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Characteristics of Effluents in Ten Southeastern Poultry Processing Plants
Characteristics of Effluents in Ten Southeastern Poultry Processing Plants DOUGLAS
HAMM
Richard B. Russell Agricultural Research Center, A.R.S., U.S.D.A., Box 5677, A thens, Georgia 30604 (Received for publication September 7, 1971) ABSTRACT Ten poultry processing plants were sampled at seven inplant locations: outflows from the scalder, chiller, giblet chiller, eviscerating trough, final bird washer, feather and viscera flumes. Several pollution indicating parameters were measured. Great variability was noted in these values, not only among plants, but also among samples taken at different times from the same location. The highest C.O.D. value obtained was 5394 mg. Oj/1. from the scalder. The median for the scalder was 2268 mg. O2/I. followed closely by a median value of 1919 for all waste water coming from the killing defeathering area. The waste water from the killing defeathering complex had a C.O.D. of almost twice that of the eviscerating chilling complex (1919: 1005). Improved techniques and equipment for killing, scalding, and defeathering should prove beneficial in reducing pollution from poultry processing plants. POTOTRY SCIENCE 51: 825-829, 1972
INTRODUCTION
T
HE volume of water used in poultry processing plants per unit of product input has risen rapidly over the past several years. Kahle and Gray (1956) estimated that the use of water in 1955 was approximately one gallon per pound live weight of poultry processed. By the last half of the 1960's, this water use had risen fourfold (Camp, 1969; Brewer, 1969; Hamm, 1970). Concurrent with this rise in water usage, there has been a corresponding rise in waste loading as measured by the Biochemical Oxygen Demand (B.O.D.) of the waste water (Camp, 1969), despite the fact that one should expect a dilution effect due to increased water usage. During this 15 year period several changes have occurred within the processing industry resulting in both increased water usage and increased waste loading. The cumulative effect of these factors is of such proportion that immediate attention is necessary. The study reported herein was undertaken to characterize those specific sites within poultry processing plants which contributed most to effluent waste loads. Sites of heavy load contribution could
then receive more vigorous research efforts to change, modify, and improve processing technology. The ultimate goal, that waste loadings could be reduced at specific sites, would thereby reduce total plant effluent waste loading. PROCEDURE
Samples of plant effluents were collected from ten broiler processing plants in the Southeast. Collections were timed to coincide with peak or midshift processing so as to obtain samples representative of full operation. Within each plant grab samples were collected at the following locations: outflows of the scalder, bird chiller, giblet chiller, eviscerating trough, final bird washer, the feather flume, and viscera flume after screening. To partially negate surface film effects, all samples were drawn from areas of turbulence. Plants were sampled twice, at least one week apart. At each of the seven inplant locations, a one liter and two 500 ml. samples were collected during each visit. Samples collected ahead of inplant screening were passed through a 1.1 mm. screen as collected. Samples obtained at plants that were more than one hour from the
825
826
D. HAMM TABLE 1.-—Waste
water characterization study of 10 poultry processing plants. Reported as milligrams per liter of waste water (mg./l.)1 Solids3 C.O.D.
Fat2
•
Total Scalder High (H) Median (M) Low (L)
N03"
ci-
Phos. Nitrogen4
Residue Volatile
5394 2268 1254
57 30 16
3774 1635 653
798 393 158
2976 1180.5 473
86 14 6
1070 337 32
43 26 9
515 201 74
Feather Flume
H. M. L.
5644 1919 651
324 135 25
3130 974 402
544 182 81
2734 808 321
27 10 2
436 78 7
181 10 3
384 79 9
Chiller
H. M. L.
2817 903 395
1014 165 34
1774 705 320
359 226 124
1448 549 196
87 10 4
547 103 24
23 9 1
87 30 9
Giblet Chiller
H. M. L.
4797 988 437
557 54 21
2891 509 329
468 136 80
2587 403 207
15 9 1
487 73 6
49 6 1
261 30 5
Eviscerating Trough H. M. L.
