A Fenton iron sludge treatment method and device

Abstract

The present invention provides a Fenton iron sludge treatment method and device, comprising the following steps: allowing the Fenton iron sludge to enter an iron reduction unit, undergoing reduction treatment under the action of dissimilatory iron-reducing bacteria, reducing the trivalent iron in the Fenton iron sludge to divalent iron through the reduction treatment to obtain reduced iron sludge; allowing at least a portion of the reduced iron sludge to enter a bioleaching unit, undergoing bioleaching treatment under the action of specific microorganisms to obtain a first mixed liquid; dehydrating the first mixed liquid to obtain an aqueous phase and dehydrated sludge, respectively; and returning the aqueous phase to the bioleaching system to participate in the bioleaching treatment. The present invention can solve technical problems existing in the prior art, such as the need for additional acid, the generation of a large amount of strongly acidic water, the susceptibility to environmental pollution, the inability to recycle iron, and high costs.

Description

Technical Field

[0001] The present invention relates to the field of environmental engineering, and in particular to a Fenton iron sludge treatment method and device. Background Art

[0002] Fenton iron sludge is an iron-containing sludge produced during the Fenton oxidation process to treat wastewater. The Fenton oxidation process is an advanced oxidation technology that is widely used to treat high-concentration, difficult-to-degrade organic wastewater such as dye wastewater, landfill leachate, and papermaking wastewater. 2+ It reacts with H₂O₂ to generate highly oxidizing hydroxyl radicals, which oxidize and decompose organic pollutants in the wastewater. During the treatment process, a large amount of iron-containing sludge, known as Fenton iron sludge, is produced. This iron sludge contains a large amount of organic matter, parasitic pathogens, heavy metals, and other impurities. Furthermore, Fenton iron sludge has poor dehydration properties, resulting in a high moisture content after dehydration. If Fenton iron sludge is not properly treated and is directly discharged into the environment, it will occupy a large amount of land, damage soil structure, contaminate water resources, and cause serious environmental pollution problems. Furthermore, if heavy metals in the iron sludge are transferred to the soil or groundwater with landfill leachate, they can cause secondary pollution.

[0003] In the relevant technologies, the main treatment methods for Fenton iron sludge and other sludges include acid dissolution and bioleaching. However, the dehydration efficiency of Fenton iron sludge by existing treatment methods still needs to be further improved. At the same time, there are problems such as the need to add additional acid, the generation of a large amount of strongly acidic water, easy environmental pollution, the inability to recycle iron elements, and high costs.

[0004] Specifically, the acid dissolution method requires the use of a large amount of acid, which has the problems of high cost and easy environmental pollution. For example, patent document CN 110877956A discloses a device and method for treating Fenton iron sludge, in which microorganisms containing iron-reducing bacteria are used to reduce the trivalent iron in the Fenton iron sludge to divalent iron, and then the mixed solution containing divalent iron produced after the reaction is passed into an acid dissolution tank. Acid is added to the acid dissolution tank 4, and then the mixture is allowed to settle. The supernatant containing divalent iron ions is returned to the Fenton reactor. In this way, under acidic conditions, the divalent iron ions are not easily oxidized to trivalent iron, which is conducive to starting the Fenton reaction, thereby achieving the purpose of treating the Fenton iron sludge. This treatment method requires additional acid, and when the supernatant containing divalent iron ions is refluxed to the Fenton reactor, the biodegradable COD is also refluxed, increasing the Fenton treatment load.

[0005] In addition, bioleaching is a method of using the life activities of acidophilic thiobacillus bacteria to oxidize ferrous ions and reduced sulfur into high-valent states, in which H +Biotechnology that creates a highly oxidizing environment. This technology utilizes Acidithiobacillus bacteria to treat sludge, improving its dewatering properties and potentially eliminating malodorous substances and killing or inhibiting pathogens. However, current bioleaching processes for sludge treatment produce highly acidic water, which is corrosive, difficult to dispose of, and prone to environmental pollution. For example, patent document CN 106186595A discloses a process for treating sludge using an integrated bioleaching apparatus. The filtrate produced by the bioleaching process is highly acidic, corrosive, and difficult to dispose of. Summary of the Invention

[0006] The present invention provides a Fenton iron sludge treatment method and device, which at least solves the technical problems existing in the prior art, such as the need to add additional acid, the generation of a large amount of strongly acidic water, the susceptibility to environmental pollution, the inability to recycle iron elements, and the high cost.

