KR102567638B1 - Water treatment method to reduce residual aluminum - Google Patents

Abstract

The present invention relates to a method for reducing aluminum by water treatment. In order to solve conventional problems such as residual unreacted substances and additional facilities, a coagulant is prepared by mixing sulfuric acid, aluminum hydroxide and water in a certain ratio, and the coagulant is prepared alone. It is an invention capable of minimizing residual aluminum without additional materials or additional equipment by treatment or combined treatment with an inorganic coagulant and/or an organic coagulant.

Description

Water treatment method to reduce residual aluminum}

The present invention relates to a method for reducing aluminum by water treatment, wherein sulfuric acid, aluminum hydroxide, and water are mixed and reacted at a certain ratio to prepare a coagulant, and raw water is treated alone or in combination with an inorganic coagulant to minimize residual aluminum. It's about how to do it.

Aluminum accounts for about 8% by weight of soil components and is a silvery-white, soft metal constituting the structure of rocks and animals and plants. Aluminum has a tendency to form precipitates in water or to be adsorbed in the form of hydroxides, carbonates, etc., so aluminum is used as a coagulant in water purification plants.

Coagulants containing aluminum include aluminum sulphate, sodium aluminate, aluminum ammonium sulphate, and potash alum as monomolecular inorganic coagulants. Poly Aluminum Chloride, Poly Alumium Sulfate, Poly Aluminum Sulfate Silicate, and Poly Aluminum Hydroxy Chloro Sulfate.

Regarding aluminum, there is a report that, although controversial, it is associated with Alzheimer's disease, a type of dementia. Accordingly, it has been pointed out that the total aluminum level, including monomeric aluminum and other forms of aluminum in water, should be 200 mg or less per liter. In drinking water quality standards, the maximum recommended value of aluminum in drinking water is set at 0.2 mg per liter, and in Korea, the above standards are set according to the Drinking Water Management Act.

In the case of Korea, since there has been little rain for the past 5 years, the pH of raw water has risen nationwide, and in the case of spring or autumn, the pH rises to 9.5, resulting in a problem that a large amount of residual aluminum is generated in water purification plants using high-salinity airways. are doing It is inevitable to use aluminum-based coagulants such as aluminum sulfate in water purification facilities, and many high-salt air coagulants are used for efficient water treatment such as turbidity and organic matter removal. ₂ It is based on the method through the treatment facility, but there are limitations due to unreaction of hazardous chemicals, design cost, and design capacity. In particular, in the case of sulfuric acid and hydrochloric acid, if they are 10% or more, they are hazardous chemicals, and when used in water treatment, safety problems for workers may occur, so most water treatment plants use 9% hydrochloric acid and sulfuric acid to lower the pH. As hydrochloric acid and sulfuric acid of low concentration are used, the amount of input increases, and accordingly, it is difficult to manage the storage tank.

In the case of conventional aluminum sulfate (Aluminum Sulfate), it exists in a solid or liquid phase, and the aluminum oxide content is used at 16% or more in the case of solid phase and 8% or more in the case of liquid phase. A liquid phase is mainly used for ease of quantitative input, and the agglutination reaction is performed in the following manner.

Al ₂ (SO ₄ ) + 2H ₂ PO ₄ ^- + 4HCO ₃ ^- → 2AlPO ₄ + 3SO ₄ ^2- + 4H ₂ CO ₃

In this regard, there are Korean Patent Publication No. 10-0318661 regarding a wastewater treatment agent containing calcium carbonate and calcium chloride, and Korean Patent Publication No. 1999-0014376 regarding a wastewater treatment agent containing a large amount of fluorine, and Korean Patent Publication No. 2019 -0115868 discloses an aluminum sulfate-based inorganic coagulant using a waste sulfuric acid solution, and Korean Patent Registration No. 10-1159236 discloses a method for manufacturing a low-salt air polyaluminum chloride coagulant and a water treatment method using the same, for eutrophication such as algal bloom. A low basicity polyaluminum chloride (PACB) coagulant with 10-20% basicity and 8-15% Al ₂ O ₃ that can be prevented and stored for a long time is disclosed, and Korean Patent No. 10-1640368 discloses Al ₂ O ₃ Disclosed is a method for producing a coagulant that maintains a low basicity of 7 to 15% by weight and 1 to 5% by weight of Fe content and a wastewater treatment method through the same.

In general, most of the inorganic coagulants are aluminum-based coagulants, and as the coagulant is added rather than aluminum contained in actual raw water, aluminum remaining after combining with the colloid is dissolved in water, which causes a problem in eluting aluminum.

In particular, this aluminum elution problem begins to occur when the pH of the raw water is higher than 7.5, and the higher the pH of the raw water, the greater the aluminum elution problem. Even if the minimum coagulant is added for coagulation, if the pH of the raw water is high, aluminum is detected above the standard value in the treated water even if coagulation is achieved. Efforts have been made to reduce aluminum, but there is no effect of reducing residual aluminum in raw water with high pH.

In addition, as a pH control method to solve the problem of aluminum elution, a method of using carbon dioxide or injecting an excessive amount of coagulant is being tried, but in the case of injecting carbon dioxide, it is difficult in terms of operation management, cost, and efficiency in the actual process There is a problem in that, when an excessive amount of coagulant is used, the amount of sludge generated increases and residual aluminum may further increase as the input amount increases.

Accordingly, the inventors of the present invention have made efforts to solve the above problems, and as a result, even if a conventional coagulant is used, when the pH is lowered to 7.5 or less by adding a certain amount of the composition according to the present invention, the generation of residual aluminum is reduced, and a smaller amount is added than sulfuric acid or hydrochloric acid. However, the present invention was completed by revealing that the pH can be lowered to 7.5 or less, the residual aluminum is detected lower, and the coagulation efficiency can be expected while reducing the residual aluminum even when added alone.

Korean Patent Publication No. 1999-0014376 Korean Patent Publication No. 2019-0115868 Republic of Korea Patent No. 10-0318661 Korean Registered Patent No. 10-1640368

Konkuk University master's thesis, Youngsong Ko et al., 1993.02, Consideration of influence factors to minimize residual aluminum concentration in water treatment

In the present invention, when using a conventional coagulant, in order to solve the problem of increasing residual aluminum as the coagulant is added in raw water with a high pH, aluminum is reduced by performing water treatment capable of reducing aluminum while using the inorganic coagulant and / or organic coagulant as it is. provides a way

In order to achieve the above object, the present invention a) prepares a coagulant by mixing sulfuric acid, aluminum hydroxide and water, but 10 to 35% by weight of sulfuric acid, 0.5 to 12% by weight of aluminum hydroxide and 55 to 85% by weight of water relative to the total weight of the coagulant Mixing % to prepare a coagulant; and b1) adding the coagulant of step a) alone to raw water or b2) adding the coagulant of step a) to raw water in combination with one or more coagulants selected from the group consisting of aluminum-based coagulants and organic coagulants; Including, here, the coagulant of step a) provides a method for reducing aluminum by water treatment comprising aluminum oxide and sulfate ions.

