CN114368852A - Cold rolling acid-containing wastewater treatment system and process - Google Patents

Cold rolling acid-containing wastewater treatment system and process Download PDF

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Publication number
CN114368852A
CN114368852A CN202111531141.2A CN202111531141A CN114368852A CN 114368852 A CN114368852 A CN 114368852A CN 202111531141 A CN202111531141 A CN 202111531141A CN 114368852 A CN114368852 A CN 114368852A
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acid
reverse osmosis
containing wastewater
water
osmosis membrane
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梁宏书
鲁长炜
王鑫育
孙海志
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Tangshan Iron and Steel Group Co Ltd
HBIS Co Ltd Tangshan Branch
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Tangshan Iron and Steel Group Co Ltd
HBIS Co Ltd Tangshan Branch
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Priority to CN202111531141.2A priority Critical patent/CN114368852A/en
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
    • 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
    • C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
    • 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
    • C02F1/50—Treatment of water, waste water, or sewage by addition or application of a germicide or by oligodynamic treatment
    • 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
    • C02F1/70—Treatment of water, waste water, or sewage by reduction
    • 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
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/20—Heavy metals or heavy metal compounds
    • C02F2101/203—Iron or iron compound
    • 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
    • C02F2103/16—Nature of the water, waste water, sewage or sludge to be treated from metallurgical processes, i.e. from the production, refining or treatment of metals, e.g. galvanic wastes
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
    • C02F5/08—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents

Abstract

The invention discloses a cold-rolling acid-containing wastewater treatment system and a process, wherein the system consists of a horizontal sedimentation tank, a fiber bundle filter, an ultrafiltration membrane, an acid-resistant nanofiltration membrane and a reverse osmosis membrane unit, iron ions-containing cold-rolling acid-containing wastewater is separated into an iron salt solution through the nanofiltration system, and a reverse osmosis device is adopted to realize wastewater recycling. The system is simple and scientific in design, saves comprehensive cost and achieves the zero emission standard compared with the traditional system. The process reduces the lime consumption and the solid waste amount by replacing the traditional lime or alkali neutralization process, recovers the ferric salt in the cold rolling wastewater, recovers the hydrochloric acid, reduces the hydrochloric acid consumption of the cold rolling process, recycles the reverse osmosis produced water, reduces the water consumption of the system, and manufactures the iron oxide red product by treating the nanofiltration concentrated water through the acid regeneration process of a cold rolling plant, thereby realizing zero discharge of wastewater, reducing environmental pollution and saving pollution discharge cost.

Description

Cold rolling acid-containing wastewater treatment system and process
Technical Field
The invention belongs to the technical field of industrial wastewater treatment, and particularly relates to a cold rolling acid-containing wastewater treatment system and process.
Technical Field
With the development of industry, how to treat industrial wastewater to avoid polluting water becomes a necessary problem in the field of industrial water treatment, and a novel and advanced industrial wastewater treatment process which reduces resource consumption and can reuse resources is urgently needed.
Because the cold rolling acid-containing wastewater contains ferric salt generated by hydrochloric acid rinsing water, the prior treatment of the cold rolling acid-containing wastewater generally adopts aeration to remove Fe in water2+Is oxidized into Fe3+The precipitation is facilitated, then the hydrochloric acid in the water is neutralized by lime or alkali, the further precipitation is carried out, and the produced water is discharged after reaching the standard.
The above treatment process has the following problems: (ii) Fe2+Oxidation of Fe3+Needs aeration and consumes a large amount of energy. Hydrochloric acid in water cannot be recovered, a large amount of lime or alkali is needed for neutralization, acid and alkali consumption is extremely high, the solid waste treatment capacity is large, and the risk and cost of solid waste treatment are higher and higher. And thirdly, as the waste water neutralized by the traditional process can not be recycled and can only be discharged up to the standard, along with the stricter and stricter national standard of discharged waste water, enterprises face the overproof risk and the higher and higher running cost.
If hydrochloric acid and ferric salt in the wastewater are separated and recycled and reused or used in other processes, the operation cost of enterprises can be greatly reduced, and the environmental pollution is reduced.
Disclosure of Invention
The invention solves the technical problem of separating hydrochloric acid, ferric salt and a small amount of other impurities from cold rolling wastewater, and realizes the purposes of recycling hydrochloric acid and ferric salt and recycling water.
The technical scheme adopted by the invention is as follows:
a cold rolling acid-containing wastewater treatment system comprises the following devices which are connected in sequence: the acid-containing wastewater treatment system comprises an acid-containing wastewater adjusting tank, a horizontal flow sedimentation tank, a fiber bundle filter, an acid-resistant ultrafiltration membrane, a nanofiltration membrane and a primary reverse osmosis membrane.
