“Technology Demonstration Project for Final Sedimentation Tank Treatment Capability Enhancement” Adopted for 2017 B-DASH Project
“The Technology Demonstration Project for Final Sedimentation Tank Treatment Capability Enhancement” has been adopted for the 2017 Breakthrough by Dynamic Approach in Sewage High Technology Project (B-DASH Project)*1 carried out by the Ministry of Land, Infrastructure, Transport and Tourism. This Demonstration Project has been proposed by a three-party joint research alliance formed by Matsumoto City (mayor: Akira Sugenoya), Japan Sewage Works Agency (president: Toshihiro Tsujihara; head office: Bunkyo-ku, Tokyo; hereinafter “JS”), and METAWATER Co., Ltd. (president: Yasushi Nakamura; head office: Chiyoda-ku, Tokyo).
In recent years, the time has come for many sewage facilities to have their functions upgraded, and those with an inadequate processing ability need to add processing sequences, etc. However, as the inflowing water volume is expected to decrease in the future due to depopulation, there is an apparent need to use low-cost upgrading technologies that require a smaller financial burden and to avoid adding processing sequences for tentatively strengthening processing ability.
Under this proposal, a “filtration section” is incorporated into a final sedimentation tank (hereinafter “FST”), helping to limit an increase of SS*2 density (quantitative enhancement) in water that overflows out of the FST when processing water volume increases. This proposal also aims to enhance the quality of water overflowing from the FST (qualitative enhancement) when facilities are operated using the planned volume of processing water. As a result, construction costs can be considerably reduced compared to conventional cases where processing sequences or a rapid filtration equipment are added to the FST.
*1 B-DASH is the abbreviation for Breakthrough by Dynamic Approach in Sewage High Technology Project.
This is a demonstration project carried out by the Ministry of Land, Infrastructure, Transport and Tourism to help reduce sewage business costs and create renewable energy, etc. by accelerating the research,
development and practical application of new technologies, and to support overseas water business
development by Japanese companies.
*2 SS: Suspended solid
2．Characteristics of technology demonstrated1) Enhance/stabilize the quality of processing water using a filter.
2) No need to change the existing water level because the pressure loss of the filtration section is tens of mmAq
3) Sequential operation is possible due to automatic air backwash.
4) Easy maintenance and management because there is no underwater drive section.
5) Considerable reduction of construction period with prefabrication
3．Examples of using proposed technology1）Elimination of tentative final sedimentation capability shortages that arise when facilities are upgraded
[Quantitative enhancement (1)]
Despite a small number of processing sequences, inadequate ability of existing facilities, and insufficient
processing ability that arises when facilities are upgraded or suspended for a few months to
approximately one year, these are not adequate reasons for adding final sedimentation processing
sequences including civil engineering frameworks.
2）Increasing processing water volume over the mid-term by integrating processing facilities and sequences
[Quantitative enhancement (2)]
The water inflow volume is anticipated to decrease due to depopulation. There is a need to handle
such asituation without adding processing sequences even when water volume increases over the
mid-term immediately after integration.
3）Enhancement and stabilization of the quality of discharged water [Qualitative enhancement]
Need to prevent tentative deterioration of processing water quality occurring at the time of an increased
water flow due to rain, peak water flow, etc., or to enhance the quality of discharged water constantly.
4．Technological performance goals[Quantitative enhancement]
- Technological performance: Increase processing water volume up to twofold without a deterioration of
processing water quality.
- Technological performance: Enhance the quality of processing water (planned processing water volume)
to a level equivalent to that of rapidly filtered water.
5．Project outlineMatsumoto City provides a demonstration field and proclaims in its Comprehensive Plan that it aims to ensure a clean, comfortable living environment and preserve the water quality of rivers, etc. through appropriate maintenance and management of sewage systems, while actively striving to extend the useful lives of sewage facilities. METAWATER is a total solution provider engaging in the water environment business and aiming to recycle water, resources, and energy using its advanced core technologies.
METAWATER aims to develop its sewage business and establish innovative technologies that help ensure continuity through the cooperation of three parties including Matsumoto City and JS in future.
Project participants: Matsumoto City, Japan Sewage Works Agency, METAWATER Co., Ltd. (joint research alliance)
Demonstration field: Ryoshima Purification Center (3-1 Ryoshima, Matsumoto City, Nagamo Prefecture)
Current processing method: Standard active sludge method