In one aspect of the present invention, the coagulant of step a) has a sulfate ion content of 10 to 40% by weight and an aluminum oxide content of 0.5 to 5% by weight based on the total weight of the coagulant.

In one aspect of the present invention, the coagulant of step a) is sulfide, chloride, silicate, oxide; and one or more compounds selected from the group consisting of salts thereof.

In one aspect of the present invention, the coagulant of step a) further comprises at least one compound selected from the group consisting of Group 2A compounds, Group 3A compounds, Group 4A compounds, Group 3B compounds, Group 4B compounds, and salts thereof. In a specific aspect of the present invention, the coagulant of step a) is Group 2A chloride, Group 2A sulfide, Group 3B chloride, Group 3B sulfide, Group 4B chloride, Group 4B sulfide, sodium silicate (Na ₂ SiO ₃ ) and salts thereof. It further includes one or more compounds selected from the group consisting of.

Further, in one aspect of the present invention, the inorganic coagulant of step b2) is an aluminum-based coagulant, an iron salt-based coagulant, or a mixed coagulant thereof.

In one aspect of the present invention, the inorganic coagulant of step b2) is aluminum chloride, aluminum sulfate, polyaluminum sulfate, polyaluminum chloride, polyaluminum polysulfate silicate, polychlorinated aluminum silicate, polyhydroxochlorinated aluminum silicate, polyaluminum polysulfate silicate and poly It is at least one selected from the group consisting of hydroxychlorinated aluminum sulfate.

In a specific aspect of the present invention, the inorganic coagulant of step b2) has an aluminum oxide content of 5 to 25% based on the total weight of the inorganic coagulant.

In one aspect of the present invention, the organic coagulant of step b2) is polyacrylamide-based, polyvinylamine-based, polyallylamine-based, polyethyleneamine-based, polyamine-based, polyacrylic ester-based, polyethyleneimine-based, polydead film and these It is at least one selected from the group consisting of mixed coagulants.

In one aspect of the present invention, in the method for reducing aluminum, the turbidity of treated water after treatment is 2 NTU or less. In a specific aspect of the present invention, in the method for reducing aluminum, the turbidity of treated water after treatment is 1 NTU or less.

In one aspect of the present invention, in the aluminum reduction method, the pH of the treated water after treatment is 8.5 or less. In a specific aspect of the present invention, the aluminum reduction method has a pH of 7.0 to 8.0 of treated water after treatment.

In one aspect of the present invention, the aluminum method reduces residual aluminum by 5 to 90% compared to the case where the coagulant of step a) is not introduced.

In addition, the present invention includes aluminum sulfate, aluminum oxide and water, the content of sulfate ions in the aluminum sulfate is 10 to 40% by weight relative to the total weight of the coagulant, and the aluminum oxide content is 0.5 to 5% by weight relative to the total weight of the coagulant. A water treatment coagulant for abatement is provided.

In one aspect of the present invention, the water treatment coagulant for aluminum reduction is sulfide, chloride, silicate, oxide; and one or more compounds selected from the group consisting of salts thereof.

In one aspect of the present invention, the water treatment coagulant for reducing aluminum further comprises at least one compound selected from the group consisting of Group 2A compounds, Group 3A compounds, Group 4A compounds, Group 3B compounds, Group 4B compounds, and salts thereof. In one specific aspect of the present invention, the water treatment coagulant for reducing aluminum is group 2A chloride, group 2A sulfide, group 3B chloride, group 3B sulfide, group 4B chloride, group 4B sulfide, sodium silicate (Na ₂ SiO ₃ ) and salts thereof. It further includes one or more compounds selected from the group consisting of.

In addition, in one aspect of the present invention, the water treatment coagulant for reducing aluminum further includes an inorganic coagulant or an organic coagulant.

The present invention is a treatment method capable of minimizing residual aluminum during water treatment using a coagulant containing sulfuric acid and aluminum hydroxide, and the residual aluminum is reduced by both a method of adding the coagulant alone and a method of adding the coagulant in combination with an inorganic and/or organic coagulant. It can be reduced and has the advantage of not requiring additional materials or equipment.

In addition, since the present invention has an effect of reducing pH and alkalinity, it can be used as a substitute for sulfuric acid and hydrochloric acid for reducing conventional pH. Conventionally, when the concentration of sulfuric acid and hydrochloric acid is 10% or more, there is a problem that it is very toxic to the human body as a hazardous chemical substance. It has the advantage of increasing efficiency.

Hereinafter, the present invention will be described in detail.

In the present invention, a) a coagulant is prepared by mixing sulfuric acid, aluminum hydroxide and water, but the coagulant is prepared by mixing 10 to 35% by weight of sulfuric acid, 0.5 to 12% by weight of aluminum hydroxide, and 55 to 85% by weight of water relative to the total weight of the coagulant. doing; and b1) adding the coagulant of step a) alone, or b2) adding the coagulant of step a) in combination with at least one coagulant selected from the group consisting of inorganic coagulants and organic coagulants; Here, the coagulant of step a) relates to a method of reducing aluminum by performing water treatment containing aluminum oxide and sulfate ions.

In this specification, the compound has the same meaning as commonly understood in the art to which the present invention belongs. In addition, water treatment in the present specification is a process of removing contaminants in raw water, and has the same meaning as commonly understood in the art to which the present invention belongs.

In the present invention, steps b1) and b2) may be performed sequentially, or steps b1) or b2) may be performed alone or together, and the order of steps b1) and b2) is not limited. In the present invention, when the inorganic coagulant of step b2) is used alone, the residual aluminum is remarkably high, so it can be used in combination with the coagulant of the present invention to achieve high efficiency in water treatment such as phosphorus and sulfur removal and low residual aluminum. there is.

In the present invention, when one or more coagulants selected from the group consisting of the inorganic coagulant and the organic coagulant of step b2) are used in combination, this means that the coagulant of step a) and the inorganic coagulant and organic coagulant are used in combination, and a case in which the coagulant of step a) and the inorganic coagulant, or the coagulant of step a) and the organic coagulant are used in combination.

In addition, when used in combination in the present invention, it includes not only the case of separately using each of the separate coagulants, but also the use of each coagulant in the form of a mixture of coagulants. For example, the coagulant of step a) and polyaluminum hydroxide may be mixed and exist as one solution or powder form, and both when it is added to raw water and when each component is separated and used together Applies to concomitant use.

In the present invention, the coagulant has other effects such as KMnO ₄ , turbidity improvement, pH reduction, etc. in addition to the aluminum reduction effect, and the treatment method of the present invention is not limited to the aluminum reduction effect. Therefore, as a use for lowering pH when pH and alkalinity are high, it may be used as a substitute for sulfuric acid and hydrochloric acid.

