Since hollow fiber ultrafiltration membrane is made of hollow fiber material, the residues in the water are removed by physical interception, and should be cleaned on time to ensure that the service life of hollow fiber ultrafiltration membrane increases according to the amount.
1. Configure the cleaning solution
The cleaning fluid is configured in an appropriate proportion.
2. Low flow input cleaning fluid
First, mix the cleaning fluid with the cleaning pump, and use a lower flow rate when preheating the cleaning fluid. Then replace the source water in the element with the lowest possible cleaning fluid pressure, and its working pressure only needs to be enough to make up for the loss from the incoming water to the concentrated water, that is, the working pressure must be low enough to not cause obvious infiltration of the permeate water. The actual operation of low pressure replacement can minimize the re-deposition of stains on the surface of hollow fiber ultrafiltration membrane, and discharge part of the concentrated water according to the situation to avoid dilution of the cleaning solution.
3. Circulatory system
When the raw water is replaced, the cleaning liquid should appear in the concentrated water pipeline, so that the cleaning liquid circulation system returns to the cleaning water storage tank to ensure that the cleaning liquid temperature moves at a uniform speed.
Stop the operation of the cleaning pump, so that hollow fiber ultrafiltration membrane is completely immersed in the cleaning solution. Sometimes soaking for about 1 hour is enough, but for difficult-to-remove contaminants, the soaking time must be increased, such as soaking for 10 to 15 hours or soaking for a stay. To better maintain the temperature throughout the soaking process, a very low circulation system flow rate can be selected.
5. High flow pump cycle
The high flow can wash away the contaminants that are being washed away by the cleaning fluid. If the environmental pollution is serious, please choose the specified flow rate of more than 50%, which is conducive to cleaning. At high flow standards, problems with excessive pressure drop may occur. The maximum allowable loss of the module is 1bar (15psi), and the maximum allowable loss of the multi-element high-pressure container is 3.5bar (50psi).
The standard permeate flow of pretreatment can be used to clean the cleaning fluid in the system unless corrosion is a problem.
To avoid deposits, the cleaning temperature should be at least 20°C. During the whole process of pickling and passivation, the pH value of the cleaning solution should be checked anytime and anywhere. When the acid is consumed by carbonate deposits, the cleaning tank should be filled with acid if the pH increases by more than 0.5 pH.
7. Cleaning the multi-stage system
In the flushing and soaking steps of a multi-stage system, all parts of all systems can be carried out at the same time, but the high-flow circulation system must be carried out in stages to ensure that the flow rate of the first stage of the circulation system is not too low, and the last stage is not too high. Different cleaning pumps can be set up for each pump cleaning each section or each flow regulation.
Timely cleaning of uf membrane module can maintain the service life, and an appropriate amount of cleaning and an appropriate amount of cleaning can save time and reduce damage to uf membrane module during the entire cleaning process. For different uf filter membrane, different cleaning methods can be used, for example, the tubular components can be mechanically cleaned with sponge balls, and the hollow fiber components can be backwashed. For the film used in the food industry, disinfection treatment (with NaOH and H2O2, etc.) is also required.