The past 30 years have witnessed the rapid development of ultrafiltration technology, with ultrafiltration separation technology widely applied in drinking water preparation, food industry, pharmaceutical industry, industrial wastewater treatment (electrophoretic painting wastewater treatment, oily wastewater treatment, polyvinyl alcohol (PVA) containing wastewater treatment, fiber processing oil wastewater treatment, color and dyeing wastewater treatment, pulp wastewater treatment, leather wastewater treatment, optical glass grinding wastewater treatment, photographic industry wastewater treatment), radioactive wastewater treatment, metal processing coatings, biological product processing, petroleum processing, and other fields. Large-scale water treatment is usually focused on the following aspects: drinking water supply terminals, surface water treatment, seawater treatment, and fluid reuse.

　　(1) Drinking water treatment

　　Due to increasingly stringent requirements for drinking water quality, water treatment companies are investing more and more effort in controlling the amount of microorganisms present in the water supply network. To achieve this, one method is to conduct expensive and frequent water quality tests, or to set up barriers at the water supply terminal to prevent the entry of bacteria and viruses.

　　Using a UF system, such a barrier can be easily constructed. The ultrafiltration membrane can achieve a 6log removal rate for bacteria and a 4log removal rate for viruses, so water plants and water users no longer need to worry about bacteria and viruses. Since the quality of drinking water itself is very high (both turbidity and suspended solids are very low), the membrane system can use a very high membrane flux, reaching 135 liters/m².hour. At the same time, with higher influent conditions, the backwashing frequency and chemical enhanced backwashing frequency can be very low, and the water yield can reach 99%. If necessary, a secondary ultrafiltration system can be set up to further reuse the backwash water from the first stage.

　　2) Surface water treatment

　　UF systems are widely used in surface water treatment, with the treated water used for irrigation or as feed water for reverse osmosis to prepare industrial water.

　　In the Netherlands, there are more and more such plants. This technology provides a new way of industrial water use, that is, instead of buying increasingly expensive drinking water, it uses nearby surface water after treatment.

　　(3) Seawater desalination

　　The Middle East is the area with the most severe water shortage. To solve this problem, people usually used distillation technology. Since the 1960s, membrane technology has been used to solve the water shortage problem in these countries. However, many reverse osmosis seawater desalination systems face the problem of serious membrane fouling. This is mainly because traditional pretreatment methods for reverse osmosis systems cannot provide reliable influent water quality. Therefore, the vast majority of desalination plants operate far below their designed water output, and some plants even fail to reach 30% of their initial design output.

　　Research on small-scale desalination devices clearly shows that ultrafiltration systems can reliably control the water quality of seawater, providing high-quality feed water for reverse osmosis systems. Long-term tests also show that the SDI value of the ultrafiltration system can be well controlled below 2. These tests do not require any pretreatment before the ultrafiltration system and are applicable to various seawater qualities.

　　(4) Wastewater reuse

　　Western countries have spent a lot of effort treating wastewater, but after treatment, they simply discharge it into surface water sources through drainage networks, which is very unreasonable. Once again, ultrafiltration, due to its price advantage, provides an attractive solution for wastewater reuse.

　　In fact, wastewater discharged from municipal wastewater treatment plants and factories is a very good water resource as industrial water, or even drinking water. This is technically feasible, but Western users find it very difficult to believe. It is more of a psychological problem than a technical one. However, a plant with a capacity of 850 tons/hour is currently under construction in Windhoek, Namibia, using membrane technology to reuse the effluent from a wastewater treatment plant as drinking water.