CN115353237A - Process and system for realizing zero discharge and resource utilization of coking wastewater - Google Patents
Process and system for realizing zero discharge and resource utilization of coking wastewater Download PDFInfo
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- 238000004939 coking Methods 0.000 title claims abstract description 52
- 239000002351 wastewater Substances 0.000 title claims abstract description 47
- 238000000034 method Methods 0.000 title claims abstract description 24
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 231
- 238000001728 nano-filtration Methods 0.000 claims abstract description 114
- 238000001223 reverse osmosis Methods 0.000 claims abstract description 98
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 80
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims abstract description 67
- 229910052938 sodium sulfate Inorganic materials 0.000 claims abstract description 67
- 235000011152 sodium sulphate Nutrition 0.000 claims abstract description 67
- 238000002425 crystallisation Methods 0.000 claims abstract description 62
- 230000008025 crystallization Effects 0.000 claims abstract description 62
- 238000001704 evaporation Methods 0.000 claims abstract description 61
- 230000008020 evaporation Effects 0.000 claims abstract description 61
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 45
- 238000005352 clarification Methods 0.000 claims abstract description 42
- 239000011780 sodium chloride Substances 0.000 claims abstract description 40
- 238000007710 freezing Methods 0.000 claims abstract description 33
- 230000008014 freezing Effects 0.000 claims abstract description 33
- 238000000746 purification Methods 0.000 claims abstract description 30
- 238000000108 ultra-filtration Methods 0.000 claims abstract description 30
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims abstract description 29
- 238000001179 sorption measurement Methods 0.000 claims abstract description 29
- 238000001953 recrystallisation Methods 0.000 claims abstract description 28
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 26
- 230000003197 catalytic effect Effects 0.000 claims abstract description 25
- 230000003647 oxidation Effects 0.000 claims abstract description 24
- 150000003839 salts Chemical class 0.000 claims abstract description 24
- 150000002500 ions Chemical class 0.000 claims abstract description 22
- 239000011734 sodium Substances 0.000 claims abstract description 22
- 229910052708 sodium Inorganic materials 0.000 claims abstract description 22
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims abstract description 18
- 239000002253 acid Substances 0.000 claims abstract description 18
- -1 silicon ions Chemical class 0.000 claims description 50
- 239000012528 membrane Substances 0.000 claims description 49
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 32
- 229910052710 silicon Inorganic materials 0.000 claims description 30
- 239000010703 silicon Substances 0.000 claims description 30
- 230000004907 flux Effects 0.000 claims description 21
- 239000011737 fluorine Substances 0.000 claims description 18
- 229910052731 fluorine Inorganic materials 0.000 claims description 18
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 16
- 239000000920 calcium hydroxide Substances 0.000 claims description 16
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 16
- 229920002401 polyacrylamide Polymers 0.000 claims description 16
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 16
- 229910052799 carbon Inorganic materials 0.000 claims description 15
- 238000004519 manufacturing process Methods 0.000 claims description 14
- 238000011282 treatment Methods 0.000 claims description 14
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical group [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 claims description 13
- 229910001424 calcium ion Inorganic materials 0.000 claims description 13
- 239000000047 product Substances 0.000 claims description 13
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 12
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 claims description 12
- 229910000360 iron(III) sulfate Inorganic materials 0.000 claims description 12
- 239000012452 mother liquor Substances 0.000 claims description 12
- 239000002244 precipitate Substances 0.000 claims description 12
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 11
- 239000006004 Quartz sand Substances 0.000 claims description 10
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 10
- RHZUVFJBSILHOK-UHFFFAOYSA-N anthracen-1-ylmethanolate Chemical compound C1=CC=C2C=C3C(C[O-])=CC=CC3=CC2=C1 RHZUVFJBSILHOK-UHFFFAOYSA-N 0.000 claims description 10
- 239000003830 anthracite Substances 0.000 claims description 10
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 claims description 9
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 claims description 9
- 239000000084 colloidal system Substances 0.000 claims description 8
- 238000004064 recycling Methods 0.000 claims description 8
- 239000011552 falling film Substances 0.000 claims description 7
- 229910001425 magnesium ion Inorganic materials 0.000 claims description 7
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 6
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 claims description 6
- 239000000347 magnesium hydroxide Substances 0.000 claims description 6
- 229910001862 magnesium hydroxide Inorganic materials 0.000 claims description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 5
- 239000003054 catalyst Substances 0.000 claims description 5
- 230000014759 maintenance of location Effects 0.000 claims description 5
- 238000011084 recovery Methods 0.000 claims description 4
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 claims description 3
- VXAUWWUXCIMFIM-UHFFFAOYSA-M aluminum;oxygen(2-);hydroxide Chemical class [OH-].[O-2].[Al+3] VXAUWWUXCIMFIM-UHFFFAOYSA-M 0.000 claims description 3
- 239000011630 iodine Substances 0.000 claims description 3
- 229910052740 iodine Inorganic materials 0.000 claims description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 229910001437 manganese ion Inorganic materials 0.000 claims description 3
- 239000002245 particle Substances 0.000 claims description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 4
- 239000011575 calcium Substances 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 description 2
- SMWDFEZZVXVKRB-UHFFFAOYSA-N Quinoline Chemical compound N1=CC=CC2=CC=CC=C21 SMWDFEZZVXVKRB-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 239000005416 organic matter Substances 0.000 description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229920000515 polycarbonate Polymers 0.000 description 2
- 239000004417 polycarbonate Substances 0.000 description 2
- 125000005575 polycyclic aromatic hydrocarbon group Chemical group 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000004065 wastewater treatment Methods 0.000 description 2
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 1
- ZMZDMBWJUHKJPS-UHFFFAOYSA-M Thiocyanate anion Chemical compound [S-]C#N ZMZDMBWJUHKJPS-UHFFFAOYSA-M 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- ZMZDMBWJUHKJPS-UHFFFAOYSA-N hydrogen thiocyanate Natural products SC#N ZMZDMBWJUHKJPS-UHFFFAOYSA-N 0.000 description 1
- 231100001240 inorganic pollutant Toxicity 0.000 description 1
- 230000000813 microbial effect Effects 0.000 description 1
- 239000002957 persistent organic pollutant Substances 0.000 description 1
- 150000002989 phenols Chemical class 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000010802 sludge Substances 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
-
- 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
- C02F1/28—Treatment of water, waste water, or sewage by sorption
-
- 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
- C02F1/42—Treatment of water, waste water, or sewage by ion-exchange
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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
- C02F1/44—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
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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
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
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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
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/444—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by ultrafiltration or microfiltration
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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
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/02—Softening water by precipitation of the hardness
- C02F5/06—Softening water by precipitation of the hardness using calcium compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/08—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents
- C02F5/10—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents using organic substances
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- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention relates to a process and a system for realizing zero discharge and resource utilization of coking wastewater, wherein the system comprises a softening clarification tank, a multi-media filter A, an ultrafiltration device, a primary reverse osmosis device, an ozone catalytic oxidation tower, an activated carbon adsorption tower, a concentrated water softening clarification tank, a multi-media filter B, a weak acid sodium type ion exchanger, a low-pressure nanofiltration device, a high-pressure nanofiltration device, a secondary reverse osmosis device, a concentration reverse osmosis device, a purification nanofiltration device, a sodium chloride evaporation and crystallization system, a sodium sulfate evaporation and freezing crystallization system, a recrystallization system and a mixed salt evaporation and crystallization device; compared with the prior art, the invention has the advantages that the whole operation of the system is more stable, and the multi-stage salt design is adopted, so that the yield and the quality of the product salt are improved.
