Aerogel-based biofilm-membrane bioreactor and its preliminary economic assessment for efficient organic removal from...

Coalbed methane produced water (CBMPW) is characterized by high salinity and a complex mixture of organic contaminants, which severely inhibit microbial activity during treatment and consequently reduce treatment efficiency. To overcome this challenge, three aerogel-based biocarriers-chitosan aerogel (CSA), sodium alginate aerogel (SAA), and chitosan/sodium alginate composite aerogel (CS/SAA) were developed in this study. These aerogels were used as fillers in a biofilm-membrane bioreactor (BF-MBR) system. The results demonstrate that the novel CS/SAA composite aerogel possesses a high specific surface area (89.34 m² g^-1) and a stable three-dimensional mesoporous structure, which markedly enhances microbial attachment and mass transfer efficiency. In the CS/SAA-based BF-MBR system, visible biofilm coverage was observed on the CS/SAA surface within 15 days after sludge inoculation. Following 91 days of continuous operation, the system selectively enriched halotolerant microbial communities dominated by Marinimicrobium and Halomonas, achieving excellent organic matter removal performance, with average removal efficiencies of 75 % for dissolved organic carbon and 85 % for UV₂₅₄. In addition, the CS/SAA-based BF-MBR effectively mitigated membrane fouling, achieving a flux recovery rate of 88 % while reducing the irreversible fouling ratio to 12 %. Preliminary economic assessment under bench-scale conditions indicated that CS/SAA exhibited the most favorable relative cost-related metrics among the three carriers tested. This study highlights the potential of composite aerogels as high-performance microbial carriers and provides valuable guidance for material selection in future pilot-scale studies for hypersaline wastewater treatment.