A membrane biofilm device for strengthening bacteria-algal heterogeneous stratification and a method for treating low carbon-nitrogen ratio wastewater

Abstract

The application relates to the technical field of sewage treatment, in particular to a membrane biofilm device for strengthening algal heterogeneity layering and a method for treating low-carbon-nitrogen-ratio wastewater. The membrane biofilm device comprises a liquid buffer bottle, a membrane biofilm mechanism and an aeration pump. The liquid buffer bottle is connected with the membrane biofilm mechanism through a water inlet pipe, and the aeration pump is connected with the membrane biofilm mechanism through an air inlet pipe. The membrane biofilm mechanism comprises a biofilm, a carrier film, an inner container and an LED lamp. The carrier film is wound on the inner container, and the LED is wound outside the membrane biofilm mechanism. Under the irradiation of the LED lamp, the biofilm is formed on the outer surface of the carrier film by a bacteria-algae symbiotic body. The problems of low nitrogen removal efficiency, high operation cost caused by additional carbon source and other limitations of the traditional low-carbon-nitrogen-ratio wastewater treatment process are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, and particularly relates to a membrane biofilm device for strengthening bacterial-algal heterogeneity layering and a method for treating low-carbon-nitrogen-ratio wastewater. BACKGROUND

[0002] With the continuous increase in population, the amount of wastewater produced by human production and life is increasing, and a large amount of pollutants are discharged into receiving water bodies, accelerating the deterioration of the water environment. In addition, the increase in nitrogen-containing substances in daily life and the use of agricultural fertilizers has led to an increasing concentration of nitrogen in wastewater, which presents a low carbon-nitrogen ratio. According to the traditional biological denitrification theory, sufficient organic carbon source is an essential condition for ensuring biological denitrification of wastewater. When the organic carbon source is insufficient, the denitrification process is hindered, and nitrogen-containing substances are not easily utilized by denitrifying bacteria, so the denitrification effect of traditional processes is not ideal.

[0003] Bacterial-algal symbiosis technology is a new wastewater treatment technology. Under light conditions, algae absorb CO2 released by bacterial respiration, convert pollutants into products and energy to meet their own growth needs in the light reaction, and release O2 into the environment. At the same time, bacteria in the water body carry out life activities under the promotion of O2, and then convert macromolecular substances into small molecular substances utilized by algae, and the two produce a physiological synergistic effect in the process of pollutant degradation. In addition, since the bacterial-algal symbiotic system contains photosynthetic autotrophic microorganisms-microalgae, it has the characteristics of high nitrogen utilization rate and low organic matter requirement, which can reduce the dependence on carbon source at the source for biological denitrification process, and is suitable for treating nitrogen-containing pollutants in wastewater with insufficient organic carbon source. It can be seen that the bacterial-algal symbiotic system has the advantages of low carbon demand, low energy consumption, low CO2 emission, and efficient removal of nitrogen elements. However, since microalgae cells exist in a suspended state in water, they are easy to flow out with the water flow, and microalgae belong to photoautotrophic organisms with a long generation cycle, which is at a disadvantage in competition with heterotrophic bacteria. The bacterial-algal symbiosis is difficult to maintain long-term stability, resulting in a decrease in treatment efficiency.

[0004] Membrane biofilm reactor technology takes bubbleless aeration as a prerequisite, gas in the membrane cavity is diffused from the inner wall of the membrane to the biofilm attached to its surface under the driving force of the pressure difference on both sides, and the liquid phase body is in direct contact with the biofilm, so compared with the traditional biofilm carrier, the core part carrier membrane plays a dual role of gas supply and microorganism attachment carrier. In addition, due to the heterogeneous mass transfer characteristics of pollutants and gas, it is easy to form a layered structure in the biofilm, so that many microorganisms with different habits and living environment can coexist in the membrane biofilm system, effectively improving the pollutant removal effect. It can be seen that the unique "double membrane" system of membrane biofilm technology not only provides a carrier for microorganism attachment, but also provides a possibility for slowing down the competition of algae in the same area by forming a functional bacterial population spatial layer on the inside of the biofilm. Therefore, using membrane biofilm technology to strengthen the heterogeneous layering and stable symbiosis of bacteria and algae, and treating low carbon-nitrogen ratio wastewater has certain development prospect and important research significance.

