Magnetic field reinforced anaerobic reactor and wastewater resourceful treatment method

Abstract

The invention relates to the technical field of wastewater resourceful treatment, in particular to a magnetic field reinforced anaerobic reactor and a wastewater resourceful treatment method. The magnetic field intensified anaerobic reactor comprises an anaerobic reactor body and a plurality of magnetic blocks fixed on the outer surface of the anaerobic reactor body, the plurality of magnetic blocks are divided into a plurality of rows and surround the outer surface of the anaerobic reactor body, and the magnetic blocks in each row are circularly arranged in the sequence of left, upper, right and lower according to the magnetic field direction. The magnetic field enhanced anaerobic reactor can utilize the magnetic field to convert the ascending or descending motion of microorganisms in the reactor depending on water flow, bubbles or self into magnetic induction line cutting motion, convert kinetic energy into electric potential energy and enhance electron transfer between acetogens and methanogens; the utilization degree of organic matters in the wastewater by the acid-producing bacteria and the methane-producing process of reducing carbon dioxide by utilizing electrons by the methane-producing bacteria are improved, and the energy utilization and methane-producing efficiency in the anaerobic reactor are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater resource treatment, and particularly to a magnetic field enhanced anaerobic reactor and a wastewater resource treatment method. Background Art

[0002] Anaerobic fermentation is an important waste resource technology, which can produce clean energy such as methane and hydrogen while treating waste such as wastewater and livestock manure. However, general anaerobic reactors face problems such as low efficiency, unstable operation, and inability to treat high-load organic wastewater. Anaerobic fermentation mainly realizes through the electron transfer between syntrophic microorganisms formed by acid-producing bacteria and methanogenic bacteria, which is considered the key to overcoming these problems. Current research mainly starts from electron transfer to improve the efficiency of anaerobic fermentation, hoping to establish and strengthen the direct interspecies electron transfer (DIET) between syntrophic microorganisms in the reactor.

[0003] Most of the existing research mainly establishes and strengthens the electron transfer between microorganisms by adding carbon-based conductive materials (such as granular activated carbon, biochar, carbon nanotubes, and graphene, etc.) and iron-based conductive materials (such as magnetite, zero-valent iron, and stainless steel, etc.) into the reactor, adding a constant or variable voltage inside the reactor, or applying a moving magnetic field outside the reactor. For example, Chinese Patent CN117125807A discloses a sewage treatment system and method for nitritation based on a microbial electrolytic cell, Chinese Patent CN105236565B discloses a method for improving the COD removal efficiency of wastewater anaerobic treatment by magnetic field enhanced iron powder, and Chinese Patent CN117247146A discloses a method for promoting anaerobic digestion of municipal sludge by magnetic field-driven magnetic biochar. However, the above methods are relatively complex, and require additional input of energy or high-cost magnetic field generating devices, which have high requirements for application scenarios and limited application scope. Summary of the Invention

[0004] In view of this, the present invention provides a magnetic field enhanced anaerobic reactor and a wastewater resource treatment method. The anaerobic reactor provided by the present invention has a simple structure, is easy to build, does not require additional input of energy, and is applicable to most anaerobic reactors, and can effectively treat high-load organic wastewater.

[0005] On the one hand, the present invention provides a magnetic field enhanced anaerobic reactor, including an anaerobic reactor body and a plurality of magnetic blocks fixed on the outer surface of the anaerobic reactor body, wherein the plurality of magnetic blocks are divided into multiple rows and surround the outer surface of the anaerobic reactor body, and the magnetic blocks in each row are arranged in a cycle in the order of magnetic field direction being left, up, right, and down.

[0006] In some embodiments of the present invention, the anaerobic reactor body is an upflow anaerobic sludge bed reactor.

[0007] In some embodiments of the present invention, the magnetic block is an N35 magnetic block.

