Development Document for
Proposed Effluent Limitations Guidelines
and New Source Performance Standards
for the
PROCESSOR
Segment of the
MEAT PRODUCTS
Point Source Category
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
AUGUST 1974
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DEVELOPMENT DOCUMENT
for
PROPOSED EFFLUENT LIMITATIONS GUIDELINES
and
NEW SOURCE PERFORMANCE STANDARDS
for the
PROCESSOR
SEGMENT OF THE
MEAT PRODUCTS POINT SOURCE CATEGORY
Russell E. Train
Administrator
James L. Agee
Assistant Administrator for Water and
Hazardous Materials
Allen Cywin
Director, Effluent Guidelines Division
Jeffery D. Denit
Project Officer
August, 1974
Effluent Guidelines Division
Office of Water and Hazardous Materials
U. S. Environmental Protection Agency
Washington, D. C. 20460
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ABSTRACT
This document presents the findings of an extensive study of the
meat processing industry by the Environmental Protection Agency
for the purpose of developing effluent limitations guidelines and
Federal standards of performance for the industry, to implement
Sections 304 and 306 of the Federal Water Pollution Control Act
amendments of 1972 (the "Act").
The meat processing plants included in the study were those
plants that manufacture prepared meats and meat products from
purchased carcasses, meat cuts, and other materials, but that do
no slaughtering on the same plant site. Processing plants that
produce 2730 kg (6000 Ib) of finished product per day, or less,
are categorized as small processors; the rest of the industry,
the large processors, includes four subcategories. The
distinction between large and small affects the implementation
proposed to meet the recommended limitations.
Effluent limitations are set forth for the degree of effluent
reduction attainable through the application of the "Best
Practicable Control Technology Currently Available," and the
"Best Available Technology Economically Achievable," which must
be achieved by existing point sources by July 1, 1977, and July
1, 1983, respectively. The "Standards of Performance for New
sources" set forth the degree of effluent reduction which is
achievable through the application of the best available
demonstrated control technology, processes, operating methods, or
other alternatives. The proposed recommendations require the
best secondary treatment technology currently available for
discharge into navigable water bodies by July 1, 1977, and for
new source performance standards. This technology is represented
by chlorination added to a wide variety of waste treatment
practices currently in use by the industry; e.g., septic tanks
with subsoil seepage for small processors which do not require
chlorination; and aerated lagoon systems, activated sludge, and
extended aeration for large processors, with about $2.5 million
in capital expenditures required by the industry. The
recommendations for July 1, 1983, are for the best secondary
treatment and in-plant control, as represented for large
processors by reduced in-plant water use, air flotation with pH
control and flocculant addition, and a final sand or mixed media
filter in addition to the waste treatment systems in use at the
present time. Ammonia removal will also be required if the
effluent exceeds the limitation. When sufficient suitable land
is available, land disposal via irrigation with no discharge may
be the most economical option.
Supportive data and rationale for development of the proposed
effluent limitations and standards of performance are contained
in this report.
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CONTENTS
Section
I. CONCLUSIONS 1
II. RECOMMENDATIONS 3
III. INTRODUCTION 5
Purpose and'Authority 5
Summary of Methods Used for Development of the
Effluent Limitations Guidelines and Standards
of Performance 6
General Description of the Industry 8
General Process Description 10
Manufacturing Operations 13
Storage, Shipping and Receiving 16
Raw Material Thawing 17
Carcass/Meat Handling and Preparation 18
Seasonings, Spices and Sauce Preparation 19
Weighing and Batching 20
Grinding, Mixing and Emulsifying 21
Extrusion, Stuffing and Molding 22
Linking 23
Pickle Application/Injection 23
Cooking, Smoking and Cooling 24
Casing Peeling 25
Product Holding/Aging 26
Bacon Pressing and Slicing 26
Can Preparation, Filling and Covering 27
Retorting 28
Packaging 28
Materials Recovery 29
Production Classification 30
Anticipated Industry Growth 31
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CONTENTS (Continued)
Section Page
IV. INDUSTRY CATEGORIZATION 33
Categorization 33
Rationale for Categorization 36
Waste Water Characteristics and Treatability 36
Finished Production Mix 37
Manufacturing Operations 38
Raw Materials 41
Plant Size 41
Age and Location 44
V. WATER USE AND WASTE CHARACTERIZATION 45
Waste Water Characteristics 45
Raw Waste characteristics 45
Discussion of Raw Wastes 52
Process Waste Water Flow Diagrams 54
Water Use. - Waste Load Relationships 58
Sources of Waste Water and Waste Load 60
Meat Materials Preparation 60
Pickling 61
Product Cooking and Cooling 62
Canning 63
VI. SELECTION OF POLLUTANT PARAMETERS 67
Selected Parameters 67
Rationale for Selection of Identified Parameters 67
5-Day Biochemical Oxygen Demand 67
Chemical Oxygen Demand 69
Suspended Solids 69
Total Dissolved Solids 71
Grease 71
Total Volatile Solids 72
Ammonia Nitrogen 72
Kjeldahl Nitrogen 74
Nitrates and Nitrites 74
Phosphorus 74
Temperature 76
Fecal Collform 76
pH 78
Others 79
tv
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CONTENTS (Continued)
Section
VII. CONTROL AND TREATMENT TECHNOLOGY 81
Summary 81
In-Plant Control Techniques 83
Pickling and Curing Solutions 83
Water Conservation Practices 83
Cleanup Operations 84
In-Plant Primary Treatment 84
Flow Equalization 84
Screens 85
Catch Basins 87
Dissolved Air Flotation 88
Waste Water Treatment Systems 92
Anaerobic Processes 93
Aerated Lagoons 96
Aerobic Lagoons 96
Activated Sludge 98
Trickling Filter 101
Rotating Biological Contactor 102
Performance of Various Secondary Treatment
Systems 103
Tertiary and Advanced Treatment 105
Chemical Precipitation of Phosphorus 105
Sand Filter .107
Microscreen-Microstrainer 109
Nitrification-Denitrification 110
Ammonia Stripping 113
Spray/Flood Irrigation 115
Ion Exchange 117
VIII. COST, ENERGY, AND NONWATER QUALITY ASPECTS 121
Summary 121
"Typical" Plant 126
Waste Treatment Systems 127
Treatment and Control Costs 128
In-Plant Control Costs 128
Investment Costs Assumptions 131
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CONTENTS (Continued)
Section Page
Annual Costs Assumptions 136
Energy Requirements 137
VIII. COST, ENERGY, AND NONWATER QUALITY ASPECTS
(Continued)
Nonwater Pollution by Waste Treatment Systems 137
Solid Wastes 137
Air Pollution 139
Noise 139
IX. EFFLUENT REDUCTION ATTAINABLE THROUGH THE
APPLICATION OF THE BEST PRACTICABLE CONTROL
TECHNOLOGY CURRENTLY AVAILABLE—EFFLUENT
LIMITATIONS GUIDELINES 141
Introduction 141
Effluent Reduction Attainable Through the
Application of Best Practicable Control Technology
Currently Available 142
Identification of Best Practicable Control
Technology Currently Available 142
Rationale for the Selection of Best Practicable
Control Technology Currently Available 144
Age and Size of Equipment and Facilities 144
Total Cost of Application 145
Engineering Aspects of Control Technique
Applications 145
Process changes 148
Nonwater Quality Environmental Impact 148
X. EFFLUENT REDUCTION ATTAINABLE THROUGH THE
APPLICATION OF THE BEST AVAILABLE TECHNOLOGY
ECONOMICALLY ACHIEVABLE—EFFLUENT LIMITATIONS
GUIDELINES 149
Introduction 149
Effluent Reduction Attainable Through Application
of the Best Available Technology Economically
Achievable 151
Identification of the Best Available Technology
Economically Achievable 151
VI
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CONTENTS (Continued)
Section
Rationale for Selection of the Best Available
Technology Economically Achievable 153
Age of Equipment and Facilities 153
Total Cost of Application in Relation to
Effluent Reduction Benefits 153
Engineering Aspects of Control Technique
Application 153
Process Changes 154
Nonwater Quality Impact 154
XI. NEW SOURCE PERFORMANCE STANDARDS 155
Introduction 155
Effluent Reduction Attainable for New Sources 155
Identification of New Source Control Technology 156
Pretreatment Requirements 157
XII „ ACKNOWLEDGMENTS 159
XIII. REFERENCES 161
XIV. GLOSSARY 165
vn.
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FIGURES
Number
1 General Process for Meat Cuts and Portion Control
Products 11
2 General Process for Hams and Bacon 12
3 General Process for Comminuted Meat Products 14
4 General Process for Canned Meat Products 15
5 Subcategories in the Meat Processing Industry 35
6 Raw Waste Load Variations by Subcategory 42
7 Process Waste Water Flow—Cut Meats and Comminuted
Meats 55
8 Process Waste Water Flow—Hams and Bacon 56
9 Process Waste Water Flow—Canned Meats 57
10 Raw Waste Load Variation with Flow 59
11 Suggested Meat Processor Waste Reduction
Program 82
12 Dissolved Air Flotation 89
13 Process Alternatives for Dissolved Air Flotation 90
14 Anaerobic contact Process 95
15 Activated Sludge Process 99
16 Chemical Precipitation 105
17 Sand Filter System 107
18 Microscreen/Microstrainer 109
19 Nitrification/Denitrification 111
20 Ammonia Stripping 113
21 Spray/Flood Irrigation System 115
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FIGURES (Continued)
Number
22 Ion Exchange
gage
119
23 Waste Treatment Cost Effectiveness at Flow of 38,000
Liters/Day (10,000 GPt>) 133
24 Waste Treatment Cost Effectiveness at Flow of 380,000
Liters/Day (100,000 GPD) 134
25 Waste Treatment Cost Effectiveness at Flow of 908,000
Liters/Day (240,000 GPD) 135
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TABLES
Number
1 Meat Processing Industry Production, Waste Water
Volume, and Raw Waste Load by Subcategory 39
2 Number of Plants in Each Subcategory with Indicated
Raw Waste Load 40
3 Plant Size Distribution of Meat Processing Plants
That Returned Survey Questionnaire 43
U Raw Waste Characteristics of Small Processors 47
5 Raw Waste Characteristics of Meat Cutter Subcategory 49
6 Raw Waste Characteristics of Sausage and Luncheon
Meats Processor Subcategory 50
7 Raw Waste Characteristics of Ham Processor Subcategory 51
8 Raw Waste Characteristics of Meat Canner Subcategory 53
9 Performance of Various Secondary Treatment Systems 104
10 Additional Investment Cost for the "Typical" Plant in
Each Subcategory to Achieve Indicated Standards 122
11 Addition to the Total Annual Cost and Operating Cost
for a Plant in Each Subcategory to Operate Treatment
System as Described 123
12 Additions to the Annual Cost and Operating Cost Per
Unit of Production for a Plant in Each Subcategory
to Operate Treatment System as Described 125
13 Operating Parameters for "Typical" Plants 128
14 Waste Treatment Systems, Their Use and Effectiveness 129
15 Secondary Treatment by Each Subcategory 130
16 In-Plant control Equipment Cost Estimates 131
17 Sludge Volume Generation by Waste Treatment System 138
18 Recommended Effluent Limitations for July 1, 1977 143
19 Recommended Effluent Limitations for July 1, 1983 150
20 Capital Investment, Operating and Total Annual Costs
for New Point Sources 157
21 Conversion Table 173
xi
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SECTION I
CONCLUSIONS
The study presented herein is a part of an overall investigation
of the meat processing (no slaughtering of animals accomplished
in the plants) and rendering (accomplished independent of
slaughterhouses, packinghouses, and poultry processors) industry
segments of the meat products point source category.
Because of evidence developed early in the investigation, it
became apparent that meat processing operations differed
materially from rendering operations as to raw materials,
processes, products and other factors. As a result, an initial
categorization which split the two industry segments was utilized
to facilitate a thorough analysis with a separate study report
for each. For a parallel technical report on rendering, the
reader is refered to the, "Development Document for Proposed
Effluent Limitations Guidelines and New Source Performance
Standards for the Renderer Segment of the Meat Product and
Rendering Point Source Category." (June 1974).
A conclusion of this study is that the meat processing industry
comprises five subcategories:
Small processor
Meat cutter
Sausage and luncheon meats processor
Ham processor
Meat canner
The primary criterion for the establishment of the categories was
the _5-day biochemical oxygen demand (BOD5) in the plant waste
water in relation to the nature of finished products as discussed
in Section IV. Other criteria were plant size and type of
product manufactured in the plant. Information relating to other
pollutants and the effects of such parameters as age and location
of plants, type of raw material, production processes, and
treatability of wastes all lent support to the categorization
decision.
The wastes from all subcategories are amenable to biological
treatment processes, and no materials harmful to municipal waste
treatment processes were found.
Discharge limits, representing the average of the best treatment
systems in the industry for the five subcategories and transfer
of technology from meat packing plants, are being met by 100
percent of the small processors and by 80 percent of the large
processing plants for which data are available, except for the
fecal coliform limit. These limits plus a fecal coliform limit
are recommended for 1977. The same limits are recommended for
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new sources. It is estimated that there will be about $2.5
million in capital costs required to achieve the 1977 limits by
the industry.
For 1983, effluent limits were determined as the best achievable
in the industry for BODS and suspended solids. Limits for
Kjeldahl nitrogen, ammonia, nitrites and nitrates, and phosphorus
were established on the basis of transfer of technology from
other industries or of newly developing technology. It is also
concluded that, where suitable and adequate land is available,
land disposal is a more economical option.
It is estimated that the cost to achieve the 1983 limits by the
large processor group within the industry will be between $35 and
$60 million. These costs represent between 10 and 18 percent of
the total capital expenditures estimated to have been spent by
the large processors over the last ten years.
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SECTION II
R ECOMMENDATIONS
Limitations recommendations for discharge to navigable waters by
large processors for July 1, 1977, are based on the
characteristics of well-operated secondary treatment plants. The
limitations for 5-day biochemical oxygen demand (BOD5) range, for
example, from 0.015 kg/kkg finished product (FP) for meat cutters
to 0.33 kg/kkg FP for meat canning plants.
The limitations recommendation for 1977 and 1983 for smal1
processors is no allowable discharge. This is already the level
of pollution control being accomplished by all plants in this
subcategory for which data were available, that are not connected
to municipal sewers.
Recommended New Source Standards are the same as the 1977
limitations.
Limitations recommended for large processors for 1983 are
considerably more stringent. For example, BOD5 limits range from
0.009 kg/kkg FP for meat cutters to 0.17 kg/kkg FP for a meat
canner. Limits are also placed on the other parameters mentioned
above, with particular attention to the ammonia discharge. The
suspended solids range from 0.012 to 0.22 kg/kkg FP; grease is
set at the levels commensurate with current materials recovery
practiced by plants coincident with biological treatment and
falls within the limits of detection by standard analytical
methods; ammonia and phosphorus, are limited by the
concentrations achievable by the technology, rather than by a
relation to the production level. In cases where suitable and
adequate land is available, land disposal (no discharge) will be
a practical option.
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SECTION III
INTRODUCTION
PURPOSE AND AUTHORITY
Section 301(b) of the Federal Water Pollution Control Act
Amendments of 1972 (the Act) requires the achievment by not later
than July 1, 1977, of effluent limitations for point sources,
other than publicly owned treatment works, which are based on the
application of the best practicable control technology currently
available as defined by the Administrator pursuant to Section
304(b) of the Act. Section 301 (b) also requires the achievement
by not later than July 1, 1983, of effluent limitations for point
sources, other than publicly owned treatment works, which are
based on the application of the best available technology
economically achievable which will result in reasonable further
progress toward the national goal of eliminating the discharge of
all pollutants, as determined in accordance with regulations
issued by the Administrator pursuant to Section 304(b) of the
Act. Section 306 of the Act requires the achievement by new
sources of a Federal standard of performance providing for the
control of the discharge of pollutants which reflects the
greatest degree of effluent reduction which the Administrator
determines to be achievable through the application of the best
available demonstrated control technology, processes, operating
methods, or other alternatives, including, where practicable, a
standard permitting no discharge of pollutants.
Section 304(b) of the Act requires the Administrator to publish
within one year of enactment of the Act, regulations providing
guidelines for effluent limitations setting forth the degree of
effluent reduction attainable through the application of the best
practicable control technology currently available and the degree
of effluent reduction attainable through the application of the
best control measures and practices achievable, including
treatment techniques, processes, and procedure innovations,
operation methods and other alternatives. The regulations
proposed herein set forth effluent limitations guidelines
pursuant to Section 304(b) of the Act for the meat processing
plant subcategory within the meat products source category.
Section 306 of the Act requires the Administrator, within one
year after a category of sources is included in a list published
pursuant to Section 306 (b) (1) (A) of the Act, to propose
regulations establishing Federal standards of performance for new
sources within such categories. The Administrator published in
the Federal Register of January 16, 1973 (38 F.R. 1624), a list
of 27 source categories. Publication of the list constituted
announcement of the Administrator•s intention of establishing,
under Section 306, standards of performance applicable to new
sources for the meat processing plant subcategory within the meat
products source category, which was included in the list
published January 15, 1973.
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SUMMARY OF METHODS USED FOR DEVELOPMENT OF THE EFFLUENT
LIMITATIONS GUIDELINES AND STANDARDS OF PERFORMANCE
The effluent limitations guidelines and standards of performance
proposed herein were developed in the following manner. >The
point source category was first studied for the purpose of
determining whether separate limitations and standards are
appropriate for different segments within the point source
category. This analysis included a determination of whether
differences in raw material used, product produced, manufacturing
process used, age, size, waste water constituents, and other
factors required development of separate effluent limitations and
standards for different segments of the point source category.
The raw waste characteristics for each segment were identified.
This included an analysis of (1) the source and volume of water
used in plants and the source of waste and waste waters in these
plants; and (2) the pollutant constituents (including thermal) of
all waste waters such as BOD5, COD, suspended solids, and grease
which result in taste, odor, or color effects in water or aquatic
organisms. The constituents of the waste waters which should be
subject to effluent limitations and standards of performance were
identified.
The full range of control and treatment technologies existing
within each sufccategory was identified. Each distinct control
and treatment technology was identified including the influent
quantity of waste constituents (including thermal), the chemical,
physical, and biological characteristics of the pollutants, and
the effluent quality resulting from the application of each of
the technologies. The problems, limitatons, and reliability of
each treatment and control technology and the required
implementation time were also identified. In addition, the
nonwater-quality environmental impact of the application of such
technologies and the generation of air pollution, solid waste,
noise, and other pollution problems were also identified. The
energy requirement of each of the control and treatment
technologies was identified as well as the economic cost of the
application of such technologies.
The information, as outlined above, was then evaluated in order
to determine what levels of technology constituted the "best
practicable control technology currently available,11 "best
available technology economically achievable" and the "best
available demonstrated control technology, processes, operating
methods, or other alternatives." In identifying such
technologies, various factors were considered. These included
the total cost of application of technology in relation to the
effluent reduction benefits to be achieved from such application,
the age of equipment and facilities involved, the manufacturing
process and practices employed, the engineering aspects of the
application of various types of control techniques, process
changes, nonwater-quality environmental impact (including energy
requirements), and other factors.
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The data used to describe and analyze the meat processing
industry were derived from a number of sources. These sources
included Refuse Act Permit Program data; EPA research
information; data from various state and city agencies with waste
water disposal responsibility; data and information from North
Star files and reports; a voluntary questionnaire issued through
the American Association of Meat Processors (AAMP), formerly the
National Institute of Locker and Freezer Provisioners, the
American Meat Institute (AMI), the National Independent Meat
Packers Association (NIMPA), and Western States Meat Packers
Association (WSMPA); qualified technical consultation; and on-
site visits, interviews, and waste water sampling at several meat
processing plants in various areas of the United states. All
references used in developing the guidelines for effluent
limitations and standards of performance for new sources are
included in Section XIII of this document.
The North Star industry survey questionnaire provided about 95
percent of the raw data used to categorize the industry, to
characterize the raw waste, and to determine the extent and
effectiveness of the use of various treatment systems. A total
of some 143 plants represented the raw data base, for which
production data were available for all 143, waste water flow data
for 91, and raw BOD5 load for 38 of the plants. Information from
the USDA was primarily product and production data. The data from
the Refuse Act Permit Program were of very limited value; they
were used primarily to verify the types of treatment used by
various plants and to assist in selecting the pollutant
parameters listed in Section VI. Data were obtained for 148
identifiable plants and used for categorization and raw waste
characterization. The other sources, including site visits and
interviews, were used to fill in the information gaps and to
provide additional insight and understanding to develop the
rationale in categorization.
The data were coded and stored in a computer for analysis in
categorizing the industry and characterizing the raw wastes of
each subcategory. Seventy-seven variables were available to
describe each plant. The variables were listed in either numeric
or nonnumeric form to accommodate the type of input information
available. The numeric data included daily production figures,
water quantities, working day and week, measures of 14 waste
water parameters in raw and treated effluent, and frequency of
plant and equipment cleanup. The nonnumeric data covered the
data source, type of plant inspection, product line, processes in
use in the plant and method of disposal of waste from each
process, type of primary, secondary, and tertiary treatment of
waste water, and method of disposal of waste water. Missing data
were coded as such.
Observation of meat processing industrial practices led to the
consideration and subsequent analysis of those variables that
influence raw waste load. The representative parameter of the
raw waste load was selected as BOD5, measured by kg (Ib) of BOD5
in the primary treatment effluent per kkg (1000 Ib) of finished
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product (FP). Correlation analysis, cross tabulation, and linear
regression were used with the computer to reduce the
categorization variables under consideration to plant size, water
use, and product mix.
Within the sample of plants responding to the questionnaire,
there is a preponderance of plants producing less than 2730 kg
(6000 Ib) of finished product per day. The rest of the industry
sample covers the spectrum from about 3400 to 230,000 kg (7500 to
500,000 Ib) of finished product per day. The former group of
"small" plants was found to generate comparatively small
quantities of waste water, averaging about 3200 liters (840 gal.)
per day which is in sharp contrast to the other group of plants
that averages 443,000 liters (117,000 gal.) per day. This
enables the small meat processors to treat the waste water and
dispose of it through septic tanks and subsoil seepage systems,
thereby achieving no discharge of waste water. Because the small
processors typically generate these small quantities of waste
water, which are amenable to this type of disposal, treatability
of wastes in a unique manner is applicable as a basis for
categorization as small processors, in addition to the primary
categorization criterion of size.
Among those plants that produce more than 2730 kg (6000 Ib) per
day, the normalized raw waste loading was found to be fairly
widespread. Product mix appeared to be the remaining possibility
for the rationalization of additional subcategories among the
large plants in the meat processing industry.
Observation of industry practice and analysis of the data led to
the identification of specific products as categorization bases
rather than specific product mixes. The product bases were found
to be the production of cut products only; any processed products
with no ham or canned products; any product mix with ham
production, but no canning; and canned meat products with or
without other processed meat products. These bases for
categorization yielded statistically separable and unique raw
waste load distributions and yielded to explanation and
justification based on production and cleanup processes and
practices.
GENERAL DESCRIPTION OF THE INDUSTRY
Meat processing plants purchase animal carcasses, meat parts, and
other materials and manufacture sausages, cooked meats, cured
meats, smoked meats, canned meats, frozen and fresh meat cuts,
natural sausage casings, and other prepared meats and meat
specialities. None of the plants in this industry engages in any
slaughtering on the same premises with the processing activity.
These plants are all classified under industry No. 2013 in the
Office of Management and Budget, Standard Industrial
Classification Manual.
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The product mix of plants in this industry includes virtually
every possible combination of products. There are plants that
specialize in one or two types of processed meat products, such
as hams, fresh sausage, canned meat products, or meat cuts, and
plants that produce a number of products up to the full line of
processed meat products. This variation in product line occurs
in plants independent of the plant size.
There were 1374 meat processing establishments reported in the
1967 Census of Manufacturers in the U.S.2 The USDA Animal and
Plant Health Inspection Service reported 3465 "meat only" and
"meat and poultry" processing plants under Federal inspection as
of June 30, 1973.3 An additional 168 meat processing plants were
reported to be under Talmadge-Aiken inspection as of June 30,
1973. The meat processing industry had shipments totalling about
$4 billion in 1972. Shipments are expected to be eight percent
higher in 1974 than in 1973; this is two percent higher than
recent rates of six percent growth per year.*
The small plant in the meat processing industry, which by
definition in this study produces 2730 kg (6000 Ib) or less of
finished product per day, is estimated to account for 85 to 90
percent of the total number of plants. However, that segment of
the industry produces only 10 to 15 percent of the total meat
processing output. These estimates are based on information from
the North Star survey questionnaire and the assumption that the
profile of the meat processing industry is similar to the meat
packing industry in regard to the higher percentage of small
packers, based on number of plants, and their small output
compared to that of the rest oif the industry.
Data on waste loads and the extent of use of municipal waste
water treatment systems are not readily available. Regarding the
municipal systems, the FWPCA estimated that, in 1966, about 70
percent of all waste water from the meat packing and processing
industry went into municipal systems; and that by 1972, 80
percent of the plants would discharge to municipal systems.s The
North Star survey questionnaire data indicate that 90 percent of
the meat processing plants discharge to municipal systems.
Slab and sliced bacon, hams (not including canned hams), franks
and wieners, and smoked or cooked luncheon meats each accounted
for more than ten percent of the quantity of processed meat
products shipped in 1963 and 1967. Canned meat products had the
greatest increase in percentage of the industry's output, rising
from 6.8 percent in 1963 to 9.2 percent in 1967.z
The industry has plants throughout the country. However, the
middleAtlantic and North Central regions of the country produced
over 50 percent of the $3 billion in shipments by the industry in
1967. Illinois, with $450 million, had the highest value of
shipments of processed meat products in 1967, followed closely by
California and New York, with $386 and $376 million,
respectively. Pennsylvania and Massachusetts ranked fourth and
fifth with $244 and $221 million in shipments. Michigan, New
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Jersey, Ohio, and Texas completed the list of states with more
than $100 million of shipments in 1967.«
The ranking of states by number of federally inspected meat
processing plants as of June 30f 1973, was fairly comparable to
the above, with Pennsylvania first with 401 plants, followed by
New York, 329 plants; Illinois, 228; California, 223; and
Missouri with 177 plants. Massachusetts, Texas, New Jersey,
Kentucky, Minnesota, and Washington also have at least 100
federally inspected meat processing plants each.3
Three significant developments in the meat processing industry
relating to waste water generation, are the greater demand for
portion-controlled meats by hotels, restaurants, fast-food
outlets, and institutions; the use of high volume automated meat
processing equipment; and the question of possibly continuing use
of certain chemicals such as nitrites in curing solutions.
Waste waters from the production of processed meat products and
the associated facilities, operations, and plant or equipment
cleanup contain organic matter (including grease), suspended
solids, and inorganic materials such as phosphates and salts.
These materials enter the waste stream as meat and fat particles,
meat extracts and juices, curing and pickling solutions, and
caustic or alkaline detergents.
GENERAL PROCESS DESCRIPTION
The production of processed meat products is carried out in the
four general processes presented in Figures 1 through 4. Each
generalized process incorporates some operations common to the
others; however, each is sufficiently distinctive to merit
separate consideration. The differences in use and arrangement
of the processing operations relates directly to the type of
product produced in each process. The figures represent
generalized processes with major processing alternatives
included. Specific plant practices may differ somewhat in the
order or use of processing operations.
Meat cuts and portion-controlled products are typically prepared
for hotels, restaurants, institutions, and fast-food outlets.
The products range from the standard steaks, chops, and roasts to
portion-controlled hamburgers and minute steaks. The general
process for production of these products is presented in Figure
1.
The production of hams and bacon, depicted in Figure 2, involves
the preparation of the raw material for the injection or
application of a pickle solution followed by cooking and smoking.
The products are then cooled, aged if desired, sliced or
otherwise prepared for packaging, and packaged for storage and
shipment.
10
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ANIMAL
CARCASSES
FINISHED PRODUCT
PREPARATION
RECEIVING AND
STORAGE
BREAKING,
TRIMMING
BONING,
CUTTING
PACKAGING
I
THAWING
GRINDING,
MIXING
PRODUCT
FORMING
FINISHED PRODUCT
STORAGE,
SHIPPING
Figure 1. General Process for Meat Cuts and Portion Control Products
11
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HAMS
PORK BELLIES
RECEIVING AND
STORAGE
_L
FROZEN MATLS.
UNFROZEN
MAT'LS.
SEASONING, SPICES.
CHEMICALS
WATER
PICKLE SOLUTION
PREPARATION
THAWING IN
WATER
TEMPER IN
WATER
SKINNING, TRIMMING,
BONING
PICKLE APPLICATION,)
INJECTION
HOLDING
COOKING,
SMOKING
COOLING,
HOLDING
PACKAGING
FINISHED PRODUCT
STORAGE, SHIPPING
THAWING IN
AIR
BACON PRESS
SLICING
Figure 2. General Process for Hams and Bacon
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Comminuted meat products include those products that require
substantial size reduction, intensive mixing, and usually the
molding or forming of the finished product in a casing or
container, which may or may not be part of the finished product.
Figure 3 depicts the typical process steps used in producing
these products.
Various types of meat products are canned. They range from
essentially all meat, such as canned hams, to comminuted meat
products, such as sandwich spreads, and to mixtures of meat and
other materials, such as stews. The specific processing steps in
canning may vary for different types of meat products. However,
the basic generalized meat canning process in Figure 4 is
representative of a typical practice. This study does not
include pet food production as a canned or a dry product.
Plants in the industry usually produce a mix of products thus
requiring more than one of the generalized processes. There are
a few plants that do specialize in one particular type of product
and process. Meat processors who specialize tend to do so in
meat cuts, canning, or in hams.
The number of processes and the operating procedures vary from
plant to plant. This affects the effluent from a plant and the
waste water treatment requirements. In-plant waste water catch
basins (skimming tanks), screens, etc., are defined as "primary"
waste treatment for purposes of this study. The waste water
after "primary" treatment is defined as the raw waste in this
report.
MANUFACTURING OPERATIONS
Meat processing operations include:
1. Materials and products storage, shipping and receiving
2. Raw material thawing
a. Wet
b. Dry
c. Chipping
3. Carcass/meat handling and preparation
a. Breaking
b. Trimming
c. Cutting
d. Boning
e. Tempering
f. Skinning
4. Seasoning, spicing, and sauce preparation
5. Weighing and batching
6. Grinding, mixing, emulsifying
7. Extruding, stuffing, molding
8. Linking
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CARCASSES
MEAT PARTS
SEASONINGS.
SPICES, ETC.
WATER OR
ICE
SALT
WATER
BRINE
PREPARATION
HOLDING
RECEIVING AND
STORAGE
BREAKING, CUTTING,
TRIMMING
WEIGHING,
BATCHING
GRINDING,
MIXING
EXTRUDING,
STUFFING
COOKING,
SMOKING
PRODUCT
COOLING
PACKAGING
FROZEN MEAT
CHIPPING
WATER OR
ICE
EMULSIFICATION
LINKING
PEELING
FINISHED PRODUCT
STORAGE, SHIPPING
Figure 3. General Process for Comminuted Meat Products
(Sausage, Wieners, Luncheon Meats, etc.)
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MISC. RAW
MAT'LS
MEAT HANDLING
& PREPARATION
MEAT
COOKING
CAN PREPARATION
ft STERILIZATION
RECEIVING,
STORAGE
SAUCE
PREPARATION
BATCHING
CAN FILLING
RETORTING
COOLING
LABELING,
PACKAGING
FINISHED PRODUCT
STORAGE, SHIPPING
1
SPICE a SEASONING
PREPARATION
Figure 4. General Process for Canned Meat Products
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9. Pickle solution application/injection
10. Smoking
11. Cooking
12. Cooling
13. Casing peeling
14. Product holding
15, Bacon pressing and slicing
16. Can preparation
17. Can filling and covering
18. Retorting
19. Packaging
20. Materials recovery (primary treatment)
Some of these operations contribute to the raw waste load of a
meat processing plant. The source and relative quantity of waste
matter are identified in the description of each manufacturing
operation. The materials recovery operation serves as primary
waste treatment and thus removes waste matter and reduces the raw
waste load in the waste water stream. Cleanup of the equipment
and processing areas and the waste generation from cleanup are
described in the following discussion of each manufacturing
operation.
Storage, Shipping and Receiving
The meat-type raw materials and virtually all the finished
products in a meat processing plant require refrigerated storage.
Some of the raw materials and finished products are frozen and
require freezer storage. The meat-type raw materials are brought
into meat processing plants as carcasses, quarters, primal cuts,
and specific cuts or parts that are packaged in boxes. The
seasonings, spices and chemicals are usually purchased in the dry
form and are stored in dry areas convenient to the sauce and
spice formulation area.
The meat processing plants of companies with nationwide sales and
plants located throughout the country also use the storage
facilities of meat processing plants as distribution centers for
products not manufactured at each plant.
The cleaning of freezers is always a dry process and only on rare
occasions would it generate a waste water load. Refrigerated
storage space does require daily wash down, particularly of the
floors, where juices and particles have accumulated from the
materials stored in the refrigerated area. The general policy of
the industry is to encourage dry cleaning of all floors including
storage areas, prior to the final washdown of the floors.
Frequently, actual practices does not include dry cleanup of the
floors before washdown.
Shipping and receiving always involve truck transportation. The
primary source of waste material in this operation occurs in the
transport of carcasses, quarters, and large cuts of meat from the
trucks to the storage area within the meat processing plant.
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Meat and fat particles falling from the raw material are the
primary source of waste material in this operation. The receipt
and transport of other raw materials and finished products
generate essentially now waste load.
Raw Material Thawing
The frozen raw materials received by a meat processing plant are
handled in one of three different ways:
1. Wet thawing
2. Dry thawing
3, Chipping
Materials that are wet thawed are submerged in tanks or vats
containing warm water for the time required to thaw the
particular pieces of meat. The devices used for wet thawing
include simple carts with water covering the meat, vats with
water flowing in and out with the exit temperature of the water
controlled at 10° to 16°C (50° to 60°F) to avoid heating the
outer surfaces of the meat, and equipment where the meat pieces
are suspended in a tank of water and moved by some conveyance
through that tank for a time sufficient to thaw the meat.
Dry thawing involves placing the frozen meat pieces in a
refrigerated room at a temperature above freezing and allowing
sufficient time for the particular pieces of meat to fully thaw.
