As a deep filtration means, reverse osmosis membrane will inevitably have colloids, microorganisms, impurity particles and insoluble salts precipitated on its surface.
Therefore, once a reverse osmosis unit is put into use, it will eventually need to be cleaned, only the length of the cleaning cycle is different. The cleaning of reverse osmosis membrane element is divided into two ways: online cleaning and offline cleaning.
Online cleaning is the conventional cleaning method, mainly for the maintenance and repair of reverse osmosis system.
The biggest problem of online cleaning is that the concentration of cleaning solution at the end of the cleaning direction will gradually decrease.
When the reverse osmosis system runs for more than a certain period or the reverse osmosis membrane pollution is serious, the online cleaning is unable to help, so it is necessary to clean the reverse osmosis membrane element offline.
Conditions for off-line cleaning of reverse osmosis membrane
1、When the pressure difference of a single section of the reverse osmosis system is more than two times the pressure difference value of a single section at the beginning of system operation.
2、Reverse osmosis system water production drops by more than 30%.
3、The weight of single reverse osmosis membrane element exceeds the normal value by more than 3bar.
4、The performance of reverse osmosis system cannot be recovered by online cleaning.
The characteristics of off-line cleaning, when online cleaning, for different locations of the membrane target difference.
Since there is usually not one membrane element in a membrane vessel, the contamination of these elements also differs. When using the same concentration of cleaning solution to clean different contaminated membranes,
it will inevitably cause some membranes to be over-cleaned and some to be under-cleaned, so the cleaning effect is poor and cross-contamination is also easy to form.
The main feature of the off-line cleaning method is that it replaces the RO membranes used in the field with spare membranes without affecting the normal production of the users.
Single RO membrane cleaning is carried out with a special cleaning device, which can be targeted to handle membranes with different contamination scenarios, and can easily achieve forward and backward cleaning of RO membranes with sufficient cleaning flow for a single membrane.
The cleaning status of the RO membrane can be monitored at any time during the cleaning process, and the cleaning level can be decided according to the actual situation.
By analyzing the main components of contaminants in the cleaning solution, we can determine the contaminants in the system and propose adjustments to the system accordingly in order to extend the service life of the customer’s system.
Offline cleaning steps of reverse osmosis membrane
1、Firstly replace the membrane element to be cleaned on the reverse osmosis system with a spare membrane element with good performance to ensure that the reverse osmosis system does not stop running and that the whole production process is continuously stable.
2、Test the performance of the reverse osmosis membrane elements:
3, system cleaning before understanding the current operating conditions of the system; collection of operating reverse osmosis system indicators of each parameter, make original records.
4、According to the user raw water full analysis report, performance test results and the system information understood to judge the cleaning process.
5, the identification of pollutants. First of all, according to the analysis results of 3.4 preliminary determination, and then through special equipment, apparatus for further verification to determine the specific type of pollutants.
6, according to the results of the analysis, to determine the required cleaning formula, concentration.
7, in the reverse osmosis special cleaning equipment with the above cleaning agents combined with material treatment cleaning means for experimental cleaning, in order to select the appropriate cleaning formula and cleaning procedures.
8、Determine the cleaning method for all the above membrane elements.
9, the cleaned membrane elements into the test platform to test and make records, does not meet the requirements will be resent to the cleaning equipment for processing.