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TABLE OF CONTENTS
I. INTRODUCTION: A. J. Steffen
A. Why Pretreatment?
B. When Pretreatment?
C. How Pretreatment?
Do Costs
II. SCREENING
A. Introduction: A. J. Steffen
B. Vibrating Screens: Dan M. LLndenmsyer, Tech. Spec., Vib. Screens
Link Belt Mot. Handling Equip. Dlv., BtC Corp.
C. Wedge Bar Stationary Screens: II. E. Ginaven, V.P., Prod. & Processes
The Bauer Bros. Co.
Subsid. Combustion Eng. Inc.
D. Rotary Screens & Other Screening Devices: A. J. Steffen
III. SEPARATION OF GREASE & SUSPENDED SOLIDS
A. Gravity Grease Recovery & Separation: Robert Johnson, Reg. Eng.
Envir. Equip. Div., FMC Corp.
B. Pressurized Air Flotation: Charles Grimes, Envir* Control Group
Rex Chainbelt Inc.
C. Other Systemst A* J. Steffen
IV. SUMMARY: A. J. Steffen
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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
various items of data to round out the material
presented.
A. J. Steffen
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PREFACE
This brochure is intended to serve as an information medium for one
section of the Environmental Protection Agency Technology Transfer Design
Seminar for Upgrading Poultry Processing Facilities to Reduce Pollution.
This section relates to "Pretreatment for Discharge to Municipal
Systems'* and represents a half-day's session of the seminar. The other
two sections cover in-house waste conservation and re-use, and complete
treatment for discharge to a watercourse. Separate brochures to cover
these two subjects are provided at this seminar. The material is oriented
toward plant owners, managers, superintendents and their engineering and
operating staffs.
Wherever possible, copies of visual aids used during the presentations
are reproduced herein. The selection of speakers 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 the pro-
prietary material presented herein, does not directly or indirectly imply
an endorsement of such product.
Most poultry plants are now using flowaway systems, thus the subject
matter relates largely to this type of waste handling system. The custom-
ary screens used in flowaway systems to remove offal and feathers are
intended to improve the wastewater for re-use in the processing plant and
for recovery of by-products and are thus not considered (herein) as part
of pretreatment for discharge to a municipal system. However, it is recog-
nized that effluent may often be improved by improvements in flowaway
screening.
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Pr-,-4
Pretreatmsnt does not include treatment of sanitary wastes (normally
discharged directly to the city sewer), storm water, cooling water, or
condenser water.
Disposal of the recovered screenings, floatables and settled solids
is beyond the scope of this brochure, but concentration of the f Loatablcr:
and settled solids by screening to reduce liquid content is included.
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I. INTRODUCTION! A. J. Steffen
A. Why Pre-treatment?
In this portion of the seminar, we are concerned with the troatmont
of poultry wastes after the customary screening in flowaway systems and
prior to discharge to a municipal sewer. We will use the term "pretreat-
ment111 to cover all physical, chemical or biological treatment provided for
this purpose.
The majority of poultry plants discharge to municipal sewers. In a
1971 USDA survey (see Bibliography, Item 11) of 386 poultry plants, almost
two-thirds were connected to some type of public sewer system. The survey
did not show how many had pretreatment. Whether or not pretreatmant is
required at a poultry plant depends most frequently upon municipal regula-
tions regarding some of the ingredients in the poultry wastes. Ingredients
such as feathers may be prohibited because they cannot be efficiently re-
moved and disposed of in conventional municipal sewage treatment plants,
while other ingredients, such as solids may be subject to special charges
to defray the expense of their removal and disposal in the municipal system.
Federal regulations covering grants-in-aid to municipalities touch on
pretreatment of industrial wastes. The EPA has set up rules relating to
industrial wastes discharged to such municipal systems, as noted in the fol-
lowing excerpt from the Federal Register of July 2, 1970: "Where project
(for which a Federal grant is requested) is to treat industrial wastes, it
must be included in a waste treatment system treating the wastes of an
entire community. A. waste treatment system means one or more treatment
plants which provides integrated, but not necessarily interconnected waste
disposal for a community, metropolitan area or region. In such a system,
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T-Z
industry must provide pretreatment if waste would otherwise be detrimental
to the system. Where industrial wastes are to be treated in the proposed
project, the Commissioner must be assured that the applicant (municipality
requesting a Federal grant) will have an equitable system of cost recovery".
Thus, if the municipality receives a Federal grant, tho poultry plant
may be required to provide pretreatment if the waste would be detrimental
to the system of municipal treatment. Note also that the cost of treatlnp
the poultry wastes must be recovered in "an equitable system of coat recovery".
In some cases, municipal treatment requirements can be reduced by pretreat-
ment at the poultry plant. This may produce overall savings to the poultry
plant operator, if a cost recovery charge is to be levied.
There are many other instances where pretreatment may become an economi c
advantage. Suppose, for example, that the municipal plant is overloaded and
a plant expansion is contemplated. & study shone that pretreatment at the
poultry plant will eliminate the overload. The decision whether to pretreat
or go along with the municipal plant expansion program depends upon the
relative annual cost (of the two alternatives) to the poultry plant operator.
As another example, suppose that excessive discharges of grease, feathers
or suspended matter are causing special problems in operating primary clnri-
fiers and anaerobic sludge digestion at the municipal plant. The first step
for correction of such problems is waste conservation at the poultry plant
and attention to the flowaway system (check for escape of solids in the flow-
away screen and offal area). If these elements are all in order and good
waste conservation is being practiced in the plant, pretreatraent may be the
next step.
As a further example, suppose the poultry plant management is conaidor-
ing an increase in poultry production or some additional processing. Tho
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added sewage treatment load resulting from such changes can be calculated,
to compare the sewage service charges for municipal plant expansion (made
necessary by the added load), with the cost of pretreatment to produce the
same results.
