MODELLING THE EFFECTS OF LACTATE INJECTION TO PROMOTE IN SITU ANAEROBIC BIOREMEDIATION OF A CAHs CONTAMINATED AQUIFER

In this work the possibility of treating a chlorinated solvents (CAHs) contaminated plume by injecting into the aquifer an exogenous electron donor to promote biological reductive dechlorination (RD) by stimulating the methabolic activity of native microrganisms at a former industrial site is considered. The effects of the addition of lactate as a possible amendant have been evaluated by developing a specific reactive module, to be coupled to the transport one, capable of fully describing the complete set of biochemical processes occurring in a CAHs contaminated groundwater when a fermentable substrate is added. The model allows for both the selection of the optimal configuration of the amendant delivery system and for the analysis of the distribution and eventually accumulation of undesired metabolic by-products resulting from either fermentation or incomplete RD. First outcomes indicate that cleanup targets can only be achieved if source longevity is reduced and might suggest to shift the proposed remediation approach to the treatment of zones were chlorinated solvents' release originates, that is to say either the original source or any downgradient area where such contaminants might have accumulated in the form of residual DNAPLs.