CN111762941A - System and method for treating wastewater by recycling calcium carbonate - Google Patents
System and method for treating wastewater by recycling calcium carbonate Download PDFInfo
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- CN111762941A CN111762941A CN202010470425.4A CN202010470425A CN111762941A CN 111762941 A CN111762941 A CN 111762941A CN 202010470425 A CN202010470425 A CN 202010470425A CN 111762941 A CN111762941 A CN 111762941A
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- calcium carbonate
- calcium oxide
- calcium
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- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 title claims abstract description 264
- 229910000019 calcium carbonate Inorganic materials 0.000 title claims abstract description 132
- 239000002351 wastewater Substances 0.000 title claims abstract description 67
- 238000004064 recycling Methods 0.000 title claims abstract description 51
- 238000000034 method Methods 0.000 title claims abstract description 49
- 239000000292 calcium oxide Substances 0.000 claims abstract description 109
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims abstract description 109
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims abstract description 106
- 238000001354 calcination Methods 0.000 claims abstract description 93
- 239000010802 sludge Substances 0.000 claims abstract description 66
- 238000002425 crystallisation Methods 0.000 claims abstract description 54
- 230000008025 crystallization Effects 0.000 claims abstract description 54
- 239000012528 membrane Substances 0.000 claims abstract description 44
- 238000001704 evaporation Methods 0.000 claims abstract description 36
- 230000008020 evaporation Effects 0.000 claims abstract description 36
- 238000001556 precipitation Methods 0.000 claims abstract description 22
- 238000005352 clarification Methods 0.000 claims abstract description 20
- 238000009434 installation Methods 0.000 claims abstract description 9
- 125000004122 cyclic group Chemical class 0.000 claims abstract description 4
- 230000007246 mechanism Effects 0.000 claims abstract description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 81
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 31
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 25
- 238000001914 filtration Methods 0.000 claims description 25
- 239000007788 liquid Substances 0.000 claims description 22
- 239000000920 calcium hydroxide Substances 0.000 claims description 20
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 20
- 230000008569 process Effects 0.000 claims description 20
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 18
- 239000006228 supernatant Substances 0.000 claims description 18
- 239000000428 dust Substances 0.000 claims description 17
- 239000001569 carbon dioxide Substances 0.000 claims description 14
- 239000000047 product Substances 0.000 claims description 14
- 238000000108 ultra-filtration Methods 0.000 claims description 13
- 239000002244 precipitate Substances 0.000 claims description 12
- 150000003839 salts Chemical class 0.000 claims description 11
- 238000000926 separation method Methods 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 7
- 238000003756 stirring Methods 0.000 claims description 7
- 208000005156 Dehydration Diseases 0.000 claims description 4
- 230000018044 dehydration Effects 0.000 claims description 4
- 238000006297 dehydration reaction Methods 0.000 claims description 4
- 238000001816 cooling Methods 0.000 claims description 2
- 238000004065 wastewater treatment Methods 0.000 abstract description 13
- 229910052799 carbon Inorganic materials 0.000 abstract description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 7
- 238000005265 energy consumption Methods 0.000 abstract description 6
- 235000011116 calcium hydroxide Nutrition 0.000 description 14
- 238000001223 reverse osmosis Methods 0.000 description 11
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 7
- 229910001425 magnesium ion Inorganic materials 0.000 description 7
- 229910001424 calcium ion Inorganic materials 0.000 description 6
- 239000011575 calcium Substances 0.000 description 5
- 238000007599 discharging Methods 0.000 description 5
- 239000004571 lime Substances 0.000 description 4
- 238000004062 sedimentation Methods 0.000 description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 3
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 3
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 3
- 235000019738 Limestone Nutrition 0.000 description 3
- 235000011941 Tilia x europaea Nutrition 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 239000003814 drug Substances 0.000 description 3
- 239000006028 limestone Substances 0.000 description 3
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 3
- 239000000347 magnesium hydroxide Substances 0.000 description 3
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 3
- 230000014759 maintenance of location Effects 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 2
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000003344 environmental pollutant Substances 0.000 description 2
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 2
- 231100000719 pollutant Toxicity 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 description 1
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- 229910052925 anhydrite Inorganic materials 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 229910000020 calcium bicarbonate Inorganic materials 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 239000003456 ion exchange resin Substances 0.000 description 1
- 229920003303 ion-exchange polymer Polymers 0.000 description 1
- 235000012204 lemonade/lime carbonate Nutrition 0.000 description 1
- 229910000022 magnesium bicarbonate Inorganic materials 0.000 description 1
- 229910001629 magnesium chloride Inorganic materials 0.000 description 1
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 230000005070 ripening Effects 0.000 description 1
- 239000013049 sediment Substances 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
Images
Classifications
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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
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2/00—Lime, magnesia or dolomite
- C04B2/02—Lime
- C04B2/04—Slaking
- C04B2/08—Devices therefor
-
- 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
- C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
-
- 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
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
-
- 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
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
-
- 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
- C02F1/5281—Installations for water purification using chemical agents
-
- 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
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/02—Temperature
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/07—Alkalinity
-
- 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
- C02F2303/22—Eliminating or preventing deposits, scale removal, scale prevention
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/02—Softening water by precipitation of the hardness
- C02F5/06—Softening water by precipitation of the hardness using calcium compounds
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Ceramic Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention discloses a system and a method for treating wastewater by recycling calcium carbonate. This cyclic utilization calcium carbonate treatment wastewater system includes softening installation, deposits device, clarification device, sludge dewatering device, filter equipment, membrane enrichment facility, calcium carbonate calcining device, calcium oxide curing device and evaporation crystallization device, softening installation, precipitation device, clarification device, filter equipment, membrane enrichment facility and evaporation crystallization device connect gradually, sludge dewatering device with it connects to deposit the device, calcium oxide curing device with softening installation connects, calcium carbonate calcining device respectively with sludge dewatering mechanism with clarification device calcium oxide curing device connects. The calcium carbonate recycling wastewater treatment system can reduce system energy consumption, reduce carbon emission, effectively recycle sludge, reduce system operation cost and realize recycling of wastewater treatment resources.
