Composition for removing calcium and magnesium ions in wastewater and use method thereof

Abstract

The invention discloses a composition for removing calcium and magnesium ions in wastewater and a using method thereof.The composition comprises a complexing agent and a flocculating agent, and the complexing agent comprises, by mass, 20-40% of sodium dihydrogen phosphate, 50-70% of sodium carbonate and 5-10% of calcium hydroxide; the flocculating agent is a polysilicate aluminum flocculating agent; and the flocculant accounts for 0.2-0.4% of the mass of the complexing agent. According to the composition, carbonate ions, phosphate ions and hydroxyl ions are introduced to remove calcium and magnesium ions in wastewater, meanwhile, the flocculating agent is added for compounding use, the used agents are low in price and wide in source, operation is easy and convenient, and the treatment effect is good.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and more particularly to a composition for removing calcium and magnesium ions in wastewater and a method for using the composition. Background Art

[0002] In industrial production, the circulation of high-calcium water will make calcium and magnesium ions easily react with carbonate, sulfate, etc. to form insoluble calcium and magnesium precipitates (such as scale), which will be deposited on the surface of boilers, cooling towers, pipelines and other equipment, resulting in reduced equipment efficiency and increased energy consumption. Scaling will lead to reduced heat exchange efficiency, which in turn will cause equipment overheating, deformation or even damage. In severe cases, it may cause equipment failure or explosion. High concentrations of calcium and magnesium ions in wastewater may affect the performance of reverse osmosis membranes during the treatment process, causing clogging of membrane pores and reducing the separation efficiency of the membrane, thereby affecting the quality of production water and treatment effects. Due to scaling and equipment damage, the frequency of cleaning and maintenance needs to be increased, which increases the overall cost of production and operation.

[0003] In view of the above problems, the use of appropriate water treatment technology (such as softening, ion exchange, etc.) or improved process flow can effectively reduce the concentration of calcium and magnesium ions in wastewater, thereby reducing its impact on equipment and the environment. At present, the methods for controlling water hardness mainly include traditional pH adjustment method, chemical descaling agent method and ion exchange softening method. Chemical precipitation method is an effective water treatment technology that can quickly remove calcium ions from water and is widely used in the treatment of industrial wastewater. The basic principle of this method is to add chemical precipitants (such as lime water, phosphates or other reagents) to make calcium ions react with precipitants to form insoluble precipitates, thereby achieving removal. The chemical precipitation reaction occurs quickly and can effectively reduce the calcium ion concentration in water in a short time, which is suitable for occasions that require rapid treatment. The process flow of this method is relatively simple, and usually only precipitants need to be added during the treatment process, which reduces the dependence on complex equipment and reduces the difficulty of operation. The operation and maintenance of chemical precipitation equipment are relatively simple, which is convenient for large-scale application in industrial sites and suitable for wastewater treatment of different scales. Summary of the invention

[0004] In view of this, the present application provides a composition and a method of use that are simple to operate and have significant effects on removing wastewater with high concentrations of calcium and magnesium ions. The residual content of calcium and magnesium ions in the wastewater treated by this method is significantly reduced, and the descaling effect is good and the descaling efficiency is high.

[0005] In the first aspect, in order to achieve the above-mentioned purpose, the present application provides a composition for removing calcium and magnesium ions in wastewater, adopting the following technical scheme:

[0006] A composition for removing calcium and magnesium ions in wastewater, comprising a composite agent and a flocculant, wherein the composite agent comprises the following components by mass percentage:

[0007] Sodium dihydrogen phosphate 20-40%, sodium carbonate 50-70%, calcium hydroxide 5-10%;

[0008] The flocculant is a polyaluminium silicate flocculant;

[0009] The flocculant accounts for 0.2-0.4% of the mass of the composite agent.

[0010] By adopting the above technical scheme, the composition in the present application is not only easy to dissolve in water, but also does not scale in water. In addition, sodium dihydrogen phosphate, sodium carbonate and calcium hydroxide will generate phosphate ions, carbonate ions and hydroxide ions in water, and the synergistic effect between these three ions prompts them to react with calcium ions and magnesium ions to form precipitation. At the same time, the formed precipitate will promote the aggregation of precipitates through the polymerization and flocculation of polysilicate aluminum, and significantly improve the density of the precipitate. This process not only accelerates the sedimentation rate of the precipitate, reduces the volume ratio of the precipitate, but also effectively improves the precipitation rate and stability of calcium and magnesium ions in wastewater. In addition, due to the effect of polysilicate aluminum, the precipitate is more stable, reducing the risk of resuspension, thereby improving the use effect of the water purifier and optimizing the overall efficiency of wastewater treatment. Through this comprehensive effect, more efficient water quality improvement can be achieved, and the performance and economy of the water purification system can be improved.

