Absolute filtration ensures good and stable water quality
For a few hundred years, sand filters, activated carbon filters and other media filters have been used for filtration in connection with water treatment. The disadvantage of these methods is that the quality of the water quality must be stable to provide a stable, filtered quality.
A stable feed water quality is not always possible to maintain. At the same time, media filters do not result in an absolute filtering. The typical media filtration leaves a water quality of particles between 0.5 and 20 microns.
Ultrafiltration does not require the same stability of the feed water quality. It does not matter that the water is of a poorer quality from one day to the next. In the ultrafiltration proces, the raw water is pressed through plastic pipes under high pressure. These tubes have a porous inside with very fine pores that hold particles down to 0.01 microns, which means that bacteria, viruses and colloids are also retained.
Advantages of ultrafiltration:
- Good and stable water quality, whether measured as turbidity, SDI or LRV
- Tolerance to changes in the feed water quality
- No need for or use of pre-treatment chemicals (polymers, coagulants, pH adjustment)
- Less space-consuming and lower weight than media filters
When ultrafiltration is used as pre-treatment for reverse osmosis installations, the risk of fouling of the membranes is reduced, which means:
- Fewer cleaning processes and shorter intervals between cleanings and thus reduced operating costs and less downtime periods
- The ability to optimize the RO installation by using fewer membranes, smaller pumps, etc.