Bacteria-algae particle preparation method and system for promoting granulation of bacterial-algae system based on pressure response

Abstract

The invention belongs to the technical field of biological sewage treatment, and relates to a bacteria-algae particle preparation method and system for promoting bacteria-algae system granulation based on pressure response. The preparation method comprises the following steps: co-culturing the mixed microalgae cultured to a logarithmic phase and aerobic activated sludge in a photobioreactor, in the culture process, jointly regulating and controlling aeration, a carbon source and inlet and outlet water to promote granulation of a bacteria-algae system according to the principle of'pressure-induced stress response ', and controlling dissolved oxygen levels in different periods according to the principle of'unbalanced air supply' during aeration regulation and control; the carbon source regulation follows the principle of unbalanced nutrition to control the COD concentration in different time periods; the water inlet and outlet regulation follows the principle of reducing the settling time, and the water change settling time is gradually shortened in the culture period. The bacteria-algae granular sludge which is good in settling performance, high in dirt-removing power and compact in structure is prepared, the prepared bacteria-algae granular sludge is used for treating sewage and wastewater, pollution of carbon, nitrogen, phosphorus and the like can be efficiently solved, the effluent quality is effectively improved, and carbon emission reduction in the sewage treatment field is promoted.

Description

Technical Field

[0001] The present invention belongs to the technical field of biological sewage treatment. Specifically, it relates to a method and system for preparing algal-bacterial particles based on pressure response to promote granulation of algal-bacterial systems. Background Art

[0002] The algal-bacterial symbiosis technology is a biological treatment technology that combines the powerful uptake function of algae for nutrients and organic matter with the efficient degradation ability of bacteria for pollutants to achieve the purpose of sewage purification. It has received increasing attention due to its low energy demand, low-cost investment, and potential resource recovery. "Pollutants" are the energy sources for bacteria and algae, and the application of the algal-bacterial process can truly achieve "turning waste into treasure". There are mainly three forms of the algal-bacterial symbiotic system, namely algal-bacterial biofilm, suspended algal-bacteria, and algal-bacterial particles. Among them, the algal-bacterial particle technology has attracted much attention due to its outstanding advantages such as high organic load, land saving, and low-cost algae recovery.

[0003] Although the algal-bacterial particle technology shows great potential in wastewater treatment, rapid granulation of algal-bacteria has always been one of the challenges in the engineering application of this technology. Currently, the most common methods for preparing algal-bacterial particles include inoculating aerobic granular sludge method, SBR cultivation method, carrier immobilization method, high shear force method, air-lift method, etc. The algal-bacterial particles prepared by mixing microalgae with ready-made granular sludge have a short granulation period, but there are problems such as limited sources of granular sludge and weak binding between algae and bacteria. The traditional SBR method uses flocculent sludge and microalgae for granulation and makes it granulate by regulating operating parameters. This method has a long granulation period and unstable granulation effect. The carrier immobilization method uses specific carrier materials (such as polyurethane foam, fiber materials, ceramic particles, etc.) as the attachment points for microorganisms and algae, and makes them grow on the carrier and form particles. The carrier cost is high and aging requires regular replacement. The high shear force method and the air-lift method promote particle formation through external forces such as mechanical stirring and aeration, and are often used in combination with other granulation methods to reduce energy consumption costs. Summary of the Invention

[0005] The object of the present invention is to overcome the deficiencies of the existing algal-bacterial granulation technology, and use the extracellular polymer secreted by algal-bacterial pressure response as the core means of regulation to provide a method and system for preparing algal-bacterial particles that are fast, economical, and reproducible.

