EPA 440/1-73/021
DEVELOPMENT DOCUMENT FOR
PROPOSED EFFLUENT LIMITATIONS GUIDELINES
AND NEW SOURCE PERFORMANCE STANDARDS
FOR THE
DAIRY PRODUCT PROCESSING
POINT SOURCE CATEGORY
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
JANUARY 1974
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Publication Notice
This is a development document for proposed effluent limitations
guidelines and new source performance standards. As such, this
report is subject to changes resulting from comments received
during the period of public comments of the proposed regulations
This document in its final form will be published at the time
the regulations for this industry are promulgated.
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DEVELOPMENT DOCUMENT
for
EFFLUENT LIMITATIONS GUIDELINES
and
NEW SOURCE PERFORMANCE STANDARDS
for the
DAIRY PRODUCTS PROCESSING
POINT SOURCE CATEGORY
Russell E. Train
Administrator
Robert L. Sansom
Assistant Administrator for Air & Water Programs
Allen Cywin
Director, Effluent Guidelines Division
Richard Gregg
Project Officer
January, 1974
Effluent Guidelines Division
Office of Air and Water Programs
United States Environmental Protection. Agency
Washington, D.C. 20460
U.S. Environmental Protection Agency
fogion 5,Ubrary(Pi-i2J)
W West Jackson Boulevard, 12th Ftoar
Chicago. II 60604-3590
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i~"V1^7TT' f
il\ v iiv,
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TABLE OF CONTENTS
Section Page
I Conclusions 1
Size and Nature of the Industry 1
Industry Categorization 1
Pollutants and Contaminants 2
Control and Treatment of Waste Water 2
II Recommendations 3
BOD_5 3
Suspended Solids 4
pH 4
Method of Application 4
Multi-product Plants 5
Time Factor for Enforcement of the Guidelines . 5
III Introduction 7
Purpose and Authority 7
Summary of Methods 8
Basic Sources of Waste Load Data 9
General Description of the Industry 11
IV Industry Categorization 33
Introduction 33
Raw Materials Input 33
Processes Employed 33
Wastes Discharge 34
Finished Products Manufactured 34
Conclusion 35
V Waste Characterization 37
Sources of Waste 37
Nature of Dairy Plant Wastes 38
Variability of Dairy Wastes 41
Waste Load Units 41
BOD 45
COD 45
Suspended Solids 47
pH 50
Temperature 50
Phosphorus 50
Nitrogen 51
Chloride 51
Waste Water Volume 51
Polluting Effects 54
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TABLE OF CONTENTS (Cont'd)
Section
VI
VII
VIII
Pollutant Parameters 55
BODj[ 55
COD 55
Suspended Solids 56
pH 57
Temperature 57
Phosphorus 59
Nitrogen 59
Chloride 59
Control and Treatment Technology 61
In-Plant Control Concepts 61
Plant Management Improvement 61
Waste Monitoring 62
Engineering Improvements for In-Plant Waste
Control 63
Waste Management Through Equipment Improvements 63
Waste Management Through Systems Improvements 66
Waste^Management Through Proper Plant Layout
and Equipment Selection 68
Waste Reduction Possible Through Improvement
of Plant Management and Plant Engineering . 70
End-of-Pipe Waste Treatment Technology .... 79
Design Characteristics 82
Problems, Limitations and Reliability .... 85
Treatment of Whey 85
Advantages and Disadvantages of Various Systems 90
Management of Dairy Waste Treatment System . . 90
Tertiary Treatment 95
Pretreatment of Dairy Waste Discharged to
Municipal Sanitary Sewers 99
Performance of Dairy Waste Treatment Systems . 100
Cost, Energy and Non-Water Quality Aspects .... 107
Cost of In-plant Central 107
Cost of End-of-Pipe Treatment 112
Cost and Reduction Benefits of Alternative
End-of-Pipe Treatment Technologies 121
Non-Water Quality Aspects of Dairy Waste
Treatment 122
Energy Requirements 126
vi
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TABLE OF CONTENTS (Cont'd)
Section Page
IX Effluent Reduction Attainable Through the
Application of the Best Practicable Control
Technology Currently Available 127
Introduction 127
Effluent Reduction Attainable Through the
Application of the Rest Practicable Control
Technology Currently Available 128
Identification of Best Practicable Control
Technology 130
Rationale for Selection of Best Practicable
Control Technology Currently Available . . . 130
X Effluent Reduction Attainable Through the Application
of the Best Available Control Technology Economically
Achievable 133
Introduction 133
Effluent Reduction Attainable Through the
Application of the Best Available Control
Technology Economically Achievable 134
Identification of Best Available Control
Technology Economically Achievable 136
Rational for Selection of Best Available Control
Technology Economically Achievable 137
XI New Source Performance Standards 139
Introduction 139
Effluent Reduction Attainable in New Sources . 140
XII Acknowledgements 141
XIII References 143
XIV Glossary 155
vii
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TABLES
Number
1 Effluent Limitation Guidelines for BCD 3
2 Standard Industrial Classification of the Dairy
Industry 12
3 Utilization of Milk by Processing Plants 15
4 Number of Dairy Plants and Average Production 16
5 Production of Major Dairy Products, 1963 and 1970 16
6 Employment in the Dairy Industry 17
7 Proposed Subcategorization for the Dairy Products Industry. 36
8 Cornposition of Camion Dairy Products Processing Materials . 39
9 Estimated Contribution of Wasted Materials to the BOD5_ Load
of Dairy Waste Water. (Fluid Milk Plant) 40
10 Summary of Calculated, Literature Reported and Identified
Plant Raw Waste BOD5_ Data 46
11 Sunmary of Literature Reported and Identified Plant Source
BOD5_:COD Ratios for Raw Dairy Effluents 48
12 Summary of Identified Plant Source Raw Suspended Solids
Data 49
13 Summary of Literature Reported and Identified Plant Source
Raw Waste Water Volume Data 52
13A Summary of Literature Reported and Identified Plant Source
Raw Waste Water Volume Data (FPS Units) 53
14 Summary of pH, Temperature, and Concentrations of Nitrogen,
Phosphorus, and Chloride Ions — Literature Reported
and Identified Plant Sources 58
15 Effect of Engineering Improvement of Equipment, Processes
and Systems on Waste Reduction 75
16 Recamended Design Parameters for Biological Treatment
of Dairy Wastes 83
17 Advantages and Disadvantages of Treatment Systems Utilized
in the Dairy Industry 91
18 Typical BCD and Suspended Solids Concentrations of
Dairy Effluents 96
19 Effect of Milk Lipids on the Efficiency of Biological
Oxidation of Milk Wastes 101
20 Performance of Dairy Wastes Water Treatment Plants . . . .103
21 General Comparison of Tertiary Treatment Systems Efficiency 104
22 Plant Performance Data for the Tertiary Treatment Plant at
South Tahoe, California 105
23 Estimated Cost of Engineering Improvements of Equipment
and Systems to Reduce Waste 108
24 Tertiary Treatment Systems Cost 120
25 Biological System Cost Comparisions as Applied in the
Chemical Industry 121
26 Incremental BCD5_ Removal and Cost Efficiency of Secondary,
Tertiary, and Recycle Treatment Systems - 50,000 Pounds
Per Day Milk Equivalent Processed 123
ix
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27 Incremental BOD5_ Removal and Cost Efficiency of Secondary,
Tertiary, and Recycle Treatment Systems - 250,000 Pounds
Per Day Milk Equivalent Processed 124
28 Incremental BCD5_ Removal and Cost Efficiency of Secondary,
Tertiary, and Recycle Treatment Systems - 750,000 Pounds
Per Day Milk Equivalent Processed 125
29 BOD5_ Reduction Attainable Through the Application of Best
Practicable Control Technology Currently Available ... 129
30 BCD5_ Reduction Attainable Through the Application of Best
Available Control Technology Economically Achievable . . 135
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FIGURES
Number
1 Receiving Station - Basic Process 21
2 Fluid Milk - Basic Process 22
3 Cultured Products - Basic Process 23
4 Butter - Basic Process 24
5 Natural and Processed Cheese - Basic Process 25
6 Cottage Cheese - Basic Process 26
7 Ice Cream - Basic Process 27
8 Condensed Milk - Basic Process 28
9 Dry Milk - Basic Process 29
10 Condensed Whey - Basic Process 30
11 Dry Whey - Basic Process 31
12 Hourly Variations in ppm BCD5_, COD and
Waste Water for a Dairy Plant 42
13 Variation in Waste Strentgh of Frozen Products Drain for
Consecutive Sampling Days in One Month 43
14 Waste Coefficients for a Fluid Milk Operation Normal
Operation (#BCD/1000# Milk Processed, Gal. Waste
Water/1000# Milk Processed 73
15 Waste Coefficients After Installation of Engineering Advances
in a Fluid Milk Operation (#BCD/1000# Milk Processed, Gal.
Waste Water/1000# Milk Processed) 74
16 Fat Losses as a Function of Time During Start-up and
Shut-down of a 60,000 Pound/Hour HTST Pasteurizer .... 80
17 Recommended Treatment Systems for Dairy Waste Water .... 83
18 Tertiary Treatment of Secondary Effluent for Complete
Recycle 98
19 Capital Cost (August, 1971) Activated Sludge Systems
(For Dairy Wastewater) 113
20 Capital Cost (August, 1971) Trickling Filter Systems
(For Dairy Wastewater) 114
21 Capital Cost (August, 1971) Aerated lagoon (For
Dairy Wastewater) 115
22 Operating Costs (August, 1971) Activated Sludge System,
Trickling Filter System, and Aerated Lagoon (For
Dairy Wastewater) 116
23 Operating Costs (August, 1971) Activated Sludge, Trickling
Filter and Aerated Lagoon Systems (For Dairy
Wastewater) 117
xi
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SECTION I
CONCLUSIONS
Size and Nature of the Industry
The basic function of the dairy products processing industry is the
manufacture of foods based on milk or milk products. However, a limited
number of nonmilk products such as fruit juices are processed in some
plants.
There are over 5,000 plants in the dairy products industry located all
over the United states. Plants range in size from a few thousand kilo-
grams to over 1 million kilograms of milk received per day.
There are about 20 different basic types of products manufactured by the
industry. A substantial number of plants in the industry engage in
multi-product manufacturing, and product mix varies broadly among such
plants.
For the purpose of establishing effluent limitations guidelines and
standards of performance the dairy products industry can be logically
subcategorized in relation to type of product manufactured. Available
inf ormaticn permits a meaningful segmentation into the following sub-
categories at this time:
Receiving stations
Fluid products
Cultured products
Butter
Cottage cheese
Natural cheese
Ice cream
Ice cream mix
Condensed milk
Dry milk
Condensed whey
Dry whey
Factors such as size and age of plants, minor variations in processes
employed, and geographical location generally do not have an effect on
plant waste loads that would justify additional subcategorization.
However, a measurable distinction between receiving stations that
receive milk in cans and those that receive milk in bulk can be made at
this time. Similar distinction can be made for natural cheese plants
receiving less than 75,000 Ib milk/day and those receiving over 75,000
Ib milk/day. This is reflected in the recommended guidelines.
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The most significant pollutants contained in dairy products plant wastes
are organic materials which exert a biochemical oxygen demand and
suspended solids. Raw waste waters from all plants in the industry
contain quantities of these pollutants that are excessive for direct
discharge without appreciable reduction. The pH of many individual
waste streams within a plant are outside the acceptable range, but there
is generally a tendency for neutralization with co-mingling of waste
streams. However, adjustment of pH is easily accomplished and the final
discharge (s) from a plant should be kept within an acceptable range.
Additional contaminants found in dairy plant wastes include:
phosphorus, nitrogen, chlorides, and heat. In general, control and
treatment of the primary pollutants (organics and suspended solids) will
hold these lesser pollutants to satisfactory levels. In isolated cases
where these pollutants may be critical they should be handled on a case
by case basis.
A major contributor to dairy waste BOD5 is dairy fat, which is being
treated successfully biologically. This is in contrast to mineral based
oil which inhibits the respiration of microorganisms. The standard
hexane soluble FOG (fats, oils, and grease) test used presently does not
differentiate between mineral oil and dairy fat. Separate standards and
tests should be developed for these two parameters.
Cgntrol_and_Treatment_gf_Waste_Water
In-plant controls, including management and engineering improvements,
that are readily available and economically achievable can substantially
reduce waste loads in the dairy industry. In many cases these controls
can produce a net economic return through by-product recovery or reduced
cost of waste treatment.
Conventional end-of-pipe treatment technology is capable of achieving a
high degree of reduction when applied to the raw wastes of dairy plants.
Attainment of zero discharge by complete recycle of waste waters,
through a technical possibility through employment of reverse osmosis,
carbon filtration and other advanced treatment technique, is beyond the
realm of economic feasibility for most if not all plants in the
industry.
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SECTION II
RECOMMENDATIONS
It is recommended that effluent limitation guidelines and standards of
performance for new sources in the dairy products industry be
established for BOD5 suspended solids, and pH. These standards are
recommended cnly for dairy plants discharging to navigable waters. For
dairies discharging to sanitary systems, municipalities should adopt
other standards that reflect their own particular requirements
EOD5
Recommended effluent limitations guidelines and standards of performance
for BODS are set forth in Table 1.
Table 1
Effluent Limitation Guidelines for BOD
Effluent Limitations Guidelines
Subcategory (1)
Receiving Station
Cans
Bulk
Fluid Products
Cultured Products
Butter
Cottage Cheese
Natural Cheese
Ice Cream
Ice Cream Mix
Condensed Milk
Dry Milk
Condensed Whey
Ery Whey
Level_I (3)
(4) Leyel_III (5)
Notes:
(1)
(2)
(3)
(4)
(5)
(6)
020
012
060
080
081
U56
,028
240
060
040
060
040
0.060
0,
0.
0.
0,
0,
0.
0,
0,
0.
0.
0,
0.
0.
006
003
008
011
013
107
006
035
008
008
011
008
011
,006
,003
,008
011
013
,107
,006
,035
008
008
,011
008
0.011
See Table II for definition of products included in
each subcategory.
See calculation of BOD5 below for derivation of
values for BOD5 received.
Best practicable control technology currently available.
Best available technology economically achievable.
Standards of performance for new sources.
Table I standards for BPCTCA generally reflect
average raw waste loads with a 96% BOD5 reduction applied.
For BATEA and SPNS standards, a 98% BOD5
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reduction was applied to lower raw waste values.
Although conventional treatment units are
available to reduce raw waste BOD^ concentrations
by 96%, the recommended EPCTCA standards can also
be achieved by further in-plant BOD5 reduction
followed by a treatment system performing less
than 96% BOD5 reduction. The same case applies to
BATEA and SPNS.
Suspended^Solidg
Recommended effluent limitations guidelines and standards of performance
for suspended solids are, for corresponding subcategories and levels of
technology, numerically the same as for BOD5 but expressed in kilograms
suspended solids per 100 kilograms BOD^ received.
It is recommended that the pH of any final discharge { s) be within the
range of 6.0-9.0.
Methgd_gf^_A]3£licatign
Calculation of BODS Received.
It is recommended that in applying the guidelines and standards the
waste load of a particular plant be determined and compared to the
guidelines and standards. In doing so, it is imperative that
consistency be maintained in regard to the basis on which the waste
loads are developed.
To maintain consistency the calculation of the BOD5 received (going into
processes in the case of multi-product plants) must be done on the fol-
lowing basis:
1. All dairy raw materials (milk and/or milk products) and
other materials (e.g. sugar) must be considered.
2. The EOD5 input must be computed by applying factors of 1.031,
0.890 and 0.691 to inputs of proteins, fats and carbohydrates
respectively. Organic acids (such as lactic acid) when
present in appreciable quantities should be assigned the
same factor as carbohydrates. The composition of raw
materials may be obtained from the U.S. Department of
Agriculture Handbook No. 8, Composition of Foods and
ether reliable sources. Compositions of some common
raw materials are given in Table 8.
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Multi-Product_Plants
The guidelines and standards set forth in Table 1 apply only to single-
product plants. It is recommended that limitations for any multi-
product plant be derived from Table 1 on the basis of a weighted
average, i.e. , weighting the single-product guideline by the BODj>
processed in the manufacturing line fcr each product. That is:
Multi-product Limitation =
Single Product Guideline x _BOD5_processed Ikg^or^lb.^
(kg/100 kg or lb/100 Ib) ~ 100
Time Factor for
Enfgrcement_of__the_Guidelines
The proposed effluent limitations and performance standards are based on
thirty-day averages. For purposes of enforcement and determination of
violations, daily maximums of three to five times the thirty-day average
should apply.
Because of the wide hourly and daily fluctuations of waste
concentrations and waste water flows in the dairy products industry,
waste loads should be measured on the basis of daily proportional
composite sampling.
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SECTION III
INTRODUCTION
Section 301 (b) of the Act requires the achievement 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 economically achievable including treatment techniques,
process 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
dairy products processing industry.
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 (1) (A) of the Act to propose regulations establishing
Federal standards of performances 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 within the dairy industry which was included
within the list published January 16, 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 dairy
products processing industry was first analyzed for the purpose of
determining whether separate limitations and standards are appropriate
for different segments within the industry. Such analysis was based
upon raw material used, product produced, manufacturing process
employed, and other factors. The raw waste characteristics for each
subcategory were then identified. This included an analyses of (1) the
source and volume of water used in the process employed and the sources
of waste and waste waters in the plant; and (2) the constituents
(including thermal) of all waste waters including toxic constituents and
other constituents which result in taste, odor, and color in water or
aquatic organisms. The constituents of waste waters which should be
subject to effluent limitations guidelines and standards of performance
were identified.
The full range of control and treatment technologies existing within
each subcategory was identified. This included an identifaciton of each
distinct control and treatment technology, including both in-plant and
end-of-prccess technolgies, which are existent or capable of being
designed for each subcategory. It also included an identification in
terms of the amount of constituents (including thermal) and the
chemical, physical, and biological characteristics of pollutants, of the
effluent level resulting from the application of each of the treatment
and control technologies. The problems, limitations and reliability of
each treatment and control technology and the required implementation
time were also identified. In addition, the non-water quality
environmental impact, such as the effects of the application of such
technologies upon other technology and the required implementation time
were also identified. in addition, the non-water quality environmental
impact, such as the effects of the application of such technologies upon
other pollution problems, including air, solid waste, noise and
radiation were also idenitified. The energy requirements of each of the
control and treatment technologies were identified as well as the cost
of the application of such technologies.
The information, as outline above, was then evaluated in order to
determine what levels of technology constituted the "best practicable
control technology currently available," "best available technology,
processed, 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 process employed, the engineering
aspects of the application of various types of control techniques,
process changes, non-water quality environmental impact (including
energy requirements) and other factors.
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The data for identification and analyses were derived from a number of
sources. These sources included EPA research information, published
literature, a voluntary questionaire issued by the Dairy Industry
Committee, qualified technical consultation, and on-site waste sampling,
visits, and interviews at dairy food processing plants throughout the
United States. All references used in developing the guidelines for
effluent limitations and standards of performance for new sources
reported herein are included in Section XIV of this document.
Basic_Sources_of_Waste_Load_Data_
Prior Research
At the outset of this study, it was recognized that most of the
information en dairy food plant wastes available as of 1971 had been
collected and reviewed in two studies prepared for EPA:
1. "Study of Wastes and Effluent Requirements of the Dairy Industry,"
July 1971, by A.T. Kearney, Inc., for the Water Quality Office, EPA.
2. "Dairy Food Plant Wastes and Waste Treatment Practices, "March
1971, by Department of Dairy Technology, The Ohio State University, for
the Office of Research and Monitoring, EPA.
The purpose of the 1971 Kearney study was to establish an informational
background and recommend preliminary effluent limitation guidelines for
the dairy industry. The Ohio State University study was a "state-of-
the-art" report that set forth in great detail practically all available
technical knowledge on dairy products processing. Dr. W. James Harper,
the lead investigator for the Ohio State University study, served as a
consultant to A. T. Kearny for the preparation of its report for the
Water Quality Office, and essentially the same data base was utilized in
both studies.
Sources of Data For This Study
Although many of the key factors affecting waste loads had been
identified in the aforementioned reports and other technical literature,
it was recognized that an expanded and refined data and informational
base was needed to meet requirements associated with development of
effluent limitations guidelines for the dairy products industry.
Furthermore, it is imperative that all data used for development of
guidelines be of a "verifiable" nature (i.e., the result of testing in
identified plants that could be available for verification of data if
necessary), and much of the data in the technical literature is not
identified as to specific source. A concerted effort was devoted to a
program to develop new and verifiable data that would supplement or even
supplant the data available in the technical literature.
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The body cf quantitative data on wastes available for development of
effluent limitations guidelines that resulted from this program was an
aggregate cf portions obtained from the following sources;
1. In-plant sampling of waste streams at selected dairy plants
undertaken by independent certified laboratories under the direction of
A.T. Kearney and with the assistance of dairy plant managements.
2. In-plant sampling at selected plants performed by the dairy
companies utilizing contractors or company technical personnel, and with
quality control assured by direction and observation of A.T. Kearney or
EPA.
3. Data obtained from State and Municipal agencies (e.g., the
Metropolitan Sanitary District of Greater Chicago) which have monitored
the waste of selected dairy plants for regulatory purposes.
4. Eata supplied by dairy companies which are the result of
sampling programs conducted by the companies since the time of Kearney's
1971 study.
5. Plant waste survey data developed by independent research
organizations (e.g.. North Carolina Sate University) at selected dairy
operations in the last two years.
6. Eata furnished by the dairy industry to Kearney and Ohio Stae
University during the 1971 studies for EPA in coded Form, but through
company cooperation now identified as to specific plant source with
pertinent operational parameters furnished.
Quality of the Data
Because of the high variability of dairy plant wastes in hydraulic load
and strength, both during a day and from day to day, it is recognized
that a composite made up of samples taken at hourly intervals or over a
few days may yield values that depart considerably from true average
loads. However, the variance that may exist because of low frequency of
sampling or insufficient number of days in the sampling period decreases
at the number of data points (one-day composites) in the data base
increases.
While the approximately 150 plants included in the verifiable data base
constitute only 3% of the total number of plants within the dairy
products industry, it should be noted that the data base is the most
extensive one of its nature compiled to date. The numb€>r of individual
product manufacturing lines represented in aggregate is much greater
than the number of plants, since many of the facilities are multi-
product plants. Moreover, two additional factors should be borne in
mind. The major thrusts in developing the data base were directed
toward obtaining information on exemplary operations and securing
representation of the range of size, age and other variables encountered
in plants manufacturing each type of finished product.
