Thallium removal agent composition for water treatment and water treatment method

Abstract

The invention provides a thallium removal agent composition for water treatment and a water treatment method. The thallium removal agent composition comprises a sodium hypochlorite solution, a potassium ferrate solution, an auxiliary agent, a PH regulator, a coagulant and a flocculant. In percentage by mass, the concentration of the sodium hypochlorite solution is 15-30%, and the concentration of the potassium ferrate solution is 8-10%; the auxiliaries comprise copper chloride and inorganic phosphate, and the inorganic phosphate comprises sodium phosphate and / or potassium phosphate. The operation of treating the thallium-containing wastewater by using the thallium-removing agent composition comprises the following steps: regulating the pH value of the wastewater to 10.5-11.5 at normal temperature by using the pH regulator; adding a sodium hypochlorite solution into the wastewater and stirring; adding a potassium ferrate solution and an auxiliary agent into the wastewater, and stirring; adjusting the pH value of the wastewater to 8.5-9.5 at normal temperature by using a pH regulator; and adding a coagulant and a flocculant into the wastewater. After the treatment, the metal thallium in the wastewater can be effectively removed, and ammonia nitrogen, COD (Chemical Oxygen Demand) and other organic pollutants in the water can be synergistically removed.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a thallium removal agent combination for water treatment and a water treatment method. Background Art

[0002] Sintering and desulfurization are inevitable processes in steel production, and sintering wastewater and desulfurization wastewater contain a large number of pollutants, such as heavy metal ions, nitrides, sulfides, etc. Among them, thallium is a typical heavy metal pollutant. If it is directly discharged, it will cause potential harm to the environment and human health. Therefore, the discharge of thallium-containing wastewater in the steel industry needs to be effectively controlled.

[0003] In order to effectively control and direct the thallium pollution in the steel industry wastewater, the government departments of my country have promulgated a series of relevant laws and regulations. For example, the "Industrial Wastewater Thallium Pollutant Emission Standard" (DB43 / 968-2014) issued by Hunan Province stipulates that the emission limit of thallium pollutants in industrial wastewater involving heavy metal thallium is 0.005mg / L; for another example, the "Industrial Wastewater Thallium Pollutant Emission Standard" (DB44 / 1989-2017) issued by Guangdong Province stipulates that the emission limit of total thallium is: 0.005mg / L for existing enterprises and 0.002mg / L for newly built enterprises. / L, the special emission limit is 0.001mg / L; for example, Jiangsu Province has clarified the emission standard DB32 / 3431-2018 for thallium pollutants in steel industry wastewater, which stipulates that the emission limit of thallium pollutants in steel industry wastewater at the wastewater discharge outlet of workshops or production facilities is 0.002mg / L ((direct emission and indirect emission). With the attention paid to thallium pollutants and the further implementation of ultra-low emission standards, in 2020, the Ministry of Ecology and Environment added an emission limit for total thallium in the Amendment to the "Steel Industry Wastewater Discharge Standard" (Draft for Comments), requiring it to be 0.05mg / L.

[0004] The thallium removal process in industrial wastewater mainly adopts the method of adding reagents and coagulation and precipitation. The type of reagents has an impact on the process of water treatment, and the price difference of different reagents is large. In the past, when complex high-salt wastewater was treated for thallium removal, inorganic sulfur reagents such as sodium sulfide were usually used to capture and precipitate thallium. This method has the advantage of low cost. However, sodium sulfide has a peculiar smell, which leads to low work efficiency and high labor cost during manual dosing, and impurities such as suspended matter in wastewater cannot be removed. In addition, when using inorganic sulfur reagents to remove thallium, if slaked lime is used as a pH regulator, there is a problem of excessive mud volume in the entire treatment process. If a liquid pH regulator is used to adjust the pH, there is a problem that the thallium content of the effluent cannot be guaranteed to meet the standard. In this regard, a slaked lime-enhanced sodium sulfide coagulation technology is proposed in the prior art. Although it can ensure a stable thallium removal efficiency, it is difficult to collaboratively remove pollutants such as ammonia nitrogen and COD in the water body. Summary of the invention

[0005] The purpose of the present invention is to provide a thallium removal agent combination for water treatment and a water treatment method, aiming to effectively remove thallium ions in wastewater while also removing pollutants such as ammonia nitrogen and COD, and reducing agent costs.

