Sulfur autotrophic denitrification filter material enhanced constructed wetland microbial fuel cell sewage treatment system and treatment method

Abstract

The invention discloses a sulfur autotrophic denitrification filter material enhanced constructed wetland microbial fuel cell sewage treatment system and method, and the treatment system comprises a container main body, the container main body sequentially comprises a gravel water distribution layer, a granular activated carbon anode layer, a sulfur autotrophic denitrification filter material layer, a middle gravel layer, a granular activated carbon cathode layer and a wetland plant layer from bottom to top, anodes are embedded in the granular activated carbon anode layer, cathodes are embedded in the granular activated carbon cathode layer, and the wetland plant layer is arranged in the middle gravel layer. A lead penetrates through the granular activated carbon anode layer and the granular activated carbon cathode layer to connect the anode with the cathode, a water inlet is formed in the gravel water distribution layer, and a water outlet is formed in the wetland plant layer. The constructed wetland microbial fuel cell and the sulfur autotrophic denitrification technology are combined, the dual effects of pollutant removal and electric energy generation are achieved, a new thought is provided for combination of the constructed wetland microbial fuel cell and the sulfur autotrophic denitrification technology, and meanwhile, a new direction is provided for removal of river sewage.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to a sulfur autotrophic denitrification filter material enhanced artificial wetland microbial fuel cell sewage treatment system and a treatment method. Background Art

[0002] Constructed wetland (CWs) treatment technology is a comprehensive ecosystem for treating sewage. It is a controllable ecological sewage treatment technology that is artificially constructed and controlled based on the imitation of natural wetlands. CWs mainly treat sewage through plant absorption, adsorption, precipitation, microbial degradation, etc., to achieve efficient sewage purification and treatment, and are widely used in ecological governance and restoration. Microbial fuel cells convert organic matter in pollutants into electrical energy through microorganisms, using microorganisms as biocatalysts to produce electrons through anaerobic oxidation of energy-rich organic matter. As an emerging sewage treatment technology, microbial fuel cells have the advantages of both pollutant treatment and electricity generation, and have good development prospects.

[0003] The traditional artificial wetlands have low efficiency in removing pollutants. The main reason is that the availability of suitable electron acceptors is insufficient in most artificial wetlands, which hinders the effective oxidation of pollutants and causes air not to diffuse deep into artificial wetlands. Sulfur autotrophic denitrification is a process in which sulfur is used as the electron donor for denitrification and nitrate is used as the electron acceptor to convert nitrate into nitrogen gas under the action of sulfur autotrophic denitrifying bacteria in an anaerobic environment. Compared with the traditional biological denitrification process, sulfur autotrophic denitrification technology has received widespread attention at home and abroad because it does not require an external carbon source, has low sludge production, and is low in cost. It has also been well applied in many aspects. However, there are few studies on combining sulfur autotrophic denitrification and artificial wetland-microbial fuel cell treatment methods to treat sewage. Based on this, the present invention patent is proposed. Summary of the invention

[0004] In order to overcome the above defects of the prior art, the present invention provides a sulfur autotrophic denitrification filter material enhanced artificial wetland microbial fuel cell sewage treatment system and treatment method to solve the problems raised in the above background technology.

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

[0006] A sulfur autotrophic denitrification filter material enhanced artificial wetland microbial fuel cell sewage treatment system comprises a container body, wherein the container body comprises, from bottom to top, a gravel water distribution layer, a granular activated carbon anode layer, a sulfur autotrophic denitrification filter material layer, an intermediate gravel layer, a granular activated carbon cathode layer and a wetland plant layer, an anode is buried in the granular activated carbon anode layer, a cathode is buried in the granular activated carbon cathode layer, a wire passes through the granular activated carbon anode layer and the granular activated carbon cathode layer to connect the anode and the cathode, a water inlet is arranged in the gravel water distribution layer, and a water outlet is arranged in the wetland plant layer.

[0007] Furthermore, a resistor is arranged between the wires connecting the anode and the cathode.

[0008] Furthermore, one end of the water inlet is connected to the peristaltic pump and the waste water bucket through a water pipe.

[0009] Furthermore, the anode and cathode are made of activated carbon particles wrapped in a stainless steel mesh, and the stainless steel mesh has 12 meshes.

[0010] Furthermore, the particle size of the gravel water distribution layer is 30-50 mm, the particle size of the intermediate gravel layer is 10-20 mm, the particle size of the granular activated carbon anode layer is 3-5 mm, the particle size of the sulfur autotrophic denitrification filter material layer is 3-5 mm, and the particle size of the granular activated carbon cathode layer is 3-5 mm.

