A method for treating fluorine-containing wastewater

Abstract

This invention discloses a method for treating fluoride-containing wastewater, comprising the following steps: introducing the fluoride-containing wastewater into an electrolytic cell, adjusting the pH of the wastewater to 5-7, and performing electrolysis; the anode of the electrolytic cell is an alloy material composed of aluminum, magnesium, and manganese, and the cathode is composed of the same or different metals or non-metals; the anode material generates Al during the electrolysis process. 3+ Mg 2+ Mn 2+ Cations and F ‑ Anions combine to form multi-component precipitates of AlF3, MgF2, and MnF2, reducing the fluoride ion concentration in wastewater. The method of this invention is simple and has low operating costs, significantly reducing the high operating and sludge disposal costs of traditional methods for treating fluoride-containing industrial wastewater. It provides a more advanced treatment solution for fluoride-containing industrial wastewater generated by industries such as electronics processing and photovoltaics.

Description

Technical Field

[0001] This invention relates to a method for treating industrial wastewater, and more particularly to a method for treating fluoride-containing wastewater. Background Technology

[0002] Wastewater from industries such as electronics manufacturing and photovoltaics often contains fluoride. Fluoride concentrations exceeding 1 mg / L in the aquatic environment can cause significant harm.

[0003] Currently, most defluoridation processes involve adding chemicals. The first stage involves adding calcium oxide or calcium chloride to form calcium fluoride precipitate, removing most fluoride ions, but this still doesn't meet standards. The second stage involves adding PAC and PAM flocculants to further reduce the fluoride ion concentration in the wastewater. While this removes fluoride to some extent, it often still doesn't meet standards. The third stage involves adding defluorinating agents, often ion exchange resins or adsorbents, which can control fluoride ions in the wastewater to meet discharge standards, but these agents are expensive. Using chemicals to achieve compliant discharge of fluoride-containing industrial wastewater involves excessive amounts of chemicals, which are ultimately discharged as solid waste. The disposal of this solid waste also incurs costs. Therefore, the combined cost of the chemicals used and the solid waste produced is very high, generally around 30-40 yuan / m³. 3 Wastewater.

[0004] In addition, there is membrane filtration, which uses the reverse osmosis membrane's ability to remove fluoride ions from wastewater. This method relies on the premise that the concentration of other pollutants in the fluoride-containing industrial wastewater cannot be too high; otherwise, the reverse osmosis membrane is very prone to clogging. The biggest problem is that the retained fluoride-containing concentrate still cannot be treated. Furthermore, reverse osmosis membranes are very expensive to manufacture and replace, making this method less practically valuable. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a simple and low-cost method for treating fluoride-containing wastewater.

[0006] Technical solution: The method for treating fluoride-containing wastewater according to the present invention includes the following steps:

[0007] Fluorine-containing wastewater is fed into an electrolytic cell, and the pH value of the wastewater is adjusted to 5-7 for electrolysis.

[0008] The anode of the electrolytic cell is an alloy material composed of aluminum, magnesium, and manganese, while the cathode is composed of the same or different metals or non-metals; the anode material generates Al during the electrolysis process. 3+ Mg 2+ Mn 2+ Cations and F -Anions combine to produce multi-component precipitates of AlF3, MgF2, and MnF2, which reduces the concentration of fluoride ions in wastewater.

[0009] The alloy material composed of aluminum, magnesium, and manganese comprises, by mass percentage: aluminum: 50%–70%; magnesium: 20%–30%; manganese: 10%–20%; the alloy material is obtained by melting aluminum, magnesium, and manganese elements; the melting method is existing technology, and the content of impurity elements in the alloy is negligible.

[0010] The cathode is at least one of copper, titanium, lead, or graphite.

[0011] The voltage during the electrolysis process is controlled at 2-10V, the current at 0-2A, and the electrolysis time at 4min-4h.

[0012] In this process, acid or alkali is added to the electrolytic cell to adjust the pH of the reaction system to 5-7.

[0013] The electrolysis process is carried out under stirring conditions.

[0014] In this process, the precipitates formed in the wastewater after the reaction are separated from the water by sedimentation or filtration.

[0015] Beneficial Effects: Compared with existing technologies, this invention achieves the following significant effects: The method of this invention can significantly reduce the high operating costs and sludge disposal costs of traditional methods when treating fluoride-containing industrial wastewater. Furthermore, when treating wastewater with high concentrations of fluoride ions, it can still significantly reduce the fluoride ion concentration while maintaining low operating costs. This invention provides a more advanced treatment solution for fluoride-containing industrial wastewater generated by the electronics processing industry, photovoltaic industry, and other related sectors. Detailed Implementation

[0016] The present invention will now be described in further detail.

