For bioremediation projects at sites contaminated with chlorinated ethenes, inoculation of soil with specific microorganisms is not necessary if the soil already contains the essential dechlorinating organisms. However, sandy soils that are not strongly reduced seem to lack the necessary bacteria for a quick and effective bioremediation. In these cases bioaugmentation of the soil can be a good solution. In 1999, Bioclear started the first full-scale bioaugmentation project at a tetrachloroethylene (PCE)-contaminated site in Hoogeveen, the Netherlands. Using Dutch funding for research on in situ bioremediation, a new concept for bioaugmentation was developed, called the Totaal Concept Evenblij (TCE). With this concept, an anaerobic bioreactor containing biomass (among others Dehalococcoides ethenogenes) capable of dechlorinating PCE into ethylene is used to inoculate the contaminated soil. PCE-contaminated groundwater is used as feed for the reactor, and effluent from the system is infiltrated in the soil as an inoculum. Since 1999, full-scale remediations at seven sites in the Netherlands and Denmark have been performed with this technology, and the number of sites will increase.
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