Nitrogen Removal Efficiency and Microbial Metabolic Analysis in an Iron-Carbon Based Constructed Wetland-Microbial Fuel Cell for Mariculture Wastewater Treatment

Abstract

Constructed wetlands (CWs) for treating mariculture wastewater have received widespread attention,This study constructed a CW-MFC system using iron-carbon (Fe-C) as an anode filler to investigate its performance in purifying mariculture wastewater, electricity generation, and microbial community dynamics. After nearly 30 days of operation, the CW-MFC showed excellent performance in removing target pollutants and generating electricity, with a COD removal rate of 95.84 ± 0.58%, NH4+-N removal rate of 84.22 ± 2.68%, and NO3--N removal rate of 98.17 ± 0.28%. During the stable period, the average output voltage was 713.59 mV, with a power density of 111.27 mW/m². Functional genera Halomonas and Alkalibacter greatly enriched at the anode, significantly enhancing denitrification and nitrogen removal capabilities in the system. Metagenomic analysis showed that the abundance of denitrifying enzyme genes in the anode of CW-MFC compared to the CW, and carbon and nitrogen-related metabolism significantly increased.

Keywords: Constructed wetland, Microbial fuel cell, Fe-C, Electricity production performance, Microbial community, Mariculture wastewater.