CN111217484A - Desulfurization wastewater recycling treatment method - Google Patents
Desulfurization wastewater recycling treatment method Download PDFInfo
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Abstract
The invention relates to the field of industrial wastewater treatment, in particular to a desulfurization wastewater recycling treatment method, which comprises the following steps: sequentially adding sodium hydroxide and sodium sulfate into the desulfurization wastewater to remove magnesium ions and calcium ions; adding a flocculating agent and a coagulant aid into the desulfurization wastewater treated by the steps to remove colloidal substances and heavy metals; evaporating and crystallizing the treated desulfurization wastewater to obtain secondary steam condensate, inorganic salt and mother liquor; and (3) repeatedly carrying out treatment of removing calcium and magnesium ions, colloidal substances, heavy metals and evaporative crystallization on the mother liquor until zero discharge of the mother liquor is realized. The purity of the inorganic salt prepared by the method can reach more than 90 percent, and the mother liquor is subjected to organic matter removal, and the wastewater treatment step is repeated again, so that near zero emission of the mother liquor is finally realized, and the waste of resources and secondary pollution to the environment are reduced. Therefore, compared with other conventional treatment processes, the method has the advantages that the membrane, electrolysis and electrodialysis processes are not used, the treatment cost of the ton desulfurization wastewater is low, and the investment and operation cost are greatly reduced.
Description
Technical Field
The invention relates to the field of industrial wastewater treatment, in particular to a desulfurization wastewater recycling treatment method.
Background
With the increase of the installed capacity of thermal power plants in China, the discharge amount of sulfur dioxide in thermal power plants is synchronously increased, and in order to avoid atmospheric pollution, flue gas needs to be desulfurized, while the method adopted in flue gas desulfurization projects of domestic and foreign coal-fired power plants is mainly limestone-gypsum method, but the system can generate a large amount of desulfurization waste water. The desulfurization wastewater contains a large amount of suspended matters, sulfates and chlorides, has high hardness and salt content, contains a certain amount of heavy metal ions, has great harm to the environment and needs to be strictly treated. With the continuous improvement of environmental requirements, the deep treatment and reuse of the desulfurization wastewater, and the realization of zero discharge of the wastewater is a trend of desulfurization wastewater treatment.
The traditional triple-header process removes suspended matters, heavy metals and other substances in the desulfurization wastewater after neutralization, flocculation and precipitation treatment, cannot ensure the treatment effect, has higher salt content in the treated water, and cannot reuse other systems. The evaporation technology is an effective technology for realizing zero emission of the desulfurization wastewater, but the direct evaporation water quantity is large, the steam consumption or the power consumption is extremely high, and the investment and the operation cost are high. The membrane separation method, such as nanofiltration and reverse osmosis, has the problems of low concentration, low efficiency and incapability of recycling water resources. The electrodialysis is adopted only, so that the investment is large, the operating cost is high, and the problem that the reuse water cannot meet the latest national discharge standard exists. Forward osmosis belongs to a new technology in the application of desulfurization wastewater, but the technology is complex, the selectivity of a membrane and a draw solution is low, the technical maturity is low, and the energy consumption is high.
Therefore, the development of a novel desulfurization wastewater treatment process realizes the recycling of the desulfurization wastewater according to the quality, increases the recycling rate of the wastewater and reduces the operation cost, and is the key of the advanced treatment recycling and zero discharge of the desulfurization wastewater.
Drawings
FIG. 1 is a process flow diagram of the wastewater treatment method of the present invention.
In the drawings, the components represented by the respective reference numerals are listed below:
1. the device comprises a regulating tank, 2, a first-stage reaction tank, 3, a second-stage reaction tank, 4, sedimentation tanks A and 5, a flocculation reaction tank, 6, sedimentation tanks B and 7, a pH regulating tank, 8, an evaporative crystallizer, 9, a centrifugal machine, 10 and a COD adsorption device.
