CN113979607A - Treatment method of desulfurization wastewater of coal-fired power plant - Google Patents
Treatment method of desulfurization wastewater of coal-fired power plant Download PDFInfo
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- CN113979607A CN113979607A CN202111469388.6A CN202111469388A CN113979607A CN 113979607 A CN113979607 A CN 113979607A CN 202111469388 A CN202111469388 A CN 202111469388A CN 113979607 A CN113979607 A CN 113979607A
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- 239000002351 wastewater Substances 0.000 title claims abstract description 121
- 238000006477 desulfuration reaction Methods 0.000 title claims abstract description 66
- 230000023556 desulfurization Effects 0.000 title claims abstract description 66
- 238000000034 method Methods 0.000 title claims abstract description 37
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims abstract description 19
- 238000005189 flocculation Methods 0.000 claims abstract description 19
- 230000016615 flocculation Effects 0.000 claims abstract description 19
- 238000003756 stirring Methods 0.000 claims abstract description 18
- 229910001385 heavy metal Inorganic materials 0.000 claims abstract description 17
- 230000007935 neutral effect Effects 0.000 claims abstract description 14
- 239000012528 membrane Substances 0.000 claims abstract description 13
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims abstract description 11
- 235000011941 Tilia x europaea Nutrition 0.000 claims abstract description 11
- 239000004571 lime Substances 0.000 claims abstract description 11
- 239000008267 milk Substances 0.000 claims abstract description 11
- 210000004080 milk Anatomy 0.000 claims abstract description 11
- 235000013336 milk Nutrition 0.000 claims abstract description 11
- 239000008394 flocculating agent Substances 0.000 claims abstract description 8
- 238000004062 sedimentation Methods 0.000 claims abstract description 8
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 7
- 230000001105 regulatory effect Effects 0.000 claims abstract description 3
- 238000001471 micro-filtration Methods 0.000 claims description 16
- 150000002500 ions Chemical class 0.000 claims description 7
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 6
- 230000032770 biofilm formation Effects 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 6
- 239000000945 filler Substances 0.000 claims description 6
- 239000001301 oxygen Substances 0.000 claims description 6
- 229910052760 oxygen Inorganic materials 0.000 claims description 6
- 239000010802 sludge Substances 0.000 claims description 6
- 239000004115 Sodium Silicate Substances 0.000 claims description 5
- 125000002091 cationic group Chemical group 0.000 claims description 5
- 238000013329 compounding Methods 0.000 claims description 5
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 claims description 5
- 229910000360 iron(III) sulfate Inorganic materials 0.000 claims description 5
- 230000014759 maintenance of location Effects 0.000 claims description 5
- 229920002401 polyacrylamide Polymers 0.000 claims description 5
- 229920006395 saturated elastomer Polymers 0.000 claims description 5
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 5
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 5
- 239000007787 solid Substances 0.000 claims description 5
- 230000003311 flocculating effect Effects 0.000 claims description 3
- 238000009776 industrial production Methods 0.000 abstract description 4
- 239000007788 liquid Substances 0.000 description 9
- 239000011347 resin Substances 0.000 description 8
- 229920005989 resin Polymers 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- 239000003344 environmental pollutant Substances 0.000 description 7
- 231100000719 pollutant Toxicity 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 5
- 239000003245 coal Substances 0.000 description 5
- 239000003546 flue gas Substances 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 4
- 239000002253 acid Substances 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 4
- 239000000084 colloidal system Substances 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 238000012856 packing Methods 0.000 description 4
- 239000000701 coagulant Substances 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 229910052602 gypsum Inorganic materials 0.000 description 3
- 239000010440 gypsum Substances 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 238000003908 quality control method Methods 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000011651 chromium Substances 0.000 description 2
- 238000006298 dechlorination reaction Methods 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 2
- 229910052753 mercury Inorganic materials 0.000 description 2
- KMUONIBRACKNSN-UHFFFAOYSA-N potassium dichromate Chemical compound [K+].[K+].[O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O KMUONIBRACKNSN-UHFFFAOYSA-N 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- QLOKJRIVRGCVIM-UHFFFAOYSA-N 1-[(4-methylsulfanylphenyl)methyl]piperazine Chemical compound C1=CC(SC)=CC=C1CN1CCNCC1 QLOKJRIVRGCVIM-UHFFFAOYSA-N 0.000 description 1
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- 229910001424 calcium ion Inorganic materials 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- -1 chlorine ions Chemical class 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000000909 electrodialysis Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 239000011133 lead Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000003541 multi-stage reaction Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000010979 pH adjustment Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
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
- 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
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
-
- 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
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
- C02F1/56—Macromolecular compounds
-
- 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
