AWWA WQTC71613

In Denmark, drinking water production is almost exclusively based on groundwater. By tradition, treatment processes are simple and limited to aeration followed by one- or two-step rapid sand filtration, generally without the use of disinfection. Increasing pesticide concentrations in groundwater resources cause a problem because rapid sand filters normally do not remove pesticides. Authorities and water companies put a strong emphasis on maintaining simple water treatment for economic reasons, and because the treatment should be as sustainable as possible. Expansion of the water works to include activated carbon filtration or advanced oxidation processes in order to remove pesticides is avoided as far as possible. However, if pesticide removal can be achieved by conventional rapid sand filters by modifying the operation, it is of significant practical interest. At a municipal water works in Denmark, the presence of the herbicide Mecoprop (MCCP) has been observed in groundwater wells, but is not detectable in finished produced drinking water. The objective of this study was to investigate where in the treatment line the MCPP removal takes place, and to identify the removal mechanisms. Includes tables, figures.