A method of using struvite to remove ammonia and recycle gypsum at the same time

A struvite and gypsum technology, applied in chemical instruments and methods, flocculation/sedimentation water/sewage treatment, water/sludge/sewage treatment, etc., can solve the problems of large NaOH consumption and long decomposition time, and achieve treatment The effect of low cost, stable ammonia nitrogen concentration and low project investment cost

Active Publication Date: 2020-02-11
DONGGUAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] The object of the present invention is to overcome existing struvite recycling method to easily produce by-product Mg 2 P 2 o 7 And the decomposition time is too long, and there are defects or deficiencies in the large consumption of NaOH at the same time, providing a method for using struvite to remove ammonia and recover gypsum at the same time

Method used

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  • A method of using struvite to remove ammonia and recycle gypsum at the same time

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Effect test

Embodiment 1

[0046] This embodiment provides a method for utilizing struvite to remove ammonia and recycle gypsum at the same time, such as figure 1 , including the following steps.

[0047] a. Calcium hydroxide and struvite are added into the decomposition reaction tank 1 at a Ca:P molar ratio of 0.75:1, then clean water is added at a solid-liquid volume ratio of 1:10, and the stirring device in the reaction tank is started to make the reaction The mixture is fully mixed, and at the same time, the heating device in the reaction tank is turned on, so that the aqueous solution therein is completely evaporated to dryness. The steam and ammonia evaporated in the reaction tank enter the ammonia recovery device 6 from the gas outlet of the reaction tank to be recovered as ammonia water.

[0048] b. Transfer the reacted solid remaining in the decomposition reaction tank 1 to the dissolving tank 2, then add clean water according to the solid-liquid volume ratio of 1:3, start the stirring device ...

Embodiment 2

[0053] This embodiment provides a method for using struvite to remove ammonia and recycle gypsum at the same time, including the following steps.

[0054] a. Calcium hydroxide and struvite are added into the decomposition reaction tank 1 at a Ca:P molar ratio of 1:1, then clean water is added at a solid-liquid volume ratio of 1:15, and the stirring device in the reaction tank is started to make the reaction The mixture is fully mixed, and at the same time, the heating device in the reaction tank is turned on, so that the aqueous solution therein is completely evaporated to dryness. The steam and ammonia evaporated in the reaction tank enter the ammonia recovery device 6 from the gas outlet of the reaction tank to be recovered as ammonia water.

[0055] b. Transfer the reacted solid remaining in the decomposition reaction tank 1 to the dissolving tank 2, then add clean water according to the solid-liquid volume ratio of 1:8, start the stirring device in the dissolving tank, ful...

Embodiment 3

[0060] This embodiment provides a method for using struvite to remove ammonia and recycle gypsum at the same time, including the following steps.

[0061] a. Calcium hydroxide and struvite are added into the decomposition reaction tank 1 at a Ca:P molar ratio of 3:1, then clean water is added at a solid-liquid volume ratio of 1:15, and the stirring device in the reaction tank is started to make the reaction The mixture is fully mixed, and at the same time, the heating device in the reaction tank is turned on, so that the aqueous solution therein is completely evaporated to dryness. The steam and ammonia evaporated in the reaction tank enter the ammonia recovery device 6 from the gas outlet of the reaction tank to be recovered as ammonia water.

[0062] b. Transfer the reacted solid remaining in the decomposition reaction tank 1 to the dissolving tank 2, then add clean water according to the solid-liquid volume ratio of 1:10, start the stirring device in the dissolving tank, fu...

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Abstract

The invention relates to a method for circularly removing ammonia and recycling gypsum by using struvite. The method comprises the following steps: S1: dissolving calcium hydroxide and struvite in water, and stirring while heating until water is all evaporated, to obtain solid; S2: dissolving the solid in water, stirring and adding sulfuric acid to obtain a solid-liquid mixture; S3: separating the solid-liquid mixture; taking the supernate and adding into ammonia-nitrogen wastewater for treatment; performing solid-liquid separation, and cleaning to obtain solid which is gypsum; S4: adding ammonia-nitrogen wastewater into the supernate after the solid-liquid separation in S3, and stirring; adding magnesium oxide; standing for solid-liquid separation to obtain solid which is struvite, namely the source of struvite in S1; S5: repeating S1 to S4 for circular removal of ammonia as well as recovery of gypsum. By adopting the method provided by the invention in treatment of ammonia-nitrogen wastewater, the concentration of ammonia and nitrogen in the yielding water is stable, the removal rate of ammonia and nitrogen can reach 90% or more, and the concentration of phosphorous in the yielding water is less than 1mg / L; moreover, a high-purity gypsum product can be recycled.

Description

technical field [0001] The invention belongs to the technical field of environmental protection, and in particular relates to a method for using struvite to circulate ammonia and recover gypsum at the same time. Background technique [0002] At present, an important problem facing my country's water ecological environment protection is that the discharge of ammonia nitrogen far exceeds the environmental capacity of the receiving water body, and ammonia nitrogen has surpassed COD to become the primary pollutant affecting the environmental quality of my country's surface water. According to the 2013 "China Environmental Statistical Annual Report", the national discharge of ammonia nitrogen in wastewater reached 2.457 million tons, which is equivalent to nearly 8 times the environmental capacity of the receiving water body. Ammonia nitrogen (NH 3 and NH 4 + ) is a form of existence that has the greatest impact and harm on the aquatic ecological environment among various nitr...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C02F1/52C01F11/46C02F101/16
CPCC01F11/46C02F1/5254C02F2101/16C02F2301/043
Inventor 黄海明丁丽赵宁李晶
Owner DONGGUAN UNIV OF TECH
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