[0006] To achieve the above object, the present invention provides a thallium removal agent combination for water treatment, comprising: sodium hypochlorite solution, potassium ferrate solution, auxiliary agent, pH regulator, coagulant, and flocculant;

[0007] In terms of mass percentage, the concentration of the sodium hypochlorite solution is 15% to 30%, and the concentration of the potassium ferrate solution is 8% to 10%;

[0008] The auxiliary agent includes copper chloride and inorganic phosphate, and the inorganic phosphate includes sodium phosphate and / or potassium phosphate.

[0009] Optionally, the coagulant is a polyaluminium chloride solution, and the mass percentage of the polyaluminium chloride solution is 30%.

[0010] Optionally, the coagulant is polyferric sulfate.

[0011] Optionally, the flocculant is a polyacrylamide solution, and the mass percentage of the polyacrylamide solution is 1‰ to 3‰.

[0012] Optionally, the pH adjuster includes a first pH adjuster and a second pH adjuster, the first pH adjuster includes an alkaline compound, and the second pH adjuster includes an acidic compound.

[0013] To achieve the above object, the present invention further provides a water treatment method, wherein the water treatment method is performed by the aforementioned thallium removal agent combination for water treatment, and the water treatment method comprises:

[0014] Step S1, using the pH regulator to adjust the pH of the wastewater so that the pH of the wastewater at room temperature is 10.5-11.5;

[0015] Step S2, adding sodium hypochlorite solution to the wastewater treated in step S1 and stirring;

[0016] Step S3, adding potassium ferrate solution and the auxiliary agent to the wastewater treated in step S2 and stirring;

[0017] Step S4, using the pH regulator to adjust the pH of the wastewater treated in step S3 so that the pH of the wastewater at room temperature is 8.5 to 9.5;

[0018] Step S5, adding coagulant and flocculant to the wastewater treated in step S4.

[0019] Optionally, the step S1, the step S2, the step S3, the step S4, and the step S5 are performed in different containers.

[0020] Optionally, the pH of the wastewater adjusted in step S1 at room temperature is 11, and the pH of the wastewater adjusted in step S4 at room temperature is 9.

[0021] Optionally, the stirring speed in step S2 is 300 rpm to 500 rpm, and the reaction time is 15 min to 20 min; the stirring speed in step S3 is 300 rpm to 500 rpm, and the reaction time is 20 min to 25 min.

[0022] Optionally, assuming that the thallium content in the wastewater is 1500 μg / L and the volume of the wastewater is 1 L, the volume of the sodium hypochlorite solution added in step S2 is 20 mL to 40 mL, the volume of the potassium ferrate solution added in step S3 is 8 mL to 14 mL, the mass of copper chloride is 0.2 g to 0.4 g, and the mass of the phosphate in the inorganic phosphate is 0.1 g to 0.2 g.

[0023] Compared with the prior art, the thallium removal agent combination for water treatment and the water treatment method of the present invention have the following advantages:

[0024] The aforementioned thallium removal agent combination for water treatment includes sodium hypochlorite solution, potassium ferrate solution, additives, pH regulator, coagulant, and flocculant; in terms of mass percentage, the concentration of sodium hypochlorite solution is 15% to 30%, and the concentration of potassium ferrate solution is 8% to 10%; the additives include cupric chloride and inorganic phosphates, and the inorganic phosphates include sodium phosphate and / or potassium phosphate. The operation of treating thallium-containing wastewater by using the thallium removal agent combination includes: step S1, using the PH regulator to adjust the PH of the wastewater so that the PH of the wastewater at room temperature is 10.5-11.5; step S2, adding sodium hypochlorite solution to the wastewater treated by step S1 and stirring; step S3, adding potassium ferrate solution and the auxiliary agent to the wastewater treated by step S2 and stirring; step S4, using the PH regulator to adjust the PH of the wastewater treated by step S3 so that the PH of the wastewater at room temperature is 8.5-9.5; step S5, adding coagulant and flocculant to the wastewater treated by step S4. After such treatment, the metal thallium in the wastewater can be effectively removed, and organic pollutants such as ammonia nitrogen and COD in the water can also be synergistically removed. DETAILED DESCRIPTION

[0025] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0026] In addition, each embodiment of the following description has one or more technical features, but this does not mean that the user of the present invention must implement all the technical features in any embodiment at the same time, or can only implement part or all of the technical features in different embodiments separately. In other words, under the premise that implementation is possible, those skilled in the art can selectively implement part or all of the technical features in any embodiment according to the disclosure of the present invention and according to the design specifications or implementation requirements, or selectively implement a combination of part or all of the technical features in multiple embodiments, thereby increasing the flexibility of the implementation of the present invention.