[0007] In one aspect of the present invention, a Fenton iron sludge treatment method is provided, comprising the following steps: allowing the Fenton iron sludge to enter an iron reduction unit, undergoing reduction treatment under the action of dissimilatory iron-reducing bacteria, reducing the trivalent iron in the Fenton iron sludge to divalent iron through the reduction treatment, and obtaining reduced iron sludge; allowing at least a portion of the reduced iron sludge to enter a bioleaching unit, undergoing bioleaching treatment under the action of specific microorganisms, and obtaining a first mixed liquid; dehydrating the first mixed liquid to obtain an aqueous phase and dehydrated sludge, respectively; and returning the aqueous phase to the bioleaching unit to participate in the bioleaching treatment.

[0008] According to one embodiment of the present invention, the iron reduction unit includes a microbial fuel cell, which includes a bioanode chamber, a biocathode chamber, and a proton exchange membrane arranged between the bioanode chamber and the biocathode chamber; the bioanode chamber is provided with a bioanode material, and the bioanode material is inoculated with the dissimilatory iron-reducing bacteria; oxygen is present in the biocathode chamber; the Fenton iron mud enters the bioanode chamber for the reduction treatment; preferably, the reduction treatment time is 6 to 12 hours.

[0009] According to one embodiment of the present invention, the iron reduction unit includes an iron reduction reactor, and the Fenton iron mud enters the iron reduction reactor for the reduction treatment; wherein the conditions of the reduction treatment are: temperature of 25°C to 35°C, pH of 6.5 to 7.5, and residence time of 12 to 24 hours.

[0010] According to one embodiment of the present invention, the specific microorganisms include Acidithiobacillus; preferably, the Acidithiobacillus includes Thiobacillus ferrooxidans and / or Thiobacillus thiooxidans.

[0011] According to one embodiment of the present invention, before the bioleaching treatment, a bacterial solution containing the specific microorganism is inoculated into the bioleaching unit, the bioleaching unit contains sludge for inoculation of the specific microorganism, and the cell density of the specific microorganism in the bacterial solution is 10 7 ~10 8 / mL, and in terms of volume ratio, the volume of the bacterial liquid accounts for 5% to 20% of the sum of the volume of the bacterial liquid and the volume of the sludge that can be used for inoculation of the specific microorganisms.

[0012] According to one embodiment of the present invention, the temperature of the bioleaching treatment is 25°C to 35°C; and / or, during the bioleaching treatment, the residence time of the reduced iron mud is 40 to 60 hours; and / or, during the bioleaching treatment, the reduced iron mud entering the bioleaching unit is aerated by a blower aerator connected to the bioleaching unit; and / or, the pH of the first mixed liquid is 2 to 3; and / or, the dissolved oxygen of the first mixed liquid in the bioleaching unit is 3 to 6 mg / L; and / or, the bioleaching unit includes nutrients for providing nutrition for the specific microorganisms, the nutrients including an iron source and / or a sulfur source, the iron source including FeSO4 and / or FeCl2, and the sulfur source including S and / or Na2S2O3.

[0013] According to one embodiment of the present invention, a plate filter press and / or a belt filter press is used to perform the dehydration treatment on the first mixed liquid.

[0014] According to one embodiment of the present invention, the process of returning the aqueous phase to the bioleaching system unit to participate in the bioleaching treatment includes: mixing the aqueous phase with a portion of the reduced iron mud to obtain a second mixed liquid; and allowing the second mixed liquid to enter the bioleaching system unit to participate in the bioleaching treatment.

