CN111792772A - Online removal method for organic pollutants in wastewater evaporation crystal slurry - Google Patents
Online removal method for organic pollutants in wastewater evaporation crystal slurry Download PDFInfo
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- 239000002351 wastewater Substances 0.000 title claims abstract description 91
- 239000002002 slurry Substances 0.000 title claims abstract description 67
- 238000000034 method Methods 0.000 title claims abstract description 39
- 238000001704 evaporation Methods 0.000 title claims abstract description 38
- 230000008020 evaporation Effects 0.000 title claims abstract description 38
- 239000013078 crystal Substances 0.000 title claims abstract description 19
- 239000002957 persistent organic pollutant Substances 0.000 title claims abstract description 17
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 66
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 58
- 230000003647 oxidation Effects 0.000 claims abstract description 53
- 238000007872 degassing Methods 0.000 claims abstract description 45
- 239000012452 mother liquor Substances 0.000 claims abstract description 43
- 150000003839 salts Chemical class 0.000 claims abstract description 32
- 238000002425 crystallisation Methods 0.000 claims abstract description 27
- 230000008025 crystallization Effects 0.000 claims abstract description 27
- 238000006243 chemical reaction Methods 0.000 claims abstract description 6
- 230000035484 reaction time Effects 0.000 claims abstract description 3
- 238000006386 neutralization reaction Methods 0.000 claims description 27
- 238000002156 mixing Methods 0.000 claims description 15
- 238000003756 stirring Methods 0.000 claims description 15
- 239000007789 gas Substances 0.000 claims description 14
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 12
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 9
- 239000005416 organic matter Substances 0.000 claims description 9
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 8
- 230000018044 dehydration Effects 0.000 claims description 8
- 238000006297 dehydration reaction Methods 0.000 claims description 8
- 239000007800 oxidant agent Substances 0.000 claims description 8
- 239000001301 oxygen Substances 0.000 claims description 8
- 229910052760 oxygen Inorganic materials 0.000 claims description 8
- 239000007787 solid Substances 0.000 claims description 8
- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 claims description 6
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 claims description 6
- 230000001590 oxidative effect Effects 0.000 claims description 5
- 238000004321 preservation Methods 0.000 claims description 5
- 239000002253 acid Substances 0.000 claims description 3
- 239000003513 alkali Substances 0.000 claims description 3
- 239000000356 contaminant Substances 0.000 claims description 3
- 238000004065 wastewater treatment Methods 0.000 abstract description 2
- 238000005119 centrifugation Methods 0.000 abstract 1
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 18
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 16
- 229910052750 molybdenum Inorganic materials 0.000 description 16
- 239000011733 molybdenum Substances 0.000 description 16
- 229910001220 stainless steel Inorganic materials 0.000 description 16
- 239000010935 stainless steel Substances 0.000 description 16
- 239000000243 solution Substances 0.000 description 13
- 238000011282 treatment Methods 0.000 description 9
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 8
- 239000000463 material Substances 0.000 description 7
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 4
- 239000011780 sodium chloride Substances 0.000 description 4
- 229910052938 sodium sulfate Inorganic materials 0.000 description 4
- 235000011152 sodium sulphate Nutrition 0.000 description 4
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 3
- 229910052719 titanium Inorganic materials 0.000 description 3
- 239000010936 titanium Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 238000012856 packing Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000002918 waste heat Substances 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 230000033558 biomineral tissue development Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000011112 process operation Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
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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
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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
- 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
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/06—Flash 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
- C02F1/20—Treatment of water, waste water, or sewage by degassing, i.e. liberation of dissolved gases
-
- 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
- C02F1/38—Treatment of water, waste water, or sewage by centrifugal separation
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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
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
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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
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/722—Oxidation by peroxides
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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
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic 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
- C02F2201/00—Apparatus for treatment of water, waste water or sewage
- C02F2201/002—Construction details of the apparatus
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- Life Sciences & Earth Sciences (AREA)
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- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
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- Heat Treatment Of Water, Waste Water Or Sewage (AREA)
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Abstract
The invention discloses an online removal method of organic pollutants in wastewater evaporation crystal slurry, and belongs to the field of wastewater treatment. The method comprises the following steps: the pretreated wastewater is sequentially concentrated by a feeding tank, a preheater, a first degassing tower, a heater and an evaporator, concentrated solution enters a crystallizer after passing through a forced circulation heater, salt slurry is sent to a separator, crystallized salt and mother liquor are generated after centrifugation, the slurry in the crystallizer is mixed with the mother liquor to form recycled slurry, one part of the recycled slurry returns to the forced circulation heater, the other part of the recycled slurry is mixed with water discharged from the feeding tank and enters an oxidation tank, and the water discharged from the oxidation tank returns to the forced circulation heater after pH value adjustment and degassing. The volume ratio of the effluent of the feeding tank in the oxidation tank to the recycled slurry is 1: 0.5-1: 10, the reaction temperature is 50-100 ℃, and the reaction time is 60-300 min. The invention can reduce the concentration of organic matters in the slurry on line, ensure the smooth operation of the crystallization process and improve the quality of condensed water and crystallized salt.
