Preparation method of bacteria-algae symbiotic filler and filler combination structure based on the bacteria-algae symbiotic filler

Abstract

The application discloses a kind of preparation methods of bacteria-algae symbiosis filler, specifically: to the reactor filled with filler, add active sludge dispersion liquid, under aeration condition, 7-10 days are operated, and simulate tail water is passed through during operation process;Then inoculate chlorella according to the volume ratio of active sludge dispersion liquid and chlorella dispersion liquid 1:5-50, 22-30 DEG C and under illumination, 14-20 days are operated, wherein, light dark ratio is: illumination 6-12h, dark 12-18h;Simulate sewage plant tail water is passed through during operation process;Get the filler that hangs bacteria-algae symbiosis biofilm.The bacteria-algae symbiosis film formed in the application, microalgae can promote the enrichment of denitrifying bacteria and organic matter metabolic functional bacteria, and bacteria can improve the photosynthesis performance and carbon fixation performance of microalgae through material exchange and information transmission, so that the bacteria-algae symbiotic system can efficiently purify N / P / organic matter in water body, while reducing greenhouse gas emissions.The application also discloses a filler combination structure based on the above bacteria-algae symbiotic filler.

Description

Technical Field

[0001] The present invention relates to a method for preparing a bacteria-algae symbiotic filler, and also relates to a filler combination structure based on the bacteria-algae symbiotic filler. Background Art

[0002] In the water pollution control industry, traditional treatment technologies have drawbacks such as high energy consumption, high costs, and greenhouse gas emissions (e.g., CO2, N2O, CH4) during water treatment. Microalgae have the potential to treat wastewater and fix CO2. Microalgae utilize nitrogen, phosphorus, and CO2 in wastewater as raw materials, releasing O2 through photosynthesis to promote aerobic degradation of pollutants, thereby achieving simultaneous wastewater treatment and CO2 fixation. However, single microalgae systems have poor sedimentation, are easily lost with tailwater, are significantly affected by the external environment, and have weak risk tolerance, limiting their application. Summary of the Invention

[0003] Purpose of the Invention: This invention aims to provide a method for preparing a bacterial-algal symbiotic filler. This method generates a bacterial-algal biofilm on the filler. This bacterial-algal symbiotic system not only exhibits good sedimentation and risk resistance, but also improves wastewater treatment. Another purpose of the invention is to provide a filler assembly structure based on the aforementioned bacterial-algal symbiotic filler, which can be applied to a reactor for wastewater treatment.

[0004] Technical solution: The preparation method of the bacteria-algae symbiotic filler described in the present invention is specifically as follows: adding an activated sludge dispersion to a reactor filled with filler, operating under aeration conditions for 7 to 10 days, and introducing simulated tail water during the operation; then inoculating Chlorella according to a volume ratio of 1:5 to 50 between the activated sludge dispersion and the Chlorella dispersion, and operating at 22 to 30°C and light for 14 to 20 days, wherein the light-dark ratio is: light for 6 to 12 hours and darkness for 12 to 18 hours; introducing simulated sewage plant tail water during the operation; the activated sludge and microalgae adhere to form a biofilm in the order of inoculation, and obtain filler with a bacteria-algae symbiotic biofilm.

[0005] The method of the present invention adopts a biofilm-forming method of first inoculating sludge to form a bacterial biofilm on the surface of the filler, and then inoculating microalgae to form a bacterial-algae symbiotic biofilm. That is, the microalgae will adhere to the first formed bacterial biofilm to form a microalgae biofilm (bacteria-algae symbiotic biofilm).

[0006] It takes 7 to 10 days for bacterial biofilm to form on the filler. The bacterial biofilm is formed first, and then algae are inoculated to form the bacterial-algal biofilm. The total biofilm maturity time is 21 to 30 days.