1514 687 243
476 149 39
841 382 174
242 87 41
651 289 133
9 4 1
212 45 5
17 2 Tr
77 6 1
Final Bird Washer
H. M. L.
1993 379 228
616 85 28
1203 325 213
156 81 60
1113 220 145
9 4 1
46 24 10
3 2 1
19 6 3
Viscera Flume
H. M. L.
1944 1005 542
326 185 80
801 532 351
229 100 27
673 419 281
10 4 1
125 47 4
7 4 1
46 21
1 2 3 4
7
Samples were drawn during full processing and represent values for that specific time. Hexane extractables. Total solids by drying at 103°C.; Residue by firing at 600°C. for 1 hour; and volatile solids by difference. By micro-Kjeldahl method.
laboratory were transported to the laboratory in ice. Upon arrival at the lab. each of the 500 ml. samples was acidified with 3 ml. concentrated HC1, then held at 4°C. until fat could be determined. The one liter samples were immediately heated at 35°C. in a water bath and then the contents homogenized for two minutes in a warmed Waring blender. Aliquots for all determinations other than fat were drawn at this point. Chemical Oxygen Demand (C.O.D.), fat (grease), solids, and phosphorus were determined in accordance with current water pollution control standards (F.W.P.C.A., 1969; and A.P.H.A., 1965). Chloride and nitrate concentrations were determined by using specific ion electrodes and following man-
ufacturer's instructions. Nitrogen was determined by the A.O.A.C. (1965) micro-kjeldahl method. Chemical Oxygen Demand (C.O.D.) was measured in this study rather than B.O.D. due to the inherently non-reproducible nature of B.O.D. tests (Davis, 1971). RESULTS AND DISCUSSION
A summary of the data obtained from the physical and chemical analyses of samples collected in this study is shown in Table 1. Since these samples were col^ lected while plants were in full operation, the data can be used as a good indicator of pollution potentials from various processes studied. Values are reported in Table 1 as median values along with range
POULTRY PROCESSING PLANT EFFLUENTS
rather than the arithmetic mean and standard deviation for reasons which will be discussed later in this paper (see discussion of bird chiller). Scalder. The scalder overflow, with a median C.O.D. value of 2268, was the most highly contaminated of the areas sampled, scoring highest in every category except fat, where it was lowest. A value of 1635 mg./l. for total solids in the scalder is not surprising since any external dirt from the chicken carcass is introduced into the scald water. The high nitrogen level (201 mg./l.) can undoubtedly be accounted for by blood, by feather dust, and by cloacal contents which are voided when the carcass contacts the scald water. Phosphorus, chloride, and nitrate also were highest in the scalder water, however, no special significance is placed on this at this time. Feather Flume. Water in the feather flume originates from four major sources: (a)the killing bleeding area (volume and C.O.D. strength here related to the blood collection system in use), (b) the scalder overflow (usually about one quart per bird), (c) the defeathering processes (both picker sprayers and fluming water which may be recycled from either the feather flume or the eviscerating flume), and (d) the whole bird washers which give the defeathered bird a final washing before evisceration begins. The median C.O.D. value for the feather flume of 1919 mg./l. indicates that some dilution has occurred since this water includes the scald water which has a higher value. However, since this is only 15 percent less than the value of the scald water (2268), it is evident that the bird washer, slaughter area, and pickers are major contributors. If blood is allowed to continually seep into the feather flume, its
827
