CN116253465A - Desulfurization wastewater treatment system and desulfurization wastewater treatment method - Google Patents

Desulfurization wastewater treatment system and desulfurization wastewater treatment method Download PDF

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Publication number
CN116253465A
CN116253465A CN202310177944.5A CN202310177944A CN116253465A CN 116253465 A CN116253465 A CN 116253465A CN 202310177944 A CN202310177944 A CN 202310177944A CN 116253465 A CN116253465 A CN 116253465A
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water
tank
wastewater
desulfurization
reverse osmosis
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王元华
王涛
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Lvliang Jianlong Industrial Co Ltd
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Lvliang Jianlong Industrial Co Ltd
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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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/18—Absorbing units; Liquid distributors therefor
    • B01D53/185—Liquid distributors
    • 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
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—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
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F2001/007—Processes including a sedimentation step
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/18—Nature of the water, waste water, sewage or sludge to be treated from the purification of gaseous effluents
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/14—Maintenance of water treatment installations
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/16—Regeneration of sorbents, filters
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124—Water desalination
    • Y02A20/131—Reverse-osmosis

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  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

The invention provides a desulfurization wastewater treatment system and a desulfurization wastewater treatment method, wherein the desulfurization wastewater treatment system comprises a wastewater regulating tank, a wastewater dosing reaction tank, a clarification concentration tank, a clean water tank, a sand filtration system, an ultrafiltration system, a reverse osmosis water production tank and a backwashing system, wherein a medicament bin is arranged on the wastewater dosing reaction tank, a hydrochloric acid bin is arranged on the clean water tank, the ultrafiltration system comprises an ultrafiltration membrane, and the reverse osmosis system comprises a plurality of groups of reverse osmosis membranes. According to the desulfurization wastewater treatment system and the desulfurization wastewater treatment method provided by the embodiment of the invention, equipment blockage can be reduced, satisfactory desulfurization wastewater treatment efficiency is achieved, the purified produced water of the desulfurization wastewater can be recycled and used as the process water of the desulfurization system, the process flow is simple, the system is stable and reliable, and the investment and operation cost is low.

Description

Desulfurization wastewater treatment system and desulfurization wastewater treatment method
Technical Field
The invention relates to the technical field of desulfurization wastewater treatment, in particular to a desulfurization wastewater treatment system and a desulfurization wastewater treatment method.
Background
In the treatment of high sulfur sintering flue gas in the industrial field, lime/limestone-gypsum wet flue gas desulfurization is mostly adopted. In the traditional wet flue gas desulfurization process, a desulfurization wastewater treatment system is closely related to a wet desulfurization dehydration system, the normal operation of the dehydration system can be ensured only by normal discharge of desulfurization wastewater, and the normal operation of the dehydration system is the guarantee of gypsum quality of wet desulfurization products, so that a certain amount of desulfurization wastewater needs to be discharged periodically by a desulfurization tower. Meanwhile, in order to ensure the quality of the by-product desulfurized gypsum of the wet desulfurization system, the concentration of chloride ions needs to be controlled in a slurry circulation system. In addition, as the operating load of the wet desulfurization system fluctuates, the amount of wastewater treatment produced by the desulfurization wastewater system also varies.
The operation of the desulfurization wastewater treatment system in the wet flue gas desulfurization process can be adjusted according to the concentration of chloride ions in the desulfurization tower, so that the desulfurization wastewater treatment system is frequently operated discontinuously, and the problem of blockage of desulfurization wastewater treatment equipment is easily caused.
The traditional desulfurization wastewater treatment mainly adopts a chemical precipitation method, and heavy metal pollutants in the desulfurization wastewater are removed through technologies such as oxidation, neutralization, precipitation and the like. The related conventional equipment mainly comprises equipment such as a wastewater tank, a sludge filter press, a stirrer, a dosing pump and the like. The chemical precipitation method mainly uses hydrochloric acid, ferric chloride sulfate, lime powder, PAM, TMT15, etc. The cost of the treatment mode is high by using various chemical agents, and the problem that the concentration of chloride ions in the treated desulfurization wastewater cannot be reduced, so that the corrosion of the desulfurization wastewater is strong and the recycling of the desulfurization wastewater in a factory cannot be realized exists.
