A method and system for treating manganese-containing organic wastewater

Abstract

The application provides a method and system for treating manganese-containing organic wastewater, wherein the method for treating the manganese-containing organic wastewater comprises the following steps: adding a carbonate into the manganese-containing organic wastewater to perform precipitation, and then separating to obtain manganese carbonate mud and a first filtrate; washing and performing first filtration on the manganese carbonate mud to obtain a carbonate mud filter cake and a second filtrate; drying the carbonate mud filter cake and performing first calcination on at least part of the carbonate mud filter cake to obtain a manganese oxide material; uniformly mixing the manganese oxide material with a raw material of a semiconductor material, and then performing second calcination to obtain a composite catalyst; and adding the composite catalyst and hydrogen peroxide into a mixed filtrate of the first filtrate and the second filtrate, and performing a photo-Fenton reaction and a photocatalytic reaction under light. The method for treating the manganese-containing organic wastewater can realize resource recycling of metal manganese in the manganese-containing organic wastewater, and can also realize degradation and removal of a large amount of organic matters in the wastewater.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, and particularly relates to a method for treating manganese-containing organic wastewater. BACKGROUND

[0002] With the rapid development of the pharmaceutical industry in China, the content of manganese in pharmaceutical wastewater is increasing year by year. The COD of the manganese-containing wastewater is 90000-200000 mg / L, the content of manganese element is 30000-80000 mg / L, the concentration of sulfate ions is 50000-100000 mg / L, and the pH is 4-7. A large amount of manganese-containing wastewater discharge will cause environmental pollution, poison aquatic organisms, and ultimately have adverse effects on human health. However, manganese is also a necessary life element for animals and plants, can improve insulin activity, and promote the synthesis of sugar, lipid and protein metabolism enzymes. At the same time, it is also the second most used metal element in the steel industry. Therefore, through effective technical means to recover manganese, not only can reduce environmental pollution, but also can solve the problem of manganese resource shortage, and realize the resource utilization of manganese-containing pharmaceutical wastewater.

[0003] At present, the main methods for treating manganese-containing wastewater include electrolysis, ion exchange and chemical precipitation. The application of electrolysis and ion exchange is affected by high organic matter, and has the problems of low efficiency, complicated operation, easy to cause secondary pollution, narrow application range and the like. The chemical precipitation method is a method for separating and removing heavy metal ions by using a precipitant to generate a difficultly soluble compound. This method is simple to operate, easy to popularize in industry, and has a broad application prospect in the field of heavy metal wastewater treatment and resource recovery. However, the filtered wastewater after manganese recovery has a high content of organic matter and needs further treatment.

[0004] In the wastewater treatment process, a new process needs to be introduced. The photo-Fenton method has a significant treatment effect and is always recognized by people. However, the Fenton method still has some shortcomings, such as the consumption of hydrogen peroxide and other consumables cannot be completely consumed and utilized, and the efficiency is limited.

[0005] Therefore, it is urgent to develop a method for treating manganese-containing organic wastewater, which can not only recover manganese, but also effectively treat organic matter. SUMMARY

[0006] Therefore, one object of the present application is to provide a method for treating manganese-containing organic wastewater, which converts manganese in the organic wastewater into manganese carbonate material by chemical precipitation, and calcines the manganese carbonate material to be used as raw material for preparing a manganese oxide-containing composite catalyst together with raw material of a semiconductor material, and then makes the manganese-removed manganese-containing organic wastewater undergo a photo-Fenton reaction and a photocatalytic reaction under the action of the manganese oxide-containing composite catalyst to remove organic pollutants. The method for treating manganese-containing organic wastewater realizes the resource recycling of metal manganese in the manganese-containing organic wastewater and the degradation and removal of a large amount of organic matter in the wastewater, and has good economic, environmental and social benefits.

[0007] Another object of the present application is to provide a system for treating manganese-containing organic wastewater.

[0008] To achieve the above object, a first aspect of the present application provides a method for treating manganese-containing organic wastewater, comprising:

[0009] adding a carbonate salt to the manganese-containing organic wastewater for precipitation, and then separating to obtain manganese carbonate salt mud and a first filtrate;

[0010] washing and first filtering the manganese carbonate salt mud to obtain a carbonate salt mud filter cake and a second filtrate;

[0011] drying the carbonate salt mud filter cake and at least partially first calcining to obtain an oxide material of manganese;

[0012] mixing the oxide material of manganese with raw material of a semiconductor material and second calcining to obtain a composite catalyst;

[0013] adding the composite catalyst and hydrogen peroxide to a mixed filtrate of the first filtrate and the second filtrate, and performing a photo-Fenton reaction and a photocatalytic reaction under light to remove organic pollutants in the mixed filtrate, and obtaining treated wastewater.

[0014] In some embodiments, the carbonate salt includes but is not limited to at least one of sodium carbonate, potassium carbonate, etc.

[0015] In some embodiments, the manganese in the manganese-containing organic wastewater includes divalent manganese ions, and the molar ratio of carbonate ions in the carbonate salt to divalent manganese ions is 1.0-1.5, including but not limited to 1.0, 1.1, 1.2, 1.3, 1.4 or 1.5, etc.

[0016] In some embodiments, the composition of the manganese-containing organic wastewater includes: COD 90000-200000 mg / L, divalent manganese ions 30000-80000 mg / L, sulfate ions 50000-100000 mg / L, and pH 4-7.

[0017] In some embodiments, the washing reagent is an organic reagent.

[0018] Preferably, the organic reagent includes, but is not limited to, at least one of glycerol, ethanol, ether, acetone, n-hexane, etc.

[0019] In some embodiments, the drying temperature is 50-150℃, including but not limited to 50℃, 75℃, 100℃, 125℃, or 150℃, etc.

[0020] In some embodiments, the first calcination temperature is 300-1200℃, including but not limited to 300℃, 500℃, 700℃, 900℃, 1100℃, or 1200℃, etc.

[0021] In some embodiments, the first calcination time is 3-7h, including but not limited to 3h, 4h, 5h, 6h, or 7h, etc.

[0022] In some embodiments, the manganese oxide material includes but is not limited to at least one of manganese oxide, manganese dioxide, manganese sesquioxide, or manganese trioxide, etc.

[0023] In some embodiments, the semiconductor material includes but is not limited to at least one of titanium dioxide, perovskite, bismuth oxyhalide (BiOX, X = Cl, Br, I, etc.), etc.

[0024] In some embodiments, the raw material of the semiconductor material includes but is not limited to at least one of tetrabutyl titanate, titanium tetrachloride, strontium chloride, lanthanum nitrate, cerium nitrate, iron nitrate, bismuth chloride, bismuth nitrate. Among them, tetrabutyl titanate, titanium tetrachloride, etc. are the raw material of titanium dioxide, tetrabutyl titanate, titanium tetrachloride, strontium chloride, lanthanum nitrate, cerium nitrate, iron nitrate, ammonium oxalate, etc. are the raw material of perovskite, bismuth chloride, bismuth nitrate, etc. are the raw material of bismuth oxyhalide.

[0025] In some embodiments, the amount-of-substance ratio of the manganese oxide material to the semiconductor material is (7-13):(2-4), including but not limited to 7:2, 13:4, 7:4, 13:2, or 10:3, etc. The mass ratio of the manganese oxide material to the semiconductor material in the above range can exhibit high photocatalytic performance; too much manganese oxide material and too little semiconductor material cannot realize the continuous circulation of the Mn ion valence state of the manganese oxide in the composite catalyst, thereby reducing the continuous generation of active substances; too little manganese oxide material and too much semiconductor material cannot effectively catalyze hydrogen peroxide or persulfate to produce active substances for degrading organic pollutants in the mixed filtrate.

