United States
Environmental Protection
Agency
Industrial Environmental
Research Laboratory
Cincinnati OH 45268
EPA-600/2-78-039
March 1978
&EPA
Research and Development
Recycling of Water
in Poultry Processing Plants
Environmental Protection
Technology Series
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal spe-
cies, and materials. Problems are assessed for their long- and short-term influ-
ences. Investigations include formation, transport, and pathway studies to deter-
mine the fate of pollutants and their effects. This work provides the technical basis
for setting standards to minimize undesirable changes in living organisms in the
aquatic, terrestrial, and atmospheric environments.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-78-039
March 1978
RECYCLING OF WATER IN POULTRY PROCESSING PLANTS
Interim Technical Report
by
C. J. Rogers
Stanford Research Institute
Menlo Park, California
Contract No. S-800930
Project Officer
Jack L. Witherow
Food and Wood Products Branch
Industrial Environmental Research Laboratory-Cincinnati
Corvallis, Oregon 97330
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Industrial Environmental
Research Laboratory-Cincinnati, U.S. Environmental Protection
Agency, and approved for publication. Approval does not signify
that the contents necessarily reflect the views and policies of
the U.S. Environmental Protection Agency, nor does mention of
trade names or commercial products constitute endorsement or re-
commendation for use.
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FOREWORD
When energy and material resources are extracted, processed, converted,
and used, the related pollutional impacts on our environment and even on our
health often require that new and increasingly more efficient pollution con-
trol methods be used. The Industrial Environmental Research Laboratory -
Cincinnati (IERL-CI) assists in developing and demonstrating new and improved
methodologies that will meet these needs both efficiently and economically.
"Recycling of Water in Poultry Processing Plants" presents the results
of pilot scale studies on treating water for recycle in the chiller used in
poultry processing. Several combinations of treatment processes were evalu-
ated. The use of a diatomaceous earth filter was the most economic option
that maintained bacterial levels below that in a chiller without recycled
water which was the project control. This interim report completes EPA work
on this project although all planned activities were not completed. For
further information contact Dr. H. Kirk Willard, Food and Wood Products
Branch, Industrial Pollution Control Division, lERL-Ci.
David 6. Stephan
Di rector
Industrial Environmental Research Laboratory
Cincinnati
iii
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ABSTRACT
Studies were conducted on recycling chiller water in a poultry process-
ing plant. The USDA requires a half gallon of water per bird in the chiller
system to ensure sanitary product quality. In order to maintain equivalent
chiller water quality at reduced flow a recycling system must be provided
with the capability of removing solids and controlling the microbial popula-
tion.
UV was used to control the microbial population. For this control to
be effective, solids must be removed to a level to allow light transmission.
Methods studied include: 1) cyclonic desludgers, 2) vibrating screens,
3) floatation cells, 4) centrifugal waste concentration, 5) filtration with
diatomaceous earth (DE) filter aid, and 6) activated carbon.
Water from a pilot-scale chiller was passed through a pilot diatomaceous
earth filter system having an equivalent pore size of 0.7u and returned to
the chiller for reuse. At 60 percent recycle, water in the chiller using
the recycled water maintained a bacterial level equivalent to that in a com-
parable nonrecycle system. The recycle and reuse of chiller water can re-
duce new water requirements per bird from 0.5 gallons to 0.2 gallons with-
out a deterioration in the bacterial quality of the water in the chiller.
Operating costs for the DE filtration system with 30 gallons (113.5 1)
equivalence of ice per minute are $79.06 per day. Normal operating costs of
the chiller without recycle are $146.90 per day, thus a savings of $67.84
per day. These do not include manpower and equipment costs. Figures are
calculated based on a system that overflowed 100 gpm (6.31 I/sec) for an
18 hour day.
iv
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Section Page
I. Introduction 1
II. Experimental Procedures 3
III. Summary 20
.>
IV. Appendix 28
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TABLES
Number Page
1. Characteristics of Prechiller Water 5
2. Chill Tank Benchmark Data for Chilling System 6
Processing 200,000 Birds Per Day
3. Characteristics of Chill Water Treated With A 7
Cyclonic Desludger
4. Characteristics of Chilled Water Passing Through 7
a Vibrating Screen
5. Characteristics of Chill Water After Treatment 9
With Centrifugal Waste Separator and Floatation
Cell
6. Characteristics of Prechiller Water After Treatment 9
With Diatomaceous Earth Filter
7. Characteristics of Prechiller Water After Treatment 11
With Diatomacebus Earth Filter, Activated Carbon,
and Ultraviolet Light
8. Optical Density of Prechiller Water After Treatment 15
With DE Filter, Activated Carbon, and UV Light
9. Bacteriological Results of Pilot System Without 19
Activated Carbon
10. Bacteriological Results of Pilot System Without 19
Activated Carbon or Ultraviolet Light
11. Total Solids and Total Bacterial Count Comparisons 21
of Three Water Recycling Systems Versus Conventional
System Used In Chilling Poultry
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FIGURES
Number 'Page
1. Poultry Chill Water Treatment 12
2. Pilot Test System for Recycling Poultry 14
Chilling Water
3. Ultraviolet Energy Versus Time in Pilot 16
Recycling System Using Activated Carbon
4. A Pilot Recycling System Without Activated 18
Carbon
5. A Pilot Recycling System Without Activated 18
Carbon or Ultraviolet Light
6. Rough Schematic Diagram of Proposed Diatomaoeous 22
Earth Filter System
Vi i
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SECTION I
INTRDDUCTICN
By federal regulation, exceptionally large amounts of water most be used
in the processing of poultry. At several processing steps, specified quanti-
ties of water must be used per bird. The primary objective of this water use
is to ensure a sanitary product, particularly from a microbiological stand-
point. A major need exists not only to decrease the quantity of water used,
but also to decrease the concentration of contaminants—primarily organics—
in the water as it leaves the plant.
