EPA 440/1-73/028
          DEVELOPMENT DOCUMENT FOR
  PROPOSED  EFFLUENT LIMITATIONS GUIDELINES
   AND NEW SOURCE PERFORMANCE STANDARDS
                    FOR THE
             GRAIN  PROCESSING
                  SEGMENT OF THE
                   GRAIN MILLS
               POINT SOURCE CATEGORY
           UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                     DECEMBER 1973

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              Publication Notice

This is a developemnt document for proposed effluent limitations
guidelines and new source performance standards.   As such, this
report is subject to changes resulting from comments received
during the period of public comments of the proposed regulations.
This document in its final form will be published at the time the
regulations for this industry are promulgated.

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               DEVELOPMENT DOCUMENT


                       for

    PROPOSED EFFFLUENT LIMITATIONS GUIDELINES

                       and

         NEW SOURCE PERFORMANCE STANDARDS

                     for the



         GRAIN PROCESSING SEGMENT OF THE

        GRAIN MILLS POINT SOURCE CATEGORY

                  Russell Train
                  Administrator

                 Robert L. Sansom
Assistant Administrator for Air and Water Programs
                   Allen Cywin
      Director, Effluent Guidelines Division

                 Robert J. Carton
                 Project Officer
                  December 1973
           Effluent Guidelines Division
         Office of Air and Water Programs
      U. S. Environmental Protection Agency
             Washington, D. C.  20U60
                       Protection Ae«oy

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AGENCY

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                                ABSTRACT


This document presents the findinqs of an extensive study of  th-  qrain
milling  industry by the Environmental Protection Agency for the purpose
of developing effluent  limitations  guidelines.  Federal  standards  of
performance,  and  pretr^atment standards for the industry, to implement
Sections SOU, 306, and 3')7 of the "Act."

Effluent limitations guiielines contained in this document set forth thf
dpqr^e of effluert reduction attainable through the apnlication  of  ^h0
bf-st  practicable  contr >l technology currently availanl<= and th:- degree
ot effluent reduction attainable through the  application  of  the  fc^st
available  technology  economically achievable which must be achieved uy
existing point sources by July 1, 1977 and July 1,  1983,  respectively.
The  Standards of Performance for new sources contained herein set forth
the degree  of  effluent  reduction  which  is  achievable  through  th-
application  of  the  best  available  demonstrated  control technology,
processes, operating methods, or other alternatives.

Separate effluent limitations guidelines are described for the follcwino
subcitegories cf the grain  milling  point  source  category;  corn  w~~
milling,  corn  dry  milling,  normal  wheat flour milling, bulgur whear
flour milling, normal  rice  milling,  and  parboiled  rice  processinq.
Treatment  technologies  are recommended for the four subcategories wit 1;
allowable discharges: corn wet milling, corn dry milling,  bulgur  wheat
flow  milling,  and  parboiled  rice  processing.   They  are  generally
similar, and may include equalization, and biological treatment followed
by clarification.  In order to attain the  1983  limitations  additional
solid   removal   techniques   will  be  necessary.   The  standards  of
performance for new sources are the same as the 1983 limitations.

The cost of achieving these  limitations  are  described.   The  highest
costs  are  in the corn wet milling subcategory.  For a typical corn wet
milling plant with a grind of 60,000 bu/day, the investment cost for the
entire treatment system to meet the 1977 limitations is $2,5<4U,000.   An
additional  $288,000  will  be  necessary  to install the solids removal
techniques to meet the 1983  standards.   The  economic  impact  of  th0
proposed  effluent  limitations  guidelines and standards of performance
are contained  in  a  separate  report  entitle  "Economic  Analysis  of
Proposed Effluent Guidelines-Grain Milling Industry."

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

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                           TABLE OF CONTENTS


SECTION                                                         page

I        Conclusions                                             1

II       Recommendations                                         3

III      Introduction                                            5

              Purpose and Authority                              5
              Summary of Methods                                 6
              Source of Data                                     7
              General Description of Industry                    8
              Production Processes                               17
              Waste Water Considerations                         27

IV       Industry Categorization                                 31

              Factors Considered                                 31

V        Water Use and Waste Water Characterization              35

              Introduction                                       35
              Corn Wet Milling                                   35
              Corn Dry Milling                                   54
              Wheat Milling                                      56
              Rice Milling                                       57

VI       Selection of Pollutant Parameters                       59

              Major Control Parameters                           59
              Additional Parameters                              60

VII      Control and Treatment Technology                        63

              Introduction                                       63
              Corn Wet Milling                                   63
              Corn Dry Milling                                   73
              Wheat Milling                                      74
              Rice Milling                                       75

VIII     Cost, Energy, and Non-Water Qaulity Aspects             77

              Representative Plants                              77
              Terminology                                        77
              Cost Information                                   78
              Non-Water Quality Aspects                          85

IX       Effluent Reduction Attainable Through the  Ap-           87
           plication of the Best Practicable Control
                               iv

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           Technology Currently Available - Effluent
           Limitations Guidelines

              Introduction                                       87
              Effluent Reduction Attainable Through the          87
                Application of Best Practicable Control
                Technology Currently Available
              Identification of Best Practicable control         88
                Technology Currently Available
              Rationale for the Selection of Best                90
                Practicable Control Technology Currently
                Available
              Restraints on the Use of Effluent Limitations Guidelines
                                                                 95
X        Effluent Reduction Attainable Through the Ap-
           plication of the Best Available Technology            97
           Economically Achievable - Effluent Limita-
           tions Guidelines

              Introduction                                       97
              Effluent Reduction Attainable Through the          97
                Application of the Best Available Tech-
                nology Economically Achievable
              Identification of Best Available Technology        98
                Economically Achievable
              Rationale for the Selection of the Best            99
                Available Technology Economically
                Achievable

XI       New Source Performance Standards                        103

              Introduction                                       103
              New Source Performance Standards                   103
              Rationale for the Selection of New Source          104
                Performance Standards

XII      Acknowledgments                                         107

XIII     References                                              109

XIV      Glossary                                                113

         Conversion Table                                        115

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                                FIGURES

NUMBER                                                        page

    1    The Corn Wet Milling Process                          18

    2    The Corn Dry Milling Process                          21

    3    The Wheat Milling Process                             23

    4    The Bulgur Process                                    24

    5    The Rice Milling Process                              26

    6    The Parboiled Rice Process                            28

    7    Basic Milling Operations in a Typical
           Corn Wet Mill                                       37

    8    Finished Starch Production in a Typical
           Corn Wet Mill                                       38

    9    Syrup Production in a Typical
           Corn Wet Mill                                       39

   10    Effect of Wet corn Milling Plant Age on
           Average BOD5 Discharged                             47

   11    Quantity of Waste Water Discharged by
           Corn Wet Milling Plants                             49

   12    Average BODJ Discharged as a Function of
           Corn Wet Mill Capacity                              50

   13    Average Suspended Solids Discharged as a
           Function of Corn Wet Mill Capacity                  51

   14    Average BOD5 Discharged as a Function of
           Waste Water Volume                                  52

   15    Average Suspended Solids as a Function of
           Waste Water Volume                                  53
                              vi

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                                 TABLES


NUMBER                                                            Page

    1    Uses of Corn Grown in the United States                   9

    2    Composition by Dry Weight of Yellow Dent Corn            10

    3    Corn Wet Milling Companies and Plants                    12

    U    Bulgur Mills - Locations and Estimated Capacities        14

    5    Parboiled Pice Milling Companies                         16

    6    First and Second Effect Steepwater Condensate
           Waste Water Characteristics                            40

    7    Finished Starch Production, Waste Water
           Characteristics                                        41

    8    Individual Process Waste Loads, Corn Wet Milling         42

    9    Corn Syrup Cooling, Waste Water Characteristics          43

   10    Total Plant Raw Waste Water Characteristics,
           Corn Wet Milling                                       44

   11    Waste Water Characteristics Per Unit of Raw
           Material, Ccrn Wet Milling                             46

   12    Waste Water Characteristics, Corn Dry Milling            55

   13    Waste Water Characteristics, Bulgur Production           56

   14    Waste Water Characteristics, Parboiled Rice
           Milling Processing                                     57

   15    Effluent Reduction Attainable Through the Appli-
           cation of Best Practicable Control Technology
           Currently Available                                    88

   16    Effluent Reduction Attainable Through the
           Application of Best Available Technology
           Economically Achievable                                98

   17    New Source Performance Standards                        104
                             vii

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                               SECTION I

                              CONCLUSIONS

The  segment  of  the  grain  milling  industry  that is covered ir. thir7
document (Phase I)  has been classified  into  six  subcategories.   Thi?
categorization  is based on the type cf grain and manufacturing process.
Available information on factors such as age and size of plant,  product
mix,  and waste control technologies does not provide a sufficient basi?
for additional subcategorization.

The subcategories of the grain milling industry are as follows:

    1.   Corn wet milling
    2.   Ccrn dry milling
    3,   Normal wheat flour milling
    4.   Bulgur wheat flour milling
    5.   Normal rice milling
    6.   Parboiled rice processing

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                               SECTION II
                            RECOMMENDATIONS

The recommended effluent limitations for the waste water  parameter?  of
significance  are  summarized  below  for the subcategories of the gr^in
milling industry covered in this document.  These values  represent  the
maximum  average allowable loading for any 30 consecutive calendar days.
Excursions above these levels should be permitted with a  maximum  daily
average of 3.0 times the average 30-day values listed below.

The  effluent  limitations  to  be  achieved  with  the best practicable
control technology currently available are as follows:
                          BD
                     §usp_ended_Solids
Corn wet rrilling
Corn dry milling
Normal wheat flour
  milling
Bulgur wheat flour
  milling
Normal rice milling
Parboiled rice
  milling
0.893
0.071
0.0083
0.140
  50.0
   4.0
0.625
0.062
35.0
 3.5
no discharge of process wastes

   0.5       0.0083     0.5
no discharge of process wastes
   0.014
0.080
 0.008
                                 pP
6-9
                   6-9
6-9
Using the best available control technology economically achievable
the effluent limitations are:
                          BOD
Corn wet milling
Corn dry milling
Normal wheat flour
   milling
Eulgur wheat flour
   milling
Normal rice milling
Parboiled rice
   milling
0.357
0.0357
0.0050
0.070
  20.0
   2.0
0.179
0.0179
10.0
 1.0
no discharge of process wastes

   0.3       0.0033     0.2
no discharge of process wastes
   0.007
0.030
 0.003
                                         pH
6-9
6-9
                   6-9
6-9
The recommended new source  performance  standards  correspond,  in  all
instances,  to  the  limitations  defined  above  for the best available
control technology economically achievable.

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                              SECTION III

                              INTRODUCTION


PURPOSE ANC AUTHORITY

Section 301 (b)  of the Act requires the achievement  by  not  later  than
July  1,  1977,  of  effluent  limitations for point sources, other than
publicly cwned treatment works, which are based on  the  application  of
the  best  practicable control technology currently available as defined
by the Administrator pursuant to Section 30^ (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  owner!
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 1-h^
discharge  of  all  pollutants,  as  determined   in   accordance   with
regulations  issued  by  the Administrator pursuant to Section 304 (t) 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 efflu^n*-
reduction which the Administrator determines to  be  achievable  through
the  application  of the best available demonstrated control technoloay,
processes, operating methods, or other  alternatives,  including,  where
practicable, a standard permitting no discharge of pollutants.

Section  304(fc)  of the Act requires the Administrator to publish within
one year of enactment of the Act, regulations providing  guidelines  for
effluent  limitations  setting  forth  the  degree of effluent reduction
attainable through the  application  of  the  best  practicable  control
technology  currently  available  and  the  degree of effluent reduction
attainable through the application of  the  best  control  measures  and
practices  achievable  including  treatment techniques, process and pro-
cedure 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  grain  milling  source
category.

Section 306 of the Act requires the Administrator, within one year after
a  category  of  sources  is  included  in  a list published pursuant to
Section 306 (b)  (1)  (A)  of the Act, to propose  regulations  establishing
Federal   standards   of   performances  for  new  sources  within  such
categories.  The Administrator published  in  the  Federal  Register  of
January  16,  1973  (38  F.  R.  1624),  a list of 27 source categories.
Publication of the list constituted announcement of the  Administrator's
intention  of  establishing, under Section 306, standards of performance
applicable to new sources within  the  grain  milling  source  category,
which was includedd within the list published January 16, 1973.

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SUMMARY  OF  METHODS  USED  FOR  DEVELOPMENT OF THE EFFLUENT LIMITATIONS
GUIDELINES AND STANDARDS OF PERFORMANCE

The effluent limitations guidelines and standards  of  performance  pro-
posed  herein  were developed in the following manner.  The point source-
category was first categorized for the purpose  of  determining  whether
separate   limitations  and  standards  are  appropriate  for  different
segments within a point source  category.    Such  subcategorizat.ion  was
based  upon  raw  material used, product produced, manufacturing process
employed, and other factors.   The raw  waste  characteristics  for  each
subcategory  were then identified.  This included an analysis of (1) the
source and volume of water used in the process employed and the  sources
of  waste  and  waste  waters  in  the  plant;  and  (2)  the constituents
(including thermal)  of all waste waters including toxic constituents and
other constituents which result in taste,  odor, and order, and color  in
water  or  aquatic  organisms.   The  constituents  of waste waters that
should be subject to effluent limitations  guidelines  and  standards  of
performance were identified.

The  full  range  of  control and treatment technologies existing within
each subcategory was identified.  This  included  an  identification  of
each  distinct  control and treatment technology, including both inplanr
and end-of-process technologies, which are existent or capable of  being
designed  for  each  subcategory.  It also included an identification in
terms  of  the  amount  of  constituents   (including  thermal)  and  tne
chemical, physical, and biological characteristics of pollutants, of th°
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  availabler"  "best  available technology
economically achievable" and the "best  available  demonstrated  control
technology,  processes,  operating  methods, or other alternatives."  In
identifying such technologies, various factors were  considered.   These
included  the total cost of application of technology in relation to the
effluent reduction benefits to be achieved from  such  application,  the
age  of  equipment  and  facilities  involved, the 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.

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SOURCES OF DATA
The data for identification and analyses were derived frcm a  number  of
sources.   These  sources  included  published  literature, previous EPA
technical  publications  on  the  industry,  a   voluntary   information
retrieval form distributed to the Corn Refiners Association and to ether
grain  millers,  information  contained  in Corps of Engineers discharge
permit  applications,  and  on-site  visits,  interviews,  and  sanplina
programs  at  selected  grain  milling  facilities throughout the United
States.  A more detailed explanation of the data sources is giver trlow.
All  references  used  in  developing  the  guide  lines  for   effluent
limitations and standards of performance for new sources reported herein
are included in Section XIII of this document.

During  this  study  the  trade  associations  connected  with the grain
milling subcategories covered  by  this  study  were  contacted.   These
associations are listed below:
Milling_subcategorv.

Wet Corn
Dry Ccrn
Normal Wheat Flour
Bulgur Wheat Flour
Rice, Normal & Parboiled
                                Association

                                Corn Refiners Association, Inc.
                                American Corn Millers Federation
                                Millers National Federation
                                Assoc. of Operative Millers
                                National Soft Wheat Millers Association
                                Protein Cereal Products Institute
                                Rice Millers Association
These  associations  were  informed of the nature of the study and their
assistance was requested.  Subsequently a voluntary data retrieval  form
was  made available to them and also to individual plants.  This form is
shown in Table   .   The completed forms provided a more detailed  source
of   information   about  the  various  plants  including  manufacturing
processes,  data  on  raw  materials  and   finished   products,   waste
characterization  and  sources, waste treatment, and water requirements.
All of the existing plants in the corn wet milling, bulgur  wheat  flour
milling, and rice milling subcategories were covered.  Based on the 1971
Directory  of  the  Northwestern  Millers  there  are 126 corn dry mills
listed.  The plants contacted comprise 70-75 percent of  corn  processed
by  the  corn  dry  milling  industry.  An unknown percent of the normal
wheat flour milling industry was contacted.  A summary of the plants who
responded and those forms with usable data are shown below.
                   Retrieval Forms
Industry

Corn Wet Milling
Corn Dry Milling
Wheat Milling  "
Eulgur Milling
Rice Milling:
  Ordinary Process
  Parboiled Process
                                         Retrieval Forms
                                          Returned with
                                          UsableData
                        16
                         9
                        47
                         6
                        29
                        28
                         5
                                              15
                                               4
                                              20
                                               2
                                               9
                                               8
                                               2

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RAPP applications to the Corps of Engineers for discharges together with
computerized FAPP data, supplied by EPA,  were also used as a  source  of
data.   These  data included the identification of the plant,  the number
of waste discharge points, the volumes of discharge, and  the  character
and  quantity  of  waste.   The  number  of sources included in the FAPP
applications was seven in the corn wet  milling  industry,  two  in  the
normal wheat milling industry, and one in the parboiled rice industry.

Plant  visits  provided information about the manufacturing process, the
distribution of water,  sources  of  wastes,  type  of  equipment  used,
control  of water flows, in-plant waste control, and effluent treatment.
A total of eleven plants were visited in the following subcategories:

    Industry               Tota1_P1 ant s visited

    Corn Wet Milling               5
    Corn Dry Milling               1
    Normal Wheat Flour             1
    Bulgur Wheat Flour             1
    Parboiled Rice                 3

In addition to the above, several plants in each category were contacted
by telephone  for  information  on  the  industry  and  waste  handling.
Detailed data were obtained during these conversations consisting of raw
material description, flow rates, waste quantities, and waste treatment.

Plant  sampling  of each industry subcategory was provided at a total of
eight plants with emphasis focused on plants having typical waste  loads
and  waste  treatment facilities.  The sampling program provided data on
the raw and treated waste streams.  It  also  provided  verification  of
data on waste water characteristics  provided by the plants.

    Industry                Total Plants^ Sampled

    corn Wet Milling                4
    Corn Dry Milling                1
    Bulgur Milling                  1
    Parboiled Rice Milling          2


GENERAL DESCRIPTION OF THE INDUSTRY

The  cultivation,  harvesting,  and  milling of grains dates back to the
beginning cf recorded history.  Wheat  was  first  cultivated  in  Asia,
later  became  prominent  in  Europe,  and  was introduced to the United
States by the colonists in the early 1600's.  Similarly, rice originated
in Asia thousands of years ago and was brought to this  country  in  the
mid  1600's.   Corn  or  maize is the only one of the three major cereal
grains that is indigenous to this country, and  was  cultivated  by  the
Indians long before Columbus discovered America.

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The  cereal  arains, sc-called because they can be used as food, inclule
barley, corn, grain sorghum, millet, oats, rice, rye, and  wh^at.   This
report,  however, only covers the milling of the three principal grains,
namely, corn, wheat, and rice.

Corn

With an annual agricultural yield of about 140 million metric tons   (5.5
billion  bushels),  the United States is easily the largest corn producer
in the world.  About 80 percent of the corn crop is used as animal feed,
as shown in the accompanying table.  Some eight percent of the  corn  is
milled  into  various products and the remainder of the crop is used for
table and breakfast foods, alcohol, and other industrial products or  is
exported.


                                Table 1

                Uses of Corn Grown in the United states

                          Percent of total corn_prQduction

    Feed                               77.3
    Export                             14.0
    Wet milling                         5.7
    Dry milling                         2.2
    Alcohol                             0.8
    Seed                                0.3
    Breakfast food                       0.2

Corn  is  milled  by  either  dry  or  wet processes, and the production
methods and final products of each are distinctly different.   Corn  dry
milling  produces meal, grits, and flour while the principal products of
corn wet rrilling are starch, oil, syrup, and dextrose.

Corn_Wet_Millin2-

The corn wet trilling industry is an American development and  originated
with  the  commercial  extraction of starch from corn in 1842, at a time
when the greatest source of starch was from wheat and potatoes.   Starch
from  the  corn  wet  trilling process now accounts for 95 percent of the
American starch output.

The first corn wet  mills were  segregated  to  produce  either  finished
starch  or corn syrup.   Not until the turn of the century was a combined
mill developed to produce both starch and syrup.  Many  of  the  present
milling  companies  had their beginning at about this time as most of the
existing milling plants were consolidated.

Today, twelve companies operate 17 plants in seven states with  a  total
corn  grind  cf  over  seven  million  metric tons per year (275 million
bushels per year).   A list of the companies and plants is given in Table
3.  Of these plants, eight were put into operation since 1949, utilizing

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newly developed equipment and methods of  operation  -to   provide   better
products,  higher  yields,  and less waste.  The older plants  meanwhile,
have  incorporated  new  process  procedures  and  replaced  nearly  all
equipment  with  more  efficient  machinery  providinq cleaner operating
conditions and increased yields with reduced odors,  wastes,   and   water
usaqe.  The raw material for corn wet millinq is the whole kernel.   Most
of  the qrain, primarily hybrid yellow dent corn, comes  from the midwest
or Corn Belt reqion of the country.  The composition of  yellow dent corn
is qiven in Table 2.

                                Table 2

             Composition by Dry Weiqht of Yellow Dent Corn

                                   Percent
         Carbohydrates
         Protein
         Oil
         Fiber
         Ash
80
10
 U.5
 3.5
 2.0
The standard unit of measure cf corn in the United  States  is  the  tushel
(25.1  kq)  and  plant size is measured by the number  of bushels of corn
processed per day.  Wet millinq plants receive the  corn kernels  at 10 to
25 percent moisture.  The standard bushel is defined,  for purposes  of
this  repcrt, as 25.4 kq  (56 Ibs) corn at 15.5 percent moisture.  The 17
corn wet mills in this country ranqe in size  from   about   380   to  3050
kkq/day  (15,000 to  120,000 SBu/day).
       CORN <

STEEPING

k.
f
CORN OIL
EXPELLING
AND REFINING
1
WE
SE
4-
STEEPWATER
>



GERM
IT MILLING
D STARCH
.PAR AT ION
HULLS
GLUTEN
r
FEED
DRYING
^ CORN OIL
WATER
+
STARCH

STA
MODI

^ANIMAL ™
T FEED
BCH
ING,
FYING

~M<
SYRUP
HYDROLYSIS
AND REFINING
               REGULAR AND
              MODIFIED STARCHES
                                                        CORN SYRUP
                                                       ' & DEXTROSE
                             CORN WET MILLING
The   corn  wet  milling  can  be  considered   as   three  basic  process
operations, namely millinq,  starch production  and  syrup manufacturinq as
shown in the accompanying schematic  diagram.   The   initial  wet  millinq
                                10

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sequence  separates the basic components of the corn kernel into starch,
germ, gluten, and  hull.   The  individual  process  operations  include
steepinq,  grinding,  washing, screening, centrifugation, and flotation.
Following the basic  milling  and  separation  operations,  the  product
slurry may be dried, modified and then dried, or converted +:o corn syrun
or  dextrose.   In  processing  the  starch  slurry from the wet mill inn
operations, the fractions are proportioned between the starch  finishim
and  corn  sweeteners  departments.  The supply of starch distributed to
each will depend on daily and seasonal fluctuations  controlled  by  ~h"
economic  situation  and,  ultimately,  customer demand and competition.
Products from the dry starch operations may  be  classified  as  regular
(unmodified)   and  modified starches.  The purpose of modification is *:o
change the resultant starch characteristics to conform to  the  specific
needs  of  the  industry  using  the  product.  Starch modifications are
accomplished, generally, by chemically treating the  raw  starch  slurry
under  closely controlled conditions.  In the corn sweetener department,
the starch slurry is hydrolyzed to corn syrup and dextrose.

The finished products of starch and corn sweeteners resulting  from  the
corn  wet  milling process, as well as the secondary products, have many
uses in the home and industry.  A portion of the finished  products  are
used  directly in the home, but the bulk of the products are distributed
among industrial users.  Food products account for 1/U  to  1/3  of  th<~-
total starch and starch converted products.  The list of industrial uses
includes,   in  descending  order  of  quantity:  paper  products,  food
products, textile  manufacturing,  building  materials,  laundries,  and
other miscellaneous applications.