B. When Pretreatment?
1. Prohibitory and restrictive limits may make pretreatment necessary.
The discharge of some ingredients such as feathers, entrails,
and the like into the municipal system may be completely prohibited.
If the best in-plant conservation practices and careful operation
of efficient flowaway equipment does not eliminate these materials
to the municipality's satisfaction, some form of pretreatment will
be necessary.
On the other hand, restrictive limits (that is, 3j.mits of
concentration of, say, BOD, solids and grease in milligrams per
liter) may vary with the type of municipal treatment. For example,
emulsified fats from poultry cooking operations are amenable to
activated sludge treatment, whereas they may be troublesome in a
trickling filter type plant. A municipality with activated sludge
treatment could then recognize that emulsified fats would be paid
for under BOD charges, with grease restrictions applying only to
floatable grease.
2. Pretreattment nay reduce a poultry processor's overall waste treat-
ment cost when a municipal surcharge system is contemplated.
Surcharge systems vary, and no one can predict whether pre-
treatment can be economically Justified until costs are evaluated.
A surcharge system should be based upon an evaluation, by the city's
consulting engineer, of the cost of the elements of the municipal
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treatment plant necessary to accommodate the flow, remove the
suspended natter and treat the other ingredients of the industrial
wastewater to the required levels, all on a unit basis (cost par
pound of ingredient).
Many surcharge systems start with a flow base rate, and appJy
multipliers for concentrations of such ingredients as BOD, sus-
pended solids, and grease (any or all of these). As an example,
the flow base rate, charged to all sever users, nay be, say, 5u£
of the water bill (flow from private water suppli es would be
included). Then, taking BOD as an example, assume that 250 mg/1
has been established as a bottom base for surcharges» Then a
multiplier might be applied for BOD between, say, 250 and 500 mp/l,
and a higher one between, say, 500 and 1000 ng/1. Another set of
multipliers might be applied for suspended solids, another for
grease, etc. These multipliers are then added together to estabUsh
a single multiplier which is then applied to the flow base charge
to arrive at the total bill.
In other surcharge systems, charges for the pounds per month,
above a base quantity, of BOD, suspended solids and other ingredients
are added to the flow charges based on gallons.
3. Summary.
Except for compulsory action to remove materials prohibited
from entering the city sewers, the degree of pretreatraent is
generally an economic decision. However, since plants differ and
surcharges differ, no simple set of parameters can be established.
Each c&ae oust be evaluated individually not only to establish
present practices but also to prepare for the future.
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C. How Pretreat?
Pretreatment can cover a broad range of wastewater processing elements,
including screening, gravity separation of solids and floatables, pressurised
air flotation, chemical treatment as an adjunct to gravity separation or
flotation, and biological treatment such as aerated or unaerated lagoons or
some other form of aerobic treatment.
Before any pretreatment is considered, an adequate survey should be made,
including flow measurement, composite sampling and chemical analysis to
determine the extent of the problem and the possibilities for pretreatment«
Analyses may include BOD, suspended solids, suspended volatile solids,
settleable solids, pH, temperature, and oils and grease. A permanent flow
measuring and composite sampling arrangement is warranted if sampling is
done regularly to determine municipal surcharges*
Most commonly, pretreatment will consist of separation of floatables
and settleable matter. In some instances lime and alum, or ferric chloride,
or a polymer may be added to enhance separation. Paddle flocculatlon may
follow alum and lime or ferric chloride additions to assist in coagulation
of the suspended solids. Separation may be by gravity or by air flotation.
Screening may precede the separation process, and also may be used to concen-
trate the separated floatables and settled solids. These various systems
will be discussed under separate headings.
Removal of floatables and suspended matter will also accomplish some
reduction in BOD* Frequently this degree of treatment will satisfy municipal
requirements. If additional BOD removal is required, a study of biological
processes for pretreatment may be instituted, possibly in pilot scale.
Several biological treatment systems have been successfully adapted to the
treatment of poultry wastes. Lagoon treatment is discussed in Session 3t
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Direct Discharge to a latex-course. Other BOD removal systems may be suit-
able. The so-called irDutch Ditch", which utilizes an aeration device in an
oval shaped shallow "race-track" ditch to recycle the flow, has boon applied
to meat waste treatment and may be suited to poultry wastes as well. High-
rate aeration, with clarification and sludge return (activated sludge) is
available in many configurations.
A rotating biological contactor is treating the effluent from an air
flotation tank in a pretreatment system at a poultry plant in Illinois. In
the contactor, wastewater flows through a tank in which a series of half-
submerged discs, about 12 ft. in diameter, rotate slowly on a horizontal
shaft. As the shaft turns, a film of biological growth forms on the ro!.;itiri
surfaces. Rotation of the discs alternately passes the bio-maas through the
wastewater where the bio-mass absorbs organic matter, then through the air
where it obtains oxygen for biological metabolism. Excess bio-mass sloughr.
off and is separated in a clarification step. The plant in Illinois treats
130,000 gallons per day and is reported to remove 90% of the BOD in the
wastewater leaving the flotation tank (influent at 2000 rag/l, effluent at
200 mg/1).
Hot«.tl nf. Dl?i<- Contactor
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D. Costs.
Costs of pretreatment depend on many factors, such as size of poultry
plant, type of processing, space available for pretreatment, quality of
in-house waste conservation, pumping requirements, municipal requirement?
regarding quality of effluent, local labor costs, construction costs and
federal and state tax incentives for industrial waste treatment.
However, approximate costs of equipment are given wherever possible,
as well as approximate costs of any chemicals required. Installation costs
of prefabricated systems may be generally estimated at about 30 to 1*0$ of
equipment cost. Processors often prefer prefabricated units for convenience
in installation.
