May. 12, 2004
Obayashi, Toyota Develop Soil-Remediation Technology
Ministry of Economy, Trade, Industry Certifies Biotechnology-based Solution
Tokyo ― OBAYASHI CORPORATION (Obayashi) and TOYOTA MOTOR CORPORATION (TMC) announced today that they have jointly developed a soil remediation technology, the first in Japan, which uses microbes to treat soil contaminated with pollutants such as the typical soil pollutant trichloroethylene (TCE).
Against a background of growing soil contamination in recent years, Obayashi has taken increased action in the area of soil remediation and has a strong record in microbial soil remediation, including the biotreatment of oil-contaminated soil in Kuwait. Obayashi has also been promoting the development of environmentally considerate and effective technology for the remediation of soil contaminated with TCE.
Since its foundation, Toyota has sought to contribute to society by "making things" and "making automobiles". In recent years, as it takes reinforced company-wide action on environmental issues, TMC has undertaken biotechnology-based research and development with the aim of achieving a socially useful result. As TMC considers the effective use of microbes important, it has pursued research into TCE-degrading microbes.
To realize the development of the technology announced today―a pile stock bioremediation system―the two companies brought together their respective technologies, with TMC discovering the TCE-degrading microbe and developing the culture technology, while Obayashi took charge of applying engineering techniques to the microbes.
There are a variety of conventional technologies for the remediation of soil contaminated with TCE or other substances, each of which, however, requires a lengthy remediation period with relatively high costs and entails other issues such as those relating to the safety of the chemicals used. There was, thus, a need for a remediation technology that was fast acting, low in cost and safe.
The new technology developed involves mixing into the contaminated soil a high-performance TCE-degrading microbe and a soil-enriching agent that improves the action environment of the microbes. (Please see the following diagram.)
Further, the TCE that is vaporized during mixing and other stages of the remediation process is recovered and treated, so that no pollutants are released into the atmosphere.
The remediation period of one to four weeks with conventional technology is shortened to approximately 24 hours. Moreover, as remediation can be performed simply by layering the soil with the microbes mixed into it, costs can be reduced to roughly 70% of those when using conventional technology.
The microbes used are selected from nature, with no gene recombination involved. Safety has been confirmed in a variety of tests. As no chemical substances are used in the remediation process, there is no environmental impact. The new remediation technology thus has the advantages of safety and environment-friendliness and also achieves a shortening of the remediation period and a reduction in cost. Its efficacy was also confirmed in full-scale validation tests conducted in autumn last year.
Use of the newly developed technology in TCE-contaminated soil was certified by the Ministry of Economy, Trade and Industry on April 9 under the ministry’s Recombinant DNA Technology Industrialization Guidelines "Use of Type 2" (open space based) following an inquiry that included the invitation of comments from the public, making it the first such certification in Japan for a TCE-contaminated soil remediation technology using the addition of microbes and not requiring designation of the contaminated site.
Plans include rolling out the technology nationwide as soon as Obayashi has completed the necessary preparations.
The features of the pile stock bioremediation system are as follows.
| 1. | Environment-friendly and safe remediation technology Since remediation is based on microbial degradation alone, there is no use of chemicals that pose a risk of secondary contamination. The safety of the microbes used has been confirmed in a variety of tests, and the absence of any impact on the soil ecology has also been confirmed. The degradation of the pollutant substances also leaves no byproduct residue, and any gas generated from the pollutant during the remediation process is treated by activated carbon adsorption. After remediation, the soil can be reused, for instance by returning it to the original site. |
| 2. | Quick remediation possible Since the technology uses a microbe with a high degrading ability, the remediation period is shorter than with conventional technology. The remediation process consists only of mixing and stirring the contaminated soil, microbes and enriching agent followed by curing. The curing period can also be completed in approximately 24 hours. The system can therefore deal with several hundred cubic meters a day and realizes a substantial shortening of the processing period. |
| 3. | Low-cost remediation method The treatment of the excavated contaminated soil consists only of the mixing and stirring of the microbes and enriching agent, followed by curing, so that remediation costs are greatly reduced. The amount of microbes is adjusted depending on the degree of contamination, and the amount of enriching agent depending on the quality of the soil. For instance, for TCE-contaminated soil contaminated to a level 10 times above the soil environmental standards, the cost of remediation is around 10,000 yen per ton (around 70% the cost of using conventional methods). |
| 4. | Applicable to all soil qualities The soil-enriching agent can be used to create the optimal conditions for microbial degradation in different soil qualities, so that remediation is possible for clay soil and soil with high moisture content, which were formerly difficult to treat with microbes. |
Apart from TCE, the technology can also be applied to contamination with the following chemical substances: |
|
| • | Substances regulated by soil environmental standards: Cis-1,2-dichloroethylene, 1,1-dichloroethylene, benzene, 1,3-dichloropropane |
| • | Other compounds containing these substances: Trans-1,2-dichloroethylene, toluene, xylene, phenol, cresol, etc |
| Item | Description |
| Microbes used | Non-recombinant microbe |
| Janibacter sp. (strain MO7) | |
| Treatment period | Approximately 24 hours for standard contamination |
| Volume treatable per time unit | Depends on number of machines and soil quality, but with one machine, 25-80m3/hour can be treated |
| Treatment cost | Depends on soil volume, concentration and duration of treatment, but around 10,000 yen/ton |
| Applicable concentration | 30 times more than soil environmental standard |
| Environmental impact | Mixture and curing conducted indoors as a basic rule |
| Vaporized contaminant recovered and treated | |
| Additives restricted to microbes and enriching agent | |
| No addition of chemical substances | |
| Applicable soil quality | Applicable to all soil qualities |
| Facilities required | Treatment building |
| Possible in building due for demolition | |
| Area required for treatment | Curing yard required |
| Ideally at least 2,000 squaremeters | |
| Restoration of soil after treatment | Possible |
