Process for integrated treatment of contaminated groundwater based on internal circulation ozone contact reaction tower

Abstract

The application discloses a process for treating contaminated underground water based on an internal circulation ozone contact reaction tower, which comprises the following steps: S1, preliminary treatment; S2, ozone contact reaction; introducing the water to be treated into a water inlet of the tower body, and injecting ozone gas into an inner cylinder to promote the water flow in the inner cylinder to flow from bottom to top to the two filling layers and then to circulate back to the inner cylinder; S3, aeration treatment; and S4, sedimentation and filtration; the process for treating sewage by using the internal circulation ozone contact reaction tower can optimize the gas-liquid mass transfer effect, the flow state of ozone is smoother, the ozone utilization rate is increased by more than 25%, and the treatment effect on sewage can be improved through the setting of the whole process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment, in particular to a process for integrated treatment of contaminated groundwater based on an internal circulation ozone contact reaction tower. BACKGROUND

[0002] In recent years, many closed chemical enterprises will leave soil and groundwater pollution problems, when treating these contaminated soils, multi-phase extraction method will be used, multi-phase extraction (MPE) technology is a high-efficiency, large-area treatment, and in-situ remediation technology applicable to high-concentration contaminated land, through vacuum extraction means, the soil gas, groundwater and oil layer in the underground contaminated area are extracted to the ground for phase separation and treatment, to achieve the purpose of site remediation. Multi-phase extraction will get a lot of multi-phase extraction liquid, which contains low concentration of dissolved organic matter, has the characteristics of complex composition, large concentration fluctuation range, variable flow, and many difficult-to-degrade organic matters, which need to be treated before reuse or direct discharge into surface water body.

[0003] In the process of water treatment of multi-phase extraction liquid, advanced oxidation process is usually used; advanced oxidation process can produce free radicals with strong oxidizing properties, which have no selectivity to organic matter and can treat toxic and harmful wastewater. Advanced oxidation process includes Fenton method, photochemical oxidation method, electrochemical oxidation method, catalytic ozonation method, etc. Among them, catalytic ozonation process has the characteristics of high oxidation capacity, short treatment time, and small selectivity to organic matter, and the catalyst can form different oxidation mechanisms, which has strong adaptability to wastewater, and is a potential process for treating multi-phase extraction liquid.

[0004] At present, in the catalytic ozonation process, due to the poor ozone mass transfer effect in the traditional filler tower, the ozone utilization rate is low, which leads to a large ozone dosage in actual application, and the ozone preparation process consumes high energy, resulting in high cost of ozonation technology. According to the calculation results in the literature, the ozone transfer efficiency in the empty tower is less than 25%, which is low for water treatment; the internal circulation ozone contact reaction tower is a device for treating wastewater by using the strong oxidizing property of ozone, and the existing process for water treatment by using the internal circulation ozone contact reaction tower needs to be optimized to improve the effect of water treatment. SUMMARY

[0005] In order to solve the above problems, the present application provides a process for integrated treatment of contaminated groundwater based on an internal circulation ozone contact reaction tower.

[0006] A process for treating contaminated groundwater based on an internal circulation ozone contact reaction tower, the internal circulation ozone contact reaction tower comprising a tower body, two packing layers arranged inside the tower body for ozone catalysis, and an inner cylinder inside the tower body for reflux; comprising the following steps:

[0007] S1, preliminary treatment;

[0008] The contaminated groundwater is treated by an oil-water separation system to obtain oil and water to be treated, the oil is recovered, and then the obtained water to be treated is filtered, wherein the filtration uses a filter screen with a pore size of 0.45 μm; then the filtered water to be treated is subjected to coagulation treatment; the coagulation treatment is: polyaluminum chloride and polyacrylamide are added to the water to be treated at a ratio of 150-250 mg:8-15 mg:1 L, and then stirred at a speed of 150-200 rpm for 0.5-2 min, and then stirred at a speed of 70-90 rpm for 10 min and then separated by standing, to obtain the preliminary treated water to be treated;

[0009] S2, ozone contact reaction;

[0010] The preliminary treated water to be treated is introduced into the water inlet of the tower body at a flow rate of 1-5 m 3 / h, ozone gas is injected into the inner cylinder to promote the water flow in the inner cylinder to flow from bottom to top to the two packing layers, and then to circulate back to the inner cylinder, the ozone dosage is 200-700 mg / L·h, the circulating backflow water quantity is 50-80% of the water inlet water quantity, the backflow speed is 0.5-2 m / s, and the ozone contact reaction time is 20-40 min;

[0011] S3, aeration treatment;

[0012] After the ozone contact reaction is completed, the ozone is stopped and aeration treatment is performed, the aeration treatment flow rate is 0.5-2 L / min, and the aeration treatment time is 10-30 min;

[0013] S4, sedimentation and filtration;

[0014] The water after aeration treatment is introduced into a sedimentation tank, and after 12-24 h of sedimentation, the treatment is completed.

[0015] Explanation: The above method sets reasonable and scientific ozone contact parameters to increase the residence time of ozone in the packing layer, improve the mass transfer efficiency of ozone, reduce the energy consumption of the reaction tower, and improve the efficiency of catalytic degradation of wastewater, and through aeration treatment, ozone in the water can be removed to prevent ozone from causing new pollution to the water body.

[0016] Further, in the S2 ozone contact reaction, micro-nano bubble assisted ozone catalysis is adopted; the method of adopting micro-nano bubble assisted ozone catalysis comprises: before the ozone gas enters the inner circulating ozone contact reaction tower, the ozone gas is dispersed by a micro-nano bubble generator to generate micro-nano bubbles, and the generated micro-nano bubbles are injected into the inner cylinder; wherein the power of the micro-nano bubble generator is 50-200W, the micro-nano bubble gas flow is 0.5-2L / min, and the residence time of the ozone gas in the micro-nano bubble generator is 2-5min.