Corn Dry Milling-

Ccrn dry milling differs in almost all respects from wet milling, except
in  the raw material used.  The grinding or dry milling of corn oredat^^
wet milling by hundreds of years.  Today, a little over two  percent  of
the total ccrn production is processed by the dry millers.

There  are  approximately  126  corn  dry  mills throughout the country,
although most are located in the midwestern Corn Belt, ranging  in  siz-
from  very  small  millstone operations to large modern mills with capa-
cities up to about 1500 to 1775 kkq/day  (60,000 to 70,000 SBu/day.)  The
larger  plants  process  about 90 percent of the corn in the dry milling
segment of the industry.

Most small millers are distinguished from  the  larger  plants  in  both
production methods and finished products.  Specifically, the small mills
usually  grind the whole kernel and produce only ground whole corn meal.
These small mills use little, if any, water and will  not  he  discussed
further in this report.

The  larger  irills  employ  a  number  of  production  steps designed to
separate the various fractions of the corn, namely the endosperm,  bran,
and germ.  The primary oroduction sequence is shown on thu-

-------
                                Table 3
                 Corn Wet Milling Companies and Plants
American Maize-Products Company
250 Park Avenue
New York, New York  10017
  Plant:  Hammond, Indiana  46326

Anheuser-Busch, Inc.
P.O. Box 1810 Bechtold station
St. Louis, Missouri  63118
  Plant:  Lafayette, Indiana  47902

Cargill, Inc.
Cargill Building
Minneapolis, Minnesota  55402
  Plants:  Dayton, Ohio  45414
           Cedar Rapids, Iowa  52401

Clinton Ccrn Processing Company
Division of Standard Brands, Inc.
Clinton, Iowa  52732
  Plant:  Clinton, Iowa  52732

Corn Sweeteners, Inc.
P.O. Box 1445
Cedar Rapids, Iowa  52406
  Plant: Cedar Rapids, Iowa 52406

CPC International Inc.
International Plaza
Englewood Cliffs, New Jersey  07632
Plants:  Argo, Illinois  60501
         Pekin, Illinois  61555
         North Kansas City, Missouri

         Corpus Christi, Texas  78048
Dimmitt Corn Division
Amstar Corporation
Dimmitt, Texas  79027
  Plant:  Dimmitt, Texas
    79027

Grain Processing Corporation
Muscatine, Iowa
  Plant:  Muscatine, Iowa  52761
The Hubinger Company
Keokuk, Iowa  52632
  Plant:  Keokuk, Iowa
52632
National Starch and Chemical
  Corporation
750 Third Avenue
New York, New York  10017
  Plant:  Indianapolis
          Indiana 46206

Penick and Ford, Limited
(Subsidiary of VWR United
  Corporation)
Cedar Rapids, Iowa  52406
  Plant:  Cedar Rapids, Iowa

A. E. Staley Manufacturing
  Company
Decatur, Illinois  62525
  Plants:  Decatur, Illinois
           62525
           Morrisville, Penn-
           sylvania  19067

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accompanying  diagram.  The corn is first cleaned  and then  tempered  to  a
moisture content of about 21 percent.  The germ and  bran  are   separated
from  the  endosperm  in a series of grinding/ sifting, classifying,  and
aspirating operations.  In an additional step, corn  oil is   mechanically
extracted  from the germ.  The final products of a typical  corn dry  mill
include corn meal, grits, flour, oil, and animal feed.
                  WATER
                             WATER
         CORN-
DRYING,
T F SIFTING
BRAN I GERM
ANIMAL
FEED
I CORN MEAL,
~ GRITS, FLOUR
^ OIL
T EXTRACTION
1 SPENT
1 GERM
ANIMAL
FEED
w CORN
r OIL
                            CORN DRY MILLING
Wheat
Wheat production is now the largest of any cereal grain   in   the   world.
The  United  States  produces  about 38 million metric tons  (1.5  billion
bushels) and is second only to Russia  in  total  production.   In  this
country,  about  40  percent  of  the wheat is milled into flour  and the
remainder is used for breakfast foods, macaroni products,  animal  feed,
alcohol production, and ether more limited markets.

The milling of wheat in the United States is handled by  over  two  hundred
plants  of  various sizes and ages, scattered across the country.   There
are several types of wheat and various grades of each type available  to
the  wheat miller.  In some mills, other grains are milled using  similar
operations.  Different kinds of wheat or regulated blends of  wheat  are
mixed at the mills, together with various additives.  These products are
formulated to customer specifications to meet the required qualities for
final use.

Preparation   of  wheat  into  ground  flour  or  granular  products  is
fundamentally a dry milling process.  Other similar grains such   as  rye
and  durum,  not  detailed  separately  in  this  report,  are milled by
comparable processes.  Some variations may  be  found  in  the  cleaning
process  and  in  the  milling and separation based on the prime  product
requirements.

Wheat milling, shown below, begins with cleaning with water or air.   The
wheat is then tempered to about 17 percent moisture and  milled in roller
mills.  The germ and bran are separated from the flour by sifting.
                                 WATER
             WHEAT •
STORAGE
CLEANING
k
f



k
f
MILLING &
SIFTING
IGERM
[BRAN
                                                     FLOUR
                                           MILLFEED
                               WHEAT MILLING


                                    13

-------
A special process of particular  significance  to   this   study,   is  the
production of bulgur shown in the next diagram.  Bulgur  is  wheat that is
parboiled,  dried,  and partially debranned  for  use in either  cracked or
whole  grain  form.   Bulgur  is  produced   primarily  for   the   Federal
Government  as  part  of  a national effort  to utilize surplus wheat for
domestic use and for distribution to underdeveloped countries  as part of
the Foods for Peace program.   There  are  five  bulgur   mills  in  this
country  ranging  in  size  from  about 145  to 408  kkg/day  (3200 to 9000
cwt/day).  The companies, plant locations, and estimated capacities  are
given in Table 4.
                           WATER
       WHEAT
                                                           BULGUR
                                                MILLFEED
                            BULGUR PRODUCTION
                                Table  4

           Bulgur Mills - Locations  and  Estimated Capacities
Archer Daniels Midland Co.
Shawnee Mission, Kansas   66207
  Plant:  Abilene, Kansas

Burrus Mills Division
  Cargill, Inc.
Dallas, Texas  75221
  Plant:  Dallas, Texas

California Milling Corporation
Los Angeles, California   90058
  Plant:  Los Angeles, California

Fisher Mills, Inc.
Seattle, Washington   98134
  Plant:  Seattle, Washington

Lauhoff Grain Company
Danville, Illinois   61832
  Plant:  Crete, Nebraska
227
145
5000
3200
204
408
272
4500
9000
6000
                                   14

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Pice

The  unique  nutritional  and  chemical  qualities of rice makes it one of
the world's most important  food  products.   In the United States,  i-t-  is
used  in  numerous  products   and  in  many  forms including (in descendinq
order) :

         Direct table food
         Brewing
         Breakfast cereals
         Soups, canned foods,  baby foods
         Crackers, candy bars, and others

Production of rice is scattered  throughout the world with  the  greatest
crop concentration in Asia  and nearby island areas.  Although; the United
States  produces  only  a   small percentage of the total crop, it is the
world's largest exporter.   The cultivation of rice in the United  States
began  around  1635 in South Carolina.  Rice is now produced in thirteen
states with an annual grain production  over 3.8 million metric  tons  in
1972  (8.5  billion pounds).   Texas,  Arkansas, Louisiana, and California
produce 97 percent of this  total.   There has been a gradual  decline  in
the  number of rice companies, and a  corresponding decline in the number
of mills operated.  In 1973 there  were  36  companies in the United States
operating 42 rrills.

Milling of rice differs from ether cereal  milling in that the product is
the whole grain rather than flour  or  meal.  The milling sequence,  shown
in  the accompanying diagram,  begins  with  the cleaning of the rough rice
and removing the inedible hulls  by passing the  grain  through  shelling
devices  or  hullers.   Aspirators then separate the loosened hulls from
the resultant brown rice which,  in turn, is milled to remove the  coarse
outer  layers of bran and germ using  machines called pearlers.  The bran
and germ are separated from the  milled  rice and  the  final  white  rice
product  is  sized,  enriched  with vitamins and minerals, and packaqed.
Fice hulls, bran, polish, and  small pieces of the grain may be sold sep-
arately or combined into so-called millfeed for  animals.   The  average
yields for ordinary rice milling are:

                                        Percent

         Whole grain white  rice             54
         Broken grain rice                  16
         Hulls and waste                    20
         Bran                                8
         Rice polish                         2

                                              VITAMIN
                                              MINERALS
            RICE—M CLEANING I—M MILLING
SEPARATION	-l-k WH°LE GRAIN RICE
                                        JBRAN
                                        GERM
                                       RICE POLISH
                                                   BROKEN GRAIN RICE
                                  MILLFEED
                               ORDINARY RICE MILLING
                                   15

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Parboiling  rice  has  been practiced  in  foreign  countries for years and
differs significantly from ordinary  rice   milling.    The  manufacturing
process  was introduced in the United  States  in 19UO.   At present, there
are six known parboiled rice plants in this country,  as given  in  Table
5,  four  in Texas, one in Arkansas, and  one  in California.  The purpose
of parboiling rice is to force some of the  vitamins   and  minerals  from
the  bran  into  the  endosperm.   The product also  has superior cooking
qualities and is more impervious to insect  damage in storage.

                                Table  5

                    Parboiled Rice Milling  companies
Blue Ribbon Rice Mills, Inc.
Box 2587
Huston, Texas  77001

Comet Rice Mills, Inc.
Box 1681
Houston, Texas  77001

P&S Rice Mills, Inc.
Box 55040
Houston, Texas  77055
Rice Growers Association of California
111 Sutter Street
San Francisco, California  9410U
  Plant:  Sacramento, California

Riceland Foods
Box 927
Stuttgart, Arkansas  72160

Uncle Ben's, Inc.
Box 1752
Houston, Texas  77001
The manufacturing process, shown below,  begins with careful clean-
ing of the rice.  The rice is then  parboiled  by soaking in water
and cooking to gelatinize the starch.   Procedures for soaking and
ccoking are carefully controlled to produce suitable product pro^-
perties and yields.  After cooking,  the  water is drained and the
parboiled rice is dried before milling  in  the same manner employed
for ordinary rice milling.
        RICE
                           WATER
                                                   VITAMIN
                                                  MINERALS
CLEANING
k
T
PARBOILING

k
w


k
w
WACTFV^TFR "'»!
-------
PRODUCTION PROCESSES


The production  methods  used  in  milling  the  various  grains  differ
significantly  in most cases as summarized earlier in this section.  ^h0
following discussion provides  a  more  detailed  description  for  each
industry subcategory of the processes used in milling.

Corn_Wet_Milling

Storage_and_Cleaning-

Corn  wet  milling,  shown  in Figure 1, begins with the delivery to the
plant of shelled corn, normally No. 3 grade or better.  The corn is  dry
cleaned  to  remove  foreign materials, stored, and dry cleaned a second
time prior to entering the main production sequence.
Steeping, the first step  in  the  process,  conditions  the  grain  for
subsequent  milling  and  recovery  of  corn constituents.  This process
softens the kernel for milling, helps break down the protein holding the
starch particles, and removes certain soluble constituents.

The steeping process consists of a series of tanks, usually referred  to
as steeps, and might be termed a batch-continuous operation.  Each steeo
holds about 51 to 152 kkg (2000 to 6000 SBu) of corn, which is submerged
in  continuously  recirculating  hot water  (about 50 degrees C).  Sulfur
dioxide in the form of sulfurous acid is added to the incoming water  to
aid in the steeping process.

As  a  fully-steeped  tank of corn is discharged for further processing,
fresh corn is added to that steep tank.  Incoming  water  to  the  total
steeping system is derived from recycled waters from other operations at
the mill, and is first introduced into the tank with the oldest corn (in
terms  of  steep  time)  and  passes through the series of steeps to the
newest batch cf corn.  Total steeping time ranges frcm 28 to 48 hours.

Steep_water_Eva£or at ion-

Water drained from the newest corn steep is discharged to evaporators as
so-called light steepwater containing about six percent of the  original
dry  weight  of  the  grain.   On  a dry weight basis, the solids in the
steepwater contain 35 to  15  percent  protein  and  are  recovered  for
addition  to  feeds.   Such  recovery  is  effected by concentrating the
steepwater to 30 to 55 percent solids in triple effect evaporators.  The
resulting steeping liquor, or heavy steepwater, is usually added to  the
fibrous  milling  residue which is sold as animal feed.  Some steepwater
may also be sold for use as a nutrient in fermentation processes.

Milling-

The steeped ccrn then passes through degerminating mills which tear  the
kernel  apart  to free the germ and about half of the starch and gluten.
The resultant pulpy  material  is  pumped  through  liquid  cyclones  or
flotation  separators  to  extract  the  germ  from the mixture of pulp,
                                 17

-------
                            SHELLED CORN
                                  STORAGE  AND
                                    CLEAING
                ST EEPW ATER
       ST EEPW ATER
      E V APORAT ORS
 STEEPWATER
CONCENTRATES
                       HULL
                      GLUTEN
      FEED DRIERS
          FEEDS
                                STEEP TANKS
                                DEGERMINATORS
                                GERM SEPARATORS
                                GRINDING MILLS
                                WASHING SCREENS
                                   CENTRIFUGAL
                                   SEPARATORS
                                   STARCH
                                 WASHING MIHIS
                          1
                          I
                          I
                     I	l	1
                     !   STARCH
                    "* MODIFYING J
       STARCH DRIERS
                                    CORN SYRUP
DRY STARCHES
                     DEXTRIN
                      ROASTERS
                  D E X T R I N S
                                                 GERM
                                                                  *
                WASHING S ORfINC
                  OF URMS
                                                                 OIL EXTRACTORS
SYRUP & SUGAR
(ON V! R10R5
1
R E F 1 N
N G
DRUM or SPRAY
   DRIERS
  SUGAR
CRVSTAIUHRS
                                                CORN SYRUP SOUDS
                                                                  CENTRIFUGALS
                                                                   DEXTROSE
                                  FIGURE  1
                     THE CORN WET MILLING  PROCESS
                                     18

-------
starch and gluten.  The germ is subsequently washed,  dewatered,  dri^d,
the oil extracted, and the spent germ then sold as ccrn oil meal.

The  product  slurry  passes  through a series of washing, grinding, and
screening operations to separate the starch and gluten from the  fibrous
material.   The  hulls  are  discharged to the feed house where they are
dried and used in animal feeds.

At this point, the main product  stream  contains  starch,  gluten,  and
soluble  organic  materials.  The lower density gluten is then separated
from the starch by centrif ugation, generally  in  two  stages.   A  hiah
quality  gluten  of  60  to  70  percent  protein and 1.0 to 1.5 percent
solids, is then centrif uged, dewatered, dried, and added to  the  animal
feed.   The  centrifuge underflow containing the starch passes to starch
washing filters to remove any residual gluten and solubles.

Starch_Producti.on-

The pure starch slurry can now be  directed  into  one  of  three  basic
finishing operations, namely ordinary dry starch, modified starches, and
corn  syrup  and sugar.  In the production of ordinary pearl starch, th-
starch slurry is dewatered using vacuum filters or  basket  centrifuges.
The  discharged  starch  cake has a moisture content of 35 to <42 percent
and is further thermally dewatered by one of several different types  of
dryers.   The  dry  starch  is  then  packaged  or shipped in bulk, or a
portion may be used to make dextrin.

Modified starches are manufactured for various food and trade industries
for special uses for which unmodified starches are  not  suitable.   For
example,  large  quantities of modified starches gc into the manufacture
of paper products, serving as  binding  for  the  fiber.   Modifying  is
accomplished  by treating the starch slurry with selected chemicals such
as hydrochloric acid to produce  acid-modified,  sodium  hypoclorite  to
produce  oxidized,  and ethylene oxide to produce hydroxyethyl starches.
The treated starch is then washed, dried, and packaged for distribution.
Since most chemical treatments result in a more water  soluble  product,
waste  waters  from the washing of modified starches may contain a large
concentration of BOD_5.  In addition, because of the presence of residual
chemicals, and dissolved organic materials,  these  waste  waters  often
cannot be reused and must be discharged to the sewer.
In  most  corn wet mills, about 40 to 70 percent of the starch slurry is
diverted to the corn syrup and sugar finishing department.   Syrups  and
sugars   are  formed  by  hydrolyzing  the  starch,  partial  hydrolysis
resulting in corn syrup and complete hydrolysis  producing  corn  sugar.
The  hydrolysis step can be accomplished using mineral acids or enzymes,
or a combination of both.  The hydrolyzed product  is  then  refined,  a
process  which  consists  of  decolorization  with  activated carbon and
removal of inorganic salt impurities  with  ion  exchange  resins.   The
refined  syrup  is  concentrated to the desired level in evaporators and
ccoled for storage and shipping.
                                19

-------
The production of dextrose is quite similar to that of corn  syrup,  the
major  difference  being that the hydrolysis process is allowed to go to
completion.  The hydrolyzed liquor is refined with activated carbon  and
ion exchange resins to remove color and inorganic salts, and the product
stream  is  concentrated  to  the  70  to  75  percent  solids  range by
evaporation.  After cooling, the liquor is transferred to  crystallizing
vessels  where  it  is seeded with sugar crystals from a previous batch.
The solution is held for several days while  the  contents  are  further
cooled  and  the  dextrose  crystallizes.  After about 60 percent of the
dextrose sclids have crystallized, they are removed from the  liquid  by
centrifuges,  dried,  and packed for shipment.  A smaller portion of the
syrup refinery is devoted to the production of corn  syrup  solids.   In
this  operation,  refined  corn syrup is drum or spray-dried to generate
corn syrup solids, which are somewhat more convenient to  use  than  the
liquid syrup.
The  corn dry milling process is shown in Figure 2 and begins with Grade-
No. 2 or better shelled corn as the raw material.  After  dry  cleaning,
some  mills  wash  the  corn to remove any remaining mold.  Waste waters
from the washing operation normally go to  mechanical  solids  recovery,
using  dewatering  screens  or  settling  tanks.   The  solids from this
operation are added to the hominy feed  and  the  spent  wash  water  is
discharged frcm the plant.

Tempering,  the  first process operation, raises the moisture content of
the corn tc the 21 to 25 percent level necessary for milling.  The  corn
passes  through  a degerminatcr that releases the hull and germ from the
endosperm and the product stream is dried and cooled in preparation  for
f ractionation.

Fractionaticn  comprises  a series of roller mills, sifters, aspirators,
and separators.  The product  stream  first  passes  through  corrugated
roller  mills  or  break rolls and then to sifters.  This process may be
repeated several times and, after the separation of the germ and  hulls,
the  fine  product stream goes to reduction mills to produce corn flour.
Corn grits and meal are removed earlier in the  fractionating  sequence.
The separated germ goes to oil expelling operations, where approximately
10.7  to  1U.3 kg/kkg (0.6 to 0.8 Ibs/SBu) of oil are recovered from the
ccrn.

A few of the larger mills further process the  grits,  meal,  and  flour
through  expanders and/or extruders.  Such processing is not an integral
part of the basic milling sequence and is not practiced  by  most  small
and mediurr sized mills.

Wheat, Milling

Wheat  milling  has  been  subdivided  into  two  segments, normal flour
milling and bulgur  production.   The  production  methods  differ  con-
siderably and are discussed separately in the following paragraphs.
                                 20

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                                        CORN

^

r
WASHING &
DE WATER ING
'
RECEIVING
STORAGE &
DRY CLEANING


1
TEMPERING

SOLIDS
RECOVERY
^
. I
          WASTEWATER
 SOLIDS
TO FEED
                                      DEGERMING
                                       DRYING &
                                       COOLING
                     HULLS
MILLFEED
                             GERM
                OIL EXPELLING
                & EXTRACTING
                  CORN OIL
                MILLING &
                SIFTING
 I    l COP
J    '  4
CORN GRITS
    MEAL
               REDUCTION
                MILLING
              CORN FLOUR
                               FIGURE 2

                    THE  DRY CORN MILLING PROCESS
                             21

-------
N o r ma 1_F 1 g ur _M i 1 1 i ng -

The  wheat  milling  process,  presented  in  Figure 3f starts vvith dry,
matured, graded, sound,  and  partly  cleaned  wheat  seed.   Grain,  as
needed,  is  moved from storage to the cleaning house for final cleaning
prior to milling.  It is here that  other  seeds,  grains,  arid  foreign
matter  such  as  sticks,  stones,  and  dust  are removed.  The type of
equipment and sequence of steps in the cleaning operation,  as  well  as
the  extent  of  cleaning,  may vary between mills.  As a final cleaning
step, a few mills use a water wash following  air  cleaning.   The  wash
adds about one percent moisture to the original wheat and is believed to
reduce  microbiological  contaminants.  The excess water from washing is
removed by centrifugal force.  Prior to grinding, the wheat is  tempered
and conditioned by adding water under carefully controlled conditions to
bring  the  moisture  content  up  to  desired  levels, usually 15 to 20
percent.  The amount and method  of  moisture  addition,  soaking  time,
temperature,  and  conditioning  time  will vary for different grades of
grains and individual rrill procedures.

After tempering, the wheat is  ready  for  milling,  which  is  normally
performed  in  two  sets  of  operations.   The  first, or break system,
comprises a series of corrugated rolls, sifters,  and  purifiers.   This
milling  operation  breaks  open  the  bran.   The mixture of free bran,
endosperm, germ, and bran  with  adhering  endosperm  are  scalped  over
sifters.   The  scalped  fractions  of  endosperm  go into purifiers for
separation and grading.

The second, or reduction, system consists of a series of  smooth  roller
mills to reduce the granular middlings  (endosperm) from the first system
to  flour.   After each reduction, the product is sifted to separate the
finished flour, germ, and the unground endosperm.  The  latter  is  sent
back  to  reduction  rclls  for  further  processing.  At the end of the
milling operation, the discharged flour  is  treated  with  a  bleaching
agent  to mature the flour and neutralize the color.  Depending upon its
end use, the flour may be blended or enriched.  It is then directed into
storage hoppers prior to packaging or bulk shipping.

Millers may vary the milling procedures  used  in  the  different  steps
described above.  Flour emerges at several points in the process and may
be kept separate or the various streams combined.  The products from the
individual  mills  differ  in  type and quantity of flour produced.  By-
products from the milling industry consist primarily of the wheat  germ,
shorts,   bran,  and  unrecovered  flour.   These  byproducts,  know  as
millfeed, are generally used as animal and poultry feed additives.
Of the various processes in the manufacture of bulgur, the most familiar
is a continuous mechanized system which is herein described and shown in
Figure 4.  As a first step, the wheat is thoroughly cleaned  and  graded
by  conventional  cleaning  processes  to  remove  loose dust, dirt, and
chaff.  The wheat  enters  a  washer  which  also  raises  the  moisture
content.  From the washer, the wheat is conveyed to the top of the first
                                  22

-------
WATER
     WASTEWATER
      MILLFEED
                                    WHEAT
 RECEIVING
 STORAGE &
DRY CLEANING
EAT
4ING
L
1 |

r^
TEMPERING

                                   BREAKER
                         BRAN
                                    SIFTER
                                      I
                                   PURIFIER
                                   REDUCING
                                    ROLL
                         GERM
                                    SIFTER
                ADDITIVES
                                  BLEACHING &
                                  ENRICHING
                                    FLOUR
                                                  WATER
                                                 STEAM
                                   FIGURE 3

                         THE  WHEAT  MILLING  PROCESS
                              23

-------
                          WHEAT
                        RECEIVING
                        STORAGE &
                       DRY CLEANING
     WATER

WASTEWATER <

     WATER
     STEAM


     STEAM
               BRAN
MILLFEED
                         WASHING
                         SOAKING
                         PRESSURE
                         COOKING
                          DRYING
                         COOLING
                         POLISHER
                         GRINDING
                          SIFTING
                        ENRICHING
                       & BLENDING
                      BULGUR  WHEAT
                         FIGURE 4
                    THE BULGUR PROCESS
                                          MEAL & FLOUR
                        24

-------
of  a series of soaking or tempering bins where the grain is conditioned
as it progresses continuously through each bin from top entry to  bottom
of  discharge.  Water and live steam are added to the grain between each
bin as it travels along a transfer conveyor from the bottom of the first
bin to the top of the second.  The process is repeated for the next  bin
with  a  progressively  higher  moisture content and temperature.  Time,
percent moisture,  and  temperature  are  all  important  variables  and
require clcse control during this soaking sequence.

