Apparatus and method for treating low-carbon wastewater based on bacteria-algae symbiotic membraneless microbial fuel cell

Abstract

The application belongs to the technical field of sewage repair, and particularly relates to a device and method for treating low-carbon wastewater based on a bacteria-algae symbiotic membraneless microbial fuel cell. The device has a U-shaped structure, one end of which is an anode chamber and the other end is a cathode chamber. The anode chamber and the cathode chamber are in communication, and the top end of the anode chamber is higher than the top end of the cathode chamber. A water inlet pipe is connected to the anode chamber through a plug; the anode is attached with an anaerobic microbial membrane and activated carbon particles; the top end of the cathode chamber is a sealed rectangular structure, and the cathode is attached with a microalgae biological membrane and activated carbon particles; an overflow plate is arranged on the right side of the cathode chamber, and a gap is left between the top end of the overflow plate and the top end plate of the anode chamber; and a water outlet pipe is arranged on the right side wall of the rectangular structure. The application uses a membraneless algae-bacteria system to realize continuous flow of water, can domesticate and inoculate microalgae biological groups, and can realize efficient removal of antibiotics ARGs and the like through the synergistic effect between algae and bacteria for low-carbon wastewater containing antibiotics, has a short residence time, low operation cost, no pollution, and can generate electricity by itself.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sewage remediation, and particularly relates to a device and method for simultaneously removing nitrogen and antibiotics in low-carbon wastewater based on cathode bacteria and algal symbiosis membraneless microbial fuel cell. BACKGROUND

[0002] In recent years, the consumption of antibiotics has been increasing worldwide, and they are widely used in the medical and breeding industries. Sulfonamide antibiotics (SAs) have been widely used in the treatment of microbial infections in human therapy, livestock production and aquaculture due to their broad-spectrum antibacterial characteristics. Sulfonamides are very stable at room temperature, have a long half-life, and a low adsorption coefficient, so they have high mobility in surface water and groundwater, posing a threat to the growth of bacteria, algae and aquatic plants, and affecting the structure and function of microbial communities. Sulfanilamide (SDZ) is the most typical one of sulfonamide antibiotics, which can inhibit the function of dihydrofolate synthetase in microbial cells and block the biosynthesis of folate, thereby affecting the growth of microorganisms. Due to its strong antibacterial effect, SDZ is the most widely used among sulfonamide antibiotics and is reported as a "high priority" sulfonamide drug, which is often detected in environmental samples and has also attracted attention on the risk of its resistant gene transmission.

[0003] Investigations and researches have found that after a certain amount of antibiotics is ingested by humans and animals, 85% of the antibiotics are excreted through urine or feces, and only 15% of the antibiotics can be absorbed and metabolized, most of which will flow into sewage treatment plants with excrement. According to statistics, the total amount of livestock and poultry manure produced in China each year is about 4 billion tons, and the wastewater contains a large amount of organic pollutants. At the same time, the high concentration of COD, N and P in wastewater promotes the accumulation of sulfonamide antibiotic resistance genes. As an important unit for the treatment of antibiotics and bacteria, the wastewater and sludge in sewage treatment plants may change the size and distribution of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs), and if not properly treated, it may threaten the ecological balance and safety of the receiving environment.

[0004] Current wastewater treatment technologies such as sedimentation, physical adsorption and membrane separation can only extract or separate antibiotics from the environment, and cannot destroy their internal structure from the chemical level of organic matter. Chemical processes such as ozonation, Fenton oxidation and photocatalysis are prone to form harmful by-products and high energy consumption, and are expensive in terms of chemicals and equipment. As a common biological treatment process, activated sludge is widely used, but its most serious problem is the risk of producing antibiotic-resistant bacteria. Bacterial fermentation can occur in activated sludge, and exposure to antibiotics can lead to the proliferation of resistant bacteria, forming new genetic pollutants. In general, traditional processes for removing antibiotics from water currently have problems such as high cost, long time, easy secondary pollution, harmful by-products and resistant bacteria, and cannot achieve efficient degradation. Therefore, new methods need to be explored to improve the removal efficiency of antibiotics.

[0005] Algal-bacterial symbiotic bioelectrochemical systems have been applied to the removal of nutrients in wastewater. This system uses the cooperation of algae and bacteria to decompose and remove pollutants. Algae use sunlight and CO2 to produce organic carbon, while bacteria use this organic carbon to grow and produce enzymes that decompose pollutants. These two organisms create a balanced and self-sustaining system that can effectively remove various pollutants such as COD, N, P and other organic matter from water, and has the advantages of no pollution, low energy consumption, low cost, high efficiency and the ability to produce valuable biomass.

