaerobic digester with mixing equipment, 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 recir-
culation of seed sludge permits short retention periods, ranging from 6 to
12 hours. Solids retention time for a high degree of treatment is approxim-
ately 10 days at 90 degrees 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 Ib. BOD/ft.3/day at approximatley 90° to 95° F. Flow equalization is
employed in order to maintain a uniform feed rate to the digester. This is
necessary because of the short contact time involved in the process. Either
draft tube or turbine-type mixers are utilized to provide complete mixinq.
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 twenty inches of mercury
-19-
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Is maintained In a vessel which 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 pro-
cess involves passing diffused air through the waste to scrub off the gas.
This method is less expensive but has more operational problems than the
vacuum process.
The clarifier receiving the sludge should be provided with a well de-
signed recirculation system in order to move the light floe and to avoid a
temperature loss.
Treatment efficiencies of 85 to 93% removal of BOD can be obtained with
the anaerobic contact system, but generally additional aerobic treatment is
required. The overall cost of such a system usually lies between that of
anaerobic lagoon system and an activated sludge plant.
An anaerobic contact system is currently in use at the Wilson Certified
Foods Plant in Albert Lea, Minnesota. This facility consists of a flow
equalizing basin, two digesters of approximately 12 hours detention time
which are loaded at 0.156 Ib. BOD/ft.^/day, two vacuum degasifiers, two
sludge separation units (clarifiers), and two oxidation ponds receiving
the separation effluent. The separators are designed for a detention time
of one hour, based on total flow including recirculation. The recirculation
rate is approximately one third of the raw waste flow.
Table V is actual operating data taken from the Wilson & Co. ?naerobic
contact system. BOD removal is approximately 91% through the anaerobic
contact process and 98% in the stabilization ponds. Good removals (80%)
were 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.
-20-
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TABLE V
ANAEROBIC CONTACT SYSTEM
WILSON CERTIFIED FOODS, INC.
ALBERT LEA, MINNESOTA
Average operating data (all killing days in I960)*
Flow, Gal Ions
BOD
Suspended Solids
Suspended Volatile Solids
Total Solids
Total Solids-Water Supply
Total Solids after deduct-
ing TS in Water Supply
Total Volatile Solids
Total Volatile Solids in
Water Supply
Total Volatile Solids
after Deducting TVS in
Water Supply
Raw Waste
1,410,000
Raw Waste
mg/1
1381
998
822
2100
560
2540
1700
300
1400
Pounds
16220
11610
10370
36500
6500
30000
19980
3520
16460
Anaerobic Process
Effluent
1,410,000
Anaerobic Process
Effluent
mg/1
129
198
153
2080
560
1520
800
300
500
Pounds
1517
2325
1800
24450
6500
17950
9400
3520
5880
Pond
Effluent
772,000
Loss in
Hond
638,000
Plant Effluent
Corrected for
Seepage
mg/1
26
23
20
1076
560
516
367
300
67
Pounds
304
268
232
12500
6500
6000
4310
3520
790
*"An Industrial Waste Guide to the Meat Packing Industry," U.S. Department
of Health, Education and Welfare.
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B. AEROBIC LAGOON SYSTEMS
1. General. Treatment of domestic and industrial wastes, including
those from meat packing plants,is frequently accomplished in aerobic lagoons.
Two types of lagoons are generally classified as being aerobic: (1) aerated
lagoons, which mechanically introduce oxygen by aeration; and (2) oxidation ponds
which are lightly loaded and rely on sunlight and wave action to accomplish
bio-oxidation and photosynthesis. Aerobic lagoons are frequently utilized to
provide additional treatment to the effluent from an anaerobic laqoon system.
2. Aerated Lagoons. Aerated lagoons are usually designed with de-
tention times of 2 to 10 days, have liquid depths of eight to fifteen
feet, and utilize 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 which 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 is dependent upon temperature, detention
time and influent waste characteristics. Treatment efficiency decreases as
temperature decreases. In northern climates, lower BOD reduction is exper-
ienced during the winter months. Aerated lagoons treating meat packing wastes
are generally designed to achieve an average BOD reduction of 50 to 60%.
Power requirements are a major consideration and treatment facilities
handling a high industrial flow may utilize several hundred horsepower.
Facilities for small meat processing plants nay use no more than twenty
horsepower.
When aerated lagoons are used in series with anaerobic lagoons, suff-
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icient oxygen Is added to restore the waste to an aerobic state, Including oxi-
dation of sulfides, and to provide for the additional biological treatment.
The most significant advantage of an aerated lagoon system Is its rela-
tively small land requirement. 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.
3. Oxidation Ponds. Oxidation ponds consist of relatively shallow, light-
ly loaded lagoons (20 to 40 Ibs. 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 widely used in the past for both domestic and industrial wastes. As
effluent quality requirements become more stringent, however, the treatment eff-
iciency achievable in oxidation ponds may be inadequate for discharge into a part-
icular receiving stream. In areas where the effluent would flow into a recreation-
al body of water, the BOD and suspended solids must usually be reduced to 5 mg/1
or less, and ammonia reduced to less than 3 mg/1. Discharge may even be prohibited
entirely. In these cases, the effluent from the oxidation pond must be disposed
of by irrigation or evaporation.
Even when effluent requirements are less stringent, problems may develop due
to the development on the lagoon surface of algae growth. This algae escapes
with the pond effluent and creates an undesirable appearance, odor and taste in
the receiving stream.
