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2 Seafood Processing Wastewater Treatment Joo-Hwa Tay and Kuan-Yeow Show Nanyang Technological University, Singapore Yung-Tse Hung Cleveland State University, Cleveland, Ohio, U.S.A. 2.1 INTRODUCTION The seafood industry consists primarily of many small processing plants, with a number of larger plants located near industry and population centers. Numerous types of seafood are processed, such as mollusks (oysters, clams, scallops), crustaceans (crabs and lobsters), saltwater fishes, and freshwater fishes. As in most processing industries, seafood-processing operations produce wastewater containing substantial contaminants in soluble, colloidal, and particulate forms. The degree of the contamination depends on the particular operation; it may be small (e.g., washing operations), mild (e.g., fish filleting), or heavy (e.g., blood water drained from fish storage tanks). Wastewater from seafood-processing operations can be very high in biochemical oxygen demand (BOD), fat, oil and grease (FOG), and nitrogen content. Literature data for seafood processing operations showed a BOD production of 1– 72.5 kg of BOD per tonne of product [1]. White fish filleting processes typically produce 12.5 –37.5 kg of BOD for every tonne of product. BOD is derived mainly from the butchering process and general cleaning, and nitrogen originates predominantly from blood in the wastewater stream [1]. It is difficult to generalize the magnitude of the problem created by these wastewater streams, as the impact depends on the strength of the effluent, the rate of discharge, and the assimilatory capacity of the receiving water body. Nevertheless, key pollution parameters must be taken into account when determining the characteristics of a wastewater and evaluating the efficiency of a wastewater treatment system. Section 2.2 discusses the parameters involved in the characterization of the seafood processing wastewater. Pretreatment and primary treatment for seafood processing wastewater are presented in Section 2.3. These are the simplest operations to reduce contaminant load and remove oil and grease from an effluent of seafood processing wastewater. Common pretreatments for seafoodprocessing wastewater include screening, settling, equalization, and dissolved air flotation. Section 2.4 focuses on biological treatments for seafood processing wastewater, namely aerobic and anaerobic treatments. The most common operations of biological treatments are also described in this section. 29 © 2006 by Taylor & Francis Group, LLC

Wastewater treatment in seafood indus. / Otpadne vode u indus. obrade ribe i morskih plodova

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