成果報告書詳細
管理番号20110000000688
タイトル*平成22年度中間年報 微生物機能を活用した環境調和型製造基盤技術開発/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/高濃度微生物保持DHSリアクターによるリン回収技術の開発
公開日2011/6/7
報告書年度2010 - 2010
委託先名国立大学法人広島大学
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)研究開発の内容 従来の生物学的リン除去プロセスでは嫌気と好気条件を繰り返す事でポリリン酸蓄積細菌にリンを取り込ませ、その汚泥を回収する事によりリン除去が行われる。一方で、余剰汚泥の無い排水処理方法は非常に好ましいことであるが、余剰汚泥が発生しないシステムではリン除去は出来ない。また、リン除去プロセスを持たない処理施設も多くある。これらの処理水からリンを除去し回収する事は緊急の課題である。そこで、密閉型DHSリアクターによる汚泥回収に依らないリン回収システムが考案されている。
英文要約In this study, we have been developing an innovative phosphorous recovery process without excess sludge disposal using down-flow hanging sponge (DHS) reactor. In this financial year, we have studied the following things; investigations of improving phosphorus removal efficiency using a lab-scale closed DHS reactor, genomic analyses of a new polyphosphate-accumulating organism (PAO) and a new glycogen-accumulating organism (GAO), and a set-up of a pilot-scale plant for the investigation of phosphorus removal and recovery performance with feeding an actual municipal sewage.
A closed DHS reactor, having 2.5 L of column volume, was used for investigations of operation methods improving phosphorus removal efficiency. In this study, newly designed 24 cylindrical carriers covered with cloth on a string were installed and hung in the reactor in place of sponge carriers because the specific surface area is larger than that of conventional sponge and the immobilization of PAO is expected to increase for better phosphorus removal. The reactor was operated for 345 days under anoxic/aerobic conditions at a cycle of 4 h anoxic and 8h aerobic times at 20 degrees C. This cycle time was conducted as optimal operation, which was derived from the experimental data obtained last year. Under the aerobic condition, an inorganic artificial wastewater containing 5 mg P/L of phosphate was fed into the reactor at an HRT of 20 min. On the other hand, the reactor was filled with the other artificial wastewater containing acetate and propionate as organic carbon sources and kept for 4 h to make the anoxic condition. As a result, in the first phase, the phosphorus removal efficiency and the recovered phosphorus concentration achieved 50% and 120 mg P/L, respectively. In addition, based on the time course of performance in one cycle, we found the reason why the phosphorus removal efficiency was not so high. The causes are as follows: (I) a high concentrated phosphorus liquid retained in the carriers is washed out at the changeover to the aerobic period following the anoxic period, and (II) phosphorus uptake rate decreases in the latter term of aerobic period. In the second phase, a recirculation of effluent was employed without outflow in the first 1 hour of the aerobic period to solve the problem I. This operation was effective, and the phosphorus removal efficiency was improved from 50 to 60%. In order to overcome the problem II, changing phosphate loading rate was carried out in the aerobic period of the third phase. The influent flow had a graded decrease every hour. In this manner, the phosphorus removal efficiency is expected to achieve over 98% in theoretical calculation. Considering this information, we conclude that further improvement of the removal efficiency would be expected by using higher reactor to increase HRT and down-flow velocity.
In order to understand a competition between PAO and GAO for more stable and effective phosphorus removal efficiency, we tried to analyze genomic sequences of PAO and GAO by matagenomic approaches. First of all, a PAO was enriched in another closed DHS reactor solely with acetate. A GAO was also enriched by using a tubular-type biofilm reactor.
To intensively support the development of innovative phosphorous recovery process, we designed and constructed the pilot-scale DHS plant, which has a size of 70 L of column volume and 2 m of height. The pilot-scale plant has been installed in Higashi-hiroshima municipal sewage treatment center and will be operated from this coming April.
ダウンロード成果報告書データベース(ユーザ登録必須)から、ダウンロードしてください。

▲トップに戻る