CN111847742A - Industrial wastewater treatment system and application thereof - Google Patents

Industrial wastewater treatment system and application thereof Download PDF

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Publication number
CN111847742A
CN111847742A CN201910332919.3A CN201910332919A CN111847742A CN 111847742 A CN111847742 A CN 111847742A CN 201910332919 A CN201910332919 A CN 201910332919A CN 111847742 A CN111847742 A CN 111847742A
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China
Prior art keywords
water
reverse osmosis
nanofiltration
treatment
ultrafiltration
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CN201910332919.3A
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Chinese (zh)
Inventor
张新妙
焦旭阳
栾金义
彭海珠
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Sinopec Beijing Research Institute of Chemical Industry
China Petroleum and Chemical Corp
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Sinopec Beijing Research Institute of Chemical Industry
China Petroleum and Chemical Corp
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Priority to CN201910332919.3A priority Critical patent/CN111847742A/en
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    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00Multistage treatment of water, waste water, or sewage
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/02Treatment of water, waste water, or sewage by heating
    • C02F1/04Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • C02F1/048Purification of waste water by evaporation
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/44Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/441Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/44Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/442Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/44Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/444Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by ultrafiltration or microfiltration
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/18Nature of the water, waste water, sewage or sludge to be treated from the purification of gaseous effluents

Abstract

The present invention provides an industrial wastewater treatment system comprising: an ultrafiltration device; a nanofiltration device connected with the ultrafiltration device; the reverse osmosis device and the first evaporative crystallization device are respectively connected with the nanofiltration device; and the second evaporative crystallization device is connected with the reverse osmosis device. Through the cooperation use of ultrafiltration device, receive filter equipment, reverse osmosis unit, first evaporation crystallization device and second evaporation crystallization device, fully combined each respective advantage of device to solved the difficult problem of petrochemical enterprise catalytic cracking flue gas desulfurization waste water treatment, effectively realized water resource and salt resource utilization, still effectively utilized the low temperature heat source simultaneously.

Description

Industrial wastewater treatment system and application thereof
Technical Field
The invention relates to the field of industrial wastewater treatment, in particular to an industrial wastewater treatment system and application thereof.
Background
SO as the consumption of fossil fuels continues to increase in modern societyXAnd NOXAnd dust and other air pollutants are also generated in large quantities, and if the substances are discharged into the air in large quantities, serious air pollution can be caused. National and local government to SO XAnd NOXAnd the particulate matter emission standard is increasingly strict and the pollution discharge cost is gradually increased, and meanwhile, the emission standard of pollutants in the petrochemical industry (GB31571-2015) requires SO2Less than 100mg/m3,NOXLess than 150mg/m3The particle content is less than 20mg/m3. Under the circumstances, in order to meet strict environmental protection requirements and self development requirements of enterprises, currently, a flue gas desulfurization system is established in catalytic cracking units of almost all petrochemical enterprises.
Domestic petrochemical enterprises widely adopt an EDV wet washing technology developed by Belco corporation, the method can effectively remove oxysulfide in flue gas and simultaneously elute dust in the flue gas, but a large amount of desulfurization wastewater is generated along with the method, and the desulfurization wastewater mainly contains catalyst dust, sulfurous acid, sodium sulfate and other substances. The existing treatment methods mainly comprise three methods: mixing biochemical treatment, diluting, discharging, evaporating and crystallizing. Wherein, the culture difficulty of high-salt biochemical flora is higher, the biochemical treatment effect is influenced, and the quality of effluent fluctuates; for example, in some large petrochemical enterprises, desulfurization wastewater is usually mixed with other wastewater and then treated as general wastewater, so that although the problem of environmental protection is temporarily solved, the salt content of the reuse water of sewage reuse enterprises is gradually increased, and the salt balance is difficult to realize; the evaporation crystallization desalination treatment is adopted, the operation cost is high, the existing pretreatment process is insufficient, catalyst dust, organic matters and the like in the desulfurization wastewater are not completely removed, the recovered salts are difficult to reach the national industrial salt standard, and the recovered salts can only be used as solid waste or dangerous waste for disposal.
The patent CN201610592733.8 adopts a sodium-alkali method and an evaporation crystallization combined process to treat the desulfurization wastewater, and the process has the problems of high cost, incapability of long-period operation and the like. With the implementation of the discharge standard of pollutants in the petrochemical industry (GB31571-2015), certain regions have strict limits on the discharge of saline wastewater, for example, Beijing requires that the content of soluble solids in the wastewater is lower than 1600 mg/L. Therefore, the problem of discharge treatment of high-concentration salt-containing desulfurization wastewater generated by the EDV wet washing technology is a difficult problem of a technical use unit.