Preferably, the second reverse osmosis membrane is connected behind the first reverse osmosis membrane; a third security filter and a third high-pressure pump are sequentially arranged between the first-stage reverse osmosis membrane and the second-stage reverse osmosis membrane;
an ultrafiltration water tank, a first safety filter and a first high-pressure pump are sequentially connected between the ultrafiltration membrane and the acid-resistant nanofiltration membrane;
a dilute hydrochloric acid storage pool, a second security filter and a second high-pressure pump are sequentially connected between the acid-resistant nanofiltration membrane and the primary reverse osmosis membrane;
the first-stage reverse osmosis membrane and the second-stage reverse osmosis membrane are respectively communicated with a desalting water tank;
the secondary reverse osmosis membrane is connected with a strong brine storage tank;
the acid-containing wastewater adjusting tank is communicated with the fiber bundle filter.
A cold rolling acid-containing wastewater treatment process comprises the following steps:
cold rolling acid-containing wastewater in the acid-containing wastewater adjusting tank is conveyed to a horizontal sedimentation tank through a pump to remove suspended matters, then the effluent turbidity is less than 5NTU through a fiber bundle filter, iron colloid is removed through an ultrafiltration membrane, water produced by the ultrafiltration membrane enters an ultrafiltration water tank, the water enters an acid-resistant nanofiltration membrane through a first security filter and a first high-pressure pump, monovalent anions produce water along with the acid-resistant nanofiltration membrane, the monovalent anions enter a first reverse osmosis membrane through a second security filter and a second high-pressure pump, more than 98% of ions are removed through the first reverse osmosis membrane, the water produced by the first reverse osmosis membrane is recycled and enters a desalting water tank, and Cl which cannot pass through the reverse osmosis membrane cannot be removed-And the concentrated water enters the concentrated water side of the first reverse osmosis membrane to form HCl solution for recovery.
Preferably, the HCl solution enters the concentrated water side of the first reverse osmosis membrane and enters the second reverse osmosis membrane through the third cartridge filter and the third high-pressure pump, and the water produced by the second reverse osmosis membrane enters the desalting water pool but cannot pass through Cl of the reverse osmosis membrane-And the concentrated solution enters the concentrated water side of the second reverse osmosis membrane to form HCl solution which enters a concentrated hydrochloric acid storage pool.
Preferably, the indexes of the cold rolling acid-containing wastewater are as follows: 500-1000 mg/L of suspended matter, 0-2 of pH value, 20000-50000us/cm of electric conductivity, 500-2000mg/L of chlorine radical, less than or equal to 200mg/L of hardness and less than or equal to 2500mg/L of total iron.
The indexes of acid water before entering the acid-resistant nanofiltration membrane are as follows: COD is less than or equal to 200mg/L, pH value is 0-5, conductivity is less than or equal to 50000us/cm, calcium hardness is less than or equal to 200mg/L, and SDI is less than or equal to 5.
Preferably, the filtering precision of the fiber bundle filter is 5 μm; the filtration precision of the ultrafiltration membrane is 0.05-0.1 mu m, the turbidity is less than 1NTU, and the water inlet condition of the nanofiltration membrane is met.
Preferably, a non-oxidizing bactericide, namely organic bromine or isothiazolinone, a scale inhibitor, namely HDEP, and a reducing agent, namely sodium bisulfite are added before the first safety filter; non-oxidative bactericide, namely organic bromine or isothiazolinone, scale inhibitor, namely HDEP, and reducing agent, namely sodium bisulfite are added in front of the second high-pressure pump.
Preferably, the acid-resistant nanofiltration membrane separates iron salt in the wastewater from the acid-containing wastewater, and the iron salt enters an acid regeneration process of a cold rolling mill, wherein the iron salt enters a roasting furnace, is subjected to decomposition reaction at the temperature of 560-590 ℃ to generate hydrogen chloride gas and ferric oxide particles, the waste gas is purified and then discharged into the atmosphere, and the ferric oxide particles are finally prepared into iron oxide red products.
Preferably, the monovalent anion comprises chloride ions, and the pressures of the first high-pressure pump, the second high-pressure pump and the third high-pressure pump are respectively 2.5-3.5MPa,2.5-4.1MPa and 11-14 MPa.
Preferably, the backwashing water in the fiber bundle filter is returned to the acid-containing wastewater regulating reservoir.
