Sewage treatment process based on UV-Fenton

Abstract

The invention relates to the technical field of sewage treatment, in particular to a sewage treatment process based on UV-Fenton, which comprises the following steps: S1, pretreatment; s2, carrying out UV photolysis; s3, carrying out Fenton oxidation; s4, precipitating; s5, performing ultrafiltration; and S6, sludge recovery. According to the method, two technologies of UV photolysis and Fenton oxidation are combined, stable complexes formed by various complexing agents and heavy metal ions in the wastewater can be effectively destroyed, free heavy metal ions are released, the removal rate of the heavy metal ions is increased, free radicals generated by UV photolysis and hydroxyl free radicals generated by Fenton oxidation cooperate with each other, the oxidation capacity is enhanced, and the removal rate of the heavy metal ions is increased. The nickel-containing complex wastewater treatment device improves the treatment efficiency, reduces the use amount of chemicals, reduces the treatment cost, is suitable for treating various nickel-containing complex wastewater, and particularly has a good treatment effect on some complex systems which are difficult to biodegrade and chemically precipitate.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, in particular to a sewage treatment process based on UV-Fenton. Background Art

[0002] Heavy metal wastewater typically contains large quantities of heavy metal ions, such as nickel, copper, and zinc, which often form stable complexes with organic chelating agents. Traditional heavy metal wastewater treatment methods, such as chemical precipitation and ion exchange, while capable of removing heavy metal ions to a certain extent, are ineffective for removing complexed heavy metals. Even when combined with advanced oxidation technologies such as the Fenton process, it is difficult to completely destroy the complex structure, resulting in high concentrations of heavy metal ions in the treated wastewater. Summary of the Invention

[0003] The purpose of the present invention is to provide a sewage treatment process based on UV-Fenton to solve the problems raised in the above background technology.

[0004] To achieve the above object, the present invention provides the following technical solution: a sewage treatment process based on UV-Fenton, comprising the following steps:

[0005] S1. Pretreatment: remove suspended solids and oily substances in sewage. The concentration of free metal ions in sewage is 50-300 mg / L;

[0006] S2. UV photolysis: Pump the sewage into the UV photolysis reactor, first add hydrogen peroxide to the sewage, the amount of hydrogen peroxide added is 0.1% to 1.0% of the sewage mass, then turn on the UV lamp and irradiate the sewage continuously for 30 to 60 minutes;

[0007] S3, Fenton oxidation: Pump the sewage into the Fenton reactor, first add an acid pH regulator to the sewage to adjust the pH value of the sewage to 2-3, then add ferrous sulfate powder to the sewage, the amount of ferrous sulfate powder added is 0.5% to 2.0% of the sewage mass, and finally keep the sewage in the Fenton reactor for 60-120 minutes;

[0008] S4. Sedimentation: Pump the sewage into the sedimentation tank, first add alkali solution to the sewage to adjust the pH value of the sewage to 7-8, then add polyacrylamide to the sewage, the amount of polyacrylamide added is 0.1%-0.3% of the sewage mass, and finally let the sewage stand in the sedimentation tank for 60-120 minutes;

[0009] S5, ultrafiltration: The supernatant of the sedimentation tank is pumped into the ultrafiltration water purification equipment, the filtrate is directly discharged, and the filtrate is recovered to the sludge treatment system;

[0010] S6. Sludge recovery: The sediment in the sedimentation tank is recovered to the sludge treatment system.

[0011] Optionally, the UV photolysis reactor is a cylindrical container, and the UV lamp is a straight tube low-pressure mercury lamp.

[0012] Optionally, the axis of the UV lamp coincides with the axis of the UV photolysis reactor, and the sewage submerges the UV lamp.

[0013] Optionally, the ultraviolet light emitted by the UV lamp has a wavelength of 185 to 254 nm.

[0014] Optionally, the acid pH regulator is dilute hydrochloric acid or dilute sulfuric acid.

[0015] Optionally, the alkali solution is sodium hydroxide or calcium hydroxide.

[0016] Optionally, the sedimentation tank is an inclined tube sedimentation tank or an inclined plate sedimentation tank.

