Electroactive bacteria–algae biofilm coupled with siphon aeration boosts high-salinity wastewater purification: A pilot study focusing on performance and microbial community

Constructed wetland–microbial fuel cells (CW–MFC) and aeration technology are typically used for the treatment of mariculture wastewater with a low carbon/nitrogen ratio and high-salinity. However, salt inhibition limits their efficiency. Here, based on CW–MFC, an electroactive bacteria–algae biofilm and siphon aeration technology were employed in a pilot study to validate their technical and economic feasibility. The system yielded average removal efficiencies of 80.99 % ± 1.3 %, 92.59 % ± 3.13 %, 94.03 % ± 5.11 %, 97.38 % ± 3.62 %, and 95.95 % ± 2.59 %, respectively, for chemical oxygen demand, total phosphorus, total nitrogen, sulfamethoxazole, and Cu2+, with an average voltage of 354 ± 23 mV. Nitrification and denitrification bacteria Vicingus (12.52 %), Marinobacter (7.93 %), Muricauda (10.86 %), and Xanthomarina (13.62 %); extracellular respiratory bacteria Geobacteraceae (9.47 %) and Pseudomonas (2.54 %); and microalgae bacteria Pseudooceanicola (12.45 %) and Hoeflea (7.45 %) were significantly enriched. The energy consumption per ton of sewage treatment was 0.0045 kWh·m−3, representing 47.87 % lower costs than those related to traditional aeration. These results proved the feasibility of CW–MFC coupled with electroactive bacteria–algae biofilm and siphon aeration tidal flow technology for mariculture wastewater treatment.