Separating suspended solids from liquids before discharging to sewer or water course is a headache that construction companies have had to endure for a considerable period of time. Aggravating the problem further is when materials won’t settle quickly. To overcome this obstacle Monmouth-based Siltbuster has standardised on innovative 500 and 600 series peristaltic pump technology from Watson-Marlow Bredel, ensuring that construction projects can continue without delay whilst meeting very strict environmental standards.
Established in 2000, Siltbuster has grown quickly to become the UK’s leading designer and manufacturer of mobile silt management equipment. Today the company has in excess of 60 silt pollution prevention projects ongoing at any one time, as far afield as the Orkney Isles and New South Wales, Australia.
The company’s core product, Siltbuster, is a range of liquid / solid separation devices designed for temporary use on construction sites to remove suspended solids and oil from water pumped from holes, excavations or surface run-off. The Siltbuster units have been developed to meet the increasing need to improve the environmental protection of water courses, groundwater and marine environments, and the process is now considered best practice for the management of dirty water pumped from construction sites.
However, it is not all plain sailing, as Siltbuster’s managing director Dr Richard Coulton explains: “Unfortunately we are never entirely sure what we are treating until we see it. On some jobs fine particles settle extremely slowly or not at all – so we have to help them settle faster via chemical conditioning techniques such as flocculation, coagulation or pH adjustment. We use Watson-Marlow Bredel 500 and 600 series peristaltic pumps to help facilitate this process.”
Siltbuster previously used diaphragm pumps for chemical addition, but grit blocking the valves was a continual problem.
“When this happened we would have numerous construction workers sitting around playing cards, as well as idle plant,” says Dr Coulton. “Downtime in the construction industry is costly and we couldn’t afford any more pump failures, so we looked for an alternative pump type. The Watson-Marlow Bredel pumps appeared robust, reliable and importantly, foolproof. As mobile units, the Siltbuster systems need to be maintained on-site by construction workers who are perhaps not familiar with water treatment
In Watson-Marlow Bredel peristaltic pumps, nothing but the tube touches the fluid, eliminating the risk of the pump contaminating the fluid or the fluid contaminating the pump. Fluid is drawn into the pumphead and trapped between the rollers and the track. As the next roller moves forward, the pocket of fluid is expelled and more is drawn in to the tube by the vacuum that is created. The complete closure of the tube gives the pump its positive displacement action, preventing backflow and eliminating the need for check-valves when the pump is not running.
The pumps, which often run 24/7, are ideal for slurries, viscous, shear-sensitive and aggressive fluids, and are easy to install, simple to operate and inexpensive to maintain.
“We have now standardised on Watson-Marlow Bredel pumps,” says Dr Coulton. “I think we have bought around 30 units to date (the pumps are integrated by Siltbuster into its dosing and pH systems) and have had very few problems.”
The Siltbuster process, in contrast to conventional settlement tanks, stills the incoming water / solids mix and routes it upwards between a set of inclined plates for separation. Fine particles settle on to the plates and slide down to the base for collection, while treated water flows to an outlet weir after passing below a scum board to retain any floating material. The inclined plates dramatically increase the effective settling area of the unit, resulting in a smaller space requirement on-site and a process that unlike lagoons, is unaffected by wind disturbance.