Low-cost treatment method for industrial high-salinity wastewater

Abstract

The invention discloses a low-cost treatment method for industrial high-salinity wastewater, relates to the technical field of wastewater treatment.The low-cost treatment method aims at solving the problems that the treatment effect is poor, membrane pollution is serious, the system watering rate is low and the process operation cost is too high, and comprises the following steps that the industrial high-salinity wastewater is injected into a first-stage Fenton oxidation reaction tank; h2O2 is added for an oxidation reaction; the industrial high-salinity wastewater is injected into a secondary Fenton oxidation reaction tank, and H2O2 is continuously added for an oxidation reaction; injecting the industrial high-salinity wastewater into a defluorination reaction tank, adding excessive calcium chloride, then adding a flocculating agent PAM, stirring and precipitating; taking supernate, injecting the supernate into a dechlorination reaction tank, adding calcium-aluminum salt for reaction, and adding a flocculating agent PAM into a reaction device at the same time; taking supernate, injecting the supernate into a flocculation sedimentation tank, adding calcium oxide and a flocculating agent PAM, stirring and mixing, and standing for sedimentation; taking supernate and injecting the supernate into a coke powder adsorption tank, and finally discharging the supernate out of the coke powder adsorption tank to obtain treated effluent.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a low-cost treatment method for industrial high-salt wastewater. Background Art

[0002] Wastewater reuse is the ultimate goal of wastewater treatment. However, after the wastewater is treated by reverse osmosis, while most of the primary pure water is obtained, a large proportion of high-salinity brine is also produced. Brine is an inevitable product of the reverse osmosis desalination process and contains very high organic matter and salt concentrations. The amount of brine is about 25% of the reverse osmosis treated water. This high-concentration brine will accelerate the scaling and corrosion of the process pipeline. If it is discharged directly, it will also cause serious damage to the ecological environment, such as land salinization, which seriously threatens people's production safety.

[0003] In the prior art, for example, the patent titled "A Forward Osmosis Seawater Desalination Concentrated Brine Treatment Process and Treatment System" with publication number CN200910070804.8 discloses an osmotic seawater desalination concentrated brine treatment process, which uses a forward osmosis membrane module, uses seawater desalinated concentrated brine as the extraction liquid, and uses fresh water as the feed liquid. The seawater desalinated concentrated brine is mixed with part of the fresh water that permeates the feed liquid side on the permeation side of the forward osmosis membrane module to become diluted standard brine, and then discharged from the forward osmosis membrane module, and the remaining part of the feed liquid is discharged from the forward osmosis membrane module. This technology can only be used for the treatment of seawater concentrated brine, and is not suitable for the metallurgical industry concentrated brine process.

[0004] For example, the patent name is "A desalination process for concentrated brine" and the publication number is CN201010283192.3, which discloses a desalination process for concentrated brine, which uses pervaporation technology to desalinate concentrated brine and recover pure water. This process maximizes the concentration of concentrated brine, with a high desalination rate and low effluent conductivity. At the same time, combined with heat recovery technology, it greatly reduces the overall energy consumption of the system and can be used for the desalination of reverse osmosis concentrated drainage, circulating cooling sewage and lamp wastewater. This technology has high operating energy consumption and requires the concentrated brine to be heated to above 60 degrees. It can only remove salt from the concentrated brine and cannot effectively remove organic matter in the concentrated water.

[0005] For example, the patent titled "A zero-discharge treatment process for concentrated brine in a steel plant" and the publication number CN1030773143B uses a three-stage reverse osmosis process to concentrate wastewater, followed by evaporation and crystallization. The three-stage reverse osmosis concentration not only has a high operating cost, but the process also does not take into account the organic pollution and inorganic scaling problems of the reverse osmosis membrane, limiting its promotion and application.

[0006] For example, the patent name is "A high-efficiency liquid zero-discharge wastewater treatment method and system", and the publication number is CN103253820B. Although the system has the advantages of low energy consumption and high efficiency, the mixed salt obtained cannot be disposed of and becomes a secondary pollutant or even a hazardous waste. Therefore, the problem of recycling of solid salts is not solved, and this problem still plagues the further development of the company.

