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1. What Is A Hollow Fiber Membrane?

Hollow fiber membrane refers to a membrane that looks like a fiber and has a self-supporting function. Hollow membrane filter is mainly processed into hollow fiber filaments with polysulfone and dimethylacetamide as raw materials, which have selective permeability characteristics. Hollow fiber filaments are relatively small in diameter, and are usually packed in fiber bundles of several meters, one end is sealed, and the other end is bonded with resin.

2. How Does Hollow Fiber Membrane Work?

The fiber membrane separation process with pressure as the driving force. Under a certain pressure, when the original liquid flows through the membrane surface, the densely packed many small micropores on the ultrafiltration membrane surface only allow water and small molecules to pass through and become permeate. The substance in the original solution whose volume is larger than the pore size of the membrane surface is trapped on the inlet side of the membrane and becomes a concentrated solution. Moreover, the hollow fiber filtration is performed at room temperature and low pressure, with low energy consumption, no heating, no need to add medicines to achieve the purposes of separation, concentration, separation, purification and classification. It can effectively remove particles, colloids, bacteria and macromolecular organics in the water. Ultrafiltration membranes (uf hollow fiber membrane) can be widely used in the separation, concentration and purification of substances.

3. Hollow Fiber Membrane Advantages

A. High filtration accuracy: The hollow fiber membrane of 0.03 microns can remove suspended particle impurities larger than 0.03 microns in water, especially in the wastewater regeneration and reuse technology, the removal rate of  total number of bacteria can reach 99.99%, and the removal rate of coliforms can reach 100 %.

B. High packing density: Among the membrane elements per unit volume, the hollow fiber membrane has the largest effective membrane area and the highest filtration and separation efficiency, which greatly reduces the footprint of membrane filtration equipment, saves civil engineering costs, and reduces investment , reduce operating costs.

C. Low filtration pressure: usually 0.05-0.08Mpa, which reduces energy consumption, investment and operating costs.

D. Easy to clean: since the structure of hollow fiber membrane is a single skin layer, the hollow fiber membrane can be backwashed and chemically cleaned.The best cleaning effect can be obtained by using this cleaning method, which can maximize the recovery of membrane performance, prolong the service life of membrane, reduce the labor intensity of operation, and reduce the operation cost.

E. Repairable: hollow fiber membrane element is composed of thousands or tens of thousands of hollow fiber filaments. Once a few fibers are damaged, they can be detected by certain methods, and the membrane components can be repaired. The repaired membrane components can continue to be used without any influence on the separation effect.

4. What's the Application of Hollow Fiber Membrane?

• Advanced sewage treatment and reuse in municipal, electric power, steel, petrochemical, textile, food and other fields and water treatment for production processes.
• Municipal water supply purification treatment.
• Seawater desalination and reverse osmosis system pretreatment.
• Purification, concentration and separation in food and biopharmaceutical fields.

5. What are the Classifications of Hollow Fiber Membranes?

According to different cross-sectional structures, hollow fiber membranes can be divided into single-channel hollow fiber membranes and multi-channel hollow fiber membranes.
There are many types and functions of hollow fiber membranes, and different classification methods are used to divide them into reverse osmosis membranes, ultrafiltration membrane, microporous filtration membranes, dialysis membranes and gas separation membranes.

6. What are the requirements for the influent water quality of  hollow fiber ultrafiltration membrane?

A. Temperature
The hollow fiber ultrafiltration membrane has a great influence on the inlet water temperature,.As the water temperature increases, the water permeability will also increase. If the temperature is too high, it will affect the performance of the membrane. Therefore, when the temperature is too high, measures should be taken to reduce the water temperature.

B. pH value
Hollow fiber ultrafiltration membranes have different pH requirements for different materials. PAN or PVDF materials have a pH of about 2-12, and cellulose acetate materials have a pH of about 4-6.

C. Microbial removal
Add NaClO oxidant in water: 1~5mg/1 concentration.
Because the raw water contains bacteria, etc., some microorganisms and bacteria remaining in the membrane system can be removed by adding 03 oxidant. If left untreated, bacteria will multiply and grow, which can lead to clogging of the ultrafiltration micropores, and in severe cases, the hollow fiber membranes will be completely blocked. Therefore, attention must be paid to removing bacteria in the raw water.

D. Turbidity 
When suspended solids, microorganisms, etc. and other impurities in the raw water are mixed, it will cause the water to form a kind of turbidity, which is also called turbidity by some people. The turbidity is generally set below 5 degrees.

E. Suspended matter and colloid
The hollow fiber ultrafiltration membrane is very effective for removing fine particles and colloids. Some particularly charged colloids are harmful to hollow fiber ultrafiltration membranes. Flocculant is a kind of high molecular polymer that can form hydrogen bonds to improve the colloid, but it cannot be completely removed. After testing by professionals, several methods have been found to be better. When the flocculant is added, the PH regulator bleaching powder, lime, sodium carbonate, oxidizer chlorine, etc. can be added at the same time to effectively improve the coagulation effect.