CN112062271A - Bio-electrochemical reaction device and method for denitrifying anaerobic methane oxidation film - Google Patents

Abstract

The invention discloses a denitrification anaerobic methane oxidation film bioelectrochemical reaction device and a method thereof, wherein the device comprises a closed cylinder, and a cathode and an anode which are positioned in the inner cavity of the cylinder, wherein the cathode and the anode are respectively communicated with the cathode and the anode of an external power supply through leads; the anode comprises a titanium mesh, granular activated carbon and an MBR (membrane bioreactor) membrane component, and the titanium mesh wraps the granular activated carbon on the surface of the MBR membrane component; the surfaces of the granular activated carbon and the MBR membrane component are used for enriching denitrifying anaerobic methane oxidation microorganisms; the cathode is a carbon felt with the surface used for enriching autotrophic denitrifying microorganisms; the inner cavity of the cylinder body below the anode and the cathode is provided with water distribution pipes with uniform holes, and a gas distributor is arranged below the water distribution pipes. The invention realizes the cooperative removal of nitrate and methane in the wastewater treatment process by coupling the bioelectrochemical system, the membrane component and the denitrification anaerobic methane oxidation microorganism, and has the characteristics of high efficiency, low cost, low energy consumption and small space.

Description

A denitrifying anaerobic methane oxidation membrane bioelectrochemical reaction device and method thereof

technical field

The invention belongs to the field of biological wastewater treatment, and in particular relates to a denitrification anaerobic methane oxidation membrane bioelectrochemical reaction device and a method thereof.

Background technique

The traditional nitrification-denitrification process for biological denitrification of wastewater has insufficient electron donors in the denitrification section, which restricts the denitrification efficiency. At the same time, a large amount of methane is generated in the anaerobic digestion section, which is dissolved in water and finally discharged and released with the wastewater. It is one of the main causes of the global greenhouse effect, and it is also a waste of resources.

SUMMARY OF THE INVENTION

Aiming at the problems of incomplete denitrification process and disorderly discharge of generated methane in urban wastewater treatment, the invention provides a denitrification anaerobic methane oxidation membrane bioelectrochemical reaction device and a method thereof.

The technical scheme specifically adopted in the present invention is as follows:

A denitrification anaerobic methane oxidation membrane bioelectrochemical reaction device, which comprises a closed cylinder, a cathode and an anode located in the inner cavity of the cylinder, and the cathode and the anode are respectively connected with the negative and positive electrodes of an external power supply through wires;

The anode includes a titanium mesh, granular activated carbon and an MBR membrane module, and the titanium mesh wraps the granular activated carbon on the surface of the MBR membrane module; the surfaces of the granular activated carbon and the MBR membrane module are both used for enriching denitrifying anaerobic methane oxidation microorganisms, and the titanium mesh The titanium wire is externally connected and communicated with the wire, and the outlet end of the MBR membrane module is communicated with the outside through a water outlet pipe provided with an outlet pump; the cathode is a carbon felt whose surface is used to enrich autotrophic denitrifying microorganisms;

The inner cavity of the cylinder under the anode and the cathode is provided with a water distribution pipe with uniform openings, and a gas distributor is arranged under the water distribution pipe; the air inlet end of the gas distributor is connected to the outside, and is used to blow air to the anode to make the granular activated carbon flow. A gas outlet is provided on the side wall of the upper part of the cylinder, and the gas outlet is communicated with the gas inlet end of the gas distributor through a gas pipeline provided with a circulating pump.

Preferably, the opening rate of the water distribution pipe is 10%, and the water distribution pipe located outside the cylinder is provided with an inlet pump.

Preferably, the gas distributor is a disc type distributor, and an aeration pump is provided at the air inlet end outside the cylinder.

Preferably, a sampling port is provided on the side wall of the cylinder close to the anode.

Preferably, the mesh opening of the titanium mesh is a diamond mesh opening, and the short diagonal length thereof is 1 mm.

Preferably, the material of the MBR membrane module is polyvinylidene fluoride PVDF.

Preferably, a voltage sensor and an alarm are connected in series to the wire and connected in parallel with a resistance of 500-1000Ω, so as to monitor the voltage state of the reaction device in real time.