[0006] The technical solution adopted by the present invention to solve this problem is:

[0007] A method for preparing algal-bacterial particles based on pressure response to promote granulation of algal-bacterial systems. The preparation method is to co-culture mixed microalgae cultured to the logarithmic growth phase and aerobic activated sludge in a photobioreactor, and follow the principle of "pressure-induced stress response" to jointly regulate aeration, carbon source, influent and effluent during the cultivation process to promote granulation of the algal-bacterial system, where:

[0008] The aeration regulation follows the principle of "unbalanced air supply" to control the dissolved oxygen level at different times;

[0009] The carbon source regulation follows the principle of "unbalanced nutrition" to control the COD concentration at different times;

[0010] The influent and effluent regulation follows the principle of "gradually reducing sedimentation time", and gradually shortens the water change sedimentation time during the cultivation period.

[0011] In the above technical solution, the mixed microalgae belong to Chlorophyta, preferably Tetradesmus obliquus, Chlorella vulgaris, and filamentous algae.

[0012] In the above technical solution, the conditions for culturing pure microalgae are preferably: temperature: 15 - 30 °C, pH: 6.5 - 7.5, light intensity: 2000 - 4000 Lux, light / dark ratio 0.8 - 1.5. Preferably, the mixed microalgae cultured for 4 - 15 days are used for granulation.

[0013] In the above technical solution, the aerobic activated sludge passes through a 20 - 80 mesh sieve, and preferably, the sludge concentration in the photobioreactor is controlled at 2.0 - 4.0 g / L.

[0014] In the above technical solution, in the aeration regulation, the principle of "unbalanced air supply" is: in the first 60 - 80% of the water change cycle, the dissolved oxygen is controlled at 2.0 - 4.0 mg / L, and in the last 20% - 40% of the water change cycle, the dissolved oxygen is controlled at 1.0 - 3.0 mg / L.

[0015] In the above technical solution, in the aeration regulation, nitrogen is used as the auxiliary gas source for shear stress, and the nitrogen flow rate is adjusted to control the hydrodynamic shear stress at 1.0×10 -2 -5.0×10 -2 N / m 2 。

[0016] In the above technical solution, in the carbon source regulation, the principle of "unbalanced nutrition" is: in the first 20 - 60% of the water change cycle, the COD concentration is controlled not less than 50 mg / L, and in the last 40% - 80% of the water change cycle, the COD concentration is controlled not higher than 50 mg / L.

[0017] In the above technical solution, in the influent and effluent regulation, the principle of "gradually reducing sedimentation time" is: the sedimentation time is 3 - 30 min, and the water change sedimentation time is gradually shortened during the cultivation period.

[0018] The second object of the present invention is to provide a photobioreactor system for preparing bacteria - algae particles, the system includes a photobioreactor, a lighting unit, a chemical dosing unit, an aeration regulation unit, and an influent and effluent control unit, and the system further includes a carbon source control unit connected to the chemical dosing unit.

[0019] In the above technical solution, the height / diameter ratio of the photobioreactor is not less than 2, and the operating conditions of the photobioreactor include: the temperature is 10 - 40 °C, the hydraulic retention time is 6 - 12 h, intermittent water inlet and outlet, and one hydraulic retention time is one water change cycle.

[0020] In the above technical solution, the lighting unit is composed of an internal waterproof LED light strip, a light intensity regulator, and a lighting duration controller. Preferably, the light / dark ratio is controlled to be 1 - 5.

[0021] In the above technical solution, the chemical dosing unit supplies substances necessary for the growth of the bacteria - algae system, and the chemicals added by the chemical dosing unit include sodium acetate, ammonium chloride, potassium dihydrogen phosphate, and trace elements.

[0022] In the above technical solution, the photobioreactor adopts an air - lift photobioreactor, which includes a reactor main tank, a central cylinder arranged along the central axis of the reactor main tank, a waterproof LED light strip spirally wound around the central cylinder, an air inlet pipe inserted inside the central cylinder, and sampling ports arranged at intervals along the height direction of the reactor main tank.

[0023] In the above technical solution, the air inlet pipe is inserted into the reactor main tank from the bottom of the reactor main tank, an exhaust valve is arranged at the top of the reactor main tank, the air inlet end of the air inlet pipe is connected to an air pump, and an air inlet valve is arranged on the air inlet pipe.