10
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Several control measures were imposed on -the sampling program to
maintain the quality of the waste load data. All analyses employed
approved standard methods conducted under acceptable laboratory quality
control. Flow-weighted composite sampling was used in all but a few
cases, with the time interval between taking all aliquots ranging from 2
to 60 minutes. Exceptions were made only when information from a
particular plant was highly desirable and installation of flow-
proportioned composite sampling equipment was not possible. Constant
volume sampling at set intervals was accepted in some cases when there
was indication that variation of flow was within the limits of error of
many field-flew measurement devices.
The number of days in any one sampling period at a plant ranged from 1
to 10 days, with the vast majority of the cases entailing 3 or more
days. In a number of cases the data on plants that was furnished by
the companies covered a long-term monitoring program.
General Description of the Industry
Production Classification
The industrial category covered by this document comprises all
manufacturing establishments included in Standard Industrial
Classification (SIC) Group No. 202 ("Dairy Products"), and "milk
receiving stations primarily engaged in the assembly and reshipment of
bulk milk for the use of manufacturing or processing plants" (included
in SIC Industry No. 5043).
The common characteristic of all plants covered by this definition is
that milk or milk by-products, including whey and buttermilk, are the
sole or principal raw materiasl employed in the production processes. A
comprehensive list of the types of products manufactured by the
industry, as classified by the Office of Statistical Standards, appear
in Table 2.
In recent years, many establishments classified within the dairy
industry have also engaged in manufacturing other than products based on
milk or irilk by-products. Such is the case of fluid milk plants in
which filling lines are also utilized for processing fruit juices, fruit
drinks and other flavored beverages. The guidelines developed in this
study are not intended to cover processes where other than milk-based
products are involved.
Effluent limitations for those cases involving non-dairy products are
more logically handled by application of guidelines developed for
appropriate industries (e.g., beverages or fruits) or on an individual
basis with consideration given to the BOD5 of the raw materials and the
11
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TAELE_2
STANDARD INDUSTRIAL CLASSIFICATION
Q£_THE_DAIRY_INDUSTRY
(AS EEFINED BY THE OFFICE OF STATISTICAL STANDARDS)
Group Industry
202 PAIRY_PROEyCTS
This group includes establishments primarily
engaged in; (1) manufacturing creamery
butter;natural cheese; condensed and
evaporated milk; ice cream and frozen
desserts; and special dairy products, such
as processed cheese and malted milk: and
(2) processing (pasteurizing homogenizing,
vitaminizing, bottling fluid milk and cream
retail for wholesale or retail distribution.
Independently operated milk receiving
stations primarily engaged in the
assembly and reshipment of bulk milk for
the use of manufacturing or processing
plants are included in Industry 5043.*
2021 Cr eame ry__ Eutte r
Establishments primarily engaged in
manufacturing creamery butter.
Anhydrous milkfat
Butter, creamery and whey
202 2022 _Cheesex_Natural_and_Processed
Establishments primarily engaged in
manufacturing all types of natural
cheese (except cottage cheese—
Industry 2026), processed cheese,
cheese foods, and cheese spreads.
Cheese, all types and varieties
except cottage cheese
Cheese, natural
Cheese, processed
Cheese spreads, pastes, and
cheeselike preparations
Processed cheese
12
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Sandwich spreads
2023 Cgndensedjand_EvaEprated Milk
Establishments primarily engaged in
manufacturing condensed and evaporated
milk and related products, including ice
cream mix and ice milk mix made for sale
as such and dry milk products.
Baby formula, fresh, processed and
bottled
Buttermilk; concentrated, condensed,
dried, evaporated, and powdered
Casein, dry and wet
Cream; dried, powdered, and canned
Dry milk products; whole milk;
nonfat miIk;buttermilk; whey and
cream
Ice milk mix, unfroze; made in
condensed and evaporated milk
plants
Lactose, edible
Malted milk
Milk; concentrated, condensed,
dried evaporated and powdered
Milk, whole; canned
Skim milk: concentrated, dried,
and powdered
Sugar of milk
Whey: concentrated, condensed,
dried evaporated, and powdered
202 2024 lce_Cream_and_Frozen_r Desserts
Establishments primarily engaged in
manufacturing ice cream and other
frozen desserts.
Custard, frozen
Ice cream: bulk, packaged, molded,
on sticks, etc.
Ice milk: bulk, packaged, molded,
on sticks, etc.
Ices and sherberts
Mellorine
Mellorine-type products
Parfait
13
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Sherberts and ices
Spumoni
2026 Fluid Milk
Establishments primarily engaged in
processing (pasteurizing, homgenizing
vitaminizing bottling) and distributing
fluid milk and cream, and related products.
Buttermilk, cultured
Cheese, cottage
Chocolate milk
Cottage cheese, including pot,
bakers', and farmers' cheese
Cream, aerated
Cream, bottled
Cream, plastic
Cream, sour
Kumyss
Milk, acidophilus
Milk, bottled
Milk processing (pasteurizing,
homogenizing, vitaminizing,
bottling) and distribution:
with or without manufacture of
dairy products
Milk products, made from fresh
milk
Route salemen for dairies
Whipped cream
Yoghurt
Zoolak
14
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less of materials that is consistent with levels of treatment and
control established for the dairy products industry.
Number of Plants and Volume Processed
In 1970, there existed approximately 5,350 diary plants in the United
States, which processed about 51 billion kg of milk, or 96% of the milk
produced at the farm. The utilization of milk to manufacture major
types cf products was as given in Table 3.
TABIE_3
Utilization of Milk by Processing Plants (1970)
Percent of
Use Total Milk Produced
Fluid Products 15.1
Butter 22.2
Natural Cheese 17.0
Ice Cream and other Frozen Products 11.4
Evaporated Milk 2,8
Cottage Cheese 1.0
Cry Milk t5
100.0
The dairy industry comprises plants that receive anywhere from a few
thousand to over 1 million kg of milk and milk by-products per day. The
plants are located throught the country, with regional concentrations in
Minnesota, Wisconsin, New York, Iowa and California.
Trends
Significant trends in the U.S. dairy industry which bear on the waste
disposal problem include: (a) a marked decrease in the number of plants
and increased production per plant (b) changes in the relative
production of variouse types of dairy foods, (c) increasing automation
of processing and handling facilities, and (d) changes in location of
the plants.
Plants and Production
Over the past 25 years, dairy food processing plants in the United
States have been decreasing in number and increasing in size. The main
reasons for this trend are economic and technolgical including unit cost
reductions attainable by processing larger volumes, and improvements in
transportation,storage facilities and product shelf-life, which allow
the products to be handled over longer distances and longer periods.
15
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The change in number of plants and processsing capacity in the past
decade is reflected in Table 4 below.
TABLE_4
Number of Dairy Plants and Average Production
Average Annual Production
Per Plant
Millign_kg __ (Ib) ___ of Product
1970 1963 1970
Fluid Products 8 4,619 2,824 5.6 (12.3) 9.7 (21.3)
Cottage Cheese
Putter 1,320 619 0.5 (1.1) 0.7 (1.5)
Cheese 1,283 963 0.5 (1.1) 1.0 (2.2)
Evaporated 8
Cry irilk 281 257 18.0 (39.6)19.1 (42.0
Ice Cream 8
Frozen Dessert 1^.081 68J 3...0 _(6._6l_ 6^7 JliUll
8,584 5,352
Table 5 reflects the trends in production of dairy products. While
production of butter and condensed products has been on the decline, the
production of natural cheese, cottage cheese, ice cream, and fluid
products has been increasing:
TAELE_5
Production of Major Dairy Products, 1963 and 1970
Total Production
Type of Product Mil.ligr^s_of _Kd.logramsJPoui^dsj_
Percent
II6. 3 _ 1^70 Change
Butter 636 (1,399) 500 (1,050) -21%
Condensed and Dry Products 5,050 (11,110) 4,910 (10,802) -3%
Cheese 730 ( 1,606) 1,000 ( 2,200) 37%
ice Cream 8 Frozen Desserts 4,050 ( 8,910) 4,590 (10,098) 13%
Cottage Cheese 410 ( 902) 450 ( 990) 11%
Fluid Products 25^550 (56,110) 27X050 (59,510) 6%
36,416 36,500
It is important to note that those sectors of the dairy products
industry that are experiencing the highest rates of growth (ice cream,
16
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frozen deserts, and cottage cheese) are also those which have been shown
to produce proportionally the largest waste.
Because it is produced in such large volumes and is relatively low in
solids content, whey has long posed a utilization problem for the
industry. The problem has increased as plants have become larger and
more distant from farming areas where whey can be used directly as feed.
Cottage cheese whey represents the more serious problem because its acid
nature limits its utilization as feed or food.
It is estimated that between 30% to 50% of the whey produced is
currently discarded as waste, seme of which goes to municipal treatment
plants. Because of its microbial inhibiting effect, unless whey is
diluted with other wastes, it can potentially shock the receiving
treatment system.
Plant Automation
As plants have increased in size there has been a tendency to mechanize
and automate irany processing and handling operations. This is reflected
by the decreasing employment in the industry as shown in Table 6..
TABLE_6_
Employment in the Dairy Industry
Employment
(Thousands) per million kkg.
Ty_p)e_of_Plant Tot a 1_ Employment P£2^u£§d_ Annually
1963 J.970 1963 1970
Butter 12.0 7.2 18.7 14.3
Cheese 17.9 21.1 24.6 20.9
Condensed & Dry
Products 12.2 10.7 2.4 2.2
Ice Cream 8 Frozen
Desserts 29.1 22.4 7.3 4.8
Fluid Products &
Cottage cheese 185.0 140.7 7.0 5.1
The principal technoligical developments that are being widely applied
throughout the industry and which have significance in relation to waste
loads include:
1. Receiving milk in tank trucks, with automated rinsing and cleaning
of the tanks at the plant.
2. Remote-controlled, continous-flow processing of milk at rates up to
45,000 kilograms per hours, with automatic standardizing of fat content.
17
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3. Use of cleaned-in-place (CIP) systems that do not require daily
dismantling of the equipment and utilize contolled amounts of detergents
and sanitizing chemicals.
4. High speed, automatic filling and packaging operations
5. Automated materials handling by means of conveyors, casers and
stackers
Although automation can theoretically provide for lower waste loads
through in-plant waste control engineering, at the present time other
factors have greater influence in the waste loads, as discussed later in
this report.
Plant Location
As dairy plants have increased in size, the trend has been to receive
milk from and distribute products to larger areas. As a result, the
location cf a plant has becoire independent of the immediate market
place. Quite often, the prevailing factor has been to select a site
with covenient access to major highway system covering the area
serviced, usually at some distance from the larger urban centers.
The problem of waste disposal has frequently been given little attention
in selecting the location of large new plants. A number of facilities
with waste loads up to 3,500 kg BOD5/day have been constructed in
suburban areas of cities of under 50,000 population. Where such plants
utilize the municipal sewage treatment facility they may become the
largest contributor to the municipal system, imposing on it the problems
that are typically associated with dairy wastes, such as highly variable
hydraulic and BOD5 loads and the risk of shock-leads when whey is
discharged without equalization.
Processing Operations
A great variety of operations are encountered in the dairy products
industry, but in oversimplication they can be considered a chain of
operations involving receiving and storing of raw materials, processing
of raw materials into finished products, packaging and storing of
finished product, and a group of ancillary operations (e.g., heat
transfer and cleaning) only indirectly involved in processing of
materials.
Facilities for receiving and storing raw materials are fairly consistent
throughout the industry with few if any major modifications associated
with changes of raw materials. Basically they consist of a receiving
area where bulk carriers can be attached to flexible lines or cans
dumped intc hoppers, fixed lines and pumps for transfer of materials,
and large refrigerated tanks for storage. Wastes arise from leaks,
18
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spills and removal of adhering materials during cleaning and sanitizing
of equipment. Under normal operations, and with good housekeeping,
receiving and storing raw materials is not a major source of waste lead.
It is in the area of processing raw materials into finished products
that the greatest variety is found, since processes and equipment
utilized are determined by raw material inputs and the finished products
manufactured. However, the initial operations of clarification,
separation and pasteurization are common tc most plants and products.
Clarification (removal of suspended matter) and separation (removal of
cream, or for whole milk standrdization to 3.5% butterfat content)
generally are accomplished by using large centrifuges of special design.
In some older installations clarification and separation are carried out
in separate units that must be disassembled for cleaning and sanitizing,
and for sludge removal in the case of clarification. In most plants
clarification and separation are accomplished by a single unit that
automatically discharges the sludge and can be cleaned and sanitized
without disassembly (cleaned in place or CIP).
Following clarification and separation, those materials to be subjected
tc further processing within the plant are pasteurized. Pasteurization
is accomplished in a few elder plants by heating the material for a
fairly long period of time in a vat (vat pasteurization). In most
plants pasteurization is accomplished by passing the material through a
unit where it is first rapidly heated and then rapidly cooled by contact
with heated and cooled plates or tubes (high temperature short time or
HTST pasteurization).
After the initial operations mentioned above, the processes and
equipment employed become highly dependent on product. Examples of
equipment encountered are; tanks and vats for mixing ingredients and
culturing products, homogenizers (enclosed high-pressure spray units),
evaporators and various driers for removal of water, churns and
freezers. The processes employed for manufacture of various products
are indicated in Figure 1 through 11. The Finished products are then
packaged, cased and sent to storage for subsequent shipment.
The product fill lines employed in the dairy products industry are
typical liquids and solids packing units, much like those employed in
many industries, with only minor modifications to adapt them to the
products and containers of the industry. Storage is in refrigerated
rooms with a range of temperaturs from below zero to above freezing.
The product manfacture and packaging areas of a plant are the major
sources of wastes. These wastes result from spills and leaks, wasting
of by-products (e.g., whey from cheese making), purging of lines during
product change in such as freezers and fillers, product washing (e.g.,
curd washing for cheese) and removal of adhering materials during
cleaning and sanitizing of equipment. Wastes from storage and shipping
19
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result frcir rupture of containers due to mishandling and should be
irinimal.
It should be noted that most plants are multi-product facilities, and
thus the process chain for a product may differ from the single product
chain indicated in Figures 1 through 11. Frequently in multi-product
plants a single unit such as a pasteurizer may be utilized for
processing more than one product. This represents considerable savings
in capital outlay as process equipment being of special design and
constructed of stainless steel, is quite expensive.
20
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FIGURE 1
RECEIVING STATION
Basic Process
(Alternate
Recycling)
1. Receiving
-1
I
•H
2. Cooling
3. Storage Tanks
' I
| '
"I
h--
I
k-
I
k-
I
I
I
—®
4. Shipping
I i
©
h- @
Legend
CS - Cleaning and Sanitizing Solutions
WW - Wash Water (cold or hot)
CW = Cooling Water
EF = Effluent to drain
21
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FIGURE 2
FLUID MILK
Basic Process
1. Receiving
2 . Storage Tanks
1 _L
L_J
3. Clarification/
Standardization
(Alternative
Recycle)
! I
4. Pasteurization
5. Homo gem zation
K- ©
6. Deodorization
r-®
7 . Storage Tsnk
[—€)
i
8. Packaging
L.
Bottle Washing
9. Storage
Case Washing
10. Shipping
Legend
J
CS - Cleaning and Sanitizing Solutions
WW - Wash Water (cold or hot)
CW - Cooling Water
ST - Steam
EF - Effluent to drain
22
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FIGURE 3
CULTURED PRODUCTS
Basic .Process
-^ — f EF y
-^ (EF J— ^
Recycling
1
1
1
1
1
1
L
1 . Receiving
H ( rs )
^
2 Storage
H
1
H 1 ww )
_|
3 . Separat ion
r
I ,
i
i *
n
i
L -S^y -I
X-— X
4. Milk
Past
i
' 7. Cult
<
^ Cream
Storage
i •
eurizatlon
5 . Cream
Pasteunzat ion
|
uring
8. Cooling
1
Legend:
CS - Cleaning and Sanitizing Solution
WW - Wash Water (cold or hot)
CW - Cooling Water
ST - Steam
EF • Effluent to drain
L.
9. Packaging
10. Shipping
0
-J.
23
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FIGURE 4
By-Product s
BUTTER
Basic Process
r • " •
~-0— 1
1 . Receiving
•?. Storage Tanks
r~ ~1
Skim Milk *
)••— — (ww)
J
3. Clarification
i
4 . Separation
Alternate
5. Cooling
Recycling
1
6 . Storage Tank*:
r
— a
— ©
[•• (ww)
1
1
1
1
7 Pasteurization
,
8. Storage Tanks
r~
Bjtterm, Ik * ' 1 '
1
CS - Cleaning and Sanitizing Solution
WW - Wash Water (cold or hot)
CW - Cooling Water
ST - Steam
EF - Effluent to drain
9. Churr
A sterna 1 1 ve
l
i
ing
n
i 1
\ 13 . Continuous 1
i Buttermaking !
L 1 . Removal from
Churn
12. Packaging
K— ©
— ©
I
_j
L4. fold
Storage
24
T57 Shipping
24
-------
FIGURE 5
By-Products
NATURAL AND PROCESSED CHEESE
Basic Process
1. Receiving
Excess
Cream
L.
I"
1
^
L.
2. Storage Tanks i
3. Clarification/
Separation
Recycling
I I
. Pasteurization
Sweet Whey
5. Cheese
Manufacture
6. Press ing in
Hoops
7. Drying
Curing
12. Packaging
L3. Cold Storage
9. Process Cheese
Preparation
10. Blending
11. Pasteurization
and Cooling
.J
Legend
CS - Cleaning and Sanitizing Solution
WW - Wash Water ( cold or hot)
CU - Cooling Water
ST - Steam
EF - Effluent to drain
Shipping
25
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FIGURE 6
COTTAGE CHEESE
By-Products
Basic Process
I"
Cream
Acid Whey
Alternate
Recycling
I
I ^
1. Receiving
2. Storage
r~
-L.
' l
3. Separating
i—
i
4. Pasteurization
.j
•~l
5. Cottage Cheese
Manufacture
6. Cheese
Dressing
7 . Packaging
l ' i ! I
8. Storage
-©
Legend
9. Shipping
CS - Cleaning and Sanitiziiig Solution
WW - Wash Water (cold or hot)
CW - Cooling Water
ST - Steam
EF - Effluent to drain
26
-------
FIGURE 7
-1
i
i
L-——I——,-
I" """'- 1
27
-------
FIGURE 8
Basic Process
~l
1 H c c i?1 v i nj*
Storage Tfti ks
L.
r~
5 I'asteur i zaC i on
Alternat,
kecvclint;
|
____ |
Condensate
I
fonlm.
t-—(3
Storage Tanks
L_
Pack at; i ne,
Legend
Shipping
CS ricanln? and Sanitizing Solution
WW - ' a^h Water (cold or hot)
CU - n I i ne; Water
b T • stt am
EF - Effluent to drain
28
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FIGURE 9
DRY MILK
Basic Process
1. Receiving .
2. Storage Tanks
3 . Clan f icat ion
4, Separation
^ (wvJ)
5. Past curizatinn
(Alternate
::.--i
9 . I nstant i? i 'lu
10.
11. Storage
Lc ee ncl
1 ? . Shi ppiny,
CS - Cleamni; and Sanitizing
WW - Wa^h Wafer 'cold or hot)
CW - Cooli nt* Water
1T ^ cteam
EF = Effluent to drain
-------
FIGURE 10
CONDENSED WHEY
Basic Process
1. Receiving
1, Storage
I '
I
Alternate
Re^ycHrig
I
Condensate
I *•
1
L.
3. Pasteurization
4. Condensing
5. Cooling and
Storage
6. Packaging
7. Storage
8. Shipping
Legend
CS = Cleaning and Sanitizing, Solution
WW - Wash Water (cold or hot)
CW - Cooling Water
ST - Steam
EF - Effluent to drain
30
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FIGURE 11
DRY WHEY
Basic Process
r
1
i
1. Receiving
i
—
2. Storage
Rec_yc_Ung_ ["
1 /^!\ 1
*— —
-------
SECTION IV
INDUSTRY CATEGORIZATION
Introduction
In developing the effluent limitations guidelines and standards of
performance, a judgement must be made as to whether the dairy products
industry should be treated as a single entity or divided into subcate-
gories for the application of these guidelines and standards. The irost
cursory examination, especially if augmented by even minimal data,
indicates the inadvisability of attempting to apply a single set of
guidelines and standards to segments of an industry displaying such wide
variation in raw material input, processes employed, end products manu-
factured, and levels of waste generation. The problem then becomes one
of developing a logical subcategorization that will facilitate orderly
development of effluent limitations and standards, taking into account
the affect cf factors such as raw materials input, processes employed,
finished products manufactured, wastes discharged, age and size of
plants, and other factors.
Raw materials for dairy products processing typically consist of milk
and milk products (cream, condensed or dried milk and whey, etc.). Non-
dairy ingredients (sugar, fruits, flavors, nuts, and fruit juices) are
utilized in certain manufactured products such as ice cream, flavored
milk, frozen desserts, yogurt, and others.
A raw material may be involved in manufacture of a number of finished
products; for example, cream may serve as a raw material for such varied
finished products as fluid milk and cream, butter, ice cream, and
cultured products. Moreover, considerable variation is encountered in
the - raw materials employed in manufacture of a single product such as
ice cream. Hence, raw materials input is poorly adapted to use as a
single criterion for subcategorization, as it would require a separate
subcategory for most individual plants.
Processes Employed
The processes employed in the dairy products industry can be divided
into two groups, those essentially common to the entire industry such as
receiving, storage, transfer, separation, pasteurization and packaging,
and these employed in more limited segments of the industry such as
churning, flavoring, culturing, and freezing.
In attempting to base subcategorizatior primarily or solely on processes
employed several problems are encountered. The physical setup of dairy
products plants is seldom if ever such that it is possible to isolate
the waste discharge from a single process and thus generate the data
33
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base necessary for development of valid effluent limitations and
standards applicable tc processes. In addition, subcategorization based
on process alone fails to account for the differences in potential waste
generation that result frcnri application of a common process (e.g.,
pasteurization) to a variety of materials such as milk, cream, ice cream
mix, and whey.
Wastes _D i s c h a r cje d
Pollutants contained in the wastes discharged by dairy products plants
represent materials lost through direct processing of raw materials into
finished products and materials lost from ancillary operations. The
former group consists of milk, milk products and non-dairy ingredients
(sugar, fruits, nuts, etc.), while the latter consist of cleaners and
sanitizers used in cleaning equipment, lubricants (primarily soap and
silicone-fcased) used in certain handling equipments, and sanitary and
domestic sewage from toilets, washrooms and kitchens.
