Enhanced Natural Attenuation (ENA) of heterocyclic aromatic hydrocarbons< Back

Heterocyclic hydrocarbons are toxic and frequently also cancerogenic hydrocarbons that are found in the groundwater at tar-oil polluted sites. This class of pollutants is not analysed in the standard analytical protocols. However, the few available field studies indicate that the heterocyclic hydrocarbons are characterized by slow biodegradation - in particular under anaerobic conditions - and a high mobility in the groundwater plumes. Since the natural biodegradation and retardation processes are not very efficient, additional measures are studied to eliminate these hazardous pollutants. It is the objective of this project to develop techniques to stimulate the aerobic biodegradation processes.

At the Water Technology Center, the microbial degradation of heterocyclic hydrocarbons is studied under the anaerobic redox conditions occuring in most plumes and after addition of oxygen. Biodegradation is examined with well defined mixtures of representative heterocyclic compounds and in microcosms sampled downgradient of tar-oil polluted sites. Biodegradability tests are performed in the presence of the most important electron acceptors (oxygen, nitrate, Fe(III), sulfate, carbonate). Furthermore, the effects of other compounds, e.g. pollutants such as PAH, on the degradation of the NSO-heterocycles is investigated. The techniques developed in the project will be tested in the VEGAS large-scale experimental facility. Afterwards, field demonstration and further improvement under site conditions is intended.