[0007] The activated sludge was acclimated and cultured. The acclimation process for activated sludge was as follows: the sludge used in this study was obtained from the secondary sedimentation tank of a sewage treatment plant in Jiangning District, Nanjing City, Jiangsu Province. After sludge retrieval, it was first sieved through a 1mm×1mm mesh to remove large particles. After gravity settling for 24 hours, the supernatant was removed and the sludge was washed three times with tap water before being allowed to stand for use. After washing, the sludge was aerated for 24 hours (air aeration) under conditions of controlling the pH at 7.5-8.5 and the water temperature at 25-30°C. The sludge was then diluted to a MLSS concentration of 100-500 mg / L. Simulated tailwater was then introduced for acclimation with a Chlorella dispersion at an initial concentration of 1:1 sludge dispersion and aeration continued for 3-7 days to obtain the acclimated activated sludge. The domesticated activated sludge is more likely to adhere to the surface of the filler to form a bacterial biofilm, which is also conducive to the mutual adhesion and harmonious symbiosis of the bacterial biofilm and the subsequently inoculated microalgae cells. Directly inoculating undomesticated sludge into the reactor and then inoculating Chlorella can easily cause the death of a large number of Chlorella.

[0008] Among them, continuous aeration is performed for 3 to 7 days to maintain the dissolved oxygen (DO) concentration at 0.8 to 1.8 mg / L.

[0009] Wherein, the filler is a hollow cylindrical MBBR filler; the material of the filler is polyethylene.

[0010] The filling rate of the filler in the reactor is 30-50%.

[0011] The water inlet and outlet of the reactor are operated in a bottom-in and top-out mode.

[0012] Wherein, a water distribution orifice plate is provided at the water inlet of the reactor.

[0013] Among them, the formula of simulated tail water is: each liter of simulated tail water contains the following concentrations of substances: sodium acetate 64 mg / L, ammonium chloride 19.11 mg / L, potassium dihydrogen phosphate 2.20 mg / L, sodium nitrate 60.71 mg / L, magnesium sulfate 30 mg / L, calcium chloride 20 mg / L, EDTA (ethylenediaminetetraacetic acid) 1.0 mg / L and trace element solution 1 mL / L.

[0014] Among them, each liter of trace element solution contains the following concentrations of substances: boric acid 1.8 mg / L, ferric chloride 12 mg / L, copper sulfate 0.2 mg / L, manganese sulfate 1.2 mg / L, sodium molybdate 0.6 mg / L, zinc sulfate 1.5 mg / L, cobalt chloride 1.6 mg / L and potassium iodide 1.5 mg / L; the solvent for preparing the trace element solution is water.

[0015] The initial concentration of the activated sludge dispersion is 100-500 mg / L; the initial concentration of the Chlorella dispersion is 100-500 mg / L; and the initial concentrations of the two during inoculation are the same.

[0016] The filler combination structure based on the above-mentioned bacteria-algae symbiotic filler includes multiple porous spherical shells with bacteria-algae symbiotic fillers inside, and the multiple porous spherical shells are connected in series in any combination through connecting rods or connecting lines.

[0017] Wherein, the filling rate of the biofilm filler in the porous spherical shell is 30% to 70%.

[0018] The size of the through holes on the porous spherical shell is smaller than that of the biofilm filler, and the mesh holes on the spherical shell are rectangular (8 to 16 mm in length and 16 mm in width). The material of the spherical shell is polypropylene.

[0019] The present invention uses a method of first inoculating sludge and then inoculating microalgae to form a biofilm of bacteria and algae, thereby improving the pollution reduction and carbon reduction capabilities of microalgae and preventing them from being lost with water. The biofilm is formed by using fillers to prevent the fillers from being lost with water and external water flow and pollutants from damaging the biofilm on the surface of the fillers. The biofilm is then applied to ecological water bodies to improve treatment efficiency and reduce greenhouse gas emissions. The present invention promotes the adhesion and growth of microalgae on the surface of the bacterial biofilm by pre-acclimating the bacterial community to form a symbiotic biofilm of bacteria and algae, thereby preventing the loss of microalgae with water and improving the risk resistance of the symbiotic system of bacteria and algae. Among them, the bacterial community is used to improve the photosynthetic performance of microalgae and improve the photosynthetic carbon fixation capacity of microalgae; while the microalgae assimilate and absorb nutrients in the ecological water body, they photosynthesize and release oxygen to supply the bacterial community with nutrients such as organic matter for decomposition and metabolism. The microalgae promote the enrichment of functional bacterial communities such as nitrogen and phosphorus, organic matter metabolism and EPS secretion, thereby improving the pollution reduction and carbon reduction capabilities of the overall filler system for the water body.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0021] (1) In the bacteria-algae symbiotic membrane formed by the present invention, microalgae can promote the enrichment of denitrification and phosphorus removal bacteria and organic matter metabolism functional bacteria. Bacteria can improve the photosynthetic performance and carbon fixation performance of microalgae through pathways such as material exchange and information transmission, so that the bacteria-algae symbiotic system can efficiently purify N / P / organic matter in water bodies and reduce greenhouse gas emissions.