[0026] In some embodiments, the second calcination temperature is 400-600℃, including but not limited to 400℃, 450℃, 500℃, 550℃, or 600℃, etc.

[0027] In some embodiments, the second calcination time is 1-5h, including but not limited to 1h, 2h, 3h, 4h or 5h, etc.

[0028] In some embodiments, the mass ratio of the filtrate, the composite catalyst, the hydrogen peroxide and the persulfate is (5000-10000):(30-150):(400-2500):(100-500).

[0029] In other embodiments, the raw materials participating in the photo-Fenton reaction and the photocatalytic reaction also include a persulfate, and at this time, the mass ratio of the filtrate, the composite catalyst, the hydrogen peroxide and the persulfate is (5000-10000):(30-150):(400-2500):(100-500). The mass ratio of the filtrate, the composite catalyst, the hydrogen peroxide and the persulfate within the above range can fully utilize the oxidizing agent to participate in the catalytic degradation reaction; beyond the above range, for example, too much or too little composite catalyst, then the decomposition of hydrogen peroxide and persulfate is too fast or too slow, resulting in a decrease in degradation efficiency; too much or too little hydrogen peroxide, then the degradation performance is reduced, and too much cannot be completely consumed and utilized, which is not economical, or too little cannot fully degrade the organic pollutants in the mixed filtrate; too much or too little persulfate, then the sulfate content in the wastewater exceeds the standard or cannot effectively improve the efficiency of degrading the organic pollutants in the mixed filtrate.

[0030] In some embodiments, the persulfate includes but is not limited to at least one of sodium persulfate, potassium persulfate, etc.

[0031] In some embodiments, the mass content of hydrogen peroxide in the hydrogen peroxide is 15-45%, preferably 30%.

[0032] In some embodiments, the light irradiation condition is achieved by a light source, and the light source includes but is not limited to at least one of a mercury lamp, a sodium lamp, a xenon lamp, a halogen lamp, etc.

[0033] In some embodiments, the energy density of the light irradiation is 200-400W / m 2 , including but not limited to 200W / m 2 , 300W / m 2 or 400W / m 2 , etc.

[0034] In some embodiments, the light irradiation time is 6-10h, including but not limited to 6h, 7h, 8h, 9h or 10h, etc.

[0035] In some embodiments, the organic pollutants include but are not limited to at least one of ethanol, acetic acid, N,N-dimethylformamide, pyridine, pyrimidine, etc.

[0036] In some embodiments, the method for treating manganese-containing organic wastewater further comprises:

[0037] The treated wastewater is subjected to a second filtration to obtain an inactivated composite catalyst and a third filtrate;

[0038] The inactivated composite catalyst is subjected to calcination to restore activity.

[0039] In some embodiments, the method for treating manganese-containing organic wastewater further comprises: discharging or recycling the third filtrate.

[0040] In some embodiments, the calcination temperature is 300-1200℃, including but not limited to 300℃, 500℃, 700℃, 900℃, 1100℃ or 1200℃, etc.

[0041] In some embodiments, the calcination time is 1-3h.

[0042] The method for treating manganese-containing organic wastewater described in the present application is based on the following concept: the inventors found that after manganese-containing organic wastewater is treated by chemical precipitation to recover manganese, the organic matter content in the filtered wastewater is high and needs to be further treated. The treatment effect of the photo-Fenton method is significant, but the consumables such as hydrogen peroxide added cannot be completely consumed and utilized, and the efficiency is limited. Therefore, a catalyst is introduced to improve the utilization rate of consumables and enhance the degradation efficiency. In line with the principles of price economy, manganese-containing wastewater resource utilization (waste utilization) and environmental protection, manganese carbonate materials recovered by chemical precipitation are used to prepare manganese-containing oxide catalysts. At the same time, since an ultraviolet light source is introduced in the process, in order to improve the utilization rate of the light source and the catalytic performance of the catalyst, a Fenton and photocatalysis synergistic method is introduced, a photocatalyst is introduced into the manganese-containing oxide catalyst, a composite catalyst suitable for photo-Fenton reaction and photocatalysis reaction is prepared, and then it is used for the manganese-containing organic wastewater filtrate (i.e. the mixed filtrate of the first filtrate and the second filtrate) treated by chemical precipitation, to remove organic pollutants in the manganese-containing organic wastewater filtrate (i.e. the mixed filtrate of the first filtrate and the second filtrate) through photo-Fenton reaction and photocatalysis reaction, so as to achieve the purpose of purifying manganese-containing organic wastewater by combining chemical precipitation and photo-Fenton reaction + photocatalysis reaction, and realize the purpose of manganese-containing wastewater resource utilization (waste utilization), environmental protection and cost saving. In addition, the composite catalyst used and recovered in wastewater treatment can restore activity by calcination.

[0043] To achieve the above purpose, the second aspect embodiment of the present application proposes a system for treating manganese-containing organic wastewater, comprising:

[0044] a reaction separation unit, which is connected with a raw water storage tank containing manganese-containing organic wastewater and a carbonate storage tank, removes manganese in the manganese-containing organic wastewater by a chemical precipitation method, and obtains manganese carbonate sludge and a first filtrate;

[0045] a purification treatment device, an inlet of which is connected with the reaction separation unit and an organic reagent storage tank for storing an organic reagent, so as to wash the manganese carbonate sludge from the reaction separation unit and perform solid-liquid separation to obtain manganese carbonate sludge filter cake and a second filtrate; and an outlet of which is connected with a material drying tank for drying the manganese carbonate sludge filter cake and a high-temperature heating instrument for obtaining manganese oxide material from the manganese carbonate sludge filter cake by first calcination in sequence;

[0046] a catalyst preparation unit, which is connected with the high-temperature heating instrument and a raw material storage tank of semiconductor material, and is used for synthesizing a composite catalyst from the manganese oxide material and raw semiconductor material from the raw material storage tank of semiconductor material by second calcination;

[0047] a catalytic degradation unit, which is connected with the reaction separation unit, the purification treatment device, the catalyst preparation unit, and a hydrogen peroxide / persulfate preparation room, and is used for causing a mixed filtrate of the first filtrate and the second filtrate to undergo a photo-Fenton reaction and a photocatalytic reaction with the composite catalyst, hydrogen peroxide from the hydrogen peroxide / persulfate preparation room, or hydrogen peroxide and persulfate under illumination from an illumination device, so as to remove organic pollutants in the mixed filtrate.

[0048] In some embodiments, the reaction separation unit comprises a chemical reaction device and a first solid-liquid separation device connected in sequence, the chemical reaction device comprises one of a coagulation tank, a reaction kettle, and the like, and the first solid-liquid separation device comprises one of a sedimentation tank, a separation kettle, a filter press, and the like.

[0049] In some embodiments, the purification treatment device comprises a washing device and a second solid-liquid separation device connected in sequence, the washing device is connected with the reaction separation unit and an organic reagent storage tank for storing an organic reagent at an inlet, an outlet of the washing device is connected with an inlet of the second solid-liquid separation device, and an outlet of the second solid-liquid separation device is connected with an inlet of the material drying tank.

[0050] In some embodiments, the washing device comprises one of a sprayer, a washing kettle, and the like, and the solid-liquid separation device comprises one of a suction filtration device, a centrifuge, a filter, and the like.

[0051] In some embodiments, the organic reagent comprises at least one of glycerol, ethanol, ether, acetone, n-hexane, and the like.

[0052] In some embodiments, the material drying oven includes, but is not limited to, one of a constant temperature drying oven, a vacuum drying oven, and a blast drying oven.

