Sludge-based biochar-assisted thermophilic anaerobic digestion of waste-activated sludge in microbial electrolysis cell for methane production.

Affiliation

School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China. Electronic address: [Email]

Abstract

The development of microbial electrolysis cells (MECs) for methane production from waste activated sludge (WAS) is arrested due to the limited methane yield and fragile system stability. This study proposed a strategy to accelerate and stabilize MEC via 1.0 g/g DM (dry matter) sludge-based biochar (BC). The results showed that BC clearly accelerated methane production by 24.7% and enhanced VS removal efficiency by 17.9%, compared to control group. Variations of SCOD, proteins, carbohydrates and VFAs indicated biochar promoted hydrolysis and acidogenesis process. Cyclic voltammetry (CV) curves and coulombic efficiency (CE) suggested organic matters degradation and electron generation on anode were enhanced with supplement of biochar. Microbial community analyses revealed that biochar addition could both promote DIET through substituting exoelectrogen (e.g., Thermincola) on anode and enrich hydrogenotrophic methanogens (e.g., Methanothermobacter) on cathode, which is beneficial to development of MEC as to methane recovery from organic matters.

Keywords

Anaerobic digestion,Biochar,Electron transfer,Microbial electrolysis cells,Sludge,