Fluidization collision type bioelectric reaction device suitable for high-carbon sewage treatment

Abstract

The invention discloses a fluidized collision type bioelectric reaction device suitable for high-carbon sewage treatment. The device comprises a reactor body, a capacitive electroactive biofilm carrier, an anode plate and a cathode plate. The reactor body is a cylinder, the bottom of the reactor body is provided with a water impeller, and the areas are separated by grids; the capacitive electroactive biofilm carrier is a sphere formed by stacking round sheets and is made of polyethylene plated with an ITO (Indium Tin Oxide) film, and stainless steel spikes are arranged on the surface of the capacitive electroactive biofilm carrier; the cathode plate is made of graphite and is cylindrical; the anode plate is made of stainless steel compounded by lauryl sodium sulfate and graphene-multi-walled carbon nanotubes and is cylindrical, the plate wall is hollow, and the anode and the cathode are connected through a circuit. Electron transfer is completed through flowing and collision of the capacitive electroactive biofilm carrier, the mass transfer efficiency and activity of the electroactive biofilm are enhanced, the high-carbon wastewater treatment capacity is improved, and meanwhile the device has the advantages of being high in impact load resistance and low in site area requirement.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, in particular to a fluidized collision type bioelectric reaction device suitable for high-carbon sewage treatment. Background Art

[0002] High-carbon wastewater is a difficult problem in wastewater treatment. In the process of treatment, the effluent quality often fails to meet the standard due to insufficient treatment efficiency. Electroactive biofilm is more efficient than other treatment methods in treating organic matter due to its unique electron transfer mechanism, and is a new type of wastewater treatment with potential.

[0003] However, at present, electroactive biofilm is mainly suitable for sewage treatment with COD concentration below 500 mg / L. There are the following problems in treating high-carbon sewage, which seriously affect its application and promotion:

[0004] (1) Decreased mass transfer efficiency. Since the surface of the electroactive biofilm is flat, the contact efficiency between microorganisms and organic matter is low, and the mass transfer efficiency is poor; high-carbon wastewater amplifies this defect. For high-carbon wastewater with a COD concentration of 1000 mg / L, the electroactive biofilm needs two to three cycles to meet the national Class B standard.

[0005] (2) Reduction in microbial activity. When electroactive microorganisms are kept in a constant current state for a long time, their activity will drop significantly. Fluorescence staining characteristic analysis of electroactive biofilms operating under high-carbon wastewater showed that the total amount of organisms and the proportion of living cells decreased significantly over time.

[0006] (3) Influence of influent COD concentration fluctuations. When the influent COD load changes by more than 20% in a short period of time and maintains the changed load, the electroactive biofilm cannot adapt to environmental changes immediately and requires a recovery period of about 10 days for the treatment efficiency to reach the initial level, resulting in an extension of the treatment cycle and deterioration of the effluent water quality.

[0007] Therefore, in response to the problems of the prior art, the present invention proposes a fluidized collision bioelectric reaction device suitable for high-carbon wastewater treatment. The invention uses capacitive electroactive biofilm carriers as the place for the growth of electroactive microorganisms, and allows the electroactive biofilm to operate in the reactor in a fluidized manner. The main advantages of the present invention include (1) improving mass transfer efficiency. Through the fluidized state, the collision efficiency between the treatment core - capacitive electroactive biofilm carriers and organic matter is improved, thereby improving mass transfer efficiency and treatment efficiency. (2) Optimizing the power supply mode and improving microbial activity. Capacitive electroactive biofilm carriers are used to first accumulate charges in the treatment process, and then release the charges in the form of collisions to form a periodic current cycle. (3) Enhanced resistance to COD load fluctuations. By increasing the total amount and activity of microorganisms, combined with the mixing effect of sewage circulation in the reactor, the direct impact of the load is diluted, and the reactor's ability to resist load fluctuations is improved. Summary of the invention

[0008] In view of the problems of the prior art, the present invention proposes the use of a fluidized collision bioelectric reaction device suitable for high-carbon wastewater treatment. The invention uses a capacitive electroactive biofilm carrier as the growth site of electroactive microorganisms, puts the reactor in a fluidized state, and uses flow and collision to complete electron transfer, thereby improving the mass transfer efficiency of the biofilm and enhancing the activity of electroactive microorganisms. The present invention is suitable for high-carbon wastewater with a COD concentration of 1000 to 2000 mg / L, effectively improving the treatment capacity of electroactive microorganisms for high-carbon wastewater, and also has the advantages of strong resistance to shock loads and low site area requirements.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0010] A fluidized collision type bioelectric reaction device suitable for high-carbon sewage treatment comprises a reactor body, a capacitive electroactive biofilm carrier, an anode plate, and a cathode plate.