The method is an effective method by utilizing a membrane combination process matched with an evaporation technology, and a patent CN201510275955.2 discloses a desulfurization wastewater zero-discharge process, wherein the desulfurization wastewater is treated by adopting a membrane combination process of ultrafiltration, nanofiltration and reverse osmosis after two-stage softening, and then salt is separated and recovered by using ion exchange, freeze crystallization and evaporation processes, but the process has the problems of high operation pressure, high pretreatment requirement, large softening dosage, high energy consumption and complex system and equipment.
Disclosure of Invention
In view of the problems in the prior art, the present invention aims to provide an industrial wastewater treatment system, an application of the system in the field of industrial wastewater treatment, and a method for treating industrial wastewater by using the system, wherein the advantages of the ultrafiltration device, the nanofiltration device, the reverse osmosis device, the first evaporative crystallization device and the second evaporative crystallization device are fully combined by matching use of the ultrafiltration device, the nanofiltration device, the reverse osmosis device, the first evaporative crystallization device and the second evaporative crystallization device, so that the problem of difficulty in treating catalytic cracking flue gas desulfurization wastewater of petrochemical enterprises is solved, resource utilization of water resources and salts is effectively realized, and a low-temperature heat source is effectively utilized.
In one aspect, the present invention provides an industrial wastewater treatment system, comprising:
an ultrafiltration device;
a nanofiltration device connected with the ultrafiltration device;
the reverse osmosis device and the first evaporative crystallization device are respectively connected with the nanofiltration device;
and a second evaporative crystallization device connected with the reverse osmosis device,
the first evaporative crystallization device is a four-effect evaporative crystallization device, and the second evaporative crystallization device is a mechanical vapor recompression evaporator (MVR evaporative crystallizer for short).
The inventor of the application discovers through research that the ultrafiltration device can effectively remove catalyst dust and other suspended matters in industrial wastewater, and the ultrafiltration device also has the characteristics of simple equipment, high automation degree, easy operation and maintenance, strong environment adaptability, small occupied area and the like. The combination of the nanofiltration device and the reverse osmosis device can fully combine the advantages of the nanofiltration device and the reverse osmosis device, reduce the operation cost and realize the salt-type mass-separation crystallization in the wastewater. The first evaporative crystallization device can effectively utilize a low-temperature heat source, and the operation cost is reduced. The ultra-filtration device, the nano-filtration device, the reverse osmosis device, the first evaporative crystallization device and the second evaporative crystallization device are matched for use, and the respective advantages of the devices can be fully combined, so that the problem of difficulty in treating catalytic cracking flue gas desulfurization wastewater of petrochemical enterprises is solved, the resource utilization of water resources and salts is effectively realized, and meanwhile, a low-temperature heat source can be effectively utilized.
In some preferred embodiments of the present invention, the ultrafiltration apparatus employs an external pressure type hollow fiber membrane module.
In some preferred embodiments of the present invention, the nanofiltration device employs a roll-type nanofiltration membrane module.
In some preferred embodiments of the present invention, the reverse osmosis apparatus employs a wound reverse osmosis membrane module.
According to the invention, the four-effect evaporative crystallization device can adopt waste heat such as factory waste heat and the like as a low-temperature heat source.
According to the present invention, the MVR evaporative crystallizer may employ electric heating as a heat source.
The invention also provides application of the industrial wastewater treatment system in the field of industrial wastewater treatment, in particular to the field of catalytic cracking flue gas desulfurization wastewater treatment.
The inventor of the application finds in research that the industrial wastewater treatment system is particularly suitable for treating catalytic cracking flue gas desulfurization wastewater.
The invention provides a method for treating catalytic cracking flue gas desulfurization wastewater in a third aspect, which comprises the following steps:
enabling the catalytic cracking flue gas desulfurization wastewater to enter an ultrafiltration device, thereby carrying out ultrafiltration treatment on the catalytic cracking flue gas desulfurization wastewater to form ultrafiltration product water and an ultrafiltration concentrated phase;
the ultrafiltration water product enters a nanofiltration device, so that nanofiltration treatment is carried out on the ultrafiltration water product to form nanofiltration water product and nanofiltration concentrated water;
Enabling the nanofiltration concentrated water to enter a first evaporative crystallization device, thereby carrying out evaporative crystallization treatment on the nanofiltration concentrated water to form sodium sulfate solid and first evaporative crystallization water;
the nanofiltration produced water enters a reverse osmosis device, so that reverse osmosis treatment is carried out on the nanofiltration produced water to form reverse osmosis produced water reverse osmosis concentrated water; and
and (3) enabling the reverse osmosis concentrated water to enter a second evaporation and crystallization device, thereby carrying out evaporation and crystallization treatment on the reverse osmosis concentrated water to form sodium chloride solid and second evaporation and crystallization water production. According to the invention, the ultrafiltration concentrated phase is treated by centralized transportation after sludge dehydration and solidification.