Chipping involves size-reduction equipment designed to handle
frozen pieces of meat and to produce small particles of meat
which readily thaw and can be used directly in subsequent mixing
or grinding operations. This type of thawing is usually
associated with the production of comminuted meat products.
Both wet and dry thawing generally are used when the entire piece
of meat, or a substantial portion of it, is required for a
finished product, such as hams or bacon.
Wet thawing of raw materials generates the largest quantity of
contaminated waste water. The water used to thaw the materials
is in contact with the meat and thereby extracts water-soluble
salts and accumulates particles of meat and fat. The water used
in thawing is dumped into the sewer after thawing is complete.
The waste load generated in dry thawing is from the thawing
materials dripping on the floor and from the washing of these
drippings into the sewer. The waste from the chipping of frozen
meat materials includes the meat and fat particles remaining on
the chipping equipment and washed into the sewer during cleanup.
Juices extruded from the meat product in the chipping process are
wasted to the sewer, although it is not a large waste load.
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Carcass/Meat Handling and Preparation
This operation includes six different operations that may be
involved in handling and preparing meat materials for subsequent
processing, depending on the processing plant. Each of the six
operations is described separately. All six of the operations
are usually not required to produce a processed meat product.
Breaking
Beef is frequently received by meat processors as halves or
quarters of a carcass. Breaking involves the cutting of these
half and quarter carcasses into more manageable sizes for further
handling and preparation following this operation. The waste
load originates from the cutting and sawing and includes small
meat and fat particles and relatively little liquid, all of which
fall to the floor and are washed into the sewer during cleanup.
Trimming
The removal of excess or unwanted fat and of specific cuts from
larger pieces of meat is done in the trimming operation. The
unwanted fat trimmed from meat products is usually disposed of
through rendering. The materials for disposal are collected and
stored in drums which are picked up by Tenderers and trucked
away. The waste load generated in trimming may be greater than
that generated by the breaking operation. The trimming requires
a greater number of cuts on a specific piece of meat to obtain
the required quality or particular cut desired from the raw
material. The waste water generated by this operation results
from the use of water by the personnel involved in the operation
during the operating day and water required to clean the
equipment and floor of the trimming operation.
Cutting
In the cutting operation the larger pieces of meat are cut or
sawed for the direct marketing of the smaller sections or
individual cuts, or for further processing in the production of
processed meat products. The solid waste materials generated in
cutting are similar to those produced in trimming, plus the bone
dust from sawing the bones. The large pieces are useful in
sausages or canned meats or can be rendered for edible fats and
tallows. The waste materials from the equipment and floor
washdown contribute to the waste load of the meat processing
plant.
Boning
Some raw materials are prepared for the consumer by the removal
of internal bones prior to further processing in manufacturing
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particular products such as hams and Canadian bacon. Boning
might also be performed at the same location as trimming, prior
to the production of various meat cuts. The bones removed in
this operation are disposed of through rendering channels. Meat
and fat particles resulting from this operation are normally
washed into the sewer of a meat processing plant.
Tempering
The processing of some meat products has been found to be
enhanced by adjusting the temperature or moisture content prior
to a specific processing step. This is particularly true in the
production of bacon from pork bellies. If the pork bellies are
to be skinned, tempering in a water-filled vat is frequently used
to improve skin removal. Hams and bacon are frequently tempered
following cooking and smoking by allowing sufficient holding time
in refrigerated storage for the desired temperature to develop
within the particular product. Some meat processors also find it
advantageous to allow the cooked bacon slab to temper in the
refrigerated storage, following pressing and forming of the slab
into the rectangular shape used in the bacon-slicing machines.
The holding , of essentially finished products generates very
little, if any, waste load. However, the water-soaking tempering
technique employed prior to skinning pork bellies does generate a
waste load comparable to that generated by wet thawing of frozen
meat materials by the direct contact of water with the meat
material and subsequent dumping of this water into the sewer.
Skinning
The removal of the pork skin from a piece of meat can be done
either by machine or hand. Skinning is most frequently used in
the preparation of pork bellies for processing into bacon and in
ham production. The common practice in the industry is to use
machines for the skinning process. The skins that are removed
are disposed of through rendering channels. Other products that
require skinning, such as picnic hams, are manually skinned,
frequently at the same time that the raw hams are boned. In
either type of skinning operation, meat and fat particles are
generated and wasted by falling on the floor or by attachment to
the skinning equipment. The subsequent cleanup would wash these
particles into the sewer. In addition, tempering frequently
precedes pork belly skinning which generates the waste water
stream described previously.
Seasonings, Spices and Sauce Preparation
A wide variety of chemicals is used by meat processing to improve
product characteristics including taste, coloring, texture,
appearance, shelflife, and other characteristics important to the
industry. These chemicals include salt, sugar, sodium nitrate,
sodium nitrite, sodium erythrobate, ascorbic acid, and spices
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such as pepper, mustard, and paprika. Other common materials
added in the preparation of processed meat products include dry
milk solids, corn syrup, and water, either as a liquid or as ice.
Other than water, most of these materials are solids, and are
handled in the solid state. The product formulations for the
various finished products produced by a meat processor call for
the specific quantities of chemicals and seasonings. These are
preweighed and prepared for use in a specific batch in a dry
spice preparation area. These spices and chemicals are weighed
into containers and added to batches in the grinding or mixing
operation. Very little waste of either a dry or wet nature is
generated by the specific operation of seasoning and spice
formulation. Sauces are prepared for use in canned meat products
particularly. Sauces are wet mixtures of seasonings, spices, and
other additives described above, as well as meat extracts and
juices, and are used to prepare a gravy type of product.
Typically, the meat materials are mixed into the sauce in
preparing a finished product mixture; thus, large kettles or vats
are involved in preparing the sauce and mixing the meat and sauce
to prepare the final product. Significant quantities of waste
are generated in the preparation and handling of sauces and in
cleaning of kettles. The residual materials are washed out of
the kettles directly into the sewer and contribute significantly
to the raw waste load of a meat processor that prepares a canned
meat product.
Weighing and Batching
The meat processing industry uses batch-type manufacturing
operations in all but a few instances. The formulation or
specification of type and quantity of materials that go into each
unit of production, or batch, are controlled according to
specifications established by the individual meat processing
companies in accordance with government standards for the
finished product. The quantity of lean and fat raw materials that
go into each batch are weighed and placed in portable tubs. The
portable tubs of weighed raw material are identified for a
specific product and moved to the next manufacturing operation.
The weighing and batching area is frequently located in one of
the refrigerated raw material storage areas. The operation
involves a considerable amount of manual handling of meat
products and pieces of trim fat. Liquids, including meat juices
and water, frequently drip from the raw materials onto the floor
of the batching area. Particles also drop off in the handling
process. The tubs that are used to hold the raw materials and
the batches of raw material contain liquids and solids that are
wasted to the sewer after batches have been dumped into
subsequent processing equipment.
Cleanup of the tubs and handling equipment is carried out as
needed during the production period, and at least once a day.
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Grinding, Mixing and Emulsifying
All processed meat products that are not marketed as cuts or as
specific items such as bacon or ham, or used in large pieces, are
processed at least through a grinding step in manufacturing a
finished product. Grinding is the first step in reducing the
size of meat pieces for use as a processed meat product such as
hamburger, or in preparation for further mixing, blending, or
additional size reduction. Grinders are frequently equipped with
plates through which meat is forced or extruded. Grinder plates
with holes measuring 1/8 to 3/8 are in most common use. In
addition to size reduction, grinding equipment may be used to
prepare a mixture of various ingredients such as meat products
from different types of animals or lean and fatty meat products.
The particle size of the meat ingredients in a product is
critical. Larger particle size is required in hamburger or fresh
pork sausage products. A slightly smaller particle size is
required in manufacturing dry or semi-dry sausages. Various
sausages, including wieners and some luncheon meats, are prepared
by a substantial size reduction or comminution of the meaty raw
materials. These products involve a stable sausage emulsion—a
suspension and uniform dispersion of fat droplets or globules
throughout a mixture so that the mixture takes on a homogeneous
appearance.
Equipment is available to the meat processor that blends or mixes
the various ingredients, including the meat materials, to produce
stable emulsions. One type of equipment—the "silent cutter"—
involves the use of numerous knife blades spinning at a high
velocity to reduce the particle size and to produce a stable
emulsion. The other type of equipment used to produce an
emulsion has the appearance of a common type of dry blender
comparable to the ribbon blender.
Control of the type of raw materials used, the sequence of
addition, the time and intensity of grinding, blending, or
emulsifying are all critical to the quality of the finished
product. Some movement of materials is usually involved in these
operations because the stepwise processing is required for each
batch. This movement is accomplished by pumping or manually
using portable containers.
Solid waste materials are generated from these operations by
spillage in handling and movement of materials and in cleanup and
preparation of equipment for different types of products.
These manufacturing operations are among the major contributors
to the waste load in a meat processing plant as a result of
equipment cleanup. Since the processing step involves size
reduction of lean and fatty materials and the preparation of
stable mixtures of meat and other ingredients, these materials
tend to coat equipment surfaces and collect in crevices,
recesses, and dead spaces in equipment. All of these materials
are removed in cleanup and washed into the sewer. This is in
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contrast to larger size particles that can be readily dry-cleaned
off a floor prior to washdown and thereby reduce the raw waste
load in the waste water stream. Any piece of equipment that is
used in any of these operations is cleaned at least once per
processing day and may be rinsed off periodically throughout the
day, thereby generating a fairly substantial quantity of waste
water and contributing to the raw waste load.
Extrusion, Stuffing and Molding
Following the preparation of a stable emulsion or mixture of
ingredients for a processed meat product such as wieners or
sausage, the mixture is again transported either by pump or in a
container to a manufacturing operation where the mixtures are
formed or molded into the finished product. Sausage casings and
stainless steel molds are commonly used as containers in this
operation. Either natural casings, which are the intestines from
some types of animals, or synthetic casings, which are only used
in the formation of the products and then are peeled and disposed
of before the product goes to the consumer, may be used in
producing sausages and wieners and in some kinds of luncheon
meats. The stainless steel molds are most commonly used to
prepare the square shape characteristic of some of the luncheon
meats.
In the casing, stuffing, or mold filling operation a product
mixture is placed in a piece of equipment from which the product
mixture is either forced by air pressure or is pumped into the
container to form a uniform and completely filled container
resembling the shape of the finished product.
Water is used to prepare the natural casings for use in the
stuffing operation and the stainless steel molds are cleaned and
sterilized after every use. The primary source of waste load and
waste water occurs in the cleanup of the equipment used in this
operation. As in the previous operation, the residual emulsions
and mixtures contribute significantly to the waste load because
of their propensity to stick to most surfaces that they come in
contact with and to fill crevices and voids. All equipment used
in this operation is broken down at least once a day for a
thorough cleaning. This cleanup is designed to remove all
remnants of the mixtures handled by the equipment and this
material is washed with the waste water into the sewer, thereby
contributing to the waste load.
Some spillage of material occurs in this operation. Spillage
occurs during the transport of the material from grinding and
emulsifying to the extrusion operation, and particularly in the
extrusion or stuffing operation when the material being extruded
exceeds the capacity of the container and overflows.
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Linking
This manufacturing operation is simply the formation of links or
specific sized lengths of product in a casing. This is done by
twisting or pinching the casing at the desired length for the
specific finished product, either mechanically or manually. A
small stream of water is used to lubricate the casing to avoid
breakage or splitting. When the full length of each casing has
been linked, the product is hung on a rail hanger, called a
"tree," in preparation for the next manufacturing operation
(usually cooking and smoking).
Unless a casing splits or breaks, there should be no significant
amount of raw waste load contributed by this operation. The
equipment that is used is thoroughly washed after use. The
hangers which hold the products through the cooking and smoking
step become coated with greasy substances, which are washed off
and into the sewer after each use. In addition, a standard
maintenance practice is to coat the hangers with a thin film of
edible oil to protect them from rusting. This oil is ultimately
washed off either in the over showering or in the washing of the
hangers following each use. Some of the larger operations use
automated spray cabinets for "tree" washing.
Pickle Application/Injection
A pickle or caring solution is prepared with sugar, sodium
nitrite, sodium nitrate, and salt as the main ingredients in
water. The pickle solution preparation area frequently is
separated physically within the plant from the actual point of
use. There are various types of injection used to introduce the
pickle solution into the interior of a meat product. Pickle
solution may also be applied by holding the meat product in a
curing brine for an adequate length of time for the pickle to be
absorbed. Or the pickle may be injected or pumped into hams or
similar products by introduction of the brine through an artery
or the vascular system if it is relatively intact. The product
may be injected through numerous needles which penetrate the ham
over a large area. Hams, for example, are usually pumped to 110
or 120 percent of their green weight or starting weight. The
injection may also be done on both sides to assure thorough and
uniform pickling. Following the pickle injection or application,
it is common practice to store the product in tubs with a
covering of pickle solution for some time.
Pickling solutions are high in sugar and salt content,
particularly the latter. The large amount of spillage in this
operation comes from runoff from the pickle injection, from
pickle oozing out of the meat after injection, from dumping of
cover pickle, and from dumping of residual pickle from the
injection machine at the end of each operating day. These
practices contribute substantially to the waste water and waste
load from a meat processing plant. Many of the ingredients of
pickle solutions represent pollutional material in high
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concentrations and add significantly to the raw waste load from
the pickle operation. Cleanup of the tubs or vats holding the
product in brine solutions and cleanup of the pickle injection
machines is required at least once per day, or after each use in
the case of the vats. This generates additional waste load and
waste water from a meat processing plant.
Cooking, Smoking, and Cooling
Most of the meat products are cooked as part of the standard
manufacturing procedure. Notable exceptions are fresh pork
sausage, bratwurst, and bockwurst. The processed meat products
may be cooked with moist or dry heat. Cooking sausages
coagulates the protein and reduces the moisture content, thereby
firming up the product and fixing the desired color of the
finished product. Large walk-in ovens or smokehouses are in
general use throughout the industry. These smokehouses are
equipped with temperature controls, humidity controls, water
showers, and with the facility to provide smoke for smoking
products.
The smoking of meat products gives the finished meat product a
characteristic and desirable flavor and also some protection
against oxidation and an inhibiting effect on bacterial growth in
the finished product. Smoke is most commonly generated from a
hardwood sawdust or small-size wood chip. Smoke is generated
outside the oven and is carried to the oven and introduced
through duct work. A small stream of water is used to quench the
burned hardwood sawdust before dumping the sawdust to waste. The
most common operation is to overflow the water from this
quenching section and to waste the water into the sewer. One
plant slurried the char from the smoke generator, piped it to a
static screen for separation of the char from the water, and then
wasted the water.
The actual cooking operation generates waste water when steam or
hot water is used as the cooking medium, such as in cooking
luncheon meats in stainless steel molds.
The steam condensate and hot water are wasted to the sewer from
the cooking equipment. It is standard practice to shower the
finished product immediately after cooking to cool the product.
This also generates a waste water stream containing a waste load
primarily of grease.
Cleanup of the cooking ovens is not done every day, but at the
discretion of the plant management. The typical practice is to
clean each oven and the ductwork for the heated air and smoke
circulation at least once a week. This cleaning includes the use
of highly caustic cleaning solutions to cut grease and deposits
from the smoking operation that are deposited on the walls,
ceiling, and ductwork in the ovens. The effluent from such a
cleaning operation is noticeably dark colored. This color is
thought to be the result of creosote-type deposits and fatty
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acids from the smoke. The other waste load generated in oven
cleanup is the grease from the walls and floors resulting from
cooking the various products.
In total quantity, the waste load and waste water generated in
this cleanup is not particularly significant. However, there is
the noticeable coloration of the waste water during cleanup and,
depending on the extent of the use of caustic, an increase in the
pH of the waste water.
Processed meat products are cooled in different ways, depending
on the type of product. Sausage products may be cooled while
still in the oven or smokehouse with a spray of cold water or
brine solution. Or they may be cooled in the aisle immediately
outside the smokehouse, to save heat and increase productivity.
The brine solution is used to achieve a lower spray temperature
and thereby a more rapid cooling of the product. The brine is
recirculated until it is judged to be excessively contaminated to
permit efficient use, at which point it is usually discharged
into the sewer.
Hams and bacon products are not exposed to water, but instead are
moved quickly from the smokehouse to a refrigerated room with a
very low temperature (-35°C) and higher than normal air
circulation to achieve rapid cool-down. The hams and bacon may
drip a small quantity of juice or grease onto the floor of the
cold room before the surface temperature of the product reaches a
point which precludes any further dripping. Cleanup of the floor
results in wasting of these drippings into the sewer.
Canned meat products and products prepared in stainless steel
molds are usually cooled by submersion in cold water. The water
is usually contained in a tank or raceway where it may be flowing
at a very low speed in a direction countercurrent to the movement
of the cans or molds. Depending on the type of installation and
product, it was found that the water used in cooling need not be
dumped, and in fact can be continually recirculated with only a
nominal amount of blow-down to remove accumulated solids, just as
would be done in operating a boiler. In other situations,
usually where smaller quantities of water are involved and
luncheon meat molds are being cooled, the water is dumped more
frequently: up to once a day. This dumping is necessary because
the seal on the molds is not tight enough to prevent leakage of
juices and grease to the exterior of the molds.
The only cleanup of cooling equipment which would generate a
waste load is that from cleanup of the floors in the cold rooms
where hams and bacon are cooled. This load would be small in
comparison to others from the plants.
Casing Peeling
Synthetic casings made from a plastic material are used in the
production of a large number of wieners in the meat processing
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industry. These casings are not edible and therefore must be
removed from the wieners after cooking and cooling, but prior to
packaging for sale to the consumer. The peeling equipment
includes a sharp knife which slits the casing material, a small
spray of steam to part the casing from the finished wiener, and a
mechanism to peel the casing away from the wiener. Casing
material is solid waste that results from this operation; it is
collected and disposed of as part of the plant refuse. The
slitting mechanism will occasionally penetrate the wiener in
addition to the casing and cut the wiener, rendering it useless
as a finished product. However, these pieces of wiener are not
wasted but are used in other products prepared in the plant. The
steam used in the casing peeling results in a small water stream
from this operation, but it is so small it is of no real
consequence.
The equipment is cleaned at the end of every processing day and
may contribute a small quantity of waste load as a result of
wiener particles that may be attached to various parts of the
mechanism and are subsequently washed into the sewer during
cleanup. The volume of waste water and the waste load is
relatively insignificant in comparison with other waste sources.
Product Holding/Aging
Some processed meat products require holding or aging as part of
their production process. Hams, dry sausage and some bacon are
examples of products that require intermediate or finished
holding periods before the product is shipped out of the meat
processing plant. The holding operation requires space and some
means of storing the particular meat product in the holding area.
These holding areas are refrigerated and some drippings
accumulate on the floor. This floor area, as with the other
processing floors, is cleaned once every processing day. The
quantity of waste water and the waste load from the cleanup of
these holding areas is minimal in comparison with many other
sources within the meat processing plants.
Bacon Pressing and Slicing
After the bacon has been cooked, smoked, cooled, and held for the
required time, two processing steps are required before the
product is ready for packaging. Bacon slabs are irregular in
shape after cooking, smoking and cooling, and bacon slicing
equipment is designed to handle a slab with a fairly rectangular
shape. This facilitates the production of the typical uniform
bacon slice expected by the consumer. The bacon slabs are placed
in a molding press which forms the slabs into the desired
rectangular shape.
Two different slicing procedures are used within the processing
industry after the slabs have been pressed into rectangular
shapes. some plants slice the bacon slabs immediately after
pressing. Others prefer to return the molded bacon slabs to a
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refrigerated holding area to allow the temperature within the
slab to cool down. Each approach is successful and the method
actually used appears to depend only on individual preference for
a given operation.
Bacon slicing is usually a high-speed operation in which slabs
are rapidly cut, the strips of bacon placed on a cardboard or
similar receptacle to a specified weight, and then fed onto a
conveying system which delivers the bacon to packaging.
There is little waste generated in bacon pressing and slicing
except for random pieces of bacon which may fall on the floor.
These pieces are of sufficient size to be readily picked up in
dry cleaning the floors before washdown. The equipment is
cleaned at the end of every processing day. There are some
particles as well as a fairly complete covering of grease on all
parts of the equipment that come in contact with the bacon slabs.
All of this is washed off in the cleanup operation. The quantity
of waste water generated in cleaaup and the waste load from this
cleanup is again relatively small in comparison to other sources.
Can Preparation, Filling, and Covering
The containers used to hold the canned meat products must be
prepared before filling and covering. The cans are thoroughly
cleaned and sterilized. The wet cans are transported from the
preparation area to the processing area for filling and covering.
Water is present "all along the can lines from preparation to
filling and covering. The cans go through one last steaming just
before entering the can filling machine.
Can filling is a highly mechanized high-speed operation. It
requires the moving of the meat product to the canning equipment
and the delivery of that product into a container. The high
speed and the design of the equipment results in an appreciable
amount of spillage of the meat product as the cans are filled and
conveyed to the covering equipment. At the can covering station,
a small amount of steam is introduced under the cover just before
the cover is sealed to create a vacuum within the can when it
cools. This steam use also generates a quantity of condensate
which drains off the cans and equipment onto the floor. The
operation of the filling and covering equipment results in a
substantial quantity of waste water containing product spills
that is wasted to the sewer. Canning plants that have more than
one filling and covering line will have a waste load that is
roughly proportional to the number of such lines in use.
All of the equipment is washed at least once per day at the end
of the processing period. If a can filling machine is to be used
for different products during the day, it will usually be cleaned
between product runs. Meat products are frequently canned with
gravy-type sauces, or the meat product itself has been comminuted
to a small particle size and mixed to produce a flowable mixture.
This type of canned product results in greater contamination of
equipment wash water because of the tendency of the product
27
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mixture to coat surfaces it comes in contact with and to fill all
dead spaces and crevices in the equipment. The equipment is
highly mechanized with many moving parts and is designed to be
cleaned intact rather than being dismantled first, as is grinding
and mixing equipment. Cleaning the equipment while it is intact
requires a high velocity water stream or steam to remove all food
particles from the equipment. The tendency of operating
personnel is to use greater quantities of water than necessary to
clean the equipment. This results in large quantities of waste
water with substantial waste loads from canning operations.
The equipment used in transporting the meat product to the can
filling equipment also must be cleaned after it has been used on
a specific product, and it is always cleaned at the end of the
processing day. This equipment is usually broken down, and the
product characteristics that contribute to large waste loads, as
described above, also generate large waste loads in cleanup of
the transport equipment as well.
Some ham products are canned by manually placing ham pieces in
cans. Manpower is used in place of mechanical equipment because
the pieces are random sized and the packer desires to have a
full, uniform appearance for the canned product. A small amount
of gelatin is added to the canned product to fill out the dead
space and to provide moisture to the product. Waste generated
from this type of operation probably is somewhat less than from
high-speed canning equipment.
Retorting
The pressurized cooking of canned meat products is called
retorting. The purpose of this operation is to destroy bacteria
in the canned product inside the can and thus to extend the
shelf-life of the product. Live steam is used as the heating
medium in retorting, and it is common practice to bleed or vent
steam from the retort vessels. Virtually no waste water or waste
load is generated by the retorting operation unless a can in a
particular batch should accidentally open and spill the contents
of that can into the retort; this requires the wasting of the
contents of that can and the cleanup of the retort vessel. This
rarely happens, and the retort vessels, as a matter of normal
practice, are not cleaned. The cans that are placed in the
retort vessels are normally free of any potential source of waste
load.
Packaging
A variety of packaging techniques is used in the meat processing
industry. These techniques include the standard treated
cardboard package, the Cry-O-Vac type of package, the bubble
enclosure type packages used for sliced luncheon meats and
wieners, and the boxing of smaller containers or pieces of
finished product for shipment. In some techniques of packaging a
28
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substantial amount of product handling is involved. This may
result in some wasted finished product. However the size of the
pieces of wasted finished product are such that there is little
reason for it to be wasted to the sewer. Instead, it should be
returned for subsequent use in another processed product or
directed to a rendering channel.
Cleanup of the equipment would be the only time when water would
be generated by the packaging operation. Small quantities of
water are adequate for cleanup of this equipment, and only small
quantities of waste would be generated in cleanup of the
packaging equipment.
Materials Recovery
The waste water from a plant usually runs first through catch
basins or grease traps, or occasionally, flotation units. The
primary purpose of these systems is usually the recovery of
grease, which goes into inedible rendering. The very important
function of removal of pollutants is also served. Grease
recovery most often has been the controlling factor, so the
systems may be considered part of the manufacturing operation
rather than a stage in pollution abatement. The most widely used
method of solids recovery uses a catch basin. Solids settle to
the bottom and are removed continuously or periodically; grease
floats to the top and is scraped off, continuously in some
plants. For effective recovery, these units usually have greater
than a 30-minute detention time and are designed to minimize
turbulence.
The best grease recovery is accomplished by using dissolved air
flotation in a tank. The tanks are usually large enough to
retain the liquid between twenty minutes and an hour. Air is
injected into a portion of recycled effluent or it is injected
into the total waste water stream before it enters the tank. The
liquid is pressurized to "supersaturate" it with air. The liquid
then enters the tank where air bubbles coming out of solution
rise to the surface, carrying grease particles with them. The
grease is removed by skimmers. While the tanks are not designed
for the most effective removal of settleable solids, some solids
settle to the bottom and are scraped into a pit and pumped out.
In some cases, flotation is added to other recovery systems for
the primary purpose of pollution abatement.
In addition to these recovery systems, some plants also recover
solids from the waste water, before entering the grease removal
system, by using self-cleaning screens, either static, vibrating,
or rotating. The solids that are recovered, as well as the
solids from the catch basin, are directed to rendering channels.
29
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PRODUCTION CLASSIFICATION
The U.S. Office of Management and the Budget in Standard
Industrial Classification Manual classifies the meat products
industry under Standard Industrial Classification (SIC) group
code number 201 (Major Group 20) . The meat processing plants are
classified as Industry No. 2013, which is defined as:
"Establishments primarily engaged in manufacturing
sausages, cured meats, smoked meats, canned meats,
frozen meats, natural sausage casings, and other
prepared meats and meat specialties, from purchased
carcasses and other materials. Sausage kitchens and
other prepared meat plants operated by packing houses
as separate establishments also are included in this
category."
Bacon, side and sliced: mfpm*
Beef, dried: mfpm
Bologna: mfpm
Boneless meat: mfpm
Calf's foot jelly
Canned meats, except baby foods: mfpm
Casings, sausage: natural
Corned beef
Corned meats: mfpm
Cured meats: brined, dried, and salted: mfpm
Dried meats: mfpm
Frankfurters, canned or not canned: mfpm
Hams: boiled, boneless, roasted, and smoked: mfpm
Hams, canned: mfpm
Head cheese: mfpm
Lard: mfpm
Luncheon meats, canned
Meat extracts: mfpm
Meat products: cooked, cured, frozen, smoked, spiced and
boneless: mfpm
Pastrami: mfpm
Pigs' feet, cooked and pickled: mfpm
Pork: pickled, cured, salted, or smoked: mfpm
Potted meats
Puddings, meat: mfpm
Roast beef
Sandwich spreads, meat: mfpm
Sausage casings, natural
Sausages: mfpm
S cr appl e: m fpm
Smoked meats: mfpm
Spreads, sandwich: meat: mfpm
Tripe: mfpm
Vienna sausage, canned or not canned
*mfpm: Made from purchased materials or materials transferred from
another establishment.
30
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ANTICIPATED INDUSTRY GROWTH
Shipments of meat processing products in 1972 were $4 billion and
are expected to rise by about twenty percent to $U.8 billion in
1973. The U.S. Industrial Outlook: 1974 estimates that the
typical growth rate of 6 to 8 percent per year will be sustained
through 1980 for American producers.
Factors that should contribute to growth can be distinguished
from those that act to restrain this growth. A growing
population and rising family incomes will continue to maintain
consumer demand for meat products. Historically, as incomes of
American families have grown, they have substituted higher priced
food products such as meats and convenience foods for the bread
and potatoes in their diets. Demand for beef, for example, has
continued to grow on a per capita basis as well as in total. In
1972 the average American consumed 115 pounds of beef, which was
two pounds more than in 1971. And, of importance to the meat
processing industry, are the larger quantities of portion-
controlled meats being processed in response to demands by fast-
food outlets, hotels, restaurants, and other institutions.
The primary restraint to continuing growth of the processed meat
industry is high prices. The availability of meat substitutes
and their use in meat products may have some effect on the
industry. However, the direction and degree of that effect is
largely indeterminant at this time and no projections have been
made to predict.this impact.
31
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-------
SECTION IV
INDUSTRY CATEGORIZATION
CATEGORIZATION
In developing effluent limitations guidelines and standards of
performance for the meat processing industry, a judgment was made
as to whether limitations and standards are appropriate for
different segments (subcategories) within the industry. To
identify any such subcategories, the following factors were
considered:
o Waste water characteristics and treatability
o Finished product mix
o Manufacturing operations
o Raw materials
o Age and location of production facilities
o Plant size.
After considering all of these factors, it was concluded that the
meat processing industry consists of two major groups: Small
Processors and Large Processors.
A small processor is a meat processing plant that produces up to
2730 kg (6000 Ib) per day of any type or combination of finished
processed meat products (finished products as defined in the
listing in the previous Section.
A large processor is a meat processing plant that produces more
than 2730 kg (6000 Ib) per day of processed meat products. The
large processors group is further subdivided into the following
four subcategories:
1. Meat cutter—a large processor that produces only fresh
meat cuts as its finished product;
2- Sausage and luncheon meat processor—a large processor
that produces any mix of finished products except hams
and canned meat products;
3. Ham processor—-a large processor that produces any mix
of finished products, including hams, but no canned
meat products; this subcategory also includes those
plants that produce only hams;
33
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4. Canned meats—a large processor that produces any mix
of finished products that includes canned meat products;
this subcategory also includes those plants that produce
only canned meat products.
Canned pet foods are not included in the meat processing
industry. Also, it should be noted that the term "finished
products" refers to the listing of such products provided in
Section III under the heading. Production Classification.
Relevant exclusions from this list for any given subcategory are
provided in the definitions above. Thus, for example, a ham
processor must accomplish some degree of cured/smoked ham
production, perhaps entirely producing hams, but may also
accomplish some meat cutting, sausage or luncheon meat
processing, smoked meat processing, etc., but will carry out no
canning of meats. On the other hand, small processors may
produce any one, or combination of products listed, but are
separated on the basis of daily production level. With respect
to the meat cutter subcategory it should be explained that thrust
of the designation is to isolate those operations which perform
the function of cutting whole or partial beef, sheep, or swine
carcasses into steaks, roasts, boned meats, portion cuts, etc.
All plants in this subcategory surveyed in this study consider
themselves "meat cutters" as opposed to retail/wholesale
distributors (urban meat distributors, grocery warehouses, etc.)
which carry out the same functions. Nevertheless, as an
industrial "point source" some overlap between cutters and
distributors may occur (particularly in ultimate disposition of
products to institutional restaurant or hotel volume buyers) in
which case specific functions must be evaluated. Grocery stores,
for example are not affected.
The differences between the five subcategories and the
relationships between them are shown schematically in Figure 5.
The initial division of the industry is based on size, with the
dividing point set at a production rate of 2730 kg (6000 Ib) per
day of finished products. Product mix varies within both the
small and the large processing groups. However, the differences
in product mix coupled with differences in waste water
characteristics take on significance in relation to raw waste
loads only in the large processing plants. Therefore, the four
subcategories based on product mix are established only in the
large processor group. The critical finished product
distinctions are as indicated.
In summary, the designated subcategories have been given a
nomenclature and definition to convey a "primary characteristic"
of plants in any given group. There is flexibility in the
definitions to account for intra-subcategory differences
associated with the variety of possible
Notwithstanding this flexibility, there is no
products.
information
available to indicate any significant excursion by a given
beyond the bounds of the chosen subcategorization.
plant
34
-------
GO
tri
SUBCATEGORY I
SMALL PROCESSOR
< 2730 Kg/day
ANY MIX OF
PRODUCTS
SUBCATEGORY 2
MEAT CUTS, ONLY
NO OTHER
PRODUCTS
MEAT PROCESSING
INDUSTRY
LARGE PROCESSOR
> 2730 Kg/day
SUBCATEGORY 3
SAUSAGE AND
LUNCHEON MEATS
SUBCATEGORY 4
HAM PROCESSING
SUBCATEGORY 5
CANNED MEATS
NO HAMS OR
CANNED MEATS
NO CANNED
MEATS
ANY OTHER
PRODUCTS
Figure 5. Subcategories in the Meat Processing Industry
-------
RATIONALE FOR CATEGORIZATION
Waste Water Characteristics and Treatability
Industrial practices within the meat processing industry are
diverse and produce variable waste loads. It is possible to
develop a rational division of the industry, however, on the
basis of factors which group plants with similar raw waste
characteristics. The waste water characteristic used in
characterizing the categories of this industry segment is five-
day biochemical oxygen demand (BOD5) in units per 1000 units of
finished product: kg BOD^/kkg finished product (FP) (Ib
BOD5/1000 Ib FP). BOD5 provides the best measure of waste load
pollution parameters measured, and more data are available on
BODS than for all other parameters except suspended solids.
Suspended solids data serve to substantiate the conclusions
developed from BOD5, in characterizing the industry subcategories.
As explained below, the derivation of the subcategories, using
BOD5 as the common measure, evolved on the basis of readily
discernible groupings by plant size, finished product, and
manufacturing process. The factors of age of plant, raw
materials, and plant location seemed to verify the selected
subcategories. The major plant waste load is organic and
biodegradable: BOD5, which is a measure of biodegradability, is
the best measure of the load entering the waste stream from the
plant. Furthermore, because biological waste treatment processes
are used, BOD5 also provides a useful measure of the treatability
of the waste and the effectiveness of the treatment process.
Chemical oxygen demand (COD) measures total organic content and
part of the inorganic content of the waste stream. COD is a good
indicator of change in oxygen demand in treatment, but does not
relate directly to biodegradation, and thus does not indicate the
oxygen demand on a biological treatment process or on a stream.
As developed in more detail in Section V, specific differences
exist in the BOD5> load of the raw wastes for five distinct groups
of meat processing operations. As defined above, these groups
are substantiated as subcategories on the basis of waste load.
Table 1 presents a summary of average production, waste water
volume, and BOD5 load for each subcategory.