The current foreign wet desulfurization wastewater treatment is to use a novel desulfurization wastewater treatment technology, namely an electroflocculation technology. The main principle of the electric flocculation technology is that the soluble electrode is dissolved under the action of current to become charged ions and release electrons, the ions generated by the electrode dissolution are organically combined with OH-generated after water is extracted to generate a compound with flocculation effect, and finally the desulfurization wastewater is collected by filtration. However, the electric flocculation technology has the defects of extremely high electricity consumption, high operation cost, high risk and the like, and is not popularized and applied at present.
The invention provides a desulfurization wastewater treatment system and a desulfurization wastewater treatment method, which aim to solve the problems.
Disclosure of Invention
The invention discloses a desulfurization wastewater treatment system and a desulfurization wastewater treatment method, which aim to overcome the defects in the prior art, reduce equipment blockage, achieve satisfactory desulfurization wastewater treatment efficiency, recycle purified produced water of desulfurization wastewater as desulfurization system process water, and have the advantages of simple process flow, stable and reliable system and lower investment and operation cost.
An embodiment of a first aspect of the present invention provides a desulfurization wastewater treatment system, including:
a wastewater conditioning tank that receives and pre-stores desulfurization wastewater from the desulfurization system;
the wastewater dosing reaction box receives water discharged by the wastewater regulating tank, and is communicated with a medicament bin which provides medicament for the wastewater dosing reaction box and is used for softening the water;
the clarification and concentration tank is used for receiving water discharged by the wastewater dosing reaction tank and precipitating and clarifying the water;
the clear water tank is used for receiving water discharged by the clarification and concentration tank, a hydrochloric acid bin is communicated with the clear water tank, and the hydrochloric acid bin is used for providing hydrochloric acid for the clear water tank and adjusting the pH value of the water;
a sand filtering system for receiving water discharged from the clean water tank and sand filtering the water;
an ultrafiltration system which receives water discharged from the sand filtration system and performs ultrafiltration on the water;
a reverse osmosis system which receives the water discharged by the ultrafiltration system and is also communicated with a strong brine discharge tank, and the strong brine produced by the reverse osmosis system is discharged to the strong brine discharge tank;
the reverse osmosis water producing tank is used for receiving and storing the purified water purified and discharged by the reverse osmosis system and supplying the stored purified water to the process water tank of the desulfurization system for water supplementing and recycling.
Further, the desulfurization wastewater treatment system further comprises a backwashing system, and the backwashing system backflushes the ultrafiltration system.
Further, the sewage generated by the ultrafiltration system is supplied to the wastewater regulating reservoir.
Further, the ultrafiltration system comprises an ultrafiltration membrane, and the ultrafiltration membrane is of an external pressure type structure.
Further, the ultrafiltration membrane comprises a PVDF material.
Further, the reverse osmosis system comprises a multi-layer reverse osmosis membrane module.
Further, the medicament cartridge contains an alkaline medicament.
Further, the alkaline agent comprises sodium hydroxide or sodium carbonate.
An embodiment of the second aspect of the present invention provides a desulfurization wastewater treatment method using the desulfurization wastewater treatment system according to the embodiment of the first aspect of the present invention, the desulfurization wastewater treatment method including:
delivering desulfurization wastewater generated by a desulfurization system into a wastewater regulating tank and pre-storing the desulfurization wastewater in the wastewater regulating tank;
the desulfurization wastewater stored by the wastewater regulating tank is conveyed to a wastewater dosing reaction box by the wastewater regulating tank for softening treatment, and a medicament bin supplies medicament to the wastewater dosing reaction box to generate water containing sediment;
overflowing the water containing the sediment into a clarification and concentration tank for sedimentation, and discharging the sludge after the sedimentation after the filtration of a filter press;
the water clarified by the clarification and concentration tank enters a clear water tank, hydrochloric acid is added into the clear water tank through a hydrochloric acid bin to adjust the pH value in the clear water tank, and the pH value in the water is adjusted to be between 5.5 and 5.8;
the water with the pH value adjusted is sent to a sand filtration system for filtration;
the water treated by the sand filtration system is conveyed to an ultrafiltration system;
the water treated by the ultrafiltration system is conveyed to a reverse osmosis system, the strong brine separated by the reverse osmosis system is discharged to a strong brine discharge tank, and the purified water treated and purified by the reverse osmosis system is conveyed to a reverse osmosis water production tank; and
the reverse osmosis water producing tank stores purified water treated and purified by the reverse osmosis system, and the stored purified water is supplied to the process water tank of the desulfurization system for water supplementing and recycling.
Further, the medicament bin is provided with sodium hydroxide and/or sodium carbonate.
