| Project/Area Number |
11660239
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Irrigation, drainage and rural engineering/Rural planning
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| Research Institution | GIFU UNIVERSITY |
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Principal Investigator |
NISHIMURA Naomasa GIFU UNIVERSITY, FACULTY OF AGRICULTURE, ASSOCIATE PROFESSOR, 農学部, 助教授 (80180644)
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| Co-Investigator(Kenkyū-buntansha) |
AMAYA Takao GIFU UNIVERSITY, FACULTY OF AGRICULTURE, PROFESSOR, 農学部, 教授 (80033265)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2000: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1999: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | Intermittent aeration / Contact aeration / Nitrogen removal / Transparency / Rural sewage treatment plants / PACK test / Returned sludge / Poly iron (III) sulfate / 浮遊法 / 嫌気性ろ床槽接触曝気方式 / 窒素処理 / MLSS / オキシデーション・ディッチ / 維持管理 |
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| Research Abstract |
Investigations were carried out on the rural sewage treatment plants, which treatment methods using the contact aeration tanks in combination with the anaerobic filter bed tanks were converted into intermittent aeration method using floating active sludge. The purpose of this study was to determine the optimum operation on these treatment plants for the removal of nitrogen, phosphorus and organic contaminant, and the following findings were obtained.
1. For effective nitrogen removal, there was adequate duration of aeration, which varied with water temperature in treatment tank. Furthermore, total nitrogen in the final effluent water could be reduced within the range front 5 to 10 mg/L approximately, if the duration of aeration would be set adequately.
2. Adequate duration of aeration for effective and stable disposal of nitrogen could be actually determined using the measured values of nitrate nitrogen and ammonia nitrogen obtained by a tiny test for water quality (PACK test ; Kyoritsu Chemical-Check Lab., Corp.) of the final effluent.
3. In the case of small treatment plant, adequate duration of aeration for nitrogen removal would be so decreased by bypass flow through reaction tanks that the transparency of final effluent tended to indicate low values because of the inhibition from organic contaminant disposal that should progress in aerobic condition.
4. Sludge concentration in reaction tanks was increased with MLSS ranging from about 4000 to 5000 mg/L by means of stopping the extraction of excess sludge and increasing the volume of returned sludge at the small plant mentioned above. The results showed that the transparency of final effluent improved considerably at values more than 100 cm.
5. The injection of poly iron(III) sulfate into a reaction tank could decrease the concentration of total phosphorus in final effluent, though it would become necessary to dispose large quantity of excess sludge because the sludge conversion ratio would reach 100%.
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