In some preferred embodiments of the invention, the pH of the catalytic cracking flue gas desulfurization wastewater is 7.5-8.5, the conductivity is 10000-15000 mu S/cm, the total nitrogen is 20-50mg/L, the suspended matter concentration is 100-200 mg/L, the oil content is 0-2 mg/L, and Cl is-The concentration is 10-50 mg/L, SO4 2-The concentration is 6000-7000 Mg/L, Mg2+Ca at a concentration of 1-5 mg/L2+The concentration is 4-10 mg/L, Na+The concentration is 3000-4000 mg/L, and the concentration of dissolved silicon is 3-8 mg/L. The COD of the catalytic cracking flue gas desulfurization wastewater can be 20-50 mg/L.
In some preferred embodiments of the invention, the first evaporative crystallization water production, the second evaporative crystallization water production and the reverse osmosis water production all satisfy the requirements of conductivity < 1200 μ S/cm, COD < 60mg/L, Cl -The concentration is less than 200mg/L, and the oil content is less than 0.5 mg/L.
According to the invention, the conductivity is less than 1200 mu S/cm, the COD is less than 60mg/L, and the Cl is-The concentration is less than 200mg/L, and the oil content is less than 0.5mg/L, which is the recycling requirement of recycled circulating water. First evaporation crystallization to produce waterThe secondary evaporation crystallization water production and the reverse osmosis water production meet the recycling requirement and can be recycled for supplementing water by circulating water.
In some preferred embodiments of the present invention, the pressure of the ultrafiltration treatment is 0.08 to 0.12 MPa.
According to the present invention, on the one hand, when the pressure of ultrafiltration treatment is less than 0.08MPa, the ultrafiltration membrane flux is too small, the number of required components increases, and the cost increases; on the other hand, when the pressure of the ultrafiltration treatment is more than 0.12MPa, the rupture of the ultrafiltration membrane filaments is caused, which affects the service life. Therefore, in order to obtain high membrane flux and separation efficiency, the pressure of ultrafiltration treatment is limited to 0.08-0.12 MPa.
In some preferred embodiments of the present invention, the pH of the influent water of the nanofiltration device is 7.5 to 8.5; the pressure of nanofiltration treatment is 2.0-3.0 MPa, and the membrane flux is 15-25L/m2·h。
According to the present invention, in one aspect, when the pressure of the nanofiltration treatment is less than 2.0MPa, the membrane flux and the separation efficiency of salts are low; on the other hand, when the pressure of the nanofiltration treatment is more than 3.0MPa, the membrane flux and the salt separation efficiency are not obviously improved, but the membrane is damaged, and the operation cost of the device is increased. Therefore, in order to obtain economic and reasonable salt separation efficiency, the pressure of nanofiltration treatment is limited to 2.0-3.0 MPa.
In some preferred embodiments of the present invention, the feed water of the reverse osmosis apparatus has a pH of 7.0 to 8.0; the pressure of reverse osmosis treatment is 2.0-3.0 MPa, and the membrane flux is 16-26L/m2·h。
According to the present invention, in one aspect, when the pressure of the reverse osmosis treatment is less than 2.0MPa, the membrane flux is low and the operation time is long; on the other hand, when the pressure of the reverse osmosis process is more than 3.0MPa, damage may be caused to the reverse osmosis module and the operation cost may be increased. Therefore, in order to obtain high membrane flux and ensure the recovery rate of the system, the pressure of reverse osmosis treatment is limited to 2.0-3.0 MPa.
In some preferred embodiments of the present invention, the conditions under which the nanofiltration concentrated water is subjected to evaporative crystallization treatment include: the pressure is 0.4-1 Mpa, the feeding temperature is 40-60 ℃, and the evaporation temperature is 50-70 ℃; and/or the conditions for carrying out the evaporative crystallization treatment on the reverse osmosis concentrated water comprise: the feed preheating temperature of the MVR evaporation crystallizer is 50-70 ℃, the evaporation temperature of the forced circulation crystallizer is 70-90 ℃, and the material flow rate is 2-3 m/s.
According to the invention, the term "COD" refers to chemical oxygen demand.
