Grant-in-Aid for Scientific Research (A)
|Allocation Type||Single-year Grants |
Civil and environmental engineering
|Research Institution||UNIVERSITY OF MIYAZAKI |
YOKOTA Hiroshi University of Miyazaki, Faculty of Engineering, Professor, 工学部, 教授 (90037888)
TANABE Kimiko UNIVERSITY OF MIYAZAKI, Material Research Center, Lecture, 産学連携支援センター, 講師 (00179805)
SATIU Tsutomu University of Hokkaido, Circulated Environment system, Associate Professor, 大学院工学研究科環境循環システム専攻, 助教授 (10313636)
SEZAKI Mitsuhiro UNIVERSITY OF MIYAZAKI, Faculty of Engineering, Associate Professor, 工学部, 助教授 (80136803)
DOTE Yutaka UNIVERSITY OF MIYAZAKI, Faculty of Engineering, Associate Professor, 工学部, 助教授 (30264360)
OOE Kaoru UNIVERSITY OF MIYAZAKI, Faculty of Engineering, Research Assistant, 工学部, 助手 (00315350)
宮武 宗利 宮崎大学, 工学部, 助手 (40315354)
馬場 由成 宮崎大学, 工学部, 教授 (20039291)
|Project Period (FY)
2004 – 2006
Completed(Fiscal Year 2006)
|Budget Amount *help
¥26,910,000 (Direct Cost : ¥20,700,000、Indirect Cost : ¥6,210,000)
Fiscal Year 2006 : ¥9,490,000 (Direct Cost : ¥7,300,000、Indirect Cost : ¥2,190,000)
Fiscal Year 2005 : ¥8,970,000 (Direct Cost : ¥6,900,000、Indirect Cost : ¥2,070,000)
Fiscal Year 2004 : ¥8,450,000 (Direct Cost : ¥6,500,000、Indirect Cost : ¥1,950,000)
|Keywords||Arsenic / Groundwater / Arsenic removal / Treatment of sludge / Natural treatment / Cement solidification / Micro-organism|
We have established the design chart of the arsenic removal unit, Gravel Sand Filter (GSF), by examining the arsenic removal performance of 4 GSFs installed in Bangladesh these 4 years. These GSFs are community-based units and have supplied arsenic-safe water to villagers in these years. GSF is composed of gravel tanks and sand tank. The arsenic in groundwater is to be settled in the gravel voids of gravel tanks by co-precipitation with iron, which exits naturally in groundwater with higher concentration.
The iron and arsenic in groundwater are first to be oxidized at the inlet tank of GSF. The aeration, contact between iron and arsenic, and the concentration of competition ions as phosphate are key points for the performance of GSF. The design methods for these poi its are proposed in this research. The performance of GSF is usually O.K with 10 value of ratio, Fe/As, in groundwater. The ratio of Fe/As should be, however, bigger 30 for the groundwater with high concentration of phosphat
e. The box filled with large amount of used iron nails is to be set in the inlet tank in the design chart of GSF, when GSF has to be installed at the cite where the groundwater has less ratio of 30 under the higher concentration of phosphate.
Arsenic sludge from GSF is to be settled in the sludge tank installed in the GSF cite through draining. The supernatant of the sludge tank is flowed to the artificial pond where the natural treatment of arsenic is examined. The settlement of the sludge tank is solidified by cement. The 90% of arsenic in the settlement is shut out without cement but the arsenic concentration of the leaching test was 0.05〜0.65mg/L, showing beyond values of standards 0.05mg/L in Bangladesh. The leaching tests for the 2% mixing of cement show 0.05〜0.11mg/L, which is less than the second standard for land contamination in Japan, 0.30mg/L..
The pH of the tests shows 10.5-10.9.
The treatment method, here, is to mix the sludge settlement with 2% cement and deposit without contact to water until the establishment of waste treatment management in Bangladesh.
We have estimated the accumulation of arsenic at the bottom of the artificial pond and looked for the micro-organism in the bottom soil which can change the inorganic arsenic to organic one. We can detect some of Monomethylarsine(MMA) and
Dimethylarsine(DMA) in both of sludge tank and artificial pond. And, the micro-organism strong to arsenic was confirmed, which can live under the condition of arsenic concentration of 1000mg/L. Less