KR101159236B1 - Method of preparation for low basicity polyaluminum chloride coagulant and treating method of water/wastewater using the same - Google Patents

Abstract

PURPOSE: A method for preparing polyaluminum chloride coagulants with low basicity and a water treating method using the same are provided to prevent the reduction of remaining aluminum and the occurrence of coloring phenomenon. CONSTITUTION: A first resultant product is generated by introducing aluminum hydroxide and hydrochloric acid. The first resultant product is polyaluminum chloride represented by chemical formula 1. The content of aluminum oxide in the polyaluminum chloride is in a range between 15 and 18%. The first resultant product is reacted with hydrochloric acid as a basicity adjusting agent to generate polyaluminum chloride with low basicity represented by chemical formula 2. The basicity of the polyaluminum chloride with low basicity is in a range between 10 and 20%. In chemical formula 1, n is between 1.5 and 5.5, inclusively; and m is 10 or less. In chemical formula 2, n is between 0.5 and 3, inclusively; and m is 10 or less.

Description

Method of Preparation for Low basicity polyaluminum chloride coagulant and Treating Method of water / wastewater using the same}

The present invention relates to a method for producing a flocculant for water purification and sewage and wastewater treatment, and more particularly, to a method for producing a polybasic aluminum chloride flocculant with a low base, and a method for treating water and sewage and wastewater using the same.

It is estimated that 25-30% of the total pollutant load by organic substances in the river water system is caused by algae. Phosphorus is the main cause of algae growth, and the pollution level of phosphorus causing algae is continuously increasing. Due to the decay of algae, the COD concentration, which is an indicator of hardly degradable organic substances, is also increasing, making it difficult to manage water quality of water supplies.

Accordingly, the possibility of algae generation is removed by removing phosphorus from the treated water of sewage and wastewater treatment facilities, and it is necessary to recover the ecosystem of urban streams that have been dried up by supplying agricultural water and supplying river maintenance water and to secure water in unsupply areas. It is true. In addition, as pollution sources change due to the use of chemicals in public waters, the formation of natural organic substances and the inflow of hardly degradable organic substances, new management indicators are required to change from BOD, which is the existing water quality management index, to total phosphorus and COD. In response to this, the Ministry of Environment has strengthened the discharged water quality standards for sewage treatment plants and wastewater treatment plants for total personnel and COD to preserve the public water ecosystem.

Phosphorus is relatively low in solubility, making it easy to form precipitates in water. Phosphorus is removed in the form of water absorbed by microorganisms in biological processes. In chemical processes, it is in the form of precipitates that are chemically or physically bound to flocculants. Removed. In order to effectively remove phosphorus from each sewage and wastewater treatment plant treatment, it is possible to treat phosphorus effectively with coagulation-precipitation or coagulation-filtration facilities, which are physical and chemical treatment processes, rather than biological treatment processes. In addition, the physical and chemical treatment process has a characteristic that can actively cope with the fluctuation of inflow water quality, so the Ministry of Environment improves the public water quality by installing a total phosphorus treatment facility for the management of phosphorus that acts as a limiting factor for algae growth in rivers and lakes. Various studies on chemical treatment of phosphorus using flocculant have been conducted to achieve this purpose.In addition, each sewage and wastewater treatment plant has a separate total phosphorus treatment facility for enhanced total phosphorus water quality standards or a flocculant is used in existing treatment facilities. To take measures.

Coagulants used for effective treatment of phosphorus are known as liquid aluminum sulfate (alum) containing a lot of monomeric Al (III) species or polyaluminum chloride (PAC) having a basicity of zero. However, for suspended particles in water, the basicity is known to have high aggregation efficiency in the case of polyaluminum chloride (PAC), and the basicity is used in the initial solution and the OH ^- ion added as a base in the preparation of polyaluminum chloride (PAC). of the Al ^{3 +} ion molar concentration ratio of the ^- denotes a _{(i.e., [OH added] / [Al} T]). As the basicity value increased from 0, polymeric Al (III) species (eg Al ₁₃ (OH) ₃₂ ⁷⁺ ) gradually increased, but precipitated Al (III) species (eg Al (OH) ₃ ) at specific upper limit values. Is formed. That is, the coagulation efficiency is different from each other depending on the degree of inclusion of Al (III) species in the coagulant. Therefore, it is necessary to select a flocculant with high flocculation efficiency for suspended solids or suspended particles in water as well as phosphorus in sewage water.