[0024] In the above technical solution, an overflow weir is arranged at the top of the central cylinder, and a baffle is arranged above it.

[0025] In the above technical solution, a light - strip power connection port is also arranged at the top of the reactor main tank.

[0026] In the above technical solution, the aeration regulation follows the principle of "uneven air supply" to control the dissolved oxygen level at different times. Preferably, in the first 60 - 80% of the water change cycle, the dissolved oxygen is controlled to be 2.0 - 4.0 mg / L, and in the last 20% - 40% of the water change cycle, the dissolved oxygen is controlled to be 1.0 - 3.0 mg / L.

[0027] In the above technical solution, the principle of "uneven air supply" also includes using nitrogen as an auxiliary gas source for shear stress. Preferably, the nitrogen flow rate is adjusted to control the hydrodynamic shear stress to be 1.0×10 -2 -5.0×10 -2 N / m 2 。

[0028] In the above technical solution, the carbon source regulation follows the principle of "unbalanced nutrition" to control the COD concentration at different times. Preferably, in the first 20%-60% of the water change cycle, the COD concentration is controlled not to be lower than 50 mg / L, and in the last 40%-80% of the water change cycle, the COD concentration is controlled not to be higher than 50 mg / L.

[0029] In the above technical solution, the influent and effluent regulation follows the principle of "gradually reducing sedimentation time", and the water change sedimentation time is gradually shortened during the cultivation cycle. The sedimentation time is preferably 3-30 min.

[0030] The advantages and positive effects of the present invention are as follows: The present invention prepares algal-bacterial granular sludge with good sedimentation performance, strong decontamination ability and compact structure. Using the prepared algal-bacterial granular sludge to treat sewage and wastewater can efficiently solve the pollution of carbon, nitrogen, phosphorus, etc., effectively improve the effluent quality, and contribute to carbon emission reduction in the field of sewage treatment. In particular, the principle of "pressure-induced stress response" provided by the present invention has a wide range of adaptability and can be effectively used for activated sludge and mixed microalgae from different sources. EPS secreted by bacteria and microalgae under the stress conditions of unbalanced aeration and nutrition is an important medium to promote granulation. The present invention focuses on using the principle of "pressure-induced stress response" to promote the directional regulation of the granulation process by EPS secretion, and at the same time, by adjusting the shear stress and the influent and effluent selection pressure, algal-bacterial granules with a compact structure and a large particle size range are screened.

[0031] In addition, as the creative auxiliary evidence of the present invention, it is also reflected in the following important aspects:

[0032] 1. The algal-bacterial granular sludge preparation technology of the present invention has significant economic, environmental and social benefits after transformation, specifically including: By improving the granulation process, the sludge sedimentation performance and treatment efficiency are greatly improved, the energy consumption and the use of chemical agents in traditional sewage treatment are reduced, thereby reducing the operating cost; Nitrogen, phosphorus and organic pollutants are efficiently removed, and at the same time, carbon is fixed by the photosynthesis of algae, reducing greenhouse gas emissions; The produced algal-bacterial granular sludge is reused as a resource, such as being converted into organic fertilizers, biofuels or other value-added products, to build a circular economy model; It is applicable to the treatment of municipal sewage, industrial wastewater and agricultural wastewater, meeting the global sewage treatment market's demand for efficient and green technologies.

[0033] 2. At present, the research in the field of algal-bacterial combined treatment technology at home and abroad mostly focuses on the laboratory scale, and there is still a lack of stable and replicable granular sludge preparation technology. The present invention fills the following technical gaps: A method for efficiently inducing algal-bacterial symbiotic granulation is proposed, enabling the algal-bacterial granular sludge to have excellent sedimentation and stability; The algal-bacterial ratio and cultivation conditions are optimized to make the granular sludge adapt to different sewage treatment scenarios.

