Biological method for synergistically fixing methane and carbon dioxide

Abstract

The invention provides a biological method for synergistically immobilizing methane and carbon dioxide, which comprises the following steps: mixing activated sludge with microalgae, continuously introducing gas, and forming an algal-bacterial symbiont under the condition of continuous illumination; the method comprises the following steps: putting the algal-bacterial symbiont into a reactor, pumping sewage, introducing gas, and carrying out periodic operation according to a water feeding-aeration-precipitation-drainage mode; wherein the gas comprises methane and carbon dioxide, and the sewage comprises a carbon source, a nitrogen source and a phosphorus source. According to the method, the bacteria-algae particles can be obtained through culture, and the bacteria-algae particles can provide electrons for denitrification by using the soluble methane as an electron donor, so that the purposes of synchronously removing the soluble methane and denitrifying are achieved, and the denitrification process is optimized. The bacteria-algae particles can also realize fixation of methane and carbon dioxide, the sewage treatment process is optimized, and the problems that soluble methane is difficult to remove and carbon emission is high in the existing sewage treatment process are solved.

Description

Technical Field

[0001] The present application relates to the field of sewage treatment, and in particular to a biological method for synergistically fixing methane and carbon dioxide. Background Art

[0002] In recent years, with the continuous development of sewage treatment technology, people have gradually realized that dissolved methane (D-CH4) produced in sewage treatment has become a problem that needs to be solved urgently. The concentration of dissolved methane in sewage treatment systems can reach 0.1-0.8 mg / L, and even in some high-load anaerobic reactors, its concentration can exceed 1 mg / L. If the dissolved methane produced in the sewage treatment process is directly discharged into the atmosphere without treatment, it will not only aggravate the greenhouse effect and cause global warming, but also cause energy loss.

[0003] In traditional sewage treatment technology, denitrification is the key step in denitrification. Its main mechanism is that denitrifying bacteria convert nitrate (NO3 - ) is reduced to nitrogen (N2), thereby achieving nitrogen removal. However, this process usually requires an external organic carbon source (such as methanol, acetic acid, etc.) as an electron donor to maintain the denitrification reaction. However, the added carbon source is eventually converted into carbon dioxide under the action of microorganisms, further increasing the overall carbon emissions of the sewage treatment plant, which is contrary to the green and low-carbon development concept currently advocated by the world.

[0004] As sewage treatment plants develop towards green, energy-saving and carbon-reducing directions, how to effectively remove dissolved methane and reduce carbon dioxide emissions has become an important issue that needs to be addressed urgently. Summary of the invention

[0005] The purpose of the present application is to provide a biological method for synergistically fixing methane and carbon dioxide to solve the above-mentioned problems.

[0006] To achieve the above objectives, this application adopts the following technical solutions:

[0007] A biological method for synergistically fixing methane and carbon dioxide, comprising:

[0008] Mixing activated sludge with microalgae, continuously introducing gas, and forming a bacterial-algae symbiosis under continuous light conditions;

[0009] The bacteria-algae symbiosis is put into a reactor, sewage is pumped in, the gas is introduced, and the reactor is operated in a cycle of water inlet-aeration-sedimentation-drainage;

[0010] Wherein, the gas includes methane and carbon dioxide, and the sewage includes a carbon source, a nitrogen source and a phosphorus source.

[0011] According to an embodiment of the present application, after cyclic operation in the manner of water intake-aeration-sedimentation-drainage, the bacteria-algae symbiont is transformed into bacteria-algae particles.

[0012] According to an embodiment of the present application, the gas further includes nitrogen;

[0013] Based on the total volume of the gas, the proportion of methane is 35-60%, the proportion of carbon dioxide is 15-45%, and the proportion of nitrogen is 15-30%.

[0014] According to an embodiment of the present application, the carbon source includes sodium acetate and glucose, the nitrogen source includes ammonium chloride, and the phosphorus source includes potassium dihydrogen phosphate;

[0015] And / or, the concentration of the sodium acetate is 200-800 mg / L, the concentration of the glucose is 100-400 mg / L, the concentration of the ammonium chloride is 20-90 mg / L, and the concentration of the potassium dihydrogen phosphate is 5-10 mg / L.

