A coal gasification wastewater deoiling and decolorization pretreatment system

Abstract

The invention relates to the field of environmental protection, and in particular to a coal gasification wastewater degreasing and decolorizing pretreatment system. The method provides a coal gasification wastewater degreasing and decolorizing pretreatment method. The coal gasification wastewater is passed through an oil separator, an electrolytic cell (one), an electrolytic cell (two), and a coagulation sedimentation tank to remove turbidity, suspended solids, COD, ammonia nitrogen, total nitrogen, total phosphorus, and cyanide in the wastewater, and the treated wastewater can meet discharge standards. The coagulant prepared by the invention has dense internal clusters and presents a petal-like structure with spatial three-dimensional wrinkles. The structure can effectively enhance the adsorption, bridging, and net-catching and sweeping effects of the coagulant. When treating coal gasification wastewater, flocs are generated quickly with large particle size, and the structure of the formed flocs is denser.

Description

Technical Field

[0001] The present invention relates to the field of environmental protection, in particular to a coal gasification wastewater degreasing and decolorization pretreatment system. Background Art

[0002] Coal gasification wastewater is a type of coking wastewater, a high-concentration organic industrial wastewater generated during the coal-to-coke production, coal gas purification, and coking product recovery processes. The water has a complex composition, high pollutant concentrations, and is difficult to biodegrade. The wastewater contains large amounts of organic pollutants such as phenols, biphenyls, pyridine, indole, and quinoline.

[0003] CN201010558335.7: Preparation of polyferric chloride phosphate coagulant, using waste phosphate slag produced by steel phosphating as raw material, the coagulant is particularly suitable for treating oily colored industrial wastewater. The product of the present invention is prepared using phosphate slag, industrial hydrochloric acid, wherein the HCl content (weight ratio) is ≥30%, and ferrous phosphate (industrial product) as raw materials. The phosphate slag and industrial hydrochloric acid are polymerized in a certain ratio to produce polyferric chloride phosphate, a clear orange-red liquid. When used for water supply and sewage treatment, the polyferric chloride phosphate coagulant of the present invention has the characteristics of high oil removal and decolorization efficiency, low dosage of reagents, and a wide range of reagent dosages compared to existing coagulants. No secondary pollution is generated during the production and processing of this product; the production process is simple, and the waste phosphate slag is used as raw material, so the production cost is low, and therefore the product of the present invention is inexpensive.

[0004] CN02138239.5: Polyferric phosphate coagulant and its preparation method, relates to a polyferric phosphate coagulant produced using waste phosphate slag produced by steel phosphating as raw material and its preparation method. The coagulant is particularly suitable for treating oily and colored industrial wastewater. The product of the present invention is prepared using phosphate slag, industrial hydrochloric acid (wherein the HCl content (by weight) is ≥30%), and ferrous phosphate (industrial product) as raw materials. The phosphate slag and industrial hydrochloric acid are polymerized in a certain ratio to produce a clear orange-red liquid of polyferric phosphate. When used for water supply and sewage treatment, the polyferric phosphate coagulant of the present invention has the characteristics of high oil removal and decolorization efficiency, low dosage of reagents, and a wide range of reagent dosages compared to existing coagulants. The production and processing of this product does not generate secondary pollution. The production process is simple, and the use of waste phosphate slag as raw material has low production costs, so the product of the present invention is inexpensive.

[0005] CN200310103431.2: The present invention provides a wastewater purifier, its preparation method, and application, relating to the field of sewage treatment. The wastewater purifier comprises a blend of attapulgite, an inorganic filler containing silica, and an acidified high-valent metal salt. It is obtained by acidifying a high-valent metal salt solution to a pH of 1 to 3, uniformly mixing it with the other components, and drying it. This wastewater purifier combines coagulation and adsorption functions, and its treatment effect is largely unaffected by factors such as the water environment, pollution level, and wastewater type. It offers stable treatment results and a wide range of applications, particularly for the initial purification of severely polluted industrial wastewater. Its preparation method and water treatment process are simple and easy to operate, thus promising broad prospects for widespread application.

