A pretreatment method for benzene-containing organic wastewater

Abstract

The present invention belongs to the technical field of water treatment, and particularly relates to a pretreatment method for benzene-containing organic wastewater. In the present invention, the pH value of the feed liquid obtained by mixing benzene-containing organic wastewater, iron-containing sulfide ore and galena is adjusted to acidic. In the acidic solution, O2 undergoes a two-electron reduction reaction on the surface of the iron-containing sulfide ore to generate OH·. H2O is oxidized on the sulfur defects on the surface of the iron-containing sulfide ore, and the Fe 2+ / sulfur intermediate reacts with O2 to also generate OH·. Moreover, the galvanic effect between pyrite and galena is also beneficial to the generation of OH· on the surface of pyrite. The generated OH· can oxidize the benzene-containing organic matter in the wastewater, thereby significantly reducing the content of benzene-containing organic matter in the wastewater.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and particularly relates to a pretreatment method for benzene-containing organic wastewater. Background Art

[0002] Benzene-containing organic compounds, also known as aromatic compounds, generally refer to cyclic compounds with at least one delocalized bond in the molecule. They have stable structures and are not easily decomposed. They are widely used in industries such as chemical engineering, food, medicine, and printing and dyeing, and are raw materials and reaction intermediates for many chemical engineering processes. With the rapid development of industries such as chemical engineering and medicine, benzene-containing wastewater has also become a common type of organic wastewater. Benzene-containing organic compounds have strong toxicity and corrosiveness, etc., which pose great hazards to the survival of animals and plants and human survival. Once discharged into water bodies, it will cause great environmental pollution. Therefore, the treatment and up-to-standard discharge of benzene-containing wastewater are very important. At present, the treatment methods for benzene-containing organic compounds include biodegradation method, adsorption method, extraction method, catalytic oxidation method, etc. Among these treatment methods, the catalytic oxidation method can efficiently remove benzene-containing organic compounds through relatively simple equipment and has attracted the attention of many researchers. Among them, the Fenton oxidation method has been widely used due to its advantages such as fast reaction rate, simple operation, and mild reaction conditions.

[0003] The Fenton reaction is an inorganic chemical reaction. Hydrogen peroxide is efficiently decomposed in the presence of Fe 2+ to generate hydroxyl radicals with strong oxidation ability and high negative electronegativity, which can oxidize and degrade various organic compounds in water, and finally mineralize the organic compounds in the water into small molecule substances. Research shows that the Fenton reaction has a wide range of applications in the treatment of wastewater such as printing and dyeing wastewater, oil-containing wastewater, phenol-containing wastewater, and coking wastewater. However, the OH· generated during the Fenton reaction is very unstable and easily reacts with interfering substances including reactants such as H2O2 and Fe 2+ etc., thus reducing its degradation efficiency. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a pretreatment method for benzene-containing organic wastewater. The pretreatment method provided by the present invention can avoid the interference of H2O2 and Fe 2+ on OH· in the traditional Fenton method, significantly reduce the content of benzene-containing organic compounds in benzene-containing organic wastewater, and reduce the burden on the subsequent water treatment system while improving the degradation efficiency of benzene-containing organic compounds.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a pretreatment method for benzene-containing organic wastewater, comprising the following steps:

[0007] Mix benzene organic wastewater, iron-containing sulfide ore and galena, adjust the pH value of the mixed feed liquid to be < 7, then carry out pretreatment and filtration in sequence to obtain filtrate and filter residue respectively; the filtrate is subjected to water treatment, and the filter residue is reused in the pretreatment process of the benzene organic wastewater after acid washing.

[0008] Preferably, the benzene organic compounds in the benzene organic wastewater include monobenzene compounds or polybenzene aromatic compounds.

[0009] Preferably, the iron-containing sulfide ore includes pyrite and / or chalcopyrite.

[0010] Preferably, the D90 particle size of the iron-containing sulfide ore is < 0.044 mm.

