FREDERICK E. STONE, HAROLD J. BARNETT, PATRICKJ. HUNTER, GLENN C. ROBERTS, and RICHARD W. NELSON

Processing Wastewater FromTwo Mechanized Salmon Canneries

Introduction

In 1972, Congress approved theFederal Water Pollution Control Act(PL 92-500) which enabled the En­vironmental Protection Agency (EPA)to establish gu idelines and perfor­mance standards for seafood process­ing wastewater.

A survey was made of the industryand the results reported in a series ofdevelopment documents (EPA, 1975).After considering the available infor­mation, the EPA recommended guide­lines limiting the amount of 5-daybiological oxygen demand (80D 5 ),

total suspended solids (TSS), and oiland grease (O&G) in wastewater dis­charged by mechanized salmon canner­ies. Performance standards for bestpractical control technology currentlyavailable (8PCTCA) and best availabletechnology economically achievable(8ATEA) were promulgated in theFederal Register (EPA, 1976).

This study was initiated in responseto industry requests for information

ABSTRACT-Wastewater dischargedfrom seafood processing plants is subjectto the Environmental Protection Agencyregulations and guidelines. This study wasperformed to estimate the amounts andvariability of waste loads from salmoncanneries. The amount of 5-day biolog­ical oxygen demand, total suspended solids,and oil and grease discharged by two mech­anized salmon canneries was determined.Variations in the composition of the pro­cessing wastewater, daily water use, andproduction levels are described. Both can­neries complied with the EPA recommendedeffluent limitations more frequently as dailyproduction increased.

January 1981

concerning treatment systems for fish­processing wastewater. The informa­tion published in the developmentdocuments (EPA, 1975) suggested thatthe amount of waste discharged foreach unit of production varies daily andis different for each cannery. To selecttreatment systems which will complywith the EPA guidelines, it was neces­sary to determine the range, frequency,and causes for the variation in theamount of waste discharged by indi­vidual canneries.

Accordingly, intraday and dailyvariations in the composition of waste­water from two west coast mechanizedsalmon canneries were measured andcompared. Relationships between theamount of processing waste discharged,daily production, water used, and theBOD 5 , TSS, and O&G concentrationsof the wastewater were determined.The long-term average and daily max­imum discharge expected at eachlevel of production were calculatedand compared with the EPA recom­mended guidelines.

Materials and Methods

Cannery Description

Two salmon canneries, designatedas A and 8, were evaluated duringthe 1976 fishing season. 80th canner­ies used standard processing equip-

Frederick E. Stone, Chemist; Harold J. Barnett,Research Chemist; Patrick J. Hunter, ChemicalEngineering Technician; Glenn C. Roberts,Chemist; and Richard W. Nelson, SupervisoryChemical Engineer, are with the UtilizationResearch Division, Northwest and Alaska Fish­eries Center, National Marine Fisheries Service,NOAA, 2725 Montlake Boulevard East, Seattle,WA 98112.

ment, such as mechanical butcheringmachines, sliming tables, gang knives,and can-filling machines. The pro­cessing, canning, retorting, and wash­down procedures were similar to thoseobserved elsewhere in the industry.

In both canneries, heads, tails,and viscera were collected before theyentered the wastewater. Cannery Adelivered this offal to local farmers whoused it as a soil enhancer, while Can­nery B used it in pet food production.Cannery 8 rendered some of the fishheads to recover salmon oil. Bothcanneries processed salmon roe as aby-product.

As is usual in mechanized salmoncanneries, scraps accumulated on thefloor in all the processing areas,especially at the butchering and can­filling machines. These wastes enteredthe wastewater when the plants werewashed using high-pressure hoses. Inaddition, large amounts of waste weredischarged at unscheduled intervals dueto frequent spills, breakdowns, andthe dumping of rendered fish heads androe-processing brine.

Routine wash-down procedures werethorough at the end of the work dayand superficial during lunch time andcoffee breaks. Approximately the sameamount of time, labor, and volumes ofwater were used to clean the equipmentregardless of the duration or rate ofproduction.

