CN110451704B - Method for treating fluorine-containing reuse water - Google Patents

Method for treating fluorine-containing reuse water Download PDF

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CN110451704B
CN110451704B CN201910815633.0A CN201910815633A CN110451704B CN 110451704 B CN110451704 B CN 110451704B CN 201910815633 A CN201910815633 A CN 201910815633A CN 110451704 B CN110451704 B CN 110451704B
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water
fluorine
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wastewater
treating
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CN110451704A (en
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张炜铭
贾如雪
张孝林
张延扬
潘丙才
吕路
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Jiangsu Nju Environmental Technology Co ltd
Nanjing University
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Jiangsu Nju Environmental Technology Co ltd
Nanjing University
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    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00Multistage treatment of water, waste water, or sewage
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/001Processes for the treatment of water whereby the filtration technique is of importance
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/30Treatment of water, waste water, or sewage by irradiation
    • C02F1/32Treatment of water, waste water, or sewage by irradiation with ultra-violet light
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/42Treatment of water, waste water, or sewage by ion-exchange
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/44Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/441Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/46Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/469Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/52Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/5236Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/52Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/54Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
    • C02F1/56Macromolecular compounds
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/72Treatment of water, waste water, or sewage by oxidation
    • C02F1/722Oxidation by peroxides
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00Nature of the contaminant
    • C02F2101/10Inorganic compounds
    • C02F2101/12Halogens or halogen-containing compounds
    • C02F2101/14Fluorine or fluorine-containing compounds
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2301/00General aspects of water treatment
    • C02F2301/08Multistage treatments, e.g. repetition of the same process step under different conditions

Abstract

The invention discloses a method for treating fluorine-containing reuse water, which comprises the following specific steps: (1) pre-treating; (2) flocculating and precipitating; (3) filtering, namely filtering by a reverse osmosis membrane; (4) TOC degradation and ultraviolet sterilization; (5) EDI processing; (6) TOC degradation and ultraviolet sterilization; (7) performing precision filtration; the invention has the advantages that the effluent quality can reach the ultrapure water standard, and the invention has high defluorination efficiency, high wastewater reuse rate and low operation cost.

Description

Method for treating fluorine-containing reuse water
Technical Field
The invention belongs to the field of wastewater treatment, and particularly relates to a method for treating fluorine-containing reuse water in the electronic industry.
Background
Along with the rapid development of electronic products in recent years, the discharge amount of waste water in the electronic industry is increasing day by day, and in addition, as the preparation process in the electronic industry is becoming more and more complex, the treatment difficulty of the electronic waste water is increasing. At present, the main sources of electronic wastewater comprise procedures of polishing, chemical etching, black/brown oxidation, deburring, glue residue removal, through hole plating, tin plating, copper plating, tin stripping, solder mask, development, molding cleaning and the like, so that the electronic wastewater contains various substances which need to be treated and have negative effects on the environment, wherein the substances comprise fluorine ions. Taking semiconductor industry units such as photovoltaic cell manufacturing, electronic factories and the like as examples, a large amount of hydrofluoric acid is used for wafer etching and quartz cleaning, wherein etching liquid used in a wet etching process contains hydrofluoric acid and ammonium fluoride, fluorine ions enter electronic wastewater along with pure water in a cleaning link, and the concentration of fluorine in generated fluorine-containing acidic wastewater can reach more than 1000 mg/L. Fluorine poses a great threat to the health of people and animals and causes death of people in severe cases, so that the direct discharge of the fluorine-containing wastewater can pose a great threat to the environment, in order to avoid pollution of underground water, soil and surface water, the electronic wastewater needs to be subjected to defluorination treatment before reaching the discharge limit, such as the limit of fluoride discharge in the public sewage treatment system specified by the current semiconductor industry pollutant discharge standard (DB 31/445) 2006 in Shanghai, the limit of fluoride discharge in the public sewage treatment system specified by the current comprehensive water pollutant discharge standard (DB11/307 2013) in Beijing is 10mg/L, and the concentration limit of fluoride in drinking water is 1.5mg/L according to the recommendation of the world health organization.
