Deciphering physicochemical properties and enhanced microbial electron transfer capacity by magnetic biochar

Magnetic biochar is important for improving the electron transfer capacity (ETC) of microorganisms in waste-water treatment. In this study, three magnetic biochar under different pyrolysis temperatures (300, 500 and 700 ?) were prepared by co-precipitation, and their characteristics and impacts on mediating microbial ETC were investigated. Results indicated that magnetic biochar had a higher capacitance and conductivity than pyrolytic biochar, with the largest specific capacitance of 14.7F/g for FCS700 (magnetic biochar prepared at 700 ?). The addition of magnetic biochar could improve the nitrogen removal efficiency of a sludge-biochar system. The electron transfer resistance (Rct) of magnetic biochar was lower than pyrolytic biochar by 25.5 % (300 ?), 19.7 % (500 ?), and 11.6 % (700 ?), respectively. The structure of the microbial community in the sludge-biochar system differed significantly. Spearman correlation suggested that the electrochemical properties of biochar were an important factor affecting the structure of the microbial community.

Automated summary

Magnetic biochar is found to be important for improving the electron transfer capacity of microorganisms and can enhance the nitrogen removal efficiency in waste-water treatment systems. Magnetic biochar has higher capacitance and conductivity compared to pyrolytic biochar, and it significantly influences the structure of microbial communities.