[0016] According to the embodiment of the present application, the concentration of the activated sludge is 3000-4000 mg / L, and the concentration of the microalgae is 10 9 ~10 11 cells / L;

[0017] And / or, the continuous illumination time is 12 to 24 hours;

[0018] And / or, the time of introducing gas is 12 to 24 hours;

[0019] And / or, the microalgae comprises Chlorella.

[0020] According to an embodiment of the present application, the light source of the continuous illumination is an LED lamp, and the illumination intensity of the continuous illumination is 10,000 to 15,000 lux.

[0021] According to an embodiment of the present application, the gas flow rate during aeration is 2.0 to 4.0 L / min;

[0022] And / or, the aeration time is 240 to 480 minutes.

[0023] According to an embodiment of the present application, the precipitation time in the plurality of cycles shows a trend of first gradually decreasing and then remaining constant;

[0024] And / or, the duration of each cycle is 8 to 12 hours.

[0025] According to an embodiment of the present application, the precipitation time is 5-30 minutes.

[0026] According to an embodiment of the present application, the process of the bacteria-algae symbiosis forming bacteria-algae particles is carried out under conditions of alternating light and darkness, and the illumination adopts an LED light source, and the light intensity of the LED light source is 10,000 to 15,000 lux.

[0027] According to an embodiment of the present application, the illumination time is the same as the darkness time.

[0028] Compared with the prior art, the beneficial effects of this application include:

[0029] The method of the present application can cultivate bacteria and algae particles, which can use dissolved methane as an electron donor to provide electrons for denitrification, thereby achieving the purpose of simultaneous removal of dissolved methane and denitrification, and optimizing the denitrification process. The present application can also fix dissolved methane and carbon dioxide produced by aerobic respiration metabolism of microorganisms in sewage treatment plants, and can also fix or remove methane and carbon dioxide in biogas. Specifically, methane can be converted into organic matter and fixed in bacteria and algae particles by methane oxidizing bacteria under aerobic conditions; methane can also be anaerobically oxidized under anaerobic conditions, and provide electrons for denitrifying bacteria as an electron donor to participate in the denitrification process. The removal of carbon dioxide is mainly through the photosynthesis of microalgae, wherein the carbon dioxide can be the carbon dioxide contained in the gas introduced by the present application, and can also be the carbon dioxide produced by microbial respiration. The present application can achieve the synergistic removal of methane and carbon dioxide in the sewage treatment process, optimize the sewage treatment process, and the method of the present application solves the problems of difficult removal of dissolved methane and high carbon emissions in the existing sewage treatment process, and also reduces the demand for carbon source addition in the sewage treatment process, providing an efficient and low-carbon solution for sewage treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0031] Figure 1 A diagram of the mechanism for achieving methane, carbon dioxide and nitrogen removal by the method of the present application;

[0032] Figure 2 This is a schematic diagram of the structure of the reactor of this application;

[0033] Figure 3 This is a comparison of the sludge morphology changes after 68 days and 90 days of inoculation of sewage and gas in Example 1;

[0034] Figure 4 is a graph showing the relative abundance of methyl oxidizing bacteria and methane oxidizing bacteria in the bacterial and algal particles cultured 68 days after inoculation with sewage and gas in Example 1;

[0035] Figure 5 is a graph showing the relative abundance of algae in the bacterial-algae pellets cultured 68 days after inoculation with sewage and gas in Example 1;

[0036] Figure 6 This is the distribution diagram of the main bacteria in the bacteria and algae particles cultured 68 days after inoculation with sewage and gas in Example 1;

[0037] Figure 7 is a curve diagram of the removal rate of TOC in sewage in Example 1;

[0038] Figure 8 is a graph showing the removal rate of ammonia nitrogen in sewage in Example 1;

[0039] Fig. 9 This is a graph showing the changes in carbon dioxide and methane in the gas during the operation of the system in Example 1.

[0040] Description of reference numerals:

[0041] 1-water inlet bucket, 2-peristaltic pump, 3-device body, 4-drainage bucket, 5-air bag, 6-air pump, 7-aeration head. DETAILED DESCRIPTION

[0042] As used herein:

[0043] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0044] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0045] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0046] In these examples, parts and percentages are by mass unless otherwise indicated.

