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

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 ( https://www.w3.org/1998/Math/MathML" display="inline"> F e ( 0 ) /bio) multibarriers proved to be suitable for the treatment of the tested pollutant mixture. Good results were obtained with https://www.w3.org/1998/Math/MathML" display="inline"> O 2 , N O 3 - , S O 4 2 - , F e 3 + as terminal electron acceptor.