CN211712837U - System for removing sulfate in water and water treatment system comprising same - Google Patents
System for removing sulfate in water and water treatment system comprising same Download PDFInfo
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- CN211712837U CN211712837U CN202020212313.4U CN202020212313U CN211712837U CN 211712837 U CN211712837 U CN 211712837U CN 202020212313 U CN202020212313 U CN 202020212313U CN 211712837 U CN211712837 U CN 211712837U
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- ettringite
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- aluminum hydroxide
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 85
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 title claims abstract description 82
- 238000011282 treatment Methods 0.000 title claims abstract description 28
- 229910001653 ettringite Inorganic materials 0.000 claims abstract description 116
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 claims abstract description 76
- 239000002002 slurry Substances 0.000 claims abstract description 59
- 238000011084 recovery Methods 0.000 claims abstract description 47
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims abstract description 24
- 235000011941 Tilia x europaea Nutrition 0.000 claims abstract description 24
- 239000004571 lime Substances 0.000 claims abstract description 24
- 229910021653 sulphate ion Inorganic materials 0.000 claims abstract description 17
- 239000010802 sludge Substances 0.000 claims abstract description 15
- 239000002253 acid Substances 0.000 claims abstract description 11
- 239000012528 membrane Substances 0.000 claims abstract description 8
- 238000001914 filtration Methods 0.000 claims abstract description 3
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims description 93
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 80
- 238000006243 chemical reaction Methods 0.000 claims description 63
- 238000001556 precipitation Methods 0.000 claims description 44
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 40
- 229910052602 gypsum Inorganic materials 0.000 claims description 27
- 239000010440 gypsum Substances 0.000 claims description 26
- 238000003860 storage Methods 0.000 claims description 22
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 claims description 20
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 20
- 229910001424 calcium ion Inorganic materials 0.000 claims description 20
- 238000005352 clarification Methods 0.000 claims description 19
- 239000007788 liquid Substances 0.000 claims description 17
- XFWJKVMFIVXPKK-UHFFFAOYSA-N calcium;oxido(oxo)alumane Chemical group [Ca+2].[O-][Al]=O.[O-][Al]=O XFWJKVMFIVXPKK-UHFFFAOYSA-N 0.000 claims description 16
- 238000002425 crystallisation Methods 0.000 claims description 15
- 230000008025 crystallization Effects 0.000 claims description 15
- 238000001728 nano-filtration Methods 0.000 claims description 15
- 230000020477 pH reduction Effects 0.000 claims description 14
- 239000006228 supernatant Substances 0.000 claims description 14
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical group [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 13
- 238000002156 mixing Methods 0.000 claims description 13
- 238000000926 separation method Methods 0.000 claims description 12
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 10
- 239000008267 milk Substances 0.000 claims description 9
- 210000004080 milk Anatomy 0.000 claims description 9
- 235000013336 milk Nutrition 0.000 claims description 9
- 159000000013 aluminium salts Chemical class 0.000 claims description 7
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 claims description 7
- 239000000292 calcium oxide Substances 0.000 claims description 7
- 235000012255 calcium oxide Nutrition 0.000 claims description 7
- 239000013078 crystal Substances 0.000 claims description 7
- 229910000329 aluminium sulfate Inorganic materials 0.000 claims description 5
- 238000010517 secondary reaction Methods 0.000 claims description 5
- 239000001569 carbon dioxide Substances 0.000 claims description 4
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 4
- JYYOBHFYCIDXHH-UHFFFAOYSA-N carbonic acid;hydrate Chemical compound O.OC(O)=O JYYOBHFYCIDXHH-UHFFFAOYSA-N 0.000 claims description 2
- 239000012141 concentrate Substances 0.000 claims description 2
- 229910021502 aluminium hydroxide Inorganic materials 0.000 claims 3
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 abstract description 16
- 238000000034 method Methods 0.000 description 9
- 229910052782 aluminium Inorganic materials 0.000 description 7
- 239000011575 calcium Substances 0.000 description 7
- 238000003756 stirring Methods 0.000 description 6
- -1 SO) in water4 2- Chemical class 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 238000004064 recycling Methods 0.000 description 5
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 4
- 229910052791 calcium Inorganic materials 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 239000003651 drinking water Substances 0.000 description 4
- 235000020188 drinking water Nutrition 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 229910052593 corundum Inorganic materials 0.000 description 3
- 238000005189 flocculation Methods 0.000 description 3
- 230000016615 flocculation Effects 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 230000035484 reaction time Effects 0.000 description 3
- 229910001845 yogo sapphire Inorganic materials 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- 239000000920 calcium hydroxide Substances 0.000 description 2
