Analysis of the reasons for the decrease in flux of MBR hollow fiber membranes
Hollow fiber membranes are commonly used membrane components in MBR systems, but flux decline during operation is a common problem. The decrease in flux will lead to a decrease in system efficiency and an increase in operating costs, so it is important to analyze its causes and take effective countermeasures. The following are the main reasons for the decrease in flux of MBR hollow fiber membranes:
1. Membrane fouling
Membrane fouling is the main cause of flux decline and can be divided into the following types:
Biological contamination
Microorganisms such as bacteria and fungi form biofilms on the membrane surface
Accumulation of soluble microbial metabolites (SMP) and extracellular polymers (EPS)
organic pollution
The adsorption or accumulation of macromolecular organic substances such as proteins and polysaccharides
Colloidal particles and dissolved organic matter block membrane pores
Inorganic pollution
Precipitation and deposition of inorganic salts such as metal oxides and vitriol compounds
Scale formation leads to increased inorganic pollution
2. Membrane material properties
Hydrophobic membrane materials are more likely to be adsorbed by pollutants
The accumulation of pollutants on the rough membrane surface aggravates pollution
Small pore size membranes are easily clogged by fine particles
3. Operating conditions
Excessive high flux or transmembrane pressure accelerates contaminant deposition
Insufficient aeration causes sludge concentration and aggravates pollution
Changes in environmental conditions such as temperature and pH affect the properties of pollutants
By comprehensively analyzing the above reasons and taking targeted measures such as cleaning and optimizing operations, the flux decline of MBR hollow fiber membranes can be effectively controlled and slowed down.