[0007] In summary, the existing industrial high-salt wastewater treatment process has the disadvantages of poor treatment effect, serious membrane pollution, low system water addition rate, and high process operation cost. Therefore, developing a low-cost and efficient industrial brine treatment method can not only save a lot of new water resources for enterprises, but also significantly reduce the discharge of brine, which will reduce the adverse effects of wastewater discharge on surrounding waters. Summary of the invention

[0008] The present invention proposes a low-cost method for treating industrial high-salt wastewater, which comprises the following steps: S1: Inject industrial high-salt wastewater into the primary Fenton oxidation reaction tank and add H2O2 for oxidation reaction; S2: injecting the industrial high-salt wastewater that has undergone oxidation reaction into a secondary Fenton oxidation reaction tank, and continuing to add H2O2 for oxidation reaction; S3: injecting the industrial high-salt wastewater after two oxidation reactions into the defluorination reaction tank, adding excess calcium chloride, and then adding flocculant PAM, stirring for 8 minutes and then allowing to settle for 20-40 minutes; S4: inject the supernatant in step S3 into the dechlorination reaction tank, add calcium aluminum salt to react for 3-4 hours, and add flocculant PAM to the reaction device at the same time; S5: inject the supernatant of step S4 into a flocculation sedimentation tank, add calcium oxide and flocculant PAM, stir and mix, introduce compressed air while stirring, stop stirring and aerating the wastewater after stirring for 25 minutes, and let it settle for 30-40 minutes; S6: the supernatant liquid of step S5 is injected into the coke powder adsorption tank, and the adsorption capacity of the coke powder is used to remove tiny organic matter and inorganic suspended particles in the wastewater, and the final effluent discharged from the coke powder adsorption tower is the treated effluent.

[0009] The present invention is further configured as follows: in step S1, pickling waste liquid is also added to the primary Fenton oxidation reaction tank under continuous stirring to control the pH of the high-salt wastewater in the primary Fenton oxidation reaction tank to 2.0-3.0.

[0010] The present invention is further configured as follows: 30% H2O2 is added in step S1, so that the concentration of H2O2 in the primary Fenton oxidation reaction tank is 1300-1500ppm; and the oxidation reaction time is 2.0-3.0h.

[0011] The present invention is further configured as follows: in step S2, 30% H2O2 is added under continuous stirring to make the concentration of H2O2 in the secondary Fenton reaction tank 650-750ppm; and the oxidation reaction time is 1.0-2.0h.

[0012] The present invention is further configured as follows: the calcium chloride in step S3 is added under continuous stirring, wherein the F - The reaction generates CaF2 precipitate; the concentration of the flocculant PAM is 2-3ppm.

[0013] The present invention is further configured as follows: in step S4, the ratio of calcium aluminum salt is CaO:NaAl O2=3.5-4.5:1; and the concentration of flocculant PAM is 2-3 ppm.

[0014] The present invention is further configured as follows: in step S5, the concentration of the flocculant PAM is 2-3 ppm, and the pH of the wastewater is controlled to be 10-12.

[0015] The present invention is further configured as follows: the coke powder used in step S6 is dry quenched coke powder from a chemical plant that has been activated at high temperature; without adjusting the pH value of the wastewater, the residence time of the wastewater in the coke powder adsorption tower is controlled to be 2.0-3.0 hours; and the particle size of the coke powder is 110-130 meshes.

[0016] The beneficial effects of the present invention are as follows: the treatment method disclosed in the present invention can effectively remove the refractory organic pollutants, fluoride and chloride ions in the high-salinity wastewater, so that the water quality of the treated high-salinity wastewater can meet the requirements of the comprehensive emission standard (DB21 / 1627-2008). At the same time, the metallurgical pickling waste liquid is added to the Fenton oxidation reaction tank, and the pickling waste liquid of the steel plant is recycled to the maximum extent, making full use of the waste acid resources and Fe in the pickling waste liquid. 2+ , replacing the traditional method of maintaining the Fenton oxidation reaction by adding acid and ferrous catalyst, greatly saving the operating cost of wastewater treatment. In addition, CDQ coke powder is a by-product of the coking process. Its application in wastewater treatment not only improves the final effluent quality and reduces the overall wastewater treatment cost, but also achieves the purpose of treating waste with waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A flow chart of the present invention is shown. DETAILED DESCRIPTION

