CN110451704A - A kind of processing method of fluorine-containing recycle-water - Google Patents

Abstract

The invention discloses a treatment method for fluorine-containing reused water. The specific steps are as follows: (1) pretreatment; (2) flocculation and sedimentation; (3) filtration-reverse osmosis membrane filtration; (4) TOC degradation and ultraviolet sterilization; ( 5) EDI treatment; (6) TOC degradation and ultraviolet sterilization; (7) precision filtration; the advantages of the present invention are that the effluent water quality can reach the ultrapure water standard, and the fluorine removal efficiency is high, the waste water reuse rate is high, and the operation cost is low.

Description

A treatment method for fluorine-containing reused water

technical field

The invention belongs to the field of wastewater treatment, and more specifically relates to a treatment method for fluorine-containing reused water in the electronics industry.

Background technique

With the rapid development of electronic products in recent years, the discharge of wastewater from the electronics industry is increasing day by day. In addition, due to the increasingly complex preparation process of the electronics industry, the difficulty of electronic wastewater treatment is also increasing. At present, the main sources of electronic wastewater include grinding, chemical etching, black/brown oxidation, deburring, desmear removal, plated through holes, tin plating, copper plating, tin stripping, solder resist green paint, development and molding cleaning. Therefore, electronic wastewater contains a variety of substances that need to be treated and have negative effects on the environment, including fluoride ions. Taking semiconductor industrial units such as photovoltaic cell manufacturing and electronics factories as examples, a large amount of hydrofluoric acid is used in wafer etching and quartz cleaning, and the etching solution used in the wet etching process contains hydrofluoric acid and ammonium fluoride. In the cleaning process, fluoride ions will enter the electronic wastewater along with pure water, and the fluorine concentration in the generated fluorine-containing acidic wastewater can reach more than 1000mg/L. Fluorine poses a huge threat to the health of humans and animals, and can cause human death in severe cases. Therefore, the direct discharge of these fluorine-containing wastewater may pose a huge threat to the environment. In order to avoid pollution of groundwater, soil, and surface water, electronic wastewater must be After defluoridation treatment to make it reach the emission limit, such as Shanghai's current "Semiconductor Industry Pollutant Discharge Standard" (DB31/445-2006) stipulates that the fluoride ion emission limit is 20mg/L, Beijing's current "Water Pollutants The Comprehensive Emission Standard (DB11/307-2013) stipulates that the limit of fluoride discharged into the public sewage treatment system is 10mg/L, and the World Health Organization recommends that the concentration limit of fluoride in drinking water be 1.5mg/L.

The existing treatment methods of fluorine-containing wastewater mainly include precipitation method, adsorption method, electrochemical method and membrane treatment method. The precipitation method is mainly to add substances that have coagulation ability or precipitate with fluoride (lime, neutral calcium salt, aluminum salt, iron salt and PAM, etc.) Coagulation or precipitation, and then the process of removing fluoride ions from water by filtration; this method is simple, convenient, low cost, large amount of wastewater to be treated, and the effluent can basically reach the wastewater discharge standard (10-20mg/L), but it is not suitable for Drinking water treatment is suitable for industrial applications, and the reaction speed is slow, and the amount of waste residue in the reaction process is large. It is difficult to treat the effluent water below 10mg/L. The adsorption method is a means of adding a specific adsorbent to the wastewater to remove fluoride. The basic process includes the following four steps: (1) The solute molecules diffuse from the main body of the solution through the boundary layer on the surface of the adsorbent to the outside of the adsorbent. (2) solute molecules diffuse through the pores and migrate from the outer surface of the adsorbent to the inside of the adsorbent micropores, which is called internal diffusion; (3) fluoride ions diffuse along the surface of the pore surface; (4) ) fluoride ions are adsorbed on the pore surface. Typical adsorbents include active metal oxides, zeolites and resins; however, the regeneration of active metal oxides is complicated and needs to be burned at 420-1000°C. The amount is large and the adsorption time is long, so it is only suitable for the treatment of fluorinated water in rural areas, not for the use of large-scale treatment equipment; in the process of defluoridation of ion exchange resin, the defluoridation effect will be affected by other minerals in wastewater Influence, so that the quality of the effluent is reduced; and the resin is easily polluted by other impurities, resulting in poor fluoride removal effect. Electrodialysis is under the action of a direct current electric field, using the selective permeability of the ion exchange membrane, the charged ions migrate through the ion exchange membrane in a directional manner, and are separated from the aqueous solution and other uncharged components, thereby realizing the concentration, desalination, and removal of the solution. For refining and purification purposes. Simple equipment, easy operation, stable operation, continuous water production, easy to realize automatic control, etc. Clean and thorough removal of fluorine, good quality of effluent, automatic operation, easy management; suitable for raw water with a salt content of 1-5g/L High-fluorine brackish water with a fluorine content of less than 5mg/L is suitable for centralized drinking water defluoridation projects in Kuchengshui areas in Northwest my country, Shandong and other places; however, it has strict requirements on water quality and requires pretreatment of raw water; treatment The cost is expensive (about 6 yuan/t water), and the equipment investment is large; other beneficial components have been removed, and the fluoride removal efficiency needs to be improved; in terms of technology, there is membrane polarization scaling, and the type and life of the membrane are yet to be studied; the energy consumption is large, The operation is not stable enough and with the rapid development of RO, the membrane treatment method is to use a membrane made of organic polymer or inorganic material, and use the concentration difference of the solution on both sides of the membrane to make the solute or solvent in the solution on one side penetrate into the other. One side, so as to achieve the purpose of separating the solute from the solvent. The advantage of membrane separation is that the separation effect is good. However, membrane separation technology also has its limitations, such as the need for pretreatment of the solution, and the disadvantages of low throughput.