[0008] In some embodiments of the present invention, the effective volume of the anaerobic reactor body is 1 L, the inner diameter is 60 mm, and the height is 356 mm; 8 rows of magnetic blocks are arranged at equal intervals on the outer surface of the anaerobic reactor body, and each row of magnetic blocks is provided with 36 magnetic blocks. The volume of the magnetic block is 1 cm 3 .

[0009] On the other hand, the present invention also provides a method for treating wastewater for resource utilization, comprising the following steps:

[0010] (1) Inoculate the magnetite-containing anaerobic granular sludge into the magnetic field-enhanced anaerobic reactor according to any one of the foregoing technical solutions.

[0011] (2) Introduce wastewater into the magnetic field-enhanced anaerobic reactor for wastewater treatment to obtain treated wastewater and methane.

[0012] In some embodiments of the present invention, the inoculation amount of the magnetite-containing anaerobic granular sludge is 225 - 275 mL / L.

[0013] In some embodiments of the present invention, the preparation method of the magnetite-containing anaerobic granular sludge comprises the following steps:

[0014] (1) Mix the sludge from the sewage treatment plant with nano-magnetite and synthetic wastewater in a ratio of 115 - 125 mL: 6 g: 275 - 285 mL to obtain a sludge-magnetite mixture; wherein the ethanol concentration in the synthetic wastewater is 4.6 - 4.8 g / L, and the carbon-nitrogen ratio is 20 - 26:1.

[0015] (2) Cultivate the sludge-magnetite mixture at 35 - 37 °C. When methane can no longer be produced, add ethanol to make the ethanol concentration in the system the same as that in the initial sludge-magnetite mixture, and continue to cultivate until methane can no longer be produced. Then repeat the foregoing step of adding ethanol and continue to cultivate until methane can no longer be produced to obtain the magnetite-containing anaerobic granular sludge.

[0016] In some embodiments of the present invention, the diameter of the nano-magnetite is 30-50 nm. In some embodiments of the present invention, the synthetic wastewater includes substances with the following concentrations: 250 mg / L of K2HPO4, 250 mg / L of KH2PO4, 300 mg / L of MgCl2, 25 mg / L of CaCl2, 15 mg / L of MnCl2, 25 mg / L of FeCl3, 16 mg / L of NiSO4, 25 mg / L of CoCl2, 11.5 mg / L of ZnCl2, 10.5 mg / L of CuCl2, and 0.8 g / g COD of NaHCO3.

[0017] In some embodiments of the present invention, the hydraulic retention time of the wastewater is 8-24 h.

[0018] In some embodiments of the present invention, the temperature for wastewater treatment is 35-37 °C.

[0019] The present invention provides a magnetic field enhanced anaerobic reactor, which includes an anaerobic reactor body and a plurality of magnetic blocks fixed on the outer surface of the anaerobic reactor body. The plurality of magnetic blocks are divided into multiple rows and surround the outer surface of the anaerobic reactor body. The magnetic blocks in each row are arranged in a cycle in the order of left, up, right, and down according to the magnetic field direction. The magnetic blocks of the present invention are designed with the magnetic field direction arranged in the order of up, left, down, and right to intensify the relatively uniform magnetic field on one side. Combined with the anaerobic reactor, the movement of microorganisms in the reactor relying on water flow, bubbles or their own upward or downward movement is converted into the movement of cutting magnetic induction lines by the magnetic field, and the kinetic energy is converted into electrical potential energy that microorganisms can utilize, enhancing the electron transfer between acetogenic bacteria and methanogenic bacteria, improving the utilization rate of organic matter in wastewater by acidogenic bacteria and the process of methanogenic bacteria using electrons to reduce carbon dioxide to produce methane, and realizing the improvement of energy utilization and methane production efficiency in the anaerobic reactor.