[0027] As used in this specification, the singular forms "a", "an", and "the" include plural objects, and the plural form "a plurality" includes more than two objects, unless the context clearly indicates otherwise. As used in this specification, the term "or" is generally used to include the meaning of "and / or", unless the context clearly indicates otherwise. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] The purpose of the present invention is to provide a double oxidant thallium removal reagent combination for water treatment and a water treatment method, so as to remove pollutants such as ammonia nitrogen and COD while removing thallium, reduce the dosage of the reagent, and save the cost of adding the reagent.

[0029] The thallium removal agent combination for water treatment includes sodium hypochlorite solution, potassium ferrate solution, auxiliary agent, pH regulator, coagulant, and flocculant. The mass percentage of sodium hypochlorite solution is 15% to 30%, and the mass percentage of potassium ferrate solution is 8% to 10%. The auxiliary agent includes copper chloride and inorganic phosphate, and the inorganic phosphate includes sodium phosphate and / or potassium phosphate.

[0030] The sodium phosphate here includes both anhydrous sodium phosphate and hydrated sodium phosphate. Similarly, potassium phosphate includes both anhydrous potassium phosphate and hydrated potassium phosphate.

[0031] The process of treating thallium-containing wastewater using the thallium removal agent combination is as follows, including:

[0032] Step S1, using the pH regulator to adjust the pH of the wastewater so that the pH value of the wastewater at room temperature is 10.5-11.5.

[0033] Step S2, adding an appropriate amount of sodium hypochlorite solution with a mass percentage of 15% to 30% to the wastewater treated in step S1 and stirring.

[0034] Step S3, adding a proper amount of the auxiliary agent and a proper amount of 8% to 10% by mass potassium ferrate solution to the wastewater treated in step S2 and stirring.

[0035] Step S4, using the pH regulator to adjust the pH of the wastewater treated in step S3 so that the pH value of the wastewater at room temperature is 8.5-9.5.

[0036] Step S5, adding the coagulant and the flocculant to the wastewater treated in step S4.

[0037] The priority of reducing substances in wastewater in consuming oxidants is different. Generally speaking, small molecular organic matter in ammonia nitrogen and COD is easier to be oxidized, while large molecular organic matter is more difficult to be oxidized. + It is more difficult to oxidize than ammonia nitrogen and COD.

[0038] In the embodiment of the present invention, potassium ferrate and sodium hypochlorite are used as two oxidants to reduce the amount of potassium ferrate and the cost of adding the agent. By using the auxiliary agent, the effect of reducing Tl + The oxidation difficulty can be reduced to effectively improve the removal effect of metallic thallium.

[0039] Specifically, in step S2, by adding relatively cheap sodium hypochlorite, small molecular organic matter in ammonia nitrogen and COD can first undergo redox reaction with sodium hypochlorite, and compared with directly adding a relatively expensive potassium ferrate solution to make small molecular organic matter in ammonia nitrogen and COD react with potassium ferrate, the dosing cost is relatively low. In step S3, by adding the auxiliary agent, copper chloride and potassium ferrate react synergistically in a phosphoric acid environment to increase Tl + The competitive oxidation of Tl + The difficulty of oxidation makes Tl + Compared with ammonia nitrogen and macromolecular organic matter in COD, it is easier to be oxidized. Therefore, in step S3, even if the oxidant concentration in the wastewater is slightly low, the oxidation of Tl can be achieved. + The oxidation of Tl is carried out to reduce the dosage of potassium ferrate and the cost of adding the reagent. In addition, in the step S3, the oxidant in the wastewater first oxidizes Tl + , and then oxidize the macromolecular organic matter in ammonia nitrogen and COD, so that after executing step S5, the metal thallium in the wastewater can be effectively removed. It can be understood that in Tl +After oxidation is completed, as long as there is enough oxidant in the wastewater, the large molecular organic matter in ammonia nitrogen and COD can also be oxidized and removed.

