Removal of chlorides from raw water
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Recently, as part of the water quality assessment for the project, it was found that the chloride levels in the water at the site selected were significantly above the acceptable limits. I searched online, and membrane treatment or nanofiltration is used to remove chlorides. However, for an industrial plant, the volume of water in circulation is very large, so this is clearly not an effective approach. Therefore, I would like to ask if there are any suitable new technologies?
The only methods for removing ions are reverse osmosis or ion exchange; nanofiltration does not yield very good results. If large water volumes are a concern, it is recommended to use reverse osmosis treatment on part of the water, mix it with the treated raw water, and then reintroduce it into the circulating water system.
What you’re saying is similar to another post from a few days ago – why are the chloride levels in water sources so high these days? Is it because of higher requirements? The author is discussing how to choose cost-effective technologies for removing chloride ions; both RO and ion exchange are well-established methods, with RO being considered a relatively new technology. The treatment scale can be calculated based on the chloride content in your raw water, the required value, and the water volume.
Nanofiltration cannot remove chloride ions; it’s reverse osmosis, right?
Nanofiltration can remove chloride ions, although the removal rate is low. It is recommended to use reverse osmosis for large water volumes.
Reverse osmosis is used, and the circulating water is replenished with water treated by reverse osmosis; it’s quite wasteful, as this water is usually used for boiler make-up water.
What is the chloride ion concentration? If it’s high, evaporation concentration is even better than nanofiltration; the costs are likely to be similar. However, if the chloride ion concentration is not much higher than the emission standards, it is also possible to dilute the emissions. The method mentioned earlier involves using a large amount of water, so diluting the emissions is a simpler solution.
I’m not an expert in this field; when I ask questions, I may not provide a complete description, but I’ve received a lot of guidance from many experts. Thank you.
It’s the urea cycle water, right? High levels of chloride ions in such water can cause corrosion of stainless steel equipment; moreover, the water contains a high amount of suspended solids, so ion exchange filters are suitable for use. Weak acid and strong acid resins should be used for the cation exchange beds, while weak base resins should be used for the anion exchange beds.
Our company has used nanofiltration membranes, which do not retain small molecules. At that time, the goal was to concentrate the organic components in the wastewater. The chloride ions in the concentrated solution were the same as those in the dilute solution; to remove these chloride ions, water had to be added to the concentrated solution multiple times to carry them out.
Dechlorination can be achieved through ion exchange, reverse osmosis, and electrodialysis