Development and mechanistic insights of a photocatalytic-algae-bacteria degradation coupling system for treating toxic coking wastewater

Coking wastewater, characterized by high biological toxicity, poses significant challenges for traditional biological treatment methods. This study developed a novel in-situ immobilized photocatalytic-algae-bacteria consortia (P-ABC) system using a polyether polyurethane sponge as a carrier, aiming to enhance biological treatment efficiency for actual coking wastewater. Results showed a 16.8 % increase in algal density (up to 1.51 × 10⁵ cells/mL) in the P-ABC system compared to non-coupled controls, with significantly improved microbial metabolic activity, confirming the carrier's exceptional biocompatibility. Compared to standalone algae-bacteria consortia systems, the P-ABC system achieved higher removal efficiencies for chemical oxygen demand (COD Cr , 19.8 %), total organic carbon (TOC, 21.2 %), and total nitrogen (TN, 30.4 %). These findings validate the system's potential for improving stable and efficient treatment of industrial wastewater. Furthermore, this study offers insights into bio-enhanced treatment technologies and provides a reference pathway for integrating advanced oxidation and biological processes.