[0020] In addition, when using the magnetic field enhanced anaerobic reactor provided by the present invention to treat wastewater, at high organic load or low hydraulic retention time, since the bubble generation speed or water flow speed can be increased, the movement speed of microorganisms cutting magnetic induction lines can be greatly increased, and the energy conversion efficiency can be improved. Therefore, this method can be applied to the rapid treatment of high organic load wastewater. Since the microbial aggregates consume kinetic energy and convert it into electrical potential energy when cutting magnetic induction lines in the reactor combined with the magnetic field, when using the anaerobic reactor of the present invention to treat wastewater, it can also prevent microorganisms from being washed out of the reactor, which is beneficial to the recovery of sludge microbial aggregates. In addition, when using the anaerobic reactor of the present invention to treat wastewater, the unvalued part of energy (i.e., the kinetic energy of microorganisms) is fully utilized, providing a feasible technical solution for improving the resource utilization efficiency of anaerobic reactor wastewater. Description of the Drawings

[0021] The above and other objects, features, and advantages of the present invention will be apparent from the following description of the gist of the present invention, preferred embodiments thereof, and the accompanying drawings, in which:

[0022] Figure 1 It is a schematic diagram of the layout in an embodiment of the present invention.

[0023] Figure 2 It is a schematic diagram of a magnetic field enhanced anaerobic reactor in an embodiment of the present invention.

[0024] Figure 3 is Figure 2 A schematic diagram of the distribution characteristics of the magnetic field direction of the shown magnetic field enhanced anaerobic reactor.

[0025] Figure 4 It is a magnetic field intensity distribution diagram of the magnetic field enhanced anaerobic reactor used in the embodiment of the present invention, where a shows the longitudinal magnetic field distribution of the anaerobic reactor, and b shows the transverse magnetic field distribution of the anaerobic reactor. Detailed Embodiments

[0026] The present invention will be described below through specific embodiments. Those skilled in the art can understand that the following specific embodiments are only for the purpose of illustration and do not limit the scope of the present invention in any way. In addition, in the following embodiments, unless otherwise specified, the reagents and equipment used are commercially available. If the specific processing conditions and methods are not clearly described in the following embodiments, the conditions and methods known in the art can be used for processing.

[0027] The present invention provides a magnetic field enhanced anaerobic reactor, which includes an anaerobic reactor body and a plurality of magnetic blocks fixed on the outer surface of the anaerobic reactor body, wherein the plurality of magnetic blocks are divided into multiple rows and surround the outer surface of the anaerobic reactor body, and the magnetic blocks in each row are arranged in a cycle in the order of the magnetic field direction being left, up, right, and down.

[0028] As Figure 1 shown, it is a schematic diagram of the layout of the magnetic blocks in an embodiment of the present invention. Figure 2 It is a schematic diagram of the magnetic field enhanced anaerobic reactor in an embodiment of the present invention. As Figure 2As shown in the figure, when using the anaerobic reactor, inoculate the sludge of 250 mL / L reactor in the effective working space 10 of the reactor. The wastewater enters the reactor from the bottom inlet 9, and the constant temperature water at 35 - 37 °C enters from the insulation layer inlet 8 and is discharged from the insulation layer outlet 3, so that the insulation layer 5 is maintained in an environment of 35 - 37 °C. Under the action of the specially arranged magnetic blocks 6, the kinetic energy generated by the movement of microorganisms is converted into electric potential energy, promoting the methane production efficiency. The generated gas is collected from the gas collection port 1, and the treated wastewater flows out of the anaerobic reactor from the outlet 2. The three-phase separator 4 is used to prevent the sludge from being washed out of the reactor. Appropriate sludge samples can be taken from the sludge sampling port 7 regularly for testing.

[0029] Use Maxwell software to model and simulate the distribution characteristics of the magnetic field direction in the reactor. The results are as Figure 3 shown. From Figure 3 it can be seen that the internally of the anaerobic reactor strengthened by magnetic field provided by the present invention is filled with a relatively uniform transverse magnetic field.

