Preparation method and process of a water purifying agent polyaluminum chloride solution

Abstract

The application discloses a preparation method and process of a water purifying agent polyaluminum chloride solution, and contains components: aluminum hydroxide, calcium carbonate, dilute hydrochloric acid solution and sodium hydroxide solution, and relates to the technical field of water purifying agents. The preparation method and process of the water purifying agent polyaluminum chloride solution determine the purification treatment degree of the water purifying agent polyaluminum chloride solution on waste water and sewage by using the color brightness change of a synthetic pigment after being dissolved in water, and then facilitate the determination of the water purifying agent adding amount; meanwhile, the accurate feeding of the water purifying agent when sewage with different pollution degrees is treated is solved, the problem that the water purifying agent is added in a small amount and leads to incomplete sewage treatment is avoided, the problem that the water purifying agent is added in an excessive amount and leads to secondary pollution of the sewage is avoided; and the unreacted polyaluminum chloride solution is dispersed at a high speed in the waste water, the impurities in the waste water are dissolved and polymerized, and thus the flocculation efficiency of the water purifying agent on the impurities is improved.

Description

Technical Field

[0001] This invention relates to the field of water purification agent technology, specifically to a method and process for preparing a polyaluminum chloride solution for water purification. Background Technology

[0002] Polyaluminum chloride and its composite water purification agents have a wide range of applications and occupy an important position in urban water supply and wastewater treatment. High-efficiency water purification agents are indispensable pretreatment processes in urban surface water purification, industrial wastewater treatment (such as in stone processing, chemical, power, coal washing, printing and dyeing, leather making, pharmaceutical, papermaking, and metallurgical industries), and especially in the deep treatment and reuse of industrial and urban sewage. They can significantly remove various suspended solids in water, with a removal rate of 80-95% or more.

[0003] Patent CN109678232A discloses a novel polyaluminum chloride water purifier and its preparation method. The novel polyaluminum chloride water purifier has an alumina content of 10-12 wt%, a basicity of 70-95 wt%, a water-insoluble content of ≤0.1 wt%, and a pH (10 g / L aqueous solution) value of 4.5-5.0. Compared with traditional production processes, the process technology uses high-speed dispersion and homogenization technology instead of conventional stirring technology, solving the defect of limited polymerization degree adjustment in conventional alkali conditioning processes.

[0004] However, polyaluminum chloride (PAC) still has drawbacks such as slow flocculation speed, poor flocculation effect, and high production cost. Therefore, this study aims to address these problems by providing a method and process for preparing PAC solution for water purification agents, thereby resolving the issues of slow flocculation speed and poor flocculation effect currently found in water purification agents. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method and process for preparing polyaluminum chloride solution as a water purification agent, which solves the problems of slow flocculation speed and poor flocculation effect in current water purification agents.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method and process for preparing a polyaluminum chloride solution for water purification, comprising the following steps:

[0007] Step 1: Select aluminum hydroxide, calcium carbonate, dilute hydrochloric acid solution, and sodium hydroxide solution;

[0008] The second step is to add a measured amount of aluminum hydroxide into the reaction tank, and then pump a measured amount of dilute hydrochloric acid solution into the reaction tank. Subsequently, the reaction is carried out by heating with steam to obtain aluminum chloride and water.

[0009] The third step is to add a certain amount of calcium carbonate and then continue the reaction at a specified temperature. After the reaction is completed, the liquid in the reaction tank is precipitated and the supernatant obtained from the precipitation is used as the mother liquor of polyaluminum chloride.

[0010] The fourth step is to use sodium hydroxide solution as the sub-solution for polyaluminum chloride;

[0011] The fifth step is to mix the polyaluminum chloride mother liquor and the polyaluminum chloride daughter liquor to make a polyaluminum chloride solution for water purification.

[0012] The sixth step involves adding a measured amount of synthetic pigment to the supernatant and mixing it thoroughly to obtain a polyaluminum chloride solution sample.

[0013] Preferably, in the second step, the molar ratio of aluminum hydroxide to dilute hydrochloric acid solution is 1:3;

[0014] In the third step, the molar ratio of calcium carbonate to aluminum hydroxide plus dilute hydrochloric acid solution is 1:4.

