Discerning the effect of operating conditions on the improvement of up-flow constructed wetland-microbial fuel cell performance in treating mixed azo dyes wastewater and bioelectricity generation

• Published in: Energy, ecology and environment (Online) Vol. 9; no. 3; pp. 301 - 313
• Main Authors: Teoh, Tean-Peng, Ong, Soon-An, Ho, Li-Ngee, Wong, Yee-Shian, Lutpi, Nabilah Aminah, Tan, Sing-Mei, Ong, Yong-Por, Yap, Kea-Lee
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.06.2024; Springer Nature B.V
• Subjects: Aquatic plants; Artificial wetlands; Azo dyes; Biochemical fuel cells; Biodegradation; Bioelectricity; Circuits; Color removal; Decoloring; Decolorization; Dyes; Earth and Environmental Science; Ecology; Efficiency; Electric power generation; Electrodes; Electrons; Energy; Environment; Fuel cells; Fuel technology; Hydraulic retention time; Load distribution; Loading rate; Microorganisms; Mineralization; Organic loading; Original Article; Pollutants; Retention time; Substrates; Wastewater; Wetlands; Organic loading rate; Hydraulic retention time; Constructed wetland-microbial fuel cell; External resistance; Mixed azo dyes; Multiple circuit connections
• ISSN: 2363-7692; 2363-8338
• DOI: 10.1007/s40974-023-00314-4

This study assessed the effect of implementing multiple circuit connections and operating parameters (hydraulic retention time (HRT), organic loading rate (OLR), and external resistance) on the improvement of up-flow constructed wetland-microbial fuel cell (UFCW-MFC) in treating the mixed azo dyes wastewater and bioelectricity generation. The multiple-circuits UFCW-MFC facilitated the organic substrate degradation, which improved the removal efficiency of dyes by 8% and COD by 7%, as well as power production by 6.5 times, compared to single-circuit UFCW-MFC. The prolonged HRT from 1 to 3 d extended the interaction time between the pollutants and microbes, which further enhanced the removal efficiency of dyes by 9% and COD by 6%. The decrease in power generation by 1.3 times could be ascribed to the lower OLR at a higher HRT (0.864–0.288 g COD/d when HRT extended from 1 to 3 d) as the utilization of electrons was prioritized for decolorization compared to bioelectricity generation. The increase in OLR (0.288 to 0.754 g COD/d) with the same HRT (3 d) exhibited an improvement of 4% in decolorization and 2.4 times in power generation. This could be attributed to more electron production from the higher COD removal. The lower external resistance benefited the UFCW-MFC performance, where the best performance was obtained at 200 Ω as it approached the internal resistance (150 Ω).