[0006] The above patents and existing technologies have problems such as large investment, long process, high operating cost, and high cost of treating the miscellaneous salts generated by zero emission in the coal gasification wastewater treatment system. Summary of the Invention

[0007] In view of the above-mentioned shortcomings of the prior art, the present invention proposes a coal gasification wastewater degreasing and decolorization pretreatment system, which generates flocs at a fast speed and with large particle size when treating coal gasification wastewater, and the structure of the formed flocs is denser, with low operating costs and high treatment efficiency.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] S1: Take 160-200 parts by mass of coal gasification wastewater and pass it through a grease trap to remove most of the oil;

[0010] S2: Electrolysis is carried out in electrolytic cell (1) and electrolytic cell (2) for 1-3 hours, with the electrolysis current controlled between 7500-9000A;

[0011] S3: The wastewater after electrolysis enters the coagulation sedimentation tank, 5-10 parts of coagulant are added, and coagulation sedimentation is carried out for 2-5 hours.

[0012] Preferably, two baffles are provided in the oil separator, dividing the oil separator into a sediment area, an oil scraping area, and an oil separation area, and an inclined filter screen is provided inside the sediment area.

[0013] Preferably, the electrolytic cell is made of carbon steel lined with nitrile rubber, with dimensions of 0.9-1.2 m×0.9-1.2 m×1.2-1.8 m. The electrolytic cell consists of a reaction tank, a power supply, electrode plates and a water distribution system.

[0014] Preferably, the electrode plates are made of graphite, and there are 16-24 of them in number, arranged in positive and negative poles.

[0015] Preferably, the pH of the electrolytic cell (1) is controlled to be 1-2.

[0016] Preferably, the pH of the electrolytic cell (II) is controlled to be 7-8.

[0017] Preferably, the electrolytic wastewater has high oil content (≥500mg / L), high COD (≥15000mg / L), high chroma, removal rate of 90%-95%, pH = 1-2

[0018] Preferably, the preparation method of the coagulant is:

[0019] S1: Weigh 10-15 parts of TiCl4 and 40-50 parts of Na2CO3 by mass, then add 60-100 parts of thioglycolic acid and 300-400 parts of methanol, heat until no bubbles are generated, cool, and filter to remove methanol to obtain titanium thioglycolate;

[0020] S2: Add 3-8 parts of acrylamide, 0.02-0.6 parts of vinylferrocene, 1-4 parts of sodium methoxide, and 0.02-0.3 parts of a photoinitiator, mix, and perform addition reaction under ultraviolet light. Then, filter, wash with methanol, and dry to obtain a coagulant.

[0021] Preferably, the photoinitiator is a UV series initiator, including one or more of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester, 4-dimethylamino-ethyl benzoate, isopropylthioxanthone, and 1-hydroxycyclohexylphenyl ketone.

[0022] Preferably, the amount of the photoinitiator added is 0.08-0.5 wt % of acrylamide.

[0023] Preferably, the ultraviolet light is: irradiance: 4000-5000 μW / cm 2 , wavelength: 350~360nm, illumination time: 0.6~2h.

[0024] The technical innovation of the present invention lies in that the titanium thioglycolate, acrylamide and vinyl ferrocene undergo a thiol addition reaction to obtain a titanium / ferrocene-doped novel coagulant, which has a significant coagulant effect on coal gasification wastewater with complex water components, high pollutant concentrations, and difficulty in biochemical degradation, and contains a large amount of organic pollutants such as phenols, biphenyls, pyridine, indole and quinoline in the wastewater.

[0025] The implementation of the present invention has the following beneficial effects: compared with the prior art, the coagulant prepared by the present invention generates flocs at a fast speed and with a large particle size when treating coal gasification wastewater, and the structure of the formed flocs is denser; Ti-O-Fe bonds are formed in the coagulant prepared by the present invention, and the internal clusters are compact, presenting a petal-like structure with spatial three-dimensional wrinkles, which can effectively enhance the adsorption bridging and net-catching and sweeping effects of the coagulant; the electrical neutralization and adsorption bridging of the polyhydroxy titanium-iron polymer produced by the coagulant prepared by the present invention play a key role in the coagulation process, and the polyhydroxy titanium-iron polymer produced by the hydrolysis of the coagulant plays a key role in adsorption and complexation; the operating cost of the present invention is low and the treatment efficiency is high DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to embodiments.

