Low cost sludge pumping at Greenfield

A Watson-Marlow Bredel SP80 hose pump installed at Hyder Utilities' Greenfield Sewage Treatment Works for primary tank desludging in 1992, has to date cost just £2,490 in spares and maintenance.

Based on the current flow rate of 19,000 litres/day, and taking into account initial capital and installation costs, together with power consumption, over a projected service life of thirty years, the cost of pumping works out at under 10 pence per cubic metre of sludge pumped.

The SP80 is fitted with a 3kW fixed-speed drive and is timer controlled, pumping 5% sludge from circular primary tanks. Suction is through 5 metres of 100mm diameter pipe and a further 15 metres of 150mm diameter pipe with a slight lift. Discharge is to a thickener through 100 metres of 100mm diameter pipe with a 5 metre vertical rise. Other 65mm bore Watson-Marlow Bredel pumps at Greenfield STW, transfer sludge from the thickener to sludge screens, and from the screens to the digester.