Description
Technical Field
The invention relates to a method for treating evaporated crystal slurry by using waste water, belongs to the technical field of high-salt and high-organic-pollutant waste water treatment, and particularly relates to a method for treating evaporated crystal slurry by using an advanced oxidation technology.
Background
In recent years, with the advancement of national ecological civilization construction in the depth direction, a waste water zero emission treatment technology becomes a research hotspot. The waste water 'zero discharge' treatment process generally comprises pretreatment, concentration and decrement and evaporative crystallization. The pretreatment is generally to remove hardness, oil, turbidity, organic matters and the like, and the normal operation of the subsequent process is ensured. The concentration and decrement generally includes membrane method concentration and decrement and thermal method concentration and decrement, and when the amount of wastewater is large, the concentration and decrement is often performed by adopting a membrane method. The evaporative crystallization process commonly used comprises normal-pressure low-temperature evaporative crystallization, multiple-effect evaporative crystallization, mechanical vapor recompression evaporative crystallization, bypass flue evaporative crystallization, direct flue evaporative crystallization and the like. The flue evaporation process has the advantage of low treatment cost, but the treatment water amount is relatively small, and the flue evaporation process is generally applied to industries with available waste heat due to the fact that enterprises have enough available waste heat. The processes of multi-effect evaporation, mechanical vapor recompression evaporation crystallization and the like are not limited by the amount of waste water, can be coupled with a recycling process of salt, and are widely applied to the industries of thermal power, coal chemical industry, paper making and the like.
Because the organic matter can not crystallize in the crystallizer basically, the more the organic matter is accumulated, the evaporation efficiency is influenced, even the wastewater becomes viscous, the crystallization of dissolved salts is disturbed, the service life of an evaporator is possibly influenced, and meanwhile, the organic matter carried in the crystallized salt influences the quality of the crystallized salt. Therefore, it is necessary to reduce the organic matters in the evaporative crystallization system, and ensure the smooth proceeding of the evaporative crystallization process and the quality of the crystallized salt.
The prior treatment modes of organic matters in the wastewater subjected to evaporative crystallization comprise pretreatment before an evaporative crystallization system, treatment in the evaporative crystallization process, a mother liquor discharge method and the like.
The pretreatment before the evaporation crystallization can reduce the content of organic matters entering an evaporation crystallization system, but in the evaporation process, the waste water can be concentrated, and the organic matters in the waste water can still be increased to a certain concentration, thereby influencing the evaporation and crystallization system. The main problem of removing organic matters in the evaporation concentration process is that the added catalyst or oxidant and the decomposition products thereof enter into the crystallized salt, and the quality of the crystallized salt is influenced. Gases produced by the mineralization of organic contaminants during oxidation can also adversely affect the evaporator and vapor compressor. The discharged crystallization mother liquor reduces the amount of organic pollutants in the crystallizer to a certain extent by discharging part of high-concentration organic matters out of the system, but the problem that the high-concentration organic matters in the crystallizer influence the crystallization process and the quality of crystallized salt is not fundamentally solved depending on the discharge amount of the mother liquor. Meanwhile, the discharge of a large amount of mother liquor reduces the yield of the crystallized salt. The discharged mother liquor is generally used for removing a small amount of impurity ions which are difficult to crystallize in the wastewater.
