Reduce the chlorate content in brackish water
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The Nakayama natural circulation electrolyzer used by our company is in its third year of operation this year. A few months ago, the chlorate content in the brackish water leaving the tank increased significantly, reaching up to about 30 g/L at its peak. To reduce the chlorate content in the system, I increased the acidity of the chlorate decomposition tank from ≥0.3 mol/L to ≥0.4, which reduced the amount of chlorate after decomposition from ≤3 g/L to around 1.1–1.3 g/L. Currently, the chlorate level in the system is about 6–7 g/L (with a level of ≤9 g/L in the effluent). As the acidity of the decomposition tank was increased, the pH value of the brackish water before entering the dechlorination tower (PH312) also decreased accordingly, and it is now around 1.1~1.3. I’d like to discuss with my colleagues whether there are any good methods to reduce chlorates
Your current method for reducing chlorates is already quite good; it keeps costs within acceptable levels and maintains the operating conditions within feasible bounds. As long as the chlorate concentration does not rise to the point of affecting electrolytic efficiency, that’s ideal. There’s no need to reduce it too much, as that would increase costs and cause difficulties in operation.
Reducing the pH value of the brine fed into the cell within the specified process parameters can minimize the occurrence of anodic side reactions, thereby reducing the formation of chlorates
That’s right; the acidity level in the tank is now close to 0.15
Hydrochloric acid is added to the brackish water tank (D-260), and chlorate is partially decomposed using the temperature of D-260 to carry out dechlorination.
Adding a chlorate decomposition device to reduce the level of chlorates in the system
The problem should be addressed at its root; personally, I think you should adopt the D170 acid treatment process.
Add reagents similar to ammonia drop by drop; this technology is available in China