Fundamentals and practices of soil bioremediation

Many kinds of hazardous waste have contaminated soils as the result of diversify of human life styles. Once soil environments have been contaminated by slightly and hazardous organic materials, ranges of its contamination enlarge spatially by the diffusion and penetration, and finally lead to the pollution of groundwater that will be requested for us the most difficult remediations techniques to put into practice. It is very important, therefore, to decompose these hazardous materials in short periods while they remain in soil ecosystem. Soil microorganisms playing a major part in the decomposition of these materials, we have to arrange their living circumstances in soil ecosystem. However, natural soil environment for microorganisms provide not always a suitable condition to produce the biochemical reaction, for example soil physical structure are too fragile when soil get wet and also they have not a uniform pore but a wide variation in size. For the selection of suitable microhabitates, several kinds of materials coated with nutrients were examined by burying in soil. The material with a uniform and suitable size for the fixation of a soil microorganism gave a typical growth curve of a single cell multiplication when it was dug up from the soil after two months. On the other hand, the materials with large and wide variation size did not give a typical growth curve of a single cell multiplication. This fact shows the possibility of selection of specific kinds of microorganisms from soil and promotion of the biochemical reaction through their vigorous fixation in microhabitates. Some kinds of charcoals and burned diatomaceous earth will be estimated as low cost and suitable materials for microhabitates. In this paper, a soil bioremediation technique for the oil-contaminated soil will be introduced mainly, and also the execution of improved river water quality using microhabitates technique will be shown partly.