[0015] Another aspect of the present invention provides a Fenton iron sludge treatment device, which includes: an iron reduction unit for performing the reduction treatment; the iron reduction unit includes a first reduced iron sludge outlet and a second reduced iron sludge outlet; a bioleaching unit for performing the bioleaching treatment; the bioleaching unit includes a first reduced iron sludge inlet, a first mixed liquid outlet, and a second mixed liquid inlet, the first reduced iron sludge inlet being connected to the first reduced iron sludge outlet of the iron reduction unit; a dehydration unit for performing the dehydration treatment; the dehydration unit includes a first mixed liquid inlet and an aqueous phase outlet, the first mixed liquid inlet being connected to the first mixed liquid outlet of the bioleaching unit; a bypass ferrous dissolution unit including a second reduced iron sludge inlet, an aqueous phase inlet, and a second mixed liquid outlet, the second reduced iron sludge inlet being connected to the second reduced iron sludge outlet of the iron reduction unit, the aqueous phase inlet being connected to the aqueous phase outlet of the dehydration unit, and the second mixed liquid outlet being connected to the second mixed liquid inlet of the bioleaching unit.

[0016] According to one embodiment of the present invention, the iron reduction unit includes a microbial fuel cell and / or an iron reduction reactor; and / or the Fenton iron sludge device further includes an air aerator connected to the bioleaching unit.

[0017] The implementation of the present invention has at least the following beneficial effects:

[0018] (1) The trivalent iron in the Fenton iron sludge is reduced to divalent iron by the iron reduction unit, so that the iron in the reduced iron sludge exists in the form of divalent iron. At least part of the reduced iron sludge enters the bioleaching unit for bioleaching treatment, and the divalent iron therein can serve as a nutrient substrate (or energy substrate) for specific microorganisms. While the bioleaching is used to dehydrate, sterilize and deodorize the reduced iron sludge, the resource utilization of the iron in the Fenton iron sludge can be achieved, thereby reducing the reaction cost of bioleaching;

[0019] (2) The first mixed liquid produced after the bioleaching treatment is dehydrated. The aqueous phase produced after the dehydration treatment is a strongly acidic water body. The aqueous phase is fed back into the bioleaching system to participate in the bioleaching treatment, providing a strongly acidic environment for the materials in the bioleaching system, which is conducive to the dissolution of the divalent iron in the reduced iron mud entering the bioleaching system into ionic divalent iron, which serves as an energy substrate for specific microorganisms in the bioleaching unit.

[0020] Therefore, the present invention recovers the strongly acidic aqueous phase generated after the first mixed liquid is dehydrated, and uses it to dissolve the divalent iron in the reduced iron mud entering the bioleaching system into an ionic state, and then participate in the bioleaching reaction. On the one hand, the divalent iron dissolved in the ionic state can be used as an energy substrate for specific microorganisms in the bioleaching unit, which can reduce the additional nutrients added to the bioleaching system to provide nutrition for specific microorganisms, reduce costs, and at the same time achieve efficient utilization of the iron element in the Fenton iron mud; on the other hand, the strongly acidic aqueous phase generated after the dehydration treatment is returned to the bioleaching system for recycling, which can avoid the additional addition of acidic agents such as sulfuric acid, nitric acid, hydrochloric acid, and acetic acid to the bioleaching system, thereby reducing costs and avoiding the additional introduction of other impurities into the aqueous phase and dehydrated sludge. At the same time, it can also reduce the discharge of the strongly acidic aqueous phase, avoid environmental pollution, and reduce the cost of post-treatment of the strongly acidic aqueous phase, thereby achieving the goal of not adding additional acid, recycling the acidic water body, avoiding environmental pollution, reducing costs, and recycling the iron element. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a Fenton iron sludge treatment device according to one embodiment of the present invention.

[0022] Explanation of the reference numerals: 1: iron reduction unit; 2: bioleaching unit; 3: dehydration unit; 4: bypass ferrous dissolution unit; 5: reflux unit; 6: aerator; a: Fenton iron sludge; b1: first reduced iron sludge; b2: second reduced iron sludge; c: first mixed liquid; d: aqueous phase; e: second mixed liquid; f: dehydrated sludge; g: sludge. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below. The specific embodiments listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts are within the scope of protection of the present invention.