Further, the ultrafiltration system adopts an external pressure type structure, the ultrafiltration system comprises an ultrafiltration membrane, the ultrafiltration membrane is arranged to be cylindrical, the outer side of the cylindrical shape is a water supply side, the inner side of the cylindrical shape is a water production side, and the ultrafiltration membrane is made of PVDF (polyvinylidene fluoride) materials.
Further, the working pressure of the ultrafiltration system is 0.2-0.3 MPa, the filtration period is 45-60 min, and the design flux is not more than 50L/(m) 2 H), produced water SDI<1, turbidity of produced water<1NTU。
Further, after the ultrafiltration system is operated for a period of time, when the transmembrane pressure difference is increased to 3-4Psi, a backwashing system is started to backwash the ultrafiltration system.
Further, the backwash includes air scrubbing or water gas combined backwash.
Further, clean water is adopted in the backwashing system to feed water from the inner side of the ultrafiltration membrane, pollutants on the outer side of the ultrafiltration membrane are backwashed, and the total backwashing duration is 120-180 seconds. When the transmembrane pressure difference of the ultrafiltration system is reduced to 1Psi, stopping the operation of the backwashing system, and delivering the backwashed sewage to a wastewater regulating tank for pre-storage through a pipeline.
Further, the reverse osmosis system is provided with a multi-layer reverse osmosis module.
According to the desulfurization wastewater treatment system and the desulfurization wastewater treatment method, the agent softening and the membrane filtering are combined, and the ultrafiltration system is added after the desulfurization wastewater is subjected to dosing pretreatment softening, so that the scaling risk of the membrane concentration system is reduced, and the stable operation of the back-end system is ensured; the salt in the desulfurization wastewater is trapped in the concentrated brine by utilizing the desalination of a reverse osmosis system special for the high-salt wastewater, so that the wastewater discharge amount is reduced to less than 60% of the raw water, and the wastewater discharge and the produced water recycling rate are reduced to the maximum extent; the ultrafiltration membrane is made of PVDF, has high strength, strong oxidation resistance, acid and alkali resistance and pollution resistance, is suitable for back flushing, has long service life, and can ensure long-term stable operation of the reverse osmosis system; the method can reduce equipment blockage, achieves satisfactory desulfurization wastewater treatment efficiency, can recycle purified produced water of desulfurization wastewater as desulfurization system process water, and has simple process flow, stable and reliable system and lower investment and operation cost.
Drawings
Fig. 1 is a schematic diagram of a dewatering treatment system according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of an ultrafiltration system of a dewatering processing system in accordance with an embodiment of the present invention.
Reference numerals:
1. a waste water regulating tank; 2. a wastewater dosing reaction tank; 21. a medicament bin; 3. a clarification and concentration tank; 4. a clean water tank; 41. a hydrochloric acid bin; 5. a sand filtration system; 6. an ultrafiltration system; 61. an ultrafiltration membrane; 7. a reverse osmosis system; 71. a strong brine discharge tank; 8. reverse osmosis water producing tank; 9. a desulfurization process water tank; 10. and (5) backwashing the system.
Detailed Description
For a further understanding of the objects, construction, features, and functions of the invention, reference should be made to the following detailed description of the preferred embodiments.
As shown in fig. 1, an embodiment of a first aspect of the present invention provides a desulfurization wastewater treatment system 100, comprising:
a wastewater regulating tank 1, the wastewater regulating tank 1 receiving and pre-storing desulfurization wastewater from the desulfurization system;
the wastewater dosing reaction box 2, wherein the wastewater dosing reaction box 2 receives water discharged by the wastewater regulating tank 1, a medicament bin 21 is communicated with the wastewater dosing reaction box 2, and the medicament bin 21 provides medicament for the wastewater dosing reaction box 2 and is used for softening desulfurization wastewater and flocculating calcium and magnesium;
a clarification and concentration tank 3, wherein the clarification and concentration tank 3 receives the water discharged from the wastewater dosing reaction tank 2 and precipitates and clarifies the water containing the precipitate;
the clear water tank 4 is used for receiving water discharged by the clarification and concentration tank 3, the clear water tank 4 is communicated with a hydrochloric acid bin 41, and the hydrochloric acid bin 41 is used for providing hydrochloric acid for the clear water tank 4 and adjusting the pH value of the water;
a sand filtering system 5, wherein the sand filtering system 5 receives the water discharged by the clean water tank 4 and performs sand filtering on the water;
an ultrafiltration system 6, the ultrafiltration system 6 receiving water discharged from the sand filtration system 5, the ultrafiltration system 6 comprising an ultrafiltration membrane 61 for ultrafiltration of the water;
the reverse osmosis system 7, the reverse osmosis system 7 receives the water discharged by the ultrafiltration system 6, the reverse osmosis system 7 is also communicated with the strong brine discharge tank 71, and the strong brine generated by the reverse osmosis system 7 is discharged to the strong brine discharge tank 71;
the reverse osmosis water producing tank 8, the reverse osmosis water producing tank 8 receives and stores the purified water purified and discharged by the reverse osmosis system 7, and supplies the stored purified water to the desulfurization system process water tank 9 for water supplementing and recycling.
