When the reverse osmosis process operation of the five control elements
To ensure that the reverse osmosis treatment system normal, reliably, the need for process system operation under controlled conditions, specific control elements include the following aspects.
1, the pH value of the reverse osmosis membrane made of different materials with different pH value for fan & Chi;
, such as cellulose acetate membrane pH used van & Chi;
For 3 ~ 8, aromatic polyamide membrane pH van & Chi;
For 4 ~ 10;
Dupont nylon type hollow fiber membrane pH van & Chi;
5 ~ 12.
The use of slurry pH value beyond membrane qualified fan & Chi;
, it will have hydrolysis and aging and other harmful effects on membrane, cause water rate drop, causing membrane, the performance of a continuing decrease until the membrane damage.
Usually, cellulose acetate membrane runtime pH should be controlled between 4 ~ 7, and the pH of the aromatic polyamide membrane runtime should be controlled in 3 ~ 11, the pH of the composite film allows van & Chi;
About 2 ~ 11.
2, the temperature in the process of reverse osmosis, feed liquid temperature will be in accordance with the operation of improved.
In a fan & Chi;
, the temperature of feed liquid viscosity reducing, is beneficial to the increase of the reverse osmosis water rate, temperature usually?
On the membrane permeable ability generally marked goods membrane for temperature data values in 24 ~ 25 ℃, need through the working condition of correction coefficient calculated temperature actual permeable ability.
Should be paid attention to, the operating temperature shall not exceed the heat resistance of membrane, otherwise will affect the service life of the membrane.
3, pretreatment of dealing with the material liquid pH value, and contains the discretion of the suspended matter and microbe quantity and so on, will influence the effect of reverse osmosis, so need to take effective pretreatment of raw water when necessary measures, such as pH value control, filtration, disinfection, etc. , in order to give full play to the efficiency of reverse osmosis.
4, operating pressure in the process of reverse osmosis, maintain and improve the operating pressure is beneficial to increase the rate of water, and because the membrane is pressed, the transmittance of salt will decrease.
But operating pressure exceeds a certain limit, the membrane compaction deformation is severe, can lead to membrane and membrane permeable ability recession of aging.
, therefore, should be dealt with according to the actual material liquid and the selected pressure performance of reverse osmosis membrane, select the appropriate operating pressure.
5, membrane component cleaning effect of membrane fouling is inevitably have an impact in the operation of the reverse osmosis system normal operation.
Even before the operation to pretreatment of material liquid, also cannot completely eliminate the pollution of membrane, membrane pollution, light water rate and desalination rate decline, has great influence on the life of the membrane, and even cause paralysis treatment system running.
Therefore, we need to periodically according to the actual situation for cleaning membrane module.