Preferably, the granular activated carbon is spherical particles with an average particle size of 2 mm; the filling degree of the granular activated carbon on the surface of the MBR membrane module is 20%.

Another object of the present invention is to provide a method for treating nitrate waste water and methane waste gas according to any of the above-mentioned reaction devices, which is specifically as follows:

Turn on the water inlet pump, and pass the nitrate waste water into the inner cavity of the cylinder through the water distribution pipe and realize uniform distribution; at the same time, open the aeration pump, pass the methane waste gas into the inner cavity of the cylinder through the gas distributor and make it fully contact with the waste water, and the methane gas dissolves in wastewater;

Turn off the aeration pump and turn on the circulation pump; through the action of the circulation pump, the methane gas at the top of the cylinder that is not dissolved with the waste water is re-suctioned to the intake end of the gas distributor to realize the recycling of methane gas; by controlling the circulation pump to Adjust the flow rate of methane gas to make granular activated carbon fluidized;

Nitrate in wastewater and methane dissolved in water are simultaneously converted into nitrogen and carbon dioxide by denitrifying anaerobic methane-oxidizing microorganisms enriched on the surface of granular activated carbon and MBR membrane modules. At the same time, the generated electrons are transferred to granular activated carbon, using biological Electrochemical promotion improves the activity of denitrifying anaerobic methane oxidation microorganisms; the generated electrons are transferred from the granular activated carbon to the titanium mesh through the collision between the granular activated carbon and the titanium mesh, and then transferred to the carbon felt through the external titanium wire through the wire ; Autotrophic denitrifying microorganisms enriched on the surface of carbon felt use electrons to further reduce nitrate in water to nitrogen;

The voltage state of the reaction device is monitored in real time by a voltage sensor arranged on the wire; when the voltage deviates from a predetermined value, an alarm connected in series with the voltage sensor will issue an alarm.

Preferably, the waste water passed into the cylinder accounts for 3/4 of the volume of the inner cavity of the cylinder.

Compared with the prior art, the present invention has the following beneficial effects:

1) In the reaction device of the present invention, the synergistic removal of nitrate and methane in the wastewater treatment process is realized through the coupling of the bioelectrochemical system, the membrane module and the denitrifying anaerobic methane oxidizing microorganism;

2) The reaction device of the present invention converts nitrate-type waste water and excess methane produced during waste water treatment into nitrogen gas and carbon dioxide, thereby realizing the effect of simultaneous denitrification and carbon removal in waste water treatment;

3) The reaction device of the present invention has the characteristics of high efficiency, low cost, low energy consumption and small space.

Description of drawings

Fig. 1 is the structural representation of the reaction device of the present invention;

In the figure: outlet pump 1, air outlet 2, sampling port 3, circulating pump 4, inlet pump 5, water inlet 6, water distribution pipe 7, gas distributor 8, air inlet 9, aeration pump 10, granular activated carbon 11, MBR membrane assembly 12 , titanium mesh 13 , titanium wire 14 , voltage sensor 15 , resistor 16 , alarm 17 , wire 18 , carbon felt 19 , anode area 20 , cathode area 21 .

Detailed ways

The present invention will be further elaborated and described below with reference to the accompanying drawings and specific embodiments. The technical features of the various embodiments of the present invention can be combined correspondingly on the premise that there is no conflict with each other.

As shown in FIG. 1 , it is a denitrification anaerobic methane oxidation membrane bioelectrochemical reaction device of the present invention. The reaction device includes a closed cylindrical cylinder and an anode area 20 and a cathode area 21 located in the inner cavity of the cylinder. Through the optimization of the process, the present invention enables the nitrates in the wastewater and the methane produced in the wastewater treatment to be synergistically treated by the nitrifying anaerobic methane oxidizing microorganisms and the autotrophic denitrifying microorganisms. The specific implementation of each structure is described in detail below:

The main body of the anode region 20 is the anode, and the anode includes the titanium mesh 13 , the granular activated carbon 11 and the MBR membrane module 12 , and the titanium mesh 13 wraps the granular activated carbon 11 on the surface of the MBR membrane module 12 . It should be noted that this wrapping state is not to tightly wrap the granular activated carbon 11 on the surface of the MBR membrane module 12, but only to limit the position, that is, the surface of the granular activated carbon 11 and the MBR membrane module 12 There is a certain space between them, and the granular activated carbon 11 can move in this space to achieve a fluidized state. The filling degree of the granular activated carbon 11 on the surface of the MBR membrane module 12 is 20%.