[0017] Optionally, the filtration accuracy of the ultrafiltration water purification equipment is 0.005 to 0.01 μm.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention combines UV photolysis and Fenton oxidation technologies to effectively destroy the stable complexes formed by various chelating agents and heavy metal ions in wastewater, release free heavy metal ions, and improve the removal rate of heavy metal ions;

[0020] 2. The free radicals generated by UV photolysis and the hydroxyl radicals generated by Fenton oxidation in the present invention cooperate with each other, thereby enhancing the oxidation capacity and improving the treatment efficiency, while reducing the amount of reagents used and reducing the treatment cost. It is suitable for treating a variety of nickel-containing complex wastewaters, especially for some complex systems that are difficult to biodegrade and chemically precipitate. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] Example 1: The present invention provides a wastewater treatment process based on UV-Fenton, comprising the following steps:

[0023] S1. Pretreatment: remove suspended solids and oily substances in sewage. The concentration of free metal ions in sewage is 50 mg / L;

[0024] S2. UV photolysis: Pump the sewage into the UV photolysis reactor, first add hydrogen peroxide to the sewage, the amount of hydrogen peroxide added is 0.1% of the sewage mass, then turn on the UV lamp, the UV lamp emits ultraviolet light with a wavelength of 185nm, and continuously irradiate the sewage for 30 minutes;

[0025] S3. Fenton oxidation: Pump the sewage into the Fenton reactor, first add dilute hydrochloric acid to the sewage to adjust the pH value of the sewage to 2, then add ferrous sulfate powder to the sewage, the amount of ferrous sulfate powder added is 0.5% of the sewage mass, and finally keep the sewage in the Fenton reactor for 60 minutes;

[0026] S4. Sedimentation: Pump the sewage into the sedimentation tank, first add alkali solution to the sewage to adjust the pH value of the sewage to 7, then add polyacrylamide to the sewage, the amount of polyacrylamide added is 0.1% of the sewage mass, and finally let the sewage stand in the sedimentation tank for 60 minutes;

[0027] S5, ultrafiltration: The supernatant of the sedimentation tank is pumped into the ultrafiltration water purification equipment. The filtration accuracy of the ultrafiltration water purification equipment is 0.01μm. The filtrate is directly discharged and the filtrate is recovered to the sludge treatment system;

[0028] S6. Sludge recovery: The sediment in the sedimentation tank is recovered to the sludge treatment system.

[0029] Example 2: The present invention provides a wastewater treatment process based on UV-Fenton, comprising the following steps:

[0030] S1. Pretreatment: remove suspended solids and oily substances in sewage. The concentration of free metal ions in sewage is 105 mg / L;

[0031] S2. UV photolysis: Pump the sewage into the UV photolysis reactor, first add hydrogen peroxide to the sewage, the amount of hydrogen peroxide added is 0.4% of the sewage mass, then turn on the UV lamp, the UV lamp emits ultraviolet light with a wavelength of 200nm, and continuously irradiate the sewage for 40 minutes;

[0032] S3. Fenton oxidation: Pump the sewage into the Fenton reactor, first add dilute hydrochloric acid to the sewage to adjust the pH value of the sewage to 2, then add ferrous sulfate powder to the sewage, the amount of ferrous sulfate powder added is 1.0% of the sewage mass, and finally keep the sewage in the Fenton reactor for 80 minutes;

[0033] S4. Sedimentation: Pump the sewage into the sedimentation tank, first add alkali solution to the sewage to adjust the pH value of the sewage to 7, then add polyacrylamide to the sewage, the amount of polyacrylamide added is 0.2% of the sewage mass, and finally let the sewage stand in the sedimentation tank for 80 minutes;

[0034] S5, ultrafiltration: The supernatant of the sedimentation tank is pumped into the ultrafiltration water purification equipment. The filtration accuracy of the ultrafiltration water purification equipment is 0.01μm. The filtrate is directly discharged and the filtrate is recovered to the sludge treatment system;

[0035] S6. Sludge recovery: The sediment in the sedimentation tank is recovered to the sludge treatment system.

