EPA 440/l-74/031_a


        Development Document for
 Proposed  Effluent Limitations Guidelines
 and New  Source Performance Standards
                  for the
                RENDERER
              Segment of the

           MEAT PRODUCTS
          Point Source Category
                 p
\
 UJ
 a
 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                AlUST 1974

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          DEVELOPMENT DOCUMENT

                   for

PROPOSED EFFLUENT LIMITATIONS GUIDELINES

                   and

    NEW SOURCE PERFORMANCE STANDARDS

                 for the

                RENDERER
             SEGMENT OF THE
   MEAT PRODUCTS POINT SOURCE CATEGORY
            Russell E. Train
              Administrator

              James L. Agee
  Assistant Administrator for Water and
           Hazardous Materials
               Allen Cywin
 Director, Effluent Guidelines Division

            Jeffery D. Denit
             Project Officer
              August, 1974

      Effluent Guidelines Division
 Office of Water and Hazardous Materials
  U. S. Environmental Protection Agency
        Washington, D. C.  20460

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                            ABSTRACT

This document presents the findings of an extensive study of  the
independent  rendering  industry  by the Environmental Protection
Agency  for  the  purpose  of  developing  effluent   limitations
guidelines,  Federal  standards  of performance, and pretreatment
standards for the industry, to implement Sections 304(b)  and  306
of  the  Federal  Water  Pollution Control Act Amendments of 1972
(the "Act") .

The rendering plants included in  the  study  were  those  plants
specifically  processing  animal  by-products  at  an independent
plant  (i.e., a plant located,  operated  and  managed  separately
from  meat  slaughtering  and packing plants).  Plants processing
fish by-products and  rendering  operations  carried  out  as  an
adjunct  to  meat  packing  plants  were  not included.   Effluent
limitations guidelines are set forth for the degree  of  effluent
reduction   attainable  through  the  application  of  the  "Best
Practicable Control  Technology  Currently  Available,"  and  the
"Best  Available  Technology Economically Achievable," which must
be achieved by existing point sources by July 1, 1977,  and  July
1,  1983,  respectively.   The  "Standards of Performance for New
Sources" set forth the degree  of  effluent  reduction  which  is
achievable   through   the  application  of  the  best  available
demonstrated control technology, processes, operating methods, or
other alternatives.  The proposed regulations  require  the  best
secondary  treatment technology currently available for discharge
into navigable water bodies by July 1, 1977, and for  new  source
performance   standards.    This  technology  is  represented  by
anaerobic  plus  aerobic  lagoons,  or  their  equivalent.    The
recommendation  for  July  1,  1983  is  for  the  best secondary
treatment  and  in-plant  control,  as  represented  by  in-plant
containment  and  separate  treatment or recycle of high strength
waste  waters,  and  a  final  sand  filter  added  to  the  1977
technology.   When suitable land is available, land disposal with
no discharge may be a more economical  option,  particularly  for
small plants.

Supportive  data  and  rationale  for development of the proposed
effluent limitations guidelines and standards of performance  are
contained in this report.

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                            CONTENTS
Section

I.       CONCLUSIONS                                          1

II.      RECOMMENDATIONS                                      3


III.     INTRODUCTION                                         5

         Purpose and Authority                                5

         Summary of Methods Used for Development of the
         Effluent Limitations Guidelines and Standards of
         Performance                                          6

         General Description of the Industry                  7

         Process Description                                  12


         Inedible Rendering                                   13

              Batch System                                    13

              Continuous Systems                               18

         Edible Rendering                                      -\Q

         Cooker Uses and Process Variations                   23

         Vapor Condensing                                      24

         Grease and Tallow Recovery                            25

         Solids Processing                                     26

         Odor Control                                          26

         Waste Water Sources                                   27

         Materials Recovery                                    28

         Hide Curing                                           29

IV.      INDUSTRY CATEGORIZATION                               31

         Categorization                                        31

         Rationale for Categorization                          31

              Waste Water Characteristics  and
                Treatability                                   31
              Raw Materials                                    34
              Manufacturing Processes                          35
                                 m

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                      CONTENTS  (Continued)

Section

              Processing Equipment                             36
              Size, Age, and Location  of  Production
                Facilities                                     40

V.       WATER USE AND WASTE CHARACTERIZATION                 43

         Waste Water Characteristics                           43

              Raw Waste Characteristics                        43
              Discussion of Raw Wastes                        44
              Sources of Waste Water                           48
              Raw Materials Receiving                          50
              Vapor Condensing                                 50
              Spills and Plant and  Truck  Cleanup              52
              Odor Control                                     54
              Hide Control                                     54
              Miscellaneous Sources                           56

VI.      SELECTION OF POLLUTANT PARAMETERS                    57

         Selected Parameters                                   57

         Rationale for Selection  of Identified Parameters     57

              5-Day Biochemical Oxygen Demand                 57
              Chemical Oxygen Demand                           60
              Suspended Solids                                 60
              Total Dissolved Solids                           62
              Total Volatile Solids                           63
              Grease                                           63
              Ammonia Nitrogen                                 64
              Kjeldahl Nitrogen                                65
              Nitrates and Nitrites                           66
              Phosphorus                                       66
              Chloride                                         67
              Fecal Coliforms                                    68
              PH                                               69
              Temperature                                      70

VII.     CONTROL AND TREATMENT TECHNOLOGY                     73

         Summary                                               73

         In-Plant Control Techniques                           73

              Condensables                                     75
              Control of High Strength Liquid Wastes          75
              Truck and Barrel Washings                        75
              Odor Control                                     76
              Plant Cleanup and Spills                        7g
                                IV

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                      CONTENTS  (Continued)
Section                                                       £§2®

VII.     CONTROL AND TREATMENT  TECHNOLOGY  (Continued)

         In-Plant Primary Treatment                            76

              Flow Equalization                               76
              Screens                                          77
              Catch Basins                                     78
              Dissolved  Air  Flotation                          79

         Waste Water Treatment  Systems                         84

              Anaerobic  Processes                              84
              Aerated Lagoons                                  88
              Aerobic Lagoons                                  88
              Activated  Sludge                                 90
              Rotating Biological  Contactor                    93
              Performance of Various Secondary Treatment
                Systems                                        94

         Tertiary and Advanced  Treatment                      96

              Chemical Precipitation                           96
              Sand Filter                                      98
              Microscreen-Microstrainer                       101
              Nitrification-Denitrification                    103
              Ammonia Stripping                               106
              Spray/Flood Irrigation                           107
              Ion Exchange                                     110

VIII.    COST, ENERGY AND NONWATER QUALITY ASPECTS            115

         Summary                                               115

         "Typical" Plant                                      124

         Waste Treatment Systems                               125

         Treatment and Control  Costs                           127

              In-Plant Control  Costs                           127
              Investment Costs  Assumptions                    ]27
              Annual Cost Assumptions                          131

         Energy Requirements                                  132

         Nonwater Pollution  by  Waste Treatment Systems        133

              Solid Wastes                                     133
              Air Pollution                                    134
              Noise                                            134

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                      CONTENTS  (Continued)
Section

IX.      EFFLUENT REDUCTION ATTAINABLE THROUGH THE
         APPLICATION OF THE BEST PRACTICABLE CONTROL
         TECHNOLOGY CURRENTLY AVAILABLE—EFFLUENT
         LIMITATIONS GUIDELINES                               137

         Introduction
                                                              I O /
         Effluent Reduction Attainable Through the
         Application of Best Pollution Control
         Technology Currently Available                       138

         Identification of Best Pollution  Control
         Technology Currently Available                       140

         Rationale for the selection of  Best Practicable
         Control Technology Currently Available               142

              Size, Age, Processes  Employed, and
              Location of Facilities                          142
              Data Presentation                               143
              Engineering Aspects of Control Technique
              Applications                                    144
              Nonwater Quality Environmental Impact          145

X.       EFFLUENT REDUCTION ATTAINABLE THROUGH THE
         APPLICATION OF THE BEST AVAILABLE TECHNOLOGY
         ECONOMICALLY ACHIEVABLE—EFFLUENT LIMITATIONS
         GUIDELINES                                           147

         Introduction                                         147

         Effluent Reduction Attainable Through Application
         of the Best Available Technology  Economically
         Achievable                                           148

         Identification of the Best Available Technology
         Economically Achievable                              150

         Rationale for Selection of the  Best Available
         Technology Economically Achievable                  154

              Size, Age, Processes  Employed, and
              Location of Facilities                          154
              Data Presentation                               154
              Engineering Aspects of Control Technique
              Applications                                    156
              Process Changes                                 156
              Nonwater Quality  Impact                         156

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                      CONTENTS  (Continued)
Section

XI.      NEW SOURCE PERFORMANCE  STANDARDS                     159

         Introduction                                          159

         EFFLUENT REDUCTION ATTAINABLE FOR NEW SOURCES        159

              Identification of  New Source Control
                Technology                                    160
              Technology Rationale for Section of
              New Source Performance Standards                162
              Pretreatment Requirements                       162

XII.     ACKNOWLEDGMENTS                                      165

XIII.    REFERENCES                                            167

XIV.     GLOSSARY                                              171
                                Vll

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                             FIGURES
Number

  1      Distribution of Rendering Plants by State            11

  2      General Flowsheet of Operations of a Typical
         Inedible Rendering Plant                             15

  3      Batch Cooker Rendering Process                       17

  4      Continuous Rendering - Duke Process                  20

  5      Continuous Rendering - Anderson Carver-Greenfield
         Process                                              22

  6      Manufacturing Processes of a Rendering Plant         32

  7      Average and Range of BOD5 by Raw Material Type       35


  8      Average and Range of BOD5 Data by Cooker Type        37

  9      Average and Range of BOD 5 Data by Condenser Type     33

 10      Average and Range of BOD5 Values for Three Size
         Groups of Plants and for All Plants Studied          41

 11      Typical Rendering Process and Waste Water Flow
         Arrangement                                          49

 12      Suggested Waste Reduction
         Program for Rendering Plants                         74

 13      Dissolved Air Flotation                              80

 14      Process Alternatives for Dissolved Air Flotation     83

 15      Anaerobic Contact Process                            87

 16      Activated Sludge Process                             91

 17      Chemical Precipitation                               98

 18      Sand Filter System                                   99

 19      Microscreen/Microstrainer                            102

 20      Nitrification/Denitrification                        104

 21      Ammonia Stripping                                    10g
                              ix

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                       FIGURES  (Continued)
Number                                                        Page



 22      Spray/Flood Irrigation System                         109

 23      Ion Exchange                                          109

 24      Waste Treatment Cost Effectiveness                    130

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                             TABLES

Number

  1      Inedible Tallow and Greases:  Use, By-Products,
         1960-1970                                            9

  2      Statistics by Employment Size of Establishment,
         1967                                                 12

  3      Raw Material and Product Yields for Inedible
         Rendering by Type of Animal                          14

  4      Product Yields for Inedible Rendering by Type of
         Raw Material                                         14

  5      Raw Waste Water Data on Rendering Plants
         by Equipment Type                                    39

  6      Summary of the Plant and Raw Waste Water
         Characteristics for the Rendering Industry           45

  7      Waste Water Flow and Raw Material Data on Off-Site
         Rendering Plants                                     46

  8      Correlation Coefficients of Raw Waste Load
         Parameters from the Field Sampling Results           47

  9      Summary of Concentrations of Undiluted Condensed
         Cooking Vapors                                       5]

 10      Summary of Waste Loads of Undiluted Condensed
         Cooking Vapors                                       53

 11      Waste Load Characteristics for Hide Curing at a
         Rendering Plant Versus Those for a Tannery           55

 12      Measured Waste Strengths of Tank Water and Blood
         Water                                                55

 13      Performance of Various Secondary Treatment Systems   95

 13A     Profile of Typical Plants by Size                    ]]5

 14      Likely Capital Expenditures by Plant Size to Meet
         Limitations with Condenser Recirculation as Needed   ng

 15      Estimated Waste Treatment Costs for Renderers
         with High Waste Water Volume                         -]20

 ISA     Total Annual and Operating Costs for Renderer
         with High Waste Water Volume

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                       TABLES  (Continued)

Number

 15B     Annual and Operating Costs Per  Unit Weight  of  Raw
         Material                                              l41

 16      Comparison of Most Likely and Maximum Investment
         with Condenser Recirculation                          122

 17      Total Annual and Operating Costs  for a  Rendering
         Plant to Meet the Indicated Performance              '"

 18      Annual and Operating Costs Per  Unit Weight  of  Raw
         Material for a Rendering Plant  to Meet  Indicated
         Performance                                           122

 19      "Typical" Plant Parameters for  Each Plant Size       124

 20      Waste Treatment Systems, Their  Use and
         Effectiveness                                         126

 21      Estimates of In-Plant Control Equipment Cost          128

 22      Recommended Effluent Limitation Guidelines  for
         July 1, 1977                                          139

 23      Effluent Limitations Adjustment Factors for Hide
         Curing

 24      Raw and Final Effluent Information for  Ten
         Off-Site Rendering Plants                             141

 25      Recommended Effluent Limitation Guidelines  for
         July 1, 1983                                          149

 26      Effluent Limitation Adjustment  Factors  for  Hide
         Curing                                                149

 27      Raw and Final Effluent Information for  Ten
         Off-Site Rendering Plants                             151-152

 28      Investment and Operating Costs  for New  Source
         Performance Standards                                 160

 29      Conversion Table                                         180

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                            SECTION I

                           CONCLUSIONS


The  study presented herein is a part of an overall investigation
of the meat processing (no slaughtering of  animals  accomplished
in   the  plants)  and  rendering   (accomplished  independent  of
slaughterhouses, packinghouses and poultry  processors)   industry
segments of the meat products point source category.

Because  of  evidence  developed  early  in the investigation, it
became  apparent  that  meat   processing   operations   differed
materially   from  rendering  operations  as  to  raw  materials,
processes, products and other factors.  As a result,  an  initial
categorization which split the two industry segments was utilized
to  facilitate  a  thorough analysis with a separate study report
for each, with the rendering industry segment presented herein.


A conclusion of this study is that the  rendering  industry  con-
stitutes   a  single  category.   Unless  otherwise  specifically
designated, all subsequent discussions of the rendering industry,
or  references  to  the  rendering  industry,   deal   with   the
independent  rendering operation or plants not included as a part
of livestock or poultry slaughtering, packing or processing.

The primary criterion for the establishment of the  category  was
the 5-day biochemical oxygen demand  (BOD5) in the total plant raw
waste  water.   Other  criteria  were  plant  size  and  type  of
processing equipment used in the plant.  Information relating  to
other  pollutants  and  the effects of such parameters as age and
location of plants, type of raw material,  production  processes,
and treatability of wastes all lent support to the categorization
decision.

The  wastes  from  rendering  plants  are  amenable to biological
treatment processes, and no materials harmful to municipal  waste
treatment processes were found.

The 1977 discharge limits for BOD5, suspended solids, and grease,
representing  the  average  of  the best treatment systems in the
rendering industry, are currently being met by a number of plants
included in the survey.  Several of the plants meeting the limits
discharge waste water to receiving  waters,  while  a  number  of
other  plants,  particularly  small  plants,  meet  the limits by
irrigating or ponding waste waters.  These limits, plus  a  fecal
coliform  limit,  are recommended for 1977.  The same limits plus
limitations on ammonia are  recommended  for  new  sources.   The
limits  for  ammonia  and  phosphorus  are  recommended  for  new
sources.  The nutrient limits for new  sources  represent  limits
being  met  by  the  majority  of  plants with the best treatment
systems.  It is estimated that there will be about  $2.1  million

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in  capital  costs  required  to  achieve  the 1977 limits by the
industry.

For 1983, effluent limits were determined as the best  achievable
in   the  industry  for  BOD5,  suspended  solids,  ammonia,  and
phosphorus.

It is estimated that the cost to achieve the 1983 limits  by  the
industry  will  be  $8.9 million.  The 1977 cost for the industry
represents about 7 percent, and the 1983  cost  approximately  30
percent  of  the $30 million spent by the industry in 1972 on new
capital expenditures.

It is also concluded that, where suitable and  adequate  land  is
available,  land disposal is a more economical option for meeting
discharge limits, particularly for small plants.

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                           SECTION II

                         RECOMMENDATIONS
Limitations recommendations for discharge to navigable waters  by
rendering   plants   for   July   1,   1977   are  based  on  the
characteristics of well operated secondary treatment plants being
used by the industry.  The limitations are for 5-day  biochemical
oxygen   demand   (BOD5) ,  suspended  solids,  grease,  and  fecal
coliform.  These limitations are 0.15 kg  BOD5/kkg  raw  material
(RM);   0.17  kg  SS/kkg RM; 0.10 kg grease/kkg RM; and 400 counts
fecal  coliform/100  ml.   Adjustments  in  the   BOD5   and   SS
limitations are provided for plants curing hides.

Recommended  New  Sources  Standards include the 1977 limitations
plus limitations on ammonia (NH3J, nitrites  and  nitrates  (NO2~
NO3) ,   and total phosphorus (TP).   The additional limitations are
also based on the performance characteristics  of  well  operated
secondary  treatment  plants.    These additional limitations are:
0.17 kg NH3 as N/kkg RM; and 0.05 kg TP/kkg RM.

Limitations  recommended  for   the   industry   for   1983   are
considerably  more  stringent  and are based upon the performance
characteristics of the best operated secondary treatment  systems
being  used  to  treat rendering waste waters.  These limitations
include the same pollutant parameters  as  included  in  the  new
source standards plus a limitation on the total Kjeldahl nitrogen
(TKN)   and  on  pH  range.   The  1983  limitations  are: 0.07 kg
BOD5/kkg RM; 0.10 kg SS/kkg RM; 0.05 kg grease/kkg  RM;  0.02  kg
NH3 as N/kkg RM; 0.05 kg TP/kkg RM; a pH range of 6.0 to 9.0; and
a   fecal coliform count of 400/100 ml.  Again, adjustments in the
BOD5 and SS limitations are provided  for  plants  curing  hides;
however,  these  adjustments  are smaller than those for the 1977
limitations.

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                           SECTION III

                          INTRODUCTION


                      PURPOSE AND AUTHORITY
Section  301(b)   of  the  Federal  Water  Pollution  Control  Act
Amendments  of  1972   (the  Act)   requires the 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
regulations providing guidelines for effluent limitations setting
forth the degree of effluent  reduction  attainable  through  the
application  of the best practicable control technology currently
available and the degree of effluent reduction attainable through
the application  of  the  best  control  measures  and  practices
achievable  including treatment techniques, 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
independent  renderers  sutcategory  of  the  meat products point
source category designated in Section 306.

Section 306 of the Act requires  the  Administrator,  within  one
year  after a category of sources is included in a list published
pursuant  to  Section  306 (b) (1)  (A)  of  the  Act,   to   propose
regulations establishing Federal standards of performance for new
sources  within  such categories.  The Administrator published in
the Federal Register of January 16, 1973  (38 F.R. 1624) a list of
27  source  categories.   Publication  of  the  list  constituted
announcement of the Administrator's intention of establishing the
off-site  rendering  plants  engaged in the manufacture of animal

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and marine fats and oils source category, which was  included  in
the list published January 16, 1973.
     SUMMARY OF METHODS USED FOR DEVELOPMENT OF THE EFFLUENT
       LIMITATIONS GUIDELINES AND STANDARDS OF PERFORMANCE

The  effluent limitations guidelines and standards of performance
proposed herein were developed  in  the  following  manner.   The
point  source  category  was  first  studied  for  the purpose of
determining  whether  separate  limitations  and  standards   are
appropriate   for   different  segments  within  a  point  source
category.  This analysis included a determination of whether dif-
ferences in raw material used,  product  produced,  manufacturing
process employed, equipment, age, size, waste water constituents,
and  other  factors  require  development  of  separate  effluent
limitations and standards for different  segments  of  the  point
source  category.  The raw waste characteristics for each segment
were then identified.  This  included  an  analysis  of   (1)  the
source  and  volume of water used in the process employed and the
source 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  (see
Section VI).  The result of this analysis was that there  was  no
reason  for  separate  limitations  and  standards  for different
segments of the industry.

The full range of control  and  treatment  technologies  existing
within  the  point source category was identified.  This included
identification of each distinct control and treatment technology,
including  an  identification  in  terms   of   the   amount   of
constituents   (including thermal) and the chemical, physical, and
biological characteristics of pollutants,  and  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  was  also  identified.   In  addition,  the
nonwater-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
identified.  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 outlined above, was then evaluated in order
to determine what levels  of  technology  constituted  the  "best
practicable    control   technology  currently  available,"  "best
available technology  economically  achievable,"  and  the  "best
available  demonstrated  control technology, processes, operating
methods,   or   other   alternatives."    In   identifying   such
technologies,  various  factors  were considered.  These  included
the total cost of application of technology in  relation  to  the

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effluent equipment and facilities involved, the process employed,
the  engineering  aspects  of the application of various types of
control    techniques,    process    changes,    nonwater-quality
environmental  impact  (including  energy requirements) and other
factors.  The data for identification and analysis  were  derived
from  a  number  of  sources.   These sources included Refuse Act
Permit  Program  data;  EPA  research   information;   data   and
information  from  North  Star  files  and  reports;  a voluntary
questionnaire issued through the National  Renderers  Association
(NRA);  qualified  technical  consultants; and on-site visits and
interviews at several exemplary rendering plants in various areas
of the United States.  Questionnaires provided information on  49
plants;  12  of  these  were  also included in the field sampling
survey.  Two other plants that did not submit questionnaires were
also sampled.  Thus, the total number of plants included in  this
study  was  51,  or  about  11  percent of the off-site rendering
industry.  All references used in developing the  guidelines  for
effluent limitations and standards of performance for new sources
reported herein are included in Section XIII of this document.


               GENERAL DESCRIPTION OF THE INDUSTRY

The  off-site  rendering industry falls within industry No. 2077,
Animal and Marine Fats and Oils.1  SIC 2077 includes;

     "Establishments primarily  engaged  in  manufacturing  animal
     oils,  including  fish  oil  and other marine animal oils and
     fish and animal meal; and those rendering inedible grease and
     tallow   from   animal   fat,   bones,   and   meat   scraps.
     Establishments  primarily  engaged  in manufacturing lard and
     edible tallow and stearin are classified in Group 201;  those
     refining   marine  animal  oils  for  medicinal  purposes  in
     Industry  2833;  and  those  manufacturing  fatty  acids   in
     Industry 2899.

     "Fish liver oils, crude  Oil, neat's-foot
     Fish meal               Oils, animal*
     Fish oil and fish oil   Oils, fish and marine animal: herring,
         meal                 menhaden, whale  (refined), sardine
     Meat meal and tankage*  Rendering plants, grease and tallow*
     Neat's-foot oil          Stearin, animal:  Inedible"
     Oil and meal, fish

*The  off-site rendering industry covered in this report includes
only meat-meal and tankage; oils, animal; and  rendering  plants,
grease and tallow.

Rendering  is  a process to convert animal by-products into fats,
oils, and proteinaceous solids.  Heat is used to  melt  the  fats
out  of  tissue,  to coagulate cell proteins and to evaporate the
raw  material moisture.  Rendering  is  universally  used  in  the
production  of  proteinaceous  meals from animal blood, feathers,
bones, fat tissue, meat scraps, inedible  animal  carcasses,  and
animal  offal.   The  rendering  industry consists of off-site or


                            7

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independent Tenderers and  on-site  or  captive  renderers.    The
independent  renderers  reprocess discarded animal materials  such
as fats, bones, hides, feathers, blood, and offal  into   saleable
by-products,   almost   all  of  which  are   inedible  for human
consumption, and "dead stock"  (whole  animals  that die  by accident
or through natural causes).  Captive  rendering operations, on the
other hand, are usually conducted as  an adjunct  to   meat  packing
or  poultry  processing  operations   and  are  housed  in a separate
building on the same premises.  consequently,  captive  renderers
produce  almost  all  of   the  edible  lard and  tallows  made  from
animal fats in addition to producing  inedible  by-products.    Two
usual  process  differences  between  rendering  edible  or inedible
materials are the composition  and  freshness  of the   materials,
and,  second,  the process used.  Edible  rendering requires fresh
 (inspected) fats and  usually  is  conducted  by a  wet  or   low
temperature  process.   These  processes   do  not  evaporate   raw
material  moisture  during  cooking,   and therefore  require  an
additional  step  to  separate water  from   the edible  products.
Inedible rendering is accomplished exclusively  by  dry  rendering
where  the  raw  material  is  cooked  with no  addition  of steam or
water.

Rendering of animal by-product materials  is one  of   the   original
recycling industries; it began as an  industry over  150 years  ago.
During the  past two decades  the production of inedible tallow and
grease   (the   major  products  of rendering plants)  has  increased
 from 2.3 billion pounds, worth $150 million in  early 1950, to  an
 estimated   5.4 billion  pounds, worth $430 million  for 1971-72.2
 This increase  is largely caused by an expansion in  livestock  and
 poultry  production.  The  increase resulting  from increased plant
 efficiency  is  negligible.

 The United  States  is the world's leading  producer, consumer,   and
 exporter   of   tallow  and  grease.    Since the early  1950's, the
 United  States  has  accounted  for 55 to 60  percent of   the  world's
 tallow  and  grease  output.  The export market  has been  the largest
 single   outlet for inedible  tallow and grease,  consuming about 50
 percent  of  the domestic   output.   Table  1  lists  the  various
 markets  for   inedible  tallows and greases and shows  the current
 use  of  tallow  and  grease  in  both  soap    and    fatty   acid
 manufacturing  to  be about one-half of that for animal feeds.  It
 also shows  that between 1960 and 1970 there was a  slight decrease
 in their use for soap manufacturing,  which is more than offset by
 a 2.5 times increase in their  use for animal  feeds.

Off-site renderers  send out  trucks daily   on  regular   routes  to
 collect  discarded  fat and  bone trimmings, meat scraps, bone and
offal,  blood,  feathers,   and  entire  animal  carcasses  from  a
variety  of sources:  butcher shops,  supermarkets, restaurants,
poultry processors, slaughterhouses,   and  meat  packing  plants,
farmers and ranchers.  Each  day the rendering industry,  including
both on-site  and independent  plants,   processes  more than 80
million pounds of  animal fat and bone materials, in   addition  to
dead stock, that  would otherwise have to be  suitably  disposed of
to prevent  its becoming a  national public health problem.3

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   Table 1.   Inedible Tallow and  Greases:   Use,  By-Products,  1960-1970^
Year
Beginning
October
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970*
Soap

732
702
688
660
690
649
665
631
637
601
615
Animal
Feeds
Fatty
Acids


443
732
774
861
714
855
972
990
1061
1093
1140
351
402
433
478
530
575
547
576
585
610
568
Lubricants
and Similar
Oils
Million Pounds
70
79
78
91
102
107
98
89
98
97
89
Other
Exports


151
177
151
230
203
208
283
291
289
320
214
1769
1710
1738
2338
2155
1962
2214
2212
2009
2051
2591
Total

3516
3802
3862
4658
4394
4356
4779
4789
4679
4772
5217
*Preliminary data; based on census reports,

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The independent renderer pays for the raw  material  he  collects
and  he manufactures usable products, such as tallow for soap^and
for derivatives for the chemical industry, and meal and  inedible
grease  for  animal  and poultry feed.  Because of the perishable
nature of the raw material collected, renderers must process  the
material  without  delay.  This normally restricts the collection
area to a 150-mile radius around  the  plant.   However,   if  the
renderer  is  only  picking  up  restaurant grease, which  is more
stable, it is possible that he may travel greater distances.

Off-site renderers are located in both  urban  and  rural  areas.
The  urban  renderer  normally has more modern equipment,  shorter
routes for pick-up of  raw  materials,  a  better  grade   of  raw
materials, and high production rates that enable his operation to
run  more  efficiently.  The urban renderer usually has access to
municipal sewer and has the option of either  providing  his  own
treatment system or buying into the municipal plant.  The  country
renderer, on the other hand, normally has older equipment, longer
routes,  picks  up  dead  stock, and has a lower capacity  system.
The  location of the rural renderer does not  permit  him   to  tie
into  a  sewer  facility  and, therefore, he normally has  his own
waste  treatment facilities.

Figure 1 provides a general  idea  of  the  distribution   of  all
rendering  plants throughout the country; it includes both edible
and  inedible rendering plants, on-site as  well  as  independent.
Also,  fish  rendering  plants  are included in the state  totals.
Judging  from Figure 1, the  number  of  rendering  facilities  is
greatest  in the central states.  However, the National Renderers
Association indicated that production from facilities  along  the
Atlantic seaboard equals that from facilities located between the
Appalachian Mountains and the Rockies.

Data from the  1967 Census of Manufactures* is summarized in Table
2.    These  data  provide  some information regarding the  size of
existing rendering plants.  However, since the data reflect  only
69   percent  of  the  industry,  the  distribution of plant sizes
should be considered only approximate.  Plants range in size  from
small  operations employing one to four men with annual  sales  of
about  $100,000  to  large operations employing over 100 men with
sales  from  $5  to  $10  million.   An  average  plant  could  be
characterized  as  employing  23  men  and having annual sales of
approximately  $1 million.  Judging from our  recent  observations
of the industry, it would appear that these figures are no longer
correct,  since many companies have consolidated their plants and
installed more modern  gear  with  larger  capacities.   However,
because we measured size not by products, but rather by amount of
raw    material   handled,  it  is  difficult  to  make  an exact
comparison.  In any event,  based  on  the  assumption  that  the
average  size  plant  is as found in this study—a plant handling
59,000 kg (130,000 pounds) per day of raw material—and based  on
average  yield  values  and on current market prices, the  average
plant  would have annual sales of about $1.5 million.
                               10

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Figure
1.   Distribution of Rendering Plants by State2

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As of 1968 -there were   770   firms   operating  in  850  facilities
engaged  in  the  rendering   of  inedible animal matter.2  Of this
number, some 460 were operated   by  independent  renderers   (off-
site) ,  330  were  controlled by   the  meat  packing and poultry
industries  (on-site), and the remainder were owned by  a  variety
of concerns.  It is  estimated that some 275, or about 83 percent,
of   the  plants controlled by the  meat industry are also involved
in edible rendering.  The industry estimates that the  number  of
independent


         Table 2.  Statistics by Employment Size of Establishment, 1967^

Establishment
With an Average
of:
1 to 4 employees
5 to 9 employees
10 to 19 employees
20 to 49 employees
50 to 99 employees
100 to 249 employees
TOTALS

Number of
Establishments
132
103
127
157
51
18
588

Number of
Employees
300
700
1800
4800
3500
2600
13,700
Value of
Shipments
(millions of
dollars)
12.0
27.9
62.2
207.1
117.1
131.0
557.9*
      *Total value of shipments from all sources.
 renderers  is  now  450 or less, and they expect an additional  50
 plants, primarily small, to close because of the economic   impact
 on  capital investment caused by enforcement of new air  and water
 pollution standards.5 This conclusion is based  on  the  argument
 that,  because  tallow  and  protein meal products from  rendering
 plants must compete  on  the  open  commodity  market,   pollution
 control costs can not be passed off to the consumer as is  done  in
 the  other  industries  where  prices  are raised to  absorb these
 costs.
                        PROCESS DESCRIPTION
 A general flow sheet of the  processes  of  a  typical   inedible,
 independent  rendering  plant  is  shown in Figure  2.   (A  general
 flow sheet for edible rendering  would  be  similar.)    The  bulk
 material  (offal,  bones, and trimmings) collected  by independent
 renderers is normally dumped into a pit from which  it is conveyed
                                 12

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to a grinder.  Liquid wastes collected on the bottom of the  pits
are  usually  sewered, although in a few cases the liquid, if not
an excessive amount, is pumped on  top  of  the  materials  being
conveyed  to  the  grinder or the cooker.  In the case of poultry
offal, it is not always  necessary  to  grind  the  raw  material
before  cooking unless it contains a large number of whole birds.
Feathers, if they are not mixed with poultry  offal,  are  dumped
directly  on  a  floor to allow excess liquid to drain off.  Off-
site rendering plants normally process feathers  separately  from
poultry  offal.   Oils  are  poured into receiving tanks and from
there go directly to cookers.

The process of rendering consists of two essential steps.  First,
the raw material is heated or cooked to melt the tallow or grease
and permit the phases  to  separate  and,  in  the  dry  inedible
process,  to  evaporate  the  moisture.  Also, the animal fibrous
tissues are conditioned.  The second  step  is  a  separation  of
tallow  or  grease from the solid proteinaceous material.  Proper
conditioning of the fibrous tissue is important to accomplish the
second step efficiently.  In edible rendering little, if any,  of
the  raw material moisture is evaporated; the cooking is normally
conducted at a lower temperature  (49°to 82°C, or 120°  to  180°F)
to  improve the quality of the grease and tallow.  However, since
this is done almost exclusively by on-site renderers, it will not
be discussed in great detail in this report.

The product yields and process control of the  cookers  are  very
dependent  on  the nature of the raw materials.,  For example, the
moisture content of raw materials ranges from 20 percent moisture
for beef fats to 87 percent moisture for blood.  Tables 3  and  4
give  the  percentage  of  yield  of a number of common materials
processed by independent rendering  plants.   The  percentage  of
moisture,  of  course, can be calculated by subtracting the total
percentage  of  yield  of  fat  and  solids  from  100   percent.
Additional  information  on  the  amount  and  type of animal by-
products processed for various  animal  sources  and  on  product
yields  can  be  found in reference 6 which is also the source of
the information presented in Tables 3 and 4.

                       INEDIBLE RENDERING

                          Batch System

         Note:  Throughout the discussion of production methods
         and concepts which follows, the use of trade names is
         included as necessary to facilitate the explanations
         presented and understanding by the reader.  Use of such
         trade names, however, should in no way be construed as
         a product endorsement or recommendation by the U. S.
         Environmental Protection Agency.


Batch rendering, a  dry  process,  is  a  cooking  and  moisture-
evaporation  operation  performed  in a horizontal steam jacketed
cylindrical "cooker" equipped with an agitator.  It  is  referred


                               13

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Table 3.  Raw Material and Product Yields for Inedible Rendering by Type of Animal


By-Products from Animals
Steers
Cows
Calves
Sheep
Hogs
Broilers (offal & feathers)
Offal and Bone
per Head,
kg (lb)
41-45 (90-100)
50-57 (110-125)
6.8-9.1 (15-20)
3.6-4.5 (8-10)
4.5-6.8 (10-15)
0.45 (1)
Tallow and
Grease,
Percent
15-20
10-20
8-12
25-35
15-20
4
Cracklings
at 10-15% Fat,
Percent
30-35
20-30
20-25
20-25
18-25
26
              Table 4.
Product Yields for Inedible Rendering by Type of
Raw Material6
By-Products from
Materials
Shop fat and bones
Dead cattle
Dead cows
Dead hogs
Dead sheeu
Poultry offal (broiler)
Poultry feathers
Blood
Tallow and
Grease ,
Percent
37
12
8-10
30
22
14
—
—
Cracklings
at 10-15% Fat,
Percent
25
25
23
25-30
25
4
12 (meal)
12-14 (meal)
                                       14

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                       PROCESSES
                                                                      WASTE WATER
     DRYING
                    RAW MATERIAL
                     RECOVERY
                    CRUSHING AND
                      GRINDING
                      COOKING
                    AND MOISTURE
                      REMOVAL
LIQUID -SOLID
 SEPARATION
                                   LIQUID
                  I  MEAL GRINDING
                  j  AND SCREENING
                      BLENDING
                           SOLIDS
                        MEAL
                      STORAGE
                      SHIPPING
                        HIDE
                      CURING
  GREASE
CLARIFYING
                         GREASE
                        STORAGE
                                             SHIPPING
                                                                 ODOR
                                                                CONTROL
                                            VAPOR
                                          CONDENSING
                                __ 	_.J
                                           PLANT AND
                                         TRUCK WASHING
                                            	1
                                                                               MATERIAL
                                                                               RECOVERY
                                                                                 SYSTEM
                                                                                   T
                                                                SANITARY
                                                                FACILITIES
                                                                               TREATMENT
                                                                                SYSTEM
                                                                      •WASTE WATER FLOW
                                                                    •*- PRODUCT AND MATERIAL FLOW
Figure 2.   General Flowsheet  of Operations  for a  Typical  Inedible Rendering  Plant
                                             15

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to  as a dry rendering process because the raw material is cooked
with no addition of  steam or water  and because  the  moisture   in
the  material is removed from the cooker by evaporation.  It. is a
batch process because it follows the repetitive cycle of  charging
with raw  material,  cooking  under controlled  conditions,   and
finally  discharging of  the  material.   A  typical modern batch
rendering process   is  illustrated   schematically   in   Figure   3.
Although  only  one  cooker is shown,  the  usual installation will
have from three to ten cookers.

Before charging the  dry  batch  cookers,  the  raw material   is
usually  reduced  in size by crushers  (sometimes  called grinders,
prebreakers, or hoggers) to a  size of  one   to   two   inches   to
provide  for efficient cooking.  Cooking normally  requires  1.5 to
2.5 hours,  but may  run as long as  3.5  to 4 hours.  The  cookers
are  charged  with   raw  material by either a  screw conveyor or by
blowing  the material in  under pressure from  a  "blow  tank."   The
raw  materials  used are quite variable, depending on  the source,
and adjustments  in cooking  time, temperature,   and  speed   of
agitation   are usually required to properly  process the material.
For example,  shop fat and bone from butcher  shops   may  yield   37
percent  tallow  and have an initial  moisture  content of only 40
percent; dead beef  cattle, when  processed,   may   yield  only   12
percent  tallow  and have  an  initial moisture  content  of 63
 percent.   Then again, poultry feathers,  which  yield  no  grease,
 and  may  have an  initial moisture content of 75  percent, require
 cooking  under  pressure  (about 3.7  atmospheres or  40 psig) for  30-
 45 minutes in  a  batch cooker  for   hydrolysis,  prior  to  cooking
 under  normal  or   atmospheric  pressure   for an  additional 30-40
 minutes  to  reduce  the  rroisture  content   to  40-50   percent.
 Finally,  the  feathers   are  dried  in a  rotary  or ring dryer to
 reduce the moisture content to  5  percent.

 The general practice in  determining the end  point of the  cooking
 operation  is   by   previously   established  cook   cycles  and  by
 periodic withdrawal of  samples  by  the  operator to  determine  the
 consistency  by   touch  of the cooked material.  A less frequently
 used method is to  measure the moisture content  of  the  material
 with an electrical conductivity device,  but  this  approach has  not
 been  generally   successful;  it is ineffective when cooking blood
 or a variety of  other  materials.   Temperature is  used   to  follow
 the  progress   of   the   cooking.   The  temperature of the material
 being processed  remains  substantially  constant until the moisture
 level has dropped   to   5  to  . 10   percent.   At  this   point  the
 temperature begins  to  rise  rather  rapidly  and the cooking process
 should  then  be  stopped to  prevent product degradation and odor
 problems.    Throughout   the   cook,   the  jacket  stream  pressure
 usually  is  maintained  constant,  between  2.7 and 6.1  atmospheres
 (25 and 75 psig),  although a  few  use a pressure as great  as  7.8
 atmospheres (100 psig)  or a temperature of 170°C   (334°F).

 The  cooked  material   is discharged from  the batch cooker into a
 percolation pan  and let  stand until all free-draining  fat has run
 off.   The  solids are then conveyed  to  a   press    (usually  screw


                                 16

-------
Dead Stock Carcasses
       I
Shop Fat
and Bone
    RAW MATERIAL RECEIVING
                                 ENTRAPMENT SEPARATOR
                                         Exhaust Vapor
                                CRUSHER
                               Steam - 25-75 PS I •





•u


-r~i



(fir"!


II
COOKER
V fl
II /

                                     Jacket Condensate —/
                 PRECOAT
               LEAF FILTER
                                CENTRIFUGE
                              Solids to Screw Press
                                                             PERCOLATOR
                                                           — DRAIN PAN
                                Figure 3.  Batch Cooker Rendering Process

-------
press)   to  further  reduce the fat content.  Finally, the solids
are conveyed to grinding and screening operations.

Prior to ten years ago, essentially  all  inedible  rendering  at
independent  rendering  plants  was conducted using the dry batch
cookers.  In recent years,  however,  a  number  of  plants  have
replaced  batch  cookers  with  continuous  systems because these
systems  offer  inherent  advantages:  improved  product  quality
control;  better  confinement  of  odor and fat aerosol particles
within the equipment, thereby requiring less cleanup;  less space;
and less labor for operation and maintenance.   Also,  continuous
systems  permit  increased  throughput and occasionally result in
consolidation of two or more plants.  It is currently  estimated,
however,  that 75 to 80 percent of the plants still use dry batch
cookers.  The percentage of batch cookers is expected  to  continue
to decrease in the near future for economical reasons, but it  is
very   doubtful  that  it  will  ever  be  entirely  replaced  by
continuous systems.  This is because most small plants could  not
afford  continuous  sytems  and  because  some  materials such as
feathers and fclood are better handled in a dry batch system.


                       Continuous Systems

Continuous rendering systems, as mentioned above,  have   replaced
 some   batch  systems.   A  continuous  system  has the ability to
provide an uninterrupted  flow  of  material  and  to  produce  a
product  of  more  constant  quality-  In addition, the residence
time  in some continuous  systems  is  much  less  than in  batch
 systems,  ranging  between 30 and 60 minutes; as a result of less
exposure to heat,  product  quality  is  improved.   An   inherent
disadvantage  of   the  continuous system is that when  a component
breaks  down, the   entire  plant  is  shut  down.   Hence, it  is
important  that  a  thorough  preventive  maintenance  program be
rigidly followed to keep the plant in operation.

Unlike  batch systems, the manufacturers of continuous  systems  do
not   use  the  same  basic  design.  Currently there are  at least
three  major manufacturers of continuous  systems  being   used  by
independent  renderers.   These  three  companies  are the  Duke
continuous  system,  manufactured  by  the  Dupps  Company;   the
Anderson   C-G    (Carver-Greenfield)   system,   manufactured  by
Anderson-Ibec;  and  the  Strata-Flow  System   manufactured   by
Albright-Nell Co.


