CN110590012B - Resource utilization method of deep defluorination resin desorption solution - Google Patents

Resource utilization method of deep defluorination resin desorption solution Download PDF

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CN110590012B
CN110590012B CN201910865251.9A CN201910865251A CN110590012B CN 110590012 B CN110590012 B CN 110590012B CN 201910865251 A CN201910865251 A CN 201910865251A CN 110590012 B CN110590012 B CN 110590012B
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resin
desorption
fluorine
alkali liquor
concentration
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CN110590012A (en
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卢永
汪林
黄如全
张炜铭
吕振华
朱兆坚
阮志伟
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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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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/42—Treatment of water, waste water, or sewage by ion-exchange
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
    • C02F1/5245—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents using basic salts, e.g. of aluminium and iron
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F2001/007—Processes including a sedimentation step
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/42—Treatment of water, waste water, or sewage by ion-exchange
    • C02F2001/425—Treatment of water, waste water, or sewage by ion-exchange using cation exchangers
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/12—Halogens or halogen-containing compounds
    • C02F2101/14—Fluorine or fluorine-containing compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/16—Regeneration of sorbents, filters

Abstract

The invention discloses a resource utilization method of a deep defluorination resin desorption solution, belonging to the field of resource utilizationIs applied in the field of environmental protection. It comprises the following steps: 1) adopting defluorination resin to carry out adsorption treatment on the fluorine-containing wastewater, and discharging the effluent after reaching the standard; 2) desorbing the defluorinated resin in the step 1) by using alkali liquor as a desorption agent to generate desorption liquid; 3) carbonizing alkali liquor in the desorption solution obtained in the step 2); 4) adding a small amount of CaO or Ca (OH) into the desorption solution obtained after the carbonization treatment in the step 3)2Removing fluorine by precipitation; 5) adding CaO or Ca (OH) into the solution obtained after the solid-liquid separation in the step 4)2Carrying out causticization reaction; 6) softening the supernatant obtained after solid-liquid separation of the precipitate in the step 5) by resin to remove calcium; 7) recycling the high-concentration alkali liquor of the water discharged from the step 6) to the step 2) to be used as a desorption agent. Effectively realizes the resource recycling of the resin desorption liquid for the advanced treatment of the fluorine-containing wastewater, reduces the dosage of the supplementary alkali in the operation process, and greatly reduces the operation cost and the environmental pollution.

Description

Resource utilization method of deep defluorination resin desorption solution
Technical Field
The invention belongs to the technical field of environmental protection, and particularly relates to a resource utilization method of a deep defluorination resin desorption solution.
Background
Wastewater discharged from industries such as fluorine-containing ore mining, metal smelting, rubber, electronics, electroplating and the like often contains high-concentration fluorine ions. The fluorine content in the wastewater far exceeds the national emission standard, and the environment is seriously polluted. At present, the fluoride-containing waste water treatment technologies commonly used at home and abroad mainly comprise two types, namely a precipitation method and an adsorption method. The chemical precipitation method is to form fluoride precipitate by adding chemicals such as calcium salt or the like or to cause fluoride to be adsorbed in the formed precipitate and to be co-precipitated. The method is simple, convenient to treat and low in cost, but the lime has low solubility, and can only be added in emulsion, so that the lime cannot be fully utilized, the dosage is large, the fluorine content in the treated wastewater can only be reduced to 15mg/L generally, and the treated wastewater hardly reaches the first-grade standard of the national standard. Meanwhile, the method also has the defects of slow sedimentation of sludge, difficult dehydration, long period for treating large-flow discharge, unsuitability for continuous treatment and continuous discharge and the like.
For example, the prior art with the publication number of CN 103435190A discloses a method for treating wastewater with high fluorine and chlorine contents, which comprises the following treatment steps: (1) soaking the D201 macroporous anion exchange resin in 50 wt% ethanol water solution for 22 h; (2) passing the wastewater with high fluorine and chlorine contents through D201 macroporous anion exchange resin at a flow rate of 2 BV/h-4 BV/h; (3) collecting the effluent liquid passing through the D201 macroporous anion exchange resin; (4) adding calcium hydroxide into the effluent, wherein the weight of the calcium hydroxide is 1.6-2.0 wt% of the weight of the effluent; (5) then adding calcium chloride, wherein the weight of the calcium chloride is 2.3-2.7 wt% of the weight of the effluent liquid; (6) stirring and standing for 24 hours; (7) taking supernatant liquor, wherein the supernatant liquor is the treated wastewater. The total fluorine content of the wastewater with high fluorine and chlorine content treated by the treatment method is reduced from 303mg/L to 15-24 mg/L, and the total chlorine content is reduced from 286mg/L to 18-29 mg/L.