Disclosure of Invention
The invention aims to solve the technical problem of providing a desulfurization wastewater recycling treatment method, and solves the problems of low wastewater reuse rate, high operation cost and incapability of realizing zero discharge in the conventional desulfurization wastewater treatment method.
The technical scheme for solving the technical problems is as follows: a desulfurization wastewater recycling treatment method comprises the following steps:
sequentially adding sodium hydroxide and sodium sulfate into the desulfurization wastewater to remove magnesium ions and calcium ions; adding a flocculating agent and a coagulant aid into the desulfurization wastewater treated by the steps to remove colloidal substances and heavy metals; evaporating and crystallizing the treated desulfurization wastewater to obtain secondary steam condensate, inorganic salt and mother liquor; and (3) repeatedly carrying out treatment of removing calcium and magnesium ions, colloidal substances, heavy metals and evaporative crystallization on the mother liquor until zero discharge of the mother liquor is realized.
The desulfurization wastewater treatment method comprises the following steps: firstly, sequentially adding sodium hydroxide and sodium sulfate into desulfurization wastewater, and precipitating magnesium ions and calcium ions in the wastewater in the forms of calcium sulfate and magnesium hydroxide respectively so as to remove the magnesium ions and the calcium ions in the wastewater; then, adding a flocculating agent and a coagulant aid into the treated desulfurization wastewater to enable colloidal substances and heavy metals in the wastewater to settle along with the flocculating agent and the coagulant aid, and further removing the colloidal substances and the heavy metals in the wastewater; then conveying the desulfurization wastewater treated in the step into an evaporation crystallizer, and carrying out evaporation crystallization treatment on the wastewater by the evaporation crystallizer to obtain inorganic salt and water vapor with high purity, wherein the water vapor can be directly discharged after being condensed; and finally, repeatedly removing calcium and magnesium ions, colloidal substances, heavy metals and evaporating and crystallizing the mother liquor until the mother liquor is nearly zero-emission. The purity of the inorganic salt prepared by the method can reach more than 90 percent, and the mother liquor can also repeat the step of wastewater treatment, so that near zero emission of the mother liquor is finally realized, and the waste of resources and secondary pollution to the environment are reduced. Therefore, compared with other conventional treatment processes, the method has the advantages that the membrane, electrolysis and electrodialysis processes are not used, the treatment cost of the ton desulfurization wastewater is low, and the investment and operation cost are greatly reduced.
Further, the method specifically comprises the following steps:
s1, adding sodium hydroxide into the desulfurization wastewater to remove magnesium ions;
s2, adding sodium sulfate into the desulfurization wastewater treated by the S1, reacting and precipitating to further remove magnesium ions and calcium ions;
s3, adding a flocculating agent and a coagulant aid into the desulfurization wastewater treated by the S2, reacting and precipitating to remove colloidal substances and heavy metals;
s4, adjusting the desulfurization wastewater treated by the S3 to be alkalescent;
s5, carrying out evaporative crystallization on the desulfurization wastewater treated by the S4, and adding calcium sulfate crystal seeds to obtain secondary steam condensate, inorganic salt and mother liquor;
and S6, repeatedly performing treatment of removing calcium and magnesium ions, colloidal substances, heavy metals and evaporative crystallization after the mother liquor is subjected to ozone oxidation or activated carbon adsorption treatment until zero discharge of the mother liquor is realized.