The cold-rolled acid-containing wastewater is stored in an acid-containing wastewater adjusting tank, the water quality of the adjusting tank is different and similar among plants, the general suspended matter is 500-1000 mg/L, the pH value is 0-2, the conductivity is 20000-50000us/cm, the chlorine content is 500-2000mg/L, the hardness is less than or equal to 200mg/L, the total iron is less than or equal to 2500mg/L, the water is conveyed to a horizontal flow sedimentation tank through a pump to remove the suspended matter, the turbidity of the outlet water is less than 5NTU through a fiber bundle filter, and the filtering precision of the fiber bundle filter is 5 mu m, so that large particles, partial colloid and COD can be removed. The ultrafiltration membrane is used for removing part of iron colloid, the filtration precision is 0.05-0.1 mu m, the turbidity is less than 1NTU, and the condition for providing water inlet of the acid-resistant nanofiltration membrane is met. And the water produced by the ultrafiltration membrane enters an ultrafiltration water tank, passes through a first security filter and a first booster pump, and enters an acid-resistant nanofiltration membrane. Non-oxidation bactericide and scale inhibitor are added before the first safety filter to ensure that the acid-resistant nanofiltration membrane is not corroded,to prevent Fe3+The ions have catalytic action on the oxidation of the acid-resistant nanofiltration membrane by the dissolved oxygen in the oxidant such as water, and a small amount of reducing agent is added to react Fe3+Reduction of ions to Fe2+. The nanofiltration can intercept Fe in the incoming water2+And (3) separating iron salt in the wastewater from the acid-containing wastewater through an acid-resistant nanofiltration membrane, and performing an acid regeneration process in a cold rolling plant to finally prepare a pure iron oxide red product. Under the acidic condition, the solubility product of the ferric salt is greatly increased, the scaling trend of a ferric salt nanofiltration membrane is avoided, the nanofiltration recovery rate can be improved to 80 percent, namely, the ferrous salt water with the concentration of 1 percent is generated, monovalent anions such as chloride ions and the like are produced along with the nanofiltration membrane, and enter the first reverse osmosis membrane through the second security filter and the second high-pressure pump, more than 98 percent of ions can be removed by the first reverse osmosis membrane, the produced water of the first reverse osmosis membrane can be recycled, and Cl is produced-And the water can not pass through the reverse osmosis membrane and can enter the reverse osmosis concentrated water side to form HCl solution for recovery. And a non-oxidation bactericide, a corrosion inhibitor and a reducing agent are added in front of the second high-pressure pump to prevent the first reverse osmosis membrane from being polluted and blocked.
The first reverse osmosis water is desalted water and enters a desalted water tank for recycling. The first reverse osmosis concentrated water is dilute hydrochloric acid, and the dilute hydrochloric acid is concentrated through the second-stage reverse osmosis to obtain concentrated hydrochloric acid for recycling.
The invention has the beneficial effects that:
the cold rolling acid-containing wastewater treatment process provided by the invention can be used for recovering hydrochloric acid and ferric salt in wastewater without using lime or alkali for neutralization, thereby realizing zero discharge of cold rolling wastewater and solid waste, greatly reducing acid and alkali consumption and reducing environmental pollution.
The invention removes Fe due to the nano film2+The reverse osmosis recovery rate of the divalent ions can be more than 85 percent, and the water recovery rate of the whole process system is more than 90 percent. The quality of produced water: the conductivity is 200-600 mus/cm, the chloride is 10-40 mg/L, the total iron is close to zero, the recovery rate of the recovered hydrochloric acid is more than 85%, and the concentration of the hydrochloric acid is 0.25-1%.
After cold-rolled acid-containing wastewater passes through the regulating tank, suspended matters in the acid-containing wastewater are removed by using the advection tank and then pass through the fiber bundle filter, the original aeration tank process is omitted, a large amount of energy is saved, and the operation cost is reduced.
The invention adopts an acid-resistant nanofiltration membrane to separate iron salt, and the nanofiltration can be used for separating Fe in acid-containing wastewater2+、Fe3+The cations are trapped, while the water and the chloride ions in the water are allowed to pass.
The invention adopts the nanofiltration membrane to recover the ferric salt, so that Fe is not required to be recovered2+Oxidation to Fe3+While preventing Fe3+The ions have catalytic oxidation effect on the nanofiltration membrane, and a small amount of reducing agent such as sodium bisulfite needs to be added in front of the nanofiltration membrane.
The invention adopts reverse osmosis to recover the water produced by the nanofiltration membrane, namely hydrochloric acid, thereby achieving the aim of recycling the hydrochloric acid, and the reverse osmosis can intercept more than 98 percent of metal ions and chloride ions.
The method adopts the membrane method to treat the incoming water, cancels the original lime or alkali neutralization process, avoids the consumption of lime or alkali, and avoids the subsequent solid waste treatment because the lime or alkali is not added and the sludge generated by the system can be recycled in the sintering system.