[0011] Preferably, the D90 particle size of the galena is < 0.044 mm.

[0012] Preferably, the mass ratio of the iron-containing sulfide ore to the volume of the benzene organic wastewater is (1 - 20) g:1 L.

[0013] Preferably, the mass ratio of the iron-containing sulfide ore to the galena is 1 - 5:1.

[0014] Preferably, the pretreatment is carried out under stirring; the stirring rate is 100 - 300 rpm.

[0015] Preferably, the pretreatment time is 1 - 5 h.

[0016] Preferably, the number of reuse times is 5 - 8 times.

[0017] The present invention provides a pretreatment method for benzene organic wastewater, comprising the following steps: Mix benzene organic wastewater, iron-containing sulfide ore and galena, adjust the pH value of the mixed feed liquid to be < 7, then carry out pretreatment and filtration in sequence to obtain filtrate and filter residue respectively; the filtrate is subjected to water treatment, and the filter residue is reused in the pretreatment process of the benzene organic wastewater after acid washing. In the present invention, the pH value of the feed liquid obtained by mixing benzene organic wastewater, iron-containing sulfide ore and galena is adjusted to be acidic. In an acidic solution, O2 undergoes a two-electron reduction reaction on the surface of the iron-containing sulfide ore to generate OH·, H2O is oxidized on the sulfur defect on the surface of the iron-containing sulfide ore, and Fe 2+The reaction of sulfur intermediates with O2 can also produce ·OH. Galena has weak electrical conductivity, while sulfide-containing minerals have semiconductor properties. Due to the different electrostatic potentials on the surfaces of the two minerals, electron transfer occurs during the mutual contact and collision of mineral particles, forming a galvanic effect. Generally speaking, when minerals come into contact, the one with a higher electrostatic potential is the cathode and is protected, while the one with a lower electrostatic potential is the anode and is subject to galvanic corrosion. Sulfide-containing minerals have a higher electrostatic potential, and the oxidation of their surfaces is inhibited, while galena has the lowest electrostatic potential, and the oxidation of its surface is enhanced. After the galvanic effect, galena loses electrons on its surface, and sulfide-containing minerals gain electrons on their surfaces. This galvanic effect is conducive to the reduction of O2 on the surface of sulfide-containing minerals, thereby increasing the amount of ·OH generated on the surface of sulfide-containing minerals. ·OH has extremely strong oxidizing ability, which can oxidize and degrade benzene-containing organic compounds, thereby improving the oxidation and degradation efficiency of benzene-containing organic compounds, significantly reducing the content of benzene-containing organic compounds in wastewater, and reducing the burden on the subsequent water treatment system.

[0018] In addition, the iron-containing sulfide ore and galena used in the pretreatment method of benzene-containing organic wastewater provided by the present invention can be separated from the wastewater by filtration and can be reused multiple times after recovery, which can reduce the iron-containing sludge generated by the traditional Fenton method for treating organic wastewater and reduce secondary pollution. The method provided by the present invention is simple to operate, low in cost, and environmentally friendly. Detailed implementation mode

[0019] The present invention provides a pretreatment method for benzene-containing organic wastewater, comprising the following steps:

[0020] Mix benzene-containing organic wastewater, iron-containing sulfide ore, and galena, and after adjusting the pH value of the resulting mixture to be < 7, perform pretreatment and filtration in sequence to obtain a filtrate and a filter residue respectively;

[0021] The filtrate is subjected to water treatment, and the filter residue is reused in the pretreatment process of the benzene-containing organic wastewater after pickling.

[0022] Unless otherwise specified, the present invention has no special requirements for the sources of the raw materials used, and commercially available products well-known to those skilled in the art can be used.

[0023] The present invention mixes benzene-containing organic wastewater, iron-containing sulfide ore, and galena.