[0024] The present invention provides a Fenton iron sludge a treatment method, see Figure 1The method comprises the following steps: allowing Fenton iron sludge a to enter an iron reduction unit (or iron reduction treatment system) 1, and performing reduction treatment under the action of dissimilatory iron-reducing bacteria, thereby reducing the trivalent iron in the Fenton iron sludge a to divalent iron to obtain reduced iron sludge; allowing at least part of the reduced iron sludge (hereinafter referred to as the first reduced iron sludge b1 that enters the bioleaching unit) to enter a bioleaching unit (or sludge bioleaching system) 2, and performing bioleaching treatment under the action of specific microorganisms to obtain a first mixed liquid c; dehydrating the first mixed liquid c to obtain an aqueous phase d and a dehydrated sludge f; and returning the aqueous phase d to the bioleaching unit 2 to participate in the bioleaching treatment.

[0025] In this way, in the iron reduction unit 1, the trivalent iron in the Fenton iron sludge a is reduced to divalent iron by the dissimilatory iron-reducing bacteria, so that the iron element in the reduced iron sludge is mainly divalent iron. After the reduced iron sludge enters the bioleaching unit 2, it is subjected to bioleaching treatment under the action of specific microorganisms. In this process, the divalent iron in the reduced iron sludge is dissolved into an ionic state by the strong acidic solution produced by the bioleaching reaction in the bioleaching unit 2. The ionic divalent iron can be used as a nutrient substrate for the bioleaching reaction. The iron element in the Fenton iron sludge a can be utilized as a resource while using bioleaching to dehydrate, sterilize and deodorize the sludge, thereby improving the bioleaching efficiency and reducing the reaction cost of bioleaching.

[0026] In addition, the aqueous phase d produced after the first mixed liquid c is dehydrated is a strongly acidic water body (or strongly acidic water phase). After the strongly acidic water body is recovered and mixed with part of the above-mentioned reduced iron mud, it can promote the dissolution of the divalent iron produced by the iron reduction unit 1 into an ionic state, and then participate in the bioleaching reaction, thereby realizing the recycling of the strongly acidic water body, avoiding the additional addition of chemical agents such as sulfuric acid, nitric acid, hydrochloric acid, and acetic acid, and avoiding the introduction of other impurities, reducing the treatment cost of the strongly acidic water body and the cost of the bioleaching reaction, and improving the efficiency of the bioleaching reaction.

[0027] In some embodiments, the iron reduction unit 1 may include a microbial fuel cell including a bioanode chamber, a biocathode chamber, and a proton exchange membrane disposed between the bioanode chamber and the biocathode chamber.

[0028] Specifically, the bioanode chamber is provided with a bioanode material inoculated with dissimilatory iron-reducing bacteria, and oxygen exists in the biocathode chamber. The biocathode chamber may include cathode materials such as graphite fiber brushes and / or carbon felt.

[0029] Specifically, the dissimilatory iron-reducing bacteria may include one or more of Shewanella, Geobacter, and Clostridium.

[0030] In some embodiments, a gas containing oxygen may exist in the biocathode chamber. Specifically, the gas containing oxygen may be air. That is, air may exist in the biocathode chamber, so that oxygen exists in the biocathode chamber.

[0031] Specifically, Fenton iron mud a enters the above-mentioned biological anode chamber for reduction treatment. During the reduction treatment process, the organic matter adsorbed by the Fenton iron mud in the biological anode chamber is oxidized and degraded, and at the same time, trivalent iron Fe(III) is reduced to divalent iron Fe(II) under the action of dissimilatory iron-reducing bacteria. The oxygen in the biological cathode chamber is reduced as an electron acceptor, and the H generated in the biological anode chamber is reduced. + It passes through the proton exchange membrane to the cathode chamber and reacts with the reduced oxygen to produce water.

[0032] In the embodiment of the present invention, conventional proton exchange membranes in the art may be used.

[0033] Specifically, the Fenton iron mud a enters the above-mentioned bioanode chamber for reduction treatment, and the reduction treatment time can be 6 to 12 hours, for example, 6 hours, 8 hours, 10 hours, 12 hours or a range consisting of any two thereof.

[0034] In other embodiments, the iron reduction unit 1 may be a microbial iron reduction reactor, and the Fenton iron sludge a enters the iron reduction reactor for reduction treatment.

