報告書番号

V08041

タイトル（和文）

窒素除去能を有する水域直接浄化用ろ材の開発-硝化と脱窒を行う二重構造の袋状ろ材-

タイトル（英文）

Direct purification using filter material capable of nitrogen removal-dual bag capable of simultaneous nitrification and denitrification-

概要 （図表や脚注は「報告書全文」に掲載しております）

窒素除去能力を有する新しい接触ろ材を開発するため、アンモニア酸化菌Nitorosomonas europaeaと脱窒菌Paracoccus denitrificansを固定化した外袋と、99.5%エタノールを充填した内袋からなる袋状ろ材について検討した。袋状ろ材3個を入れた容器（200 mL容量）に、20 mg-N/L濃度のアンモニア溶液を50 mL/hで通水し、25℃の曝気条件下で106日間にわたって連続処理を行った結果、処理水中の総窒素濃度は4 mg-N/Lにまで低下し、流入アンモニアの80％が窒素ガスとして除去され、TOC濃度は5 mg-C/L以下で維持された。また、23 mLのエタノールを充填した内袋からのエタノール放出速度は0.021 mL・day-1であることから、袋状ろ材はエタノールを再充填することなく、長期間にわたって窒素除去能力を維持できると考えられる。

概要 （英文）

Biological treatment systems using nitrification-denitrification process have already applied to remove the nitrogen in various domestic and industrial effluents. The available systems, however, are not suitable for all polluted sources. They are unsuitable for small-scale and wide-ranging polluted streams and waterways, since they require many reactor tanks with complicated operations. In this study, we showed a dual bag system capable of nitrogen removal in a single step without additional operations. The dual bag was constructed with an outer non-woven fabric bag and an inner non-porous low-density polyethylene (LDPE) film bag. Nitrosomonas europaea cells and Paracoccus denitrificans cells were immobilized on the outer bag, and 23 mL of 99.5%(v/v) ethanol was packed into the inner hermetic bag. The dual bag removes ammonia as follow: Ammonia in the solution is oxidized to nitrite, and then the produced nitrite is reduced to nitrogen gas by the cooperation of N. europaea cells and P. denitrificans cells on the outer bag. Ethanol as an electron donor for denitrification is slowly supplied to the P. denitrificans cells from the inner hermetic bag. Ammonia solution (20 mg-N/L) flowed into a reactor tank (200 mL volume) with three dual bags (packed ratio 34.5%) was continuously treated with 2.6 h of hydraulic retention time at 25 C. Total nitrogen and total organic carbon concentration in the outflow of the reactor were kept below 4 mg-N/L and below 5 mg-C/L, respectively, for 106 days. The dual bags removed 80.0% of nitrogen from the solution without accumulating organic carbons. The inner hermetic bag containing 23 mL of ethanol releases ethanol probably for 1,000 days without refilling ethanol, since the inner bag released only 0.021 mL ethanol per day at 25 C. The dual bag system in this study would be effective to simplify the nitrogen removal system, since they are easily installed in vacant spaces of various waterways and tanks.

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