Based on the above factors, in the face of fluorine-containing wastewater, a combined process has begun to appear. For example, in the Chinese invention patent application document with the publication (announcement) number CN105036406A and the publication (announcement) date of 2015-11-11, it is disclosed that A new type of waste water defluoridation process. The original process and equipment are used to the maximum extent. After the waste acid is vulcanized to remove most of the heavy metal pollutants, it enters the gypsum process for pre-neutralization. The F content of the gypsum filtrate outlet can be controlled at 60 ~100mg/l or less. Then use calcium carbide slag to neutralize the gypsum filtrate, add flocculant to flocculate, and filter to remove heavy metal pollutants in the wastewater, so that the fluorine concentration in the flocculation filtrate can be controlled below 20-40mg/L. Then add aluminum sulfate solution to complex and adsorb fluoride ions, which can reduce the F concentration in the wastewater to below 5mg/L, and other elements can reach the standard. However, the above-mentioned scheme still has problems such as slow reaction speed and large amount of waste residue in the reaction process; The defluoridation method of the integrated application of electrodialysis and adsorption method is carried out according to the following process: 1. Select a defluoridation agent with an adsorbent capacity greater than 5mg/g and install a mechanical filter, a defluorination column tank, and a precision filter 2. Install electrodialyzer and pre-treatment mechanical filter, precision filter and flow rate Use pipe fittings and stop valves to communicate with the storage tank, and control the fluorine content of the water after defluoridation to 0.0-1.8mg/L; 3. Install the storage tank and mark the scale and water storage capacity on the tank body; 4. Turn on the adsorption method and electric For the dialysis type defluoridation device, the fluorine content of water in one defluorination method is used to calculate the fluorine content of water in another defluorination method, and the flow meter is used to regulate the ratio of the two into the storage tank; 5. Deployment: such as 1 : 1 The fluorine content in water by electrodialysis is 0.2 mg/L, and the fluorine content in water by adsorption is 1.6 mg/L, and so on. The above-mentioned integrated fluoride removal method doubles the water resource utilization rate compared with the single fluoride removal method, but it still requires the fluorine content in the water to be 0.0-1.8 mg/L before electrodialysis, which has strict requirements on water quality, and the raw water needs to be pre-treated. treatment, which increases the treatment cost, and the quality of effluent water cannot meet the requirements of ultra-pure water in the electronics industry.

In addition, the current photovoltaic industry, integrated circuit industry and semiconductor industry require a large amount of high-quality ultrapure water for washing. For example, in the process flow of semiconductor device preparation, according to statistics, the washing process of silicon wafers accounts for 17% of the total process steps. as much. In the electronics industry, tap water is often used as raw water to prepare ultrapure water. The huge demand for ultrapure water makes tap water a non-negligible part of the cost of ultrapure water preparation. Therefore, if the wastewater in the electronics industry can meet the raw water quality requirements of the ultrapure water preparation system after treatment, the cost of ultrapure water preparation can be greatly reduced, thereby reducing the cost of electronic product production.