[0018] Those skilled in the art can refer to the content of this article and appropriately improve the process parameters. It is particularly important to point out that all similar replacements and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and relevant personnel can modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0019] Example 1

[0020] The present invention proposes a low-cost method for treating industrial high-salt wastewater, comprising the following steps: S1: Inject industrial high-salt wastewater into the primary Fenton oxidation reaction tank, add pickling wastewater (mainly H + :6-7g / L,Fe 2+ :300-550g / L), control the pH value of the wastewater in the oxidation pond to 2.0-3.0; then add 30% H2O2 to make the concentration of H2O2 in the first-level Fenton oxidation reaction tank 1300-1500ppm. 2+ Under the catalytic action of , hydroxyl radicals with high oxidation sites are generated to strongly oxidize and degrade organic matter in the wastewater. The oxidation reaction time is controlled to be 2.0-3.0h under stirring; S2: inject the industrial high-salt wastewater after the oxidation reaction in step S1 into the secondary Fenton oxidation reaction tank. 2+ As a reaction catalyst, it can continuously play a catalytic reaction, so there is no need to re-introduce pickling waste liquid. Add 30% H2O2 under continuous stirring, and the amount of H2O2 added is half of the amount added to the primary Fenton oxidation reaction tank, so that the concentration of H2O2 in the secondary Fenton reaction tank is 650-750ppm, and the oxidation reaction time is controlled to be 1.0-2.0h, and the organic matter that has not been degraded in the primary Fenton oxidation reaction tank is further degraded and removed; S3: injecting the industrial high-salt wastewater after two oxidation reactions into the defluorination reaction tank, adding excess calcium chloride into the defluorination reaction tank under stirring, and removing the F - The reaction generates CaF2 precipitate, and then 2-3ppm of flocculant PAM is added while stirring. After stirring for 8 minutes, it is allowed to settle for 20-40 minutes. The CaF2 precipitate at the bottom enters the sludge treatment system; S4: Take the supernatant in step S3 and inject it into the defluorination reaction tank. Add calcium aluminum salt in a ratio of CaO:NaAlO2=3.5-4.5:1 under stirring. The reaction time is 3-4h. During the reaction, 2-3ppm of flocculant PAM is added to accelerate precipitation. The bottom precipitate enters the sludge treatment system. S5: remove the supernatant in step S4 and inject it into a flocculation sedimentation tank. Add calcium oxide and 2-3ppm flocculant PAM into the flocculation sedimentation tank under stirring, control the pH of the wastewater to be between 10-12, introduce compressed air while stirring, fully oxidize the divalent iron in the wastewater into ferric hydroxide that is easy to precipitate, stop stirring and aerating the wastewater after the stirring time reaches 25 minutes, let it settle for 30-40 minutes, and the precipitate at the bottom enters the sludge treatment system; S6: remove the supernatant in step S5 and inject it into a coke powder adsorption tank. The coke powder used is dry quenched coke powder from a chemical plant that has been activated at high temperature. Water enters the coke powder adsorption tank from the upper part and exits from the lower part. The adsorption ability of coke powder is used to remove tiny organic matter and inorganic suspended particles in the wastewater, further reducing the chromaticity and soluble COD content of the wastewater. Without adjusting the pH value of the wastewater, the residence time of the wastewater in the coke powder adsorption tower is controlled to be 2.0-3.0h, the coke powder particle size is 110-130 mesh, and the effluent from the coke powder adsorption tower is the effluent after final treatment.

[0021] Example 2

[0022] This embodiment treats high-salinity wastewater according to the treatment method described in Example 1, including the following steps: S1: First, the industrial salt wastewater is put into the primary Fenton oxidation reaction tank. Under continuous stirring, the pickling waste liquid is added to control the pH of the wastewater in the primary Fenton oxidation reaction tank to 2.5. Then, 30% H2O2 is added to make the concentration of H2O2 in the primary Fenton oxidation reaction tank 1300ppm. The oxidation reaction time is controlled to be 2.0h under stirring.