Description
Technical Field
The invention relates to the field of water treatment, in particular to a system and a method for treating wastewater by recycling calcium carbonate.
Background
At present, the industry in northwest areas develops rapidly, a large amount of industrial wastewater is generated in various industrial production, and the wastewater is subjected to early reverse osmosis concentration treatment or circulating cooling water evaporation to cause the concentration of inorganic salts and organic matters in the wastewater. Particularly, the increase of calcium and magnesium ions and alkalinity is remarkable, and the reduction is required to be within a limit value range no matter which treatment process is adopted subsequently. At present, zero-emission treatment process is advocated vigorously in the field of environmental protection, so an evaporative crystallization system becomes an essential workshop section in the water treatment industry.
The main treatment process for removing high hardness and high alkalinity in water at the present stage comprises the following steps: the lime softening method is characterized in that lime and sodium carbonate are added into the wastewater to remove calcium and magnesium ions, but the generated precipitation amount is large, a dosing pipeline and a sedimentation tank are easy to block, and the treatment cost and the maintenance cost are high; and secondly, the ion exchange resin reduces the content of calcium and magnesium ions in water through replacement, but the regeneration is frequent and the investment cost is high.
In addition, the pretreated wastewater enters an evaporative crystallization system through concentration salt separation, wherein the heat source of the evaporative crystallization system mainly comprises steam and electric power, and the heat source of the evaporative crystallization system is a main component of the operation cost of the evaporative crystallization system and accounts for 50-65% of the total cost, so that the cost of the existing treatment method is high.
Disclosure of Invention
Based on the above, there is a need for a system and a method for treating wastewater by recycling calcium carbonate, which can reduce energy consumption of the system, reduce carbon emission, effectively recycle sludge, reduce operation cost of the system, and realize resource recycling of wastewater treatment.
The utility model provides a cyclic utilization calcium carbonate treatment wastewater system, includes softening installation, deposits device, clarification device, sludge dewatering device, filter equipment, membrane enrichment facility, calcium carbonate calcining device, calcium oxide curing device and evaporation crystallization device, softening installation, precipitation device, clarification device, filter equipment, membrane enrichment facility and evaporation crystallization device connect gradually in proper order, sludge dewatering device with it connects to deposit the device, calcium oxide curing device with softening installation connects, calcium carbonate calcining device respectively with sludge dewatering mechanism with clarification device calcium oxide curing device connects.
In one embodiment, the system for recycling calcium carbonate to treat wastewater further comprises a water production device, and the water production device is connected with the membrane concentration device.
In one embodiment, the water producing device is further connected with the calcium oxide curing device for calcium oxide curing.
In one embodiment, the calcium carbonate calcining device comprises a calcium carbonate calcining furnace and a cyclone dust collector, the calcium carbonate calcining furnace is connected with the clarifying device through the cyclone dust collector, and the cyclone dust collector is used for collecting CO generated in the calcining process of the calcium carbonate calcining furnace2And is conveyed to the clarifying device after dust removal.
In one embodiment, the system for recycling calcium carbonate to treat wastewater further comprises a finished product bin, the finished product bin is connected with the calcium carbonate calcining device, and calcium oxide generated by calcining of the calcium carbonate calcining device enters the finished product bin after being cooled.
In one embodiment, the system for recycling calcium carbonate to treat wastewater further comprises a heat collector, wherein the heat collector is arranged on the calcium oxide curing device and is used for collecting heat generated by calcium oxide curing and transmitting the heat to the evaporative crystallization device.
In one embodiment, the filtration device is an ultrafiltration module.
A method for recycling calcium carbonate to treat wastewater comprises the following steps:
the high-hardness and high-alkalinity wastewater enters a softening device, calcium hydroxide solution with the concentration of 3-6% is added into the softening device, and stirring reaction is carried out to form turbid liquid; the turbid liquid enters a precipitation device for precipitation, solid-liquid separation is realized to form precipitate and supernatant, and the precipitate enters a sludge dehydration device for dehydration treatment to obtain sludge;
the supernatant enters a clarifying device, carbon dioxide is introduced into the clarifying device to adjust the pH value to a preset range, and then the supernatant enters a filtering device to carry out solid-liquid deep separation and partial COD removal;
the sludge generated by the sludge dewatering device is conveyed to a calcium carbonate calcining device for calcining, and CO generated by calcining of the calcium carbonate calcining device2Conveying the calcined calcium oxide into the clarifying device, cooling the calcined calcium oxide, and then conveying the cooled calcium oxide into a calcium oxide curing system;
calcium oxide generated by a calcium carbonate calcining device enters a calcium oxide curing device, the calcium oxide and water are cured to release heat to generate calcium hydroxide, heat generated by the calcium carbonate calcining device is collected by a heat collector and then is transmitted to an evaporative crystallization device, and the calcium hydroxide generated by the calcium oxide curing device is transmitted to a softening device;
the effluent of the filtering device enters a membrane concentration device for concentration; and the water produced by the membrane concentration device enters the calcium oxide curing device for calcium oxide curing, the concentrated water of the membrane concentration device enters the evaporation crystallization device, and the evaporation crystallization device evaporates the concentrated water to produce crystallized salt.
