Synthetic ammonia organic wastewater divalent salt recycling and zero discharge process

Abstract

The invention discloses a synthetic ammonia organic wastewater divalent salt recycling and zero discharge process which comprises the following steps: lifting pretreated effluent by a pump to enter reverse osmosis, conveying produced desalted water to a reuse water tank, conveying reverse osmosis concentrated water to a nanofiltration system, conveying nanofiltration produced water to a monovalent salt recycling system, conveying nanofiltration concentrated water to a divalent adjusting tank, enabling the nanofiltration concentrated water to enters a catalytic oxidation reaction device to be subjected to oxygenolysis after adjustment; carrying out electrodialysis for concentration, removing foreign ions by resin adsorption, and entering an evaporative crystallization device; preparing and obtaining a sodium sulfate product with the purity above 99%, centrifugally separating mother liquor to flow back to a nanofiltration system, conveying evaporation condensate to a recycling water tank, dissolving the sodium sulfate product to prepare a solution with a certain concentration to enter a bipolar membrane electrodialysis device so as to prepare an acid-base product. Through the combined process of pretreatment, reverse osmosis, nanofiltration, catalytic oxidation, electrodialysis and evaporative crystallization, and the reverse osmosis concentrated water of the wastewater, zero emission of the wastewater is realized in a real sense.

Description

technical field [0001] The invention relates to the technical field of industrial wastewater in the nitrogen fertilizer manufacturing industry, in particular to a divalent salt recycling and zero discharge process of synthetic ammonia organic wastewater. Background technique [0002] The conventional synthetic ammonia wastewater treatment and reuse process realizes the resource reuse of wastewater through the combined process of pretreatment-biochemical treatment-membrane concentration treatment (UF+RO), and obtains 60% to 80% of desalted water and 20% to 40% In the process of reverse osmosis concentrated brine, the reverse osmosis membrane intercepts the waste water salt, along with the waste water pollutants are intercepted and concentrated, and finally most of the salt and pollutants are enriched and concentrated in the reverse osmosis concentrated water; the concentrated water contains The salt content is generally above 10g / L, mainly containing Na + , Cl - , SO 4 2～...

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Problems solved by technology

[0002] The conventional synthetic ammonia wastewater treatment and reuse process realizes the resource reuse of wastewater through the combined process of pretreatment-biochemical treatment-membrane concentration treatment (UF+RO), and obtains 60% to 80% of desalted water and 20% to 40% In the process of reverse osmosis concentrated brine, the reverse osmosis membrane intercepts the waste water salt, along with the waste water pollutants are intercepted and concentrated, and finally most of the salt and pollutants are enriched and concentrated in the reverse osmosis concentrated water; the concentrated water contains The salt content is generally above 10g / L, mainly containing Na + , Cl - , SO 4 2～ Plasma, the Ca that makes up the hardness 2+ , Mg 2+ And carbonate ions and bicarbonate ions, the organic components in the pollutants are complex, containing a large number of heterocyclic and polycyclic organic compounds, the biodegradability is extremely poor, and the COD has reached 800mg / L-1200mg / L. Inappropriate, it is difficult to repair the damage to the surrounding ecological environment, which will also be a major problem that has plagued the entire industry and discussed research for a long time

[0003] In recent years, the country has increased the protection of the natural environment, and the discharge standards of pollutants have become more and more stringent. With the "Sodium Sulfate of Coal Chemical Industry By-Products" issued by the China Coal Processing and Utilization Association in 2019 - T / CCT001~2019 China Coal The physical and chemical indicators of sodium sulfate in the chemical by-product industry and the requirements for the physical and chemical indicators of sodium chloride in the coal chemical by-product industrial +reverse osmosis) and evaporative crystallization to treat reverse osmosis concentrated water. This process can only remove part of the colloid, suspended solids and calcium and magnesium ions, but most of the pollutants have not been removed, because the concentrated water produced by the membrane has a lot of High refractory COD and organic fouling will not only lead to frequent cleaning of the membrane, shorten the service life of the membrane, but also cause the TOC index of the evaporated and crystallized product salt to exceed the standard, and finally it can only be treated as hazardous waste, causing the entire Waste of Wastewater Zero Discharge Treatment Cost

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