CN114409187A - Caprolactam production wastewater treatment process - Google Patents
Caprolactam production wastewater treatment process Download PDFInfo
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- CN114409187A CN114409187A CN202210047101.9A CN202210047101A CN114409187A CN 114409187 A CN114409187 A CN 114409187A CN 202210047101 A CN202210047101 A CN 202210047101A CN 114409187 A CN114409187 A CN 114409187A
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- caprolactam
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- oxidation treatment
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- JBKVHLHDHHXQEQ-UHFFFAOYSA-N epsilon-caprolactam Chemical compound O=C1CCCCCN1 JBKVHLHDHHXQEQ-UHFFFAOYSA-N 0.000 title claims abstract description 170
- 238000000034 method Methods 0.000 title claims abstract description 70
- 230000008569 process Effects 0.000 title claims abstract description 39
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 34
- 238000004065 wastewater treatment Methods 0.000 title claims abstract description 9
- 230000003647 oxidation Effects 0.000 claims abstract description 123
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 123
- 239000002351 wastewater Substances 0.000 claims abstract description 97
- 239000007788 liquid Substances 0.000 claims abstract description 87
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 claims abstract description 34
- 229910052921 ammonium sulfate Inorganic materials 0.000 claims abstract description 32
- 235000011130 ammonium sulphate Nutrition 0.000 claims abstract description 32
- 239000007800 oxidant agent Substances 0.000 claims abstract description 31
- 230000001590 oxidative effect Effects 0.000 claims abstract description 29
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 25
- 229910001868 water Inorganic materials 0.000 claims abstract description 25
- 239000012466 permeate Substances 0.000 claims abstract description 19
- 238000001704 evaporation Methods 0.000 claims abstract description 17
- 230000008020 evaporation Effects 0.000 claims abstract description 17
- 239000013078 crystal Substances 0.000 claims abstract description 16
- 238000001223 reverse osmosis Methods 0.000 claims abstract description 14
- 238000002425 crystallisation Methods 0.000 claims abstract description 12
- 230000008025 crystallization Effects 0.000 claims abstract description 12
- 239000003054 catalyst Substances 0.000 claims abstract description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical group [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 22
- 239000001301 oxygen Substances 0.000 claims description 22
- 229910052760 oxygen Inorganic materials 0.000 claims description 22
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 claims description 21
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 16
- 238000005507 spraying Methods 0.000 claims description 13
- 238000001179 sorption measurement Methods 0.000 claims description 12
- 238000000605 extraction Methods 0.000 claims description 11
- 238000010992 reflux Methods 0.000 claims description 8
- 239000003795 chemical substances by application Substances 0.000 claims description 5
- 230000003472 neutralizing effect Effects 0.000 claims description 4
- 125000004122 cyclic group Chemical group 0.000 claims description 2
- 230000001105 regulatory effect Effects 0.000 claims 1
- 238000011084 recovery Methods 0.000 abstract description 7
- 239000002253 acid Substances 0.000 abstract description 4
- 229910017053 inorganic salt Inorganic materials 0.000 abstract description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 14
- 238000006243 chemical reaction Methods 0.000 description 9
- 239000012528 membrane Substances 0.000 description 9
- 238000004821 distillation Methods 0.000 description 8
- 239000005416 organic matter Substances 0.000 description 8
- 239000011347 resin Substances 0.000 description 8
- 229920005989 resin Polymers 0.000 description 8
- 150000003839 salts Chemical class 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 6
- 230000002378 acidificating effect Effects 0.000 description 5
- 238000006731 degradation reaction Methods 0.000 description 5
- 239000012535 impurity Substances 0.000 description 5
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 239000005708 Sodium hypochlorite Substances 0.000 description 4
- 235000011114 ammonium hydroxide Nutrition 0.000 description 4
- 230000015556 catabolic process Effects 0.000 description 4
- 230000003197 catalytic effect Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 239000007791 liquid phase Substances 0.000 description 4
- 230000008707 rearrangement Effects 0.000 description 4
- 229920006395 saturated elastomer Polymers 0.000 description 4
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 4
- -1 cyclohexylamine peroxide Chemical class 0.000 description 3
- 238000005265 energy consumption Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000010410 layer Substances 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- BZSXEZOLBIJVQK-UHFFFAOYSA-N 2-methylsulfonylbenzoic acid Chemical compound CS(=O)(=O)C1=CC=CC=C1C(O)=O BZSXEZOLBIJVQK-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 2