Variations in loading due to changes in processing should not be over-
looked in making rough approximations for sizing pretreatment. For example,
cut-up and packaging can produce 1556 greater BOD than processing to eviscer-
ating only, and fowl can increase grease content from the usual 1.0 to 1«5> Ibs,
per 1000 birds to 1.5 to 2*0 Ibs.
In spite of the wide divergence of costs, some examples of costs of
plants, as built, may be useful. In one recent instance in Arkansas, in a
plant processing $000 broilers an hour, with partial cut-up and packaging
and some deep fat frying, a 20 x 20 mesh vibrating secondary screen (V x 10')
cost $20,000 installed, including a 200 gpm pump. Dual pumps are, however,
advisable and would be expected to add about $1000 to $2000 to this figure.
Another plant in Arkansas, killing, eviscerating, and preparing frozen
dinners, installed pretreatment in 1969, treating 1,250,000 gallons of waste-
water daily. Secondary screening cost $19,500, a vacuator for grease removal
(see in C) cost $1*5*000 and buildings, flumea, piping and controls cost
$259,000 (total $323,500).
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& pro-treatment plant under design for a Georgia processor will cost
$80,000 to $100,000. This will include pumping, and pretreatment to produce
an effluent of 300 fflg/1 BOD and suspended solids and 100 mg/1 fats and
grease. The plant processes 6000 birds per hour and includes eviscerating,
cut-up and packaging*
A screen plus a gravity grease separator, in Canada, treating 330,000
gallons per day from a killing and eviscerating plant, cost $85,500, installed,
without the building.
A pretreatment facility in South Carolina which handles offal and blood
in addition to 2,800,000 gallons of daily flow for a plant killing, eviscer-
ating and preparing frozen dinners oost $278,000 for screening and a vacu-
ator (1965 costs). The building cost an additional $125,000.
The plant in Illinois, described in an earlier paragraph, with air
flotation and revolving disc contactor system cost $80,000. The contactor
alone cost $22,000.
To assist in arriving at rough approximations, Table 1 is included,
showing raw waste loads 0
£. Summary.
The following outline suggests procedures in developing a decision
matrix for pretreatment:
1. Select a project manager. He may be a company engineer or a
consulting engineer, depending upon the extent to which the
study is to progress and the capability of company personnel
to produce the necessary information.
2. Measure flow and collect and analyee oompooite nnmplos <>vur a
period of days sufficient to develop maximum an wull an uvurnc.u
data.
3. Make an in-plant waste conservation survey. The annual cost for
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each possible change should includet
a. Amortized cost of improvements, installed.
b. Power costs (heating, cooling, pumping).
c. Chemical costs (if any)*
d. Labor cost (maintenance and operation).
ii. Make a study of possible pro-treatment systems, with annual costs
developed as in item 3 above.
5. Determine the annual ooat of municipal surcharges and compare with
costs of 3 and U.
6. Select the elements of 3 and b that are economically justified.
7. Design necessary improvements consideringj
a. Portability of system.
b. Flexibility, for alteration and expansion.
c* Operating skills required.
d. Cost of disposal of residual solids and grease.
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TABLE 1 — TYPICAL POULTRY PLANT EFFLUi^T (Untreated)
(Based on Standard Raw Waste Levels (SRWL) from EPA Guide Linen
for Poultry Processing Plants, assuming good irv-plant waste
conservation, flowaway systems with customary flowaway screen-
ing, but no pretreatment).
BROILER PROCESSING
SRWL/1000 Birds
Flow 3000 gal.
BOD** 30 Ibs. (U50 ng/1)
Sus. Solids 23 Iba. (3^5 mg/1)
Dally Discharge
from Typical Plant
Killing 125,000 Birds/day
1,000,000 gals.
3,750 Ibs.
2,870 Ibs.
Pop. Equjv.*
7,700
18,800
Ui,UOO
FOWL & DUCK PROCESSING
SRWL/1000 Birds
Flow
BOD** UO Ibs.
Sus. Solids 25 Ibs.
Daily Discharge
from Typical Plant
Killing 125,000 Birds/day
5,000 Ibs.
3,130 Ibs.
Pop. Equiv.*
25,000
15)', 700
TURKEY PROCESSING
SRWL/1000 Ibs. live Wt. Kill
Daily Discharge
from Typical Plant
Killing 1 million Ibs/day
Pop. Equiv.
Flow 1,700 gal.
BOD** 8 Ibs. (565 fflg/1)
Sus. Solids 5 Ibs. (J*10 ng/I)
**BOD » 5-Day BOD
1,700,000 gals,
8,000 Ibs.
5,000 Ibs.
13,000
Equivalents Based on:
Flow: 130 gal/cap/day
BOD: 0.2 Ibs/cap/day
Stts. Solids: 0.2 Ibs/cap/day
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I-II
I INTRODUCTION — BIBLIOGRAPHY
1. Crosswhite, W. M., Caravan, R. E., and Mac on, J. A., "Water and Waste
Management in Poultry Processing,,11 Proceedings, Second Food Wastes
Symposium^ (Continuing Education Publications, Waldo Hall 100,
Corvallis, Oregon, 97331) 323-335 (March 1971).
2. Camp, W. J., "Haste Treatment and Control at Live Oak Poultry Process-
ing Plant," Proceedings 18th Southern Water Resources and Pollution
Control Conference, North Car,, State University, Raleigh, N. C.
(April 1969).
3. , "Wastes from the Poultry Processing Industry." Tech. Rep, T. R.
W62-3, Dept. of HEW, Public Health Service, R. A. Taft San. Eng.
Center (1962).
k. , "Industrial Waste Profile No. 8, Meat Products.'* The Cost of
Clean Water Series, U.S. Dept. of Interior, Wahington, D.C. (1967).
$. , "Industrial Wastewater Discharges,«" H.Y. State Dept. or Health
(Health Education Service, P.O. Box 7283, Albany, N.Y. 1222lj)
(June 1969).
