Thames Water is the UK’s largest water and sewage treatment company, providing wastewater services to 15 million customers through 305 sewage treatment works. SEEPEX progressive cavity (PC) pumps have delivered process improvements at their Sewage Treatment Works at Reading by reducing onward sludge transport costs, as well as reducing operating costs associated with piston pumps.
Thames Water replaced the piston pumps, which transferred de-watered digested sludge from the energy generation plant to storage silos, with SEEPEX progressive cavity pumps. Thames engineers identified that if they increased the ds content of the dewatered sludge from 22% to 25% this would deliver a large saving in disposal costs. However they needed reliable pumps to transfer the dewatered sludge over 80metres, with a static head of 30m, without increasing system costs. The piston pumps on the process were identified as a limitation due to maintenance requirements and the high pressures generated. Additionally they used 31KW of power – all adding up to a high cost of ownership for Thames Water.
In contrast SEEPEX supplied pumps to transfer the higher ds% sludge with a lower energy consumption and at a lower pressure rating, operating as the principle project manager, and working with Thames Water approved contractors to deliver a turnkey installation. The SEEPEX open hopper progressive cavity pumps deliver the higher ds% sludge with 50% reduced power consumption (15KW) and up to 75% reduced discharge pressure, enabling de-rating of pipework and valves to suit.
The pressure reduction has been achieved in 2 ways
- Progressive cavity pumps have a low pulsation action, which generates a lower in-pipe pressure than piston pumps
- A boundary layer injection system reduces friction losses in the 80m length of pipework, using a polymer injection pump linked to discharge pressure, controlled by a SEEPEX control system.
The pumps have been installed for over 12 months, requiring no maintenance interventions in this time. The SEEPEX system has delivered a hat-trick of cost reductions: lower sludge disposal costs, lower energy use and reduced maintenance costs.