Disclosure of Invention
Aiming at the influence of organic pollutants on the evaporation crystallization process and the quality of product salt, the invention provides an online removal method of the organic pollutants in the wastewater evaporation crystallization slurry, the concentration of the organic pollutants in the evaporation crystallizer can be controlled in a proper range after treatment, the purity of the product salt is ensured, and the treatment process does not influence the crystallization process.
The technical scheme adopted by the invention for solving the problems is as follows: an online removal method for organic pollutants in wastewater evaporation crystal slurry is characterized by comprising the following steps:
(1) the pretreated wastewater enters a feeding tank, and the effluent of the feeding tank enters a first degassing tower after being preheated by a preheater to remove non-condensable gas;
(2) the water discharged from the first degassing tower enters a heater, and the wastewater enters an evaporator after being heated;
(3) one part of the water discharged from the evaporator returns to the heater for circulating heating and evaporation, and the other part enters the forced circulation heater;
(4) the effluent of the forced circulation heater enters a crystallizer, when slurry reaches a certain concentration, a part of salt slurry is sent to a separator, solids in the underflow of the separator are sent to a centrifuge for dehydration to generate crystallized salt, and the centrifugate and the slurry overflowing from the separator enter a mother liquor tank; the other part of the slurry returns to the forced circulation heater through a forced circulation pipeline;
(5) one part of the mother liquor in the mother liquor tank enters a forced circulation pipeline, and the other part of the mother liquor is discharged out of the system;
(6) mixing the effluent of the feed tank with part of the recirculated slurry in the forced circulation pipeline in an oxidation tank, adding acid liquor to adjust the pH value, and then adding an oxidant to carry out oxidation;
(7) the effluent of the oxidation tank enters a neutralization tank, alkali liquor is added to adjust the pH value of the wastewater, and the effluent of the neutralization tank enters a second degassing tower;
(8) the effluent of the second degassing tower returns to the forced circulation heater;
(9) the heat sources used by the heater and the forced circulation heater are raw steam or steam recycled by a steam compressor;
(10) condensed water generated after the steam of the heater and the forced circulation heater is condensed is discharged to a condensed water tank;
(11) the condensed water in the condensed water tank exchanges heat with the wastewater in the preheater to heat the wastewater.
Furthermore, the pretreatment of the wastewater refers to one or more of the treatments of turbidity removal, hardness removal, oil removal and the like.
Further, the feed tank mainly carries out quality of water yield equilibrium, ensures steady feed liquor.
Further, the preheater is used for heating the waste water to meet the water inlet requirement of the degassing tower.
Furthermore, when the wastewater in the first degassing tower passes through the packing layer, the falling wastewater is contacted with the convection gas, and the non-condensable gas in the wastewater is removed. And collecting the wastewater at the bottom of the first degassing tower, and then entering an evaporative crystallization system.
Further, the evaporator heats the waste water by using steam, the heated waste water is evaporated in the evaporation tank for concentration, the concentrated solution enters the forced circulation heater for reheating and then enters the crystallizer for flash evaporation, and crystals are precipitated in the crystallizer. The steam in the heater and the forced circulation heater is condensed after releasing latent heat and then enters the condensate water tank.
Further, the slurry in the crystallizer and the mother liquor in the mother liquor tank are mixed in a forced circulation pipeline to form recycled slurry, the recycled slurry is divided into two parts, one part is mixed with the water discharged from the evaporator and then enters a forced circulation heater, and the other part enters the oxidation tank.
Furthermore, oxidation reaction mainly occurs in the oxidation tank to degrade organic pollutants. Because the temperature of the recycled slurry is high, in order to maintain proper reaction temperature, the temperature is adjusted by adopting a mode of mixing the effluent of the feeding tank and the recycled slurry, the volume ratio of the effluent of the feeding tank to the recycled slurry is 1: 0.5-1: 10, and the reaction temperature is controlled at 50-100 ℃. In order to maintain the reaction temperature, the oxidation tank needs to be kept warm. The oxidizing agent may be H, depending on the nature of the crystalline salt2O2Or sodium persulfate is added into the oxidation tank, hydrochloric acid or sulfuric acid is added into the oxidation tank to adjust the pH value of the mixed solution, the oxidation reaction pH value is kept at 3-6, the reaction time is 60-300 min, and the addition amount of the oxidant is 1.2-3 times of the theoretical oxygen demand of the completely oxidized organic matter to be removed. The oxidation tank is made of high molybdenum stainless steel, titanium material and the like, and is provided with a stirring device.