The invention specifically comprises the following steps: in step S1, before adding sodium hydroxide to the desulfurization wastewater, the wastewater may be placed in a conditioning tank to perform homogenization treatment on the wastewater, thereby ensuring the stability of the wastewater treatment system and method. After the wastewater is homogenized, sodium hydroxide is added into the wastewater, so that magnesium ions in the wastewater are settled in the form of magnesium hydroxide to remove the magnesium ions. In the step S2, sodium sulfate is added into the wastewater treated in the step S1, part of calcium ions are settled in the form of calcium sulfate to remove part of the calcium ions, and at the moment, part of the residual magnesium ions in the system can also be settled in the form of magnesium hydroxide, and after the settling reaction is finished, the system is fully settled, so that the aim of removing the calcium ions and the magnesium ions in the wastewater is fulfilled. In step S3, a flocculating agent and a coagulant aid are further added to the wastewater, and the wastewater is sufficiently stirred to flocculate colloidal substances and heavy metals in the wastewater, and then the system is sufficiently precipitated, thereby achieving the purpose of removing the colloidal substances and heavy metals in the wastewater. In step S4, the treated wastewater is adjusted to be weakly alkaline so as to reduce the corrosion of the wall of the evaporative crystallizer caused by the wastewater entering the evaporative crystallizer. In step S5, the desulfurization wastewater treated in step S4 is transferred to an evaporative crystallizer, and calcium sulfate seed crystals are added to the system, so that the wastewater is heated and boiled in the evaporative crystallizer to make the solution reach a supersaturated state, and further part of solute in the wastewater is deposited on the surface of the calcium sulfate seed crystals to grow crystals, thereby obtaining inorganic salt with high purity. In step S6, after the mother liquor obtained in step S5 is subjected to ozone oxidation or activated carbon adsorption, the processes of removing calcium and magnesium ions, colloidal substances, heavy metals and evaporative crystallization are repeated until the mother liquor is nearly zero-emission, so that the near zero-emission of the mother liquor can be realized, and the waste of resources and the secondary pollution to the environment are reduced.
Further, in step S1, sodium hydroxide is added into the desulfurization wastewater, the pH value of the system is controlled to be 11-12, and the reaction time is 1-2 h.
Research shows that when sodium hydroxide is added into the desulfurization wastewater, the pH value of the system is controlled to be 11-12, and the reaction time is 1-2h, so that magnesium ions in the wastewater can be effectively removed, and the energy consumption can be saved.
Further, in step S2, after adding sodium sulfate, reacting for 2-3 hours under stirring, and controlling the concentration ratio of calcium ions to sulfate ions in the system to be 1: (2.6-3.2); the precipitation time is 7-8 h.
Research shows that after sodium sulfate is added into wastewater, the wastewater reacts for 2-3 hours under the stirring condition to fully react, and after the reaction is finished, the wastewater is deposited in a deposition tank for 7-8 hours to fully deposit magnesium ions and calcium ions so as to effectively remove calcium and magnesium ions, and in addition, the amount of the added sodium sulfate also needs to ensure that the concentration ratio of the calcium ions to sulfate ions in the system is 1: (2.6-3.5) and preparing the wastewater to enter an evaporative crystallizer.
Further, in step S3, the flocculant and coagulant aid are PAC and PAM, respectively; the precipitation time is 5-6 h.
Colloidal substances and heavy metals in the desulfurization wastewater can be subjected to flocculation and precipitation by adding PAM and PAC flocculants, the flocculants and the coagulant aids are added, then the mixture is stirred at a constant speed to fully react, so that the substances such as the colloidal substances, the heavy metals and the like in the wastewater are further removed, and finally the supernatant is conveyed to a clarification tank.
Further, in step S4, the pH of the desulfurization waste water is adjusted to 7.5 to 8.5.
The pH value of the desulfurization wastewater is adjusted to 7.5-8.5, so that the corrosion and damage of the wastewater with stronger acidity or alkalinity to an evaporation crystallizer can be effectively prevented.
Further, in step S5,
the dosage of the calcium sulfate seed crystal is 3-6 g/L;
during the evaporation crystallization, the pressure is 80-120KPa, and the temperature is 90-130 ℃;
during evaporation and crystallization, the concentration ratio of calcium ions to sulfate ions in the system is 1: (2-3), the concentration of the calcium sulfate seed crystal is 15-35g/L, the concentration of magnesium ions is less than 7g/L, and the COD value is less than 8000 mg/L.
