-------
Grinding Cooking
Curing Canning
Pickling Slicing
Smoking Packaging
Raw Wastewater
from
Packinghouse
Figure 6. Operating and Wastewater Flow (ihart
for Low- and High-Processing Packinghouses
-------
High-Processing Packinghouses
Table 5 summarizes the plant and raw waste characteristics of high"
processing packinghouses. Nineteen of the 85 plants analyzed were high-
processing packinghouses. The range of data for the 19 plants is large
for all wasteload parameters. The range of 0.4 to 2.14 for the ratio of
processed products to LWK suggests that much of the wasteload variations
caused by the wide variation in processing, relative to kill. Plant
size as measured by kill ranges from small to large; two plants were
small, 11 medium, and 6 large.
Discussion of Raw Wastes
The data in Tables 2 through 5 cover a waste water flow range of 1334 to
20,261 1/1000 kg LWK (160 to 2427 gal/1000 Ib LWK); a wasteload range of
1.5 to 30.5 kg BOD5/1000 kg LWK (1.5 to 30.5 lb/1000 Ib LWK); and a kill
range of 18.5 to 1498 kkg LWK/day (40 to 3300 thousand Ib/day). A
comparison of the data from Tables 2 and 3 for simple and complex
slaughterhouses shows that the averages of all the waste parameters are
higher for a complex plant. This was expected because, by the method of
categorization of slaughterhouses, complex slaughterhouses conducted
more secondary (by-product) processes.
The data listed in Tables 4 and 5 for low- and high-processing packing-
houses show that high-processing plants have much higher average values
for all waste parameters on a LWK basis.
Some variations in waste water flow and strength within any one of the
four subcategories can be attributed to differences in the amount and
types of operations beyond slaughtering, such as by-product and prepared
meat processing, and the effectiveness of material recovery in primary
in-plant treatment. However, the major causes of flow and wasteload
variations are variations in water use and in housekeeping practices.
Excess water use removes body fluids and tissues from products and
conveys them intcf the waste water. The effect of waste water flow on
wasteload is discussed in more detail later in this Section.
In all four subcategories, statistical correlation analysis of the data
revealed that the raw BODS wasteload correlates very well with suspended
solids, with grease, and with Kjeldahl nitrogen on a LWK basis. This
means that an increase (decrease) in one parameter will account for a
certain predictable increase (decrease) in another of the parameters.
The effect of plant size (kill) on wasteload as measured by BOD5 for
each category was assessed by a regression analysis as outlined in
Section III. The results showed that larger plants tend to have
slightly higher pollutional wasteloads. This trend is not caused by
41
-------
differences in processing. Rather, it results from some of the plants
operating at ever increasing throughput, often beyond the LWK for which
the plant was designed. Under these circumstances, housekeeping and
water management practices tend to become careless. As a result, line
speed-up overloads fixed operations such as inedible rendering and blood
handling with consequent increases in raw waste loads.
Only four small plants were included in the analysis; two were simple
slaughterhouses and two were high-processing packinghouses. Three of
the four were substantially below the average BODS wasteload for their
subcateogry, suggesting that small plants can meet effluent limits of
larger plants. The only other information available on small plants is
that of Macon and Cote. * Accurate waste data were obtained on ten
small packinghouses in 1961. Because there was insufficient information
on these plants to subcategorize them as low- or high-processing
packinghouses, and the plants were not identified, the results were not
used in determining wasteloads for the various subcategories. Those
plants that practiced blood recovery had BOD5 wasteloads between 2.7 and
8.3 kg/1000 kg LWK; the other plants which sewered blood had
considerably higher waste loads. Although some of the data did not
include the waste load from clean-up, Macon determined that the clean-up
could add from 0,35 to 3.0 kg BOD5/1000 kg LWK. These results indicate
that the waste load from small packinghouses not sewering blood is
slightly less than those from larger packinghouses. This further
substantiates that standards set for medium and large plants can be met,
without special hardship, by a small plant, if the small plant is
properly equipped for blood disposal, paunch handling, and similar high
waste-related operations.
Data in Tables 2 through 5 show that chlorides and phosphorus values are
less frequently measured than are values for the other parameters. From
the data reported, however, chlorides and phosphorus are dependent on
in-plant operations and housekeeping practices. For example, large
amounts of chlorides contained in pickling solutions and used in the
processing of ham, bacon, and other cured products ultimately end up in
the waste waters. This explains the unusually high chloride values for
high-processing packinghouses, i.e., four to six times the values for
the other subcategories, where relatively large amounts of products are
cured.
Very little useful information on other waste parameters such as
Kjeldahl nitrogen, nitrites, nitrates, ammonia, and total dissolved
solids were reported by the 85 plants whose data were summarized by
subcategory in this section. However, some information on these
parameters was obtained from other sources 7 and from field verification
studies conducted
-------
I
0)
H
ja
ta
H
rH
CO
0
H
rH
ca
*a
rH
tu
u
c
0)
tn
CO
01
u
o
a-
cn
3
t-i
O
O-
(fi
O
CL,
tn
•o
•H
l-i
O
2
U
c
at
00
0
rl
-H
"8
T3
01
a*
to
3
0
rl
U
ra
*;
cn
u
3
TD
0
0-
w
CO
T-i
CO
Cfl
tA
n)
cu
tn
CO
01
r<
O
in
•a
•H
rH
O
ir
O
§
iH
•H
I
rH
TJ
Ot
tn
cu
u
o
t-i
x
cn
u
3
•a
o
£
00
c
c
0
rH
oc
•*
00
J^
0
o
0
rH
00
^
00
^
0
o
0
rH
00
00
e
o
c
rH
00
00
O
o
o
rH
00
OC
O
c
0
rH
j?
00
o
o
o
tH
"H
•H
O
03
00
o
0
o
•H
1-J
I-J
, 1
g
01
•a
"ob
o
0
o
rH
^
Of
(A
M
CM
m
"*— '
rH
CM
O
CM
^-.
CM
n
tn
C
n)
rH
P-.
MH
O
rl
flJ
E
•X
iH
0
m
m
rH
O
CO
fO
m
0
o
CO
m
rH
CO
CM
CO
OJ
00
n)
OJ
£
o^
o
o
CM
o
CM
o
rH
CM
O
^j
^
0
rH
O
g
•H
CO
•H
a>
CO
T3
C
«
tn
i
o
o
t
c
C1
m
O
o
1
in
o
i
o
o
1
CO
o
1
' M)
0
1
CM
I
CO
1
00
•H
O
CM
00
•H
.C
1
O
rH
at
00
C
*
CM
fl
O
(N
**
rH
cr.
CO
rH
CO
rH
0->
CO
rH
O
o
o
r-.
rH
CO
o
•rl
4J
CO
•H
)-l
(U
J-l
O
n)
^3 ca
u cu
co
cu 3
w o
co -C
at oo
* ^
S>3
cd
PL.
•a
99
*rt
4-1 CO
a co
n) a)
H a
PM o
rl
M-I PH
o i
>i oo
M H
n) W
la
w m
I
•3
H
r-t
rt
4-1
O
H
rH
rH
01
/
01
in
cn
01
o
o
p-i
tn
M
O
G.
Cft
O
.C
P-.
cn
•H
V4
0
J2
U
c
CO
to
cr,
rH
m
"- '
o
*~*
rH
^
Cp
rH
in
u
C
BJ
rH
PH
>4-l
O
01
g
o
m
o
•H
O
CO
o
m
0
Cpi
o
rH
rH
rH
O
m
co
rH
C*l
rH
0)
00
at
<
o
o
CM
CM
O
CO
rH
rH
CS
cr,
o
CO
tH
x£>
CO
as
CO
o
•H
4-1
CO
>
•a
ca
•0
C
«
C/l
1
0
1
1
CN
1
CO
o
1
o
CO
CM
1
rH
1
fM
vC
1
CO
CO
1
^
JC
00
•H
4T
I
8
**-i
o
01
tc
e
«3
&
o
C"|
O
co
CN
0
r~»
CM
m
CM
CM
0
CM
rH
vO
CN
0
CM
43
-------
during this program. Typical ranges are given below for these waste
parameters. It should be noted that the values for dissolved solids in
the waste water are also affected by the dissolved solids content of the
plant water supply.
Nitrates and Nitrites as N, mg/1 0.01 - 0.85
Kjeldahl nitrogen, mg/1 50 - 300
Ammonia as N, mg/1 7 -» 50
Total dissolved solids, mg/1 500 - 25,000
Bacteria are present in the raw waste from meat packing plants. The
usual measure is in terms of coliforms, and for these the MPN (most
probable number) typically is in the range of 2 to H million per 100 ml.
The process waste water normally is warm; it averages about 32°C (90°F);
it reaches a high of about 38°C (100°F) during the kill period, and a
low of about 27°C (80°F) during cleanup. Biological treatment processes
operate best und^r warm conditions; e.g., the optimum for anaerobic
lagoons is about 32°C (90°F); hence, they are facilitated by the waste
water temperature.
The pH of the process waste water is typically in the range of 6.5 to
8.5, although on occasion it may be outside this range. An alkaline pH
is important in the operation of anaerobic lagoons, as long as it does
not get above this range.
PROCESS FLpW DIAGRAMS
The most typical flow arrangement used in the meat packing industry is
shown schematically in Figure 7. The system is used in about 70 percent
of the plants studied. The figure shows that most of the waste water
flows through a recovery system which consists of screening followed by
a catch basin. Frequently, the only waste streams to by-pass this
system are the pen washing, sanitary wastes, hog scalding and dehairing
wastewaters, and hide-processing waste waters. Pen washings normally
pass through a manure trap and then are mixed with the other waste
waters before entering further treatment for discharge to a watercourse
or a
-------
Raw
Water
Animal Pens
(may follow
catch basins)
By-Product Operations
Blood
„ . I
Hair p
Tripe
Rendering
Casing
Saving
^
/
> /•
^
(except hair & h
V
Facilities
/
ides)
Domestic Uses
Laundry
Facilities
Blc
tier
jwdown
Cooling
Boiler
Blowdown
Treatment
(Industrial or
Municipal)
Figure 7. Typical Wastewater Treatment Systeir
Without Dissolved Air Flotation
-------
municipal sewer. Only noncontaminated water, such as cooling water,
completely by-passes treatment; it usually discharges directly to a
stream. In plants in which barometric condensers are used, the water
can become contaminated. Most of this water is sent to further treat-
ment.
The second most frequently used waste water arrangement is shown
schematically in Figure 8. In this flow arrangement, several low
grease bearing streams by-pass the screen and catch basin. This permits
an increase in the detention time of the grease-bearing stream in a
grease recovery system because the system can now handle a lower waste
water flow. Low-grease-bearing waste waters normally originate from the
pens, some secondary (by-product) processing, and sanitary wastes. This
arrangement is commonly used when dissolved air flotation is included in
primary treatment. A portion of the effluent from the flotation unit is
recycled to a pressurization tank where air is added for flotation.
Several modifications of the flow arrangement shown in Figure 8 are used
by the industry. Some plants add chemicals to the waste stream via a
mixing tank just prior to the flotation unit. This usually increases
grease and solid recovery but it also may increase the moisture content
of the skimmings to 85 to 95 percent, making the handling of skimmings
more difficult. Other plants may have twp dissolved air flotation units
in series. Chemicals are usually added to the waste stream entering the
second unit. Skimmings from the first unit are almost always rendered
while those from the second unit, which contain chemicals, may be
landfilled. A few plants add chemicals to both units to achieve a high
wasteload reduction. Chemicals may reduce the rendering efficiency or
produce a finished grease that is unacceptable on the market.
A third flow arrangement, which has been installed in a few recently
built plants, is shown in Figure 9. The purpose of this arrangement is
to segregate waste streams according to the type of treatment to be
applied. In the scheme shown, the streams are divided into low and high
grease-bearing streams, and manure-bearing streams. For example, floor
drains located on the kill floor after the carcass is opened, are
connected to the high grease-bearing streams; hide processing waste
water is directed to the manure-bearing streams. Segregation into the
three major waste streams permits optimum design of each catch basin and
flotation unit for recovery and waste load reduction, with minimum
investment in equipment. A more detailed list of the segregated stream
contents is given by Johnson* 8
Although there are a number of operations where waste water could be
reused or recycled, the industry is generally recycling or reusing only
non-contaminated cooling water, as illustrated in Figures 7, 8, and 9.
One minor exception is reuse of lagoon water as cooling water.
-------
Slaughtering
Hide Removal
Evisceration
(may follow
ratch basins)
Dissolved
Air
Flotation
Scalding & Hair
Removal
Wet Well
& Pumps
By-Product Operations
Receiving
Body of
Water
Figure 8. Typical Wastewater Treatment System
Including Dissolved Air Flotation
-------
tn
1
w
*-* &
U rH 0
0) 0) 3
3 IS FM
-53
bO CJ
C -H CO
•H *J C
0) -W «J QJ
C nl w a)
•H )^ CO M
fe 43 O
•H l-i CA
> 0
Ml
C
•H
OJ
cq
I
0)
en
n)
0)
S-i
bO
B
•H
tti
0)
FQ W
I 5-1
01 Ol
W 4-1
o) 3
M 01
CJ 4-1
to
m n3
o s
4-1 60
c c
O) -H
4-J ttj
cfl Ol
H 01
01 p
4-J B
tfl CTJ
tfl
ft T3
0) B
01
(-1
3
bO
•H
-------
WATER USE _-r WASTELOADRELATIONSHIPS
Increased water use causes increased pollutional wasteload in the meat
packing industry. This was verified by regression and correlation
analyses of individual plant data over long periods (up to two years) ,
and also on the data for each of the four subcategories. For example,
multiple regression analysis of the data relating BOD5 wasteload to kill
and flow revealed that a variation of one standard deviation would
change the predicted EOC5 for a simple slaughterhouse by 1.0 kg/1000 kg
LWK (1.0 lb/1000 Ib LWK); it would change the predicted load for a
complex slaughterhouse fcy 2.8 kg/1000 kg LWK (2.8 lb/1000 Ib LWK).
Another regression analysis between BODS and flow on a LWK basis showed
that one standard deviation in flow changed the predicted BOD5 by 5.6
and 5.3 kg/1000 kg LWK (5.6 and 5.3 lb/1000 Ib LWK) for low- and high-
processing packinghouses, respectively.
Figure 10 shows the average and range of the results of separate
regression analysis on the flow-wasteload data from each of eleven
plants. This figure clearly illustrates that water use strongly affects
the pollutional wasteload. For example, the figures show that a 20
percent reduction in water use would, on the average, result in a BODS
reduction of 3.5 kg/1000 kg LWK (3.5 lb/1000 Ib LWK).
Further evidence for the dependence of pollutional wasteload on water
flow is that, in three of the four subcategories, the plant with the
lowest wasteload also had the lowest water use. In the fourth sub-
category, the plant with the lowest wasteload had the second lowest
water use.
Low water use, and consequently low absolute wasteload, requires
efficient water management practices. For example, available data
showed that two simple slaughter houses practice very good water use
practices. The plants both had wasteloads of about 2 kg/1000 kg LWK (2
lb/1000 Ib LWK); their wastewater flows ranged from 1333 to 2415 1/1000
kg LWK (166 to 290 gal/1000 Ib LWK) . One plant was an old beef
slaughterhouse; the other, a new hog slaughterhouse. This outstanding
performance was achieved in a sugcategory for which the flows ranged to
21,000 1/1000 kg LWK (1750 gal/1000 Ib LWK), and for which the BOD5
loading ganged to over 14 kg/1000 kg LWK (14 lb/1000 Ib LWK).
48
-------
15-
0>
O
O
O
\
o»
IO
o
o
CD
10-
5-
Range
Average for
Individual Plants
X
0
Gal/1000 Ibs LWK
500 IOOO
I i
0
2000
I
l
4000 6000
Liters/IOOO kg U/VK
r
8000 10,000
Figure 10. Effect of Water Use on Wasteload
for Individual Plants
-------
SOURCES OF WASTEWATER
Animal Pens
Although pen wastes only contain an estimated 0.25 kg of BOD5/1000 kg
LWK, 9 the wastes are high in nutrients. 10 Frequently, the solid
wastes are removed by dry cleaning, followed by little or no washdown.
If the pens are washed down, a manure trap is frequently used to recover
solids rather than letting them enter a treatment system. Any rainfall
or snowmelt runoff is normally contained and routed for treatment with
other raw waste flows.
Another waste water source in the pens is the watering troughs. Each
trough may discharge 8 1/min (2.1 gal/min) or more. With perhaps 50 or
more pens in a large plant, the1 water source becomes significant. The
total waste from the pens, however, is a minor contributor to the waste
load.
Slaughtering
The slaughtering operation is the largest single source of wasteload in
a meat packing plant, and blood is the major contributor. Blood is rich
in BOD5, chlorides, and nitrogen. It has an ultimate BOD of 405,000
mg/1 and a BODS between 150,00 and 200,000 mg/1. i» Cattle contain up to
50 pounds of blood per animal, and typically only 35 pounds of the blood
are recovered in the sticking and bleeding area. The remaining 15
pounds of blood are lost as wastes which represents a wasteload of 2.25
to 3.0 kg BOD5/1000 kg LWK (2.25 to 3.0 lb/1000 Ib LWK). Total loss of
the blood represents a potential BOD5 wasteload of 7.4 to 15 kg/1000 kg
LWK (7.5 to 15 lb/1000 Ib LWK). Because very few meat plants practice
blood control outside of the bleeding area, the typical BOD5 load from
blood losses in the slaughtering operation is estimated to be 3 kg/1000
kg LWK. In beef plants, much of this loss occurs during hide removal.
Beef paunch or rumen contents is another major source of waste load.
Paunch manure, which contains partially digested feed material, has a
BOD5 of 50,000 mg/1. 12 At an average paunch weight of 50 pounds per
head, dumping of the entire contents can contribute 2.5 kg/1000 kg LWK.
However, the common practices are to either screen the paunch contents,
washing the solids on the screen (wet dumping), or to dump on a screen
to recover the solids, allowing only the "juice" to run to the sewer
(dry dumping). Because 60 to 80 percent of the BOD5 in the paunch is
water soluble, wet dumping of the paunch represents a BOD5 loss of about
1.5 kg/1000 kg LWK. If dry dumping is practiced, the pollutional waste-
load is much less than this. When none of the paunch is sewered but is
processed or hauled out of the plant for land disposal, paunch handling
does not contribute to the wasteload. Cooking of the rumen or paunch in
a hot alkaline solution (tripe processing) will also add to the waste-
50
-------
load, particularly to the grease load. The strong alkalinity of these
waste waters may also make grease recovery more difficult.
The hog scald tank and dehairing machine are other sources of pollution.
The overflow from a hog scald tank is usually about 8U 1/1000 kg LWK (10
gal/1000 Ib LWK) at a BODS loss of about 3000 mg/1. This could
represent a BOD5 loss of about 0.25 kg/1000 kg LWK. Continuous overflow
of water from the dehairing machine is estimated to contribute a maximum
BODS load of O.U kg/1000 kg LWK.
Other sources of waste from the slaughtering of animals and dressing of
carcasses is from carcass washing, viscera and offal processing, and
from stomach and peck flushing.
The offal operations such as chitterling washing and cleaning casinqs
intestinal can contribute to the pollution load of a plant. T1 tne
slime waste from the casings is not sewered, the wasteload from thfse
operations would be greatly reduced.
The highest source of water use in slaughtering is from the washing of
carcasses; an extreme example for which data are available shows rates
of 2915 1/min (350 gal/min). Flushing the manure from chitterling an 1
viscera, or conveyer sterilizing, and the tripe "umbrella" washer are
other high water use operations.
Meat_Processing
The major pollutants from meat processing are meat extracts, meat and
fatty tissue, and curing and pickling solutions. Loss of these
solutions can be the major contributor to the waste load from
processing. The results of a recent study showed that only 25 percent
of the curing brine remained in the product. 11 The rest of the hrine
is lost to the sewer. This source of chlorides, plus others such as
from hide curing and the use of salt on the floors to reduce
slipperiness, explains why some packinghouse wastes have high chlorides.
A content of 1000 nig/1 of chlorides is not uncommon in the effluent from
a packinghouse. Another constituuent of the cure is dextrose; it has a
BOD5 eguivalent of 2/3 kg/kg (Ib/lb). Conseguently, packinghouses with
a sizeable curing facility will have high BOD5 waste unless the wastes
from curing are segregated or recycled. In one plant over 2000 pounds
of dextrose was lost daily. 13 The pollution load from meat and fatty
tissue can be substantially reduced by dry clean-up prior to washdown.
The water use in meat processing should be primarily limited to cleanup
operations and to product washing, cooling, and cooking.
51
-------
Secondary Manufacturing Processes
Secondary manufacturing processes, as described in Section IV, are those
by-product operations within the industry for the handling, recovery,
and processing of blood, trimmings, and inedible offal. This includes
paunch and viscera handling, hide processing, hair recovery and
processing, and edible and inedible rendering. Those viscera and offal
operations that occur on the slaughtering floor, such as paunch handling
and tripe processing, were considered under slaughtering.
The hashing and washing of viscera, often performed prior to rendering,
produces a strong waste load with a BOD5 value of about 70,000 mg/1. 11
The waste conservation trend in the past few years has been toward not
hashing and washing prior to rendering, but sending the uncleaned vis-
cera directly to rendering. In one plant, removal of the hasher and
washer reduced the BOC5 to the waste treatment plant by 910 kg (2000
pounds) per day, with an attendant increase in the rendered animal feed
production.
Efficient recovery of hog hair is now practiced widely within the
industry, although the market for this by-product has been reduced in
recent years. Very few plants hydrolyze hog hair, but rather wash and
bale for sale or dispose of it directly to land fill. The waste load
from the recovery and washing of the hair is estimated to contribute
less than 0.7 kg/1000 kg LWK.
Hide curing operations are becoming increasingly involved at meat
packing plants. Just a few years ago many plants were shipping hides
green or in salt pack. Today, however, many beef slaughter operations
include hide curing in tanks, vats, or raceways. The hides, prior to
being soaked in brine, are washed and defleshed. These washings, which
are sewered, contain blood, dirt, manure, and flesh. In most defleshing
operations the bulk of the tissue is recovered. In addition to these
wastes, soaking the hide in the brine results in a net overflow of
approximately 7.7 liters (2 gallons) of brine solution per hide. In a
few plants the brine in the raceway is dumped weekly, whereas in others
it is dumped yearly or whenever the solids build up to a point where
they interfere with the hide curing operation. The life of the brine
can be extended by pumping the recycled brine over a vibrating or static
screen. The waste load from the overflow and washings in a typical hide
curing operation, where the hide curing wastes are not frequently
dumped, is about 1.5 kg/1000 kg LWK for BODS and about U kg/1000 kg LWK
for salt.
Blood processing may be either wet or dry. Continuous dryers, which are
quite common, use a jacketed vessel with rotating blades to prevent
burn-on; this process results in low losses to the sewer (estimated to
contribute about 0.3 kg BOD5/1000 kg LWK). Continuous ring dryers are
sometimes used: they produce a relatively small amount of blood water
52
-------
that, in some small plants, is discharged to the sewer. The old
technique of steam sparging the blood to coagulate it is still
frequently used. The coagulated blood is separated from the blood water
by screening. The blood water has a BODS of about 30,000 mg/1. It is
often sewered, contributing a waste load of about 1.3 kg/1000 kg LWK.
This loss can be eliminated by evaporating the blood water, either by
itself or by combining it with other materials in conventional inedible
dry rendering operations.
Wet rendering and low temperature rendering are potentially large
sources of pollution. Tank water from wet rendering can have a BODS
value of 25,000 to 45,000 mg/1, and the water centrifuged from low
temperature rendering can have a BODS of 30,000 to 40,000 mg/1. It is
estimated that sewering of either of the waste streams produces a waste
load of 2 kg BODS/1000 kg LWK. These waste loads can be eliminated by
evaporation or combining with other materials used in dry inedible
rendering. Triple-effect vacuum evaporators are often used to concen-
trate the "tankwater" from the wet rendering operation. The wasteload
from wet rendering is primarily caused by overflow or foaming into the
barometric leg of these evaporators and discharge to the sewer or,
sometimes directly tc a stream. From dry rendering the pollution comes
from the condensing vapors, from spillage, and from clean-up operations.
A recent study revealed that a typical dryer used 454 to 492 1/min (120
to 130 gal/min) of water for condensing vapors, and that the^ effluent
contained 11Q mg/1 of BODS and 27 mg/1 grease. The estimated wasteload
from dry rendering is 0.5 kg/1000 kg LWK.
Cutting
The main pollutants from cutting operations are meat and fat scraps from
trimming, and bone dust from sawing operations. Most of these
pollutants enter the wastje stream during clean-up operations. These
wastes can be reduced by removing the majority of them by dry clean-up
prior to washdown, and also by some form of grease trap in the cutting
area. The collected material can be used directly in rendering. Pone
dust is a large source of phosphorus and, when mixed with water, does
not settle out readily; thus it is difficult to recover, and should be
captured in a box under the saw.
Clean-UjD
Macon6 found that clean-up contributes between 0.3 and 3 kg BODS/1000 kg
LWK in small packinghouses. Data collected by the Iowa Department of
Environmental Quality showed that anywhere from 27 to 56 percent of the
total BODS waste load is contained in the clean-up waste waters. The
clean-up operation thus is a major contributor to the waste load. it
also leads to a significant loss of recoverable by-products. Detergents
53
-------
used in clean-up can adversely affect the efficiency of grease recovery
in the plant catch basin.
The techniques and procedures used during clean-up can greatly influence
the water use in a plant and the total pollutional waste load. For
example, dry cleaning of floors prior to wash down to remove scraps and
dry scraping of the blood from the bleed area into the blood sewer are
first steps. A light wash down, again draining to the blood sewer,
before the normal washdown definitely decreases the pollution load from
clean-up.
-------
SECTION VI
SELECTION OF POLLUTANT PARAMETERS
SELECTED PARAMETERS
Based on a review of the Corps of Engineers Permit Applications from the
meat packing plants, previous studies on waste waters from meat packing
plants, 3,is industry data, questionnaire data, published reports, 1*
and data obtained from sampling plant waste waters during this study,
the following chemical* physical, and biological constituents constitute
pollutants or measures of pollution as defined in the Act.
BODS (5 day, 20°C biochemical oxygen demand)
COD (Chemical cxygen demand)
Suspended solids
Dissolved solids
Grease
Ammonia nitrogen
Kjeldahl nitrogen
Nitrates and nitrites
Phosphorus
Chloride
Temperature
Bacteria
PH
On the basis of all evidence reviewed, there do not exist any purely
hazardous types of pollutants (such as heavy metals or pesticides) in
the waste discharged from the meat processing plants.