high B.O.D. value can greatly increase C.O.D. value of the feather flume. The high fat level of 135 mg./l. for the feather flume water was unexpected, especially since very few of the plants sampled were recycling viscera flume water into the feather flow-away flume. This level of fat content probably results from the scrubbing action of the picker fingers on the carcass. Bird Chiller. At the time of this study the amount of water usage in the chiller was more or less controlled by the U.S.D.A. inspection service in as much as minimal waste flows were prescribed ( | gal./bird). Most plants adhere as closely as possible to the minimum overflow required since to exceed this amount would be an added processing expense in cooling the extra water needed. On this basis the outflow from the bird chillers should not be a factor in influencing the variation in values found for the chiller in this study. Data in Table 2 shows values obtained from chiller waste waters from the 10 plants studied for C.O.D. and fats. This data indicates the range between values obtained not only between plants but among samples from the same plant. This variation among plants is attributed to three primary factors: (a) fat content of carcasses from different flocks, (b) grating action on carcasses by different type chillers, and (c) size and age of birds being processed. Different type chillers could not be a factor influencing inplant variation. The high values obtained from the chiller water for all items studied suggests that soluble products are being leached from the bird and are contributing toward plant waste loading. This is further borne out by the relatively high non-volatile solids (residue) found in the chiller water. The values obtained for C.O.D. and
828
D. HAMM
TABLE 2.—Analyses of poultry chiller water from ten processing plants1 {mg./liter) Chemical oxygen demand
Volatile solids2
Fat3
2817 415
1448 352
928 79
1735 1522
978 873
338 282
1499 1362
744 609
419 247
1369 903
579 549
1014 164
1263 798
590 416
376 130
1070
557
189
917 747
540 574
210 165
899 459
345 380
154 73
752 395
381 196
64 34
578 455
368 273
128 87
1050
565
267
903
549
165
1
Samples taken after 2\ hours of operation or more and on separate days. 2 Solids loss when dry matter in sample fired at 600°C. for 1 hour. 3 Hexane extractables. 4 One sample only.
fats from the chiller do not fall in a normal distribution about the arithmetic mean but are extremely skewed with the long tail to the high side. More specifically the fat values for the chiller water as indicated in Table 2 range from a low of 34 mg./l. to a high of 1014 mg./l. The mean value calculates at 267 mg. whereas, the median is 165. Due to the skewness of the values for all processes studied, the author reported high, low, and median values in Table 1, feeling that this would give a more accurate picture for the poultry processing industry.
Giblet Chiller. The wide range between the median value of 988 and the high of 4797, indicates a potential problem area in some plants. Some of this variation could result from the grating action of the equipment used to remove the gizzard lining. It could also indicate variation in water overflow rates alone or in combination with effects of the action of the gizzard cleaner. Finish of the bird could also be a factor since the surface of the gizzard exterior serves as a fat depot and all fat must be removed from the gizzard in processing. Eviscerating Trough. The effluent from the eviscerating trough contains a greater variety of waste products than any other single plant effluent. Since this effluent carries the largest amount of by-product from the processing area, it might be expected to carry a high load of pollutants. Dilution of the flow from bird washer, hand wash nozzles, etc., no doubt, is partially responsible for its lower strength. Also, the trough is smooth sided thereby offering little grating action. The samples collected excluded any large particles. The relatively high fat content (149) would seem reasonable because of the fat losses from eviscerating operations. Final Bird Washer. Theoretically, there should be, at least in part, an inverse relationship between the values of the final bird washer effluent and the bird chiller effluent as the more effective the washer, the less organic matter would enter the chiller. This was not the case in this study. The r value for the correlation between total solids in the chiller and final bird washer was —0.03 and for fats the r value was +0.05. The range between high and low values for items studied for the final bird washer could probably be attributed to the variation in effectiveness of bird washers and in the rates of water flow.
