MULTIBARRIER, A TECHNOLOGY CONCEPT FOR THE IN SITU REMEDIATION OF MIXED GROUNDWATER POLLUTION

摘要

A laboratory study was set-up to develop a multifunctional permeable reactive barrier, designated as multibarrier, treating simulated groundwater contaminated by mixed organic and inorganic pollutants. A multibarrier combines physical-chemical removal processes in a zero valent iron wall, and microbiological removal processes in an aerobic or anaerobic bioreactive zone. The heavy metals Zn and As(V), and the chlorinated ethenes PCE and TCE were efficiently removed in the zero valent iron columns of the various multibarrier systems. The aromatic hydrocarbons benzene, toluene and m-xylene (BTX) were partially removed through sorption in the zero valent iron columns. The main differences between the various multibarrier systems, operated under different terminal electron acceptor conditions, were found in the BTX biodegradation profiles. Almost complete BTX biodegradation was observed in the denitrifying and aerobic multibarrier columns. Of the strictly anaerobic systems, the ferric iron-reducing multibarrier systems were more efficient than the sulfidogenic column systems, especially due to the partial degradation of benzene observed in the former. Overall, the best performing system was a multibarrier operated under denitrifying conditions in a sequential configuration.