The existing treatment methods of fluorine-containing wastewater mainly comprise a precipitation method, an adsorption method, an electrochemical method and a membrane treatment method. The precipitation method is mainly a process of adding substances (lime, neutral calcium salt, aluminum salt, iron salt, PAM and the like) which have the coagulation ability or generate precipitation with fluoride into the wastewater to form a large amount of colloid substances or precipitation, coagulating or precipitating the fluoride along with the colloid substances or precipitation, and then filtering to remove fluorine ions from the water; the method has the advantages of simple and convenient operation, low cost, large wastewater treatment amount, effluent basically reaching the wastewater discharge standard (10-20mg/L), suitability for drinking water treatment, suitability for industrial application, low reaction speed, large amount of waste residues in the reaction process, and difficulty in treating the effluent alone lower than 10 mg/L. The adsorption method is a means for removing fluorine by adding a specific adsorbent into wastewater, and the basic process comprises the following four steps: (1) solute molecules diffuse from the bulk of the solution through the boundary layer on the surface of the adsorbent to the outer surface of the adsorbent, referred to as out-diffusion; (2) solute molecules diffuse through pores and migrate from the outer surface of the adsorbent to the interior of the adsorbent pores, referred to as internal diffusion; (3) fluorine ions diffuse along the surface of the pore surface; (4) the fluorine ions are adsorbed on the pore surfaces. Typical adsorbents are active metal oxides, zeolites and resins; however, the regeneration of the active metal oxide is complex, the active metal oxide needs to be burned at the temperature of 420-1000 ℃, and the zeolite is used as a defluorination adsorbent, which has lower adsorption capacity, large dosage and long adsorption time, so the zeolite is only suitable for the treatment of fluorine-containing water in rural areas and is not suitable for the use of large-scale treatment equipment; in the process of removing fluorine by the ion exchange resin, the fluorine removal effect is influenced by other mineral substances in the wastewater, so that the quality of effluent is reduced; and the resin is easily contaminated by other impurities, resulting in deterioration of the defluorination effect. The electrodialysis is to realize the purposes of concentration, desalination, refining and purification of the solution by utilizing the selective permeability of the ion exchange membrane and the directional migration of charged ions through the ion exchange membrane to separate the charged ions from the aqueous solution and other uncharged components under the action of a direct current electric field. The device is simple, the operation is easy, the operation is stable, the water can be continuously produced, the automatic control is easy to realize, and the like, the fluorine removal is clean and thorough, the water outlet quality is good, the automatic operation can be realized, and the management is easy; the method is suitable for high-fluorine brackish water with the salt content of 1-5g/L and the fluorine content of less than 5mg/L of raw water, and is suitable for concentrated drinking water defluorination engineering in northwest and Shandong regions of China; however, the requirement on water quality is strict, and raw water needs to be pretreated; the treatment cost is high (about 6 yuan/ton water), and the equipment investment is large; other beneficial components are removed, and the fluorine removal efficiency needs to be improved; the technical aspects of the method include membrane polarization scaling, and the type and the service life of the membrane are yet to be researched; the membrane treatment method is to use a membrane made of organic polymer or inorganic material to permeate solute or solvent in solution on one side to the other side by using the concentration difference of the solution on the two sides of the membrane so as to achieve the purpose of separating the solute from the solvent. The membrane separation has the advantage of good separation effect. However, the membrane separation technology has the defects of limitation, pretreatment of the solution, low treatment capacity and the like.
Based on the factors, when the fluorine-containing wastewater is treated, a combined process begins to appear, for example, in the Chinese invention patent application document with the publication (announcement) number of CN105036406A and the publication (announcement) date of 2015-11-11, a novel wastewater fluorine removal process is disclosed, the original process and equipment are utilized to the maximum extent, waste acid is subjected to a vulcanization process to remove most heavy metal pollutants, the waste acid enters a gypsum process to be pre-neutralized, and the concentration F of the gypsum filtrate in the buccal cavity can be controlled to be below 60-100 mg/l. And then, neutralizing the gypsum filtrate by using carbide slag, adding a flocculating agent for flocculation, and filtering to remove heavy metal pollutants in the wastewater, wherein the fluorine concentration in the flocculated filtrate can be controlled below 20-40 mg/L. Then adding aluminum sulfate solution to complex and adsorb fluoride ions, so that the concentration of F in the wastewater can be reduced to below 5mg/L, and other elements reach the standard. However, the scheme still has the problems of low reaction speed, large amount of waste residues in the reaction process and the like; as another example, chinese patent application publication No. CN101121554A, published as 2008-02-13, discloses a method for removing fluorine by integrating an electrodialysis method and an adsorption method, which is performed according to the following steps: 1. selecting a defluorinating agent with the adsorbent capacity of more than 5mg/g, installing a mechanical filter, a defluorination column tank, a precision filter and a flowmeter, communicating the defluorinating agent with a storage tank by using a pipe fitting and a stop valve, and controlling the fluorine content of water after defluorination to be 0.0-1.8 mg/L; 2. installing an electrodialyzer, a mechanical filter for pretreatment, a precision filter and a flowmeter, communicating the electrodialyzer with a storage tank by using a pipe fitting and a stop valve, and controlling the fluorine content of water after fluorine removal to be 0.0-1.8 mg/L; 3. installing a storage tank, and marking scales and water storage capacity on the tank body; 4. starting the adsorption method type and electrodialysis method type fluorine removal devices, calculating the water fluorine content of one fluorine removal method by using the water fluorine content of the other fluorine removal method, and regulating the ratio of the water fluorine content and the water fluorine content of the other fluorine removal method into a storage tank by using a flowmeter; 5. blending: for example, the fluorine content in the water is 0.2mg/L by electrodialysis method and 1.6mg/L by adsorption method at a ratio of 1: 1, and so on. The integrated defluorination method has the advantages that the water resource utilization rate is improved by times compared with that of a single defluorination method, but the water content in water is still required to be 0.0-1.8 mg/L before electrodialysis, the water quality requirement is strict, raw water needs to be pretreated, the treatment cost is improved, and the water quality of outlet water cannot meet the requirement of ultrapure water in the electronic industry.