As a prior art related to a water treatment agent for removing phosphorus in sewage and wastewater treatment, for example, in Korea Patent Publication No. 10-1016392, a flocculant composition for water treatment containing zirconium in an aluminum inorganic coagulant and water treatment using the same Korean Patent Laid-Open Publication No. 2001-0094714 discloses a calcium artificial zeolite, a soluble aluminum-based or iron salt-based compound, a natural or synthetic polymer coagulant, an alkali metal carbonate granule, and a calcium compound and alkaline earth. Disclosed is a water treatment composition composed of two or more functional aids selected from the group consisting of metal carbonates, titanium dioxide and powdered activated carbon to remove nitrogen and phosphorus in sewage / wastewater simultaneously.

In addition, as a prior art related to the aluminum-based inorganic coagulant for water treatment, for example, Korean Patent Publication No. 1999-0049511 discloses a coagulant for treating high-polymerization aluminum chloride water containing Na, Ca or Mg, and registered in Korea. Patent Publication No. 10-0622295 discloses a method for preparing polyaluminum chloride having a basicity of 45% or more by adding a water diluent such as borax, sodium silicate, and zeolite in the process of producing polyaluminum chloride. -0730578 discloses a process for the production of highly basic (50-70%) polyaluminum chloride from sodium hydroxide [Na ₂ + Cl (OH)] and aluminum hydroxide, the Journal of Environmental Engineering, Vol. 32, No. 8 Arc, p. 774-779 describes the results of research carried out with a focus on the reaction between aluminum and phosphorus in water treatment.

In general, polyaluminum chloride (PAC) having an Al ₂ O ₃ content of 15 to 18% used in water treatment processes is more prone to polymerization of aluminum ions as it is manufactured with a higher base, and Schultz-hardy's law It is well known in the art that a high flocculation effect can be obtained even with a small dosage, and the basicity of polyaluminum chloride for water purification is defined as 30 to 60% due to its stability. When the excess amount of HCl) is generated, it is generated as a precipitate with the increase of the unreacted material has a problem that the stability of the product is unstable.

The present inventors have completed the present invention by developing a low base polyaluminum chloride (PACB) to improve the cohesive efficiency of not only phosphorus contained in water than the existing inorganic coagulant but also suspended matter or suspended particles. .

The present invention solves the problems of the prior art, and a method for producing a low-basicity polyaluminum chloride (PACB) flocculant for increasing the flocculation efficiency in water purification and sewage and wastewater treatment and a low-basicity polyaluminum chloride (PACB) flocculant It is an object of the present invention to provide a method for treating purified water and sewage and wastewater, and more specifically, to reduce the volume of sludge, to reduce residual aluminum and to prevent coloration during the treatment of drinking water. And a method for producing a low-basicity polyaluminum chloride chloride (PACB) flocculant which prevents eutrophication of green algae and the like by removing phosphorus and a method for treating water and sewage and wastewater using a low-basicity polyaluminum chloride (PACB) flocculant. will be.

As a solution of the method for producing a polybasic aluminum chloride flocculant, which is the object of the present invention, (a) aluminum hydroxide (Al (OH) ₃ ) and hydrochloric acid (HCl) are added to a temperature of 120 to 170 ° C. Reacting for 10 hours to produce a primary reactant, which is polyaluminum chloride (PAC) having an Al ₂ O ₃ content of 15 to 18% represented by the following formula (1), (b) a primary reactant and a base It is characterized in that the polybasic hydrochloride (PACB), which is represented by the following formula (2) consisting of reacting hydrochloric acid (HCl) as a regulator, is prepared.