In a research program being sponsored by the Environmental Protection
Agency and the Pacific Egg and Poultry Association, Stanford Research Insti-
tute is performing studies that, it is hoped, will lead to essentially a com-
plete recycling of water in the poultry processing plant. This study is to .
demonstrate the efficacy of the recycling concept by establishing a full-
scale recycling system in the chiller operation of a poultry plant. The chill-
er operation is essentially the last step in the processing of the bird, and
its function is to reduce the body temperature of the bird from 98°F to 34-
35 F*. In most U.S. processing plants, this operation consists of flowing the
birds through tanks of chilled water. To prevent an excessive build-up of
contaminants in the tanks, the processor is required to have an overflow of
one half-gallon of water per bird from the chill tank, with the make-up being
provided by potable water.
In the poultry processing plant where this study is being performed,
approximately 200,000 birds are processed each day; processing time is 16 hours
per day. With the overflow requirement and the initial volume of the tanks,
approximately 125,000 gallons of water are used per day in the chiller system.
If a complete recycling system could be used, the following specific im-
provements would be achieved:
(1) A saving in water consumption.
(2) A decrease in the amount of waste effluent from the chiller.
(3) A saving in the refrigeration costs.
(4) A change in the USDA's requirement of a half-gallon of overflow
per bird.
(5) Technology that could be used at additional locations in the
poultry processing plant and in other food industries.
Considerations of the impact of a recycling system are described in the
* For metric conversions, refer to the appendix.
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experimental section of this report.
To accomplish the goals of this study, it is necessary to have a
recycling system that will remove a large portion of the solids in
the water and will provide a means of keeping the microbial popula-
tion down. Such a system is described in the experimental section.
This report covers the water recycling program in the poultry
processing plant from the inception of the program (June 12, 1972)
to the present. At this point, sufficient data are available to
allow for the scale-up of the entire system.
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SECTION II
EXPERIMENTAL PROCEDURES
STUDY SITE AND CHARACTERIZATION OF PLANT
The recycling portion of this study is being performed at Foster Farms in
Livingston, California, and the analytical work is being conducted at Stanford
Research Institute, Manlo Park, California. Foster Farms processes approxi-
mately 190,000 birds per day in two eight-hour shifts; two parallel processing
lines are used, each handling 95,000 birds. This method provides an ideal
situation for this study because a recycling system can be applied to one line,
while the second line serves as a control.
The last step in the processing of the bird before it is graded and pack-
ed is to chill the bird to approximately 35 F by immersing it in chilled water.
The system consists of a prechill tank containing approximately 1,500 gallons
of water at 48 F and a final chill tank containing 7,000 gallons of water at
32 F to 33 F. At the present flew rate, each parallel chill system receives
100 birds per minute, reguiring 50 gallons per minute (gpm) of overflow. The
potable make-up water is added to the chill tank in the form of chilled water
(35 gpm at 33T1) and ice (15 gpm). Fifty gpm flows from the prechiller into
the general effluent of the plant* At this overflow rate, a turnover in the
volume of the chill system takes 140 minutes.
To provide for a cleaner system, the water in the prechill tank is
changed twice, in addition to the original fill. Therefore, as a result of
the original filling of the chill system, the overflow, and the changing of
the prechiller, a total of 59,000 gallons of water is used for each of the
parallel chill systems, giving a total of 118,000 gallons per day.
ANALYTICAL STUDIES
The following analyses are performed on the water samples:
. BOD
. Total solids
. Total fixed residue
. Nonfilterable residue
. Nonfilterable fixed residue
. Filterable residue
. Filterable fixed residue
. Oil and grease
. Iron—filterable
. Chlorides
. Total plate count
. Total coliform
. pH
. Temperature at time of sampling
. Absorbancy at 253.7 nm
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In general, the methodology of the American Public Health Association
(Standard Methods for the Examination of Water and Wastewater, 13th ed.,
APHA, New York, 1971) is used for the analyses.
