The impact of microbial processes on the efficiency of reactive walls

Abandoned industrial sites normally contain hazardous contaminants, leading to an expected impact on the downstream water quality. At most existing sites complete remediation independent from technology is impossible. The success of in situ remediation is normally poor; the costs are high and a long tailing effect can be observed. For this reason, recently developed methods for downstream groundwater remediation (reactive systems) are known to be very economical and might help to prevent further contaminant distribution in the environment. The improvement of this technology is possible using biodegradation processes, which result from the simultaneous adsorption and biotransformation of volatile chlorinated hydrocarbons in the presence of activated carbon. How to take advantage of biodegradation to extend the operation time of reactive systems in the subsurface is discussed here. However, microbial activities can also cause undesired effects, e.g. clogging by biomass formation or iron precipitation. Both the beneficial and undesired microbial contributions in the field of reactive systems must be considered.