In addition, in the current photovoltaic industry, integrated circuit industry and semiconductor industry, a large amount of ultrapure water with high water quality level is needed for washing, for example, in the process flow of semiconductor device preparation, the silicon wafer washing link accounts for 17% of the total process steps according to statistics. In the electronic industry, tap water is commonly used as raw water to prepare ultrapure water, and the extremely large demand of the ultrapure water makes the water cost of the tap water become a non-negligible part of the ultrapure water preparation cost. Therefore, if the wastewater in the electronic industry can meet the requirement of the ultrapure water preparation system on the quality of raw water, the cost for preparing ultrapure water can be greatly reduced, and the production cost of electronic products can be reduced.
The requirements of the quality of ultrapure water in the electronic and semiconductor industries in ASTM D5127-13(2018) specify that the fluorine content in water for microelectronic production equipment with a line width of 0.5-1.0 um should be controlled within 0.1 ug/L. This is because the presence of fluorine in ultrapure water can affect the quality of the product produced, as during wafer fabrication fluorine is the primary contaminant causing keymat failure, and fluorine contamination can cause corrosion and defects in the aluminum keymat, thereby affecting the quality of the microchip being fabricated. For another example, in a process flow for manufacturing an Integrated Circuit (IC), ultrapure water is mainly used for removing surface contaminants (particles) and treating a circuit board after a wet pickling process, the circuit board is subjected to 50 times of ultrapure water circulation treatment, and thus ionic impurities in water adversely affect the quality of a final product. The silicon plate atoms located on the surface of the circuit board have a large number of unsaturated bonds and therefore have very high chemical activity and corresponding adsorption properties, and the adsorbed inorganic contaminants on the surface will increase the defects of the deposited layer, which can diffuse into the bulk, resulting in structural defects. Ion contamination can cause closure between conductors, corrode conductors, cause distortion of the topological pattern of the IP layer, and the like. Therefore, when the water is discharged from the electronic wastewater treatment process, the ultrapure water preparation system can be ensured to have a certain removal effect on fluorine in the recycled water, so that the ultrapure water meets the water quality requirement of the electronic and semiconductor industry. The concentration of fluorine ions in effluent water of the defluorination process such as the precipitation method, the adsorption method, the electrochemical method, the membrane treatment method and the like which are commonly used at present is often in the mg/L level, and the requirement of ultrapure water in the electronic industry cannot be met.
Therefore, it is imperative to develop a practical defluorination process.
Disclosure of Invention
1. Problems to be solved
Aiming at the problems, the invention provides a method for treating fluorine-containing reuse water, which combines chemical precipitation, flocculation precipitation and EDI water treatment technologies, has extremely low fluorine content in effluent, can reach the standard of ultrapure water, and has high fluorine removal efficiency, high wastewater reuse rate and low operation cost.
2. Technical scheme
In order to solve the problems, the technical scheme adopted by the invention is as follows:
a method for treating fluorine-containing reuse water comprises the following steps:
(1) pretreatment: introducing excessive calcium hydroxide and calcium chloride solution into fluorine-containing wastewater with the pH value of 8-9 to generate calcium fluoride, and adjusting the pH value of inlet water;
it should be noted here that the water quality (mainly pH and fluorine content) of the wastewater needs to be detected in advance, and the "fluorine-containing wastewater with a pH value of 8 to 9" may be original wastewater that has not been adjusted by acid and alkali, or may be wastewater that has been adjusted by acid and alkali as needed; and introducing excessive calcium ions into the water body according to the detected fluorine content, wherein the excessive calcium ions are more than the theoretical requirement for completely precipitating the fluorine ions by taking the fluorine contained in the wastewater as a standard.
(2) Adding a coagulant into the pretreated wastewater, then adjusting the pH value of the wastewater to 6-7, and introducing a flocculant;
(3) filtering, namely taking supernatant from the wastewater after flocculation precipitation, filtering (removing solid impurities in the wastewater by using a cylindrical filter), and then performing reverse osmosis treatment by using reverse osmosis membrane filtration;
(4) TOC degradation and ultraviolet sterilization, wherein TOC degradation treatment is carried out on the effluent of the reverse osmosis membrane (by utilizing a TOC degradation device), and then ultraviolet irradiation treatment is carried out;
(5) EDI treatment, namely treating the wastewater by an electrodeionization system, wherein the resin filled in the electrodeionization system is porous polystyrene resin (HZO-201) loaded with nano hydrous zirconia;
(6) TOC degradation and ultraviolet sterilization, wherein the TOC degradation device is used for carrying out TOC degradation treatment on EDI effluent (185 nm ultraviolet light is adopted by the TOC degradation device and the degradation device), and then the TOC degradation treatment and the ultraviolet irradiation sterilization treatment are carried out;
(7) a precision filter: the water after the ultraviolet irradiation treatment is filtered by a precision filter (PP spray-melting type filter element with the filter element precision of 5 um).
Preferably, in the step (1), the adding mass concentration of the calcium hydroxide is based on the fluorine content in the wastewater The adding mass concentration of the calcium chloride isThe unit of the mass concentration is mg/L, and the introduced calcium hydroxide and calcium chloride can generate chemical precipitation reaction with fluoride ions to generate calcium fluoride.