[0005] In view of the above defects, the inventor of the present application has finally obtained the present application after a long period of research and practice. SUMMARY

[0006] The purpose of the present application is to solve the problems of low nitrogen removal efficiency, high operating cost caused by additional carbon source and other limitations of traditional low carbon-nitrogen ratio wastewater treatment process, and to provide a membrane biofilm device for strengthening the heterogeneous layering of bacteria and algae and a method for treating low carbon-nitrogen ratio wastewater.

[0007] In order to achieve the above purpose, the present application discloses a membrane biofilm device for strengthening the heterogeneous layering of bacteria and algae, which comprises a liquid buffer bottle, a membrane biofilm mechanism and an aeration pump, the liquid buffer bottle is connected with the membrane biofilm mechanism through a water inlet pipe, the aeration pump is connected with the membrane biofilm mechanism through an air inlet pipe, the membrane biofilm mechanism comprises a biofilm, a carrier membrane, an inner container and an LED lamp, the carrier membrane is wound on the inner container, and the LED is wound outside the membrane biofilm mechanism.

[0008] The liquid buffer bottle is provided with a pH meter and a dissolved oxygen meter, and the liquid buffer bottle is connected with a water inlet valve and a water outlet valve.

[0009] A gas flow meter, a gas pressure gauge and a pressure control valve are arranged on the air inlet pipe of the air inlet pipe.

[0010] The inner container is arranged in a pool body, the pool body is connected with an air outlet pipe and a water outlet pipe, a pressure relief valve is arranged on the air outlet pipe, a peristaltic pump is arranged on the water outlet pipe, and the water outlet pipe is connected with the liquid buffer bottle.

[0011] The inner container is a hollow cavity, one end of the cavity is connected with the air inlet pipe, and the other end is connected with the air outlet pipe.

[0012] The inner container is connected by six hollow flat plates, the six flat plates are the same, the adjacent flat plates are communicated and the included angle is 43 degrees, and the two flat plates connected with each flat plate of the middle four flat plates are parallel to each other.

[0013] The application also discloses a method for treating low carbon-nitrogen ratio wastewater.

[0014] S1, the low carbon-nitrogen ratio wastewater enters the membrane biofilm mechanism from the liquid buffer bottle, flows from left to right, and the gas enters the membrane biofilm mechanism under the action of the aeration pump and flows from top to bottom;

[0015] S2, under the joint action of the LED lamp irradiation, the low carbon-nitrogen ratio wastewater in step S1 and the gas, the bacteria-algae symbiotic biofilm is grown on the carrier film by the bacteria-algae symbiotic body;

[0016] S3, the tail gas is released out of the reaction system under the action of the pressure relief valve.

[0017] The membrane biofilm mechanism should be subjected to film hanging and domestication culture of microorganisms in the reaction device before use, and the specific steps are as follows:

[0018] (1) inoculate sludge: inject the mixture of activated sludge and algal liquid into a beaker, add artificial wastewater, place the beaker in a magnetic stirrer for stirring, and irradiate the four sides and the top of the beaker, so that the surface radiation intensity of the beaker reaches 5000 lux, and 24h irradiation is carried out at the same time;

[0019] (2) initial film hanging: 2.5L of pre-cultured bacteria-algae sludge and artificial wastewater are added into the reactor, so that the mixed sludge concentration is 1500mg MLSS / L, the circulating pump speed and the magnetic stirrer speed are adjusted to 80rpm and 200rpm respectively, the circulating film hanging is carried out for 24h after each addition of nutrient solution, a total of 8 times of circulating film hanging are carried out, and in addition, the air inlet amount is set to 2.5L / min;

[0020] (3) strengthen film hanging: after the initial film hanging, the suspended sludge is discharged, and appropriate amount of bacteria-algae sludge and artificial wastewater are added again, so that the mixed sludge concentration is reduced to 1000mg MLSS / L, under the condition that the remaining conditions remain unchanged, batch water is added for 14 times, and the film hanging time of each time is set to 12h, in addition, the air inlet amount is set to 2.5L / min.

