Parameter optimization of ferro-sonication pre-treatment process for degradation of bisphenol A and biodegradation from wastewater sludge using response surface model

In this study, the application of response surface model in predicting and optimizing the ferro-sonication pre-treatment for degradation of bisphenol A (BPA), an endocrine disrupter compound from wastewater sludge (WWS) was investigated. The ferro-sonication pre-treatment process was carried out according to central composite design (CCD) with four independent variables such as wastewater sludge solids concentration, pH, ultrasonication time and FeSO4 concentration. The effect of ferro-sonication pre-treatment was assessed in terms of increase in sludge solids (suspended solids (SS) and volatile solids (VS)) and organic matter (chemical oxygen demand (COD) and soluble organic carbon (SOC)) solubilization and simultaneous BPA degradation from WWS. It was observed that among all the variables studied, ultrasonication time had more significantly affected the efficiency of the ferro-sonication pre-treatment process followed by FeSO4 and solids concentration. Through this optimization process, it was found that maximum BPA degradation of 88% could be obtained with 163 min ultrasonication time, 2.71 mg/L FeSO4 concentration, pH 2.81 with 22 g/L SS. Further, the effect of ferro-sonication pre-treatment on biodegradation of WWS was also studied. It was observed that ultrasonication time had significant effect and the higher biodegradation (32.48%) was observed at 180 min ultrasonication time.