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
-
- 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
- C02F2101/12—Halogens or halogen-containing compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/20—Heavy metals or heavy metal compounds
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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
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/18—Nature of the water, waste water, sewage or sludge to be treated from the purification of gaseous effluents
-
- 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
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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
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/06—Controlling or monitoring parameters in water treatment pH
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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
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/08—Chemical Oxygen Demand [COD]; Biological Oxygen Demand [BOD]
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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
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/10—Solids, e.g. total solids [TS], total suspended solids [TSS] or volatile solids [VS]
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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
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/29—Chlorine compounds
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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
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/02—Aerobic processes
- C02F3/12—Activated sludge processes
- C02F3/1236—Particular type of activated sludge installations
- C02F3/1268—Membrane bioreactor systems
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- Life Sciences & Earth Sciences (AREA)
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Separation Of Suspended Particles By Flocculating Agents (AREA)
Abstract
A method for treating desulfurization wastewater of a coal-fired power plant comprises the following steps: (1) injecting desulfurization wastewater of a coal-fired power plant into a regulating tank for collection, then injecting the desulfurization wastewater into a wastewater neutralization reaction tank, and adding lime milk to regulate the pH value to obtain neutral wastewater; (2) injecting the neutral wastewater obtained in the step (1) into a flocculation sedimentation tank, stirring, adding a flocculating agent, stirring again for flocculation, naturally settling, and dehydrating to obtain flocculated wastewater; (3) and (3) reacting the flocculated wastewater obtained in the step (2) by using a biofilm reactor, and performing membrane treatment to obtain standard wastewater. The method can simultaneously remove suspended matters, chloride ions and heavy metals in the desulfurization wastewater, reduce COD, realize standard discharge of the wastewater, has low cost and simple operation, and is suitable for industrial production.
Description
Technical Field
The invention relates to a method for treating wastewater, in particular to a method for treating desulfurization wastewater of a coal-fired power plant.
Background
Coal used in coal-fired power plants has large grade difference, harmful substances in coal can be reduced by coal washing, and desulfurization treatment of tail gas generated after coal combustion is still the most mainstream mode. The wet flue gas desulfurization is the only desulfurization mode of large-scale commercial operation at present, however, still can produce a large amount of desulfurization waste water in the wet flue gas desulfurization technology, because the pH value of desulfurization waste water is lower, and contains a large amount of suspended solids, chloride ions and heavy metals, if do not carry out innocent treatment and just directly discharge, undoubtedly can cause huge harm to the environment.
CN110894113A discloses a desulfurization waste water dechlorination treatment method and a desulfurization waste water treatment device, wherein the treatment method comprises the following steps: A. firstly, adding acid into the desulfurization wastewater to adjust the pH value to 0.5-4, and then, feeding the desulfurization wastewater into a stirring chamber of a primary dechlorination reactor to be stirred and mixed with liquid resin; B. b, separating the mixture stirred and mixed in the step A in a separation chamber through the density difference between the desulfurization wastewater and the liquid resin, and adsorbing chloride ions of the separated desulfurization wastewater into the liquid resin; C. the separated liquid resin with chloride ions absorbed enters a liquid resin buffer tank, and the separated desulfurization wastewater enters a stirring chamber of a next-stage reactor for further treatment; D. a, B, C steps are repeated in the treatment process, chloride ions in the desulfurization wastewater after the multi-stage reaction are completely removed or enter the air floatation oil removal device to remove liquid resin dissolved in water on the premise of reaching a set treatment value, the pH value is adjusted to 6-9 before the air floatation oil removal device, the desulfurization wastewater after air floatation treatment and pH adjustment is used as reuse water, and the liquid resin brought out by air bubbles in the air floatation oil removal device is scraped and conveyed into a resin buffer tank through a scraping process. However, in the method, a large amount of acid is consumed by firstly adjusting the desulfurization wastewater to an excessively low pH value, a large amount of alkali is consumed by subsequently treating and returning the wastewater to neutral, and even if the removal rate of chloride ions is high in the method, the removal of important pollutants such as suspended matters and heavy metals is not disclosed, and the industrial popularization is difficult due to the excessively high cost of acid and alkali adjustment.