[0011] The reactor body is a cylinder; a flow maker is installed at the bottom of the reactor; from bottom to top, there are the area where the flow maker is located, the water inlet area, the reaction center part, and the water outlet area, which are separated by a grid.

[0012] The material of the capacitive electroactive biofilm carrier is polyethylene with an ITO film coated on the surface; the overall shape of the capacitive electroactive biofilm carrier is a sphere, which is composed of stacked circular sheets covered with holes; there are spikes on the surface, the material of the spikes is stainless steel, and the height is one-fifth of the radius of the sphere.

[0013] The cathode plate is made of graphite and is cylindrical in shape; it is located in the middle of the reactor and is attached to the inner wall of the reactor.

[0014] The anode plate material is stainless steel composited with sodium dodecyl sulfate and graphene-multi-walled carbon nanotubes, and is cylindrical in shape; the radius is smaller than that of the cathode plate, and is located on the inner side of the cathode plate; the wall of the anode plate is hollow, and water can pass through the pores, but capacitive electroactive biofilm carriers cannot pass through the pores; anode and cathode are connected using a line.

[0015] This invention has the following advantages:

[0016] 1. It has a higher mass transfer efficiency for high-carbon sewage. Compared with the traditional electroactive biofilm, the present invention uses a fluidized method to treat organic matter, so that the collision efficiency between the electroactive biofilm on the capacitive electroactive biofilm carrier and the organic matter in the sewage is improved, thereby improving the mass transfer efficiency and treatment efficiency.

[0017] 2. Microorganisms can remain active for a long time. The capacitive electroactive biofilm carrier is used to first accumulate the charges in the treatment process, and then release the charges through collision, forming a periodic current cycle, thereby optimizing the power supply mode. This fluctuating power supply mode can promote the metabolism of electroactive microorganisms, stimulate their electron transfer system and improve the structure of the biofilm, ultimately keeping the microorganisms active for a long time.

[0018] 3. Strong resistance to COD load fluctuations. Due to the large specific surface area of ​​the carrier and the unique power supply mode, the total amount of microorganisms in the reactor is larger and more active, and has good adaptability to changes in load. In addition, the sewage circulation in the reactor has a good mixing effect. The pollutants will be diluted when entering the reactor, and the load will be shared by each carrier, reducing the direct impact of the load; by changing the rate of sewage circulation, the dilution can be effectively accelerated and the ability to resist load fluctuations can be improved. When the load fluctuation of the influent is within 20%, it will basically not affect the system.

[0019] 4. Reduce floor space. Due to the higher volumetric load, the space required by the present invention is smaller than that of the traditional sludge treatment method. It is suitable for places with limited space or for upgrading sewage treatment plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A side cross-sectional view of a reactor according to the present invention and a three-dimensional view of the reaction core are shown.

[0021] Figure 2 A three-dimensional image (a) of the capacitive electroactive biofilm carrier of the present invention and a three-dimensional image (b) of its slice are shown.

[0022] Figure 3 The reaction flow chart of the capacitive electroactive biofilm carrier of the present invention is shown.

[0023] Figure 4 A graph of current density measurement data in Example 1 is shown.

[0024] Figure 5 The change in COD content in Example 1 is shown.

[0025] Figure 6 A comparison of the treatment effects under load fluctuation in Example 3 is shown.

[0026] Among them are:

[0027] 1. Grid; 2. Cathode; 3. Anode; 4. Flowmaker. DETAILED DESCRIPTION

[0028] The invention will be described in detail below in conjunction with the accompanying drawings and specific implementation schemes.

[0029] The mechanism of action of the reactor in the present invention is as follows:

[0030] Step 1, culturing electroactive biofilm: placing a capacitive electroactive biofilm carrier into a reactor, adding a solution containing electroactive microbial strains therein, adding vitamins, sodium acetate, and sulfate buffer under an electric environment, so that the biofilm is hung on the capacitive electroactive biofilm carrier; selecting a certain volume of the carrier to be left in the reactor so that the filling rate in the reactor meets the standard requirements.

[0031] In step 1, the main material of the capacitive electroactive biofilm carrier is a lightweight material with a density ranging from 0.89 to 0.91 g / cm 3 , can move freely with the water flow. The culture period of the biofilm on the carrier is 15 days, and the culture is successful when the biofilm thickness is 0.1 to 1 mm.