[0011] At the same time, the polyaluminum silicate aqueous solution cannot be directly mixed with the other three raw materials. It plays a role of polymerization and flocculation in the sediment flocculation process. Its dosage is small. Pre-configuring the polyaluminum silicate into an aqueous solution to obtain a polyaluminum silicate aqueous solution facilitates the control and addition of the polyaluminum silicate solution and improves the practicability of the flocculant.

[0012] Furthermore, the composite agent comprises the following components in percentage by mass:

[0013] Sodium dihydrogen phosphate 25%, sodium carbonate 65%, calcium hydroxide 10%;

[0014] The flocculant accounts for 0.3% of the mass of the composite agent.

[0015] By adopting the above technical solution, the ratio of each raw material is further optimized and the use effect of the composition is improved.

[0016] Furthermore, the polyaluminum silicate flocculant is prepared by the following method: adding polyaluminum silicate powder into water and mixing evenly to obtain the polyaluminum silicate flocculant, wherein the mass ratio of the polyaluminum silicate powder to water is 1:10.

[0017] By adopting the above technical solution, the composite agent has the advantages of easy preparation, low cost and simple process.

[0018] In a second aspect, in order to achieve the above-mentioned purpose, the present application provides a method for using a composition for removing calcium and magnesium ions in wastewater, using the following technical solution:

[0019] A method for using a composition for removing calcium and magnesium ions from wastewater comprises the following steps:

[0020] (1) firstly, disodium hydrogen phosphate, sodium carbonate and calcium hydroxide are mixed uniformly to obtain a composite agent;

[0021] (2) Add a compounding agent to the wastewater, stir and react for 2-10 minutes, then add a flocculant, continue stirring, react for 10-20 minutes, then let it stand for 10-20 minutes to form a precipitate and a supernatant, and remove the precipitate to complete the removal of calcium and magnesium ions in the wastewater.

[0022] By adopting the above technical solution, a composite agent is added to the wastewater to make phosphate ions, carbonate ions and hydroxide ions react with calcium ions and magnesium ions to form a precipitate. Then, a polysilicate aluminum flocculant is added to accelerate the precipitation of the precipitate through the synergistic effect between the precipitate and polysilicate aluminum, effectively improving the precipitation rate and stability of calcium and magnesium ions in the wastewater. In addition, the method of use of the present application is fast, simple and reliable, which can further improve the treatment effect, reduce the operating costs of the enterprise, and ensure environmental safety.

[0023] Furthermore, the concentration of calcium ions in the wastewater is ≤500 PPM, the concentration of magnesium ions in the wastewater is ≤300 PPM, and the amount of the composite agent used in the wastewater is 1-2 g / L.

[0024] By adopting the above technical solution, the calcium ion concentration, magnesium ion concentration and the amount of the composite agent used in the wastewater are limited, thereby improving the use effect of the composition.

[0025] It can be seen from the above technical solutions that, compared with the prior art, the present invention has the following technical effects:

[0026] 1. By adopting the above technical solutions, the composition in the present application adopts a series of advanced technical solutions, which has the advantages of being easy to dissolve in water and not easy to scale. By using sodium phosphate, sodium carbonate and calcium hydroxide, these ingredients can generate phosphate ions, carbonate ions and hydroxide ions in water. The synergistic effect between these three ions promotes the precipitation formation of calcium ions and magnesium ions.

[0027] 2. The generated precipitate, through the polymerization and flocculation of polysilicate aluminum, not only effectively promotes the aggregation of precipitate, improves the density of precipitate, but also accelerates the sedimentation rate of precipitate and reduces its volume. This series of effects effectively improves the precipitation rate and stability of calcium and magnesium ions in wastewater, while reducing the risk of resuspension of precipitate, thereby improving the use effect of the composite agent and the efficiency of wastewater treatment, achieving more efficient water quality improvement and optimizing the performance and economy of the water treatment system.

[0028] 3. The specific method of use is to add the compounding agent to the wastewater for stirring, and then add the flocculant for flocculation and precipitation. Through the synergistic effect of the compounding agent and the flocculant, the precipitation rate and stability of calcium and magnesium ions in the wastewater can be effectively improved, and it has the advantages of simple operation and stable treatment. This method ensures a high removal rate of calcium and magnesium ions in wastewater treatment, while reducing treatment costs. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Preparation Example

[0031] Preparation Example 1

[0032] A composition for removing calcium and magnesium ions in wastewater comprises a complexing agent and a flocculant.