Preferably, in the step (2), the coagulant is PAC, and the adding amount is C based on the mass concentration of fluorine in the water bodyPAC=4CF -(ii) a The flocculant is PAM, the mass concentration of fluorine in the water body is taken as a reference, and the adding amount is CPAM=4CF -. In the step (1), a flocculating agent is added firstly, and then the pH is adjusted, so that the CaF generated in the step (1)2The precipitation effect may be enhanced by converting the precipitate into larger particles, followed by the introduction of a flocculating agent.
Preferably, in the step (4), the ultraviolet irradiation is specifically to treat the effluent after TOC degradation by using a UV-254nm ultraviolet sterilizer.
In the step (3), the supernatant of the flocculation precipitation is primarily filtered, so as to remove solid impurities in the wastewater; then, treating the wastewater by using a reverse osmosis membrane so as to remove soluble substances such as sodium, calcium, magnesium, chloride, nitrate, carbonate and the like; treating the effluent of the reverse osmosis membrane by using a TOC degradation device in the step (4), catalyzing by high-dose UV-185nm ultraviolet light to generate hydroxyl radicals in water, and oxidizing and degrading organic matters, ozone, chlorine and chloramine in the water, so as to reduce the TOC content in the water; the TOC degraded effluent can be further sterilized by using a UV-254nm ultraviolet sterilizer.
Preferably, in the step (5), the EDI treatment specifically includes first performing a first-stage EDI treatment on the effluent from the step (4) (the resin in the electrodeionization system used in the step is a gel-type strong resin) to remove the gas dissolved in the water body, boron and silicon dioxide; and then carrying out secondary EDI treatment, wherein the resin filled in the electrodeionization system of the secondary EDI treatment is porous polystyrene resin loaded with nano hydrous zirconia, so as to further improve the removal rate of fluorine. The porous polystyrene resin loaded with nano hydrous zirconia described herein (the porous polystyrene resin loaded with nano hydrous zirconia is a reference, and studies on the preparation and defluorination performance of the porous polystyrene resin loaded with nano hydrous zirconia were conducted, HZO-201 in 2014-05-28).
Preferably, in the step (5), the concentration of fluorine ions in the feed water during the secondary EDI treatment is 0-5 mg/L. In addition, other specific processing parameters are as follows: the pH value of inlet water is 5.8-8.0; the temperature is 5-35 ℃; the water inlet pressure is 1.5-4kg/cm2
Preferably, in step (6), the TOC degradation and UV sterilization process is the same as that in step (4).
Preferably, in the step (7), the precision filter has a filtration precision of 5 um.
Ultrapure water is prepared by the method for treating the fluorine-containing reuse water.
The ultrapure water is applied to the process of manufacturing integrated circuits and cleaning circuit boards.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention provides a method for treating fluorine-containing reuse water, which is used for treating fluorine-containing wastewater (especially fluorine-containing wastewater in the electronic industry) and has the following advantages: firstly, the removal rate of fluorine ions in the wastewater is high, and the level of ultrapure water can be reached; secondly, the fluorine ion removal efficiency is high; thirdly, the recovery rate of the wastewater can be greatly improved, and the running cost of the ultrapure water preparation system is obviously reduced;
(2) the invention provides a method for treating fluorine-containing reuse water, which comprises the steps of firstly, carrying out flocculation precipitation and filtration treatment on waste water to remove CaF2Precipitating particles and other solid impurities in the wastewater to prevent the blockage of the permeable membrane in the next step; then, a reverse osmosis membrane is used for treating the wastewater, so that soluble substances such as sodium, calcium, magnesium, chloride, nitrate, carbonate and the like are removed, the hardness of a water body is reduced, and calcium and magnesium scales are prevented from influencing subsequent treatment steps; then, treating the effluent by adopting a first-level EDI technology, and removing dissolved gas, boron and silicon dioxide; followed by nano-hydration using a filling with a loadingThe secondary EDI system of the porous polystyrene resin of zirconia is used for treating the wastewater, so that the fluorine content in the water body is further reduced; finally, performing TOC secondary degradation and ultraviolet sterilization on the water body, namely performing precise filtration to ensure that the water quality of the outlet water reaches the level of ultrapure water;
(3) in a conventional ultrapure water production system, impurity ions in raw water are generally removed by an RO/EDI integration technique, but the target of the above technique is mostly tap water. However, in the present patent application, the radius of the contained fluorine ions is small, and the content of the fluorine ions in the effluent of the reverse osmosis membrane is still high, and for the conventional EDI technology, when the ion exchange resin removes the impurity ions in the wastewater by using the ion exchange principle, the fluorine ions are ranked relatively backward, so the removal effect of the fluorine ions is affected by anions such as sulfate radicals, nitrate radicals, chromate radicals, bromide ions, cyanide ions, chloride ions and the like, and the electronic wastewater contains a large amount of anions, so when the recycled electronic wastewater is used as raw water of an ultrapure water preparation system, the fluorine removal effect of the EDI technology is not ideal;
