1. A flue gas desulfurization wastewater treatment method is characterized in that: and (3) carrying out aeration oxidation on the desulfurization wastewater to remove sulfite ions, then adding a heavy metal ion remover to remove heavy metal ions, and discharging the effluent which reaches the standard.

2. The flue gas desulfurization wastewater treatment method according to claim 1, characterized in that: and in the desulfurization wastewater aeration oxidation stage, concentrated sulfuric acid is added into the desulfurization wastewater.

3. The flue gas desulfurization wastewater treatment method according to claim 1, characterized in that: the method for removing the heavy metal ions by adding the heavy metal ion remover comprises the following steps: adding ferrous sulfate and calcium hydroxide into the wastewater, aerating and oxidizing, then adding the calcium hydroxide to adjust the pH value to 9-10, finally settling and separating the wastewater in a thickener, discharging the overflow supernatant after reaching the standard, and performing pressure filtration on the underflow by a filter press to produce heavy metal slag.

4. The utility model provides a flue gas desulfurization effluent disposal system which characterized in that: including oxidation tank (10), the drain pipe of oxidation tank (10) bottom is connected to a reaction tank (20), and the overflow mouth of a reaction tank (20) is connected to aeration oxidation groove (30), the overflow mouth of aeration oxidation groove (30) is connected to secondary reaction tank (40), and the overflow mouth of secondary reaction tank (40) is connected to thickener (50), sets up venturi (60) on desulfurization waste water gets into the pipeline of oxidation tank (10), the contraction section or the choke section of venturi (60) set up air and concentrated sulfuric acid entry.

5. The flue gas desulfurization wastewater treatment system according to claim 4, characterized in that: the middle section of venturi (60) sets up feeder hopper (70), feeder hopper (70) intercommunication air, desulfurization waste water come the material pipe and concentrated sulfuric acid come the material pipe.

6. The flue gas desulfurization wastewater treatment system according to claim 4, characterized in that: be equipped with circulating pump (80) on oxidation tank (10) bottom drain pipe, venturi (60) and a reaction tank (20) all with the drain pipe of circulating pump (80) is connected.

7. The flue gas desulfurization wastewater treatment system according to claim 4, characterized in that: and a gas overflow outlet is arranged at the upper part of the oxidation tank (10).

Background

With the continuous development of flue gas desulfurization technology, more and more technologies can be used for flue gas desulfurization treatment, especially wet desulfurization process is the main technology. The desulfurizing agent is a wide variety of types, and includes oxides or hydroxides of basic metals such as magnesium oxide, magnesium hydroxide, calcium oxide, zinc oxide, and sodium hydroxide. SO in flue gas₂Reacts with a desulfurizing agent to generate a large amount of SO₃ ^2-And a small amount of smoke dust enters the desulfurization system along with the flue gas, so that the desulfurization circulating liquid contains a small amount of heavy metal. In order to maintain the ion concentration balance of the desulfurization circulating liquid, the open-circuit part of the desulfurization liquid is continuously fed to a wastewater treatment process, namely desulfurization wastewater. The desulfurization waste water has high COD, sulfide and heavy metal content indexes and can reach the standard by further treatment. In particular SO in waste water₃ ^2-The COD of the wastewater is seriously exceeded due to overhigh ion concentration, the COD index of the wastewater is reduced by adopting a forced aeration oxidation mode, the oxidation efficiency is insufficient, the COD index of the wastewater is difficult to be reduced below the discharge standard, and the method is a great problem in desulfurization wastewater treatment.

The flue gas desulfurization wastewater zero discharge system disclosed in chinese patent CN111517398A and the method and device for realizing zero discharge of desulfurization wastewater by using full flue gas disclosed in chinese patent CN108006683A are all to concentrate, reduce and even dry flue gas desulfurization wastewater, then treat concentrated solution or dust, realize zero discharge of wastewater in a flue gas desulfurization stage, and atomize and concentrate wastewater by adopting a venturi structure. Although the scheme is called as 'zero discharge of wastewater', the method only evaporates a large amount of water in the wastewater to realize water resource recovery, and is immature in treatment process of COD and heavy metal components in the wastewater.

Disclosure of Invention

The invention aims to provide a treatment process of flue gas desulfurization wastewater, which can be used for efficiently converting and removing sulfite ions in the wastewater and removing and recycling heavy metal ions.

In order to realize the above pair, the technical scheme adopted by the invention is as follows: the desulfurization wastewater is aerated and oxidized to remove sulfite ions, and then a heavy metal ion remover is added to remove heavy metal ions, so that effluent reaches the standard and is discharged.

Specifically, in the desulfurization wastewater aeration oxidation stage, concentrated sulfuric acid is added into the desulfurization wastewater.

The method for removing the heavy metal ions by adding the heavy metal ion remover comprises the following steps: adding ferrous sulfate and calcium hydroxide into the wastewater, aerating and oxidizing, then adding the calcium hydroxide to adjust the pH value to 9-10, finally settling and separating the wastewater in a thickener, discharging the overflow supernatant after reaching the standard, and performing pressure filtration on the underflow by a filter press to produce heavy metal slag.

