Quality and treatability of seafood processing wastewater using coagulation –flocculation method

Introduction: Seafood processing wastewater, containing high concentrations of pollutants discharged to receiving waters, will reduce the quality of water resources. The present study was conducted to assess the quality and treatability of wastewater of fish market in Bandar Abbas using coagulation – flocculation process. Methods: In this cross-sectional study, ۱۲ composite sample of wastewater from the fish market in Bandar Abbas were selected randomly. Variables to assess the quality of the effluent were TSS, COD, BOD۵, pH, TP, TKN and FOG. Using jar test apparatus, appropriate coagulant was chosen. Then coagulant dose and pH were optimized. Data analyses based on measures of central tendency dispersion were performed using SPSS Software. Results: The results of this study revealed that BOD۵, COD, TSS, FOG, TKN and TP were ۱۲۰۰ mg/L, ۱۷۶۰ mg/L, ۳۳۰ mg/L, ۲۸۰ mg/L, ۱۰۴ mg/L and ۴۵.۸ mg/L, respectively. These indices were ۴۶, ۲۸, ۸, ۱۸, ۲۴ and ۲ times respectively greater than the maximum allowable concentration levels for industrial wastewater discharge to receiving waters. Also based on the results, poly aluminum chloride at the optimum dose of ۱۵۰-۱۷mg/L, the efficiency on COD removal was ۷۵%-۹۰%, the optimum dose of ferric chloride ۲۰۰-۲۵۰mg/L, efficiency was ۷۰%-۹۰%, ferrous sulfate with ۲۵۰-۳۰۰mg/L, efficiency was ۸۰%-۹۰%, alum with optimal dose ۲۵۰-۳۰۰mg/L, efficiency was ۶۰%-۷۰%. Optimum pH values for poly aluminum chloride, ferric chloride, ferrous sulfate and alum were ۶-۷, ۵-۶, ۵-۷ and ۵-۶, respectively. Conclusion: In order to prevent pollution of coastal waters of Persian Gulf with wastewater originated from fish market of Bandar Abbas, it is essential to treat this wastewater. Based on the findings of this study, coagulation – flocculation process can significantly reduce the COD of wastewater. It seems that in choosing the appropriate type and dose of coagulants and optimum pH, environmental considerations are important.

Keywords:

Coagulation , Flocculation , Bandar Abbas , Coagulation , Flocculation , Bandar Abbas