IN-PLANT MODIFICATIONS TO REDUCE POLLUTION
*************
AND
PRETREATMENT OF MEAT PACKING WASTEWATERS
FOR
DISCHARGE TO MUNICIPAL SYSTEMS
PREPARED
FOR
ENVIRONMENTAL PROTECTION AGENCY
TECHNOLOGY TRANSFER PROGRAM
DESIGN SEMINAR
FOR
UPGRADING
MEAT PACKING FACILITIES
TO REDUCE POLLUTION
CHICAGO, ILLINOIS
JUNE 12 and 13, 1973
A. J. STEFFEN
CONSULTING ENVIRONMENTAL ENGINEER
2863 ASHLAND ST.
WEST LAFAYETTE, INDIANA 47906
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024160
TABLE OF CONTENTS
Page
PREFACE ....................................... . ................ 1
I. INTRODUCTION
A. GENERAL BACKGROUND ...................................... 3
B. REGULATORY CONSIDERATIONS
1. Federal .......................................... U
2. State ................................... . ........ 8
3. Municipal ........................................ 9
a. Limitations on Concentrations of
Wastewater Ingredients ..................... 10
b. Surcharges ................................. 11
II. IN-PLANT MODIFICATIONS to REDUCE POLLUTION
A. PRACTICES in WASTE CONSERVATION
in the MEAT PACKING INDUSTRY ............................ 12
B. SEGREGATION of WASTE STREAMS ............................ 15
C . PLANT WASTE CONSERVATION SURVEY ......................... 16
D. RECOVERY of SOLIDS and BY-PRODUCTS ...................... 19
E. WATER and PRODUCT CONSERVATION .......................... 23;
F. SELECTION and/or MODIFICATION of
PROCESS EQUIPMENT for WASTE CONSERVATION ................ 2k
G . WATER and WASTE CONSERVATION in CLEANUP OPERATIONS ....... 27
III. ERETREATMENT of MEAT PACKING WASTEWATER
for DISCHARGE to MUNICIPAL SYSTEMS
A. INTRODUCTION ............................................ 29
B. FLOW EQUALIZATION ....................................... 30
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C. SCREENING and CENTRIFUGING
1. Introduction 31
2. Static Screens (Prepared by M.E. Ginaven
Vice Pres., Products & Processes
The Bauer Bros. Co., Springfield, Ohio)i. 33
3. Vibrating Screens: Dam M. Lindenmeyer
Tech. Spec., Vibrating Screens
link Belt Material Handling Div.
FMC Corp., Chicago, HI 38
ii. Other Solids Removal Systems
a. Other screening devices It3
b. Centrifuges 1;6
D. SEPARATION of GREASE
and SUSPENDED SOLIDS by GRAVITY and FLOTATION
1. General Comments U8
2. Gravity Grease Separation and
Suspended Solids Recovery in Rectangular Basins 51
3. Dissolved Air Flotation: Charles B. Grimes
Sales Engineer
Water Quality Control Div.
Envirex Inc.
A Rexnord Company
(formerly Rex Chalnbelt)
Waukesha, Wisconsin 61;
U. Other Systems 83
IV. CASE HISTORIES in WASTE CONSERVATION and PRETREATMENT 85
V. SUMMARY 88
VI. APPENDIX
A. REFERENCES 92
B. BIBLIOGRAPHY , 92
C. LIST of TRADE NAMES of EQUIPMENT MANUFACTURERS 93
ADDRESSES of EQUIPMENT MANUFACTURERS 95
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PREFACE
This manual is intended to serve as an information medium for one
section of the Environmental Protection Agency Technology Transfer Design
Seminar for Upgrading Meat Packing Facilities to Reduce Pollution. No
attempt was made to include meat processing at separate locations apart
from killing plants (dog food manufacturing, sausage plants, etc.), although
much of this information can be applied to them.
This section of the seminar relates to ""In-Plant Modifications to Reduce
Pollution and the Pretreatment of Meat Packing Wastewaters for Discharge to
Municipal Systems.11' Another technical section covers complete treatment for
discharge to a watercourse and also includes a manual. These manuals are
particularly oriented toward plant owners, managers, superintendents and
their engineering and operating staffs.
Wherever possible, copies of visual aids used during the presentations
are reproduced in the manual. The selection of speakers and writers was
based upon their familiarity with the technology being presented. Selection
of a speaker affiliated with a manufacturer of a specific product, as well as
any proprietary material presented herein, does not directly or indirectly
imply an endorsement of such product. Other manufacturers of similar products
and processes are listed in the Appendix. Cited references and a Bibliography
will also be found in the Appendix.
The material in this section will be presented to half of the attendees
on each of two separate half-days, concurrently with the other section mention-
ed above. To provide useful information within these time restrictions, the
seminar discussion must necessarily be limited to an overview of the subject
matter, but the manual covers each subject in greater depth.
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To avoid duplication, biological treatment methods are covered only in
the section of this seminar on "Treatment for Discharge to a Watercourse11',
though it is recognized that many pretreatraent systems include biological
systems to condition meat packing wastewaters for discharge to municipal
systems under municipal regulations.
Discussion of the disposal of solids, such as recovered hog hair, screen-
ings, paunch manure, and floatables and settled solids from grease basins is
beyond the scope of this manual, but prevention of discharge of some types of
solids and removal of other materials from the waste streams are included.
Subjects discussed in this manual may be studied in greater depth by
referring to the Bibliography and the technical literature of manufacturers
listed in the Appendix.
ACKNOWLEDGEMENTS
The cooperation of the contributors in the
preparation of their portions of this material and
their direct participation in the program is grate-
fully acknowledged. Thanks are also due to the many
other engineers and managers who freely contributed
many items of data, costs and operating experiences.
•
A. J. Steffen
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I. INTRODUCTION
A. GENERAL BACKGROUND.
The Importance of in-plant modification to reduce pollution (Sect* II,
of this manual) needs no emphasis here. It is a simple economic fact that
conservation and in-plant waste saving, along with water recycle and reuse
must be considered before any plant undertakes to build pretreatment facil-
ities for discharge to a public sewer, pays a municipal charge for waste-
water treatment or builds a complete treatment plant for discharge to a
watercourse.
The importance of Section III of this manual, "The Pretreatraent of
Meat Packing Wastewaters for Discharge to Municipal Systems" becomes evident
when we note that a 196? survey showed that 70$ of the wastewater from the
meat packing industry was discharged to municipal facilities.'^-' Although
we have no recent data, it seems likely that this percentage may now be
slightly lower with the continuing trend towards decentralization into
small plants discharging into independent lagoon systems in semi-rural
areas.
Wherever possible, this manual deals with waste conservation in exist**
ing plants* However, it will be evident to the reader that many of the
methods discussed are applicable largely to new plants and could not readi-
ly be retrofitted into existing plants because of space limitations and
layout. Thus each manager and engineer can make use of this manual as a
guide and "check list", evaluating each waste conservation concept as it
applies to his particular plant.
The portion on pretreatment (Section III) discusses the elements of
equipment that make up a pretreatment plant, whether it be an expansion
of existing pretreatment facilities or an entirely new system.
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The meat plant owner, operator or engineer does not need a preliminary
discussion of the processes in the industry nor does he need a separate set
of recommendations for beef kill and hog kill. Accordingly, in the interests
of brevity, the assumption is made that the reader is conversant with industry
practices. The accompanying flow chart is, however, included for reference.
B. REGULATORY CONSIDERATIONS.
1. Federal• The following discussion is limited to Federal regulations
relating to the subject matter of this manual and thus does
not include a discussion of permits for discharge to -watercourses.
a. Federal Grants Program. Public Law 92-f>00, amending the Federal
Pollution Control Act, was passed by
Congress on October 18, 1972, and contains several points of direct interest
to industry. In providing grants for new or expanded municipal treatment plants
(now amounting to 1$% of the construction cost), The Federal government requires
that the municipality "has made provision for the payment.... by the industrial
user, of the treatment works, of that portion of the cost.... allocable to the
treatment of such industrial wastes.." for which he is responsible.
(Section 20U (b) (1).
The Law also provides that,,by April 16, l?73j the EPA shall "issue guide-
lines applicable to payment of waste treatment cost by industrial and non-
industrial recipients of waste treatment services which shall establish (A)
classes of users of such services, including categories of industrial users;
(B1) criteria against which to determine the adequacy of charges imposed on
classes and categories of users reflecting factors that influence the cost of
waste treatment, including strength, volume, and delivery flow rate character-
istics (surges and maximum flows) of wastes; and (C) Model systems and rates of
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We
Solid
iste
Liquid
Primary
Proc
:esses
Secondary
Products
r
r
Animals
\L
Livestock
Pens
x ___ __
I
I
I Solid Waste
I Composting '
|_Land_RII_ |
Killing
Blood Processing
y
Eviscerating
Trimming
Cooling
H
r
. Cutting.
Deboning
Viscera Handling
Inedible
Rendering
Processing
Grinding
Curing
Pickling
Smoking
Cooking
Canning
Edible
Rendering
i
si>
Secondary '
' Treatment
Grease trap
or
Flotation
Unit
Flowchart for Packinghouse
»Dried Blood
Hide Removal
Hog Dehairing
Hide Processing
Hair"ecovery
•v
Hides
Hog Hair
Liver
Heart
Kidneys
•Tripe
-^Carcasses
By-Products
>Cut Meat
Lard
Edible tallow
Products
-> Process Flow
•> Waste Flow
(From North Star Research & Development Inst., "Final Report, Industrial
Waste Study of the Meat Products Industry'*, EPA Contract No, 68-01-0031).
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user charges typical of various treatment works serving municipal—industrial
communities.11 Thus the EPA will be involved in the rate structure or formula
developed for sewage charges for all municipalities (including sanitary dis-
tricts) where grant funds are allocated, in order to assure repayment of the
government's cost in proportion to the cost of the treatment works attributable
to the industry's wastewater discharged to the municipal sewer. The accompany-
ing exhibit ^Quantity or quality formulas based on total cost or average unit
costs11 is excerpted from "Federal Guidelines — Equitable Recovery of Industrial
Waste Treatment Costs in Municipal Systems" (Oct., 1971)* Since this guideline
was published prior to the date of enactment of the Act, it serves only as an
indication of possible procedures* No guidelines pursuant to the Act have been
developed at this writing.
Pretreatment prior to discharge to "publicly owned" (i.e., municipality,
sanitary district, county, etc.) treatment works is also regulated under the
Act. Sect. 307 (b)(l) requires that the EPA, by April 16, 1973, "publish pro-
posed regulations establishing pretreatment standards for introduction of pol-
lutants into treatment works...., which are publicly owned, for those pollutants
which are determined not to be susceptible to treatment by such treatment works
or which would interfere with the operation of such treatment works. Mot later
than 90 days after auch publication, and after opportunity for public hearing,
the Administrator shall promulgate such pretreatment standards."' The Act
allows a maximum of three years for compliance by industry and also provides
for revision of these standards as new technology warrants.
The limits may be anticipated to be in two general categoriesi one, pro-
hibited items (such as ashes, hair, whole blood, paunch manure, and similar
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Quantity or quality formulas based on total cost or average unit costs
This method of cost allocation or derivation of industrial charge
is computed by several forms of the generalized formula:
Note: The principle applies equally well with additional
terms (e.g., chlorine feed rates) or less terms
(e.g., v0V± only).
Where C.^ = charge to industrial users, $/yr.
vo = average unit cost of transport and treatment
chargeable to volume, $/gal.
bo = average unit cost of treatment, chargeable to
BOD, f/lb.
SQ = average unit cost of treatment (including sludge
treatment) chargeable to SS3 $/lb.
V-L = volume of waste water from industrial users, gal./yr.
BJ_ = weight of BOD from industrial users, Ib./yr.
Sj_ = weight of SS from industrial users, Ib./yr.
The terms bQ and so above may include charges (surcharges) for
concentrated wastes above an established minimum based on normal
load criteria.
Inasmuch as it is an objective of the Guidelines to encourage the
initiation and use of user charges, this general method of allocation
is both preferable and acceptable,
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materials untreatable in municipal plants), and the second category, maximum
concentrations of such items as BCD, suspended solids and other constituents
which, in excess, could interfere nith the operation of the municipal plant.
Many municipalities will use such maxima in their structure of charges, figur-
ing a volume cost per 1000 gallons per month (perhaps on a sliding scale
similar to water billing or, more conveniently, a definite multiplier of the
municipal water bill). To this volume cost, surcharges are added for BOD, sus-
pended solids, grease, and possibly other pollutions! Ingredients at a determined
rate in cents per pound of each such pollutional ingredient beyond a certain
basic concentration, the base being representative of the concentration of domes-
tic sewage (also see item 3> following item 2 below).
2.. State. This discussion will be limited to the state's role in in-plant
conservation and pretreatment prior to discharge to public
sewers. Recycling and reuse of water and any other major in-plant changes should
be reviewed with the state meat inspection agency if the plant is under state,
rather than federal inspection.
Approval of plans for pretreatment of wastewaters prior to discharge to
public sewers may be a requirement under the state regulations for approval of
plans for sewage treatment. States differ on this point.
In some states, the plant may also be required to have a state-licensed
wastewater treatment plant operator for such pretreatment facilities.
Municipal ordinances relating to wastewater are generally reviewed by the
state stream pollution control authority. Thus ordinances and regulations
regarding industrial wastewater and charges and surcharges will most likely be
reviewed by the state before passage.
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If the city has not passed the legislation required by the EPA for a
Federal Grant for sewage treatment construction, the state (which allocates
these funds) may advise EPA to withhold a portion of the grant until all
requirements are met.
flhen. a new plant is planned for connection to a public sewer and such
connection will substantially increase the floir or pollutional characteristics
of wastewaters reaching the municipal wastewater treatment plant, the agency
owning the sewer is required by federal law to advise the state of such change*
3. Municipal. Municipal ordinances and regulations that are less
stringent than those set up under the Federal Act
discussed under 1 above, will be required to alter them to conform, but if
they exceed the federal standards, they need not be reduced, unless the city
elects to do so*
Existing municipal ordinances and regulations covering discharge to the
public sewers vary widely. A large number of cities use, as a guide, the so*
called Model Ordinance published as part of Manual of Practice No. 3 of the
Water Pollution Control Federation. Article 7 of the Model Ordinance contains
an extensive list of limiting characteristics applicable to meat packing waste-
waters discharged to public sewers* The background material, along with
Article V, are too voluminous to reproduce in this manual. The "Regulation of
Sewer Use" (Manual of Practice No. 3) is available at $1*50 ($1.00 to Federa-
tion members) from) Water Pollution Control Federation, 3900 Wisconsin Ave.,
Wash,, D. C. 20016. A. !£>£ quantity discount is available in lots of twelve
or more copies.
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Municipal ordinances generally cover the subject under two headings:
Limitations and Surcharges.
a. Limitations.
1) Prohibition of objectionable matter. Various minerals, toxic
materials and waste characteristics and materials that are
difficult to treat are excluded. The following examples are
typical:
d.) The Metropolitan Sanitary District of Greater Chicago includes
the following exclusions on ingredients that may affect packing
plant effluents:
Noxious or malodorous liquids, gases or substances yrhich either
singly or by interaction with other wastes are sufficient to
create a public nuisance or hazard to life or are sufficient to
prevent entry into the sewers for their maintenance and repair,
Solid or viscous wastes which cause obstruction to the flow in
sewers or other interference with the proper operation of the
sewerage system or sewage treatment works, such as grease, un-
comminuted garbage, animal guts or tissues, paunch manure, bone,
hair, hides and fleshings.
Waters or waste containing substances which are not amenable to
treatment or reduction by the sewage treatment process employed
or are amenable to treatment only to such degree that the sewage
treatment plant effluent cannot meet the requirements of other
agencies having Jurisdiction over discharge to the receiving
waters.