[0040] It is understandable that after the step S2 is completed, some sodium hypochlorite may still exist in the wastewater. Therefore, the oxidant in the step S3 includes at least potassium ferrate and may also include sodium hypochlorite.

[0041] It should be noted that the normal temperature refers to 20°C to 30°C. The reason why the mass percentage of the sodium hypochlorite solution used in the embodiment of the present invention is within the range of 15% to 30% is that the mass percentage of the sodium hypochlorite solution higher than 30% is likely to cause safety accidents, and the mass percentage of the sodium hypochlorite solution lower than 15% is not good in oxidation effect. The mass percentage of potassium ferrate is within the range of 8% to 10% because, on the one hand, the dissolution rate of potassium ferrate is considered, and on the other hand, the oxidation effect of potassium ferrate is considered.

[0042] It should also be noted that the amounts of various agents added in step S2 and step S3 should be appropriate. For the sodium hypochlorite solution added in step S2, if the amount added is too much, it will cause waste, and if the amount added is too little, it will not be able to fully oxidize the small molecular organic matter in ammonia nitrogen and COD. For the potassium ferrate solution added in step S3, if the amount added is too much, it will cause waste, and if the amount added is too little, it will not be able to fully oxidize Tl + When the amount of inorganic phosphate added is sufficient, if the amount of copper chloride added is too much, it will cause waste, and if it is too little, the synergistic effect between it and potassium ferrate is not enough to effectively reduce Tl + The difficulty of oxidation; if too much phosphate is added, it will not only cause waste, but also cause the phosphorus content of the treated wastewater to exceed the standard and fail to meet the discharge standard. If too little phosphate is added, it will not provide an effective phosphoric acid environment and the copper chloride and potassium ferrate will not be able to produce a synergistic effect.

[0043] In practice, assuming that the thallium content in the wastewater is 1500 μg / L and the volume of the wastewater is 1 L, the volume of the sodium hypochlorite solution added in step S2 is 20 mL to 40 mL, the volume of the potassium ferrate solution added in step S3 is 8 mL to 14 mL, the mass of copper chloride is 0.2 g to 0.4 g, and the mass of the phosphate in the inorganic phosphate is 0.1 g to 0.2 g. It can be understood that if the inorganic phosphate is all anhydrous sodium phosphate, then when treating 1L of wastewater containing 1500μg / L of thallium, the amount of anhydrous sodium phosphate added in step S3 is 0.17g~0.35g; if the inorganic phosphate is all anhydrous potassium phosphate, then when treating 1L of wastewater containing 1500μg / L of thallium, the amount of anhydrous potassium phosphate added in step S3 is 0.22g~0.45g.

[0044] Preferably, the inorganic phosphate is all sodium phosphate dodecahydrate, which has the advantage of low price. When treating 1L of wastewater containing 1500μg / L of thallium, the mass of sodium phosphate dodecahydrate required is 0.4g to 0.8g.

[0045] In addition, in an optional operation, copper chloride is preliminarily dissolved in water to form a solution, which is then added to the wastewater, and inorganic phosphate is preliminarily dissolved in water to form a solution, which is then added to the wastewater.

[0046] Optionally, the pH regulator includes a first pH regulator and a second pH regulator, wherein the first pH regulator includes an alkaline compound and the second pH regulator includes an acidic compound. More specifically, the first pH regulator includes but is not limited to at least one of slaked lime and sodium hydroxide, and the second pH regulator includes but is not limited to a hydrochloric acid solution. Thus, a suitable pH regulator can be selected as needed to adjust the acidity and alkalinity of the wastewater.

[0047] Alternatively, the coagulant may be a conventional coagulant, such as a polyaluminium chloride solution. Alternatively, the coagulant may also be polyferric sulfate.

[0048] Optionally, the flocculant may be a conventional flocculant, such as a polyacrylamide solution.

[0049] Furthermore, an embodiment of the present invention also provides a water treatment method, comprising steps S1 to S5 as described above.

[0050] It can be understood that the step S1 uses the first pH regulator to adjust the pH of the wastewater, and preferably adjusts the pH of the wastewater to 11 at room temperature. The step S4 uses the second pH regulator to adjust the pH of the wastewater, and preferably adjusts the pH of the wastewater to 9 at room temperature.