These wastes with the possible minor exceptions of some lubricants,
cleaners, sanitizers, and concentrated wheys (especially acid wheys from
production of cottage cheese), are readily degradable in typical
biological treatment systems. Any refractive materials that are
represented are generally present in such low concentrations as to pose
no taste and odor problems.
Since there are no clear cut differences (other than their
concentrations) in wastes discharged by dairy products plants,
subcategorization based on wastes dicharged would be arbitrary and
questionable.
Fini§hed_Prcducts_ManuJactured
The finished products manufactured in dairy products plants are the
results of application of specific sets of processes to selected groups
of raw materials; hence, waste discharges associated with production of
specific finished products reflect all variations attributable to raw
materials, direct production processes, and associated ancillary
operations. Therefore, a subcategorization based on finished products
has been adopted. The subcategories proposed and their associated
finished products are given in Table 7. Multiple-product plants should
be treated as weighted composites of the subcategories.
One would expect age and size of plant, modifications of process and
other miscellaneous factors tc affect the raw waste loads generated by
plants, especially for those manufacturing the same finished products,
but in general, no such correlation is borne out by the data compiled
during the course of this study. In fact, tests in several of the
newer, highly-automated plants of large size yielded higher than average
waste loads for their subcategories. Apparently any minor variations
34
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attributable to age and size of plant are overshadowed by variations
cause by "quality of management (housekeeping, maintenance, personnel
attituted, etc) raw materials input and process modifications.
Refinement of guidelines for size and age must await greater
standarizaticn of intangibles such as management which should result
from implementation of guidelines.
The exceptions to the foregoing that were noted and documented fall
within the subcategories cf receiving stations and natural cheese
plants, the least complex operations in the industry and ones in which
variation cf intangibles is minimal. Here the data indicates a
consistent difference in the waste loads generated by stations receiving
milk in cans versus those receiving milk in bulk and large versus sirall
cheese plants. This has been recognized in the guidelines by further
subdividing these sufccategories and setting separate effluent
limitations for receipt of milk in cans and receipt of irilk in bulk and
for large and small natural cheese plants.
Cn the basis of the preceeding discussion it can be concluded that, for
the purpose of establishing effluent limitations guidelines and
standards cf performance for new sources, the dairy industry can
logically be subcategorized on the basis of the type of products
manufactured.
Subcategorization can be meaningful only to the extent that a valid
basis (such as quantitive data or clearly identifiable technical
considerations) exist for developing a sound guideline or standard for
each category defined. On the basis of existing data and knowledge, it
is proposed that the dairy industry be subcategorized as indicated in
Table 7.
The typical manufacturing processes for the products that characterize
the proposed subcategories are illustrated in Figures 1 through 11.
The proposed subcategories represent single-product plants. Because of
the large number of product combinations manufactured by individual
plants in the industry and their varying proportions in relation to
total plant production, further subcategorization for multi-product
plants is impractical. Rather, it is proposed that guidelines and
standards for multi-product plants be applied on the basis of a weighted
average of the guidelines for the corresponding single product processes
(plants) , using the total EOD input for each manufacturing product as
the weighting factor.
35
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TABLE 7
Proposed Subcateggrization for the Dairy Products^Industry^
_Name_cf_Subcategory__
Products Included
Receiving Station
Fluid Products
Cultured Products
Eutter
Natural and Processed Cheese
Cottage Cheese
Ice cream. Frozen Desserts,
Novelties and ether Dairy
Desserts
Ice Cream Mix
Condensed Milk
Dry Milk
Condensed Whey
Dry Whey
Raw Milk
Market milk (ranging from 3.5%
to fat-free), flavored milk
(chocolate and other) and cream
(of various fat concentrations,
plain and whipped) .
Cultured skim milk ("cultured
buttermilk") yoghurt, sour cream,
cultured cream cheese and dips
of various types.
Churned and continuous-process
tutter.
All types of cheese
foods except cottage cheese.
Cottage cheese and cultured cream che
Ice cream, ice milk, sherbert,
water ices, stick confections,
frozen novelty products, frozen
frozen mellorine, puddings, other
dairy-based desserts.
Fluid mix for ice cream and other
frozen products.
Condensed whole milk, condensed
milk,skim milk, sweetened condensed
milk and condensed buttermilk.
Dry whole milk, dry skim milk, and
dry buttermilk.
Condensed sweet whey and condensed
acid whey.
Dry sweet whey and dry acid whey.
36
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SECTION V
WASTE CHARACTERIZATION
Sources of Waste
The main sources of waste in dairy plants are the following:
1. The washing and cleaning out of product remaining in tank
trucks, cans, piping, tanks, and other equipment performed
routinely after every processing cycle.
2. Spillage produced by leaks, overflow, freezing-on, boiling-
cver, equipment malfunction, or careless handling.
3. Processing losses, including:
(a) Sludge discharges from CIP clarifiers;
(b) Product wasted during HTST pasteurizer start-up,
shut-down, and product change-over;
(c) Evaporator entrainment;
(d) Discharges from bottle and case washers;
(e) Splashing and container breakage in automatic
packaging equipment, and;
(f) Product change-ever in filling machines.
<4. Wastage of spoiled products, returned products, or by-products
such as whey.
5. Detergents and other compounds used in the washing and
sanitizing solutions that are discharged as waste.
6. Entrainment of lubricants frcm conveyors, stackers and ether
equipment in the waste water from cleaning operations.
7. Routine operation cf toilets, washrooirs, and restaurant
facilities at the plant.
8. Viaste constituents that may be contained in the raw water which
ultimately goes to waste.
The first five sources listed relate to the product handled and
contribute the greatest amount of waste.
37
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Wastes
Materials Wasted
Materials that are discharged to the waste streams in practically all
dairy plants include:
1. Milk and milk products received as raw materials.
2. Milk products handled in the process and end products
manufactured.
3. Lubricants (primarily soap and silicone based) used
in certain handling equipment.
4. Sanitary and domestic sewage from toilets, washrooms
and kitchens.
Other products that may be wasted include:
1. Non-dairy ingredients (such as sugar, fruits, flavors, nuts,
and fruit juices) utilized in certain manufactured products
(including ice cream, flavored milk, frozen desserts, yoghurt,
and others).
2. Milk by-products that are deliberately waste, significantly
whey, and sometimes, buttermilk.
3. Returned products that are wasted.
Uncontaminated water frcm coolers, refrigeration systems, evaporators
and other equipment which does not come in contact with the product is
not considered waste. Such water is recycled in many plants. If
wasted, it increases the volume of the effluent and has an effect on the
size of the piping and treatment system needed for disposal. Poof
drainage will have the same effect unless discharged through separate
drains.
Sanitary sewage from plant employees and domestic sewage from washrooms
and kitchens is usually disposed of separately from the process wastes,
and represents a very minor part of the load.
The effect en the waste load of the raw water used by the plant has
often been overlooked. Raw water can be drawn from wells or a municipal
system and may be contributing substantially to the waste load unless
periodic ccntrol of its quality indicates otherwise.
Composition of Wastes
The principle organic constituents in the milk products are the natural
milk solids, namely fat, lactose and protein. Sugar is added in
significant quantities to ice cream and has an important effect in the
waste leads of plants producing that product. The average composition
of selected milk, milk products and other selected materials is shown in
Table 8.
38
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Cleaning products used in dairy plants include alkalis (caustic scda,
soda ash) and acids (muriatic, sulfuric, phosphoric, acetic, and others)
in combination with surfactants, phosphates, and calcium sequestering
compounds. BOD5 is contributed by acids and surfactants in the cleaning
product. However, the amounts of cleaning products used are relatively
small and highly diluted.
Sanitizers utilized in dairy facilities include chlorine compounds,
iodine compounds, quaternary ammonium compounds, and in some cases
acids. Their significance in relation to dairy wastes has not been
fully evaluated, but it is believed that their contribution to the EOD_5
load is quite small.
Most lubricants used in the dairy industry are coaps or silicones. They
are employed principally in casers, stackers and conveyors. Soap
lubricants contain EOC5 and are more widely used than silicone based
lubricants.
The organic substances in dair^ waste waters are contributed primarily
by the irilk and milk products wasted, and to a much lesser degree, by
cleaning products, sanitizing compounds, lubricants, and domestic sewage
that are discharged to the waste stream. The importance of each source
of organic matter in dairy waste waters is illustrated in Table 7.
Table 9
Estimated Contribution of Wasted Materials to the EOCji
Lead of Dairy Waste Water. (Fluid Milk Plant).
kg EOD5/kkg
(lb/1000 Ib)
Milk Eqivalent
Processed
Milk, milk products, and
ether editle materials
Cleaning products
Sanitizers
Lubricants
Employee wastes (Sani-
tary and domestic)
3. 0
0. 1
Undetermined, but
probably very small
Undetermined, but
probably small
0...1
3. 2
Percent
94%
3
100%
40
-------
The inorganic constituents of dairy waste waters have been given much
less attention as sources of pollution than the organic wastes simply
because the products manufactured are edible materials which do not
contain hazardous quantities of inorganic substances. However, the
nonedible materials used in the process, do contain inorganic substances
which by themselves, or added to those of milk products and raw water,
potentially pose a pollution problem. Such inorganic constituents
include phosphates (used as def locculants and emulsifiers in cleaning
compounds) , chlorine (used in detergents and sanitizing products) and
nitrogen (contained in wetting agents and sanitizers) .
Variability of Dairy Wastes
A significant characteristic of the waste streams of practically all
dairy plants is the marked fluctuations in flow, strength, temperature
and other characteristics. Wide variations of such parameters
frequently occur within minutes during the day, depending on the
processing and cleaning operations that are taking place in the plant.
Furthermore, there are usually substantial daily and seasonal
fluctuations depending on the types of products manufactured, production
schedules, maintenance operations, and other factors. Typical hourly
variations in flow, BOC5 and COD of a plant manufacturing cottage cheese
is illustrated in Figure 12. Figure 13 illustrates daily variations in
BOD5 strength of the waste from the frozen products drain of another
dairy plant.
It is important to recognize the highly variable nature of the wastes
when a sampling program is undertaken in a dairy plant. Unless the
daily samples are a composite of subsamples taken at frequent intervals
and proportioned in accordance with flow, results could depart
considerably from the true average values. Furthermore, the sampling
period should ideally cover enough days at various times of the year to
reduce the effect of the daily and seasonal variations.
Units
Waste loads have frequently been reported in terms of concentration or
"strength" of a given parameter in the waste stream, such as parts per
million (ppm) or milligrams per liter (mg/1) . Although a unit of
concentration can be significant as a loading factor for waste treatment
systems and for water quality analysis, it is not meaningful for control
purposes because any amount of water added to the waste stream will
result in a lower concentration, while the volume of polluting material
discharged remains unchanged. For pollution control purposes, the total
weight of pollutant discharged in a unit of time is a more meaningful
factor.
Researchers have long recognized a direct relationship in the dairy
industry between the total weight of pollutant discharged and the weight
cr volume of material processed. Waste loads of different plants can be
41
-------
FIGURE 12
-i 29
12 2
MIDNIGHT
8
10 12 2
NOON
TIME
10 12
Hourly variations in ppm BOD5, COD and waste water
fora dairy plant
42
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meaningfully compared on the basis of a unit load, such as kg (Ib) cf a
given waste parameter per kkg (1000 Ib) of raw material or product.
Up until this time, it has been the accepted practice to characterize
the raw wastes of dairy plants in relation to the number of pounds of
milk or "milk equivalent" received or processed. During this study it
was found that the "milk equivalent" concept has been defined
differently by various sources, has often been applied inconsistently,
and has at least been confusing to many people that have used waste load
data for research, management, cr control purposes.
Some of the inconsistencies between definitions cr applications of the
milk equivalent concept are a result cf arbitrary decisions that must be
made in its definition, including the following:
1. The milk equivalent of a milk product can be referred either to
raw rrilk as received from the farms, or to "whole milk" as
standardized for sale in the market.
2. Paw milk varies in composition, and therefore a conventional
sclids content must be agreed upon if the definition is to be
consistent.
3. The milk equivalent can be defined in terms of the fat solids
the ncn fat solids or the total solids of the whole milk and of
the product in question.
4. Milk products to which other than milk solids have been added
(such as ice cream or sweetened condensed milk) further
complicate the definition of a milk equivalent based on total
sclids as opposed to fat or non fat milk solids.
Because cf this situation, it is proposed that the unit waste leads
defining the effluent limitation guidelines (significantly BOD) be
expressed in terms of the total BOC5 input contained in the dairy raw
materials utilized in the production processes. This approach has the
following advantages:
1. The many arbitrary decisions involved in establishing a
definition of the "milk equivalent" concept are eliminated.
2. The EOD5 content (in Ib BOD5 per Ib of raw material) of any
given daily raw material can be determined by standard
laboratory analysis. Values for most of the typical dairy raw
materials have been published and are reasonably consistent.
Accordingly, the waste load data presented in the report have teen
Accordingly, tne waste ioaa aata presented in tne report nave
expressed in cr converted to units relating to the quantity of BOD5
the raw materials received or processed.
in
44
-------
To maintain consistency in the application the waste load data and
guidelines set forth in this report it is essential that the procedures
set forth in this repcrt be adopted as standards to calculate the waste
load of any particular plant. For simplicity, only the process raw
materials are considered in the computations; it must be remembered,
however, that EOD5 can also be contributed by lubricants, detergents,
sanitizers, and in some cases, sanitary sewage.
Available data indicates that the daily average EOD5 strength of dairy
plant wastes varies over a bread range, from as low as 40 mg/1 to higher
than 10,000 mg/1, with the great majority of plants falling within 1,000
to 4,000 mg/1. A summary of available raw waste BODJ data appears in
Table 10.
In expressing BOD5 less per EOD5 received (processed) it is convenient
and useful to express the unit load as kg (Ib) BOD5 of waste discharge
per 100 kg (Ib) received processed for two reasons.
1. kg BOD5/100 kg (lb/100 Ib) can be read directly as per cent
EOD5 loss, i.e., for ice cream plants the mean loss is 14.8
kg/Too kg (14.8 lb/100 Ib) or directly, 14.8 percent.
2. kg BOD5/100 kg BOD5 (Ib BOD5/100 Ib BOD) is equal to kg
EOCjj/1000 milk equivalent when the raw material is whole milk,
since the BODJ of whole milk is approximately 10 percent by
weight.
Mean unit EOE5 loads for plants range from 0.41 kg/100 kg BOD5 or 0.41
kg/1000 kg M.E., (0.41 lb/100 Ib BOD5 or 0.41 Ib pr 1000 Ib M.E.) for
receiving stations to 16.8 kg/100 kg BOD5 or 14.6 kg/1000 kg M.E. (16.8
lb/100 Ib EOD5 or 14.6 lb/1000 Ib M.E.) for cottage cheese plants. In
general, the relative magnitudes of the mean unit BOD5 loads for the
various subcategories are as would be expected when considering the
viscosity and BOD5 content of the product and the nature of the
processes.
COD
Chemical Oxygen Demand (COD) is the amount of equivalent oxygen required
for oxidation of the organic solids in an effluent, measured by using
chemical oxidizing agents under certain specified conditions instead of
using microorganisms as in the BOD test. It can be used alternatively
to BOD5 as a measure of the strength of the waste water. The advantages
of the COD test over the BOD5 is that it can be completed in a
relatively short time and there is generally a lesser chance for error
in performing the test.
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There is disagreement, however, on the accuracy and relative merits of
each test in determining the oxygen demand of a dairy effluent. In
spite of being more cumbersom, and inherently providing a greater
chance of error, the ECD5 test has been much more widely used in the
past. The results of the BOD5 test have been regarded as more
significant, because it was considered to more nearly parallel what is
actually taking place in natural waters. Many dairy companies in the
United States have reportedly attempted to use the COD test but have
discontinued the practice because of the wide variation in EOE:COD
ratios measured.
More recently, the need for the COD test as a supplement the BOD5 test
has been recognized, and many investigations consider it a better method
for assessing the strengths of dairy effluents.
A summary of BOD:COB data appears in Table 11. Significant variations
of the ratio are evident; the overall range of the EOD:COD ratio for raw
effluents reported from all sources is 0.07 to 1.03. The mean for
identified plants is 0.57. This figure can be used as a conversion
factor.
Sclids
The concentrations of suspended solids in raw dairy plant wastes vary
widely among the different dairy operations. The greatest number of
plants have suspended solids concentrations in the 400 mg/1 to 2000 mg/1
range.
The data on the suspended solids content of raw wastes of identified
plant sources are summarized in Table 12. The mean suspended solids
loads range from a low of 0.03 kg/100 kg BCD5 (0.03 kg/1,000 kg M.E.)
for milk receiving stations to a high of 3.50 kg/100 kg EOD5 1.78 kg/kkg
M.E.) for ice cream plants. Data were not available for dry milk,
cultured products, cottage cheese, and can receiving stations operations
as single product categories. The suspended solids would be composed
primarily of coagulated milk, fine particles of cheese curd and pieces
of fruits and nuts from ice cream operations.
In all but two cases the suspended solids content of raw wastes was
lower than the BOD5 value. Further, there did seem to be a significant
correlation between the suspended solids content of raw wastes and the
type of plant operation. This fact is supported by an analysis of
suspended solids to BOD5 ratios for identified plant source data. The
values of the suspended solids - BOD5 ratio were found to be distributed
about a mean of 0.415 with a standard deviation of 0.32. This yields a
coefficient of variance of 77 percent. With 3 highest and lowest values
eliminated frcm the sample, the mean and standard deviation become 0.368
and 0.155 respectively, giving a correlation of variance of 42 percent.
Further, a regression analysis of the data the suspended solids and EOD5
47
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data pairs resulted in the following relationship with a correlation
coefficient of 0.92. Suspended solids = 0.529 BOD5 - 152.2.
This relationship between suspended solids and BOD5 seems to hold ever
the range of BOD5 normally found in raw dairy plant wastes, i.e., 1,000
mg/1 to 4,000 mg/1. Using the above equation and the lower and upper
limits of range of 1,000 mg/1, and 4000 mg/1 suspended solids - EOD5
ratios of 0.38 and 0.49 respectively are found.
Despite the relatively constant ratio of suspended solids to BOD5 of
about .40 for the dairy industry as an aggregate, there is some evidence
that the ratio may be somewhat higher for cottage cheese,, ice cream, and
drying operations where large amounts of fines could potentially be
wasted. Substantiation of this hypothesis must await further data and
analysis.
ES
The pH cf dairy wastes of a total of 33 identified plcints varies from
4.0 to 10.8 with an authentic mean of 7.8. The main factor affecting
the pH of dairy plant wastes is the types and amount of cleaning and
sanitizing compounds discharged to waste at the plant.
Temperature
Values reported by 12 identified plants for temperatures of raw dairy
wastes vary from 8° to 38°C (46°F to 100°F) with a mean of 24°C (76°F) .
In general the temperature of the waste water will be affected primarily
by the degree of hot water conservation, the temperature of the cleaning
solutions, the relative volume of cleaning solution in the waste water.
Higher temperatures can be expected in plants with condensing
operations, when the ccndensate is wasted.
Phosphorus concentrations (as FOjf) of dairy waste waters reported by 29
identified plants range from 9 mg/1 to 210 mg/1, with a mean of 48 mg/1.
Part of the phosphorus contained in dairy waste water comes from the
milk or milk products that are wasted. Waste water containing 1% milk
would contain about 12 mg/1 of phosphorus (3) . The bulk of the
phosphorus, however, is contributed by the wasted detergents, which
typically contain significant amounts of phosphorus. The wide range of
concentraticns reported reflect varying practices in detergent usage and
recycling cf cleaning solutions.
Nitrogejj
50
-------
Ammonia nitrogen in the waste water of 9 identified plants varied
between 1.0 rng/1 and 13.4 mg/1, with a mean of 5.5 mg/1 . Total nitrogen
in 10 plants ranged from 1.0 rrg/1 to 115 mg/1, with a mean of 64 mg/1.
Milk alone would contribute about 55 mg/1 of nitrogen at a 1% (10,000
mg/1) concentration in the waste water. Quaternary ammonium compounds
used for sanitizing and certain detergents can be another source of
nitrogen in the waste water.
Chloride
Six identified plants reported chloride concentrations ranging from 46
mg/1 to 1,930 mg/1; the mean was 483 mg/1. The principal sources of
chloride in the waste stream may include brine used in refrigerator
systems and chlorine based sanitizers. Milk and milk products are
responsible fcr part of the load; at a 1% concentration in the waste
water, milk wculd contribute 10 mg/1 of chloride.
Wat er_ Volume
Waste water volume data are shown in Tables 13 (in metric units) and 13A
(in English units) .
Waste water flow for identified plants covers a very broad range from a
mean of 542 1/kkg milk equivalent (65 gal per 1,000 Ib, M.E.) for
receiving stations to a mean of over 9,000 1/kkg milk equivalent (ever
1,000 gal pr 1,000 Ib M.E.) for certain multiproduct plants. It should
be noted that waste water flow does not necessarily represent total
water consumed, because many plants recycle condenser and cooling water
and/or use water as a necessary ingredient in the product.
peterm_il3;i23 2^i£Y E§§^§ Loads
Prior research has shown that a major controlling factor of the raw
waste leads of dairy plants is the degree of knowledge, attitude, and
effort displayed by management towards implementing waste control
measures in the plant. This conclusion was reaffirmed by the
investigations carried out in this study.
Good waste management is manifested in such things an adequate training
of employees, well defined job description, close plant supervision,
good housekeeping, proper maintenance, careful production scheduling,
finding suitable uses or disposal methods for whey and returned products
other than discharge to drain, salvaging products that can be reused in
the process or sold as feed, and establishing explicit waste reduction
programs with defined targets and responsibilities. Improvement in
those areas generally will not require inordinate sums of money nor
complex technologies to be implemented. In fact, most waste control
measures of the type indicated will have an economic return as a result
of saving product that is otherwise wasted.
51
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The other principal factors determining the raw waste load, including
EOD^ of the inputs and products, viscosity of materials, and processes
employed have been discussed elsewhere in the report.
Polluting
It has been generally recognized that the most serious polluticnal
problem caused by dairy wastes is the depletion of: oxygen of the
receiving water. This comes about as a result of the decomposition of
the organic substances contained in the wastes. Organic substances are
decomposed naturally by bacteria and other organisms which consume
dissolved oxygen in the process. When the water does not contain
sufficient dissolved oxygen, the life of aquatic flora and fauna in the
water body is endangered.
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SECTION VI
POLLUTANT PARAMETERS
Vvaste water Parameters of Potential
PollutionaInsignificance
On the basis of all evidence reviewed, it has been concluded that
the waste water parameters of potential pollutional significance include
EOD, COD, suspended solids, pH, temperature, phosphorus in the form of
phosphates, nitrogen in various forms (e.g., ammonia nitrogen and
nitrate nitrogen), and chlorides. The significance of these parameters
and the rationale for selection or rejection of each as a factor for
which an effluent guideline should be established are discussed below.
