Methane fermentation of alcohol stillage derived from fermented awamori mash : (II) Effect of the addition of calcium carbonate on gas production (Department of Bioscience and Biotechnology)

泡盛蒸留廃液のメタン発酵におけるガス発生量に及ぼす炭酸カルシウム添加の影響等を小型発酵により調べた。馴養スラッジヘ炭酸カルシウムを混合して発酵を行なうことにより高負荷条件下でも良好なガス発生量が得られた。ガス発生量は基質添加量の増加とともに増大したが,基質添加量が有機物量として0.9g以上の時には発酵液中に酢酸やプロピオン酸等の揮発性有機酸の蓄積が認められた。本発酵における最大基質負荷量は炭酸カルシウム無添加の発酵に比較して約3倍高い値であった。また,基質1g当たりのガス発生量は694mlであり,発生ガス中メタン含量は69%であった。発酵液のCOD値は発酵初期に急激に低下し,発酵8日間で8000ppmから30ppmに減少した。炭酸カルシウム添加スラッジを用いた連続メタン発酵における基質1g当たりのガス発生量は500mlであり,そのうち61%がメタンガスであった。Effect of calcium carbonate on methane production from alcohol stillage derived from fermented awamori mash was studied using 200ml syringe. Addition of calcium carbonate to the acclimated sludge containing a large quantity of substrate found to be effective for gas production in the mesophilic methane fermentation. The gas production increased with an increase in organic matter of stillage, however, the volatile fatty acids were significantly accumulated in the mash when the amount of loading was more than 0.9g of organic matter of stillage. The maximum loading of substrate on anaerobic fermentation in the presence of calcium carbonate was about 3 times higher than that of control. The whole gas production was 696ml per g of organic matter of stillage and methane ratio was 69%. The COD value of the mash rapidly decreased in the early stage of fermentation and achived from 8,000 to 30ppm in 8 days of incubation. Gas production in continuous methane fermentation was about 500ml per g of organic matter of stillage with a methane ratio of 61%