Bioresource Technology 101 (2010) 439–449

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Bioresource Technology

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Review

Biological treatment processes for fish processing wastewater – A review

Pankaj Chowdhury, T. Viraraghavan *, A. SrinivasanFaculty of Engineering, University of Regina, Regina, Saskatchewan, Canada S4S0A2

a r t i c l e i n f o a b s t r a c t

Article history:Received 3 June 2008Received in revised form 10 August 2009Accepted 12 August 2009Available online 13 September 2009

Keywords:WastewaterFish processingAerobicAnaerobic

0960-8524/$ - see front matter � 2009 Elsevier Ltd. Adoi:10.1016/j.biortech.2009.08.065

* Corresponding author. Tel.: +1 (306) 585 4094; faE-mail address: t.viraraghavan@uregina.ca (T. Vira

Water consumption in a fish-processing industry and high-strength wastewater from such an industryare of great concern world-wide. Liquid effluent regulations are becoming more stringent day by day. Bio-logical treatment is the best option for such a wastewater. Anaerobic processes such as upflow anaerobicsludge blanket (UASB) reactor, anaerobic filter (AF) and anaerobic fluidized bed (AFB) reactor can achievehigh (80–90%) organics removal and produce biogas. Aerobic processes such as activated sludge, rotatingbiological contactor, trickling filter and lagoons are also suitable for organics removal. Anaerobic diges-tion followed by an aerobic process is an optimal process option for fish processing wastewatertreatment.

� 2009 Elsevier Ltd. All rights reserved.

1. Introduction

Global consumption of fish has doubled since 1973, and thedeveloping world has been responsible for nearly all of this growth.The total per capita consumption of food fish in the developingworld has increased from 7.3 kg/capita/year to 14.0 kg/capita/yearfrom 1973 to 1997 while it has come down from 22.6 kg/capita/year to 21.7 kg/capita/year from 1973 to 1997 in the case of thedeveloped world. The projected per capita consumption of foodfish in the year 2020 are estimated to be 16.2 kg/capita/year and21.5 kg/capita/year for the developing world and developed world,respectively (Delgado et al., 2003). Countries with rapid populationgrowth, rapid income growth, and urbanization tend to have thegreatest increases in consumption of fish products. Because mostwild fisheries are near their maximum sustainable exploitationlevels, production from these fisheries will likely grow only slowlyto 2020. People in the developing world will increase their totalconsumption of food fish, whereas total consumption is likely toremain static in the developed world. Even under the ecologicalcollapse scenario, global per capita consumption declines only bya small amount—from 17.1 kg per year under the baseline scenarioto 14.2 kg (Delgado et al., 2003).

Canada possesses the world’s longest coastline (244,000 km),representing 25% of the entire coastline in the world (Agricultureand Agri-Food Canada (AAFC), 2003). The capture fishing industryoperates in three broad regions (Atlantic, Pacific and freshwater)in Canada. Canada exports over 75% of its fish and seafood prod-

ll rights reserved.

x: +1 (306) 585 4855.raghavan).

ucts to more than 80 countries (AAFC, 2003). The main categoriesof fish involved are groundfish, herring, salmon, and shellfish.There are a few other countries such as China, Thailand, Indiaand Sweden where the fishery sectors (catching and processing)contribute significantly to the national gross domestic product(GDP). The total net change in exports from 1973 to 1997 was465 thousand tonne for China and 231 thousand tonne for India(Delgado et al., 2003).

The fish processing schemes in terms of raw material, source ofutility water, and unit processes vary between plants. The commonprocesses in fish processing plants are filleting, freezing, drying,fermenting, canning and smoking (Palenzuela-Rollon, 1999). Simi-lar to most processing industries, fish processing operations pro-duce wastewater, which contains organic contaminants insoluble, colloidal and particulate form. Depending on the particularoperation, the degree of contamination may be small (e.g., washingoperations), mild (e.g., fish filleting), or heavy (e.g., bloodwaterdrained from fish storage tanks). Typical flow diagrams of fish mealproduction and salmon processing are presented in Fig. 1 andFig. 2, respectively (Management of Wastes from Atlantic SeafoodProcessing Operations, 2003). In fishery wastewater the contami-nants present are undefined mixtures of mostly organic sub-stances. Again, it is difficult to generalize the extent of theproblem created by this wastewater as it depends on the effluentstrength, wastewater discharge rate and the absorbing capacityof the receiving water body (Gonzalez, 1996). During fish eviscer-ation and cooking high content of COD, nutrient, oil and fat aregenerated in fish processing wastewater (Aguiar and Sant, 1988;Mendez et al., 1992). The level of total soluble and suspendedCOD vary largely between factory and fish type.

Solids removal

Oil removal Oil polishing

Evaporation

oil to storage

water to discharge

Screen

Offal storage

Cooker Centrifuge

Vapor scrubber

Press Cookers Drier

steamnon-oily species

bloodwater

water discharge

water to discharge

water gas to atmosphere

water to discharge

bagging or storage

dry conveying wet conveying

oily species

solids

condenser water to discharge

solubles to market

stickwater discharge

pressliquor

Fig. 1. Flow diagram for fish meal production (adapted from Riddle and Shikaze, 1973).

440 P. Chowdhury et al. / Bioresource Technology 101 (2010) 439–449

The fish and shellfish processing industries are facing problemsof waste handling and disposal, plant sanitation, raw materialavailability and cost, production efficiency, increased competition,and increasing labor and energy costs. As well, pollution preven-tion regulations applicable to these industries could become morestringent in coming years (Table 1). Given these challenges, costeffective solutions for waste handling and operations must befound for plants to remain in business (AAFC, 2003).

To cope with the fish processing operation liquid effluent guide-lines and more stringent standards (provincial or local govern-ment), the high strength fish processing wastewater should betreated through a good waste management and treatment technol-ogy. This review attempts to identify the latest trends in biological

treatment technology (aerobic and anaerobic) in the fish-process-ing industry.

2. Characterization of wastewater from fish processing plants

The volume and concentration of wastewater from fish process-ing depends mainly on the raw fish composition, additive used,processing water source and the unit process. The main compo-nents of fish processing wastewater are lipids and protein(Gonzalez, 1996). A summary of contaminant concentrations ineffluent from different fish processing plants is presented in Table2. Despite the substantial variation in results, these data provide a

wastewater streams

Grazing

Packing/Shipping

Freezing

Milt washing and freezing

Packaging shipping

Offal hopper Collection sump

chilled wateroffal

water

wasted milt

Packing and fishing vessels

Vessel unloading with wet pump

Conveyors

Roe washing/Curing

Dressing for freezing

Intermediate storage

Packaging shipping

vessel-hold water

recirculation

salmon and vessel-hold water

salmon

rinse water

chilled water

rinse water

brinecuredroe

used brine

dressed salmon

roe

milt

Fig. 2. Flow diagram for salmon dressing for freezing (adapted from NovaTec, 1994).

P. Chowdhury et al. / Bioresource Technology 101 (2010) 439–449 441

useful guideline for wastewater treatment system design and actas a starting point for waste minimization.