Upon  leaving  the  bottom of the last tempering bin, the wheat enters a
pressurized steam cooker where the starch in the kernel is  gelatinized.
The cooked wheat is discharged to a series of two continuous dryers, the
first  for  the removal of surface moisture and the second to reduce the
moisture content to 10 to 11 percent.

Variations to  the  general  procedures  outlined  above  occur  between
manufacturing plants.  Conventional grain milling procedures, similar to
those  used  in  normal  flour production, follow the drying operations.
The dried wheat is conveyed to a polisher (pearler or  huller)   follcwed
by  a  series of grinders and sifters, which separate the fines and bran
from the granular finished product.  The combined by-products,  approxi-
mately  10  percent of the raw materials, are disposed of as animal feed
while the bulgur is packed in 100 Ib bags for shipment.

Rice_Millin2

The raw material for rice milling may be one  of  several  varieties  of
rice, which are normally classified as long grain  (such as Bluebelle and
Bluebonnet), medium grain (such as Nato and Nava) , and short grain  (such
as  Pearl).   Each  variety  is  graded according to U.S.  Department of
Agriculture  standards.   In  this  country,  the  long  grain  rice  is
preferred.

Normal  rice  milling is a dry process operation and is described herein
only to contrast it with parboiled rice production.  The latter  adds  a
cooking or parboiling step ahead of the conventional milling sequence.

Norma1_Rice_Mi11ing-

The production operations, shown in Figure 5, begin with the cleaning of
the  rough  rice.   Shaker  screens  and  aspirators  are used to remove
foreign materials, hulls, and chaff.  The cleaned rice is then  dehulled
in  roller  shellers  or  hullers  with  the  loosened  hulls removed by
aspirators.  Rough rice that is not dehulled is separated from the brown
rice in a paddy machine, or separator, and returned to a second  set  of
shellers.

At  this  point,  brown  rice  may  be  removed as a finished product or
processed through the complete milling operation.   Calcium carbonate  is
added  as  an abrasive to help in removing the bran from the rice in the
pearlers.  In some cases, water is added to the brown rice to aid in the
removal of tightly adhering bran layers and improve the adhesion of  the
calcium  salt  to the kernel.  The pearlers remove most of the bran with
                              25

-------
                     ROUGH RICE
                                               DRAFT
                      RECEIVING
                      STORAGE &
                    DRY CLEANING
                       SHELLER
HULLS
BRAN &
RICE POLISH
BRAN
r VITAMIN
SEPARATOR
1
1
PEARLER 1
|
BRUSH
S& 1
TO MILLFEED   MINERALS
              ADDITION
                       TRUMBLE
                                        BROWN RICE


                                        RICE  POLISH
                                        TO MILLFEED
                                   SCREENINGS
                                 SECOND HEADS
                       SCREEN &
                      SEPARATOR
RICE FLOUR
  MILLING
                      WHITE RICE
RICE FLOUR
                        FIGURE  5

                THE RICE  MILLING  PROCESS
                           26

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some kernel breakage occuring.  Some plants use pearlers in parallel  as
a  one-break  operation  while  some  have twoand three-break systems to
reduce breakage.  Air through the pearlers removes the loose bran  to  a
central  bran  bin  and  also  cools  the  rice to reduce stress cracks.
Additional processing in a brush machine  removes  the  remaining  loose
bran.

Rotating horizontal drum trumbles are used to polish the rice.  The rice
is  coated in the trumbles with talc and water, or glucose water, to fix
the remaining bran to the kernels, which are then dried with warm air to
produce the desired luster.  Rice enriching is  accomplished  by  adding
vitamins  and  minerals,  along  with  water,  ahead  of  the  trumbles.
Finally, the whole and broken rice kernels are separated to meet product
standards.

Farboiled^JRice-

Parboiled rice production begins with basic rice cleaning in shakers and
aspirators.  Precision graders are added in parboiled rice  cleaning  to
remove  the immature small grains and the rice that has been dehulled in
handling.

The parboiling process, as presented in Figure 6,  may  involve  several
variations,  only  one of which is discussed in this report.  A measured
amount of cleaned rough rice is dumped into the  steeping  tanks,  which
are  then  sealed.  A vacuum is applied to remove most of the air in the
hulls and the voids to allow water to penetrate into the kernel  faster.
Hct  water (70 to 95 degrees C)  containing sodium bisulfite as a bleach-
ing agent is added to cover the rice and  the  tank  is  pressurized  to
about  7.8  atm.  The water is heated and recirculated to maintain close
temperature control.  When the grain moisture content reaches  about  32
percent,  the  tank  is drained and the rice is discharged into a cooker
heated with live steam to gelatinize the starch.  The parboiled rice  is
then dried and cooled before milling.

Besides  steeping  water  discharge,  waste waters may be generated from
barometric condensers en the dryer vacuum system and from wet  scrubbers
on the other dryers.  Steepwater is not reusable for steeping because of
the color pick-up, which would discolor the rice.

In  parboiled rice milling, machines called whiteners are used in series
with pearlers to loosen the bran.  Otherwise,  the  milling  process  is
essentially the same as for normal rice.


WASTE WATER CONSIDERATIONS IN INDUSTRY

Of  the four subcategories of grain milling covered in this report, only
corn wet milling generated large quantities of waste waters.  Water  use
in  the  corn wet mills ranges from about 3785 to 189,000 cu m/day (1 to
50 mgd) .  Large quantities of BOD5_ and suspended solids  are  discharged
in the waste water, and hence, waste waters from these mills potentially
constitute  major  sources  of pollution.  At the present time, only six
                              27

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  HOT WATER
                     ROUGH RICE
                     RECEIVING
                     STORAGE
                   DRY  CLEANING
                        X
 STEEP
 TANKS
                                     • WASTE WATER
     STEAM
                      COOKER
                       DRYER
                      COOLER
          HULLS
        BRAN  &
      RICE POLISH
TO MILLFEED
 SHELLER
WHITENER
 PEARLER
  BRUSH
                      TRUMBLE
                      SCREEN &
                     SEPARATOR
                  PARBOILED  RICE



                      FIGURE  6

          THE PARBOILED  RICE  PROCESS
                        28

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corn wet mills discharge directly to receiving waters.  Three  of  these
provide biological treatment, one is constructing a treatment plant, and
the  fifth  will  be  discharging  to  a  new municipal system now under
construction.   The  sixth  discharges  only   once-through   barometric
condenser water.  The remainder discharge untreated or, in at least four
cases,   pretreated   waste   waters  to  existing  municipal  treatment
facilities.

There are two potential sources of waste waters  from  corn  dry  mills,
namely  corn  washing and car washing.  Corn washing has been a standard
operation at many, but not all, mills while  car  washing  is  practiced
infrequently and only at some mills.  The quantities of waste waters are
relatively  small, compared to corn wet mills, ranging up to perhaps 900
cu m/day (2UO,000 gpd), but the wastes  typically  have  high  suspended
solids and BOD_5 concentrations.  Most corn dry mills now discharge their
waste waters to municipal systems.

Ordinary wheat milling usually generates no process waste waters.  A few
mills  wash  the  wheat  and  some infrequently wash cars.  Bulgur mills
produce a small quantity of waste water, 38 to 113 cu m/day  (10,000  to
30,000  gpd) from the soaking and cooking operation.  These waste waters
contain moderately high levels of BOD5 and suspended solids.  All of the
five bulgur mills in the country are believed to discharge these  wastes
to  municipal  systems  for treatment.  Normal rice milling does not use
any process waters, hence no process waste waters.  Parboiled rice  does
generate some waste waters from the parboiling or steeping operation, up
to  about  760  cu  m/day (200,000 gpd).  These waste waters are high in
dissolved BOD, but low in suspended solids.  At least five  of  the  six
rice parboiling plants discharge these wastes to municipal system.
                                 29

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                               SECTION IV

                        INDUSTRY CATEGORIZATION
The  Phase  I  study  of  the  grain milling industry covers the primary
milling of the three principal cereal grains, namely, corn,  wheat,  and
rice.   After  considering  various  factors,  it was concluded that the
industry should  be  categorized  into  several  discrete  segments  for
purposes of developing effluent limitations.  These subcategories are as
follows:
    1.  Corn wet milling
    2.  Corn dry milling
    3.  Normal wheat flour milling
    U.  Bulgur wheat flour milling
    5.  Normal rice milling
    6.  Parboiled rice milling
FACTORS CONSIDERED

The factors considered in developing the above categories included:

    1.   Raw materials
    2.   Finished products
    3.   Production processes or methods
    4.   Size and age of production facilities
    5.   Waste water characteristics
    6.   Treatability of wastes

Careful  examination  of all available information indicated that two of
these factors, specifically  raw  materials  and  production  processes,
provided  a  meaningful  basis  for categorization, as summarized in the
ensuing paragraphs.

Bgff.^ Mater ia Is

Clearly, one basis for  segmenting  the  industry  would  be  the  three
different  raw agricultural products used, specifically corn, wheat, and
rice.  The  three  grains  have  very  distinct  physical  and  chemical
characteristics.    As  described  below,  they also produce distinct raw
waste water characteristics.  Accordingly, raw materials  were  selected
as one basis for  subcategorization.

Finished^Productg

The finished products from the milling of the different grains are quite
distinct.   corn   milling  products  range  from  corn meal and grits to
starch and syrup.  Wheat milling produces flour  for  baking  and  other
purposes  and  the  specialty  product,  bulgur.   Finally, rice milling
                               31

-------
yields ordinary and parboiled rice for direct  human  consumption.   The
wide  variety  of  finished  products,  however,  especially  from  corn
milling,  make  further  segmentation   based   on   finished   products
impractical.   In  a  broad  sense,  the categorization does reflect the
finished products  inasmuch  as  each  subcategory  generates  different
product lines.  The finished products, however, are not themselves basis
for subcategorization.

jProduction_Processes

While  siirilar  in some respects, the production methods used in milling
form an excellent basis for  subcategorizing  the  industry.   The  most
marked  differences  in  production processes are the techniques used in
corn wet trilling.  These highly sophisticated  physical,  chemical,  and
biological   processes   are  completely  different  from  most  process
operations in dry corn, wheat, and rice mills.

Ery corn and ordinary wheat milling employ somewhat  similar  processes.
Both  require cleaning, tempering, milling, and mechanical separation of
the products although slightly  different  equipment  is  used.   Eulqur
wheat  milling  differs  considerably  from  ordinary  flour  milling in
production method, thereby providing a  basis  for  further  subdividing
wheat milling.

Rice milling involves distinctly different techniques and equipment than
ether  grain  milling  operations.   Moreover,  parboiled  rice requires
several  additional  production  steps,   thereby   justifying   further
subdivision  of rice milling into normal rice milling and parboiled rice
production.

Size_and_A3e_of_ProductJ.on_Facilities_

There appears to be little rationale for subcategorization based on size
or age of milling facilities.  Certainly there is no correlation between
large and small mills considering the entire industry as one group.  For
example, a large corn wet mill has nothing in common with a large  rice,
wheat,  or dry corn mill.  Similarly, no relationship can be established
for age of plant for the industry as a whole.

Within  any  of  the  subcategories  defined  previously,  it  must   be
acknowledged  that  relationships  may  exist  between  size  or  age of
production facilities.  However, with the information developed in  this
study no correlations could be established between waste characteristics
and size or age of plants.

Waste_Water_Characteristics

The waste water characteristics from the several types of grain mills do
differ  to some degree,  wet corn mills typically generate large volumes
of wastes containing large total amounts of BOD5 and  suspended  solids,
the  concentrations  of  which  depend on the quantities of once-through
contact cooling waters.
                                32

-------
Corn dry mills discharge much smaller waste water quantities  with  high
EOD5 and suspended solids levels.  Parboiled rice mills generate amounts
of  waste  water  that  are comparable to corn dry mills and with a hiqh
dissolved BODJ5 content.  Suspended solids levels, however, are quitf. low
in  rice  milling  wastes.   Finally,  bulgur  milling  generates  srrall
quantities of moderately strong wastes.

In  summary,  while the waste water characteristics do differ, sometimes
significantly, these differences are adequately reflected by  the  ether
factors mentioned above.

Treat abi].itY_of_Wastes

All  of  the  waste  waters from the grain milling operations covered by
this document are amenable to physical and biological treatment  systems
of  the  same general type.  In general, the fundamental design criteria
will be similar  and  treatability  is  not  a  satisfactory  means  for
subcategorization.
                                33

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                               SECTION V

               WATER USE AND WASTE WATER CHARACTERIZATION

INTRODUCTION

Process  water  use  and  waste  water  discharges  vary markedly ir. the
industry subcategories covered by this document, ranging from  extremely
high uses and discharges in the corn wet milling segment to virtually no
process  waste  waters  in  ordinary flour and rice milling.  Ey far the
largest water users and hence, the greatest waste water dischargers  are
the  corn  wet  mills.  The very nature of corn wet milling processes is
different from other segments of the grain milling industry.  In effect,
these plants are large  chemical  complexes  involving,  as  their  name
implies, wet production methods.

Dry corn and normal wheat milling may employ water to clean the incoming
grain,   although   many  plants,  particularly  the  wheat  mills,  use
mechanical methods  for  grain  cleaning.   Bulgur  and  parboiled  rice
manufacturing  techniques  require  water  for  steeping  or cooking and
hence, generate modest quantities of process waste waters.

This section presents a detailed discussion  of  water  use,  individual
process  and  total  plant waste water characteristics, and factors that
might  influence  the  nature  of  the  waste  waters  generated.    The
information   presented  has  been  collected  from  state  and  federal
regulatory surveys, Corps of Engineers permit  applications,  industrial
sources,  literature,  and the results of a series of sampling visits to
selected plants in each industrial subcategory.  The source of data  are
described in more detail in Section III.  Moreover, the sampling program
provided  limited  information  on  the waste water characteristics from
individual  plant  processes,  particularly  in  the  corn  wet  milling
subcategory.

In  general, information on waste characteristics from cooling water and
boiler blcwdown and water treatment plarvt wastes has been excluded  from
the following discussion.  These auxiliary activities are common to many
industries  and  the  individual practices at any given plant usually do
not reflect conditions that are unigue to the  grain  milling  industry.
The  types  of treatment employed for cooling water systems, boiler feed
water, and process water vary widely throughout the industry and  depend
on such factors as raw water characteristics, availability of surface or
city water, individual company preferences, and other considerations not
related  to  the  basic nature of the industry.  Separate guidelines for
auxiliary wastes common to many industries will be proposed by EPA at  a
later date,


CORN WET MILLING

Water Use
                                 35

-------
For  clarity in presentation, the basic corn wet milling operations have
been divided into three process water and  waste  water  flow  diagrams,
Figures  7, 8, and 9.   These diagrams cover the basic milling operation,
starch production, and syrup refining, respectively.

The modern wet corn mill, in many respects, is already  a  "bottled  up"
plant,  compared  to its ancestors of 50 to 75 years  ago.  Historically,
this segment of the industry has succeeded in reducing the  fresh  water
consumption  per  unit  of  raw  material  used  in the basic production
operations exclusive of cooling  waters.   The  waste  waters  from  one
source  are  now  used  as makeup water for other production operations.
Fresh water, recycled process waste waters, and discharged waste  waters
are  shown  on the attached diagrams.  Recycled process waste waters are
identified by the symbol "PW" to distinguish them frcm waste waters that
are sewered.

Fresh water enters the overall  corn  wet  milling  production  sequence
primarily  in  the  starch  washing  operations.   This water then moves
ccuntercurrent to the product flow direction back through the mill house
to the steepwater evaporators.  More  specifically,  the  process  waste
waters  frcm  starch  washing are reused several times in primary starch
separation, fiber washing, germ washing, milling,  and  finally  as  the
input  water  to  the corn steeping operation.  The principal sources of
waste waters discharged to the sewer from this  sequence  of  operations
are modified starch washing, and condensate from steepwater evaporation.

Additional fresh water is used in the syrup refinery.  Although practice
varies  within  the  industry,  fresh  water may be introduced in starch
treating,  neutralizing,  enzyme  production,  carbon   treatment,   ion
exchange,  dextrose  production,  and  syrup  shipping,  as indicated in
Figure 9.  In some plants, evaporator condensate is used to supply  many
of  these fresh water requirements, particularly in carbon treatment and
ion exchange regeneration.  Other process waste waters are used  in  mud
separation, syrup evaporation, animal feeds, and corn steeping.

Total  water use in this subcategory varies from less than 3785 cu m/day
up to 190,000 cu m/day  (1.0 mgd to 50 mgd) depending, in large  measure,
on  the  types  of  cooling  systems employed.  Those plants using once-
through cooling water have much higher water demands  than  those  using
recirculated  systems, whether they be surface or barometric condensers.
The water use per unit of raw  material  ranges  from  about  0.0067  to
0.0745  cu  m/kkg of corn grind  (45 to 500 gal/MSBu).  Those plants that
predominantly use once-through cooling water will have total  water  use
values  of  about  0.045  cu m/kkg of grind  (300 gal/MSBu).  This number
should be contrasted with  the   several  plants  that  use  recirculated
cooling  water  almost exclusively, where the total water use values are
about 0.0075 cu m/kkg  (50 gal/MSBu).  Information is  not  available  on
the  water  use by individual production processes since these vary from
plant to plant.  Company preferences, type of  equipment,  product  mix,
and  other  factors  all  influence  the  water use in terms of both the
individual processes and the total plant.
                                  36

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Waste_Water^Characteristics_gf Individual Product! on^Processes

As indicated in the preceding discussion  on  water  use,  many  process
waste  waters that were discharged to sewers years ago, are now recycled
back into the process.  This section is concerned only with those wastes
that are generally discharged  to  the  sewer  as  shown  previously  in
Figures  7,  8  and  9.  Major wastes included are those from steepwater
evaporators; starch modifying washing, and  dewatering;  syrup  refining
(cooling,  activated  carbon  treatment, and ion exchange regeneration) ;
syrup evaporation; and syrup shipping.
The condensate  from  steepwater  evaporation  constitutes  one  of  the
several major waste water sources in a corn wet mill.  Normally, triple-
effect   evaporators   are   used  with  either  surface  or  barometric
condensers.  Vapors from each of the first two  effects  passes  through
the  subseguent  effect before being discharged to the sewer.  For those
systems using surface condensers, the condensate from the  third  effect
is  sewered.   In  the  case  of barometric condensers, the third effect
condensate becomes a part of the barometric cooling water discharge  and
hence, is greatly diluted.  Limited data on characteristics of the waste
discharges  from  the  first and second effect evaporators were acquired
during the sampling program and are  presented  in  Table  6.   Selected
samples  taken  from  the  barometric  cooling  waters serving the third
effect  evaporator,  indicate  much  lower  waste   concentrations,   as
expected.   BOD5_  levels  ranged  from 10 to 75 mg/1 with typical values
reported by industry in the range of 25 mg/1.

                                Table 6
             First and Second Effect Steepwater Condensate
                      Waste Water Characteristics

                                       Range j
                                        ~
         EOD5                            723   -  93U
         COD                            1095   - 1410
         Suspended Solids                 10   -   28
         Dissolved Solids                110   -  292
         Phosphorus asP                   0.5-    0.7
         Tctal Nitrogen as N               2.U -    2.6
         pH                                3.0-3.5
Surface condensers will generate essentially the same total quan-
tity of waste constituents, but in a much smaller volume of water.
To reduce waste water flows, several plants presently recirculate
barometric cooling water and only discharge the blowdown from the
cooling tower to the sewers.  Measurements of the blcwdown from
such a system at one plant indicated a BOD5 of about 440 mg/1 and
a suspended solids content of 80 mg/1.

Data from a previous study for the Environmental Protection Agency
                                40

-------
(Table 7)  indicate that steepwater evaporation systems usinq oncf—
through cooling water generate about 4.5 to 13.4 cu m/kkq  (30 to
90 gal/SEu)  of process wastes.  Recirculating cooling water syst^mf,
on the other hand, generate about 10 percent of this flow, namely
0.6 to 0.9 cu m/kkg (4 to 6 gal/SBu) .

Additional data from the same study related waste characteristics
to raw material input and indicated a BOD5 range of 0.9 to 2.9 kg/kkq
(0.05 to 0.16 Ibs/SBu) and a COD range 1.1 to 3.2 kg/kkg  (0.06 to
0.18 Ibs/SEu) .

Modified_Starch Production-

In many, if net most, corn wet mills the waste from the production
of modified starches represents the largest single source of con-
taminants in terms of organic load.  Limited samples taken at two
mills indicated very high BOD, COD, and dissolved and suspended
solids, as indicated in Table 7.

                                Table 7
                       Finished Starch Production
                      Waste Water Characteristics

                                         Ran ge x_ rmj /1

         EOD5
         COD
         Suspended solids
         Dissolved solids
         Phosphorus as P
         Tctal nitrogen as N
         pH

These very high-strength wastes are highly variable in both composition,
flow and biodegradability.  Information  from  earlier  studies  on  the
waste  characteristics  relative  to raw material input is summarized in
Table 8.

It is important to note that the production of modified starches  varies
not  only  from  plant to plant, but from day to day and week to week in
any given plant.  Moreover, the nature of the waste water generated from
starch  modification  depends   on   the   particular   starches   being
manufactured.    For  example,  mild  oxidation  with sodium hypochlorite
generates a lower dissolved organic load  than  highly  oxidized  starch
production.    No  correlation has yet been established between the types
and amounts of starches being produced and the  waste  loads  from  this
operation.

gyrup gef inery-

In  most  mills,  waste waters are discharged from several operations in
the syrup refinery.  Most of these waste waters  are  generated  by  the
series  of  operations  generally  referred  to as syrup refining, which
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includes activated carton and ion exchange  treatment.   Typically,  ~^'"
so-called sweeteninq-off procedures require flushinq the spent carbon or
ion exchange resin with water prior to regeneration.  The first flush of
such water is usually sent to the syrup evaporator for reclamation.  Thit-
final rinse water is very dilute in syrup content and is discharged from
the  plant.   Sampling  data  indicate  that  waste  waters from the ion
exchange regeneration are high in organic content, with BOD5  levels  of
500  to  900  irg/1,  and in dissolved solids, 2100 to 9400 mg/1.  The cH
levels of the waste water were quite low, averaging about  1.8  and  the
suspended solids averaged 25 mg/1.

Other  sources  of  waste  waters  in the syrup refinery include:  syrup
(flash)   coding,  evaporation,  dextrose  production,   and   shipping.
Samples  of  wastes from the syrup cooling process at one plant gave vhe
results shown in Table 9.

                                Table 9
                           Corn Syrup Cooling
                      Waste Water Characteristics

                                            Concentration

         ECC5                                 73
         CCD~                                177
         Suspended solids                     44
         Dissolved solids                    291
         Phosphorus as P                       0.2
         Total nitrogen as N                   0.4
         pH                                    6.7


The concentration of wastes from syrup evaporation again depends on  the
type of condensers used, i.e., surface and barometric with recirculation
versus  barometric  with  once-through cooling water.  Other data on the
waste waters from  the  various  activities  in  a  syrup  refinery  are
included in Table 7.

