Zero discharge industrial wastewater treatment

Technological process

1、Softening and sedimentation technology

Adopting measures such as internal circulation stirring reaction, mud and slag reflux, floc growth control technology, high efficiency precipitation technology, etc. to reduce calcium and magnesium hardness in concentrated brine, and at the same time to realize the removal of fluorine, silica, heavy metals, reduce alkalinity, and to improve the stability of the subsequent operation of the membrane concentration unit.

2、Softening membrane technology

Pre-treatment adopts the process of “sodium hydroxide + soda ash + magnesium salt (adjusted according to the silica content in the water to confirm the final dosage)”, which reduces the risk of system scaling and pollution. Softening system with the use of ultrafiltration membrane, filtration accuracy of 0.1 microns, after the filter can be directly into the membrane system, instead of the traditional coagulation and precipitation + filtration process, improve the quality of produced water, shorten the process.

3、 Catalytic oxidation technology

Ozone has a high oxidation potential, can oxidize and decompose most of the organic matter without introducing impurity ions, and the reaction product has no residue; catalyzed by the catalyst to improve the utilization rate of ozone and enhance the oxidation efficiency. Adopting ozone catalytic oxidation technology can remove the residual organic matter, reduce TOC and chromaticity of the water, ensure the quality and whiteness of the final crystalline salt, and at the same time significantly reduce the energy consumption of the treatment.

4、Concentrated brine electrolytic oxidation technology

A small amount of TOC remains in the secondary brine after pretreatment, which will affect the whiteness and quality of the by-product crystallized salt after evaporation and concentration if not treated. Aiming at the characteristics of high TDS and high current conversion efficiency in secondary brine, electrocatalytic oxidation technology is adopted to reduce TOC, which can significantly reduce the treatment cost.

5、Multi-effect evaporation and crystallization

Multi-effect evaporation system is composed of multiple single-effect evaporator system, the previous effect evaporates the secondary steam introduced into the next effect as heating steam, and so on in turn, only in the first effect to use the raw steam, the end of the effect produced by the condensation of the secondary steam as water. The use of multi-effect evaporation can make full use of thermal energy, that is, through the re-use of secondary steam in the evaporation process, reduce the consumption of raw steam, thus improving the economy of the evaporation system.

6、MVR evaporation crystallization

Mechanical Vapor Recompression (MVR) is a technology that reuses the energy of self-generated secondary vapors to reduce the demand for external energy. The secondary steam, compressed by the compressor, increases in pressure and temperature and enthalpy, and is sent to the heating chamber of the evaporator to be used as heating steam to maintain evaporation of the material, while the heating steam itself transfers the heat to the material and then condenses into water for reuse. In this way, the original steam to be discarded has been fully utilized, recovering latent heat and improving thermal efficiency.

7、Membrane salt separation and cryocrystallization technology

Nanofiltration salt separation and concentration to separate sodium sulfate from sodium chloride. Sodium sulfate + water is obtained by nitrate production (concentration) freezing + centrifugation.

Practical application

1、Pre-treatment + membrane + evaporation crystallization salt separation technology

Pre-treatment-membrane concentration-evaporation crystallization technology as the core of the near-zero-discharge treatment process:

(1) Follow the design concept of “high quality water, high use, low quality water, low use”;
(2) Improvement of reuse water quality, safeguarding of reuse safety, and broadening of reuse applications;
(3) Developing salt recovery process technologies for different industries and enterprises.

Coal mine mine water depth treatment project out of salt map

2、Ion resolution technology (application in power plant desulfurization wastewater)

Power plant desulfurization wastewater process:

Recommendation: Precipitation + High-efficiency purifier + Ion resolution + Evaporation crystallization
The fluctuation range of chlorine ion content in raw desulfurization wastewater is 10000~20000 mg/L;
Freshwater chloride 2500~3500 mg/L;
Chloride ion removal rate 75~85%;
Concentrated water chloride ion concentration range 90,000~100,000 mg/L;
Concentration multiplication rate 7.00~11.0 times;

3、Three-dimensional digitization technology

Advantages of 3D digitization technology in industrial wastewater large-scale projects: