Veolia and Affinity Water work solve Metaldehyde water problem 21 October 2013

Veolia Water Solutions & Technologies and Affinity Water have together developed a process to remove metaldehyde from drinking water.

The pesticide, which is used for slug control, is being found in many UK water sources, leading to a potential risk of non compliance with water quality regulations, which set a maximum concentration of 0.1µg/l for pesticides.

In December 2012, Veolia installed a pilot scale ActifloCarb system at Affinity Water's North Mymms treatment works and operated it for three months. The result, according to Affinity Water's process engineering science manager Richard Lake, was metaldehyde residuals of less than 0.02µg/l.

Based on the Actiflo high-rate, sand-ballasted sludge clarifier, ActifloCarb effectively adds PAC (powdered activated carbon) to adsorb pesticides.

Lake explains that 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 then recirculated to minimise operating costs, and the sand is recovered in a hydrocyclone.

"We needed to find a technology to remove metaldehyde," says Lake.

"This collaboration with Veolia has been a great success and demonstrated that ActifloCarb is effective treatment against this pesticide."

Brian Tinham

Related Companies
Affinity
Veolia Water Technologies

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