Welsh wastewater plant goes peristaltic

London -- Welsh Water is employing peristaltic pump technology -- two SPX50 hose pumps from Watson-Marlow Bredel -- at its Lavister Waste Water Treatment Works in North Wales. The units are used for the auto-desludging of the primary tanks at the site, which was previously operated by timer-controlled automatic actuated valves.

Engineers at the Lavister facility, which serves a population of 5500, found the valve technology difficult to control and sludge quality was far from consistent, according to Dave Hughes at Welsh Water.

“The timer controlled actuated valves opened fully for the set time period resulting in variable sludge consistency. Either too much water content resulted at the primary sludge holding tank or insufficient desludging resulted in blanket carry over at the primary tanks” explains Hughes.

The watewater company therefore decided to replace the valves with two SPX50 hose pumps, one for each tank – each of which currently produces approximately 7M3 of sludge/day. Mechanical installation was carried out by Smart Liquid Systems, the electrical work by Lloyd Morris Electrical and civil work by E Jones and Son -- all local contractors.

The hose pumps handle 3-5% dry solids content primary sludge at a transfer rate of 2500 litres/hr. Each pump runs at 16rpm and has a discharge pressure of less than 5 bar. The units are also fitted with WIMES Efficiency1 1.5kW cast iron frame motors with fixed speed gearboxes.