Excessive discoloration.
k») Other cities use similar limiting clauses in their ordinances,
often copied from the Manual of Practice No. 3> from which the
above wording was adapted in part*
2:) Concentration of pollutional characteristics.
&) The Ordinance of the Metropolitan Sanitary District of Greater
Chicago provides no top limits for BOD or suspended solids but
does include "surcharges" for these items (see 2 a, following).
It does, however, limit temperature to a maximum of 1J>0° F. (6£° C)
and fats, oils or greases (hexane solubles) to a maximum of 100 mg/1
These limits are included in many municipal ordinances.
b) Otherccities nay limit BOD to possibly 300 mg/1 and suspended
solids to 350 mg/1, more or less. "Catch-all"1 clauses are ]-;"
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also common, such as "The Term Board of Trustees is authorized
to prohibit the dumping of wastes into the Town's sewage system
which, in its discretion, are deemed harmful to the operation of
the sewage works of said Town."
tt. Surcharges.
1) The Metropolitan Sanitary District of Greater Chicago charges 2.1
cents per 1000 gallons, l.U cents per pound of BOD and 2.1* cents per
pound of suspended solids, after deducting the first 10,000 gallons
per day (and the BOD and suspended solids it would contain). Also
deducted are the sewer district tax (a property type tax) plus h mills
per day per employee, an allowance for sanitary sewage discharged dur-
ing the working day.
2.) Most of the simpler sewage billing systems are based on the water
usage, ranging from about 50£ to as high as 1.2$% of the water billing,
with maxima for BOD, suspended solids, grease and sometimes other in-
gredients. These are basic sewer charges applicable to all users,
domestic, commercial and industrial and are not classified as surcharges
unless they include escalation for BOD, suspended solids, grease, etc.
and possibly flows, in excess of a "domestic" base. Thus the surcharge
portion of the ordinance might be similar in structure to the Chicago
ordinance, but with a charge for flow in excess of a base, and a charge
per pound of ingredients above a base represented by discharge from a
single residence.
3) Also note the guidelines under lU^Federal (above).
In general, the new Federal Act may radically modify existing municipal
ordinances and regulations*
It should also be noted that recycle and reuse of "used water" must
be checked by the USDA and any other agency having jurisdiction over
product sanitation.
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II. IN-PLANT MODIFICATIONS to REDUCE POLLUTION by A. J. Steffen
and W. H. ifi.ed.aner*
A. PRACTICES in WASTE CONSERVATION in the MEAT PACKING INDUSTRY.
Except for very small slaughtering plants, most plants recover blood,
screenable solids and grease by various in-plant systems and devices. Many
small packers without blood drying facilities or inedible rendering depart-
ments recover such materials for local tank truck pick-up operated by
specialized by-products plants in the area.
The quantity of water used varies widely, based on waste conservation
practices, blood and solids handling methods and the amount of processing
done in the plant. It may range from about 0.5 to 2.0 gallons per pound of
live weight killed.
The degree of wastewater conservation, recycle and reuse, and solids
and blood recovery in each individual plant depends upon many factors: the
age of the plantj the views of management on the subject; whether markets or
final disposal facilities for recovered blood, solids and grease are readily
available; market prices of the recoverable materials; the local regulations
regarding effluent quality and surcharge costs for plants discharging to
public sewers; and the first cost, and operating costs of independent treat-
ment if the packer discharges to a watercourse.
The low market price for recovered inedible grease in some localities
has forced many packers to dispose of it as feed-grade grease. If the meat
packing plant is conveniently located near a soap plant, the possibilities
of an improved price will provide special incentives for grease recovery.
*W. H. Miedaner, Chief Environmental Engineer, Globe Engineering Co.,
175 W. Jackson Blvd., Chicago, 111., (Consultants Serving the Food Industry).
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Variations in economics in disposing of the solids and concentrates such as
paunch manure, blood, hair, casing slimes and concentrated stick (in wet
rendering) inevitably affect the diligence -with which these pollutional solids
are kept out of the sewer.
However, the limitations and surcharge regulations for wastes discharged
to city sewers, or the cost of complete treatment if the plant discharges to
a watercourse must be carefully evaluated to establish the level of waste
conservation appropriate to the packing plant. For example, a plant discharg-
ing to its own anaerobic-aerobic pond system may find that some floatable
inert solids such as stock-pen bedding can improve the insulating scum blanket
on the anaerobic lagoon. Then, neglect in recovery of such materials would
not be important. On the other hand, a packing plant in Springfield, Mo.,
faced with a municipal waste treatment charge of $1,UOO a month, modified its
production processes (including solids recovery), so that the monthly payment
dropped to $225.
In processing and in quality control, the meat industry finds water an
essential tool to help cleanse the product and to convey and remove unwanted
materials. But in wastewater handling, water becomes a problem — a diluter
that flushes and dissolves organic matter and carries it to the sewer.
Wastewater treatment is basically nothing more than a processing system to
again separate the organic and inorganic matter from the water that picked
it up.
The goal of every wastewater engineer is to remove organic solids "dry"
without discharging to the sewer, and then use an absolute minimum of water
for the essentials of sanitation. The closer we come to this goal, the simpler
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11*
becomes the irastewater problem. This goal provides the pattern in waste
conservation in the plant, and can be briefly summarized in the folloY/ing
axioms:
1. Use water wisely — only enough to get the job done.
2. Keep waste solids in bulk whenever possible, for disposal as a
solid or as a concentrated sludge, without discharging to the
sewer.
3. Clean with high pressure and minimum water volume (small hoses).
Use the right detergents in the right proportions to clean well
with minimum rinsing.
it. Recycle water as much as possible, within the limits of USDA
regulations. Some reconditioning, such as cooling or screening,
may be necessary for recycling in some instances.
5. Use the minimum pressure and volume for washing product, consistent
with quality control. High pressure in washing product may drive
soil into the product and also wash away valuable edible protein
and fat.
6, Control volume, temperature and pressure automatically. Dependence
upon manual regulation can lead to waste.
?• Use valves that shut off automatically when the water is not needed.
For example, photo-electric cells are used in Japan to turn water on
when product is in a washing position.
8. Study each process independently. General rules alone will not do
the job.
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B. SEGREGATION of WASTE STREA.1E .
In meat packing, it has been common practice to provide separate
sewer systems for grease wastes; non-grease (variously termed
"manure" sewer or "red"' sewer); clear waters from chilling, condensing and
cooling operations} surface and roof water (surface drainage); stock-pen
wastes and sanitary wastes. However, for new plants, further segregation
is often desirable in order to permit removal of pollutional ingredients
before the wastewaters mingle with other plant waters. Screening equipment
can be smaller and can be designed for the special solids present. In some
cases, such segregated waters may be sufficiently dilute to use for recycling.
In the interests of dry or semi-dry manure separation, a separate manure
sewer should be provided in new plants for all sources of manure. This waste
can be pretreated by screening, followed by dissolved air flotation. The
floated solids can be analyzed for fats and wet rendered if warranted.
The grease sewer should receive only those wastes that contain grease.
If the color of the rendered tallow is a factor, special diligence must be
exercised that all manure-bearing wastes be kept out of the sewer. The
settled solids should be discharged over a screen, dried and utilized in feeds,
if possible. They contain an appreciable amount of grease. Basically, the
grease sewer should receive wastes from boning, cutting, edible and inedible
rendering, casing washing (after manure and slime have been removed), canning,
sausage manufacturing, slicing, prepackaging, smoking and smoked meats hanging,
cooking, tank car loading and washing, carcass coolers, lard and grease storage
areas, equipment washrooms, pickling areas and the like.
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The conventional non-grease seirer receives wastes from hog scalding,
de-hairing, tripe washing, chitterling washing, and kill drains up to and
including the polisher. It also receives the flow from manure recovery
systems when a separate manure screen is not provided.
Hide processing waters are commonly recirculated either with or without
screening for solids reduction. If these waters must be dumped, they should
be screened separately and then discharged to the non-grease sewer.
Vapors from cooking and rendering operations can be cooled and condensed
through heat exchangers and recycled to dryers, or sent to the grease sewer*
All clear water (jacket cooling water, air conditioner water, steam
condensate and chill water) should be carefully separated for reuse.
Curing pickle (undiluted) has a very high BOD and should be reused when-
ever possible. Run-off pickle from processing should be caught in recycling
pan systems as part of the injection equipment. In a recent study, it was
found that only 2$% of the pickle produced was retained in the product, the
rest was lost by general leakage and spilled from the injection machines.
The BOD of pickle varies but the dextrose alone has a BOD of about 660,000 mg/1,
Sanitary wastes are, of course, discharged directly to the city sewer or
to a separate treatment system, and should not enter any pretreatment elements.
C. PLANT WASTE CONSERVATION SURVEY.
The first step in waste conservation is a well-organized and
well-executed waste conservation survey, backed by management.
The following elements would be part of the basic survey described by Ournham
& Associates in the Manual, "Basics of Pollution!", distributed and discussed
earlier at this seminar.
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First the engineer should collect data on the volume, nature and general
facilities of the business. If he is a company employee, he already has this
information. In addition, he should know all plans for future construction.
He should attempt to develop a 10-year forecast of business. If the wastewaters
discharge to a city sever, he should know something about population trends in
the area and the possibilities of industrial growth and whether such growth
will add load to the municipal plant. Whether the wastewaters discharge to a
public sewer system or to the packer's private treatment plant, he should be
familiar with the system and the sewage treatment plant and the requirements
for the receiving stream.
The approach to wastewater control need not be complicated or expensive.
The principal effort applied should be in the direction of preventing product
(and contaminants) from entering the waste stream and to reduce water use to
a minimum. High waste load areas should be probed first. Accurate sampling,
chemical analysis and flow measurements need not be performed initially, but
can be deferred until after the gross problems have been solved.
Since most suspended solids in meat wastewaters are organic, their
removal results in a reduction of BOD. Suspended solids concentrations (after
screening) are a rough measure of BOD and can be easily and quickly measured.
Dissolved solids can be measured with a conductivity meter. Red color
indicates the presence of blood, a very large contributor of BOD. A simple
jar test will give some information. During the initial phase of in-plant
waste control, approximate figures are sufficient. Flows must be measured
at the time of sampling. Flows can be estimated or simply catch the flow in
a pail or 50 gal. drum for a period of time. The gallons per minute can be
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calculated. In some instances it may be necessary to break into a sewer line
or disconnect a pipe to obtain a sample or flow measurement,
Solids per unit volume, with associated water consumption will give a
measure of the pounds of organic wastes generated. Problem areas can then
be studied for methods of control. In many cases, & small outlay of money
will effect substantial waste control. Records should be kept to follow
progress.
The following waste load ranges are listed to provide a rough guide line.
They cover a broad range because they include small and large operations \ some
small plants with no inedible rendering and no blood recovery, and others with
a broad line of meat processing, with inedible rendering and blood recovery.
TYPICAL PLANT WASTE GENERATED
PER
1000 Ibs LWK (Live Weight Kill — an species)
BOD k to 18 Ibs per 1000 Ibs LWK
SUSPENDED SOLIDS 3 to 1? Ibs per 1000 Ibs LWK
GREASE 1.5 to 12 Ibs per 1000 Ibs LWK
FLOW 600 to 2000 gals, of water per 1000 Ibs LWK
The following equation can be used to convert laboratory analyses and
flow to pounds per 1000 Ibs LWK.
Pounds of pollutant per 1000 Ibs LWK = Flow in
1000 Ibs LWK x 1,000,000
where mg/1 = milligrams per liter (from laboratory data).
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Anyone interested in typical flow, BOD, suspended solids and grease
from various processing operations will find useful data in Reference No.3
(see Appendix), These values vary widely from plant to plant; thus in this
manual, it will be most useful to cite methods of correction without attach-
ing specific values to each process or process change. The order of prior-
ities for in-plant waste conservation will vary depending upon the results
of the waste conservation survey in each individual plant.
D. RECOVERY of SOLIDS and BY-PRODUCTS.
1. Blood has the highest BOD of any liquid material emanating from
meat processing. It has an ultimate BOD (approximately
20-day) of 1*05,000 mg/l.(2) Customary analytical methods for 5-day BOD
are not sufficiently accurate in these high ranges, but are estimated to
average from 150,000 to 200,000 mg/1. Considering that one head of cattle
contains approximately k9 Ibs. of blood, the 5-day BOD of blood from a single
animal is about 10 Ibs., as against about 0.2 Ibs. 5-day BOD discharged per
person per day.
Thus, if the blood from a single animal killed in a day is discharged
to the sewer, its pollutional load would be equivalent to that of 50 people.
Clotted blood (about 70$ of the total) has a BOD (ultimate) of about
U70,000 mg/1 while the liquid portion is about 200,000 mg/l.'2) Comparing
these figures with the ultimate BOD of domestic sewage of about 300 mg/1,
it is evident that blood conservation pays.
The curbed bleeding area that discharges to the blood tank should be
as long as possible and the blood should be squeegeed to the blood tank before
the valves are switched to drain to the sewer for the cleanup operation.
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The floor and walls should then be cleaned with a minimum of water by use
of small diameter hoses. If the water used in the first rinse is held down
to 30 to f>0 gallons, it can be discharged to the blood tank as an added
conservation measure. The additional cost of evaporating this quantity of
water will, in most cases, be far less than the cost of treating it as
wastewater.
Water is sometimes mixed with blood to facilitate transportation in
pipes. The evaporation of this added water in the dryer is an added expense
and can often be eliminated if the drain from the bleeding area to the blood
tank is large enough and the blood tank is located to permit a straight drop
into it. If the blood is pumped to the tank, the piping layout should be
checked. If sewer alignment cannot be improved to prevent drains from clog-
ging, de-coagulating electrodes can be installed to prevent coagulation,
(Appendix C, 1st item). Troughs to catch and convey blood should be pitched
and curved to facilitate squeegeeing before washing.
Blood processing methods are important in waste conservation. For lowest
losses to the sewer, continuous dryers are most common, using a jacketed vessel
with rotating blades to prevent burn-on. Continuous ring dryers are also
popular. They produce a relatively small amount of bloodwater that, in small
plants, is usually discharged to the sewers. This bloodwater can be further
clarified by discharging it through a small settling tank. This is a waste
conservation problem that warrants further study. The older steam coagulation
systems are more serious problems in waste conservation, since a substantial
amount of fines can be lost when the coagulated blood is screened. A combin-
ation, of paunch manure solids and bloodwater can be cooked to produce a
hydrolyzed hair stick but the process economics should be explored before a
packer embarks on such a project.^ Casing slimes can be added to the
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blood dryer if desired or can be dried with other product in conventional
inedible dry rendering.
2. Paunch Manure is either wet or dry dumped for recovery of tripe.
Wet dumping consists of cutting the paunch open in a
water flow, discharging to a mechanical screen and thence to the manure sewer,
This washing action carries a large fraction of the BOD from the paunch waste
solids into the water phase. Paunch solids are about 1$% water, weigh about
5>0 to 60 Ibs. per animal and have a "'dry dump" first-stage BOD of over
100,000 mg/1 (five-clay BOD, slightly less). Eighty percent of this BOD is
soluble.
Dry dumping consists of dry discharge of the manure solids down a chute
to an inedible area for ultimate disposal as a waste solid or blending to
produce a marketable solid. After dry dumping, fines are removed by washing
and are discharged into the manure sewer.
Stomach and peck contents may contain undigested grains which contain
proteins and fats. An investigation may disclose that these materials can be
routed directly to a dryer, unopened, if the resulting product is acceptable
as an ingredient in the end product (also see II F 5).
