Development of physical-biological filters for groundwater remediation of tetrachlorethen and naphthalene

Still, groundwater clean-up is a day-to-day business mostly dedicated to former soil and groundwater contaminations by anthropogenic compounds like chlorinated aliphatic hydrocarbons (CHC) and polycyclic aromatic hydrocarbons (PAH). Such volatile organic compounds account for a large number of contaminated sites in Europe, as well as Austria. State of the art remediation methods such as pump and treat often require years of operation, mainly due to the low water solubility of the contaminants and low groundwater flow velocity limiting the travel time to the adjacent extraction well. Hereafter, we present the current standing of the project „CHARBAK”, which was funded by the Kommunalkredit Public Consulting (KPC, Vienna, Austria) and deals with alternative filter designs for ex-situ groundwater remediation. The presented project aims to develop a physical/biological filter for pump and treat (ex-situ) groundwater remediation of chlorinated ethenes (CHC) and naphthalene (PAH). For such applications filters are preferentially filled with activated carbon, which has to be replace after its sorption capacity has been exhausted. We envisioned an alternative filter design by combining environmentally friendly biochar with contaminant-degrading microbial consortia. While groundwater percolates through the biochar filter, contaminants are adsorbed and microbes that colonize the biochar surface can successively degrade the contaminants. Such processes should provoke an increase in the filter life time as well as reduce investment and maintenance cost.
Major project tasks encompass the production and characterization of biochars, evaluating the interaction of biochars and microbial consortia in batch-experiments and column experiments to monitor contaminant adsorption and microbial degradation in a closed-loop flow-through filter experiment to simulate real-time conditions.