2.1. pH

Effluent pH from fish processing plants is usually close to neu-tral. The results obtained from four different fisheries from BritishColumbia showed pH in the range of 5.7–7.4 with an average pH of6.48 (Technical Report Series FREMP, 1994). During the productionof fish meal, fish condensate is produced where pH range from 9 to10. Ammonia emission and proteinaceous matter decomposition ismostly pH dependent (Gonzalez, 1996).

2.2. Solids content

Suspended solids may affect the aquatic life by reducing theamount of light that enters into water. According to different fish-eries in British Columbia, the effluent total solids concentrations

were generally high (2000–3000 mg/L). Total suspended solids(TSS) accounts for approximately 10–30% of total solids (TS)(Technical Report Series FREMP, 1994). In general, fish processingwastewater contains high levels of suspended solids which aremainly proteins and lipids (Palenzuela-Rollon et al., 2002). In thecase of salmon, bottomfish, halibut, redfish and tuna the TSS werein the range of 100–1000 mg/L. Carawan et al. (1979) observed thatin tuna processing the average value of total solids was 17,900 mg/L of which 40% was organic. The fish condensate has high volatilesolids (VS) consisting of trimethyl amine (TMA) and volatile fattyacids (VFA). The wastewater characteristics from fish processingunits depend on the composition of raw fish, the unit processes,source of processing water and additives used such as brine, oilfor the canning process (Palenzuela-Rollon, 1999).

2.3. Organic content

In a fish processing wastewater, BOD5 originates primarily fromcarbonaceous compounds and nitrogen containing compounds

Table 1Effluent guidelines for selected fish processing (adapted from US EPA, 2008).

Type of processing Provision Effluent characteristics Effluent limitations

Maximum for any 1 day Average of daily values for 30consecutive days shall not exceed

kg/1000 kg of seafood

Alaskan mechanized salmon processing A (existing source) TSS 44 26Oil and grease 29 11pH 6–9 6–9

B (new source) TSS 42 25Oil and grease 28 10pH 6–9 6–9

Alaskan hand-butchered salmon processing A (existing source) TSS 2.6 1.6Oil and grease 0.31 0.19pH 6–9 6–9

B (new source) TSS 2.3 1.4Oil and grease 0.28 0.17pH 6–9 6–9

West coast mechanized salmon processing A (existing source) TSS 44 26Oil and grease 29 11pH 6–9 6–9

B (new source) BOD5 62 38TSS 13 7.6Oil and grease 4.2 1.5pH 6–9 6–9

West coast hand-butchered salmon processing A (existing source) TSS 2.6 1.6Oil and grease 0.31 0.19pH 6–9 6–9

B (new source) BOD5 2.7 1.7TSS 0.7 0.42Oil and grease 0.045 0.026pH 6–9 6–9

Tuna processing A (existing source) TSS 8.3 3.3Oil and grease 2.1 0.84pH 6–9 6–9

B (new source) BOD5 20 8.1TSS 7.5 3.0Oil and grease 1.9 0.76pH 6–9 6–9

Alaskan bottom fish A (existing source) TSS 3.1 1.9Oil and grease 4.3 0.56pH 6–9 6–9

B (new source) TSS 1.9 1.1Oil and grease 2.6 0.34pH 6–9 6–9

442 P. Chowdhury et al. / Bioresource Technology 101 (2010) 439–449

(protein, peptide and volatile amines). In a fish possessing industry,the effluent COD is usually higher than BOD5. A review of literatureshowed that wastewater from fish processing operations has highBOD5 and COD. No information is available in the literature to ex-plain if BOD5 values include nitrification. Most of the BOD5 usuallycomes from hold water and from the butchering process (TechnicalReport Series FREMP, 1994). Fish canning industries have a highconcentration of organic polluting substances in the range of10,000–50,000 mg/L (Mendez et al., 1995). The wastewater gener-ated during fish meal production is known to bear an extremelyhigh organic load. The wastewater produced by the washing of sur-imi has also been known to have fairly high organic load. The char-acteristics of the wastewater are found to be greatly affected by theraw materials used in the processing plants (Omil et al., 1996). Thequality of the raw materials to be processed has also been found tovary as a function of time (Omil et al., 1996). The high-strengthwastewaters such as the one generated during fish meal produc-tion are often known to be diluted with cooling waters from theoverall process, prior to disposal (Alfonso and Borquez, 2002).The ratio of process water to product is one of the major factorsinfluencing the organic content of the fish-processing effluent.The wide range of data for organic content of the effluent for a gi-

ven species/process (Table 2) could be due to variation in the ratiosof process water to product, the type and quality of raw materialsused in different processing units.

Effluent BOD5:COD ratios varied widely within and among pro-cessing plants ranging from 1.1:1 to 3:1 (Technical Report SeriesFREMP, 1994). Carawan et al. (1979) observed that the BOD5

(500–1500 mg/L) of tuna waste was only 40% of the COD (1300–3250 mg/L) value. As reported by del Valle and Aguilera (1990) fishmeal blood water contributed the highest COD value (93,000 mg/L)among all the processes.

2.4. Fat, oil and grease (FOG)

Fat, oil and grease (FOG) are also important parameters of fishprocessing wastewater. Around 60% of the oil and grease originatesfrom the butchering process (NovaTec, 1994). The rest of the oiland grease is generated during fish canning and fish processingoperations (Gonzalez, 1996). The FOG should be removed fromwastewater because it usually floats on the water’s surface and af-fects the oxygen transfer to water. Carawan et al. (1979) reportedthe FOG values for herring, tuna, salmon and catfish processing

Table 2Characteristics of fish processing plant effluents.

Fish processed pH BOD (mg/L) COD (mg/L) TSS (mg/L) FOG (mg/L) TKN (mg/L) References

Bottom fish 192–1726 – 300 – Riddle and Shikaze (1973)Catfish processing 400 200 Carawan (1991)Fish canning 1400 2900 1900 82 NovaTec (1994)Fish canning 6.4 1733 3320 Total solids 5985 1002 207 Prasertan et al. (1994)Fish cannery (Herring brine) 3.8 78,000 90,000 10,000 4000 3000 Balslev-Olesen et al. (1990)Fish condensate 9–10 Total NH3

2000Sandberg and Ahring (1992)

Fish freezing 6.9 814 1472 Total solids 4998 662 126 Prasertan et al. (1994)Fish processing 3500 326–1432 918–1000 117 del Valle and Aguilera (1990)Fish processing 77–268 AAFC, 2003Fish processing 5.8 11,874 46,955 Total solids 6259 2822 456 Prasertan et al. (1994)Fish processing wastewater 6–7 Najafpour et al. (2006)Fish salting 2300 5400 6000 257 NovaTec (1994)Fish smoking 1700 – 400 77 NovaTec (1994)Fisheries, British Columbia 5.7–7.4 128–2680 316–3460 2000–3000 Tech Report Series, FREMP

(1994)Halibut 145–420 – 95–245 – Riddle and Shikaze (1973)Herring (filleting) 3200–5600 6255 1150–5310 – Riddle and Shikaze (1973)Herring processing 1200–6000 3000–

10,000600–5000 60–800 Carawan (1991)