The invention utilizes the cold rolling acid regeneration process to treat the nanofiltration membrane concentrated water, realizes the zero discharge of the concentrated brine of the system, reduces the environmental pollution, and the roasted product is Fe2O3And can be sold as a product.
The invention recovers the reverse osmosis produced water, and reduces the water consumption of the whole system.
Drawings
FIG. 1 is a flow chart of a process commonly used at present;
FIG. 2 is a process flow diagram of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Comparative example 1
Comparative example 1 is the currently generally adopted process, and the treatment capacity of cold rolling acid wastewater of a certain steel plant is 60m3/h。
As shown in fig. 1, the main process is as follows: and (4) the acid-containing wastewater enters an acid-containing wastewater adjusting tank. The effluent of the adjusting tank is lifted to a primary neutralization tank by a lift pump, and then the effluent of the primary neutralization tank is dischargedThe water flows to the second-stage neutralization pond automatically. Adding lime milk agent into the secondary neutralization tank and carrying out aeration treatment to ensure that Fe in the wastewater2+Conversion to more readily precipitated Fe (OH)3. The effluent of the second-stage neutralization tank enters a flocculation reaction tank, then enters a clarification tank in a self-flowing manner, and a high-molecular coagulant aid is added into the flocculation reaction tank, so that flocs are further enlarged, and the precipitation effect is improved. The effluent of the clarifier is discharged into a final neutralization pond. And finally, adding a medicament into the wastewater in a neutralization tank to adjust the pH value, automatically flowing to an intermediate water tank, then discharging sludge in a clarification tank, periodically conveying the sludge to a high-density sludge tank and a sludge concentration tank through a sludge pump, and automatically flowing supernatant in the sludge concentration tank to a primary acid-containing wastewater neutralization tank. And the mud in the mud concentration tank and the high-density mud tank is conveyed to a filter press to be pressed into mud cakes to be transported outside.
Evaluation of the effects:
water quality of inlet water: pH 1.4, calcium hardness 140mg/L, conductivity: 32000us/cm, suspension: 750mg/L and 1900mg/L of total iron.
Ton wastewater treatment cost: 2.1 yuan/ton;
the mud cake production is 0.9t/h, the mud pressing cost of the filter press is calculated according to 40 yuan/ton, the solid waste treatment is 3500 yuan/ton, and the cost is converted into 58.5 yuan/ton of the treatment cost of the cold rolling acid wastewater.
Comprehensive cost of cold rolling acid wastewater: 55.2 yuan/ton (25 m is not calculated)3The per hour wastewater discharge cost after reaching the standard).
Discharging: discharge wastewater reaching the standard of 25m3/h。
Example 1
Example 1 the process of the present invention was used, and the acid wastewater treatment capacity of cold rolling in a certain iron and steel plant was 80m3/h。
As shown in fig. 2, the main process is: the acid-containing wastewater enters an acid-containing wastewater adjusting tank, suspended matters are removed by a horizontal flow sedimentation tank, and then the acid-containing wastewater enters a fiber bundle filter to further reduce the turbidity, wherein the filtering precision is 5 mu m; the turbidity of the acid-containing wastewater is controlled below 5 NTU. And after the treatment by the ultrafiltration membrane, controlling the turbidity below 1NTU, and controlling the filtration precision of the ultrafiltration membrane to be 0.05 mu m-0.1 mu m. Then hydrochloric acid and Fe are treated by an acid-resistant nanofiltration membrane2+And Fe3+Separating, and concentrating nanofiltration water (hydrochloric acid) by two-stage reverse osmosisThe nanofiltration concentrated water enters a cold rolling plant for acid regeneration process to produce iron oxide red byproducts. And because lime is not added into the horizontal sedimentation tank, the generated sludge is transported to sintering and recycling, and the generation of solid waste is avoided.
Evaluation of the effects: the nanofiltration water yield is 80%, the first-stage reverse osmosis water yield is 85%, the second-stage reverse osmosis water yield is 90%, and the hydrochloric acid concentration is 1%.
The water quality of the acid-containing wastewater entering the acid-containing wastewater adjusting tank is as follows: pH 1.2, calcium hardness 150mg/L, conductivity: 20000us/cm, 500mg/L suspended substance, 500mg/L chloride root and 1800mg/L total iron.
The indexes of acid water before entering the acid-resistant nanofiltration membrane are as follows: COD 150mg/L, pH 1.2, conductivity 36000us/cm, calcium hardness 150mg/L, SDI = 5. The pressure of the first high-pressure pump is 2.5 MPa. The adding concentration of the acid-resistant nanofiltration membrane agent is 7ppm of the adding concentration of the non-oxidizing bactericide organic bromine, 3ppm of the adding concentration of the scale inhibitor HDEP and 12ppm of the adding concentration of the reducing agent sodium bisulfite.
