Method for removing silicon ions in sewage

Abstract

The invention belongs to the technical field of sewage treatment, and particularly relates to a method for removing silicon ions in sewage. The method for removing the silicon ions in the sewage comprises the following steps: adding an agent into the sewage to be treated to enable silicon elements in the sewage to form silicate radicals, adjusting the pH value of the sewage to be alkaline, then adding seed crystals into the sewage, and mixing and filtering. The method for removing the silicon ions in the sewage has the beneficial effects that the process is simple, the removal efficiency is high, and the cost is low.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and particularly relates to a method for removing silicon ions in sewage. Background Art

[0002] Directly discharging silicon-containing wastewater into rivers, lakes, and other water bodies can cause water opacity and turbidity, and in severe cases, damage the aquatic ecosystem. Silicon-containing wastewater pollution originates from industrial wastewater containing substances such as silicates. These wastewaters contain large amounts of silicates and heavy metal ions. If discharged directly into the natural environment without treatment, they will pollute water sources. The silicates in silicon-containing wastewater will combine with calcium ions in the water to form colloids, affecting water clarity.

[0003] Currently, the main processes for treating silicon-containing wastewater include chemical precipitation and membrane separation, but these methods are not ideal for removing silicon and have problems of low efficiency and high cost. Summary of the Invention

[0004] The present application provides a method for removing silicon ions from sewage, aiming to solve the problems of low efficiency, high cost and unsatisfactory removal effect of the existing technology for removing silicon ions from sewage.

[0005] The present application provides a method for removing silicon ions from sewage, comprising the following steps: adding a reagent to the sewage to be treated to convert the silicon element in the sewage into silicate, adjusting the pH of the sewage to alkaline, and then adding seed crystals to the sewage, mixing and filtering.

[0006] According to some embodiments of the method for removing silicon ions from sewage described in the present application, the hardness of the sewage is 1000-6000 mg / L.

[0007] According to some embodiments of the method for removing silicon ions in wastewater described in the present application, the reagent includes sodium hydroxide.

[0008] According to some embodiments of the method for removing silicon ions from wastewater described in the present application, the amount of the agent added is 100-300 mg / L.

[0009] According to some embodiments of the method for removing silicon ions from wastewater described in the present application, sodium hydroxide is used to adjust the pH of the wastewater.

[0010] According to some embodiments of the method for removing silicon ions from wastewater described in the present application, the pH of the wastewater is adjusted to 8-11.

[0011] According to some embodiments of the method for removing silicon ions from wastewater described in the present application, the seed crystals include one or more of calcite, garnet, magnesium silicate and calcium silicate.

[0012] According to some embodiments of the method for removing silicon ions from wastewater described in the present application, the seed crystals are calcite and calcium silicate.

[0013] According to some embodiments of the method for removing silicon ions from wastewater described in the present application, the particle size of the seed crystal is 1-6 um.

[0014] According to some embodiments of the method for removing silicon ions from wastewater described in the present application, the amount of the seed crystal added is 50-300 mg / L.

[0015] According to some embodiments of the method for removing silicon ions from wastewater described in the present application, the mixing temperature is 20-30° C., and the mixing time is 10-30 minutes.

[0016] The beneficial effects of the present application include: the method for removing silicon ions in wastewater described in the present application has a simple process, high removal efficiency and low cost. DETAILED DESCRIPTION

[0017] The embodiments of the present invention are described in detail below. The examples of the embodiments are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0018] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0019] An embodiment of the present application provides a method for removing silicon ions from sewage, comprising the following steps: adding a reagent to the sewage to be treated to convert the silicon element in the sewage into silicate ions, adjusting the pH of the sewage to alkaline, and then adding seed crystals to the sewage, mixing and filtering.

[0020] The method for removing silicon ions from wastewater described in this application is to add a reagent to make the silicon dioxide in the water form silicate, and at the same time react with HCO3 in the water to form silicate. - The reaction produces CO3 2- , various forms of silicate and Ca in sewage 2+ Mg 2+ 、Al 3+ and CO3 2- and some SO4 2-, various ions collide with each other and reach saturation, thus forming precipitates such as calcium carbonate, calcium silicate, magnesium silicate and magnesium hydroxide. At the same time, precipitates such as CaCO3, Mg(OH)2 and Al(OH)3 or other inorganic precipitates can provide a capture crystal matrix for silica, improving the removal efficiency of silica. When induced crystal seeds are added to the water, some of them will form crystals and adhere to the surface of the crystal seeds, forming heterogeneous nucleation, achieving the purpose of removing silicon ions from wastewater.

[0021] In some embodiments of the present application, the hardness of the sewage is 1000-6000 mg / L, for example, 1000 mg / L, 2500 mg / L, 3200 mg / L, 3800 mg / L, 4300 mg / L, 5600 mg / L, 6000 mg / L, etc.

[0022] In some embodiments of the present application, the agent includes sodium hydroxide.

[0023] In some embodiments of the present application, the added amount of the agent is 100-300 mg / L, for example, 100 mg / L, 120 mg / L, 150 mg / L, 180 mg / L, 220 mg / L, 260 mg / L, 300 mg / L, etc.