[0017] Example 1

[0018] Fluorine-containing wastewater is fed into an electrolytic cell, and the pH value of the wastewater is adjusted to 5 for electrolysis. The anode of the electrolytic cell is an alloy material composed of aluminum, magnesium, and manganese, and the cathode is graphite. Al is produced by the anode material during electrolysis. 3+ Mg 2+ Mn 2+ Cations and F -Anions combine to produce multi-component precipitates of AlF3, MgF2, and MnF2, reducing the concentration of fluoride ions in the wastewater. The alloy material, composed of aluminum, magnesium, and manganese, comprises, by mass percentage: aluminum: 70%; magnesium: 20%; manganese: 10%. The alloy material of this invention is obtained by melting aluminum, magnesium, and manganese elements using existing techniques; the content of impurity elements in the alloy is negligible.

[0019] The fluoride ion concentration in the fluoride-containing industrial wastewater was 2000 mg / L. The electrolytic cell voltage was 4.8V, the current was 0.4A, and the reaction time was 4 hours. The fluoride ion concentration in the effluent after the reaction was 1.5 mg / L. The operating cost was 7 yuan / m³. 3 Wastewater.

[0020] Note: The general calculation method for operating costs is: [(current * voltage * reaction time) / water volume treated] * electricity price per unit.

[0021] Example 2

[0022] Fluorine-containing wastewater is fed into an electrolytic cell, and the pH value of the wastewater is adjusted to 6 for electrolysis. The anode of the electrolytic cell is an alloy material composed of aluminum, magnesium, and manganese, and the cathode is copper. Al is produced by the anode material during electrolysis. 3+ Mg 2+ Mn 2+ Cations and F - Anions combine to form multi-component precipitates of AlF3, MgF2, and MnF2, reducing the concentration of fluoride ions in the wastewater. The alloy material composed of aluminum, magnesium, and manganese comprises, by mass percentage: aluminum: 70%; magnesium: 20%; manganese: 10%.

[0023] The fluoride ion concentration in the fluoride-containing industrial wastewater was 230 mg / L. The electrolytic cell voltage was 10V, the current was 0.5A, and the reaction time was 1.0 h. The fluoride ion concentration in the effluent after the reaction was 1.0 mg / L. The operating cost was 2.5 yuan / m³. 3 Wastewater.

[0024] Example 3

[0025] Fluorine-containing wastewater is fed into an electrolytic cell, and the pH value of the wastewater is adjusted to 6 for electrolysis. The anode of the electrolytic cell is an alloy material composed of aluminum, magnesium, and manganese, and the cathode is titanium. Al is produced by the anode material during electrolysis. 3+ Mg 2+ Mn 2+ Cations and F - Anions combine to form multi-component precipitates of AlF3, MgF2, and MnF2, reducing the concentration of fluoride ions in the wastewater. The alloy material composed of aluminum, magnesium, and manganese comprises, by mass percentage: aluminum: 70%; magnesium: 20%; manganese: 10%.

[0026] The fluoride ion concentration in the fluoride-containing industrial wastewater was 6.2 mg / L. The electrolytic cell voltage was 2.8V, the current was 1.65A, the reaction time was 4 minutes, and the fluoride ion concentration in the effluent after the reaction was 0.8 mg / L. The operating cost was 0.06 yuan / m³. 3 Wastewater.

[0027] Example 4

[0028] Fluorine-containing wastewater is fed into an electrolytic cell, and the pH value of the wastewater is adjusted to 6 for electrolysis. The anode of the electrolytic cell is an alloy material composed of aluminum, magnesium, and manganese, and the cathode is titanium. Al is produced by the anode material during electrolysis. 3+ Mg 2+ Mn 2+ Cations and F - Anions combine to form multi-component precipitates of AlF3, MgF2, and MnF2, reducing the concentration of fluoride ions in the wastewater. The alloy material composed of aluminum, magnesium, and manganese comprises, by mass percentage: aluminum: 50%; magnesium: 30%; manganese: 20%.

[0029] The fluoride ion concentration in the fluoride-containing industrial wastewater was 6.2 mg / L. The electrolytic cell voltage was 2.8V, the current was 1.65A, the reaction time was 4 minutes, and the fluoride ion concentration in the effluent after the reaction was 1.1 mg / L. The operating cost was 0.06 yuan / m³. 3 Wastewater.