Duke Rendering System

The  Duke  System  was  designed  to  provide a method of cooking
similar  to  that  of  batch  systems  except  that   it   operates
continuously.   This  system  is  illustrated  in  Figure 4.  The
cooker, called the Equacooker,  is  a  horizontal  steam-jacketed
cylindrical  vessel  equipped  with a rotating shaft to which are
attached paddles that lift the material and move it  horizontally
through  the cooker.  Steam-heated coils are also attached to the

                                 18

-------
shaft to provide increased heat transfer.   The  Equacooker  con-
tains  three  separate compartments which are fitted with baffles
to restrict and control the flow of materials through the cooker.

The feed rate to the Equacooker is controlled  by  adjusting  the
speed of the variable speed drive for the twin screw feeder; this
establishes  the  production  rate for the system.  The discharge
rate for the Equacooker is controlled by the speed at  which  the
control wheel rotates  (see Figure 4).  The control wheel contains
buckets  similar  to those used in a bucket elevator that pick up
the cooked material from the Equacooker and discharge it  to  the
Dranor.  Next to the control wheel is located a site glass column
which  visually  shows  the  operating  level  in  the cooker.  A
photoelectric cell unit is provided to shut off  the  twin  screw
feeder when the upper level limit is reached.

The Drainor performs the same function as a perculator pan in the
batch  cooker  process.   It  essentially  is  an  enclosed screw
conveyor that contains a section of perforated  troughs  allowing
the  free  melted fat to drain through as the solids are conveyed
to the Pressor  or  screw  press  for  additional  separation  of
tallow.   The  Pressor  is  similar to any other screw press used
along with a batch cooker to  reduce  the  grease  level  of  the
crackling.

A central control panel consolidates the process controls for the
Duke  system.   The  control panel houses a temperature recorder,
steam pressure indicators, equipment speed settings,  motor  load
gages, and stop and start buttons, allowing one person to operate
the Equacooker part of the Duke system.


C-G  (Carver-Greenfield) Continuous System

The  C-G continuous process is of a considerably different design
than the Duke system.  Figure 5 is a schematic diagram of a  one-
stage  evaporator  C-G  system.  In the C-G system, the partially
ground raw material is fed continuously by a triple screw  feeder
at  a controlled rate to a fluidizing tank.  Fat recycled through
the C-G system at 104°C  (220°F) suspends the material and carries
it to a disintegrater for further size reduction—the final range
is from about one inch to 1/4-inch pieces.  This slurry  is  then
pumped  to  an  evaporator.   The  evaporator  can be a single or
double-stage unit, and is held under vacuum.  The  vacuum,  which
facilitates moisture removal, allows the C-G system to operate at
a  lower  temperature  than  some  other systems.  The evaporator
system is basically  a  vertical  shell-and-tube  heat  exchanger
connected to a vacuum system.  The slurry of solids and fat flows
by  gravity through the tubes of the heat exchanger  (evaporator),
while steam is injected into the shell.  The water vapor is  then
separated  from the slurry in the vapor chamber, which is under  a
vacuum of 660 to 710 mm  (26 to  28  inches)  of  mercury.   Water
vapor then passes through a shell and tube condenser connected to
a steam-ejection vacuum system.  The condensed vapors are removed
from the condenser through a barometric leg, which helps maintain


                               19

-------
                                  VAPOR CONTROLLER
   RAW
MATERIAL
   BIN
     MAGNET
        TWIN SCREW
          FEEDER
                     -a
    ENTRAINMENT
     SEPARATOR
                                                     Vapor Inlet
                                              Air
                                              Inlets
                     Pump
                              c
                              PU4
                                          Condensing Tubes

                                          Water Spray Nozzles
                                       Blower
                                               NON-
                                                                       Condensables
                                          INCIN-
                                         ERATOR
                                                          i i
                                                          I 0
                                                                   Condensate to Sewer
                          p  pin  nip  a
               CONTROL      Vent
                WHEEL
                         Fat
                        Drainer
      Steam to Coils

              EQUACOOKER
D
TUT1
D!D n!
D  D
                                       T
                                                                    CENTRIFUGE
                                          I          I
                                          I Solids     I
                                                                                  FAT
                                                      STORAGE

                                                   VARI-SPEED
                                                                                            Vent
         Steam to Jacket
                                                                                             Blower
                                                                                 Meal Cake to Grinding
                                                Press Fat
                              Figure  k.  Continuous Cooker - Duke Process

-------
the  vacuum in the system.  In the case of a two-stage evaporator
system, the vapor evaporated from the second stage  serves  as  a
heating  medium  for  the  first  stage.   Two-stage  evaporators
provide  steam  economy,  and  are  especially  useful  for   raw
materials  with a high moisture content.  The dried slurry of fat
and cracklings is then pumped from the evaporator to a centrifuge
which separates the solids from the liquid.  Part of the  fat  is
removed  from  the  system  at this point, while the remainder is
recycled back to the fluidizing tank.  The solids discharged from
the centrifuge are screw conveyed to  expellers   (screw  presses)
that  reduce  the fat content of the solids from about 26 percent
by weight to 6 to 10 percent.

A central control panel allows one operator to control the entire
cooking process.  Level indicators and controls are  provided  to
stabilize the flow through the fluidizing and other process tanks
and   also   for  the  vacuum  chamber.   Evaporator  vacuum  and
temperature are also monitored.  Equipment speed settings,  motor
current  readings and start/stop push buttons are also located on
this panel.


Strata-Flow Continuous System

The third  system,  ANCO-Hormel  Strata-Flow  continuous  system,
manufactured  by the Albright-Nell Company, is basically a series
of batch cookers stacked one above the other.  Normally  five  or
six  stages  are provided in series.  Each cooker stage is vented
to a common  manifold  that  is  connected  to  a  condenser  for
removing vapors.

The   crushed   raw   material   from  the  prebreaker  is  blown
continuously to the first stage cooker.   This  eliminates  screw
conveying  and  pumping of the raw material.  The cooked material
discharges from the last stage to a  percolation  pan  called  an
Autoperc.   A  drag  conveyor  located  in  this pan continuously
removes material after the free run fat has drained off.
                        EDIBLE RENDERING

Edible rendering is estimated to be conducted by  less  than  two
percent  of the independent renderers.7  However, these plants do
both edible and inedible rendering, and probably  less  than  one
percent  of  the raw material handled by independent renderers is
used for edible rendering.

Edible rendering of inspected fats can be conducted by  either  a
wet  or  a low-temperature process.  The wet process is conducted
in a vertical tank with injection of live steam under a  pressure
of  about  3.7  atmospheres  (40 psig) and a large volume of "tank
water," which should be evaporated.  The quality of the lard  and
tallow  thus  produced  is quite low.  For this reason, this once
common process  is  rarely  used  any  more  and  no  independent
rendering  plants  surveyed  in  this study use the wet rendering


                               21

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                                                         Water
rv>
ro
                                                                                    EVAPORATOR
              •+ DISINTEGRATOR
         PREBREAKER
                                          AFTER
                                        CONDENSER
                                                                                                       CENTRIFUGE
                                         VAPOR
                                        CHAMBER
          FLUIDIZING
             TANK
                                                                                Expeller
                                                                                 Vent
                                                                              Vent
                                                                              Discharge
                                                                               Pump
            Fluidizing pump
                                          Recirculation Pump
                                                                                                                         Expeller Cake
                                                                                                                         to Grinding
Recycle Fat at 200" Fahrenheit
                                                                          Recycle Pump
                     Expeller Fat
                                                                                                                        To Fat Storage
                                        lire 5 .   Corxtituj-ou-s  Cookeir "by  Carrie.!?  — Careen, field Process

-------
process.  Low-temperature rendering of fats is the most  commonly
used  method  for  edible  rendering.   Fats,  after being finely
pulverized in a grinder, are placed in a melter and heated  to  a
temperature  of  49°  to  82°C  (120° to 180°F) .  When the cooking
temperature  is  maintained  at  or  below  49°C    (120°F),   the
cracklings  or  solids  may  also  be  used as an edible product.
Cooking at these low temperatures  does  not  evaporate  the  raw
material  moisture.   Hence, after the fat has separated from the
solids and water in the melter, the cooked material is  desludged
by  screening or centrifuging.  The water phase is also separated
during desludging.  The remaining water entrained in the hot  fat
is  then  removed  in  a second centrifuge.  The separated water,
called tank water, can be further evaporated to a thick  material
known  as  stick,  which  can  be  used  as  tankage for inedible
rendering.

The general practice in either  wet  or  low  temperature  edible
rendering  is to directly sewer the tank water.  However, this is
a poor practice from a pollutional standpoint because tank  water
can  have  a  BOD5  of anywhere from 30,000 to 45,000 mg/18 and a
grease value as high as 20,000 to 60,000 mg/1.  If, instead,  the
tank  water  is  evaporated  and  the stick used for tankage, the
water waste load from wet-or low-temperature rendering  would  be
similar to that from a dry process.


               COOKER USES AND PROCESS VARIATIONS

The  type  of  inedible cooker chosen—batch or continuous—is in
some instances very dependent upon the material handled  and,  of
course, on the size of the plant.  Poultry feathers and hog hair,
for  example,  are handled in most plants in batch systems.  This
is because these materials must first be cooked under pressure of
about 4.4 atmospheres  (50 psig) to  hydrolize  the  proteinaceous
material   (primarily  keratin)  to  usable  protein  before being
cooked and dried in the same way as  other  materials  are  in  a
batch  system.   A  continuous processing system is now available
for materials that require hydrolysis, such as feathers, in which
the material passes through a hydrolyzer and then into a cooker.

Blood is another material  normally  handled  in  batch  cookers.
However,  in  some  cases,  the  final drying and conditioning of
blood, feathers, and hog hair is carried out in a ring or  rotary
dryer.   This  method of drying following batch cooking permits a
higher production rate for a plant with a given number  of  batch
cookers.   This is because of poor heat transfer during the later
stages of drying in batch cookers as the material passes  through
a  "glue  stage."   In  a  few cases, blood is processed by steam
sparging, which coagulates the  albumin;  then  the  albumin  and
fibrin  are  separated  from the blood water by screening and are
processed in a batch cooker or  ring  dryer.   The  blood  water,
which can have a BOD5 up to 16,000 mg/1, is usually sewered.

The  ring dryer system, as the name implies, is in the shape of a
flattened  ring  or  race  track,  positioned  vertically.    The


                              23

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material  to be dried  is  first  pulverized  and then  blown into the
ring where it is conveyed around  the  ring  by   furnace  gases  of
314°  to 425°C  (600° to 800°F).   Centrifugal force,  recirculation
rates, and control dampers permit  the   material to  recirculate
until  the  particles  of  the  material become light  enough because
of drying to escape along with  the  exhaust  gases.   A  cyclone
separates the material from the exhaust gases,  which are conveyed
away  by an exhaust fan.   This  exhaust  fan is necessary to ensure
a slight negative pressure in the ring  dryer and thus to  prevent
material  from  leaking out of the dryer.  The high  temperature of
the furnace  gases  can   cause  scorching   of   the   proteinaceous
material,  resulting   in  strong odors.   Consequently, the exhaust
gases are frequently ducted through a spray  scrubber.

Rotary  (air) dryers are also  used to further dry blood,  feather
and   hoghair meals.  The  dryer  is a horizontal  cylindrical vessel
equipped with longitudinal steam  tubes.   The   material  cascades
through the dryer as it rotates.   Rotary dryers create less of an
odor  problem   than ring  dryers because of the  lower temperatures
involved and the lower volumes  of air required  for  drying.
                         VAPOR CONDENSING

 Cooking vapors from dry batch processes and also from evaporating
 tank water are condensed by one  of  three  methods:   barometric
 leg,  air condenser,  and shell-and-tube heat exchanger.  Prior to
 five or ten years ago,  all vapors were condensed with the use  of
 a barometric leg.

 In  a  barometric  leg,  the  cooking  vapors  are contacted with
 condensing waters and together flow gravimetrically out through a
 standpipe.  A barometric leg  condenser  is  basically  a  water-
 powered  ejector  located  on  top  of  a standpipe.  As the high
 velocity water passes through the ejector, it creates a vacuum on
 the downstream side.   The vacuum draws the  cooking  vapors  into
 the   high  velocity  water  where  the  vapors  are  cooled  and
 condensed.  The vacuum is usually very slight for batch  cookers,
 whereas  for  several  continuous  systems  using  barometric leg
 condensers the vacuum may be quite high, thus  requiring  a  long
 standpipe.    The  standpipe  serves  two  purposes.   First,  it
 provides  a  confined  space  for  contact  between   the   vapor
 condensing water.  Second, it acts as a reverse water trap.  This
 prevents   condensed   vapors   and  cooling  waters  from  being
 accidentally sucked back into a sealed cooker as  it  cools.   To
 ensure  against  back-up  even under a nearly perfect vacuum, the
 standpipe should be slightly over 10 meters  (33 feet) high.  This
 is because a one-atmosphere vacuum can lift water to a height  of
 only  about 10 meters.   In general, it was observed that very few
 barometric leg condensers used in the industry are near  33  feet
 in  height.    However,   a few plants with barometric legs protect
 against  back-up  by  installing  an  air  check  valve  in   the
 standpipe.   Hence,  before a vacuum can lift water to the top of
 the standpipe, the air valve will open and reduce the vacuum.
                               24

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Air condensers and shell-and—tube  heat  exchangers  are  rapidly
replacing   the  barometric  leg  for  condensing  water  vapors.
Probably the major reason for this is  that  air  condensers  and
shell-and-tube  heat  exchangers  do not dilute the waste waters.
Barometric legs, on the  other  hand,  highly  dilute  the  waste
waters  resulting  from  the  condensing  of  vapors.   Usually a
barometric leg is used on each batch cooker, and each requires 57
to 151 liters   (15  to  40  gallons)  per  minute  of  water  for
condensing.   In  plants  that  are  continuing to use barometric
legs, the trend is to recycle treated or partially treated  water
through the barometric leg.

Air  condensers  force  ambient  air  across a bank of externally
finned tubes.  A typical unit has a horizontal section containing
finned tubes, a steel supporting structure with  plenum  chambers
and  fan  ring, axial-flow fan, drive assembly, and miscellaneous
accessories such as louvers, fan guards, and temperature-operated
fan speed controls.

Shell-and-tube heat exchangers are basically cylindrical  vessels
containing a bundle of parallel tubes.  The tubes are enclosed in
such  a manner that they isolate the liquid inside the tubes from
the liquid surrounding the tubes.  Normal flow arrangement is  to
have  the  condensate  inside  the  tubes.   The cooling water is
recirculated through  a  cooling  tower  to  dissipate  the  heat
collected   in   condensing   the   cooking   vapors.   Water  is
continuously added to the cooling water to make up for that  lost
by evaporation.
                   GREASE AND TALLOW RECOVERY

Grease and tallow recovery is normally accomplished in two steps.
The  first  step  is  draining  in percolation or drain pans just
after the material is dumped or removed from cookers.  For  batch
systems,  the  material  may  be  allowed  to drain for up to two
hours.  This normally reduces the fat content of the solids to 25
percent.  The second step in fat reduction involves the  pressing
of  solids  to  reduce  the  residual  tallow  content to 6 to 10
percent.  The usual practice is to use a screw press to allow for
continuous throughput, although some  small  or  old  plants  may
still  use  hydraulic  batch-operated  presses.   The screw press
consists of a cylindrical barrel of metal bars  that  are  spaced
with  narrow  openings  between  to  allow the fat to be squeezed
through by the action of a rotating screw.  Hence,  the  pressure
within  the  screw  press  is  maintained by friction and the fat
present in the solids  provides  a  lubricating  effect.   It  is
important  that  overpressing  of  the  tallow from the solids be
avoided;  otherwise  overheating  and  scorching  can  result  in
producing   smoke   and  strong  odors.   Frequently,  the  smoke
generated by screw presses  is  drawn  through  an  odor  control
system that uses either wet scrubbing or incineration.

In  possibly one percent of the plants, the second step in grease
and  tallow  reduction  involves  solvent  extraction.   In  this


                             25

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process  a  solvent  such  as hexane is used to remove the  excess
grease.  Heat is then required to separate the solvent   from   the
grease  and  to  remove  it  from  the  solids.   The  solvent is
recovered for recycle.   This  process  reduces  the  tallow   and
grease  content  of  the  solids  to  one  percent  or less.   The
increased income derived from the  additional  fat  recovered   by
solvent  extraction,  however,  is usually too small to  encourage
widespread use of solvent recovery.

Tallow and grease recovered in the  two  steps  of  drainage   and
pressing  are normally combined and then further clarified.  This
usually  involves  screening,  centrifuging,  or  filtering,    or
combinations  thereof.   Solids  recovered from clarification  are
returned to the cracklings prior to the second step of tallow  and
grease recovery.  The tallow and  grease  are  then  pumped into
storage tanks and held for later shipment.


                        SOLIDS PROCESSING

The  solid proteinaceous material discharged  from the screw  press,
known as   cracklings,  is  normally  screened  and ground  with a
hammer mill to  produce a meat and bone meal  product  that  passes
through   a  10- to  12-mesh screen.  The finely divided solids  are
usually  stored  in   bulk  handling  systems   for  later   shipment.
Occasionally  this material is blended with another, such as blood
or  feather   meal,   to  ensure  a  high  level  of crude protein.
Frequently, the blood and/or feather meal  are  bagged   prior   to
shipment,   although this operation is normally a relatively small
one.
                           ODOR  CONTROL

 Odor control  is  practiced  in  nearly  all  rendering  plants  today.
 Although  rendering  odors are  not necessarily harmful to health,
 they may be very offensive to people because  of  their  distinct
 nature  and   the  complexity  of  the odor  compounds present.   A
 recent study9  identified a number of odorous compounds present  in
 rendering plant  emissions.  The important categories of compounds
 identified were  sulfides,  amines, aldehydes,  ketones,  alcohols,
 and  organic   acids.   The  major methods  of odor control basically
 involve  using  scrubbers   with or   without   chemical   oxidant
 solutions   (the   most    commonly    used   chemical   is  sodium
 hypochlorite) ,   and  incinerators.    Condensers  and  temperature
 control  of   cooking   vapors  involve rendering plant operations
 which  should  be  adequately  controlled to   minimize   odors.
 Excellent discussions of the control  of  odors from inedible
 rendering plants can  be found in references  2 and 10.

 The primary sources of odor are from  the cooking  and  pressing
 operations because,   in   both  cases,   the  material is heated to
 temperatures  of  105°C (220°F) or  higher.   Of  course,  aged  or
 deteriorated   raw   materials   will appreciably  increase  the
 intensity of  odors from these operations.   Furthermore,  if  the


                                26

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raw  materials are not particularly fresh, it may be necessary to
control this odor source by covering screw conveyors and  venting
them to the odor control system.

The  condenser  plays  a very important part in controlling odors
from cookers.  One of the best ways of controlling any odors from
the cookers is to  ensure  that  the  final  temperature  of  the
condensed  cooking  vapors  is  below 52°C (125°F), or preferably
below 38°C (100°F).  In addition, the noncondensable vapors  from
the cooker, which give high-intensity odors,  can be controlled by
venting  directly  to  the  boiler  used for generating the plant
steam.  This is feasible only under  certain  circumstances.   If
the  odorous  stream  is  used  as  primary  combustion  air, the
necessary precautions must be  taken  to  remove  solid  and  fat
aerosol  particles before passing this air through the boiler and
controls.  Also, the boiler must be equipped with suitable burner
controls to ensure that the minimum firing rate is sufficient  to
incinerate the maximum volume of effluent gas passing through the
boiler  firebox,  regardless  of  the  steam requirements.  Press
odors are treated by venting these vapors through a  scrubber  or
incinerator.   The  intensity  of  the  smoke  and  odor from the
presses is occasionally high  enough  that  the  scrubbing  water
cannot be recycled.

Using  water  without  chemicals  in  a scrubber usually does not
permit high recirculation rates, and thus  requires  large  water
use;  the  effect  is  that  the  waste waters from the plant are
diluted.  When chemicals such as sodium hypochlorite are used, it
is normal to recycle up to 95 percent  of  the  scrubber  waters;
this minimizes chemical and waste water treatment costs.  Wasting
five percent of chemical scrub water should not affect either the
volume  of  the waste water or its treatability to any noticeable
degree.

Direct-fired incineration units could be used anywhere  in  place
of  the  scrubber,  although they are normally used only for low-
volume high intensity odors.  However, in recent months, the  use
of  incinerators  has  been  reduced  drastically  because of the
difficulty in obtaining the necessary fuel.   Even  before  there
was  difficulty in obtaining fuels, scrubbers were believed to be
the most economical method of odor control.9
                       WASTE WATER SOURCES

Waste waters from the rendering  of  raw  materials  contain  the
condensate or moisture evaporated from the raw materials and wash
water  from  cleaning  the  plant  and  the  raw materials pickup
trucks.  In some  cases,  the  waste  water  contains  additional
condenser  water and liquid drainage from the raw materials.  The
strength of these waste waters, which contain  organic  materials
including   soluble  and  insoluble  protein,  grease,  suspended
solids, and inorganic materials, can be greatly  increased  as  a
result  of  run-down and poorly maintained equipment.  Also, poor
housekeeping practices can result in accidental spills of raw and


                              27

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finished materials into the waste waters and the  foaming  over  of
material from the cookers.

Trucks  and  barrels  used  for  picking  up  raw  materials   are
carefully washed after each use.  The  amount of   water  used   for
this  is  probably  insignificant,   although these  operations can
contribute significantly to the waste  load, particularly   to   the
grease  load.   Barrel  washing,  however,  is   not  as  common a
practice as it once was in rendering plants, since   most   barrels
are emptied at the pick-up site and  are not brought to the plant.
Barrels are primarily used to transport restaurant  grease.

Washdown  in inedible rendering plants is not nearly as intensive
as it is  in  meat  processing  and  packing  plants.    In fact,
washdown  usually  occurs  at  the   end of a day's  operation  when
rendering has  been  completed.   Normally  only the  areas   for
receiving,  grinding and cooking of  raw materials and the product
separating and grinding areas are washed down.   The  other areas
of  the  plant  are  generally  dry  cleaned.  Washdown does occur
within the plant, however, whenever  there is an  accidental spill.
Washdown of  accidental spills without  prior dry  cleanup obviously
adds  significantly to the  waste  load from  inedible  rendering
plants.   The  most  common accidental spills observed, that  were
entirely cleaned up by  washdown,  were  of  tallow  and  grease.
Fortunately,   a  properly  operated  materials   recovery  system
 (primary or  in-plant treatment) can  recover a  large  portion  of
these materials  for recirculation to the cookers.
                        MATERIALS  RECOVERY

 Materials   recovery   from  the  waste  water streams (primary or in-
 plant  treatment)  is  conducted   in  essentially  all  rendering
 plants.    The   most   common  materials  recovery  system  used by
 independent renderers  is  a   catch   basin  or  skimming  device.
 Basically,   this   device   is   a   large  rectangular  tank  in the
 effluent stream to allow grease and  oil to float to  the  surface
 and solids  to  settle  to the bottom,  thus separating them from the
 waste  water.   Grease  and oil that  float to the surface in catch
 basins  are  normally removed manually once  or  twice  a  day  and
 blended in  with the raw materials for recycling, or are processed
 separately.    With automatic  skimming devices, the materials may
 be collected for  recycle once  or  twice  a  day  or  they  may  be
 continuously  recycled  using  screw  conveyor  systems.   Solids
 collected   from  catch  basins are   less  frequently   recycled;
 however,    it   is   becoming   more  common  practice  today  to
 occasionally  pump out solids   and  recycle  them  through  the
 rendering  equipment.

 Some rendering  plants  (15   out of  49  plants included in the
 survey)  have air  flotation systems in place of  catch  basins  or
 skimming devices.    However,  these  systems  are  normally  not
 operated under optimum  conditions for either  materials  recovery
 or  waste water treatment.  Optimum  conditions might require flow
 equalization,  pH  control,  temperature control, and  the  addition


                               28

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of  chemical  flocculating  agents.  The temperature of rendering
plant waste waters is often somewhere between 70° and 85°C   (125°
and 150°F), which is too high for effective grease removal by air
flotation  systems  or  by  other gravity separation methods.  At
these temperatures, grease  is  too  soluble  in  water  for  the
required  phase  separation.  Further, chemicals are not normally
added to the air flotation system because  the  resulting  sludge
collected  would  be  very  high in water (85 to 95 percent)  and,
consequently, this excess water would  add  considerably  to  the
heat  load  if  recycled  through  the  cookers.  The addition of
chemicals could also change the nature of  the  grease  and  thus
lower  its  market  value.   One  solution to this is to have two
materials recovery systems in series, where the second one is  an
air flotation device to which chemicals have been added.
                HIDE CURING  (ANCILLARY OPERATION)

Hide  curing  occurs in a number of rendering plants, essentially
as  a  separate  operation  from  rendering.   In   many   cases,
slaughterhouses   and  packinghouses  from  which  the  renderers
collect their material are either too small to handle hide curing
or do not have the necessary equipment.   Consequently,  for  the
renderer  to  obtain these sources as users of his "services," he
must also pick up the hides along with  his  raw  materials.   In
addition,  many  rendering plants handling a large number of dead
animals will find it economically favorable to remove  the  hides
from dead carcasses for curing.

The  older  method of curing hides was to dry pack hides in salt.
However, in recent years the  trend  has  been  to  replace  this
operation   with   brine   curing  in  raceways  Or  brine  vats.
Essentially, the hide curing is a dehydration process, and in the
brine-wring process there results a net overflow of approximately
two to three gallons cf brine cure for each hide handled.   These
wastes  are  nearly  saturated  with  salt and also contain other
dissolved solids plus blood, tissue,  and  fats  and  oils.   The
overall  contribution  of  this  waste  load  to  that  from  the
rendering plant is usually relatively  small.   However,  a  high
salt load can cause probleirs in the treatment of the waste waters
and  in  some  cases  may  make  it very difficult for a plant to
obtain a final chloride content that would meet  some  state  and
local  regulations.  A possible solution to this problem might be
to blend the curing effluent with the raw material as it enters a
dry cooker.
                               29

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                           SECTION IV

                     INDUSTRY CATEGORIZATION


                         CATEGORIZATION

In developing effluent limitations guidelines  and  standards  of
performance  for  the  independent rendering industry, a judgment
was made as to whether limitations and standards are  appropriate
for  different  segments  (subcategories) within the industry.  To
identify any  such  subcategories,  the  following  factors  were
considered:

     o     Waste water characteristics and treatability

     o     Raw materials

     o     Manufacturing processes  (operations)

     o     Processing equipment

     o     Size, age, and location of production facilities.

After considering all of these factors, no justification could be
found  for  dividing  the  industry  into  subcategories.  Hence,
independent rendering constitutes only one subcategory,  and  the
effluent  limitations and standards of performance recommended in
this report are intended to apply to  all  independent  rendering
plants except those processing fish by-products.

An  independent  rendering  plant is one that collects animal by-
products such as bone, offal, fat, and  dead  animals  from  such
sources  as  slaughterhouses,  processing  plants, butcher shops,
restaurants, feed lots, and  ranches,  and  processes  them  into
products  such  as fats, oils, and solid proteinaceous meal.  The
products may be either edible  or  inedible.   Plants  processing
fish  by-products  are  not included in this study.  In addition,
rendering  plants  that  are  an  adjunct  to  meat  and  poultry
operations  and are located on the same premises are not included
in  the  category  of  independent  renderers.   An   independent
rendering  plant  may  also cure hides as an ancillary operation.
The manufacturing processes in an independent rendering plant are
shown in Figure 6.

                  RATIONALE FOR CATEGORIZATION

          Waste Water Characteristics and Treatability

Basic processes in independent rendering plants  are  essentially
the same, although such factors as equipment type, raw materials,
and size and age of the plant may differ.  Hence,  it was possible
to  consider  division  of  the  industry  on  the basis of these
factors which might group plants with  similar  raw  waste  water
characteristics.    The   waste   water  characteristic  used  in
                              31

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             BASIC PROCESSES
                     ANCILLARY PROCESS
              RAW MATERIAL
                RECEIVING
              CRUSHING AND
                GRINDING
              COOKING AND
                 DRYING
                 PRODUCT
                SEPARATION
MEAL GRINDING
AND SCREENING
  GREASE
CLARIFYING
  BLENDING
  STORAGE
   STORAGE
                              SHIPPING
   SHIPPING
                                                      HIDECU(RING
              Figure 6.  Manufacturing Processes of a Rendering.Plant
                                 32

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attempting to categorize  (subdivide) the industry was  the  5-day
biochemical  oxygen  demand   (BOD5)  in  units per 1000 units raw
material (RM) handled or processed:  kg BOD5/kkg RM  (Ib BOD5/1000
Ib RM) .  BOD5 provides the best measure of  plant  operation  and
treatment  effectiveness  among  the parameters studied, and more
data  are  available  than  for  all  ether   waste   parameters.
Suspended  solids, grease, and COD data serve to substantiate the
conclusions developed from using BOD5 in characterizing both  the
industry  and  the  raw  waste   (Section  V).   The raw waste was
evaluated and is herein discussed as that waste water  discharged
subsequent   to   materials  recovery  operations—catch  basins,
skimming tanks, etc.

The major plant waste load is organic and  biodegradable:   BOD5,
which  is  a  measure of biodegradability, is the best measure of
the load entering the waste stream from the plant.   Furthermore,
because  secondary  waste treatment is a biological process, BOD5
also  provides a useful measure of the treatability of  the  waste
and   the effectiveness of the treatment process.  Chemical oxygen
demand  (COD)  measures total organic content  and  some  inorganic
content.   COD is a good indicator of change, but does not relate
directly to biodegradation, and thus does not indicate the demand
on a  biological treatment process or on a stream.

A number of additional parameters were also considered for use in
categorization besides BOD5, suspended solids,  grease  and  COD.
Among  these  were  nitrites  and  nitrates,  Kjeldahl  nitrogen,
ammonia, total  dissolved  solids,  total  volatile  solids,  and
phosphorus.   In  each  case,  data  were insufficient to justify
categorizing on the basis of the  specified  parameters;  on  the
other  hand,  the  data  on these parameters helped to verify the
judgments based on BOD5.

Judging from secondary waste treatment  effectiveness  and  final
effluent  limits,  waste  waters from all plants contain the same
constituents and are amenable to the  same  kinds  of  biological
treatment  concepts.   Geographical  location, and hence climate,
affects the treatability  of  the  waste  to  some  degree.   All
biological   activity   slows   at   lower  temperatures;  hence,
biological waste treatment systems do not perform as well in  the
winter  months  in  northern areas as they do when the weather is
warm.  Climate has occasionally influenced the kind of  secondary
waste  treatment used.  However, the ultimate treatability of the
waste or the treatment effectiveness can  be  maintained  at  the
highest  levels  by  not discharging during the coldest months of
the year.  The time  period  for  no  discharge  will  vary  with
location,  but  should never exceed six months.  This is the same
practice that is used by plants that dispose of their waste water
by irrigation.

In the following parts of this section,  the  factors  that  were
considered  in  categorizing  the  industry  for the basis of raw
waste water characteristics are examined.
                             33

-------
                          Raw Materials

No clear relationship of direct   statistical   dependence  between
kind  of  raw  material and raw BOD5  waste load could be found by
statistical (multiple regression)  analysis.   As a result, a clear
independent relationship was disclosed  that   all  types  of  raw
materials  may  be expected to result in similar BOD5 discharges.
In addition, the range  (low and high)  and average of  BOD5  waste
water  values  for  plants  processing  greater  than  50 percent
poultry by-products could not be  differentiated from those plants
processing less than 50 percent poultry  by-products or from those
for the total industry.  This is  illustrated   by  bar  graphs in
Figure  7.   Hence,  the type of  raw  materials processed is not a
meaningful factor for categorization.

Animal by-products were classified for  the  multiple  regression
analysis as:

     o     Packinghouse  (slaughterhouse)  materials which are
           primarily animal offal

     o     Shop fat and bones

     o     Grease

     o     Blood

     o     Dead animals

     o     Poultry offal

     o     Feathers and hair

The  multiple  regression  analysis correlated the percent of raw
material  in each of these  classes with the raw BOD5 load for each
set  of data.  A total of  45 sets  of data  were  included  in  the
analysis,  representing   information on 29 independent renderers.
There were several sets of information,  up to three, for a number
of these  plants.  The sources of  this information were  voluntary
questionnaires distributed by the National Renderers Association,
supplementary data supplied by the companies  such as reports from
consulting  firms,  and the results of our field sampling survey.
Some questionnaire data represent the  average  of  data  over  a
period  of several months; other  data represent grab or composite
values over short periods  such as a day or two.   The  result  of
the  regression  analysis  is  best  indicated  by  the  multiple
correlation coefficient.   This turned out to be 0.39.  The square
of this number, or 0.16,  is a measure of  the  predictability  of
the  change in BOD5 load  caused by a change in raw materials.  In
other words, 16 percent of a BOD5 load change could be  accounted
for  by   a  change  in  raw materials.  For the dependence between
animal by-products and  BOD5 load  to be
significant, the square of the multiple  correlation  coefficient
should  be greater than  0.5.  The lack of dependence between  BOD5
load and  raw materials  is  somewhat  surprising  since  the  raw


                             34

-------
CO
en
       CC
       LD
       Q
       O
       m
            6.00
           5.00
            4.00
3.00
            2.00
           1.00
                 (29)
                                                   (25)
                                                        -MAXIMUM
                                                                          (4)
                                            -AVERAGE
                                                        -MINIMUM
                            TOTAL
                          INDUSTRY
                                      < 50%
                                    POULTRY
                                   BY-PRODUCTS
   2 50%
 POULTRY
BY-PRODUCTS
                               Figure 7.   Average and Range of  BOD5^ Data by Raw Material Type

-------
materials  in each of the classes have  different initial moisture
contents and product yields of solids and  of  tallow  and  grease.
But then a simple regression analysis between BOD5  load and waste
water  flow,  both  expressed  in   units   per  1000  units of raw
material processed, also  did  not  reveal a  correlation.    The
correlation coefficient for this analysis  was -0.027.


                     Manufacturing  Processes

The  manufacturing  processes in independent  rendering were shown
in Figure 6.  Those processes considered as basic—raw  materials
receiving,  crushing  and  grinding,  cooking and drying, product
separation, meal grinding and blending,  grease  clarifying,  and
storage  and  shipping—are  conducted  in most plants.  In a few
cases, such as plants processing poultry   byproducts   (offal  and
feathers mixed together), the only  product is meal, and no grease
is   separated  and clarified.  These plants may have more complex
meal grinding and  screening processes.  The net result, based  on
field  survey results, was that the basic  manufacturing processes
were found to further reiterate the single subcategory conclusion
first discovered when analyzing raw materials.

The  ancillary manufacturing process (hide  curing),   however,  can
contribute  additional waste to the plants' raw effluent when the
waste load is only based upon the amount of raw material used for
the  basic manufacturing processes,  as it is in this report.    But
to   create  a  separate category for independent rendering plants
that cure hides would not result  in  a separate  set  of  fixed
effluent  standards.   This  is because the additional waste load
caused by hide curing is dependent  on the  relative amounts of raw
materials processed in  the  basic  and ancillary  manufacturing
processes.

The  best  way  of  accounting  for the additional raw waste load
caused by hide curing, therefore, is by the use of an  adjustment
factor.   The  adjustment  factor for hide curing is presented in
detail in Sections IX and X.  In summary,  then, the manufacturing
processes, basic and ancillary, were  not   considered  meaningful
factors for categorization.
                       Processing  Equipment

The processing  equipment  considered as factors for categorization
were   the   type of  cookers—batch versus continuous—and the type
of condensers used  for condensing cooking vapors—barometric leg,
shell-and-tube,  and air condensers.    Other  types  of  equipment
such   as grinders,  presses, etc., were not considered because the
basic  operating principles were generally quite similar for  each
type   of  equipment,   regardless  of the manufacturer, and because
the contribution to the waste  water load from  the  use  of  this
equipment was not significant.
                              36

-------
          6.00
                            (29)
          5.00
          4.00
to
      cc
      o>
if)
Q
O
00
          3.00
           2.00
          1.00
                                                  (17)
                                                      -MAXIMUM
                                                                                               (5)
                                                                        (4)
                                                       -AVERAGE
                                                       -MINIMUM
                          TOTAL
                         INDUSTRY
                                           BATCH
                                          SYSTEMS
  DUKE
SYSTEMS
   C-G
SYSTEMS
                                Figure 8.  Average and Range of BOD5_ Data  by Cooker Type

-------
           6.00
                               (29)
           5.00
           4.00
to
oo
     cc
 en
^
 if)
Q
O
00
           3.00
           2.00
           1.00  —
                                                                                                    (5)
                                                   (6)
                                                            -MAXIMUM
                                                                                (14)
                                                            -AVERAGE
                                                            -MINIMUM
                             TOTAL
                           INDUSTRY
                                             BAROMETRIC
                                              CONDENSER
SHELL & TUBE
 CONDENSER
AIR-COOLED
CONDENSER

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       Table 5.  Raw Waste Data on Rendering Plants by Equipment Type

Parameter
BOD5
kg/kkg RM
(lb/1000 Ib RM)




SS
kg/kkg RM
(lb/1000 Ib RM)





Grease
kg/kkg RM
(lb/1000 Ib RM)




Equipment
Type*
Total
Batch
Duke
C-G
Baro
S & T
Air

Total
Batch
Duke
C-G
Baro
S & T
Air
Total
Batch
Duke
C-G
Baro
S & T
Air
Number of
Observations
29
17
4
5
6
14
6

26
14
4
5
3
14
5
16
9
2
5
2
9
4
Average
Value
2.15
2.31
1.92
1.56
2.10
1.78
2.42

1.13
1.06
1.54
0.97
1.79
0.98
0.56
0.72
0.44
1.66
0.90
2.09
0.55
0.41
Standard
Deviation
1.34
1.34
0.99
1.97
1.39
0.95
2.00

1.39
0.91
2.44
1.87
2.20
1.44
0.65
1.14
0.48
1.82
1.83
2.96
0.96
0.43
High
Value
5.83
5.83
3.15
4.83
4.83
3.64
5.83

5.18
3.33
5.18
4.32
4.32
5.18
1.45
4.18
0.92
2.94
4.18
4.18
2.94
1.07
Low
Value
0.10
0.72
1.07
0.10
1.20
0.10
0.72

0.03
0.03
0.05
0.06
0.39
0.05
0.03
0.00
0.00
0.37
0.04
0.00
0.04
0.04
*Values listed as:
     •   Total represents the summary of combined data, regardless of equipment type.

     •   Batch, Duke, or C-G summarizes the results of the data from plants with
         batch, Duke and Carver-Greenfield cookers, respectively.   See Section III
         for a discussion of these cookers.
     •   Baro, S & T, or Air summarizes the results of plants with barometric leg,
         shell and tube, or air condensers.
                                    39

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Table  5  summarizes  the raw waste  data on independent rendering
plants using various kinds of cookers  and  condensers  for  BOD5,
suspended  solids,  grease,  flow,   and  amount  of raw materials
handled.  The data for the total industry are included in Table 5
for comparative purposes.  Figures  8 and 9 graphically illustrate
the average and range of the BOD5   data  from  Table  5  for  the
various  cookers  and  condensers,  respectively.   These data show
that there are no distinct raw waste water load differences  when
the data are grouped by the types of cookers and condensers used.
Thus,  it  was  concluded  that  the  factor of process equipment
proved consistent with findings regarding  manufacturing  process
and  substantially  supported  reasoning  to  designate  a single
category for the rendering industry.


        Size, Age, and Location of  Production Facilities

Size, age, and location are not meaningful factors for developing
subcategories.  Size as  a  factor   was  evaluated  by  a  simple
regression analysis between raw BOD5 waste load and the amount of
raw  material  processed per day using the data collected in this
study.   This  analysis  revealed   no   discernible   relationship
between BOD5 waste load and size, as measured by the daily amount
of   raw  materials  processed.  This is indicated by the value of
the  correlation coefficient, which  was 0.062.   It  is  necessary
that  a  correlation  coefficient value greater than 0.5 exist to
establish a meaningful correlation.    The  same  data  were  also
separated  into three data groups based on amount of raw material
used.   The data groups represented  approximately equal numbers of
plants.  Analysis of the data in each  of  the  groups  showed no
correlation  of plant size with BOD5 waste load.   Figure 10 shows
the  average and range values of BOD5 for the  three  size  groups
and  for all the plants included in  the study (indicated in Figure
10 by total).

Age  is often reflected by the type of processing equipment used.
Plants  over ten years old were  originally  equipped  with  batch
cookers  and barometric leg condensers.  However, in recent years
some older plants have replaced  batch  systems  with  continuous
systems  and barometric leg condensers with air or shell-and-tube
condensers.  Newer plants use both  batch and  continuous  systems
and  also  use  shell-and-tube and  air condensers more frequently
than barometric legs.  Therefore, the  major  difference,  from a
raw  waste load standpoint between  old and new plants is the type
of processing equipment.  Since processing  equipment  served to
indicate  a  single  discrete  category,  the  close  correlation
between age of facilities and equipment means that age  helps to
reiterate this conclusion.