[0017] Description: The above-mentioned micro-nano bubble assisted ozone catalysis can significantly increase the solubility and contact area of ozone, and improve the oxidation efficiency; by integrating the micro-nano bubble technology into the treatment process of the inner circulating ozone contact reaction tower, the utilization rate of ozone and the removal efficiency of pollutants can be significantly improved, thereby improving the overall treatment effect.

[0018] Further, in the S1 preliminary treatment, the oil-water separation system comprises an oil-water separator, an oil liquid collection tank and a to-be-treated water collection tank.

[0019] Further, the oil-water separator adopts a gravity oil-water separator.

[0020] Description: The above-mentioned gravity oil-water separator has the advantages of simple structure, easy maintenance, energy saving and environmental protection, high separation efficiency, etc.

[0021] Further, in the oil-water separation process, 0.5-1mmol / L of a separation aid is added, and the separation aid is methyl methacrylate.

[0022] Description: As an aid for oil-water separation, methyl methacrylate can improve the separation efficiency, enhance the stability and environmental protection.

[0023] Further, a layer of catalyst is arranged on each of the two packing layers, the ratio of the spacing of the packing layers to the height of the reaction tower is 0.16-0.25, the catalyst on the lower packing layer is a spherical aluminum-based catalyst, and the catalyst on the upper packing layer is a vanadium-based catalyst, and the ratio of the dosing amount of the spherical aluminum-based catalyst and the vanadium-based catalyst to the reaction tower is both 500-800g:5L.

[0024] Description: The above-mentioned two layers of different types of catalysts may have different active sites and catalytic mechanisms, and the combined use can produce a synergistic effect to improve the removal efficiency of pollutants. The two-layer system using spherical aluminum-based catalyst and vanadium-based catalyst can provide a more comprehensive, efficient and stable water treatment solution, especially for complex and variable polluted water quality.

[0025] Further, the spherical aluminum-based catalyst adopts Co3O4 / Al2O3 catalyst, and the vanadium-based catalyst adopts V2O5 / TiO2 catalyst.

[0026] Description: The Co3O4 / Al2O3 catalyst has high catalytic activity, good dispersibility, stability and selectivity; the V2O5 / TiO2 catalyst has excellent oxidation performance, low-temperature activity, good thermal stability and large specific surface area; the Co3O4 / Al2O3 catalyst can improve the selectivity of pollutants in water treatment, and the V2O5 / TiO2 catalyst is suitable for strong oxidizing environment, and the combination of the two can have more excellent effect in water treatment.

[0027] Further, the preparation method of the Co3O4 / Al2O3 catalyst comprises:

[0028] First, the Al2O3 is pretreated by radio frequency plasma, the power of radio frequency plasma treatment is 50-200 W, and the treatment time is 5-10 min;

[0029] Take CoSO4 solution with a concentration of 0.5-1 mol / L, and add Al2O3 to the CoSO4 solution in a ratio of 1-2 g:2-5 mL, while adding ammonia water to adjust the pH to 7-9, the temperature is 60-80℃, and the reaction time is 2-4 h, to obtain a precipitate;

[0030] The precipitate is dried and placed under plasma, the power of plasma treatment is 100-500 W, Co(acac)2 gas with a flow rate of 10 ml / min is introduced for deposition, the deposition time is 5-20 min, and then the Co3O4 / Al2O3 catalyst is obtained by calcining at 300-500℃ for 2-3 h.

[0031] Description: The Co3O4 / Al2O3 catalyst obtained by the above method can increase the active sites on the surface of the carrier by plasma pretreatment, improve the adsorption capacity of the metal precursor, and avoid the multi-step and possible unevenness in the traditional precipitation process.

[0032] Further, the preparation method of the V2O5 / TiO2 catalyst comprises:

[0033] According to the ratio of 1-3 g:100 ml, ammonium metavanadate is dissolved in deionized water to form an ammonium metavanadate solution; then according to the ratio of 3-4 g:100 ml, titanium white powder is added to the prepared ammonium metavanadate solution, and stirred at a temperature of 40-60℃ for 2-4 h;

[0034] Then 5-15% of ammonium metavanadate by mass of ammonium tungstate is added and mixed to obtain a mixture, and the mixture is dried to completion at a temperature of 70-80 DEG C, and then calcined at a temperature of 400-500 DEG C for 2-3 hours to obtain the V2O5 / TiO2 catalyst.

[0035] It is illustrated that the V2O5 / TiO2 catalyst prepared by the above method has good stability and regeneration, can prolong the service life of the catalyst, and the catalyst is easy to regenerate, and can restore its activity by proper regeneration methods, such as thermal regeneration, chemical regeneration, etc.

[0036] The present application has the following beneficial effects:

[0037] The method of the present application sets reasonable and scientific ozone contact parameters and operation methods to improve the residence time of ozone in the filling layer, improve the mass transfer efficiency of ozone, reduce the energy consumption of the reaction tower, and improve the efficiency of catalytic degradation of wastewater. Through aeration treatment, ozone in water can be removed to prevent ozone from causing new pollution to water bodies. At the same time, ozone catalysis assisted by micro-nano bubbles can significantly increase the solubility and contact area of ozone, and improve the oxidation efficiency. By integrating the micro-nano bubble technology into the treatment process of the internal circulation ozone contact reaction tower, the utilization rate of ozone and the removal efficiency of pollutants can be significantly improved, thereby improving the overall treatment effect. In addition, the setting of the catalyst further improves the water treatment effect. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a graph of the comparison of the COD and TOC treatment effects of high-concentration wastewater in the embodiment of the present application (a: COD; b: TOC);

[0039] Figure 2 is a graph of the comparison of the treatment effects of characteristic pollutants of high-concentration wastewater in the embodiment of the present application;

[0040] Figure 3 is a graph of the comparison of the COD and TOC treatment effects of medium-concentration wastewater in the embodiment of the present application;

[0041] Figure 4 is a graph of the comparison of the treatment effects of characteristic pollutants of medium-concentration wastewater in the embodiment of the present application;

[0042] Figure 5 is a graph of the comparison of the COD and TOC treatment effects of low-concentration wastewater in the embodiment of the present application;

[0043] Figure 6 is a graph of the comparison of the treatment effects of characteristic pollutants of low-concentration wastewater in the embodiment of the present application; DETAILED DESCRIPTION

[0044] In order to further illustrate the mode adopted by the present application and the effects achieved, the technical solutions of the present application will be clearly and completely described below in conjunction with experiments.