Oxidation ponds which treat wastes from the meat processing industry are
frequently preceded by anaerobic lagoons or anaerobic lagoons in conjunction with
aerated lagoons. Even with this prior treatment, the BOD remaining in the flow
entering the oxidation pond may still be substantial. Since the loading rate to
oxidation ponds is generally kept quite low in order to minimize odor problems
-23-
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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 four to eight 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 two feet prior to 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 BOO per acre have been used
for meat processing wastes with reasonably high initial treatment efficiencies;
however, odor problems have usually occurred and the quality and efficiency of
the lagoons have frequently deteriorated after a period of several years. Be-
cause of this, 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 de-
sign, as it is essential that the compacted earth below the maximum water sur-
face be essentially impermeable. Sandy or other granular soils are unsuitable
for lagoon construction and require some type of liner. Due 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 generally not necessary to chlorinate the effluent from a stabilization
pond, although it may be required whenever effluent standards for pathogenic bac-
teria are not met.
The large surface area required for adequate treatment of meat processing
-24-
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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, and weakening of dikes caused
by erosion or burrowing by rodents can result in potential flooding of surr-
ounding 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 succeeding degrees of treatment. Stabilization ponds which follow
anaerobic or aerated lagoons will generally have an average efficiency of
approximately 80% (in the first stage) and as high as 90% in the summer and
70% or less in the winter months. Efficiency tends to drop off somewhat
in successive stages, reaching as low as 50% in a third stage aerobic pond.
Stabilization ponds provide an excellent means of treating meat pro-
cessing wastes prior to use of the wastewater for irrigation purposes. However,
due to increasingly stringent effluent quality standards, the discharge from a
stabilization pond may frequently not be satisfactory for discharge into a
receiving body of water.
C. ACTIVATED SLUDGE PROCESSES
Probably one of the most efficient and widely used systems of biological
treatment of wastewater is the activated sludge process. Aeration of waste-
water 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 UseH as food
-25-
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by the microorganisms. There are several variations of the activated sludge
process, four of which are shown in Figure 1 and all of which are described
below.
SLUDGE
THICKENING
DIGESTION
SECONDARY
CLARIFIER
SECONDARY __
CLARIFIER /EFFLUENT
WASTE EXCESS
SLUDGE
BASIC SYSTEM
STEP AERATION
RAW
WASTES
WASTE EXCESS
SLUDGE
v WASTE EXCESS
X SLUDGE
(SMALL OR NONE)
CONTACT STABILIZATION
EXTENDED AERATION
FIGURE NO I
VARIATIONS OF THE ACTIVATED SLUDGE PROCESS
-26-
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1. Conventional Activated Sludge. The conventional activated sludge process
is composed of four functional steps: (1) primary sedimentation to remove
settleable solids; (2) aeration of a mixture of waste and biologically active
sludge; (3) separation of the biologically active sludge from the treated
waste by sedimentation; and (4) recycle of this settled biological sludge.
Following sedimentation in a primary clarifier, the wastewater is
mixed with recycled sludge in an aeration basin. This insures that adequate
numbers of microorganisms are present to carry out the degree of waste stab-
ilization desired. In the aeration basin the mixture of wastewater and re-
cycled sludge is aerated for a specified length of time to provide 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% to 95% and can produce a stable effluent with little nitrification.
The conventional activated sludge is adversely affected by the occasional
spills or dumps of high organic wastes such as blood. Also the widely varying
flows can be troublesome.
Due to problems encountered in the basic activated sludge system when
dealing with a particular waste or when a higher degree of treatnent is
desired, a number of modifications have been devised.
2. 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
-27-
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with the air requirements of the system. Reducing the air applied in no way
arfects the biological process in the basin as long as sufficient amounts of
air are present. It 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 requirerrerts
over the length of the tank, allowing higher BOD loadings, shorter detention
times and more efficient use of applied air.
3. Contact Stabilization. The BOD in sewage is rapidly adsorbed by
microorganisms after initial contact between waste and organisms. In the
conventional activated sludge system, the time and a^r necessary to stabilize
this adsorbed material is provided in the same tank where original contact
between waste and organisms was made.
The contact stabiliztion process provides separate tanks for initial
microorganisms waste contact and stabiliztion. The microorganism waste contact
part of the process generally requires 15 to 30 minutes. Following the tank in
which initial contact takes place, a clarifier is user! 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 stre?m.
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.
-28-
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4. Completely Mixed Activated Sludge. By providing enough mixing in the
aeration tank to completely mix 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 quickly mixed and distributed evenly throughout the basin, reducing the
chance of system upset commonly associated with conventional systems.
5. Extended deration. 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 avail-
able to the organisms, nearly complete oxidation occurs for microorganisms
and BOD removals are high. Removals in excess of 95% 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 to 100% 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.
6. 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 eight to ten days is required for the nitrifying
organisms to establish themselves in sufficient numbers to accomplish
any appreciable degree of nitrification. Usually, extended aeration systems
-29-
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designed to accomplish nitrification are designed for sludge detention tines in
excess of 10 days. Although liquid detention times in the system are generally
approximately 24 hours, the sludge age may be controlled 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 one pound of ammonia nitrogen to nitrates. This results in a sub-
stantial increase in air requirements over those required for BOD reduction
alone, necessitating the installation of larger, more expensive aeration
equipment.
Extended aeration systems which 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%; 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 discharged to a receiving stream. Further, this chemical 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.
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.
7. Activated Sludge Treatment for Meat Processing Hastes. All of the
-30-
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previously mentioned activated sludge systems may be used to treat wastes
characteristic of the meat packing industry. The particular system chosen
will depend upon the degree of treatment 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 utilize anaerobic lagoons for reduction
of BOD. The effluent from these lagoons is generally 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 previously are presented in Table VI below. ROD loadings
to aeration tanks are calculated usinq the influent wastewater BOD only.