[0021] The beneficial effects of the present application compared with the prior art are as follows: the present application forms a bacteria-algae symbiotic biofilm on the outer surface of the carrier membrane through the bacteria-algae symbiotic body, in the biofilm, O2 is introduced into the membrane, and under the driving of the gas supply pressure, it enters the liquid phase. Due to the affinity of aerobic heterotrophic bacteria to oxygen and the tendency of algae to light source, the bacteria and algae are heterogeneously distributed on the surface of the fiber membrane wall, which slows down the competition of bacteria and algae in the same area, improves the growth efficiency of algae, strengthens the stability of bacteria-algae symbiosis, and further improves the pollutant removal efficiency. Due to the heterogeneous distribution of bacteria and algae and the oxygen production of algae photosynthesis, the biofilm formed on the surface of the fiber membrane forms an aerobic zone, an anaerobic zone and an anaerobic zone layer by layer along the radial direction of the membrane, so that the diverse functional bacteria groups formed inside the same biofilm are spatially layered, realizing the metabolic cooperation between autotrophic and heterotrophic microorganisms, enriching the biological phase, and at the same time making nitrogen complete the whole process removal in the same reactor, reducing the occupied area, and improving the pollutant removal efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0022] Fig. 1 Figure is a schematic diagram of the present application of a membrane biofilm device for strengthening bacteria-algae heterogeneous layering and a method for treating low carbon-nitrogen ratio wastewater;

[0023] Fig. 2 Figure is a schematic diagram of the present application of a membrane biofilm device for strengthening bacteria-algae heterogeneous layering and a method for treating low carbon-nitrogen ratio wastewater;

[0024] Fig. 3 Figure is a specific schematic diagram of the present application of a membrane biofilm device for strengthening bacteria-algae heterogeneous layering and a method for treating low carbon-nitrogen ratio wastewater (1);

[0025] Fig. 4 Figure is a specific schematic diagram of the present application of a membrane biofilm device for strengthening bacteria-algae heterogeneous layering and a method for treating low carbon-nitrogen ratio wastewater (2).

[0026] Figures in the drawings represent:

[0027] 1-liquid buffer bottle; 2-pH meter; 3-dissolved oxygen meter; 4-water inlet valve; 5-water outlet valve; 6-peristaltic pump; 7-membrane biofilm mechanism; 8-biofilm; 9-carrier membrane; 10-LED lamp; 11-gas flow meter; 12-gas pressure gauge; 13-pressure control valve; 14-aeration pump; 15-pressure relief valve; 16-gas inlet pipe; 17-gas outlet pipe; 18-water inlet pipe; 19-water outlet pipe. DETAILED DESCRIPTION

[0028] The above and other technical features and advantages of the present application will be described in more detail below with reference to the accompanying drawings.

[0029] Example 1

[0030] The embodiment is composed of a liquid buffer bottle 1, a pH meter 2, a dissolved oxygen meter 3, a water inlet valve 4, a water outlet valve 5, a peristaltic pump 6, a membrane biofilm mechanism 7, a biofilm 8, a carrier membrane 9, an LED lamp 10, a gas flow meter 11, a barometer 12, a pressure control valve 13, an aeration pump 14, a pressure relief valve 15, an air inlet pipe 16, an air outlet pipe 17, a water inlet pipe 18, and a water outlet pipe 19.

[0031] Firstly, the low carbon-nitrogen ratio wastewater enters the membrane biofilm mechanism 7 from the liquid buffer bottle 1 under the action of the water inlet valve 4 and flows from left to right; the gas is generated by the aeration pump 14 and enters the inner cavity of the carrier membrane 9 from the top of the membrane biofilm mechanism under the action of the gas flow meter 11, the barometer 12, the pressure control valve 13, and the aeration pump 14 and flows from top to bottom; and the bacteria-algae symbiotic biofilm 8 grows on the carrier membrane 9 under the irradiation of the LED lamp 10 wound outside the membrane biofilm mechanism 7; the tail gas is released out of the reaction system under the action of the pressure relief valve 15; and the water body entering the membrane biofilm mechanism is removed of the pollutants such as nitrogen under the joint action of the bacteria-algae symbiotic body in the suspended state and the bacteria-algae biofilm 8. The water body is circulated under the joint action of the liquid buffer bottle 1 and the peristaltic pump 6, and after a hydraulic retention time, the water body is discharged to the outside of the reaction system at a certain flow rate through the water outlet pipe 19 under the action of the water outlet valve 5. At the same time, the dissolved oxygen in the bacteria-algae symbiotic membrane biofilm system is continuously monitored by the dissolved oxygen meter 3, and the pH value is monitored by the pH meter 2.