[0045] Embodiment 1: A process for integrated treatment of contaminated groundwater based on an internal circulation ozone contact reaction tower, the internal circulation ozone contact reaction tower comprising a tower body, two filling layers arranged inside the tower body for ozone catalysis, and an inner cylinder inside the tower body for reflux; comprising the following steps:

[0046] S1, preliminary treatment;

[0047] The contaminated groundwater is treated by an oil-water separation system to obtain oil and water to be treated, the oil is recovered, and then the obtained water to be treated is filtered, wherein the filtration adopts a filter screen with a pore size of 0.45 μm; then the filtered water to be treated is subjected to coagulation treatment; the coagulation treatment is: polyaluminum chloride and polyacrylamide are added to the water to be treated at a ratio of 200 mg: 10 mg: 1 L, and then stirred at a speed of 160 rpm for 1 min, and then stirred at a speed of 80 rpm for 10 min and then separated by standing to obtain the preliminary treated water to be treated;

[0048] The oil-water separation system comprises an oil-water separator, an oil collection tank and a water to be treated collection tank.

[0049] The oil-water separator adopts a gravity oil-water separator.

[0050] In the oil-water separation process, 0.8 mmol / L of a separation aid is added, and the separation aid is methyl methacrylate;

[0051] A layer of catalyst is arranged on each of the two filling layers, the ratio of the distance between the filling layers to the height of the reaction tower is 0.20, the catalyst on the lower filling layer is a spherical aluminum-based catalyst, and the catalyst on the upper filling layer is a vanadium-based catalyst, the ratio of the dosages of the spherical aluminum-based catalyst and the vanadium-based catalyst to the reaction tower is both 600 g: 5 L;

[0052] The spherical aluminum-based catalyst is a Co3O4 / Al2O3 catalyst, and the vanadium-based catalyst is a V2O5 / TiO2 catalyst.

[0053] The preparation method of the Co3O4 / Al2O3 catalyst comprises:

[0054] First, Al2O3 is pretreated by radio frequency plasma, the power of the radio frequency plasma treatment is 100 W, and the treatment time is 7 min;

[0055] The CoSO4 solution with a concentration of 0.7 mol / L is taken, Al2O3 is added into the CoSO4 solution at a ratio of 1.5 g:4 mL, ammonia water is added dropwise to adjust the pH to 8, the temperature is 70℃, and the reaction time is 3 h to obtain a precipitate;

[0056] The precipitate is dried and placed under plasma, Co(acac)2 gas with a flow rate of 10 ml / min is introduced for deposition when the power is 300 W during plasma treatment, the deposition time is 10 min, and then the Co3O4 / Al2O3 catalyst is obtained by calcining at 400℃ for 2.5 h.

[0057] The preparation method of the V2O5 / TiO2 catalyst comprises:

[0058] According to a ratio of 2 g:100 ml, ammonium metavanadate is dissolved in deionized water to form an ammonium metavanadate solution; then according to a ratio of 3.2 g:100 ml, titanium white powder is added to the prepared ammonium metavanadate solution, and stirred at a temperature of 50℃ for 3 h;

[0059] Then 10% of the mass of ammonium metavanadate is added to ammonium tungstate and mixed to obtain a mixture, the mixture is dried to completion at a temperature of 75℃, and then the V2O5 / TiO2 catalyst is obtained by calcining at a temperature of 450℃ for 2.5 h.

[0060] S2, ozone contact reaction;

[0061] The water to be treated after the preliminary treatment is introduced into the water inlet of the tower body at a flow rate of 3 m 3 / h, ozone gas is injected into the inner cylinder to promote the water flow in the inner cylinder to flow from bottom to top to the two filling layers and then circulate back to the inner cylinder, the ozone dosage is 500 mg / L·h, the circulating backflow water amount is 60% of the water amount at the water inlet, the backflow speed is 1 m / s, and the ozone contact reaction time is 30 min;

[0062] In the above ozone contact reaction, micro-nano bubble assisted ozone catalysis is adopted; the method of adopting micro-nano bubble assisted ozone catalysis comprises: before the ozone gas enters the inner circulating ozone contact reaction tower, a micro-nano bubble generator is used to generate micro-nano bubbles by dispersing the ozone gas, and the generated micro-nano bubbles are injected into the inner cylinder; wherein the power of the micro-nano bubble generator is 100 W, the micro-nano bubble gas flow rate is 0.8 L / min, and the residence time in the micro-nano bubble generator is 3 min;

[0063] S3, aeration treatment;

[0064] After the ozone contact reaction is completed, the ozone is stopped and aeration treatment is performed, the flow rate of the aeration treatment is 1 L / min, and the aeration treatment time is 20 min;

[0065] S4, sedimentation filtration;

[0066] The water after the aeration treatment is introduced into a sedimentation tank, filtered after sedimentation for 15 h, and the treatment is completed.

[0067] Example 2: The difference between this example and example 1 is that the treatment parameters in S1 are different, 0.5 mmol / L of a separation aid is added in the oil-water separation process, the separation aid is methyl methacrylate, and the coagulation treatment is: polyaluminum chloride and polyacrylamide are added to the water to be treated at a ratio of 150 mg: 15 mg: 1 L, then stirred at a speed of 150 rpm for 2 min, and then stirred at a speed of 70 rpm for 10 min before standing and separating to obtain the water to be treated after preliminary treatment.

[0068] Example 3: The difference between this example and example 1 is that the treatment parameters in S1 are different, 1 mmol / L of a separation aid is added in the oil-water separation process, the separation aid is methyl methacrylate, and the coagulation treatment is: polyaluminum chloride and polyacrylamide are added to the water to be treated at a ratio of 250 mg: 8 mg: 1 L, then stirred at a speed of 200 rpm for 0.5 min, and then stirred at a speed of 90 rpm for 10 min before standing and separating to obtain the water to be treated after preliminary treatment.

[0069] Example 4: The difference between this example and example 1 is that the preparation component parameters of the Co3O4 / Al2O3 catalyst are different, a CoSO4 solution with a concentration of 0.5 mol / L is taken, Al2O3 is added to the CoSO4 solution at a ratio of 1 g: 2 mL, and ammonia water is added dropwise to adjust the pH to 9.

[0070] Example 5: The difference between this example and example 1 is that the preparation component parameters of the Co3O4 / Al2O3 catalyst are different, a CoSO4 solution with a concentration of 1 mol / L is taken, Al2O3 is added to the CoSO4 solution at a ratio of 2 g: 5 mL, and ammonia water is added dropwise to adjust the pH to 7.

[0071] Example 6: The difference between this example and example 1 is that the preparation method parameters of the Co3O4 / Al2O3 catalyst are different, first, the Al2O3 is pretreated by radio frequency plasma, the power of the radio frequency plasma treatment is 50 W, and the treatment time is 10 min;

[0072] Take the concentration of CoSO4 solution, Al2O3 is added to the CoSO4 solution, while adding ammonia, the temperature is 60℃, the reaction time is 2h, the precipitate is obtained;

[0073] The precipitate is dried and put into plasma, the power of plasma treatment is 100W, Co(acac)2 gas with a flow rate of 10ml / min is introduced for deposition, the deposition time is 5min, then the Co3O4 / Al2O3 catalyst is obtained by calcining at 300℃ for 2h.

[0074] Example 7: The difference between this example and example 1 is that the preparation method parameters of the Co3O4 / Al2O3 catalyst are different, first, the Al2O3 is pretreated by radio frequency plasma, the power of radio frequency plasma treatment is 200W, the treatment time is 5min;

[0075] Take the concentration of CoSO4 solution, Al2O3 is added to the CoSO4 solution, while adding ammonia, the temperature is 80℃, the reaction time is 4h, the precipitate is obtained;

[0076] The precipitate is dried and put into plasma, the power of plasma treatment is 100-500W, Co(acac)2 gas with a flow rate of 10ml / min is introduced for deposition, the deposition time is 20min, then the Co3O4 / Al2O3 catalyst is obtained by calcining at 500℃ for 3h.

[0077] Example 8: The difference between this example and example 1 is that the preparation component parameters of the V2O5 / TiO2 catalyst are different, according to the ratio of 3g:100ml, ammonium metavanadate is dissolved in deionized water to form an ammonium metavanadate solution; then according to the ratio of 4g:100ml, titanium dioxide is added to the prepared ammonium metavanadate solution; then 5% of the mass of ammonium metavanadate is added to tungsten acid and mixed.

[0078] Example 9: The difference between this example and example 1 is that the preparation component parameters of the V2O5 / TiO2 catalyst are different, according to the ratio of 1g:100ml, ammonium metavanadate is dissolved in deionized water to form an ammonium metavanadate solution; then according to the ratio of 3g:100ml, titanium dioxide is added to the prepared ammonium metavanadate solution; then 15% of the mass of ammonium metavanadate is added to tungsten acid and mixed.

[0079] Example 10: The difference between this example and Example 1 is that the preparation method parameters of the V2O5 / TiO2 catalyst are different. Ammonium metavanadate is dissolved in deionized water to form an ammonium metavanadate solution; titanium dioxide is added to the prepared ammonium metavanadate solution, stirred at a temperature of 60°C for 2h; then ammonium tungstate is added and mixed to obtain a mixture, and the mixture is dried to completion at a temperature of 70°C, followed by calcination at a temperature of 400°C for 2h to obtain a V2O5 / TiO2 catalyst.

[0080] Example 11: The difference between this example and Example 1 is that the preparation method parameters of the V2O5 / TiO2 catalyst are different. Ammonium metavanadate is dissolved in deionized water to form an ammonium metavanadate solution; titanium dioxide is added to the prepared ammonium metavanadate solution, stirred at a temperature of 40°C for 4h; then ammonium tungstate is added and mixed to obtain a mixture, and the mixture is dried to completion at a temperature of 80°C, followed by calcination at a temperature of 500°C for 3h to obtain a V2O5 / TiO2 catalyst.

[0081] Example 12: The difference between this example and Example 1 is that the flow rate of the water to be treated in S2 is different. The water to be treated is introduced into the water inlet of the tower body at a flow rate of 1m 3 / h, and the amount of the circulating reflux water is 80% of the amount of the water inlet water.

[0082] Example 13: The difference between this example and Example 1 is that the flow rate of the water to be treated in S2 is different. The water to be treated is introduced into the water inlet of the tower body at a flow rate of 5m 3 / h, and the amount of the circulating reflux water is 50% of the amount of the water inlet water.

[0083] Example 14: The difference between this example and Example 1 is that the ozone dosage in S2 is different, and the ozone dosage is 200mg / L·h.

[0084] Example 15: The difference between this example and Example 1 is that the ozone dosage in S2 is different, and the ozone dosage is 700mg / L·h.

[0085] Example 16: The difference between this example and Example 1 is that the reflux speed in S2 is 0.5-2m / s; and the ozone contact reaction time is 20min.

[0086] Example 17: The difference between this example and Example 1 is that the reflux speed in S2 is 0.5-2m / s; and the ozone contact reaction time is 40min.

[0087] Example 18: The difference between this example and Example 1 is that the micro-nano bubble generator power is 50 W, the micro-nano bubble gas flow is 2 L / min, and the residence time is 2 min.

[0088] Example 19: The difference between this example and Example 1 is that the micro-nano bubble generator power is 200 W, the micro-nano bubble gas flow is 0.5 L / min, and the residence time is 5 min.

[0089] Example 20: The difference between this example and Example 1 is that the flow rate of aeration treatment in S3 is 0.5 L / min, and the aeration treatment time is 10 min; and the filtration after precipitation for 12 h in S4.