Mussel cooking 18,500 Total solids 1400 Mendez et al. (1992)Non-Alaskan bottom fish plant 6.89 Carawan et al. (1979)Redfish 40–114 – 14–101 – Riddle and Shikaze (1973)Salmon 397–3082 – 40–1824 – Riddle and Shikaze (1973)Salmon processing 250–2600 300–5500 120–1400 20–550 Carawan (1991)Squid processing 1000–5000 Park et al. (2001)Surimi – 6400–18000 – 740–1100 Green et al. (1984)Surimi processing plant 1500–2000 Okumura and Uetana (1992)Tuna 695 – 1091 500 – Riddle and Shikaze (1973)Tuna cooking 34500 Total solids 4000 Mendez et al. (1992)Tuna pre-cooking process

wastewater6.4 7460 10582 Total solids

123752834 703 Prasertan et al. (1994)

Tuna processing 700 1600 500 250 Carawan (1991)Tuna processingWashing 1 6.4 21,400 34,723 6100 Achour et al. (2000)Washing 2 6.82 67,00 10,425 820Washing 3 6.9 2800 5551 200Cleaning 8.31 – 11361 2300Tuna 500–1500 1300–3250 Carawan et al. (1979)

‘–’ indicates that no information is available.

P. Chowdhury et al. / Bioresource Technology 101 (2010) 439–449 443

were 60–800 mg/L, 250 mg/L, 20–550 mg/L and 200 mg/L,respectively.

2.5. Nitrogen and phosphorous

Excess quantity of nitrogen (N) and phosphorus (P) may causeproliferation of algae and affect aquatic life in a water body. Forbiological treatment, a ratio of N:P of 5:1 is recommended forproper growth of the biomass (Eckenfelder, 1980; Metcalf andEddy Inc., 1979). Although N and P are normally present in the fish-eries wastewater, their concentration is minimal in most cases(Gonzalez, 1996). The high nitrogen levels are likely due to thehigh protein content (15–20% of wet weight) of fish and marineinvertebrate (Sikorski, 1990). Sometimes high ammonia concentra-tion is observed due to high blood and slime content in wastewaterstreams. As reported by a few fish processing plant the overall,ammonia concentration ranged from 0.7 mg/L to 69.7 mg/L(Technical Report Series FREMP, 1994). In the fish condensate thetotal ammonia content can be up to approximately 2000 mg N/L.High BOD concentrations are generally associated with highammonia concentrations (Technical Report Series FREMP, 1994).The degree of ammonia toxicity depends primarily on the totalammonia concentration and pH. Environment Canada, AtlanticRegion reported an effluent ammonia concentration of 42 mg/Lfor salmon processing and 20 mg/L for groundfish processing.

Phosphorus also partly originates from the fish, but can also beintroduced with processing and cleaning agents (Intrasungkhaet al., 1999).

3. Water management and cleaner technology

Fish processing requires large amounts of water, primarily forwashing and cleaning purposes, but also as media for storageand refrigeration of fish products before and during processing.In addition, water is an important lubricant and transport mediumin the various handling and processing steps of bulk fish process-ing. Fish processing plants generate large wastewater volumesand are frequently inefficient users of water (World Bank Group,2007). It was reported that pollution control in fish processingplants in Thailand could be achieved through water conservationand waster reuse (Achour et al., 2000). A summary of water con-sumption data from four fish processing plants in British Columbiaand wastewater discharge flows for different fish processing unitsis presented in Table 3. Average water use during different unitoperations in a gulf shrimp canning plant (Table 3) indicates thatpeelers use as much as 58.1% of the total water consumed(Carawan, 1991). Tuna processing plants were reported to havewastewater discharges as high as 13627.4 m3/d (3600,000 gpd).In canning of tuna, the wastewater is generated from fish thawing,washing, and eviscerating, cooling and washing of fish and cansafter pre-cooking and cooking, and clean-up of washing areas

Table 3Water consumption and wastewater discharge in fish processing plants.

Fish processing Plant Reference

Average water consumptionBritish Columbia Packers Ltd. 115 m3/tonne Technical Report Series FREMP (1994)Bella Coola 4 m3/tonne Technical Report Series FREMP (1994)Lion’s Gate Fisheries Ltd. 13 m3/tonne Technical Report Series FREMP (1994)Ocean Fisheries Ltd. 36 m3/tonne Technical Report Series FREMP (1994)

Gulf shrimp canningPeelers 58.1% Carawan (1991)Washers 8.8%Separators 6.9%Blancher 1.6%De-icing 4.2%Cooling 12.1%Washdown 8.3%

Wastewater dischargeSalmon

Large processing plant 3.12 L/kg (374 gal/1000 lb) Carawan (1991)Small processing plant 9.898 L/kg (1186 gal/1000 lb)

Tuna processing plants 13627.4 m3 (3600,000 gpd) Carawan (1991)Bottom fish 22.71–1514.2 m3 (6000–400,000 gpd) Carawan (1991)Fish meal plants 37.854–348.257 m3 (10,000–92,000 gpd) Carawan (1991)Finfish 0.9179 L/kg (110 gal/1000 lb) Carawan (1991)Canning of tuna and sardine 14–22 m3/tonne Palenzuela-Rollon (1999)

444 P. Chowdhury et al. / Bioresource Technology 101 (2010) 439–449

(Palenzuela-Rollon, 1999). Very high water consumption occurswhen the amount of processed fish is low. It can be seen from Table3 that large salmon processing plants discharge 3.1211 L/kg(374 gal of wastewater/1000 lb) while small salmon processingplants discharge 9.8976 L/kg (1186 gal of wastewater/1000 lb fish).High water consumption may also be due to high base line waterconsumption. The highest and lowest recorded water consumptionin fish processing plants in British Columbia was 228 m3/tonne and2.9 m3/tonne respectively (Technical Report Series FREMP, 1994).Water consumption in Japanese fish factories range from 15.02L/kg to 50.07 L/kg (1800 gal/1000 lb to 6000 gal/1000 lb) for thevarious types of plants. It has been reported that water use insurimi processing was 25 times the throughput. Thus, water useis 25.036 L/kg fish or 227.83 L/kg surimi (3000 gal/l000 lb fish or27,300 gal/l000 lb surimi) (Carawan, 1991). Wastewater from fishprocessing and industrial fisheries is very diverse. Each plant isunique so generalizations about water use and wastewater charac-teristics are difficult (Carawan, 1991).

As water is used extensively in fish processing, water savingmeasures are very common cleaner-production opportunities inthis industry. The first step in reducing water consumption is toanalyze water use patterns carefully to identify leaks and wastefulpractices and ways to address them and determine optimum waterconsumption rate necessary to maintain process operations andfood hygiene standards. Once water use for essential operationshas been optimized, water reuse can be considered without com-promising product quality and hygiene.

