One sentence core: choose the right model, do a good job in preprocessing, control the concentration factor reasonably, and ensure stable and reliable reduction effect; But it is not a universal wastewater treatment device, and some waste liquids are strictly prohibited from entering the machine directly.

1、 Is the reduction effect reliable or not?

Low temperature evaporator is a physical negative pressure concentration, theoretically relying on water phase change separation.

Conventional stable water quality (electroplating cleaning concentrated water, RO high salt concentrated water, cutting waste liquid without a large amount of foaming agent): the reduction rate is generally 75% to 90%, and the working condition control can reach over 90%;

Emulsions containing surfactants and emulsifiers: prone to foaming and material leakage, blindly increasing the concentration ratio may result in a discount in actual reduction, and generally remain stable at 70% to 85%;   ⚠️ Key premise (whether the decision is reliable or not):

We must conduct continuous small-scale tests using water samples from our factory, and do not rely solely on the 95% limit value on the promotional page;

Cannot be super concentrated, the concentrated liquid needs to be drained when it reaches saturation crystallization and high viscosity range;

Supporting pre-treatment (sedimentation, filtration, oil separation), defoaming, and efficient foam removal;

The material matches the water quality to avoid corrosion and leakage.

Essence: It is a hazardous waste reduction device, not a wastewater standard discharge device. Moisture becomes condensed water, and all pollutants remain in the concentrated solution. The concentrated solution still belongs to hazardous waste and needs to be disposed of by qualified units.

2、 Waste liquid suitable for entering low-temperature evaporators

✅ Machining cutting emulsion waste liquid, grinding fluid ✅ Electroplating cleaning wastewater, heavy metal concentrate containing copper/nickel/zinc (excluding mercury) ✅ RO reverse osmosis concentrated water and high salt cleaning wastewater ✅ Coating spray wastewater and a small amount of ink cleaning waste liquid ✅ Laboratory inorganic high salt waste liquid

3、 It is not recommended/strictly prohibited to enter the waste liquid of the low-temperature evaporator (emphasis)

❌  Category 1: Contains volatile heavy metals (strictly prohibited from entering)

Mercury containing waste liquid and organic mercury; Some arsenic containing volatile systems. Reason: At low temperatures, it will evaporate with the gas phase, penetrate the demister, exceed the limit of heavy metals in condensed water, and pose a pollution risk to the exhaust gas.

❌  Category 2: Strong oxidizing, explosive, and unstable system waste liquid

Waste liquid containing sodium hypochlorite, perchlorate, and strong oxidant

Risks of easily decomposed and explosive waste liquids containing nitro groups, peroxides, etc.: After negative pressure heating and concentration, the concentration increases, and there is a risk of decomposition and explosion.

❌  Category 3: Large amount of low boiling point organic solvent waste liquid

Waste liquid of high concentration organic solvents such as acetone, methanol, ethanol, dichloromethane, and ethyl ester. Risk: Solvent volatilization into the gas phase, accumulation in a sealed chamber, flammability and explosiveness, and extremely high cost of VOC treatment; Ordinary low-temperature evaporators without explosion-proof structures are not suitable.

A small amount of solvent carryover, low concentration can be evaluated+explosion-proof modification+activated carbon adsorption, high concentration can be directly eliminated.

❌  Category 4: Strong concentrated acid and concentrated alkali solution

Concentrated hydrochloric acid, concentrated nitric acid, and concentrated strong alkali solution. Risk: Strong corrosion, even titanium materials have a tolerance limit; A large amount of acid mist evaporates, corroding the entire machine, damaging the vacuum pump, and making it difficult to treat the exhaust gas.

After diluting and adjusting the pH to the neutral range, evaluate whether it can proceed.

❌  Category 5: Waste liquid containing a large amount of fibers, colloids, and sludge residue

Sludge concentrate, large amount of suspended flocs, and fiber residue. Risk: Rapid blockage of heat exchangers, pump bodies, and pipelines, frequent shutdowns, and equipment wear and tear.

It needs to be precipitated and filtered first, and then the supernatant enters the evaporator.

❌  Category 6: Waste liquids containing resins, monomers, and easily polymerized and solidified materials

Partial adhesive waste liquid and unsaturated resin waste liquid. Risk: After concentration, the heat causes polymerization, sticking to the heat exchange surface, making it difficult to clean and directly scrapping the heat exchange components.

❌  Addendum: Contains a large amount of silica sol and high silica waste liquid

It is prone to form hard silicon scale, which is difficult to remove with conventional acid and alkali washing, and the heat exchange surface quickly fails. Try to avoid it as much as possible.

4、 Summary of Quick Avoiding Pits

Reduction depends not on reliability, not on the equipment itself, but on water quality, pretreatment, and concentration control; Most of the available materials are high salt, heavy metal inorganic waste liquids, and emulsified cutting waste liquids; The core red line that cannot be entered: volatile mercury, high concentration organic solvents, strong oxidants, explosive materials, and easily polymerized and solidified materials.