based on the above, the invention provides a method for treating fluorine-containing reuse water, which is a method for combining primary EDI treatment and secondary EDI treatment on a water body, and is used for treating fluorine-containing wastewater; in the treated secondary EDI system, the adopted resin is porous polystyrene resin loaded with nano hydrous zirconia, and the method has the following advantages: firstly, water is dissociated into hydrogen ions and hydroxide ions through polarization in an ion exchange resin and an interface diffusion layer of the ion exchange membrane in contact with water, the hydrogen ions and the hydroxide ions are used for regeneration of the resin besides loading current, and the nano hydrous zirconia loaded on the resin enhances the conductivity of the resin, so that more hydrogen ions and hydroxide ions can be used for regenerating the resin, and the regeneration rate of the resin is ensured; secondly, in the conventional EDI technique, water is dissociated under the action of an electric field to generate hydrogen ions and hydroxyl ions, and a part of the ions are dissociated for resin regeneration and the other part is used for carrying current. In the technology, the porous polystyrene resin loaded with the nano-hydrous zirconia is loaded with the nano-hydrous zirconia to enhance the conductivity of the resin, so that more hydrogen ions and hydroxyl ions generated by water electrolysis are used for resin regeneration, the removal effect of the ion exchange resin on impurity ions is improved, and the defluorination effect of the defluorination resin is enhanced;
(4) for the existing fluorine removal technology of porous polystyrene resin loaded with nano-hydrated zirconia, after fluorine removal is carried out for a period of time in the use process, a desorption agent is needed to desorb the fluorine removal resin, and the desorption regeneration of the resin can greatly increase the operation cost of the resin during fluorine removal. In order to improve the feasibility of industrial popularization of the special defluorinating resin, the technology combines electrodialysis and ion exchange resin to realize continuous regeneration of the novel defluorinating resin, saves the cost required by desorption regeneration in the use process of the resin, and greatly reduces the operation cost of the special defluorinating resin during defluorination.
Detailed Description
The invention is further described with reference to specific examples.
Example 1
In the embodiment, 2L of fluorine-containing wastewater in the electronic industry is taken from a microelectronic manufacturing plant, the pH value of raw water is 2.84, the COD concentration is 86mg/L, and the fluorine ion concentration is 364mg/L (the fluorine ion concentration in the wastewater is measured by using a direct ion selective electrode method, the lower detection limit is 15.1 mug/L), and the wastewater is treated by using the treatment method provided by the invention, and the specific steps are as follows:
(1) and adjusting the pH value of the wastewater to 8-9, and introducing an excessive calcium hydroxide solution and a calcium chloride solution into the wastewater to perform a chemical precipitation reaction to generate calcium fluoride.
(2) Flocculating and precipitating, namely (1) introducing a coagulant PAC into the wastewater after a chemical precipitation reaction to enable fine precipitates to generate larger particles, then adjusting the pH of the wastewater to 6-7, and then introducing a flocculant PAM to enhance the precipitation effect.
(3) And (3) taking the supernatant in the step (2), removing solid impurities in the wastewater by using a cylindrical filter, and removing soluble substances such as sodium, calcium, magnesium, chloride, nitrate, carbonate and the like from the wastewater by using a reverse osmosis membrane.
(4) TOC degradation and ultraviolet sterilization, wherein TOC degradation treatment is carried out on the effluent of the reverse osmosis membrane (by utilizing a TOC degradation device), and then ultraviolet irradiation treatment is carried out, so that hydroxyl free radicals can be generated in water through high-dose UV-185nm ultraviolet catalysis, and organic matters in the water are subjected to oxidative degradation, so that the TOC content in the water is reduced;
and (4) treating the effluent after TOC degradation by using a UV-254nm ultraviolet sterilizer.
(5) EDI treatment, namely treating the effluent in the step (4) by using an electrodeionization system, wherein the resin filled in the electrodeionization system is porous polystyrene resin loaded with nano hydrous zirconia; the specific processing parameters are as follows: the pH value of inlet water is 5.8-8.0; the temperature is 5-35 ℃; the water inlet pressure is 1.5-4kg/cm2
The water quality of the wastewater after EDI treatment is shown in Table 1:
TABLE 1 EDI quality of treated wastewater
(6) TOC degradation and ultraviolet sterilization, performing TOC degradation treatment on EDI effluent (by using a TOC degradation device), and sterilizing by using an UV-254nm ultraviolet sterilizer.
(7) A precision filter: the water after the ultraviolet irradiation treatment is filtered by a precision filter (PP spray-melting type filter element with the filter element precision of 5 um).
The total effluent quality is shown in table 2:
TABLE 2 Total effluent quality
In the table, "-" indicates that the fluorine ion concentration in the water body is lower than the lower detection limit of 15.1. mu.g/L.
As can be seen from the data in tables 1 and 2, after the wastewater is treated by the newly developed defluorination technology, the removal rate of the fluoride ions in the wastewater reaches 95%, the wastewater is further subjected to advanced treatment by a TOC degrader, a polishing mixed bed, an ultraviolet sterilizer and a precision filter, the existence of the fluoride ions is not detected by using a direct ion selective electrode method, the removal rate of the fluoride ions in the whole process reaches more than 99%, and the quality of effluent meets the requirement of ultrapure water in the electronic industry.