[0022] (2) In the process of forming the bacteria-algae symbiotic film, the present invention adopts the method of first inoculating sludge and then inoculating microalgae to form a biofilm of bacteria and algae, which can effectively overcome the disadvantage that microalgae are easily lost with water, improve the sedimentation and risk resistance of the bacteria-algae symbiotic system, and at the same time, compared with the simultaneous formation of bacteria and algae, this method of forming a biofilm can further improve the pollution reduction and carbon reduction capabilities of the bacteria-algae symbiotic system.

[0023] (3) The fillers with the symbiotic membrane of bacteria and algae are assembled to form a filler combination structure, which can further prevent the disadvantage of microalgae being easily lost in ecological water bodies, so that the fillers with the symbiotic membrane of bacteria and algae can continue to exist in the ecological water body and exert their pollution reduction and carbon reduction capabilities. At the same time, it can also prevent external water flow and pollutants from destroying the symbiotic membrane of bacteria and algae on the fillers in the spherical shell; finally, the microalgae release oxygen through photosynthesis, which helps to improve the self-purification ability of the water body. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of one of the combined structures of the bacteria-algae symbiotic filler assembled into a filler combination;

[0025] Figure 2 Schematic diagram of the structure of the reactor in the process of forming the bacteria-algae symbiotic filler;

[0026] Figure 3 This is a physical picture of the hollow cylindrical MBBR filler;

[0027] Figure 4 This is a physical picture of a spherical shell;

[0028] Figure 5 The carbon fixation performance of fillers obtained by different cultivation methods;

[0029] Figure 6 The removal effects of N, P and organic matter on fillers obtained by different cultivation methods;

[0030] Figure 7 This is a photo of the filler combination formed by the bacteria-algae symbiotic filler of Example 1 being applied to a gallery bioreactor;

[0031] Figure 8 The carbon fixation effect of fillers with different hydraulic retention times in gallery bioreactors was compared.

[0032] Figure 9 Comparison of COD removal effects with different hydraulic retention times in gallery bioreactors;

[0033] Figure 10 The comparison of ammonia nitrogen removal effects with different hydraulic retention times in gallery bioreactors;

[0034] Figure 11 The comparison of total nitrogen removal effects at different hydraulic retention times in gallery bioreactors;

[0035] Figure 12 The comparison of total phosphorus removal effects at different hydraulic retention times in gallery bioreactors;

[0036] Figure 13Schematic diagram of the filler combination structure used in the gallery bioreactor of Example 2. DETAILED DESCRIPTION

[0037] Figure 2 The continuous flow biofilm reactor of the present invention has a water inlet at the bottom of the reactor, a water distribution orifice plate at the water inlet, and a water outlet at the top of the reactor. Therefore, the water inlet and outlet of the reactor are operated in a bottom-in and top-out mode; multiple aeration stones are placed in the reactor, and the aeration stones are connected to an external air pump through an air pipe.