[0036] Example 3: The present invention provides a wastewater treatment process based on UV-Fenton, comprising the following steps:

[0037] S1. Pretreatment: Remove suspended solids and oily substances in sewage. The concentration of free metal ions in sewage is 198 mg / L;

[0038] S2. UV photolysis: Pump the sewage into the UV photolysis reactor, first add hydrogen peroxide to the sewage, the amount of hydrogen peroxide added is 0.8% of the sewage mass, then turn on the UV lamp, the UV lamp emits ultraviolet light with a wavelength of 225nm, and continuously irradiate the sewage for 50 minutes;

[0039] S3, Fenton oxidation: Pump the sewage into the Fenton reactor, first add dilute sulfuric acid to the sewage to adjust the pH value of the sewage to 2, then add ferrous sulfate powder to the sewage, the amount of ferrous sulfate powder added is 1.5% of the sewage mass, and finally let the sewage stay in the Fenton reactor for 100 minutes;

[0040] S4. Sedimentation: Pump the sewage into the sedimentation tank, first add alkali solution to the sewage to adjust the pH value of the sewage to 8, then add polyacrylamide to the sewage, the amount of polyacrylamide added is 0.2% of the sewage mass, and finally let the sewage stand in the sedimentation tank for 100 minutes;

[0041] S5, ultrafiltration: The supernatant of the sedimentation tank is pumped into the ultrafiltration water purification equipment. The filtration accuracy of the ultrafiltration water purification equipment is 0.01μm. The filtrate is directly discharged and the filtrate is recovered to the sludge treatment system;

[0042] S6. Sludge recovery: The sediment in the sedimentation tank is recovered to the sludge treatment system.

[0043] Example 4: The present invention provides a wastewater treatment process based on UV-Fenton, comprising the following steps:

[0044] S1. Pretreatment: Remove suspended solids and oily substances in sewage. The concentration of free metal ions in sewage is 276 mg / L;

[0045] S2. UV photolysis: Pump the sewage into the UV photolysis reactor, first add hydrogen peroxide to the sewage, the amount of hydrogen peroxide added is 1.0% of the sewage mass, then turn on the UV lamp, the UV lamp emits ultraviolet light with a wavelength of 254nm, and continuously irradiate the sewage for 60 minutes;

[0046] S3, Fenton oxidation: Pump the sewage into the Fenton reactor, first add dilute sulfuric acid to the sewage to adjust the pH value of the sewage to 3, then add ferrous sulfate powder to the sewage, the amount of ferrous sulfate powder added is 2.0% of the sewage mass, and finally keep the sewage in the Fenton reactor for 120 minutes;

[0047] S4. Sedimentation: Pump the sewage into the sedimentation tank, first add alkali solution to the sewage to adjust the pH value of the sewage to 8, then add polyacrylamide to the sewage, the amount of polyacrylamide added is 0.3% of the sewage mass, and finally let the sewage stand in the sedimentation tank for 120 minutes;

[0048] S5, ultrafiltration: The supernatant of the sedimentation tank is pumped into the ultrafiltration water purification equipment. The filtration accuracy of the ultrafiltration water purification equipment is 0.01μm. The filtrate is directly discharged and the filtrate is recovered to the sludge treatment system;

[0049] S6. Sludge recovery: The sediment in the sedimentation tank is recovered to the sludge treatment system.

[0050] Example 5: The present invention provides a wastewater treatment process based on UV-Fenton, comprising the following steps:

[0051] S1. Pretreatment: remove suspended solids and oily substances in sewage. The concentration of free metal ions in sewage is 300 mg / L;

[0052] S2. UV photolysis: Pump the sewage into the UV photolysis reactor, first add hydrogen peroxide to the sewage, the amount of hydrogen peroxide added is 1.0% of the sewage mass, then turn on the UV lamp, the UV lamp emits ultraviolet light with a wavelength of 254nm, and continuously irradiate the sewage for 60 minutes;

[0053] S3, Fenton oxidation: Pump the sewage into the Fenton reactor, first add dilute sulfuric acid to the sewage to adjust the pH value of the sewage to 3, then add ferrous sulfate powder to the sewage, the amount of ferrous sulfate powder added is 2.0% of the sewage mass, and finally keep the sewage in the Fenton reactor for 120 minutes;

[0054] S4. Sedimentation: Pump the sewage into the sedimentation tank, first add alkali solution to the sewage to adjust the pH value of the sewage to 8, then add polyacrylamide to the sewage, the amount of polyacrylamide added is 0.3% of the sewage mass, and finally let the sewage stand in the sedimentation tank for 120 minutes;

[0055] S5, ultrafiltration: The supernatant of the sedimentation tank is pumped into the ultrafiltration water purification equipment. The filtration accuracy of the ultrafiltration water purification equipment is 0.01μm. The filtrate is directly discharged and the filtrate is recovered to the sludge treatment system;

[0056] S6. Sludge recovery: The sediment in the sedimentation tank is recovered to the sludge treatment system.

