Press Releases

Recently, an increasing number of cases of soil/groundwater contamination with chlorinated ethenes, such as trichloroethene, have been treated by bioremediation technology using anaerobic microbes. Bioremediation can treat even the ground under factories or buildings and is about one-tenth of the cost of excavation. The most commonly used bioremediation technology is called "biostimulation", which uses existing degrading microbes to clean up contaminated land. However, this approach cannot be used at sites not inhabited by chlorinated ethene-degrading microbes (approx. 30% of the national land contaminated with volatile organic compounds).

To address this problem, from August 2002 to February 2007, we participated in the New Energy and Industrial Technology Development Organization’s (NEDO’s) project "Development of Technologies for Analyzing and Controlling the Mechanism of Biodegradation and Processing" and focused on developing a technology of injecting a pre-grown culture of degrading microbes into the ground (bioaugmentation).

After a review by the Ministry of Economy, Trade and Industry and the Ministry of the Environment from March 2006, the ministries endorsed our technology for in situ degradation and detoxification of chlorinated ethenes in June 2008 for the first time in Japan to comply with the "Guidelines on Use of Microbial-based Bioremediation."

• 1)Allows bioremediation to be used also for sites not inhabited by chlorinated ethene-degrading microbes.
• 2)Almost halves the clean-up time compared with the conventional biostimulation approach, which took almost a whole year, by injecting chlorinated ethene-degrading microbes (in-house comparison).
• 3)Reduces the purification cost by up to 30% compared with the conventional biostimulation approach (in-house comparison).
• 4)Ensures thorough degradation of chlorinated ethenes to harmless ethene by using the microbial consortium dominated by vinyl chloride degrading microbes (Dehalococcoides), whereas the conventional biostimulation approach sometimes failed to completely degrade chlorinated ethenes, a soil contaminant, depending on the kind of degrading microbes, resulting in the accumulation of highly toxic vinyl chloride, an intermediate product of degradation.

1)Outline of the Guidelines

The Guidelines were established in March 2005 jointly by the Ministry of Economy, Trade and Industry and the Ministry of the Environment to ensure that bioaugmentation is safely implemented. Specifically, the Guidelines stipulate basic requirements for proper safety assessment/control procedures, in order to ensure the sound growth of the bioremediation industry and environmental conservation through wider application of bioremediation technology.

2)Our compliance with the Guidelines

Our technology is the third to be approved to comply with the Guidelines but is the nation’s first of these to be approved for in situ degradation and detoxification of chlorinated ethenes.
As noted, Dehalococcoides, the only microbe that can degrade chlorinated ethenes to harmless ethene, is the key microbe for our technology. However, as it is difficult to achieve pure culture of the microbe, we needed to establish a "microbial consortium" including other microbes that supply Dehalococcoides with hydrogen (energy source for growth) in order to use the microbe. We developed a unique enrichment procedure to maintain Dehalococcoides firmly (patent pending), and rigorously confirmed the safety of the culture. As a result, we succeeded in establishing a microbial consortium containing Dehalococcoides that satisfies the requirements of the Guidelines, thus making bioaugmentation using Dehalococcoides feasible for the first time in Japan.