[0030] The present invention has no special limitation on the fixing method of the magnetic blocks, and it can be fixed on the outer surface of the anaerobic reactor body. In the embodiment of the present invention, by putting the magnetic blocks into the rubber tube according to the foregoing arrangement method, a magnetic strip that can surround the anaerobic reactor body is obtained, and then a plurality of magnetic strips are fixed parallel to the outer surface of the anaerobic reactor body at equal intervals.

[0031] The present invention has no special limitation on the anaerobic reactor body. In some embodiments of the present invention, the anaerobic reactor body is an upflow anaerobic sludge bed reactor.

[0032] In the present invention, those skilled in the art can select the size, shape and magnetic properties of the magnetic blocks according to the characteristics of the reactor. In some embodiments of the present invention, the magnetic blocks are N35 magnetic blocks. In the embodiment of the present invention, the magnetic blocks are cubes with a volume of 1 cm 3 .

[0033] In some embodiments of the present invention, the effective volume of the anaerobic reactor body is 1 L, the inner diameter is 60 mm, and the height is 356 mm; 8 rows of magnetic blocks are arranged at equal intervals on the outer surface of the anaerobic reactor body, and each row of magnetic blocks is provided with 36 magnetic blocks. The volume of the magnetic blocks is 1 cm 3 . Use Maxwell software to model and simulate the distribution of the magnetic field in the reactor. The results are as Figure 3 shown, in which the inner diameter of the simulated reactor is 60 mm. a shows the longitudinal magnetic field distribution of the anaerobic reactor, and b shows the transverse magnetic field distribution of the anaerobic reactor. The black wireframe represents the contour of the reactor. From Figure 3It can be seen that the magnetic field strength of the anaerobic reactor in this embodiment changes from 0.001 mT to 11 mT from the center to the inner wall of the reactor. It can be seen that the anaerobic reactor provided by the present invention intensifies the magnetic field on the side of the reactor, which can avoid the use of high-cost magnetic field generating devices.

[0034] The present invention also provides a method for treating wastewater for resource recovery, which includes the following steps:

[0035] (1) Inoculate the magnetic field-strengthened anaerobic reactor described in any of the foregoing technical solutions with anaerobic granular sludge containing magnetite.

[0036] (2) Feed wastewater into the magnetic field-strengthened anaerobic reactor for wastewater treatment to obtain treated wastewater and methane.

[0037] In the method for treating wastewater for resource recovery provided by the present invention, the magnetic field in the anaerobic reactor can convert the movement of microorganisms relying on water flow, bubbles and their own movement into cutting magnetic induction line movement, so as to convert kinetic energy into electric potential energy, rather than rotating the magnetic field itself to achieve the effect of cutting magnetic induction lines, avoiding additional energy input to the system. The electric potential energy can promote the electron transfer between acetic acid-producing bacteria and methane-producing bacteria, improve the utilization degree of substrates, and at the same time can promote the electrons in the environment to be utilized by methane-producing bacteria to combine with carbon dioxide to produce additional methane, realizing the double improvement of wastewater treatment and methane production efficiency. In addition, since the microbial aggregates are consumed by converting kinetic energy into electric potential energy when making cutting magnetic induction line movement in the reactor combined with the magnetic field, the method provided by the present invention can also prevent microorganisms from being washed out of the reactor, which is beneficial to the recovery of sludge microbial aggregates.

[0038] In some embodiments of the present invention, the inoculation amount of the anaerobic granular sludge containing magnetite is 225 - 275 mL / L, preferably 250 mL / L; the unit here represents the volume of sludge inoculated per unit reactor.

[0039] In some embodiments of the present invention, the preparation method of the anaerobic granular sludge containing magnetite includes the following steps:

[0040] (1) Mix the sludge from the sewage treatment plant with nano-magnetite and synthetic wastewater in a ratio of 115 - 125 mL: 6 g: 275 - 285 mL to obtain a sludge-magnetite mixture; the ethanol concentration in the synthetic wastewater is 4.6 - 4.8 g / L, and the carbon-nitrogen ratio is 20 - 26:1.

