How to Prevent and Control Microbial Fouling of RO Membranes in the Hot Summer?
The hot summer is accompanied by high temperature. While people are troubled by the heat, microorganisms find a breeding ground. In hot summer, how to control microbial fouling with RO membranes?
What is the relationship between high temperature and microbial fouling?
It is well known that raw water contains a large number of microorganisms, including bacteria, algae, fungi and their spores, and viruses. Under suitable conditions, these microorganisms are able to rapidly metabolize on the surface of the RO membrane, forming a biofilm that severely affects system performance.
Being humid and dark in the summer, the RO system provides an ideal growth environment for microorganisms; the feedwater temperature of 15~35℃ is basically the most suitable for microbial growth. In addition, water quality containing high-concentration organic matters and nutrients, as well as the increased water temperature in summer, also facilitate the massive reproduction of microorganisms.
What are the impacts of microbial fouling?
Microbial fouling generally occurs during the shutdown of the RO system that use surface water, reclaimed water (tertiary wastewater), and seawater as the feedwater source. It can rapidly increase the pressure difference between the feedwater and concentrated water of the RO system, reduce the water production, and causes organic contamination. Additionally, once a biofilm is formed, it is very difficult to clean. This is because the biofilm is neither soluble in acid nor easily soluble in alkali, thereby providing protection for microorganisms. If the biofilm is not completely removed, it will be contaminated again in a short period.
Guide to solve microbial fouling
Strengthen disinfection and sterilization
Common sterilization methods include chemical sterilization and physical sterilization. Chemical sterilization options include: chlorine sterilization such as sodium hypochlorite, and chloramine, oxidative sterilization such as ozone and hydrogen peroxide, as well as non-oxidizing sterilization such as isothiazolinone. Physical sterilization options include: ultraviolet irradiation and high-temperature heat disinfection.
Effective cleaning strategies
Microbial fouling should be cleaned promptly in the early stages. The RO membrane system that has suffered from microbial fouling shall be processed with systematic disinfection after chemical cleaning. The pretreatment should be improved to prevent another fouling.
Use anti-fouling membrane elements
Once a biofilm is formed, it is relatively difficult to clean. It is recommended to select VONTRON's PURO series anti-fouling RO membrane elements for the system that is prone to microbial fouling. With strong chemical cleaning resistance, and good cleaning recovery effect, these elements adopt LD low-pressure differential grid design with superior anti-fouling capability.
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