[0023] S2: Inject the wastewater from the primary Fenton oxidation reaction tank into the secondary Fenton reaction tank, add 30% H2O2 under constant stirring, so that the concentration of H2O2 in the secondary Fenton reaction tank is 650ppm, control the oxidation reaction time to 1.0h, and further remove the undegraded organic matter in the wastewater.

[0024] S3: The wastewater from the secondary staged oxidation reaction tank is injected into the defluorination reaction tank. Excess calcium chloride is added into the defluorination reaction tank under stirring. 2ppm flocculant PAM is added while stirring. After stirring for 8 minutes, it is allowed to settle for 20 minutes. The CaF2 precipitate at the bottom enters the sludge treatment system.

[0025] S4: Take the supernatant of step S3 and put it into the dechlorination reaction tank. Under stirring, the ratio of calcium aluminum salt is CaO:NaAl O2=3.5:1. The reaction time is 3h. During the reaction, 2ppm of flocculant PAM is added to accelerate precipitation. The bottom precipitate enters the sludge treatment system.

[0026] S5: Take the supernatant of step S4 and put it into a flocculation sedimentation tank. Add calcium oxide and 2ppm flocculant PAM into the flocculation sedimentation tank under stirring, control the pH of the wastewater to 10, and introduce compressed air while stirring to fully oxidize the divalent iron in the wastewater into ferric hydroxide that is easy to precipitate. After the stirring time reaches 25 minutes, stop stirring and aerating the wastewater, let it stand for 30 minutes, and the bottom precipitate enters the sludge treatment system.

[0027] S6: Take the supernatant of step S5 and put it into a coke powder adsorption tank. The coke powder used is the dry quenched coke powder of a chemical plant after high-temperature activation. Without adjusting the pH value of the wastewater, the residence time of the wastewater in the coke powder adsorption tower is controlled to be 2.0h, and the coke powder particle size is 110 meshes. The effluent from the coke powder adsorption tower is the effluent after final treatment.

[0028] Example 3

[0029] This embodiment treats high-salinity wastewater according to the treatment method described in Example 1, including the following steps: S1: First, the industrial salt wastewater is put into the primary Fenton oxidation reaction tank. Under continuous stirring, the pickling waste liquid is added to control the pH of the wastewater in the primary Fenton oxidation reaction tank to 2.5. Then, 30% H2O2 is added to make the concentration of H2O2 in the primary Fenton oxidation reaction tank 1400ppm. The oxidation reaction time is controlled to be 2.5h under stirring.

[0030] S2: Inject the wastewater from the primary Fenton oxidation reaction tank into the secondary Fenton reaction tank, add 30% H2O2 under constant stirring, so that the concentration of H2O2 in the secondary Fenton reaction tank is 700ppm, control the oxidation reaction time to 1.5h, and further remove the undegraded organic matter in the wastewater.

[0031] S3: The wastewater from the secondary staged oxidation reaction tank is injected into the defluorination reaction tank. Excess calcium chloride is added into the defluorination reaction tank under stirring. 2.5ppm flocculant PAM is added while stirring. After stirring for 8 minutes, it is allowed to settle for 30 minutes. The CaF2 precipitate at the bottom enters the sludge treatment system.

[0032] S4: Take the supernatant of step S3 and put it into the dechlorination reaction tank. Under stirring, the ratio of calcium aluminum salt is CaO:NaAl O2=4.0:1. The reaction time is 3.5h. During the reaction, 2.5ppm of flocculant PAM is added to accelerate precipitation. The bottom precipitate enters the sludge treatment system.