[0041] (2) Cultivate the sludge-magnetite mixture at 35 - 37 °C. When methane production ceases, add ethanol to make the ethanol concentration in the system the same as that in the initial sludge-magnetite mixture, and continue cultivation until methane production ceases. Then repeat the aforementioned step of adding ethanol and continue cultivation until methane production ceases to obtain anaerobic granular sludge containing magnetite.

[0042] The anaerobic granular sludge containing magnetite provided by the present invention enriches a large number of electroactive microorganisms, improves the electrical conductivity of the sludge, and can utilize electrical potential energy more effectively.

[0043] In the examples of the present invention, the sludge of the sewage treatment plant is the sludge of a sewage treatment plant treating ethanol and / or citric acid, and the total solid (TS) of the sludge is 8.5% - 10%, and the volatile solid (VS) is 6.5% - 7%.

[0044] In some embodiments of the present invention, the diameter of the magnetite is 30 - 50 nm.

[0045] In some embodiments of the present invention, the ratio of the sludge of the sewage treatment plant, nano-magnetite, and synthetic wastewater is 115 - 125 mL: 6 g: 275 - 285 mL, preferably 120 mL: 6 g: 280 mL.

[0046] In some embodiments of the present invention, the ethanol concentration in the synthetic wastewater is 4.6 - 4.8 g / L, preferably 4.79 g / L; the carbon-nitrogen ratio (mass ratio) is 20 - 26:1, preferably 25:1.

[0047] In some embodiments of the present invention, the synthetic wastewater contains the following concentrations of substances: 250 mg / L of K2HPO4, 250 mg / L of KH2PO4, 300 mg / L of MgCl2, 25 mg / L of CaCl2, 15 mg / L of MnCl2, 25 mg / L of FeCl3, 16 mg / L of NiSO4, 25 mg / L of CoCl2, 11.5 mg / L of ZnCl2, 10.5 mg / L of CuCl2, and 0.8 g / g COD of NaHCO3.

[0048] In some embodiments of the present invention, before adding ethanol, first purge the equipment used for cultivation with nitrogen to maintain an anaerobic environment.

[0049] In some embodiments of the present invention, the cultivation is carried out at 35 - 37 °C, preferably at 36 °C; the cultivation is carried out in a constant temperature water bath oscillator to ensure a constant cultivation temperature. In the examples of the present invention, the rotation speed of the constant temperature water bath oscillator is 120 rpm.

[0050] In some embodiments of the present invention, after the cultivation is completed, the anaerobic granular sludge containing magnetite is obtained by pouring out the supernatant.

[0051] The present invention does not have special limitations on the specific equipment used in the process of preparing the anaerobic granular sludge containing magnetite, as long as the anaerobic granular sludge containing magnetite required by this application can be obtained. In the embodiments of the present invention, before the second addition of ethanol, after taking out the gas-phase sample, the headspace is filled with hydrogen, and its methane production rate and ethanol oxidation rate are observed to determine whether an efficient electron transfer channel is formed among the syntrophic microorganisms in the obtained sludge. If the methane production rate and ethanol oxidation rate increase (i.e., the metabolism accelerates), it indicates that an efficient electron transfer channel is formed.

[0052] In some embodiments of the present invention, the hydraulic retention time of the wastewater is 8 - 24 h, specifically it can be 8 h, 12 h, 16 h, 20 h or 24 h. Those skilled in the art can select an appropriate hydraulic retention time according to the water quality of the wastewater.

[0053] In some embodiments of the present invention, the temperature for wastewater treatment is 35 - 37 °C, specifically it can be 35 °C, 36 °C or 37 °C.

[0054] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the accompanying drawings and embodiments. The embodiments of this application are only for illustration. All other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present invention.