- 235000011116 calcium hydroxide Nutrition 0.000 description 2
- 238000003795 desorption Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 150000007522 mineralic acids Chemical class 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 230000003213 activating effect Effects 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000005755 formation reaction Methods 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 238000011221 initial treatment Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000004148 unit process Methods 0.000 description 1
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Abstract
The utility model provides a system for be used for getting rid of sulphate in aquatic, include: a sulfate removal unit for treating sulfate-containing water with aluminum salt and lime to produce sulfate-removed treated water and ettringite slurry; an active aluminum hydroxide recovery unit for treating the ettringite slurry with an acid liquor to produce active aluminum hydroxide and effluent, the produced active aluminum hydroxide being conveyed to a sulfate removal unit for treatment of sulfate-containing water. Based on the technical scheme, the water containing sulfate can be treated by using the active aluminum hydroxide recovered from the ettringite slurry, so that the use amount of aluminum salt is reduced, the sludge output of a system is also reduced, and the sludge treatment cost is reduced. The utility model also provides a water treatment system, including receiving the system of filter membrane processing system and the above-mentioned sulfate that is used for getting rid of the aquatic, the former is used for filtering the incoming water and produces and receive and strain dense water, and the latter is used for getting rid of receive and strain the sulfate in the dense water.
Description
Technical Field
The utility model relates to a system for be used for getting rid of sulphate in aquatic.
Background
The drinking water source in western regions of China usually comes from underground water, but the phenomenon of high sulfate content in the underground water is common in the regions due to special soil conditions, and the water source quantity exceeding the national standard accounts for 10 percent or even higher of the total water source quantity. The groundwater used as the water source of the drinking water treatment plant usually needs to take measures to remove high-concentration sulfate in the water source SO as to reach the sanitary Standard (SO) of domestic drinking water in China4 2-≤250mg/L,GB5749-2006)。
In deep purification of drinking water, nanofiltration membrane is usually used to efficiently trap high valence ions (such as SO) in water4 2-、Ca2+、Mg2+Etc.) and organic contaminants. The nanofiltration membrane treatment process generates about 20-30% of concentrated water, and the nanofiltration concentrated water contains a large amount of sulfate ions intercepted and concentrated by the membrane, so that the problem of secondary pollution is caused if the concentrated water is directly discharged without treatment. Among the methods for treating such nanofiltration concentrated water containing high concentration of sulfate, the ettringite precipitation method has been widely regarded for its simple operation, excellent treatment effect and low cost. The theory of the ettringite precipitation method is that sulfate reacts with calcium and aluminum salt under strong alkaline condition to generate ettringite precipitation, thereby removing sulfate in water.
For sulfate removal systems based on the ettringite precipitation process, the selection of aluminum salt has a great influence on the treatment effect. The best results are aluminium trichloride, which is dissolved in water to give a large amount of aluminium salt in solution, but on the one hand the agent is relatively expensive and on the other hand chloride ions are introduced after use of the agent, resulting in an increase in the salt content of the produced water. Calcium aluminate is generally used, which provides both aluminium ions and small amounts of calcium ions, and commercially available calcium aluminate powders are generally dodecacalcium heptaluminate, which typically contains around 30% Al2O3About 20 percent of CaO, and most of the rest impurities do not participate in the reactionThe cost of using this agent and the cost of sludge disposal are still high because a large amount of calcium aluminate powder is added to achieve the target sulfate removal rate and a large amount of precipitates are generated as chemical sludge.
Therefore, it is highly desirable to provide a system for removing high concentration sulfate in water that can reduce costs.
SUMMERY OF THE UTILITY MODEL
To this end, the present invention provides a system for removing sulfate in water, comprising: a sulfate removal unit for treating sulfate-containing water with aluminum salt and lime to produce sulfate-removed treated water and ettringite slurry; an active aluminum hydroxide recovery unit for treating the ettringite slurry with an acid liquor to produce active aluminum hydroxide and effluent, the produced active aluminum hydroxide being conveyed to a sulfate removal unit for treatment of sulfate-containing water. Based on the technical scheme, the water containing sulfate can be treated by using the active aluminum hydroxide recovered from the ettringite slurry, so that the use amount of aluminum salt is reduced, the sludge output of a system is also reduced, and the sludge treatment cost is reduced.
