17:15 〜 18:45
[AHW22-P12] Coupling Effects of Biochar and Sediment Microbial Fuel Cells on CH4 and CO2 Emissions from Rice Straw-Treated Paddy Soil
キーワード：biochar incorporation , methane, Reduction, power generation, SMFCs, paddy soil
Sediment microbial fuel cells (SMFCs) contribute to mitigating methane (CH4) emissions from the soil through weakening methanogenesis by competing with electroactive microorganisms. Integrated approaches can be more effective in increasing the efficiency of SMFCs with reducing CH4 emissions. The purpose of this study was therefore to investigate the effect of coupling SMFC with biochar as a potential method on reduction of CH4 emission from straw-amended paddy soil. Simultaneously, the performance of electricity production was evaluated. Lab-scale microcosms were set up using acrylic cylindrical columns (25 cm height and 9 cm inner diameter). Biochar was prepared from rice straw by pyrolyzing at 800oC for 1 h in the atmospheric N2. The experiment consisted of six SMFC treatments amended with 0%, 1%, and 2% biochar derived from rice straw under SMFC (closed circuit) and without SMFC (open circuit) conditions in triplicate. Rectangular steel mesh electrodes (15 x 3 cm) and carbon felt (6 x 5 cm) were used as anode and cathode materials, respectively. Each column was filled with 200 g of paddy soil (< 2 mm) and 1.5 L of deionized water. The experiment was run for 60 days at 25oC. Results showed that cumulative CH4 emission in the SMFC treatment was significantly smaller (P < 0.001) by 38% than the control (no biochar, no SMFC) treatment. Cumulative CH4 emissions were further reduced by 56% and 60% in 1% and 2% biochar-incorporated SMFC treatments, respectively, compared with the control treatment (no biochar, no SMFC). Biochar addition reduced CH4 emission from straw-treated paddy soil, but no significant differences between SMFCs and no SMFC treatments (P > 0.05). This suggests that the application of biochar probably enhanced the growth of methanotrophs that would work as extracellular transfer of electrons to alternative acceptors in the sediment. However, the effects of SMFC and biochar were insignificant in CO2 emission (P > 0.05). Moreover, biochar incorporation did not enhance the current generation in SMFCs, which resulted in insignificant differences in CH4 emission between SMFCs and no SMFC treatments (P > 0.05). In conclusion, biochar stimulated methanotrophic activities and the efficiency of SMFC, resulting in higher sediment redox conditions and the interactive effects of biochar and SMFC probably led to less CH4 emissions from straw-treated paddy soil.