[0051] Further, each step in the water treatment process is performed in a different container. Specifically in the embodiment of the present invention, step S1 is performed in a regulating tank, step S2 is performed in a first reaction tank, step S3 is performed in a second reaction tank, step S4 is performed in an equalizing tank, and step S5 is performed in an inclined plate sedimentation tank.

[0052] In the step S2, the wastewater stays in the first reaction tank for 15 to 20 minutes, and the wastewater in the first reaction tank is preferably stirred by a first mechanical stirring device at a stirring speed of 300 to 500 rpm. In the step S3, the wastewater stays in the second reaction tank for 20 to 25 minutes, and the wastewater in the second reaction tank is preferably stirred by a second mechanical stirring device at a stirring speed of 300 to 500 rpm.

[0053] In step S5, the coagulant and the flocculant are added in conventional amounts. In addition, when polyaluminium chloride solution is used as the coagulant, the mass percentage of the polyaluminium chloride solution can be 30%. The mass percentage of the polyacrylamide solution used as the flocculant can be 1‰ to 3‰.

[0054] In order to make the objects, advantages and features of the present invention more clear, the present invention is further described in detail below in conjunction with specific embodiments.

[0055] <Example 1>

[0056] The treatment object is the desulfurization wastewater of a power plant, which produces 9t / d of water per day. The pH of the desulfurization wastewater at room temperature is about 5.7, the thallium content is about 480μg / L, and the ammonia nitrogen content is about 75mg / L.

[0057] The Environmental Protection Bureau where the power plant is located requires that the thallium content in the power plant's workshop drainage outlet be controlled to keep the thallium content in the effluent below 5μg / L and the ammonia nitrogen content below 50mg / L.

[0058] The wastewater treatment process is:

[0059] Step S1, allowing the wastewater to enter the regulating tank, and using sodium hydroxide to adjust the pH of the wastewater to about 11 at room temperature.

[0060] Step S2: the wastewater treated in step S1 is heated to 1.5 m 3 / h flow into the first reaction tank, and at a rate of 0.019m 3 / h flow rate of 15% sodium hypochlorite solution by mass is added to the first reaction tank, and the first mechanical stirring device is operated at a speed of 300rpm for stirring. In this step, the residence time of the wastewater in the first reaction tank is 20min, that is, the reaction time of this step is about 20min.

[0061] Step S3: subjecting the wastewater treated in step S2 to a temperature of 1.5 m 3 / h flow into the second reaction tank, and at a rate of 0.003m 3 / h flow rate to the second reaction tank to add 3% by mass sodium phosphate solution, according to 0.004m 3 / h flow rate to the second reaction tank to add 4% by mass copper chloride solution, and at a rate of 0.004m 3 / h flow rate to add 9% by mass potassium ferrate solution to the second reaction pool, and at the same time, the second mechanical stirring device stirs at a speed of 350rpm. In this step, the residence time of the wastewater in the second reaction pool is 20min, that is, the reaction time of this step is about 20min. In addition, in this step, the operator adds sodium phosphate solution and copper chloride solution to the second reaction pool at one end of the second reaction pool, and adds potassium ferrate solution to the second reaction pool at the middle end of the second reaction pool.

[0062] Step S4: subjecting the wastewater treated in step S3 to a temperature of 1.5 m 3 / h flow rate into the equalization tank, and hydrochloric acid is used to adjust the pH of the wastewater to 9 at room temperature.

[0063] Step S5: subjecting the wastewater treated in step S4 to a temperature of 1.5 m 3 / h flow rate into the inclined plate sedimentation tank, and add 30% by mass percent polyaluminium chloride solution and 2‰ by mass percent polyacrylamide solution into the wastewater for coagulation and sedimentation.

[0064] After the above treatment, the thallium content in the effluent of the power plant stabilized at around 3μg / L, and the ammonia nitrogen content dropped to around 45mg / L, which met the local environmental protection requirements.

[0065] <Example 2>

[0066] The treatment object is the sintering wastewater of a steel plant, which produces 19t / d of water per day. The pH of the sintering wastewater at room temperature is about 1.2, the thallium content is about 3363μg / L, and the COD content is about 230mg / L~285mg / L.