CN111439883A discloses a coal fired power plant wet flue gas desulfurization waste water decrement zero discharge processing system and method, the method is: 1) after being discharged from a desulfurization system, the desulfurization wastewater is divided into reuse water and concentrated wastewater after being clarified, filtered and subjected to non-softening concentration decrement; 2) recycling the reuse water to a desulfurization slurry absorption tower of the desulfurization system, and carrying out advanced treatment on the concentrated wastewater through a desulfurization wastewater tail end treatment system; 3) a bypass flue is arranged at the front end of the air preheater, and part of flue gas is led out; introducing the concentrated wastewater into a drying tower system of a desulfurization wastewater tail end treatment system, and evaporating and drying the concentrated wastewater in the drying tower system by using the waste heat of flue gas; pollutants dissolved in the wastewater are separated out in a form of crystal salt and transferred to an ash silo, and evaporated water is recycled to a desulfurization system, so that zero discharge of the desulfurization wastewater is finally realized. However, since the core equipment of the non-softening concentration and decrement system is the directional driving electrodialysis device, and the amount of the reuse water is only 3/4 of the total water amount, the equipment investment is large, the treatment capacity is limited, the rest 1/4 concentrated wastewater needs to be treated by means of concentration and evaporation, the heat consumption and the steam amount are huge, the required equipment and the required site are main cost investments, and the content and the removal effect of main pollutants in the reuse water are not disclosed in the method.
CN111847699A discloses a method for preparing calcium carbonate by using wet desulphurization wastewater as a raw material and a method for treating wet desulphurization wastewater, which specifically comprise the following steps: p1, adding an alkaline agent into the desulfurization wastewater as a raw material to adjust the pH value to 10.5-10.8; p2, adding organic sulfide with the content enough to separate mercury out in a precipitation form into the desulfurization wastewater treated by the P1 step, and uniformly mixing; p3, adding a coagulant with the content enough to settle colloidal particles and suspended particles in the desulfurization wastewater treated by the step P2 into the desulfurization wastewater, uniformly mixing, and performing solid-liquid separation to remove precipitated precipitates to obtain pretreated desulfurization wastewater; p4, adding an alkaline agent into the pretreated desulfurization wastewater to adjust the pH value to 11.0-11.5; p5, adding water-soluble carbonate with the content enough to precipitate calcium ions in a precipitate form into the pretreated desulfurization wastewater treated by the P4 step, and uniformly mixing; and P6, adding coagulant with the content enough to settle colloidal particles and suspended particles in the pretreated desulfurization wastewater treated by the step P5 into the pretreated desulfurization wastewater, uniformly mixing, and carrying out solid-liquid separation to obtain the calcium carbonate. However, this method requires the wastewater to be adjusted to a higher alkalinity, and the pH of the original desulfurization wastewater is lower, so a large amount of alkaline agent needs to be added, and finally, the wastewater needs to be adjusted to a neutral state, and a large amount of acid agent needs to be consumed; in addition, various reagents such as organic sulfide, coagulant, carbonate and the like need to be added, so that the reagent cost is high, the operation is complicated, and the effect of removing chloride ions is not disclosed.
Therefore, a method for treating desulfurization wastewater of a coal-fired power plant, which can simultaneously remove suspended matters, chloride ions and heavy metals in the desulfurization wastewater, reduce COD, realize standard discharge of the wastewater, has low cost and is suitable for industrial production, is urgently needed to be found.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the defects in the prior art and provide the method for treating the desulfurization wastewater of the coal-fired power plant, which can simultaneously remove suspended matters, chloride ions and heavy metals in the desulfurization wastewater, reduce COD (chemical oxygen demand), realize standard discharge of the wastewater, has low cost and simple operation and is suitable for industrial production.
The technical scheme adopted by the invention for solving the technical problems is as follows: a method for treating desulfurization wastewater of a coal-fired power plant comprises the following steps:
(1) injecting desulfurization wastewater of a coal-fired power plant into a regulating tank for collection, then injecting the desulfurization wastewater into a wastewater neutralization reaction tank, and adding lime milk to regulate the pH value to obtain neutral wastewater;
(2) injecting the neutral wastewater obtained in the step (1) into a flocculation sedimentation tank, stirring, adding a flocculating agent, stirring again for flocculation, naturally settling, and dehydrating to obtain flocculated wastewater;
(3) and (3) reacting the flocculated wastewater obtained in the step (2) by using a biofilm reactor, and performing membrane treatment to obtain standard wastewater.
