08 Nov, 2016

The United Kingdom’s Royal Agricultural University (RAU) has joined forces with a regional water company to investigate ways to reduce the occurrence of metaldehyde in drinking water.

Thames Water, the water company responsible for supplying London with its drinking water, has awarded RAU postgraduate student Tom Edwards a Master of Science by Research, following Tom’s investigation into the use of ‘swales’ as a potential mechanism to reduce metaldehyde concentrations in watercourses.

Although the Royal Agricultural University is situated some 100 miles west of London, it is within the catchment area of the River Thames. Metaldehyde is difficult to remove from water using current treatment processes, hence the interest shown by Thames Water in Tom’s research.

Swales are designed to collect field run-off in shallow ditches, providing a ‘natural’ water treatment through interaction with soil, bacteria and vegetation. Previous studies have shown swales’ effectiveness in reducing other pollutants such as heavy metals and nutrients, but they have remained unproven for plant protection products.

The RAU has established two experimental swale sites, where water is taken from an existing stream before travelling the length of the swale. Here it makes contact with soil and root systems which, it is hoped, will effect a reduction in metaldehyde levels. Water flowing out of the swale returns to the watercourse, heading downstream where it will be extracted by Thames Water for further treatment to produce drinking water.