[0006] A typical algal-bacterial symbiotic bioelectrochemical system includes an anode, a cathode, an electric wire that generates an electron flow, and a proton exchange membrane, commonly in an H-shaped structure. The anode chamber is usually domestic wastewater, textile wastewater, etc., and the cathode chamber is usually the growth medium for algae. The two chambers are separated by a proton exchange membrane, and each chamber has an electrode connected by an electric wire. The main function of the proton exchange membrane is to transport H + ions from the anode chamber to the cathode chamber. Since the proton exchange membrane acts as a separator between the anode and cathode chambers, it needs to be compatible with the media on both sides, and also needs to have high ion and mechanical conductivity to support stable ion transport through the membrane. The stability is determined by the material of the proton exchange membrane, which usually uses hydrogel or polymer, which greatly increases the cost of the device, and also causes problems such as membrane fouling and low output power due to small membrane area.

[0007] Therefore, a new process is needed that can both take advantage of the high efficiency of algal-bacterial symbiosis for wastewater treatment and overcome the shortcomings of existing processes caused by proton exchange membranes to achieve effective removal of organic matter in wastewater. However, there is currently little research on the application of algal-bacterial symbiosis technology to remove antibiotics from wastewater, especially to reduce ARGs. SUMMARY

[0008] The technical problem to be solved by the present application is to provide a device and method for treating low-carbon wastewater based on a bacteria-algae symbiotic membraneless microbial fuel cell, so as to remove ARGs and common organic matter such as COD and N in low-carbon wastewater. The biological method has the advantages of high removal efficiency of ARGs and common organic matter in wastewater, short treatment cycle, low cost, no pollution, and potential for large-scale promotion. The technical scheme adopted is as follows:

[0009] The device for treating low-carbon wastewater based on bacteria-algae symbiotic membraneless microbial fuel cell has a U-shaped structure, one end of which is an anode chamber and the other end of which is a cathode chamber. The anode chamber and the cathode chamber are in communication, and the top end of the anode chamber is higher than the top end of the cathode chamber.

[0010] The top end of the anode chamber is sealed with a plug, and a hole for installing a water inlet pipe is provided on the plug. The water inlet pipe penetrates into the anode chamber. An anode electrode is installed in the center of the anode chamber, and anaerobic microbial membrane and activated carbon particles are attached to the anode.

[0011] The top end of the cathode chamber is a sealed rectangular structure, and a cathode electrode is arranged in the center. Microalgae biofilm and activated carbon particles are attached to the cathode. An overflow plate is arranged on the right side of the rectangular structure of the cathode chamber, and a gap is left between the top end of the overflow plate and the top end plate of the anode chamber. A water outlet pipe is arranged on the right side wall of the rectangular structure.

[0012] The anode electrode and the cathode electrode are connected through an external circuit and connected to a data acquisition device and an electric device. The electric device can be a resistor, a small electric appliance, or a power storage device.

[0013] Preferably, the anode and the cathode are carbon brush electrodes. A water inlet valve is arranged at the inlet of the water inlet pipe, and a water outlet valve is arranged at the outlet of the water outlet pipe.

[0014] Preferably, the anaerobic microbial membrane is generated by anaerobic electroactive bacteria, such as Geobacter and Shewanella.

[0015] Preferably, an aeration device is arranged in the cathode chamber. At least one aeration device is arranged, and generally two aeration devices are arranged.

[0016] Preferably, ceramic fragments and rubble are placed at the bottom end of the U-shaped structure of the device to separate the anode chamber and the cathode chamber, so as to realize continuous flow of water without interruption.

[0017] A biological electrochemical wastewater treatment method based on membraneless algae-bacteria symbiosis, which adopts the device for treating low-carbon wastewater based on bacteria-algae symbiotic membraneless microbial fuel cell, comprises the following steps:

[0018] 1) Before using the device, a certain amount of anaerobic sludge is inoculated on the anode electrode in the anode chamber to form an anaerobic microbial membrane; and mixed algae in the logarithmic growth phase are inoculated on the surface of the cathode electrode in the cathode chamber to form a microalgae biofilm on the surface of the cathode electrode.

