Membrane Pretreatment Optimization
Is my reverse osmosis pretreatment effective?
How often you need to clean the membrane?
- If you must clean a membrane every one to three months, the estimated performance of the membrane is marginal.
- If you must clean a membrane every month or more, the estimated performance is inadequate.
(Source: 2. Glanz, D. and Herring, J., Proc. 57th International Water Conf., IWC-96-19, 153-161, (1996).)
What are pretreatment methods?
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. Ultraviolet (UV) sterilizers are also being installed after cartridge filtration in an effort to minimise bacterial growth. With pretreatment filter aids, we can improve the removal efficiency of the multimedia filters, but the amount of filter aid required is a function of feed water quality. Without active control of filter aid addition, you will always produce less-than-optimal water, and you also risk fouling the membrane system with polymers. Nalco Water's patented PT TRASAR (Traced Pretreatment Control) technology actively monitors the concentration of polymer, controls the polymer residual levels and actively optimizes the performance of a multimedia filter. PT TRASAR permits the use of the most effective filter aids, while minimising the risk of fouling the membranes.