Examination  of  the  raw waste water  characteristics relative to
plant location reveals no apparent  relationship or pattern.   The
type  of  animal by-products processes is soiretimes influenced by
location, but as mentioned previously, the type of  raw  material
processed had no discernible effect on raw waste.
                             40

-------
 in
 D
 O
 m
     6.00 —
     5.00 —
     4.00
     3.00
     2.00
     1.00
                    (29)
                  TOTAL
                  INDUSTRY
                                                            (10)
                                         (8)
                                            -MAXIMUM
                                            -AVERAGE
                                            -MINIMUM
                                                                                (11)
  <45,000  kg
(<100,000  Ib)
  45,000-114,000  kg
(100,000-250,000  Ib)
'114,000 kg
>250,000 Ib)
                               Plant Size:  kg (Ib) of Raw Material
Figure  10.   Average and  Range of  BODs  Values for  Three Size Groups of Plants
              and for All  Plants Studied (Total)

-------
                            SECTION V

              WATER USE AND WASTE CHARACTERIZATION


                   WASTE WATER CHARACTERISTICS

Water  is  used  in the rendering industry for condensing cooking
vapors, plant cleanup, truck and barrel  washing,  odor  control,
and  for  boiler  makeup  water.   The  principal  operations and
processes in rendering plants where waste water originates are:

     o    Raw material receiving

     o    Condensing cooker vapors

     o    Plant cleanup

     o    Truck and barrel washing

Waste  waters  from  rendering  plants  contain  organic   matter
 (including  grease),  suspended  solids,  and inorganic materials
such  as  phosphates,  nitrates,  nitrites,  and   salt.    These
materials enter the waste stream as blood, meat and fatty tissue,
body  fluids,  hair,  dirt, manure, hide curing solutions, tallow
and grease,  and  meal  products   (such  as  meat,  bone,  blood,
feathers,  hair  and  poultry  meal),  and  caustic  or  alkaline
detergents.


                    Raw Waste Characteristics

The raw waste load characteristics from  the  rendering  industry
discussed  in the following paragraphs include the effects of the
materials  recovery  process   (considered   the   primary   waste
treatment system such as catch basins and skimming tanks).

The  parameters  used  to  characterize the raw effluent were the
flow, BOD5, suspended solids (SS), grease,  COD,  total  volatile
solids   (TVS),  total  dissolved solids  (TDS), Kjeldahl nitrogen,
ammonia,  nitrates,  nitrites,  chlorides,  and  phosphorus.   As
discussed  in  Section  IV,  BOD5  is  considered  to be the best
available measure of the  waste  load.   The  parameter  used  to
characterize  the  size  of  the operations was the amount of raw
materials  processed.   All  values  of  waste   parameters   are
expressed  as  kg/kkg  of  raw materials  (RM), which has the same
numerical value when expressed in lb/1000 Ib RM.  Amount  of  raw
materials processed is expressed in units of kkg RM.

Table  6 summarizes the plant and raw waste water characteristics
for the single category of  independent  rendering  plants.   The
summary  includes averages, standard deviations, ranges  (high and
low values), and number of observations  (plants).
                               43

-------
The data used to compute the values presented   in  Table  6  were
obtained  through  questionnaires distributed  to their members by
the National Renderers Association  (NRA),   through  supplementary
data  submitted  by  the  companies   (such  as  laboratory analysis
reports and consulting  engineers'  reports) ,   and  through  data
obtained  from the field sampling survey conducted by North Star.
Questionnaires provided information on  49   plants;  12  of  these
were  also  included  in  the  field  sampling survey.  Two other
plants that did not  submit  questionnaires were  also  sampled.
Thus,  the  total number of plants included in this study was 51,
or about 11 percent of the industry.  Note, however,  that  data
were  not  available for all plants for all pertinent parameters;
thus, the number of observations  used   to   develop  averages or
other  characteristics  may  not conform to the sample total even
for such  parameters  as  waste  water   flow  or  pounds  of  raw
materials   processed.   The  data  in   Table   6  for  flow,  raw
materials, BOD5, suspended solids, and  grease  are primarily based
on questionnaire data; data on the other variables  were  largely
based on supplementary and field sampling information.  Note also
that  while  the  sampling  data generally  verified questionnaire
information, a number of atypical conditions esixted for four or
five  plants during the field visits  which  clearly caused unusual
results for raw waste loads.  The conditions included spills from
cookers, emergency use of  old  equipment,   and  malfunctions of
certain   in-plant   controls.   Thus,   the general  waste  load
characteristics  (for BOD5, TSS) were  derived from submissions by
the industry itself.


                    Discussion of Raw Wastes

The  data  in  Table  6 cover a waste water flow of 467 to 80,936
1/kkg RM  (56 to 9708 gal./lOOO Ib RM);  a BOD5  waste load range of
0.10 to 5.83 kg BOD5/kkg RM  (0.10 to  5.83 Ib  BOD5/1000  Ib  RM) ;
and  a production range of 3.6 to 390 kkg RM/day  (8000 to 860,000
Ib RM/day) .

Variations in waste water flow  per   unit  of   raw  material  are
largely   attributable   to  the  type   of   condensers  used  for
condensing the cooking vapors and, to a  lesser  extent,  on  the
initial  moisture  content of the raw material (see Section III) .
Table 7 shows that the average waste  water  flow for plants  using
barometric leg condensers is much higher, by at least a factor of
2,  than for those using either shell-and-tube or air condensers.
The range and standard deviation in the flow  values  are  large,
however,  for all three types of condensers, which undoubtedly is
partially caused by the type of  raw  materials  processed.   The
volume  of water used for cleanup can be a  significant portion of
the flow per unit of RM; typically it amounts  to  30  percent  of
the total flow.

A  regression  analysis  of the field sampling data revealed that
the raw BOD5 waste load correlates very well with grease and  COD
waste  loads.   Raw  BOD5  waste  load  also correlates with total
volatile solids  (TVS), total dissolved  solids   (TDS),  and  total


                              44

-------
Table 6.  Summary of Raw Waste Characteristics for Rendering Industry
Parameter*
Flow, 1/kkg RM
(gal. /1000 Ib RM)
Raw Material, kkg/day
(1000 Ib/day)
BOD , kg/kkg RM
SS, kg/kkg RM
Grease, kg/kkg RM
COD, kg/kkg RM
Total Volatile
Solids, kg/kkg RM
Total Dissolved
Solids, kg/kkg RM
Total Kjeldahl
Nitrogen, kg/kkg RM
Ammonia, kg/kkg RM
Nitrate, kg/kkg RM
Nitrite, kg/kkg RM
Chloride, kg/kkg RM
Total Phosphorus,
kg/kkg RM
Number of
Observations
47
48
29
26
18
16
18
17
17
16
14
13
14

17
Average
Value
3261
(403)
94
(206)
2.15
1.13
0.72
8.04
3.34
3.47
0.476
0.299
0.008
0.003
0.793

0.044
Standard
Deviation
—
94
(206)
1.34
1.39
1.14
8.32
3.09
3.05
0.313
0.196
0.016
0.011
0.767

0.064
High
20,000
(2400)
390
(860)
5.83
5.18
4.18
37.03
13.12
11.67
1.200
0.740
0.060
0.040
2.56

0.280
Low
467
(56)
3.6
(8)
0.10
0.03
0.00
1.59
0.04
0.01
0.120
0.080
0.0001
0.00002
0.080

0.003
  *kg/kkg RM =  lb/1000  Ib  RM
                                   45

-------
       Table 7.   Waste Water Flow and Raw Material Data Summary as Shown
Parameter
Flow,
1000 liters
(1000 gal.)




Raw Material ,
kkg/day
(1000 Ib/day)




Equipment
Type*
Total
Batch
Duke
C-G
Baro
S & T
Air
Total
Batch
Duke
C-G
Baro
S & T
Air
Number of
Observations
51
35
6
6
15
21
9
48
34
5
5
14
19
9
Average
Value
326(86)
314(83)
276(73)
110(29)
443(117)
185(49)
64(17)
94(206)
60(132)
195(430)
128(282)
37(82)
132(291)
62(137)
Standard
Deviation
643(170)
708(187)
166(44)
42(11)
764(202)
174(46)
38(10)
94(206)
80(176)
90(198)
61(135)
44(98)
89(195)
37(82)
High
Value
3028(800)
3028(800)
488(129)
170(45)
2952(780)
628(166)
121(32)
390(860)
390(860)
318(700)
204(450)
182(400)
318(700)
114(250
Low
Value
3.8(1)
3.8(1)
64(17)
68(18)
7.6(2)
7.6(2)
19(5)
3.6(8)
3.6(8)
68(150)
61(135)
5.4(12)
11(25)
11(25)
^Values listed as:
     o    Total summary  of  all  data, regardless  of  equipment  type.
     o    Batch, Duke, or C-G:   Summary  of  the information on plants  having
          these cookers, respectively.
     o    Baro,  S &  T, or Air:   Summary  of  the information on plants  having
          barometric leg, shell-and-tube, and air condensers, respectively.
                                     46

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Kjeldahl  nitrogen  (TKN).  This means that an increase  (decrease)
in one of these waste load parameters will account for a  certain
predictable  increase   (decrease) in one of the other parameters.
In fact, the square of the correlation  coefficient   (called  the
coefficient of determination) is a measure of the predictability.
Consequently,  the  high  degree  of correlation between BOD5 and
grease waste load implies that much  of  the  variation  in  BOD5
waste  load  is  caused  by  variations  in the grease load.  The
correlation coefficients from these  analyses  are  presented  in
Table 8.
              Table  8.  Correlation Coefficients of Several
                        Raw Waste Load Parameters with EOD5
                        from the Field Sampling Results
                       Parameter	

                       Grease

                       COD

                       Total Volatile
                       Solids

                       Total Dis-
                       solved  Solids

                       Kjeldahl
                       Nitrogen
 Correlation
.Coefficient

    0. 905

    0.933

    0. 789


    0.796


    0.580
The  basic  manufacturing  processes  in  independent rendering  (see
Section IV) should  have  no  influence   on  the  raw  waste  load,
because  they are universal.  However,  some processing equipment,
such as  cookers  and  condensers,   dc   differ  significantly  in
operating  principles.   However,  a comparison of data for batch
versus Duke and C-G continuous cookers  and for the three types of
condensers—barometric leg,  shell-and-tube, and air—revealed  no
discernible  difference  in  raw BOD5_ waste load.  These data were
presented in Section IV  and  Figures  8 and 9,  along with a further
discussion.   Incidentally,   it  was previously  mentioned   and
illustrated  with   the   data  from   Table  7  that barometric leg
condensers use far  more  water per unit  of raw material processed.
Obviously, the amount of  water  used   for  condensing  does  not
affect  the  raw waste load  per unit of RM processed.  In fact,  a
regression analysis for  raw  BOD5 waste  load and waste water   flow
oer   unit   of   RM  processed  revealed  no correlation.   The
correlation coefficient  for  this analysis  was  -0.027.   Earlier
studies  on  meat   packing  plants8  and poultry slaughterhouses 11
revealed a strong positive relationship between   raw  waste   load
and water use.
                              47

-------
The  effect  of plant size  (amount of raw  materials  processed per
day)  on waste load as measured by BOD5 was assessed  by a multiple
regression  analysis.   This  analysis   showed    no    discernable
relationship  between  BOD5  per  unit   of RM processed and plant
size.  The correlation coefficient was 0.062 and  the  square of
this  coefficient,  which is the coefficient of determination, is
only 0.0038.

Plant size does, however, appear to be related   to  the  type of
cooker and condenser used.  Table 7 shows  that  the average amount
of  raw  material  processed  is  smaller   for  plants using batch
cookers and barometric  leg  condensers  than   for  plants  using
continuous   cookers    (Duke  and  C-G)  and  shell-and-tube  air
condensers.   Plants  with  batch  cookers and  barometric   leg
condensers frequently are older plants—built more than ten years
ago.   Plant  age,  although  apparently related to  both size and
equipment type, is not related to waste  load.   Size  and age  were
factors   considered    in  categorizing  the  industry  and  were
discussed in more detail in Section IV.

                     Sources of Waste Water

The most typical process and waste water flow arrangement used by
the  independent rendering  industry  is  shown   schematically in
Figure  11.  Hide curing is shown in this  figure (even though the
majority of the plants  do  not  handle  hides)   because  it  can
represent a significant portion of the total raw waste load.

Some  plants,  rather  than  using  the  sequence of  manufacturing
processing illustrated  in Figure 11, use slight variations of it.
A  plant processing poultry by-products,  for example, will usually
have two complete processing operations  on the  same  premises.
One  operation is for poultry offal and  dead birds,  which will be
very similar to the arrangement shown in  Figure  11;  the  other
operation  will  be  for the feathers and  blood.  The feather and
blood operation will  not  include  the  liquid-solid  separation
process  nor any of the grease processes.   Other rendering plants
may not have blending and bagging processes if, for example, they
do not handle blood or  feather meal and  their meat  and  bone is
consistently of a high  crude protein level. Still others may not
have  a  size-reduction process; these include  plants that handle
grease only, or a high  percent of  poultry offal.   Plants  that
have  large grease operations probably vary more from the process
flow arrangement of Figure  11 than do any  other plants.  In these
operations, there is receiving, cooking  (or heating),  separation
of the  water  and solids from the grease, storage and shipping.
Yet these operations still have  the  same characteristic  waste
loads as the other rendering plants.  In addition, there are very
few  plants  with  large  grease  operations,   and  most of these
usually have a separate operation schematically similar  to  that
of Figure 11 for processing of fats and  other  raw materials.

Figure  11  also  shows  the  major  sources   of  waste  water as
indicated by the dashed  line.   The  sources   include  auxiliary
operations in addition  to manufacturing  processes.  The auxiliary


                             48

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            MANUFACTURING PROCESSES
                                                          WASTE WATER FLOW
            RAW MATERIAL
              RECEIVING
                SIZE
             REDUCTION
             COOKING AND
               DRYING
  VAPOR
CONDENSING
            LIQUID - SOLID
             SEPARATION
                    r
     ODOR
   CONTROL
 MEAL MILLING
AND SCREENING
   BLENDING
 AND BAGGING
                    r
                                         SPILLS
                    I	
PLANT AND TRUCK
   CLEAN UP
                                               	1
                                    GREASE AND SOLIDS
                                       RECYCLED TO
                                    COOKING & DRYING
                                                  MATERIALS
                                                  RECOVERY
                                                      r:
                                                  RAW WASTE
                                        SANITARY
                                        FACILITIES
                                                             ,FRESH WATER

                                                          -*- PRODUCT AND MATERIAL FLOW

                                                          •*- WASTE WATER FLOW
     Figure 11.   Typical Rendering  Process  and Waste Water  Flow Arrangement
                                          49

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operations are odor control, spills, and plant and truck  cleanup;
the  manufacturing processes are receiving, vapor condensing  from
cooking and drying, and hide curing.  These sources this  section.
Total plant  waste  loads  including  the  effects  of  materials
recovery  were  presented  in Table 6 and discussed previously in
this section.


                     Raw Materials Receiving

Liquid drainage from raw materials receiving areas can  contribute
significantly to the total raw waste load.  Frequently  throughout
the processing period large amounts of raw  materials   accumulate
in  receiving areas  (either in bins or on floors) allowing  strong
liquors to drain off and enter sewers.  This is  especially  true
of  plants  processing  poultry feathers because of the manner in
which feathers, offal and blood are sometimes  handled  at  their
source   (poultry   slaughterhouses).  As a result, the feathers or
combined feathers  and offal often contain much blood  and  excess
water.   At  one   such  plant  that  was  sampled,  this  drainage
amounted to roughly 20  percent  of  the  original  raw  material
weight  and  had an average BOD5 value of 12,500 mg/1.  This  BOD5
loss amounted to 2.5 kg BOD5/kkg RM  (2.5 lb/1000 Ib  RM)  and 43
percent of the total plant raw BOD5 waste load.  In another plant
that  had a dual operation for poultry offal and for feathers and
blood, the loss caused by drainage from the feather operation was
calculated from field sampling information; it was about  1.4 kg
BOD5/kkg  RM,  or  about  39  percent  of the waste load  prior to
materials recovery processes.  In these examples, the waste  load
caused  by  drainage  of  liquors from raw materials is obviously
very significant.  A partial remedy for these losses,   which  was
practiced in a plant included in the field survey, is to  isolate,
steam sparge, and  screen these waste waters.
                        Vapor Condensing

Condensate   from   the  cooking  and  drying   process  typically
contributes atout  30 percent of the total  raw   BOD5   waste  load.
The  field  sampling  condensables  was  from   0.049   to  1.53  kg
BOD5/kkg RM (0.049 to 1.53 Ib BOD5/1000 Ib RM),  with   an  average
value  of  0.73 kg/kkg RM.  A summary of concentrations and waste
loads of undiluted  condensed  cooking  vapors  is presented  in
Tables  9 and 10,  respectively.  of course,  being undiluted means
the vapors were condensed in a closed system:   air or  shell-and-
tube  condensers.   A number of factors, such  as rate of cooking,
speed
of agitation, cooker overloading, foaming, lack of traps,  etc.,
are  probably  responsible  for  much of the variation in values.
Raw materials could also have a  direct  effect  on   the  values,
although  no  discernible  difference  between  raw materials and
total plant raw waste load was revealed by a multiple  regression
analysis, as discussed in Section IV.
                               50

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Table 9.  Concentrations of Undiluted Condensed Cooking Vapors
Parameter
BOD5
COD
Total
Volatile
Solids
Total
Dissolved
Solids
Total
Phosphorus
Chlorides
Total
Kjeldahl
Nitrogen
Nitrate
Nitrite
Grease
Suspended
Solids
mg/1
Number of
Observations
11
10


10


7

7
7


7
7
7
7

10
Average
Value
1723
2207


185


201

6.3
196


493
263
0.11
109

60.9
Standard
Deviation
1165
1383


169


143

6.3
212


317
238
0.08
76

94.3
Low
Value
80
192


15


59

2.45
13


36
14
0.01
63

11
High
Value
3950
4212


579


413

20.4
593


1005
750
0.02
271

327
                               51

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The  pH of the condensables averaged  8.7 for 11 observations with
a standard deviation of 1.12 and with low and high  values  of   6.8
and  9.7, respectively.  Incidentally, the number of  observations
for the waste parameters in these tables is frequently   less   for
the waste load values than for the concentration values.   This is
because  some  of the data were lacking to permit the calculation
of the waste load; e.g., the amount of raw material processed was
not always known.

The use of barometric leg condensers  will dilute the  condensables
and thus lower the concentrations from those listed in   Table  9.
In many
cases,  treated waste waters are recycled through barometric legs
for  condensing  cooking  vapors  and  to  allow  a  high   water
throughput to lower the barometric leg effluent temperature to at
least  38°C  (10C°F) for odor control.  This practice  may increase
the actual waste load slightly; however, an analysis  of  the  data
by type of condenser  (see Section IV) did not reveal  any distinct
differences  in waste loads caused by  type of condenser.


               Spills and Plant and Truck Cleanup

Washdown    (cleanup)   of  the  plant,  trucks,  and  spills  can
contribute significantly to the total plant raw waste  load.   In
one  plant   that  was sampled, the waste waters from  cleanup were
isolated from the condensables.  Analysis of this source revealed
that cleanup in this plant added 16.2 kg BOD5/kkg   (Ib   BOD5/1000
Ib) RM to the raw waste load, an extraordinarily high value.   The
reasons  for this high value were that the plant used  a constant
flow of hot  water throughout the  entire  production  period;  it
constantly   cleaned  up  spills from  worn, leaking  equipment,  and
frequently shut  off  the  automatic  skimmer  of   the   materials
recovery  systems,  resulting  in  large amounts of grease carry-
over.  The large amounts of hot water helped maintain the  cleanup
effluent  temperature  above  52°C    (125°F),   thus    preventing
efficient  grease  separation.   Needless  to  say, the  plant  was
clean.  In another plant, the BOD5 and suspended solids  load just
from cleanup were 43 and 50 percent of the total, respectively.

It was observed on the field survey studies that spills  caused by
equipment breakdown occurred frequently and that leaks  from  worn
equipment  were  not  uncommon.   This  does not mean that spills
cannot be prevented or limited; however, the common practice when
equipment breaks down is to open it and dump  materials   directly
on  the  floor.   This allows free draining grease  and  liquors to
enter the sewers.  Also, after the bulk of the solids  have  been
shoveled  up,  the remainder is washed off.  More effort could be
made to contain materials  when  equipment  breaks  down  and  to
better   maintain   equipment   by  use  of  regularly   scheduled
maintenance  programs on equipment during down-time.
                                52

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Table 10.  Waste Loads for Undiluted Condensed Cooking Vapors
Parameter
BOD
COD
Total
Volatile
Solids
Total
Dissolved
Solids
Total
Phosphorus
Chloride
Total
Kjeldahl
Nitrogen
Nitrate
Nitrite
Grease
Suspended
Solids
kg/kkg KM or lb/1000 Ib BM
Number of
Observations
10
7


7


6

6
6


6
6
6
7

9
Average
Value
0.73
1.10


0.086


0.21

0.0021
0.056


0.17
0.081
0.0018
0.14

0.018
Standard
Deviation
0.50
0.75


0.093


0.25

0.00015
0.078


0.12
0.067
0.0038
0.25

0.017
High
Value
1.53
2.23


0.31


0.73

0.0043
0.21


0.35
0.16
0.0096
0.70

0.056
Low
Value
0.049
0.12


0.0032


0.0013

0.00081
0.0046


0.022
0.0086
0.000008
0.015

0.0058
                              53

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                          Odor Control
Air scrubbers are common  in  the  rendering  industry   for   odor
control.   The  relative  volume  of  water used,  however, varies
greatly,  although  the  waste  load  caused  by    scrubbing    is
insignificant.   The  reason  for  the variation in water  flow  is
that scrubbers for plant  air  and  other  low-aerosol-containing
emissions   (smoke and grease particulates) can tolerate  recycling
of up to 95  percent  of  the  scrubbing  waters.   However,  air
heavily  laden  with  odorous  aerosols  is usually scrubbed  with
fresh water  to  prevent  grease  buildup  and  clogging  of  the
equipment.   For example, one dual operation  (one  batch  operation
and one continuous operation) plant contained  a   total  of   nine
scrubbers.   Although  some  scrubbers did use partial recycle  of
scrubbing water, the volume of  scrubbing  waters   was   about  75
percent  of  the  total plant effluent volume.  Typically, plants
will have only two or three scrubbers:  one for total plant   air,
one  for  the  presses,  and  possibly one for the ring  or rotary
dryers.  Most of the scrubbing waters then are recycled, and  the
relative  waste  water  volume  from  scrubbing  is small.   For
example, one plant that was sampled had  two  scrubbers—one  for
plant air and one for a dryer—and the volume of waste water  from
the  scrubbers amounted to only six percent of the total effluent
volume.
                           Hide Curing

Hide curing is conducted in a  number  of  independent   rendering
plants.   The waste water from this operation is high in strength
but relatively  low  in  volume,  particularly  when  the  curing
solution  is  only  dumped  a  few  times  each  year.   Data  from
previous studies°2,8 indicate that about 7.7 liters  (2  gallons)
is  the  waste water overflow volume for brine curing each cattle
hide.

The waste load for just curing hides at an independent   rendering
plant   is,  however,  considerably  less  than the waste load for
curing  at a packing plant.  This is because curing of hides at   a
packing  plant includes a number of additional operations.  These
are washing, demanuring, and defleshing.  In addition,   the   time
differential   between  hide  removal  and  hide   delivery at   a
rendering plant allows for much of the blood and other fluids  to
seep  from  the hides.  This time differential ranges from  several
hours to a  few days.  Also, hides and accompanying flesh  removed
from  dead  animals at a rendering plant do not appear to  contain
anywhere near the amount of blood and fluid that a hide  removed
at  a   packing  plant  from an animal killed  just  moments  earlier
contains.

Data from the recent study of packing  plants8  states   that  the
average   waste   load   for  handling  and  curing hides of   a
packinghouse is 1.5 kg BOD5/kkg LWK  (live weight killed).   Since
the  average LWK for beef is about 454 kg  (1000 pounds), this can
be equivalently expressed as 0.68 kg  BOD5/hide.    On  the other
hand,   a  study  of  tannery effluents0* lists the waste load for
just hide curing at a tannery  as  3.9  kg  BOD5/kkg  hides   (3.9
lb/1000  Ib).  Using an average hide weight of 32  kg  (70 pounds),


                              54

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   Table 11.   Waste Load Characteristics for Hide Curing at an
              Off-Site Rendering Plant Versus Those for a Tannery
12
Table 12.  Measured Waste Strengths of Tank Water
           and Blood Water
en
en
Parameter
BOD
COD
Total Volatile
Solids
Suspended
Solids
Kjeldahl
Nitrogen
Ammonia
Nitrate
Nitrite
Total
Phosphorus
Total Dis-
solved Solids
Chloride
Grease
kg /hide
Rendering
Plant
0.11
0.21
0.17
0.064
0.014
0.0013
4.4 x 10~5
4.1 x 10~6
0.0021
2.9
1.26
0.0011
T annery
0.12
0.24

0.08





0.32
Parameter
BOD5
COD
Total Volatile
Solids
Total Dissolved
Solids
Total
Phosphorus
Chloride
Total Kjeldahl
Nitrogen
Ammonia
Nitrate
Nitrite
Grease
Suspended
Solids
mg/1
Tank Water
31,390
49,152
36,739
54,791
1,350
8,638
2,187
81
3.43
0.35
9,901
6,647
Blood
Water
18,950
27,200
17,516
315
3,498
1,813







-------
this value can be expressed as 0.12 kg  (0.26 Ib) BOD5  per  hide.
This  latter  example  should also typify the waste load for hide
curing at an independent rendering plant.  In fact,  analysis  of
only  the hide curing effluent at one independent rendering plant
yielded a BOD5 waste load of 0.11 kg  (0.24  Ib)  per  hide.   The
results  of  this  analysis  are  summarized  in  Table  11.  For
comparison, the value recalculated from reference 12, assuming 32
kg/hide (70 pounds), is also included.


                      Miscellaneous Sources

Sewered tankwater and blood water  are  major  sources  of  waste
load.   The  sources of tank water are grease processing, and wet
and low-temperature rendering; the source of blood water is  from
processing  blood by steam sparging and then separating the blood
water from the coagulated blood by screening.   Fortunately,  not
many   independent  rendering  plants  have  the  processes  that
generate these sources of  waste.   Also,  some  plants  that  do
generate  tankwater eliminate it as a waste source by evaporating
it down to stick, which is  used  for  tankage  in  dry  inedible
rendering.   As  mentioned  in  Section  III, the BOD5 and grease
concentrations of tankwater can be as high as  30,000  to  45,000
mg/1 and 20,000 to 60,000 mg/1, respectively.


Table  12  shows the measured waste strengths of tankwater from a
grease operation and of  blood  water  from  steam  sparging  and
screening  of  blood.  The waste load resulting from the sewering
of the tankwater was 9.4 kg BOD5/kkg  (9.4 Ib BOD5/1000 Ib)  grease
before primary treatment (materials recovery process).   However,
much  of  this waste load was removed by primary treatment, since
the amount of grease processed was about 63 percent of the  total
plant  RM  and  since  the total plant waste load was only 2.2 kg
BOD5/kkg (2.2 lb/1000 Ib)  RM.  Likewise, the  sewering  of  blood
water  added  16.3  kg  BOD5/kkg  blood before primary treatment.
Judging from the values of the total plant raw waste load and the
waste loads of the  other  sources,  it  would  appear  that  the
primary  treatment  recovered  very  little, if any, of the waste
load from the sewering of blood water; this is as  expected.   It
should  be pointed out, however, that the blood screening process
was not very efficient and that  a  pilot  study  at  that  plant
revealed  that  an improved screening process would significantly
lower the load from sewering blood water.
                                56

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                           SECTION VI

                SELECTION OF POLLUTANT PARAMETERS


                       SELECTED PARAMETERS

Based on a review of the Corps of Engineers1 Permit  Applications
from the independent renderers, previous studies on similar waste
waters  such  as  from  the  meat  packing plants, industry data,
questionnaire data, and data obtained from sampling  plant  waste
waters  during  this study, the following chemical, physical, and
biological constituents constitute pollutants as defined  in  the
Act.

          BOD5  (5-day, 20°C biochemical oxygen demand)
          COD  (chemical oxygen demand)
          Total suspended solids  (TSS)
          Total dissolved solids  (TDS)
          Total volatile solids  (TVS)
          Oil and grease
          Ammonia nitrogen
          Kjeldahl nitrogen
          Nitrates and nitrites
          Phosphorus
          Chloride
          Bacteriological counts  (total and fecal coliform)
          pH, acidity, alkalinity
          Temperature

On  the  basis  of  all evidence reviewed, there do not exist any
purely hazardous pollutants  (such as heavy metals or  pesticides)
in  the  waste  discharge  from the independent rendering plants.
While all of the above parameters are in present  renderer  plant
waste  water, the amount and reliability of available data, costs
for treatment or control, and  availability  of  technology  were
factors  which  resulted  in  limitations  only  for  the primary
parameters BOD5, TSS, Oil and grease, fecal  coliforms,  ammonia,
phosphorus and pH.


        RATIONALE FOR SELECTION OF IDENTIFIED PARAMETERS

             5-Day Biochemical Oxygen Demand  (BOD5)

This  parameter is an important measure of the oxygen consumed by
microorganisms in the aerobic decomposition of the wastes at 20°C
over a five-day period.  More simply, it is an  indirect  measure
of  the  biodegradability of the organic pollutants in the waste.
BOD5 can be related to the depletion of oxygen in  the  receiving
stream or to the requirements for the waste treatment.  Values of
BOD5  range  from  100  to  9000  mg/1 in the raw waste, although
typical values range from 1000 to 5000 mg/1.  Low BOD5 values  in
the raw waste are frequently the result of the dilutional effects
of using a barometric condenser; high values due to a combination


                               57

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of  factors, such as undiluted condenser waters, frequent  spills,
and a relatively  large  amount  of  drainage  of  high  strength
liquids from the raw material.

If  the  BOD5  of  the final effluent of a rendering  plant into a
receiving body is too high, it will reduce the  dissolved   oxygen
level in that stream to below a level that will sustain most fish
life;  i.e.,  below about 4 mg/1.  Many states currently restrict
the BOD5 effluents to below 20 mg/1 if the  stream  is  small  in
comparison with the flow of the effluent.  A limitation of 200 to
300  mg/1  of  BOD5 is often applied for discharge to a municipal
sewer, and surcharge rates often apply if the BOD5 is above  the
designated  limit.   BOD5 is included in the effluent limitations
recommended because its discharge  to  a  stream  is  harmful  to
aquatic life since it depletes the oxygen supply.

A  20-day  biochemical  oxygen  demand   (BOD20), sometimes called
"ultimate" BOD, is usually a better measure  of  the  waste load
than  BOD5.  However, the test for BOD20 requires 20  days  to run,
so it is an impractical measure for most purposes.

Biochemical oxygen demand   (BOD)  is  a  measure  of  the   oxygen
consuming  capabilities  of  organic matter.  The BOD does not in
itself cause direct harm to a water system, but it does exert  an
indirect  effect  by  depressing the oxygen content of the water.
Sewage and other organic  effluents  during  their  processes  of
decomposition  exert  a BOD, which can have a catastrophic effect
on the ecosystem by depleting the oxygen supply.  Conditions  are
reached  frequently  where  all  of  the  oxygen  is  used  and the
continuing decay process causes the production of  noxious gases
such  as  hydrogen  sulfide  and  methane.  Water with a high BOD
indicates  the  presence  of  decomposing  organic    matter  and
subsequent  high  bacterial  counts  that degrade its quality and
potential uses.

Dissolved oxygen  (DO) is a water  quality  constituent  that,  in
appropriate   concentrations,  is  essential  not  only  to keep
organisms living but also to sustain species reproduction, vigor,
and the development of populations.  Organisms undergo stress  at
reduced  DO  concentrations  that  make them less competitive and
able to sustain their species  within  the  aquatic   environment.
For  example,  reduced  DO  concentrations  have  been  shown  to
interfere with fish population through delayed hatching of eggs,
reduced  size  and vigor of embryos, production of deformities in
young, interference with food digestion,  acceleration  of blood
clotting,  decreased tolerance to certain toxicants,  reduced food
efficiency  and  growth  rate,  and  reduced  maximum  sustained
swimming  speed.   Fish  food  organisms  are  likewise  affected
adversely in conditions with suppressed DO.    Since   all   aerobic
aquatic   organisms   need   a  certain  amount  of   oxygen,  the
consequences of total lack of dissolved oxygen due to a high  BOD
can kill all inhabitants of the affected area.

If  a  high  BOD  is present, the quality of the water is  usually
visually degraded by the presence of  decomposing  materials  and
                              58

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algae  blooms  due  to the uptake of degraded materials that form
the foodstuffs of'the algal populations.
                               59

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                  Chemical Oxygen Demand  (COD)

COD is yet. another measure of oxygen  demand.    It   measures  the
amount  of  organic   (and  some  inorganic)   pollutants   under  a
carefully controlled direct chemical oxidation  by   a  dichromate-
sulfuric  acid  reagent.   COD  is  a  much more rapid measure of
oxygen  demand  than  BOD5,  and  is  potentially   very    useful.
However,  it  does  not  have  the  same  significance, and at the
present time cannot be substituted  for   BOD5,   because   COD:BOD5
ratios vary with the types of wastes.  The COD  measures  more than
only those materials that will readily biodegrade in a stream and
hence deplete the stream's dissolved oxygen supply.

COD  provides  a  rapid determination of  the  waste  strength.  Its
measurement  will  indicate  a   serious   plant   or   treatment
malfunction  long  before  the BOD5 can be run.  A  given plant or
waste treatment system usually has a relatively narrow  range  of
COD:BOD5   ratios,   if  the  waste  characteristics  are  fairly
constant, so experience permits a judgment to be made concerning
plant  operation from COD values.  In the rendering industry, COD
ranges from about 1.5 to 6 times the BOD5 in  both   the   raw  and
treated   wastes,  with  typical  ratios  between   1.5  and 3.0.
Although the nature of the impact of COD  on receiving waters  is
the  same  as  for  BOD5,  BOD_5  was  chosen  for inclusion in the
effluent limitations rather than COD because  of the industry's
frequent use and familiarity with BOD5.

                  Total Suspended Solids  (TSS)

This  parameter  measures  the  suspended material  that  can be
removed from the waste waters by laboratory filtration,  but does
not  include  coarse  or  floating matter that  can  be screened or
settled out readily.  Suspended solids are a  visual  and  easily
determined  measure  of  pollution  and   also  a measure  of the
material that may settle in tranquil or   slowmoving  streams.   A
high  level  of  suspended  solids is an  indication of high BOD5.
Generally, suspended solids range from one-third to three-fourths
of the BOD5 values in the raw waste.  Suspended solids are also a
measure of the effectiveness of solids removal   systems   such  as
clarifiers and fine screens.

Suspended  solids  frequently  become  a  limiting factor in waste
treatment when the BOD5 is less than about 20 mg/1.   In  fact,  in
highly  treated  waste,  suspended  solids  usually have a higher
value than the BOD5, and in this case, it may be easier  to  lower
the  BOD5 even further, perhaps to 5 to 10 mg/1, by filtering out
the suspended solids.  Suspended  solids  in  the   treated waste
waters  of  rendering  plants  correlate  well with  BOD5, COD, and
total volatile solids.  The same is not true,  however,   for  the
raw wastes.

Suspended  solids  in  receiving waters act as  adsorption surface
for ionic nutrients, and as a substrate for bacterial population,
thus resulting  in  high  BOD5  values.    Suspended  solids  also


                             60

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inhibit   light   penetration  and  thereby  reduce  the  primary
productivity of algae  (photosynthesis).  Because  of  the  strong
impact  suspended  solids can have on receiving waters, suspended
solids were included in the effluent limitations  recommended  in
this report.


Suspended  solids  include  both organic and inorganic materials.
The inorganic components  include  sand,  silt,  and  clay.   The
organic  fraction  includes  such  materials as grease, oil, tar,
animal and vegetable fats, various  fibers,  sawdust,  hair,  and
various  materials  from  sewers.   These  solids  may settle out
rapidly and bottom deposits are often a mixture of  both  organic
and   inorganic  solids.   They  adversely  affect  fisheries  by
covering the bottom of the stream  or  lake  with  a  blanket  of
material that destroys the fish-food bottom fauna or the spawning
ground  of  fish.   Deposits  containing  organic  materials  may
deplete bottom oxygen  supplies  and  produce  hydrogen  sulfide,
carbon dioxide, methane, and other noxious gases.

In  raw  water  sources  for  domestic  use,  state  and regional
agencies generally specify that suspended solids in streams shall
not be present in sufficient concentration to be objectionable or
to interfere with normal treatment processes.   Suspended  solids
in  water may interfere with many industrial processes, and cause
foaming in boilers, or  encrustations  on  equipment  exposed  to
water, especially as the temperature rises.  Suspended solids are
undesirable  in  water  for  textile  industries; paper and pulp;
beverages;  dairy  products;  laundries;   dyeing;   photography;
cooling  systems,  and  power  plants.   Suspended particles also
serve  as  a  transport  mechanism  for  pesticides   and   other
substances which are readily sorbed into or onto clay particles.

Solids  may  be suspended in water for a time, and then settle to
the  bed  of  the  stream  or  lake.   These  settleable   solids
discharged  with  man's wastes may be inert, slowly biodegradable
materials,  or  rapidly  decomposable   substances.    While   in
suspension,  they  increase  the  turbidity  of the water, reduce
light penetration  and  impair  the  photosynthetic  activity  of
aquatic plants.

Solids  in  suspension  are aesthetically displeasing.  When they
settle to form sludge  deposits on the stream or  lake  bed,  they
are  often  much  more  damaging  to  the life in water, and they
retain the  capacity   to  displease  the  senses.   Solids,  when
transformed  to  sludge  deposits,  may  do a variety of damaging
things, including blanketing the stream or lake bed  and  thereby
destroying  the  living  spaces  for those benthic organisms that
would otherwise occupy the  habitat.   When  of  an  organic  and
therefore decomposable nature, solids use a portion or all of the
dissolved  oxygen  available in the area.  Organic materials also
serve as a seemingly inexhaustible food  source  for  sludgeworms
and associated organisms.
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Turbidity  is  principally  a  measure  of  the   light  absorbing
properties of suspended solids.   It  is  frequently  used  as  a
substitute  method  of  quickly  estimating   the   total suspended
solids when the concentration is relatively low.


                  Total Dissolved Solids  (TDS)

The  total  dissolved  solids  in  the  waste waters   of   most
independent  rendering  plants contain both organic and inorganic
matter.  A large source of organic  dissolved solids  is  blood.
Inorganic  salts  can  be a major part of the dissolved solids if
hide curing is conducted at the plant.  The amount  of  dissolved
solids will also vary to a large extent with  the  type of in-plant
operations  and the housekeeping practices.   Dissolved solids are
of the same order of magnitude and correlate  well with the  total
volatile  solids  in  both  the  raw  and  treated  waste waters,
implying that, in general,  most  of  the  dissolved  solids are
volatile.    The  inorganic  dissolved  solids are  particularly
important because they are relatively  unaffected  by  biological
treatment  processess.   Therefore,  unless   removed,  they  will
accumulate within the water system on total recycle or reuse, or
build  up  to  high  levels  with partial recycle or reuse of the
waste water.

Dissolved solids affect the ionic nature of receiving waters and
are  usually  the  nutrients  for bacteria and protozoans.   Thus,
they increase the eutrophication rate of the   receiving  body of
water.   Total dissolved solids were not included in the effluent
limitations  recommended  in  this  report  because  the  organic
portion  would  be  limited  by BOD5 limitations  and the nutrient
portion by the nitrogen and phosphorus limitations.

In  natural  waters  the  dissolved  solids   consist  mainly  of
carbonates,   chlorides,   sulfates,   phosphates,  and  possibly
nitrates of  calcium,  magnesium,  sodium,  and   potassium,  with
traces of iron, manganese and other substances.

Many  communities in the United States and in other countries use
water supplies containing 2000 to 4000 mg/1 of dissolved  salts,
when   no  better  water  is  available.   Such   waters  are not
palatable, may not quench thirst, and may have a  laxative  action
on  new  users.   Waters  containing more than 4000 mg/1 of total
salts are generally considered unfit for human use,  although in
hot  climates  such  higher  salt concentrations  can be tolerated
whereas they could not in temperate climates. Waters  containing
5000  mg/1  or  more are reported to be bitter and act as bladder
and intestinal irritants.  It is generally agreed that  the  salt
concentration  of  good,  palatable  water  should not exceed 500
mg/1.

Limiting concentrations of dissolved solids for fresh-water  fish
may  range  from  5,000  to 10,000 mg/1, according to species and
prior acclimatization.  Some fish are adapted to  living  in  more
saline  waters,  and a few species of fresh-water forms have been
found in natural waters with a salt concentration  of  15,000 to
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20,000  mg/1.   Fish  can  slowly  become  acclimatized to higher
salinities, but fish in waters of  low  salinity  cannot  survive
sudden  exposure to high salinities, such as those resulting from
discharges of oil-well brines.  Dissolved  solids  may  influence
the  toxicity  of  heavy metals and organic compounds to fish and
other aquatic life, primarily because of the antagonistic  effect
of hardness on metals.

Waters  with total dissolved solids over 500 mg/1 have decreasing
utility as irrigation water.  At 5,000 mg/1 water has  little  or
no value for irrigation.

Dissolved  solids  in  industrial  waters  can  cause  foaming in
boilers and cause interference with cleanness, color, or taste of
many finished products.  High contents of dissolved  solids  also
tend to accelerate corrosion.

Specific  conductance  is  a  measure of the capacity of water to
convey an electric current.  This  property  is  related  to  the
total  concentration  of  ionized  substances  in water and water
temperature.  This property is frequently used  as  a  substitute
method of quickly estimating the dissolved solids concentration.

                   Total Volatile Solids  (TVS)

Total volatile solids is a rough measure of the amount of organic
matter  in  the  waste  water.   Actually  it  is  the  amount of
combustible material  in both the total dissolved solids and total
suspended solids.  Total volatile solids in the raw waste  waters
of  rendering  plants  correlates quite well with total dissolved
solids and COD, and fairly well with BOD5, SS, and grease;  total
volatile  solids  in  the final waste waters correlates well with
total dissolved solids and BOD5, and fairly well with SS, grease,
and  COD,  in  the  final  waste  waters.    Because   of   these
correlations  and  because  total volatile solids is a relatively
easy parameter to determine, it could be used as a  rapid  method
to determine a serious plant or treatment system malfunction.