And further, feeding effluent of the oxidation tank into a neutralization tank, adding sodium hydroxide into the neutralization tank, and adjusting the pH value of the wastewater to 6-8. The material of neutralization jar is high molybdenum stainless steel, titanium material etc. is equipped with agitating unit, and the external layer of jar keeps warm.
Further, the second degassing tower is mainly used for removing gas, micromolecule low-boiling point substances and the like generated in the oxidation reaction process, when the wastewater passes through the packing layer, the falling wastewater is contacted with convection gas, non-condensable gas in the wastewater is removed, and the wastewater is collected at the bottom of the second degassing tower and then returns to the forced circulation heater. The second tower body of the degassing tower is made of high molybdenum stainless steel, titanium materials and the like.
Compared with the prior art, the invention has the following advantages and effects: the invention can efficiently and quickly reduce the concentration of organic pollutants in the slurry, reduce the influence of organic matters on the evaporation crystallization process, and can select different oxidants according to the properties of the crystallized salt, thereby obviously improving the quality of the crystallized salt. The invention has stable process operation, simple and convenient management and obvious effect.
Drawings
FIG. 1 is a process flow diagram in an embodiment of the invention.
Detailed Description
The present invention will be described in further detail below by way of examples with reference to the accompanying drawings, which are illustrative of the present invention and are not to be construed as limiting the present invention.
Example 1.
The COD of high-salinity wastewater is about 1000-1500 mg/L, the pH value is 7.2-7.5, the NaCl content is about 5-6%, the temperature is about 15-20 ℃, the wastewater after the pretreatment of turbidity removal and hardness removal is introduced into a feeding tank, the effluent of the feeding tank enters a first degassing tower after being preheated by a preheater, and non-condensable gas is removed. And the water discharged from the first degassing tower enters a heater, the wastewater is heated and then enters an evaporator for evaporation, the wastewater is concentrated, the water discharged from the evaporator enters a forced circulation heater, and the water discharged from the forced circulation heater enters a crystallizer for flash evaporation. When the concentration of crystal slurry precipitated in the crystallizer reaches 25-29%, a part of salt slurry is sent to a separator, solids in the underflow of the separator are sent to a pusher centrifuge for dehydration to generate crystallized salt, and the centrifugate and the concentrated solution overflowed from the separator enter a mother liquor tank; and the other part of the slurry enters a forced circulation pipeline for recirculation. One part of the mother liquor in the mother liquor tank enters a forced circulation pipeline, and the other part of the mother liquor is discharged out of the system. Mixing the effluent of the feeding tank and the recycled slurry in the forced circulation pipeline in a volume ratio of 1: 0.5-1: 0.6 in an oxidation tank, adding hydrochloric acid into the oxidation tank at the temperature of about 50 ℃ after mixing, adjusting the pH value to 3-4, and then adding H2O2Carrying out an oxidation reaction for a reaction time300min，H2O2The addition amount is 1.2 times of the theoretical oxygen demand of the complete oxidation of the organic matter to be removed, the material of the oxidation tank is 6 percent of molybdenum stainless steel, the stirring device is arranged, and the heat-insulating layer is arranged outside the oxidation tank. And (3) enabling effluent of the oxidation tank to enter a neutralization tank, adding NaOH solution into the neutralization tank, adjusting the pH value of the wastewater to be 7-8, wherein the neutralization tank is made of 6% molybdenum stainless steel and is provided with a stirring device, preserving heat on the outer layer of the tank body, enabling the neutralized wastewater to enter a second degassing tower, and the second degassing tower is made of 6% molybdenum stainless steel. And the effluent of the second degassing tower enters a forced circulation heater. The heat source of the heater and the forced circulation heater is steam, the steam enters the shell side of the evaporator, is condensed on the outer side of the pipe wall after heating the waste water, and then is discharged to the condensed water tank. The condensed water exchanges heat with the water discharged from the feeding tank and is recycled.