Other_Processes-

Waste  water  streams  of  less  importance include discharges from feed
dewatering, oil extraction and  refining,  and  general  plant  cleanup.
Sampling data taken at one plant indicate that the waste waters from the
feed house contained about 140 mg/1 of COD, 40 mg/1 of suspended solids,
and  negligible amounts of phosphorus and nitrogen, and had a pH of 5.9.
Other data are also presented in Table 7.

Total_Waste_Characteristics

Most of the data accumulated from  various  sources  during  this  study
relate  to  the  total  raw  waste  characteristics from corn wet mills.
Summary data from 12 of the 17 mills are presented in Table  10.   Waste
waters   frcm   this   grain   milling   subcategory  can  generally  be
characterized as high-volume, high-strength discharges.  The BOD  varies
                                  43

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widely, from 255 to 4450 mq/1, with a corresponding range in COD.  Tho?f-
plants  with  very  low BOD5_ values typically have barometric condensing
systems using once-through cooling water.  At  the  other  extrema,  *-.h«
very  concentrated  wastes  are  from  plants using recirculated coolinq
water  (either surface or barometric condensers).

Suspended  solids  levels  in  the  total  waste  streams  show  similar
variations  ranging  from  81 to 2458 mg/1.  Once again, the plants with
low  suspended  solids  concentrations  are   those   using   barometric
condensers with once-through cooling water.

Other  waste  parameters  indicate that the pH of the total waste ranges
from about 6.0 to 8.0.  These average pH values, however,  are  somewhat
misleading  inasmuch  as wide pH fluctuations are common to many plants,
Typically,  the  waste  may  be  somewhat  deficient  in  nitrogen   for
biological  waste  treatment.   Dissolved  solids  levels  from  certain
process operations, as discussed previously, generally do not constitut"
a problem when combined in the total waste stream.  In those plants that
have minimized water use, dissolved solids  build-up  may  be  a  future
concern.

The  information  contained in the preceding table is presented in Table
11 in terms of raw material input, i.e., kg/kkg  (Ibs/MSBu) .   The  plant:
UUfflb^ES in the two tables do not correspond to one another^

EOD5_  in terms of raw material input ranges from 2.1 to 12.5 kg/kkg (119
to 699 Ibs/MSBu), and averages 7.4 kg/kkg  (415  Ibs/MSBu).   Similarly,
the  suspended  solids in the total plant waste waters range from 0.5 to
9.8 kg/kkg (29 to 548 Ibs/MSBu)  and average 3.8 kg/kkg   (211  Ibs/MSEu).
These  data  emphasize again the wide variation in waste characteristics
from the corn wet milling industry.  Possible correlations between plant
size, age, or other factors will be discussed in the next section.   The
waste  water  flows  vary frcm 3.1 to 41.7 cu m/kkg (21 to 280 gal/ SPu)
with an average of 18.3 cu m/kkg (123 gal/SBu).  Those plants with lower
waste flows per unit of production are those that  emplcy  recirculating
cooling water systems.

Factor s_AfJecting_ Wast e_Characteristj.c_s

As  noted  previously,  waste  waters  from corn wet milling plants vary
greatly in quantity and character.  This variability is  a  function  of
many  different  factors  and  attempts  have been made in this study to
correlate seme of these factors with raw waste loads,  as  discussed  in
the following paragraphs.

   _of_Plant-

In some industries, the character of waste generated is directly related
to  the age of the plants.  Such is not the case in corn wet milling, as
evidenced in Figure 10, which relates plant, age to the BODJ5 in the total
plant effluent.  The data have been gathered into three groupings with  a
dark circle representing the mean, and the boundaries of the  rectangles
representing  the  range  of  average values in each grouping.  Clearly,
                               45

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there is no discernible relationship between the total  waste  load  and
the  age  of  the  plants.   In  fact,  at  least  one of the new plants
generates more wastes per unit of raw material input than several of the
older plants.  It should be noted that the age of plant in this industry
does not accurately reflect the degree  of  modernization  in  terms  of
types  of  equipment.   Because  of competition and market demands, most
corn wet mills are reasonably modern and very similar in  basic  produc-
tion techniques.

Size_of_Plant-

Several  comparisons  were  made between the size of plant, expressed in
normal grind of raw material, and total plant waste loads  as  shown  in
Figures 11, 12 and 13.  The total daily volume of waste water discharged
was found to show a general relationship with the plant capacity, Figure
11,  as  might  be  expected.  At the same time, the data reflect a wide
range in waste water discharges as a result of vastly different  process
and cooling water use practices.

The information on BOD^ and suspended solids has been grouped into three
plant  size  ranges, which might be termed small, medium, and large.  As
shown in Figures 12 and 13, no discernible  relationship  can  be  found
between plant capacity and either of these two pollutant parameters.

Water_Use_and_Waste_Water_Discharge-

It  has  been  speculated that there might be a relationship between the
total waste load and the volume of water used or discharged.

Figures 14 and 15 were developed to evaluate this hypothesis and clearly
indicate that no such correlation exists.  Once  again,  the  data  have
been grouped in a convenient manner for presentation.

PgQ<3uct_Mix-

Because  certain  products,  namely  modified starches, result in higher
waste loadings than other products, there was reason to believe  that  a
relationship might be apparent between product mix and total waste load.
For example, it might fce reasoned that a plant producing only corn syrup
would  have  a  lower raw waste load per unit of raw material input than
one producing a product mix with a high percentage of modified starches.
The available data from 12 plants regarding both  product  mix  and  raw
waste characteristics showed absolutely no correlation between these two
variables.   It  is  known  that changes in product mix at a given plant
will alter the total plant raw waste load, but the data refute any claim
that product mix is a direct measure  of  the  relative  waste  load  of
different plants.

The product mix at the reporting mills varied from 100 percent starch to
100  percent  syrup  and  sugar.  At most of the plants, the product mix
varied between about 30 and  70  percent  starch.   Even  near  the  two
extremes,  i.e.,  zero  and 100 percent starch, there was no discernible
relationship between product split and waste  loads.   Furthermore,  the
                                48

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more limited information on the quantities of modified starches produced
indicated nc correlation with waste loads at different plants.

Pl<*nt_QEerating_Procedures-

There  appears  to  be  a  definite  relationship  between general plant
operating procedures and the amounts of wastes discharged.  Those plants
known to have good housekeeping operations and close operational control
do tend to have lower waste loads, although this is not universally  the
case.   Clearly,  careful  monitoring  and control of process operations
will reduce spills and, hence, the total amounts  of  waste  discharged.
The effect of good housekeeping and operational controls is difficult to
quantify,  although some industry sources indicate that waste reductions
of 20 to 30 percent, or more, can be achieved through these measures.

Summary.-

In summary, nc quantitative relationships could be  established  between
the  total  plant  raw  waste loads and such factors as plant size, age,
product mix, water use, and operational procedures.  At the  same  time,
it  is  important  to  recognize that many of these considerations will,
indeed, influence the character of the total waste discharges.


CORN DRY MILLING

Water_Use

Water use in corn dry milling is  generally  limited  to  corn  washing,
tempering,  and  cooling, as shown on the product flow diagram presented
earlier, Figure 2.  Not all mills use water to clean the corn,  probably
because  the  resultant waste waters constitute a pollution problem.  It
is believed that most of the larger mills, however,  do  wash  the  corn
although  data  on  the  number  of such installations is not available.
Water use for this purpose ranges from about 0.45 to 1.2 cu m/kkg  (3  to
8 gal/SBu).

After  washing, water is added to the corn to raise the moisture content
to about 21 to 25  percent  in  order  to  make  it  more  suitable  for
subsequent  milling.   Only  enough  water is added in this operation to
reach the desired moisture content and no waste water is generated.

Waste^Water^Characteristies

Other than infrequent car washing, the only process waste water in  corn
dry  milling  is that originating from the washing of corn.  Data on raw
waste characteristics from three plants are presented in Table  12.   In
one instance, the plant also processes soybeans and the waste waters are
combined.   This same mill generates some waste water from air pollution
control  equipment   (wet  scrubbers)  on  corn  and  soybean  processing
systems.   These  wastes are excluded from the data in Table  12 inasmuch
as they originate from secondary processing of milled corn  rather  than
the basic milling sequence covered in this document.
                                  54

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Average  waste  water  discharges  from the three mills range from about
0.48 to 0.9 cu m/kkg (3200 to 6000  gal/MSBu).   The  waste  waters  are
characterized by high BOD5 and suspended solids concentrations.   The raw
waste  water  BOD5  values  average  1.14  kg/kkg (64 Ibs/MSBu), and the
suspended solids average 1.62 kg/kkg (91 Ibs/MSBu).

Factors_Affeeting_Waste_Water_Characteristics

Insufficient data were available to establish any relationships  between
waste  water  characteristics  and  such factors as plant age, size, and
operating procedures.  Clearly the  size  of  plant  and  the  type  and
cleanliness  of  the  corn  will  influence  both  the  flow  and  waste
characteristics, but in ways that cannot be defined at this time.


WHEAT MILLING

The normal trilling of wheat into flour uses water only in tempering  and
cooling  and no process waste waters are discharged.  A few normal flour
mills do wash  the  wheat,  but  the  vast  majority  use  dry  cleaning
techniques.    Accordingly,   the  remainder  of  this  discussion  will
concentrate on bulgur production.

Vjater_Use

As indicated in the product flow diagram, Figure 4, water  is  added  to
the  wheat  in the soaking operation.  Depending on the specific process
employed, water  may  te  added  at  as  many  as  four  locations,  all
essentially  relating  to  the  same soaking operation.  Water usage for
typical bulgur plants ranges from about 115 to 245 cu m/day   (30,000  to
65,000  gpd),   Most of this water is used to raise the moisture content
of the wheat from 12 percent, as received, to about 42 percent.

W§§te_Water_Characteristics

The only source of process waste water, in the production of bulgur,  is
from steaming and cooking.  As the grain is transferred from bin to bin,
water  is  added  on  the  conveyors and waste water is discharged.  The
total quantities of waste water from a  given  bulgur  plant  are  quite
small,  ranging  from  38  to  115 cu m/day (10,000 to 30,000 gpd).  Raw
waste data from two plants are presented in Table 13.  The  BOD5  values
cited  in  the accompanying table correspond to an average of about 0.11
kg/kkg (5.9 Ibs/MSBu) of  BOD5  and  0.10  kg/kkg   (5.5  Ibs/  MSBu)  of
suspended solids.

                                Table 13
                      Waste Water Characteristics
                           Bulgur Production

                                            Concentration mg/1

        BOD5                                 238 - 521
        COD                                  800
                                 56

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Suspended solids
Phosphorus as P
Tctal nigrogen as N
pH
                                              294 -  414
                                                5.6
                                                3.6
                                                5.8
?^£t2E§_Mj:e_cting_Waste_Water_Char act eristics

Factors  influencing waste water characteristics undoubtedly  include  the
particular production methods  used,  type  of  wheat,   and   operational
procedures.   Unfortunately, insufficient data are  available  to  evaluate-
quantitatively the influence of these factors.
PICE MILLING

The ordinary milling of rice to  produce  either  brown   or   whit^   ricc-
utilizes nc process waters and, hence, generates no waste waters.   Viator
is  used  in  the production of parboiled rice and the remainder  of this
discussion will focus on this production method.

Vjater_0se

In the parboiled rice process, water  is added in thc  steeping or  cookina
operation, as shown in the product flow diagram. Figure  6.   Water use  ir:
the industry varies from about 1.4 to 2.1 cu m/kkg  (17 to 25  gal/cw1-) .
Additional  water  is  ue^ed  in  boilers  for  steam  production  for -t-h^-
parboiling process.  At least one plant  uses  wet  scrubbers  for   dus*-
control thereby generating an additional source of waste  water.

Paw_Vaste_Water_Characteri. sties

Limited  data are available on raw wast<= water characteristics from ric-
parboil inq.  The information that is  available is  summarized  in   Tafcl'
14.  Th- raw waste loads presented in the table correspond to 1.8 kg/kk<,
(0.18  Ibs/cwt)   of  EOD^  and  0.07  kg/kkg  (0.007 Ibs/cwt)  of su
solids.  In general, the waste may be characterized   as   having   a
soluble BODj) content and a low suspended solids level.
                                Table 14
                      Waste Water Characteristics
                         Parboiled Rice Milling
                                            Concentration  mg/1
BOD5
COD
Suspended solids
Dissolved solids
Phosphorus as P
Total nitrogen as N
                                     1280 -
                                     2810 -
                                      33 •*
                                     1687
                                      98
                                       7.0
                                                     1305
                                                     3271
                                                      77
                                  57

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Factors Affecting Waste Water Characteristics

Based  on the very limited amount of data available, it appears that the
waste characteristics from parboiled  rice  plants  are  quite  similar.
While  there are some differences in flow volumes, the total waste loads
per unit cf production are similar.
                                 58

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                               SECTION VI

                   SELECTION OF POLLUTANT PARAMETERS


The waste water parameters which  can  be  used  in  characterizing  the
process  waste  waters  from  the grain milling industry are as follows:
EOD5 (5-day), suspended solids, pH,  COD,  dissolved  solids,  nitrogen,
phosphorous, and temperature.  These parameters are common to the entire
industry  but  are  not always of equal importance.  As described b°low,
the selection of the waste water control parameters  was  determined  by
the  significance  of  the  parameters  and  the  availability  of  data
throughout each industry subcategory.


MAJOR CONTROL PARAMETERS

The following selected parameters are the most important characteristics
in grain irilling wastes.  Data collected during the preparation of  this
document  was  limited in most cases to these parameters.  Nevertheless,
the use  of  these  parameters  adequately  describes  the  waste  water
characteristics  from  virtually  all  plants in the industry.  POD5 (5-
day) , suspended solids, and pH are, therefore, the  parameters  selected
for effluent limitations guidelines and standards of performance for new
sources.

                          (.BOD_5]_
BOD5_ is an important and widely accepted measure of the biodegradability
of  organic  matter in waste waters.  Most plants routinely measure EOD5_
in their waste waters.  Typical BOD5_ levels in all of the  subcategories
are  quite  high, ranging frcm several hundred to several thousand mg/1.
Discharge of  such  wastes  to  surface  waters  can  result  in  oxygen
depletion and damage to aquatic life.
The suspended solids levels of the raw waste waters, in most segments of
this  industry,  are  quite  high,  ranging from about 500 to 3500 mg/1.
Parboiled rice mills and specific plants  in  other  subcategories,  may
have  substantially  lower  suspended  solids  levels.   The  very  high
suspended solids level common to the industry, however, may constitute a
serious pollution problem if discharged to  surface  waters.   Moreover,
the  solids are generally finely divided grain particles and represent a
sizable fraction of the organic load in the wastewater.

EH

The pH levels in the wastes from the various  subcategories  covered  in
this  document vary appreciably.  Generally, the waste waters tend to be
neutral or slightly acidic.  Under certain conditions, in some wet  corn
irills,  the  combined waste stream may be very acid or quite alkaline at
                                  59

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different times.   pH is an essential control parameter for treatment  of
the waste and regulation of the discharges.


ADDITIONAL PARAMETERS

Chemical. _Oxygen_Demand	(COD)_

COD  is  a  chemical  measure  of the organic content and, hence, oxygen
demand, of the waste water constituents.  As with most food wastes,  the
COD  is  considerably higher than the BOD, usually by a factor of 1.5 to
2.0  Several companies in the grain milling industry rely on  COD  as  a
much more rapid measure of the organic content than BOD, and use it as a
rapid  monitoring technique for the waste.  In most instances, the ratio
of COD to EOD5 in the raw waste can be established fcr a given plant and
COD can serve as  an excellent control parameter.  However, the COD  data
collected  during  the  preparation  of  this  report  was  sparse.   No
definitive relationship between COD and BODjS (5-day)  can be  established
at  the present time.  The fact that the chemical nature of the organics
may differ from plant to plant may preclude the use  of  a  uniform  COD
standard  for  each  subcategory.   Therefore,  it  was  concluded  tha4-
effluent limitations guidelines and standards of performance  could  not
be determined for COD.

Inorganic_Dissolved Solids

There  are  a  number  of  sources  of inorganic dissolved solids in the
various subcategories of the  grain  milling  industry.   These  include
wastes   from   water   treatment,  cooling  water  blowdown,  deionizer
regeneration and various  processes  in  the  plant.   The  increase  of
dissolved solids in the waste waters were not found to large.  Moreover,
the  sources  of  inorganics mentioned above are in many cases common to
other  industries.   Since  these  problems  are  difficult  to   handle
practically  and economically, EPA will consider effluent guidelines for
these sources at a later data,  and  they  are  not  discussed  in  this
report.
Many  operations in grain milling inherently elevate the temperatures of
the resultant process waste streams.   This  is  especially  true  where
steeping,  soaking,  or  cooking processes are used, such as in wet corn
milling, bulgur production,  and  parboiled  rice  manufacture.   Direct
contact barometric cooling water is a major source of heated waste water
in some ccrn wet mills.  Temperatures from selected waste streams and in
some  instances  from combined total plant wastes, sometimes approach 38
degrees C  (100 degrees  F).   Elimination  of  once  through  barometric
condenser  water  by the use of cooling towers will significantly reduce
this problem.  The blowdown from the cooling tower will be discharged to
the treatment plant where it will either be cooled prior to treatment or
in the  treatment  process  itself.   Non-contact  cooling  water  is  a
separate   industrial  category  for  which  EPA  will  address and issue
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guidelines at a later date.  Therefore, temperature was not selected  as
a control parameter for the purposes of this report.
Phosphorus  levels  in corn wet milling waste waters generally appear ro
be quite lew.   The data on other subcategories indicate that  levels  of
some significance may be present in the wastes.  In particular, corn dry
milling   and   parboiled   rice  production  appear  to  generate  high
conceritraticns of phosphorus ranging from about 30  to  65  mg/1.   This
information is based on limited data, and is not sufficient to determine
effluent limitations.

Nitrogen

Nitrogen levels of the wastes have been measured throughout the industry
and  generally  tend  to be below 20 mg/1, usually below 10 mg/1.  These
levels may te necessary to achieve good biological treatment.   However,
no  information  is  available  to  determine  this  requirement, nor to
determine effluent limitations.
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                              SECTION VII

                    CONTROL AND TREATMENT TECHNOLOGY


INTRODUCTION

Except in the corn wet  milling  industry,  little  attention  has  been
focused  on  either  in-plant  control  or treatment of the wastewaters.
Many of the mills discharge to municipal systems while the waste  waters
from  other  plants flow into large rivers where the impact has not been
of  great  concern  until  recently.   Only  in  corn  wet  milling  has
considerable attention been focused on both in-plant control and end-ot->-
process  treatment.  The emphasis on waste water control in tnis segment
of the industry is, of course, a reflection of the large  quantities  of
waste  waters  discharged  in  contrast  to  the  much  smaller  amounts
generated by ether types of  grain  milling.   In  many  instances,  the
treatment technologies developed for corn wet milling can be transferred
to the ether industry subcategories.


COFN WET MILLING

Wagte_Wat€r_Charact.erist ics

As  developed  in  detail  in  section V, the waste waters from corn wet
mills contain large amounts of BOD^ and suspended solids.  Depending  on
the  type  of cooling water system employed, the concentrations of these
constituents range from moderate to high.   Most  plants  have  isolated
their  major  waste  streams  into  a concentrated stream for treatment.
Once-through cooling water systems are being replaced with recirculating
systems, in several instances.

In concentrating the waste streams, the mills have reduced the volume of
water to be  treated  and,  hence,  the  cost  of  treatment,  but  have
increased   the   operational   difficulty  of  achieving  low  effluent
concentrations.  In essence, it is much more difficult to reduce  a  raw
waste  BOD5 of 1,000 mg/1 to an effluent of 30 mg/1 than it is to reduce
an influent BOC5 of 250 mg/1 to the same 30 mg/1.

In evaluating waste water control in the corn wet milling  industry,  it
is  essential  to  evaluate  both in-plant control measures and effluent
treatment systems.  Good in-plant controls can greatly reduce the  total
raw waste load and improve treatment plant efficiency.

In-Plant_ Centrcl_Measures

All  corn wet mills presently incorporate many water recycling and reuse
techniques.  In the early days of corn wet mills, little  if  any  water
conservation  or  by-product  recovery was practiced.  Through research,
new markets were found for materials that  were  once  wasted,  such  as
steepwater.   Efforts  to improve product recovery and simultaneously to
reduce waste discharges, have led to innovative process operations which

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utilize recycled water wherever possible and generally  incorporate  up-
to-date process technology.

The  degree  of  in-plant control practiced by individual mills reflects
many factors, not the least  of which are the physical constraints of the
existing facility.  The  physical  space  available  in  the  plant  may
prevent  the installation of certain types of in-plant controls, such as
holding  tanks  for  overflows.   While  physical  constraints  are  not
necessarily  a  reflection of plant age, many process controls difficult
to implement in older  plants  have  been  incorporated  into  the  con-
struction  of  new  mills.  In the following paragraphs, a number of in-
plant modifications involving water conservation and/or waste  reduction
are  suggested.   Many  of  these  have been incorporated in one or more
plants in the industry, but  the ability to implement any of them rrust be
evaluated fcr each individual plant.

Cooling_Sy,stenis-

The cooling systems used in  this industry can be characterized  as  non-
contact  cooling  surface  condensers  and  contact  cooling  (barometric
condensers).  They can  be  further  subdivided  into  once-through  and
recirculating  systems.   Since  non-contact  cooling  water,  both once
through and recirculated are common to many other industries,  EPA  will
issue  guidelines on the non-contact cooling water area at a later date.
This report concerns itself  with organic contamination of  both  contact
cooling  water (barometric condenser)  water and condensates frotr, surface
condensers.

One of the major waste loads from any corn mill is the  condensate  from
steepwater   and   syrup  evaporators.   Where  surface  condensers  are
employed, the condensate is  discharged as a concentrated  waste  stream,
suitable  for  treatment.   Many plants use barometric condensers on the
evaporators and the resultant condensate is ccmingled with  the  cooling
waters,  resulting  in  large  volumes  of dilute waste.  Because of the
large voluire and low concentration, the removal of  entrained  BOD5  and
suspended solids is both expensive and difficult if once-through cooling
waters are used.

There  are  two  possible  remedies  to  this problem and both are being
implemented by various companies in the industry.  One  approach  is  to
convert  all  barometric  condensers  to  surface  condensers,  but this
solution is not always practical.  Physical restraints  in  some  plants
prevent  the  installation  of large surface condensers.  Moreover, such
condensers are expensive and generally  require  more  maintenance  than
barometric  condensers.   In spite of these difficulties, several plants
have converted many of their barometric condensers to surface units.

An alternate approach, also being employed by several companies,  is  to
recirculate  the  barometric cooling water over cooling towers.  In this
manner, the waste volume is reduced to the  blowdown  from  the  cooling
system  and  is  much more concentrated than in the once-through system.
Moreover, physical and biological processes active in the cooling  tcwer
effect some reduction in the total BOD5 load from the evaporators.
                                64

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Cger at i.onal_Contr ol_o^_ Evaporator s-

The   control  exercised  in  the  operation  of  steepwater  a no  syrup
evaporators can have a significant effect on the total organic carryover
in the condensate.  From a waste reduction standpoint, two problems  are
prevalent  in  evaporator  operation.   The  emphasis in operation is on
obtaining maximum steepwater cr syrup throughput in the evaporators  and
not  on  minimizing organic carry-over.  Accordingly, a number of plants
operated their evaporators at very heavy loading rates, rates which  are
not  commensurate  with  good waste control.  Lack of careful control by
the  operators  is  a  second  evaporator  operational  problem.    Poth
situations lead to the frequent boiling over of the ligucr and resultant
heavy  waste  discharges.   Improved  operator control and expanded eva-
porator capacity can greatly reduce these problems.
Ihe arrount cf organic carry-over from evaporators can also be reduced by
installing modern entrainment separators  or  demisting  devices.   Many-
plants  have  already  incorporated  better  entrainment  separators and
research continues on ways to reduce organic  carry-over  even  further.
It is also important that this type of equipment be well maintained.