RATIONALE FOR SELECTION OF IDENTIFIED PARAMETERS
5- Day Biochemical f Oxygen^ De
This parameter is an important measure of the oxygen consumed by micro'
organisms in the aerobic decomposition of the wastes at 20°C over a
five-day period. More simply, it is an indirect measure of the bio-
degradability of the organic pollutants in the waste. BOD5 can be
related to the depletion of oxygen in a receiving stream or to the
requirements for waste treatment. Values of BOD5 range from 300 to 3800
mg/1 in the raw waste, although typical values range from 900 to 1500
mg/1.
If the BODS level of the final effluent of a meat packing plant into a
receiving body is too high, it will reduce the dissolved oxygen level in
that stream to below a level that will sustain most fish life; i.e.,
55
-------
below about U mg/1. Many states currently restrict the BOD5 of
effluents to below 20 mg/1 if the stream is small in comparison with the
flow of the effluent. A limitation of 200 to 300 mg/1 of BODS is often
applied for discharge to municipal sewer, and surcharge rates often
apply if the BOD5 is above the designated limit.
A 20-day biochemical oxygen demand (BOD20) , sometimes called "ultimate"
BOD, is usually a better measure of the waste load than BOD5. However,
the test for BOD20 requires 20 days to run, so it is an impractical
measure for most purposes.
COD is yet another measure of oxygen demand. It measures the amount of
organic and some inorganic pollutants under a carefully controlled
direct chemical oxidation by a dichromate-sulfuric acid reagent. COD is
a much more rapid measure of oxygen demand than BODS, and is potentially
very useful. However, it does not have the same significance, and at
the present time cannot be substituted for BODS because COD: BODS ratios
vary with the types of wastes.
COD provides a rapid determination of the waste strength. Its measure-
ment will indicate a serious plant or treatment malfunction long before
the BODS can be run. A given plant or waste treatment system usually
has a relatively narrow range of COD: BODS ratios, if the waste
characteristics are fairly constant, so experience permits a judgment to
be made concerning plant operation from COD values. In the industry,
COD ranges from about 1.5 to 5 times the BODS; the ratio may be to the
low end of the range for raw wastes, and near the high end following
secondary treatment when the readily degraded material has been reduced
to very low levels.
Suspended^§oj.ids
This parameter measures the suspended material that can be removed from
the waste waters by laboratory filtration, but does not include coarse
or floating matter that can be screened or settled out readily. Sus-
pended solids are a visual and easily determined measure of pollution
and also a measure of the material that may settle in tranquil or slow-
moving streams. Suspended solids in the waste from meat packing plants
correlate quite well with BODS. A high level of suspended solids is an
indication of high BOC5. Generally, suspended solids range from one-
third to three-fourths of the BODS values in the raw waste. Suspended
solids are also a measure of the effectiveness of solid removal systems
such as clarifiers and fine screens.
56
-------
Dissolved Solids
•» -^ —• •« ^ T* • ' •«. " • •" - '•
The dissolved solids in the raw waste water are mainly inorganic salts,
and the salt present in the largest amount is sodium chloride (described
below). Loadings of dissolved solids thus vary to a large extent with
the amount of sodium chloride entering the waste stream. However,
values of 1500 mg/1 or more may be encountered. The dissolved solids
are particularly important in that they are relatively unaffected by
biological treatment processes. Unless removed, the salts may
accumulate in recycle or reuse systems within a plant. The presence of
sulfates is a further hindrance to treatment systems since sulfates are
reduced to sulfides (causing odors) in anaerobic system. The dissolved
solids at discharge concentrations may be harmful to vegetation and
preclude various irrigation practices. Specific data for dissolved
solids in treated effluents is limited; the technical sophistication and
cost of salt removal systems is high and beyond the scope of even the
best current treatment systems addressed in this study. Limitations on
dissolved solids are therefore not being specified at this time. This
same circumstance applies to chlorides (a dissolved salt) which are
described below in more detail.
Grease
Grease, also called oil and grease, or hexane solubles, is a major
pollutant in the raw waste stream of meat packing plants. The source of
grease is primarily from carcass dressing, washing, trimming, viscera
handling, rendering and clean-up operations. Grease forms unsightly
films on the water, interferes with aquatic life, clogs sewers, disturbs
biological processes in sewage treatment plants, and can also become a
fire hazard. The loading of grease in the raw waste load varies widely,
from 0.25 to 27 kg/1000 kg LWK (0.25 to 27 lb/1000 Ib LWK). This would
correspond to an average concentration of about 650 mg/1. Grease may be
harmful to municipal treatment facilities particularly to trickling
filters.
Amjnon i a ^ Ni t r ocjen
Ammonia nitrogen in raw waste is just one of many forms of nitrogen in a
waste stream. Anaerobic decomposition of protein, which contains
organic nitrogen, leads to the formation of ammonia. Thus, anaerobic
lagoons or digesters produce high levels of ammonia. Also, septic
(anaerobic) conditions within the plant in traps, basins, etc., may lead
to ammonia in the waste water. Another source of ammonia can be leakage
to ammonia refrigeration systems; such systems are still fairly common
in meat packing plants.
57
-------
Ammonia is oxidized by bacteria in a process called "nitrification" to
nitrites and nitrates. This may occur in an aerobic treatment process
and in a stream. Thus, ammonia will deplete the oxygen supply in a
stream; its oxidation products are recognized nutrients for aquatic
growth and for some toxic qualities (see below). Also, free ammonia in
a stream is known to be harmful to fish.
A typical concentration in the raw waste load is about 7.0 to 50.0 mg/1;
however, after treatment in an anaerobic secondary system, the con-
centrations of ammonia can reach as high as 100 to 200 mg/1. Ammonia is
limited in drinking water to 0.05 to 0.1 mg/1. **
K-jeldahl,. Nitrogen
This parameter measures the amount of ammonia and organic nitrogen; when
used in conjunction with the ammonia nitrogen, the organic nitrogen can
be determined by the difference. Under septic conditions, organic
nitrogen decomposes to form ammonia. Kjeldahl nitrogen is a good
indicator of the crude protein in the effluent and, hence, of the value
of material being lost in the waste water. The protein content is
usually taken as 6.25 times the organic nitrogen. The sources of
Kjeldahl nitrogen are basically the same as for ammonia nitrogen, above,
except for the refrigeration system. The raw waste loading of Kjeldahl
nitrogen is extremely variable and highly affected by blood losses.
Typical loadings range from O.OU to 6.76 kg/1000 kg LWK (0.04 to 6.76
lb/1000 Ib LWK), and concentrations range from about U to 750 mg/1.
Typical raw waste concentrations of Kjeldahl nitrogen are between 50 and
300 mg/1.
Nitrates^and Nitrites
Nitrates and nitrites, normally reported as N, are the result of oxida-
tion of ammonia and of organic nitrogen. They may also enter the waste
stream from use in the plant as preservatives- Nitrates are important
in the water supply used for human or livestock consumption, because
high nitrate concentrations can be toxic. Nitrates are essential
nutrients for algae and other aquatic plant life and should be
minimmized to preclude eutrophication in watercourses.
58
-------
Phosphorus
Phosphorus, commonly reported as P, is another primary nutrient for
aquatic plant life and can therefore cause eutrophication in water
courses. The threshold concentration of phosphorus in receiving bodies
that can lead to eutrophication is about 0.01 mg/1. The primary source
of phosphorus in raw waste from meat packing plants is bones and
detergents. The total phosphorus in the raw effluent ranges from about
0.01 to 0.63 kg/1000 kg LWK (0.01 to 0.63 lb/1000 Ib LWK), or a
concentration range of 15 to 50 mg/1.
Chlorides
Chlorides in concentrations greater than 5000 mg/1 can be harmful to
people and other animal life. High chloride concentrations in waters
can be troublesome for certain industrial uses and for reuse or
recycling of water. The major sources pf chlorides from meat packing
plants are the salt from animal tissues, hide curing operations,
pickling and curing solutions, cleaning chemicals, blowdown water, and
that used to prevent slipping on floors. The concentrations in raw
waste are extremely variable from plant to plant, and are normally
higher for plants killing cattle and treating hides than they are for
other plants. The amount in the waste is an indicator of the way in
which certain processes are being operated. The range of chloride
loadings in raw waste effluents is from less than one to greater than 20
kg/1000 kg LWK (20 lb/1000 Ib LWK). Chloride loadings are unaffected by
biological treatment systems used by the industry today, and once in the
waste waters they are very costly to remove. As a result, limitations
are not being established at this time.
Temperature
Because of the long detention time at ambient temperatures associated
with typically large biological treatment systems used for treating meat
packing waste water, the temperature of the final effluent from most
packing plants will be virtually the same as the temperature of the
receiving body of water. Noncontaminated cooling waters that are
discharged directly will tend to have a maximum of 40-U3°C (105-110°F)
during the summer months, and will be cooler at other times of the year.
The quantity of this cooling water is small compared with the process
waste water flow. The temperature of the raw waste typically averages
about 32°C (90°F), with a high of about 38°F (100°F) during the kill
59
-------
period and a low of about 27°C (80°F) during the clean-up period. These
temperatures are an asset for biological treatment of the waste,
maintaining high rates cf growth of the microorganisms upon which the
treatment depends.
Colif orm Bacteria
The coliform bacteria contamination of raw waste is substantially
reduced in the waste treatment systems typically used in the industry
such as anaerobic lagoons followed by large aerobic lagoons. Colif orms,
measured as "total" or "fecal", serve as indicators of potential
pathogenic organisms. Data indicate that the MPN of the total coliform
of the raw waste from meat packing plants is in the 2- to 4-million per
100 ml range. In the final effluent of a typical anaerobic-aerobic
system, the MPN per 100 ml is usually several thousand. Typically,
states require that the fecal coliform count not exceed 50-200 MPN/100
ml for waste waters discharged into receiving waters. Hence, most final
effluents require chlorination to meet state standards as well as to
assure effective waste treatment.
The usual pH for raw waste falls between 6.5 and 8.5; unusual processes
such as hog hair hydrolyzing may raise this slightly, but not enough to
significantly offset treatment effectiveness or effluent quality.
However, some adjustment may be required, particularly if pH adjustment
has been used to lower the pH for protein precipitation, or if the pH
has been raised for ammonia stripping. The pH of the waste water then
should be returned to its normal range before discharge. The effect of
chemical additions for pH adjustment should be taken into consideration,
as new pollutants could result.
Others
Some other pollution parameters are of lesser significance. Color is
related to a number of factors such as color of raw wastes (blood) ,
treated waste (lagoon effluent) , raw waste strength, and is a visible
indicator; it is useful only for qualitative purposes. Odor is only a
problem in the waste water in anaerobic treatment systems., or if
aerobic systems become anaerobic. A build-up of grease on the surface
of the anaerobic lagoon is sometimes utilized to functionally reduce
odor. However, high sulfate water supply sources may aggravate
malordorous conditions,
60
-------
SECTION VII
CONTROL AND TREATMENT TECHNOLOGY
SUMMARY
The wasteload discharged from the meat packing industry to receiving
streams can be reduced to desired levels, including no discharge of
pollutants, by cpnscientious waste water management, in-plant waste
controls, process revisions, and by the use of primary, secondary, and
tertiary waste water treatment. Figure 11 is a schematic of a suggested
waste reduction program for the meat packing industry to achieve high
removal of pollutants in subsequent treatment.
This section describes many of the techniques and technologies that are
available or that are being developed to achieve the various levels of
waste reduction. In-plant control techniques and waste water management
suggestions are described first. Waste treatment technology normally
employed as a primary treatment is then described. In the case of the
meat packing industry this "primary" treatment is a materials recovery
process, and is considered as part of the in-plant system, although many
of these systems have been improved for reducing pollutional levels.
The effluent from these processes is considered the "raw waste".
Secondary treatment systems, which are employed in the treatment of the
raw waste, are presented with a description of the process, the specific
advantages and disadvantages of each system, and the effectiveness on
specific waste water contaminants found in packing plant waste. The
tertiary and advanced treatment systems that are applicable to the waste
from typical packing plants are described in the last part of this
section. Some of these advanced treatment systems have not been used in
full scale on meat packing plant waste; therefore, the development-
status, reliability, and potential problems are discussed in greater
detail than for the primary ,and secondary treatment systems which are in
widespread use.
The wasteload from a meat packing plant is composed of a waste water
stream containing the various pollutants described in Section VI. The
cost and effectiveness of treatment of the waste stream will vary with
the quantity of water and the wasteload. In fact, as indicated in
Section V, the pollutional wasteload increases as water use increases.
In-plant control techniques will reduce both water use and pollutional
wasteload. The latter will be reduced directly by minimizing the entry
61
-------
of solids into the waste water stream and indirectly by reducing water
use.
The in-plant control techniques described below have been used in
packing plants or have been demonstrated as technically feasible.
Waste Reduction
Techniques
Waste Reduction
Effect
Point of
Application
Waste
Water
Mgmt . &
In-Plant
Controls
^
Water-
Flow 6,
Waste
Load
Reduction
^
Plant
Operations
Screening,
Skimming,
Settling -
Primary
Treat.
By-Product
Recovery,
Grease,
& Coarse
Solids
Removal
i
f
In-Plant
Figure 11. Suggested Meat Packing Industry Waste Reduction Program
62
-------
Pen Wastes
The best livestock hglding pens are covered and dry cleaned with only
periodic washdown as required by Department of Agriculture regulations.
Bedding material and manure are readily disposed of on farm land as
fertilizer. A separate sewer and manure pit are provided for liquid
wastes from the pens; disposal is on land or to the secondary treatment
system. Drinking water in the pens is minimized and based on need.
Watering troughs should have automatic level controls.
Blood Handling
In good practice, blood is not sewered. Blood is almost totally
contained and collected in a blood collection system. Water or steam
are not necessary to operate such a system, and both should be avoided.
After dry cleaning the floors and walls exposed to blood flows and
splashing, a first water wash, using a minimum amount of water, can be
drained into the blood collection system. 18 Bloodwater can be avoided
by installing a blood dryer. If a plant handles bloodwater, it should
not be sewered, but can be rendered, evaporated, or mixed with paunch
and cooked to produce a feed material. ia Blood drying in direct feed
dryers for use as a feed material has been demonstrated on a full scale.
40 Blood collection by a vacuum system may be a feasible process if
markets for edible blood develop. Very limited amounts of edible blood
are collected for pharmacuticals. In general, improved blood collection
methods need to be developed to match the high production rate of
American plants.
Paunch
The use of water in the initial dumping of paunch material or in pumping
it must be discontinued. Dumping the entire paunch contents (including
the liquid) for disposal or treatment without sewering, followed by a
high pressure but minimal water rinse of the paunch will minimize the
pollutional wasteload from this operation. Consideration should also be
given to vacuuming out the residual material instead of washing it out.
In each case the economics of recovery of the paunch and cost of the
resulting waste treatment should be examined and compared to direct
rendering of the paunch, as is.
Liquids screened from the paunch material should be collected and
evaporated or rendered, not wasted. Plants that presently slurry the
paunch with water for pumping should either install a solids handling
pump, thus avoiding the need for a water slurry, or devise an alternate
63
-------
handling technique; e.g., transporting the entire unopened paunch to
rendering.
Viscera Handling
The production necessity of the inedible hashing and washing operation
is subject to conjecture. Inedible viscera can be rendered without
washing. A good quality grease may be obtained if the washings of
edible viscera (i.e., chitterlings) are collected in a catch basin in
the immediate area before sewering. 1(> The grease and solids wasteload
from the viscera can be commensurately reduced through such by-product
recovery techniques. Caustic washings from any viscera processing
should be segregated before sewering to minimize grease saponification
and to avoid a high pH in the waste water.
Troughs
Troughs have been installed under the killing floor carcass conveying
line to keep as much blood, trimmings, bone dust, and miscellaneous
pieces off the floor as possible. The troughs have proven very
effective in collecting and containing solids, blood, etc., that under
ordinary circumstances would have ended up in the sewer. Substantial
wasteload reductions are evident in the plants using these troughs.
Variations in animal size may be a problem; however, if large variations
are rare, some acccmodation should be possible. A squeegee or scraper
shaped to fit the trough is used in clean-up to move all collected
materials to the inedible rendering system.
Rendering
Both wet and dry rendering are used for edible, as well as inedible,
rendering processes; although the trend is toward dry rendering. In
processing lard, low^ or medium-temperature continuous rendering systems
are common. The water centrifuged from this process can be sold as 50
to 60 percent edible "stickwater" and thus should be evaporated and not
discharged to the sewer.
In dry rendering, sprays are commonly used to condense the vapors. In
inedible dry rendering, catch-basin effluent can be reused as condenser
water. In edible dry rendering, the vapors are commonly condensed with
fresh water. A direct heat exchanger can be used to condense the vapors
without increasing waste water volumes.
In wet rendering, the greases are drawn off the top of the tank, then
the water phase (tankwater) is removed. This tankwater has a BOD5
-------
ranging from 22,000 mg/1 to as high as 45,000 mg/1 and suspended solids
as high as 2 percent. Under no circumstances can this type of waste he
discharged to the sewer. It must be evaporated and the end product,
commonly called stick or stickwater, is then blended into animal feed
materials. The tankwater may also be dried directly with inedible
solids in a dry rendering tank. The bottom sludge from wet rendering is
pressed for recovery of residual grease, and the remaining solids
(cracklings) are used as edible product from edible rendering, and as
animal feed ingredient from inedible rendering.
Even if the tankwater is evaporated, pollution can occur. Triple-effect
vacuum evaporators can readily foam over, further contaminating the
waste water.
Hide Processing
An overflow of water from the hide curing vat or raceway occurs because
water is added to the curing solution and because hides dehydrate as
they take on salt. This overflow could be contained and collected
separately, allowing a more intensive treatment, at a reasonable cost,
to achieve a higher quality effluent, especially in terms of salt
concentrations. It is especially important to dump the raceway
infrequently—perhaps only annually. When dumped, it should be drained
gradually, over a period of 24 hours or more, to avoid an extreme shock
load on the treatment system. The life of the solution can be extended
by pumping it over a static or vibrating screen.
Scald Tank
The hog scald tank contains settled solids and waste water with a high
wasteload. Collection, treatment, and reuse of this water should be
considered. Slow drainage of the tank will reduce any shock load on the
waste treatment system and should be standard practice. Provision
should be made for the removal of the solids through the bottom of the
tank to a truck for land disposal.
Pickle and Curing Solutions
These solutions are high in salt content and, in many curing solutions,
high in sugar content. Salt is a difficult pollutant to remove and
sugar has a very high BODS, The operations involving injection or
soaking of meat products in these solutions should be equipped to
collect all of the solution presently wasted. The collection pans and
equipment should be designed to permit reuse of these solutions. 10,17
65
-------
Water Conservation Practices
The following practices and equipment should be employed to reduce the
water consumption in plants with coincidental reduction of the
pollutional wasteload: 10,17
1. Replace all drilled spray pipe systems with spray nozzles
designed and located to provide a desired water spray
pattern.
2. Replace all washwater valves with squeeze- or press-to-
open valves wherever possible. Foot- or knee-operated
valve control is useful where operator fatique is a
problem or where the operation requires the operator
to work with both hands.
3. Install foot-pedal operated handwashing and drinking
fountain water valves to eliminate constnatly running
water.
4. Install automatic control for sprays which need to
operate only about 50 percent of the time.
5. Product chillers using cold water may be economically
replaced by chillers using a cryogenic liquid such as
nitrogen, thus reducing water consumption and perhaps
improving product quality.
6. The boiler blowdown is potentially reusable and
should be considered for use in clean-up or in the plant
laundry. Detergent use will be reduced as well as water
conserved.
7. Plant clean-up as an operating procedure consumes a
substantial quantity of water in most plants. Reduced
water use can be achieved with equipment such as high
pressure water spray systems, steam and water mix
spray systems, or automated clean-in-place (CIP) systems.
Management ccntrol is particularly vital in clean-up
operations if water is to be conserved and cleanliness
standards are to be maintained.
8. Whenever possible, water should be reused in lower
quality needs. Examples include carcass washwater
reused for hog dehairing, and lagoon water reused for
cooling. The general axiom is: use the lowest quality
of water satisfactory for the process.
66
-------
Clean-Up Operations
In addition to water conservation practices, other steps can also be
taken to reduce the wasteload from clean-up: floors and other surfaces
should be dry squeegeed or scraped wherever feasible, to keep a maximum
amount of solids and grease out of the waste water; pull the drain
basket only after cleanup has been completed; use the minimum of water
and detergent, consistent with cleaning requirements, and automate the
cleaning of conveyors, piping and other equipment.
67
-------
IN-PLANT PRIMARY TREATMENT
Flow Equalization
Equalization facilities consist of a holding tank and pumping equipment
designed to reduce the fluctuations of waste streams. They can be
economically advantageous whether the industry is treating its own
wastes or discharging into a city sewer after some pretreatment. The
equalizing tank will store waste water either for recycle or reuse or to
feed the flow uniformly to treatment facilities throughout the 24hour
day. The tank is characterized by a varying flow into the tank and a
constant flow out.
The major advantages of equalization for the meat packer are that
treatment systems can be smaller, since they can be designed for the 24-
hour average rather than the peak flows, and secondary waste treatment
systems operate much better when not subjected to shockloads or
variations on feed rate.
Screens
Since so much of the pollutional matter in meat wastes is originally a
solid (meat particles and fat) or sludge (manure solids) , interception
of the waste material by various types of screens is a natural first
step. To assure best operation for application to the plant waste water
stream, a flow equalization facility should precede it.
Unfortunately, when these pollutional materials enter the sewage flow
and are subjected to turbulence, pumping, and mechanical screening, they
break down and release soluble BOD5 to the flow, along with colloidal
and suspended and grease solids. Waste treatment—that is, the removal
of soluble, colloidal and suspended organic matters-is expensive. it is
far simpler and less expensive to keep the solids out of the sewer
entirely.
Static, vibrating, and rotary screens are the primary types used for
this step in the in-plant primary treatment. Whenever feasible, pilot-
scale studies are warranted before selecting a screen, unless specific
operating data are available for the specific use intended, in the same
solids concentration range, and under the same operating conditions.
68
-------
Static gcreens
The primary function of a static screen is to remove "free" or trans-
porting fluids. This can be accomplished in several ways and, in most
older concepts, only gravity drainage is involved. A concavely curved
screen design using high velocity pressure-feeding was developed and
patented in the 1950's for mineral classification and has been adapted
to other uses in the process industries. This design employs bar inter-
ference to the slurry which knives off thin layers of the flow over the
curved surface. 17
Beginning in 1969, United States and foreign patents were allowed on a
three-slope static screen made of specially coined curved wires. This
concept used the Coanda or wall attachment phenomena to withdraw the
fluid from the under layer of a slurry which is stratified by controlled
velocity over the screen. This method of operation has been found to be
highly effective in handling slurries containing fatty or sticky fibrous
suspended matter. 17
The arrangement of transverse wires with unique singular curves in the
sense of flow provides a relatively non-clogging surface for dewatering
or screening. The screens are precisely made in No. 316 stainless steel
and are extremely rugged. Harder, wear-resisting stainless alloys may
also be used for special purposes. Openings of 0.025 to 0.15 cm (0.010
to 0.060 inches) meet normal screening needs. *7
yibrating_Screens
The effectiveness of a vibrating screen depends on a rapid motion.
Vibrating screens operate between 900 rpm and 1800 rpm; the motion can
either be circular or straight line, varying from 0.08 to 1.27 cm (1/32
to 1/2 inch) total travel. The speed and motion are selected by the
screen manufacturer for the particular application.
Of prime importance in the selection of a proper vibrating screen is the
application of the proper cloth. The capacities on liquid vibrating
screens are based on the percent of open area of the cloth. The cloth
is selected with the proper combination of strength of wire and percent
of open area. If the waste solids to be handled are heavy and abrasive,
wire of a greater thickness and diameter should be used to assure long
life. However, if the material is light or sticky in nature, the
durability of the screening surface may be the smallest consideration.
In such a case, a light wire may be necessary to provide an increased
percent of open area.
69
-------
Rotary Screens
One type of barrel cr rotary screen, driven by external rollers,
receives the waste water at one open end and discharges the solids at
the other open end. The liquid passes outward through the screen
(usually stainless steel screen cloth or perforated metal) to a
receiving box and effluent sewer mounted below the screen. The screen
is usually sprayed continuously by means of a line of external spray
nozzles. The screen is usually inclined towards the solids exit end.
This type is popular as an offal screen but has not been used to any
great extent in secondary "polishing11—that is, in removing solids from
waste streams containing low solids concentrations. 17 (A screen of
this type has been developed for recycle of hide brining waters.)
Another rotary screen commonly used in the meat industry is driven by an
external pinion gear. The raw flow is discharged into the interior of
the screen below center, and solids are removed in a trough and screw
conveyor mounted lengthwise at the center line of the barrel. The
liquid exits outward through the screen into a box in which the screen
is partially submerged. The screen is usually 40 x 40 mesh, with 0.4 mm
(1/64 inch) openings. Perforated lift paddles mounted lengthwise on the
inside surface of the screen assist in lifting the solids to the
conveyor trough. This type is also generally sprayed externally to
reduce blinding. Grease clogging can be reduced by coating the wire
cloth with teflon. Solids removals up to 82 percent are reported. »7
Applications
A broad range of applications exist for screens as the first stage of
inplant primary treatment processes. These include both the plant waste
water and waste water discharged from individual processes. The latter
include paunch manure, hog stomach contents, hog hair recovery,
stickwater solids, hide washing operations, hide curing brine recycle,
and others.
Catch Bas3.ns
The catch basin for the separation of grease and solids from meat
packing waste waters was originally developed to recover marketable
grease. Since the primary object was grease recovery, all improvements
were centered on skimming. Many catch basins were not equipped with
automatic bottom sludge removal equipment. These basins could often be
completely drained to the sewer and were "sludged out" weekly or at
frequencies such that septic conditions would not cause the sludge to
rise. Rising sludge was undesirable because it could affect the color
and reduce the market value of the grease.
70
-------
In the past twenty years, with waste treatment gradually becoming an
added economic incentive, catch basin design has been improved in the
solids removal area as well. In fact, the low market value of inedible
grease and tallow has reduced concern about quality of the skimmings,
and now the concern is shifting toward overall effluent quality improve-
ment. Gravity grease recovery systems will remove 20 to 30 percent of
the BODS, 40 to 50 percent of the suspended solids and 50 to 60 percent
of the grease (hexane solubles). 1*
The majority of the gravity grease recovery basins (catch basins) are
rectangular. Flow rate is the most important criterion for design; 30
to 40 minutes detention time at one hour peak flow is a common sizing
factor. 17 The use of an equalizing tank ahead of the catch basin
obviously minimizes the size requirement for the basin. A shallow
basin—up to 1.8m (6 feet)—is preferred.
A "skimmer" skims the grease and scum off the top into collecting
troughs. A scraper moves the sludge at the bottom into a submerged
hopper from which it can be pumped. Both skimmings and sludge go to by-
product recovery.