Example 2.
The COD of high-salinity wastewater is about 2200-2500 mg/L, the pH value is 7.0-7.6, the NaCl content is about 10-11%, the temperature is about 10-25 ℃, the wastewater after the pretreatment of turbidity removal and hardness removal is introduced into a feeding tank, the effluent of the feeding tank enters a first degassing tower after being preheated by a preheater, and non-condensable gas is removed. And the water discharged from the first degassing tower enters a heater, the wastewater is heated and then enters an evaporator for evaporation, the wastewater is concentrated, the water discharged from the evaporator enters a forced circulation heater, and the water discharged from the forced circulation heater enters a crystallizer for flash evaporation. When the concentration of crystal slurry precipitated in the crystallizer reaches 25-29%, a part of salt slurry is sent to a separator, solids in the underflow of the separator are sent to a pusher centrifuge for dehydration to generate crystallized salt, and the centrifugate and the concentrated solution overflowed from the separator enter a mother liquor tank; and the other part of the slurry enters a forced circulation pipeline for recirculation. One part of the mother liquor in the mother liquor tank enters a forced circulation pipeline, and the other part of the mother liquor is discharged out of the system. Mixing the effluent of the feeding tank and the recycled slurry in the forced circulation pipeline in a volume ratio of 1: 1.2-1: 1.7 in an oxidation tank, adding hydrochloric acid into the oxidation tank at the temperature of about 75 ℃ after mixing, adjusting the pH value to 3-4, and then adding H2O2Carrying out oxidation reaction for 100min, H2O2The addition amount is 1.5 times of the theoretical oxygen demand of the complete oxidation of the organic matter to be removed, the material of the oxidation tank is 6 percent of molybdenum stainless steel, the stirring device is arranged, and the heat-insulating layer is arranged outside the oxidation tank. The effluent of the oxidation tank entersAnd (2) feeding the wastewater into a neutralization tank, adding NaOH solution into the neutralization tank, adjusting the pH value of the wastewater to 6.5-7.5, wherein the neutralization tank is made of 6% molybdenum stainless steel, a stirring device is arranged, the outer layer of the tank body is subjected to heat preservation, the neutralized wastewater enters a second degassing tower, and the second degassing tower is made of 6% molybdenum stainless steel. And the effluent of the second degassing tower enters a forced circulation heater. The heat source of the heater and the forced circulation heater is steam, the steam enters the shell side of the evaporator, is condensed on the outer side of the pipe wall after heating the waste water, and then is discharged to the condensed water tank. The condensed water exchanges heat with the water discharged from the feeding tank and is recycled.
Example 3.
The COD of high-salt wastewater is 6000-6500 mg/L, the pH value is 6.0-7.0, the concentration of sodium sulfate is 10-12%, the temperature is about 10-25 ℃, wastewater subjected to turbidity removal and hardness removal pretreatment is introduced into a feeding tank, effluent of the feeding tank is preheated by a preheater and then enters a first degassing tower, and non-condensable gas is removed. And the water discharged from the first degassing tower enters a heater, the wastewater is heated and then enters an evaporator for evaporation, the wastewater is concentrated, the water discharged from the evaporator enters a forced circulation heater, and the water discharged from the forced circulation heater enters a crystallizer for flash evaporation. When the concentration of crystal slurry precipitated in the crystallizer reaches 25-29%, a part of salt slurry is sent to a separator, solids in the underflow of the separator are sent to a pusher centrifuge for dehydration to generate crystallized salt, and the centrifugate and the concentrated solution overflowed from the separator enter a mother liquor tank; and the other part of the slurry enters a forced circulation pipeline for recirculation. One part of the mother liquor in the mother liquor tank enters a forced circulation pipeline, and the other part of the mother liquor is discharged out of the system. Mixing the effluent of the feeding tank and the recycled slurry in the forced circulation pipeline in a volume ratio of 1: 7-1: 9 in an oxidation tank, wherein the temperature after mixing is about 100 ℃, adding a sulfuric acid solution into the oxidation tank, adjusting the pH value to be 5-6, then adding sodium persulfate to perform oxidation reaction for 60min, wherein the adding amount of the sodium persulfate is 3 times of the theoretical oxygen demand of complete oxidation of organic matters to be removed, the oxidation tank is made of TA16, a stirring device is arranged, and a heat insulation layer is arranged outside the oxidation tank. And (3) enabling effluent of the oxidation tank to enter a neutralization tank, adding NaOH into the neutralization tank, adjusting the pH value of the wastewater to be 6-6.5, wherein the neutralization tank is made of TA12 and is provided with a stirring device, the outer layer of the tank body is subjected to heat preservation, the neutralized wastewater enters a second degassing tower, and the second degassing tower is made of TA 12. And the effluent of the second degassing tower enters a forced circulation heater. The heat source of the heater and the forced circulation heater is steam, the steam enters the shell side of the evaporator, is condensed on the outer side of the pipe wall after heating the waste water, and then is discharged to the condensed water tank. The condensed water exchanges heat with the water discharged from the feeding tank and is recycled.