3. Casing-saving operations contribute substantially to pollution.
Waste from the de-sliraer should be passed
directly to cookers in inedible rendering or dried with the blood, A small
catch basin in the immediate casing area will recover sizable amounts of good
quality fats. Water should be kept at a minimum. Sprays should be checked
for efficiency in volume of water used, proper design, proper direction and
maximum spacing.
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h» Stockpen wastes are high in nutrients and should be segregated in
a manner to allow alternate methods of disposal.
Pens should be dry cleaned and the waste should be hauled away for land
disposal.
Usually runways and pens are hosed down periodically. Consideration
should be given to segregation of this strong liquid waste for disposal by
trucking or piping for disposal directly on farm land, within the limits of
regulations regarding land disposal.
5. Scraps and Bone Dust. Plant operations in cutting and trimming
should be carefully examined for opportunities
to intercept waste solids before they enter the sewer. Scraps and liquids
from the hog-neck washer should be caught in a container directly beneath the
washer. Some form of grease trap can suffice. Collected contents should be
routed direct to rendering. Bone dust from sawing operations is an important
source of pollution and contains a high concentration of phosphorus. Bone
dust is of fine texture and when diluted with water is difficult to recover.
It should be recovered intact by catching directly in containers or sweeping
up and hauling to the inedible rendering department.
6. Hide curing operations are becoming increasingly involved as segments
of tanning operations are transferred from tanneries to
beef slaughtering plants. During winter months, a single hide can contain
60 Ibs. of attached lumps of manure, mud and ice. In addition, salt, caustic,
acids and fleshing waste enter the sewage stream. The washwater should be
recycled, or retained for separate treatment (usually screening) if consider-
able volumes are involved.
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7. Disposal of tankwater. If lard is wet rendered or if any inedible
wet rendering is in service at the plant,
the disposal of tankwater may be a problem (BOD about 22,000 mg/1). In
processing lard by low or medium temperature continuous rendering, one process
uses about 1J>0 Ibs. of water (as steam) per 230 Ibs. wet rendered product.
However, there is a market in some areas for 50 to 60% edible stickwater pro-
duced by evaporating this tankwater. In another process, less water is used
and it goes out with the cracklings. In contrast, inedible tankwater is
evaporated and is commonly blended with animal feed as inedible stickwater.
Under no circumstances can this high BOD waste be discharged to the sewer.
In some cases the tankwater can be trucked to a central processing plant for
evaporation. It can also be dried with inedible solids.
E. WATER and PRODUCT CONSERVATION.
Water conservation is an essential part of an in-plant wastewater
control program. It has been shown that packing plants using the
most water per animal generate the most waste per animal. Excessive wash-
ing, especially with hot water, removes juices and tissues from product and
flushes them into the sewers. Water usage can be reduced at many locations.
The viscera pan sterilizer and the final carcass washer are large water
users. These washing operations should be modified so that when the carcass
chain stops, the water automatically shuts off. This can be done with
solenoid-operated valves under control of the conveyor-chain motor starter.
The viscera pan sterilizer uses large amounts of 180° water. This often
runs continuously during the work day (and during the clean-up period). .
Thought should be given to engaging the services of those skilled in spraying
techniques — not only to design the sterilizer for economy in water use,
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but also to design cleaned-in-placa (CIP) cleaning systems for the viscera
pans (see F 6 following). The sprays on the final carcass washer should be
checked for proper spacing, direction, shape of spray, pressure and water
consumption.
F. SELECTION and/or MODIFICATION of PROCESS EQUIPMENT for WASTE CONSERVATION.
1. Chitterling "washers can be improved by fitting them with limiting
orifices and spray nozzles rather than drilled
pipes. Water consumption can be reduced from 130 to 70 gpra by proper design
of sprays and control of water and pressure on these units.(3)
2. Hog-casing cleaning machines can be modified to recover the slime
from the stripper, which amounts to
0.2 Ibs. of dry solids per hog.'-''
3. Scalding tub: A means of slow drainage of the scalding tub and
separate removal of the sludge will reduce the waste
concentration materially. It is reported that 100 hogs, at maximum slaughter
rate, produce 11.2 Ibs. of BOD and 23»5> Ibs. of suspended solids.0) it may
be expected that as much as 30# of the BOD and 80# of the suspended solids
will settle in the tub. The scalding tub can be fitted with a perforated
riser pipe in the drain, extending about 6" above the floor of the tub. The
residual sludge can then be squeegeed through a 12'" x 12" square sluice gate
at tank floor level and discharged to a truck for disposal as waste solids.
U. Low or medium temperature continuous edible rendering can be
i
accomplished with a limited amount of
water discharged to the sewers. This factor should enter the cost analysis
when a new system is purchased, (see D 7 above).
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5. Hasher-washer screen. It is not uncommon to eliminate the hasher-
isasher screen. The entire product can be
dry rendered if the quality of the rendered product is not a sensitive
consideration. The added bulk in dry rendering is small when balanced
against increased yield and the elimination of the hasher-washer screen
drainage (see preceding D 2)«
6. Automated (CIP) Cleaning. For daily cleaning, consideration should
be given to automated cleaning of viscera
pans, tank trucks, continuous rendering systems, conveyor tables, piping,
cookers and dryers. Systems that will conserve water and labor are available
from detergent manufacturers.
7» Heart washers. A considerable amount of raw water is used to chill
hearts in modern heart washers. A study of this
operation may prove that the use of refrigerated chill water will conserve
water and result in a better t'shelf life" product,
8. Offal areas. .In the offal areas, continuous streams of water are
sometimes used to aid in moving product down chutes.
Special sprays or redesign of chutes will reduce water usage at these points.
Any sprays made up of a pipe with drilled orifices are usually inefficient
and should be replaced with engineered sprays, designed for minimum water
consumption, proper pressure and maximum effective coverage. Master shut-off
valves can be used to shut groups of sprays during rest periods. Ball type
valves are effective for this service.
9. Knife and sterilizing boxes are often operated with excessive amounts
of water and temperature. The use of electric
temperature-controlled knife boxes should be considered — particularly in
coolers where steam causes condensation problems and refrigeration losses.
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10. Sanitary facilities for Personnel. Press-to-open valves (foot or
knee-operated) should be used on all lavatories.
Drinking fountains should not run continuously. Refrigerated water
fountains will conserve water.
11. Animal drinking water should be minimal but consistent with satis-
factory yields. In the past, it was believed
that abundant drinking water was necessary for good yieldsj consequently,
drinking troughs flowed continuously. Recent information indicates that
animals can go one or two days without water and show negligible yield reduction.
Time clock control of the master valve for drinking water supply, programmed
for one minute on and four minutes off will reduce water use by 80$.
12, Once-through raw water in refrigeration condensers and compressor
cooling jacket water is expensive. Such water should be either
reused in plant processes or recycled through
a heat exchanging device — cooling towers or evaporative condensers.
Evaporative condensers are usually the most feasible.
If possible, blowdown water should be returned to the soil because of
its high mineral content. Generally, regulated quantities can be discharged
to the city sewer directly without violating limiting regulations. Boiler
blowdown water is "soft water" and can be reused in cleanup operations or in
fabric wash machines. This requires some experimentation to develop a proper
blend of plant water supply with the blowdown water, particularly relating to
temperature •
13 • Manual washing of meat and offal products can be improved. Washing
operations requiring "under-the-spray" time of less
than 5o£, should have press-to-open sprays, On-site observations have dis-
closed many hand-washing operations (particularly offal) with time under the
spray of not more than 1(#, Sprays should not flow unattended at work tables.
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In addition to press-to-open spray valves, efficient re-design of spray heads
will improve product cleaning and conserve iiater. Pressures and volume of
flow should be controlled with pipe restrictions or locked valves to establish
a minimum consistent with quality results. Photo electric cells could serve
well as automatic control (see II A 7).
lit. In dry rendering systems, many plants mix raw cold water with cooking
vapors from rendering dryers to condense vapors and
reduce odors. The mixture of vapors and water is discharged to the sewer.
A recent study of a typical operation disclosed that each dryer used 120
to 130 gpm of water and the mixture contained 118 mg/1 of BOD and 27 ng/1 of
grease. The BOD and grease were likely due to carryover from overloaded
dryers. The water consumption represented hO% of the entire plant water. A
heat exchanger was recommended for direct water condensing to eliminate the
cooling water loss. Heat extracted from the vapors can be removed by means
of a cooling tower or returned to the plant hot water system. Commonly,
cooking operations closely follow killing operationsj thus the recovered
heat can be reused.
In some instances a portion of dissolved air flotation cell effluent is
routed to the inedible cooker vapor condensers. For details on dissolved
air flotation, see III C, 2 and 3.
Condensed cooking vapors from dry rendering operations should be routed
to the fat-bearing stream if they\contain a significant amount of recoverable
solids.
G. WATER and WASTE CONSERVATION in CLEANUP OPERATIONS.
Old-fashioned cleanup operations usually use excessive amounts of water -
hot and cold. Many cleanup hoses discharge 10 to 20 gpm of high velocity
to 180° hot water. Some operators believe that a flood of hot water for
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cleaning floors and equipment is necessary* Indiscriminate use of hot water
is not only undesirable from a wastewater control standpoint, but erodes floors,
walls, removes lubrication from equipment, and can cause electrical failures.
It is altogether too common for cleanup men to remove floor drain grates
and flush meat scraps down the drain, believing that a screen or catch basin
will trap all solids. By the time the scraps are recovered, they have been
broken up in the flow and much of the organic matter has been dissolved or
suspended in the wastewater to the extent that it cannot be removed without
complete treatment — by the packer or by the city. Tlhat started as a remov-
able scrap has then become a part of a wastewater treatment load*
Floors and equipment should be "dry cleaned" before hosing and scraps
taken to the inedible rendering. This first step in cleanup requires rigid
surveillance.
Smaller nozzles on smaller hoses and application of modern cleaning methods
will reduce water. For example, a kink-type valve, that is inserted in the
hose and opens only when the hose is bent, will automatically stop the water
when the operator drops the hose. Water should be automatically controlled
to maintain the lowest temperature, lowest volume and highest pressure
consistent with each cleaning job. Effective detergents to emulsify fats and
lift proteins and soil will reduce the quantity of rinse water required. Well-
qualified cleaning consultants are available for guidance.
The use of automated "cleaned-in-place" (CIP) systems will reduce and
control water use. (see II F 6 preceding).
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III. PRETREATMENT of MEAT PACKING 1ASTEWATERS for DISCHARGE to MUNICIPAL SYSTBE
A. INTRODUCTION.
1. Advantages of Pretreatment: Although compliance -with municipal
regulations regarding the quality of a
meat packer's wastewater for discharge to the city's sewer will usually
determine the degree of pretreatment, there are some factors that may
encourage pretreatment beyond the levels required by ordinance:
a. A higher quality of pretreatment may be economically Justified
if the city's charges and surcharges are at a level where some addition-
al pretreatment becomes economically advantageous.
b. The meat packer may prefer to assume treatment responsibilities
to avoid complaints from the municipality.
c. There may be indications that the future will bring increases in
the city's rate structure.
d. Grease and solids may have a good market in the area. Proximity
of a soap plant or similar grease market may produce economic advantages
for grease recovery or may warrant some expense in improving quality of
the finished inedible grease or tallow. Such improvements will also im-
prove the wastewater effluent,
2.. There are some Disadvantages t
a. The pretreatment will be placed on the property tax rolls unless
state regulations permit tax-free waste treatment for industry.
b. The maintenance, operation and record-keeping may be expensive
or burdensome.
c* The burden of good operation increases as the treatment becomes
more complex and extensive.
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3. Evaluating Needs. After the plant has been completely surveyed and
all possible waste conservation and water reuse
systems have been catalogued, the necessary pretreatment system must be
designed and the cost estimated. Those parts of the treatment attribut-
able to flow (such as grease basins and dissolved air flotation) should
be totaled and reduced to a cost per 1000 gallons. Similar "break-outs"
in costs per pound can be carried out for grease, suspended solids and BOD,
Then each major in-plant expense for waate conservation, water re-
cycle and reuse can be evaluated based on the estimated reduction in flow,
BOD, suspended solids and grease. From such data, priorities can be
established for each in-plant waste conservation measure suggested in the
survey.
The future planning for the meat packing plant should serve as a
guide to determine piping arrangements and suitable locations (and sizes)
for projected facilities.
lu Costs. Waste-sacving and treatment costs should be charged back to
the department from which the flow, BOD, suspended solids
and grease emanated. Selected costs of some of the equipment common to
pretreatment will be discussed later.
B. FLOW. EQUALIZATION.
Equalization facilities consist of a holding tank and pumping equipment
designed to reduce the fluctuations of waste
streams. They can be economically advantageous whether the industry is
treating its own wastes or discharging into a city sewer after some pre-
treatment. The equalizing tank will store wastewater either to recycle
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or rouse the wastewater or to feed the flow uniformly to treatment
facilities throughout the 2U-hour day. The tank is characterized by a
•varying flow into the tank and a constant flow out. Lagoons nay serve
as equalizing tanks or the tank may be a simple steel or concrete tank,
often without a cover.
Advantages of equalization for the meat packer discharging to a
city sewer are:
a. In-plant pretreatment can be smaller, since it can be designed
for the 2J*-hour average, rather than the peak flows.
b. The city may have penalties for high peaks which can be avoided
by equalization.
Disadvantages are few;
a. More equipment to maintain and operate.
b. Additional fixed costs.
C. SCREENING and CJENTKIFUQIHQ.
1. Introduction. Since so much of the pollutions! matter in meat wastes
is originally a solid (meat particles and fat), or
sludge (manure solids), interception of the waste material by various
types of screens and centrifuges is a natural step*
Unfortunately, when these pollutions! materials enter the sewage
flow and are subjected to turbulence, pumping, and mechanical screening,
they break down and release soluble BOD to the flow, along with colloidal
and suspended and grease solids. Waste treatment — that is, the removal
of soluble, colloidal and suspended organic matter is expensive. It is
far simpler and less expensive to keep the solids out of the sewer entirely.
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But, because in-plant conservation is, at best, imperfect and people
are fallible, final organic solids separation in the main effluent sewer
is generally employed. Various combinations of facilities for pretreat-
ment may be selected, including screening, gravity grease and solids
separation, dissolved air flotation and biological treatment of various
types (this last item is covered in the manual on "Treatment of Meat
Packing Wastewaters for Discharge to a Intercourse").
The information in this discussion of screening and centrifuging can
be applied both for in-plant waste conservation and waste treatment.
The diagram in Section III C 3 shows where screens might be used
throughout the plant. Whereas vibrating screens are shown, other types
of screens could bo suitable for service in the locations cited. When-
ever feasible, pilot scale studies are warranted before selecting a
screen, unless specific operating data is available for the specific use
intended, in the same solids concentration range and under the same
operating conditions.
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III.C 2 STATIC SCREENS
Prepared by M. E. Ginaven, V.P. Products and Processes
The Bauer Bros. Co.
Subsidiary of Combustion Engineering, Inc.
Springfield, Ohio
During the past several years, a substantial number of so-called static screens
have been installed in many process industries to recover suspended matter from
plant effluents or liquid flows within a plant. Highly successful screening
operations have been achieved in the meat packing, tanning, canning, textile,
and paper and board products industries, as well as in domestic sewage treatment
operations. Interesting new developments are underway, such as the treatment
of wastes from animal producing farms and poultry processing plants.
In most instances, the installed equipment represents new functions or concepts
in recovery and generally involves recycling or some other use of the recovered
solids. In many cases, stationary screens are installed as replacements for
screens that require moving parts to make a suitable separation of solids from
a process stream.
1. Basic Design Concepts;
The primary function of a static screen is to remove "free" or transporting
fluids. This can be accomplished by several ways and, in most older con-
cepts, only gravity drainage is involved. A concavely curved screen design
using high velocity pressure-feeding was developed and patented in the 1950's
for mineral classification and has been adapted to other uses in the process
industries. This design employs bar interference to the slurry which knives
off thin layers of the flow over the curved surface.
