Thread Content
1. Inadequate monitoring of residual chlorine in ultra-pure water treatment equipment: The membrane can be damaged by residual chlorine if the pump used to add NaHSO3 fails, if the chemical solution loses its effectiveness, or when the activated carbon becomes saturated. 2. Inadequate disinfection and maintenance of ultra-pure water equipment leads to microbial contamination. This is a common problem when using composite polyamide membranes; since these membranes are not resistant to residual chlorine, disinfectants such as chlorine are not used properly during operation. Coupled with users’ insufficient attention to preventing microbial growth, this can easily result in microbial contamination. The microbial levels in pure water produced by many manufacturers are above the acceptable limits, which is caused by inadequate disinfection and maintenance. The main issues are as follows: at the time of departure from the factory, the RO equipment was not treated with disinfectant; after installation, the entire piping system and pre-treatment equipment were not disinfected; no disinfection or maintenance measures were taken during intermittent operation; the pre-treatment equipment and ultrapure water equipment were not disinfected and maintained on a regular basis; and the disinfectant used was either ineffective or had an insufficient concentration. 3. Incorrect method of shutting down the ultra-pure water equipment. A. Rapid pressure reduction during shutdown did not result in thorough flushing. Since the concentration of inorganic salts on the concentrated side of the membrane is higher than that in the raw water, scaling occurs easily, contaminating the membrane. B. Rinse with pre-treated water to which chemical reagents have been added. Water containing chemical reagents may cause membrane fouling during equipment shutdown.