[0035] Specifically, when the iron reduction reactor is used for reduction treatment, the reduction treatment temperature (reaction temperature in the iron reduction unit 1) can be 25-35°C, for example, 25°C, 27°C, 29°C, 31°C, 33°C, 35°C or a range consisting of any two thereof. During the reduction treatment, the pH of Fenton iron mud a can be 6.5-7.5, for example, 6.5, 6.7, 6.9, 7.1, 7.3, 7.5 or a range consisting of any two thereof. The residence time of Fenton iron mud a can be 12-24h, for example, 12h, 14h, 16h, 18h, 20h, 22h, 24h or a range consisting of any two thereof. In this way, the trivalent iron in Fenton iron mud a is reduced to divalent iron, providing nutrition for specific microorganisms in the bioleaching system.

[0036] In a specific implementation, the pH of the Fenton iron mud a maintained during the reduction treatment can be 6.5-7.5. The pH of the Fenton iron mud a in the iron reduction unit 1 can be adjusted by alkali, which can include inorganic alkali, such as sodium hydroxide.

[0037] In some embodiments, the specific microorganisms may include Acidithiobacillus, which may include Thiobacillus ferrooxidans and / or Thiobacillus thiooxidans.

[0038] In a specific implementation, before the bioleaching treatment, the bacterial solution containing the above-mentioned specific microorganisms can be inoculated into the bioleaching unit 2, and the bioleaching unit 2 is added with sludge g for inoculation of specific microorganisms. The bacterial solution containing specific microorganisms can be inoculated into the sludge g in the bioleaching unit 2, and the bacterial cell density in the bacterial solution can be 10 7 ~10 8 / mL (for example, the bacterial density can be 10 8 / mL), and in terms of volume ratio, the volume of the bacterial liquid can account for 5% to 20% of the sum of the volume of the bacterial liquid and the volume of the sludge g in the bioleaching unit 2 that can be used for inoculation of specific microorganisms, for example, 5%, 10%, 15%, 20% or a range consisting of any two thereof.

[0039] The sludge g in the bioleaching unit 2 that can be used for inoculation of specific microorganisms can be ordinary municipal sludge.

[0040] Specifically, the bioleaching unit 2 may be a conventional bioleaching reactor in the art, and is not particularly limited thereto.

[0041] In some embodiments, the temperature of the bioleaching treatment (or the temperature of the bioleaching reaction) can be 25°C to 35°C, for example, 25°C, 27°C, 28°C, 29°C, 31°C, 33°C, 35°C or a range consisting of any two thereof.

[0042] In some embodiments, during the bioleaching process, the residence time of the first reduced iron sludge b1 entering the bioleaching unit 2 may be 40 to 60 hours, such as 40 hours, 45 hours, 50 hours, 55 hours, 60 hours, or any two thereof.

[0043] In addition, the pH of the first mixed liquid c may be in the range of 2 to 3, for example, 2, 2.2, 2.4, 2.6, 2.8, 3, or any two thereof.

[0044] In addition, the dissolved oxygen (DO) of the first mixed liquid c in the bioleaching unit 2 may be 3 to 6 mg / L, for example, 3 mg / L, 4 mg / L, 5 mg / L, 6 mg / L, or any two thereof.

[0045] In addition, during the bioleaching process, the reduced iron sludge entering the bioleaching unit 2 may be aerated by the air aerator 6 connected to the bioleaching unit 2 .

[0046] In the embodiment of the present invention, the nutrients (or nutrient substrates) for the specific microorganisms in the bioleaching reaction can be obtained from the Fenton iron mud a or can be added additionally.

[0047] In some embodiments, the nutrient substrate for specific microorganisms may include an iron source and / or a sulfur source. The iron source may be FeSO4 and / or FeCl2, and the sulfur source may be S and / or Na2S2O3.

[0048] As described above, the ferrous iron in the reduced iron sludge entering bioleaching unit 2 is dissolved into ionic ferrous iron in a strongly acidic environment. This ionic ferrous iron serves as a nutrient substrate for specific microorganisms in the bioleaching reaction, simultaneously dehydrating, sterilizing, and deodorizing the sludge and achieving resource utilization of the Fenton iron sludge (a), thereby reducing bioleaching reaction costs. Generally, the reduced iron sludge entering bioleaching unit 2 provides a source of ferrous iron, such as FeSO4 and / or FeCl2, which serves as a nutrient for specific microorganisms.