[0024] In the present invention, the source of the benzene-containing organic wastewater is preferably the chemical industry, the food industry, or the pharmaceutical industry, more preferably the chemical industry or the pharmaceutical industry. The present invention has no special limitation on the content of benzene-containing organic compounds in the benzene-containing organic wastewater, and benzene-containing organic compounds with any content can be used.

[0025] In the present invention, the iron-containing sulfide ore preferably includes pyrite and / or chalcopyrite; the D90 particle size of the iron-containing sulfide ore is preferably < 0.044 mm.

[0026] In the present invention, the D90 particle size of the galena is preferably < 0.044 mm.

[0027] In the present invention, the mass ratio of the iron-containing sulfide ore to the volume of the benzene organic wastewater is preferably (1 - 20) g: 1 L, more preferably (5 - 10) g: 1 L.

[0028] In the present invention, the mass ratio of the iron-containing sulfide ore to the galena is preferably 1 - 5:1, more preferably 2 - 4:1.

[0029] The present invention has no special limitation on the process of mixing the benzene organic wastewater, the iron-containing sulfide ore and the galena, and it is only necessary to make the materials evenly mixed.

[0030] After the mixing, the present invention adjusts the pH value of the mixed liquid to be < 7.

[0031] In the present invention, the pH value of the mixed liquid is preferably 2 - 5; the reagent used to adjust the pH value of the mixed liquid is preferably a sulfuric acid solution; the mass concentration of the sulfuric acid solution is preferably 10%.

[0032] After adjusting the pH value of the mixed liquid to be < 7, the present invention pre-treats the mixed liquid after adjusting the pH value.

[0033] In the present invention, the pre-treatment is preferably carried out under stirring; the stirring rate is preferably 100 - 300 rpm, more preferably 150 - 300 rpm; the pre-treatment time is preferably 1 - 5 h, more preferably 2 - 3 h; the pre-treatment is preferably carried out at room temperature.

[0034] In an acidic solution, O2 undergoes a two-electron reduction reaction on the surface of the iron-containing sulfide ore to generate OH·, and H2O is oxidized on the sulfur defects on the surface of the iron-containing sulfide ore and Fe 2+The reaction of sulfur intermediates with O2 can also produce OH·. Galena has weak electrical conductivity, while sulfide-containing minerals have semiconductor properties. Due to the different electrostatic potentials on the surfaces of the two minerals, electron transfer occurs during the mutual contact and collision of mineral particles, forming a galvanic effect. Generally speaking, when minerals come into contact, the one with a higher electrostatic potential is the cathode and is protected, while the one with a lower electrostatic potential is the anode and is subject to galvanic corrosion. Sulfide-containing minerals have a higher electrostatic potential, and the oxidation of their surfaces is inhibited, while galena has the lowest electrostatic potential, and the oxidation of its surface is enhanced. After the galvanic effect, galena loses electrons on its surface, and sulfide-containing minerals gain electrons on their surfaces. This galvanic effect is conducive to the reduction of O2 on the surface of sulfide-containing minerals, thereby increasing the amount of OH· generated on the surface of sulfide-containing minerals. OH· has extremely strong oxidation ability, and benzene organic compounds are attacked by OH·, triggering a series of free radical chain reactions. Hydroxyl radicals are continuously consumed and generated during the reaction, promoting the progress of the chain reaction, and benzene organic compounds are oxidized and degraded into inorganic substances such as carbon dioxide and water, thereby improving the oxidation and degradation efficiency of benzene organic compounds, significantly reducing the content of benzene organic compounds in wastewater, and reducing the burden on the subsequent water treatment system.

[0035] After the pretreatment, the present invention filters the pretreated liquid material to obtain a filtrate and a filter residue respectively.

[0036] The primary treatment removal rate of benzene organic compounds in benzene organic wastewater by the pretreatment method provided by the present invention reaches more than 80%, and the secondary treatment removal rate reaches more than 94%.