829
P O U L T R Y PROCESSING P L A N T E F F L U E N T S
Average values for the final bird washer effluents tend to indicate its low waste loading, but the highs recorded, especially for fat, indicate it is a potential problem area in some plants. Viscera Flume. W a t e r in the viscera, or offal flume, is a composite of water from: (a) the chiller complex, (b) the eviscerating trough, (c) the giblet chiller, and (d) the final bird washer. These waters are all somewhat similar in strength. For the most part, they are much lower in strength than the feather flume water. A similar situation has been reported by Morris (1965) regarding feather and viscera flumes in duck processing plants. The fat content of the viscera flume of 185 mg./l. is higher than any of its contributory sources. The author postulates t h a t this is caused b y both the grating effect of the screening devices and b y abrasive action of the flume walls on the viscera as it is flumed to the screens. General Comments. All sites sampled displayed great variability in values. This variability might be due in part to variation in water usage b u t data from the chillers would indicate t h a t other factors m u s t be of more importance. This variability does indicate the need for proper sampling techniques if absolute values on specific waste outputs from any function over a period of even a few hours is to be obtained. Variability in sample values obtained could be due to several factors, such as: age and finish of birds, types of equipment
used, operating procedures and techniques, and even the water supply. T h e high waste load from the killing defeathering complex could be greatly reduced with better blood handling systems and an improved feather removal system. REFERENCES Association of Official Agricultural Chemists, 1965. Official Methods of Analysis. Assoc. Offic. Agr. Chemists, Washington, D.C. American Public Health Association, 1965. Standard Methods for Examination of Water and Wastewater. American Public Health Association, Inc. New York, N.Y. Brewer, D. L., 1969. Factors influencing the demand for water in poultry processing plants. Thesis for M.S. degree, University of Georgia, Athens, Georgia. Camp, W. J., 1969. Waste treatment and control at Live Oak poultry processing plant. Paper presented at the Eighteenth Southern Water Resources and Pollution Control Conference, North Carolina State University, Raleigh, North Carolina. Davis, E. M., 1971. BOD vs COD vs TOC vs TOD. Water and Wastes Engineering, Feb.: 32-34. Federal Water Pollution Control Administration, 1969. Methods for Chemical Analysis of Water and Wastes. Federal Water Pollution Control Administration, U.S. Dept. of Interior, Analytical Control Laboratory. Cincinnati, Ohio. Hamm, D., 1970. Water pollution potentials from poultry processing plants. Paper presented at Symposium on Pollution of Land, Water, and Air Through Production and Utilization of Agricultural Crops. Northern Development Division. ARS-USDA, Peoria, 111. Kahle, H., and L. Gray, 1956. Utilization and disposal of poultry by-products and wastes. Marketing Research Report No. 143, U.S. Dept. of Agriculture, Washington, D.C. Morris, G. L., 1965. Duck processing waste. U.S. Public Health Service Publication No. 999-WP31, U.S. Dept. of H.E.W., Washington, D.C.
J U N E 7-8. I O W A S T A T E U N I V E R S I T Y N U T R I T I O N ON P R O T E I N S , AMES, IOWA
SYMPOSIUM
HAMM
Richard B. Russell Agricultural Research Center, A.R.S., U.S.D.A., Box 5677, A thens, Georgia 30604 (Received for publication September 7, 1971) ABSTRACT Ten poultry processing plants were sampled at seven inplant locations: outflows from the scalder, chiller, giblet chiller, eviscerating trough, final bird washer, feather and viscera flumes. Several pollution indicating parameters were measured. Great variability was noted in these values, not only among plants, but also among samples taken at different times from the same location. The highest C.O.D. value obtained was 5394 mg. Oj/1. from the scalder. The median for the scalder was 2268 mg. O2/I. followed closely by a median value of 1919 for all waste water coming from the killing defeathering area. The waste water from the killing defeathering complex had a C.O.D. of almost twice that of the eviscerating chilling complex (1919: 1005). Improved techniques and equipment for killing, scalding, and defeathering should prove beneficial in reducing pollution from poultry processing plants. POTOTRY SCIENCE 51: 825-829, 1972
INTRODUCTION
T
HE volume of water used in poultry processing plants per unit of product input has risen rapidly over the past several years. Kahle and Gray (1956) estimated that the use of water in 1955 was approximately one gallon per pound live weight of poultry processed. By the last half of the 1960's, this water use had risen fourfold (Camp, 1969; Brewer, 1969; Hamm, 1970). Concurrent with this rise in water usage, there has been a corresponding rise in waste loading as measured by the Biochemical Oxygen Demand (B.O.D.) of the waste water (Camp, 1969), despite the fact that one should expect a dilution effect due to increased water usage. During this 15 year period several changes have occurred within the processing industry resulting in both increased water usage and increased waste loading. The cumulative effect of these factors is of such proportion that immediate attention is necessary. The study reported herein was undertaken to characterize those specific sites within poultry processing plants which contributed most to effluent waste loads. Sites of heavy load contribution could
then receive more vigorous research efforts to change, modify, and improve processing technology. The ultimate goal, that waste loadings could be reduced at specific sites, would thereby reduce total plant effluent waste loading. PROCEDURE
Samples of plant effluents were collected from ten broiler processing plants in the Southeast. Collections were timed to coincide with peak or midshift processing so as to obtain samples representative of full operation. Within each plant grab samples were collected at the following locations: outflows of the scalder, bird chiller, giblet chiller, eviscerating trough, final bird washer, the feather flume, and viscera flume after screening. To partially negate surface film effects, all samples were drawn from areas of turbulence. Plants were sampled twice, at least one week apart. At each of the seven inplant locations, a one liter and two 500 ml. samples were collected during each visit. Samples collected ahead of inplant screening were passed through a 1.1 mm. screen as collected. Samples obtained at plants that were more than one hour from the
825
826
D. HAMM TABLE 1.-—Waste
water characterization study of 10 poultry processing plants. Reported as milligrams per liter of waste water (mg./l.)1 Solids3 C.O.D.
