The Advantages and Considerations of Hollow Fiber UF Membranes

The goal of hollow fiber ultrafiltration membranes is to achieve separation by allowing raw water to pass through the membrane at a certain pressure and flow rate, while contaminants in the water are prevented from passing through the membrane pores.

Using an asymmetric microporous structure and a semi-permeable membrane medium at room temperature, the basic idea is to use a cross-flow filtration mode that allows solvents and small molecules to pass through while trapping large molecules and particles like proteins, water-soluble polymers, and bacteria. This is done by relying on the pressure difference on both sides of the membrane as the driving force.

Only water molecules, trace elements, and beneficial mineral elements in water may flow through the tube wall of the ultrafiltration membrane’s approximately 6 billion 0.01-micrometer micropores. The ultrafiltration membrane may retain bacteria in addition to colloids, rust, suspended particles, silt, and big molecular organic compounds larger than bacteria, completing the purifying process.

One reasonably developed and sophisticated type of ultrafiltration technology is hollow fiber ultrafiltration membranes. The hollow fiber has an inner diameter of 0.3–1.4 mm and an outside diameter of 0.5–2.0 mm. The molecular weight of the material that was intercepted is used to represent the size of the micropores that cover the hollow fiber’s tube wall.

The molecular weight that is intercepted might range from several thousand to several hundred thousand. There are two forms of pressure in a hollow fiber: internal pressure and external pressure. Pressure is applied to the raw water either within or outside the fiber. Ultrafiltration is a dynamic filtration method that may remove compounds with concentration and long-term continuous operation without fouling the membrane surface.

Advantages

High strength: A single membrane may have a tensile strength of up to 6N, and its exceptional filtering efficiency and longevity can be attributed to its unique module structure and advanced membrane forming technology.

Good rigidity: With a maximum TMP of more than 2.5 bars and a highly compressible structure, the membrane is made to function at a pressure as low as 0.02 MPa in order to permeate enough water.

Excellent extensibility: The membrane may elongate up to 300%, and the membrane fiber does not strain or break often.

High crystallinity: The membrane exhibits superior mechanical strength, superior chemical resistance, and a longer service life when compared to comparable domestic goods.

High flow rate: At 25°C and 0.1MPa, the permeation flux surpasses 1000LMH.

Low-pressure drop: The membrane is prone to backwash because of its uneven and progressively narrower structure.

Problems with Hollow Fiber Ultrafiltration Membranes to Consider: Because bacteria and microorganisms have a significant potential for pollution and can create additional pollutants and foreign substances, the raw water should be sterilized with a bactericide before filtering, and an appropriate residual chlorine level should be maintained. coagulation and sedimentation, as well as pre-filtering to eliminate solid particles and suspended solids, When the colloid content is high, pre-treatment should be applied; otherwise, it will raise the hollow fiber membrane’s operating pressure and result in needless damage.

In order to guarantee the cleanliness of the membrane, the effectiveness of the membrane treatment operation, and to increase the membrane’s service life, timely backwashing, fast washing, and periodic chemical cleaning are useful. Additionally, dynamic filtering needs to be done on a frequent basis. To avoid severe impacts that might produce excessive pressure on the membrane and damage it, raise and drop the pressure carefully while starting and stopping the device.

It is commonly known that proper pre-treatment is necessary to guarantee reverse osmosis (RO) systems operate at their best. To guarantee optimal performance and membrane life, RO manufacturers always prescribe a set of incoming water parameters. Deviations from the criteria result in significant downtime and production harm.

It is not entirely safe to follow this guideline or any other parameters suggested by RO manufacturers with conventional pre-treatment. Owing to these drawbacks, membrane filtration—particularly ultrafiltration (UF)—is increasingly acknowledged as the ideal pre-treatment before reverse osmosis (RO).

Theoretically, the optimum pre-treatment before a reverse osmosis (RO) system is ultrafiltration (UF), which eliminates most of the potential causes of membrane fouling from the feed water, including particles, turbidity, bacteria, and big molecular weight organic matter.

By acting as a barrier filter, the UF holds onto any particles larger than 0.1 micron. This enables the RO to run at a higher design flux and therefore a larger total flow, or it can generate the same flow with less energy, or it may boost productivity. One might utilize a smaller RO in a fresh installation. The RO requires less membrane cleaning when UF pre-treatment is used, which lowers the amount of chemicals used and wastewater discharged. Another advantage is a longer membrane life.