[0019] 2) through the water inlet pipe to the anode chamber injection of a certain amount of low carbon wastewater to be treated, and the anode chamber sealed treatment, anode electrode and cathode electrode connection outside the use of electrical equipment and data acquisition, after starting the reactor, using data acquisition to monitor the voltage between the anode electrode and cathode electrode, when the voltage is stable at 0.05-0.07v, replace the low carbon wastewater, to be produced electricity microorganism to adapt to the surrounding environment, the device runs well, the voltage rises to stable (about at 0.06-0.08v), the system is started successfully, the biological membrane domestication is completed, then empty the low carbon wastewater;

[0020] 3) the low carbon wastewater to be treated through the water inlet pipe into the anode chamber, under the action of gravity, low carbon wastewater is fully mixed and fully contacted with anaerobic microbial membrane, anaerobic electroactive bacteria enriched in anaerobic microbial membrane oxidize organic matter in low carbon wastewater, and metabolic oxidation produces electrons and protons, electrons flow back to the cathode through the external circuit to generate current, and protons flow to the cathode with water to generate water in the cathode chamber;

[0021] 4) the low carbon wastewater treated through the anode chamber flows into the cathode chamber, the microalgae biofilm attached to the surface of the cathode electrode utilizes CO2 and N and P in the low carbon wastewater to carry out photosynthesis to produce oxygen, synthesizes its own life at the same time, and forms an algae-bacteria symbiotic system with aerobic microorganisms to remove nitrogen, antibiotics and other organic matters in the low carbon wastewater.

[0022] As a further preferred, the method for inoculating the anode is:

[0023] Before inoculating the anaerobic sludge, the nutrient solution is added to the anaerobic sludge at regular time, and the anaerobic sludge is stirred regularly to domesticate and keep the activity of the anaerobic sludge;

[0024] The above sludge is added to the anode chamber, the low carbon wastewater is simulated and prepared, the prepared low carbon wastewater culture medium is added to the anode every 24 hours, SDZ is added during the domestication process, and the device is continuously operated for 30 days.

[0025] Preferably, the concentration of the added SDZ is 200 μg / L.

[0026] As a further preferred, the method for inoculating the cathode is:

[0027] The low carbon wastewater sample is directly enriched and cultured, inoculated into the BG-11 culture medium (i.e. inorganic salt basic culture medium, mainly composed of the following elements: NaNO3, K2HPO4, MgSO4, CaCl2, FeSO4, Na2CO3 and EDTA, etc.), and cultured in a constant temperature incubator at 25℃ under illumination of 6000 lux until the logarithmic phase, as an algae seed, stored in the dark for standby.

[0028] Preferably, the hydraulic retention time in the step 4) is 1 day

[0029] Compared with the prior art, the present application has the beneficial effects that:

[0030] 1) The present application is different from the common algal-bacterial symbiotic bio-electrochemical system, and realizes continuous flow water by adopting a membrane-free algal-bacterial system, has the characteristics of short treatment period, high degradation efficiency, simple treatment process, low operation cost and no pollution, especially the treatment period only needs 1 day to realize the degradation rate of more than 99%, and can generate electricity by itself without additional power supply, and can store electric energy;

[0031] 2) The present application can realize efficient removal of organic matter in low-carbon wastewater through the synergistic effect between algae and bacteria by domesticating and inoculating microalgae biological groups for the influent containing antibiotic low-carbon wastewater, especially showing strong denitrification ability and antibiotic degradation ability;

[0032] 3) The present application combines the efficient removal ability of traditional aerobic and anaerobic biological treatment technology and the synergistic mechanism of algal-bacterial symbiotic purification of low-carbon wastewater, further optimizes the efficiency of microbial fuel cell, and realizes efficient synchronous removal of organic matter in water. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The device structure schematic diagram of the embodiment 1 of the present application;

[0034] Figure 2 The influence of different SDZ concentrations of the test example and the control group on (a) SDZ, (b) COD and (c) nitrogen degradation, wherein +: with membrane (the present application), -: without membrane (the control group);

[0035] Figure 3 (a) Relative abundance of resistance genes in effluent of membrane-free algal-bacteria and (b) relative abundance of resistance genes in effluent of membrane algal-bacteria.

[0036] Figure 4 The influence of different ammonia nitrogen concentrations of the test example and the control group on (a) SDZ, (b) COD and (c) nitrogen degradation, wherein +: with membrane (the present application), -: without membrane (the control group).

[0037] In the figure, 1 is an inlet valve, 2 is an inlet pipe, 3 is a cork, 4 is an anode chamber, 5 is an anaerobic microbial membrane, 6 is an anode electrode (carbon brush), 7 is an activated carbon particle, 8 is a ceramic fragment, 9 is a resistor, 10 is a titanium wire, 11 is a microalgae biological membrane, 12 is an aeration device, 13 is a cathode chamber, 14 is an overflow plate, 15 is an outlet valve, 16 is an outlet pipe, 17 is a cathode electrode (carbon brush), 18 is a gravel, 19 is a data collector, and 20 is a wire. DETAILED DESCRIPTION

[0038] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the invention. To better illustrate this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. Terms such as "upper," "lower," "top," "bottom," "side," "outer," "left," and "right" indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, not to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the invention. For those skilled in the art, some well-known structures and their descriptions in the drawings may be omitted.

