Statistical Analysis and Optimization of an Aerobic SBR Treating an Industrial Estate Wastewater Using Response Surface Methodology (RSM)

In this study, the performance of an aerobic sequencing batch reactor (SBR) removing carbon and nutrient (N & P) from Faraman’s industrial wastewater (FIW) was investigated. This study was performed by varying two significant independent variables viz. aeration time and biomass concentration. The experiments were conducted based on a central composite design (CCD) and analyzed using response surface methodology (RSM). The region of exploration for the process was taken as the area enclosed by aeration time (6-24 h) and mixed liquor volatile suspended solid (MLVSS) concentration (2000-7000 mg/l) boundaries. Seven dependent parameters as the process responses were measured and calculated. Direct and interactive effects of the variables on the responses were described by the models given by RSM. The results showed that the maximum total COD (TCOD) removal of 73.89% was obtained at the highest value of the factors (24 h and 7000 mg/l). The maximum values of total nitrogen (TN) removal efficiency were found to be 36.39%. The low TN removal directed the study to the reduction of oxygen level from 7 to 3 mg/l. The DO reduction with the extended aeration mode resulted in an increase in TN removal while decreased the TCOD, non-biodegradable COD (nbCOD) and BOD removal efficiencies. The oxygen concentration had diminutive effect on phosphorus removal.