Pre-filtration methods and precautions for microporous membranes

Prefiltration of microporous filtration membranes refers to the process of removing some larger particles or contaminants before the feed solution enters the formal microporous filtration membrane. Prefiltration can protect the membrane from contamination and improve its service life and performance. Helps reduce the load of particles and larger materials that can clog or damage membranes, thereby improving the overall filtration process.

What are the commonly used pre-filtering methods?

1. Depth filtration. The depth filter used is composed of particle layers of different sizes. After the filtrate passes through, larger particles are captured on the surface, and smaller particles are captured on the surface or deep inside the filter. This Most of these filters are made of materials such as cellulose, glass fiber or diatomaceous earth. Their working principle is size exclusion and particle capture mechanism. After the particles and larger pollutants are removed by the depth filter, they will Greatly reduce the pressure on the microporous filter membrane.

2. Cartridge filtration, using a cartridge filter to pre-filter the solution, the contaminants are retained on the filter surface or within the filter matrix. This filter is composed of a cylindrical shell filled with filter media, including polypropylene. , polyethersulfone or nylon and other materials, including pleated, wound or melt-blown filter cartridges, etc. According to the shape and size of the filtered particles, a cartridge filter with a specific pore size can be selected to achieve the required Particle removal efficiency.

3. Bag filter. Bag filter is a large fabric structure filter with different materials, sizes and micron grades. It is usually used in pre-filtration applications. After the feed solution passes through the bag filter, the contaminants are captured. On the inside surface of the bag, this type of bag filter has a high dirt-holding capacity, making it suitable for high-flow or larger-volume applications.

4. Centrifugal separation. A centrifugal separator is a device that uses centrifugal force to separate particles from the feed solution. The feed solution enters the centrifuge or centrifugal separator. The high-speed rotation causes the particles to settle or migrate to the surrounding walls of the device. The clarified solution is collected in the middle, while the separated particles are discharged as a waste stream. This centrifugal separation technology is very effective for larger particles and higher concentrations of solids.

What matters must be paid attention to when using pre-filtering?

1. Particle size and loading. It is necessary to understand the particle size distribution and concentration of contaminants in the feed solution, so as to select a pre-filtration method and filter media that can effectively capture and retain the target particle size.

2. Compatibility, ensure that the prefiltration method and filter media are compatible with the characteristics of the feed solution, including pH, temperature and chemical compatibility. Some solutions may require specialized filters to handle specific chemical or biological components.

3. Filter selection, select the appropriate pre-filtration method, filter media and pore size based on the specific requirements of the application, required particle removal efficiency and flow rate.

4. Maintenance and replacement, and regular monitoring of pre-filtration system and filter performance. Replace or clean the filter according to the manufacturer's recommendations or when the pressure drop across the filter exceeds acceptable levels.

5. System design, optimize the design of the pre-filtration system to ensure proper flow distribution, minimize turbulence, and prevent bypass or channeling of the feed solution.

Before using the microporous filtration membrane, implement effective pre-filtration to remove part of the larger particulate matter, so that the membrane can filter out target particles in a more targeted manner, significantly improving the service life and performance of the microporous filtration membrane, and reducing membrane cleaning and replacement. frequency while ensuring consistent filtration efficiency.