There are many areas in fish processing plant in which the useof water can be minimized by systemic way. One of the first water-saving techniques employed should be to eliminate the extensiveuse of flumes for in-plant transport of product. This techniquewas applied at one plant whose water consumption was reducedfrom over 32.226 m3 water/m3 of fish to 10.742 m3 water/m3 offish (300 gal/bushel of fish to about 100 gal/bushel of fish). Manyplants are now using pneumatic ducts rather than flumes for mov-ing small particles, dry material such as shell, and wet screenedsolids. Spring-loaded hose can be used for water saving whichautomatically shuts off when released by the user. Much morewater is being used in the average butchering operation than isnecessary (Carawan et al., 1979). Wastewater reuse basically in-volves collecting the effluent from one or more unit processes,

and then using that effluent as the influent for other unit processes.The main factor in wastewater reuse lies in matching the effluentfrom one unit process with the influent requirements of anotherunit process. The matchmaker must be careful to take into accountthe effluent’s quantity and quality when examining the sourcerequirements of prospective processes (Carawan et al., 1979). Thefood industry presents limited opportunities for recycling due tothe stringent cleanliness required. It is conceivable that wastewa-ter could be cleaned up sufficiently to be used for a non foodcontact use, such as cooling water (McDonald et al., 1999). Consid-eration and demonstration of the technical feasibility of the reuseof municipal wastewater as potable water has occurred inSouth Africa (Kfir and Slabbert, 1991) and several US cities(Rogers and Lauer, 1991). The safety and public health issuesinvolved have been widely discussed, but generally pipe-to-pipepotable reuse is not favored and most schemes in use involve anatural intermediate step (i.e. aquifer, reservoir) (Johns, 1995).

4. Biological treatment processes

After suitable primary treatment the wastewater is treatedthrough a biological wastewater treatment system where microor-ganisms are involved in degradation of organic matter. Types ofbiological systems used in treating fish processing wastewaterare provided in Table 4.

4.1. Anaerobic processes

Anaerobic treatment converts the organic pollutants (COD,BOD5) in wastewater into a small amount of sludge and a largeamount of biogas (methane and carbon dioxide), while leavingsome pollution unresolved. The main advantages, particularly forbigger plants, are (i) low operating costs, (ii) low space require-ments, (iii) valuable biogas production, and (iv) low sludge produc-tion. Anaerobic systems are well suited to the treatment of fishprocessing wastewater because a high degree of BOD5 removalcan be achieved at a significantly lower cost than comparable aer-obic systems and generate a smaller quantity of highly stabilized,and more easily dewatered, sludge. Furthermore, the methane-richgas which is generated can be captured for use as a fuel (Johns,1995).

Table 4Performance of aerobic and anaerobic systems for fish processing wastewater treatment.

Process Fish-processingindustry

Raw wastewatercharacteristics(mg/L)a

Organic loading Organic removal Remarks Reference

AerobicActivated sludge Fish-processing

industry0.5 kg BOD5/m3 d 90–95% BOD5 Detention time

1–2 d; F/M 0.1–0.3;Sludge age 18–20 days

Carawan et al.(1979)

Rotating biological contactor Fish cannery pH 6–7; COD6000–9000;BOD 5100; TSS 2000;TKN 750

0.018–0.037 kgCOD/m2 d

85–98% COD HRT 48 d; effluentTSS 290 mg/L

Najafpour et al.(2006)

Trickling filter Squid processing BOD 2–3000 0.08–0.4 kg BOD5/m3 d

80–87% BOD5 Park et al. (2001)

Aerated lagoon Fish-processingindustry

– 90–95% BOD5 Retention time2–10 d;ponds 2.4–4.6 mdeep

Carawan et al.(1979)

AnaerobicAnaerobic fluidized bed reactor Fish cannery

(Herring brine)COD 90000;BOD 78000;oil/fat 4000;total N 3000;SS 10,000; pH 3.8

6.7 kg COD/m3 d 88% COD Balslev-Olesenet al. (1990)Anaerobic fixed filter 4.7 kg COD/m3 d 85% COD

Anaerobic filter Seafood processing 0.3–0.99kg COD/m3 d

78–84% COD HRT 36 days Prasertsan et al.(1994)

SeafoodprocessingTunacondensate

Volatile acids 3340 1.67 kg COD/m3 d 60% COD OLR 2.0 kg COD/m3 dinitiated systemfailure

Anaerobic digester Tuna cooking COD 34,500; TS 4000;Cl� 14 g/L

4.5 kg COD/m3 d 80% COD

Mussel cooking COD 18,500TS1400Cl- 13 g/L

4.2 kg COD/m3 d 75–85% COD HRT 5 d Mendez et al.(1992)

Anaerobic fixed film Tuna processingindustry

2 kg COD/m3 d 75% COD Veiga et al.(1991)

Upflow anaerobic sludge blanketreactor

Mixed sardine andtuna canning

COD 2718 ± 532;lipids 232 ± 29; TKN410 ± 89; pH 7.2–7.6

1–8 kg COD/m3 d 80–95% COD HRT 7.2 ± 2.8 h,61 ± 17%/CODconversion tomethane

Palenzuela-Rollon et al.(2002)

Integrated bioprocessPhysical

pretreatment + anaerobicdigester + activated sludgebioreactor

Tuna processing pH 6.96; TSS 1575;COD 5553;BOD 3300;TKN 440;f at 1450

1.2 kg COD/m3 d 85–95% COD Achour et al.(2000)

a Values in mg/L except pH.

P. Chowdhury et al. / Bioresource Technology 101 (2010) 439–449 445

4.1.1. Anaerobic fixed-bed and fluidized bed reactorsBalslev-Olesen et al. (1990) carried out pilot scale studies with a

fish cannery wastewater using an anaerobic filter (AF) reactor andan anaerobic fluidized bed (AFB) reactor. The details of organicloading rate and COD reduction are given in Table 4. It was ob-served that with reduction in temperature the COD reductiondropped along with a reduction in gas production. It was con-cluded that with a proper control system and a sufficiently longstarting period, the anaerobic bio-film reactor was robust with agood performance and low operating costs. Moreover anaerobicbio-film reactors will be active for periods of more than a weekwithout an addition of organic matter (Balslev-Olesen et al., 1990).

Anaerobic filter treatment of fishery wastewater and tuna con-densate was conducted by Prasertsan et al. (1994). The organicloading rate (OLR) and hydraulic retention time (HRT) were variedduring the study. Organic loading rates have a great influence onthe biodegradation of organic matter in the wastewater, reflectedin the biogas productivity and the profiles of pH and volatile fattyacids. The highest COD reduction (84%) was obtained for fisherywastewater at a minimum OLR of 0.3 kg COD/m3 day and

maximum HRT of 36 days. The data showed that with increasedOLR, the COD reduction efficiency dropped. The highest loadingrate in which the system still maintained its high conversion effi-ciency (over 78% COD reduction) was 0.99 kg COD/m3 day at anHRT of 11 days. The tuna condensate contained a high content ofvolatile acids (3.34 g/L). COD reduction was maintained at 60%up to an OLR of 1.67 kg COD/m3 day and sharply decreased there-after. Biogas productivity was highest at an OLR of 1.3 kg COD/m3 day, with the pH of the effluent at 7.68. Biogas productionstopped completely at an OLR of 2.5 kg COD/m3 day.

