In the field of industrial wastewater treatment, low-temperature evaporators have become a key equipment for solving difficult wastewater treatment problems due to their core advantages of "low-temperature operation, efficient separation, and controllable energy consumption". However, not all industrial wastewater is suitable for low-temperature evaporators. If the wrong treatment equipment is selected, it will not only increase operating costs, but may also lead to problems such as substandard treatment effects and frequent equipment failures. Among them, high salt industrial wastewater, high COD recalcitrant industrial wastewater, and industrial wastewater containing toxic and harmful components are the main application scenarios that are highly compatible with the treatment characteristics of low-temperature evaporators. The following is a detailed analysis.

The first type is high salt industrial wastewater, whose core pain point is high salt content (usually exceeding 5%), which conventional biochemical treatment processes cannot withstand - high concentrations of salt can damage the structure of microbial cells, leading to the collapse of the biochemical system, and traditional evaporation equipment is prone to salt scaling and blockage due to high temperatures. A low-temperature evaporator can precisely solve this contradiction: it lowers the boiling point of water to 40-70 ℃ through a negative pressure environment, achieving water evaporation at low temperatures, avoiding the change in crystal form of salts (such as sodium chloride, sodium sulfate, etc.) at high temperatures, and reducing the risk of scaling; At the same time, during the evaporation process, water and salts are efficiently separated, and the resulting fresh water can be reused or discharged in compliance with standards. The concentrated high salt solution can be converted into solid salt through subsequent crystallization processes, achieving "reduction and resource utilization". This type of wastewater is commonly found in scenarios such as reactor wastewater in the chemical industry, concentrated saltwater produced by seawater desalination, and acid pickling and phosphating wastewater in metal surface treatment. For example, when a chemical enterprise treated reaction wastewater with a salt content of 8%, the salt recovery rate reached over 95% after using a low-temperature evaporator, and the freshwater reuse rate exceeded 80%, completely solving the problem of previous biochemical treatment failure.

The second type is high COD refractory industrial wastewater, which is characterized by high organic matter concentration (COD value often exceeds 5000mg/L) and poor biodegradability (B/C ratio below 0.3), such as intermediate synthesis wastewater in the pesticide industry, dyeing wastewater in the dye industry, resin wastewater in the coating industry, etc. Conventional treatment processes such as oxidation and adsorption either have high treatment costs or are difficult to reduce COD to emission standards. The advantage of low-temperature evaporator lies in "concentration first, then reduction": it reduces the volume of wastewater to 10% -20% of the original volume through low-temperature evaporation, greatly reducing the load of subsequent deep treatment - the concentrated high COD waste liquid can be centrally treated through incineration, advanced oxidation and other processes, which can reduce the amount of chemicals used and improve treatment efficiency; The COD value of fresh water produced by evaporation is extremely low (usually below 100mg/L), and can be discharged in compliance with standards through simple filtration. Taking a certain dye factory as an example, the COD value of its wastewater is as high as 12000mg/L. Directly using advanced oxidation treatment requires a large amount of oxidant, and the cost is high. After using a low-temperature evaporator for concentration, only the concentrated solution needs to be treated, reducing the amount of oxidant by 70% and the comprehensive treatment cost by 40%.

The third type is industrial wastewater containing toxic and harmful components, which contains heavy metals (such as chromium, nickel, lead), volatile organic compounds (VOCs), toxic agents (such as cyanide, fluoride), etc. If not treated properly, it can cause serious pollution to soil and water bodies, and even endanger human health. The closed operation characteristics of low-temperature evaporators can effectively prevent the diffusion of toxic substances: on the one hand, the negative pressure low-temperature environment reduces the volatilization of VOCs and avoids exhaust gas pollution; On the other hand, toxic substances such as heavy metals, due to their high boiling points, will all remain in the concentrated solution and will not enter the condensed water with water vapor, ensuring the safety of fresh water. This type of wastewater is typically used for chromium containing wastewater in the electronic electroplating industry, fluorine-containing wastewater in the semiconductor industry, and toxic organic wastewater in the medical chemical industry. For example, when a certain electroplating plant is treating nickel containing wastewater, a low-temperature evaporator is used to increase the concentration of nickel ions in the concentrated solution to over 5000mg/L, which facilitates subsequent chemical precipitation recovery. The concentration of nickel ions in the condensed water is less than 0.1mg/L, far below the discharge standard.

It should be noted that although the low-temperature evaporator has strong adaptability to these three types of wastewater, it still needs to be customized according to the specific indicators of the wastewater (such as salt type, COD composition, toxic substance concentration) in practical applications. For example, when treating wastewater containing easily crystallized salts, a forced circulation system needs to be used; When treating wastewater containing high viscosity organic compounds, it is necessary to optimize the heating method. If blindly selected, problems such as equipment blockage and unstable operation may occur. Therefore, before determining the treatment plan, it is recommended to conduct small-scale experiments on the wastewater to verify the treatment effect of the low-temperature evaporator, ensure accurate matching between the equipment and the characteristics of the wastewater, and truly leverage its efficient and energy-saving treatment advantages.