[0032] The membrane biofilm mechanism is composed of a transparent acrylic pool body, a biofilm 8, a carrier membrane 9, an LED lamp 10, and an inner container 20. The carrier membrane 9 is wound on the upper part of the device inner container 20, so that the water flow is perpendicular to the carrier membrane 9, so that the water flow passes through the membrane surface in a cross-flow form and strengthens the convection transfer of the pollutants on the membrane surface. As for the flow state, due to the influence of the water inlet and outlet system and the circulation system, the water flow is between the complete mixing state and the plug flow state, so the water quality is completely consistent at each place in the reaction device. The low carbon-nitrogen ratio wastewater enters from the side of the membrane biofilm mechanism 7, the water flow rate and flow are controlled by the peristaltic pump 6, and the water flows from the left side to the right side; O2 enters the inner cavity of the membrane assembly from top to bottom in a certain proportion under the action of the gas flow meter 11, the barometer 12, the pressure control valve 13, and the aeration pump 14; the tail gas is discharged from above the carrier membrane 9 under the action of the pressure relief valve 15; and the LED lamp 10 is wound outside the membrane biofilm mechanism 7 to facilitate the formation of the biofilm 8. The membrane biofilm mechanism 7 should be acclimated and cultured with microorganisms in the reaction device before use: the microorganisms in the reaction device are acclimated and cultured by gradually adding low carbon-nitrogen ratio wastewater, and the water quality is monitored at the same time.

[0033] The bacteria-algae symbiotic body forms a bacteria-algae symbiotic biofilm 8 on the outer surface of the carrier membrane 9, and the carrier membrane 9 is wound on the inner container 20. The carrier membrane 9 is attached to the inner container in two ways, namely spiral winding and adhesion. Spiral winding: the carrier membrane is a hollow fiber membrane, and O2 is input from the top end of the carrier membrane and output from the bottom end. Adhesion: the inner container 20 is fixed in the membrane biofilm mechanism 7, the inner container 20 is a hollow cavity, the right end of the cavity is connected to the air inlet pipe 16, and the left end of the cavity is connected to the air outlet pipe 17, the inner container 20 is connected by six hollow plates, the six plates are the same, the adjacent plates are connected and the angle between them is 43°, and the two plates connected to each of the four middle plates are parallel to each other. In the biofilm 8, O2 is introduced into the membrane, and under the driving force of the gas supply pressure, it enters the liquid phase. Due to the affinity of aerobic heterotrophic bacteria for oxygen and the tendency of algae to light, bacteria and algae are heterogeneously distributed on the surface of the fiber membrane wall, reducing competition between bacteria and algae in the same area, improving the growth efficiency of algae, strengthening the stability of bacteria-algae symbiosis, and thus improving the efficiency of pollutant removal; due to the heterogeneous distribution of bacteria and algae and the photosynthetic oxygen production of algae, the biofilm formed on the surface of the fiber membrane forms an aerobic zone, an anaerobic zone, and an anaerobic zone layer by layer along the radial direction of the membrane, so that the diversity of the functional bacteria group formed inside the same biofilm is spatially layered, realizing the metabolic cooperation between autotrophic and heterotrophic microorganisms, enriching the biological phase, and at the same time completing the whole process of nitrogen removal in the same reactor, reducing the occupied area, and improving the efficiency of pollutant removal.

[0034] Example 2

[0035] The membrane biofilm mechanism 7 should be subjected to biofilm formation and domestication culture of microorganisms in the reaction device before use. The biofilm formation is divided into seeding sludge, primary biofilm formation and strengthened biofilm formation, and the specific process is as follows:

[0036] (1) Seeding sludge

[0037] A certain amount of activated sludge and algae liquid mixture is injected into a 5L beaker, and an appropriate amount of artificial wastewater is added. The beaker is placed in a magnetic stirrer for slow stirring. Light is provided around the beaker and at the top, so that the surface of the beaker has a radiation intensity of about 5000 lux, and 24h light is provided at the same time.

[0038] (2) Primary biofilm formation

[0039] 2.5L of pre-cultured bacteria-algae sludge and artificial wastewater are added to the reactor, so that the mixed sludge concentration is 1500mgMLSS / L. The circulating pump speed and the magnetic stirrer speed are adjusted to 80rpm and 200rpm respectively. After each addition of nutrient solution, the biofilm is circulated for 24h, and a total of 8 cycles of biofilm circulation are performed. In addition, the air inlet amount is set to 2.5L / min.

[0040] (3) Strengthened biofilm formation

[0041] After the initial biofilm formation, the suspended sludge was discharged, and an appropriate amount of bacterial and algal sludge and artificial wastewater was added again to reduce the mixed sludge concentration to 1000 mg MLSS / L. Under the condition that the remaining conditions remain unchanged, the influent was added in 14 batches, and the biofilm formation time of each batch was set to 12 h. In addition, the air inlet amount was set to 2.5 L / min.