[0055] In the following embodiments, the magnetically enhanced anaerobic reactor used is as Figure 2 shown, and the arrangement of the magnetic blocks is as Figure 1 shown, wherein the anaerobic reactor body is an upflow anaerobic sludge bed reactor, its effective volume is 1 L, the inner diameter is 60 mm, and the height is 356 mm; the outer surface of the anaerobic reactor body is provided with 8 rows of magnetic blocks at equal intervals (2 cm), each row of magnetic blocks is provided with 36 magnetic blocks, and the volume of each magnetic block is 1 cm 3 .

[0056] Sludge cultivation:

[0057] The anaerobic granular sludge containing magnetite used in the following embodiments is cultivated through the following steps:

[0058] Prepare synthetic wastewater according to the following component concentrations: the ethanol concentration in the synthetic wastewater is 4.79 g / L; the carbon-nitrogen ratio (mass ratio) is 25:1, and the other substances contained in the synthetic wastewater are: 250 mg / L of K2HPO4, 250 mg / L of KH2PO4, 300 mg / L of MgCl2, 25 mg / L of CaCl2, 15 mg / L of MnCl2, 25 mg / L of FeCl3, 16 mg / L of NiSO4, 25 mg / L of CoCl2, 11.5 mg / L of ZnCl2, 10.5 mg / L of CuCl2, and 0.8 g / g COD of NaHCO3.

[0059] Use a serum bottle with a working volume of 400 mL, add 120 mL of sludge from a sewage treatment plant treating ethanol and citric acid, and 6 g of nanoscale magnetite with a diameter of 30 - 50 nm. Then place the serum bottle in a constant temperature water bath shaker (rotation speed 120 rpm) and culture at 36 °C. When methane production stops (recorded as the first batch of culture), take a gas phase sample, use nitrogen to purge the serum bottle to maintain an anaerobic environment, add ethanol to make the ethanol concentration in the system the same as that in the initial sludge-magnetite mixture, continue to culture until methane production stops (recorded as the second batch of culture), take a gas phase sample, and then repeat the aforementioned step of adding ethanol until methane production stops (recorded as the third batch of culture) to obtain sludge for subsequent wastewater treatment, denoted as "Example Sludge".

[0060] 1. Methane production efficiency of sludge

[0061] Control sludge: Culture sludge using the aforementioned method, with the only difference being that no nanoscale magnetite is added.

[0062] During the culture process, the following modified Gompertz model is used to simulate the maximum methane production potential and the maximum methane production rate during each batch of sludge culture. The results are shown in Table 1.

[0063] P = P max × exp{-exp[R max × e × (λ - t) / P max + 1}

[0064] In the formula, P is the cumulative methane production during the reaction process (mL / gCOD); P max is the maximum production potential of methane gas (mL / gCOD); R max is the maximum production rate of methane gas during the reaction process, (mL / gCOD h); λ is the lag period of the reaction, h, and e is a constant, 2.71828; t is the time when the methane content in the gas bag is measured each time. Among them, P max and R max and λ are obtained by fitting the real data of the sludge culture process.

[0065] Table 1 Methane production rate of each batch of sludge in the examples and the control sludge

[0066]

[0067] As can be seen from the data in Table 1, the methane production efficiency of the sludge in the examples was significantly improved after three batches of cultivation. Among them, the addition of nano-magnetite further promoted the methane production efficiency, which was the largest in the third batch. The methane production potential of the sludge in the examples increased by 10.28% compared with the control sludge, and the maximum methane production rate increased by 29.34%.

[0068] 2. Verify whether an efficient electron transfer channel is formed

[0069] The sludge was cultivated by using the cultivation method of the sludge in the foregoing examples, except that in the third batch of cultivation, after adding ethanol, hydrogen gas (100 mL) was filled into the headspace of the serum bottle at the same time. The remaining amount of ethanol in the system was monitored regularly during the three batches of cultivation.