A pilot plant study was performed by Mendez et al. (1992) onthe anaerobic treatment of wastewater from a fish-canning fac-tory. The system consisted of a predigester of 7 m3, a suspendedsludge digester of 15 m3 and a clarifier of 3 m3. Around 76–80%BOD5 removal was achieved with an OLR of 4 kg COD/m3 day.There was no requirement of additional nutrient during opera-tion. The salinity level of 15 g Cl�/L was maintained and with in-creased salinity no significant effect was observed. Veiga et al.(1991) carried out both laboratory and pilot studies to treatwastewater from a tuna processing industry in down flow

446 P. Chowdhury et al. / Bioresource Technology 101 (2010) 439–449

stationary fixed film reactor under mesophilic conditions. Boththe laboratory and pilot-scale reactors operated satisfactorily atan organic loading rate of 2 kg/m3 d and provided 75% COD re-moval efficiency.

4.1.2. Upflow anaerobic sludge blanket (UASB) reactorUpflow anaerobic sludge blanket (UASB) reactors have been ap-

plied to a wide range of industrial wastewaters, including thosecontaining toxic/inhibitory compounds (Weiland and Rozzi,1991). The process was found to be feasible for treatment ofdomestic wastewater with temperature as low as 14–16 �C andeven lower (Lettinga et al., 1980). According to Palenzuela-Rollonet al. (2002) the application of UASB system was a promising treat-ment option for fish processing wastewater. They determined theperformance of USAB reactor for the treatment of mixed sardineand tuna canning effluent at varying lipid levels. They mentionedthat at low lipid level (203–261 mg/L, 9% of total COD) approxi-mately 78 ± 8% COD removal and 61 ± 17% COD conversion tomethane were achieved with an OLR of 2.3 g COD/L day and anHRT of 7.2 ± 2.8 h. In the case of high-lipid wastewater a two stepUASB was recommended where the total COD removal and conver-sion to methane were 92% and 47%, respectively. Reactor treating ahigh-lipid wastewater showed a higher sludge volume index (SVI)than that treating a low-lipid wastewater.

Punal and Lema (1999) have used a 380 m3 UASB reactor for thetreatment of fish-canning factory wastewater. The wastewater wasa mixed effluent of tuna, sardine and mussel processing. The totalalkalinity of more than 3 g CaCO3/L was maintained to operate thesystem properly and to allow the biomass to resist load shocks. AnHRT of 2 days was maintained and the OLR was varied from1 kg COD/m3 day to 8 kg COD/m3 day. The efficiency of the systemwas dependent on the nature of the wastewater. The reactor per-formance was better when the reactor treated mussel and tunacooking wastewater jointly, due to the highly degradable carbohy-drate content of mussel. They determined an optimal linear veloc-ity of 0.7 m/h at which 80–95% COD removal was achieved.

4.1.3. Effect of pH and ammonia content on anaerobic processesDuring the production of fish meal, fish condensate is produced

which has high volatile solids (VS) consisting of trimethyl amine(TMA) and volatile fatty acids (VFA). In the fish condensate the to-tal ammonia content can be up to approximately 2000 mg N/L andthe pH can be from 9 to 10. Sandberg and Ahring (1992) investi-gated the influence of high pH on anaerobic degradation of fishprocessing wastewater in a UASB reactor. According to Booneand Xun (1987) most methanogenic bacteria have optima forgrowth between pH 7 and 8, whereas VFA degrading bacteria havelower pH optima. The optimal pH for mesophilic biogas reactor is6.7–7.4 (Clark and Speece, 1971). The study of Sandberg and Ahr-ing (1992) demonstrated that fish condensate can be treated wellin a UASB reactor from pH 7.3 to 8.2. When the pH was increasedslowly to 8.0 or more 15–17% drop in COD removal occurred. Ace-tate was the only carbon source in the condensate that accumu-lated upon increasing the pH. More than 99% of VFA and TMA inprocess wastewater were degraded up to pH 7.9. It was concludedthat gradual pH increment was essential in order to achieve thenecessary acclimatization of the granules and to prevent disinte-gration of the granules and that the pH should not exceed 8.2.

Aspe et al. (2001) modeled the ammonia-induced inhibitionphenomenon of anaerobic digestion and concluded that methano-genesis was the most inhibited stage. The methanogenic activitywas reduced by the presence of high concentrations of ammoniaas a result of protein degradation during the anaerobic treatment.Ammonia inhibition was directly related to the concentration ofthe undissociated form (NH3), therefore being more important athigh pH levels. It was also reported that free ammonia (FA) inhib-

itory concentrations for mesophilic treatment have been 25–140 mg N-FA/L whereas during the thermophilic digestion of cattlemanure, higher values, 390–700 mg N-FA/L, were tolerated after aninitial acclimation period (Guerrero et al., 1997).

4.1.4. Effect of salinity on anaerobic processesFish processing industries require a large amount of salt (NaCl)

for fish conservation. The wastewater generated by a fish-process-ing industry is rich in protein-based nitrogen, organic matter andsalts. It is well known that anaerobic treatment of wastewater isinhibited by the presence of high sodium/or chloride concentra-tions. Methanogenesis is strongly inhibited by a sodium concentra-tion of more than 10 g/L (Lefebvre and Moletta, 2006). But thework of Omil et al. (1995) on fish-processing effluent using ananaerobic contact system showed that the adaptation of an activemethanogenic biomass at the salinity level of the effluent was pos-sible with a suitable strategy. The treatment of high saline waste-waters was possible in an up-flow anaerobic filter operating atloadings up to 24 kg COD/m3 day. Anaerobic digesters are usuallymore sensitive to high salinity than an activated sludge unit. AChilean team worked in particular on the anaerobic digestion offishery effluents, mainly those generated at the time of fish unload-ing. After recycling and primary treatment in order to eliminateproteins and grease the effluent, containing 4–6 kg COD/m3,1:85 kg SO�2

4 =m3 and 16.2 kg Cl�/m3, could be treated anaerobi-cally using a marine inoculum which induced specific methano-genic activity at 37 �C of 0.065 kg COD-CH4/kg of VSS/d (Aspeet al., 1997).

4.2. Aerobic processes

4.2.1. Activated sludge systemIn an activated sludge process the incoming stream is diluted in

a completely mixed system and thus it is more stable to perturba-tions, i.e., the reactor is more resistant to shock loads of BOD5 andtoxic compounds. In fishery-wastewaters the perturbations thatmay appear are peaks of concentration of organic load or flowpeaks. The flow peaks can be damped in the primary treatmenttanks (Gonzalez, 1996). The activated sludge process with biologi-cal denitrification is a popular technology satisfying stringentstandards. The activated sludge technology is dominating overthe bio-film process in the practical treatment of fish processingwastewater (Battistoni and Fava, 1995). Generally a higher oxygenavailability is required in fish processing wastewater compared toother food processing wastewater for stabilization. Dairy, fruit andvegetable wastewater require approximately 1.3 kg O2/kg BOD5,whereas fish processing wastewater requires 3 kg O2/kg BOD5

(Carawan et al., 1979). In a fish-processing industry mostlyextended aeration type activated sludge systems are used. A longaeration time is provided with a low applied organic loading. Adetention time of 1–2 days is maintained in the process. A loadingrate up to 13.6 kg (30 lb) of BOD5 can be applied daily for each28.3 m3 (1000 ft3) of aeration basin volume. Food to microorgan-ism ratios (F/M) of 0.1 to 0.3 show the best operating conditionfor this type of a system. Sludge age (solids retention time) shouldbe maintained at 18–20 days. Temperature has a significant influ-ence on the performance of the extended aeration system sincepin-point floc can develop and loss of biological activity willdecrease the performance efficiency of this system under cold-weather operating conditions (Carawan et al., 1979).