[0011] Furthermore, the thickness of the gravel water distribution layer is 15-25 cm, the thickness of the granular activated carbon anode layer is 5-8 cm, the thickness of the sulfur autotrophic denitrification filter material layer is 5-8 cm, the thickness of the middle gravel layer is 15-25 cm, and the thickness of the granular activated carbon cathode layer is 5-8 cm.

[0012] Furthermore, the container body is a cylinder with a diameter not less than 200 mm.

[0013] Furthermore, the thickness ratio of the gravel water distribution layer, the granular activated carbon anode layer, the sulfur autotrophic denitrification filter material layer, the intermediate gravel layer, and the granular activated carbon cathode layer is 3:1:1:3:1

[0014] The present invention also provides a method for treating wastewater in a sulfur autotrophic denitrification filter material-enhanced artificial wetland microbial fuel cell wastewater treatment system, comprising the following steps:

[0015] (1) The domestic sewage is introduced from the water inlet, and the domestic sewage flows through the gravel water distribution layer, the granular activated carbon anode layer, the sulfur autotrophic denitrification filter layer, the intermediate gravel layer and the granular activated carbon cathode layer in sequence;

[0016] (2) When microorganisms decompose organic matter to release electrons and protons, the electrons at the anode of the granular activated carbon anode layer are conducted to the buried cathode of the granular activated carbon cathode layer through the wire, forming an electric current;

[0017] (3) After several days of circulation treatment, the purified sewage is discharged from the outlet.

[0018] The present invention stratifies the artificial wetland into a bottom anaerobic area and a top aerobic area through a container body, forming a gradually increasing redox gradient from the bottom to the top, and providing conditions for the combination of microbial fuel cells and artificial wetlands.

[0019] By setting a cathode at the aerobic area at the top of the device and an anode at the anaerobic area at the bottom, connected by external wires, the anode oxidizes and degrades organic matter into inorganic matter, electrons, and hydrogen ions through the action of microorganisms; the electrons are transferred to the cathode through the wires, and the cathode reacts oxygen, electrons, and hydrogen ions in the aerobic area to generate water. In this process, the device not only effectively removes pollutants, but also generates electricity. It is a new green sewage treatment technology that combines artificial wetlands and microbial fuel cells, called artificial wetland microbial fuel cells.

[0020] In the sulfur autotrophic denitrification-constructed wetland-microbial fuel cell of the present invention, the electrons generated by the microbial fuel cell can accelerate the treatment of sewage by sulfur autotrophic denitrification. The device combines sulfur autotrophic denitrification with artificial wetland microbial biofuel cells to achieve efficient treatment of river sewage.

[0021] The beneficial effects of the present invention relative to the prior art are:

[0022] (1) The present invention combines artificial wetland microbial fuel cells with sulfur autotrophic denitrification technology to achieve the dual effects of pollutant removal and electricity generation, providing a new idea for the combination of artificial wetland microbial fuel cells and sulfur autotrophic denitrification technology, and also providing a new direction for river sewage removal.

[0023] (2) Compared with the traditional artificial wetland microbial fuel cell device for treating sewage, the present invention combines sulfur autotrophic denitrification with artificial wetland microbial fuel cells, and detects the pollutant removal effect of the pollutant concentration monitoring device, detects the power generation performance of the voltage monitoring device, and enhances the artificial wetland microbial fuel cell's ability to remove nitrogen from the water body through sulfur autotrophic denitrification technology, thereby achieving the removal of pollutants in sewage while generating electricity.

[0024] (3) The present invention adds fuel cells based on the conditions of artificial wetlands. The oxygen-consuming and anaerobic areas in artificial wetlands provide a natural potential difference for fuel cells, that is, they provide a place for the oxygen-consuming reaction stage and the anaerobic reaction stage of fuel cells. In addition, wetland fuel cells do not require ion exchange membranes, and the cost is lower than that of fuel cells. Compared with fuel cells, wetland microbial fuel cells have more application scenarios, more types of pollutants removed, and increased microbial richness of microbial fuel cells. This solves the problem that river sewage has a high fluidity, a low degree of pollution, and is difficult to achieve deep removal, and has a high nitrogen content. The traditional river has a low nitrogen removal effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the sulfur autotrophic denitrification filter material enhanced artificial wetland microbial fuel cell sewage treatment system of the present invention;

[0026] Figure 2 The sulfur autotrophic denitrification filter material of the sewage treatment system of Example 1 was used to strengthen the artificial wetland microbial fuel cell sewage treatment system for river water CODcr, TN, TP, NH4 + -N、NO3 - -N test results;