Volatile  solids in receiving waters are food for microorganisms,
and thus create increased eutrophicaticn.   Effluent  limitations
for  total  volatile solids were not established because TVS will
be limited by limitations on other pollutant parameters  such  as
BOD5 and suspended solids.


                         Oil and Grease

Grease,  also  called  oil  and  grease, or hexane solubles, is a
major pollutant in the raw waste stream of rendering plants.  The
source of grease is primarily from spillages of processed  tallow
and grease and cleanup of equipment, floors, barrels, and trucks.
Grease  forms  unsightly  films  on  the  water,  interferes with
aquatic life, clogs  sewers,  disturbs  biological  processes  in
sewage  treatment  plants, and can also become a fire hazard.  It
is also a food source for microorganisms which may be pathogenic.
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The loading of grease in the raw waste load varies  widely,   from
less  than  0.1  to  about  15  kg/kkg RM.  The average  raw  waste
loading of grease is about 0.7 kg/kkg RM, which corresponds  to an
average concentration of about 1660 mg/1.  Grease may  be  harmful
to  municipal  treatment  facilities  and  to  trickling filters.
Grease correlates well with BOD5 and COD in the raw  wastes,  but
not  in the treated wastes.  Because grease appears to constitute
a major portion of the waste load from rendering plants, effluent
limitations were established for it.

Oil and grease exhibit  an  oxygen  demand.   Oil  emulsions  may
adhere  to  the  gills of fish or coat and destroy algae or  other
plankton.  Deposition of oil in the bottom sediments can serve to
exhibit normal benthic growths,  thus  interrupting  the  aquatic
food chain.  Soluble and emulsified material ingested  by fish may
taint the flavor of the fish flesh.  Water soluble components may
exert  toxic  action  on  fish.   Floating oil may reduce the re-
aeration of the water surface and in conjunction with  emulsified
oil   may   interfere   with   photosynthesis.   Water  insoluble
components damage the plumage and  costs  of  water  animals  and
fowls.   Oil  and  grease in water can result in the formation of
objectionable  surface  slicks  preventing  the  full    aesthetic
enjoyment  of  the  water.   Oil spills can damage the surface of
boats and can destroy the aesthetic  characteristics   of  beaches
and shorelines.

                        Ammonia Nitrogen

Ammonia  nitrogen  in  the raw waste is just one of many forms of
nitrogen in a waste stream.  Anaerobic decomposition of   protein,
which  contains  organic  nitrogen,  leads  to  the  formation of
ammonia.  Thus,  anaerobic  lagoons  or  digesters  produce   high
levels  of  ammonia.   Also, septic  (anaerobic) conditions within
the plant in traps, basins, etc., may  lead  to  ammonia  in the
waste  water.   Another  source of ammonia can be liquid drainage
from raw materials containing manure, and also from proteinaceous
matter such as blood that has been "aged."

Ammonia  is  oxidized   by   bacteria   in   a   process  called
"nitrification"   to nitrites and nitrates.  This may  occur  in an
aerobic treatment process and in a stream.   Thus,  ammonia   will
deplete the oxygen supply in a stream; its oxidation products are
recognized nutrients for aquatic growth.  Also, free ammonia in  a
stream is known to be harmful to fish.

Typical  concentrations  in  the  raw  waste range from  25 to 300
mg/1; however,  after  treatment  in  an  anaerobic  system,  the
concentrations  of ammonia can reach 100 to 500 mg/1.  Ammonia is
limited in drinking water to 0.05 to 0.1 mg/l.°3  In some cases  a
stream standard is less than 2 mg/1.   Effluent  limitations for
new  sources  and  the  1983  limits were established  for ammonia
because of the strong impact it can have on receiving  waters.
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Ammonia is a common  product,  of  the  decomposition  of  organic
matter.   Dead  and  decaying animals and plants along with human
and animal body wastes account for much of the  ammonia  entering
the  aquatic  ecosystem.   Ammonia exists in its non-ionized form
only at higher pH levels and is the most  toxic  in  this  state.
The  lower  the  pH,  the  more ionized ammonia is formed and its
toxicity  decreases.   Ammonia,  in  the  presence  of  dissolved
oxygen,  is  converted  to  nitrate  (NO3) by nitrifying bacteria.
Nitrite  (NO2), which is an intermediate product  between  ammonia
and  nitrate,  sometimes occurs in quantity when depressed oxygen
conditions permit.  Ammonia can exist in several  other  chemical
combinations including ammonium chloride and other salts.

Nitrates  are considered to be among the poisonous ingredients of
mineralized waters, with potassium nitrate being  more  poisonous
than   sodium  nitrate.   Excess  nitrates cause irritation of the
mucous linings of the gastrointestinal tract and the bladder; the
symptoms are diarrhea and diuresis, and  drinking  one  liter  of
water  containing 500 mg/1 of nitrate can cause such symptoms.

Infant  methemoglobinemia,  a  disease  characterized  by certain
specific blood changes  and  cyanosis,  may  be  caused  by  high
nitrate  concentrations  in  the water used for preparing feeding
formulae.   While  it  is  still  impossible  to  state   precise
concentration  limits,  it has been widely recommended that water
containing more than 10 mg/1 of nitrate nitrogen  (NO3-N)  should
not    be   used  for  infants.   Nitrates  are  also  harmful  in
fermentation processes and can cause disagreeable tastes in beer.
In most natural water the pH range is  such  that  ammonium  ions
 (NH4+)   predominate.    In   alkaline   waters,   however,  high
concentrations of un-ionized ammonia  in  undissociated  ammonium
hydroxide increase the toxicity of ammonia solutions.  In streams
polluted  with  sewage,  up  to  one  half of the nitrogen in the
sewage may be in the form of free ammonia, and sewage  may  carry
up  to 35  mg/1  of total nitrogen.  It has been shown that at a
level  of 1.0 mg/1 un-ionized ammonia, the ability  of  hemoglobin
to  combine  with  oxygen  is  impaired  and  fish may suffocate.
Evidence indicates  that  ammonia  exerts  a  considerable  toxic
effect  on  all aquatic life within a range of less than 1.0 mg/1
to 25  mg/1, depending  on  the  pH  and  dissolved  oxygen  level
present.

Ammonia  can  add  to  the problem of eutrophication by supplying
nitrogen through its breakdown products.  Some  lakes  in  warmer
climates, and others that are aging quickly are sometimes limited
by  the nitrogen available.  Any increase will speed up the plant
growth and decay process.

                        Kjeldahl Nitrogen

This   parameter  measures  the  amount  of  ammonia  and  organic
nitrogen; when used in conjunction with the ammonia nitrogen, the
organic  nitrogen  can  be  determined  by the difference.  Under
septic conditions, organic nitrogen decomposes to  form  ammonia.
Kjeldahl nitrogen is a good indicator of the crude protein in the


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effluent and, hence, of the value of proteinaceous material being
lost in the waste water.  The protein content is usually taken as
6.25  times  the  organic  nitrogen.   The  sources  of  Kjeldahl
nitrogen are basically the same as for ammonia  nitrogen,  above.
The  raw waste loading of Kjeldahl nitrogen is extremely variable
and is highly affected by blood losses from raw material drainage
and blood and feather operations, and by  liquid  entrainment  in
the cooking vapors.  Typical raw loadings range from 0.12 to 1.20
kg/kkg   (0.12  to  1.20  lb/1000 Ib) raw material; concentrations
range from about 60 to 800 mg/1, with the  lower  values  usually
caused  by  the  dilutional effects of barometric leg condensers.
Typical raw waste concentrations of Kjeldahl nitrogen are between
50 and 100  mg/1.   Kjeldahl  nitrogen  has  not  been  a  common
parameter  for regulation and is a much more useful parameter for
raw waste than for final effluent.  Even so, effluent limitations
for 1983 were  established  for  Kjeldahl  nitrogen  because,  in
addition  to  ammonia  which has a strong environmental impact on
receiving waters, it can be a major source of  organic  material,
which is food for microorganisms in receiving waters.


                      Nitrates and Nitrites

Nitrates  and nitrites, normally reported as N, are the result of
oxidation of ammonia and of  organic  nitrogen.   Nitrates  as  N
should  not  exceed  20  mg/1  in  water  supplies.04   They  are
essential nutrients for algae and other aquatic plant life.   For
these  reasons,  effluent limitations for new sources and for the
1983  limits  were  established  for  nitrites-nitrates   as   N.
Nitrites ranged from a trace to 0.040 kg/kkg RM in the raw wastes
and  from  a  trace  to  0.08  kg/kkg  EM  in the treated wastes;
nitrates ranged from a trace to 0.06 kg/kkg RM  in  the  raw  and
from a trace to 0.012 kg/kkg RM in the treated wastes.

Concentrations of nitrites varied from 0.02 to 26 mg/1 in the raw
and  from  O.OU  to 1.2 mg/1 in the final; nitrate concentrations
varied from 0.02 to 13 mg/1 in the raw and from 0.02 to 3.25 mg/1
in the treated waste.  Again, low values are primarily caused  by
the dilutional effects of barometric leg condensers.

Nitrates  and  nitrites  are  important  measurements, along with
Kjeldahl nitrogen, in that they allow for the  calculation  of  a
nitrogen  balance  on  the  treatment system.  In fact, the field
sampling data verified that when there was a substantial nitrogen
reduction by the treatment system, it  was  accompanied  by  good
BOD5, SS, and grease reductions.


                           Phosphorus

Phosphorus,  commonly  reported  as  P, is a nutrient for aquatic
plant life and can therefore cause  an  increased  eutrophication
rate in water courses.  The threshold concentration of phosphorus
in receiving bodies that can lead to eutrophication is about 0.01
ma/1.   The  primary  sources  of   phosphorus  in  raw waste from


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rendering are bone meal, detergents, and boiler water  additives.
The  total phosphorus in the raw effluent ranges from about 0.007
to 0.28 kg/kkg RM  (0.007 to 0.28 lb/1000 Ib  RM),  or  a  typical
concentration  range  of 3 to 50 mg/1 as P.  Effluent limitations
were  established  for  phosphorus  for  new  source  performance
standards  and  for  the  1983  limits  because  of its effect on
eutrophication rates.

During the past 30 years, a formidable case has developed for the
belief that increasing standing crops of aquatic  plant  growths,
which  often  interfere with water uses and are nuisances to man,
frequently are caused by increasing supplies of phosphorus.  Such
phenomena  are  associated  with  a  condition   of   accelerated
eutrophication  or  aging  of waters.  It is generally recognized
that phosphorus is not the  sole  cause  of  eutrophication,  but
there  is  evidence to substantiate that it is frequently the key
element in all of the elements required by fresh water plants and
is generally present  in  the  least  amount  relative  to  need.
Therefore, an increase in phosphorus allows use of other, already
present,  nutrients  for  plant  growths.   Phosphorus is usually
described, for these reasons, as a "limiting factor."

When a plant population is stimulated in production and attains a
nuisance status, a large number  of  associated  liabilities  are
immediately  apparent.   Dense  populations  of  pond  weeds make
swimming dangerous.   Boating  and  water  skiing  and  sometimes
fishing  may be eliminated because of the mass of vegetation that
serves as  a  physical  impediment  to  such  activities.   Plant
populations  have  been  associated with stunted fish populations
and with poor  fishing.   Plant  nuisances  emit  vile  stenches,
impart  tastes and odors to water supplies, reduce the efficiency
of industrial and municipal  water  treatment,  impair  aesthetic
beauty,   reduce  or  restrict  resort  trade,  lower  waterfront
property values, cause skin rashes to man during  water  contact,
and serve as a desired substrate and breeding ground for flies.

Phosphorus  in  the  elemental  form  is  particularly toxic, and
subject to bioaccumulation in  much  the  same  way  as  mercury.
Colloidal  elemental  phosphorus will poison marine fish (causing
skin tissue breakdown and discoloration).   Also,  phosphorus  is
capable  of  being concentrated and will accumulate in organs and
soft tissues.  Experiments  have  shown  that  marine  fish  will
concentrate phosphorus from water containing as little as 1 ug/1.


                            Chlorides
Chlorides  in  concentrations  of  the  order of 5000 mg/1 can be
harmful  to  people  and  other  animal  life.    High   chloride
concentrations   in   waters   can  be  troublesome  for  certain
industrial uses and for reuse or recycling of water.   The  major
sources  of  chlorides  from  rendering  plants are the salt from
animal  tissues,  hide  curing  operations,   and   blood.    The
concentrations  in raw waste are extremely variable from plant to
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plant, and are normally much higher for plants treating  hides  or
sewering blood waters  (e.g., drainage from poultry  feathers) than
they  are  for other plants.  The amount in the waste water  is an
indicator that these processes are being operated.  For   example,
chloride  concentrations from liquid drainage of  cured hides were
measured at 80,000 mg/1 as Cl; from  drainage  of  bloody waters
from  poultry  offal,  at  691 mg/1 as Cl; and from sewered  blood
waters from a blood operation, at 3500 mg/1 as Cl.  The  range  of
chloride  loadings in raw waste effluents is from 0.08 to greater
than 2.56 kg/kkg RM  (2.56 lb/1000 Ib RM).  Chloride loadings are
unaffected  by  biological treatment systems used by the industry
today, and once in the waste  waters  they  are   very  costly  to
remove.    While   high  chloride  concentrations  in  biological
treatment systems and receiving waters can  upset  the   metabolic
rate  of  organisms, effluent concentrations are  probably too low
to have a serious impact.

                         Fecal Coliforms

The coliform bacterial contamination  (total  and  fecal)   of raw
waste is substantially reduced  (by a factor of 100  to 200) in the
larger  waste  treatment  systems  used  in the industry, such as
anaerobic  lagoons   followed   by   several   aerobic    lagoons.
Chlorination will reduce coliform counts to less  than 400 per 100
ml  for  total,  and to less than 100 per 100 ml  for fecal.  Data
indicate that the total coliform of the raw waste from   rendering
plants  is  in  the  0.65- to 500-million per 100 ml range with a
median value of about 7 million per 100 ml; for   fecal   coliform,
the  range is 0.05- to 75-million per 100 ml, with  a median  value
of about 0.7 million per 100 ml.  Typically, states require  that
the  total  coliform  count  not exceed 50-200 MPN  (most probable
number) per 100 ml for waste  waters  discharged  into   receiving
waters.  Hence, most final effluents require chlorination to meet
state  standards.   When  waters  contain  200  counts   of  fecal
coliform  per   100   ml,   it   is   assumed   that   pathogenic
enterobacteriacea,  which  can  cause  intestinal infections, are
present.  Consequently, effluent limitations were established for
fecal coliforms.

Fecal  coliforms  are  used  as  an  indicator  since  they  have
originated  from  the  intestinal  tract of warm  blooded animals.
Their presence in  water  indicates  the  potential presence  of
pathogenic bacteria and viruses.

The  presence of coliforms, more specifically fecal coliforms, in
water is indicative of fecal pollution.  In general, the presence
of  fecal  coliform  organisms  indicates  recent  and    possibly
dangerous  fecal  contamination.   When  the fecal  coliform  count
exceeds 2,000 per  100  ml  there  is  a  high  correlation  with
increased numbers of both pathogenic viruses and  bacteria.

Many  microorganisms,  pathogenic  to  humans and animals, may be
carried in surface water, particularly that derived from effluent
sources which find their way into surface  water  from   municipal
and  industrial  wastes.   The  diseases associated with bacteria
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include   bacillary    and    amoebic    dysentery,    Salmonella
gastroenteritis,  typhoid  and paratyphoid fevers, leptospirosis,
cholera, vibriosis and infectious hepatitis.  Recent studies have
emphasized the value of fecal coliform density in  assessing  the
occurrence  of Salmonella, a common bacterial pathogen in surface
water.  Field studies involving irrigation water, field crops and
soils indicate that when the fecal  ccliform  density  in  stream
waters  exceeded  1,000  per 100 ml, the occurrence of Salmonella
was 53.5 percent.


                     pH, Acidity, Alkalinity

pH is of relatively minor importance,  although  waters  with  pH
outside  the  6.0  to  9.0  range can affect the survival of most
organisms, particularly invertebrates.   The  usual  pH  for  raw
waste  falls  between  6.0  and  9.0;  although  the  pH  of  the
condensables tends to be higher  (7.2 to 9.6).  This pH  range  is
close  enough to neutrality that it does not significantly affect
treatment  effectiveness  or  effluent  quality.   However,  some
adjustment  may  be  required,  particularly if pH adjustment has
been used to lower the pH for protein precipitation, or if the pH
has been raised for ammonia stripping.  The pH of the waste water
then should be returned to its  normal  range  before  discharge.
The  effect  of  chemical  additions  for pH adjustment should be
taken into consideration, as new pollutants could result.

Acidity and alkalinity are reciprocal terms.  Acidity is produced
by substances  that  yield  hydrogen  ions  upon  hydrolysis  and
alkalinity  is  produced  by substances that yield hydroxyl ions.
The terms "total acidity" and "total alkalinity" are  often  used
to  express  the  buffering  capacity  of a solution.  Acidity in
natural waters is caused by carbon dioxide, mineral acids, weakly
dissociated acids, and the salts of strong acids and weak  bases.
Alkalinity  is  caused  by  strong  bases and the salts of strong
alkalies and weak acids.

The term pH is a logarithmic expression of the  concentration  of
hydrogen  ions.   At  a  pH  of  7, the hydrogen and hydroxyl ion
concentrations are essentially equal and the  water  is  neutral.
Lower  pH  values  indicate  acidity while higher values indicate
alkalinity.   The  relationship  between  pH   and   acidity   or
alkalinity is not necessarily linear or direct.

Waters  with  a  pH  below  6.0  are  corrosive  to  water  works
structures, distribution lines, and household  plumbing  fixtures
and  can  thus  add  such constituents to drinking water as iron,
copper, zinc, cadmium and lead.  The hydrogen  ion  concentration
can  affect  the  "taste" of the water.  At a low pH water tastes
"sour." The bactericidal effect of chlorine is weakened as the pH
increases, and it is advantageous to keep  the  pH  close  to  7.
This is very significant for providing safe drinking water.

Extremes of pH or rapid pH changes can exert stress conditions or
kill  aquatic life outright.  Dead fish, associated algal blooms,


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and foul stenches are  aesthetic  liabilities  of  any  waterway.
Even moderate changes from "acceptable" criteria limits of pH are
deleterious  to  some  species.  The relative toxicity to aquatic
life of many materials is increased by changes in the  water  pH.
Metalocyanide  complexes can increase a thousandfold in toxicity
with a drop of 1.5 pH units.  The availability of  many  nutrient
substances  varies  with  the alkalinity and acidity.  Ammonia is
more lethal with a higher pH.

The lacrimal fluid of the human eye has a pH of approximately 7.0
and a deviation of 0.1 pH unit from the norm may  result  in  eye
irritation  for  the  swimmer.  Appreciable irritation will cause
severe pain.
                           Temperature

Because of  the  long  detention  time  at  ambient  temperatures
associated with typically large biological treatment systems used
for  treating  renderer plant waste water, the temperature of the
treated effluent from most rendering plants will be virtually the
same  as  the  temperature  of  the  receiving  body  of   water.
Therefore, temperature effluent limitations were not established.
Temperatures  of  the  raw waste waters are, however, between 29°
and 66°C  (85° and 150°F), with a  typical  value  of  about  52°C
 (125°F); temperatures, of course, run higher during summer months
than  winter months.  The major source of high temperature waters
is the condensed cooking vapors.  These high temperatures,  along
with  the  high  strength  wastes  are  an  asset  for biological
treatment  of  the  wastes,  maintaining  high  growth  rates  of
microorganisms  required  for  good  treatment.   However, if the
temperature of the raw wastes is too high—-greater than 52°C, the
raw  wastes  may  create  a  strong  odor  problem.   Raw   waste
temperatures below 38°C  (100°F) rarely cause odor problems.

Temperature  is  one  of the most important and influential water
quality characteristics.  Temperature  determines  those  species
that  may  be  present;  it  activates  the  hatching  of  young,
regulates their activity,  and  stimulates  or  suppresses  their
growth  and development; it attracts, and may kill when the water
becomes too hot or becomes chilled too  suddenly.   Colder  water
generally   suppresses   development.    Warmer  water  generally
accelerates activity and may be a primary cause of aquatic  plant
nuisances when other environmental factors are suitable.

Temperature  is a prime regulator of natural processes within the
water  environment.   It  governs  physiological   functions   in
organisms  and, acting directly or indirectly in combination with
other water quality constituents, it affects  aquatic  life  with
each  change.   These  effects  include  cheirical reaction rates,
enzymatic functions, molecular movements, and molecular exchanges
between membranes within and between  the  physiological  systems
and the organs of an animal.

Chemical  reaction  rates  vary  with  temperature  and generally
increase as the temperature  is  increased.   The  solubility  of
gases  in  water  varies  with  temperature.  Dissolved oxygen is
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decreased by the decay  or  decomposition  of  dissolved  organic
substances and the decay rate increases as the temperature of the
water  increases  reaching  a  maximum at about 30°C  (86°F) .  The
temperature of stream water, even during  summer,  is  below  the
optimum  for pollution-associated bacteria.  Increasing the water
temperature increases the bacterial multiplication rate when  the
environment is favorable and the food supply is abundant.

Reproduction  cycles  may  be  changed significantly by increased
temperature because this function takes  place  under  restricted
temperature  ranges.   Spawning  may  not  occur  at  all because
temperatures are too high.  Thus, a fish population may exist  in
a  heated  area  only by continued immigration.  Disregarding the
decreased reproductive potential,  water  temperatures  need  not
reach  lethal  levels  to  decimate a species.  Temperatures that
favor competitors, predators, parasites, and disease can  destroy
a species at levels far below those that are lethal.

Fish  food  organisms  are  altered  severely  when  temperatures
approach or  exceed  90°F.   Predominant  algal  species  change,
primary  production is decreased, and bottom associated organisms
may  be  depleted  or  altered   drastically   in   numbers   and
distribution.   Increased  water  temperatures  may cause aquatic
plant nuisances when other environmental factors are favorable.

Synergistic actions of pollutants are more severe at higher water
temperatures.  Given amounts of domestic sewage, refinery wastes,
oils,  tars,  insecticides,  detergents,  and  fertilizers   more
rapidly  deplete  oxygen in water at higher temperatures, and the
respective toxicities are likewise increased.

When water temperatures increase, the predominant  algal  species
may  change  from  diatoms  to  green  algae, and finally at high
temperatures to blue-green algae, because of species  temperature
preferentials.  Blue-green algae can cause serious odor problems.
The  number  and  distribution  of benthic organisms decreases as
water temperatures increase above 90°F, which  is  close  to  the
tolerance  limit for the population.  This could seriously affect
certain fish that depend on benthic organisms as a food source.
The cost of fish being attracted to heated water in winter months
may be considerable, due to fish mortalities that may result when
the fish return to the cooler water.

Rising  temperatures  stimulate  the  decomposition  of   sludge,
formation  of  sludge gas, multiplication of saprophytic bacteria
and fungi  (particularly in the presence of organic  wastes),  and
the   consumption  of  oxygen  by  putrefactive  processes,  thus
affecting the esthetic value of a water course.

In general, marine water temperatures do not change as rapidly or
range as widely as those of freshwaters.   Marine  and  estuarine
fishes,  therefore,  are  less tolerant of temperature variation.
Although this limited tolerance is greater in estuarine  than  in
open water marine species, temperature changes are more important
to  those  fishes  in  estuaries  and  bays than to those in open
                              71

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marine areas,  because of the nursery and replenishment  functions
of  the  estuary  that  can  be  adversely  affected  by  extreme
temperature changes.
                               72

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                           SECTION VII

                CONTROL AND TREATMENT TECHNOLOGY


                             SUMMARY

The waste load discharged from the independent rendering industry
to receiving streams can be reduced to desired levels,  including
no  discharge  of  pollutants, by conscientious water management,
in-plant waste controls, process revisions, and by the use  of  a
primary, secondary and tertiary waste water treatment.  Figure 12
is  a  schematic  of  a suggested waste reduction program for the
independent  rendering  industry  to  achieve  a   high   quality
effluent.

This  section  describes  many of the techniques and technologies
that are available or that are being  developed  to  achieve  the
various  levels  of waste reduction.  In-plant control techniques
and waste  water  management  suggestions  are  described  first.
Waste  treatment  technology normally used as a primary treatment
is  then  described.   In  the  case  of  the  offsite  rendering
industry,  this  "primary"  treatment  is  a  materials  recovery
process, and is  considered  as  part  of  the  in-plant  system,
although  many  of  these  systems  have  been improved to reduce
pollution  levels.   The  effluent  frcm  primary  treatment   is
considered the "raw waste."  Secondary treatment systems are used
in the treatment of the raw waste.

Each  treatment process is described, and the specific advantages
and disadvantages of each system, and the  effectiveness  on  the
specific  waste  water  contaminants found in rendering waste are
discussed.  The tertiary and advanced treatment systems that  are
applicable  to  the  waste  from  typical  rendering  plants  are
described in the last  part  of  this  section.   Some  of  these
advanced  treatment  systems have not been used on full scale for
rendering  plant  wastes;  therefore,  the  development   status,
reliability,  and  potential  problems  are  discussed in greater
detail than for the primary and secondary treatment systems  that
are in widespread use.
                   IN-PLANT CONTROL TECHNIQUES

The waste load from an independent rendering plant is composed of
a  waste water stream containing the various pollutants described
in Section VI.  The cost and effectiveness of  treatment  of  the
waste  stream  will vary with the quantity of water and the waste
load.  As indicated  in  Section  V,  the  pollutant  waste  flow
increases  with  plant  size,  and  is  higher  for  plants using
barometric leg  condensers.   In-plant  control  techniques  will
reduce both water use and waste load.  The former will be reduced
by  minimizing  the  entry  of raw materials into the waste water
stream, and the latter by cleanup procedures and frequency and by
the type of condensing system used.
                                73

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                             Figure 12.  Suggested Waste Reduction Program  for  Rendering Plants
Waste Reduction
  Techniques
Waste Reduction
    Effect
   Point  of
  Application
   Plant
Operations
                                                                                             Partial
                                                                                            Tertiary
                                                                                             Treat.
                                                                    Irrigation
                                                                    Evaporation
                                                                    Reirto va1 of
                                                                     fine Sus.
                                                                   So'ids. Salt,
                                                                    'hosphorus,
                                                                    V.'tnonia (as
                                                                    if c essary)
                                                                     r  9?.5%
                                                                       BOD
                                                                                                                \/

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The in-plant control techniques described below have been used in
offsite rendering plants or are technically feasible.


                          Condensables

Condensables typically are high in  BOD5,  phosphorus,  suspended
solids,  dissolved solids, TKN, ammonia, nitrates and grease  (see
Table 9).  However, a number of plants are able to  minimize  the
strength of Condensables in several ways.  These include:

     o    Avoid overloading cookers;
     o    Provide and maintain traps in the vapor lines;
     o    Control the speed of agitation;
     o    Provide by-pass valves for controlling pressure bleed-down
          on cookers used for hydrolyzing raw material;
     o    Control cooking rate.

The  volume  of  Condensables  is  dependent upon the type of raw
material being processed and on the type of condenser used.  From
the standpoint of waste treatment,  Condensables  should  not  be
diluted  with  fresh  water.   Treated  waters should be used for
operating barometric leg condensers.


             Control of High Strength Liquid Wastes

Liquid drainage from raw materials can  contribute  significantly
to  the total raw waste load.  These sources can be controlled or
eliminated by containing them and then mixing the  drainage  with
the  raw  materials  as  they enter a cooker, screening, or steam
sparging and screening.  Containing drainage may require plugging
drains in the raw materials receiving area and in wet wells below
receiving bins.

Blood water and tank  water,  both  of  which  are  high-strength
wastes (see Section V), can be eliminated by evaporating to stick
and  using  as  tankage  for dry inedible rendering.  Whole blood
drying processes do not generate any blood water  and  should  be
considered  as  an  alternative  method  to  steam  sparging  and
screening, followed by evaporation of blood water.


Hide curing waste waters are of high strength  (see Section V) and
can be a significant part of the  total  raw  waste  load.   This
source  can  be  eliminated by blending the hide curing wastes in
relatively small amounts with  raw  materials  being  charged  to
cookers.


                    Truck and Barrel Washings

Solids, including grease, should be scraped or squeegeed from the
trucks  and  barrels prior to washdown.  Truck washings should be
screened.


                                 75

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                          Odor Control

Although  odor  control  by   scrubbing   does   not   contribute
significantly  to the raw waste load, it can add significantly to
the waste water volume.  This large  contribution  to  the  waste
water  volume  can  be  avoided  by using chemicals and recycling
scrubbing water or by reusing treated water.


                    Plant Cleanup and Spills

Cleanup of the plant and spills should  include  dry  cleanup  by
squeegeeing  or  scraping  prior  to  washdown.  Plant cleanup is
usually required only once daily.  Accidental  spills  and  leaky
equipment  can, however, necessitate more frequent plant  cleanup.
Thus,  considerable effort should be expended to avoid spills  and
to prevent leaks.  A regularly scheduled maintenance program will
minimize  leaks;  it will minimize the spills caused by equipment
failure.

                   IN-PLANT PRIMARY TREATMENT

                        Flow Equalization

Equalization facilities consist of a  holding  tank  and  pumping
equipment designed to reduce the fluctuations of waste water flow
through  materials  recovery  systems.   They can be economically
advantageous, whether the industry is treating its own wastes  or
discharging  into  a  city  sewer  after  some pretreatment.  The
equalizing tank should have sufficient capacity  to  provide  for
uniform  flow  to  treatment facilities throughout a 24-hour day.
The tank is characterized by a varying flow into the tank  and   a
constant flow out.

The   major  advantages of equalization are that treatment systems
can be smaller since they can be designed for the 24-hour average
rather than the peak flows, and many  secondary  waste  treatment
systems  operate much better when not subjected to shock  loads or
variations in feed rate.

Many  plants do not require any  special  tanks  to  achieve flow
equalization  because  of  the manner in which they are operated.
For example, plants with large continuous systems or a number  of
batch systems   (10  to  20)  with  staggered cooking cycles that
operate most of the day are inherently achieving a  near-constant
flow  of waste water.

Screens

Since so  much  of  the  pollutant  matter  for  some sources  of
rendering  plant  wastes  is  originally  solid   (meat  and   fat
particles),  interception  of the waste material by various types
of  screens  is  a  natural  first  step.   To  assure  the best
performance  on a plant waste water stream, flow equalization  may
be needed preceding screening equipment.


                                 76

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Unfortunately, when the  pollutant  materials  enter  the  sewage
stream, they are subjected to turbulence, pumping, and mechanical
screening,  and they break down and release soluble BOD^ into the
stream, along  with  colloidal,  suspended,  and  greasy  solids.
Waste  treatment—that  is, the removal cf soluble, colloidal and
suspended  organic  matter—is  expensive.   It  is  usually  far
simpler and less expensive to keep the solids out of the sewer.

Static,  vibrating, and rotary screens are the primary types used
for this  step  in  the  in-plant  primary  treatment.   Whenever
possible,  pilotscale  studies  are  warranted before selecting a
screen, unless specific operating  data  are  available  for  the
specific  use  intended,  in the same solids concentration range,
and under the same operating conditions.
Static Screens

The primary function of a static screen is to  remove  "free"  or
transporting  fluids.   This can be accomplished in several ways,
and in most older concepts, only gravity drainage is involved.  A
concavely curved  screen  design  using  high  velocity  pressure
feeding  was  developed  and  patented  in the 1950's for mineral
classification and has been adapted to other uses in the  process
industries.   This  design employs bar interference to the slurry
which knives  off  thin  layers  of  the  flow  over  the  curved
surface.is

Beginning in 1969, United States and foreign patents were allowed
on  a  three-slope  static screen made of specially coined curved
wires.   This  concept  used  the  Coanda  or   wall   attachment
phenomenon to withdraw the fluid from the under layer of a slurry
which is stratified by controlled velocity over the screen.  This
method  of  operation  has  been  found to be highly effective in
handling slurries containing fatty or  sticky  fibrous  suspended
matter.1S
Vibrating Screens

The  effectiveness  of  a  vibrating  screen  depends  on a rapid
motion.  Vibrating screens operate between 99 rpm and  1800  rpm;
the  motion can be either circular or straight line, varying from
0.08 to 1.27 cm  (1/32 to 1/2 inch) total travel.  The  speed  and
motion are selected by the screen manufacturer for the particular
application.

Of prime importance in the selection of a proper vibrating screen
is the application of the proper cloth.  The capacities on liquid
vibrating  screens  are  based on the percent of open area of the
cloth.  The cloth is selected  with  the  proper  combination  of
strength  of  wire and percent of open area.  If the waste solids
to be handled are heavy and abrasive, wire of a greater thickness
and diameter should be used to assure long life.  However, if the
material is light or sticky in  nature,  the  durability  of  the
                                77

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screening  surface  may  be  the  least consideration.  In such a
case, a light wire may be desired to provide an increased percent
of open area.

Rotary Screens

One type of barrel or rotary screen, driven by external  rollers,
receives  the  waste  water  at  one  open end and discharges the
solids at the other open end.  The screen is inclined toward  the
exit  end  to  facilitate  movement of solids.  The liquid passes
outward through the screen (usually stainless steel screen  cloth
or  perforated  metal)  to  a receiver and then to the sewer.  To
prevent clogging, the screen is usually sprayed continuously by a
line of external spray nozzles.

Another rotary screen commonly used in various  industries,  such
as  the meat industry, is driven by an external pinion gear.  The
raw waste water is fed into the interior of the screen, below the
longitudinal axis, and solids are removed in a trough  and  screw
conveyor  mounted  lengthwise  at  the  axis  (center line) of the
barrel.  The liquid exits outward through the screen into a  tank
under  the   screen.   The  screen  is  partially  submerged in the
liquid in the tank.  The screen is usually 40 x 40 mesh, with 0.4
mm   (1/64  inch)  openings.   Perforated  lift  paddles   mounted
lengthwise   on the inside surface of the screen assist in lifting
the  solids to the conveyor trough.  This type is  also  generally
sprayed  externally  to  reduce blinding.  Grease clogging can be
reduced by coating the wire cloth with teflon.  Solids removal up
to 82 percent is reported.15

Applications

A broad range of applications exists for  screens as  the  first
stage  of in-plant waste water treatment.  These  include both the
plant waste  water and  waste  water  discharged   from  individual
sources,  especially streams with high solids content such as raw
material drainage.
                          Catch Basins

 The  catch basin for the separation  of  grease   and   solids   from
 independent  rendering  waste  waters was originally  developed to
 recover marketable  grease.   Since  the  primary  objective  was
 grease  recovery,  all  improvements  were  centered  on skimming.
 Many catch basins were not equipped with automatic bottom  sludge
 removal  equipment.   These  basins  could  often  be  completely
 drained to  the  sewer  and  were  "sludged   out"  weekly  or  at
 frequencies  such  that  septic  conditions   would  not cause the
 sludge to rise.  Rising sludge was undesirable  because  it  could
 affect the color and reduce the market value  of the grease.

 In the past twenty years, with waste treatment  gradually becoming
 an added economic incentive, catch basin design has been improved
 in   the  solids  removal  area  as well.  In  fact, the low market
                               78

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value of inedible grease and tallow  has  reduced  concern  about
quality  of the skimmings, and now the concern is shifting toward
overall effluent quality improvement.   Gravity  grease  recovery
systems  will  remove  20  to  30  percent  of the BOD5, 40 to 50
percent of the suspended solids, and 50  to  60  percent  of  the
grease  (hexane solubles).15

The majority of the gravity grease recovery basins (catch basins)
are  rectangular.   Flow rate is the most important criterion for
design; 30 to 40 minutes detention time at one-hour peak flow  is
a  common  design sizing factor.15  The use of an equalizing tank
ahead of the catch basin obviously minimizes the size requirement
for the basin.  A shallow basin—up to 1.8  meters   (6  feet)—is
preferred.

A "skimmer" skims the grease and scum off the top into collecting
troughs.   A  scraper  moves  the  sludge  at  the  bottom into a
submerged hopper from which it can be pumped or carries it up and
deposits it into a hopper.  Both  skimmings  and  sludge  can  be
recycled as a raw material for rendering.

Two  identical catch basins, with a common wall, are desirable so
operation can continue if one is down for maintenance or  repair.
Both concrete and steel tanks are used.

Concrete  tanks  have  the  inherent  advantages of lower overall
maintenance and more  permanence  of  structure.   However,  some
plants  prefer  to  be  able to modify their operation for future
expansion or alterations or  even  relocation.   All-steel  tanks
have  the  advantage  of  being  semipcrtable, more easily field-
erected, and more easily modified than concrete tanks.  The  all-
steel  tanks, however, require additional maintenance as a result
of wear from abrasion and corrosion.

A tank using all-steel walls and a concrete  bottom  is  probably
the  best  compromise  between  the  all-steel  tank and the all-
concrete tank.   The  advantages  are  the  same  as  for  steel;
however,  the  all-steel  tank  requires a footing underneath the
supporting members, whereas the concrete bottom forms  the  floor
and supporting footings for the steelwall tank.


                     Dissolved Air Flotation

This  system is, by definition, a primary treatment system; thus,
the effluent from a dissolved air flotation system is  considered
raw waste.  This system is normally used to remove fine suspended
solids  and  is  particularly  effective  on  grease in the waste
waters from independent rendering plants.   It  is  a  relatively
recent technology in the rendering industry; therefore, it is not
in  widespread  use,  although  increasing  numbers of plants are
installing these systems.

Dissolved air flotation appears to be the single  most  effective
device  currently  available  for  a  plant  to use to reduce the
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                           Compressed
                              Air
                  Feed
OD
O
                                                                                   Effluent
Totol  Pressurizotion
       Process
                                              Float
                                                                           V
                                                                         Sludge
                                    Figure  13.  Dissolved Air Flotation

-------
pollutant waste load in  its  raw  waste  water  stream.   It  is
expected that the use of dissolved air flotation will become more
common  in  the  industry,  especially as a step in achieving the
1983 standards.
Technical Description

Air flotation systems are used to remove any  suspended  material
from  waste water with a specific gravity close to that of water.
The dissolved air system generates a supersaturated  solution  of
waste  water  and air by pressurizing waste water and introducing
compressed air, then mixing the two in a  detention  tank.   This
"supersaturated"  waste  water  flows  to  a large flotation tank
where the pressure is released, thereby generating numerous small
air bubbles which effect the flotation of the  suspended  organic
material  by  one  of  three  mechanisms:  1) adhesion of the air
bubbles to the particles  of  matter;  2)  trapping  of  the  air
bubbles  in  the  floe  structures  of  suspended material as the
bubbles rise; and 3) adsorption of the air bubbles  as  the  floe
structure is formed from the suspended organic matter.16  In most
cases, bottom sludge removal facilities are also provided.

There   are   three  process  alternatives  that  differ  by  the
proportion of the waste water stream that is pressurized and into
which the compressed air is mixed.  In the  total  pressurization
process,  Figure  13,  the entire waste water stream is raised to
full pressure for compressed air injection.

In partial pressurization, Figure 14, only a part  of  the  waste
water  stream is raised to the pressure of the compressed air for
subsequent mixing.  Alternative A of Figure 14 shows a sidestream
of influent  entering  the  detention  tank,  thus  reducing  the
pumping  required  in  the  system  shown  in  Figure 13.  In the
recycle pressurization  process,  Alternative  B  of  Figure  14,
treated   effluent  from  the  flotation  tank  is  recycled  and
pressurized for mixing with the compressed air and then,  at  the
point  of  pressure  release,  is  mixed  with the influent waste
water.  Operating costs may vary slightly, but performance should
be essentially equal among the alternatives.

Improved performance of the air flotation system is  achieved  by
coagulation  of the suspended matter prior to treatment.  This is
done by pH adjustment or the addition cf coagulant chemicals,  or
both.  Aluminum sulfate, iron sulfate, lime, and polyelectrolytes
are used as coagulants at varying concentrations up to 300 to 400
mg/1  in  the raw waste.  These chemicals are essentially totally
removed in the dissolved air unit, thereby adding  little  or  no
load  to  the  downstream  waste treatment systems.  However, the
resulting float and  sludge  may  become  a  less  desirable  raw
material  for recycling through the rendering process as a result
of chemical coagulation addition.  Che -..Gal precipitation is also
discussed later, particularly in regard  to  phosphorus  removal,
under  tertiary treatment; phosphorus can also be removed at this
primary  (inplant)   treatment  stage.   A  slow  paddle  mix  will


                              81

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improve   coagulation.    It   has   been   suggested   that   the
pro+^inaceous matter in rendering plant waste could be removed by
reducing the pH of the waste water to the  isoelectric  point  of
about  3«5«lf>   The proteinaceous material would be coagulated at
that point and readily removed as  float  from  the  top   of   the
dissolved  air  unit.  This is not being done commercially in  the
rendering industry in the United States at the present time.