[0053] In some embodiments, the high-temperature heating instrument includes, but is not limited to, one of a tube furnace, a rotary kiln, and the like.

[0054] In some embodiments, the catalyst preparation unit includes, but is not limited to, one of a catalyst synthesis room, a second calcination device, and the like. When the catalyst preparation unit is a catalyst synthesis room, the catalyst synthesis room is provided with a second calcination device. The second calcination device includes, but is not limited to, one of a tube furnace, a rotary kiln, and the like.

[0055] In some embodiments, the catalytic degradation unit includes, but is not limited to, a reaction tank, a reaction kettle, and the like.

[0056] In some embodiments, the light device includes, but is not limited to, at least one of a mercury lamp, a sodium lamp, a xenon lamp, a halogen lamp, and the like.

[0057] Preferably, the system for treating manganese-containing organic wastewater of the present application further includes a calcination unit connected to the catalytic degradation unit, for recovering the activity of the spent composite catalyst discharged from the catalytic degradation unit by calcination.

[0058] In some embodiments, the calcination unit includes, but is not limited to, one of a tube furnace, a rotary kiln, and the like.

[0059] It should be noted that the system for treating manganese-containing organic wastewater of the present application can be used for the method for treating manganese-containing organic wastewater of the present application, but the preparation system of the method for treating manganese-containing organic wastewater of the present application is not limited to the system for treating manganese-containing organic wastewater of the present application, and any system that can realize the method for treating manganese-containing organic wastewater of the present application can be used for the method for treating manganese-containing organic wastewater of the present application.

[0060] In addition, in the method for treating manganese-containing organic wastewater of the present application, the raw materials such as hydrogen peroxide and persulfate can also be commercially available products.

[0061] The method for treating manganese-containing organic wastewater of the present application can at least bring the following beneficial effects:

[0062] 1. The manganese in the organic wastewater is converted into manganese carbonate material by chemical precipitation method, and after calcination, it is used as raw material together with the raw material of semiconductor material to prepare manganese oxide-containing composite catalyst, and then under the action of manganese oxide-containing composite catalyst, the manganese-containing organic wastewater (i.e. the mixed filtrate) is subjected to photo-Fenton reaction and photocatalytic reaction to remove organic pollutants. The method for treating manganese-containing organic wastewater realizes the resource recycling of metal manganese in manganese-containing organic wastewater, and realizes the degradation and removal of a large amount of organic matter in wastewater, which has good economic benefit, environmental benefit and social benefit.

[0063] 2. The manganese oxide-containing composite catalyst used and recovered in wastewater treatment can be recovered by calcination.

[0064] The additional aspects and advantages of the present application will be partially given in the following description, partially become obvious from the following description, or be known by the practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0065] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

[0066] Figure 1 The process flow chart (i.e. system diagram for treating manganese-containing organic wastewater) for treating manganese-containing organic wastewater shown in an exemplary embodiment of the present application

[0067] Figure 2 The X-ray diffraction (XRD) spectrum of manganese carbonate in Example 1 and standard card PDF#86-0172.

[0068] Figure 3 The scanning electron microscope (SEM) image of manganese carbonate in Example 1.

[0069] Figure 4 The photo of the black oxide obtained after 1000℃ calcination of manganese carbonate in Example 1.

[0070] Figure 5 The X-ray diffraction (XRD) spectrum of the black oxide obtained after 1000℃ calcination in Example 1.

[0071] Figure 6 The scanning electron microscope (SEM) image of the manganese trioxide / titanium dioxide composite catalyst prepared in Example 1.

[0072] Figure 7 The scanning electron microscope (SEM) image of the manganese trioxide / strontium titanate composite catalyst prepared in Example 8.

[0073] REFERENCE NUMERALS:

[0074] 1 - raw water storage tank; 2 - reaction separation unit; 3 - carbonate storage tank; 4 - purification treatment device; 5 - organic reagent storage box; 6 - material drying box; 7 - high-temperature heating instrument; 8 - catalyst preparation unit; 9 - catalytic degradation unit; 10 - hydrogen peroxide / peroxysulfate preparation room. DETAILED DESCRIPTION

[0075] Embodiments of the present application are described in detail below with reference to examples shown in the accompanying drawings. The embodiments described below by reference to the accompanying drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0076] In the application, the disclosure of a numerical range includes all values within the range and the disclosure of further subdivided ranges, including the endpoints and subranges given for these ranges.

[0077] In the application, the raw materials, equipment, etc. involved, if not specially stated, are raw materials, equipment that can be made by commercial means or known methods; the methods involved, if not specially stated, are conventional methods.

[0078] A system for treating manganese-containing organic wastewater and a method for treating manganese-containing organic wastewater are described below with reference to the accompanying drawings.

[0079] As shown in Figure 1 The system for treating manganese-containing organic wastewater of the embodiments of the present application includes a raw water storage tank 1 containing manganese-containing organic wastewater, a reaction separation unit 2, a carbonate storage tank 3 containing a carbonate solution, a purification treatment device 4, an organic reagent storage box 5 for storing organic reagents, a material drying box 6, a high-temperature heating instrument 7, a catalyst preparation unit 8, a catalytic degradation unit 9, and a hydrogen peroxide / peroxysulfate preparation room 10. Among them:

[0080] In some embodiments, the manganese in the manganese-containing organic wastewater includes divalent manganese ions.

[0081] As an optional example, the composition of the manganese-containing organic wastewater includes: COD 90000-200000 mg / L, divalent manganese ions 30000-80000 mg / L, sulfate ions 50000-100000 mg / L, and pH 4-7.

[0082] The inlet of the reaction separation unit 2 is connected to the outlet of the raw water storage tank 1 and the outlet of the carbonate storage tank 3, and the manganese in the manganese-containing organic wastewater is removed by a chemical precipitation method to obtain manganese carbonate mud and a first filtrate.

[0083] In some embodiments, the reaction separation unit 2 comprises a chemical reaction device and a first solid-liquid separation device connected in sequence, an inlet of the chemical reaction device is connected with an outlet of the raw water storage tank 1 and an outlet of the carbonate storage tank 3, and an outlet of the chemical reaction device is connected with an inlet of the first solid-liquid separation device.

[0084] In some embodiments, the chemical reaction device comprises one of a coagulation tank, a reaction kettle and the like, but is not limited thereto.

[0085] In some embodiments, the first solid-liquid separation device comprises one of a sedimentation tank, a liquid separation kettle, a filter press and the like, but is not limited thereto.

[0086] In some embodiments, the carbonate comprises at least one of sodium carbonate, potassium carbonate and the like, but is not limited thereto.

[0087] An inlet of the purification treatment device 4 is connected with an outlet of the reaction separation unit 2 and an outlet of the organic reagent storage tank 5, so as to wash the manganese carbonate mud from the reaction separation unit 2 and perform solid-liquid separation to obtain a manganese carbonate mud filter cake and a second filtrate; and an outlet of the purification treatment device 4 is connected with a material drying tank 6 for drying treatment of the manganese carbonate mud filter cake and a high-temperature heating instrument 7 for obtaining an oxide material of manganese from the manganese carbonate mud filter cake through first calcination.

[0088] In some embodiments, the purification treatment device 4 comprises a washing device and a second solid-liquid separation device connected in sequence, an inlet of the washing device is connected with the reaction separation unit 2 and an organic reagent storage tank 5 for storing an organic reagent, an outlet of the washing device is connected with an inlet of the second solid-liquid separation device, and an outlet of the second solid-liquid separation device is connected with an inlet of the material drying tank 6.