A number of additional parameters were also considered. Among
these were nitrites and nitrates, Kjeldahl nitrogen, ammonia,
total dissolved solids, chlorides, and phosphorus. In each case,
data were insufficient to justify categorization on the basis of
these specified parameters; on the other hand, the data on these
parameters helped to verify judgments based upon BOD5.
Judging from secondary waste treatment effectiveness and final
effluent loading data for this industry and the similar but more
extensive data on the meat packing industry, waste water from
plants throughout the industry contain the same constituents and
are amenable to the same kinds of biological treatment
36
-------
technologies. It was anticipated that geographical location, and
hence climate, might affect the treatability of the waste to some
degree. Climate will occasionally influence the kind of
biological waste treatment used, but has not influenced the
ultimate treatability of the waste or potential treatment
effectiveness, with the appropriate operation and maintenance.
The small processor generates, on the average, a significantly
smaller quantity of waste water, both in absolute terms and
normalized on the basis of volume of waste water per 1000 units
of finished product, in comparison with most of the industry.
The average waste water from 40 plants in the small processor
subcategory is 3335 liters per kkg (400 gal. per 1000 Ib) of
finished product. The total waste water quantity represents
about 8.0 percent of the cut meats category average and about 0.7
percent of the next lowest subcategory, ham processors. This
results in a unique capability to treat waste water for the small
processor, which is confirmed in actual practice by plants in
that subcategory. Among the 85 small processing plants in the
North Star survey, all ten that treat their own waste water have
achieved no discharge of waste water through the use of septic
tanks and subsoil seepage systems. The other 75 plants discharge
their waste water to municipal sewer systems.
Finished Product Mix
The finished product mix of large meat processing plants provides
an important basis for subcategorization and fully substantiates
the BOD characteristic of the waste water discussed above.
Analysis of product mix variation and its effect on the waste
load of small processors confirms the decision to have a single
subcategory for small processors.
The cause and effect relationship between raw waste load, as
measured primarily by BOD£, and product mix is more apparent than
that between raw waste load and manufacturing operations.
However, the rationalization of product mix as a factor in
subcategorization rests on the differences in manufacturing
operations used to produce a given product mix. It is the
manufacturing process or discrete grouping of processes required
to produce a specific product(s) that generates a typical raw
waste load for a specific subcategory that differs significantly
from that for another subcategory. But the distinction and
definition of the subcategories is valid and more clearly
understood when expressed on the basis of product mix. Table 2
presents data on the distribution of the raw waste load
frequencies for each subcategory. Statistical tests of these
distributions further validate the proposed categorization.
Tests of statistical significance, including the "t" test on the
difference of the means of the raw waste load of the sausage and
luncheon meat processors and of ham processors, and a chi square
computation on the raw waste load distributions yields confidence
levels greater than 95 percent that the subject subcategories are
indeed different and distinct. In addition, one of the two ham
37
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processing plants at the unusually low BOD^ loading for that
subcategory can be explained by the meticulous operating
practices used in that plant.
There are few large processors that produce only meat cuts. In
our sample of six plants, three plants average 116,000 kg
(225,000 Ib) of production per day and the other three average
8200 kg (18,000 Ib) per day. Thus, if this sample is
representative, plants in this subcategory tend to be very large
or very small. However, the waste water flow from these plants
is uniformly low, averaging about 37,850 liters (10,000 gallons)
per day; and the raw waste load, reported by two of the plants,
averages 0.52 kg BOD5/kkg (0.52 lb/1000 Ib) FP. This low waste
load is only 20.0 percent of the next lowest average for any
other large processor subcategory.
At the other end of the waste load spectrum for this industry is
the large processor who has canned meat products in his line.
Such plants are closely grouped in terms of high production
volume, with an average of 81,000 kg (178,000 Ib) per day, and a
high raw waste load average of 11.5 kg/kkg (11.5 lb/1000 Ib) FP
as indicated in Table 1. The manufacturing equipment and
operating procedures used in canning result in large quantities
of water. All of these factors substantiate the selection of
this separate subcategory.
The remaining plants in the industry had widely variable product
mixes and raw waste loads. The one factor that separated them
into fairly distinctive groups, based on raw waste load, was
whether or not the plant produced hams. The average production
quantity and waste water flow of these two subcategories are not
significantly different. However, as indicated in Tables 1 and 2
and in Figure 6, there is a substantial difference in raw waste
load between plants that process hams and those that do not.
This distinction does not include meat product canners, which are
in a separate subcategory. The reason for the difference in raw
waste load is reasonably attributable to the manufacturing
operations, which will be discussed below. However, as discussed
previously, the rationalization and description of the
subcategories is best related to differentiation in product mix.
Manufacturing Operations
Manufacturing operations as they were reflected in the finished
product mix, also indicated a requirement for subcategorization
of the meat processing industry. The use of specific operations
in the production of each product group, and the raw waste load
and waste water generated by those operations, as described in
Section V, support the categorization as stated. Even though the
industry operating practices and the level of technology used in
the manufacturing operations are substantially uniform throughout
the industry in both large and small processors for any given
product or group of products, a change in products clearly
indicates differences in manufacturing procedures. However, the
38
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Table 1. Meat Processor Industry Profile by Subcategory
Average Production, kkg/day
(lOOO Ib/day)
Range, kkg/day
Standard dev, , kkg/day
No. observations
Average total waste water, I/day
(gal.i/day)
Range, liters/day
Standard dev. , liters/day
No. observations
Average normalized waste water,
liters/kkg FP
(gal./lOOO Ib FP)
Range, liters/kkg FP
Standard dev. , liter/kkg •
No . observations
Average raw waste BODs load
kg/kkg FP
(lb/1000 Ib FP)
Range, kg/kkg FP
Standard dev. , kg/kkg FP
No . observations
Small
Processor
0.95
(2.1)
0.14-2.3
0.59
85
3200
(840)
40-34000
2800
40
3335
(400)
83-25,000
7200
40
1.06
(1.06)
0.99-1.1
0.1
2
Meat Cutter
63
(138)
6.4-158
64
6
38,000
(10,000)
1100-38,000
16 , 800
4
600
(72)
175-3635
1690
4
0.52
(0.52)
0.23-1.09
0.5
2
Sausage & Luncheon
Meats Processor
48
(105)
3.5-227
62
22
454,000
(120,000)
4900-1,332,000
416,000
19
9600
(1150)
1084-26,100
7500
19
2.65
(2.65)
0.5-5.4
1.9
12
Ham Processor
33
(73)
3.6-227
44
21
353,000
(93,000)
11,000-1,510,000
500,000
20
10,600
(1270)
288-29,200
7425
20
5.5
(5.5)
0.24-16.2
4.1
14
Meat Canner
81
(178)
33-204
57
9
908,000
(240,000)
151,000-4,200,000
1,300,000
8
11,250
(1350)
3170-20,375
6050
8
11.5
(11.5)
0.8-24
7.4
8
-------
Table 2, Number of Plants in Each Subcategory with Indicated Raw Waste Load
Number of Plants in Each Subcategory with Indicated Raw Waste Load
Subcategory
Small Processor
Meat Gutter
Sausage and
Luncheon Meat
Processor
Ham Processor
Meat Canner
Raw Waste Load (kg BOD^/kkg FP)
<1
1
1
3
2
1
1.0-
1.9
1
1
3
2.0-
2.9
1
1
3.0-
3.9
1
1
4.0-
4.9
2
5
5.0-
5.9
2
1
6.0-
6.9
3
7.0-
7.9
8.0-
8.9
1
9.0-
9.9
1
10.0-
10.9
1
11.0-
11.9
12.0-
12.9
1
13.0-
15.9
16.0-
18.9
1
2
19.0
21.9
^22
1
1
-------
production volume and associated waste load do not justify
product distinction in the small processor subcategory.
Such generalized manufacturing operations as cooking, smoking,
curing, and cooling overlap various products and do not lend
themselves to a distinctive grouping of plants strictly on the
basis of these types of production operations.
Raw Materials
The characteristics of raw materials help to substantiate the
above categorization and are generally consistent for each
subcategory. The raw materials include animal carcasses and meat
parts, both frozen and unfrozen, water, seasonings and spices,
chemicals, and fuel. Although different forms of raw material
require some different processing techniques, these effects are
best handled by incorporation into other factors. For example,
production variations are accounted for by normalizing; i.e., by
dividing waste parameter values by the daily finished product
quantity, to facilitate comparisons and analysis of individual
plant practices; this gives a waste load per unit of production
quantity. The effects on waste load of differences in the plant
processes that are dependent on raw materials, per se, are not
significant.
A relationship .was found between raw waste load and water use
within a given subcategory, as described in Section V.
Generally, the BOD5 raw waste load will increase as the
normalized waste water volume increases. Variations in water
flow between subcategories are the result of different processing
requirements. Highly varying water use in plants within the same
subcategory is the result of varying in-plant operating
practices.
The chemicals used in processing plants (i.e., preservatives,
cure, pickle, and detergents) are not useful as a basis for
subcategorization. Differences in waste load that may be caused
by chemicals are the result of different operating practices.
Fuels are usually natural gas or fuel oil. They have no effect
on categorization.
Plant Size
The plant size distribution in the meat processing industry might
be fairly approximated by the distribution of the sample of
plants that responded to the survey questionnaire. This size
distribution of the study sample is presented in Table 3. The
distribution is approximately bi-modal with the median of the
small plants at about 950 kg (21CO Ib) per day and the median of
the large plants at about 34,500 kg (75,000 Ib) per day. Thus,
there was found to be a very real and distinct separation of the
industry into two general plant sizes—small and large—with the
typical large plant being about 35 times larger than the typical
small plant. In addition, the waste water flow from the typical
41
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PO
Q_
a.
en
^
in
o
o
ffl
o>
o
_J
UJ
H
i
I
tr
24
22
20
18
16
14
12
10
e
6
4
2
0
-
-
-
-
-
-
-
-
-
-
-
I [
SMALL MEAT
PROCESSORS CUTS
ONLY
SAUSAGE
LUNCHEON
MEATS
HAM
PROCESSING
CANNED
MEATS
Figure 6. Raw Waste Load Variations by Subcategory
-------
large plant is more than 100 times that from a small plant. This
information clearly lends credence to the subcategorization by
size.
The maximum production level for the small processor subcategory
was set in the middle of the range between the highest recorded
production level for a small processor—2300 kg (5000 Ib) per
day—and the lowest output for large processors, 3400 kg (7500
Ib) per day. The production data is from the North Star survey
questionnaire. There is a very obvious gap in the output of
plants between 2300 and 3400 kg per day (5000 to 7500 Ib).
There can be an enforcement problem posed by the plant with an
output slightly greater than the dividing line, wherever it is
set. The middle part of the range of output with no recorded
plants was selected to minimize this problem. Presuming the data
is representative, there should be fewer plants in the industry
close to or just exceeding this dividing line between large and
small processors by the choice of 2730 kg (6000 Ib) per day.
Table 3. Plant Size Distribution of Meat Processing
Plants That Returned Survey Questionnaires
Plant Size
kg/day
Less than 2750
2301-4000
4601-23,000
23,001-46,000
46,001 and
larger
Ib/day
Less than 6000
6001-10,000
10,001-50,000
50,001-100,000
100,001 and
larger
Number
of Plants
85
6
17
18
22
Percent
of Total
57.4
4.0
11.5
12.2
14.9
Cummulative
Percent
57.4
61.4
72.9
85.1
100.0
The production and waste water differences between the small and
large plants are reflected in the raw waste load and in the type
waste water treatment used by the respective groups. This is
of
the critical test in determining the utility of a
factor, and plant size obviously meets the test.
categorization
All ten of the small plants that reported on-site treatment of
their own waste water use septic tanks and subsoil seepage
systems and thus have a "no-discharge" type of treatment. The
small waste water quantity allows these plants to use this
treatment technique effectively.
Raw waste data are not generally available for small plants.
North Star sampled the waste water from two such plants, and the
average BOD5 was found to be 1.06 kg per kkg (1.06 Ib per 1000
Ib) FP. This, in comparison with the average for the large
plants of 5.2 kg per kkg (5.2 Ib per 1000 Ib) FP firmly
substantiates the selection of plant size as a valid basis for
categorization.
43
-------
Age and Location
Processing plant age and location are not meaningful factors for
deriving segmentation of the industry. Neither information from
this study nor that from previous studies reveals any discernible
relationship between these factors and effluent quality or any
other basis for categorizing.
Age as a factor might be expected to be at least amenable to
quantitative identification and interpretation, but unfortunately
age does not even achieve that degree of usefulness. The meat
processing industry, like the meat packing industry, is
relatively old, and some old plants incorporate early operating
ideas and practices. Some plants, on the other hand, are very
new and incorporate the latest operating ideas and practices.
Nevertheless, most older plants have been updated by internal
changes in processes and equipment. Therefore, to say that a
plant was built 50 years ago and is 50 years old is not
particularly meaningful in terms of interpreting plant practices.
In addition, no consistent pattern between plant age and raw
waste characteristics was found.
Examination of the raw waste characteristics relative to plant
location reveals no apparent relationship or pattern.
44
J
-------
SECTION V
WATER USE AND WASTE CHARACTERIZATION
WASTE WATER CHARACTERISTICS
Water is used in the meat processing industry as a product
ingredient; to cleanse, cure, cook, and cool products; to remove
and convey unwanted material from equipment and process areas;
and to heat or cool operating equipment. The principal
operations and processes in meat processing plants where waste
water originates are;
o Meat materials preparation
o Pickling
o Product cooking and cooling
o Canning
o Cleanup
o Plant and equipment cooling.
Waste waters from meat processing plants contain organic matter
(including grease") , suspended solids, and inorganic materials
such as phosphates, nitrates, nitrites, and salt. These
materials enter the waste stream as meat and fatty tissue, meat
juices, product spills and losses, curing and pickling solutions,
preservatives, and caustic or alkaline detergents.
Raw Waste Characteristics
The raw waste load from all subcategories of the meat processing
industry discussed in the following paragraphs includes the
effects of in-plant materials recovery (primary waste treatment).
The parameters used to characterize the raw effluent are flow,
BOD5, suspended solids (SS), grease, chlorides, phosphorus, and
Kjeldahl nitrogen. As discussed in Section VI, BOD5 is
considered to be, in general, the most representative measure of
the raw waste load. The parameter used to characterize the size
of the operations is the amount of processed meat products
produced. All values of the waste parameters are expressed as
kg/kkg of finished product (FP), which has the same numerical
value as lb/1000 Ib FP. In some cases; certain waste components
in effluents are diluted so that concentration becomes the more
significant measure of waste load. In these cases, concentration
is reported as mg/1, which is equivalent to parts per million.
The quantity of processed meat products or finished products is
reported in kg/day and waste water flow is reported in liters/kkg
FP.
45
-------
The data used to compute the values presented in Tables 4 through
8 were obtained through questionnaires distributed to members by
the major trade associations—the American Meat Institute, the
National Independent Meat Packers Association, the Western States
Meat Packers Association, and the American Association of Meat
Processors, formerly the National Institute of Locker and Freezer
Provisioners; through data provided directly by companies; and
through data obtained from state and municipal pollution control
agencies and sewer boards, and the Environmental Protection
Agency. Some information on the amount and type of processed
products for specific plants was obtained from the U.S.
Department of Agriculture. Survey questionnaire information was
collected on 148 identifiable plants. Data on 38 of these plants
were useful in categorization and in characterization of the raw
waste and waste treatment practices. Information found in the
open literature was not detailed enough to be included.
A summary of data including averages, standard deviations,
ranges, and number of observations (plants) is presented in the
following sections for each of the five subcategories of the
industry. These subcategories are:
1. Small processors
2. Meat cutters
3. Sausage and luncheon meat processors
4. Ham processors
5. Meat canners.
A detailed description of the subcategories was presented in
Chapter IV.
Small Processors
The small processor may produce a wide range of products, but in
small quantities, 2730 kg (6000 Ib) per day or less. Most of the
plants in the study sample prepared fresh meat cuts. Fresh
sausage was the second most frequent product, followed by a few
plants that produced hams or wieners, usually in addition to the
meat cuts and sausage. The waste water flow originates
predominately from cleanup. The scale of production and the
typically limited finished product mix precluded the need for
substantial quantities of water during the production day.
Cleanup generates the major portion of waste water in a small
processing plant—on the order of 50 to 90 percent of the total
waste water flow. Table 4 summarizes the pertinent data
collected in this subcategory.
Meat Cutters
The large processor that produces only meat cuts as a finished
product requires virtually no process water, and thereby
generates a waste water stream primarily during cleanup. A plant
in this subcategory uses manual labor to break, trim, and cut the
46
-------
Table 4. Raw Waste Characteristics of
Small Processors
Parameter
Production
Waste water
flow
BOD
Suspended solids
Grease
COD
Total volatile
solids
Total dissolved
solids
Kjeldahl nitrogen
Ammonia
Nitrates
Nitrites
Chlorides
Total phosphorus
Total coliform
no./ 100 ml
Fecal coliform
no./ 100 ml
Average'
950 kg/day
(2100 Ib/day)
3335 1/kkg FP
(400 gal./lOOO Ib)
1.06 kg/kkg FP
0.80 kg/kkg FP
0.49 kg/kkg FP
1.87 kg/kkg FP
1.62 kg/kkg FP
1.84 kg/kkg FP
(3990 mg/1)
200 mg/1
68 mg/1
11.8 mg/1
2.1 mg/1
1060 mg/1
68 mg/1
—
0.6 MM
Range
140-2300 kg/day
83-25,000 1/kkg
0.99-1.1 kg/kkg
0.73-0.86 kg/kkg
0.45-0.53 kg/kkg
1.7-2.05 kg/kkg
1.5-1.74 kg/kkg
1.57-2.1 kg/kkg
40-360 mg/1
24-113 mg/1
7. 2-16. 4 mg/1
0.24-4.0 mg/1
433-1060 mg/1
40-96.2 mg/1
0.75 MM &
36 MM
0.31 MM &
0.89 MM
Number of
Observations
85
81
2
2
2
2
2
2
2
2
2
2
2
2
2
2
47
-------
large meat parts into single-portionmeat cuts. Very little
equipment, other than saws and knives, comes in contact with the
meat products. The relative simplicity of operation and
equipment results in small quantities of process water and a
small waste load in the cleanup water. The raw waste and related
data are summarized in Table 5.
Sausage and Luncheon Meat Processors
This subcategory of the industry tends to be quite similar to the
small processor, but with a slightly expanded product mix and
substantially higher production rates and waste water flows. The
expanded product mix tends to include products requiring more
intensive processing. Higher product rates tend to result in
higher water use; however, there is no reliable quantitative
relationship between normalized waste water flow and production
quantity. This is true for all subcategories. The data on the
plants that are large processors but produce no hams or canned
products are listed in Table 6.
Ham Processors
This subcategory includes the large processing plants that
produce hams as their only product and plants that produce hams
and any combination of other products, particularly cured
products. The operations involved in ham production use more
water than the typical meat processing operations; and because of
the direct water-ham contact, the waste water load is increased.
The production operations and cleanup in the rest of the
processing plant is,fairly comparable in practice and resulting
waste load to that of the previous subcategory. As indicated by
the data in Table 7, the plants in this subcategory tend to be
somewhat smaller, but have a higher normalized waste water flow
than the large sausage and luncheon meat plants (those that
produce no hams or canned products).
Meat Canners
The large processors that produce canned meat products are, on
the average, the larger plants in the industry with the highest
normalized waste water flow. Some plants produce only canned
products, while some produce a full line of processed meat
products. Canning involves a number of processing operations
unique to this subcategory of the industry. These operations
require special equipment and generate normalized waste water
flows greater than other meat processing operations.
The increased water use occurs during both production and
cleanup. In addition, preparation of the meat products to be
canned will usually require a number of processing steps such as
48
-------
Table 5. Raw Waste Characteristics of
Meat Cutter Subcategory
Parameter
Production
Waste water
flow
BOD5
Suspended
solids
Grease
COD
Total volatile
solids
Total dissolved
solids
Kjeldahl
nitrogen
Ammonia
Nitrates
Nitrites
Chlorides
Total
phosphorus
Total coliform
(no./lOO ml)
Fecal coliform
(no./lOO ml)
Average
63,000 kg/day FP
(138,000 Ib/day)
600 1/kkg FP
(72 gal./ 1000 Ib)
0.52 kg/kkg FP
0.64 kg/kkg FP
0.12 kg/kkg F?
0.29 kg/kkg FP
0.23 kg/kkg FP
0.26 kg/kkg FP
(1204 mg/1)
5.0 mg/1
1-. 3 mg/1
0.88 mg/1
0.04 mg/1
162 mg/1
8.42 mg/1
46.5 MM
0.44 MM
Range
6400-158,000 kg/day
175-3635 1/kkg
0.23-1.09 kg/kkg
0.34-0.94 kg/kkg
0.066-0-17 kg/kkg
—
—
—
—
—
—
—
—
—
—
,
—
Numbe:.
Observa;
6
6
2
2
2
1
1
1
1
1
1
1
1
1
1
1
49
-------
Table 6. Raw Waste Characteristics of
Sausage and Luncheon Meats
Processor Subcategory
Parameter
Production
Waste water
flow
BOD
Suspended
solids
Grease
COD
Total volatile
solids
Total dissolved
solids
Kjeldahl
nitrogen
Ammonia
Nitrates
Nitrites
Chlorides
Total
phosphorus
Total coliform
(no./lOO ml)
Fecal coliform
(no./lOO ml)
Average
48,000 kg/day FP
(105,000 Ib/day)
9600 1/kkg FP
(1150 gal./lOOO Ib)
2.65 kg/kkg FP
3.46 kg/kkg FP
1.22 kg/kkg FP
4.6 kg/kkg FP
3.9 kg/kkg FP
12.6 kg/kkg FP
(1147 mg/1)
26.7 mg/1
1.52 mg/1
1.14 mg/1
0.3 mg/1
464 mg/1
18.2 mg/1
—
—
Range
3500-227,000 kg/day
1084-26,100 1/kkg
0.5-5.4 kg/kkg
0.12-12.0 kg/kkg
0.01-3.86 kg/kkg
0.85-9.8 kg/kkg
0.28-16.1 kg/kkg
0.65-57.7 kg/kkg
6.2-90.9 mg/1
0.14-3.56 mg/1
0.018-3.3 mg/1
0.001-1.05 mg/1
29-1320 mg/1
0.8-40.9 mg/1
—
—
Number of
Observations
22
19
12
14
13
8
8
8
7
7
5
4
8
7
0
0
50
-------
Table 7. Raw Waste Characteristics of
Ham Processor Subcategory
Parameter
Production
Waste water
flow
BOD
Suspended
solids
Grease
COD
Total volatile
solids
Total dissolved
solids
Kjeldahl
nitrogen
Ammonia
Nitrates
Nitrites
Chlorides
Total
phosphorus
Total colifora
(no./lOO ml)
Fecal coliform
(no./lOO ml)
Average
33,000 kg/day FP
(73,000 Ib/day)
10,600 1/kkg FP
(1270 gal./ 1000 lb)
5.5 kg/kkg FP
3.28 kg/kkg FP
2.37 kg/kkg FP
12.9 kg/kkg FP
8.2 kg/kkg FP
31.4 kg/kkg FP
(1938 mg/1)
21.4 mg/1
1.52 mg/1
2.07 mg/1
0.82 mg/1
758 mg/1
27.2 mg/1
22 MM
0.38 MM
Range . •. ---
3600-227,000 kg/day
288-29,200 1/kkg
0.24-16.2 kg/kkg
0.15-9.45 kg/kkg
0.08-5.4 kg/kkg
1.06-32.1 kg/kkg
0.88-14.6 kg/kkg
2.4-110 kg/kkg
9.7-45.1 mg/1
0.97-3.06 mg/1
1.01-4.33 mg/1
0.01-2.89 mg/1
414-1400 mg/1
8.4-64 mg/1
0.07MM-63MM
100 - 1.6 MM
21
14
18
16
12
9
7
6
6
6
7
10
7
4
5
51
-------
size reduction, mixing and blending, and cooking. The data on
raw waste, production, and waste water flow are summarized in
Table 8.
Discussion of Raw Wastes
The data in Tables 4 through 8 cover a waste water flow range of
600 to 11,250 liters per kkg FP (72 to 1350 gal. per 1000 Ib FP) ;
a waste load range of 0,52 to 11.9 kg BOD5/kkg FP (0.52 to 11.5
lb/1000 Ib FP); and a production range of 0.95 to 80.8 kkg FP/day
(2.1 to 178 thousand Ib/day). A comparison of the data shows
that the averages of the waste parameters are higher for the more
complex plants. This substantiates the basis for the
categorization of the industry. It should also be noted that
large size alone does not result in higher waste loads. Product
mix does affect the waste load.
Some variations in waste water flow and loading within any one of
the five subcategories can be attributed to differences in in-
plant processing techniques, product mix, building and equipment
cooling, and effectiveness of materials recovery in primary waste
treatment. Increased water use generally results in increased
raw waste load, on a normalized basis. The effect of waste water
flow on waste load is discussed in more detail later in this
section.
In the four large-processor subcategories, correlation analysis
of the data revealed that the raw BOD5 waste load correlates with
suspended solids, with grease, and with Kjeldahl nitrogen on a
normalized basis. This means that an increase (or decrease) in
BOD5 will be accompanied with a certain predictable increase (or
decrease) in the other parameter.
The effect of plant size, as measured by output of finished
product, on waste water generation and waste load was analyzed
for each subcategory by the use of correlation and regression
analysis. No statistically significant relationship was found in
any subcategory. Waste water volume and raw waste load both
varied widely at the same level of production. There also was no
consistent pattern of increase or decrease at different
production levels. This suggests that in-plant practices and
controls are the controlling factors in waste water and waste
load generation.
Data in Tables 4 through 8 show that there are far less data
available for the waste parameters other than BOD5, suspended
solids, and grease. Thus, conclusions regarding these parameters
are more tentative, but they are of value. The data on all waste
parameters reflects the impact on the raw waste load of the in-
plant operating techniques and housekeeping practices employed by
specific plants. This is one reason for the variation in waste
load within each subcategory. However, the data confirm some
relationship of waste load to product mix, particularly for
specific products such as hams and canned meat products.
52
-------
Table 8. Raw Waste Characteristics of
Meat Canner Subcategory
Parameter
Production
Waste water
flow
BOD
Suspended
solids
Grease
COD
Total volatile
solids
Total dissolved
solids
Kjeldahl
nitrogen
Ammonia
Nitrates
Nitrites
Chlorides
Total
phosphorus
Total coliform
(no./lOO ml)
Fecal coliform
(no./lOO ml)
'
Average
81,000 kg/day FP
(178,000 Ib/day)
11,250 1/kkg FP
(1350 gal./lOOO Ib)
11.5 kg/kkg FP
4.54 kg/kkg FP
2.08 kg/kkg FP
27.4 kg/kkg FP
17.0 kg/kkg FP
23.2* kg/kkg FP
(1524 mg/1)
40.0 mg/1
6.6 mg/1
0.04 mg/1
0.14 mg/1
13.5 & 138 mg/1
82.5 mg/1
0.56 MM
0.012 MM
Range
33,000-204,000 kg/day
3170-20,375 1/kkg
0.8-24 kg/kkg
0.46-11.5 kg/kkg
0.42-7.68 kg/kkg
16.6-38.3 kg/kkg
5.1-28.8 kg/kkg
—
—
—
—
—
—
—
—
—
Number of
Observations
9
8
8
9
7
2
2
1
1
1
1
1
2
1
1
1
53
-------
The average normalized raw waste load for every reported
pollutant in the meat cutter subcategory was lowest of the entire
industry. The small meat processor subcategory had an average
raw waste load that was second lowest in the industry for every
pollutant except nitrates. The number of plants in the sample
was small for both meat cutters and small processors. However,
low waste loads were expected from the production of a product
such as meat cuts, and from the scale of production and water use
in small processors; the data confirm these expectations.
The impact of ham processing was found to be manifest as an
increase in the average normalized waste load of the pollutants
in waste water from plants in the ham processing subcategory in
comparison with otherwise comparable plants that produce no hams
(sausage and luncheon meat subcategories). This higher waste
load occurs in spite of the fact that the sausage and luncheon
meat plants are larger and generate more waste water, on the
average, than the ham processing plants. The largest effect of
ham processing, however, is observed in the nitrates, nitrites,
dissolved solids (including salt), and Kjeldahl nitrogen content
of the raw waste. Nitrates, nitrites, and salt are used in
curing and pickling solutions.
The meat canners have the largest plants and produce the most
waste water in the industry. The canners have the highest
average normalized waste loading except in grease and in those
components used in curing and pickling. The average grease load
in the canners1 waste water is slightly less than that from the
ham processors. This might be explained by the canners1 practice
of cooking the meat materials before extensive handling. The
fats and grease from the cooking operation are confined and
collected for rendering and thereby are kept out of the sewer.
Process Waste Water Flow Diagrams
The origin and estimate of relative process waste water quantity
is indicated for each of three general product groups in Figures
7, 8, and 9. The waste water from cleanup, which is almost
always the largest and strongest waste load, is not indicated in
these figures because cleanup involves virtually the entire
processing plant, with the exception of the freezer areas, and
the cleanup waste water follows the same path through the plant
as the process waste water.
The sources and relative quantities differ for each group.
However, the materials recovery in a catch basin, sometimes
preceded by a static or vibrating screen, is typically the same
throughout the industry. There may be no recovery facilities in
the plants; this usually occurs only in plants which discharge to
a municipal sewer. Based on the survey questionnaire results, a
rough estimate would be that about one-third of all plants in the
industry have a materials recovery catch basin or the equivalent.
54
-------
RECEIVING,
STORAGE
THAWING
SM
BREAKING,
CUTTING, ETC.
SM
BATCHING
SM-small volume
MED-medium volume
LGE-large volume
V SM-very small volume
SM
GRINDING, MIXING,
EMULSIFICATION
SM-MED,
FORMING, STUFFING.
EXTRUDING
PERIODIC
SM
COOKING,
SMOKING
BRINE
PREPARATION
SM-MED-LGE.
PRODUCT
COOLING
LGE
MED-LGE^
_L
HOLDING,
PEELING
PERIODIC
SM
PACKAGING
FINISHED PRODUCT
STORAGE, SHIPPING
PLANT UTILITIES
SCREENS
PROCESS
WASTE
WATER
CATCH BASIN
SM-MED-LGE
SANITARY SEWER
TO SECONDARY
.-TREATMENT
•^AND DISCHARGE
OR
CITY SEWER
SOLIDS TO
DISPOSAL
Figure 7. Process Waste Water Flow—
Cut Meats and Comminuted Meats
55
-------
RECEIVING,
STORAGE
jl
THAWING
LGE.
TEMPERING
LGE
TRIMMING,
BONING
PICKLE
PREPARATION
SM
PICKLE APPLICATION
PRODUCT
COOLING
HOLDING,
SLICING
PACKAGING
FINISHED PRODUCT
STORAGE, SHIPPING
PLANT
UTILITIES
SANITARY
SEWER
MED-LGE
MED-LGE
COOKING,
SMOKING
PERIODIC
SM
SCREENS
- CATCH BASIN
SM-MED-LGE
PROCESS
WASTE
WATER
(SOLIDS TO
DISPOSAL
TO SECONDARY
t TREATMENT
*)AND DISCHARGE
OR
CITY SEWER
SM-small volume
MED-medium volume
LGE- large volume
V SM-very small volume
Figure 8. Process Waste Water Flow—
Hams and Bacon
56
-------
Figure 9. Process Waste Water Flow — Canned Meats
RECEIVING,
STORAGE
CAN PREPARATION
a TRANSPORTATION
WATER COOUNG
TOWER a
CIRCULATION
SYSTEM.
STORAGE,
SHIPPING
SM-small volume
MED-medium volume
LGE- large volume
V SM-very small
volume
INGREDIENT
PREPARATION
BATCHING
FILLING
RETORT
PRODUCT
COOLING
LABELING,
PACKAGING
PLANT
UTILITIES
SCREENS
CATCH BASIN
SM-MED-LGE
SANITARY
SEWER
'SOLIDS TO
^DISPOSAL
SM-MED
SM-MED
SM-MED
MED-LGE
SM
V SM
PROCESS
WASTE
WATER
TO SECONDARY
(TREATMENT
T*1AND DISCHARGE
OR
CITY SEWER
57
-------
The other options available to the industry are also indicated in
these figures. The plant utilities waste water may by-pass the
catch basin and, if the water is noncontaminated, it should also
by-pass secondary treatment. The dilution and increased volume
of waste water only serves to inhibit secondary treatment
effectiveness. The sanitary sewage always enters the waste water
downstream from the catch basin.
Those operations using recycled water, brine solutions, or pickle
solution are indicated in the figures. Some include periodic
dumping of the entire batch of a solution when it is contaminated
to a certain point, usually set by management in accordance with
government standards.
WATER USE - WASTE LOAD RELATIONSHIPS
Increased water use is usually associated with increased raw
waste load of pollutants within subcategories in the meat
processing industry. This was verified by regression and
correlation analyses of the data for each of the subcategories.
Figure 10 shows the average and range of results of regression
analysis on flow-waste load data for three subcategories among
the large processors, of the three lines presented in Figure 10,
only the sausage and luncheon meats line is statistically
substantiated with a correlation coefficient of 0.625 and 12
observations. The canned meats and ham processing lines are
based on 8 and 13 observations respectively and are line of sight
estimates, lacking rigorous statistical confirmation. However,
the generalized trend in these subcategories, as in the meat
packing industry, is for increased raw waste loading to occur as
waste water volume increases. For example, this figure clearly
illustrates that water use and waste load are closely related—
increased water use will increase the waste load by a fairly
predictable amount. For example, the figure shows that a 20
percent reduction in water use would, on the average, result in a
BOD5 reduction of 2.5, 1.0, and 0.5 kg/kkg FP (2.5, 1.0, and 0.5
lb/1000 Ib FP) for canned meats, ham processing, and sausage and
luncheon meats subcategories, respectively.
Further evidence for the dependence of pollutant waste load on
waste water flow is that, within the subcategories, the plants
with the lowest waste load had normalized waste water flows lower
than the average for the subcategory.
Low water use, and the correspondingly low waste load, requires
good in-plant water management practices. For example, a meat
cutting plant with a water use of 209 liters/kkg FP (26 gal./lOO
Ib FP) had a raw waste BOD5 of 0.25 kg/kkg FP (0.25 lb/1000 Ib
FP) in comparison with the subcategory average of 0.52 kg/kkg FP.
