Brief description of zero-discharge treatment process for high-salt wastewater-Hezhong Environment (Beijing) Co., Ltd. was established in 2003

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Brief description of zero-discharge treatment process for high-salt wastewater

Published Time:

2021-04-21

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High-salinity wastewater refers to Wastewater with a mass fraction of total dissolved solids and organic matter greater than or equal to 3.5% 。 Wastewater sources are widespread, involving Coal chemical industry, Chemical industry, petroleum, Power, Mining, metallurgy, Papermaking and other processing stages. The wastewater discharge is large, containing a large amount of calcium, sodium, chlorine, sulfate and other organic ions.

High-salinity wastewater treatment processes generally adopt pre-treatment - Concentration - Evaporation crystallization methods. Different pretreatment processes, equipment, and evaporation concentration crystallization processes are selected based on the specific water volume, water quality, effluent requirements, investment, operating costs, and technical concepts. The following techniques are summarized.

1, Traditional pharmaceutical pretreatment processes such as coagulation, flotation, and sedimentation Processes

High-salinity wastewater treatment enters the evaporation concentration crystallization system through processes such as adjustment, chemical addition, flocculation, flotation, and sedimentation. This method has low investment and operating costs, but it has a certain impact on the quality of crystallized salt , making it difficult to sell.

2, Double-membrane pretreatment process

The advantage of desalination using the double-membrane method is that it significantly reduces the amount of water for evaporation crystallization thereby reducing the operating costs and investment of evaporation crystallization However, membrane 。 components require frequent chemical cleaning , and their service life is limited, resulting in high operating costs. 3,

Ozone/catalytic/condensation pretreatment process Using ozone as a strong oxidant and composite catalyst

etc. Under special conditions, they can fully react together, breaking the ring chains and long chains in the wastewater, and improving the biodegradability of high-salinity wastewater. 4,

Evaporation crystallization process For salt-containing solutions, there are two methods for crystallization. One is for target systems where solubility does not change much with temperature,

it is possible to use the method of evaporating the solvent ; the other is for systems where solubility changes significantly with temperature, the method of ， to use the method of evaporating the solvent or cooling the solution can be used. High-salinity wastewater is usually composed of a mixture of various salts. Due to the common ion effect, the

solubility curve and boiling point of the solution are different from those of a single system, generally its saturation solubility is lower than chemical cleaning that of a single system, and the boiling point is higher than solubility is that of a single system at the same concentration. To accurately determine the solubility and boiling point of multi-component salt water, experimental research must be carried out. This is the key to the design of the evaporation crystallization process. 工艺设计的关键。