[0033] S5: Take the supernatant of step S4 and put it into a flocculation sedimentation tank. Add calcium oxide and 2.5ppm flocculant PAM into the flocculation sedimentation tank under stirring, control the pH of the wastewater to 11, and introduce compressed air while stirring to fully oxidize the divalent iron in the wastewater into ferric hydroxide that is easy to precipitate. After the stirring time reaches 25 minutes, stop stirring and aerating the wastewater, let it stand for 35 minutes, and the bottom precipitate enters the sludge treatment system.

[0034] S6: Take the supernatant of step S5 and put it into a coke powder adsorption tank. The coke powder used is the dry quenched coke powder of a chemical plant after high-temperature activation. Without adjusting the pH value of the wastewater, the residence time of the wastewater in the coke powder adsorption tower is controlled to be 2.5 hours, and the coke powder particle size is 120 meshes. The effluent from the coke powder adsorption tower is the effluent after final treatment.

[0035] Example 4

[0036] This embodiment treats high-salinity wastewater according to the treatment method described in Example 1, including the following steps: S1: First, the industrial salt wastewater is put into the primary Fenton oxidation reaction tank. Under continuous stirring, the pickling waste liquid is added to control the pH of the wastewater in the primary Fenton oxidation reaction tank to 3.0. Then, 30% H2O2 is added to make the concentration of H2O2 in the primary Fenton oxidation reaction tank 1500ppm. The oxidation reaction time is controlled to be 3.0h under stirring.

[0037] S2: Inject the wastewater from the primary Fenton oxidation reaction tank into the secondary Fenton reaction tank, add 30% H2O2 under constant stirring, so that the concentration of H2O2 in the secondary Fenton reaction tank is 750ppm, control the oxidation reaction time to 2.0h, and further remove the undegraded organic matter in the wastewater.

[0038] S3: The wastewater from the secondary staged oxidation reaction tank is injected into the defluorination reaction tank. Excess calcium chloride is added into the defluorination reaction tank under stirring. 3ppm of flocculant PAM is added while stirring. After stirring for 8 minutes, it is allowed to settle for 40 minutes. The CaF2 precipitate at the bottom enters the sludge treatment system.

[0039] S4: Take the supernatant of step S3 and put it into the dechlorination reaction tank. Under stirring, the ratio of calcium aluminum salt is CaO:NaAl O2=4.5:1. The reaction time is 4h. During the reaction, 3ppm of flocculant PAM is added to accelerate precipitation. The bottom precipitate enters the sludge treatment system.

[0040] S5: Take the supernatant of step S4 and put it into a flocculation sedimentation tank. Add calcium oxide and 3ppm flocculant PAM into the flocculation sedimentation tank under stirring, control the pH of the wastewater to 12, and introduce compressed air while stirring to fully oxidize the divalent iron in the wastewater into ferric hydroxide that is easy to precipitate. After the stirring time reaches 25 minutes, stop stirring and aerating the wastewater, let it stand for 40 minutes, and the bottom precipitate enters the sludge treatment system.

[0041] S6: Take the supernatant of step S5 and put it into a coke powder adsorption tank. The coke powder used is the dry quenched coke powder of a chemical plant after high-temperature activation. Without adjusting the pH value of the wastewater, the residence time of the wastewater in the coke powder adsorption tower is controlled to be 3.0 hours, and the coke powder particle size is 130 meshes. The effluent from the coke powder adsorption tower is the effluent after final treatment.

[0042] The pollutant removal effects of Examples 2-4 are shown in Table 1: Table 1 Removal rate (%) Example 2 Example 3 Example 4 COD 98.5 99.3 99.1 <![CDATA[F - ]]> 98.6 98.2 98.9 <![CDATA[Cl - ]]> 97.3 97.9 97.7

[0043] Referring to Table 1, it can be seen that after the above process, the industrial high-salinity wastewater has a COD removal rate of >98.5%, a fluoride removal rate of >98.2%, a chloride removal rate of >97.3%, and a effluent COD of <50 mg / l. - <10mg / l,Cl - <250mg / l, the effluent quality is stable and meets the standards and can be discharged directly.