In one embodiment, the water content of the dewatered sludge is 65-75%.
In one embodiment, the mass ratio of the calcium oxide to the water in the calcium oxide ripening apparatus is from 1:3.5 to 1: 5.
In one embodiment, the filtration device has an effluent turbidity of less than 2 NTU.
In one of the embodimentsThe calcium carbonate calcining device calcines the generated CO2And the dust is collected and removed by a cyclone dust collector and then is conveyed to the clarifying device.
The calcium carbonate wastewater treatment system can reduce the energy consumption of the system, reduce the carbon emission, effectively recycle the sludge, reduce the operation cost of the system and realize the resource recycling of wastewater treatment.
The method for treating wastewater by using calcium carbonate has the following beneficial effects:
1. the evaporative crystallization device does not need electric power or a steam stripping heat supply source, the running cost of the whole evaporative crystallization device is reduced by 80-95%, and the energy consumption of the whole calcium carbonate treatment wastewater system is reduced by 70%.
2. The softening device generates a large amount of sludge such as calcium carbonate to be recycled, and the process for treating wastewater by recycling calcium carbonate avoids the problem of higher operation cost caused by excessive addition of medicament on one hand and reduces the treatment cost of sludge on the other hand; compared with the traditional process, the method for treating the wastewater by using the calcium carbonate only adds a calcium carbonate calcining device and a calcium oxide curing device, and the investment cost is obviously reduced.
3. The method for treating wastewater by using calcium carbonate has the advantages that the heat generated by the aged lime has no secondary pollution, the effective recycling is realized, the carbon emission is reduced, the pH is adjusted by using the carbon dioxide recovery, and the system operation cost is reduced.
4. The method for treating wastewater by using calcium carbonate realizes effective recycling of sludge and reduces the operation cost of the system.
5. The calcium carbonate wastewater treatment method disclosed by the invention has no discharge of pollutants such as sludge and waste liquid in the whole process, and completely realizes resource recycling of wastewater treatment.
Drawings
FIG. 1 is a process flow diagram of a system for recycling calcium carbonate to treat wastewater according to an embodiment of the present invention;
FIG. 2 is a schematic view of a system for recycling calcium carbonate to treat wastewater according to an embodiment of the present invention.
10. A wastewater treatment system for recycling calcium carbonate; 100. a softening device; 101. a softening tank; 102. softening the stirrer; 200. a precipitation device; 201. a sedimentation tank; 202. a sludge pump; 300. a clarification device; 301. a clarification tank; 302. a clarifying stirrer; 400. a sludge dewatering device; 401. a plate-and-frame filter press; 402. a plate frame discharging pump; 500. a filtration device; 501. an ultrafiltration water intake pump; 502. an ultrafiltration membrane device; 503. an ultrafiltration water-producing tank; 600. a membrane concentration device; 601. high-pressure reverse osmosis; 602. a membrane concentration water inlet pump; 700. a calcium carbonate calcining device; 701. a calcium carbonate calcining furnace; 702. a cyclone dust collector; 800. a calcium oxide curing device; 801. a curing water inlet pump; 802. a curing device; 803. a limestone feed pump; 900. an evaporative crystallization device; 901. an evaporative heat exchanger; 902. an evaporation circulating pump; 1000. a water producing device.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
In the description of the present invention, it should be understood that the terms used in the present invention are used in the description of the present invention, and it should be understood that the directions or positional relationships indicated by the terms "center", "upper", "lower", "bottom", "inner", "outer", etc. in the present invention are based on the directions or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.
It should be understood that the terms "first", "second", etc. are used herein to describe various information, but the information should not be limited to these terms, which are only used to distinguish one type of information from another. For example, "first" information may also be referred to as "second" information, and similarly, "second" information may also be referred to as "first" information, without departing from the scope of the present invention.
In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "connected" and "connected" are to be interpreted broadly, e.g., as being fixed or detachable or integrally connected; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening elements, or they may be in communication within two elements, i.e., when an element is referred to as being "secured to" another element, it may be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Referring to FIG. 1, one embodiment of the present invention provides a system 10 for recycling calcium carbonate to treat wastewater. The system 10 for recycling calcium carbonate to treat wastewater comprises a softening device 100, a precipitation device 200, a clarification device 300, a sludge dewatering device 400, a filtering device 500, a membrane concentration device 600, a calcium carbonate calcining device 700, a calcium oxide curing device 800 and an evaporation crystallization device 900. The softening device 100, the precipitation device 200, the clarification device 300, the filtering device 500, the membrane concentration device 600 and the evaporation crystallization device 900 are sequentially connected, the sludge dewatering device 400 is connected with the precipitation device 200, the calcium oxide curing device 800 is connected with the softening device 100, and the calcium carbonate calcining device 700 is respectively connected with the clarification device 300, the sludge dewatering mechanism 400 and the calcium oxide curing device 800.
