A novel application of TPAD–MBR system to the pilot treatment of chemical synthesis-based pharmaceutical wastewater

A pilot-scale test was conducted with a two-phase anaerobic digestion (TPAD) system and a subsequential membrane bioreactor (MBR) treating chemical synthesis-based pharmaceutical wastewater. The TPAD system comprised a continuous stirred tank reactor (CSTR) and an upflow anaerobic sludge blanket-anaerobic filter (UASBAF), working as the acidogenic and methanogenic phases, respectively. The wastewater was high in COD, varying daily between 5789 and 58,792 mg L−1, with a wide range of pH from 4.3 to 7.2. The wastewater was pumped at a fixed flow rate of 1 m3 h−1 through the CSTR, the UASBAF and the MBR in series, resulting in respective HRTs of 12, 55 and 5 h. Almost all the COD was removed by the TPAD–MBR system, leaving a COD of around 40 mg L−1 in the MBR effluent. The pH of the MBR effluent was found in a narrow range of 6.8–7.6, indicating that the MBR effluent can be directly discharged into natural waters. A model, built on the back propagation neural network (BPNN) theory and linear regression techniques, was developed for the simulation of TPAD–MBR system performance in the biodegradation of chemical synthesis-based pharmaceutical wastewater. The model well fitted the laboratory data, and was able to simulate the removal of COD.