Fluorine-containing wastewater treatment method

Abstract

The invention discloses a fluorine-containing wastewater treatment method which comprises the following steps: introducing fluorine-containing wastewater into an electrolytic bath, adjusting the pH value of the fluorine-containing wastewater to 5-7, and carrying out electrolysis; the anode of the electrolytic bath is made of an alloy material consisting of aluminum, magnesium and manganese alloys, and the cathode of the electrolytic bath is made of the same or different metals or non-metals; al < 3 + >, Mg < 2 + > and Mn < 2 + > cations generated in the electrolysis process of the anode material are combined with F <-> anions to generate AlF3, MgF2 and MnF2 multi-element precipitation products, so that the concentration of fluorine ions in the wastewater is reduced. The method provided by the invention is simple in process and low in operation cost, can greatly reduce high operation cost and sludge treatment cost when the fluorine-containing industrial wastewater is treated by a traditional method, and provides a relatively advanced treatment scheme for the fluorine-containing industrial wastewater generated in the electronic processing industry, the photovoltaic industry and the like.

Description

Technical Field

[0001] The invention relates to a method for treating industrial waste water, in particular to a method for treating fluorine-containing waste water. Background Art

[0002] Wastewater generated by industries such as electronic processing and photovoltaics often contains fluoride. When the concentration of fluoride in the water environment exceeds 1 mg / L, it will cause great harm.

[0003] At present, most fluoride removal processes are to add chemicals. In the first stage, calcium oxide or calcium chloride is added to form calcium fluoride precipitation, which removes most of the fluoride ions, but still cannot meet the standards. In the second stage, PAC and PAM flocculants are added to further reduce the fluoride ion concentration in the wastewater. Although fluoride is further removed to a certain extent, it still cannot meet the standards in most cases. In the third stage, defluoridation agents are added. Defluoridation agents are often some ion exchange resins or adsorbents, which can control the fluoride ions in the wastewater to meet the discharge standards, but the defluoridation agents themselves are expensive. The method of adding chemicals to make fluorine-containing industrial wastewater meet the discharge standards is excessive, and the added chemicals are eventually discharged in the form of solid waste. The disposal of solid waste costs money. Therefore, the sum of the cost of the chemicals used and the solid waste produced by this method is very high, generally 30-40 yuan / m 3 Wastewater.

[0004] In addition, there is also a membrane filtration method, which uses the interception capacity of reverse osmosis membranes to remove fluoride from wastewater. The premise of this method is that the concentration of other pollutants in fluorine-containing industrial wastewater cannot be too high, otherwise the reverse osmosis membrane is very easy to clog, and the biggest problem is that the intercepted fluorine-containing concentrated water still has no way to be treated. At the same time, the cost of reverse osmosis membranes is also very expensive, and the cost of replacing membranes is very high, so this method has low practical application value. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a method for treating fluorine-containing wastewater with a simple process and low operating cost.

[0006] Technical solution: The method for treating fluorine-containing wastewater of the present invention comprises the following steps:

[0007] Passing the fluorine-containing wastewater into the electrolytic cell, adjusting the pH value of the fluorine-containing wastewater to 5-7, and performing electrolysis;

[0008] The anode of the electrolytic cell is an alloy material composed of aluminum, magnesium and manganese alloy, and the cathode is composed of the same or different metals or non-metals; the Al generated by the anode material during the electrolysis process 3+ Mg 2+ , Mn 2+ Cations and F -Anions combine to produce AlF3, MgF2, and MnF2 multi-precipitation products, reducing the fluoride ion concentration in the wastewater.

[0009] Among them, the alloy material composed of aluminum, magnesium and manganese includes, by mass percentage: aluminum: 50% to 70%; magnesium: 20% to 30%; manganese: 10% to 20%; the alloy material is obtained by smelting aluminum, magnesium and manganese elements; the smelting method is the existing technology, and the content of impurity elements in the alloy is negligible.

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

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

[0012] Wherein, acid or alkali is added into the electrolytic cell to adjust the pH value of the reaction system to 5-7.

[0013] Wherein, the electrolysis process is carried out under stirring conditions.

[0014] The wastewater after the reaction is separated from the water by sedimentation or filtration.

[0015] Beneficial effects: Compared with the prior art, the present invention has the following significant effects: the method of the present invention can significantly reduce the high operating costs and sludge disposal costs of the traditional method in treating fluorine-containing industrial wastewater, and when treating wastewater with a high concentration of fluorine ions, the fluorine ion concentration can still be significantly reduced, and the operating costs are kept at a low level. The present invention provides a relatively advanced treatment solution for fluorine-containing industrial wastewater generated by the electronic processing industry, photovoltaic industry, etc. DETAILED DESCRIPTION

[0016] The present invention is described in further detail below.