In one particular example, the system 10 for recycling calcium carbonate to treat wastewater further includes a water producing device 1000. The water producing apparatus 1000 is connected to the membrane concentration apparatus 600.
In one particular example, the water producing device 1000 is also connected to a calcium oxide slaking device 800 for calcium oxide slaking.
In one particular example, the system 10 for recycling calcium carbonate to treat wastewater further includes a sludge dewatering discharge pump and a vibratory feeder. The sludge dewatering device 400 is connected with the calcium carbonate calcining device 700 through a sludge dewatering discharge pump and a vibrating feeder.
In one particular example, the calcium carbonate calcining apparatus 700 includes a calcium carbonate calcining furnace 701 and a cyclone 702. The calcium carbonate calcining furnace 701 is connected with the clarifying device 300 through a cyclone 702, and the cyclone 702 is used for collecting CO generated in the calcining process of the calcium carbonate calcining furnace 7012And is transported to the clarifying apparatus 300 after dust removal.
In a specific example, the system 10 for recycling calcium carbonate to treat wastewater further comprises a finished product bin, the finished product bin is connected with the calcium carbonate calcining device 700, and calcium oxide generated by calcining in the calcium carbonate calcining device 700 enters the finished product bin after being cooled.
In one specific example, the system 10 for recycling calcium carbonate to treat wastewater further comprises an ash discharge conveying device connected between the finished product bin and the calcium oxide curing device 800, wherein a part of calcium oxide in the finished product bin is conveyed into the calcium oxide curing device 800 through the ash discharge conveying device, and a part of calcium oxide is packaged and sold.
In one specific example, the system 10 for recycling calcium carbonate to treat wastewater further comprises a heat collector disposed on the calcium oxide slaking apparatus 800, the heat collector is used for collecting heat generated by slaking calcium oxide and transferring the heat to the evaporative crystallization apparatus 900.
In one particular example, the filtration device 500 is an ultrafiltration module.
Referring to FIG. 2, in another embodiment, the softening unit 100 includes a softening tank 101 and a softening blender 102 disposed within the softening tank 101.
The settling device 200 includes a settling tank 201 and a sludge pump 202 disposed in the settling tank 201.
The clarification device 300 includes a clarifier 301 and a clarification blender 302 disposed within the clarifier 301.
The filtering device 500 comprises an ultrafiltration water inlet pump 501, an ultrafiltration membrane device 502 and an ultrafiltration water generating tank 503 which are sequentially communicated.
The membrane concentration device 600 includes a high pressure reverse osmosis 601 and a membrane concentration feed pump 602.
Specifically, the evaporative crystallization apparatus 900 includes an evaporative heat exchanger 901 and an evaporative circulation pump 902.
The softening tank 101, the sedimentation tank 201, the clarification tank 301, an ultrafiltration water inlet pump 501, an ultrafiltration membrane device 502, an ultrafiltration water production tank 503, a membrane concentration water inlet pump 602, a high-pressure reverse osmosis 601, an evaporation circulating pump 902 and an evaporation heat exchanger 901 are sequentially connected.
Further, the sludge dewatering device 400 comprises a plate-and-frame filter press 401 and a plate-and-frame discharge pump 402, the plate-and-frame filter press 401 is connected with the precipitation device 200, and the plate-and-frame filter press 401 is also connected with the calcium carbonate calcining furnace 701 of the calcium carbonate calcining device 700 through the plate-and-frame discharge pump 402.
Further, the calcium oxide slaking apparatus 800 includes a slaking water feed pump 801, a slaker 802, and a limestone feed pump 803, the slaker 802 is connected to the water producing apparatus 1000 by the slaking water feed pump 801, and the slaker 802 is connected to the calcium carbonate calcining furnace 701 of the calcium carbonate calcining apparatus 700 by the limestone feed pump 803. An embodiment of the invention provides a method for treating wastewater by recycling calcium carbonate.
The calcium carbonate wastewater treatment system can reduce the energy consumption of the system, reduce the carbon emission, effectively recycle the sludge, reduce the operation cost of the system and realize the resource recycling of wastewater treatment.
A method for recycling calcium carbonate to treat wastewater comprises the following steps:
referring to fig. 1 and 2, the high hardness and high alkalinity wastewater enters a softening device 100, and a calcium hydroxide solution with a concentration of 3-6% is added into the softening device 100 to be stirred and reacted to form a turbid solution; the stirring reaction time is 10-20min, and the stirring speed is 100-120 rpm.