[0024] In some embodiments of the present application, sodium hydroxide is used to adjust the pH of the sewage.

[0025] In some embodiments of the present application, the pH of the sewage is adjusted to 8-11, for example, 8, 9, 10, 10.5, 11, etc.

[0026] In some embodiments of the present application, the seed crystals include one or more of calcite, garnet, magnesium silicate and calcium silicate.

[0027] In some embodiments of the present application, the seed crystals are calcite and calcium silicate.

[0028] In some embodiments of the present application, the particle size of the seed crystal is 1-6 um, for example, 1 um, 2 um, 3 um, 5 um, 6 um, etc.

[0029] In some embodiments of the present application, the amount of the seed crystal added is 50-300 mg / L, for example, 50 mg / L, 120 mg / L, 180 mg / L, 230 mg / L, 280 mg / L, 300 mg / L, etc.

[0030] In some embodiments of the present application, the mixing temperature is 20-30°C, for example, 20°C, 25°C, 30°C, etc., and the mixing time is 10-30min, for example, 10min, 15min, 18min, 23min, 30min, etc.

[0031] The technical solution of this application is further described below with reference to specific embodiments.

[0032] Example 1

[0033] A method for removing silicon ions in sewage comprises the following steps: adding sodium hydroxide (the amount of sodium hydroxide added is 100 mg / L) to sewage to be treated (the hardness of the sewage is 5000 mg / L) to convert silicon elements in the sewage into silicate ions; adjusting the pH of the sewage to 8 with sodium hydroxide; then adding calcite and calcium silicate with a particle size of 2-3 μm to the sewage (the amount of calcite and calcium silicate added is 100 mg / L, wherein the mass ratio of calcite to calcium silicate is 1:1); mixing at a temperature of 25° C. for 10 minutes; and filtering.

[0034] Example 2

[0035] The method for removing silicon ions from sewage described in Example 2 is different from that in Example 1 only in that the method for removing silicon ions from sewage described in Example 2 adjusts the pH of the sewage to 9.

[0036] The specific steps include:

[0037] Sodium hydroxide (the amount of sodium hydroxide added is 100 mg / L) is added to the sewage to be treated (the hardness of the sewage is 5000 mg / L) to form silicate ions from the silicon element in the sewage. The pH of the sewage is adjusted to 9 with sodium hydroxide. Then, calcite and calcium silicate with a particle size of 2-3 μm are added to the sewage (the amount of calcite and calcium silicate added is 100 mg / L, and the mass ratio of calcite to calcium silicate is 1:1). The mixture is mixed at a temperature of 25°C for 10 minutes and filtered.

[0038] Example 3

[0039] The method for removing silicon ions from sewage described in Example 3 is different from that in Example 1 only in that the method for removing silicon ions from sewage described in Example 3 adjusts the pH of the sewage to 10.5.

[0040] The specific steps include:

[0041] Sodium hydroxide (the amount of sodium hydroxide added is 100 mg / L) is added to the sewage to be treated (the hardness of the sewage is 5000 mg / L) to form silicate ions from the silicon element in the sewage. The pH of the sewage is adjusted to 10.5 using sodium hydroxide. Then, calcite and calcium silicate with a particle size of 2-3 μm are added to the sewage (the amount of calcite and calcium silicate added is 100 mg / L, and the mass ratio of calcite to calcium silicate is 1:1). The mixture is mixed at a temperature of 25°C for 10 minutes and filtered.

[0042] Example 4

[0043] The method for removing silicon ions from sewage described in Example 4 is different from that in Example 1 only in that the method for removing silicon ions from sewage described in Example 4 adjusts the pH of the sewage to 11.

[0044] The specific steps include:

[0045] Sodium hydroxide (the amount of sodium hydroxide added is 100 mg / L) is added to the sewage to be treated (the hardness of the sewage is 5000 mg / L) to form silicate ions from the silicon element in the sewage. The pH of the sewage is adjusted to 11 using sodium hydroxide. Then, calcite and calcium silicate with a particle size of 2-3 μm are added to the sewage (the amount of calcite and calcium silicate added is 100 mg / L, and the mass ratio of calcite to calcium silicate is 1:1). The mixture is mixed at a temperature of 25°C for 10 minutes and filtered.

[0046] Example 5

[0047] The method for removing silicon ions from sewage described in Example 5 is different from that in Example 1 only in that the method for removing silicon ions from sewage described in Example 5 uses calcite and calcium silicate in a mass ratio of 1:0.5 as seed crystals.

[0048] The specific steps include:

[0049] Sodium hydroxide (the amount of sodium hydroxide added is 100 mg / L) is added to the sewage to be treated (the hardness of the sewage is 5000 mg / L) to form silicate ions from the silicon element in the sewage. The pH of the sewage is adjusted to 8 using sodium hydroxide. Then, calcite and calcium silicate with a particle size of 2-3 μm are added to the sewage (the amount of calcite and calcium silicate added is 100 mg / L, and the mass ratio of calcite to calcium silicate is 1:0.5). The mixture is mixed at a temperature of 25°C for 10 minutes and filtered.

