July 27, 2010


Japan's Leading Water Treatment Technology and its Potential

Keywords: Newsletter 

JFS Newsletter No.94 (June 2010)


The earth is called the water planet: Two thirds of its surface is covered with water. It is said that there are about 1.4 billion cubic kilometers of water on earth. However, the amount of freshwater available for human use as domestic or industrial water amounts to only about 0.8 percent of all water; most fresh water exists as rivers, lakes or underground water.

Japan is counted as a nation of heavy rainfall, as its average annual precipitation is 1,718 millimeters, more than twice the world average of 807 millimeters. With its high population density, however, water resources per capita (cubic meters per capita per year) in Japan are only half the world average; in fact Japan is ranked 91 of 156 countries in the world for water availability per capita.

Still, despite restricted water resources, Japan has maintained continuous economic growth while responding to increased demand for industrial water during its high economic growth periods and demand for domestic water during urbanization. The establishment of efficient water management systems through advancements in water-saving technology has supported Japan's economic growth.

Japan uses water-saving technologies such as membrane technology, as well as technologies for earthquake resistance and leakage prevention. As a result, the country has achieved world-leading, highly-efficient water resource management. The recovery rate of industrial water has increased to nearly 80 percent, while the leakage rate of water supplies is kept at less than 10 percent. Japan's technology and experience constitutes a remarkable strength, and it can contribute to the world by expanding its water-related businesses internationally.

In July 2008, the Water Resource Policy Study Group, organized under the aegis of the Ministry of Economy, Trade and Industry, issued a report regarding the international deployment of Japanese water management businesses and water-related technology. I would like to introduce some specific technologies and case studies, including those cited from the report.
(only in Japanese)

Membrane Treatment Technology

Japan leads the world in membrane water treatment technology. Currently, Japanese manufacturers have about a 60 percent share of the global water treatment membrane market. Japan's global market share of reverse osmosis membrane products, which are highly energy efficient but particularly challenging technically, is nearly 70 percent. At the risk of being a little too technical, let me first outline some membrane technologies, and then introduce some examples of other water treatment technologies.

  • Microfiltration Membrane (MF membrane) A separation membrane to capture particles such as microorganisms and macromolecules that are between 0.1 to 1 micrometers in size. Used in ultrapure water production for semiconductor manufacturing, sterile water production, sterile filtration of wine and beer, etc.
  • Ultrafiltration Membrane (UF membrane) A separation membrane to capture particles and macromolecules between 2 nanometers to 0.1 micrometers in size. Used for removal of colloid macromolecules, ultrapure water production for industrial use, waste water treatment for fiber, pulp and paper industries, etc.
  • Nanofiltration Membrane (NF membrane) A liquid separation membrane to capture particles and macromolecules smaller than 2 nanometers. Used for removal of water hardness components and sulfate ions, and scale component removal for seawater desalination, etc.
  • Reverse Osmosis Membrane (RO membrane) A separation membrane to capture molecules and ions smaller than 2 nanometers. Used for inorganic salts, sugar, amino acid separation, seawater desalination, etc.
Note) micrometer: one thousandth of one millimeter. nanometer: one millionth of one millimeter.

RO membranes are used in the major method employed for desalinating seawater. An RO membrane is semipermeable, allowing a solvent (water) to pass through, but rejecting a solute (salt). For more information on this technology, please refer to the following website.

Reverse osmosis
Animation of seawater desalination with RO membranes
(in Japanese)

Desalinating seawater is not the only application for membrane treatment technology. Water reclamation is becoming increasingly popular around the world as a process for urban sewage treatment. When an RO membrane is used in addition to MF and UF membranes, the quality of the secondary effluent water surpasses that of ordinary tap water. In one example, this filtered water is being supplied to the electronics industry.

Further development of the membrane bioreactor (MBR) method is also underway. In this method, MF and UF membranes are directly soaked into activated sludge treatment tanks of urban wastewater. Present efforts aim at larger-scale use of this method. MBR wastewater treatment facilities are being used in Singapore and Kuwait as well as on a large scale in China. Japanese businesses are expanding their supply of materials and equipment to the world in this area too, centering on membrane components.

Purification of Tap Water

Hamura City is located west of Tokyo, about 45 kilometers away from the metropolitan center. The intake of the "Tamagawa Josui Canal," built in 1653 during the Edo Period to carry drinking water to central Edo, is located here. The source for this drinking water is underground water. Due to the superior quality of this water, the city formerly used only chlorination for tap water. However, after a nearby water treatment facility was infected with cryptosporidium, which can not be killed by chlorine, the city introduced an advanced water purification facility.