[0015] Preferably, the reaction equation in the second step is: Al(OH)3 + 3HCl = AlCl3 + 3H2O.

[0016] A process for preparing a polyaluminum chloride solution for water purification is disclosed. This process utilizes the polyaluminum chloride solution and a sample obtained by the aforementioned method for preparing a polyaluminum chloride solution for water purification. The process includes the following steps:

[0017] Step 1: First, obtain the color brightness of the polyaluminum chloride solution sample, and establish a brightness color card based on this color brightness. The brightness color card contains several brightness ranges, and a purification ratio is set for each brightness range.

[0018] Among them, the purification ratio corresponding to the brightness range is a preset value obtained based on experimental data;

[0019] Step 2: First, weigh A0 mass of polyaluminum chloride solution sample, and at the same time select B0 volume of wastewater.

[0020] Where A0 and B0 represent the mass value of the polyaluminum chloride solution sample and the volume value of the wastewater, respectively;

[0021] Step 3: Next, add A0 mass of polyaluminum chloride solution sample to B0 volume of wastewater to obtain wastewater treatment sample;

[0022] Step 4: After letting the wastewater treatment sample stand for a certain period of time, obtain the color brightness of the wastewater treatment sample and mark it as the sample brightness.

[0023] The sample brightness was then matched with the brightness color chart. Based on the matching results, the corresponding brightness range in the brightness color chart was determined, and then the preset purification ratio corresponding to that brightness range was obtained.

[0024] Step 5, then obtain the total wastewater volume B. z ;

[0025] Next, according to the formula: The mass A of polyaluminum chloride mother liquor used to obtain a certain amount of wastewater z ;

[0026] Step six, then based on the preset mass ratio u1:u2 of the polyaluminum chloride mother liquor and the polyaluminum chloride daughter liquor, and in conjunction with the formula... Determine the mass Y of polyaluminum chloride solution used for a given wastewater volume. z ;

[0027] The preferred method for obtaining the purification ratio corresponding to the brightness range is as follows:

[0028] The results were obtained through experimental testing of polyaluminum chloride solution samples, and the experimental testing methods are as follows:

[0029] First, the same type of wastewater was selected as the wastewater sample, and then multiple sets of wastewater samples with different water levels were placed in multiple glass containers.

[0030] Subsequently, the same mass of polyaluminum chloride solution samples were added to glassware at different wastewater levels;

[0031] After a specified time, the color brightness of the wastewater in each glass container was obtained after reacting the polyaluminum chloride solution sample with wastewater samples at different water levels.

[0032] Then, the impurities generated by the reaction of polyaluminum chloride solution samples with wastewater in each glassware were filtered out. Next, the wastewater quality in each glassware was tested by a wastewater analyzer to obtain the corresponding quality parameters. At the same time, the corresponding quality parameters of the wastewater samples were also obtained.

[0033] Then, the corresponding mass parameters of the wastewater in each glass container were calculated with the corresponding mass parameters of the wastewater sample to obtain the corresponding purification ratio L;

[0034] Preferably, the calculation method is to obtain it by the formula L=Cq / (Cy-C0), where Cq represents the corresponding mass parameter of wastewater in each glassware, Cy represents the corresponding mass parameter of wastewater sample, and C0 is a preset value, which represents the mass parameter corresponding to the wastewater treatment discharge standard.

[0035] A purification process for a polyaluminum chloride (PAC) solution used as a water purifier is disclosed. This process achieves the required quality of PAC solution for a given volume of wastewater through a method for preparing the PAC solution described above, and a process for adjusting the PAC solution. The process includes the following steps:

[0036] S1. First, put the specified amount of polyaluminum chloride mother liquor into a certain amount of wastewater;

[0037] S2. Next, the polyaluminum chloride mother liquor reacts with the wastewater to obtain aluminum hydroxide and a small amount of dilute hydrochloric acid solution, making the wastewater acidic.

[0038] S3. Simultaneously, calcium carbonate reacts with a small amount of dilute hydrochloric acid solution to produce carbon dioxide gas and calcium ions.

[0039] S4. Subsequently, the polyaluminum chloride solution is added to the wastewater;

[0040] S5. Next, the polyaluminum chloride solution reacts with the aluminum hydroxide obtained in step S2 to generate sodium aluminate.