[0067] The Environmental Protection Bureau in the area where the steel plant is located requires that the thallium content in the workshop drainage outlet be controlled so that the thallium content in the effluent is below 5μg / L and the COD content is below 200mg / L.

[0068] The wastewater treatment process is:

[0069] Step S1, allowing the wastewater to enter the regulating tank, and using sodium hydroxide to adjust the pH of the wastewater to about 11.5 at room temperature.

[0070] Step S2: the wastewater treated in step S1 is heated to 3.5 m 3 / h flow into the first reaction tank, and at a rate of 0.175m 3 / h flow rate of adding 30% sodium hypochlorite solution by mass to the first reaction tank, while the first mechanical stirring device is operated at a speed of 500rpm for stirring. In this step, the residence time of the wastewater in the first reaction tank is 15min, that is, the reaction time of this step is about 15min.

[0071] Step S3: the wastewater treated in step S2 is heated to 3.5 m 3 / h flow into the second reaction tank, and at a rate of 0.1m 3 / h flow rate to the second reaction tank to add 3% by mass potassium phosphate solution, according to 0.044m 3 / h flow rate to the second reaction tank to add 5% by mass copper chloride solution, and at a rate of 0.1m 3 / h flow rate to add 8% by mass potassium ferrate solution to the second reaction pool, and at the same time, the second mechanical stirring device stirs at a speed of 300rpm. In this step, the residence time of the wastewater in the second reaction pool is 25min, that is, the reaction time of this step is about 25min. In addition, in this step, the operator adds sodium phosphate solution and copper chloride solution to the second reaction pool at one end of the second reaction pool, and adds potassium ferrate solution to the second reaction pool at the middle end of the second reaction pool.

[0072] Step S4: the wastewater treated in step S3 is heated to 3.5 m 3 / h flow rate into the equalization tank, and hydrochloric acid is used to adjust the pH of the wastewater to 8.5 at room temperature.

[0073] Step S5: the wastewater treated in step S4 is heated to 3.5 m 3 / h flow rate into the inclined plate sedimentation tank, and add 30% by mass percent polyaluminium chloride solution and 1‰ by mass percent polyacrylamide solution into the wastewater for coagulation and sedimentation.

[0074] After the above treatment, the PH value of the effluent from the steel plant at room temperature fluctuates within the range of 9-10, the thallium content is stable within the range of 2.5μg / L~3.2μg / L, and the average COD content is 180mg / L~195mg / L, which meets the local environmental protection requirements.

[0075] <Example 3>

[0076] The treatment object is the sintering wastewater of a steel plant, the daily water output of which is 42t / d. The pH of the sintering wastewater at room temperature is about 2.7, the thallium content is about 4369μg / L, the ammonia nitrogen content is about 56mg / L, and the COD content is 110mg / L~130mg / L.

[0077] The Environmental Protection Bureau where the power plant is located requires that the thallium content in the power plant's workshop drainage outlet be controlled so that the thallium content in the effluent is below 2μg / L, the ammonia nitrogen content is below 50mg / L, and the COD content is below 100mg / L.

[0078] The wastewater treatment process is:

[0079] Step S1, allowing the wastewater to enter the regulating tank, and using sodium hydroxide to adjust the pH of the wastewater to 10.5 at room temperature.

[0080] Step S2: subjecting the wastewater treated in step S1 to a temperature of 5 m 3 / h flow into the first reaction tank, and at a rate of 0.5m 3 / h flow rate of adding 20% ​​sodium hypochlorite solution by mass to the first reaction tank, while the first mechanical stirring device is operated at a speed of 400rpm for stirring. In this step, the residence time of the wastewater in the first reaction tank is 20min, that is, the reaction time of this step is about 20min.

[0081] Step S3: subjecting the wastewater treated in step S2 to a temperature of 5 m 3 / h flow into the second reaction tank, and at a rate of 0.15m 3 / h flow rate to the second reaction tank to add 3% by mass sodium phosphate solution, according to 0.1m 3 / h flow rate to the second reaction tank to add 5% by mass copper chloride solution, and at a rate of 0.18m 3 / h flow rate to add 10% by mass potassium ferrate solution to the second reaction pool, and at the same time, the second mechanical stirring device stirs at a speed of 500rpm. In this step, the residence time of the wastewater in the second reaction pool is 25min, that is, the reaction time of this step is about 25min. In addition, in this step, the operator adds sodium phosphate solution and copper chloride solution to the second reaction pool at one end of the second reaction pool, and adds potassium ferrate solution to the second reaction pool at the middle end of the second reaction pool.

