Veolia and Affinity Water work closely to find solution

ActifloCarb® removes Metaldehyde

Veolia Water Solutions & Technologies has been working closely with Affinity Water to develop a process to remove metaldehyde from drinking water. Metaldehyde, a pesticide used for slug control, is being found in many UK water sources, with a potential risk of non compliance with Water Quality Regulations, which set a maximum concentration of 0.1µg/l for pesticides.

To deal with this issue, Affinity Water has been looking at removal technologies. In December 2012 Veolia installed a pilot scale ActifloCarb® system at Affinity Water’s North Mymms treatment works and, in close cooperation with Affinity Water, operated it for three months during which it consistently achieved metaldehyde residuals of less than 0.02µg/l.

Based on the highly successful Actiflo® high rate, sand-ballasted sludge clarifier, ActifloCarb® adds powdered activated carbon (PAC) to adsorb pesticides. PAC, coagulant and flocculant chemicals are added along with fine sand for weighting the resulting floc which is removed in a lamella clarifier. Most of the PAC is recirculated to minimise operating costs, and the sand is recovered in a hydrocyclone.

“We needed to find a technology to remove metaldehyde,” says Affinity Water’s Process Engineering Science Manager, Richard Lake. “This collaboration with Veolia has been a great success and demonstrated that ActifloCarb® is effective treatment against this pesticide.”