According to ASTM D5127-13 (2018), Ultrapure Water Quality Requirements for Electronics and Semiconductor Industry, the fluorine content in water for microelectronics production equipment with a line width between 0.5 and 1.0um should be controlled within 0.1ug/L. This is because the presence of fluorine in ultrapure water may affect the quality of the produced product. For example, in the wafer manufacturing process, fluorine is the main pollutant that causes the failure of the keypad. Fluorine pollution will cause corrosion and defects of the aluminum keypad, thereby Affects the quality of manufactured microchips. Another example is that in the process of manufacturing integrated circuits (ICs), ultrapure water is mainly used to remove surface pollutants (particles) and to process circuit boards after wet pickling. The circuit boards will go through 50 cycles of ultrapure water processing, so ionic impurities in the water can negatively affect the quality of the final product. The silicon plate atoms located on the surface of the circuit board have a large number of unsaturated bonds, so they have very high chemical activity and corresponding adsorption properties, and the inorganic pollutants adsorbed on the surface will increase the defects of the deposited layer, and the defects can diffuse into the bulk , resulting in structural defects. Ion contamination can cause closure between conductors, corrode conductors, and distort topological patterns of the IP layer. Therefore, when reusing the effluent from the electronic wastewater treatment process, it should be ensured that the ultrapure water preparation system can have a certain removal effect on the fluorine in the reused water, so that it can meet the ultrapure water quality requirements of the electronics and semiconductor industries. However, the concentration of fluoride ions in the effluent of commonly used precipitation methods, adsorption methods, electrochemical methods, and membrane treatment methods is usually at the mg/L level, which cannot meet the requirements of ultra-pure water in the electronics industry.

Therefore, it is imperative to develop a practical method for removing fluoride.

Contents of the invention

1. The problem to be solved

In view of the above problems, the present invention provides a treatment method for fluorine-containing recycled water, which combines chemical precipitation, flocculation precipitation and EDI water treatment technology, and the fluorine content of the effluent is extremely low, which can reach the standard of ultra-pure water, and the fluorine removal efficiency is high , High waste water reuse rate, low operating cost.

2. Technical solution

In order to solve the above problems, the technical scheme adopted in the present invention is as follows:

A treatment method for fluorine-containing reused water, comprising the steps of:

(1) Pretreatment: Introduce excess calcium hydroxide and calcium chloride solution into fluorine-containing wastewater with a pH value of 8 to 9 to generate calcium fluoride and adjust the pH value of the influent;

What needs to be explained here is that the water quality (mainly pH and fluorine content) of the wastewater needs to be tested in advance. The "fluorine-containing wastewater with a pH value of 8-9" can be the original wastewater without acid-base adjustment, or it can be It is waste water adjusted by acid and alkali according to needs; in addition, according to the detected fluorine content, excessive calcium ions are introduced into the water body. The "excess" mentioned here refers to the fluorine contained in the waste water The amount of ions is more than the theoretical requirement for complete precipitation of fluoride ions.

(2) adding a coagulant to the pretreated waste water, then adjusting the pH value of the waste water to 6-7, and then introducing the flocculant;

(3) Filtration, the waste water after the flocculation and precipitation gets supernatant, filters (utilizes cartridge filter to remove solid impurity in waste water), then, utilizes reverse osmosis membrane filtration to carry out reverse osmosis treatment;

(4) TOC degradation and ultraviolet sterilization, (using TOC degrader) TOC degradation treatment of reverse osmosis membrane effluent, and then treated by ultraviolet irradiation;

(5) EDI treatment, the waste water is treated by an electrodeionization system, the resin filled in the electrodeionization system is a porous polystyrene resin (HZO-201) loaded with nano hydrated zirconia;

(6) TOC degradation and ultraviolet sterilization, (using TOC degrader, the degrader uses 185nm ultraviolet light) to carry out TOC degradation treatment on EDI effluent, and then sterilize by ultraviolet irradiation;

(7) Precision filter: The water treated by ultraviolet radiation is filtered with a precision filter (PP melt-blown filter core, filter core precision 5um).

Preferably, in step (1), the described fluorine content in waste water is a benchmark, and the dosage concentration of calcium hydroxide is The dosing mass concentration of calcium chloride is The unit of the mass concentration is mg/L, and the introduced calcium hydroxide and calcium chloride will undergo chemical precipitation reaction with fluoride ions to generate calcium fluoride.

Preferably, in step (2), the coagulant is PAC, based on the mass concentration of fluorine in the water body, and its dosage is C _PAC = _4CF ^- ; the flocculant is PAM, based on the fluorine concentration in the water body The mass concentration of the product is used as the benchmark, and the dosage is C _PAM = _4CF ^- . In the step, the flocculant is added first, and then the pH is adjusted, so that the CaF ₂ generated in the step (1) can be precipitated and transformed into larger particles, and then the flocculant is introduced to enhance the precipitation effect.

Preferably, in step (4), the ultraviolet irradiation is specifically to use a UV-254nm ultraviolet sterilizer to treat the effluent after TOC degradation.

In step (3), the supernatant of the flocculation precipitation is initially filtered to remove solid impurities in the wastewater; then the wastewater is treated with a reverse osmosis membrane to remove sodium, calcium, magnesium, chloride, nitrate, Soluble substances such as carbonates; in step (4), process the effluent from the reverse osmosis membrane with a TOC degrader, and generate hydroxyl radicals in the water through high-dose UV-185nm ultraviolet light catalysis, which will affect the organic matter, ozone, and Chlorine and chloramines are oxidatively degraded, thereby reducing the TOC content in the water; using a UV-254nm ultraviolet sterilizer, the TOC degraded water can be further disinfected.