According to the scheme, the desulfurization wastewater with higher pH is adjusted to be acidic by using the concentrated sulfuric acid, the separation and oxidation effects of sulfite ions in the wastewater are improved, the concentrated sulfuric acid and the sulfite ions can also react to generate sulfur dioxide, and the separation efficiency of the sulfite ions is further improved.

Another object of the present invention is to provide a flue gas desulfurization wastewater treatment system, which can effectively treat desulfurization wastewater in combination with the above treatment method.

In order to achieve the purpose, the invention adopts the technical scheme that: the utility model provides a flue gas desulfurization effluent disposal system, includes the oxidation jar, the drain pipe of oxidation tank bottom is connected to a reaction tank, and the overflow mouth that the overflow mouth of a reaction tank is connected to aeration oxidation groove, aeration oxidation groove is connected to the overflow mouth of secondary reaction tank and is connected to the thickener, sets up venturi on desulfurization waste water gets into the pipeline of oxidation jar, venturi's contraction section or choke section set up air and concentrated sulfuric acid entry.

Above-mentioned scheme utilizes venturi structure to force the suction simultaneously with desulfurization waste water, air, has strengthened the mixed effect of desulfurization waste water, air and concentrated sulfuric acid, has improved oxidation, the conversion efficiency of sulfite ion.

Drawings

FIG. 1 is a schematic view of a flue gas desulfurization wastewater treatment system of the present invention.

Detailed Description

The technical scheme of the invention is further detailed in the following with reference to the accompanying drawings.

The utility model provides a flue gas desulfurization effluent disposal system, includes oxidation tank 10, the drain pipe of oxidation tank 10 bottom is connected to a reaction tank 20, and the overflow mouth of a reaction tank 20 is connected to aeration oxidation groove 30, the overflow mouth of aeration oxidation groove 30 is connected to secondary reaction tank 40, and the overflow mouth of secondary reaction tank 40 is connected to thickener 50, sets up venturi 60 on desulfurization waste water gets into the pipeline of oxidation tank 10, venturi 60's contraction section or choke section set up air and concentrated sulfuric acid entry.

And a circulating pump 80 is arranged on a liquid outlet pipe at the bottom of the oxidation tank 10, and the Venturi tube 60 and the primary reaction tank 20 are connected with the liquid outlet pipe of the circulating pump 80.

Compared with the prior art, this scheme has designed special venturi aerator, and desulfurization waste water is through pumping circulation in the oxidation jar 10, and the liquid that flows at a high speed inhales air and desulfurization waste water in the lump through venturi 60 and forms tiny bubble and liquid intensive mixing, gets into oxidation jar 10 through oxidation jar inlet tangential, and the desulfurization waste water of air bubble is the rotary motion in the oxidation jar on the both sides, and the bubble dwell time is long in the circulating liquid, SO in the circulating liquid₃ ^2-With O in air₂The contact reaction condition is good, and the reaction is full₃ ^2-+O₂→SO₄ ^2-。

The middle section of the venturi tube 60 is provided with a feed hopper 70, and the feed hopper 70 is communicated with an air, a desulfurization wastewater feeding pipe and a concentrated sulfuric acid feeding pipe.

The pH value of the desulfurization wastewater is higher than 7-9, SO that SO in the wastewater is strengthened₃ ^2-And (3) removing and oxidizing, namely adding concentrated sulfuric acid through an automatic valve to adjust the pH value of the circulating liquid in the oxidation tower to 4-6. The automatic valve for adding concentrated sulfuric acid is interlocked with the pH meter for automatic regulation so as to be stableAnd controlling the pH of the circulating liquid. Concentrated sulfuric acid and SO in desulfurization wastewater₃ ^2-Reactions also occur: SO (SO)₃ ^2-+2H⁺→H₂O+SO₂×) 10, the upper part of the oxidation tank is provided with a gas overflow outlet and the generated SO₂The air escaping with the circulating liquid in the oxidation tank is sucked to the flue gas acid making system.

The desulfurized wastewater is treated by adding FeSO into the primary reaction tank 20₄、Ca(OH)₂Adjusting the pH value to 6-7, and stirring for reaction. And then continuously overflows to the aeration oxidation tank 30, and air is continuously blown in by the Roots blower to carry out aeration oxidation, thereby effectively preventing the deposition of particles in the tank. The wastewater in the aeration oxidation tank 30 overflows to the secondary reaction tank 40 through the flowing tank, and Ca (OH) is added₂And adjusting the pH value to 9-10, and removing heavy metals such As Cu, As, Pb, Zn, Mg and the like in the wastewater. And then the supernatant fluid is settled and separated by a thickener 50, the overflow supernatant fluid is discharged or recycled after reaching the standard, and the bottom of the thickener is pressed and filtered by a filter press to produce neutralized slag.

According to the technical scheme, concentrated sulfuric acid is added during aeration oxidation, SO that the conversion efficiency of sulfite ions is greatly improved, and the generated SO₂The gas is collected and enters a flue gas acid making system to reach SO in the flue gas₂The dual purposes of recovery, efficacy creating, cleaning, environmental protection and environmental pollution prevention are achieved, and the treatment process has the characteristics of high efficiency, cleanness and stability aiming at the control of indexes of COD, sulfide and heavy metal in the desulfurization wastewater treatment.