[0033] In terms of mass percentage, the composite agent includes the following components: 40% sodium dihydrogen phosphate, 55% sodium carbonate, and 5% calcium hydroxide; the flocculant is polysilicate aluminum flocculant, which accounts for 0.2% of the mass of the composite agent.

[0034] Moreover, the composite agent is prepared by the following method: sodium dihydrogen phosphate, sodium carbonate and calcium hydroxide are uniformly mixed to obtain the composite agent.

[0035] The flocculant is prepared by the following method: adding aluminum polysilicate powder into water and mixing evenly to obtain the flocculant.

[0036] Preparation Example 2

[0037] A composition for removing calcium and magnesium ions in wastewater comprises a complexing agent and a flocculant.

[0038] In terms of mass percentage, the composite agent includes the following components: 35% sodium dihydrogen phosphate, 55% sodium carbonate, 10% calcium hydroxide, and the flocculant is polysilicate aluminum flocculant, which accounts for 0.2% of the mass of the composite agent.

[0039] Moreover, the composite agent is prepared by the following method: sodium dihydrogen phosphate, sodium carbonate and calcium hydroxide are uniformly mixed to obtain the composite agent.

[0040] The flocculant is prepared by the following method: adding aluminum polysilicate powder into water and mixing evenly to obtain the flocculant.

[0041] Preparation Example 3

[0042] A composition for removing calcium and magnesium ions in wastewater comprises a complexing agent and a flocculant.

[0043] In terms of mass percentage, the composite agent includes the following components: 30% sodium dihydrogen phosphate, 60% sodium carbonate, 10% calcium hydroxide, and the flocculant is polysilicate aluminum flocculant, which accounts for 0.3% of the mass of the composite agent.

[0044] Moreover, the composite agent is prepared by the following method: sodium dihydrogen phosphate, sodium carbonate and calcium hydroxide are uniformly mixed to obtain the composite agent.

[0045] The flocculant is prepared by the following method: adding aluminum polysilicate powder into water and mixing evenly to obtain the flocculant.

[0046] Preparation Example 4

[0047] A composition for removing calcium and magnesium ions in wastewater comprises a complexing agent and a flocculant.

[0048] In terms of mass percentage, the composite agent includes the following components: 25% sodium phosphate, 65% sodium carbonate, 10% calcium hydroxide, and the flocculant is polysilicate aluminum flocculant, which accounts for 0.3% of the mass of the composite agent.

[0049] Moreover, the composite agent is prepared by the following method: sodium dihydrogen phosphate, sodium carbonate and calcium hydroxide are uniformly mixed to obtain the composite agent.

[0050] The flocculant is prepared by the following method: adding aluminum polysilicate powder into water and mixing evenly to obtain the flocculant.

[0051] Example

[0052] Example 1

[0053] A method for using a composition for removing calcium and magnesium ions in wastewater, wherein the composite agent is obtained by the method of Preparation Example 1. The method for using the composition comprises the following steps:

[0054] Add calcium chloride and magnesium chloride to water, stir and mix evenly to obtain waste water for later use.

[0055] Moreover, the concentration of calcium ions in the wastewater is 500 PPM, and the concentration of magnesium ions in the wastewater is 300 PPM.

[0056] Take 1000mL of wastewater, add 1g of the composite agent, and stir. The composite agent reacts with the calcium ions and magnesium ions in the wastewater for 4 minutes. Then add the flocculant, continue stirring, react for 10 minutes, and then let it stand for 15 minutes to form a precipitate and a supernatant. Remove the precipitate to complete the removal of calcium and magnesium ions in the wastewater.

[0057] Example 2

[0058] A method for using a composition for removing calcium and magnesium ions in wastewater, which differs from Example 1 in that the composite agent is obtained using Preparation Example 2.

[0059] Example 3

[0060] A method for using a composition for removing calcium and magnesium ions in wastewater, which differs from Example 1 in that the composite agent is obtained using Preparation Example 3.

[0061] Example 4

[0062] A method for using a composition for removing calcium and magnesium ions in wastewater, which differs from Example 1 in that the composite agent is obtained using Preparation Example 4.

[0063] Example 5

[0064] A method for using a composition for removing calcium and magnesium ions in wastewater, which differs from Example 4 in that the method for using the composition comprises the following steps:

[0065] Add calcium chloride and magnesium chloride to water, stir and mix evenly to obtain waste water for later use.

[0066] Moreover, the concentration of calcium ions in the wastewater is 500 PPM, and the concentration of magnesium ions in the wastewater is 300 PPM.