The adsorption method is that fluorine-containing wastewater flows through adsorption resin and then is subjected to ion exchange with the resin to remove fluoride. The method is suitable for the deep treatment of the low-concentration fluorine-containing wastewater or the wastewater with the fluoride concentration reduced to 10-20 mg/L after the treatment by a precipitation method, namely the fluorine-containing wastewater. And the regeneration of the resin and the treatment of the high-concentration regeneration liquid are indispensable parts in the whole operation process, and frequent desorption of the resin, desorption liquid in the regeneration and addition of the regeneration liquid can also cause higher operation cost.
In addition, there are a freezing method, an ion exchange resin defluorination method, an ultrafiltration defluorination method, an electrodialysis method and the like, but because of high treatment cost and low defluorination efficiency, the method is in an experimental stage so far, and is difficult to be popularized and applied to the treatment of industrial fluorine-containing wastewater.
The prior art with the publication number of CN108191118A discloses a method for recovering fluorine ions in wastewater, belonging to the field of wastewater treatment and resource recycling. As shown in fig. 1, the method specifically comprises the steps of enabling fluorine ions in the fluorine-containing wastewater to reach the standard and be discharged through resin adsorption, and treating resin desorption liquid by using a process combining a diffusion dialysis technology and a chemical precipitation method; wherein, the high-alkali effluent in the diffusion dialysis effluent can be used as a resin desorption agent for recycling to a resin desorption section; high-fluorine-containing effluent in diffusion dialysis effluent is precipitated and recovered in a precipitation form by adopting a chemical precipitation method, and filtrate and fluorine-containing wastewater are mixed according to a certain proportion and then introduced into resin for defluorination treatment, so that the fluoride ions in the wastewater are adsorbed and separated by the resin and then recovered in a high-purity calcium fluoride precipitation form. In the method, the alkali in the resin desorption solution is recovered by using a diffusion dialysis technology, so that the alkali consumption required by resin desorption is reduced, and the sewage treatment cost is reduced. However, in the prior art, when a diffusion dialysis method is adopted, when anions with similar molecular weights are separated, the selectivity is poor, fluorine is not sufficiently separated from alkali liquor, the alkali concentration loss is serious, and a large amount of alkali concentration needs to be supplemented when the anions are recycled; and in the process of mixing the effluent and the fluorine-containing wastewater after the fluorine ions are precipitated and then carrying out resin treatment, the situation of resin blockage exists.
Disclosure of Invention
1. Problems to be solved
The invention provides a resource utilization method of a deep defluorination resin desorption liquid, aiming at the problems that in the prior art, when the fluorine concentration in the desorption liquid after resin adsorption is low, the removal rate is low and the alkali liquor in the resin desorption liquid is seriously lost by a precipitation method, the method can realize the deep treatment of fluorine-containing wastewater, the fluorine ion concentration of effluent is discharged up to the standard, the alkali liquor in the resin desorption liquid is further recycled by chemical precipitation and resin softening, the consumption of a desorption agent is greatly reduced, and the problem that the resin is easily blocked by directly recycling the resin desorption agent in the prior art is avoided.
2. Technical scheme
In order to solve the problems, the technical scheme adopted by the invention is as follows:
a resource utilization method of a deep defluorination resin desorption solution comprises the following steps:
1) adopting defluorination resin to carry out adsorption treatment on the fluorine-containing wastewater, and discharging the effluent after reaching the standard;
2) desorbing the defluorination resin in the step 1) by using alkali liquor as a desorption agent to generate desorption liquid;
3) carbonizing alkali liquor in the desorption solution;
4) adding a small amount of CaO or Ca (OH) into the desorption solution obtained after the carbonization treatment in the step 3)2Removing fluorine by precipitation;
5) adding CaO or Ca (OH) into the solution obtained after the solid-liquid separation in the step 4)2Carrying out causticization reaction;
6) softening the supernatant obtained after solid-liquid separation of the precipitate in the step 5) by resin to remove calcium;
7) and 6) recycling the high-concentration alkali liquor of the effluent to the step 2) to be used as a desorption agent.