In the present invention, in step a), the sulfuric acid concentration may be 97 to 99%, and the aluminum oxide concentration of the aluminum hydroxide may be 55 to 65%. In the present invention, sulfuric acid and aluminum hydroxide may be mixed with water, and when sulfuric acid or aluminum hydroxide is dissolved in water and mixed with water, a range other than the above concentration may be used. For example, when using a sulfuric acid concentration of 70%, the coagulant can be prepared by increasing the input amount compared to the case of a sulfuric acid concentration of 97%, and if the properties of the coagulant are the same, any concentration may be used. However, when the sulfuric acid concentration is 95% or more, the coagulant can be generated in a short time through an exothermic reaction with aluminum hydroxide.

In one aspect of the present invention, the coagulant of step a) has a sulfate ion content of 10 to 40% by weight and an aluminum oxide content of 0.5 to 5% by weight based on the total weight of the coagulant. In a specific aspect of the present invention, the coagulant of step a) has a sulfate ion content of 10 to 30% by weight and an aluminum oxide content of 1 to 3% by weight based on the total weight of the coagulant. In the present invention, the content of sulfate ions and aluminum oxide in the coagulant has the main characteristics, and it is not sufficient to dissolve aluminum oxide, so that the coagulant is not made and Al is not removed, and if the sulfate ion exceeds 40%, the unreacted Residual sulfate ions may be toxic, and additional treatment may be required. In addition, when the concentration of aluminum oxide is less than 0.5%, there is no cohesive ability, and when the concentration is 6% or more, the residual aluminum increases, which may cause an effect different from the object of the present invention.

In addition, in the present invention, the coagulant of step a) further comprises other types of compounds such as materials other than sulfate ions and aluminum oxide, for example, sulfides of Group 2A metals, chlorides of Group 3B metals, sulfides of Group 4B metals, and the like. can do. For more specific examples, calcium chloride (CaCl ₂ ) as a chloride of a Group 2A metal, gallium sulfate (Ga ₂ (SO ₄ ) ₃ ) as a Group 3A compound, sodium silicate (Na ₂ SiO ₃ ) as a Group 4A compound, and a Group 4A compound Examples thereof include potassium silicate (K ₂ SiO ₃ ) and zeolite, which are exemplary and not limited thereto.

In one aspect of the present invention, the coagulant of step a) is sulfide, chloride, silicate, oxide; And it may further include one or more compounds selected from the group consisting of salts thereof, more specifically from the group consisting of Group 2A compounds, Group 3A compounds, Group 4A compounds, Group 3B compounds, Group 4B compounds, and salts thereof. It may further include one or more selected compounds. More specifically, at least one compound selected from the group consisting of Group 2A chloride, Group 2A sulfide, Group 3B chloride, Group 3B sulfide, Group 4B chloride, Group 4B sulfide, sodium silicate (Na ₂ SiO ₃ ) and salts thereof can include more.

In the present invention, the coagulant of step a) further includes not only compounds such as the Group 2A compound and Group 3A compound, but also organic coagulants such as polyacrylamide and polyvinylamine and/or inorganic coagulants such as aluminum. can be in the form

In the present invention, the inorganic coagulant of step b2) may be an aluminum-based coagulant, an iron salt-based coagulant, or a mixed coagulant thereof. Aluminum-based coagulants include, for example, aluminum sulfate (Alum), poly aluminum chloride, and the like, and iron-salt-based coagulants include ferric chloride (FeCl ₃ ), ferrous chloride (FeCl ₂ ), and sulfuric acid. Ferric sulfate (Fe ₂ (SO ₄ ) ₃ ), ferrous sulfate (Fe(SO) ₄ ), polyferric chloride (PFC), polyferric sulfate (PFS), polysilicate ( polysilicate iron) and the like, and in the present invention, the aluminum-based coagulant and the iron-salt-based coagulant are not limited to the above examples. In addition, these mixed coagulants refer to coagulants having both aluminum-based and iron-salt-based coagulants, and examples thereof include polyaluminum iron chloride, aluminum iron, polychlorinated aluminum iron sulfate, and the like.

In a specific aspect of the present invention, the inorganic coagulant of step b2) is aluminum chloride, aluminum sulfate, polyaluminum sulfate, polyaluminum chloride, polyaluminum polysulfate silicate, polychlorinated aluminum silicate, polyhydroxide aluminum silicate aluminum, polysulfate aluminum silicate and It is at least one selected from the group consisting of polyhydroxide chloride aluminum sulfate. In a more specific aspect of the present invention, the inorganic coagulant in step b2) is polyaluminum chloride or polyaluminum hydroxide chloride sulfate.

In one aspect of the present invention, the inorganic coagulant of step b2) has an aluminum oxide content of 5 to 25% based on the total weight of the inorganic coagulant. In one specific aspect of the present invention, the inorganic coagulant has an aluminum oxide content of 7 to 20% relative to the total weight of the coagulant.

In the present invention, the organic coagulant of step b2) is a polyacrylamide-based, polyvinylamine-based, polyallylamine-based, polyethyleneamine-based, polyamine-based, polyacrylic ester-based, polyethyleneimine-based, polydead film, and mixed coagulants thereof. It may be one or more selected from the group consisting of.

In one aspect of the present invention, in the method for reducing aluminum, the turbidity of treated water after treatment is 2 NTU or less. In a specific aspect of the present invention, the aluminum reduction method may have a turbidity of 1.5 NTU or less of treated water after treatment. In a specific aspect of the present invention, in the aluminum reduction method according to step b1) or step b2), the treated water may have a turbidity of 1.5 NTU or less after treatment. In a more specific aspect of the present invention, in the aluminum reduction method according to step b1) or step b2), the turbidity of the treated water after treatment may be 1.0 NTU or less.

In one aspect of the present invention, the aluminum reduction method is to introduce the pH to 8.5 or less. In addition, in the present invention, the pH may be added up to 8.5 or less in step b1) or b2). In a specific aspect of the present invention, in the aluminum reduction method, the pH of the treated water after treatment is 8.0 or less. In a more specific aspect of the present invention, the aluminum reduction method has a pH of 7.0 to 8.0 of treated water after treatment.

Through the aluminum reduction method of the present invention, it is possible to simultaneously achieve turbidity and pH conditions, and at the same time, aluminum treatment is possible, thereby showing excellent effects. In addition, the aluminum reduction method of the present invention can achieve a desired pH condition even if an amount smaller than the amount of hydrochloric acid and sulfuric acid normally added to lower the pH is administered.

In one aspect of the present invention, the aluminum reduction method can reduce the residual aluminum by 5 to 90% compared to the case where the coagulant of step a) is not introduced. In a more specific aspect of the present invention, residual aluminum may be reduced to 10 to 70%.

In addition, the aluminum sulfate content of sulfate ions is 10 to 40% by weight based on the total weight of the coagulant, and the aluminum oxide content is 0.5 to 5% by weight based on the total weight of the coagulant.