Optionally, the system of the utility model can also comprise a gypsum recovery unit, wherein the gypsum recovery unit processes the effluent of the active aluminum hydroxide recovery unit to produce gypsum. Based on the technical scheme, the recycled gypsum can bring additional economic benefits.
Alternatively, the sulphate removal unit may comprise an ettringite reaction cell in which sulphate-containing water, lime and the aluminium salt react; and/or, the sulfate-containing water, lime and activated aluminum hydroxide produced by the activated aluminum hydroxide recovery unit are reacted in the ettringite reaction tank. Based on the technical scheme, in the initial treatment stage, the added aluminum salt is used for reaction; along with the treatment, the adding amount of aluminum salt can be reduced, even the aluminum salt is not added, and the recovered active aluminum hydroxide is used for reaction.
Optionally, the sulfate removal unit may further comprise an ettringite precipitation high density clarifier; and the effluent of the ettringite reaction tank enters an ettringite precipitation high-density clarification tank to realize solid-liquid separation, and supernatant and ettringite slurry are obtained. Based on the technical scheme, the separation of the ettringite slurry can be efficiently realized.
Optionally, the sulfate removal unit may further comprise an acidification reactor; and the supernatant of the ettringite precipitation high-density clarification tank enters an acidification reactor, and carbon dioxide is introduced into the acidification reactor to react with the supernatant. Based on the technical scheme, the alkaline supernatant can be neutralized, and calcium ions in the supernatant are precipitated in the form of calcium carbonate.
Optionally, the sulfate removal unit may further comprise a calcium carbonate precipitation high density clarifier; and the effluent of the acidification reactor enters a calcium carbonate precipitation high-density clarification tank to realize solid-liquid separation, so that treated water and calcium carbonate slurry are obtained. Based on the technical scheme, the separation of the calcium carbonate slurry can be efficiently realized.
Optionally, the sulfate removal unit can also comprise a calcium carbonate slurry storage tank and a calcium carbonate precipitation dehydrator; and the calcium carbonate mud storage pool stores the calcium carbonate mud, and the calcium carbonate mud from the calcium carbonate mud storage pool is dehydrated by the calcium carbonate precipitation dehydrator to obtain a calcium carbonate mud cake. Based on the technical scheme, the calcium carbonate mud cake can be obtained, and the subsequent treatment is convenient.
Optionally, the active aluminum hydroxide recovery unit may comprise an ettringite slurry storage tank and an ettringite dehydrator; the ettringite slurry storage tank stores ettringite slurry, and the ettringite dehydrator dehydrates the ettringite slurry from the ettringite slurry storage tank to obtain ettringite mud cakes. Based on the technical scheme, the ettringite can be concentrated, and the subsequent analytic reaction is facilitated.
Optionally, the active aluminum hydroxide recovery unit may further include an ettringite resolving primary reaction tank; the ettringite mud cake and the sulfuric acid react in an ettringite analysis primary reaction tank. Based on the technical scheme, the ettringite can be resolved by utilizing sulfuric acid to obtain the active aluminum hydroxide.
Optionally, the active aluminum hydroxide recovery unit may further include an ettringite resolving secondary reaction tank; the effluent of the first stage reaction tank for the ettringite resolution and the sulfuric acid react in the second stage reaction tank for the ettringite resolution. It should be noted that, in order to optimize the recovery efficiency of the active aluminum hydroxide, it is feasible to arrange single-stage, two-stage, and more-stage analytical reaction tanks, which can be selected according to actual situations.
Optionally, the active aluminum hydroxide recovery unit may further include an ettringite resolving liquid mixing tank and a resolving, elutriating and concentrating tank; the effluent of the ettringite analysis secondary reaction tank enters an ettringite analysis liquid mixing tank and stays for a period of time, so that the reaction time is increased, and the analysis reaction is fully carried out; the effluent of the ettringite analysis liquid mixing tank enters an analysis elutriation concentration tank, active aluminum hydroxide slurry and effluent are generated through concentration, the effluent is the effluent of an active aluminum hydroxide recovery unit, and the effluent contains more calcium ions and sulfate ions and can be treated by a gypsum recovery unit so as to extract gypsum (calcium sulfate solid) from the effluent.
Optionally, the active aluminum hydroxide recovery unit may further comprise an active aluminum hydroxide sludge dehydrator that dehydrates the active aluminum hydroxide sludge to produce an active aluminum hydroxide sludge cake; the activated aluminum hydroxide cake is transferred to the ettringite reaction tank.