4.2.2. Rotating biological contactorA rotating biological contractor (RBC) is basically an attached

growth process providing the advantages of both of biological fixedfilm and partial mixing (Tay et al., 2004). As the biological growthcomes in contact with air, oxygen is absorbed by microorganisms

P. Chowdhury et al. / Bioresource Technology 101 (2010) 439–449 447

(Reynolds and Richards, 1996). RBC efficiency is affected by discrotational speed, hydraulic retention time, loading rate, disk sub-mergence and temperature. The main advantages of an aerobicRBC are (i) short hydraulic retention time (HRT), (ii) high specificsurface area, (iii) high biomass concentration, (iv) insensitivity totoxic substrate, (v) less accumulation of sloughed bio-film and par-tial mixing, (vi) low energy consumption, and (vii) operational sim-plicity. A multi stage RBC is generally suitable for a high-strengthwastewater such as wastewater from a fish-processing industry.With a three-stage laboratory scale RBC a clear relationship wasevident between the organic loading rate and COD removal effi-ciency. As OLR was increased from 18.44 g/m2 day to 36.89g/m2 day, COD removal efficiency decreased from 97.4% to 85.4%.It has been observed that the SCOD removal increased from62.7% to 93.7% relatively to rotational speed increase from 3 rpmto 11 rpm. Thus aerobic RBC with 36% submerged level and11 rpm would be effective for treating high-strength organicwastewater. In comparison with an activated sludge system theRBC reactor is better in terms of stability, MLVSS content, recyclingand energy requirement. An RBC reactor provides more stability,requires lower energy and there is no necessity of sludge recycling(Najafpour et al., 2006).

4.2.3. Trickling filterThe primary mechanism of a trickling filter is not filtering ac-

tion of fine pores but rather diffusion and microbial assimilation(Benefield and Randall, 1980). The penetration depth of substrateinto a microbial film depends on several factors such as wastewa-ter strength, wastewater flow rate, rate of substrate utilization ofbiomass and the coefficient of diffusivity of substrate molecule inthe film. Two types of media are commonly used in trickling filters,stone media and synthetic media (Gonzalez, 1996). For stone med-ia the filter depth is only 0.9–3 m (3–10 ft) whereas for syntheticmedia up to 12 m (40 ft) filter depth have been used (Benefieldand Randall, 1980). Trickling filters, utilizing plastic media in col-umns 4.5–6.0 m high, have been used in the treatment of highstrength fruit and vegetable wastes (3000–4000 mg/L BOD5). Highliquid recirculation rates and forced air circulation are used toachieve BOD5 removals up to 90%. There is limited experience asto how trickling filters will perform when treating fish and seafoodprocessing wastewaters (Carawan et al., 1979). As with all biolog-ical systems, low temperatures reduce the degrading capacity oftrickling filters. In cold areas trickling filters may be covered(Gonzalez, 1996). In Rhode Island, a company called BioProcessTechnologies used specially designed netting materials for theattachment and growth of microorganisms needed to digest andreduce organics in a fish processing wastewater. The netting mate-rial used in the BioProcess system can be characterized as a fixedfilm or attached type of biological treatment. The configurationused can either be in a submerged mode or free standing wherewastewater is trickled down through the netting material. The re-sults indicate that the trickling filter design can take loadings of upto 5.2 g BOD5/m media/day (3.5 lb BOD5/1000 ft media/day) andstill reduce the BOD5 by 87%. Upscale design of the trickling filterusing data of 15–20,000 gpd of wastewater with BOD5 in the 2–3000 mg/L range indicated that 200,000 linear feet of media in4–6 reactor tanks would be required (Park et al., 2001).

4.2.4. Aerated lagoonAerated lagoons are used where sufficient land is not available

for seasonal retention or land application and economics do notjustify an activated sludge system. Efficient biological treatmentcan be achieved by the use of an aerated lagoon system. The pondsare between 2.4 m and 4.6 m deep, with 2–10 days retention timeand achieve 55–90% reduction in BOD5 (Carawan et al., 1979). Twotypes of aerated lagoons are commonly used in fish processing

wastewater treatment either completely mixed or facultative la-goons. In completely mixed lagoons the concentration of solidsand dissolved oxygen are maintained fairly uniform and neitherthe incoming solids nor the biomass of microorganisms settle. Infacultative lagoons the upper portions are maintained aerobicwhereas the bottom undergoes anaerobic decomposition. Thepower input for aerobic lagoons is in the order of 2.5–6 W/m3

whereas it is 0.8–1 W/m3 for facultative lagoons (Gonzalez,1996). With aerated lagoons approximately 90–95% BOD5 removalefficiency can be achieved for seafood processing wastewater(Carawan et al., 1979).

4.2.5. Integrated bioprocessAchour et al. (2000) used a biodegradation system to treat the

concentrated liquid effluent from a tuna processing unit in Tuinisa.Both anaerobic and aerated bioreactors were used in the experi-ment. They used an up-flow anaerobic cylindrical fixed bed reactorfor anaerobic digestion followed by an activated sludge bioreactor.The reported COD removal of anaerobic digestion was close to 50%with a production of about 0.25 m3 CH4/kg degraded COD. The aer-ated treatment unit achieved 85% reduction of COD. The integratedsystem with physical pretreatment, anaerobic digester and aeratedbioreactor achieved 95% COD removal.

4.2.6. Effect of salinity on aerobic processIt is well known that high salinity of wastewater strongly inhib-

its the aerobic biological treatment of wastewater. There are nega-tive effects on aerobic treatment if the chloride concentrations areabove 5000–8000 mg/L. In spite of this fact, good performance ofactivated sludge system has been reported by Doudoroff (1940)and Pillai and Rajagopalan (1948). Stewart et al. (1962) reportedconsiderable BOD5 reduction due to the combined effect of highsalinity and high organic loading. In another study Kincannonand Gaudy (1968) observed that due to rapid change in salinity sol-uble COD was increased by the release of cellular material.

5. Discussion

With an increasing demand of processed fish products over theworld, the wastewater load from the fish processing sector is alsoincreasing. Fish processing wastewater mainly contains organiccontaminants in soluble, colloidal and particulate form. The organ-ic content may be very high such as 1200–6000 mg/L of BOD5 and3000–10000 mg/L of COD (e.g., herring processing) or even low like700 mg/L of BOD5 and 1600 mg/L of COD (e.g., tuna processing)depending on the fish composition and the operating process.Nitrogen and phosphorus are present in fish processing wastewa-ter in minor quantity but the suspended solids are quite high(2000–3000 mg/L). Fresh water consumption is too high in fishprocessing operations which can be reduced by applying efficientwater use strategy. Efficient water use strategies can be identifiedby first analyzing the water use patterns in the processing unit,identifying wasteful practices and by determining optimum waterconsumption rate for individual unit processes. Based on the infor-mation collected, water reuse options can be considered withoutcompromising the product quality and hygiene. Although water re-use is a good option for water conservation, it is sometimes notacceptable due to public health issues. The quality of the fish-pro-cessing effluents can be improved by reducing contact betweenprocess water and the product and ensuring high quality of theraw materials (Jacques Whitford, 2007).