[0090] Example 21: The difference between this example and Example 1 is that the flow rate of aeration treatment in S3 is 2 L / min, and the aeration treatment time is 30 min; and the filtration after precipitation for 24 h in S4.

[0091] Example 22: The difference between this example and Example 1 is that the ratio of the spacing of the packing layer to the height of the reaction tower is 0.16, the catalyst on the lower packing layer is a spherical aluminum-based catalyst, the catalyst on the upper packing layer is a vanadium-based catalyst, and the ratio of the dosing amount of the aluminum-based catalyst and the vanadium-based catalyst to the reaction tower is 500 g:5 L.

[0092] Example 23: The difference between this example and Example 1 is that the ratio of the spacing of the packing layer to the height of the reaction tower is 0.25, the catalyst on the lower packing layer is a spherical aluminum-based catalyst, the catalyst on the upper packing layer is a vanadium-based catalyst, and the ratio of the dosing amount of the aluminum-based catalyst and the vanadium-based catalyst to the reaction tower is 800 g:5 L.

[0093] Experimental Example: The description of this experimental example is based on the description of Example 1, and is intended to illustrate the actual application effect of the present application.

[0094] Experimental Example:

[0095] I. The optimized internal circulation ozone contact reaction tower and the traditional ozone reaction tower were used to treat the same wastewater, and the method of Example 1 was used, the aeration flow rate was 900 mL / min, the concentration of O3 was 45 g / m 3 , intermittent treatment for 60 min, and then continuous treatment for 120 min, the ozone dosage was 600 mg / L·h. The treatment effect of adding catalyst and not adding catalyst was investigated, and the dosing amount of the catalyst was 800 g, and the volume of the reaction tower was 4.7 L.

[0096] The experimental water is a pesticide factory site of multiple extraction liquid wastewater, the high concentration of COD wastewater is 2000mg / L. Compare the removal effect of COD, TOC and characteristic pollutants, such as Figure 1 shown.

[0097] Depend on Figure 1 It is known that for high-concentration wastewater, when the tower is empty or with a catalyst added, the internal circulation ozone reactor shows significantly improved COD and TOC removal efficiency compared to conventional ozone reactors after 60 minutes of treatment, and the removal rate of characteristic pollutants is also significantly improved. During the subsequent two HRT continuous treatment processes, the treatment efficiency of the internal circulation ozone reactor decreased slightly, but the improvement in ozone treatment efficiency compared to conventional ozone reactors was still significant.

[0098] Under the empty tower condition, after 60 minutes of treatment and an ozone dosage of 600 mg / (L·h), the ICR treated wastewater achieved a COD degradation of 440 mg / L, a 57.14% increase over the OR, and a TOC degradation of 59.4 mg / L, a 65% increase over the OR. After two HRT continuous flow treatments, the ICR achieved a COD degradation of 430 mg / L and a TOC degradation of 58.6 mg / L every 60 minutes, respectively. The ICR treatment effect was still significantly improved compared to the OR treatment effect. The ICR achieved a COD removal efficiency of 0.72 mg for every 1 mg of ozone, while the OR removed 0.48 mg of COD, a significant improvement.

[0099] With the addition of a catalyst, the ICR treated wastewater at an ozone dosage of 600 mg / (L·h) for 60 minutes, achieving a COD degradation of 532 mg / L, a 60.98% increase over the OR, and a TOC degradation of 66.6 mg / L, a 66.7% increase over the OR. After two HRT continuous flow treatments, the ICR achieved COD degradation of 520 mg / L and TOC degradation of 58.1 mg / L, respectively, every 60 minutes. The ICR treatment performance remained significantly improved compared to the OR treatment. The ICR achieved a COD removal efficiency of 0.87 mg for every 1 mg of ozone, while the OR treatment achieved 0.51 mg, a significant improvement.

[0100] Adding a catalyst further increases the pollutant removal rate of ICR compared to OR. This is because the internal circulation function of the ICR allows for more complete contact between the catalyst and ozone, and increases the catalyst's pores. Furthermore, the continuous ICR's improvement in pollutant removal rate decreases compared to the intermittent type. This is because continuous operation increases the turbulence of the water flow within the OR, improving the treatment effect.

[0101] The degradation of some characteristic pollutants (dichloromethane, chloroform, benzene, chlorobenzene, toluene) in the multi-phase extraction liquid in the catalytic ozonation process was analyzed, and the experimental results are shown in Table 2. Figure 2

[0102] (a: ozone dosage 600 mg / (L·h) without catalyst; b: ozone dosage 600 mg / (L·h) with catalyst)

[0103] In the ICR system, after 2 HRT continuous treatment at an ozone dosage of 600 mg / (L·h), the removal rates of chlorobenzene, dichloromethane, benzene, toluene, and chloroform were 93.7%, 94.3%, 84.6%, 84.6%, and 83.2% respectively without catalyst, which were 17.1%, 19.7%, 19%, 19.4%, and 15.3% higher than those of OR. With catalyst, the removal rates of chlorobenzene, dichloromethane, benzene, toluene, and chloroform were 93.6%, 96.6%, 94.3%, 85.1%, and 87%, which were 14.4%, 19.7%, 16%, 16.1%, and 18.7% higher than those of OR. In the continuous flow operation, the removal rates of the characteristic pollutants of ICR were significantly higher than the COD removal rate, because ozone converted the refractory pollutants into easily degradable substances by destroying their structures. In addition, the removal rate of ICR for the characteristic pollutants decreased compared with OR, which was due to the influence of the backflow condition of the internal circulation system in the continuous flow operation, and the good turbulent flow state in the reaction tower caused by the increased water flow disturbance in the OR.

