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Release: July 4, 2001

NGK Takes First Order for Large Ceramic-Membrane Water-Purification Systems

NGK INSULATORS, LTD. (President: Masaharu Shibata, Head Office: Nagoya, Japan) has taken its first order from the Tokyo Waterworks Department for a next-generation water-purification system using large ceramic-membrane technology. It will be the nation's largest water-purification system using ceramic-membranes.

The large ceramic-membrane water-purification system will be used as a membrane-filtration system in the Ohkuno Water Purification Plant in Hinode-cho, Nishitama-gun, Tokyo. This system consists of four membrane units using large ceramic-membrane elements which are 180 mm in diameter and 1,000 mm in length. The total amount of water purified is estimated to be 3,400 m3 per day. The value of this first order is ¥380 million. Installation is expected to be completed in fall, 2002, and operation will start promptly.

From 1989, the company started development of water-purification systems using ceramic-membranes, focusing on safety and durability of ceramics. From 1991 to 1993, the company participated in the "MAC 21 Project" - a project sponsored by Japan's Ministry of Health and Welfare (currently Ministry of Health, Labor and Welfare) for research and development of water-purification systems using membranes. In 1996, NGK developed a commercial ceramic-membrane water-purification system using NGK's originally developed ceramic-membrane filters (30 mm in diameter) for the first time in Japan, and has been selling these systems to small-scale purification facilities for public water systems. Compared to polymeric-membrane, ceramic-membrane provides safer water, since its superior mechanical strength prevents damage to the membranes and also allows operation with lower running cost. However, there was a concern of its relatively high initial cost to be solved. NGK, then, newly developed the large ceramic-membrane (180 mm in diameter) targeting large cost savings, and have made marketing efforts to stimulate orders from middle- and large-scale purification plants. These series of efforts led up to this successful first order for a large ceramic-membrane water-purification system.

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. Based on this first order for a large ceramic-membrane water-purification system, NGK expects to continue its growth in these businesses until it establishes 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 water-purification system. The company is also supplying ceramic-membrane units to water-related machinery and equipment manufacturers.

NGK Ceramic-Membrane Water-Purification Systems

Monolithic and internal pressure type ceramic-membrane elements 180 mm in diameter, 1,000 mm in length and 15 m2 of membrane surface area are employed in the large ceramic-membrane water-purification system. A goal of NGK's development of this new system has been large savings in cost and space compared to conventional water-purification systems using ceramic-membrane elements 30 mm in diameter and 1,000 mm in length. Micro filtration through 0.1 µm size pores and highly-porous ceramic-membranes enable complete elimination of impurities such as turbidness, E-coli bacteria and cryptosporidium (pathogenetic protozoa) contained in raw water.

Characteristics of Ceramic-Membrane Elements

  1. Longer operation due to no chemical degradation and also no deterioration from heat and pressure.
  2. Superior thermal/acid resistance and no dissolution of impurities.
  3. High mechanical strength prevents damage to 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 turbidness.
  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 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.

A photo of ceramic-membrane elements

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