Description
Technical Field
The invention relates to the field of coking wastewater purification treatment, in particular to a process and a system for realizing zero discharge and resource utilization of coking wastewater.
Background
The coking wastewater mainly comes from the processes of coking, gas purification, byproduct recovery and refining, and contains organic pollutants such as phenols, pyridine, quinoline, polycyclic Aromatic Hydrocarbons (PAHs) and the like besides high-concentration inorganic pollutants such as ammonia, cyanide, thiocyanide and the like. After advanced treatment including anaerobic-anoxic-aerobic biochemical treatment, adsorption, oxidation and other processes, biodegradable and most of nonbiodegradable organic matters in the coking wastewater are basically removed. The effluent can meet the index requirements of direct discharge in table 2 in the discharge Standard of pollutants for coking chemical industry (GB 16171-2012).
However, with the increase of the requirement of the discharge of the coke per ton and the urgent need of the coking enterprises for the utilization of water resources, the recycling and zero discharge of the coking wastewater gradually become the target of wastewater treatment of the coking enterprises. Because the water quality of the coking wastewater is very complex, the coking wastewater after advanced treatment still has factors influencing the recycling and the operation of a zero-emission system, such as organic matter content, hardness, silicon content, fluorine ion content and the like. The existing process for realizing zero discharge of coking wastewater generally has the problems of incomplete pretreatment, unreasonable process system connection and the like, and often causes the faults of membrane system fouling, evaporation system scaling and the like.
In view of this, it is necessary to develop a new process which is feasible in technology, stable in operation and reliable in effect and can realize zero discharge and resource utilization of coking wastewater.
Disclosure of Invention
The invention provides a process and a system for realizing zero discharge and resource utilization of coking wastewater, compared with the prior art, the whole operation of the system is more stable, and the multi-level salt design is adopted, so that the yield and the quality of product salt are improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
a process for realizing zero discharge and resource utilization of coking wastewater comprises the following steps:
(1) The coking wastewater after advanced treatment firstly enters a softening clarification tank, calcium hydroxide, sodium carbonate, polymeric ferric sulfate and polyacrylamide are sequentially added into the softening clarification tank, calcium ions in water form calcium carbonate precipitates, magnesium ions form magnesium hydroxide precipitates, and silicon ions and fluorine ions in water are removed;
(2) The effluent of the softening and clarifying tank enters a multi-media filter A and an ultrafiltration device to remove suspended matters and colloid in the water, thereby meeting the water inlet requirement of reverse osmosis;
(3) After the ultrafiltration effluent is pressurized by a pump, the ultrafiltration effluent enters a first-stage reverse osmosis device, and the produced water enters a water producing pool for recycling;
(4) The first-stage reverse osmosis concentrated water sequentially enters an ozone catalytic oxidation tower and an active carbon adsorption tower to remove organic matters in the water;
(5) The water discharged from the active carbon adsorption tower enters a concentrated water softening clarification tank, calcium hydroxide, sodium carbonate, polymeric ferric sulfate and polyacrylamide are sequentially added into the concentrated water softening clarification tank, calcium ions in the water form calcium carbonate precipitates, magnesium ions form magnesium hydroxide precipitates, and silicon ions and fluorine ions in the water are removed; the effluent of the concentrated water softening clarification tank enters a multi-media filter B to remove suspended matters and colloids in the water, and the effluent of the multi-media filter enters a weak acid sodium type ion exchanger to completely remove calcium ions and magnesium ions in the water;
(6) The outlet water of the weak acid sodium type ion exchanger is pressurized by a pump and then sent into a low-pressure nanofiltration device, nanofiltration concentrated water enters a high-pressure nanofiltration device, the concentration of sodium sulfate in the water is further improved, and the high-pressure nanofiltration concentrated water enters a sodium sulfate evaporation, freezing, crystallization and recrystallization system;
(7) The water produced by the low-pressure nanofiltration device and the water produced by the high-pressure nanofiltration device are further concentrated by a secondary reverse osmosis device and a concentration reverse osmosis device, the secondary reverse osmosis water and the concentration reverse osmosis water are recycled in a water production pool, and the concentrated reverse osmosis concentrated water enters a purification nanofiltration device;
(8) The purified nanofiltration produced water flows back to the water inlet end of the low-pressure nanofiltration device, and the purified nanofiltration concentrated water enters a sodium chloride evaporation crystallization system;
(9) Sodium sulfate evaporation and freezing crystallization, and the mother liquor of recrystallization and the mother liquor of sodium chloride evaporation crystallization enter a mixed salt evaporation crystallization device to produce mixed salt.
In the step (1), the coking wastewater subjected to advanced treatment has the following water quality indexes: COD concentration is 60-80 mg/L, TDS concentration is 3500-5000 mg/L, chloride ion concentration is 1000-2000 mg/L, sulfate ion concentration is 800-2000 mg/L; adding calcium hydroxide and sodium carbonate into the softening clarification tank according to the hardness and alkalinity of the coking wastewater to control the hardness of water to be below 100 mg/L; meanwhile, 50-100 mg/L of polymeric ferric sulfate and 2-5 mg/L of polyacrylamide are added, so that the concentration of silicon ions in water is reduced to be below 10mg/L, and the concentration of fluorine ions is reduced to be below 10mg/L.
