Combination of sonophotolysis and aerobic activated sludge processes for treatment of synthetic pharmaceutical wastewater

The treatment ability and efficiency of sonophotolytic process, aerobic activated sludge (AS) process, and their combination in reduction of total organic carbon (TOC), total nitrogen (TN), chemical oxygen demand (COD), and biological oxygen demand (BOD) from a synthetic pharmaceutical wastewater (SPWW) were studied. Batch mode experiments were performed to obtain optimal experimental operating conditions for sonophotolysis process. Ultrasonic power of 140 W, initial pH solution of 2, and air flow rate of 3 L/min were found as optimum. The initial optimum molar ratio of H2O2/TOC was found to be 13.77 for sonophotolysis process alone in batch mode. In continuous mode, sonophotolysis was able to reduce TOC by 90% after 180 min retention time. Aerobic AS process alone after 48 h retention time reduced TOC by 67%. Combined sonophotolysis and aerobic AS processes improved the biodegradability of the SPWW and resulted in 98% TOC and 99% COD removal while decreasing the retention time in sonophotoreactor and aerobic AS reactor to 120 min and 24 h, respectively. Additionally, the consumption of H2O2 was reduced significantly in the combined processes.