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be further described and explained below in conjunction with the accompanying drawings and specific embodiments.

[0040] like Figure 1 The image shows the device for treating low-carbon wastewater based on a membrane-free microbial fuel cell with algae-bacterial symbiosis provided by the present invention. The device adopts a U-shaped membrane-free microbial fuel cell configuration, and the specific structure of each component is as follows:

[0041] The anode chamber 4 is a sealed structure with an internal cavity, sealed with a cork stopper 3. An inlet is located at the top of the anode chamber 4, connected to an inlet pipe 2 that communicates with an external water supply device. An inlet valve 1 is also installed on the inlet pipe 2 to control the flow rate of low-carbon wastewater entering the anode chamber 4. An anode electrode 6 is fixed within the internal cavity of the anode chamber 4. The surface of the anode electrode 6 is used to attach an anaerobic microbial film 5, which is enriched with sufficient anaerobic electroactive bacteria, a mixture of bacteria such as Geobacterium and Shewanella.

[0042] To provide better attachment sites for microorganisms, the anode electrode 5 is a carbon brush formed by hand-winding carbon fiber and corrosion-resistant titanium wire. It is used after acid treatment and heat treatment, which can increase the output power. There is no proton exchange membrane between the anode chamber 4 and the cathode chamber 13. Ceramic fragments 8 and gravel 18 are used to separate them to achieve uninterrupted continuous water flow.

[0043] The cathode chamber 13 is a transparent rectangular hollow cavity structure made of plexiglass, ensuring light transmission, corrosion resistance, and insulation. The cathode chamber 13 contains an aeration device 12 to provide oxygen for aeration within the cathode chamber 15. The hollow cavity also contains a cathode electrode 17 composed of carbon brushes, the surface of which is used to attach a microalgae biofilm 11. Both the cathode chamber 13 and the anode chamber 4 are filled with activated carbon particles 7.

[0044] Anode electrode 6 and cathode electrode 17 are connected with titanium wire 10 to connect external circuit with resistance 9, in order to measure voltage between anode electrode 6 and cathode electrode 17, to represent whether the production capacity of the treatment device of the application is stable, data collector 19 can be connected between anode electrode 6 and cathode electrode 17 with wire 20, to represent whether the reaction production capacity is stable by collecting potential change between anode and cathode, to monitor voltage between anode electrode 6 and cathode electrode 17 in real time.

[0045] Overflow plate 14 is arranged on the right side of cathode chamber 13, and low-carbon wastewater treated by the cathode chamber is discharged through water outlet pipe 16 at the bottom, and water outlet valve 15 is arranged on water outlet pipe 16.

[0046] The method for treating nitrogen, antibiotics and other organic matters in low-carbon wastewater by using the device is as follows:

[0047] Firstly, before the sewage treatment device is used, i.e. in the reactor starting stage, a certain amount of anaerobic sludge with stable efficiency after domestication by an organic wastewater anaerobic treatment reactor is inoculated on anode electrode 6 in anode chamber 4, so as to form anaerobic microbial membrane 5. Mixed algae in logarithmic growth phase are inoculated on the surface of cathode electrode 17 in cathode chamber 13, so as to form microalgae biofilm 11 on the surface of cathode electrode 13. A certain amount of low-carbon wastewater to be treated is injected into anode chamber 4 through water inlet pipe 2, and anode chamber 4 is sealed for treatment. After anode electrode 6 and cathode electrode 17 are connected with external resistance 9, the reactor is started, and data collector 19 is used to monitor voltage between anode electrode 6 and cathode electrode 17, when the voltage is stable at a low level and does not change, the low-carbon wastewater is replaced, and after the voltage output and the pollutant removal rate are continuously stable, the biofilm domestication is completed. Then, the low-carbon wastewater in the sewage treatment device is emptied.

[0048] a. Anode inoculation: the activated sludge of a sewage treatment plant in Qingdao is used for anode inoculation, before inoculating the reactor, nutrient solution is added to the sludge at regular time, and the sludge is stirred regularly, so that the sludge is domesticated and kept active. 500 mL of activated sludge is added to the anode chamber, high-concentration simulated low-carbon wastewater is prepared, the culture medium is diluted according to the operation parameters to be used as experimental water, SDZ (200 μg / L) is added during the domestication process, and the system is continuously operated for 30 days, whether the system is successfully started is judged by regularly detecting the pollutant concentration of the effluent and recording the change of the load resistance voltage.

