Presence and fate of manganese substances in drinking water supply systems

Abstract

A wide range of material sources may potentially contribute to contaminant loads in the potable water. The ability of water supply systems to act as emission control barriers for tap water micropollutants, thereby providing environmental benefits in addition to potable water savings, have not been fully explored. This paper investigates the sources, presence and potential fate of a selection of manganese micropollutants in laboratory scaled water supply systems. All of the investigated compounds are listed under the European Council Directive 98/83/EC on the quality of water intended for human consumption (1998) and World Health Organization Guidelines for Drinking-water Quality (2004). Significant water quality changes are identified. Hydro-chemical modelling indicates that the removal of manganese substances during water treatment is likely to be predominant due to the EC Directive manganese concentration requirement, with only minor contributions to the water supply network. Manganese compounds are resistant to biodegradation and the majority of conventional groundwater treatment plants periodically supply water with manganese residual to the potable water distribution system. Water treatment is unlikely to act as a comprehensive barrier for emission of manganese compounds. Hence, it is important to ensure that other manganese source control options (e. g. pipeline materials, manganese substance emission, and groundwater source control) for potable water supply continue to be pursued in order that emissions of manganese compounds from these sources are effectively reduced and / or phased out as required under the demands of the European Council Directive 98/83/EC on the quality of water intended for human consumption.