Integrated A/O-MBR–NF process for treating high COD content wastewater from traditional Chinese medicine

Abstract

Traditional Chinese medicine (TCM) wastewater poses a significant environmental challenge due to its high chemical oxygen demand (COD) and complex components. This study demonstrates a highly effective treatment approach for complex TCM wastewater using a combination of hydrolysis-acidification (HA) pre-treatment, anaerobic-aerobic membrane bioreactor (A/O-MBR), and nanofiltration (NF). Pudilan Xiaoyan Oral Liquid (PDL) wastewater, characterized by high COD (around 5500 mg/L) and baicalin content, served as the model feedstock. The A/O-MBR demonstrated removal rates of 23.6 mg COD g biomass−1 h−1 and 1.0 mg NH3-N g biomass−1 h−1. The combined A/O-MBR-NF process achieved exceptional COD removal exceeding 99 %, significantly reducing the wastewater's environmental impact. Importantly, the treated effluent exhibited no biological toxicity in zebrafish acute toxicity tests, demonstrating the effectiveness of this approach in detoxifying PDL wastewater. Analysis of the A/O-MBR's bacterial community further elucidates the treatment mechanism. This study indicates that MBR treatment for complex TCM wastewater is feasible and holds promising industrial prospects, offering a fresh perspective on the treatment of TCM wastewater with high COD levels.