Further, the desulfurization wastewater treatment system 100 further includes a backwashing system 10, and after the ultrafiltration system 6 is operated for a period of time, the backwashing system 10 backwashing the ultrafiltration system 6.
Further, the sewage generated by the ultrafiltration system 6 is also supplied to the wastewater adjustment tank 1, and the wastewater adjustment tank 1 also pre-stores the sewage and treats it together with the desulfurization wastewater.
Further, as shown in fig. 2, the ultrafiltration system 6 comprises an ultrafiltration membrane 61, the ultrafiltration membrane 61 is of an external pressure type structure, the ultrafiltration membrane 61 is formed in a cylindrical shape, water to be ultrafiltered enters from the outside of the ultrafiltration membrane, ultrafiltered water enters the inside of the ultrafiltration membrane under the action of external pressure, and is discharged from the inside of the ultrafiltration membrane.
Further, the ultrafiltration membrane 61 comprises PVDF material, and the PVDF ultrafiltration membrane has higher oxidation resistance and strength performance, can resist high stress and water inlet pressure and has good recovery, so that the high-strength regeneration processes of air scrubbing, water-gas combined backwashing and the like can be performed.
Further, the reverse osmosis system 7 comprises a multi-layer reverse osmosis membrane module.
Further, the cartridge 21 contains an alkaline agent, such as sodium hydroxide or sodium carbonate, and carbonate and/or hydroxide reacts with calcium magnesium ions to form a precipitate, thereby removing the calcium magnesium ions and softening the water.
An embodiment of the second aspect of the present invention provides a desulfurization wastewater treatment method using the desulfurization wastewater treatment system 100 according to the embodiment of the first aspect of the present invention, the desulfurization wastewater treatment method including:
delivering desulfurization wastewater generated by a desulfurization system into a wastewater regulating tank 1 and pre-storing the desulfurization wastewater in the wastewater regulating tank 1;
the desulfurization wastewater stored by the wastewater regulating tank 1 is conveyed to a wastewater dosing reaction tank 2 for softening treatment by the wastewater regulating tank 1, a medicament bin 21 supplies medicaments, such as alkaline medicaments of sodium hydroxide and/or sodium carbonate and the like, to the wastewater dosing reaction tank 1, and hydroxide and/or carbonate react with calcium and magnesium ions to remove the calcium and magnesium ions and generate water containing sediment;
overflowing the water containing the sediment into a clarification and concentration tank 3 for sedimentation, and discharging the sludge after the sedimentation after the filter pressing by a filter press;
the water clarified by the clarification concentration tank 3 enters a clear water tank 4, hydrochloric acid is added into the clear water tank 4 through a hydrochloric acid bin 41 to adjust the pH value in the clear water tank 4, and the pH value in the water is adjusted to be between 5.5 and 5.8;
the water with the pH value adjusted is sent to a sand filtering system 5 for filtering;
the water treated by the sand filtration system 5 is conveyed to an ultrafiltration system 6;
the water treated by the ultrafiltration system 6 is conveyed to the reverse osmosis system 7, the strong brine separated by the reverse osmosis system 7 is discharged to the strong brine discharge tank 71, and the purified water treated and purified by the reverse osmosis system 7 is conveyed to the reverse osmosis water production tank 8; and
the reverse osmosis water producing tank 8 stores purified water treated and purified by the reverse osmosis system 7, and supplies the stored purified water to the desulfurization system process water tank 9 for water supplementing and recycling.
Further, the ultrafiltration system 6 adopts an external pressure type structure, the ultrafiltration system 6 comprises an ultrafiltration membrane 61, the ultrafiltration membrane 61 is arranged to be cylindrical, the cylindrical outer side is a water supply side, the cylindrical inner side is a water production side, water to be ultrafiltered enters from the cylindrical outer side, ultrafiltered water is discharged from the cylindrical inner side, the ultrafiltration membrane adopts PVDF (polyvinylidene fluoride) material, and the PVDF ultrafiltration membrane has higher oxidation resistance and strength performance, can withstand very high stress and water inlet pressure and has good recovery, so that the regeneration process of high strength such as air scrubbing, water-gas combined backwashing and the like can be performed.
