1. Core treatment effect: High efficiency in water-salt separation, strong compliance with standards

The low-temperature evaporation equipment achieves wastewater evaporation through "vacuum boiling point reduction" (typically at 40-70℃). The water vapor can be condensed and recycled into fresh water, while the remaining high-concentration salt is discharged in the form of crystals or concentrated slurry. Its core indicators perform excellently:

Salinity removal rate: For high-salt wastewater (such as desulfurization wastewater and reverse osmosis concentrate) with a salt content of 10%-30%, the salinity removal rate can generally reach over 95%. Some equipment, combined with forced circulation or crystallizer design, can achieve "near-zero emission" of salt (freshwater recovery rate ≥ 85%, concentrated salt slurry moisture content ≤ 50%), meeting the requirements of the Integrated Wastewater Discharge Standard (GB 8978-1996) or circulating water reuse.

Fresh water quality: The turbidity of recycled fresh water is usually less than 5 NTU, and the TDS (total dissolved solids) can be controlled below 100 mg/L (depending on the pretreatment process). It can be directly used for workshop flushing, circulating cooling water replenishment, etc., reducing fresh water consumption.

Crystal purity: If the wastewater composition is simple (such as containing only NaCl and Na₂SO₄), by optimizing evaporation temperature and stirring parameters, the purity of the discharged salt crystals can reach 90%-98%. In some scenarios, "salt resource recovery" can be achieved (such as the reuse of by-product salt in the chemical industry).

II. Wide range of applicable scenarios: obvious advantages in dealing with complex high-salt wastewater

Compared to traditional evaporation processes (such as multi-effect evaporation and MVR), low-temperature evaporation equipment exhibits stronger adaptability to the components of wastewater, making it particularly suitable for the following challenging scenarios:

High-salt + thermally sensitive wastewater: such as fermentation concentrated wastewater in the biopharmaceutical industry and food processing wastewater. In low-temperature environments, the denaturation of proteins, polysaccharides, and other substances can be avoided, reducing secondary odors (such as ammonia and hydrogen sulfide) produced by the decomposition of pollutants.

High-salt + high-COD wastewater: Such as pesticide wastewater and dye wastewater in chemical industrial parks, some low-temperature equipment (such as low-temperature vacuum evaporators) can use the physical process of "evaporation + condensation" to first separate out fresh water, and then perform subsequent incineration or solidification treatment on the concentrated liquid (high-COD, high-salt), reducing the overall treatment cost.

Small batch/decentralized high-salt wastewater: such as mine water from remote mining areas and wastewater from small electroplating plants, low-temperature evaporation equipment is mostly modularized design (single unit processing capacity of 0.5-5m³/d), with a small footprint (about 5-10㎡), no need for complex civil engineering, short installation and commissioning period (1-2 weeks), suitable for "on-site treatment" in decentralized scenarios.

III. Limitations to be noted: not all high-salt wastewater is applicable

The treatment effect of low-temperature evaporation equipment is also constrained by the characteristics of wastewater. Careful selection is required in the following scenarios:

Wastewater containing high-boiling organic compounds: If the wastewater contains substances with boiling points higher than 100°C, such as paraffin and heavy oil, these substances are difficult to evaporate during low-temperature evaporation and will gradually adhere to the surface of the evaporator heating tube, leading to a decrease in heat transfer efficiency (commonly known as "scaling"). This requires frequent shutdowns for cleaning, affecting operational stability.

Wastewater containing volatile toxic substances: such as high-salt wastewater containing volatile organic compounds (VOCs) like chloroform and methanol, during low-temperature evaporation, VOCs will enter the condensation system along with water vapor, resulting in contamination of the recovered fresh water. Additional VOCs removal units such as activated carbon adsorption and membrane separation are required, increasing equipment investment.

High-salt + high-hardness wastewater: such as groundwater concentrate containing a large amount of Ca²⁺ and Mg²⁺, which is prone to generating precipitates such as CaCO₃ and Mg (OH)₂ during low-temperature evaporation. It is necessary to perform pretreatment through "dosing softening + filtration" in advance, otherwise it will block the evaporator flow channels and, in severe cases, lead to equipment scrapping.

IV. Practical case reference: Effect verification in industrial scenarios

Taking the treatment of high-salt wastewater containing nickel from a certain electroplating factory as an example (wastewater quality: salt content 22%, Ni²⁺ concentration 80mg/L, COD 500mg/L), the process of "low-temperature vacuum evaporator (treatment capacity 2m³/d) + pretreatment (pH adjustment + heavy metal capture)" was adopted, and the treatment effect is as follows:

Fresh water effluent: TDS 85mg/L, Ni²⁺ concentration <0.1mg/L, COD 35mg/L, meeting the reuse standards for the electroplating industry (GB/T 21966-2008), with a reuse rate of 82%.

Concentrated salt slurry: With a moisture content of 45%, it forms a dry salt cake after pressure filtration and is then disposed of by a hazardous waste disposal unit. Compared to directly discharging the original wastewater, the amount of hazardous waste is reduced by 75%, and the annual disposal cost is reduced by approximately 120,000 yuan.

Summary:

The core advantages of low-temperature evaporation equipment in treating high-salt wastewater lie in its "high-efficiency separation, low-temperature protection, and modularity". It is particularly suitable for small batches of high-salt wastewater with complex components (heat-sensitive, high COD), achieving remarkable results in water recovery and reduction. However, pretreatment design must be tailored according to the specific composition of the wastewater (such as the presence of high-boiling-point substances or high-hardness ions) to prevent issues like scaling and blockage that could affect operational efficiency. When selecting equipment, it is recommended to first conduct pilot tests (by sampling wastewater and verifying separation efficiency on laboratory equipment) to determine process feasibility, before proceeding with the procurement of industrial equipment.