In the step (2), quartz sand and anthracite are filled in the multi-medium filter A, and the running flow rate is 8-10 m/h; the membrane flux of the ultrafiltration membrane in the ultrafiltration device is 35 to 45L/m 2 h; after being filtered by a multi-medium filter and an ultrafiltration device, the turbidity of the water is less than 0.5NTU, and the SDI is less than 3.
In the step (3), the membrane flux of the first-stage reverse osmosis membrane in the first-stage reverse osmosis device is 15-20L/m 2 h, adopting one-stage two-section or one-stage three-section arrangement, and controlling the recovery rate of the first-stage reverse osmosis at 75-80%.
In the step (4), a catalyst which takes activated aluminum dioxide as a carrier and contains iron ions and manganese ions is added into the ozone catalytic oxidation tower, the hydraulic retention time of the catalytic oxidation tower is 1-2 h, and the adding concentration ratio of ozone to COD in water is 1:1-3:1; the indexes of the granular activated carbon adopted in the activated carbon adsorption tower are as follows: the particle size is 8-30 meshes, the iodine adsorption value is 600-800 mg/g, the water content is less than or equal to 5 percent, and the strength is more than or equal to 90 percent; after passing through an ozone catalytic oxidation tower and an active carbon adsorption device, the COD concentration of the effluent is less than 100mg/L.
In the step (5), calcium hydroxide and sodium carbonate are added into the concentrated water softening clarification tank according to the hardness and alkalinity of the coking wastewater, so that the hardness of water is controlled below 100mg/L, and simultaneously, 50-100 mg/L of polymeric ferric sulfate and 2-5 mg/L of polyacrylamide are added, so that the concentration of silicon ions in the water is reduced to below 10mg/L, and the concentration of fluorine ions is reduced to below 10mg/L; filling quartz sand and anthracite into the multi-medium filter B, and enabling the running flow speed to be 8-10 m/h; the running flow rate of the weak acid sodium type ion exchanger is less than 20m/h; the total hardness of effluent is less than 0.5mg/L.
In the step (6), the membrane flux of the low-pressure nanofiltration membrane in the low-pressure nanofiltration device is 15 to 20L/m 2 h, adopting a first-stage two-stage arrangement, wherein the water yield is 65-75%; the membrane flux of the high-pressure nanofiltration membrane in the high-pressure nanofiltration device is 10-15L/m 2 h, adopting one-stage arrangement, wherein the water yield is 50-60%; the indexes of the high-pressure nanofiltration concentrated water are as follows: TDS concentration is 80000-120000 mg/L, silicon ion concentration is less than 10mg/L, and fluorine ion concentration is less than 10mg/L; the sodium sulfate evaporation, freezing, crystallization and recrystallization system comprises: a sodium sulfate falling film concentrator, a sodium sulfate evaporation crystallizer, a sodium sulfate freezing crystallizer and a sodium sulfate re-crystallizer; the content of sodium sulfate in the product is more than 98.5 percent.
In the step (7), the membrane flux of the secondary reverse osmosis membrane in the secondary reverse osmosis device is 10-15L/m 2 h, adopting a first-stage two-stage arrangement, wherein the water yield is 65-75%; the membrane flux of the concentrated reverse osmosis membrane in the concentrated reverse osmosis device is 10 to 15L/m 2 h, adopting a first-stage two-stage arrangement, wherein the water yield is 50-60%; the sodium chloride evaporative crystallization system comprises a sodium chloride evaporative crystallizer, and the content of sodium chloride in a product is more than 98.5%.
In the step (8), the membrane flux of the purification nanofiltration membrane in the purification nanofiltration device is 10 to 15L/m 2 h, adopting one-stage arrangement, wherein the water production indexes are as follows: TDS concentration is 70000-80000 mg/L, silicon ion concentration is less than 60mg/L, and fluorine ion concentration is less than 60mg/L.
A system for realizing zero discharge and resource utilization of coking wastewater comprises a softening clarification tank, a multi-media filter A, an ultrafiltration device, a primary reverse osmosis device, an ozone catalytic oxidation tower, an activated carbon adsorption tower, a concentrated water softening clarification tank, a multi-media filter B, a weak acid sodium type ion exchanger, a low-pressure nanofiltration device, a high-pressure nanofiltration device, a secondary reverse osmosis device, a concentration reverse osmosis device, a purification nanofiltration device, a sodium chloride evaporation crystallization system, a sodium sulfate evaporation and freezing crystallization system, a recrystallization system and a mixed salt evaporation crystallization device;
the softening clarification tank, the multi-media filter A, the ultrafiltration device and the primary reverse osmosis device are sequentially connected through pipelines, a concentrated water outlet of the primary reverse osmosis device is sequentially connected with the ozone catalytic oxidation tower, the activated carbon adsorption tower, the concentrated water softening clarification tank, the multi-media filter B, the weak acid sodium type ion exchanger and the low-pressure nanofiltration device through pipelines, and a produced water outlet of the primary reverse osmosis device is connected with the water production tank through a pipeline; a concentrated water outlet of the low-pressure nanofiltration device is sequentially connected with the high-pressure nanofiltration device and a sodium sulfate evaporation, freezing, crystallization and recrystallization system through pipelines; a water outlet of the low-pressure nanofiltration device is connected with a secondary reverse osmosis device through a pipeline, and a concentrated water outlet of the secondary reverse osmosis device is sequentially connected with a concentration reverse osmosis device and a purification nanofiltration device through pipelines; a concentrated water outlet of the purification nanofiltration device is connected with a sodium chloride evaporation crystallization system through a pipeline; a water outlet of the purification nanofiltration device is connected with a water inlet of the low-pressure nanofiltration device through a pipeline; a mother liquor outlet of the sodium sulfate evaporation and freezing crystallization and recrystallization system and a mother liquor outlet of the sodium chloride evaporation crystallization system are respectively connected with a mixed salt evaporation crystallization device through pipelines; the sodium sulfate evaporation, freezing crystallization and recrystallization system comprises a sodium sulfate falling film concentrator, a sodium sulfate evaporation crystallizer, a sodium sulfate freezing crystallizer and a sodium sulfate crystallizer; the sodium chloride evaporative crystallization system comprises a sodium chloride evaporative crystallizer.
