Effect of temperature on treating chemical synthesis-based pharmaceutical wastewater containing 7-ACA by a novel multi-stage loop membrane bioreactor

BACKGROUND: 7-amino cephalosporanic acid (7-ACA) is the most critical intermediate for cephalosporin antibiotics but has caused serious water pollution. In this study, a bench-scale test was conducted with a novel multi-stage loop membrane bioreactor (MsLMBR) to treat chemical synthesis-based pharmaceutical wastewater containing 7-ACA. RESULTS: The MsLMBR system comprised a multi-stage loop aerobic reactor and a separate membrane module operated at different temperatures. Results showed that for MsLMBR1 at 15°C, MsLMBR2 at 25°C and MsLMBR3 at 35°C, the average total chemical oxygen demands (TCODs) of the effluent were all less than 80 mg L^-1. For MsLMBR2 and MsLMBR3, the microorganisms had better microbial activities and drug-resistances, and the biological removal was given priority to TCOD removal. But for MsLMBR1, there was no significant difference between biological removal and physical removal at the early stage. Average 7-ACA concentration of effluent was less than 40 mg L^-1 at 35°C. The laboratory data fitted the simulated data well using a time series analysis model (TSAM) in a MsLMBR system. CONCLUSION: 7-ACA pharmaceutical wastewater was effectively treated in a MsLMBR system, which also performed well at low temperature. In addition, the TSAM was a valid means to simulate and predict the efficiency of removal of an organic substance.