- 239000003463 adsorbent Substances 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- VEZUQRBDRNJBJY-UHFFFAOYSA-N cyclohexanone oxime Chemical compound ON=C1CCCCC1 VEZUQRBDRNJBJY-UHFFFAOYSA-N 0.000 description 2
- 238000003795 desorption Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000945 filler Substances 0.000 description 2
- 230000004907 flux Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 244000005700 microbiome Species 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 239000010865 sewage Substances 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 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 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- PAFZNILMFXTMIY-UHFFFAOYSA-N Cyclohexylamine Natural products NC1CCCCC1 PAFZNILMFXTMIY-UHFFFAOYSA-N 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 229920002292 Nylon 6 Polymers 0.000 description 1
- KHPLPBHMTCTCHA-UHFFFAOYSA-N ammonium chlorate Chemical compound N.OCl(=O)=O KHPLPBHMTCTCHA-UHFFFAOYSA-N 0.000 description 1
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium peroxydisulfate Substances [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 description 1
- VAZSKTXWXKYQJF-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)OOS([O-])=O VAZSKTXWXKYQJF-UHFFFAOYSA-N 0.000 description 1
- 229910001870 ammonium persulfate Inorganic materials 0.000 description 1
- WTFDXZSHRKYAOB-UHFFFAOYSA-N anthracene-9,10-dione;toluene Chemical compound CC1=CC=CC=C1.C1=CC=C2C(=O)C3=CC=CC=C3C(=O)C2=C1 WTFDXZSHRKYAOB-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000011143 downstream manufacturing Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 239000000543 intermediate Substances 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000012044 organic layer Substances 0.000 description 1
- 238000006864 oxidative decomposition reaction Methods 0.000 description 1
- 238000006146 oximation reaction Methods 0.000 description 1
- VLTRZXGMWDSKGL-UHFFFAOYSA-M perchlorate Inorganic materials [O-]Cl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-M 0.000 description 1
- VLTRZXGMWDSKGL-UHFFFAOYSA-N perchloric acid Chemical compound OCl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-N 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- BAZAXWOYCMUHIX-UHFFFAOYSA-M sodium perchlorate Chemical compound [Na+].[O-]Cl(=O)(=O)=O BAZAXWOYCMUHIX-UHFFFAOYSA-M 0.000 description 1
- 229910001488 sodium perchlorate Inorganic materials 0.000 description 1
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
Classifications
-
- 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
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C1/00—Ammonia; Compounds thereof
- C01C1/24—Sulfates of ammonium
- C01C1/242—Preparation from ammonia and sulfuric acid or sulfur trioxide
-
- 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
-
- 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
- C02F1/26—Treatment of water, waste water, or sewage by extraction
-
- 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
- C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by 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
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/725—Treatment of water, waste water, or sewage by oxidation by catalytic oxidation
-
- 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
- C02F1/727—Treatment of water, waste water, or sewage by oxidation using pure oxygen or oxygen rich gas
-
- 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
- C02F1/74—Treatment of water, waste water, or sewage by oxidation with air
-
- 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
- C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
- C02F2103/36—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32 from the manufacture of organic compounds
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Inorganic Chemistry (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Treatment Of Water By Oxidation Or Reduction (AREA)
Abstract
The invention provides a caprolactam production wastewater treatment process, which comprises the following steps: introducing caprolactam wastewater and an oxidant into an oxidation treatment unit filled with a catalyst together, and adjusting the temperature and pressure of the oxidation treatment unit to enable the caprolactam wastewater and the oxidant to react under the subcritical water condition to obtain oxidation treatment liquid; introducing the oxidation treatment liquid into a concentration treatment unit, and obtaining a concentrated liquid and a permeate liquid by adopting a reverse osmosis method; introducing the concentrated solution into an evaporation treatment unit, obtaining ammonium sulfate crystals, residual liquid and condensate through evaporation and crystallization, and recovering the ammonium sulfate crystals; and introducing the permeate, the residual liquid and the condensate into a biochemical treatment unit for biochemical treatment. The invention treats the wastewater by the subcritical water oxidation method, so that the biodegradability of the wastewater is improved, and the subsequent inorganic salt recovery and biochemical treatment are facilitated; and a strong oxidant and acid are not needed in the subcritical water oxidation process, so that the cost is low and the equipment loss is small.