[0032] The filling rate is generally in the range of 30% to 50%. The volume of the carrier and the filling rate of the reactor can be calculated according to the following formula:

[0033]

[0034] Where Q represents the design flow rate (m 3 / d); S o Indicates the influent BOD5 concentration (mg / L); S e represents the effluent BOD5 concentration (mg / L); q represents the membrane surface load of the capacitive electroactive biofilm carrier; ε represents the specific surface area of ​​the capacitive electroactive biofilm carrier; V represents the required volume of the capacitive electroactive biofilm carrier (m 3 ); n1 represents the filling rate; V N Reaction tank volume (m 3 ).

[0035] Step 2: Perform fluidized motion: The sewage enters the reactor from the water inlet, and the flow promoter is started to circulate the sewage in the reactor. The suspended capacitive electroactive biofilm carrier flows under the impetus of the water flow, and in the process it continuously contacts and collides with organic matter. The electroactive microorganisms on the capacitive electroactive biofilm carrier decompose the organic matter.

[0036] In step 2, the stirrer makes the water flow rate greater than 0.3 m / s to ensure that the capacitive electroactive biofilm carrier is in a flowing state in the reactor. The electroactive biofilm on the capacitive electroactive biofilm carrier decomposes organic matter into H + and CO2, and the electrons generated during the reaction gather on the spikes of the carrier.

[0037] In addition to the electroactive biofilm on the capacitive electroactive biofilm carrier, the electroactive biofilm also grows on the anode of the reactor. The overall reaction of the biofilm here is the same as that of the biofilm on the capacitive electroactive biofilm carrier. The difference is that the electrons generated by the reaction are directly transmitted to the cathode by the wire. The anode material sodium dodecyl sulfate and graphene-multi-walled carbon nanotube composite stainless steel have good bioaffinity and hydrophilicity, which is conducive to the attachment of electroactive microorganisms and the transfer of electrons.

[0038] The reactions of the electroactive biofilm with organic matter on the carrier and anode surfaces are shown below.

[0039] Organic matter-e - →H + +CO2

[0040] Step 3, completing the microbial reaction: the suspended capacitive electroactive biofilm carrier collides with the anode plate during the flow process, the electrons stored on the carrier spikes are transferred to the anode and transmitted to the cathode under the action of voltage, and react at the cathode to generate water; the treated sewage is discharged from the outlet.

[0041] In step 3, the H + In the previous step, H + Passing through the hollow of the anode to reach the cathode. The reaction formula for this step is shown below.

[0042] H + +O2+e - →H2O

[0043] Example 1: Upgrading of sewage treatment plants

[0044] The influent BOD concentration of the sewage plant is about 600 mg / L. Part of the sewage is diverted into the reactor. The reactor volume is about 20m 3 , the spherical radius of the capacitive electroactive biofilm carrier is 20 mm.

[0045] (1) Electroactive organic matter was cultured on the capacitive electroactive biofilm carrier. The culture period was 15 days. The filling rate was calculated by the following formula:

[0046]

[0047] In the formula, Q represents the design flow rate, which is 1×10 3 m 3 / d;S o Indicates the influent BOD5 concentration, take 600mg / L; S e represents the effluent BOD5 concentration, estimated to be 20 mg / L; q represents the capacitive electroactive biofilm carrier membrane surface load, 0.235 g / (m 2 / d); ε represents the specific surface area of ​​the capacitive electroactive biofilm carrier, 350m 2 / m 3 ; V represents the volume of the required capacitive electroactive biofilm carrier (m 3 ); n1 represents the filling rate; V N Indicates the volume of the reaction tank, 20m 3 .

[0048] It is calculated that 7.05 m of capacitive electroactive biofilm carrier is required. 3 , the filling rate is 35.3%.

[0049] (2) Start the flow generator to circulate the sewage in the reactor and open the circuit. After the reactor has been in operation for 3 hours, measure the current density of the electrode plates. The results are as follows: Figure 4 As shown, it is proved that the electroactive microorganisms in the reactor are in a fluctuating current state and have good working efficiency in this state.

[0050] (3) The effluent after treatment is shown in Table 1, which meets the Class B standard. In addition, after the device started operating, the COD content of the sewage was measured every hour using the sampling titration method. The results are shown in Table 1. Figure 5 shown.

[0051] Table 1 Sewage treatment data table

[0052]

[0053] Example 2: Long-term sewage treatment

[0054] In long-term sewage treatment, the activity of microorganisms in traditional electroactive biofilm devices will be greatly reduced. The present invention is suitable for long-term sewage treatment and can maintain the ecological balance of microorganisms and stabilize the activity of microorganisms.