[0030] Example 5

[0031] Fluorine-containing wastewater is fed into an electrolytic cell, and the pH value of the wastewater is adjusted to 6 for electrolysis. The anode of the electrolytic cell is an alloy material composed of aluminum, magnesium, and manganese, and the cathode is titanium. Al is produced by the anode material during electrolysis. 3+ Mg 2+ Mn 2+ Cations and F - Anions combine to form multi-component precipitates of AlF3, MgF2, and MnF2, reducing the concentration of fluoride ions in the wastewater. The alloy material composed of aluminum, magnesium, and manganese comprises, by mass percentage: aluminum: 60%; magnesium: 25%; manganese: 15%.

[0032] The fluoride ion concentration in the fluoride-containing industrial wastewater was 6.2 mg / L. The electrolytic cell voltage was 2.8V, the current was 1.65A, the reaction time was 4 minutes, and the fluoride ion concentration in the effluent after the reaction was 1.0 mg / L. The operating cost was 0.06 yuan / m³. 3 Wastewater.

[0033] Comparative Example 1

[0034] Fluorine-containing wastewater is fed into an electrolytic cell, and the pH value of the wastewater is adjusted to 6 for electrolysis. The anode of the electrolytic cell is made of pure aluminum, and the cathode is made of titanium. Al is produced by the anode material during electrolysis. 3+ Cations and F - The anions combine to form AlF3 precipitate, which reduces the concentration of fluoride ions in the wastewater.

[0035] The fluoride ion concentration in the fluoride-containing industrial wastewater was 6.2 mg / L. The electrolytic cell voltage was 2.8V, the current was 1.65A, the reaction time was 2 hours, and the fluoride ion concentration in the effluent after the reaction was 3.0 mg / L. The operating cost was 5 yuan / m³. 3 Wastewater.

[0036] Comparative Example 2

[0037] Fluorine-containing wastewater is fed into an electrolytic cell, and the pH value of the wastewater is adjusted to 6 for electrolysis. The anode of the electrolytic cell is made of pure magnesium, and the cathode is made of titanium. Mg produced by the anode material during electrolysis... 2+ Cations and F - The anions combine to form MgF2 precipitate, which reduces the concentration of fluoride ions in the wastewater.

[0038] The fluoride ion concentration in the fluoride-containing industrial wastewater was 6.2 mg / L. The electrolytic cell voltage was 2.8V, the current was 1.65A, the reaction time was 2 hours, and the fluoride ion concentration in the effluent after the reaction was 4.5 mg / L. The operating cost was 5 yuan / m³. 3 Wastewater.

[0039] Comparative Example 3

[0040] Fluorine-containing wastewater is fed into an electrolytic cell, and the pH value of the wastewater is adjusted to 6 for electrolysis. The anode of the electrolytic cell is made of pure manganese, and the cathode is made of titanium. Mn is generated from the anode material during electrolysis. 2+ Cations and F - Anions combine to form MnF2 precipitate, which reduces the concentration of fluoride ions in the wastewater.

[0041] The fluoride ion concentration in the fluoride-containing industrial wastewater was 6.2 mg / L. The electrolytic cell voltage was 2.8V, the current was 1.65A, the reaction time was 2 hours, and the fluoride ion concentration in the effluent after the reaction was 5.1 mg / L. The operating cost was 5 yuan / m³. 3 Wastewater.

[0042] Comparative Example 4

[0043] Fluorine-containing wastewater is fed into an electrolytic cell, and the pH value of the wastewater is adjusted to 6 for electrolysis. The anode of the electrolytic cell is made of pure iron, and the cathode is made of titanium. Fe is generated during the electrolysis process by the anode material. 2+ Cations and F -The anions combine to form FeF2 precipitate, which reduces the concentration of fluoride ions in the wastewater.

[0044] The fluoride ion concentration in the fluoride-containing industrial wastewater was 6.2 mg / L. The electrolytic cell voltage was 2.8V, the current was 1.65A, the reaction time was 2 hours, and the fluoride ion concentration in the effluent after the reaction was 5.8 mg / L. The operating cost was 5 yuan / m³. 3 Wastewater.

