Comparison of different MULTIBARRIER concepts designed for treatment of groundwater containing mixed pollutants

摘要

A study was set up to develop and evaluate the possibilities of multibarriers for the remediation of groundwater contaminated with a mixed pollution. A multibarrier is a multifunctional permeable reactive barrier in which biological and physicochemical pollutant removal processes can be combined. Different combinations of biodegradation, reductive dehalogenation using zerovalent iron and sorption were considered to treat a mixed pollution consisting of heavy metals (As, Zn), aromatics (Benzene, toluene, m-xylene) and volatile chlorinated compounds (PCE, TCE). Biodegradation of BTEX in batch-sytems was found to be negatively influenced by the presence of zero-valent iron and other pollutants. Starting from the same aquifer mixture, addition of different electron-acceptors selected for a different BTEX-degrading microbial population as determined by PCR-DGGE. Based on column experiments which simulated different multibarrier concepts, sequential as well as mixed (Fe(0)/bio) multibarriers proved to be suitable for the treatment of the tested pollutant mixture. Good results were obtained with O_2, NO_2~-, SO_4~(2-), Fe~(3+) as terminal electron acceptor.