Ultrafiltration removes all foreign bodies. Pollutants filtered out of water by membranes with ultrafine pores. This process is a physical one. It finds residue-free. Without the use of chemical agents instead.
– Read also – Medical concerns about reverse osmosis systems
– Read also – Proper sizing of reverse osmosis systems
– Read also – Correct setting of reverse osmosis systems for home use
Pore size in ultrafiltration is between 0.01 µm and 0.05 µm. These are orders of magnitude in the range of one to five hundred thousandths of a millimeter. In practice, tubes made of ceramics or plastic are used, which have an inner diameter of about 0.5 to 2 mm. These tubes are arranged in bundles, which ensures that larger volumes of water can be filtered. By bundling many individual tubes, a sufficient flow rate is achieved.
The interesting thing about this pore size is that pathogens are also reliably filtered out. Bacteria usually have a size of 0.5 µm to 1.5 µm, even smaller germs such as Bacterium subtilis (0.3 µm) are still reliably retained. Filtered out thus:
– all substances whose molecules are larger than 0.05 µm – all bacteria – all protozoa, anthrax spores, etc.
Even foreign substances contained in water can be safely and reliably removed down to a molecular size of 0.05 µm. This mainly concerns turbidity and substances that form a covering layer, which have a negative effect on the taste and color of the water. Salts dissolved in the water. Minerals, however, remain intact. Only some types of viruses can pass through the filters, since viruses are between 15 and about 500 nm in size, i.E. Much smaller than bacteria.
Reverse osmosis systems
Reverse osmosis systems, on the other hand, work on a different principle. They produce ultrapure water that is free of all substances foreign to water, but also of salts and minerals. A carbon filter is usually connected upstream, which improves the water quality to such an extent that the membrane is protected and has a higher capacity.
The pure water, which results from the reverse osmosis, does not contain any minerals and salts. It is comparable to distilled water. There are serious medical concerns with drinking against this.
Conversely, if the system is set to retain salts, this is again at the expense of the filtering effect.
Comparison of both methods in practice
Ultrafiltration reliably and safely removes all pathogens and pollutants with higher molecular sizes from tap water. Only some types of viruses may still be present in the water, but in greatly reduced concentrations. The technology is simple and not very susceptible and is also suitable for continuous use – it is not for nothing that ultrafilters are also used in trekking.
The disadvantage of reverse osmosis systems is that a biofilm of bacteria can form on the membrane, which are retained but find a rich supply of nutrients. They multiply strongly there and can break through production or use-related defects into the drinking water. This means a high risk. In addition, there is the medical effect.
Reverse osmosis systems are also more expensive to purchase, require more energy and have a very high water consumption (up to ten times the drinking water withdrawal). Osmosis water can also attack stainless steel and other sensitive materials, as it reacts very aggressively, just like distilled water.