Preferably, in step (5), the EDI treatment is specifically to firstly carry out primary EDI treatment to the effluent of step (4) (the resin in the electrodeionization system utilized by it is a gel-type strong resin), the purpose It is to remove the dissolved gas, boron and silicon dioxide in the water body; and then carry out secondary EDI treatment. The resin filled in the electrodeionization system of the secondary EDI treatment is porous polyphenylene oxide loaded with nano-hydration zirconia. Vinyl resin, the purpose is to further improve the removal rate of fluorine. Here, the porous polystyrene resin loaded with nanometer hydrated zirconia (the described porous polystyrene resin loaded with nanometer hydrated zirconia is a reference, Xu Jingsheng, Porous polystyrene resin loaded nanometer hydrated zirconia Preparation and its defluorination performance, HZO-201 in 2014-05-28).

Preferably, in step (5), during the secondary EDI treatment, the fluoride ion concentration in the influent is 0-5 mg/L. In addition, other specific treatment parameters are as follows: the pH value of the influent water is 5.8-8.0; the temperature is 5-35°C; the pressure of the influent water is 1.5-4kg/cm ² .

Preferably, in step (6), the TOC degradation and ultraviolet sterilizing processes are the same as step (4).

Preferably, in step (7), the filtration accuracy of the precision filter is 5um.

An ultrapure water is prepared by using the above-mentioned treatment method for fluorine-containing recycled water.

The application of the above-mentioned ultrapure water is applied in the process of manufacturing integrated circuits to clean circuit boards.

3. Beneficial effect

Compared with the prior art, the beneficial effects of the present invention are:

(1) The present invention provides a treatment method for fluorine-containing reused water. Utilizing this technology to treat fluorine-containing wastewater (especially fluorine-containing wastewater in the electronics industry) has the following advantages: one, the removal rate of fluoride ions in the wastewater is high , can reach the level of ultrapure water; secondly, the removal efficiency of fluoride ions is high; thirdly, it can greatly improve the recycling rate of wastewater and significantly reduce the operating cost of ultrapure water preparation system;

(2) The invention provides a kind of processing method of fluorine-containing reused water, at first, carry out flocculation sedimentation, filter treatment to waste water, can remove CaF ₂ solid impurities in the precipitated particle and other waste water, prevent the clogging of permeable membrane in the next step; Then, use the reverse osmosis membrane to treat the wastewater, remove sodium, calcium, magnesium, chloride, nitrate, carbonate and other soluble substances, reduce the hardness of the water body, and prevent the calcium and magnesium scale from affecting the subsequent treatment steps; EDI technology then treats the effluent to remove dissolved gases, boron and silica; the wastewater is then treated with a secondary EDI system filled with porous polystyrene resin loaded with nano-hydrated zirconia, further reducing the The fluorine content in the water body; finally, the water body is subjected to secondary degradation of TOC, ultraviolet sterilization, that is, precision filtration, so that the quality of the effluent reaches the level of ultra-pure water;

(3) In the existing ultrapure water preparation system, RO/EDI integrated technology is usually used to remove impurity ions in raw water, but the above-mentioned technology treats mostly tap water. However, in this patent application document, it is electronic waste water containing fluoride ions. Due to the small radius of the fluoride ions contained therein, the fluoride ions in the effluent of the reverse osmosis membrane usually have a high content. When the principle of ion exchange removes impurity ions in wastewater, because the fluoride ions are sorted relatively late, the removal effect of fluoride ions will be affected by anions such as sulfate, nitrate, chromate, bromide, cyanide, and chloride ions, while electrons Wastewater usually contains a large amount of anions, so when electronic waste water is reused as ultrapure water to prepare system raw water, the effect of EDI technology for defluorination is not ideal;

Based on this, the present invention provides a treatment method for fluorine-containing reused water, which is a combination of primary EDI treatment and secondary EDI treatment for water bodies to treat fluorine-containing wastewater; in the secondary EDI system for treatment, the The resin used is a porous polystyrene resin loaded with nano-hydration zirconia, which has the following advantages: First, the polarization in the interfacial diffusion layer where the ion-exchange resin, ion-exchange membrane and water are in contact dissociates water into hydrogen ions And hydroxide ions, in addition to carrying current, they are also used for the regeneration of the resin, the nano hydrated zirconia loaded on the resin enhances the conductivity of the resin, so more hydrogen ions and hydroxide ions can be used to regenerate the resin , to ensure the regeneration rate of the resin; second, in the conventional EDI technology, water dissociates under the action of an electric field to generate hydrogen ions and hydroxide ions, some of these ions are dissociated for resin regeneration, and the other part is used to bear the current. The porous polystyrene resin loaded with nano hydrated zirconia used in this technology is loaded with nano hydrated zirconia to enhance the conductivity of the resin, so that more hydrogen ions and hydroxide ions generated by water electrolysis can be used for resin regeneration , thereby improving the removal effect of ion exchange resins for impurity ions, and enhancing the defluorination effect of fluorine-removing resins;

