2003 Fiscal Year Final Research Report Summary
Development of a novel sewage treatment system for developing countries.
| Project/Area Number |
13355022
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Civil and environmental engineering
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| Research Institution | Nagaoka University of Technology |
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Principal Investigator |
OHASHI Akiyoshi Nagaoka, University of Technology, Assistant Professor, 工学部, 助教授 (70169035)
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| Co-Investigator(Kenkyū-buntansha) |
HARADA Hideki Nagaoka, University of Technology, Professor, 工学部, 教授 (70134971)
IMACHI Hiroyuki Nagaoka, University of Technology, Assistant, 工学部, 助手 (20361933)
UEMURA Shigeki Kisarazu National College of Technology, Associate Professor, 環境都市工学科, 助教授 (60300539)
OKUI Hiroyuki Association for Rainwater Storage and Infiltration Technology, Researcher, 技術第一部, 研究員(研究職)
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| Project Period (FY) |
2001 – 2003
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| Keywords | Developing countries / Sewage treatment / Low cost / Methane / Molecular biology / UASB / DHS / Nitrification and Denitrification |
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| Research Abstract |
Current sewage treatment system such as activated sludge is not suitable in developing counties due to high costs and high energy requirement. An "appropriate technology" of sewage treatment must be developed for developing countries. Recently UASB is attractive technology for sewage treatment in developing countries since it guarantees low construction and operational cost, produce energy as methane and less amount of sludge. However UASB alone can not meet discharge criteria, so that further option is needed to polish up UASB effluent without losing UASB strong point. As a proper system, we have proposed DHS (Down-flow Hanging Sponge) reactor. The principle of DHS is the use of a polyurethane sponge as a medium to retain biomass. The concept is similar to that of tricking filter, except that the packing material is sponge, which has a void space of more than 90%, resulting in a significant increase in entrapped biomass and thus longer solid retention time (SRT). As the sponge in a DHS is not submerged and freely hung in the air, oxygen is dissolved into the wastewater when it flows down the reactor. Therefore there is no need for external aeration or any other energy inputs. Moreover, production of excess sludge from DHS is negligible as longer SRT provides considerable time for autolysis of sludge in the system itself.
Demonstration-scale DHS reactor with a treatment capacity of 1,000m^3・d^<-1> has been installed since 2002 by Indian government in India. We monitored this system as well as last year. DHS reactor has been operated at HRT of 1.49hr. As a long-term experimental period, we can see the excellent performance of DHS in terms of BOD, COD and fecal coliform removal which were 93%, 88% and 2 order, respectively without any problem. As a these result, a real scale DHS is planned on constructing in Agra city, India by Indian government.
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