[0049] In the above-mentioned treatment process of Fenton iron mud, the Fenton iron mud is first reduced by dissimilatory iron-reducing bacteria and then enters the bioleaching unit 2 for bioleaching treatment, thereby improving the dewatering performance of the Fenton iron mud.

[0050] Specifically, the obtained first mixed liquid c can be dehydrated by a dehydration unit (or sludge solid-liquid separation system) 3. The dehydration unit 3 can be a filter press, specifically a plate filter press and / or a belt filter press. After dehydration, the obtained filtrate is the above-mentioned aqueous phase d.

[0051] In the embodiment of the present invention, a conventional plate filter press (plate and frame filter press) and / or belt filter press in the art may be used for dehydration treatment.

[0052] In some embodiments, the process of returning the aqueous phase d to the bioleaching unit 2 to participate in the bioleaching treatment may include: mixing the aqueous phase d with a portion of the reduced iron sludge (second reduced iron sludge b2) to obtain a second mixed liquid e; and allowing the second mixed liquid e to enter the bioleaching unit 2 to participate in the bioleaching treatment.

[0053] Specifically, the aqueous phase d obtained after dehydration of the first mixed liquid c is a strongly acidic water body, and the strongly acidic water body enters the bypass ferrous dissolution unit (or bypass ferrous dissolution system) 4 through the reflux unit (or sludge filtrate reflux system) 5, and part of the reduced iron mud (second reduced iron mud b2) enters the bypass ferrous dissolution unit 4, and the strongly acidic water body entering the bypass ferrous dissolution unit 4 and the reduced iron mud (i.e., the second reduced iron mud b2) entering the bypass ferrous dissolution unit 4 are mixed to form a second mixed liquid e, and then the second mixed liquid e enters the bioleaching unit 2 to participate in the bioleaching reaction. In the bypass ferrous iron dissolution unit 4, the aqueous phase d acts as a strongly acidic water body, providing an acidic environment that promotes the dissolution of the ferrous iron in the second reduced iron sludge b2 into ionic ferrous iron. The resulting second mixed liquid e is also strongly acidic. After entering the bioleaching unit 2, the second mixed liquid e provides a strongly acidic environment for the reaction system in the bioleaching unit 2, promoting the dissolution of the ferrous iron in the first reduced iron sludge b1 entering the bioleaching unit 2 into ionic ferrous iron. Thus, in the bioleaching unit 2, the ferrous iron in the reduced sludge output from the iron reduction unit is promoted to dissolve into ionic ferrous iron, providing nutrition for the specific microorganisms in the bioleaching unit 2. Through the above process, the aqueous phase d is utilized, participating in the bioleaching reaction in the bioleaching unit 2, and improving the efficiency of the bioleaching reaction.

[0054] Specifically, the reflux unit 5 is connected between the dehydration unit 3 and the bypass ferrous dissolution unit 4, and is used to connect the dehydration unit 3 and the bypass ferrous dissolution unit 4, so that the water phase d produced by the dehydration unit 3 can be refluxed into the bypass ferrous dissolution unit 4 through the reflux unit 5. The reflux unit 5 can be a connecting structure such as a pipeline connecting the dehydration unit 3 and the bypass ferrous dissolution unit 4.

[0055] In some embodiments, the process of mixing the aqueous phase d and the second reduced iron sludge b2 can be performed at room temperature, that is, the temperature of the bypass ferrous dissolution unit 4 can be room temperature.

[0056] The present invention also provides a Fenton iron sludge a disposal device, comprising:

[0057] The iron reduction unit 1, i.e., for performing reduction treatment, may include a first reduced iron sludge outlet and a second reduced iron sludge outlet;

[0058] The bioleaching unit 2 is used for bioleaching treatment and may include a first reduced iron mud inlet, a first mixed liquid outlet, and a second mixed liquid inlet, wherein the first reduced iron mud inlet is connected to the first reduced iron mud outlet of the iron reduction unit 1;

[0059] The dehydration unit 3 is used for dehydration treatment and may include a first mixed liquid inlet and a water phase outlet, wherein the first mixed liquid inlet is connected to the first mixed liquid outlet of the bioleaching unit 2;

[0060] In a specific embodiment, the dehydration unit 3 may further include a dehydrated sludge outlet for outputting the dehydrated sludge f;

[0061] The bypass ferrous dissolution unit 4 may include a second reduced iron mud inlet, an aqueous phase inlet, and a second mixed liquid outlet. The second reduced iron mud inlet is connected to the second reduced iron mud outlet of the iron reduction unit 1, the aqueous phase inlet is connected to the aqueous phase outlet of the dehydration unit 3, and the second mixed liquid outlet is connected to the second mixed liquid inlet of the bioleaching unit 2.