(4) For the existing defluorination technology of porous polystyrene resin loaded with nano-hydrated zirconia, after a period of defluorination during use, it is necessary to use a desorbent to desorb the fluorine-removing resin, and the desorption and regeneration of the resin will Greatly increase the operating cost of resin defluorination. In order to improve the feasibility of the industrial promotion of this specific fluoride removal resin, this technology combines electrodialysis with ion exchange resin to realize continuous regeneration of the new type of fluoride removal resin, which saves the cost of desorption and regeneration during the use of the resin. It greatly reduces the operating cost of the specific fluoride removal resin for fluorine removal.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments.

Example 1

In this embodiment, 2L of fluorine-containing wastewater from a microelectronics manufacturing plant is taken with the fluorine-containing wastewater in the electronics industry. The raw water pH value is 2.84, the COD concentration is 86mg/L, and the fluoride ion concentration is 364mg/L. Electrode method is used to measure the fluoride ion concentration in the water, and the lower limit of detection is 15.1 μg/L), and the waste water is processed by the processing method of the present invention, and the specific steps are as follows:

(1) Adjust the pH value of the wastewater to 8-9, introduce excess calcium hydroxide and calcium chloride solution into it, and make it undergo chemical precipitation reaction to generate calcium fluoride.

(2) Flocculation and precipitation, step (1) introduce the coagulant PAC into the wastewater after the chemical precipitation reaction occurs, so that the fine precipitation produces larger particles, and then adjust the pH of the wastewater to 6-7, and then introduce the flocculant PAM to enhance the precipitation Effect.

(3) Take the supernatant in step (2), and after utilizing the cylindrical filter to remove solid impurities in the waste water, pass the waste water through the reverse osmosis membrane to remove the solubility of sodium, calcium, magnesium, chloride, nitrate, carbonate, etc. substance.

(4) TOC degradation and ultraviolet sterilization, (use TOC degrader) to perform TOC degradation treatment on the effluent of reverse osmosis membrane, and then irradiate with ultraviolet light, it can be catalyzed by high-dose UV-185nm ultraviolet light to generate hydroxyl radicals in water, Oxidative degradation of organic matter in water to reduce TOC content in water;

Use UV-254nm ultraviolet sterilizer to treat the effluent after TOC degradation.

(5) EDI treatment, effluent in step (4), waste water is processed by electrodeionization system, the resin filled in the described electrodeionization system is the porous polystyrene resin that is loaded with nanometer hydrated zirconia; Its specific The treatment parameters are as follows: the pH value of the influent water is 5.8-8.0; the temperature is 5-35° C.; the influent water pressure is 1.5-4 kg/cm ² .

The water quality of wastewater after EDI treatment is shown in Table 1:

Table 1 Wastewater quality after EDI treatment

(6) TOC degradation and ultraviolet sterilization, (use TOC degrader) to carry out TOC degradation treatment on EDI effluent, and then sterilize by UV-254nm ultraviolet sterilizer.

(7) Precision filter: The water treated by ultraviolet radiation is filtered with a precision filter (PP melt-blown filter core, filter core precision 5um).

The total effluent quality is shown in Table 2:

Table 2 Total effluent water quality

"—" in the table indicates that the concentration of fluoride ion in the water body is lower than the detection limit of 15.1 μg/L.

As can be seen from the data in Table 1 and Table 2, after being treated by the newly developed fluoride removal technology of the present invention, the removal rate of fluoride ions in the wastewater reaches 95%, and the wastewater is further passed through the TOC degrader, polished mixed bed, and ultraviolet sterilizer. After the advanced treatment of the precision filter, the presence of fluoride ions was not detected by the direct ion selective electrode method, and the removal rate of fluoride ions in the whole process reached more than 99%, and the quality of the effluent water met the requirements for ultra-pure water in the electronics industry.