[0089] In some embodiments, the washing device comprises one of a sprayer, a washing kettle and the like, and the solid-liquid separation device comprises one of a suction filtration device, a centrifuge, a filter and the like, but is not limited thereto.

[0090] In some embodiments, the organic reagent comprises at least one of glycerol, ethanol, ether, acetone, n-hexane and the like, but is not limited thereto.

[0091] In some embodiments, the material drying tank 6 comprises one of a constant-temperature drying tank, a vacuum drying tank and a blast drying tank, but is not limited thereto.

[0092] In some embodiments, the high-temperature heating instrument 7 comprises one of a tubular furnace, a rotary kiln and the like, but is not limited thereto.

[0093] The catalyst preparation unit 8 is connected with the high-temperature heating instrument 7 and a semiconductor material raw material storage tank for storing a semiconductor material raw material, and is used for synthesizing a composite catalyst through second calcination of the oxide material of manganese and the semiconductor material raw material from the semiconductor material raw material storage tank.

[0094] In some embodiments, the catalyst preparation unit 8 includes, but is not limited to, one of a catalyst synthesis room, a second calcination device, and the like. When the catalyst preparation unit is a catalyst synthesis room, the catalyst synthesis room is provided with a second calcination device. The second calcination device includes, but is not limited to, one of a tube furnace, a rotary kiln, and the like.

[0095] The catalytic degradation unit 9 is connected to the reaction separation unit 2, the purification treatment device 4, the catalyst preparation unit 8, and the hydrogen peroxide / persulfate preparation room 10, and is used to cause the mixed filtrate of the first filtrate and the second filtrate to undergo a photo-Fenton reaction and a photocatalytic reaction under the illumination condition from the illumination device, with the composite catalyst, the hydrogen peroxide from the hydrogen peroxide / persulfate preparation room 10, or the hydrogen peroxide and the persulfate, so as to remove the organic pollutant in the mixed filtrate.

[0096] In some embodiments, the catalytic degradation unit 9 includes, but is not limited to, a reaction tank, a reaction kettle, and the like.

[0097] In some embodiments, the illumination device includes, but is not limited to, at least one of a mercury lamp, a sodium lamp, a xenon lamp, a halogen lamp, and the like.

[0098] It should be noted that the illumination device can be arranged in, on, or above the catalytic degradation unit.

[0099] In some embodiments, the system for treating manganese-containing organic wastewater according to the embodiments of the present application further includes a calcination unit connected to the catalytic degradation unit, and used to restore the activity of the exhausted composite catalyst discharged from the catalytic degradation unit by calcination.

[0100] In some embodiments, the calcination unit includes, but is not limited to, one of a tube furnace, a rotary kiln, and the like.

[0101] It should be noted that the system for treating manganese-containing organic wastewater according to the present application can be used in the method for treating manganese-containing organic wastewater according to the present application, but the preparation system of the method for treating manganese-containing organic wastewater according to the present application is not limited to the system for treating manganese-containing organic wastewater according to the present application, and any system that can realize the method for treating manganese-containing organic wastewater according to the present application can be used in the method for treating manganese-containing organic wastewater according to the present application.

[0102] In addition, in the method for treating manganese-containing organic wastewater according to the present application, the raw materials such as hydrogen peroxide and persulfate can also be commercially available products.

[0103] The working method of the system for treating manganese-containing organic wastewater according to the embodiments of the present application, i.e., the method for treating manganese-containing organic wastewater according to the embodiments of the present application, includes the following steps:

[0104] S101, adding a carbonate salt to the manganese-containing organic wastewater for precipitation, and then separating to obtain a manganese carbonate salt mud and a first filtrate.

[0105] S102, washing and first filtering the manganese carbonate salt mud to obtain a carbonate mud filter cake and a second filtrate;

[0106] S103, drying the carbonate mud filter cake and then performing a first calcination on at least a portion of the cake to obtain a manganese oxide material.

[0107] S104, mixing the manganese oxide material and the raw material of the semiconductor material and then performing a second calcination to obtain a composite catalyst.

[0108] S105. Add a composite catalyst, hydrogen peroxide or hydrogen peroxide and persulfate to the mixed filtrate of the first filtrate and the second filtrate, carry out a photo-Fenton reaction and a photocatalytic reaction under light conditions, remove organic pollutants in the mixed filtrate, and obtain treated wastewater.

[0109] When the system for treating manganese-containing organic wastewater in the embodiment of the present application also includes a burning unit, the working method of the system for treating manganese-containing organic wastewater in the embodiment of the present application, that is, the method for treating manganese-containing organic wastewater in the embodiment of the present application, also includes: subjecting the treated wastewater to a second filtration to obtain an invalid composite catalyst and a third filtrate, and then burning the invalid composite catalyst to restore its activity, and discharging or recycling the third filtrate.

[0110] It should be noted that, in some cases, either the burning of the spent composite catalyst or the discharge or recycling of the filtrate can be performed; in other cases, both the burning of the spent composite catalyst and the discharge or recycling of the filtrate can be performed.

[0111] Certain features of the present technology are further illustrated in the following non-limiting examples.

[0112] Example 1

[0113] (System for treating manganese-containing organic wastewater)

[0114] like Figure 1 As shown, the system for treating manganese-containing organic wastewater in this embodiment includes a raw water storage tank 1 containing manganese-containing organic wastewater, a reaction separation unit 2, a carbonate storage tank 3 containing potassium carbonate, a purification treatment device 4, an organic reagent storage box 5 for storing organic reagents, a material drying box 6, a high-temperature heating device 7, a catalyst preparation unit 8, a catalytic degradation unit 9, and a hydrogen peroxide / persulfate preparation room 10. Among them:

[0115] The reaction separation unit 2 comprises a chemical reaction device and a first solid-liquid separation device connected in sequence, the inlet of the chemical reaction device is connected with the outlet of the raw water storage tank 1 and the outlet of the carbonate storage tank 3, and the manganese in the manganese-containing organic wastewater is removed by a chemical precipitation method. The outlet of the chemical reaction device is connected with the inlet of the first solid-liquid separation device, so as to perform solid-liquid separation on the product from the chemical reaction device, and obtain manganese carbonate sludge and a first filtrate. The chemical reaction device is a stainless steel reaction kettle, and the first solid-liquid separation device is a filter.

[0116] The purification treatment equipment 4 comprises a washing device and a second solid-liquid separation device connected in sequence, the inlet of the washing device is connected with the solid outlet of the first solid-liquid separation device of the reaction separation unit 2 and the outlet of the organic reagent storage box 5 for storing the organic reagent, so as to wash the manganese carbonate sludge from the solid-liquid separation of the first solid-liquid separation device by using the organic solvent. The outlet of the washing device is connected with the inlet of the second solid-liquid separation device, so as to perform solid-liquid separation on the manganese carbonate sludge to obtain carbonate sludge cake and a second filtrate. The washing device is a spray washing machine, and the second solid-liquid separation device is a commercially available vacuum filtration device (for example, a vacuum filter). The organic solvent is a mixture of ethanol and water, and the mass content of ethanol is 10%.

[0117] The inlet of the material drying box 6 is connected with the solid outlet of the second solid-liquid separation device, for drying the manganese carbonate sludge cake from the second solid-liquid separation device. The material drying box 6 is a constant-temperature drying box.

[0118] The inlet of the high-temperature heating instrument 7 is connected with the outlet of the material drying box 6, for obtaining the oxide material of manganese from the dried manganese carbonate sludge cake through first calcination. The high-temperature heating instrument 7 is a tubular furnace.