Loadings are expressed as pounds applied per day per 1000 ft.3 of aeration tank
volume and pounds of BOD per day per pound nixed liquor suspended solids 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 is usually expressed as a percentage of the daily average flow.
-31-
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TABLE VI
GENERAL LOADING AND OPERATIONAL PARAMETERS FOR
ACTIVATED-SLUDGE PROCESSES*
Process
BOD Loading
Ib BOD Ib BOD
lOOOcuft.
High Rate
(Complete Mixing )
Step Aeration
Conventional
(Tapered Aeration)
Contact
Stabilization
Extended Aeration
100 up
30-50
30-40
30-50
10-30
Ib MLSS
0.5-1.0
0.2-0.5
0.2-0.5
0.2-0.5
0:05-0.2
Aeration Average
Period Peturn
Hour Sludge Rates
percent
2.5-3.5
5.0-7.0
6.0-7.5
6.0-9.0
20-30
100
50
30
100
100
BOP
Efficiency
percent
85-90
90-95
95
85-90
85-90
D. TRICKLING FILTERS
Trickling filters are commonly used for biological wastewater treatment.
With this system, wastewater which has undergone primary settling is sprayed
over beds of rock or other media to achieve contact between microorganisms
present on the surface of the media and organic material in the wastewater.
A trickling filter is composed of three main components: (1) the rotary
distribution arms; (2) the media: and (3) an 'jnderdrainsystem.
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 uniformly distribute the wastewater flow over the filter media. Where suff-
icient head is not available, water must be pumped to the distributor.
The filter media provides both a surface for the biological growth
and also voids for movement 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
*Water Supply and Pollution Control, Clark, Viessman and Hammer,International
TextDooK LO., is/i, pp su/.
-32-
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recently been developed and are on the market. They include various clastic
media and also 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.
The underdrain system provides the means to carry away the filter effluer.t,
allows circulation of air thorugh the filter bed and provides structural support
for the filter media.
Filters utilizing light weight plastic media are able to utilize much
deeper beds (up to 21.5 feet) than for those utilizing 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 below.
PRIMARY
SEDIMENTATION
FILTER
FINAL
SEDIMENTATION
RECYCLE
PRIMARY
SEDIMENTATION
HIGH RATE FILTER
FILTER
TO FOLLOWING
TREATMENT SYSTEMS
ROUGHING FILTER
FIGURE NO. 2
-33-
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BOD loadings to trickling filter systems are generally expressed either
as pounds of BOD per 1000 cu.ft. 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 gallons per minute per square foot of filter area. The
hydraulic loading is computed usinq both the raw wastewater flow plus the re-
circulated flow.
The high rate trickling filter is capable of achieving BOD reductions as
high as 90% 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.
E. ROTATING BIOLOGICAL DISCS
The use of rotating biological discs is a new approach to the treatment
of meat processing wastes. The discs 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 v/ork on the rotating biological discs in the United States began
in 1965. Utilization of the discs in the treatment of meat processing wastes
is recent, and to date, no operational data is available except on a pilot plant
scale. A large treatment facility for the Iowa Beef Processors plant at Dakota
City, Nebraska, is currently under construction and should be in operation later
this year.
The rotating biological discs system consists of large diameter, light-
weight plastic or high density styrofoam discs, which are mounted on a
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horizontal shaft and placed in a semicircularshaped tank containing wastewater.
Organisms present naturally in the wastewater adhere to the rotatinq surfaces
and begin to multiply. As the discs rotate through the wastewater, waste-
water adheres to the discs and then trickles down the discs absorbing
oxygen. The aerobic organisms present in the wastewater then utilize the
oxygen to reduce the oraanic matter in the wastewater. As the discs continue
to rotate through the wastewater, the organic material is further reduced. The
discs 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 discs. This minimizes clogging problems and maintains a nearly
constant growth of organisms on the discs. The mixing action of the discs
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 discs.
BOO removal and oxidation of ammonia nitrogen has been found to be
directly proportional to the hydraulic loading on the disc units. At a
specific hydraulic loading, a given percentaae of BOD is generally removed
even with fluctuation of the influent BOP. As a result, the principal design
criterion is hydraulic loading.
Wastewater temperature will affect rotatinq biological disc efficiency,
but this affect is negligible for normally encountered ranges of temperature.
Wastewater temperatures in the range of fiO° to 80° F. have little affect on
disc treatment efficiencies. Waste temperatures from packing plants will
generally average 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 staqes
has been shown to enhance the overall treatment of a wastewater, because the
organisms that develop on each successive stage (disc) are adapted to treat
-35-
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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
nitrogen form is toxic to aquatic life.
The rotating biological discs should be enclosed to protect the organisms
from cold temperatures and to help control odor emissions. As previously
discussed, waste treatment efficiencies are reduced considerably when temp-
eratures fall below 55° - 60° F. The enclosure helps to prevent winter
weather from adversely affecting the treatment system. The enclosure will
also help to control odor problems which 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 »ype of enclosure that is generally used for a rotating biological
disc system is a timber or concrete building with a poured concrete floor.
Steel construction is not generally suitable since the air within the rotat-
ing biological disc building has a high degree of humidity.
A simplified typical flow schematic illustrating the treatment of a
meat packing waste using rotating biological discs is shown in Figure 3.
The raw wastewater flows into anaerobic lagoons or 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 discs where
the organic material is converted to a biological floe which can be settled
-36-
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in the final clarifiers. The wastewater is then disinfected by chlorination,
prior to discharge to the receiving stream.