Example 2

In this embodiment, 2L of fluorine-containing wastewater from a microelectronics manufacturing plant is taken with the fluorine-containing wastewater in the electronics industry. The raw water pH value is 2.84, the COD concentration is 86mg/L, and the fluoride ion concentration is 364mg/L. Electrode method is used to measure the fluoride ion concentration in the water, and the lower limit of detection is 15.1 μg/L), and the waste water is processed by the processing method of the present invention, and the specific steps are as follows:

(1) Adjust the pH value of waste water to 8-9, introduce excessive calcium hydroxide and calcium chloride solution therein, make it produce calcium fluoride by chemical precipitation reaction; take the mass concentration of fluorine in the water body as a benchmark, said hydroxide The dosage of calcium is The dosage of calcium chloride is

(2) Flocculation and precipitation, step (1) introduce the coagulant PAC into the wastewater after the chemical precipitation reaction occurs, so that the fine precipitation produces larger particles, and then adjust the pH of the wastewater to 6-7, and then introduce the flocculant PAM to enhance the precipitation effect; the coagulant is PAC, based on the mass concentration of fluorine in the water body, its dosage is C _PAC = _4CF ^- ; the flocculant is PAM, based on the mass concentration of fluorine in the water body, its The dosage is C _PAM = 4C _F ^- . After this step of treatment, the pH of the effluent is 7.96, the COD is 41mg/L, and the fluoride ion concentration is 3.2mg/L.

(3) Take the supernatant in step (2), and after utilizing the cylindrical filter to remove solid impurities in the waste water, pass the waste water through the reverse osmosis membrane to remove the solubility of sodium, calcium, magnesium, chloride, nitrate, carbonate, etc. substance.

(4) Use the TOC degrader (UV-185nm low-pressure high-energy ultraviolet technology) to treat the effluent from the reverse osmosis membrane, and then combine it with the UV-254nm ultraviolet sterilizer to catalyze the high-dose UV-185nm ultraviolet light to generate free hydroxyl groups in the water base, to oxidize and degrade the organic matter in the water to reduce the TOC content in the water;

Then it is sterilized by UV-254nm ultraviolet sterilizer.

(5) EDI treatment, to the effluent in step (4), first utilize the electrodeionization system that is filled with gel-type strong resin to carry out one-level EDI treatment to waste water; Its specific treatment parameters are as follows: the influent pH value is 5.8- 8.0; temperature is 5-35°C; water inlet pressure is 1.5-4kg/cm ² ;

Then use the electrodeionization system filled with porous polystyrene resin loaded with nano-hydrated zirconia to carry out secondary EDI treatment on the wastewater. The specific treatment parameters are as follows: the pH value of the influent is 5.8-8.0; the temperature is 5-35 ° C ; The water inlet pressure is 1.5-4kg/cm ² . The quality of wastewater after EDI treatment is shown in Table 3:

Table 3 Wastewater quality after EDI treatment

(6) Disinfect the wastewater treated by EDI through a secondary TOC degrader, a polished mixed bed, and a UV-254nm ultraviolet sterilizer.

(7) Precision filter: The water treated by ultraviolet radiation is filtered with a precision filter (PP melt-blown filter element, filter element precision 5um) to prepare electronic grade ultrapure water with high resistivity. The quality of the effluent water is shown in Table 4 Shown:

Table 4 Total effluent water quality

"—" in the table indicates that the concentration of fluoride ion in the water body is lower than the detection limit of 15.1 μg/L.

As can be seen from the data in Table 3 and Table 4, after being treated by the newly developed fluoride removal technology of the present invention, the fluoride ion removal rate in the wastewater reaches 95%, and the wastewater is further passed through the TOC degrader, polished mixed bed, and ultraviolet sterilizer. After the advanced treatment of 0.1um cartridge filter and ultrafiltration module, the existence of fluoride ion was not detected by direct ion selective electrode method, and the removal rate of fluoride ion in the whole process reached over 99%, and the effluent quality met the requirements of ultra-pure electronics industry Water water requirements.

Example 3

In this embodiment, 2L of fluorine-containing wastewater from a microelectronics manufacturing plant is taken with the fluorine-containing wastewater in the electronics industry. The raw water pH value is 2.84, the COD concentration is 86mg/L, and the fluoride ion concentration is 364mg/L. Electrode method is used to measure the fluoride ion concentration in the water, and the lower limit of detection is 15.1 μg/L), and the waste water is processed by the processing method of the present invention, and the specific steps are as follows:

(1) Adjust the pH value of waste water to 8-9, introduce excessive calcium hydroxide and calcium chloride solution therein, make it produce calcium fluoride by chemical precipitation reaction; take the mass concentration of fluorine in the water body as a benchmark, said hydroxide The dosage of calcium is The dosage of calcium chloride is

(2) Flocculation and precipitation, step (1) introduce the coagulant PAC into the wastewater after the chemical precipitation reaction occurs, so that the fine precipitation produces larger particles, and then adjust the pH of the wastewater to 6-7, and then introduce the flocculant PAM to enhance the precipitation Effect.

(3) Take the supernatant in step (2), and after utilizing the cylindrical filter to remove solid impurities in the waste water, pass the waste water through the reverse osmosis membrane to remove the solubility of sodium, calcium, magnesium, chloride, nitrate, carbonate, etc. substance.