The surfaces of granular activated carbon 11 and MBR membrane module 12 are both used to enrich denitrifying anaerobic methane oxidizing microorganisms, and nitrate and methane are removed by the action of nitrifying anaerobic methane oxidizing microorganisms. Granular activated carbon 11 adopts spherical particles with an average particle size of 2 mm. . Since the growth rate of microorganisms is slow and the activity is low, it is necessary to set the MBR membrane module 12 at the anode to trap the microorganisms for increasing the growth rate of the microorganisms, and to set the bioelectrochemical system to increase the activity of the microorganisms. The material of the MBR membrane module 12 used in this embodiment is polyvinylidene fluoride PVDF. Due to the membrane fouling problem of the MBR membrane module 12 , the granular activated carbon 11 is surrounded around the MBR membrane module 12 for adsorbing excess microorganisms in the MBR membrane module 12 . The top of the MBR membrane module 12 in the anode is connected to the effluent pump 1 . In order to make the promotion effect of the bioelectrochemical system more efficient, the titanium mesh 13 of the anode is surrounded by all sides and the top is open, and the granular activated carbon 11 is completely enclosed. The titanium mesh 13 used in this embodiment is a diamond-shaped mesh port, and the shortest diagonal distance is 1 mm. In the actual application process, the specific size of the MBR membrane assembly 12 and the titanium mesh 13 can be determined according to the actual volume of the device.

The cathode is a carbon felt 19 whose surface is used to enrich autotrophic denitrifying microorganisms. The cathode and the anode are respectively connected with the negative electrode and the positive electrode of the external power supply through the wire 18, and work together to realize the simultaneous removal of nitrate and methane in the wastewater.

A water distribution pipe 7 with uniform openings is arranged in the inner cavity of the cylinder below the anode and the cathode, and a gas distributor 8 is arranged below the water distribution pipe 7 . An inlet pump 5 is provided on the water distribution pipe 7 located outside the cylinder to provide power for the waste water to enter the inner cavity of the cylinder. In this embodiment, the inlet pump 5 is a peristaltic pump. The water inlet conduit 7 traverses the entire reaction device, and the pores are designed uniformly, and the porosity of the water distribution pipe 7 is preferably 10%, so that the water inlet is more uniform.

The gas distributor 8 is a disc type distributor, so that methane can enter more uniformly, and an aeration pump 10 is provided at the air inlet end of the gas distributor 8 outside the cylinder. The air inlet end of the gas distributor 8 communicates with the outside through the air inlet 9 opened at the bottom of the cylinder, and is used for blowing air to the anode to realize the fluidized state of the granular activated carbon 11 . The side wall of the upper part of the cylinder is provided with an air outlet 2, and the air outlet 2 is communicated with the air inlet end of the gas distributor 8 through a gas pipeline provided with a circulating pump 4, and is used for dissolving the methane gas at the top of the cylinder body that is not dissolved in water. It is sucked to the intake end of the gas distributor 8, so as to realize the recycling of methane gas. In the initial stage of the reaction, the methane is pumped to the air inlet 9 through the aeration pump 10, and then the methane is evenly transported into the inner cavity of the cylinder through the gas distributor 8, so as to facilitate the subsequent co-processing of water and gas. After the aeration is completed, the aeration pump 10 is turned off and the circulation pump 4 is turned on. Due to the low solubility of methane in water, the excess methane above the device is circulated from the air inlet 2 to the inner cavity of the cylinder through the circulating pump 4 to improve the availability of methane. At the same time, the methane is controlled by adjusting the circulating pump 4 in this process The flow rate of the gas makes the granular activated carbon 11 of the anode in a fluidized state.

In addition, the external circuit area 22 is provided with a voltage sensor 15 and an alarm 17. The voltage sensor 15 monitors the voltage generated in real time. When the voltage deviates from a predetermined value, the alarm 17 will issue an alarm to indicate that the device is not functioning properly. A voltage sensor 15 is connected in series with an alarm 17, both of which are connected in parallel with a resistor 16 of size 500-1000Ω. At the same time, a sampling port 3 is provided on the middle wall of the device near the anode side, and various parameters of the effluent are monitored at any time.