In terms of wastewater treatment, several anaerobic and aero-bic processes were studied by a number of authors. Since thewastewater contains biodegradable organic matter, the potentialfor a net production of energy in the form of biogas is high. Hence

448 P. Chowdhury et al. / Bioresource Technology 101 (2010) 439–449

anaerobic treatment is an attractive option. Attached growth pro-cesses such as anaerobic fluidized bed (AFB) reactor can achievemore than 80% COD removal and it can be operated at high saltconcentration. AFB reactor is also an economically favorable op-tion. Anaerobic filter (AF) provides good COD removal; its biodeg-radation and biogas production clearly depends on organic loadingrates (OLR). A high rate anaerobic treatment system such as a UASBreactor is a promising treatment option for fish processing waste-water. More than 90% COD removal can be achieved in such a sys-tem. System pH, OLR, total ammonia content and wastewatersalinity are major factors that influence the reactor efficiency.

In a fish-processing industry extended aeration type activatedsludge processes are used because of higher oxygen requirementcompared to other food processing wastewaters. A multi stageRBC is a better treatment process than an activated sludge systemin terms of stability, MLVSS content and energy requirement.Trickling filters are rarely used for fish processing wastewater.An integrated design using anaerobic digestion followed by an aer-obic system would yield better treatment efficiency with less en-ergy consumption and reduced sludge production.

6. Summary

The common processes that contribute to the wastewater gen-eration during fish processing are drying, fermenting, canning andsmoking. Fish processing wastewaters are characterized by highBOD5 (100–3000 mg/L), COD (1000–18000 mg/L) and nitrogencontent (80–1000 mg/L). More than 80% COD removal can beachieved with anaerobic fixed filter (AF) and anaerobic fluidizedbed (AFB) reactor. Both organic loading rate (OLR) and hydraulicretention time (HRT) have influence on COD removal. A UASB reac-tor is also of advantage which provides 80–95% COD removal. Lipidand carbohydrate content of fish, greatly affects the wastewatertreatment efficiency. The optimum pH is 7.3–8.2 and optimumN-FA (nitrogen as free ammonia) is 25–140 mg/L for mesophilictreatment. High salinity (>10 g/L Na+) affects methenogenesis;salinity effect can be compensated using marine inoculums.

Fish processing wastewater can be treated by an activatedsludge extended aeration process. Aeration rate, F/M ratio, temper-ature and sludge retention time are important parameters for acti-vated sludge system performance. A multistage RBC reactor issuitable for treatment of fish processing wastewater and it is betterthan an activated sludge system providing 85–98% COD removal.Aerated lagoons provide 95% BOD5 removal. An integrated bioproc-ess with physical pretreatment, anaerobic digester and aeratedbioreactor could provide 95% COD removal efficiency.

References

Agriculture and Agri-Food Canada (AAFC), 2003. Available from: <http://ats-sea.agr.gc.ca/seafood/industry-e.htm> (accessed 20.05.2008).

Achour, M., Khelifi, O., Bouazizi, I., Hamdi, M., 2000. Design of an integratedbioprocess for the treatment of tuna processing liquid effluents. ProcessBiochem. 35, 1013–1017.

Aguiar, A.L.C., Sant Jr., G.L., 1988. Liquid effluents of the fish canning industries ofRio de Janeiro State, Treatment alternatives. Environ. Tech. Lett. 9, 421–428.

Alfonso, O.M.D., Borquez, R., 2002. Review of the treatment of seafood processingwastewaters and recovery of proteins therein by membrane separationprocesses – prospects of the ultrafiltration of wastewaters from the fish mealindustry. Desalination 142, 29–45.

Aspe, E., Marti, M.C., Roeckel, M., 1997. Anaerobic treatment of fishery wastewaterusing a marine sediment inoculum. Water Res. 31 (9), 2147–2160.

Aspe, E., Marti, M.C., Jara, A., Roeckel, M., 2001. Ammonia inhibition in the anaerobictreatment of fishery effluents. Water Environ. Res. 73 (2), 154–164.

Balslev-Olesen, P., Lynggaard-Jensen, A., Nickelsen, C., 1990. Pilot-scale experimentson anaerobic treatment of wastewater from a fish processing plant. Water Sci.Technol. 22 (1–2), 463–474.

Battistoni, P., Fava, G., 1995. Fish processing wastewater: production of internalcarbon source for enhanced biological nitrogen removal. Water Sci. Technol. 32(9–10), 293–302.

Benefield, L.D., Randall, C.W., 1980. Biological Process Design for WastewaterTreatment. Prentice-Hall, New York.

Boone, D.R., Xun, L., 1987. Effects of pH, temperature and nutrients on propionatedegradation by a methanogenic enrichment culture. Appl. Environ. Microbiol.53, 1589–1592.

Carawan, R.E., 1991. Processing plant waste management guidelines for aquaticfishery products. Food and the Environment. Available from: <http://www.p2pays.org/ref/02/01796.pdf>. (accessed 20.05.2008).

Carawan, R.E., Chambers, J.V., Zall, J.V., 1979. Seafood Water and WastewaterManagement. North Carolina Agricultural Extension Services, Raleigh, NC.

Clark, R.H., Speece, R.E., 1971. The pH tolerance of anaerobic digestion. Adv. WaterPollut. Res. 1, 1–14.

del Valle, J.M., Aguilera, J.M., 1990. Recovery of liquid by-products from fish mealfactories: a review. Process Biochem. Int. 25 (4), 122–131.

Delgado, C.L., Wada, N., Rosegrant, M.W., Meijer, S., Ahmed, M., 2003. The Future ofFish: Issue and Trend to 2020 (Issue Brief). International Food Policy ResearchInstitute (Washington, DC) and the World Fish Center (Penang, Malaysia).

Doudoroff, M., 1940. Experiments on the adaptation of E. Coli to sodium chloride. J.Gen. Physiol. 23, 585–590.

Eckenfelder, W.W., 1980. Principles of Water Quality Management. CBI PublishingCo., Boston, USA.

Gonzalez, J.F., 1996. Wastewater Treatment in the Fishery Industry. FAO FisheriesTechnical Paper (FAO), No. 355/FAO, Rome (Italy), Fisheries Dept.

Green, D., Tzou, L., Chao, A.C., Lanier, T.C., 1984. Strategies for handling solublewastes generated during minced fish (surimi) production. In: Proceedings of the39th industrial waste conference, May 8–10, 1984. Purdue University, WestLafayett, Indiana, pp. 565–572.

Guerrero, L., Omil, F., Mthdez, R., Lema, J.M., 1997. Treatment of saline wastewatersfrom fish meal factories in an anaerobic filter under extreme ammoniacalconcentrations. Bioresour. Technol. 61, 69–78.

Intrasungkha, N., Keller, J., Blackall, L.L., 1999. Biological nutrient removal efficiencyin treatment of saline wastewater. Water Sci. Technol. 39 (6), 183–190.

