Aerobic Denitrification Is Enhanced Using Biocathode of SMFC in Low-Organic Matter Wastewater

Abstract

Nitrate (NO3−) in wastewater is a rising global threat to ecological and health safety. A sufficient carbon source, as the electron donor, is essential in the conventional biological denitrification process. It is not appropriate to add extra carbon sources into specific water bodies in terms of material cost and secondary pollution. Thus, innovative NO3− removal technologies that are independent of carbon sources, are urgently needed. This study constructed sediment microbial fuel cells (SMFCs) for aerobic denitrification in low-organic matter wastewater and explored the key factors affecting denitrification efficiencies. The SMFC treatments removed 72–91% NO3− through two main denitrifying stages which were driven by carbon sources (COD) and generated electrons, respectively. After COD was fully consumed, denitrification efficiencies were enhanced in SMFC treatments by 24–47% using the generated electrons within 3 days. In this stage, the NO3− removal efficiencies were positively correlated with external current intensities (p < 0.05). The improved denitrification efficiencies were attributed to two enriched phyla in the SMFC cathode. The dominant genera also demonstrated the heterotrophic denitrifying capacity of the SMFC biocathode. Furthermore, electrical characteristics could be used to monitor or regulate the denitrification process in the SMFC system. In conclusion, this study presents an innovative treatment strategy that is economical and eco-friendly compared with conventional physicochemical methods.

Use of Plackett–Burman and Box–Behnken Designs to Optimize Bioelectricity Production from Winery Residues

“…Furthermore, by incorporating theoretical frameworks and empirical findings, we advanced our understanding of complex interactions within the MFC system. The use of MFC for wastewater treatment is an area of great potential, which has demonstrated its ability to treat a wide range of contaminants, such as drugs [35], organic removal [36], dyes [37], or contribute to desalination [38] and bioelectricity generation [39][40][41]. These insights not only contribute to the development of sustainable energy technologies but also pave the way for further research on optimizing MFC operation, improving waste treatment processes, and exploring the potential synergies between waste valorization and renewable energy generation.…”

Challenges and applications of nitrate-reducing microbial biocathodes

“…graphite or carbon brushes [69,110,[164][165][166][167][168][169] and graphite granules [34,66,139,142,144,[170][171][172]67,90,108,109,121,125,126,136]. Composites materials were also used to increase the performance, for example carbon felt/multiwall carbon nanotube composite [123], coated carbon materials [140,141,173,174] or layered air-cathode [175].…”