Preferably, the mass concentration of fluorine contained in the desorption solution in the step 2) is 50-1500 mg/L, and preferably 200-800 mg/L. Aiming at the situation that desorption liquid contains high-concentration alkali liquor and only contains a small amount of fluoride ions, the fluoride ions are difficult to directly precipitate in the mixed liquid, and the fluoride ions in a system with the fluoride ion concentration greatly different from the alkali liquor concentration can be removed through the matching arrangement of the step 3), the step 4) and the step 5), so that the purposes of eliminating the interference of the alkali liquor and not influencing the recovery of the alkali liquor are achieved.
Preferably, the carbonization treatment in step 3) is: and introducing carbon dioxide into the desorption solution. And introducing carbon dioxide into a system containing alkali liquor and fluoride ions to convert the alkali liquor in the system into carbonate, and eliminating the interference of the alkali liquor on fluoride ion precipitation.
Preferably, the introducing speed of the carbon dioxide is 5-20 mL/min, and the introducing time is 5-10 min. Under the condition, the alkali liquor can be fully carbonized.
Preferably, the carbonization treatment temperature in the step 3) is 5-40 ℃.
Preferably, the total mass concentration of the calcium ion added in the step 4) and the step 5) and the mass concentration of the hydroxyl substance in the desorption solution in the step 2) satisfy the following relationship:
[Ca2+]/[OH-]＝0.6～0.75
the calcium ions are only needed to be slightly excessive, and a small amount of fluoride ions contained in the desorption agent can be recycled under the alkaline condition without influencing the subsequent adsorption performance of the resin. The amount of calcium ion [ Ca ] added here2+]Calculated by 0.6-0.75 time of the concentration of the alkali liquor in the desorption solution, wherein the adding amount of calcium in the step 4) is [ Ca2+]5-10% of (C), the amount of calcium ions added in step 5) is [ Ca ]2+]90-95% of the total. By matching with the steps of carbonizing the alkali liquor in the step 3), removing fluorine by precipitation in the step 4) and preparing alkali by causticization in the step 5), the aims of fully removing fluorine ions and recovering high-concentration alkali liquor can be fulfilled.
Preferably, the defluorinating resin in the step 1) is D201.
Preferably, the concentration of the fluorine ions in the fluorine-containing wastewater in the step 1) is 1-30 mg/L, and the pH value is 4-6.
Preferably, after the defluorination resin in the step 2) is desorbed and regenerated by alkali liquor, a system pH is restored by water washing and acid washing.
Preferably, the alkali liquor in the step 2) is NaOH or KOH, and the mass percentage of the alkali liquor is 3-6%. When the concentration of the eluted alkali liquor is higher, the high desorption efficiency is easier to realize.
Preferably, the precipitation process in the step 4) is to firstly stir for 0.3-1 h, and then to stand for precipitation for 0.5-1 h to obtain calcium fluoride precipitate and supernatant.
Preferably, the causticizing process in the step 5) is to stir for 0.3 to 1 hour, then to stand for 0.5 to 1 hour for precipitation to obtain calcium carbonate precipitate, and at this time, the supernatant is high-concentration alkali liquor.
Preferably, the resin of step 6) is a cation exchange resin. Because the concentration of calcium ions in the supernatant formed in the step 5) is higher, excessive calcium ions are adsorbed by resin, so that the concentrations of fluorine ions and calcium ions in the recycled alkali liquor are both in lower levels, and the blockage of defluorination resin is avoided.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention adopts a composite process of alkali liquor carbonization, chemical precipitation and resin softening, and aims at solving the problem that low-concentration fluorine ions in strong-alkaline resin desorption liquid are difficult to precipitate and remove, the desorption alkali liquor is firstly carbonized, and then precipitator is added; wherein the function of the precipitant is two: one is the precipitator CaO or Ca (OH)2Calcium fluoride precipitate is formed with fluoride ion to effectively remove fluoride ion, and the other is precipitator CaO or Ca (OH)2Reacting with carbonate to release hydroxyl for resource application; the resource recycling of the resin desorption liquid for advanced treatment of fluorine-containing wastewater is effectively realized, the alkali concentration in the desorption liquid is reduced little or is nearly not reduced, additional supplementary alkali is not needed during recycling, the alkali consumption in the operation process is effectively reduced, the treatment process has strong operability, and the operation cost and the environmental pollution are greatly reduced;