Reuse_of_Process_Waste_Waters-

Although  major recycling and reuse of process waste waters is practiced
at all corn wet mills, additional recycling is possible at  most  plants
and will have a significant effect on total waste effluent.  At the same
time  it  must  be  recognized  that  the  extent of reuse is subject to
restraints imposed by the Food and Drug  Administration  regarding  good
manufacturing  practices  for  food  processing.  Typically, fresh water
enters the irilling operation in the starch  washing,  and  waste  waters
from  ordinary  and  lightly  modified  starches  is  reused in numerous
processes in the starch, feed, and mill houses.  In these three areas of
the plant, waste waters are primarily generated only from the washing of
modified starches and from steepwater evaporation.

Water reuse practices in the refinery area vary considerably  from  mill
to  mill.   In many plants, waste waters are sewered from syrup cooling,
enzyme production, carbon treatment, ion  exchange  regeneration,  syrup
evaporation,  dextrose production, and syrup shipping.  At least some of
these wastes are lightly  contaminated  and  suitable  for  reuse.   For
example, at seme mills condensate and syrup evaporation is used as input
water  for  activated  carbon and ion exchange washing and regeneration.
Such practice not only greatly reduces total water use in the  refinery,
but  also  decreases  the  total  waste  load from these operations.  In
essence, product recovery is increased by this type of water reuse.

Improved Solids _gecpyery-

Screens, filters, and centrifugal separating equipment can  be  used  to
recover  sclids  from  waste  streams  directly  at  their  source.  For
example, centrifugal devices can be used on starch filtrate  streams  to
                                65

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recover  sclids  passing through holes that develop in the filter media.
Such solids can then be returned directly as product.   In  some  mills,
filters  or  screens  are  used in the gluten processing area to recover
solids during start-up and shut-down activities and return these  sclids
to by-product recovery.

Waste  waters  from  the finished starch department, exclusive of highly
modified starch wastes, can be directed to a clarifier or  thickener  to
accomplish additional solids recovery.  Rather substanital quantities of
solids can be recovered by this method and returned either to process or
sold  directly  as  mill starch.  Several mills have used settling tanks
for this purpose for many years.

Containment of Qerf lows
In a typical corn wet mill, overflows and spills from various pieces  of
equipment  cccur  quite frequently.  When sewered directly, these spills
constitute a large waste source.   Although good operation  can  minimize
the  frequency  and  amount  of  such  process  upsets,  they  cannc> be
eliminated and in-plant provisions should be made to contain these waste
water.

Specifically, those areas prone to upsets should be diked and  sumps  or
monitoring  tanks  installed  in  the area to retain the overflows.  The
floor spillage can then be discharged gradually  to  these  sewer,  thus
reducing shock loads on the waste treatment system.

In new plants, the specific equipment overflows can be piped directly to
monitoring  tanks  and  floor  spillage  largely  eliminated.  This same
practice can be instituted in existing plants, but  to  a  more  limited
degree.   Once  the overflows have been contained, their contents can be
analyzed and decisions made as to whether the material can  be  recycled
back  into  the  process,  discharged  to  by-product  recovery,  or  if
absolutely necessary, discharged to the sewer.  Such monitoring controls
are used by a few plants in the industry and have proved very  effective
in reducing total plant waste discharges.  Simultaneously, they have the
added benefit of improving general plant housekeeping.

                      Wa s te s -
Perhaps  the  most effective means of reducing overall plant waste loads
is to institute a careful monitoring program of all major process  waste
streams.  Such a program involves frequent sampling of the waste streams
and  analysis  for  both  product losses and waste load.  Initially, the
program will identify the major sources of wastes and permit  production
personnel  to  correct  any  process  deficiencies thereby reducing, and
perhaps eliminating, many waste sources.

The effectiveness of  such  a  monitoring  program  is  limited  by  the
importance  attached  to it by company management.  Where management has
recognized the need for reducing waste discharges and has supported  the
monitoring  effort,  very  substantial  reductions  in the quantities of
pollutants discharged have been realized.  commensurate with this  waste
                                 66

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reduction  has been increased product recovery, which a+ least partially
offsets the ccst of the monitoring.

General_Pl.ant_Orjeratj.on_and_]lous_ekeejDing-

As in many industries, general operational and  housekeeping  procedures
have  a  marked effect on the amount of wastes discharged.  Those planrs
practicing clcse operational  control  and  good  housekeeping  tend  to
generate  far  less  wastes  than  plants at the opposite extreme.  Cnce
again, the impetus for improving operational and housekeeping procedures
must come from top management if it is to be effective.
Eecause of the unique nature of each plant in this  subcategory,  it  is
impossible  to  estimate  the  overall  effect  on total waste discharge
achieved by instituting the above in-plant  modifications.   In  general
terms,  it is likely that total waste loads can be reduced by 25 percent
or more by these activities in plants where they are  not  practiced  at
this time.

It  is equally difficult to quantify the costs associated with effecting
these in-plant controls, inasmuch as the needs and the  equipment  costs
will  vary  for each plant.  These costs will have to be evaluated on an
individual plant basis, taking into account various alternatives,  plant
layout, physical restraints, and other factors.

Treatment Processes

Of  the  seventeen  plants  in the industry, at least seven provide some
type of treatment or pretreatment of  the  plant  effluent.   There  are
three  activated  sludge systems in operation that discharge directly to
surface waters and one additional system  that  is  under  construction.
Three  activated  sludge  pretreatment  plants  discharge  to  municipal
systems and a  unique  fungal  digestion  pretreatment  plant  is  under
construction  at  a fourth plant.  More limited pretreatment, consisting
of settling and some aeration, is  provided  at  another  plant.   Pilot
plant  studies  were  conducted  on the joint treatment of municipal and
corn wet milling wastes using the pure oxygen system  and  a  full-scale
treatment  facility  plant  is  now  under  construction.   The  various
treatment systems that are in use and the results  of  two  pilot  plant
studies are described below.

Ccm£l.ete_Treatment-

Three corn milling plants have waste treatment facilities that discharge
treated effluent directly to the receiving waters.  Each of these plants
is  of  the  activated sludge type, although they vary somewhat in their
detailed process operations.

Plant A — Vvaste treatment Plant A handles about 2,460 cu  m/day   (650,000
gpd)   of  concentrated  wastes  from  a medium-sized corn wet mill.  The
treatment plant does not receive the large  quantities  of  once-through
                                 67

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cooling  water  used  at  the  plant,   and  which contain relatively low
concentrations of BODjjj and suspended solids.  The waste  water  influent
to  the  treatment plant contains over 3,000 mg/1 of COD and 700 mg/1 ot
suspended solids.

The treatment sequence itself consists of complete-rrdx activated sludae,
secondary clarification, aeration in two lagoons operated in series, and
clorination.  No primary clarification is provided in this system.   The
activated  sludge  basin  provides up to 48 hours detention, and the -trwo
lagoons  following  the  secondary  clarifier  provide  up  to  16  days
additional  retention.  The first of the lagoons is fully aerated, while
the last portion of the second basin is quiescent to provide  additional
settling.

Effluent characteristics from this treatment facility are as follows:

                                  Average   Range
    BOD5                           35         6-95
    COD                           266       102-525
    Suspended Solids              169         8-372

The  relatively  high suspended solids content in the effluent, prohably
reflects some algae growth in the lagoons.  The nature of  corn  milling
wastes, however, tends to generate solids handling problems in treatment
systems.   At the time of the sampling program at Plant A, the treatment
facility was in an upset  condition  as  evidenced  by  heavily  bulking
sludge in the secondary clarifier.  During this period of time, effluent
BOD5  from the treatment plant averaged 444 mg/1 with a suspended solids
content of 213 mg/1.  Such upsets are common to all treatment plants  in
the  corn  wet  milling industry, and various reasons for them have been
hypothesized including shock loads of sugars,  specialty  starches,  and
acids or alkalis.

In  terms  cf BOD5_ removal, Plant A represents the best treatment in the
industry.  Suspended solids removal, however, is below expectations.

Plant B — The second plant to be discussed handles the waste from ancther
medium-sized corn  wet  mill.   The  facility  consists  of  an  aerated
equalization  basin,  two parallel complete-mix activated sludge basins,
secondary clarification, and dissolved air flotation.   This  plant  has
been  the  recipient of an Environmental Protection Agency demonstration
grant and has been in operation for about two years.

The plant receives a concentrated waste stream of about 3,030  to   3,785
cu  m/day   (0.8  to 1.0 mgd) containing 1,400 mg/1 of BOD, 2,100 mg/1 of
COD, and 350 mg/1  of  suspended  solids.   Once-through  cooling   water
containing  seme  barometric  condensate  is discharged to the receiving
water without treatment.

The aerated equalization basin provides 24-hour  retention  to  equalize
waste  load  and  pH  fluctuations.  In the summer, the discharge in the
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equalization basin may be passed over a cooling tower in order to reduc«
the temperature prior to the activated  sludge  process.   Plant  R  was
designed en the basis of a food-to-microorganism ratio of 1.1 to 1.7r in
terms  of  COD:MLSS  (mixed liquor suspended solids) , and provides about
16-hour detention.  The  dissolved  air  flotation  following  secondary
clarification  was intended to polish the final effluent by removing any
floating fciclcgical sclid.

The design effluent from the plant is a BOD5 of less than 40 mg/1 and  a
suspended  solids content of less than 45 mg/1.  Performance to date has
been well above these effluent levels, in spite of many modifications to
operating procedures.  Evaluations by  Environmental  Protection  Aacncy
personnel  indicate that the plant was overloaded initially with a food-
to-microorganism ratio of 0.8 in terms of BOD:MLSS.  Effluent  POD5  and
suspended  solids  were  usually  several  hundred mo/1 during the early
periods of operation.  Efforts by plant personnel have reduced  the  raw
waste   loading   to  the  plant  and  the  food-to-microorganism  ratio
(BOD:MLSS) has now dropped to about O.U.  Effluent  characteristics  for
the last six months of 1972 were as follows:


                                  Average   Range
                                  _ rncj/l_
    BOD5                           79       5-994
    Suspended Solids              142       4-1260

Sampling  data  taken during this study over a four-day period indicated
an effluent BOD5 of 10 mg/1 or less and a suspended  solids  content  of
about  50  mg/1.   The  performance  of Plant B, particularly during the
first three days of the sampling, was exceptionally good and believed to
be the best operation yet achieved by this facility.  Towards the end of
the sample period,  however, sludge bulking occurred and the final  day's
suspended  solids  analysis  was  just over 100 mg/1.  Plant performance
during the week of  the sampling program was a  graphic  illustration  of
the   effect  that   upsets  in  this  industry  can  have  on  treatment
efficiency.  The equalization basin  certainly  dampens  the  effect  of
shock loads, but upsets still occur frequently.

The  performance  of Plant B in recent months is a vast improvement ever
early operations.  As the waste load to the plant has  been  reduced  by
in-plant  modifications,   the  average  effluent  quality  has improved.
Based on the information  available about this  plant,  it  appears  that
future  activated  sludge  systems  should  be  designed  with a maximum
BOD:MLSS ratio of 0 . 4 and possibly lower.

Plant c-~ the third treatment facility, Plant C, is a new, complete  mix
activated  sludge plant handling about 760 to 1,600 cu m/day (200,000 to
425,000 gpd) of concentrated wet milling wastes from a small mill.   The
system consists of  primary sedimentation, complete-mix activated sludge,
and   clarification.    A  cooling  tower  is  provided  to  reduce  the
temperature  of  the  wastes  during  summer  months.   Influent   waste
concentrations  are  about  1,600  mg/1 of BOD and 600 mg/1 of suspended
                                 69

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solids.  Because of its newness, only  limited  data  are  available  on
effluent  characteristics.   Effluent BOD5 levels of 200 to 400 mg/1 and
suspended solids of 150 to 300 mg/1  have  been  reported.   The  common
problem  of  solids separation has already appeared at this facility and
efforts are apparently underway tc control sludge bulking.

I! £§ t £§ a £m e D t _ P la n t s_ -

Of the four kncwn pretreatment plants in  the  industry,  three  provide
some  form  of  activated  sludge  treatment  prior  to  discharge  to a
municipal system.  The fourth plant, which  will  not  be  discussed  in
detail, provides some settling and limited aeration.

Plant  D--Pretreatment  Plant  D serves a small mill and consists of two
large aerated lagoons that can be operated  either  in  parallel  or  in
series.  They provide about 5 days detention for the influent flow which
averages about 3,785 cu m/day (1.0 mgd) .  About seven months of sampling
of  treatment plant characteristics indicated the following influent and
effluent results:


                                  Average   Average
                                  Influent  Effluent
    BOD5                          2,330     1,080
    COD                           4,560     2,870
    Suspended Solids                895     2,215

Data taken during the sampling program for this study indicated somewhat
lower results en both  influent  and  effluent.   These  lower  effluent
values were possibly the result of the recent reactivation of one of the
lagoons  which  had  been  drained  for  repairs.   In  any  event,  the
pretreatment plant provides adequate  treatment  under  the  contractual
terms  with  the  local  municipality.  It should be noted that effluent
solids from the treatment plant exceed the  influent  values  reflecting
the production of biological solids in the system.

Plant  E — The  second pretreatment plant provides complete-mix activated
sludge treatment for a design flow of below 3,785  cu  m/day   (1.0  mgd)
from  a  small  mill.   The  system consists of two aerated equalization
basins with nutrient addition and pH control, followed by a complete-mix
activated sludge process, and secondary clarification.   This  plant  is
relatively  new  and  has been subject to frequent upsets.  Effluent COD
and suspended solids are reported to be about 1,000 mg/1  and  260  mg/1
respectively.   In  general,  the effluent levels are sufficient to meet
the  pretreatment  limitations  proposed  by  the  local   municipality.
Treatment  plant  efficiency  is  expected  to  improve  markedly as the
production  plant  operations  and,  hence,  raw  waste  characteristics
stabilize.

Plant  F--This  pretreatment  plant receives the concentrated waste flow
from a large corn wet mill.  The influent waste flow is about  3,210  cu
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m/day  (0.85  mgd)   with a BOD5 level of about 2,600 mg/1.  The facility
consists of four aeration basins and secondary  clarification  prior  to
discharge  to  the  local  municipal  system.  Certain cooling water and
other wastes from the mill do  not  go  through  this  treatment  plant,
Effluent levels are reported to be generally in the range of 500 mg/1 of
BOD.   Results  of  the  sampling  program were somewhat lower, as given
below:


                                  Average   Pange
    BOD5                           280       68-415
    COD                           1317      488-2206
    Suspended Solids               889      288-1395


Sludge bulking has been a frequent problem at this plant over the  years
that  it has been in operation.  The facility itself consists of various
aeration basins, some operated in series and others in  parallel.   Many
of  the  basins  have  been  converted  from  other prior uses and it is
difficult, if not impossible, to extrapolate treatment practices at this
plant to the design of new facilities.

Pilot Plant Studies-

At least three new treatment or pretreatment plants are presently  under
construction.   Data  on  pilct  plant  studies  for  two  of  these are
available and discussed below, together with the design  parameters  for
the third plant,

Plant  G--Pather  extensive pilot plant studies were run, using one- and
three-stage pure oxygen and air activated sludge  systems,  on  combined
wastes  from  a  mediuir  sized  corn  wet  milling  plant  and the local
municipality.  The  reported  pilot  plant  data  on  both  plants  were
somewhat  sporadic,  particularly  in terms of suspended solids removal.
Generally, the data demonstrated the applicability of both  pure  oxygen
and  air  activated  sludge  systems  for  the treatment of the combined
wastes.  The process design consultants have  concluded  that  the  pure
oxygen  system  offered  certain  advantages,  particularly  in terms of
solids handling.  Effluent BOD5> values for the first three months of the
oxygen pilct plant usually ranged from 200 to 400 mg/1, but dropped well
below 100 mg/1 for the last two months of operation.  Results  with  the
air  system  appear  to  be  roughly  comparable  to those achieved with
oxygen.

A full-scale pure oxygen system has  been  designed  and  is  now  under
construction  to  handle  the  combined municipal and industrial wastes.
Design criteria for the plant are for a BOD:MLSS ratio  of  0.5  to  0.7
with a MLSS concentration of 3,000 to 4,000 mg/1.  There are indications
that  pure  oxygen may offer some advantages in reducing sludge bulking,
but  the  available  information  throughout  the  country  in   related
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industries does not yet substantiate this hypothesis.  Treatment Plant G
will certainly provide an adequate test for this theory.

Plant H--This pretreatment plant will receive wastes from a medium sized
corn  mill.   The  system  is  quite unique in that it depends on fungal
disgestion as opposed to more conventional biological treatment methods.
Pilot plant studies were conducted in a 50,000 gal aerated tank  with  a
detention  time  of  16  to  24  hours.   In order to promote the fungal
growth, the system was operated at a pH of 3.5 to  6.0.   Influent  EOD5
concentrations  ranged  from  700  to  4,800  mg/1, with effluent values
normally ranging between 100 to 500 mg/1.  The  mixed  liquor  suspended
solids, in this case the fungal mass, ranged from 500 to 1,800 mg/1.

The  results  of  the  pilot  plant studies have prompted the company to
construct a 3.0 mgd pretreatment plant, based on fungal digestion.   Th^
system  will  consist  of  24-hr  equalization,  pH  adjustment,  funqal
digestion, and final clarification using settling and filtration.

The pilot plant results, while  quite  interesting,  do.  not  appear  to
indicate  any  substantial  improvement  in  effluent  quality over mor°
conventional biological treatment systems.  There may be some  advantage
in  terms of solids handling, inasmuch as the fungal mass apparently can
be removed more readily from the  final  effluent.   Plant  l--Pres<" nt ly
under  construction,  this  treatment  plant is designed to handle about
11,355 cu m/day  (3.0 mgd)  of wastes from a large  corn  mill.   In-plant
control measures are being taken to isolate the major waste sources into
a concentrated waste stream, which is expected to have a BOD5 content of
1,600 mg/1.

The  treatment  system  will  consist  of grit and oil removal, nutrient
addition and pH control, equalization, cooling over a cooling tower when
necessary, a roughing plastic-media trickling filter, activated  sludge,
secondary  clarification,  chlorination,  and mixed-media filtration.The
plant will be the most elaborate treatment facility in the industry  and
incorporates  a  great  many flexible concepts.  The aeration basins are
designed on a BOD:MLSS ratio of 0.3 with a total detention  time  of  18
hours.   The roughing filters are designed to remove about 60 percent of
the influent EOD5 ahead of the aeration  system.   The  design  effluent
levels  are 5 mg/1 of suspended solids and 20 mg/1 of BOD.  It should be
emphasized that these design levels are far below those which have  been
achieved  by  any  other  plant  in  the  corn  wet  milling  or related
industries and cannot yet be considered as demonstrated technology.

gludge Handling

The disposal of suspended and biological solids from  the  treatment  of
corn  wet  milling  waste waters constitutes a major problem, as it does
for any waste treatment plant handling high-strength organic  materials.
Experience  with waste activated sludge has indicated several methods of
disposal which can be  applied  to  corn  wet  milling.   These  include
dewatering  with disposal on land, incineration, or by-product recovery.
In this instance, the highly nutritious  biological  solids  potentially
provide a material that can be recycled into animal feeds.
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Limited  information  is  available  on  the handling of waste treatmen*-
plant sludges in this industry, but  it  is  know  that  several  riant?
return  these  solids to the process stream, presumably far animal f-~d.
Several tnethcds  for  accomplishing  this  can  be  suggested  including
centrifugation, vacuum filtration, and direct addition to evaporators.

It  is imperative that sanitary wastes be segregated from process waster
and discharged separately to the municipal system, if biological  sclids
recovery  from  the  process  waste  treatment plant is to be practiced.
Moreover, sterilization by heat or chlorination may be recmired in  some
instances.   In  summary,  if  the  sanitary  wastes  are separated from
process wastes, as they are at most plants, solids  from  the  treatment
system can be dewatered and/or recycled directly into the feed housc for
use in aninral feeds.


COPN DRY MILLING


Waste  waters  from  dry  corn  mills, as detailed in Section V, average
about 1,500 to 2,000 mg/1 of BOD5 and 1,500 to 3,500 mq/1  of  suspended
solids.   Flows  from  these  mills  are much smaller than from corn wet
mills, averaging some 0.00045 to 0.0013 cu m/kkg  (3 to 8 gal/MSBu) .

Treatment in the industry is thought to be very limited, as  most  mill?
discharge  to  municipal  systems.   One  known  pretreatment  plant  is
discussed in this section.

In^Plant^Controls

Waste waters can arise from only two sources in corn dry  mills,  namely
car  washing and corn washing.  The former is practiced infrequently and
at only some mills and will not be considered further.  Dry car cleaning
techniques are  now  available  using  vacuum  systems  to  replace  wet
methods.

Corn washing is performed by many, but not all, of the corn mills.  Some
mills,  because  of  the  condition  of  the  corn  as received or other
factors, feel that wet washing is not necessary.  At the mills where wet
washing is practiced, little can be done in terms of in-plant control to
improve the system.  It is possible that some mills use more water  than
is  required,  but  the  total  amounts  of  contaminants  should remain
constant.  These contaminants reflect the nature of the corn  as  it  is
received  and  little  can  be  done to reduce the total amounts.  It is
possible that partially clarified waste waters could  be  recycled  into
the corn washing operation, but this has not yet been demonstrated.

Waste_Wat.er_Treatment

Only  one  plant  is  known to provide treatment for their process waste
waters.  The treatment sequence consists  of  settling  to  recover  the
heavy  solids  for  animal  feed,  followed by a plastic media trickling
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filter and discharge to the municipal system.   Sampling data secured  at
this treatment plant are summarized below:

                                  Average   Average
                                  Influent  Effluent
                                  	mcj/1	5D2/1	

    BODS                          2,me     608
    COD"                          4,901     2,983
    Suspended Solids              3,485     1,313

Tests  run  on  settled  samples  from  this  treatment  plant indicated
additional removals of about 50 percent of the BOD5_ and  70  percent  of
the suspended solids could be achieved by secondary clarification.

The results from this pretreatment plant clearly demonstrate that wastes
from  corn  dry mills are amenable to conventional biological treatment.
It is anticipated that treatment of these wastes will be  somewhat  l«ss
difficult  than those from wet corn mills, inasmuch as lower volumes and
perhaps less exotic constituents  are  involved.   Specifically,  it  is
anticipated that sludge bulking will be less of a problem with this type
of  waste  water  than with the very high carbohydrate waste waters from
corn wet mills.

Sludge_Dis£gsal

The prevalent practice in the corn dry milling industry  is  to  recover
the  heavier  solids  from  the  wash  water for use in animal feed.  If
biological treatment of the waste waters is provided,  it  would  appear
that  waste  biological  solids  could  also be incorporated into aninral
feed,


WHEAT MILLING

Ordinary wheat milling generates little in  the  way  of  process  waste
waters  except  from  car  washing  and  wheat  washing.   Both of these
activities are not practiced at most mills and consideration will net be
given to these waste waters in this section.  Wet car and wheat  washing
systems presently in use can be replaced by dry cleaning systems.

The several plants that produce bulgur do generate limited guantities of
waste  water.   In  view  of the rather small quantities of waste water,
ranging from 38 to 114 cu m/day   (10,000  to  30,000  gpd) ,  it  is  not
anticipated that the raw waste characteristics can be greatly influenced
by  in-plant  controls.   Observations  at  one  bulgur  mill,  however„
indicated that the quantities of waste water might be  reduced  by  more
careful operational control.