[0049] b.Cathode inoculation: mixed algae was inoculated in BG-11 medium, and the mixed algae was directly enriched and cultured without separation and purification from a sewage treatment plant in Qingdao, belonging to freshwater green algae. The water sample was inoculated in BG-11 medium and cultured in a constant temperature incubator at 25℃ with illumination of 6000 lux. The logarithmic phase was used as the algae seed and stored in the dark for standby. 1000 mL of the required diluted sewage medium was added to the anode every 24 hours, and the reactor entered the start-up mode. The initial battery voltage was low, and the power generation microorganisms adapted to the surrounding environment. After the device ran well, the voltage rose to a stable level, indicating that the system started successfully.

[0050] The low-carbon wastewater to be treated is introduced into the anode chamber 4 through the inlet pipe 2, and the low-carbon wastewater is fully mixed and contacted with the anaerobic microbial membrane 5 under the action of gravity. The anaerobic electroactive bacteria enriched in the anaerobic microbial membrane 5 have the function of oxidizing organic matter. The substrate is metabolically oxidized to produce electrons and protons. The electrons flow back to the cathode through the external circuit to generate current, and the protons flow to the cathode with water to form water in the cathode chamber 13. The process of anaerobic digestion includes hydrolysis and fermentation, production of small molecule acids, etc.

[0051] The low-carbon wastewater treated by the anode chamber 4 flows into the cathode chamber 13, and the microalgae biofilm 11 attached to the surface of the cathode electrode 17 uses CO2 and N and P in the low-carbon wastewater for photosynthesis to produce oxygen, synthesizes its own life at the same time, and forms an algal-bacterial symbiotic system with aerobic microorganisms to remove N and P in the low-carbon wastewater. At the same time, the microalgae biofilm 11 mainly degrades SDZ in the water phase through three ways of biological adsorption, biological accumulation and biodegradation, among which biodegradation is the most effective way.

[0052] In the process of biodegradation of SDZ, the S-N bond is first hydrolyzed, and the SDZ molecule is cracked into P1 (C6H7O3NS, m / z: 174.53) and P4 (C4H5N3 m / z: 96.05), P1 is reduced to P2 (C6H7O2NS, m / z: 158.15), and the N atom in the P2 molecule may be further consumed by microorganisms to generate P3 (C6H6O2S m / z: 142.03). Similarly, P4 may also be formed by amino oxidation to form P5 (C4H3O2N3 m / z: 125.99), and P5 is converted into P3 by hydroxylation.

[0053] According to the proposed degradation mechanism, hydrolysis is the initial step of SDZ degradation, and the research finds that when the isolated pure culture such as Arthrobacter, Microbacterium, Paracoccus, Methylobacterium sp. and Kribbella biodegrades SDZ, SDZ can be hydrolyzed into P4, and converted into P6 (C4H5ON3 m / z: 112.01) through a hydroxylation reaction, further converted into P7 (C4H5O2N3 m / z: 112.01), and the amino group of P7 is oxidized into P8 (C4H5O3N3 m / z: 144.00). In addition, SDZ is easy to release SO2 to generate P10 (C 10 H 10 N4 m / z: 187.10), further mineralized to generate CO2 and H2O, and the SDZ pyrimidine ring can be generated by the rupture of C-N bond to generate P9 (C7H 10 O2N4S m / z: 214.92). In the biodegradation process of SDZ in the device, the metabolic pathway mainly includes SDZ hydrolysis, hydroxylation, sulfur reduction, denitrification, C-N bond rupture and amino oxidation reactions.

[0054] In the present study, electron transfer occurs in the life activities of different functional bacterial flora, and through microbial action, SDZ can be more comprehensively and completely removed in the reactor.

[0055] Test Example 1

[0056] The device of the present application is tested, and the degradation efficiency of the pollutant by the membrane-free algae bacterial symbiotic bioelectrochemical system under different initial concentrations of SDZ is tested. Light:dark = 12:12h, room temperature, 24h aeration in the cathode chamber, hydraulic retention time 1d.

[0057] After the system is successfully started, the artificial simulated low-carbon wastewater is injected through the water inlet pipe, and the wastewater is divided into five different initial concentrations of SDZ, which are 1, 10, 20, 30 and 40 mg / L, and each concentration experiment period is 10d, and the early stage is the acclimation stage, and water samples are taken from the cathode effluent of the two systems every day in the last three days of each period, and the N, COD and SDZ concentrations are detected, so as to know the degradation rate.

[0058] After the water sample is filtered through a 0.45μm filter membrane, the concentrations of COD, ammonia nitrogen (NH4 + -N), nitrate nitrogen (NO3 - -N) and nitrite nitrogen (NO2 - -N) are measured, and the measurement method refers to the national standard method. The test data are processed and plotted by Origin 9.0, and the specific results are shown in Figure 2as shown.

