Presence and fate of manganese substances in potable water treatment and supply systems

Abstract

A wide range of material sources may potentially contribute to contaminant loads in potable water. The ability of water supply systems to act as emission control barriers for tap-water micro pollutants, 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. A wide range of potential treatment trains are available for water treatment and reuse but treatment efficiency data for manganese substances is very limited. Hydro- chemical mod¬eling indicates that manganese substances removal during water treatment is likely to be predominantly due to EC Directive manganese concentration requirement, with only minor contributions to the water supply network. Manganese compounds are resistant to biodegradation and as 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 manganese compounds emission barrier. Hence, it is important to ensure that other manganese sources control options (e.g. pipelines materials, manganese substance emission, and groundwater sources controls) for potable water supply continue to be pursued, in order that manganese compounds emissions 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.