(4) TOC degradation and ultraviolet sterilization, (use TOC degrader) to perform TOC degradation treatment on the effluent of reverse osmosis membrane, and then irradiate with ultraviolet light, it can be catalyzed by high-dose UV-185nm ultraviolet light to generate hydroxyl radicals in water, Oxidative degradation of organic matter in water to reduce TOC content in water;

Use UV-254nm ultraviolet sterilizer to treat the effluent after TOC degradation.

(5) EDI treatment, effluent in step (4), waste water is processed by electrodeionization system, the resin filled in the described electrodeionization system is the porous polystyrene resin that is loaded with nanometer hydrated zirconia; Its specific The treatment parameters are as follows: the pH value of the influent water is 5.8-8.0; the temperature is 5-35° C.; the influent water pressure is 1.5-4 kg/cm ² .

(6) TOC degradation and ultraviolet sterilization, (use TOC degrader) to carry out TOC degradation treatment on EDI effluent, and then sterilize by UV-254nm ultraviolet sterilizer.

(7) Precision filter: The water treated by ultraviolet radiation is filtered with a precision filter (PP melt-blown filter core, filter core precision 5um).

After treatment, the presence of fluoride ions was not detected by the direct ion selective electrode method, the removal rate of fluoride ions in the whole process reached over 95%, and the effluent quality met the requirements for ultra-pure water in the electronics industry.

Example 4

In this embodiment, 2L of fluorine-containing wastewater from a microelectronics manufacturing plant is taken with the fluorine-containing wastewater in the electronics industry. The raw water pH value is 2.84, the COD concentration is 86mg/L, and the fluoride ion concentration is 364mg/L. Electrode method is used to measure the fluoride ion concentration in the water, and the lower limit of detection is 15.1 μg/L), and the waste water is processed by the processing method of the present invention, and the specific steps are as follows:

(1) Adjust the pH value of the wastewater to 8-9, introduce excess calcium hydroxide and calcium chloride solution into it, and make it undergo chemical precipitation reaction to generate calcium fluoride.

(2) Flocculation and precipitation, step (1) introduce the coagulant PAC into the wastewater after the chemical precipitation reaction occurs, so that the fine precipitation produces larger particles, and then adjust the pH of the wastewater to 6-7, and then introduce the flocculant PAM to enhance the precipitation effect; the coagulant is PAC, based on the mass concentration of fluorine in the water body, its dosage is C _PAC = _4CF ^- ; the flocculant is PAM, based on the mass concentration of fluorine in the water body, its The dosage is C _PAM = 4C _F ^- .

(3) Take the supernatant in step (2), and after utilizing the cylindrical filter to remove solid impurities in the waste water, pass the waste water through the reverse osmosis membrane to remove the solubility of sodium, calcium, magnesium, chloride, nitrate, carbonate, etc. substance.

(4) TOC degradation and ultraviolet sterilization, (use TOC degrader) to perform TOC degradation treatment on the effluent of reverse osmosis membrane, and then irradiate with ultraviolet light, it can be catalyzed by high-dose UV-185nm ultraviolet light to generate hydroxyl radicals in water, Oxidative degradation of organic matter in water to reduce TOC content in water;

Use UV-254nm ultraviolet sterilizer to treat the effluent after TOC degradation.

(5) EDI treatment, effluent in step (4), waste water is processed by electrodeionization system, the resin filled in the described electrodeionization system is the porous polystyrene resin that is loaded with nanometer hydrated zirconia; Its specific The treatment parameters are as follows: the pH value of the influent water is 5.8-8.0; the temperature is 5-35° C.; the influent water pressure is 1.5-4 kg/cm ² .

(6) TOC degradation and ultraviolet sterilization, (use TOC degrader) to carry out TOC degradation treatment on EDI effluent, and then sterilize by UV-254nm ultraviolet sterilizer.

(7) Precision filter: The water treated by ultraviolet radiation is filtered with a precision filter (PP melt-blown filter core, filter core precision 5um).

After treatment, the presence of fluoride ions was not detected by the direct ion selective electrode method, the removal rate of fluoride ions in the whole process reached over 95%, and the effluent quality met the requirements for ultra-pure water in the electronics industry.