Description
Technical Field
The invention relates to the technical field of industrial wastewater treatment, in particular to a caprolactam production wastewater treatment process.
Background
Caprolactam is a raw material for producing nylon-6, and the production and demand of caprolactam are continuously increasing with the development of industry. In the process of producing caprolactam, a large amount of organic wastewater which is difficult to degrade is generated, organic matters in the wastewater generally comprise cyclohexylamine peroxide, cyclohexane azo, anthraquinone toluene, cyclohexanone oxime and the like, and simultaneously, a large amount of ammonium sulfate salt serving as a byproduct is also contained in the wastewater. Because the organic matter content in the wastewater is high, and the components are relatively complex, the treatment pressure is high. In actual operation, even if the multi-stage biochemical treatment technologies of primary air floatation, secondary anaerobic and aerobic treatment and tertiary advanced treatment (such as adsorption, membrane, coagulation and the like) are adopted for harmless treatment, the wastewater still has high chroma, and indexes such as COD value, total nitrogen content and the like can not reach the national discharge standard.
In the patent, the publication number is CN108275825A, caprolactam oximation wastewater enters a pH adjusting tank for pH value adjustment, then enters a strong oxidation tank for oxidation treatment, then enters a fixed bed reactor for further catalytic degradation after treatment, and finally is discharged after reaching the standard after being treated by a biochemical treatment system. According to the technical scheme, a plurality of technical means of strong oxidation, catalytic degradation and biochemical treatment are combined to treat caprolactam sewage, so that the pressure of biochemical treatment is reduced, but strong oxidants such as perchlorate and peroxide are required to be added in the strong oxidation process, so that the cost is high, and meanwhile, a large amount of salt generated after the oxidant reacts is introduced into the wastewater, so that certain influence is caused on the recovery of ammonium sulfate in the wastewater; meanwhile, because the organic matter components in the sewage are relatively complex, the subsequent catalytic degradation process is difficult to carry out more thorough degradation on the organic matter.
The patent with publication number CN112174423A provides a method for treating caprolactam production wastewater, which comprises the steps of firstly carrying out normal pressure feeding distillation treatment on the caprolactam production wastewater to obtain ammonium sulfate crystals, distillation condensate and distillation residual liquid, then recovering the ammonium sulfate crystals, recovering an upper organic layer of the distillation residual liquid, and finally introducing lower layer waste liquid of the distillation residual liquid and the distillation residual liquid into a biochemical tank for harmless treatment. The method recovers ammonium sulfate salt and organic matters in the caprolactam production wastewater to improve the resource utilization rate, but the wastewater has high-concentration organic matters during distillation, the purity of ammonium sulfate crystals is poor, and the lower layer waste liquid of the distillation residual liquid contains high-concentration organic impurities and salt, and the lower layer waste liquid is introduced into a biochemical pool to be directly treated and is difficult to reach the discharge standard.
The patent publication No. CN109205832A provides a method for treating caprolactam ammoximation production process wastewater, which comprises treating caprolactam wastewater with adsorbent resin, and introducing the treated wastewater into downstream processes. The scheme reduces the pressure of downstream biochemical treatment by a resin adsorption method, and the operation cost is reduced because the adsorption resin can be repeatedly used after being eluted. The problem of this patent is that although the adsorption resin can adsorb more than 85% of organic matters in the wastewater, the organic matter concentration of caprolactam wastewater is high, the resin is easily saturated quickly, the treatment efficiency is affected, and the desorption liquid containing organic matters and desorption agent generated after the saturated resin is desorbed is difficult to treat, and the treatment process is additionally increased.
Disclosure of Invention
In order to solve the problems, the invention provides a caprolactam production wastewater treatment process, in particular to the treatment of caprolactam ammoximation production process wastewater, the process does not need to adopt a strong oxidant with higher cost, no new impurities are introduced due to the addition of the oxidant in the oxidation process, more than 95 percent of organic matters can be degraded in the oxidation process, the pressure of subsequent biochemical treatment is greatly reduced, meanwhile, the invention can recover ammonium sulfate in the wastewater with higher purity, and the energy consumption is lower during evaporation and crystallization.