BOD
The majority of waste material in dairy plant waste waters is
organic in nature, consisting of milk solids and organic components of
cleaners, sanitizers and lubricants. The major pollutional effect of
such organics is depletion of the dissolved in receiving waters. The
potential of a waste for exerting this effect most commonly has been
measured in terms of BOD, the laboratory analysis which most closely
parallels phenomena occurring in receiving waters.
The BOC5 concentration of raw waste waters in the dairy products
processing industry typically ranges from 1,000 mg/1 to 4,000 mg/1 and
the total daily loads within the industry have been observed to range
from 8.2 kg/day (18.0 Ib) to 3,045 kg/day (6,699 Ib). This is
equivalent to raw waste discharge for municipalities of 100 to 40,000
population. Such concentrations of BOD5 are considered excessive for
direct discharge to receiving waters, and unless the receiving waterbody
is a large, well-mixed lake or stream, the upper segment of the range of
loads poses a hazard to aquatic wildlife as a result of oxygen
depletion.
The ECCjS level of dairy wastes can be reduced by in-plant controls
and end-of-pipe treatment (including disposal on land) that are well
demonstrated and readily available. Therefore, effluent limitations
guidelines for this parameter are justifiable and recommended for point
source discharges for each subcategory within the dairy products
industry.
COD
In theory, the Chemical Oxygen Demand test (an analytical procedure
employing refluxing with strong oxidizing agents) measures all
oxidizable organic materials, both non-biodegradable and biodegradable,
in a waste water. It thus has an advantage, when conpared to the ECD^
test, of measuring the refractive organics which, may cause toxicity or
55
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taste and odor problems. An additional advantage (especially for
employment as an operational waste management tool) is that COD can be
determined in a relatively short period of time, at most a matter of
several hcurs not days, and thus is a measure of current operations, not
these of days past as is true for BOD. Conversely, COD has two major
disadvantages. It does not closely parallel phenomena in receiving
waters and it does not distinguish between non-biodegradable and
biodegradable materials. Thus, it does not indicate the potential that
a waste water may have for causing an oxygen depletion in receiving
waters.
Data compiled during the course of this study indicate a COD to EOD5
ratio of approximately 2:1 for raw wastes and 4:1 for biologically
treated (e.g., activated sludge) wastes. Both of these ratios are faily
close to these noted for typical municipal wastes and do not indicate
wastes abnormally high in refractive organics.
The decision of whether or not to include COC as a parameter to be
controlled under effluent guidelines should be based on the answers to
two guesticns. What is the significance of the materials measured by
CCD and net by other parameters, and what are the facts associated with
treatment fcr removal cf COD?
Historically there is little or no information to indicate
environmental problems associated with an inherent toxicity of dairy
plant wastes, the impacts on aguatic life having been mediated through
oxygen depletion attributable to biodegradable organics. Similarly, the
limited taste and odor problems have been associated primarily with
intermediate products resulting from biological breakdown (especially
under anaerobic conditions) of the degradable organic constituents of
irilk.
Dairy prcduct plants that can establish reasonably consistent
correlation between COD and BOD5 could, in the future, substitute COD
for BOD. This is especially true for small isolated operations that
could not afford Total Organic Carbon or Total Oxygen Demand
determinations at some later date.
Syspended^Solids
Suspended solids in waste water have an adverse affect on the
turbidity of the receiving waters. This is particularly noticible for
waste water from dairy products due to the color of the solids and their
extreme opacity. An additional effect of suspended solids in quiescent
waters is the build-up of deposits on the botton. This is especially
objectionable when the suspended solids are primarily organic materials,
as is the case in dairy wastes. The resulting sludge beds may exert a
heavy oxygen demand on the overlying waters, and under anaerobic
conditions their decomposition produces intermediate products (e.g.,
56
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hydrogen sulfide) which cause odor problems and are toxic to aquatic
life.
Dairy products waste waters typically contain up to 2,000 mg/1 of
suspended solids, most of which are organic particulates derived from
the irilk and other materials processed. The level of solids in raw
waste waters can be reduced by good in-plant control and with adequate
end-of-pipe biological treatment and clarification can be reduced to
acceptable concentrations in final discharge waste waters. It is
recommended, therefore, that suspended solids be included in the
parameters to be controlled under effluent guidelines and standards.
ES
pH outside of an acceptable range may exert adverse effect either
through direct impact of the pH or through their role of influencing
other factors such as solubility of heavy metals. Among the potential
adverse effects of abnormal pH are direct lethal or sub-lethal impact on
aquatic life, enhancement of the toxicity of other substances, increased
corrosiveness of municipal and industrial water supplies, increased
costs for water supply treatment, increased staining problems associated
with greater solubility of substances such as iron and manganese, and
rendering water unfit for some processes such as canning or bottling of
certain foods and beverages.
Though a number of individual waste streams within a dairy products
plant may exhibit undersirably high or low pH, the available data show
that the combined discharge from dairy plant generally fall with the
acceptable range. However, monitoring and adjustment of pH are
relatively simple and inexpensive, so there is no real reason for
discharge cf waste water that is outside the acceptable range of pH.
In view cf the many potential adverse effects of abnormally high or
low pH, and the ease of measurement and control, it is recommended that
pH be included in the parameters for effluent guidelines and standards.
Available data (Table 14) indicates that temperature of raw waste
waters range between 8°C (46°F) and 38°C (100°F) , with 90 percent of the
discharges ranging between 15°C (59°F) and 29°C (85°F) . These values,
coupled with volumes of discharge in the industry, indicate that neither
temperature nor total heat discharge constitute serious problems.
Furthermore, there will be a tendency for the waste waters to approach
ambient temperature as they pass through the treatment facilities that
must be installed for point source discharges to meet BOE5 limitations.
Thus, temperature has not been included in the parameters subject to
guidelines and standards.
Phosphorus
57
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Phosphorus is of environmental concern because of the role it plays
in eutropbication, the threshold concentration for stimulation of
excessive algal growth generally being considered as approximately 0.01
mg/1 to 0.25 mg/1.
Phosphorus concentrations in raw waste waters in the diary industry
have been fcund to range from 12 mg/1 to 210 mg/1 with a mean of 49
mg/1. With the reduction of phosphorus concentrations that result from
implementation of adequate in-plant control, and the further reduction
that accompanies biological treatment (approximately 1 part per 100
parts of ECE^ removed), the phosphorus levels associated with point
source discharges in the industry will be consistent with those in
discharges from municipal secondary treatment plants. Effluent
guidelines and standards for phosphorus are not recommended at this
time.
Nitrogen
Nitrogen is another element whose major cause for environmental
concern stems from its role in excessive algal growth. In addition,
very high levels of nitrogen are undesirable in water supplies and are
toxic to aquatic life especially when present in the form of ammonia.
Nitrogen is present in dairy waste waters primarily as protein and
ammonia nitrogen. Based on very limited data (Table 14), ammonia
nitrogen concentrations have been found to vary from 1.0 mg/1 to 13.2
mg/1 and average 5.4 mg/1. As is the case for phosphorus, reductions
attained through in-plant controls and biological treatment required to
meet limitations for other parameters will result in nitrogen
concentrations in point source discharges that are consistent with those
found in discharges from municipal secondary treatment plants. Effluent
limitations for nitrogen are not recommended for application to the
dairy products industry at the present time.
Chloride
Excessive concentrations of chloride interfere with use of waters
for municipal supplies by imparting a salty taste, for industrial
supplies by increasing corrosion, for irrigation through phytotoxicity,
and for propagation of freshwater aquatic life (if levels are in
thousands of mg/1 and variable) through disturbance of osmotic balance.
Very limited data (Table 14) show that chloride concentrations in
raw waste waters range between 46 mg/1 and 1,930 mg/1 and average 482
mg/1. If one eliminates the very high value of 1,930 mg/1, possibly
attributable to leakage of brine from refrigeration lines, the chlcride
concentrations are well below limits for any use other than irrigation
of the most sensitive plants. Chloride is a conservative pollutant,
i.e., it is not subject to significant reduction in biological treatment
59
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systems. Appreciable reduction of chloride would require advanced
treatment such as reverse osmosis or ion exchange.
In view of the relatively low levels of chlorides encountered and
the difficulty and of their removal, effluent guidelines and standards
are not recommended for chlorides.
60
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SECTION VII
CONTROL AND TREATMENT TECHNOLOGY
In-Plant_Ccntrcl_Cgncepts
The in-plant control of water resources and waste discharges in all
types of dairy food plants involve two separate but interrelated
concepts:
1. Improving management of water resources and waste
materials.
2. Engineering improvements to plant, equipment, processses,
and ancillary systems.
li§Qt_Mana2ement_Improvement
Management is one key to the control of water resources and waste within
any given dairy plant. Management must be dedicated to the task,
develop positive action programs, and follow through in all cases; it
must clearly understand the relative role of engineering and management
supervision ir plant losses.
The best modern engineering design and equipment cannot alone provide
for the ccntrcl of water resources and waste within a dairy plant. This
fact was clearly evident again during this study. A new (six-month
old), high-capacity, highly automated multi-product dairy plant,
incorporating many advanced waste reduction systems, was found to have a
EOD5 level in its waste water of more than 10 kg/kkg (10 lb/1000 Ib) of
irilk equivalent processed. This unexpected and excesssive waste could
be related directly to lack cf management control of the situation and
poor operating practices.
Management ccntrol of water resources and waste discharges ideally
involves all cf the following:
- Development by management of an understanding of the need for
waste control, the economic benefits to be accrued, and a complete
understanding of the factors involved in water and waste control.
-Utilization of a continuing educational program for super-
visors and plant personnel.
Assignment of waste management control to a specific
individual in the management system, and establishment of a "waste
control committee."
Development of job descriptions for all personnel to clearly
delineate individual responsibilities.
61
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- Installation and use of a waste monitoring system to evaluate
progress.
- Utilization of an equipment maintenance program to minimize
all product losses.
Utilization of a product and process scheduling system to
optimize equipment utiliztion, minimize distractions of personnel, and
assist in waking supervision of the operation possible.
Utilization of a planned quality control program to minimize
waste.
- Development of alternative uses for a wasted products.
- Improvement of processes, equipment and systems as rapidly as
economically feasible.
- Provide an environment to permit supervisors to effectively
supervise waste mangement.
Waste_Menitcring
The collection of continuous information concerning waster usage and
waste water discharge is essential to the development of any water and
waste control program in a dairy plant. Much of the excess water and
high solids waste discharges to sewer result from lack of information to
plant personnel, supervisors and management. In many instances, large
quantities of potentially recoverable milk solids are discharged to the
drain without the knowledge of mangement. Accounting systems utilized
to account for fat and solids within a diary plant are frequently
inaccurate because of many inherent errors in sampling, analysis,
measurement of product, and package filling. The installation of water
meters and of a waste monitoring system has generally resulted in econ-
omic recovery of lost milk solids. Recovery is usually sufficient to
pay for costs of the monitoring equipment within a short time.
Water meters may be be installed en water lines going to all major
operating departments in order to provide water use data for the
different irajcr operations in the plant. Such knowledge can be used to
develop specific water conservation programs in a more intelligent
manner. Seme plants have found it advantageous to put in water meters
to each irajcr process to provide even more information and to fix
responsibility for excessive water use.
Waste monitoring equipment generally should be installed at each
outfall from the plant. Wherever possible in older plants, multiple
outfalls should be combined to a common discharge point amd a sampling
manhole installed in this location. Where sampling manholes are being
installed for the first time in old or new locations, attention should
62
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be given to insuring that there is easy and convenient access to the
sampling pcint.
Monitoring equipment generally would include, a weir to measure flow
volume and a continuous sampling device. Two types of samplers may be
utilized: (a) a proportional flow, composite sampler such as the
Trebler, cr (b) a time-activated sampler that can provide hourly
individual samples. For plant control purposes the latter can provide
the waste control supervisor and and employees with a visual daily
picture of the wastes from the plant even without sampling the
turbidity, color, presence of free fat, or sediment. Such a daily
evaluation can readily point cut problem areas. In the case of the time
sampler it is necessary to utilize flow data to make up a flow propor-
tioned composite sample for analysis.
Many equipment, process, and systems improvements can be made within
dairy food plants to provide for better control of water usage and waste
discharges. In many cases significant engineering changes can be made
in existing plants at a minimal expense. The application of engineering
improvements must be considered in relationship to their effect on water
and waste discharges and also on the basis of economic cost of the
changes. Many engineering improvements should be considered as "cost
recovery" expenditures, since they may provide a basis for reclaiming
resources with a real economic value and eliminating the double charges
that are involved in treating these resources as wastes.
New plants or extensive remodeling of existing plants provide an even
greater opportunity to "engineer" water and waste reduction systems.
Incorporation of advanced engineering into new plants provides the means
for the greatest reduction in waste loads at the most economical cost.
Existing Plants
- Equipment improvements
- Process improvements
- System improvements
New Plants or Expandsion of Existing Plants
- Plant layout and equipment selection
5i§§i§ Maggement Through Equipment Improvements^
Waste management control can be strengthened by upgrading existing
equipment in plant operations. These can be divided into: (a)
61
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improvements that have been recommended for many years and (b) these
that are new and not widely used or evaluated.
Standard Equipment Improvement Recommendations
1. Put automatic shut-off valves on all water hoses so that
they cannct run when not in use.
2. Cover all drains with wire screens to prevent solid
materials such as nuts, fruits, cheese curd form going down the drain.
3. Mark all hand operated valves in the plant, especially
multiport valves, to identify open, closed and directed flow positions
to minimize errors in valve operation by personnel.
4. Identify all utility lines.
5. Install suitable liquid level controls with automatic pump
stops at all points where overflow is likely to occur (filler bowls,
silo tanks, process vats, etc.). In very small plants,, liquid level
detectors and an alarm bell may be used.
6. Provide adequate temperature controls on coolers,
especially glycol coolers, to prevent freezing-on of the product and
subsequent product loss. In some instance high-temperature limit
controls may be installed to prevent excessive burn-on of milk which not
only increase solids losses but also increase deeming compound
requirements.
7. All CIP lines should be checked for adequate support.
Lines should be rigidly supported to eliminate leakage of fittings
caused by excessive line vibrations. All lines should be pitched to a.
given drain pcint.
8. Where can receiving is practiced in small plants, an
adequate drip saver should be provided between can dumping and can
washing. This should be equipped with the spray nozzle to rinse the can
with 100 ml (3-4 oz) of water. A two minute drain period should be
utilized before washing.
9. All piping around storage tanks and process areas where
pipelines are taken down for cleaning should be identified to eliminate
misassembly and damage to parts and subsequent leaking of product.
10. Provide proper drip shields on surface coolers and fillers
so that no spilled product can reach the floor.
11. All external tube chest evaporators should be designed
with a tangential inlet from the tube chest to the evaporating space.
64
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All ceil or clandria evaporators should be equipped with efficient
entrainment separators.
12. "Splash discs" on top of the evaporators can prevent
entrainmert losses through improper pan operation.
13. Evaporators and condensers should be equipped, wherever
possible, with full barcmetic leg to eliminate sucking water back to the
condenser in case of pump or power failure.
New Concepts For Consideration In Equipment Improvement
1. Install drip shields on ice cream filling equipment to
collect frozen product during filling machine jams. Such equipment
would have to be specially designed and built at the present time.
2. Install a system for collecting novelties from frozen
dessert ncvelty machines and packaging units. At the present time
numerous types of failures, especially on stick novelty machines, cause
defective novelties to be washed down the drain. Such defects include
tad sticks, nc sticks, poor stick clamping, overfilling, and poor
release. The "defective product collection system" would have to be
specially designed and custom built at the present time.
3. Since recent surveys have shown that case washers may use
up to 109? of the total water normally utilized in a total plant
operation, automatic shut-off valves on the water to the case washer
should be installed so that the case washer sprays would shut-off when
the forward line of the feeder was filled. Many cases are exposed to
long term sprays because of relatively low rate of stacking and use of
washed cases in many operations. Another alternative to be shut-off
valve would be an integrated timer coupled to a trip switch in which the
trip switch would activate the washer sprays which would automatically
shut-down after a specified washing cycle.
4. Install a product recovery can system, attached to a pump
and piped to a product recovery tank. Such a system should be installed
near filling machines, (including ice cream) to provide a system for
placing the product from damaged cartons or non-spoiled product return.
Such product could be sold for animal feed.
5. Develop a "non-leak" portable unit for receiving damaged
product containers. Currently used package containers are not liquid
tight and generally leak products onto the floor. This is particularly
undersiable fcr high solids products materials such as ice cream.
6. Install an electrical interlock between the CIP power cut-
on switch and the switch for manual air blow down, so that the CIP pump
65
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cannot be turned on until after the blow down system has purged the line
cf product.
7. Equip filling machines for most fluid products with a
product-capture system to ccllect products at time of change over from
one product tc another. Most fillers have a product by-pass valve. An
air-acutated by-pass valve interlocked with a low level contrcl could be
piped to the filler product recovery system or the container collecting
the product from drip shields; so designed that when the product in the
filler bcwl reaches the minimal low level the product by-pass systems
would open, the product would drain, followed by a series of short
flushing rinses. Filler bowls could be equipped with small scale spray
devices for this purpose. The entire system could be operating through
a sequence timer. All the components of such a system are readily
available hut the system would have to be designed and built for each
particular filler at the present time.
8. In the future, there is a need to give attention tc the
design of equipment such as fillers and ice cream freezers to permit
them to be fully CIP cleaned.
In the context of this report a "system" is a combination of operations
involving a multiplicity of different units of equipment and integrated
to a common purpose which may involve one or more of the unit processes
of the dairy plant. Such systems can be categorized into: (a) those
that have been put in use in at least one or more dairy plants, and (b)
those that have not yet been utilized but are technolgically feasible
and for which component equipment parts now exist.
(a) Waste Control Systems Now In Use:
Systems which are currently in use that have a direct impact on
decreasing dairy plant wastes include the following:
CIP cleaning systems
HTST product recovery systems
(for fluid products and ice cream)
Air blow down
Product rinse recovery systems
Automatic processes
1. CIP - The management of cleaning systems for dairy plants
has signifcance to waste discharges in three respects: (a) the amount
of milk solids discharged to drain through rinsing operations, (b) the
66
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concentration of detergents in the final waste water, and (c) the aircunt
of milk solids discharged to drain as the result of the cleaning
cpertion itself. The cleaning of all dairy equipment, whether done by
irechnaical fcrce or hand cleaning, involves four steps: pre-rinse,
cleaning, postrinse, and sanitizing.
Wherever possible, circualtion cleaning procedures are replacing the
hand-cleaning operations primarily because of their greater efficiency
and concomitant result in improving product quality. Since cleaning
compounds have been shown to be deleterious to the microflora of dairy
waste treatment systems, all cleaning systems should take into account
both water utilization and cleaning compound utilization.
In small plants where hand-cleaning cannot be economically avoided, a
system should be developed to pre-package the cleaning compounds in
amounts just sufficient to do each different type of cleaning job in the
plant. This will avoid the tendency of plant personnel to use much more
cleaning compound than necessary. A wash vat for hand cleaning should
be provided that has direct connection to the plant hot water system and
incorporates a thermostatically controlled heater to maintain the tank
temperature at or around 50c°c (120°F). High-pressure spray cleaning
units should be used for hand cleaning of storage tanks and process
vessels tc improve efficiency and reduce cleaning compound usage.
Cleaning compounds should be selected for a specific type of operation
and the different types of compounds kept at a minimum to eliminate
confusion, loss of materials, and utilization of improper substances.
Small parts such as filler parts, homogenizer parts and separator parts
from those machines needing tc be hand-cleaned should be cleaned in a
well-designed COP (cleaned-out-of-place) circulation tank cleaner
equipped with a self-contained pump and a thermostically controlled
heating system.
For maximum efficiency, minimum utilization of cleaning compounds, and
maximum potential use of rinse recovery systems, as much of the plant
equipment as possible should be CIP. Two types of CIP systems are
currently in use in the dairy industry:
-Single-use: the cleaning compound is added to the cleaning
solution and discharged to drain after a single cleaning
opeation.
- Multiple-use: the cleaning compound is circulated through
the equipment to be clened and returned to a central cleaning
tank for reutilization. The cleaning compound concentration is
maintained at a desired level either by "recharging" or by
using contactivity measurements and automatic addition of
detergent as required.
67
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There is a conflict within industry as to which method is best from the
viewpoint of cleaning compound (detergent) and water usage. In
principle it would appear that the reutilizaticn of the detergent
solution should be the most economical in respect to water and cleaning
compound requirements. Under actual practice this has not always teen
the case and in some instance the highest water and cleaning compound
utilization has been in plants equipped with mutiple-use CIP systems.
On the average, single-use systems use less cleaning compound and
slightly mere water than multiple or reuse systems.
Automation of a CIP system provides for maximum potential waste control,
both in respect to product loss and detergent utilization., An automated
CIP system is composed of necessary supply lines, return lines, remote
operated valves, flow control pumping system, temperature control system
and centralized control unit to operate the system.
These systems have to be designed with safety in rnind as well as
efficiency. A major problem in most current designs is Inadequate air
capacity to completely clear the lines of product and dependency upon
plant personnel to make sure that they are used prior to initiation of
the CIP cleaning operation.
2. Product Rinse Recovery - The automated CIP system and product
recovery system for the HTST pasteurizer can also be expanded to include
rinse recovery for all product lines and receiving operations.
3. Post Rinse Utilization System - Final rinses and sanitation
water may be diverted to a holding tank for utilization in prerinsing
and wash water make-up for single use CIP application.
14. Automated Continuous Processing - Fluid products,, including ice
cream mix, can be prepared in a continuous, sequential manner
eliminating the need for special processing vats for various products,
eliminating the need to make a change-over in water between products
that are being pasteurized. Such systms are curently in use for milk
products and could be developed for ice cream operations.
(b) New Viaste Control Concepts
A number of new waste control systems using existing components and
electrical and electonic control systems may be developed in the future
tc further reduce waste loads in diary plants.
Waste^Mangement_Thrgugh_ProBer_Plant_IaYOut_and_Eguir)inent_ Selection
Proper layout and installation of equipment designed to minimize waste
are important factors to achieve low waste and low water consumption in
new or expanded plants.
(a) Plant Layout
68
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Whereas the principles involved apply to all dairy food plants, they are
most critical for large ones. The pcint is approaching when 80% of the
dairy products will be produced in less than 30% of the plants. Thus,
irajcr waste discharges will be associated with a relatively few very
large plants. For such operations, attention to plant layout is
essential.
