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Method for removing nitrogen and phosphorus in wastewater by utilizing magnesium salt in desulfurization wastewater

A technology for desulfurization wastewater and magnesium salts, applied in water/sewage treatment, chemical instruments and methods, water/sludge/sewage treatment, etc., can solve the problem of high operating costs and achieve the effect of improving purity

Inactive Publication Date: 2019-03-22
SHANGHAI UNIVERSITY OF ELECTRIC POWER
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, when treating high-concentration phosphorus and ammonia nitrogen wastewater, the addition of a large amount of magnesium salts makes the operation cost of this method very high

Method used

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  • Method for removing nitrogen and phosphorus in wastewater by utilizing magnesium salt in desulfurization wastewater

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] Removal of magnesium salts from desulfurization wastewater and recovery of condensate polishing to treat ammonia nitrogen in regenerated wastewater. The experiment was carried out on a six-connected mixer, including two parts: magnesium salt recovery and regenerated wastewater treatment. The specific steps are as follows:

[0043] The first part, magnesium salt recovery process

[0044] The first step is to use Ca(OH) 2 Adjust the pH value of the desulfurization wastewater to 9.0-10.0, stir with a stirrer at a speed of 300 rpm for 3 minutes, settle for 0.2-1 hour, and take the supernatant;

[0045] The second step, the organic sulfur of 20~80mg / L waste water and the Na of 10~40mg / L are added in the supernatant described in the first step. 2 S, after stirring with a stirrer at a speed of 300 rpm for 3 minutes, carry out precipitation treatment for 0.2 to 1 hour, and take the supernatant;

[0046] In the third step, add polyaluminium chloride 40~80mg / L in the supernatant ...

Embodiment 2

[0053] Desulfurization wastewater magnesium salt removal and recovery of nitrogen and phosphorus in concentrated dewatered sludge water, the experiment was carried out on a six-connected mixer, including magnesium salt recovery and concentrated dewatered sludge water treatment two parts, the specific steps are as follows:

[0054] The first part is described with the first part in the example 1;

[0055] The second part, concentrated dewatered sludge water treatment

[0056] The first step is to analyze the water quality of the concentrated dewatered sludge water. The content of ammonia nitrogen is 341.62 mg / L, and the content of phosphorus is 64.46 mg / L; the recovered magnesium salt is added to the concentrated dewatered sludge water so that the Mg:P molar ratio is 2 :1, adjust the pH value to 8.0-9.0;

[0057] In the second step, stir at a speed of 150 revolutions per minute for 30 minutes; after standing for 0.2 to 1 hour to separate layers, take the supernatant to measure...

Embodiment 3

[0060] Removal of magnesium salts from desulfurization wastewater and recovery of condensate polishing to treat ammonia nitrogen in regenerated wastewater. The experiment was carried out on a six-connected mixer, including two parts: magnesium salt recovery and regenerated wastewater treatment. The specific steps are as follows:

[0061] The first part, magnesium salt recovery process

[0062] The first step is to use Ca(OH) 2 Adjust the pH value of the desulfurization wastewater to about 11, stir with a stirrer at a speed of 300 rpm for 3 minutes, settle for about 0.1 hour, and take the supernatant;

[0063] In the second step, add 100mg / L of Na in the supernatant described in the first step 2 S, after stirring with a stirrer at a speed of 300 rpm for 3 minutes, carry out precipitation treatment for about 0.1 hour, and take the supernatant;

[0064] The 3rd step, add ferric chloride, polyferric sulfate, ferrous sulfate (mass ratio is 1:1:1) in the supernatant described in t...

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Abstract

The invention relates to a method for removing nitrogen and phosphorus in wastewater by utilizing a magnesium salt in desulfurization wastewater. The method comprises the following steps: (1) introducing desulfurization wastewater into a pre-precipitation unit, adding lime, and performing pre-precipitation treatment; (2) adding sulfide into a heavy metal advanced removal unit for advanced removalof heavy metals; (3) adding a coagulant and a coagulant aid into a coagulation precipitation unit for coagulation precipitation; (4) adding Mg(OH)2 seed crystal, NaOH and a coagulant aid are added into a magnesium removal recovery unit to remove Mg<2+> and recover a magnesium salt precipitate; and (5) adding the magnesium salt precipitate recovered in the step (4) into a struvite crystallization unit in which phosphorus / ammonia nitrogen wastewater is introduced, and carrying out reaction and precipitation to remove nitrogen and phosphorus from the wastewater. Compared with the prior art, the method provided by the invention solves the difficult problem of treating desulfurization wastewater and softening sludge, realizes removal of phosphorus and nitrogen from wastewater while recovering nitrogen and phosphorus, and has practical significance of 'treating waste with waste' and recycling.

Description

technical field [0001] The invention belongs to the technical field of comprehensive utilization of waste water resources, and relates to a method for removing nitrogen and phosphorus in waste water by using magnesium salt in desulfurization waste water. Background technique [0002] The water quality of desulfurization wastewater is related to many factors such as desulfurization process, flue gas ash content and desulfurization agent. Among the many desulfurization methods, flue gas wet desulfurization and seawater desulfurization are the most commonly used methods at present. Due to sulfur dioxide (SO 2 ), the wet desulfurization waste liquid is acidic (pH 4-6), and the suspended matter is 9000-12700mg / L, which mainly includes gypsum particles, silicon dioxide, iron and aluminum hydroxides, and mercury , lead, nickel, zinc and other heavy metals and non-metals such as arsenic and fluorine. Since heavy metals are mostly toxic, they must be removed by treatment. [0003]...

Claims

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Application Information

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IPC IPC(8): C02F1/52C01B25/45C02F101/10C02F101/16C02F103/18
CPCC01B25/451C02F1/5236C02F2101/10C02F2101/105C02F2101/16C02F2103/18
Inventor 周振王凯冲赵晓丹涂成钦杨家哲江婕明强
Owner SHANGHAI UNIVERSITY OF ELECTRIC POWER
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