(2) because the content of fluorine ions in the advanced treatment is low, the concentration of the fluorine ions in desorption liquid adsorbed by resin is also low, generally less than 800mg/L, and the mass percentage content of alkali liquor used as an eluent reaches 3-6% or even higher, and the direct precipitation of the fluorine ions in the mixed liquid is difficult to carry out, the technical scheme of the invention further aims at the fluorine ions with the mass concentration of 50-800 mg/L in concentrated alkali liquor, and the effects of eliminating the interference of the alkali liquor and not influencing the recovery of the alkali liquor are achieved;
(3) the invention avoids directly precipitating fluorine in the desorption solution containing high-concentration alkali liquor, preferably introduces carbon dioxide into the system to enable the alkali liquor to generate carbonate, and eliminates the influence of the carbonate on the precipitation of low-concentration fluorine ions; the carbonization process is further realized by controlling the introduction speed and time of carbon dioxide and the carbonization temperature, and the precipitator added in the next step is combined, so that the fluorine ions can be effectively precipitated, and the high concentration of the alkali liquor can be kept;
(4) the total mass concentration of calcium ions added in the invention is not calculated by the mass concentration of fluorine ions, but calculated by 0.6-0.75 time of the concentration of alkali liquor in desorption solutionThe aim of the invention can be achieved by matching with the steps of carbonizing the alkali liquor in the step 3) and mixing and precipitating in the step 4) and the step 5); further, the calcium adding amount in the step 4) is [ Ca ]2+]5-10% of (C), the amount of calcium ions added in step 5) is [ Ca ]2+]90-95%, the method has the advantages that the precipitation fluorine removal and causticization alkali preparation are realized step by step, the interference of causticization on the precipitation fluorine removal is eliminated, and the fluorine removal efficiency is improved;
(5) according to the invention, dry powder or high-concentration calcium hydroxide suspension is directly added to precipitate the fluorine-containing desorption solution, so that calcium hydroxide or calcium oxide exists as suspension when being added to the desorption solution, undissolved calcium hydroxide or calcium oxide particles are suspended in a system, an adhesive base is provided for the reaction of fluoride ions and/or carbonate ions and calcium ions, calcium fluoride and/or calcium carbonate can be rapidly precipitated, and meanwhile, the calcium fluoride can be fully precipitated and easily separated by properly stirring and standing;
(6) the method adopts the cation resin to soften the desorption solution after chemical precipitation, the calcium ions in the adsorbed water can be reduced to below 1mg/L or even not detected, the problem that the adsorption performance of the resin is influenced because the calcium ions contained in the desorption solution are directly recycled and are easy to block the resin is avoided, and meanwhile, the exchange capacity of the softened resin is large, the adsorption period is longer, and the operation cost is low.
Drawings
FIG. 1 is a schematic flow chart of the prior art of Chinese patent application publication No. CN 108191118A;
FIG. 2 is a process flow diagram of the resource utilization of the resin desorption solution of the present invention;
FIG. 3 is a flow chart of the process employed in comparative example 1B.
Detailed Description
The invention is further described with reference to specific examples.
Example 1
As shown in FIG. 2, the present invention relates to a method for recycling a resin desorption solution for deep fluorine removal, which aims to reduce the treatment cost by recycling a large amount of alkaline solution generated during desorption of a resin adsorbed with fluorine while performing deep fluorine treatment without generating too much waste liquid as much as possible.
Aiming at fluorine-containing wastewater to be subjected to advanced treatment (the water quality is that the concentration of fluorine ions is 1-30 mg/L, and the pH is 4-6), the method comprises the following steps:
1) adopting defluorination resin D201 to carry out adsorption treatment on the fluorine-containing wastewater, wherein the adsorption flow rate is 10BV/h, and the adsorption temperature is 25 ℃; the effluent is discharged after reaching the standard;
2) desorbing the defluorinated resin in the step 1) by using 6% NaOH as a desorption agent in a concurrent desorption mode, wherein the flow rate of desorption liquid is 1BV/h, the desorption temperature is 25 ℃, the consumption of the desorption liquid is 4BV, and desorption liquid is generated and contains 550mg/L of fluorine;
after the resin is desorbed by adopting alkali liquor, a water washing and acid washing recovery system is adopted, wherein the pH value is 5-6, and the resin is used for next adsorption;
3) carbonizing alkali liquor in desorption liquid: and introducing carbon dioxide into the desorption solution. Introducing carbon dioxide into a system containing alkali liquor and fluoride ions, wherein the introduction speed of the carbon dioxide is 15mL/min, the introduction time is 5min, and the temperature is 5 ℃; NaOH in the system is converted into sodium carbonate, and the interference of high-concentration hydroxide radicals in the alkali liquor on the fluoride ion precipitation is eliminated;