All  of  the  bulgur  producers  presently  discharge  their  wastes  to
minicipal systems and no treatment of such wastes is practiced  in  this
country.   The  waste  strength,  however,  indicates  that it should be
amenable to conventional biological treatment processes.  The raw  waste
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characteristics  range from about 250 to 500 mg/1 of BOD5> and 30C tc 400
mq/1 of: suspended solids.  Effluent levels roughly equivalent  to  th^cc.
achieved  in  well-operated  secondary minicipal sewaqe treatment plant;-
should he attainable.


RICE MILLING

Ordinary rice milling involves no process waters and,  hence,  g°ncratcs
nc  process waste waters.  Six mills parboil rice, and this process dees
result in rnodest amounts of process waste waters.   These  waste  waters
are  high  in  dissolved  BOD,  approximately  1,300  ing/1,  but  low ir.
suspended solids, 30 to BO mg/1.

Tho waste water comes from the steeping process, and  in-plant  control?
cannot  be  effected  that  will  influence  appreciably thD quantity or
character of the waste waters.  At least five of the six parboiled  rice
plants  discharged  their  wastes  to  municipal  systems  and  no known
treatment is practiced by any mill.  Once again,  however,  the  general
nature of the waste water indicates that it can be treated by biological
processes  in  a  similar  manner  to corn milling or bulgur production,
inasmuch as the BOD^ is largely in a soluble form.  The rather  constar.-'-
character  of  the  waste  stream should make it more amenable to stable
treatment plant operation than corn wet milling waste waters.  Moreover,
the waste water volumes, i.e., from 265  to  760  cu  m/day  (70,000  to
200,000  gpd)  make the wastes much more manageable.  It is possible that
the biological solids frcm any treatment process could be included  with
the bran and hulls as animal feed.
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                              SECTION VIII

              COST, ENERGY, AND NON-WATER QUALITY ASPECTS
The following presents detailed cost estimates for the various treatment
alternatives and the rationale used in developing this information.

Data   have  been  developed  for  investment,  capital,  operating  and
maintenance,  depreciation,  and  energy  costs  usina  various  sources
including  information  from  individual  grain mills, Sverdrup ? Parcel
files, and literature references 21 and 22.  Generally,  the  cost  data
from  industry  relate to specific items of equipment and are of limited
utility.   Moreover,  most of the treatment systems presently  in  use  in
the  grain  milling   industry  were built over a period of years and the
cost data that is available is difficult to extrapolate and to relate to
the proposed treatment alternatives.  As a result,  the  cost  estimates
are  based  principally  on  data  developed  by  the contractor and the
references cited previously.


REPRESENTATIVE PLANTS

Because   cf   the   variations   in   plant   opeation,   waste   water
characteristics, and treatment systems, it was impractical to select one
existing  plant  as   typical of each of the grain milling subcategories.
Therefore, hypothetical  plants  were  developed  (or  synthesized)  for
purposes of developing cost data.  Each of the synthesized plants was in
the medium to moderately large production size range for the subcategory
under consideration.  Flow and waste water characteristics were selected
to  reflect  average  values  for  existing  plants  in  the industry as
reported in Section  V.


TERMINOLOGY
Investment costs are defined as the  capital  expenditures  required  to
bring  the treatment or control technology into operation.  Included, as
appropriate, are the  costs  of  excavation,  concrete,  mechanical  and
electrical  equipment installed, and piping.  An amount equal to from 1?
to 25 percent of the total of the above is added  to  cover  engineering
design services, construction supervision, and related costs.  The lower
figure  is  used  for  larger  facilities.   Because most of the control
technologies  involved  external,  end-of-plant  systems,  no  cost   is
included  for  lost  time  due to installation.  It is believed that the
interruptions required for installation of control technologies  can  be
coordinated  with normal plant operating schedules.  As noted above, the
control  facilities  are  estimated  on  the  basis  of  minimal   space
requirements.   Therefore,  no additional land, and hence no cost, would
be involved for this item.
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        Costs
The capital costs are calculated, in all cases,  as  8  percent  of  the
total  investment costs.  Consultations with representatives of industry
and the financial community  lead  to  the  conclusion  that,  with  the
limited data available, this estimate is reasonable for this industry.
Straight-line  depreciation  for  20  years,  or  5 percent of the total
investment cost, is used in all cases.

              Maintenance Costs
Operation and maintenance costs include labor,  materials,  solid  waste
disposal,  effluent monitoring, added administrative expense, taxes, and
insurance.  When the control  technology  involved  water  recycling,  a
credit of $0.30 per 1,000 gallons is applied to reduce the operation and
maintenance  costs.   Manpower  requirements  are based upon information
supplied by the representative plants  as  far  as  possible.   A  total
salary  cost  of  $10  per  man-hour is used in all cases.  The costs of
chemicals used for maintenance and operation.
           Power Costs

Power costs are estimated on the basis of $0.025 per kilowatt-hour.


COST INFORMATION

The investment and annual costs, as defined above, associated  with  the
alternative  waste  treatment control technologies are presented in this
section.  In addition, a description of each of the control technologies
is provided, together  with  the  effluent  quality  expected  from  the
application  of  these technologies.  All costs are reported in terms of
August, 1971 dollars.
Corn Wet Milling

As a basis for developing control  and  treatment  cost  information,  a
medium-sized  corn wet mill, with a daily grind of 152-4 kkg  (60,000 SBu)
was  synthesized.   This  hypothetical  plant  practices  good  in-plant
control   and   uses   recirculated  cooling  water.   The  waste  water
characteristics from the mill reflect actual industry practice based  on
average   data   received   from  existing  mills.   These  waste  water
characteristics are as follows:

    Flow                11,355 cu m/day      (3.0 mgd)
    BOD5                7.14 kg/kkg          (400 Ibs/MSBu) or 960 mg/1
    Suspended Solids    3.57                 (200 Ibs/MSBu) or 480 mg/1

A number of alternative treatment systems are  proposed  to  handle  the
waste  waters  from  this  hypothetical mill.  The investment and annual
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cost information  for  each  alternative,  and  the  resultant  efflu^n*
qualities   are   presented   in  Table  A-l.   The  specific  treatment
technologies are described in the following paragraphs.


Alternative_A — Activated Sludge

This alternative provides for  grit  removal,  pH  adjustment,  nutrien^
addition,  complete-mix  activated  sludge, secondary sedimentation, and
centrifugation for solids dewatering.  The  treatment  system  does  not
include  equalization  or  primary  sedimentation.   Effluent  EOD5  and
suspended solids concentrations are expected to be 150 to 250  mg/1  for
both  parameters.   In  terms of raw material input, the effluent values
correspond to 1.12 to 1.86 kq/kkg (63 to 104 Ibs/ MSBu).

         Ccsts.  Investment costs of approximately $2,388,000.

         Reduction Benefits.   BOD5_ and suspended  solids  reductions  of
         about 80 and 58 percent respectively.

Alt§EE<|tiye_B — Equalization and Activated Sludge

Alternative  B  includes 12 to 18 hours of aerated equalization ahead of
the complete-mix activated sludge process and associated chemical  feed,
sedimentation,  and sludge dewatering facilities proposed in Alternative
A.  Average effluent levels are estimated to be about 75 to 125 mg/1  of
both BOD5 and suspended solids.  These concentrations correspond to 0.55
to 0.91 kg/kkg (31 to 52 Ibs/ MSBu)  for both parameters.

Two  mills  now provide the general type of treatment system proposed in
this alternative.  Another similar facility provides pretreatment for  a
third mill.

         Costs.  Incremental  costs are approximately $156,000
         over Alternative A for a total cost of $2,544,000.

         Reduction Benefits.   BOD5 and suspended solids will be
         reduced by about 90  and 80 percent respectively.

Ai£§££3iive_C — Equalization, Activated Sludge, and Stabilization
                Lagoon

For  Alternative  C,  a  stabilization  basin  following secondary sedi-
mentation  is  added  to   the   preceding   treatment   system.    This
stabilization  lagoon  will provide 10-day detention for stabilizing the
remaining EOD5  and  reducing  suspended  solids.   One  mill  presently
provides a version of this treatment sequence, but without equalization.
Effluent  concentrations  of   30 to 60 mg/1 of BOD5 and suspended solids
are expected from Alternative C.  The resultant effluent waste load will
be 0.223 to 0.447 kg/kkg (12.5 to  25.0  Ibs/MSBu)  for  both  BOD5  and
suspended solids.
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         Cos-ts.  Incremental costs of approximately $288,000
         over Alternative B for a total cost of $2,832,000.

         Reduction Benefits.  BOD5 and suspended solids reductions
         of about 95 and 90 percent respectively.

Alternatj.ye_D — Equalization, Activated Sludge, and Deep Bed
                Filtration

In  this  proposed system, deep bed filtration is added to the activated
sludge system presented as Alternative B.   The  stabilization  basin  of
Alternative   C  has  been  deleted.   A  treatment  system  similar  to
Alternative D is now under  construction.    BOD5_  and  suspended  solids
concentrations  of  20  to  30  mg/1  and 10 to 20 mg/1 respectively are
expected in the effluent from this  alternative.   These  concentrations
correspond  tc  effluent  loads  of  0.15  to  0.22  kg/kkg  (8.3 to 12.5
Ibs/MSBu)  of EODJ and 0.07 to 0.15  kg/kkg  (4,2  to  8.3  Ibs/MSEu)  of
suspended solids.

         Costs.  Incremental costs of approximately $288,000 over
         Alternative B for a total cost of $2,832,000, the same
         cost as Alternative C.

         Reduction Benefits.  BOD5 and suspended solids reductions of
         about 97.4 and 96.9 percent respectively.

Alt§.rnatiye_E — Equalization, Activated Sludge, Deep Bed Filtra-
                tion and Activated Carbon Filtration

Activated  carbon  filtration  is added to the activated sludge with the
deep bed filtration system proposed  as  Alternative  D.   The  effluent
concentrations  are  estimated  to  be 5 mg/1 for both BOD and suspended
solids.  This level corresponds to a waste load  of  0.037  kg/kkg   (2.1
Ibs/MSBu)   for  both  constituents.  No treatment facility in the entire
industry provides this level of treatment.

         Costs.  Incremental costs of approximately $1,244,000
         over either Alternative C or D for a total cost of
         $4,076,000.

         Reduction Benefits.  BOD5 and suspended solids reduction
         of about 99.5 and 99.0 percent respectively.  The
         effluent should be suitable for at least partial
         recycle.

Alternative^?1 — Equalization, Activated Sludge, Deep Bed Filtra-
     ~          tion, Activated carbon Filtration, and Reverse
                Osmosis

This alternative includes reverse osmosis to reduce the total  dissolved
solids.    Effluent   levels  will  be  comparable  to  those  given  in
Alternative E, but with a maximum dissolved solids content of 500 mg/1.
                                 80

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         Costs.  Incremental costs of approximately $1,884,000
         over Alternative E for a total cost of $5,960,000.

         Reduction Benefits.  BOD.5 and suspended solids reductions
         equal to those in Alternative E, i.e., 99.5 and 99.0
         percent respectively.  The effluent should be suitable
         fcr complete recycle.

              — Recirculatinq Cooling Water System
The synthesized corn wet mill described previously is  assumed  to  have
good  in-plant  water  conservation  practices  including  recirculatinq
cooling  water  systems.   comparably  sized  mills  using  once- through
cooling waters will be confronted with the additional cost of installinot
cooling  towers  to reduce total waste water flows.  A separate cost hots
been developed for such plants based on a  recirculai-ing  cooling  water
demand of about 34,000 cu m/day (9.0 mgd or 6250 gpm) .

         Ccst.    Incremental  costs  of  adding  a  cooling  tower  are
         approximately $288,000.

Cgrn_Dry
A hypothetical corn dry mill of moderate to large size, i.e. 762 kkg/day
 (30,000 SBu/day) , was selected as a basis  for  developing  costs  data.
This  synthesized  plant  generates  a  waste water that reflects actual
industry practice as follows:

    Flow                492 cu m/day        (130,000 gpd)
    BOD5                1.13 kg/kkg         (63 Ibs/MSBu) or 1750 mg/1)
    Suspended solids    1.61 kg/kkg          (90 Ibs/MSBu) or  2500 mg/1)

            A "" Primary Sedimentation
This alternative consists only of primary sedimentation and reduces  the
BOD5 and suspended solids to about 1,000 mg/1 and 500 mg/1 respectively.
These  concentrations  correspond to effluent waste loads of 0.65 kg/kkg
(36 Ibs/MSBu)  of BOD5 and  0.32  kg/kkg  (18  Ibs/  MSBu)  of  suspended
sclids.   Presumably some corn dry mills have clarifiers similar to that
provided for Alternative A.

         Cost.  Investment costs of approximately $20,000.

         Reduction Benefits.   BOD5_ and suspended solids reductions
         of about 43 and 80 percent respectively.

            B — Primary Sedimentation and Activated Sludge
Alternative  B  includes  primary  sedimentation,   nutrient   addition,
complete-mix  activated  sludge,  secondary  sedimentation,  and  sludge
dewatering.  Expected effluent levels are 100 mg/1 of BOD5 and suspended
solids corresponding to a  treated  waste  load  of  0.065  kg/kkg   (3,6
Ibs/MSBu)  fcr both pollutant parameters.
                                 81

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         Costs.  Incremental costs of approximately $271,000 over
         Alternative A for a total cost of $291,000,

         Reduction  Benefit.   BOD5  and  suspended solids reductions of
         about 94.3 and 96.0 percent respectively.

              —• Primary Sedimentation, Activated Sludge, and
                Stabilization Lagoon

This alternative adds a 10-day stabilization lagoon in series  with  the
activated  sludge system as given in Alternative B.  Effluent quality is
expected to be 30 to 60 mg/1 of BOD5 and suspended solids or an effluent
waste load of 0.019 to 0.039 kg/kkg  (1.1 to  2.2  Ibs/  MSBu)  for  both
constituents.

         Costs.  Incremental costs of approximately $25,000 over
         Alternative B for a total cost of $316,000.

         Reduction Benefit.  EOD5 and suspended solids reductions
         of about 97.4 and 98.2 percent respectively.

^iij§££^iiYS_2 "*~ Primary Sedimentation, Activated Sludge, and
                Deep Bed Filtration

Deep bed filtration following the activated sludge system comprises this
alternative.   The  concentration  of  BODjj  and suspended solids in the
treated effluent is expected to be 20 to 30  mg/1  and  10  to  20  mg/1
respectively.   These  effluent  concentrations  are equivalent to waste
loads of 0.013 to 0.019 kg/kkg (0.7 to 1.1 Ibs/MSBu) of EOD5  and  0.006
to 0.013 kg/kkg  (0.36 to 0.7 Ibs/MSBu) of suspended solids.

         Costs.  Incremental costs of approximately $32,000 over
         Alternative B for a total cost of $323,000.

         Reduction Benefit.  BOD^ and suspended solids reductions
         cf about 98.6 and 99.4 percent respectively.

A.itSJU^iy.fL.I; — Primary Sedimentation, Activated Sludge, Deep Bed
                Filtration, and Activated Carbon Filtration

The  final alternative presented herein adds acitvated carbon filtration
to the activated sludge - deep bed filtration  system  of  the  previous
alternative.   Treated effluent quality is expected to be 5 mg/1 of both
EOD.5 and suspended solids for an equivalent waste load of  0.003  kg/kkg
 (0.18 Ibs/MSBu).

         Costs.  Incremental costs of $174,000 over Alternative
         D for a total cost of $497,000.

         Reduction Benefit.  BOD^ and suspended solids reductions
         of about 99.7 and 99.8 percent respectively
                                  82

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Vvhea^_Milling  (Bulgur)

Inasmuch  as  ordinary  wheat milling usually generates no process v;aste
waters, this discussion will  be  limited  to  bulgur  production.   Thr
synthesized  bulgur  mill  is of medium size, 203 kkg/day  (8000 Sbu/day)
and discharges waste waters with the following characteristics:

    Flow                56.7 cu m/day             (15,000 gpd)
    BOD5                0.104 kg/kkg              (6.25 Ibs/MSBu) or 400 in/1
    Suspended Solids    0.093 kg/kkg              (5.62 Ibs/MSBu) or 360 mg/1

Alternatiye_A — Activated Sludge

The first alternative provides an activated sludge   (extended  aeration)
system  with  nutrient addition and secondary sedimentation.  No primary
sedimentation is provided because of the low  flows.   Moreover,  it  is
anticipated  that  factory  built or so-called package treatment systems
can be used.  Sludge will be hauled away several times a year  for  land
disposal.   The  treated  effluent  quality is expected to be 30 mg/1 of
both BODJ and suspended solids  corresponding  to  0.0078  kg/kkg  (0.47
Ibs/MSBu) .

         Costs.  Investment costs of approximately $24,000.

         Reduction Benefit.  BOD5 and suspended solids reductions
         of about 92.5 and 91.7 respectively.

Alternative_B — Activated Sludge and Deep Bed Filtration

This  alternative  adds  deep bed filtration to activated sludge system.
The filtered effluent is expected to contain 10 to 20 mg/1 of BOD5 and 5
to 10 mg/1 cf suspended solids.  The corresponding effluent waste  loads
are  0.0027  to 0.0052 kg/kkg  (0.16 to 0.31 Ibs/MSBu) of BOD5 and 0.0013
to 0.0027 kg/kkg (0.08 to 0.16 Ibs/MSBu)  of suspended solids.

         Costs.  Incremental costs of approximately $69,000 over
         Alternative A for a total cost of $93,000.

         Reduction Benefit.  BOD5 and suspended solids reductions
         of about 96.2 and 97.8 percent respectively.

Alternatiye_C — Activated Sludge, Deep Bed Filtration, and Activated
                Carbon Filtration

This final alternative incorporates activated  carbon  filtration  as  a
final  polishing  step  after  Alternative  B.   The  treatment effluent
quality is expected to be 5 mg/1 of both BOD^ and suspended solids cr an
effluent waste load of 0.0013 kg/kkg (0.08 Ibs/MSBu).

         Costs.  Incremental costs of approximately $287,000 over
         Alternative E for a total cost of $380,000.

         Reduction Benefit.  BODj> and suspended solids reductions
         cf about 98.8 and 98.6 respectively.
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R.ice_Millinc[
This discussion will be limited to parboiled rice milling since ordinary
rice milling generates no process waste waters.  The  hypothetical  rice
mill  selected  for  developing  cost  data  is a moderately large plant
processing 363 kg/day  (8000 cwt/day) .  Raw waste  water  characteristics
are:
Flow
BOB5
Suspended Solids
492 cu m/day
1.88 kg/kkg
0.075 kg/kkg
                                       (130,000 gpd)
                                       (0.188 Ibs/cwt)  or 1380 mg/1
                                       (0.0075 Ibs/cwt)  or 55 mg/1
              — Activated Sludge
The first treatment alternative provides nutrient addition, complete mix
activated sludge and secondary sedimentation.  Waste activated sludge is
dewatered  by  a  centrifuge  and mixed with the millteed  (animal feed)  .
Treated waste water concentrations of 100 mg/1 of BOD and 60 to 80  mg/1
of  suspended  solids are expected.  These effluent levels correspond to
waste loads of 0.14 kg/kkg (0.014 Ibs/cwt)  of  BOD5  and  0.08  to  0.11
kg/kkg (0.008 to 0.011 Ibs/cwt) of suspended solids.

         Costs.  Investment costs of approximately $313,000.

         Reduction Benefit.  BODJ5 reductions of about 92.8 percent.

£i£ernatiye_B — Activated Sludge and Stabilization Lagoon

This  alternative  merely  adds  a  10-day  stabilization  lagoon to the
activated sludge system of Alternative A  to  effect  greater  BODj>  and
suspended  solids  removals.  The effluent quality from Alternative B is
expected to be 30 to  60  mg/1  of  BOD5  and  suspended  solids  or  an
equivalent waste load of 0.041 to 0.081 kg/kkg  (0.004 to 0.008 Ibs/cwt).

         Costs.  Incremental costs of approximately $35,000 over
         Alternative A for a total cost of $348,000.

         Reduction Benefit.  BOD5_ reduction of about 96.7 percent.

Alternative_C — Activated Sludge and Deep Bed Filtration

Alternative  C  consists  of  the  activated  sludge  system proposed in
Alternative A followed by deep bed filtration.   The  concentrations  of
BOD5  and  suspended  solids in the effluent are expected to be 20 to 30
mg/1 and 5 to 10 mg/1 respectively.  These concentrations  correspond  to
effluent waste loads of 0.027 to 0.041 kg/kkg  (0.0027 to 0.0041 Ibs/cwt)
of  BOD5_  and  0.007  to  0.014  kg/kkg  (0.0007  to  0.0014 Ibs/cwt) of
suspended solids.

         Costs.  Incremental costs of approximately $34,000 over
         Alternative A for a total cost of $347,000.
                                 84

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         Reduction Benefit.  BOD5 and suspended solids reductions
         of about 98.2 and 86.U percent respectively.

Alternative_D — Activated Sludge, Deep Bed Filtration, and Acti-
                vated Carbon Filtration

In this last alternative, activated carbon is  added  to  the  activated
sludge  and  deep  bed  filtration  treatment  system.  Treated effluent
quality is expected to be 5 mg/1 of both BOD5 and suspended solids cr an
effluent waste load of 0.007 kg/kkg (0.0007 Ibs/cwt).

         Costs.  Incremental costs of approximately $181,000 over
         Alternative C for a total cost of $528,000.

         Reduction Benefit.  BOD5_ and suspended solids reductions
         of about 99.6 and 90.9 percent respectively.


NON-WATER QUALITY ASPECTS OF TREATMENT AND CONTROL TFCHNOLOGIES

Air_Pcllution_Contrgl

With the proper operation of the types of biological  treatment  systems
presented earlier in this section, no significant air pollution problems
should  develop.  Since the waste waters from the grain milling industry
have a high organic content, however, there is always the potential  for
odors.   At  least  one  present  treatment plant has experienced rather
severe odcr problems from a sludge lagoon.  Care should be taken in  the
selection,  design,  and  operation  of  biological treatment systems to
prevent  anaerobic  conditions  and  thereby  eliminate  possible   odor
problems.

Solid^Waste^Disposal

The  treatment  of  grain  milling  waste  waters will give rise to sub-
stantial quantities of solid wastes, particularly biological solids from
activated sludge or comparable systems.  Several avenues  are  available
for  the  disposal  of  these  solids  including digestion and landfill,
incineration, and other  conventional  methods  fo  handling  biological
solids.   Alternately,  the  solids  can  be  dewatered and added to the
animal feed already being produced at these mills.   This  practice  has
found  some acceptance in the grain milling industry, particulary in the
corn wet milling  segment,  and  is  strongly  recommended.   Additional
discussion  of  solids  recovery  and  sludge  disposal  is contained in
Section VII.

l£s rgy._R eg u ir emen t s

The treatment technologies presently in use or proposed in this document
do not require any processes with unusually  high  energy  requirements.
Power  will be required for aeration,  pumping, centrifugation, and ether
unit operations.  These requirements,  generally are a direct function of
the volume to be treated.  Thus, the greatest requirements  will  be  in
                                85

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the  corn  wet  milling  subcategory and the least in bulgur waste water
treatment.

For the hypothetical treatment  systems  described  previously  in  this
section,  the  power requirements are in the range of 375 to 450 kw (500
to 600 hp).  This level of demand is small relative to the  requirements
for  the  entire  mill.   Similar projections in the other grain milling
subcategories  lead  to  the  conclusions  that  the  energy  needs  for
achieving  good waste water treatment constitute only a small portion of
the energy demands of the industry.   These added demands can readily  be
accomodated.
                                 86

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                               SECTION IX

        EFFLUENT REDUCTION ATTAINABLE THROUGH THE APPLICATION OF
      THE EEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY AVAILABLE
                    EFFLUENT LIMITATIONS GUIDELINES

INTRODUCTION

The  effluent  limitations  that  must  be  achieved July I, 1977 are to
specify  the  degree  of  effluent  reduction  attainable  through   the
application   of  the  best  practicable  control  technology  currently
available.  The best practicable control technology currently  available
is generally based upon the averages of the best existing performance by
plants  of various sizes, ages, and unit processes within the industrial
category or subcategory.  This average is not based on a broad range  of
plants  within  the  grain  milling  industry, but on performance levels
achieved  by  a  combination  of  plants  showing   exemplary   in^hcuse
performance and those with exemplary end-of-pipe control technology.