Compared with the prior art, the invention has the beneficial effects that:
1) Compared with the prior art, the whole operation of the system is more stable; the main pollution of the operation of the membrane system is organic matter pollution blockage, microbial pollution and scaling; according to the invention, measures for removing organic matters and removing hard silicon are arranged in different links, so that the stable operation of each device in the system can be ensured, and the cleaning period and the replacement period of the membrane are reduced;
2) The multi-level salt design is adopted, so that the salt yield and quality of the product are improved; the yield of sodium sulfate crystal salt and sodium chloride crystal salt is ensured through the multi-stage salt separation system design of low-pressure nanofiltration, high-pressure nanofiltration and purification nanofiltration, and the product purity is high; thereby realizing the maximization of the resource utilization of the coking wastewater.
Drawings
FIG. 1 is a process flow diagram for realizing zero discharge and resource utilization of coking wastewater.
Detailed Description
The following further describes embodiments of the present invention in conjunction with the attached figures:
as shown in figure 1, the process for realizing zero discharge and resource utilization of coking wastewater comprises the following steps:
(1) The coking wastewater after advanced treatment firstly enters a softening clarification tank, calcium hydroxide, sodium carbonate, polymeric ferric sulfate and polyacrylamide are sequentially added into the softening clarification tank, calcium ions in water form calcium carbonate precipitates, magnesium ions form magnesium hydroxide precipitates, and silicon ions and fluorine ions in water are removed;
(2) The effluent of the softening and clarifying tank enters a multi-medium filter A and an ultrafiltration device to remove suspended matters and colloid in the water, so that the water inlet requirement of reverse osmosis is met;
(3) The ultrafiltration effluent is pressurized by a pump and then enters a first-stage reverse osmosis device, and the produced water enters a water producing pool for recycling;
(4) The first-stage reverse osmosis concentrated water sequentially enters an ozone catalytic oxidation tower and an active carbon adsorption tower to remove organic matters in the water;
(5) The water discharged from the active carbon adsorption tower enters a concentrated water softening clarification tank, calcium hydroxide, sodium carbonate, polymeric ferric sulfate and polyacrylamide are sequentially added into the concentrated water softening clarification tank, calcium ions in the water form calcium carbonate precipitates, magnesium ions form magnesium hydroxide precipitates, and silicon ions and fluorine ions in the water are removed; the effluent of the concentrated water softening clarification tank enters a multi-media filter B to remove suspended matters and colloids in the water, and the effluent of the multi-media filter enters a weak acid sodium type ion exchanger to completely remove calcium ions and magnesium ions in the water;
(6) Pressurizing the effluent of the weak acid sodium type ion exchanger by a pump, then sending the effluent into a low-pressure nanofiltration device, feeding nanofiltration concentrated water into a high-pressure nanofiltration device, further increasing the concentration of sodium sulfate in the water, and feeding the high-pressure nanofiltration concentrated water into a sodium sulfate evaporation and freeze crystallization and recrystallization system;
(7) The water produced by the low-pressure nanofiltration device and the water produced by the high-pressure nanofiltration device are further concentrated by a secondary reverse osmosis device and a concentration reverse osmosis device, the secondary reverse osmosis water and the concentration reverse osmosis water are recycled in a water production pool, and the concentrated reverse osmosis concentrated water enters a purification nanofiltration device;
(8) The purified nanofiltration produced water flows back to the water inlet end of the low-pressure nanofiltration device, and the purified nanofiltration concentrated water enters a sodium chloride evaporation crystallization system;
(9) Sodium sulfate evaporation and freezing crystallization, and the mother liquor of recrystallization and the mother liquor of sodium chloride evaporation crystallization enter a mixed salt evaporation crystallization device to produce mixed salt.
In the step (1), the coking wastewater subjected to advanced treatment has the following water quality indexes: COD concentration is 60-80 mg/L, TDS concentration is 3500-5000 mg/L, chloride ion concentration is 1000-2000 mg/L, sulfate ion concentration is 800-2000 mg/L; adding calcium hydroxide and sodium carbonate into the softening clarification tank according to the hardness and alkalinity of the coking wastewater to control the hardness of water to be below 100 mg/L; meanwhile, 50-100 mg/L of polymeric ferric sulfate and 2-5 mg/L of polyacrylamide are added, so that the concentration of silicon ions in water is reduced to be below 10mg/L, and the concentration of fluorine ions is reduced to be below 10mg/L.
In the step (2), quartz sand and anthracite are filled in the multi-medium filter A, and the running flow speed is 8-10 m/h; the membrane flux of the ultrafiltration membrane in the ultrafiltration device is 35 to 45L/m 2 h; after being filtered by a multi-medium filter and an ultrafiltration device, the turbidity of the water is less than 0.5NTU, and SDI is less than 3.
In the step (3), the membrane flux of the first-stage reverse osmosis membrane in the first-stage reverse osmosis device is 15-20L/m 2 h, adopting one-stage two-section or one-stage three-section arrangement, and controlling the recovery rate of the first-stage reverse osmosis at 75-80%.
In the step (4), a catalyst which takes activated aluminum dioxide as a carrier and contains iron ions and manganese ions is added into the ozone catalytic oxidation tower, the hydraulic retention time of the catalytic oxidation tower is 1-2 h, and the adding concentration ratio of ozone to COD in water is 1:1-3:1; the indexes of the granular activated carbon adopted in the activated carbon adsorption tower are as follows: the particle size is 8-30 meshes, the iodine adsorption value is 600-800 mg/g, the water content is less than or equal to 5 percent, and the strength is more than or equal to 90 percent; after passing through an ozone catalytic oxidation tower and an active carbon adsorption device, the COD concentration of the effluent is less than 100mg/L.
In the step (5), calcium hydroxide and sodium carbonate are added into the concentrated water softening clarification tank according to the hardness and alkalinity of the coking wastewater, so that the hardness of water is controlled below 100mg/L, and simultaneously, 50-100 mg/L of polymeric ferric sulfate and 2-5 mg/L of polyacrylamide are added, so that the concentration of silicon ions in the water is reduced to below 10mg/L, and the concentration of fluorine ions is reduced to below 10mg/L; filling quartz sand and anthracite into the multi-medium filter B, and operating the flow speed at 8-10 m/h; the running flow rate of the weak acid sodium type ion exchanger is less than 20m/h; the total hardness of effluent is less than 0.5mg/L.