Some majcr features in plant design which will minimize waste leads
include:
1. The use of a minimum number of storage tanks. A
reduction in the number of tanks reduces the number of fittings,
valves, pipe length, and also reduces the amount of wash water
and cleaning scluticn required. Also, the loss due to product
adhering tc the sidewalls to tanks is minimized by using fewer
and larger tanks.
2. Locating equipment in a flow pattern so as to
reduce the amcunt of piping required. Fewer pipes mean
fewer fittings, fewer pumps and fewer places for leakage.
3. Segregation of waste discharge lines on a
departmental basis. Viaste discharge lines should be designed
so that the wastes from each major plant area can be identified
and, ideally, diverted independently of other waste discharges.
This would permit identification of problems and later application
of advanced technology to divert from the sewer all excessive
discharges - such as accidental spills.
4. Storage tanks should be elevated and provide for
gravity flew to processing and filling equipment. This
allows for irore complete drainage of tanks and piping, and
reduces pumping requirements.
5. Space for expansion should be provided in each
departmental areas. This will permit an orderly expansion
without having to install tanks and equipment at remote points
from existing equipment. Only the equipment needed for current
production (or production for the next three years) should be
installed at the time of building the plant. This eliminates
the tendency to operate a number of different pieces of
related equipment under-capacity to "jusitify" their presence
in the plant. Such surplus equipment, especially pasteurizers,
tends to increase waste loads and require additional maintenance
attention.
6. Hand-cleaned tanks should be designed to be high
enough frcm the floor to permit draining and rinsing.
(b) Equipment Selection
69
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In new or remodeled plants, attention must also be given to the
selection of equipment, processes and systems to minimize water usage
and waste discharge. The following considerations are applicable to
these concepts and may be beneficial to overall plant efficiencies and
operations.
1. Evaluation of equipment for ease of cleaning. Equipment
should be designed to elimate dead space, to permit complete draining,
and be adaptable to CIP (clean in place) . Use of 3A-approved equipment
is to be encouraged, since these cleanability factors are included in
the approval process.
2. Use CIP air"- actuated sanitary valves in place of plug
valves. They fall shut in case of actuator failure, reduce leaks In
piping systems, are not taken down for cleaning and therefore receive
less damage and require less maintenance. Such valves are the key to
other desirable waste management features such as automated CIP systems,
automated process control, rinse recovery systems, and air blowdown
systems.
3. Welded lines should be used wherever possible to reduce
leaks by eliminating joints and fittings.
4. For pipes that must be disconnected, use CIP fittings that
are designed not to leak and require minimum maintenance.
5. CIP systems should be used wherever possible. In all new
installations, these should be automated to eliminate human errors, to
control the use of cleaning compounds and waters, to improve cleaning
efficiencies and to provide basic systems for use in future engineering
proceesses for waste control.
6. Install a central hot water system. Do not use steam "T"
mixers" they waste up to 50% more water than a central heating system
for hot water.
7. Evaluate all available processes and systems for waste
mangement concepts.
Through Improvement of_ Plant Management and
Assessment of the extent to which in-plant controls can reduce dairy
plant wastes is difficult, because of the many different types of
plants, the variability of management, and the lack of an absolute model
on which to base judgement. Eased on limited data, it would appear
probable with current management, equipment, processes and systems that
have been utilized anywhere in the industry, the best that could be
70
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achieved in most plants would be a water discharge of 830 1/kkg (100
gal/ 1,0000 Ib) of milk equivalent processed, and a EOD5_ discharge of
0.5 kg/kkg (0.5 lb/100lb) of milk equivalent processed. This would be
equivalent to a EOE5 waste strength minimum of 600 mg/1. The
achievement cf such levels have been demonstrated only in a few
instances in the industry and in all cases these have been in single-
product plants not involving ice cream and cottage cheese.
Vvaste Reduction Possible Through Management
The extent tc which management can reduce water consumption and and
waste loads would depend upon a number of factors that do not lend
themselves tc objective evaluation, such as the initial quality of
management, the current water and waste loads in the operation, and the
type and effiency of implementation of control programs within the
plant. No absolute values can be ascertained. Nor is it possible to
assign individual water and waste discharge savings to specific aspects
of the plant management improvement program; rather, the problem can
only be locked at subjectively in the context of its whole. The
consensus among those who have studied dairy plant waste control
recently (Harper, Zall, and Carawan) is that under most circumstances
mangement improvement generally can result in a reduction equivalent to
50% of current load.
Although there are exceptions, there has been a general relationship
found between waste water volume and EOD5 concentrations in dairy plant
waste waters. For most plant operations the waste discharge could be
reduced tc a rate of 1,660 I/ kkg (200 gal/1000 Ib) of milk equivalent
processed and 2.4 kg BOD5_. The reductions achievable represent a real
economic return to the operation. Each kilogram of BOD5 saved
represents a savings of up to 10 cents on treatment cost and 70 cents in
cost value of raw milk. (Grade A milk at a farm price of $7 per 100
Ib.) For a 227,000 kg/day (500,000 Ib) milk plant, this would represent
a potential return of $400/day or $120,000/year (based on 300 processing
days) .
Waste Reduction Through Engineering
Assignment of values to water and waste reduction through engineering is
very difficult because of the mutiplicty of variable factors that are
involved. The values arrived at in this report are based on subjective
judgment. It is assumed that an overall reduction of about 2 kg
BOD5/kkg cf milk equivalent processed is achievable in a well^managed
plant through the application of presently available equipment,
processes and systems. The values used as a base line for unit
operations are the "standard manufacturing process; waste loads based on
"good management," reported in the 1971 Kearney report. it should be
recognized that these values were obtained on relatively limited data
and may net be generally achievable in the dairy industry as a whole at
the present time.
71
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An example of what can be achieved through application of engineering is
shown in Figures 14 and 15. Figure 14 shows the waste load for a fluid
milk operation under normal practices of relatively good mangement.
Figure 15 shows the values for unit operations and the plant after the
following engineering changes:
Installation of drip shields en all fillers.
A central water heating system with shut-off valves on all hoses
A product recovery for the HTST operation for start-up, change-
over, and shut-down.
Air blown down of lines.
A rinse recovery system.
- Collection of CIP separator sludge as solid waste?.
Utilization of all returns for hog feed.
Utilization of a water-tight container for all daimaged packaged
products.
The reductions achieved would appear to be as great as could be
conceivably possible under any currently available engineering equipment
process or systems.
The estimated reduction of waste water volume and EOD5 concentration for
the various engineering aspects cited in this report are summarized in
Table 15 along with the various suggested improvements in equipment
processes and systems. In seme cases it is not possible to estimate a
potential waste reduction in value. In many instances the systems are
being installed to eliminate dependence upon pecple and therefore
savings relate to management aspects of the plant operation. As in the
case of waste control through management improvement, the extent of
decrease in overall waste leads would depend to a large extent upon the
current utiliztion of recommended equipment processing systems. It must
be emphasized that the incorporation of engineering improvements without
concomitant management control can and has resulted in water and waste
discharges that are in excess of those of the dairy plant with less
modern equipment but planned management waste control.
The data in Table 15 must be considered as engineering judgement values
subject tc confirmation through additional analyses that are not
available at the present time.
In a well-operated dairy plant one of the most visible sources of
organic waste is the start-up and shut-down of the pasteurizing unit.
In this rspect, the utilization of a product recovery system merits
72
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Table 15
Effect of Enqineering Improvement of
Equipment, Processes and Systems on Waste Reduction
Engineering
Improvement
Eguijoment
Cone-type silo
Tank
Water Shut Off
Valves
Estimated Waste Reduction Potential
Water EOD
760 1 (200 gal.) 73 kg (160 Ib)
Up to 50% of water
used
Drain Screens
None
Crip, Saver
Filler Drip
Shield
Interlock
Control
None
Require water
for operation
Variable; water
saved equivalent
to about 10 1/1
about 10 1 (10 gal/
gal) cf product
Variable
Not estimable
waste represents
spillage in most
cases
0.3 kg per 38 liter
can (0.8 Ib/ 10 gal.
1.5 kg per 38 liter
can (3.2 lb/10 gal.
can) for heavy cream
Variable - can save
up to 0.25 kg BOD5/
kkg (0.25 lb/1000 Ib)
of milk packaged; 1.0 kg
BOD5/kkg (1.0 lb/1000 Ib)
of cream packaged. In
cases of poor management
and maintenance,
reduction could be
2 to 3 times these
values.
Not calulable. Loss
without control would
be caused only by
employee error. Such
error could result in
discharge of 1 kg BOD5
per kkg (1 lb/1000 Ib)
of milk processed, or
4 kg EOD5 per kkg
75
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(U lb/1000 Ib) of
heavy cream processed.
Engineering
Improvement
Eguip_ment
Ice Cream Filler
Drip Shields
Estimated Waste Reduction Potential
Water POD
Novelty Collection
System
Product Recovery
Can System
"Non-Leak"
Portable Damaged
Package Unit
Curd Saving
Unit
Variable - up to
20 1 per
liter (20 gal/gal)
ice cream saved
Variable - up
to 1,900 liters
500 gallons) of
water to wash
frozen novelties
down the drain
Variable; should
save 8.3 1 (2.2 gal)
of water per kkg
(2200 Ib) of milk
processed
Variable
Variable. At 6,800
1/hr, a one-minute
spill is equivalent
to 113 1 (30 gal)
of ice cream, 57 ka
(125.a Ib) of ice
cream, or 23 kg
(50.6 Ib) of BOD5
Variable - reduction
in loss depends on
efficiency of machine
On an average machine
savings should average
5-10 kg (11-22 Ib)
BOD/day.
Variable: Depends
on machine jams.
On an average
operation, should
save 0.1 kg
EOD5 per kkg (0. 1
lb/1000 Ib) milk
processed.
Variable; Depends on
machine jams. Should
save 0.1 kg BOD5 per kkg
(0.1 lb/1000 Ib)
of milk processed
Not calculable at
present time.
76
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Filler-Product
Recovery System
Engineering
Improvement
EguijDment
Case Washer
Control
HTST Recovery
System
Product Rinse
Recovery
Post Rinse
Utilization
Variable: probably
save 0.05 kg/kkg
BOD5 (0.05 lb/1000 Ib)
processed.
Estimated Waste Reduction Potential
Water BOD
Sy_stgms
CIP Systems -
Re-use Type
CIP Systems -
Single Use
Automated Continous
Processing
Should reduce water
used about 170 1/kkg
(20 gal/1000 Ib)
milk packaged
10% over single use
None (10% less
cleaning compound
under average use)
Save 300 liters (80
gal) water on each
product change over
6 change overs=
(1800 1 480 gal)
600 1 (160 gal)
water/day
About 2 liters
of water/kg (1 qt/
Ib) milk recovered
Approximately 5%
None
20% over hand-cleaning
20% over hand-cleaning
Save 0.6 kg BOD5/kkg
(0.6 lb/1000 Ib)
milk processed
for each product
change over. Change over =
910 kg/2 min x 6 =
5,460 kg (or 2002 lb/2 min x
6 = 12,011 Ib) = 3.3 kg (7.26 Ib)
BOD5 saved per day.
0.6 kg/kkg
(0.6 lb/100 Ib)
processed
milk
0.15 kg BOD/kkg (0.15 lb/1000 Ib)
milk processed
None
77
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(5,000 gallon of water volume
tanks, valves, of plant
pipes 8 controller)
Air Blowdcwn 0.1 kg water/kkg 0.2 kg BOD/kkg
(0.1 lb/1000 Ib) (0.2 lb/1000 Ib)
of milk processed of milk processed
Engineering Estimated Waste Reduction Potential
Improvement Water BOD
Ice Cream Ferun
System 2 1/1 (2gal/gal) Variable; in most
ice cream saved operations, saving
(spilled ice cream in BOD5_ should average
is rinsed to drain) 245 kg (540 Ib) BOD5/day.
78
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particular mention in terms of potential waste savings. Figure 16 shows
the fat losses and product loss as a function of time during the start-
up and shut-down of a 27,300 kg/hour (60,000 Ib/hour) high temperature
short-time pasteurizer. To go from complete water to complete milk or
from complete milk to complete water generally requires approximately
two minutes with the discharge of approximately 910 kg (2,000 Ib) of
product and water every time the unit is started, stopped,or changed
over in water between products. The utilization of the product recovery
system for HIST units can result in a 75% reduction in product going to
drain.
End-of-Pi£e_Waste_Treatment_Technolo5_y
The discussion that follows covers the technologies that can be applied
to raw waste from dairy manufacturing operations to further reduce waste
leads prior to discharge to lakes or streams. The subjects covered
include current treatment practices in the industry, the range of
technologies available, problems associated with treatment of dairy
wastes, and the waste reductions achievable with treatment.
Current Practices
Dairy wastes are generally amenable to biological breakdown.
Consequently, the standard practice to reduce oxygen demanding materials
in dairy waste water has been to use secondary or biolcgical treatment.
Tertiary treatment practices in the dairy industry - sand filtration,
carbon adsorption, or other methods - are almost nil. Systems currently
used to treat dairy waste water include:
Activated Sludge
In activated sludge systems the waste water is brought into contact with
microorganisms in a aeration chamber where thorough mixing and provision
of the oxygen required by the concentrated population of organisms are
accomplished by use of aerators. Aerations chambers are designed with
sufficient capacity to provide a theoretical retention time that may
vary with the concentration of the waste but is generally on the order
of 36 hours. The discharge from the aeration chamber passes to a
clarifier where -the microorganisms are allowed to settle as a sludge
under quiescent conditions. Most of the sludge is returned to the
aeration chamber to maintain the desired concentration of organisms and
the remainder is wasted, generally as a solid waste following
dewatering. The supernatant liquid may be discharged as a final
effluent or subjected to additional treatment such as "polishing" (e.g.,
filtration) or chlorination.
Trickling Filters
In trickling filters the waste water is sprayed uniformly on the
surface of a filter composed of rock, slag or plastic media, and as it
79
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trickles through the filter the organic matter is broken down ty an
encrusting biological slime. Conventional rock or slag beds are 1.8 to
2.4 meters (6 to 8 feet) deep. Plastic filters are built taller and
occupy less area. As the waste passes through the filter some of the
slime sloughs and is carried away, thus allowing continued exposure of a
surface of active young biota and preventing clogging of the filter by
excessive slime growth. Sloughed slime generally is settled, dewatered
and disposed of as a solid waste. In the operation of most trickling
filters a major portion (up to 95 percent) of the filtrate is recycled
to increase efficiency of organic waste removal and assure proper
wetting of the filter.
Aerated Lagoons
Aerated lagoons are similar in principle to activated sludge systems
except that there is generally nc return of sludge. Hence, the
microbial population in the aerated basin is less than in activated
sludge tanks and retention of waste water must be longer to attain high
BOD5 reduction. A settling lagoon usually follows the aerated lagoon to
allow settling of suspended solids. Mixing intensities are usually not
as great as in activated sludge tanks. This results in a suspended
solids blanket covering the aerated and settling lagoons which is
further attacked by aerobic and anaerobic bacteria. Periodically the
sludge blanket has to be dredged out. A clarifier may be used between
the first and second stage lagoons with the settled sludge returned to
the first stage. This both reduces the sludge to be dredged from the
second stage and improves the effiency of the first stage by increasing
the density of microorganisms.
Stabilization Ponds
Stabilization ponds are holding lagoons, 0.6 to 1.5m (2 to 5 ft.) deep,
where organic matter is bicdegraded by aerobic and anaerobic bacteria.
Algae utilize sun rays and C02 released by bacteria to produce oxygen
which in return allows aerobic bacteria to breakdown the organic matter.
In lower layers, facultative or anaerobic bacteria further biodegrade
the sludge blanket.
Disposal Cn Land
Disposal on land of waste waters is an alternative which deserves
careful consideration by small operations with a rural location. Land
reguirements are relatively large, but capital costs and operational
costs are low. Typical procedures are:
1. Spray Irrigation - This consists of pumping and discharging the
wastes over a large land area through system of pipes and spray
nozzles. The wastes should be sprayed over grasses or crops to
avoid erosion of the soil by the impact of the water droplets.
Successful application depends on the soil characteristic -
81
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coarse, open-type soils are preferred to clay-type soils - the
hydraulic load, and EOD5 concentration. A rate of application
of 56 cu m/ha per day (6,000 gal/ac per day) is considered
typical.
2. Ridge and Furrow Irrigation - The disposal of dairy wastes by
ridge and furrow irrigation has been successfully used by small
plants with limited volume of wastes. The furrows are 30 to 90
centimeters (1 to 3 ft) deep, and 30 to 90 centimeters (1 to 3
ft) wide, spaced 0.9 to 4.6 m (3 to 15 ft) apart. Distribution
tc the furrows is usually from a header ditch. Gates are used
tc control the liquid depth in the furrow. To prevent soil
erosion and failure of the banks, a good cover of grass must be
maintained. Odors can be expected in warm weather, and in cold
weather the ground will not accept the same volume of flow.
The need to remove the sludge which accumulates in the ditches
is an additional problem which does not exist in spray
irrigation.
3. Irrigation by Truck - The use of tank trucks for hauling and
disposing of wastes on land is a satisfactory method for many
dairy food plants. However, the cost of hauling generally
limits the use of this method to very small plants. Disposal
on the land may be done by driving the tank truck across the
field and spraying from the rear, or by discharging to shallow
furrcws spaced a reasonable distance apart.
Anaerobic Digestion
Anaerobic digestion has been practiced in small dairies through the use
of septic tanks. In the absence of air, anaerobic bacteria breakdown
organic matter into acids then into methane and CO2. Usually a
reduction period of over three days is required.
Combined Systems
Waste treatment plants combining the features of some of the biological
systems described in the preceding paragraphs have been constructed in
some dairy plants in an attempt to assure high BOD5 reduction
efficiencies at all times. Examples and possibilities of such systems
include: An activitated sludge system followed by an aerated lagoon;
trickling filter followed by activated sludge system; activated sludge
system followed by sand filtration.
Eegign Characteristics
Figure 17 is a schematic flow diagram of activated sludge, trickling
filter and aerated lagoons systems which should perform satisfactorily.
Table 16 lists the recommended design parameters for the three types of
biological treatment systems. Systems constructed in accordance with
82
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FIGURE 17
RECOMMENDED TREATMENT SYSTEMS
FOR DAIRY WAstEWATER
ACTIVATED SLUDGE SYSTEM
TRICKLING FILTER SYSTEM
AERATED LAGOON SYSTEM
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the suggested design characteristics should result in year-round EOD5
reductions above 90 percent.
It is recognized that biological waste treatment facilities do not
operate at constant efficiencies. Very wide variations of the ECD5
reduction efficiencies from day to day and throughout the year can be
expected frcm any individual system. Factors such as EOD5
concentration, type of waste, flow, temperature, and inorganic
constituents of the effluent may affect the rate cf treatment of dairy
wastes by living organisms, but the interaction of and correlation
between such factors is not fully understood. Available data show that
it is possible to achieve BOD5 reduction efficiencies greater than 99%
part of the time with almost any of the types of biological waste
treatment that are available. However, due to high variability of the
composition of dairy effluents these same treatment systems can have
EOD5 reduction efficiencies as low as 30% during other times, such as
after sudden, highly concentrated leads are discharged or other causes
if severe upset occurs.
To obtain consistent high BOD5 removal, it is essential to allow
microorganisms to bicdegrade organic matter under favorable operating
conditions. These include properly designed and operated treatment
systems tc prevent shock loads and to allow microorganisms to function
under well balanced conditions; addition of nutrients if absent;
exclusion cf whey and cheese washes; in-plant reduction of waste water
BOD5 to a minimum; and maintaining favorable temperature levels and pH
when ever possible.
Research indicates that percent EOD5 removal decreases with increasing
EOB5 influent concentration. In one experiment, the BOD5 reduction
efficiency of an activated sludge system decreased significantly when
influent BOD5 concentration increased beyond 2,000 mg/1. High EOD5
loading (in excess of 2000 mg/1) decreased the concentration of gram
negative organisms and encouraged the development of a microflora that
apparently could not utilize animo acids as a nitrogen source, but only
inorganic nitrogen, such as ammonia nitrogen. Under these conditions
the efficiency of the system decreased.
Detergents at concentrations above 15 mg/1 begin to inhibit microbial
respiration, with anionic detergents showing relatively less inhibitory
effects than non-ionic and cat ionic surfactants.
Treatment_cf_Whey_
Whey constitutes the most difficult problem facing the dairy industry in
respect tc meeting effluent guidelines in two respects: (a) the supply
of whey generally exceeds its market potential at the present time and
(b) whey is difficult to threat by any of the common biological
85
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treatment irethods. Generalization about whey handling and treatment can
easily be rrisinterpreted. In no other instances is the fact more clear
than with whey that each individual circumstance must be evaluated in
light of the particular situation existing at the particular plant. The
type of whey, accessibility tc an existing whey processing facility,
volume of whey produced, location of the plant, and the type of farm
operations contingent to the processing facility are among the few of
the factors which must be taken into consideration in determining
disposition cf whey for a particular plant situation.
If whey is to be processed further for feed or food, a major factor in
the handling of such whey is to prevent the development of further
acidity in the product after manufacture. This is true of cottage
cheese whey was well as sweet whey. It is a well recognized fact that
the development of acidity in the product increases the diffiucly of
drying the product. This effects is particularly well illustrated by
the recent article by Pallansch (Proceedings Whey Products Conference,
1972) shewing the temperature at which sticking occurred as a function
of lactic acid content. Cottage cheese whey, which has long teen
recognized to be more difficult to dry than rennet whey, becomes
impossible tc dry at pH below U.2 in most equipment.
Prevention of development of acidity and outgrowth of undersirable
spoilage cr potential pathogens requires that whey be cooled to about
UO°F and maintained at this temperature until processed. Whereas this
can generally be achieved in most plants where processing is conducted
in the same plant as the whey is produced, lack of adequate cooling
equipment in many small plants will require a considerable expenditure
on the part of these plants tc cool the whey. This becomes particularly
a problem in respect to the shipment of whey over long distances both in
respect to preceding and in recooling at the point of receipt. Another
problem related to this general area is a lack of a really adequate
procedure for concentrating the product at the point of manufacture in
an economical manner. Membrane processing procedures are fine in
principle and are approaching possible application. There remains the
problem of sanitation that still is a limiting factor for almost all
current membrane processing systems now on the market. In almost all
cases further improvement in sanitation design is going to be required
to make these pieces of equipment fully adequate for concentration of
whey that is going to be subsequently used for food or feed. This is
especially true in respect ot possible fluid uses.