Figure No. 3
ANAEROBIC
LAGOONS
OR PRE-
TREATMENT
FINAL
CLARIFIERS
INFLUENT
ROTATING
BIOLOGICAL
DISCS
FIGURE NO. 3
TYPICAL FLOW SCHEMATIC
ROTATING BIOLOGICAL DISCS
Rotating biological discs can also be used in completely aerobic systems.
The discs must be preceded by adequate grease removal. The number of staoes
of dies required will depend upon the desired degree of treatment. The system
will also include a final clarifier and chlorination. /* system of this type
is currently treating poultry wastes with the effluent discharged to the
municipal sewer system. With four staoes. 98% ROD reduction is achieved.
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F. IRRIGATION METHODS FOR THE MEAT PACKING INDUSTRY
As water quality standards become more stringent, increasingly elaborate
and complex treatment 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
operation and maintenance costs, when compared to a highly sophisticated terti-
ary 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 which can be used for ultimate disposal of wastewater: spray irri-
gation, overland runoff, and rapid infiltration.
1. Spray Irrigation. Spray irrigation is defined as the controlled spray-
ing 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. Since spray irrigation
is generally limited 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 infil-
tration 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
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of a soil involves the intermittent application of wastewater with intervening
rest periods. If wastewater were to be continuously applied to the soil, an
equilibrium infiltration rate would eventually be established—a rate which is
generally too small to be acceptable.
Another important factor in spray irrigation is the necessity of maintain-
ing aerobic conditions in the soil, in order to insure proper treatment of the
wastewater. Consequently, application rates should be significantly less than
infiltration capacities if unsaturated soil conditions--!'.e. aerobic conditions--
are to exist in the infiltration surface.
Groundwater characteristics must be thoroughly studied before spray irri-
gation is commenced in order to preclude the possibility of groundwater contami-
nation. The soil mantle between the ground surface and the water table must be
of sufficient depth to ensure treatment of the wastewater prior to reaching the
groundwater. Caution must be exercised where geologic conditions include fract-
ure zones—i.e. limestone formations—for rapid water movement with little fil-
tration may result in contamination. Minimum depths from the ground surface to
the groundwater table may vary from 10 feet to 15 feet depending on the infil-
tration rate of the particular soil.
Spray application rates are usually expressed in terms of inches of liquid
depth per unit of time. Net weekly applications may range from 0.2 inches to 6.0
inches, but the most common application rate is 2.0 inches. Application rates
and weekly application amounts are generally selected on the basis of the capacity
of the vegetation to take up nutrients. Usually this results in application rates
being less than infiltration rates.
Many different crops have been successfully used 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 roll-
-39-
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ing. Land areas characterized by steep slopes will become eroded before infil-
tration can take place.
Spray equipment will vary, depending on the site topography and crop. (Con-
ventional aluminum irrigation pipe is commonly used.) For large permanent facili-
ties, the pipe network can be buried, with only risers and spray nozzles appear-
ing above the ground surface. At sites with flat or rolling terrain, center
pivot irrigation systems can be used successfully. Self-propelled traveling
sprinkler systems are another common type of equipment.
2. 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 pass-
age 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 sub-
soils.
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. However, precipitation may also have a
beneficial effect on an overland runoff site by acting as a flushing or cleansing
agent removing material deposited by the wastewater.
One of the major design considerations in designing an overland runoff sys-
tem is achieving and maintaining proper overland flow. Flow which is too slow
can result in ponding and anaerobic conditions; too rapid a flow will result in
inadequate contact time between the wastewater 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.
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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 nozz-
les 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 fes-
cue.
3. Rapid Infiltration. Rapid infiltration is similar to spray irrigation
in that the wastewater is intended to infiltrate the soil and become treated dur-
ing percolation. However, with a rapid infiltration system, the application
rates are substantially higher and the wastewater is applied by spreading or
flooding rather than by spraying. Precipitation is not a significant factor,
since 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 groundwater table is of major concern in rapid infiltration
just as it is in spray irrigation, due to the possibility of groundwater contami-
nation. 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 per day to
2 feet per day.
4. Irrigation Design Report. Prior to the time an irrigation system is
placed in operation, most state regulatory agencies will require an irrigation
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design report. This report must usually include maps and diagrams of the area
affected by the irrigation system as well as any additional material which is
pertinent 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.
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SECTION VI
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
and 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 which utilize complicated treatment facilities and plants
which use 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 de-
signed into the system.
A good program of waste flow sampling can help substantially in ob-
taining the optimum degree of treatment. In addition to providing the re-
quired data for regulatory agencies, a complete record of treatment factors
may help the operator cope with present inconsistencies and future expan-
sion in the waste treatment system. Familiarity with the physical appear-
ance of the raw influent and of the well-treated or under-treated effluent
flew will provide an indication to the operator of an upset or change which
will require more detailed and careful sampling. A reliable and workable
arrangement must be made for the necessary analytical work that is reouired,
whether it is performed by company personnel or by an outside agency.
The operational problems to be encountered will depend upon the waste
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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 operation of treat-
ment plants .such as published by the Water Pollution Control Federation
should be readily available as a referencefor all employees associated
with the waste treatment facilities. Such manuals contain information on
the causes and cures of many operational difficulties encountered in usual
types of treatment. Operational practices for anaerobic and aerobic lagoons
may be found in numerous text books or published articles in wastewater
journals. Furthermore, 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 in-
spection and maintenance should be established, based upon the nature and
needs of the equipment. All literature from the manufacturer relating to
equipment upkeep should be filed away for future reference after being studied
by the operations staff. A supply of spare parts, as recommended by the manu-
facturer, should be kept on hand at all times.