[0034] 3. The technical solution of the present invention solves the problems that microalgae have difficulty growing in high-solid-content sludge, and the granular sludge in the traditional granulation process is prone to disintegration and has a long cultivation period.

[0035] Other features and advantages of the present invention will be described in detail in the following specific implementation section. Brief Description of the Drawings

[0036] The following will further describe the technical solution of the present invention in detail in conjunction with the drawings and embodiments. However, it should be noted that these drawings are only designed for explanatory purposes and therefore do not limit the scope of the present invention. In addition, unless otherwise specified, these drawings are only intended to conceptually illustrate the structural configurations described herein and are not necessarily drawn to scale.

[0037] Figure 1 is a schematic diagram of an SBR reactor;

[0038] Figure 2 is a schematic diagram of an air-lift photobioreactor;

[0039] Figure 3 is a scanning electron micrograph of the bacterial-algal granular sludge.

[0040] In the figure: 1 - exhaust valve, 2 - reactor main tank, 3 - lamp belt power connection port, 4 - baffle, 5 - overflow weir, 6 - central cylinder, 7 - lamp belt, 8 - sampling port, 9 - sampling port, 10 - intake valve, 11 - intake pipe, 12 - air pump. Detailed Description of the Preferred Embodiments

[0041] First of all, it should be noted that the following will specifically illustrate the specific structure, characteristics, advantages, etc. of the present invention by way of examples. However, all descriptions are only for the purpose of explanation and should not be construed as forming any limitation to the present invention. In addition, any single technical feature described or implied in each of the embodiments mentioned herein, or any single technical feature shown or implied in each of the drawings, can still be arbitrarily combined or deleted between these technical features (or their equivalents) to obtain more other embodiments of the present invention that may not be directly mentioned herein. Additionally, for the sake of simplifying the drawings, the same or similar technical features may only be marked in one place in the same drawing.

[0042] In the present invention, unless otherwise clearly specified and defined, terms such as "installation", "setting", "connection", "fixation", "swivel connection" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral body; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components or the interaction relationship between two components. Unless otherwise clearly defined, for those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] The following will detail the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not used to limit the present invention.

[0044] Example 1

[0045] The present invention provides a method for preparing algal-bacterial granules, which includes co-culturing mixed microalgae cultured to the logarithmic growth phase and aerobic activated sludge in a photobioreactor. During the culture process, the "pressure-induced stress response" principle is followed to jointly regulate aeration, carbon source, influent and effluent to promote granulation in the system, where:

[0046] The aeration regulation follows the "uneven air supply" principle to control the dissolved oxygen level at different times;

[0047] The carbon source regulation follows the "uneven nutrition" principle to control the COD concentration at different times;

[0048] The influent and effluent regulation follows the "gradually shrinking sedimentation time" principle, and gradually shortens the water change and sedimentation time during the culture cycle.

[0049] The present invention applies the "pressure-induced stress response" principle to promote EPS secretion and directionally regulate the granulation process. At the same time, by adjusting the shear stress and the influent and effluent selection pressure, algal-bacterial granules with a compact structure and a large particle size range are screened.

[0050] In the present invention, the mixed microalgae used belong to Chlorophyta, preferably Scenedesmus obliquus, Chlorella vulgaris, and filamentous algae. Further, the preferred conditions for culturing pure microalgae are: temperature: 15 - 30 °C, pH: 6.5 - 7.5, light intensity: 2000 - 4000 Lux, light / dark ratio 0.8 - 1.5. Preferably, the mixed microalgae cultured for 4 - 15 days are used for granulation.

[0051] In the present invention, the aerobic activated sludge is passed through a 20 - 80 mesh sieve before use. Preferably, the sludge concentration in the photobioreactor is controlled at 2.0 - 4.0 g / L.