[0042] In this embodiment, the microorganisms in the reaction device are domesticated and cultured by gradually adding low carbon-nitrogen ratio wastewater, and the water quality is monitored. The low carbon-nitrogen ratio wastewater is mixed with nitrogen-free wastewater, and the mixture is used as influent. The domestication and culture process is divided into three stages, specifically: in the first stage, the proportion of nitrogen content in the influent water body is adjusted to 1%; in the second stage, the proportion of nitrogen content in the influent is gradually increased until the proportion of nitrogen content in the water body is 3%; in the third stage, the proportion of nitrogen content in the influent water body is adjusted to 6-7%.

[0043] Low carbon-nitrogen ratio wastewater is used as influent, and the water temperature is maintained at 25-30°C throughout the operation. The experimental results obtained by monitoring are as follows: the COD removal rate can reach 91±3.8%, and the total nitrogen removal rate can reach 87±3.8%, which is 17-27% higher than the removal efficiency of the traditional activated sludge method.

[0044] Example 3

[0045] According to Figs. 1 to 4 The present embodiment can be described as follows: the difference between this embodiment and Example 1 is the installation method of the carrier membrane 9. That is, the inner container 20 is fixed in the reactor 7, the inner container 20 is a hollow cavity, the right end of the cavity is connected to the air inlet pipe 16, the left end of the cavity is connected to the air outlet pipe 17, the inner container 20 is connected by six hollow plates, the six plates are the same, the adjacent plates are connected and the included angle is 43°, and the two plates connected to each of the four middle plates are parallel to each other. The remaining components and connection methods are the same as those of Example 1.

[0046] Low carbon-nitrogen ratio wastewater is used as influent, and the water temperature is maintained at 25-30°C throughout the operation. The experimental results obtained by monitoring are as follows: the COD removal rate can reach 90±8.5%, and the total nitrogen removal rate can reach 87±4.3%, which is 17-27% higher than the removal efficiency of the traditional activated sludge method.

[0047] Example 4

[0048] Two groups of reactors that are exactly the same are built, one of which adds algae and activated sludge, serving as a membrane aeration bacterial and algal biofilm reactor (bacterial and algal MABR), and the other adds an equal amount of activated sludge, serving as a membrane aeration biofilm reactor (MABR).

[0049] (1) Biomass

[0050] The biomass of the MABR was 4.9 ± 0.7 mg / cm³ on days 10, 20, and 30 of operation. 2 7.7±0.5mg / cm 2 8.6±0.6mg / cm 2 The biomass of the bacterial-algae MABR was 7.4 ± 0.2 mg / cm³ on days 10, 20, and 30 of operation. 2 9.9±0.6mg / cm 2 11.9±0.8mg / cm 2 .

[0051] (2) Biofilm thickness

[0052] The biofilm thickness measurements on the sides and top of the carrier in the MABR were approximately 1300–1600 μm and 800–1200 μm, respectively; while the biofilm thickness measurements on the sides and top of the carrier in the bacterial-algal MABR were approximately 2000 μm and 1500–1800 μm, respectively.

[0053] (3) Scanning electron microscopy analysis

[0054] Compared to bacterial and algal biofilms, bacterial cells in activated sludge biofilms are more tightly bound together, resulting in a denser biofilm structure, while bacterial and algal biofilms are more "loose".

[0055] In summary, comparing the biofilm formation effects of the two systems on days 10, 20, and 30 of operation, the biomass of the bacterial-algal MABR was approximately 1.3–1.5 times that of the MABR, and the biofilm thickness was approximately 1.2–1.6 times that of the MABR. This indicates that under the same operating conditions, the bacterial-algal biofilm exhibits higher activity compared to the activated sludge biofilm. Scanning electron microscopy analysis revealed that the bacterial and algal cells in the bacterial-algal biofilm are tightly connected, forming a more porous structure, which is beneficial for substrate mass transfer.

[0056] Example 5

[0057] The operation process is divided into three stages based on the aeration rate. The first stage (0-75 days) has an aeration rate of 2.5 L / min; the second stage (76-115 days) has an aeration rate of 0 L / min during the day and 2.5 L / min at night; and the third stage (116-160 days) has an aeration rate of 2 L / min.

[0058] The experimental data obtained from the monitoring show that, under the conditions of an aeration rate of 2.5 L / min throughout the day, no aeration during the day, and aeration of 2.5 L / min at night, and 2 L / min throughout the day, the reactor has a good removal effect on COD and total nitrogen during the stable operation period, with a removal rate of over 85%.