The water produced by the acid-resistant nanofiltration membrane enters a first-stage reverse osmosis membrane, and the adding concentration of the agent with the pressure of 3.5MPa of a second high-pressure pump is 5ppm of the adding concentration of the non-oxidized bactericide organic bromine, 2ppm of the adding concentration of the scale inhibitor HDEP, and 15ppm of the adding concentration of the reducing agent sodium bisulfite.
The water produced by the first-stage reverse osmosis membrane enters a second-stage reverse osmosis membrane, the pressure of a third high-pressure pump is 13MPa, and the adding concentration of ammonia water is 1500 ppm.
Ton wastewater treatment cost: 8.5 yuan/ton.
Solid waste treatment cost: 0
The benefits are as follows: the hydrochloric acid with the concentration of 1% is recovered at 0.08t/h, and the annual profit is 7 ten thousand yuan per 100 yuan/t. The iron oxide red product is 0.16t/h, calculated according to 6000 yuan/t, and the annual profit is 841 ten thousand yuan.
Discharging: and (4) zero emission.
Example 2
Example 2 the process of the present invention, a certain iron and steel plant, with a cold rolling acid wastewater treatment capacity of 45m3/h。
As shown in fig. 2, the main process is: the method comprises the following steps of enabling acid-containing wastewater to enter an acid-containing wastewater adjusting tank, removing suspended matters through a horizontal flow sedimentation tank, enabling the wastewater after the suspended matters are removed to enter a fiber bundle filter, and controlling the turbidity of the acid-containing wastewater to be below 5NTU (suspended matter removal). And then, performing ultrafiltration membrane treatment, and controlling the turbidity to be below 1NTU through two steps of treatment, wherein the filtration precision of the ultrafiltration membrane is 0.05 mu m-0.1 mu m. Wherein the fiber bundle filter and the ultrafiltered backwashing water enter the acid-containing wastewater adjusting tank again for re-precipitation and recycling. The ultrafiltration effluent is continuously separated from hydrochloric acid and iron ions by an acid-resistant nanofiltration membrane, nanofiltration water is concentrated by two-stage reverse osmosis, and nanofiltration concentrated water is subjected to an acid regeneration process in a cold rolling plant. The iron content of the sludge generated by the horizontal flow sedimentation tank is about 20 percent after chemical examination, and the sludge is mixed with the precipitated slurry (the iron content is 50 percent) generated by the steel-making and dust-removing process of the steel plant and then is transported to sintering for recycling, and no solid waste is generated.
Evaluation of the effects: the nanofiltration water yield is 80 percent, the first reverse osmosis water yield is 85 percent, the second reverse osmosis water yield is 90 percent, and the concentration of hydrochloric acid is 1.5 percent.
The water quality of the acid-containing wastewater entering the acid-containing wastewater adjusting tank is as follows: pH value is 2, calcium hardness is 200mg/L, conductivity is 50000us/cm, suspended matter is 1000mg/L, chloride radical is 2000mg/L, and total iron is 2500 mg/L.
The indexes of acid water before entering the acid-resistant nanofiltration membrane are as follows: COD 200mg/L, pH 2, conductivity 50000us/cm, calcium hardness 200mg/L, SDI = 4. The pressure of the first high-pressure pump is 3.5 MPa. The adding concentration of the acid-resistant nanofiltration membrane agent is 8ppm of the adding concentration of the non-oxidizing bactericide organic bromine, 4ppm of the adding concentration of the scale inhibitor HDEP and 13ppm of the adding concentration of the reducing agent sodium bisulfite.
The water produced by the acid-resistant nanofiltration membrane enters a first-stage reverse osmosis membrane, the adding concentration of the agent with the pressure of 4.1MPa of a second high-pressure pump is 3ppm of the adding concentration of the organic bromine of the non-oxidizing bactericide, 1ppm of the adding concentration of the scale inhibitor HDEP, and 16ppm of the adding concentration of the reducing agent sodium bisulfite.
The water produced by the first-stage reverse osmosis membrane enters a second-stage reverse osmosis membrane, the pressure of a third high-pressure pump is 14MPa, and the adding concentration of ammonia water is 1300 ppm.
Ton wastewater treatment cost: 8.5 yuan/ton.
Solid waste treatment cost: 0
The benefits are as follows: the hydrochloric acid with the concentration of 1.5 percent is recovered at 0.11t/h, and the annual profit is 10.6 ten thousand yuan according to 110 yuan/t. The iron oxide red product is 0.52t/h, calculated according to 6000 yuan/t, and the annual profit is 2733 ten thousand yuan.
Discharging: and (4) zero emission.
