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CLEANING METHODS
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The membrane can be polluted and blocked up because the separation substance and impurity can deposit on the surface of the membrane in the process of UF, so the UF system must contains the process of cleaning membrane, the effective cleaning is the important ways and means to extend the using life .the cleaning methods include chemical cleaning and physical cleaning: |
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Balanced pressure cleaning method |
| Close the value of UF water, open the outlet valve of concentration water, wash the surface of membrane by raising flow speed. It can eliminate most of the swampy impurity on the surface of membrane. | |
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Ultra water cleaning method |
| The solution ability of ultra water is strengthen, the loose filth on the surface of the membrane can be cleaned with UF water first, and then cleaned with cyclic pure water. | |
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Back wash cleaning method |
| The cleaning water comes into membrane from the outlet of product water and permeat membrane, flow to outlet of concentration water. It can eliminate the mulch effectively. But it must be prevented from excess pressure to avoid destroying membrane and sealed adhesive point. | |
| （二）Chemical cleaning is a cleaning membrane method of chemical medicine and impuity in the surface of membrane reacting in each other. |
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Acid-solution cleaning |
| Chlorhydric acid, citric acid, oxalic acid can be used as usual agent, the PH value of acid-solution is 2 to 3 cyclic cleaning or cyclic cleaning after soaked 0.5h to 1h can eliminate inorganic impurity effectively. | |
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Alkali solution cleaning |
The main agent is NaOH, the PH value of solution is about 10 to 12, cyclic cleaning or cyclic cleaning after soaked 0.5h to 1h can eliminate impurity and grease effectively.
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Oxide cleaning agent |
| Cleaning UF membrane with the water solution of 1%-3% H2O2, 50-500mg/h NaClO can eliminate faith, bacterium. H2O2 and NaClO is the common germicide. | |
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Containing enzyme detergent
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| 0.5%-1.5% pepsin and trypsin can eliminate protein, polysaccharide, grease effectively. | |
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The puinciple of selecting chemical medicine as below：
1、The chemical medicine so mustn’t react on membrane and the other material of module.
2、The selected medicine mustn’t pollute secondary.
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