[0027] Coagulation experiments were conducted using a six-axis mixer (MY3000-6D). One liter of coal gasification wastewater was added to each beaker and stirred rapidly at 200 rpm for 30 seconds. A certain amount of coagulant was then added and stirred rapidly for 1.5 minutes. The mixture was then stirred slowly at 40 rpm for 15 minutes. After settling for 30 minutes, the supernatant was collected and directly tested.

[0028] Turbidity determination method GB13200-91;

[0029] Determination of suspended matter method GB11901-89;

[0030] COD determination method GB11914-89;

[0031] Ammonia nitrogen determination method GB7479-87;

[0032] Total nitrogen determination method GB11984-89;

[0033] Total phosphorus determination method GB11893-89;

[0034] Cyanide determination method GB7487-87.

[0035] Example 1

[0036] A coal gasification wastewater deoiling and decolorization pretreatment system, the operating steps of which are as follows:

[0037] S1: Take 160g of coal gasification wastewater and pass it through a grease trap to remove most of the oil;

[0038] S2: Then pass through electrolytic cell (1) and electrolytic cell (2), electrolyze for 1 hour, and the electrolysis current is controlled at 9000A;

[0039] S3: The wastewater after electrolysis enters the coagulation sedimentation tank, 5g of coagulant is added, and coagulation and sedimentation are carried out.

[0040] Two baffles are arranged in the oil separator, which divide the oil separator into a sediment area, an oil scraping area and an oil separation area. A filter screen arranged obliquely is arranged inside the sediment area.

[0041] The electrolytic cell is made of carbon steel lined with nitrile rubber and has a size of 1m×1m×1.5m. The electrolytic cell consists of a reaction tank, a power supply, electrode plates and a water distribution system.

[0042] The electrode plates are made of graphite, and there are 16 of them, arranged in positive and negative poles.

[0043] The pH of the electrolytic cell (1) is controlled to be 1.

[0044] The pH of the electrolytic cell (2) is controlled to be 7.

[0045] The coagulation sedimentation time is 2h.

[0046] The preparation method of the coagulant is:

[0047] S1: Weigh 10g TiCl4 and 40g Na2CO3, add 60g thioglycolic acid and 300g methanol, heat until no bubbles are generated, cool, filter and remove methanol to obtain titanium thioglycolate;

[0048] S2: Add 3 g of acrylamide, 0.02 g of vinylferrocene, 1 g of sodium methoxide, and 0.02 g of photoinitiator, mix, and react under ultraviolet light. Then, filter, wash with methanol, and dry to obtain a coagulant.

[0049] The photoinitiator is a UV series initiator, which is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0050] The amount of the photoinitiator added is 0.08 wt% of acrylamide.

[0051] The UV light is: irradiance: 4000μW / cm 2 , wavelength: 350nm, illumination time: 0.6h.

[0052] Example 2

[0053] A coal gasification wastewater deoiling and decolorization pretreatment system, the operating steps of which are as follows:

[0054] S1: Take 170g of coal gasification wastewater and pass it through a grease trap to remove most of the oil;

[0055] S2: Then pass through electrolytic cell (1) and electrolytic cell (2), electrolyze for 1 hour, and the electrolysis current is controlled at 8500A;

[0056] S3: The wastewater after electrolysis enters the coagulation sedimentation tank, and 6g of coagulant is added for coagulation and sedimentation.

[0057] Two baffles are arranged in the oil separator, which divide the oil separator into a sediment area, an oil scraping area and an oil separation area. A filter screen arranged obliquely is arranged inside the sediment area.

[0058] The electrolytic cell is made of carbon steel lined with nitrile rubber and has a size of 1m×1m×1.5m. The electrolytic cell consists of a reaction tank, a power supply, electrode plates and a water distribution system.

[0059] The electrode plates are made of graphite, and there are 18 of them, arranged in positive and negative poles.

[0060] The pH of the electrolytic cell (1) is controlled to be 1.

[0061] The pH of the electrolytic cell (2) is controlled to be 7.

[0062] The coagulation sedimentation time is 3 hours.

[0063] The preparation method of the coagulant is:

[0064] S1: Weigh 12g TiCl4, 44g Na2CO3, add 70g thioglycolic acid and 340g methanol, heat until no bubbles are generated, cool, filter and remove methanol to obtain titanium thioglycolate;

[0065] S2: Add 4 g acrylamide, 0.2 g vinylferrocene, 2 g sodium methoxide, and 0.1 g photoinitiator, mix, and react under ultraviolet light. Then, filter, wash with methanol, and dry to obtain a coagulant.