The same is true for the canners, the ham processors, and the
sausage and luncheon meat subcategories. Low waste water flow
and low pollutant waste load do occur together. The cause and
58
-------
20
Q.
\±-
15
CANNED MEATS
Ol
in
o
o
CD
o
§
UJ
-------
effect relationship is reasonable and there is a definite
empirical relationship as indicated in Figure 10-
SOURCES OF WASTE WATER AND WASTE LOAD
Meat Materials preparation
This group of operations in a meat processing plant includes all
of the handling and preparation of meat materials from receiving
and storage of raw materials through each processing step to
stuffing, extruding, or molding of processed meat products in
preparation for cooking, A large quantity of highly contaminated
waste water is generated by thawing frozen raw materials by
immersion in cool water. Substantial quantities of water are
required and the direct contact between the water and the meat
material results in a high waste load in this water. One study
of this pollution source concluded that slow freezing of hams
ruptures some of the cells and thawing drains the water and
juices resulting from the ruptured cells,* The waste includes
meat and fat tissue, dissolved salts, and nitrogenous materials.
Hams are frequently thawed by immersion and because of the high
volume of ham production in the industry a substantial waste load
results from this practice.
The breaking, cutting, trimming, and boning of meat materials in
preparation for further processing requires very little water and
generates very little waste load. Referring to the meat cutter
category as an example of the waste load from these operations,
the water use per kkg of FP is only 600 liters (72 gal./lOOO lb),
including cleanup. The BOD5 raw waste loading averages 0.52
kg/kkg FP (0,52 Ib/lQCO lb FP)7 Tempering a raw material by
immersion in water does not require as much water as wet thawing;
however, the waste load is similar.
The waste load in a meat processing plant originates primarily
from the cleaning of the equipment used for grinding, mixing,
blending, and emulsifying the materials for processed meat
products. Water is used to clean the carts that are used to move
the materials from one size reduction station to another in the
"sausage kitchen" area of a meat processing plant. Changing from
the production of one product to another may also require a
superficial cleaning of a piece of equipment during the operating
day.
The size reduction, and hence equipment use, depends on the type
of product ranging from a coarse grind in a product such as ham-
burger to the emulsion used in wiener manufacturing. The reduced
size of the meat materials results in more spillage and easier
disposal into the sewer in washing down the equipment and
processing areas. The frequent handling and movement of the
materials from one station to another also creates the
opportunity for spillage and for additional contact of the
product materials with equipment surfaces, thereby generating
additional waste loads.
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The final group of operations in materials preparation that
generate waste water and a waste load includes the processing
steps that involve the forming or the containerization of the
product mixture just prior to cooking; i.e., the extrusion,
stuffing, or molding operations. These operations follow size
reduction; therefore, any contamination of this equipment by the
comminuted product mixture will be similar to that from the size
reduction equipment. Waste water originates from these
operations primarily in the cleanup of the equipment. Some water
is used in preparing natural casings and in cleaning the molds
used in luncheon meat manufacturing.
The actual extrusion or stuffing of the product mixture into the
casings or molds involves feeding the product mixture through
equipment to fill the containers or casings. All of this
equipment is thoroughly coated with product mixture wherever the
mixture contacts the equipment, whenever a product change occurs
during the operating day, this equipment must be cleaned. As
with all other processing equipment, it is disassembled and
thoroughly cleaned after every processing day. Cleanup is the
largest source of waste water and waste load from the extrusion
and stuffing operations.
Pickling
The pickling or curing solution is a water solution containing
table salt, sugar-, and other chemicals including nitrites. It is
the primary source of salt and nitrite chemicals in the raw
waste. The sugar content of the solution also contributes to the
BOD5 loading of the waste water. The pickling solution is
frequently prepared at a location remote from the point of use of
the solution in the processing plant. The solution is prepared
in stainless steel tanks with mixers and pumps and it is stored
in these tanks for subsequent use in the pickling of hams, bacon,
and other products. It is general practice to reuse pickling
solution after it has been in contact with meat materials by
screening prior to reuse. The total quantity of pickling
solution is dumped periodically, ranging from once per day to
once per week, depending on in-plant practice and on the rate of
accumulation of contaminants.
Pickle solution is applied or injected in the production of hams,
bacon, and related cured products. The typical method of
injection of pickle solution into these products is by the
penetration of a bank of hollow needles through which the pickle
solution is pumped into the meat product. The products are
usually "pumped" with pickle to a point where the pickle oozes
out of the meat product when the needles are withdrawn. In
addition, particularly in bacon production, a substantial
quantity of solution simply runs off the product as it is hanging
on a hanger or "tree" prior to further processing. After
injection or application of pickle, it is common practice to hold
the hams or bacon slabs in a vat or cart with a covering of
pickling solution.
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The drippings from the pickle injection or application equipment
are substantial. Most of this equipment is designed to collect
the excess pickle after injection of each piece of meat and reuse
that pickling solution in subsequent injections or applications.
However, the solution remaining in the injection equipment is
dumped at the end of every processing day.
Also, the entire amount of pickling solution used as cover pickle
is dumped directly into the sewer from the tub when the hams or
bacon are to be further processed. The same type of tub is also
used without cover pickle to hold the hams. Excess pickle
solution and meat juices are squeezed from the hams because of
the weight of other hams piled one on another in the tub. All of
this liquid is dumped into the sewer when the hams are to be
processed further.
The hams or bacon are also taken from the pickle pumping
equipment and hung on "trees" that are designed to hold a number
of bacon slabs or hams for transport and holding in the smoke-
house or oven. Drippings from the hanging hams and bacon also
result in pickle solution and meat juice contamination of the
floor area under the "trees." These floor areas that are
frequently contaminated with liquids tend to become slippery and
require frequent washing or hosing down during the processing day
as a safety measure. This results in a waste load being washed
directly to the sewer.
Product Cooking and Cooling
Processed meat products are cooked in one of two types of cookers
that are in general use in the industry. The products are cooked
in gas-fired hot air ovens or steam coil heated ovens, also
called smokehouses, and in wet cookers using live steam or hot
water. Cooking and cooling of canned meat products are not
discussed in this section, but in the following section. Those
products that are prepared in stainless steel molds, such as
luncheon meats, are cooked in ovens that use live steam. This
live steam condenses and flows out as waste water. Molded
products are also cooked in hot water tanks which are open to the
atmosphere. In either case, the waste water from the cooking
operation has been in direct contact with the meat product
container. This container may be contaminated with grease on the
outside surfaces from contact with processing equipment. This
grease will contaminate the hot water used for cooking and be
dumped into the sewer. The waste load in this cooking water is
comparatively small. Cleanup of the wet cookers is minimal and
the waste water from cleanup has a very low waste content.
The smokehouse is one of the most common pieces of equipment in
the meat processing industry. It is used to cook a wide variety
of processed meat products. The oven is used for cooking,
smoking, and initial product cooling of meat products. The
cooking in this type of oven results in no immediate waste water
load. The grease generated in cooking and smoking, but washed
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into the sewer only during cleanup, can be minimized by low
temperature smoking at about 55°C (130°F) instead of the older
practice of smoking at high temperatures. The smoking operation
usually requires a small quantity of water in the smoke-
generating equipment to quench the sawdust after it has been
brought up to temperature for generating the smoke. The waste
water quantity from quenching is small; however, it may contain
suspended solids from the charred sawdust and also water-soluble
chemicals dissolved from the char.
Upon completion of the cooking and smoking, it is general
practice , to drench the products, other than hams and bacon, with
cold water or a cold brine solution, while still in the oven.
This is accomplished with water spray nozzles that are positioned
inside the oven to assure maximum coverage of the products with
water or brine. The cooling water is dumped directly to the
sewer. If a brine solution is used, the brine is collected and
reused for a period of time before dumping into the sewer. The
cooling water or brine comes in direct contact with the meat
product that has been cooked and with the wall and floor of the
oven, all of which are coated with juices, grease, and liquids
resulting from the cooking operation. All of these contaminants
of the cooling medium result in a waste load which is ultimately
dumped into the sewer.
In spite of the sprays that are used in processing the meat
products, the ovens accumulate a substantial quantity of buildup
on the walls, ceiling, and piping in the ovens. The ovens are
cleaned superficially once per day. However, a thorough cleaning
of all surfaces in an oven with highly caustic chemicals is done
as needed, usually once a week or more. In addition to the
materials resulting from cooking the meat products, a buildup of
the volatile components in the wood smoke occurs in the duct work
and the interior of an oven. The cleaning of an oven or
smokehouse generates a raw waste that contains grease, has a
somewhat higher pH because of the caustic materials in the
cleaning agents, and is very highly colored as a result of the
volatiles that have been deposited from the wood smoking
operation. Substantial quantities of water are required in the
oven cleaning process.
Canning
The preparation of a canned meat product in a meat processing
plant generates a large amount of water. The average total water
use in liters per day for the canning subcategory is double the
average of sausage and luncheon meat processors—the subcategory
with the next highest waste water volume. However, on a
normalized basis per kkg FP, the water use by canners is only
about 6.0 percent higher than ham processors who have the next
highest water use per unit of output. The raw waste load from
canning is much higher than for any other subcategory in the
industry, as previously indicated. The canning of a meat product
involves a processing sequence which can be described as a
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canning line. This line is a sequential step-wise processing
operation required for the preparation of a canned meat product.
The first step in this canning line involves washing and
sterilizing the cans, prior to filling. In addition, the can
preparation area is frequently located some distance from the
filling and closing operation and the cans are transported in
conveyors that are frequently lubricated with water.
Paralleling can preparation, the meat product is prepared for
canning in operations such as breaking, cutting, grinding,
cooking, etc,, which are similar to those used in preparation of
other meat products. In addition, canned meat products
frequently involve the use of sauces, gravies, or other mixtures
which are also prepared within the processing plant. The
preparation of these mixtures requires multiple handling of the
ingredients with the resulting spillage.
The meat product or meat product mixture which is to be canned is
prepared in batches comparable to the batching operation in
sausage making. The batches are prepared and held in vats. The
can and the meat product are brought together at the can-filling
step, which involves the use of high volume, high speed
equipment. The cans are usually sprayed with hot water or a
steam-water mixture just before the filling operation, and the
water is allowed to run directly to the floor and into the sewer.
The can-filling operation itself tends to be so fast that a
significant waste load is generated by the spills from the full
cans and from the filling machine itself. The closing of the
cans involves a final spray of steam into the can, followed by
immediate closing which creates the vacuum-packed type of canned
product. This spray also generates a small, but constant, waste
water stream.
The filled cans are placed in large portable baskets for heating
in retorts. The canned product is thoroughly heated within the
can in order to assure a sanitary product after the can filling
and closing. Retorting is usually done in a pressure vessel with
live steam which is constantly vented. The waste water generated
in retorting is not significant.
After the cans have been fully heated in the retort, they are
cooled by immersion in a large tank or container of cold water.
Movement of the cans and circulation of the water assures heat
transfer and cooling of the canned product. This water is
usually recirculated through cooling towers to maintain the
temperature and is not sewered nor otherwise disposed of. It,
therefore, generates essentially no waste water or waste load. A
small amount of fungicide is sometimes added to this water since
it is being recirculated for a long time. A small blowdown
quantity will enter the waste water stream and result in a very
low concentration of the fungicide chemical, if such a chemical
is being used.
The data on canning do not include any plants with an automated
high capacity canning line. The waste water volume per unit of
-------
production should
described above.
be less in this type of plant than in plants
The cleanup of canning equipment requires great quantities of
water to clean the numerous batching and mixing containers and
the can-filling equipment. The batching containers or vats
contain residual quantities of the canned meat product. In
addition, the pumping system and piping used to transport the
mixture to the can-filling equipment are also filled with
material. All of this residual material is washed directly from
the equipment into the sewer system.
The can-filling equipment may be cleaned with high pressure
steam. This results in the widespread dispersion of particles of
the product left on the can-^filling equipment. The residual
material is washed to the floor, and, usually, directly into the
sewer. Large quantities of water are also used in cleaning the
floors and walls in the processing and canning area. If dry
cleaning of the floors or manual cleanup of larger size particles
is not carried out prior to washdown, the raw waste load will be
substantially increased due to floor cleaning as well.
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SECTION VI
SELECTION OF POLLUTANT PARAMETERS
SELECTED PARAMETERS
Based on a review of the corps of Engineers Permit Applications
from meat processing plants, state and municipal sewer board and
pollution control administration data from various parts of the
country, industry data, survey questionnaire data, and data
obtained by sampling meat processing plant waste waters during
this study, the following chemical, physical, and biological
constituents are defined as pollutants in accordance with the
Act:
BOD5 (5-day, 20°C, biochemical oxygen demand)
COD (chemical oxygen demand)
Total suspended solids (TSS)
Total dissolved solids (TDS)
Oil and Grease
Total volatile solids (TVS)
Ammonia nitrogen
Kjeldahl nitrogen
Nitrates and nitrites
Phosphorus
Chlorides
Temperature
Fecal Coliform
pH, Acidity, Alkalinity
On the basis of all of the information considered, there is no
evidence of any purely hazardous pollutant (such as heavy metals
or pesticides) in the waste water discharged from meat processing
plants. On the basis of the amount and reliability of available
data, costs, and removal technology, effluent limitations have
been recommended only for the principal parameters BOD5, TSS, Oil
and grease, fecal coliforms, ammonia, phosphorus, and pH. Other
parameters are discussed because they are known to be in meat
processor waste waters and may be of environmental significance.
RATIONALE FOR SELECTION OF IDENTIFIED PARAMETERS
5-Day Biochemical Oxygen Demand (BOD5)
This parameter is an important measure of the oxygen consumed by
microorganisms in the aerobic decomposition of the wastes at 20°C
over a five-day period. More simply, it is an indirect measure
of the biodegradability of the organic pollutants in the waste.
BOD5 can be related to the depletion of oxygen in a receiving
stream or to the requirements for waste treatment. Values of
BOD5 range from 70 to 2900 mg/1 in the raw waste. However, the
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median value for the industry is between 350 and 500 mg/1 and the
typical range is from 200 to 1200 mg/1 of BOD5.
If the final effluent from a meat processing plant enters a
stream at too high a BOD5 level, it will reduce the dissolved
oxygen level in that stream to a level below that necessary to
sustain most fish life; i.e., below about 4 mg/1. Many states
currently restrict the BOD5 of effluents to below 20 mg/1 if the
stream is small in comparison with the flow of the effluent. A
limitation of 200 to 300 mg/1 of BOD5 is often applied for
discharge to a municipal sewer, and surcharge rates often apply
if the BOD5 is above the designated limit.
A 20-day biochemical oxygen demand (BOD20), sometimes called
"ultimate" BOD, is usually a better measure of the waste load
than BOD5. However, the test for BOD2J3 requires 20 days to run,
so it is an impractical measure for most purposes.
Correlation analysis of the data for each subcategory revealed a
high positive correlation between BOD5 and the grease content of
the raw waste. Data for the luncheon meat and sausage processors
and ham processors subcategories were sufficient to determine a
high positive correlation between BOD5 and COD, and BOD5 and
total volatile solids. Such correlations are useful in
identifying contributing factors in the raw waste load and in
relating known changes in waste loading by one contaminant to
predicted changes by another contaminant.
Biochemical oxygen demand (BOD) is a measure of the oxygen
consuming capabilities of organic matter. The BOD does not in
itself cause direct harm to a water system, but it does exert an
indirect effect by depressing the oxygen content of the water.
Sewage and other organic effluents during their processes of
decomposition exert a BOD, which can have a catastrophic effect
on the ecosystem by depleting the oxygen supply. Conditions are
reached frequently where all of the oxygen is used and the
continuing decay process causes the production of noxious gases
such as hydrogen sulfide and methane. Water with a high BOD
indicates the presence of decomposing organic matter and
subsequent high bacterial counts that degrade its quality and
potential uses.
Dissolved oxygen (DO) is a water quality constituent that, in
appropriate concentrations, is essential not only to keep
organisms living but also to sustain species reproduction, vigor,
and the development of populations. Organisms undergo stress at
reduced DO concentrations that make them less competitive and
able to sustain their species within the aquatic environment.
For example, reduced DO concentrations have been shown to
interfere with fish population through delayed hatching of eggs,
reduced size and vigor of embryos, production of deformities in
young, interference with food digestion, acceleration of blood
clotting, decreased tolerance to certain toxicants, reduced food
efficiency and growth rate, and reduced maximum sustained
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swimming speed. Fish food organisms are likewise affected
adversely in conditions with suppressed DO. Since all aerobic
aquatic organisms need a certain amount of oxygen, the
consequences of total lack of dissolved oxygen due to a high BOD
can kill all inhabitants of the affected area.
If a high BOD is present, the quality of the water is usually
visually degraded by the presence of decomposing materials and
algae blooms due to the uptake of degraded materials that form
the foodstuffs of the algal populations.
Chemical Oxygen Demand (COD)
COD is yet another measure of oxygen demand. It measures the
amount of organic plus some inorganic pollutants under a
carefully controlled direct chemical oxidation by a dichromate-
sulfuric acid reagent. COD is a much more rapid measure of
oxygen demand than BODjj, and is potentially very useful.
However, it does not have the same significance as a measure of
biodegradability and cannot be substituted for BOD5 because
COD:BOD,5 ratios vary with the type of waste constituents in a
waste stream. Thus a COD level is not included in the proposed
limitations. The COD range for meat processing plants is from
290 to 4600 mg/1 with the median for the industry between 500 and
800 mg/1.
COD provides a rapid determination of waste strength. Changes in
value can be used to indicate a serious plant or treatment
malfunction long before the BOD5 analysis can be run. A given
plant or waste treatment system usually has a relatively narrow
range of COD:BOD5 ratios, if the waste characteristics are fairly
constant. If so, processing plant operations relative to waste
load could be monitored on the basis of measured COD values. In
the meat processing industry, the normalized COD ranges from
about 3 to 1.8 times the normalized BOD5 with relatively little
change in this ratio beyond a BOD5 of 5 kg per kkg FP. This
ratio may have greater variability at low BODf> values for raw
wastes, and at high COD values following secondary treatment for
a given plant. This may occur because the readily degraded
material, as indicated by BOD5, will be reduced to very low
levels in secondary treatment.
Total Suspended Solids (TSS)
This parameter measures the suspended material that can be
removed from the waste waters by laboratory filtration; but it
does not include coarse or floating matter than can be readily
screened or settled out. Suspended solids are visually apparent
and a rapid measure of pollution. SS are also a measure of the
material that may settle in tranquil or slow-moving streams.
Suspended solids loadings per unit of production in the waste
from meat processing plants correlate very well with COD, but not
as well with BOD5. A high level of suspended solids is generally
an indication of high oxygen demand. The normalized suspended
solids range from about one-third to 1.5 times the normalized
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BODji values in the raw waste. The suspended solids
concentrations in the meat processing industry range from 70 to
1500 mg/1 and the industry median is between 250 and 350 mg/1.
Suspended solids measurement also provides an indication of the
effectiveness of solids removal systems such as clarifiers and
fine screens in waste treatment.
Suspended solids include both organic and inorganic materials.
The inorganic components include sand, silt, and clay. The
organic fraction includes such materials as grease, oil, tar,
animal and vegetable fats, various fibers, sawdust, hair, and
various materials from sewers. These solids may settle out
rapidly and bottom deposits are often a mixture of both organic
and inorganic solids. They adversely affect fisheries by
covering the bottom of the stream or lake with a blanket of
material that destroys the fish-food bottom fauna or the spawning
ground of fish. Deposits containing organic materials may
deplete bottom oxygen supplies and produce hydrogen sulfide,
carbon dioxide, methane, and other noxious gases.
In raw water sources for domestic use, state and regional
agencies generally specify that suspended solids in streams shall
not be present in sufficient concentration to be objectionable or
to interfere with normal treatment processes. Suspended solids
in water may interfere with many industrial processes and cause
foaming in boilers, or encrustations on equipment exposed to
water, especially as the temperature rises. Suspended solids are
undesirable in water for textile industries; paper and pulp;
beverages; dairy products; laundries; dyeing; photography;
cooling systems, and power plants. Suspended particles also
serve as a transport mechanism for pesticides and other
substances which are readily sorbed into or onto clay particles.
Solids may be suspended in water for a time, and then settle to
the bed of the stream or lake. These settleable solids
discharged with man"s wastes may be inert, slowly biodegradable
materials, or rapidly decomposable substances. While in
suspension, they increase the turbidity of the water, reduce
light penetration and impair the photosynthetic activity of
aquatic plants.
Solids in suspension are aesthetically displeasing. When they
settle to form sludge deposits on the stream or lake bed, they
are often much more damaging to the life in water, and they
retain the capacity to displease the senses. Solids, when
transformed to sludge deposits, may do a variety of damaging
things, including blanketing the stream or lake bed and thereby
destroying the living spaces for those benthic organisms that
would otherwise occupy the habitat. When of an organic and
therefore decomposable nature, solids use a portion or all of the
dissolved oxygen available in the area. Organic materials also
serve as a seemingly inexhaustible food source for sludgeworms
and associated organisms.
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Turbidity is principally a measure of the light absorbing
properties of suspended solids. It is frequently used as a
substitute method of quickly estimating the total suspended
solids when the concentration is relatively low.
Total Dissolved Solids (TDS)
The dissolved solids in the waste water are mainly inorganic
salts. The salt present in the largest amount is table salt
(sodium chloride). Loadings of dissolved solids in waste water
thus vary to a large extent with the amount of sodium chloride
entering the waste stream. In the meat processing industry the
raw waste range of dissolved solids concentration is from 76 to
2900 mg/1 and the industry median is between 800 and 1200 mg/1.
The range of sodium chloride percent in the dissolved solids is
from 14 to 44 percent, increasing as the normalized dissolved
solids loading increases.
Another salt sometimes present in significant quantities is
sulfate. This may come from sulfate in the incoming raw water,
or perhaps from water conditioning treatment of the water supply.
Sulfates become particularly troublesome in causing odor in
anaerobic treatment systems, where they are converted to
sulfides.
Dissolved solids in the final effluent were at concentrations
between 1200 and 1800 mg/1 in the three plants reporting such
data. The dissolved solids are particularly important because
they are relatively unaffected by biological treatment processes
(except sulfates, as mentioned above). Therefore, unless
removed, they will accumulate on recycle or reuse of water within
a plant. Furthermore, dissolved solids at discharge
concentrations greater than 1500 mg/1 may be harmful to
vegetation and preclude various irrigation options. The
technology required for dissolved solids removal is uneconomical
for this industry and therefore no limitation has been proposed.
Oil and Grease
Grease, also called oil and grease, or hexane solubles, is a
major pollutant in the raw waste stream of meat processing
plants. Grease forms unsightly films and layers on water,
interferes with aquatic life, clogs sewers, disturbs biological
processes in sewage treatment plants, and can also become a fire
hazard. The loading of grease in meat processing raw wastes
varies from 15 to 560 mg/1. The variation in average loading in
the industry is from 0.12 to 222 kg per kkg FP. The industry
median grease concentration in the raw waste is about 120 mg/1.
As indicated earlier in this section, grease and COD correlate
very well and in a positive direction; i.e., increase for
increase. Thus, a change in one contaminant measure is a
reliable indication of a change in the other.
Grease may foul municipal treatment facilities, especially
trickling filters, and reduce their effectiveness to virtually
nil. Thus, it is of great interest and concern to municipal
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treatment plants when grease exceeds 100 mg/1 in
stream.
raw waste
Total Volatile Solids (TVS)
Total volatile solids are a rough measure of the total amount of
organic matter in the waste water. Specifically, they are the
total amount of combustible material in the dissolved solids and
suspended solids. Volatile solids in the raw waste waters of
meat processing plants vary from 170 to 1700 mg/1 with a median
of about 400 mg/1. The normalized loadings vary from 0.23 to 29
kg per kkg FP.
Oil and grease exhibit an oxygen demand. Oil emulsions may
adhere to the gills of fish or coat and destroy algae or other
plankton. Deposition of oil in the bottom sediments can serve to
exhibit normal benthic growths, thus interrupting the aquatic
food chain. Soluble and emulsified material ingested by fish may
taint the flavor of the fish flesh. Water soluble components may
exert toxic action on fish* Floating oil may reduce the re-
aeration of the water surface and in conjunction with emulsified
oil may interfere with photosynthesis. Water insoluble
components damage the plumage and costs of water animals and
fowls. Oil and grease in a water can result in the formation of
objectionable surface slicks preventing the full aesthetic
enjoyment of the water.
Oil spills can damage the surface of boats and can destroy the
aesthetic characteristics of beaches and shorelines. Volatile
solids correlate quite well with BOD5 and COD in the luncheon
meats and sausages and ham processing subcategories, where there
were sufficient data to ascertain this correlation. Total
volatile solids are relatively easy to determine in waste water
analysis; thus they can be used as a rapid method to determine a
serious plant or treatment system malfunction. The correlations
with BOD5 and COD are essential to this use of this parameter.
The BOD5 measure is inclusive enough to preclude the need for a
volatile solids limitation.
Ammonia Nitrogen
Ammonia nitrogen in raw waste is just one of many forms of
nitrogen in a waste water stream. Anaerobic decomposition of
protein, which contains organic nitrogen, leads to the formation
of ammonia. Thus, anaerobic lagoons or digesters produce high
levels of ammonia. Also, septic (anaerobic) conditions in traps,
basins, etc., may lead to ammonia formation in the waste water.
Another source of ammonia can be leakage of ammonia refrigeration
systems, which are common in meat processing plants.
Ammonia is oxidized by bacteria in a process called
"nitrification" to nitrites and nitrates, thus consuming the
available oxygen. This may occur in an aerobic treatment process
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or in a stream. Thus, ammonia will deplete the oxygen supply in
a stream and its oxidation products are recognized nutrients for
aquatic plant growth. Also, free ammonia in a stream is known to
be harmful to fish.
A typical or median concentration in meat processing raw waste is
about 1.5 mg/1 with an industry range of 0.5 to 28 mg/1.
However, after treatment in an anaerobic secondary treatment
system, the concentration of ammonia can reach as high as 100 to
200 mg/1, which is a serious limitation for anaerobic treatment
systems.
Ammonia is a common product of the decomposition of organic
matter. Dead and decaying animals and plants along with human
and animal body wastes account for much of the ammonia entering
the aquatic ecosystem. Ammonia exists in its non-ionized form
only at higher pH levels and is the most toxic in this state.
The lower the pH, the more ionized ammonia is formed and its
toxicity decreases. Ammonia, in the presence of dissolved
oxygen, is converted to nitrate (NO3) by nitrifying bacteria.
Nitrite (NO2), which is an intermediate product between ammonia
and nitrate, sometimes occurs in quantity when depressed oxygen
conditions permit. Ammonia can exist in several other chemical
combinations including ammonium chloride and other salts.
Nitrates are considered to be among the poisonous ingredients of
mineralized waters, with potassium nitrate being more poisonous
than sodium nitrate. Excess nitrates cause irritation of the
mucous linings of the gastrointestinal tract and the bladder; the
symptoms are diarrhea and diuresis, and drinking one liter of
water containing 500 mg/1 of nitrate can cause such symptoms.
Infant methemoglobinemia, a disease characterized by certain
specific blood changes and cyanosis, may be caused by high
nitrate concentrations in the water used for preparing feeding
formulae. While it is still impossible to state precise
concentration limits, it has been widely recommended that water
containing more than 10 mg/1 of nitrate nitrogen (NO3-N) should
not be used for infants. Nitrates are also harmful in
fermentation processes and can cause disagreeable tastes in beer.
In most natural water the pH range is such that ammonium ions
(NH4+) predominate. In alkaline waters, however, high
concentrations of un-ionized ammonia in undissociated ammonium
hydroxide increase the toxicity of ammonia solutions. In streams
polluted with sewage, up to one-half of the nitrogen in the
sewage may be in the form of free ammonia, and sewage may carry
up to 35 mg/1 of total nitrogen. It has been shown that at a
level of 1.0 mg/1 un^ionized ammonia, the ability of hemoglobin
to combine with oxygen is impaired and fish may suffocate.
Evidence indicates that ammonia exsrts a considerable toxic
effect on all aquatic life within a rau.ge of less than 1,0 mg/1
to 25 mg/1, depending on the pH and dissolved oxygen level
present.
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in use by the meat processing industry, and once in the waste
waters they are very costly to remove.
Temperature
Because of the long detention time at ambient temperatures in the
biological treatment systems used for treating meat processing
waste water, the temperature of the final effluent is virtually
the same as the temperature of the receiving body of water*
Thus, there is no need for a temperature limitation-
Noncontaminated cooling water is discharged at a maximum of 40°
to 43°C (105° to 11C°F) during the summer months, and is cooler
at other times of the year. The quantity of this cooling water
varies from small to large when compared with the process waste
water flow, depending on in-plant equipment and practices. The
temperature of the raw waste typically averages between 22°C
(70°F) and 32°C (90°F). These temperatures are an asset for
biological treatment of the waste, fostering high rates of growth
of the microorganisms needed for waste treatment.
Temperature is one of the most important and influential water
quality characteristics. Temperature determines those species
that may be present; it activates the hatching of young,
regulates their activity, and stimulates or suppresses their
growth and development; it attracts and may kill aquatic
organisms when the water becomes too hot or becomes chilled too
suddenly. Colder water generally suppresses development. Warmer
water generally accelerates activity and may be a primary cause
of aquatic plant nuisances when other environmental factors are
suitable.
Temperature is a prime regulator of natural processes within the
water environment. It governs physiological functions in
organisms and, acting directly or indirectly in combination with
other water quality constituents, it affects aquatic life with
each change. These effects include chemical reaction rates,
enzymatic functions, molecular movements, and molecular exchanges
between membranes within and between the physiological systems
and the organs of an animal.
Chemical reaction rates vary with temperature and generally
increase as the temperature is increased. The solubility of
gases in water varies with temperature. Dissolved oxygen is
decreased by the decay or decomposition of dissolved organic
substances and the decay rate increases as the temperature of the
water increases reaching a maximum at about 30°C (86°F). The
temperature of stream water, even during summer, is below the
optimum for pollution-associated bacteria. Increasing the water
temperature increases the bacterial multiplication rate when the
environment is favorable and the food supply is abundant.
Reproduction cycles may be changed significantly by increased
temperature because this function takes place under restricted
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temperature ranges. Spawning may not occur at all because
temperatures are too high. Thus, a fish population may exist in
a heated area only by continued immigration. Disregarding the
decreased reproductive potential, water temperatures need not
reach lethal levels to decimate a species. Temperatures that
favor competitors, predators, parasites, and disease can destroy
a species at levels far below those that are lethal.
Fish food organisms are altered severely when temperatures
approach or exceed 90°F. Predominant algal species change,
primary production is decreased, and bottom associated organisms
may be depleted or altered drastically in numbers and
distribution. Increased water temperatures may cause aquatic
plant nuisances when other environmental factors are favorable.
Synergistic actions of pollutants are more severe at higher water
temperatures. Given amounts of domestic sewage, refinery wastes,
oils, tars, insecticides, detergents, and fertili zers more
rapidly deplete oxygen in water at higher temperatures, and the
respective toxicities are likewise increased.
When water temperatures increase, the predominant algal species
may change from diatoms to green algae, and finally at high
temperatures to blue-green algae, because of species temperature
preferentials. Blue-green algae can cause serious odor problems.
The number and distribution of benthic organisms decreases as
water temperatures increase above 90°F, which is close to the
tolerance limit for the population. This could seriously affect
certain fish that depend on benthic organisms as a food source.
The cost of fish being attracted to heated water in winter months
may be considerable, due to fish mortalities that may result when
the fish return to the cooler water.
Rising temperatures stimulate the decomposition of sludge,
formation of sludge gas, multiplication of saprophytic bacteria
and fungi (particularly in the presence of organic wastes), and
the consumption of oxygen by putrefactive processes, thus
affecting the esthetic value of a watercourse.
In general, marine water temperatures do not change as rapidly or
range as widely as those of freshwaters. Marine and estuarine
fishes, therefore, are less tolerant of temperature variation.
Although this limited tolerance is greater in estuarine than in
open water marine species, temperature changes are more important
to those fishes in estuaries and bays than to those in open
marine areas, because of the nursery and replenishment functions
of the estuary that can be adversely affected by extreme
temperature changes.
Fecal Coliform
The coliform bacteria contamination of raw waste is substantially
reduced in the waste treatment systems used in the industry.
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SECTION VII
CONTROL AND TREATMENT TECHNOLOGY
SUMMARY
The waste load discharged from the meat processing industry to
receiving streams can be reduced to desired levels, including no
discharge of pollutants, by conscientious water management, in-
plant waste controls, process revisions, and by the use of
primary, secondary and tertiary waste water treatment. Figure 11
is a schematic of a suggested waste reduction program for the
meat processing industry to achieve a high quality effluent.
This section describes many of the techniques and technologies
that are available or that are being developed to achieve the
various levels of waste reduction. In-plant control techniques
and waste water management suggestions are described first.
Waste treatment technology normally used as a primary treatment
is then described. In the case of the meat processing industry,
this "primary" treatment is a materials recovery process, and is
considered as part of the in-plant system, although many of these
systems have been improved to reduce pollution levels. The
effluent from primary treatment is considered the "raw waste."
Secondary treatment systems are used in the treatment of the raw
waste.
This section presents a description of each treatment process,
the specific advantages and disadvantages of each system, and the
effectiveness on the specific waste water contaminants found in
meat plant waste. Much of the information on waste treatment
effectiveness for meat processing waste water is based on
information on meat packing plant waste treatment systems
collected by North Star in a study of the red meat industry for
the EPA.9 This was necessary because of the very small number of
meat processing plants with their own waste treatment systems and
the paucity of data. The inference regarding the applicability
of meat packing practices to meat processing waste treatment was
justified in that the waste water from plants in the two groups,
meat processor and packer, was similar, except for the typically
lower water volume and lower concentration of some pollutants for
the processor.
The tertiary and advanced treatment systems that are applicable
to the waste from typical processing plants are described in the
last part of this section. some of these advanced treatment
systems have not been used in full scale on meat packing or
processing plant waste; therefore, the development status,
reliability, and potential problems are discussed in greater
detail than for the primary and secondary treatment systems that
are in widespread use.
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Waste Reduction.
Techniques
CO
ro
Waste Reduction^
Effect
Point of
Application
Screening,
Skimming,
Settling -
Primary
Treat.
