PROCESS OPTIMIZATION CONDITION TREATMENT OF HIGH SALT SEAFOOD PROCESSING WASTEWATER BY RESPONSE SURFACE METHODOLOGY (RSM)

Abstract

This research aimed to using the Response surface methodology (RSM) was applied to find the optimum parameters for the treatment efficiency of seafood processing wastewater by the use of a laboratory-scale bioreactor, which is operated in anaerobic combining aerobic system. The independent variables considered were retention time, salt concentration, and activated sludge content. Optimization of parameters was performed by analysis of variance (ANOVA). Quadratic regression equation was suggested as a model for prediction of chemical oxygen demand (COD) and removal nutrients (nitrogen and phosphorus). The results indicated that with wastewater from seafood processing with the chemical input parameters of pH = 7 - 8.5, COD = 2000 mg / L, total nitrate nitrogen = 150 mg / L, NH₄⁺ = 90 mg / L, total phosphorus = 50 mg / L. In anaerobic tank, the values of optimal conditions for independent variables were obtained as follows: salt concentration (1%), the activated sludge content (8000 mg/l), the retention time (17.59 hours)  the efficiencies COD = 44.28 %, NH₄⁺=42.20% và PO₄^3-= 39.76%, with R² = 0.869 and  in aerobic tank salt concentration (1%), the activated sludge content (6642.31 mg/l), the retention time (6.95 hours) the efficiencies COD = 98.21%, NH₄⁺=94.28% và PO₄^3-= 84.64% with R² = 0.967 with the acclimatization of  7% bacteria Bacillus velezensis at high salinity. This study suggests that the parameters output wastewater was treated according to standards QCVN 11-MT:2015/BTNMT (column B).