If possible, daily attention should be given to the operation and maint-
enance of the system. Simple systems may require little day to day care,
but should be checked on a regular basis. Care of the treatment site is
also important. Mowing should not be neglected, fences and gates should
be kept in good repair, and utilities maintained.
The following schedule lists some of the many types of maintenance re-
quired on various segments of the complete system. It should serve only
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to provide a base upon which each Individual plant operator may build his own
operation and maintenance programs.
TYPICAL OPERATION AND MAINTENANCE PROGRAM
FOR
WASTE TREATMENT SYSTEM
A. 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 over-heating 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. C^eck electric motor pump drives periodically.
9. Alternate pumps on a weekly basis if automatic alternation is not
provided.
B. SCREENING FACILITIES
1. Check daily to determine if screens require cleaning.
2. Rake screens and dispose of material by burying or other suitable
means.
C. SEDIMENTATION TANKS (CLARIFIERS)
1. Check tanks and equipment several times daily for proper operation.
2. On a regular basis, 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 lubri-
cants.
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5. Drain tanks annually and inspect all systems for wear and corrosion.
Replace badly worn equipment and adjust all chains.
D. TRICKLING FILTERS
1. Inspect rotating arm nozzles daily for clogging; clean as required.
2. Check bearings and lubricate in accordance with manufacturer's rec-
ommendations.
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.
E. 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.
F. 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 equip-
ment.
G. SAMPLING
1. Check raw flow rate weekly, preferably daily.
2. Perform periodic settleable solids tests on influent and effluent flow.
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3. Perform daily dissolved oxygen, BOD, suspended solids, and settle-
able solids tests on activated sludge systems to insure proper
operation.
4. Run BOD, suspended solids, D. 0. tests daily or bi-weekly at
trickling filter plants but not less than 2 times a week.
5. Run tests for nitrates, ammonia nitrogen and organic nitrogen,
and possibly phosphates on samples collected preceding and follow-
ing treatment at regular intervals.
6. Perform daily tests for settleable solids, suspended solids,
total and volatile solids on samples from sedimentation units.
Check sludge for total and volatile solids to provide inform-
ation required for proper operation of sludge recirculation and
drawoff systems.
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.
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SECTION VII
CASE HISTORIES
A. AMERICAN BEEF PACKERS. COUNCIL BLUFFS. IOWA
The American Beef Packers 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 build-
ing. Waste treatment facilities included with the plant construction con-
sisted of an air flotation tank to remove grease from the slaughtering-pro-
cessing waste stream, followed by an aerated lagoon. Effluent from the
flotation tank and the hide processing building were discharged separately
to the aerated lagoon prior to 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 due 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 which 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 which was designed to upgrade the existing facilities was an
extended aeration system based upon the following design data:
BOD Loading 18,000 Ibs/day
Design Flow 1.5 MGD
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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
being supplied to the basin was considered insufficient for both the necessary
mixing and 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 was constructed, with provisions for sludge return
in an amount equal to 100% 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 1n Figure 4.
Grease skimming and solids screening are provided for the hide processing
effluent (brine curing) prior to discharge to the aeration basin.
The eight, 40-hp aerators were installed in the aerated basin prior to com-
pletion 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 including the re-
circulation 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 included in the Appendix.
B. IOWA BEEF PROCESSORS. INC.. DENISON, IOWA
Iowa Beef Processors, Inc., recognized in 1966 the need for secondary waste
treatment for their beef slaughtering plant at Denison, Iowa. An anaerobic-aero-
bic lagoon system was determined to be the best type of treatment facility, and
was designed using the following factors:
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BOD Loading 9,600 Ibs/day
Design Flow 720,000 gpd
Anaerobic Lagoon Loading —15 Ibs BOD/1000 ft3
Depth of Anaerobic Lagoon 15 feet
Assumed Efficiency 65%
1st Stage Aerobic
Lagoon Loading 150 pounds BOD/acre
2nd Stage Aerobic
Lagoon Loading 50 pounds BOD/acre
Figure 5 shows the schematic layout and flow diagram for the system. Plant
waste undergoes pretreatment in an air flotation unit, while pen wastes flow
through a settling basin prior to discharge to the lift station. The combined
pen and plant wastes flow through a mechanically cleaned bar screen and meas-
uring 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 received further treat-
ment in a second-stage aerobic pond prior to discharge into the Boyer River.
Sampling data obtained by the State of Iowa Hygienic Laboratory indicates
that the lagoon system has performed well since its completion in November
1968. BOD removal efficiencies of over 80% have been consistently achieved
in the anaerobic lagoons, and the overall efficiency of the system is approxi-
mately 98%.
The approximate 1967 cost of construction for the facility was $ 110,000,
with much of the labor performed by Iowa Beef construction personnel.
With an operating anaerobic lagoon treatment efficiency of 80% rather than
the assumed design value of 65%, 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.
C. FARMLAND FOODS, DENISON. IOWA
The wastewater treatment system serving the hog processing plant owned by
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FLOTATION UNIT
JBAR SCREEN &
MARSHALL FLUME
LIFT STATION
ANAEROBIC
LAGOON
ANAEROBIC
LAGOON
AEROBIC
LAGOON
AEROBIC
LAGOON
0
SECONDARY
AEROBIC LAGOON
v EFFLUENT TO
*BOYER RIVER
FIGURE NO. 5
FLOW SCHEMATIC
IOWA BEEF PACKERS, INC.
DENISON, IOWA
-------
Farmland Foods, Dem'son, Iowa, was designed to treat the varied waste flows
from the killing floor, holding pens, blood recovery system, rendering, and
processing operations and also domestic sewers.
