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Environmental Guide

The sewerage plays a vital role in ensuring a safe and pleasant urban life by improving the living environment and preserving the water quality of rivers and sea through appropriate treatment of sewage and drainage of rainwater.
On the other hand, in order to build up a sustainable and recycling-oriented society so as to hand down a pleasant global environment to the next generation, we are making efforts to reduce the emission of greenhouse gas from the sewerage and are promoting recycling of resources and energy by utilizing the energy, sludge and reclaimed water generated in the process of sewerage treatment.
This brochure, "Environmental Guide-Bureau of Sewerage," contains the contents of "Earth Plan-2004" (drawn in September 2004), a plan designed for preventing global warming in sewerage, and introduces the measures taken by the Sewerage Bureau for reducing environmental load.


  1. Reduction of Greenhouse Gas
    Outline of Earth Plan-2004
    High-temperature Sludge Incineration
    NaS Battery
  2. Utilization of Energy
    Wastewater Heat (heating and cooling)
    Sludge Incineration Waste Heat (heating and cooling)
    Sludge Incineration Waste Heat (power generation)
    Sludge Gasification (scheduled)
    Power Generation using Biomass Energy
    Micro-hydro Power Generation
  3. Utilization of Sludge
    Utilization as Fuel for Thermal Power Plant
    Various Materials
  4. Utilization of Reclaimed Water
    Water for Miscellaneous Use viz. Toilet Flush, etc.
    Restoration of Waterways (Environmental Water)
    Water for Watering Plants at Drought and Water for Fire Fighting
  5. Effective Use of Facilities and Space
    Utilization of Above-ground Space
    Inside of Sewerage Pipes (Optical Fiber)
  6. Other Effective Use
    Using Surplus Soil from Excavation
  7. Environmental Report

Schematic of "Environmental Guide - Bureau of Sewerage"

Measures for preventing gloval warming Earth Plan 2004.... and so on.

Reduction of Greenhouse Gas

The term "greenhouse gas" refers to gasses like CO2, etc. contained in air that seals up solar heat and causes the earth surface to get warm. The Sewerage Bureau drew up the"Earth Plan-2004", in September 2004, a plan for preventing global warming, and is promoting measures to reduce the emission of greenhouse gas.

Mechanism of Global Warming

Utilization of Renewable Energy

Different from the fossil fuel, the energy that can be renewed and reused through natural phenomena is called renewable energy, such as hydraulic power, wind power, solar light, biomass (livestock excremental and urine, sewage sludge, etc.).
The Sewerage Bureau is actively engaged in making effective use of all kinds of renewable energy during the process of sewage and sludge treatment.

Transition of renewable energy utilization rate

Utilization of Sludge

The sludge from the wastewater (sewage) treatment is all subjected to incineration, with approximately 60% of the incinerator ash recycled as cement material, lightweight aggregate material and construction material super ash for civil engineering works and the rest put to disposal by sanitary landfill. Since Tokyo has restricted space for such disposal, efforts are made to put the sludge to further recycling.

Volume of generated sludge and recycling rate

Utilization of Reclaimed Water

A huge volume of water is consumed everyday in Tokyo, with the sewage water treatment volume in 20 Water Reclamation Centers amounting approximately to 5.8 million m3 per day. The reclaimed water after filtration and disinfection is used for toilet flushing, streams augmentation, etc. as an important water resource of Tokyo.

Transition of treated wastewater volume and re-utilization rate

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