[0052] In the present invention, the aeration regulation follows the principle of "uneven air supply" to control the dissolved oxygen level at different times. Preferably, in the first 60 - 80% of the water change cycle, the dissolved oxygen is controlled at 2.0 - 4.0 mg / L, and in the last 20% - 40% of the water change cycle, the dissolved oxygen is controlled at 1.0 - 3.0 mg / L.

[0053] In the present invention, the principle of "uneven air supply" also includes using nitrogen as an auxiliary gas source for shear stress. Preferably, the hydrodynamic shear stress is controlled at 1.0×10 -2 -5.0×10 -2 N / m 2 .

[0054] In the present invention, the carbon source regulation follows the principle of "uneven nutrition" to control the COD concentration at different times. Preferably, in the first 20 - 60% of the water change cycle, the COD concentration is controlled not less than 50 mg / L, and in the last 40% - 80% of the water change cycle, the COD concentration is controlled not higher than 50 mg / L.

[0055] In the present invention, the influent and effluent regulation follows the principle of "selection pressure screening", and the water change and sedimentation time is gradually shortened during the cultivation cycle. The sedimentation time is preferably 3 - 30 min.

[0056] Example 2

[0057] The present invention provides a photobioreactor system for preparing algal - bacterial particles, which includes a photobioreactor, a lighting unit, a chemical dosing unit, an aeration regulation unit, an influent and effluent control unit. The system also includes a carbon source control unit connected to the chemical dosing unit. Preferably, the height - to - diameter ratio of the photobioreactor is not less than 2.

[0058] In the present invention, the photobioreactor adopts an air - lift photobioreactor, which includes a reactor main tank 2, a central cylinder 6 arranged along the central axis of the reactor main tank 2, a waterproof LED light strip 7 spirally wound around the central cylinder 6, an air inlet pipe 11 inserted inside the central cylinder 6, and sampling ports 8 arranged at intervals along the height direction of the reactor main tank 2.

[0059] In the present invention, the air inlet pipe 11 is inserted into the reactor main tank 2 from the bottom of the reactor main tank 2. An exhaust valve 1 is arranged at the top of the reactor main tank 2. The air inlet end of the air inlet pipe 11 is connected to an air pump 12, and an air inlet valve 10 is arranged on the air inlet pipe 11. Aeration is carried out in the photobioreactor in an air - lift manner, which helps to make the air contact more fully with the mixed microalgae and aerobic activated sludge.

[0060] In the present invention, an overflow weir 5 is arranged at the top of the central cylinder 6, and a baffle 4 is arranged above it.

[0061] In the present invention, a lamp belt power connection port 3 is further provided at the top of the reactor main tank 2.

[0062] In the present invention, the operating conditions of the photobioreactor include: the temperature is 10 - 40 °C, the hydraulic retention time is 6 - 12 h, intermittent influent and effluent, and one hydraulic retention time is one water change cycle.

[0063] In the present invention, the lighting unit is composed of an in-built waterproof LED lamp belt, a light intensity regulator, and a lighting duration controller. Preferably, the light / dark ratio is controlled to be 1 - 5.

[0064] In the present invention, the aeration regulation follows the principle of "uneven air supply" to control the dissolved oxygen level at different times. Preferably, in the first 60 - 80% of the water change cycle, the dissolved oxygen is controlled to be 2.0 - 4.0 mg / L, and in the last 20% - 40% of the water change cycle, the dissolved oxygen is controlled to be 1.0 - 3.0 mg / L.

[0065] In the present invention, the principle of "uneven air supply" also includes using nitrogen as an auxiliary gas source for shear stress. Preferably, the hydrodynamic shear stress is controlled to be 1.0×10 -2 -5.0×10 -2 N / m 2 .

[0066] In the present invention, the chemical dosing unit supplies the necessary substances for the growth of the bacteria - algae system. Preferably, the chemical composition includes sodium acetate, ammonium chloride, potassium dihydrogen phosphate, and trace elements. Further, the carbon source regulation follows the principle of "uneven nutrition" to control the COD concentration at different times. Preferably, in the first 20 - 60% of the water change cycle, the COD concentration is controlled not to be lower than 50 mg / L, and in the last 40% - 80% of the water change cycle, the COD concentration is controlled not to be higher than 50 mg / L.