Example 3
Example 3 the process of the present invention, a certain iron and steel plant cold rolling acid wastewater treatment capacity of 60m3/h。
As shown in fig. 2, the main process is: the method comprises the following steps of enabling acid-containing wastewater to enter an acid-containing wastewater adjusting tank, removing suspended matters through a horizontal flow sedimentation tank, enabling the wastewater after the suspended matters are removed to enter a fiber bundle filter, and controlling the turbidity of the acid-containing wastewater to be below 5NTU (suspended matter removal). And then, performing ultrafiltration membrane treatment, and controlling the turbidity to be below 1NTU through two steps of treatment, wherein the filtration precision of the ultrafiltration membrane is 0.05 mu m-0.1 mu m. Wherein the fiber bundle filter and the ultrafiltered backwashing water enter the acid-containing wastewater adjusting tank again for re-precipitation and recycling. The ultrafiltration effluent is continuously separated from hydrochloric acid and iron ions by an acid-resistant nanofiltration membrane, nanofiltration water is concentrated by two-stage reverse osmosis, and nanofiltration concentrated water is subjected to an acid regeneration process in a cold rolling plant. The iron content of the sludge generated by the horizontal flow sedimentation tank is about 27 percent after chemical examination, and the sludge is mixed with the precipitated slurry (the iron content is 50 percent) generated by the steel-making and dust-removing process of the steel plant and then is transported to sintering for recycling, and no solid waste is generated.
Evaluation of the effects: the nanofiltration water yield is 80 percent, the first reverse osmosis water yield is 85 percent, the second reverse osmosis water yield is 90 percent, and the concentration of hydrochloric acid is 1.2 percent.
The water quality of the acid-containing wastewater entering the acid-containing wastewater adjusting tank is as follows: pH 1.4, calcium hardness 140mg/L, conductivity 32000us/cm, suspension: 750mg/L, 600mg/L of chloride and 1900mg/L of total iron.
The indexes of acid water before entering the acid-resistant nanofiltration membrane are as follows: COD 200mg/L, pH 1.4, conductivity 32000us/cm, calcium hardness 140mg/L, SDI = 3. The pressure of the first high-pressure pump is 2.8 MPa. The adding concentration of the acid-resistant nanofiltration membrane agent is 6ppm of the adding concentration of the non-oxidizing bactericide organic bromine, 5ppm of the adding concentration of the scale inhibitor HDEP and 14ppm of the adding concentration of the reducing agent sodium bisulfite.
The water produced by the acid-resistant nanofiltration membrane enters a first-stage reverse osmosis membrane, and the adding concentration of the agent with the pressure of 3.1MPa of a second high-pressure pump is 2ppm of the adding concentration of the non-oxidized bactericide organic bromine, 2ppm of the adding concentration of the scale inhibitor HDEP, and 15ppm of the adding concentration of the reducing agent sodium bisulfite.
The water produced by the first-stage reverse osmosis membrane enters a second-stage reverse osmosis membrane, the pressure of a third high-pressure pump is 13MPa, and the adding concentration of ammonia water is 1300 ppm.
The benefits are as follows: the hydrochloric acid with the concentration of 1.2 percent is recovered at 0.16t/h, and the annual profit is 14 ten thousand yuan per 100 yuan per t. The iron oxide red product is 0.19t/h, calculated according to 6000 yuan/t, and the annual profit is 998 ten thousand yuan.
Discharging: and (4) zero emission.
Example 4
Example 4 the process of the present invention, which has a cold rolling acid wastewater treatment capacity of 30m in a certain iron and steel plant, was used3/h。
As shown in fig. 2, the main process is: the method comprises the following steps of enabling acid-containing wastewater to enter an acid-containing wastewater adjusting tank, removing suspended matters through a horizontal flow sedimentation tank, enabling the wastewater after the suspended matters are removed to enter a fiber bundle filter, and controlling the turbidity of the acid-containing wastewater to be below 5NTU (suspended matter removal). And then, performing ultrafiltration membrane treatment, and controlling the turbidity to be below 1NTU through two steps of treatment, wherein the filtration precision of the ultrafiltration membrane is 0.05 mu m-0.1 mu m. Wherein the fiber bundle filter and the ultrafiltered backwashing water enter the acid-containing wastewater adjusting tank again for re-precipitation and recycling. The ultrafiltration effluent is continuously separated from hydrochloric acid and iron ions by an acid-resistant nanofiltration membrane, nanofiltration water is concentrated by two-stage reverse osmosis, and nanofiltration concentrated water is subjected to an acid regeneration process in a cold rolling plant. The iron content of the sludge generated by the horizontal flow sedimentation tank is about 24 percent after chemical examination, and the sludge is mixed with the precipitation slurry (iron content is 45 percent) of the steel-making and dust-removing process of the steel plant and then is transported to sintering for recycling, and no solid waste is generated.