[0062] Specifically, the iron reduction unit 1 may include a microbial fuel cell and / or an iron reduction reactor, and the Fenton iron sludge device a may further include an air aerator 6 connected to the bioleaching unit.

[0063] In addition, the iron reduction unit may also include a Fenton iron sludge inlet.

[0064] In a specific implementation, Fenton iron mud a enters the iron reduction unit 1 from the Fenton iron mud inlet of the iron reduction unit 1, and is reduced in the iron reduction unit 1 to obtain reduced iron mud. The first reduced iron mud b1 is output from the first reduced iron mud outlet of the iron reduction unit 1, enters the bioleaching unit 2 through the first reduced iron mud inlet of the bioleaching unit 2, and obtains the first mixed liquid c after the first reduced iron mud b1 is bioleached in the bioleaching unit 2. The first mixed liquid c is output through the first mixed liquid outlet of the bioleaching unit 2, enters the dehydration unit 3 through the first mixed liquid inlet of the dehydration unit 3, and is dehydrated in the dehydration unit 3. After treatment, an aqueous phase d and a dewatered sludge f are obtained. The aqueous phase d is output through the aqueous phase outlet of the dehydration unit 3, passes through the reflux unit 5, and enters the bypass ferrous dissolution unit 4 through the aqueous phase inlet of the bypass ferrous dissolution unit 4. At the same time, the second reduced iron mud b2 in the iron reduction unit 1 enters the bypass ferrous dissolution unit 4 through the second reduced iron mud outlet of the iron reduction unit 1 and is mixed with the aqueous phase d in the bypass ferrous dissolution unit 4 to obtain a second mixed liquid e. The second mixed liquid e leaves through the second mixed liquid outlet of the bypass ferrous dissolution unit 4, enters the bioleaching unit 2 through the second mixed liquid inlet of the bioleaching unit 2, and participates in the bioleaching treatment.

[0065] During the above treatment process, the aqueous phase produced by the Fenton iron sludge a after passing through the dehydration unit 3 is refluxed to the bypass ferrous dissolution unit 4, promoting the existence of divalent iron in a free state. This process can not only recycle the strongly acidic aqueous phase d, but also avoid the additional addition of chemical agents such as sulfuric acid, nitric acid, hydrochloric acid, and acetic acid. In addition, the iron reduction unit 1 reduces the trivalent iron in the Fenton iron sludge a to divalent iron, and uses the dissolved divalent iron as a specific microbial energy substrate for the sludge bioleaching unit 2, thereby realizing the resource utilization of Fenton sludge and reducing the energy substrate cost of sludge bioleaching.

[0066] In the embodiment of the present invention, after the dewatered sludge f is discharged through the dewatered sludge outlet of the dehydration unit 3, it can be post-processed according to conventional methods in the art, such as incineration, land utilization, composting, etc.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A Fenton iron sludge treatment method, characterized in that: The following steps are involved: The Fenton iron mud enters the iron reduction unit and is reduced under the action of dissimilatory iron-reducing bacteria, thereby reducing the trivalent iron in the Fenton iron mud to divalent iron to obtain reduced iron mud; allowing at least a portion of the reduced iron sludge to enter a bioleaching unit and undergo bioleaching treatment under the action of specific microorganisms to obtain a first mixed liquid; Dehydrating the first mixed liquid to obtain an aqueous phase and dehydrated sludge; The aqueous phase is returned to the bioleaching unit to participate in the bioleaching treatment.

