Pesticide removal from drinking water sources by adsorption: a review

Pesticides are an important part of crop production worldwide, however their use poses a threat to potable water sources. Seasonal use of pesticides can cause increased concentrations to be detected at potable water abstraction sites as a shock load which can be difficult for conventional treatment processes to deal with. Concentrations of pesticides above 0.1 µg/L in drinking water contravene the regulations as laid out in the Drinking Water Directive and cause significant reputational and financial impact to water companies. This review considers the relationships between the pesticides that have caused compliance failures and their physico-chemical properties, and factors such as weather and rainfall. It was found that over 50% of the pesticide compliance failures in England and Wales were caused by the molluscicide metaldehyde and that the majority of the problematic pesticides are considered to be polar and mobile. The review looks in further detail at five different pesticides with differing physico-chemical properties known to have caused compliance failures and to be of particular concern for water companies. In addition adsorption media which could be utilised in agricultural catchments were investigated to understand whether they could be applied to prevent the onward contamination of potable water sources.