Formula (1): [Al ₂ (OH) _n Cl _6-n ] _m (where 1.5 ≦ _n ≦ 5.5, _m ≦ 10)

Formula (2): [Al ₂ (OH) _n Cl _6-n ] _m (where 0.5 ≦ _n ≦ 3, _m ≦ 10)

The primary reactant generation step according to the present invention is 120 to 170 by adding 1 mol of aluminum hydroxide [Al (OH) ₃ , Al (OH) ₃ or more 99.0%] and hydrochloric acid (HCl, 30-35%). After reacting at a temperature of 5 to 10 hours, water was added to 10 to 20 wt% with respect to the reactants, and the basicity was 35 to 45%, and the Al ₂ O ₃ content was adjusted to 15 to 18% polyaluminum chloride ( PAC) to prepare a primary reactant represented by the formula (1).

The primary reactant, polybasic aluminum chloride (PAC) having a basicity of 35 to 45% and an Al ₂ O ₃ content of 15 to 18% has excellent cohesive performance, but precipitates a solid phase during a long storage period. It is known that the stability of is low.

In the present invention, 10 to 20 parts by weight of hydrochloric acid (HCl, 30 to 35%) and 5 to 40 parts by weight of water are added to 100 parts by weight of the first reactant as a base regulator and reacted at a temperature of 40 to 80 ° C. for 1 to 5 hours. It is made of a polybasic aluminum chloride (PACB) low salt represented by the formula (2) having a basicity of 10 to 20%, Al ₂ O ₃ content of 8 to 15%.

The low-basicity polyaluminum chloride (PACB) having [Al ₂ (OH) _n Cl _6-n ] _m (wherein 0.5 ≦ _n ≦ 3, _m ≦ 10) represented by Chemical Formula (2) prepared in the present invention has excellent aggregation Performance is maintained and shows good stability, such as no precipitation of solid phase over long periods of storage.

Low basicity polyaluminum chloride (PACB) represented by the formula (2) having a basicity of 10 to 20% and Al ₂ O ₃ content of 8 to 15% prepared according to the preparation method of the present invention has excellent aggregation. Performance is maintained and shows good stability, such as no precipitation of solid phase over long periods of storage.

Low basicity polyaluminum chloride (PACB) represented by the formula (2) having a basicity of 10 to 20% and Al ₂ O ₃ content of 8 to 15% prepared according to the preparation method of the present invention has excellent aggregation. Performance is maintained and shows good stability, such as no precipitation of solid phase over long periods of storage.

In addition, it reduces the volume of sludge generated in drinking water and wastewater treatment, prevents the reduction of residual aluminum and coloring, and shows cohesive ability even in high turbidity and removes algae. In particular, it has an excellent effect of removing organic substances and phosphorus and has excellent flocculant properties to prevent eutrophication of green algae and the like.

1 is a graph illustrating the results of the flocculation efficiency with respect to the flocculant injection amount in <Test Example 4> of the present invention.
2 and 3 are graphs illustrating the results of the flocculation efficiency with respect to the coagulant injection amount in <Test Example 5> of the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples do not limit the present invention.

&Lt; Example 1 >

(a) a primary reactant; Preparation of Formula (1)

At least 99.0% of aluminum hydroxide [Al (OH) ₃ , Al (OH) ₃ ] 900 kg and 1,800 kg of hydrochloric acid (HCl, 34.5%) were added and reacted at a temperature of 140 ° C. for 7 hours. 3,000 kg of polyaluminum chloride (PAC) having a basicity of 40% and an Al ₂ O ₃ content of 17% was prepared.

(b) Preparation of Formula (2)

520 kg of hydrochloric acid (HCl, 34.5%) was added to 3,000 kg of the first reactant prepared above as a basicity regulator and reacted for 3 hours at a temperature of 55 ° C., diluted with water to give a basicity of 13.6% and an Al ₂ O ₃ content of 9.0. % of a low-salt airway poly aluminum chloride (PACB) 5,190kg was prepared ( "sample 1", hereinafter defined as 'PACB-01'). the chemical composition formula is _{[Al 2 (OH) 0.82 Cl} 5 .18].