4) adding a calcium hydroxide suspension into the desorption solution subjected to carbonization treatment in the step 3) for precipitation, and calculating that the quantity concentration of total substances of added calcium ions and the quantity concentration of hydroxyl substances in the desorption solution in the step 2) satisfy the following relation:
[Ca2+]/[OH-]＝0.6；
the adding amount of calcium ions in the step is the total amount of added calcium ions ([ Ca ]2+]) 10 percent of the total amount of the calcium fluoride, stirring the mixture at the speed of 300rpm for 0.5h, and then standing the mixture for precipitation for 0.5h to obtain calcium fluoride precipitate and supernatant;
5) adding Ca (OH) into the solution obtained after the solid-liquid separation in the step 4)2The suspension is subjected to causticization reaction, and the dosage of calcium ions is [ Ca ]2+]90% of; the precipitation process comprises the steps of firstly stirring at the speed of 300rpm for 0.5h, then standing for precipitation for 0.5h to obtain calcium carbonate precipitation and supernatant, wherein the supernatant is high-concentration sodium hydroxide solution;
6) softening the supernatant obtained after solid-liquid separation of the precipitate in the step 5) by using cation exchange resin to remove calcium, wherein the adsorption flow rate is 5BV/h and the adsorption temperature is 25 ℃;
after the softened resin in the step 6) is adsorbed and saturated, desorption regeneration is carried out on the softened resin by adopting 4% HCl;
7) recycling the high-concentration alkali liquor of the effluent obtained in the step 6) to the step 2) to be used as a desorption agent, wherein the mass percentage of sodium hydroxide in the recycled alkali liquor is 5.8 percent, the concentration of calcium ions contained in the recycled alkali liquor is less than 1mg/L, and the concentration of fluorine ions is less than 30 mg/L;
after 8000BV of fluorine-containing wastewater is continuously treated in the process, the defluorination resin and the softening resin can be kept unblocked.
Comparative example 1A
Treating the fluorine-containing wastewater with the same water quality and the same amount as those in the embodiment 1 of the invention (the concentration of fluoride ions is 1-30 mg/L, and a desorption agent is 6% NaOH) by adopting the steps of the embodiment 1 of the prior art with the Chinese patent application publication number of CN108191118A, and performing adsorption treatment on the fluorine-containing wastewater by using the resin which is the same as that in the step 1) of the embodiment 1 of the invention, wherein the adsorption conditions are the same as those in the embodiment 1 of the invention;
the desorption is carried out by adopting the same conditions as the conditions in the embodiment 1 of the invention, the concentration of the fluorinion in the desorption solution is 500mg/L, and the concentration of NaOH is 6 percent;
respectively adding desorption liquid and water into desorption liquid and water injection ports of a diffusion dialyzer, wherein the flow rate of the desorption liquid is 1L/h, the flow rate ratio of the desorption liquid to the water is 1:1.2, respectively collecting high-fluorine-containing effluent and high-alkali-containing effluent, and detecting that the concentration of fluorine ions in the high-fluorine-containing effluent is 310mg/L and the mass concentration of NaOH is 1.9%; the concentration of fluorine ions in the high alkali containing effluent is 180 mg/L; the mass concentration of NaOH is 3.8%, sodium hydroxide still needs to be added into the alkali liquor until the concentration is 6%, and then the alkali liquor is recycled to the desorption link of the defluorination resin;
adding a calcium chloride solution with the mass concentration of 5% into the obtained high-fluorine effluent at the molar ratio of Ca/F of 1:1.2 to form a mixed solution, stirring and reacting at the rotating speed of 300r/min for 0.5h, standing for 0.5h, performing solid-liquid separation, mixing the effluent with initial fluorine-containing wastewater at the volume ratio of 1:500, and entering a resin adsorption process; however, it should be noted that although calcium ions in the wastewater are diluted, the resin adsorbing fluorine ions is seriously clogged by repeating the above cycle for a long time (continuous treatment at 1000BV), and the resin must be replaced, which increases the cost.
The results show that: compared with the example 1, when the steps of the example 1 in the prior art with Chinese patent application publication No. CN108191118A are adopted for treatment, although the purposes of fluorine removal and alkali liquor recycling can be realized, the following steps still exist: 1) the concentration of the recycled alkali liquor is low, and a large amount of alkali still needs to be added to improve the concentration of the alkali liquor; 2) the defluorinated resin at the front end is easy to block when being used for a long time.
