Selection of bacterial community on electrode by electric current for use as microbial fuel cell anode

Abstract

This dissertation studied the effect of anode electric current stimulation on open circuit voltage (Voc), current density and power density of MFC. Parameters which were used for electric current stimulation were stimulation periods, enrichment medium, carbon source in MFC, type and magnitude of electric current, and source of sediment. In addition, effect of nutrient broth (NB) and phosphate buffer basal medium (PBBM) on biofilm formation of stimulated anode were examined. Biofilm formation on anode was investigated under field emission scanning electron microscope (FESEM). It was found that thick biofilm was observed on AC stimulated anode at 10-15 mA. In addition, the different medium used in the enrichment of biofilm during AC stimulation led to the different characteristics of biofilm. Bacterial community on stimulated anode was isolated from biofilm anode. Electrochemical active bacteria (EAB) such as Shewanella putrefaciens, which effectively transferred electron to anode was isolated. The effect of AC stimulation on pure isolate showed that S. putrefaciens viable cell count was dramatically decreased (4 logCFU) when stimulated with 15 mA AC stimulation. In this dissertation, the highest Voc of 989 mV, produced from propionate-fed MFC with 60 days unstimulated anode in PBBM medium. However, the highest current density of 72.9 mA and power density of 13.4 mW m⁻², produced from acetate-fed MFC with 60 days, 5-10 mA AC stimulated anode in PBBM medium. Moreover, AC stimulation on anode can be used to stimulate different sources of sediments. Furthermore, application of stimulated anode for COD removal and electricity production was also investigated. It was found that the highest COD removal of 60% and 48 mA m⁻² current density was obtained from molasses-fed MFC by using 10 mA AC stimulated anode. Thus, it could be concluded that electric current stimulation is a high potential tool for selecting effective bacterial community on electrode and using as anode for the MFC.

Key findings

• ▸Electric current stimulation at 10-15 mA led to thick biofilm formation on the anode.
• ▸Different enrichment media used during AC stimulation resulted in varying biofilm characteristics.
• ▸Shewanella putrefaciens was isolated as an electrochemically active bacterium that effectively transferred electrons to the anode.

Keywords

Identifiers

DOI

10.58837/chula.the.2015.911

Journal

Unknown journal

Year

2015