[0038] Example 1

[0039] The preparation method of the bacteria-algae symbiotic filler of the present invention is specifically as follows:

[0040] Will Figure 3 The hollow cylindrical MBBR filler (25 mm in diameter) shown in the figure was added to a continuous flow biofilm reactor with a filling rate of 30% (v / v), that is, the filling volume of the filler was 30% of the reactor volume; an activated sludge dispersion with an initial concentration of 100 mg / L was added to the reactor, and the reactor was operated under aeration conditions for 10 days. During the operation, simulated tail water was introduced; then, the activated sludge dispersion and the Chlorella dispersion (the initial concentration of the Chlorella dispersion was 100 mg / L) were inoculated at a volume ratio of 1:50. Chlorella, control the temperature at 25-30°C, wrap plant growth light strips around the reactor, set the timer to start lighting at 7:00 am every day and end the simulation at 7:00 pm, ensuring 12 hours (light): 12 hours (darkness); run for 18 days, and introduce simulated tail water during the operation; obtain filler with bacterial and algal symbiotic biofilm; to ensure that the filler in the reactor is in a suspended state, the reactor water inlet adopts the "bottom-in and top-out" operation mode, and the simulated tail water is sucked to the water inlet at the bottom of the reactor by a peristaltic pump.

[0041] After the biofilm in the reactor is mature and stable (the total maturation time is 28 days), the original operating conditions are maintained unchanged. The CO2 gas flux and the inlet and outlet water quality (COD, NH4 + -N, TN, TP), the test results are as follows Figures 5-6 shown.

[0042] Wherein, in Example 1, the activated sludge is an activated sludge that has been acclimated, and the acclimation and cultivation process of the activated sludge is as follows: the sludge used in this study was taken from the secondary sedimentation tank of a sewage treatment plant in Jiangning District, Nanjing City, Jiangsu Province. After the sludge was retrieved, it was first sieved through a sieve (1mm×1mm) to remove large particle impurities, and the supernatant was removed after gravity sedimentation for 24 hours. Then, tap water was added to wash it three times and then it was allowed to stand for use. After the sludge was washed, the pH was controlled to be 7.5-8.5 and the water temperature was 25-30°C. The sludge was aerated for 24 hours (air aeration), and then the sludge concentration was diluted to MLSS of 100 mg / L. The chlorella dispersion with the same initial concentration of chlorella dispersion was added at a volume ratio of 1:1 to the sludge dispersion, and the simulated tail water was introduced for acclimation. The aeration was continued for 3-7 days (the dissolved oxygen concentration in the simulated tail water during the aeration process was 0.8-1.5 mg / L) to obtain the acclimated activated sludge.

[0043] Comparative Example 1

[0044] Comparative Example 1 uses the same continuous flow film forming reactor as Example 1. Figure 3 The hollow cylindrical MBBR filler (25 mm in diameter) shown was added to a continuous flow biofilm reactor with a filling rate of 30% (v / v); only Chlorella was inoculated into the reactor, and the same volume of Chlorella dispersion with an initial concentration of 100 mg / L as in Example 1 was added. The temperature was controlled at 25-30°C, and a plant growth light strip was wrapped around the reactor. A timer was set to start illumination at 7:00 am and end the simulation at 7:00 pm every day, ensuring a 12-h (light): 12-h (dark) cycle. The reactor was operated for 28 days, during which simulated tail water was introduced. Chlorella adhered to the surface of the filler to obtain a filler with a microalgae biofilm.

[0045] After the biofilm in the reactor is mature and stable (the total maturation time is 28 days), the original operating conditions are maintained unchanged. The CO2 gas flux and the inlet and outlet water quality (COD, NH4 + -N, TN, TP), the test results are as follows Figures 5-6 shown.

[0046] Comparative Example 2

[0047] Comparative Example 1 uses the same continuous flow film forming reactor as Example 1. Figure 3The hollow cylindrical MBBR filler (25 mm diameter) shown was added to a continuous flow biofilm reactor at a fill rate of 30% (v / v). The reactor was inoculated with both bacterial and algal solutions, i.e., activated sludge dispersion and Chlorella dispersion were added simultaneously at a volume ratio of 1:50, with an initial inoculum concentration of 100 mg / L. The volumes of each added were the same as in Example 1. The temperature was maintained at 25-30°C, and plant growth light strips were wrapped around the reactor. A timer was set to start illumination at 7:00 AM and end at 7:00 PM daily, ensuring a 12-hour light cycle: 12-hour dark cycle. The reactor was operated for 28 days, with simulated tailwater introduced during operation. The simultaneously inoculated bacteria and microalgae adhered to the filler surface, resulting in a filler with bacterial and algal biofilm. The activated sludge in Comparative Example 2 was also acclimated using the same method as in Example 1.