The industrial wastewater treatment system provided by the invention is used for treating catalytic cracking flue gas desulfurization wastewater, on the basis of effectively treating the catalytic cracking flue gas desulfurization wastewater, the water resource recovery in the wastewater is realized, the problems of high suspended matter content and high energy consumption of the catalytic cracking flue gas desulfurization wastewater in the treatment process are solved, the quality-divided crystallization treatment of the catalytic cracking flue gas desulfurization wastewater is realized, the system produced water formed after the treatment by the method can be directly recycled for water supplement of circulating water, the advanced treatment and recycling of the wastewater are realized, and simultaneously, the high-purity sodium sulfate and sodium chloride salt obtained after the treatment by the method can also be recycled as renewable resources.
Drawings
FIG. 1 is a process flow diagram of the method for treating catalytic cracking flue gas desulfurization wastewater of the present invention.
Detailed Description
The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited to the following description.
In the embodiment described below, it is preferred that,
the model of the external pressure type hollow fiber membrane component used in the ultrafiltration device is SFP-2880;
the model of the spiral-wound nanofiltration membrane component used in the nanofiltration device is Dow NF-400;
the model of the roll type reverse osmosis membrane module used in the reverse osmosis device is BW30 FR;
the model of the four-effect evaporation crystallization device is a forced circulation four-effect evaporator;
the MVR evaporative crystallizer is the model MVR evaporative crystallizer (OSLO).
Example 1
In the present embodiment, it isThe main water quality characteristics of the catalytic cracking flue gas desulfurization wastewater are as follows: pH of 7.5, inlet water conductivity of 10000. mu.S/cm, COD of 25mg/L, total nitrogen of 20mg/L, suspended matter of 100mg/L, oil content of 1mg/L, and Cl-Concentration 20mg/L, SO4 2-Concentration 6000Mg/L, Mg2+Concentration 2mg/L, Ca2+Concentration 5mg/L, Na+The concentration is 3000mg/L, and the concentration of dissolved silicon is 5 mg/L.
In this embodiment, the processing system used is:
an ultrafiltration device adopting an external pressure type hollow fiber membrane component;
A nanofiltration device which is connected with the ultrafiltration device and adopts a roll-type nanofiltration membrane component;
a reverse osmosis device and a four-effect evaporation crystallization device of the roll type reverse osmosis membrane component are respectively connected with the nanofiltration device; and
and the MVR evaporation crystallizer is connected with the reverse osmosis device.
The treatment system is used for treating the catalytic cracking flue gas desulfurization wastewater, and the treatment steps are as follows:
the catalytic cracking flue gas desulfurization wastewater enters an ultrafiltration device, and is subjected to ultrafiltration treatment under the pressure of 0.08MPa, so that solid suspended matters and macromolecular substances in the wastewater are removed, and ultrafiltration product water and an ultrafiltration concentrated phase are finally formed, wherein the turbidity of the ultrafiltration product water is less than 0.1NTU, and the ultrafiltration concentrated phase is subjected to centralized transportation treatment after sludge dehydration;
the ultrafiltration water (pH 7.5) enters a nanofiltration device and is at a pressure of 2MPa and a volume of 15-18L/m2H, carrying out nanofiltration treatment on the ultrafiltration water product under the membrane flux to form nanofiltration water product and nanofiltration concentrated water, wherein the COD of the nanofiltration water product is 24__ mg/L, the conductivity is 600 mu S/cm, and Na is added+Concentration 150mg/L, Cl-Concentration of 15mg/L, SO4 2-The concentration is 18 mg/L; the COD of the nanofiltration concentrated water is 27mg/L, the total nitrogen is 22mg/L, the conductivity is 27mS/cm, and Na is added +Concentration is 10000mg/L, Cl-Concentration of 5mg/L, SO4 2-Ca at a concentration of 25000mg/L2+Concentration 7Mg/L, Mg2+The concentration is 10 mg/L;
the nanofiltration concentrated water enters a four-effect evaporation crystallization device, the pressure is 0.4Mpa, the feeding temperature is 40 ℃, and the evaporation temperature is 50 ℃, so that the nanofiltration concentrated water is subjected to evaporation crystallization treatment to form sodium sulfate and first evaporation crystallization product water, wherein the recovery rate of the sodium sulfate is 95%, and the first evaporation crystallization product water meets the recycling requirement of recycled circulating water replenishing;
the nanofiltration produced water (pH is 7.0) enters a reverse osmosis device and enters a reverse osmosis device at the pressure of 2MPa and the concentration of 16-22L/m2Carrying out reverse osmosis treatment on the ultrafiltration produced water under the membrane flux of h to form reverse osmosis produced water and reverse osmosis concentrated water, wherein the conductivity of the reverse osmosis concentrated water is 9000-10000 mu S/cm, and the reverse osmosis produced water meets the water supplementing and recycling requirements of recycled circulating water; and
feeding reverse osmosis concentrated water into an MVR evaporation crystallizer, preheating at 50 ℃, evaporating at 70 ℃ in a forced circulation crystallizer, and feeding at a material flow rate of 2m/s, so as to carry out evaporative crystallization treatment on the reverse osmosis concentrated water to form sodium chloride and second evaporative crystallization product water, wherein the recovery rate of the sodium chloride is 90%, and the reverse osmosis product water meets the water supplementing and recycling requirements of recycled circulating water;
And using the first evaporative crystallization produced water, the second evaporative crystallization produced water and the reverse osmosis produced water for supplementing circulating water.