Further, the working pressure of the ultrafiltration system 6 is 0.2-0.3 MPa, the filtration period is 45-60 min, and the design flux is not more than 50L/(m) 2 H), produced water SDI<1, turbidity of produced water<1NTU. Further, after the ultrafiltration system 6 is operated for a while, when the transmembrane pressure difference rises to 3-4Psi, the backwash system 10 is started to backwash the ultrafiltration system. The backwash may include air scrubbing or water gas combined backwash. For example, as shown in FIG. 2, the backwash system 10 uses clean water to feed water from the inside of the ultrafiltration membrane 61 to backwash contaminants outside the ultrafiltration membrane 61 for a total period of 120 to 180 seconds. When the transmembrane pressure difference of the ultrafiltration system is reduced to 1Psi, the operation of the backwashing system 10 is stopped, and the backwashed sewage is sent to the sewage regulating tank 1 for pre-storage through a pipeline.
According to the desulfurization wastewater treatment system and the desulfurization wastewater treatment method, the agent softening and the membrane filtering are combined, and the ultrafiltration system is added after the desulfurization wastewater is subjected to dosing pretreatment softening, so that the scaling risk of the membrane concentration system is reduced, and the stable operation of the back-end system is ensured; the salt in the desulfurization wastewater is trapped in the concentrated brine by utilizing the desalination of a reverse osmosis system special for the high-salt wastewater, so that the wastewater discharge amount is reduced to less than 60% of the raw water, and the wastewater discharge and the produced water recycling rate are reduced to the maximum extent; the ultrafiltration membrane is made of PVDF, has high strength, strong oxidation resistance, acid and alkali resistance and pollution resistance, is suitable for back flushing, has long service life, and can ensure long-term stable operation of the reverse osmosis system; the method can reduce equipment blockage, achieves satisfactory desulfurization wastewater treatment efficiency, can recycle purified produced water of desulfurization wastewater as desulfurization system process water, and has simple process flow, stable and reliable system and lower investment and operation cost.
Examples
Referring to fig. 1, the desulfurization wastewater treatment system comprises a wastewater regulating tank (1), a wastewater dosing reaction tank (2), a medicament bin (21), a clarification tank (3), a hydrochloric acid bin (41), a clear water tank (4), a sand filtration system (5), an ultrafiltration system (6), a backwashing system (10), a reverse osmosis system (7), a reverse osmosis water production tank (8), a strong brine discharge tank (71) and a desulfurization process water tank (9); the wastewater treatment device comprises a wastewater regulating tank (1), a wastewater dosing reaction tank (2), a clarification concentration tank (3), a clear water tank (4) and a sand filtration system (5), wherein the wastewater regulating tank, the wastewater dosing reaction tank, the clarification concentration tank, the clear water tank (4) and the sand filtration system (5) are respectively arranged on a desulfurization wastewater outlet pipeline, a medicament bin (21) is arranged above the wastewater dosing reaction tank (2), a hydrochloric acid bin (41) is arranged above the clear water tank (4), and an ultrafiltration system (6) is arranged behind the sand filtration system (5); a backwashing system (10) is arranged in front of the ultrafiltration system (6); a reverse osmosis system (7) and a wastewater regulating tank (2) are arranged behind the ultrafiltration system (6); the outlet of the reverse osmosis system (7) is provided with a reverse osmosis water production tank (8) and a strong brine discharge tank (71).
The desulfurization wastewater treatment method comprises the following steps: firstly, desulfurization wastewater generated by a desulfurization system is conveyed into a wastewater regulating tank (1) through a pipeline to be prestored, and the wastewater generated by backwashing an ultrafiltration system (6) is conveyed into the wastewater regulating tank (1) to be prestored by a backwashing system (10). The wastewater regulating tank (1) conveys desulfurization wastewater to the wastewater dosing reaction tank (2) for softening treatment, the chemical bin (21) is provided with chemicals such as sodium hydroxide, sodium carbonate and calcium hydroxide, magnesium ions dissolved in the desulfurization wastewater react with the sodium hydroxide to generate magnesium hydroxide precipitate, calcium ions dissolved in the desulfurization wastewater react with the sodium carbonate to generate calcium carbonate precipitate, at the moment, the PH value of the desulfurization wastewater is increased, and the calcium hydroxide chemical reacts with silicate in water to generate CaSiO 3 And (5) precipitation. The water containing sediment after reaction overflows into a clarification and concentration tank (3) for sedimentation, the sludge after sedimentation is discharged after being filtered by a filter press,the desulfurization wastewater clarified by the clarification concentration tank (3) enters the clean water tank (4), hydrochloric acid is added into the clean water tank (4) through the hydrochloric acid bin (41) to adjust the PH, and the PH of the desulfurization wastewater in the clean water tank (4) is specifically adjusted to be between 5.5 and 5.8. The desulfurization wastewater after PH adjustment is sent to a sand filtration system (5) for filtration through a pipeline.