[0041] S6. Then sodium aluminate reacts with the calcium ions obtained in step S3 to generate calcium aluminate and precipitate.

[0042] Preferably, the ionic reaction in step S2 is as follows:

[0043] Preferably, the ionic reaction equation in step S3 is: CaCO3 + 2H+ + =CO2↑ + H2O + Ca 2+ ;

[0044] Preferably, the carbon dioxide gas obtained in step S3 is used to assist the diffusion of unreacted polyaluminum chloride mother liquor and polyaluminum chloride daughter liquor in the wastewater.

[0045] This invention provides a method and process for preparing polyaluminum chloride solution as a water purification agent. Compared with the prior art, it has the following advantages:

[0046] This invention adds a fixed amount of synthetic pigment, so that when the polyaluminum chloride solution is used as a water purifier, the color brightness change after the synthetic pigment dissolves in water can be used to determine the degree of purification treatment of wastewater by the polyaluminum chloride solution, thus facilitating the determination of the amount of water purifier to be added.

[0047] This invention separates and stores the prepared polyaluminum chloride mother liquor and polyaluminum chloride daughter liquor, and then adds them one by one to mix them before use, thereby increasing the shelf life of the polyaluminum chloride solution for water purification and improving the flocculation efficiency of the polyaluminum chloride solution for impurities.

[0048] This invention analyzes the mass of polyaluminum chloride mother liquor added to a certain amount of wastewater by using a polyaluminum chloride solution sample. Simultaneously, based on a preset mass ratio of polyaluminum chloride mother liquor to polyaluminum chloride sub-liquid, it determines the mass of polyaluminum chloride sub-liquid used for a certain amount of wastewater. This allows users to accurately and effectively determine the amount of polyaluminum chloride solution used in wastewater treatment, solving the problem of precise dosing of water purification agents when treating wastewater with different levels of pollution. It avoids the problem of incomplete wastewater treatment due to insufficient addition of water purification agents, and also avoids secondary pollution of wastewater due to excessive addition of water purification agents.

[0049] This invention utilizes the reaction of calcium carbonate with a small amount of dilute hydrochloric acid solution to generate carbon dioxide gas. Since the gas is insoluble in water and produces bubbles, the unreacted polyaluminum chloride mother liquor and polyaluminum chloride daughter liquor are rapidly dispersed in the wastewater, thereby dissolving and polymerizing impurities in the wastewater and improving the coagulation effect of the water purification agent. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0051] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] As an embodiment of the present invention

[0053] Please see Figure 1 The present invention provides a technical solution: a method for preparing a polyaluminum chloride solution for water purification includes the following steps:

[0054] Step 1: Select aluminum hydroxide, calcium carbonate, dilute hydrochloric acid solution, and sodium hydroxide solution;

[0055] The second step is to add a measured amount of aluminum hydroxide into the reaction tank, and then pump a measured amount of dilute hydrochloric acid solution into the reaction tank. The molar ratio of aluminum hydroxide to dilute hydrochloric acid solution is 1:3. Then, the reaction is carried out by heating with steam, and the reaction equation is: Al(OH)3 + 3HCl = AlCl3 + 3H2O, to obtain aluminum chloride and water.

[0056] The third step is to add a certain amount of calcium carbonate, wherein the molar ratio of calcium carbonate to aluminum hydroxide plus dilute hydrochloric acid solution is 1:4. Then, the reaction continues at a specified temperature. After the reaction is completed, the liquid in the reaction tank is precipitated, and the supernatant obtained from the precipitation is used as the mother liquor of polyaluminum chloride.

[0057] The fourth step is to use sodium hydroxide solution as the sub-solution for polyaluminum chloride;

[0058] The fifth step is to mix the polyaluminum chloride mother liquor and the polyaluminum chloride daughter liquor to make a polyaluminum chloride solution for water purification.

[0059] The sixth step involves adding a measured amount of synthetic pigment to the supernatant and mixing it thoroughly to obtain a polyaluminum chloride solution sample.