Similarly, the Alwatec process has been developed  by a company in
Oslo,  Norway,  using  a  lignosulfonic  acid  precipitation   and
dissolved air flotation to recover a high protein  product that is
valuable  as a feed.16 Nearly instantaneous protein precipitation
and hence, nitrogen removal, is achieved  when  a  high   protein-
containing  effluent  ia acidified to  a pH between 3 and  4 with a
high molecular weight  lignosulfonic   acid.   BOD5 reduction  is
reported  to  range  from 60 to 95 percent.  The effluent must be
neutralized before further treatment by the addition of   milk  of
lime   or  some  other  inexpensive alkali.  This process  is being
evaluated on meat packing waste in one plant in the United States
at  the present time.18

One of the manufacturers of  dissolved  air  flotation  equipment
indicated  a  60  percent  suspended   solids removal and  80 to 90
percent grease removal without the addition of  chemicals.  With
the  addition  of   300  to 400 mg/1 of inorganic coagulants and a
slow mix to  coagulate the organic matter, the  manufacturer says
that   90 percent or  more of the suspended solids and more than 90
  ercent of the grease can be removed.19  Total nitrogen reduction
>:^-: "sn 35 and 70   percent  was  found  in  dissolved  air units
surveyed in  the meat packing industry-8

North  Star's  staff  observed the operation of several dissolved
air units during the  verification  sampling  program  and plant
visits of   the  rendering and meat packing industries.   One meat
packing plant that  was visited controlled the feed rate  and pH of
the waste water and  achieved 90 to 95  percent removal  of  solids
and grease.  other  plants had relatively good operating  success,
but some did not  achieve  the  results  that   should  have been
attainable.   It  appeared that they did not fully understand  the
process chemistry and were using erroneous operating  procedures.

Problems and Reliability

The reliability of  the dissolved air flotation  process  and of  the
equipment seems to  be well established, although  it  is relatively
new technology for  the rendering industry.  As   indicated  above,
it   appears  that the use of the dissolved air system  is  not fully
exploited by some of the companies  who  have   installed  it   for
waste   water   treatment.   The  potential  reliability   of   the
dissolved air process can be realized  by proper  installation   and
operation.    The   feed  rate  and  process  conditions   must  be
maintained at the proper levels  at  all  times  to   assure  this
reliability.   This   fact does not  seem to be fully  understood or
of  sufficient concern to some companies, and thus  full  benefit is
frequently not achieved.


                              82

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                                                    Compressed
                                                        Air
                                                      ,	[Retention
                                                      f      V  Tank
                                                      I
                            Recycle Pressurizotion

                                    Process
                                 (Alternative B)
CO
CO
1
1
Feed from ,
Primary i fa >
Treatment j
i 	 ^(Retention ] 	 1

Flotation
Tank
1 1
• >v c
S C

L 	 	 ' rioai
V
Sludge
                                               Treated
                                               Effluent
                      Compressed
                          Air
Partial Pressurization
      Process
   (Alternative A)
                         Figure 14.   Process Alternatives for Dissolved Air Flotation

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The sludge and float taken from the  dissolved air  system can both
be recycled through  the  rendering   process.    The   addition  of
polyelectrolyte  chemicals  was   reported to create  some problems
for sludge dewatering and for subsequent use as   a  raw  material
for   rendering.    The  mechanical   equipment   involved  in  the
dissolved  air  flotation  system is  fairly  simple,   requiring
standard  maintenance  attention   for  such things   as pumps and
mechanical drives.

                  WASTE WATER TREATMENT SYSTEMS

The secondary treatment methods commonly used  for  the  treatment
of  rendering  plant  wastes  after   in-plant   primary  treatment
 (solids removal) are the following biological  systems:   anaerobic
process,  aerobic lagoons, and variations of the  activated  sludge
process.  Several of these systems are capable of providing up to
97  percent  BOD5  reductions  and  95 percent   suspended solids
reduction, as observed primarily  in  the meat   packing  industry.
Combinations  of  these  systems   can achieve  reductions up to 99
percent in BOD5 and grease, and up to  97   percent  in  suspended
solids  for rendering plant waste water.  Based  on operating data
from  a pilot-plant system on packing plant  wastes,  the  rotating
biological   contactor   also  shows  potential   as   a  secondary
treatment system.

The  selection of a secondary biological system for  treatment  of
rendering plant wastes  depends upon a number  of important system
characteristics.  Some of these are   waste   water  volume,  waste
load   concentration,    equipment   used,    pollutant   reduction
 effectiveness required,  reliability, consistency,  and  resulting
 secondary pollution  problems   (e.g., sludge  disposal and odor
control). The  characteristics and performance  of  each  of  the
above-mentioned   secondary treatment systems,  and also for common
 combinations of them, are described  below.   Capital and operating
costs are discussed  in  Section VIII.

                       Anaerobic  Processes

Elevated  temperatures  (29° to  35°C,  or  85°  to  95°F)   and  high
concentrations  of carbohydrates,  fats, proteins, and nutrients in
some   independent  rendering-plant  wastes  make these wastes well
 suited  to   anaerobic  treatment.    Anaerobic   or   facultative
microorganisms,  which   function   in  the   absence  of  dissolved
oxygen, break down the organic wastes to   intermediates  such  as
organic   acids  and  alcohols.  Methane bacteria then convert the
intermediates   primarily   to   carbon   dioxide   and   methane.
Unfortunately,  much  of  the  organic  nitrogen  present  in the
influent  is converted  to  ammonia  nitrogen.    Also,  if  sulfur
compounds are present  (such  as from  high-sulfate raw water—50 to
100   mg/1 sulfate),  hydrogen  sulfide will be generated.  Acid
conditions  are  undesirable   because   methane   formation   is
suppressed  and  noxious  odors develop.   Anaerobic processes are
economical because they  provide high overall removal of BOD5  and
suspended solids with no  power cost   (other than pumping) and with
                               84

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low  land  requirements.   Two  types  of anaerobic processes are
used: anaerobic lagoons and anaerobic contact systems.


Anaerobic Lagoons

Anaerobic lagoons are widely used in the  rendering  industry  as
the first step in secondary treatment or as pretreatment prior to
discharge  to a municipal system.  Reductions of up to 97 percent
in BOD5 and up to 95 percent in suspended solids can be  achieved
with  the  lagoons; 85 percent reduction is common.  Occasionally
two anaerobic lagoons are  used  in  parallel  and  sometimes  in
series.   These  lagoons  are  relatively deep (3 to 5 meters, or
about 10 to 17 feet), low surface area systems with typical waste
loadings of 240 to 320 kg BOD5/1000 cubic meters   (15  to  20  Ib
BOD5/1000 cubic feet)  and detention times of five to ten days.  A
thick  scum  layer of grease may accumulate on the surface of the
lagoon to retard heat loss, to ensure anaerobic  conditions,  and
hopefully  to  retain  obnoxious  odors.   Low  pH  and  wind can
adversely affect the scum layer.  Paunch manure and straw may  be
added  to  this  scum  layer but this would increase the nutrient
levels.

Plastic covers of nylon-reinforced Hypalon,  polyvinyl  chloride,
and  styrofoam  have been used on occasion by other industries in
place of the scum layer;  in  fact,  some  states  require  this.
Properly  installed  covers  provide  a convenient means for odor
control and collection of the by-product methane gas.

THe waste water flow inlet should be located near,  but  not  on,
the  bottom  of  the  lagoon.   In  some installations, sludge is
recycled to ensure adequate anaerobic seed for the influent.  The
outlet from  the  lagoon  should  be  located  to  prevent  short
circuiting of the flow and carry-over of the scum layer.

For  best  operation,  the  pH should be between 7.0 and 8.5.  At
lower pH, methane-forming bacteria will not survive and the  acid
formers  will take over to produce very noxious odors.  At a high
pH  (above 8.5), acid-forming  bacteria  will  be  suppressed  and
lower the lagoon efficiency.


Advantages/-Pi sadyant ages.   Advantages  of  an  anaerobic  lagoon
system are initial lew cost, ease of operation, and  the  ability
to  handle  large  grease  loads  and  shock waste loads, and yet
continue   to   provide   a   consistent   quality    effluent.20
Disadvantages  of  an  anaerobic  lagocn are the hydrogen sulfide
generated from sulfate-containing waters and the  typically  high
ammonia  concentrations  in the effluent of 100 mg/1 or more.  If
acid   conditions   develop,   severe   odor   problems   result.
Incidentally,  if the gases evolved are contained, it is possible
to use iron filings to remove sulfides.
                               85

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^BfiiiS^tionjE^,.  Anaerobic lagoons  used   as  the   first  stage  in
secondary  treatment  are  usually   followed   by aerobic lagoons.
Placing  a  small,  mechanically  aerated   lagoon   between   the
anaerobic  and  aerobic lagoons is  becoming popular.   A number of
meat packing plants are currently   installing extended  aeration
units  following  the  anaerobic lagoons to obtain nitrification.
Anaerobic lagoons are not permitted in  some states or areas where
the ground water is high  or  the   soil conditions  are  adverse
 (e.g., too porous) , or because of odor  problems.


Anaerobic Contact Systems

Anaerobic   contact   systems  require   far  more  equipment  for
operation than do anaerobic lagoons,  and  consequently  were  not
found  to  be used by the rendering industry.  However, their use
by  some  meat packing plants has demonstrated  their  applicability
to  rendering  plant  waste  waters  because  of  the similarity in
waste  characteristics.  The equipment,  as  illustrated  in  Figure
15,    consists  of  equalization  tanks,  digesters  with  mixing
equipment, air or vacuum gas stripping  units,  and  sedimentation
tanks   (clarifiers) .   Overall  reduction   of 90 to 97 percent in
BOD5  and suspended solids is achievable.

Equalized waste water flow is introduced into  a  mixed  digester
where  anaerobic decomposition takes place  at  a temperature of 33°
to  35°C  (90° to 95°F) .  BOD5 loading into  the digester is between
 2.4  and 3.2 kg/cubic meter  (0.15 and 0.20 Ib/cubic foot) and the
 detention time is between three  and  twelve   hours.    After  gas
 stripping,  the   digester  effluent  is clarified  and sludge is
 recycled at a rate of about  one-third   the  raw  waste  influent
 rate.    Sludge  is removed from the system at the rate of about 2
 percent  of the raw waste volume.

Advantages-Pi sadyantages^  Advantages of  the  anaerobic  contact
 system  are  high  organic  waste   load reduction in a relatively
 short time; production and collection of methane gas that can  be
 used   to maintain a  high temperature in the  digester and also to
 provide  auxiliary heat and  power;   good  effluent  stability  to
 grease  and  waste   load  shocks;   and application in areas where
anaerobic lagoons cannot be  used.    Disadvantages  of  anaerobic
contactors  are   higher  initial  cost   and maintenance costs and
 potential odor emissions from the clarifiers.
               Anaerobic  contact systems are restricted to use as
 the  first  stage  of  secondary treatment and can be followed by the
 same systems  as  follow anaerobic lagoons.
                                86

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oo
—I
         Plant

       Effluent
                 Equalizing Tank
                     A



                     w
Sludge Recycle
                               U/vA-
                            HeatersV/   V^y
                                     Anaerobic
                                     Digesters
         Gas

       Stripping

         Units
Sedimentation

   Tanks
                                   Effluent
                               Figure 15.  Anaerobic Contact Process

-------
                         Aerated Lagoons

Aerated lagoons have been used successfully for many  years   in  a
small number of installations treating meat packing and  rendering
plant   wastes.    However,   with  the  tightening   of   effluent
limitations,  and  because  aerated   lagoons  can   provide   the
additional treatment, the number of installations  is  increasing.

Aerated   lagoons   use   either  fixed  mechanical   turbine-type
aerators, floating propeller-type aerators,   or  a diffused air
system  for  supplying  oxygen  to  the waste water.   The lagoons
usually are 2.4 to 4.6 meters  (8 to 15 feet)  deep,   and  have  a
detention time of two to ten days.  BOD5 reductions range from  40
to  60  percent, with little or no reduction  in  suspended solids.
Because of this, aerated lagoons approach  conditions   similar   to
extended aeration without sludge recycle  (see below).
Advantages-Di sadvantages

Advantages  of  this system are that  it  can  rapidly add dissolved
oxygen  (DO) to convert anaerobic  effluent  to  an  aerobic  state;
provide  additional  BOD5 reduction;  and it  requires a relatively
small   amount  of  land.    Disadvantages    include   the   power
requirements  and  the   fact  that the aerated lagoon, in itself,
usually  does not reduce  BOD5 and  suspended solids   adequately  to
be   used  as  the  final  stage   in   a high  performance secondary
system.


Applications

Aerated  lagoons  are  usually  the  first  or  second  stages  of
secondary   treatment,  and  must  be followed by aerobic (shallow)
lagoons  to reduce  suspended solids and to  provide  the  required
final treatment.


                         Aerobic  Lagoons

Aerobic  lagoons   (stabilization  lagoons  or oxidation ponds)  are
large surface area, shallow lagoons,  usually 1 to  2.3  meters   (3
to   8   feet)  deep,  loaded at a  BOD5 rate of 20 to 50 pounds  per
acre.   Detention times vary from  about one month to six or  seven
months;  thus, aerobic lagoons require large  areas  of land.

Aerobic  lagoons serve three main  functions in waste reduction:

     o     Allow solids to settle  out;

     o     Equalize and control flow;

     o     Permit stabilization of organic  matter by aerobic and
           facultative microorganisms  and also by algae.

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Actually,  if  the  pond is quite deep, 1.8 to 2.4 meters.(6 to 8
feet), the waste water near the bottom may be void  of  dissolved
oxygen  and  anaerobic  organisms  may  be  present.   Therefore,
settled solids can be decomposed into inert and  soluble  organic
matter by aerobic, anaerobic, or facultative organisms, depending
upon  the  lagoon conditions.  The soluble organic matter is also
decomposed  by  microorganisms.   It  is  essential  to  maintain
aerobic  conditions in at least the upper six to twelve inches in
shallow lagoons, since  aerobic  microorganisms  cause  the  most
complete  removal  of  organic  matter.   Wind  action assists in
carrying  the  upper  layer  of  liquid   (aerated  by   air-water
interface and photosynthesis) down into the deeper portions.  The
anaerobic   decomposition   generally  occurring  in  the  bottom
converts solids to liquid organics, which  can  become  nutrients
for the aerobic organisms in the upper zone.

Algae  growth  is  common in aerobic lagoons; this currently is a
drawback when  aerobic  lagoons  are  used  for  final  treatment
because the algae appear as suspended solids and contribute BOD5.
Algae  added to receiving waters are thus considered a pollutant.
Algae in the effluent may be reduced by drawing  off  the  lagoon
effluent  at  least  30  cm   (about 14 inches) below the surface,
where concentrations are usually lower.   Algae  in  the  lagoon,
however,  play an important role in stabilization.  They use CO2,
sulfates, nitrates, phosphates, water and sunlight to  synthesize
their  own  organic  cellular  matter  and  give off oxygen.  The
oxygen may  then  be  used  by  other  microorganisms  for  their
metabolic  processes.  However, when algae die they release their
organic matter in the lagoon, causing a secondary loading.

Ammonia disappears without the appearance of an equivalent amount
of nitrite and nitrate in aerobic lagoons  as  evidenced  by  the
results  of  our  field sampling survey.  From this, and the fact
that aerobic lagoons tend to become anaerobic near the bottom, it
appears that considerable denitrification can occur.

Ice  and snow cover in winter reduces the overall effectiveness of
aerobic lagoons by reducing algae  activity,  preventing  mixing,
and  preventing  reaeration  by  wind action and diffusion.  This
cover, if present for an extended period, can result in anaerobic
conditions.  When there is no ice and snow cover on large aerobic
lagoons, high winds can develop a strong  wave  action  that  can
damage  dikes.   Riprap,  segmented lagcons, and finger dikes are
used  to  prevent  wave  damage.   Finger  dikes,  when  arranged
appropriately,  also  prevent short circuiting of the waste water
through  the  lagoon.   Rodent  and  weed   control,   and   dike
maintenance are all essential for good operation of the lagoons.


Advantages-Di sadvantages

Advantages  of aerobic lagoons are that they reduce the suspended
solids and colloidal matter, and oxidize the  organic  matter  of
the  influent  to  the  lagoon; they also permit flow control and
waste water storage.   Disadvantages  are  reduced  effectiveness
                              89

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during winter months that may require no discharge for periods of
three  months  or  more,  the  large land requirements, the  algae
growth problem leading  to  higher  suspended  solids,  and  odor
problems  for  a  short  time  in spring, after the ice melts and
before the lagoon becomes aerobic again.


Applications

Aerobic lagoons usually are the last stage in  secondary treatment
and  frequently  follow   anaerobic   or   anaerobic-plus-aerated
lagoons.   Large  aerobic  lagoons  allow  plants  to  store  waste
waters for discharge during periods of high flow in the receiving
body of water or to store  for  irrigation  purposes   during the
summer.   These  lagoons  are particularly popular in  rural  areas
where land is available and relatively inexpensive.


                        Activated Sludge

The conventional activated sludge process is schematically   shown
in  Figure   16.   In  this  process  recycled  biologically active
sludge or floe is mixed in aerated tanks  or   basins   with   waste
water.  The  microorganisms in the floe adsorb  organic  matter from
the  wastes   and  convert  it by oxidation-enzyme systems to such
stable products as carbon dioxide, water, and  sometimes  nitrates
and  sulfates.   The  time  required for digestion depends on the
type of waste and its concentration, but the average time is six
hours.  The  floe, which is a mixture of microorganisms (bacteria,
protozoa,  and  filamentous types)„ food, and  slime material, can
assimilate organic matter rapidly when properly  activated; hence,
the  name  activated sludge.

From  the  aeration tank, the mixed  sludge  and  waste  water,  in
which  little  nitrification has taken place,  are discharged to a
sedimentation tank.  Here the sludge  settles  out,  producing  a
clear  effluent, low in BOD5 and a biologically  active sludge.  A
portion of the settled  sludge,  normally  about   20  percent,  is
recycled  to serve  as  an inoculum and to maintain a high  mixed
liquor  suspended  solids  content.   Excess   sludge   is  removed
 (wasted)  from the system, to thickeners and anaerobic digestion,
to   chemical treatment   and   dewatering   by   filtration  or
centrifugation or to land disposal where it is used as fertilizer
and  soil  conditioner to aid secondary crop growth.

This  conventional  activated  sludge process  can reduce  BOD5  and
suspended solids up to  95 percent.  However,   it cannot   readily
handle  shock  loads and widely varying flows  and therefore  might
require upstream flow equalization.

Various modifications of the activated sludge  process   have   been
developed,   such  as the tapered aeration, step  aeration,  contact
stabilization,  and  extended  aeration.   Of    these,   extended
aeration  processes  are most frequently being used  for treatment
of meat processing, meat packing and rendering wastes.


                               90

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 Raw
Waste
             Primary
         Sedimentation
                              Secondary
                            Sedimentation
         Aeration Tank
                        |_Return_ Activated Sludge
Effluent
Waste
Sludge
                                              Waste I
                                             Sludge^
             Figure  16.  Activated Sludge Process

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Extended Aeration

The extended aeration process  is  similar  to   the   conventional
activated  sludge  process,  except that the  mixture  of activated
sludge and raw materials is maintained  in  the   aeration  chamber
for longer periods of time.  The usual  detention time in extended
aeration  ranges from one to three days, rather  than  six hours  as
in the  conventional  process.   During this prolonged  contact
between  the  sludge  and  raw waste, there is ample  time for the
organic matter to be adsorbed by the  sludge  and  also  for the
organisms  to  metabolize  the  organic matter   which  they have
adsorbed.  This allows for a  much  greater   removal   of  organic
matter.  In addition, the organisms undergo a considerable amount
of  endogenous  respiration,  and  therefore  oxidize much of the
organic matter which has been built up  into the  protoplasm of the
organism.  Hence, in addition to high organic removals  from the
waste  waters,  up  to  75  percent  of the organic matter of the
microorganisms   is   decomposed   into   stable   products  and
consequently less sludge will have to be handled.

In  extended  aeration,  as  in the conventional activated sludge
process, it is necessary to  have  a  final   sedimentation  tank.
Some   of  the  solids resulting from extended aeration are rather
finely divided and therefore settle slowly,   requiring  a  longer
period of settling.

The   long  detention  time in the extended aeration tank makes  it
possible for nitrification  to  occur.   In   nitrification  under
aerobic conditions, ammonia is converted to nitrites  and nitrates
by specific groups of nitrifying bacteria.  For  this  to occur,  it
is  necessary  to  have  sludge  detention times in excess of ten
days. 20  This can be accomplished by regulating   the   amounts  of
recycled and wasted sludge.  Oxygen-enriched  gas could be used  in
place  of   air   in  the  aeration  tanks   to   improve  overall
performance.  This  would  require  that   the aeration  tank  be
partitioned   and  covered,  and  that  the   air  compressor and
dispersion system be replaced by a rotating sparger system.  When
cocurrent, staged flow and recirculation of gas  back  through the
liquor are  employed,  between  90  and 95 percent oxygen use  is
claimed.  Although this modification of extended aeration has not
been  used in treating rendering plant wastes, it  is   being  used
successfully for treating other wastes.


Adyantages~Disadvantages._    The   advantages   of  the  extended
aeration process are that it is immune  to  shock  loading and  flow
fluctuations  because  the  incoming raw waste load is diluted  by
the liquid in the system to a much greater  extent  than  in the
conventional   activated  sludge.   Also,  because  of  the  long
detention time, high BOD5  reductions   can be   obtained.   Other
advantages  of the system are the elimination of sludge digestion
equipment and the capability to  produce   a   nitrified  effluent.
Disadvantages  are  that  it  is  difficult to remove most of the
suspended solids  from  the  mixed   liquor discharged  from  the
aeration  tank;  large  volume  tanks   or  basins are required to
                              92

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accommodate the long detention times;  and  operating  costs  for
aeration are high.

Applications^   Because  of  the  nitrification process, extended
aeration systems are being  used  by  some  industries  following
anaerobic  processes  or  lagoons  to  produce  low  BOD5 and low
ammonia-nitrogen effluents.  They are  also  being  used  as  the
first   stage  of  secondary  treatment,  followed  by  polishing
lagoons.
                  Rotating Biological Contactor

Process Description

The rotating biological contactor (RBC)  consists of a  series  of
closely  spaced  flat  parallel  disks  which  are  rotated while
partially immersed in waste waters being treated.   A  biological
growth covering the surface of the disk adsorbs dissolved organic
matter  present  in  the waste water.  As the biomass on the disk
builds up, excess slime  is  sloughed  off  periodically  and  is
settled  out  in  sedimentation  tanks.  The rotation of the disk
carries a thin film of waste water into the air where it  absorbs
the  oxygen  necessary for the aerobic biological activity of the
biomass.  The disk rotation also  promotes  thorough  mixing  and
contact  between  the biomass and the waste waters.  In many ways
the RBC system is a compact version of a  trickling  filter.   In
the  trickling  filter,  the waste waters flow over the media and
thus over the microbial flora; in the RBC system,  the  flora  is
passed through the waste water.

The system can be staged to enhance overall waste load reduction.
Organisms  on the disks selectively develop in each stage and are
thus particularly adapted to the composition of the waste in that
stage.  The first stages might be used for removal  of  dissolved
organic  matter,  while  the  latter  stages  might be adapted to
nitrification of ammonia.

Development Status

The RBC system was developed  independently  in  Europe  and  the
United  States about 1955 for the treatment of domestic waste; it
found application only in Europe, where there  are  an  estimated
1000  domestic  installations.20  However, the use of the RBC for
the treatment of meat plant  waste  is  being  evaluated  at  the
present  time.   The  only operating information available on its
use on meat  packing  waste  is  from  a  pilotscale  system;  no
information  appears  to  be  available  on  its use for treating
rendering plant wastes.  The pilot-plant studies  were  conducted
with  a four-stage REC system with four-foot diameter disks.  The
system was treating a portion of the effluent  from  the  Austin,
Minnesota,  anaerobic  contact  plant  used to treat meat packing
waste.  These results showed a  BOD5  removal  in  excess  of  50
percent,  with  loadings less than 0.037 kg BOD5 per unit area on
an  average  BOD5  influent  concentration  of  approximately  25
mg/1.2i


                                93

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Data  from  Autotrol  Corporation,  one  of  the suppliers  of RBC
systems, revealed ammonia removal of greater than  90   percent  by
nitrification  in  a  multistage unit.21  Four to  eight  stages of
disks with maximum hydraulic loadings of 61 liters per   day  per
square  meter  (1.5 gallons per day per square foot)  of  disk area
are considered normal for ammonia removal.

A large installation was recently  completed  at   the Iowa Beef
Processors  plant  in  Dakota  City,  Nebraska,  for   the further
treatment of the effluent from an anaerobic  lagoon.22   No data
are  available  on this installation, which has been  plagued with
mechanical problems.

Advantages-Disadvantages

The major advantages of the RBC system  are  its   relatively  low
first  cost;  the  ability  to  stage to obtain dissolved organic
matter reduction with the potential for  removal   of   ammonia  by
nitrification;  and its good resistance to hydraulic  shock  loads.
Disadvantages are that the system should be housed, if located in
cold climates, to  maintain  high  removal  efficiencies and  to
control   odors.   Although  this  system  has  demonstrated  its
durability and  reliability  when  used  on  domestic wastes  in
Europe, it has not yet been proved on rendering plant wastes.
Uses

Rotating  biological  contactors  could  be   used   for the entire
aerobic secondary system.  The number of stages  required  depend
on  the  desired  degree  of treatment and the influent strength.
Typical  applications  of  the  rotating  biological   contactor,
however,  may  be   for  polishing   the  effluent   from  anaerobic
processes, and as pretreatment prior to discharging wastes  to  a
municipal  system.   A BOD5 reduction of 98  percent is reportedly
achievable with a four-stage RBC.20


       Performance  of Various Secondary Treatment  Systems

Table  13 shows BOD5, suspended solids  (SS) ,   and   grease  removal
efficiencies   for   various   biological  treatment  systems  on
rendering plant and meat packing plant waste waters.    Exemplary
values each  represent  results from an actual treatment system,
except for the data on the anaerobic plus aerobic   lagoon  system
under  treatment on meat packing waste waters, which includes two
plants.

The number of systems used to calculate average values  is  shown
in  Table  13.   It is  apparent that the anaerobic plus aerobic
lagoon system is the one most commonly used  by meat  packing  and
rendering plants.

The  estimated  reduction  of  BOD5  for meat packing waste waters
shown  for the anaerobic lagoon plus  rotating biological contactor
                               94

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  Table  13.  Performance of Various  Secondary Treatment Systems
CO
+J
C
CO
rH
PL.
M
n
•H
(-1
0)
T3
C
(1)
P3
Secondary Treatment System
(number of systems used
to determine averages)

Anaerobic + Aerobic
Lagoon (4)
Activated Sludge (2)


Aerated + Aerobic
Lagoon (2)
Anaerobic + Aerobic
Lagoon (22)
Anaerobic + Aerated +
Aerobic Lagoon (3)
Anaerobic Contact Process +
Aerobic Lagoon (1)
co
CO
.u
C
nJ
PM
w
c
•H
^1
O
cd
fi .
M-t
4-1
0)
0)
S
Extended Aeration +
Aerobic Lagoon (1)

Anaerobic Lagoon + Rotating
Biological Contactor


Anaerobic Lagoon + Extended
Aeration + Aerobic Lagoon


Anaerobic Lagoon +
Trickling Filter (1)
2-Stage Trickling Filter (1)
Aerated + Aerobic
Lagoon (1)
Anaerobic Contact (1)
Water Wasteload Reduction, Percent
Ave
BOD 5


97.7
93.7



96.9

95.4

98.3

98.5


96.0


98. 5e



98e



97.5
95.5

99.4
96.9
rage V<
SS


97.3
86.1



88.2

93.5

93.3

96.0


86.0


—



93e



94.0
95.0

94.5
97.1
alues
Grease


89.2
92.2



77.5

95.3

98.5

99.0


98.0






98e



96.0
98.0

—
95.8
Exem
BOD 5


99.0
96.6



97.7

98.9

99.5




96.0













99.4
96.9
Diary \
SS


99.9
97.1



93.8

96.6

97.5




86.0













94.5
97.1
ralues
Grease


99.4
99.4



78.8

98.9

99.2




98.0













	
95.8
e = estimated
                             95

-------
is based on preliminary pilot-plant results.   The  values   shown
for  the anaerobic-lagoon plus extended aeration system  are  based
on estimates of their combined effectiveness that are  below the
value  calculated by using the average removal efficiency for the
two components of the system, individually.  For example, if the
BOD5 reduction for the anaerobic lagoon and the extended aeration
were  each  90  percent,  the  calculated  efficiency  of the two
systems combined would be 99 percent.

The data of  Table  13  show  that,  for  rendering  plants,  the
anaerobic  plus  aerobic lagoons are the most effective  system of
those studied for BOD5, SS, and grease removal.  Furthermore, the
anaerobic  plus  aerobic  lagoon  system  appears,   by   percent
reductions,  to  be  more  effective  en  rendering  than on meat
packing waste waters.  This conclusion could be the result of  an
insufficient  number  of observations; however, it most  likely is
because the rendering waste loadings in the treatment  system were
frequently low.  In fact, the BOD5 waste loadings to this type of
system for three of the rendering plants were 12.8; 125, and 35.3
kg BOD5/1000 cubic meters  (15 to 20  Ib  BOD5/1000  cubic  feet).
All  of  the  secondary  treatment systems listed in Table 13 are
capable of treating typical rendering plant  waste  waters   to  a
degree  sufficient  to  meet  the  1977  standards recommended in
Section IX.  These systems, equipped with a sand  filter or its
equivalent,  are  also capable of producing a final effluent that
would meet the 1983 standards recommended in Section X.  In  fact,
the data presented in Section X show that at least three of  these
systems alone—anaerobic plus aerobic lagoon,  activated sludge,
or  aerated  plus aerobic lagoon--are already producing  rendering
plant effluent that meets the  majority  of  pollutant  parameter
limitations for 1983.
                 TERTIARY AND ADVANCED TREATMENT

                     Chemical Precipitation


Phosphorus  is  an  excellent  nutrient  for  algae   and  thus can
promote heavy algae blooms.  As such,  it  cannot  be  discharged
into  receiving  streams,  and  its  concentration   should  not be
allowed to build up in a  recycle  water  stream.    However,  the
presence  of  phosphorus is particularly useful in spray  or flood
irrigation systems as a nutrient for plant growth.

The  effectiveness  of  chemical   precipitation   for    removing
phosphorus. Figure 17, has been verified in full scale  during the
North  star  verification  sampling  program  of the meat packing
industry.a  One packing plant operates a dissolved air  flotation
system  as  a chemical precipitation unit and achieves  95 percent
phosphorus removal, to a concentration of less than  1 mg/1.

Chemical  precipitation  can  be  used  for  primary   (in-plant)
treatment  to  remove  BOD5,  suspended  solids,  and  grease,  as
discussed earlier in conjunction with  dissolved  air  flotation.


                                96

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Also,   it  can  be used as a final treatment following biological
treatment to remove suspended solids in addition to phosphorus.

Technical Description

Phosphorus occurs in waste water streams  from  rendering  plants
primarily  as  phosphate  salts.   Phosphates can be precipitated
with trivalent iron and trivalent aluminum salts.  It can also be
rapidly precipitated by the addition of lime; however,  the  rate
of removal is controlled by the agglomeration of the precipitated
colloids   and   by  the  settling  rate  of  the  agglomerate.16
Laboratory investigation and experience with in-plant  operations
have  substantially confirmed that phosphate removal is dependent
on pH and that this removal tends to be limited by the solubility
behavior of the three  phosphate  salts—calcium,  aluminum,  and
iron.    The  optimum  pH  for the iron and aluminum precipitation
occurs in the 4 to 6 range,  whereas  the  calcium  precipitation
occurs on the alkaline side at pH values above 9.5.

Since  the  removal of phosphorus is a two-step process involving
precipitation and then agglomeration, and both are  sensitive  to
pH,  controlling  the pH level takes on added significance.  If a
chemical other than lime is used in the precipitation-coagulation
process, two levels of pH are required.  Precipitation occurs  on
the acid side and coagulation is best carried out on the alkaline
side.     The  precipitate  is  removed  by  sedimentation  or  by
dissolved air flotation.16

Polyelectrolytes  are  polymers  that  can  be  used  as  primary
coagulants,   flocculation  aids,  filter  aids,  or  for  sludge
conditions.  Phosphorus removal may be enhanced  by  the  use  of
such polyelectrolytes by producing a better floe than might occur
without such chemical addition.23

The  chemically  precipitated  sludge contains grease and organic
matter in addition to the phosphorus, if the system  is  used  in
primary  treatment.  If it is used as a post-secondary treatment,
the sludge volume will be less  and  it  will  contain  primarily
phosphorus  salts.   The  sludge  from  either  treatment  can be
landfilled.
Development Status

This process is well  established  and  understood,  technically.
However,  its  use on rendering plant waste waters, normally  as  a
primary waste treatment  system,  is  very  limited  and   is   not
expected  to  gain  widespread  acceptance.  This  is because  most
rendering plants do not have  high  phosphorus   levels  in their
total  waste  waters  and  have other effective  primary treatment
processes for BOD5, S3, and grease removal.
                                97

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Problems and Reliability As indicted above,  the  reliability  of
this  process  is  well  established;  however,  it  is  a  chemical
process  and  as  such  requires  the  appropriate   control   and
operating  procedures.   The  problems that can be encountered in
operating this process are frequently the result  of a  lack  of
understanding  or  inadequate  equipment.  Sludge disposal  is not
expected to be a problem, although the  use  of  polyelectrolytes
and  their  effect on the dewatering properties of the  sludge are
open to some question at the present time.  In addition,  the  use
of  the  recovered  sludge as a raw material for rendering  may be
less desirable as a result of chemical addition.
                           Sand Filter

A slow sand filter is a specially prepared bed of  sand   or   other
mineral  fines  on  which doses of waste water are intermittently
applied and from which effluent is removed by  an   under-drainage
system   (Figure  18);  it  removes  solids   from   the waste water
stream.  BOD5 removal occurs  primarily  as  a  function of  the
degree  of solids removal, although some biological action  occurs
in the top inch or two of sand.  Effluent from the sand filter is
of a high quality, with BOD5 and suspended solids   concentrations
of  less  than  10  mg/1.24   Although  the  performance of  a sand
filter is well known and documented, it is not in  common use  be-
cause it is not needed to reach current waste water standards.

A rapid  sand filter may operate under pressure in  a closed  vessel
or  may be built in open concrete tanks.  It is primarily a water
treatment device and thus would be used  as  tertiary   treatment,
following secondary

                                               Float
Primary
or
Qopnnflnrv ^>
Treatment
Effluent

pH
Ajustment

N
s>

Chemical
Addition

\
j>
/
^
Air
Flotation
System

Partial
- — - • 	 ^> lemury
Treated
Effluent
                                                      V
                                                   Sludge
       Figure 17.   Chemical Precipitation Schematic
treatment.   Mixed  media  filters   are  special versions of rapid
sand filters that permit deeper bed-penetration by  gradation  of
particle  sizes  in  the  bed.   Up-flow filters are also special
cases of rapid filters.

                                 98

-------
                                       Figure 18.  Sand Filter System
                Primary  or
                Secondary
                 Effluent
IO
                                                             Chlorination,
                                                               Optional
                                                             for Odor Control
                                                                             ^L.
                                                                                   Effluent
                                                 Surface nr  Back
                                                  Clean      Wash
                                                   to Regenerate

-------
Technical Description

The slow sand filter removes solids primarily at the  surface  of
the  filter.  The rapid sand filter is operated to allow a deeper
penetration of suspended solids into the  sand  bed  and  thereby
achieve  solids  removal  through  a greater cross section of the
bed.  The rate of filtration of the rapid filter  is  up  to  100
times  that  of the slow filter.  Thus, the rapid filter requires
substantially less area than the slow filter; however, the  cycle
time  averages  about 2U hours in comparison with cycles of up to
30 to 60 days for a slow filter.25  The larger area required  for
the latter means a higher first cost.  For small plants, the slow
sand filter can be used as secondary treatment.  In larger sizes,
the  labor  in  maintaining and cleaning the surface may mitigate
its use.  The rapid sand filter, on the other hand, can  be  used
following   secondary  treatment.   However, it would tend to clog
quickly  and require frequent backwashing,  resulting  in  a  high
water use,  if used as secondary treatment.  This wash water would
also  need  treatment  if  the  rapid  sand  filter  were used in
secondary   treatment  with  only  conventional   solids   removal
upstream in the plant.

The  rapid  filters  operate essentially unattended with pressure
loss controls and piping  installed  for  automatic  backwashing.
They are contained in concrete structures or in steel tanks.23

Cleanup  of the rapid sand filter requires backwashing of the bed
of  sand  with  a greater quantity of water than used for  the  slow
sand  filter.   Backwashing is an effective cleanup procedure and
the only constraint is to irinimize the  wash  water  required  in
cleanup,  since  this  must  be  disposed  of in some appropriate
manner other  than discharging it to a stream.


Development Status

The slow sand filter has been in use for 50 years and  more.   It
has  been   particularly  well suited to small cities and isolated
treatment systems serving hotels, motels, hospitals, etc.,  where
treatment   of  low  flow  is  required  and  land  and  sand  are
available.  Treatment in these applications has been of sanitary-
or  municipal-type raw waste.  The Ohio  Environmental  Protection
Administration  is  a  strong  advocate of slow sand filters as  a
secondary treatment for small meat plants, following some form of
settling or solids removal.  As of early 1973,  16  sand  filters
had  been   installed  and  eight were proposed and expected to be
installed in  Ohio.  All 24 of these installations were  on  waste
from  meat  plants.26 The land requirements for a slow sand filter
are not  particularly significant in relation  to  those  required
for   lagooning   purposes   in  secondary  treatment  processes.
However, the quality and quantity of sand is important and may be
a constraint  in the use of sand filters in some local situations.
It  should also be recognized  that  this  process  requires  hand
labor  for  raking  the  crust  that  develops  on  the  surface.
                                 TOO

-------
Frequency of raking may be weekly or monthly, depending upon  the
quality of pretreatment and the gradation of the sand.


Problems and Reliability

The  reliability  of  the  slow  sand  filter  seems  to  be well
established in its long-term use as a municipal  waste  treatment
system.   When  the  sand filter is operated intermittently there
should be  little  danger  of  operating  mishap  with  resultant
discharge  of  untreated  effluent or poor quality effluent.  The
need for bed cleaning  becomes  evident  with  the  reduction  in
quality  of  the effluent or in the increased cycle time, both of
which are subject to monitoring and control.  Operation  in  cold
climates is possible as long as the appropriate adjustment in the
surface  of the bed has been made to prevent blanking off the bed
by freezing water.

Chlorination, both before and after sand filtering,  particularly
in  the  use  of  rapid  filters, may be desirable to minimize or
eliminate potential odor  problems  and  slimes  that  may  cause
clogging.

The  rapid  sand  filter  has  been  used  extensively  in  water
treatement plants and in municipal sewage treatment for  tertiary
treatment;  thus,  its  use  in  tertiary  treatment of secondary
treated effluents from rendering plants appears to be a practical
method of reducing BOD5 and  suspended  solids  to  levels  below
those expected from conventional secondary treatment.

                    Microscreen-Microstrainer

A  microstrainer  is  a  filtering  device  that uses a fine mesh
screen on a partially submerged rotating drum to remove suspended
solids and thereby reduce the BOD5 associated with those  solids.
Figure  19.   The  microstrainer  is used as a tertiary treatment
following the removal of most of the solids from the waste  water
stream, and suspended solids and BOD5 have been reduced to 3 to 5
mg/1  in  applications on municipal waste.16 There are no reports
of their use in the tertiary treatment of rendering plant wastes.


Technical Description

The microstrainer is a filtration device  in  which  a  stainless
steel  microfabric  is  used  as the filtering medium.  The steel
wire cloth is mounted on the periphery of a drum which is rotated
partially submerged in the  waste  water.   Backwash  immediately
follows  the  deposition  of  solids  en  the  fabric, and in one
installation, this is followed by ultraviolet light  exposure  to
inhibit  microbiological growth.16  The backwash water containing
the solids amounts to about 3 percent of the waste  water  stream
and  must be disposed of by recycling to the biological treatment
system.27  The drum is rotated at a minimum of 0.7 and  up  to  a
maximum  of  4.3 revolutions per minute.16  The concentration and


                              101

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percentage removal performance  for  micros-trainers  on  suspended
solids  and  BOD5 appear to be  approximately the same as for  sand
•F-i 1 +- o-t-c: .
filters.
Development Status

while there is general information available on  the  performance
of  microstrainers  and on tests  involving the use of them, there
appears to be only one recorded installation of  a  microstrainer
in use on municipal  waste;  the requirements for effluent quality
have not
necessitated such installation.   The economic comparisons between
sand  filters and microstrainers  are inconclusive; the mechanical
equipment required for the microstrainer may be a greater  factor
than  the  land  requirement  for  the sand filter at the present
time.
       Secondary
       Treatment
        Effluent
Backwash  to
    Clear Screen/Strainer
                                                      Tertiary
                                                      Treated
                                                      Effluent
                       Figure 19. Microscreen/Microstrainer
                                 102

-------
Problems and Reliability

The test performance of the microstrainer fairly well establishes
the reliability of the device and its ability to remove suspended
solids and associated BOD5.  Operating and  maintenance  problems
have  not been reported; this is probably because, in large part,
of the limited use of the device in full-scale applications.   As
a mechanical filtration device requiring a drive system, it would
have normal maintenance requirements associated with that kind of
mechanical  equipment.   As  a device based on microopenings in a
fabric, it would be particularly  intolerant  to  any  degree  of
grease loading.

                  Nitrification-Denitrification

This  two-step  process  of  nitrification  and  denitrification,
Figure 20, is a system to remove the nitrogen  which  appears  as
ammonia  in  treated  rendering  plant waste waters, and it is of
primary importance  for  removal  of  the  ammonia  generated  in
anaerobic   secondary  treatment  systems.   Ammonia  removal  is
becoming more important because of stream standards being set  at
levels  as  low  as 1 to 2 mg/1.  Removal of ammonia is virtually
complete, with the nitrogen gas as the end product.


Technical Description

The  large  quantities  of  organic  matter  in  raw  waste  from
rendering   plants  is  frequently  and  effectively  treated  in
anaerobic lagoons.  Much of the nitrogen in the  organic  matter,
present  mainly  as protein, is converted to ammonia in anaerobic
systems or in localized anaerobic  environments.   The  following
sets  of  equations  indicate the nitrification of the ammonia to
nitrites and nitrates, followed by the subsequent denitrification
to nitrogen and nitrous oxide.28  The responsible  organisms  are
also indicated.