The plant kills 5,000 hogs per day, of which 40% are usually kept for
further processing operations, the rest being shipped. The processing oper-
ations include cutting and processing into hams, bacon and picnics. Render-
ing 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 of 1969. The facility
now has been in operation for approximately 2-1/2 years.
The raw waste criteria employed in the design of this treatment system
is given below:
RAW WASTE DESIGN CRITERIA1
BOD Loading 21,500 Ibs BOD/day
FLOWS
Average 850,000 gpd
Maximum Daily 1,000,000 gpd
Maximum Hourly 1,500,000 gpd
The flow diagram for the treatment facilities is shown in Figure 6.
The wastes from the kill floor are pumped to an air flotation unit for sep-
aration of grease, which is then returned for 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 immed-
Baker, D. and White, T. "Treatment of Meat Packing Waste using PVC Trickling
Filters", National Symposium on Food Processing, Denver, March 23-26, 1971.
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WASTES FROM
KILL FLOOR
TRICKLING
FILTER NO. 2
TRICKLING
FILTER NO. I
AIR FLOTATION
TANK
PRE-AERATION
TANK
ANAEROBIC
LAGOON NO I
CHLORINE CONTACT
TANK
ANAEROBIC
LAGOON NO. 2
FIGURE NO. 6
FARMLAND FOODS
DENISON, IOWA
EFFLUENT
TO RIVER
-------
oxygen demand in preparation for discharge to the plastic media trickling
filters. These filters are normally used in series, with provisions for
parallel operation. The filter effluent 1s then clarified and disinfected
in a chlorine contact basin prior to discharge to the Boyer River. Sludge
is wasted back to the anaerobic lagoons.
The air flotation unit functions primarily to remove grease and was de-
signed with the following dimensions and performance criteria:
Hydraulic Loading 1500 gpm
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 pounds/day
Design Loading 15 pounds BOD/1000 ft.3
Depth 14 feet
Surface Area-- 1.97 acres
BOD Removal 80 percent
The preaeration basin serves to help reduce odors which may emanate from
the anaerobic effluent. Such odors would create serious problems due to the
close proximity of a residential area. The design engineers also hoped to
begin converting the effluent from the anaerobic lagoons to an aerobic state
prior to 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 cfm.
The trickling filters have shown the best results when they have been oper-
ated in series. The synthetic filter media is polyvinyl chloride (PVC) manu-
factured by B. F. Goodrich Co. This type of media may be loaded at higher
rates, is lighter in weight and is more uniform than standard rock media.
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The media is formed in 2 feet by 4 feet by 2 feet sections which are stacked
in layers of 11 cells, resulting in a total depth of 22 feet. Design data for
the filters is as follows:
BOD LOADING
First Stage 101 lbs/1000 ft3
Second Stage 31 lbs/1000 ft3
Hydraulic Loading 0.5 gpm/ft^
BOD Removal 91 percent
Diameter 39 feet
Media Depth 22 feet
The final clarifiers 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 utilized at Farmland Foods, each with a
surface overflow rate of 800 gpd/ft2.
The chlorine contact chamber was designed for a contact time of 49 minu-
tes and a chlorine dosage rate of 10 mg/1.
Table tfll shows the plant efficiencies, both for the total plant and on
a unit by unit basis.
TABLE VII
PLANT EFFICIENCIES*
PERCENT REMOVAL
FARMLAND FOODS
DENISON, IOWA
UNIT
Flotation
Anaerobic
Lagoons
Trickling
Filters
Chlorine
Total Plant
Removal
Excluding Flotation
*Baker and White
BOD
33
82
74
™
97.4
COD
11
68
73
"
91.5
GREASE
62
78
69
"
96.5
SS
32
59
80
•
93.5
COL I FORM
.
—
—
99+
99+
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The operating expenses for the year 1970 are given below in Table VIII.
When determined on a daily basis, the cost of operation was approximately $ 304
per day.
TABLE VIII
OPERATING EXPENSES
1970
Salaries - $ 47,893
Utilities 1,443
Maintenance 10,413
Capital Cost Debt Retirement 50,900
$ 110,648
D. IOWA BEEF PROCESSORS. INC.. DAKOTA CITY. NEBRASKA
The Dakota City, Nebraska, plant of Iowa Beef Processors, Inc., (IBP), lies
just outside of 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 suburtan area to the west.
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 Ibs. BOD per day and 28,000 Ibs. SS
per day. The average temperature of the waste coming from the combined slaughter-
ing and processing operations ranges between 90 degrees and 105 degrees 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 utilizing rotating biological discs following anaerobic treat-
ment had not been tried prior to development of the IBP Dakota City project. All
previous research and operational data had been in the area of domestic waste-
water, and it was necessary to establish independent data for the design. As
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a result, a pilot test program using the anaerobic effluent from one of IBP's
existing waste treatment facilities, was initiated to evaluate the rotating
biological discs. The pilot plant consisted of three stages of 4-foot ro-
tating discs, each capable of delivering 1750 gpm, with 50 discs 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 discs,
as well as 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 biolobical discs,
final clarifiers, and chlorination facilities, as shown on Figure 7. Iowa
Beef Processors, Inc., Dakota City, applied for and received a Federal demon-
stration grant to assist in the construction of the project.
The following design criteria was used in the design of the waste treat-
ment facilities:
Design BOD 33,600 Ibs/day
Design Average Flow- 3,000,000 gal/day
The lift station consists of three self-priming centrifugal pumps each
capable of delivering 1750 gpm. 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 1000 cubic
feet, and BOD removal averages approximately 85%.
