High chlorate content?
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This post was last edited by sunjl1981 on 2013-1-6 at 21:43. Our company uses Wood’s electrolytic cells along with DuPont’s membranes. Recently, the dechlorination effect was poor, although all other parameters were normal; sodium sulfite was then added to remove free chlorine, but the cause of the problem was never identified. Now, there is a high level of chlorate – around 9.3 in the output from the electrolytic cells, around 8.2 in the cell used for chlorate decomposition, and around 8.0 in the dechlorinated brine. Adding acid did not bring any change either. Could everyone please help analyze this situation? Thank you! ， ， -
Due to the high content of chlorates, simply adding acid is not sufficient for decomposition; a temperature of over 95°C is required for this process. So the original poster still needs to get a chlorate decomposition device
We all have in use chlorate decomposition tanks
“The value from the electrolytic cell is around 9.3, that of the chlorate decomposition cell is around 8.2, and that of the dechlorinated brackish water is around 8.0 – all of these values are below 10. Check if there are any issues with the testing method. The chlorate level in our plant has always been in the 9s. In the end, it turned out that the value was in the 20s; it was a problem with the testing method – whenever the value exceeded 10, the result showed around 9.
It’s possible that the decomposition rate of your chlorate is too low; as mentioned above, it might be due to insufficient temperature, so you should check that. Should we also check the analysis methods?
Oh, a temperature of 90 degrees in the chlorate decomposition tank should work fine; after all, that temperature is always maintained around 90 degrees there
The aluminate decomposition tank is affected not only by temperature, but also by the amount of acid added and the flow rate of brackish water entering the tank! ! It’s usually a 1:10 ratio!
Yes, the HCl level in the decomposition tank is around 1.2. Another sample was prepared today: the chlorate concentration entering the electrolyzer was 6.01, while it was 9.36 upon exit; in the chlorate decomposition tank, it was 7.87. It seems that side reactions in the electrolyzer have increased! Please advise on what to do. Our electrolytic cells have been in use for one and a half years; should we not consider adding acid?
The efficiency of chlorate decomposition is too poor. Here, the temperature in the decomposition tank is controlled at 94 degrees; the ratio of brine to acid is about 10:1 (by volume). A tank with a capacity of 24 m3 can handle a flow rate of around 20 m3/h of brine, and the concentration at the outlet can be reduced to below 1 g/L. The inbound and outbound traffic on the upper floor increased by 3.3, which is indeed high.
Well, your decomposition efficiency is indeed good, but mine isn’t as good. At the same time, there are more inlets and outlets on my electrolyzer – what should I do?
If there is an increase in the number of inlet and outlet ports of the electrolyzer, acid addition must be carried out. However, the efficiency of your chlorate decomposition tank needs to be improved further. The residence time of the anode solution should be at least 1 hour, the temperature should be maintained between 90-95 degrees, and as much acid as possible should be used. If the amount of chlorate produced by the electrolyzer is balanced with that of the chlorate that gets decomposed, it may not be necessary to add acid to the electrolyzer for now; if this balance cannot be achieved, acid should be added as soon as possible