[0104] Although dichloromethane and chloroform did not reach the Class III standard of underground water after 120 min of continuous flow treatment, the degradation rate of dichloromethane and chloroform in the internal circulation ozone reaction tower was much faster than that in the ordinary ozone reaction tower, and the reaction time could be appropriately extended to achieve complete degradation in the actual process. The initial concentration of benzene was 222 mg / L, which decreased to 12 mg / L after 120 min of continuous flow treatment in the internal circulation ozone reaction tower system, and the Class III standard of underground water could be reached by extending the time. The initial concentration of chlorobenzene was about 157 mg / L, and the concentration was 31 mg / L and 9.9 mg / L respectively after 120 min of continuous flow treatment in the ordinary ozone reaction tower and the internal circulation ozone reaction tower, reaching the Class II standard of underground water. The initial concentration of toluene was about 74.68 mg / L, and the concentration was 16.7 mg / L and 11.1 mg / L respectively after 120 min of continuous flow treatment in the ordinary ozone reaction tower and the internal circulation ozone reaction tower, reaching the Class II standard of underground water. In the removal of the characteristic pollutants, the oxidation efficiency of the internal circulation ozone reaction tower system was much higher than that of the ordinary ozone reaction tower system.

[0105] ​Through the treatment results of high-concentration wastewater under the above-mentioned continuous working conditions, it can be found that the use and setting of the reaction tower in the method of this embodiment (i.e., the design of the ozone oxidation catalysis method) and the selection of the catalyst have better effects than those in the prior art. Therefore, it can be seen that the process method in the embodiment of the present invention is more preferred (the same applies to the treatment results of the following two and three for different polluted wastewaters).

[0106] 2. Comparative study on the treatment effect of medium-concentration wastewater under continuous conditions

[0107] The optimized internal circulation ozone contact reaction tower and the ordinary ozone reaction tower were used to treat the same wastewater. The aeration flow rate was 600 mL / min and the concentration of 45 g / m 3 O3, intermittent treatment for 60 minutes, then continuous treatment for 120 minutes, with an ozone dosage of 400 mg / (L·h). The treatment effects with and without the addition of a catalyst were investigated. The catalyst dosage was 800 g. The experimental water was wastewater from a pesticide factory with a medium concentration of COD of 500 mg / L. The removal effects of COD, TOC, and characteristic pollutants were compared, such as Figure 3 shown.

[0108] Depend on Figure 3 It is known that for medium-concentration wastewater, when the tower is empty or with a catalyst added, the internal circulation ozone reactor has significantly improved the COD and TOC removal efficiency compared to the ordinary ozone reactor after 60 minutes of treatment, and the removal rate of characteristic pollutants has also been significantly improved. During the subsequent two HRT continuous treatment processes, the treatment efficiency of the internal circulation ozone reactor decreased slightly, but the improvement in treatment efficiency compared to the ordinary ozone reactor was still significant.

[0109] ICR treated wastewater for 60 minutes at an ozone dosage of 400 mg / (L·h). Under the empty tower conditions, the COD removal rate was 39.51%, a 9.97% increase over the OR, and the TOC degradation rate was 39.84%, a 10.59% increase over the OR. After two HRTs of continuous treatment, the ICR COD removal rate was 38.68% and the TOC degradation rate was 39.60% per 60 minutes. With the addition of a catalyst, the COD removal rate was 42.62%, an 11.82% increase over the OR, and the TOC degradation rate was 40.71%, an 11.14% increase over the OR. After two HRTs of continuous treatment, the ICR COD removal rate was 41.77% and the TOC degradation rate was 40.55% per 60 minutes, showing significant improvement over the OR. The improvement in pollutant removal efficiency by ICR compared to OR decreased due to the decrease in initial pollutant concentration, which is attributed to the limited reaction intensity caused by the pollutant concentration.

[0110] The degradation of some characteristic pollutants (dichloromethane, chloroform, benzene, chlorobenzene, toluene) in the multi-phase extraction liquid in the catalytic ozonation process was analyzed, and the experimental results are shown in Table 2. Figure 4

[0111] (a: ozone dosage 400 mg / (L·h) without catalyst; b: ozone dosage 400 mg / (L·h) with catalyst)

[0112] In the ICR system, after 2 HRT continuous treatment at an ozone dosage of 400 mg / (L·h), the removal rates of chlorobenzene, dichloromethane, benzene, toluene, and chloroform were 97.7%, 98.9%, 98.2%, 98.4%, and 99% respectively without catalyst, which was 3.6%, 1.4%, 2.2%, 3.3%, and 3.1% higher than OR. With catalyst, the removal rates of chlorobenzene, dichloromethane, benzene, toluene, and chloroform were 98%, 98.9%, 98.4%, 98.8%, and 99.1% respectively, which was 3.2%, 0.8%, 2.1%, 3.1%, and 2.5% higher than OR. Due to the low initial concentration, the removal rates of the characteristic pollutants in the continuous ICR and OR reached more than 95%.

[0113] After 120 min of continuous flow treatment in the ordinary ozone reaction tower and the internal circulation ozone reaction tower systems, chloroform reached the groundwater class II and class I standards respectively. The initial concentration of dichloromethane was 920 mg / L, which was reduced to 2.05 mg / L after 120 min of continuous flow treatment in the internal circulation ozone reaction tower system, reaching the groundwater class II standard. The initial concentration of benzene was 222 mg / L, which was reduced to 0.37 mg / L after 120 min of continuous flow treatment in the internal circulation ozone reaction tower system, reaching the groundwater class I standard. The initial concentration of chlorobenzene was about 157 mg / L, which was 0.446 mg / L and 0.566 mg / L respectively after 120 min of continuous flow treatment in the ordinary ozone reaction tower and the internal circulation ozone reaction tower systems, reaching the groundwater class I and class II standards respectively. The initial concentration of toluene was about 74.68 mg / L, which was 0.14 mg / L and 0.11 mg / L respectively after 120 min of continuous flow treatment in the ordinary ozone reaction tower and the internal circulation ozone reaction tower systems, reaching the groundwater class I standard. In the removal of characteristic pollutants, the oxidation efficiency of the internal circulation ozone reaction tower system was higher than that of the ordinary ozone reaction tower system.