Usually two identical catch basins, with a common wall, are desirable so
operation can continue if one is down for maintenance or repair. Both
concrete and steel tanks are used.
Concrete tanks have the inherent advantages of lower overall maintenance
and more permanence of structure. However, some plants prefer to be
able to modify their operation for future expansion or alterations or
even relocation.
All-steel tanks have the advantage of being semiportable, more easily
field-erected, and more easily modified than concrete tanks. The all-
steel tanks, however, require additional maintenance as a result of wear
from abrasion.
A tank using all-steel walls and concrete bottom is probably the best
compromise between the all-steel tank and the all-concrete tank. The
advantages are the same as for steel; however, the all-steel tank
requires a footing underneath the supporting members, whereas, the
concrete bottom forms the floor and supporting footings for the steel
wall tank.
Dissolved Air^Flotation
As a materials recovery concept, dissolved air flotation is actually
functioning to treat wastes.
71
-------
However within the context of this report, therefore the effluent from a
dissolved air flotation system is considered raw waste. This system is
normally used to remove fine suspended solids and is particularly
effective on grease in waste waters from meat packing plants. This is a
relatively recent technology in the meat industry; however, it is in
fairly widespread use and increasing numbers of plants are installing
these systems.
Dissolved air flotation appears to be the single most effective device
that a meat packing plant can install to reduce the pollutional
wasteload in its waste water stream. It is expected that the use of
dissolved air flotation will become standard practice in the industry,
especially as a step in achieving the 1977 or 1983 standards.
Technical Description
Air flotation systems are used to remove any suspended material from
waste water with a specific gravity close to that of water. The
dissolved air system generates a supersaturated solution of waste water
and compressed air by raising the pressure of the waste water stream to
that of the compressed air, then mixing the two in a detention tank.
This supersaturated mixture of air and waste water flows to a large
flotation tank where the pressure is released, thereby generating
numerous small air bubbles which effect the flotation of the suspended
organic material by one of three mechanisms: 1) adhesion of the air
bubles to the particles cf matter; 2) trapping of the air bubbles in
the floe structures of suspended material as the bubbles rise; 3)
adsorption of the air bubbles as the floe structure is formed from the
suspended organic matter. *8 In most cases, bottom sludge removal
facilities are also provided.
There are three process alternatives varying by the degree of waste
water that is pressurized and into which the compressed air is mixed.
In the total pressurization process. Figure 12, the entire waste water
stream is raised to full pressure for compressed air injection. In
partial pressurization. Figure 13, only a part of the waste water stream
is raised to the pressure of the compressed air for subsequent mixing.
In the recycle pressurization process (Alternative B of Figure 13),
treated effluent from the flotation tank is recycled and pressurized for
mixing with the compressed air and then, at the point of pressure
release, is mixed with the influent waste water. Alternative A (Figure
13) shows a side-stream of influent entering the detention tank, thus
reducing the pumping required in the system shown in Figure 12.
Operating costs may vary slightly, but performance should be essentially
equal among the alternatives.
72
-------
o
•H
4J
n)
4J
O
H
M
•H
-------
o o
•*- u>
O
II
a
"O if)
•Is
c
.0
o
Kl
1 Pressuri;
.0
a
Q_
^
Process
ternative
<
a
o
a)
4-1
o
•8
O
CO
to
•rl
Q
CO
0)
4-1
n)
CO
CO
a)
a
o
M
0)
M
00
•H
-------
Improved performance of the air flotation system is achieved by
coagulation of the suspended matter prior to treatment. This is done by
pH adjustment or the addition of coagulant chemicals, or both. Aluminum
sulfate, iron sulfate, limer and polyelectrolytes are used as coagulants
at varying concentrations up to 300 to UOO mg/1 in the raw waste. These
chemicals are essentially totally removed in the dissolved air unit,
thereby adding little or no load to the downstream waste treatment
systems. Chemical precipitation is also discussed later, particulary in
regard to phosphorus removal, under tertiary treatment; phosphorus can
also be removed at this primary (in-plant) treatment stage. A slow
paddle mix will improve coagulation. It has been suggested that the
proteinaceous matter in meat packing plant waste could be removed by
reducing the waste water to the isoelectric pH range of about 3.5. 19
The protein material would be coagulated at that point and, readily
removed as float from the top of the dissolved air unit. This is a
typical practice in the meat industry in the United States at the
present
However, a somewhat comparable practice involving by-product recovery is
gaining acceptance. In this system, segregated sewers are required
along with two stages of air flotation treatment of the waste waters. A
good quality grease product can be recovered from a grease~bearing waste
water without the addition of chemicals in the first dissolved air
system. The effluent from the first dissolved air unit is mixed with
effluent from the other waste streams in the plant and this is fed to
the second dissolved air unit which may or may not include chemicals
addition, as mentioned above.
One of the manufacturers of dissolved air flotation equipment indicated
a 60 percent suspended solids removal and 80 to 90 percent grease
removal without the addition of chemicals. With the addition of 300 to
400 mg/1 of inorganic coagulants and a slow mix to coagulate the organic
matter, the manufacturer says that 90 percent or more of the suspended
solids can be removed and more than 90 percent of the grease. 20 Total
nitrogen is also reduced as exemplified by the 35 to 70 reduction
efficiencies for the air flotation units for which data were available
for this study.
North Star's staff observed the operation of several dissolved air units
during the verification sampling program and other plant visits. One
plant that was visited controlled the feed rate and pH of the waste
water and achieved 90 to 95 percent removal of solids and grease. Other
plants had relatively good operating success, but some did not achieve
the results that should have been attainable. It appeared that they did
not fully understand the process chemistry and were using erroneous
operating procedures.
The Alwatec process has been developed by a company in Oslo, Norway, and
uses a lignosulfonic acid precipitation and dissolved air flotation.
75
-------
recovering a high protein product that is valuable as a feed. 21 Nearly
instantaneous protein precipitation and hence, nitrogen removal is
achieved when high protein-containing effluent, such as that from a meat
packing plant, is acidified to a pH between 3 and U, and high molecular
weight fully sulphonated^ sodium lignosulphonate is added. BODS
reduction is reported to range from 60 to 95 percent and the recovered
protein material leads to a reduction of nitrogen in the effluent of 85
to 90 percent The effluent must be neutralized before further treatment
by the addition of milk of lime or some other inexpensive alkali. This
process is being evaluated on meat packing waste in one plant in the
United States at the present time.
Problems and Reliability
The reliability of the dissolved air flotation process and of the
equipment seems to be well established, although it is relatively new
technology for the meat packing industry. As indicated above, it
appears that the use of the dissolved air system is not fully exploited
by some of the companies who have installed them for waste water treat-
ment. The potential reliability of the dissolved air process can be
realized by proper installation and operation. The feed rate and
process conditions must be maintained at the proper levels at all times
to assure this reliability. This fact does not seem to be fully
understood or of sufficient concern to some companies, and thus full
benefit is frequently not achieved.
The sludge and float taken from the dissolved air system can be disposed
of with the sludges obtained from secondary waste treatment systems.
The addition of polyelectrolyte chemicals was reported to create some
problems for sludge dewatering; however, this may have been the unique
experience of one or tvvo meat packing plants. The mechanical equipment
involved in the dissolved air flotation system is fairly simple,
requiring standard maintenance attention for such things as pumps and
mechanical drives.
BIOLOGICAL WASTEWATER TREATMENT SYSTEMS
The biological treatment methods commonly used for the treatment of meat
packing wastes after in-plant primary treatment (solids removal) are the
following biological systems; anaerobic processes, aerobic lagoons,
variations of the activated sludge process, and high-rate trickling
filters. Based on operational data from a pilot-plant system, the
rotating biological contactor shows potential as a secondary treatment
system. Several of these systems are capable of providing 70 to 97
percent BODS reductions and 80 to 95 percent suspended solids reduction,
while combinations of these systems can achieve reductions greater than
99 percent in BOD5 and grease, and greater than 97 percent in suspended
solids.
76
-------
The selection of a secondary biological system for treatment of meat
packing wastes depends upon a number of important system
characteristics. Some of these are waste water volume, equipment used,
pollutant reduction effectiveness required, reliability, consistency,
and resulting secondary pollution problems (e.g., sludge disposal and
odor control). The characteristics and performance of each of the above
mentioned secondary treatment systems, and also for common combinations
of them, are described below. Capital and operating costs are discussed
in Section VIII. Since the treatment of wastes does not differ for the
four subcategories of the meat packing industry (see Section IV), no
distinction by subcategory is made in the following discussion.
Anaerobic_Processes
Two types of anaerobic processes are used: anaerobic lagoons and
anaerobic contact systems. Elevated temperatures (29° to 35°C or 85° to
95°F) and the high concentrations of carbohydrates, fats, proteins, and
nutrients typically found in meat packing wastes make these wastes well
suited to anaerobic treatment. Anaerobic or faculative microorganisms,
which function in the absence of dissolved oxygen, break down the
organic wastes to intermediates such as organic acids and alcohols.
Methane bacteria then convert the intermediates primarily to carbon
dioxide and methane. Unfortunately, much of the organic nitrogen
present in the influent is converted to ammonia nitrogen. Also, if
sulfur compounds are present (such as from high-sulfate raw water—50 to
100 mg/1 sulfate) hydrogen sulfide will be generated or acid conditions
will develop which suppress methane production and create odors.
because they provide high overall removal of BOD5 and suspended solids
anaerobic processes are economical with no power cost (other than
pumping) and with low land requirements.
Anaerobic Lagoons
Anaerobic lagoons are widely used in the industry as the first step in
secondary treatment or as pretreatment prior to discharge to a municipal
system. Reductions of up to 97 percent in BOD5 and up to 95 percent in
suspended solids can be achieved with the lagoons; 85 percent reduction
in BOD5 is common. A usual arrangement is two anaerobic lagoons in
parallel, although occasionally two are used in series. These lagoons
are relatively deep (3 to 5 meters, or about 10 to 17 feet), low
surface-area systems with typical waste loadings of 240 to 320 kg
BOD5/1000 cubic meters (15 to 20 Ib BOD5/1000 cubic feet) and a
detention time of five to ten days. A thick scum layer of grease and
paunch manure is frequently allowed to accumulate on the surface of the
lagoon to retard heat loss, to ensure anaerobic conditions, and
hopefully to retain obnoxious odors. Low pH and wind can adversely
affect the scum layer.
77
-------
Plastic covers of nylon-reinforced Hypalon, polyvinyl chloride, and
styrofoam have been used on occasion in place of the scum layer; in fact
some states require this. Properly installed covers provide a
convenient means for pdcr control and collection of methane gas.
Influent waste water flow should be near, but not on, the bottom of the
lagoon. In some installations, sludge is recycled to ensure adequate
anaerobic seed for the influent. The effluent from the lagoon should be
located to prevent short-circuiting the flow and carry-over of the scum
layer. For best operation, the pH should be between 7.0 and 8.5. At
lower pH, methane-forming bacteria will not survive and the acide
formers will take over to produce very noxious odors. At a high pH
(above 8.5), acid forming bacteria will be suppressed to lower the
lagoon efficiency,
Advantages-Pisadvantages. Advantages of an anaerobic lagoon system are
initial low cost, ease of operation, and the ability to handle large
grease loads and shock waste loads, and yet continue to provide a
consistent quality effluent.21 Disadvantages of an anaerobic lagoon are
the hydrogen sulfide generated from sulfated waters and the typically
high ammonia concentrations in the effluent of 100 mg/1 or more. If
acid conditions develop, sever odor problems result. If the gases
evolved are contained, it is possible to use iron filings to remove
sulfides.
Application. Anaerobic lagoons used as the first stage in secondary
treatment "are usually followed by aerobic lagoons. Placing a small,
mechanically aerated lagoon between the anaerobic and aerobip lagoons is
becoming popular. A number of plants are currently installing extended
aeration units following the anaerobic lagoons to obtain nitrification.
Anaerobic lagoons are not permitted in some states or areas where the
gound water is high or the soil conditions are adverse (e.g., too
porous)r or because of odor problems.
78
-------
Anaerobic Contact^ System
The anaerobic contact system requires far more equipment for operation
than do anaerobic lagoons, and consequently is not as commonly used.
The equipment, as illustrated in Figure 14, consists of equalization
tanks, digesters with mixing equipment, air or vacuum gas stripping
units, and sedimentation tanks (clarifiers). Overall reduction of 90 to
97 percent in BODS and suspended solids is achievable.
Equalized waste water flow is introduced into a mixed digester where
anaerobic decomposition takes place at a temperature of about 33° to
35°C (90° to 95°F). EOD5 loadings into the digester are between 2.4 and
3.2 kg/cubic meter (0.15 and 0.20 Ib/cubic foot), and the detention time
is between three and twelve hours. After gas stripping, the digester
effluent is clarified and sludge is recycled at a rate of about onethird
the raw waste influent rate. Sludge at the rate of about 2 percent of
the raw waste volume is removed from the system.7
Advantages-Disadvantages. Advantages of the anaerobic contact system
are high organic waste load reduction in a relatively short time;
production and collection of methane gas that can be used to maintain a
high temperature in the digester and also to provide auxiliary heat and
power; good effluent stability to grease and wasteload shocks; and
application in areas where anaerobic lagoons cannot be used because of
odor or soil conditions. Disadvantages of anaerobic contactors are
higher initial and maintenance costs and some odors emitted from the
clarifiers.
Applications. Anaerobic contact systems are restricted to use as the
first stage of secondary treatment and can be followed by the same
systems following anaerobic lagoons or trickling filter roughing
systems.
Aerated Lagoons
Aerated lagoons have been used successfully for many years in a limited
number of installations for treating meat packing wastes. However, with
recent tightening of effluent limitations and because of the additional
treatment aerated lagoons can provide, the number of installations is
increasing.
Aerated lagoons use either fixed mechanical turbine^type aerators,
floating propeller-type aerators, or a diffused air system for supplying
oxygen to the waste water. The lagoons usually are 2,4 to 4.6 m (8 to
15 feet) deep, and have a detention time of two to ten days. BOD5
reductions range from 40 to 60 percent with little or no reduction in
79
-------
suspended solids. Because of this, aerated lagoons approach conditions
similar to extended aeration without sludge recycle (see below).
Advantages-Pisadvantages
Advantages of this system are that it can rapidly add dissolved oxygen
(DO) to convert anaerobic waste waters to an aerobic state; provide
additional BODS reduction; and require a relatively small amount of
land. Disadvantages are the power requirements and that the aerated
lagoon, in itself, usually does not reduce BODS and suspended solids
adequately to be used as the final stage in a high performance secondary
system,
Applications
Aerated lagoons are usually the second stage of secondary treatment and
must be followed by an aerobic (shallow) lagoon to capture residual
suspended solids and to provide additional treatment.
Aerobic Lagoons
Aerobic lagoons (or stabilization lagoons or oxidation ponds) are large
surface area, shallow lagoons, usually 1 to 2.3 m (3 to 8 feet) deep,
loaded at a BODS rate of 20 to 50 pounds per acre. Detention times will
vary from about one month to six or seven months; thus, aerobic lagoons
require large areas of land.
Aerobic lagoons serve three main functions in waste reduction:
o Allow solids to settle out;
o Equalize and control flow;
o Permit stabilization of organic matter by aerobic and
facultative microorganisms and also by algae.
Actually, if the pond is quite deep, 1.8 to 2.4 m (6 to 8 feet), so that
the waste water near the bottom is void of dissolved oxygen, anaerobic
organisms may be present. Therefore, settled solids can be decomposed
into inert and soluble organic matter by aerobic, anaerobic or
facultative organisms, depending upon the lagoon conditions. The
soluble organic matter is also decomposed by microorganisms. It is
essential to maintain aerobic conditions in at least the upper 6 to 12
inches in shallow lagoons since aerobic microorganisms cause the most
complete oxidation of organic matter. Wind action assists in carrying
the upper layer of liquid (aerated by air-water interface and photo-
80
-------
synthesis) down into the deeper portions. The anaerobic decomposition
generally occuring in the bottom converts solids to liquid organics
which can become nutrients for the aerobic organisms in teh upper zone.
Algae growth is common in aerobic lagoons; this currently is a drawback
when aerobic lagoons are used for final treatment. Algae may escape
into the receiving waters, and the algae added to receiving waters are
considered a pollutant. Algae in the lagoon, however, play an important
role in stabilization. They use CO2, sulfates, nitrates, phosphates,
water and sunlight to synthesize their own organic cellular matter and
give off free oxygen. The oxygen may then be used by other
microorganisms for their metabolic processes. However, when algae die
they release their organic matter in the lagoon, causing a secondary
loading. Lagoon discharge p^pes located about 30 cm or 1 foot below the
lagoon surface will help reduce the algae content in the effluent.
Ammonia disappears without the appearance of an aquivalent amount of
nitrite and nitrate in aerobic lagoons. From this, and the fact that
aerobic lagoons tend to become anaerobic near the bottom, it appears
that some denitrification is occurring.
Ice and snow cover in winter reduces the overall effectiveness of
aerobic lagoons by reducing algae activity, preventing mixing, and
preventing reaeration by wind action and diffusion. This cover, if
present for an extended period, can result in anaerobic conditions.
When there is no ice and snow cover on large aerobic lagoons, high winds
can develop a strong wave action that can damage dikes. Riprap,
segmented lagoons, and finger dikes are used to prevent wave damage.
Finger dikes, when arranged appropriately, also prevent short circuiting
of the waste water through the lagoon. Rodent and weed control, and
dike maintenance are all essential for good operation of the lagoons.
Adyantages^Disadyantacies
Advantages of aerobic lagoons are that they reduce suspended solids, and
colloidal matter remaining in aerated chamber or anaerobic lagoon
effluents, oxidize organic matter, permit flow control and waste water
storage. Disadavantages are reduced effectiveness during winter months,
the large land requirements, the algae growth problem, ineffectiveness
in removing residual grease, and odor problems for a short time in
spring, after the ice melts and before the lagoon becomes aerobic again.
81
-------
I
£
o>
c
o
it
0)
o
o
M
P-.
4-1
C
o
a
,£>
o
0)
0)
M
M)
•r)
fe
UJ
82
-------
Applications
Aerobic lagoons usually are the last stage in secondary treatment and
frequently follow anaerobic or anaerobic-aerated lagoons. Large aerobic
lagoons allow plants to store waste waters for discharge during periods
of high flow in the receiving body of water or to store for irrigation
purposes during the summer. These lagoons are particularly popular in
rural areas where land is available and relatively inexpensive.
Activated Sludge
The conventional activated sludge process is schematically shown in
Figure 15. In this process recycled biologically active sludge or floe
is mixed in aerated tanks or basins with waste waters. The
microorganisms in the floe adsorb organic matter from the wastes and
convert it by oxidation-enzyme systems to such stable products as carbon
dioxide, water, and sometimes nitrates and sulfates. The time required
for digestion depends on the type of waste and its concentration, but
the average time is six hours. The floe, which is a mixture of micro-
organisms (bacteria, protozoa, and filamentous types), food, and slime
material, can assimilate organic matter rapidly when properly activated;
hence, the name activated sludge.
From the aeration tank the mixed liquor waste waters, in which little
nitrification has taken place, are discharged to a sedimentation tank.
Here the sludge settles cut, producing a clear effluent, low in BOD5,
and a biologically active sludge. A portion of the settled sludge,
normally about 20 percent, is recycled to serve as an inoculum and to
maintain a high mixed liquor suspended solids content. Excess sludge is
removed (wasted) from the system, usually to thickeners and anaerobic
digestion, or to chemical treatment and dewatering by filtration or
centrifugation.
83
-------
0>
O)
to
I!
co
o I
•SI
l
(0
(0
Q)
U
O
M
a)
t>o
en
•o
0)
4J
co
I
w §,
15 ~o
t-l
0)
M
r,
84
-------
This conventional activated sludge process can reduce BODS and suspended
solids up to 95 percent. However, because it cannot readily handle the
shock loads and widely varying flow common to meat packing waste waters,
this particular version of activated sludge is not a commonly used
process for treating meat packing wastes.
Various modifications of the activated sludge process have been
developed, such as the tapered aeration, step aeration, contact
stabilization, and extended aeration. Of these, extended aeration
processes are being used for treatment of meat packing wastes.
Extended _Aeration
The extended aeraticn process is similar to the conventional activated
sludge process, except that the mixture of activated sludge and raw
waste water is maintained in the aeration chamber for longer periods of
time. The common detention time in extended aeration is one to three
days, rather than six hours. During this prolonged contact between the
sludge and raw waste, there is ample time for the organic matter to be
adsorbed by the sludge and also for the organisms to metabolize the
organic matter which they have adsorbed. This allows for a much greater
removal of organic matter. In addition, the organisms undergo a
considerable amount of endogenous respiration, and therefore oxidize
much of the organic matter which has been built up into the protoplasm
of the organism. Hence, in addition to h;Lgh organic removals from the
waste waters, up to 75 percent of the organic matter of the
microorganisms is decomposed into stable products and consequently less
sludge will have to be handled.
In extended aeration, as in the conventional activated sludge process,
it is necessary to have a final sedimentation tank. Some of the solids
resulting from extended aeration are rather finely divided and therefore
settle slowly, requiring a longer period of settling.
The long detention time in the extended aeration tank makes it possible
for nitrification to occur. In nitrification under aerobic conditions,
ammonia is converted to nitrites and nitrates by specific groups of
nitrifying bacteria. For this to occur, it is necessary to have sludge
detention times in excess of ten days.21 This can be accomplished by
regulating the amounts of sludge recycled and wasted each day. Oxygen
enriched gas could be used in place of air in the aeration tanks to
improve overall performance. This would require that the aeration tank
be partitioned and covered, and that the air compressor and dispersion
system be replaced by a rotating sparger system, which costs less to buy
and operate. When cccurrent, staged flow and recirculation of gas back
through the liquor is employed, between 90 and 95 percent oxygen use is
claimed. 22 Although this modification of extended aeration has not been
85
-------
used in treating meat packing wastes, it is being used successfully for
treating other wastes.
Advantages and Pis advantages
The advantages of the extended aeration process are that it is stable to
shock loading and flow fluctuations because the incoming raw waste load
is diluted, by the liquid in the system, to a much greater extent than
in conventional activated sludge. Also, because of the long detention
time, high BOD5 reductions can be obtained. Other advantages of the
system are the "elimination of sludge digestion equipment and the
capability to produce a nitrified effluent. Disadvantages are that it
is difficult to remove most of the suspended solids from the mixed
liquor discharged from the aeration tank; large volume tanks or basins
are required to accommodate the long detention times; and operating
costs for aeration are high.
Applications
Because of the nitrification process, extended aeration systems are
being used following anaerobic lagoons to produce low BODS and low
ammonia- nitrogen effluents. They are also being used as the first stage
of secondary treatment followed by polishing lagoons.
Tricklinc?
A trickling filter consists of a bed of rock or prefabricated plastic
filter media on the surface of which the microbial flora develops; a
rotary arm waste water distribution system; and an under-drainage
system. The distribution arm uniformly distributes waste water over the
filter media. The microflora adsorbs, and eventually metabolizes the
organic matter in the liquid as it trickles down through the media.
When the growth becomes fairly thick it begins to slough off the surface
of the media as large pieces of solids which are carried with the liquid
out through the under-drainage system. Consequently, the trickling
filter must be followed by an appropriate sedimentation tank to remove
the solids. To avoid clogging the trickling filter, the waste water
must be pre-treated (primary, in-plant treatment) to remove most solids
and grease.
The high-rate trickling filter is used in treating meat plant waste
waters either as a roughing filter preceding a conventional secondary
treatment such as activated sludge or as complete secondary treatment in
several stages. Hydraulic loading for high rate trickling filters is
generally in the range of 93.5 to 187 million liters per hectare (10 to
20 million gallons per acre) per day.
86
-------
In treating high organic wastes with trickling filters there is a
definite limit to BODS removal by a single stage. Common practice has
been to use a multistage filter system. The first stage filter can be
fed at a BOD5 rate of 0.016 to 0.024 kg/cubic meter of media (100 to 150
pounds/1000 cubic feet) and can result in 40 to 50 percent removal of
BODS. If the second stage filter is the final filter to be used, the
loading should not exceed 0.4 kg BODS/cubic meter of media (25 pounds of
BODS per 1000 cubic feet) of media. However, since the raw waste load
of meat packing plants is relatively strong, this may mean that the size
of the second filter will be excessively large. In this case, it might
be better to provide still a third stage; then loadings can be higher in
the second stage--up to 0.8 to 1.2 kg BODS per cubic meter of media (50
to 75 pounds of BOD5/1000 cubic feet of media). The loading to the
third stage should be limited to 0.32 kg of BODS/cubic meter of media
(20 pounds/1000 cubic feet). The overall removal of such a system can
be as high as 95 percent reduction in BODS. When staging of filters is
used, it is desirable tc provide a sedimentation tank for each stage.
However, large rock cr synthetic media can be used without intermediate
sedimentaton. Because of the size of second and third stage filters and
because of the number of sedimentation tanks that may be required, this
system is no longer generally used in the meat packing industry.
Although single-stage filters alone result in considerably less BODS
reduction than staged trickling filter systems, they have found use in
the meat industry, particularly as a pretreatment prior to some type of
activated sludge system.
Advantages^and^Disadvantages
Advantages of the roughing trickling filter are that it can smooth out
hydraulic and BODS loadings; provide some initial reduction in BODS (40
to 50 percent); and the fact that it is not injured materially by
extended rest periods such as weekends. However, if there are long rest
periods it is desirable to recirculate the effluent of one of the
settling tanks through the filter to keep the floe moist. Another
advantage of the roughing filter is its reliability with minimum care
and attention, A disadvantage of the trickling filter system in general
is that it is a costly installation, it may also be necessary to cover
the filters in winter to prevent freeze-up, and the effluent
concentration fluctuates with changes in incoming wasteload.
87
-------
Rotating Biological contactor
Process Description
The rotating biological contactor (RBC) consists of a series of closely
spaced flat parallel disks which are rotated while partially immersed in
the waste waters being treated. A biological growth covering the
surface of the disk adsorbs dissolved organic matter present in the
waste water. As the biomass on the disk builds up, excess slime is
sloughed off periodically and is removed in sedimentation tanks. The
rotation of the disk carries a thin film of waste water into the air
where it absorbs the oxygen necessary for the aerobic biological
activity of the biomass. The disk rotation also promotes thorough
mixing and contact between the biomass and the waste waters. In many
ways the RBC system is a compact version of a trickling filter. In the
trickling filter the waste waters flow over the media and thus over the
microbial flora; in the RBC system, the flora is passed through the
waste water.
The system can be staged to enhance overall waste water reduction.
Organisms on the disks selectively develop in each stage and are thus
particularly adapted to the composition of the waste in that stage. The
first couple of stages might be used for removal of dissolved organic
matter, while the latter stages might be adapted to nitrification of
ammonia.