After the wastewater is conveyed into the evaporative crystallizer, the dosage of calcium sulfate crystal seeds, the concentration of magnesium ions and the concentration of calcium ions and sulfate ions in a system need to be controlled, so that the normal operation of the evaporative crystallizer can be ensured, the scaling of the inner wall surface of the evaporative crystallizer can be prevented, the COD value is controlled below 8000mg/L, and organic matters in the wastewater can be prevented from being attached to the surface of an inorganic salt crystal so as to influence the purity of inorganic salt.
Further, step S5 includes centrifuging the inorganic salt, and repeating the evaporation and crystallization of the centrifuged inorganic salt mother liquor until the purity of the inorganic salt is greater than 90%.
And after the inorganic salt obtained in the step S5 is subjected to centrifugal treatment, the inorganic salt is refluxed to an evaporative crystallization system to continue evaporation, concentration and crystallization, so that the purity of the inorganic salt can be further improved.
Further, in step S6, after the mother liquor is treated by ozone oxidation or activated carbon adsorption at a speed of 500-1000L/h to remove COD, the steps are repeated to realize zero emission of the mother liquor.
The mother liquor generated by the evaporative crystallizer is subjected to ozone oxidation or activated carbon adsorption treatment at the speed of 500-1000L/h to remove COD, and then the treatment of removing calcium and magnesium ions, colloidal substances, heavy metals and evaporative crystallization is repeated, so that near zero emission of the mother liquor can be finally realized, and the maximization of water resource utilization is realized.
Compared with the prior art, the desulfurization wastewater treatment method has the beneficial effects that:
1. compared with other conventional treatment processes, the treatment method has the advantages that the membrane-free, electrolysis and electrodialysis processes are not used, the ton desulfurization wastewater treatment cost is low, and the investment and operation cost is greatly reduced;
2. in the desulfurization wastewater recycling treatment method provided by the invention, the mother liquor subjected to evaporative crystallization is subjected to ozone oxidation or activated carbon adsorption, and then the treatment steps are repeated, so that near zero emission of the mother liquor can be realized, and the waste of resources and secondary pollution to the environment are reduced;
3. in the desulfurization wastewater recycling treatment method provided by the invention, the scaling of the inner wall surface of the evaporation crystallizer during operation can be prevented by a seed crystal process, so that the long-term stable operation of the evaporation crystallizer is maintained;
4. the wastewater treatment method has high salt recovery rate, two inorganic salts, namely sodium chloride and calcium sulfate (gypsum), are prepared by evaporative crystallization, the purity can reach more than 90 percent, and compared with the traditional electrolysis process, the desulfurization wastewater can be recycled to the maximum extent;
5. according to the wastewater treatment method, the evaporative crystallization steam condensate water is subjected to simple treatment, meets the corresponding local standard, and can be recycled or discharged after reaching the standard.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms also include the plural forms unless the context clearly dictates otherwise, and further, it is understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of the stated features, steps, operations, devices, components, and/or combinations thereof.
Hereinafter, embodiments of the present invention will be described in detail. The following examples are only for illustrating the technical solutions of the present invention more clearly, and therefore are only examples, and the protection scope of the present invention is not limited thereby.
The following examples of desulfurization wastewater influent water quality were: COD is 140mg/L, calcium ion content is 1800mg/L, magnesium ion content is 2800mg/L, sulfate ion content is 3000mg/L, chloride ion content is 12000mg/L, and water inlet amount is 50m3H is used as the reference value. The process flow of the wastewater treatment method is shown in figure 1.