Example 2
In the embodiment, 2L of fluorine-containing wastewater in the electronic industry is taken from a microelectronic manufacturing plant, the pH value of raw water is 2.84, the COD concentration is 86mg/L, and the fluorine ion concentration is 364mg/L (the fluorine ion concentration in the wastewater is measured by using a direct ion selective electrode method, the lower detection limit is 15.1 mug/L), and the wastewater is treated by using the treatment method provided by the invention, and the specific steps are as follows:
(1) adjusting the pH value of the wastewater to 8-9, and introducing an excessive calcium hydroxide solution and a calcium chloride solution into the wastewater to perform a chemical precipitation reaction to generate calcium fluoride; the mass concentration of fluorine in the water body is taken as a reference, and the adding amount of the calcium hydroxide isThe dosage of the calcium chloride is
(2) Flocculating and precipitating, namely (1) introducing a coagulant PAC into the wastewater subjected to the chemical precipitation reaction to enable fine precipitates to generate larger particles, then adjusting the pH of the wastewater to 6-7, and then introducing a flocculant PAM to enhance the precipitation effect; the coagulant is PAC, the mass concentration of fluorine in the water body is taken as a reference, and the adding amount is CPAC=4CF -(ii) a The flocculant is PAM, the mass concentration of fluorine in the water body is taken as a reference, and the adding amount is CPAM=4CF -. After the treatment, the pH of the effluent was 7.96, the COD was 41mg/L, and the fluoride ion concentration was 3.2 mg/L.
(3) And (3) taking the supernatant in the step (2), removing solid impurities in the wastewater by using a cylindrical filter, and removing soluble substances such as sodium, calcium, magnesium, chloride, nitrate, carbonate and the like from the wastewater by using a reverse osmosis membrane.
(4) Treating the effluent of the reverse osmosis membrane by using a TOC degradation device (UV-185nm low-pressure high-energy ultraviolet technology), and then generating hydroxyl radicals in water by using high-dose UV-185nm ultraviolet catalysis in combination with a UV-254nm ultraviolet sterilizer so as to oxidize and degrade organic matters in the water to reduce the TOC content in the water;
then sterilizing with UV-254nm ultraviolet sterilizer.
(5) EDI treatment, namely performing primary EDI treatment on the effluent obtained in the step (4) by using an electrodeionization system filled with gel type strong resin; the specific processing parameters are as follows: the pH value of inlet water is 5.8-8.0; the temperature is 5-35 ℃; the water inlet pressure is 1.5-4kg/cm2
Then, an electrodeionization system filled with porous polystyrene resin loaded with nano hydrous zirconia is used for carrying out secondary EDI treatment on the wastewater, and the specific treatment parameters are as follows: the pH value of inlet water is 5.8-8.0; the temperature is 5-35 ℃; the water inlet pressure is 1.5-4kg/cm2. The water quality of the wastewater after EDI treatment is shown in Table 3:
TABLE 3 EDI quality of treated wastewater
(6) And (3) disinfecting the EDI treated wastewater by a secondary TOC degradation device, a polishing mixed bed and a UV-254nm ultraviolet sterilizer.
(7) A precision filter: the water after the ultraviolet irradiation treatment was filtered with a precision filter (using a PP spray-melt filter element with a filter element precision of 5um) to prepare high resistivity electronic grade ultrapure water, and the effluent quality is shown in table 4:
TABLE 4 Total effluent quality
In the table, "-" indicates that the fluorine ion concentration in the water body is lower than the lower detection limit of 15.1. mu.g/L.
As can be seen from the data in tables 3 and 4, after the wastewater is treated by the newly developed defluorination technology, the removal rate of the fluoride ions in the wastewater reaches 95%, the wastewater is further subjected to advanced treatment by a TOC degrader, a polishing mixed bed, an ultraviolet sterilizer, a 0.1um cylindrical filter and an ultrafiltration assembly, the existence of the fluoride ions is not detected by using a direct ion selective electrode method, the removal rate of the fluoride ions in the whole process reaches more than 99%, and the quality of effluent meets the requirement of ultrapure water in the electronic industry.
Example 3
In the embodiment, 2L of fluorine-containing wastewater in the electronic industry is taken from a microelectronic manufacturing plant, the pH value of raw water is 2.84, the COD concentration is 86mg/L, and the fluorine ion concentration is 364mg/L (the fluorine ion concentration in the wastewater is measured by using a direct ion selective electrode method, the lower detection limit is 15.1 mug/L), and the wastewater is treated by using the treatment method provided by the invention, and the specific steps are as follows:
(1) adjusting the pH value of the wastewater to 8-9, and introducing an excessive calcium hydroxide solution and a calcium chloride solution into the wastewater to perform a chemical precipitation reaction to generate calcium fluoride; the mass concentration of fluorine in the water body is taken as a reference, and the adding amount of the calcium hydroxide isThe dosage of the calcium chloride is
(2) Flocculating and precipitating, namely (1) introducing a coagulant PAC into the wastewater after a chemical precipitation reaction to enable fine precipitates to generate larger particles, then adjusting the pH of the wastewater to 6-7, and then introducing a flocculant PAM to enhance the precipitation effect.