CHARACTERISTICS OF THE CHILL SYSTEMS WATER
Table 1 shows characteristics of the water from a prechiller tank.
The table shows the high and low values that have been observed in our
analyses as well as the average from all analyses and the number of
analyses run to determine the average. The characteristics of the
water coming into the plant are also described. The optical density data
are of significance, since a component of the recycling system is the
ultraviolet light of 253.7 nm, which kills microorganisms. For the sys-
tem to function properly, a good transmission through the water must be
achieved. As seen in Table 1, the original prechill water has less than
2% transmission. A diatomaceous earth filter to remove suspended
solids (nonfilterable residue) and activated carbon to remove some dis-
solved solids (filterable residue) are used in the recycling system to
increase the ultraviolet transmission.
Table 2 presents data on the characteristics of the average ma-
terials that are washed from the birds in the chill system and gives
the totals for a 200,000-bird operation such as the one at Foster Farms.
STUDIES ON THE KEMDVAL OF SOLIDS FROM THE WATER
Since the primary requirement of the recycling system is that it
maintain a sanitary condition in the chill system, the water must be
treated to decrease the microbiological content. In the system used in
our early studies, UV light was used to accomplish this goal. However,
sufficient solids (both solub3.e and insoluble) must be removed to get
adequate transmission of the UV light in the sterilizing chambers. Vari-
ous systems have been examined to determine the most suitable means of
removing the solids. These are described below.
Cyclonic Desludgers
The original proposal for this study indicated that cyclonic de-
sludgers (SS-500, Ultradynamics Corporation) would be used to remove
the suspended solids (nonfilterable residue). One of these units was
received in October 1972, and tests were begun to determine its effec-
tiveness in removing solids to allow increased UV transmission. As
the results presented in Table 3 show, these cyclonic desludgers are
inadequate for removing the types of suspended solids present in poul-
try chill water. Since cyclonic desludgers operate primarily on dif-
ferences between the density of the suspended solids and that of the
water, this result—in hindsight—is not surprising.
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TABLE 1. CHARACTERISTICS OF PRECHILLER WATER
Materials Present
in Water
BOD (mg/1)
Total solids (mg/l)
Nonfilterable residue
(rag/1 )
Filterable residue
(me/i )
Oil and grease (mg/1 )
Total bacteria count
\cel Is/ml)
Coliform (cells/ml)
Optical density *
@ 253.7 nm
('p transmission)
Prechiller Water
High
750
1561
660
370
1.3 X 106
2.4
( 1*)
Low
304
762
123
73
6.08-X 102
0.88
(13*)
Average*
502/25
1081/29
272/28
8O9/28
138/24
3.3 X 105/6
6.0 X 103/2
1.7/2
(2%)
Incoming
'Water
0
254
4
250
—
—
__
0.036
(93$)
* Calculated average/no, samples tested
+ 100* = distilled water
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TABLE 2. CHILL TANK BENCHMARK DATA FOR CHILLING SYSTEM
PROCESSING 200,000 BIRDS PER DAY
Materials Washed
from Bird
BOD
Total solids
Nonfilterable
residue
Filterable
residue
Grease
Average
(mg/1 )
502
1,081
272
809
138
Water
Supply
(mg/1)
0
254
4
250
0
Differ-
ence
(mg/1)
502
827
268
559
138
mg/bird
973
1,602
519
1,083
267
Ib/day
429
706
229
477
118
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TABLE 3. aiARACTERISTICS OF CHILL WATER TREATED
WITH A CYCLONIC DESLUDGER
Materials Present in
Water
HOD (mg/ml)
Total solids (ing/ml)
Noni'il terable residue (mg/ml)
Oil and grease (mg/ml)
Total bacteria (cells/ml)
Optical density © 253.7 nm
(% transmission)
Chill Water
(Initial)
825
943
251
73
6.2 x 10'1
1.3
(5?o)
Water from
Desludger
720
834
114
7-1
1.06 x 105
1.6
(2%)
TABLE 4. CHARACTERISTICS 0? CHILLED WATER PASSING
THROUGH A VIBRATING SCREEN
Mnfpririls Present in Water
Total solids (m^/mi)
iNonfil terablc residue (mg/ml)
Oil and grea.se (mg.ml)
Optical density
('i' 253.7 nm
Chill water
1146
272
135
1.5
Water from Screen (size*)
.
84/170
950
270
93
1.3
165/90
810
157
47
1.3
230/63
893
152
60
1.3
400/37
823
107
31
1.3
* Si/e - mush/si?.e of openings
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Vibrating Screens
Vibrating screens with various pore sizes were examined next. These
screens were not intended to be alone in the removal of solids, but they could
be used for removing most of the larger suspended solids. As Table 4 shows,
the screens did remove a portion of the suspended solids, but not a significant
amount.
Flotation Cells
Since many of the suspended solids in the chill water are fatty or pro-
teinaceous in nature, flotation systems should be successful in removing a cer-
tain percentage of the suspended solids. Table 5 shows data on the effective-
ness of a flotation cell. The system is generally described In the following
section.
