A 10.5 million-gallons-per-day (MGD) continuous microfiltration-submerged (CMF-S) system from USFilter Memcor® Products is ensuring a safe drinking water supply for residents in the West London, England area.
Fully operational in February 2003, the system is installed at Chertsey Water Treatment Works (WTW), operated by Three Valleys Water. CMF-S technology, combined with downstream ozonation and carbon filtration, acts as a barrier to bacteria and protozoa, including cryptosporidium, in the ground water wells at the WTW. The system is also designed to treat water from the River Thames for short periods, should groundwater sources be unavailable.
Three Valleys Water awarded the contract to USFilter's sister company, Veolia Water Partnership, and Black & Veatch Contracting Limited to design and supply the membrane filtration system following several months of successful CMF-S system pilot testing.
Says Dawn Guendert, Membrane Product Manager at USFilter, "A pilot study was conducted on two water sources, Abbeymead well water and River Thames, which are susceptible to cryptosporidium contamination. Testing of the Memcor CMF-S system demonstrated the capability of the membranes to treat both the groundwater and surface water sources. The testing on the Abbeymead well water included oxidization upstream of the CMF-S to precipitate iron, allowing the reduction of iron as well as turbidity and suspended solids. Subsequent pilot testing on the River Thames, where turbidity ranges between 20 and 50 NTU, with spikes up to 100 NTU, showed that the CMF-S was able to consistently produce product water with turbidities less than 0.2 NTU, and provide an effective physical barrier to cryptosporidium."
The CMF-S system at Chertsey WTW consists of six membrane filtration cells, with each cell containing 192 PVDF membrane modules and "rack inserts" to increase system recovery and minimize waste disposal. Five of the six cells will be used to filter the incoming water, with the sixth cell operating as a backup while one of the other cells is being backwashed or cleaned. The system's product water is sent at a constant flow to downstream ozone contact tanks, and then to the carbon filters.
A programmable logic controller (PLC) allows the operator to interface easily with each cell by using the graphical user interface. To ensure that the microfiltration membrane is providing an effective barrier between feed water and product water, the CMF-S system includes a built-in, automated, pressure decay test, which is easy for the plant operator to monitor.
Three Valleys Water, a Veolia Water company, is the UKs largest water-only supply company, serving three million customers with more than 200 million gallons of high-quality water every day in an area north and west of London.
USFilter Memcor Products provides flexible, state-of-the-art integrated microfiltration and reverse osmosis membrane solutions for treating groundwater, surface water, seawater, industrial process water and water for reuse. A manufacturer of municipal and industrial microfiltration systems, USFilter Memcor Products continues to develop new membrane polymers, module configurations and system designs for today and into the future.