1. Causing harm

01 Decreased water production and increased pressure drop: The proliferation and metabolism of a large number of microorganisms within the membrane and components produce a significant amount of colloidal substances, leading to membrane blockage. This increases the pressure drop in the feedwater, resulting in reduced water production.

02 Frequent replacement of security filter cartridges due to blockage The biological biofilm formed by microbial metabolism has strong粘性 and is largely unaffected by water flow shear stress. Once formed, it is difficult to remove through conventional methods such as backwashing or forward washing, and long-term accumulation leads to the formation of biological sludge. Security filters have high filtration precision and are sensitive to changes in flux caused by microbial growth. Macro-level manifestations include a rapid increase in filter cartridge pressure drop within a short period, requiring replacement when it reaches 0.1 MPa. During spring and summer, as water temperatures continue to rise, microbial reproduction accelerates, and filter cartridge blockage becomes more pronounced.

03 Excessive microorganisms in the produced water Reverse osmosis membranes have small pore sizes (approximately 10 Å), enabling them to effectively remove dissolved salts, colloids, microorganisms, and organic matter from water (with removal rates as high as 97–98%). However, excessive microbial proliferation can damage membrane performance, leading to excessive microorganisms in the produced water.

04 Shortened membrane lifespan Acetate cellulose membrane systems are currently the most commonly used and cost-effective reverse osmosis systems in ultra-pure water production. However, one of their drawbacks is poor resistance to microbial corrosion. Excessive microbial proliferation can damage reverse osmosis membranes, erode the desalination layer, reduce desalination efficiency, shorten membrane lifespan, compromise membrane structural integrity, and even cause major system failures.

2. Treatment Measures

01 Disinfection in the Pretreatment System To prevent microbial contamination, effective disinfection measures are typically employed, including conventional methods such as chlorine gas, NaClO, ClO₂, KMnO₄, H₂O₂, O₃, and ultraviolet irradiation. The key control points are selecting appropriate disinfectants, ensuring sufficient contact time, and using oxidative disinfectants in the pretreatment stage to control microorganisms and maintain them in an inhibited state.

02 Pre-treatment Chemical Dosage Control During the pre-treatment stage, PAC/PAM or PAFC/PAM are commonly used for flocculation and sedimentation treatment. The dosage of PAM must be strictly controlled to prevent excessive use from causing microbial proliferation.

03 Operational Equipment Disinfection Treatment During system operation, disinfection treatment must be regularly performed on chemical dosing tanks and water tanks to reduce bacterial proliferation.