Whey for food use must be considered in an identical manner as Grade A
milk from a micrological viewpoint, and cannot be handled as a by-
product. It is particularly a point for food use that whey be cooled
and maintained at 40° from the time of manufacture until final
processing to avoid the outgrowth of undesirable organisms. Alterations
in the product due to residual proteases from the coagulant might
develop into further acidity, and potential development of food
poisoning organisms.
86
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From a processing point of view there are a number of procedures that
are potentially available to the whey manfacturers. However, at this
point in time the only really proven method of processing whey is its
concentration and drying for fcod or feed use. The market potential for
whey is tied very closely to the availability and price of skim milk
powder on the commercial market. Several large scale whey drying plants
have had tc either shut down or to convert from food grade to feed grade
powder as a result of increased importation of milk powder.
Alternatives in the Dispostion of Whey
The following are some of the more common methods of disposing of whey
at the present time:
return to farmers suEEiYiQS £*}§. milk as feedj_ This
approach is limited to very small plants whose suppliers are in the
immediate locality of the plant and are engaged in livestock
feeding. Whey generally can be fed at levels of up to 50%
substitution without creating scours or other problems even in
ruminant animals. Frequently lack of acceptability of whey as a
feed tc ruminants creates problems.
2- §EI§Y iEri3§ticrK Where feasible the best method of treatment
of whey is through spray irrigation. Because of the low loading
required for adequate spray irrigation, the approach is limited to
plants that are located in rural areas with adequate land and
generally limited to relatively small plants. Plants producing
cottage cheese whey in excess of 100,000 Ib who previously had
utilized this method of disposal have been forced to desist from the
use of spray irrigation in such states at Vermon, New York, and
Ohio. The freezing of the ground surface in northern climates and
the run-cff in thawing has been a major reason for closing down
large scale spray irrigation systems in the northern states.
to municipal treatment sy_stems^ For plants located in
large municipalities, where the contribution of EOD5 to the total
plant load is low (less than 10%) joint treatment is a feasible
method cf treatment without interference with the efficiency of the
municipal system, provided that shock loading is avoided. The
installation of equalization tanks is generally required by the
municipality. In a few instances it has been found desirable to
cool the whey to prevent further acid production to facilitate its
biological oxidation.
5. Concentrating and dryjLngj, At the present time this appears to
be the most feasible procedure for the utilization of whey as a food
or feed. In 1971 in the State of Wisconsin about 90% of all sweet
whey was handled in this manner. Problems associated are the
frequent necessity to haul non-concentrated whey long distances,
87
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lack cf an adequate market for the finished product, and large
capital expenditure for the concentrating and drying equipment.
6- !i§£££2£li^iY§i§i Tne electrodialysis process provides a product
of high quality for special pharmaceutical applications, but the
process is well covered by proprietory patent and the direct market
is limited.
7. Ultraf_iltration and reverse osmosis^ While potentially a very
promising development, especially for the recovery of a potentially
marketable protein product, current commercialization of this
process to its full potential is dependent upon more complete
development of sanitary membrane processing equipment as cited
earlier. New developments in sanitation and cleaning procedures
plus development of operations that operate under lower fouling
conditions lends possible promise for commercialization in the
immediate future. At the present time it is much easier to sanitize
ultrafiltration than reverse osmosis equipment.
8. Concentration and Plating for f_eed application^ The utilization
of filir evaporators originally developed by the cirtus industry
followed by plating of the concentrate on bran or citrus pulp may be
a relatively low cost potential in development of an improved
quality feed stuff. The competitive position of such a product
depends upon the future economic situation in the feed grains,
especially corn and soybeans.
9. Protein concentrates^ In addition to ultrafiltration, various
procedures for the preparation of protein concentrate including
polyphcsphate percipitation, iron product precipitation, CMC co-
precipitation and gel filtration are all potential methods which
remain unproven as viable commercial entities at the present time.
The full commercialization of these procedures awaits the
development of a better market for the protein product. The market
for protein product is ironically limited at the present time
because of inadequacies in economics of procedures for providing
high quality protein. The greatest potential application,
fortification of soft drinks, requires large quantities of whey
protein that cannot be supplied at present. Therefore, soft drink
manufacturers hesitate to enter the field, whey manfacturers
hesitate to develop the processes, so that at the present tiire we
have somewhat of a standoff in this area.
10. lerjnentation froducts^ The utilization of whey as a media for
the production of yeast cells as a feed and potential food product
is under commercialization at the present time. At this point there
are nc data indicating the relative economics of this process in
respect tc drying. The major use for the end product at the current
time is feed, and again the market potential depends upon the
comparative costs of other feed supplements and feed products
88
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including corn and soybeans. The spent liquor from the fermentation
does constitute a potentially difficult disposal problem at the
present time. We have inadequate information in this area.
11. Lactose modification^ Numerous investigators are currently
studying the possibility of hydrolyzing lactose in whey by soluble
and by immobilized enzymes. The overall development of this field
is at least several years behind that of membrane processing and its
success also will depend upon the solving of microbiological and
sanitation aspects of the process. In addition drying of lactose
modified whey becomes more difficult because of the increased
colligative property of the product and increased stickiness at the
same acidity.
12. Lactose^ A limited market for lactose is the major factor in
the full utilization of this material at the present time. Much
research is being done but a clear solution to the problem is not
yet in sight. A solution to the the lactose utilization problem is
of major concern. Even processes that recover valuable products in
the fcrm cf whey protein result in residuals containing 80% as much
BOD5 as the original whey because of the lactose. Methylation,
phosphcrylaticn, polymerization are laboratory possibilities at the
present time. However, until the market is developed for the
finished product, commercialization of such technologies appears to
be improbable and at the best uncertain.
Problems Associated With the Biological Oxidation of Wheyj.
Lagoons, trickling filters, and activated sludge systems are all upset
by the incorporation of whey into the waste water.
Dairy plants manufacturing whey that operate their own treatment
facilities have recognized for a long time the desirability of keeping
whey out cf the treatment system. The reason for problems with the
biological oxidation of whey has been given as a BOD:N ratio that is
undersirable and that whey is deficient in nitrogen. The BOD:N ratio,
however, is near to 20:1, a value considered to be satisfactory. Two
recent studies in the Ohio State University laboratories have some
possible bearing on the problem of whey treatment.
1. High BOD5 loading (in excess of 2000 mg/1 BOD) decreases the
concentration of gram negative organisms and encourages the
development of. a microflora that cannot utilize amino acides as a
nitrogen source. The micrcflora that exist under high EOD5 loading
can use only inorganic nitrogen, such as ammonia nitrogen. Under
these conditions the efficiency of the system decreases.
2. The constituents present in the highest concentration in milk
wastes is lactose, and nearly all of the lactose ( 80%) in milk is
present in whey. The first step in the degradation of lactose is:
89
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lactase
lactcse - > glucose + galactose
During the manufacture of cheese, a small amount of the lactose is
degraded to glucose and galactose. Glucose is readily utilized by the
bacteria tc product lactic acid, but galactose is not as readily
degraded. Studies in the Ohio State University laboratory have shown
that whey contains about 0.05* glucose and 0.3-0.45% galactose.
Galactose is about 20 times more effective as an inhibitor of lactase
than lactcse is as a substrate. Galactose at a concentration of O.U%
will inhibit lactase by more than 50%. At the same time there is some
evidence, which needs further confirmation, that galactose also stops
the organisms in the biomass from producing any more lactase enzyme.
Studies are needed under commercial conditions to confirm these
findings.
If substantiated, methods could be developed to materially increase the
efficiency cf biological treatment of . dairy wastes and permit the
development of procedures to treat whey.
Studies are in progress under the auspices of the National Science
Foundation to determine if lactase treatment of milk wastes will improve
their treatability. Laboratory studies have been completed under this
grant to prove that the addition of gram negative organisms to an
activated sludge treatment system permits removal of up to 98% BOD5 at a
EOD5 loading of 3000 mg/1. (Only about 80% reduction was possible in
the absence of the organisms.) The organisms must be added on a regular
basis, since they cannot compete with the gram positive organisms in the
system. (A field study has shewn that a treatment system for a one
million pound milk-cottage cheese plant was materially improved by the
bi-weekly addition of gram negative organisms. The EOD5 reduction was
increased frcm 85 to 96%; sludge age was decreased; sludge volume
decreased by 40%; and the mixed liquor VSS were increased from 1500 to
5000 mg/1.
Adyajit age s_AiQd_Cisadvantages_Oj_Various_SY stems
The relative advantages, disadvantages and problems of the waste water
treatment irethods utilized in the dairy industry are summarized in Table
17.
Management^Cf
If biological treatment systems are to operate satifactorily, they must
not only be adequately designed, but must also be operated under
qualified supervision and maintenance. Following are some key points
that should be observed to help maintain a high level of performance.
90
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91
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(a) Suggestions Applicable To All Biological Systems
1. Exclude all whey frcm the treatment system and the first wash
water from cottage cheese.
2. If it is impossible to exclude whey from the treatment system,
a retention tank should be provided so that the whey can be
metered into the treatment system over a 24-hour period. In
this case it would be necessary to make sure that the pH of the
whey does not fall below 6.0. Normally, this would require a
neutralization process.
3. It would be beneficial to provide pre-aeration for all dairy
feed plant wastes.
4. A retention tank of sufficient size should be provided to hold
the waste water from one processing day to equalize hydraulic
and EOD5 loading. Such an equalizing tank might well be pre-
aerated.
5. The treatment facility should be under the direct supervision
of a properly trained employee. He should have sufficient time
and sufficient training to keep the system in a total operating
condition. It should be recognized that in the operation of a
dairy food treatment plant there are two types of variations
that cause operating problems. The first of these are the
short term surges from accidental spillages that can be
disastrous to a treatment facility if not checked immediately.
In the hands of a skilled operator, immediate corrective
measures can be taken. The second type is much more difficult
to control and relates to the very slow acclimatization of the
biological microflora to dairy food plant wastes. This appears
to take a minimum of about 30 days so that changes in the
composition of the waste may not show up in changes in
operating characteristics of the treatment system for 30 to 60
days.
6. The operating personnel should keep daily records and operate a
.routine daily testing procedure which should include as a
minimum; influent and effluent pH, influent and effluent BOD,
influent and effluent suspended solids, calculation of BOD5 and
hydraulic loading, and a log of observations on the operation
of the treatment facility.
7. The dairy food plant should be operated in such a manner as to
minimuze hydraulic and BOD5 shock loading.
8. Any accidental spillage in the dairy food plant should be
immediately indicated to the engineer in charge of the
treatment facility. This is particularly critical if there is
92
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inadequate equalization capacity ahead of the treatment
facility.
9. All equipment should te kept in good operating condition.
10. Final treatment effluent may need to be chlorinated and checked
fcr coliform organisms.
11. In the development stages of planning a new treatment facility
or an expanded treatment facility, lab or pilot scale operation
of the design type should be made for at least 60 days in the
intended loading and process region.
(b) Recommendations in Respect to Spray Irrigation
1. Spray irrigation is generally not practical in dairy plants
processing over 100,000 pounds of milk per day or discharging
over 0.5 pounds of BOC5 per thousand pounds of milk processed.
2. Regular inspection of the soil should be made to evaluate
organic matter and microbial cell build-up in the soil that
could lead to "clogging".
3. The land used for spraying should be rotated to minimize over-
loading of the soil.
4. Regular inspection of the spray devices should be made to
eliminate clogging and uneven soil distribution over the land
surface.
5. A drain area should be located on the low side of the
irrigation field and the run-off checked on a regular basis to
determine the efficiency of the operation. If the irrigation
field is adjacent to a stream, then regular monitoring of the
stream should be made to insure adequate operation, since it is
insufficient to assume that spray irrigation is 100% effective.
(c) Suggestions Concerning Oxidation Ponds
1. Aerated lagoons have limited application in areas where they
are frozen for a period of time during the winter.
2. Normal loading of aerated lagoons is 2 pounds of BOD5 per day
per 1000 ft3 for ponds with a 30-day retention time. This
level of loading appears to provide an optimum ratio of
micrcbial and algal balance in the ponds.
3. Diffusers should be regularly inspected to insure that inlets
are not clogged.
93
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4. Dissolved oxygen should be measured regularly in the first and
second aeration ponds and correlated to the loading and to the
air input to the lagoon.
(d) Suggestions in Respect to Trickling Filter Systems
1. The system should be loaded between 17 and 20 Ib BODjj per
thousand cu ft with a recirculation ratio of from 8 to 10.
2. In northern climates, the filter should be enclosed or
otherwise protected for year-round operation.
3. The flow to the filter should run for 24 hours out of every 24-
hour day.
4. All debris and solids should be prefiltered.
5. Inspection of the distribution system of the filter should be
made regularly to insure a uniform distribution of the
influent.
6. Pre-aeration is useful in the treatment of wastes by trickling
filter procedures. Where blowers are used, they should have a
capacity of 0.5 cu ft/gal of raw waste treated.
7. Filters should be inspected regularly for ponding. If ponding
occurs, it may be desirable to decrease hydraulic flow and
flush the filter with high pressure hoses.
(e) Suggestions with Relationship to the Operation of an Activated
Sludge Treatment System
1. The operator should have dissolved oxygen data available in the
pre-aeration and assimilation tanks. It would be desirable to
have the measuring equipment integrated into the oxygenating
equipment to serve as a controlling device. Frequently,
problems in respect to dairy food plant activiated sludge
treatment systems result from lack of close attention to trends
in the system, and operation is always in reaction to changes
that have already taken place. In the case of Type-2 (stable)
foam, the operator frequently will cut the air level back to
decrease the foam only to have the treatment system go
anaerobic. Abrupt changes in aeration are to be avoided to
prevent sharp changes in operating characteristics. One of the
most difficult factors to control in dairy food plant waste
activated sludge systems is proper aeration.
2. The operator should make regular inspection of the aerating
devices to make sure that there is no clogging of the inlets.
94
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3. There should be intentional sludge wastage, especially in the
case of extended aeration type activated sludge treatment. The
amount of wastage may be varied depending upon the
characteristics of the sludge. One of the most serious
problems in dairy food plant activated sludge treatment is the
pcor characteristics of the sludge formed. The reasons for
poor sludge characteristics relate in part to the chemical
nature of the waste, the microbial flora and the operating
characteristics. The problem is highly complex and step-wise
procedures for control or correction of the problem have not
yet teen developed.
*». The loading of the treatment plant should be in the range of
0.2 to 0.5 Ib BOD/lb mixed liquor volatile suspended solids
(MLVSS), and in the range of 35 to 50 Ib EOE5 per thousand cu
ft.
Tertiary^Treatment
Even at EOD5 reduction efficiency above 90%, biological treatment
systems will generally discharge BOD5 and suspended solids at
concentrations above 20 mg/1 (see Table 18). For further reduction of
EOE, suspended solids, and other parameters, tertiary treatment systems
may have to be added after the biological systems. To achieve zero
discharge, systems such as reverse osmosis and ion exchange would have
to be used to reduce inorganic and organic solids that are not affected
by the biological process.
The following is a brief description of various tertiary treatment
systems that could have application in aiming at total recycling of
dairy waste water.
Sand Filtration involves the passage of water through a packed bed of
sand on gravel where the suspended solids are removed from the water by
filling the bed interstices. When the pressure drop across the bed
reaches a partial limiting value, the bed is taken out of service and
backwashed to release entrapped suspended particles. To increase solids
and colloidal removal, chemicals are added ahead of the sand filter.
Activated Carbon Adsorption is a process wherein trace organics present
in waste water are adsorbed physically into the pores of the carbon.
After the surface is saturated, the granular carbon is regenerated for
reuse by thermal combustion. The organics are oxidized and released as
gases off the surface pores. Activated carbon adsorption is ideal for
removal of refractory organics and color from biological effluent.
Lime Precipitation Clarification process is primarily used for removal
of soluble phosphates by precipitating the phosphate with the calcium of
lime to produce insoluable calcium phosphate. It may be postulated that
orthophosphates are precipitated as calcium phosphate, and
95
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96
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pclyphcsphates are removed primarily by adsorption on calcium floe.
Lime is added usually as a slurry (10^-15% solution), rapidly mixed by
flocculating paddles to enhance the size of the floe, then allowed to
settle as sludge. Besides precipitation of soluble phosphates,
suspended solids and collodial materials are also removed, resulting in
a reduction of BOD, COC and other associated matter.
With treated sewage waste having a phosphorus content of 2 to 8 mg/1,
lime dosages of approximately 200 to 500 mg/1, as CaO, reduced
phosphorus content to about 0.5 mg/1.
Ion-Exchange operates on the principle of exchanging specific anions and
cations in the waste water with nonpollutant ions on the resin bed.
After exhaustion, the resin is regenerated for reuse by passing through
it a solution having the ion removed by waste water. Ion-exchange is
used primarily for recovery of valuable constituents and to reduce
specific inorganic salt concentration.
Eeverse Osmosis process is based on the principle of applying a pressure
greater than the osmotic pressure level to force water solvents through
a suitable membrane. Under these conditions, water with a small amount
of dissolved solids passes through the membrane. Since reverse osmosis
removes organic matter, viruses, and bacteria, and lowers dissolved
inorganic solids levels, application of this process for total water
recycles has very attractive prospects.
Ammonia Air Stripping involves spraying waste water down a column with
enforced air blowing upwards. The air strips the relatively volatile
ammonia from the water. Ammonia air stripping works more efficiently at
high pH levels and during hot weather conditions.
Recycling System
Figure 18 gives a schematic diagram of a teriary treatment system that
could be used for treatment of secondary waste water for complete
recycle.
For recycling of treated waste water, ammonia has no effect on steel but
is extremely corrosive to copper in the presence of a few parts per
billion of oxygen. Ammonia air-stripping and ion-exchange are presently
viewed as the most promising processes for removing ammonia nitrogen
from water.
Besides the secondary biological sludge, excess sludge from the tertiary
systems—specifically the lime precipitation clarification process--
viould have to be disposed of. Sludge from sand filtering backwash is
recycled back to biological system. Organic particles, entrapped in the
activated carbon pores, are combusted in the carbon regenerating
hearths.
97
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98
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Pretreatment of Dairy Viaste Discharged
To_Munici£al_Sanitar^_Sewers
General
Eairy waste water, in contrast to many other industrial waste waters,
does not contain quantities of readily settleable suspended solids and
is generally near neutral. Hence, primary treatment practices such as
sedimentation and neutralization have no necessary application in the
case of dairy waste water. Equalization is recommended for activated
sludge and trickling filter systems; however, dairy waste loads
discharged to municpal treatment plants will be equalized in the sewer
lines if the dairy waste water does not constitute a very large
proportion of the load on the municipal plant.
The best approach to reduce the load on municipal plants and excessive
surcharges is good in-plant control to reduce BODJ5 and recycling of
cooling water.
However, if sanitary districts impose ordinances which can be met only
through scrre degree of pretreatment, the following treatment methods are
suggested:
1. Anaerobic digestion.
2. High-rate trickling filters and activated
sludge systems.
3. Stabilization ponds.
4. Aerated ponds
5. Chemical treatment
Anaerobic digestion could be applicable to small plants discharging low
volume waste. High-rate trickling filters and activated sludge systems
require high capital outlay and have appreciable operating costs.
Stabilization ponds and aerated ponds require considerable land and will
usually be impractical for dairy plants located in cites. Chemical
treatment will require a high capital outlay and an extremely high
operating costs, especially with sludge disposal. In regard to
efficiency, anaeorbic digestion and stabilization ponds will attain less
EOD5 reduction. However they could eliminate appreciable BOD5 at very
long retention periods.
If the dairy waste is a significant part of the total load being treated
by a municipal plant, it is necessary that whey be segregated to avoid
the risk cf upsetting the system.
Hexane Solubles
99
-------
Seme municipalities across the country are imposing tight restrictions
on hexane soluble fats, oils and grease. Waste containing mineral cils
discharged by the cherrical and petrochemical industries and other
sources inhibit the respiration of microorganisms. However, fat in
dairy waste water does not exhibit such an inhibitory effect.
Appreciable quantities of dairy fat are being treated successfully
biologically with no noticeable effects on microorganisms (see Table
19).
Although large quantities of floating fats and grease could potentially
clog or stick to the walls of sewer lines, dairy fat does not contain
inhibitory substances or toxic heavy metals that could upset a municipal
treatment system. Sanitary districts should recognize the difference
between the potential detrimental effects of mineral-based versus milk-
based fats, oils and grease in applying their ordinances. A test that
distinguishes betwee i those sources of fatty matter should be developed,
since mineral oil and dairy fat are both solubilized in the hexane test
currently used for control purposes.
Biological Treatment
Performance data for dairy treatment systems are presented in Table 20.
Two groups of data are shown: One from identified plant sources and the
other froir literature sources.
Activated sludge, trickling filter, and aerated lagoon data from a
limited number of identified plants indicated average BOD5 removals of
97.3%, 94. 0* and 96.2% respectively. Those treatment plants are, in
general, well designed, well managed facilities, or "exemplary" plants.
The overall average performance of these facilities is a BOD5 reduction
of 96. 1%. The overall average BOD5 reduction of 97 literature reported
plants is 91.9%. Four identified combined systems show an average EODJ5
reduction cf 95.7%.
Table 20 excludes all EOD5 reduction values below 70%, which were
reported in Kearnery's 1971 Dairy report. A system for refine treatment
functioning below 70% BOD5. reduction has been considered underdesigned
or ill-managed and does not reflect its actual capabilities. Anaerobic
digestion has a much lower efficiency (30.5% BOD5 reduction frcm two
data sources) but is a good preliminary buffering stage, especially for
low volume waste to be treated by activated sludge or trickling filter-
systems. Stabilization ponds also represent a good preliminay buffering
stage prior to activated sludge or trickling filter systems when land is
available.
One data source for sand filtration shewed average reductions of 81.0%
for BOD and 95.5% for suspended solids. Sand filtration removes not
100
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only suspended solids but also associated EOD, COD, turbidity, color,
bacteria and ether matter.
Tertiary Treatment
Table 21 gives a general comparison of tertiary treatment systems
efficiency to remove specific pollution parameters.
Table 22 gives some further insight of the efficiencies of tertiary
treatment systems. It shows reductions produced after passage of
biological effluent through sand filtration and activated carbon at the
South Tahce, California, treatment plant. The effluent from the
conventional activated sludge process is treated with alum and
pclyelectrclyte prior to its passage through a multi-media sand filter.