[0027] Figure 3 The test result of the voltage under the river water treated by the sulfur autotrophic denitrification filter material enhanced artificial wetland microbial fuel cell sewage treatment system of Example 1;

[0028] Figure 4 The power density and polarization curve of the sulfur autotrophic denitrification filter material-enhanced artificial wetland microbial fuel cell sewage treatment system of the sewage treatment system of Example 1;

[0029] Figure 1 Figure numerals: 1. wastewater barrel, 2. peristaltic pump, 3. water pipe, 4. water inlet, 5. gravel water distribution layer, 6. granular activated carbon anode layer, 7. anode, 8. sulfur autotrophic denitrification filter material layer, 9. intermediate gravel layer, 10. cathode, 11. granular activated carbon cathode layer, 12. wetland plant layer, 13. water outlet, 14. wire, 15. resistor. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The following is combined with Figure 1 The present invention is described in detail. A sulfur autotrophic denitrification filter material enhanced artificial wetland microbial fuel cell sewage treatment system includes a container body, and the container body includes a gravel water distribution layer 5, a granular activated carbon anode layer 6, a sulfur autotrophic denitrification filter material layer 8, an intermediate gravel layer 9, a granular activated carbon cathode layer 11 and a wetland plant layer 12 from bottom to top. An anode 7 is buried in the granular activated carbon anode layer 6, and a cathode 10 is buried in the granular activated carbon cathode layer 11. A wire 14 passes through the granular activated carbon anode layer 6 and the granular activated carbon cathode layer 11 to connect the anode 7 and the cathode 10. A water inlet 4 is set in the gravel water distribution layer 5, and a water outlet 13 is set in the wetland plant layer 12.

[0032] In one embodiment, a resistor 15 is disposed between the wire 14 connecting the anode 7 and the cathode 10 .

[0033] In one embodiment, one end of the water inlet 4 is connected to the peristaltic pump 2 and the waste water bucket 1 through a water pipe 3 .

[0034] In one embodiment, the anode 7 and the cathode 10 are made of activated carbon particles wrapped in a stainless steel mesh, and the stainless steel mesh has 12 meshes.

[0035] In one embodiment, the particle size of the gravel water distribution layer 5 is 30-50 mm, the particle size of the intermediate gravel layer 9 is 10-20 mm, the particle size of the granular activated carbon anode layer 6 is 3-5 mm, the particle size of the sulfur autotrophic denitrification filter material layer 8 is 3-5 mm, and the particle size of the granular activated carbon cathode layer 11 is 3-5 mm.

[0036] In one embodiment, the thickness of the gravel water distribution layer 5 is 15-25 cm, the thickness of the granular activated carbon anode layer 6 is 5-8 cm, the thickness of the sulfur autotrophic denitrification filter material layer 8 is 5-8 cm, the thickness of the intermediate gravel layer 9 is 15-25 cm, and the thickness of the granular activated carbon cathode layer 11 is 5-8 cm.

[0037] In one embodiment, the container body is a cylinder with a diameter not less than 200 mm.

[0038] In one embodiment, the thickness ratio of the gravel water distribution layer 5, the granular activated carbon anode layer 6, the sulfur autotrophic denitrification filter material layer 8, the intermediate gravel layer 9, and the granular activated carbon cathode layer 11 is 3:1:1:3:1

[0039] The present invention also provides a method for treating wastewater in a sulfur autotrophic denitrification filter material-enhanced artificial wetland microbial fuel cell wastewater treatment system, comprising the following steps:

[0040] (1) Domestic sewage is introduced from the water inlet 4, and the domestic sewage flows through the gravel water distribution layer 5, the granular activated carbon anode layer 6, the sulfur autotrophic denitrification filter layer 8, the intermediate gravel layer 9 and the granular activated carbon cathode layer 11 in sequence;

[0041] (2) When microorganisms decompose organic matter to release electrons and protons, the electrons of the anode 7 of the granular activated carbon anode layer 6 are conducted to the cathode 10 buried in the granular activated carbon cathode layer 11 through the wire 4, forming an electric current;

[0042] (3) After circulating for several days, the purified sewage is discharged from the outlet 13.

