Comparing of effect of various conductive materials and substrates on enhancement of methane production

Author(s): Stella Chan
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Institution or organization of origin: Soka University
Country: Japan


Anaerobic digestion (AD) is a microbial process that produces renewable energy in the form of methane gas by treating various organic waste. Recently, it has been reported that addition of conductive materials (CMs) can help improve methanogenesis by promoting direct interspecies electron transfer (DIET) between exoelectrogenic bacteria and electron-accepting methanogens, but only with the presence of exoelectrogenic bacteria, i.e. Geobacter sp. Recently, it has been reported that when ethanol was used as substrate, the increase of Geobacter sp. was observed. Therefore, using ethanol as substrate may be an important factor in cultivation for DIET to occur efficiently. Besides, the effect of DIET is considered to be dependent on the type of CMs including their physicochemical properties, yet research for direct comparison on the effect of different CMs on DIET under the same experimental condition is still limited. In this study, granular activated carbon (GAC), multi-walled carbon nanotube (MWCNT) and polyaniline (PANI) were used and evaluated their methanogenesis efficiencies in two sets of experiments. For comparison of substrate, sodium propionate was used in the experiment 1 as control, while ethanol was used in the experiment 2. Results shows significant enhancement of methanogenesis in all the CMs conditions only in experiment 2, and the order was followed by GAC>MWCNT>PANI>non-CM addition condition (Control). Result also shows the value of BET specific surface areas of CMs are in the same order. Furthermore, the of Geobacteraceae, which is known to contribute to the DIET, was observed at the end in experiment 2 only.

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