[0047] "Parts by mass" refers to the basic unit of measurement for expressing the mass ratio of multiple components. 1 part can represent any unit mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that, unlike the mass parts, the sum of the mass of all components is not limited to 100 parts.

[0048] “And / or” is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0049] In order to better explain the technical solution provided by this application, before the embodiments, the technical solution is first described as a whole, as follows:

[0050] A biological method for synergistically fixing methane and carbon dioxide, comprising:

[0051] Mixing activated sludge with microalgae, continuously introducing gas, and forming a bacterial-algae symbiosis under continuous light conditions;

[0052] The bacteria-algae symbiosis is put into a reactor, sewage is pumped in, the gas is introduced, and the reactor is operated in a cycle of water inlet-aeration-sedimentation-drainage;

[0053] Wherein, the gas includes methane and carbon dioxide, and the sewage includes a carbon source, a nitrogen source and a phosphorus source.

[0054] The present application method can be used to culture bacteria and algae particles, refer to Figure 1, the bacteria and algae particles can purify sewage and methane. Specifically, the bacteria and algae particles include aerobic bacteria, anaerobic bacteria and microalgae. The aerobic bacteria include methane oxidizing bacteria and nitrifying bacteria, and the anaerobic bacteria include denitrifying bacteria. The anaerobic zone of the bacteria and algae particles can use dissolved methane as an electron donor for denitrifying bacteria to provide electrons for denitrification, thereby achieving the purpose of simultaneous removal of dissolved methane and denitrification. When there is light, the aerobic zone of the bacteria and algae particles can further oxidize methane into carbon dioxide through the action of methane oxidizing bacteria, and at the same time utilize the photosynthesis of microalgae to absorb carbon dioxide, thereby achieving the synergistic removal of methane and carbon dioxide in the sewage treatment process. The photosynthetic oxygen production of microalgae can also serve as a substrate for bacterial respiration. The method of the present application can not only effectively eliminate the hazards of dissolved methane, but also reduce the demand for external carbon sources in the denitrification process, reduce treatment costs and reduce carbon emissions, and provide a low-carbon and efficient solution for sewage treatment.

[0055] Specifically, in the bacterial and algae particles of the present application, methane-oxidizing bacteria (MOB) and nitrifying bacteria (NB) are in the aerobic zone of the particles, responsible for removing methane and ammonia nitrogen under aerobic conditions. Denitrifying bacteria (DNB) are in the anaerobic zone of the particles, using dissolved methane as an electron donor to provide electrons for denitrification, removing methane, nitrates, nitrites and organic matter in sewage. When illuminated, the microalgae in the bacterial and algae particles can convert carbon dioxide into oxygen through photosynthesis, thereby providing energy for aerobic methane oxidizing bacteria, heterotrophic bacteria, and nitrifying bacteria.

[0056] It should be noted that the methane oxidizing bacteria, nitrifying bacteria and denitrifying bacteria in the present application are cultured under the conditions of the present application.

[0057] like Figure 2As shown, the reactor includes a water inlet bucket 1, a peristaltic pump 2, a device body 3, a drainage bucket 4, an air bag 5, an air pump 6, and an aeration head 7. The peristaltic pump 2 is located between the water inlet bucket 1 and the device body 3. The water inlet bucket 1 is used to hold sewage, and the peristaltic pump 2 is used to transport the sewage in the water inlet bucket 1 to the device body 3. A drainage port is provided in the middle of the reactor, and the drainage port is connected to the drainage bucket 4 through a conveying pipe. The drainage bucket 4 is used to hold treated sewage. The reactor also includes an aeration pipe, at least part of which is arranged inside the device body 3, and the central axis of the aeration pipe is parallel to or coincides with the central axis of the device body 3. One end of the exposure pipe is located at the bottom of the device body 3, and an aeration head 7 is provided at the end of the exposure pipe. The other end of the aeration pipe is connected to one end of the air pump 6, and the other end of the air pump 6 is connected to the air bag 5. The air bag 5 contains gas, and the air pump 6 is used to transport the gas in the air bag 5 to the device body 3 through the exposure pipe and the aeration head 7. An air outlet is provided at the top of the device body 3, and the air outlet is used to discharge the treated gas. The air outlet is connected to the air bag 5 through a conveying pipeline.