[0055] A group of traditional electroactive biofilm systems was used as a control group. The same vitamins, sodium acetate, sulfate buffer and solutions containing electroactive microbial strains were added to the present invention and the traditional electroactive biofilm system, and after 10 days of cultivation, metagenomic sequencing of the microorganisms was performed. The COD concentration of the influent sewage was controlled to be 1500 mg / L, and metagenomic sequencing was performed again after 60 days of treatment. The results of microbial sequencing are shown in Table 2. It can be observed from Table 2 that there is little difference in the microbial population at the initial stage of cultivation, but after long-term sewage treatment, the total number of microbial species, diversity and uniformity in the traditional electroactive biofilm have decreased significantly, while the present invention better maintains the microbial ecology at the initial stage of operation.

[0056] Table 2 Microbial metagenomic sequencing data

[0057]

[0058]

[0059] Example 3: Emergency handling

[0060] In the process of solving Example 1, an emergency situation of huge fluctuations in the influent water quality may be encountered, and the sewage treatment system is susceptible to changes in organic load. When the organic load increases rapidly, the biofilm may not be able to adapt to this change immediately, resulting in a decrease in removal efficiency; on the contrary, if the load decreases, the microorganisms in the biofilm may be undernourished, thereby affecting their activity and growth, which will also have a negative impact on the effluent water quality. The present invention can effectively cope with load shocks and has a stable treatment effect.

[0061] The influent organic matter load was controlled. The initial influent COD concentration was 1500 mg / L. After 5 days, the influent was changed to sewage with a COD concentration of 2000 mg / L. After another 10 days, the influent was changed back to sewage with a COD concentration of 1500 mg / L. A group of traditional electroactive biofilm systems was used as the control group. The sampling titration method was used to monitor the changes in COD concentration. The results are as follows: Figure 6 shown.

[0062] The preferred embodiments of the present invention are described in detail above; however, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all belong to the protection scope of the present invention.

Claims

1. A fluidized collision bioelectric reaction device suitable for high-carbon wastewater treatment, characterized by: It includes a reactor body, a capacitive electroactive biofilm carrier, an anode plate and a cathode plate.

2. The reactor according to claim 1, characterized in that: The reactor body is a cylinder; a flow maker is installed at the bottom of the reactor; from bottom to top, there are the area where the flow maker is located, the water inlet area, the reaction center part, and the water outlet area, which are separated by a grid.

3. The capacitive electroactive biofilm carrier according to claim 1, characterized in that: The material of the capacitive electroactive biofilm carrier is polyethylene with an ITO film coated on the surface; the overall shape of the capacitive electroactive biofilm carrier is a sphere, which is composed of stacked circular sheets covered with holes; there are spikes on the surface, the material of the spikes is stainless steel, and the height is one-fifth of the radius of the sphere.

4. The cathode plate according to claim 1, characterized in that: The cathode plate is made of graphite and is cylindrical in shape; it is located in the middle of the reactor and is attached to the inner wall of the reactor.

5. The anode plate according to claim 1, characterized in that: The anode plate material is stainless steel composited with sodium dodecyl sulfate and graphene-multi-walled carbon nanotubes, and is cylindrical in shape; the radius is smaller than that of the cathode plate, and is located on the inner side of the cathode plate; the wall of the anode plate is hollow, and water can pass through the pores, but capacitive electroactive biofilm carriers cannot pass through the pores; anode and cathode are connected using a line.

6. A method for using a fluidized collision bioelectric reaction device suitable for high-carbon wastewater treatment, characterized in that: The specific steps include: Step 1, culturing electroactive microorganisms: placing a capacitive electroactive biofilm carrier into a reactor, adding a solution containing electroactive microbial strains, adding vitamins, sodium acetate, and sulfate buffer under an electric environment, so that a biofilm is hung on the capacitive electroactive biofilm carrier, selecting a certain volume of the carrier to be left in the reactor so that the filling rate in the reactor meets the standard requirements, and the carrier volume and the reactor filling rate can be calculated according to the following formula: Where Q represents the design flow rate (m 3 / d); S o Indicates the influent BOD5 concentration (mg / L); S e represents the effluent BOD5 concentration (mg / L); q represents the membrane surface load of the capacitive electroactive biofilm carrier; ε represents the specific surface area of ​​the capacitive electroactive biofilm carrier; V represents the required volume of the capacitive electroactive biofilm carrier (m 3 ); n1 represents the filling rate; V N Reaction tank volume (m 3 ); Step 2, fluidization movement: sewage enters the reactor from the water inlet, the flow pusher is started to circulate the sewage in the reactor, and the suspended capacitive electroactive biofilm carrier flows under the impetus of the water flow; Step 3, completing the microbial reaction: starting the circuit, the capacitive electroactive biofilm carrier collides with the anode plate during the flow process, completing the reaction process; and discharging the treated sewage from the outlet.

Images