[0057] In Examples 1-5, the UV photolysis reactor was a cylindrical vessel, and the UV lamp was a straight-tube low-pressure mercury lamp. The axis of the UV lamp coincided with the axis of the UV photolysis reactor. During UV photolysis, the wastewater was submerged in the UV lamp. The sedimentation tank employed an inclined plate sedimentation tank, and the wastewater flowed horizontally within the sedimentation tank.

[0058] Performance testing

[0059] Test Details: Water samples (approximately 500 mL each) were collected at each stage of the UV-Fenton process. The nickel ion concentration in the water samples was measured using a UV-visible spectrophotometer. The test results are recorded in Table 1. The nickel ion removal efficiency, η, at each stage of the UV-Fenton process was calculated using the following formula: η = (nickel ion concentration before pretreatment - nickel ion concentration at the current stage) / nickel ion concentration before pretreatment × 100%.

[0060] Table 1

[0061]

[0062] As shown in Table 1, UV photolysis has limited effectiveness in removing nickel ions, but the removal rate increases with increasing amounts of hydrogen peroxide and prolonged irradiation time. Example 5 has the highest removal rate, while Example 1 has the lowest. UV photolysis primarily acts on the complexing agent, releasing some free nickel ions.

[0063] The Fenton oxidation stage significantly removes nickel ions, with removal rates ranging from 66.4% to 72.9%. The hydroxyl radicals produced by the Fenton oxidation reaction can further oxidize and destroy the complexing agent, releasing more free nickel ions and promoting nickel ion precipitation.

[0064] The precipitation stage adjusts the pH to alkaline, causing nickel ions to precipitate as nickel hydroxide, with a removal rate between 90.2% and 92.5%. Precipitation is a key step in nickel ion removal and effectively reduces the nickel ion concentration in water.

[0065] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A wastewater treatment process based on UV-Fenton, characterized in that: The following steps are involved: S1. Pretreatment: remove suspended solids and oily substances in sewage. The concentration of free metal ions in sewage is 50-300 mg / L; S2. UV photolysis: Pump the sewage into the UV photolysis reactor, first add hydrogen peroxide to the sewage, the amount of hydrogen peroxide added is 0.1% to 1.0% of the sewage mass, then turn on the UV lamp and irradiate the sewage continuously for 30 to 60 minutes; S3, Fenton oxidation: Pump the sewage into the Fenton reactor, first add an acid pH regulator to the sewage to adjust the pH value of the sewage to 2-3, then add ferrous sulfate powder to the sewage, the amount of ferrous sulfate powder added is 0.5% to 2.0% of the sewage mass, and finally keep the sewage in the Fenton reactor for 60-120 minutes; S4. Sedimentation: Pump the sewage into the sedimentation tank, first add alkali solution to the sewage to adjust the pH value of the sewage to 7-8, then add polyacrylamide to the sewage, the amount of polyacrylamide added is 0.1%-0.3% of the sewage mass, and finally let the sewage stand in the sedimentation tank for 60-120 minutes; S5, ultrafiltration: The supernatant of the sedimentation tank is pumped into the ultrafiltration water purification equipment, the filtrate is directly discharged, and the filtrate is recovered to the sludge treatment system; S6. Sludge recovery: The sediment in the sedimentation tank is recovered to the sludge treatment system.

2. A UV-Fenton based sewage treatment process according to claim 1, characterized in that, The UV photolysis reactor is a cylindrical container, and the UV lamp is a straight tube low-pressure mercury lamp.

3. A UV-Fenton based sewage treatment process according to claim 2, characterized in that, The axis of the UV lamp coincides with the axis of the UV photolysis reactor, and the sewage submerges the UV lamp.

4. A UV-Fenton based sewage treatment process according to claim 1, characterized in that: The ultraviolet light emitted by the UV lamp has a wavelength of 185 to 254 nm.

5. A UV-Fenton based sewage treatment process according to claim 1, characterized in that: The acid pH regulator is dilute hydrochloric acid or dilute sulfuric acid.

6. A UV-Fenton based sewage treatment process according to claim 1, characterized in that: The alkali solution is sodium hydroxide or calcium hydroxide.

7. A UV-Fenton based sewage treatment process according to claim 1, characterized in that: The sedimentation tank is an inclined tube sedimentation tank or an inclined plate sedimentation tank.

8. The UV-Fenton-based sewage treatment process according to claim 1, characterized in that: The filtration accuracy of the ultrafiltration water purification equipment is 0.005-0.01 μm.

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