In order to achieve the purpose, the invention adopts the following technical scheme:
a caprolactam production wastewater treatment process comprises the following steps:
s1, introducing the caprolactam wastewater and an oxidant into an oxidation treatment unit filled with a catalyst, and adjusting the temperature and pressure of the oxidation treatment unit to enable the caprolactam wastewater and the oxidant to react under the subcritical water condition to obtain an oxidation treatment liquid;
s2, introducing the oxidation treatment liquid into a concentration treatment unit, and obtaining a concentrated liquid and a permeate liquid by adopting a reverse osmosis method;
s3, introducing the concentrated solution into an evaporation treatment unit, carrying out evaporation crystallization to obtain ammonium sulfate crystals, residual liquid and condensate, and recovering the ammonium sulfate crystals;
s4, introducing the permeate, the residual liquid and the condensate into a biochemical treatment unit for biochemical treatment.
Further, the oxidant is oxygen-enriched air with the oxygen content of 22% -50%.
In the existing technology for removing organic matters in wastewater by strong oxidation, strong oxidants such as hydrogen peroxide, sodium chlorate, sodium hypochlorite, sodium perchlorate, sodium persulfate, ammonium persulfate and the like are generally adopted to match with corresponding catalysts, and the solution environment is adjusted to be acidic to carry out oxidation treatment on the organic matters in the wastewater, so that the organic matters are decomposed into final oxidation products such as carbon dioxide, water and the like or micromolecular organic matter intermediates. In the above oxidation process, the strong oxidant is expensive, and a high oxidant concentration is required to obtain a high organic oxidation rate, and in terms of hydrogen peroxide, the amount of hydrogen peroxide added is 255kg or more (30% by mass concentration) theoretically, calculated from the COD removal rate in wastewater to 90.0% (raw water is 40000 mg/L), so that the total treatment cost is not less than 300.00 yuan/m3It is expensive and it is difficult to achieve a predetermined removal efficiency only by the fenton method of adding hydrogen peroxide. On the other hand, when a salt with strong oxidizing property, such as sodium hypochlorite, is used, sodium chloride is generated after the sodium hypochlorite and the organic matter undergo redox reaction, which leads to the introduction of new impurities into the wastewater, and when ammonium sulfate is recovered by subsequent evaporative crystallization, the newly introduced salt has a certain influence on the purity of the ammonium sulfate. Finally, the reaction is carried out under an acidic condition, so that the requirement on the corrosion resistance of the inner wall of the reaction kettle is high, and a strong oxidant exists under the reaction condition, so that the corrosion degree of the inner wall is further improved. Especially for caprolactam ammoximation production process, ammonia water exists in the waste water to form alkaliIn order to adjust the solution system to be acidic, a reagent such as sulfuric acid needs to be added, which further increases the cost.
The scheme of the invention adopts a subcritical water oxidation method to treat the wastewater. The subcritical water oxidation method is that water is heated to 120-320 ℃ under a high pressure condition to form a high-pressure high-temperature liquid environment, the dissolution and the dispersibility of an oxidant (namely oxygen) and organic matters in the water are greatly improved under the environment, so that the reaction activity between the oxidant and the organic matters reaches a higher level, the organic matters are oxidized to generate harmless components such as carbon dioxide, water, nitrogen and the like, and a small part of the harmless components are not completely oxidized and are degraded into small-molecular-weight oxidation intermediate products which are easy to carry out biochemical treatment. Compared with the scheme adopting a strong oxidant, the subcritical water oxidation method enables air or oxygen-enriched air (pure oxygen can also be used) with extremely low cost to be adopted in the oxidation process by adjusting parameters such as temperature, pressure and the like in the oxidation tower, and no new impurity components such as metal ions, sulfate radicals, chloride ions and the like are introduced in the reaction process of oxygen and organic matters, so that in the subsequent ammonium sulfate evaporation crystallization recovery process, the ammonium sulfate crystals contain fewer impurity salts, and the purification cost is lower. Meanwhile, the subcritical water oxidation method does not need to be carried out under an acidic condition, so that the process is simpler when the caprolactam ammoximation production process wastewater is treated, the pH is not required to be adjusted by additionally adding acid, and from another aspect, the caprolactam ammoximation production process wastewater is alkaline, so that the corrosion of the acid on the inner wall of the reaction kettle under the subcritical water condition can be effectively avoided, and the equipment maintenance cost is reduced.