In one aspect of the present invention, the water treatment coagulant for aluminum reduction is sulfide, chloride, silicate, oxide; And it may further include one or more compounds selected from the group consisting of salts thereof, more specifically from the group consisting of Group 2A compounds, Group 3A compounds, Group 4A compounds, Group 3B compounds, Group 4B compounds, and salts thereof. It may further include one or more selected compounds. More specifically, at least one compound selected from the group consisting of Group 2A chloride, Group 2A sulfide, Group 3B chloride, Group 3B sulfide, Group 4B chloride, Group 4B sulfide, sodium silicate (Na ₂ SiO ₃ ) and salts thereof can include more.

In addition, in one aspect of the present invention, the water treatment coagulant for reducing aluminum may further include an inorganic coagulant or an organic coagulant. In one specific aspect of the present invention, the inorganic coagulant is aluminum chloride, aluminum sulfate, polyaluminum sulfate, polyaluminum chloride, polysulfuric acid aluminum silicate, polychlorinated aluminum silicate, polyhydroxide chloride silicate aluminum, polysulfate aluminum silicate and polyhydroxide chloride It may be at least one selected from the group consisting of aluminum sulfate, and in a specific aspect of the present invention, the organic coagulant is polyacrylamide-based, polyvinylamine-based, polyallylamine-based, polyethyleneamine-based, polyamine-based, polyacrylic ester It may be at least one selected from the group consisting of a coagulant-based, polyethyleneimine-based, polydead film, and mixed coagulants thereof.

In addition, in the present invention, the coagulant for reducing aluminum further comprises not only compounds such as the group 2A compound and the group 3A compound, but also organic coagulants such as polyacrylamide and polyvinylamine and/or inorganic coagulants such as aluminum. can be in the form

Hereinafter, the present invention will be described in detail by examples and experimental examples.

However, the following Examples and Experimental Examples are merely illustrative of the present invention, and the contents of the present invention are not limited to the following Examples and Experimental Examples.

<Example 1> Preparation of sulfuric acid-based coagulant

As shown in Table 1 below, a sulfuric acid-based coagulant was prepared by adjusting the composition ratio of aluminum hydroxide, sulfuric acid and water. Specifically, for the properties of the manufacturing raw material, aluminum oxide concentration of 63% of aluminum hydroxide and sulfuric acid (H ₂ SO ₄ ) concentration of 98% were used, and by varying the manufacturing ratio, the sulfate ion concentration of 10 to 30%, aluminum oxide (Al ₂ O ₃ ) A coagulant was prepared to have a concentration of 0.5 to 7%.

Specifically, 0.5 to 12% by weight of aluminum hydroxide (Al(OH) ₃ ), which is 63% of aluminum oxide, and 25 to 40% by weight of water were mixed, transferred to a reactor, and mixed. Thereafter, 10 to 35% by weight of sulfuric acid having a concentration of 98% was added to the mixture and reacted at a temperature of 120 to 150 ° C. (reaction heat) for 30 to 80 minutes. A reactant was collected, sulfuric acid and aluminum hydroxide were added according to the pH, and when the pH was adjusted, 30 to 45% by weight of water was added to adjust the concentration, followed by filtration to prepare a coagulant. (Here, each weight % represents the weight % relative to the total amount used)

Example S 0.5 S1 S3 S5 S6 S7 1) 10% sulfate ion concentration appearance Al ₂ O ₃ (%) 0.5 One 3 5 6 7 Sulfate ion (%) 10 manufacturing rate aluminum hydroxide 8 17 50 83 100 117 sulfuric acid 104 water 888 879 846 813 796 779 2) 20% sulfate ion concentration appearance Al ₂ O ₃ (%) 0.5 One 3 5 6 7 Sulfate ion (%) 20 manufacturing rate aluminum hydroxide 8 17 50 83 100 117 sulfuric acid 208 water 784 775 742 709 692 675 3) 30% sulfate ion concentration appearance Al ₂ O ₃ (%) 0.5 One 3 5 6 7 Sulfate ion (%) 30 manufacturing rate aluminum hydroxide 8 17 50 83 100 117 sulfuric acid 313 water 679 670 637 604 587 570

<Experimental Example 1> Residual aluminum reduction effect of sulfuric acid-based coagulant

<Experimental Example 1-1> Reducing effect of coagulant at 10% sulfate ion concentration

The sulfuric acid-based coagulant prepared in Example 1 was collected from water from A water purification plant and subjected to a coagulation test using a Jar-test. The properties of the raw water used in the flocculation experiment, the amount of coagulant and the input results are shown in Table 2.

9% sulfuric acid Example S 0.5 S1 S3 S5 S6 S7 appearance Al ₂ O ₃ (%) - 0.5 One 3 5 6 7 Sulfate ion (%) - 10 Dosage (ppm) 75 70 pH 7.19 7.19 7.20 7.22 7.20 7.18 7.20 Turbidity (NTU) 1.71 1.25 1.17 1.04 0.938 0.881 0.810 Alkalinity (mg/l) 14.5 14.3 14.3 14.4 14.4 14.2 14.1 KMnO ₄ (mg/l) 16.7 12.5 11.8 10.8 9.4 8.2 7.5 Al (mg/l) 0.022 0.017 0.014 0.018 0.020 0.038 0.055 raw water properties pH 8.34, Turbidity 1.87NTU, Alkalinity 18.4mg/l, KMnO ₄ 17.0mg/l, Al 0.023mg/l

<Experimental Example 1-2> Reducing effect of coagulant at 20% sulfate ion concentration

The sulfuric acid-based coagulant prepared in Example 1 was collected from water from A water purification plant and subjected to a coagulation test using a Jar-test. The properties of the raw water used in the flocculation experiment, the amount of coagulant and the input results are shown in Table 3.

9% sulfuric acid Example S 0.5 S1 S3 S5 S6 S7 appearance Al ₂ O ₃ (%) - 0.5 One 3 5 6 7 Sulfate ion (%) - 20 Dosage (ppm) 75 40 pH 7.21 7.20 7.21 7.20 7.21 7.19 7.21 Turbidity (NTU) 1.75 1.34 1.25 1.18 1.02 0.921 0.872 Alkalinity (mg/l) 14.4 14.4 14.3 14.3 14.3 14.4 14.2 KMnO ₄ (mg/l) 16.9 13.1 12.4 11.2 9.5 8.7 7.9 Al (mg/l) 0.023 0.021 0.017 0.016 0.019 0.028 0.035 raw water properties pH 8.32, Turbidity 1.81NTU, Alkalinity 18.2mg/l, KMnO ₄ 17.3mg/l, Al 0.023mg/l

<Experimental Example 1-3> Reducing effect of coagulant at 30% sulfate ion concentration

The sulfuric acid-based coagulant prepared in Example 1 was collected from water from A water purification plant and subjected to a coagulation test using a Jar-test. The properties of the raw water used in the flocculation experiment, the amount of coagulant and the input results are shown in Table 4.