Comparative example 1

The difference between this comparative example and embodiment 2 basically is:

The electrodeionization system of the first-level EDI treatment in step (5) is the same as that of the second-level EDI treatment (that is, the filled resins are all gel-type strong resins)

The water quality of wastewater after EDI treatment is shown in Table 5:

Table 5 Wastewater quality after EDI treatment

Table 6 Total effluent water quality

From the data in Table 5 and Table 6, it can be seen that after the reuse of fluorine-containing wastewater is treated by conventional EDI technology, the removal rate of fluoride ions in the wastewater is 23%, and the wastewater is further passed through the TOC degrader, polished mixed bed, and ultraviolet sterilizer , After advanced treatment of 0.1um cartridge filters and ultrafiltration components, the quality of effluent water does not meet the requirements for ultra-pure water in the electronics industry. Therefore, if the fluorine-containing wastewater after preliminary defluoridation treatment is reused as the raw water of the ultrapure water system, the ultrapure water preparation system composed of conventional EDI devices cannot produce ultrapure water that meets the production needs of the industry, so Further improvement of the ultrapure water preparation system is required for the recycling of fluorinated wastewater.

Comparative example 2

The difference between this comparative example and embodiment 2 basically is:

In the step (5), the EDI treatment technology is replaced by an electrodialysis treatment method.

The basic conditions are as follows: adopt the electrodialyzer with punching mode diaphragm 400*800mm, 150 pairs of membranes, three-stage three-stage assembly;

Use polyethylene heterogeneous film.

Table 7 Water quality before and after electrodialysis treatment

Table 8 Total effluent water quality

From the data in Table 7 and Table 8, it can be seen that after the reuse of fluorine-containing wastewater is treated by conventional electrodialysis technology, the removal rate of fluoride ions in the wastewater is only 14%. After the advanced treatment of ultraviolet sterilizer, 0.1um cartridge filter and ultrafiltration module, the content of fluoride ion is still high, and the quality of effluent water does not meet the requirements of ultrapure water in the electronics industry. Therefore, if the fluorine-containing wastewater after the preliminary defluorination treatment is reused as the raw water of the ultrapure water system, the ultrapure water that meets the production needs of the industry cannot be prepared using the ultrapure water preparation system composed of conventional electrodialysis devices.

Claims (9)

1. a kind of processing method of fluorine-containing recycle-water, which is characterized in that comprise the following steps:

(1) it pre-processes, excess calcium hydroxide and calcium chloride is introduced in the fluoride waste for being 8~9 to pH value；

(2) coagulant is added into pretreated water body for flocculation sedimentation, and then, the pH value for adjusting waste water is 6-7, is re-introduced into Flocculant；

(3) it filters, the waste water after flocculation sedimentation takes supernatant, filters, and then, carries out reverse osmosis treatment using reverse osmosis membrane；

(4) TOC degradation and ultraviolet sterilization are discharged reverse osmosis membrane and carry out TOC degradation and the processing of ultraviolet light irradiation-sterilize；

(5) EDI is handled, and by electrodeionization system, to ultraviolet light irradiation-sterilize, treated that water body is handled, and the electricity is gone The resin filled in ion system, which is negative, is loaded with the expanded polystyrene resin of nano hydrated zirconium oxide；

(6) TOC degradation and ultraviolet sterilization, are discharged EDI and carry out TOC degradation treatment, then handle through ultraviolet light irradiation-sterilize；

(7) secondary filter, water body is filtered using accurate filter after ultraviolet treatment with irradiation.

2. the processing method of fluorine-containing recycle-water according to claim 1, which is characterized in that in step (1), with fluorine in water body On the basis of mass concentration, the dosage of the calcium hydroxide isThe dosage of calcium chloride is

3. the processing method of fluorine-containing recycle-water according to claim 1, which is characterized in that in step (2), the coagulant For PAC, on the basis of the mass concentration of fluorine in water body, dosage C_PAC=4C_F ^-；The flocculant is PAM, in water body On the basis of the mass concentration of fluorine, dosage C_PAM=4C_F ^-。

4. the processing method of fluorine-containing recycle-water according to claim 1, which is characterized in that in step (4), the ultraviolet light Irradiation is specifically, handle the water outlet after TOC degradation using UV-254nm ultraviolet sterilizer.

5. the processing method of fluorine-containing recycle-water according to claim 1, which is characterized in that in step (5), at the EDI Reason carries out level-one EDI processing specifically, being first discharged to step (4), then carries out second level EDI processing, the second level EDI processing again Electrodeionization system in the resin filled be negative and be loaded with the expanded polystyrene resin of nano hydrated zirconium oxide.

6. the processing method of fluorine-containing recycle-water according to claim 5, which is characterized in that in step (5), the second level The fluorinion concentration upper limit is 5mg/L in the water inlet of EDI processing.

7. the processing method of fluorine-containing recycle-water according to claim 1, which is characterized in that in step (7), accurate filter Filtering accuracy be 5um.

8. a kind of ultrapure water, which is characterized in that prepared using the processing method of the fluorine-containing recycle-water as claimed in claim 1 to 7 It obtains.

9. the application of ultrapure water as claimed in claim 8, which is characterized in that be applied to the technique of manufacture integrated circuit In, the cleaning to circuit board.