Performance of fouling and film blocking by different pollutants
1. Carbonate scale
The performance after scaling: the standard permeate water flow rate decreased, or the desalination rate decreased.
Reason: the concentration polarization of membrane surface increases.
2. Fe / Mn
Performance after pollution: the standard pressure difference increase(mainly occurred in the membrane element at the front of the device), may also cause the decrease of water permeability. Usually manganese and iron are present at the same time.
If deposition occurs, it will first affect the membrane element at the end of the system with the highest salt concentration, showing that the pressure difference in the second stage increase significantly. Special cleaning agent is needed.
Particle silicon: fouling membrane element flow channel, resulting in the increase of system pressure difference. It is effective to use 0.4% dichloroamine to dissolve the seriously polluted silica scale.
Colloidal silicon: similar to particle silicon.
Dissolved silicon: form silicate precipitation, should use dichloroamine cleaning.
5. Suspended matter / organic matter
The performance of pollution and plugging: the water permeability decreased, and the pressure difference in the first section increased significantly. If the SDI of feed water is greater than 4 or the turbidity is greater than 1, the possibility of organic pollution is greater.
The performance of pollution and plugging: the standard pressure difference increases or the standard water permeability decreases. Non oxidizing fungicide and alkali can be used for cleaning.
7. Iron bacteria
The performance of pollution and plugging: the standard differential pressure increased. EDTA sodium salt and alkali can be used for cleaning.