BOD, Sus
Solids,
Grease
Removal
to 98.5%
BOD
Figure 11. Suggested Meat Processor Waste Reduction Program
-------
IN-PLANT CONTROL TECHNIQUES
The waste load from a meat processing plant is composed of a
waste water stream containing the various pollutants described in
Section VI. The cost and effectiveness of treatment of the waste
stream will vary with the quantity of water and the waste load.
In fact, as indicated in Section V, the pollutant waste load
increases as water use increases. In-plant control techniques
will reduce both water use and waste Ipad. The latter will be
reduced directly by minimizing the entry of solids into the waste
water stream and indirectly by reducing water use.
The in-plant control techniques described below have been used in
meat processing plants and packing plants or have been
demonstrated as technically feasible.
Pickling and Curing solutions
These solutions are high in salt content and frequently high in
sugar content. Salt is a difficult pollutant to remove and sugar
has a very high BOD5. The operations involving injection or
soaking of meat products in these solutions should be equipped to
collect all of the solution presently wasted. The collection
pans and equipment should be designed to permit reuse of these
solutions. to, 11
Water Conservation Practices
The following practices and equipment should be used to reduce
the water consumption in plants and to achieve a reduction of the
pollutant waste load:10,11
1. Replace all drilled spray pipe systems with spray nozzles
designed and located to provide the specifically desired
water spray pattern.
2. Replace all washwater valves with squeeze- or press-to-open
valves wherever possible. Foot- and knee-operated valve
control is useful where operator fatigue is a problem or
where the operation requires the operator to work with
both hands.
3, Install foot-pedal operated handwashing and drinking
fountain water valves to eliminate continuously running
water.
4. Install spray-on-demand controls for sprayers which need
to operate only about 50 percent of the time or less.
5. Product chillers using cold water may be economically
replaced by chillers using a cryogenic liquid such as
nitrogen, thus reducing water consumption and perhaps
improving product quality.
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Waste water from the boiler (blowdown) is soft water and
should be considered for use in cleanup or in the plant
laundry. Detergent use will be reduced as well as water
conserved.
Plant cleanup as an operating procedure consumes a
substantial quantity of water in most plants. Reduced
water use can be achieved with equipment such as high
pressure spray systems, steam and water mix spray
systems, or automated clean-in-place (CIP) systems.
Management control is particularly vital in cleanup
operations if water is to be conserved and cleanliness
standards are to be maintained.
Whenever possible, water should be recycled or reused
in lower quality needs. The general rule should be to use
the lowest quality of water satisfactory for the
process.
Cleanup Operations
In addition to water conservation practices, other steps can also
be taken to reduce the waste load from cleanup. Floors and other
surfaces should be dry squeegeed or scraped prior to washdown,
wherever possible, to keep the maximum amount of solids and
grease out of the waste water. The drain baskets should be
pulled only after cleanup has been completed. Use a minimum of
water and detergent, consistent with cleaning requirements.
Automate cleaning of conveyors, piping and other equipment
wherever possible.*°,n
IN-PLANT PRIMARY TREATMENT
Flow Equalization
Equalization facilities consist of a holding tank and pumping
equipment designed to reduce the fluctuations of waste streams.
They can be economically advantageous, whether the industry is
treating its own wastes or discharging into a city sewer after
some pretreatment. The equalizing tank will store waste water
either for recycle or reuse, or to feed the flow uniformly to
treatment facilities throughout a 24-hour day. The tank is
characterized by a varying flow into the tank and a constant flow
out.
The major advantages of equalization are that treatment systems
can be smaller since they can be designed for the 24-hour average
rather than the peak flows, and secondary waste treatment systems
operate much better when not subjected to shock loads or
variations in feed rate.
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Screens
Since so much of the pollutant matter in meat wastes is
originally a solid (meat and fat particles), interception of the
waste material by various types of screens is a natural first
step. To assure the best performance on a plant waste water
stream, flow equalization should precede screening equipment.
Unfortunately, when the pollutant materials enter the sewage
stream, they are subjected to turbulence, pumping, and mechanical
screening and they break down and release soluble BOD into the
stream, along with colloidal, suspended, and greasy solids.
Waste treatment (that is, the removal of these solids after
discharge) is very expensive. It usually is far simpler and less
expensive to keep the solids out of the sewer entirely.
Static, vibrating and rotary screens are the primary types used
for this step in the in-plant primary treatment. Whenever
possible, pilot scale studies are warranted before selecting a
screen, unless specific operating data are available for the
specific use intended and under the same operating conditions.
Static Screens
The primary function of a static screen is to remove "free" or
transporting fluids. This can be accomplished in several ways,
and in most older concepts, only gravity drainage is involved. A
concavely curved screen design using high velocity pressure
feeding was developed and patented in the 1950's for mineral
classification and has been adapted to other uses in the process
industries. This design employs bar interference to the slurry
which knives off thin layers of the flow over the curved surface.
Beginning in 1969, United States and foreign patents were allowed
on a three-slope static screen made of specially coined curved
wires. This concept used the Coanda or wall attachment
phenomenon to withdraw the fluid from the under layer of a slurry
which is stratified by controlled velocity over the screen. This
method of operation has been found to be highly effective in
handling slurries containing fatty or sticky fibrous suspended
matter.
The specific arrangement and design of transverse wires provide a
relatively nonclogging surface for dewatering or screening. The
screens are precision-made in No. 316 stainless steel and are
extremely rugged.
Harder, wear-resisting stainless alloys may also be used for
special purposes. Openings of 0.025 to 0.15 cm (0.010 to 0.060
inch) meet normal screening needs.
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Vibrating Screens
The effectiveness of a vibrating screen depends on a rapid
motion. Vibrating screens operate between 900 rpm and 1800 rpm;
the motion can be either circular or straight line, varying from
0.08 to 1.27 cm (1/32 to 1/2 inch) total travel. The speed and
motion are selected by the screen manufacturer for the particular
application.
Of prime importance in the selection of a proper vibrating screen
is the application of the proper cloth. The capacities on liquid
vibrating screens are based on the percent of open area of the
cloth. The cloth is selected with the proper combination of
strength of wire and percent of open area. If the waste solids
to be handled are heavy and abrasive, wire of a greater thickness
and diameter should be used to assure long life. However, if the
material is light or sticky in nature, the durability of the
screening surface may be the least consideration. In such a
case, a light wire may be desired to provide an increased percent
of open area.
Rotary Screens
One type of barrel or rotary screen, driven by external rollers,
receives the waste water at one open end and discharges the
solids at the other open end. The screen is inclined toward the
exit end to facilitate movement of solids. The liquid passes
outward through the screen (usually stainless steel screen cloth
or perforated metal) to a receiver and then to the sewer. To
prevent clogging, the screen is usually sprayed continuously by a
line of external spray nozzles.1*
Another rotary screen commonly used throughout the meat industry
is driven by an external pinion gear. The raw waste water is fed
into the interior of the screen, below the longitudinal axis, and
solids are removed in a trough and screw conveyor mounted
lengthwise at the axis (center line) of the barrel. The liquid
exits outward through the screen into a tank under the screen.
The screen is partially submerged in the liquid in the tank. The
screen is usually 40 x 40 meshr with 0.4 mm (1/64 inch) openings.
Perforated lift paddles mounted lengthwise on the inside surface
of the screen assist in lifting the solids to the conveyor
trough. This type is also generally sprayed externally to reduce
blinding. Grease clogging can be reduced by coating the wire
cloth with teflon. Solids removal up to 82 percent is
reported.14
Applications
A broad range of applications exists for screens as the first
stage of in-plant waste water treatment. These include both the
plant waste water and waste water discharged from individual
processes, especially streams with high solids content.
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Catch Basins
The catch basin for the separation of grease and solids from meat
plant waste waters was originally developed to recover marketable
grease. Since the primary objective was grease recovery, all
improvements were centered on skimming. Many catch basins were
not equipped with automatic bottom sludge removal equipment.
These basins could often be completely drained to the sewer and
were "sludged out" weekly or at frequencies such that septic
conditions would not cause the sludge to rise. Rising sludge was
undesirable because it could affect the color and reduce the
market value of the grease.
In the past twenty years, with waste treatment gradually becoming
an added economic incentive, catch basin design has been improved
in the solids removal area as well. In fact, the low market
value of inedible grease and tallow has reduced concern about
quality of the skimmings, and now the concern is shifting toward
overall effluent quality improvement. Gravity grease recovery
systems will remove 20 to 30 percent of the BOD5, UO to 50
percent of the suspended solids, and 50 to 60 percent of the
grease (hexane solubles).
The majority of the gravity grease recovery basins (catch basins)
are rectangular. Flow rate is the most important criterion for
design; 30 to 40 minutes detention time at one-hour peak flow is
a common design sizing factor.11 The use of an equalizing tank
ahead of the catch basin obviously minimizes the size requirement
for the basin. A shallow basin—up to 1.8 m (6 feet)—is
preferred.
A "skimmer" skims the grease and scum off the top into collecting
troughs. A scraper moves the sludge at the bottom into a
submerged hopper from which it can be pumped. Both skimmings and
sludge go to by-product recovery.
Usually two identical catch basins, with a common wall, are
desirable so operation can continue if one is down for
maintenance or repair. Both concrete and steel tanks are used.
Concrete tanks have the inherent advantages of lower overall
maintenance and more permanence of structure. However, some
plants prefer to be able to modify their operation for future
expansion or alterations or even relocation.
Tanks fabricated entirely from steel have the advantage of being
semiportable, more easily field-erected, and more easily modified
than concrete tanks. The steel tanks, however, require
additional maintenance as a result of wear from abrasion and
corrosion.
A tank using steel walls and a concrete bottom is
best compromise between the completely steel
completely concrete tank. The advantages are the
probably the
tank and the
same as for
87
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steel; however, the steel tank requires a footing underneath the
supporting members, whereas the concrete bottom forms the floor
and supporting footings for the steel wall tank.
Dissolved Air Flotation
This system is, by definition, a primary treatment system; thus,
the effluent from a dissolved air flotation system is considered
raw waste. This system is normally used to remove fine suspended
solids and is particularly effective on grease in the waste
waters from meat processing and packing plants. It is a
relatively recent technology in the meat industry; however, it is
in fairly widespread use and increasing numbers of plants are
installing these systems, particularly in meat packing plants.
Dissolved air flotation appears to be the single most effective
device that a plant can use to reduce the pollutant waste load in
its raw waste water stream. It is expected that the use of
dissolved air flotation will become much more common in the
industry, especially as a step in achieving the 1983 standards.
Technical Description
Air flotation systems are used to remove any suspended material
from waste water with a specific gravity close to that of water.
The dissolved air system generates a supersaturated solution of
waste water and air by pressurizing the waste water stream and
introducing compressed air, then mixing the two in a detention
tank. This "supersaturated" waste water flows to a large
flotation tank where the pressure is released, thereby generating
numerous small air bubbles which effect the flotation of the
suspended organic material by one of three mechanisms: (1)
adhesion of the air bubbles to the particles of matter; (2)
trapping of the air bubbles in the floe structures of suspended
material as the bubbles rise; (3) adsorption of the air bubbles
as the floe structure is formed from the suspended organic
matter.12 In most cases, bottom sludge removal facilities are
also provided.
There are three process alternatives that differ by the
proportion of the waste water stream that is pressurized and into
which the compressed air is mixed. In the total pressurization
process. Figure 12, the entire waste water stream is raised to
full pressure for compressed air injection.
In partial pressurization. Figure 13, only a part of the waste
water stream is raised to the pressure of the compressed air for
subsequent mixing. Alternative A of Figure 13 shows a sidestream
of influent entering the detention tank, thus reducing the
pumping required in the system shown in Figure 12. In the
recycle pressurization process. Alternative B of Figure 13,
treated effluent from the flotation tank is recycled and
pressurized for mixing with the compressed air and then, at the
88
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Compressed-
Air
Feed
CO
fRetention\ >,
I Tank J
Flotation
Tank
i > Treated
Effluent
^_^
Tota 1 Pressurization x
~
Float to
Disposal
f
Process
Sludge to
Disposal
Figure 12. Dissolved Air Flotation
-------
Compressed
Air
Recycle Pressurizotion
Process
(Alternative B)
(Retention U
1
Feed from j,
Primary 1 ^ >
Treatment 1
i ^(Retention | 1
V Tank J
\ Treated
Flotation
Tank
• ^ t-inuein
\
SIu
Di
vk
Float to
Disposal
f
dgeto
sposal
Compressed
Air
Partial Pressurization
Process
(Alternative A)
Figure 13. Process Alternatives for Dissolved Air Flotation
-------
point of pressure release, is mixed with the influent waste
water. Operating costs may vary slightly, but performance should
be essentially equal among the alternatives.
Improved performance of the air flotation system is achieved by
coagulation of the suspended matter prior to treatment. This is
done by pH adjustment or the addition of coagulant chemicals, or
both. Aluminum sulfate, iron sulfate, lime, and polyelectrolytes
are used as coagulants at varying concentrations up to 300 to 400
mg/1 in the raw waste. These chemicals are essentially totally
removed in the dissolved air unit, thereby adding little or no
load to the downstream waste treatment systems. Chemical
precipitation is also discussed later, particularly in regard to
phosphorus removal, under tertiary treatment; phosphorus can also
be removed at this primary (in-plant) treatment stage, A slow
paddle mix will improve coagulation. It has been suggested that
the proteinaceous matter in meat processing and packing plant
waste could be removed by reducing the pH of the waste water to
the isoelectric point of about 3.5.42 The proteinaceous material
would be coagulated at that point and readily removed as float
from the top of the dissolved air unit. This is not being done
commercially in the meat industry in the United States at the
present time.
Similarly, the Alwatec process has been developed by a company in
Oslo, Norway, using a lignosulfonic acid precipitation and
dissolved air flotation to recover a high protein product that is
valuable as a feed.13 Nearly instantaneous protein precipitation
and hence, nitrogen removal, is achieved when a high protein
containing effluent, such as that from a meat processing plant,
is acidified to a pH between 3 and 4 with a high molecular weight
sodium salt of lignosulfonic acid. EOD5 reduction is reported to
range from 60 to 95 percent. The effluent must be neutralized
before further treatment by the addition of milk of lime or some
other inexpensive alkali. This process is being evaluated on
meat packing waste in one plant in the United States at the
present time.1*
Dissolved air flotation equipment may be expected to achieve
sustained removals of up to 60-percent for suspended solids and
80 to 90 percent grease removal without the addition of
chemicals. With the addition of 300 to UOO mg/1 of inorganic
coagulants and a slow mix to coagulate the organic matter, 90
percent or more of the suspended solids and grease can be
removed.*5 Nitrogen reduction between 35 and 70 percent was
found in dissolved air units surveyed in the meat packing
industry.
The operation of several dissolved air units was observed during
the verification sampling program and plant visits of the meat
packing industry. One plant that was visited controlled the feed
rate and pH of the waste water and achieved 90 to 95 percent
removal of solids and grease. Other plants had relatively good
operating success, but some did not achieve the results that
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should have been attainable, perhaps due
procedures.
Problems and Reliability
to improper operating
The reliability of the dissolved air flotation process and of the
equipment seems to be well established, although it is relatively
new technology for the meat processing industry. As indicated
above, it appears that the use of the dissolved air system is not
fully exploited by some of the companies who have installed it
for waste water treatment. The potential reliability of the
dissolved air process can be realized by proper installation and
operation. The feed rate and process conditions must be
maintained at the proper levels at all times to assure this
reliability. This fact does not seem to be fully understood or
of sufficient concern to some companies, and thus full benefit is
frequently not achieved.
The sludge and float taken from the dissolved air system can be
disposed of with the sludges obtained from secondary waste
treatment systems. The addition of polyelectrolyte chemicals was
reported to create some problems for sludge dewatering; however,
this may have been the unique experience of one or two plants.
The mechanical equipment involved in the dissolved air flotation
system is fairly simple, requiring standard maintenance attention
for such things as pumps and mechanical drives.
WASTE WATER TREATMENT SYSTEMS
The secondary treatment methods commonly used for the treatment
of meat processing and meat packing wastes after in-plant primary
treatment (solids removal) are the following biological systems:
anaerobic processes, aerobic lagoons, variations of the activated
sludge process, and high-rate trickling filters. Several of
these systems are capable of providing 70 to 97 percent BOD5
reductions and 80 to 95 percent suspended solids reduction, while
combinations of these systems can achieve reductions greater than
99 percent in BOD5 and grease, and greater than 97 percent in
suspended solids, as observed primarily in the meat packing
industry. Based on operating data from a pilot-plant system, the
rotating biological contactor also shows potential as a secondary
treatment system.
The selection of a secondary biological system for treatment of
meat processing wastes depends upon a number of important system
characteristics. Some of these are waste water volume, waste
load concentration, equipment used, pollutant reduction
effectiveness required, reliability, consistency, and resulting
secondary pollution problems (e.g., sludge) disposal and odor
control). The characteristics and performance of each of the
above mentioned secondary treatment systems, and also for common
combinations of them, are described in Section VIII.
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Anaerobic Processes
Elevated temperatures (29° to 35°C, or 85° to 95°F) and high
concentrations of carbohydrates, fats, proteins, and nutrients in
some meat processing wastes make these wastes well suited to
anaerobic treatment. Anaerobic or facultative microorganisms,
which function in the absence of dissolved oxygen, break down the
organic wastes to intermediates such as organic acids and
alcohols. Methane bacteria then convert the intermediates
primarily to carbon dioxide and methane. Unfortunately, much of
the organic nitrogen present in the influent is converted to
ammonia nitrogen. Also, if sulfur compounds are present (such as
from highsulfate raw water—50 to 100 mg/1 sulfate), hydrogen
sulfide will be generated. Acid conditions are undesirable
because methane formation is suppressed and noxious odors
develop. Anaerobic processes are economical because they provide
high overall removal of BOD5 and suspended solids with no power
cost (other than pumping) and with low land requirements. The
two types of anaerobic processes commonly used are anaerobic
lagoons and anaerobic contact systems.
Anaerobic Lagoons
Anaerobic lagoons are widely used in the meat packing industry as
the first step in secondary treatment or as pretreatment prior to
discharge to a municipal system. Reductions of up to 97 percent
in BOD5 and up to 95 percent in suspended solids can be achieved
with the lagoons; 85 percent reduction is common. Occasionally
two anaerobic lagoons are used in parallel and sometimes in
series. These lagoons are relatively deep (3 to 5 meters, or
about 10 to 17 feet), low surface area systems with typical waste
loadings of 240 to 320 kg BOD5/1000 cubic meters (15 to 20 Ib
BOD5/1000 cubic feet) and detention times of five to ten days. A
thick scum layer of grease is frequently allowed to accumulate on
the surface of the lagoon to retard heat loss, to ensure
anaerobic conditions, and hopefully to retain obnoxious odors.
Low pH and wind can adversely affect the scum layer. Paunch
manure and straw may be added to this scum layer by meat packing
plants.
Plastic covers of nylon-reinforced Hypalon, polyvinyl chloride,
and styrofoam have been used on occasion in place of the scum
layer; in fact, some states require this. Properly installed
covers provide a convenient means for odor control and collection
of the by-product methane gas.
The waste water flow inlet should be located near, but not on,
the bottom of the lagoon. In some installations, sludge is
recycled to ensure adequate anaerobic seed for the influent. The
outlet from the lagoon should be located to prevent short
circuiting of the flow and carry-over of the scum layer.
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For best operation, the pH should fce between 7.0 and 8.5. At
lower pH, methane-forming bacteria will not survive and the acid
formers will take over to produce very noxious odors. At a high
pH (above 8.5), acid forming bacteria will be suppressed and
lower the lagoon efficiency.
Advantages-Disadvantages. Advantages of an anaerobic lagoon
system are initial low cost, ease of operation, and the ability
to handle large grease loads and shock waste laods, and yet
continue to provide a consistent quality effluent.16
Disadvantages of an anaerobic lagoon are the hydrogen sulfide
generated from sulfate-containing waters and the typically high
ammonia concentrations in the effluent of 100 mg/1 or more. If
acid conditions develop, several odor problems result.
Incidentally, if the gases evolved are contained, it is possible
to use iron filing to remove sulfides.
Applications. Anaerobic lagoons used as the first stage in
secondary treatment are usually followed by aerobic lagoons.
Placing a small, mechanically aerated lagoon between the
anaerobic and aerobic lagoons is becoming popular. A number of
plants are currently installing extended aeration units following
the anaerobic lagoons to obtain nitrification. Anaerobic lagoons
are not permitted in some states or areas where the ground water
is high or the soil conditions are adverse (e.g., too porous), or
because of odor problems.
Anaerobic Contact System
Anaerobic contact systems require far more equipment for
operation than do anaerobic lagoons, and consequently are not as
frequently used, especially in the meat packing industry. The
equipment, as illustrated in Figure 14, consists of equalization
tanks, digesters with mixing equipment, air or vacuum gas
stripping units, and sedimentation tanks (clarifiers)* Overall
reduction of 90 to 97 percent in BOD5 and suspended solids is
achievable.
Equalized waste water flow is introduced into a mixed digester
where anaerobic decomposition takes place at a temperature of 33°
to 35°C (90° to 95°F). BOD5 loading into the digester is between
2.4 and 3.2 kg/cubic meter (0.15 and 0.20 It/cubic foot) and the
detention time is between three and twelve hours. After gas
stripping, the digester effluent is clarified and sludge is
recycled at a rate of about onethird the raw waste influent rate.
Sludge is removed from the system at the rate of about 2 percent
of the raw waste volume.
Advantages-Disadvantages. Advantages of the anaerobic contact
system are high organic waste load reduction in a relatively
short time; production and collection of methane gas that can be
used to maintain a high temperature in the digester and also to
94
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Equalizing Tank
Plant
8 Effluent
Sludge Recycle
Heaters
Anaerobic
Digestors
Gas
Stripping
Units
Sedimentation
Tanks
Effluent
Figure 14. Anaerobic Contact Process
-------
provide auxiliary heat and power; good effluent stability to
grease and waste load shocks; and application in areas where
anaerobic lagoons cannot be used. Disadvantages of anaerobic
contactors are higher initial cost and maintenance costs and
potential odor emissions from the clarifiers.
Applications. Anaerobic contact systems are restricted to use as
the first stage of secondary treatment and can be followed by the
same systems as anaerobic lagoons or roughing trickling filters.
Aerated Lagoons
Aerated lagoons have been used successfully for many years in a
small number of installations treating meat packing wastes.
However, with the tightening of effluent limitations, and because
aerated lagoons can provide the additional treatment, the number
of installations is increasing.
Aerated lagoons use either fixed mechanical turbine-type
aerators, floating propeller-type aerators, or a diffused air
system for supplying oxygen to the waste water. The lagoons
usually are 2.4 to 4.6 meters (8 to 15 feet) deep, and have a
detention time of two to ten days. BOD5 reductions range from 40
to 60 percent, with little or no reduction in suspended solids.
Because of this, aerated lagoons approach conditions similar to
extended aeration (discussed below) without sludge recycle.
Advantages-Disadvantages
Advantages of this system are that it can rapidly add dissolved
oxygen (DO) to convert anaerobic effluent to an aerobic state;
provide additional BOD5 reduction; and it requires a relatively
small amount of land. Disasvantages include the power
requirements and the fact that the aerated lagoon, in itself,
usually does not reduce BOD5 and suspended solids adequately to
be used as the final stage in a high performance secondary
system.
Applications
Aerated lagoons are usually the first or second stages of
secondary treatment, and must be followed by aerobic (shallow)
lagoons to reduce suspended solids and to provide the required
final treatment.
Aerobic Lagoons
Aerobic lagoons (stabilization lagoons or oxidation ponds) are
large surface area, shallow lagoons, usually 1 to 2.3 meters (3
to 8 feet) deep, loaded at a BODji rate of 23 to 57 kg per hectare
96
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(20 f' 50 pounds per acre). Detention times vary from about one
month to six or seven months; thus, aerobic lagoons require large
areas of land.
Aerobic lagoons serve three main functions in waste reduction:
o Allow solids to settle out;
o Equalize and control flow;
o Permit stabilization of organic matter by aerobic and
facultative microorganisms and also by algae.
Actually, if the pond is quite deep, 1.8 to 2.4 meters (6 to 8
feet), the waste water near the bottom may be void of dissolved
oxygen and anaerobic organi sms may be pre sent. Therefore,
settled solids can be decomposed into inert and soluble organic
matter by aerobic, anaerobic, or facultative organisms, depending
upon the lagoon conditions. The soluble organic matter is also
decomposed by microorganisms. It is essential to maintain
aerobic conditions in at least the upper six to twelve inches in
shallow lagoons, since aerobic microorganisms cause the most
complete removal of organic matter. Wind action assists in
carrying the upper layer of liquid (aerated by air-water
interface and photosynthesis) down into the deeper portions. The
anaerobic decomposition generally occurring in the bottom
converts solids to liquid organics, which can become nutrients
for the aerobic organisms in the upper zone.
Algae growth is common in aerobic lagoons; this currently is a
drawback when aerobic lagoons are used for final treatment
because the algae appear as suspended solids and contribute BOD5.
Algae added to receiving waters are thus considered a pollutant.
Algae in the effluent may be reduced by drawing off the lagoon
effluent at least 30 cm (about 14 inches) below the surface,
where concentrations are usually lower. Algae in the lagoon,
however, play an important role in stabilization. They use CO2,
sulfates, nitrates, phosphates, water and sunlight to synthesize
their own organic cellular matter and give off oxygen. The
oxygen may then be used by other microorganisms for their
metabolic processes. However, when algae die they release their
organic matter in the lagoon, causing a secondary loading.
Ammonia disappears without the appearance of an equivalent amount
of nitrite and nitrate in aerobic lagoons. From this, and the
fact that aerobic lagoons tend to become anaerobic near the
bottom, it appears that some denitrification is occurring.
Ice and snow cover in winter reduces the overall effectiveness of
aerobic lagoons by reducing algae activity, preventing mixing,
and preventing reaeration by wind action and diffusion. This
cover, if present for an extended period, can result in anaerobic
conditions. When there is no ice and snow cover on large aerobic
lagoons, high winds can develop a strong wave action that can
damage dikes. Riprap, segmented lagoons, and finger dikes are
97
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used to prevent wave damage. Finger dikes, when arranged
appropriately, also prevent short circuiting of the waste water
through the lagoon. Rodent and weed control, and dike
maintenance are all essential for good operation of the lagoons.
Advantages-Disadvantages Advantages of aerobic lagoons are that
they reduce the suspended solids and colloidal matter, and
oxidize the organic matter of the influent to the lagoon; they
also permit flow control and waste water storage. Disadvantages
are reduced effectiveness during winter months that may require
no discharge, the large land requirements, the algae growth
problem leading to higher suspended solids, and odor problems for
a short time in spring, after the ice melts and before the lagoon
becomes aerobic again.
Applications
Aerobic lagoons usually are the last stage in secondary treatment
and frequently follow anaerobic or anaerobic-plus-aerated
lagoons. Large aerobic lagoons allow plants to store waste
waters for discharge during periods of high flow in the receiving
body of water or to store for irrigation purposes during the
summer. These lagoons are particularly popular in rural areas
where land is available and relatively inexpensive.
Activated Sludge
The conventional activated sludge process is schematically shown
in Figure 15. In this process recycled biologically active
sludge or floe is mixed in aerated tanks or basins with waste
water. The microorganisms in the floe adsorb organic matter from
the wastes and convert it by oxidation-enzyme systems to such
stable products as carbon dioxide, water, and sometimes nitrates
and sulfates. The time required for digestion depends on the
type of waste and its concentration, but the average time is six
hours. The floe, which is a mixture of microorganisms (protozoa
and filamentous types), food, and slime material, can assimilate
organic matter rapidly when properly activated; hence, the name
activated sludge.
From the aeration tank the sludge-waste water mixture,
nitrification has taken place, is discharged to a sedimentation
tank. Here the sludge settles out, producing a clear effluent,
low in BOD5, and a biologically active sludge. A portion of the
settled sludge, normally about 20 percent, is recycled to serve
as an inoculum and to maintain a high mixed liquor suspended
solids content. Excess sludge is removed (wasted) from the
system, usually to thickeners and anaerobic digestion, or to
chemical treatment and dewatering by filtration or
centrifugation.
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Raw
Waste
to
Primary
Sedimentation
Secondary
Sedimentation
Aeration Tank
[_Return Activated Sludge
Waste
Sludge
Waste I
Sludge^
Effluent
Figure 15. Activated Sludge Process
-------
This conventional activated sludge process can reduce BOD5 and
suspended solids up to 95 percent. However, it cannot readily
handle shock loads and widely varying flows common to meat
processing waste waters without upstream flow equalization.
Various modifications of the activated sludge process have been
developed, such as the tapered aeration, step aeration, contact
stabilization, and extended aeration. Of these, extended
aeration processes are most frequently being used for treatment
of meat processing and meat packing wastes.
Extended Aeration
The extended aeration process is similar to the conventional
activated sludge process, except that the mixture of activated
sludge and raw materials is maintained in the aeration chamber
for longer periods of time. The usual detention time in extended
aeration ranges from one to three days, rather than six hours as
in the conventional process. During this prolonged contact
between the sludge and raw waste, there is ample time for the
organic matter to be adsorbed by the sludge and also for the
organisms to metabolize the organic matter which they have
adsorbed. This allows for a much greater removal of organic
matter. In addition, the organisms undergo a considerable amount
of endogenous respiration, and therefore oxidize much of the
organic matter which has been built up into the protoplasm of the
organism. Hence', in addition to high organic removals from the
waste waters, up to 75 percent of the organic matter of the
microorganisms are decomposed into stable products and
consequently less sludge will have to be handled.
In extended aeration, as in the conventional activated sludge
process, it is necessary to have a final sedimentation tank.
Some of the solids resulting from extended aeration are rather
finely divided and therefore settle slowly, requiring a longer
period of settling.
The long detention time in the extended aeration tank makes it
possible for nitrification to occur. In nitrification under
aerobic conditions, ammonia is converted to nitrites and nitrates
by specific groups of nitrifying bacteria. For this to occur, it
is necessary to have sludge detention times in excess of ten
days.*6 This can be accomplished by regulating the amounts of
recycled and wasted sludge. Oxygen-enriched gas could be used in
place of air in the aeration tanks to improve overall
performance. This would require that the aeration tank be
partitioned and covered, and that the air compressor and
dispersion system be replaced by a rotating sparger system. When
concurrent, staged flow and recirculation of gas back through the
liquor are employed, between 90 and 95 percent oxygen use is
claimed. Although this modification of extended aeration has not
been used in treating meat plant wastes, it is being used
successfully for treating other wastes.
100
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Advantages-Disadvantages., The advantages of the extended
aeration process are that it is immune to shock loading and flow
fluctuations because the incoming raw waste load is diluted by
the liquid in the system to a much greater extent than in the
conventional activated sludge. Also, because of the long
detention time, high BOD reductions can be obtained. Other
advantages of the system are the elimination of sludge digestion
equipment and the capability to produce a nitrified effluent.
Disadvantages are that it is difficult to remove most of the
suspended solids from the mixed liquor discharged from the
aeration tank; large volume tanks or basins are required to
accommodate the long detention times; and operating costs for
aeration are high.
Applications. Because of the nitrification process, extended
aeration systems are being used following anaerobic processes or
lagoons to produce low-BOD5 and low ammonia-nitrogen effluents.
They are also being used as the first stage of secondary
treatment, followed by polishing lagoons.
Trickling Filter
A trickling filter consists of a bed of rock or prefabricated
plastic filter media on the surface of which the microbial flora
develops; a rotary arm waste water distribution system; and an
under-drainage system. The distribution arm uniformly
distributes waste water over the filter media. The microflora
adsorbs and eventually metabolizes the organic matter in the
liquid as it trickles down through the media. When the growth
becomes fairly thick, it begins to slough off the surface of the
media as large pieces of solids, which are carried with the
liquid out through the under-drainage system. Consequently, the
trickling filter must be followed by an appropriate sedimentation
tank to remove the solids. To avoid clogging the trickling
filter, the waste water must be pretreated (primary, in-plant
treatment) to remove most solids and grease.
The high rate trickling filter is used in treating meat plant
waste waters either as a roughing filter, preceding conventional
secondary treatment such as activated sludge, or as complete
secondary, treatment in several stages. Hydraulic loading for
high rate trickling filters is generally in the range of 93.5 to
187 million liters per hectare (10 to 20 million gal. per acre)
per day.
Advantages~Disadvantaaes
Advantages of the roughing trickling filter are that it can
smooth out hydraulic and BOD_5 loadings and provide some initial
reduction in BOD5 (40 to 50 percent). Also, it is not materially
affected by extended inactivity, such as weekends. However, if
there are long periods of inactivity, it is desirable to
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recirculate the effluent of one of the settling tanks through the
filter to keep the floe moist. Another advantage of the roughing
filter is its reliability with minimum care and attention.
Disadvantages of the trickling filter system include high cost of
installation, the possible necessity to cover the filters in
winter to prevent freez ing, and effluent concentration
fluctuation with changes in incoming waste load.
Rotating Biological Contactor
Process Description
The rotating biological contactor (RBC) consists of a series of
closelyspaced flat parallel disks which are rotated while
partially immersed in the waste waters being treated. A
biological growth covering the surface of the disk adsorbs
dissolved organic matter present in the waste water. As the
biomass on the disk builds upf excess slime is sloughed off
periodically and is settled out in sedimentation tanks. The
rotation of the disk carries a thin film of waste water into the
air where it absorbs the oxygen necessary for the aerobic
biological activity of the biomass. The disk rotation also
promotes thorough mixing and contact between the biomass and the
waste waters. In many ways the RBC system is a compact version
of a trickling filter. In the trickling filter, the waste -waters
flow over the media and thus over the microbial flora; in the RBC
system, the flora is passed through the waste water.
The system can be staged to enhance overall waste load reduction.
Organisms on the disks selectively develop in each stage and are
thus particularly adapted to the composition of the waste in that
stage. The first stages might be used for removal of dissolved
organic matter, while the latter stages might be adapted to
nitrification of ammonia.
