Study on the Model of Organic Contaminant Transportation and Biodegradation in Unsaturated Soil

In order to obtain the regularities of organic contaminant distribution in soil environment, the model for describing the interaction, transportation and transformation of organic contaminant, electron acceptor and bacteria was established based the soil water dynamics, the theory of solute transportation and the principle of micro-biological degradation by using double Monod micro-biological degradation. The numerical simulation analysis was performed taking benzene for example. The simulation indicates that with the increasing of contaminant concentration and the reducing of dissolved oxygen concentration, the bacterium concentration increases first and then reduces; the bacteria chiefly aggregate in the zone that both the nutrient concentration and oxygen concentration are higher, and the aggregation area moves down with the time increasing; the contaminant concentration, the dissolved oxygen concentration and the bacterium concentration have high relevance with each other.