[0044] In summary, the beneficial effects of the present invention are as follows: the treatment method disclosed in the present invention can effectively remove the refractory organic pollutants, fluoride and chloride ions in the high-salinity wastewater, so that the water quality of the treated high-salinity wastewater can meet the requirements of the comprehensive emission standard (DB21 / 1627-2008). At the same time, the metallurgical pickling waste liquid is added to the Fenton oxidation reaction tank, and the pickling waste liquid of the steel plant is recycled to the maximum extent, making full use of the waste acid resources and Fe in the pickling waste liquid. 2+ , replacing the traditional method of maintaining the Fenton oxidation reaction by adding acid and ferrous catalyst, greatly saving the operating cost of wastewater treatment. In addition, CDQ coke powder is a by-product of the coking process. Its application in wastewater treatment not only improves the final effluent quality and reduces the overall wastewater treatment cost, but also achieves the purpose of treating waste with waste.

[0045] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be within the scope of protection of the present invention.

Claims

1. A low-cost method for treating industrial high-salt wastewater, characterized in that: The following steps are included: S1: Inject industrial high-salt wastewater into the primary Fenton oxidation reaction tank and add H2O2 for oxidation reaction; S2: injecting the industrial high-salt wastewater that has undergone oxidation reaction into a secondary Fenton oxidation reaction tank, and continuing to add H2O2 for oxidation reaction; S3: injecting the industrial high-salt wastewater after two oxidation reactions into the defluorination reaction tank, adding excess calcium chloride, and then adding flocculant PAM, stirring for 8 minutes and then allowing to settle for 20-40 minutes; S4: inject the supernatant in step S3 into the dechlorination reaction tank, add calcium aluminum salt to react for 3-4 hours, and add flocculant PAM to the reaction device at the same time; S5: inject the supernatant of step S4 into a flocculation sedimentation tank, add calcium oxide and flocculant PAM, stir and mix, introduce compressed air while stirring, stop stirring and aerating the wastewater after stirring for 25 minutes, and let it settle for 30-40 minutes; S6: the supernatant liquid of step S5 is injected into the coke powder adsorption tank, and the adsorption capacity of the coke powder is used to remove tiny organic matter and inorganic suspended particles in the wastewater, and the final effluent discharged from the coke powder adsorption tower is the treated effluent.

2. The low-cost treatment method for industrial high-salt wastewater according to claim 1, characterized in that: In step S1, it is also necessary to add pickling waste liquid into the primary Fenton oxidation reaction tank under continuous stirring to control the pH of the high-salt wastewater in the primary Fenton oxidation reaction tank to 2.0-3.

0.

3. The low-cost treatment method for industrial high-salt wastewater according to claim 2 is characterized in that: In step S1, 30% H2O2 is added to make the concentration of H2O2 in the primary Fenton oxidation reaction tank 1300-1500ppm; the oxidation reaction time is 2.0-3.0h.

4. The low-cost treatment method for industrial high-salt wastewater according to claim 1 is characterized in that: Step S2: 30% H2O2 is added under continuous stirring to make the concentration of H2O2 in the secondary Fenton reaction tank 650-750ppm; the oxidation reaction time is 1.0-2.0h.

5. The low-cost treatment method for industrial high-salt wastewater according to claim 1, characterized in that: The calcium chloride in step S3 is added under constant stirring, wherein F - The reaction generates CaF2 precipitate; the concentration of the flocculant PAM is 2-3ppm.

6. The low-cost treatment method for industrial high-salt wastewater according to claim 1, characterized in that: In step S4, the ratio of calcium aluminum salt is CaO:NaAlO2=3.5-4.5:1; the concentration of flocculant PAM is 2-3ppm.

7. The low-cost treatment method for industrial high-salt wastewater according to claim 1, characterized in that: In step S5, the concentration of the flocculant PAM is 2-3 ppm, and the pH of the wastewater is controlled to be 10-12.

8. The low-cost treatment method for industrial high-salt wastewater according to claim 1, characterized in that: The coke powder used in step S6 is dry quenched coke powder from a chemical plant that has been activated at high temperature. Without adjusting the pH value of the wastewater, the residence time of the wastewater in the coke powder adsorption tower is controlled to be 2.0-3.0 hours; the particle size of the coke powder is 110-130 meshes.

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