Example 4.
The COD of high-salinity wastewater is 3000-400 mg/L, the pH value is 7.0-7.8, the concentration of sodium sulfate is 6-7%, the temperature is about 10-20 ℃, the wastewater subjected to turbidity removal and hardness removal pretreatment is introduced into a feeding tank, the effluent of the feeding tank is preheated by a preheater and then enters a first degassing tower, and non-condensable gas is removed. And the water discharged from the first degassing tower enters a heater, the wastewater is heated and then enters an evaporator for evaporation, the wastewater is concentrated, the water discharged from the evaporator enters a forced circulation heater, and the water discharged from the forced circulation heater enters a crystallizer for flash evaporation. When the concentration of crystal slurry precipitated in the crystallizer reaches 25-29%, a part of salt slurry is sent to a separator, solids in the underflow of the separator are sent to a pusher centrifuge for dehydration to generate crystallized salt, and the centrifugate and the concentrated solution overflowed from the separator enter a mother liquor tank; and the other part of the slurry enters a forced circulation pipeline for recirculation. One part of the mother liquor in the mother liquor tank enters a forced circulation pipeline, and the other part of the mother liquor is discharged out of the system. Mixing the effluent of the feeding tank and the recycled slurry in the forced circulation pipeline in a volume ratio of 1: 3-1: 4 in an oxidation tank, wherein the temperature after mixing is about 90 ℃, adding a sulfuric acid solution into the oxidation tank, adjusting the pH value to 3-4, and then adding H2O2Carrying out oxidation reaction for 180min, H2O2The addition amount is 1.8 times of the theoretical oxygen demand of the complete oxidation of the organic matter to be removed, the material of the oxidation tank is 6 percent of molybdenum stainless steel, the stirring device is arranged, and the heat-insulating layer is arranged outside the oxidation tank. And (3) introducing the effluent of the oxidation tank into a neutralization tank, adding sulfuric acid into the neutralization tank, adjusting the pH value of the wastewater to 6-7, wherein the neutralization tank is made of TA12 and is provided with a stirring device, the outer layer of the tank body is subjected to heat preservation, and the neutralized wastewater enters a second degassing tower which is made of TA 12. And the effluent of the second degassing tower enters a forced circulation heater. The heat source of the heater and the forced circulation heater is steam, the steam enters the shell side of the evaporator, is condensed on the outer side of the pipe wall after heating the waste water, and then is discharged to the condensed water tank. The condensed water exchanges heat with the water discharged from the feeding tank and is recycled.
Example 5.