9% sulfuric acid Example S 0.5 S1 S3 S5 S6 S7 appearance Al ₂ O ₃ (%) - - 0.5 One 3 5 6 Sulfate ion (%) - 30 Dosage (ppm) 75 25 pH 7.20 7.20 7.21 7.21 7.22 7.20 7.20 Turbidity (NTU) 1.78 1.44 1.35 1.24 1.10 0.997 0.923 Alkalinity (mg/l) 14.3 14.3 14.2 14.4 14.3 14.2 14.2 KMnO ₄ (mg/l) 16.5 13.5 12.7 11.9 10.1 9.2 8.5 Al (mg/l) 0.023 0.018 0.014 0.015 0.020 0.029 0.036 raw water properties pH 8.28, Turbidity 1.89NTU, Alkalinity 18.1mg/l, KMnO ₄ 17.5mg/l, Al 0.022mg/l

As shown in Tables 2, 3 and 4, in the case of 9% sulfuric acid, there was no flocculation ability, so turbidity, KMnO ₄ , aluminum, etc. were not removed, and the higher the concentration of aluminum oxide, the better the water treatment efficiency. In addition, it was confirmed that the higher the concentration of sulfate ion, the smaller the amount of coagulant required for pH control. In addition, when the concentration of aluminum oxide was 0.5 to 5%, the residual aluminum was detected lower than that of raw water, indicating that the residual aluminum reduction effect was excellent. However, when the aluminum oxide concentration was 6% or more, residual aluminum higher than that of raw water was detected, confirming that there was no effect of reducing residual aluminum.

<Experimental Example 2> Residual aluminum reduction effect of sulfuric acid-based coagulant containing additives

After adding additives (group 2A, 3A, 4A, 3B, 4B materials) to the sulfuric acid-based coagulant prepared by the method of Example 1, water from the H water purification plant was collected and coagulated using a Jar-test. An experiment was conducted. The properties of the raw water used in the coagulation experiment, the amount of coagulant, the type of additives, and the input results are shown in Table 5.

9% sulfuric acid Examples (+ additives) not added Group 2A Group 3A Group 4A Group 3B Group 4B Dosage (ppm) 95 45 pH 7.11 7.07 7.09 7.09 7.08 7.11 7.09 Turbidity (NTU) 2.89 0.901 0.891 0.893 0.890 0.897 0.892 Al (mg/l) 0.026 0.022 0.018 0.019 0.017 0.018 0.017 note 1) Raw water properties: pH 8.59, turbidity 3.21NTU, Al 0.028mg/l
2) Sulfuric acid-based coagulant properties: Al ₂ O ₃ 4.5% sulfate ion 18%
3) Additive properties
- Group 2A material: Add 0.5% by weight of CaCl ₂
- Group 3A material: Add 0.5% by weight of Ga ₂ (SO ₄ ) ₃
- Group 4A material: Add 0.5% by weight of Na ₂ SiO ₃
- Group 3B material: Add 0.5% by weight of YCl ₃ 6H ₂ O
- Group 4B material: Add 0.5% by weight of ZrCl ₄

As shown in Table 5, in the case of 9% sulfuric acid, there was no aggregation ability, so turbidity, aluminum, etc. were not reduced. In addition, it was confirmed that when the additive was further included in the sulfuric acid-based coagulant, the turbidity removal efficiency and the residual aluminum reduction effect were more excellent than when the additive was not included. In addition, it was confirmed that there was no significant change in water treatment efficiency even when the types of additives were different.

<Experimental Example 3> Residual aluminum reduction effect of sulfuric acid-based coagulant containing additives

After further including an additive (polyamine as an organic coagulant) in the sulfuric acid-based coagulant by the method of Example 1, water from the I water purification plant was sampled and a coagulation experiment was conducted using a Jar-test. The properties of the raw water used in the flocculation experiment, the amount of coagulant, the mixing ratio of additives, and the input results are shown in Table 6.

9% sulfuric acid Examples (+ Polymer mixing ratio) 0% 0.5% One% 3% 5% 7% Dosage (ppm) 75 35 35 35 35 35 35 pH 7.09 7.05 7.07 7.12 7.15 7.17 7.27 Turbidity (NTU) 3.81 1.27 1.00 0.967 0.853 0.795 0.738 Al (mg/l) 0.027 0.023 0.021 0.019 0.017 0.017 0.026 note 1) Raw water properties: pH 8.42, turbidity 4.13NTU, Al 0.027mg/l
2) Sulfuric acid-based coagulant properties: Al ₂ O ₃ 3.5% sulfate ion 23%
3) Additive properties: Polymer - Polyamine

As shown in Table 6, in the case of 9% sulfuric acid, there was no coagulation ability, so turbidity, aluminum, etc. were not reduced. In addition, in the case of a product in which a polymer was mixed with a sulfuric acid-based coagulant, the turbidity removal efficiency was excellent as the mixing ratio of the polymer increased, but it was confirmed that the residual aluminum reduction effect was lowered when the mixture was mixed in excess of 7%. The higher the concentration of aluminum oxide, the better the water treatment efficiency. In addition, it was confirmed that the higher the concentration of sulfate ions, the smaller the amount of coagulant required for pH control.

<Experimental Example 4> Residual aluminum reduction effect of sulfuric acid-based coagulant containing additives

After adding additives (group 4A, group 4B material, polymer) to the sulfuric acid-based coagulant by the method of Example 1, water from the J water purification plant was sampled and a coagulation experiment was conducted using a Jar-test. The properties of the raw water used in the flocculation experiment, the amount of coagulant, the type of additives, and the input results are shown in Table 7.

9% sulfuric acid Examples (+ additives) not added Group 4A Group 4B Dosage (ppm) 190 85 85 85 pH 7.11 7.12 7.14 7.13 Turbidity (NTU) 3.02 0.921 0.913 0.915 Al (mg/l) 0.023 0.020 0.018 0.017 note 1) Raw water properties: pH 9.05, turbidity 3.28NTU, Al 0.024mg/l
2) Sulfuric acid-based coagulant properties: Al ₂ O ₃ 4% sulfate ion 23%
3) Additive properties
- Group 4A material: Add 0.5% by weight of Na ₂ SiO ₃
- Group 4B material: Add 0.5% by weight of ZrCl ₄
- Polymer: 3 parts by weight of PolyDADMAC added

As shown in Table 7, in the case of 9% sulfuric acid, there was no coagulation ability, so turbidity, aluminum, etc. were not reduced. In addition, it was confirmed that when the additive was further included in the sulfuric acid-based coagulant, the turbidity removal efficiency and the residual aluminum reduction effect were more excellent than when the additive was not included. In addition, it was confirmed that there was no significant change in water treatment efficiency even when the types of additives were different.

<Experimental Example 5> Residual aluminum reduction effect when used in combination with sulfuric acid-based coagulants

<Experimental Example 5-1> Reducing effect of coagulant at 10% sulfate ion concentration

The sulfuric acid-based coagulant prepared in Example 1 was collected from water from B water purification plant and a coagulation experiment was conducted using a Jar-test. The effect of reducing residual aluminum was confirmed by adding it in combination with polyhydroxychlorinated aluminum sulfate, and the properties of the raw water used in the coagulation experiment, the coagulant properties, the coagulant input amount, and the input results are shown in Table 8.