D eve 1 opmen t ^ St a tus
The RBC system was developed independently in Europe and the United
States about 1955 for the treatment of domestic waste, but found
application only in Europe. Currently, there are an estimated 1000
domestic installations in Europe.21 However, the use of the RBC for the
treatment of meat packing waste is relatively new. The only operational
information available on its use on meat packing waste was obtained on a
pilot-scale system, although a large installation was recently completed
at the Iowa Beef Processors plant in Dakota City, Nebraska, for the
further treatment of meat packing waste effluents from an anaerobic
lagoon. The pilot-plant studies were conducted with a four-stage RBC
system with four-foot diameter disks. The system was treating a portion
of the effluent from the Austin, Minnesota, anaerobic contact plant used
to treat meat packing waste. These results showd a BOD5 removal in
excess of 50 percent with loadings less than 0.037 kg BODS on an average
BODS influent concentration of approximately 25 mg/1. Data from
Autotrol Corporaton revealed ammonia removals of greater than 90 percent
by nitrification in a multistage unit. Four to eight stages of disks
with maximum hydraulic loadings of 61 liters per day per square meter
(1.5 gallons per day per square foot) of disk area are considered normal
for ammonia removal.
88
-------
Advantages ^and^Disadyantaqes
The major advantages of the RBC system are its relatively low installed
cost; the effect of staging to obtain both dissolved organic matter
reduction and removal of ammonia nitrogen by nitrification; and its good
resistance to hydraulic shock loads. Disadvantages are that the system
should be housed, if located in cold climates, to maintain high removal
efficiencies, to control odors, and to minimize problems with
temperature sensitivity. Although this system has demonstrated its
durability and reliability when used on domestic wastes, it has not yet
been fully tested to treat meat packing plant wastes.
Uses
Rotating biological contactors could be used for the entire aerobic
secondary system. The number of stages required depends on the desired
degree of treatment and the influent strength. Typical applications of
the rotating biological contactor, however, may be for polishing the
effluent from anaerobic processes and from roughing trickling filters
and as pretreatment prior to discharging wastes to a municiapl system.
A BODS reduction of 98 percent is achievable with a four-stage RBC.2*
Performance^f Various Biological Treatment Systems
Table 6 shows BODS, suspended solids (SS), and grease removal
efficiencies for various biological treatment systems used to treat meat
packing waste waters. Average values are presented for ten systems;
exemplary values for five systems. Exemplary values each represent one
system (except for anaerobic plus aerobic lagoons, where they represent
two systems) considered to be among the best for that kind of system and
whose values were actually verified in the field sampling study con-
ducted during this program.
The number of systems used to calculate average values, also shown in
Table 6, clearly shows that the anaerobic plus aerobic lagoons are the
most commonly used. In fact this system was used by about 63 percent of
the plants included in the study that reported having secondary systems
(see Section VIII).
The estimated value of BODS shown for the anaerobic lagoons plus
rotating biological contactor is based upon pilot-plant results and is
considered to be conservative.
The values shown for the anaerobic lagoons plus extended aeration are
also estimated and are all below the values calculated by using average
removal efficiencies for the two components of the system individually.
For example, if the BODS reduction for both the anaerobic lagoon and
89
-------
extended aeration were 90 percent, the calculated efficiency of the two
systems combined would be 99.0 percent
Table 6. Performance of Various Secondary
Treatment Systems.
Secondary Treatment System
(number of systems used
to determine averages)
Anaerobic + Aerobic
lagoon (22)
Anaerobic + aerated +
Aerobic lagoon (3)
Anaerobic Contact Process +
Aerobic lagoon (1)
Extended Aeration +
Aerobic lagoon (1)
Anaerobic lagoon + Rotating
Biological contactor
Anaerobic lagoon + Extended
Aeration + Aerobic lagoon
Anaerobic lagoon +
Trickling filter (1)
2-Stage Trickling filter (1)
Aerated + Aerobic
lagoon (1)
Anaerobic Contact (1)
Water Wasteload Reduction
Average Values
BOD 5
95.4
98.3
93.5
96.0
98. 5e
98e
97.5
95.5
99.4
96.9
SS
93.5
93.3
96.0
86.0
—
93e
94.0
95.0
94.5
97.1
Grease
95.3
98.5
99.0
98.0
98e
96.0
98.0
—
95.8
Exemplary Values
BOD 5
98.9
99.5
96.0
99.4
96.9
SS
96.6
97.5
86.0
94.5
97.1
Grease
98.9
99.2
98.0
—
95.8
e - estimated
90
-------
TERTIARY AND ADVANCED^TREATMENT
Chemical Precipitation of Phosphorus
Phosphorus is an excellent nutrient for algae and thus can promote heavy
algae blooms. As such it cannot be discharged into receiving streams
and its concentration should not be allowed to build up in a recycle
water stream. However, the presence of phosphorus is particularly
useful in spray irrigation or land utilization systems as a nutrient for
plant growth.
The effectiveness of chemical precipitation. Figure 16, is well
established and has been verified in full scale during the North Star
verification sampling program. One packing plant operates a dissolved
air flotation system as a chemical precipitation unit and achieves a 95
percent phosphorus removal to a concentration of less than 1 mg/1.
Chemical precipitation can be used for primary (in-plant) treatment to
remove BOD5, suspended solids, and grease, as discussed earlier in
conjunction with dissolved air flotation. Also, it can be used as a
final treatment follcwing biological treatment, to remove suspended
solids in addition to phosphorus.
Technical^Description
Phosphorus occurs in waste water streams from packing plants primarily
as phosphate salts. Phosphates can be precipitated with trivalent iron
and trivalent aluminum salts. It can also be rapidly precipitated by
agglomeration of the precipitated colloids and by the settling rate of
the agglomerate.18 Laboratory investigation and experience with inplant
operations have substantially confirmed that phosphate removal is
dependent on pH and that this removal tends to be limited by the optimum
pH for the iron and aluminum precipitation occurs in the U to 6 range,
whereas the calcium precipitation occurs in the alkaline side at pH
values above 9.5.18 Coincident with the phosphate removal is the
efficient removal of suspended solids which are cleaned from the water
in the flocculant.
Since the removal of phosphorus is a two-step process involving
precipitation and then agglommerationr and both are sensitive to pH,
setting the pH level takes on added significance. if a chemical other
than lime is used in the precipitation-coagulation process, two levels
of pH are required. Precipitation occurs on the acid side and
coagulation is best carried out on the alkaline side. The precipitate
is removed by sedimentation or by dissolved air flotation.18
91
-------
Polyelectrolytes are polymers that can be used as primary coagulants,
flocculation aids, filter aids, or for sludge conditioning. Phosphorus
removal may be enhanced by the use of such polyelectrolytes by producing
a better floe than might occur without such chemical addition.23
The chemically precipitated sludge contains grease and organic matter in
addition to the phosphorus, if the system is used in primary treatment.
If it is used as a post-secondary treatment, the sludge volume will be
less and it will contain primarily phosphorus salts. The sludge from
either treatment can be landfilled without difficulty.
Float
or
Treatment
PH
Ajustment
X
Chemical
Addition
X
Air
Flotation
System
partial
x. ^fcptifii»tf
• • ^ icriiury
— I Treated
Sludge
to
Disposal
Figure 16. Chemical Precipitation
Development Status
This process is well-established and understood technically. Although
its use on meat industry waste is very limited, it is gaining acceptance
as a primary waste treatment process. Where it is in use, it is being
operated successfully if the process chemistry is understood and the
means to control the process are available.
Problems
92
-------
As indicated above, the reliability of this process is well established;
however, it is a chemical process and as such requires the appropriate
control and operating procedures. The problems that can be encountered
in operating this process are those caused by a lack of understanding or
inadequate equipment. Sludge disposal is not expected to be a problem.
The use of polyelectrolytes and their effect on the dewatering
properties of the sludge are open to some question at the present time.
Sand^Filter
A slow sand filter is a specially prepared bed of sand or other mineral
fines on which doses of waste water are intermittently applied and from
which effluent is removed by an under-drainage system, Figure 17; it
removes solids from the waste water stream. BOD5 removal occurs
primarily as a function of the degree of solids removal, although some
biological action occurs in the top inch or two of sand. Effluent from
the sand filter is of a high quality with BOD5 and suspended solids
concentrations of less than 10 mg/1.2* Although the performance of a
sand filter is well known and documented, it is not in common use
because it is not needed to reach current waste water standards.
A rapid sand filter functions as the slow sand filter but operation is
under pressure in a closed vessel or may be built in open concrete
tanks. It is primarily a water treatment device and thus would be used
as tertiary treatment, following secondary treatment. Mixed media
filters are special versions of rapid sand filters that permit deeper
bed-penetration by gradation of particle sizes in the bed. Up-^flow
filters are also special cases of rapid filters.
Chlorination,
Optional
Primary or
Secondary
Effluent
for Odor Control
v
Surface 0 Back
Clean Wash
to Regenerate
> Treated
Effluent
Figure 17. Sand Filter System
93
-------
Technical Description
The slow sand filter removes solids primarily at the surface of the
filter. The rapid sand filter is operated to allow a deeper penetration
bof suspended solids into the sand bed and thereby achieve solids
removal through a greater cross-section of the bed. The rate of
filtration of the rapid filter is up to 100 times that of the slow
filter. Thus, the rapid filter requires substantially less area than
the slow filter; however, the cycle time averages about 2U hours in
comparison with cycles of up to 30 to 60 days for a slow filter.25 The
larger area required for the latter means a higher first cost. For
small plants, the slow sand filter can be used as secondary treatment.
In larger sizes, the labor in maintaining and cleaning the surface may
operate against its use. The rapid sand filter on the other hand can be
used following secondary treatment, but would tend to clog quickly and
require frequent automatic backwashing if used as secondary treatment,
resulting in a high water use. This washwater would also need treatment
if the rapid sand filter is used following conventional solids removal.
The rapid filters operate essentially unattended with pressure-loss
control and piping installed for automatic backwashing. They may be
enclosed in concrete structures or in steel tanks.23
Clean-up of the rapid sand filter requires backwashing of the bed of
sand with a greater quantity of water than used for the slow sand
filter. Backwashing is an effective clean-up procedure and the only
constraint is to minimize the washwater required in clean-up as this
must be disposed of in some appropriate manner other than discharging it
to a stream.
Develop_ment__status
The slow sand filter has been in use for 50 years and more. It has been
particularly well suited to small cities and isolated treatment systems
serving hotels, motels, hospitals, etc., where treatment of low flow is
required and land and sand are available. Treatment in these applica-
tions has been a sanitary- or municipal-type raw waste. The Ohio
Environmental Protection Administration is a strong advocate of slow
sand filters as a secondary treatment for small meat plants, following
some form of settling or solids removal. As of early 1973, 16 sand
filters had been installed and 8 were proposed and expected to be
installed. All 24 of these installations were on waste from packing
plants.26 The land requirements for a slow sand filter are not
particularly significant in relation to those required for lagooning
purposes in secondary treatment processes. However, the quality and
quantity of sand is important and may be a constraint in the use of sand
filters in some local situations. It should also be recognized that
-------
this process requires hand labor for raking the crust that develops on
the surface. Frequency of raking may be weekly or monthly, depending
upon the degree of previous treatment and the gradation of the sand.
Problems
The reliability of the slow sand filter seems to be well established in
its long-term use as a municipal waste treatment system. When the sand
filter is operated intermittently there should be little danger of
operating mishap with resultant discharge of untreated effluent or poor
quality effluent. The need for bed cleaning becomes evident with the
reduction in quality of the effluent or in the increased cycle time,
both of which are subject to monitoring and control. Operation in cold
climates is possible as long as the appropriate adjustment in the
surface of the bed has been made to prevent blockage of the bed by
freezing water. Chlorination, both before and after sand filtering,
particularly in the use of rapid filters, may be desirable to minimize
or eliminate potential odor problems and slimes that may cause clogging.
The rapid sand filter has been used extensively in water treatment
plants and in municipal sewage treatment for tertiary treatment; thus
its use in tertiary treatment of secondary treated effluents from meat
plants appears to be a practical method of reducing BOD5 and suspended
solids to levels below those expected from conventional secondary
treatment.
Microscreen-Microstrainer
A microstrainer is a filtering device that uses a fine mesh screen on a
partially submerged rotating drum to remove suspended solids and thereby
reduce the BOD5 associated with those solids, Figure 18. The
microstrainer is used as a tertiary treatment following the removal of
most of the solids from the waste water stream. The suspended solids
and BODS can be reduced to 3 to 5 mg/1 in municipal systems. 19 There
are no reports of their use in the tertiary treatment of meat plant
wastes.
Secondary
Treotrnpnt ^
Effluent
Micro-
Screen
\
f
Ba<
skwash
Clear
to
Sere
ten/Strainer
Tertiary
Treated
Effluent
Figure 18. Microscreen/Microstrainer
95
-------
Technical Description
The microstrainer is a filtration device in which a stainless steel
microfabric is used as the filtering medium. The steel wire cloth is
mounted on the periphery of a drum which is rotated partially submerged
in the waste water. Backwash immediately follows the deposition of
solids on the fabric, and in one installation, this is followed by
ultraviolet light exposure to inhibit microbiological growth.*« The
backwash water containing the solids amounts to about 3 percent of the
waste water stream and must be disposed of by recycling to the
biological treatment system.28 The drum is rotated at a minimum of 0.7
and up to a maximum of 4.3 revolutions per minute.*9 The concentration
and percentage removal performance for microstrainers on suspended
solids and BODS appear to be approximately the same as for sand filters.
Deyelopment_Status
While there is general information available on the performance of
microstrainers and on tests involving the use of them, there appears to
be only one recorded installation of a microstrainer in use on municipal
waste; the requirements for effluent quality have not necessitated such
installation. The economic comparisons between sand filters and
microstrainers are inconclusive; the mechanical equipment required for
the microstrainer may be a greater factor than the land requirement for
the sand filter at the present time.
Problems and Reliability
The test performance of the microstrainer fairly well establishes the
reliability of the device in its ability to remove suspended solids and
the associated BOD?>. Operating and maintenance problems have not been
reported; this is probably because, in large part, of the limited use of
the device in full-scale applications. As a mechanical filtration
device requiring a drive system, it would have normal maintenance
requirements associated with that kind of mechanical equipment. As a
device based on microopenings in a fabric, it would be particularly
intolerant to any degree of grease loading.
Nitrificatign-Denitr^fication
This two-step process of nitrification and denitrification. Figure 19,
is a system to remove the nitrogen which appears as ammonia in treated
meat plant waste waters, and it is of ,primary importance for removal of
the ammonia generated in anaerobic secondary treatment systems. Ammonia
removal is becoming more important because of stream standards being set
96
-------
at levels as low as 1 to 2 mg/1.7 Removal of ammonia
complete, with the nitrogen gas as the end product.
is virtually
Technical Description
The large quantities of organic matter in raw waste from meat packing
plants is frequently and effectively treated in anaerobic lagoons. Much
of the nitrogen in the organic matter, present mainly as protein, is
converted to ammonia in anaerobic systems or in localized anaerobic
environments. The following sets of equations indicate the nitrifica-
tion of the ammonia to nitrites and nitrates, followed by the subsequent
denitrification to nitrogen and nitrous oxide.28 The responsible
organisms are indicated also.
rur nui
Secondary .
Treatment
Effluent
Aeration
System
>w
/
^ ^
Anaerobic
Pond
Aeration
Cell
Tertiary
> Treatea
Effluent
Carbon
Source,
e.g. Methanol
Figure 19. Nitrification/Denitrification
Nitrification:
NH3 + 02
N02- + H30+
(Ni tro somona s)
2NO2- +02
2N03-
(Nitrobacter)
Denitrification (using methanol as carbon source)
6H+ + 6NO_- + 5CH_OH 5CQ2 + 3N2 + 13 H20
Small amounts of N2O and NO are also formed
heterotrophs)
(Facultative
Nitrification does not occur to any great extent until most of the
carbonaceous material has been removed from the waste water stream. The
ammonia nitrification is carried out by aerating the effluent
97
-------
sufficiently long to assure the conversion of all the nitrogen in the
raw effluent to the nitrite-nitrate forms prior to the anaerobic
denitrification step.
The denitrification step, converting nitrates to nitrogen and nitrogen
oxides, takes place in the absence of oxygen. It is thought to proceed
too slowly without the addition of a biodegradable carbon source such as
sugar, ethyl alcohol, acetic acid, or methanol. Methanol is the least
expensive and performs satisfactorily. Investigators working on this
process have found that a 30 percent excess of methanol over the
stiochiometric amount is required.23,30
In current waste treatment practice using anaerobic and aerobic lagoons,
ammonia nitrogen that disappears in the aerobic system does not show up
to a large extent as nitrites and nitrates. Ammonia stripping is not
likely to account for the loss. It appears that denitrification must
actually be occurring in the bottom reaches of the aerobic lagoons,
where anaerobic conditions are probably approached.
Presuming total conversion of the ammonia to nitrites or nitrates, there
will be virtually no nitrogen remaining in the effluent from the de-
nitrification process. Total nitrogen removal can be maintained at 90
percent over the range of operating temperatures; the rate increases
with temperature to an optimum value of approximately 30°C for most
aerobic waste systems. Temperature increases beyond 30° result in a
decrease in the rate for the mesophilic organisms.28
The waste water is routed to a second aeration basin following de-
nitrification, where the nitrogen and nitrogen oxide are readily
stripped from the waste stream as gases. The sludge from each stage is
settled and recycled to preserve the organisms required for each step in
the process.
Development Status
The specific nitrification-denitrification process has been carried out
successfully at the bench- and pilot-scale levels. Gulp and Culp23
suggest that the "practicality of consistently maintaining the necessary
biological reactions and the related economics must be demonstrated on a
plantdeveloped at the Cincinnati Water Research Laboratory of the EPA
and is being built at Manassas, Virginia.31 This work and other
demonstrated useful concepts are reported in a recent EPA technical
booklet. *7 As mentioned above, observations of treatment lagoons for
meat packing plants gives some indication that the suggested reactions
are occurring in present systems. Also, Halvorson32 reported that
Pasveer ^.s achieving success in denitrif ication by carefully controlling
the reaction rate in an oxidation ditch, so that dissolved oxygen levels
drop to zero just before the water is reaerated by the next rotor.
98
-------
Problems and^Reliability
In view of the experimental status of this process, it would be pre-
mature to speculate on the reliability or problems incumbent in a full-
scale operation. It would appear that there would be not exceptional
maintenance or residual pollution problems associated with this process
in view of the mechanisms suggested for its implementation at this time.
Ammonia Stripping
Ammonia stripping is a modification of the simple aeration process for
removing gases in water. Figure 20. Following pH adjustment, the waste
water is fed to a packed tower and allowed to flow down through the
tower with a countercurrent air stream introduced at the bottom of the
tower flowing upward to strip the ammonia. Ammonia-nitrogen removals of
up to 98 percent and down to concentrations of less than 1 mg/1 have
been achieved in experimental ammonia stripping towers.23
Technical^Description
The pH of the waste water from a secondary treatment system is adjusted
to between 11 and 12 and the waste water is fed to a packed tower or to
a cooling tower type of stripping tower. As pH is shifted above 9 the
ammonia is present as the soluble gas in the waste water stream rather
than as the ammonium ion.30 Ammonia-nitrogen removal of 90 percent was
achieved with countercurrent air flows between 1.8 and 2.2 cubic meters
per liter (250 and 300 cubic feet per gallon) of waste water in an
experimental tower with hydraulic loadings between 100 and 125 liters
per minute per square meter (2.5 and 3 gallons per minute per square
foot). A maximum of 98 percent ammonia removal was reported with the
air rate at 5.9 cubic meters per liter (800 cubic feet per gallon) and a
hydraulic loading of 33 liters per minute per square meter (0.8 gallons
per minute per square foot). The ammonia concentration was reduced to
less than one part per million at 98 percent removal. The high
percentage removal of ammonia-nitrogen is achieved only at a substantial
cost in terms of air requirements and stripping tower cross sectional
area.23
Because the system involves the stripping of ammonia from a water
stream, ambient air temperatures below 0°C (32°F) present a problem;
operation in cold climates may require housing inside a building or
heating of the air prior to introducing it to the stripping tower. The
residual pollution would be the ammonia stripped from the waste water
stream and concentration of ammonia in the air stream prior to mixing
with the ambient_ air would be about 10 milligrams per cubic meter „
whereas the threshhold for odor is about 35 milligrams per cubic
meter.23
99
-------
Development Status
The ammonia stripping process is a well-established industrial practice
in the petroleum refinery industry. The only significant difference
between petroleum refinery application and that on a meat packing plant
waste would probably be the comparatively small size of stripping tower
for the meat packing plants in comparison to the refinery. The air
stripping of ammonia from secondary effluent is reported primarily on an
experimental basis in equipment that is 1.8 meters (6 feet) in diameter
with a packing depth of up to 7.3 meters (21 feet). Two large
Secondary
Treatment
Effluent
pH
Adjustment
Ammonia
Stripping
Tower
Air
Blowers
Treated
Effluent
Figure 20. Ammonia Stripping
scale installations of ammonia stripping of lime treated waste water are
reported at South Tahoe, California, and Windhoek, South Africa.23r118
The South Tahoe ammonia stripper was rated at iH.2 M liters per day
(3.75 MGD) and was essentially constructed as a cooling tower structure
rather than as a cylindrical steel tower which might be used in smaller
sized plants.
Thus, although there is no reported use of ammonia stripping on meat
packing plant waste, the technology is well established and implementa-
tion, when standards require it, should be without difficulty.
Problems and Reliabiility
The reliability of this process has been established by the petroleum
refinery uses of the process over many years. Although the source of
100
-------
the ammonia may be different and there may be other contaminants in the
water stream, none of this should affect the established reliability of
this process. The experience of other users of the process will have
pretty well identified potential problems, and, presumably, the
solutions for these problems. The maintenance requirements would be
only those normally associated with the mechanical equipment involved in
pumping the waste water to the top of the tower, where the feed is
introduced to the tower, and in maintaining the air blowers. The tower
fill would undoubtedly te designed for the kind of service involved in
treating a waste water stream that has some potential for fouling.
Spray/Flood Irrigation
A no discharge level for meat packing waste can be achieved by the use
of spray or flood irrigation of relatively flat land, surrounded by
dikes which prevent run-off and upon which a cover crop of grass or
other vegetation is maintained. Waste Water disposal is achieved by
this method to the level of no discharge. Specific plant situations may
preclude the installation of irrigation systems; however, where they are
feasible, serious consideration should be given to them.
Technical Description
Wastes are disposed of in spray or flood irrigation systems by dis-
tribution through piping and spray nozzles over relatively flat terrain
or by the pumping and disposal through the ridge and furrow irrigation
systems which allow a certain level of flooding on a given plot of land,
Figure 21. Pretreatment for removal of solids is advisable to prevent
plugging of the spray nozzles, or deposition in the furrows of a ridge-
and-furrow system, or collection of solids on the surface, which may
cause odor problems or clog the soil. Therefore, the BOD5 would
undoubtedly have already been reduced in the preliminary treatment in
preparation for distribution through the spray system.
In a flood irrigation system the waste loading in the effluent would be
limited by the waste loading tolerance of the particular crop being
grown on the land, or it may be limited by the soil conditions or
potential for vermin or odor problems.
101
-------
Waste Water distributed in either manner percolates through the soil and
the organic matter in the waste undergoes a biological degradation. The
liquid in the waste stream is either stored in the soil or leached to a
groundwater aquifer and discharges into the groundwater. Approximately
10 percent of the waste flow will be lost by evapotranspiration (the
loss caused by evaporation to the atmosphere through the leaves of
plants) . 28
Primary,
Secondary
or
Dnrtinl — — ^i
Tertiary
Treatment
Effluent
Holding
Basin
N-
Pumping
System
^
Application
Site
Grass or
Hay Crop
Figure 21. Spray/Flood Irrigation System
Spray runoff irrigation is an alternative technique which has been
tested on the waste from a small meat packer39 and on cannery waste.*0
With this technique, about 50 percent of the waste water applied to the
soil is allowed to run off as a discharge rather than no discharge as
discussed here. The runoff or discharge from this type of irrigation
system is of higher quality than the waste water as applied, with BOD5
removal of about 80 percent, total organic carbon and ammonia nitrogen
are about 85 percent reduced, and phosphorus is about 65 percent re-
duced. 39
The following factors will affect the ability of a particular land area
to absorb waste water: 1) character of the soil, 2) stratification of
the soil profile, 3) depth to groundwater, U) initial moisture content,
5) terrain and groundcover.28
The greatest concern in the use of irrigation as a disposal system is
the total dissolved solids content and particularly the salt content of
the waste water. A maximum salt content of 0.15 percent is suggested in
Eckenfelder.28 In order to achieve this level of salt content, 30
102
-------
percent of the total waste water stream from a typical plant was
determined to require treatment in an ion exchange system upstream from
the spray irrigation system.
An application rate of 330 liters per minute per hectare (35 gallons per
minute per acre) has been recommended in determining the quantity of
land required for various plant sizes. This amounts to almost 5 cm (2
inches) of moisture per day and is relatively low in comparison with
application rates reported by Eckenfelder for various spray irrigation
systems. However, soils vary widely in their percolation properties and
experimental irrigation of a small area is recommended before a complete
system is built. In many areas, rates as low as one-fourth inch per
acre per day are prerequisite for conservative, long term disposal
requirements.
The economic benefit from spray irrigation is estimated on the basis of
raising one crop of grass hay per season with a yield of 13.4 metric
tons of dry matter per hectare (six tons per acre) and values at $22 per
metric ton ($20 per ten). These figures are conservative in terms of
the number of crops and the price to be expected from a grass hay crop.
The supply and demand sensitivity as well as transportation problems for
moving the hay crop to a consumer all mitigate against any more
optimistic estimate of economic benefit.29
Cold climate uses of spray irrigation may be subject to more constraints
and greater land requirements than plants operating in more temperate
climates. However, a meat packer in Illinois reportedly operated an
irrrigation system successfully. Eckenfelder also reports that wastes
have been successfully disposed of by spray irrigation from a number of
other industries.
North Star found in its survey that the plants located in the arid
regions of the southwest were most inclined to use spray or flood
irrigation systems.
Problems and Reliability
Th long-term reliability of spray or flood irrigation systems is a
function of the ability of the soil to continue to accept the waste as
it is disposed of through the irrigation system, and thus reliability
remains somewhat open to question. Problems in maintenance are
primarily in the control of the proper dissolved solids level and
salinity content of the waste water stream and also in climatic
limitations that may exist or develop. Many soils are improved by spray
irrigation.
103
-------
Iont Exchange
Ion exchange, as a tertiary waste treatment, is used as a deionization
process in which specific ionic species are removed from the waste water
stream. Figure 22. Ion exchange would be used to remove salt (sodium
chloride) from waters. Ion exchange resin systems have been developed
to remove specific ionic species, to achieve maximum regeneration
operating efficiency, and to achieve a desired effluent quality. In
treating meat packing waste, the desired effluent quality is a total
waste water salt concentration of 300 mg/1. Ion exchange systems are
available that will remove up to 90 percent of the salt in a water
stream. 19 They can also be used to remove nitrogen.