In both canneries, a series of flumesand floor drains, covered by grateshaving 2.54 cm (l inch) openings,delivered wastewater from the workareas to an effluent collection sump.When full, the contents of the efflu­ent collection sump were automaticallypumped to a headbox located at theentrance to the wastewater treatmentsystem being investigated. Wastewaterin the headbox was well mixed andrepresentative of the effluent subjectto the EPA guidelines for point sourcesof discharge.

Sampling Techniques

Intraday grab samples were manuallycollected from the headbox. A table ofrandom numbers (Youden and Steiner,1975) was used to select time intervalsbetween samples so that the probability

21

o "--_--'--__-'----_---'.__--'--__'--_--..J

Figure 1. - Water used per unit of production as a functionof daily production.

40 60 80

ProdUC\lon (1.000 kg/day)

Water Used for Each Unitof Production (Flow Ratio)

120100

Both canneries used water more effi­ciently as production increased. Theaverage amount of water used foreach unit of production (flow ratio)decreased as daily production increased(Fig. I). The relative error of the flowratio was :±: 11. 8 percent at each levelof production.

The amount of water used by thebutchering machines, sliming tables,can fillers, and similar processes wasproportional to the duration and rate ofproduction. The average amount ofwater required for wash-down proce­dures and purposes other than produc­tion was relatively constant at all levelsof daily production at both canneries(Fig. 2).

Analytical Results

The composition of the untreatedwastewater from both canneries wasvery similar (Tables 1,2). The concen­tration of waste in the samples fromboth canneries followed similar dis­tribution curves at all levels of dailywater use and production investigated.Although initially highly concentrated,the average composition of the waste­water during wash-down and produc­tion periods was similar.

content of the wastewater from theanalytical results.

Results and Discussion

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The amount of water used for eachunit of production (flow ratio) wasdetermined for each level of produc­tion. The flow ratio was multiplied bythe analytical results to determine thewaste discharged for each unit of pro­duction (EPA, 1975) and then by dailyproduction to obtain the total discharge.

Analytical Techniques

All chemical and biQlogical testswere made according to the methodsdescribed in the 14th edition of StandardMethods (APHA, 1975) or by the EPA(1974). Statistical quality control wasemployed when evaluating the data.Results were considered acceptablewhen duplicate analyses were withinthe 95 percent confidence intervalsestabl ished for these tests (APHA,1975; Youden and Steiner, 1975).

Total suspended solids (TSS) wereseparated from filterable residues (FR)by filtering aliquots of wastewaterthrough a Gelman type A glass-fiberfilter paper (EPA, 1974). The TSS re­tained by the filter paper was weighedafter drying in an oven at 103°-105°Cfor I hour. The FR was determined byevaporating the filtered wastewater to aconstant weight at 103°_105°C.

Total residues (TR) were measuredby evaporating aliquots of wastewaterto constant weights in an oven at103°-105°C.

Values for total residues and filter­able residues were reported after sub­tracting the sodium chloride (NaCl)

I Reference to trade names or commercial firmsdoes not imply endorsement by the NationalMarine Fisheries Service, NOAA.

of including variations in production,water use, or waste concentration (suchas occur during lunch hour, spillage, orwash-down procedures) in each samplewould be proportional to the frequencyof occurrence.

Daily composite samples were ob­tained by combining the individualgrab samples in proportion to thedischarge rate measured at the timethe samples were taken (Harris andKeffer, 1974).

Water used at Cannery A was mea­sured by a rotary-style meter in the citywater line. The flow rate of the waste­water, when samples were collected,was determined by measuring the timerequired to fill the 450 liter (119 gallon)effluent collection sump.

Wastewater from Cannery B flowedthrough a 45.7 cm (18 inch) H-flumebefore entering the collection sump.The height of the wastewater in theflume was continuously monitored by aWestmar 1 ultrasonic probe. The instan­taneous flow rates and daily totals wererecorded with a standard error less than:±: I percent. The accuracy of thismethod was confirmed by emptying a7,571 liter (2,000 gallon) tank of waterthrough the flume at a known flow rate.

Both canneries were plumbed so thatonly water used for production andwash-down procedures was included inthe daily total. Water used for coolingretorts and other purposes not coveredby EPA guidelines was not included inthe totals.