Centrifugal Waste Concentration
One of the primary drawbacks in the use of a screening system for the re-
moval of solids is that, if a small enough mesh is used to remove a significant
quantity of small solids, the flow of water is highly restricted. However,
several systems are commercially available in which the water is forced through
the screen by a centrifugal action, while the solids are sloughed off by vari-
ous techniques, such as a high-pressure backwash. Such a system, capable of
flow rates up to 300 gpm, was made available to us by Sweco, Inc. In addition
to removing suspended solids by the screen, the water passing through this sy-
stem was aerated, making it well suited for removal of solids in a flotation
cell. Table 5 shows data collected for such a centrifugal screeening system
combined with a flotation cell. In this particular study, flow rates of 80 gpm
were used.
As the results in this table show, 58% of the suspended solids (nonfilter-
able residue) were removed. However, this is not sufficient for obtaining ade-
quate UV transmission. Furthermore, up to 20% of the total water flow ended
up with the sludge.
Filtration with Diatomaceous Earth Filter Aid
Filtration systems obviously offer the greatest potential for removing
suspended solids down to the smallest size with the most ease. However, for
removal of large quantities of material while maintaining high flow rates,
filter aids must be used, such as diatomaceous earth (DE). Not only can ex-
ceptionally fine equivalent pore sizes be obtained with (DE), but, by con-
tinually adding DE body feed during the operation of the filter, clogging can
be avoided.
Table 6 shows data for the water after it has passed through a DE filter.
Data are presented for the existing prechiller water, the filtered prechill
water, and a model prechiller in which the water has
8
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TABLE 5. CHARACTERISTICS OF CHILL WATER AFTER TREATMENT WITH
CENTRIFUGAL WASTE SEPARATOR AND FLOTATION
Materials Present in Water
BOD
Total solids (m^/ml)
Nonf ilterable residue (m^/ml)
Oil and grease (m^/ml)
Optical density
«" 253.7 nm
Chill
Water
531
1147
295
187
1.93
Water from*
Centrifugal
Separation
438
958
124
61
1.38
Water from
Flotation
Cell
413
903
145
88
1.6
Sludge
from
Separation
798
2099
827
787
2.85
* Screen size = 37 p..
TABLE 6. CHARACTERISTICS OF PRECHILLER WATER AFTER TREATMENT
i
WITH DIATOMACEOUS EARTH FILTER*
Materials Present
in Water
BOD (nig/1)
Total solids +
(niK/1 )
Nonf ilterable residue
(raK/l)
Filterable residue *
(mg/1)
Oil and grease (mg/lj
Optical density
(253.7 nm) *
£.XlSt mt;
Prechiller
Water
623
1184/934
315
869/619
165
2.2
(
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been recycled. These data shew that the DE filter is able to remove
all suspended solids (nonfilterable residue), greatly reduce the BOD,
and remove a large portion of the oil and grease. Use of the filter
elevated the transmission of UV light from 1 to 16%. When the water in
the recycled predhiller is exchanged every 20 minutes with water from
the filter unit, the water is much cleaner than that contained in the
existing prechiller, which is turned over every 170 minutes.
Various types of DE filters were examined in this study. The
data presented in Table 6 were obtained while using a pressure leaf
filter with a precoat of 0.1 Ib of Hyflo Super Cel (Johns-Mainville) per
square foot of filter area. A body feed rate of 0.05% DE (weight/volume)
and a flow rate of one gallon per square foot of filter surface were
used.
Activated Carbon Studies
As seen from the data presented in Table 6, the DE filter was
able to remove essentially all of the suspended solids, thus increasing
the transmission of the UV light from 1 to 16%. This is not adequate
for efficient use of the UV lights, however. Therefore, it is neces-
sary to remove some of the dissolved solids that are interfering with
the UV transmission. In this particular system, the best means of do-
ing this appears to be with activated carbon.
Preliminary laboratory studies were conducted, and it was determined
that Darco S-51 activated carbon powder added with the DE body
feed at a level of 0.05% (W/V) was able to remove sufficient dissolved
solids (primarily organics) to increase the UV transmission to a satis-
factory level. Data presented in Table 7 shows that in such a system, the
UV transmission was increased from 2.4 to 65.6%.
MDDEL RECYCLING SYSTEM
To establish the overall efficiency of the proposed system, a pilot
model was established that was exactly equivalent to the present chill
system but was l/100th the size. This system had essentially all the
components shown in Figure 1; the figure shows a schematic diagram of
the system that has proved to be the most successful.