&Lt; Example 2 >

(a) a primary reactant; Preparation of Formula (1)

900 kg of aluminum hydroxide [Al (OH) ₃ , Al (OH) ₃ and above 99.0%] 1,800 kg of hydrochloric acid (HCl, 34.5%) was added thereto, reacted at a temperature of 140 ° C. for 7 hours, and diluted with water to react with the primary reactant. 3,000 kg of polyaluminum chloride (PAC) having a phosphorus basicity of 40% and an Al ₂ O ₃ content of 17% was prepared.

(b) Preparation of Formula (2)

520 kg of hydrochloric acid (HCl, 34.5%) was added to 3,000 kg of the primary reactant prepared above as a basicity regulator, followed by reaction at a temperature of 55 ° C. for 3 hours, followed by dilution of water with a basicity of 13.6% and an Al ₂ O ₃ content. 4,130 kg of polybasic aluminum chloride (PACB) having a low basicity of 10.7% was prepared (defined as 'Sample 2', hereinafter 'PACB-02'). A chemical composition formula is _{(Al 2 (OH) 0.82 Cl} 5 .18).

&Lt; Example 3 >

(a) a primary reactant; Preparation of Formula (1)

900 kg of aluminum hydroxide (Al (OH) ₃ , Al (OH) ₃ and above 99.0%) and 1,800 kg of hydrochloric acid (HCl, 34.5%) were added and reacted at a temperature of 140 ° C. for 7 hours, followed by dilution with water. 3,000 kg of polyaluminum chloride (PAC) having a phosphorus basicity of 40% and an Al ₂ O ₃ content of 17% was prepared.

(b) Preparation of Formula (2)

520 kg of hydrochloric acid (HCl, 34.5%) was added to 3,000 kg of the first reactant prepared above as a basicity regulator, and the reaction was carried out at a temperature of 55 ° C. for 3 hours, diluted with water to give a basicity of 13.6%, and an Al ₂ O ₃ content of 3,600 kg of polybasic aluminum chloride (PACB) having a low basicity of 13.0% was prepared ('Sample 3', hereafter defined as 'PACB-03'). The chemical formula is (Al ₂ (OH) _0.82 Cl _{5 .18} ).

Comparative Example

900 kg of aluminum hydroxide (Al (OH) ₃ , Al (OH) ₃ and above 99.0%) and 2,320 kg of hydrochloric acid (HCl, 34.5%) were added thereto, reacted at a temperature of 140 ° C. for 7 hours, diluted with water, and the basicity was 17.8. 3,500 kg of low-basicity polyaluminum chloride (PACB) having a% and Al ₂ O ₃ content of 11.2% was prepared.

The <Comparative Example> is an excess of basicity for the comparison of the stability of the low basicity polyaluminum chloride (PACB) prepared by adding hydrochloric acid in two steps in <Example 1> to <Example 3> according to the present invention Hydrochloric acid (HCl, 34.5%) as a regulator was added to react in one step to prepare 3,500 kg of low-basic polyaluminum chloride (PACB), and the amount of hydrochloric acid (HCl, 34.5%) as a basicity regulator was 2,320 kg. In the embodiment of the invention is equal to the total amount of hydrochloric acid divided into two steps.

&Lt; Test Example 1 >

In order to compare the stability of the low-basicity polyaluminum chloride prepared in <Example 1> to <Example 3> and <Comparative Example>, the freezing of low-basicity polyaluminum chloride with long-term storage for 4 months at -20 ° C , The result of the stability of the product by measuring the occurrence of sediment, status and freezing are shown in [Table 1] below.

&Lt; Test Example 2 &

The occurrence and state of precipitates of low-basicity polyaluminum chloride according to long-term storage of the low-basicity polyaluminum chloride prepared in <Example 1> to <Example 3> and <Comparative Example> for 4 months at room temperature 20 ℃ It is shown in the following [Table 2] for the results of the stability of the product.

