Enrichment of electricigenic biofilm for synchronized generation of electric current and waste water treatment in microbial fuel cells

Abstract

Enrichment of electricigens was carried out in double chamber Microbial fuel cells (MFCs) for synchronized organic waste treatment and bioenergy recovery. Activated sludge was inoculated in MFCs to measure the effect of two carbon sources (sucrose and acetate) on current output. MFCs operated with sucrose showed current generation of 5μA and 3μA with COD removal efficiency (86.04% and 77.85%) in two respective stages of enrichment. Whereas, the relative efficiency of MFCs run with acetate remained considerably low in the 1st stage though it inclined to 4μA with 81.17% removal of COD after 2nd stage of enrichment. Culture based analysis of anodic biofilms indicated the presence of different bacterial species i.e. Pseudomonas sp., Proteus sp., Citrobacter sp., with different biofilm forming capabilities (strong 5%, moderate 15% and weak 14.8%) in sucrose and acetate fed MFCs. 454 pyrosequencing of acetate-fed MFC indicated clear difference between established biofilm communities on anode and sludge sample. Anodic biofilm was covered with both culturable and un-culturable Pseudomonas species along with Nitrosomonas europaea and Massilia sp., etc. Principle component analysis also confirmed that major contributing classes were a-proteobacteria (48.51%), β-proteobacteria (31.48%) and γ-proteobacteria (16.16%). The results of current study implied that enrichment technique resulted in better selection of electricigens along with waste water treatment.