Preferably, in the step (1), the pH value of the desulfurization wastewater of the coal-fired power plant is 4.0-6.5, the content of suspended matters is 4500-15000 mg/L, the content of chloride ions is 6000-20000 mg/L, the content of heavy metal ions is 0.2-4.0 mg/L, and the COD is 100-400 mg/L. The heavy metals mainly comprise mercury, cadmium, chromium, lead, nickel, zinc and the like.
Preferably, in the step (1), lime milk is added to adjust the pH value to 6.0-7.8. The purpose of adjusting the pH value is to reduce the pH value of the desulfurization wastewater, thereby facilitating the subsequent flocculation and precipitation.
Preferably, in the step (1), the mass concentration of the lime milk is 28%.
Preferably, in the step (2), the amount of the flocculant is 0.05 to 0.50 times (more preferably 0.06 to 0.20 times) of the amount of the solid suspended matter in the wastewater. The flocculating settling can mainly remove suspended matters such as colloid, large particles and the like and partial heavy metal ions.
Preferably, in the step (2), the flocculating agent is prepared by compounding polyaluminium chloride, polyaluminium ferric sulfate, sodium silicate and cationic polyacrylamide according to a mass ratio of 40: 10-15: 5-9: 1-5. The inorganic flocculant and the organic flocculant are matched for use, so that the synergism of the electric neutralization of the inorganic flocculant and the 'bridge and net catching' of the organic flocculant can be fully exerted.
Preferably, in the step (2), before the flocculant is added, the stirring speed is 60-180 r/min, and the time is 10-30 min.
Preferably, in the step (2), after the flocculating agent is added, the stirring and flocculating speed is 30-90 r/min, and the time is 30-90 min.
Preferably, in the step (2), the natural settling time is 2.0-2.5 h.
Preferably, in the step (3), the saturated dissolved oxygen concentration of the reaction in the biofilm reactor is 0.5-2.5 mg/L, and the hydraulic retention time is 36-90 h (more preferably 50-80 h). Most heavy metal ions can be enriched through the biomembrane reactor, and the COD of the wastewater is reduced.
Preferably, in the step (3), the volume load of the biofilm reactor is 3-5 kg/m3·d。
Preferably, in the step (3), the packing material in the biofilm reactor has a bulk density of 90-120 kg/m3(more preferably 95 to 110 kg/m)3) The specific surface area is 60 to 180m2(more preferably 100 to 140 m)/g2/g）。
Preferably, the amount of the biofilm on the filler is 30-80 mg/g (more preferably 50-72 mg/g), and the thickness of the biofilm is 5-80 μm (more preferably 30-72 μm).
Preferably, in the step (3), the biofilm formation mode of the biofilm reactor adopts the existing sludge discharge and biofilm formation method, and the concentration of the activated sludge is 1000-4000 mg/L.
Preferably, in step (3), the membrane treatment is microfiltration.
Preferably, the operation temperature of the microfiltration is 0-45 ℃ (more preferably 10-30 ℃), the pressure is 0.01-0.20 MPa (more preferably 0.08-0.18 MPa), and the surface flow rate of the microfiltration membrane is 1-3 m/s. The chlorine ions, the small molecular suspended matters and part of heavy metal colloid can be removed by microfiltration.
Preferably, the aperture of the microfiltration membrane is 0.01-0.10 μm.
The concentrated solution obtained by membrane treatment of the method is injected into the flocculation sedimentation tank again for flocculation sedimentation.
The method has the following beneficial effects:
(1) the method can simultaneously remove various pollutants in the desulfurization wastewater, the removal rate of suspended matters is as low as 84mg/L, the removal rate is as high as 99.39%, the removal rate of chloride ions is as low as 361mg/L, the removal rate is as high as 97.71%, the removal rate of heavy metals is as low as 0.2mg/L, the removal rate is as high as 83.33%, the removal rate of COD is as low as 12mg/L, the removal rate is as high as 93.49%, the standard of DL/T997-2020 limestone-gypsum wet desulfurization wastewater quality control index of coal-fired power plant is reached, and the recycling of the desulfurization wastewater is realized;
(2) the method has low cost and simple operation, and is suitable for industrial production.
Detailed Description
The present invention will be further described with reference to the following examples.
1-3 of desulfurization wastewater of a coal-fired power plant used in the embodiment of the invention is from sewage pools of different coal-fired power plants; the mass concentration of the lime milk used in the embodiment of the invention is 28 percent; the biofilm formation mode of the biofilm reactor disclosed by the embodiment of the invention adopts the existing sludge discharge and biofilm formation method, and the concentration of activated sludge is 1000-4000 mg/L; the starting materials or chemicals used in the examples of the present invention are, unless otherwise specified, commercially available in a conventional manner.