Nitrification  does  not  occur to any great extent until most of
the carbonaceous material has been removed from the  waste  water
stream.  The ammonia nitrification is carried out by aerating the
effluent  sufficiently  to  assure  the  conversion  of  all  the
nitrogen in the raw effluent to the nitrite-nitrate  forms  prior
to the aerobic denitrification step.

The  denitrification  step,  converting  nitrates to nitrogen and
nitrogen oxides, takes place in the absence  of  oxygen.    It  is
thought   to  proceed  too  slowly  without  the  addition  of  a
biodegradable carbon source such as sugar, ethyl alcohol,   acetic
acid,  or methanol.  Methanol is the least expensive and performs
satisfactorily.  Investigators working on this process have found
that a 30-percent excess  of  methanol  over  the  stoichiometric
amount is required.23,29

In  current  waste treatment practice using anaerobic and aerobic
lagoons, ammonia nitrogen that disappears in the  aerobic   system


                              103

-------
  Partial
Secondary
Treatment
 Effluent
\

Aeration
System




Anaerobic
Pond



Aeration
Cell



                         Carbon
                         Source,
                       e.g. Methanol
                Figure  20.   Nitrification/Denitrification
                                                 Partial
                                                Tertiary
                                              ^ Treated
                                                Effluent
      Nitrification:


            NH3  + 02
            TO2  +  HsO     (Nitrosotnonas)
            2N0
           2NO-
                               (Nitrobacter)
      Denitrification (using methanol  as  carbon source)
6H
              +
6N03
                           5CH3OH
5C0
13
            Small amounts of N20 and  NO  are also formed
                                            (Facultative heterotrophs)

-------
does  not  show  up  to  a large extent as nitrites and nitrates.
Ammonia stripping is not likely to  account  for  the  loss.   It
appears  that  denitrification  must actually be occurring in the
bottom reaches of the aerobic lagoons, where anaerobic conditions
are probably approached  (see data presented in Section X).

Presuming  total  conversion  of  the  ammonia  to  nitrites   or
nitrates,  there  will  be virtually no nitrogen remaining in the
effluent from the denitrification process.  Nitrogen removal  can
be  maintained  at  about  90 percent over the range of operating
temperatures; the rate increases with temperature to  an  optimum
value  at  approximately  30°C  for  most  aerobic waste systems.
Temperature increases beyond 30° result in a decrease in the rate
for the mesophilic organisms.28

The waste water is routed to a second  aeration  basin  following
denitrificaticn,  where  the  nitrogen  and  nitrogen  oxide  are
readily stripped from the waste stream as gases.  The sludge from
each stage is settled and  recycled  to  preserve  the  organisms
required for each step in the process.


Development Status

The   specific  nitrification-denitrification  process  described
herein has only been carried out at the  bench-  and  pilot-^scale
levels.   Gulp  and  Gulp23  suggest  that  the  "practicality of
consistently maintaining the necessary biological  reactions  and
the  related  economics  must  be  demonstrated  on a plant-scale
before the potential of the process can be accurately evaluated."
A pilot model of a three-stage  system  using  this  process  was
reportedly  developed at the Cincinnati Water Research Laboratory
of the EPA and is being built at Manassas, Virginia.30  This work
is also reported to be experimental.  Thus, it can  be  concluded
that this process is, as of now, unproven.  However, as mentioned
above,  observations  of  treatment  lagoons for rendering plants
indicates that the suggested reactions are occurring  in  present
systems.   Also,  Halvorson31  reported that Pasveer is achieving
success in denitrification by carefully controlling the  reaction
rate  in an oxidation ditch, so that dissolved oxygen levels drop
to near zero just before the  water  is  reaerated  by  the  next
rotor.

Problems and Reliability

In  view  of the experimental status of this process, it would be
premature to speculate on the reliability or  problems  incumbent
in a fullscale operation.  It would appear that there would be no
exceptional maintenance or residual pollution problems associated
with  this  process  in  view of the mechanisms suggested for its
implementation at this time.
                              105

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                        Ammonia Stripping
Ammonia stripping  is  a  modification   of   the  simple  aeration
process  for  removing  gases  in water.  Figure 21.   Following pH
adjustment, the waste water is fed  to a  packed tower and  allowed
to  flow  down through the tower with a  countercurrent air stream
introduced at the bottom of the tower flowing upward to strip the
ammonia.  Ammonia-nitrogen removals of  up to 98 percent and  down
to  concentrations  of  less  than   1   mg/1 have been achieved in
experimental ammonia stripping towers.23

Technical Description

The pH of the waste water from a secondary   treatment  system is
adjusted  to  between  11  and 12 and the waste water is fed to a
packed or cooling tower  type  of   stripping  tower.   As  pH is
shifted  to  above  9, the ammonia  is present as a soluble gas in
the waste water  stream,  rather  than   as   the  ammonium  ion.2'
Ammonia-nitrogen   removal   of  90 percent  was  achieved  with
countercurrent air flows between 1.8 and  2.2  cubic  meters per
liter   (250  and  300 cubic feet per gallon)  of waste water in an
experimental tower with hydraulic loadings  between  100  and 125
liters  per minute per square meter (2.5 and 3 gallons per minute
per square foot).  The best performance was achieved with an air
rate  of  5.9  cubic meters per liter  (800  cubic feet per gallon)
and a hydraulic loading of 33 liters per minute per square  meter
 (0.8  gallons  per  minute  per  square  foot)   and  the  ammonia
concentration was reduced to less than  one  part per million at 98
percent removal.  The high percentage removal of ammonia-nitrogen
is  achieved  only  at  a  substantial   cost  in  terms  of  air
requirements and stripping tower cross-sectional area.23


Development Status

The  ammonia  stripping  process is a well-established industrial
practice  in  the  petroleum   refinery   industry.     The   only
significant difference between the  petroleum refinery application
and that on rendering waste would be the comparatively small size
of stripping tower required for the rendering plants, compared to
the  refinery.   The  air  stripping of  ammonia  from secondary
effluent is  reported  primarily  on an  experimental  basis in
equipment  that is 1.8 meters  (6 feet)  in diameter with a packing
depth of up to 7.3 meters  (24 feet). Two  large-scale  installa-
tions  of  ammonia  stripping  of   lime-treated  waste  water are
reported  at  South  Tahoe,  California,  and   Windhoek,   South
Africa.°6,23   The South Tahoe ammonia  stripper was rated at 14.2
M liters per day  (3.75 MGD) and was essentially constructed as   a
cooling tower structure, rather than as a cylindrical steel tower
which might be used in smaller sized plants.

Thus,  although  there is no reported use of ammonia stripping on
rendering plant waste, the technology   is  well  established  and
implementation,  when  standards   require  it,  would be possible
without great difficulty.  Problems and Reliability
                             106

-------
The reliability of this process has been established by petroleum
refinery use cf the process over many years.  Although the source
of  the  ammonia  may  be  different  and  there  may  be   other
contaminants  in  the  water  stream,  this should not affect the
established reliability of this process.  The experience of other
users of the process will  have  identified  potential  problems,
and,  presumably, the solutions for these problems will have been
found.  The maintenance requirements would be only those normally
associated with the mechanical equipment involved in pumping  the
waste  water to the top of the tower where the feed is introduced
to the tower, and in maintaining the air blowers.  The tower fill
would undoubtedly be designed for the kind of service involved in
treating a  waste  water  stream  that  has  some  potential  for
fouling.
                     Spray/Flood Irrigation

A  no-discharge  level  for  rendering  waste water can be and is
being achieved by  the  use  of  spray  or  flood  irrigation  of
relatively  flat  land, surrounded by dikes to prevent runoff.  A
cover crop of grass or other  vegetation  is  maintained  on  the
land.  Specific plant situations may preclude the installation of
irrigation   systems;  however,  where  they  are  feasible,  the
economics can be very favorable and serious consideration  should
be given to them.

Technical Description

Wastes  are  disposed  of in spray or flood irrigation systems by
distribution through piping and  spray  nozzles  over  relatively
flat terrain or by the pumping and disposal through the ridge and
furrow irrigation systems which allow a certain level of flooding
on  a given plot of land, Figure 22.  Pretreatment for removal of
solids is advisable to prevent plugging of the spray nozzles,  or
deposition  in  the  furrows  of  a  ridgeand-furrow  system,  or
collection of  solids  on  the  surface,  which  may  cause  odor
problems or clog the soil.  Therefore, the BOD5 will usually have
already  been reduced in preliminary treatment  (primary plus some
degree of secondary treatment)  upstream  from  the  distribution
system.

In  flood  irrigation, the waste loading in the effluent would be
limited by the waste loading tolerance  of  the  particular  crop
being  grown  on  the  land,  or  it  may  be limited by the soil
conditions or potential for vermin or odor problems.

Waste water distributed in either manner percolates  through  the
soil  and  the organic matter in the waste undergoes a biological
degradation.  The liquid in the waste stream is either stored  in
the  soil or leached to a groundwater aquifer and discharged into
the groundwater.  Approximately ten percent  of  the  waste  flow
will   be   lost   by  evapotranspiration   (the  loss  caused  by
evaporation to the atmosphere through the leaves of plants).28

Spray runoff irrigation is an  alternative  technique  which  has
been  tested  on  the  waste  from  a  small meat packer32  and on
                              107

-------
cannery waste.28  With this technique, about 50   percent  of  the
waste  water  applied  to  the  soil  is  allowed to  run off as a
discharge rather than no dischare, as discussed here.   The runoff
or discharge from this type of irrigation  system  is  of  higher
quality  than  the  waste  water as applied, with BOD5  removal of
about 80 percent;  total  organic  carbon  and  ammonia  nitrogen
system is of higher quality than the waste water  as applied,  with
BOD5  removal  of  about  80  percent;  total  organic  carbon and
ammonia nitrogen are about 85 percent reduced, and  phosphorus is
about 65 percent reduced.32

The  following  factors  will  affect the ability of  a  particular
land area to absorb waste water:  1) character of  the   soil,  2)
stratification  of  the soil profile, 3) depth to groundwater, 4)
initial moisture content, and 5) terrain and groundcover.28

The potentially greatest concern in the use of  irrigation  as a
disposal  system  is  the  total  dissolved  solids   content  and
particularly the salt content of the waste water.   A  maximum salt
content of 0.15 percent  is  suggested  by  Eckenfelder.28   Some
plants or some locations may require treatment in an  ion exchange
system   upstream  from  the  irrigation  system  to  reduce  the
dissolved solids and the salt content to  acceptable  levels  for
continuing  application of the waste water on land.   However,  the
average plant should have no problem with salt, since the average
salt content of rendering waste waters is about a factor  of  six
less than the limit of 0.15 percent suggested by  Eckenfelder.

An  application  rate  of up to 330 liters per minute per hectare
 (35  gallons  per  minute  per  acre)  has  been    suggested  in
determining the quantity of land required for various waste water
flows.   This  amounts  to almost 5 cm  (2 inches) of  moisture per
day, and is relatively low in comparison with  application  rates
reported  by  Eckenfelder for various spray irrigation  systems.28
However, solids vary widely in their percolation  properties  and
experimental  irrigation  of a small area is recommended before a
complete system is built.  In this report land requirements  were
based  on  2.5  cm   (one  inch) applied per operating day for six
months  of  the  year  with  lagoon   storage   for  six-months'
accumulation of waste water.

Waste  water application rates currently used by  rendering plants
with spray irrigation systems are less than 4.0 cm   (1.6  inches)
water  per  two  weeks  for  a  six-month  irrigation period.  If
rendering plant waste waters were being used as the sole nitrogen
source for corn growth, the waste waters would probably  have to
contain   250   to   500   mg/1  nitrogen.   For  lower  nitrogen
concentrations, the  corn  crop  would  probably  be  damaged by
flooding  or  by  heavy  overwatering  before  the   corn received
sufficient nitrogen from the waste waters.  This  is based on  the
assumptions  that one bushel of ccrn requires 454 gm  (1 pound) of
nitrogen; that the yield is 120 bushels of  corn  per  acre,  and
that the corn would require from 25 to 75 cm  (10  to 30  inches) of
water  per  season.3*   This  water rate amounts  to 3.1 to 9.5 cm
 (1.2 to 3.7 inches) of water per two  weeks,  over   a  four-month
                             108

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Secondary
Treatment
 Effluent
    PH
Adjustment
                                                              Treated
                                                             Effluent
                    Figure 21.  Ammonia Stripping
  Primary,
Secondary
    or
  Partial
 Tertiary
 Treatment
  Effluent
X.

Holding
Basin
N^
^"^
Pumping
System
\
^~
Application
Site
                                                           V
                                                        Grass or
                                                        Hay Crop
               Figure  22.  Spray/Flood  Irrigation System
        Partial
       Tertiary
      Treatment
       Effluent
                                                     Tertiary
                                                 ->  Treated
                                                     Effluent
                             Ion
                          Exchange
                          Column(s)
                Backwash  8
                 Regenerant
                  System
                       Figure 23.  Ion Exchange
                             109

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season-    Thus^   treated  waste  water  from rendering  is a  small
enough volume so it can  be  used  as  a  supplementary nutrient
source  for  corn rather than a sole resource of nutrients.  Data
were not discovered for any cases in which  waste  water  treated
only by primary systems was used for irrigation.

The  economic  benefit  from spray irrigation is estimated on the
basis of raising two crops of grass or  hay  per  season  with  a
yield of 13.4 metric tons of dry matter per hectare  (six tons per
acre)  and  values  at  $22  per metric ton  ($20 per ton).   These
figures are reportedly conservative in terms  of  the   number  of
crops and the price to be expected from a grass or hay  crop.  The
supply  and demand sensitivity as well as transportation problems
for moving the crop to a consumer all mitigate against  any  more
optimistic estimate of economic benefits.33

Cold  climate  uses  of  spray  irrigation may be subject to more
constraints  ad  have  greater  land  requirements  than   plants
operating  in more temperate climates.  However, a meat packer in
Illinois reportedly operated an irrigation  system  successfully.
Eckenfelder  also  reports that the wastes have been successfully
disposed  of  by  spray  irrigation  from  a  number    of    other
industries.28  Rendering plants located in cold climates or  short
growing  areas  should  consider  two crops for spray irrigation.
One  could be a secondary crop such as corn and the other a   grass
crop.   The  grass  crop  could  tolerate heavier volume loadings
without runoff and erosion, and also would extend the   irrigation
season  from  early  spring  to  possibly  late  November.   Corn,
although a more  valuable  crop,  tolerates  irrigation in  cold
climate areas only during the summer months.

North Star found in its survey of the rendering industry that the
plants  located  in  the  arid regions of the Southwest were most
inclinded to use spray or flood irrigation systems.


Problems and Reliability

The  long-term reliability of spray cr flood irrigation  systems is
a  function of the ability of the soil to continue to  accept the
waste,  and  thus  reliability remains somewhat open to question.
Problems in maintenance are  primarily  in  the  control  of the
dissolved  solids  level  and salinity content of the waste  water
stream and  also  in  climatic  limitations  that  may  exist  or
develop.  Many soils may be improved by spray irrigation.

                          Ion Exchange

Ion  exchange,  as  a  tertiary  waste  treatment,  is  used as  a
deionization process in which specific ionic species are  removed
from  the  waste  water stream, Figure 23.  Ion exchange would be
used to remove salt  (sodium chloride) from waters.  Ion exchange
resin  systems  have  been  developed  to  remove  specific  ionic
species, to achieve maximum  regeneration  operating  efficiency,
and  to achieve a desired effluent quality.  In treating rendering


                              110

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waste, the desired effluent quality would be a waste water with a
salt  concentration  of less than 300 mg/1.  Ion exchange systems
are available that will remove up to  90 percent of the salt in  a
water stream.*6  They can also be used to remove nitrogen.


Technical Description

The deionization of water by means of ion exchange resin involves
the  use  of both cation and anion exchange resins in sequence or
in combination to remove an electrolyte such as salt.


The normal practice in deionization of water has been to make the
first pass through a strong acid column, cation  exchange  resin,
in  which  the  first  reaction  shown  in  the equations occurs.
Effluent from the first column is passed to a  second  column  of
anion exchange resin to remove the acid formed in the first step,
as  indicated  in  the  second reaction.  As indicated in the two
reactions, the sodium chloride ions have been  removed  as  ionic
species.   A  great  variety  of  ion  exchange  resins have been
developed over the years for specific deionization objectives for
various water quality conditions.

Waste  water  treatment  with  ion  exchange  resins   has   been
investigated  and  attempted  for  over 40 years; however, recent
process developments in the treatment of secondary effluent  have
been  particularly  successful in achieving high quality effluent
at reasonable capital and operating costs.  One such process is a
modification of the Rohm and  Haas,   Desal  process.16   In  this
process  a  weak  base  ion  exchange  resin  is converted to the
bicarbonate form and the secondary effluent  is  treated  by  the
resin  to  remove  the  inorganic  salts.   After  this step, the
process includes a flocculation/aeration and  precipitation  step
to  remove organic matter; however, this should be unnecessary if
a sand filter or comparable system is used upstream  of  the. ion
exchange  unit.   The effluent from the first ion exchange column
is further treated by a weak cation resin  to  reduce  the  final
dissolved  salt content to approximately 5 mg/1.  The anion resin
in this process is regenerated  with  aqueous  ammonia,  and  the
cation  resin  with an aqueous sulfuric acid.  The resins did not
appear to be susceptible to fouling by the organic  constitutents
of the secondary effluent used in this experiment.

Other  types  of  resins  are  available for ammonia, nitrate, or
phosphate removal as well as  for  color  bodies,  COD  and  fine
suspended  matter.   Removal  of  these various constitutents can
range  from  75  percent  to  97  percent,   depending   on   the
constituent.2 3

The cycle time on the ion exchange unit will be a function of the
time  required  to  block  or  to  take up the ion exchange sites
available in the resin contained in the system.  Blockage  occurs
when   the   resin  is  fouled  by  suspended  matter  and  other
contaminants.  The ion exchange system is ideally located at  the


                              111

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end of the waste water processing scheme, thus having the highest
quality effluent available as a feedwater.

To  achieve  a  recycleable water quality, it may be assumed that
less than 500 mg/1 of total dissolved solids  would  have  to  be
achieved.   Of  the  total dissolved solids, 300 mg/1 of salt are
assumed  to  be  acceptable.   To  achieve  this  final  effluent
quality,  some  portion or all of the waste water stream would be
subjected to ion exchange treatment.  The residual pollution will
be that resulting from regeneration of the ion exchange bed.  The
resin systems, as indicated earlier, can be tailored to  specific
ion  removal  and  efficient  use  of regneration chemicals, thus
minimizing liquid wastes from the regeneration step.

Development Status

Ion exchange as a unit operation is well established and commonly
used in a wide range of applications in water treatment and water
deionization.  Water softening  for  boiler  feed  treatment  and
domestic  and  commercial use is probably the most widespread use
of ion exchange in water treatment.  Deionization of water by ion
exchange is used to remove carbon dioxide; metal  salts  such  as
chlorides,   sulfates,  nitrates,  and  phosphates;  silica;  and
alkalinity.  Specific resin applications such as in  waste  water
treatment  have not been widespread up to the present time, since
there has not  been  a  need  for  such  a  level  of  treatment.
However, process development and experimental work have shown the
capability  of  ion exchange systems to achieve the water quality
that may be required for irrigation and closed-loop water recycle
systems.

Part of the  economic  success  of  an  ion  exchange  system  in
treating  rendering  plant  waste  will probably depend on a high
quality  effluent being available as a feed material.  This again,
can be provided by an upstream  treatment  system  such  as  sand
filtration  to  remove  a  maximum of the particularly bothersome
suspended organic material.  However, the effect of a low quality
feed would be primarily economic because of shorter cycle  times,
rather  than  a reduction in the overall effectiveness of the ion
exchange system in removing a  specific  ionic  species  such  as
salt.
Problems and Reliability

The application of the technology in waste treatment has not been
tested  and therefore the reliability in that application has yet
to be established.  The problems  associated  with  ion  exchange
operations  would  primarily center on the quality of the feed to
the ion exchange system and its effect on the  cycle  time.   The
operation  and control of the deionization-regeneration cycle can
be  totally  automated,  which  would  seem  to  be  the  desired
approach.   Regeneration solution is used periodically to restore
the ion exchange resin to its original state for  continued  use.
This  solution must be disposed of following its use and that may

                                112

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require special handling  or  treatment.   The  relatively  small
quantity  of  regenerant  solution  will  facilitate  its  proper
disposal by users of this system.
                                113

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                          SECTION VIII

            COST, ENERGY AND NONWATER QUALITY ASPECTS


                             SUMMARY

The waste water from rendering plants is amenable to treatment in
secondary and tertiary waste treatment  systems  to  achieve  low
levels  of  pollutants in the final effluent.  In-plant controls,
product  recovery  operations,  and   strict   water   management
practices  can be highly effective in reducing the waste load and
waste water flow from any rendering plant.  The water  management
practices  will  reduce  the  requisite  size  of  secondary  and
tertiary treatment systems  and  improve  their  waste  reduction
effectiveness s.

For   purposes  of  estimating  treatment  costs,  the  rendering
industry can be  divided  into  small,  medium,  and  large  size
plants.   The  plant  size is based on the weight of raw material
processed per day.  This division of the industry does not  imply
the  need  to  categorize  the  industry  according  to size; the
primary categorization criterion—raw waste load—does  not  vary
with  size.   Total investment costs and unit operating costs for
waste treatment, on the other hand, will vary  with  plant  size.
Costs   that  represent  the  industry  situation  could  not  be
determined on the basis of one "typical"  plant  size,  with  the
wide  range  of production and waste water flow for plants in the
industry.  Therefore, the three rendering plant  sizes  that  are
relatively closely grouped in production and waste water flow are
used  to  describe  the  waste treatment economics for the entire
rendering industry and for plants within the industry.

Waste water treatment investment cost is primarily a function  of
waste  water  flow  rate.   Cost per unit of production for waste
treatment will vary with total investment cost and the production
rate.  Therefore, the rendering  industry  treatment  costs  have
been estimated on the basis of "typical" plants for each size.  A
"typical"   plant   is  a  hypothetical  plant  with  an  average
production rate and the indicated waste water flow rate as  shown
in Table 13A.

The  average BOD5 raw waste load is the same for each plant size,
as indicated  by  the  single  industry  category,  described  in
Section IV.

The additional capital expenditures required of a "typical" plant
in  each size group to upgrade or install a waste water treatment
system to achieve the  indicated  performance  are  indicated  in
Table  14.   Table  15  shows  comparative  costs  as  related to
expanding the hydraulic capacity of existing treatment facilities
if barometric condenser  recirculation  is  not  practiced.   The
estimated  total investment cost to the industry is also reported
for the proposed 1977 and 1983 limitations.
                               115

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                                      Table  13A.   Profile of Typical Plants by Size

Small
Medium
Large
Rendering Plant Size
Ran
kg /day
<45,000
45,000 - 113,500
>113,500
ges
Ib/day
<100,000
100,000 - 250,000
>250,000
Average Raw
Materials Processed
kg /day
16,800
76,300
240,600
Ib/day
37,000
168,000
530,000
Average Waste
Water Flow Rate
liters /day
20,000
91,000
288,000
gal /day
5,300
24,000
76,000
cr>

-------
The  estimate  of  the  cost  of  achieving  the  proposed   1977
limitations  is based on the following assumptions, which reflect
the data collected on the  industry  in  the  North  Star  survey
questionnaire:

     o    80 percent of the small plants with treatment systems
          will need to install pumps and piping to recirculate
          waste water to the barometric condensers; or expand
          lagoon capacity if recirculation of barometric
          condenser water is not practiced.

     o    50 percent of all plants with treatment systems will
          need to add an anaerobic lagcon or the equivalent.

     o    50 percent of all plants with treatment systems will
          need to install chlorination.

The  rendering  industry waste treatment practices are assumed to
be as reflected in questionnaire data for 49  plants.   The  data
reveals  a 50-50 split between municipal discharge and those that
treat or control their own waste waters.   The  latter  group  is
itself  split about 50-50.  Thus, of the approximately 450 plants
encompassed by this study,  225  are  municipal  discharges,   112
achieve  no  discharge  of pollutants, and 113 treat waste waters
and discharge to streams.  A further discussion of the  relevance
of this distribution is presented below under the heading, "Waste
Treatment  Systems"  between  no  discharge  and  treatment  with
discharge.

The 1983 limitations will require the following additions to  the
existing  treatment  systems,  over  and  above the additions for
1977:

     o    90 percent of all plants with treatment systems must
          add sand filters, or the equivalent;

     o    50 percent of all plants with treatment systems will
          have to make capital improvements in their primary
          treatment facilities;

     o    12 percent of all plants with treatment systems will
          have to eliminate direct blood drainage to the sewer
          and recover it in their product streams;

     o    20 percent of all plants with treatment systems will
          have to install ammonia stripping equipment or
          nitrification-denitrification systems.

The costs for irrigation and for ponding are included in Table 14
to indicate the economic advantages  of  both  approaches.   Both
techniques  produce  no  discharge, which is the ultimate goal of
the legislation, and free a  plant  from  waste  water  discharge
regulations.    The   no-discharge   options   are   particularly
advantageous to the small renderers.
                                117

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The investment  costs  for  new  point  sources  of  waste  water
effluent are cost estimates of treatment systems presently  in  use
in  the industry based on the average flow for the plant  size,  as
indicated in Table 14.

The basis of the cost  estimates  for  a  plant  to  achieve   the
proposed  limitations  involved  various  additions  to   existing
facilities, thus the investment cost for a given plant could vary
from a minimum to a maximum cost.   A  "most  likely"  investment
cost  was  computed  for each plant size based on the cost  of  the
combination  of  treatment-system  additions  with  the   highest
probability of occurrence.  The most likely and maximum costs  are
presented  in  Table  16.   All  operating and total annual costs
include the "most likely" investment cost rather than the minimum
or maximum cost.

Tables 15,  ISA,  and  15B  are  also  presented  to  provide   an
indication  of the approximate cost of waste treatment for  plants
with waste water  volume  per  unit  of  raw  material  processed
equivalent  to the average batch process renderer without the  use
of water conservation or recirculation systems  (3300  liters/1000
kgs or 400 gal/1000 Ib RM).  Investment costs would be higher  for
such  a plant.  Operating costs would increase in comparison with
the low waste water volume plant by 18 to 75 percent depending on
plant size and annual costs would increase by 12 to 125   percent.
The  medium  size plants would experience the largest increase in
the per unit annual cost for 1977 of 0.030/lb RM and small  plants
would incur the largest increase  in  annual  cost  for   1983   of
0.28iZ/lb  RM,  again  in comparison with the plant using  only  143
gal/1000 Ib RM.

The additions to plant operating cost and total annual  cost,   in
total  dollars and in dollars per unit of raw material processed,
for the indicated type or level of  waste  treatment  performance
are listed in Table 17 and 18.  The additional costs for  the 1977
limitations  include  the  payroll  and  burden  (at 50 percent of
payroll) for the equivalent of one-half man.  This  assumed cost
of  manpower for the treatment system accounts for between  70  and
82 percent of the annual operating cost and  between  45  and   60
percent  of  the  total annual cost.  This allocation of  manpower
cost would be highly discretionary within each  rendering  plant.
Therefore, the reported operating and total annual costs  are very
conservative  estimates  of  expected  real plant experience,  the
estimates probably are higher than what will actually occur.

The maximum annual costs per unit weight of raw material  occur in
the small  plants.   The  1977  limitations  would  add   0.350/kg
(0.160/lb)   to  the  annual  operating  cost  of an average small
plant, and the 1983 limitations would  add  0.840/kg   (0.380/lb).
In  comparison  with  the  operating margin of a rendering  plant,
these are significant additions to their costs.   The   costs   for
irrigation  or ponding are at least a factor of six less  than  the
cost  for  other  treatment  methods  for  small   plants.     The
additional  cost  for the medium or large rendering plant to meet


                                118

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Table 14.  Likely Capital Expenditures by Plant Size to Limitations Shown
           with Condenser Recirculation as Needed


Small Plant
Medium Plant
Large Plant
Total
Rendering
Industry
1977
Limitation
(?)
26,500
27,000
52,000

2,100,000
1983
Limitation
($)
53,000
85,000
119,000

8,900,000
New Source
Standard
($)
38,000
78,000
133,000

__
Irrigation
System Only**
($)
5,000
14,000
37,000

^^
Percolator &
Evaporation Pond
($)
14,000
32,000
62,000

— _

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the 1983 limitations is no greater  than
matter which treatment system is used.
0.2fZ/kg  (0.10/lb) ,  no
The  total  rendering industry spent  approximately $30 million in
1972 on new capital expenditures.   This  estimate is  based  on  a
projection  of the capital expenditures  reported for 1958 through
1967 in the 1967 Census of  Manufactures.4    The  total  industry
waste treatment expenditures reported in Tables  14 and 15 of $2.1
to  $4.2  million  for  1977 limitations and  $8.9 million for the
1983 limitations, amounting to about  10  percent  and 30 percent of
the $30 million  estimate,  respectively.   The   waste  treatment
expenditures  can  be programmed over a  number of years, thus the
requisite investment  appears  reasonable  and  achievable.    The
small  rendering  plant  is  put  in  the most difficult financial
position, however, this can be minimized by the  use of irrigation
or ponding.

The electrical energy consumption in  waste  water treatment by the
rendering industry amounts  to  less   than  2 percent  of  their
current  total use of electrical energy,  and  less than 0.1 of one
percent of their total  (heat plus electrical)  energy consumption.
Thus,  in  absolute  terms  and  comparatively  speaking,   waste
treatment energy use is of little consequence.

With  the  implementation  of  these   standards, land becomes the
primary waste sink instead of air and water.   The  waste  to  be
disposed  on  land  from  rendering plants  can improve soils with
nutrients and soil conditioners contained  in the  waste.   Odor
problems can be avoided or eliminated in all  treatment systems.
            Table 15.  Estimated Waste Treatment Investment  Costs for
                     Renderers with High Waste Water Volume
                     (3300 liters/1000 kgs RM or 400 Gals/1000 Ibs KM)
Plant
Size
Small
Medium
Large
1977
Limitations
20,700
47,600
94,000
1983
Limitations
135,000
208,000
293,000
Irrigation
System, Only
13,100
34,000
90,000
                                 120

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Table 15A.  Total Annual and Operating Costs for a Rendering
           Plant with High Waste Water Volume to Meet the
           Indicated Performance, $/Year
Plant
Size.

Small


Medium


Large


Cost
Annual

Operating
Annual

Operating
Annual

Operating
1977
Limitations
16,600

12,400
24,400

14,900
36,800

18,000
1983
Limitations
61,100

30,000
87,700

36,600
121,900

44,500
Irrigation
System, Only
6,200

4,000
9,800

4,200
16,300

2,000
   Table 15B.  Annual and Operating Costs  Per Unit  Weight  of
              Raw Material for a Rendering Plant with High
              Waste Water Volume to Meet  Indicated Performance
Plant
Size
Small
Medium
Large
Cost
Annual
Operating
Annual
Operating
Annual
Operating
1977 Limitations
C/kg
0.39
0.30
0.13
0.08
0.06
0.03
C/lb
0.18
0.13
0.06
0.035
0.03
0.014
1983 Limitations
C/kg
1.45
0.71
0.46
0.19
0.20
0.07
C/lb
0.66
0.32
0.21
0.09
0.09
0.03
                            121

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Table 16.   Comparison  of  Most  Likely  and Maximum  Investment, with  Condenser
           Recirculation,  By Plant  Size
Performance

1977 Limitations
1983 Limitations
Small Plant
Most
Likely
Cost
($)
26,500
53,000
Maximum
Cost
($)
26,500
100,000
Medium Plant
Most
Likely
Cost
($)
27,000
85,000
Maximum
Cost
($)
42,000
160,000
Large Plant
Most
Likely
Cost
($)
52,000
119,000
Maximum
Cost
($)
52,000
221,000
              Table 18.  Annual And Operating Costs Per Unit Weight
                         of Raw Material for a Rendering Plant to
                         Meet Indicated Performance


Plant

Small

Medium

Large


Cost
Annual
Cost
Operating
Cost
Annual
Cost
Operating
Cost
Annual
Cost
Operating
Cost

1977
Limitation
C/kg
0.35
0.24
0.07
0.04
0.03
0.02

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Table 17.   Total Annual and Operating Costs  for  a  Rendering
           Plant to Meet the Indicated Performance,  $/Year
Plant
Size

Small


Medium


Large


Cost
Annual
Cost

Operating
Cost
Annual
Cost

Operating
Cost
Annual
Cost

Operating
Cost
1977
Limitation
16,500

11,900
16,200

12,200
21,600

14,000
1983
Limitation
40,300

25,100
48,200

27,300
62,600

31,300
New Source
Standard
20,500

14 , 700
30,600

18,800
44,100

24,100
Irrigation
System
1,500

500
3,500

700
7,600

230

Ponding
2,700

750
6,100

1,600
11,800

3,100

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                         "TYPICAL" PLANT

The  waste  treatment  systems applicable to waste water from the
rendering industry can be used effectively by all plants  in  the
industry.  Irrigation or ponding with no discharge is  most widely
used  by  small  plants,  and  is  usually  the  most   attractive
treatment option for  small  plants.   A  hypothetical  "typical"
plant  was  determined  for  each  plant  size   as   the basis for
estimating investment cost and total annual and  Operating  costs
for the application of each waste treatment system for each plant
size.   The  costs  were  estimated,  and  in  addition,  effluent
reduction, energy requirements, and nonwater quality  aspects  of
the treatment systems were determined.

The  waste  treatment  systems  are  applied  on the basis of the
"typical" plants described in Table 19 for each  plant  size.


               Table 19.  "Typical" Plant Parameters for each  Plant Size
Plant Parameter
Average Raw Material
Processed, kg/day,
(Ibs/day)
Standard Deviation
of Average R. M.
Processed
kg/day, (Ibs/day)
Total Waste Water
Volume, liters/day
(gals/day)
Waste Water Vol-
ume per unit of R. M.
Processed
liter /1000 kgs ,
(gals/1000 Ib RM)
Average Value of Plant Parameter by Plant Size
Small
16,800
(37,000)
9,100
(20,000)
20,000
(5,300)
1,191
(143)
Medium
76,300
(168,000)
26,300
(58,000)
91,000
(24,000)
1,191
(143)
Large
240,000
(530,000)
74,900
(165,000)
288,000
(76,000)
1,191
(143)
The small rendering plant generally has a  lower  production  limit
of  about  4500  to 6800 kg  (10,000 to 15,000  Ib)  of raw material
processed per day.  This estimate is based on  the  industry sample
data and involves the use of one batch cooker  operating  on  two
batches per day.  This level of operation  would  be at the low end
of  economic viability.  The North Star sample included one plant
that processed about 3600 kg  (8000  Ib)  per   day   of  only  dead
                                124

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animals.   This type of raw material enabled the plant to operate
at that production level, however, it was unique in the sample.

The  waste  water  volume  is  primarily  based  on  the  average
normalized  water volume for all of the continuous process plants
in the sample, 1191 liters/kkg RM  (143 gal./lOOO  Ib  RM).   This
means  that  all  plants  with  barometric  condensers  and waste
treatment will have to recirculate condenser water from the waste
treatment system and thus avoid this large consumption  of  fresh
water  and  reduce the total waste water volume.  Costs have been
included for such revision of barometric condenser  water  supply
systems, as indicated previously.  At the same time, however, the
"typical"  batch  plant  was  also  analyzed  regarding costs for
treatment without condenser recirculation  for  both  the  purely
(lagoon)  treatment  mode  and  the option of irrigation, in each
case with respect to the 1977 limitations.
                     WASTE TREATMENT SYSTEMS

The  waste  treatment  systems  included  in   this   report   as
appropriate for use on rendering plant waste water streams can be
used, subject to specific operating constraints or limitations as
described later, by most plants in the industry.  The use of some
treatment  systems  may  be  precluded  by  physical  or economic
impracticability for some plants.

The waste treatment systems, their use, and the minimum  effluent
reduction associated with each are listed in Table 20.

The  dissolved  air  flotation system can be used upstream of any
secondary treatment system.  The use of chemicals should increase
the quantity of grease removed from the waste water  stream,  but
may   reduce   the  value  of  the  grease  because  of  chemical
contaminants.

The secondary treatment  systems  are  generally  land  intensive
because of the long retention time required in natural biological
processes.   Mechanically  assisted systems have reduced the land
requirements but increased the energy  consumption  and  cost  of
equipment  to achieve comparable levels of waste reduction.  Some
of the tertiary systems are interchangeable.  Any of them can  be
used  at  the  end  of  any of the secondary treatment systems to
achieve a required effluent quality.  Chlorination is included if
a disinfection treatment is required.  A final clarifier has been
included in costing out all  biological  treatment  systems  that
generate a substantial sludge volume; e.g., extended aeration and
activated  sludge.   The clarifier is needed to reduce the solids
content of the final effluent.

The most feasible system to achieve no discharge at this time  is
flood  or  spray  irrigation  or  ponding.  Closing the loop to a
total water recycle or reuse system is technically feasible,  but
far  too  costly  for  consideration.  The irrigation option does
require   large   plots   of   accessible    land—roughly    2.0


                              125

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                 Table 20    Waste Treatment Systems, Their
                            Use and Effectiveness
 Treatment System
                                Use
                                                   Effluent Reduction
Dissolved air
flotation (DAF)
DAF with pH control
and flocculants
added

Anaerobic + aerobic
lagoons

Anaerobic contact
process

Activated sludge

Extended aeration

Anaerobic lagoons +
rotating biological
contactor

Chlorination


Sand filter


Microstrainer


Ammonia stripping

Chemical
precipitation


Spray irrigation

Flood irrigation

Ponding and
evaporation

Nitrification and
Denitrification
Primary treatment or
by-product recovery
Primary treatment or
by-product recovery
Secondary treatment


Secondary treatment


Secondary treatment

Secondary treatment

Secondary treatment
Finish and
disinfection

Tertiary treatment &
secondary treatment

Tertiary treatment
Tertiary treatment

Tertiary treatment



No discharge

No discharge

No discharge


Tertiary treatment
Grease, 60% removal,
  to 100 to 200 mg/1
BOD5, 30% removal
SS, 30% removal

Grease, 95-99% removal
BOD5, 90% removal
SS, 98% removal

BODS, 95% removal
BOD5, 90-95% removal


BOD5, 90-95% removal

BOD5, 95% removal

BOD5, 90-95% removal
BOD5, to 5-10 mg/1
SS, to 3-8 mg/1

BOD5, to 10-20 mg/1
SS, to 10-15 mg/1

90-95% removal

Phosphorus, 85-95%
  removal, to 0.5 mg/1
  or less

Total

Total

Total
N,  85%  removal
                             126

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hectares/mi11ion  liters   (0.2  acres/thousand  gallons) of waste
water per day and limited  concentrations  of  dissolved  solids.
More  detailed  descriptions  of  each  treatment  system and its
effectiveness are presented in Section VII—Control and Treatment
Technology.

Of the 49 plants responding to  the  study  questionnaire,  about
one-half  reported  having either their own waste water treatment
system or no discharge; the others  indicated  discharging  their
waste  to  a  municipal treatment system.  Twelve plants reported
on-site  secondary  treatment  with  lagoon  systems   or   other
combinations  of  secondary  treatment  processes.  Twelve plants
also reported treatment systems with no discharge.   Chlorination
is used by five plants, according to the data.


The  North Star sample of rendering plants provided the following
waste water treatment information and  industry  sources  believe
these data conform to overall industry practice:

                    Discharge to    Secondary Treatment    No
                  Municipal System    With Discharge    Discharge

Small Plants               7                 48

Medium Plants              7                 53

Large Plants               9                 31

TOTALS                    23                12             12
                   TREATMENT AND CONTROL COSTS

                     In-Plant Control Costs

The  purchase and installation cost of in-plant control equipment
is  primarily  a  function  of  each  specific  plant  situation.
Building layout and construction design will largely dictate what
can  be  done,  how, and at what cost in regard to in-plant waste
control techniques.  In-plant control equipment  costs  were  not
included   in   the   total  investment  cost  estimates.   Rough
approximations of the range of costs for  the  in-plant  controls
requiring  capital  equipment are  listed in Table 21.  These cost
ranges are based  somewhat  on  plant  size  variation,  but  are
primarily  based  on  the expected cost that might be incurred by
any rendering plant, depending on  the plant layout, age, type  of
construction, etc.

                  Investment Costs Assumptions

The  waste  treatment system costs are based on the average plant
production capacity and waste water flow listed previously for   a
                               127

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                             Table  21.   Estimates  of  In-Plant Control Costs
                  Plant  Area
ro
oo
                  Raw Materials  Storage
                  Cookers
                 Air Scrubbing
                 Hide Curing
                 Materials Recovery
Item
Steam sparge and screen
for high blood contain-
ing waters.

By-pass controls on
vapor lines from
cookers

Recycle system for
scrubber water

Pipe curing waste
waters to cookers

Flow equalization tank
Equipment Cost Range
  $10,000-$15,000



  $100-$300 per cooker



  $10,000-$20,000


  $1,000-$3,000


  $2,000-$5,000

-------
"typical,"  but  hypothetical,  plant  of  each size.  Investment
costs  for  specific  waste  treatment  systems   are   primarily
dependent on the waste water volume.


The  total  waste  water flow for each plant size will vary up to
100 percent or more of the average  total  flow  for  that  size.
This  variability  coupled  with that in cost estimating suggests
that the waste treatment investment costs for  a  specific  plant
may be only within an accuracy of + 50 to 100 percent.