The COD of high-salt wastewater is 3500-4000 mg/L, the pH value is 7.0-7.5, the concentration of sodium sulfate is 8-10%, the concentration of sodium chloride is 2-3%, and the temperature is about 5-15 ℃, the wastewater subjected to turbidity removal and hardness removal pretreatment is introduced into a feeding tank, the effluent of the feeding tank is preheated by a preheater and then enters a first degassing tower, and non-condensable gas is removed. And the water discharged from the first degassing tower enters a heater, the wastewater is heated and then enters an evaporator for evaporation, the wastewater is concentrated, the water discharged from the evaporator enters a forced circulation heater, and the water discharged from the forced circulation heater enters a crystallizer for flash evaporation. When the concentration of crystal slurry precipitated in the crystallizer reaches 25-29%, a part of salt slurry is sent to a separator, solids in the underflow of the separator are sent to a pusher centrifuge for dehydration to generate crystallized salt, and the centrifugate and the concentrated solution overflowed from the separator enter a mother liquor tank; and the other part of the slurry enters a forced circulation pipeline for recirculation. One part of the mother liquor in the mother liquor tank enters a forced circulation pipeline, and the other part of the mother liquor is discharged out of the system. Mixing the effluent of the feeding tank and the recycled slurry in the forced circulation pipeline in a volume ratio of 1: 2-1: 3 in an oxidation tank, wherein the temperature after mixing is about 80 ℃, adding a sulfuric acid solution into the oxidation tank, adjusting the pH value to be 4-5, then adding sodium persulfate to perform oxidation reaction for 120min, wherein the addition amount of the sodium persulfate is 2 times of the theoretical oxygen demand of complete oxidation of organic matters to be removed, the oxidation tank is made of 6% molybdenum stainless steel, a stirring device is arranged, and a heat insulation layer is arranged outside the oxidation tank. And (3) enabling effluent of the oxidation tank to enter a neutralization tank, adding NaOH into the neutralization tank, adjusting the pH value of the wastewater to 6-6.5, wherein the neutralization tank is made of 6% molybdenum stainless steel, a stirring device is arranged, the outer layer of the tank body is subjected to heat preservation, the neutralized wastewater enters a second degassing tower, and the second degassing tower is made of 6% molybdenum stainless steel. And the effluent of the second degassing tower enters a forced circulation heater. The heat source of the heater and the forced circulation heater is steam, the steam enters the shell side of the evaporator, is condensed on the outer side of the pipe wall after heating the waste water, and then is discharged to the condensed water tank. The condensed water exchanges heat with the water discharged from the feeding tank and is recycled.
Example 6.
The COD of the high-salt wastewater is 2000-3000 mg/L, the pH value is 7.0-7.8, the concentration of sodium sulfate is 0.2-0.5%, the concentration of sodium chloride is 8-10%, the temperature is about 10-20 ℃,introducing the wastewater subjected to turbidity and hardness removal pretreatment into a feeding tank, preheating the effluent of the feeding tank by a preheater, and then entering a first degassing tower to remove non-condensable gas. And the water discharged from the first degassing tower enters a heater, the wastewater is heated and then enters an evaporator for evaporation, the wastewater is concentrated, the water discharged from the evaporator enters a forced circulation heater, and the water discharged from the forced circulation heater enters a crystallizer for flash evaporation. When the concentration of crystal slurry precipitated in the crystallizer reaches 25-29%, a part of salt slurry is sent to a separator, solids in the underflow of the separator are sent to a pusher centrifuge for dehydration to generate crystallized salt, and the centrifugate and the concentrated solution overflowed from the separator enter a mother liquor tank; and the other part of the slurry enters a forced circulation pipeline for recirculation. One part of the mother liquor in the mother liquor tank is sent into a forced circulation pipeline, and the other part of the mother liquor is discharged out of the system. Mixing the effluent of the feeding tank and the recycled slurry in the forced circulation pipeline in a volume ratio of 1: 3-1: 4 in an oxidation tank, wherein the temperature after mixing is about 90 ℃, adding hydrochloric acid into the oxidation reaction tank, adjusting the pH value to 3-4, and then adding H2O2Carrying out oxidation reaction for 240min, H2O2The addition amount is 1.8 times of the theoretical oxygen demand of the complete oxidation of the organic matter to be removed, the oxidation reaction tank is made of 6% molybdenum stainless steel, a stirring device is arranged, and a heat-insulating layer is arranged outside the oxidation reaction tank. And (3) enabling effluent of the oxidation reaction tank to enter a neutralization tank, adding NaOH solution into the neutralization tank, adjusting the pH value of the wastewater to be 6-7, wherein the neutralization tank is made of 6% molybdenum stainless steel and is provided with a stirring device, preserving heat on the outer layer of the tank body, enabling the neutralized wastewater to enter a second degassing tower, and the second degassing tower is made of 6% molybdenum stainless steel. And the effluent of the second degassing tower enters a forced circulation heater. The heat source of the heater and the forced circulation heater is steam, the steam enters the shell side of the evaporator, is condensed on the outer side of the pipe wall after heating the waste water, and then is discharged to the condensed water tank. The condensed water exchanges heat with the water discharged from the feeding tank and is recycled.
