One of the most common questions when choosing a water treatment system is the difference between reverse osmosis and ultrafiltration. Both technologies are membrane-based but are designed for completely different contamination profiles; using one in place of the other usually leads to both unnecessary costs and unexpected performance problems.
Ultrafiltration membranes have a pore size of about 0.01 micron. This scale is more than enough to retain bacteria, viruses, suspended solids and large organic molecules; it creates a microbiological barrier without chemicals. However, dissolved salts, hardness ions and conductivity pass through this membrane. In other words, if your water's problem is turbidity and microorganisms, ultrafiltration is the right choice.
Reverse osmosis, on the other hand, also retains dissolved salts with its semi-permeable membrane and reduces conductivity by 90-99%. For boiler feed water, production processes that require pure water, and brackish or saline source water, it is often the only solution. In return, it means higher pressure, and therefore more energy and some concentrate wastewater.
The decision should be based on measurement, not guesswork. The conductivity, hardness, turbidity and organic matter values in your water analysis clearly show which technology is needed. In most industrial plants, the right answer is not a single technology but a hybrid arrangement in which ultrafiltration works as pretreatment for reverse osmosis.