[0060] This invention adds a fixed amount of synthetic pigment, so that when the polyaluminum chloride solution is used as a water purifier, the color brightness change after the synthetic pigment dissolves in water can be used to determine the degree of purification treatment of wastewater by the polyaluminum chloride solution, thus facilitating the determination of the amount of water purifier to be added.

[0061] In this embodiment, the prepared polyaluminum chloride mother liquor and polyaluminum chloride daughter liquor are stored separately and then added back in batches for use, thereby increasing the shelf life of the polyaluminum chloride solution and improving the flocculation efficiency of the polyaluminum chloride solution for impurities.

[0062] As an embodiment two of the present invention

[0063] This invention provides a technical solution: a process for preparing a polyaluminum chloride solution for water purification. This process is achieved using a polyaluminum chloride solution and a polyaluminum chloride solution sample obtained by the method described in Example 1. The process includes the following steps:

[0064] Step 1: First, obtain the color brightness of the polyaluminum chloride solution sample, and establish a brightness color card based on this color brightness. The brightness color card contains several brightness ranges, and a purification ratio is set for each brightness range.

[0065] The purification ratio corresponding to each brightness range is a preset value obtained based on experimental data. The purification ratio corresponding to each brightness range is obtained by experimentally testing polyaluminum chloride solution samples. The experimental testing method is as follows:

[0066] First, the same type of wastewater was selected as the wastewater sample, and then multiple sets of wastewater samples with different water levels were placed in multiple glass containers.

[0067] Subsequently, the same mass of polyaluminum chloride solution samples were added to glassware at different wastewater levels;

[0068] After a specified time, the color brightness of the wastewater in each glass container was obtained after reacting the polyaluminum chloride solution sample with wastewater samples at different water levels.

[0069] Then, the impurities generated by the reaction of polyaluminum chloride solution samples with wastewater in each glassware were filtered out. Next, the wastewater quality in each glassware was tested by a wastewater analyzer to obtain the corresponding quality parameters. At the same time, the corresponding quality parameters of the wastewater samples were also obtained.

[0070] Then, the corresponding mass parameters of the wastewater in each glass container were calculated with the corresponding mass parameters of the wastewater sample to obtain the corresponding purification ratio L;

[0071] The purification ratio L is calculated using the formula L=Cq / (Cy-C0), where Cq represents the corresponding mass parameter of the wastewater in each glass container, Cy represents the corresponding mass parameter of the wastewater sample, and C0 is a preset value, which represents the mass parameter corresponding to the wastewater treatment discharge standard.

[0072] Step 2: First, weigh A0 mass of polyaluminum chloride solution sample, and at the same time select B0 volume of wastewater.

[0073] Where A0 and B0 represent the mass value of the polyaluminum chloride solution sample and the volume value of the wastewater, respectively;

[0074] Step 3: Next, add A0 mass of polyaluminum chloride solution sample to B0 volume of wastewater to obtain wastewater treatment sample;

[0075] Step 4: After letting the wastewater treatment sample stand for a certain period of time, obtain the color brightness of the wastewater treatment sample and mark it as the sample brightness.

[0076] The sample brightness was then matched with the brightness color chart. Based on the matching results, the corresponding brightness range in the brightness color chart was determined, and then the preset purification ratio corresponding to that brightness range was obtained.

[0077] Step 5, then obtain the total wastewater volume B. z ;

[0078] Next, according to the formula: The mass A of polyaluminum chloride mother liquor used to obtain a certain amount of wastewater z ;

[0079] Step six, then based on the preset mass ratio u1:u2 of the polyaluminum chloride mother liquor and the polyaluminum chloride daughter liquor, and in conjunction with the formula... Determine the mass Y of polyaluminum chloride solution used for a given wastewater volume. z ;

[0080] This invention analyzes the mass of polyaluminum chloride mother liquor added to a certain amount of wastewater by using a polyaluminum chloride solution sample. Simultaneously, based on a preset mass ratio of polyaluminum chloride mother liquor to polyaluminum chloride sub-liquid, it determines the mass of polyaluminum chloride sub-liquid used for a certain amount of wastewater. This allows users to accurately and effectively determine the amount of polyaluminum chloride solution used in wastewater treatment, solving the problem of precise dosing of water purification agents when treating wastewater with different levels of pollution. It avoids the problem of incomplete wastewater treatment due to insufficient addition of water purification agents, and also avoids secondary pollution of wastewater due to excessive addition of water purification agents.