[0048] After the biofilm in the reactor is mature and stable (the total maturation time is 28 days), the original operating conditions are maintained unchanged. The CO2 gas flux and the inlet and outlet water quality (COD, NH4 + -N, TN, TP), the test results are as follows Figures 5-6 shown.

[0049] like Figure 5 As shown in the figure, the CO2 gas flux of the pure algae system in Comparative Example 1 is only -69.43 mg / m 2 / d, after the activated sludge was inoculated and mixed with biofilm, the CO2 fixation performance of the bacteria-algae synchronous system of comparative example 2 and the bacteria-first-then-algae system of example 1 were both enhanced, and the CO2 gas flux of the two increased to -108.32 mg / m 2 / d and -119.98 mg / m 2 / d, CO2 fixation rate also increased from 20.04% to 31.50% and 35.30%. The results show that adding a small amount of activated sludge can promote the absorption of CO2 by Chlorella, and the biofilm formation method of bacteria first and algae later is more conducive to improving the CO2 fixation efficiency of the bacterial-algal symbiotic system. Different biofilm formation methods also have a significant impact on the purification efficiency of sewage treatment plant tail water ( Figure 6 ). Compared with the pure algae system, the COD removal rates of the bacteria-algae synchronous system and the bacteria-first-then-algae system increased from 51.57% to 56.54% and 62.33% respectively, and the TP removal rates increased from 74.92% to 78.79% and 84.23% respectively. The effluent quality meets the "Surface Water Environmental Quality Standard" (GB 3838-2002) Class IV (COD ≤ 30 mg / L, TP ≤ 0.3 mg / L). The bacteria-algae synchronous system and the bacteria-first-then-algae system have a significant impact on the removal of NH4 + -N and TN removal rates were significantly improved, and NH4 +The removal rate of -N increased from 50.14% to 83.66% and 89.44%, and the removal rate of TN increased from 43.09% to 64.97% and 66.93%. This shows that the biofilm formation method of first forming bacteria and then forming algae in the present invention can greatly improve the pollution reduction performance of the bacterial and algal symbiotic filler.

[0050] The formula of the simulated tail water used in Example 1 and Comparative Examples 1 to 2 is (the water quality of the simulated tail water refers to the "Pollutant Discharge Standard for Urban Wastewater Treatment Plants" (GB 18918-2002) Level A): per liter of simulated tail water, the following concentrations of substances are contained: sodium acetate 64 mg / L, ammonium chloride 19.11 mg / L, potassium dihydrogen phosphate 2.20 mg / L, sodium nitrate 60.71 mg / L, magnesium sulfate 30 mg / L, calcium chloride 20 mg / L, EDTA (ethylenediaminetetraacetic acid) 1.0 mg / L and trace element solution 1 mL / L. The following concentrations of substances are contained in each liter of trace element solution: boric acid 1.8 mg / L, ferric chloride 12 mg / L, copper sulfate 0.2 mg / L, manganese sulfate 1.2 mg / L, sodium molybdate 0.6 mg / L, zinc sulfate 1.5 mg / L, cobalt chloride 1.6 mg / L and potassium iodide 1.5 mg / L; the solvent for preparing the trace element solution is water.

[0051] like Figure 1 As shown, the filler combination structure based on the bacteria-algae symbiotic filler of Example 1 includes multiple porous spherical shells filled with bacteria-algae symbiotic fillers, and the multiple porous spherical shells are connected in series in any combination through connecting rods or connecting lines.

[0052] Example 2

[0053] like Figure 13 As shown, a filler combination structure is prepared based on the bacteria-algae symbiotic filler in Example 1. The filler combination structure includes multiple porous spherical shells with bacteria-algae symbiotic fillers inside. The multiple porous spherical shells are connected in series by connecting rods, and the spacing between adjacent porous spherical shells is 40 mm; wherein, the filling rate of biofilm filler in the porous spherical shells is 50%.