The oxidation treatment liquid treated by the subcritical water oxidation method is introduced into an evaporation treatment unit, the evaporation treatment unit is provided with a reverse osmosis concentration pretreatment process, a semipermeable membrane which is an important component of reverse osmosis only allows water molecules or solutes smaller than the water molecules to pass through, and water in the oxidation treatment liquid can permeate to the other side by pressurizing the oxidation treatment liquid, so that the oxidation treatment liquid is concentrated. The salt concentration in the wastewater of the general caprolactam ammoximation production process is only 2-4%, the salt concentration can be improved to 8-15% by a reverse osmosis method, the water evaporation amount required in the evaporation crystallization process can be reduced by 25-75%, and the treatment amount and energy consumption of evaporation crystallization are greatly reduced. Because the subcritical water oxidation method is adopted to remove most organic matters in the wastewater, when the subsequent reverse osmosis method is used for concentration, on one hand, a reverse osmosis membrane is not polluted due to the existence of the organic matters, the concentration efficiency is reduced, on the other hand, the organic matters are not concentrated in ammonium sulfate crystals due to the concentration process, the ammonium sulfate recovery is not influenced, meanwhile, because the oxidant is oxygen (or oxygen in air), other inorganic salt components contained in the ammonium sulfate are less, and the subsequent purification processes such as recrystallization and the like are simpler.
And finally, introducing the condensate and residual liquid in the evaporative crystallization process and permeate liquid in the reverse osmosis process into a biochemical treatment unit, performing harmless treatment by the biochemical treatment unit, and discharging after reaching the standard.
And further, before the caprolactam wastewater is introduced into the oxidation treatment unit, benzene is used for extraction, and the extracted caprolactam wastewater and an oxidant are introduced into the oxidation treatment unit together.
Further, the oxidation treatment unit comprises one or more oxidation towers connected in series, preferably two oxidation towers connected in series.
Furthermore, the addition amount of the oxidant is 1.05-1.5 times of the COD of the caprolactam wastewater.
Furthermore, the oxidation treatment liquid is partially refluxed and is led into the oxidation treatment unit together with caprolactam waste water for cyclic oxidation.
Further, in the caprolactam waste water introduced into the oxidation treatment unit, the raw caprolactam waste water feeding amount is: the reflux amount of the oxidation treatment liquid is =1 (0.01-5).
In order to improve the COD removal rate of the wastewater in the oxidation treatment unit, a plurality of oxidation processes are generally arranged in series, and the wastewater is subjected to a plurality of rounds of oxidation treatment, but with the increase of the oxidation processes, the occupied area of equipment is increased, and the construction cost is also increased. The larger the reflux amount is, the more thoroughly the organic matter in the oxidation treatment liquid is decomposed, and therefore the reflux amount can be adjusted in accordance with the detected amount of COD in the oxidation treatment liquid, and generally, COD in the oxidation treatment liquid may be 10% or less or 5% or less of COD in caprolactam wastewater.
When the oxidation treatment liquid is led out from the oxidation treatment unit, the oxidation treatment liquid is firstly treated by a gas-liquid separator and then led into a concentration treatment unit or refluxed; and a spraying adsorption device is arranged in the gas-liquid processor.
Further, the spraying liquid of the spraying adsorption device is a sulfuric acid solution with the weight percent of 5-10%.
For caprolactam ammoximation production process, ammonia water can be remained in the waste water, and the ammonia water in the oxidation treatment liquid after high-temperature treatment is easy to gasify and overflow, so that the oxidation treatment liquid needs to be treated by a gas-liquid separator when being led out to absorb volatile harmful components in gas.
Further, the pH of the permeate, the residual liquid and the condensate is adjusted to 6.5-7.5 by a neutralizing agent and then introduced into a biochemical treatment unit.
