Garside Sands, part of leading construction materials supplier Aggregate Industries, has supplied more than 2,400 tonnes of its pioneering Slowfil Sand to Thames Water, as part of an ongoing programme to improve its water quality for customers across London and the Thames Valley.
Garside Sands supplied the sand following a successful trial last year in conjunction with Western Carbons, anthracite filter media specialist.
The product meets the acute industry standard for size, grading and colour required for the production of safe drinking water. The process of slow sand filtering takes place in a sand-filled container, in which the sand is initially submerged in water.
This water allows the top layer of wet sand to gradually develop a biological ??film?? made up of living organisms such as algae and bacteria. Once this has occurred the water filtration process can begin. The surface biofilm (top layer) is the layer that provides the most effective purification as the living organisms essentially ??eat?? or attach to pathogens in the water, effectively stopping them from flowing down through the sand.
As water travels down, due to the natural pull of gravity, the underlying sand continues to provide a level of biological treatment, which lessens as the water reaches the bottom most layer of sand.