[0081] As an embodiment three of the present invention

[0082] This invention provides a technical solution: a purification process for a polyaluminum chloride (PAC) solution used as a water purifier. This process achieves the required quality of PAC solution for a given volume of wastewater by using a PAC solution prepared by a method described in Example 1 and a PAC solution preparation process described in Example 2. The process includes the following steps:

[0083] S1. First, put the specified amount of polyaluminum chloride mother liquor into a certain amount of wastewater;

[0084] S2. Next, the polyaluminum chloride mother liquor reacts with the wastewater, and the ionic reaction mechanism is as follows: Aluminum hydroxide and a small amount of dilute hydrochloric acid solution are obtained, making the wastewater acidic;

[0085] S3. Simultaneously, calcium carbonate reacts with a small amount of dilute hydrochloric acid solution. The ionic equation for this reaction is: CaCO3 + 2H+ + =CO2↑ + H2O + Ca 2+ It generates carbon dioxide gas and calcium ions;

[0086] Carbon dioxide gas is used to assist the diffusion of unreacted polyaluminum chloride mother liquor and polyaluminum chloride daughter liquor in the wastewater;

[0087] S4. Subsequently, the polyaluminum chloride solution is added to the wastewater;

[0088] S5. Next, the polyaluminum chloride solution reacts with the aluminum hydroxide obtained in step S2 to generate sodium aluminate.

[0089] S6. Then sodium aluminate reacts with the calcium ions obtained in step S3 to generate calcium aluminate and precipitate.

[0090] This invention utilizes the reaction of calcium carbonate with a small amount of dilute hydrochloric acid solution to generate carbon dioxide gas. Since the gas is insoluble in water and produces bubbles, the unreacted polyaluminum chloride mother liquor and polyaluminum chloride daughter liquor are rapidly dispersed in the wastewater, thereby dissolving and polymerizing impurities in the wastewater and improving the coagulation effect of the water purification agent.

[0091] Furthermore, any content not described in detail in this specification is existing technology known to those skilled in the art.

[0092] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A process for the preparation of a polyaluminum chloride solution as a water purifying agent, characterized in that, The process is achieved by polymerization of aluminum chloride solution and polymerization of aluminum chloride solution sample, the preparation method of the polymerization of aluminum chloride solution comprises the following steps: First, select aluminum hydroxide, calcium carbonate, dilute hydrochloric acid solution and sodium hydroxide solution; Second, put a certain amount of aluminum hydroxide into the reaction tank, then pump a certain amount of dilute hydrochloric acid solution into the reaction tank, and then react by steam heating to obtain aluminum chloride and water; Third, add a certain amount of calcium carbonate, then continue to react at a specified temperature, and after the reaction is completed, the liquid in the reaction tank is precipitated, and the supernatant obtained by precipitation is used as the mother liquor of polymerized aluminum chloride; Fourth, the sodium hydroxide solution is used as the sub-liquid of the polymerized aluminum chloride; Fifth, the mother liquor and the sub-liquid of the polymerized aluminum chloride are mixed to obtain the polymerized aluminum chloride solution for water purification; Then add a certain amount of synthetic pigment to the supernatant and mix evenly to obtain the polymerized aluminum chloride solution sample; The method for determining the amount of polymerized aluminum chloride solution in the water purification process by polymerized aluminum chloride solution and polymerized aluminum chloride solution sample comprises the following steps: Step one, first obtain the color brightness of the polymerized aluminum chloride solution sample, and establish a brightness color card based on the color brightness, the brightness color card contains several brightness intervals, and a purification ratio is set for each brightness interval; Wherein, the purification ratio corresponding to the brightness interval is a preset value obtained according to experimental data; Step two, first weigh A0 mass of polymerized aluminum chloride solution sample, and select B0 volume of wastewater at the same time; Wherein, A0 and B0 represent the mass value of the polymerized aluminum chloride solution sample and the volume value of the wastewater respectively; Step three, then add A0 mass of polymerized aluminum chloride solution sample to B0 volume of wastewater to obtain wastewater treatment sample; Step four, after the wastewater treatment sample is placed for a certain time, the color brightness of the wastewater treatment sample is obtained and marked as sample brightness; Then match the sample brightness with the brightness color card, determine the corresponding brightness interval in the brightness color card according to the matching result, then obtain the purification ratio corresponding to the brightness interval, and mark the purification ratio as L; Step five, the total amount of wastewater B is then obtained z ; Then according to the formula: , the mass A of the polyaluminum chloride mother liquor used for a certain amount of wastewater is obtained z ; Step six, then according to the predetermined mass ratio u1:u2 of the polyaluminum chloride mother liquor and the polyaluminum chloride sub-liquor, and combining the formula , the mass Y of the polyaluminum chloride sub-liquor used for a certain amount of wastewater is determined z ; The way to obtain the purification ratio L corresponding to the brightness interval is: Through experimental test of the polymerized aluminum chloride solution sample, the experimental test method is as follows: First, select the same kind of wastewater as the wastewater sample, then pour the wastewater sample with different water levels into multiple glass containers; Then add the same mass of polymerized aluminum chloride solution sample to the glass containers with different water levels; After the polymerized aluminum chloride solution sample reacts with the wastewater sample with different water levels for a specified time, the color brightness of the wastewater in each glass container is obtained; Then filter out the impurities generated by the reaction of the polymerized aluminum chloride solution sample and the wastewater in each glass container, then detect the quality of the wastewater in each glass container by the wastewater detector to obtain the corresponding quality parameters, and obtain the corresponding quality parameters of the wastewater sample; Then calculate the corresponding quality parameters of the wastewater in each glass container with the corresponding quality parameters of the wastewater sample to obtain the corresponding purification ratio L.

