Bioremediation strategy for monoaromatic hydrocarbons in the Borden Aquifer, Canada

摘要

A batch experiment was conducted to develop a strategy for bioremediation of aromatics under strictly anaerobic conditions at Canadian Forces Base Borden, Canada. This aquifer has very limited potential for in situ bioremediation under denitrifying and sulfate-reducing conditions, and methanogenesis has been difficult to establish in natural gradient field experiments with hydrocarbons. Initial electron acceptor pools including nitrate, sulfate and ferric iron were set up in microcosms using Borden aquifer materials. Results showed that indigenous microorganisms could degrade benzene, toluene, ethylbenzene and xylene isomers(BTEX) under limited nitrate combined with excess ferric iron-amended conditions, but not under sulfatereducing conditions. Toluene, ethylbenzene and m/p-xylene were biodegraded well under denitrifying conditions.However, the persistence of benzene indicated that enhancing denitrification alone was insufficient. Both benzene and o-xylene degraded significantly under iron-reducing conditions, but only after denitrification had removed other aromatics. This study suggests that excess ferric iron with limited nitrate is the best strategy for in situ bioremediation of BTEX in the Borden aquifer.