Example 2
In this embodiment, the main water quality characteristics of the treated catalytic cracking flue gas desulfurization wastewater are as follows: pH of 8.0, inlet water conductivity of 13000 mu S/cm, COD of 35mg/L, total nitrogen of 30mg/L, suspended matter of 150mg/L, oil content of 1.5mg/L, Cl-Concentration 30mg/L, SO4 2-6500Mg/L, Mg2+Concentration 3mg/L, Ca2+The concentration is 7mg/L, Na+The concentration is 3500mg/L, and the concentration of dissolved silicon is 6 mg/L.
In this embodiment, the same processing system as that of embodiment 1 is used.
The treatment system is used for treating the catalytic cracking flue gas desulfurization wastewater, and the treatment steps are as follows:
the method comprises the following steps of enabling catalytic cracking flue gas desulfurization wastewater to enter an ultrafiltration device, and carrying out ultrafiltration treatment on the catalytic cracking flue gas desulfurization wastewater under the pressure of 0.1MPa, so as to remove solid suspended matters and macromolecular substances in the wastewater, and finally forming ultrafiltration product water and an ultrafiltration concentrated phase, wherein the turbidity of the ultrafiltration product water is less than 0.1NTU, and the ultrafiltration concentrated phase is subjected to centralized transportation treatment after sludge dehydration;
the ultrafiltration water (pH is 8.0) enters a nanofiltration device and is filtered at the pressure of 2.5MPa and the pressure of 18-22L/m2H, performing nanofiltration treatment on the ultrafiltration produced water under the membrane flux to form nanofiltration produced water and nanofiltration concentrated water, wherein the COD of the nanofiltration produced water is 33mg/L, the conductivity is 700 mu S/cm, and Na is added +Concentration 180mg/L, Cl-Concentration of 25mg/L, SO4 2-The concentration is 18 mg/L; the COD of the nanofiltration concentrated water is 37mg/L, the total nitrogen is 30mg/L, the conductivity is 35mS/cm, and Na is added+Concentration 12000mg/L, Cl-Concentration of 10mg/L, SO4 2-Concentration of 28000mg/L, Ca2+Concentration 6Mg/L, Mg2+The concentration is 15 mg/L;
the nanofiltration concentrated water enters a four-effect evaporation crystallization device, the pressure is 0.7Mpa, the feeding temperature is 50 ℃, and the evaporation temperature is 60 ℃, so that the nanofiltration concentrated water is subjected to evaporation crystallization treatment to form sodium sulfate and first evaporation crystallization product water, wherein the recovery rate of the sodium sulfate is 96%, and the first evaporation crystallization product water meets the recycling requirement of recycled circulating water replenishing;
the nanofiltration produced water (pH is 7.5) enters a reverse osmosis device, and the pressure is 2.5MPa and the concentration is 17-25L/m2Carrying out reverse osmosis treatment on the ultrafiltration produced water under the membrane flux of h to form reverse osmosis produced water and reverse osmosis concentrated water, wherein the conductivity of the reverse osmosis concentrated water is 10000-12000 mu S/cm, and the reverse osmosis produced water meets the water supplementing and recycling requirements of recycled circulating water; and
enabling reverse osmosis concentrated water to enter an MVR evaporation crystallizer, wherein the feed preheating temperature is 60 ℃, the evaporation temperature of a strong forced circulation crystallizer is 80 ℃, and the material flow rate is 2.5m/s, so that the reverse osmosis concentrated water is subjected to evaporation crystallization treatment to form sodium chloride and second evaporation crystallization product water, wherein the recovery rate of the sodium chloride is 92%, and the reverse osmosis product water meets the recycling requirement of recycled circulating water replenishing water;
And using the first evaporative crystallization produced water, the second evaporative crystallization produced water and the reverse osmosis produced water for supplementing circulating water.