Alternatively, the gypsum recovery unit can include a calcium sulfate crystallization pond that treats the effluent of the active aluminum hydroxide recovery unit such that calcium ions and sulfate ions therein undergo a crystallization reaction to produce an effluent containing calcium sulfate crystals.
Optionally, the gypsum recovery unit can further comprise a calcium sulfate high-density clarification tank, a calcium sulfate slurry storage tank and a calcium sulfate dehydrator; the effluent of the calcium sulfate crystallization tank enters a calcium sulfate high-density clarification tank to undergo solid-liquid separation to generate calcium sulfate slurry, and the calcium sulfate slurry enters a calcium sulfate slurry storage tank; the calcium sulfate dehydrator dehydrates the calcium sulfate slurry from the calcium sulfate slurry reservoir to produce gypsum. Based on the technical scheme, the extraction and separation of the gypsum can be efficiently realized.
Alternatively, the aluminium salt may be calcium aluminate or aluminium chloride, preferably calcium aluminate, since calcium aluminate does not introduce impurity anions and can also provide additional calcium ions; the lime is quicklime or lime milk prepared by adding water to the quicklime, preferably the lime milk is prepared in advance in a lime preparation tank and then put into a mayenite deposition reaction. The acid liquor used in the activated aluminum hydroxide recovery unit is preferably sulfuric acid.
In another aspect of the present invention, there is provided a water treatment system, including: the nanofiltration membrane treatment system is used for filtering the incoming water to generate nanofiltration concentrated water; and any one of the foregoing systems for removing sulfate from water to produce a sulfate-removed treated water.
Drawings
Fig. 1 shows a schematic block diagram of a system for removing sulphate from water according to the present invention;
fig. 2 shows a block diagram according to an embodiment of the invention.
Detailed Description
In order to make the purpose, solution and advantages of the technical solution of the present invention clearer, the drawings of the specific embodiments of the present invention will be combined hereinafter to clearly and completely describe the technical solution of the embodiments of the present invention. Unless otherwise indicated, terms used herein have the ordinary meaning in the art. Like reference symbols in the various drawings indicate like elements.
Fig. 1 is a schematic block diagram illustrating a system for removing sulfate from water in accordance with the present invention.
As shown in fig. 1, the system comprises a sulphate removal unit 100 for treating sulphate-containing water to be treated, such as nanofiltration concentrate water, with aluminium salts and lime milk. An ettringite reaction occurs in the sulfate removal unit 100 and an ettringite slurry is generated, achieving the effect of removing sulfate.
The ettringite reacts as follows:
3CaO+3Ca2++3SO4 2-+2Al(OH)3+31H2O＝[3CaO·3CaSO4·Al2O3(s)·31H2O]+6H+(1)
aluminum salts such as calcium aluminate and aluminum chloride can be used as aluminum sources to provide aluminum ions, the pH of the solution is adjusted to be alkaline, for example, between 11.6 and 12, and therefore, the aluminum ions exist in the form of active aluminum hydroxide; lime milk and the like can be used as a calcium source to provide calcium ions. Preferably, calcium aluminate, which provides both aluminum and calcium ions, is used, reducing the amount of calcium source used.
As shown in fig. 1, the system further includes an active aluminum hydroxide recovery unit 200 for resolving the ettringite slurry generated in the sulfate removal unit 100 with an acid solution to recover active aluminum hydroxide.
The acid solution resolution reaction is as follows:
[3CaO·3CaSO4·Al2O3(s)·31H2O]+6H3O+＝6Ca2++3SO4 2-+2Al(OH)3(s)+37H2O (2)
sulfuric acid solution can be used as the resolving acid solution. The acid solution analysis reaction can be carried out in a primary analysis pool; preferably, it is also possible to perform the process in more than one stage (e.g., two stages) of the desorption bath to increase the recovery rate of the activated aluminum hydroxide.
As shown in fig. 1, the active aluminum hydroxide recovered by the active aluminum hydroxide recovery unit 200 is transferred to the sulfate removal unit 100, and the recovered active aluminum hydroxide may participate in the ettringite reaction (1) as an aluminum source.
Thus, at the initial stage of the treatment, aluminum salt is added to the sulfate removal unit 100 to start the ettringite reaction; with the advancement of treatment, only a small amount of aluminum salt can be added, even no aluminum salt is added, and the recycled active aluminum hydroxide is used for carrying out ettringite reaction, so that the preset sulfate removal effect can be achieved. By recycling the activated aluminum hydroxide, on one hand, the sludge production of the system is greatly reduced, and the sludge disposal cost is reduced; on the other hand, the adding amount of aluminum salt is reduced and the medicament cost is reduced by recycling the active aluminum hydroxide.