This facility started operation in April 2004, and is one of the largest membrane filtering water treatment facilities in Japan. It treats up to 30,000 cubic meters per day and supplies up to 27,500 cubic meters of water to 60,000 people per day. The treatment process can completely eliminate cryptosporidium, by pumping up well water into tanks from whence it passes through a large pore diameter MF membrane unit using the inner pressure of the unit's 10-meter water column (0.1 MPa).

The large pore diameter MF membrane unit was developed to eliminate cryptosporidium 5 micrometers in diameter. The nominal size of the pores is 2.0 micrometers, larger than ordinary MF membranes, normally 0.1 to 0.2 micrometers. The larger pores allow the water to pass using the water pressure without pumps, thus making it energy efficient.

Seawater Desalination

Fukuoka City, an urban area on Kyushu Island in the south of Japan, has often suffered from prolonged water supply restrictions due to water shortages. The area uses 600,000 cubic meters a day, but its local water supply capacity is only two thirds that. With this pressing need to increase the area's water self sufficiency rate, the Fukuoka District Water Agency was established and currently serves six cities, seven towns, one water network agency and one local government office in the Fukuoka area. This agency launched a seawater desalination project that started operation in June 2005.

The desalination facility, the Uminonakamichi Nata Seawater Desalination Center, familiarly called "Mamizu Pia" has a maximum daily production capacity of 50,000 cubic meters, and it is one of the largest desalinization facilities in Japan. It employs cutting-edge technology, described below, and achieves a 60 percent freshwater recovery ratio (ratio of freshwater recovered from seawater).

  • Osmosis intake system: The plant has an intake tank about 20,000 square meters in size located on the seabed about 640 meters offshore in water 11.5 meters deep. This design makes it possible to filter seawater through layers of sand while avoiding both the effects of waves and impacts on fisheries and shipping operations. The water flows into the plant's intake well powered by the difference in water level between the sea surface and the well, and thus the system does not need other power sources for pumping.
  • Pre-treatment: Seawater goes through a UF spiral membrane to remove microorganisms and fine particles. Operational pressure is about 0.2 megapascals (MPa).
  • RO membrane 2-phase method: In an initial high-pressure RO membrane process, pre-treated seawater passes through a membrane module consisting of 1.45 million hollow fibers with an inner diameter of 0.07 millimeters and an external diameter of 0.14 millimeters at a pressure of 8.24 megapascals (MPa). The freshwater discharged from these tiny holes passes through a spiral RO membrane at a pressure of 1.5MPa for uniform water quality.
  • Power recovery: Energy from the pressure of concentrated seawater that is discharged without passing through the membranes is recovered and used to power the high pressure RO pump.

Recycling Sewage Water

Singapore, which depends on imports from Malaysia for most of its water supply, emphasizes securing water as part of its national policy, and promotes seawater desalination and sewage water recycling. An R&D project to develop recycled water, called NEWater, was launched in 1998. The recycled water is processed from water that goes through regular treatment at sewage water treatment facility, followed by a 3-phase purification process and advanced treatment to reach a drinkable level.

An initial MF membrane treatment followed by RO membrane treatment removes inorganic ion and viruses, making the treated water equivalent to pure water. Finally, the water is disinfected by ultraviolet radiation. Since February 2003, NEWater is being mixed into ordinary reservoirs (initially at a ratio of 1 percent); this reservoir water then enters the water supply after the normal purification process. NEWater is also being used as industrial water.

Until 2006, 278,000 cubic meters of water were processed at the NEWater facilities per day. More than 90 % of RO membranes installed in these facilities were supplied by Japanese manufacturers (Nitto Denko Corporation and Toray Industries). Toray Industries is also planning to provide RO membranes for facilities that will produce 228,000 cubic meters per day, which are scheduled to start operation in 2009 and 2010.


Water-related businesses are expected to grow globally over the mid- to long-term. According to the Council on Competitiveness-Nippon (COCN), in 2025 the market size for such businesses will be about 1 trillion yen (about US$10.75 billion) for material supplies, to about 10 trillion yen (about US$107.52 billion) for engineering, procurement and construction, and about 100 trillion yen (about US$ 1.07 trillion) for the entire market including business operation and management.

Japanese water projects have so far been conducted as public works. Therefore, private companies have limited know-how about business operation and management and lag behind European companies, including the so-called Water Barons. A council has been established to integrate the strengths of advanced fabric supply technologies, facility building and the management strengths of Japanese businesses with management know-how developed by Japan's public sector.

In May 2010, a Japanese business consortium acquired the second largest waterworks company in Australia. Through a consulting contract, the technology and know-how of the Bureau of Waterworks of the Tokyo Metropolitan Government will be applied in operating the business. The Tokyo Metropolitan Bureau of Waterworks adopted a management plan in January 2010; one of the major measures set out in this plan was to make an international contribution using existing technologies. The international expansion of Japan's water business is about to begin.

Written by Kiyoshi Koshiba

See also:
Japanese Technology to Help Address Global Water Problems