Beginning in 1969, U.S.A. and foreign patents were allowed on a 3-slope
static screen made of specially coined curved wires. This concept used
the Coanda or wall attachment phenomena to withdraw the fluid from the
under layer of a slurry which is stratified by controlled velocity over
the screen. This method of operation has been found to be highly effective
in handling slurries containing fatty or sticky fibrous suspended matter.
Since the field tests to be reported were conducted on the later design of
stationary screen, details of this unit were herein presented. The device
is known commercially as a Hydrasieve. A typical installation of a single
screen operating on industrial waste water is illustrated in Figure 1.
2. Method of Operation;
The slurry to be screened or thickened is pumped or may flow by gravity into
the headbox of the machine. As shown in Figure 2, the incoming fluid over-
flows the weir above the screen area and is accelerated in velocity and
thinned in depth as it approaches the screen. A lightweight hinged baffle
is incorporated into the assembly in such a position that it reduces tur-
bulence in the flow. This is accomplished by the shape of the foil which
causes the fluid to respond to Bernoulli's theorem through the wedge-shaped
entrance. The increasing velocity of fluid draws the baffle toward the
surface of the screen.
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FIGURE 1
Solids
Gravity feed
of liquids/solids I
Self cleaning,
non clogging stainless
steel screen for
continuous dewatering
Removed or
recovered
solids
Headbox
Alternate
feed inlet
FIGURE 4
FIGURE 2
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Suspended solids tend to stratify in the thin stream, and fibrous materials
align themselves lengthwise with the direction of flow. Figure 3 shows a
segmental section of the screen wires and the slurry as it contacts the
upper end of the Hydrasieve screen. Note that the wall attachment of the
fluid to the metal bars or wires draws or bends an under portion of the
flow through the openings. Part of the underflow also moves along the
arcuate surfaces of the wires and is primarily concentrated at the apex
of the downward curve. Here it falls by gravity from the screen back
or flows in streams attached to the underside of the wire assembly in
a central path between the supports. The screen pattern permits a
maximum of fluid extraction based on the limit of flow rate and screen
area. Figure 4 illustrates the screen design which is registered under
the trademark Mar-Vel1.
On the first (top) slope of the screen most of the fluid is extracted from
the bottom of the stream travelling at 25° from the vertical. When the
angle of the screen changes to 35° some additional fluid is withdrawn,
and usually the massing solids begin to roll on the surface, due to the
residual kinetic energy. This action compacts the solids very slightly,
On the final slope of the screen, the solids tend to hesitate for simple
drainage action, but are always moved off the flat surface by displace-
ment with oncoming material. The effluent is aerated as it passes through
the screen in ultra thin ribbons completely exposed to a natural or con-
trolled atmosphere.
3. Unique Features;
The arrangement of transverse wires with unique singular curves in the
sense of flow provides a relatively non-clogging surface for dewatering
or screening. The screens are precisely made in No. 316 stainless steel
and are extremely rugged. Harder, wear resisting stainless alloys may
also be used for special purposes.
Openings of 0.010 to 0.060 inches meet normal screening needs. The essential
features of the Hydrasieve are covered in U.S. Letters Patents No. 3,452,876
and No. 3,751,555. Other U.S. patents are pending. Patents are also issued
and pending in foreign countries.
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Meat Processing Industry Installations;
A broad range of usage for Hydrasieve screens has been developed for meat
processors and related operations, including the feed lots and stockyards
as well as the tanning and hide processing industries. In these fields
of service the Hydrasieve may be modified to provide a "waterfall" (patent
applied for) feed concept which can more effectively cope with high loadings
of fat or grease in the slurry being screened. This development resulted
from research work done on commercial equipment by the Institute of Leather
Technology, Milwaukee, Wisconsin, and it has been widely utilized by the
processors of animal hides.
Paunch Manure
Paunch manure, or the residue from cattle stomachs, consists of fluids plus
straw>corn and minor miscellaneous solids. The Hydrasieve screen is an
excellent device for screening this slurry, and usually a ,040" opening
screen is used. The solids are readily separated from the carrying stream
and a 72 inch Hydrasieve will normally handle a flow of 600 GPM. Solids
are usually above 5 per cent.
Hog Stomach Contents
This material is essentially whole and split corn with some hair and the
possibility of fat. Usually, a .040" opening screen is employed and flow
rates of about 500 GPM are obtained on a 72 inch wide unit.
Hog Hair Recovery
In hog processing, the animals are scalded and dehaired in a beater-scraper
type of machine. Material coming from this operation is hair and scurf,
a dandruff-type flake. Also present in this operation is foam which is
self-generating because of the gelatin which is cooked out of the skins.
Ash from Smoke-Hakers
In smoking sausage and other meat products, sawdust is burned to produce
smoke. The ash is washed from the smoke-makers and should be removed
before going in grease recovery systems, as this is an unwanted product
in the rendering. Hydrasieve screens offer a satisfactory means of
screening the wash water.
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Hog Hair Recovery
Seventy-two inch (72") units with .020" openings are presently in use on this
application. Flow is UOO-500 GPM with loads to 1,000 GPM when the scalding
tub is dumped. Some problems existed in the operation due to foaming, but
are solved with proper cold water sprays over the screen and/or anti-foam
at 10-20 GPM concentration ahead of the screen.
Hair screening is improved with the stockyard, paunch r.anure, or stomach
contents added to the flow.
Total Waste Flow
The normal total waste flow from a packing plant is quite heavy with respect
to flow, solids and fat. Normally, when a packer screens his total flow it
is a safety measure used as primary settling, ahead of additional treatment,
such as pressurized air floatation. The material from the screen may be
rendered.
Presently, a 72 inch unit with ,010" screen operates on total waste flow of
500-700 GPM. Sprays are being used and the application is quite successful.
A typical operation on a waste stream from an operation where cattle, hogs
and sheep were processed is indicated by the following test data:
No. 552-2 72"x5H" Hydrasieve with .010 Marvel Screen
Flow Rate - 550 GPM
Solids Removed - 10,000 lb,/day (dry)
Solids Passed - 6,076 Ib./day (dry)
(80 minus 30 mesh) Effluent Solids - 920 PPM
Solids Removal - 62.5%
Solids Removal from Stick Water
Stick water is product water and condensation water evolved in the process of
wet or steam rendering of lard and tallow. Normally, stick water is evaporated
to produce a high protein feed additive. Solids in stick water are coarse and
fibrous in inedible rendering, and soft and stringy in edible renderings.
Normally, stick water is hot (130-160°) as it goes over the screen, elimi-
nating grease blinding.
Expeller Grease Solids Removal
After meat scraps are rendered in melters, grease is drained from the solids.
The solids are then pressed in screw-presses and the additional grease is
expelled. This grease contains solids which are normally settled out before
the grease is filtered. This grease was sent over a .020" test screen and
solids were removed to the extent that settling could be eliminated. Flow
is low, but separation is also slow. About 5-10 GPM could be sent over a
18" - .020" screen with adequate results. Modifications need to be made
so the flow would start at the overflow weir, rather than in a headbox.
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Hide Processors
Green (untreated) hides are delivered from the meat packer and are either
processed immediately or cured in brine. The first process is to wash the
hide in a drum washer where manure and dirt is removed. Some hair and manure
balls are also removed and sent to the sewer. The Hydrasieve is used here
to permit recycling of the wash water and for preliminary solids removal.
A 72 inch unit with a .060" screen permitted processor to reduce his flow
from this operation by at least half. Seventy-two inch (72") units are
handling 700 GPM effectively.
A fleshing machine is then used to remove tissue particles and tails.
Handling this flow, due to its high fat content (5-14%), may be done
with a Hydrasieve with the waterfall adapter and periodic cleaning.
To cure the hides, they are saturated in brine solution. The brine is con-
tinuously regenerated through a "lixator. Brine should be screened on a
Hydrasieve to insure proper operation by removing the hair and manure which
does accumulate in the brine race-way, or merry-go-round. A .030" screen
in a 72 inch unit will handle 450 GPM of this solution.
Summary;
Almost every static screen application problem has its own, slightly different,
design parameters to be met, and the need for some in-plant evaluations is
sometimes required. However, usually experience can be relied upon for an
adequate background to engineer a new installation. As a guide, the follow-
ing brief specifications are suitable for preliminary planning of an in-
stallation of effluent screen.
TYPICAL DESIGN INFORMATION FOR STOCKYARD EFFLUENT
BASED ON USE OF .040 INCH SLOT OPENING
HYDRASIEVE
No. 552-18"
No. 552-36"
No. 552-48"
No. 552-60"
No. 552-72"
No. 552-72-2
No. 552-72-4
No. 552-72-6
No. 552-72-8
No. 552-72-10
OVERALL
WIDTH
2
3.5
4.5
5.5
6.5
7
14
21
28
35
DIMENSIONS
DEPTH
3.5
4
5
5
5
9.5
9.5
9.5
9.5
9.5
- FEET
HEIGHT
5
5
7
7
7
7.3
7.3
7.3
7.3
7.3
WEIGHT
POUNDS
350
550
650
800
1000
1800
3600
5400
7200
9000
CAPACITY
G.P.M.
75
150
300
400
500
1000
2000
3000
4000
5000
PRICE FOR
ESTIMATING
$ 2,600
$ 3,200
$ 4,000
$ 5,000
$ 6,000
$10,000
$20,000
$30,000
$40,000
$50,000
-------
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SCteEEN SIZE
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EST. WEISHT
C.50UBS.
95OLBS
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No. 552 HYDRAiSIEVE
THE VAUCM MO*. CO
D55Z 115
W».S DE.X-OO30Z
-------
38
C 3« Vibrating Screens - D. 14. Lindenmeyer, Tech. Specialist, Vibrating Screens
Link Belt Material Handling Equipment Division
FMC Corp., Chicago, 111.
Vibrating screens have many uses in a meat packing plant. The
accompanying flow diagram illustrates the various areas where they can
be used in waste conservation.
This portion of the seminar and manual is intended to acquaint you
with the design criteria and the basic theory of vibrating screens.
Vibrating screens are designed to:
a. Convey material retained on the screen surface. This must be
done to uncover the opening so that the cloth can pass the
undersize material or liquid.
b. Agitate the bed of material on the screen surface. Agitation
and stratification are required to open the bed so that the fine
particles or liquids can work their way down through the large
particles and pass the openings.
c. Dislodgement of particles which stick or wedge in the opening.
Particles with dimensions nearly the same size as the opening
will clog. The motion of the screen must dislodge the particles.
d. Distribute the material in order to make most efficient use of
the entire screening area. The motion of the deck should
distribute the material over the deck evenly.
e. Retention of material before discharge. For high efficiency,
sizing or removing water from the solids, it is desirable to
retain the oversize as long as possible. The material must be
moved faster at the feed end to obtain quick distribution and a
shallow bed where the volume is the greatest. At the discharge
end where the volume is least, the rate of travel should be
slowed to allow the remaining fines or liquids to be removed.
-------
Menr Process i u
-------
ko
Vibrating screens are an economical piece of equipment, varying in
siae from 2' x Ij.' to 81 x 20', made up of three major parts:
1) The vibrating frame or as some may call it the box. This is
either the welded structure or the bolted assembly that supports
the vibrating mechanism and the screening medium, mounted hori-
zontally or declined on isolation springs.
2) The screening medium, cloth, perforated plate or panels.
3) The vibrating mechanism— the heart of the vibrating screen —
imparts the motion into the vibrating frame.
The effectiveness of a vibrating screen depends on a rapid motion.
Vibrating screens operate between 900 rpm and 1800 rpmj the motion can
either be circular or straight line varying from 1/32" to 1/2" total travel.
The speed and motion are selected by the screen manufacturer for the par-
ticular application.
The vibrating screen is driven by a shaft turning in a pair of bearings.
The shaft carries unbalanced weights, either machined into or keyed to the
shaft. This assembly is normally driven by a V-belt drive.
When the unbalanced weights are rotated the screen follows the weights
through a path. When a vibrator is placed on the top of the box, a slight
rocking action will take place, resulting in elliptical motion with the
ellipse leaning toward the vibrator. This motion tends to move the material
away from the feed and retard it at the discharge end. The screen box is
mounted on springs to keep vibration from being transmitted to the supports.
On most vibrating screens the cloth is pulled tightly across longitudi-
nal steel members equipped with rubber caps. The cloth may be easily changed
by loosening the tension bolts and sliding the screen cloth out at either end.
-------
Of prime importance in the selection of a proper vibrating screen is
the application of the proper cloth. The capacities on liquid vibrating
screens are based on the percent open area of the cloth. With this in mind,
cloth should be selected with the proper combination of strength of wire
and percent of open area. If the waste solids to be handled are heavy and
abrasive, vrire of a greater thickness and diameter should be used to assure
long life. However, if the material is light or sticky in nature the
durability of the screening surface may be the smallest consideration. In
such a case, a light wire may be necessary to provide an increased percent
of open area.
Screen cloth is woven in a variety of materials, such as black steel,
spring steel, all types of stainless steel, monel and brass wire. Normally,
on liquid waste applications, a type No. 30U stainless steel wire is used.
However, when conditions require other types of metal, special wire cloths
can be supplied.
In our discussion of various installations, a term will be used
frequently to designate the opening, this term is "mesh". Where mesh is
referred to as a number, it refers to the number of openings to the linear
inch. The mesh is counted by starting from the center of one wire and
counting the number of openings to a one inch distance. If the count does
not work out to an even number, the fractional part of the opening should be
specified.
Vibrating screens are economical in first cost and in operating costs.
The NRM (illustrated) is used in liquid separation extensively and the
U1 x 8' unit costs slightly more than $3,000, with feed flume and tank in
black steel. Prices vary with feeding arrangements, surface sprays (if any),
and other details, such as special metals and coatings.
-------
liquid vibrating screens
39288B
4598?
-------
ii. Other Solids Removal Systems.
a* Other Screening Devices: Vibrating, rotary and static screens
are the most popular screens for
separating solids from meat packing plant wastewaters.
One type of barrel or rotary screen (see Figure "A"), driven by
external rollers, receives the wastewater at one open end and discharges
the solids at the other open end. The liquid passes outward through the
screen (usually stainless steel screen cloth or perforated metal), to a
receiving box and effluent sewer mounted below the screen. The screen is
usually sprayed continuously by means of a line of external spray nozzles.
The screen is usually inclined towards the solids exit end. This type is
popular as an offal screen but has not been used to any great extent in
secondary "polishing"1 — that is, in removing solids from waste streams
containing low solids concentrations. A screen of this type has been de-
veloped for recycle of hide brining waters.
Another rotary screen commonly used in the meat industry is illustrated
in Drawing B and C. This screen is driven by an external pinion gear. The
raw flow is discharged into the interior of the screen below center, and
solids are removed in a trough and screw, conveyor mounted lengthwise at
the center line of the barrel. The liquid exits outward through the screen
into a box in which the screen is partially submerged. The screen is usually
kO x UO mesh, with 1/6U"" openings. Perforated lift paddles mounted length-
wise on the inside surface of the screen assist in lifting the solids to
the conveyor trough. This type is also generally sprayed externally to
reduce blinding. Grease clogging can be reduced by coating the wire cloth
with teflon. Solids removals up to 82$ are reported.
-------
Several other types of mechanical screens have had some application
in this field. One is a rotating disc which is partially submerged in
the wasterrater flow. As it rotates, particles partially adhere and are
scalped off above the flow. The screen disc is placed vertically or at
a slight angle. Some problems arise in maintaining the seal between the
rotating disc and the flow-through box or sewer.