Daily production was determined bytotaling the weight of totes full ofsalmon purchased from the boats andprocessed on a particular day.

The average amount of water used bybutchering machines, sliming tables,can fillers, and similar processes foreach unit of production was estimatedby the slope of the linear regression linewhich correlates daily water use andproduction. The amount of water usedregardless of the amount of fish pro­cessed was estimated by extrapolatingthe ratio of daily water use and produc­tion to zero production.

22 Marine Fisheries Review

Table 1.-lntraday random samples-mechanized salmon processing can·neries A and B.

800Waste concentration (mgtl)

>: No.' ofOJ ObservedD samples Daily Dailyiii

~ 600 Item Cannery Day per day mean SD Min. Max.

a TR A 1 10 3,381 867 1,900 5,000aC> TR A 2 30 1,986 645 956 3,146s>- 400OJ TR B 1 9 2,714 1,058 1,330 4,540D

iii TR B 2 25 3,921 1,114 1,690 5,560Q

TR B 3 15 2,056 1,037 858 4,258~ 200 TR B 4 30 3,790 4,024 38 10.066iii

~ TSS A 1 10 1,680 383 1,062 2,067TSS A 2 30 959 339 395 1,595

020 40 60 80 100 TSS B 1 10 1,936 566 1,062 2,585Production (1.000 kg/day) TSS B 2 9 1,924 979 995 2,590(Least squares linear regression) TSS B 3 20 2,906 1,375 1,595 6,174

TSS B 4 28 2,404 807 1,225 3,235

Figure 2.-Water used for each day's produc-FR A 30 990 424 0 2,490

tion at Canneries A and B. Data points omitted FR B 22 1,522 615 150 3,380

at the request of the canneries. 1 Results accepted when duplicate analyses were within the 95 percent confidenceintervals established for these tests.

Table 2.-Daily composite samples-mechanized salmon processing can-neries A and B.

Waste concentrationNo.' of Observed

samplesItem Unit per day Cannery Mean SD Min. Max.

BOD, mgll 4 A 2,682 939 1,433 3,666BOD, mgtl 12 B 2,490 901 1,347 3,970

TR mgll 4 A 3,198 760 2,090 3,760TR mgll 14 B 3,607 1,036 2,720 5,660

TSS mgll 4 A 1,330 277 1,040 1,668TSS mgll 13 B 1.575 719 460 2,735

FR mgll 4 A 1,868 587 1,050 2,429FR mgll 13 B 2,020 752 867 3,348

O&G mgll 4 A 648 391 239 1,029O&G mgtl 10 B 687 475 246 1,653

TKN mgtl 4 A 417 100 272 466TKN mgll 10 B 388 152 280 641

COD mgt I 4 A 4,462 1,247 2,928 5,782COD mgll 10 B 5,348 2,268 3,434 9,900

TSS% A 42.5 7.2 32.7 49.9

TRTSS

% 13 B 43.6 15.4 16.4 67.9TR

FR% 4 A 57.5 7.2 50.1 67.3

TRFR

% 13 B 56.4 15.4 32.1 83.6TR

1Results accepted when duplicate analyses were within the 95 percent confidenceintervals established tor these tests.

The analysis of numerous grab sam­ples revealed rapid fluctuations in thewaste loads (Fig. 3). The complexitiesof a salmon cannery, however, make itdifficult to associate these fluctuationswith any single event.

Statistical analysis of the data indi­cates a combined relative error due tosampling and analysis of approximately± 8.7 percent for BOD 5 , ± 6.3 percentfor TSS, and ± 8.0 percent for O&G.

Waste Discharged forEach Unit of Production

Both canneries discharged lessBOD 5' TSS, and O&G per unit ofproduction on high-production daysthan on low-production days. Becausethe EPA effluent limitations (definedper unit of raw material processed) arethe same for all levels of production,the untreated wastewater discharged byboth canneries is below EPA recom­mended effluent limitations for BPTCAmore frequently on high-productiondays than on low-production days(Fig. 4, 5).

The EPA limitations favored Can­nery B (Table 3) which reported high­production days more frequently thanCannery A (Fig. 6). Cannery B, how­ever, discharged more waste into theenvironment than Cannery A (Fig. 7).

