Cross filters restore continuous operation to remote water treatment plant

Cross automatic water filters have helped a water company improve filtration at a remote, unmanned water treatment plant. The plant treats shallow well spring water collected from the surrounding fells at a rate of up to 1000m3/day to supply nearby communities and towns.Membrane filtration was introduced at the plant to protect against the threat of cryptosporidium. Fluctuating raw water quality placed a heavy work-load on the inlet strainers fitted to the membranes, leading to excessive membrane backwashing and supply interruptions necessitating excessive manual attendance at the site to en-sure continuity of supply.

To the customer a vital requirement was to secure a dramatic improvement in inlet filtration performance to protect the membranes within the confines of the existing building. Filtration specialists John Morfield were called in to asses the problems and to provide a cost effect solution They designed a compact system based on the use of Cross zero-gravity filtration backwash technology and 3MCuno cartridge filtration. Cross Phoenix filters have been fitted be-hind the original strainers to permanently filter out all particles that are above 50 microns.

Cross zero-gravity filter coils backwash automatically to a completely clean condition on a preset differential pressure signal with a time lapse back-up. The Cross Phoenix filter units each comprise six coils which are individually and sequentially backwashed with no interruption to flow through the filter. Backwashing is performed without any interruption to the flow and therefore without any impact on the operation of the membrane systems. The filter assembly fitted with 3mCuno cartridges then acts as a guard filter to remove any residual smaller solids before the water reaches the membranes.

This system was successful in preventing premature fouling of the membranes and eliminated emergency call outs to the re-mote station. Filter change outs are now carried out on a routine maintenance schedule.