[0043] Example 1

[0044] A sulfur autotrophic denitrification artificial wetland microbial fuel cell, the container body is a single-layer cylindrical barrel, the bottom of the barrel is provided with a water inlet 4, the top side wall is provided with a water outlet 13, the water inlet 4 and the water outlet 13 have a diameter of 20 mm, the inner barrel is provided with a gravel water distribution layer 5, a granular activated carbon anode layer 6, a sulfur autotrophic denitrification filter material layer 8, an intermediate gravel layer 9, a granular activated carbon cathode layer 11 and a wetland plant layer 12 from bottom to top, an anode 7 is buried in the granular activated carbon anode layer 6, a cathode 10 is buried in the granular activated carbon cathode layer 11, a wire 14 is connected to the cathode 10, and the wire 14 is connected to the anode 7 via a resistor 15.

[0045] The gravel water distribution layer 5 is composed of gravels with a particle size of 30-50 mm and a height of 15 cm; the granular activated carbon anode layer 6 and the granular activated carbon cathode layer 11 are composed of granular activated carbon with a particle size of 3-5 mm and a 12-mesh stainless steel mesh, and are both 5 cm high; the sulfur autotrophic denitrification filter material layer 8 is composed of sulfur autotrophic denitrification filter material with a particle size of 3-5 mm and a height of 5 cm; the middle gravel layer 9 is composed of gravels with a particle size of 10-20 mm and a height of 15 cm; the wetland plant layer 12 above the cathode 10 is planted with plant milk canna, and the planting density is 10-20 plants / m -2 .

[0046] The electrodes of the anode 7 and the cathode 10 are composed of a stainless steel mesh and granular activated carbon. The wire 14 is a copper wire and the connection between the electrodes of the anode 7 and the cathode 10 is coated with epoxy resin to avoid direct contact between the interface and the water body during operation and to avoid short circuit. The microorganisms are mainly attached to the electrodes of the anode 7 and the cathode 10 and the sulfur autotrophic denitrification filter layer.

[0047] The surface of the device of the present invention is wrapped with black cloth for dark treatment, the purpose of which is to prevent algae from growing and affecting the treatment efficiency of the device.

[0048] The peristaltic pump 2 takes water from the artificial simulated wastewater barrel 1 through the water inlet 4, passes through the gravel water distribution layer 5, the granular activated carbon anode layer 6, the sulfur autotrophic denitrification filter material layer 8, the intermediate gravel layer 9, and the granular activated carbon cathode layer 11, forming a vertical upflow operation mode. Plants are planted on the top of the granular activated carbon cathode layer 11, and the hydraulic retention time is set to 3 days to remove pollutants from the river water and generate electricity.

[0049] Application testing:

[0050] The wastewater treatment system of the sulfur autotrophic denitrification artificial wetland microbial fuel cell of Example 1 was used to treat wastewater, and the pollutant removal efficiency and power generation effect of the sulfur autotrophic denitrification artificial wetland microbial fuel cell unit of the wastewater treatment system were tested.

[0051] The pollutant removal efficiency and power generation effect of the sulfur autotrophic denitrification artificial wetland microbial fuel cell unit of the sewage treatment system of Example 1 were tested.

[0052] Experimental methods

[0053] The sulfur autotrophic denitrification artificial wetland microbial fuel cell device was started to treat the sewage. The river sewage (COD 50mg / L, TN 6mg / L, TP 1mg / L, NH4 + -N 3mg / L, NO3 - -N 3mg / L) is introduced from the water inlet of the main body of the sulfur autotrophic denitrification artificial wetland microbial fuel cell, and the domestic sewage flows through the gravel water distribution layer 5, the granular activated carbon anode layer 6, the sulfur autotrophic denitrification filter material layer 8, the intermediate gravel layer 9, and the granular activated carbon cathode layer 11 in sequence. At the anode 7, microorganisms decompose organic matter to release electrons and protons, and the electrons are conducted to the cathode 10 through the external circuit to form an electric current. After the sewage is purified, it flows out from the top outlet 13 on one side of the main body of the microbial fuel cell artificial wetland. Tests were conducted at influent concentrations of COD 50mg / L, TN 6mg / L, TP1mg / L, NH4 + -N 3mg / L, NO3 - -N 3mg / L concentration, HRT = 3d, CODcr, TN, TP, NH4 + -N、NO3 - -N removal rate, the detection time is 60 days, the power generation voltage of the sulfur autotrophic denitrification artificial wetland microbial fuel cell device is tested, and the maximum power density and open circuit voltage of the device are determined by changing the resistance value of the external resistor.