[0058] An external light source is arranged at a position about 40 cm away from the device body 3, and the external light source is an LED light source.

[0059] Further, the air pump 6 includes an electromagnetic air compressor, and the aeration head 7 includes a sand core aeration head.

[0060] According to an embodiment of the present application, after cyclic operation in the manner of water intake-aeration-sedimentation-drainage, the bacteria-algae symbiont is transformed into bacteria-algae particles.

[0061] According to an embodiment of the present application, the gas further includes nitrogen;

[0062] Based on the total volume of the gas, the proportion of methane is 35-60%, the proportion of carbon dioxide is 15-45%, and the proportion of nitrogen is 15-30%.

[0063] Since dissolved methane is generated in the anaerobic tanks of actual sewage treatment plants, and carbon dioxide and nitrogen are produced during sewage treatment, the gas in the present application contains methane, carbon dioxide and nitrogen of the above composition, which can simulate the waste gas generated in the actual sewage treatment process.

[0064] According to some embodiments of the present application, based on the total volume of the gas, the proportion of methane can be 35%, 38%, 40%, 43%, 45%, 48%, 50%, 53%, 55%, 58%, 60% or any value between 35% and 60%.

[0065] According to some embodiments of the present application, based on the total volume of the gas, the proportion of the carbon dioxide can be 15%, 18%, 20%, 23%, 25%, 28%, 30%, 33%, 35%, 38%, 40%, 45% or any value between 15 and 45%.

[0066] According to some embodiments of the present application, based on the total volume of the gas, the proportion of the nitrogen may be 15%, 18%, 20%, 23%, 25%, 28%, 30% or any value between 15% and 30%.

[0067] According to an embodiment of the present application, the carbon source includes sodium acetate and glucose, the nitrogen source includes ammonium chloride, and the phosphorus source includes potassium dihydrogen phosphate;

[0068] And / or, the concentration of the sodium acetate is 200-800 mg / L, the concentration of the glucose is 100-400 mg / L, the concentration of the ammonium chloride is 20-90 mg / L, and the concentration of the potassium dihydrogen phosphate is 5-10 mg / L.

[0069] For example, the concentration of sodium acetate can be 200 mg / L, 300 mg / L, 400 mg / L, 500 mg / L, 600 mg / L, 700 mg / L, 800 mg / L or any value between 200 and 800 mg / L, the concentration of glucose can be 100 mg / L, 200 mg / L, 300 mg / L, 400 mg / L or any value between 100 and 400 mg / L, the concentration of ammonium chloride can be 20 mg / L, 30 mg / L, 40 mg / L, 50 mg / L, 60 mg / L, 70 mg / L, 80 mg / L, 90 mg / L or any value between 20 and 90 mg / L, and the concentration of potassium dihydrogen phosphate can be 5 mg / L, 6 mg / L, 7 mg / L, 8 mg / L, 9 mg / L, 10 mg / L or any value between 5 and 10 mg / L.

[0070] According to the embodiment of the present application, the concentration of the activated sludge is 3000-4000 mg / L, and the concentration of the microalgae is 10 9 ~10 11 cells / L;

[0071] For example, the concentration of activated sludge can be 3000 mg / L, 3100 mg / L, 3200 mg / L, 3300 mg / L, 3400 mg / L, 3500 mg / L, 3600 mg / L, 3700 mg / L, 3800 mg / L, 3900 mg / L, 4000 mg / L or any value between 3000 and 4000 mg / L, and the concentration of microalgae can be 10 9Cells / L, 10 10 Cells / L, 10 11 Cells / L or 10 9 ~10 11 Any value between cells / L.

[0072] And / or, the continuous illumination time is 12 to 24 hours; the continuous illumination time can be 12 hours, 15 hours, 18 hours, 20 hours, 24 hours or any value between 12 and 24 hours.

[0073] And / or, the time of introducing gas is 12 to 24 hours. The time of introducing gas can be 12 hours, 15 hours, 18 hours, 20 hours, 24 hours or any value between 12 and 24 hours.

[0074] According to an embodiment of the present application, the microalgae includes Chlorella.

