Deciphering the roles of suspended sludge and fixed sludge at electrode in microbial fuel cell accomplishing sulfide-based autotrophic denitrification

• Published in: Biochemical engineering journal 2023-04, Vol.193, p.108874, Article 108874
• Main Authors: Cai, Jing, Qaisar, Mahmood, Chen, Bilong, Wang, Kaiquan, Wang, Ruyi, Lou, Juqing
• Format: Article
• Language: English
• Subjects: Fixed sludge at electrode; Microbial community; Microbial fuel cell; Sulfide-based autotrophic denitrification process; Suspended sludge
• ISSN: 1369-703X; 1873-295X
• DOI: 10.1016/j.bej.2023.108874

The roles of suspended sludge and fixed sludge at electrode in combined with sulfide-based autotrophic denitrification by progressively decreasing suspended sludge at a fixed nitrate concentration (50 mg/L) in microbial fuel cell (MFC) was investigated. The suspended sludge is involved in nitrate reduction and sulfate conversion; however, the contributions of fixed sludge at electrode are greater than those of suspended sludge in substrate transformations. The electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) analyses suggested that suspended sludge helped to improve the electron transport capacity and reduced the internal resistance. The best performance in terms of electricity generation was demonstrated with fixed sludge at electrode only. The dominant microbial genera in fixed sludge at electrode include Acidithiobacillus, Sulfurimonas, Sulfurovum and Halothiobacillus, while latter three genera are dominant in suspended sludge, with relative high abundance of denitrifying species (Thauera and Rhodobacteraceae). [Display omitted] •Suspended sludge was conducive to nitrate reduction and sulfate conversion.•Contribution of fixed sludge at electrode in substrate conversion was great.•Suspended sludge improved electron transport and reduce internal resistance.•MFC with fixed sludge at electrode only showed best electricity generation.•Acidithiobacillus was the endemic dominant genus in fixed sludge at electrode.