Example 1
Step S11: conveying the desulfurization wastewater from the regulating tank 1 to the primary reaction tank 2 through a pump, adding 10g/L of sodium hydroxide into the primary reaction tank 2, stirring at a constant speed to ensure that the pH value of the wastewater is 11.2, and reacting for 1.4h to remove magnesium ions in the desulfurization wastewater;
step S12: conveying the supernatant which is uniformly stirred and completely reacted in the step S11 to a secondary reaction tank 3, adding 11.54g/L of sodium sulfate into the secondary reaction tank 3, reacting for 2 hours under the stirring condition, and controlling the concentration ratio of calcium ions to sulfate ions to be 1: 2.6; then, the supernatant is conveyed to a sedimentation tank A4 through an axial flow pump, and sedimentation treatment is carried out for 7 hours so as to further remove magnesium ions and a certain amount of calcium ions in the desulfurization wastewater;
step S13: overflowing the supernatant into a flocculation reaction tank 5, adding PAM and PAC, and fully reacting under stirring; then, conveying the supernatant to a sedimentation tank B6, and carrying out sedimentation treatment for 5 hours to further remove colloidal substances, heavy metals and the like in the desulfurization wastewater;
step S14: conveying the supernatant in the step S13 to a pH adjusting tank 7, and adjusting the pH value of the desulfurization wastewater to 7.5;
step S15: conveying the desulfurization wastewater with the pH value of 7.5 in the step S14 to an evaporative crystallizer 8, wherein the absolute pressure of the operating conditions of the evaporative crystallizer 8 is 80KPa, the temperature is 95 ℃, the calcium sulfate crystal seed is 15g/L, the COD concentration is 8000mg/L, and the magnesium ion concentration is 6 g/L;
step S16: the mother liquor generated by the evaporation crystallizer 8 in the step S15 passes through the COD adsorption device 10 at a rate of 500L/h, namely after COD is removed by ozone oxidation or activated carbon adsorption, the mother liquor returns to the primary reaction tank 2; after centrifugal treatment by a centrifuge 9, inorganic salt flows back to the evaporative crystallizer 8 to continue evaporation, concentration and crystallization.
The product obtained by the method is inorganic salt A which is gypsum and has the purity of 95 percent, inorganic salt B which is sodium chloride and has the purity of 97 percent, the whole system is continuously and stably operated for more than half a year, no secondary pollution is caused, no mother liquor is discharged, the resource utilization is maximized, and the crystallizer is free of scaling.
Example 2
Step S21: conveying the desulfurization wastewater from the regulating tank 1 to the primary reaction tank 2 through a pump, adding 11g/L of sodium hydroxide into the primary reaction tank 2, stirring at a constant speed to ensure that the pH value of the wastewater is 11.6, and reacting for 1.4h to remove magnesium ions in the desulfurization wastewater;
step S22: conveying the supernatant which is uniformly stirred and completely reacted in the step S21 to a secondary reaction tank 3, adding 21.12g/L of sodium sulfate into the secondary reaction tank 3, reacting for 2.5 hours under the stirring condition, and controlling the concentration ratio of calcium ions to sulfate ions to be 1: 2.8; then, the supernatant is conveyed to a sedimentation tank A4 through an axial flow pump, and sedimentation treatment is carried out for 7.5 hours so as to further remove magnesium ions and a certain amount of calcium ions in the desulfurization wastewater;
step S23: overflowing the supernatant into a flocculation reaction tank 5, adding PAM and PAC, and fully reacting under stirring; then, the supernatant is conveyed to a sedimentation tank B6, and sedimentation treatment is carried out for 5.5 hours so as to further remove colloidal substances, heavy metals and the like in the desulfurization wastewater;
step S24: and (4) conveying the supernatant in the step S23 to a pH adjusting tank 7, and adjusting the pH value of the desulfurization wastewater to 8.
Step S5: conveying the desulfurization wastewater with the pH value of 8 in the step S4 to an evaporative crystallizer 8, wherein the operating conditions of the evaporative crystallizer 8 comprise an absolute pressure of 100KPa, a temperature of 109 ℃, a calcium sulfate crystal seed of 20g/L, a COD concentration of 6000mg/L and a magnesium ion concentration of 5 g/L;
step S26: the mother liquor generated by the evaporation crystallizer 8 in the step S25 passes through the COD adsorption device 10 at 625L/h, i.e., after COD is removed by ozone oxidation or activated carbon adsorption, the mother liquor is refluxed to the primary reaction tank 2; after centrifugal treatment by a centrifuge 9, inorganic salt flows back to the evaporative crystallizer 8 to continue evaporation, concentration and crystallization.