[0067] In the present invention, the influent - effluent regulation follows the principle of "selection pressure screening", and the water change and sedimentation time is gradually shortened during the cultivation period. The sedimentation time is preferably 3 - 30 min.

[0068] Application Example

[0069] The technical solution of the present invention will be further elaborated in detail below in conjunction with the embodiments. In the following application examples, the COD, TN, and TP contents are measured by the Hach - spectrophotometry method; the ammonia nitrogen content is measured by the Nessler's reagent spectrophotometry method.

[0070] Application Example 1 Cultivation of Bacteria - Algae Particles in a Photobioreactor

[0071] The return sludge from the secondary sedimentation tank of a municipal wastewater treatment plant in Shanghai is passed through a 20 - mesh sieve and placed in a sequencing batch reactor ( Figure 1 ) for 3 days to restore the sludge activity. AsFigure 1 As shown in Figure 1 , the sequencing batch reactor includes the main tank of the SBR reactor, a stirring paddle motor, a stirring paddle, stirring blades, an aeration control unit, and sampling ports arranged at intervals along the direction of the main tank of the SBR reactor. The aeration control unit includes an air pump, an air pipe, and an aeration head. The operating conditions of the sequencing batch reactor are as follows: the volume is 10 L, the hydraulic retention time (HRT) is 8 hours, the sludge retention time (SRT) is 20 days, and the temperature and dissolved oxygen (DO) levels are controlled at 20.0 ± 0.5 °C and 2.0 ± 0.5 mg / L, respectively. *Tetradesmus obliquus* and *Chlorella vulgaris* were purchased from the Institute of Hydrobiology, National Center for Aquatic Biological Resources. Before granulation, *Tetradesmus obliquus* and *Chlorella vulgaris* were cultured in a conical flask filled with BG11 medium and placed in a light incubator (SPX-250B-G). The temperature of the light incubator was maintained at 25 ± 1 °C, the light intensity was 4000 Lux, and the light / dark ratio was 14:10. During the cultivation period, the conical flask was shaken three times a day to prevent algal cells from adhering to the wall.

[0072] On the 10th day of cultivation, *Tetradesmus obliquus* and *Chlorella vulgaris* were mixed in a ratio of 1:1 and poured into the photobioreactor ( Figure 2 ), with an initial algal density of 5 × 10 6 cells / L. The initial sludge concentration was 2.8 g / L. The height-to-diameter ratio of the photobioreactor was 3, the effective volume was 6 L, the average temperature was 25 °C, and the hydraulic retention time was 8 h. The reactor was equipped with a 1.5 m LED light strip with a power of 12 W / m. The light / dark ratio was set to 2.

[0073] Aeration control was carried out in accordance with the principle of "uneven air supply". During the first 70% of the water change cycle, the dissolved oxygen was controlled at 2.5 mg / L, and during the last 30% of the water change cycle, the dissolved oxygen was controlled at 1.5 mg / L. Nitrogen was used as the auxiliary gas source for shear stress, and the nitrogen flow rate was adjusted to control the hydrodynamic shear stress at 1.5 × 10 -2 N / m 2 .

[0074] Carbon source addition was carried out in accordance with the principle of "uneven nutrition". Wastewater was simulated by manually adding chemicals, including sodium acetate, ammonium chloride, potassium dihydrogen phosphate, and trace elements. The influent COD concentration was 300 mg / L, the ammonia nitrogen concentration was 20 mg / L, and the total phosphorus concentration was 4 mg / L. During the first 70% of the water change cycle, sodium acetate was supplemented irregularly to control the COD concentration not lower than 50 mg / L; during the last 30% of the water change cycle, the COD concentration was controlled not higher than 50 mg / L.