(3) And (3) taking the supernatant in the step (2), removing solid impurities in the wastewater by using a cylindrical filter, and removing soluble substances such as sodium, calcium, magnesium, chloride, nitrate, carbonate and the like from the wastewater by using a reverse osmosis membrane.
(4) TOC degradation and ultraviolet sterilization, wherein TOC degradation treatment is carried out on the effluent of the reverse osmosis membrane (by utilizing a TOC degradation device), and then ultraviolet irradiation treatment is carried out, so that hydroxyl free radicals can be generated in water through high-dose UV-185nm ultraviolet catalysis, and organic matters in the water are subjected to oxidative degradation, so that the TOC content in the water is reduced;
and (4) treating the effluent after TOC degradation by using a UV-254nm ultraviolet sterilizer.
(5) EDI treatment, namely treating the effluent in the step (4) by using an electrodeionization system, wherein the resin filled in the electrodeionization system is porous polystyrene resin loaded with nano hydrous zirconia; the specific processing parameters are as follows: the pH value of inlet water is 5.8-8.0; the temperature is 5-35 ℃; the water inlet pressure is 1.5-4kg/cm2
(6) TOC degradation and ultraviolet sterilization, performing TOC degradation treatment on EDI effluent (by using a TOC degradation device), and sterilizing by using an UV-254nm ultraviolet sterilizer.
(7) A precision filter: the water after the ultraviolet irradiation treatment is filtered by a precision filter (PP spray-melting type filter element with the filter element precision of 5 um).
After treatment, the existence of fluorine ions is not detected by using a direct ion selective electrode method, the removal rate of the fluorine ions in the whole process reaches over 95 percent, and the water quality of effluent meets the requirement of ultrapure water in the electronic industry.
Example 4
In the embodiment, 2L of fluorine-containing wastewater in the electronic industry is taken from a microelectronic manufacturing plant, the pH value of raw water is 2.84, the COD concentration is 86mg/L, and the fluorine ion concentration is 364mg/L (the fluorine ion concentration in the wastewater is measured by using a direct ion selective electrode method, the lower detection limit is 15.1 mug/L), and the wastewater is treated by using the treatment method provided by the invention, and the specific steps are as follows:
(1) and adjusting the pH value of the wastewater to 8-9, and introducing an excessive calcium hydroxide solution and a calcium chloride solution into the wastewater to perform a chemical precipitation reaction to generate calcium fluoride.
(2) Flocculating and precipitating, namely (1) introducing a coagulant PAC into the wastewater subjected to the chemical precipitation reaction to enable fine precipitates to generate larger particles, then adjusting the pH of the wastewater to 6-7, and then introducing a flocculant PAM to enhance the precipitation effect; the coagulant is PAC, the mass concentration of fluorine in the water body is taken as a reference, and the adding amount is CPAC=4CF -(ii) a The flocculant is PAM, the mass concentration of fluorine in the water body is taken as a reference, and the adding amount is CPAM=4CF -
(3) And (3) taking the supernatant in the step (2), removing solid impurities in the wastewater by using a cylindrical filter, and removing soluble substances such as sodium, calcium, magnesium, chloride, nitrate, carbonate and the like from the wastewater by using a reverse osmosis membrane.
(4) TOC degradation and ultraviolet sterilization, wherein TOC degradation treatment is carried out on the effluent of the reverse osmosis membrane (by utilizing a TOC degradation device), and then ultraviolet irradiation treatment is carried out, so that hydroxyl free radicals can be generated in water through high-dose UV-185nm ultraviolet catalysis, and organic matters in the water are subjected to oxidative degradation, so that the TOC content in the water is reduced;
and (4) treating the effluent after TOC degradation by using a UV-254nm ultraviolet sterilizer.
(5) EDI treatment, namely treating the effluent in the step (4) by using an electrodeionization system, wherein the resin filled in the electrodeionization system is porous polystyrene resin loaded with nano hydrous zirconia; the specific processing parameters are as follows: the pH value of inlet water is 5.8-8.0; the temperature is 5-35 ℃; the water inlet pressure is 1.5-4kg/cm2
(6) TOC degradation and ultraviolet sterilization, performing TOC degradation treatment on EDI effluent (by using a TOC degradation device), and sterilizing by using an UV-254nm ultraviolet sterilizer.
(7) A precision filter: the water after the ultraviolet irradiation treatment is filtered by a precision filter (PP spray-melting type filter element with the filter element precision of 5 um).
After treatment, the existence of fluorine ions is not detected by using a direct ion selective electrode method, the removal rate of the fluorine ions in the whole process reaches over 95 percent, and the water quality of effluent meets the requirement of ultrapure water in the electronic industry.
