Sodium sulfate crystals in wastewater

Unlike sodium chloride, its solubility in water is greatly affected by temperature, and the pattern of these changes is quite unusual. Its weight percent concentration varies with temperature as follows: 10, 20, 25, 30, 40, 50, 60, 70, 80, 90, 100, 8. 28 16. 13 21. 94 29. 22 32. 35 31. 35 30. 90 30. 39 30. 02 29. 70 29. 67 Therefore, the desired crystal must be concentrated to saturation at temperatures above 30 degrees before being cooled to below 20 degrees; ideally, below 15 degrees. This allows for the concentration of 2/3 of sodium sulfate (decahydrate). This type of smoke, whose solubility changes significantly with temperature, must be crystallized through a temperature difference. You have used three-effect evaporation, so the water production ratio will definitely not exceed 3; the energy consumption remains very high. We have developed a low-investment, energy-efficient thermally driven membrane process that can be used to concentrate highly saline aqueous solutions and recover high-quality fresh water. This process does not require high temperatures, high pressures, or negative pressure (or vacuum) to operate, and it is noise-free. If the temperature of the wastewater is below 40 degrees, a low-temperature heat source (60–120 degrees) can be used as a driving force; the efficiency of heat utilization in this case (with a water production ratio of 8–15) is much better than that of multi-stage flash evaporation and multi-effect evaporation. When the wastewater temperature is between 70–100 degrees, it is possible to recover more than 50% of the water without the need for an external heat source, while simultaneously concentrating the saltwater. The electrolyte concentration in the fresh water produced by this process can be as low as less than 1 ppm, with typical values ranging from 10 to 100 ppm. Another advantage of this process is that the equipment used is mostly made of plastic, which completely eliminates the problem of corrosion associated with multi-stage flash evaporation and multi-effect evaporation processes. The equipment required for this process is relatively compact, similar to that used in reverse osmosis; therefore, for a given separation task, the volume of equipment needed is much smaller than that required for multi-stage flash evaporation and multi-effect evaporation. As mentioned earlier, even in the absence of high temperature and pressure or negative pressure (or vacuum), the thermal efficiency of this process (water production ratio) is still better than that of multi-stage flash evaporation and multi-effect evaporation; it is 8 to 15 times higher than that of the membrane distillation process I developed 20 years ago. Furthermore, the investment in this process is also low. The total cost of this process (equipment depreciation, steam, electricity consumption, etc.) is 8–12 yuan per ton of water. Please calculate the total revenue (salt, desalinated water) and the net profit. If you are interested, feel free to contact me. My email addresses are: yqin@chembrane.com or yjqin1@yahoo.com. My email is yjqin1@yahoo.com, or yqin@chembrane.com

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