Consideration must also be given to:

    a.   The total cost of application of technology in relation
         tc the effluent reduction benefits to be achieved from
         such application;
    b.   the size and age of equipment and facilities involved;
    c.   the processes employed and product mix;
    d.   the engineering aspects of the application of various types
         of ccntrol techniques;
    e.   process changes; and
    f.   non-water 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 reliatility
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  engi-*
neering  and  economic  practicability  of the technology at the time of
commencement cf construction or installation of the control facilities.


EFFLUENT REDUCTION  ATTAINABLE  THROUGH  THE  APPLICATION  OF  THE  EEST
PRACTICABLE CCNTROL TECHNOLOGY CURRENTLY AVAILABLE

Based  on the information presented in Sections III through VIII of this
report, it has been determined that the effluent  reductions  attainable
through  the  application  of  the  best  practicable control technology
currently available are those  presented  in  Table  15.   These  values
represent  the  maximum average allowable loading for any 30 consecutive
calendar days.  Excursions above these levels should be permitted with a
                                 87

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maximum daily average of 3.0 times  the  average  30-day  values  listed
below.

                                Table 15

        Effluent Reduction Attainable Through the Application of
        Best Practicable Control Technology Currently Available*
Industry Category
and Subcategory
            i 	I

Corn wet rrilling
Corn dry irilling
Normal wheat flour
  milling
Eulgur wheat flour
  milling
Normal rice milling
Parboiled rice milling
              BOD5
        kc[/kkg   Ib
                          Suspended Solids
        0.893
        0.071
              50.0
               4.0
                  0.625
                  0.062
35.0
 3.5
6-9
6-9
             No discharge of process waste waters
        0.0038      0.5       0.0083       0.5    6-9
             No discharge of process waste waters
        0.140       0.014     0.080        0.008  6-9
^Maximum average of daily values for any period of 30 consecutive days
IDENTIFICATION
AVAILABLE
OF
BEST
PRACTICABLE  CONTROL  TECHNOLOGY  CURRENTLY
The best practicable control  technology  currently  available  for  the
grain  milling  industry  generally  consists  of  a high level of waste
treatment coupled,  in  some  instances,  with  certain  in-plant  modi-
fications.   The specific technological means available to implement the
specified effluent limitations are presented below for each subcategory.

Corn Wet_Milling

The corn wet milling segment of the grain milling industry  must  under-
take  major pollution abatement activities in order to meet the effluent
limitations.  These activities will include both in-plant  modifications
and biological waste water treatment as follows:

    1.   Isolating and collecting the major waste streams for
         treatment.

    2.   Eliminating once-through barometric cooling waters, espe-
         cially from the steepwater and syrup evaporators.  This
         change can be accomplished by recirculating these cooling
         waters over cooling towers or replacing the barometric
         condensers with surface condensers.

    3.   Isolating once-through noncontact  (uncontaminated) cooling
         waters for discharge directly to the receiving waters or
         provision of recirculating cooling tower systems with the
         blowdown directed to the treatment plant.
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    U.   Diking of all process areas subject to frequent spills in
         order to retain lost product for possible reuse or by-
         product recovery.

    5.   Installing and maintaining modern entrainment separators
         in steepwater and syrup evaporators.

    6.   Monitoring the major waste streams to identify and control
         sources of heavy product losses.

    7.   Providing extensive waste treatment for the resulting
         process waste waters consisting of:  flow and quality
         equalization, neutralization, biological treatment, and
         solids separation.  The biolcgical treatment methods
         available include activated sludge, pure oxygen acti-
         vated sludge, bio-discs, and possible combinations of
         ether biological systems.


Corn_Dry_Milling

Waste  waters  from  corn  dry mills are generated almost exclusively in
corn washing.  Little can be done to reduce  the  waste  load  from  the
plant  and  treatment  of  the  entire waste stream will be necessary as
follows:

    1.   Collection of waste waters from car washing operations,
         where practiced.

    2.   Primary solids separation by sedimentation.

    3.   Biolcgical treatment using activated sludge or a com-
         parable system.

    4.   Final separation of solids by sedimentation prior to
         discharge.
The effluent limitation for the milling of ordinary wheat flour  permits
no  discharge  of process wastes.  Inasmuch as most ordinary wheat mills
do not use process waters, this effluent limitation can be met  with  no
plant  changes.   For  the  few  mills that wash the wheat, dry cleaning
systems are available to eliminate this waste source.

Bulgur wheat milling generates a relatively small  quantity  of  process
waste  water that will require treatment to meet the effluent standards.
Such treatment will include:

    1.   Primary solids separation by sedimentation.

    2.   Biolcgical treatment using activated  sludge  or  a  comparable
         system.
                                   89

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    3,   Final separation of solids by sedimentation prior to discharge.

Pice._Milling

Normal rice milling involves no process waters and, hence, the  effluent
limitation  of no discharge of process wastes is already being met.  The
few mills producing parboiled rice generate a relatively small amount of
high  strength  process  waste  water.   The  best  practicable  control
technology  currently available for the parboiled rice subcategory is as
follows:

    1.   Biological treatment using activated sludge or
         comparable systems.

    2.   Final separation of solids by sedimentation prior
         tc discharge.


RATIONALE FOR THE  SELECTION  OF  BEST  PRACTICABLE  CONTROL  TECHNGIOGY
CURRENTLY AVAILABLE

Ccrn_Wet_Milling

Cost_gf_Ap_Elication-

Data  developed  on  the ccst of applying various treatment technologies
are presented in Section VIII.  For a 1524 kkg   (60,000  SBu)  corn  wet-
mill,  the investment cost for implementing the best practicable control
technology currently available is about  $2,544,000,  exclusive  of  the
costs  for  in-plant  control.   Additional information on operating and
maintenance costs is contained in section VIII.

Age_and_Size_of_Productign_Faci].ities^

The mills in this subcategory range in age from two to  over  60  years.
The  chronological  age  of  the  original  buildings, however, does not
accurately  reflect  the  degree  of  modernization  of  the  production
facilities.   In  order  to  meet  changing  market  demands  and strong
competition,  most  mills  have  actively   developed   new   production
techniques.   As  a result, it is difficult to differentiate between the
basic production operations at the various plants based on  age,  except
perhaps for the newest two or three mills.

Similarly, waste water characteristics from the corn wet mills cannot be
classified  according  to  plant  age.  While several of the newer mills
generate low raw waste loads in terms of BOD5 and suspended  solids,  at
least one of the newer mills yields raw waste loads near the high end of
the spectrum.  Conversely, several older mills have low raw waste leads.
The  comparison  of  age  versus  raw  waste load presented in Section  V
clearly demonstrates the absence of any correlation based on plant  age.
Accordingly,  the  age of the mill is not a direct  factor in determining
the best practicable control technology currently available. Indirectly,
the age of the plant as it may be  reflected  in  equipment  layout  may
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place  some restraints on the ability of a particular plant to implement
seme recommended in-plant changes.

The size of the mill has a direct influence  on  the  total  amounts  of
contaminants  discharged.   In general, the larger the plant the greater
the waste load.  The effluent limitations  presented  herein  have  been
developed  in  terms  of  unit  of  raw  material input, i.e., kg/kkg or
Ibs/MSBu, in crder to reflect the effect of  plant  size.   The  control
technologies  discussed  in  Section VII, however, are applicable to all
mills regardless of size.
The basic processes employed in corn wet mills are  essentially  uniform
throughout  this  segment  of the industry.  From corn unloading through
basic starch separation,  the  production  methods  are  quite  standard
although  slightly  different  types  of  equipment  may  be used at the
various mills.

!£2<3uct_Mix-

The product mix at a given plant  varies  significantly  on  a  monthly,
weekly,   and   even   daily   basis.    As  a  result,  the  raw  waste
characteristics at the plant may vary widely.  Certain  highly  modified
starches, for example, will result in higher waste loads per unit of raw
material.   In  spite  of the recognized influence of product mix on the
raw waste characteristics of a given plant, no relationship between  the
raw  waste  characteristics from all the mills and their product mix can
be distinguished based on available data,  as  previously  discussed  in
Section V.

Thus,  while consideration was given to the variability of the raw waste
characteristics in developing the specified effluent  limitations,  this
variability could not be quantitatively defined in terms of product mix.
Moreover,  there  is  no  evidence to suggest that waste waters from any
specific process so affect the character of the total plant waste stream
as to substantially reduce the ability of the mill to implement the best
practical control technology currently available.
The engineering feasibility of achieving the effluent limitations  using
the  technology  discussed  has been examined.  Each of the in-plant and
treatment control technologies presented are being used by one  or  more
corn  wet  mills, although not necessarily in combination.  Furthermore,
each of these control steps effectively reduces the waste volume or  the
total  waste  load,   or  improves  the  quality of the treated effluent.
Several of the control measures result in the  isolation  and  resultant
concentration  of  the process wastes into a smaller volume suitable for
more economical treatment.  Such practices have  been  in  effect  in  a
number  of  mills  for  several  years.  Once-through barometric cooling
waters  are  of  particular  importance  in  this  regard  because  they
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represent  a  high  volume  waste  with  low concentrations of pollutant
constituents.

In-plant housekeeping and good operation can have a major impact on  the
raw  waste  leads  from  a mill.   Diking of spill areas, monitoring, and
careful operation have been reported to reduce raw waste loads by 25  to
50 percent in some plants.

Treatment  of  corn  wet  milling wastes with activated sludge and ether
biological systems has been demonstrated at seven mills as  detailed  in
Section  VII.    Although  treatment  plant  upsets  do occur, a properly
designed and operated  system  should  be  able  to  meet  the  effluent
limitations  developed  in  this   document.  At least one mill presently
meets these  effluent  limitations  using  an  activated  sludge  system
followed  by aerated lagoons.  While this system includes one additional
treatment step, the plant does not presently recirculate all  barometric
cooling water, a suggested control procedure.

The   combination  of  in-plant  controls  and  proper  waste  treatment
constitutes a practicable means  for  achieving  the  specific  effluent
limitations.   On  an overall industry basis, these effluent limitations
will result in a BODJ5 reduction of approximately 85 to 90 percent and 85
percent reduction of suspended solids.

The concentrations of contaminants in the waste waters from plants using
once-through barometric cooling  water  are  in  the  moderate  strength
range,  i.e.,   approximately 250  to 450 mg/1 of BOD5 and 100 to UOO mg/1
of suspended solids, as shown in  Table 10.  These wastes  are  generally
slightly  stronger  than  normal   domestic  sewage,  but  the  secondary
effluent limitations that have been  established  for  municipal  plants
should  be  achievable  by  the  proper  treatment  of these wastes.  In
establishing the effluent reduction attainable, as  presented  in  Table
15, therefore, an effluent level  of 30 mg/1 of both suspended solids and
EOD5 was selected for the plants  using once-through contaminated cooling
water.   The  levels established  in Table 15 are equivalent to estimated
effluent concentrations of 20 to  30 mg/1 for such plants.

Many plants isolate the major process water sources and use recirculated
cooling water systems.  The effluent  waste  concentrations,  therefore,
are  much  higher  than  for those plant using once-through contaminated
cooling waters.  Raw wastes from  these plants contain from 600  to  U500
mg/1  of  EOD5  and  300  to  2500  mg/1  of suspended solids.  The best
practicable  control  technology    currently   available   will   effect
approximately an 85 to 90 percent reduction in BOD.5 and suspended solids
for  these  concentrated wastes.   Effluent concentrations of 100 mg/1 of
BOD^ and 75 mg/1 of suspended solids are selected as general goals to be
achieved by the effluent limitation guidelines.  The 30 mg/1  goal  that
was  applied to dilute corn wet milling wastes cannot be achieved by the
proposed technologies for these highly concentrated waste streams.   The
effluent  limitation  guidelines   proposed  in  Table  15 will result in
estimated effluent concentrations of 50 to 200 mg/1 of BODJ5  and  35  to
140  mg/1  of  suspended  solids.  The higher values of these ranges are
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generally for new plants  that  practice  maximum  water  recycling  and
produce highly concentrated waste steams of 3000 mg/1 or higher.

Eased  on  present  waste  water volumes in the industry, therefore, the
average treated effluent resulting from these effluent limitations  will
contain  about  50  mg/1 of BOD.  For those plants presently using once-
through barometric cooling water, the  effluent  quality  based  on  the
present  total waste water flow will be on the order of 20 to 30 mg/1 of
BOD.  For those mills that utilize recirculating cooling  water  systems
and  have  concentrated raw waste streams, the effluent limitations vvill
require an effluent quality of approximately 100 mg/1  of  BOD5  and  75
mg/1 of suspended solids.
The  application of this control technology may require modifications to
certain process equipment, but the basic process will remain  unchanged.
Some  of  the in-plant control measures have already been implemented at
some mills.
~Lr\ terms of the non-water quality environmental impact, the only item of
possible concern is the increased  energy  consumption  to  operate  the
treatment  plant.   Relative  to the production plant energy needs, this
added load is small and not of significant  impact.   For  example,  the
power  requirements  for the application of the best practicable control
technology currently available to a  medium  sized  corn  wet  mill  are
estimated  to be U50 kilowatts (600 hp) .  This demand represents a small
percentage of the mill's total power usage.

Corn prY_Milling

Cos t _o f _ A_g£l i cat ion -

The investment costs for implementing various control technologies  were
presented  in  Section VII.  These costs were estimated for a moderately
large corn dry mill to be $291,000.

Plant _Age ^ Size_and Product ion Methods^

The only source of process waste waters in corn dry mills is the washing
operation.  Some  mills  do  not  wash  the  incoming  corn,  apparently
reflecting  a  cleaner raw material or, possibly, less stringent quality
control practices.  Based on the limited data available, no  correlation
can  be  established  between  the  raw  waste  characteristics and such
factors as plant age, size, or production methods.   Equally  important,
these   factors   do  not  affect  the  ability  to  apply  the  control
technologies presented earlier in the section.

                   _gf _Ap_p_licati.on-
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Few, if any, corn dry mills provide extensive waste water treatment with
discharge directly  to  the  receiving  waters.    The  best  practicable
control  technology  currently  available  does   not  represent practice
achieved by any corn dry mill.  Rather,  this  technology  reflects  the
transfer  of treatment practice demonstrated on  other high strength food
processing wastes.  Data from one pretreatment plant clearly  show  that
this  type  of  waste  water  is  amenable  to  biological treatment and
suspended  solids  removal.   Accordingly,  the    treatment   technology
recommended  is  considered  to  be  quite  practicable.   The raw waste
characteristics for corn dry mills indicated a BOD5_ of 600 to 2700  mg/1
and a suspended solids level of 1000 to 3500 mg/1, as shown in Table 12.
The best practicable control technology currently available will provide
approximately  90 percent reduction of the strength of these wastes.  An
effluent concentration of about 100 mg/1 for  both  BOD5_  and  suspended
solids  was  considered  a practical goal and was used in developing the
data given in Table 15.  Estimated average effluent  levels  achievable,
using the proposed effluent limitation guidelines, are about 105 mg/1 of
BOD5  and  90  mg/1  of  suspended  solids.   Based  on limited data for
existing plants, the BOD^ is expected to be between 80 and 150 mg/1, and
suspended solids, between 70  and  115  mg/1.   The  treatment  achieved
represents  90  to 95 percent removal of both BOD5_ and suspended solids,
Activated sludge or comparable biological treatment will  achieve  about
90  to  95  percent  BODjS  and  suspended  solids reductions.  The final
effluent concentrations to be realized by applying the specified control
technologies will be about 100 mg/1 of BOD5 and suspended solids.
The  non-water  quality  environmental  impact  is  restricted  to   the
increased  power  consumption required for the treatment facility.  This
power  consumption  is  quite  small  compared  to  the   total   energy
requirements  for  a  corn  dry  mill  and, therefore, the impact of the
control facilities is considered insignificant.

Wheat Milling

The only process waste water in wheat milling arises from the  tempering
operations  used  in  bulgur  flour  production.   No correlation can be
established between the raw waste characteristics or  ability  to  apply
the  specified  control  technologies  and  such factors as plant age or
size, production methods, and raw material quality.  No bulgur  mill  is
known  to  provide  waste  water  treatment at this time.  The treatment
technology defined previously, however, represents practice  in  related
areas  of food processing.  Waste water from bulgur production should be
amenable tc solids  separation  and  biological  treatment.   The  waste
strength  is somewhat higher than normal sanitary sewage, but well below
the high levels common in the other milling categories.   As  a  result,
treatment  to  effluent  levels  of  about 30 mg/1 of BOD5_ and suspended
solids is practicable and will be achieved by the  effluent  limitations
presented  in  Table  15.   Approximately  90 percent BOD5 and suspended
solids reductions will result.  The investment costs to provide the best
practicable control for a medium sized bulgur plant  were  estimated  in
Section VIII to be $24,000.
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Non-water  quality  environmental  impact  will be restricted to a sirall
increase in power consumption for  the  treatment  plant.   These  power
needs are irinimal and not of major significance.

Rice_M i JL1 i ng

Waste  waters  from  the production of parboiled rice represent the only
source of process waste waters in rice milling.  The characteristics  of
this  high-strength soluble BOD5 waste cannot be related to plant age or
size, production  methods,  or """raw  material  quality.   Likewise,  the
applicability  of the specified control technologies is not dependent on
any of these factors.

At present, no rice mill in the country provides waste water  treatment.
The  best practicable control technology currently available, therefore,
represents the transfer of treatment practice from other food processing
industries.  Pilot plant studies have demonstrated  that  the  waste  is
amenable  to biological waste treatment.  Raw wastes from parboiled rice
milling contain a high level of BOD, approximately 1,300 mg/1, as  shown
in  Table  14,  but a low level of suspended solids.  Treatment of these
wastes,  using  the  best  practicable  control   technology   currently
available, will achieve about a 90 to 95 percent reduction of BOD.  Once
again,  an  effluent  BOD5  concentration  of 100 mg/1 was selected as a
practical gcal.  The suspended solids level  that  has  been  specified,
represents  about  80  mg/1,  almost  all  of which represent biological
solids produced in the activated  sludge  system.   Thus,  the  effluent
suspended  solids show no appreciable decrease, although their character
has changed through the biological treatment sequence.  In essence,  the
effluent  suspended  solids  level  is dictated by the type of treatment
technology applied as opposed to the influent suspended  solids  levels.
Estimated  effluent  BODE>  levels for two plants are 80 to 130 mg/1 with
suspended solids levels of 50 to  75  mg/1.   The  effluent  limitations
given  in  Table  15 will achieve about 90 to 95 percent BOD5_ reductions
and result in a treated waste water containing about 100  mg/1  of  EODj>
and  80  mg/1  of  suspended  solids.  As presented in Section VIII, the
investment cost to provide this level of control for a moderately  large
plant will be about $313,000.

Non-water  quality  environmental  impact  will be restricted to a small
increase in power consumption to operate the treatment plant.


RESTRAINTS ON THE USE OF EFFLUENT LIMITATIONS GUIDELINES

The effluent limitation guidelines  presented  above  can  generally  be
applied   to  all  plants  in  each  grain  milling  category.   Special
circumstances  in  individual  plants,  however,  may  warrant   careful
evaluation, especially in corn wet milling.

Corn  wet mills are, by their very nature, sophisticated chemical plants
producing  a  variety  of  products.   Raw  waste  characteristics   are
dependent  en  many  factors, not the least of which is product mix.  It
must be emphasized that, even with the implementation  of  the  in-plant
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controls  detailed earlier in this section, some plants will not be able
to reduce their raw waste loads per unit of raw material  input  to  the
same low levels achieved by other mills.

Isolating  all  major  process waste streams in some of the older plants
may be very difficult and expensive.  A similar situation may  exist  in
the  case  of  sanitary sewers.  The discharge of sanitary wastes to the
treatment plant will not adversely affect the treatment process, but  it
will  eliminate the possibility of using waste solids from the treatment
plant in feed preparations.  Alternative solids  disposal  methods  will
have to be selected in such cases.

Conversion  of  barometric condensers to surface condensers is suggested
as one means of concentrating waste streams, but such conversion is  not
without  seine  problems.   Specifically,  surface  condensers  are  more
expensive than barometric  units  and  they  require  considerably  more
maintenance.   In  some  plants,  existing  equipment  layouts  prohibit.
conversion  to  surface  condensers.   Some  mills   have   found   that
recirculation  of  barometric  cooling waters over cooling towers can be
readily accomplished and provide results that are comparable in terms of
pollutant constituent levels in the waste stream.

Finally, it must be recognized  that  the  treatment  of  high  strength
carbohydrate  wastes  is  difficult.   Upset  conditions  may occur that
result in higher BODJ5  and  suspended  solids  discharges  than  normal.
While the in-plant modifications and controls and the treatment sequence
defined  as best practicable control technology currently available will
minimize these upsets, they may still occur.   However,  the  limitation
described  above  make  adequate  allowances  for this possibility.  The
maximum daily average  is  three  times  the  maximum  allowable  30-day
limitation for both BODJ5 and suspended solids.  However, the limitations
described  above  make  adequate  allowances  for this possibility.  The
maximum daily average is  three  times  the  maximum  allowable  30  day
limitations for both BOD5 and suspended solids.

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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  that  must  be  achieved July 1, 1983 are to
specify  the  degree  of  effluent  reduction  attainable  through   the
application  of  the  best available technology economically achievable.
This control technology is  not  based  upon  an  average  of  the  best
performance   within  an  industrial  category,  but  is  determined  by
identifying the very best control and treatment technology employed by a
specific plant within the industrial category or subcategory, or readily
transferable from one industry process to another.

Consideration must also be given to:

    a.   The total cost of application of this control technology
         in relation to the effluent reduction benefits to be
         achieved from such application;
    b.   the size and age of equipment and facilities involved;
    c.   the processes employed;
    d.   the engineering aspects of the application of this control
         technology;
    e.   process changes; and
    f.   non-water quality environmental impact (including energy
         requirements).

Best available technology economically  achievable  also  considers  the
availability  of  in-process  controls as well as end-of-process control
and additional treatment techniques.  This  control  technology  is  the
highest  degree  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 ccsts
for 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,  this  control  technology  may  be
characterized  by  some  technical  risk with respect to performance and
with respect to certainty of costs.  Therefore, this control  technology
may  necessitate  some  industrially sponsored development work prior to
its application.


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

Based  on the information contained in Sections III through VIII of this
document, it has been determined that the effluent reductions attainable
through the application of the best  available  technology  economically
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achievable  are those presented in Table 16.   These values represent the
maximum average allowable loading for any 30  consecutive calendar  days.
Excursions  above  these levels should be permitted with a maximum daily
average of 3.0 times the average 30-day values listed below.

                                Table 16

        Effluent Reduction Attainable Through the Application of
           Best Available Technology Economically Achievable
Industry
      BOD5
           Suspended Solids
                      pH
Corn wet milling
Corn dry milling
Normal wheat flour
  milling
Eulgur wheat flour
  milling
Normal rice milling
Parboiled rice milling
0.357
0.0357
20
 2.0
0.179
0.0179
10
 1.0
6-9
6-9
      No discharge of process waste waters

0.0050       0.3      0.0033      0.2     6-9
      No discharge of process waste waters
0.070        0.007    0.030       0.003   6-9
*Maximum average of daily values for any period of 30 consecutive days


IDENTIFICATION OF BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE

For all of  the  segments  of  the  grain  milling  industry,  the  best
available  technology  economically achievable comprises improved solids
separation  following  activated   sludge   or   comparable   biological
treatment.   Improved  solids separation can be represented best by deep
bed filtration although alternative systems may  be  available.   It  is
anticipated  that  the  technology  of  removing  biological  solids  by
filtration will improve rapidly with the increased use of such treatment
processes in many industries and municipalities.


