The Environmental Land of the Earth: The Trajectory of Technological Innovation in Oil Contaminated Soil, 2000s

The Environmental Land of the Earth: The Trajectory of Technological Innovation in Oil Contaminated Soil, 2000s

In Japan in the 2000s, redevelopment of former factory and gas station sites was becoming increasingly popular, while the enforcement of the Soil Contamination Countermeasures Law made environmental risk and urban development inseparable issues. Oil-contaminated soil was always a barrier that stood in the way of redevelopment, and there was an urgent need to establish an efficient and economical treatment method. The conventional treatment method is to remove the excavated contaminated soil from the site and purify it by volatilizing hydrocarbons through low-temperature heating at 200 to 300 degrees Celsius. Kajima Road and Taisei Corporation have built large-scale treatment facilities and established a system that can handle projects in the tens of thousands of tons. However, this method was costly and time-consuming, and its limitations were pointed out on site.

On the other hand, advances in bioremediation, which utilizes microbial degradation, have attracted attention. The agitation-type on-site equipment developed by Ritsumeikan University and Nippon Engineering has made it possible to shorten the treatment time from one to three months, compared to the six months to one year required in the past. Efficiency was dramatically improved by mixing decomposing bacteria and nutrients uniformly into the contaminated soil and maintaining optimal conditions through automatic control. This has made it possible to respond more realistically to medium-scale projects that were previously avoided due to cost and time constraints.

During the same period, on-site treatment, in which air is pumped in and volatilized components are adsorbed by activated carbon, and methods combining groundwater pumping and air sparging became popular as measures for volatile organic compound contamination. Technology for oil contamination was applied to find ways to deal with combined contamination. In addition, stabilization technology was introduced for soil containing heavy metals, in which cementitious solidifiers were mixed to prevent the elution of toxic substances, and various treatment methods were developed according to the type of contamination. In addition to pumping, biostimulation, in which oxygen and nutrients are injected to increase microbial activity, was put to practical use to deal with groundwater contamination, shedding light on invisible underground contamination.

Internationally, trends such as the remediation of contaminated sites under the Superfund law in the U.S. and the REACH regulation in Europe were influential. Japan was also becoming increasingly aware that environmental risks could affect asset values in the international investment market, and financial institutions were beginning to evaluate remediation technologies as part of risk management. Remediation technology for oil-contaminated soil became more than just an environmental protection measure; it also involved real estate and urban policy, and became an important factor in determining the speed of urban renewal.

Thus, the technological innovations of the 2000s were nurtured as a crystallization of wisdom for balancing environmental protection and economic development, and formed an indispensable foundation for future urban development.