Example 3
In the bookIn the embodiment, the main water quality characteristics of the treated catalytic cracking flue gas desulfurization wastewater are as follows: pH was 8.5, conductivity of influent was 15000. mu.S/cm, COD was 45mg/L, total nitrogen was 20mg/L, suspended matter was 200mg/L, oil content was 2.0mg/L, Cl-Concentration 50mg/L, SO4 2-At a concentration of 7000Mg/L, Mg2+Concentration 5mg/L, Ca2+Concentration 10mg/L, Na+The concentration is 4000mg/L, and the concentration of dissolved silicon is 7 mg/L.
In this embodiment, the same processing system as that of embodiment 1 is used.
The treatment system is used for treating the catalytic cracking flue gas desulfurization wastewater, and the treatment steps are as follows:
the catalytic cracking flue gas desulfurization wastewater enters an ultrafiltration device, and is subjected to ultrafiltration treatment under the pressure of 0.12MPa, so that solid suspended matters and macromolecular substances in the wastewater are removed, and ultrafiltration product water and an ultrafiltration concentrated phase are finally formed, wherein the turbidity of the ultrafiltration product water is less than 0.1NTU, and the ultrafiltration concentrated phase is subjected to centralized transportation treatment after sludge dehydration;
the ultrafiltration water (pH 8.5) enters a nanofiltration device at the pressure of 3.0MPa and 20-25L/m2H, performing nanofiltration treatment on the ultrafiltration produced water under the membrane flux to form nanofiltration produced water and nanofiltration concentrated water, wherein the COD of the nanofiltration produced water is 45mg/L, the conductivity is 800 muS/cm, and Na is added +Concentration 200mg/L, Cl-Concentration of 40mg/L, SO4 2-The concentration is 20 mg/L; the COD of the nanofiltration concentrated water is 47mg/L, the total nitrogen is 19mg/L, the conductivity is 40mS/cm, and Na is added+Concentration 14000mg/L, Cl-Concentration of 15mg/L, SO4 2-The concentration is 30000mg/L, Ca2+Concentration 8Mg/L, Mg2+The concentration is 20 mg/L;
the nanofiltration concentrated water enters a four-effect evaporation crystallization device, the pressure is 1Mpa, the feeding temperature is 60 ℃, and the evaporation temperature is 70 ℃, so that the nanofiltration concentrated water is subjected to evaporation crystallization treatment to form sodium sulfate and first evaporation crystallization product water, wherein the recovery rate of the sodium sulfate is 98%, and the first evaporation crystallization product water meets the water replenishing and recycling requirements of recycled circulating water;
the nanofiltration produced water (pH is 8.0) enters a reverse osmosis device and is subjected to reverse osmosis under the pressure of 3MPa and the pressure of 18-26L/m2Carrying out reverse osmosis treatment on the ultrafiltration produced water under the membrane flux of h to form reverse osmosis produced water and reverse osmosis concentrated water, wherein the conductivity of the reverse osmosis concentrated water is 11000-13000 mu S/cm, and the reverse osmosis produced water meets the water supplementing and recycling requirements of recycled circulating water; and
enabling reverse osmosis concentrated water to enter an MVR evaporation crystallizer, wherein the feed preheating temperature is 70 ℃, the evaporation temperature of a strong forced circulation crystallizer is 90 ℃, and the material flow rate is 3m/s, so that the reverse osmosis concentrated water is subjected to evaporation crystallization treatment to form sodium chloride and second evaporation crystallization product water, wherein the recovery rate of the sodium chloride is 95%, and the reverse osmosis product water meets the recycling requirement of recycled circulating water replenishing;
And using the first evaporative crystallization produced water, the second evaporative crystallization produced water and the reverse osmosis produced water for supplementing circulating water.
Example 4
In this embodiment, the main water quality characteristics of the treated catalytic cracking flue gas desulfurization wastewater are as follows: pH of 7.5, inlet water conductivity of 10000. mu.S/cm, COD of 25mg/L, total nitrogen of 20mg/L, suspended matter of 100mg/L, oil content of 1mg/L, and Cl-Concentration 20mg/L, SO4 2-Concentration 6000Mg/L, Mg2+Concentration 2mg/L, Ca2+Concentration 5mg/L, Na+The concentration is 3000mg/L, and the concentration of dissolved silicon is 5 mg/L.
In this embodiment, the processing system used is:
an ultrafiltration device adopting an external pressure type hollow fiber membrane component;
a reverse osmosis device of the roll type reverse osmosis membrane component connected with the ultrafiltration device;
and the MVR evaporation crystallizer is connected with the reverse osmosis device.