[0066] The photoinitiator is a UV series initiator, which is 2,4,6-trimethylbenzoylphenyl ethyl phosphonate.

[0067] The amount of the photoinitiator added is 0.2 wt% of acrylamide.

[0068] The UV light is: irradiance: 4500μW / cm 2 , wavelength: 350nm, illumination time: 1h.

[0069] Example 3

[0070] A coal gasification wastewater deoiling and decolorization pretreatment system, the operating steps of which are as follows:

[0071] S1: Take 190g of coal gasification wastewater and pass it through a grease trap to remove most of the oil;

[0072] S2: Then pass through electrolytic cell (1) and electrolytic cell (2) for 2 hours, and the electrolysis current is controlled at 8000A;

[0073] S3: The wastewater after electrolysis enters the coagulation sedimentation tank, 9g of coagulant is added, and coagulation and sedimentation are carried out.

[0074] Two baffles are arranged in the oil separator, which divide the oil separator into a sediment area, an oil scraping area and an oil separation area. A filter screen arranged obliquely is arranged inside the sediment area.

[0075] The electrolytic cell is made of carbon steel lined with nitrile rubber and has a size of 1m×1m×1.5m. The electrolytic cell consists of a reaction tank, a power supply, electrode plates and a water distribution system.

[0076] The electrode plates are made of graphite, and there are 22 of them, arranged in positive and negative poles.

[0077] The pH of the electrolytic cell (1) is controlled to be 2.

[0078] The pH of the electrolytic cell (2) is controlled to be 8.

[0079] The coagulation sedimentation time is 4 hours.

[0080] The preparation method of the coagulant is:

[0081] S1: Weigh 14g TiCl4 and 48g Na2CO3, add 90g thioglycolic acid and 380g methanol, and heat until no bubbles are generated. After cooling, filter and remove the methanol to obtain titanium thioglycolate;

[0082] S2: Add 7 g of acrylamide, 0.5 g of vinylferrocene, 3 g of sodium methoxide, and 0.2 g of photoinitiator, mix, and react under ultraviolet light. Then, filter, wash with methanol, and dry to obtain a coagulant.

[0083] The photoinitiator is a UV series initiator, which is 4-dimethylamino-ethyl benzoate.

[0084] The amount of the photoinitiator added is 0.04 wt% of acrylamide.

[0085] The UV light is: irradiance: 4500μW / cm 2 , wavelength: 360nm, illumination time: 1.5h.

[0086] Example 4

[0087] A coal gasification wastewater deoiling and decolorization pretreatment system, the operating steps of which are as follows:

[0088] S1: Take 200g of coal gasification wastewater and pass it through a grease trap to remove most of the oil;

[0089] S2: Then pass through electrolytic cell (1) and electrolytic cell (2) for 3 hours, and the electrolysis current is controlled at 7500A;

[0090] S3: The wastewater after electrolysis enters the coagulation sedimentation tank, 10g of coagulant is added, and coagulation and sedimentation are carried out.

[0091] Two baffles are arranged in the oil separator, which divide the oil separator into a sediment area, an oil scraping area and an oil separation area. A filter screen arranged obliquely is arranged inside the sediment area.

[0092] The electrolytic cell is made of carbon steel lined with nitrile rubber and has a size of 1m×1m×1.5m. The electrolytic cell consists of a reaction tank, a power supply, electrode plates and a water distribution system.

[0093] The electrode plates are made of graphite, and there are 24 of them, arranged in positive and negative poles.

[0094] The pH of the electrolytic cell (1) is controlled to be 2.

[0095] The pH of the electrolytic cell (2) is controlled to be 8.

[0096] The coagulation sedimentation time is 5 hours.

[0097] The preparation method of the coagulant is:

[0098] S1: Weigh 15g TiCl4, 50g Na2CO3, add 100g thioglycolic acid and 400g methanol, heat until no bubbles are generated, cool, filter and remove methanol to obtain titanium thioglycolate;

[0099] S2: Add 8 g of acrylamide, 0.6 g of vinylferrocene, 4 g of sodium methoxide, and 0.3 g of photoinitiator, mix, and react under ultraviolet light. Then, filter, wash with methanol, and dry to obtain a coagulant.

