Natural Attenuation of Priority and Emerging Contaminants During River Bank Filtration and Artificial Recharge

The fate of various emerging contaminants as well as priority pollutants from the European Union Water Framework directive was examined along a complex combination of natural and engineered processes used to produce drinking water downstream of a major metropolitan area. The sampling points examined comprised Seine river water downstream of the Paris area, water from a primary well after bank filtration, water from a secondary well influenced by an artificial recharge process and water from the mixture of secondary wells after drinking water treatment. More than 80 organic contaminants including drugs, polycyclic aromatic hydrocarbons, pesticides, oestrogenic hormones, polybrominated diphenyl ethers, chlorophenols, nonylphenols, were monitored during five campaigns. River bank filtration and to a lesser extent artificial recharge clearly decreased the variety of contaminants, in particular a variety of drugs detected in the river. On the other hand riverbank filtration was found to increase nonylphenols by anaerobic degradation of nonylphenolpolyethoxylate precursors. Traces of aspirin, nonylphenols and stimulants were occasionally detected in the finished drinking water above 0.1 μg/L.