In conclusion, the scheme of the invention has the following beneficial effects:
1. compared with the method adopting strong oxidants such as hydrogen peroxide, sodium hypochlorite and the like to oxidize, the method adopting subcritical water oxidation method to treat caprolactam can adopt air, oxygen-enriched air or oxygen as the oxidant, so that the cost is greatly reduced, and the degradation rate of organic matters can reach a level of more than 90%.
2. The subcritical water oxidation method adopted by the invention has obvious advantages when aiming at the wastewater of caprolactam ammoximation production process, acid is not required to be added in the oxidation process to adjust the pH value, and meanwhile, because the solution is in an alkaline condition, the corrosion on the inner wall of the reaction kettle is greatly reduced, and the equipment maintenance cost is reduced.
3. According to the method, air, oxygen-enriched air or oxygen is used as an oxidant, new salt-forming ions are not introduced in the oxidation process, and the purity of ammonium sulfate crystals is higher in the subsequent ammonium sulfate crystallization recovery process.
4. When the method is used for recovering the ammonium sulfate, firstly, a large amount of water is removed by adopting a reverse osmosis method, so that the concentration of the ammonium sulfate is increased from 2-4% to 8-15%, the amount of the solvent required to be evaporated during evaporation and crystallization is greatly reduced, and the energy consumption is reduced.
5. Aiming at the wastewater of the caprolactam ammoximation production process, the oxidation treatment solution is treated in a dilute sulfuric acid spraying mode, so that ammonia water in the oxidation treatment solution is adsorbed and reacted to obtain ammonium sulfate, meanwhile, the dilute sulfuric acid can also adjust the pH of the oxidation treatment solution to an acidic level of 2.0-6.5, the hydrolysis of the ammonium sulfate in the evaporation crystallization process is inhibited, and the recovery rate of the ammonium sulfate is improved.
Detailed Description
The invention provides a caprolactam production wastewater treatment process to solve the problem of high-concentration organic matter treatment in caprolactam production wastewater and the problem of ammonium sulfate recovery therein, and particularly has obvious advantages for a caprolactam ammoximation production process, and preferred embodiments of the invention are further described by the following examples.
Example 1
In this embodiment, the wastewater generated in a 20t/h ammoximation liquid phase rearrangement process for producing caprolactam with a COD concentration of about 45000mg/L and containing ammonium sulfate of about 4% is treated by the following specific steps:
s1, introducing the caprolactam wastewater into an extraction unit, adding benzene into the extraction unit, and extracting the wastewater;
s2, mixing the extracted caprolactam wastewater (underflow) with oxygen-enriched air with the oxygen content of 35% (the actual introduction amount of oxygen is 1.2 times of the COD of the caprolactam wastewater) through a mixer, then preheating through a plurality of sets of sleeve heaters, wherein the heat source of each sleeve heater is from oxidation treatment liquid (heated by saturated steam when the machine is started) led out from an oxidation treatment unit, so that the temperature is raised to over 180 ℃, and then introducing the heated caprolactam wastewater and the oxygen-enriched air into an oxidation tower of the oxidation treatment unit; the oxidation tower is filled with filler and oxidant, the pressure in the tower is set to be 8MPa, and the reaction temperature is set to be 230 ℃; the oxidation treatment unit comprises two oxidation towers connected in series, partial oxidation treatment liquid at the outlet end of the oxidation treatment unit reflows to the inlet end of the oxidation treatment unit, is mixed with extracted caprolactam wastewater and is reintroduced into the oxidation tower, and the reflux amount of the oxidation treatment liquid is as follows: caprolactam waste water amount =0.3: 1.
S3, introducing the oxidation treatment liquid which is led out from the oxidation treatment unit and does not participate in the reflux into the gas-liquid separator, spraying a dilute sulfuric acid solution with a concentration of 6% onto the oxidation treatment liquid by a spraying device in the gas-liquid separator, and controlling the flow rate and spraying amount of the oxidation treatment liquid so that the pH of the oxidation treatment liquid led out from the gas-liquid separator is 3.5.
S4, introducing the oxidation treatment liquid after the spray treatment into a concentration treatment unit, wherein the concentration treatment unit is provided with a reverse osmosis membrane, applying a pressure of about 41bar to the oxidation treatment liquid to make the solvent permeate and seep from the other side of the reverse osmosis membrane, and the membrane flux is 16L/(m)2H) until the volume of the oxidation treatment solution is concentrated to 50%, obtaining a concentrated solution and a permeate.