[0059] The content of SDZ was determined by a Japanese Shimadzu high performance liquid chromatograph (LC-2040C 3D). The water sample was filtered by a 0.22 mm organic microporous filter (nylon 66, 13 mm, 0.22 mm) and then subjected to LC analysis. The chromatographic column was a C18 column (4.6 mm x 250 mm, 5 μm), the mobile phase was acetonitrile: phosphoric acid water (1% phosphoric acid) = 20:80, the flow rate was 0.8 mL / min, the column temperature was 35°C, the injection amount was 20 μL, and the ultraviolet detection wavelength was 265 nm.

[0060] Control group 1

[0061] A common membrane algae bacteria system was set up for a control experiment to verify the degradation effect of the biological electrochemical sewage treatment device based on the non-membrane algae bacteria symbiosis of the present application on pollutants in the prior art. The existing membrane algae bacteria system needs to be powered by an external power source to start, cannot generate electricity by itself, adopts an H-shaped structure, and the anode chamber and the cathode chamber are separated by a proton exchange membrane. The anode adopts common carbon paper as the electrode, and the cathode adopts common carbon paper containing platinum, which can be purchased from a manufacturer. Other experimental conditions are the same.

[0062] The device of the present application does not need an external power source and can itself realize electricity generation performance. The device of the present application has good removal effects on SDZ and other pollutants under different sulfadiazine concentrations (1, 10, 20, 30, 40 mg / L), and the initial concentration of SDZ has little effect on the non-membrane algae bacteria symbiotic system. The degradation rates of SDZ, COD and ammonia nitrogen are all higher than those of the system of the control group, especially when the concentration of SDZ is 20 mg / L, the removal rate difference is the largest. The device of the present application shows good removal effect during treatment, especially the removal rate of SDZ, which can reach 99.98%. In general, when the concentration of SDZ is 20 mg / L, the device of the present application has the best running effect, and the comparison results are shown in Figure 2 The platinum-containing biological fuel cell of the control group is not suitable for large-scale promotion and use, and the H-shaped structure is not thorough enough in degradation.

[0063] Test example 2

[0064] In the test example 1, the degradation performance of the system on pollutants under different initial concentrations of SDZ was studied, and the resistance genes of the effluent sample under different concentrations of the system were detected. The degradation performance of the device of the present application was observed by analyzing the relative abundance of sul I, sul II and sul III three resistance genes, and the details are shown in Figure 3

[0065] ​Microbial samples of the present application and the control group were collected respectively, and genomic DNA was extracted using the Power Soil DNA Isolation Kit (MoBio, Carlsbad, CA, USA) according to the manufacturer's instructions. The CFX Connect Real-Time PCR system (Bio-Rad, Shanghai, China) and SYBR Green qPCR kit (Bio-Rad, Shanghai, China) were used to detect three sulfa resistance genes (sul I, sul II, and sul III). Considering the different microbial abundances, matrix effects, and DNA extraction efficiencies between samples, the 16S rRNA abundance of each sample was also quantified to standardize the detected ARG (i.e., ARG copy number / 16S rRNA copy number). The determination coefficient (R2) was greater than 0.990. The primers required for detection are shown in Table 1.

[0066] Table 1 PCR primers for ARGs and 16rRNA

[0067]

[0068] As Figure 3 shown, compared with the present application, the SDZ produced more sul resistance genes through the control group system, among which sul I and sul II genes were the most common ARGs in all samples. As the concentration of SDZ increased from 1 mg / L to 40 mg / L, the relative abundance of sul I gene increased from 2.6 x 10 -4 to 8.5 x 10 -3 , and the relative abundance of sul II gene increased from 5.3 x 10 -4 to 2.7 x 10 -2 . The relative abundance of sul III was significantly less than that of sul I and sul II. The experimental results showed that the membraneless algae-bacteria symbiotic technology of the present application could significantly improve the ability of the reactor to inhibit the production of ARGs. When SDZ < 20 mg / L, the relative abundance of sul gene was less affected by the concentration, and the average relative abundance of sul I, sul II, and sul III was 5.76 x 10 -6 , 5.56 x 10 -6 , and 5.43 x 10 -7 , respectively, which was 3.11 x 10 -3 , 2.71 x 10 -3 , and 2.10 x 10 -4 lower than the symbiotic technology of the control group. Although the relative abundance of sul gene increased as the concentration of SDZ increased to 30 mg / L, the removal performance of the membraneless algae-bacteria symbiotic technology of the present application was still better than that of the control group.

