Optimization for Removal of COD and BOD through RSM-CCD by Activated Sludge Treatment Process for Pharmaceutical Wastewater

Abstract

Wastewater generated from home and commercial operations is a polluting component of water. One of the main contributors for the production of wastewater by various manufacturing processes is the pharmaceutical industry. The commercial operations of industry are causing an increase in the amount of organic and inorganic contaminants, such as total suspended solids, chemical oxygen demand (COD) and biological oxygen demand (BOD). Activated sludge process reduces COD, BOD and Total Suspended Solids (TSS), with three input variables: pH, time and Mixed Liquor Suspended Solids (MLSS). The Central Composite Design-Response Surface Methodology (CCD-RSM) is used to optimize responses for COD and BOD removal efficiency. To achieve optimization results, numerous sets of trials were conducted for the input variables - pH (4.2–6.5), time (12–30 h) and MLSS (2520–4310 mg/l). The analyzed models were shown to be quadratic and highly significant by the F-value and P-value. The regression coefficients (R2) for the quadratic models developed for removal efficiency, COD, and BOD5 are 0.9996, 0.9995 and 0.9996, respectively. According to CCD-RSM, the optimal matching input factors for the greatest removal efficiency of BOD and COD were: MLLS = 3415 mg/l, time = 21 h and pH = 5.35. Using the traditional method, the maximum removal (95%) of BOD and COD was seen at pH = 6.5, time = 12 h and MLLS = 4310 mg/l.