In some embodiments of the present invention, a gypsum recovery unit 300 may also be provided, as shown in dashed lines in fig. 1. Referring to the above analytical reaction equation (2), the effluent of the active aluminum hydroxide recovery unit 200 will include a large amount of calcium ions and sulfate ions, and in the gypsum recovery unit 300, a crystallization reaction occurs:
Ca2++SO4 2-+2H2O＝CaSO4·2H2O(s) (3)
gypsum crystals are obtained, which can be shipped or used commercially, as well as other deposits, thereby providing additional economic benefits.
In another aspect of the present invention, a water treatment system is provided, comprising a nanofiltration membrane treatment system and a system according to the present invention for removing sulfate in water. The nanofiltration membrane treatment system filters the incoming water to generate nanofiltration concentrated water; the system for removing the sulfate in the water receives the nanofiltration concentrated water and removes the sulfate in the nanofiltration concentrated water to ensure that the outlet water reaches the corresponding standard
Fig. 2 shows a schematic block diagram of a specific arrangement of a system for removing sulphate from water according to the present invention, wherein the sulphate removal unit 100, the activated aluminium hydroxide recovery unit 200 and the gypsum recovery unit 300 are shown in dashed boxes.
Sulfate removal unit
The sulfate removal unit 100 mainly comprises an ettringite reaction tank 101, an ettringite precipitation high-density clarifier tank 102, an acidification reactor 103 and a calcium carbonate precipitation high-density clarifier tank 104.
The ettringite reaction 101 is the core device for removing sulfate from water to be treated, and the ettringite precipitation-forming reaction (1) takes place in this device. The water to be treated, the lime milk, the aluminum salt and the recycled active aluminum hydroxide all enter the reaction tank to react. A pH monitor is arranged in the reaction tank, and the pH of the reaction tank is controlled between 11.6 and 12 by adding lime milk. The sulfate, calcium ions and aluminum ions in the water to be treated react under the strong alkaline condition to generate ettringite precipitate, so that the sulfate and the water in the water are separated.
The milk of lime may be provided from a lime preparation tank 107. Quicklime (calcium oxide) is mixed with water in a lime preparation tank 107, and hydrolysis reaction is carried out to generate lime milk (calcium hydroxide suspension). The lime preparation tank 107 not only can provide the calcium required for the ettringite precipitation reaction, but also has an important function of maintaining the pH of the ettringite reaction tank to be strong alkaline.
The effluent of the ettringite reaction tank 101 enters an ettringite precipitation high-density clarification tank 102. The ettringite precipitation high-density clarifier 102 is used for realizing solid-liquid separation to obtain ettringite slurry for recycling active aluminum hydroxide. The ettringite precipitation high density clarifier 102 may take various known forms, such as, for example, a high density clarifier patented by suez corporation (CN201439031U), which comprises a flocculation apparatus and a clarification concentration apparatus connected in series. The flocculation reaction device comprises a stirring pool and a mechanical flocculation reactor arranged in the stirring pool, and is connected in series with the hydraulic mixing device behind the stirring pool, and the hydraulic mixing device and the stirring pool are separated by a partition wall. The effluent of the ettringite reaction tank 101 firstly forms concentrated flocs under the action of a flocculant, then enters a hydraulic mixing device through a stirring tank, larger flocs are separated and precipitated at the position, a solution mixed with smaller flocs enters a clarification and concentration device for further separation, the separated ettringite slurry enters an ettringite slurry storage tank 201, and the supernatant enters a subsequent acidification reactor 103.