The catalytic cracking flue gas desulfurization wastewater enters an ultrafiltration device, and is subjected to ultrafiltration treatment under the pressure of 0.08MPa, so that solid suspended matters and macromolecular substances in the wastewater are removed, and ultrafiltration product water and an ultrafiltration concentrated phase are finally formed, wherein the turbidity of the ultrafiltration product water is less than 0.1NTU, and the ultrafiltration concentrated phase is subjected to centralized transportation treatment after sludge dehydration;
the ultrafiltration water (pH 7.5) enters a reverse osmosis device and is subjected to ultrafiltration at a pressure of 2MPa and a concentration of 16-22L/m 2H, performing reverse osmosis treatment on the ultrafiltration product water under the membrane flux to form reverse osmosis product water and reverse osmosis concentrated water, wherein the conductivity of the reverse osmosis product water is 600 mu S/cm, Na+Concentration of 100mg/L, Cl-Concentration of 10mg/L, SO4 2-The concentration is 15 mg/L; the conductivity of the reverse osmosis concentrated water is 27mS/cm, Na+Concentration is 10000mg/L, Cl-Concentration of 20mg/L, SO4 2-The concentration was 25000 mg/L.
The reverse osmosis produced water meets the water replenishing and recycling requirements of recycled circulating water; and
feeding reverse osmosis concentrated water into an MVR evaporation crystallizer, wherein the preheating temperature of the feed is 50 ℃, the evaporation temperature of a strong forced circulation crystallizer is 70 ℃, and the material flow rate is 2m/s, so that the reverse osmosis concentrated water is subjected to evaporative crystallization treatment to form sodium chloride and second evaporative crystallization product water, wherein the reverse osmosis product water meets the water supplementing and recycling requirements of recycled circulating water;
and using the second evaporative crystallization produced water and the reverse osmosis produced water for supplementing water by circulating water.
After being treated by ultrafiltration and reverse osmosis technologies, the catalytic cracking flue gas desulfurization wastewater enters an MVR evaporative crystallization process to obtain mixed salt of sodium chloride and sodium sulfate, so that the salt cannot be recycled.
Example 5
The catalytic cracking flue gas desulfurization wastewater treated in the embodiment and the treatment system adopted in the embodiment are the same as those in embodiment 1, and the difference is only that the pressure of 1.5MPa and the pressure of 8-12L/m are adopted 2H nanofiltration of the ultrafiltrated produced water at membrane flux instead of 15-18L/m at 2MPa in example 12H nanofiltration treatment of the ultrafiltration product water at membrane flux ". As a result, among them, the water produced by nanofiltration had COD of 23mg/L, conductivity of 1000. mu.S/cm and Na+Concentration 150mg/L, Cl-Concentration of 10mg/L, SO4 2-The concentration is 15 mg/L; the COD of the nanofiltration concentrated water is 28mg/L, the total nitrogen is 20mg/L, the conductivity is 25mS/cm, and Na is added+Concentration 9000mg/L, Cl-Concentration of 10mg/L, SO4 2-The concentration is 20000mg/L, Ca2+Concentration 8Mg/L, Mg2 +The concentration is 9 mg/L;
the recovery rate of the obtained sodium sulfate is 90%, the recovery rate of the sodium chloride is 75%, the time of the nanofiltration separation process is increased, and the separation efficiency is reduced, so that the purity of the subsequent sodium sulfate and sodium chloride after evaporation crystallization is reduced.
Example 6
The catalytic cracking flue gas desulfurization wastewater treated in the embodiment and the treatment system adopted in the embodiment are the same as those in embodiment 1, and the difference is only that the pressure of 3.5MPa and the pressure of 30-37L/m are adopted2H nanofiltration of the ultrafiltrated produced water at membrane flux instead of 15-18L/m at 2MPa in example 12H nanofiltration treatment of the ultrafiltration product water at membrane flux ". As a result, it was found that,
Wherein the COD of the nanofiltration water is 21mg/L, the conductivity is 500 mu S/cm, and Na is added+Concentration 150mg/L, Cl-Concentration of 20mg/L, SO4 2-The concentration is 10mg/L, the COD of the nanofiltration concentrated water is 30mg/L, the total nitrogen is 18mg/L, the conductivity is 30mS/cm, and Na is added+Concentration 1000mg/L, Cl-Concentration of 5mg/L, SO4 2-The concentration is 27000mg/L, Ca2+Concentration 7Mg/L, Mg2+The concentration is 15 mg/L;
the recovery rate of the obtained sodium sulfate is 95 percent, the recovery rate of the sodium chloride is 85 percent, the membrane flux in the nanofiltration separation process is increased, the separation time is shortened, but the purity of the subsequent sodium chloride and sodium sulfate obtained by evaporation crystallization is not increased too much, and after the pressure is increased, the requirement on equipment is higher, the cost is increased, and the economic benefit is reduced.
It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.