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c
I
I
I
\
FORCE MAIN I
FROM LIFT |
STATION j
ANAEROBIC
LAGOON
(TYP)
\
ROTATING
BIOLOGICAL
DISC BUILDING
RETURN SLUDGE
xSLUDGE
SLUDGE
RETURN
BLDG.
FINAL
CLARIFIER
FINAL
CLARIFIER
h--CHLORINE CONTACT
CHAMBER
OUTFALL TO
MISSOURI RIVER
FIGURE NO 7
WASTE TREATMENT FACILITIES
IOWA BEEF PROCESSORS, INC.
DAKOTA CITY, NEBRASKA
-------
The wastewater then flows to the rotating biological discs, which are
housed in a timber pole building. The design hydraulic loading on the discs
is 4.8 gallons per day per square foot, resulting in a total required disc
area of 625,000 square feet. This area is supplied by 24 shafts of 139
discs each. The discs are 11 feet in diameter and have a surface area of
190 square feet each. The anticipated BOD reduction through the disc system
is approximately 70%.
Following treatment in the RBS units, the wastewater is discharged to
two fifty-five foot diameter clarifiers, each designed for a design average
flow of 1.5 mgd. Sludge from the clarifiers is returned to the anaerobic
lagoon.
The wastewater then flows to the chlorine contact basin, 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
ton 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 one and one-half years. Operation of the entire facility
including the rotating biological discs, 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 is
not available regarding treatment efficiencies. The anticipated overall BOD
removal through the facility is approximately 90-95%.
Total construction cost of the project including the lift station and
force main is approximately $814,000.00.
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E. LYKES BROTHERS PACKING PLANT. PLANT CITY INDUSTRIAL PARK. FLORIDA
The Lykes Brothers Packing Plant, is located in Florida, a state which
does not permit construction of anaerobic lagoons. Moreover, the site avail-
able for construction of waste treatment facilities was characterized by high
ground water and sandy soil, weighing heavily against any type of large lagoon.
The treatment system effluent was to be discharged into a dry ditch, so a high de-
gree of secondary treatment was required. After consideration of several different
treatment schemes, the design engineers concluded that the extended aeration
modification of the activated sludge process would best meet 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 prior
to commencement of design, in order to minimize the hydraulic and organic load-
ing on the treatment system. The final design criteria, based on 6 pounds of
BODjj and 900 gallons per head, was as follows:
Total Daily Flow 315,000 gallons per day
Total BODg 2,100 pounds per day
The treatment system consists of a grease skimming and sedimentation tank,
two extended aeration tanks, final clarifier, polishing lagoon, aerobic di-
gester and sludge drying beds. The flow diagram is shown in Figure No. 8.
The settling-grease skimming basin is sized for thirty 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 1000 cubic feet of tank volume.
The two tanks have a total volume of 105,000 cubic feet, and on the basis of
the design flow, provide a retention period of 30 hours. Air is supplied to
-57-
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GREASE HOLD
TO TANK TRUCK
I'LANT ETF-LUFNT
L
BAR
SCREEN
STABILIZATION
POND
AIR
FACILITY
FROTH SPRAY \
PUMPS s~\ \
O
) FROTH SPRAY
LINE
tr
LJ
o
UJ
o
LJ
I-
X
LJ
^/SETTLING
TANK
QC
UJ
Q
UJ
Q
Z
LJ
X
'UJ
I-
LJ
5
o
OD
O
tr
I
SI UPGE DRYING BEDS
TU OPEN DITCH 5 TURKEY CRECK
CHLORINATION
FIGURE NO 8
LYKES BROTHERS PACKING PLANT
PLANT CITY, FLORIDA
-------
the aeration tanks at the rate of 1500 cubic feet per day per pound of applied
BOD. Sludge is wasted periodically to the aerobic digester.
The final settling tank is designed for a surface overflow rate of 800
gallons per day per square ft. Settled sludge is returned at a rate of 540
gpm by an air lift pump to the head of the aeration tank or to the aerobic di-
gester.
Effluent from the settling tank flows into a five-acre stabilization pond,
which serves to provide tertiary treatment prior to 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/1 minimum chlorine residual.
The aerobic digester has a volume of 37,200 cubic feet. Air is introduced
into the digester at the rate of 350 cfm 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
is given in Table IX.
TABLE IX
WASTEWATER ANALYSIS - LYKES BROTHERS PACKING PLANT
(Average Values from Past 6 Months)
ITEM
PH
BOD
Total Solids
Suspended Solids
Dissolved Oxygen
Chlorides*
RAW
6.9
1,574.0
5,507
396
0.0
1,787
EFFLUENT
FROM FINAL
SETTLING TANK
7.4
89.0
3,621
180
0.80
1,700
CONCENTRATIONS
(mg/1)
EFFLUENT FROM POND
7.4
15.7
2,884
56
4.40
1,425
This sampling data is based upon an average water usage of 240,000 gallons
per day.
*Approximately one ton of salt is used every two weeks for plant process.
-58-
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Total construction cost of the project in 1966 was approximately $ 250,000.00.
Operational and maintenance costs as reported by plant personnel, are approxi-
mately $20,000.00 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 the January 1968 Journal of the Mater Pollution Control
Federation.
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SECTION VIII
SURVEY OF EXISTING WASTE TREATMENT FACILITIES
FOR THE MEAT PROCESSING INDUSTRY"
Questionnaires were sent to all fifty 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, twenty-five states have responded to the
questionnaire. Several of the states indicated the existence of few meat pro-
cessing 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 practiced. Ponds which had only seepage as effluent were also noted
•in some localities, notably in the western United States where the weather is
arid. These treatment facilities apparently were meeting state standards be-
cause of subsurface discharge or no effluent discharge.