<Test Example 3>

The occurrence and state of precipitates of low-basicity polyaluminum chloride according to long-term storage of the low-basicity polyaluminum chloride prepared in <Example 1> to <Comparative Example 3> and <Comparative Example> for 4 months at a high temperature of 50 ℃ The results for the stability of the product by measuring the [Table 3] is shown below.

<Test Example 4>

In order to examine the water treatment coagulation characteristics of the polybasic aluminum chloride (PACB) (Samples 1, 2, 3) of the present invention, the Nakdong River (see the water quality conditions in Table 4 below) was collected by Jar-test Agglomeration experiments were used. Jar-tester (Phipps & Bird) used as a coagulation tester is equipped with six stirring devices. The size of the paddle (two-blade) connected to the stirring device is 2.54 ^W × 7.6 ^L cm, and the stirring speed can be adjusted. Device. In addition, Jar used in the flocculation experiment used a square of 2 L capacity.

Advantages of using rectangular jars include: ① reduction of vortex due to agitation; and ② sampling holes fixed at 10cm below the water surface, making it easy to calculate floc sedimentation rate. ③ Jar is a thick acrylic material, which means that the temperature change is small due to low heat transfer.

Agitation conditions of coagulation were determined through preliminary experiments using the average speed gradient (G) value according to the stirring speed (rpm). Each was ^{250rpm (G = 550sec -1 at 20} ℃) and ^{30rpm (G = 22 sec -1 at} 20 ℃) in the stirring conditions of the preliminary test results derived optimal value G and the stirring time is rapid and slow stirring time were 1min and 30min appeared, and the coagulation experiment was carried out under the derived stirring conditions and stirring time. At this time, the Gt values in the rapid mixing and the slow mixing were 33,000 and 39,600, respectively, and were within the ranges of the rapid mixing standard (24,000 ~ 84,000) of AWWA (1998). After slow stirring, the settling time was 30 minutes. After precipitation, the supernatant was collected at 10 cm below the surface of the water and analyzed for water quality.

TOC was measured to quantify the concentration of organics in water, and UV-254 is widely used to indirectly measure the state of change of organic matter (Ezdwald et al., 1985). Water quality analysis in the flocculation experiment was carried out by Standard methods (AWWA, 2005), the analysis method and the instrument used for water quality analysis is shown in Table 5 below.

The flocculant used in the flocculation experiment was 11.0 in the low base polyaluminum chloride (PACB) (samples 1, 2, 3) according to the present invention, and the Al ₂ O ₃ content, which is commonly used in water treatment and sewage and wastewater treatment, was 11.0. The flocculation efficiency of the coagulant according to the injection amount of the flocculant was investigated by using polyaluminum chloride (PAC, which is defined as 'PAC (1)' and 'PAC (3)'). It is shown in [Table 6] below.

<Agglomeration Experiment Result According to Coagulant Injection>       Flocculant   Injection amount ( mg / L)      Turbidity ( NTU ) UV ₂₅₄ ( cm ^-One ) DOC ( mg / L)


PACB -01
    (Sample 1)        0        9.58        0.073        1.789       10        9.81        0.042        1.679       15        4.67        0.040        1.378       20        2.03        0.035        1.336       30        0.706        0.033        1.321       40        0.397        0.031        1.318       60        0.550        0.027        1.192       80        0.808        0.024        1.181


PACB -02
    (Sample 2)        0        9.58        0.073        1.789       10        6.41        0.039        1.751       15        2.40        0.038        1.364       20        1.38        0.036        1.329       30        0.506        0.032        1.222       40        0.483        0.029        1.211       60        0.571        0.026        1.140       80        0.559        0.023        1.018


PACB -03
    (Sample 3)        0        9.58        0.073        1.789       10        3.64        0.038        1.550       15        1.12        0.036        1.362       20        0.666        0.033        1.320       30        0.616        0.030        1.220       40        0.506        0.028        1.150       60        0.621        0.025        1.087       80        0.545        0.024        0.994


Poly Aluminum Chloride       ( PAC (One))        0        9.58        0.073        1.789       10        7.45        0.043        1.457       15        1.47        0.036        1.430       20        0.895        0.036        1.398       30        0.473        0.032        1.320       40        0.518        0.030        1.236       60        1.060        0.027        1.261       80        0.963        0.026        1.052