[0119] The catalyst preparation unit 8 comprises a catalyst synthesis room, and a second calcination device is arranged in the catalyst synthesis room. The inlet of the second calcination device is connected with the outlet of the high-temperature heating instrument 7 and the outlet of a semiconductor material raw material storage tank for storing the raw material of the semiconductor material, for synthesizing a composite catalyst from the oxide material of manganese and the raw material of the semiconductor material from the semiconductor material raw material storage tank through second calcination. The second calcination device is a tubular furnace, and the raw material of the semiconductor material is tetrabutyl titanate.

[0120] The catalytic degradation unit 9 is connected with the filtrate outlet of the first solid-liquid separation device of the reaction separation unit 2, the filtrate outlet of the second solid-liquid separation device of the purification treatment equipment 4, the second calcination equipment outlet of the catalyst preparation unit 8 and the hydrogen peroxide outlet of the hydrogen peroxide / peroxysulfate preparation room 10, for mixing the first filtrate and the second filtrate to carry out the photo-Fenton reaction and the photocatalytic reaction under the light irradiation from the light irradiation device with the composite catalyst and the hydrogen peroxide from the hydrogen peroxide / peroxysulfate preparation room 10, so as to remove the organic pollutants in the filtrate. The catalytic degradation unit 9 is a stainless steel reaction kettle. The light irradiation device is a 300w mercury lamp, and the light irradiation device is installed on the catalytic degradation unit 9. The hydrogen peroxide is hydrogen peroxide with a mass content of 30%.

[0121] The method for treating the manganese-containing organic wastewater by using the system for treating the manganese-containing organic wastewater of the embodiment comprises the following steps:

[0122] The method for treating the manganese-containing organic wastewater by using the system for treating the manganese-containing organic wastewater of the embodiment comprises the following steps:

[0123] Step (a): 5L of the manganese-containing organic wastewater (COD is 108000mg / L, the content of the divalent manganese ion is 61400mg / L, the pH is 5.06, and the concentration of the sulfate ion is 73612mg / L) is added into the chemical reaction device of the reaction separation unit, and then the potassium hydroxide with a mass fraction of 50% is added to adjust the pH of the manganese-containing organic wastewater to neutral (pH=7) to obtain a mixed solution. Then, 0.92kg of potassium carbonate solid is added according to the molar ratio of the carbonate to the divalent manganese ion in the mixed solution being 1.2, and the precipitation is carried out for 3h, and then the solid-liquid separation is carried out through the first solid-liquid separation device of the reaction separation unit to obtain the manganese carbonate salt mud and 4.91kg of the first filtrate, and the organic wastewater of the first filtrate flows into the catalytic degradation unit 9.

[0124] Step (b): the manganese carbonate salt mud obtained in step (a) is washed in the washing device of the purification treatment equipment with the ethanol with a mass fraction of 10%, and then the manganese carbonate salt mud is filtered through the second solid-liquid separation device to obtain the manganese carbonate salt mud filter cake and 0.58kg of the second filtrate, and the organic wastewater of the second filtrate flows into the catalytic degradation unit 9.

[0125] Step (c): the manganese carbonate salt mud filter cake obtained in step (b) is placed in the material drying box and dried at 105℃ for 8h to obtain 642g of the relatively pure manganese carbonate powder.

[0126] Step (d): 200g of the manganese carbonate powder obtained in step (c) is placed in the high-temperature heating instrument and calcined at 1000℃ for 5h to obtain the black oxide, that is, the manganese sesquioxide.

[0127] Step (e): 100 g of the trimanganese tetroxide obtained in step (d), 33 g of tetrabutyl titanate and 7 g of water were mixed uniformly, then filtered to obtain a solid, and then the solid was added into the second calcination device of the catalyst preparation unit to prepare a trimanganese tetroxide / titanium dioxide composite catalyst at 500°C for 3 h, obtaining 107.8 g of the trimanganese tetroxide / titanium dioxide composite catalyst.

[0128] Step (f): the manganese-removed organic wastewater filtrate (a mixed filtrate of all the first filtrate and the second filtrate) from the first and second solid-liquid separation devices and 50 g of the trimanganese tetroxide / titanium dioxide composite catalyst obtained in step (e) were placed in the catalytic degradation unit, then 2.2 kg of 30% mass fraction hydrogen peroxide was added, and the above-mentioned organic filtrate was treated by irradiation with a 300 w mercury lamp for 8 h, during which the solution was stirred by a circulating pump, to remove organic pollutants such as ethanol, n-hexane, acetic acid, N,N-dimethylformamide, pyridine, pyrimidine, etc., obtaining the treated wastewater.

[0129] Step (g): the treated wastewater in step (f) was filtered to obtain a third filtrate and the spent trimanganese tetroxide / titanium dioxide composite catalyst, and the third filtrate was discharged or reused.

[0130] Figure 2 The X-ray diffraction (XRD) spectrum of the manganese carbonate in Example 1 is shown in FIG. 1. Figure 2 As can be seen, the measured peaks of the manganese carbonate material generated by the reaction of the divalent manganese ions and the carbonate ions in the wastewater correspond to the peaks of the standard card PDF #86-0172, and there are no other impurity peaks, indicating that the formed manganese carbonate has high purity and crystallinity.

[0131] Figure 3 The scanning electron microscope (SEM) image of the manganese carbonate in Example 1 is shown in FIG. 2. Figure 3 As can be seen, the formed manganese carbonate material presents irregular spherical large particles, which is beneficial to filtration and recovery.

[0132] Figure 5 The X-ray diffraction (XRD) spectrum of the black oxide obtained after calcination at 1000°C in Example 1 is shown in FIG. 3. Figure 5 As can be seen, the diffraction characteristic peaks of the black oxide obtained after calcination at 1000°C are consistent with the diffraction characteristic peaks of trimanganese tetroxide, indicating that the manganese carbonate material forms a trimanganese tetroxide material under the action of high temperature.

[0133] Figure 6 The scanning electron microscope (SEM) image of the trimanganese tetroxide / titanium dioxide composite catalyst prepared in Example 1 is shown in FIG. 4. Figure 6 As can be seen, the titanium dioxide material is successfully loaded on the trimanganese tetroxide and agglomerates on the trimanganese tetroxide.

[0134] Example 2

[0135] This example is basically the same as Example 1, except that:

[0136] In the system for treating manganese-containing organic wastewater of this example, the method for treating manganese-containing organic wastewater, the spent trimanganese tetroxide / titanium dioxide composite catalyst in step (g) is calcined at 1000°C for 2h to obtain a trimanganese tetroxide / titanium dioxide composite catalyst with restored activity; then the trimanganese tetroxide / titanium dioxide composite catalyst with restored activity is used in step (f), which is:

[0137] The manganese-removed organic wastewater filtrate (mixed filtrate of all the above-mentioned first filtrate and second filtrate) from the first and second solid-liquid separation devices and 50g of the trimanganese tetroxide / titanium dioxide composite catalyst with restored activity are placed in the catalytic degradation unit, then 2.3kg of 30% mass fraction hydrogen peroxide is added, and 300w mercury lamp irradiation is performed for 8h, during which the circulating pump is used to stir the solution, so as to treat the above-mentioned manganese-removed organic wastewater filtrate to remove organic pollutants such as ethanol, n-hexane, acetic acid, N,N-dimethylformamide, pyridine, and pyrimidine, and obtain the treated wastewater.

[0138] Example 3 (comparative example 1, containing persulfate)

[0139] This example is basically the same as Example 1, except that:

[0140] In the system for treating manganese-containing organic wastewater of this example, the method for treating manganese-containing organic wastewater, step (f) includes, in addition to the 50g of trimanganese tetroxide / titanium dioxide composite catalyst obtained in step (e) and 2.2kg of 30% mass fraction hydrogen peroxide, 0.2kg of potassium persulfate is also added into the catalytic degradation unit.