6. ,"Waste Treatment Lagoons - State of the Art." Water Pollution
Control Research Series 17090 EHXO 7 USEPA (July 1971).
7. Woodward, F. E., Sproul, 0. J., Hall, M. W., and Ghosh, M. M.,
"Abatement of Pollution from a Poultry Processing Plant.1* Water Pollu-
tion Control Federation, Oct. 1971 Meeting, to be published.
8. Layton, R. F., "An Industrial Waste Survey of a Poultry Processing
Plant for Broilers•" Presented at 1971 Purdue Industrial Waste Conf.
(to be published in Proceedings).
9. Decker, Chas. T.j "Rate Surchargest Friend or Foe?ni Water & Wastes
Engineering 8, 11, F2-FU (Nov. 1971).
10. Maystre, Y and Geyer, J. C., "Charges for Treating Industrial Waste-
water in Municipal Plants."1 Journal Water Pollution Control Federation,
U2L 7, 1277-1251 (July 1970).
11. , "The Poultry Processing Industry - A Study of the Impact of
Water Pollution Control Costs." USD! Economic Research Service,
Marketing Research Report No. 965, Prepared for Office of Water
Programs, EPA (June 1972).
12. , "Regulation of Sewer Use"1. Water Pollution Control Federation
Manual of Practice No. 3 (1963).
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II. SCREENING
L. Introduction! A. J. Staffen
In pretreatment, after flowaway, secondary screens may serve for
final polishing with no further pro-treatment, or may precede air flo-
tation systems and gravity separation basins to reduce the bulk of
solids that would otherwise have to be removed in the subsequent units.
Screens vary widely both in mechanical action and in mesh size,
which ranges from 0,5 inch openings in stationary screens to 200 meah
in high speed circular vibratory polishing screens. In some cases the
efficiency of screening in the flowaway systems may be sufficiently
successful to circumvent secondary screening; in others secondary or
polishing screening may be warranted. Floor drains not connected to
the flowaway systems are usually then discharged to this polishing
screen. With no secondary screening, the floor drains in the offal
room and those adjacent to the flowaway screens and offal conveyors
should be pumped back to the flowaway screen influent. These floor
drains are frequently the source of serious problems when difficuJtieh
arise in the flowaway screen systems or conveyors.
In some plants "follow up" stationary screens, consisting of two,
three or four units placed vertically in the effluent sewer before
discharge to the municipal sewer, have successfully prevented escape of
feathers and solids from the drains in the flowaway screen room and
other drains on the premises. However, there is always the temptation
to pull these screens in an emergency. These stationary "channel" scr
are framed, and aro generally constructed of stain] esa ot«oL (rnorh or
pnrf orated), with \ inch to $ inch opontngn. Tho norl PH nrrui»Knnn-n1.
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permits removal of a single screen for cleanup and improves eff1ci ency.
However, these screens may be inadequate to satisfy municipal require-
ments and then secondary (polishing) screening becomes necessary.
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II B. Vibrating Screens; Dan Idndenmeyer
The vibrating screen is a structure with means for producing a rapid
motion with one or more perforated or washed surfaces for separating material
according to si oe. The effectiveness of a vibrating screen depends on a
rapid motion. Vibrating screens normally operate at speeds of 1000 to 2000-RPM
in a notion of 1/32° to
A. successfully operating screen of any type must accomplish a combination
of the following functions:
1. Conveying of Material retained on the screen surface. This must be
done to uncover the opening so that the cloth can pass the undersise
material or liquid.
2. Agitation of the bed of material on the screen surface. Agitation
and stratification are required to open the bed so that the fine
particles or liqjoids can work their way down through the large par-
ticles and pass the opening.
3. Dislodgment of particles which stick or wedge in the opening.
Particles which possess dimensions having nearly the same size as
the opening will clog. Motion of the screen must dislodge the
particles .
U. Distribution of the material in order to take full advantage of the
area of the screen. The material oust be distributed over the surface
to insure efficient screening* Th« motion of the deok should dis-
tribute the material over the deck evenly.
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5. Retention 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.
Following are sons of the advantages of the vibrating screen over the
rotary in handling poultry plant wastes
1. The vibrating screen requires less floor space.
2. The vibrating screen requires less horsepower for operation.
i. Spray water is not normally needed to wash particles from the screen
cloth.
lu The screen cloth required to resurface a vibrating screen is less
than one-third the amount needed for a revolving screen and much
i
easier to install.
5. The initial cost of a vibrating screen is lower in most cases.
6. The vibrating screen produces drier tailings due to its motion.
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.
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When the unbalanced weights are rotated the screen follows the
tiirough a path. When a vibrator is placed on the top of the box, a sLtphL
rocking action will take place, resulting in elliptical motion with the
ellipse leaning toward the vibrator. This notion tends to move the material
away from the feed end 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 longitudinal
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 abusive, wire
of a greater thickness and diameter should be used to assure long life. How-
ever, if the material is light or sticky in nature the durability of the
screening surface nay be the smallest consideration. In such a case, »i light
wire may be necessary to provide an increased percent of open area and more
free screen cloth conditions.
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 #30U stainless steel wire is used. How-
ever, when conditions require other types of metal, special wire cloths can
bu supplied.
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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 1™ distance. If the count does not work out to an even number
the fractional part of the opening should be specified.
The actual opening between the wires is known as "space." Thus, J" space,
.135 wire implies that the wires are £" apart and the diameter of the wire is
.135". We have standardized on a 20 mesh screen for offal and a 36 x hO mesh
screen cloth for feathers and a 36 x UO mesh for pretreatraent. On most appli-
cations a double crimped square weaved cloth is used. Double crimped wire
is woven in a manner so as to arch the shoot wire over the warp and then the
warp wire over the shoot. By doing this, each wire forms a support for the
other, keeping both wires tight and rigid, thus eliminating shifting or slip-
ping of the wire.
