Chemical cleaning method for nanofiltration or reverse osmosis membranes

Abstract

The invention discloses a chemical cleaning method for nanofiltration or reverse osmosis membranes. The chemical cleaning method includes the following steps: (1) pickling the nanofiltration or reverse osmosis membranes by acidic solutions; (2) cleaning the nanofiltration or reverse osmosis membranes by product water after pickling; (3) performing alkali washing on the nanofiltration or reverse osmosis membranes by alkaline cleaning solutions; (4) cleaning the nanofiltration or reverse osmosis membranes by the product water after alkali washing to complete cleaning of the nanofiltration or reverse osmosis membranes. The chemical cleaning method has the advantages that various pollutants on the nanofiltration or reverse osmosis membranes can be efficiently removed, the operating pressure ofthe nanofiltration or reverse osmosis membranes can be reduced, the yield of clear liquid of the nanofiltration or reverse osmosis membranes can be increased, the service life of the nanofiltration or reverse osmosis membranes can be prolonged, the power consumption of the clear liquid can be lowered, and stable operation of landfill leachate treatment plants can be guaranteed; the chemical cleaning method has the advantages of simple process, convenience in operation, low cleaning cost, high cleaning efficiency, good cleaning effect, high application value, good application prospect and thelike.

Description

technical field [0001] The invention belongs to the technical field of landfill leachate treatment, and relates to a chemical cleaning method for nanofiltration and reverse osmosis membranes. Background technique [0002] In fresh landfill leachate, the B / C is high and the total hardness is high, so it needs to be treated by MBR, ultrafiltration, nanofiltration and reverse osmosis successively, among which nanofiltration / reverse osmosis membrane (NF / RO membrane) to treat the ultrafiltration effluent. However, with the continuous operation of the NF / RO membrane, more and more pollutants are accumulated on the surface of the NF / RO membrane. The effluent water quality deteriorates. Therefore, during the operation of the nanofiltration / reverse osmosis membrane, it must be cleaned regularly to maintain the designed operating pressure and water yield. [0003] The existing NF / RO membrane cleaning methods are divided into two categories: physical cleaning and chemical cleaning....

AI Technical Summary

Problems solved by technology

The disadvantage of this cleaning method is that the composition of the alkaline cleaning agent used is too complex, resulting in high cleaning costs, and the alkaline cleaning agent contains organic silicon, which cannot be used to clean nanofiltration / reverse osmosis membranes, because silicon Substances entering the membrane element will cause damage to the membrane, thereby affecting the service life and filtration effect of the membrane; at the same time, this cleaning method does not consider the influence of cleaning temperature, pH, and soaking time on the reverse osmosis membrane material during the cleaning process, and these factors It is very easy to cause irreversible damage to the nanofiltration / reverse osmosis membrane, which will seriously reduce the service life and filtration effect of the nanofiltration / reverse osmosis membrane

However, the existing chemical cleaning agents are general applicable cleaning agents, which are not highly targeted and difficult to effectively remove the pollutants on the surface of the NF / RO membrane, which cannot meet the cleaning requirements of the NF / RO membrane, and the chemical properties of the existing NF / RO membrane The cleaning method is relatively simple, and there are neglects in the cleaning sequence and cleaning parameter control. When used to clean NF / RO membranes for landfill leachate, the cleaning effect is often not good

In addition, nanofiltration and reverse osmosis membrane materials are polyamide materials, which are not strong in acid and alkali resistance, and will chemically react with strong alkali and oxidizing substances at a certain cleaning temperature. Factors such as cleaning temperature, pH, and soaking time are very sensitive. If the composition of the cleaning solution or the parameters during the cleaning process are not properly controlled, membrane damage will easily occur after multiple cleanings, resulting in poor water discharge effect.

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