Daily production levels are deter­mined by the fishing intensity, weather

January 1981

conditions, and factors the canneriesare unable to control. Quality would belost if salmon were held to eliminatelow-production days.

The relative errors for the determina­tion of the amount of waste dischargedfor each limit of production were ap­proximately ± 14.7 percent for BOD 5 ,

23

Time from millal sample (mmutes)

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Table 3.-Frequency 01 values less than EPArecommended eflluentlimnations lor BPCTCA.

Daily 30-dayItem Cannery max. avg,

800, EPA limit N/A' N/A800, A N/A N/ABOD, 8 N/A N/A

TSS' EPA limit 44 26TSS A 76% 5%3TSS 8 80% 40%

O&G' EPA limit 29 11O&G A 95%3 76%O&G 8 95%3 80%

, N/A = not applicable,2Long-term estimates, in percent. EPA limits in~ounds/1 ,000 pounds or kg/l ,000 kg.Values of 5 percent and 95 percent represent

the confidence interval justified by the data,

Figure 3. - Total suspended solids (TSS) concentration of intradayrandom samples from Cannery B, day 4.

60

TSS, 1977-------------------------

O&G,1977

o '----='20,---4""0---6,L0-----JSO'---1,L00-----J120

Production (1,000 kg)

Figure 4. -Daily maximum waste discharge (upper 95 percentconfidence interval vs. daily production and EPA guidelines forBPCTCA), Least squares regression curves fitting data forCanneries A and B,

24

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Figure 5. - Most probable waste discharge vs. dailyproduction and EPA 30-day averages for BPCTCA,Least squares regression curve fitting data for Can­neries A and B,

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20 40 60 80 100

Dally production (1,000 kg)

Marine Fisheries Review

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Dally production (1 000 kg)

Figure 6. -The 1976 daily production at Canneries A and B.Frequency (percent) of values less than correspondingproduction.

Figure 7. - Toial waste discharged each day (upper 95percent confidence interval) vs. daily production.Least squares regression curves fitting data for Can­neries A and B.

± 13.4 percent for TSS, and ± 13.8percent for O&G. At best, additionalsampling would reduce but not elimi­nate sampling and analytical errors(Youden and Steiner, 1975).

Summary and Conclusions

Both canneries discharged lessBODs, TSS, and O&G per unit ofproduction as daily production in­creased. Values less than the EPArecommended effluent limitations be­came more frequent as production in­creased. The bias in favor of largerproduction is a strong case for basingguidelines on local environmental con-

January /98/

siderations rather than daily productionvalues.

Variations in daily production, wateruse, and waste concentration valuesmake it difficult to calculate preciselythe amount of waste discharged foreach unit of production. The relativeerrors for each of these measurementsshould be considered when enforcingguidelines.

Literature Cited

APHA. 1975. Standard methods for the examina­tion of water and wastewater. 14th ed. Am.Public Health Assoc., Am. Water WorksAssoc., Water Pollut. Control Fed., Wash.,D.C., 1,193 p.

EPA. 1974. Methods for chemical analysis ofwater and wastes. U.S. Environ. Prot. Agency,Wash., D.C., 298 p. EPA-625-/6-74-003.

----. 1975. Development document forinterim final effluent limitations guidelinesand proposed new source performance stan­dards for the fi sh meal, sal mon, bottom fi sh,sardine, herring, clam, oyster, scallop, andabalone section of the canned and preservedseafood processing point source category.U.S. Environ. Prot. Agency, Wash., D.C.EPA-440/1-75/041a.

----. 1976. Effluent guidelines and stan­dards for phase" seafoods. Fed. Regist.,July 30, 41(148).

Harris, D. 1., and W. 1. Keffer. 1974. Samplingmethodology and flow measurement tech­niques. U.S. Environ. Prot. Agency, KansasCity, Kans., 117 p.

Youden, W. J., and E. H. Steiner. 1975. Sta­tistical manual of the Association of Offi­cial Analytical Chemists. Assoc. Off. Anal.Chem., Wash., D.C., 88 p.

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