The treatment technology of evaporator for high-salinity wastewater has been studied for decades at home and abroad. At present, the commonly used methods include biological method, SBR method and three-effect evaporator desalination method.
Biological treatment is one of the most commonly used methods in wastewater treatment at present, which has the characteristics of wide applicability and strong adaptability. Chemical waste water, such as dyes, pesticides, pharmaceutical intermediates and other high-salinity waste water evaporators, is seriously polluted and must be treated before being discharged. Moreover, the composition of this kind of wastewater is complex and has no recovery value, and the cost of other treatment methods is high, so biological treatment is still the first choice. Inorganic salts play an important role in promoting enzyme reaction, maintaining membrane balance and regulating osmotic pressure during microbial growth. However, if the salt concentration is too high, it will inhibit the growth of microorganisms. The main reasons are:
(1) When the salt concentration is too high, the osmotic pressure is high, resulting in microbial cell dehydration and cytoplasmic separation;
(2) In the case of high salt content, the dehydrogenase activity decreases due to salting out;
(3) High chloride ion concentration is toxic to bacteria;
(4) With the increase of sewage density, activated sludge is easy to float and lose.
There are many structural types of high-salinity wastewater evaporator, but no matter which type, refrigerant steam must be used in the design and manufacturing process to enable it to quickly leave the heat transfer surface and effectively maintain its reasonable liquid level.
The evaporator of high salinity wastewater effectively utilizes its heat transfer surface. When the refrigerant liquid of the equipment is throttled, a small amount of gas will be generated. In this way, steam can be effectively separated from the liquid through gas-liquid separation equipment, and only the separated steam can be sent to the evaporator to absorb heat, thus improving the heat transfer effect of the equipment.
If the liquid in the high-salinity wastewater evaporator can be vaporized and boiled on the wetted heating surface, the root of the steam bubble of the equipment will become smaller, the volume of the bubble will become smaller, and the bubble will easily leave its heating surface and rise. If the liquid cannot be wetted, the wet heating surface will evaporate and boil, thus forming a large number of vapor bubbles.
