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Release: December 2, 2004

A receipt of an order for the nation's largest ceramic
membrane municipal drinking water treatment system

A consortium of Ebara Corporation (President & Representative Director: Fumio Shimakawa; Head Office: Ohta-ku, Tokyo, Japan) and NGK INSULATORS, LTD. (President & COO: Shun Matsushita; Head Office: Nagoya, Japan) has received an order for its ceramic membrane system for a water treatment plant from Fukui Prefecture. It is scheduled to be completed by the end of 2006 making it Japan's largest water treatment plant using membrane filtration including organic membrane filtration.

The order is for the installation of a water treatment system for Oushio Water Treatment Plant (tentative name; location: Ooshio-cho, Takefu, Japan) which is one of the Fukui prefecture's projects to supply drinking water to the Hino River district. This project plans to supply up to 51,900 m3 potable water per day to approximately 180,000 residents in two cities and four towns, including Takefu and Sabae, located in Tannan Area, the central part of Fukui. This is the project's first-stage construction to build a water treatment plant which will be capable of supplying 38,900 m3 drinking water per day.

As Fukui Prefecture planned the construction, they had considered introducing a membrane filtration system, a state-of-the-art water purification technology which substitutes for a conventional sand filtration system; and had conducted field experiments evaluating five leading membrane filtration systems. As a result, the ceramic membrane filtration system was selected because it provides enhanced safety and a longer lifetime with low-running costs.

The amount of this order is 3.41 billion yen (tax excluded). 18 units of membrane filtration equipment are to be installed. Each equipment is consisted of 100 large-scale ceramic membrane elements each of which has a diameter of 180 mm, a length of 1,000 mm with a membrane surface area of 15 m2; which means a total of 1,800 ceramic membranes are used. The system is expected to be completed and be fully operational by the end of 2006. When completed, this will be Japan's largest water plant utilizing membrane filtration including organic membrane filtration.

Taking this order as an opportunity to expand the company's share of ceramic membrane in the market of membrane filtration water purification, NGK will aim to achieve the sales of 10 billion yen in the year of 2009.

Ceramic membrane water treatment system

Ceramic membrane water treatment system

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1. Background

Many of about 15,000 water treatment plants in Japan were constructed from the 1950s to 1970s. It is expected that there will be a growing demand for reconstruction and renewal projects as the plants age and that a development and an introduction of new water treatment technologies including a membrane filtration system will be accelerated replacing a conservative sand filtration system.
In 1989, NGK started developing a water purification system using a ceramic membrane focusing on safety and durability of ceramics. NGK participated in projects sponsored by Japan's Ministry of Heath and Welfare (renamed the Ministry of Heath, Labor and Welfare) including the "MAC 21 Project" (1991 to 1993) for the research and development (R&D) of a drinking water treatment system employing the membrane and the "ACT 21 Project" (1997 to 2001) for the R&D of a high-efficient water purification technology. At present, NGK is involved in the project called the "e- Water" (2002 to 2004) for the R&D of a water purification technology with a low environmental impact to develop a technology of high-capacity membrane filtration.
In 1996, NGK developed the Japan's first ceramic membrane water treatment system applying its original ceramic membrane (30 mm in diameter, 1,000 mm in length) which has been successfully utilized for microfiltration in the medical and food industry. This system has been sold to small-scale water treatment plants such as a small water supply-system.
In 2000, NGK developed a water purification system using large ceramic membrane elements (180 mm in diameter, 1,000 mm in length) aiming at a smaller footprint with substantially lower costs. The company started its marketing efforts in full scale to stimulate orders from the mid to large-size municipal water treatment plants, and these efforts paid off in 2002 when NGK successfully delivered Japan's largest ceramic membrane water treatment system to the Bureau of Waterworks, Tokyo Metropolitan Government. NGK constructed a mass production factory for the ceramic membrane in Kani-gun, Gifu, Japan in preparation for its increasing demand and has started its manufacturing in October 2003.

2. Outline

Compared to polymeric membranes such as hollow fiber, ceramic membranes have the higher mechanical strength to prevent damage to the membrane ensuring safe supply of water, and feature superior durability and lower operating cost. NGK's water treatment system incorporates the internal-pressure type, monolithic ceramic membrane element of 180 mm in diameter, 1,000 mm in length with a membrane surface area of 15 m2. Microfiltration by porous ceramic membranes, with a pore size of 0.1 micron, enables the removal of contaminants including turbidity of raw water (river water etc.), E. coli bacteria and/or cryptosporidium (pathogenic microbe).

1.Characteristics of Ceramic Membrane Elements

  • Free of chemical degradation and deterioration by heat and pressure resulting in longer operation life
  • No elution of impurities due to superior heat and corrosion resistance
  • High mechanical strength with no membrane breakage
  • Easy recovery of membrane performance through chemical cleaning due to superior chemical resistance
  • Recyclable used membranes as raw ceramic materials for other uses

2.Characteristics of Ceramic Membrane Water Treatment System

  • Unaffected by rapid fluctuation of raw water turbidity keeping the treatment performance always stable
  • Smaller footprint because no sedimentation basin and rapid sand filter is necessary
  • A fully automated system, including the backwash process, allows unattended operation
  • Ceramic membranes have longer lifetime requiring fewer replacements.
  • The dead-end filtration with a high water recovery rate (98% and above)
  • Low running cost per unit volume of filtrate
  • Capable of treating various types of raw water: the system, coupled with supplementary processes, is able to remove soluble iron, manganese, chroma and odor that cannot be removed by the membrane filtration alone

In September 2002, this ceramic membrane water treatment system received a certification as a membrane module for potable water treatment from Association of Membrane Separation Technology of Japan. In December 2003, it was also certified as the membrane filtration equipment for potable water treatment by Japan Water Research Center.

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