In the step (6), the membrane flux of the low-pressure nanofiltration membrane in the low-pressure nanofiltration device is 15-20L/m 2 h, adopting a first-stage two-stage arrangement, wherein the water yield is 65-75%; the membrane flux of the high-pressure nanofiltration membrane in the high-pressure nanofiltration device is 10 to 15L/m 2 h, adopting one-stage arrangement, wherein the water yield is 50-60%; the indexes of the high-pressure nanofiltration concentrated water are as follows: the TDS concentration is 80000-120000 mg/L, the silicon ion concentration is less than 10mg/L, and the fluorine ion concentration is less than 10mg/L; the sodium sulfate evaporation, freezing, crystallization and recrystallization system comprises: a sodium sulfate falling film concentrator, a sodium sulfate evaporation crystallizer, a sodium sulfate freezing crystallizer and a sodium sulfate re-crystallizer; the content of sodium sulfate in the product is more than 98.5 percent.
In the step (7), the membrane flux of the secondary reverse osmosis membrane in the secondary reverse osmosis device is 10-15L/m 2 h, adopting a first-stage two-stage arrangement, wherein the water yield is 65-75%; the membrane flux of the concentration reverse osmosis membrane in the concentration reverse osmosis device is 10 to 15L/m 2 h, adopting a first-stage two-stage arrangement, wherein the water yield is 50-60%; the sodium chloride evaporative crystallization system comprises a sodium chloride evaporative crystallizer, and the content of sodium chloride in a product is more than 98.5%.
In the step (8), the membrane flux of the purification nanofiltration membrane in the purification nanofiltration device is 10 to 15L/m 2 h, adopting one-stage arrangement, wherein the water production indexes are as follows: TDS concentration is 70000-80000 mg/L, silicon ionThe concentration is less than 60mg/L, and the concentration of fluorine ions is less than 60mg/L.
A system for realizing zero discharge and resource utilization of coking wastewater comprises a softening clarification tank, a multi-media filter A, an ultrafiltration device, a primary reverse osmosis device, an ozone catalytic oxidation tower, an activated carbon adsorption tower, a concentrated water softening clarification tank, a multi-media filter B, a weak acid sodium type ion exchanger, a low-pressure nanofiltration device, a high-pressure nanofiltration device, a secondary reverse osmosis device, a concentration reverse osmosis device, a purification nanofiltration device, a sodium chloride evaporation crystallization system, a sodium sulfate evaporation and freezing crystallization system, a recrystallization system and a mixed salt evaporation crystallization device;
the softening clarification tank, the multi-media filter A, the ultrafiltration device and the primary reverse osmosis device are sequentially connected through a pipeline, a concentrated water outlet of the primary reverse osmosis device is sequentially connected with the ozone catalytic oxidation tower, the activated carbon adsorption tower, the concentrated water softening clarification tank, the multi-media filter B, the weak acid sodium type ion exchanger and the low-pressure nanofiltration device through pipelines, and a produced water outlet of the primary reverse osmosis device is connected with a produced water tank through a pipeline; a concentrated water outlet of the low-pressure nanofiltration device is sequentially connected with the high-pressure nanofiltration device and a sodium sulfate evaporation, freezing, crystallization and recrystallization system through pipelines; a water outlet of the low-pressure nanofiltration device is connected with a secondary reverse osmosis device through a pipeline, and a concentrated water outlet of the secondary reverse osmosis device is sequentially connected with a concentration reverse osmosis device and a purification nanofiltration device through pipelines; a concentrated water outlet of the purification nanofiltration device is connected with a sodium chloride evaporation crystallization system through a pipeline; a water outlet of the purification nanofiltration device is connected with a water inlet of the low-pressure nanofiltration device through a pipeline; a mother liquor outlet of the sodium sulfate evaporation and freezing crystallization and recrystallization system and a mother liquor outlet of the sodium chloride evaporation crystallization system are respectively connected with a mixed salt evaporation crystallization device through pipelines; the sodium sulfate evaporation, freezing crystallization and recrystallization system comprises a sodium sulfate falling film concentrator, a sodium sulfate evaporation crystallizer, a sodium sulfate freezing crystallizer and a sodium sulfate crystallizer; the sodium chloride evaporative crystallization system comprises a sodium chloride evaporative crystallizer.
The following examples are carried out on the premise of the technical scheme of the invention, and detailed embodiments and specific operation processes are given, but the scope of the invention is not limited to the following examples.
[ example 1 ] A method for producing a polycarbonate
In this example, the amount of water Q treated by a certain coking wastewater treatment plant was 520m 3 The coking wastewater subjected to biochemical treatment and advanced treatment has the following water quality indexes: the concentration of COD (chemical oxygen demand) is 60-80 mg/L, the concentration of TDS (dissolved total solids) is 3000-4000 mg/L, the concentration of chloride ions is 1000-1200 mg/L, the concentration of sulfate ions is 700-800 mg/L, the pH value is 7.0-7.5, the total hardness is 500-800 mg/L, the concentration of fluoride ions is 50-100 mg/L, and the concentration of silicon ions is 50-100 mg/L.
The pretreated coking wastewater firstly enters a softening clarification tank, calcium hydroxide and sodium carbonate are sequentially added according to the content of calcium and magnesium ions and the alkalinity of water, 60-80 mg/L of polymeric ferric sulfate and 3-5 mg/L of polyacrylamide are simultaneously added, the effluent meets the conditions that the total hardness is less than 100mg/L, the concentration of silicon ions is less than 10mg/L and the concentration of fluorine ions is less than 10mg/L.
The effluent of the softening clarification tank is filtered by a multi-media filter A filled with quartz sand and anthracite, and then enters an ultrafiltration device (external pressure type ultrafiltration membrane system), suspended matters and colloids in the water are removed, the turbidity of the effluent is less than 0.5NTU, and SDI (sludge density index) is less than 3.
The effluent of the ultrafiltration device is pressurized by a pump and then enters a first-level reverse osmosis device, according to the difference of the salt content of the inlet water, a reverse osmosis membrane system is set into 3 sections, the water production rate is maintained below 80%, the produced water enters a water production pool for recycling, the TDS concentration of the concentrated water is less than 20000mg/L, and the COD concentration is less than 300mg/L.