2. The process for preparing a polyaluminum chloride solution as claimed in claim 1, wherein: In the second step, the molar ratio of aluminum hydroxide to dilute hydrochloric acid solution is 1:

3.

3. The process for preparing a polyaluminum chloride solution as claimed in claim 1, wherein: The reaction equation in the second step is: Al(OH)3+3HCl=AlCl3+3H2O.

4. The process for preparing a polyaluminum chloride solution as claimed in claim 1, wherein: The calculation method of the purification ratio is obtained by the formula L=Cq / (Cy-C0), wherein Cq represents the corresponding mass parameter of the wastewater in each glassware, Cy represents the corresponding mass parameter of the wastewater sample, and C0 is a preset value, which represents the mass parameter corresponding to the wastewater treatment discharge standard.

5. A purification process of a polyaluminum chloride solution as a water purifying agent, which is carried out using a polyaluminum chloride solution obtained by the process for producing a polyaluminum chloride solution as a water purifying agent according to any one of claims 1 to 4, characterized in that, The process comprises the following modes: S1, first, a specified amount of polyaluminum chloride mother liquor is put into a certain amount of wastewater; S2, then the polyaluminum chloride mother liquor reacts with the wastewater to obtain aluminum hydroxide and a small amount of dilute hydrochloric acid solution, so that the wastewater is acidic; S3, at the same time, calcium carbonate reacts with a small amount of dilute hydrochloric acid solution to generate carbon dioxide gas and calcium ions; S4, then the polyaluminum chloride sub-liquid is added to the wastewater; S5, then the polyaluminum chloride sub-liquid reacts with the aluminum hydroxide obtained in step S2 to generate sodium meta-aluminate; S6, then the sodium meta-aluminate reacts with the calcium ions obtained in step S3 to generate calcium meta-aluminate and precipitate.

6. The purification process of a polyaluminum chloride solution as a water purifying agent according to claim 5, characterized in that: The ion reaction mode in step S2 is: Al 3+ + 3H2O ⇔ Al(OH)3 + 3H + .

7. The purification process of a polyaluminum chloride solution as a water purifying agent according to claim 5, characterized by: Ion reaction equation in step S3: CaCO3+ 2H + = CO2↑+ H2O + Ca 2+ .

8. The purification process of a polyaluminum chloride solution as a water purifying agent according to claim 5, characterized by: The carbon dioxide gas obtained in step S3 is used to assist the diffusion of the unreacted polyaluminum chloride mother liquor and polyaluminum chloride sub-liquid in the wastewater.

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