[0037] The present invention has no special limitation on the filtration process, and a filtration process well-known in the art can be used.

[0038] After obtaining the filtrate, the present invention treats the filtrate for water treatment. The present invention has no special limitation on the water treatment, and it can be selected according to the actual situation.

[0039] After obtaining the filter residue, the present invention pickles the filter residue and then reuses it in the pretreatment process of the benzene organic wastewater. The present invention has no special limitation on the pickling process, and a pickling process well-known in the art can be used. In the present invention, the number of times of reuse is preferably 5 to 8 times, and more preferably 5 times.

[0040] In the traditional Fenton method for treating organic wastewater, H2O2 and an Fe 2+ solution are added, and Fe 2+ cannot be effectively recovered and iron-containing sludge is generated. However, the iron-containing sulfide ore and galena used in the pretreatment method of benzene organic wastewater provided by the present invention can be separated from the wastewater by filtration, and can be reused multiple times after recovery, avoiding the generation of iron-containing sludge. The method provided by the present invention is simple to operate, low in cost and environmentally friendly.

[0041] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention, but they should not be construed as limiting the protection scope of the present invention.

[0042] Example 1

[0043] Pyrite and galena with a D90 particle size < 0.044 mm were added to benzoic acid wastewater at 200 mg / L (the theoretical COD value was 200 mg / L) so that the mass concentration of pyrite in the mixed liquid was 5 g / L and the mass concentration of galena was 2 g / L. The pH value of the mixed liquid was adjusted to 5.0 with 10% sulfuric acid, and it was stirred at 300 rpm at room temperature for 3 h, then filtered to obtain a filtrate and a filter residue respectively. The filtrate was subjected to water treatment, and the filter residue was pickled and reused in the pretreatment process of the benzene organic wastewater for 5 times.

[0044] After detection, the mass concentration of benzoic acid in the filtrate was 41.54 mg / L, and the COD was 73.6 mg / L. After calculation, the removal rate of benzoic acid was 79.23%, and the COD removal rate was 63.2%. After being reused for 5 times, the mass concentration of benzoic acid in the obtained filtrate was 42.74 mg / L, and the COD was 73.96 mg / L. After calculation, the removal rate of benzoic acid could still reach 78.63%, and the COD removal rate was 63.02%.

[0045] Example 2

[0046] Pyrite and galena with a D90 particle size < 0.044 mm were added to benzoic acid wastewater at 600 mg / L (the theoretical COD value was 600 mg / L) so that the mass concentration of pyrite in the mixed liquid was 10 g / L and the mass concentration of galena was 5 g / L. The pH value of the mixed liquid was adjusted to 5.0 with 10% sulfuric acid, and it was stirred at 300 rpm at room temperature for 3 h, then filtered to obtain a filtrate and a filter residue respectively. The filtrate was subjected to water treatment, and the filter residue was pickled and reused in the pretreatment process of the benzene organic wastewater for 5 times.

[0047] After detection, the mass concentration of benzoic acid in the filtrate was 112.62 mg / L, and the COD was 187.8 mg / L. After calculation, the removal rate of benzoic acid was 81.23%, and the COD removal rate was 68.7%. After being reused for 5 times, the mass concentration of benzoic acid in the obtained filtrate was 117.24 mg / L, and the COD was 211.84 mg / L. After calculation, the removal rate of benzoic acid could still reach 80.46%, and the COD removal rate was 64.69%.

[0048] Example 3

[0049] Add chalcopyrite and galena with D90 particle size < 0.044 mm to benzoic acid wastewater at a concentration of 200 mg / L (the theoretical COD value is 200 mg / L), so that the mass concentration of chalcopyrite in the mixed liquor is 5 g / L and the mass concentration of galena is 2 g / L. Adjust the pH value of the mixed liquor to 5.0 with 10% sulfuric acid, stir at 300 rpm for 3 h at room temperature, filter to obtain the filtrate and filter residue respectively. The filtrate is subjected to water treatment, and the filter residue is reused for the pretreatment process of the benzene organic wastewater after pickling, and reused 5 times.