The desulfurization wastewater is treated by adding drugs to react and soften through a drug bin (21) to reduce the hardness of calcium and magnesium in the water. And the PH of the desulfurization wastewater is regulated by adding hydrochloric acid, and the desulfurization wastewater is pretreated and softened after passing through a sand filtration system (5), so that the calcium and magnesium hardness in the wastewater is almost completely removed, the scaling risk of a reverse osmosis system (7) is reduced, and the stable operation of a rear-end system is ensured. Then, the wastewater treated by the sand filtration system (5) is conveyed to an ultrafiltration system (6) through a pipeline, the ultrafiltration system (6) adopts external pressure, an inner hole of the ultrafiltration membrane is taken as a water producing side, the ultrafiltration membrane adopts PVDF material, the working pressure of the ultrafiltration system (6) is 0.2-0.3 MPa, the filtration period is 45-60 min, and the design flux is not more than 50L/(m) 2 H), produced water SDI<1, turbidity of produced water<1NTU. After a period of operation of the ultrafiltration system (6), the pressure difference across the ultrafiltration membrane increases due to contamination of inorganic, organic and microorganisms in the water. When the transmembrane pressure difference rises to 3-4Psi, a backwashing system (10) is started to backwash the ultrafiltration system (6), the backwashing can be performed by air scrubbing or water-gas combined backwashing, the backwashing system (10) can adopt clean water to feed water from the inner hole of the ultrafiltration membrane, and the total duration of backwashing is 120-180 seconds. When the transmembrane pressure difference of the ultrafiltration system (6) is reduced to 1Psi, the backwashing system (10) is stopped, and the backwashed sewage is sent to the sewage regulating tank (1) through a pipeline.
The ultrafiltration system (6) is used as a middle end ring section for wastewater treatment, has the advantages of low effluent turbidity, long-term stable operation, reliable automatic control and the like, and is applied to the rear-end treatment technology; such as the stable operation of the reverse osmosis system (7) plays a very important role.
The ultrafiltration membrane of the ultrafiltration system is made of PVDF, the structure adopts external pressure type, and the area of each membrane is 50m 2 The design flux of a single ultrafiltration membrane of the ultrafiltration system (6) is not more than 50L/(m) 2 .h)。
Finally, the desulfurization wastewater treated by the ultrafiltration system (6) is conveyed to a reverse osmosis system (7) through a pipeline, the reverse osmosis system (7) is provided with a plurality of layers of reverse osmosis membrane components, water molecules and a very small amount of small molecular weight organic matters pass through the reverse osmosis membrane components, and most of soluble salts, colloids, organic matters and microorganisms in the water are removed through the characteristics of the reverse osmosis membrane. The produced water treated by the reverse osmosis system (7) enters a reverse osmosis produced water tank (8) for storage, and the process water tank (9) of the desulfurization system is subjected to water supplementing recycling through PLC control. The concentrated water separated by the reverse osmosis system (7) is discharged to a concentrated brine discharge tank (71) and is connected to a business owner wastewater discharge system. The recovery rate of the produced water of the reverse osmosis system (7) is more than 40 percent.
In the method of the present embodiment:
1) The sodium hydroxide and the sodium carbonate are added to the wastewater chemical adding reaction tank for reaction to perform softening pretreatment, the hardness of calcium and magnesium in the wastewater is basically removed, the generated precipitate is removed through sand filtration, hydrochloric acid is added to adjust the PH of water before entering the sand filtration system, suspended matters and insoluble salts in the water are removed, the scaling risk of a post-treatment reverse osmosis system is greatly reduced, and the stable operation of a rear-end system is ensured. The mechanism of the softening reaction of the medicament comprises:
①Mg 2+ +2OH - ——>Mg(OH) 2 (s)
the dissolved magnesium ions react with sodium hydroxide to generate magnesium hydroxide precipitate, wherein's' indicates that insoluble matters are generated by the reaction, namely suspended solids;
②Ca 2+ +CO 3 2- ——>CaCO 3 (s)
the dissolved calcium ions react with sodium carbonate to generate calcium carbonate precipitates, wherein's' represents that insoluble matters, namely suspended solids, are generated by the reaction;
③Ca 2+ +SiO 3 2- ——>CaSiO 3 (s)
the dissolved calcium ions react with silicate to form calcium silicate precipitates: where "s" means that the reaction takes place to form insoluble, i.e. suspended, solids.