The working principle of the softening device 100, i.e. the reaction equation, is as follows:
Ca(OH)2+Ca(HCO3)2=2CaCO3↓+2H2O;
2Ca(OH)2+Mg(HCO3)2=2CaCO3↓+Mg(OH)2↓+2H2O;
MgSO4+Ca(OH)2=CaSO4↓+Mg(OH)2↓;
MgCl2+Ca(OH)2=CaCl2↓+Mg(OH)2↓。
the turbid liquid enters the precipitation device 200 through an overflow port for precipitation to realize solid-liquid separation to form precipitate and supernatant, the retention time of the precipitation device 200 is 45min, the precipitate enters the sludge dewatering device 400 through the sludge pump 202 for dewatering treatment to obtain sludge, the water content of the sludge after dewatering is 65-75%, for example, the water content of the sludge after dewatering is 65%, 68%, 70%, 75% or other numerical values.
The supernatant enters the clarifying device 300 through an overflow port, carbon dioxide is introduced into the clarifying device 300 to adjust the pH value to a preset range, and the supernatant enters the filtering device 500 through a water inlet pump of the filtering device 500 to carry out solid-liquid deep separation and partial removal of COD. The carbon dioxide is introduced into the clarifying device 300 to adjust the pH value to a predetermined range of pH value 7.0-8.3. The principle of introducing carbon dioxide into the clarification device 300 to adjust the pH value is as follows:
carbon dioxide is passed to a clarification device 300 to adjust the pH and remove suspended matter by filtration:
CO2+H2O=H2CO3;
CO2+OH-=HCO3 -。
the sludge (main component calcium carbonate) with the water content of 65-75 percent generated by the sludge dewatering device 400 is conveyed to a vibration feeder of the calcium carbonate calcining device 700 by a belt conveyor and then enters a calcining furnace of the calcium carbonate calcining device 700 for calcining, and carbon is obtainedThe calcination temperature of the calcium carbonate calcination apparatus 700 is 600-700 deg.C, such as 600 deg.C, 650 deg.C, 700 deg.C or other values for the calcination temperature of the calcium carbonate calcination apparatus 700. CO produced by calcination2Enters a cyclone dust collector 702 to be collected and conveyed to a clarifying device 300, and after calcium oxide generated by calcination is cooled, the calcium oxide enters a finished product bin and then is conveyed to a calcium oxide curing system through an ash discharging conveying device.
The calcium oxide generated by the calcium carbonate calcining device 700 enters the calcium oxide curing device 800, and the mass ratio of the calcium oxide to the water in the calcium oxide curing device 800 is 1:3.5-1:5, for example, the mass ratio of the calcium oxide to the water in the calcium oxide curing device 800 is 1:3.5, 1:4, 1:5 or other ratios.
Heating calcium carbonate to 370 c by the calcium carbonate calcination apparatus 700 decomposes calcium carbonate into calcium oxide and carbon dioxide. The reaction equation is as follows:
CaCO3→CaO+CO2↑。
calcium oxide and water are subjected to curing and heat release to generate calcium hydroxide, heat generated by the calcium carbonate calcining device 700 is collected by a heat collector and transmitted to the evaporative crystallization device 900, and the calcium hydroxide generated by the calcium oxide curing device 800 is transmitted to the softening device 100.
The slaking reaction of calcium oxide and water is as follows:
CaO+H2O→Ca(OH)2。
the effluent of the filtering device 500 directly enters the membrane concentration device 600 through a water inlet pump of the membrane concentration device 600, the turbidity of the effluent of the filtering device 500 is less than 2NTU, and the effluent is subjected to middle-high pressure reverse osmosis concentration TDS to be not less than 170000mg/L, which can only be set as required; the water produced by the membrane concentration device 600 enters the water production device 1000 and then enters the calcium oxide curing device 800 for calcium oxide curing, the concentrated water of the membrane concentration device 600 enters the evaporation crystallization device 900, the evaporation crystallization device 900 evaporates the concentrated water to generate crystal salt, the evaporation heat source of the evaporation crystallization device 900 comes from the heat generated by the calcium oxide curing device 800, and the evaporation temperature of the evaporation crystallization device 900 is 140-160 ℃.
The method for treating wastewater by using calcium carbonate has the following beneficial effects:
1. the evaporative crystallization device 900 does not need electric power or a steam stripping heat supply source, reduces the running cost of the whole evaporative crystallization device 90080-95%, and reduces the energy consumption of the whole calcium carbonate treatment wastewater system by 70%.
2. The softening device 100 generates a large amount of sludge such as calcium carbonate for repeated utilization, and the process for treating wastewater by recycling calcium carbonate avoids the problem of higher operation cost caused by excessive addition of medicament on one hand, and reduces the treatment cost of sludge on the other hand.
3. The method for treating wastewater by using calcium carbonate has the advantages that the heat generated by the aged lime has no secondary pollution, the effective recycling is realized, the carbon emission is reduced, the pH is adjusted by using the carbon dioxide recovery, and the system operation cost is reduced.
4. The method for treating wastewater by using calcium carbonate realizes effective recycling of sludge and reduces the operation cost of the system.
5. The calcium carbonate wastewater treatment method disclosed by the invention has no discharge of pollutants such as sludge and waste liquid in the whole process, and completely realizes resource recycling of wastewater treatment.
Example 1
The embodiment provides a method for treating wastewater by recycling calcium carbonate.
A method for recycling calcium carbonate to treat wastewater comprises the following steps:
referring to fig. 1 and 2, the high hardness and high alkalinity wastewater enters a softening device 100, and a calcium hydroxide solution with a concentration of 3-6% is added into the softening device 100 to be stirred and reacted to form a turbid solution; the reaction time was stirred for 10min at a stirring speed of 100 rpm.