[0050] After detection, the mass concentration of benzoic acid in the filtrate is 36.32 mg / L, and the COD is 62.4 mg / L. After calculation, the removal rate of benzoic acid is 81.84%, and the COD removal rate is 68.8%; after being reused 5 times, the mass concentration of benzoic acid in the obtained filtrate is 37.32 mg / L, and the COD is 62.64 mg / L. After calculation, the removal rate of benzoic acid can still reach 81.34%, and the COD removal rate is 68.68%.

[0051] Example 4

[0052] Add chalcopyrite and galena with D90 particle size < 0.044 mm to benzoic acid wastewater at a concentration of 600 mg / L (the theoretical COD value is 600 mg / L), so that the mass concentration of chalcopyrite in the mixed liquor is 10 g / L and the mass concentration of galena is 5 g / L. Adjust the pH value of the mixed liquor to 5.0 with 10% sulfuric acid, stir at 300 rpm for 3 h at room temperature, filter to obtain the filtrate and filter residue respectively. The filtrate is subjected to water treatment, and the filter residue is reused for the pretreatment process of the benzene organic wastewater after pickling, and reused 5 times.

[0053] After detection, the mass concentration of benzoic acid in the filtrate is 110.88 mg / L, and the COD is 190.8 mg / L. After calculation, the removal rate of benzoic acid is 81.52%, and the COD removal rate is 68.2%; after being reused 5 times, the mass concentration of benzoic acid in the obtained filtrate is 112.74 mg / L, and the COD is 191.88 mg / L. After calculation, the removal rate of benzoic acid can still reach 81.21%, and the COD removal rate is 68.02%.

[0054] Example 5

[0055] Pyrite and galena with a D90 particle size < 0.044 mm were added to toluene wastewater at a concentration of 200 mg / L (the theoretical COD value was 200 mg / L) such that the mass concentration of pyrite in the mixed liquor was 5 g / L and the mass concentration of galena was 2 g / L. The pH value of the mixed liquor was adjusted to 5.0 with 10% sulfuric acid, and the mixture was stirred at 300 rpm for 3 h at room temperature. After filtration, the filtrate and filter cake were obtained separately. The filtrate was subjected to water treatment, and the filter cake was pickled and reused in the pretreatment process of the benzene-containing organic wastewater for 5 times.

[0056] After detection, the mass concentration of toluene in the filtrate was 36.58 mg / L, and the COD was 62.8 mg / L. Calculated, the removal rate of toluene was 81.71%, and the COD removal rate was 68.6%. After 5 times of reuse, the mass concentration of toluene in the obtained filtrate was 37.52 mg / L, and the COD was 63.14 mg / L. Calculated, the removal rate of toluene could still reach 81.24%, and the COD removal rate was 68.43%.

[0057] Example 6

[0058] Pyrite and galena with a D90 particle size < 0.044 mm were added to toluene wastewater at a concentration of 600 mg / L (the theoretical COD value was 600 mg / L) such that the mass concentration of pyrite in the mixed liquor was 10 g / L and the mass concentration of galena was 5 g / L. The pH value of the mixed liquor was adjusted to 5.0 with 10% sulfuric acid, and the mixture was stirred at 300 rpm for 3 h at room temperature. After filtration, the filtrate and filter cake were obtained separately. The filtrate was subjected to water treatment, and the filter cake was pickled and reused in the pretreatment process of the benzene-containing organic wastewater for 5 times.

[0059] After detection, the mass concentration of toluene in the filtrate was 108.96 mg / L, and the COD was 109.8 mg / L. Calculated, the removal rate of toluene was 81.84%, and the COD removal rate was 81.7%. After 5 times of reuse, the mass concentration of toluene in the obtained filtrate was 110.16 mg / L, and the COD was 111.3 mg / L. Calculated, the removal rate of toluene could still reach 81.64%, and the COD removal rate was 81.45%.