Another type is a circular spring-mounted horizontal screen, driven
by a motor located under the screen and equipped with variable eccentric
weights. As the motor rotates, the eccentric weights impart multiplaned
vibrations to the spring-mounted screen. These units are normally central-
ly fed at the top, with the liquid discharging through the screen to a
pan above the motor and the sludge discharging from a port at the periphery
(see sketch "D"). Pilot units (18'" dia.) are available on loan. These
screens are used in a. number of meat packing plants, principally for paunch
manure removal, for removing solids from the entire manure sewer flow and
for removing solids from the main sewer leaving the plant. Mesh sizes
range from 10 mesh for paunch manure to 80 mesh for the main plant sewer.
One plant uses three U8" diameter separators with 80 mesh screening to
handle a total main plant flow of 800 to 1100 gpm.
A horizontal rotary slowly revolving screen has been developed using
wedge bars and the Coanda effect as in the static screen described in
III C 2, page 33, but with the wastewater flowing vertically downward through
the screen. Sons of the advantages claimed for rotary design are that the
screen is cleaned in its rotation by means of a doctor blade, can be rinsed
with a stationery spray system, and that the vertical downward flow helps
backwash the screen as it flows through the screen into the receiving box
under the screen drum. Several meat packing applications are reported
but no operating data are available to date.
-------
Of *mat sawn SHOWING CONSTHUCTION »
-------
1*6
There are many other ingenious mechanical screens. Some, such as
a vertical spinning drum, have successfully screened meat waste solids.
Other screen systems have been tested and are in limited use. With the
impetus on need to improve effluents, testing such devices may be
accelerated.
b>. Centrifuges have found use in the processing of meat packing
wastewater, principally in improving the quality
and concentration of grease from grease recovery catch basins and dis-
solved air flotation.
At one plant, tallow recovery from a catch basin was enhanced by
running the skimmings through two centrifuges. At this plant, each
centrifuge is of the 3-stage type (separate streams of oil, liquid and
solids), has a capacity of 55 gpm, is driven by a 25 H.P. motor, and
cost $36,000 plus about $i|.,000 installation. The yield amounts to 80£
of the recoverable tallow, with 0.92J& moisture, and a color of 13 to 15.
The temperature is raised to 180° F. and is discharged through an 80-mesh
eccentrically weighted type 60n circular vibrating screen (see preceding
paragraph a, page 14t), then heated to 195° F. and centrifuged. The fat
is classified as inedible fancy bleachable tallow and brings top market
prices. Flow rate is about 30,000 to U0,000 gallons per day and re-
covered fats run about 5000 Ibs. per day.
One system of blood concentration, incorporates & centrifuge to
separate the water after coagulation, using a chemical aid. The
centrifuge is reported to remove about 80£ of the water. The coagulated
blood is then dried. This system, however, still produces BOD in the
effluent. Drying of whole blood is better for waste conservation.
-------
First cost and power requirements tend to limit the use of
centrifuges for waste solids recovery* However, as requirements
for effluent quality become more stringent, the centrifuge may be
used more frequently to remove residual grease and fine solids from
waste streams.
-------
D. SEPARATION of GRBASE and SUSPENDED SOLIDS by GRAVITY and FLOTATION.
1. General Comments. The "catch basin1*' for the separation of grease
and solids from meat packing waatewaters was
originally developed to recover marketable grease. Since the primary
object was grease recovery, all improvements were centered on skimming.
Many catch basins were not equipped with automatic bottom sludge removal
equipment. These basins could often be completely drained to the sewer
and were "Sludged out" weekly or at frequencies such that septic condi-
tions would not cause the sludge to rise. Rising sludge was undesirable
because it could affect the color and reduce the market value of the
grease.
In the past twenty years, with waste treatment gradually becoming
an added economic incentive, catch basin design has been improved in the
solids removal area as well. In fact, the low market value of inedible
grease and tallow has reduced concern about quality of the skimmings,
and now the concern is shifting towards overall effluent quality improve-
ment.
As might be expected, the combinations of screening, catch basins
and dissolved air flotation in pro-treatment vary widely. For example,
the Beardstown, Illinois plant of Oscar Mayer & Co., discharges the
grease sewer to a flotation tank with 30-minute detention at 30$ recycle
(no chemicals), and the manure-carrying (non-grease) sewer to a 3' x 8'
four-mesh vibrating screen followed by a gravity basin with J?0-minute
detention prior to lagoon treatment. Overall operating results show
BCD removal, 66% suspended solids removal and 16% grease removal.
-------
k9
Other pretreatment systems start with screening the individual
waste streams, followed by a gravity catch basin and then may be fol-
lowed by a dissolved air flotation unit.
Gravity grease recovery systems will remove 20 to 30£ of the BOD,
UO to 50£ of the suspended solids and 50 to 60% of the grease (hexane
solubles).
General removals for dissolved air flotation systems without
chemical treatment are about 30 to 35% in BCD, about 6C# in suspended
solids and Q0% (some as high as ?0£) in grease (hexane solubles).
Combinations of gravity catch basins (about 25 to 30 minutes detention)
followed by dissolved air flotation produce somewhat better results
because the catch basin removes the larger solids and thereby reduces
the requirements imposed upon the flotation unit. (Also see III D 3).
Chemical treatment will improve recovery when installed directly
ahead of dissolved air flotation systems. Chemical treatment can also
improve gravity separation of greases and solids, but as much as 20
minutes of flocculation may be necessary to effect significant improve-
ments.
The use of chemicals to enhance coagulation and flotation varies
widely. Generally, flotation is accomplished without chemicals, unless
effluent quality must be improved. Alum as a coagulant with or without
a polymer, is used but tends to cause an emulsion problem in the cook
tank. Ferric chloride, with or without a polymer, is also used but USDA
limitations on iron content in feeds should be checked before selecting
this coagulant, if significant amounts are to be used and if the end
product will be a feed ingredient. As knowledge of polymers improves,
-------
and their use becomes acre general, proper polymers at proper pH and
under controlled mixing conditions may be effective alone and thus
eliminate the problems incident to iron and alum treatment* Zinc
chloride has had some success as a coagulant and may be effective in
combination with a polymer* The proper pH — an important factor —
should be determined by coagulation tests.
Manure carrying sewers are commonly pretreated by means of screens,
gravity basins and sometimes dissolved air flotation prior to discharge
to the public severs. If the wastewaters are treated in a separate
system for discharge to a •watercourse, the type of biological waste
treatment may not require the degree of solids removal that may be nec-
essary for discharge to the public sewer.
Simple settling tanks are useful for stockpen flows. They general-
ly consist of shallow concrete trenches, about 3 ft. deep, designed for
cleaning with a bulldozer.(6) A simple baffle at the outlet end prevents
escape of floatables. One cattle in a feed lot will discharge 10 to 15
times as much BOD as one person in the same period of time.
-------
2, gravity Qreaae Separation and Suspended Solida Recovery in
Rectangular Basins.*
a« Design elements. Engineers are sharply divided as to the
merits of rectangular versus circular
separators for various purposes. Many engineers prefer rectangular to
circular gravity grease recovery tanks because they believe that, in the
circular tank, the grease loses its cohesiveness as the flow proceeds
outward in a radial direction, with the scum covering an ever-increasing
surface area and thereby becomes thinner as it approaches the scum removal
device at the outer periphery. Others claim that the gradually reducing
velocity of the flow as it moves radially outward improves grease separa-
tion as well as solids separation (a majority of engineers prefer circular
tanks for settling flocculent solids). However, it is safe to say that,
for gravity recovery of grease, the majority favor rectangular basins.
Accordingly, this section will concentrate on this type. In dissolved air
flotation systems (see items 3 and k of III D), the two factions are about
even. In clarification following biological treatment systems, the circu-
lar clarifiers have a decided majority.
Size criteria presented in the following are based largely on experi-
ence. If individual state standards normally applied to clarifier design
are imposed on the meat packer for catch basin design, the regulations
must, of course, be followed.
Rate of flow is the most important criterion for design of a gravity
unit. About 30 to 1*0 minutes detention time at one-hour peak flow is a
The assistance of FMC Corporation, Environmental Equipment Division,
Southern Regional Office, Atlanta, Ga., in furnishing information for
this section, is gratefully acknowledged.
-------
common sizing factor, A shallow basin, 5 to 6 ft» liquid depth is
generally preferred. This produces about one gallon per minute per square
foot area. The daily flow has little relationship to the design of grease
recovery systems.
Length to width ratio should be at least 3 to 1. Maximum widths are
about 20 ft. but heavy sludges may cause an excessive stress on the scrapers
at that width. Widths to 12 ft. are safe. Beyond this, stresses should
be checked, particularly if the system is operated intermittently.
Temperature variations can develop non-uniform density currents, re-
ducing the efficiency of grease and solids separation. Overnight icing
can occur in northern climates. Accordingly, protection against wide vari-
ations in temperature should be considered.
The design of inlet and outlet arrangements, as well as scum removal
materially affect the basin efficiency.
The bottom (invert) of the influent sewer should be above the liquid
level in the basin. The inlet, however, can enter the basin below the
liquid surface. Froperly baffled, multiple inlets will reduce inlet veloc-
ities but can cause backup in the influent sewer or in an upstream receiv-
ing box where scum can collect. Design of such a receiving box to overflow
at high flow periods could prevent scum accumulation in the box. Surface
discharge into the basin, on the other hand, can develop velocity currents
in the basin. However, multiple surface inlet openings with adjustable"
baffles will reduce entrance velocities, permit manual adjustments of
distribution of the flow across the basin width, and prevent upstream scum
accumulations.
-------
da effluent should be conducted over a weir extending the full width
of the basin. Weir overflow rates should not exceed 1000 gallons per
lineal foot per hour of maximum flow. A weir trough at the outlet will
provide double weir length if necessary.
Scum removal equipment is available in several styles:
1) The slotted "swing pipe11 scum trough (see Drawing U°l Z 292), is
popular in rectangular municipal clarifiers. In operation, it is period-
ically rotated manually to a point where the slot meets the liquid level,
allowing scum to enter the pipe and flow out one end to a receiving box.
It is generally inadequate for the quantities of scum encountered in
treating meat packing wastewaters.
2) A. powered helical scum collector (Drawing U91 I 202) is also
available which mechanizes scum pickup. Its dewatering efficiency and
its capacity do not usually satisfy the requirements for scum removal in
meat packing wastewater systems, but it is a slight improvement over the
"swing pipe"1. '
3) A more positive pick up, but using the same four-sprocket sludge
and scum scraper system, consists of a scum trough and "beach" with a
short flight type skimmer (Drawing li°l g 113)*
The skimmings trough extends the full width of the basin and should
be sloped to discharge to a receiving box where the grease can be decanted
from the residual water. In large installations, a screw conveyor in the
trough will be useful. In cold climates, the shaft of the screw can be
hollow and can be connected to a steam line to keep the scum from freezing
in the trough. The scum trough should be several inches above the liquid
-------
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-------
level. The metal "beach" provided on the upstream side for scum pickup
permits some dewatering of the scum on that part of the beach above the
water level. A short baffle fastened to the underside of the trough and
extending downward will reduce scum loss due to effluent flow moving
towards the effluent weir downstream from the trough.
li) All of the skimming arrangements described above permit some
grease to escape to the effluent because it adheres to the flights as
they pass downward under the skimming device. To eliminate this defect,
two sets of scraper flights can be provided as shown in Drawing 1*91 3 295
(sketch III). In this system, the sludge is moved independently of scum
removal, by a three-sprocket collector. A separate two-sprocket scraper
system, operating above the liquid level, moves the scum towards the scum
trough and up the beach into the trough. In this arrangement, septic
action can be prevented by operating the bottom scrapers continuously.
The scum acrapers can also be separately operated on a timer to hold the
scum and develop a cohesive dense layer, thereby reducing the liquid
content of the skimmings. Normally, about 10% of the scum picked up is
water. The two-flight system can reduce the water content about 15 to
20 percent.
A new plant utilizing this type of arrangement has a production day's
flow of 620,000 gallons per day and 860 gpm in a maximum hour. This is a
large pork plant with complete smoking and sausage manufacturing. Pre-
treatment consists of a gravity basin (equipped for adding dissolved air
flotation whenever necessary) designed for 28 minutes detention (12 ft.
wide, U5 ft. long and 6 ft. side water depth). Estimated raw waste
-------
^— t^~.J%
fu*f* flj|i«M_f STM*. *wo«t/
FiMMOMtD BY UNK BU.T-PW fnc Co*. CQUIPMIMT
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-------
concentrations are U50 mg/1 BOD, UOO mg/1 suspended solids, and 3^0 iag/1
grease. No raw waste operating data are available to date, but effluent
samples taken on Jan. 17, 1973, show BOD 2f>0 mg/1, suspended solids 70 mg/1
and grease 26 mg/1. Sanitary wastes are included in these figures.
Scraper mechanism for sludge removal may scrape the sludge to one or
several submerged hoppers, generally at the inlet end of the basin. The
need for several hoppers arises from two design limitations: first, the
side slopes for the sludge hoppers should be at least 60° with the hori-
zontal, and second, the flat bottom of the hopper should be no greater
than 2' x 2' in size.
In one innovation which eliminates the hoppers and sludge pumps, the
effluent end of the basin is built in an incline and the sludge is scraped
up the incline into a receiving trough at the top. The sludge is partial-
ly derwatered on that portion of the incline that extends above the liquid
level. The incline can be as long as necessary to accomplish the desired
i
dewatering before the sludge discharges into the trough. A screw conveyor
in the sludge trough is an added convenience to carry the sludge to a
truck or receiving box alongside the basin. The effluent weirs and scum
removal trough are, of course, upstream from the incline.
b. Basin Arrangement and Materials of Construction.
Usually two identical catch basins, with a common wall, are
desirable to permit one to operate whenever the other is
down for maintenance or repair. Note that the design example (item c,
following) is based on this arrangement.
-------
60
Concrete tanks have the inherent advantages of lower overall
maintenance and more permanence of structure. However, some owners
prefer to be able to modify their operation for future expansion or
alterations or even relocation*
All-steel tanks have the advantage of being semiportable, more
easily field-erected, and more easily modified than concrete tanks.
The all-steel tanks, however, require additional maintenance as a
result of wear in areas of abrasion.
A tank utilizing all steel walls and concrete bottom is probably
the best compromise between the all-steel tank and the all-concrete
tank. The advantages are the same as for steel, however, the all-steel
tank requires a footing underneath the supporting members, whereas, with
the steel wall tank the concrete bottom forms the floor and supporting
footings for the tank.
c. Design Example.
Given a flow, at peak hour, of 1,300 gpm, design a rectangular
catch basin.
At a selected l;0-minute detention, the volume = £2,000 gallons
» 6,950 cu. ft.
Select 6 ft. average water depth; area = 1,160 sq. ft.
Select two basins, with a common wall, each 10 ft. wide, 58 ft.
long and 6 ft* average water depth.
-------
61
d. Cost Estimates for Design Example. All costs are for two basins, with
a common wall between them. The
following cost estimates are "order of magnituden prices and should not be
used for other than rough approximations. In each particular application,
equipment prices and construction costs should be developed for the area
where the plant is located and for the specific situation.
EQUIPMENT
Basin Cost,
Concrete
n
n
Steel
«
n
Steel with
installed
$25,000
$25,000
$25,000
$29,000
$25>,000
$29,000
Concrete floor $32,000
N:
HI
$32,000
$32,000
*t5n?e
I
II
III
I
n
in
i
n
in
| Base Costt
$12,500
$23,000
$32,liOO
$12,500
$23;,000
$32,500
$12,500
$23,000
$32,500
Install. Cost
$3,000
$3,500
$5,600
$3,000
$3,500
$5,500
$3,000
$3,500
$5,500
Total
$Uo,5oo
$51,500
$63,000
$l*,5oo
$55,5oo
$67,000
$ltf,5oo
$58,500
$70,000
I • li<-sprooket collector with rota table scum pipe.