[0114] III. Comparative study on the treatment effect of low-concentration wastewater under continuous working conditions

[0115] The optimized internal circulation ozone contact reaction tower and the ordinary ozone reaction tower were used to treat the same wastewater, and the aeration flow rate was 600 mL / min with a concentration of 45 g / m 3 ​O3, intermittent treatment for 60 minutes, and then continuous treatment for 120 min, with an ozone dosage of 400 mg / (L·h). The treatment effects with and without catalysts were investigated, respectively. The catalyst dosage was 800 g, and the experimental water was a multi-extraction liquid wastewater from a pesticide factory site. The COD of the high-concentration wastewater was 200 mg / L. The removal effects of COD, TOC, and characteristic pollutants were compared, as shown in Figure 5 .

[0116] It is known that for low-concentration wastewater, in the case of an empty tower or with catalysts, the removal efficiency of COD, TOC, and characteristic pollutants in the internal circulation ozone reaction tower is significantly improved compared with the ordinary ozone reaction tower when the treatment time is 60 min. In the subsequent 2 HRT continuous flow treatment processes, the treatment efficiency of the internal circulation ozone reaction tower has a slight decline, and the treatment efficiency improvement compared with the ordinary ozone reaction tower is still obvious. Figure 5 When the treatment time is 60 min and the ozone dosage is 400 mg / (L·h), the wastewater is treated by ICR. In the case of an empty tower, the COD removal rate is 49.59%, which is 17.69% higher than that of OR. The TOC degradation amount is 45.67%, which is 17.07% higher than that of OR. After 2 HRT continuous flow treatment, the COD removal rate of ICR is 47.96% every 60 min, and the TOC degradation amount is 46.11%. In the case of adding catalysts, the COD removal rate is 24.02% higher than that of OR, and the TOC degradation amount is 56.13%, which is 16.46% higher than that of OR. After 2 HRT continuous flow treatment, the COD removal rate of ICR is 60.74% every 60 min, and the TOC degradation amount is 54.89%. The treatment effect of ICR is still significantly improved compared with OR. In the continuous working condition, since the catalyst in ICR contacts ozone more fully, the COD removal rate is improved more greatly.

[0117] The degradation of some characteristic pollutants (dichloromethane, chloroform, benzene, chlorobenzene, and toluene) in the multi-phase extraction liquid in the catalytic ozonation process was analyzed, and the experimental results are shown in

[0118] . Figure 6

[0119] (a: ozone dosage 400 mg / (L·h) without catalysts; b: ozone dosage 400 mg / (L·h) with catalysts)

[0120] ​In the ICR system, after 2 HRT continuous treatment with ozone dosage of 600 mg / (L·h), without catalyst, the removal rates of chlorobenzene, dichloromethane, benzene, toluene and chloroform were 99.8%, 99.8%, 99.4%, 99.6% and 99.8% respectively, which were 1.6%, 0.6%, 0.4%, 0.5% and 0.7% higher than OR. With catalyst, the removal rates of chlorobenzene, dichloromethane, benzene, toluene and chloroform were 99.4, 99.8, 99.8, 99.5 and 99.6 respectively, which were 0.9%, 0.7%, 0.5%, 0.4% and 0.5% higher than OR. The removal rates of ICR and OR for the characteristic pollutants were both above 98%.

[0121] The initial concentration of chlorobenzene was 15.2 mg / L, which was reduced to 0.112 mg / L after 30 minutes of reaction in the internal circulation ozone reaction tower system, reaching the Class I standard of groundwater. The initial concentration of dichloromethane was 368 mg / L, which was reduced to 0.66 mg / L after 30 minutes of reaction in the internal circulation ozone reaction tower system, reaching the Class I standard of groundwater. The initial concentration of benzene was 21.6 mg / L, which was reduced to 0.128 mg / L after 30 minutes of reaction in the internal circulation ozone reaction tower system, reaching the Class I standard of groundwater. The initial concentration of chloroform was about 248.8 mg / L, which was reduced to 1.4 mg / L and 0.516 mg / L respectively after 30 minutes of reaction in the ordinary ozone reaction tower and the internal circulation ozone reaction tower systems, reaching the Class II standard of groundwater. The initial concentration of toluene was about 7.2 mg / L, which was reduced to 0.072 mg / L and 0.04 mg / L respectively after 30 minutes of reaction in the ordinary ozone reaction tower and the internal circulation ozone reaction tower systems, reaching the Class I standard of groundwater. In the removal of characteristic pollutants, the oxidation efficiency of the internal circulation ozone reaction tower system was higher than that of the ordinary ozone reaction tower system.

[0122] Four, comparative study on treatment effect of low concentration wastewater by different treatment methods

[0123] Comparative Example 1: The difference from Example 1 is that it is not treated by micro-nano bubble assisted ozone catalysis, but directly uses the micro-porous diffuser used in the traditional process.

[0124] Comparative Example 2: The difference from Example 1 is that no separation aid is added for the separation process.

[0125] Comparative Example 3: The difference from Example 1 is that the catalysts in the two packing layers are the same, both of which are V2O5 / TiO2 catalysts.

[0126] Comparative Example 4: The difference from Example 1 is that the catalysts in the two packing layers are both commercially available Co3O4 / Al2O3 catalyst and V2O5 / TiO2 catalyst.

[0127] The comparative examples 1-4 of example 1 were compared, as shown in Table 1.

[0128] Table 1: Experimental results of different treatment methods on low-concentration wastewater treatment effect

[0129]

[0130]

[0131] From Table 1, it can be seen that the comparative example 1 and the comparative example 1 can be seen that the method in example 1 is more preferred, which may be because the method in example 1 is treated by micro-nano bubble assisted ozone catalysis, which significantly increases the solubility and contact area of ozone, improves the oxidation efficiency; by integrating the micro-nano bubble technology into the treatment process of the internal circulation ozone contact reaction tower, the utilization rate of ozone and the removal efficiency of pollutants can be significantly improved, thereby improving the overall treatment effect.

