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

Abstract

A novel anaerobic ultrafiltration membrane bio-fuel cell (UFBFC) was concep- tualized to improve the efficiency of wastewater treatment with a reduced foot- print 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 treat- ment 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 oper- ated with external resistance of 100 Ω (24 Wh/m3). The harvested energy by UFBFC with capacitor-based power management system thus could success- fully compensate the operational power requirement of the system, proving its practical field-scale applications as an energy-economic advanced wastewater treatment system.