Project

Rank Brimar use about 5m3 /h of high purity (>15MΩ .cm) water in the production of their cathode ray tubes. The original system consisted of two-bed deionisers with sub-micron cartridge filtration and a ring main with mixed bed polishing. The introduction of new, higher specification products demanded improved treated water purity and this lead to the addition of ultrafiltration. Seasonal variation in mains water quality caused membrane fouling resulting in extended down time and high maintenance costs. Whitewater was commissioned to investigate the problem and recommend a cost-effective solution.

Responsibilities

Site investigation, implementation of pilot plant trials, system design and specification.

Site investigations including water analyses, SDI monitoring and SEM examination showed that the principal problem was one of colloidal silica associated with seasonal algal activity in the reservoir. A pilot scale colloid adsorbing resin unit was installed and run in parallel with the ultrafiltration unit and demonstrated good removal of colloidal silica and significant improvements in SDI.

A full scale colloid adsorber was added to the treatment train upstream of the membrane ultrafiltration units. The result was increased ultrafilter throughput, reduced downtime for cleaning and extended membrane life. At the same time, the existing equipment was refurbished, the process route rationalised and a new control system added. The investment showed payback within two years.