[0132] Comparative example 1 and comparative example 2 can be seen that the method of adding separation aid in example 1 is more preferred, the reason is that after adding the separation aid, the oil and water in the sewage are separated more thoroughly, the content of pollutants in the water to be treated is easier to remove, which can avoid the problem that the pollutants exist in the form of small oil droplets in comparative example 2, resulting in poor water treatment effect;

[0133] Comparative example 1, comparative example 3 and comparative example 4 can be found that the method of catalyst design in example 1 is more preferred, which can make the two catalysts have a certain synergistic effect in addition to their respective functions, which can further improve the catalytic effect and improve the water treatment effect.

Claims

1. Process for the integrated treatment of contaminated groundwaters based on an internal circulation ozone contact reactor tower, characterized in that, The inner circulation ozone contact reaction tower comprises a tower body, two filling layers arranged inside the tower body for ozone catalysis, and an inner cylinder inside the tower body for reflux; and comprises the following steps: S1, preliminary treatment; The contaminated groundwater is treated by an oil-water separation system to obtain oil liquid and water to be treated, the oil liquid is recovered, and then the obtained water to be treated is filtered, wherein the filtration adopts a filter screen with a pore size of 0.45 μm; then the filtered water to be treated is subjected to coagulation treatment; the coagulation treatment is that polyaluminum chloride and polyacrylamide are added to the water to be treated in a ratio of 150-250 mg:8-15 mg:1 L, and then stirred at a speed of 150-200 rpm for 0.5-2 min, and then stirred at a speed of 70-90 rpm for 10 min and then separated after standing, to obtain the water to be treated after preliminary treatment; S2, ozone contact reaction; The primary treated water to be treated is introduced into the water inlet of the tower body at a flow rate of 1-5 m 3 / h, ozone gas is injected into the inner cylinder to promote the water flow in the inner cylinder to flow from bottom to top to the two packing layers and then to circulate back to the inner cylinder, the ozone dosage is 200-700 mg / L·h, the circulating backflow water quantity is 50-80% of the water quantity at the water inlet, the backflow speed is 0.5-2 m / s, the ozone contact reaction time is 20-40 min, a layer of catalyst is arranged on each of the two packing layers, the ratio of the spacing of the packing layers to the height of the reaction tower is 0.16-0.25, the catalyst on the lower packing layer is a spherical aluminum-based catalyst, the catalyst on the upper packing layer is a vanadium-based catalyst, the ratio of the dosage of the spherical aluminum-based catalyst and the vanadium-based catalyst to the reaction tower is both 500-800 g:5 L. The spherical aluminum-based catalyst adopts Co3O4 / Al2O3 catalyst, and the vanadium-based catalyst adopts V2O5 / TiO2 catalyst; the preparation method of the Co3O4 / Al2O3 catalyst comprises: First, the Al2O3 is pretreated by radio frequency plasma, the power of the radio frequency plasma treatment is 50-200 W, and the treatment time is 5-10 min; Take a CoSO4 solution with a concentration of 0.5-1 mol / L, add Al2O3 to the CoSO4 solution in a ratio of 1-2 g:2-5 mL, and drop ammonia water to adjust the pH to 7-9, the temperature is 60-80℃, and the reaction time is 2-4 h, to obtain a precipitate; The precipitate is dried and placed under plasma, Co(acac)2 gas with a flow rate of 10 ml / min is introduced for deposition, the deposition time is 5-20 min, and then the Co3O4 / Al2O3 catalyst is obtained by calcining at 300-500℃ for 2-3 h; S3, aeration treatment; After the ozone contact reaction is completed, the ozone is stopped and aeration treatment is performed, the flow rate of the aeration treatment is 0.5-2 L / min, and the aeration treatment time is 10-30 min; S4, sedimentation and filtration; The water after aeration treatment is introduced into a sedimentation tank, and the treatment is completed after 12-24 h of sedimentation.

2. The process for integrated treatment of contaminated groundwater based on internal circulation ozone contact reaction tower according to claim 1, characterized in that, In the ozone contact reaction S2, micro-nano bubble assisted ozone catalysis is adopted; the method of micro-nano bubble assisted ozone catalysis comprises: before the ozone gas enters the inner circulation ozone contact reaction tower, the ozone gas is dispersed by a micro-nano bubble generator to generate micro-nano bubbles, and the generated micro-nano bubbles are injected into the inner cylinder; wherein the power of the micro-nano bubble generator is 50-200 W, the flow rate of the micro-nano bubble gas is 0.5-2 L / min, and the residence time of the ozone gas in the micro-nano bubble generator is 2-5 min.

3. The process for integrated treatment of contaminated groundwater based on internal circulation ozone contact reaction tower according to claim 1, characterized in that, In the preliminary treatment S1, the oil-water separation system comprises an oil-water separator, an oil liquid collection tank, and a water to be treated collection tank.

4. The process for integrated treatment of contaminated groundwater based on internal circulation ozone contact reaction tower according to claim 3, characterized in that, The oil-water separator adopts a gravity oil-water separator.

5. The process for integrated treatment of contaminated groundwater based on internal circulation ozone contact reaction tower as claimed in claim 3 wherein, The oil-water separation process adds 0.5-1mmol / L of a separation aid, which is methyl methacrylate.

6. The process for integrated treatment of contaminated groundwater based on internal circulation ozone contact reaction tower as claimed in claim 1 wherein, The preparation method of the V2O5 / TiO2 catalyst comprises the following steps: According to the ratio of 1-3g: 100ml, ammonium metavanadate is dissolved in deionized water to form an ammonium metavanadate solution; then according to the ratio of 3-4g: 100ml, titanium white powder is added to the prepared ammonium metavanadate solution, and stirred at a temperature of 40-60 DEG C for 2-4h; Then 5-15% of ammonium tungstate based on the mass of ammonium metavanadate is added and mixed to obtain a mixture, the mixture is dried to completion at a temperature of 70-80 DEG C, and then calcined at a temperature of 400-500 DEG C for 2-3h to obtain the V2O5 / TiO2 catalyst.

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