We will now see how a liquid dewatering vibrating screen can be used
effectively in the pre-treatment of poultry plant waste for discharge to a
municipal system.
There are many vibrating screens in service in poultry plants throughout
the United States—too many to list. They are installed as feather screens,
as offal screens and as pre-treatment screens for discharge to municipal systems,
The following cost data necessarily is limited to screens we manufacture.
The liquid vibrating screen is manufactured in sizes that vary from ?'0"
wide x li'O" long to U'O" wide x lO'O" long. The most common unit no
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is an NRM-Uj8 liquid dewatering screen. This screen is 14*0" wide x 8<0" long
and as a pro-treatment screen, it is equipped with a 36-mesh x Uo-mesh 30U
stainless steel screen cloth. The unit '•ill handle approximately 600 gallons
per minute of wastewater. An URM open screen complete with stainless steel
screen cloth and drive will cost slightly less than $2,000.X. An NRM-1U8
liquid dewatering screen complete with screen cloth, drive and with feed flume
and tank will cost slightly more than $3,000.00.
The NRM-lMJ screen, as a feather screen, -will handle feathers from about
8,000 birds per hour.
The NHJ4-lii8 screen, as an offal screen, will handle the viscera from
about 10,000 birds per hour.
We will now discuss the proper feeding to the screen and the maintenance
required on the screen.
The influent to the pretreatment screen has had most of the feathers and
viscera removed and the screen1s primary function is to remove most of the
remaining solids from the plant wastewater before it goes to the sewage treat-
ment plant. The ideal way to feed a vibrating screen is directly by gravity
from the flowaway system. The velocity of the water must be fed over the
screen so as to reduce screen blinding* The screen is installed at a 10 degree
down slope and as the pretreatment screen is subjected to wastewater with a
high fat content, the less pumping that is done, the longer the screen cloth
operates without blindingo Pumping breaks down fat in the water and the
smaller particles cause blinding. Emulsified fats from cooking can also have
the same effect. In some plants where a high percentage of the fats are
emulsified, the screen cloths must be sprayed intermittently with hot water
or steam to remove the fat or an automatic spray system should be installed.
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Good efficiency in feather removal is reported. In fact, a plant engineer
at a poultry plant in Athens, Georgia states that a U x 8 vibrating screen
operating as a pretreatment screen, showed only one feather in the effluent
in a 2U-hour test.
The normal maintenance on a liquid dewatering screen consists of greasing
the bearings at regular intervals, and maintaining the proper spring tension
on the screen cloth. If you experience screen cloth breakage and the break
is parallel to the longitudinal members of the screen deck, you can be assured
the screen broke because it was too loose.
The operating cost of an NRM-1U8 liquid dewatering screen is the current
required to operate a 2-HP motor.
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liquid vibrating screens
39J888
0)
4598?
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II C. Static Stationary Snr«Mii H. £• Qiappsm
During the past two or three 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 pack-
ing, tanning, canning, textile, and paper and board products industries,
as well as in domestic sewage treatment operations. Interesting new develop-
ments 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 other cases, stationary screens are installed
as replacements for screens that require moving parts to make a suitable
separation of solids front a process stream.'
Basic Design concepts:
The primary function of a static screen 1s to remove "free" or surface fluids.
This can be accomplished by several ways, and in older concepts, only
gravity drainage is Involved. A curved screen design using high velocity
feeding was developed and patented in Europe 1n the 1950's for mineral
classification has been adapted to other uses in the process industries.
This design employs an interference to the flow which knifes off thin layers
of the flow over the curved surface.
In 1969, U.S.A. and foreign patents were allowed on a 3-slope static screen
made of specially coined curved wires. This concept uses 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 fiberous suspended matter.
Since the field tests to be reported were conducted on the later design of
stationary screen, details of this unit are herein presented. The device
is known commercially as a Hydrasieve.
Method of Operation:
The slurry to be screened or thickened, is pumped or may flow by gravity
into the head box of the machine. As shown in Figure 1, the incoming fluid
overflows the weir above the screen area and is accelerated in velocity
and thinned 1n depth as it approaches the screen. A lightweight hinged
baffle is incorporated Into the assembly 1n such a position that it reduces
any turbulence 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.
Suspended solids tend to stratify in the thin stream, and fibrous materials
align themselves with the direction of flow. Figure 2 shows a segme"ntal
section of the screen wires and the slurry as it contacts the upper end of
the Hydrasieve screen. Mote that the wall attachment bends an under portion
of the flow, a portion of the underflow also moves along the arc surfaces
of the wires and is primarily concentrated at the apex of the arc. Here it
-------
-2-
falls from the screen back or flows in streams attached to the underside
of the wire assembly in a direct path between the supports. The screen
pattern permits a maximum of fluid extraction based on the limit of time
and screen area.
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 displacement
with oncoming material.
HOW IT WORKS
Gravity feed
of liquids/solids
Self cleaning,
non clogging stainless
steel screen for
continuous dewatering
Rugged all stainless
steel or fiber
glass construction
minimizes maintenance
Headbox
Alternate
feed inlet
Removed or
recovered
solids
"Cleaned" effluent improves plant
pollution control efficiency,
lowers B.O.D., reduces sewage rates
Solids
Note how "Coanda" effect strips liquid from
bottom of the stream flowing down the
screen. This "wall attachment" effect
accelerttes fluid removal action.
Downward curve of MHNV screen bars
divides the flow of slurry into separate
streams between the vertical supports thus
preventing clogging or blinding.
Figure 3 shows a typical completed assembly of the screen installed in
an Ohio poultry processing plant, and Figure 4 illustrates the design of
the special screen employed in the test work.
