What to do if filter plate fibers get into the nanofiltration membrane?
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Our nanofiltration membranes are not cleaning effectively; upon opening the membrane housings, sticky substances were found at the membrane tips. Analysis revealed that these were filter plate fibers remaining from the plate and frame filtration process. I would like to ask the experts how to clean these membranes thoroughly.
It’s best to remove that thing, rinse it off, and wash the membrane thoroughly with alkali. I’m not sure what kind of filter media you’re referring to, but it certainly shouldn’t be present at the membrane head. Is the membrane’s safety filter damaged? Moreover, material that has only passed through the plate and frame filter should not be fed directly into the nanofiltration membrane; the pretreatment process wasn’t done properly. Such issues will keep occurring in the future – there must be a problem with your process!
The filter plate fibers are difficult to clean. There must be some pre-treatment between the filter press and the nanofiltration membrane; if the material goes straight to the nanofiltration membrane, it’s strange if it doesn’t get clogged.
So what is used for preprocessing? We have only one security filter, which is a needle-woven nylon filter bag with a 10-micron rating. Are there any additional processing steps needed?
What is the molecular weight cutoff of your nanofiltration membranes at the moment, or what is their pore size? It is best to perform ultrafiltration first before nanofiltration. It’s good to know this in order to choose the preprocessing method. If it’s not possible, you can temporarily replace your safety filters with folded filter elements of 0.45 microns; these should have a retention rate of over 95%. The material should be chosen based on your specific materials. It’s advisable to use your current safety filters to filter the fluid before it reaches the membrane.
If the pre-treatment is not done properly, no matter how good the cleaning agents and cleaning procedures are, they won’t be able to resolve the underlying problem. Therefore, it’s necessary to identify the main issue first; if it indeed is a problem with the pre-treatment, it should be addressed as soon as possible, otherwise the membrane will still become clogged.
For the clogging of filter plate fibers, it is recommended to use ultrasonic cleaning, with an alkaline cleaning agent. Note: The frequency of ultrasonic waves and the pH of alkaline detergents need to be properly controlled. In addition, a filter should be installed after plate and frame filtration, before nanofiltration