Electro-mediated biological system coupled with arrayed tubular electrode module for enhancing pharmaceutical...

The poor biodegradability of industrial wastewater hinders the conversion of refractory organonitrogen into ammonia nitrogen in anaerobic biological treatment. This limitation consequently obstructs the subsequent carbon-nitrogen conversion process, highlighting the urgent need for effective treatment strategies. In this study, we developed a novel electro-mediated biological system (EMBS) coupled with an arrayed tubular electrode module (ATEM) at pilot-scale for the first time, which utilizes electromotive force to stimulate microbial metabolism to treat pharmaceutical wastewater through carbon and refractory organonitrogen conversion. The application of an electrically-driven process in EMBS significantly reduces aromatic organics and transforms toxic heterocyclic compounds into less toxic small-molecule amines. This led to a 107.5 % increase in chemical oxygen demand (COD) removal efficiency and a 14.2 % higher organonitrogen conversion. The up-regulation of the tricarboxylic acid cycle and riboflavin metabolism resulted in the generation of NADH and flavin adenine dinucleotide, which promoted oxidative N-dealkylation of amine and sulfhydryl oxidation of heterocyclic compounds. Electro-stimulation up-regulated the expression of cytochrome c, thereby enhancing extracellular electron transfer, and increased the production of protein-rich extracellular polymeric substances, which supported microbial growth and adhesion. Finally, EMBS removed 44.04 % COD and 48.5 % organonitrogen while facilitating EMBS-A/O/A-membrane bioreactor pilot-scale process, ultimately reducing effluent COD and TN to 40.2 ± 22.3 mg/L and 52.3 ± 5.2 mg/L, respectively, demonstrating notable improvements in water quality and meet the discharge standard. The scalable ATEM provides a promising approach for full-scale EMBS applications that aims to optimize industrial wastewater treatment strategies, and address critical challenges in excessive carbon and nitrogen emissions.