The  investment  cost  data  were collected from data included on
questionnaires from rendering plants,  the  literature,  personal
plant  visits,  equipment manufacturers, engineering contractors,
and  consultants.   The  costs  are  "ball-park"-type  estimates,
implying  an accuracy of + 20 to 25 percent.  Rarely is it minus.
All costs  are  reported  in  August  1971  dollars.   Percentage
factors  were  added  to  the treatment system equipment cost for
design and engineering  (10 percent)   and  for  contingencies  and
omissions  (15  percent).   Land costs were estimated to be $2470
per hectare  ($1000 per acre) .

The irrigation system costs are based on application and  storage
assumptions  to  take  into consideration geographic and climatic
variables throughout  the  country.   These  assumptions  are  as
follows:

     o    Application rate is one inch of waste water applied
          per operating day during six months per year.

     o    Storage capacity for six months accumulation of
          waste water in a lagoon 1.2 m (4 feet)  deep plus
          land for roads, dikes, etc.

     o    Irrigation equipment includes pumps, piping and
          distribution system, dikes to prevent all runoff
          at a reference cost of $70,000 for 21 hectares
          (52 acres) .

The chlorine costs are based on chlorinating the waste water to 8
mg/1.   The  assumed  cost of 180 per kg  (80 per Ib) for chlorine
results in a cost of 0.10 per 1000 liters  (0.40 per 10CO gal.) of
waste water chlorinated.

In addition to the  variation  in  plant  water  flows  and  BOD5
loadings  and  the  inherent  inaccuracy  in cost estimating, one
additional factor further limits  the  probability  of  obtaining
precise  cost  estimates  for  specific  waste treatment systems.
This factor was reported by a  number  of  informed  sources  who
indicated  that  municipal  treatment  systems will cost up to 50
percent  more  than  comparable  industrial  installations.   The
literature  usually  makes  no  distinction between municipal and
industrial installation in reporting investment costs.
                               129

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                                         Figure  24.   Waste  Treatment Cost Effectiveness
CO
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i/iJ.vJ —
99 —
\— QR
g 98 —
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CJ
CC
LU
Q_ Qf- _M
— yo
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o
o 90 -
D
Q
LU
CC
Q 80 -
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O
LU 70 —
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00
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^>
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LU
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§ 30 -
cc
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< 20 —

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91,000 I/day .
(24,000 GPD)7










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1 SECONDARY
! TREATMENT
, 	 1
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(76,000 GPD)








I nrtinAAi-ix/ -rn i- A TRfli-M-r


60 80 100 120 140 160 180 200 220 240 260 280 300

-------
Cost effectiveness data are presented in Figure  24,  as  investment
cost required to achieve the  indicated  BOD5  removal  with  the
typical  lagoon  waste  treatment   system  at two levels of waste
water flow.  The low flow is the  average  for   the  medium   size
rendering  plant  and  the high flow is the average  for the large
plants.  The raw waste reduction is based on the construction  of
waste  treatment  systems  with  the  incremental waste reduction
achieved  by  adding  treatment  components  to  the system    as
indicated  below  (a  catch  basin  is  assumed  to  be  standard
practice, and the raw waste is that  discharged  from  the  catch
basin).
 Treatment Component                      Total Raw Waste  Reduction,  %

Catch Basin                                        0

+ Improved Primary Treatment                      15

+ Anaerobic and Aerobic Lagoons                   95

+ Aerated Lagoon                                  98

+ Sand Filter                                     99+


                     Annual Cost Assumptions

The   components   of   total   annual  cost  are  capital  cost,
depreciation, operating and maintenance  costs,  and energy  and
power  costs.  The cost of capital  is estimated  to be ten percent
of the investment cost for the rendering industry—the  same as  in
the meat packing  industry.   This  cost  should be  a  weighted
average  of  the  cost of equity and of debt financing  throughout
the  industry.   Neither  individual   companies  nor   industry
associations  have  a known figure  for this cost.  Presuming  that
target and  realized  return-on-investment   (ROI)  or   return-on-
assets   (ROA)  figures  incorporate some estimate of capital  cost
plus an acceptable  profit  or  return,  industry  and  corporate
reports  were used as a guide in selecting the ten percent figure
for the meat packing industry.  One sample of companies  reported
earnings  at  7.1  percent  of  total assets for 1971 ;35 a recent
business periodical reported earnings at 10.1 percent of invested
capital,36 and meat packing  industry  sources   report  corporate
target  ROI and ROA figures at 12 to 15 percent  for  new ventures.
The ten percent figure  is  probably  high,  and thus  tends  to
contribute  to  a  high estimate of total annual cost.  Operating
cost includes all the components  of  total  annual  cost  except
capital cost and depreciation.

The  depreciation  component  of  annual  cost was estimated  on a
straight-line tasis over the following lifetimes, with  no  salvage
value:

          Land costs — not depreciated

          Land intensive treatment  systems; e.g., lagoons  --  25 years


                               131

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          All other treatment systems — 10 years.

The operating and maintenance costs for the 1983  system  include
the  cost  of  one  man-year  at  $4.20/hour  plus 50 percent for
burden, supervision, etc.  One-half man-year  was  used   for  the
annual  cost for the 1977 limitations plus the 50 percent burden,
etc.  General and maintenance  supplies,  taxes,  insurance,  and
miscellaneous  operating costs were estimated as 5 percent of the
total investment cost per year.  Specific chemical-use costs were
added when such materials were consumed in  the  waste  treatment
system.   By-product  income,  relative  to  waste treatment, was
credited only in the irrigation  system  for  13,400  kg  of  dry
matter   (hay  or grass)  per hectare at $22/100 kg (6 tons/acre at
$20/ton) and two crops per year.37


                       ENERGY REQUIREMENTS

The electrical energy consumption by the rendering  industry—SIC
2077, including marine fats and oils—was reported for 1967  (then
under   SIC  2094)  to be 362 million KWH and total heat and power
energy  consumption at the equivalent of 8108 KWH.*  The rendering
industry  consumes  relatively  small  quantities  of  electrical
energy  but large quantities of fuel.  The waste treatment systems
require  power  primarily for pumping and aeration.  The  aeration
horsepower is a function of the waste load and that  for  pumping
depends on waste water flow rate.

Total   power  consumption  to  achieve  the  1977  limitations is
estimated to  be  7  million  KWH  per  year  for  the  rendering
industry.   This  amounts to about 2 percent of electrical energy
consumption, and roughly 0.1  percent  of  the  total   (heat  and
electrical) energy consumption of the industry reported for 1967.
The  same  approximate  percentage  would  apply to current power
consumption.   The  additional  power  needed  to  achieve   1983
limitations  amounts  to  about  4  percent  and  0.2  percent of
electrical and the  total  energy,  respectively,  and  does  not
appear  to  raise  serious power supply or cost questions for the
industry.  However, widespread use of chlorine as a  disinfectant
may  pose some energy problems in the future, or, conversely, the
future  supply of  chlorine  may  be  seriously  affected  by  the
developing energy situation.

Waste   treatment  systems  impose  no significant addition to the
thermal energy requirements of plants.  Waste water can be reused
in cooling and condensing service.   These  heated  waste waters
improve  the  effectiveness  of  anaerobic  ponds, which  are best
maintained at about 90°F.  Improved thermal efficiencies  are also
achieved within a plant  when  waste  water  is  reused   in  this
manner.

Waste   water treatment costs and effectiveness can be improved by
the use of energy and power conservation practices and techniques
in plant operations.  Reduced water  use  therefore  reduces  the


                              132

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pumping costs and heating costs, the last of which can be further
reduced by water reuse as suggested above.
          NONWATER POLLUTION BY WASTE TREATMENT SYSTEMS

                          Solid Wastes

Solid   wastes  are  the  most  significant  nonwater  pollutants
associated with the waste treatment  systems  applicable  to  the
rendering  industry.   Screening  devices  of  various design and
operating principles are used primarily  for  removal  of  large-
scale  solids from waste water.  These solids have economic value
as inedible rendering raw material and can  be  returned  to  the
feed end of a plant.

The  organic  and  inorganic  solids  material separated from the
waste water stream,  including  chemicals  added  to  aid  solids
separation,  is  called  sludge.  Typically, it contains 95 to 98
percent water before dewatering  or  drying.   Both  primary  and
secondary  treatment  systems generate some quantities of sludge;
the quantity will vary by the  type  of  system  and  is  roughly
estimated as shown below.
Tr ea tm en t_ Sy_s tern

Dissolved air flotation

Anaerobic lagoon

Aerobic and aerated lagoons


Activated sludge

Extended aeration

Anaerobic contact process

Rotating biological contactor
Sludge Volume as Percent of
Raw Wastewater TVolume

Up to 10%

Sludge accumulation in
these lagoons is usually
not sufficient to require
removal.

10 - 15%

5 - 10%

Approximately 2%

Unknown
The  raw  sludge can be concentrated, digested, dewatered, dried,
incinerated, land-filled on-site, or  spread  in  sludge  holding
ponds.   The sludge from any of the treatment systems, except air
flotation with polyelectrolyte chemicals  added,   is  amenable  to
any of these sludge handling processes.

The sludge from air flotation with chemicals has  proven difficult
to  dewater  in  a  couple  of  plants.   A dewatered sludge  is an
acceptable land fill material.  Sludge  from  secondary  treatment
systems  is  normally  ponded  by  plants on   their  own land or
dewatered or digested sufficiently for  hauling  and depositing  in
public land fills.  The final dried sludge material can be safely
                               133

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used as an effective soil builder.  Prevention of water runoff is
a  critical  factor in plant-site sludge holding ponds.  Costs of
typical sludge handling techniques for each  secondary  treatment
system  generating  sufficient  quantities  of  sludge to require
handling equipment are included in the costs for these systems.


                          Air Pollution

Odors are the only significant air pollution  problem  associated
with  waste  treatment  in  the  rendering  industry.  Malodorous
conditions usually occur in anaerobic waste  treatment  processes
or  localized  anaerobic  environments  within  aerobic  systems.
However, it is generally agreed that  anaerobic  ponds  will  not
create  serious  odor  problems  unless  the  process water has a
sulfate content; then it most assuredly will.  Sulfate waters are
definitely a localized condition varying even from well  to  well
within  a  specific  plant.  In a northern climate, the change in
weather in the spring may be accompanied by a period of increased
odor problems.

The anaerobic pond odor potential is  somewhat  unpredictable  as
evidenced  by  a few plants without sulfate waters that have odor
problems.  In these cases a cover and collector  of  the  off-gas
from the pond controls odor.  The off-gas is burned in a flare.

The  other potential odor generators in waste water treatment are
leaking tanks and process equipment items used in  the  anaerobic
contact  process  that  normally generate methane.  However, with
the process confined to a  specific  piece  of  equipment  it  is
relatively  easy  to  confine and control odors by collecting and
burning the off-gases.  The high heating  value  of  these  gases
makes  it  worthwhile and a frequent practice to recover the heat
for use in the waste treatment process.

Odors have been generated by some air flotation systems which are
normally housed in a building, thus localizing, but  intensifying
the  problem.  Minimizing the unnecessary holdup of any skimmings
or grease-containing solids has been suggested as a remedy.

Odors can best be controlled by elimination at the source, rather
than resorting to  treatment  for  odor  control,  which  remains
largely unproven at this time.
                              Noise

The  only  material  increase  in  noise within a rendering plant
caused by waste treatment is that caused by the  installation  of
an  air  flotation  system  or  aerated lagoons with air blowers.
Large pumps and an air compressor are part of  an  air  flotation
system.   The  industry frequently houses such a system in a low-
cost building; thus, the substantial noise generated  by  an   air
flotation   system   is   confined   and   perhaps  amplified  by
installation practices.  All air compressors,  air  blowers,   and


                              134

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large  pumps in use on intensively aerated treatment systems, and
other treatment systems as well,   may  produce  noise  levels  in
excess  of   the  Occupational  Safety  and  Health Administration
standards.   The industry must consider these standards in solving
its waste pollution problems.
                               135

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                           SECTION IX

            EFFLUENT REDUCTION ATTAINABLE THROUGH THE
               APPLICATION OF THE BEST PRACTICABLE
                  CONTROL TECHNOLOGY CURRENTLY
           AVAILABLE—EFFLUENT LIMITATIONS GUIDELINES
                          INTRODUCTION

The effluent limitations which must be achieved July 1, 1977, are
to specify the degree of effluent  reduction  attainable  through
the  application  of  the  Best  Practicable  Control  Technology
Currently Available.   This technology 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 was  not  based  upon  a  broad
range  of  plants  within the independent rendering industry, but
based upon performance levels achieved by exemplary plants.

Consideration was also given to:

     o     The total cost of application of technology in relation
          to the effluent reduction benefits to be achieved from
          such application;

     o     The size and age of equipment and facilities involved;

     o     The processes employed;

     o     The engineering aspects of the application of various
          types of control techniques;

     o     Process changes;

     o     Nonwater quality environmental impact (including energy
          requirements).


Also, Best Practicable  Control  Technology  Currently  Available
emphasizes  treatment  facilities  at  the end of a manufacturing
process, but includes the control technologies within the process
itself  when the latter  are  considered  to  be  normal  practice
within  an industry.

A further consideration is the degree of economic and engineering
reliability  which  must  be established for the technology to be
"currently available."  As a result  of  demonstration  projects,
pilot  plants  and general use, there must exist a high degree of
confidence in the engineering and economic practicability of  the
technology  at  the time of start of construction of installation
of the  control facilities.
                                137

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    EFFLUENT REDUCTION ATTAINABLE THROUGH THE APPLICATION OF
      BEST POLLUTION CONTROL TECHNOLOGY CURRENTLY AVAILABLE

Based on the informatior contained in Sections III   through VIII
of chis report, a determination has been made that the  quality  of
effluent attainable through the application of the Best Pollution
Control  Technology Currently Available is as listed in Table 22.
Of the ten plants with materials recovery systems  and   secondary
treatment  systems  for which information on effluent quality was
available^ two are meeting these standards.  An  additional four
of the plants come close to meeting these standards.

Hide  curing  at  an  independent  rendering  plant   requires   an
adjustment in the limitation for BOD5, and  SS   (Table   23).    An
adjustment  does  not  become  significant,  however,   unless the
number of hides handled is quite large.

For example, an average size plant, as found in  this  study,   is
one  handling  94,000  kg  (206,000 pounds) RM  (raw materials) per
day, and also curing 100 hides,  and  would  have  the   following
adjustment factors  (AF):


     AF  (BOD5)  =  8_x_100   = 0.0085 kg/kkg RM  (lb/1000 Ib RM)
                   94,000

     AF  (TSS)   =  ll_x_100  = 0.012 kg/kkg RM  (lb/1000  Ib  RM)
                   94,000

From  Table 22 and the above correction, the effluent limitations
for this pollutant would be 0.15 + 0.0085, and 0.17   +   0.012   or
0.182  kg/kkg  (lb/1000  Ib)  RM  (a 5 and 7 percent  increase) for
BOD5 and SS, respectively.  An  adjustment  for  grease  was not
included  because  there  was  no correlation between the raw and
final waste loads for grease.  For instance, for the six  plants
meeting  the  grease  limit   (of  the nine plants for which final
effluent data on grease were  available)  only  two   of  the six
plants had raw grease loads less than the industry average  (which
was  0.72 kg/kkg RM) .  The other four plants had raw grease loads
that were 1.5, 1.6, 4.3, and 7.6 times greater than   the  average
value  of  0.72.    Yet,  five  of the six plants had final  grease
concentrations that '-'ere within a range of  2  to  23  mg/1;  the
sixth  had  a  final  grer.ss  concentration  of 54 mg/1.   It thus
appears that the treatment system used, can reduce grease  in the
final  effluent  to  relatively  low  values,  independent  of the
grease in the raw waste.
                              138

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           Table 22.  Recommended Effluent Limitation
                      Guidelines for July 1,  1977
    Effluent Parameter
     Effluent Limitation
    BOD 5

    Suspended solids  (SS)

    Grease

    Fecal coliform
     0.15 kg/kkg RM  (lb/1000 Ib KM)

     0.2Q kg/kkg RM  (lb/1000 Ib RM)

     0.10 kg/kkg RM  (lb/1000 Ib RM)

     400 counts/100 ml
           Table 23.  Effluent Limitations Adjustment
                      Factors for Hide Curing
Effluent Parameter   (kg/kkg  RM or  lb/1000 Ib RM)
BOD5
8.0 x (no. of hides) _ j-7.6 x  (no. of hides)
     ( kg of RM)      ~       (Ib  of RM)
            ...   ,-_,    11 x  (no. of hides)      24.2  x  (no.  of hides)
Suspended solxds  (SS)  =      ( kg of RM)       =       (Ib of  RM)
                                 139

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            IDENTIFICATION OF BEST POLLUTION CONTROL
                 TECENOLOGY CURRENTLY AVAILABLE

Best Pollution Control Technology  Currently  Available  for  the
independent   rendering   industry   involves   biological  waste
treatment following a materials recovery process for  grease  and
solids.    To  assure that treatment will successfully achieve the
limits specified, certain in-plant practices should be followed:

     1.    Materials recovery system—catch basins, skimming tanks,
          air flotation, etc.—should provide for at least a 30-
          minute detention time of the waste water.

     2.    Reuse of treated waters for operating barometric leg
          condensers rather than fresh water.  This minimizes
          net waste water volume; for a given size of treatment
          system, it permits a longer effective residence time.

     3.    Removal of grease and solids from the materials recovery
          system on a continuous or regularly scheduled basis to
          permit optimum performance.

     4.    Provide adequate cooling of condensables to ensure that
          the temperature of the waste water in the materials
          recovery system does not exceed 52°C  (125°F).  This allows
          for improved grease recovery.

     5.    Scrape, shovel, or pick up by other means as much as
          possible of material spills before washing the floors with
          hot water.

     6.    Minimize drainage from materials receiving areas.  This
          may require the pumping of the liquid drainage back onto
          the raw materials as it is conveyed from the area.

     7.    Repair equipment leaks as soon as possible.

     8.    Provide for regularly scheduled equipment maintenance
          programs.

     9.    Avoid over-filling cookers.

    10.    Provide and maintain traps in the cooking vapor lines
          to prevent overflow to the condensers.  This is particularly
          important when the cookers are used to hydrolyze materials.

    11.    Contain materials when equipment failure occurs and while
          equipment is being repaired.

    12.    Steam sparge and screen liquid drainage from high water-
          and blood-containing materials, such as poultry feathers
          on which blood has been dumped.

    13.    Plug sewers and provide supervision when unloading or
          transferring raw blood.  Blood has a BOD5 of between


                                140

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              Table  24.  Raw and  Final  Effluent  Information  for Ten Rendering Plants
Plant
Number —'
1
2
3
4
5
6
7
8
9
10
Flow,
1000 liters
(1000 gal.)
454 (120
57 U5)
132 (35)
45 (12)
3028 (800)
102 (27)
2120 (560)
106 (28)
625 (165)
19 (5)
RM/Day ,
kkg
(1000 Ib)
170 (374)
9 (20)
86 (190)
68 (150)
390 (860)
32 (70)
300 (660)
75 (165)
265 (583)
26 (57)
BOD Load,
kg /kkg RM*
Raw
1.77
0.79
16.22
2.66
4.51
1.28
5.86
6.93
3.64
3.50
Final
0.06
0.04
0.16
0.06
0.18
0.27
0.86
0.09
0.34
0.07
SS Load,
kg /kkg RM*
Raw
2.81
6.96
6.69
1.45
2.42
0.65
3.50
2.77
0.80
—
Final
0.08
0.21
0.006
0.09
0.42
0.30
4.4
0.14
0.20
—
Grease Load,
kg /kkg RM*
Raw
0.04
1.050
5.45
1.070
0.920
—
1.340
3.120
1.150
0.63
Final
0.006
0.10
0.035
0.150
0.220
—
0.300
0.028
0.038
0.040
Final Fecal
Coliform**
(Counts/100 ml)
—
3,600
70,000
50
99 (Cl)
—
270,000
99
100 (Cl)
4,700
 *kg/kkg RM = lb/1000 Ib RM
**(C1)  indicates chlorination of final effluent.
  17 For plant number 3, high  raw wastes  due  to malfunction in grease/
    solids recovery system, and  final  SS value not  used due to
    atypical final settling.   Plant  number  7 was  not used  to derive
    limits due to apparent severe malfunction in  normally  satisfactory
    treatment facility.

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          150,000 and 200,000 mg/1.8                               J

    14.    Provide by-pass controls for controlling pressure reduc- :*
          tion rates of cookers after hydrolysis.  Cooker agitation ''
          may have to be stopped also, during cooker pressure bleed-'!
          down to prevent, or minimize materials carry-over.

    15.    Minimize water use for scrubbers by recycling and reuse.

    16.    Evaporate tank water to stick and use as tankage in dry  :i
          inedible rendering.                                       '

    17.    Do not add uncontaminated water to the contaminated water l
          to be treated.                                            ;

    18.    By-pass the materials recovery process with low grease-
          bearing waste waters.

The above practices can readily produce a raw  waste  load  below
that  cited as average in Section V.  With an average waste load,
use of  the  following  secondary  biological  treatment  systems   i
should  produce  an  effluent that meets the recommended effluent
limitations:

     1.   Anaerobic lagoon + aerobic  (shallow)  lagoons

     2.   Activated sludge + aerobic  (shallow)  lagoons

     3.   Aerated lagoons -t- aerobic  (shallow) lagoons.

Plants with a higher-than-average raw waste load or an  undersize
treatment   system   may   require  a  solids  removal  stage  or
chlorination as the  final  treatment  process.   Furthermore,  a
plant  located in a cold climate area may need sufficient holding
capacity in the aerobic lagoons because it cannot  discharge  for
periods of three to six months.

         RATIONALE FOR THE SELECTION OF BEST PRACTICABLE
             CONTROL TECHNOLOGY CURRENTLY AVAILABLE

The   rationale  used  in  developing  the  effluent  limitations
presented in Table 24 was based upon the actual  performances  of
ten  plants  having  what was considered to be complete secondary
treatment and for which sufficient information was available.   A
complete  secondary  treatment  system would include any properly
sized system mentioned in the preceding paragraph.


    Size, Age, Processes Employed, and Location of Facilities

The ten plants used for developing the effluent limitations cover
operations using different processes, equipment,  raw  materials,
and are of different size, age, and location of facilities.   Data
presented  in Section IV showed that these  factors did not  have  a
distinct  influence  on  the  raw  waste    characteristics    from


                              142

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independent  rendering  plants.   Furthermore, the final effluent
data from these ten plants reveal that the raw waste loads can be
readily  reduced  by  secondary  treatment  to  a  similar  level
regardless  of in-plant operations, raw materials used, and size,
age, and location of facilities.


                        Data Presentation

Table 24 presents the data for the ten plants.  Included in Table
24 are the plant size  (kkg or 1000 Ib RM/day), effluent  flow,raw
and  final  waste  loads  for  BOD5,  SS,  and  grease, and fecal
coliform counts in the final treated effluent.  Data for four  of
the  plants  represent  information  obtained  as a result of our
field sarrpling  survey;  data  for  the  other  six  plants  were
obtained  primarily  from questionnaire information and of these,
data for three plants were verified by the results of  the  field
survey.   Data  for plant number 7 were included, although it was
evident from visiting the plant and the results  shown  that  the
treatment  system at this plant was not functioning properly; the
effluent data were not used in determining the  effluent  limits.
Similarly,  the test results for SS for plant number 3 were found
to be inconsistent and were not used for calculating the effluent
limits.

The BOD5 effluent limitation of 0.15 kg/kgg RM is  basically  the
average  value  of the BOD5 data for all but  plant number 7.  The
data of Table 24 show that five of the  ten   plants  easily  meet
this limitation, while plants 3 and 5 come very close.  It should
be  noted  that  the  raw  BOD5  waste  loads for the five plants
meeting the effluent range from 0.79 to 6.93  kg BOD5/kkg  (lb/1000
Ib) RM and that the raw value for  plant  3,  whose  final  value
comes  close  to the limitation, is 16.2 kg/kkg RM.  In fact, the
average raw BOD5 value for the five plants meeting the limitation
is  3.13 kg BOD5/kkg  (lb/1000 Ib) RM.  The average of  all  plants
stuided was 2.15 kg BOD5/kkg RM; thus even plants with higher raw
BOD5  waste  loads than these industry averages can meet the BOD5
effluent limitation.

The suspended solids  (SS) effluent limitation value  of  0.17  kg
SS/kkg  RM  is  close to the average of all the values except for
that of plant 7.  The values for four plants  meet  the  effluent
limitation  for  suspended  solids.   Also, the raw SS values for
these four plants range from 1.45 to 6.69 kg  SS/kkg  (lb/1000  Ib)
RM  with an average value of 3.43 kg SS/kkg  (lb/1000 Ib RM).  The
overall average for all plants  studied is 1.13 kg SS/kkg  (lb/1000
Ib) RM.

The grease effluent limitation value of 0.10  kg grease/kkg  RM  is
very  nearly  the average grease value for the nine values  shown.
There are six plants that meet the  effluent  limitation.    These
six  plants  have  raw  waste values ranging  from 0.04 to  5.45  kg
grease/kkg  (lb/1000  Ib) RM, with an average value of 2.30.    This
average  raw  grease   value  for plants meeting the guidelines  is
                               143

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over three times as great as  the  average  for  grease  for  all
plants included in the study, which is 0.72.

Based  on  the  average raw waste load values for the ten plants,
with biological treatment systems, these plants must achieve  the
following  percent  reduction  to  meet  the effluent limitation:
96.8 for BOD5, 94.5 for SS, and 95.2 for  grease.   If,  however,
the  reductions are based on the average raw waste values for all
plants included in  the  study,  the  following  percentages  are
obtained:  93.0 for BOD5, 85.0 for suspended solids, and 86.1 for
grease.

Although  from four to seven of the plants used in developing the
effluent limitations meet at least  one  of  the  three  effluent
limitations,  only two plants are known to meet all three:  BOD5,
SS, and grease.  Another four plants meet the limitations for two
of the parameters and come very close to meeting the third.

The fecal coliform effluent limitation of 400 counts/100 ml is  a
typical  value  being used for a number of industries.  Data from
Table  24 show that four plants can meet this value, and that  two
of those are doing so without chlorination.  These two plants not
needing  chlorination  have  large anaerobic lagoons plus aerobic
lagoons for secondary treatment.  The fecal coliform counts given
in Table 24 were obtained using the  membrane  filter  procedure.
This   method  and  the multiple-tube technique which results in a
MPN  (most probable number)  value, yield comparable results.

The BOD5 and SS effluent limitation adjustment factors  for  hide
curing shown in Table 23 were developed using the data from Table
11  and  the  average  BOD5 and SS reduction required to meet the
limitations.  These reductions are 93 and 85 percent for BOD5 and
SS, respectively; the values produce adjustment factors of  0.008
kg   (0.0176  Ib)  BOD5/hide and 0.011 kg  (0.0242 Ib) SS/hide.  As
discussed earlier, no adjustment was developed for grease.

       Engineering Aspects of Control Technique Applications

The  specified  level  of  control   technology,   primary   plus
biological  treatment,  is  practicable  because  it is currently
being  practiced by plants representing  a  wide  range  of  plant
sizes  and  types.   However,  if additional treatment is needed,
such as sand beds or mixed media filter beds this  technology  is
practical  as  evidenced  by  its  use  by  other industries8 and
municipalities.


Process Changes

Significant in-plant changes will  not  be  needed  by  the  vast
majority  of  plants  to  meet  the  limitations specified.  Many
plants will  have  to  improve  plant  cleanup  and  housekeeping
practices,  both  responsive  to  good  plant management control.
This can  best  be  achieved  by  ir.iniirdzing  spills,  containing
materials  upon equipment breakdown, and using dry cleaning prior


                               144

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to washdown.  Some plants may find it necessary to pretreat truck
and raw materials drainage, blood water, and  tank  water  before
mixing  them  with  other  waste  waters  prior  to  entering the
materials  recovery  system.   Some  plants  may  also  find   it
necessary to use improved gravity separation systems, such as air
flotation with chemical precipitation.  Additional cooling of the
waste water before grease recovery may be required in some cases.
              Nonwater Quality Environmental Impact
   \
The  major  impact when the option of an activated sludge type of
system or, possibly,  chemical  precipitation  in  the  materials
recovery  system  is  used  to  achieve  the  limitations will be
disposal of the sludge.  Nearby land for sludge disposal  may  be
necessary; in some cases a sludge digester  (stabilizer) may offer
a  solution.   Properly  operated  activated  sludge-type systems
should permit well conditioned  sludge  to  be  placed  in  small
nearby soil plots for drying without great difficulty.

It   was  concluded  that  the  odor  emitted  periodically  from
anaerobic lagoons is not a major impact as it  can  be  with  the
meat  packing  industry.8  Also, there are no new kinds of impact
introduced by the application of the best current technology.
                                 145

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                            SECTION X

    EFFLUENT REDUCTION ATTAINABLE THROUGH THE APPLICATION OF
     THE BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE—
                 EFFLUENT LIMITATIONS GUIDELINES
                          INTRODUCTION

The effluent limitations which must be  achieved  no  later  than
July 1,  1983,  are not based on an average of the best performance
within  an industrial category, but are determined by identifying
the very best control and  treatment  technology  employed  by  a
specific   point   source   within  the  industrial  category  or
subcategory, or by one industry where it is readily  transferable
to   another.    A  specific  finding  must  be  made  as  to  the
availability of control measures and practices to  eliminate  the
discharge  of  pollutants,  taking  into account the cost of such
elimination.

Consideration was also given to:

     o    The age of the equipment and facilities involved;

     o    The process employed;

     o    The engineering aspects of the application of various
          types of control techniques;

     o    Process changes;

     o    The cost of achieving the effluent reduction resulting
          from application of the technology;

     o    Nonwater quality environmental impact  (including energy
          requirements) .

Also,   Best   Available   Technology   Economically   Achievable
emphasizes  in-process  controls as well as control or additional
treatment techniques  employed  at  the  end  of  the  production
process.

This  level  of  technology  considers  those plant processes  and
control technologies which, at the pilot-plant,   semi-works,   and
other  levels,  have demonstrated both technological performances
and economic  viability   at  a  level  sufficient  to  reasonably
justify  investing  in such facilities.  It is the highest  degree
of  control  technology   that  has  been   achieved  or   has   been
demonstrated  to  be   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 of this level of  control are intended to be the top-of-the-
line  of  current  technology,   subject to limitations  imposed by
economic and engineering  feasibility.  However,  there may be some
technical risk  with respect to performance and   with  respect  to


                               147

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certainty  of  costs.   Therefore,  some  industrially   sponsored
development work may be needed prior tc its application.


    EFFLUENT REDUCTION ATTAINABLE THROUGH APPLICATION OF THE
        BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE

Based on  the  information  contained  in  this  section and  in
Sections III through VII of this report, a determination has been
made   that  the  quality  of  effluent  attainable  through  the
application  of  the  Best  Available   Technology   Economically
Achievable  is  as listed in Table 25.  The technology to achieve
these goals is generally available, although it may not  have been
applied as yet to an independent rendering plant  or  on a  full
scale.

Hide  curing  at  an  independent  rendering  plant  requires  an
adjustment in the limitations for BOD5 and SS.  These adjustments
are  listed  in  Table  26.   An  adjustment  does   not  become
significant,  however,  unless  the  number of hides handled by a
plant is quite large.  For example,  an  average  size   plant  as
found  in  this study, is one handling 94,000 kg  (206,000 pounds)
raw material  (RM)  per day, and that also cures  100  hides  would
have the following adjustment factors  (AF):

     AF(BOD5)  =  3...6_x_100  = 0.0038 kg/kkg RM  (lb/1000 Ib RM)
                   94,000

     AF (TSS)   =  6.._2_x_100  = 0.0066 kg/kkg RM  (lb/1000 Ib RM)
                   94,000
The  effluent limitations for this plant would therefore  be  0.074
and 0.107 kg/kkg RM  (lb/1000 Ib RM) for BOD5 and SS, respectively
(a 5.7 and 7 percent increase).  An adjustment for grease was not
included because there was no correlation  between  the   raw and
final  grease  values.   For example, the six plants that had the
lowest final grease  loads  (which ranged between about  0.006 and
0.10  kg  grease/kkg  RM)  out of the nine plants for which  final
effluent data on grease were  available,  had  raw  grease   loads
ranging  from  0.04  to  5.450  kg/kgg   (lb/1000  Ib) RM, with an
average for the six  raw values of 1.91 kg/kkg   (lb/1000   Ib)  RM.
Also,  only  two of  the six plants had raw grease loads less than
the industry average  (which was 0.72); the other four plants had
raw  grease  loads   that  were  1.5,  1.6,  4.3 and 7.6 times the
average.  It thus appears that  the  treatment  system  used can
reduce  grease  in   the  final effluent to relatively low values,
independent of the raw grease load.

It should also be pointed out that an independent renderer should
consider land disposal, and hence no discharge, for 1983.    Where
suitable  land  is   available,  evaporation  or  irrigation  is an
option that not only is recommended from the discharge viewpoint,
but  also  will  usually  be  more  economical  than  the system


                               148

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            Table 25.   Recommended  Effluent  Limitation
                       Guidelines for July 1,  1983
     Effluent  Parameter
Effluent Limitation*
     BOD5

     Suspended solids (SS)

     Grease

     Ammonia as N

     Total phosphorus as P

     pH

     Fecal coliform
0.07 kg/kkg RM

0.10 kg/kkg RM

0.05 kg/kkg RM

0.02 kg/kkg RM

0.05 kg/kkg RM

6.0 - 9.0

400 counts/100 ml
*kg/kkg RM = lb/1000 lb RM
     Table  26.   Effluent  Limitation Adjustment Factors
                 for  Hide  Curing

Effluent Parameter
BOD5
Suspended Solids (SS)
Adjustment Factor
kg/kkg RM
3.6 x (no. of hides)
(kg of RM)
6.2 x (no. of hides)
(kg of RM)
lb/1000 lb RM
7.9 x (no. of hides)
( lb of RM)
13 . 6 x (no . of hides)
(lb of RM)
                          149

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otherwise required.  In fact, out of the 48 independent rendering
plants included in this study for which discharge information was
available,  24 did not discharge to a municipal treatment system,
and 12 of them had no discharge.


         IDENTIFICATION OF THE BEST AVAILABLE TECHNOLOGY
                     ECONOMICALLY ACHIEVABLE

The Best Available Technology  Economically  Achievable  includes
that   listed  under  the  Best  Practicable  Control  Technology
Currently Available  (Section IX) , and a sand filter or equivalent
following secondary treatment.   In  addition,  some  plants  may
require  improved  pretreatment,  such as dissolved air flotation
with  pH  control  and  chemical  flocculation,  and  an  ammonia
stripping or nitrification-denitrification sequence.

In-plant  controls  and  modifications  may  also  be required to
achieve the specified levels.  These include the following:

     1.   Materials recovery systems—catch basins, skimming tanks,
          air flotation, etc.—should provide for at least a 30-
          minute detention time of the waste water.

     2.   Reuse of treated waters for operating barometric leg
          condensers rather than fresh water.  This minimizes
          net waste water volumes; for a given size of treatment
          system it permits a longer effective residence time.

     3.   Removal of grease and solids from the materials recovery
          system on a continuous or regularly scheduled basis to
          permit optirruin performance.

     4.   Provide adequate cooling of condensables to ensure that
          the temperature of the waste water in the materials
          recovery system does not exceed 52°C (125°F).  A tempera-
          ture below 38°C  (100°F) is even better.  This allows for
          improved grease recovery and, incidentally, minimizes
          odor problems.

     5.   Scrape, shovel, or pick up by other means as much as
          possible of material spilled before washing the floors
          with hot water.

     6.   Minimize drainage from materials receiving areas.  This
          may require the pumping of the liquid drainage back onto
          the raw materials as it is conveyed from the area to the
          first processing step.

     7.   Repair equipment leaks as soon as possible.

     8.   Provide for regularly scheduled equipment maintenance
          programs.

     9.   Avoid over-filling cookers.

                                 150

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                       Table 27.  Raw and Final Effluent Information for Ten Rendering Plants

                                  Table 27A.  Flow, RM/Day,  Final Fecal Coliform,
                                              and BOD5,  SS,  and Grease Waste Loads
Plant
Number ^J
1
2
3
4
5
6
7
8
9
10
Flow
1000 liters
(1000 gal.)
454 C120)
57 (15)
132 (35)
45 (12)
3028 (800)
102 (27)
2120 (560)
106 (28)
625 (165)
19 (5)
RM/Day
kkg
(1000 Ib)
170 (374)
9 (20)
86 (190)
68 (150)
390 (860)
32 (70)
300 (660)
75 (165)
265 (583)
26 (57)
BOD5 Load,
kg /kkg KM*
Raw
1.77
0.79
16.22
2.66
4.51
1.28
5.86
6.93
3.64
3.50
Final
0.06
0.04
0.16
0.06
0.18
0.27
0.86
0.09
0.34
0.07
SS Load,
kg /kkg RM*
Raw
2.81
6.96
6.69
1.45
2.42
0.65
3.50
2.77
0.80
—
Final
0.08
0.21
0.006
0.09
0.42
0.30
4.4
0.14
0.20
—
Grease Load,
kg/kkg RM*
Raw
0.04
1.050
5.45
1.070
0.920
—
1.340
3.120
1.150
0.63
Final
0.006
0.10
0.035
0.150
0.220
—
0.300
0.028
0.038
0.040
Final Fecal
Coliform**
(Counts/100 ml)

3,600
70,000
50
99 (Cl)
—
270,000
99
100 (Cl)
4,700
en
      *kg/kkg RM = pounds/1000 pounds RM
     **(C1) indicates chlorination of final effluent.
          I/ For plant number 3,  high raw wastes due to malfunction in grease/
             solids recovery system, and final SS value not used due to
             atypical final settling.  Plant number 7 was not used to derive
             limits due to apparent severe malfunction in normally satisfactory
             treatment facility.

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                          Table  27.  Raw and Final Effluent Information for Ten Rendering Plants
                                     (Continued)
                                    Table 27B.  TKN, NH3, N02, N03 and TP Waste Loads
Plant
Number
1
2
3
4
5
6*
7
8
9
10
Total
Kjeldahl
Nitrogen
Load as N
kg/kkg RM
Raw
0.49
0.38
0.94
0.38
0.44
—
1.2
0.33
0.82
0.23
Final
0.03
0.02
0.27
0.034
0.30
—
1.92
0.35
0.32
0.08
Ammonia
Load as N
kg/kkg RM
Raw
0.26
0.17
0.08
0.19
0.30
—
0.66
0.14
0.29
0.18
Final
0.001
0.005
0.26
0.0086
0.16
—
0.53
0.11
0.11
0.044
Nitrite
Load as N
kg/kkg RM
Raw
0.04
0.0001
0.0003
0.00002
0.0004
—
0.00036
0.00007
0.00079
0.0013
Final
0.001
0.008
0.00015
0.00005
0.0002
—
0.00036
0.00009
0.0013
0.00004
Nitrate
Load as N
kg/kkg RM
Raw
0.06
0.0001
0.0014
0.0015
0.0001
—
0.012
0.0015
0.018
0.0075
Final
0.0004
0.001
0.0024
0.00068
0.0001
—
0.012
0.0018
0.0077
0.001
Total
Phosphorus
Load as P
kg/kkg RM
Raw
0.01
0.013
0.08
0.031
0.062
—
0.28
0.04
0.04
0,023
Final
0.029
0.001
0.046
0.014
0.08
—
0.26
0.029
0.024
0.013
en
         *Nutrient values  for  this
         Part A  of  this  table for
plant are missing because the plant was not sampled.  The values shown in
this plant were obtained from the questionnaire.

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   10.   Provide and maintain traps in the cooking vapor lines to
         prevent overflow to the condensers.  This is particularly
         important when the cookers are used to hydrolyze materials.

   11.   Contain materials when equipment failure occurs and while
         equipment is being repaired.

   12.   Steam sparge and screen liquid drainage from high water-
         and blood-containing materials such as poultry feathers
         on which blood has been dumped.

   13.   Plug sewers and provide supervision when unloading or
         transferring raw blood.  Blood has a BOD5 of between
         150,000 and 200,000 mg/1.8

   14.   Provide by-pass controls for controlling pressure reduc-
         tion rates of cookers after hydrolysis.  Cooker agitation
         may have to be stopped also, during cooker  pressure bleed-
         down to prevent or minimize material carry-over.

   15.   Minimize water use for scrubbers by recycling and reuse.

   16.   Evaporate tank water to "stick" and use as  tankage in
         dry inedible rendering.

   17.   Do not add uncontaminated water to the contaminated water
         to be treated.

   18.   By-pass the materials recovery process with low grease-
         bearing waste waters.

   19.   Provide for flow equalization  (constant flow with time)
         through the materials recovery system.

   20.   Eliminate hide curing waste waters by mixing small volumes
         with large volumes of raw materials being  fed to cookers.

If suitable  land  is  available,  land  disposal   is the  best
technology; it is no discharge.  However, secondary  treatment  may
still  be  required  before  disposal  of  waste  waters  to  soil,
although the degree of treatment need not be the   same   as  that
required to  meet the 1977  limitations  (Section IX). Any of  the
systems mentioned in  Section IX are suitable.

Currently a number of  independent rendering  plants  are  achieving
no discharge  via   land   irrigation,  ponding,  and discharge to
septic tanks  followed by  sub-soil drainage  (drain  fields  or  large
cesspools).  some  plants  use two of   the above technologies   to
achieve  no  discharge.   For example,  evaporation  and ponding  may
be used  for  disposal  of  wash  water   and  drainage  from  raw
materials  receiving  areas,  and   septic tanks followed by  drain
fields for disposal of condensables.   This  method  of disposal   of
condensables also helps to contain  the associated  odor problem.

                               153

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          RATIONALE FOR SELECTION OF THE BEST AVAILABLE
               TECHNOLOGY ECONOMICALLY ACHIEVABLE

The  rationale  used  in developing the 1983 effluent limitations
presented in Table 25 was based  upon  the  performances  of  ten
waste treatment systems and information contained in Sections III
through  VII.   The  ten  treatment systems were considered to be
complete secondary treatment systems.  In addition,  chlorination
was being used by two of the ten plants.


