Ultrafiltration membrane bio-fuel cell as an energy-efficient advanced wastewater treatment system

A novel anaerobic ultrafiltration membrane bio-fuel cell (UFBFC) was conceptualized to improve the efficiency of wastewater treatment with a reduced footprint and bioenergy recovery. The system with a working volume of 40 L reached a maximum power density of 23.3 mW/m² while treating synthetic wastewater with initial chemical oxygen demand (COD) of 2026 ± 61 mg/L and 19.1 mW/m² while treating actual fish processing wastewater with initial COD of 1915 ± 63 mg/L. The average COD removal efficiency of UFBFC was found to be almost similar (>97%) for both types of wastewaters showing the efficacy of the system in real-life applications comparable to the existing treatment systems. The cost-effective longitudinal vibrational mechanism (0.25 $/kLD of treated wastewater), with a frequency of 0.5 Hz and an amplitude of 8 mm, revealed superior anti-biofouling ability for ultrafiltration membrane placed inside the anodic chamber of UFBFC than cost-intensive conventional techniques (117 $/kLD in conventional MBR with aeration). The capacitor-based power management circuit improved the maximum normalized energy recovery (58 Wh/m³) of UFBFC by over twice compared to UFBFC when operated with external resistance of 100 Ω (24 Wh/m³). The harvested energy by UFBFC with capacitor-based power management system thus could successfully compensate the operational power requirement of the system, proving its practical field-scale applications as an energy-economic advanced wastewater treatment system. Highlights: Ultrafiltration membrane bio-fuel cell (UFBFC) for efficient wastewater treatment Cost-effective longitudinal vibration technique for reduced membrane biofouling Chemical oxygen demand removal efficiency of UFBFC was >97% Capacitor-based circuit improved normalized energy recovery of UFBFC UFBFC successfully used to treat synthetic as well as fish processing wastewater.