Comparison of surface water pre-treatments for ultrafiltration

The River Trent runs through both Severn Trent and Anglian Water regions, and has been identified as a potential new water resource for both companies. It contains treated effluent from 4 million people and industry in the Midlands. As part of an ongoing project, comparing conventional water treatment processes with membrane technologies for treatment of the River Trent to potable standards, pre-treatment processes for ultrafiltration are being compared. Depth filtration gave the best particulate removal, whereas the package filters performed as per the manufacturers' specifications. Package filters tended to increase the small particulate fraction between 2-5 μm, so although these may remove problems caused by large particles they could aggravate pore blocking and membrane penetration related fouling. There is a direct trade off between the capital cost of pre-treatments vs. increased running costs (higher TMPs, more frequent cleaning, extensive cleaning requirements).