Bioelectrochemically-assisted vermibiofilter process enhancing stabilization of sewage sludge with synchronous electricity generation

Abstract

Bioelectrochemically-assisted vermifilter (VBFBE) with sewage sludge as the anode fuel was constructed to accelerate composting of sewage sludge, which could increase the quality of the compost and harvest electric energy in comparison with vermicomposting and electrochemical only. Results revealed that the sludge stabilization with a higher soluble chemical oxygen demand (SCOD) and lower NH4+-H during 40 days of composting. At the composting, pH, C/N, electrical conductivity (EC) and germination index (GI) results demonstrated that the maturity degree of VBFBE4 was higher than that of other VBFBE. The VBFBE4 yielded a voltage of 1.024 V and maximum power density of 105.28 mW/m2 on 3th day. The bacteria in VBFBE4 were richer and higher in terms of diversity than those in other VBFBE, that was demonstrated that combination vermicomposting and electrochemistry could improve the sludge stabilization degree, accelerate sludge composting process and enhance composting maturity.