II • lie-sprocket collector with short flight skimmer without screw conveyor
in trough (slightly less with helical scum skimmer).
!
Ill • 3-sprocket sludge collector with full-length separate 2-eprocket scum
scraper system and with screw conveyor in trough.
-------
62
e. Maintenance and Operation.
1) General Comments: Most gravity grease recovery units use
no chemicals, flocculants or polymers to
achieve the grease separation. Therefore, there is no requirement for
design or maintenance of a chemical feeding system. The gravity grease
recovery unit is quite simple in construction and operation, alleviating
the need for sophisticated or highly trained operators.
In gravity grease recovery and separation, as with any system of
wastewater treatment, the overall system must be considered in addition
to the individual elements. Particular attention should be given to
maintaining low turbulence in the flow, and minimizing frequency of
pumping.
2) Housekeeping: Each gravity grease recovery system requires
a certain amount of housekeeping. After
being in operation for a few months, the equipment becomes coated with
grease. It is difficult, if not impossible, to maintain the equipment
when the parts are not visible. Hence, there is a need for scraping,
scrubbing, steam cleaning and in some cases high-pressure hosing, to
assist the people responsible for maintenance in keeping the units oper-
ational. Cleanliness also helps in the control of odors and elimination
of odor-producing bacteria.
3) Mechanical Maintenance: The day-to-day observation and
periodic checking of alignment,
grease levels in speed reducers, and greasing of bearings are natural
requirements for any wastewater equipment. Eventually the chains will
-------
63
wear and require replacement. This equipment has a wear life propor-
tional to the hours of usage, hence, operation on timers is recommended.
A high percentage of grit in the wastewater may accelerate the wearing
of the components, since the grease will tend to hold the grit into the
wearing part of the unit acting as a lapping compound and accelerating
the wear.
f• Pilot Plants* The use of pilot plants for grease recovery and
other wastewater treatment design cannot be over-
emphasized* The most important advantage to be gained from such studies
is that the pilot plant can be operated with a relative flow rate and
waste characteristics representative of that for which the ultimate plant
will be designed. One of the most frequent errors in the use of pilot
plants for design purposes is the application of pilot plant data from
one meat packing plant to another with different flow pattern, production
processes and production equipment.
Most major manufacturers have pilot plant equipment available on a
rental basis.
-------
mo
TREATMENT OF MEAT PROCESSING WASTE
BY DISSOLVED AIR FLOTATION
Charles B. Grimes
Sales Engineer - Industrial Waste Treatment Products
Water Quality Control Division
Envlrex Inc.
A Rexnord Company
Dissolved air flotation Is a waste treatment process In which
oil, grease and other suspended matter Is removed from a waste
stream. This treatment process has been In use for over fifteen
years and has been most successful In removing oil from waste
streams. Its early principal use was, and still Is, the removal
of oil from petroleum refinery waste waters. Another natural area
for application of this treatment system has been the removal of
contamlnents from the food processing plants waste streams. One
of the very first applications of this treatment system was for a
meat processing application.
Basically, dissolved air flotation is a process for removing
V
suspended matter from waste water using minute air bubbles which
upon attachment to a discrete particle reduces the effective
specific gravity of the aggregate particle to less than that of
water. Reduction of the specific gravity for the aggregate
particle causes separation from the carrying liquid in an upward
direction. As Figure No. 1 suggests, the particle to be removed
may have either a natural tendency to rise or settle. Attachment
of the air bubble to the particle Induces a vertical rate of rise
noted as
-------
FIGURE 1
-------
66
Treatment of Meat Processing Waste
by Dissolved Air Flotation
Figure No. 2 Illustrates the basic design considerations of
the flotation unit. The parameter, VT was discussed above and
the measurement of this parameter will be discussed later. Since
the waste flow must pass through a treatment unit, the particles
to be removed will have a horizontal velocity. Certain criteria
have been established for limits of the parameter VH which sets
the width and depth of the treatment unit. Therefore, as Figure
No. 2 suggests, the effective length of the treatment unit Is
directly proportional to the horizontal velocity and depth and
Inversely proportional to the vertical rate of rise of the
particle to be removed.
The mechanics of operation for a dissolved air flotation unit
are Illustrated In Figure No. 3. It can be noted that a portion
of the clarified effluent Is pressurized by a recycle pump. This
recycled flow Is pumped to a pressure tank Into which air Is
Injected. In the pressure tank at approximately 40 pslg, the
recycle flow Is almost completely saturated with air. The
pressurized recycle flow, containing the dissolved air, leaves
the air saturation tank and flows through a pressure reduction
I
valve. !
A 40 pslg pressure drop occurs at the pressure reduction
valve and causes the pressurized flow stream to relinquish its
dissolved air In the form of tiny air bubbles. This air-charged
recycle flow is then blended with the raw process flow to effect
attachment of the air bubbles to the oil and other suspended
solids to be removed. The combined flow stream (raw flow plus
-------
VT
L
-------
FIGURE 3
-------
69
Treatment of Neat Processing Waste
by Dissolved Air Flotation
recycle flow containing the air bubbles) 1s mixed and uniformly distributed
over the cross-section of the basin.
As the Incoming flow travels to the effluent end of the basin,
separation of the oil and solids from the associated liquid occurs.
Solids accumulate at the water surface and form an oily sludge
blanket. Clarified liquid flows over the effluent weir and Into
a wet well. Prom the effluent wet well, a portion of the effluent
Is reclrculated. The remainder of the effluent is removed from
the basin for subsequent treatment or discharge. The floated scum
blanket of separated solids can be removed from the basin by skimmer
flights traveling between two endless strands of chain. Since the
Influent stream may also contain small amounts of heavy solids,
such as grit, which are not amenable to flotation, provision must
also be made for solids removal from the bottom of the unit.
The preceding discussion illustrates the recycle method of
injecting the air bubbles into the waste stream. Figure No. 4 shows
all three methods of dissolved air injection currently used. Total
pressurlzatlon, as the name implies, Is where the total waste flow
is pressurized prior to entering the treatment unit. Partial
pressurlzatlon Is a method whereby a portion of the waste flow is
pressurized and mixed with the remaining raw flow prior to entering
the treatment unit.
To obtain optimum treatment with some wastes, it has been
necessary to use chemical pretreatment prior to dissolved air
flotation. The necessity for use of chemical conditioning is
normally associated with a high degree of emulslfication of the
-------
peessuee
PUMP
f. TOTAL rANK
3. PAKTIAL
4
-0
o
-------
71
Treatment of Meat Processing Waste
by Dissolved Air Flotation
oil or grease matter In waste stream flow. It Is, therefore, a
requirement to break the emulsion and form a floe to absorb the
oil or grease. It has been shown (Figure No. 5) that by Increasing
the particle size, the rate of separation Is Increased. Ploccula-
tlon as a means of promoting particle growth preceding flotation
contributes to the effectiveness of the flotation process where chem-
ical conditioning is used. The points of chemical Injection and
the possible use of flocculatlon associated with the three methods
of air Injection are shown in Figure No. 6.
The use of steel package dissolved air flotation units lends
Itself to application in the meat processing Industry. This
arrangement provides an economical, flexible design which requires
minimal construction cost and area Investment.
Most manufacturers of dissolved air flotation units have complete
line of steel tanks units to meet a wide variety of flow conditions.
Figure No. 7 shows a partial listing of steel package units manu-
factured by REX, The Model No. 9550A shown would handle a raw
waste flow of approximately BOO QPM, the Model No. 8032 handles a
raw flow of about 300 QPM, and the Model No. 6020 would handle a
raw flow of about 200 0PM. These raw flow figures indicated above
were based on a vertical particle rise rate of 0.5 FPM and recycle
rate of 33 percent.
The use of steel package units lends Itself equally well to
those applications requiring flash mixing and flocculatlon as a part
of chemical pretreatment.
-------
72
0.50
u
«2
5
IL
o
0.40
~ 0.30
0.20
0.10
FIGUK 5
EFFECT OF AVERAGE
PARTICLE., SIZE ON RATE OF RISE
1 i
lOOppm Lime-20ppm Bentonite
20% Recycle
a 40 0.50 0.60 0.70
AVERAGE PARTICLE SIZE
(mm)
0.80
-------
73
AIR
WASTE
FLOCCULATING
ACiMT
li* REQUIRED)
PW1SURE
WtTSNTlON
TANK
er FLUENT
OILYKUM
WAST*
ACCNT
AIR
*LS
FUOCCUUmON
CHAMBCft
(IF REQUIRED)
FLOTATION
CHAMBER
vl ,
CLARIFIED
EFFLUENT
> II 9 •*^N*^
fmuu
RCTtNTION
TANK
PARTIAL
OILY
WASTE
noecu-
UATION
CLOTATION
CHAMBER
(\r
-------
PRODUCT MANUAL • SANITATION EQUIPMENT
CONVEYOR and PROCESS EQUIPMENT DIVISION
CHAINBELT INC.
MILWAUKEE WISCONSIN 933OI
SECTION
(10) FLOAT-TREAT
SUBJECT Typical Arrangement-Packaged REX Float-Treat
iparator-Steel Tank with Skimmer & Sludge Removal Facilities
D»ts Sheet No.
315- 10. 501
Page 1 of 1
Issued
March 1967
Supersedes
October 1963
PLUG uuye WHCN
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REGULATNG ARE USED
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HOPPER ARRAMGCKCNT FOR TANA
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ALTZBN«T ABRANOEfcCNT WITH
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-------
75
Treatment of Meat Processing Waste
by Dissolved Air Flotation
In the following discussion, a steel package Model No. 6020
with flash mix and flocculation compartments has been used to
Illustrate the costs associated with this type of unit. The capital
cost of this unit would be approximately $37,500.00, which would
include the following equipment:
1. Flash mixer and drive
2. Flocculator and drive
3. Two-shaft surface skimmer and drive
4, Screw conveyor, sludge collector and drive
5. Complete steel tank
6. Pressure tank and associated air control
system
7. Recycle pump
8. Compressor
9. Recycle piping
Chart I lists the operating horsepower included in the above
described unit. Based upon a 10 hour per day, 5 day per week
operation, costs of running the Model No. 6020 for 52 weeks Is
shown for electrical costs at $0.01 per KWH and $0.015 per KWH.
To give a full range of capital costs Involved with steel
package flotation units, the largest unit, Model 9550A, with the
-------
76
CHART I
MODCL GQ2O
/. FLAW M/xeR
2. FLOCCULATOR--
3. SKIMMEB ft
4. BOTTOM SC&EW- • fa
5. GKYCU PUMP — 7'/t
G. COMPReSSOG I'/t
/I.O
BASSO ON IOt4G/QAY, 5QAV/WWK
OPCffAriNQ COST CQUAL
a, *2I4 *o.
-------
77
Treatment of Meat Processing Waste
by Dissolved Air Flotation
same equipment as listed above would cost approximately $57,000.
Our Model 2511, the smallest unit, would cost approximately
$22,000.00, again, with components listed above.
Charts II and III list operating results from units treating
waste of a mixed kill of hogs and cattle and from a ham packing
operation. Charts IV and V are results from our bench scale
testing of different type of meat processing waste and Indicate
degrees of treatment obtained In different methods of treatment.
In several of the preceding results, the use of chemicals
was necessary to meet treatment objectives. Chart II Indicates the
use of a catonlc polyelectrolyte at a dosage of 0.75 mg/1. Based
on the flow of 1600 GPM and a chemical cost of $0.40 per pound,
the cost for the chemical for a 12 hour operation would be a little
less than $3.00 per day. The cost of a simple polyelectrolyte feed
system would be around $6,000.
As Is the case with most Industrial waste, treatabllity
studies should be conducted to determine not only the design para-
meters for a flotation unit, but also to determine If chemical
treatment Is a necessity to meet treatment objectives.
Pilot dissolved air flotation units are
available from most manufacturers for treatability studies. The
rental cost varies, but the normal rate is approximately $500.00
per month.
A laboratory bench scale test procedure has been developed to
simulate the dissolved air flotation process and has been used most
successfully in the determination of design parameters for an air
flotation unit.
-------
78
CHART II
PLANT A
TYPE: HOGS AND CATTLE KILLING
PLOW: 1600 GPM
A. UNTREATED SAMPLE
HEXANE SOLUBLE GREASE ------------------------ 3000 mg/1
B. GRAVITY SETTLING (25 MIN. APPROX. )
HEXANE SOLUBLE GREASE ------------------------ 1200 mg/1
(60* REMOVAL)
C. GRAVITY SETTLING FOLLOWED BY DISSOLVED
AIR FLOTATION WITH CHEMICAL TREATMENT,
33% PRESSURIZED FLOW (TYPE CHEMICAL -
CATIONIC POLYELECTROLYTE DOSAGE 0.75 mg/1)
HEXANE SOLUBLE GREASE ------------------------ 230 mg/1
ADDITIONAL REMOVAL)
(TYPE CHEMICAL - CATIONIC POLYELECTROLYTE
DOSAGE - 0.75 mg/1)
HEXANE SOLUBLE GREASE ------------------------ 80 mg/1
(93% ADDITIONAL REMOVAL)
-------
PLANT B
TYPE: HAM PACKING
NO KILLING
PLOW: 200 GPM - DESIGN
385 GPM - PRESENT
CHART III
79
A. UNTREATED SAMPLE
SUSPENDED SOLIDS
B.O.D.
HEXANE SOLUBLE GREASE
B. DISSOLVED AIR FLOTATION, WITHOUT
CHEMICALS. 33% PRESSURIZED PLOW
SUSPENDED SOLIDS
B.O.D. •—
HEXANE SOLUBLE GREASE
350 mg/1
1100 mg/1
600 mg/1
—— 300 mg/1
(17* REMOVAL)
400 mg/1
(64* REMOVAL)
80 mg/1
(87* REMOVAL)
-------
80
CHART IV
PLANT C
TYPE: HOG KILLING
A. UNTREATED SAMPLE
SUSPENDED SOLIDS • 3700 mg/irComposite
B.O.D. 2800 mg/l{ Removal
HEXANE SOLUBLE GREASE 3300 mg/]>
B. GRAVITY SETTLING (LAB. TIME TO SIMULATE
30 MINUTES FULL SCALE BASIS)
SUSPENDED SOLIDS 800 mg/1
(7»* REMOVAL)
B.O.D. 600 mg/1
(79% REMOVAL)
HEXANE SOLUBLE GREASE 500 mg/1
(85* REMOVAL)
C. GRAVITY SETTLING FOLLOWED BY DISSOLVED-AIR
FLOTATION WITHOUT CHEMICALS, USING 33%
PRESSURIZED RECYCLE FLOW ___
SUSPENDED SOLIDS 440 mg/1
(45* ADDITIONAL REMOVAL)
B.O.D, '• 300 mg/1
(3635 ADDITIONAL REMOVAL)
HEXANE SOLUBLE GREASE 190 mg/1
(62* ADDITIONAL REMOVAL)
D. GRAVITY SETTLING FOLLOWED BY DISSOLVED-AIR
FLOTATION WITH CHEMICAL TREATMENT USING
200 mg/1 OF ALUM AND 1 mg/1 OF ANIONIC
POLYELECTROLYTE
SUSPENDED SOLIDS • 230 mg/1
(71% ADDITIONAL REMOVAL)
B.O.D. 210 mg/1
(65% ADDITIONAL REMOVAL)
HEXANE SOLUBLE GREASE 55 mg/1
(88* ADDITIONAL REMOVAL)
NOTE: RESULTS ARE FOR BENCH SCALE TESTING
-------
81
CHART V
PLANT D
TYPE: LAMB
KILLING
A. UNTREATED SAMPLE
HEXANE SOLUBLE GREASE 2600 mg/1
(GRAB SAMPLE)
B. DISSOLVED AIR FLOTATION, WITHOUT
CHEMICALS. 33* PRESSURIZED FLOW
HEXANE SOLUBLE GREASE 104 mg/1
(96% REMOVAL)
C. DISSOLVED AIR FLOTATION, WITH
CHEMICALS, 33? PRESSURIZED FLOW
(TYPE - CATIONIC POLYELECTROLYTE
DOSAGE - 0.75 mg/1)
HEXANE SOLUBLE GREASE 76 mg/1
(97% REMOVAL)
NOTE: RESULTS ARE FOR BENCH SCALE TESTING
-------
82
Treatment of Neat Processing Waste
by Dissolved Air Flotation
This flotation test ( see photographs -) Is used to
determine the suspended particle rise rate (VT) which Is the most
critical design parameter In the design of the flotation unit.