-------
-3
-3-
Unique featuresr
The arrangement of transverse vires with unique singular curves in the sense
of flow provides a relatively non-clogging surface for dewatering or screen-
ing e The screens are precisely made in No. 316 stainless steel and are ex-
tremely rugged. Harder, wear-resisting stainless alloys may also be used
for special purposes.
Openings of 00010 to 0.060 inches meet normal screening needs* The essential
features of the Hydrasieve are covered in U.S. Letters Patents No. 3,1452,876
and No. 3,751,555. Other U.S. patents are pending. Patents are also issued
and pending in foreign countries.
Advantages. The wedge bar screen has a number of advantages over vibrating and
rotary screens, including:
1. Low initial cost.
2. Compact and inexpensive to install.
3. No motor, no wires, no moving parts, no noise.
U. Requires little, if any, attention.
5. Stainless steel construction. Fiberglass frame optional.
6. Screens will not puncture or warp.
7. Wide variation in flow rate or loading does not seriously affect per-
formance.
8. Uniform terminal solids moisture can be maintained.
'9. Units can be readily combined with secondary and tertiary biological
treatment systems.
10. Assemblies of units are readily constructed to meet high capacity flow
needs.
Summary»
Wiile the screening device described is now widely accepted for solids
removal from effluents in many process plants, it is not yet commercially
established in the poultry industry, primarily due to the manufacturer's
unfamiliarity with its operations and problems. However, the exploratory
work due within the next sixty days Indicates that improvements in
effluent quality can be made along with some economic advantages.
-------
TYPICAL DESIGN INFORMiTIQH FOR CHICKEN PROCESSING PLANT EFFLUENT
BASED (M USE OF .020 INCH SLOT OPENING
HYDRAS IEVE
Mo.
No.
Mo.
Ho.
No,
Mo.
Mo.
No.
No.
No.
552-18"
552-36"
552-48**
552-60"
652-72"
S62-72-2
552-72-0
552-72-6
552-72-8
552-72-10
OVEMLL DIMENSIONS - FEET
HIPTH UEPTH HEIGJJff
2 S.5 5
3.5 4 5
4.5 5 7
5.5 5 7
6.5 5 7
7 9.5 7.3
14 9.5 7.3
21 9.5 7.3
28 9.5 7.3
35 9.5 7.3
WEIGHT
POUBPS
350
ISO
650
800
1000
1800
8600
S400
7200
9000
CAPACITY
6.P.N.
25
SO
125
175
223
050
100
1350
1800
2250
PRICE FOR ESTIMATING
$ 2.600
$ 3.200
$ 4.000
$ 5.000
$ 6,300
$10.000
$20.000
$30.000
$40,000
$50,000
-------
TLO-I
D, Other Screening Devicesi &. J. Steffen
1. Rotary screen (Revolving, Trommel, Scrubber or Barrel Screens).
Rotary and Titrating screens are the most popular types in
poultry wastewater processing.
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 affluent sewer mounted
below the screen. The screen is usually sprayed continuously ty
means of a line of external spray nozzles. The screen is usuaJly
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
screening.
The other sost common type and one used to some extent in
secondary screening is driven by an external pinion gear. The in-
fluent is discharged into the interior of the screen below center,
and solids are removed in a trough and screen conveyor mounted
lengthwise at the canter line of the barrel (see Figure nB" and
section view "C"). The liquid exits outward through the screen
into a box in which the screen is partially submerged. Perforated
lift paddles mounted lengthwise on the inside surface of the screen
assist in lifting the solids to the conveyor trough. This type is
also generally sprayed externally to reduce blinding. Four of
these screens (51 dia. x. 12' long with 10 x 10 mesh-cloth) were
installed at the municipal sewage treatment plant in Girt neuvilto,
Georgiai in 1961 to polish the raw waatewaitar. They oporutu ul
it r.p.m. and each treats 2 million gallons per day. At thut t1 m«i
-------
cut
mm
MCMrn* *tuw q/fmdtf
Aortntfjr*
tfrv&urv/ fOtf
jrtvng t**ar>
/vctmig font
Of
tOHUM tnowm COWJTRUCTKW •
-------
HO-
there were 7 poultry processing plants in Gainesville and the
central system solved maintenance and operating problems at the
municipal plant, resulting from residual feathers and offal which
were not captured by offal and feather screens at the processing
plants.
2. Other Mechanical Screens.
Several other types of mechanical screens have had limited
application in this field.
One is a rotating disc which is partially submerged in the
wastewater flow. As it rotates, particles partially adhere and
are scalped off above the flow. The screen disc is placed verti-
cally or at a slight angle.
Another type is a circular spring-mounted horiaontal 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 centrally fed at the top, with liquid
discharging through the screen to a pan above the motor and sludge
discharging fron a port at the periphery (see sketch "D"). Small
units (18* dia.) are available on loan for testing.
There are many other ingenious mechanical screens but they
have not been tested on poultry wastewaters. Some, such as a
vertical spinning drum, have successfully screened red meat waste
solids. With the impetus of need to improve effluents, testing
such devices on poultry waste may be accelerated.
-------
- TREATMENT OF POULTRY PROCESSING WASTE
BY DISSOLVED AIR FLOTATION
Charles B. Grimes
Sales Engineer - Industrial Haste Treatment Products
Process Equipment Division
Environmental Control Group
REX CHAINBELT INC.
Dissolved air flotation 1s a waste treatment process In which
oil, grease and other suspended matter 1s 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 applica-
tion of this treatment system has been the removal of contaminants
from the food processing plants waste streams. One of the very
first applications of this treatment system was for this purpose.
Basically, dissolved air flotation 1s a process for removing
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 1n 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 verticil rate of rise noted as VT.
Figure No. 2 Illustrates the basic design considerations of the
flotation unit. The parameter, VT was dlscusttd above and tho measure
merit of this parameter will bt dlscuitfd later, blnce the waste
-------
Treatment of Poultry Processing Waste
By Dissolved A1r Flotation tt£ & -2.
flow must pass through a treatment unit, the particle 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 1s 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
valve.