Claims (10)

1. An industrial wastewater treatment system comprising:
an ultrafiltration device;
a nanofiltration device connected with the ultrafiltration device;
the reverse osmosis device and the first evaporative crystallization device are respectively connected with the nanofiltration device; and
the second evaporative crystallization device is connected with the reverse osmosis device;
the first evaporative crystallization device is a four-effect evaporative crystallization device, and the second evaporative crystallization device is a mechanical vapor recompression evaporator.
2. The industrial wastewater treatment system according to claim 1, wherein the ultrafiltration device employs a plate-type, tubular-type or hollow fiber-type membrane module, preferably an external pressure-type hollow fiber membrane module;
and/or the nanofiltration device adopts a plate-type or roll-type nanofiltration membrane component, preferably a roll-type nanofiltration membrane component;
and/or the reverse osmosis device adopts a roll-type or flat-plate type reverse osmosis membrane module, preferably a roll-type reverse osmosis membrane module.
3. Use of an industrial wastewater treatment system according to claim 1 or 2 in the field of industrial wastewater treatment, in particular in the field of catalytic cracking flue gas desulfurization wastewater treatment.
4. A method for treating catalytic cracking flue gas desulfurization wastewater comprises the following steps:
Enabling the catalytic cracking flue gas desulfurization wastewater to enter an ultrafiltration device, thereby carrying out ultrafiltration treatment on the catalytic cracking flue gas desulfurization wastewater to form ultrafiltration product water and an ultrafiltration concentrated phase;
the ultrafiltration water product enters a nanofiltration device, so that nanofiltration treatment is carried out on the ultrafiltration water product to form nanofiltration water product and nanofiltration concentrated water;
enabling the nanofiltration concentrated water to enter a first evaporative crystallization device, thereby carrying out evaporative crystallization treatment on the nanofiltration concentrated water to form sodium sulfate solid and first evaporative crystallization water;
the nanofiltration produced water enters a reverse osmosis device, so that reverse osmosis treatment is carried out on the nanofiltration produced water to form reverse osmosis produced water and reverse osmosis concentrated water; and
and (3) enabling the reverse osmosis concentrated water to enter a second evaporation and crystallization device, thereby carrying out evaporation and crystallization treatment on the reverse osmosis concentrated water to form sodium chloride solid and second evaporation and crystallization water production.
5. The method according to claim 4, wherein the pH of the catalytic cracking flue gas desulfurization wastewater is 7.5-8.5, the conductivity is 10000-15000 μ S/cm, the total nitrogen concentration is 20-50 mg/L, the suspended matter concentration is 100-200 mg/L, the oil content is 0-2 mg/L, and Cl is contained in the wastewater-The concentration is 10-50 mg/L, SO4 2-The concentration is 6000-7000 Mg/L, Mg 2+Ca at a concentration of 1-5 mg/L2+The concentration is 4-10 mg/L, Na+The concentration is 3000-4000 mg/L, and the concentration of dissolved silicon is 3-8 mg/L.
6. The method of claim 4 or 5, wherein the first evaporative crystallization water production, the second evaporative crystallization water production, and the reverse osmosis water production all satisfy the conditions of conductivity < 1200 μ S/cm, COD < 60mg/L, Cl-The concentration is less than 200mg/L, and the oil content is less than 0.5 mg/L.
7. The method according to any one of claims 4 to 6, wherein the pressure of the ultrafiltration treatment is 0.08 to 0.12 MPa.
8. The method according to any one of claims 4 to 7, wherein the pH of the feed water of the nanofiltration device is 7.5 to 8.5; the pressure of nanofiltration treatment is 2.0-3.0 MPa, and the membrane flux is 15-25L/m2·h。
9. The method according to any one of claims 4 to 8, wherein the feed water to the reverse osmosis apparatus has a pH of 7.0 to 8.0; the pressure of reverse osmosis treatment is 2.0-3.0 MPa, and the membrane flux is 16-26L/m2·h。
10. The process of any one of claims 4-9, wherein the conditions under which the nanofiltration concentrated water is subjected to evaporative crystallization treatment comprise: the pressure is 0.4-1 Mpa, the feeding temperature is 40-60 ℃, and the evaporation temperature is 50-70 ℃; and/or the conditions for carrying out the evaporative crystallization treatment on the reverse osmosis concentrated water comprise: the feed preheating temperature of the MVR evaporation crystallizer is 50-70 ℃, the evaporation temperature of the forced circulation crystallizer is 70-90 ℃, and the material flow rate is 2-3 m/s.
CN201910332919.3A 2019-04-24 2019-04-24 Industrial wastewater treatment system and application thereof Pending CN111847742A (en)

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