[0054] Figure 2 COD, TN, TP, NH4 + -N、NO3 --N removal rate test results: influent concentration COD 50mg / L, TN 6mg / L, TP 1mg / L, NH4 + -N 3mg / L, NO3 - -N 3mg / L concentration, HRT = 3d when CODcr, TN, TP, NH4 + -N、NO3 - The average removal rates of -N were 81.1%, 79.5%, 82.2%, 76.12% and 66.78%. Figure 3 The results of the voltage change process over time show that the device voltage gradually increases and eventually stabilizes, and the average voltage of the device is 210mV. Figure 4 The polarization curve and power density curve were drawn based on the voltage obtained by changing the resistance value of the external resistor. The results showed that the maximum power density was 392.5mW / ㎡ and the open circuit voltage was 163.1mV.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A sulfur autotrophic denitrification filter material enhanced artificial wetland microbial fuel cell sewage treatment system, comprising a container body, characterized in that: The container body comprises, from bottom to top, a gravel water distribution layer (5), a granular activated carbon anode layer (6), a sulfur autotrophic denitrification filter material layer (8), an intermediate gravel layer (9), a granular activated carbon cathode layer (11) and a wetland plant layer (12); an anode (7) is buried in the granular activated carbon anode layer (6), a cathode (10) is buried in the granular activated carbon cathode layer (11); a wire (14) penetrates the granular activated carbon anode layer (6) and the granular activated carbon cathode layer (11) to connect the anode (7) and the cathode (10); a water inlet (4) is arranged in the gravel water distribution layer (5), and a water outlet (13) is arranged in the wetland plant layer (12).

2. According to claim 1, a sulfur autotrophic denitrification filter material enhanced artificial wetland microbial fuel cell wastewater treatment system is characterized in that: A resistor (15) is arranged between the wire (14) connecting the anode (7) and the cathode (10).

3. According to claim 1, a sulfur autotrophic denitrification filter material enhanced artificial wetland microbial fuel cell wastewater treatment system is characterized in that: One end of the water inlet (4) is connected to the peristaltic pump (2) and the waste water bucket (1) via a water pipe (3).

4. According to claim 1, a sulfur autotrophic denitrification filter material enhanced artificial wetland microbial fuel cell wastewater treatment system is characterized in that: The anode (7) and cathode (10) are made of activated carbon particles wrapped in stainless steel mesh.

5. According to claim 1, a sulfur autotrophic denitrification filter material enhanced artificial wetland microbial fuel cell wastewater treatment system is characterized in that: The particle size of the gravel water distribution layer (5) is 30-50 mm, the particle size of the intermediate gravel layer (9) is 10-20 mm, the particle size of the granular activated carbon anode layer (6) is 3-5 mm, the particle size of the sulfur autotrophic denitrification filter material layer (8) is 3-5 mm, and the particle size of the granular activated carbon cathode layer (11) is 3-5 mm.

6. According to claim 1, a sulfur autotrophic denitrification filter material enhanced artificial wetland microbial fuel cell wastewater treatment system is characterized in that: The thickness of the gravel water distribution layer (5) is 15-25 cm, the thickness of the granular activated carbon anode layer (6) is 5-8 cm, the thickness of the sulfur autotrophic denitrification filter material layer (8) is 5-8 cm, the thickness of the intermediate gravel layer (9) is 15-25 cm, and the thickness of the granular activated carbon cathode layer (11) is 5-8 cm.

7. According to claim 1, a sulfur autotrophic denitrification filter material enhanced artificial wetland microbial fuel cell wastewater treatment system is characterized in that: The container body is a cylinder with a diameter not less than 200 mm.

8. The sulfur autotrophic denitrification filter material enhanced artificial wetland microbial fuel cell wastewater treatment system according to claim 1, characterized in that: The thickness ratio of the gravel water distribution layer (5), the granular activated carbon anode layer (6), the sulfur autotrophic denitrification filter material layer (8), the intermediate gravel layer (9), and the granular activated carbon cathode layer (11) is 3:1:1:3:

1.

9. The method for treating wastewater in a sulfur autotrophic denitrification filter material-enhanced constructed wetland microbial fuel cell system according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) introducing domestic sewage from a water inlet (4), and the domestic sewage sequentially flows through a gravel water distribution layer (5), a granular activated carbon anode layer (6), a sulfur autotrophic denitrification filter layer (8), an intermediate gravel layer (9), and a granular activated carbon cathode layer (11); (2) When microorganisms decompose organic matter to release electrons and protons, the electrons of the anode (7) of the granular activated carbon anode layer (6) are conducted to the buried cathode (10) of the granular activated carbon cathode layer (11) through the wire (4), thereby forming an electric current; (3) After several days of circulation treatment, the purified sewage is discharged from the outlet (13).

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