In our study, water is taken from the prechiller and chiller and
passed through a DE (equivalent pore size of 0.7 ^i) filtration unit to
remove the suspended solids. Water from the filter is passed through
an activated carbon unit, whose function is to absorb soluble material
interfering with the transmission of UV light. After leaving the carbon
unit, the material passes through a safety filter, whose sole function is
to guarantee that no carbon or DE can leak into the chiller system. At
this point, the water passes through an UV light system to kill micro-
organisms, through a heat exchanger for cooling, and then back into the
10
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TABLE 7. CHARACTERISTICS OF PRECHILLER WATER AFTER TREATMENT
WITH DIA1GMACEQUS EARTH FILTER, ACTIVATED CARBON, AND ULTRAVIOLET LIGHT
Materials Present in Water
BOD (mg/l)
Total solids (ing/l)
Nonlil terable residues (mg/1)
Filterable residues (mg/1)
Oil and grease (rog/1 )
Optical density
('253.7 nra)
Total bacteria count (cells/ml)
Reduction of bacteria (%)
Existing
Prechiller Water
347
1059
237
822
89
1.62
(2.4fo\
2.5 X 104
Treated Water
157
732
6
726
16
0.183
(65 - 6'%)
5.32 X 10°
99-9787o
11
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Figure 1. Poultry Chill Water treatment.
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chill tank.
Table 7 shows data an prechiller water after it has passed through
the DE filter, the activated carbon, and the UV light. Suspended solids
(nonfilterable residue) were removed, and some soluble solids (filter-
able residue) were removed, the latter allowing for an increase in UV
light transmission from 2.4 to 65.6%. Under these conditions, the
system decreased the bacterial concentration from 25,000 cells/ml to
5.32—nearly a four-log cycle decrease. It is also of interest that the
BOD was decreased from 347 mg/liter to 157 mg/liter.
Activated charcoal, to be feasible on a large scale, must be re-
generated instead of ^discarded. Regeneration consists of heating the
used material to around 400 F to burn off the absorbed materials.
This requires construction of a kiln capable of handling the amounts
of charcoal to be used daily, although charcoal is usually saved until
enough has accrued to make regeneration convenient.
Preliminary laboratory studies were conducted to determine:
(a) The amount of activated charcoal necessary
(b) The speed with which the charcoal would remove organics.
Water from the prechiller tank at Poster Farms was run into a
pilot chill system containing an activated charcoal train consisting
of three tubes 1 1/2 inches in diameter and 15 inches long, containing
0.5 Ib of Darco 4 X 12 activated charcoal each, as shown in Figure 2.
A precoat of 0.15 Ib of Hyflo Super-eel DE was applied to the filter,
and a body feed of 1 gpm was maintained. Foster Farms prechiller water
was allowed to enter the pilot chill tank at 0.2 qpm, and samples were taken
periodically from the pilot chill tank, the DE filter output, and the
output ends of each of the three carbon columns.
\
Table 8 shows optical density values of these samples after 4 hours
of operation. As can be seen, the carbon is reducing the optical density
in fairly direct relation to the amount of carbon present. The back pres-
sure built up across the carbon train was approximately 20 psi. Re-
ducing the particle size of the carbon would increase its efficiency,
but also increase its back pressure. Figure 3 shows that the carbon is
not removing absorbing compounds as fast as they are entering the system,
and the amount of disinfecting light falls below the required concentra-
tion after 4 hours of operation. Using more activated carbon would pos-
sibly cure this problem, but since this system is l/500th of the Foster
Farms chill tank system, the actual amount of carbon necessary would be
in excess of 7,500 Ibs of activated carbon daily. It was decided at
this point to investigate the possibility of using UV light of greater
intensity and omitting the activated carbon, or filtering out the bac-
teria with a finer grade DE.
13
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Foster Forms Water
•0.2 qpml
DE Body Feed
i
PILOT CHILL
TANK
0.5
!b
CHARCOAL
t
i '
DE MIXER
TANK
1 '
PUMP
Area -- 1.13 sq ft
1
FLOW
METER
i
I
DE FILTER
0.5 Ih
CHARCOAL
,
C3
0.5 Ib
CHARCOAL
1
uv
UNIT
Iuitradynamics No. 100
To Pilot
Chill Tank
NOTE:
, and C contain Da'co 4 K 12 activ^tfj charcoal.
Figure 2. Pilot test for recycling poultry dulling water.
14
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TABLE 8.
OPTICAL DENSITY OF PPSCHILLER WATER AFTER
WITH DE FILTER, ACTIVATED CARBON, AND UV
Sample Point
Pilot Chill Tank
After DE Filter
After C*
1
After Cn +
2
After C +
Optical Density
0,612
0.453
0.418
0.380
0.366
* Data taken after 4.0 hours operation,
+ Carbon columns.
15
-------
36
32
23
MOST MICRO-
ORGANISMS
DESTROYED
20
V)
O
MINIMUM U.S.
PUBLIC HEALTH STANDARD
MOST PATHOGENIC
ORGANISMS DESTROYED
456
TIME — hours
Figure 3. Ultraviolet energy versus time in pilot recycling system using
activated carbon.
