Toshiro Hata

Pumping-rate control for contaminated groundwater with VOCs by using fuzzy inference model

In this paper, a new method is proposed for the remediation of contaminated groundwater. The method is based on fuzzy inference and risk evaluation. The effectiveness of the presented method is assessed in numerical simulations. The main results of the study are as follows: 1) A pump-and-treat control algorithm was proposed by using the fuzzy inference and the human health risk calculation model, 2) It was found that applying the proposed algorithm was likely to reduce the pumped quantity, and 3) It was found that the proposed model can be used to notify residents of the human health risk; the model is based on the ASTM RBCA model for residents. A new fuzzy control system for contaminated groundwater can be used as a useful model for characterising the effects of contaminants on human health and providing helpful information on the human risk assessment of the contaminated groundwater site.

POSSIBILITY FOR SOLIDIFICATION OF PEATY SOIL BY USING MICROBES

Peaty soil is widely distributed in Hokkaido. Untreated, it is too soft for use as a civil engineering material. Soil solidification improvement technologies that harness the metabolism of microbes in soil have recently been gaining attention. Such research and development has proceeded within and beyond Japan. The researchers investigated a technology for peat solidification that harnesses the ability of microbes inhabiting the soil of construction sites to precipitate calcium carbonate, and consideration was given to solidifying peaty soil by harnessing the ability of those microbes. Focusing on the urease activity of microbes, which has an influence on solidification of peaty soil, a soil solidification test, in which the metabolism of microbes was utilized, and an experiment, in which the degree of solidification of peaty soil was tested, were done by using peaty soil samples from Hokkaido. The two experiments found the following. 1) Microbes that have urease activity inhabit the peaty soil of Hokkaido. 2) It is possible to solidify peaty soil by enhancing the urease activity of these microbes. 3) It is possible to evaluate the degree of urease activity in peaty soil by measuring its electric conductivity.

NEW MICROBIAL-FUNCTION-BASED REINFORCEMENT METHOD FOR EMBANKMENT `

In recent years, erosion control has been increasingly implemented for land embankments of public roadways (e.g., express highways). In the field of geo-environmental engineering, it is important to develop an easy-to-use maintenance method for such embankments based on a natural process. This study aims to develop an eco-friendly and inexpensive maintenance method for embankment management. In this paper, the general concept of the newly proposed method is presented based on the results of laboratory tests and numerical simulations. The most important advantage of this method is the enhancement of urease activity in the in-situ microorganism community. Laboratory tests showed that microbial carbonate precipitation (MCP)-treated sand can increase the liquefaction strength. The numerical simulation results show that an MCP-treated embankment surface shows a rigid frame structure. These results show that the proposed method is suitable for use as an embankment maintenance method.