[0069] Test Example 3

[0070] The device of the application is used for testing, and the degradation efficiency of pollutants by the bio-electrochemical system of the algae fungus symbiosis without membrane under different initial ammonia nitrogen concentrations. Light:dark = 12:12h, room temperature, 24h aeration in the cathode chamber, hydraulic retention time 1d, which is better than the prior art (3-7 days).

[0071] After the system is successfully started, the artificial simulated low-carbon wastewater is injected through the water inlet pipe, and ammonium chloride is selected as the additional nitrogen source. The initial ammonia nitrogen concentration is divided into five different concentrations, which are 1, 20, 40, 60 and 100mg / L. In order to ensure the stable operation of the device and obtain accurate experimental data, the experimental period of each concentration is 10d, and the early stage is the acclimation stage. Water samples are taken from the cathode effluent of the two systems every day in the last three days of each period, and the N, COD and SDZ concentrations are detected, so as to know the degradation rate.

[0072] After the water sample is filtered through a 0.45μm filter membrane, the COD, ammonia nitrogen (NH4 + -N), nitrate nitrogen (NO3 - -N) and nitrite nitrogen (NO2 - -N) concentrations are measured. The measurement method refers to the national standard method. The test data are processed and plotted by Origin9.0, and the specific results are shown in Figure 4 .

[0073] The SDZ content is measured by a Japanese Shimadzu high-performance liquid chromatograph (LC-2040C 3D). The water sample is filtered through a 0.22mm organic microporous filter (nylon 66, 13mm, 0.22mm) and then subjected to LC analysis. The chromatographic column is a C18 column (4.6mm×250mm, 5μm), the mobile phase is acetonitrile:phosphoric acid water (1% phosphoric acid) = 20:80, the flow rate is 0.8mL / min, the column temperature is 35℃, the injection amount is 20μL, and the ultraviolet detection wavelength is 265nm.

[0074] Control group 2

[0075] A common algae fungus system is set up for a control experiment to verify the degradation effect of pollutants by the bio-electrochemical wastewater treatment device based on the algae fungus symbiosis without membrane of the application and the prior art. The existing algae fungus system with membrane needs to be powered by an external power supply to start, and itself cannot generate electricity. The H-shaped structure is adopted, the anode chamber and the cathode chamber are separated by a proton exchange membrane, the anode adopts common carbon paper as the electrode, and the cathode adopts common carbon paper containing platinum, which can be purchased from the manufacturer. The hydraulic retention time is 5d, and other experimental conditions are the same.

[0076] As Figure 4As shown, (a) shows the removal effect of SDZ by two algae-bacteria symbiotic devices under different ammonia nitrogen concentrations, from the figure, it can be seen that the removal rate of SDZ by the membrane-free system is higher than that by the membrane system under different ammonia nitrogen concentrations, and the difference between them is the largest when the ammonia nitrogen concentration is 20 mg / L, and the membrane-free system performs best, with a removal rate of SDZ as high as 99%. (b) shows the removal effect of COD by two algae-bacteria symbiotic devices under different ammonia nitrogen concentrations, and similarly, the degradation rate of COD by the membrane-free system is still higher than that by the membrane system. (c) shows the removal effect of nitrogen by two algae-bacteria symbiotic devices under different ammonia nitrogen concentrations, which are ammonia nitrogen (c1), nitrate nitrogen (c2) and nitrite nitrogen (c3), respectively, from the figure, it can be seen that the degradation effect of ammonia nitrogen (c1) by the membrane-free system is far better than that by the membrane system, with a removal rate as high as 99%, and only a small amount of nitrate nitrogen (3-10%) and nitrite nitrogen (0.10-0.14%) is generated, in contrast, the removal capacity of ammonia nitrogen by the membrane system is weak, with a maximum of 81%, and a large amount of nitrate nitrogen (8-19%) and nitrite nitrogen (0.19-0.26%) is detected in the cathode effluent sample, indicating that the degradation capacity of nitrogen by the membrane system is general, and is not as good as that by the device of the present application.

[0077] Of course, the above description is not a limitation of the present application, and the present application is not limited to the above examples, and the changes, modifications, additions or substitutions made by the person skilled in the art within the essential scope of the present application should also belong to the protection scope of the present application.