[0075] According to an embodiment of the present application, the light source of the continuous illumination is an LED lamp, and the illumination intensity of the continuous illumination is 10000-15000 lux. For example, the illumination intensity of the continuous illumination can be 10000 lux, 11000 lux, 12000 lux, 13000 lux, 14000 lux, 15000 lux, or any value between 10000-15000 lux.

[0076] According to an embodiment of the present application, the gas flow rate during aeration is 2.0 to 4.0 L / min; for example, the gas flow rate during aeration can be 2.0 L / min, 3.0 L / min, 4.0 L / min or any value between 2.0 and 4.0 L / min.

[0077] And / or, the aeration time is 240 to 480 minutes.

[0078] The aeration time may be 240 min, 250 min, 280 min, 300 min, 330 min, 350 min, 380 min, 400 min, 430 min, 450 min, 480 min or any value between 240 and 480 min.

[0079] According to the embodiments of the present application, the sedimentation time in the multiple cycles shows a trend of gradually decreasing, and then the sedimentation time remains constant. The present application can screen functional microorganisms by gradually shortening the sedimentation time, and cultivate slowly growing microorganisms by utilizing the biofilm attachment benefits, thereby forming a bacterial-algae particle system with high biomass, good sedimentation performance, and synergistic growth of multiple microorganisms. It can significantly improve the physical strength of the bacterial-algae particles, accelerate the granulation process of the bacterial-algae particles, thereby enhancing the removal efficiency of the bacterial-algae particles for soluble methane and nutrients in sewage, and ensure the stability of the system operation. This operating mode realizes the role of the bacterial-algae particles as denitrification electron donors under anaerobic conditions, and at the same time, through methane oxidation and microalgae absorption under aerobic conditions, synergistically removes methane and carbon dioxide, providing an efficient and low-carbon solution for sewage treatment.

[0080] According to an embodiment of the present application, the duration of each cycle is 8 to 12 hours. For example, the duration of each cycle can be 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, or any value between 8 and 12 hours.

[0081] According to an embodiment of the present application, the precipitation time is 5-30 minutes.

[0082] The precipitation time can be 5 min, 8 min, 10 min, 13 min, 15 min, 18 min, 20 min, 23 min, 25 min, 28 min, 30 min or any value between 5 and 30 min.

[0083] According to the embodiment of the present application, the process of the bacteria-algae symbiont forming bacteria-algae particles is carried out under the condition of alternating light and darkness, and the light is an LED light source, and the light intensity of the LED light source is 10000-15000 lux. By adopting the light-dark alternation method, an alternating aerobic and anaerobic environment can be provided in the reactor, providing good conditions for the growth of various functional microorganisms.

[0084] For example, the light intensity of the LED light source may be 10,000 lux, 11,000 lux, 12,000 lux, 13,000 lux, 14,000 lux, 15,000 lux, or any value between 10,000 and 15,000 lux.

[0085] According to an embodiment of the present application, the illumination time is the same as the darkness time.

[0086] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If specific conditions are not specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0087] The activated sludge used in the following examples was taken from the biochemical pool of Longwangzui Sewage Treatment Plant. The methane oxidizing bacteria, nitrifying bacteria and denitrifying bacteria in this application were cultured under the conditions of this application.

[0088] Example 1

[0089] Example 1 provides a biological method for the synergistic fixation of methane and carbon dioxide. Figure 2 The reactor shown in the figure is carried out, specifically comprising:

[0090] (1) Mixing activated sludge with Chlorella, continuously introducing gas, and forming a bacterial-algal symbiosis under continuous light conditions;

[0091] The gases include 31.29% carbon dioxide by volume, 52.63% methane by volume, and 16.08% nitrogen by volume.

[0092] The concentration of activated sludge is 4000 mg / L, and the concentration of Chlorella is 10 9 cells / L;

[0093] The continuous illumination time was 12 hours, alternating between 12 hours of light and 12 hours of darkness;

[0094] The gas is passed through for 24 hours, after which the air bag is replaced.

[0095] The light source for continuous lighting is a 24W LED lamp with a color temperature of 5600K and a light intensity of 12000lux.