Development status
The RBC system was developed independently in Europe and the
United states about 1955 for the treatment of domestic waste; it
found application only in Europe, where there are an estimated
1000 domestic installations.16 However, the use of the RBC for
the treatment of meat plant waste is being evaluated at the
present time. The only operating information available on its
use on meat packing waste is from a pilot-scale system. The
pilot-plant studies were conducted with a four-stage RBC system
with four-foot diameter disks. The system was treating a portion
of the effluent from the Austin, Minnesota, anaerobic contact
plant used to treat meat packing waste. These results showed a
BOD5 removal in excess of 50 percent with loadings less than
0.037 kg BOD5 per unit area on an average BOD5 influent
concentration of approximately 25 mg/1.17
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Data from Autotrol Corporation, one of the suppliers of RBC
systems, revealed ammonia removal of greater than 90 percent by
nitrification in a multistage unit. Four to eight stages of
disks with maximum hydraulic loadings of 61 liters per day per
square meter (1.5 gallons per day per square foot) of disk area
are considered normal for ammonia removal.
A large installation was recently completed at the Iowa Beef
Processors plant in Dakota City, Nebraska, for the further
treatment of the effluent from an anaerobic lagoon.18 No data
are available on this installation, which has been plagued with
mechanical problems.
Advantages-Disadvantages
The major advantages of the RBC system are its relatively low
first cost; the ability to stage to obtain dissolved organic
matter reduction with the potential for removal of ammonia by
nitrification; and its good resistance to hydraulic shock loads.
Disadvantages are that the system should be housed, if located in
cold climates, to maintain high removal efficiencies and to
control odors. Although this system has demonstrated its
durability and reliability when used on domestic wastes in
Europe, it has not yet been fully proved on meat plant wastes.
Uses
Rotating biological contactors could be used for the entire
aerobic secondary system. The number of stages required depend
on the desired degree of treatment and the influent strength.
Typical applications of the rotating biological contactor,
however, may be for polishing the effluent from anaerobic
processes and from roughing trickling filters, and as
pretreatment prior to discharging wastes to a municipal system.
A BOD5 reduction of 98 percent is reportedly achievable with a
fourstage RBC.»*
Performance of Various Secondary Treatment Systems
Table 9 shows BOD5, suspended solids (SS), and grease removal
efficiencies for various biological treatment systems on meat
packing plant waste waters. Exemplary values each represent
results from an actual treatment system except for the data on
the anaerobic plus aerobic lagoon system which includes two
plants. The exemplary system is considered to be the most
effective for that type of treatment system and the selection is
based on data collected in on-site sampling.
The number of systems used to calculate average values are shown
in Table 9. It is apparent that the anaerobic plus aerobic
lagoon system is the most commonly used.
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Table 9. Performance of Various Secondary
Treatment Systems
Secondary Treatment System
(number of systems used
to determine averages)
Anaerobic + Aerobic
lagoon (22)
Anaerobic + aerated +
Aerobic lagoon (3)
Anaerobic Contact Process +
Aerobic lagoon (1)
Extended Aeration +
Aerobic lagoon (1)
Anaerobic lagoon + Rotating
Biological contactor
Anaerobic lagoon + Extended
Aeration 4- Aerobic lagoon
Anaerobic lagoon +
Trickling filter (1)
2-Stage Trickling filter (1)
Aerated + Aerobic
lagoon (1)
Anaerobic Contact (1)
Water Wasteload Reduction
Average Values
BOD 5
95.4
98.3
93.5
96.0
98. 5e
98e
97.5
95.5
99.4
96.9
SS
93.5
93.3
96.0
86.0
—
93e
94.0
95.0
94.5
97.1
Grease
95.3
98.5
99.0
98.0
98e
96.0
98.0
—
95.3
Exemplary Values
BOD 5
98.9
99.5
96.0
99.4
96.9
SS
96.6
97.5
86.0
94.5
97.1
Grease
98.9
99.2
98.0
—
95.8
e - estimated
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The estimated reduction of BOD5 shown for the anaerobic lagoon
plus rotating biological contractor is based on preliminary
pilot-plant results.
The values shown for the anaerobic lagoon plus extended aeration
system are based on estimates of their combined effectiveness
that are below the value calculated by using the average removal
efficiency for the two components of the system individually.
For example, if the BOD5 reduction for both the anaerobic lagoon
and the extended aeration were 90 percent, the calculated
efficiency of the two systems combined would be 99 percent.
TERTIARY AND ADVANCED TREATMENT
Chemical Precipitation of Phosphorus
Phosphorus is an excellent nutrient for algae and thus can
promote heavy algae blooms. As such, it cannot be discharged
into receiving streams and its concentration should not be
allowed to build up in a recycle water stream. However, the
presence of phosphorus is particularly useful in spray or flood
irrigation systems as a nutrient for plant growth.
The effectiveness of chemical precipitation. Figure 16, has been
verified in full scale during the North Star verification
sampling program of the meat packing industry. One packing plant
operates a dissolved air flotation system as a chemical
precipitation unit and achieves 95 percent phosphorus removal to
a concentration of less than 1 mg/1.
Float
Primary
or
PH
Ajustment
N
S
Chemical
Addition
s
>
/
V
Air
Flotation
Partial
Figure 16. Chemical Precipitation
Sludge
to
Disposal
Chemical precipitation can be used for primary (in-plant)
treatment to remove BOD5, suspended solids, and grease, as
discussed earlier in conjunction with dissolved air flotation.
Also, it can be used as a final treatment following biological
treatment to remove suspended solids in addition to phosphorus.
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Technical Description
Phosphorus occurs in waste water streams from meat plants
primarily as phosphate salts. Phosphates can be precipitated
with trivalent iron and trivalent aluminum salts. It can also be
rapidly precipitated by the addition of lime; however, the rate
of removal is controlled by the agglomeration of the precipitated
colloids and by the settling rate of the agglomerate.12
Laboratory investigation and experience with inplant operations
have substantially confirmed that phosphate removal is dependent
on pH and that this removal tends to be limited by the solubility
behavior of the three phosphate salts—calcium, aluminum, and
iron. The optimum pH for the iron and aluminum precipitation
occurs in the 4 to 6 range, whereas the calcium precipitation
occurs on the alkaline side at pH values above 9.5.*2
Since the removal of phosphorus is a two-step process involving
precipitation and then agglomeration, and both are sensitive to
pH, controlling the pH level takes on added significance. If a
chemical other than lime is used in the precipitation-coagulation
process, two levels of pH are required. Precipitation occurs on
the acid side and coagulation is best carried out on the alkaline
side. The precipitate is removed by sedimentation or by
dissolved air flotation.12 Polyelectrolytes are polymers that can
be used as primary coagulants, flocculation aids, filter aids, or
for sludge conditioning. Phosphorus removal may be enhanced by
the use of such polyelectrolytes by producing a better floe than
might occur without such chemical addition.19
The chemically precipitated sludge contains grease and organic
matter in addition to the phosphorus, if the system is used in
primary treatment. If it is used as a post-secondary treatment,
the sludge volume will be less and it will contain primarily
phosphorus salts. The sludge from either treatment can be
landfilled.
Development Status
This process is well established and understood technically.
Although its use on meat packing waste is very limited, it is
gaining acceptance as a primary waste treatment process. Where
it is in use, it is being operated successfully if the process
chemistry is understood and if the means to control the process
are available and properly used.
Problems and Reliability
As indicated above, the reliability of this process is well
established; however, it is a chemical process and as such
requires the appropriate control and operating procedures. The
problems that can be encountered in operating this process are
frequently the result of a lack of understanding or inadequate
equipment. Sludge disposal is not expected to be a problem.
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although the use of polyelectrolytes and their effect on the
dewatering properties of the sludge are open to some question at
the present time.
Sand Filter
A slow sand filter is a specially prepared bed of sand or other
mineral fines on which doses of waste water are intermittently
applied and from which effluent is removed by an under-drainage
system (Figure 17); it removes solids from the waste water
stream. BOD5 removal occurs primarily as a function of the
degree of solids removal, although some biological action occurs
in the top inch or two of sand. Effluent from the sand filter is
of a high quality, with BOD5 and suspended solids concentrations
of less than 10 mg/l.a° Although the performance of a sand
filter is well known and documented, it is not in common use
because it is not needed to reach current waste water standards.
A rapid sand filter may operate under pressure in a closed vessel
or may be built in open concrete tanks. It is primarily a water
treatment device and thus would be used as tertiary treatment,
following secondary treatment. Mixed media filters are special
versions of rapid sand filters that permit deeper bed penetration
by gradation of particle sizes in the bed. Up-flow filters are
also special cases of rapid filters.
Chtorination,
Optional
Primary or
Secondary
Treatment
Effluent
for Odor Control
v
'Treated
Effluent
Surface nr Back
Clean Wash
to Regenerate
Figure 17. Sand Filter System
Technical Description
The slow sand filter removes solids primarily at the surface of
the filter. The rapid sand filter is operated to allow a deeper
penetration of suspended solids into the sand bed and thereby
achieve solids removal through a greater cross section of the
bed. The rate of filtration of the rapid filter is up to 100
times that of the slow filter. Thus, the rapid filter requires
substantially less area than the slow filter; however, the cycle
time averages about 2U hours in comparison with cycles of up to
30 to 60 days for a slow filter.2* The larger area required for
the latter means a higher first cost. For small plants, the slow
sand filter can be used as secondary treatment. In larger sizes,
the labor in maintaining and cleaning the surface may mitigate
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its use. The rapid sand filter, on the other hand, can be used
following secondary treatment. However, it would tend to clog
quickly and require frequent backwashing, resulting in a high
water use, if used as secondary treatment. This wash water would
also need treatment if the rapid sand filter were used in
secondary treatment with only conventional solids removal
upstream in the plant.
The rapid filters operate essentially unattended with pressure
loss controls and piping installed for automatic backwashing.
They are contained in concrete structures or in steel tanks.19
Cleanup of the rapid sand filter requires backwashing of the bed
of sand with a greater quantity of water than used for the slow
sand filter. Backwashing is an effective cleanup procedure and
the only constraint is to minimize the washwater required in
cleanup, since this must be disposed of in some appropriate
manner other than discharging it to a stream.
Development Status
The slow sand filter has been in use for 50 years and more. It
has been particularly well suited to small cities and isolated
treatment systems serving hotels, motels, hospitals, etc., where
treatment of low flow is required and land and sand are
available. Treatment in these applications has been of sanitary-
or municipal-type raw waste. The Ohio Environmental Protection
Administration i's a strong advocate of slow sand filters as a
secondary treatment for small meat plants, following some form of
settling or solids removal. As of early 1973, 16 sand filters
had been installed and eight were proposed and expected to be
installed in Ohio. All 24 of these installations were on waste
from meat plants.zz The land requirements for a slow sand filter
are not particularly significant in relation to those required
for lagooning purposes in secondary treatment processes.
However, the quality and quantity of sand are important and may
be a constraint in the use of sand filters in some local
situations. It should also be recognized that this process
requires hand labor for raking the crust that develops on the
surface. Frequency of raking may be weekly or monthly, depending
upon the quality of pretreatment and the gradation of the sand.
Problems and Reliability
The reliability of the slow sand filter seems to be well
established in its long-term use as a municipal waste treatment
system. When the sand filter is operated intermittently there
should be little danger of operating mishap with resultant
discharge of untreated effluent or poor quality effluent. The
need for bed cleaning becomes evident with the reduction in
quality of the effluent or in the increased cycle time, both of
which are subject to monitoring and control. Operation in cold
climates is possible as long as the appropriate adjustment in the
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surface of the bed has been made to prevent blanking off the bed
by freezing water.
Chlorination, both before and after sand filtering, particularly
in the use of rapid filters, may be desirable to minimize or
eliminate potential odor problems and slimes that may cause
clogging.
The rapid sand filter has been used extensively in water
treatment plants and in municipal sewage treatment for tertiary
treatment; thus, its use in tertiary treatment of secondary
treated effluents from meat plants appears to be a practical
method of reducing BOD5 and suspended solids to levels below
those expected from conventional secondary treatment.
Microscreen-Microstrainer
A microstrainer is a filtering device that uses a fine mesh
screen on a partially submerged rotating drum to remove suspended
solids and thereby reduce the BOD5 associated with those solids.
Figure 18. The microstrainer is used as a tertiary treatment
following the removal of most of the solids from the waste water
stream, and suspended solids and BOD5 have been reduced to 3 to 5
mg/1 in applications on municipal waste,12 There are no reports
of their use in the tertiary treatment of meat plant wastes.
Secondary
Treatment
Effluent
Backwash to
Clear Screen/Strainer
Tertiary
Treated
Effluent
Figure 18. Microscreen/Microstrainer
Technical Description
The microstrainer is a filtration device in which a stainless
steel microfabric is used as the filtering medium. The steel
wire cloth is mounted on the periphery of a drum which is rotated
partially submerged in the waste water. Backwash immediately
follows the deposition of solids on the fabric, and in one
installation, this is followed by ultraviolet light exposure to
inhibit microbiological growth.12 The backwash water containing
the solids amounts to about 3 percent of the waste water stream
and must be disposed of by recycling to the secondary treatment
system.23 The drum is rotated at a minimum of 0.7, and up to a
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maximum of 4.3 revolutions per minute.12 The concentration and
percentage removal performance for microstainers on suspended
solids and BOD5 appear to be approximately the same as for sand
filters.
Development Status
While there is general information available on the performance
of microstrainers and on tests involving the use of them, there
appears to be only one recorded installation of a microstrainer
in use on municipal waste; the requirements for effluent quality
have not necessitated such installation. The economic
comparisons between sand filters and microstrainers are
inconclusive; the mechanical equipment required for the
microstrainer may be a greater factor than the land required for
the sand filter at the present time.
Problems and Reliability
The test performance of the microstrainer.fairly well establishes
the reliability of the device in its ability to remove suspended
solids and the associated BOD5. Operating and maintenance
problems have not been reported; this is probably because of the
limited use of the device in full-scale applications. As a
mechanical filtration device requiring a drive system, it would
have the normal maintenance requirements associated with
mechanical equipment. As a device based on microopenings in a
fabric, it would be particularly intolerant to any degree of
grease loading.
Nitrification-Denitrification
This two-step process of nitrification and denitrification.
Figure 19, is a system to remove the nitrogen which appears as
ammonia in treated meat plant waste waters, and it is of primary
importance for removal of the ammonia generated in anaerobic
secondary treatment systems. Ammonia removal is becoming more
important because of stream standards being set at levels as low
as 1 to 2 mg/1. Removal of ammonia can be virtually complete,
with nitrogen gas as the end product.
Technical Description
The large quantities of organic matter in raw waste from meat
processing and packing plants are frequently and effectively
treated in anaerobic lagoons. Much of the nitrogen in the
organic matter, present mainly as protein, is converted to
ammonia in anaerobic systems or in localized anaerobic
environments (see Figure 19). The sets of equations indicate
no
-------
Secondary
ireatment
Effluent
Aeration
System
^ Anaerobic ^ Aeration ^ Tertiary
/
* ' Pond ' Cell " Treated
Effluent
Carbon
Source,
e.g. Methanol
Figure 19. Nitrification/Denitrification
Nitrification:
NH3 + 02
NO-
(Nitrosomonas)
2N0
0
2HO.
(Nitrobacter)
Denitrification (using m'ethanol as carbon source)
6H4" + 6N03~ + 5CH3OH
5C02 + 3N2 + 13 H20
Small amounts of N20 and NO are also formed
(Facultative heterotrophs)
-------
the nitrification of the ammonia to nitrites and nitrates,
followed by the subsequent denitrification to nitrogen and
nitrous oxide.2* The responsible organisms are also indicated.
Nitrification does not occur to any great extent until most of
the carbonaceous material has been removed from the waste water
stream. The ammonia nitrification is carried out by aerating the
effluent sufficiently to assure the conversion of all the
nitrogen in the raw effluent to the nitrite-nitrate forms prior
to the anaerobic denitrification step.
The denitrification step, converting nitrates to nitrogen and
nitrogen oxides, takes place in the absence of oxygen. It is
thought to proceed too slowly without the addition of a
biodegradable carbon source such as sugar, ethyl alcohol, acetic
acid, or methanol. Methanol is the least expensive and performs
satisfactorily. Investigators working on this process have found
that a 30-percent excess of methanol over the stoichiometric
amount is required.i»,as
In current waste treatment practice using anaerobic and aerobic
lagoons, ammonia nitrogen that disappears in the aerobic system
does not show up to a large extent as nitrites and nitrates.
Ammonia stripping is not likely to account for the loss. It
appears that denitrification must actually be occurring in the
bottom reaches of the aerobic lagoons, where anaerobic conditions
are probably approached.
Presuming total conversion of the ammonia to nitrites or
nitrates, there will be virtually no nitrogen remaining in the
effluent from the denitrification process. Nitrogen removal can
be maintained at about 90 percent over the range of operating
temperatures; the rate increases with temperature to an optimum
value at approximately 30°C for most aerobic waste systems.
Temperature increases beyond 30° result in a decrease in the rate
for the mesophilic organisms.2*
The waste water is routed to a second aeration basin following
denitrification, where the nitrogen and nitrogen oxide are
readily stripped from the waste stream as gases. The sludge from
each stage is settled and recycled to preserve the organisms
required for each step in the process.
Development Status
The specific nitrification-denitrification process described
herein has only been carried out at the bench- and pilot-scale
levels. Gulp and Gulp* * suggest that the "practicality of
consistently maintaining the necessary biological reactions and
the related economics must be demonstrated on a plant-scale
before the potential of the process can be accurately evaluated."
A pilot model of a three-stage system using this process was
reportedly developed at the Cincinnati Water Research Laboratory
of the EPA and is being built at Manassas, Virginia.26 This work
112
-------
is also reported to be experimental. Thus, it can be concluded
that this process is, as of now, unproven. However, as mentioned
above, observations of treatment lagoons for meat packing plants
gives some indication that the suggested reactions are occurring
in present systems. Also, Halvorson27 reported that Pasveer is
achieving success in denitrification by carefully controlling the
reaction rate in an oxidation ditch, so that dissolved oxygen
levels drop to zero just before the water is reaerated by the
next rotor.
Problems and Reliability
In view of the experimental status of this process, it would be
premature to speculate on the reliability or problems incumbent
in a full-scale operation. It would appear that there would be
no exceptional maintenance or residual pollution problems
associated with this process in view of the mechanisms suggested
for its implementation at this time.
Ammonia Stripping
Ammonia stripping is a modification of the simple aeration
process for removing gases in water. Figure 20. Following pH
adjustment, the waste water is fed to a packed tower and allowed
to flow down through the tower with a countercurrent air stream
introduced at the bottom of the tower flowing upward to strip the
ammonia. Ammonia-nitrogen removals of up to 98 percent and down
to concentrations of less than 1 mg/1 have been achieved in
experimental ammonia stripping towers.19
Secondary
Treatment
Effluent
pH
Adjustment
Air
Blowers
Treated
Effluent
Figure 20. Ammonia Stripping
Technical Description
The pH of the waste water from a secondary treatment system is
adjusted to between 11 and 12 and the waste water is fed to a
packed or cooling tower type of stripping tower. As pH is
shifted to above 9, the ammonia is present as a soluble gas in
the waste water stream, rather than as the ammonium ion.25
Ammonia-nitrogen removal of 90 percent was achieved with
countercurrent air flows between 1.8 and 2.2 cubic meters per
113
-------
spray runoff irrigation is an alternative technique which has
been tested on the waste from a small meat packer and on cannery
waste.28 With this technique, about 50 percent of the waste
water applied to the soil is allowed to run off as a discharge
rather than no discharge, as discussed here. The runoff or
discharge from this type of irrigation system is of higher
quality than the waste water as applied, with BOD5 removal of
about 80 percent; total organic carbon and ammonia nitrogen are
about 85 percent reduced, and phosphorus is about 65 percent
reduced.2*,s'
Irrigation also provides a water supply for agricultural needs.
It is particularly useful in those same areas where the need for
water is greatest. Thus, there are a number of benefits from
irrigation of waste water: to the point source of the waste
water, to the farmer who makes use of the water, including the
contaminant nutrients, and to society because of the more
efficient use of resources.
The following factors will affect the ability of a particular
land area to absorb waste water: (1) character of the soil, (2)
stratification of the soil profile, (3) depth to groundwater, (4)
initial moisture content, and (5) terrain and groundcover.
The potentially greatest concern in the use of irrigation as a
disposal system is the total dissolved solids content and
particularly the salt content of the waste water. A maximum salt
content of 0.15 percent is suggested by Eckenfelder,z* Some
plants or some locations may require fresh water leaching as an
adjunct to waste water irrigation to minimize the impact of the
dissolved solids and the salt content to insure acceptable levels
for continuing application of the waste water on land.
An application rate of up to 330 liters per minute per hectare
(35 gallons per minute per acre) has been suggested in
determining the quantity of land required for various waste water
flows. This amounts to almost 5 cm (2 inches) of moisture per
day, and is relatively low in comparison with application rates
reported by Eckenfelder for various spray irrigation systems.2*
However, soils vary widely in their percolation properties and
experimental irrigation of a small area is recommended before a
complete system is built. In this report, land requirements were
based on 2.5 cm (one inch) applied per operating day for six
months of the year with lagoon storage for six-months' accumula-
tion of waste water.
Furthermore, it has been assumed that the area irrigated will be
managed to produce and harvest a forage crop. Thus, the economic
benefit from spray irrigation has been estimated on the basis of
raising two crops of grass or hay per season with a yield of 13.4
metric tons of dry matter per hectare (six tons per acre) and
valued at $22 per metric ton ($20 per ton). These figures are
reportedly conservative in terms of the number of crops and the
price to be expected from a grass or hay crop. The supply and
demand sensitivity as well as transportation problems for moving
116
-------
the crop to a consumer all militate against any more optimistic
estimate of economic benefits.30
Cold climate uses of spray irrigation may be subject to more
constraints and have greater land requirements than plants
operating in more temperate climates. However, a meat packer in
Illinois reportedly operated an irrigation system successfully.
Eckenfelder also reports that wastes have been successfully
disposed of by spray irrigation from a number of other
industries.24
North Star found in its survey of the meat industry that the
plants located in the arid regions of the southwest and
California were most inclined to use spray or flood irrigation
systems successfully. One plant was found that has been
irrigating cotton crops for more than 30 years with virtually
untreated waste water along with fresh water at about five times
the volume of the waste water.
Problems and Reliability
The long-term reliability of spray or flood irrigation systems is
a function of the ability of the soil to continue to accept the
waste, and thus reliability remains somewhat open to question.
Problems in maintenance are primarily in the control of the
dissolved solids level and salinity content of the waste water
stream and also in climatic limitations that may exist or
develop. Many soils may be improved by spray irrigation.
Ion Exchange
Ion exchange, as a tertiary waste treatment, is used as a
deionization process in which specific ionic species are removed
from the waste water stream. Figure 22. Ion exchange would be
used to remove salt (sodium chloride) from waters. Ion exchange
resin systems have been developed to remove specific ionic
species, to achieve maximum regeneration operating efficiency,
and to achieve a desired effluent quality. In treating meat
processing waste, the desired effluent quality would be a total
waste water salt concentration of 300 mg/1. Ion exchange systems
are available that will remove up to 90 percent of the salt in a
water stream.12 They can also be used to remove nitrogen.
Technical Description
The deionization of water by means of ion exchange resin involves
the use of both cation and anion exchange resins in sequence or
in combination to remove an electrolyte such as salt.
117
-------
The normal practice in deionization of water has been to make the
first pass through a strong acid column, cation exchange resin,
in which the first reaction shown in the equations occurs.
Effluent from the first column is passed to a second column of
anion exchange resin to remove the acid formed in the first step,
as indicated in the second reaction. As indicated in the two
reactions, the sodium chloride ions have been removed as ionic
species. A great variety of ion exchange resins have been
developed over the years for specific deionization objectives for
various water quality conditions.
Waste water treatment with ion exchange resins has been
investigated and attempted for over 40 years; however, recent
process developments in the treatment of secondary effluent have
been particularly successful in achieving high quality effluent
at reasonable capital and operating costs. One such process is a
modification of the Rohm and Hass, Desal process.12 In this
process a weak base ion exchange resin is converted to the
bicarbonate form and the secondary effluent is treated by the
resin to convert the inorganic salts. After the first step, the
process includes a floculation/aeration and precipitation step to
remove organic matter; however, this should be unnecessary if a
sand filter or comparable system is used upstream of the ion
exchange system. The effluent from the first ion exchange column
is further treated by a weak cation resin to reduce the final
dissolved salt content to approximately 5 mg/1. The anion resin
in this process is regenerated with aqueous ammonia, and the
cation resin with an aqueous sulfuric acid. The resins did not
appear to be susceptible to fouling by the organic constituents
of the secondary effluent used in this experiment.
Other types of resins are available for ammonia, nitrate, or
phosphate removal as well as for color bodies, COD and fine
suspended matter. Removal of these variuos constituents can
range from 75 percent to 97 percent, depending on the
constituent.*»
The cycle time on the ion exchange unit will be a function of the
time required to block or to take up the ion exchange sites
available in the resin contained in the system. Blockage occurs
when the resin is fouled by suspended matter and other
contaminants. The ion exchange system is ideally located at the
end of the waste water processing scheme, thus having the highest
quality effluent available as a feedwater.
To achieve a recycleable water quality, it may be assumed that
less than 500 mg/1 of total dissolved solids would have to be
achieved. Of the total dissolved solids, 300 ppm of salt are
assumed to be acceptable. To achieve this final effluent
quality, some portion or all of the waste water stream would be
subjected to ion exchange treatment.
The residual pollution will be that resulting from regeneration
of the ion exchange bed. The resin systems, as indicated
118
-------
Partial
Tertiary
Treatment
Effluent
Backwash ft
Regenerant
System
Tertiary
Treated
Effluent
Figure 22. Ion Exchange
-------
earlier, can be tailored to specific ion removal and efficient
use of regeneration chemicals, thus minimizing liquid wastes from
the regeneration step.
Development status
Ion exchange as a unit operation is well established and commonly
used in a wide range of applications in water treatment and water
deionization. Water softening for boiler feed treatment and
domestic and commercial use is probably the most widespread use
of ion exchange in water treatment. Deionization of water by ion
exchange is used to remove carbon dioxide; metal salts such as
chlorides, sulfates, nitrates, and phosphates; silica; and
alkalinity. Specific resin applications such as in waste water
treatment have not been widespread up to the present time, since
there has not been a need for such a level of treatment.
However, process development and experimental work have shown the
capability of ion exchange systems to achieve the water quality
that may be required particularly for closed-loop water recycle
systems.
Part of the economic success of an ion exchange system in
treating processing plant waste will probably depend on a high
quality effluent being available as a feed material. This again,
can be provided by an upstream treatment system such as sand
filtration to remove a maximum of the particularly bothersome
suspended organic material. However, the effect of a low quality
feed would be primarily economic because of shorter cycle times,
rather than a reduction in the overall effectiveness of the ion
exchange system in removing a specific ionic species such as
salt.
Problems and Reliability
Inasmuch as ion exchange is widely used, the reliability of the
concept is well established. The application of the technology
in meat processing waste treatment has not been tested and
therefore the reliability in that application has yet to be
established. The problems associated with ion exchange
operations would primarily center on the quality of the feed to
the ion exchange system and its effect on the cycle time. other
concerns, particularly for devising the scope of a given ion
exchange system, include means for disposal of spent regenerants
and brine concentrates which may require careful consideration to
avoid soil or ground water contamination. The operation and
control of the deionization-regeneration cycle can be totally
automated, which would seem to be the desired approach. Re-
generation solution is used periodically to restore the ion
exchange resin to its original state for continued use. This
solution must be disposed of following its use and that may
require special handling or treatment. The relatively small
quantity of regenerant solution will facilitate its proper
disposal by users of this system.
120
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SECTION VIII
COST, ENERGY, AND NONWATER QUALITY ASPECTS
SUMMARY
The waste water from meat processing plants is amenable to
treatment in secondary and tertiary waste treatment systems to
achieve low levels of pollutants in the final effluent, In-plant
controls, by-product recovery operations, and strict water
management practices can be highly effective in reducing the
waste load and waste water flow from any meat processing plant.
The water management practices will reduce the requisite size of
secondary and tertiary treatment systems and improve their waste
reduction effectiveness.
The additional investment required of a "typical" plant in each
subcategory to install a waste water treatment system to achieve
the indicated performance is presented in Table 10. A "typical"
plant is a hypothetical plant in each subcategory with a waste
water volume and raw waste BOD5 equal to the average for the
subcategory, as indicated on the following page.
Small Processor
Meat Cutter
Sausage and Luncheon
Meat Processor
Ham Processor
Meat Canner
Flow
3200 liters/day
(840 gal./day)
38,000 liters/day
(10,000 gal./day)
454,000 liters/day
(120,000 gal./day)
352,000 liters/day
(93,000 gal./day)
908,000 liters/day
(240,000 gal./day)
BOD5
1.06 kg/kkg FP
0.52 kg/kkg FP
2.65 kg/kkg FP
5.5 kg/kkg FP
11.5 kg/kkg FP
Typical plants in the industry, other than small processors, will
need to add chlorination treatment to their existing treatment
systems to meet the 1977 limitations or by management intent in
pursuit of recycleable effluents in plants. The 1983 limitations
may require the addition of some of the following treatment to
existing systems by the large processors:
Chemical precipitation to remove phosphates and suspended
solids
Ammonia stripping
Sand filter for solids removal
Chlorination
Denitrification for nitrate and nitrite removal.
121
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Table 10. Additional Investment Cost for the "Typical"
Plant in Each Subcategory to Achieve indicated
Standards
ro
no
1977
Subcategory Standards
Small Processor '0
Meat Cutters $2500
Sausage and 4500
Luncheon Meat
Processor
Ham Processor 4000
Meat Canner 6500
1983
Standards
0
$192,000
316,000
297,000
366,000
Irrigation
—
$ 6,400
55,000
46,000
101,000
New Point
Source
Standards
$ 5,000
60,000
130,000
115,000
190..000
-------
Table 11. Addition to the Total Annual Cost and Operating* Cost for a Plant
in Each Subcategory to Operate Treatment System as Described
Subcategory
Small Processor
Meat Cutter
Sausage and
Luncheon Meat
Processor
Ham Processor
Meat Canner
1977 Standards
Operating
Cost
0
$20,000
20,000
20,000
20,000
Annual
Cost
0
$20,000
20,000
20,000
20,000
1983 Standards
Operating
Cost
0
$32,600
40,000
39,100
43,900
Annual
Cost
0
$ 71,000
103,000
98,500
117,000
Irrigation
Operating
Cost
0
$ $3,800
600
1,300
(3,100)
Annual
Cost
0
$ 5,100
9,500
8,800
12,900
New Point Sources
Operating
Cost
$ 200
14,800
20,300
19,100
25,800
Annual
Cost
$ 1,200
26,600
44,500
41,100
61,400
ro
CO
*Total annual cost includes operating cost plus capital cost and depreciation in dollars per year.
Total operating cost includes manpower and burden, supplies, chemicals, power, taxes, and
insurance in dollars per year.
-------
The ammonia stripping and denitrification may not be necessary
fnr exvtxm r»is»rH-_ jf neither is needed, the
for every plant. If neither is needed, the tot
investment for a plant is reduced to about 55 percent
indicated in Table 10.
j
total capital
of that
The cost of the irrigation option is presented to demonstrate the
economic attraction of a waste treatment system that produces no
discharge. Irrigation by the small processor may be attractive
in specific situations, but does not seem to be necessary or
warranted for general use.
The investment costs for new point sources of waste water
effluent are cost estimates of treatment systems presently in use
in the industry, based on the average flow for the subcategory as
previously discussed. The estimated total investment cost for
the meat processing industry to achieve the 1977 limitations is
$2.5 million. Among the respondents to the questionnaire survey
of the industry, no plants were found to be dumping raw waste.
However, it was assumed that one-half of 1.0 percent of the
industry—20 plants—are dumping raw waste into receiving bodies
of water. These plants are estimated to require an investment
equal to the new point source cost indicated in Table 10. This
cost for the 20 plants plus the cost for adding chlorination to
the plants with treatment results in the estimated $2.5 million
cost for the industry.
The estimated total investment cost for the meat processing
industry to achieve the 1983 limitations varies between $33
million and $60 million, depending on the need for specific
treatment processes throughout the industry.
The investment cost required of the industry for the 1983
limitations involves only those plants that treat their own waste
water, or about 12 percent of the number of plants in the
industry. Based on the distribution of plants between the
subcategories as found in the study survey and the average
production for each subcategory, the investment cost per annual
kg FP is found to vary between 1.3 and 2.4 cents (0.6 to 1,1
cents per annual Ib FP) for those plants with waste water
treatment.
The additions to plant operating cost and total annual cost, in
total dollars and per unit of production, for the treatment
systems required to achieve the proposed limitations are listed
in Tables 11 and 12. The additional costs listed for 1977 are
the result of adding chlorination and the equivalent of 0.5 man-
years, including a burden rate of 50 percent. The negative
operating cost for the irrigation of the canned meats waste water
results from the revenue from the grass crops harvested on the
irrigated land. The additional annual unit costs vary from about
0.5 to 1.2 cents per kg of product (0.2 to 0.5 cents per Ib) to
meet the 1983 requirements. The unit operating cost addition for
the 1983 limitations, which does not include capital and
depreciation costs, amounts to about 40 percent of the total
124
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Table 12. Additions to the Annual Cost and Operating Cost Per Unit of Production for
a Plant in Each Subcategory to Operate Treatment System as Described
Subcategory
Small Processor
Meat Cutter
Sausage and
Luncheon Meat
Processor
Ham Processor
Meat Canner
C/kg
(C/lb)
C/kg
(C/lb)
C/kg
(C/lb)
C/kg
(C/lb)
C/kg
(C/lb)
1977 Standards
Operating
Cost
0
0.12
(0.06)
0.16
(0.08)
0.24
(0.12)
0.10
0.05
Annual
Cost
0
0.12
(0.06)
0.16
(0.08)
0.24
(0.12)
0.10
0,05
1983 Standards
Operating
Cost
0
0.20
(0.09)
0.34
(0.15)
0.47
(0.21)
0.22
(0.10)
Annual
Cost
0
0.45
(0.20)
0.86
(0.39)
1.19
(0.54)
0.58
(0.26)
Irrigation
Operating
Cost
0
0.02
(0.01)
0.005
(0.002)
0.02
(0.007)
0.02*
(0.007)*
Annual
Cost
0
0.03
(0.015)
0.08
(0.04)
0.11
(0.05)
0.06
(0.03)
New Point Source
Operating
Cost
0.08
(0.04)
0.09
(0.04)
0.17
(0.08)
0.23
(0.10)
0.13
(0.06)
Annual
Cost
0.05
0.02
0.17
(0.08)
0.37
(0.17)
0.50
(0.23)
0.30
(0.14)
r\>
en
*Profit
-------
annual unit cost increase for the plants with waste water
treatment in the large processor subcategories.
