- 29 November 2007 -

Older sand filters remove 'earthy' taste

Australian scientists from the school of chemical engineering at the University of Adelaide have discovered that older, biologically active sand filters can remove geosmin and methylisoborneol molecules from water. Although the chemicals are non-toxic, they can give drinking water an 'earthy' taste which can be off-putting to consumers.

The scientists allowed the particles of sand to accumulate a biological film of beneficial bacteria that absorb and break down the biodegradable odour molecules.

They found that sand taken from a 26-year old filter had a well-established biofilm and was able to remove any detectable traces of geosmin and MIB in less than two weeks. Fresh filter sand with no biofilm, in contrast, was essentially ineffective, removing less than two-thirds of the geosmin and MIB even after several months of operation. This meant that in practice, the older the filter, the better the removal of these molecules.

The new findings were set out in the Inderscience publication International Journal of Environment and Waste Management.

www.adelaide.edu.au