Comparative example 1
This comparative example differs substantially from example 2 only in that:
the first EDI treatment in step (5) is the same as the electrodeionization system of the second EDI treatment (i.e., the filled resins are all gel type strong resins)
The water quality of the wastewater after EDI treatment is shown in Table 5:
TABLE 5 quality of wastewater after EDI treatment
TABLE 6 Total effluent quality
As can be seen from the data in tables 5 and 6, after the reclaimed fluorine-containing wastewater is treated by the conventional EDI technology, the removal rate of the fluorine ions in the wastewater is 23%, and the effluent quality can not meet the requirement of ultrapure water in the electronic industry after the wastewater is further subjected to advanced treatment by a TOC degradation device, a polishing mixed bed, an ultraviolet sterilizer, a 0.1um cylindrical filter and an ultrafiltration assembly. Therefore, if the fluorine-containing wastewater after the primary fluorine removal treatment is reused as raw water of an ultrapure water system, ultrapure water meeting the industrial production requirements cannot be prepared by using an ultrapure water preparation system composed of a conventional EDI device, so that the ultrapure water preparation system needs to be further improved when the fluorine-containing wastewater is recycled.
Comparative example 2
This comparative example differs substantially from example 2 only in that:
in the step (5), the EDI treatment technology is replaced by an electrodialysis treatment method.
The basic conditions are as follows: assembling three stages of membranes by adopting a die type clapboard electrodialyzer 400 x 800mm and 150 pairs of membranes;
polyethylene heterogeneous membranes are selected.
TABLE 7 Water quality before and after electrodialysis treatment
TABLE 8 Total effluent quality
It can be seen from the data in tables 7 and 8 that, after the recycled fluorine-containing wastewater is treated by the conventional electrodialysis technology, the removal rate of the fluoride ions in the wastewater is only 14%, even if the wastewater is further subjected to advanced treatment by a TOC degrader, a polishing mixed bed, an ultraviolet sterilizer, a 0.1um cylindrical filter and an ultrafiltration module, the content of the fluoride ions is still high, and the quality of the effluent water does not meet the requirement of ultrapure water in the electronic industry. Therefore, if the fluorine-containing wastewater after the preliminary fluorine removal treatment is reused as raw water of an ultrapure water system, ultrapure water satisfying industrial production requirements cannot be prepared by using an ultrapure water preparation system composed of a conventional electrodialysis device.

Claims (8)

1. A method for treating fluorine-containing reuse water is characterized by comprising the following steps:
(1) pretreating, namely introducing excessive calcium hydroxide and calcium chloride into fluorine-containing wastewater with the pH value of 8-9;
(2) flocculating and precipitating, namely adding a coagulant into the pretreated water body, then adjusting the pH value of the wastewater to 6-7, and then introducing a flocculating agent;
(3) filtering, namely taking supernatant from the wastewater after flocculation and precipitation, filtering, and then performing reverse osmosis treatment by using a reverse osmosis membrane;
(4) TOC degradation and ultraviolet sterilization, namely performing TOC degradation and ultraviolet irradiation sterilization treatment on the effluent of the reverse osmosis membrane;
(5) EDI treatment, namely treating the water body subjected to ultraviolet irradiation sterilization treatment by using an electrodeionization system, wherein the resin filled in the electrodeionization system is porous polystyrene resin loaded with nano hydrous zirconia;
(6) TOC degradation and ultraviolet sterilization, namely performing TOC degradation treatment on EDI effluent, and performing ultraviolet irradiation sterilization treatment;
(7) performing precision filtration, namely filtering the water body after ultraviolet irradiation treatment by using a precision filter;
in the step (5), the EDI treatment is specifically that the effluent water obtained in the step (4) is subjected to first-stage EDI treatment and then to second-stage EDI treatment, wherein the resin filled in the electrodeionization system of the second-stage EDI treatment is porous polystyrene resin loaded with nano hydrous zirconia;
during the second-stage EDI treatment, the fluorine ions in the inlet water are concentratedThe degree is 0-5 mg/L; the specific processing parameters are as follows: the pH value of inlet water is 5.8-8.0; the temperature is 5-35 ℃; the water inlet pressure is 1.5-4kg/cm2
2. The method for treating fluorine-containing reuse water according to claim 1, wherein in the step (1), the calcium hydroxide is added in an amount of about equal to the mass concentration of fluorine in the water bodyThe dosage of the calcium chloride is
3. The method according to claim 1, wherein in the step (2), the coagulant is PAC, and the addition amount thereof is C based on the mass concentration of fluorine in the water bodyPAC=4CF -(ii) a The flocculant is PAM, the mass concentration of fluorine in the water body is taken as a reference, and the adding amount is CPAM=4CF -
4. The method for treating fluorine-containing reuse water according to claim 1, wherein in the step (4), the ultraviolet irradiation is performed by treating the effluent after TOC degradation with a UV-254nm ultraviolet sterilizer.
5. The method for treating fluorine-containing reuse water according to claim 4, wherein in the step (5), the upper limit of the concentration of fluorine ions in the feed water of the secondary EDI treatment is 5 mg/L.
6. The method for treating fluorine-containing reuse water according to claim 1, wherein in the step (7), the filtration precision of the precision filter is 5 μm.
7. Ultrapure water, which is produced by the method for treating fluorine-containing reuse water according to any one of claims 1 to 6.
8. Use of ultrapure water according to claim 7 for the cleaning of circuit boards in processes for the manufacture of integrated circuits.
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