Electrodialysis or MVR?
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Wastewater medium: aqueous solutions of sodium sulfate, sodium fluoride, and sodium chloride, with a total volume of 700 cubic meters per day; the concentration of sodium sulfate is approximately 100 g/L, that of sodium fluoride is about 1.37 g/L, while the concentration of sodium chloride is slightly higher than that of sodium fluoride, but it remains low as well. The current situation is that the owner can provide only a limited amount of steam; if traditional multi-effect evaporation is used to remove all the water, it requires an excessive amount of steam. I’m looking for other approaches to reduce energy consumption. Considering both the initial investment and operating costs, it’s unclear which approach is better
If there is still COD in this system, then electrodialysis need not be considered
This requires a pilot test or pilot scale trial, along with a comprehensive evaluation. Given such a large volume of processing, issues such as processes, energy consumption, equipment, and operational control are involved, so it is impossible to draw conclusions based on mere speculation. What level of intelligence and mental arithmetic skills would be required to achieve that?
There is no COD; this is the solution obtained after the treatment of acid-producing wastewater
The total salt content is already over 10%; using ED, the maximum achievable level is around 18%. For safety reasons, the concentration of the liquid output should be around 15%, and further evaporation will be necessary thereafter. At this concentration, compared to the combination of ED and MVR evaporation, using full MVR evaporation might be better. The equipment investment costs should be roughly the same. The operating cost may be higher for MVR, while it is slightly lower for ED combined with MVR. In terms of stability and application scope, MVR is definitely more widespread.
MVR applications should be more widespread and stable. Moreover, there may be few modifications to the existing system. However, it’s best to conduct a small test to check conditions such as temperature rise and determine whether MVR is suitable.
Consider the MVR; with a capacity of 30 tons per hour, it can achieve the desired result in one go, although its operating costs may be higher than those of the ED+MVR combination.
The initial salt content is already quite high; MVR is still the more suitable option
The salt content is already quite high; in such cases, using MVR directly is the best option. If ED+MVR is used, as the concentration increases, additional steam will be required for preheating via MVR, which raises the operating costs of MVR. Reducing the amount of ED used doesn’t help much in terms of reducing concentration, and considering stability as well, it’s better to use MVR directly
With such high inlet TDS, when comparing concentration reduction and long-term system stability, ED is no longer advantageous
In areas where steam resources are relatively scarce, it is still appropriate to use MVR! The premise is the issue of temperature rise in the mixed salts; find an MVR manufacturer to conduct experiments for you!