In the present invention, the coupling of the bioelectrochemical system, the membrane module and the denitrifying anaerobic methane oxidizing microorganism realizes the synergistic removal of nitrate and methane in the wastewater treatment process. Through the double optimization of process and treatment methods, nitrate-type wastewater and excess methane generated during wastewater treatment are converted into nitrogen and carbon dioxide to achieve the effect of simultaneous denitrification and carbon removal in wastewater treatment.

Therefore, based on the above-mentioned reaction device, the present invention also provides a method for processing nitrate waste water and methane waste gas, which is specifically as follows:

First, the inlet water pump 5 is turned on, and the nitrate waste water is passed through the water distribution pipe 7 into the inner cavity of the cylinder to achieve uniform distribution. According to the calculation of chemical reaction stoichiometry and Henry's law of gas dissolution, the waste water passed into the cylinder accounts for 3/4 of the cavity volume of the cylinder. At the same time, the aeration pump 10 is turned on, and the methane waste gas is passed into the inner cavity of the cylinder through the gas distributor 8 to make it fully contact with the waste water, and the methane gas is dissolved in the waste water.

Then, the aeration pump 10 is turned off, and the circulation pump 4 is turned on. Through the action of the circulating pump 4, the methane gas that is not dissolved with the waste water at the top of the inner cavity of the cylinder is re-suctioned to the intake end of the gas distributor 8, so as to realize the recycling of the methane gas. The flow rate of the methane gas is adjusted by controlling the circulating pump 4, so that the granular activated carbon 11 is fluidized.

During this period, the nitrates in the wastewater and the methane dissolved in the water are simultaneously converted into nitrogen and carbon dioxide by the denitrifying anaerobic methane-oxidizing microorganisms enriched on the surface of the granular activated carbon 11 and the MBR membrane module 12 . At the same time, the generated electrons are transferred to the granular activated carbon 11, and the activity of the denitrifying anaerobic methane oxidizing microorganisms is improved by the promoting effect of bioelectrochemistry. The generated electrons are transmitted from the granular activated carbon 11 to the titanium mesh 13 through the collision between the granular activated carbon 11 and the titanium mesh 13 , and then transmitted to the carbon felt 19 through the external titanium wire 14 through the wire 18 . The autotrophic denitrifying microorganisms enriched on the surface of carbon felt 19 use this part of the electrons to further reduce nitrate in water to nitrogen gas.

During the operation of the device of the present invention for treating nitrate waste water and methane waste gas, the voltage state of the reaction device is monitored in real time by the voltage sensor 15 arranged on the wire 18 . When the voltage deviates from the predetermined value, the alarm 17 connected in series with the voltage sensor 15 will issue an alarm, indicating that the reactor is operating abnormally.

The above-mentioned embodiment is only a preferred solution of the present invention, but it is not intended to limit the present invention. Various changes and modifications can also be made by those of ordinary skill in the relevant technical field without departing from the spirit and scope of the present invention. Therefore, all technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims (10)

1. A denitrification anaerobic methane oxidation film bioelectrochemical reaction device is characterized by comprising a closed cylinder, a cathode and an anode which are positioned in the inner cavity of the cylinder, wherein the cathode and the anode are respectively communicated with the cathode and the anode of an external power supply through leads (18);

the anode comprises a titanium mesh (13), granular activated carbon (11) and an MBR (membrane bioreactor) membrane module (12), wherein the titanium mesh (13) wraps the granular activated carbon (11) on the surface of the MBR membrane module (12); the surfaces of the granular activated carbon (11) and the MBR membrane component (12) are used for enriching denitrifying anaerobic methane oxidation microorganisms, the titanium mesh (13) is externally connected with titanium wires (14) and communicated with the lead (18), and the water outlet end of the MBR membrane component (12) is communicated with the outside through a water outlet pipe provided with a water outlet pump (1); the cathode is a carbon felt (19) with the surface used for enriching autotrophic denitrifying microorganisms;

water distribution pipes (7) with uniform holes are arranged in the inner cavity of the cylinder body below the anode and the cathode, and a gas distributor (8) is arranged below the water distribution pipes (7); the gas inlet end of the gas distributor (8) is communicated with the outside and is used for blowing gas to the anode to ensure that the granular activated carbon (11) achieves a fluidized state; the side wall of the upper part of the cylinder body is provided with a gas outlet (2), and the gas outlet (2) is communicated with the gas inlet end of the gas distributor (8) through a gas pipeline provided with a circulating pump (4).