[0100] The photoinitiator is a UV series initiator, which is isopropylthioxanthone.

[0101] The amount of the photoinitiator added is 0.5 wt% of acrylamide.

[0102] The UV light is: irradiance: 5000μW / cm 2 , wavelength: 360nm, illumination time: 2h.

[0103] Comparative Example 1

[0104] A coal gasification wastewater deoiling and decolorization pretreatment system, the operating steps of which are as follows:

[0105] S1: Take 160g of coal gasification wastewater and pass it through a grease trap to remove most of the oil;

[0106] S2: Then pass through electrolytic cell (1) and electrolytic cell (2), electrolyze for 1 hour, and the electrolysis current is controlled at 9000A;

[0107] S3: The wastewater after electrolysis enters the coagulation sedimentation tank for coagulation and sedimentation.

[0108] Two baffles are arranged in the oil separator, which divide the oil separator into a sediment area, an oil scraping area and an oil separation area. A filter screen arranged obliquely is arranged inside the sediment area.

[0109] The electrolytic cell is made of carbon steel lined with nitrile rubber and has a size of 1m×1m×1.5m. The electrolytic cell consists of a reaction tank, a power supply, electrode plates and a water distribution system.

[0110] The electrode plates are made of graphite, and there are 16 of them, arranged in positive and negative polarity.

[0111] The pH of the electrolytic cell (1) is controlled to be 1.

[0112] The pH of the electrolytic cell (2) is controlled to be 7.

[0113] The coagulation sedimentation time is 2h.

[0114] Comparative Example 2

[0115] A coal gasification wastewater deoiling and decolorization pretreatment system, the operating steps of which are as follows:

[0116] S1: Take 160g of coal gasification wastewater and pass it through a grease trap to remove most of the oil;

[0117] S2: Then pass through electrolytic cell (1) and electrolytic cell (2), electrolyze for 1 hour, and the electrolysis current is controlled at 9000A;

[0118] S3: The wastewater after electrolysis enters the coagulation sedimentation tank, 5g of coagulant is added, and coagulation and sedimentation are carried out.

[0119] Two baffles are arranged in the oil separator, which divide the oil separator into a sediment area, an oil scraping area and an oil separation area. A filter screen arranged obliquely is arranged inside the sediment area.

[0120] The electrolytic cell is made of carbon steel lined with nitrile rubber and has a size of 1m×1m×1.5m. The electrolytic cell consists of a reaction tank, a power supply, electrode plates and a water distribution system.

[0121] The electrode plates are made of graphite, and there are 16 of them, arranged in positive and negative polarity.

[0122] The pH of the electrolytic cell (1) is controlled to be 1.

[0123] The pH of the electrolytic cell (2) is controlled to be 7.

[0124] The coagulation sedimentation time is 2h.

[0125] The preparation method of the coagulant is:

[0126] S1: Weigh 40g of Na2CO3, add 60g of thioglycolic acid and 300g of methanol, and heat until no bubbles are generated. After cooling, filter and remove the methanol to obtain titanium thioglycolate;

[0127] S2: Add 3 g of acrylamide, 0.02 g of vinylferrocene, 1 g of sodium methoxide, and 0.02 g of photoinitiator, mix, and react under ultraviolet light. Then, filter, wash with methanol, and dry to obtain a coagulant.

[0128] The photoinitiator is a UV series initiator, which is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0129] The amount of the photoinitiator added is 0.08 wt% of acrylamide.

[0130] The UV light is: irradiance: 4000μW / cm 2 , wavelength: 350nm, illumination time: 0.6h.

[0131] Comparative Example 3

[0132] A coal gasification wastewater deoiling and decolorization pretreatment system, the operating steps of which are as follows:

[0133] S1: Take 160g of coal gasification wastewater and pass it through a grease trap to remove most of the oil;

[0134] S2: Then pass through electrolytic cell (1) and electrolytic cell (2), electrolyze for 1 hour, and the electrolysis current is controlled at 9000A;

[0135] S3: The wastewater after electrolysis enters the coagulation sedimentation tank, 5g of coagulant is added, and coagulation and sedimentation are carried out.

[0136] Two baffles are arranged in the oil separator, which divide the oil separator into a sediment area, an oil scraping area and an oil separation area. A filter screen arranged obliquely is arranged inside the sediment area.