Example 1
(1) Will be 10m3Injecting the desulfurization wastewater 1 of the coal-fired power plant into an adjusting tank for collection, then injecting the wastewater into a wastewater neutralization reaction tank, and adding lime milk to adjust the pH value to 6.7 to obtain neutral wastewater;
(2) injecting the neutral wastewater obtained in the step (1) into a flocculation sedimentation tank, stirring for 30min at 60r/min, adding 10kg of flocculant (prepared by compounding polyaluminium chloride, polyaluminium ferric sulfate, sodium silicate and cationic polyacrylamide in a mass ratio of 40:12:5: 2), stirring for flocculation for 60min at 60r/min, naturally settling for 2h, and dehydrating to obtain flocculation wastewater;
(3) the flocculated wastewater obtained in the step (2) is treated by a biofilm reactor (the volume load is 3 kg/m)3D, the packing has a bulk density of 96kg/m3Specific surface area of 100m2The amount of the biological film on the filler is 60mg/g, the thickness of the biological film is 48 mu m), the reaction is carried out under the conditions that the saturated dissolved oxygen concentration is 2.5mg/L and the hydraulic retention time is 60h, and then the wastewater reaching the standard is obtained after microfiltration at 25 ℃, 0.1MPa and the surface flow rate of a microfiltration membrane (the aperture is 0.1 mu m) of 2 m/s.
Example 2
(1) Will be 14m3Injecting the desulfurization wastewater 2 of the coal-fired power plant into an adjusting tank for collection, then injecting the wastewater into a wastewater neutralization reaction tank, and adding lime milk to adjust the pH value to 6.9 to obtain neutral wastewater;
(2) injecting the neutral wastewater obtained in the step (1) into a flocculation sedimentation tank, stirring for 20min at 100r/min, adding 14kg of flocculant (prepared by compounding polyaluminium chloride, polyaluminium ferric sulfate, sodium silicate and cationic polyacrylamide in a mass ratio of 40:14:7: 2), stirring for flocculation for 80min at 70r/min, naturally settling for 2.5h, and dehydrating to obtain flocculation wastewater;
(3) the flocculated wastewater obtained in the step (2) is treated by a biofilm reactor (the volume load is 4 kg/m)3D, the packing has a bulk density of 95kg/m3Specific surface area of 140m2The amount of the biological film on the filler is 50mg/g, the thickness of the biological film is 72 mu m), the reaction is carried out under the conditions that the saturated dissolved oxygen concentration is 2.5mg/L and the hydraulic retention time is 72h, and then the wastewater 2 reaching the standard is obtained after microfiltration at 25 ℃, 0.18MPa and the surface flow rate of a microfiltration membrane (the aperture is 0.1 mu m) of 2.8 m/s.
Example 3
(1) Will be 16m3Injecting desulfurization wastewater 3 of a coal-fired power plant into an adjusting tank for collection, then injecting the wastewater into a wastewater neutralization reaction tank, and adding lime milk to adjust the pH value to 7.2 to obtain neutral wastewater;
(2) injecting the neutral wastewater obtained in the step (1) into a flocculation sedimentation tank, stirring for 25min at 80r/min, adding 25kg of flocculant (prepared by compounding polyaluminium chloride, polyaluminium ferric sulfate, sodium silicate and cationic polyacrylamide in a mass ratio of 40:11:6: 3), stirring for flocculation at 50r/min for 70min, naturally settling for 2.5h, and dehydrating to obtain flocculation wastewater;
(3) the flocculated wastewater obtained in the step (2) is processed by a biomembrane reactor (the volume load is 3.5 kg/m)3D, the packing has a bulk density of 98kg/m3A specific surface area of 120m2The amount of the biofilm on the filler is 72mg/g, the thickness of the biofilm is 60 mu m), the reaction is carried out under the conditions that the saturated dissolved oxygen concentration is 2.5mg/L and the hydraulic retention time is 65h, and then the wastewater reaching the standard is obtained after microfiltration at 25 ℃, 0.12MPa and the surface flow rate of a microfiltration membrane (the aperture is 0.08 mu m) of 2.5 m/s.
In order to evaluate the removal efficiency of each pollutant in each step of examples 1 to 3, each pollutant in the wastewater after each treatment was detected. The pH value is detected by a pH glass electrode, suspended matters are detected by a gravimetric method, chloride ions are detected by a potassium chromate indicator titration method, heavy metal ions are detected according to a method in annex A of DL/T997-2020 limestone-Gypsum wet desulphurization wastewater quality control index of coal-fired power plant, COD is detected by a potassium dichromate method, and the result is shown in Table 1.