[0096] (2) placing the bacteria-algae symbiont into a reactor, pumping in sewage and introducing gas, and operating the reactor in a cycle of water inlet-aeration-sedimentation-drainage;

[0097] Sewage is added into the water inlet bucket 1 every day, and the sewage includes 200 mg / L of sodium acetate and 100 mg / L of glucose, 50 mg / L to 90 mg / L of ammonium chloride, and 5 mg / L of potassium dihydrogen phosphate.

[0098] 2L of gas is taken out and put into the air bag every day. The gas includes 31.29% carbon dioxide by volume, 52.63% methane by volume, and 16.08% nitrogen by volume.

[0099] When the reactor starts to run, the peristaltic pump 2 is used to pressurize the sewage, and the sewage is pushed into the device body 3. The system volume exchange rate is 50%, each cycle is 8h, the hydraulic retention time is 16 hours, and 3 cycles are run per day. The water intake is 5min, the sedimentation time is 30min at the initial stage of the experiment, the sedimentation time is gradually reduced to 5min, and then the sedimentation time is kept constant at 5min, and the drainage is 5min. Except for the sedimentation time and the water intake and drainage time, the rest of the time is aeration time. During aeration, the gas in the air bag is extracted by the air pump 6 and pumped into the aeration head 7 in the device body 3 for uniform aeration. The gas flow rate during aeration is 2.0L / min; after an 8h cycle, the effluent is discharged from the drain port set in the middle of the reactor. The external light source is the LED lamp used in step (1), which is a 24W LED lamp with a color temperature of 5600K and a light intensity of 12000lux. Step (2) is carried out under the condition of alternating light and darkness, alternating between 12 hours of light and 12 hours of darkness.

[0100] The purified sewage is discharged from the middle drainage port of the device body 3 and enters the drainage bucket 4.

[0101] Figure 3 The left picture shows the sludge morphology after 68 days of inoculation with sewage and gas. Figure 3 The figure on the right shows the sludge morphology after 90 days of inoculation with sewage and gas. Figure 3 It can be seen that under the conditions of Example 1, the bacteria and algae particles matured on the 68th day, at which time obvious dark green particles appeared in the reactor. When the operation reached 90 days, the shape of the bacteria and algae particles tended to be irregular round dark green particles, the particle surface was smoother, and the number of particles increased compared to the 68th day.

[0102] Figure 4 is a relative abundance diagram of methyl oxidizing bacteria and methane oxidizing bacteria in the bacterial and algal particles cultured 68 days after inoculation with sewage and gas in Example 1, Figure 4 It can be seen that the bacterial and algal particles contain aerobic methane oxidizing bacteria and methyl oxidizing bacteria, which can effectively promote the removal of methane.

[0103] Figure 5 is a graph showing the relative abundance of algae in the bacterial-algae particles cultured 68 days after inoculation with sewage and gas in Example 1. Figure 5 It can be seen that the algae in the bacteria-algae granules are mainly Chlorella.

[0104] Figure 6 This is the distribution diagram of the main bacteria in the algae particles cultured after the 68th day of inoculation of sewage and gas in Example 1. Figure 6 The top 20 bacteria in relative abundance are listed, by Figure 6It can be seen that the main bacteria in the bacterial-algae granules include typical anaerobic bacteria Lactococcus, denitrifying bacteria Brevundimonas, aerobic bacteria Delftia and other bacteria.

[0105] During the entire operation process, the growth of bacteria and algae particles and the removal effect of pollutants in simulated wastewater can be judged by the removal effect of TOC and nitrogen. Figure 7 It can be seen that the bacteria and algae particles have a good TOC removal effect during operation, and the TOC removal rate is always stable at more than 90%. Figure 8 It can be seen that the bacteria and algae particles have a good ammonia nitrogen removal effect during operation, and the ammonia nitrogen removal rate is stable at more than 95%. As time goes by, after the concentration of ammonia nitrogen is increased to 90 mg / L, the ammonia nitrogen removal rate drops to more than 80%. The bacteria and algae particles cultivated by the method of the present application can effectively degrade sewage, and the high pollutant removal rate proves that the bacteria and algae particles grow well in sewage.