16
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UV STUDIES
Since the activated carbon did not hold the absorbance down, it
was decided to try to filter out the bacteria using DE of a smaller
equivalent pore size; thus eliminating both the activated carbon and
the UV light. During these investigations, the UV light source was
increased in intensity.
A pilot chill system as shown in Figure 4 was assembled and sam-
ples taken periodically from the pilot chill tank, the DE output, and
the UV light output.
After the pilot chill tank had equilibrated (approximately 1.5 hrs.),
the bacteria counts (cells/ml) were averaged for each of the sample
points and are shown in Table 9. As can be seen, the DE removed 99.74%
of the bacteria and the UV light removed the remainder.
Based on the above results, it was decided that the added cost of
using the UV units overshadowed the benefit of removing the last 0.26%
of bacteria present.
STUDIES USING DE ALONE
Since the celite 512 appeared to be effectively reducing the bac-
terial count in the equilibrated pilot chill system with the UV light,
it was theorized that if DE alone could hold the average bacterial pop-
ulation in the chill system below the level existing at Foster Farms,
the required conditions would be met. To this end, a system was built,
as shown in Figure 5, to test for these results. Samples were taken
periodically from the pilot chill tank, and from a point on the output
side of the DE filter.
As Table 10 shows, DE alone is capable of removing in excess of
99% of all bacteria present and will maintain the level of bacteria in
the chill tank below the current level.
17
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DE Body Feed (2.0 g/min)
ims Wast'f
(0.2 gpm)
PILOT CHILL
TANK
DE
MIXER
UV
LIGHT
FLOW
METER
Uluadynamics No. 500
NOTL:: DH used =• cclite 512; oqui/iileni
pcre »ize = 0.5 11.
PUMP
FILTER
Area = 1.13 »q ft
Figxvre 4. A pilot recycling system without activated carbon.
DE Body Feed (2.0 g/min)
Fostor F?ims Wotei
(0.2 gpm)
PILOT CHILL
TANK
I
l
DE
MIXER
j FLOW
1 METER
»
PUMP
FILTER
NOTE. OF usod » Celite 512.
Area - 1.13 Sq ft
Figure 5. A pilot recycling system without activated carbon
or ultaviolet light.
18
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Table 9. BACTERIOLOGICAL RESULTS OF PILOT SYSTEM WITHOUT ACTIVATED CARBON
Sample Point
Average Total Bacteria
Count (cells/ml)
Percent
Reduction
Foster Farms Watei
Pilot Chill Tank
After DR
After UV
1500 x l(T
381 x 10a
1 x 10a
Zero
99.74%
100.00
TABLE 10. BM^TERIOLOGICAL RESULTS OF PILOT SYSTEM WITHOUT
.ACTIVATED CARBON OR ULTRAVIOLET LIGHT
Sample Point
Average Total Bacteria
Count (cells/ml)
Percent
Reduction
Foster Fawns water
Pilot chill tank
After DR
121.5 x
79.7 x 10-
0.56 x
99.3'/b
19
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SECTION III
SUMMARY
The specific objective of this project was to reduce the amount of
water used and the effluent total solids in poultry slaughtering plants.
In this study, only poultry chill water was used. Feasibility of both
the technical and economical aspects of the recycling system were con-
sidered. The results should be applicable to other areas in poultry
processing plants and to other food processing industries.
Data summarized in Table 11 shows the effects of recycling systems
using (1) DE, (2) DE plus UV, and (3) DE plus activated carbon plus UV on
total solids and total bacterial count. With systems (1), (2), and (3)
the total bacterial count in the pilot chill tank, after 3 hours of
operation was 73%, 33% and 20% of the levels found in the nonrecycled
system currently used. In terms of percentages, these figures may seem
to be significant to a lay-man, but from a microbiological viewpoint the
reductions obtained by use of activated carbon and UV light are not sig-
nificantly different from that obtained by DE alone. Compared to materi-
al entering the system, the output from the recycled system shows signi-
ficant reduction in total bacterial count. Since the DE system consider-
ed maintained the pilot chill tank at a bacterial level below that of
the nonrecycled system, there is no need and no advantage to using expen-
sive activated carbon and UV units.
Figure 6 depicts the proposed recycling system, which has a turbidi-
ty meter that will control two valves for recycling through the filter
if DE does break through the filter leaves.
IMPACT OF PROPOSED RECYCLING SYSTEM
The real significance of the recycling system can be realized by
considering that for the 11 billion pounds of poultry processed in the
United States in 1970, approximately 1.5 to 2 billion gallons of water
could have been saved had such a recycling system been in use. Further,
approximately 4 million pounds of suspended solids and 5 to 6 million
pounds of BOD would have been removed before the water was released. If
we consider that these figures are for the chill system alone and that
the water from the chill system represents only 5 to 6% of the water used,
large savings can be realized by recycling water in other areas.
