Wuhan Biwofeng Environmental Engineering Co., Ltd

Composite ultrafiltration membrane system

2022-08-29 08:36

Materials and Technology

Tubular ultrafiltration membrane adopts a unique composite structure, which is divided into supporting material and surface membrane material.

Ultrahigh molecular weight polyethylene powder (UHMWPE) is sintered as the supporting material, and its internal structure is hot melt multidirectional uniform supporting skeleton pore structure, which has outstanding advantages such as high toughness, high wear resistance and high density. The formed membrane tube support has high porosity, good strength, long service life and superior processability.

Modified polyvinylidene fluoride (PVDF) is used as the surface film material, which has good hydrophilicity, acid and alkali resistance, oxidation resistance, easy film formation and stable physical and chemical properties. PVDF is embedded in the gap of PE support after membrane formation, and forms a firm anchor link with it. This composite structure makes the product obtain a perfect combination of excellent filtration performance and structural strength.

Characteristics of composite tubular ultrafiltration membrane system

The composite tube supermembrane system adopts crossflow filtration mode. When the water flow rate in the membrane tube is high (flow rate > 3.0 m/s), the intercepted objects attached to the membrane surface are taken away by the tangential force of water flow, so that they cannot or exist in a small amount on the membrane surface. Compared with the external pressure membrane, this operation mode can greatly slow down the attenuation of membrane flux.

Advantages of composite tubular ultrafiltration membrane system

1. The tubular membrane with PE sintered tube as the support is different from the tubular membrane with nonwoven fabric as the support. Because of the different bonding degree between the support and the membrane, it has unique reverse washing ability.

2. The interception mechanism of the composite tubular membrane belongs to surface interception, That is, when the filter membrane is running, suspended particles and colloids larger than the pore size of the filter membrane in raw water are intercepted on the membrane surface, These intercepted objects cannot enter the deep structure of the membrane, Therefore, it is easy to be taken away from the membrane surface by reverse flushing and highspeed circulating tangential water flow, thus achieving the purpose of antifouling, At present, the mainstream tubular microfiltration membrane in the market is coated with sponge filter material on the inner surface of PE sintered tube. This deep interception filtration method is easy to make the intercepted material enter the membrane and difficult to elute, which is manifested in large initial flow rate but rapid attenuation, increased cleaning frequency and reduced membrane life.

3. Because the composite tube membrane system has pulse reverse flushing ability, it does not need to make the circulating flow rate too large, which is generally 3.0-4m/s. At the same time, the circulating loop can effectively utilize the head kinetic energy of concentrated water, thus greatly reducing the power consumption of circulating water pump and saving energy in the system.

Principle of tubular ultrafiltration membrane equipment

The raw water to be treated enters the membrane module for filtration after being pressurized by the makeup water pump, Substances with particle size larger than membrane pore size in raw water, such as macromolecular organic matter, colloid, suspended solids, fungi and other impurities, are intercepted by ultrafiltration membrane. Water and small solute particles form produced water through ultrafiltration membrane, and raw water containing impurities is continuously concentrated by ultrafiltration membrane to form concentrated water. When concentrated water accumulates to a certain extent, in order to avoid membrane tube blockage, open concentrated water discharge valve to discharge concentrated water to filter press or regulating pool.

Performance comparison between composite tubular membrane and well-known similar products abroad

Parameters of porex membrane module in the United States

Parameters of BERGHOF membrane module in Germany

Performance parameters of composite tubular membrane