Technical Description
The deionization of vater by means of ion exchange resin involves the
use of both cation and anion exchange resins in sequence or in
combination to remove an electrolyte such as salt. l9
RSO3 + NaCl* 9RSO3Na + NCI
R-OH + HC1 *R-C1 + H2O
where R represents the resin
The normal practice in deionization of water has been to make the first
pass through a strong acid column, cation exchange resin, in which the
first reaction above occurs. Effluent from the first column is passed
to a second column of anion exchange resin to remove the acid formed in
the first step, as indicated in the second reaction. As indicated in
the two reactions, the sodium chloride ions have been removed as ionic
species. A great variety of ion exchange resins have been developed
over the years for specific deionization objectives for various water
quality conditions.
104
-------
Waste Water treatment with ion exchange resins has been investigated and
attempted for over 40 years; however, recent process developments in the
treatment of secondary effluent have been particularly successful in
achieving high quality effluent at reasonable capital and operating
costs. One such process is a modification of the Rohm and Haas, Desal
process. 19 In this process a weak base ion exchange resin is converted
to the bicarbonate form and the secondary effluent is treated by the
resin to convert the inorganic salts. After the first step, the process
includes a flocculation/aeration and precipitation step to
sand filter and/or carbon adsorption system is used upstream of the
process is regenerated with aqueous ammonia and the cation resin with an
aqueous sulfuric acid. The resins did not appear to be susceptible to
fouling by the organic constituents of the secondary effluent used in
this experiment.
Partial
Tertiary
Treatment
Effluent
Tertiary
Treated
Effluent
Ion
Exchange
Column (s)
A
A
Backwash 8
Regenerant
System
Figure 22. Ion Exchange
Other types of resins can be used for nitrate and phosphate removal, as
well as color bodies, COD, and fine suspended matter. Removal of these
various constituents can range from 75 percent to 97 percent.
The cycle time on the ion exchange unit will be a function of the time
required to block or to take up the ion exchange sites available in the
resin contained in the system. Blockage occurs when the resin is fouled
by suspended matter and other contaminants. The ion exchange system is
105
-------
ideally located at the end of the waste water processing scheme, thus
having the highest quality effluent available as a feedwater. The ion
exchange system needed for irrigation purposes (mentioned earlier) based
on an assumed inlet salt concentration of 2000 mg/1, was required to
treat 30 percent of the waste water stream. This inlet concentration is
fairly conservative, based on the North Star survey data. Salt
concentration should be easily reduced to 1000 mg/1 and less with a
minimal effort at controlling salt discharge into the waste water.
To achieve a recyclable water quality, it may be assumed that less than
500 mg/1 of total dissolved solids would have to be achieved. Of the
total dissolved solids, 300 mg/1 of salt are assumed to be acceptable.
To achieve this final effluent quality, 95 percent of the waste water
stream would be subjected to ion exchange treatment.
The residual pollution will be that resulting from regeneration of the
ion exchange bed. The resin systems as indicated earlier, can be
tailored to the ion removal requirements and efficient use of
regeneration chemicals thus minimizing liquid wastes from the
regeneration step.
Development Status
Ion exchange as a unit operation is well established and commonly used
in a wide range of applications in water treatment and water
deionization. Water softening for boiler feed treatment and domestic
and commercial use is probably the most widespread use of ion exchange
in water treatment. Eeionization of water by ion exchange is used to
remove carbon dioxide; metal salts such as chlorides, sulfates,
nitrates, and phosphates; silica; and alkalinity. Specific resin
applications such as in wastewater treatment have not been widespread up
to the present time, as there has not been a need for such a level of
treatment. However, process development and experimental work have
shown the capability of ion exchange systems to achieve the levels of
salt removal required for the suggested irrigation and closed-loop water
recycle systems examined in this report.
Part of the economic success of an ion exchange system in treating
packing plant waste will probably depend on a high quality effluent
being available as a feed material. This again, can be provided by an
upstream treatment system including carbon adsorption or sand filtration
to remove a maximum of the particularly bothersome suspended organic
material. However, the affect of a low quality feed would be primarily
economic because of shorter cycle times, rather than a reduction in the
overall effectiveness of the ion exchange system in removing a specific
ionic species such as salt.
106
-------
Problems and Reliability
Inasmuch as ion exchange is widely used, the reliability of the concept
is well established. The application of the technology in waste
treatment has not been tested and therefore the reliability in that
application has yet to be firmly established. The problems associated
with ion exchange operations would primarily center on the quality of
the feed to the ion exchange system and its effect on the cycle time.
The operation and control of the deionization-regeneration cycle can be
totally automated, which would seem to be the desired approach.
Regeneration solution is used periodically to restore the ion exchange
resin to its original state for continued use. This solution must be
disposed of following its use and that may require special handling or
treatment. The relatively small quantity of regenerant solution will
facilitate its proper disposal by users of this system.
Carbon_Adsorption
Carbon adsorption is a unit operation in which activated carbon adsorbs
soluble and trace organic matter from waste water streams. Figure 23.
Either granular or powdered activated carbon can be used to remove up to
98 percent of colloidal and dissolved organics measured as BODS and COD
in a waste water stream. 30 The organic molecules which make up the
organic material attach themselves to the surface of the activated
carbon and are thereby removed. Larger particles should be filtered
from the waste water in treatment systems upstream from carbon
adsorption since the effectiveness of the latter will be substantially
reduced by gross particles of organic matter. Total organic carbon
removal efficiencies cf about 50 to 55 percent have been reported for
carbon adsorbers and 15 to 50 percent removal of soluble organic carbon
is reported, 118 Carbon adsorption treatment of meat packing waste would
be required only if a closed loop water recycle system were to be
installed with a requisite low organic concentration.
107
-------
Technical Description
Activated carbon in a granular or powdered form provides an active
surface for the attachment and resultant removal of organic molecules
from waste water streams. This is a surface adsorption phenomenon and
is not preferential for any particular molecule. Thus, in addition to
trace organic matter, odors and color bodies will also be removed from
the waste water stream by carbon adsorption. The rate of adsorption is
controlled by the rate of diffusion of the organic molecules within the
capillary pores of the carbon particles. This rate varies inversely
with the square of the particle diameter and increases with increasing
concentration of organic matter and with increasing temperature. The
implication of the particle diameter-adsorption rate relationship is
that the smaller the carbon particle the larger the adsorption rate will
be, in any given system. This factor is the basis for the interest in
powdered activated carbon in preference to granular carbon. «3
Partial Tertiary
Treatment -
Effluent
Adsorption
Column
Carbon
Regeneration and
Storage
Tertiary
Treated
Effluent
Figure 23. Carbon Adsorption
The granular carbon is effectively used in packed or expanded bed
adsorbers. A number cf processes have been experimentally attempted to
utilize powdered carbon in various process systems such as the fluidized
bed and carbon-tef fluent slurry systems. Regeneration of the carbon is
periodically required,. A standard regeneration technique is
incineration of the organic matter deposited on the surface of the
carbon. It is economically important to regenerate and recover the
carbon and regeneration has been a serious limitation to the use of
powdered activated carbon up to the present time.
108
-------
Carbon adsorption will remove up to about 98 percent of the colloidal
and dissolved organic matter with resulting effluent COD's down to 12
mg/1 in any of the various physical systems devised for contacting
activated carbon and waste water. This is a finishing treatment for
waste water intended to remove the trace organic material left after
standard secondary and partial tertiary treatment. Essentially all of
the gross organic particles must be removed from the waste water before
entering this treatment system, 23
The residual pollution associated with carbon adsorption will be that
caused by regeneration and a properly operated low oxygen furnace
achieving complete combustion of the organic matter should present no
pollution problem for the surrounding air environment.
Deye ^Lopment., Status
Activated carbon treatment in water purification is common practice and
well established. Several large scale pilot projects testing carbon
adsorption as a treatment of waste waters are presently underway. In
addition, carbon towers have been used for the removal of suspended
solids in a small number of municipal treatment systems requiring high
quality effluent. The treatment has not been applied specifically to
meat packing plant effluent; however, at the point in a waste treatment
system where an activated carbon system would be used, there should be
no significant difference between municipal waste and meat packing
waste. The effluent should be of high quality.
The primary question demanding the attention of research investigators
in the use of this system is to find an economic method for the use of
activated carbon in pcwdered form rather than granular form.
Problems and Reliabi1ities
Since this technology is well established in the water treatment
industry, it presumably can be operated with the proper type of
feedstream on an efficient and reliable basis. While the treatment of
waste water for this system is largely limited to large scale pilot
projects, the reliability and utility of such treatment should be
clearly established within a relatively short time, certainly before the
need for equipment to meet 1983 standards.
Operating and maintenance problems do not seem to be significant,
particularly if the quality of the feedwater is maintained by
appropriate upstream treatment systems. Regeneration is no problem in
the packed and expanded bed systems and presumably can be worked out for
powdered carbon systems before the mid 1980's.
109
-------
Reverse Osmosis
The reverse osmosis process uses semipermeable membranes to remove
contaminants dovm tc molecular size, Figure 24. It is capable of
removing divalent icns at efficiencies of up to 98 percent and
monovalent ions and small organic molecules at 70 to 90 percent. 33
Total solids concentrations between 25 mg/1 and 65 mg/1 have been
obtained in reverse osmosis effluent. 33 Reverse osmosis would not be
needed for applications other than a closed loop recycle water system.
The application of reverse osmosis to date has been limited to
capacities no larger than 190,000 liters (50,000 gallons) per day.
Technical Descriptjon
Several different kinds of semipermeable membranes are available for use
in the reverse osmosis process. Data are available on the use of
cellulose acetate membranes. These and other semipermeable membranes
are more permeable to pure water than to dissolved salt and other ions
and molecules. The process operates by reversing the normal osmotic
process by increasing the pressure on the side of the membrane
containing the contaminated water until pure water flows through the
membrane from the contaminated side to the pure water side. Excellent
rejection or removal of essentially all contaminants in a waste water
Partial
Tertiary
Treatment
Effluent
C\ >
AA *
Pressure
Pump
Reverse
Osmosis
System
»w
J
Full Tertiary
Treated
Effluent
Concentrated
Brine to
Disposal
Figure 24. Reverse Osmosis
110
-------
stream from a meat packing plant would be achieved through a reverse
osmosis system. However, the rate at which pure water would be produced
is still unacceptably low for economic application of this system.
Current development work is aimed at improving the rate at which pure
water can be produced, while retaining the high quality of the effluent.
Development Status
•'•• —I, 1^ L .
The application of reverse osmosis to the treatment of waste water
streams has been confined to experiments on domestic sewage on a small
scale. As a waste treatment process, the limited capacity of
commercially available units and the high operating costs tend to limit
the potential applicability of reverse osmosis waste water treatment in
the near future.
Problems^and Reliability
The reliability of reverse osmosis remains open to question until larger
scale and longer term experiments have been conducted on waste water
treatment. The two operating problems that persist in reverse osmosis
are maintaining flux cr water purification rates and the relatively
short operating life of the membranes. Another significant problem
remains in the bacterial growth that has been observed on reverse
osmosis membranes, which seriously reduces their operating efficiency.
Microbial growth has also been observed in the support structure under
the membranes. Chlorine cannot be used because the membranes which are
presently available are damaged by chlorination. i9 Research on these
operating problems is continuing, including membrane research at North
Star Research Institute, where new membranes are being developed and
tested. For example, a new North Star membrane, NS-1, which is formed
on the surface of a porous poly sulf one support material, is a
noncellulosic membrane which has significantly better operating
characteristics than irost membranes currently available.
Electrodialysis is a process that uses an applied electric current to
separate ionic species in a solution. Figure 25. Membranes allow
specific ions to pass from the waste water stream on one side of the
membrane to a highly concentrated solution of contaminants on the other
side of the membrane. Electrodialysis is used to remove dissolved
solids such as salt, which is of particular concern in meat industry
waste. Single-pass removal efficiencies of up to UO percent of the salt
are the reported performance of the system. 30
111
-------
Technical Description
The electro-dialysis process incorporates a number of chambers made by
alternating anionic and cationic membranes that are arranged between two
electrodes. A brine solution is alternated with contaminated waste
water solution in the chambers between the differing membranes.
Electric current is applied across the membrane chambers causing the
cations to move towards the cathode and the anions towards the anode.
However, after passing from the chambers containing the waste water into
adjacent brine chambers, the ions can travel no further toward the
electrodes. Their path is blocked by a membrane that is impermeable to
that particular ionic species. In this manner, the waste water stream
is depleted while the adjacent brine stream is enriched in the ions
which are to be removed.
Power costs limit the salinity of the effluent waste water after
treatment in the electrodialysis system to approximately 300 to 500 mg/1
of salt. 34 This limitation is imposed because of the increase in
electrical resistance in the treated waste water that would occur at
lower concentrations of salt.
Partial
Tertiary ^
Treatment
Effluent
Electro -
dialysis
System
\
f
Full Tertiary
Treated
Effluent
Concentrated
Brine to
Disposal
Figure 25. Electrodialysis
Development Status
The residual pollution from an electrodialysis unit would be the brine
solution used and generated in the chambers of the unit. This brine
solution might be handled by a blowdown system which removes the
quantity of salt added per unit of time. Electrodialysis is an old
112
-------
process and in fairly widespread use for the purpose of desalting
brackish water, 34 The treatment of waste water in electrodialysis
systems has not been done except on an experimental basis. There is no
reported application of the process on waste water from the meat
industry which tends to have a fairly substantial salt content. The
potential utility of the process is therefore speculative as to its use
on waste water, however, its widespread use in water desalting suggests
that, if the need arises for its application, it is technically feasible
to desalt waste water in such a process.
Problems and^Reliabjlity
The reliability of the electrodialysis system in removing salt from
waste waters is only speculative based on the use of the system in
desalting brackish waters. It has demonstrated its reliability in the
desalting application. The problems associated with using this process
in treating waste water from meat packing plants is the substantial
cost, the necessity cf brine disposal, and the bacterial growth which
occurs on the dialysis membranes, *8 Chlorine cannot be applied because
it damages the membranes.
113
-------
SECTION VIII
COST, ENEFGY, AND NON^WATER QUALITY ASPECTS
Summary.
The waste water from meat packing plants is amenable to treatment in
secondary and tertiary v/aste treatment systems to achieve low levels of
pollutants in the final effluent. In-plant controls, by-product
recovery operations, and strict water management practices can be highly
effective in reducing the wasteload and waste water flow from any
industry plant. These water management practices will reduce the
requisite size of secondary and tertiary treatment systems and improve
their waste reduction effectiveness.
The waste treatment investment for a typical plant in each industry
sufccategory is listed in Table 7 to achieve each of four successively
increased degrees of treatment:
A - reduction of organics by the use of anaerobic plus aerated
plus aerobic lagoon treatment systems,
B - in-plant controls plus partial tertiary treatment.
C - no discharge via land disposal by irrigation.
D - waste water recycle.
The costs reported in Table 7 are based on the assumption that the
average plant in each subcategory has anaerobic plus aerobic waste
treatment lagoons or the equivalent, already installed. The costs are
therefore the total incremental investment costs required to go to each
stage from the present treatment systems, described above. These costs
are primarily a function of total waste water flow. The average daily
flow used for each sutcategory is as follows:
Simple slaughterhouse - 1.17 M liters/day (0.310 MGD)
Complex slaughterhouse - 4.35 M liters/day (1.16 MGD)
Low-Processing packinghouse - 3.4 M liters/day (0.85 MGD)
High-Processing packinghouse - 4.4 M liters/day (1.2 MGD)
Treatment "A" comprises the three lagoon treatment system—anaerobic-
aerated-aerobic lagocns—or its equivalent as the means to achieve the
reduction of the organic load to the 1977 guideline. The typical plant
in each of the four industry subcategories has adequate in-plant
facilities-usually a catch basin—to preclude the need for in-plant
additions in stage "A".
Treatment "B" incorporates improved in-plant practices and the addition
of a dissolved air flotation unit along with an ammonia removal step and
sand filtering, or the equivalent, in addition to treatment system "A".
These treatment systems are applicable to plants in any of the
subcategories. The organic loading and total waste water flow will vary
115
-------
both within and between subcategories; however, these factors influence
treatment system sizing rather than applicability, as indicated in
Section IV.
Treatment "C" is the irrigation alternative and includes the treatment
achieved in "A", plus dissolved air flotation, ion exchange on a part of
the waste water stream, chlorination, and the irrigation system. Total
dissolved solids are a limiting factor in water for irrigation; thus
plants in the "high-*processing packinghouses" subcategory, which exhibit
a high average chloride content in the raw waste (Chapter 5) may need to
devote special attention to it.
Treatment "D" comprises all of the treatment techniques presumably
required to produce a recyclable waste water stream of potable quality.
These technologies can be used by all of the subcategories if they are
effective for any one of them.
Table 7. Total Investment Costs Per Plant for Upgrading Present
Waste Treatment System to Each Stage of Treatment
Effluent
Quality
A
B
C
D
Simple
Slaughterhouse
$ 80,000
425,000
268,000
733,000
Complex
Slaughterhouse
$ 139,000
665,000
487,000
1,315,000
Low-Processing
Packinghouse
$ 131,000
629,000
451,000
1,227,000
High-Processing
Packinghouse
$ 148,000
736,000
544,000
1,475,000
*Locker plants were,not included in any subcategory, but were assumed to require an
investment of $10,000 each to go to no discharge by 1977, which appears to be the
most attractive choice other than municipal treatment.
116
-------
The annual operating costs for a treatment system to achieve the
indicated effluent quality are reported in Table 9. The costs to
achieve treatment level "A" range from 12 to 21 cents per head of beef,
depending on the sutcategory. The costs to achieve treatment level "B"
vary from $0.90 to $1.50 per head more than present waste treatment
costs. Costs above present for level "C" are about two-thirds of those
for level "B", and costs for level D are nearly twice those for level
"B".
Energy consumption associated with waste water treatment in the meat
industry is not a serious constraint, varying from 10 to 40 percent of
present power consumption. The higher percentage is for the smaller
packing plants that consume relatively small quantities of electric
energy at the present time.
With the implementation of these standards, land becomes the primary
waste sink instead of air and water. The waste to be land filled from
packing plants can improve soils with nutrients and soil conditioners
contained in the waste. Odor problems can be avoided or controlled in
all treatment systems.
"TYPICAL" PLANT
The waste treatment systems applicable to waste water from the meat
packing industry can te used by plants in all four subcategories of the
industry, A hypothetical "typical" plant was constructed in each
subcategory as a basis for estimating investment and total annual costs
for the application of each waste treatment system within each
subcategory. The costs were estimated, and, in addition, effluent
reduction, energy requirements, and non^water quality aspects of the
treatment systems were determined.
117
-------
The waste treatment systems are applied on the basis of the following
plant configurations for each subcategory:
Industry Subcategory \
Kill, kg LWK/day
(Ib LWK/day)
Waste Water flow
liters/1000 kg LWK
(gal/1000 Ib LWK)
Raw waste, BODS
kg/1000 kg LWK
(lb/1000 Ib LWK)
Processed meat
production
kg/day
(Ib/day)
Simple
Slaughter-
house
220,000
(484,000)
5,328
(639)
6.0
(6.0)
0
Complex
Slaughter-
house
595,000
(1,310,000)
7,379
(885)
10.9
(10.9)
0
Low-
Processing
Packing-
house
435,000
(900,000)
7,842
(941)
8.1
(8.1)
54,000
(119,000)
High-
Processing
Packing-
house
350,000
(800,000)
12,514
(1,500)
16.1
(16.1)
191,000
(422,000)
basis of responses to the North Star questionnaire as follows:
Plant
Small
Medium
Large
TOTAL
Simple
65.456
33.9
0.7
100.0
Complex
0%
50
50
100.0
Low- Process ing High-Processing
63. OX
27.2
9.8
100.0
0%
17.3
82.7
100.0
Total
50.4*
39.0
10.6
100.0
Locker plants are not included in this tabulation.
kill are related as fellows:
Small - less than 11.4 MM kgs/year (25 MM Ib)
Medium - 11.4 to 91 MM kg/year (25-200 MM Ib)
Large -» greater than 91 MM kg/year (200 MM Ib)
Plant size and annual
118
-------
Table 8. Estimated Total Investment Cost
to the Industry to Achieve a Given
Level of Effluent Quality from
Present Level of Treatment
Effluent
Quality
A
B
C
D
Total Industry
Investment ,
($ millions)
52.8*
159.7
119.0
252.2
Investment
Cost per
million kg LWK
per year
2,355
7,119
5,306
11,240
Investment
Cost per
million Ib LWK
per year,
1,069
3,232
2,409
5,103
*Includes $10,000 per plant for 2600 locker plants, totaling $26 million.
Table 9. Total Increase in Annual Cost of Waste Treatment,
$/1000 kg ($/1000 Ib) LWK.
Effluent
Quality
A
B
C
D
Simple
Slaughterhouse
0.35
(0.16)
2.93
(1.33)
2.00
(0.91)
4.74
(2.15)
Complex
Slaughterhouse
0.26
(0.12)
1.92
(0.87)
1.34
(0.61)
3.17
(1.44)
Low-Processing
Packinghouse
0.33
(0.15)
2.44
(1.11)
1.74
(0.79)
4.30
(1.95)
High-Pr o c es s ing
Packinghouse
0.46
(0.21)
3.37
(1.53)
2.42
(1.10)
5.62
(2.55)
119
-------
Table 10. Waste Treatment Systems, Their Use
and Effectiveness
Treatment
System
Use
Effluent Reduction
Dissolved air flotation
(DAF)
DAF with pH control and
flocculants added
Anaerobic + aerobic
lagoons
Anaerobic + aerated +
aerobic lagoons
Anaerobic contact
process
Activated sludge
Extended aeration
Anaerobic lagoons +
rotating biological
contactor
Chlorination
Sand filter,
Microstrainer
Electrodialysis
Ion exchange
Ammonia stripping
Carbon adsorption
Chemical precipitation
Reverse osmosis
Spray irrigation
Flood irrigation
Ponding and evaporation
Primary treatment
or by-product
recovery
Primary treatment
or by-product
recovery
Secondary treatment
Secondary treatment
Secondary treatment
Secondary treatment
Secondary treatment
Secondary treatment
Finish and
disinfection
Tertiary treatment &
Secondary treatment
Tertiary treatment
Tertiary treatment
Tertiary treatment
Tertiary treatment
Tertiary treatment
Tertiary treatment
Tertiary treatment
No discharge
No discharge
No discharge
Grease, 60% removal, to
100 to 200 mg/1
BOD5, 30% removal
SS, 30% removal
Grease, 95-99% removal,
BOD5, 90% removal
SS, 98% removal
BOD , 95% removal
BOD , to 99% removal
BOD , 90-95% removal
BOD , 90-95% removal
BOD , 95% removal
BOD , 90-95% removal
BOD5, to 5-10 mg/1
SS, to 3-8 mg/1
BOD5, to 10-20 mg/1
SS, to 10-15 mg/1
TDS, 90% removal
Salt, 90% removal
90-95% removal
6005, to 98% removal as
colloidal & dissolved
organic
Phosphorus, 85-95% removal
to 0.5 mg/1 or less
Salt, to 5 mg/1
TDS, to 20 mg/1
Total
Total
Total
120
-------
WASTE TREATMENT SYSTEMS
The waste treatment systems included in this report as appropriate for
use on meat packing plant waste water streams can be used by all plants
in the industry. The treatment systems will work, subject to specific
operating constraints or limitations. However, the cost of such
treatment systems may be uneconomical or beyond the economic capability
of some plants.
The waste treatment systems, their use, and the minimum effluent
reduction associated with each are listed in Table 10. The dissolved
air flotation system can be used upstream of any secondary treatment
system. When operated without chemicals, the by-product grease
recovered in the floe skimmings has an economic value estimated at
112/kg (52/lb). The use of chemicals will increase the quantity of
grease removed from the waste water stream, but may reduce the value of
the grease because of the chemical contaminants.
Elementary biological treatment systems generally require more land than
Mechanically assisted systems which in turn increase the energy
consumption and cost of equipment in achieving comparable levels of
waste reduction. Some of the tertiary systems are interchangeable. Any
of them can be used at the end of any of the secondary treatment systems
to achieve a required effluent quality. Chlorination is included if a
disinfection treatment is required. A final clarifier has been included
in costing out all tiological treatment systems that generate a
substantial sludge volume; e. g,, extended aeration and activated
sludge. The clarifier is need to reduce the solids content of the final
effluent.
The most feasible system for no discharge at this time is flood or spray
irrigation, or, in some cases, evaporation from a shallow pond, closing
the loop to a total water recycle or reuse system is technically
feasible, but costly. The irrigation option does require large plots of
accessible land—roughly 2.7 hectares/million liters (25 acres/million
gallons) of waste water per day; and limited concentrations of dissolved
solids. More detailed descriptions of each treatment system and its
effectiveness are presented in Section Vll-Control and Treatment
Technology.
Of all the plants in the study sample that reported waste water
treatment, 55 percent indicated discharging raw waste to a municipal
treatment system. Thirty-eight plants reported some on-site secondary
treatment. Of the 38 plants, 63 percent used the anaerobic plus aerobic
lagoons system. This system was used to treat large and small waste-
water streams alike, varying from 76,000 liters per day (0.2 MGD) to 4.8
million liters per day (1.3 MGD). The rest of the systems listed as
secondary treatment were used by 1, 2, or 3 plants each, except the
121
-------
rotating biological contractor, which is now being evaluated at full-
scale at one site.
Dissolved air flotation is used as a primary treatment, either alone or
along with screens or a catch basin, by about 30 percent of the plants
in the sample. About 5 percent use chemicals in the flotation system.
Chlorination is a rare practice, according to the information collected
in the survey questionnaires; it appears to be used by about 5 percent
of the plants.
Other than sand filters and spray irrigation, there is no reported use
of any of the advanced treatment systems. Sand filters are used for
secondary treatment in Ohio instead of anaerobic lagoons, which are
discouraged by the Ohio Environmental Protection Administration. The
few spray irrigation systems are located in arid regions of the
Southwestern U.S.
Among the industry subcategories, for which we have specific plant
information, slaughterhouses have almost twice as many air flotation
systems in use as do packinghouses. Municipal treatment and the
anaerobic plus aerobic system for secondary treatment are used by the
bulk of the industry, A breakdown of the sample by subcategory is as
follows:
Secondary Treatment by Each Subcategory, %
Municipal
treatment , %
Anaerobic +
aerobic
lagoons, %
Other, %
TOTAL
Simple
Slaughter-
house
56
33
11
100%
Complex
Slaughter-
house
29
65
6
100%
Low-
Processing
Packing-
house
70
11
19
100%
High-
Processing
Packing-
house
59
14
27
100%
North Star
Sample of
Industry
55
28
17
100%
The complex slaughterhouses have an unusually low percentage using
municipal treatment in comparison with the other three subcategories.