102
-------
Table20
Type of
Treatment
Activated
Sludge
Trickling
Filters
Aerated
lagoons
Average
Performance
Data
Plant
of Dairy Waste water Treatment Plants
from Literature
Sources (133)
Number Percent BOD5 Reduction
of Plant Averaqe Range
63
32
2
92.9 74-99.6
90.5 70-99.8
84^.5 70-98.0
21*2
Data from Verifiable
Plant Sources
Number Percent BOD5
of Plant Average
3 97.3
2 94.0
4 96.2
26-1
Reduction
Range
96.6-98.7
93.0-95.0
95.2-97.3
Stabilization
Ponds
Combined
Systems
Anerobic
Digestion
Sand
Filtration
1
None
None
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4 95.7
2 30.5
1 81.0
—
91.9-99.6
19.8-41.3
81.0
(of Secondary Effluent)
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105
-------
SECTION VIII
CQSTxENERGY_AND_NON^WATER_gUALITY_ASPECTS_
Cost_of_In-P1ant_Contro1
An accurate assessment of the costs of in-plant improvement is not
possible tecause of the following:
- bread variation in types and sizes of plants
- geographical differences in plant location
- difference among plants in respect to their current
implementation of necessary management and
engineering improvements
- management limitations
However, an estimate of costs is provided in this section for
engineering improvement areas. These values should be used as general
guidelines only; they could vary substantially in individual situations.
For the saire reasons indicated abover it is not possible to relate costs
incurred for in-plant control to specific reduction benefits achievable
(as estimated in Section VII) on an industry or subcategroy basis.
However, many of the in-plant improvements that have been suggested in
this report as means to achieve the effluent limitation guidelines have
been successfully implemented in a number of plants at a net economic
return as a result of product saved. It may be reasonably assumed,
therefore that the in-plant controls necessary to achieve the suggested
effluent guidelines in many plants will cost little or no more than
economic return they will achieve. Exceptional cases in all probability
will involve the economic disposal of whey in plants producing cottage
or natural cheese.
Cost of Equipment, Process and Systems Improvements
The costs involved in making the engineering improvements suggested in
Section VII are equally difficult to ascertain with precision, and
certainly will change with plant location, with size and type of plant,
and with the supplier of the equipment. Estimated values are based on
figures obtained from various major manufacturers of dairy plant
equipment, and are presented in Table 23. They should be considered as
guidelines values; the cost in individual situations could be as much as
2Q% higher than the quoted figures.
107
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Table 23
ESTIMATED COST OF ENGINEERING IMPROVEMENTS OF EQUIPMENT,
ANE SYSTEMS TO REDUCE WASTE.
Item ynii_Qost_ Total Cost for a
230,000 kg/day
(500,00 Ib/day)
dairy__p_lant
Standard_Ecjui]:n!ent
Automatic Water
Shut-Off Valves $15-25 $300
valve
Erain Screens $ 12 $150
(Note: Not recommended by equipment suppliers, because they plup-up
too easily. New design needed for drain. Quick estimate of non-fouling
drain system viould be $150/drain) .
Liquid Level Control $300/probe $6,000 (min)
Temperature Controller $1,000 $2,000
CIP Line Support $330/100m (Included in line
($100/100 ft.) installation cost
of $2500/valve)
Erip Saver (can
dumping) $150 (Not applicable)
Evaporator Improvement Included today in basic cost of equipment
Filler Dripshield $50-250 $1,500
(Cost depends on size
and type of filler)
(Drip shield Ncte: These items would have to be specially designed and
may cause redesign in filter.)
Evaporator Improvement Included today in basic cost of equipment
New_EguiErrent_Concepts
Ice Cream Filler $1,000 $3,000
108
-------
Item
e_23 (con'-t)
Unit cost
Total Cost fcr a
230,000 kg/day
(500,00 Ib/day
dairy__p_lant
Novelty Collection System
Case Washer
Water Control
Product Recovery Can
System (including 20
gallon container, piping,
fittings, and controls)
"Non-leak" Damaged Package
Unit; complete with pump
valve, level controller,
spray device.
Interlock control between
CIP and air blow down
Filler Product Recovery
System
CIP Fittings
and
Controls
Equipment manufacturers cannot
estimate cost at this time. Would
require special design.
$ 550
$2,000/unit
$2,500
$ 700
$2,700
$ 25-30/
fitting
$ 300-500/
control
$ 550
$6,000
$7,500
$U,200
$10^800
Improvement^of_SYStems__based_gn ExistingmComponents
CIP System
- Revised type
$10,000/
unit
$30,000
109
-------
Table_23 (con't)
Unit Cost
CIP System
-Single-Use type
BTST Receiving System
Air Blow Down System
Non-Lubricated
Air Compression
Air Blow Ecwn Unit
(filler, valve, etc.)
Product Rinse Recovery
Post Rinse Utilization
Automated Continuous
Processing
$15,000
unit
$10,000
$ 5,000
$ 6,000
$ 300/unit
$10,000
$ 7,500
$10,500
Agplicaticn^gf ,Ngw Systems Concepts
High Solids
Recovery System, including
2 valves
50,000 gal tank and
turbidity inter controls
Ice Cream Recovery
System, including
250 gal tank and
2 valves/unit with piping & fitting
Total Cost for a
230,000 kg/day
i[500,00 Ib/day)
dairy._plant
$ 30,000
$ 20,000
$ 7,800
$ 10,000
$ 7,500
$ 10,500
$104,000
Other new systems
$ 13,000
Cost not determinable at present time
110
-------
Item
Standard 190,000 1
(50,000 gal)
Silo tank
Cone shaped 190,000 1
(50,000 gal)
Silo tank
Standard 78,000 1
(20,000 gal)
Silo Pasteurizer Surge Tank
Standard 78rOOO 1
(20,000 gal)
Silo Pasteurizer Surge
Tank
Welded pipelines, fittings,
controls, installation;
4 products only --
30 valves
Full product line—
150 Valves
Drain Segregation
Air Actuated Valves
Central Hot Water
Table_23 (con't)
Unit Cost
$50,000
$60,000
$20,000
$2U,000
$ 2,500 x No.
of air-acutated
valves
Increase in Con-
struction cost
estimated at $.25/
square ft. include
manholes for each
department and drain
junction.
$700-800/valve
$330-820/100m
($100-250/100 ft.)
$3,000-10,000
Total Cost for a
230,000 kg/day
(500,00 Ib/day)
$100,000
$120,000
$100,000
$120,000
$ 75,000
$375,000
$ 50,000
$ 7,500
111
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Cost_of_End-Of-Pi2§_Treatment
Eiolcgical Treatment
A summary of the estimated capital costs and operating costs for
activated sludge, trickling filter and aerated lagoon sysstems are shown
in Figures 19 through 23. The data are based on 1971 costs. Operating
costs include power, chlorine, materials and supplies, laboratory
supplies, sludge hauling, maintenance, direct labor, and generally 10-
year straight-line depreciation.
Cost estimates for biological waste treatment systems are based on model
plants covering various discharge conditions representative of the dairy
industry. Specifically, raw waste BOC5 concentration of 500 mg/1, 1000
rng/1, 1500 mg/1 and 2000 mg/1 were selected, each at a flow volume of
187 cu m/day, 375 cu m/day, 935 cu m/day, 1872 cu in/day (50,000 gpd,
100,000 gpd, 250,000 gpd and 500,000 gpd). Cost analysis for waste
water volumes of 187 cu m/day (50,000 gpd) and less were based on
treatment by means of package plants. Package activated sludge was
considered although packed towers could be as efficient.
Substantial savings could be realized through use of prefabricated
plants for low volume discharge. Although field-instituted treatment
systems cost more even at larger capacities, they would generally
provide greater operational flexibility, greater resistance to shock
loads and flow surges, better expansion possibilities and higher average
treatment efficiencies. Cost estimates assume plants designed in
accordance with the parameters specified in Table 16, Section VII.
Capital ccst estimates for aerated lagoons for the four BOD cases--500
mg/1, 1000,mg/1, 1500 mg/1 and 2000 mg/1 — were almost identical.
Therefore, one case is indicated, namely 2000 mg/1 EOD5 at 187 cu m/day,
375 cu m/day, 935 cu m/day, 1872 cu m/day (50,000~gpd, 100,000 gpd,
250,000 gpd and 500,000 pgd) . Also operating cost estimates for the
four BOD5 concentrations were almost identical and only the operating
cost for the model lagoons receiving 2,000 mg/1 BOD5 is indicated. Fig.
22 shows operating costs including 10-year straight line depreciation.
Fig. 23 shews operating costs excluding depreciation.
Irrigation
Investment and costs were developed for three levels of waste water
discharge: 10, 40 and 80 thousand gallons per operating day. It is
assumed that the maximum daily discharge per acre is 20,000 gallons or
150 pounds EOC5. Although these levels may be considered high, no
problems should be encountered if the soil is a gravel, sand, or sandy
loam. During the winter months, it may be necessary to reduce the waste
water-BOD application per acre, particularly in the Lake States region
where many plants are located.
112
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FIGURE 19
CAPITAL COST (AUGUST, 1971)
ACTIVATED SLUDGE SYSTEMS (FOR DAIRY WASTEWATER)
FLOW (375 cu m/day)(100,000 GPD.)
5 8 7 S O 1O
Includes: Raw wastewater pumping, half-day equalization with diffused air,
aeration basin (36 hours) with diffused air supply system, settling, chlori-
nation feed system, chlorination contact basin, sludge recycle, aerobic sludge
digestion, sludge holding tank, sand-bed drying with enclosure and fans,
under-drain sand-bed pumping, laboratory, garage and shop facilities,
yardwork, engineering and land. Package treatment system does not
include sand beds, laboratory, garage and land cost.
113
-------
FIGURE 20
CAPITAL COST (AUGUST, 1971)
TRICKLING FILTER SYSTEM (FOR DAIRY WASTEWATER)
e 7 e a 10
FLOW (375 cu m/day)(100,000 GPD.)
Includes: Raw wastewater pumping, half-day equalization with diffused air,
trickling filter, settling chlorination feed system, chlorination contact
basin, recirculation pumping, sludge pumping, sludge holding tank, sand bed
drying with enclosure and fans, garage and facility, yardwork, engineering
and land.
114
-------
FIGURE 21
CAPITAL COST (AUGUST, 1971)
AERATED LAGOON (FOR DAIRY WASTEWATER)
e -7 e a 10
FLOW (375 cu m/day)(100,000 GPD.)
Includes: Raw wastewater pumping, aeration lagoon with high-speed floating
surface aerators, concrete embankment protection, settling basin, chlori-
nation contact basin, engineering and land.
115
-------
FIGURE 22
OPERATING COSTS (AUGUST, 1971)
ACTIVATED SLUDGE SYSTEM, TRICKLING FILTER SYSTEM,
AND AERATED LAGOON.
(FOR DAIRY WASTEWATER)
e 7 a a 10
FLOW (375 cu m/day)(100,000 GPD)
(Includes 10-year straight-line depreciation.)
Package treatment system does not include sludge sand beds, laboratory
and shop facilities.
116
-------
FIGURE 23
OPERATING COSTS (AUGUST 1971)
ACTIVATED SLUDGE, TRICKLING FILTER
AND AERATED LAGOON SYSTEMS
(FOR DAIRY WASTEWATER)
.•4 .5 .6 .7 .e ja \p
FLOW (375 cu m/day) (100,000 GPD)
s s 7 a e 10
(Excluding Depreciation or Amortization.)
Package treatment system does not include sand beds,
laboratory and shop facilities.
117
-------
Other assumptions are (1) minimum in-plant changes tc reduce waste water
or BOD discharge, (2) waste water and BOD discharge coefficients per
1,000 pounds cf M.E. are those used in the DPRA study (phase II, table
V-1), (3) and all plants operate 250 days a year.
Spray irrigation is more expensive to operate than a ridge and furrow
system that dees not require pumping. Spray irrigation investment for
processing plants discharging 10,000 GPD is $2,500-2,750, 40,000 GFE is
$4,200-$5,200 and 80,000 GPD is $7,000-$8,000. If whey is discharged
with the cheese plant waste water, the investments are $3,250, $7,200
and $13,000 respectively because of the need for additional land.
Annual tctal operating costs are $1,550 for the 10,000 GPD, $2,850 for
the 40,000 GPC, and $4,600 for the 80,000 GPD of waste discharge. For
the cheese plants discharging whey with the waste water, the annual
total cost are $1,600, $3,100, and $5,200 respectively. About 70
percent of these costs are variable and the remainder fixed.
Cn a per 1,000 pounds M.E. basis, the costs differ depending on the
product manufactured. For evaporated milk, ice cream, and fluid plants,
the cost decreases from 30 cents per 1,000 pounds of M.E. throughput to
14 cents for the 40,000 GPC discharge and 11 cents for the 80,000 GPE
discharge. Butter-powder plant costs per 1,000 pounds M.E. decrease
with increasing plant size and are 20, 10 and 8 cents respectively. The
cost of cheese plants without whey in the effluent are 14, 6, and 5
cents per 1,000 pounds of M.E., but the cost for the cheese plants
discharging 10,000 gallons of waste water including whey is 70 cents, 35
cents for the 40,000 GPD and 29 cents for the 80,000 GPD.
The ridge and furrow costs are lower and the economies of size
encountered fcr spray irrigation are not evident. Investment for
ditching and tiling land, the land itself and ditching to the disposal
site for 10,000 GPD is $1,600 (one-half acre) for fluid, ice cream,
evaporated irilk and cheese without whey discharge plants, $3,200 for
butter plants and $6,400 for cheese plants discharging whey. The
investments for the 40,000 and 80,000 GPD discharge are respectively
four and eight times the investment figures for the 10,000 GPD plants.
Annual operating costs (total) are assumed to be 20 percent of the tctal
investment. This may be considered high but these systems do require
more attention than they generally receive to keep them operating
properly at all times.
On a per 1,000 pounds of M.E. basis, the cost is 7 cents for fluid,
evaporated irilk and ice cream plants regardless of the size. The cost
is 8 cents per 1,000 pounds M.E. for butter-powder, 3 cents per 1,000
pounds M.E. for cheese plants without whey discharge, and 55 cents per
1,000 pounds M.E. for cheese plants with all whey in the effluent. In
any case, the cost per pound of finished product is very small.
Tertiary Treatment
118
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For further reduction cf BOD, suspended solids, phosphorus, and ether
parameters which biological systems cannot remove, tertiary treatment
systems wculd have to be used.
The capital and operating costs for such tertiary systems are given in
Table 24. The operating costs include ten-year straight line
depreciation costs. The total capital and operating cost represent the
costs required for treatment of secondary waste water for use in a
complete recycle process.
Economic Considerations
Today many -waste water treatment plants of approximately the same EOD-
remcval capacity vary as much as five fold in installed capital
investment. If due consideration is not given to economic evaluation of
various construction and equipment choices, an excessive capital
investment and high operating expense usually result. The engineer is
faced with defining the problem, determining the possible solutions,
economically evaluating the alternatives and choosing the individual
systems that, when combinded, will yield the most economical waste water
treatment process. Both capital investment and operating cost must be
considered carefully since it is sometimes more economical to invest
more capital initially in order to realize a reduced yearly operating
cost.
Of the three biological systems, that provide refined treatment, namely,
activated sludge, trickling filters and aerated lagoons, the aerated
lagoon system provides the most economical approach. Investment can be
minimized by providing weatherproof equipment rather than buildings for
equipment protection. Where buildings are required, prefabricated steel
structures set on concrete slabs are economically used.
119
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Lime precipitation
clarification
Ammonia air stripping
Pecartonation
Sand filtration
Reverse osmosis
Activated carfccn
Total
Tgble 24
Tertiary Treatment Sy£
Estimated Cagital Cost
0. 1
on
49
pping 53
28
28
111
139
4C8
Estimated Operatinq Cost*
C. 1
on
17.8
pping 16.1
10.9
19.9
70.7
5J^_8
194. 2
stems Cost
jQ971 Cost].
Flow Jmgd)
0.5
_{$ 1COO}_
80
94
39
79
467
347
1X106
J1971 Cost}.
Flow _{mgd)_
0.5
J(Z/1j_COO gal).
9.1
8.9
4.5
15.9
50.5
34^8
123.7
1.0
120
125
49
125
858
528_
1X805
1.0
7.8
6.2
3.5
13. 6
42.6
29^6
103.3
Lime precipitation
clarification
Ammonia air stripping
Recarbonaticn
Sand filtration
Reverse osmosis
Activated carbon
Total
*Includes 10-year depreciation cost
120
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Plant layout should always receive careful consideration. Simple
equipment rearrangement can save many feet of expensive pipe and
electrical conductors as well as reducing the distances plant operators
must travel. Maintenance costs are reduced by providing equipment-
removal devices such as monorails to aid in moving large motors and
speed reducers to shcp areas for maintenance. When designing pumping
stations and piping systems, an investigation should be made to
determine whether the use of small pipe, which creates large headlosses
but which is low in capital investment, is justified over the reverse
situation. Often a larger capital investment is justified because of
Icwer operating costs.
Table 25 depicts the relative costs of the three biological treatment
systems as practices in the chemical industry based on consistent unit
land and construction ccsts fcr each process.
Plant discharging less than 375 cu m/day (100,000 GPD) should consider
using package treatment systems. Such treatment systems chould result
in capital and operating costs savings.
Table_25
Biological System Cost Comparisions
As Applied in the Chemical Industry
Cost Ratio (relative to 1.0 as
_lowest_cost_SYStem]__
Land requirement
Capital Investment
Operating Ccst
Manpower
Maintenance
Chemical Usage
Fewer
Sludge Cispcsal
Activated
Sludge
1.0
1.8-2.5
Trickling
Filter
1.0-1. a
1.8-5.5
Aerated
Lagoons
2.0-100
1.0
2.5-5.5
6.0-12.0
1.2 +
40-100
50-150
2.2-5.0
4.0-8.0
1. 1 +
1.0
50-150
1 .0
1 .0
1.0
50-300
1 .0
and Deduction Benefits of Alternate End-of-Pip_e Treatment
Technologies
Incremental EOD5 removal and costs of treatment are compared for all
subcategories and three plant sizes 23, 135, and 340 kkg (50,000,
250,000 and 750,000 Ib) milk equivalent processed per day in Tables 26,
121
-------
27 and 28 respectively.
Three treatment alternatives are considered in each case:
1. Activated sludge
2. Activated sludge and sand filtration
3. vComplete recycling
The estimates are based on BOD5 loads (achievable through in-plant
control) and current average waste water volume discharges in each
sutcategrcy (See Table 13, Section V). Since a degree of reduction in
water consumption can be expected when in-plant controls are
implemented, the cost estimates are pessimistic. The cost per pound of
BOD5 remove for greater reduction (e.g. 96 percent to meet the proposed
guidelines) by activated sludge will not differ materially from those
for 90 percent reduction in Table 26-28 and would eliminate costs for
additional treatment such as sand filtration.
Non;Water_£ualitv_Aspjects_of
DairY_Waste_Treatment
The main ncn-water polluticnal problem associated with treatment of
dairy wastes is the disposal of sludge from the biological oxidation
systems. Varying amounts of sludge are produced by the different types
of biological systems. Activated sludge systems and trickling filters
produce sludge that needs to be handled almost daily.
Viaste sludge from activated sludge systems generally contains about 1%
solids. The amount of sludge produced ranges between 0.05 to O.Ska
solids per kg BOD5 removed. For extended aeration systems about 0.1 kg
solids will be produced per kg BOD5 removed.
Sludge frcrr trickling filters consists of slime sloughed off the filter
bed. This sludge settles faster than activated sludge and compacts at
solids concentrations greater than 1% solids. The amount of sludge
generated will be less than that produced by activated sludge systems.
Aerobic and anaerobic digestion of sludge generated from activated
sludge systems is recommended to render it innocuous, thicken it, and
improve its dewatering characteristics. Sludge thickening can preceed
digestion to improve the digestion ope-rations. Digested activated
sludge and thickened trickling filter sludges can be vacuum-filtered,
centrifuged cr dried on sand beds to increase their solids content for
better "handleability" before final disposal.
122
-------
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u -a
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-H -O O •* * -* O M O
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or M 0
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O tJ C fi "*J T!
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o^uu^rcr
123
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o t o
_ .
sr [o a;
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124
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^ f-M
-------
The energy required to comply with the effluent guidelines and
standard cf performance is largely that for pumping and aeration
associated with treatment facilities. The energy requirements
associated with in-plant control are so negligible as to be virtually
undetectafcle in the ever all power consumption in dairy products
processing plants.
Based en biological treatment (e.g., extended aeration) for the
portion cf the industry that constitutees point source discharges, and
including operation of treatment facilities presently in place, the
power demand to meet the 1977 limitations is estimated to be 145,000
kwh/day. An additional 3100 kwh/day would be required for compliance
with 1983 limitations. Depending on the size of the plant, a new source
would require 79 to 380 kw/mgd (1896 to 9120 kwh/mgd) discharged. These
estimates may be reduced if a number of plants opt for treatment
practices with lower power requirements such as irrigation.
126
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SECTION IX
EFFLUENT REDUCTION ATTAINABLE THROUGH THE APPLICATION
OF THE BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY AVAILABLE
(LEVEL I EFFLUENT LIMITATIONS GUIDELINES)
Introduction
The effluent limitations which must be achieved July I, 1977 are to
specify the degree of effluent reduction attainable through the
application cf the "Eest Practicable Control Technology Currently
Available", The Environmental Protection Agency has defined the best
practicable control technology currently available as follows.
Eest Practicable Control Technology Currently Available is generally
based upon the average of the best existing performance by plants of
various sizes, ages and unit processes within the industrial category
and/or subcategory. This average is not based upon a broad range of
plants within the dairy products processing industry, but based upon
performance levels achieved by exemplary plants.
Consideration must also be given to:
1. The total cost of application of technology in relation
to the effluent reduction benefits to be achieved from
such application;
2. the size and age of equipment and facilities involved;
3. the processes employed;
4. the engineering aspects of the application of various types
of control techniques;
5. process changes;
6. non-water quality environmental impact (including
erergy requirements.
Also, Best Practicable Control Technology Currently Available emphasizes
treatment facilities at the end of a manufacturing process but includes
the contrcl technologies within the process itself when the latter are
considered to be normal practice within an industry.
A further consideration is the degree of economic and engineering relia-
bility 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 confidence in the
127
-------
engineering and economic practicability of the technology at the time of
commencement of construction or installation of the control facilities."
Effluent Reduction Attainable
Through The Application Of
The Best Practicable Control
EOD
Eased upon the information contained in Sections. Ill through Section IX
of this report it has been estimated that the degree of EOD5 reduction
attainable through the application of the best practicable control
technology currently available in each industry subcategory is as
indicated in Table 29. The ECD5 loads under "Final Ff fluent", are the
suggested EOD5 effluent limitation guidelines to be met by July 1, 1977.