The first-stage reverse osmosis concentrated water enters an ozone catalytic oxidation tower, an active catalyst with aluminum oxide as a carrier is filled in the ozone catalytic oxidation tower, the hydraulic retention time is 1.5h, ozone is added according to the mass concentration ratio of ozone to COD =2:1, the effluent of the ozone catalytic oxidation reaction enters an active carbon adsorption tower, granular active carbon is filled in the active carbon adsorption tower, and the COD concentration of the effluent is 80-100 mg/L.
The effluent of the activated carbon adsorption tower sequentially enters a concentrated water softening clarification tank, 60-80 mg/L of calcium hydroxide, sodium carbonate, polymeric ferric sulfate and 3-5 mg/L of polyacrylamide are sequentially added according to the content of calcium and magnesium ions and the alkalinity of the water, the total hardness of the effluent is less than 100mg/L, the concentration of silicon ions is less than 10mg/L, and the concentration of fluorine ions is less than 15mg/L; the effluent of the softening clarification tank is filtered by a multi-media filter B filled with quartz sand and anthracite and then enters a weak acid-sodium type ion exchanger, and the effluent of the weak acid-sodium type ion exchanger satisfies that the total hardness is less than 0.5mg/L.
The effluent of the weak acid sodium type ion exchanger is pressurized by a pump and is sent into a low-pressure nanofiltration device, the water yield of the low-pressure nanofiltration device is maintained to be about 70 percent, the low-pressure nanofiltration concentrated water enters a high-pressure nanofiltration device, the concentration of sulfate ions in the water is further improved, the water yield of the high-pressure nanofiltration device is 50 to 60 percent, the COD concentration of the concentrated water is less than 400mg/L, the concentration of silicon ions is less than 10mg/L, and the concentration of fluorine ions is less than 15mg/L; and (4) allowing the high-pressure nanofiltration concentrated water to enter a sodium sulfate evaporation, freezing crystallization and recrystallization system.
The sodium sulfate evaporation, freezing crystallization and recrystallization system consists of a sodium sulfate falling film concentrator, a sodium sulfate evaporation crystallizer, a sodium sulfate freezing crystallizer and a sodium sulfate recrystallization device; the content of sodium sulfate in the product is more than 98.5 percent.
The high-pressure nanofiltration produced water and the low-pressure nanofiltration produced water are subjected to secondary reverse osmosis, the produced water of a secondary reverse osmosis device is maintained to be about 60-70 percent, the secondary reverse osmosis concentrated water enters a concentration reverse osmosis device, the water yield of the concentration reverse osmosis device is maintained to be 50-60 percent, the TDS concentration of the concentrated reverse osmosis effluent is 80000-100000 mg/L, and the secondary reverse osmosis produced water and the concentrated reverse osmosis produced water both enter a water production pool for recycling.
The concentrated reverse osmosis concentrated water enters a purification nanofiltration device, the produced water of the purification nanofiltration device flows back to the water inlet end of the low-pressure nanofiltration device, and the indexes of the purified nanofiltration concentrated water are as follows: TDS concentration is 70000-80000 mg/L, silicon ion concentration is less than 60mg/L, fluorine ion concentration is less than 60mg/L, and concentrated water enters a sodium chloride evaporation crystallization system.
The sodium chloride evaporative crystallization system comprises a sodium chloride evaporative crystallizer. The content of sodium chloride in the product is more than 98.5 percent.
[ example 2 ] A method for producing a polycarbonate
In this example, the amount Q of wastewater treated by coking wastewater of a certain coking plant was 70m 3 The coking wastewater subjected to biochemical treatment and advanced treatment has the following water quality indexes: COD (chemical oxygen demand) concentration is 80-100 mg/LThe concentration of TDS (total dissolved solids) is 4000-5000 mg/L, the concentration of chloride ions is 1200-1500 mg/L, the concentration of sulfate ions is 1000-1200 mg/L, the pH value is 7.0-7.5, the total hardness is 600-900 mg/L, the concentration of fluorine ions is 100-150 mg/L, and the concentration of silicon ions is 50-100 mg/L.
The pretreated coking wastewater firstly enters a softening clarification tank, calcium hydroxide and sodium carbonate are sequentially added according to the content of calcium and magnesium ions and the alkalinity of water, and 80-100 mg/L of polyferric sulfate and 3-5 mg/L of polyacrylamide are simultaneously added; the effluent water has total hardness less than 100mg/L, silicon ion concentration less than 10mg/L and fluorine ion concentration less than 10mg/L.
The effluent of the softening clarification tank is filtered by a multi-media filter A filled with quartz sand and anthracite, and then enters an ultrafiltration device (external pressure type ultrafiltration membrane system), suspended matters and colloids in the water are removed, the turbidity of the effluent is less than 0.5NTU, and the SDI concentration is less than 3.
The effluent of the ultrafiltration device is pressurized by a pump and then enters a first-stage reverse osmosis device, a reverse osmosis membrane system is set into 3 sections according to the difference of the salt content of the inlet water, the water yield is maintained below 80%, the produced water enters a water producing pool for reuse, the TDS concentration in the concentrated water is less than 25000mg/L, and the COD concentration is less than 350mg/L.
The first-stage reverse osmosis concentrated water enters an ozone catalytic oxidation tower, an active catalyst with aluminum oxide as a carrier is filled in the ozone catalytic oxidation tower, the hydraulic retention time is 2 hours, ozone is added according to the mass concentration ratio of ozone to COD =2:1, the effluent of the ozone catalytic oxidation reaction enters an active carbon adsorption tower, granular active carbon is filled in the active carbon adsorption tower, and the COD concentration of the effluent is 80-100 mg/L.
The effluent of the activated carbon adsorption tower enters a concentrated water softening clarification tank, calcium hydroxide and sodium carbonate are sequentially added according to the content of calcium and magnesium ions and the alkalinity of the water, 60-80 mg/L of polyferric sulfate and 3-5 mg/L of polyacrylamide are simultaneously added, the effluent meets the requirements that the total hardness is less than 100mg/L, the concentration of silicon ions is less than 10mg/L, and the concentration of fluorine ions is less than 15mg/L; the effluent of the concentrated water softening clarification tank is filtered by a multi-media filter B filled with quartz sand and anthracite and then enters a weak acid-sodium type ion exchanger, and the effluent of the weak acid-sodium type ion exchanger meets the requirement that the total hardness is less than 0.5mg/L.