Evaluation of the effects: the nanofiltration water yield is 80 percent, the first reverse osmosis water yield is 85 percent, the second reverse osmosis water yield is 90 percent, and the concentration of hydrochloric acid is 1.6 percent.
The water quality of the acid-containing wastewater entering the acid-containing wastewater adjusting tank is as follows: pH 1.4, calcium hardness 120mg/L, conductivity: 32000us/cm, suspension: 560mg/L, 900mg/L chloride and 2000mg/L total iron.
The indexes of acid water before entering the acid-resistant nanofiltration membrane are as follows: COD 200mg/L, pH 1.4, conductivity 32000us/cm, calcium hardness 120mg/L, SDI = 3. The pressure of the first high-pressure pump is 2.6 MPa. The adding concentration of the acid-resistant nanofiltration membrane agent is 5ppm of the adding concentration of the non-oxidizing bactericide organic bromine, 5ppm of the adding concentration of the scale inhibitor HDEP and 15ppm of the adding concentration of the reducing agent sodium bisulfite.
The water produced by the acid-resistant nanofiltration membrane enters a first-stage reverse osmosis membrane, and the adding concentration of the agent with the pressure of 2.7MPa in the second high-pressure pump is 3ppm of the adding concentration of the non-oxidized bactericide organic bromine, 3ppm of the adding concentration of the scale inhibitor HDEP, and 16ppm of the adding concentration of the reducing agent sodium bisulfite.
And the water produced by the first-stage reverse osmosis membrane enters a second-stage reverse osmosis membrane, the pressure of a third high-pressure pump is 12MPa, and the adding concentration of ammonia water is 1600 ppm.
The benefits are as follows: the recovery concentration of hydrochloric acid is 1.6 percent, and the recovery rate is 0.07t/h, and the annual profit is 4.95 ten thousand yuan per 110 yuan/t. The iron oxide red product is 0.35t/h, calculated according to 6000 yuan/t, and the annual profit is 1822 ten thousand yuan.
Discharging: and (4) zero emission.
In conclusion, the novel cold-rolling acid-containing wastewater treatment process provided by the patent not only realizes zero discharge of acid-containing wastewater, but also reduces the comprehensive treatment cost of the acid-containing wastewater, and the traditional scheme is integrated into 55.2 yuan/ton (not calculating 25 m)3The per hour wastewater discharge cost after reaching the standard). And the treatment cost of the acid-containing wastewater of the patent process is only 8.5 yuan/ton (the profit of hydrochloric acid and iron oxide red byproducts is not contained). Most importantly, the pollution of solid waste and wastewater discharge to the environment is avoided.

Claims (10)

1. The cold rolling acid-containing wastewater treatment system is characterized by comprising the following devices which are connected in sequence: the acid-containing wastewater treatment system comprises an acid-containing wastewater adjusting tank, a horizontal flow sedimentation tank, a fiber bundle filter, an acid-resistant ultrafiltration membrane, a nanofiltration membrane and a primary reverse osmosis membrane.
2. The cold-rolling acid-containing wastewater treatment system according to claim 1, characterized in that a secondary reverse osmosis membrane is connected behind the primary reverse osmosis membrane; a third security filter and a third high-pressure pump are sequentially arranged between the first-stage reverse osmosis membrane and the second-stage reverse osmosis membrane;
an ultrafiltration water tank, a first safety filter and a first high-pressure pump are sequentially connected between the ultrafiltration membrane and the acid-resistant nanofiltration membrane;
a dilute hydrochloric acid storage pool, a second security filter and a second high-pressure pump are sequentially connected between the acid-resistant nanofiltration membrane and the primary reverse osmosis membrane;
the first-stage reverse osmosis membrane and the second-stage reverse osmosis membrane are respectively communicated with a desalting water tank;
the secondary reverse osmosis membrane is connected with a strong brine storage tank;
the acid-containing wastewater adjusting tank is communicated with the fiber bundle filter.
3. A cold rolling acid-containing wastewater treatment process is characterized in that the cold rolling acid-containing wastewater treatment system of claim 1 or 2 is used, and comprises the following steps:
cold rolling acid-containing wastewater in the acid-containing wastewater adjusting tank is conveyed to a horizontal sedimentation tank through a pump to remove suspended matters, then the effluent turbidity is less than 5NTU through a fiber bundle filter, iron colloid is removed through an ultrafiltration membrane, water produced by the ultrafiltration membrane enters an ultrafiltration water tank, the water enters an acid-resistant nanofiltration membrane through a first security filter and a first high-pressure pump, monovalent anions produce water along with the acid-resistant nanofiltration membrane, the monovalent anions enter a first reverse osmosis membrane through a second security filter and a second high-pressure pump, more than 98% of ions are removed through the first reverse osmosis membrane, the water produced by the first reverse osmosis membrane is recycled and enters a desalting water tank, and Cl which cannot pass through the reverse osmosis membrane cannot be removed-And the concentrated water enters the concentrated water side of the first reverse osmosis membrane to form HCl solution for recovery.