The turbid liquid enters the precipitation device 200 through an overflow port for precipitation, solid-liquid separation is realized to form precipitate and supernatant, the retention time of the precipitation device 200 is 45min, the precipitate enters the sludge dewatering device 400 through the sludge pump 202 for dewatering treatment to obtain sludge, and the water content of the sludge after dewatering is 65-75%.
The supernatant enters the clarifying device 300 through an overflow port, carbon dioxide is introduced into the clarifying device 300 to adjust the pH value to 7.0-8.3, the supernatant enters the filtering device 500 through a water inlet pump of the filtering device 500 to carry out solid-liquid deep separation and partial removal of COD, and the turbidity of the effluent of the clarifying device 300 is less than 2 NT.
The sludge (main component calcium carbonate) with the water content of 65-75 percent generated by the sludge dewatering device 400 is conveyed to a vibration feeder of a calcium carbonate calcining device 700 through a belt conveyor and then enters a calcining furnace of the calcium carbonate calcining device 700 for calcining, the calcining temperature of the calcium carbonate calcining device 700 is 600 ℃, and CO generated by calcining is calcined2The calcium oxide enters a cyclone dust collector 702 to be collected and conveyed to a clarifying device 300, after the calcium oxide generated by calcination is cooled and enters a finished product bin, a part of the calcium oxide is conveyed to a calcium oxide curing device 800 through an ash discharging conveying device, and a part of the calcium oxide is packaged and sold.
Calcium oxide generated by the calcium carbonate calcining device 700 enters the calcium oxide curing device 800, the calcium oxide and water in the calcium oxide curing device 800 are cured and released to generate calcium hydroxide, the heat generated by the calcium carbonate calcining device 700 is collected by a heat collector and then transmitted to the evaporative crystallization device 900, and the calcium hydroxide generated by the calcium oxide curing device 800 is transmitted to the softening device 100.
The effluent of the filtering device 500 directly enters the membrane concentration device 600 through a water inlet pump of the membrane concentration device 600, the turbidity of the effluent of the filtering device 500 is less than 2NTU, and the TDS is concentrated to 170000mg/L by medium-high pressure reverse osmosis; the water produced by the membrane concentration device 600 enters the water production device 1000 and then enters the calcium oxide curing device 800 for calcium oxide curing, and the redundant produced water reaches the standard and is discharged or recycled. The concentrated water of the membrane concentration device 600 enters the evaporation crystallization device 900, the evaporation crystallization device 900 evaporates the concentrated water to generate crystallized salt, the evaporation heat source of the evaporation crystallization device 900 comes from the heat generated by the calcium oxide curing device 800, and the evaporation temperature of the evaporation crystallization device 900 is 150 ℃.
In the embodiment, after the treatment, hardness and alkalinity in the wastewater are basically removed by adding calcium hydroxide, carbon dioxide generated by calcining the generated calcium carbonate precipitate is used for adjusting the pH of the supernatant in the clarifying device 300, heat generated by heat release and curing is introduced into the calcined calcium oxide, the heat is collected and used as a heat source of the evaporative crystallization device 900, then the generated calcium hydroxide feed liquid is added into a softening system to remove the alkalinity and hardness, concentrated water after membrane concentration enters the evaporative crystallization device 900 to generate crystallized salt, finally the whole process is recycled, and no wastewater or sludge is discharged in the process.
Example 2
The method for treating wastewater by recycling calcium carbonate in example 1 is used for treating high-hardness and high-alkalinity wastewater of a chemical industry enterprise, and specifically comprises the following steps:
the water quality condition of high-hardness and high-alkalinity wastewater combined with a certain chemical enterprise is as follows: 13000mg/L, Ca TDS2+=750mg/L、Mg2+45mg/L, 1500mg/L, Na total alkalinity+=25106.9mg/L、Cl-=112240.4mg/L、SO4 2-=364.1mg/L。
Referring to fig. 1 and 2, the high hardness and high alkalinity wastewater enters the softening device 100, and the volume of the softening device 100 is 3m3The inflow rate is 10m3And h, adding a 3% calcium hydroxide solution into the softening device 100 to control the pH value of the high-hardness and high-alkalinity wastewater to be 10.8-11.2, and stirring for reaction for 10min at a stirring speed of 100rpm to form a turbid solution.
The turbid liquid enters the precipitation device 200 through an overflow port for precipitation to realize solid-liquid separation to form precipitate and supernatant, and the volume of the turbid liquid entering the precipitation device 200 is 10m3The residence time of the sedimentation device 200 is 45min, the sediment enters the sludge dewatering device 400 through the sludge pump 202 to be dewatered to obtain sludge, the sludge enters the filter press to be filter-pressed and dewatered, the water content of the sludge after dewatering is 65-75%, the processing capacity of the filter press is 1.2t/h, the working pressure is 1.5MPa, and the filtering area is 60m2CaCO, dewatered sludge3The content is more than or equal to 95 percent.