S5, introducing the concentrated solution into an evaporation treatment unit, heating to evaporate the solution to obtain ammonium sulfate crystals, and recovering the ammonium sulfate crystals, the condensate and the residual solution.
And S6, adjusting the pH of the permeate, the condensate and the residual liquid to 6.5-7.5 by a neutralizing agent, and introducing the permeate, the condensate and the residual liquid into a biochemical treatment unit for biochemical treatment by microorganisms.
Example 2
In this embodiment, waste water generated from a 23t/h ammoximation liquid phase rearrangement process for producing caprolactam is treated, wherein the COD concentration is about 50000mg/L, and the waste water contains about 4% of ammonium sulfate, and the treatment method comprises the following specific steps:
s1, introducing the caprolactam wastewater into an extraction unit, adding benzene into the extraction unit, and extracting the wastewater;
s2, mixing the extracted caprolactam wastewater (underflow) with oxygen-enriched air with the oxygen content of 40% (the actual introduction amount of oxygen is 1.3 times of the COD of the caprolactam wastewater) through a mixer, then preheating through a plurality of sets of sleeve heaters, wherein the heat source of each sleeve heater is from oxidation treatment liquid (heated by saturated steam when the machine is started) led out from an oxidation treatment unit, so that the temperature is raised to be over 180 ℃, and then leading the heated caprolactam wastewater and the oxygen-enriched air into an oxidation tower of the oxidation treatment unit; the oxidation tower is filled with filler and oxidant, the pressure in the tower is set to be 8.5MPa, and the reaction temperature is set to be 240 ℃; the oxidation treatment unit comprises two oxidation towers connected in series, partial oxidation treatment liquid at the outlet end of the oxidation treatment unit reflows to the inlet end of the oxidation treatment unit, is mixed with extracted caprolactam wastewater and is reintroduced into the oxidation tower, and the reflux amount of the oxidation treatment liquid is as follows: caprolactam waste water amount =0.3: 1.
S3, introducing the oxidation treatment liquid which is led out from the oxidation treatment unit and does not participate in the reflux into the gas-liquid separator, spraying a dilute sulfuric acid solution with a concentration of 6% onto the oxidation treatment liquid by a spraying device in the gas-liquid separator, and controlling the flow rate and spraying amount of the oxidation treatment liquid so that the pH of the oxidation treatment liquid led out from the gas-liquid separator is 3.5.
S4, introducing the oxidation treatment liquid after the spray treatment into a concentration treatment unit, wherein the concentration treatment unit is provided with a reverse osmosis membrane, applying a pressure of about 41bar to the oxidation treatment liquid to make the solvent permeate and seep from the other side of the reverse osmosis membrane, and the membrane flux is 16L/(m)2H) until the volume of the oxidation treatment solution is concentrated to 50%, obtaining a concentrated solution and a permeate.
S5, introducing the concentrated solution into an evaporation treatment unit, heating to evaporate the solution to obtain ammonium sulfate crystals, and recovering the ammonium sulfate crystals, the condensate and the residual solution.
And S6, adjusting the pH of the permeate, the condensate and the residual liquid to 6.5-7.5 by a neutralizing agent, and introducing the permeate, the condensate and the residual liquid into a biochemical treatment unit for biochemical treatment by microorganisms.
Comparative example 1
The comparative example treats wastewater generated by a caprolactam ammoximation liquid phase rearrangement production process and adopts a strong oxidant oxidation method for treatment. The method comprises the following specific steps:
s1, introducing the caprolactam wastewater into an extraction unit, adding benzene into the extraction unit, and extracting the wastewater;
s2, adding sulfuric acid into the extracted caprolactam wastewater (underflow), stirring or bubbling to adjust the pH value to about 5.0, adding hydrogen peroxide and sodium chlorate into the caprolactam wastewater, wherein the adding amount of ammonium chlorate equivalent oxygen is 1.2 times of the COD of the caprolactam wastewater, the adding amount of the hydrogen peroxide is 100ppm, introducing the mixed liquid into a strong oxidation tank, carrying out catalytic oxidation treatment by using an iron catalyst, and leading out after reacting for 25 min.