Fat2
•
Total Scalder High (H) Median (M) Low (L)
N03"
ci-
Phos. Nitrogen4
Residue Volatile
5394 2268 1254
57 30 16
3774 1635 653
798 393 158
2976 1180.5 473
86 14 6
1070 337 32
43 26 9
515 201 74
Feather Flume
H. M. L.
5644 1919 651
324 135 25
3130 974 402
544 182 81
2734 808 321
27 10 2
436 78 7
181 10 3
384 79 9
Chiller
H. M. L.
2817 903 395
1014 165 34
1774 705 320
359 226 124
1448 549 196
87 10 4
547 103 24
23 9 1
87 30 9
Giblet Chiller
H. M. L.
4797 988 437
557 54 21
2891 509 329
468 136 80
2587 403 207
15 9 1
487 73 6
49 6 1
261 30 5
Eviscerating Trough H. M. L.
1514 687 243
476 149 39
841 382 174
242 87 41
651 289 133
9 4 1
212 45 5
17 2 Tr
77 6 1
Final Bird Washer
H. M. L.
1993 379 228
616 85 28
1203 325 213
156 81 60
1113 220 145
9 4 1
46 24 10
3 2 1
19 6 3
Viscera Flume
H. M. L.
1944 1005 542
326 185 80
801 532 351
229 100 27
673 419 281
10 4 1
125 47 4
7 4 1
46 21
1 2 3 4
7
Samples were drawn during full processing and represent values for that specific time. Hexane extractables. Total solids by drying at 103°C.; Residue by firing at 600°C. for 1 hour; and volatile solids by difference. By micro-Kjeldahl method.
laboratory were transported to the laboratory in ice. Upon arrival at the lab. each of the 500 ml. samples was acidified with 3 ml. concentrated HC1, then held at 4°C. until fat could be determined. The one liter samples were immediately heated at 35°C. in a water bath and then the contents homogenized for two minutes in a warmed Waring blender. Aliquots for all determinations other than fat were drawn at this point. Chemical Oxygen Demand (C.O.D.), fat (grease), solids, and phosphorus were determined in accordance with current water pollution control standards (F.W.P.C.A., 1969; and A.P.H.A., 1965). Chloride and nitrate concentrations were determined by using specific ion electrodes and following man-
ufacturer's instructions. Nitrogen was determined by the A.O.A.C. (1965) micro-kjeldahl method. Chemical Oxygen Demand (C.O.D.) was measured in this study rather than B.O.D. due to the inherently non-reproducible nature of B.O.D. tests (Davis, 1971). RESULTS AND DISCUSSION
A summary of the data obtained from the physical and chemical analyses of samples collected in this study is shown in Table 1. Since these samples were col^ lected while plants were in full operation, the data can be used as a good indicator of pollution potentials from various processes studied. Values are reported in Table 1 as median values along with range
POULTRY PROCESSING PLANT EFFLUENTS
rather than the arithmetic mean and standard deviation for reasons which will be discussed later in this paper (see discussion of bird chiller). Scalder. The scalder overflow, with a median C.O.D. value of 2268, was the most highly contaminated of the areas sampled, scoring highest in every category except fat, where it was lowest. A value of 1635 mg./l. for total solids in the scalder is not surprising since any external dirt from the chicken carcass is introduced into the scald water. The high nitrogen level (201 mg./l.) can undoubtedly be accounted for by blood, by feather dust, and by cloacal contents which are voided when the carcass contacts the scald water. Phosphorus, chloride, and nitrate also were highest in the scalder water, however, no special significance is placed on this at this time. Feather Flume. Water in the feather flume originates from four major sources: (a)the killing bleeding area (volume and C.O.D. strength here related to the blood collection system in use), (b) the scalder overflow (usually about one quart per