The product obtained by the method is inorganic salt A which is gypsum and has the purity of 95 percent, inorganic salt B which is sodium chloride and has the purity of 97 percent, the whole system is continuously and stably operated for more than half a year, no secondary pollution is caused, no mother liquor is discharged, the resource utilization is maximized, and the crystallizer is free of scaling.
Embodiment 3
Step S31: conveying the desulfurization wastewater from the regulating tank 1 to the primary reaction tank 2 through a pump, adding 12g/L of sodium hydroxide into the primary reaction tank 2, stirring at a constant speed to ensure that the pH value of the wastewater is 12, and reacting for 2 hours to remove magnesium ions in the desulfurization wastewater;
step S32: conveying the supernatant which is uniformly stirred and completely reacted in the step S31 to a secondary reaction tank 3, adding 24.4g/L sodium sulfate into the secondary reaction tank 3, reacting for 3 hours under the stirring condition, and controlling the concentration ratio of calcium ions to sulfate ions to be 1: 3.2; then, the supernatant is conveyed to a sedimentation tank A4 through an axial flow pump, and sedimentation treatment is carried out for 8 hours so as to further remove magnesium ions and a certain amount of calcium ions in the desulfurization wastewater;
step S33: overflowing the supernatant into a flocculation reaction tank 5, adding PAM and PAC, and fully reacting under stirring; then, conveying the supernatant to a sedimentation tank B6, and carrying out sedimentation treatment for 6 hours so as to further remove colloidal substances, heavy metals and the like in the desulfurization wastewater;
step S34: and (4) conveying the supernatant in the step S33 to a pH adjusting tank 7, and adjusting the pH value of the desulfurization wastewater to 8.5.
Step S35: conveying the desulfurization wastewater with the pH value of 8.5 in the step S34 to an evaporative crystallizer 8, wherein the absolute pressure of the operating conditions of the evaporative crystallizer 8 is 120KPa, the temperature is 130 ℃, the calcium sulfate crystal seed is 35g/L, the COD concentration is 5000mg/L, and the magnesium ion concentration is 5 g/L;
step S36: the mother liquor generated by the evaporation crystallizer 8 in the step S35 passes through the COD adsorption device 10 at 1000L/h, namely after COD is removed by ozone oxidation or activated carbon adsorption, the mother liquor returns to the primary reaction tank 2; after centrifugal treatment by a centrifuge 9, inorganic salt flows back to the evaporative crystallizer 8 to continue evaporation, concentration and crystallization.
The product obtained by the method is inorganic salt A which is gypsum and has the purity of 95 percent, inorganic salt B which is sodium chloride and has the purity of 97 percent, the whole system is continuously and stably operated for more than half a year, no secondary pollution is caused, no mother liquor is discharged, the resource utilization is maximized, and the crystallizer is free of scaling.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (9)
1. A desulfurization wastewater recycling treatment method is characterized by comprising the following steps:
sequentially adding sodium hydroxide and sodium sulfate into the desulfurization wastewater to remove magnesium ions and calcium ions; adding a flocculating agent and a coagulant aid into the desulfurization wastewater treated by the steps to remove colloidal substances and heavy metals; evaporating and crystallizing the treated desulfurization wastewater to obtain secondary steam condensate, inorganic salt and mother liquor; and (3) repeatedly carrying out treatment of removing calcium and magnesium ions, colloidal substances, heavy metals and evaporative crystallization on the mother liquor until zero discharge of the mother liquor is realized.