[0141] Example 4 (lower limit of manganese-containing organic wastewater indicators)

[0142] This example is basically the same as Example 1, except that:

[0143] The composition of the manganese-containing organic wastewater is: COD is 90000mg / L, divalent manganese ion content is 30000mg / L, pH is 4, and sulfate ion concentration is 30000mg / L.

[0144] The system for treating manganese-containing organic wastewater of the present embodiment treats the manganese-containing organic wastewater by the following method. In step (a), 5 L of manganese-containing organic wastewater (COD: 90,000 mg / L, divalent manganese ion content: 30,000 mg / L, pH: 4, sulfate ion concentration: 30,000 mg / L) is placed in a chemical reaction device of a reaction-separation unit, and 50% by mass of potassium hydroxide is added to adjust the pH of the manganese-containing organic wastewater to neutral (pH = 7) to obtain a mixed solution. Then, 0.46 kg of solid potassium carbonate is added to the mixed solution in a molar ratio of carbonate to divalent manganese ions of 1.2, and precipitation is performed for 3 h, followed by solid-liquid separation by a first solid-liquid separation device of the reaction-separation unit to obtain manganese carbonate sludge and 4.95 kg of a first filtrate, and the organic wastewater of the first filtrate is flowed into a catalytic degradation unit 9.

[0145] In step (b), the manganese carbonate sludge obtained in step (a) is washed with 10% by mass of ethanol in a washing device of a purification treatment apparatus, and then filtered by a second solid-liquid separation device to obtain a manganese carbonate sludge cake and 0.35 kg of a second filtrate, and the organic wastewater of the second filtrate is flowed into the catalytic degradation unit 9.

[0146] In step (c), the manganese carbonate sludge cake obtained in step (b) is dried at 105°C for 8 h in a material drying oven to obtain 310 g of relatively pure manganese carbonate powder.

[0147] In step (f), the manganese-removed organic wastewater filtrate (mixed filtrate of all the first filtrate and the second filtrate described above) from the first solid-liquid separation device and the second solid-liquid separation device and 50 g of the manganese sesquioxide / titanium dioxide composite catalyst obtained in step (e) are placed in the catalytic degradation unit, and then 1.8 kg of 30% by mass of hydrogen peroxide is added, and 300 W of a mercury lamp is irradiated for 7 h, and a circulating pump is used to stir the solution during the irradiation, and the manganese-removed organic wastewater filtrate is treated to remove organic contaminants such as ethanol, n-hexane, acetic acid, N,N-dimethylformamide, pyridine, and pyrimidine to obtain treated wastewater.

[0148] Example 5 (comparative example 4 containing persulfate)

[0149] The present embodiment is basically the same as Example 4, except that:

[0150] In the method for treating manganese-containing organic wastewater of the system for treating manganese-containing organic wastewater of the present embodiment, 0.17 kg of potassium persulfate is added to the catalytic degradation unit in addition to the 50 g of the manganese sesquioxide / titanium dioxide composite catalyst obtained in step (e) and the 1.8 kg of 30% by mass of hydrogen peroxide.

[0151] Example 6 (upper limit of manganese-containing organic wastewater indicators)

[0152] This example is basically the same as Example 1, except that:

[0153] The composition of the manganese-containing organic wastewater is: COD 200000 mg / L, divalent manganese ion content 80000 mg / L, pH 7, sulfate ion concentration 100000 mg / L.

[0154] In the system for treating manganese-containing organic wastewater of this example, in step (a), 5 L of manganese-containing organic wastewater (COD 200000 mg / L, divalent manganese ion content 80000 mg / L, pH 7, sulfate ion concentration 100000 mg / L) is added to the chemical reaction device of the reaction separation unit, and 50% by mass of potassium hydroxide is added to adjust the pH of the manganese-containing organic wastewater to neutral (pH = 7) to obtain a mixed solution. Then, 1 kg of solid potassium carbonate is added according to a molar ratio of carbonates to divalent manganese ions in the mixed solution of 1.5, and precipitation is carried out for 3 h, and then solid-liquid separation is carried out by the first solid-liquid separation device of the reaction separation unit to obtain manganese carbonate salt mud and 5.17 kg of first filtrate, and the organic wastewater of the first filtrate flows into the catalytic degradation unit 9.

[0155] In step (b), the manganese carbonate salt mud obtained in step (a) is washed with 15% by mass of ethanol in the washing device of the purification treatment equipment, and then the manganese carbonate salt mud is filtered through the second solid-liquid separation device to obtain manganese carbonate salt mud filter cake and 0.92 kg of second filtrate, and the organic wastewater of the second filtrate flows into the catalytic degradation unit 9.

[0156] In step (c), the manganese carbonate salt mud filter cake obtained in step (b) is placed in a material drying oven and dried at 105°C for 8 h to obtain 832 g of relatively pure manganese carbonate powder.

[0157] In step (f), the manganese-removed organic wastewater filtrate (mixed filtrate of all the first filtrate and the second filtrate described above) from the first solid-liquid separation device and the second solid-liquid separation device and 100 g of the manganese trioxide / titanium dioxide composite catalyst obtained in step (e) are placed in the catalytic degradation unit, and then 4.0 kg of 30% by mass of hydrogen peroxide is added, and a 500w mercury lamp is irradiated for 8 h, and a circulating pump is used to stir the solution during the irradiation, so that the manganese-removed organic wastewater filtrate is treated to remove organic pollutants such as ethanol, n-hexane, acetic acid, N,N-dimethylformamide, pyridine, and pyrimidine, and treated wastewater is obtained.

[0158] Example 7 (comparing example 6 containing persulfate)

[0159] This example is basically the same as Example 6, except that:

[0160] The system for treating manganese-containing organic wastewater of the present embodiment is used to treat manganese-containing organic wastewater by the method for treating manganese-containing organic wastewater, wherein step (f) of adding the catalyst degradation unit further comprises 0.4 kg of potassium persulfate in addition to 100 g of the manganese tetroxide / titanium dioxide composite catalyst obtained in step (e) and 4.0 kg of 30% mass fraction hydrogen peroxide.

[0161] Example 8 (manganese oxide and semiconductor material are different in the composite catalyst for photo-Fenton and photocatalytic reactions, and the semiconductor material is perovskite)

[0162] The present embodiment is basically the same as Example 1, except that:

[0163] The system for treating manganese-containing organic wastewater of the present embodiment is used to treat manganese-containing organic wastewater by the method for treating manganese-containing organic wastewater, wherein:

[0164] Step (e): 100 g of manganese tetroxide, 33 g of tetrabutyl titanate, 35.5 g of strontium chloride hexahydrate, 9.2 g of ammonium oxalate, and 30 g of water are uniformly mixed, then filtered to obtain a solid, and then the solid is added to the second calcination device of the catalyst preparation unit to prepare 117.8 g of manganese tetroxide / strontium titanate composite catalyst by calcination at 800°C for 5 h.

[0165] Step (f): the manganese-removed organic wastewater filtrate (mixed filtrate of all the first filtrate and the second filtrate) from the first and second solid-liquid separation devices and 50 g of the manganese tetroxide / strontium titanate composite catalyst obtained in step (e) are placed in the catalyst degradation unit, then 2.2 kg of 30% mass fraction hydrogen peroxide is added, and a 300 w mercury lamp is irradiated for 8 h, during which the solution is stirred by a circulating pump, to treat the manganese-removed organic wastewater filtrate to remove organic pollutants such as ethanol, n-hexane, acetic acid, N,N-dimethylformamide, pyridine, and pyrimidine, thereby obtaining treated wastewater.