In the case of parallel introduction, polyhydroxyaluminum chloride sulfate was selected among the aluminum-based coagulants, and the higher the pH decrease, the higher the aluminum was detected.

not input 9% sulfuric acid Example S 0.5 S1 S3 S5 S6 S7 appearance Al ₂ O ₃ (%) - - 0.5 One 3 5 6 7 Sulfate ion (%) - - 10 Dosage (ppm) - 75 70 coagulant Aluminum polyhydrochloride sulfate Dosage (ppm) 13ppm pH 7.89 7.11 7.11 7.10 7.08 7.09 7.11 7.10 Turbidity (NTU) 0.615 0.391 0.273 0.250 0.249 0.247 0.251 0.252 Alkalinity (mg/l) 17.4 13.6 13.5 13.7 13.5 13.6 13.7 13.7 KMnO ₄ (mg/l) 7.3 5.6 4.5 4.3 4.2 4.0 4.1 4.1 Al (mg/l) 0.157 0.120 0.079 0.083 0.089 0.094 0.131 0.142 note 1) Raw water properties: pH 8.37, turbidity 1.99NTU, alkalinity 18.2mg/l, KMnO ₄ 17.0mg/l, Al 0.022mg/l
2) Coagulant properties: Polyhydrochlorinated aluminum sulfate Al ₂ O ₃ 10.5%, Basicity 70.3%

<Experimental Example 5-2> Reducing effect of coagulant at 20% sulfate ion concentration

The sulfuric acid-based coagulant prepared in Example 1 was collected from water from B water purification plant and a coagulation experiment was conducted using a Jar-test. The effect of reducing residual aluminum was confirmed by adding it in combination with polyhydroxychlorinated aluminum sulfate.

not input 9% sulfuric acid Example S 0.5 S1 S3 S5 S6 S7 appearance Al ₂ O ₃ (%) - - 0.5 One 3 5 6 7 Sulfate ion (%) - - 20 Dosage (ppm) - 75 40 coagulant Aluminum polyhydrochloride sulfate Dosage (ppm) 13ppm pH 7.85 7.10 7.09 7.09 7.10 7.09 7.10 7.11 Turbidity (NTU) 0.612 0.389 0.282 0.255 0.251 0.249 0.252 0.254 Alkalinity (mg/l) 17.3 13.7 13.6 13.6 13.7 13.7 13.6 13.8 KMnO ₄ (mg/l) 7.2 5.7 4.7 4.4 4.3 4.1 4.0 4.1 Al (mg/l) 0.153 0.118 0.073 0.080 0.086 0.091 0.126 0.138 note 1) Raw water properties: pH 8.27, turbidity 1.92NTU, alkalinity 18.1mg/l, KMnO ₄ 17.1mg/l, Al 0.024mg/l
2) Coagulant properties: Polyhydrochlorinated aluminum sulfate Al ₂ O ₃ 10.5%, Basicity 70.3%

<Experimental Example 5-3> Reduction effect of coagulant at 30% sulfate ion concentration

The sulfuric acid-based coagulant prepared in Example 1 was collected from water from B water purification plant and a coagulation experiment was conducted using a Jar-test. The effect of reducing residual aluminum was confirmed by adding it in combination with polyhydroxychlorinated aluminum sulfate.

not input 9% sulfuric acid Example S 0.5 S1 S3 S5 S6 S7 appearance Al ₂ O ₃ (%) - - 0.5 One 3 5 6 7 Sulfate ion (%) - - 30 Dosage (ppm) - 75 25 coagulant Aluminum polyhydrochloride sulfate Dosage (ppm) 13ppm pH 7.80 7.11 7.09 7.08 7.12 7.10 7.09 7.11 Turbidity (NTU) 0.618 0.391 0.285 0.268 0.259 0.253 0.248 0.249 Alkalinity (mg/l) 17.4 13.6 13.5 13.5 13.5 13.4 13.6 13.5 KMnO ₄ (mg/l) 7.5 5.8 4.9 4.5 4.3 4.2 4.1 4.2 Al (mg/l) 0.158 0.115 0.073 0.078 0.083 0.087 0.118 0.129 note 1) Raw water properties: pH 8.33, turbidity 2.01NTU, alkalinity 18.3mg/l, KMnO ₄ 17.2mg/l, Al 0.023mg/l
2) Coagulant properties: Polyhydrochlorinated aluminum sulfate Al ₂ O ₃ 10.5%, Basicity 70.3%

As shown in Tables 8, 9 and 10, when the present invention is used in combination with polyhydrochloride aluminum sulfate, which is a conventional coagulant, the effect of reducing residual aluminum, turbidity, KMnO ₄ , etc. is excellent, indicating that the water treatment efficiency is high. In addition, in the present invention, when the concentration of aluminum oxide is 0.5 to 5%, the residual aluminum is detected at a low level, and the residual aluminum reduction effect is confirmed to be excellent. It was confirmed that there was no effect of reducing residual aluminum.

<Experimental Example 6> Residual aluminum reduction effect when used in combination with sulfuric acid-based coagulants

Among the sulfuric acid-based coagulants prepared by the method of Example 1, the coagulant having a sulfate ion concentration of 21% and aluminum oxide (Al ₂ O ₃ ) concentration of 1 to 3% was collected from water from a C water purification plant, and a coagulation experiment using a Jar-test was performed. conducted. The effect of reducing residual aluminum was confirmed by adding it in combination with polyhydroxychlorinated aluminum sulfate.

In addition, raw water was measured at the rear of the aeration tank, pH, turbidity, alkalinity, and KMnO ₄ were measured at the rear of the settling tank, Al was measured at the rear of the settling tank and filtration, respectively, and the CO ₂ facility was operated with the pH set to 7.