Neither the capital requirements nor the additions to the
operating and total annual costs appears to exceed the
capabilities of plants in the industry to raise the capital or to
compete effectively and profitably and to earn a satisfactory
return. An estimate of the ten-year total of capital
expenditures (1963 to 1972) for the meat processing industry is
$360 million. The small processor subcategory would account for
about 5.0 percent of that total, or about $18 million. Recent
expenditures by the large processor segment of the industry are
estimated to be in the middle $40-million-per-year range.
The total energy consumption in waste water treatment by the meat
processing industry is of essentially no consequence in
comparison to the present power consumption. The waste treatment
power consumption amounts to about 1.4 percent of the current
total consumption of fuel and electricity by meat processors.
With the implementation of the proposed standards, land becomes
the primary waste sink instead of air and water. The waste to be
land filled can improve soils with nutrients and soil
conditioners contained in the waste. Odor problems can be
avoided or eliminated in all treatment systems.
"TYPICAL" PLANT
The waste treatment systems applicable to waste water from the
meat processing industry can be used by plants in the large
processors subcategories of the industry. A hypothetical
"typical" plant was constructed in each subcategory as the basis
for estimating investment cost and total annual cost for the
application of each waste treatment system within each
subcategory. The costs were estimated and, in addition, effluent
reduction, energy requirements, and nonwater quality aspects of
the treatment systems were determined.
The waste treatment systems are applied on the basis of the plant
constructs for each subcategory, as shown in Table 13.
126
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WASTE TREATMENT SYSTEMS
The waste treatment systems included in this report as
appropriate for use on meat processing plant waste water streams
can be used, subject to specific operating constraints or
limitations as described later, by most plants in the industry.
The use of some treatment systems may be precluded from
consideration by technical, physical, or economic impracticality
for some plants.
The waste treatment systems, their uses, and the minimum effluent
reduction associated with each are listed in Table 14.
The dissolved air flotation system can be used upstream of any
secondary treatment system. When operated without chemicals, the
by-product grease recovered from the skimmings has a market value
estimated at 110/kg (52/lb). The use of chemicals will increase
the quantity of grease removed from the waste water stream, but
may reduce the value of the grease because of the chemical
contaminants.
The secondary treatment systems are generally land intensive
because of the long retention time required in natural biological
processes. Mechanically assisted systems have reduced the land
requirements, but increased the energy consumption and cost of
equipment to achieve comparable levels of waste reduction, some
of the tertiary systems are interchangeable. They can be used at
the end of any of the secondary treatment systems, as required to
achieve a specific effluent quality. Chlorination is included as
a disinfection treatment. A final clarifer has been included in
costing out all biological treatment systems that generate a
substantial sludge volume; e.g., extended aeration and activated
sludge. The clarifer is needed to reduce the solids content of
the final effluent.
The most feasible system for large processors to achieve no
discharge at this time is flood or spray irrigation or, in some
cases, evaporation from a shallow pond. Closing the loop to a
total water recycle or reuse system is technically feasible,
particularly as a potential method for reducing fresh water needs
in many clean-up operations. The irrigation option does require
large plots of accessible land—roughly 2.0 hectares/million
liters (1.8 acres/thousand gallons) of waste water per day and
limited concentrations of dissolved solids. More detailed
descriptions of each treatment system and its effectiveness are
presented in Section VII—Control and Treatment Technology.
Of all the plants responding to the study questionnaire, ten
percent reported having their own waste water treatment, 90
percent indicated discharging raw waste to a municipal treatment
system. Fifteen plants reported some on-site secondary
treatment. Ten of the fifteen are small processors using septic
127
-------
tank systems. The others use a variety of combinations of
secondary treatment processes.
Dissolved air flotation is used as primary treatment along with a
catch basin by two plants in the sample. Chlorination is used by
five plants, according to the available information.
Other than sand filters and irrigation, there is no reported use
of any of the advanced treatment systems. Sand filters are
preferred for secondary treatment in Ohio instead of anaerobic
lagoons, which are discouraged by the Ohio Environmental
Protection Administration. Irrigation systems tend to be located
in arid regions of the Southwest and California.
Municipal treatment is used by most of the industry. The small
processors not connected to city sewers have achieved a "no
discharge" treatment level with septic tank systems. A breakdown
of the sample by subcategory is indicated in Table 15.
Table 13. Operating Parameters for "Typical" Plants
Plant
Parameter
Production
kkg/day
(1000 Ib/day)
Total waste
water flow
liters /day
(gal. /day)
Waste water flow
liter s/kkg FP
Cgal./lOOO lb FP)
Raw waste, BOD5
kg/kkg FP
(lb/1000 lb FP)
Industry Subcategory
Small
Processor
0.95
(2.10)
3200
(840)
3335
(400)
1.06
(1.06)
Meat
Cutter
63
(138)
38,000
(10,000)
600
(72)
0.52
(0.52)
S aus age
& Luncheon
Meat
Processor
48
(105)
454,000
(120,000)
9,600
(1,150)
2.65
(2.65)
Ham
Processor
33
(73)
352,000
(93,000)
10,600
(1,270)
5.5
(5.5)
Meat
Canner
81
(178)
908,000
(204,000)
11,250
(1,350)
11.5
(IKS)
TREATMENT AND CONTROL COSTS
In-Plant Control Costs
The cost of installation of in-plant controls is primarily a
function of the specific plant situation. Building layout and
construction design will largely dictate what can be done, how.
128
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Table 14. Waste Treatment Systems, Use and Effectiveness
Treatment
System
Use
Effluent Reduction
Dissolved air flotation
(DAF)
DAF with pH control and
flocculants added
Anaerobic + aerobic
lagoons
Anaerobic + aerated +
aerobic lagoons
Anaerobic contact
process
Activated sludge
Extended aeration
Anaerobic lagoons +
rotating biological
contactor
Chlorination
Sand filter,
Microstrainer
Electrodialysis
Ion exchange
Ammonia stripping
Carbon adsorption
Chemical precipitation
Reverse osmosis
Spray irrigation
Flood irrigation
Ponding and evaporation
Primary treatment
or by-product
recovery
Primary treatment
or by-product
recovery
Secondary treatment
Secondary treatment
Secondary treatment
Secondary treatment
Secondary treatment
Secondary treatment
Finish and
disinfection
Tertiary treatment &
Secondary treatment
Tertiary treatment
Tertiary treatment
Tertiary treatment
Tertiary treatment
Tertiary treatment
Tertiary treatment
Tertiary treatment
No discharge
No discharge
No discharge
Grease, 60% removal, to
100 to 200 mg/1
BOD5, 30% removal
SS, 30% removal
Grease, 95-99% removal,
BOD5, 90% removal
SS, 98% removal
BOD , 95% removal
BOD , to 99% removal
BOD , 90-95% removal
BOD , 90-95% removal
BOD , 95% removal
BOD , 90-95% removal
BOD5, to 5-10 mg/1
SS, to 3-8 mg/1
BOD5, to 10-20 mg/1
SS, to 10-15 mg/1
TDS, 90% removal
Salt, 90% removal
90-95% removal
BOD5, to 98% removal as
colloidal & dissolved
organic
Phosphorus, 85-95% removal,
to 0.5 mg/1 or less
Salt, to 5 mg/1
TDS, to 20 mg/1
Total
Total
Total
129
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Table 15. Secondary Treatment by Each Subcategory (%)
CO
o
Municipal
treatment
Secondary
treatment
No discharge
TOTAL
Small
Processor
88
0
12
100%
Meat
Cutter
83
17
0
100%
Sausage &
Luncheon
Meat
Processor
90*
(eat.)
10
(eat.)
0
100%
Ham
Processor .
88
8
4
100%
Meat
Canner
89
11
0
100%
North Star
Sample of
Total
Industry
90.4
2.7
6.9
100%
*The 90-10 split for the sausage and luncheon meats subcategory is an
estimate which differs from the sample results, but is based on the
practices in the other large processor eubcategories.
-------
and at what cost in regard to in-plant waste control techniques.
Therefore, no in-plant control costs were included in the
investment cost estimates. Rough approximations of the range of
costs for the in-plant controls requiring capital equipment are
listed in Table 16.
Table 16. In-Flant Control Equipment Cost Estimates
Plant Area
Item
Equipment Cost Range
Pickle and Curing
Solutions
Water Conservation
Water Conservation
Solution collection,
treatment, reuse
system
Install spray
nozzles
Press-to-open and
foot operated valves
$10,000 - $20,000
$3,000 - $6,000
$5,000 - $10,000
Investment Costs Assumptions
The waste treatment system costs are based on plant production,
waste water flow, and BOD5 figures listed previously for a
"typical," but hypothetical, plant in each subcategory„
Investment costs for specific waste treatment systems are largely
dependent on the waste water flow. Some of the lagoon systems
are designed on BOD5 loading, which has been shown to increase
with increased water use.
Cost effectiveness data is presented in Figures 23, 24, and 25,
as investment cost required to achieve the indicated BOD5 removal
with two different waste treatment systems (shown in the text
below as "low cost" and "high cost" systems) at three levels of
131
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waste water flow. The lowest flow (Figure 23) is the average for
the meat cutters subcategory; the highest flow (Figure 25) is the
canners average, and the intermediate flow (Figure 24) is within
20 percent of the average flow for each of the other two large
processor subcategories. The raw waste reduction is based on the
construct of waste treatment systems with-the incremental waste
reduction achieved by adding treatment components to the system
as indicated in the table below.
Both the low- and high-cost systems include treatment components
and combinations that are in use in the meat processing and meat
packing industry. The raw waste reduction is based on the data
reported in Section VII and this section.
Low Cost System
Total Raw
Waste Reduction
High Cost System
Catch basin
* Dissolved air
flotation
* Anaerobic" and
aerobic lagoons
+ Aerated lagoon
+ Sand filter
Catch basin
+ Dissolved air
flotation
+ Activated sludge
+ Extended aeration
+ Sand filter
0
30
95
98
99 +
In averaging the wa ste water flow for the 1 arge processor
subcategories, it was found that one standard deviation was about
100 percent of the average total water flow. This variability
coupled with that in the cost estimating suggests that the waste
treatment investment costs for a specific plant may be only
within an accuracy of * 50 to 100 percent.
The investment cost data were collected from the literature,
personal plant visits, equipment manufacturers, engineering
contractors, and consultants. The costs are "ball-park" type
estimates implying an accuracy of _+ 20 to 25 percent. Rarely is
it minus. All costs are reported in August 1971 dollars,
Percentage factors were added to the basic treatment system cost
estimate for design and engineering (10 percent) and for
contingencies and omissions (15 percent) . Land costs were
estimated to be $2470 per hectare ($1000 per acre) .
In addition to the variation in plant water flows and
loadings, and the inherent inaccuracy in cost estimating, one
additional factor further limits the probability of obtaining
132
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OJ
GO
99.9
H 99.5
Z
B "
UJ 98
a.
o ^
i—
8 90
Q
UJ
a:
80
o
§ 70
UJ 60
< 50
>
40
< 30
a: 'yj
[if 20
5
g 10
a:
Q- /-
Q. ^
^
-
LAGOON
TREATMENT -7
/ i
SYSTEM /
Z_»j j
1
1
1
1
1
1
1
1
1
1
|
1
1
• I
|
1
1!
. I i * ^FrnMHAPY TnrflTMriMT
^" — w oc.'wL/wuHrt T i nc.Mi mciM i
ACTIVATED
SLUDGE a
— EXTENDED
AERATION
SYSTEM
KKIMMrXT IKC.MIIVIC.rMI
•
•
itiiliiliillllili
0 40 80 120 160 200 240 280 320 360 400 440 480 520 560 600 640 680 720
INVESTMENT COST ($IOOO's)
Figure 23. Waste Treatment Cost Effectiveness at Flow
of 38,000 Liters/Day (10,000 GPD)
-------
CO
APPROXIMATE RAW WASTE LOAD REDUCTION (PERCENT)
o o 8 8 § § 8 3 8 88 $8?
-h u
A
S
E
A
S
?
CTIVATED
LUDGE a
XTENDED
ERATION
YSTEM
i i
40 80 120
-
•
1
1
1
1
• StOONUARY TREATMENT
LAGOON
.- TRFATMFNT
SYSTEM
rmiviMru inc.Miiwc.iMi
i i i i i i i i i i i i i i i
160 200 240 280 320 360 400 440 480 520 560 600 640 680 720
INVESTMENT COST ( $ 1000's)
Figure 24. Waste Treatment Cost Effectiveness at Flow
of 380,000 Liters/Bay (100,000 GPD)
-------
99.9 •
CO
Ul
URGENT
CD
0 to
-------
precise cost estimates for waste treatment systems. This factor
was reported by a number of informed sources who indicated that
municipal treatment systems will cost up to 50 percent more than
comparable industrial installations. The literature usually
makes no distinction between municipal or industrial installation
in reporting investment costs.
Annual Costs Assumptions
The components of total annual cost are capital cost,
depreciation, operating and maintenance costs, and energy and
power costs. The cost of capital is estimated to be ten percent
of the investment cost for the meat processing industry, or the
same as the meat packing industry. This cost should be a
weighted average of the cost of equity and of debt financing
throughout the industry. Neither individual companies nor
industry associations have a known figure for this cost.
Presuming that target and realized return-on-investment (ROI) or
return-on-assets (ROA) figures incorporate some estimate of
capital cost plus an acceptable profit or return, industry and
corporate reports were used as a guide in selecting the ten
percent figure for the meat packing industry. One sample of
companies reported earning 7.1 percent of total assets for
1971.3* A recent business periodical reported earnings at 10.1
percent of invested capital,32 and general industry sources
report corporate target ROI and ROA figures at 12 to 15 percent
for new ventures. The ten percent figure is probably
conservative and thus tends to contribute to a high estimate of
total annual cost. Operating cost includes all the components of
total annual cost except capital cost and depreciation, wherever
it is reported.
The depreciation component of annual cost was estimated on a
straightline basis over the following lifetimes, with no salvage
value:
Land costs — not depreciated
All other investment costs for treatment—10 years
The operating and maintenance costs for the 1983 system include
the cost of one man-year at $4.20 per hour plus 50 percent for
burden, supervision, etc. A licensed waste treatment operator
would add another $5000 to operating costs per year. One-half
man-year was used for the annual cost for the 1977 limitations
plus the 50 percent burden, etc. General and maintenance
supplies, taxes, insurance, and miscellaneous operating costs
were estimated as 5.0 percent of the total investment cost per
year. Specific chemical-use costs were added when such materials
were consumed in the waste treatment system. By-product income,
relative to waste treatment was credited only in the irrigation
system for 13,400 kg (29,480 Ib) of dry matter (hay or grass) per
hectare at $22 per 100 kg of hay with two crops per year. This
136
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is equivalent to a yield of six tons per acre valued at $20 per
ton of dry hay.
ENERGY REQUIREMENTS
The electrical energy consumption by the meat processing industry
was reported for 1967 at 646 million KWH and total heat and power
consumption at 4718 KWH.2 The meat processing industry consumes
relatively small quantities of electrical energy, but large
quantities of fuel for cooking meat products. The waste
treatment systems require power primarily for pumping and
aeration. The aeration horsepower is a function of the waste
load, and that for pumping depends on waste water flow rate.
Total power consumption for current waste treatment, which will
substantially be the consumption for 1977 limitations, is
estimated to be about 50 million KWH per year for the meat
processing industry. This amounts to 8.0 percent of the
industry's electrical energy consumption and 1.1 percent of total
energy consumption reported for 1967, and approximately 1.4
percent of current total energy consumption. The additional
power consumption to achieve 1983 limitations amounts to two
percent of electrical energy and 3.0 percent of total energy;
this does not appear to raise serious power supply or cost
questions for the industry. However, the widespread use of
chlorine as a disinfectant may pose some energy problems in the
future, or, conversely, the future supply of chlorine may be
seriously affected by the developing energy situation.
Waste treatment systems impose no significant addition to the
thermal energy requirements of plants. Waste water can be reused
in cooling and condensing service if it is kept separate from the
process waters. Heated waste waters improve the effectiveness of
anaerobic ponds which are best maintained at 32°C (90°F) or
higher. Improved thermal efficiencies are coincidentally
achieved within a plant when waste water is reused in this
manner.
Waste water treatment costs and effectiveness can be improved by
the use of energy and power conservation practices and techniques
in the processing plant. The waste load increases with increased
water use. Reduced water use therefore reduces the waste load,
pumping costs, and heating costs, the last of which can be
further reduced by water reuse, as suggested previously.
NONWATER POLIUTION BY WASTE TREATMENT SYSTEMS
Solid Wastes
Solid wastes are the most significant nonwater pollutants
associated with the waste treatment systems applicable to the
137
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meat processing industry. Screening devices of various design
and operating principles are used primarily for removal of large
solids from waste water. These solids may have some economic
value as inedible rendering material, or they may be land filled
or spread with other solid wastes.
The solids material separated from the waste water stream which
contains organic and inorganic matter, and the chemicals added to
aid solids separation are called sludge. Typically, sludge
contains 95 to 98 percent water before dewatering or drying.
Both primary and secondary treatment systems generate some
quantity of sludge; the quantity will vary by the type of system
as shown by the general estimates in Table 17.
The raw sludge can be concentrated, digested, dewatered, dried,
incinerated, land filled on site, or spread in sludge holding
ponds. The sludge from any of the treatment systems, except air
flotation with polyelectrolyte chemicals added, is amenable to
any of these sludge handling processes.
Table 17. Sludge Volume Generation
by Waste Treatment Systems
Treatment System
Dissolved air flotation
Anaerobic lagoon
Aerobic and aerated lagoons
Activated sludge
Extended aeration
Anaerobic contact process
Rotating biological contactor
Sludge Volume as Percent of Raw
Wastewater Volume
Up to 10%
Sludge accumulation in these
lagoons is usually not sufficient
to require removal at any time.
10 - 15%
5 - 10%
Approximately 2%
Unknown
The sludge from air flotation with chemicals addition has been
difficult to dewater. A dewatered sludge is an acceptable land
fill material. Sludge from secondary treatment systems is
normally ponded by meat industry plants on their own land or
dewatered or digested sufficiently for hauling and deposition in
public land fills. The final dried sludge material can be safely
used as an effective soil builder. Prevention of run-off is a
critical factor in plant-site sludge holding ponds. Costs of
typical sludge handling techniques for each secondary treatment
system generating sufficient quantities of sludge to require
handling equipment are included in the costs for these treatment
systems.
138
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Air Pollution
Odors are the only significant air pollution problem associated
with waste treatment in the meat processing industry. Malodorous
conditions usually occur in anaerobic waste treatment processes
or localized anaerobic environments within aerobic systems.
However, it is generally agreed that anaerobic ponds will not
create serious odor problems unless the process water has a
sulfate content; then it most assuredly will. Sulfate waters are
definitely a localized condition, varying even from well to well
within a specific plant. In northern climates, the change in
weather in the spring may be accompanied by a period of increased
odor problems.
The anaerobic pond odor potential is somewhat unpredictable as
evidenced by a few plants that have odor problems without sulfate
waters. In these cases a cover and collector of the off-gas from
the pond controls odor. The off-gas is burned in a flare.
The other potential odor generators in the waste water treatment
are leaking tanks and process equipment items used in the
anaerobic contact process involving methane generation. However,
with the process confined to a specific piece of equipment it is
relatively easy to confine and control odors by collecting and
burning the off-gases. The high heating value of these gases
makes it worthwhile, and a frequent practice, to recover the heat
for use in the waste treatment process.
Odors have been generated by some air flotation systems which are
normally housed in a building, thus localizing, but intensifying
the problem. Minimizing the unnecessary holdup of any skimmings
or grease-bearing solids has been suggested as a remedy. Odors
can best be controlled by elimination at the source, rather than
resorting to treatment for odor control, which remains largely
unproven at this time.
Noise
The only material increase in noise within a processing plant
caused by waste treatment is that caused by the installation of
an air flotation system or aerated lagoons with air blowers.
Large pumps and an air compresser are part of an air flotation
system. The industry normally houses such a system in a low^cost
building; thus, the substantial noise generated by an air
flotation system is confined, but perhaps amplified, by
installation practices. All air compressors, air blowers, and
large pumps in use on intensively aerated treatment systems, and
other treatment systems as well, may produce noise levels in
excess of the Occupational Safety and Health Administration
standards. The industry must consider these standards in solving
its waste problems.
139
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SECTION IX
EFFLUENT REDUCTION ATTAINABLE THROUGH THE APPLICATION
OF THE BEST PRACTICABLE CONTROL TECHNOLOGY
CURRENTLY AVAILABLE—EFFLUENT LIMITATIONS GUIDELINES
INTRODUCTION
The effluent limitations which must be achieved no later than
July 1, 1977, are to specify the degree of effluent reduction
attainable through the application of the Best Practicable
Control Technology Currently Available. Best Practicable Control
Technology Currently Available is generally based upon the
average of the best existing performances by plants of various
sizes, ages, and unit processes within the industrial category
and/or subcategory.
In the meat processing industry, on-site waste water treatment is
relatively uncommon; based on our survey, 80 to 90 percent of the
plants in each subcategory discharge to municipal systems. Thus,
the determination of best existing performance is based on that
achieved by one or two plants in each subcategory or on transfer
of technology from the meat packing industry, and expert opinion.
Consideration is also given to:
o The total cost of application of technology in relation
to the effluent reduction to be achieved from such
application and the financial capabilities of the
typical plant in the subcategory;
o The size and age of equipment and facilities involved;
o The process employed;
o The engineering aspects of the application of various
types of control techniques;
o Process changes;
o Nonwater quality environmental impact (including
energy requirements) .
Also, Best Practicable Control Technology Currently Available
emphasizes treatment facilities at the end of a manufacturing
process, but includes the control technologies within the
processing plant when the latter are considered to be normal
practice within an industry.
A further consideration is the degree of economic and engineering
reliability which must be established for the technology to be
"currently available." As a result of demonstration projects,
pilot plants, and general use, there must exist a high degree of
147
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confidence in the engineering and economic practicability of the
technology at the time of start of construction of the control
facilities.
EFFLUENT REDUCTION ATTAINABLE THROUGH THE APPLICATION OF BEST
PRACTICABLE CONTROL TECHNOLOGY CURRENTLY AVAILABLE
Based on the information contained in Sections III through VIII
of this report, a determination has been made that the quality of
effluent attainable through the application of the Best
Practicable Control Technology Currently Available is as listed
in Table 18. In the North Star sample, all of the small
processors that handle their own waste water meet the proposed
standard. Five plants in the four large processing subcategories
report having their own secondary treatment and four of these
plants meet the proposed BOD.5 limitations.
IDENTIFICATION OF BEST PRACTICABLE CONTROL
TECHNOLOGY CURRENTLY AVAILABLE
The best practicable control technology currently available for
the meat processing industry is a function of plant size and
subcategory as follows:
Small processors 2730 kg (6000 Ib) per day of FP or less,
septic tank(s) and underground drainage
system (cesspool or drain field)
Large processors more than 2730 kg (6000 Ib) per day of FP,
biological waste treatment following
in-plant removal of solids and grease from
the waste water
To assure that the biological treatment will successfully achieve
the specified limits for large processors, certain in-plant
practices should be as follows:
1, Reduce water use by shutting off water when not needed,
by always using extensive dry cleanup of floors before
washing with water, and by exercising attentive
management control over housekeeping and water use
practices. A reduction in water use will result in a
reduction in waste load. The following figures are the
averages of water use by plants in each subcategory, and
could be considered "typical." Rates above these should
be reduced through special attention to in-plant
practices.
142
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Table 18. Recommended Effluent Limitations, July 1, 1977
CO
Industry
Subcategory
_
Meat Cutters
Sausage and
Luncheon Meat
Processors
Ham Processors
Meat Canners
BOD5
kg/kgg FP
or lb/1000 lb
0.015
0.24
0.27
0,33
Suspended
Solids
kg/kkg FP
or lb/1000 lb
, ,
0.018
0.29
0.32
0.40
Grease
kg/kkg FP
or lb/1000 lb
0.006
0.10
0.11
0.13
Fecal Coliform
Max. Count /100 ml
400
400
400
400
-------
Subcategory
Liters/kkq FP
Small processors 3.335
Meat, cutters 600
Sausage and luncheon 9,600
meats processors
Ham processors
Meat canners
10,600
11,250
Gal./lOOO Ib FP
400
70
1150
1270
1350
2. In-plant recovery or removal of waste material should
include, at a minimum, a gravity catch basin with at
least a 30-minute detention time. This catch basin
should be cleared of solids and grease on a
daily basis.
3, Noncontaminated cooking water and cooling water from
processing or auxiliary equipment should not be
discharged through the in-plant waste recovery of the
biological waste treatment system.
The preceding in-plant practices, in addition to good
housekeeping, can produce a raw waste load below that cited as
average for each subcategory in Section V. The following
biological treatment systems are adequate to achieve the
suggested standards with an average raw waste load:
1. Extended aeration + aerobic (shallow) lagoon
2. Activated sludge + extended aeration
3. Anaerobic lagoon + aerobic (shallow) lagoon
4. Aerated lagoon + aerobic (shallow) lagoon
A clarification pond may be required prior to final discharge for
plants in certain location, and climates. Disinfection, perhaps
by chlorination, may be necessary to achieve the fecal coliform
limitation.
RATIONALE FOR THE SELECTION OF BEST PRACTICABLE
CONTROL TECHNOLOGY CURRENTLY AVAILABLE
Age and Size of Equipment and Facilities
The industry has generally modernized its plants as new economic
methods have been introduced. No relationship between age of
plant and effectiveness of its pollution control was found.
144
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Size of plant is a basis for categorization with the division
between large and small processors found to be 2730 kg (6000 Ib)
per day of FP. All ten of the small processor plants that treat
their own waste water use septic tanks with or without drain
fields and thereby achieve the recommended limitation of no
discharge. Because the output of products per plant from this
subcategory is small, only small quantities of water are
required, and this is usually only in cleanup. Thus, the
limitation is reasonable, based on industry practice and on the
feasibility of no discharge with the low average waste water
volume from a typical plant in the subcategory.
The variation in size of plants in the other four subcategories
is not a significant factor in terms of waste water treatment
capability. Neither water use nor raw waste load were found to
be related directly to production output or size of plant.
The processes employed in the industry are basically similar for
large and small plants and are dependent, instead, on the product
mix. The practicable control technology is affected only by the
different raw waste concentrations that apparently occur as a
result of the production of different products. These differing
waste concentrations require somewhat different treatment
techniques, which are described in greater detail in the
discussion on engineering aspects of control technology.
Total Cost of Application
Based on the information contained in Section VIII of this
report, the industry as a whole would have to invest about $2.5
million to achieve the recommended effluent limitations. The
data and information available on the industry indicate a need,
in general, only to upgrade the operating performance of the
treatment systems in use and to add chlorination. No plant was
found in the survey that will have to add any treatment process
other than chlorination to its existing system. The operating
performance of the treatment systems will require improvement in
some cases, but the installed treatment technology, with
chlorination, should be adequate. One way to improve this
operating performance would be to add an employee to devote part-
time to the in-plant recovery system and to the biological
treatment system. This, plus chlorination, could mean an
addition to plant operating costs of up to $20,000 per year.
Engineering Aspects of control Technique Applications
The specified level of technology is practicable; the required
technology is in use by plants within the meat processing
industry and by plants in the meat packing industry where the raw
waste composition and concentration is comparable.
145
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Small Processors The control technology specified for the small
processors to achieve the proposed no discharge limitation
involves the use of septic tanks and drain fields. This
technology results in no waste water discharge from a small
processor into a receiving body of water. The technology is
basic and is practiced by all of the small processors in the
North star sample who treat their own waste water. The sole
consideration appears to be volume of water to be treated, and
the average of 840 gallons per day would be comparable to the
waste water volume from two average sized families. The septic
tank-drain field technology is clearly well established and in
widespread use on volumes of waste water comparable to those from
the small processing plants.
Large Processors
The other four subcategories within the industry are included in
the large processor group. Of the 63 plants in this group that
responded to the survey questionnaire, only five reported having
their own waste water treatment systems. One of these five
plants irrigated virtually treated effluent with no run-off and
thereby achieved a level of treatment equal to no discharge.
The small number, but wide variety, of treatment systems in use
by the meat processing industry meant that the data base was
minimal for establishing achievable limitations for each
subcategory. There was only the experience of one or two plants
from which to draw. However, the typical meat processing waste
water composition and concentration were very similar to those
characteristics of the waste water from much of the meat packing
industry. While the limitations are proposed on the basis of
actual meat processing plant waste treatment performance, the
meat packing industry experience in waste water treatment
supports the limitations. The transfer of technology within a
single industry group such as meat products is technically sound
and not at all speculative.
The transfer of control technology from the meat packing industry
was used to determine a limiting concentration for a waste
component in the final effluent. Six meat packing plants using
the suggested waste treatment technology achieved final effluent
BOD!) concentrations of 25 milligrams per liter or less.
Literature sources and expert opinion suggest that concentrations
become limiting in the range of 20 to 30 milligrams per liter for
BOD5 in the final effluent from the suggested treatment
technology. Thus, subject to other consideration, the limiting
BOD5 concentration was set at 25 mg/liter for the "typical" plant
final effluent quality. The limiting suspended solids
concentration was set at 1.2 times the BOD5 concentration; again,
subject to other considerations; and likewise, the grease
effluent concentration limit was set at 10 mg/1.
A second limitations constraint based on meat packing plant waste
treatment experience was the overall removal effectiveness
146
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required of a treatment system on a specific waste component.
These data were presented previously, in Sections VII and VIII.
Meat Cutters
There is one plant in the sample of this subcategory with a waste
treatment system. The treatment system includes a sand filter,
which is considered a tertiary treatment device. This plant has
an effluent that is of better quality than the concentration-
based limitations proposed for this subcategory for each waste
component. The proposed limitations for a typical plant reflect
an effluent quality that is routinely met or exceeded by the
performance of this one plant because best practicable technology
cannot achieve a comparable final effluent, given the average raw
waste for the sufccategory.
Sausage and Luncheon Meat Processors
The sample of plants in this subcategory that responded to the
survey questionnaire includes no plants with their own waste
water treatment. The effluent limitations were therefore set at
the concentration limiting level. Treatment effectiveness was
computed with these limitations as a percent of the average raw
waste load for the subcategory and was found to be technically
acceptable.
Ham Processors
This subcategory includes the meat processing plant in California
that irrigates cotton fields with treated effluent. There is no
run-off from the irrigation system. There are also two plants in
the sample of this subcategory that treat their own waste water.
One plant has a final effluent of better quality than the
proposed limitations which are set at the concentration limit for
each parameter; the other plant has an effluent not within the
standard.
Meat Canners
There is only one plant in the sample of this subcategory with
its own waste water treatment system. The proposed BOD5.
limitation, as defined on a normalized basis of kg per kkg of
finished product, is equal to the BOD5 content in the final
effluent from this one plant. This level of performance is
reasonable, as measured by the percent removal required for the
"typical" plant in the subcategory at the average raw waste load,
and as indicated by the fact that the one plant in the sample
with treatment meets the standard.
147
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The proposed limitations on the other components of the waste
stream-suspended solids and grease—are set as previously
described at 1.2 times BOD5 for suspended solids and 10 mg/1 for
grease. The plant in this subcategory with waste treatment also
meets these limitations.
Process Changes
No in-plant changes will be needed by most plants to meet the
limits specified. Most plants will need to improve water
conservation practices and housekeeping, both requiring insistent
plant management and control.
Nonwater Quality Environmental Impact
The major impact, when the option of an activated sludge-type
process is used to achieve the limits, will be the problem of
sludge disposal. Nearby land for sludge disposal may be
necessary; in some cases a sludge digester (stabilizer) may offer
a solution. Properly operated activated sludge-type systems
should permit well-conditioned sludge to be placed in small
nearby plots for drying without great difficulty.
Potential problems with anaerobic lagoons are the periodic or
occasional odor emission and the spring break-up of ice with the
resultant lagoon mixing and high load in the effluent. Both
problems can be controlled if anticipated and planned for,
including the collection and burn-off of the odorous gases and
the proper sizing of the lagoons for winter operation in northern
climates. Avoidance of high sulfate fresh water supplies is
necessary to prevent lagoon odors; totally aerobic systems are
also effective for avoiding odors.
The energy situation is a serious consideration in waste
treatment at this time and undoubtedly will be in the future.
The aerated lagoon and extended aeration techniques consume more
power than the other approaches. It may be the best choice to
exchange power consumption for land, whenever this option is
available; i.e., the use of extensive, perhaps oversized, aerobic
lagoons to achieve the same result as a small aerated lagoon, or
irrigation of the land with waste water to raise crops. The
dollar cost of energy does not reflect the comparative supply and
demand situation, particularly in comparison with other plant
costs. However, management in the industry will undoubtedly be
thoroughly aware of the energy situation in considering waste
treatment alternatives.
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SECTION X
EFFLUENT REDUCTION ATTAINABLE THROUGH THE APPLICATION
OF THE BEST AVAILABLE TECHNOLOGY ECONOMICALLY
ACHIEVABLE—EFFLUENT LIMITATIONS GUIDELINES
INTRODUCTION
The effluent limitations which must be achieved no later than
July 1, 1983, are not based on an average of the best performance
within an industrial category, but are determined by identifying
the very best control and treatment technology used by a specific
point source within the industrial category or subcategory, or by
one industry where it is readily transferable to another. A
specific finding must be made of the availability of control
measures and practices to eliminate the discharge of pollutants,
taking into account the cost of such elimination.
Consideration must also be given to;
o The age of the equipment and facilities involved;
o The process used;
o The engineering aspects of the application of various
types of control techniques;
o Process changes;
o The cost of achieving the effluent reduction resulting
from application of the technology;
o Nonwater quality environmental impact (including energy
requirements).
Also, Best Available Technology Economically Achievable
emphasizes in-process controls as well as control or additional
treatment techniques employed at the end of the production
process.