The ultrafiltration system adopts an external pressure type filtration mode, and the ultrafiltration system takes the inner hole of the filter membrane as the water producing side, so that the ultrafiltration system is suitable for desulfurization wastewater with high suspended solids content. The PVDF ultrafiltration membrane is made of PVDF, has higher oxidation resistance and strength performance, can resist high stress and water inlet pressure, and has good restorability, so that the high-strength regeneration processes such as air scrubbing, water-gas combined backwashing and the like can be performed.
After being treated by the ultrafiltration system, the treated water enters the reverse osmosis system, water molecules and a very small amount of small molecular weight organic matters pass through a plurality of layers of reverse osmosis membranes in the reverse osmosis system, are concentrated through a collecting pipeline, and then are led to a water production pipe to be injected into a reverse osmosis water production tank. Otherwise, the substances which cannot pass through are concentrated through the other group of collecting pipelines and then are led to the strong brine discharge tank. Reverse osmosis systems utilize the characteristics of reverse osmosis membranes to remove most of the soluble salts, colloids, organics, and microorganisms from water.
After sodium hydroxide and sodium carbonate are added into a wastewater dosing reaction box to react, the PH value of desulfurization wastewater is increased, and the calcium hydroxide is added under the high pH condition to react with silicate in water to generate CaSiO 3 And precipitating to remove silicon.
The sand filter system comprises sand filter materials such as natural quartz sand, manganese sand and anthracite. Under a certain pressure, the water passes through a sand filtration system to remove insoluble and non-colloidal solid matters in the water, such as suspended solids, solid particles, mechanical impurities and the like, reduce the turbidity and SDI value of the water, and have better interception effect on the non-settled particles in the softening and settling process.
The ultrafiltration system is made of PVDF material and has extremely strong oxidation resistance, so that the ultrafiltration system can be fully sterilized in the pretreatment process without damaging the membrane element, thereby ensuring that the ultrafiltration system is free from biological pollution.
The reverse osmosis system is arranged behind the ultrafiltration system, the produced water purified by the reverse osmosis system enters the reverse osmosis water production tank, and the separated concentrated water enters the concentrated brine discharge tank for discharge.
The ultrafiltration system is connected with the backwashing system through a pipeline valve, the working pressure of the ultrafiltration system is 0.2-0.3 MPa, the filtration period is 45-60 min, the total backwashing duration is 120-180 seconds, and the design flux is not more than 50L/(m) 2 H), produced water SDI<1, producing waterTurbidity degree<1NTU。
Preferably, the reverse osmosis system adopts a parallel reverse osmosis membrane group, and the water yield is normally designed to be 5-8 m 3 And/h, the diameter of the membrane element is 8-10 inches, and the membrane flux is not more than 50L/(m) 2 H), the design temperature is considered according to 25 ℃. The recovery rate of purified water through the reverse osmosis system was > 40%.
Compared with the prior art, the beneficial effects of the embodiment include:
1. the agent is softened and sand filtration and ultrafiltration are combined, a sand filtration system and an ultrafiltration system are added after desulfurization wastewater is pretreated and softened by adding the agent, the scaling risk of the ultrafiltration system is reduced, and the stable operation of links at the rear end is ensured.
2. Aiming at high-salt wastewater, salt in the desulfurization wastewater is trapped in concentrated brine by utilizing the desalination of a reverse osmosis system, so that the discharged wastewater quantity is reduced to below 60% of raw water, and the discharged wastewater and produced water recycling rate is reduced to the maximum extent;
3. the ultrafiltration membrane is made of PVDF, has high strength, strong oxidation resistance, acid and alkali resistance and pollution resistance, is suitable for back flushing, has long service life, and can ensure long-term stable operation of the reverse osmosis system.
In the description of the present invention, it should be understood that the terms "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer" orientation or positional relationship are merely for convenience of description and to simplify the description, but do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the invention.
