Quality and treatability of seafood processing wastewater using coagulation – flocculation

Introduction: Seafood processing wastewater, which contain high concentrations of pollutants discharged to receiving waters, will reduced the quality of these water resources. The present study was conducted to assess the quality and treatability of wastewater result from fish market in Bandar Abbas using coagulation – flocculation process. Methods: This research was a cross sectional study. In this study 12 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, BOD5, pH, TP, TKN and FOG. In this study, 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 the SPSS 15 software. Results: The results of this study revealed that BOD5, COD, TSS, FOG, TKN and TP were 1200 mg/L, 1760 mg/L, 330 mg/L, 280 mg/L, 104 mg/L and 45.8 mg/L, respectively. These indices were 46, 28, 8, 18, 24 and 2 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 150-17mg/L, the efficiency on COD removal was 75%-90%, the optimum dose of ferric chloride 200-250mg/L, efficiency was 70%-90%, ferrous sulfate with 250-300mg/L, efficiency was 80%-90%, alum with optimal dose 250-300mg/L, efficiency was 60%-70%. Optimum pH values for poly aluminum chloride, ferric chloride, ferrous sulfate and alum were 6-7, 5-6, 5-7 and 5-6, respectively. Conclusion: In order to prevent pollution of coastal waters of Persian Gulf with wastewater originated from fish market of Bandar Abbas, it essential to treat this wastewater. Based on the findings of this study, using coagulation – flocculation process can significantly reduce the COD of wastewater. But it seems that in choosing the appropriate type and dose of coagulants and optimum pH, environmental considerations is important.