Garside Sands improves Thames Water quality

Garside Sands, part of Aggregate Industries, recently supplied over 2,400 tonnes of Slowfil Sand to Thames Water to improve its water quality for customers across Londona and the Thames Valley.

Thames Water purifies its drinking water using the method of slow sand filtering from its five operational Thames Water sites. The sand is submerged in water in a sand-filled container. The water allows the top layer of wet sand to slowly develop a biological ‘film’ made up of living organisms such as algae and bacteria.

Garside Sands successfully trialled the sand last year in conjunction with Western Carbons. The product demonstrated its ability to meet the acute industry standard for size, grading and colour required for the production of safe drinking water.

The top layer of surface biofilm provides the most effective purification as the living organisms essentially ‘eat’ or attach the pathogens in the water, stopping them from flowing down through the sand.

The natural pull of gravity means that as water travels down the underlying sand continues to provide a level of biological treatment, which lessens as the water reaches the bottom most layer of sand.

Clive Martin, commercial manager at Garside Sands, said: “Slow sand filtering was a method adopted back in Victorian-times and, despite the revolution in technology, is still considered one of the most effective forms of water purification today and used widely throughout the world – all while being incredibly cost effective and environmentally friendly.

“If the sand is of high quality, we know that these filters can produce water that has a 90-99% bacterial cell count reduction. As such, we ensured that we spent the right amount of time in developing a sand that would help to both enhance and maintain the quality of water that Thames Water’s slow sand filters can continue to produce for years to come.”

Aggregate Industries supplies silica sand, with quarries in Leighton Buzzard and Levenseat.

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