In the corn wet milling subcategory,  a  combination  of  end-of-process
treatment,  as  described above, and in-plant controls will be necessary
to meet these  effluent  limitations.   All  of  the  in-plant  controls
presented  in  section  IX  will  have to be implemented, and additional
controls instituted as follows:

    1.   Isolate and treat all process waste waters.  No process
         wastes should be discharged without treatment.

    2.   Institute maximum water reuse at all plants over and
         above the current levels of practice.

    3.   Provide improved solids recovery at individual waste
         sources.
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RATIONALE  FOE  THE  SELECTION  OF   THE   BEST   AVAILABLE   TECHNOLOGY
ECONOMICALLY ACHIEVABLE

Corn_Wet_Milling

Cost_gf_A2Elicatign-

As presented in Section VIII, the investment cost for providing the test
available  technology  economically  achievable  for  a  treatment plant
serving a hypothetical medium-sized corn wet mill is  $2,832,000.   This
cost  is  exclusive of any expenditures for in-plant controls.  Detailed
information  en  operating,  maintenance,  power,  and  other  costs  is
contained in Section VIII.

AgeJL_Sizex_and_Ty-p_e_of_Productign^Facilities-

As  discussed  in  Section  IX, differences in age or size of production
facilities in the wet corn milling subcategory  will  not  significantly
affect  the  application  of  the best available technology economically
achievable.  Likewise, the production methods employed by the  different
mills  are similar and will not influence the applicability of this same
technology.

Engineerin3_AS£ects_of_A2£lication-

The control technologies specified herein have  not  been  fully  demon-
strated  in  any  segment  of  the  grain  milling  industry.  The tasic
treatment processes, however,  namely  activated  sludge  and  deep  bed
filtration,  have  been used in industrial and municipal applications in
recent years to provide a high quality effluent.  One corn  wet  milling
company  is  currently  installing  such a system.  This treatment plant
should demonstrate the applicability of  this  level  of  technology  to
grain milling wastes.

In  developing  the  effluent limitation guidelines attainable using the
best available technology economically achievable, it was concluded that
end-of-process treatment could effect an additional EOD5_  and  suspended
solids  removal  of 50 to 70 percent, compared to the levels achieved by
the best practicable control technology currently available.   Deep  bed
filtration  will remove most of the remaining suspended solids following
secondary clarification.  In so doing, experience has shown that over 50
percent of the remaining BOD is normally associated with these suspended
solids and is therefore removed.

For the dilute waste  waters  from  plants  using  once-through  contact
cooling  water, effluent concentrations of 10 mg/1 of BOD5_ and suspended
solids should be achieved.  For those plants using recirculated  cooling
water, effluent concentrations of from 30 to 50 mg/1 can be accomplished
by application of this level of treatment.

It  is recognized that the soluble BOD5 level in seme of the plants that
generate concentrated waste streams may not permit  attainment  of  BOD5
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levels  represented by the values in Table 16, using only end-of-prccess
treatment.  It is expected that the in-plant control measures that  have
been  recorrmended  will  reduce  the net raw waste loads sufficiently to
permit attaining the effluent limitations as proposed.  Each of the  in-
plant  control measures is practiced by one or more plants, although not
necessarily at the same plant.  Thus, the in-plant control technology is
available, although its application may be restricted in certain mills.

In summary, the combined effect of the application of the best available
technology economically achievable and application  of  all  practicable
in-plant  control  measures should permit the corn wet mills to meet the
effluent levels presented in Table 16.


Process^Changes-

No basic process changes will be necessary to  implement  these  control
technologies.   In fact, many of the in-plant modifications have already
teen made by some corn wet mills.

Non-Wat er_2u§ lit y__Environment al_ As p_ects-

The application of the best available technology economically achievable
will not create any new sources of air or  land  pollution,  or  require
significantly  more  energy than the best practicable control technology
currently available.  Power needs for this level of treatment technology
were estimated to be about 225 kw  (625 hp) for the model plant developed
in Section VIII.  This demand  is  small  when  compared  to  the  total
production plant power requirements.

Corn_Dry^Milling

The  cost cf applying the best available technology economically achiev-
able, defined above to a moderately large mill, has  been  estimated  in
Section  VIII to be $323,000.  Data on operating, maintenance, and power
costs are presented in Section VIII.

The application of this control technology is  not  dependent  upon  the
size  or  age of mill.  As discussed under corn wet mills, the treatment
technology has not been demonstrated in the grain milling industry,  but
is   transferable   from  other  waste  treatment  applications.   Power
requirements for the prescribed treatment system are small  compared  to
the overall production demands.  Other environmental considerations will
not be affected by the application of this control technology.

Vyheat,, Milling  (Bulgur^

The  best available technology economically achievable can be applied to
a medium-sized bulgur mill for an  investment  cost  of  about  $93,000.
Other cost information is contained in Section VIII.

Plant  size  and age and other production factors will not influence the
applicability of the suggested control technology.  Experience in  other
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waste treatment applications amply demonstrate the technical feasibility
of  the  control  system.   Energy,  air  pollution,  noise,  and  other
environmental  considerations  have  been  evaluated  and  will  not  be
significantly affected by the application of this technology.

Fice_Milling	(Parboiled_Rice^

Application  of  the  specified  best  available control technology eco-
nomically achievable to a medium-sized parboiled rice plant is estimated
to cost $347,000.   Section  VIII  contains  additional  information  on
operating, maintenance, and energy costs.

Once  again,  the prescribed control technology has been demonstrated in
related waste treatment applications.  Energy needs are  small  compared
to  the  production  power demands.  Other environmental factors such as
noise and air pollution will be little affected by  the  application  of
this control technology.
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                               SECTION XI

                    NEW SOURCE PERFORMANCE STANDARDS


INTRODUCTION

Standards  of performance are presented in this section for new sources.
The term "new source" is defined to mean "any source,  the  construction
of  which is commenced after the publication of the proposed regulations
prescribing a standard of performance."  These standards of  performance
are  to reflect higher levels of pollution control that may be available
through  the  application  of  improved  production   processes   and/or
treatment techniques.

Consideration should be given to the following factors:

    a.   The type of process employed and process changes;
    b.   operating methods and in-plant controls;
    c.   batch as opposed to continuous operations;
    d.   use of alternative raw materials;
    e.   use cf dry rather than wet processes; and
    f.   recovery of pollutant as by-products.

The  new  source  performance  standards represent the best in-plant and
end-of-process control technology coupled with the  use  of  new  and/or
improved  production processes.  In the development of these performance
standards, consideration must  be  given  to  the  practicability  of  a
standard permitting "nc discharge" of pollutants.


NEW SOURCE PERFORMANCE STANDARDS

The  performance standards for new sources in the grain milling industry
are identical to  the  effluent  limitations  prescribed  as  attainable
through  the  application  of the best available technology economically
achievable as presented in Section  X.   These  new  source  performance
standards are given in Table 17.

These  values represent the rraximum average allowable loading for any 30
consecutive calendar days.  Excursions  above  these  levels  should  be
permitted  with  a maximum daily average of 3.0 times the average 30-day
values listed below.

At  the  present  time,  a  "no  discharge"  standard  is   not   deemed
practicable.   It  is  anticipated that continued advancement in end-of-
process treatment methods and in-plant control measures will  result  in
future revisions in the new source performance standards.
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Industry
                                Table 17

                   New Source Performance Standards*

                               BOD^            Suspended Solids  pH
Corn wet irilling
0.357
20
0.179
10
                                                                  6-9
                        0.0357       2.0       0.0179     1.0     6-9
                               No discharge of process waste waters
Corn dry irilling
Normal wheat flour
  milling
Eulgur wheat flour
   milling              0.0050       0.3       0.0033     0.2     6-9
Normal rice milling            No discharge of process waste waters
Parboiled rice milling  0.070        0.007     0.030      0.003   6-9

*Maximum average of daily values for any period of 30 consecutive days


RATIONALE FOR THE SELECTION OF NEW SOURCE PERFORMANCE STANDARDS

C g r n_Wet_Mi11i ng

The  specific  control  technologies  to meet the new source performance
standards are not presented in this  document.   It  has  been  a  basic
premise, however, that all of the in-plant controls discussed in Section
VII  would  be  incorporated  in  a  new mill.  In addition, the end-of-
process treatment system is to be equivalent to that suggested  for  the
best  control technology economically achievable.  Recognizing that this
level of waste water treatment has not been demonstrated  in  the  grain
milling  industry,  it  is  nonetheless felt that the combined effect of
complete in-plant controls and the new treatment  technology  will  meet
the  new scurce performance standards.  Factors considered in developing
these standards are summarized in the following paragraphs.

££°3uctign_Prccess-

The basic  production  process  used  in  corn  wet  milling  cannot  be
significantly   altered.    The  industry  has  historically  been  very
aggressive in developing and utilizing new production technology.  While
new plants will undoubtedly incorporate some new or  improved  types  of
equipment, the basic process will remain largely in its present form for
the foreseeable future.

Ogerating_Methgds^and_ln-Plant_Cgntrols-

New plants offer the possibility of instituting better operating methods
and  in-plant  controls.   Without  the physical constraints of existing
facilities, essentially  all  of  the  in-plant  controls  discussed  in
Section  VII  can  be implemented.  Instrumentation is also available to
improve plant operation and reduce accidental waste discharges.  Greatly
reduced waste loads should be attainable by  these  and  other  in-plant
improvements.
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The  control  technology  recommended  to achieve new source performance
standards is equivalent  to  that  represented  by  the  best  available
technology  economically  achievalble, namely an activated sludge system
followed by deep bed filtration.  Inasmuch as this type of treatment has
not been specifically  applied  to  corn  wet  milling  wastes,  initial
operating  experience  with such systems may not fully meet the expected
50 to 75 percent BODj> and suspended solids removals form  the  secondary
clarifier  effluent.   The application of complete in-plant controls and
the use of good operating methods in  new  plants  should  significantly
reduce  the  raw  waste  loads  from these facilities.  Accordingly, the
effluent reductions specified by the  proposed  new  source  performance
standards  should  be  achievable  for all new plants.  As experience is
gained with the end-of-process treatment, particularly  the  removal  of
suspended  materials by filtration, it may be possible to reduce the new
scurce performance standards, as given in  Table  17.   At  the  present
time,  however,  these standards represent the best engineering judgment
of those levels that would be achievable for new sources.

Changes^ in^Unit Qperations-
As stated above, the basic corn wet milling process is likely to  remain
unchanged  for  the  immediate  future.   Minor  modifications  in  unit
operations are continually being made in this industry subcategory,  but
no  additional  improvements that would have a major impact on the waste
water discharges have been developed.

Ev-Prpduct_gecoyerY-

Ey-product  recovery  has  long  been  practiced  in  corn  wet   mills.
Application  of the best in-plant controls will undoubtedly increase by-
product recovery, but will probably offer no new recovery avenues.

Corn Dry Milling

The new scurce standards for corn dry mills are based on the application
of the best available technology economically achievable as  represented
by  a  high  level  of  end" of -process treatment.  Corn washing, the one
source of process waste waters, is considered to be  essential  by  many
mills.   Although  some  mills  only  dry  clean  the  corn,  many ether
companies believe that washing is necessary to  control  microbiological
contamination  and  product  quality.  Depending on raw material quality
and technical food product considerations, it is expected that most  new
mills will require corn washing.

Barring  a  total  changeover  to  dry  cleaning  methods, little can be
accomplished in reducing total plant waste loads.  In-plant controls and
operating methods may reduce  total  flows,  but  will  not  appreciably
affect the total quantities of contaminants.
                                105

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      Mi 1 1 i ng__(Bu Igur )

The  effluent  levels  to  be  achieved under the new source performance
standards for bulgur production also reflect the application of the best
available end-of-process technology as  described  in  Section  X.   The
basic  production  process  requires  water for soaking (or cooking)  and
this  single  source  of  process  waste  water  cannot  be  eliminated.
Operating  methods,  in-plant controls, and by-product recovery will not
influence process waste loads except perhaps in  terms  of  quantity  of
waste  water.   Some  by-product  recovery,  i.e., the use of biological
treatment solids in animal feeds, may result from the application of the
prescribed treatment technology.
Process waste waters in parboiled rice  production  originate  from  the
steeping  operation.   This  unit  operation  is  integral  to the basic
parboiling process and cannot be eliminated  or  changed  significantly.
Likewise,  in-plant  controls and operating methods can reduce the total
waste water flow in some instances, but not the total amount  of  pollu-
tants.   The new source standards of performance, therefore, provide for
the application of the best available technology economically achievablp
as described in Section X.   Recovery  of  biological  sclids  from  the
treatment system for use in animal feed is envisioned.
                                 106

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                              SECTION XII

                            ACKNOWLEDGMENTS
The   Environmental   Protection   Agency  whishes  to  acknowledge  the
contributions to this project by Sverdrup G Parcel and Associates, Inc.,
St. Louis, Missouri.  The work at Sverdrup & Parcel was performed  under
the  direction of Dr. H.G. Schwartz, Jr., Project Manager , and assisted
by Jesse Nachowiak and Bavid Schenck.

 Appreciation is extended to  the  many  people  in  the  grain  milling
industry  who  cooperated  in  providing  information  for  this  study.
Special  mention  is  given   to  company   representatives   who   were
particularly helpful in this effort:

Mr. William Graham of the American Maize-Products Company;
Mr. Arthur DeGrand of the Anheuser-Busch, Inc. Company;
Mr. W. B. Holmes of Burrus Mills Division, Cargill, Inc.;
Mr. Leonard Lewis and Mr. Howard Anderson of the Clinton Corn
Processing Company;
Mr. E. J. Samuelson and Mr. William Von Minden of Comet Rice
Company;
Mr. D. R. Erown, Mr. R. C. Brandquist, Mr. F. W. Velguth, and
Mr. G. R. C. Williams of CPC International Inc;
Mr. Donald Thimsen of General Mills;
Mr. E. M. Eubanks, Mr. R. Koll, and Mr. G. C. Holltorf of the
Grain Processing Corporation;
Mr. H. Kurrelmeier of Illinois Cereal Mills, Inc.;
Mr. D. Smith of Lauhoff Grain Company;
Mr. V. Gray of P£S Rice Mills, Inc.;
Mr. Tom Mole of Quaker Oats Company;
Mr. William Hagenbach, Mr. Robert Popma, Mr. Joe Wasilewski, and
Mr. John F. Hcman of the A. E. Staley Manufacturing Company;
and Mr. W. J. Staton and Mr. W. H. Ferguson of Uncle Ben's Rice Company.

Acknowledgement  is  also  given to the following trade associations who
were helpful in soliciting the cooperation of  their  member  companies:
American  Corn  Millers  Federation, Corn Refiners Assoc., Inc.; Millers
National Federation; National Soft Wheat Millers Assoc.; Protein  Cereal
Products Institute; and the Rice Millers Assoc.

Appreciation  is  expressed  to  those  in  the Environmental Protection
Agency who assisted in the performance  of  this  project:  John  Riley,
George  Webster,  Pearl  Smith,  Acquanetta McNeal, Frances Hansborough,
Patricia Dugan, Max Cochrane, Linda Huff, Arlein Wicks, Reinhold Thieme,
Taylor Miller, Kenneth Dostel and Gilbert Jackson.
                                107

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                              SECTION XIII

                               REFERENCES


1.   Sensing, H. O. and Brown, D. R., "Process Design for Treatment.
         of Corn Wet Milling Wastes," P£Oceedings_Third_Nat ional
         SYm£Osium_of_Food_Prccessin2_Wastes, New Orleans, Louisiana,
         March 28-30, 1972.

2.   Sensing, H. O. ,  Brown, D. R. , and Watson, S. A., "Waste Utili-
         zation and  Pollution Control in Wet Milling," American
         ^SSOciati.on_of_Cereal_Chernists, Dallas, Texas, October
         13, 1971.

3.   "CRA 1973 Corn Annual," Corn_Ref iners_Assgciationx_Inc^x
         Washington, D. C.f 1973.

H.   Church, B. D. , Erickson, E. E. , and Widmer, C. M. , "Fungal
         Digestion of Food Processing Wastes," Food_TechnologYr
         36, February, 1973.

5.   Church, B. D. , Erickson, E. E. , and Widmer, C. M., "Fungal
         Digestion cf Food Processing Wastes at a Pilot Level,"
         Seventy^ second National Meeting, American_institute_of
         Chemicjal^Engineers^ St. Louis, Missouri, May 21-24,  1972.
6 •   Q2D§2li^ted_Fe ed_Tra de_Manua l_and_Gr a in_Mi ]. 1 i ng__Ca t al og ,
         National Provisioner, Inc., Chicago, Illinois, 1964.

7-   Crog_ProductignA_]:972_Annual_SurnmarY» Crop Reporting Board,
         Statistical Reporting Service, U.S. Department of
         Agriculture, Washington, D. C. , January 15, 1973.

8-   Current_Industr i al_Repor t s , Flour Milling Products, Bureau
         of the Census, U.S. Department of commerce, February,
         1973.

9 .   Fl our _M i 1 ling_Pr o due t s_- _Cur r ent_Indus tr i a l_Regort s , U.S.
         Department of Commerce, Bureau of the Census, Industry
         Division, Washington, D. C. , February, 1973.

10.  Gehrig, Eugene J. , "Mounting Tide of 'Bulgur1 Pacific Wheat
         Specialty Rolls Out from Seattle Mill," Anieri.can_Mil_ler
                        December, 1962.
11.  Inglett, G. E. ,  Corn_^ __ CultureJL_Processi.ngx_Products, AVI
         Publishing  Company, Inc., Westport, Connecticut, 1970.

12,  Matz, Samuel A., Cereal_Technolggy, AVI Publishing Company,
         Inc., Westport, Connecticut, 1970.

13.  "New Wheat Processing Plant in Hutchinson Set for Export
                              109

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         Trade," Amer_ican_Mi^ ler _and_Proc e s sor , January, 1963.

         C ensus_of _Manuf actur er sx_Gr ain_Mi ll_Pr oduc t s , U.S.
         Department of Commerce, Bureau of the Census, August,
         1970.

15.  Parolak, G.  M. , "Field Evaluation of Aerated Lagoon Pre-
         Treatment of Corn Processing Wastes,"  Mi_Si_Thes i s ,
         Purdue University, December, 1972.

16.  Patent_J2x8^Ux327A_Method_of_Processin3_Wheat, D. H. Robbiris,
         Fisher Flouring MillsT"

17.  Polikoff, A. and Comey, D. D. , "American Maize-Products
         Company - Preliminary Report", Businessmen_f or _ the
                iHt§£§Si » Chicago, Illinois, May, 1972.
18 .  PAiPOductsandChemica]. sPilot
         liant_Studiesx Stanley Consultants, June 19, 1972.

19. "Report on Industrial Water and Waste Program, Phase I -
         Water and Waste Inventory for Grain Processing Corpora-
         tion, Muscatine, Iowa," Stanley Consultants, 1968.

20. Seyfried, C. F. , "Purification of Starch Industry Waste Water,"
         Proceedings of the__ 2 3rd_IndustrialWaste_Cgnference,
         Purdue University, Lafayette, Indiana, May 7-9, 1968.

21. Smith Robert, Cost_of_Conventional_and_Advanced_Treatment_of
         Wa^st §_Wat er s , Federal Water Pollution Control Administration,
         U.S. Department of the Interior, 1968.

22. Smith, Robert and McMichael, Walter F. , Cgst_and_Performance
         Federal Water Pollution Control Administration, U.s
         Department of the Interior, 1969.

23. "United States Statistical Summaries," The^Northwestern
         MjJ.ler, Volume 278, No. 9, Minneapolis, MinnesotaV
         September, 1971.

24. West, A. W., "Report on April 19, 1972 Investigation of the
         Wet Corn Milling Waste Treatment Plant, CPC International,
         Inc., Pekin, Illinois," Enyirpnmental Protect ion_ Agency,
         Cincinnati, Ohio, May, 1972.

25. Willenbrink, R. V., "Waste Control and Treatment by a Corn and
         Soybean Processor," Proceedings_of_the_222d_Industrial
         ^§_§t e_Conf er ence , Purdue University, 517, 1967.
26. Witte, George C. , Jr., "Rice Milling in the United States,"
         Bulletin - AssQgiat ion of Operative Millers , 3147-3159,
         February, 1970.
                               110

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27.  World_Rice_Cro2_Continues_Decline, U.S. Department of Agri-
         culture,Foreign Agriculture""circular FRI-73, Washington,
         B. C.,  February, 1973. •
                             111

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                              SECTION XIV

                                GLOSSARY

     1 •  £ sgi. rator s

Milling machine equipment that separates loosened hulls froir
the grain.
The pericarp or outer cuticle layers and germ of the rice
grain.

     3 «  Eran^_Wheat

The several-layered covering beneath the wheat husk that
protects the kernel.

     U .  Erown_Rice

Rice from which the hull only has been removed, still retain-
ing the bran layers and most of the germ.   (Rice Millers
Association, 1967.)

     5 .  Eulgur

Wheat which has been parboiled, dried and partially debranned
for later use in either cracked or whole grain form.  (Wheat
Flour Institute, 1965.)

     6 •  Coyn Starch

Substance obtained from corn endosperm and remaining after
the removal of the gluten.

     7 .  Ccrn Syrup

Produced by partial hydrolysis of the corn starch slurry
through the aid of cooking, acidification and/or enzymes.

     8 •  Dextrose

Corn sweetener created by completely hydrolyzing the corn starch
slurry through the aid of cooking, acidifying and enzyme action.
The starchy part of the grain kernel.

    10.  Germ

The young embryo common to grain kernels (e.g., corn, wheat).
                              113

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    11.  Gluten

High protein substance found in the endosperm of corn and
wheat grain.

    12.  Hulls

The outer covering of the corn and rice kernel.  The rice
hull is normally called the lemma.

    13 .  Midd lings

Fractured wheat kernels resulting from the milling operations.

    14.  Modified_Starch

A form of corn starch whose characteristics are developed by
chemically treating raw starch slurry under controlled conditions,

    1 5 .  Farboiled_Rice

Fice which has been treated prior to milling by a technical
process that gelantinizes the starches in the grain. ,  (Rice
Millers Association, 1967) .

    16.  Fear_l§r;§  (Whitener, Huller)

Pice milling machine equipment employed to remove the coarse
outer layer of bran from the germ.

    1 7 .
The aleurone or inner cuticle layers of the rice kernel, con-
taining only such amounts of the outer layers and of the
starchy kernel as are unavoidable in the milling operation.

    18.  Steepwater

The water in which wet-miller corn is soaked before preparation.
                             114

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CONVERSION TABLE
Multiply (English Units)         by_

     ENGLISH UNIT            CONVERSION


cubic feet                   0.028

degree Fahrenheit            0.555(5

feet                         0.30U8

gallon                       3.785

gallon                       0.003785

gallon/minute                0.0631

horsepower                   0.7^57

million gallons/day          3,785

pounds                       0.^5^

pounds/hundred weight (cwt)  10.0

standard bushel, corn        25-^
  (56 Ibs) (SBu)

standard bushel, wheat       27.2
  (60 Ibs) (SBu)
                      To Obtain (Metric Units)

                           METRIC UNIT


                      cubic meters

                      degree Centigrade

                      meters

                      liters

                      cubic meter

                      liters/second

                      kilowatts

                      cubic meters/day

                      kilograms

                      kilograms/metric ton

                      kilograms


                      kilograms
    115

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>:-.-.t'-»?tii.n Agency

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cia   60606.

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