Table 1 index table of each pollutant in wastewater treated in embodiments 1 to 3 of the present invention
Note: in the table, "-" indicates no calculation.
As can be seen from Table 1, after the treatment by the method, the removal rate of suspended matters in the standard-reaching wastewater is as low as 84mg/L, the removal rate is as high as 99.39%, the removal rate of chloride ions is as low as 361mg/L, the removal rate is as high as 97.71%, the removal rate of heavy metal chromium is as low as 0.2mg/L, the removal rate is as high as 83.33%, the removal rate of COD is as low as 12mg/L, and the removal rate is as high as 93.49%, so that the requirements of DL/T997-2020 limestone-gypsum wet desulphurization wastewater quality control index of coal-fired power plant are met, and the aim of a desulphurization wastewater recycling desulphurization system is fulfilled; wherein, step (1) mainly plays the effect of mediation pH value, is favorable to follow-up flocculation and precipitation, and step (2) mainly plays the effect of getting rid of suspended solids such as colloid, large granule and partial heavy metal ion, and the biomembrane reaction in step (3) mainly plays most heavy metal ion of enrichment to reduce waste water COD's effect, the micro-filtration mainly plays the effect of getting rid of chloridion, micromolecule suspended solid and partial heavy metal colloid.
Claims (5)
1. A treatment method of desulfurization wastewater of a coal-fired power plant is characterized by comprising the following steps:
(1) injecting desulfurization wastewater of a coal-fired power plant into a regulating tank for collection, then injecting the desulfurization wastewater into a wastewater neutralization reaction tank, and adding lime milk to regulate the pH value to obtain neutral wastewater;
(2) injecting the neutral wastewater obtained in the step (1) into a flocculation sedimentation tank, stirring, adding a flocculating agent, stirring again for flocculation, naturally settling, and dehydrating to obtain flocculated wastewater;
(3) and (3) reacting the flocculated wastewater obtained in the step (2) by using a biofilm reactor, and performing membrane treatment to obtain standard wastewater.
2. The method for treating desulfurization wastewater of coal-fired power plants according to claim 1, characterized in that: in the step (1), the pH value of the desulfurization wastewater of the coal-fired power plant is 4.0-6.5, the content of suspended matters is 4500-15000 mg/L, the content of chloride ions is 6000-20000 mg/L, the content of heavy metal ions is 0.2-4.0 mg/L, and the COD is 100-400 mg/L; adding lime milk to adjust the pH value to 6.0-7.8; the mass concentration of the lime milk is 28%.
3. The method for treating desulfurization wastewater of coal-fired power plants according to claim 1 or 2, characterized in that: in the step (2), the dosage of the flocculating agent is 0.05-0.50 times of the mass of the solid suspended matter in the wastewater; the flocculant is prepared by compounding polyaluminium chloride, polyaluminum ferric sulfate, sodium silicate and cationic polyacrylamide according to a mass ratio of 40: 10-15: 5-9: 1-5; before adding the flocculating agent, stirring at the speed of 60-180 r/min for 10-30 min; after the flocculating agent is added, stirring and flocculating at the speed of 30-90 r/min for 30-90 min; the natural settling time is 2.0-2.5 h.
4. The method for treating desulfurization wastewater of a coal-fired power plant according to any one of claims 1 to 3, characterized in that: in the step (3), the saturated dissolved oxygen concentration of the reaction of the biofilm reactor is 0.5-2.5 mg/L, and the hydraulic retention time is 36-90 h; the volume load of the biofilm reactor is 3-5 kg/m3D; the bulk density of the filler in the biofilm reactor is 90-120 kg/m3The specific surface area is 60 to 180m2(ii)/g; the amount of the biological film on the filler is 30-80 mg/g, and the thickness of the biological film is 5-80 μm; the biofilm formation mode of the biofilm reactor adopts the existing sludge discharge and biofilm formation method, and the concentration of activated sludge is 1000-4000 mg/L.
5. The method for treating desulfurization wastewater of a coal-fired power plant according to any one of claims 1 to 4, characterized in that: in the step (3), the membrane treatment is microfiltration; the operating temperature of the microfiltration is 0-45 ℃, the pressure is 0.01-0.20 MPa, and the surface flow rate of the microfiltration membrane is 1-3 m/s; the aperture of the micro-filtration membrane is 0.01-0.10 μm.
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