成果報告書詳細
管理番号20120000000243
タイトル平成23年度中間年報 省水型・環境調和型水循環プロジェクト 水循環要素技術研究開発 高効率難分解性物質分解技術の開発うち新機能生物利用技術 (H21-H25)
公開日2012/6/9
報告書年度2011 - 2011
委託先名株式会社日立プラントテクノロジー
プロジェクト番号P09011
部署名環境部
和文要約1.研究開発の内容および成果
課題(a)「新機能微生物(アナモックス菌)の培養・維持」
(a)-1 中温型アナモックス菌の培養・維持
嫌気性アンモニア酸化細菌(アナモックス菌)による廃水処理システムを構築するためには,基本となるアナモックス菌を培養・維持する必要がある。さらに実用化に向けた検討を行う上では、大量のアナモックス菌の培養が必須の課題となる。そこで、培養槽容積2.5m3 のアナモックス菌超大型培養装置を製作し運転を開始した。今後、アナモックス菌の大量培養試験を行い、培養性能を検証する予定。
(a)-2 低温型アナモックス菌の集積培養
アナモックス菌を用いた廃水処理システムを,低水温条件に適用させる方法として,低水温下で高い活性を有する新しい“低温型アナモックス菌”の集積培養を実施中である。
昨年度までに、河川や湖沼から低水温条件下で集積培養することで、新種のアナモックス菌の培養に成功している。今回、さらに集積培養を進め、低水温アナモックス菌の温度特性について評価した。その結果、従来の中温型アナモックス菌の至適温度が37℃であったのに対し、低水温型それよりも低い温度に至適温度があることが明らかと成った。また、水温20℃の条件では、中温型アナモックス菌よりも高い活性を有することを確認した。今後、さらに培養を継続する予定である。
英文要約In the present study, novel nitrogen removal system using anammox (anaerobicammonium oxidation) bacteria has been developing for treatment of nitrogen industrial effluents, which are important processes in the water cycle. Conventionally, ammonia is treated biologically by nitrification/denitrification system. However, the denitrification process must be supplied with an additional organic carbon source, entailing higher operating costs. In the mid-1990s, an alternative process of nitrogen removal was reported, the so-called anammox. Since ammonium was used as electron donor for denitrification, anammox reaction does not require any addition of a electron donor such as methanol. Thus, the anammox process can reduce energy for aeration by half and remarkably reduce the amount of methanol used for the denitrification.
Our final goal is to develop the nitrogen removal process using anammox bacteria which can operate under low temperature. To this end, there are 6 themes in this program. (1) Cultivation; It has been reported that cultivation of anammox bacteria itself is quite difficult. We succeeded in the cultivation of novel anammox bacteria using continuous feeding reactor under low temperature. Moreover, it was cleared that its optimum temperature was around 20 °C. Also, we had constructed a large scale cultivation test reactor to attain anammox biomass for seed sludge of full-scale plant. (2) Immobilization; Biomass retention is most important technical issues to develop the anammox reactor since its biomass yield is extremely low. So, we applied gel entrapment technique to immobilize anammox bacteria. (3) Pretreatment system; Pretreatment process of nitritation process is required for anammox process because nitrite is required for denitrification in the anammox reaction. In continuous feeding test, stable nitritation performance was confirmed more than a half year. (4) Denitrification;
High nitrogen removal performance of 2.2 kg-N/m3/d on average was observed at 20 °C. (5) Aerobic denitrification; Development of novel aerobic denitrification systems using simultaneous nitritation and anammox in single reactors has been investigating. Two types of reactor were applied for the reactors. One system is that gel cubes which are both immobilized nitrifying bacteria and anammox bacteria, respectively, were used. Another one is SNAP process using fixed bed for anammox and nitrifying biofilms. In the bench-scale test, stable denitrification performance of 0.6 kg-N/m3/d was confirmed at moderately low temperature. Moreover, high nitrogen removal performance of 1.3 kg-N/m3/d was observed on the SNAP reactor (30 °C). (6) Microbiological analyses; We characterized microbial ecosystems of anammox and nitrifying PEG carriers in the startup period of the bench-scale reactor. First of all, we determined the spatial distribution of ammonia-oxidizing bacteria (AOB) and anammox bacteria by FISH analysis using anammox bacteria or ammonium oxidizing bacteria specific 16S rRNA targeted oligonucleotide probes. The results of FISH analysis showed that AOB were detected on the surface of the anammox carriers after 17 days of the operation of the bench-scale reactor. Also, we validated the growth of AOB in the anammox carriers by qauantitative PCR targeted to amoA gene. This implies that by modifying the microbial ecosystem, the anammox bacteria, which were first incubated in anoxic conditions, promptly adapted to the aerobic environment. However, no remarkable change was observed in the microbial ecosystem of nitrifying carriers. Moreover, we developed a monitoring tool for typing anammox bacaterial population. T-RFLP analysis (Primers AMX368F and 6-FAM labeled AMX820R; Hae III digest) revealed that Candidatus Kuenenia stuttgartiensis was the dominant bacteria in the anammox gel carriers.
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