The supernatant enters a clarifying device 300 through an overflow port, carbon dioxide is introduced into the clarifying device 300 to adjust the pH value to 8.3-7.0, the mixture is stirred at the speed of 150rpm, and the volume of the clarifying device 300 is 5m3The retention time of the supernatant in the clarifying device 300 was 1.5h, and the pH of the clarified supernatant was 8.0 and Ca2+:42.5mg/L、Mg2+: 1.3mg/L and 5NTU turbidity, and the clarified supernatant enters the filter device 500 through the water inlet pump of the filter device 500 for solid-liquid deep separation and partial COD removal.
The sludge (calcium carbonate) with the water content of 65-75% generated by the sludge dewatering device 400 is conveyed to a vibration feeder of a calcium carbonate calcining device 700 through a belt conveyor and then enters a calcining furnace of the calcium carbonate calcining device 700 for calcining, the calcining temperature of the calcium carbonate calcining device 700 is 600 +/-30 ℃ for 45min, the reaction efficiency is more than 95%, and CO is generated2The purity was 85% at 3.3kg/h, and CaO was produced at 4.2kg/h and the purity was 95% or more. CO produced by calcination2Enters a cyclone dust collector 702 to be collected and conveyed to a clarifying device 300, and after calcium oxide generated by calcination is cooled, the calcium oxide enters a finished product bin and then is conveyed to a calcium oxide curing system through an ash discharging conveying device.
Calcium oxide generated by the calcium carbonate calcining device 700 enters the calcium oxide curing device 800, the calcium oxide and water in the calcium oxide curing device 800 are cured and released to generate calcium hydroxide, the heat generated by the calcium carbonate calcining device 700 is collected by a heat collector and then transmitted to the evaporative crystallization device 900, and the calcium hydroxide generated by the calcium oxide curing device 800 is transmitted to the softening device 100.
The filtering apparatus 500 is provided with 6 effective membranes 77m2The ultrafiltration concentrated water of the filter device 500 flows back to the clarifying device 300, the effluent of the filter device 500 directly enters the membrane concentration device 600 through the water inlet pump of the membrane concentration device 600, the turbidity of the effluent of the filter device 500 is less than 0.5NTU, and the TDS is concentrated to 170000mg/L by medium-high pressure reverse osmosis; when the medium-high pressure reverse osmosis is concentrated, the medium-high pressure reverse osmosis has 18 membranes and the operating pressure is 4.5MPa, the high pressure reverse osmosis has 4 membranes and the operating pressure is 12MPa, and the recovery rate of the medium-high pressure reverse osmosis is 85 percent.
The water produced by the membrane concentration device 600 enters the water production device 1000, and the volume of the water production device 1000 is 25m2The pH value of the produced water is 6-9 and Ca2+:10mg/L、Mg2+: 2mg/L, TDS is 1000mg/L, the water produced in the water producing device 1000 enters the calcium oxide curing device 800 for calcium oxide curing, and the redundant water reaches the standardAnd (4) discharging or recycling. 1kg of calcium oxide reacts with the produced water to release 1160J heat, the produced steam 477.69kg enters an evaporative crystallization device 900, the curing speed is 5.55kg/h, and Ca (OH) is produced by curing2Into the softening unit 100.
The concentrated water with the TDS of 170000mg/L of the membrane concentration device 600 enters the evaporation crystallization device 900, the evaporation crystallization device 900 evaporates the concentrated water to generate crystal salt, and the heat exchange area of the evaporation crystallization device 900 is 150m2Diameter of forced circulation evaporator of evaporative crystallization apparatus 900 is 3.8m2The diameter of the crystallizer of the evaporative crystallization apparatus 900 is 3.8m2To give a crystalline salt of 0.25m2H is used as the reference value. The evaporation heat source of the evaporative crystallization device 900 is derived from the heat generated by the calcium oxide slaking device 800, and the evaporation temperature of the evaporative crystallization device 900 is 150 ℃.
In the embodiment, a large amount of calcium carbonate sludge generated by the softening device 100 is recycled, and a comparison between table 1 and table 2 shows that the method for treating wastewater by recycling calcium carbonate in the embodiment avoids the problem of high operation cost caused by excessive addition of a medicament on one hand, and reduces the treatment cost of sludge on the other hand. Compared with the traditional process, the calcium carbonate wastewater treatment method only adds the calcium carbonate calcining device 700 and the calcium oxide curing device 800, the investment cost is only increased by about 15-20 ten thousand yuan, but the annual treatment cost is lower than that of the traditional process by about 27.02 ten thousand yuan, and the cost is relatively obviously reduced.
