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General Manager of Business Relations,
Business Incubation Division, Hitachi, Ltd.
The threat to ecosystems from ballast water discharged by ships is a problem in harbors around the world. Using original technology, Hitachi has developed a ballast-water purification system that minimally impacts the environment.
Test operation in Tokyo Bay
When a tanker or freighter unloads, it rises in the water and needs to add ballast for stability. For this reason, ships have ballast tanks that are filled with seawater. A 300,000-ton tanker takes on about 100,000 tons of seawater, enough to fill over 50 fifty-meter pools. But the ship releases that water when it takes on new cargo, discharging foreign organisms that can wreak havoc on the local ecosystem.
Ballast-Water Purification System
I learned of the gravity of ecosystem damage from ballast water when speaking at the "Japan Today" seminar in the Middle East. In response, I devised a ballast-water purification system using a technology I had developed in 2001 that uses a superconducting magnetic separator to coagulate and remove the bluegreen
algae*1 that grows in lakes and ponds, caused by excess nutrients.
The principle is the same as the one used to collect iron particles with a magnet. Adding iron powder and long strings of polymers to seawater and then agitating it causes organisms in the water to coagulate into small clumps (or flocs), which can then be collected with a magnet.
A superconducting magnet was originally used, but while the magnetic field was strong, the cost was high, and maintaining the proper temperature was difficult. These problems were overcome by using Hitachi Metals' compact, low-maintenance permanent magnet. Hitachi Plant Technologies also participated in the project, contributing expertise in water treatment. By trial and error, we exceeded the standards that the International Maritime Organization (IMO) had set: only 5 organisms between 10 μm and 50 μm per milliliter, no organisms over 50 μm, and no E. coli bacteria.
The IMO requires the phasein of ballast-water treatment equipment, with all ships fitted by 2017. The usual way to meet the IMO's water-quality standard is to use sterilization. However, this approach raises concerns over secondary pollution caused by residual chlorine or other disinfectants released into the ocean. In addition, dead organisms build up in the tanks causing rust. In contrast, Hitachi's coagulation and magnetic separation method collects the seawater organisms in flocs, without secondary pollution. Hitachi's system has attracted much attention in Europe, where there is deep interest in "green" ships.*2
At present, a land-based test is being conducted in Tokyo Bay, with the goal of onboard testing in 2008. Hitachi bioscience researchers are carefully evaluating the ecological impact with the goal of commercialization in 2009.
This technology can also be applied to purification of the water discharged when oil is extracted from oil sands, and is currently being eyed as a promising alternative to conventional methods. Testing is already underway in Canada.
(Published in July 2007)