The reverse osmosis system pretreatment target is to remove the suspended solids and colloidal impurities in the raw water. When the water passes the treatment process of the reverse osmosis----5μm security filter, the effluent pollution index SDI on the rolled cellulose acetate The membrane and composite membrane are less than 4 and the hollow fiber aromatic polyamide membrane is less than 3.
In order to achieve this goal, the effluent quality of the clarifier and filter is as follows:
(1) The clarifier effluent turbidity is less than 1FTU, preferably less than 0.5FTU
(2) The effluent turbidity of the filter is less than 0.5 FTU, the CODMn is less than 1.5 mg/L, and the iron content is less than 0.05 mg/L (expressed as Fe).
In general, if the filtered water flows through a 5 μm security filter and the effluent still fails to meet its SDI requirements, an additional treatment process should be considered based on the specific circumstances. If the iron content is too high, the iron removal process is considered in the pretreatment.
On the other hand, in order to prevent the concentration of some insoluble salts on the membrane surface due to the concentration of water in the RO system, it is necessary to perform chemical dosing treatment, and it is generally recommended to add the reverse osmosis antiscalant.
In order to achieve this goal, the effluent quality of the clarifier and filter is as follows:
(1) The clarifier effluent turbidity is less than 1FTU, preferably less than 0.5FTU
(2) The effluent turbidity of the filter is less than 0.5 FTU, the CODMn is less than 1.5 mg/L, and the iron content is less than 0.05 mg/L (expressed as Fe).
In general, if the filtered water flows through a 5 μm security filter and the effluent still fails to meet its SDI requirements, an additional treatment process should be considered based on the specific circumstances. If the iron content is too high, the iron removal process is considered in the pretreatment.
On the other hand, in order to prevent the concentration of some insoluble salts on the membrane surface due to the concentration of water in the RO system, it is necessary to perform chemical dosing treatment, and it is generally recommended to add the reverse osmosis antiscalant.
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