Questionnaires returned from states where more and larger meat processing
operations were located showed that more complex methods of treatment were em-
ployed. It is interesting to note, however, that the regulatory agencies from
these states felt that only half the treatment facilities under their juris-
diction 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 re-
ported as working well in achieving good BOD reduction. Values reported were
in excess of 90% BOD removal, generally over 95%. Extended aeration systems
-60-
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also showed high BOD removals, in the range of 90%. There seemed to be a
tendency to use extended aeration on smaller plants with the lagoons being
employed on large installations, (i.e. greater than 500,000 gpd). Less fre-
quently used systems were aerated lagoons or oxidation ponds. Spray irri-
gation was used as a means of disposal, particularly in arid climates. Use
of trickling filters, based on the limited data, was not wide spread. Such
installations are in existence, of course, and are capable of providing good
treatment if properly loaded and operated.
Table X lists the types and number of waste treatment facilities reported
by the twenty-six states responding to the questionnaire.
TABLE X
EXISTING WASTE TREATMENT FACILITIES FOR
THE MEAT PROCESSING INDUSTRY*
NUMBER OF
TREATMENT INSTALLATIONS SIZE RANGE
Anaerobic-
Aerobic Lagoons
Anaerobic-
Aerated Lagoons
Aerated Lagoons
Aerobic Lagoons
Lagoons
Extended Aeration
Activated Sludge
Trickling Filters
Spray Irrigation
Septic Tanks
Other
None
26
6
11
30
21
3
7
2
33
14
2
0.40-2.50 mgd
0.66-1.97 mgd
0.005-0.75 mgd
0.005-1.20 mgd
.001-0.10 mgd
0.060 mgd
1.0-1.85 mgd
-
0.01 - 1.15 mqd
-
-
BOD REDUCTIONS
90-99%
98-99%
91-98%
87-99%
85-9921
qq«
92-9q*
-
-
-
-
The above table is general in nature; in many cases the treatment scheme
has been simplified for use in this table. For example, if a system consisted
of grease removal, primary screening, flow equalization, extended aeration and
*Based on results of a questionnaire distributed to State Water Pollution Control
Agencies. Data received from the following states: 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.
-61-
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chlorination, the overall system was classified as extended aeration. Flow and
performance data was 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 1000 head/day and had a BOD of 2250
mg/1. However, the report went on to state that a program is underway to pro-
vide treatment.
-62-
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APPENDIX
-------
AMERICAN BEEF PACKERS
COUNCIL BLUFFS, IOWA
A-l SOLIDS SCREENING FACILITY AND HIDE PROCESSING SETTLING TANK
-------
AMERICAN BEEF PACKERS
COUNCIL BLUFFS, IOWA
A-2 HIDE SETTLING TANK
-------
AMERICAN BEEF PACKERS
COUNCIL BLUFFS, IOWA
A-3 GREASE FLOTATION TANK
-------
AMERICAN BEEF PACKERS
COUNCIL BLUFFS, IOWA
A-4 FINAL CLARIFIER
-------
AMERICAN BEEF PACKERS
COUNCIL BLUFFS, IOWA
A-5 AERATION BASIN
-------
IOWA BEEF PROCESSORS, INC.
DENISON, IOWA
A-6 MEAT PROCESSING PLANT AND LAGOON LAYOUT
-------
IOWA BEEF PROCESSORS, INC.
DENISON, IOWA
.,•—--
v
A-7 ANAEROBIC LAGOON
-------
IOWA BEEF PROCESSORS, INC.
DENISON, IOWA
A-8 AEROBIC LAGOON
-------
FARMLAND FOODS
DENISON, IOWA
A-9 ANAEROBIC LAGOON
-------
FARMLAND FOODS
DENISON, IOWA
A-10 PRE-AERATION BASIN, TRICKLING FILTERS AND CONTROL BUILDING
-------
FARMLAND FOODS
DENISON, IOWA
A-ll TRICKLING FILTER ARMS AND MEDIA
-------
FARMLAND FOODS
DENISON. IOWA
A-12 FINAL CLARIFIER
-------
FARMLAND FOODS
DENISON, IOWA
A-13 CHLORINE CONTACT TANK
-------
FARMLAND FOODS
DENISON, IOWA
A-14 TREATED EFFLUENT
-------
IOWA BEEF PROCESSORS, INC.
DAKOTA CITY, NEBRASKA
A-15 ANAEROBIC LAGOON
-------
IOWA BEEF PROCESSORS, INC.
DAKOTA CITY, NEBRASKA
A-16 ROTATING BIOLOGICAL DISC BUILDING
-------
IOWA BEEF PROCESSORS, INC.
DAKOTA CITY, NEBRASKA
A-17 ROTATING BIOLOGICAL DISCS
-------
IOWA BEEF PROCESSORS, INC.
DAKOTA CITY, NEBRASKA
A-18 FINAL CLARIFIER
-------
IOWA BEEF PROCESSORS, INC.
DAKOTA CITY, NEBRASKA
A-19 CHLORINE CONTACT TANK
-------
LYKES BROTHERS
PLANT CITY, FLORIDA
A-20 AERATION BASIN
-------
LYKES BROTHERS
PLANT CITY, FLORIDA
A-21 FINAL CLARIFIER
-------
LYKES BROTHERS
PLANT CITY, FLORIDA
A-22 POLISHING LAGOON
-------
A-23 TRAVELING SPRINKLER SYSTEM
-------
A-24 TRAVELING SPRINKLER SYSTEM
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PAGE NOT
AVAILABLE
DIGITALLY
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