成果報告書詳細
管理番号20110000000685
タイトル*平成22年度中間年報 微生物群のデザイン化による高効率型環境バイオ処理技術開発/デザイン化微生物群を用いた高効率固定床メタン発酵の研究開発
公開日2011/6/7
報告書年度2010 - 2010
委託先名財団法人電力中央研究所
プロジェクト番号P07024
部署名バイオテクノロジー・医療技術部
和文要約和文要約等以下本編抜粋:1. 研究開発の内容及び成果等 (1)通電型固定床メタン発酵槽のスケールアップ可能な形状の検討 これまで検討してきたデザイン化微生物群担体を電気制御する通電型固定床メタン発酵槽は、陽イオン交換膜を介してメタン発酵を行う発酵槽と対極槽が繋がったH型の構造をしている。このような構造では、対極槽のための設置面積やリアクター容積が大きくなるため、スケールアップの妨げとなる。そこで、スケールアップに適したリアクター形状を検討するために、まず対極を発酵液と隔てる陽イオン交換膜の必要性、すなわち2槽型である必要性を確認した。1つの槽の中に作用極(微生物群担体)、参照電極、対極のすべてを挿入した小スケールの通電型固定床メタン発酵槽を用い、通電なしの条件と設定電位を-0.6 V、-0.8 V(vs Ag/AgCl)とした条件で模擬生ごみのメタン発酵を行った。
英文要約Title : Development of High-efficiency Environmental Biotreatment Technology Using Artificially Designed Microbial Communities. Development of a methanogenic packed-bed reactor using designed supporting material with microbial consortium (FY2007-FY2011) FY2010 Annual Report
(1) Development of a scale-up bioelectrochemical methanogenic reactor : To simplify the bioelectrochemical methanogenic reactor (BEMR) model, we constructed a single-chamber BEMR (250 mL) without a proton-exchange membrane. However, the performance of this BEMR in degrading artificial garbage slurry was very low, and the effect of a cathodic electrochemical culture was absent. Therefore, we developed a scale-up BEMR (4.0 L) that had 2 chambers equipped with a proton-exchange membrane. The anodic chamber was placed in the center of the cathodic chamber (fermentation broth). (2) Performance of the scale-up BEMR in degrading artificial garbage : The scale-up BEMR was employed for degrading artificial garbage slurry (10% dog food) at -0.8 V (vs. Ag/AgCl), and the reactor performance was investigated. The stable methane production rate and chemical oxygen demand (COD) removal ratio were observed at a high organic loading rate (OLR) of 33.5 gCOD/L/day. Thus, we achieved the desired value of OLR (25.5 gCOD/L/day) by using our BEMR. (3) Structure of microbial consortium in the BEMR : The structure and succession of bacterial and archaeal consortium in the fermentation broth that grew under the electrochemical culture were analyzed by using terminal-restriction fragment length polymorphism (T-RFLP) with 16S rRNA genes. Bacterial T-RFLP showed terminal-restriction fragments (T-RFs) of 68, 91, 137, 148, and 258 bp as the dominant bacteria in the fermentation broth. On the other hand, T-RFs of 92, 186, 280, and 779 bp were detected as dominant archaea. These results indicate that the microbial community structure in the scale-up BEMR was similar to the structure of a small BEMR. Therefore, we believe that the similarity of the microbial consortium contributed to the stable operation of the scale-up BEMR at the high OLR. (4) Selection of a real organic waste : Three kinds of thickened sewage sludge (TSS) were selected for investigating the treatment efficiency of a methanogenic packed-bed reactor and BEMR, and the suspended solid and volatile suspended solid concentrations were determined. We chose the most concentrated TSS at a sludge treatment center in Yokohama. (5) Performance of a methanogenic reactor in degrading TSS : The operation with a TSS to construct seed sludge was started using a continuously stirred tank reactor, and the starting sludge was collected from a packed-bed methanogenic reactor that degraded artificial garbage slurry. The reactor performance was stable during the starting hydraulic retention time at 40 days (OLR: 1.3 gCOD/L/day). In future, we plan to operate the scale-up BEMR with a selected TSS.
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