A 40-psig pressure drop occurs at the pressure reduction
valve and causes the pressurized flow stream to relinquish it 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 recycle flow containing
the air bubbles) Is mixed and uniformly distributed over the cross-
section of the basin.
-------
Treatment of Poultry Processing Haste
By Dissolved Air Flotation HI B -3
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. From the effluent wet well, a portion of the effluent
1s recirculated. 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
pressurization, as the name Implies, Is where the total waste flow
1s pressurized prior to entering the treatment unit. Partial
pressurization 1s 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 uio of chemical conditioning 1s normally
associated with a high degree of emulslfIcatlon of the oil or grease
matter 1n waste stream flow. It 1s, therefore, a requirement to
break the emulsion and form a floe to absorb the oil or grease. It
-------
Treatment of Poultry Processing Waste
By Dissolved Air Flotation
has been shown (Figure No. 5) that by Increasing the particle
size, the rate of separation is Increased. Flocculation as a
means of promoting particle growth preceding flotation contributes
to the effectiveness of the flotation process where chemical
conditioning is used. The points of chemical Injection and the
possible use of flocculation 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 poultry processing industry. This
arrangement provides an economical, flexible design which requires
minimal construction cost and area Investment (Figure No. 7).
Most manufacturers of dissolved air flotation units have complete
line of steel tank units to meet a wide variety of flow conditions.
Figure No. 8 shows a partial listing of steel package units manu-
factured by Rex Chainbelt. The Model No. 9550A shown would handle
a raw waste flow of approximately 800 GPM, the Model No. 8032
handles a raw flow of about 300 GPM, and the Model No. 6020 would
handle a raw flow of about 200 GPM. 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 flocculation as a part
of chemical pretreatment. Figure No. 9 illustrates this arrangement
This particular unit includes two stages of flash mixing preceding
flocculation and flotation and 1s shown Just prior to shipment. The
access ladders, handrails and drive units will be removed before
-------
Treatment of Poultry Processing Waste
By Dissolved Air Flotation Jj| 0» -5"
shipment. From this Illustration, it can be seen that a minimum
of field Installation work 1s required since the unit has been shop
assembled.
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 central
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/KWH.
Chart II illustrates typical results from the treatment of
poultry processing wastes by dissolved air flotation with and without
chemical treatment. The raw waste characteristics and treatment
results shown in Chart II are for grab samples from a unit in
-------
Treatment of Poultry Processing Waste irr A
By Dissolved Air Flotation ttl O -
Alabama. The characteristics of this waste are somewhat stronger
than the waste normally encountered In this application, and, therefore,
the necessity of chemical treatment 1s evident for this particular
application. The raw flow to this unit 1s 150 GPM and based upon a
lime dosage of 100 mg/1, the total lime usage in a single 10 hour
working day would be 76 pounds. Extending this usage to a continuous
operation of 5 days per week, 52 weeks per year, the yearly lime
usage would be approximately 20,000 pounds per year. The cost of
this amount of lime would be about $1,000.00 per year and capital
cost of simple lime feed system would be between $6,000.00 and $8,000.00
As 1s the case with most industrial waste, treatabllUy studies
should be conducted to determine not only the design parameters
for a flotation unit, but also to determine if chemical treatment is
a necessity to meet treatment objectives.
Pilot dissolved air flotation units (Figure No. 10) are available
from most manufacturers for treatabllUy studies. The rental cost
varies, but the normal rate 1s 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.
This flotation test (Figure Nos. 11 and 12) 1s used to determine
the suspended particle rise rate (VT) which 1s 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
redrculatlpn of the unit effluent of pressurlzatlon In a full size
-------
Treatment of Poultry Processing Waste
By Dissolved Air Flotation US-7
unit; this 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 1s put Into the solution. The
pressurized liquid 1s 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 1n the selection of the
basin size necessary to accomplish treatment required.
-------
me>- e
i
-------
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-------
FIGUKt 3
CP
I
-------
PUMP
TOTAL TANK
3. PAKTIAL
e
a
-------
FIGUK 5
0.50
UJ
0.40
u.8
o v
fc!~ 0.30
0.20
0.10
p/
x**c
EFFE
ARTICLE
lOOppm 1
i
c
>
:CT OF ^
SIZE 0
.ime- 20 1
20% Rec
BBBB
_^t
)*"x"
WERAGE
N RATE
ppm Bento
ycle
X
OF RISE
nite
f
^^ \.
)xX
^
^
0.40 0.50 0.60 0.70
AVERAGE PARTICLE SIZE
(mm)
0.80
-------
OILY
SC
WASTE
FLOCCULATING
AGENT ,
(IF REQUIRED)
CLARIFIED
EFFLUENT
WASTE
FLOCCULATING
UP REQUIRED)
TOTAL
OILY SCUM
FLOCCULATION
CHAMBER
(IF REQUIRED)
FLOTATION
CHAMBER
AIR
CLARIFIED
EFFLUENT
PRESSURE
RETENTION
TANK
PAOTIAL
OILY
SCUM
FLOCCULATING
AGENT k
(IF REQUIRED)
FLOCCU-
LATION
C HAWSER
(if RIQ'D)
FLOTATION
CHAMBER
RETENTION
TANK
AIR
CLARIFIED
EFFLUENT
PUMP
FIGU/X G
-------
-------
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161-185 30
186-210 30
211- 25C 30
251-275 36
276-310 36
311-360 42
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41-455 42
456-M5 42
506-550 42
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320-499 ^
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-------
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CHAPTl
OPERATING
MODEL
I. FLASH M/xeB —
2. FLOCCULATOR— ft
3. SKIMMCS ..... ft
4. BOTTOM 6cecw-~ '/e
5. ffeevcLc RJMP - 71/*
G. CQMPRCSSO0 I'/t
11.0
ON IOHG/OAY, SQAV/wreiC OpeBAT
-------
JIB-16
CHART E
PCSULTS
I. &AW M/Asre
a. 6OO6 * Z46O mq/t
b. S. S. • &<* mg/l
c. OIL 4 0aeAse • too
2.
ybfflfCYCtf CHfMICAL*
A/o. £0 S.S.