2. The processing method according to claim 1, characterized in that it comprises in particular the steps of:
s1, adding sodium hydroxide into the desulfurization wastewater to remove magnesium ions;
s2, adding sodium sulfate into the desulfurization wastewater treated by the S1, reacting and precipitating to further remove magnesium ions and calcium ions;
s3, adding a flocculating agent and a coagulant aid into the desulfurization wastewater treated by the S2, reacting and precipitating to remove colloidal substances and heavy metals;
s4, adjusting the desulfurization wastewater treated by the S3 to be alkalescent;
s5, carrying out evaporative crystallization on the desulfurization wastewater treated by the S4, and adding calcium sulfate crystal seeds to obtain secondary steam condensate, inorganic salt and mother liquor;
and S6, repeatedly performing treatment of removing calcium and magnesium ions, colloidal substances, heavy metals and evaporative crystallization after the mother liquor is subjected to ozone oxidation or activated carbon adsorption treatment until zero discharge of the mother liquor is realized.
3. The treatment method according to claim 2, wherein in step S1, sodium hydroxide is added into the desulfurization wastewater, the pH value of the system is controlled to be 11-12, and the reaction time is 1-2 h.
4. The treatment method according to claim 3, wherein in step S2, after adding sodium sulfate, the mixture is reacted for 2-3 hours under stirring, and the concentration ratio of calcium ions to sulfate ions in the system is controlled to be 1: (2.6-3.2); the precipitation time is 7-8 h.
5. The treatment method according to claim 3, wherein in step S3, the flocculant and coagulant aid are PAC and PAM, respectively; the precipitation time is 5-6 h.
6. The treatment method according to claim 3, wherein in step S4, the pH of the desulfurized wastewater is adjusted to 7.5 to 8.5.
7. The processing method according to claim 3, wherein, in step S5,
the dosage of the calcium sulfate seed crystal is 3-6 g/L;
during the evaporation crystallization, the pressure is 80-120KPa, and the temperature is 90-130 ℃;
during evaporation and crystallization, the concentration ratio of calcium ions to sulfate ions in the system is 1: (2.6-3.2), the concentration of the calcium sulfate seed crystal is 15-35g/L, the concentration of magnesium ions is less than 7g/L, and the COD value is less than 8000 mg/L.
8. The process of claim 3, wherein step S5 further comprises centrifuging the inorganic salt, and repeating the evaporative crystallization of the centrifuged mother liquor until the purity of the inorganic salt is greater than 90%.
9. The treatment method according to claim 3, wherein in step S6, after the mother liquor is treated by ozone oxidation or activated carbon adsorption at a speed of 500-1000L/h to remove COD, the treatment of removing calcium and magnesium ions, colloidal substances, heavy metals and evaporative crystallization is repeated until zero emission of the mother liquor is achieved.
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Cited By (5)
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| CN112429877A (en) * | 2020-11-16 | 2021-03-02 | 北京清新环境技术股份有限公司 | Method for reducing chloride ion concentration in wastewater |
| CN112875829A (en) * | 2021-01-25 | 2021-06-01 | 江苏海容热能环境工程有限公司 | Desulfurization wastewater purification system and purification method based on self-crystallization fluidized bed |
| CN114368873A (en) * | 2021-12-24 | 2022-04-19 | 江苏卓生源环保科技有限公司 | Desalination and resource treatment method for sintering desulfurization wastewater |
| CN114920409A (en) * | 2022-06-15 | 2022-08-19 | 苏州苏净环保工程有限公司 | Zero-emission treatment system and method for nitrogen and phosphorus-containing wastewater of automobile part factory |
| CN115367902A (en) * | 2021-05-18 | 2022-11-22 | 国家能源投资集团有限责任公司 | High-salinity wastewater pretreatment method and application thereof |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112429877A (en) * | 2020-11-16 | 2021-03-02 | 北京清新环境技术股份有限公司 | Method for reducing chloride ion concentration in wastewater |
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| CN114920409A (en) * | 2022-06-15 | 2022-08-19 | 苏州苏净环保工程有限公司 | Zero-emission treatment system and method for nitrogen and phosphorus-containing wastewater of automobile part factory |
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