[0166] Step (g): the treated wastewater in step (f) is filtered to obtain a third filtrate and spent manganese tetroxide / strontium titanate composite catalyst, and the third filtrate is discharged or reused.

[0167] Figure 7 A scanning electron microscope (SEM) image of the manganese tetroxide / strontium titanate composite catalyst prepared for Example 8. From the image, it can be seen that the strontium titanate material is successfully loaded on the manganese tetroxide and agglomerates on the manganese tetroxide. Figure 7

[0168] Example 9 (manganese oxide and semiconductor material are different in the composite catalyst for photo-Fenton and photocatalytic reactions, and the semiconductor material is bismuth oxyhalide)

[0169] The present embodiment is basically the same as Example 1, except that: ​

[0170] The system for treating manganese-containing organic wastewater of the present embodiment treats the manganese-containing organic wastewater by the following method:

[0171] Step (e): 100 g of trimanganese tetroxide, 47.1 g of bismuth nitrate pentahydrate, 5 g of citric acid, 5.2 g of ammonium chloride, and 30 g of water were mixed uniformly, and then dried at 105°C for 5 h to obtain a solid; the solid was then added to the second calcination device of the catalyst preparation unit, and calcined at 650°C for 3 h to prepare 125.2 g of trimanganese tetroxide / bismuth oxychloride composite catalyst.

[0172] Step (f): the manganese-removed organic wastewater filtrate from the first and second solid-liquid separation devices (the mixed filtrate of all the above-mentioned first and second filtrates) and 50 g of the trimanganese tetroxide / bismuth oxychloride composite catalyst obtained in step (e) were placed in the catalytic degradation unit, and then 2.2 kg of 30% mass fraction hydrogen peroxide was added, and the solution was stirred by a circulating pump under irradiation of a 300 w mercury lamp for 8 h, so that the manganese-removed organic wastewater filtrate was treated to remove organic pollutants such as ethanol, n-hexane, acetic acid, N,N-dimethylformamide, pyridine, and pyrimidine, and treated wastewater was obtained.

[0173] Step (g): the treated wastewater of step (f) was filtered to obtain a third filtrate and spent trimanganese tetroxide / bismuth oxychloride composite catalyst, and the third filtrate was discharged or reused.

[0174] Comparative Example 1 (existing Fenton method)

[0175] The present comparative example is basically the same as Example 1, except that the system for treating manganese-containing organic wastewater of the present comparative example does not include steps (c), (d), and (e), and step (f) is to adjust the pH of the filtrate to 2 using sulfuric acid in the catalytic degradation unit of Example 1, add 1.8 kg of ferrous sulfate heptahydrate and 2.2 kg of 30% mass fraction hydrogen peroxide, and stir the solution by a circulating pump for 8 h, so that the manganese-removed organic wastewater filtrate from the first and second solid-liquid separation devices (the mixed filtrate of the first and second filtrates) is treated to remove organic pollutants such as ethanol, n-hexane, acetic acid, N,N-dimethylformamide, pyridine, and pyrimidine, and treated wastewater is obtained, and the generated iron sludge is simultaneously recovered.

[0176] Comparative Example 2 (existing chemical precipitation method)

[0177] The comparative example is basically the same as example 1, except that the system for treating manganese-containing organic wastewater of the comparative example does not include steps (b), (c), (d), (e), (f), and step (a) is adding potassium hydroxide to the chemical reaction device of the reaction separation unit of example 1 containing 5 L of manganese-containing organic wastewater (COD is 108000 mg / L, divalent manganese ion content is 61400 mg / L, pH is 5.06, and sulfate ion concentration is 73612 mg / L) to adjust the pH of the manganese-containing organic wastewater to neutral (pH = 7) to obtain a mixed solution. Subsequently, 0.76 kg of solid potassium hydroxide is added to precipitate for 3 h according to a ratio of divalent manganese ion concentration to hydroxide in the mixed solution of 1.2, and then solid-liquid separation is performed by the first solid-liquid separation device of the reaction separation unit of example 1 to obtain manganese hydroxide salt mud and first filtrate.

[0178] Comparative example 3 (existing chemical precipitation method + existing Fenton method)

[0179] The comparative example is basically the same as example 1, except that the system for treating manganese-containing organic wastewater of the comparative example does not include steps (b), (c), (d), (e), and step (a) is adding potassium hydroxide to the chemical reaction device of the reaction separation unit of example 1 containing 5 L of manganese-containing organic wastewater (COD is 108000 mg / L, divalent manganese ion content is 61400 mg / L, pH is 5.06, and sulfate ion concentration is 73612 mg / L) to adjust the pH of the manganese-containing organic wastewater to neutral (pH = 7) to obtain a mixed solution. Subsequently, 0.76 kg of solid potassium hydroxide is added to precipitate for 3 h according to a ratio of divalent manganese ion concentration to hydroxide in the mixed solution of 1.2, and then solid-liquid separation is performed by the first solid-liquid separation device of the reaction separation unit of example 1 to obtain manganese hydroxide salt mud and 4.9 kg of first filtrate.

[0180] Step (f) is adjusting the pH of the filtrate to 2 using sulfuric acid in the catalytic degradation unit of example 1, adding 1.5 kg of ferrous sulfate heptahydrate, and 1.8 kg of 30% mass fraction hydrogen peroxide, and circulating the pump to stir the solution for 8 h to treat the manganese-removed organic wastewater filtrate (mixed filtrate of the first filtrate and the second filtrate) from the first solid-liquid separation device and the second solid-liquid separation device to remove organic pollutants such as ethanol, n-hexane, acetic acid, N,N-dimethylformamide, pyridine, and pyrimidine, and obtain treated wastewater.

[0181] The properties of the treated wastewater (third filtrate of the example) of the manganese-containing organic wastewater of each example and comparative example and the manganese recovery rate are tested, and the results are shown in Table 1.

[0182] Wastewater properties and manganese recovery rate after treatment of manganese-containing organic wastewater of each example and comparative example in Table 1

[0183]

[0184] As can be seen from Table 1, the method for treating manganese-containing organic wastewater of the present application can achieve a manganese recovery rate and a better COD removal rate compared with the comparative example, and the wastewater after treatment is neutral, which is conducive to subsequent discharge. Specifically:

[0185] As can be seen from Comparative Example 1 and Comparative Example 1, the method for treating manganese-containing organic wastewater of Example 1 of the present application can improve the COD removal rate by 14.5% compared with the existing Fenton method of Comparative Example 1, and no iron sludge is produced, and the wastewater after treatment is neutral, which is conducive to subsequent discharge. This is because: Example 1 uses heterogeneous catalyst trimanganese tetraoxide / titanium dioxide composite catalyst to catalyze hydrogen peroxide for organic matter degradation, and hydrogen peroxide can be fully utilized under the action of the catalyst, so the COD removal rate is high, which also indirectly shows that the heterogeneous catalyst of the present application can realize catalytic degradation of organic matter. While Comparative Example 1 uses the existing Fenton reaction, which uses divalent iron ions for homogeneous catalysis, and the divalent iron ions are deactivated and cannot continue to catalyze degradation during the catalytic process, resulting in incomplete consumption of hydrogen peroxide and relatively low COD removal rate; at the same time, Comparative Example 1 uses the existing Fenton method to degrade organic matter, which needs to adjust the pH to be acidic, and a large amount of iron sludge will be produced after wastewater treatment.

