Influence of various degradation conditions on the properties of gas-generating soils in the process of their decontamination

Abstract

The properties of gas-generating soils (GGS) in the process of biofermentation under anaerobic and aerobic conditions are studied. The degradation of organic matter (OM) in a soil under natural occurrence conditions (without free access of air oxygen) at temperatures from 10 to 12°C is demonstrated to proceed at a specific reaction rate of k = 0.096 year⁻¹. The main phase of gas generation (biogas formation) is shown to take 15 years, with the content of methane in the biogas being 60−80 vol %. It has been established that, under the conditions of forced aeration of the GGS array, the specific reaction rate of OM degradation increases 10-fold, to 0.9673 year⁻¹, with a nearly complete decomposition of OM taking 1.5−2.0 years. A prerequisite for achieving of the predicted result is the maintenance of the environment humidity at a level not lower than 50%. Application of an alternative method, a thermal treatment of GGS increases the degree of OM decomposition to 59% within 4 h at 200°C and to 75% within 2 h at 300°C. In this case, residual organic substances are carbonized in the course of thermal treatment, transforming into a material resistant to microbiological decomposition. In fact, after heating at 200−300°C, GGS becomes inert from the gas-geochemical point of view.