    Size, Age, Processes Employed, and Location of Facilities

The ten plants used for developing the effluent limitations cover
operations  using  different processes, equipment, raw materials,
and are of different sizes, ages, and  locations  of  facilities.
Data  presented  in  Section  IV showed that these factors do not
have a distinct influence on the raw waste  characteristics  from
independent rendering plants.

The final effluent data from these ten plants reveal that the raw
waste  loads  can be substantially reduced by secondary treatment
to  a  similar  level  regardless  of  in-plant  operations,  raw
materials  used,  and size, age, and location of facilities.  The
levels to which secondary treatment  can  reduce  the  raw  waste
loads  will  be  sufficient  to allow the effluent from secondary
treatment to meet  effluent  limitations  for  a  number  of  the
pollutants  for  1983; however, tertiary treatment will be needed
to ensure that others  will  consistently  meet  1983  standards.
Plants  located  in  cold  climates  may  need sufficient holding
capacity in the secondary treatment system  because  they  cannot
discharge  during  the  coldest months of the year.  This is true
not only for plants that discharge their treated waste waters  to
navigable streams, but also for plants that irrigate.

                        Data Presentation

Table 27 presents the data for the ten plants.  Included in Table
27A  are  the  plant size  (kkg or 1000 Ib RM/day), effluent flow,
raw and final waste loads for BOD5, SS,  and  grease,  and  fecal
coliform  counts  in  the  final  treated  effluent.   Table  27B
includes raw  and  final  waste  load  data  for  total  Kjeldahl
nitrogen  (TKN) ,  ammonia   (NH3) , nitrates  (NO3) , nitrites  (N02) ,
and total phosphorus  (TP) .  Data for four of the plants in  Table
27A  represent  information  obtained  as  a  result of our field
sampling survey; data  for  the  other  six  plants  listed  were
obtained  primarily from questionnaire information, and of these,
data for three plants were verified by the results of  the  field
survey.   The  data  included in Table 27B were all obtained from
the results of the field sairpling survey.  Data for plant  number
7  were included, although it was evident from visiting the plant
and from the results shown in the table that the treatment system
at this plant was not functioning properly.
                              154

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The BOD5 effluent limitation of 0.07 kg/kgg RM  (0.07  lb/1000  Ib
RM)  is  a  value  being met by four of the ten plants  (see Table
27A) .  TWO of the four plants meeting this limit have  raw  waste
BOD5  loads greater than the industry average of 2.15 kg BODS/kkg
RM.  Thus, it appears that a well  operated  and  properly  sized
secondary  treatment  system  can produce an effluent with a BOD5
load that will meet the 1983 limitation.  Using the average  flow
value  for  the  industry,  which  is  4977  liters/kkg  RM  (597
gal./lOOO Ib RM), the BOD5 effluent limit value of 0.07 kg/kkg RM
corresponds to a final effluent concentration of 4.4 mg/1.  A BOD5
concentration this low usually means that  the  majority  of  the
BOD5  remaining  is  contained in the suspended solids.  In fact,
this is supported  by  the  results  of  a  correlation  analysis
between final BOD5 and suspended solids waste loads that showed a
high correlation between the two—the correlation coefficient was
0.87   (a  coefficient  of  1  would  be  a  perfect correlation).
Consequently, to ensure that the final  effluent  will  meet  the
1983  BOD5 limit during all periods of discharge will require the
use of a sand filter or its equivalent to reduce the remaining SS
and thus the EOD5.

The suspended solids   (SS)  effluent  limitation  value  of  0.10
kg/kkg RM  (0.10 lb/1000 Ib RM) is currently being met by three of
the  nine  plants  with  secondary  treatment for which there are
data.  These three plants all have raw SS loads greater than  the
industry  average,  which is 1.13 kg/kkg RM, as shown in Table 6.
As mentioned in  the  above  paragraph,  a  sand  filter  or  its
equivalent  will  be required to remove SS and  hence to lower the
BOD5.  This should therefore permit all plants  to  meet  the  SS
limitation value.  The SS limit, using the average flow value for
the industry of 4977 1/kkg  (597 gal./lOOO Ib) RM corresponds to  a
final  concentration  for  SS of 20 mg/1.  This concentration was
also considered to be about the practical limit  for  SS  removal
via a  sand filter  (see Section VII).

The  grease  limit  of  0.05  kg/kkg  RM  (0.05  lb/1000  Ib RM) was
chosen because  five of nine plants for  which   grease   data  were
available  (see Table 27A) met this limit.  This limit  should not
be difficult to achieve via secondary treatment; four of the five
plants meeting  the  limit  had  raw  grease  loads  considerably
greater  than  the  industry  average  of  0.72 kg grease/kkg RM.
Incidentally, this limit corresponds to  a  concentration   of   10
mg/1 when the water use equals the industry average of  4977  1/kkg
RM (597 gal./lOOO Ib RM).


The  ammonia  limit of 0.02 kg NH3 as N/kkg RM  (0.02  lb/1000  Ib RM)
is   being  met  by  three   plants  that  are  showing  substantial
reduction  in Total Kjeldahl Nitrogen.  The  reason   for  this   is
that   the  TKN  value,  which is the  sum  of the organic  and ammonia
nitrogen,  is largely  caused by ammonia  in the final  effluent,   as
can  be   seen  in Table  27B.  Thus, the  same  steps  that are being
used to  reduce  the TKN value  will  also  help  to  reduce  the ammonia
value.  Of course, the  best   approach   to   this   problem  is   to
eliminate or reduce  the  sources,  one  of which is  blood.


                               155

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The  pH limits of from 6.0 to 9.0 are not expected to require any
special control since all plants for which there were  data  have
effluents with pH in this range.

The  fecal  coliform  effluent limitation of 400 counts/100 ml is
the same as for the 1977 limits.  Data from Table 27A  show  that
four  plants can meet this value, and that two of those are doing
so without chlorination.  The two plants not needing chlorination
have large anaerobic lagoons plus aerobic lagoons  for  secondary
treatment.   The  fecal  ccliform  counts given in Table 27A were
obtained using the membrane filter procedure.   This  method  and
the multiple-tube technique which results in a MPN  (most probable
number) value, yield comparable results.

      Engineering Aspects of Control Technique Applications

The   specified   level  cf  control  technology,  primary,  plus
secondary, plus tertiary  (which will  include  at  least  a  sand
filter  or  its  equivalent  if  it is needed), is practicable; a
number of plants without tertiary treatment are currently meeting
the limits for the  individual  waste  parameters  as  previously
mentioned.   In  fact,  one  plant is currently meeting all waste
parameter limits, and several others are  meeting  the  majority.
Tertiary  treatment is required, however, to permit all plants to
meet the limits  for  all  pollutants.   The  specified  tertiary
treatment  is  practicable  because it is currently being used by
other industries.  Plants located in cold climates will  have  to
have  sufficient  capacity  in the treatment systems because they
cannot discharge for periods of about three months.   This,  too,
should  be  no major engineering problem since a number of plants
in this industry as well as others are currently doing this.8


                         Process Changes

Most plants will have to make in-plant changes to meet  the  1983
limitations,   particularly   to   meet   the   TKN  and  ammonia
limitations.   This  will  involve  improved  plant  cleanup  and
housekeeping  practices, both responsive to good plant management
control.   This  will  include  minimizing   spills,   containing
materials  upon  equipment breakdown, using dry cleaning prior to
washdown, and additional cooling of the waste waters  before  the
materials  recovery  system.   Still,  some  plants  may  find it
necessary to control drainage  from  trucks  and  raw  materials,
blood waters, tank water, and hide-curing waste waters.  Specific
suggestions on controlling these sources of waste water were made
earlier  in this section.  Some plants may also find it necessary
to improve the materials recovery system or replace  it  with  an
improved   system   such   as   air   flotation   with   chemical
precipitation.

                     Nonwater Quality Impact

The major impact will occur when  the  land  disposal  option  is
chosen.   There  is a potential long-term effect on the soil from


                              156

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irrigation of rendering  plant waste water and on  ground  waters.
To  date,  impacts   have been generally obviated by careful water
application management   and  by  biological  treatment  prior  to
disposal.

Otherwise,  the  effects  will  essentially be those described in
Section  IX, where  it was concluded that no new kinds  of  impacts
would be introduced.
                                  157

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                           SECTION XI

                NEW SOURCE PERFORMANCE STANDARDS


                          INTRODUCTION

The effluent limitations that must be achieved by new sources are
termed   New   Source  Performance  Standards.   The  New  Source
Performance Standards apply to any source for which  construction
starts  after the publication of the proposed regulations for the
Standards.   The  Standards  are  determined  by  adding  to  the
consideration   underlying   the   identification   of  the  Best
Practicable Control Technology Currently Available, a  determina-
tion  of  what  higher  levels of pollution control are available
through the use of improved production processes and/or treatment
techniques.  Thus, in addition to considering the  best  in-plant
and  end-of-process  control  technology.  New Source Performance
Standards are based on an analysis of how the level  of  effluent
may  be  reduced  by  changing  the  production  process  itself.
Alternative processes, operating methods  cr  other  alternatives
are  considered.   However,  the end result of the analysis is to
identify effluent  standards  which  reflect  levels  of  control
achievable  through  the use of improved production processes  (as
well as control technology), rather than prescribing a particular
type of process or technology which must be employed.  A  further
determination  is  made  as  to  whether a standard permitting no
discharge of pollutants is practicable.

Consideration was also given to:

     o    Operating methods;

     o    Batch, as opposed to continuous, operations;

     c    Process employed;

     o    Plant size;

     o    Recovery of pollutants as by-products.


                  EFFLUENT REDUCTION ATTAINABLE
                         FOR NEW SOURCES

The effluent limitations for new sources are  the   same   as   those
for  the   Best  Practicable Control Technology Currently  Available
for the pollutants BOD5, SS,  grease,  and  fecal   coliform  (see
Section   IX).    In   addition  to  these  pollutant  parameters,  the
following additional limits on nutrients  are  required   for  new
sources:
                                159

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            Effluent Parameter

            Ammonia as N
  Effluent Limitation
kg/kkg (lb/1000 Ib) RM

          0.17
These  limitations  are  readily  achievable in newly constructed
plants since a  number  of  existing  well  operated  plants  are
meeting  them.    (For  the actual data, see Section X.)  However,
the guidelines for the  Best  Available  Technology  Economically
Achievable should be kept in mind; it may be a practical approach
to   design   a  plant  which  approaches  the  1983  guidelines.
Consideration should also be given to land disposal, which is  no
discharge;  in  many  cases  this will be the most attractive and
economical  option,  particularly  for  small  rendering  plants.
Table 28 shows the estimated costs for new sources to achieve the
new source performance standards.
                     Table 28.  Investment and Operating Costs
                              for New Source Performance Standards

Plant Size
Small
Medium
Large
Waste Water Treatment System Costs
Investment
Cost
$
38,000
78,000
133,000
Annual Cost
Total
$/yr
20,500
30,600
44,100
C/kg
(C/lb)
0.42
(0.19)
0.13
(0.06)
0.07
(0.03)
Operating Cost
Total
$/yr
14,700
18,800
24,100
C/kg
(C/lb)
0.31
(0.14)
0.09
(0.04)
0.04
(0.02)
          Identification  of  New  Source  Control  Technology

 The  control  technology is the same  as  that  identified as the Best
 Practicable   Control  Technology  Currently  Available (see Section
 IX).   However,  certain steps that will be necessary to  meet  the
 1983   guidelines   should   be   considered  and,   where  possible,
 incorporated.   These  include:

      o    Segregation of drainage from trucks  and raw materials,
           hide  curing waste, blood  water, and  tank water from
           other waste waters for  special treatment.  This special
           treatment may  be  to eliminate these  wastes by adding
           them  to  the raw material  as  it enters a cooker or by
           evaporating them  down to  a point  where they can be
           used  as  tankage for dry inedible  rendering.  Another
           special  treatment method  would be to steam sparge and
                                 160

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     screen some wastes before combining them with other
     waste waters.  Of course, the formal methods are the
     best for lowering the raw waste load and particularly
     the TKN and ammonia loads.

o    Materials recovery systems—catch basins, skimming tanks,
     air flotation, etc.—should provide for at least a 30-
     minute detention time of the waste water.

o    Reuse of treated waters for operating barometric leg
     condensers rather than fresh water.  This minimizes
     net waste water volumes for a given size of treatment
     system and permits a longer effective residence time.

o    Removal of grease and solids from the materials recovery
     system on a continuous or regularly scheduled basis to
     permit optimum performance.

o    Provide adequate cooling of condensables to ensure that
     the temperature of the waste water in the materials
     recovery system does not exceed 52°C (125°F).  A tempera-
     ture below 38°C (100°F) is even better.  This allows for
     improved grease recovery, and minimizes odor problems.

o    Scrape, shovel or pick up by other means as much as
     possible of material spills before washing the floors
     with hot water.

o    Repair equipment leaks as soon as possible.

o    Provide for regularly scheduled equipment maintenance
     programs.

o    Avoid over-filling cookers.

o    Provide and maintain traps in the cooking vapor lines
     to prevent overflow to the condensers.  This is
     particularly important when the cookers are used to
     hydrolyze materials.

o    Contain materials when equipment failure occurs and
     while equipment is being repaired.

o    Plug sewers  and provide  supervision when unloading or
     transferring raw blood.

o    Provide  by-pass controls  for controlling pressure
     reduction  rates of  cookers  after hydrolysis.   Cooker
     agitation  may have  to  be stopped also,  during  cooker
     pressure bleed-down to prevent  or  minimize  material
     carry-over.

 o    Minimize water use for scrubbers by recycling  and reuse.

 o    Do not add uncontaminated water to the contaminated


                           161

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          water to be treated.

     o    By-pass the materials recovery process with low grease-
          bearing waste waters.

     o    Provide for flow equalization (constant flow with time)
          through the materials recovery system.

In addition, the following end-of-process treatments should be
considered.

     o    Land disposal (irrigation, evaporation) wherever possible;
          this should be a prime consideration, especially for
          economic reasons.

     o    Sand filter or equivalent for polishing the effluent
          from secondary treatment.


              Rationale for Selection of New Source
                      Performance Standards

The BOD5, SS, grease and fecal colifcrm limits are  discussed  in
Section   IX  on  the  rationale  for  Best  Practicable  Control
Technology Currently Available.


The ammonia limit of 0.17 kg/kkg RM is the average ammonia  value
for  the  nine plants whose data are presented in Section X.  Six
of those nine plants meet this limit.  Three are not meeting  the
limit because of poor practices:  two are allowing too much blood
to  enter  the  sewer,  and  the third is adding nutrients to the
lagoons to form a grease cover on the anaerobic lagoon.  A  total
Kjeldahl  nitrogen   (TKN)   limit  was not established because the
majority of the TKN in the effluent is ammonia  (the rest, organic
nitrogen) and restricting ammonia will restrict the TKN  load  in
the effluent.
                    Pretreatment Requirements

No  constituents  of  the effluent discharged from a plant within
the offsite  rendering  industry  have  been  found  which  would
interfere with, pass through, or otherwise be incompatible with a
well  designed  and  operated  publicly owned activated sludge or
trickling filter waste  water  treatment  plant.   The  effluent,
however,  should  have passed through materials recovery  (primary
treatment) in the plant to remove settleable solids and   a  large
portion   of   the   grease.   The  concentration  of  pollutants
acceptable to the treatment plant is dependent  on  the   relative
sizes  of  the  treatment  facility  and the effluent volume from
independent rendering plants, and  must  be  established  by  the
treatment  facility.  It is possible that grease remaining in the
rendering effluent will cause difficulty in the treatment system;
trickling  filters  appear  to  be  particularly  sensitive.    A


                             162

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concentration of 100 mg/1 is often cited as a limit, and this may
require  an  effective  air  flotation  system in addition to the
usual catch basins.  If the waste strength in terms of BOD5  must
be  further  reduced,  various  components of secondary treatment
systems can be used such as anaerobic contact,  aerated  lagoons,
etc., as pretreatment.
                               163

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                           SECTION XII

                         ACKNOWLEDGMENTS

The  program  was  conducted under the overall supervision of Dr.
E.E.  Erickson.  John Pilney was the  Project  Engineer;  he  was
assisted by Messrs R.J. Reid and R.J. Parnow.  Special assistance
was  provided  by North Star staff members:  Messrs R.H. Forester
and A.J. Senechal.

The contributions and advice of Mr.  William  H.  Prokop  of  the
National  Renderers  Association  and  of  their plant operations
committee and of Dr. H.O. Halvorson are gratefully acknowledged.

Special thanks are due Mr. Jeffery D. Denit, Effluent  Guidelines
Division for his guidance in the direction of the program and for
his  invaluable  help in carrying out all aspects of the research
program.

The cooperation of the independent rendering industry is  greatly
appreciated.   The National Renderers Association and its members
deserve special mention, as do several  companies  that  provided
information  and cooperation in plant visits and on-site sampling
programs.

The help  of  Dr.  Dwight  Ballinger  of  EPA  in  Cincinnati   in
establishing  sampling  and testing procedures used for the field
verification stuides was also appreciated.

Many state and local agencies were also  most  helpful  and  much
appreciated.
                               165

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                          SECTION XIII

                           REFERENCES

1.     standard Industrial Classification Manual, Executive Office
of  the  President,  Office  of  Management  and   Budget,   U.S.
Government Printing Office, Washington, 1972.

2.     Dion,  J.A.,  Osag,  T.R.,  Bunyard, F.L., and Crane, G.B.,
Control of Odors from Inedible Rendering Plants:  An  Information
Document, Environmental Protection Agency, Washington, 1973.

3.     "Uniqueness  of the Rendering Industry," National Renderers
Association, unpublished, undated.

4.    1967 Census of Manufactures,  Bureau  of  the  Census,  U.S.
Department   of   Commerce,   U.S.  Government  Printing  Office,
Washington, 1972.

5.    Pollution Control  Costs  and  Research  Priorities  in  the
Animal   Slaughtering   and   Processing   Industries,   National
Industrial Pollution Control Council,  U.S.  Government  Printing
Office, Washington, June 1973.

6.      Protein   Conversion   Equipment,  Chemetron  Corporation,
Chicago, 1973.

7.    Personal communication. National Renderers Association.

8.     Development  Document  for  Proposed  Effluent  Limitations
Guidelines  and New Source Performance Standards for the Red Meat
Processing Segment of the Meat Product and  Rendering  Processing
Point  Source  Category,  U.S.  Environmental  Protection Agency,
Report No. 4UO/173/012, Washington, October 1973.

9.    Doty, D.M., et al., Investigation of  Odor  Control  in  the
Rendering  Industry,  by  Fats  and Proteins Research Foundation,
Incorporated, for Environmental Protection Agency, Report No. PB-
213 386, National  Technical  Information  Service,  Springfield,
Va., October 1972.

10.    Prokop,  William  H.,  "The Rendering Industry and  Ecology
Control," National Renderers Association  for presentation  at the
2nd Annual International  Food  and  Beverage  F.I.D.   Symposium,
Montreal, June 1973.

11.    Meat  Industry  Waste  Management,  Robert  S.   Kerr Water
Research Center, Ada, Oklahoma, Environmental Protection   Agency,
June 1972.

12.    Development  Document  for Effluent Limitations  Guidelines
and  standards   of  Performance  for   the  Leather   Tanning  and
Finishing   Industry, DRAFT, for the U.S. Environmental  Protection
Agency,  June  1973.
                              167

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13.   Basics of Pollution Control, Gurnham & Associates, prepared
for Environmental Protection Agency Technology Transfer  Program,
Kansas City, Mo., March 7-8, 1973, Chicago.

14.    Public  Health  Service Drinking Water Standards, Revised,
1962, U.S. Department of  Health,  Education  and  Welfare,  U.S.
Public  Health  Service  Publication  No.  956,  U.S.  Government
Printing Office, Washington, 1962.

15.   Steffan, A.J., In-Plant Modifications to  Reduce  Pollution
and  Pretreatment  of  Meat  Packing Wastewaters for Discharge to
Municipal Systems, prepared for Environmental  Protection  Agency
Technology Transfer Program, Kansas City, Mo., March 7-8, 1973.

16.     Water   Quality  Improvement  by  Physical  and  Chemical
Processes, Earnest F. Gloyna  and  W.  Wesley  Eckenfelder,  Jr.,
Eds., University of Texas Press, Austin, 1970.

17.    Rosen,  G.D.,  "Profit  from  Effluent,"  Poultry Industry
(April 1971) .

18.   Personal communication, J. Hesler,  Greyhound  Corporation,
1973.

19.    Telephone communication with M. Hartman, Infilco Division,
Westinghouse, Richland, Virginia, May 1973.

20.   Upgrading Meat  Packing  Facilities  to  Reduce  Pollution:
Waste  Treatment  Systems,  Bell,  Galyardt,  Wells, prepared for
Environmental  Protection  Agency  Technology  Transfer  Program,
Kansas City, Mo., March 7-8, 1973, Omaha.

21.    Private  communication  from  Geo.  A.  Hormel  & Company,
Austin, Minnesota, 1973.

22.   Chittenden, Jimmie A.,  and  Wells,  W.  James,  Jr.,  "BOD
Removal  and  Stabilization  of Anaerobic Lagoon Effluent Using a
Rotating Biological Contactor,"  presented  at  the  1970  Annual
Conference, Water Pollution Control Federation, Boston.

23.    Gulp, Russell L., and Gulp, Gordon L. , Advanced Wastewater
Treatment, Van Nostrand Reinhold Company, New York, 1971.

24.   Babbitt, Harold E., and Baumann, E.  Robert,  Sewerage  and
Sewage  Treatment,  Eighth  Ed., John Wiley & Sons, Inc., London,
1967.

25.   Fair, Gordon Maskew, Geyer, John Charles, and Okun,  Daniel
Alexander,  Water  and  Wastewater Engineering:  Volume 2.  Water
Purification and Wastewater Treatment and Disposal, John Wiley  &
Sons, Inc., New York, 1968.

26.   Personal communication, H.O. Halvorson, 1973.
                             168

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27.    Fair, Gordon Maskew, Geyer, John Charles, and Okun, Daniel
Alexander, Water and Wastewater Engineering:   Volume  1.   Water
Supply and Wastewater Removal, John Wiley & Sons, Inc., New York,
1966.

28.    Eckenfelder,  W.  Wesley,  Jr., Industrial Water Pollution
Control, McGraw-Hill Book Company, New York, 1966.

29.    Eliassen,  Rolf  and  Tchobanoglous,   George,   "Advanced
Treatment Processes," Chemical Engineering  (October 14, 1968).

30.   Knowles, Chester L., Jr., "Improving Biological Processes,"
Chemical Engineering  (October 14, 1968).

31.   Personal communication, H.O. Halvorson, May 1973.

32.    Witherow,  Jack  L. ,  Small  Meat Packers Wastes Treatment
Systems, Presented at 4th National Symposium on  Food  Processing
Wastes, Syracuse, N.Y., March 26-28, 1973

33.     Personal   communication,   C.E.   Clapp,  United  States
Department  of  Agriculture,   Agricultural   Research   Service,
University of Minnesota, Minneapolis, May 1973.

34.    Personal  communication  with Lowell Hanson, Soil Science,
Agricultural Extension Service, University of Minnesota, 1973.

35.   Financial Facts About  the  Meat  Packing  Industry,  1971,
American Meat Institute, Chicago, August 1972.

36.    "Survey  of  Corporate  Performance:  First Quarter 1973,"
Business Week, p. 97  (May 12, 1973).

37.   Mckinney, Ross E.,  Microbiology  for  Sanitary  Engineers,
McGrawHill Book Company, New York, 1962.

38.   Frazier, W. C., Food Microbiology, 2nd Edition,  McGraw-Hill
Book Company, New York, 1967.
                              169

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                           SECTION XIV

                            GLOSSARY

"Act":   The  Federal  Water  Pollution Control Act Amendments of
1972.

Activated Sludge Process:  Aerated basin in  which  waste  waters
are mixed with recycled biologically active sludge for periods of
about 6 hours.

Aerated:   The  introduction and intimate contacting of air and a
liquid  by  mechanical  means  such  as  stirring,  spraying,  or
bubbling.

Aerobic:   Living  or occurring only in the presence of dissolved
or molecular oxygen.

Algae:  Major group of lower  plants,  single  and  multi-celled,
usually  aquatic  and  capable of synthesizing their foodstuff by
photosynthesis.

Ammonia Stripping:  Ammonia removal from  a  liquid,  usually  by
intimate contacting with an ammonia-free gas such as air.

Anaerobic:  Living or active only in the absence of free oxygen.

Bacteria:   Primitive  plants,  generally  free of pigment, which
reproduce by dividing in one, two, or three planes.   They  occur
as  single  cells,  chains,  filaments,  well-oriented groups, or
amorphous masses.

Biodegradable:  The condition of a substance which indicates that
the energy content of the substance can be lowered by the  action
of  biological  agents  (bacteria) through chemical reactions that
simplify the molecular structure of the substance.

Biological Oxidation:  The process whereby, through the  activity
of  living organisms in an aerobic environment, organic matter is
converted to more biologically stable matter.

Biological Stabilization:  Reduction in the net energy  level  of
organic   matter  as  a  result  of  the  metabolic  activity  or
organisms, so that further biodegradation is very slow.

Biological Treatment:  Organic waste treatment in which  bacteria
and/or   biochemical  action  are  intensified  under  controlled
conditions.

Blood Water  (serum):  Liquid remaining after coagulation   of  the
blood.

Slowdown:   A discharge of water from a system to prevent  a build
up of dissolved solids; e.g., in a boiler.


                              171

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BOD_5:  A measure of the oxygen consumption by  aerobic  organisms
over  a  five day test period at 20°C.  It is an indirect measure
of the concentration of biologically degradable material  present
in organic wastes contained in a water stream.

Category  and  Subcategory:   Divisions  of a particular industry
which possess  different  traits  that  affect  raw  waste  water
quality.

Chemical   Precipitation:   A  waste  treatment  process  whereby
substances dissolved in  the  waste  water  stream  are  rendered
insoluble  and  form  a  solid  phase  that settles out or can be
removed by flotation techniques.

Clarification:  Process of removing undissolved materials from  a
liquid,  specifically,  removal  of  solids either by settling or
filtration.

Clarifier:  A settling basin  for  separating  settleable  solids
from waste waters.

cm:  Centimeter.

Coagulant:   A  material,  which,  when added to liquid wastes or
water, creates a reaction which forms  insoluble  floe  particles
that  absorb and precipitate colloidal and suspended solids.  The
floe particles can be removed by sedimentation.  Among  the  most
common  chemical  coagulants  used in sewage treatment are ferric
sulfate and alum.

Coanda Phenomenon:  Tendency of a flowing fluid to  adhere  to  a
curved surface.

COD  -  Chemical  Oxygen  Demand:   An  indirect  measure  of the
biochemical load imposed on the oxygen  resource  of  a  body  of
water  when  organic  wastes  are  introduced  into the water.  A
chemical test is used to determine COD of waste water.

Condensables:  Cooking vapors capable of being condensed.

Condensate:  The liquid produced by condensing rendering  cooking
vapors.

Contamination:   A  general term signifying the introduction into
water of microorganisms, chemical, organic, or inorganic  wastes,
or sewage, which renders the water unfit for its intended use.

Cracklings:   The crisp solid residue left after the fat has been
separated from the fibrous tissue in rendering lard or tallow.

Denitrification:  The process involving the faculative conversion
by anaerobic bacteri  of  nitrates  into  nitrogen  and  nitrogen
oxides.
                              172

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Digestion:   Though  "anaerobic"  digestion  is  used,  the  term
digestion commonly refers to the anaerobic breakdown  of  organic
matter  in  water  solution  or  suspension  into simpler or more
biologically stable compounds or both.   Organic  matter  may  be
decomposed to soluble organic acids or alcohols, and subsequently
converted  to such gases as methane and carbon dioxide.  Complete
destruction of organic solid materials by bacterial action  alone
is never accomplished.

Dissolved  Air Flotation:  A process involving the compression of
air and liquid, mixing to  super-saturation,  and  releasing  the
pressure to generate large numbers of minute air bubbles.  As the
bubbles  rise  to  the surface of the water, they carry with them
small particles that they contact.  The process  is  particularly
effective for grease removal.

Dissolved  Oxygen:   The  oxygen  dissolved  in sewage, water, or
other liquid, usually expressed as milligrams  per  liter  or  as
percent of saturation.

Dry  Rendering:   Cooking of inedible raw materials to remove all
excess raw material moisture by externally applied heat.

Edible:  Products that can be used for human consumption.

Effluent:  Liquid which flows from a containing space or  process
unit.

Equalization  Tank:   A  means  of  liquid  storage capacity in a
continuous flow system, used  to  provide  a  uniform  flow  rate
downstream in spite of fluctuating incoming flow rates.

Eutrophication:   Applies  to  lake  or  pond—becoming  rich  in
dissovled nutrients, with seasonal oxygen deficiency.

Evapotranspiration:   Loss  of  water  from  the  soil,  both  by
evaporation and by transpiration from the plants growing thereon.

Extended Aeration:  A form of the activated sludge process except
that the retention time of waste waters is one to three days.

Facultative  Bacteria:   Bacteria  which  can exist and reproduce
under either aerobic or anaerobic conditions.

Facultative Decomposition:  Decomposition of  organic  matter  by
facultative microorganisms.

Fat:  Refers to the rendering products of tallow and grease.

Fatty Acid:  A type of organic acid derived from fats.

Filtration:   The  process  of  passing a liquid through  a porous
medium for the  removal  of  suspended  material  by   a   physical
straining action.
                              173

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Finger  Dikes:   Barriers or walls extending out into lagoonsin
waste  water  treatment—to  prevent  or  minimize  the  flow  of
incoming   water   directly  to  the  outlet  and  thereby  short
circuiting the treatment process.

Floe:  A mass formed by the  aggregation  of  a  number  of  fine
suspended particles.

Flocculationt   The  process  of forming larger flocculant masses
from a large number of finer suspended particles.

Grease:  Fat that has a titre   (or  melting  point)  below  40°C.
Grease is produced from poultry and hot fat.

Hydrolyzing:  The reaction involving the decomposition of organic
materials  by  interaction with water in the presence of acids or
alkalines.  Hog hair and feathers for example, are hydrolyzed  to
a proteinaceous product that has some feed value.

Inedible:  Products that can not be used for humar consumption.

Influent:   A  liquid  which  flows  into  a  containing space or
process unit.

Ion Exchange:  A reversible chemical reaction between a solid and
a liquid by means of which ions may be interchanged  between  the
two.    It  is  in  common  use  in  water  softening  and  water
deionizing.

Isoelectric point:  The value of the pH of a  solution  at  which
the soluble protein becomes insoluble and precipitates out.

kg:  Kilogram or 1000 grams, metric unit of weight.

kkg:  1000 kilograms.

Kjeldahl  nitrogen:  A measure of the total amount of nitrogen in
the ammonia and organic forms in waste water.

KWH:   Kilowatt-hours;  a  measure  of  total  electrical  energy
consumption.

Lagoon:    An  all-inclusive  term  commonly  given  to  a  water
impoundment in which organic wastes are stored or  stabilized  or
both.

Low  Temperature  Rendering:   A  rendering  process in which the
cooking  is  conducted  at  a  low  temperature  which  does  not
evaporate  the raw material moisture.  Normally used to produce a
high quality edible product such as lard.

m:  Meter; metric unit of length.

Meal:  A coarsely ground proteinaceous product of rendering  made
from such animal by-products as meat, bone, and feathers.


                               174

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mg/1:   Milligrams  per  liter;  approximately  equals  parts per
million; a term used to indicate concentration  of  materials  in
water.

MGD or MGPD:  Million gallons per day.

Microstrainer/Microscreen:   A  mechanical filter consisting of a
cylindrical surface of metal filter fabric with openings of 20-60
micrometers in size.

mm:  Millimeter = 0.001 meter.

Municipal Treatment:  A city- or community-owned waste  treatment
plant for municipal and possible industrial waste treatment.

New  Source:   Any building, structure, facility, or installation
from which there is or may be a discharge of pollutants and whose
construction is commenced after the publication of  the  proposed
regulations.

Nitrate,  Nitrite:   Chemical  compounds  that  include  the NO_3-
(nitrate) and NO2-  (nitrite) ions.  They are composed of nitrogen
and oxygen, are nutrients for growth of  algae  and  other  plant
life, and contribute to eutrophication.

Nitrification:  The process of oxidizing ammonia by bacteria into
nitrites and nitrates.

No  Discharge:   No  discharge of effluents to a water course.   A
system of land disposal with no run-off or total recycle  of  the
waste water may be used to achieve it.

Noncondensables:  Cooking gases that can not be condensed and are
usually very odorous.

Nonwater   Quality:    Thermal,   air,   noise   and   all  other
environmental parameters except water.

Offal:  The parts of a butchered animal removed  in  eviscerating
and trimming that may be used as edible products or in production
of inedible by-products.

Off-Gas:   The  gaseous  products of a process that are collected
for use or more typically vented directly, or  through  a  flare,
into the atmosphere.

Organic  Content:   Synonymous  with  volatile  solids except for
small  traces  of  some  inorganic  materials  such  as   calcium
carbonate   which  will  lose  weight  at  temperatures  used  in
determining volatile solids.

Oxidation Lagoon:  Synonymous with aerobic or aerated  lagoon.

Oxidation Pond:  Synonymous with aerobic lagoon.
                            175

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Packed Tower:   Equipment  used  in  rendering  plants  for  odor
control.   A  cylindrical  column  loaded with a packing material
used to increase the contact area between scrubbing solution  and
odorous air.

pH:  A measure of the relative acidity or alkalinity of water.  A
pH  of 7.0 indicates a neutral condition.  A greater pH indicates
alkalinity and a lower pH indicates acidity.  A one  unit  change
in  pH  indicates  a ten fold change in concentration of hydrogen
ion concentration.

Point Source:  Regarding waste water, a single plant with a waste
water stream discharging into a receiving body of water.

Polishing:  Final treatment stage before discharge of effluent to
a water course.  Carried out in  a  shallow,  aerobic  lagoon  or
pond,  mainly  to  remove  fine suspended solids that settle very
slowly.  Some aerobic microbiological activity also occurs.

Pollutant:  A substance which taints, fouls, or otherwise renders
impure or unclean the recipient system.

Pollution:  The presence of pollutants in a system sufficient  to
degrade the quality of the system.

Polyelectrolyte  Chemicals:   High  molecular  weight  substances
which dissociate into ions when  in  solution;  the  ions  either
being  bound  to  the  molecular  structure  or  free  to diffuse
throughout the solvent, depending on the sign of the ionic charge
and the type of electrolyte.  They are often used as flocculating
agents  in  waste  water  treatment,  particularly   along   with
dissolved air flotation.

Ponding:  A waste treatment technique involving the actual holdup
of all waste waters in a confined space.

ppm:   Parts  per  million,  a  measure  of concentration usually
expressed currently as mg/1.

Prebreaker:  A mechanical grinder used by  rendering  plants  for
size reduction of raw materials prior to cooking operations.

Pretreatment:   Waste  water  treatment located on the plant site
and upstream from the discharge to a municipal treatment system.

Primary waste treatment:  In-plant by-product recovery and  waste
water   treatment  involving  physical  separation  and  recovery
devices  such  as  catch  basins,  screens,  and  dissolved   air
flotation.

Raceway:   Circular  shaped  vat  containing brine, agitated by a
paddle wheel and used for brine curing of hides.

Raw Material Moisture:   Refers  to  the  water  content  of  raw
materials used in rendering.
                             176

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Raw  Waste:   The  waste water effluent  from the  in-plant  primary
waste  treatment system.

Recycle:  The return of a quantity of  effluent  from   a  specific
unit   or  process  to the feed stream  of that same  unit  including
the return of treated plant waste water  for several plant  uses.

Rendering:  Separation of fats and water from tissue by  heat   or
physical energy.

Return  on  Assets   (ROA):   A  measure  of potential  or realized
profit as a percent of the total assets  (or fixed assets)  used  to
generate the profit.

Return on investment (ROI):  A measure of potential  or  realized
profit as a percentage of the investment required to generate the
profit.

Reuse:   Referring  to  waste reuse.   The subsequent use of water
following an earlier use without restoring  it  to  the  original
quality.

Riprap:   A  foundation or sustaining wall, usually of stones and
brush, so placed on an embankment or a lagoon to prevent erosion.

RM:  Referring to the raw material used  in the rendering process.

Rotating  Biological  Contactor:   A   waste   treatment   device
involving  closely  spaced  lightweight  disks  which are rotated
through the waste water allowing aerobic microflora to accumulate
on each disk and thereby  achieving  a   reduction  in  the  waste
content.

Sand  Filter:   A filter device incorporating a bed of sand that,
depending on design, can be used in secondary or  tertiary  waste
treatment.

Screw  Press:   An extrusion device used to expel excess fat from
proteinaceous solids after cooking.

Scrubber:  Used as  an  odor  control  device  in  the  rendering
industry.   Operates  by  the  contacting of numerous droplets of
scrubbing solution with cdcrous air streams.

Secondary Treatment:  The waste treatment following  primary  in-
plant  treatment.  Typically involving biological waste reduction
systems.

Sedimentation Tank:  A tank or basin in  which  a  liquid   (water,
sewage,  liquid manure)  containing settleable suspended solids is
retained for a sufficient time so part of  the  suspended  solids
settle  out  by  gravity.    The  time interval that the liquid is
retained in the tank is called  "detention  period."   In  sewage
treatment,   the  detention  period  is  short  enough  to  avoid
putrefaction.

                            177

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Settling Tank:  Synonymous with sedimentation tank.

Sewage:  Water after it has been fouled by  various  uses.   From
the standpoint of source it may be a combination of the liquid or
water-carried  wastes  from  residences,  business buildings, and
institutions,   together   with   those   from   industrial   and
agricultural  establishments,  and with such groundwater, surface
water, and storm water as may be present.

Shock Load:  A quantity of waste water or pollutant that  greatly
exceeds  the  normal  discharged into a treatment system, usually
occurring over a limited period of time.

Skimmings:  Fats and flotable solids recovered from waste  waters
for  recycling  by catch basins, skimming tanks and air flotation
devices.

Sludge:  The accumulated settled sclids deposited from sewage  or
other  wastes, raw or treated, in tanks or basins, and containing
more or less water to form a semiliquid mass.

Slurry:  A solids-water mixture, with sufficient water content to
impart fluid handling characteristics to the mixture.

Stick or Stickwater:  The  concentrated   (thick)   liquid  product
from the evaporated tank water from wet rendering operations.  It
is added to solids and may be further dried for feed ingredients.

Stoichiometric  Amount:   The amount of a substance involved in a
specific chemical reaction, either as a reactant or as a reaction
product.

Surface Waters:  The waters of the United  States  including  the
territorial seas.

Suspended  Solids   (SS):  Solids that either float on the surface
of, or are  in  suspension,  in  water;  and  which  are  largely
removable   by   laboratory   filtering   as  in  the  analytical
determinate cf SS content of waste water.

Tallow:  Fat that has a titre  (melting point) of 40°C or  higher.
Tallow is produced from beef cattel and sheep fat.

Tankage:  Dried animal by-product residues used as feedstuff.

Tankwater:   The  water  phase resulting from rendering processes
usually occurring in wet rendering.

Tertiary Waste Treatment:  Waste treatment systems used to  treat
secondary   treatment  effluent  and  typically  using  physical-
chemical technologies to effect waste reduction.  Synonymous with
"advanced waste treatment."
                            178

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Total Dissolved Solids  (TDS):  The solids content of waste  water
that is soluble and is measured as total solids content minus the
suspended solids.

Wet  Rendering:   Cooking  with  water or live steam added to the
material under pressure.  This process produces tankwater.

Zero Discharge:  The discharge of  no  pollutants  in  the  waste
water stream of a plant that is discharging into a receiving body
of water.
                                 179

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                                TABLE 29

                             METRIC TABLE

                           CONVERSION TABLE

MULTIPLY (ENGLISH UNITS)                   by

    ENGLISH UNIT      ABBREVIATION    CONVERSION
                                     TO OBTAIN (METRIC UNITS)

                           ABBREVIATION   METRIC UNIT
acre
acre - feet
British Thermal
  Unit
British Thermal
  Unit/pound
cubic feet/minute
cubic feet/second
cubic feet
cubic feet
cubic inches
degree Fahrenheit
feet
gallon
gallon/minute
horsepower
inches
inches of mercury
pounds
million gallons/day
mile
pound/square
  inch (gauge)
square feet
square inches
ton (short)
yard
ac              0.405
ac ft        1233.5

BTU             0.252

BTU/lb          0.555
cfm             0.028
cfs             1.7
cu ft           0.028
cu ft          28.32
cu in          16.39
°F            0.555(°F-32)*
ft              0.3048
gal             3.785
gpm             0.0631
hp              0.7457
in              2.54
in Hg           0.03342
Ib              0.454
mgd         3,785
mi              1.609

psig     (0.06805 psig +1 )*
sq ft           0.0929
sq in           6.452
ton             0.907
yd              0.9144
ha           hectares
cu m         cubic meters

kg cal       kilogram - calories

kg cal/kg    kilogram calories/kilogrc
cu m/min     cubic meters/minute
cu m/min     cubic meters/minute
cu m         cubic meters
1             liters
cu cm        cubic centimeters
°C           degree Centigrade
m            meters
1             liters
I/sec        liters/second
kw           killowatts
cm           centimeters
atm          atmospheres
kg           kilograms
cu m/day     cubic meters/day
km           kilometer

atm          atmospheres (absolute)
sq m         square meters
sq cm        square centimeters
kkg          metric ton (1000 kilograir
m            meter
* Actual conversion, not a multiplier
                                            180

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