A New O&M Approach for both Improvement of Water Quality and Reduction of Greenhouse Gas Emissions in Wastewater Treatment Plants

Since approximately 1% of power consumption of the Tokyo metropolitan area is consumed for the sewage treatment, Bureau of Sewerage, Tokyo Metropolitan Government has been putting its efforts into reducing the power consumption to reduce greenhouse gas emissions. Furthermore, further power reductions are required because of the significant increases of electricity rates due to the shut down of nuclear power plants and increase in the cost of the fuel for thermal power generation after the Great East Japan Earthquake. However, an excessive power reduction may lead to the deterioration of the water quality. Thus, the bureau of sewerage has devised and implemented the “Two Axis Management Method” as a tool to achieve both the water quality improvement and power consumption reduction which are in trade-off relationship.