Energy production and denitrogenation performance by sludge biochar based constructed wetlands-microbial fuel cells system: Overcoming carbon constraints in water

Boda Ouyang; Zhiyong Zhang; Fuzhi Chen; Fei Li; Ming-Lai Fu; Huachun Lan; Baoling Yuan

doi:10.1016/j.watres.2024.123024

Energy production and denitrogenation performance by sludge biochar based constructed wetlands-microbial fuel cells system: Overcoming carbon constraints in water

Water Res. 2024 Dec 21:273:123024. doi: 10.1016/j.watres.2024.123024. Online ahead of print.

Authors

Boda Ouyang¹, Zhiyong Zhang², Fuzhi Chen¹, Fei Li¹, Ming-Lai Fu³, Huachun Lan², Baoling Yuan⁴

Affiliations

¹ Xiamen Key Laboratory of Municipal and Industrial Solid Waste Utilization and Pollution Control, College of Civil Engineering, Huaqiao University, Xiamen, Fujian 361021, PR China.
² Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China.
³ Xiamen Key Laboratory of Municipal and Industrial Solid Waste Utilization and Pollution Control, College of Civil Engineering, Huaqiao University, Xiamen, Fujian 361021, PR China. Electronic address: mlfu@hqu.edu.cn.
⁴ Xiamen Key Laboratory of Municipal and Industrial Solid Waste Utilization and Pollution Control, College of Civil Engineering, Huaqiao University, Xiamen, Fujian 361021, PR China; Key Laboratory of Songliao Aquatic Environment, Ministry of Education, Jilin Jianzhu University, Changchun, 130118, PR China. Electronic address: yuanbl@hotmail.com.

PMID: 39733529
DOI: 10.1016/j.watres.2024.123024

Abstract

As freshwater demand grows globally, using reclaimed water in natural water bodies has become essential. Constructed wetlands (CWs) are widely used for advanced wastewater treatment due to their environmental benefits. However, low carbon/nitrogen (C/N) ratios in wastewater limit nitrogen removal, often leading to eutrophication. This study explores the use of sewage sludge biochar (SB) and activated carbon (AC) as electrodes in microbial fuel cell-constructed wetlands (MFC-CW) to enhance nitrogen removal and energy generation. Results indicated that the sludge biochar closed-circuit CW (MSBS-CW) achieved considerable total nitrogen removal (95.85 %) and maximum power density (9.05 mW/m²). Furthermore, high-throughput sequencing and functional gene analysis revealed substantial shifts in the microbial community within MSBS-CW, particularly in the electroactive bacteria (Geobacter), autotrophic denitrifying bacterium (Hydrogenophaga, Thiobacillus) and anaerobic ammonium oxidation bacteria (Candidatus_Brocadia). Electrochemical and material characterization showed that SB enhanced the cathode's electrochemical performance and the anode's biocompatibility, thereby improving denitrification and energy generation. This study demonstrates that sludge biochar is an effective low-cost electrode material for MFC-CW systems, offering a sustainable solution for nitrogen removal and energy production under carbon-constrained conditions.

Keywords: Carbon limitation; Constructed wetland; Denitrifying bacteria; Microbial fuel cell; Sewage sludge-biochar.