4. The process for treating cold-rolled acid-containing wastewater according to claim 3, characterized in that HCl solution formed in the concentrated water side of the first reverse osmosis membrane enters the second reverse osmosis membrane through the third cartridge filter and the third high-pressure pump, and the produced water of the second reverse osmosis membrane enters the desalting water pool and cannot pass through Cl of the reverse osmosis membrane-And the concentrated solution enters the concentrated water side of the second reverse osmosis membrane to form HCl solution which enters a concentrated hydrochloric acid storage pool.
5. The cold rolling acid-containing wastewater treatment process according to claim 3, characterized in that indexes of the cold rolling acid-containing wastewater are as follows: 500-1000 mg/L of suspended matter, 0-2 of pH value, 20000-50000us/cm of electric conductivity, 500-2000mg/L of chlorine, less than 200mg/L of hardness and less than 2500mg/L of total iron.
6. The cold-rolling acid-containing wastewater treatment process according to claim 3, characterized in that the filtering precision of the fiber bundle filter is 5 μm; the filtration precision of the ultrafiltration membrane is 0.05-0.1 mu m, the turbidity is less than 1NTU, and the water inlet condition of the nanofiltration membrane is met.
7. The process for treating the cold-rolled acid-containing wastewater according to claim 3, characterized in that a non-oxidative bactericide, namely organic bromine or isothiazolinone, a scale inhibitor, namely HDEP, a reducing agent, namely sodium bisulfite, is added before the first safety filter; non-oxidative bactericide, namely organic bromine or isothiazolinone, scale inhibitor, namely HDEP, and reducing agent, namely sodium bisulfite are added in front of the second high-pressure pump.
8. The process for treating the cold-rolled acid-containing wastewater according to claim 3, wherein the acid-resistant nanofiltration membrane is used for separating iron salt in the wastewater from the acid-containing wastewater, and the iron salt enters an acid regeneration process of a cold rolling plant, wherein the iron salt enters a roasting furnace and undergoes decomposition reaction at the temperature of 560-590 ℃ to generate hydrogen chloride gas and ferric oxide particles, the waste gas is purified and discharged into the atmosphere, and the ferric oxide particles are finally prepared into iron oxide red products.
9. The cold-rolling acid-containing wastewater treatment process of claim 3, wherein the monovalent anion comprises chloride ions, and the pressures of the first high-pressure pump, the second high-pressure pump and the third high-pressure pump are respectively 2.5-3.5MPa,2.5-4.1MPa and 11-14 MPa.
10. The cold-rolling acid-containing wastewater treatment process is characterized in that backwashing water in the fiber bundle filter is returned to an acid-containing wastewater regulating reservoir.
CN202111531141.2A 2021-12-14 2021-12-14 Cold rolling acid-containing wastewater treatment system and process Pending CN114368852A (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101786734A (en) * 2009-09-08 2010-07-28 刘春喜 Process for treating acid waste water containing copper, nickel and the like by membrane method
CN110316873A (en) * 2019-07-22 2019-10-11 唐山钢铁集团有限责任公司 A kind of regeneration liquid waste recycling technique
CN111056653A (en) * 2019-12-13 2020-04-24 首钢京唐钢铁联合有限责任公司 Cold rolling wastewater treatment system and method
CN111186931A (en) * 2019-03-26 2020-05-22 麦王环境技术股份有限公司 Stainless steel pickling wastewater recycling equipment and process
CN113582468A (en) * 2021-08-27 2021-11-02 宝武水务科技有限公司 Stainless steel pickling waste acid liquid treatment system and treatment method

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101786734A (en) * 2009-09-08 2010-07-28 刘春喜 Process for treating acid waste water containing copper, nickel and the like by membrane method
CN111186931A (en) * 2019-03-26 2020-05-22 麦王环境技术股份有限公司 Stainless steel pickling wastewater recycling equipment and process
CN110316873A (en) * 2019-07-22 2019-10-11 唐山钢铁集团有限责任公司 A kind of regeneration liquid waste recycling technique
CN111056653A (en) * 2019-12-13 2020-04-24 首钢京唐钢铁联合有限责任公司 Cold rolling wastewater treatment system and method
CN113582468A (en) * 2021-08-27 2021-11-02 宝武水务科技有限公司 Stainless steel pickling waste acid liquid treatment system and treatment method

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