[0060] Example 7

[0061] Pyrite and galena with a D90 particle size < 0.044 mm were added to toluene wastewater at a concentration of 200 mg / L (the theoretical COD value was 200 mg / L) such that the mass concentration of pyrite in the mixed liquor was 5 g / L and the mass concentration of galena was 2 g / L. The pH of the mixed liquor was adjusted to 5.0 with 10% sulfuric acid, and the mixture was stirred at 300 rpm for 3 h at room temperature. Filtration was performed to obtain a filtrate and a filter residue respectively. The filtrate was sent to the water treatment system, and the filter residue was reused in the pretreatment process of the benzene-containing organic wastewater after pickling, and reused 5 times.

[0062] After testing, the mass concentration of toluene in the filtrate was 37.32 mg / L, and the COD was 63.6 mg / L. Calculated, the removal rate of toluene was 81.34%, and the COD removal rate was 68.2%; after reusing 5 times, the mass concentration of toluene in the obtained filtrate was 37.96 mg / L, and the COD was 63.98 mg / L. Calculated, the removal rate of toluene could still reach 81.02%, and the COD removal rate was 68.01%.

[0063] Example 8

[0064] Chalcopyrite and galena with a D90 particle size < 0.044 mm were added to toluene wastewater at a concentration of 600 mg / L (the theoretical COD value was 600 mg / L) such that the mass concentration of chalcopyrite in the mixed liquor was 10 g / L and the mass concentration of galena was 5 g / L. The pH of the mixed liquor was adjusted to 5.0 with 10% sulfuric acid, and the mixture was stirred at 300 rpm for 3 h at room temperature. Filtration was performed to obtain a filtrate and a filter residue respectively. The filtrate was sent to the water treatment system, and the filter residue was reused in the pretreatment process of the benzene-containing organic wastewater after pickling, and reused 5 times.

[0065] After testing, the mass concentration of toluene in the filtrate was 111.3 mg / L, and the COD was 111.6 mg / L. Calculated, the removal rate of toluene was 81.45%, and the COD removal rate was 81.4%; after reusing 5 times, the mass concentration of toluene in the obtained filtrate was 113.28 mg / L, and the COD was 113.4 mg / L. Calculated, the removal rate of toluene could still reach 81.12%, and the COD removal rate was 81.1%.

[0066] Example 9

[0067] The filtrate obtained from the pretreatment in Example 4 (i.e., the pretreated benzoic acid wastewater, with the mass concentration of benzoic acid being 110.88 mg / L and the COD being 190.8 mg / L) was subjected to secondary treatment. 5 g / L of chalcopyrite and 2 g / L of galena were added to this solution, and the pH value of the solution was adjusted to 5.0 with 10% sulfuric acid. Stirring was carried out at 300 rpm for 1 h at room temperature, followed by filtration. The mass concentration of benzoic acid in the obtained filtrate was 33.66 mg / L, and the COD was 56.78 mg / L. After calculation, the removal rate of benzoic acid was 69.64%, and the COD removal rate was 70.24%. Considering the two-stage treatment, the total removal rate of benzoic acid could reach 94.4%, and the COD removal rate could reach 90.5%.

[0068] Comparative Example 1

[0069] For benzoic acid wastewater with a benzoic acid content of 200 mg / L (the theoretical COD value is 200 mg / L), when treated by the traditional Fenton method, that is, the dosage of H2O2 was 9.8 mmol / L, the dosage of Fe 2+ was 0.37 mmol / L, and the pH value of the solution was adjusted to 2.0 with 10% sulfuric acid. After reacting for 1 h, the mass concentration of benzoic acid in the obtained benzoic acid wastewater was 55.54 mg / L, and the COD was 87.6 mg / L. After calculation, the removal rate of benzoic acid was 72.23%, and the COD removal rate was 56.2%.