enemy Example 9% sulfuric acid CO ₂ Facility S1 S3 appearance Al ₂ O ₃ (%) - One 3 - - Sulfate ion (%) - 21 21 - - Dosage (ppm) - 40 75 - coagulant - Aluminum polyhydrochloride sulfate Dosage (ppm) - 13ppm day 1 pH 8.51 7.07 7.08 7.07 7.06 Turbidity (NTU) 2.21 0.278 0.264 0.395 0.397 Alkalinity (mg/l) 18.2 13.7 13.8 13.9 13.8 KMnO ₄ (mg/l) 16.2 4.3 4.2 5.9 6.1 Al (mg/l) precipitation water 0.021 0.087 0.080 0.121 0.120 filtrate 0.031 0.042 0.078 0.073 day 2 pH 8.42 7.05 7.05 7.04 7.05 Turbidity (NTU) 2.27 0.281 0.261 0.412 0.408 Alkalinity (mg/l) 18.0 13.7 13.6 13.7 13.8 KMnO ₄ (mg/l) 16.3 4.2 4.1 6.0 5.9 Al (mg/l) precipitation water 0.027 0.083 0.089 0.119 0.119 filtrate 0.043 0.039 0.072 0.075 day 3 pH 8.39 7.05 7.06 7.07 7.04 Turbidity (NTU) 2.25 0.276 0.259 0.391 0.396 Alkalinity (mg/l) 17.9 13.6 13.7 13.6 13.6 KMnO ₄ (mg/l) 16.5 4.3 4.3 5.8 6.2 Al (mg/l) precipitation water 0.025 0.084 0.089 0.120 0.121 filtrate 0.037 0.039 0.073 0.069 Day 4 pH 8.45 7.02 7.03 7.05 7.04 Turbidity (NTU) 2.36 0.283 0.265 0.396 0.401 Alkalinity (mg/l) 18.1 13.7 13.6 13.5 13.7 KMnO ₄ (mg/l) 16.4 4.6 4.5 6.2 6.1 Al (mg/l) precipitation water 0.024 0.083 0.087 0.118 0.119 filtrate 0.039 0.040 0.080 0.075 coagulant properties Polyhydrochlorinated aluminum sulfate Al ₂ O ₃ 10.5%, Basicity 70.3%

As shown in Table 8, when the present invention is used in combination with polyhydrochloride aluminum sulfate, which is a conventional coagulant, it is confirmed that the reduction effect of residual aluminum, turbidity, KMnO ₄ , etc. is excellent, and the water treatment efficiency is high, and sulfuric acid It was confirmed that residual aluminum was reduced by about 40% compared to the case of using or CO ₂ facility.

<Experimental Example 7> Residual aluminum reduction effect when used in combination with a sulfuric acid-based coagulant further including an additive

After adding additives (group 2A, 3A, 4A, 3B, 4B materials) to the sulfuric acid-based coagulant prepared by the method of Example 1, water from the H water purification plant was collected and coagulated using a Jar-test. An experiment was conducted. The effect of reducing residual aluminum was confirmed by adding it in combination with polyhydroxychlorinated aluminum sulfate, and the properties of the raw water used in the flocculation experiment, the properties of the coagulant, the amount of coagulant, the type of additives, and the input results are shown in Table 12.

- 9% sulfuric acid Examples (+ additives) not added Group 2A Group 3A Group 4A Group 3B Group 4B Dosage (ppm) - 90 35 coagulant Aluminum polyhydrochloride sulfate Dosage (ppm) 13 pH 8.21 7.13 7.07 7.10 7.13 7.11 7.12 7.11 Turbidity (NTU) 0.427 0.390 0.231 0.225 0.228 0.224 0.226 0.223 Al (mg/l) 0.181 0.121 0.082 0.079 0.078 0.076 0.077 0.076 note 1) Raw water properties: pH 8.51, turbidity 3.18NTU, Al 0.028mg/l
2) Coagulant properties: Polyhydrochlorinated aluminum sulfate Al ₂ O ₃ 10.5%, Basicity 70.3%
3) Sulfuric acid-based coagulant properties: Al ₂ O ₃ 1.8% sulfate ion 23%
4) Additive properties
- Group 2A material: Add 0.5% by weight of CaCl ₂
- Group 3A material: Add 0.5% by weight of Ga ₂ (SO ₄ ) ₃
- Group 4A material: Add 0.5% by weight of Na ₂ SiO ₃
- Group 3B material: Add 0.5% by weight of YCl ₃ 6H ₂ O
- Group 4B material: Add 0.5% by weight of ZrCl ₄

As shown in Table 12, the level of residual aluminum was very high when the pH was not adjusted by combining with the existing coagulant, and compared to the case of adding 9% sulfuric acid in combination, the coagulant of the present invention was added in combination. In the case of turbidity, aluminum, etc., it was confirmed that the reduction effect was better. In addition, it was confirmed that the turbidity removal efficiency and the residual aluminum reduction effect were more excellent when the sulfuric acid-based coagulant was further included than when the additive was not included. In addition, it was confirmed that there was no significant change in water treatment efficiency even when the types of additives were different.

<Experimental Example 8> Residual aluminum reduction effect when used in combination with a sulfuric acid-based coagulant further including an additive

After adding additives (group 2A, group 3B material, polymer) to the sulfuric acid-based coagulant prepared by the method of Example 1, water from the H water purification plant was sampled and a coagulation experiment was conducted using a Jar-test. The effect of reducing residual aluminum was confirmed by adding it in combination with polyhydroxychlorinated aluminum sulfate.

- 9% sulfuric acid Examples (+ additives) not added Group 2A Group 3B Dosage (ppm) - 95 65 65 65 coagulant Polyhydrochloride Aluminum Sulphate Dosage (ppm) 13 coagulant Polymer Dosage (ppm) 3 pH 8.31 7.07 7.05 7.10 7.08 Turbidity (NTU) 0.387 0.361 0.178 0.163 0.165 Al (mg/l) 0.171 0.105 0.073 0.070 0.069 note 1) Raw water properties: pH 8.45, turbidity 3.33NTU, Al 0.031mg/l
2) Coagulant properties: Polyhydrochlorinated aluminum sulfate Al ₂ O ₃ 10.5%, Basicity 70%
3) Sulfuric acid-based coagulant properties: Al ₂ O ₃ 4% sulfate ion 16%
4) Additive properties
- Group 2A material: Add 0.5 parts by weight of CaCl ₂
- Group 3B material: Add 0.5% by weight of YCl ₃ 6H ₂ O
- Polymer: Polyamine

As shown in Table 13, the level of residual aluminum was very high when the pH was not adjusted by co-administration with the existing coagulant, and compared to the case of adding 9% sulfuric acid in combination, the coagulant of the present invention was added in combination In the case of turbidity, aluminum, etc., it was confirmed that the reduction effect was better. In addition, it was confirmed that the turbidity removal efficiency and the residual aluminum reduction effect were more excellent when the sulfuric acid-based coagulant was further included than when the additive was not included. In addition, it was confirmed that there was no significant change in water treatment efficiency even when the types of additives were different.

<Experimental Example 9> Residual aluminum reduction effect when used in combination with a sulfuric acid-based coagulant further containing an additive

After adding an additive (polyvinylamine as an organic coagulant) to the sulfuric acid-based coagulant prepared by the method of Example 1, water from the water purification plant I was sampled and a coagulation experiment was conducted using a Jar-test. The effect of reducing residual aluminum was confirmed by adding it in combination with polyaluminum chloride, and the properties of the raw water used in the coagulation experiment, the properties of the coagulant, the amount of coagulant, the mixing ratio of additives, and the input results are shown in Table 14.