[0070] Control sludge: The control sludge was cultivated by using this method, except that nano-magnetite was not added. At the same time, the remaining amount of ethanol in the system was monitored regularly during the three batches of cultivation. The monitoring results of the remaining amount of ethanol are shown in Table 2:

[0071] Table 2 Monitoring results of the remaining amount of ethanol

[0072]

[0073] As can be seen from Table 2, with the increase of the cultivation batch, the ability of microorganisms to metabolize ethanol was enhanced. However, when the headspace of the serum bottle was filled with hydrogen gas in the third batch, the change in the ethanol metabolism rate of the control sludge without nano-magnetite was not obvious, and the ethanol metabolism rate of the sludge in the examples with nano-magnetite added was further accelerated. The methane production efficiency and ethanol metabolism rate of the sludge in the examples increased with the increase of the cultivation batch, and maintained a high methane production efficiency and ethanol metabolism rate under the additional hydrogen partial pressure when magnetite was added, indicating that syntrophic microorganisms in the sludge in the examples formed an efficient electron transfer channel at this time.

[0074] Example 1

[0075] This example uses the anaerobic reactor strengthened by the magnetic field shown above Figure 2 to treat simulated wastewater. The difference between the simulated wastewater and the synthetic wastewater is only the ethanol concentration. The ethanol concentration in the simulated wastewater is 2.4 g / L (converted to a COD concentration of 5 g / L).

[0076] The aforementioned anaerobic granular sludge containing magnetite was inoculated into the magnetically enhanced anaerobic reactor (inoculation concentration: 250 mL / L), and then synthetic wastewater was introduced. The temperature of the magnetically enhanced anaerobic reactor was maintained at 37 °C, and wastewater treatment was carried out with a hydraulic retention time of 24 h. When the magnetically enhanced anaerobic reactor operated stably (i.e., the methane production and the total organic carbon (TOC) removal rate were stable for 9 days), a gas chromatograph equipped with a TCD detector was used to detect the methane content, and the oxidation-reduction potential (OPR), ethanol residue, and acetic acid residue in the effluent were measured. Then, the hydraulic retention time was changed to enter the next hydraulic retention time, and the methane production and average oxidation-reduction potential at different hydraulic retention times were tested. The results are shown in Tables 3 - 6 respectively.

[0077] Comparative Example 1

[0078] The aforementioned synthetic wastewater was treated by a method similar to that of Example 1, except that no magnetic blocks were fixed on the outer surface of the anaerobic reactor used, that is, the body of the magnetically enhanced anaerobic reactor in Example 1 (upflow anaerobic sludge bed reactor) was used as the wastewater treatment device. The methane production, average oxidation-reduction potential, ethanol loading, and acetic acid loading at different hydraulic retention times were tested by the method of Example 1. The results are shown in Tables 3 - 6 respectively.

[0079] Table 3 Methane production of Example 1 and Comparative Example 1 at different hydraulic retention times

[0080]

[0081] As can be seen from the results in Table 3, when the hydraulic retention times were 24 h, 20 h, 16 h, 12 h, and 8 h respectively, the methane production of the wastewater treatment method of Example 1 increased by 3.32%, 5.7%, 10.68%, 14.14%, and 13.78 respectively compared with that of the wastewater treatment method of Comparative Example 1.

[0082] Table 4 Liquid phase oxidation-reduction potential of Example 1 and Comparative Example 1 at different hydraulic retention times

[0083] Hydraulic retention time 24h 20h 16h 12h 8h Example 1 (mv) -293.78±10.41 -319.67±2.73 -331.11±2.93 -319.94±2.72 -322.44±3.26 Comparative Example 1 (mv) -273.17±7.12 -277.33±1.80 -300.07±5.46 -289±3.67 -289.83±3.86

[0084] As can be seen from the results in Table 4, at different hydraulic retention times, the oxidation-reduction potential of the wastewater treatment method of Example 1 was significantly lower than that of Comparative Example 1, indicating that the wastewater treatment method of Example 1 converted more kinetic energy into electric potential energy.