Poly Aluminum Chloride       ( PAC (3))        0        9.58        0.073        1.789       10        9.32        0.040        1.552       15        1.59        0.034        1.531       20        0.538        0.029        1.414       30        0.594        0.026        1.248       40        1.020        0.024        1.072       60        0.994        0.022        1.044       80        0.816        0.021        0.842

As shown in the coagulation efficiency according to the coagulant injection amount of each coagulant used in the coagulation experiment of [Table 6], in the case of the low-basic polyaluminum chloride (PACB) (samples 1, 2, 3) according to the present invention, PAC ( Despite the lower Al ₂ O ₃ content compared to 1) and PAC (2), it shows similar or better flocculation efficiency, and especially shows excellent effect on the removal of organic matter in water (Fig. 1 to Fig. 3). Table 6 shows the results of the coagulation efficiency of the coagulant injection amount.

&Lt; Test Example 5 >

In order to examine the cohesive properties of low-altitude polyaluminum chloride (PACB) (samples 1, 2, 3), the sewage effluent is treated by biological treatment of sewage treatment plant before it enters the disinfection tank (see Water Quality Conditions [Table 7]). The coagulation test was performed using Jar-test, and the coagulation test apparatus was used in the 'coagulation characteristics of water treatment of low-basic polyaluminum chloride (PACB) (samples 1, 2, 3)' of [Test Example 4]. -tester (Phipps & Bird) was used and the same conditions were used.

In addition, water quality analysis in coagulation experiments was carried out by COD, turbidity, TP and PO ₄ -P, and the analysis method was performed by standard methods (AWWA, 2005) and water pollution process test method (Ministry of Environment). Analytical methods and instruments used for water quality analysis are shown in [Table 8].

In addition, the flocculant used in the flocculation experiment has a low basic polyaluminum chloride (PACB) (samples 1, 2, 3) according to the present invention, and Al ₂ O ₃ content which is commonly used in water treatment and sewage and wastewater treatment sites is 11.0. Using the polyaluminum chloride (PAC, hereinafter defined as 'PAC (1)' and 'PAC (3)') of 17% and 17%, the flocculation efficiency, which is the coagulation property of each flocculant, was investigated. Is shown in Table 9 below.

<Agglomeration Experiment Result According to Coagulant Injection>   Flocculant  Injection amount ( mg / L) COD ( mg / L) UV ₂₅₄ ( cm ^-One )    Turbidity ( NTU ) TP ( mg / L) PO ₄ -P ( mg / L)

PACB -01
 (Sample 1)        0     10.74      0.095      1.85      1.40     1.12       10     10.70      0.083      1.51      1.00     0.82       30     10.57      0.077      0.681      0.40     0.27       50     10.50      0.075      0.597      0.08     0.05      100      9.94      0.065      0.508      0.02     0.01      125      9.80      0.062      0.54      0.01     0.00      150      9.52      0.062      0.601      0.00     0.00

PACB -02
 (Sample 2)        0     10.74      0.095      1.85      1.40     1.12       10     10.49      0.082      1.55      0.85     0.64       30     10.18      0.075      0.531      0.25     0.10       50      9.81      0.073      0.390      0.06     0.03      100      9.60      0.063      0.596      0.03     0.01      125      9.48      0.060      0.647      0.02     0.00      150      9.38      0.059      0.564      0.02     0.00

PACB -03
 (Sample 3)        0     10.74      0.095      1.85      1.40     1.12       10     10.42      0.081      1.49      0.85     0.64       30      9.96      0.075      0.571      0.20     0.18       50      9.56      0.070      0.491      0.06     0.02      100      9.42      0.061      0.655      0.04     0.01      125      9.27      0.059      0.684      0.03     0.00      150      9.19      0.058      0.567      0.03     0.00