[0050] Example 6

[0051] The method for removing silicon ions from sewage described in Example 6 is different from that in Example 1 only in that the method for removing silicon ions from sewage described in Example 6 uses calcite and calcium silicate in a mass ratio of 1:2 as seed crystals.

[0052] The specific steps include:

[0053] Sodium hydroxide (the amount of sodium hydroxide added is 100 mg / L) is added to the sewage to be treated (the hardness of the sewage is 5000 mg / L) to make the silicon element in the sewage form silicate, and the pH of the sewage is adjusted to 8 with sodium hydroxide. Then, calcite and calcium silicate with a particle size of 2-3 μm are added to the sewage (the amount of calcite and calcium silicate added is 100 mg / L, and the mass ratio of calcite to calcium silicate is 1:2), mixed at a temperature of 25°C for 10 minutes, and filtered.

[0054] Example 7

[0055] The method for removing silicon ions from wastewater described in Example 7 is different from that in Example 1 only in that: in the method for removing silicon ions from wastewater described in Example 7, the amount of seed crystal added is 50 mg / L.

[0056] The specific steps include:

[0057] Sodium hydroxide (the amount of sodium hydroxide added is 100 mg / L) is added to the sewage to be treated (the hardness of the sewage is 5000 mg / L) to form silicate ions from the silicon element in the sewage. The pH of the sewage is adjusted to 8 using sodium hydroxide. Then, calcite and calcium silicate with a particle size of 2-3 μm are added to the sewage (the amount of calcite and calcium silicate added is 50 mg / L, and the mass ratio of calcite to calcium silicate is 1:1). The mixture is mixed at a temperature of 25°C for 10 minutes and filtered.

[0058] Example 8

[0059] The method for removing silicon ions from wastewater described in Example 8 is different from that in Example 1 only in that: in the method for removing silicon ions from wastewater described in Example 8, the amount of seed crystal added is 200 mg / L.

[0060] The specific steps include:

[0061] Sodium hydroxide (the amount of sodium hydroxide added is 100 mg / L) is added to the sewage to be treated (the hardness of the sewage is 5000 mg / L) to form silicate ions from the silicon element in the sewage. The pH of the sewage is adjusted to 8 using sodium hydroxide. Then, calcite and calcium silicate with a particle size of 2-3 μm are added to the sewage (the amount of calcite and calcium silicate added is 200 mg / L, and the mass ratio of calcite to calcium silicate is 1:1). The mixture is mixed at a temperature of 25°C for 10 minutes and filtered.

[0062] The results of the method for removing silicon ions from wastewater described in Examples 1-8 of the present application are shown in Table 1.

[0063] Table 1

[0064] <![CDATA[Ca in sewage 2+ Removal rate]]> <![CDATA[Si in sewage 4+ Removal rate]]> Example 1 84.54％ 90.07％ Example 2 87.10％ 95.54％ Example 3 88.82％ 96.37％ Example 4 83.38％ 89.59％ Example 5 94.47％ 67.72％ Example 6 58.89％ 96.38％ Example 7 69.79％ 41.20％ Example 8 89.92％ 81.28％

[0065] It can be seen from Table 1 that the method for removing silicon ions from sewage described in the present application has a good effect of removing silicon ions and calcium ions.

[0066] Although the above embodiments have been shown and described, it is understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those skilled in the art are all within the scope of protection of the present invention.

Claims

1. A method for removing silicon ions from sewage, characterized in that: The method comprises the following steps: adding a reagent to the sewage to be treated to make the silicon element in the sewage form silicate, adjusting the pH of the sewage to alkaline, then adding crystal seeds to the sewage, mixing and filtering.

2. The method for removing silicon ions from sewage according to claim 1, characterized in that: The hardness of the sewage is 1000-6000 mg / L.

3. The method for removing silicon ions from sewage according to claim 1, characterized in that: The agent includes sodium hydroxide; And / or, the added amount of the agent is 100-300 mg / L.

4. The method for removing silicon ions from sewage according to claim 1, characterized in that: Sodium hydroxide was used to adjust the pH of the wastewater.

5. The method for removing silicon ions from sewage according to claim 1, characterized in that: The pH of the sewage is adjusted to 8-11.

6. The method for removing silicon ions from sewage according to claim 1, characterized in that: The seed crystals include one or more of calcite, garnet, magnesium silicate and calcium silicate.

7. The method for removing silicon ions from sewage according to claim 1, characterized in that: The seed crystals are calcite and calcium silicate.

8. The method for removing silicon ions from sewage according to claim 1, characterized in that: The particle size of the seed crystal is 1-6 μm.

9. The method for removing silicon ions from sewage according to claim 1, characterized in that: The amount of the seed crystal added is 50-300 mg / L.

10. The method for removing silicon ions from sewage according to claim 1, characterized in that: The mixing temperature is 20-30° C., and the mixing time is 10-30 min.