Salinity wastewater zero-discharging method and system

Abstract

The invention relates to a salinity wastewater zero-discharging method and system. The method comprises the following steps: further hardness and silicon removal treatment is performed on suspension-removed degummed body by adopting a lime-sodium carbonate softening method and dissolved gas flotation filtration; the hardness is removed deeply through ion exchange; deep treatment is performed by adopting RO concentrated water; COD and NO3- are further reduced by adopting an advanced oxidation and hypersaline microorganism combination technology; an NF membrane salt separation process is adopted; multi-effect Mechanical Vapor Recompression (MVR) is adopted to perform a constant-temperature evaporative crystallization process to concentrate and separate salt; before MVR drained concentrated water is put into catalytic oxidation or an NF membrane, or all is put into carnallite MVR, carnallite is generated; a mother liquor of an MVR device is discharged, and enters a low-temperature refrigeration method to product a large amount of mirabilite to eliminate COD interference; a refrigerating fluid is subjected to advanced oxidization to eliminate COD in a discharged mother liquor outside acrystallization device. A pretreatment technology of the salinity wastewater zero-discharging method is efficient and stable; membrane concentration pretreatment, NF membrane salt pre-separation andreverse osmosis membrane concentration technologies are energy-saving and reliable; total product water and the finished product salt yield are high; the pretreatment technology is an energy-saving technology for reducing the carnallite yield.

Description

Technical field [0001] The invention belongs to the technical field of water treatment, and specifically relates to a zero-discharge method and system for salty wastewater. Background technique [0002] In the existing technology, the zero-discharge treatment scheme for salty wastewater has the following technical determinations: [0003] 1) High salt concentration after membrane concentration leads to COD, TN, and NH 3 Other indicators also rise at the same time, and cannot be further degraded. Especially after COD is concentrated, there is no effective removal, resulting in the evaporator crystallization COD value being too high and crystals unable to be obtained. [0004] 2) The salt separation process generally uses NF membrane to separate salt, and evaporation heat method is also used to separate salt. It is difficult to obtain industrial grade products with purity. [0005] 3) The system process is long, especially in order to increase the output rate of sodium sulfa...

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Problems solved by technology

[0005] 3) The system process is relatively long, especially in order to increase the output rate of sodium sulfate, it needs to be completed in combination with the freezing crystallization process, the degree of automation is the highest, and the energy consumption is high

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