Although such figures justify recycling water in the poultry indus-
try, further impetus can be given to such a program when energy savings
are considered. The following potential energy savings can be assumed
for the proposed DE filtration system:
20
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TABLE 11. TOTAL SOLIRS AND TOTAL BACTERIAL COUNT COMPARISONS OF THREE
WATER RECYCLING SYSTE2-E VERSUS CONVENTIONAL SYSTEM USED IN CHILLING POULTRY
Total Bacterial Count
ays tern
Conventional chill
tank
DE
System output
Chill tank
DE + UV
System output
Chill tank
DE + AC -i- UV
System output
Chill tank
I .
N/ml
•1.5 x 106
7.9 x 103
1.1 x Itf
0
5.0 x 105
1.1 x 10s
3.0 x 10B
Per Cent of
Conventional
0.5%
73.3
0
33.3
7.3
20.0
Total Solids
nig/liter
1032
299
386
357
410
489
509
Per Cent of
Conventional
29.0%
37.4
34.5
39.7
47.4
49.3
Notes: DE = Diatomaceous Earth
AC = Activated Carbon
UV " Ultraviolet light
21
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Cold Water tcf (30 gpm)
HEAT EXCHANGE
CHILLERS
50 gpm
PRECHiLLERS
Drain
DE
FEED
500 gpm
450 gpm
50 gpm
PUMP
FILTER
Rccirculation
Line
NOT!,: A turbidity meter to detect pressure of DE and control valve* 0 for safety purposes, that it,
prevent DE from entering chiller.
Figure 6. Rough schematic diagram of proposed diatomaceous earth
filter system.
22
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Well water temperature = 68°F
Prechiller water temperature = 52 F
Overflow in present system is 50 gpm for 18 hours
50% efficiency for refrigeration units
. Cost of electrical power = $0.0108/kWhr
Chiller water temperature = 34°F
. Cost of water (in & out) = $0.13/1000 gallons
Prechiller dumped thrice/shift
Chiller dumped once/shift
Chiller volume = 8,050 gallons
Prechiller volume = 1,450 gallons
Diatomaceous earth purchased in 10 ton lots (50-day supply) at
$66/ton
Using such assumptions for the proposed system, the cost calculations
outlined in the following section can be made.
23
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Outline of Cost Calculation for Proposed Recycling System
I. Expenses in Present Chilling System that Will be Eliminated by
Proposed System
A. Expense due to 100 gpm overflow.
1. Energy lost
100 gal 60 min 18 hour 8.33 Ib ,„„„ . A „ „_. .
- 7= — x — - - x — - - x - r - x 16 F= 14.4 MBtu/Oay
min hour day gal
(Well temp - overflow temp = 16°F)
14.4 x 10s Btu 2.928 x 10"* kWh 0 , ,,. . . . .
- x - ; - — x 2 (efficiency factor) =
Day Btu ,
8.45 x Iff kWh/day
8.45
2. Cost of Water
100 g*1 x 60 min x 18 hr x $0'13 = $14.00/Day
min hr day 1000
B. Expense Due to Dumping Chiller (IX) and Prechlller (3X)
1. Energy lost
dump day gal
3dumps 8.33 Ib
dump day gal
Chillers + Prechillers =2.88 MBtu/Day
2.88 x 10s Btu 2.928 x 10~* kWh
34°F = 2.3 MBtu
=
Day Btu
x $0.0108
x 2 (efficiency factor)
= $18.21/Day x two systems = $36.42
kWh
2. Cost of Dumped Water
8,050 gal + 4,350 gal = 12,400 gal
12,400 gal x $0.13
1000
—. = 1.61/day x two systems = $ 3.22
24
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C. Total Expense Incurred by Overflowing And Dumping Two Chill
Systems
Overflow cost = $105.26
Dumping cost = 39.64
Total = $146.90/day
The above figure is the cost incurred by operating two complete
chilling systems at 50-gpm overflow each for 18 hours. This figure
also includes, dumping each chiller once and dumping each prechiller
three times. The dumpings made at the end of the day are not taken
into account since they are also included in our proposed system.
II. Additional Cost to Operating DE Filtration System With Complete
Recycling (No Overflow)
A. Cost of DE (maximum values used here)
day Ib
B. Cost of Electrical Pumping
40hp Filter Pump
-3hp Present pumping system (estimated)
37hp Added
0.7457 fcWhr $0.0108 ._ „ ,.
37hp x 18hr x hpHr x ^ = $5.36 /day
C. -Total with no overflow
Cost of DE = $13.20
Added Elect. = 5.36
Total $18.56/day
D. Total savings with no overflow
Present system = $ 146.90/day
Cost (no overflow)= 18.56
Total = $ 128.34 /day
25
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III. Additional Cost to Operating DE Filtration System with 15 gal
Equivalence of Ice per Minute to Five Needed Refrigeration that
Cannot be Accomplished with Heat Exchanges.
A. Cost of DE
Same as with complete recycle = $13.20/day
B. Cost of electrical pumping same as with complete recycle =
$5.36/day
C. Energy lost with 15-gpm overflow (30 gpm considering both
systems)
. .
mm hr day gal
8.9 x id5 Btu 2.928 x 10~*kWhr „ ,„„„. , * ., ,.