Polychlorinated
 aluminum
 ( PAC (One))        0     10.74      0.095      1.85      1.40     1.12       10     10.55      0.083      2.05      1.20     0.92       30     10.49      0.080      0.813      0.60     0.36       50     10.35      0.074      0.614      0.18     0.11      100     10.32      0.065      0.886      0.09     0.04      125     10.22      0.065      0.823      0.09     0.04      150     10.07      0.064      1.08      0.07     0.04

Polychlorinated
 aluminum
 ( PAC (3))        0     10.74      0.095      1.85      1.40     1.12       10     10.50      0.081      1.51      0.90     0.68       30     10.33      0.076      0.571      0.25     0.16       50     10.14      0.070      0.604      0.06     0.03      100      9.51      0.062      0.803      0.05     0.02      125      9.53      0.060      0.909      0.04     0.01      150      9.42      0.059      0.917      0.03     0.01

As shown in the coagulation efficiency according to the coagulant injection amount of each coagulant used in the coagulation experiment of [Table 9], in the case of the low-basic polyaluminum chloride (PACB) (samples 1, 2, 3) according to the present invention, PAC ( 1) and Although the Al ₂ O ₃ content is lower than that of PAC (3), it exhibits excellent flocculation efficiency, and particularly shows excellent effects on the removal of organic matter and the removal of phosphorus and phosphate phosphorus in water (Fig. 2). Shows the results of the coagulation efficiency of the coagulant injection amount of [Table 9].

Claims (9)

(a) by adding aluminum hydroxide (Al (OH) ₃ ) and hydrochloric acid (HCl) to react the polyaluminum chloride (PAC) is adjusted to 15 ~ 18% Al ₂ O ₃ content represented by the formula (1) Producing a first reactant,
(b) reacting hydrochloric acid (HCl) with a primary reactant and a basicity regulator to produce a low base polyaluminum chloride (PACB) having a basicity of 10 to 20% represented by the following formula (2): A method for producing a low base polyaluminum chloride (PACB) flocculant.
Formula (1)
[Al ₂ (OH) _n Cl _6-n ] _m (where 1.5 ≦ _n ≦ 5.5, _m ≦ 10)
Formula (2)
[Al ₂ (OH) _n Cl _6-n ] _m (0.5 ≦ _n ≦ 3, _m ≦ 10) The method of claim 1, wherein the aluminum hydroxide (Al (OH) ₃ ) and hydrochloric acid (HCl) is reacted for 5 to 10 hours at a temperature of 120 ~ 170 ℃ in the step of producing a primary reactant of step (a), (b) A method for producing a low basic polyaluminum chloride (PACB) flocculant, characterized in that hydrochloric acid (HCl) is reacted at a temperature of 40 to 80 ° C. for 1 to 5 hours with the primary reactant of the step and a basicity regulator. The method of claim 1 or 2, wherein the general formula (2) has a basicity of 13.6% and an Al ₂ O ₃ content of 9.0%. The method of producing a polybasic aluminum chloride (PACB) flocculant of claim 1 or 2, wherein the formula (2) has a basicity of 13.6% and an Al ₂ O ₃ content of 10.7%. The method of claim 1 or 2, wherein the formula (2) has a basicity of 17.8% and an Al ₂ O ₃ content of 11.2%.  Purified or sewage / wastewater characterized by treating a purified water or sewage / water with a low basic degree polybasic polychloride (PACB) flocculant having a basicity of 10 to 20% represented by formula (2) according to claim 1 or 2. Treatment method. The method for treating purified water or sewage and wastewater according to claim 6, wherein the general formula (2) is a polybasic aluminum chloride (PACB) coagulant having a basicity of 13.6% and an Al ₂ O ₃ content of 9.0%. The method for treating purified water or sewage / wastewater according to claim 6, wherein the general formula (2) is a polybasic aluminum chloride (PACB) flocculant having a basicity of 13.6% and an Al ₂ O ₃ content of 10.7%. The method for treating purified water or sewage or wastewater according to claim 6, wherein the general formula (2) is a polybasic aluminum chloride (PACB) flocculant having a basicity of 17.8% and an Al ₂ O ₃ content of 11.2%.

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