Articles & Case Studies

Linatex supply new sand filter bed treatment plant to Bournemouth & West Hampshire Water

Posted: Thursday 25th March 2010

As one of the leading performers in the UK Water industry Bournemouth & West Hampshire Water (BWHW) provide clean drinking water to around half a million people in an area from Poole to Beaulieu and from Bournemouth to Salisbury, an area of over 1000 square kilometres. They have an excellent record for water quality, and supply on average about 150 million litres of drinking water every day, through nearly 3000 kilometres of water mains.

With a new pumping station to be installed at their Knapp Mill site in Christchurch the Company contacted Centristic Ltd of Newton Abbott to facilitate the re-siting of the existing Linatex sand filter bed treatment plant. A comprehensive review revealed that elements of the present Linatex Sand Plant were too small for the feed requirements.

Linatex has a long history in Sand Plant Design and have enjoyed a long standing relationship over 25 years with BWHW. As a result, they were tasked to supply a new 25tph sand processing system, with Centristic acting as main contractor on the plant build.

Maintenance of the sand filter beds at Knapp Mill is performed on a continuous cycle

with 30mm being skimmed off the beds approximately every four months. To maintain effective operation the filter beds must retain a minimum of 300mm of sand above the carbon, therefore after skimming the Knapp Mill team ensure that 100mm of clean sand is replaced on the filter bed. This continual process is effectively a recycling operation as new sand is only introduced approximately every ten years.

As it is essential that the sand quality is maintained in this operation the skimmed sand requires scrubbing to release any impurities (silts, clays, weeds) before the Linatex sand plant effectively washes and dewaters the material.

The material, being essentially wet filter bed sand (largest particle size 5mm) is fed by wheel loader into a hopper which feeds onto a 15 metre long inclined conveyor which delivers the material into a 1.2 metre diameter x 3.0 metres long trommel (sand scrubber barrel) which is lined with Linatex rubber and lifters. Sand and water discharging from this barrel is then flumed down a Linatex lined chute to the centre of a 2.1 metre diameter Linatex feed regulating sump with any overflow from the sump gravitating to waste.

From the base of the sump a 100/100mm bore Linatex lined centrifugal pump draws the slurry and feeds via 100mm bore pipework to a Linatex lined HK 100 extended sand separator with the overflow from the separator returning to the vicinity of the feed sump for balancing the system or disposal to waste.

The Linatex HK 100 separator is constructed with mild steel and is Linatex lined in all wear areas. Fitted with extended feed box, discharge regulator and pressure flange assembly the separator incorporates two pressure gauges to measure inlet pressure and vacuum that are key to performance of the unit to maintain operational efficiency and maximise sand recovery.

The sand separator which is mounted in a supporting tower incorporates 3 discharge chutes providing approximately 2,000 tonnes stockpile capacity.

With the need to retain as much fine material as possible (95% above 50 micron) the Linatex extended separator ensures that the quality is achieved, proving itself to be a cost effective method of providing clean sand to a very high standard.

Since supplying a system for the BWHW Alderney water treatment works some 19 years ago Linatex have worked closely with the client consistently providing the technology and expertise in terms of sand processing plant.

Tony Primmer – Production Manager, commented, “It is very pleasing to continue our long term relationship with Linatex. They have always provided us with first class sand washing plants and together with the excellent after sales back up, we look forward to working with Linatex for many more years to come.”

Tel: 01252 743000
Fax: 01252 743030

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