bird), (c) the defeathering processes (both picker sprayers and fluming water which may be recycled from either the feather flume or the eviscerating flume), and (d) the whole bird washers which give the defeathered bird a final washing before evisceration begins. The median C.O.D. value for the feather flume of 1919 mg./l. indicates that some dilution has occurred since this water includes the scald water which has a higher value. However, since this is only 15 percent less than the value of the scald water (2268), it is evident that the bird washer, slaughter area, and pickers are major contributors. If blood is allowed to continually seep into the feather flume, its
827
high B.O.D. value can greatly increase C.O.D. value of the feather flume. The high fat level of 135 mg./l. for the feather flume water was unexpected, especially since very few of the plants sampled were recycling viscera flume water into the feather flow-away flume. This level of fat content probably results from the scrubbing action of the picker fingers on the carcass. Bird Chiller. At the time of this study the amount of water usage in the chiller was more or less controlled by the U.S.D.A. inspection service in as much as minimal waste flows were prescribed ( | gal./bird). Most plants adhere as closely as possible to the minimum overflow required since to exceed this amount would be an added processing expense in cooling the extra water needed. On this basis the outflow from the bird chillers should not be a factor in influencing the variation in values found for the chiller in this study. Data in Table 2 shows values obtained from chiller waste waters from the 10 plants studied for C.O.D. and fats. This data indicates the range between values obtained not only between plants but among samples from the same plant. This variation among plants is attributed to three primary factors: (a) fat content of carcasses from different flocks, (b) grating action on carcasses by different type chillers, and (c) size and age of birds being processed. Different type chillers could not be a factor influencing inplant variation. The high values obtained from the chiller water for all items studied suggests that soluble products are being leached from the bird and are contributing toward plant waste loading. This is further borne out by the relatively high non-volatile solids (residue) found in the chiller water. The values obtained for C.O.D. and
828
D. HAMM
TABLE 2.—Analyses of poultry chiller water from ten processing plants1 {mg./liter) Chemical oxygen demand
Volatile solids2
Fat3
2817 415
1448 352
928 79
1735 1522
978 873
338 282
1499 1362
744 609
419 247
1369 903
579 549
1014 164
1263 798
590 416
376 130
1070
557
189
917 747
540 574
210 165
899 459
345 380
154 73
752 395
381 196
64 34
578 455
368 273
128 87
1050
565
267
903
549
165
1
Samples taken after 2\ hours of operation or more and on separate days. 2 Solids loss when dry matter in sample fired at 600°C. for 1 hour. 3 Hexane extractables. 4 One sample only.
fats from the chiller do not fall in a normal distribution about the arithmetic mean but are extremely skewed with the long tail to the high side. More specifically the fat values for the chiller water as indicated in Table 2 range from a low of 34 mg./l. to a high of 1014 mg./l. The mean value calculates at 267 mg. whereas, the median is 165. Due to the skewness of the values for all processes studied, the author reported high, low, and median values in Table 1, feeling that this would give a more accurate picture for the poultry processing industry.