The effluent of the weak acid sodium type ion exchanger is pressurized by a pump and is sent into a low-pressure nanofiltration device, the water yield of low-pressure nanofiltration is maintained to be about 70 percent, low-pressure nanofiltration concentrated water enters a high-pressure nanofiltration device, the concentration of sulfate ions in the water is further improved, the water yield of the high-pressure nanofiltration device is 50 to 60 percent, the COD concentration of the concentrated water is less than 400mg/L, the concentration of silicon ions is less than 10mg/L, and the concentration of fluorine ions is less than 15mg/L; and (4) allowing the high-pressure nanofiltration concentrated water to enter a sodium sulfate evaporation, freezing crystallization and recrystallization system.
The sodium sulfate evaporation, freezing crystallization and recrystallization system consists of a sodium sulfate falling film concentrator, a sodium sulfate evaporation crystallizer, a sodium sulfate freezing crystallizer and a sodium sulfate recrystallization crystallizer; the content of sodium sulfate in the product is more than 98.5 percent.
The low-pressure nanofiltration produced water and the high-pressure nanofiltration produced water are subjected to secondary reverse osmosis, the water yield of a secondary reverse osmosis device is maintained at about 60-70%, the secondary reverse osmosis concentrated water enters a concentration reverse osmosis device, the water yield of the concentration reverse osmosis device is maintained at 50-60%, the TDS concentration of the outlet water is 100000-120000 mg/L, and the secondary reverse osmosis produced water and the concentrated reverse osmosis produced water enter a water production pool for recycling.
The concentrated reverse osmosis concentrated water enters a purification nanofiltration device, the purification nanofiltration produced water flows back to the water inlet end of the low-pressure nanofiltration device, and the indexes of the purification nanofiltration concentrated water are as follows: TDS concentration is 70000-80000 mg/L, silicon ion concentration is less than 60mg/L, fluorine ion concentration is less than 60mg/L, and concentrated water enters a sodium chloride evaporation crystallization system.
The sodium chloride evaporative crystallization system comprises a sodium chloride evaporative crystallizer, and the content of sodium chloride in a product is more than 98.5%;
the above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered as the technical solutions and the inventive concepts of the present invention within the technical scope of the present invention.
Claims (10)
1. A process for realizing zero discharge and resource utilization of coking wastewater is characterized by comprising the following steps:
(1) The coking wastewater after advanced treatment firstly enters a softening clarification tank, calcium hydroxide, sodium carbonate, polymeric ferric sulfate and polyacrylamide are sequentially added into the softening clarification tank, calcium ions in water form calcium carbonate precipitates, magnesium ions form magnesium hydroxide precipitates, and silicon ions and fluorine ions in water are removed;
(2) The effluent of the softening and clarifying tank enters a multi-media filter A and an ultrafiltration device to remove suspended matters and colloid in the water, thereby meeting the water inlet requirement of reverse osmosis;
(3) After the ultrafiltration effluent is pressurized by a pump, the ultrafiltration effluent enters a first-stage reverse osmosis device, and the produced water enters a water producing pool for recycling;
(4) The first-stage reverse osmosis concentrated water sequentially enters an ozone catalytic oxidation tower and an active carbon adsorption tower to remove organic matters in the water;
(5) The water discharged from the active carbon adsorption tower enters a concentrated water softening clarification tank, calcium hydroxide, sodium carbonate, polymeric ferric sulfate and polyacrylamide are sequentially added into the concentrated water softening clarification tank, calcium ions in the water form calcium carbonate precipitates, magnesium ions form magnesium hydroxide precipitates, and silicon ions and fluorine ions in the water are removed; the effluent of the concentrated water softening clarification tank enters a multi-media filter B to remove suspended matters and colloids in water, and the effluent of the multi-media filter enters a weak acid sodium type ion exchanger to thoroughly remove calcium ions and magnesium ions in water;
(6) The outlet water of the weak acid sodium type ion exchanger is pressurized by a pump and then sent into a low-pressure nanofiltration device, nanofiltration concentrated water enters a high-pressure nanofiltration device, the concentration of sodium sulfate in the water is further improved, and the high-pressure nanofiltration concentrated water enters a sodium sulfate evaporation, freezing, crystallization and recrystallization system;
(7) The water produced by the low-pressure nanofiltration device and the water produced by the high-pressure nanofiltration device are further concentrated by a secondary reverse osmosis device and a concentration reverse osmosis device, the secondary reverse osmosis water and the concentration reverse osmosis water are recycled in a water production pool, and the concentrated reverse osmosis concentrated water enters a purification nanofiltration device;
(8) The purified nanofiltration produced water flows back to the water inlet end of the low-pressure nanofiltration device, and the purified nanofiltration concentrated water enters a sodium chloride evaporation crystallization system;
(9) Sodium sulfate evaporation and freezing crystallization, and the mother liquor of recrystallization and the mother liquor of sodium chloride evaporation crystallization enter a mixed salt evaporation crystallization device to produce mixed salt.
2. The process for realizing zero discharge and resource utilization of coking wastewater according to claim 1, characterized in that in the step (1), the coking wastewater subjected to advanced treatment has the following water quality indexes: COD concentration is 60-80 mg/L, TDS concentration is 3500-5000 mg/L, chloride ion concentration is 1000-2000 mg/L, and sulfate ion concentration is 800-2000 mg/L; adding calcium hydroxide and sodium carbonate into the softening clarification tank according to the hardness and alkalinity of the coking wastewater to control the hardness of water to be below 100 mg/L; meanwhile, 50-100 mg/L of polyferric sulfate and 2-5 mg/L of polyacrylamide are added, so that the concentration of silicon ions in water is reduced to be below 10mg/L, and the concentration of fluorine ions is reduced to be below 10mg/L.
3. The process for realizing zero discharge and resource utilization of coking wastewater according to claim 1, characterized in that in the step (2), quartz sand and anthracite are filled in the multi-media filter A, and the running flow rate is 8-10 m/h; the membrane flux of the ultrafiltration membrane in the ultrafiltration device is 35 to 45L/m 2 h; after being filtered by a multi-medium filter and an ultrafiltration device, the turbidity of the water is less than 0.5NTU, and the SDI is less than 3.
4. The process for realizing zero discharge and resource utilization of coking wastewater according to claim 1, characterized in that in the step (3), the membrane flux of the first-stage reverse osmosis membrane in the first-stage reverse osmosis device is 15-20L/m 2 h, adopting one-stage two-section or one-stage three-section arrangement, and controlling the recovery rate of the one-stage reverse osmosis at 75-80%.
