Phenol-driven ammonium recovery from coal chemical wastewater in a bioelectrochemical system (BES)

Bioelectrochemical systems (BES) have gained considerable attention in the past decade as a potentially sustainable and cost-effective method for coal chemical wastewater (CCW) treatment. However, a scarcity of studies focusing on the recovery NH₄⁺-N in the recycling treatment of CCW via BES technology. In this study, a BES-ammonium recovery system (BES-ARS) was proposed to remove phenol and NH₄⁺-N simultaneously, while NH₄⁺-N was further recovered in a downstream recovery unit. Through systematic evaluation, we identified optimal condition for both phenol and NH₄⁺-N removal. Specifically, an influent phenol-to-ammonium ratio of 2.0 was found to be ideal for maximizing simultaneous removal efficiency. Additionally, an evaluation of the nitrogen distribution showed that 97.9 % of NH₄⁺-N migrated to the cathode chamber, with 82.5 % of NH₄⁺-N being recovered in the absorbent under optimal condition. Furthermore, the solution not only reduces operational costs by up to 68 % compared to conventional treatments, but also conserves energy. This study presents an efficient and environmentally friendly treatment method for treating CCW, while recovering NH₄⁺-N as a valuable resource.