This Is done by filling the pressure cell with liquid^and to
closely simulate the recirculation of the unit effluent of
pressurlzatlon In a full size unit, the recycle water should be
developed by several previous flotation runs. This liquid is then
injected with air until a pressure of over 40 psl is obtained and
then the cell is shaken vigorously to assure that the air is put
into the solution. The pressurized liquid is then Introduced into
the waste. The exact amount of pressurized liquid is determined
by trial and error for best results. As the minute bubbles are
released from solution, they attach to the suspended particle and
oil and rise to the surface. After flotation is complete, a
sample of the effluent is then taken and analyzed. During the
test, observation of the rise rate of the major portion of the
solid material with respect to time is recorded. From a graphical
plot of this data a rise rate can be calculated. This rise rate
along with factors for turbulence and short-circuiting are used in
the selection of the basin size necessary to accomplish treatment
required.
-------
PRODUCT MANUAL - SANITATION EQUIPMENT /^-^\
CONVEYOR and PROCESS EQUIPMENT DIVISION (RE2L)
^Z^H/^%kl f^^J BELT COMIf»JkMV MILWAUKEB 1. MflSCOMSIM ^^--,^^r
SECTION
SUBJECT
(1 0) FLOAT - TREAT
DEMONSTRATION PROCEDURE FOR
REX FLOAT - TREAT TEST KIT
Data Sheet No.
315- 10. 801
Page 1 of 5
Issued
November 30,
1955
Supersedes
See Figure 2 - Data Sheet 315-10. 804 for Rex Float-Treat Test Kit.
A. Assume that a recirculation ratio of 0. 33/1 is to be tried.
1. Place 750 ml of a representative sample of the waste in a one liter
graduated glass cylinder. (See Figure 3, Data Sheet 315-10. 804.)
2. Fill the Float-Treat Pressure Cell approximately three-fourths full
with liquid. (See Figure 3, Data Sheet 315-10. 804. )
(It is desirable that the operation of the Float-Treat
Pressure Cell closely similate the recirculation of
effluent as used in the Float-Treat Flotation System.
The returned effluent (recycle water) may be developed
by repeated flotation of several different portions of raw
waste. After the recycle water has been developed and
used in the flotation tests, samples may then be withdrawn
for chemical analyses.)
3. Secure the cover gasket and cover of the Float-Treat Cell, making
certain all the valves are closed.
4. Inject air into the cell until a pressure of 40 psi is attained and
maintained during testing. (See Figure 4, Data Sheet 315-10. 804.)
5. Shake the cell vigorously for thirty seconds.
6. Release 250 ml of the liquid which has been pressurized into the
graduated cylinder. (See Figure 5, Data Sheet 315-10. 804.) The
volume of liquid in the graduated cylinder then totals 1000 ml
(750 ml raw and 250 ml pressurized). The ratio of volumes of
recycle water to the raw waste is termed the recycle ratio. This
ratio is expressed in percent and is termed the recycle rate. Thus,
the recycle rate used in this test is 33%. The most suitable recycle
rate can be determined by repeated tests at varying rates of recycle
and usually is not less than 20% and no more than 50%. To facilitate
the introduction of the air-charged recycle water to the graduated
cylinder, a rubber tube may be connected to the petcock on the
pressure cell. After clearing the rubber tube of air, (Allow some
liquid to escape through the tube by opening petcock. Sufficient
liquid should be removed until it has a milky appearance) the air-
charged recycle water is introduced through the rubber tube into the
graduated cylinder. The end of tube should be placed near bottom of
the cylinder. (See Figure 5, Data Sheet 315-10. 804.)
Form 271-S C. B.Co.
-------
PRODUCT MANUAL - SANITATION EQUIPMENT x-^^x
CONVEYOR and PROCESS EQUIPMENT DIVISION (PEY)
CZ^HI/^.1 I^U OELT COMI»J»MV MII.WAUICBB 1, WISCONSIN \Ja£S>^'
SECTION
SUBJECT
(10) FLOAT - TREAT
DEMONSTRATION PROCEDURE FOR
REX FLOAT - TREAT TEST KIT
Data Sheet No.
315- 10. 802
Page 2 of 5
Issued
November 30,
1955
Supersedes
The air bubbles rise through liquid in a manner similar to that in
the Float-Treat flotation system.
7. Allow the contents of the graduated cylinder to come to rest and
observe the flotation. (See Figure 6, Data Sheet 315-10. 805. )
Allow sufficient time for the rising solids to come to the surface
of the liquid. Usually ten minutes will be sufficient time for the
flotation to be completed. (See Figure 7, Data Sheet 315-10. 805. )
8. After the flotation is completed, a sample of the raw waste and
treated waste should be taken for analysis. (See Figures 8 and 9,
Data Sheet 315-10. 805. ) The treated waste should be carefully
withdrawn from the graduated cylinder either through the use of
a petcock installed in the side and near the bottom of the cylinder
or through the use of a siphon inserted in the cylinder. Sufficient
liquid should be withdrawn to complete the desired analysis, how-
ever, care should be taken to avoid the break up of the skum blanket.
9. Should chemical flocculation with flotation be desired, the chemical
may be added into the raw waste after step "l" is completed, floc-
culation may be carried out, for convenience, in another vessel.
Care should be taken not to break up the floe when transferring the
waste to the cylinder. Enough time for flocculation should be allowed
before introducing the air-charged recycle water. Under appropriate
conditions, a floe may be formed by gentle agitation of the waste
after the chemical is added. The procedure described above also
applies when chemical flocculation is used. When using chemical
flocculation, care should be exercised not to break up the floe par-
ticles in handling the flocculated waste.
Because of the peculiarities of some floe formations, they will break
up readily upon any excessive agitation after being formed. This is
most readily noticed when a liquid with a preformed floe is transferred
from the cylinder used in the jar mixing test to the cylinder used in
the flocculation test. If the floe does break up and does not re-form
immediately, it is suggested that the transfer to the flotation cell not
be made and that flotation be accomplished in the vessel where the
floe was formed. The procedure for running this test are the same.
However, withdrawing of the clarified liquid, as described in step "8",
will probably be through a siphon.
Form 271-S C.B.Co.
-------
PRODUCT MANUAL • SANITATION EQUIPMENT ^^>.
CONVEYOR and PROCESS EQUIPMENT DIVISION (RE3t)
O^l-i/^^l FNJ BELT COMPANY MH.WAUKH 1. WiSCOMSIM ^o-^/
SECTION
SUBJECT
(10) FLOAT - TREAT
DEMONSTRATION PROCEDURE FOR
REX FLOAT - TREAT TEST KIT
Data Sheet No.
315- 10. 803
Page 3 of 5
Issued
November 30,
1955
Supersedes
In flotation of a particular waste, it is quite possible that the test using
the recirculation ratio of 0. 33/1 may not yield the best results. It
may be that some other recirculation ratio would yield the results
needed to work in with the economy of a final plant design and effluent
requirements. Therefore, the tests described above may be repeated
with other recirculation ratios until the optimum ratio is obtained. In
these tests the values shown in steps "l" and "6" will be changed
accordingly.
When running flotation tests in the Rex Float-Treat demonstration kit,
the observed rate of rise of the major portion of the solid material
should be recorded. This value can be recorded in terms of inches per
minute and will be used in determining the full scale plant requirements.
In order to insure the validity of results obtained, care should be taken
that representative samples of waste are obtained before running tests.
When results have been obtained, they should be recorded on Question-
naire for Design Data Sheets 315-10. 101 and 315-10.102. These
completed sheets should be returned to CHAIN Belt Company.
Form 271-S C.B.Co.
-------
PRODUCT MANUAL - SANITATION EQUIPMENT
CONVEYOR and PROCESS EQUIPMENT DIVISION
BELT COMI»JIMV MILWAUKEE I. MMSCf
Data Sheet No.
315- 10. 804
Page 4 of 5
SECTION
(10) FLOAT TREAT
I ssued
November 30, 1955
SUBJECT DEMONSTRATION PROCEDURE FOR
REX FLOAT - TREAT TEST KIT
Supersedes
.-,;.T
. T-/UK
'•: L
• -
oal.
'
Form 271-S C.B.Co.
-------
PRODUCT MANUAL - SANITATION EQUIPMENT
CONVEYOR and PROCESS EQUIPMENT DIVISION
BELT eOP«f»J»t*V MILWAUKEE I. WISCONSIN
Data Sheet No.
315- 10. 805
Page 5 of 5
SECTION
(10) FLOA T TRE A T
Issued
November 30, 1955
SUBJECT DEMONSTRATION PROCEDURE FOR
REX FLOAT-TREAT TEST KIT
Supersedes
••~ 7
rr -RAWN
Form 271-S C.B.Co.
-------
83
li. Other Systems: Whereas the preceding section nas limited to a
discussion of rectangular dissolved air flotation
systems, it should be noted that the same principles sore applied to
circular-shaped tanks by a number of equipment manufacturers. These
tanks are similar to conventional clarifiers with center baffled inlet,
peripheral weir, bottom sludge removal scrapers, and surface skimmer
arms discharging to a surface scum trough. The pressurized air recycle
arrangements are the same act those used in rectangular tank systems.
These circular systems average approximately $1,200 per foot of diameter
to 20 ft. in diameter, and $1,000 per foot of diameter above 20 ft.
These costs include steel tank side sheets, the sludge and scum removal
mechanism, pressurizing pump, y
-------
830 01 73-1
Westinghouse Infilco
Typical flow sheets
meat packing and
processing industry
Air Saturation Tank
Air
40-60 PSI
Pressurizing
Pump
Sump or Primary
Skim Tank
5 30 Min Retention Time
Effluent to Discharge
or Further Treatment
Air
40-60 PSI
Sump or Primary
Skim Tank
5--30 Min Retention Time
Effluent to Discharge
or F urther Treatment
III
Air
40-60 PSI
Screen
•*•
Sump or Primary
Skim Tank
Press
Pump
•£?
5—30 Min Retention Time
Effluent
to Discharge or
Further Treatment
Air Saturation
Tank
Westinghouse Electric Corporation
Infilco Division Box 2118 Richmond, Va. 23216
Printed in USA
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Westinghouse Infilco
830 0173--2
Typical flow sheets
meat packing and
processing industry
IV
Air Saturation Tank
Air
40-60 PSI'
Press Pump
Sump or Primary
Skim Tank
Effluent to Discharge
or Further Treatment
5- 30(Win Retention Time
5 Win Retention T ime
Air Saturation Tank
Air
40-60 PSI
Treatment Chemicals
Screen
-^
Sump or Primary
Skim Tank
5-30 Min Retention Time
Press Pump
50% Recycle
Effluent to
Discharge or
F urther T reatment
5 Min Retention Time
Westinghouse Electric Corporation
Infilco Division Box 2118 Richmond, Va. 23216
Primed in USA
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INFILCO SEDIFLOTOR® CLARIFIER
'H* SCUM OUTLET
WEIR ADJU8TIN9 NUT
LADDER
"F" EFFLUENT
•ROUT AFTER TANK
FiATE* WELDED
IN PLACE
D* INFLUENT
(BY OTHERS)
IOE LINE V
PLAN I (BY OTHERS)
*r*EFFLUENT
•E" RECYCLE OUTLET
DETAIL V
*a' SLUD8E LINE
(BY OTHERS)
ELEVATION
DIMENSION
A
B
C
D
E
F
6
H
I
J
K
L
TANK DIAMETER
SIDESHEET HEIGHT
SIOESHEET THICKNESS
INFLUENT
RECYCLE
EFFLUENT
SLUDGE BLOWOFF
SCUM OUTLET
SLUDGE SUMP, WIDTH
SLUDGE SUMP. DEPTH
NUMBER OF SKIMMERS
DRIVE HORSEPOWER
Westinghouse Electric Corporation
Infllco Division
ND 831 A
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The following data is reported for these systems:
SYSTEM
PLANT PRODUCT HEAD per DAY FLOW SHEET CAPACITY
gpm
DIAMETER
FLOTATION UNIT
A Beef
C Beef
J Pork
1100
1000
300
Operating Results Reported from these
PLANT CHEMICALS
ADDED
A None
C None
J —
A —
C None
J Fe2 (SQ^
A —
C None
J Fe2(SQ1|)3
POLLUTANT
Grease
Grease
—
—
BOD
BOD
—
Suspended
Solids
Suspended
Solids
I
I
V
Plants j
INFLUENT
mgA
1150
21^0
—
— —
1710
1306
—
6200
1380
1000
1500
100
EFFLUENT
mgA
150
213
—
— -
760
200
—
lao
60
35t-o"r
50»-0'"
171-6"
% REMOVED
87
90
—
—
55
85
_
93
;95
There are numerous other proprietary devices, processes and mechanical
details for which claims are made to enhance the efficiency of gravity separ-
ation and dissolved air flotation •— too many to recount here. Again, it
must be stressed that the system must operate, in pilot scale, on the waste-
waters _prom the packing plant for several months before its value can be
established for the particular plant in question.
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IV. CASE HISTORIES in TftSTE CONSERVATION and PRETREATMENT
A. A hog killing plant of medium size in Iowa, producing fresh pork with
no further processing other than edible and inedible rendering, has, mainly
by way of water conservation, reduced BOD to 2.5 to 3«0 Ibs. per 1000 Ibs.
live weight kill. The plant kills about 5oU,000 ibs. live weight using
only 58,000 gallons of water. Peak kill reaches 5U*,000 Ibs. and peak water
use 78,000 gallons per day, with a minimum of 33,000 gallons on any operation-
al day.
Yards and pens are all dry cleaned, using a manure spreader for direct
disposal on farmland. The blood floor is pre-rinsed with a small diameter
hose equipped with a fan nozzle using water at 600 Ibs. pressure. The small
amount of rinse water, 35 to 50 gallons per day, goes to the blood tank. All
blood is dried. The extra drying cost for the pre-rinse water is small com-
pared to the cost saving in BOD reduction in final cleanup.
The plant is equipped with edible and inedible dry rendering, but paunches
and edible stomachs are washed, and the wastewater is discharged to the sewer.
The possibilities of further improvement in waste conservation by dry dumping
have not been explored.
The plant produces a substantial saving in solids and BOD by their pro-
cedure in dumping the scalding tub. The tub is fitted with a drain 6 inches
above the bottom of the tub, draining through a 2-inch line. The slow drain
permits the sludge to settle. Then the residual sludge is scraped and shovel-
led to a large sluice gate that is kept closed during drainage. The sludge
is hauled to farm fields.
The de-hairing operation uses only 6 gallons per hog at 250 hogs per hour,
with five men shaving and trimming. The wet hair is sold.
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86
The grease sewer discharges to a small gravity catch basin 5 ft. wide
and 6.J> ft. long, with a sloping end. A single scraper chain mechanism
serves to drag the bottom sludge up the sloping end to a trough and also
pushes the scum to a scum trough. The scrapers ride up a beach at the scum
trough and thence over the trough to complete the circuit. Bottom solids
and skimmings go to rendering.