[0054] The above-mentioned filler combination was added to the gallery bioreactor, and three parallel experiments were carried out. The hydraulic retention time (HRT) of the three gallery-type bacteria and algae bioreactors was set to 12h, 24h, and 48h, respectively, to investigate the pollution reduction and carbon reduction effects of the three reactors with different HRT.

[0055] The corridor reactor is made of organic glass, 570mm long, 240mm wide and 140mm high. There are four parallel corridors in the middle, each 460mm long, 40mm wide and 80mm high. There is a 30mm connecting area between two adjacent corridors for water to flow through.

[0056] The above filler combination is added to each corridor of the reactor to construct a corridor-type bacteria-algae bioreactor (such as Figure 7 The reactor was fed by the first corridor on the left and discharged by the first corridor on the right. The inlet and outlet pipes were 20 mm long and 10 mm in outer diameter. A 50 mm long water baffle, 30 mm from the bottom, was installed 30 mm from the inlet to reduce water erosion on the bacterial-algal symbiotic filler. The CO2 gas emission flux was measured using a static chamber-gas chromatography method.

[0057] The CO2 fixation of gallery-type algae bioreactors with different HRTs is shown in the figure. Figure 8 The CO2 fixation performance of the reactors with different HRTs increased with the increase of operation time, and the CO2 gas flux of the emission reduction reached the maximum on the 20th day. On the 20th day, the CO2 gas flux of the gallery-type algae bioreactor with an HRT of 12h was -121.27mg / m 2 / d, the CO2 gas flux in the reactor with a HRT of 24h increased to -402.89mg / m 2 / d. The CO2 gas flux in the reactor with HRT of 48h was -267.23mg / m 2 The results showed that the gallery-type bacteria-algae bioreactor with a HRT of 24h had the best CO2 fixation performance.

[0058] The removal efficiency of COD in gallery-type algae bioreactors with different HRT is as follows Figure 9 As shown in the figure. The COD removal efficiency of the different HRT reactors increased with the increase in operation time, reaching the highest COD removal efficiency on the 20th day of operation, and the effluent met the "Surface Water Environmental Quality Standard" (GB 3838-2002) Class IV (COD ≤ 30 mg / L). However, there were significant differences in the COD removal efficiency of the gallery-type algae bioreactors with different HRTs. For example, on the 20th day, the COD removal rate of the reactor with an HRT of 12 hours was only 61.82%, and the effluent COD was 21.65 mg / L. The COD removal rate of the reactor with an HRT of 24 hours further increased to 68.85%, and the effluent COD was 17.67 mg / L, meeting the "Surface Water Environmental Quality Standard" (GB 3838-2002) Class III (COD ≤ 20 mg / L).

[0059] Figure 10 The results of different HRT corridor-type algae bioreactors on NH4 + -N removal efficiency. The gallery-type bacteria-algae bioreactors with different HRTs operated efficiently and stably during the test period. The gallery-type bacteria-algae bioreactor with an HRT of 12h had a NH4 + -N removal rate is 49.58% to 59.49%, HRT is 24h and 48h reactor NH4 +-N removal rate is stable at 96.71% to 99.38%. Compared with the reactor with HRT of 12h, the NH4 + The -N removal effect is significantly improved, meeting the "Surface Water Environmental Quality Standard" (GB 3838-2002) Class II (NH4+-N≤0.5mg / L).

[0060] The removal efficiency of TN by gallery-type algae bioreactors with different HRT is as follows Figure 11 As shown in the figure, TN removal efficiency in gallery-type algae bioreactors with different HRTs increased with operating time, reaching its highest efficiency on the 20th day of operation. However, significant differences in TN removal efficiency were observed between gallery-type algae bioreactors with different HRTs. For example, on the 20th day, the TN removal efficiency of the reactor with a 12-hour HRT was only 33.80%, with TN in the effluent at 9.06 mg / L. However, the TN removal efficiency in the reactors with 24-hour and 48-hour HRTs increased to 48.58% and 48.51%, respectively.

