Evaporating and crystallizing zero-discharge treatment system and method for high-COD waste water

Abstract

The invention discloses an evaporating and crystallizing zero-discharge treatment system and method for high-COD waste water. The system comprises a preheater, an evaporator, a crystallizer, a centrifugal separator, a mother liquor tank and a quality adjusting unit, a water inlet and a water outlet of the preheater are connected with raw waste water and a water inlet of the evaporator respectively, concentrated liquor generated by evaporation of the evaporator enters the crystallizer, crystal slurry generated by the crystallizer enters the centrifugal separator, mother liquor generated by centrifugal separation of the centrifugal separator returns to the crystallizer, crystallized salt generated by separation is discharged or recycled, and the quality adjusting unit removes COD in the waste water through electrocatalytic oxidation and is arranged between the water outlet of the preheater and the water inlet of the evaporator, or between a concentrated liquor water outlet of the evaporator and a water inlet of the crystallizer or between a water outlet of the mother liquor tank and the water inlet of the crystallizer. The system can realize zero discharge truly under the premise of running stably for a long time.

Description

technical field [0001] The invention relates to a waste water treatment system and a treatment method, in particular to a waste water evaporation and crystallization zero discharge treatment system and treatment method capable of high COD, and belongs to the field of environmental protection water treatment. Background technique [0002] With the introduction of the concept of "zero discharge" in wastewater treatment, evaporation crystallization technology has been widely used in the field of saline wastewater treatment. At present, saline wastewater is mainly treated by the process of pretreatment + membrane concentration + evaporation and crystallization. As the terminal step of wastewater treatment, the evaporation crystallization step mainly adopts mechanical vapor recompression technology and multi-effect evaporation technology. [0003] The above-mentioned technologies have been applied in domestic wastewater treatment projects, and have a certain amount of engineerin...

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Problems solved by technology

[0003] The above-mentioned technologies have been applied in domestic wastewater treatment projects, and have a certain amount of engineering achievements in the treatment of high COD wastewater, but most of them have the following problems during operation: 1. There is a certain amount of high-concentration mother liquor discharged, and Real zero discharge cannot be achieved; 2. The organic content in the obtained crystalline salt is high and cannot be recycled and utilized; 3. The discharged mother liquor and high-COD crystalline salt are solid waste or hazardous waste and need to be further treated, which is difficult and expensive High; 4. The existing evaporative crystallizer is composed of a large number of heat exchange equipment. The existence and accumulation of organic matter in wastewater will reduce the heat exchange efficiency of heat exchange equipment and increase energy consumption; 5. The existence and accumulation of organic matter in wastewater will also reduce Increased difficulty of salt cleaning in crystallizers

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