Electricity generation from mixed volatile fatty acids using microbial fuel cells.
Fermentative hydrogen production, as a process for clean energy recovery from organic wastewater, is limited by its low hydrogen yield due to incomplete conversion of substrates, with most of the fermentation products being volatile fatty acids (VFAs). Thus, further recovery of the energy from VFAs is expected. In this work, microbial fuel cell (MFC) was applied to recover energy in the form of electricity from mixed VFAs of acetate, propionate, and butyrate. Response surface methodology was adopted to investigate the relative contribution and possible interactions of the three components of VFAs. A stable electricity generation was demonstrated in MFCs after the enrichment of electrochemically active bacteria. Analysis showed that power density was more sensitive to the composition of mixed VFAs than coulombic efficiency. The electricity generation could mainly be attributed to the portion of acetate and propionate. However, the two components showed an antagonistic effect when propionate exceeded 19%, causing a decrease in coulombic efficiency. Butyrate was found to exert a negative impact on both power density and coulombic efficiency. Denaturing gradient gel electrophoresis profiles revealed the enrichment of electrochemically active bacteria from the inoculum sludge. Proteobacteria (Beta-, Delta-) and Bacteroidetes were predominant in all VFA-fed MFCs. Shifts in bacterial community structures were observed when different compositions of VFA mixtures were used as the electron donor. The overall electron recovery efficiency may be increased from 15.7% to 27.4% if fermentative hydrogen production and MFC processes are integrated.
Teng
Shao-Xiang
SX
Department of Chemistry, University of Science and Technology of China, Hefei, China.
Tong
Zhong-Hua
ZH
Li
Wen-Wei
WW
Wang
Shu-Guang
SG
Sheng
Guo-Ping
GP
Shi
Xian-Yang
XY
Liu
Xian-Wei
XW
Yu
Han-Qing
HQ
D001419:Bacteria / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001674:Bioelectric Energy Sources / Q000382:microbiology*; D004560:Electricity; D005232:Fatty Acids, Volatile / Q000378:metabolism*
D005232:Fatty Acids, Volatile