The effluent of this basin joins the non-grease sewer at a 12 ft. dia-
meter holding sump, from which & UOO gpm pump discharges to a circular dis-
solved air flotation unit also rated at UOO gpm. Recycle is one-part recycle
to four-parts raw flow. No chemicals are used. The effluent flow is then
discharged to a portion of the pump sump, walled off to carry the effluent
to lagoon treatment (the wastewater could be considered ready for discharge
to a city sewer at this point). The walled portion of the pump sump is
arranged to recycle effluent through the flotation unit, during low flow
periods, to insure uniform treatment in the flotation unit.
The plant is washed down by a contract janitorial service, after plant
personnel dry-clean the floors and equipment to remove scraps. The initial
rinse on the blood floor is done by plant personnel. All dryers are equipped
with sprays for cleaning-in-plaoe (CIP).
i
The owner gives major credit to water conservation for his overall
success in reducing BOD as well as Hater consumption.
It should be noted that the operations at this plant are limited to
slaughtering and rendering. Since individual process wastes in the meat
industry have not been systematically evaluated, it is impossible to predict
the effect of additional processing on the results of these wastewater con-
servation data.
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87
B. A large meat packing plant, killing U70,000 Ibs. live weight beef
and 1,380,000 Ibs. live weight hogs, operates a complete pork processing
system, including smoking, sausage manufacturing and curing, as well as
sliced luncheon meat, canned meats and lard manufacturing. It discharges
less than 1; million gallons of wastewater daily and recycles 1,100,000
gallons of wastewater daily for various pruposes in the plant. Blood is
coagulated and the bloodwater is evaporated. Hides are sold green. Three-
quarters of the hog hair is sold, the remainder going to landfill. Paunches
are washed and the manure is removed from the wastewater by screening before
joining the major wastewater stream. They operate a laundry for shrouds and
work clothes, and washing facilities for all rail cars. Tripe and stomachs
are washed but casings and chitterlings are tanked direct. Viscera are
hashed and washed. Wet rendering is practiced for continuous edible render-
ing and for inedible rendering of skimmings. Pretreatment consists of screens,
gravity catch basins and dissolved air flotation. Manure sewer wastewaters
are separately screened. The raar BOD is 1600 mg/1, suspended solids 1700 mg/L
and grease 800 mg/1. After pretreatment, these respective data drop to
850 mg/1 (kl% BOD removal), 500 mg/1 (11% suspended solids removal), and
150 mg/1 (8l# grease removal).
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V. SUMMARY
In any effort to improve the quality of the wastewaters from a meat
packing plant, the first step must be a complete evaluation of in-plant
waste conservation opportunities. These include recovery of product; re-
moving solid wastes and inedibles at the source (dry, whenever possible)j
recycling waters such as cooling water and can quenching; and reuse of
wastewater for inedible purposes such as condenser water in the tank house*
These and others are detailed in this manual.
In the offing, and possibly already inaugurated in many communities, are
new regulations setting forth pretreatment requirements and surcharge systems
to charge back to the meat packer those costs of municipal treatment for which
he is responsible* The cost of purchased water, plus the cost of waste treat-
ment (pretreatment costs plus municipal surcharges) and possibly the value of
recoverable by-products offer economic incentives for waste conservation.
After all feasible steps in waste conservation have been taken, the degree of
"pretreatment" of the various waste flows must be determined, first to satisfy
regulations and second, to determine whether pretreatment beyond that required
legally will produce economic advantages. Whereas the basic pretreatment will
be required by law, any pretreatment beyond this base is an economic decision.
Thus there is an economic breakpoint where the pretreatment can stop. Possibly
the legal requirements are the stopping point and nothing can be gained by
going further.
Other variables enter the pictures the possibilities for increases in
municipal surcharges; the adequacy of the municipal plant to treat the waste-
waters, and the general growth potential of the community, both in industry
and in population. The meat packer mast also consider his own future business
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89
plans, such as changes in processing, additional processing, overall expansion,
or possibly, reduction in operations. If wastewaters are treated try the packer
for direct discharge to a watercourse, he must consider obsolescence of the
treatment plant, possible changes in legal requirements and the costs that are
part of a -wholly owned facility (taxes, maintenance, operation, amortization, etc.).
Within these elusive variables, the meat packer must determine:
1. The amount of in-plant waste conservation he should economically
undertake. It should be noted here, however, that a substantial amount of waste
conservation can often be accomplished at insignificant expense.
2. The degree of pretreatment (for each of the segregated plant waste
streams) that he should undertake in order to arrive at an economic breakpoint.
For example, he may find that a small amount of biological treatment, beyond the
physical and chemical treatment discussed in this manual, will drop the BOD and
suspended solids to a level equivalent to domestic sewage, and surcharges that
the city has levied based on plant wadctewater concentrations beyond the level
of domestic sewage will drop to zero.
3* Whether the long-range possibilities for increases in municipal
surcharges may warrant consideration of a completely independent wasterrater
treatment system, discharging to a watercourse, thereby eliminating all depend-
ence upon the municipal system.
Most of the biological treatment systems discussed in the section of this
seminar on "Treatment for Discharge to a Watercourse1* are also applicable to
treatment prior to discharge to a city sewer, should such treatment become
necessary to satisfy municipal regulations or become economically feasible.
The following outline suggests procedures for developing a decision matrix
for waste conservation and pretreatment prior to discharge to a public sewer:
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1. Employ a waste conservation supervisor. In a small plant, he may
have other duties such as safety engineer and have responsibility for com-
pliance with Occupational Safety and Health Act (OSHA). In a large plant,
a full-time waste conservation supervisor should be employed. He should have
some engineering background, preferably in environmental engineering. He
will be responsible for waste conservation surveys, flow measurement, sampling
surveys, cost analyses of waste conservation and treatment and continuing
surveillance of the waste conservation and treatment program, including super-
vision over the operation of any treatment facilities.
2. Install flow measuring and automatic sampling to collect and analyze
wastewater samples at sufficient frequencies and over a sufficient length of
time to develop data on flow during the wfladnnvn hour and the maximum day, as
well as averages.
3. Make an in-plant waste conservation survey as detailed in this manual.
Develop annual costs for each possible change to include:
a. Amortized cost of improvements, installed.
b. Power costs such as heating, cooling, and pumping for
recycling and water reuse.
c. Chemical costs if some in-house treatment is required in
recycling & waste stream.
d. Labor cost (maintenance and operation).
li. Make a study of possible pretreatment systems, with annual costs
developed as in item 3 above*
5. Determine the annual cost of municipal surcharges if wastewaters are
discharged to the city sewers, and select in-plant improvements on a comparative
cost basis. If wastewaters are discharged to a private treatment facility for
disposal to a watercourse, the same type of cost analysis should be made.
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6. Select the elements of 3 and U that are economically justified.
7. Design selected improvements to achieve the required results,
considering such elements as:
a. Flexibility, for alteration and expansion.
b. Operating skills required.
c. Quantity of residual solids and grease and feasible means of
disposal.
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92
VI. APPENDIX
APPENDIX A: REFERENCES
(1) "Industrial Waste Profile No. 8 — Meat Products."' Seriesi
The Cost of Clean Water, Federal Water Pollution Control
Administration (196?) p. 53.
(2-) Witherow, J. L., "Meat Packing Waste Management Research
Program", 65th Annual Meeting, American Meat Institute,
Chicago, 111., (October 1970).
(3) Gurnham, C. F. (Ed.), Industrial Wastewater Control,
(Johnson, A. S., "Chap. 2. Meat"1). Academic Press, New York
(1965) p. 36.
(U) Beefland International, Inc., Elimination of Water Pollution
by Packinghouse Anlmal Paunch and Blood, EPA Proj.: 12060
Fds (Nov. 1971).
(5) Dencker, D. 0., "Some Solutions to Packinghouse Waste Problems."
Presented at 15th Wastes Eng'g Conf., Univ. of Minn. (Dec. 1968)•
(6) Wells, W. J., Jr., "Hcrw Plants Can Cut Waste Treatment Expense."1
The National Provisioner (July h, 1970).
APPENDIX B: BIBLIOGRAPHY. In addition to the above references, cited in the text
of the Manual by number, the folio-wing sources may be
useful:
1. , "An Industrial Waste Guide to the Meat Industry."'
U.S. Public Health Service Publication No. 386. Revised 1965.
2. Brammer, H. C. and Motz, D. J., "An Overview of Industrial
Water Costs."' Industrial Water Engineering (March 1969).
3. Miedaner, W. H., "In-Plant Wastewater Control." Presented at
Univ. of Wis, Extension Program, Wastewater Treatment in the
Meat Industry (April 1972).
k» Miedaner, W. H., "In-Plant INkste Control." The National
Provisioner (August 19, 1972).
5. Nemerow, Nelson Leonard, Theories and Practices of Industrial
Waste Treatment, Syracuse, N. Y., Addison-Wesley Publ. Co. inc.
(1963).
6. Steffen, A. J., "Waste Disposal in the Meat Indus try, • A Compre-
hensive Review."; Proceedings, Meat Industry Research' Conference,
American Meat Institute Foundation, Univ. of Chicago (March 1969).
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APPENDIX C
LIST of EQUIPMENT TRADE NAMES*
The following is a list of trade names of the equipment discussed in
this Manual. The types of equipment are listed in the order in which they
are presented. Any mention of products or services here or elsewhere in
the Manual is for information only, is not selective unless it is used to
illustrate a point, and is not to be construed as an endorsement of the
product or service by the EPA or the authors.
Although the lists are intended to be complete, some oversights may
have crept in. Such oversights are not to be construed as reflecting on
the merits of the product or service.
The author will appreciate being advised of errata, in order to improve
subsequent editions of this list.
BLOOD COAGULATION PREVENTION SYSTEM.(Sect. II E).
Chemical and Eng»g Group (Swift Research & Development Laboratories)
STATIC SCREENS (WEDGE BAR) (Sect. Ill C 2).
Bauer Hydrasieve
Dorr-Oliver
Hendricks
Hydrocyclonics
Peabody Welles
Static Sieves (F. J. Clawson & Assoc., Inc.)
VIBRATING SCREENS (Sect. Ill C 3).
Allis Chalmers
DeLawal
Envirex
Link Belt
"Belectro", "Gyroset", n
-------
9h
ROTATING DISC SCREENS (Sect. Ill C 1|).
Envirex
Link Belt
ECCENTRIC-WEIGHTED HORIZONTAL DISC SCREENS (Sect. Ill C U).
Aero Vibe (Allis Chalmers) Kason
Sweco
Hydrocyclonics Syncro—Matic (Eriez)
CENTRIFUGES. (Sect. Ill C lib).
Beloit Dorr-Oliver "Merco Bowl"
Bird Eimco (Envirotech Corp.)
DeLaval Sharpies (Pennwalt Corp.)
GRAVITY GREASE RECOVERY & SEPARATION (Sect. Ill D 2-).
Belco Envirotech
Beloit-Passavant Graver
Carter Hardinge
Chicago Pump Infilco
Cloir Yeomans Jeffrey
Crane Keene
Dorr-Oliver Lakeside
Dravo Link Belt
Envirex Walker Process
Environmental Services Zurn
DISSOLVED AIR FLOTATION (Sect. Ill D 3 and k) (Rectangular and/or Circular).
Aeroflotor (Graver) Infilco
Beloit-Paa savant Keene
Black-Clawson Komline-Sanderson
Envirex Pacific (Carborundum Co.)
Environmental Systems Permutit
Envirotech
For addresses, see following pages.
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95
ADDRESSES of MANUFACTURERS
of Trade Name Items
Listed in Preceding Pages
Allis-Chalmers HTg.Cc>.
1126 S. 70th St., Milwaukee, Wis. 5321U
Bauer Bros* Co., Subsid. Combustion Eng'g. Inc.
P.O. Box 968, Springfield, Ohio U5501
Belco Pollution Control Corp.
100 Pennsylvania Ave., Paterson, N.J. 07509
Beloit-Passavant Corp.
P.O. Box 997, Janesville, Wis. 535^5
Bird Machine Co.
South Walpole, Mass. 02071
Black-Clawson Co.
Middletown, Ohio li5oU2
Carborundum Co.
Buffalo Ave., Niagara Falls, N.Y. Iii302
Carter, Ralph B., Co.
192 Atlantic St., Hackensack, N.J. 07601
Chicago Pump Div., FMC Corp.
622 Diversey Parkway, Chicago, ELI. 6o6lU
Clawson, F. J. & Assoc.
6956 Highway 100, Nashville, Tenn. 372O5
Clow Corp., Waste Treatment Div.
1999 N. Ruby St., Melrose Park, HI. 60160
Crane Co., Environmental Systems Div.
Box 191, King of Prussia, Penn. 19U06
DeLaval Separator Co.
Poughkeepsie, New York 12600
Dorr-Oliver, Inc.
Havemeyer Lane, Stamford, Conn* 0690U
Dravo Corp.
One Oliver Plaza, Pittsburgh, Penn. lf?222
Envirex, Inc., A Rexnord Company, Water Quality Control Div. (formerly RexChainbelt)
1901 S. Prairie, Waukesha, Wis. 53186
Environmental Services, Inc.
1319 Mt. Rose Ave., York, Penn. 171*03
Environmental Systems, Div. of Litton Industries, Inc.
3Sh Dawson Drive, Camarillo, Calif. 93010
Envirotech Corp., Municipal Equipment Div*
100 Valley Drive, Brisbane, Calif. 95005
Eriez Synchro-Matic
lliOl Magnet Drive, Erie, Penn. 16512
Graver, Div. of Ecodyne Corp.
U.S. Highway 22, Union, N.J. 07083
Green Bay Foundry and Machine Works
Box 2328, Green Bay, Wis. 5U306
Hardinge Co., Metal Products Div., Koppers Co., Inc.
York, Penn. 17li05
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96
Hendricks Mfg. Co.
Carbondale, Perm. 18U07
Hydrocyclonlcs Corp.
968 North Shore Drive, Lake Bluff, m,
Infilco Division, Westinghouse Electric Co.
901 S. Campbell St., Tucson, Ariz.. 85719
Jeffrey Mfg. Co.
961 N. Uth St., Columbus, Ohio U3216
Kason Corp.
231 Johnson Ave., Newark, New Jersey 07108
Keene Corp., Fluid Handling Division
Cookeville, Tenn. 38501
Koraline-Sanderson Engineering Corp.
Peapack, New Jersey 07977
Lakeside Equipment Co.
1022 E. Devon Ave., Bartlett, 111. 60103
Link belt Environmental Equipment, FMC Corp. (Gravity and Flotation)
Prudential Plaza, Chicago, 111. 60601
Link Belt Material Handling Division, FMC Corp. (Screens)
300 Pershing Road, Chicago, Hi. 60609
Peabody Welles
Roscoe, 111. 61073
Pennwalt Corp., Sharpies-Stokes Division
955 Mearns Road, Warrainster, Perm. I897li
Permutio Co., Div. of Sybron Corp.
E. U9 Midland Ave., Paramus, New Jersey 07652
Productive Equipment Corp.
292l| W. Lake St., Chicago, 111. 60612
Simplicity Engineering Co.
Durand, Mich. U8U29
Sweco, Inc.
6033 E. Bandini Blvd., Los Angeles, Calif. 9005U
Swift Research & Development Laboratories, Chemical & Eng'g Group
119 Swift Drive, Oak Brook, 111. 60521
Walker Process Equipment, Inc., Div. Chicago Bridge & Iron Co.
Box 266, Aurora, 111. 60§07
Zurn Industries, Inc.
1U22 East Ave., Erie, Penn. 16503
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