[0017] Example 1

[0018] The fluorine-containing wastewater is passed into the electrolytic cell, the pH value of the fluorine-containing wastewater is adjusted to 5, and electrolysis is performed; the anode of the electrolytic cell is an alloy material composed of aluminum, magnesium, and manganese alloy, and the cathode is graphite; the Al produced by the anode material during the electrolysis process 3+ Mg 2+ , Mn 2+ Cations and F -The anions combine to produce AlF3, MgF2, and MnF2 multi-precipitation products, thereby reducing the fluoride ion concentration in the wastewater. The alloy material composed of aluminum, magnesium, and manganese alloys includes, by mass percentage, aluminum: 70%; magnesium: 20%; and manganese: 10%. The alloy material of the present invention is obtained by smelting aluminum, magnesium, and manganese elements. The specific smelting method is the prior art, and the content of impurity elements in the alloy is negligible.

[0019] Among them, the fluoride ion concentration in fluorine-containing industrial wastewater is 2000mg / L, the electrolytic cell voltage is 4.8V, the current is 0.4A, and the reaction time is 4h. After the reaction, the fluoride ion concentration in the effluent is 1.5mg / L. The operating cost is 7 yuan / m 3 Wastewater.

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

[0021] Example 2

[0022] The fluorine-containing wastewater is passed into the electrolytic cell, the pH value of the fluorine-containing wastewater is adjusted to 6, and electrolysis is performed; the anode of the electrolytic cell is an alloy material composed of aluminum, magnesium, and manganese alloy, and the cathode is copper; the Al produced by the anode material during the electrolysis process 3+ Mg 2+ , Mn 2+ Cations and F - The anions combine to produce AlF3, MgF2, and MnF2 multi-precipitation products, which reduce the fluoride ion concentration in the wastewater. Among them, the alloy material composed of aluminum, magnesium, and manganese alloy includes the following by mass percentage: aluminum: 70%; magnesium: 20%; manganese: 10%.

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

[0024] Example 3

[0025] Fluoride-containing wastewater is passed into an electrolytic cell, and the pH value of the fluoride-containing wastewater is adjusted to 6 for electrolysis. The anode of the electrolytic cell is an alloy material composed of aluminum, magnesium and manganese alloy, and the cathode is titanium. The Al produced by the anode material during the electrolysis process 3+ Mg 2+ , Mn 2+ Cations and F - The anions combine to produce AlF3, MgF2, and MnF2 multi-precipitation products, which reduce the fluoride ion concentration in the wastewater. Among them, the alloy material composed of aluminum, magnesium, and manganese alloy includes the following by mass percentage: aluminum: 70%; magnesium: 20%; manganese: 10%.

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

[0027] Example 4

[0028] Fluoride-containing wastewater is passed into an electrolytic cell, and the pH value of the fluoride-containing wastewater is adjusted to 6 for electrolysis. The anode of the electrolytic cell is an alloy material composed of aluminum, magnesium and manganese alloy, and the cathode is titanium. The Al produced by the anode material during the electrolysis process 3+ Mg 2+ , Mn 2+ Cations and F - The anions combine to produce AlF3, MgF2, and MnF2 multi-precipitation products, which reduce the fluoride ion concentration in the wastewater. Among them, the alloy material composed of aluminum, magnesium, and manganese alloy includes aluminum: 50%; magnesium: 30%; manganese: 20% by mass percentage.

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

[0030] Example 5

[0031] Fluoride-containing wastewater is passed into an electrolytic cell, and the pH value of the fluoride-containing wastewater is adjusted to 6 for electrolysis. The anode of the electrolytic cell is an alloy material composed of aluminum, magnesium and manganese alloy, and the cathode is titanium. The Al produced by the anode material during the electrolysis process 3+ Mg 2+ , Mn 2+ Cations and F - The anions combine to produce AlF3, MgF2, and MnF2 multi-precipitation products, which reduce the fluoride ion concentration in the wastewater. Among them, the alloy material composed of aluminum, magnesium, and manganese alloy includes aluminum: 60%; magnesium: 25%; manganese: 15% by mass.

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

[0033] Comparative Example 1

[0034] The fluorine-containing wastewater is passed into the electrolytic cell, the pH value of the fluorine-containing wastewater is adjusted to 6, and electrolysis is performed; the anode of the electrolytic cell is made of pure aluminum material, and the cathode is made of titanium; the Al produced by the anode material during the electrolysis process 3+ Cations and F - The anions combine to produce AlF3 precipitation products, reducing the fluoride ion concentration in the wastewater.

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

[0036] Comparative Example 2

[0037] The fluorine-containing wastewater is passed into the electrolytic cell, the pH value of the fluorine-containing wastewater is adjusted to 6, and electrolysis is performed; the anode of the electrolytic cell is pure magnesium material, and the cathode is titanium; the Mg produced by the anode material during the electrolysis process 2+ Cations and F - The anions combine to produce MgF2 precipitation product, reducing the fluoride ion concentration in the wastewater.