[0085] Table 5 Ethanol content in the effluent of Example 1 and Comparative Example 1 at different hydraulic retention times

[0086]

[0087] Table 6 Acetic acid content of Example 1 and Comparative Example 1 at different hydraulic retention times

[0088]

[0089] As can be seen from the results of Table 5 and Table 6, at different hydraulic retention times, the content of organic substances (ethanol and acetic acid) in the treated wastewater of Example 1 is lower, and it is more stable at higher organic loads of 10 g / (L·day) and 15 g / (L·day), indicating that the example can efficiently remove organic substances in water, especially more significantly at high organic loads.

[0090] Although the preferred embodiments of the present invention have been shown and described, it is contemplated that those skilled in the art can design various modifications to the present invention within the spirit and scope of the appended claims.

Claims

1. A magnetic field enhanced anaerobic reactor, comprising an anaerobic reactor body and a plurality of magnetic blocks fixed on the outer surface of the anaerobic reactor body, wherein the plurality of magnetic blocks are divided into a plurality of rows surrounding the outer surface of the anaerobic reactor body, and the magnetic blocks in each row are arranged cyclically in the order of left, top, right, and bottom according to the direction of the magnetic field.

2. The magnetic field enhanced anaerobic reactor according to claim 1, characterized in that: The anaerobic reactor body is an upflow anaerobic sludge blanket reactor.

3. The magnetic field enhanced anaerobic reactor according to claim 1, characterized in that: The magnetic block is an N35 magnetic block.

4. The magnetic field enhanced anaerobic reactor according to any one of claims 1 to 3, characterized in that: The effective volume of the anaerobic reactor body is 1L, the inner diameter is 60mm, and the height is 356mm; the outer surface of the anaerobic reactor body is provided with 8 rows of magnetic blocks at equal intervals, each row of magnetic blocks is provided with 36 magnetic blocks, and the volume of the magnetic blocks is 1cm 3 .

5. A method for recycling wastewater, comprising the following steps: (1) inoculating anaerobic granular sludge containing magnetite into the magnetic field enhanced anaerobic reactor according to any one of claims 1 to 4, (2) introducing wastewater into the magnetic field enhanced anaerobic reactor to treat the wastewater and obtain treated wastewater and methane.

6. The method for recycling wastewater according to claim 5, characterized in that: The inoculation amount of the anaerobic granular sludge containing magnetite is 225-275 mL / L.

7. The wastewater resource treatment method according to claim 5 or 6, characterized in that: The method for preparing the anaerobic granular sludge containing magnetite comprises the following steps: (1) mixing sludge from a sewage treatment plant with nano-magnetite and synthetic wastewater in a ratio of 115-125 mL:6 g:275-285 mL to obtain a sludge-magnetite mixture; wherein the ethanol concentration in the synthetic wastewater is 4.6-4.8 g / L, and the carbon-nitrogen ratio is 20-26:1; (2) The sludge-magnetite mixture is cultured at 35-37° C. When methane can no longer be produced, ethanol is added to make the ethanol concentration in the system the same as the ethanol concentration in the initial sludge-magnetite mixture, and the culture is continued until methane can no longer be produced. Then, the aforementioned step of adding ethanol is repeated, and the culture is continued until methane can no longer be produced, thereby obtaining anaerobic granular sludge containing magnetite.

8. The method for recycling wastewater according to claim 7, characterized in that: The diameter of the nano magnetite is 30-50nm; The synthetic wastewater includes substances in the following concentrations: 250 mg / L K2HPO4, 250 mg / L KH2PO4, 300 mg / L MgCl2, 25 mg / L CaCl2, 15 mg / L MnCl2, 25 mg / L FeCl3, 16 mg / L NiSO4, 25 mg / L CoCl2, 11.5 mg / L ZnCl2, 10.5 mg / L CuCl2, and 0.8 g / g COD NaHCO3.

9. The wastewater resource treatment method according to claim 5 or 6, characterized in that: The hydraulic retention time of the wastewater is 8-24h.

10. The method for recycling wastewater according to claim 5 or 6, characterized in that: The temperature of the wastewater treatment is 35-37°C.

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