2. The Fenton iron sludge treatment method according to claim 1, wherein: The iron reduction unit includes a microbial fuel cell, which includes a bioanode chamber, a biocathode chamber, and a proton exchange membrane disposed between the bioanode chamber and the biocathode chamber; The bioanode chamber is provided with a bioanode material, and the bioanode material is inoculated with the dissimilatory iron-reducing bacteria; Oxygen exists in the biological cathode chamber; The Fenton iron mud enters the bioanode chamber for the reduction treatment; The reduction treatment time is 6 to 12 hours.

3. The Fenton iron sludge treatment method according to claim 1, wherein: The iron reduction unit includes an iron reduction reactor, and the Fenton iron mud enters the iron reduction reactor for the reduction treatment; wherein the conditions of the reduction treatment are: temperature of 25°C to 35°C, pH of 6.5 to 7.5, and residence time of 12 to 24 hours.

4. The Fenton iron sludge treatment method according to claim 1, characterized in that: The specific microorganisms include acidthiobacillus; the acidthiobacillus includes ferrooxidans and / or thiooxidans.

5. The Fenton iron sludge treatment method according to claim 1 or 4, characterized in that: Before the bioleaching treatment, a bacterial solution containing the specific microorganism is inoculated into the bioleaching unit, the bioleaching unit contains sludge for inoculation of the specific microorganism, and the cell density of the specific microorganism in the bacterial solution is 10 7 ~10 8 / mL, and in terms of volume ratio, the volume of the bacterial liquid accounts for 5% to 20% of the sum of the volume of the bacterial liquid and the volume of the sludge that can be used for inoculation of the specific microorganisms.

6. The Fenton iron sludge treatment method according to claim 1 or 4, characterized in that: The temperature of the bioleaching treatment is 25°C to 35°C; And / or, during the bioleaching process, the reduced iron sludge has a residence time of 40 to 60 hours; and / or, during the bioleaching process, aeration treatment is performed on the reduced iron sludge entering the bioleaching unit by an air aerator connected to the bioleaching unit; and / or, the pH of the first mixed liquid is 2 to 3; and / or, the dissolved oxygen content of the first mixed liquid in the bioleaching unit is 3 to 6 mg / L; And / or, the bioleaching unit includes nutrients for providing nutrition for the specific microorganisms, the nutrients include an iron source and / or a sulfur source, the iron source includes FeSO4 and / or FeCl2, and the sulfur source includes S and / or Na2S2O3.

7. The Fenton iron sludge treatment method according to claim 1, characterized in that: The first mixed liquid is dehydrated by using a plate filter press and / or a belt filter press.

8. The Fenton iron sludge treatment method according to claim 1, characterized in that: The process of returning the aqueous phase to the bioleaching unit to participate in the bioleaching treatment includes: mixing the aqueous phase and a portion of the reduced iron mud to obtain a second mixed liquid; The second mixed liquid is allowed to enter the bioleaching unit to participate in the bioleaching treatment.

9. A Fenton iron sludge treatment device for implementing the Fenton iron sludge treatment method according to any one of claims 1 to 8, characterized in that: The Fenton iron sludge treatment device comprises: An iron reduction unit is used to perform the reduction treatment; the iron reduction unit comprises a first reduced iron mud outlet and a second reduced iron mud outlet; A bioleaching unit for performing the bioleaching treatment; the bioleaching unit comprises a first reduced iron sludge inlet, a first mixed liquid outlet, and a second mixed liquid inlet, wherein the first reduced iron sludge inlet is connected to the first reduced iron sludge outlet of the iron reduction unit; a dehydration unit for performing the dehydration treatment; the dehydration unit comprises a first mixed liquid inlet and an aqueous phase outlet, the first mixed liquid inlet being in communication with the first mixed liquid outlet of the bioleaching unit; The bypass ferrous dissolution unit includes a second reduced iron mud inlet, an aqueous phase inlet, and a second mixed liquid outlet, wherein the second reduced iron mud inlet is connected to the second reduced iron mud outlet of the iron reduction unit, the aqueous phase inlet is connected to the aqueous phase outlet of the dehydration unit, and the second mixed liquid outlet is connected to the second mixed liquid inlet of the bioleaching unit.

10. The Fenton iron sludge treatment device according to claim 9, characterized in that: The iron reduction unit includes a microbial fuel cell and / or an iron reduction reactor; And / or, the Fenton iron sludge device further includes an air aerator connected to the bioleaching unit.

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