February 13, 2001

NGK Expands Water Treatment Plant Business : Through Large Ceramic-Membrane Water-Purification Systems

NGK INSULATORS, LTD. (President: Masaharu Shibata, Head Office: Nagoya, Japan) has developed a next-generation water-purification technology using large ceramic-membranes, and is enlarging its water treatment engineering business.

In the 1960's, NGK entered the water purification industry by offering ceramic filter underdrains for rapid filtration ponds. Since then, the company has been expanding its business as a specialized materials/equipment supplier. From 1989, the company started development of water purification systems using ceramic membranes, and from 1991 to 1993, participated in the "MAC 21 Project" - a project sponsored by Japan's Ministry of Health and Welfare for research and development of water purification systems using membranes. In 1996, NGK developed a commercial ceramic-membrane water-purification system for the first time in Japan, and has been selling these systems to small-scale purification facilities for public water systems.

Currently more than 96% of Japan is served by a public water supply, therefore development and introduction of new technology is increasing for the remodeling and renewal of these facilities. NGK newly developed the large ceramic-membrane water-purification system while targeting large savings in cost and space. The company plans marketing efforts to stimulate orders from middle- and large-scale purification plants, and is also supplying ceramic membrane units to water-related machinery and equipment manufacturers. Responding to the changing market, NGK will grow its businesses to establish a position as a major water treatment engineering company. In FY2005, the company aims at 10-billion yen in sales of water treatment facilities, primarily those utilizing the ceramic-membrane purification system.

[NGK Ceramic Membrane Water Purification Systems]
Monolithic and internal-pressure type ceramic-membrane elements of 180mm diameter, 1000mm length and 15m² membrane surface area are employed in the newly developed system. A goal of NGK's development of this new system is large savings of cost and space compared to conventional water purification facilities using ceramic-membrane elements of 30mm diameter and 1000mm length. Micro filtration through 0.1 µm size pores and highly-porous ceramic membranes enable complete elimination of turbidity and impurities such as colloids and bacteria contained in raw water.

[Characteristics of Ceramic Membrane Elements]
1. No chemical degradation and also no deterioration from heat and pressure enable longer operation.
2. Superior thermal/acid resistance and no dissolution of impurities.
3. High mechanical strength prevents damage to the membranes.
4. Superior chemical corrosion resistance allows easy recovery of membrane performance through chemical cleaning compared to polymeric membranes.
5. Used membranes can be recycled as ceramic material for other uses.

[Characteristics of Ceramic Membrane Water Purification System]
1. Enables stable treatment capacity for fluctuating raw water turbidity.
2. Pre- and mid-chlorination is unnecessary, so that generation of trihalomethanes is reduced.
3. Since sedimentation and rapid filtration ponds are not necessary, smaller construction space is possible.
4. Fully automated system, including backwash process, enables unattended operation.
5. Long-life ceramic membranes allow less-frequent replacement of membranes.
6. Dead end filtration enables high recovery rate of water (more than 98%).
7. Small running cost per filtration unit (below 10 yen/m³).
8. Automated treatment process allows simplified maintenance.

In July 2000, the large ceramic-membrane module received a certification by the Association of Membrane Separation Technology, and the large ceramic-membrane water-purification system was certified by the Japan Water Research Center in November 2000.

[Attachment]
A photo of ceramic membrane elements