成果報告書詳細
管理番号20100000001986
タイトル*平成21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/嫌気性アンモニア酸化プロセスを軸とした高効率窒素除去システムの開発」
公開日2010/11/10
報告書年度2009 - 2009
委託先名国立大学法人北海道大学大学院工学研究科
プロジェクト番号P07024
部署名バイオテクノロジー・医療技術開発部
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 本研究では、高濃度アンモニア性窒素含有廃水(例えば、メタン発酵消化液など)を高効率、低コスト、省エネルギーで処理することが可能である部分硝化-嫌気性アンモニア酸化(ANAMMOX)プロセスを開発する。バイオデザイン化技術の1つとして、アンモニア性窒素の亜硝酸までの部分硝化およびANAMMOX細菌の増殖促進を図るために微量のヒドロキシルアミン(NH2OH)を添加する。NH2OH添加法の部分硝化およびANAMMOX反応に及ぼす有効性は、各種分子生物学的手法および各種マイクロセンサーを用いてバイオフィルム内in situの微生物群集構造と機能を随時解析することで評価する(バイオモニタリング技術)。このプロセスの開発導入により、高効率・省エネルギー、低コスト型の窒素除去システムを構築する。
英文要約Title: Development of a high-performance nitrogen removal process based on anaerobic ammonium oxidation (ANAMMOX) for treatment of wastewaters generated from methanogenic treatment processes (FY2007-FY2011) FY2009 Annual Report
Anaerobic ammonium oxidation (ANAMMOX) is a microbiological oxidation of ammonium with nitrite as the electron acceptor and produces dinitrogen gas as the main product. The ANAMMOX process is a new and promising alternative to conventional nitrogen removal processes. Since ANAMMOX bacteria require nitrite as the electron acceptor, ammonium in wastewater has to be oxidized to nitrite in a preceding reactor. However, nitrite can be easily oxidized to nitrate in an oxic reactor. Therefore, inhibition of nitrite oxidation process (i.e., partial nitrification process) is needed. In this study, we tried to suppress nitrite oxidation process with hydroxylamine. In this study, we investigate the effect of hydroxylamine on the partial nitrification and ANAMMOX processes by molecular biological techniques and microsensor analysis.
The partial nitrification reactor was made up of cylindrical glass. The reactor has an inner diameter of 45 mm and height of 500 mm. The liquid volume was 0.8 L. The reactor consisted of several vertically suspended polyester porous nonwoven strips (210 by 20 by 8 mm). Pre-incubated sludge for 20 d was inoculated into the reactor. An artificial medium was fed to the reactor in up-flow mode using a peristaltic pump. The concentrations of ammonium in the medium were gradually increased. Nitrite oxidation was completely inhibited in the nitrification reactor (partial nitrification reactor) by dosing hydroxylamine with nitrite production rate of 1.1 kg-N/m3/day.
An anaerobic up-flow granular bed ANAMMOX reactor was developed. ANAMMOX bacterial granules were cultivated with a synthetic nutrient medium in an anaerobic up-flow reactor. A net working volume of the reactor was 0.15 L (28 cm in length, 2.6 cm in diameter). The reactor was inoculated with ANAMMOX biomass originated from an up-flow fixed bed ANAMMOX biofilm reactor. After the appropriate sludge volume was obtained, the ANAMMOX reactor was connected to the partial nitrification reactor. During the initial phase, the nitrogen loading to the ANAMMOX reactor had never exceeded 10 kg-N/m3/day, so that the hydrogen retention time of the partial nitrification reactor were gradually decreased. After reduction of hydrogen retention time down to 0.4 h, The removal rate of total inorganic nitrogen, defined as the sum of NH4+, NO2– and NO3– concentrations (represented by T- Ni), of the up-flow granular bed ANAMMOX reactor reached over 15 kg-N m-3 day-1, which might be the highest nitrogen removal rate among the partial nitrification- ANAMMOX reactors reported previously. Such a high rate is due to removal of oxygen from the influent of the ANAMMOX reactor and enrichment of ANAMMOX biomass.
N2O production rates in the partial nitrification and ANAMMOX reactors were monitored. The N2O production rate in the partial nitrification reactor accounted for 3.8±0.5 % of nitrogen conversion rate. The N2O production rate in the ANAMMOX reactor accounted for 0.14±0.5 % of nitrogen conversion rate. This indicates that the N2O production rate in the partial nitrification reactor was 50 times higher than that in the ANAMMOX reactor.
The effect of nitrogen loading rate and DO concentrations on the partial nitrification process were investigated. Under low nitrogen loading rate (<0.5 kg-N m-3 day-1) the complete nitrification was observed. With increasing the nitrogen loading rate, the nitrite production rate was gradually increasing. After the nitrogen loading rate was over 1.0 kg-N m-3 day-1, the partial nitrification process was accomplished. This indicates that partial nitrification is stable when the nitrogen removal rate is controlled at high rate (>1.0 kg-N m-3 day-1).
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