[0067] Take 1000mL of wastewater, add 2g of the composite agent, stir, and the composite agent reacts with the calcium ions and magnesium ions in the wastewater for 4 minutes, then add the flocculant, continue stirring, react for 10 minutes, and then stand for 15 minutes to form a precipitate and a supernatant, and remove the precipitate to complete the treatment of calcium and magnesium ions in the wastewater.

[0068] Comparative Example

[0069] Comparative Example 1

[0070] A composition for removing calcium and magnesium ions in wastewater, which differs from Example 5 in that sodium dihydrogen phosphate is not added to the raw materials of the composite agent.

[0071] Comparative Example 2

[0072] A composition for removing calcium and magnesium ions in wastewater, which differs from Example 5 in that sodium carbonate is not added to the raw materials of the composite agent.

[0073] Comparative Example 3

[0074] A composition for removing calcium and magnesium ions in wastewater, which differs from Example 5 in that no calcium hydroxide is added to the raw materials of the composite agent.

[0075] Comparative Example 4

[0076] A composition for removing calcium and magnesium ions in wastewater, which is different from Example 5 in that sodium dihydrogen phosphate, sodium carbonate and calcium hydroxide are not added to the raw materials of the composition.

[0077] Comparative Example 5

[0078] A composition for removing calcium and magnesium ions in wastewater, which differs from Example 5 in that no polyaluminum silicate flocculant is added to the raw materials of the composition.

[0079] Performance testing

[0080] The supernatants obtained in Examples 1-5 and Comparative Examples 1-5 were then used to determine the contents of calcium and magnesium ions according to GB / T15452-2009 "Determination of calcium and magnesium ions in industrial circulating cooling water - EDTA titration method". The test results are shown in Table 1.

[0081] Table 1 Test results

[0082]

[0083]

[0084] As can be seen from Table 1, the composition of the present application, through the synergistic effect between the raw materials, has a calcium ion removal rate of 93.1-98.5%, and a magnesium ion removal rate of 97.3-99.8%. It has a good removal rate for calcium and magnesium ions in wastewater, and also has the advantages of low cost and easy use.

[0085] By comparing Example 5 with Comparative Examples 1-4, it can be seen that sodium dihydrogen phosphate, sodium carbonate and calcium hydroxide are added to the composite agent, and the synergistic effect between sodium dihydrogen phosphate, sodium carbonate and calcium hydroxide effectively improves the removal rate of calcium and magnesium ions in the wastewater. By comparing Example 5 with Comparative Example 5, it can be seen that adding a flocculant to the composite agent and the synergistic effect of polysilicate aluminum can effectively reduce the concentration of calcium and magnesium ions in the wastewater in a short time, and the composite agent has the advantages of high removal rate, simple process, convenient operation, stable and reliable operation.

[0086] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0087] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A composition for removing calcium and magnesium ions in wastewater, characterized in that: Including a compounding agent and a flocculant, the compounding agent includes the following components by weight percentage: Sodium dihydrogen phosphate 20-40%, sodium carbonate 50-70%, calcium hydroxide 5-10%; The flocculant is a polyaluminium silicate flocculant; The flocculant accounts for 0.2-0.4% of the mass of the composite agent.

2. A composition for removing calcium and magnesium ions in wastewater according to claim 1, characterized in that: In terms of mass percentage, the composite comprises the following components: Sodium dihydrogen phosphate 25%, sodium carbonate 65%, calcium hydroxide 10%; The flocculant accounts for 0.3% of the mass of the composite agent.

3. A composition for removing calcium and magnesium ions in wastewater according to claim 2, characterized in that: The polyaluminum silicate flocculant is prepared by the following method: adding polyaluminum silicate powder into water and mixing evenly to obtain the polyaluminum silicate flocculant, wherein the mass ratio of the polyaluminum silicate powder to water is 1:

10.

4. The method for using the composition for removing calcium and magnesium ions in wastewater according to claim 3, characterized in that: The following steps are involved: (1) firstly, disodium hydrogen phosphate, sodium carbonate and calcium hydroxide are mixed uniformly to obtain a composite agent; (2) Add a compounding agent to the wastewater, stir and react for 2-10 minutes, then add a flocculant, continue stirring, react for 10-20 minutes, then let it stand for 10-20 minutes to form a precipitate and a supernatant, and remove the precipitate to complete the removal of calcium and magnesium ions in the wastewater.

5. The method for using the composition for removing calcium and magnesium ions in wastewater according to claim 4, characterized in that: The concentration of calcium ions in the wastewater is ≤500 PPM, the concentration of magnesium ions in the wastewater is ≤300 PPM, and the usage of the composite agent in the wastewater is 1-2 g / L.

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