[0186] As can be seen from Comparative Example 1 and Comparative Example 2, the method for treating manganese-containing organic wastewater of Example 1 of the present application can improve the COD removal rate by 42 times compared with the existing chemical precipitation method of Comparative Example 2, and the removal rate reaches 99.86%; at the same time, the wastewater after treatment is neutral, which is conducive to subsequent discharge. While the existing chemical precipitation method of Comparative Example 2 uses potassium hydroxide to generate manganese hydroxide precipitation to recover divalent manganese ions, but cannot degrade organic matter, and at the same time, due to the addition of a large amount of potassium hydroxide, the solution is alkaline, and the pH needs to be adjusted to neutral before discharge.

[0187] As can be seen from the comparative example 1 and the comparative example 3, the method for treating the manganese-containing organic wastewater in the application example 1 has a COD removal rate increased by 14.5% compared with the combination of the existing chemical precipitation method and the existing Fenton method in the comparative example 3, and no iron sludge is generated, and the wastewater after treatment is neutral, which is beneficial to subsequent discharge; while in the comparative example 3, potassium hydroxide is used to generate manganese hydroxide precipitation, and divalent manganese ions can be recovered, but a large amount of potassium hydroxide is added to make the solution alkaline, and then the Fenton method is used to degrade organic matter, and the pH needs to be adjusted to be acidic. After the wastewater is treated by the Fenton process, on the one hand, the wastewater is acidic, and the pH needs to be adjusted to be neutral before being discharged; on the other hand, a large amount of iron sludge is generated, which is not conducive to subsequent discharge.

[0188] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present description, the illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the different embodiments or examples described in the present description and the features of the different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0189] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0190] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A method of treating manganese-containing organic wastewater, characterized by, The method comprises the following steps: adding carbonate into the manganese-containing organic wastewater to carry out precipitation, and then separating to obtain manganese carbonate mud and a first filtrate; washing the manganese carbonate mud, and then carrying out first filtration to obtain carbonate mud filter cake and a second filtrate; drying the carbonate mud filter cake, and then carrying out first calcination on at least part of the dried carbonate mud filter cake to obtain a manganese oxide material; mixing the manganese oxide material with raw materials of a semiconductor material, and then carrying out second calcination to obtain a composite catalyst; adding the composite catalyst and hydrogen peroxide into the mixed filtrate of the first filtrate and the second filtrate, and then carrying out photo-Fenton reaction and photocatalytic reaction under light irradiation to remove organic pollutants in the mixed filtrate, and thus obtaining treated wastewater; the manganese oxide material comprises trimanganese tetraoxide; the semiconductor material comprises at least one of titanium dioxide, perovskite and bismuth oxyhalide; the raw materials of the semiconductor material comprise at least one of tetrabutyl titanate, titanium tetrachloride, strontium chloride, lanthanum nitrate, cerium nitrate, iron nitrate, bismuth chloride, bismuth nitrate and ammonium oxalate.

2. The method of treating manganese-containing organic wastewater according to claim 1, characterized by, the carbonate comprises sodium carbonate and / or potassium carbonate; and / or, the manganese in the manganese-containing organic wastewater comprises divalent manganese ions, and the mass ratio of carbonate ions to divalent manganese ions in the carbonate is 1.0-1.

5.

3. The method of treating manganese-containing organic wastewater according to claim 1, characterized in that, the composition of the manganese-containing organic wastewater comprises: COD 90000-200000 mg / L, divalent manganese ions 30000-80000 mg / L, sulfate ions 50000-100000 mg / L, and pH 4-7.

4. The method of treating manganese-containing organic wastewater according to claim 1, wherein the reagent for the washing is an organic reagent; and / or, the drying temperature is 50-150 DEG C; and / or, the first calcination temperature is 300-1200 DEG C, and the first calcination time is 3-7 h.

5. The method of treating manganese-containing organic wastewater according to claim 1, wherein the mass ratio of the manganese oxide material to the semiconductor material is (7-13):(2-4).

6. The method for treating manganese-containing organic wastewater according to claim 1, characterized in that: the second calcination temperature is 400-600 DEG C, and the second calcination time is 1-5 h; and / or, the raw materials participating in the photo-Fenton reaction and the photocatalytic reaction further comprise persulfate, and the mass ratio of the mixed filtrate, the composite catalyst, the hydrogen peroxide and the persulfate is (5000-10000):(30-150):(400-2500):(100-500).

7. The method of treating manganese-containing organic wastewater according to claim 1, wherein the mass ratio of the mixed filtrate, the composite catalyst and the hydrogen peroxide is (5000-10000):(30-150):(400-2500); and / or, the light irradiation is realized by light source irradiation, and the light source comprises at least one of mercury lamp, sodium lamp, xenon lamp and halogen lamp; and / or the light has an energy density of 200-400 W / m 2 ; and / or, the light irradiation time is 6-10 h; and / or, the organic pollutants comprise at least one of ethanol, acetic acid, N,N-dimethylformamide, pyridine and pyrimidine.

8. The method of treating manganese-containing organic wastewater according to any one of claims 1 to 7, characterized in that, The method for treating manganese-containing organic wastewater further comprises: carrying out second filtration on the treated wastewater to obtain an ineffective composite catalyst and a third filtrate; carrying out calcination on the ineffective composite catalyst to restore activity; and / or, discharging or recycling the third filtrate.

9. The method of treating manganese-containing organic wastewater according to claim 8, characterized in that, The burning temperature is 300-1200℃, and the burning time is 1-3h.

10. A system for treating manganese-containing organic wastewater, characterized by comprising: It comprises: a reaction separation unit (2) connected with a raw water storage tank (1) containing manganese-containing organic wastewater and a carbonate storage tank (3), and manganese in the manganese-containing organic wastewater is removed by a chemical precipitation method to obtain manganese carbonate mud and a first filtrate; a purification treatment device (4) with an inlet connected with the reaction separation unit (2) and an organic reagent storage box (5) for storing organic reagents, so as to wash the manganese carbonate mud from the reaction separation unit (2) and perform solid-liquid separation to obtain manganese carbonate mud filter cake and a second filtrate; and an outlet connected with a material drying box (6) for drying treatment of the manganese carbonate mud filter cake and a high-temperature heating instrument (7) for obtaining manganese oxide material from the manganese carbonate mud filter cake through first calcination; a catalyst preparation unit (8) connected with the high-temperature heating instrument (7) and a raw material storage tank of semiconductor material, for synthesizing a composite catalyst through second calcination of the manganese oxide material and raw semiconductor material from the raw material storage tank of semiconductor material; a catalytic degradation unit (9) connected with the reaction separation unit (2), the purification treatment device (4), the catalyst preparation unit (8), and a hydrogen peroxide / persulfate preparation room (10), for causing the mixed filtrate of the first filtrate and the second filtrate to undergo a photo-Fenton reaction and a photocatalytic reaction with the composite catalyst, hydrogen peroxide from the hydrogen peroxide / persulfate preparation room (10), or hydrogen peroxide and persulfate under illumination conditions from an illumination device, so as to remove organic pollutants in the mixed filtrate; the manganese oxide material comprises trimanganese tetraoxide; the semiconductor material comprises at least one of titanium dioxide, perovskite, and bismuth oxyhalide; the raw material of the semiconductor material comprises at least one of tetrabutyl titanate, titanium tetrachloride, strontium chloride, lanthanum nitrate, cerium nitrate, iron nitrate, bismuth chloride, bismuth nitrate, and ammonium oxalate.

11. The system for treating manganese-containing organic wastewater according to claim 10, wherein The system for treating manganese-containing organic wastewater further comprises a calcination unit connected with the catalytic degradation unit, for recovering the activity of the composite catalyst discharged from the catalytic degradation unit through calcination.

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