Claims

1. A method for treating low-carbon wastewater based on a biomembrane-free microbial fuel cell with algae-bacterial symbiosis, comprising an apparatus for treating low-carbon wastewater using a biomembrane-free microbial fuel cell with algae-bacterial symbiosis, characterized in that, The device has a U-shaped structure, with an anode chamber at one end and a cathode chamber at the other end. The anode chamber and the cathode chamber are connected, and the top of the anode chamber is higher than the top of the cathode chamber. The top of the anode chamber is sealed with a plug, and the plug has a hole for installing a water inlet pipe, which enters the anode chamber; an anode electrode is installed in the center of the anode chamber, and the anode is attached with an anaerobic microbial film and activated carbon particles. The top of the cathode chamber is a sealed rectangular structure with a cathode electrode in the center. Microalgae biofilm and activated carbon particles are attached to the cathode. An overflow plate is installed on the right side of the rectangular structure of the cathode chamber, and a gap is left between the top of the overflow plate and the top plate of the anode chamber. A water outlet pipe is installed on the right side wall of the rectangular structure. The anode electrode and cathode electrode are connected to a data acquisition unit and electrical equipment via an external circuit; The device's U-shaped structure has ceramic fragments and gravel placed at the bottom to separate the anode chamber from the cathode chamber, enabling uninterrupted continuous water flow. The process includes the following steps: 1) Before using the device, a certain amount of anaerobic sludge is inoculated onto the anode electrode in the anode chamber to form an anaerobic microbial film; mixed algae in the logarithmic growth phase are inoculated onto the surface of the cathode electrode in the cathode chamber to form a microalgal biofilm on the cathode electrode surface. 2) Inject a certain amount of low-carbon wastewater to be treated into the anode chamber through the inlet pipe, and seal the anode chamber. Connect the anode electrode and cathode electrode to the external electrical equipment and data acquisition device, then start the reactor. Use the data acquisition device to monitor the voltage between the anode electrode and the cathode electrode. When the voltage stabilizes at 0.05~0.07V, replace the low-carbon wastewater. After the electrogenic microorganisms adapt to the surrounding environment and the voltage rises to a stable level, it indicates that the system has started successfully and the biofilm acclimatization is complete. Then, drain the low-carbon wastewater. 3) The low-carbon wastewater to be treated is introduced into the anode chamber through the inlet pipe. Under the action of gravity, the low-carbon wastewater is fully mixed and comes into full contact with the anaerobic microbial membrane. The anaerobic electroactive bacteria enriched in the anaerobic microbial membrane oxidize the organic matter in the low-carbon wastewater and produce electrons and protons through metabolic oxidation. Electrons flow from the anode back to the cathode through the external circuit to generate current. Protons reach the cathode with the water flow and combine with electrons in the cathode chamber to generate water. 4) The low-carbon wastewater treated in the anode chamber flows into the cathode chamber. The microalgae biofilm attached to the cathode electrode uses CO2 and N and P in the low-carbon wastewater to perform photosynthesis to produce oxygen. While synthesizing its own life forms, it forms an algae-bacteria symbiotic system with aerobic microorganisms to remove organic matter from the low-carbon wastewater.

2. The method for treating low-carbon wastewater based on a membrane-free microbial fuel cell with algae-bacterial symbiosis according to claim 1, characterized in that, The anode and cathode are carbon brush electrodes, and an inlet valve is installed at the inlet of the water inlet pipe and an outlet valve is installed at the outlet of the water outlet pipe.

3. The method for treating low-carbon wastewater based on a membrane-free microbial fuel cell with algae-bacterial symbiosis according to claim 1, characterized in that, The anaerobic microbial membrane is generated by anaerobic electroactive bacteria.

4. The method for treating low-carbon wastewater based on a membrane-free microbial fuel cell with algal symbiosis according to claim 1, characterized in that, An aeration device is installed in the cathode chamber.

5. The method for treating low-carbon wastewater based on a membrane-free microbial fuel cell with algal symbiosis according to claim 1, characterized in that, The method of anode inoculation is as follows: Before inoculating anaerobic sludge, nutrient solution is added to it regularly and stirred periodically to acclimate the sludge and maintain its activity. The sludge was added to the anode chamber to simulate the preparation of low-carbon wastewater. The prepared low-carbon wastewater culture medium was added to the anode every 24 hours. SDZ was added during the acclimation process and the process was carried out continuously for 30 days.

6. The method for treating low-carbon wastewater based on a membrane-free microbial fuel cell with algal symbiosis according to claim 5, characterized in that, The concentration of SDZ added was 200 µg / L.

7. The method for treating low-carbon wastewater based on a membrane-free microbial fuel cell with algal symbiosis according to claim 1, characterized in that, The method of cathode seeding is as follows: Low-carbon wastewater samples were directly enriched and cultured, inoculated into BG-11 medium, and cultured in a constant temperature incubator at 25℃ under 6000 lux light conditions until the logarithmic growth phase. The resulting algal strains were then stored in the dark for later use.

8. The method for treating low-carbon wastewater based on a membrane-free microbial fuel cell with algal symbiosis as described in claim 1, characterized in that, The hydraulic residence time in step 4) is 1 day.

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