[0106] During the entire operation process, the changes in gas components in the gas can be used to determine the absorption capacity of the algae particles for methane and carbon dioxide in the gas. Fig. 9 As shown in the figure, the system has a good carbon dioxide removal effect during operation. At the end of three water inlet and outlet cycles, that is, when the system was running for 24 hours, the average carbon dioxide component was 22.93%. Compared with the initial carbon dioxide percentage of 31.29%, the algae particles absorbed 8.36% of the carbon dioxide. Similarly, at the beginning of the reaction, the proportion of methane in the air bag reached 52.63%, while at the end of the reaction, the proportion of methane in the air bag decreased to 31.22%, and the algae particles absorbed 21.41% of the methane. The system achieved the fixation of carbon dioxide and methane in the gas during operation, proving that the algae particles have the ability to remove dissolved methane and carbon dioxide produced in the sewage treatment process.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0108] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the above claims, any one of the claimed embodiments may be used in any combination. The information disclosed in this background technology section is intended only to deepen the understanding of the overall background technology of the present application and should not be regarded as an admission or in any form of implication that the information constitutes prior art known to those skilled in the art.

Claims

1. A biological method for the synergistic fixation of methane and carbon dioxide, characterized in that: include: Mixing activated sludge with microalgae, continuously introducing gas, and forming a bacterial-algae symbiosis under continuous light conditions; The bacteria-algae symbiosis is put into a reactor, sewage is pumped in, the gas is introduced, and the reactor is operated in a cycle of water inlet-aeration-sedimentation-drainage; Wherein, the gas includes methane and carbon dioxide, and the sewage includes a carbon source, a nitrogen source and a phosphorus source.

2. The biological method for synergistically fixing methane and carbon dioxide according to claim 1, characterized in that: After the cycle of water intake-aeration-sedimentation-drainage is carried out, the bacteria-algae symbiont is transformed into bacteria-algae particles.

3. The biological method for synergistically fixing methane and carbon dioxide according to claim 1, characterized in that: The gas also includes nitrogen; Based on the total volume of the gas, the proportion of methane is 35-60%, the proportion of carbon dioxide is 15-45%, and the proportion of nitrogen is 15-30%.

4. The biological method for synergistically fixing methane and carbon dioxide according to claim 1, characterized in that: The carbon source includes sodium acetate and glucose, the nitrogen source includes ammonium chloride, and the phosphorus source includes potassium dihydrogen phosphate; And / or, the concentration of the sodium acetate is 200-800 mg / L, the concentration of the glucose is 100-400 mg / L, the concentration of the ammonium chloride is 20-90 mg / L, and the concentration of the potassium dihydrogen phosphate is 5-10 mg / L.

5. The biological method for synergistically fixing methane and carbon dioxide according to claim 1, characterized in that: The concentration of the activated sludge is 3000-4000 mg / L, and the concentration of the microalgae is 10 9 ~10 11 cells / L; And / or, the continuous illumination time is 12 to 24 hours; And / or, the time of introducing gas is 12 to 24 hours; and / or, the microalgae comprises Chlorella; And / or, the light source of the continuous illumination is an LED lamp, and the illumination intensity of the continuous illumination is 10000-15000 lux.

6. The biological method for synergistically fixing methane and carbon dioxide according to claim 1, characterized in that: The gas flow rate during aeration is 2.0 to 4.0 L / min; And / or, the aeration time is 240 to 480 minutes.

7. The biological method for synergistically fixing methane and carbon dioxide according to claim 1, characterized in that: The precipitation time in the plurality of cycles shows a trend of first gradually decreasing and then remaining constant; And / or, the duration of each cycle is 8 to 12 hours.

8. The biological method for synergistically fixing methane and carbon dioxide according to claim 7, characterized in that: The precipitation time is 5-30 min.

9. The biological method for synergistically fixing methane and carbon dioxide according to any one of claims 1 to 8, characterized in that: The process of the bacteria-algae symbiosis forming bacteria-algae particles is carried out under the condition of alternating light and darkness. The light is an LED light source, and the light intensity of the LED light source is 10000-15000 lux.

10. The biological method for synergistically fixing methane and carbon dioxide according to claim 9, characterized in that: The duration of the light exposure is the same as the duration of the darkness.

Images