5. The process for realizing zero discharge and resource utilization of coking wastewater according to claim 1, characterized in that in the step (4), a catalyst which takes activated aluminum dioxide as a carrier and contains iron ions and manganese ions is added into an ozone catalytic oxidation tower, the hydraulic retention time of the catalytic oxidation tower is 1-2 h, and the adding concentration ratio of ozone to COD in water is 1:1-3:1; the indexes of the granular activated carbon adopted in the activated carbon adsorption tower are as follows: the particle size is 8-30 meshes, the iodine adsorption value is 600-800 mg/g, the water content is less than or equal to 5 percent, and the strength is more than or equal to 90 percent; after passing through an ozone catalytic oxidation tower and an active carbon adsorption device, the COD concentration of the effluent is less than 100mg/L.
6. The process for realizing zero discharge and resource utilization of coking wastewater according to claim 1, wherein in the step (5), calcium hydroxide and sodium carbonate are added into a concentrated water softening and clarifying tank according to the hardness and alkalinity of the coking wastewater to control the hardness of water to be less than 100mg/L, and simultaneously, 50-100 mg/L of polyferric sulfate and 2-5 mg/L of polyacrylamide are added to reduce the concentration of silicon ions and fluoride ions in the water to be less than 10mg/L; filling quartz sand and anthracite into the multi-medium filter B, and operating the flow speed at 8-10 m/h; the running flow rate of the weak acid sodium type ion exchanger is less than 20m/h; the total hardness of effluent is less than 0.5mg/L.
7. The process for realizing zero discharge and resource utilization of coking wastewater according to claim 1, wherein in the step (6), the membrane flux of the low-pressure nanofiltration membrane in the low-pressure nanofiltration device is 15-20L/m 2 h, adopting a first-stage two-stage arrangement, wherein the water yield is 65-75%; the membrane flux of the high-pressure nanofiltration membrane in the high-pressure nanofiltration device is 10-15L/m 2 h, adopting one-stage arrangement, wherein the water yield is 50-60%; the indexes of the high-pressure nanofiltration concentrated water are as follows: TDS concentration is 80000-120000 mg/L, silicon ion concentration is less than 10mg/L, and fluorine ion concentration is less than 10mg/L; the sodium sulfate evaporation, freezing, crystallization and recrystallization system comprises: a sodium sulfate membrane-decreasing concentrator, a sodium sulfate evaporation crystallizer, a sodium sulfate freezing crystallizer and a sodium sulfate re-crystallizer; the content of sodium sulfate in the product is more than 98.5 percent.
8. The process for realizing zero discharge and resource utilization of coking wastewater according to claim 1, wherein in the step (7), the membrane flux of the secondary reverse osmosis membrane in the secondary reverse osmosis device is 10-15L/m 2 h, adopting a first-stage two-stage arrangement, wherein the water yield is 65-75%; the membrane flux of the concentrated reverse osmosis membrane in the concentrated reverse osmosis device is 10 to 15L/m 2 h, adopting a first-stage two-stage arrangement, wherein the water yield is 50-60%; the sodium chloride evaporative crystallization system comprises a sodium chloride evaporative crystallizer, and the content of sodium chloride in a product is more than 98.5%.
9. The process for realizing zero discharge and resource utilization of coking wastewater according to claim 1, wherein in the step (8), the membrane flux of the purification nanofiltration membrane in the purification nanofiltration device is 10 to 15L/m 2 h, adopting one-stage arrangement, wherein the water production indexes are as follows: TDS concentration is 70000-80000 mg/L, silicon ion concentration is less than 60mg/L, and fluorine ion concentration is less than 60mg/L.
10. The system for realizing zero discharge and resource utilization of coking wastewater in the process of claim 1 is characterized by comprising a softening clarification tank, a multi-media filter A, an ultrafiltration device, a primary reverse osmosis device, an ozone catalytic oxidation tower, an activated carbon adsorption tower, a concentrated water softening clarification tank, a multi-media filter B, a weak acid sodium type ion exchanger, a low-pressure nanofiltration device, a high-pressure nanofiltration device, a secondary reverse osmosis device, a concentration reverse osmosis device, a purification nanofiltration device, a sodium chloride evaporative crystallization system, a sodium sulfate evaporation and freezing crystallization and recrystallization system and a mixed salt evaporative crystallization device;
the softening clarification tank, the multi-media filter A, the ultrafiltration device and the primary reverse osmosis device are sequentially connected through pipelines, a concentrated water outlet of the primary reverse osmosis device is sequentially connected with the ozone catalytic oxidation tower, the activated carbon adsorption tower, the concentrated water softening clarification tank, the multi-media filter B, the weak acid sodium type ion exchanger and the low-pressure nanofiltration device through pipelines, and a produced water outlet of the primary reverse osmosis device is connected with the water production tank through a pipeline; a concentrated water outlet of the low-pressure nanofiltration device is sequentially connected with the high-pressure nanofiltration device and a sodium sulfate evaporation, freezing, crystallization and recrystallization system through pipelines; a water outlet of the low-pressure nanofiltration device is connected with a secondary reverse osmosis device through a pipeline, and a concentrated water outlet of the secondary reverse osmosis device is sequentially connected with a concentration reverse osmosis device and a purification nanofiltration device through pipelines; a concentrated water outlet of the purification nanofiltration device is connected with a sodium chloride evaporation crystallization system through a pipeline; the water outlet of the purification nanofiltration device is connected with the water inlet of the low-pressure nanofiltration device through a pipeline; a mother liquor outlet of the sodium sulfate evaporation and freezing crystallization and recrystallization system and a mother liquor outlet of the sodium chloride evaporation and crystallization system are respectively connected with a mixed salt evaporation and crystallization device through pipelines; the sodium sulfate evaporation, freezing crystallization and recrystallization system comprises a sodium sulfate falling film concentrator, a sodium sulfate evaporation crystallizer, a sodium sulfate freezing crystallizer and a sodium sulfate crystallizer; the sodium chloride evaporative crystallization system comprises a sodium chloride evaporative crystallizer.
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| CN116022965A (en) * | 2023-02-01 | 2023-04-28 | 深圳永清水务有限责任公司北京分公司 | Coking wastewater zero discharge treatment system and process |
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