[0061] The removal efficiency of TP in gallery-type algae bioreactors with different HRTs is as follows: Figure 12 As shown in the figure, TP removal efficiency in gallery-type algae bioreactors with different HRTs increased with operating time, reaching its highest efficiency on the 20th day, with the effluent meeting Class III (TP ≤ 0.2 mg / L) of the Environmental Quality Standard for Surface Water (GB 3838-2002). Significant differences in TP removal efficiency were observed among gallery-type algae bioreactors with different HRTs. Specifically, on the 20th day, the TP removal efficiency of the gallery-type algae bioreactor with a 12-hour HRT was 92.00%, with an effluent TP of 0.05 mg / L. In the reactors with HRTs of 24 and 48 hours, the TP removal efficiency increased to 98.21% and 99.83%, respectively, with effluent TP of 0.011 and 0.002 mg / L, respectively, meeting Class II (TP ≤ 0.1 mg / L) of the Environmental Quality Standard for Surface Water (GB 3838-2002).

[0062] The corridor-type bacteria-algae bioreactor treats ecological water, achieving excellent results in removing nitrogen, phosphorus, and organic matter, as well as reducing greenhouse gas emissions. The simulated wastewater formulation used in Example 2 is the same as that in Example 1. This invention addresses the weak pollution and carbon reduction capabilities of single microalgae systems by combining bacteria and microalgae. On the one hand, the bacteria-algae cells metabolize and secrete EPS, which is used to adhere and aggregate the bacteria-algae cells together, forming a bacteria-algae biofilm, thereby improving the sedimentation and risk resistance of the bacteria-algae symbiotic system. On the other hand, the resulting bacteria-algae symbiotic system can significantly improve the sewage treatment capacity when treating sewage plant tailwater, and further enhance the photosynthesis and carbon fixation capacity of the microalgae.

Claims

1. A method for preparing a bacteria-algae symbiotic filler, characterized in that: Specifically, the process comprises adding an activated sludge dispersion to a reactor filled with filler, operating the reactor under aeration conditions for 7 to 10 days, and introducing simulated tail water during the operation; inoculating Chlorella vulgaris with the activated sludge dispersion and Chlorella vulgaris dispersion at a volume ratio of 1:5 to 50, operating the reactor at 22 to 30°C under light for 14 to 20 days, wherein the light-dark ratio is 6 to 12 hours of light and 12 to 18 hours of darkness; introducing simulated tail water during the operation, and obtaining a filler with a bacterial-algal symbiotic biofilm; The activated sludge is activated sludge that has been domesticated and cultured; the domestication and culture process of the activated sludge is as follows: the cleaned sludge is aerated for 24 hours under the conditions of pH 7.5-8.5 and water temperature 25-30°C, the sludge concentration is diluted to MLSS 100-500 mg / L, the activated sludge dispersion and the Chlorella dispersion are inoculated with the same initial concentration of Chlorella dispersion at a volume ratio of 1:1, simulated tail water is introduced for domestication, and aeration is continued for 3-7 days to obtain domesticated activated sludge.

2. The method for preparing the bacteria-algae symbiotic filler according to claim 1, characterized in that: Continue aeration for 3 to 7 days to maintain the dissolved oxygen concentration at 0.8 to 1.8 mg / L.

3. The method for preparing the bacteria-algae symbiotic filler according to claim 1, characterized in that: The filler is a hollow cylindrical MBBR filler.

4. The method for preparing the bacteria-algae symbiotic filler according to claim 1, wherein: The filling rate of the filler in the reactor is 30~50%.

5. The method for preparing the bacteria-algae symbiotic filler according to claim 1, characterized in that: The water inlet and outlet of the reactor are operated in a bottom-in and top-out mode.

6. The method for preparing the bacteria-algae symbiotic filler according to claim 5, characterized in that: A water distribution orifice plate is provided at the water inlet of the reactor.

7. The filler combination structure formed by the bacteria-algae symbiotic filler prepared by the preparation method of claim 1 is characterized by: The invention comprises a plurality of porous spherical shells filled with bacteria and algae symbiotic fillers, and the plurality of porous spherical shells are connected in series in any combination through connecting rods or connecting lines.

8. The packing combination structure according to claim 7, characterized in that: The filling rate of the biofilm filler in the porous spherical shell is 30% to 70%.

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