Water pretreatment methods can include clarification or lime softening, followed by several stages of filtration. The filtration can include the use of multimedia filters, carbon filters, cartridge filters and microfilters. UV sterilizers can also be installed after cartridge filtration in an effort to minimize bacterial growth.
With water pretreatment filter aids, the removal efficiency of the multimedia filters can be improved, but the amount of filter aid required is a function of feed water quality. Without active control of filter aid addition, a system will always produce less-than-optimal water, and there is a risk of fouling the membrane system with polymers.
Nalco Water?s patented3D TRASAR? Technology for Membranesactively monitors the concentration of polymer, controls the polymer residual levels and actively optimizes the performance of a multimedia filter. 3D TRASAR permits the use of the most effective filter aids, while minimizing the risk of fouling the membranes.