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News Release
05.21.2013

Technology proposed by Ikeda City and METAWATER for an “Innovative Sewage Sludge to Energy Conversion System with O ptimized Dehydration, Combustion, and Power Generation “ selected for B-DASH Project
- For the future from "A City Where Things Begin" — From energy consumption to energy creation -

A "Demonstration project for an innovative sewage sludge energy conversion system with optimized dehydration, combustion and power generation" proposed by Ikeda City, Osaka (Mayor: Osami Kominami) and METAWATER (President: Tomoyasu Kida. Main Office in Chiyoda ku, Tokyo) was selected for implementation as part of the Breakthrough by Dynamic Approach in Sewage High Technology Project (the B-DASH project) undertaken by MLIT.

<Social needs to be met>

Innovative sewage treatment plants meeting the need for optimized energy conservation, energy creation, and lower construction and maintenance costs are now required to cope with such problems as decreasing population, a tight energy supply-demand situation, and global warming. The proposed technology presents options for effectively addressing the many issues in sewage sludge treatment.

In its Water Supply and Sewerage Vision announced in 2011, Ikeda City uses as a motto, "Clear Water for the Future." This expresses the city's goal of creating a sound water environment to leave to the next generation. METAWATER is an engineering company for water environments, which strives to create water/resource/energy cycles by means of advanced core technologies. For the future, Ikeda City and METAWATER intend to cooperate to establish innovative technologies contributing to full optimization of treatment plants to ensure the development of sustainable sewage works.

<Outline of the project>

In this project, actual-scale installed facilities will be set up to demonstrate an electric power generation system using combustion of a valuable biomass resource, the sludge discharged from the sewerage system.

The system includes the following innovative technologies: an autonomous centrifugal dewatering machine (ACD); a low excess-air-ratio incinerator (LEI); and a dual-heat source binary power reclaimer (DBPR)." Optimal utilization of these technologies as a system helps maximize power generation at the same time it greatly reduces greenhouse gas emissions as well as construction and maintenance costs.

Project operator: Joint study team established by Ikeda City and METAWATER
Demonstration field: Ikeda City Sewage Treatment Plant (Daihatsu-cho 3-1, Ikeda City, Osaka)
Demonstration scale: 25 tons of sludge cake per day

<Project plan>

The demonstration facilities will be constructed for demonstration in the above field.

【Basic concept】

The system aims at "breakaway from the sludge treatment system consuming large amount of energy" while focusing on maximizing the energy-saving, cost-saving, and energy creation (power generation) effects of the whole system by upgrading/efficiency improving and coordinating dehydration, combustion, and power generation functions of sewage sludge.

【Innovative technologies】

(1) Three characteristic individual technologies
■Autonomous centrifugal dewatering machine (ACD)
This technology employs a low-power, high-efficiency centrifugal dehydrator applied in many fields, which controls dosage, centrifugal force, etc. to obtain the required sludge characteristics (water content, etc.) to minimize consumption of power and chemicals.

■Low excess-air-ratio incinerator (LEI)
In addition to the tested multi-layer combustion technology with air supplied from multiple locations, stable operation with low air ratios can be achieved through full utilization of control technology. This technology reduces exhaust gas emissions and enables downsizing, reduction of electric power and auxiliary fuel consumption. It also contributes to lower maintenance costs and reduction of greenhouse gas emissions (N2O, CO2, etc.).

■Dual-heat source binary power reclaimer (DBPR)
This technology was developed by improving power generation from low temperature difference technology, a well-known technology in geothermal power generation, on the basis of conditions unique to waste heat generated in the incineration of sewage sludge. Two types of waste heat radiate from the sewage sludge incinerator: latent heat (low-temperature waste heat) recovered in the scrubbing tower, and sensible heat (high-temperature waste heat) from emitted gas. Two-heat-source power generation technology that efficiently utilizes both types of heat helps maximize power generation.

(2) Automatic trade-off adjusting function (ATF)
Coordinating the three characteristic innovative technologies described above will maximize (optimize) the benefits gained from introducing the system.

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