Engineering and hydrogeological problems associated with in situ treatment

Abstract

Abstract Most organic materials that contaminate soil and the subsurface environment are readily degraded by natural biological processes. To this degree, in situ bioremediation can be thought of as a highly successful purification process. However, some organic molecules are naturally refractory to biodegradation, or other environmental factors induce molecular recalcitrance such as the absence of a proper microbial population or the presence of unsuitable environmental conditions. Examples of recalcitrant groundwater contaminants are soluble components of petroleum hydrocarbons (BTEX) and chlorinated aliphatic hydrocarbons (CAHs). Organic recalcitrance may be changed through introduction of degrading populations of microorganisms or by changing the environmental conditions through introduction of nutrients or other chemicals. The most significant engineering deficiency in in situ bioremediation is the absence of proven methods to introduce such materials into the subsurface environment for efficient mix...