Product Introduction

Ultrafiltration technology utilizes selective porous membranes as the separation medium. Under a driving force such as pressure difference, the solution passes through the membrane, allowing low-molecular-weight solutes to permeate while retaining high-molecular-weight substances. This achieves effective separation, concentration, and purification.

Ultrafiltration can almost completely intercept suspended solids, colloids, microorganisms, large organic molecules, and bacteria in water, while allowing inorganic salts and small organic molecules to pass through. This technology is now widely recognized across diverse water treatment and liquid separation applications.

Membrane Material

Common ultrafiltration membrane materials include PVDF, PAN, PES, PS, CA, PE, PP, and PVC. While polysulfone, cellulose acetate, and polypropylene membranes once dominated the market, polyvinylidene fluoride (PVDF) and polyethersulfone (PES) have become the most widely used materials today. Among them, PVDF is increasingly favored for its unparalleled advantages.

Advantages of PVDF Membrane Material

The most significant characteristic of PVDF is its extremely high chemical stability, which provides outstanding oxidant resistance and acid-alkali tolerance. During water treatment, microorganisms and organic matter inevitably adhere to the membrane surface, gradually blocking pores and reducing separation performance. The most effective cleaning method is oxidant washing — but oxidants can damage many membrane materials. PVDF's resistance to oxidants such as sodium hypochlorite is more than 10 times that of PES and PS materials, greatly extending membrane service life.

Additionally, while both PS and PVDF offer high strength, PVDF also provides exceptional flexibility. This flexibility is critical during air scrubbing and cleaning processes, making PVDF the preferred choice for membrane bioreactors (MBR) and externally pressurized filtration modules. Field investigations confirm that PVDF membranes have the lowest fiber breakage rate among all membrane materials.

Product Characteristics

Our PVDF ultrafiltration membrane modules are available in two series with membrane areas of 53㎡ and 75㎡. Thanks to their unique oxidant resistance and easy-cleaning properties, they are widely applicable to groundwater treatment, surface water treatment, sewage treatment, reclaimed water reuse, and tap water purification.

Key advantages include:

High oxidant and cleaning resistance — PVDF's chemical stability allows cleaning with high-concentration oxidants, effectively preventing bacterial and microbial proliferation

High flux — high porosity enables superior throughput

High strength with excellent flexibility — air scrubbing during cleaning without risk of fiber breakage

Strong anti-fouling performance — hydrophilic modification significantly improves fouling resistance

Excellent water quality — small nominal pore size removes virtually all suspended particles, microorganisms, colloids, and bacteria

Long service life — outside-in structure resists clogging, offers larger filtration area, higher retention capacity, and thorough cleaning capability

Performance Parameters

Operating Conditions

Process Design Conditions

Chemical Cleaning Guidelines

Thanks to PVDF's excellent anti-fouling properties, physical cleaning generally achieves satisfactory results. Chemical cleaning should be performed when physical methods are insufficient.

Cleaning temperature: 20-30℃ for standard solutions.

Chemical Enhanced Backwash: Appropriate chemicals are introduced from the feed inlet and circulated through the membrane to remove surface and internal pollutants. Maintaining a reasonable cleaning frequency helps extend membrane service life.

Full Chemical Cleaning: Required when TMP increases by 0.1 MPa above the initial value and cannot be restored by backwash, gas scrubbing, or dispersive cleaning.

Cleaning methods:

Acid wash: 0.1wt% HCl or 1-2wt% citric acid solution, circulate for approximately 60 minutes. Suitable for removing inorganic scale and deposits.

Alkali wash: 0.1wt% NaOH + 0.1% NaClO (effective chlorine) solution, circulate under < 0.05 MPa for 30 minutes, then soak for 30-60 minutes. Suitable for removing organic pollutants.

NaClO wash: 500-1000 ppm NaClO solution, circulate for 60-90 minutes. Suitable for removing microbial pollutants.

Important: When switching between acid and alkali cleaning agents, first drain the previous solution from the membrane module to prevent dilution. After each cleaning step, rinse thoroughly with UF or RO water until the internal pH reaches 7.