The plants in this subcategory are typically the large-scale
slaughterhouses and they tend to be located close to the animal supply
rather than in cities, thus often precluding municipal treatment. This
tabulation does not take into account the large number of small plants
in the industry. Depending on the source of information, the total
122
-------
number of plants in the industry varies from 4000 to 6000 and the
approximate percentage of small plants varies from 85 to 90 percent.
However, these small plants account for only 10 percent or less of the
industry's output and, probably, a somewhat smaller proportion of the
total waste water load. Of the few small plants for which data were
available, about 50 percent reported discharging waste water into city
sewers. The remaining 50 percent used a wide variety of secondary
treatment systems. Based on all of the available information, it is
estimated that 50 percent of the small plants use municipal treatment
facilities, a small percent probably dump raw waste into local streams
or use land disposal, and the remaining plants treat their own waste.
Taken as single point sources of waste water, these small plants
represent an unknown but a very small fraction of the total wasteload on
receiving streams.
123
-------
TREATMENT AND CONTROL COSTS
In-Plant^Cgntrol ..Cost s
The cost of installation of in-plant controls is primarily a function of
the specific plant situation. Building layout and construction design
will largely dictate what can be done, how, and at what cost in regard
to in-plant waste control techniques. No in-plant control costs were
included in the cost estimates for Level 1 and 2 technologies, although
a dissolved air flotation system as primary treatment was included in
the Level 2 costs. Rough approximations of the range of costs for the
in-plant controls requiring capital equipment are listed in Table 11.
Table 11. In-Plant Control Equipment Cost Estimates
Plant Area
Item
Equipment Cost Range
Pen wastes
Blood handling
Paunch handling
Viscera handling
Troughs
Rendering
Hide processing
Hog Scald Tank
Pickle & Curing
solutions
Water Conservation
Water Conservation
Roof on pens
Manure sewer
Curbing & collection
system
Blood dryer
Solids pumping
system
Liquid screening &
collection equip-
ment
Localized catch basin
Surface condensers
Tankwater evaporator
Overflow collection
& treatment
Water treatment &
reuse system
Solution collection,
treatment, reuse
system
Install spray nozzles
Press-to-open &
foot operated valves
$5000 - $10,000
$8 - $12/foot
$10,000 - $50,000
$30,000 - $50,000
$10,000 - $20,000
$5,000 - $10,000
$6,000 - $12,000
$5 - $10/foot
$15,000 - $20,000
$50,000 - $200,000
$5,000 - $20,000
$10,000 - $25,000
$10,000 - $30,000
$5,000 - $10,000
$10,000 - $20,000
-------
Secondary and Tertiary Treatment Costs
The total investment cost and annual cost expressed in 0/100 kg LWK
(2/100 Ib LWK) are reported by subcategory for each secondary treatment
system, air flotation, and chlorination in Table 12. These costs are
listed on the same basis for each tertiary or advanced treatment system
in Table 13.
The annual costs of secondary treatment for all categories vary from 6.0
to 17.8 0/100 kg LWK (2.7 to 8.1 0/100 Ib LWK), excluding the highest
figures. The 10-year (1962-1971) average earnings reported by the
American Meat Institute are 750/100 kd (340/100 Ib) LWK, These
estimated annual costs of waste treatment, which are very conservative
from an accounting viewpoint, represent between 8 and 24 percent of the
10-year average earnings, Presuming an acceptable recycle water quality
can be achieved throuuh advanced waste treatment, including ammonia
stripping, ion exchange, carbon adsorption, and chemical precipitation,
the total estimated investment would vary from $700,000 to $1.6 million,
including secondary treatment costs. The annual costs would range from
26 to 550/100 kg LWK (12 to 250/100 Ib LWK), or about 35 to 74 percent
of the lOyear average earnings.
No discharge could be achieved by a spray irrigation system, incor-
porating partial treatment by ion exchange to reduce dissolved solids,
and would result in tctal costs between $270,000 and $544,000 and annual
costs between 13 and 240/100 kg LWK (6 and 110/100 Ib LWK) .
The waste treatment system costs are based on the kill, waste water flow
and BODjj figures listed previously for a "typical", but hypothetical,
plant in each subcategory. Investment costs for specific waste
treatment systems are largely dependent on the waste water flow. Some
of the lagoon systems are designed on BOD5 loading, which has been shown
to increase with increased water use.
In averaging the waste water flow for each subcategory, it was found
that one standard deviation for three subcategories was 100 percent of
the average water flow, and 75 percent of the average for the other
subcategory. The capacity-cost relationships of the biological
treatment systems tend to flatten out as the capacity approaches 3.785
million liters (1 million gallons) per day. Thus, the investment cost
of treatment facilities will not change substantially with small changes
in water use, and interpolation or extrapolation of investment cost for
different capacities is best made by the use of graphical presentation
and analysis of the data. However, the capacity-cost relationships of
125
-------
CN
rH
43
Cd
H
00
C 01
•H CO
01 3
CD O
01 43
CJ OO
0 G
V4 'rl
pi j ^
1 CJ
43 n)
00 Pu
•H
as
00
c o)
•H 0)
01 3
01 O
01 43
U 00
o a
r4 -H
p , K>{
1 U
O PL.
t •]
0)
co
3
0
oi OJ
rH 4-1
roo
3
o cd
rH
C/3
OI
0}
3
O
(11 43
fell
4J
43
00 00
3
cd
rH
OO
rH
3
G
C
•fl!
H
4J
O
H
rH
cd
C
^c
rH
cd
0
H
H
3
rJ
rj
«jj
, — |
cd
4-1
o
H
rH
a
rt
c
M
4-1
O
4-1
C
01
e
4-1
01
0)
>
G
M
4-1
01
0
O
4-1
§
8
4-1
co
01
>
(3
M
01
o
c_>
4-1
Ci
(U
0
4-1
10
0).
>
13
M
S
5J
4-1
U)
X
oo
I*** co cj» •<}•
O CD O CD
°*-s *^f
CN
B
VO rH
OO CM
cTi -^ r-~ co
O O O O
'•^s x— '
in
•
a> r-
•* CM ~* CM
O o o O
x— / ^^
oo
•
H 00
00 rH
^^» *«3" s~\
-* rH 4J C CO
M 43 rH 1 -H -H
4-1 to O 0) M C
I -H CO M O vH
01 G CO O. rH MH
l-i -H -H 43
PL, fn Q U
*-3" Is*" ^3 00
^D d~ r^* cy» co
O ^d-
x— '
00
cr>
CO
m ?
r>- co
^-^
CN
CO
^J-
v£) OO
O -*
i — 1 N->
O
H
CN
CJ
•rl
43
O
M
01
td
T3
01
4J
cd
M
4!
vD
CN
rH
0
in
^
o\
o
o
tn
CO
r~-
o
CM
in
CO
xD
rH
O
H
4-1
O
cd
4-1
a
0
o
CJ
•H
43
O
M
01
cd
P
m
^ — '
CJ
.3-
N— '
CO
CO
^-^
<*
^
^-s
to
01
01
CJ
o
M
p<
rH CO
r-* CM
CM rH
^ — '
m
r~-
co
rH
00 r7
r^ oo
i — I ^-^
O
o
o
rH
co m
-3- VD
rH ^ — '
0
CO
i-H
H
CM OO
r^ r^
i-H *-*
00
*^-
0)
00
T)
3
rH
CO
XI
01
4J
cd
>
•rl
4J
O
CN O
CO vD
1 — 1 *^^
CO
r-%
CO
rH xD
O
^o
CO
xO C7t
OO CO
^ — f
O
co
co in
*3" VO
i x,^
OO
o
CO
G
+ 0
•H
G 4J
o cd
O t-l
00 OJ
cd cd
H
T3
a cu
•H T3
43 G
o oi
M 4-1
OJ X
cd oi
+
G
O
o
00
P-j
CJ
•H
43
O
01
cd
xO OO
CD
^~
\^
CO
vD OO
CD -*
00
rH
i — 1
cd
u
•H
Ml
O
rH
O
•H
M
00 O
(3 4-1
•H CJ
4-1 Cd
Cd 4J
4-1 G
O O
M CJ
126
-------
rH
60
o
o
en t-H
4-J \
CO O
o
u •>
(0
4-) O
cd
4-1 3
C C
0) C
cd •*>
a) o
»H O
a) > /-s
4-1 fai
CO •> ^
Cd 4-1 nJ
S C
0) ,£>
13 B rH
01 4-J
O CO O
C H
> C -^
T3 M O
cd
H
isn
G
•H 0)
CO CO
CO 3
CU O
CJ x:
O 60
M C
PH -H
X! O
00 Ed
•rl PH
K
C V
•H CO
CO 3
CO O
cu xl
0 60
0 C
M 'H
PH. . i
( CJ
3 cd
0 PH
ij
CO
3
Kri
Q) M
rH 01
dt 4-1
0 X!
O 60
0 3
cd
rH
C/J
CU
CO
3
O
CU Xi
rH VH
PU CU
•rl X*
C/3 60
3
cd
rH
cn
rH
Cd 4-J
3 co
C 0
^
w
G
cu
tH B
Cd 4-1
4-1 CO
O 0)
H >
G
M
, — |
Cd 4-J
3 co
G 0
G cj
<3
4-1
G
cu
•H B
Cd 4-1
4-1 CO
O CU
H >
G
M
Cd 4-1
C 0
<3
4-1
G
CU
H B
Cd 4J
4J CO
O CU
H >
G
M
Cd 4-1
3 co
G 0
G 0
C
rH
4-1
G
cu
B
cd
0)
M
H
0) §
4-1 4-1
CO CO
cd >>
tS C/)
/ — \ f — V s~^
OO CN CO -3- CM O
-* CM LO CN VO rH
'— ' -— ' CN \D CO CO * CN| i — I
v^ s
O IO O
O C"O
LO rH i — | , — | -*
00 -v!"
o
•H
4-1
•H
p.
•H
O
PU
i-H
cd
•rl
CU
rj
u
coC?
LO CM
— '
r —
CTv
CM
O 00
~* rH
\^s
o^
CM
CN
rH 5
CO rH
>^J-
IO
CM
CM cn
-* rH
^/
rH
CJ\
C
•H
4-1
•H
M
•H
K^l
cd
ij
p
w
127
-------
the advanced treatment systems are more similar to those of a typical
process industry, with a capacity ratio exponent between 0.6 and 0.8,
and cost estimates may be made using the exponential approach. Because
of industry variability and cost estimating approximation, specific
plants within each sutcategory will incur waste treatment investment
costs which will differ from those reported for each subcategory by as
much as 50 to 100 percent, and perhaps more.
The investment cost data were collected from the literature, personal
plant visits, equipment manufacturers, engineering contractors, and
consultants. These costs are "ball-park" type estimates implying an
accuracy of + 20 to 25 percent. Rarely is it minus. All costs are
reported in August 1971 dollars. Percentage factors were added to the
basic system estimate for design and engineering (10%) and for con-
tingencies and omissions (15%). Land costs were estimated to be $2470
per hectare ($1000 per acre) .
In addition to the variation in plant water flows and BODS loadings and
the inherent inaccuracy in cost estimating, one additional factor
further limits the probability of obtaining precise cost estimates for
waste treatment systems. This factor was reported by a number of
informed sources who indicated that municipal treatment systems will
cost up to 50 percent more than comparable industrial installations.
The literature usually makes no distinction between municipal and
industrial installation in reporting investment costs,
Annual Costs Assumptions
The components of annual costs include capital cost, depreciation,
operating and maintenance costs, and energy and power costs. The cost
of capital is estimated to be ten percent of the investment cost for the
meat packing industry. This cost should be a weighted average of the
cost of equity and of debt financing throughout the industry. Neither
individual companies nor industry associations have a known figure for
this cost. Presuming that target and realized return-on-investment
(ROI) or return-on-assets (ROA) figures incorporate some estimate of
capital cost plus an acceptable profit or return, industry and corporate
reports were used as a guide in selecting the 10 percent figure. One
sample of companies reported earnings at 7.1 percent of total assets for
1971, 35 a recent business periodical reported earnings at 10.1 percent
of invested capital, 36 and general industry sources report corporate
target ROI or ROA figures at 12 to 15 percent for new ventures. The ten
percent figure is probably conservative and thus tends to result in a
high estimate of annual cost.
The depreciation component of annual cost was estimated on a straight^
line basis over the following lifetimes, with no salvage value:
128
-------
Land costs — not depreciated
Cost of improvements for land intensive treatment — 25 years
Simple treatment systems without complex process equipment:
e.g., extended aeration, sand filter — 25 years
Treatment systems requiring complex process equipment -- 10 years
The operating and maintenance costs include the cost of one man-year at
$4.20/hr for each typical secondary treatment system plus 50 percent for
burden, supervision, etc. One-half man-year was included in the If a
licensed
treatment plant operator is assumed, an additional annual cost
of $5000. would be reflected in operating costs. annual cost for each
tertiary treatment plus the 50 percent burden, etc. General and
maintenance supplies, taxes, insurance, and miscellaneous operating
costs were estimated as 5 percent of the total investment cost per year
for process equipment based systems and 2.5 percent of the total
investment cost for land intensive waste treatment systems. Specific
chemical-use costs were added when such materials were consumed in the
waste treatment system. By-product income, relative to waste treatment
was credited only in the dissolved air flotation system for 160 mg/1 of
grease recovered per day and sold at $0.05 per pound, and in spray
irrigation for 13,400 kg of dry matter (hay or grass) per hectare at
$22/100 kg (6 tons/acre at $20/ton) and one crop per season.
ENERGY_REOJJIRJEMENTS
The estimated electrical energy consumption per plant based on 1967
Census of Manufacturers 37 data is as follows:
Small plants -- 0.72 million KWH per year
Medium plants —r 5.5 million KWH per year
Large plants -- 18.6 million KWH per year
The meat packing industry consumes relatively small quantities of
energy. The waste treatment systems require power primarily for pumping
and aeration. The aeration horsepower is a function of the wasteload
and that for pumping depends on waste water flow rate.
Power consumption for waste treatment varies from 0.8 to 3.4 million KWH
per year for various secondary treatment systems. This consumption is
between 10 and 40 percent of that indicated above for 1973. The larger
plants with greater power consumption would tend toward the smaller per-
centage. The total additional power consumption to achieve Level 1 and
129
-------
Level 2 does not appear to raise serious power supply or cost questions
for the meat packing industry.
Thermal energy costs roughly equal electrical energy costs for
operations within the industry. Waste treatment systems impose no
significant addition to the thermal energy requirements of plants.
Waste Water can be reused in cooling and condensing service if it is
separated from the process waters in surface condensers. These heated
wastewaters improve the effectiveness of anaerobic ponds which are best
maintained at 90°F or more. Improved thermal efficiencies are
coincidentally achieved within a plant with this technique.
Waste Water treatment costs and effectiveness can be improved by the use
of energy and power conservation practices and techniques in each plant.
The wasteload increases with increased water use. Reduced water use
therefore reduced the wasteload, pumping costs, and heating costs, the
last of which can be further reduced by water reuse as suggested
previously.
NON-WATER POLLUTION BY WASTE TREATMENT SYSTEMS
Solid Wastes
Solid wastes are the most significant non-water pollutants associated
with the waste treatment systems applicable to the meat packing
industry. Screening devices of various design and operating principles
are used primarily for removal of large-scale solids such as hair,
paunch manure, and hog stomach contents from waste water. These solids
may have some economic value as inedible rendering material, or they may
be landfilled or spread with other solid'wastes.
The solids material, separated from the waste water stream, that contain
organic and inorganic matter, including those added to aid solids
separation, is called sludge. Typically, it contains 95 to 98 percent
water before dewatering or drying. Both the primary and secondary
treatment systems generate some quantities of sludge; the quantity will
vary by the type of system and is roughly estimated as follows:
130
-------
Treatment System
Dissolved air flotation
Anaerobic lagoon
Aerobic and aerated lagoons
Activated sludge
Extended aeration
Anaerobic contact process
Rotating biological ccntactor
Sludge Volume as Percent of raw
waste water volume
Up to 10%
Sludge accumulation in these
lagoons is usually not sufficient
to require removal at any time.
10 - 15%
5 - 10%
approximately 2%
unknown
The raw sludge can be concentrated, digested, dewatered, dried, incin-
erated, land^filled or sub-surface injected on-site, or spread in sludge
holding ponds. The sludge from any of the treatment systems, except air
flotation with polyelectrolyte chemicals added, is amenable to any of
these sludge handling processes.
The sludge from air flotation with chemicals has proven difficult to
dewater. A dewatered sludge is an acceptable land fill material.
Sludge from secondary treatment systems is normally ponded by the meat
industry plants on their own land or dewatered or digested sufficiently
for hauling and deposit in public land fills. The final dried sludge
material can be safely used as an effective soil builder. Prevention of
run-off is a critical factor in plant-site sludge holding ponds. Costs
of typical sludge handling techniques for each secondary treatment
system generating sufficient quantities of sludge to require handling
equipment are already included in the costs for these systems,
Air^Pollutign
Odors are the only significant air pollution problem associated with
waste treatment in the meat packing industry. Malodorous conditions
usually occur in anaerobic waste treatment processes or localized
anaerobic environments within aerobic systems. However, it is generally
agreed that anaerobic pcnds will not create serious odor problems unless
the process water has a high sulfate content; then it most assuredly
will. Sulfate waters are definitely a localized condition varying even
from well to well within a specific plant. In northern climates,
however, the change in weather in the spring may be accompanied by a
period of increased odor problems.
131
-------
The anaerobic pond odor potential is somewhat unpredictable as evidenced
by a few plants that have odor problems without sulfate waters. In
these cases a cover and collector of the off-»gas from the pond controls
odor. The off-gas is then burned in a flare.
The other potential odor generators in the waste treatment are tanks and
process equipment items for the anaerobic contact process that normally
generate methane. However, with the process confined to a specific
piece of equipment it is relatively easy to confine and control odors by
collecting and burning the off-gases. The high heating value of these
gases makes it worthwhile and standard practice to recover the heat for
use in the waste treatment process.
Odors have been generated by some air flotation systems which are
normally housed in a building, thus localizing, but intensifying the
problem. Minimizing the unnecessary holdup of any skimmings or grease-
containing solids has been suggested as a remedy.
Odors can best be controlled by elimination, at the source, in pref-
erence to treatment for odor control which remains largely unproven at
this time.
Noise
The only material increase in noise within a packing plant caused by
waste treatment is that caused by the installation of an air flotation
system or aerated lagoons with air blowers. Large pumps and an air
compresser are part of an air flotation system. The industry normally
houses such a system in a low-cost building; thus, the substantial noise
generated by an air flotation system is confined and perhaps amplified
by the installation practices. All air compressors, air blowers, and
large pumps in use on intensively aerated treatment systems, and other
treatment systems as well, may produce noise levels in excess of the
Occupational Safety and Health Administration standards. The industry
must consider these standards in solving its waste pollution problems.
132
-------
SECTION IX
EFFLUENT REDUCTION ATTAINABLE THROUGH THE
APPLICATION OF THE BEST PRACTICABLE CONTROL
TECHNOLOGY CURRENTLY AVAILABLE
EFFLUENT LIMITATIONS GUIDELINES
Introduction
The effluent limitations which must be achieved July 1, 1977, are to
specify the degree of effluent reduction attainable through the appli-
cation of the Best Practicable Control Technology Currently Available.
Best Practicable Control Technology Currently Available is generally
based upon the average of the best existing performance by plants of
various sizes, ages, and unit processes within the industrial category
and/or subcategory. This average is not based upon a broad range of
plants within the ireat packing industry, but based upon performance
levels achieved by exemplary plants.
Consideration must also be given to:
o The total cost of application of technology in relation to
the effluent reduction benefits to be achieved from such
application;
o The size and age of equipment and facilities involved;
o The processes employed;
o The engineering aspects of the application of various types
of control techniques;
o Process changes;
o Non-water quality environmental impact (including energy
requirements).
Also, Best Practicable Control Technology Currently Available emphasizes
treatment facilities at the end of a manufacturing process, but includes
the control technologies within the process itself when the latter are
considered to be normal practice within an industry.
A further consideration is the degree of economic and engineering
reliability which must be established for the technology to be
"currently available". As a result of demonstration projects, pilot
plants and general use, there must exist a high degree of confidence in
133
-------
the engineering and economic practicability of the technology at the
time of start of construction of installation of the control facilities.
EFFLUENT REDUCTION ATTAINABLE THROUGH THE APPLICATION OF
BEST PRACTICAEIE CONTROL TECHNOLOGY CURRENTLY AVAILABLE
Based on the information contained in Sections III through VIII of this
report, a determination has been made that the quality of effluent
attainable through the application of the Best Pollution Control
Technology Currently Available is as listed in Table 1U. A number of
plants in the industry which have biological treatment systems for which
effluent quality data were available are meeting these standards.
Exceptional cases may arise occasionally that require adjustment. An.
example is a plant that processes a large volume of hides or blood from
other plants in addition to its own. Adjustments can be made to the
effluent guidelines on the basis of information contained in Sections
IV, V, and VII for BOD5r suspended solids, Kjeldahl nitrogen, and
ammonia. The adjustments for exceptions are listed in Table 15. It is
assumed that the grease, phosphorus, and nitrite-nitrate levels are
unaffected.
IDENTIFICATION OF BEST PRACTICABLE CONTROL
TECHNOLOGY CURRENTLY AVAILABLE
Best Pollution Control Technology Currently Available for the meat
packing industry involves biological waste treatment following in^plant
solids and grease recovery steps. To assure that treatment will
successfully achieve the limits specified, certain in-plant practices
should be followed.
1, Reduce water use by shutting off water when not in use,
practicing extensive dry clean-up before washing, and
exercising strict management control over housekeeping and
water use practices, Water use should be controlled at
least to the following values:
Class of Plant liters/1000 kg LWK gal/1000 Ib LWK
Simple slaughterhouse 5,416 650
Complex slaughterhouse 7,U97 900
Low-processing packinghouse 8,333 1000
High-processing packinghouse* 12,U95 1500
*This is for an assumed mix of kill and processing of about 0,65 kg
processed meat products/kg LWK.
13<4
-------
Table 14. Recommended Effluent Limitations for 1 July 1977
Plant
Subcategorv (1)
S imple
Slaughterhouse
Complex
S laughter house
Low- Process ing
Packinghouse
High-Processing
Packinghouset
BOD
kg/ 1000 kg
LWK
0.08
0.17
0.12
0.24
Suspended
Solids
kg/ 1000 kg
LWK
0.18
0.22
0.20
0.31
Grease
mg/1
10
10
10
10
tlhe values for BODs and suspended solids are for average plants; 'i.e., plants
with a ratio of average weight of processed meat products to average LWK of
0.55. Adjustments can be made for high-processing packinghouses at other
ratios according to the following equations:
kg BOD5/1000 kg LWK = 0.21 + 0.23 (y - 0.4)
kg SS/1000 kg LWK = 0.28 + 0.30 (y - 0.4)
where y = kg processed meat products/kg LWK.
(l)For all subcategories pH should range between 6.0 and 9.0 and fecal coliform
bacteria should be controlled to 400 counts/100 ml at any time.
135
-------
Table 15. Adjustment Factors for Exceptions in
Plant Subcategories—1977
Exceptional Practice
Processing hides from other
plants in addition to own:
Defleshing, washing,
cur ing
Processing blood from other
plants in addition to own:
Steam coagulation and
s cr e en ing , s ewer ing
water
Rendering material from
other plants in addition
to own:
Wet and low-temperature,
sewering water
Dry
Adjustment Factors j
BOD5
0.02
0.02
0.03
0.01
Suspended
Solids
0.04
0.04
0.06
0.02
Incremental ,
Adjustment = (Adjustment (Total weight of source animals* in 1000's kg)
to Guidelines, Factor) X (Plant LWK in 1000's kg)
*Source animals are those animals killed at another location from which the
additional hides, blood, etc., originate. If the source animal weight is
unknown it can be estimated by the use of the following:
For blood:
Source animal weight
in 1000's kg
(liters of blood) x (0.028) or (gal of blood) x (0.108)
= (kg °f
(0'029) °r
°f blood) x (0'013)
For rendering material:
Source animal weight _ (kg of rendering materials) x (0.0067) or
in 1000' s kg (Ib of rendering materials) x (0.003)
For cattle hides;
Source animal weight
in 1000' s kg
, , . . . .„ . ,_.
°f hldes) X (0'A5)
136
-------
The above values of water use represent the averages for the
subcategories. They vary because of differences in water
requirements and, to a 1- sser extent, practices for subcategories.
The 1977 effluent guidelines were based on these water flows.
It is possible for each ..ubcategory to achieve its flow rate
without large in-plant modifications; however, many plants
will require greatly improved water control and housekeeping practices.
2. In-plant recovery systems should include, as a minimum, a
gravity catch t-isin with at least a 30-minute detention time;
further additic;: of air flotation is more effective.
3. Blood recovery hould be practiced extensively, with all
major bleeding . reas curbed and with separate drains to
blood collectic. tanks. If blood is coagulated, blood
water should be evaporated.
4. Water from lew iemperature rendering should be evaporated.
5. Barometric leg *vaporators which tend to foam, such as for
tankwater evaporation, should be equipped with foam breakers
and demisters.
6. Uncontaminated ooling water should not be discharged to
the secondary w iste treatment system.
7. Paunch contents should be dumped without using water.
The above in-plant practices, in addition to good housekeeping, can
readily produce a raw wa::te load below that cited as average in section V.
With an average waste lc;d, the following secondary treatment systems
are able to meet the stated guidelines:
1. Anaerobic lagoon + aerated + aerobic (shallow) lagoon
2. Anaerobic lagocn + extended aeration
3. Anaerobic -centart process + aerobic (shallow) lagoons
4. A solids removal, stage and chlorination may be required as
a final process.
RAT = ONALE FOR THE SELECTION OF
BEST^PRACTICAEIE' CONTROL,TECHNOLOGY CURRENTLY^AVAILAELE
Age_and^Size of Equipmert^and_Facilities
The industry has generally modernized its plants as new methods that are
economically attractive have been introduced. No relationship between
age of production plant ind effectiveness of its pollution control was
137
-------
found. Also, size is not a significant factor, even though plants vary
widely in size. Small plants are not mechanized to the extent of the
rest of the industry; still they are able to achieve at least as
effective control as larger plants. This is partly because the small-
scale of operation permits options for simple paunch viscera and blood
disposal, with small low-cost in-»plant equipment that are not open to
large operations because of the immense volume of materials concerned.