This level of technology considers those plant processes and
control technologies which, at the pilot-plant, semi-works, and
other levels, have demonstrated both technological performance
and economic viability sufficient to reasonably justify investing
in such facilities. It is the highest degree of control
technology that has been achieved or has been demonstrated to be
feasible for plant-scale operation/ up to and including "no
discharge" of pollutants. Although economic factors are
considered in this determination, the costs for this level of
control will be the maximum for currently available technology,
as previously defined, and within the financial capability of the
industry. However, there is some uncertainty with respect to
technical performance and even more so with respect to the cost
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Table 19. Recommended Effluent Limitations for July 1, 1983
01
o
Industry
Subcategory
Small
Processors
Meat
Cutters
Sausage and
Luncheon
Meats
Processors
Ham
Processors
Meat
Canners
BOD5
kg/kkg FP
0.009
0.14
0.16
0.17
Suspended
Solids
kg/kgg FP
0.012
0.19
0.21
0.22
Grease
mg/1
5
5
5
5
Waste Pa
Total
Kjeldahl
Nitrogen
mg/1
4
4
4
4
rameters
Ammonia
mg/1
4
4
4
4
Phosphorus
mg/1
2
2
2
2
Nitrate,
Nitrite
mg/1
0.5,0.5
0.5,0.5
0.5,0.5
0.5,0.5
Fecal
Coliform
Count/100 ml
400
400
400
400
-------
estimates. Therefore, some industrially sponsored development
work and cost refinement may be needed prior to application of
any specific technology not in current use.
EFFLUENT REDUCTION ATTAINABLE THROUGH APPLICATION OF THE
BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE
Based on the information contained in Sections III through VIII
of this report, a determination has been made that the quality of
effluent attainable through the application of the Best Available
Technology Economically Achievable is as listed in Table 19. The
technology to achieve these goals is generally available,
although it may not yet have been applied specifically to meat
processing plant waste or on a full scale.
It should be pointed out that a meat processor should seriously
consider land disposal, and hence no discharge, for 1983. Where
suitable land is available, evaporation or irrigation is an
option that not only is recommended from the discharge viewpoint,
but also will usually be more economical than the system
otherwise required,
IDENTIFICATION OF THE BEST AVAILABLE TECHNOLOGY
ECONOMICALLY ACHIEVABLE
The Best Available Technology Economically Achievable includes
that listed under the Best Practicable Control Technology
Currently Available. In addition, it includes improved
pretreatment, such as dissolved air flotation with pH control and
chemical flocculation; an ammonia control step which may involve
ammonia stripping or a nitrification-denitrification sequence;
and a sand filter or equivalent following biological treatment.
In-plant controls and modifications are also required to achieve
the specified levels. These include:
o Water control systems and procedures to reduce water
use to about 50 percent of that listed in Section IX,
except for small processors;
o Reduction in the waste water resulting from thawing
operations;
o Provision for improved collection and greater reuse
of pickle and cure solutions;
Prepackaging products (e.g., hams) before cooking
and smoking to reduce grease contamination of smoke-
house floors and walls;
Revision of equipment cleaning procedures to collect
and reuse wasted materials, or to dispose of them
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through channels other than the sewer;
o Initiation and continuous enforcement of meticulous
dry cleanup of floors before washing;
o Installation of properly designed catch basins and
maintenance of them with frequent, regular grease
and solids removal.
To reduce the water use to the required levels, several changes
in normal plant operations may be required. Push-to-open valves
need to be used wherever possible. Spray nozzles can be
redesigned for lower water flow. Automatic valves that close
when the water is not in use should be installed. Preliminary
dry cleanup of the floors will reduce water used in floor
washing.
Water reuse should be maximized, by recycling, or reusing water
for lower quality needs. Noncontaminated water should always be
reused or recycled, after any necessary appropriate intermediate
treatment. If this noncontaminated water is wasted, it should
not be mixed with the contaminated waste water from the plant
upstream of the waste treatment facility.
Dissolved solids can be minimized by changing some current
practices. Excess cure solutions should be collected and
treated, if necessary, for reuse; they should not be dumped.
Salt should not be used on floors as an antislip material; other
methods and plant practices are available to counteract this
problem.
If suitable land is available, land disposal is the best
technology; it achieves a treatment level of no discharge.
Depending on the amount and type of land, the above in-plant
techniques and primary treatment may be adequate before
discharging to the land. In some locations, a secondary
treatment system may be required before disposal on the land.
Any of the systems mentioned in Section IX, or even simpler ones,
are suitable. The potential problem of dissolved solids in
irrigation systems can usually be avoided by minimizing dissolved
solids as described above; in some cases a part of the stream may
need to be treated by ion exchange.
The technology is available and in use by the small processors
for no discharge via the use of septic tanks with underground
drainage using a drain field. Strict in-plant controls are
readily managed in the small plant to minimize the raw waste
load.
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RATIONALE FOR SELECTION OF THE BEST AVAILABLE
TECHNOLOGY ECONOMICALLY ACHIEVABLE
Age of Equipment and Facilities
The age of plants and equipment do not affect the end~of-process
pollution control effectiveness. Although in-plant control can
be managed quite effectively in older plants, some of the
technologies required for reducing the raw waste loads to
realistically low levels may be more costly to install in older
plants.
Total Cost of Application in Relation to
Effluent Reduction Benefits
Based on information contained in Section VIII of this report,
the total investment cost to the industry will be between $33 and
$60 million to achieve the 1983 limitations. This investment
cost will involve only the large processors because the small
processors already meet the 1983 level with their present
treatment technology. This approximate total investment cost
amounts to between $160 and $280 per kkg of annual installed
production capacity ($75 to $125 per 1000 Ib per year). It also
amounts to between 10 and 18 percent of the estimated total
capital spending--$347 million—by the large processors over the
last ten years; 1963 through 1972.
The additional operating cost for the more complete waste water
treatment required for 1983 amounts to between 0.30 and 1.1* per
kg FP (0.140 to 0.540 per Ib FP) depending on the subcategory and
how extensive the additional treatment system is. The unit cost
of waste treatment will be lower for larger plants because most
of the operating costs are fixed rather than variable costs.
All plants discharging to receiving bodies of water can implement
the Best Available Technology Economically Achievable; the
technology is not affected by different processes used in plants
throughout the meat processing industry.
Engineering Aspects of Control Technique Application
The specified level of effluent is achievable. It is presently
being met for all pollutants, except nitrates, by at least one
plant in the industry. Typically, newer technology is being used
by the plant or they are especially careful in their plant
operations.
Phosphorus is effectively removed by chemical treatment in air
flotation, and by filtration of the final effluent from secondary
treatment. The greatest unknown is the nitrification-
denitrification step.
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However, nitrification has been achieved in pilot units and to a
limited extent in plant operations. Denitrification has been
explored with some success on laboratory and pilot scales.
Ammonia stripping may require pH adjustment and later
neutralization; it is a technology transferred from other
industries.
Each of the identified technologies, except ammonia removal and
nitrif ication-rdenitrification, is currently being practiced in
the meat products industry. They need to be combined, however,
to achieve the limits specified.
Technology for land disposal by irrigation is being used by meat
processing and meat packing plants in the Southwest and
California. It is being planned for a packing plant in Iowa.
Other industries, e.g., potato processing, are using it
extensively. Secondary treatment and large holding ponds may be
required in the North for land disposal during about one-half of
the year. Application of technology to reduce in-plant water use
will facilitate land disposal alternatives.
Process Changes
In-plant changes will be needed by most plants to meet the limits
specified. These were outlined in the "Identification of the
Best Available Technology Economically Achievable," above.
Nonwater Quality Impact
None of the additional technology required to meet the 1983
limitations is energy intensive. The primary energy consumption
occurs in pumping the waste water and the other material streams
in the treatment processes.
The major impact will occur when the land disposal option is
chosen. The potential long-term effect on the soil caused by
irrigation of processing plant wastes is unknown. It has been
done successfully by one California plant for over 3C years. The
impact will probably depend on location, soil conditions, waste
strength, climate and other factors and relationships which have
yet to be determined.
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SECTION XI
NEW SOURCE PERFORMANCE STANDARDS
INTRODUCTION
The effluent limitations that must be achieved by new sources are
termed performance standards. The New Source Performance
Standards apply to any source for which construction starts after
the prcrmilgaticn arid publication of the proposed regulations as
Standards. The standards are determined by adding to the
consideration underlying the identification of the Best
Practicable Control Technology Currently Available, a
determination of what higher levels of pollution control are
available through the use of improved production processes and/or
treatment techniques. Thus, in addition to considering the best
in-plant and end-of-process control technology. New Source
Performance Standards are based on an analysis of how the level
of effluent may be reduced by changing the production process
itself. Alternative processes, operating methods, or other
alternatives are considered. However, the end result of the
analysis is to identify effluent standards which reflect levels
of control achievable through the use of improved production
processes and practices (as well as control technology), rather
than prescribing a particular type of process or technology which
must be employed. A further determination is made whether a
standard permitting no discharge of pollutants is practicable.
Consideration must also be given to:
o Operating methods;
o Batch, as opposed to continuous, operations;
o Use of alternative raw materials and mixes of
raw materials;
o Use of dry rather than wet processes (including
substitution of recoverable solvents for water);
o Recovery of pollutants as by-products.
EFFLUENT REDUCTION ATTAINABLE FOR NEW SOURCES
The effluent limitation for new sources is the same as that for
the Best Practicable Control Technology Currently Available (see
Section IX). This limitation is readily achievable in newly
constructed plants. However, the limitations for the Best
Available Technology Economically Achievable should be kept in
mind; it may be a more practical approach to design a plant which
approaches the 1983 limitations. Consideration should also be
given to land disposal, which would be no discharge; in many
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cases this will be the most attractive and economical option.
Estimates of capital investment cost, operating cost, and total
annual cost for waste treatment by new point sources are listed
for each subcategory in Table 20.
IDENTIFICATION OF NEW SOURCE CONTROL TECHNOLOGY
The technology is the same as that identified as the Best
Practicable Control Technology Currently Available (see Section
IX). However, certain steps that will be necessary to meet the
1983 guidelines should be considered and, where possible,
incorporated. These include:
In-plant Controls
o water control systems and procedures to reduce water
use considerably below that cited in Section IX,
except for small processors;
o Reduction in the waste water from thawing operations;
o Provision for improved collection and greater reuse
of cure and pickle solutions;
o Prepackaging products (e.g., hams) before cooking to
reduce grease contamination of smokehouse floors and
walls;
o Revision of equipment cleaning procedures to collect
and reuse wasted materials, or to dispose of them
through channels other than the sewer;
o Noncontaminated water should be reused or recycled
whenever possible;
o Initiation and continuous enforcement of meticulous
dry cleanup of floors before washing;
o Installation of properly designed catch basins and
maintenance with frequent regular grease and solids
removal;
End-of-process Treatment
o Land disposal (evaporation, irrigation) wherever possible;
this should be a primary consideration;
o Sand filter or microscreen for biological treatment of
effluent;
o Solid waste drying, composting, and upgrading of protein
content.
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PRETREATMENT REQUIREMENTS
No constituents of the effluent discharged from a plant within
the meat processing industry have been found which would
interfere with, pass through, or otherwise be incompatible with a
well—designed and operated, publicly owned activated sludge or
trickling filter waste water treatment plant. The effluent,
however, should have passed through materials recovery (primary
treatment) in the plant to remove settleable solids and a large
part of the grease. The concentration of pollutants acceptable
to the municipal treatment plant is dependent on the relative
sizes of the treatment facility and the meat processing plant,
and must be established by the treatment facility. It is
possible that grease remaining in the processing plant effluent
will cause difficulty in the treatment system; trickling filters
appear to be particularly sensitive. A concentration of 100 mg/1
is often cited as a limit, and this may require an effective air
flotation system in addition to the usual catch basin. If the
waste strength, in terms of BODj>, must be further reduced, any of
the various components of secondary treatment systems can be
used, such as anaerobic contact, trickling filter, aerated
lagoons, etc., as pretreatment.
Table 20. Capital Investment,* Operating and
Total Annual Costs for New Point
Sources
Costs
Total
Capital
Investment,
Average
Plant
Operating
Cost per
Year
Total
Annual
Cost
per Year
Sub category
Small
Processor
$5000
200
1200
Meat
Cutter
$60,000
14,800
26,600
Sausage and
Luncheon Meats
Processor
$130,000
20,300
44,500
Ham
Processor
$115,000
19,100
-
41,100
Meat
Canner
$190,000
25 , 800
61,400
*Capital investment cost based on aerated lagoon plus aerobic lagoon
treatment system, except small processors.
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SECTION XII
The program was conducted under the overall supervision of Dr. E.
E, Erickson. Robert J. Reid was the Project Engineer; he was
assisted by Messrs. J. P. Pilney and Robert J. Parnow. special
assistance was provided by North Star staff members: Mrs. Janet
McMenamin, Messrs. R. H. Forester and A. J. Senechal, and Dr. L.
L, Altpeter.
The contributions and advice of Mr. A. J. Steffan of Purdue
University, Mr. W. H. Miedaner of Globe Engineering, and Dr. H.
O. Halverson are gratefully acknowledged. Also, James and Paula
Wells of Bell, Galyardt, and Wells made invaluable contributions
in numerous telephone conversations.
Special thanks are due Mr. Jeffery D. Denit, Effluent Guidelines
Division, for his guidance in the direction of the program and
for his invaluable help in carrying out all aspects of the
research program.
The help of Dr. Dwight Ballinger of EPA in Cincinnati in
establishing The American Association of Meat Processors, The
American Meat Institute, the National Independent Meat Packers
Association, and the Western states Meat Packers Association
deserve special mention, as do many companies that provided
information and cooperation in plant visits and on-site sampling
programs.
Th help of Dr. Dwight Ballinger of EPA in Cincinnati in
establishing sampling and testing procedures used for the field
verification studies was also appreciated.
Various offices in the United states Department of Agriculture,
especially the Meat and Poultry Inspection Division, and many
state and local agencies were also helpful and much appreciated.
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SECTION XIII
REFERENCES
1. Standard Industrial Classification Manual, Executive Office
of the President, Office of Management and Budget, U.S.
Government Printing Office, Washington, 1972.
2. 1967 Census of Manufactures, Bureau of the Census, U.S.
Department of commerce, U.S. Government Printing Office,
Washington, 1971.
3. "F.I. Plants Are up 900 for Fiscal Year But Drop Outside
USDATapped States," The National Provisioner (August 25,
1973).
4. U.S. Industrial Outlook, 1974, with Projections to 1980, U.S.
Department of Commerce, U.S. Government Printing Office,
Washington.
5. The Cost of Clean Water, Industrial Waste Profile No. 8, Meat
Products, U.S. Department of the Interior, Federal Water
Pollution Control Administration, U.S. Government Printing
Office, Washington.
6. Personal communication with W. Miedaner, January 1974.
7. Basics of Pollution Control, Gurnham & Associates, prepared
for Environmental Protection Agency Transfer Program, Kansas
City, Mo., March 7-8, 1973, Chicago, Illinois.
8. Public Health Service Drinking Water Standards, Revised 1962,
U.S. Department of Health, Education and Welfare, U.S. Public
Health Service Publication No. 956, U.S. Government Printing
Office, Washington, 1962.
9. Development Document for Proposed Effluent Limitations
Guidelines and New Source Performance standards for the Red
Meat Processing Segment of the Meat Product and Rendering
Processing Point Source Category, U.S. Environmental
Protection Agency, Report No. 440/1-73/ 012, Washington,
October 1973.
10. Miedaner, W.J., "In*Plant Waste Control,» The
Provisioner (August 19, 1972).
National
11. Steffan, A.J., "In-Plant Modifications to Reduce Pollution
and Pretreatment of Meat Packing Wastewaters for Discharge to
Municipal Systems," prepared for Environmental Protection
Agency Technology Transfer Program, Kansas City, Mo., March
7-8, 1973.
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12. Water Quality Improvement by Physical and Chemical Processes,
Earnest F. Gloyna and W. Wesley Eckenfelderr Jr., Eds,,
University of Texas Press, Austin, 1970.
13. Rosen, G.D., "Profit from Effluent," Poultry Industry (April
1971).
14. Personal communication with J. Hesler, Greyhound Corporation,
1973.
15. Telephone communication with M. Hartman, Infilco Division,
Westinghouse, Richland, Virginia, May 1973.
16, Upgrading Meat Packing Facilities to Reduce Pollution: Waste
Treatment Systems, Bell, Galyardt, Wells, prepared for
Environmental Protection Agency Transfer Program, Kansas
City, Mo., March 7-8, 1973, Omaha.
17. Private communication from Geo* A. Hormel & Company, Austin,
Minnesota, 1973.
18. Chittenden, Jimmie A., and Wells, W. James, Jr., "BOD Removal
and Stabilization of Anaerobic Lagoon Effluent Using a
Rotating Biological Contactor," presented at the 1970 Annual
Conference, Water Pollution Control Federation, Boston.
19. Gulp, Russell L., and Gulp, Gordon L., Advanced Wastewater
Treatment, Van Nostrand Reinhold Company, New York, 1971.
20. Babbitt, Harold E., and Baumann, E. Robert, Sewerage and
Sewage Treatment, Eighth Ed., John Wiley & Sons, Inc.,
London, 1967.
21. Fair, Gordon Maskew, Geyer, John Charles, and Okun, Daniel
Alexander, Water and Wastewater Engineering: Volume 2. Water
Purification and Wastewater Treatment and Disposal, John
Wiley & Sons, Inc., New York, 1968.
22. Personal communication with H.O. Halvorson, 1973.
23. Fair, Gordon Maskew, Geyer, John Charles, and Okun, Daniel
Alexander, Water and Wastewater Engineering: Volume 1, Water
Supply and Wastewater Removal, John Wiley & Sons, Inc., New
York, 1966.
24. Eckenfelder, W. Wesley, Jr., Industrial Water Pollution
Control, McGraw-Hill Book Company, New Yorkr 1966.
25. Eliassen, Rolf and Tchobanoglous, George, "Advanced Treatment
Processes," Chemical Engineering (October 14, 1968).
26. Knowles, Chester L., Jr., "Improving Biological Processes,"
Chemical Engineering/Deskbook Issue (April 27, 1970).
27. Personal communication, H.O. Halvorson, May 1973.
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28. Witherow, Jack L., Small Meat Packers Wastes Treatment
Systems, Presented at 4th National Symposium on Food
Processing Wastes, Syracuse, N.Y., March 26-28, 1973.
29. Pilot Plant Installation for Fungal Treatment of Vegetable
Canning Wastes, The Green Giant Company for Environmental
Protection Agency, Grant No. 12060 EDZ, August 1971.
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30. Personal communication, C.E. Clapp, United States Department
of Agriculture, Agricultural Research Service, University of
Minnesota, Minneapolis, May 1973.
31. Financial Facts About the Meat Packing Industry, 1971,
American Meat Institute, Chicago, August 1972.
32. "Survey of Corporate Performance: First
Business Week, p. 97 (May 12, 1973).
Quarter
1973,"
164
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"Act":
1972.
SECTION XIV
GLOSSARY
The Federal Water Pollution Control Act Amendments of
Activated Sludge Process: Aerated basin in which waste waters
are mixed with recycled biologically active sludge for periods of
about six hours.
Aerated:
liquid by
bubbling.
The introduction and immediate contacting of air and a
mechanical means, such as stirring, spraying, or
Aerobic: Living or occurring only in the presence of dissolved
or molecular oxygen.
Algae: Major groups of lower plants, single and multicelled,
usually aquatic and capable of synthesizing ^their foodstuffs by
photosynthesis.
Ammonia Stripping: Ammonia removed from a liquid, usually by
immediate contact with an ammonia-free gas such as air.
Anaerobic: Living or active only in the absence of free oxygen.
Bacteria: Primitive plants, generally free of pigment, which
reproduce by dividing into one,two or three planes. They occur
as single cells, chains, filaments, well-oriented groups or
amorphous masses. Most bacteria do not require light, but a
limited number are photosynthetic and draw upon light for evergy.
Most bacteria are heterotrophic (use organic matter for energy
and for growth materials), but a few are autotrophic and derive
their bodily needs from inorganic materials.
Biodegradable: The condition of a substance which indicates that
the energy content of the substance can be lowered by the action
of biological agents (bacteria) through chemical reactions that
simplify the molecular structure of the substance.
Biological Oxidation: The process whereby, through the activity
of living organisms in an aerobic environment, organic matter is
converted to more biologically stable matter.
Biological Stabilization: Reduction in the net energy level of
organic matter as a result of the metabolic activity of organisms
so that further biodegradation is very slow.
Biological Treatment: Organic waste treatment in which bacteria
and/or biochemical action are intensified under controlled
conditions.
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Blinding: The plugging of the openings in the screen
fabric that is part of a process screening device.
or metal
Blowdown: A discharge of water from a system to prevent a
buildup of dissolved solids, e.g., in a boiler.
BOD5: A measure of the oxygen consumption by aerobic organisms
over a 5-day test period at 20°C. It is an indirect measure of
the concentration of biologically degradable material present in
organic wastes contained in a waste stream.
Casing: A tubular container made of natural or synthetic
material used to hold semiliquid sausage mixtures in a
cylindrical shape until cooked. Natural casings usually are
sheep intestines; synthetics are plastic materials.
Canned products: Any meat product from SIC code 2013 which
packaged for sale in a sealed can or similar container.
is
Category and Subcategory: Divisions of a particular industry
which possess different traits that affect raw waste water
quality.
Chemical Precipitation: A waste treatment process whereby
substances dissolved in the waste water stream are rendered
insoluble and form a solid phase that settles out or can be
removed by flotation techniques.
CIP System: "Clean-in-place" equipment and plant cleaning system
using a spray-on detergent that remains in place wherever it is
sprayed until it is rinsed off.
Clarification: Process of removing undissolved materials from a
liquid. Specifically, the removal of solids either by settling
or filtration.
Clarifier: A settling
from waste waters.
cm: Centimeter.
basin for separating settleable solids
Coagulant: A material, which, when added to liquid wastes or
water, creates a reaction which forms insoluble floe particles
that adsorb and precipitate colloidal and suspended solids. The
floe particles can be removed by sedimentation. Among the most
common chemical coagulants used in sewage treatment are ferric
sulfate and alum.
Coanda phenomenon:
curved surface.
Tendency of a flowing fluid to adhere to a
COD: Chemical oxygen demand; an indirect measure of the
biochemical load imposed on the oxygen resources of a body of
water when organic wastes are introduced into the water; a
chemical test is used to determine COD of waste water.
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Comminuted Products: Processed meat products prepared with meat
and fat pieces that have been reduced to minute particle size;
e.g., wieners, luncheon meats, bologna.
Contamination: A general term signifying the introduction into
water of microorganisms, chemical, organic, or inorganic wastes,
or sewage, which renders the water unfit for its intended use.
Cryogenic Liquid: A liquid that remains in the liquid state at
very low temperatures.
Curing: A process, method, or treatment involving aging,
seasoning, washing, drying, injecting, heating, smoking, or
otherwise treating a produce, especially meat, to preserve,
perfect, or ready it for use.
Denitrification: The process involving the facultative
conversion by anaerobic bacteria of nitrates into nitrogen and
nitrous oxides.
Digestion: Though "aerobic" digestion is used, the term
digestion commonly refers to the anaerobic breakdown of organic
matter in water solution or suspension into simpler or more
biologically stable compounds or both. Organic matter may be
decomposed to soluble organic acids or alcohols, and subsequently
converted to such gases as methane and carbon dioxide. Complete
destruction of organic solid materials by bacterial action alone
is never accomplished.
Dissolved Air Flotation: A process involving the compression of
air and liquid, mixing to supersaturation, and releasing the
pressure to generate large numbers of minute air bubbles. As the
bubbles rise to the surface of the water they carry with them
small particles that, they contact. The process is particularly
effective for grease removal.
Dissolved Oxygen: The oxygen dissolved in sewage, water, or
other liquid, usually expressed as milligrams per liter or as
percent of saturation.
Effluent:
unit.
Liquid which flows from a containing space or process
Emulsion: A system consisting of one component, such as fat,
thoroughly dispersed in an immiscible mixture in droplets or
globules so that the total system takes on a homogeneous
appearance.
Equalization Tank: A means of liquid storage capacity in a
continuous flow system, used to provide a uniform flow rate
downstream in spite of fluctuating incoming flow rates.
Eutrophication: Applies to a lake or pond, becoming rich in
dissolved nutrients, with seasonal oxygen deficiency.
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Evapotranspir ation: Loss of water from the soil, both by
evaporation and by transpiration from the plants growing thereon.
Extended Aeration: A form of the activated sludge process except
that the retention time of waste waters is one to three days.
Facultative Bacteria: Bacteria which can exist and reproduce
under e.'ther aerobic or anaerobic conditions.
Facultative Decomposition: Decomposition of organic matter by
facultative microorganisms.
Feed:
unit.
A material which flows into a containing space or process
Filtration: The process of passing a liquid through a porous
medium for the removal of suspended material by a physical
straining action.
Finger Dikes: Barriers or walls extending out into lagoons; in
waste treatment, to prevent or minimize the flow of incoming
water directly to the outlet and thereby short circuiting the
treatment process.
FP (Finished Product): The product of a plant in its final or
finished form and ready for packaging and shipment.
Floe: A mass formed by the aggregation of a
suspended particles.
number of fine
Flocculation: The process of forming larger flocculant masses
from a large number of finer suspended particles.
Floe Skimmings: The flocculant mass formed on a quieted liquid
surface and removed for use, treatment, or disposal.
Influent: A
process unit.
liquid which flows into a containing space or
Ion Exchange: A reversible chemical reaction between a solid and
a liquid by means of which ions may be interchanged between the
two. It is in common .use in water softening and water
deionizing.
Isoelectric Point: The value of the pH of a solution at which
the soluble protein becomes insoluble and precipitates out.
kg: kilograms or 1000 grams; a metric unit of weight.
kkg: 1000 kilograms.
Kjeldahl nitrogen: A measure of the total amount of nitrogen in
the ammonia and organic forms in waste water.
168
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KWH: Kilowatt*hours; a measure of total eleetri cal energy
consumption.
Lagoon: An all-inclusive term commonly given to a water
impoundment in which organic wastes are stored or stabilized or
both,
m: Meter; metric unit of length.
mm: Millimeter; 0.001 meters,
mg/1: Milligrams per liter; approximately equals parts per
million; a term used to indicate concentration of materials in
water. MGD or MGPD: Million gallons per day.
Microstrainer/Microscreen: A mechanical filter consisting of a
cylindrical surface of metal filter fabric with openings of 20-60
micrometers in size.
Municipal Treatment: A city- or community-owned waste treatment
plant for municipal and possibly industrial waste treatment.
New Source: Any building, structure, facility or installation
from which there is or may be a discharge of pollutants and whose
construction is commenced after the publication of the proposed
regulations.
Nitrate, Nitrite: Chemical compounds that include the NO3
(nitrate) and NO2 (nitrite) ions. They are composed of nitrogen
and oxygen in varying proportions. They are nutrients for growth
of algae and contribute to eutrophication.
Nitrification: The process of oxidizing ammonia by bacteria into
nitrites and nitrates.
No Discharge: No discharge of effluent to a water course. A
system of land disposal with no run-^off; or total recycle of the
waste water may be used to achieve no discharge.
Nonwater Quality: Noise, and all other environmental parameters
except water.
Off-gas: The gaseous products of a process that are collected
for use or more typically vented directly, or through a flare,
into the atmosphere.
Organic Content: Synonymous with volatile solids except for
small traces of some inorganic materials such as calcium
carbonate which will lose weight at temperatures used in
determining volatile solids.
Oxidation Lagoon: Synonymous with aerobic or aerated lagoon.
Oxidation Pond: Synonymous with aerobic lagoon.
169
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Percolation: The movement of water through the soil profile.
pH: A measure of the relative acidity or alkalinity of water. A
pH of 7.0 indicates a neutral condition. A greater pH indicates
alkalinity and a lower pH indicates acidity. A one unit change
in pH indicates a tenfold change in concentration of hydrogen
ion,
Pickle Solution: A water solution that may contain salt, sugar,
curing, or pickling agents, preservatives, and other chemicals.
It is used for injection or soaking of meat to prepare finished
meat products.
Point Source: Regarding waste water, a single plant with a waste
water stream discharging into a receiving body of water-
Pollutant: A substance which taints, fouls, or otherwise renders
impure or unclean the recipient system.
Pollution: The presence of pollutants in a system, sufficient to
degrade the quality of the system.
Polishing: Final treatment stage before discharge of effluent to
a water course. Carried out in a shallow, aerobic lagoon or
pond, mainly to remove fine suspended solids that settle very
slowly. Some aerobic microbiological activity also occurs.
Polyelectrolyte Chemicals: High molecular weight substances
which dissociate into ions when in solution; the ions either
being bound to the molecular structure or free to diffuse
throughout the solvent, depending on the sign of the ionic charge
and the type of electrolyte. They are often used as flocculating
agents in waste water treatment, particularly along with
dissolved air flotation.
Ponding: A waste treatment technique involving the actual holdup
of all waste waters in a confined space with evaporation and
percolation the primary mechanisms operating to dispose of the
water.
ppm: Parts per million; a
expressed currently as mg/1.
measure of concentration, usually
Pretreatment: Waste water treatment located on the plant site
and upstream from the discharge to a municipal treatment system.
Primary Waste Treatment; In-plant by-product recovery and waste
water treatment involving physical separation and recovery
devices such as catch basins, screens, and dissolved air
flotation*
Process Water: All waters that come into direct contact with the
raw materials, intermediate products, final products, by-
products, or contaminated waters and air. Raw Waste: The waste
water effluent from the in-plant primary waste treatment system.
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Recycle: The return of a quantity of effluent from a specific
unit or process to the feed stream of that same unit including
the return of treated plant waste water for general plant use.
Rendering: Separation of fats and water from tissue by
physical energy.
heat or
Return-on-Assets (ROA): A measure of potential or realized
profit as a percent of the total assets (or fixed assets) used to
generate the profit.
Return on Investment (ROI): A measure of potential or realized
profit as a percentage of the investment required to generate the
profit.
Reuse: Re, water reuse, the subsequent use of water following an
earlier use without restoring it to the original quality.
Riprap: A foundation or sustaining wall usually of stones and
brush, so placed on an embankment of a lagoon to prevent erosion.
Rotating Biological Contactor (RBC): A waste treatment device
involving closely spaced lightweight discs which are partly
immersed in and rotated through the waste water, allowing aerobic
microflora to accumulate on each disc and thereby achieve a
reduction in the waste content. Sand Filter: A filtering device
incorporating a bed of sand that, depending on design, can be
used in secondary or tertiary waste treatment.
Sedimentation Tank: A tank or basin in which a liquid (water,
sewage, liquid manure) containing settleable suspended solids is
retained for a sufficient time that part of the suspended solids
settle out by gravity. The time interval that the liquid is
retained in the tank is called "detention period". In sewage
treatment, the detention period is short enough to avoid
putrefaction.
Secondary Treatment: The waste treatment following primary, in-
plant treatment, typically involving biological waste reduction
systems. Settling Tank: Synonymous with "Sedimentation Tank".
Sewage: Water after it has been fouled by various uses. From
the standpoint of source it may be a combination of the liquid or
watercarried wastes from residences, business buildings, and
institutions, together with those from industrial and
agricultural establishments, and with such groundwater, surface
water, and storm water as may be present.
Shock Load: A quantity of waste water or pollutant that greatly
exceeds the normal discharged into a treatment system, usually
occurring over a limited period of time.
Sludge: The accumulated settled solids deposited from sewage or
other wastes, raw or treated, in tanks or basins, and containing
more or less water to form a semiliquid mass.
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Slurry: A solids-water mixture, with sufficient water content to
impart fluid handling characteristics to the mixture.
Stoichiometric Amount; The amount of a substance involved in a
specific chemical reaction, either as a reactant or as a reaction
product.
Suspended Solids (SS): Solids that either float on the surface
of, or are in syspension, in water, sewage, or other liquid
wastes, and which are largely removable by laboratory filtering
as in the analytical determination of SS content of waste water.
Surface Waters: The waters of the United States, including the
territorial seas.
Talmadge-Aiken Inspection; The sharing of meat and poultry
inspection responsibility and activity by state and federal
inspectors in certain states.
Temper: To soften or to allow the return to a previous condition
of temperature, moisture content, etc.
Tertiary Waste Treatment; Waste treatment systems used to treat
secondary treatment effluent and typically using physical-
chemical technologies to effect waste reductions. Synonymous
with "Advanced Waste Treatment."
Total Dissolved Solids (TDS); The solids content of waste water
that is soluble and is measured as total solids content minus the
suspended solids.
Zero Discharge: The discharge of no pollutants in the waste
water stream of a plant that is discharging into a receiving body
of water.
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TABLE 21
METRIC TABLE
CONVERSION TABLE
JLTIPLY (ENGLISH UNITS) by
ENGLISH UNIT ABBREVIATION CONVERSION
:re
re - feet
'itish Thermal
Unit
Iritish Thermal
Unit/ pound
[ubic feet/minute
lubic feet/second
ubic feet
ubic feet
ubic inches
egree Fahrenheit
eet
allon
[all on/minute
iorsepower
nches
nches of mercury
pounds
lillion gallons/ day
ile
i>0und/sguare
inch (gauge)
square feet
square inches
(short)
ac
ac ft
BTU
BTU/lb
cfm
cfs
cu ft
cu ft
cu In
°F
ft
gal
gpm
hp
in
in Hg
Ib
mgd
mi
psig
sq ft
sq in
ton
yd
Actual conversion, not a multiplier
0.405
1233.5
0.252
0.555
0.028
1.7
0.028
28.32
16.39
0.555(°F-32)*
0.3048
3.785
0.0631
0.7457
2.54
0.03342
0.454
3,785
1.609
(0.06805 psig +1)*
0.0929
6.452
0.907
0.9144
ha
cu m
kg cal
kg cal /kg
cu m/min
cu m/min
cu m
1
cu cm
°C
m
1
I/sec
kw
cm
atm
kg
cu m/day
km
atm
sq m
sq cm
kkg
m
TO OBTAIN (METRIC UNITS)
ABBREVIATION METRIC UNIT
hectares
cubic meters
kilogram - calories
kilogram calories/kilogram
cubic meters/minute
cubic meters/minute
cubic meters
1i ters
cubic centimeters
degree Centigrade
meters
liters
liters/second
killowatts
centimeters
atmospheres
kilograms
cubic meters/day
kilometer
atmospheres (absolute)
square meters
square centimeters
metric ton (1000 kilograms)
meter
173
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U.S. ENVIRONMENTAL PROTECTION AGENCY (A-107)
WASHINGTON, D.C. 20460
POSTAGE AND FEES PAID
ENVIRONMENTAL PROTECTION AGENCY
EPA-335
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