[0045] Comparative Example 5

[0046] Fluorine-containing wastewater is fed into an electrolytic cell, and the pH value of the wastewater is adjusted to 6 for electrolysis. The anode of the electrolytic cell is an alloy material composed of aluminum, magnesium, and manganese, and the cathode is titanium. Al is produced by the anode material during electrolysis. 3+ Mg 2+ Mn 2+ Cations and F - Anions combine to form multi-component precipitates of AlF3, MgF2, and MnF2, reducing the fluoride ion concentration in the wastewater. The alloy composed of aluminum, magnesium, and manganese comprises, by mass percentage: aluminum: 30%; magnesium: 40%; manganese: 30%.

[0047] The fluoride ion concentration in the fluoride-containing industrial wastewater was 6.2 mg / L. The electrolytic cell voltage was 2.8V, the current was 1.65A, the reaction time was 4 minutes, and the fluoride ion concentration in the effluent after the reaction was 3.3 mg / L. The operating cost was 0.06 yuan / m³. 3 Wastewater.

[0048] Comparative Example 6

[0049] Fluorine-containing wastewater is fed into an electrolytic cell, and the pH value of the wastewater is adjusted to 6 for electrolysis. The anode of the electrolytic cell is an alloy material composed of aluminum, magnesium, and manganese, and the cathode is titanium. Al is produced by the anode material during electrolysis. 3+ Mg 2+ Mn 2+ Cations and F - Anions combine to form multi-component precipitates of AlF3, MgF2, and MnF2, reducing the concentration of fluoride ions in wastewater. The alloy material composed of aluminum, magnesium, and manganese comprises, by mass percentage: aluminum: 80%; magnesium: 15%; manganese: 5%.

[0050] The fluoride ion concentration in the fluoride-containing industrial wastewater was 6.2 mg / L. The electrolytic cell voltage was 2.8V, the current was 1.65A, the reaction time was 4 minutes, and the fluoride ion concentration in the effluent after the reaction was 2.9 mg / L. The operating cost was 0.06 yuan / m³. 3 Wastewater.

[0051] Comparative Example 7

[0052] Fluorine-containing wastewater is fed into an electrolytic cell, and the pH value of the wastewater is adjusted to 6 for electrolysis. The anode of the electrolytic cell is an alloy material composed of aluminum, magnesium, and manganese, and the cathode is titanium. Al is produced by the anode material during electrolysis. 3+ Mg 2+ Mn 2+ Cations and F - Anions combine to form multi-component precipitates of AlF3, MgF2, and MnF2, reducing the concentration of fluoride ions in the wastewater. The alloy material composed of aluminum, magnesium, and manganese comprises, by mass percentage: aluminum: 70%; magnesium: 20%; manganese: 10%.

[0053] The fluoride ion concentration in the fluoride-containing industrial wastewater was 6.2 mg / L. The electrolytic cell voltage was 20V, the current was 5.2A, the reaction time was 4 minutes, and the fluoride ion concentration in the effluent after the reaction was 2.5 mg / L. The operating cost was 1.5 yuan / m³. 3 Wastewater.

Claims

1. A method for treating fluorine-containing wastewater, characterized by, Includes the following steps: Fluorine-containing wastewater is fed into an electrolytic cell, and the pH value of the wastewater is adjusted to 5-7 for electrolysis. The anode of the electrolytic cell is an alloy material composed of aluminum, magnesium, and manganese, while the cathode is composed of the same or different metals or non-metals; the anode material generates Al during the electrolysis process. 3+ Mg 2+ Mn 2+ Cations and F - Anions combine to produce multi-component precipitates of AlF3, MgF2, and MnF2, which reduces the concentration of fluoride ions in wastewater. The alloy material composed of aluminum, magnesium, and manganese comprises, by mass percentage: aluminum: 50%~70%; magnesium: 20%~30%; manganese: 10%~20%; the cathode is at least one of copper, titanium, lead, or graphite; the voltage during the electrolysis process is controlled at 2-10V and the current at 0-2A.

2. The method for treating fluorochemical wastewater according to claim 1, characterized by, The alloy material is obtained by melting aluminum, magnesium, and manganese.

3. The method of treating fluorochemical wastewater according to claim 1, wherein, The electrolysis time is 4 min to 4 h.

4. The method of treating fluorochemical wastewater according to claim 1, wherein Add acid or alkali to the electrolytic cell to adjust the pH of the reaction system to 5-7.

5. The method of treating fluorochemical wastewater of claim 1, wherein, The electrolysis process is carried out under stirring conditions.

6. The method of treating fluorochemical wastewater of claim 1, wherein, The precipitates formed after the reaction are separated from the water by sedimentation or filtration.