[0059] The above descriptions are only the preferable embodiments of the present application, which are only illustrative but not restrictive. It is understood by those skilled in the art that many changes, modifications, even equivalences can be made to the present application within the spirit and scope defined by the claims of the present application, and all of them will fall into the protection scope of the present application.

Claims

1. A membrane biofilm device for enhancing heterogeneous stratification of bacteria and algae, characterized in that, The device comprises a liquid buffer bottle, a membrane biofilm mechanism, and an aeration pump, the liquid buffer bottle is connected with the membrane biofilm mechanism through a water inlet pipe, the aeration pump is connected with the membrane biofilm mechanism through an air inlet pipe, the membrane biofilm mechanism comprises a biofilm, a carrier film, an inner container, and an LED lamp, the carrier film is wound on the inner container, and the LED is wound outside the membrane biofilm mechanism; under the irradiation of the LED lamp, the biofilm is formed on the outer surface of the carrier film by the bacterial-algal symbiont. The inner container is composed of six hollow flat plates connected end to end, the six flat plates are the same, the inner parts of adjacent flat plates are communicated and the included angle is 43°, and the two flat plates connected with each flat plate among the four middle flat plates are parallel to each other.

2. The enhanced bacteria-algae heterogeneously layered membrane biofilm apparatus of claim 1, wherein, The liquid buffer bottle is provided with a pH meter and a dissolved oxygen meter, and is connected with a water inlet valve and a water outlet valve.

3. The enhanced bacteria-algae heterogeneously layered membrane biofilm apparatus of claim 1, wherein, The air inlet pipe is provided with a gas flow meter, a gas pressure gauge, and a pressure control valve on the air inlet pipeline.

4. The enhanced bacteria-algal heterogenous layered biofilm apparatus of claim 1, wherein, The inner container is arranged in a pool body, the pool body is connected with an air outlet pipe and a water outlet pipe, the air outlet pipe is provided with a pressure relief valve, the water outlet pipe is provided with a peristaltic pump, and the water outlet pipe is connected with the liquid buffer bottle.

5. The enhanced bacteria-algae heterogeneously layered membrane biofilm apparatus of claim 1, wherein, The inner container is a hollow cavity, one end of the cavity is connected with the air inlet pipe, and the other end is connected with the air outlet pipe.

6. A method of treating low carbon to nitrogen ratio wastewater, characterized by, The device is applied to the membrane biofilm device for strengthening bacterial-algal heterogeneous stratification, and comprises the following steps: S1, low carbon-nitrogen ratio wastewater flows from left to right in the membrane biofilm mechanism, and gas flows from top to bottom in the membrane biofilm mechanism under the action of the aeration pump; S2, under the irradiation of the LED lamp and the joint action of the low carbon-nitrogen ratio wastewater and the gas in step S1, the bacterial-algal symbiotic biofilm is grown on the carrier film by the bacterial-algal symbiont; S3, tail gas is released out of the reaction system under the action of the pressure relief valve; Before use, the membrane biofilm mechanism should be subjected to biofilm formation and domestication culture of microorganisms in the reaction device, and the specific steps are as follows: (1) inoculate sludge: inject the mixture of activated sludge and algal liquid into a beaker, add artificial wastewater, place the beaker in a magnetic stirrer for stirring, and irradiate the four sides and the top of the beaker, so that the surface radiation intensity of the beaker reaches 5000 lux, and at the same time, 24 h irradiation is performed; (2) initial biofilm formation: add 2.5 L of pre-cultured bacterial-algal sludge and artificial wastewater into the reactor, so that the mixed sludge concentration is 1500 mg MLSS / L, the circulating pump speed and the magnetic stirrer speed are adjusted to 80 rpm and 200 rpm respectively, the circulating biofilm formation is performed for 24 h after adding the nutrient solution each time, a total of 8 times of circulating biofilm formation are performed, and in addition, the air inlet amount is set to 2.5 L / min; (3) strengthening biofilm formation: after the initial biofilm formation, the suspended sludge is discharged, and appropriate amount of bacterial-algal sludge and artificial wastewater is added again, so that the mixed sludge concentration is reduced to 1000 mg MLSS / L, under the condition that the remaining conditions remain unchanged, batch water is added for 14 times, and the biofilm formation time is set to 12 h each time, and in addition, the air inlet amount is set to 2.5 L / min.

Images