Jacques Whitford, 2007. Environmental audit at Natures Sea Farms Inc. St. Albansprocessing plant. Final report produced to Fisheries and Oceans Canada, pp. 1–22.

Johns, M.R., 1995. Developments in wastewater treatment in the meat processingindustry: a review. Bioresour. Technol. 54, 203–216.

Kfir, R., Slabbert, J.L., 1991. Health aspects of wastewater reclamation for potableuse. In: Proceedings of the Symposium on Water Supply & Water Reuse: 1991and Beyond. AWRA, Bethesda, MD, pp. 381–390.

Kincannon, D.F., Gaudy, A.F., 1968. Response of biological waste treatment systemsto changes in salt concentrations. Biotechnol. Bioeng. 10, 483–496.

Lefebvre, O., Moletta, R., 2006. Treatment of organic pollution in industrial salinewastewater: a review. Water Res. 40, 3671–3682.

Lettinga, G., Hobma, S.W., Klapwijk, A., Van Velsen, A.F.M., de Zeeuw, W.J., 1980. Useof the Upflow Sludge Blanket (USB) reactor concept for biological wastewatertreatment. Biotechnol. Bioeng. 22, 699–734.

Management of Wastes from Atlantic Seafood Processing Operations, 2003. AMECEarth & Environmental Limited 32 Troop Ave, Unit #301 Dartmouth, NovaScotia B3B 1Z1.

McDonald, C., Ince, M.E., Smith, M.D., Dillon, M., 1999. Fish processing in Uganda:waste minimization. In: 25th WEDC Conference on Integrated Development forWaste Supply and Sanitation. Addis Ababa, Ethiopia.

Mendez, R., Omil, F., Soto, M., Lema, J.M., 1992. Pilot plant studies on the anaerobictreatment of different wastewater from a fish-canning factory. Water Sci.Technol. 25 (1), 37–44.

Mendez, R., Lema, J.M., Soto, M., 1995. Treatment of seafood-processingwastewaters in mesophilic and thermophilic anaerobic filters. Water Environ.Res. 67, 33–45.

Metcalf and Eddy Inc., 1979. Waste-water Engineering: Treatment, Disposal, Reuse.McGraw-Hill Book Co., New York, USA.

Najafpour, G.D., Zinatizadeh, A.A.L., Lee, L.K., 2006. Performance of a three-stageaerobic RBC reactor in food canning wastewater treatment. Biochem. Eng. J. 30,297–302.

NovaTec Consultants Inc. and EVS Environmental Consultants, 1994. WastewaterCharacterization of Fish Processing Plant Effluents – A Report to Water Quality/Waste Management Committee. Fraser River Estuary Management Program.Available from: <http://www.rem.sfu.ca/FRAP/9339.pdf> (accessed on20.05.2008).

Okumura, A., Uetana, K., 1992. Treatment of fish processing wastes in Japan.Industry Environ. 15 (1–2), 34–39.

Omil, F., Mendez, R., Lema, J.M., 1995. Anaerobic treatment of saline wastewatersunder high sulphide and ammonia content. Bioresour. Technol. 54 (3), 269–278.

Omil, F., Mendez, R., Lema, J.M., 1996. Anaerobic treatment of seafood processingwaste waters in an industrial anaerobic pilot plant. Water S.A. 22 (2), 173–181.

Palenzuela-Rollon, A., 1999. Anaerobic Digestion of Fish Processing Wastewaterwith Special Emphasis on Hydrolysis of Suspended Solids. Taylor and Francis,London.

Palenzuela-Rollon, A., Zeeman, G., Lubberding, H.J., Lettinga, G., Alaerts, G.J., 2002.Treatment of fish processing wastewater in a one- or two-step upflowanaerobic sludge blanket (UASB) reactor. Water Sci. Technol. 45 (10), 207–212.

Park, E., Enander, R., Barnett, M.S., Lee, C., 2001. Pollution prevention andbiochemical oxygen demand reduction in a squid processing facility. J.Cleaner Product. 9, 341–349.

Pillai, S.C., Rajagopalan, R., 1948. Influence of sea water on protozoa activity andpurification of sewage by the activated sludge. Curr. Sci. 17, 329.

P. Chowdhury et al. / Bioresource Technology 101 (2010) 439–449 449

Prasertsan, P., Jung, S., Buckle, K.A., 1994. Anaerobic filter treatment of fisherywastewater. World J. Microbiol. Biotechnol. 10, 11–13.

Punal, A., Lema, J.M., 1999. Anaerobic treatment of wastewater from a fish-canningfactory in a full-scale upflow anaerobic sludge blanket (UASB) reactor. WaterSci. Technol. 40 (8), 57–62.

Reynolds, T.D., Richards, P.A., 1996. Unit Operations and Process in EnvironmentalEngineering, second ed. PWS Publishing Company, Boston.

Riddle, M.J., Shikaze, K., 1973. Characterization and treatment of fish processingplant effluents in Canada. Food Processing Waste Management; Syracuse, NewYork. Ithaca. New York, Cornell University. pp. 274–305.

Rogers, S.E., Lauer, W.C., 1991. The demonstration of direct potable reuse. In:Proceedings of the Symposium on Water Supply & Water Reuse: 1991 andBeyond. AWRA, Bethesda, MD, pp. 371–379.

Sandberg, M., Ahring, B.K., 1992. Anaerobic treatment of fish meal processwaste-water in a UASB reactor at high pH. Appl. Microbiol. Biotechnol. 36,800–804.

Sikorski, Z., 1990. Seafood Resources: Nutrient Composition and Preservation. CRCPress Inc., Boca Raton.

Stewart, M.J., Ludwig, H.F., Kearns, W.H., 1962. Effects of varying salinity on theextended aeration process. J. Water Pollut. Control Fed. 34, 1161–1177.

Tay, J.-H., Show, K.-Y., Hung, Y.-T., 2004. Seafood processing wastewater treatment.In: Wang, L., Hung, Y.-T., Lo, H., Yapijakis, C. (Eds.), Handbook of Industrial andHazardous Wastes Treatment, second ed. Marcel Dekker, Inc., New York, pp.647–684.

Technical Report Series FREMP WQWM-93-10, DOE FRAP 1993-39, 1994.Wastewater Characterization of Fish Processing Plant Effluents. Fraser RiverEstuary Management Program. New West Minister, B. C.

US EPA, 2008. Electronic code of federal regulations (e-CFT), Parts 400-424. USEnvironmental Protection Agency, Washinton, DC.

Veiga, M.C., Mendez, R.J., Lema, J.M., 1991. Treatment of tuna processingwastewater in laboratory and pilot scale DSFF anaerobic reactors. In:Proceedings of the 46th industrial waste conference, May 14–16, 1991.Purdue University, West Lafayett, Indiana, pp. 447–453.

Weiland, P., Rozzi, A., 1991. The start-up, operation and monitoring of high rateanaerobic treatment systems: discusser’s report. Water Sci. Technol. 24 (8),257–277.

World Bank Group. International Finance Corporation, 2007. Environmental,Health and Safety Guidelines for Fish Processing. Washington, DC20433, USA. Available from: <http://www.ifc.org/ifcext/enviro.nsf/Content/EnvironmentalGuidelines>.