As lime milk is added into the ettringite reaction tank 101 to remove sulfate, introduced Ca2+The total salt content in the effluent is increased, so that the effluent is difficult to reach the standard, and therefore, an acidification reactor 103 and a calcium carbonate precipitation high-density clarification tank 104 are required to be arranged to remove Ca in the water2+。
The pH of the supernatant from the ettringite precipitation high density clarifier 102 is strongly basic, at which time Ca is present2+No precipitation reaction can occur. Therefore, carbon dioxide is introduced into the supernatant in the acidification reactor 103, and the carbon dioxide reacts with water to form carbonic acid, so that the solution can be effectively acidified; also, carbonate ions in carbonic acid react with calcium ions, and calcium carbonate precipitation formation reaction (4) can occur:
Ca2++CO3 2-＝CaCO3(4)
the effluent of the acidification reactor 103 enters a calcium carbonate precipitation high-density clarification tank 104, and solid-liquid separation is carried out. The calcium carbonate precipitation high density clarifier 104 may take various known forms of clarifiers, such as the same form as the aforementioned ettringite precipitation high density clarifier 102. The supernatant of the calcium carbonate precipitation high-density clarification tank 104 is treated effluent, and the lower calcium carbonate slurry enters a calcium carbonate slurry storage tank 105 and is dehydrated by a calcium carbonate precipitation dehydrator 106 to prepare calcium carbonate slurry cakes.
Recovery unit of activated aluminium hydroxide
The activated aluminum hydroxide recovery unit 200 is shown in dashed outline in fig. 2. The main function of the part is to separate the ettringite out of the active aluminum hydroxide for recycling by adding acid. The concrete device mainly comprises: an ettringite slurry storage tank 201, an ettringite precipitation dehydrator 202, an ettringite analysis primary reaction tank 203, an ettringite analysis secondary reaction tank 204, an ettringite analysis liquid mixing tank 205, an analysis elutriation concentration tank 206 and an active aluminum hydroxide precipitation dehydrator 207.
The ettringite slurry storage tank 201 receives and stores ettringite slurry received from the ettringite precipitation high density clarifier 102. The ettringite slurry has a high water content, and the water comes from the effluent of the ettringite reaction tank 101 and is strongly alkaline. In order to facilitate the subsequent acid-adding analysis reaction, the calcium aluminate sludge is dehydrated by an calcium aluminate precipitation dehydrator 202 to obtain calcium aluminate sludge cake with low water content.
The ettringite mud cake is added into an ettringite analysis primary analysis reaction tank 203, a sulfuric acid solution is also added into the ettringite analysis primary analysis reaction tank 203, and a pH monitor is connected into the ettringite analysis primary analysis reaction tank 203 and is used for monitoring and controlling the acid range in the tank. An ettringite precipitation analysis reaction (2) occurs in the ettringite analysis primary reaction tank 203, and the effluent enters an ettringite analysis secondary analysis reaction tank 204, and a sulfuric acid solution is added into the ettringite analysis secondary analysis reaction tank for further acidification analysis. The effluent of the ettringite analysis secondary analysis reaction tank 204 slightly stays in the ettringite analysis liquid mixing tank 205 to increase the reaction time so that the analysis reaction is fully performed, and then the effluent of the ettringite analysis liquid mixing tank 205 enters the analysis elutriation concentration tank 206.
In the analytic elutriation concentration tank 206, after adding water, stirring and concentrating, supernatant (containing more calcium ions and sulfate ions) of the upper layer enters a subsequent calcium sulfate crystallization tank 301; the active aluminum hydroxide slurry on the lower layer enters an active aluminum hydroxide precipitation dehydrator 207 for dehydration to obtain an active aluminum hydroxide slurry cake, and the active aluminum hydroxide slurry cake is added into the ettringite reaction tank 101 again for recycling.
-a gypsum recovery unit
The gypsum recovery unit 300 is shown in dashed outline in fig. 2. The main function of this part is to crystallize the supernatant in the desorption elutriation concentration tank 206 to obtain gypsum (calcium sulfate) and recover the gypsum, and the specific device mainly comprises: a calcium sulfate crystallization tank 301, a calcium sulfate precipitation high-density clarification tank 302, a calcium sulfate slurry storage tank 303 and a calcium sulfate precipitation dehydrator 304.
In the calcium sulfate crystallization tank 301, calcium ions and sulfate ions are subjected to crystallization reaction under specific conditions to prepare calcium sulfate crystals. The crystallization reaction can be controlled by various known methods, and one method is exemplified here: mixing calcium ions and sulfate with inorganic acid and a crystal modifier to ensure that the concentrations of a calcium ion solution and a sulfate solution are both 0.1-1.0 mol/L, the concentration of the inorganic acid is 0.1-1.0 mol/L, the reaction temperature is 105-112 ℃, the reaction time is 1-4 hours, and under the condition, the crystallization reaction controls to grow out primary calcium sulfate whiskers (see CN 1033288118A).