Giblet Chiller. The wide range between the median value of 988 and the high of 4797, indicates a potential problem area in some plants. Some of this variation could result from the grating action of the equipment used to remove the gizzard lining. It could also indicate variation in water overflow rates alone or in combination with effects of the action of the gizzard cleaner. Finish of the bird could also be a factor since the surface of the gizzard exterior serves as a fat depot and all fat must be removed from the gizzard in processing. Eviscerating Trough. The effluent from the eviscerating trough contains a greater variety of waste products than any other single plant effluent. Since this effluent carries the largest amount of by-product from the processing area, it might be expected to carry a high load of pollutants. Dilution of the flow from bird washer, hand wash nozzles, etc., no doubt, is partially responsible for its lower strength. Also, the trough is smooth sided thereby offering little grating action. The samples collected excluded any large particles. The relatively high fat content (149) would seem reasonable because of the fat losses from eviscerating operations. Final Bird Washer. Theoretically, there should be, at least in part, an inverse relationship between the values of the final bird washer effluent and the bird chiller effluent as the more effective the washer, the less organic matter would enter the chiller. This was not the case in this study. The r value for the correlation between total solids in the chiller and final bird washer was —0.03 and for fats the r value was +0.05. The range between high and low values for items studied for the final bird washer could probably be attributed to the variation in effectiveness of bird washers and in the rates of water flow.
829
P O U L T R Y PROCESSING P L A N T E F F L U E N T S
Average values for the final bird washer effluents tend to indicate its low waste loading, but the highs recorded, especially for fat, indicate it is a potential problem area in some plants. Viscera Flume. W a t e r in the viscera, or offal flume, is a composite of water from: (a) the chiller complex, (b) the eviscerating trough, (c) the giblet chiller, and (d) the final bird washer. These waters are all somewhat similar in strength. For the most part, they are much lower in strength than the feather flume water. A similar situation has been reported by Morris (1965) regarding feather and viscera flumes in duck processing plants. The fat content of the viscera flume of 185 mg./l. is higher than any of its contributory sources. The author postulates t h a t this is caused b y both the grating effect of the screening devices and b y abrasive action of the flume walls on the viscera as it is flumed to the screens. General Comments. All sites sampled displayed great variability in values. This variability might be due in part to variation in water usage b u t data from the chillers would indicate t h a t other factors m u s t be of more importance. This variability does indicate the need for proper sampling techniques if absolute values on specific waste outputs from any function over a period of even a few hours is to be obtained. Variability in sample values obtained could be due to several factors, such as: age and finish of birds, types of equipment
used, operating procedures and techniques, and even the water supply. T h e high waste load from the killing defeathering complex could be greatly reduced with better blood handling systems and an improved feather removal system. REFERENCES Association of Official Agricultural Chemists, 1965. Official Methods of Analysis. Assoc. Offic. Agr. Chemists, Washington, D.C. American Public Health Association, 1965. Standard Methods for Examination of Water and Wastewater. American Public Health Association, Inc. New York, N.Y. Brewer, D. L., 1969. Factors influencing the demand for water in poultry processing plants. Thesis for M.S. degree, University of Georgia, Athens, Georgia. Camp, W. J., 1969. Waste treatment and control at Live Oak poultry processing plant. Paper presented at the Eighteenth Southern Water Resources and Pollution Control Conference, North Carolina State University, Raleigh, North Carolina. Davis, E. M., 1971. BOD vs COD vs TOC vs TOD. Water and Wastes Engineering, Feb.: 32-34. Federal Water Pollution Control Administration, 1969. Methods for Chemical Analysis of Water and Wastes. Federal Water Pollution Control Administration, U.S. Dept. of Interior, Analytical Control Laboratory. Cincinnati, Ohio. Hamm, D., 1970. Water pollution potentials from poultry processing plants. Paper presented at Symposium on Pollution of Land, Water, and Air Through Production and Utilization of Agricultural Crops. Northern Development Division. ARS-USDA, Peoria, 111. Kahle, H., and L. Gray, 1956. Utilization and disposal of poultry by-products and wastes. Marketing Research Report No. 143, U.S. Dept. of Agriculture, Washington, D.C. Morris, G. L., 1965. Duck processing waste. U.S. Public Health Service Publication No. 999-WP31, U.S. Dept. of H.E.W., Washington, D.C.
J U N E 7-8. I O W A S T A T E U N I V E R S I T Y N U T R I T I O N ON P R O T E I N S , AMES, IOWA
SYMPOSIUM