Comparative example 2
The comparative example is used for treating wastewater generated by a caprolactam ammoximation liquid phase rearrangement production process and adopts a resin adsorption method for treatment. The method comprises the following specific steps:
s1, introducing the caprolactam wastewater into an extraction unit, adding benzene into the extraction unit, and extracting the wastewater;
s2, mixing the extracted caprolactam waste water (bottom liquid) by 5m3The flow rate was adjusted to a flow rate of 1G, and the effluent was introduced into an adsorption column (adsorption column specification: 1200 x 3000mm, packed volume: 2.5 cubic meters) packed with a styrene macroporous adsorbent resin (XDA-1G, manufactured by seian blue advanced science and technology materials co., ltd.) and discharged after adsorption.
And (3) data comparison: the raw caprolactam waste water and the oxidized or resin-adsorbed caprolactam waste water in examples and comparative examples were sampled and measured for COD (mg/L) and BOD/COD (biodegradability, for evaluating the ease of biochemical treatment, the larger the value, the easier the biochemical treatment), and the results are shown in Table 1. The raw caprolactam waste water refers to caprolactam waste water after benzene extraction.
TABLE 1
As can be seen from Table 1, the method adopted by the invention has better effect in removing COD in caprolactam wastewater compared with the comparative example, and is more favorable for the subsequent biochemical treatment step because the subcritical water oxidation method has more thorough oxidative decomposition on organic matters and larger BOD/COD value.
The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.
Claims (10)
1. A caprolactam production wastewater treatment process comprises the following steps:
s1, introducing the caprolactam wastewater and an oxidant into an oxidation treatment unit filled with a catalyst, and adjusting the temperature and pressure of the oxidation treatment unit to enable the caprolactam wastewater and the oxidant to react under the subcritical water condition to obtain an oxidation treatment liquid;
s2, introducing the oxidation treatment liquid into a concentration treatment unit, and obtaining a concentrated liquid and a permeate liquid by adopting a reverse osmosis method;
s3, introducing the concentrated solution into an evaporation treatment unit, carrying out evaporation crystallization to obtain ammonium sulfate crystals, residual liquid and condensate, and recovering the ammonium sulfate crystals;
s4, introducing the permeate, the residual liquid and the condensate into a biochemical treatment unit for biochemical treatment.
2. The process for treating wastewater from caprolactam production according to claim 1, wherein: the oxidant is oxygen-enriched air with oxygen content of 22% -50%.
3. The process for treating wastewater from caprolactam production according to claim 1, wherein: and before the caprolactam wastewater is introduced into the oxidation treatment unit, benzene is used for extraction, and the extracted caprolactam wastewater and an oxidant are introduced into the oxidation treatment unit together.
4. The process for treating wastewater from caprolactam production according to claim 1, wherein: the oxidation treatment unit comprises two or more oxidation towers connected in series.
5. The process for treating wastewater from caprolactam production according to claim 1, wherein: the addition amount of the oxidant is 1.05-1.5 times of the COD of the caprolactam wastewater.
6. The process for treating wastewater from caprolactam production according to claim 1, wherein: and part of the oxidation treatment liquid reflows and is led into the oxidation treatment unit together with caprolactam wastewater for cyclic oxidation.
7. The process of claim 6, wherein the wastewater from caprolactam production comprises: the feeding amount of the primary caprolactam wastewater in the caprolactam wastewater introduced into the oxidation treatment unit is as follows: the reflux amount of the oxidation treatment liquid is =1 (0.01-5).
8. The process of claim 6, wherein the wastewater from caprolactam production comprises: when the oxidation treatment liquid is led out from the oxidation treatment unit, the oxidation treatment liquid is firstly treated by a gas-liquid separator and then led into a concentration treatment unit or refluxed; and a spraying adsorption device is arranged in the gas-liquid separator.
9. The process of claim 8, wherein the wastewater from caprolactam production comprises: the spraying liquid of the spraying adsorption device is 5-10 wt% of sulfuric acid solution.
10. The process for treating wastewater from caprolactam production according to claim 9, wherein: and regulating the pH of the permeate, the residual liquid and the condensate to 6.5-7.5 by using a neutralizing agent, and then introducing the permeate, the residual liquid and the condensate into a biochemical treatment unit.
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