Total^CQStTgf,Applicatignvin^gl§tion to Effluent^Reduction^Benefitg
Based on the information contained in Section VIII of this report, the
industry as a whole would have to invest an estimated amount of b $52.8
million to achieve the effluent limitations described. This amounts to
a cost of about $2,355 for installed capacity of one million kg LWK
($1,069 per one million Ib) per year. The cost increase will amount to
about $0.345/1000 kg LWK ($0.157/1000 Ib LWK). Based on an estimated
overall investment of $1.7 billion, the maximum increase in investment
would be about 3 percent. This also represents about 20 percent of the
capital expenditures reported for 1971. 3S
All plants discharging to streams can implement the Best Pollution
Control Technology Currently Available. The technology is not affected
by different processes used in the plants.
Engineering Aspects, of control T^chnigue^Applications
The specified level of technology is practicable because it is being
practiced by plants representing a wide range of plant sizes and types.
The parameters pH and fecal coliform are limited for all subcategories
as discussed under "Simple Slaughterhouses.11
Simple_Slaughterhouses
The BODS guideline was taken as the average of five plants in the sub-
category. The average was 0.076 kilograms per 1000 kilograms live
weight killed (kg/kkg LWK). A sixth plant that was very unusual in its
operation came in the same range, but was not included in the average.
A seventh plant (but one that discharged to a municipal system) had an
extremely low raw waste load and, with the less than an outstanding
biological treatment, would have readily met the requirement. Of the
five plants used for the average, three had final BODS values less than
the standard.
The suspended solids content varied much more widely among the five
plants above, with an average of 0.18 kg/1000 kg LWK. Of these five
plants, two were particularly high in suspended solids—between 0.3 and
138
-------
0.4 A suspended solids level that is higher than the BODS level is
normally encountered for biological treatment systems particularly those
which are highly efficient in BOD reduction. As a further check on the
vercity of this number it was determined that three of the exemplary
biological treatment systems averaged about 97 percent removal of
suspended solids. When this factor was applied to the average suspended
solids of the raw waste load for the subcategory of 5.6 kg/1000 kg LWK,
the result was 0.17 kg/1000 kg Iwk. Plant operation with a lower than-
average raw waste load and with a similar treatment system would give a
suspended solids value well within the guideline.
The average grease content in the treated effluent from the five plants
was below the range of the reliability of the analytical method used for
grease (10 mg/1) . This limit would give a grease value of about 0.03
kg/1000 kg LWK. From the removal efficiency standpoint, 98 to 99
percent was achieved in the better plants. These efficiencies would
reduce the grease in the average raw waste to the limit specified.
Control of pH in the range of 6.0 to 9.0 is as commonly encountered in
raw waste and treated effluents; control of fecal coliform to 400 counts
per 100 mg/1 is readily accomplished by chlorination.
Com£lex_ Slaughterhouses
BODS limitations for complex slaughterhouses are based upon averages of
actual effluent data for four plants in the subcategory. Suspended
solids proved quite variable for plants in this subcategory; in several
instances raw wastes at the same or lower suspended solids level as
simple slaughterhouses were not as effectively removed. The limitation
is at a level achieved by one plant in this subcategory, five plants
with similar raw wastes in the simple slaughterhouse subcategory, and
within 25-30 percent of the suspended solids for two other plants in the
subcategory. The limit is approximately 30 mg/1 in concentration as
further verified by using the average raw waste load for the 13 better
plants and the recommended flowrate of 900 gal/1000 Ib Iwk.
The grease level was determined from the average of the five grease
values reported by the best 13 complex slaughterhouses mentioned above
for which the average raw waste load was 2.7 kg grease/1000 kg LWK.
Although there were no exemplary treatment systems for this subcategory,
North Star field tests showed one plant to be below the analytical test
limit for grease, while questionnaire data showed that another plant was
just slightly over this amount.
139
-------
Low-Processing Packinghouses
As outlined in Section V, BOD and suspended solids vary primarily with
kill rather than processing rate. As a consequence, limits for these
parameters in this sutcategory may be partically verified by knowing
kill rates in low processing packinghouses and simple and complex
slaughterhouses. Since kill rates for this subcategory typically fall
between those for the slaughterhouse subcategories, raw waste and
effluent BOD and suspended solids would show the same relationships if
the same treatment technology were applied. Available data revealed the
relationship to be expected even though treatment systems for this
subcategory showed rather poor performance. However, one plant already
meets the limits for both parameters and the addition of mechanical
aeration and measures to reduce raw waste loads would readily permit
four more plants to meet the limits. No correction was applied for the
amount of processing in this subcategory because the ratio of processed
products to LWK was so low that any adjustment was not significant. The
value obtained for grease corresponded to a concentration of 4.5 mg/1
for a plant with average flow (7842 1/1000 kg LWK). Again this is below
the reliable limit of the method analysis, which is 10 mg/1; hence, 10
mg/1 was chosen as the limit.
High-Processing Packinghouse.s
—*_ r^r* L^_ i_--rt-i ••—^-*j-_i_ ^ ^LJ^^M^T^
The BOD5 and suspended solids effluent limits were derived by applying
the exemplary treatment technology proven in use by plants in the other
three subcategories to the average raw waste values given in Table 5 for
this subcategory. This resulted in effluent limit values of 0.24 kg
BOD5/1000 LWK and 0.31 kg suspended solids/1000 kg LWK; these values
apply to a high-processing packinghouse that has a ratio of average
weight of processed products to average LWK of 0.55. However, because
the amount of processed products relative to the LWK varies considerably
for highprocessing packinghouses, adjustments for BOD5 and suspended
solids were developed for plants having a ratio of average weight of
processed products to average LWK other than 0.55. These adjustments
are presented at the bottom of Table 14. The adjustment equations were
derived from two equations for predicting the total BODS and suspended
solids in the raw effluent from the LWK and amount of processed
products, and by assuming exemplary treatment removals for BOD5 and
suspended solids of 98.5 and 97 percent, respectively. The two
predicting equations were developed from a multiple regression analysis
of the combined raw waste data for both low- and highprocessing
packinghouses.
The use of the same proven technology regarding grease showed that for
the raw wastes from eight plants in the subcategory, the final effluent
140
-------
would contain no more than the specified limit at the level of
reliability for the analytical method for the grease determination.
Process Changes
Significant in-plant changes will not be needed by the vast majority of
plants to meet the limits specified. Many plants will need to improve
their water conservation practices and housekeeping, both responsive to
good plant management control. Some plants may find that addition of
improved gravity separation systems, such as air flotation with chemical
precipitation, may enable them to meet the guidelines more readily.
Non-Water Quality^Environmental Impact
The major impact when the option of an activated sludge-type of process
is used to achieve the limits will be the problem of sludge disposal.
Nearby land for sludge disposal may be necessary^—in some cases a sludge
digester (stabilizer) may offer a solution. Properly operated activated
sludge-type systems should permit well conditioned sludge to be placed
in small nearby soil flcts for drying without great difficulty.
Another problem is the odor that emits periodically from anaerobic
lagoons. Covering with a plastic sheet and burning the off-gas offers a
potential solution to this problem. It is necessary to avoid high-
sulfate water supplies. The odor problem can be avoided with all
aerobic systems.
It is concluded that no new kinds of impacts will be introduced by
application of the best current technology.
-------
SECTION X
EFFLUENT REDUCTION ATTAINABLE THROUGH THE APPLICATION OF
THE BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE —
EFFLUENT LIMITATIONS GUIDELINES
INTRODUCTION
The effluent limitations which must be achieved no later than July 1,
1983, are not based on an average of the best performance within an
industrial category, but are determined by identifying the very best
control and treatment technology employed by a specific point source
within the industrial category or subcategory, or by one industry where
it is readily transferable to another. A specific finding must be made
as to the availability of control measures and practices to eliminate
the discharge of pollutants, taking into account the cost of such
elimination.
Consideration must also be given to:
o The age of the equipment and facilities involved;
o The process employed;
o The engineering aspects of the application of various types
of control techniques;
o Process changes;
o The cost of achieving the effluent reduction resulting
from application of the technology;
o Non-water quality environmental impact (including energy
requirements).
Also, Best Available Technology Economically Achievable emphasizes in-
process controls as well as control or additional treatment techniques
employed at the end of the production process.
This level of technology considers those plant processes and control
technologies which, at the pilot plant, semi-works, and other levels,
have demonstrated both, technological performances and economic viability
at a level sufficient to reasonably justify investing in such
facilities. It is the highest degree of control technology that has
been achieved or has been demonstrated to be capable of being designed
143
-------
for plant scale operation up to and including "no discharge" of
pollutants. Although economic factors are considered in this
development, the costs for this level of control are intended to be the
top-of-the-line of current technology, subject to limitations imposed by
economic and engineering feasibility.
EFFLUENT REDUCTION ATTAINABLE^THROUGH APPLICATION OF
THE BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVAlLE
Based on the information contained in Sections III through VII of this
report, a determination has been made that the quality of effluent
attainable through the application of the Best Available Technology
Economically Achievable is as listed in Table 16, The technology to
achieve these goals is generally available, although it may not have
been applied as yet to a packing plant or on a full scale.
Exceptional cases may arise occasionally that require adjustment in the
guidelines--these include the processing of large quantities of
materials (e.g., hides and blood) from other plants in addition to their
own. Adjustments can be made on the basis of the information contained
in Sections IV, V, and VII for BODS and suspended solids. The
adjustments for exceptions are listed in Table 17. Kjeldahl nitrogen,
ammonia, phosphorus, and nitrite-nitrate levels which are concentration
limited are unaffected.
It should also be pointed out that a packer should consider land
disposal, and hence no discharge, for 1983. Where suitable land is
available, evaporation or irrigation is an option that net only is
recommended from the discharge viewpoint, but also will usually be more
economical than the system otherwise required.
IDENTIFICATION OF^THE BEST AVAILABLE^TECHNOLOGY
^ECONOMICALLY ACHIEVABLE
The Best Available Technology Economically Achievable includes that
listed under the Best Practicable Control Technology Currently
Available. In addition, it includes improved pretreatment, such as
dissolved air flotation with pH control and chemical flocculation; an
ammonia control step which may involve ammonia stripping or a
nitrification-denitrification sequence; and a sand filter or equivalent
following secondary treatment.
144
-------
CO
co
CTi
s*.
H
3
CO
cu
a
•rl
•H
O
•H
4->
8
3
rH
UH
4H
t)
CU
T3
CU
o
O
cu
rH
CU
Cfl
H
4-> 4-1 fe;
•H cfl
)-4 )-4 CO
4-1 4-1 CO
*iH *rH
1-3 13
Cfl
3 *
O PL,
CU CO
CO CO
O
A
cfl *
•H •*
G fe5
O
Jen
cfl
*
H C
A ^
bO
*
bO
O
O ^
o ^
^H h-^
--^
M
P
**~*
£*%
j-,
O
4-1 60
d cu
Cfl 4-1
rH Cfl
P-l CJ
ft
3
CO
o o o
\r\ m in
01 CN CN
O
in
CN
....
- * * „
0 O O
rH rH rH
in r^ ^o
o o o
• • •
o o o
fo ~* 5
0 cfl 8 cfl & O
•H rH 0 i-H O cfl
CO CO O CO i-J PL,
O
rH
o
i-H
•
O
ca
o
•
o
60
C
•H +-
CO CU
CO CO
CU 3
0 0
O A
\-t 00
P-i G
1 -H
A r4
bO cj
•H cfl
ffi P-l
limiting.
CO
come
CU
e
o
•H
4J
Cfl
(-1
4J
C
CU
cone
A
rH
CU
rH
CO
•iH
_j_i
ca
4-1
g
e treatm
4_l
CO
ctf
j_.
O
fn
•K
*
plants; i..e.3 plants with ratios of average
CU
bO
cfl
CU
cfl
}_4
O
4-1
cfl
CU
a
m T3
P cu
O co
PQ
(-1
O
4-4
CO
CU
1
cfl
f>
cu
J3
H
f proces
o
4-1
oo
•iH
cu
J3
equations :
bO
•H
O
rH
rH
O
4-4
CU
A
4-1
O
4-1
•H
T3
o
U
U
Cfl
CO
O
•H
4-1
CO
*"
CU
A
4J
o
ouses at
hn
pj
•iH
U
tfl
&"
/""**
<1"
CD
1
>-
^-^
OO
o
o
+
o
o
II
rA
B
60
0
k o
0
i-H
m
p
o
PQ
oo
CJ
o
1
o
rH
•
o
OS
o
d
II
3
00
SS/1000
00
44
.
g
bO
//
CO
o
3
TJ
0
Pu
4-J
cfl
Qj
a
TJ
cu
CO
CO
CU
o
0
Pu
bO
II
CU
(-1
CU
).0 and fecal coliform
w i
T3
CJ
cd
o
1-_.
cu
S
CU
rQ
CU
bO
C
cfl
V-i
Hj
i — 1
3
O
CO
fX
CO
CU
•H
S-i
O
so
subcate
T-H
Cfl
(-1
o
[JH
/— s
! — 1
V~'
01
.g
4-1
Cfl
4-J
Cfl
"a
0
o
i-H
CO
4J
C
3
O
O
O
O
-------
Table 17. Adjustments for Exceptions in All
Plant Subcategories—1983 in kg/kkg LWK
Exceptional Practice
Processing blood from other
plants in addition to own:
Steam coagulation and
s cr eening, sewer ing
water
Rendering material from
other plants in addition
to own:
Wet and low-temperature,
sewering water
Dry
Adjustment Factors
BOD5
0.007
0.01
0.003
Suspended
Solids
0.013
0.02'
0.007
Incremental
Adjustment = (Adjustment (Total weight of source animals* in 1000's kg)
to Guideline, _ . -, x •* °——• • e"-
kg/1000 kg
Factor)
(Plant LWK in 1000's kg)
*Source animals are those animals killed at another location from which the
additional hides, blood, etc., originate. If the source animal weight is
unknown it can be estimated by the use of the following:
For blood;
Source animal weight
in 1000's kg'
Source animal weight _
in 1000's kg
For rendering material;
(liters of blood) x (0.028) or (gal of blood) x 0.108)
(kg of blood) x (0.029) or (Ib of blood) x (0.013)
Source animal weight _ (kg of rendering materials) x (0.0067) or
in 1000's kg (Ib of rendering materials) x (0.003)
For hides;
Source animal weight = (number of hides) x (0.45)
in 1000's kg
146
-------
In-plant controls and modifications are also required to achieve
the specified levels. These include:
o Segregation of grease-bearing from nongrease-bearing waste
streams;
o Water control systems and procedures to reduce water use
to about 50 percent of that listed in Section IX;
o Processing or outside disposal of entire wet pauch contents
or rendering of unopened paunch.
o Installation of surface (or comparable) systems for
heat exchangers and evaporators;
Segregation, clean-up, and reuse of pickling and urine solutions
o Provision for collection of excess solutions;
o Installation of dry rendering operations;
o General elimination of viscera washing operations;
o Design for extensive use of troughs under carcass conveying
lines;
o Instigation and continuous enforcement of meticulous dry
clean-up and materials recovery procedures.
o Elimination of steam coagulation of blood and installation
of whole blood drying equipment.
To reduce the water use to the required levels, several changes in
normal plant operations may be required. Push-to-open valves need to be
used wherever possible. Spray nozzles can be redesigned for lower water
flow. Automatic valves that close when the water is not in use should
be installed; examples are in carcass washers and for washdown
operations. Automatic level control should be used in pen watering
troughs. Pens should be covered in areas where rain and snow are
significant; wood chips should be used for bedding and dry clean-up
procedures should be used.
Water reuse should be practiced, reusing water for lower quality needs.
For example, carcass washing water can be reused for hog dehairing and
lagoon water can be reused for cooling waters (this latter has the
advantage of heating a lagoon for greater biological activity).
Dissolved solids can, be minimized by changing some current practices.
Excess cure solutions should be collected immediately for reuse or
treatment. Concentrated brine overflow from hide curing should be
segregated for salt recovery, perhaps by evaporation. Salt should not
1U7
-------
be used on floors as an antislip material; other methods are available
to counteract this problem. Reducing carcass and head washing water
will reduce the body fluids (and thus the salts) washed into the sewer
in this step.
If suitable land is available, land disposal is the best technology; it
is no discharge. Cepending on the amount and type of land, the above
in-plant techniques and primary treatment, including dissolved air
flotation with pH control, may be adequate before discharging to the
land. On the other hand, a secondary treatment system may be required
before disposal to soil. Any of the systems mentioned in Section IX, or
even simpler ones, are suitable. The potential problem of dissolved
solids in irrigation systems can usually be avoided by minimizing
dissolved solids as described above; in some cases a part of the stream
may need to be treated by ion exchange.
Technology is available for small plants for no discharge via the
irrigation or evaporation or other land disposal methods. Interim or
remedial concepts include irrigation or evaporation or other land
disposal methods. Interim or remedial concepts include a septic tank
used with a drainfield or large cesspool. Strict in-plant controls are
readily managed to minimize the raw waste load.
RATIONALE FOR.SELECTION OF THE
BEST AVAILABLE TECHNoEpGY^ECONOMICALLY ACHIEVABLE
Age and_ Size of Equipment and Facilities
Neither size nor age are found to affect the effectiveness of endof-
process pollution control. Although in-plant control can be managed
quite effectively in older plants, some of the technologies required for
reducing the raw waste loads to the low levels that are possible are
costly to install in older plants. For example, rerouting of sewers to
segregate waste streams is both very difficult and costly.
Small plants, for the reasons discussed in Section IX, have more options
for waste control than do large plants. It is anticipated that most
small plants will find land disposal the best choice.
Total Cost of Application in Relatjon_to
Effluent_ ReductiorTjienef: its ""* ~*
Based on information contained in Section VIII of this report, the
industry as a whole would have to invest up to a maximum of $107 million
above that required to meet the 1977 standards. This amounts to a cost
of about $U760 for installed capacity of one million kg LWK ($2160 for
one million pounds) per year. The operating cost increase will amount
to about $2.10/1000 kg LWK ($0.96/1000 Ib LWK). The capital investment
148
-------
above that to meet the 1977 standards amounts to about six percent of
the total investment of the industry, estimated at about $1.7 billion.
It also equals about 44 percent of the capital investment reported for
the industry for 1971.
All plants discharging to streams can implement the Best Available
Technology Economically Achievable; the technology is not affected by
different processes used in the plants.
Engineering Aspects of^Control Technique Application
The specified level of technology is achievable. It is already being
met for BODS and suspended solids by one plant, both medium and large
plants are included. The limits are not being met, however, for
ammonia, Kjeldahl nitrogen, or phosphorus; newer technology is required
for these parameters. Phosphorus is effectively removed by chemical
treatment in air flotation, and by filtration of the final effluent from
the secondary treatment. The greatest unknown is the nitrification-
denitrification step. However, nitrification has been achieved in pilot
units andon tolimited extent in plant operations. Denitrification has
been explored successfully on laboratory and pilot scales. Ammonia
stripping may require pH adjustment and later neutralization; it is a
technology transferred from other industries.
Each of the identified technologies, except ammonia removal, is
currently being practiced in one or more packing plants. They need to
be combined, however, to achieve the limits specified.
Technology for land disposal is being used by several plants in Texas;
it is already being planned for at least one plant in Iowa. Other
industries, e.g., potato processing, are using it extensively.
Secondary treatment and large holding ponds may be required in the North
to permit land disposal over only about one-half the year. Application
of technology for greatly reduced water use will facilitate land
disposal.
Process^Changes
In-plant changes will be needed by most plants to meet the limits
specified. These were outlined in the "Identification of the Best
Available Technology Economically Achievable", above.
149
-------
Non~Water Quality Impact
The major impact will occur when the land disposal option is chosen.
There is a potential, but unknown, long-term effect on the soil of
irrigation of packing plant wastes. To date, impacts have been
generally obviated by careful water application management.
Otherwise, the effects will essentially be those described in Section
IX, where it was concluded that no new kinds of impacts will be
introduced.
150
-------
SECTION XI
NEW SOURCE PERFORMANCE STANDARDS
INTRODUCTION
The effluent limitations that must be achieved by new sources are termed
performance standards. The New Source Performance Standards apply to
any source for which construction starts after the publication of the
proposed regulations for the Standards. The Standards are determined by
addinq to the consideration underlying the identification of the Rest
Practicable Control Technology Currently Available, a determination of
what higher levels of pollution control are available through the use of
improved production processes and/or treatment techniques. Thus, in
addition to considering the best in-plant and end^of-process control
technology. New Source Performance Standards are based on an analysis of
how the level of effluent may be reduced by changing the production
process itself. Alternative processes, operating methods or other
alternatives are considered. However, the end result of the analysis is
to identify effluent standards which reflect levels of control
achievable through the use of improved production processes (as well as
control technology), rather than prescribing a particular type of
process or technology which must be employed. A further determination
made is whether a standard permitting no discharge of pollutants is
practicable.
Consideration must also be given to:
o Operating methods;
o Batch, as opposed to continuous, operations;
o Use of alternative raw materials and mixes of raw materials;
o Use of dry rather than wet processes (including substitution
of recoverable solvents for water);
o Recovery of pollutants as by-products
151
-------
EFFLUENT REDUCTION ATTAINABLE FOR NEW SOURCES
The effluent limitation for new sources is the same as that for the Best
Practicable Control Technology Currently Available for the pollutants
BOD, suspended solids, ammonia, grease and total kjeldahl nitrogen. In
addition to these pollutant parameters the following additional limits
on nutrients are required for new sources. (See Section IX):
Nitrite-
Phosphorus Nitrate Ammonia
as P as N
**
Plant kg/1000 kg mg/1 kg/kkg LWK
Subcategory LWK
Simple Slaughterhouse 0.03 5.0 0.17
Complex Slaughterhouse 0.07 5.0 0.2U
Low-Processing
Packinghouse 0.07 5.0 0.2U
High-Processing t 0.11 5.0 0.40
Packinghouse
This limitation is readily achievable in newly constructed plants.
However, the guidelines for the Best Available Technology Economically
Achievable should be kept in mind; it may be a practical approach to
design a plant which approaches the 1983 guidelines. Consideration should
also be given to land disposal, which would be no discharge; in many
cases this will be the most attractive and economical option.
**For treatment of these components, concentration becomes limiting at these levels.
tThe values for BOD5 and suspended solids are for average plants; i.e., plants with a ratio of average
weight of processed meat products to average LWK of 0.55. Adjustments can be made for high-processing
packinghouses at other ratios according to the following equations:
kg BODs/1000 kg LWK = 0.07 + 0.08 (y - 0.4)
kg SS/1000 kg LWK - 0.09 + 0.10 (Y - 0.4)
where y = kg processed meat products/kg LWK.
(l)For all subcategories pH should range between 6.0 and 9.0 and fecal coliform bacteria
should be controlled to 400 counts/100 ml at any time.
152
-------
IDENTIFICATION OF NEW SOURCE CONTROL TECHNOLOGY
The technology is the same as that identified as the Best Practicable
Control Technology Currently Available (see Section IX). However,
certain steps that will be necessary to meet the 1983 guidelines should
be considered and, where possible, incorporated. These include:
o In-Plant controls
Segregation of grease-bearing streams from nongrease-
bearing waste streams;
Water control systems and procedures to reduce water
use considerably below those cited in Section IX;
- Processing or cutside disposal of wet paunch contents
or rendering of unopened paunch.
- Installation of shell-in-tube or comparable systems for
heat exchangers and evaporators;
- Provision for collection of excess cure solutions;
Installation of dry rendering operations;
General elimination of viscera washing operations;
- Design for extensive use of troughs under carcass conveying
lines;
Installation of dissolved air flotation, with provision
for a second unit to be added later;
Instigation and continuous enforcement of meticulous
dry clean-up and materials recovery procedures.
o End-of-Process Treatment
- Chemical and biological measures for nutrient
removal, e.g. alum precipitation, nitrification-'
denitrification;
- Land disposal (evaporation, irrigation) wherever possible;
this should be a prime consideration;
Sand filter or microscreen for effluent secondary treatment;
Solid waste drying, composting, upgrading of protein content.
Sludge recycle and/or digestion
153
-------
RATIONALE FOR SELECTION OF BEST AVAILABLE DEMONSTRATED TECHNOLOGY
In addition to the discussion in Section IX on the rationale for Best
Practicable Control Technology Currently Available, additional comments
are presented regarding technology for the added limitations for
nutrients.
Chemical precipitation for removal of phosphorus and residual suspended
solids is an accepted practice as a "polishing" step for biological
treated effluents particularly municipal wastes which contain similar
concentrations of phosphorus as biologically treated meat packing
wastes. Moreover, the general concept of precipition for phosphorus
removal is now serving as the basis guidelines utilized in the State of
North Carolina.
The nitrite^nitrate limits are already being achieved by nine plants in
the State of Iowa (of which two plants simultaneously meet ammonia
requirements). High rate mechanical aeration to volatilize ammonia and
convert ammonia to nitrates is an accepted concept, as is reduction of
nitrates by anaerobic filters or similar denitrification systems.
With further regard to ammonia control as part of total nitrogen
removal, six plants within all subcategories already meet the specified
limits using well operated treatment systems. The ammonia removal is
perhaps incidental to the efficient BOD and suspended solids controls at
these plants and is not directly attributable to specific design
requirements. However, new sources may be availed of most recent
advances in systems for denitrifying effluents using extended air
activated sludge, nitrification-denitrification-nitrogen gas removal,
final clarification, and chlorination with expected high levels of
nitrogen control as outlined in the EPA Technology Transfer Manual,
"Nitrification-Denitrification Facilities, August, 1973".
154
-------
SECTION XII
ACKNOWLEDGMENTS
The assistance of the North Star Research and Development Institute,
Minneapolis, Minnesota is gratefully appreciated. Their program was
directed by Dr. E.E. Erickson; Project Engineers were Messrs John P.
Pilney and Robert J. Reid. Special assistance was provided by North
Star staff members: Mrs. Janet McMenamin, Messrs R.H. Forester and A.J.
Senechal, and Drs. L.W. Rust and L.L. Altpeter.
The contributions and advice of Mr. A.J. Steffen of Purdue University,
Mr. W.H. Miedaner of Glebe Engineering, Mr. John Macon, and Dr. H.O.
Halverson are gratefully acknowledged. Also, James and Paula Wells of
Bell, Galyardt, and Wells made invaluable contributions in numerous
telephone conversations.
Special thanks are due Mr. Jeffery D. Denit, Project Officer, Effluent
Guidelines Division for his guidance in the direction of the program and
for his invaluable help in carrying out all aspects of the research
program.
Intra-agency review, analysis and assistence was provided by the Meat
Products Working Group/Steering Committee comprised of the following EPA
personnel. Mr. George Webster, Effluent Guidelines Division (Chairman)
Mr. Jeffery D. Denit, EGD, Project Officer, Mr. George Keeler, Office
of Research S Development, Mr. Jack Witherow, Officer of Research &
Development, Mr. Gary Polvi, EPA, Region VIII, Mr. William Sonnett,
Office of Enforcement and General Counsel, Mr. Taylor Miller, Office of
General Counsel, Mr. Swep Davis, Office of Planning and Evaluation.