[0070] Comparative Example 2

[0071] For benzoic acid wastewater with a benzoic acid content of 600 mg / L (the theoretical COD value is 600 mg / L), when treated by the traditional Fenton method, that is, the dosage of H2O2 was 12.8 mmol / L, the dosage of Fe 2+ was 0.49 mmol / L, and the pH value of the solution was adjusted to 2.0 with 10% sulfuric acid. After reacting for 1 h, the mass concentration of benzoic acid in the obtained benzoic acid wastewater was 142.62 mg / L, and the COD was 255 mg / L. After calculation, the removal rate of benzoic acid was 76.23%, and the COD removal rate was 57.5%.

[0072] Comparative Example 3

[0073] Pyrite with a D90 particle size < 0.044 mm was added to 200 mg / L of benzoic acid wastewater (the theoretical COD value is 200 mg / L) to make the mass concentration of pyrite in the mixed solution 5 g / L. The pH value of the mixed solution was adjusted to 5.0 with 10% sulfuric acid, and stirring was carried out at 300 rpm for 3 h at room temperature, followed by filtration to obtain the filtrate and the filter residue respectively. The filtrate was subjected to water treatment, and the filter residue was reused after pickling for the pretreatment process of the benzene-containing organic wastewater and reused repeatedly.

[0074] After detection, the mass concentration of benzoic acid in the filtrate is 124.72 mg / L, the COD is 155.16 mg / L, the removal rate of benzoic acid by pretreatment is only 37.64%, and the COD removal rate is 22.42%.

[0075] Comparative Example 4

[0076] Galena with a D90 particle size < 0.044 mm was added to 200 mg / L of benzoic acid wastewater (the theoretical COD value is 200 mg / L) to make the mass concentration of pyrite in the mixed liquor 5 g / L. The pH value of the mixed liquor was adjusted to 5.0 with 10% sulfuric acid, and it was stirred at 300 rpm for 3 h at room temperature, then filtered to obtain the filtrate and filter residue respectively. The filtrate was subjected to water treatment, and the filter residue was reused after pickling for the pretreatment process of the benzene organic wastewater and reused repeatedly.

[0077] After detection, almost no benzoic acid in the filtrate was oxidized.

[0078] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention rather than all embodiments. People can also obtain other embodiments without creative efforts based on these embodiments, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A pretreatment method for benzene-containing organic wastewater, characterized in that It includes the following steps: Mix benzene organic wastewater, iron-containing sulfide ore and galena, adjust the pH value of the obtained mixed feed liquid to be < 7, and then carry out pretreatment and filtration in sequence to obtain a filtrate and a filter residue respectively; Perform water treatment on the filtrate, and after pickling the filter residue, reuse it in the pretreatment process of the benzene organic wastewater; The benzene organic wastewater is toluene wastewater or benzoic acid wastewater; the theoretical COD value of the benzene organic wastewater is 200 - 600 mg / L; The iron-containing sulfide ore includes pyrite and / or chalcopyrite; The mass ratio of the iron-containing sulfide ore to the volume of the benzene organic wastewater is (1 - 20) g: 1 L; The mass ratio of the iron-containing sulfide ore to galena is 1 - 5:

1.

2. The pretreatment method according to claim 1, wherein The D90 particle size of the iron-containing sulfide ore is < 0.044 mm.

3. The pretreatment method according to claim 1, wherein The D90 particle size of the galena is < 0.044 mm.

4. The pretreatment method according to claim 1, wherein The pretreatment is carried out under stirring; the stirring rate is 100 - 300 rpm.

5. The pretreatment method according to claim 1 or 4, characterized in that The time of the pretreatment is 1 - 5 h.

6. The pretreatment method according to claim 1, characterized in that The number of reuse times is 5 - 8 times.