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Struvite circulating crystallization method for treating synthetic ammonia wastewater

A technology for synthesizing ammonia and struvite, which is applied in chemical instruments and methods, biological organic part treatment, water/sewage multi-stage treatment, etc. The effect of reducing the cost of chemicals, reducing ammonia nitrogen pollutants, and reducing the concentration of phosphorus in effluent

Inactive Publication Date: 2012-02-01
TONGJI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] In order to achieve the above object, the present invention aims at the disadvantage of high cost of struvite crystallization, and alkali pyrolyzes the struvite solid harvested by precipitation to obtain a solid pyrolysis product containing only phosphate and magnesium salt, and simultaneously pyrolyzes The released ammonia nitrogen is absorbed with dilute hydrochloric acid or dilute sulfuric acid; the pyrolysis products containing phosphate and magnesium salt are used again to treat wastewater and obtain struvite, and this cycle is repeated several times to fully improve the utilization rate of phosphate and magnesium salt. Recycled struvite recycled as slow-release fertilizer

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] A. Collection of struvite. First

[0023] Determination of NH in synthetic ammonia wastewater 4 + -N concentration is 2065mg / L, COD is 648mg / L. Adjust the pH of the wastewater to about 9.0, and then add purchased industrial grade Na to the synthetic ammonia wastewater 2 HPO 4 21g / L and MgCl 2 15g / L, stirred for 20min, stood still for 10min after the reaction, harvested the solid precipitate as struvite, washed the struvite with deionized water 2 to 3 times, and air-dried for later use. After treatment, the residual ammonia nitrogen concentration of synthetic ammonia wastewater is 118mg / L, and the residual phosphorus concentration is 4.45mg / L, which meets the requirements of A / O process.

[0024] B, the struvite solid harvested in step A is pyrolyzed with alkali.

[0025] The struvite harvested in step A is pyrolyzed with alkali. The alkali is commercially available industrial-grade potassium hydroxide. The amount of alkali added is 0.23 times the mass of the str...

Embodiment 2

[0032] A. Collection of struvite. Determination of NH in synthetic ammonia wastewater 3 -N concentration is 1275mg / L, COD is 536mg / L. Adjust the pH of the wastewater to 9.5, and then add the purchased industrial grade Na to the wastewater 2 HPO 4 13g / L and MgCl 29g / L, stirred for 20min, precipitated for 10min, harvested solid precipitated struvite, washed 2-3 times with deionized water, and air-dried for later use. The residual concentration of ammonia nitrogen after treatment by this method is 84.2 mg / L, the removal rate of ammonia nitrogen is 93.4%, and the residual concentration of phosphorus is 5 mg / L.

[0033] B. The struvite solid harvested in step A is pyrolyzed with alkali, the alkali is commercially available industrial grade sodium hydroxide, and the amount of alkali added is 0.16 times the quality of the struvite, and pyrolyzed for 2 hours at 90°C, The obtained solid pyrolysis products are phosphate and magnesium salt; the ammonia gas released during the pyrol...

Embodiment 3

[0040] A. Collection of struvite.

[0041] Determination of NH in synthetic ammonia wastewater 3 -N concentration is 1604mg / L, COD is 568mg / L. Adjust the pH of the wastewater to 9.5, and then add industrial-grade commercial NaH to the wastewater 2 PO 4 9g / L and MgSO 4 10g / L, stirred for 20min, precipitated for 15min, harvested solid precipitated struvite, washed 2-3 times with deionized water, and air-dried for later use. The residual concentration of ammonia nitrogen after treatment by this method is 68.1 mg / L, the removal rate of ammonia nitrogen is 94.0%, and the residual concentration of phosphorus is lower than 10 mg / L.

[0042] B, the struvite solid harvested in step A is pyrolyzed with alkali.

[0043] The solid struvite harvested in step A is pyrolyzed with alkali, the alkali is commercially available industrial grade sodium hydroxide, the amount of alkali added is 0.16 times the mass of struvite, and pyrolyzed at 90°C for 2 hours to obtain The solid pyrolysis ...

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Abstract

The invention relates to a struvite circulating crystallization method for treating synthetic ammonia wastewater. The method comprises the following steps of: A, adding soluble phosphate and magnesium salt into the synthetic ammonia wastewater at the ammonium nitrogen concentration of 1,000-2,065mg / L; B, adding alkali into the acquired struvite solid, and performing pyrolysis at the temperature of between 80 and 100DEG C for 1 to 3 hours; C, treating the synthetic ammonia wastewater by using a pyrolysis solid product, and adding a small amount of magnesium salt, wherein ammonia generated in the pyrolysis process is absorbed by a dilute acid solution, and the obtained ammonium salt is used as a raw material for producing a fertilizer; and D, using struvite which cannot be recycled as a sustained-release fertilizer. For the synthetic ammonia wastewater at the ammonium nitrogen concentration of 1,000-2,065mg / L, the struvite can be recycled for 3 to 6 times, the ammonia nitrogen removal rate is higher than 87 percent, the ammonium nitrogen concentration of effluent is lower than 200mg / L, agents are saved through recycle, and nitrogen resources are recycled. The pretreated wastewater meets the requirement of an A / O biochemical treatment process on nitrogen and phosphorus, and can be subjected to biochemical treatment further.

Description

technical field [0001] The invention relates to a method for treating synthetic ammonia wastewater by using struvite cyclic crystallization method, specifically using the struvite cyclic crystallization method to pretreat synthetic ammonia industrial wastewater and reclaim nitrogen resources therein, and then use A / O process for further biochemical treatment Discharge after reaching the standard. The invention belongs to the technical field of resource treatment of synthetic ammonia industrial wastewater. Background technique [0002] Synthetic ammonia industrial wastewater has the characteristics of low carbon and high ammonia nitrogen. The concentration of ammonia nitrogen contained is often greater than 1000mg / L, and the discharge volume is large. If it is directly discharged into the environment or sewage treatment plant without pretreatment, it will cause a large impact load of ammonia nitrogen. Therefore Synthetic ammonia wastewater needs to be treated in the factory ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F9/14C01C1/16C01C1/242C05F17/00C05C3/00
CPCY02P60/21Y02W30/40
Inventor 李咏梅曾庆玲张丹丹刘鸣燕
Owner TONGJI UNIV
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