Comparative example 1B
In the comparative example, the same amount of fluorine-containing wastewater (the concentration of fluorine ions is 1-30 mg/L, the desorption agent is 6% NaOH) as that in example 1 is treated by the process flow shown in FIG. 3, and the conditions are basically the same as those in example 1, except that: the same amount of calcium hydroxide as in example 1 was directly added to the desorption solution (desorption solution containing about 545mg/L of fluorine by mass) generated after desorption of the alkali without using the step of carbonization of the alkali solution, and after precipitation and defluorination, the calcium ion concentration of the supernatant was 138mg/L, the fluorine ion concentration was 456mg/L, and the NaOH mass percentage was 6%.
After the resin is softened, the mass percentage of NaOH in the high-concentration alkali liquor of the effluent is 6%, and when the whole process is circularly used for treating the same wastewater for 300BV (the wastewater amount is relative to the amount of the defluorinating resin), the softened resin at the rear end is blocked, and the softened resin needs to be replaced.
The results show that: fluoride ions are difficult to completely precipitate under high alkali liquor concentration, so that a small part of calcium ions and fluoride ions are precipitated under the microenvironment of the resin in the resin softening step, and the softened resin is blocked and needs to be replaced after long-term operation; meanwhile, the alkali liquor contains high-concentration fluorine ions, so that the desorption of the defluorination resin can be influenced when the desorption sleeve is used, the desorption rate of the resin is reduced, and the defluorination resin cannot be directly used for desorption sleeve.
Example 2
As shown in FIG. 2, a method for recycling a resin desorption solution for deep fluorine removal aims at performing deep fluorine treatment, simultaneously generating as little waste liquid as possible, and recycling a large amount of alkali liquor generated during desorption of a resin adsorbed with fluorine to reduce treatment cost.
Aiming at fluorine-containing wastewater to be subjected to advanced treatment (the water quality is that the concentration of fluorine ions is 1-30 mg/L, and the pH is 4-6), the method comprises the following steps:
1) adopting defluorination resin D201 to carry out adsorption treatment on the fluorine-containing wastewater, wherein the adsorption flow rate is 10BV/h, and the adsorption temperature is 25 ℃; the effluent is discharged after reaching the standard;
2) desorbing the defluorinated resin in the step 1) by using 5% KOH as a desorption agent in a concurrent desorption mode, wherein the flow rate of desorption liquid is 1BV/h, the desorption temperature is 25 ℃, the consumption of the desorption liquid is 6BV, and desorption liquid is generated and contains 380mg/L of fluorine by mass;
after the resin is desorbed by adopting alkali liquor, a water washing and acid washing recovery system is adopted, wherein the pH value is 5-6, and the resin is used for next adsorption;
3) carbonizing alkali liquor in desorption liquid: and introducing carbon dioxide into the desorption solution. Introducing carbon dioxide into a system containing alkali liquor and fluoride ions, wherein the introduction speed of the carbon dioxide is 20mL/min, the introduction time is 6min, and the temperature is 25 ℃; KOH in the system is converted into potassium carbonate, and the interference of high-concentration hydroxide radicals in alkali liquor on the precipitation of fluoride ions is eliminated;
4) adding CaO into the desorption solution subjected to carbonization treatment in the step 3) for precipitation, and calculating that the quantity concentration of total substances of added calcium ions and the quantity concentration of hydroxyl substances in the desorption solution in the step 2) satisfy the following relation:
[Ca2+]/[OH-]＝0.7；
the adding amount of calcium ions in the step is the total amount of added calcium ions ([ Ca ]2+]) 8 percent of the total amount of the calcium fluoride, stirring the mixture for 0.3 hour at the speed of 300rpm, and then standing the mixture for precipitation for 1 hour to obtain calcium fluoride precipitate and supernatant;
5) then adding the solution obtained in the step 4) after solid-liquid separation into the solutionCaO is added for causticization reaction, and the dosage of calcium ions is [ Ca ]2+]92% of; the precipitation process comprises the steps of firstly stirring at the speed of 300rpm for 0.3h, then standing for precipitation for 1h to obtain calcium carbonate precipitation and supernatant, wherein the supernatant is high-concentration sodium hydroxide solution;
6) softening the supernatant obtained after solid-liquid separation of the precipitate in the step 5) by using cation exchange resin to remove calcium, wherein the adsorption flow rate is 5BV/h and the adsorption temperature is 25 ℃;
after the softened resin in the step 6) is adsorbed and saturated, desorbing and regenerating the softened resin by adopting 3% HCl;
7) recycling the high-concentration alkali liquor of the effluent obtained in the step 6) to the step 2) to be used as a desorption agent, wherein the mass percentage of potassium hydroxide in the recycled alkali liquor is 4.8 percent, the concentration of calcium ions contained in the recycled alkali liquor is less than 1mg/L, and the concentration of fluorine ions is less than 30 mg/L;
after 7000BV of wastewater containing fluorine is continuously treated in the above process, the defluorinating resin and the softening resin can be kept unblocked.
