earticle

영어

Carbon dioxide is one of the global warming gases. A utilization of a sustainable energy is one of the effective technologies for a mitigation of the CO2 accumulation in the atmosphere. If renewable energy can be used for methane synthesis, H2 is converted to methane with reducing CO2. We investigated the conversion of CO2 to CH4 using a novel hollow-fiber membrane
biofilm reactor. We have converted CO2 to CH4 with autotrophic methanogens using CO2 and H2. All gases diffused into water through the membrane without bubbles. We have successfully operated the Hf-MBfR for stable methane production from CO2 and H2 under continuous operations for 60 - 70 days at acidic and neutral pH. Methane ratio of produced gas depended on the pH condition and reached about 60% at neutral pH and 80～90% at acidic pH. At
neutral pH, during the operating periods, acetic acid was continuously produced to 4,000 ～ 7,000 ppm so that produced methane was considered to produce by hydrogenotrophic methanogens and acetoclastic methanogens. At acidic pH, during the initial operating periods, pH was maintained to 5.9～6.6 so that acetic acid was produced by acetogens. But after adjusting to less than pH 5.5 it was decreased, at the same time produced methane contents was increased by
acetoclastic methanogens. The produced methane contents were 751 ml/day on average from 20 days to 58 days at netral pH and 135 ml/day on average from 36 days to 43 days, 247 ml/day on average from 44 days to 70 days at acidic pH