[0082] Step S4: subjecting the wastewater treated in step S3 to a temperature of 5 m 3 / h flow rate into the equalization tank, and hydrochloric acid is used to adjust the pH of the wastewater to 9.5 at room temperature.

[0083] Step S5: subjecting the wastewater treated in step S4 to a temperature of 5 m 3 / h flow rate into the inclined plate sedimentation tank, and add 30% by mass percent polyaluminium chloride solution and 3‰ by mass percent polyacrylamide solution into the wastewater for coagulation and sedimentation.

[0084] After the above treatment, the PH value of the effluent from the steel plant at room temperature is maintained between 9 and 10, the thallium content is stabilized at 1.1μg / L~1.5μg / L, the ammonia nitrogen content is stabilized at around 38mg / L~45mg / L, and the average COD content is 90mg / L, which meets local environmental protection requirements.

[0085] Although the present invention is disclosed as above, it is not limited thereto. Those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A thallium removal agent combination for water treatment, characterized in that: include: Sodium hypochlorite solution, potassium ferrate solution, additives, pH regulator, coagulant, and flocculant; In terms of mass percentage, the concentration of the sodium hypochlorite solution is 15% to 30%, and the concentration of the potassium ferrate solution is 8% to 10%; The auxiliary agent includes copper chloride and inorganic phosphate, and the inorganic phosphate includes sodium phosphate and / or potassium phosphate.

2. The thallium removal agent combination for water treatment according to claim 1, characterized in that: The coagulant is a polyaluminium chloride solution, and the mass percentage of the polyaluminium chloride solution is 30%.

3. The thallium removal agent combination for water treatment according to claim 1, characterized in that: The coagulant is polyferric sulfate.

4. The thallium removal agent combination for water treatment according to claim 1, characterized in that: The flocculant is a polyacrylamide solution, and the mass percentage of the polyacrylamide solution is 1‰ to 3‰.

5. The thallium removal agent combination for water treatment according to claim 1, characterized in that: The pH adjuster includes a first pH adjuster and a second pH adjuster, wherein the first pH adjuster includes an alkaline compound and the second pH adjuster includes an acidic compound.

6. A water treatment method, characterized in that: The water treatment method is performed based on the thallium removal agent combination for water treatment according to any one of claims 1 to 5, and the water treatment method comprises: Step S1, using the pH regulator to adjust the pH of the wastewater so that the pH of the wastewater at room temperature is 10.5-11.5; Step S2, adding sodium hypochlorite solution to the wastewater treated in step S1 and stirring; Step S3, adding potassium ferrate solution and the auxiliary agent to the wastewater treated in step S2 and stirring; Step S4, using the pH regulator to adjust the pH of the wastewater treated in step S3 so that the pH of the wastewater at room temperature is 8.5 to 9.5; Step S5, adding coagulant and flocculant to the wastewater treated in step S4.

7. The water treatment method according to claim 6, characterized in that: The step S1, the step S2, the step S3, the step S4 and the step S5 are performed in different containers.

8. The water treatment method according to claim 6 or 7, characterized in that: The pH of the wastewater adjusted in step S1 at room temperature is 11, and the pH of the wastewater adjusted in step S4 at room temperature is 9.

9. The water treatment method according to claim 6, characterized in that: The stirring speed in step S2 is 300 rpm to 500 rpm, and the reaction time is 15 min to 20 min; the stirring speed in step S3 is 300 rpm to 500 rpm, and the reaction time is 20 min to 25 min.

10. The water treatment method according to claim 6, characterized in that: Assuming that the thallium content in the wastewater is 1500 μg / L and the volume of the wastewater is 1 L, the volume of the sodium hypochlorite solution added in step S2 is 20 mL to 40 mL, the volume of the potassium ferrate solution added in step S3 is 8 mL to 14 mL, the mass of copper chloride is 0.2 g to 0.4 g, and the mass of the phosphate in the inorganic phosphate is 0.1 g to 0.2 g.