Example 3
As shown in FIG. 2, a method for recycling a resin desorption solution for deep fluorine removal aims at performing deep fluorine treatment, simultaneously generating as little waste liquid as possible, and recycling a large amount of alkali liquor generated during desorption of a resin adsorbed with fluorine to reduce treatment cost.
Aiming at fluorine-containing wastewater to be subjected to advanced treatment (the water quality is that the concentration of fluorine ions is 1-30 mg/L, and the pH is 4-6), the method comprises the following steps:
1) adopting defluorination resin D201 to carry out adsorption treatment on the fluorine-containing wastewater, wherein the adsorption flow rate is 10BV/h, and the adsorption temperature is 25 ℃; the effluent is discharged after reaching the standard;
2) desorbing the defluorinated resin in the step 1) by adopting 4% NaOH as a desorption agent in a concurrent desorption mode, wherein the flow rate of desorption liquid is 1BV/h, the desorption temperature is 25 ℃, the consumption of the desorption liquid is 4BV, desorption liquid is generated, and the mass concentration of fluorine contained in the desorption liquid is 544 mg/L;
after the resin is desorbed by adopting alkali liquor, a water washing and acid washing recovery system is adopted, wherein the pH value is 5-6, and the resin is used for next adsorption;
3) carbonizing alkali liquor in desorption liquid: and introducing carbon dioxide into the desorption solution. Introducing carbon dioxide into a system containing alkali liquor and fluoride ions, wherein the introduction speed of the carbon dioxide is 5mL/min, the introduction time is 10min, and the temperature is 40 ℃; NaOH in the system is converted into sodium carbonate, and the interference of high-concentration hydroxide radicals in the alkali liquor on the fluoride ion precipitation is eliminated;
4) adding CaO into the desorption solution subjected to carbonization treatment in the step 3) for precipitation, and calculating that the quantity concentration of total substances of added calcium ions and the quantity concentration of hydroxyl substances in the desorption solution in the step 2) satisfy the following relation:
[Ca2+]/[OH-]＝0.75；
the adding amount of calcium ions in the step is the total amount of added calcium ions ([ Ca ]2+]) 5 percent of the total amount of the calcium fluoride, stirring the mixture for 1 hour at the speed of 300rpm, and then standing the mixture for precipitation for 0.6 hour to obtain calcium fluoride precipitate and supernatant;
5) adding CaO suspension into the solution obtained after the solid-liquid separation in the step 4) for causticizing reaction, wherein the adding amount of calcium ions is [ Ca ]2+]95% of; the precipitation process comprises the steps of firstly stirring at the speed of 300rpm for 1 hour, then standing for precipitation for 0.6 hour to obtain calcium carbonate precipitation and supernatant, wherein the supernatant is high-concentration sodium hydroxide solution;
6) softening the supernatant obtained after solid-liquid separation of the precipitate in the step 5) by using cation exchange resin to remove calcium, wherein the adsorption flow rate is 5BV/h and the adsorption temperature is 25 ℃;
after the softened resin in the step 6) is adsorbed and saturated, desorption regeneration is carried out on the softened resin by adopting 5% HCl;
7) recycling the high-concentration alkali liquor of the effluent obtained in the step 5) to the step 2) to be used as a desorption agent, wherein the mass percentage content of sodium hydroxide in the recycled alkali liquor is 3.9 percent, the concentration of calcium ions contained in the recycled alkali liquor is less than 1mg/L, and the concentration of fluorine ions is less than 30 mg/L;
after 8000BV of fluorine-containing wastewater is continuously treated in the process, the defluorination resin and the softening resin can be kept unblocked.
Example 4
The water quality to be treated in the embodiment is basically the same as that in the embodiment 1, and the experimental conditions are basically the same, except that:
the mass concentration of fluorine contained in the desorption solution generated in the step 2) is 1500 mg/L;
step 3) carbonizing alkali liquor in desorption liquid: and introducing carbon dioxide into the desorption solution. Introducing carbon dioxide into a system containing alkali liquor and fluoride ions, wherein the introduction speed of the carbon dioxide is 20mL/min, the introduction time is 10min, and the temperature is 25 ℃;
step 7) recycling the high-concentration alkali liquor discharged from the step 6) to the step 2) to be used as a desorption agent, wherein the mass percentage of sodium hydroxide in the recycled alkali liquor is 5.9%, the concentration of calcium ions contained in the recycled alkali liquor is less than 1mg/L, and the concentration of fluorine ions is less than 30 mg/L;
the treatment conditions of steps 1), 4), 5) and 6) were the same as in example 1;
after 9000BV of fluorine-containing wastewater is continuously treated in the above process, the defluorination resin and the softening resin can be kept unblocked.
