Articles & Case Studies


Posted: Tuesday 20th April 2010

As part of £7.0 million investment by South East Water to improve water quality from groundwater sources at Trossley and Borough Green in Kent, three large degassing / aeration towers and flocculation tanks were designed, built and installed by Forbes on behalf of the main contractors, Enpure. The treatment works is designed to handle up to 1000 cubic metres of water per hour.

Each tower is specifically designed by Forbes to remove dissolved carbon dioxide to increase the pH. The towers are 2.9 metres diameter with a height of 6.2 metres manufactured to meet the stringent requirements of the DWI Regulation 31 (Water Quality). The towers being elevated to an overall height of 13m above ground level to allow gravity discharge into the flocculation tanks

All the tower internals are in polypropylene including the Pall Ring Packing which was supplied by the Pall Ring Company. Included in the package are the aeration fans – complete with duty standby units; all the ducting from the fans into the towers, the large 700mm diameter outlet pipework in polypropylene reinforced with GRP, complete with manifolds from each tower to feed the degassed water into the flocculation tanks.

Enpure’s design which incorporated gravity feed to the flocculation process gives significant cost savings and this combined with the very low power requirement for the fans, helps to keep the overall running costs to a minimum.

Forbes installed the three towers complete with all tower internals; fans and ducting; the large diameter manifold from the tower outlets and the three flocculation tanks. Forbes, now in their 50th year, is the largest UK manufacturer of custom designed tanks and columns in the UK and is major supplier to the Water Utilities. They have the capability of both process and mechanical design in a large range of products in plastics materials and glassfibre reinforced composites. One piece structures in composite plastic materials up to 10 tonnes in weight can now be easily handled in their recently commissioned custom built manufacturing facilities in Kelso, in the Scottish Borders. +44 (0) 1366 389615

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