The derivation of the final effluent BOD5 limits are evident from Table
29. Although the final effluent loads were derived by assuming the use
of a biological treatment system to obtain 96% reduction of the raw
waste load reflecting good in-plant control, it is not implied that
plants must necessarily duplicate the raw waste loads and treatment
efficiency. It is possible that a number of plants may achieve the
indicated final effluent waste loads though a biological treatment
system operating at an average efficiency of less than 96% EOD_5
reduction, but receiving lower raw waste loads or operating in tandem
with a polishing operation such as sand filtration. In addition, an
entirely different approach such as disposal by controlled irrigation
may be employed.
Suspended Solids
Findings of this study indicate a 92% correlation between suspended
solids and EODJ in dairy waste water, with a mean of 40% suspended
solids to ECD5 rates.
End-of-pipe controls in existing dairy plants are designed primarily to
reduce BOC5 . An overall biological reduction efficiency of 96% ( or
possibly 90% through biological treatment and 60% further reduction
through sand filtration) has been selected for this paramater. A plant
that meets the guidelines, will probably have a biological treatment
system operating at close to 96% efficiency. A biological system
operating at that efficiency for EOD^ will perform at about 90%
reduction efficiency for suspended solids. Therefore, if the raw waste
load for suspended solids is equal to 40% of the BOD5 load, and the end-
of-pipe reduction is 96% for EOD5 and 90% for suspended solids, the
final effluent loads for suspended solids will have a 1:1 ratio with the
ECD5 loads, i.e., they will be numerically the same as those for BOD
shown in Table 29. The situation described above represents the highest
suspended solids loads that would result, i.e., when the final effluent
128
-------
cr>
CN
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4-1
<0
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ECD5 loads are met through biological treatment alone. When sand
filtration is added to meet the BOD5 limits, the suspended solids loads
will be numerically lower than the BOD5 loads. Therefore, it is
suggested that effluent limitation guidelines for suspended solids be
the same values suggested for BOD5, but expressed in kg suspended solids
per 100 kg EOD5 received.
Identification of Best Practicable Control Technology
The suggested raw waste loads and end-of-pipe waste reduction are
currently being achieved by a number of "exemplary" plants in the
industry. Other plants can acheive them by implementing seme or all of
the following waste control measures:
(a) In-Plant Control
1. Establishment of a plant management improvement program, as
described in detail in Section VII. Such a plan would cover an
educational program, fcr management and employees, installation of waste
monitoring equipment, improvement of plant maintenance, improvement of
production scheduling practices, quality control improvement, finding
alternate uses for products currently wasted to drain, and improvement
in housekeeping and product handling practices.
Specific attention should be given to recovery and use of whey rather
than discharge to the treatment system.
2. Improving plant equipment as described specifically under "Standard
Equipment Improvement Recommendations", items 1 through 13, in Section
VII.
(b) End-cf-Pipe Contrcl
1. Installation of a biological treatment system (activated sludge,
trickling filter, or aerated lagoon) , designed generally in accordance
with the suggested parameters set forth in Section VIII and operated
under careful management.
2. Installation of a biological treatment system followed by a
polishing step (e.g., sand filtration).
3. Where land is available, irrigating the water water by spray or
ridge and furrow, if this can be done economically and satisfactorily.
For Selection Of Best Practicable Control Technology Currently
Available
Keeping in mind the definition of best practicable control technology
currently available, the data contained in Table 29 were developed
utilizing the following basic methodology:
130
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(a) Paw ECE5 Load Achievable
Through In-Plant Control
1. foaste characterization data for identified plants were analyzed
in context with an evaluation of present management practices
and the engineered waste control improvement available at some
of those plants.
2. Waste load data for identified plants were compared with these
from the literature and with calculated values for complete
plants (based upon "Standard Manufacturing Processes", as
defined in the 1971 Kearney report).
3. Waste load data for single-product plants were tested against
those of multi-product plants, using the following relation:
EOD5 lead of multi-product plant (kg/100 kg) =
BQD5_load_of_single^p_roduct (kq/100_kg)-_x_BOD5_p_rocessed
Total EOD5 Received (kg)
4. Final values were selected, based on the results of the
preceeding analyses.
(b) EOD_ Peduction Achievable Through
End-Of-Pipe Control
Reported efficiencies of biological treatment systems in nine identified
plants (including activated sludge, trickling filters and aerated
lagoons) average 96.1% BCD5 (See Table 20). Those treatment plants, as
a whole, approach the highest average level of BOD5 reduction that can
be achieved with a well designed, well managed biological treatment
system.
131
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SECTION X
EFFLUENT PEDUCTION ATTAINABLE THROUGH THE APPLICATION OF THE EEST
AVAILABLE CONTROL TECHNOLOGY ECONOMICALLY ACHIEVABLE
The effluent limitations which must be achieved by July 1, 1983 are to
specify the degree of effluent reduction attainable through the
application cf the "Best Available Control Technology Economically
Achievable" The Environmental Protection Agency has defined this level
of in the following terms:
"This level of technology is not based upon an average of the best
performances within an industrial category, but is to be determined by
identifying the very best control and treatment technology employed by a
specific point source whin the industrial category or subcategory; where
a technology is readily transferable from one industry or process to
another, such technology may be identified as applicable. A specific
finding irust be made as to the availability of control measures and
practices to eliminate the discharge cf pollutants, taking into account
the cost cf such elimination, and:
1. the age of equipment and facilities involved;
2. the process employed;
3. the engineering aspects of the application of various
types of control techniques;
4. process changes;
5. ccst of achieving the effluent reduction resulting
from application of technology;
6. non-water quality environmental impact (including
energy requirements) .
In contrast to the best practicable control technology currently
available, the best available control technology economically achievable
assesses the availability in all cases of in-process controls as well as
control or additional treatment techniques employed at the end of a
production process. In-process control options available which should
be considered in establishing control and treatment technology include,
but need net be limited to, the following:
1. Alternative Water Uses
2. Water Conservation
133
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3. Waste Stream Segregation
4. Water Reuse
5. Cascading Water Uses
*
6. Ey-Product Recovery
7. Reuse of Waste Water Constituent
8. Waste Treatment
9. Good Housekeeping
10. Preventive Maintenance
11. Quality Control (raw material, product, effluent)
12. Monitoring and Alarm Systems
Those plant processes and control technologies which at the pilot plant,
semi-works, or other level, have demonstrated both technological
performances and economic viability at a level sufficient to reasonably
justify investing in such facilities may be considered in assessing
technology. Best available technology control economically achievable
is the highest degree of control technology that has been achieved or
has been demonstrated to be capable of being designed for plant scale
operation up to and including "no discharge" of pollutants. Although
economic factors are considered in this development, the costs for this
level of control is intended to be the top-of-the-line of current
technology subject to limitations imposed by economic and engineering
feasibility. However, it may be characterized by some technical risk
with respect to performance and with respect to certainty of costs.
Therefore, attainment of this technology may necessitate some
industrially sponsored development work prior to its application.
Eduction Attainable Through the Ap_p_lication of the Ee§t
Available Control Technology l£onomicallY Achievable
EOD5
Eased on the information contained in Section VII and the data base of
this report, it has been estimated that the degree of effluent reduction
attainable through the application of the best available technology
economically achievable in each industry subcategory is as indicated in
Table 30. The BOD5 loads under "Final Effluent" are the suggested
monthly average effluent limitations guidelines to be met by July 1,
1983.
134
-------
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Suspended Sclids
Eased on the same analyses and rationale described under "Suspended
Solids" in Section IX of this report, it is suggested that the effluent
limitation guidelines for suspended solids be numerically the same as
the EOD^ guidelines (Table 30) , but expressed in kg suspended solids
per 100 kg EOD5 received.
I^entificaticn of Best Available Control Ischnology l22D2IDi££!llY
Achievable
The suggested raw waste loads and end-of-pipe waste reduction are
currently teing achieved by a few "exemplary" plants in the industry.
Other plants can achieve them by implementing some; or all of the
following waste control measures:
(a) In-Plant Control
1, Establishment of a plant management improvement program, as
described in Section VII. Such a plan would cover an educational
program for management and employees, installation of waste monitoring
equipment, improvement of plant maintenance, improvement of production
scheduling practices, quality control improvement, finding alternate
uses for products currently wasted to drain, and improvement in product
handling practices.
2. Improving plant equipment as described specifically under "Standard
Equipment Improvement Recommendations", items 1 through 13, in Section
VII.
3. Improving plant equipment as described specifically under "New
Concepts fcr Equipment Improvement" items 1 to 4, in Section VII.
4. Applying process improvements, as described specifically under
"Waste Management Through Process Improvements", items (a) through (h),
in Section VII.
5. Implementing systeirs improvements, as described specifically under
"Waste Management Through Systems Improvements", items (1), (2) and (3)
of "Waste Control Systems now in use", in Section VII.
(b) End-Of-Pipe Control
1. Installation of a biological treatment system (activated sludge,
trickling filter, or aerated lagoon) designed generally in accordance
with the suggested parameters set forth in Section VIII, and operated
under good managmement.
2. Installation of a sand filter or ether polishing steps of adequate
capacity
136
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3. Where land is available, irrigating the waste water by spray or
ridge and furrow, if this can te done economically and satisfactorily.
H§iiPH§i§ ^2£ §§i§£iiP.D °f Best Available Control Technglocjy
EcgnoriicallY Achievable
Keeping in mind the pertinent definition of technology, the data
contained in Table 30 were developed utilizing the following basis
methodology:
(a) Raw ECD5 Load Achievable Through
In-Plant Control
Essentially the same as described in Section IX for Level L, but
slightly reduce considering:
(1) the performance of the best among the better plants in each sufccate-
gory, and (2) the application of new engineering improvements not widely
used in the industry.
(b) BOD5 Feducticn Achievable
Through End-of-Pipe Control
A EOD5 reduction efficiency of 96% was selected for biological systems,
based on the performance data of nine identified plants contained in
Table 20. This is followed by a polishing operation to attain the
specified percent of waste reduction.
137
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SECTION XI
NEW SOURCE PERFORMANCE STANDARDS
IStroducti.cn
In addition to guidelines reflecting the best practicable control
technology currently available and the best available control technology
economically achievable, applicable to existing point source discharges
July 1, 1977 and July 1, 1983 respectively, the Act require that
performance standards be established for "new sources." The term "new
source" is defined in the Act to mean "any source, the construction of
which is commenced after the publication of proposed regulations
prescribing a standard of performance."
The Environmental Protection Agency has defined the appropriate
technology in the following terms: "The technology shall be evaluated
by adding to the consideration underlying the identification of the best
available control technology economically achievable 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, the technology is to be based upon an analysis of how the
level of effluent may be reduced by changing the production process
itself. Alternative processes, operating methods or other alternatives
must be considered. However, the end result of the analysis will be to
identify effluent standards which reflect levels of control achievable
through the use of improved production processes as well as control
technology, rather than prescribing a particular type of process or
technology which must be employed. A further determination which must
be made for the technology is whether a standard permitting no discharge
of pollutants is practicable."
At least the following factors should be considered with respect to
production processes which are to be analyzed in assessing the
technology:
1. the type of process employed and process changes
2. operating methods
3. batch as opposed to continuous operations
H. use of alternative raw materials and mixes of raw
materials
5. use of dry rather than wet processes (including
substitution of recoverable solvents for water)
6. recovery of pollutants as by-products
139
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Effluent_Feduction_Attai.nable_in_New_ Sources
Because of the large number of specific improvements in management
practices and design of equipment, processes and systems that have some
potential of development for application in new sources, it is not
possible to determine, within reasonable accuracy, the potential waste
reduction achievable in such cases. However, the implementation of many
or all of the in-plant and end-of-pipe controls described in Section VII
should enable new sources to achieve the waste load discharges defined
in Section X.
The short lead time for application of new source performance
standards (less than a year versus approximately 4 and 10 years for
other guidelines) affords little opportunity to engage in extensive
development and testing of new procedures. The single justification
that could be made for more restrictive limitations for new sources than
for existing sources would be one of relative economics of installation
in new plants versus modification in existing plants. There is no data
to indicate that economics of new technology in dairy products
processing is significantly weighted in favor of new plants.
The attainment of zero discharge of pollutants does not appear to be
feasible fcr dairy product plants other than those with suitable land
readily available for irrigation. Serious problems of sanitation are
associated with complete recycle of waste waters and the expense
associated with the complex treatment system that would permit complete
recycle (see Figure 18 and Tables 26 through 28) are excessive.
In view of the foregoing, it is recommended that the effluent
limitations for new sources be the same as those for best available
control technology economically achievable found in Section X.
140
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Section XII
ACKNOWLEDGEMENTS
The Environmental Protection Agency wishes to acknowledge the
contributions to this project by A. T. Kearney, Inc., Chicago, Illinois.
Messrs. David Asper, David Dajani and Ronald L. Orchard, ably assisted
by their consultant Dr. W. James Harper of Ohio State University,
conducted the technical study and drafted the initial report on which
this document is based. Mr. Joseph H. Greenberg served as Project
Officer.
Appreciation is extended to the many people and companies in the
dairy products processing industry who cooperated in providing
information and data and in making a number of their plants available
for inspection and sampling. Special recognition is due the Task Force
on Environmental Problems of the Dairy Industry Committee for their role
in facilitating contact with representative segements of the industry
and many other contributions.
Indebtedness to those in the Environmental Protection Agency who
assisted in the project from inception of the study through preparation
and review cf the report is acknowledged. Especially deserving
recognition are: Max Cochrane, Ernst Hall, Frances Hansborough, Gilbert
Jackson, Fay McDevitt, Ronald McSwinney, Acquanetta McNeal, Walter
Muller, Judith Nelson, John Riley, Jaye Swanson, and George Webster.
141
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SECTION XIII
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129, Sewage_Lao[ggn^_in_the_PcckY_Mguntains. D. P. Green
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130. Aerated_Lac[ggnj_Treat_Minnesgta_Tgwn^s_Wastes. J. B. Neighbor
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cf Feed Science, North Carolina State University.
December, 1972.
147. Theoriej^andjPractices_gf_Industrial_Waste_Treatinent
Nelson I. Nemetow. Addison-Wesley Publishing Co., Inc.
Reading, Massachusetts. 1963.
148. CheinistrY_for_SanitarY_Engineers. Clair N. Sawyer,
Perry L. McCarby. McGraw-Hill Book Co., New York,
1967.
149. P£Ocedural_Manua l_f or_Eval ua tinc[_the_Per f orrnan ce_of
w§ste_water_Treatment_Plants. Environmental Protection
Agency, Washington, D.C. Contract No. 68-01-0107.
153
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SECTION XIV
GLOSSARY
Demand
Oxidation
Churned
Buttermilk
Demand
Chlorine Contact
(Or five-day BOD5) . Is the amount of
oxygen consumed by microorganisms to
assimilate organics in waste water over
a five day period at 20° C. BOD5 is
expressed in mg/1 (or ppm) and is the
most common yardstick at present to
measure pollutional strength in water.
The process whereby living organisms
in the presence of oxygen convert
the organic matter contained in waste-
water into a more stable or a mineral
form.
Byproduct resulting from the churning
of cream into butter. It is largely
defatted cream and its typical com-
position is 91% water. 4.5% lactose,
3.4% nitrogenous matter, 0.7%ash
and 0.4% fat. Churned or "true"
buttermilk is distinguished from cul-
tured buttermilk, which is a ferment-
ation product of skim milk. The latter
is sold in the retail market and re-
ferred to simply as "buttermilk".
Is the amount of oxygen provided by
potassium dichromate for the oxidation
of organics present in waste water. The
test is carried out in a heated flask
over a two hour period. One of the
chief limitations of the COD test is
its inability to differentiate between
biologically oxidizable and biologically
inert organic matter. Its major advan-
tage is the short time required for
evaluation when compared with the
five-day BOD test period. COD is ex-
pressed in mg.l or ppm.
A detention basin where chlorine is
diffused through the treated effluent
which is held a required time to provide
the necessary disinfection.
155
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Condensed
Cultured Products
Effluent
Ratio
The term "condensed" as used in
this report, applies to any liquid
product which has been concentrated
through removal of some of the water
it normally contains, resulting in
a product which is still in the
liquid or semi-liquid state. When
applied to milk, the term "condensed"
is used interchangeably with "evap-
oprate" to designate milk which has
been concentrated milk. Commercially,
however, the term "evaporate milk"
is commonly used to define unsweetened
concentrated milk.
Fermentation-type dairy products
manufactured by innoculating different
forms of milk with a bacterial culture
This designation includes yogurt,
cultured buttermilk, sour cream, and
cultured cream cheese, among other
products.
Waste containing water discharged
from a plant. Used synonymously
with "waste water" in this report.
An auto oxidation of cellular material
that takes plance in the absence of
assimilable organic material to fur-
nish energy required for the replace-
ment of worn-out components of proto-
plasm.
An aeration tank loading parameter.
Food may be expressed in pounds of
suspended solids, COD, or BOD5 added
per day to the aeration tank, and
microorganisms may be expressed as
mixed liquor suspended solids (MLSS)
or mized liquor volatile suspended
solids (MLVSS) in the aeration tank.
The flow (volume per unit time) applied
to the surface area of the clari-
fication or biological recictor units
(where applicable) .
156
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Hydraulic
Loading
Influent
Ice Cream
MilJL. Equivalent
M.E.
The flow (volume per unit time)
applied to the surface area of
the clarification or biological
reactor units (where applicable),
Waste water or other liquid - raw
or partially treated; flowing into
a reservoir, basin, treatment pro-
cess or treatment plant.
Applied in a general sense, this
term refers to any milk-based
product sold as frozen food.
Food regulatory agencies define
ice-cream in terms of composition,
to distinguish the product from
other frozen dessert-type products
containing less milk-fat or none at
all, such as sherbert, water ices
and mellorine.
Quantity of milk (in pounds) to
produce one pound of product. A
milk equivalent can be expressed
in terms of fat solids, non-fat
solids or total solids, and in
relation to standard whole milk
or milk as received from the farm:
the many definitions possible
through the above alternatives
has resulted in confusion and
inconsistent application of the
The most widely used milk equiva-
lents are those given by the U.S.
Department of Agriculture,
Statistical Bulletin No. 362
"Conversion Factors and Weights
and Measures for Agricultural
Commodies and Their Products."
A mixture of activated sludge and
waste water undergoing activated
sludge treatment in the aeration
tank.
A means of expressing the degree of
acidity or basicity of a solution,
defined as the logarithm of the
reciprocal of the hydrogen ion
concentration in gram equivalent per
157
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Raw Milk
Raw Waste Load
Rate
Skim Milk
liter of solution. Thus at normal
temperature a neutral solution such
as pure distilled water has a pH of
about 7, a tenth-normal solution of
hydrochloric acid has a pH near 1
and a normal solution of strong
alkali such as sodium hydroxide
has a pH of nearly m.
Milk as received from the farm or
of standardized composition that
has not been pasteurized.
Numerical value of any waste
parameter that defines the
characteristics of a plant
effluent as it leaves the plant,
before it is treated in any way.
The rate of return of part of the
effluent from a treatment process
to the incoming flow.
A sewer intended to carry waste
water from home, businesses, and
industries. Storm water runoff
sometimes is coll€?cted and trans-
ported in a separate system of pipe
In common usage, skim milk
(also designated non-fat,
defatted, or "fat-free" milk)
from which that fat has been
separated as completely as
commercially practicable.
The maximum fat content is
normally established by law
and is typically 0.1% in
the United States. There is
also a common but not univer-
sal requirement that non-fat
milk contain a minimum
quantity of milk sclids other
than fat, typically 8.25%.
In many states the meaning
of the term skim milk is
broadened to include milk
that contains less fat
that the legal minimum for
whole milk, such as the low-
158
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Stagdard_Manufacturing
Process
Susggnded_ Solids
Viaste
Waste Load
Vvbey
fat sold in the retail
market. The term skim milk
used in this study refers
to non-fat milk.
Trickling filter slimes that
have been washed off the filter
media. They are generally quite
high in BOD5 and will degrade
effluent quality unless removed.
An operation or a series of
operations which is essential
to a process and/or which
produced a waste load that is
substantially different from
that of an alternate method
of performing the same
process. The concept was
developed in order to have
a flexible "building
block" means for charac-
terizing the waste from
any plant within an
industry.
Particles of solid matter in
suspension in the effluent
which can normally be removed
by settling or filtration.
Potentially polluting material
which is discharged or disposed
of from a plant directly to the
environment or to a treatment
facility which eliminates its
undesirable polluting effect.
Numerical value of any waste
parameter (such as EOC
content, etc.) that serves
to define the characteristics
of a plant effluent.
Waste-containing water discharged
from a plant. Used synonymously
with "effluent" in this report.
By-product in the manufacture of
cheese which remains after
159
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separating the cheese curd frcm
the rest of the milk used in the
process. Whey resulting from
the manufacture of natural cheese
is termed "sweet whey" and its
composition is somewhat differ-
ent to "acid whey" resulting from
the manufacture of cottage cheese.
Typically, whey is composed of
93% water and 7% solids, including
5% lactose.
Vjhole_Milk - In its troad sense, the term whole
milk refers to milk of coirposition
such as produced by the cow. This
composition depends on many
factors and is secisonal with fat
content typically ranging between
3.5% and 4.0%. The term whole
milk is also used to designate
market milk whose fat content has
been standardized to conform to a
regulatory definition, typically
3.5%.
160
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TABLE 31
METRIC UNITS
CONVERSION TABLE
ILTIPLY (ENGLISH UNITS)
ENGLISH UNIT ABBREVIATION
re
re - feet
itish Thermal
Jnit
itish Thermal
Jnit/pound
lie feet/minute
Die feet/second
jic feet
jic feet
)ic inches
;ree Fahrenheit
:t *
.Ion
.Ion/minute
•sepower
:hes
hes of mercury
nds
lion gallons/day
e
nd/square inch
gauge)
are feet
are inches
s (short)
by TO OBTAIN • (METRIC UNITS)
CONVERSION ABBREVIATION METRIC UNIT
hectares
cubic meters
ac
ac ft
BTU
BTU/lb
cf m
cfs
cu f t
cu f t
cu in
°F
ft
gal
gpm
hp
in
in Hg
Ib
mgd
mi
psig
sq ft
sq in
ton
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
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
yd
0.9144
kilogram-calories
kilogram calories/
kilogram
cubic meters/minute
cubic meters/minute
cubic meters
liters
cubic centimeters
degree Centigrade
meters
liters
liters/second
killowatts
centimeters
atmospheres
kilograms
cubic raeters/day
kilometer
atmospheres
(absolute)
square meters
square centimeters
metric tons
(1000 kilograms)
meters
:tual conversion, not a multiplier
161
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U.S. Environmental Protection
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