Table 1: running cost of traditional process
Table 2: example 2 method for treating wastewater by recycling calcium carbonate
This implementationExample mainly for TDS 13000mg/L, Ca2+=750mg/L、Mg2+The high hardness and high alkalinity waste water with total alkalinity of 45mg/L and 1500mg/L is treated through adding slaked lime (Ca (OH) into the softening apparatus 1002) The water is removed hardness and alkalinity, and then enters the filtering device 500 to remove suspended matters and part of COD, and then enters the membrane concentration device 600 to further concentrate various components and separate components by a membrane method, and then enters the evaporation crystallization device 900 to be evaporated to generate crystallized salt. The heat energy required by the evaporation crystallization device 900 enters the calcium carbonate calcination device 700 through the calcium carbonate precipitate generated by the device 100 to be calcined to generate calcium oxide, the calcium oxide enters the calcium oxide curing device 800 to react with water to generate a large amount of heat to be used as a heat source of the evaporation crystallization device 900, the energy is recycled, and carbon dioxide generated in the calcination process enters the clarification device 300 to adjust the pH value. The slaked lime produced by the calcium oxide slaking device 800 is returned to the softening device 100 to be added as a hardness removing agent. After the treatment method, the hardness and alkalinity in the wastewater are basically removed by adding calcium hydroxide, the generated carbon dioxide generated by calcining the calcium carbonate precipitate is used for adjusting the pH value, the calcium oxide generated by calcining is introduced into heat generated by heat release curing and collected to be used as a heat source of the evaporative crystallization device 900, the generated calcium hydroxide feed liquid is added into the softening device 100 for removing the alkalinity and the hardness, the concentrated water after membrane concentration enters the evaporative crystallization device 900 to generate crystal salt, finally the whole process realizes cyclic utilization, and no wastewater or sludge is discharged in the process.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (12)
1. The utility model provides a cyclic utilization calcium carbonate treatment wastewater system, its characterized in that, includes softening installation, deposits device, clarification device, sludge dewatering device, filter equipment, membrane enrichment facility, calcium carbonate calcining device, calcium oxide curing device and evaporation crystallization device, softening installation, precipitation device, clarification device, filter equipment, membrane enrichment facility and evaporation crystallization device connect gradually in proper order, sludge dewatering device with it connects to deposit the device, calcium oxide curing device with softening installation connects, calcium carbonate calcining device respectively with sludge dewatering mechanism with clarification device calcium oxide curing device connects.
2. The system for recycling calcium carbonate-treated wastewater according to claim 1, further comprising a water-producing device connected to the membrane concentration device.
3. The system for recycling calcium carbonate wastewater according to claim 2, wherein the water production device is further connected to the calcium oxide slaking device for slaking calcium oxide.
4. The system for recycling calcium carbonate to treat wastewater as claimed in any one of claims 1 to 3, wherein the calcium carbonate calcining device comprises a calcium carbonate calcining furnace and a cyclone dust collector, the calcium carbonate calcining furnace is connected with the clarifying device through the cyclone dust collector, and the cyclone dust collector is used for collecting CO generated in the calcining process of the calcium carbonate calcining furnace2And is conveyed to the clarifying device after dust removal.
5. The system for recycling calcium carbonate to treat wastewater according to any one of claims 1 to 3, further comprising a finished product bin, wherein the finished product bin is connected with the calcium carbonate calcining device, and calcium oxide generated by calcining of the calcium carbonate calcining device enters the finished product bin after being cooled.
6. The system for recycling calcium carbonate wastewater according to any one of claims 1 to 3, further comprising a heat collector disposed on the calcium oxide slaking device, wherein the heat collector is used for collecting heat generated by slaking the calcium oxide and transferring the heat to the evaporative crystallization device.
7. The system for recycling calcium carbonate wastewater according to any one of claims 1 to 3, wherein the filtration device is an ultrafiltration module.
8. A method for recycling calcium carbonate to treat wastewater is characterized by comprising the following steps:
the high-hardness and high-alkalinity wastewater enters a softening device, calcium hydroxide solution with the concentration of 3-6% is added into the softening device, and stirring reaction is carried out to form turbid liquid; the turbid liquid enters a precipitation device for precipitation, solid-liquid separation is realized to form precipitate and supernatant, and the precipitate enters a sludge dehydration device for dehydration treatment to obtain sludge;
the supernatant enters a clarifying device, carbon dioxide is introduced into the clarifying device to adjust the pH value to a preset range, and then the supernatant enters a filtering device to carry out solid-liquid deep separation and partial COD removal;
the sludge generated by the sludge dewatering device is conveyed to a calcium carbonate calcining device for calcining, and CO generated by calcining of the calcium carbonate calcining device2Conveying the calcined calcium oxide into the clarifying device, cooling the calcined calcium oxide, and then conveying the cooled calcium oxide into a calcium oxide curing system;
calcium oxide generated by a calcium carbonate calcining device enters a calcium oxide curing device, the calcium oxide and water are cured to release heat to generate calcium hydroxide, heat generated by the calcium carbonate calcining device is collected by a heat collector and then is transmitted to an evaporative crystallization device, and the calcium hydroxide generated by the calcium oxide curing device is transmitted to a softening device;
the effluent of the filtering device enters a membrane concentration device for concentration; and the water produced by the membrane concentration device enters the calcium oxide curing device for calcium oxide curing, the concentrated water of the membrane concentration device enters the evaporation crystallization device, and the evaporation crystallization device evaporates the concentrated water to produce crystallized salt.
9. The method for recycling calcium carbonate to treat wastewater according to claim 8, wherein the water content of the dewatered sludge is 65-75%.
10. The method for recycling calcium carbonate to treat wastewater according to claim 8 or 9, wherein the mass ratio of the calcium oxide to the water in the calcium oxide slaking apparatus is 1:3.5 to 1: 5.
11. The method for recycling calcium carbonate to treat wastewater according to claim 8 or 9, wherein the turbidity of the effluent of the filtering device is less than 2 NTU.
12. The method for recycling calcium carbonate wastewater according to claim 8 or 9, wherein the calcium carbonate calcination apparatus calcines CO generated2And the dust is collected and removed by a cyclone dust collector and then is conveyed to the clarifying device.
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