Those not described in detail in this specification are well within the skill of the art.
Although the present invention has been described with reference to the above embodiments, it should be understood that the scope of the present invention is not limited thereto, and that various changes and modifications can be made by those skilled in the art without departing from the spirit and scope of the present invention.
Claims (8)
1. An online removal method for organic pollutants in wastewater evaporation crystal slurry is characterized by comprising the following steps:
(1) the pretreated wastewater enters a feeding tank, and the effluent of the feeding tank enters a first degassing tower after being preheated by a preheater to remove non-condensable gas;
(2) the water discharged from the first degassing tower enters a heater, and the wastewater enters an evaporator after being heated;
(3) one part of the water discharged from the evaporator returns to the heater for circulating heating and evaporation, and the other part enters the forced circulation heater;
(4) the effluent of the forced circulation heater enters a crystallizer, when slurry reaches a certain concentration, a part of salt slurry is sent to a separator, solids in the underflow of the separator are sent to a centrifuge for dehydration to generate crystallized salt, and the centrifugate and the slurry overflowing from the separator enter a mother liquor tank; the other part of the slurry returns to the forced circulation heater through a forced circulation pipeline;
(5) one part of the mother liquor in the mother liquor tank enters a forced circulation pipeline, and the other part of the mother liquor is discharged out of the system;
(6) mixing the effluent of the feed tank with part of the recirculated slurry in the forced circulation pipeline in an oxidation tank, adding acid liquor to adjust the pH value, and then adding an oxidant to carry out oxidation;
(7) the effluent of the oxidation tank enters a neutralization tank, alkali liquor is added to adjust the pH value of the wastewater, and the effluent of the neutralization tank enters a second degassing tower;
(8) the effluent of the second degassing tower returns to the forced circulation heater;
(9) the heat sources used by the heater and the forced circulation heater are raw steam or steam recycled by a steam compressor;
(10) condensed water generated after the steam of the heater and the forced circulation heater is condensed is discharged to a condensed water tank;
(11) the condensed water in the condensed water tank exchanges heat with the wastewater in the preheater to heat the wastewater.
2. The method for removing organic pollutants in waste water evaporation crystal slurry in accordance with claim 1, wherein in steps (4) and (5), slurry in a crystallizer and mother liquor in a mother liquor tank are mixed in a forced circulation pipeline to form recycled slurry, the recycled slurry is divided into two parts, one part is mixed with water discharged from an evaporator and then enters a forced circulation heater, and the other part enters an oxidation tank.
3. The method for removing organic pollutants in waste water evaporation crystal slurry in online manner according to claim 1, wherein in the step (6), the volume ratio of the outlet water of the feeding tank entering the oxidation tank to the recycled slurry is 1: 0.5-1: 10, and the reaction temperature is 50-100 ℃.
4. The method for removing organic pollutants in waste water evaporation crystal slurry in online manner as claimed in claim 1, wherein in the step (6), the oxidation tank is provided with a stirring device, and the outer layer of the tank body is subjected to heat preservation.
5. The method for online removal of organic pollutants from wastewater evaporative crystallization slurry as claimed in claim 1, wherein in step (6), the added acid solution is hydrochloric acid or sulfuric acid, and the pH value is adjusted to 3-6.
6. The method for on-line removal of organic contaminants from a slurry of wastewater evaporative crystals as claimed in claim 1, wherein in step (6), the oxidizing agent is H2O2Or sodium persulfate, the reaction time is 60-300 min, and the addition amount of the oxidant is 1.2-3 times of the theoretical oxygen demand of the completely oxidized organic matter to be removed.
7. The method for on-line removal of organic contaminants from a slurry of evaporated crystals of wastewater according to claim 1, wherein in step (7), the neutralization tank is provided with a stirring device, and the outer layer of the tank is kept warm.
8. The method for online removal of organic pollutants in wastewater evaporative crystallization slurry according to claim 1, wherein in the step (7), alkali liquor is added into the neutralization tank, and the pH value of the wastewater is adjusted to 6-8.
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