Example 5
The water quality to be treated in the embodiment is basically the same as that in the embodiment 1, and the experimental conditions are basically the same, except that:
the mass concentration of fluorine contained in the desorption solution generated in the step 2) is 50 mg/L;
step 3) carbonizing alkali liquor in desorption liquid: and introducing carbon dioxide into the desorption solution. Introducing carbon dioxide into a system containing alkali liquor and fluoride ions, wherein the introduction speed of the carbon dioxide is 5mL/min, the introduction time is 10min, and the temperature is 25 ℃;
step 7) recycling the high-concentration alkali liquor discharged from the step 6) to the step 2) to be used as a desorption agent, wherein the mass percentage of sodium hydroxide in the recycled alkali liquor is 5.8%, the concentration of calcium ions contained in the recycled alkali liquor is less than 1mg/L, and the concentration of fluorine ions is less than 5 mg/L;
the treatment conditions of steps 1), 4), 5) and 6) were the same as in example 1;
after 8500BV of fluorine-containing wastewater is continuously treated in the process, the defluorination resin and the softening resin can be kept unblocked.
The present invention and its embodiments have been described in detail, and the description is not intended to limit, and the drawings are only one embodiment of the invention, and are not intended to limit the invention, and those skilled in the art should understand that they can not inventively design the similar structural modes and embodiments without departing from the spirit of the invention.

Claims (7)

1. A resource utilization method of a deep defluorination resin desorption solution is characterized by comprising the following steps:
1) adopting defluorination resin to carry out adsorption treatment on the fluorine-containing wastewater, and discharging the effluent after reaching the standard;
2) desorbing the defluorinated resin in the step 1) by using alkali liquor as a desorption agent to generate desorption liquid;
3) carbonizing alkali liquor in the desorption solution obtained in the step 2): introducing carbon dioxide into the desorption solution;
4) adding a small amount of CaO or Ca (OH) into the desorption solution obtained after the carbonization treatment in the step 3)2Removing fluorine by precipitation;
5) adding CaO or Ca (OH) into the solution obtained after the solid-liquid separation in the step 4)2Carrying out causticization reaction;
6) softening the supernatant obtained after solid-liquid separation of the precipitate in the step 5) by resin to remove calcium;
7) recycling the high-concentration alkali liquor of the water discharged from the step 6) to the step 2) to be used as a desorption agent;
the quantity concentration of the total substances added by the calcium ions in the step 4) and the step 5) and the quantity concentration of the hydroxyl substances in the desorption solution in the step 2) meet the following relation:
[Ca2+]/[OH-]＝0.6～0.75；
the calcium adding amount in the step 4) is [ Ca ]2+]5-10%, in the step 5), the adding amount of calcium ions is [ Ca ]2+]90-95% of the total.
2. The resource utilization method of the deep defluorination resin desorption solution as claimed in claim 1, wherein the mass concentration of fluorine contained in the desorption solution in the step 2) is 50-1500 mg/L.
3. The resource utilization method of the deep defluorination resin desorption solution as claimed in claim 1, wherein the carbon dioxide is introduced at a speed of 5-20 mL/min for 5-10 min.
4. The resource utilization method of the deep defluorination resin desorption solution according to the claim 3, wherein the carbonization treatment temperature in the step 3) is 5-40 ℃.
5. The resource utilization method of the deep defluorination resin desorption solution as claimed in claim 1, wherein the alkali solution in the step 2) is NaOH or KOH, and the mass percentage content is 3-6%.
6. The resource utilization method of the deep defluorination resin desorption solution as claimed in claim 1, wherein the precipitation process in the step 4) is firstly stirring for 0.3-1 h, and then standing for precipitation for 0.5-1 h; and/or the causticizing process in the step 5) comprises stirring for 0.3-1 h, and then standing and precipitating for 0.5-1 h.
7. The method for recycling the deep defluorination resin desorption solution as claimed in any one of claims 3 to 6, wherein the resin in the step 6) is cation exchange resin.
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