9% sulfuric acid Example (+ Polymer mixing ratio) 0% 0.5% One% 3% 5% 7% Dosage (ppm) 70 30 30 30 30 30 30 coagulant polyaluminum chloride Dosage (ppm) 13 pH 7.11 7.03 7.05 7.07 7.11 7.15 7.21 Turbidity (NTU) 0.675 0.519 0.475 0.412 0.385 0.340 0.311 Al (mg/l) 0.111 0.093 0.091 0.085 0.082 0.082 0.096 note 1) Raw water properties: pH 8.45, turbidity 4.02NTU, Al 0.025mg/l
2) Coagulant properties: polyaluminum chloride Al ₂ O ₃ 10.5% Basicity 40%
3) Sulfuric acid-based coagulant properties: Al ₂ O ₃ 3.5% sulfate ion 23%
4) Additive properties: Polymer - Polyvinylamine

As shown in Table 14, it was confirmed that the effect of reducing turbidity, aluminum, etc. was more excellent when the coagulant of the present invention was used in combination compared to the case where the conventional coagulant and 9% sulfuric acid were added together. In addition, in the case of a product in which a polymer was mixed with a sulfuric acid-based coagulant, the turbidity removal efficiency was excellent as the mixing ratio of the polymer increased, but it was confirmed that the residual aluminum reduction effect was lowered when the mixture was mixed in excess of 7%.

<Experimental Example 10> Residual aluminum reduction effect when used in combination with a sulfuric acid-based coagulant further containing an additive

After adding additives (group 4A, group 4B material, polymer) to the sulfuric acid-based coagulant prepared by the method of Example 1, water from J water purification plant was sampled and a coagulation experiment was conducted using a Jar-test. It was added in combination with low-basic polyaluminum chloride to confirm the effect of reducing residual aluminum.

- 9% sulfuric acid Examples (+ additives) not added Group 4A Group 4B Dosage (ppm) - 170 70 70 70 coagulant Low-basic polyaluminum chloride Dosage (ppm) 15 pH 8.87 7.08 7.04 7.09 7.07 Turbidity (NTU) 0.856 0.832 0.541 0.529 0.531 Al (mg/l) 0.199 0.118 0.095 0.090 0.091 note 1) Raw water properties: pH 9.12, turbidity 3.20NTU, Al 0.021mg/l
2) Coagulant properties: Low-basic polyaluminum chloride Al ₂ O ₃ 11.5%, Basicity 15%
3) Sulfuric acid-based coagulant properties: Al ₂ O ₃ 4% sulfate ion 23%
4) Additive properties
- Group 4A material: Add 0.5 parts by weight of Na ₂ SiO ₃
- Group 4B material: Add 0.5% by weight of ZrCl ₄
- Polymer: 3 parts by weight of polyethyleneamine added

As shown in Table 15, the level of residual aluminum was very high when the pH was not adjusted by using the coagulant of the present invention in combination with the coagulant of the present invention, compared to the case of using 9% sulfuric acid in combination. In the case of turbidity, aluminum, etc., it was confirmed that the reduction effect was better. In addition, it was confirmed that when the additive was further included in the sulfuric acid-based coagulant, the turbidity removal efficiency and the residual aluminum reduction effect were more excellent than when the additive was not included. In addition, it was confirmed that there was no significant change in water treatment efficiency even when the types of additives were different.

<Experimental Example 10> Range of combined use of sulfuric acid-based coagulants

The sulfuric acid-based coagulant prepared by the method of Example 1 was collected from water from K water purification plant, and an aggregation experiment was conducted using a Jar-test. It was added in combination with polyhydroxychlorinated aluminum sulfate to confirm the effect of reducing residual aluminum.

- 9% sulfuric acid Example Dosage (ppm) - 220 12 25 40 75 100 coagulant Aluminum polyhydrochloride sulfate Dosage (ppm) 14 pH 9.26 7.11 9.07 8.62 8.13 7.58 7.09 Turbidity (NTU) 0.432 0.402 0.418 0.335 0.287 0.252 0.218 Al (mg/l) 0.202 0.118 0.179 0.145 0.128 0.093 0.087 note 1) Raw water properties: pH 9.45, turbidity 4.28NTU, Al 0.030mg/l
2) Coagulant properties: Polyhydrochlorinated aluminum sulfate Al ₂ O ₃ 10.5% Basicity 70%
3) Sulfuric acid-based coagulant properties: Al ₂ O ₃ 3% sulfate ion 28%,

As shown in Table 16, when the pH of the treated water was 7.0 to 8.0 after co-injection with the existing coagulant, it was confirmed that the turbidity and residual aluminum reduction effect was excellent.

Therefore, the method of reducing aluminum according to the water treatment of the coagulant according to the present invention has an excellent effect that aluminum is finally significantly reduced even though aluminum is further included. In particular, in the case of a water purification plant for obtaining water to be consumed by the human body, residual aluminum is managed at 0.2 mg/L or less to prevent Alzheimer's induction, and the present invention has excellent effects in that it is a method suitable for satisfying these conditions. there is.

Claims (8)

a) preparing a coagulant by mixing sulfuric acid, aluminum hydroxide and water;
a1) mixing 0.5 to 12% by weight of aluminum hydroxide (Al(OH) ₃ ) having an aluminum oxide concentration of 55 to 65% and 25 to 40% by weight of water relative to the total weight of the coagulant in a reactor;
a2) adding 10 to 35% by weight of sulfuric acid having a sulfuric acid concentration of 70 to 99% relative to the total weight of the coagulant and reacting at a temperature of 120 to 150 ° C. for 30 to 80 minutes;
a3) adding sulfuric acid and aluminum hydroxide to the reactant to adjust the pH and adding 30 to 45% by weight of water relative to the total weight of the coagulant to adjust the concentration; preparing a coagulant; and
b2) adding the coagulant of step a) in combination with the inorganic coagulant polyhydrochloride aluminum sulfate, wherein the coagulant of step a) includes aluminum oxide and sulfate ions,
The coagulant has a sulfate ion content of 10 to 30% by weight and an aluminum oxide content of 0.5 to 5% by weight,
A method for reducing aluminum by performing water treatment, wherein the residual aluminum is reduced to 5 to 90% compared to the case where the coagulant of step a) is not introduced, and the pH of the treated water is 8.5 or less.
According to claim 1,
The coagulant of step a) further comprises at least one compound selected from the group consisting of a group 2A compound, a group 3A compound, a group 4A compound, a group 3B compound, a group 4B compound, and salts thereof, by performing water treatment with aluminum how to reduce
According to claim 1,
The coagulant in step a) is one selected from the group consisting of Group 2A chloride, Group 2A sulfide, Group 3B chloride, Group 3B sulfide, Group 4B chloride, Group 4B sulfide, sodium silicate (Na ₂ SiO ₃ ), and salts thereof. A method for reducing aluminum by performing water treatment, further comprising the above compound.
delete delete According to claim 1,
The inorganic coagulant of step b2) has an aluminum oxide content of 5 to 25% relative to the total weight of the inorganic coagulant, a method for reducing aluminum by water treatment.
delete The method of claim 1, wherein the aluminum reduction method is a method for reducing aluminum by performing water treatment, characterized in that the turbidity of the treated water after treatment is 2 NTU or less.