2. The device for the bioelectrochemical reaction of the anaerobic denitrification methane oxidation membrane according to claim 1, wherein the water distribution pipe (7) has an opening ratio of 10%, and a water inlet pump (5) is provided on the water distribution pipe (7) located outside the cylinder.

3. The denitrification anaerobic methane oxidation film bioelectrochemical reaction device according to claim 1, wherein the gas distributor (8) is a disk distributor, and an aeration pump (10) is arranged at the air inlet end of the gas distributor located outside the cylinder.

4. The device for the biochemical reaction of the denitrification anaerobic methane oxidation film according to the claim 1, characterized in that a sampling port (3) is arranged on the side wall of the cylinder body close to the anode.

5. The denitrification anaerobic methane oxidation film bioelectrochemical reaction device according to claim 1, wherein the mesh opening of the titanium mesh (13) is a diamond mesh opening, and the length of the short diagonal thereof is 1 mm.

6. The denitrification anaerobic methane oxidation membrane bioelectrochemical reaction device according to claim 1, wherein the material of the MBR membrane module (12) is polyvinylidene fluoride (PVDF).

7. The device for the biochemical reaction of the denitrification anaerobic methane oxidation membrane as claimed in claim 1, wherein the conducting wire (18) is connected with a voltage sensor (15) and an alarm (17) in series in turn and is connected with a resistor (16) with the size of 500-1000 Ω in parallel to monitor the voltage state of the reaction device in real time.

8. The bio-electrochemical reaction device for the denitrification anaerobic methane oxidation film according to claim 1, wherein the granular activated carbon (11) is spherical granules with an average particle diameter of 2 mm; the filling degree of the granular activated carbon (11) on the surface of the MBR membrane module (12) is 20%.

9. A method for treating nitrate wastewater and methane exhaust gas by using the reaction device according to any one of claims 1 to 8, which is characterized by comprising the following steps:

starting a water inlet pump (5), and introducing the nitrate wastewater into the inner cavity of the barrel through a water distribution pipe (7) to realize uniform distribution; simultaneously, starting an aeration pump (10), introducing the methane waste gas into the inner cavity of the cylinder through a gas distributor (8) and enabling the methane waste gas to be fully contacted with the wastewater, and dissolving the methane gas in the wastewater;

turning off the aeration pump (10) and turning on the circulating pump (4); methane gas which is not dissolved in the wastewater at the top of the inner cavity of the cylinder body is pumped to the gas inlet end of the gas distributor (8) again under the action of the circulating pump (4), so that the cyclic utilization of the methane gas is realized; the flow rate of the methane gas is adjusted by controlling the circulating pump (4), so that the granular activated carbon (11) is fluidized;

nitrate in the wastewater and methane dissolved in the wastewater are enriched on the granular activated carbon (11) and denitrifying anaerobic methane oxidizing microorganisms on the surface of the MBR membrane component (12) and synchronously converted into nitrogen and carbon dioxide, and meanwhile, generated electrons are transferred to the granular activated carbon (11), and the activity of the denitrifying anaerobic methane oxidizing microorganisms is improved by the aid of the bioelectrochemistry promotion; the generated electrons are transmitted to the titanium net (13) from the granular activated carbon (11) through the mutual collision action of the granular activated carbon (11) and the titanium net (13), and then are transmitted to the carbon felt (19) through the external titanium wire (14) through the lead (18); autotrophic denitrification microorganisms enriched on the surface of the carbon felt (19) further reduce the nitrate in the water into nitrogen by utilizing electrons;

monitoring the voltage state of the reaction device in real time through a voltage sensor (15) arranged on a lead (18); an alarm (17) in series with the voltage sensor (15) issues an alarm when the voltage deviates from a predetermined value.

10. The method for treating nitrate containing wastewater and methane offgas as claimed in claim 9, wherein the wastewater introduced into the cylinder occupies 3/4 of the volume of the cylinder cavity.

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