The primary calcium sulfate whisker can be prepared into a finished product only by drying treatment. Therefore, the primary calcium sulfate crystals prepared in the calcium sulfate crystallization tank 301 firstly enter the calcium sulfate precipitation high-density clarification tank 302, the calcium sulfate crystals in the high-density clarification tank 302 are firstly separated from water and then enter the calcium sulfate slurry storage tank 303, and then the calcium sulfate precipitation dewatering machine 304 is used for further drying and dewatering, so that the finished product is gypsum, and the gypsum can be transported outside or used for commercial use.
Examples:
a practical embodiment is described below to exhibit the effects and advantages of the present invention.
Incoming water to be treated: concentrated water of a water treatment plant, sulfate SO4 2-374mg/L, pH 8.4, total alkalinity of 157mg/L (calculated as calcium carbonate), hardness of 344mg/L (calculated as calcium carbonate), magnesium ionThe content is 51mg/L, the content of calcium ions is 53.7mg/L, and the content of chloride ions is 193 mg/L.
The system shown in FIG. 2 is used for treating the incoming water with the target of sulfate SO4 2-Less than 200mg/L, adding calcium aluminate as aluminum salt in the treatment process, and controlling Al3+The concentration is 74mg/L, Ca (OH) is added2The concentration was 454 mg/L. When removing sulfate in the concentrated water, respectively recovering activated aluminum hydroxide (i.e. activating the activated aluminum hydroxide recovery unit 200) and not recovering activated aluminum hydroxide (i.e. deactivating the activated aluminum hydroxide recovery unit 200), on the premise that the treatment targets are all achieved, calculating and finding that:
when active aluminum hydroxide is recovered, the dosage of the calcium aluminate is 53 kg/h; the adding amount of the calcium aluminate during the recovery of the inactive aluminum hydroxide is 1046kg/h, so that the consumption of the calcium aluminate is greatly reduced by recovering the active aluminum hydroxide.
When active aluminum hydroxide is recovered, 1kg of sulfate is removed to generate 0.82kg of lime pre-precipitate, 0.48kg of calcium carbonate and 3.58kg of calcium sulfate, and the total amount of the three is 4.88 kg; when inactive aluminum hydroxide is recovered, 1kg of sulfate is removed to generate 0.82kg of lime pre-precipitation, 0.32kg of calcium carbonate and 4.29kg of calcium sulfate, and the total amount of the three is 5.43 kg.
Exemplary embodiments of the present invention have been described in detail herein with reference to the preferred embodiments, however, it will be understood by those skilled in the art that various modifications and changes may be made to the above specific embodiments without departing from the scope of the present invention, and various combinations of the various features and structures of the present invention may be made without departing from the spirit of the present invention.
Claims (16)
1. A system for removing sulfate from water, comprising:
a sulphate removal unit (100) for treating sulphate-containing water with aluminium salts and lime to produce sulphate-removed treated water and ettringite slurry;
an active aluminum hydroxide recovery unit (200) for treating the ettringite slurry with an acid solution to produce active aluminum hydroxide and effluent;
wherein the generated active aluminium hydroxide is transported to a sulphate removal unit (100) for treatment of sulphate containing water.
2. The system of claim 1, further comprising a gypsum recovery unit (300), the gypsum recovery unit (300) processing the effluent of the activated aluminum hydroxide recovery unit (200) to produce gypsum.
3. The system according to claim 1 or 2,
the sulphate removal unit (100) comprises an ettringite reaction tank (101),
sulphate-containing water, lime and the aluminium salt react in the ettringite reaction tank (101); and/or the presence of a gas in the gas,
the sulphate-containing water, lime and active aluminium hydroxide produced by the active aluminium hydroxide recovery unit (200) are reacted in the ettringite reaction tank (101).
4. The system of claim 3,
the sulfate removal unit (100) also includes an ettringite precipitation high density clarifier (102);
and the effluent of the ettringite reaction tank (101) enters an ettringite precipitation high-density clarification tank (102) to realize solid-liquid separation, and supernatant and ettringite slurry are obtained.
5. The system of claim 4,
the sulphate removal unit (100) further comprises an acidification reactor (103);
and the supernatant of the ettringite precipitation high-density clarification tank (102) enters an acidification reactor (103), and carbon dioxide is introduced into the acidification reactor (103) to react with the supernatant.
6. The system of claim 5,
the sulfate removal unit (100) further comprises a calcium carbonate precipitation high density clarifier (104);
and the effluent of the acidification reactor (103) enters a calcium carbonate precipitation high-density clarification tank (104) to realize solid-liquid separation, so that treated water and calcium carbonate slurry are obtained.