/ 33 none 3t> £4
2 SO none 39 V2
3 33 lOOmg/i.lime 57 61
4 33 300 erq/l . O/um 33 94
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*«•«
10
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!NT PARTS - HKX PIOT-AJIj", K T
IFIKD '•"FFL'rsNT IN FLOT-.MRE i'.JvV.
iff*' ^''"^ P^ss™!2^ TO ^° p«i«
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uz a -
A :•: !•(;•<
-IGURt 12
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urc-i
III C. Other Systems; A,. J. Steffen
Whereas the preceding section (B) was limited to a discussion of
rectangular dissolved air flotation systems, it should be noted that
the same principle is 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 as
those used in rectangular tank systems. The accompanying flow diagrams
show typical poultry plant pretreatoant systems incorporating circular
flotation tanks* One is a small plant in Allentown, Pa., and the other,
using two flotation tanks in parallel, is at a large poultry plant in
New Holland, Pa. The data shown for the New Holland operation was de-
veloped in preliminary tests and is reported to be typical of current
operating results, using chemical treatment (a polymer) to enhance
clumping or agglomerating of the fine suspended and colloidal matter,
thereby improving flotation. The costs shown include the flotation
tanks complete with pumps, air saturation tanks, and mixing tanks and
mixers but do not include the screens nor the cost of erection.
In some cases, vacuators have been used to separate floatables in
pretreating poultry plant wastewaters* Vacuators are basically complete-
ly enclosed concrete tanks where a vacuum is applied as the wastewater
passes through the tank. The vacuum enhances flotation in a 3-produot
separation similar to air-pressurised flotation* The need for complete
enclosure limits observation of operating characteristics. Designs range
from 300 gpn to 2000 gpm per unit. As stated in II D, a vacuator in-
stalled in Arkansas to treat 1,2£0,000 gallons daily cost $lif?,000 in 1969.
-------
nrc-z.
JAINDL'S TURKEY FARM
ALLENTOWN. PA.
100,000 GPD
RAW WASTE
SCREEN
APPROXIMATE EQUIPMENT
COST - $t3O,000
LIME
ALUM
POLYMER
1250 GAL
MIX TANK
15-0"
DIAMETER
SEDIFLOTOR-
CLARIFIER
100 GPM
PRESSURIZED
RECYCLE
EFFLUENT TO
AERATED LAGOON
Wesnnghouse Electric Corporation
Inlilco Division Box 2118 Richmond, Va 23216
Puranlin USA
-------
VICTOR F. WEAVER
NEW HOLLAND, PA.
21006PM
RAW WASTE
LIME
POLYMER
FES04
APPROXIMATE EQUIPMENT
COST -$65,000
1050 6PM MAX
25-0
DIAMETER
SEDIFLOTOR
CLARIFIER
25-0
DIAMETER
SEDIFLOTOR
CLARIFIER
1050 GPM
MAX RECYCLE
AIR
T
1050 GPM
MAX
RECYCLE
EFFLUENT TO
CITY SEWER
PRELIMINARY TEST DATA;
RAW WASTE
EFFLUENT
%REMOVAL
COD
MG/L
2815
334
68
BODg
MG/L
1350
213
84
TSS
MG/L
1034
43
96
P04
MG/L
54.5
2 4
96
GREASE
MG/L
623
8
99
CHEMICAL
10 MG/L
C-31
Westinghouse Electric Corporation
Infllco Division Box 2118 Richmond. Va 23216
Nntnil In LISA
-------
m-i
IV. SUMUAEIt A. J. Steffen
Pretreataeat of poultry processing waeteirater, prior to discharge
to a Bonicipal system, is a consideratioai
1. Ihen constituents prohibited by municipal regulations are
present in the wastewater. Feathers, whole blood and entrails
are typical of such prohibited Materials.
2. When »»•*<••• concentrations hare been established for certain
constituents and the wastawator contains such constituents in
excess of those limits* BOO, grease and oils, and suspended
solids are examples of such constituents.
3. When the poultry processor is paying or anticipates paying for
municipal treatment through a surcharge system and can effect
economies by pretreatment. Examples of constituents for which
surcharge rates may be established are: BOD, suspended solids,
and possibly grease and oils.
Decisions regarding the last item are the most difficult. To save
"surcharge11 dollars by pretreataent, the'poultry plant operator must
determine the degree of pro-treatment that represents the economic break-
point. He must also weigh other factors such as the probability that the
surcharge rates may change, that the municipal treatment plant may need
expansion in the near future and may seek a Federal grant which will intro-
duce requirements previously discussed, and that the state may establish
regulations relating to pretreatment both as to degree of treatment and
operation of the facilities (such a law was recently passed in Mew Jersey).
The processor must also consider his own future business plans, such as
changes in processing, additional processing, overall expansion, or possibly
reduction in operations.
-------
TS-2.
Within these often elusive variables, the poultry processor must
select the type of pretreatment, such as:
1. No pretreatment at all.
2e Secondary screening only.
3. Secondary screening and separation of floatable and settleable
solids by gravity, pressurized air flotation or other means.
U. Separation of floatable and settleable solids, as in 3 above,
but without secondary screening.
5. Treatment as in 3 above plus biological or chemical treatment
for further BCD removal.
The pretreatment processes and the capacities selected depend upon
the size of the processing plant, efficiency of the selected process,
facilities for handling the materials removed from the irastewater, and
related engineering and cost factors, as well as the three regulatory
considerations set forth above.
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