The cooperation of the meat packing industry is greatly appreciated.
The American Meat Institute, the National Independent Meat Packers
Association and the Western States Meat Packers Association deserve
special mention, as dc many companies that provided information and
cooperated in plant visits and sampling programs.
Various Regional EPA offices were most helpful in arranging for site
visits. The plant data provided by Dr. Win. Garner and Mr. Ron Wantock
of the Region VII office in Kansas City were especially appreciated.
155
-------
The help of Dr. Dwight Ballinger of EPA in Cincinnati in establishing
sampling and testing procedures used for the field verification studies
was also appreciated.
Various offices in the United States Department of Agriculture, espe-
cially the Meat and Poultry Inspection Division, and many state and
local agencies were also most helpful. Among these, special mention
should go to the Iowa Water Quality Commission, the state of Ohio
Environmental Protection Administration, and the City and County of
Denver Water and Sanitation District.
Special thanks also go to Mr. Ross Frazier of the Minnesota Department
of Health for periodically running duplicate sets of BOD5 analyses.
The diligence and patience of Mrs. Pearl Smith in helping to edit and
produce this manuscript is gratefully acknowledged.
156
-------
SECTION XIII
REFERENCES
1. Livestock Slaughter, Annual Summary 1972, Statistical Reporting
Service, U.S. Department of Agriculture, Washington, April 1973.
2. The Cost of Clean Water, Industrial Waste Profile No. 8, Meat
Products, U.S. Department of the Interior, Federal Water Pollution
Control Administration, U.S. Government Printing Office, Washington.
3. Pilney, J.P., Halvorson, H.O., and Erickson, E.E., Industrial Waste
Study of the Meat Products Industry, Environmental Protection
Agency, Contract No. 68-01-0031.
4. Standard Industrial Classification Manual, Executive Office of the
President, office of Management and Budget, U.S. Government
Printing Office, Washington, 1972.
5. U.S. Industrial Outlookk, 1973, with Projections to 1980, U.S.
Department of Commerce, U.S. Government Printing Office, Washington.
6. Macon, John A., Ccte, Daniel N., Study of Meat Packing Wastes in
North Carolina, Part I, Industrial Extension Service, School of
Engineering, North Carolina State College, Raleigh, August 1961.
7. Kerrigan, James E., Crandall, Clifford J., Rohlich, Gerard A.,
The Significance of Waste Waters from the Meat Industry as Related
to the Problems of Eutrophication, American Meat Institute, Chicago,
November 1970.
8. Industrial Waste Water Control: Chemical Technology, Volume 2,
C. Fred Gurnham, Ed., Academic Press, New York, 1965.
9. Wells, W. James, Jr., "How Plants Can Cut Rising Waste Treatment
Expense", The National Provisioner (July 4, 1970).
10. Miedaner, W.H., "In-Plant Waste Control", The National Provisioner
(August 19, 1972) .
11. Witherow, Jack L., Yin, S.C., and Farmer, David M., National Meat-
packing Waste Management Research and Development Program,
Robert S. Kerr Environmental Research Lab., EPA, Ada, Oklahoma, 1973.
12. Elimination of water Pollution by packinghouse Animal Paunch and
Blood, Environmental Protection Agency, U.S. Government Printing
Office, Washington, November 1971.
157
-------
13 Personal communication, W.H. Miedaner, 1973.
14. Basics of Pollution Control, Gurnham & Associates, prepared for
Environmental Protection Agency, Technology Transfer Program,
Kansas City, Mo., March 7-8, 1973, Chicago, Illinois.
15. An Industrial Waste Guide to the Meat Industry, U.S. Department of
Health, Education, and Welfare, Washington, revised 1965.
16. Public Health Service Drinking Water Standards, Revised 1962, U.S.
Department of Health, Education and Welfare, U.S. Public Health
Service Publication No. 956, U.S. Government Printing Office,
Washington, 1962.
17. Steffen, A.J., In-Plant Modifications to Reduce Pollution and
Pretreatment of Meat Packing Waste Waters for Discharge to Municipal
Systems, prepared for Environmental Protection Agency Technology
Transfer Program, Kansas City, Missouri, March 7-8, 1973.
18. Water Quality Improvement by Physical and Chemical Processes,
Earnest F. Gloyna and W. Wesley Eckenfelder, Jr., Eds., University
of Texas Press, Austin, 1970.
19. Telephone communication with M. Hartman, Infilco Division, Westing-
house, Richland, Virginia, May 1973.
20. Rosen, G.D., "Profit from Effluent", Poultry Industry (April 1971).
21. Upgrading Meat Packing Facilities to Reduce Pollution: Waste
Treatment Systems, Bell, Galyardt, Wells, prepared for Environmental
Protection Agency Transfer Program, Kansas City, Missouri, March 7-8,
1973, Omaha.
22. "Direct Oxygenaticn of Waste Water", Chemical Engineering (November 29,
1971) .
23. Gulp, Russell L. , and Gulp, Gordon L., Advanced Waste Water Treatment,
Van Nostrand Reinhold Company, New York, 1971.
2<4. Babbitt, Harold E., and Baumann, E. Robert, Sewerage and Sewage
Treatment, Eighth ed., John Wiley & Sons, Inc., London, 1967.
25. Fair, Gordon Maskew, Geyer, John Charles, and Okun, Daniel
Alexander, Water and Waste Water Engineering: Volume 2. Water
Purification and Waste Water Treatment and Disposal, John Wiley &
Sons, Inc., New York, 1968.
26. Personal communication, Thor Alexander and Gary Glazer, 1973.
158
-------
27. Fair, Gordon Maskew, Geyer, John Charles, and Okun, Daniel
Alexander, Water and Waste Water Engineering: Volume 1. Water
Supply and Waste Water Removal, John Wiley & Sons, Inc., New York,
1966.
28. Eckenfelder, W. Wesley, Jr., Industrial Water Pollution Control,
McGraw-Hill Bock Company, New York, 1966,
29. Personal communication, C.E. Clapp, United States Department of
Agriculture, Agricultural Research Service, University of Minnesota,
Minneapolis, May 1973,
30. Eliassen, Rolf, and Tchobanoglous, George, "Advanced Treatment
Processes, Chemical Engineering (October 14, 1968).
31. Knowles, Chester I., Jr., "Improving Biological Processes",
Chemical Engineering/Deskbook Issue (April 27, 1970).
32. Personal Communication, H.o. Halvorson, May 1973.
33. McGraw-Hill's 1972 Report on Business & the Environment,
Fred C. Price, Steven Ross and Robert L. Davidson, Eds,,
McGraw-Hill Publications Co., New York, 1972.
34. Rickles, Robert N., Membranes, Technology and Economics, 1967,
Noyes Development Corporation, Park Ridge, New Jersey.
35. Financial Facts About the Meat Packing Industry, 1971, American
Meat Institute, Chicago, August 1972.
36. "Survey of Corporate Performance: First Quarter 1973", Business
Week, p. 97 (May 12, 1973) .
37. 1967 Census of Manufactures, Bureau of the Census, U.S. Department
of Commerce, U.S. Government Printing Office, Washington, 1971.
38. Witherow, Jack L., "Small Meat Packers Wastes Treatment Systems,"
presented at the 4th National Symposium on Food Processing Wastes,
Syracuse, New York, March 26^28, 1973.
39. McCarty, P.L., "Anaerobic Waste Treatment Fundamentals—Part Two,
Chemistry and Microbiology," Public Works, 95, 123 (October 1964).
40. Elimination of Water Pollution by Packinghouse Animal Paunch and Blood,
by Beefland International, Inc., for EPA, Project #12060 FDS, November
1971.
41. Goodrich, R. D., and Meiske, J. C., The Value of Dried Rumen Contents
As A ration for Finishing Steers, University of Minnesota Department
of Animal Science in cooperation with Agricultural Extension Service
159
-------
and Agricultural Experiment Station, report B-124, 1969.
42. Pilot Plant Installation for Fungal Treatment of Vegetable Canning
Wastes, by the Green Coant Company, for EPA, Grant No. 12060 EDZ,
August 1971.
43. Church, Brooks D., Erickson, E. E., and Widmer, Charles M., "Fungal
Digestion of Food Processing Wastes," Food Technology, 27, No. 2,
44. Preproposal to EPA, Ada, Oklahoma: "Conversion of Rumen Contents of
Beef Cattle to Fungal Protein," North Star Research and Development
Institute, May 1972.
45. Chittenden, Jimmie A., and Wells, W. James, Jr., "BOD Removal and
Stabilization of Anaerobic Lagoon Effluent Using a Rotating Biological
Contactor," presented at the 1970 Annual Conference, Water Pollution
Control Federation, Boston.
46. Private communication from Geo. A. Hormel & Company, Austin,
Minnesota, 1973.
47. U. S. Environmental Protection Agency, "Nitrification-
Denitrification Facilities," Technology Transfer, August, 1973.
160
-------
SECTION XIV
GLOSSARY
Abattoir: A slaughterhouse.
"Act": The Federal Viater Pollution Control Act Amendments of 1972.
Activated Sludge Process: Aerated basin in which waste waters are
mixed with recycled biologically active sludge for periods of about
six hours.
Aerated: The introduction and intimate contacting of air and a
liquid by mechanical means such as stirring, spraying, or bubbling.
Aerobic: Living or occurring only in the presence of dissolved or
molecular oxygen.
Algae: Major group of lower plants, single and multi-celled,
usually aquatic and capable of synthesizing their foodstuff by
photosynthesis.
Ammonia Stripping: Ammonia removal from a liquid, usually by intimate
contacting with an ammonia^free gas such as air.
Anaerobic: Living or active only in the absence of free oxygen.
Bacteria: Primitive plants, generally free of pigment, which
reproduce by dividing in one, two, or three planes. They occur as
single cells, chains, filaments, well-oriented groups or amorphous
masses. Most bacteria do not require light, but a limited number
are photosynthetic and draw upon light for energy. Most bacteria
are heterotrophic (utilize organic matter for energy and for
growth materials), but a few are autotrophic and derive their bodily
needs from inorganic materials.
Barometric Condenser: A mechanical device to condense vapors by the
direct and intimate contacting of the vapors and the cooling water.
Bedding: Material, usually organic, which is placed on the floor
surface of livestock buildings for animal comfort and to absorb urine
and other liquids, and thus promote cleanliness in the building.
161
-------
Biological Oxidation: The process whereby, through the activity of
living organisms in an aerobic environment, organic matter is
converted to more biologically stable matter.
Biological Stabilization: Reduction in the net energy level of
organic matter as a result of the metabolic activity of organisms,
so that further biodegradation is very slow.
Biological Treatment: Organic waste treatment in which bacteria
and/or biochemical action are intensified under controlled conditions.
Blood Water (Serum): Liquid remaining after coagulation of the blood.
Blowdown: A discharge of water from a system to prevent a buildup
of dissolved solids in a boiler.
BODS: A measure of the oxygen consumption by aerobic organisms
over a 5 day test period at 20°C. It is an indirect measure of
the concentration of biologically degradable material present in
organic wastes contained in a waste stream.
Capacity-Cost Relationship: The variation of investment cost for
equipment or a total plant as a function of its size or capacity.
Capacity-Ratio Exponent (n): In capacity-cost relationships, cost
usually increases at a slower rate than capacity. The ratio of
capacities of an exponential power (n) in estimating investment cost
at one capacity, given the cost at a different capacity: e.g.,
(C!/C2)n (cost of C2 = Cost of C1.
Carbon Adsorption: The separation of small waste particles and
molecular species, including color and odor contaminants, by attach-
ment to the surface and open pore structure of carbon granules or
powder. The carbon is usually "activated", or made more reactive
by treatment and processing.
Casings: The cleaned intestines of cattle, hogs, or sheep used as a
case for processed meat such as sausage.
Category and Subcategory: Divisions of a particular industry which
possess different traits that affect raw waste water quality.
Chemical Precipitation: A waste treatment process whereby substances
dissolved in the waste water stream are rendered insoluble and form
a solid phase that settles out or can fce removed by flotation
techniques.
Chitterling: Large intestine of hogs.
162
-------
Clarification: Process of removing undissolved materials from a
liquid. Specifically, removal of solids either by settling or
filtration.
Clarifier: A settling basin for separating settleable solids from
Cm: Centimeter.
Coagulant: A material, which, when added to liquid wastes or water,
creates a reaction which forms insoluble floe particles that adsorb
and precipitate colloidal and suspended solids. The floe particles
can be removed by sedimentation. Among the most common chemical
coagulants used in sewage treatment are ferric sulfate and alum.
COD-Chemical Oxygen Demani: An indirect measure of the biochemical
load imposed on the oxygen resource of a body of water when
organic wastes are introduced into the water. A chemical test is
used to determine COD of waste water.
Composting: Present-day composting is the aerobic, thermophilic
decomposition of organic wastes to a relatively s#able humus. The
resulting humus may contain up to 25% dead or living organisms and is
subject to further, slower decay but should be sufficiently stable
not to reheat or cause odor or fly problems. In composting, mixing
and aeration are provided to maintain aerobic conditions. The
decomposition is done by aerobic organisms, primarily thermophilic
bacteria, actinomycetes and fungi. Heat generated provides the
higher temperatures the microorganisms require.
Contamination: A general term signifying the introduction into water
of microorganisms, chemical, organic, or inorganic wastes, or sewage,
which renders the water unfit for its intended use.
Cracklings: The crisp solid residue left after the fat has been
separated from the fibrous tissue in rendering ^ard or tallow.
Curing: A process, method, or treatment involving aging, seasoning,
washing, drying, injecting, heating, smoking or otherwise treating a
product, especially meat, to preserve, perfect, or ready it for use.
Denitrification: The process involving the facultative conversion
by anaerobic bacteria of nitrates into nitrogen and nitrogen oxides.
Digestion: Though "aerobic" digestion is used, the term digestion
commonly refers to the anaerobic breakdown of organic matter in water
solution or suspension into simpler or more biologically stable
compounds or both. Organic matter may be decomposed to soluble
organic acids or alcohols, and subsequently converted to such gases
as methane and carbon dioxide. Complete destruction of organic solid
materials by bacterial action alone is never accomplished.
163
-------
Dissolved Air Flotation: A process involving the compression of air
and liquid, mixing to super-saturation, and releasing the pressure to
generate large numbers of minute air bubbles. As the bubbles rise to
the surface of the water, they carry with them small particles that
they contact. The process is particularly effective for grease removal.
Dissolved Oxygen: The oxygen dissolved in sewage, water, or other
liquid, usually expressed as milligrams per liter or as percent of
saturation.
Effluent: Liquid which flows from a containing space or process unit.
Electrodialysis: A physical separation process which uses membranes
and applied voltages to separate ionic species from water.
Eutrophication: Applies to lake or pond - becoming rich in dissolved
nutrients, with seasonal oxygen deficiencies.
Evapotranspiration: Loss of water from the soil, both by evaporation
and by transpiration from the plants growing thereon.
Extended Aeration: A form of the activated sludge process except
that the retention time of waste waters is one to three days.
Facultative Bacteria: Bacteria which can exist and reproduce under
either aerobic or anaerobic conditions.
Facultative Decomposition: Decomposition of organic matter by
facultative microorganisms.
Feed: A material which flows into a containing space or process unit.
Filtration: The process of passing a liquid through a porous medium
for the removal of suspended material by a physical straining action.
Floe: A mass formed by the aggregation of a number of fine suspended
particles.
Flocculation: The process of forming larger masses from a large
number of finer suspended particles.
Floe Skimmings: The flocculent mass formed on a quieted liquid
surface and removed for use, treatment, or disposal.
Full-Line Plant: A packinghouse that slaughters and produces a
substantial quantity cf processed meat products.
164
-------
Green Hides: Animal hides that may have been washed and trimmed,
but have not been treated, cured, or processed in any manner.
Hectare: A metric measure of area equivalent to 100 ares (also metric)
and 2.47 acres.
Hydrolyzing: The reaction involving the decomposition of organic
materials by interaction with water in the presence of acids or
alkalies. Hog hair and feathers, for example, are hydrolyzed to
a proteinacous product that has some feed value.
Influent: A liquid which flows into a containing space or process unit.
Ion Exchange: A reversible chemical reaction between a solid and a
liquid by means of which ions may be interchanged between the two.
It is in common use in water softening and water deionizing.
Kg: Kilogram or 1000 grams, metric unit of weight.
Kjeldahl Nitrogen: A measure of the total amount of nitrogen in the
ammonia and organic fcrrrs in waste water.
KWH: Kilowatt-hours, a measure of total electrical energy consumption.
Lagoon: An all-inclusive term commonly given to a water impoundment
in which organic wastes are stored or stabilized or both.
Locker Plant: Very small meat packing plant that slaughters
animals and may produce processed meat products, it stores meat in
frozen form for its customers.
LWK: Live weight killed, a measure of production in a meat packing
plant, commonly expressed in thousands of kilograms or pounds per day.
M: Meter, metric unit of length.
Micrometer: Also micron, a metric measure of length equal to one
millionth of a meter or 39 millionths of an inch.
Mm: Millimeter = 0.001 meter.
Mg/1: Milligrams per liter; approximately equals parts per million;
a term used to indicate concentration of materials in water.
MGD or MGPD: Million gallons per day.
Microstrainer/microscreen: A mechanical filter consisting of a
cylindrical surface of metal filter fabric with openings of 20-60
micrometers in size.
165
-------
Municipal Treatment: A city or community-downed waste treatment plant
for municipal and, possibly, industrial waste treatment.
New Source: Any building, structure, facility, or installation from
which there is or may be a discharge of pollutants and whose con-
struction is commenced after the publication of the proposed
regulations.
Nitrate, Nitrite: Chemical compounds that include the NO3- (nitrate)
and NO2- (nitrite) ions. They are composed of nitrogen and oxygen,
are nutrients for growth of algae and other plant life, and contribute
to eutrophication.
Nitrification: The process of oxidizing ammonia by bacteria into
nitrites and nitrates.
No Discharge: No discharge of effluent to a water course. A
system of land disposal with no run-off or total recycle of the
waste water may be used to achieve it.
Non-Water Quality: Thermal, air, noise and all other environmental
parameters except water.
Offal: The parts of a butchered animal removed in eviscerating and
trimming that may be used as edible products or in production of
inedible by-products.
Off-Gas: The gaseous products of a process that are collected for
use or more typically vented directly, or through a flare, into
the atmosphere.
Organic Content: Synonymous with volatile solids except for small
traces of some inorganic materials such as calcium carbonate which
will lose weight at temperatures used in determining volatile solids.
Oxidation Lagoon: Synonymous with aerobic or aerated lagoon.
Oxidation Pond: Synonymous with aerobic lagoon.
Packinghouse: Meat packing plant that slaughters animals and also
produces manufactured mea# products such as weiners, sausage, canned
meats, cured products, etc.
Paunch: The first stomach, or rumen of cattle, calves, and sheep.
The contents are sometimes included in the term.
Paunch manure: Contents of the paunch.
166
-------
Peck: The second stomach of a ruminant.
Pens (Holding Pens): The area or building for holding live animals
at meat packing plants prior to slaughter.
Percolation: The movement of water through the soil profile.
pH: A measure of the relative acidity or alkalinity of water. A
pH of 7.0 indicates a neutral condition. A greater pH indicates
alkalinity and a lower pH indicates acidity. A one unit change in
pH indicates a ten fold change in the concentration of hydrogen
ion.
Pickle Solution: A water solution that may contain salt, sugar,
curing or pickling agents, preservatives, and other chemicals. It
is used for injection or soaking of meat to prepare finished meat
products.
Pollutant: A substance which taints, fouls, or otherwise renders
impure or unclean the recipient system.
Pollution: The presence of pollutants in a system sufficient to
degrade the quality of the system.
Polishing: Final treatment stage before discharge of effluent to a
water course, carried out in a shallow, aerobic lagoon or pond,
mainly to remove fine suspended solids that settle very slowly.
Some aerobic microbiological activity also occurs.
Polyelectrolyte Chemicals: High molecular weight substances which
dissociate into ions when in solution; the ions either being bound
to the molecular structure or free to diffuse throughout the solvent,
depending on the sign of the ionic charge and the type of electrolyte.
They are often used as flocculating agents in waste water treatment,
particularly along with dissolved air flotation.
Ponding: A waste treatment technique involving the actual holdup of
all waste waters in a confined space with evaporation and percolation
the primary mechanisms operating to dispose of the water.
Ppm: Parts per million, a measure of concentration, expressed
currently as mg/1.
Pretreatment: Waste Water treatment located on the plant site and
upstream from the discharge to a municipal treatment system.
Primary Waste Treatment: In-Plant by-product recovery and waste water
treatment involving physical separation and recovery devices such as
catch basins, screens, and dissolved air flotation.
167
-------
Processing: Manufacture of sausages, hams, canned meats, smoked meat
products, etc., from fresh meat cuts or ground meats.
Process Water: All water that comes into direct contact with the
raw materials, intermediate products, final products, by-products,
or contaminated waters and air.
Raceway: Circular shaped vat containing brine, agitated by a
paddle wheel and used for brine curing of hides.
Raw Waste: The waste water effluent from the in-plant primary waste
treatment system.
Recycle: The return of a quantity of effluent from a specific unit
or process to the feed stream of that same unit. This would also
apply to return of treated plant waste water for several plant usesf
Rendering: Separation of fats and water from tissue by heat or
physical energy.
Return-on-Assets (ROA): A measure of potential or realized profit as
a percent of the total assets (or fixed assets) used to generate
the profit.
Return-on-Investment (ROI): A measure of potential or realized profit
as a percentage of the investment required to generate the profit.
Reuse: Water reuse, the subsequent use of water following an
earlier use without restoring it to the original quality.
Reverse Osmosis: The physical separation of substances from a
water stream by reversal of the normal osmotic process; i.e., high
pressure, forcing water through a semi-permeable membrane to the
pure water side leaving behind more concentrated waste streams.
Riprap: A foundation or sustaining wall usually of stones and brush,
so placed on an embankment or a lagoon to prevent erosion.
Rotating Biological Contractor: A waste treatment device involving
closely spaced light-weight disks which are rotated through the
waste water allowing aerobic microflora to accumulate on each disk
and thereby achieving a reduction in the waste content.
»
Rumen: The large first compartment of the stomach of a ruminant;
see paunch.
Sand Filter: A filter device incorporating a bed of sand that,
depending on design, can be used in secondary or tertiary waste
168
-------
treatment.
Secondary Processes: Edible and inedible rendering and the processing
of blood, viscera, hide, and hair.
Sedimentation Tank: A tank or basin in which a liquid (water, sewage,
liquid manure) containing settleable suspended solids is retained
for a sufficient time so part of the suspended solids settle out by
gravity. The time interval that the liquid is retained in the tank
is called "detention period". In sewage treatment, the detention
period is short enough to avoid putrefaction.
Secondary Treatment: The waste treatment following primary in-
plant treatment, typically involving biological waste reduction
systems.
Semipermeable Membrane: A thin sheet-like structure which permits
the passage of solvent but is impermeable to dissolved substances.
Septic: A condition characterized by or producing bacterial
decomposition; anaerobic.
Settling Tank: Synonymous with "Sedimentation Tank".
Sewage: Water after it has been fouled by various uses. From the
standpoint of source it may be a combination of the liquid or water-
carried wastes from residences, business buildings, and institutions,
together with those from industrial and agricultural establishments,
and with such groundwater, surface water, and storm water as may be
present.
Shock Load: A quantity of waste water or pollutant that greatly
exceeds the normal discharged into a treatment system, usually
occurring over a limited period of time.
Slaughterhouse: Meat packing plant that slaughters animals to produce
fresh meats. It does not produce manufactured meat products such as
weiners, sausage, canned meats, etc.
Sludge: The accumulated settled solids deposited from sewage or other
wastes, raw or treated, in tanks or basins, and containing more or
less water to form a semi-liquid mass.
Slurry: A solids-water mixture, with sufficient water content to
impart fluid handling characteristics to the mixture.
Stick or Stickwater: , The concentrated (thick) liquid product from
evaporating the tankwater from rendering operations. It is added
to solids and may be further dried for feed ingredients.
169
-------
Stoichiometric Amount: The amount of a substance involved in a
specific chemical reaction, either as a reactant or as a reaction
product.
SS: suspended solids; solids that either float on the surface of,
or are in suspension, in water; and which are largely removable by
laboratory filtering as in the analytical determinate of SS content
of waste water.
Surface Water: The waters of the United States including the
territorial seas.
Tankwater: The water phase resulting from rendering processes,
usually applied to wet rendering.
Tertiary Waste Treatment: Waste treatment systems used to treat
secondary treatment effluent and typically using physical-chemical
technologies to effect waste reduction. Synonymous with "Advanced
Waste Treatment",
Total Dissolved Solids (TDS) : The solids content of waste water that
is soluble and is measured as total solids content minus the
suspended solids.
Tripe: The edible product prepared from the walls of the paunch or
rumen.
Viscera: All internal organs of an animal that are located in the
great cavity of the trunk proper.
Zero Discharge: The discharge of no pollutants in the waste water
stream of a plant that is discharging into a receiving body of water.
170
-------
Multiply (English Units)
English Unit
acre
acre-feet
British Thermal Unit
British Thermal Unit/pound
cubic feet/minute
cubic feet/second
cubic feet
cubic feet
cubic inches
degree Fahrenheit
feet
gallon
gallon/minute
horsepower
inches
inches of mercury
pounds
million gallons/day
mile
pound/square inch (gauge)
square feet
square inches
tons (short)
yard
bbreviation
ac
ac ft
BTU
BTU/lb
cfm
cfs
cu ft
cu ft
cu in
°F
ft
gal
gpm
hp
in
in Hg
Ib
mgd
mi
psig (0.
sq ft
sq in
t
y
by
Conversion
0.405
1233.5
0.252
0.555
0.028
1.7
0.028
28.32
16.39
0.555(°F-32)*
0.3048
3.785
0.0631
0.7457
2.54
0.03342
0.454
3,785
1.609
06805 psig + 1)*
0.0929
6.452
0.907
0.9144
Abbreviatioi
ha
cu m
kg cal
kg cal/kg
cu m/min
cu m/min
cu m
1
cu cm
°C
m
1
I/sec
kw
cm
atm
kg
cu m/day
km
atm
sq m
sq cm
kkg
m
To Obtain (Metric Units)
Metric Unit
hectares
cubic meters
kilogram-calories
kilogram calories/kilogram
cubic meters/minute
cubic meters/minute
cubic meters
liters
cubic centimeters
degree Centigcade
meters
liters
liters/second
kilowatts
centimeters
atmospheres
kilograms
cubic meters/day
kilometer
atmospheres (absolute)
square meters
square centimeters
metric tons (1000 kilograms)
meters
*Actual conversion, not a multiplier
171
-------