[0137] The electrolytic cell is made of carbon steel lined with nitrile rubber and has a size of 1m×1m×1.5m. The electrolytic cell consists of a reaction tank, a power supply, electrode plates and a water distribution system.

[0138] The electrode plates are made of graphite, and there are 16 of them, arranged in positive and negative polarity.

[0139] The pH of the electrolytic cell (1) is controlled to be 1.

[0140] The pH of the electrolytic cell (2) is controlled to be 7.

[0141] The coagulation sedimentation time is 2h.

[0142] The preparation method of the coagulant is:

[0143] S1: Weigh 10g TiCl4 and 40g Na2CO3, add 60g thioglycolic acid and 300g methanol, heat until no bubbles are generated, cool, filter and remove methanol to obtain titanium thioglycolate;

[0144] S2: Add 3 g of acrylamide, 0.02 g of vinylferrocene, and 1 g of sodium methoxide, mix, and perform addition reaction under ultraviolet light. Then, filter, wash with methanol, and dry to obtain a coagulant.

[0145] The photoinitiator is a UV series initiator, which is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0146] The amount of the photoinitiator added is 0.08 wt% of acrylamide.

[0147] The UV light is: irradiance: 4000μW / cm 2 , wavelength: 350nm, illumination time: 0.6h.

[0148] The test results of the above examples and comparative examples are shown in the following table:

[0149]

[0150] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for pretreatment of coal gasification wastewater for oil removal and decolorization, the operating steps of which are as follows: S1: Take 160-200 parts by mass of coal gasification wastewater and pass it through a grease trap to remove most of the oil; S2: Electrolysis is carried out in electrolytic cell 1 and electrolytic cell 2 for 1-3 hours, and the electrolysis current is controlled between 7500-9000A; S3: The wastewater after electrolysis enters the coagulation sedimentation tank, 5-10 parts of coagulant are added, and coagulation sedimentation is carried out for 2-5 hours; The preparation method of the coagulant is: S1: Weigh 10-15 parts of TiCl4 and 40-50 parts of Na2CO3 by mass, then add 60-100 parts of thioglycolic acid and 300-400 parts of methanol, heat until no bubbles are generated, cool, and filter to remove methanol to obtain titanium thioglycolate; S2: Add 3-8 parts of acrylamide, 0.02-0.6 parts of vinylferrocene, 1-4 parts of sodium methoxide, and 0.02-0.3 parts of a photoinitiator, mix, and react under ultraviolet light, then filter, wash with methanol, and dry to obtain a coagulant; The photoinitiator is a UV series initiator, including one or more of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester, 4-dimethylamino-ethyl benzoate, isopropylthioxanthone, and 1-hydroxycyclohexylphenyl ketone.

2. The method for pretreatment of coal gasification wastewater for oil removal and decolorization according to claim 1, characterized in that: Two baffles are arranged in the oil separator, which divide the oil separator into a sediment area, an oil scraping area and an oil separation area. A filter screen arranged obliquely is arranged inside the sediment area.

3. The method for pretreatment of coal gasification wastewater for oil removal and decolorization according to claim 1, characterized in that: The electrolytic cell is made of carbon steel lined with nitrile rubber, with dimensions of 0.9-1.2m×0.9-1.2m×1.2-1.8m. The electrolytic cell consists of a reaction tank, a power supply, electrode plates and a water distribution system.

4. A method for pretreatment of coal gasification wastewater for oil removal and decolorization according to claim 3, characterized in that: The electrode plates are made of graphite and are arranged in a positive and negative pattern.

5. The method for pretreatment of coal gasification wastewater for oil removal and decolorization according to claim 1, characterized in that: The pH value of the first electrolytic cell is controlled at 1-2, and the pH value of the second electrolytic cell is controlled at 7-8.

6. The method for pretreatment of coal gasification wastewater for oil removal and decolorization according to claim 1, characterized in that: The added amount of the photoinitiator is 0.08-0.5 wt% of acrylamide.

7. The method for pretreatment of coal gasification wastewater for oil removal and decolorization according to claim 1, characterized in that: The ultraviolet light has the following characteristics: irradiance: 4000-5000 μW / cm2, wavelength: 350-360 nm, and illumination time: 0.6-2 h.

Images