- - - x - — - x 2 (Efficiency factor)
day Btu J
'• — = $56.29/day (overflow temperature = 35°F)
KiVii r
D. Cost of water at 30-gpm overflow
30 gal 60 min 18 hr $0.13 A, „, ._,
— 7s — x — - - x — - - x ,--- - . = $4.21/day
min hr day 1000 gal
E. Total with 30-gpm overflow
Cost of DE $13.20
Cost of electricity 5.36
Energy lost 56.29
Water cost 4.21
Total $79..06/day
F. Total savings with 30-gpm overflow
Present system $ 146.90
30-gpm cost 79.06
Total $ 67.84/day
26
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Please note that manpower and equipment costs have been omitted.
The system will require constant attention during its check-out period,
but can easily be made semi-automatic. Total manpower requirements,
should not exceed six hours per day.
Other factors such as the sewage treatment cost savings from the
reduced BOD in the effluent water and the reduction of bacteria in the
chill tank system cannot be put into monetary terms at this time.
27
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APPENDIX
CONVERSION FACTORS
English to Metric
English Unit
cents per thousand gal .
cubic foot
cubic inch
degree Fahrenheit
feet per second
foot(feet)
gallon(s)
-gallons per day
gallons per minute
horsepower
inch(es)
parts por mill ion
pound(s)
•pounds per square in.
square inch
ton(short)
Abbrev.
£/1 ,000 gal .
cf
cu in.
deg F
fps
ft
gal.
gpm
fcp
in.
ppm
Ib
psi
sq in.
ton
Multi.
0.264
28.32
16.39
0.0164
0.555
F-32"
0.305
0.305
3.785
1.381 x 10"5
0.0631
0.746
2.54
1.0
0.454
453.6
0,0703
6.452
S07.2
0.907
Abbrev.
C/1,000 1
1
cu cm
1
deg C
m/sec
m
1
I/sec
I/sec
kw
cm
mg/1
kg
9
kg/sq cm
sq cm
kg
metric ton
He trie Unit
£ per M liters
liter
cubic centi.
liter
degree Celsius
meters per sec.
meter(s)
litcr(s)
liters per sec.
liters per sec.
kilowatts
centimeter
mill, per liter
kilogram
grams
kilo, per sq.
centimeter
sq- centimeter
kilogram
metric ton
28
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TECHNICAL REPORT DATA
(I li'ase read Instructions on the reverse before com/'lclinx)
i HI com NO.
EPA-600/2-78-Mq
2.
3. RECIPIENT'S ACCESSION NO.
1. I I I I.I AND Slllll I I LL
RECYCLING OF WATER IN POULTRY PROCESSING PLANTS
5. REPORT DATE
March 1978 issuing date
6. PERFORMING ORGANIZATION CODE
AU I HOIKS)
Rogers, C. J.
8. PERFORMING ORGANIZATION RtPORT NO.
I. Pt Rt-OHMING ORGANIZATION NAML AND ADDRESS
Stanford Research Institute
Menlo Park, CA 94025
10. PROGRAM ELEMENT NO.
1BB037
11. CONTRACT/GRANT NO
S-800930
:1. SPONSORING AGI.NCY NAME AND ADDRESS
Industrial Environmental Research Laboratory-Cin, OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Summary
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLt MF.NTARY NOTES
16. ABSTRACT
Studies were conducted on recycling chiller water in a poultry processing
plant. The recycling system must be provided with the capability of removing
solids and controlling the microbial population.
UV was used to control the microbial population. For this control to be
effective, solids must be removed to a level to allow light transmission. Methods
studied include: 1) cyclonic desludgers, 2) vibrating screens, 3) flotation cells,
4) centrifugal waste concentration, 5) filtration with diatomaceous earth (DE)
filter aid, arid 6) activated carbon.
Pilot-scale results showed that DE filtration was the most feasible option
and that it maintained the bacterial level below that of the nonrecycled system.
Operating costs for the DE filtration system with 30 gallons equivalence of ice
per minute are $79.06/day. Normal operating costs of the chiller without recycle
are $146.90/day, thus a savings of $67.84/day. These do not include manpower and
equipment costs. Figures are calculated based on a system that overflowed
100 gpm for an 18 hour day.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI I iel(l/(;roll|)
Industrial Water, Water Consumption,
Circulation, Disinfection,
Filtration, Diatomaceous Earth,
Industrial Wastes, Poultry Meat
Poultry Processing
Wastes, Recycling,
Chiller Water, Solids
Removal. Ultraviolet.
68C
680
!. Ul!>l HIUIJI ION i'.TATfcMENT
Release to Public
19. SECURITY CLASS (This Report/
21. NO. OF PAGES
37
20. SECURITY CLASS (This page)
22. PRICE
EPA Form ?220-1 (9-73)
29
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