7. The system of claim 6,
the sulfate removal unit (100) also comprises a calcium carbonate slurry storage tank (105) and a calcium carbonate precipitation dehydrator (106);
the calcium carbonate mud storage pool (105) stores the calcium carbonate mud, and the calcium carbonate precipitation dehydrator (106) dehydrates the calcium carbonate mud from the calcium carbonate mud storage pool (105) to obtain a calcium carbonate mud cake.
8. The system of claim 3,
the active aluminum hydroxide recovery unit (200) comprises an ettringite slurry storage tank (201) and an ettringite dehydrator (202);
the ettringite slurry storage tank (201) stores ettringite slurry, and the ettringite dehydrator (202) dehydrates the ettringite slurry from the ettringite slurry storage tank (201) to obtain an ettringite slurry cake.
9. The system of claim 8,
the active aluminum hydroxide recovery unit (200) also comprises an ettringite resolving primary reaction tank (203);
the ettringite mud cake and the sulfuric acid react in an ettringite analysis primary reaction tank (203).
10. The system of claim 9,
the active aluminum hydroxide recovery unit (200) also comprises an ettringite resolving secondary reaction tank (204);
the effluent of the first stage reaction tank (203) for resolving the ettringite reacts with sulfuric acid in the second stage reaction tank (204) for resolving the ettringite.
11. The system of claim 10,
the active aluminum hydroxide recovery unit (200) also comprises an ettringite analysis liquid mixing tank (205) and an analysis elutriation concentration tank (206);
the effluent of the ettringite analysis secondary reaction tank (204) enters an ettringite analysis liquid mixing tank (205) and stays for a period of time;
and the effluent of the ettringite analysis liquid mixing tank (205) enters an analysis elutriation concentration tank (206) and is concentrated to generate active aluminum hydroxide slurry and effluent, and the effluent is the effluent of an active aluminum hydroxide recovery unit (200).
12. The system of claim 11,
the active aluminum hydroxide recovery unit (200) further comprises an active aluminum hydroxide dehydrator (207) for dehydrating the active aluminum hydroxide slurry to produce an active aluminum hydroxide sludge cake;
the activated aluminum hydroxide sludge cake is transferred to the ettringite reaction tank (101).
13. The system of claim 2,
the gypsum recovery unit (300) comprises a calcium sulfate crystallization tank (301), and the calcium sulfate crystallization tank (301) is used for treating the effluent of the active aluminum hydroxide recovery unit (200) so as to enable calcium ions and sulfate ions in the effluent to carry out crystallization reaction to generate the effluent containing calcium sulfate crystals.
14. The system of claim 11,
the gypsum recovery unit (300) also comprises a calcium sulfate high-density clarification tank (302), a calcium sulfate slurry storage tank (303) and a calcium sulfate dehydrator (304);
the effluent of the calcium sulfate crystallization tank (301) enters a calcium sulfate high-density clarification tank (302) for solid-liquid separation to generate calcium sulfate slurry, and the calcium sulfate slurry enters a calcium sulfate slurry storage tank (303);
the calcium sulfate dewatering machine (304) dewaters the calcium sulfate slurry from the calcium sulfate slurry reservoir (303) to produce gypsum.
15. The system according to claim 1 or 2, wherein the aluminium salt is calcium aluminate or aluminium chloride; the lime is quicklime or lime milk prepared by adding water into the quicklime; the acid solution is sulfuric acid.
16. A water treatment system, comprising:
the nanofiltration membrane treatment system is used for filtering the incoming water to generate nanofiltration concentrated water; and
the system for removing sulfate from water according to any one of claims 1 to 15, for removing sulfate from the nanofiltration concentrate to yield sulfate-removed treated water.
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| CN202020212313.4U CN211712837U (en) | 2020-02-26 | 2020-02-26 | System for removing sulfate in water and water treatment system comprising same |
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| CN202020212313.4U CN211712837U (en) | 2020-02-26 | 2020-02-26 | System for removing sulfate in water and water treatment system comprising same |
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Address after: 3101, 27th Floor, Building 1, Yard 38, East 3rd Ring North Road, Chaoyang District, Beijing, 100026 Patentee after: Suez Environmental Technology (Beijing) Co.,Ltd. Address before: 100026 31 / F, Taikang financial building, building 1, courtyard 38, East Third Ring Road North, Chaoyang District, Beijing Patentee before: Suez Water Treatment Co,.Ltd. |
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