The invention has been described with respect to the above-described embodiments, however, the above-described embodiments are merely examples of practicing the invention. It should be noted that the disclosed embodiments do not limit the scope of the invention. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Claims (10)

1. A desulfurization wastewater treatment system comprising:
a wastewater conditioning tank that receives and pre-stores desulfurization wastewater from the desulfurization system;
the wastewater dosing reaction box receives water discharged by the wastewater regulating tank, and is communicated with a medicament bin which provides medicament for the wastewater dosing reaction box and is used for softening the water;
the clarification and concentration tank is used for receiving water discharged by the wastewater dosing reaction tank and precipitating and clarifying the water;
the clear water tank is used for receiving water discharged by the clarification and concentration tank, a hydrochloric acid bin is communicated with the clear water tank, and the hydrochloric acid bin is used for providing hydrochloric acid for the clear water tank and adjusting the pH value of the water;
a sand filtering system for receiving water discharged from the clean water tank and sand filtering the water;
an ultrafiltration system which receives water discharged from the sand filtration system and performs ultrafiltration on the water;
a reverse osmosis system which receives the water discharged by the ultrafiltration system and is also communicated with a strong brine discharge tank, and the strong brine produced by the reverse osmosis system is discharged to the strong brine discharge tank;
the reverse osmosis water producing tank is used for receiving and storing the purified water purified and discharged by the reverse osmosis system and supplying the stored purified water to the process water tank of the desulfurization system for water supplementing and recycling.
2. The desulfurization wastewater treatment system of claim 1, further comprising a backwash system that backwash the ultrafiltration system.
3. The desulfurization wastewater treatment system of claim 2, wherein the wastewater produced by the ultrafiltration system is supplied to the wastewater conditioning tank.
4. The desulfurization wastewater treatment system of claim 1, wherein the ultrafiltration system comprises an ultrafiltration membrane, the ultrafiltration membrane being of an external pressure type configuration.
5. The desulfurization wastewater treatment system of claim 1, wherein the reverse osmosis system comprises a multi-layered reverse osmosis membrane module.
6. The desulfurization wastewater treatment system of claim 1, wherein the cartridge comprises an alkaline agent.
7. A desulfurization wastewater treatment method using the desulfurization wastewater treatment system according to claim 4, comprising:
delivering desulfurization wastewater generated by a desulfurization system into a wastewater regulating tank and pre-storing the desulfurization wastewater in the wastewater regulating tank;
the desulfurization wastewater stored by the wastewater regulating tank is conveyed to a wastewater dosing reaction box by the wastewater regulating tank for softening treatment, and a medicament bin supplies medicament to the wastewater dosing reaction box to generate water containing sediment;
overflowing the water containing the sediment into a clarification and concentration tank for sedimentation, and discharging the sludge after the sedimentation after the filtration of a filter press;
the water clarified by the clarification and concentration tank enters a clear water tank, hydrochloric acid is added into the clear water tank through a hydrochloric acid bin to adjust the pH value in the clear water tank, and the pH value in the water is adjusted to be between 5.5 and 5.8;
the water with the pH value adjusted is sent to a sand filtration system for filtration;
the water treated by the sand filtration system is conveyed to an ultrafiltration system;
the water treated by the ultrafiltration system is conveyed to a reverse osmosis system, the strong brine separated by the reverse osmosis system is discharged to a strong brine discharge tank, and the purified water treated and purified by the reverse osmosis system is conveyed to a reverse osmosis water production tank; and
the reverse osmosis water producing tank stores purified water treated and purified by the reverse osmosis system, and the stored purified water is supplied to the process water tank of the desulfurization system for water supplementing and recycling.
8. The desulfurization wastewater treatment method according to claim 7, wherein after the ultrafiltration system is operated for a certain period of time, when the transmembrane pressure difference rises to 3 to 4Psi, a backwash system is started to backwash the ultrafiltration system.
9. The desulfurization wastewater treatment method according to claim 8, wherein the backwashing system uses clean water to feed water from the inner side of the ultrafiltration membrane, and backwash the contaminants on the outer side of the ultrafiltration membrane is performed for 120 to 180 seconds. When the transmembrane pressure difference of the ultrafiltration system is reduced to 1Psi, stopping the operation of the backwashing system, and delivering the backwashed sewage to a wastewater regulating tank for pre-storage through a pipeline.
10. The desulfurization wastewater treatment method according to claim 7, wherein the chemical bin contains sodium hydroxide or sodium carbonate.
CN202310177944.5A 2023-02-28 2023-02-28 Desulfurization wastewater treatment system and desulfurization wastewater treatment method Pending CN116253465A (en)

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