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

[0039] Comparative Example 3

[0040] The fluorine-containing wastewater is passed into the electrolytic cell, the pH value of the fluorine-containing wastewater is adjusted to 6, and electrolysis is performed; the anode of the electrolytic cell is pure manganese material, and the cathode is titanium; the Mn generated by the anode material during the electrolysis process 2+ Cations and F - The anions combine to produce MnF2 precipitation products, reducing the fluoride ion concentration in the wastewater.

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

[0042] Comparative Example 4

[0043] The fluorine-containing wastewater is passed into the electrolytic cell, the pH value of the fluorine-containing wastewater is adjusted to 6, and electrolysis is performed; the anode of the electrolytic cell is made of pure iron material, and the cathode is made of titanium; the Fe 2+ Cations and F -The anions combine to produce FeF2 precipitation products, reducing the fluoride ion concentration in the wastewater.

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

[0045] Comparative Example 5

[0046] Fluoride-containing wastewater is passed into an electrolytic cell, and the pH value of the fluoride-containing wastewater is adjusted to 6 for electrolysis. The anode of the electrolytic cell is an alloy material composed of aluminum, magnesium and manganese alloy, and the cathode is titanium. The Al produced by the anode material during the electrolysis process 3+ Mg 2+ , Mn 2+ Cations and F - The anions combine to produce AlF3, MgF2, and MnF2 multi-precipitation products, which reduce the fluoride ion concentration in the wastewater. Among them, the alloy composed of aluminum, magnesium, and manganese includes aluminum: 30%; magnesium: 40%; manganese: 30% by mass.

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

[0048] Comparative Example 6

[0049] Fluoride-containing wastewater is passed into an electrolytic cell, and the pH value of the fluoride-containing wastewater is adjusted to 6 for electrolysis. The anode of the electrolytic cell is an alloy material composed of aluminum, magnesium and manganese alloy, and the cathode is titanium. The Al produced by the anode material during the electrolysis process 3+ Mg 2+ , Mn 2+ Cations and F - The anions combine to produce AlF3, MgF2, and MnF2 multi-precipitation products, which reduce the fluoride ion concentration in the wastewater. The alloy material composed of aluminum, magnesium, and manganese alloys includes the following by mass percentage: aluminum: 80%; magnesium: 15%; manganese: 5%.

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

[0051] Comparative Example 7

[0052] Fluoride-containing wastewater is passed into an electrolytic cell, and the pH value of the fluoride-containing wastewater is adjusted to 6 for electrolysis. The anode of the electrolytic cell is an alloy material composed of aluminum, magnesium and manganese alloy, and the cathode is titanium. The Al produced by the anode material during the electrolysis process 3+ Mg 2+ , Mn 2+ Cations and F - The anions combine to produce AlF3, MgF2, and MnF2 multi-precipitation products, which reduce the fluoride ion concentration in the wastewater. Among them, the alloy material composed of aluminum, magnesium, and manganese alloy includes the following by mass percentage: aluminum: 70%; magnesium: 20%; manganese: 10%.

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

Claims

1. A method for treating fluorine-containing wastewater, characterized in that: The following steps are involved: Passing the fluorine-containing wastewater into the electrolytic cell, adjusting the pH value of the fluorine-containing wastewater to 5-7, and performing electrolysis; The anode of the electrolytic cell is an alloy material composed of aluminum, magnesium and manganese alloy, and the cathode is composed of the same or different metals or non-metals; the Al generated by the anode material during the electrolysis process 3+ Mg 2+ , Mn 2+ Cations and F - Anions combine to produce AlF3, MgF2, and MnF2 multi-precipitation products, reducing the fluoride ion concentration in the wastewater.

2. The method for treating fluorine-containing wastewater according to claim 1, characterized in that: The alloy material composed of aluminum, magnesium and manganese includes, by mass percentage, aluminum: 50% to 70%; magnesium: 20% to 30%; and manganese: 10% to 20%.

3. The method for treating fluorine-containing wastewater according to claim 1, characterized in that: The alloy material is obtained by smelting aluminum, magnesium and manganese elements.

4. The method for treating fluorine-containing wastewater according to claim 1, characterized in that: The cathode is at least one of copper, titanium, lead or graphite.

5. The method for treating fluorine-containing wastewater according to claim 1, characterized in that: The voltage during the electrolysis process is controlled to be 2-10V and the current to be 0-2A.

6. The method for treating fluorine-containing wastewater according to claim 1, characterized in that: The electrolysis time is 4 min-4 h.

7. The method for treating fluorine-containing wastewater according to claim 1, characterized in that: Acid or alkali is added into the electrolytic cell to adjust the pH value of the reaction system to 5-7.

8. The method for treating fluorine-containing wastewater according to claim 1, characterized in that: The electrolysis process is carried out under stirring conditions.

9. The method for treating fluorine-containing wastewater according to claim 1, characterized in that: The wastewater after the reaction is separated from the water by sedimentation or filtration.