[0075] Follow the principle of "selection pressure screening" to gradually shorten the sedimentation time during the cultivation period, so as to discharge particles and flocs with poor sedimentation and small particle size. From 1 to 20 days, the sedimentation time is 30 min; from 20 to 30 days, the sedimentation time is 20 min; from 30 to 40 days, the sedimentation time is 10 min; from 40 to 50 days, the sedimentation time is 5 min; from 50 to 60 days, the sedimentation time is 3 min.

[0076] The algal-bacterial particles cultivated according to the above method have a compact structure and stable performance. The scanning electron microscope photos are as Figure 3 shown. It can be seen from Figure 3 that the surface of the algal-bacterial particles is smooth, the structure is compact, and the spatial structure is nearly circular.

[0077] Verification of the sewage treatment performance of algal-bacterial particles in Application Example 2

[0078] Use algal-bacterial particle sludge to treat synthetic wastewater in a photobioreactor to verify its sewage treatment effect. The parameters and operating conditions of the photobioreactor are as follows: the height-diameter ratio is 3, the effective volume is 6 L, the average temperature is 25 °C, and the hydraulic retention time is 8 h. The reactor is equipped with a 1.5 m LED light strip with a power of 12 W / m. The light / dark ratio is set to 2. The algal biomass is 2.5 Chl-a / MLSS, and the sludge concentration is 3.5 mg / L.

[0079] The concentrations of each component of the synthetic wastewater are as follows: sodium acetate 400 mg / L, ammonium chloride 100 mg / L, potassium dihydrogen phosphate 20 mg / L, magnesium sulfate heptahydrate 23.9 mg / L, calcium chloride dihydrate 5.74 mg / L, sodium molybdate dihydrate 0.05 mg / L, zinc chloride 0.09 mg / L, ferric chloride hexahydrate 7.00 mg / L, copper sulfate pentahydrate 0.047 mg / L, manganese sulfate monohydrate 0.06 mg / L, cobalt sulfate heptahydrate 0.20 mg / L. Use the synthetic wastewater as the reactor influent, and the influent water quality is shown in Table 1. Continuously operate for 15 days, and the effluent COD, TN, NH4 + -N, and TP concentrations are shown in Table 2.

[0080] Table 1 Influent water quality of the algal-bacterial particle sludge reactor

[0081]

[0082] Table 2 Effluent water quality of the algal-bacterial particle sludge reactor after 15 days

[0083]

[0084] As can be seen from Table 2, the algal-bacterial granular sludge has a good treatment effect on synthetic wastewater within a retention time of 8 hours, and the effluent quality for 15 days meets the first-class A discharge standard (GB 18918-2002). The results show that the algal-bacterial granular sludge prepared by the method for preparing algal-bacterial granules based on pressure-responsive promotion of the algal-bacterial system provided by the present invention can efficiently solve the pollution of carbon, nitrogen, phosphorus, etc., effectively improve the effluent quality, and contribute to carbon emission reduction in the field of sewage treatment.

[0085] The above embodiments have described the present invention in detail, but the content described is only the preferred embodiment of the present invention and cannot be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of application of the present invention should still fall within the scope covered by the patent of the present invention.

Claims

1. A method for preparing algal-bacterial particles that promotes granulation in an algal-bacterial system based on pressure response, characterized in that: The preparation method is to co-culture the mixed microalgae cultured to the logarithmic growth phase and aerobic activated sludge in a photobioreactor. During the culture process, the principles of pressure-induced stress response are followed to jointly regulate aeration, carbon source, influent and effluent to promote granulation of the bacteria-algae system, where: Aeration regulation follows the principle of unbalanced air supply to control the dissolved oxygen level at different times; Carbon source regulation follows the principle of unbalanced nutrition to control the COD concentration at different times; Influent and effluent regulation follows the principle of gradually reducing the sedimentation time, and gradually shortens the water change sedimentation time during the culture period.

2. The method for preparing algal-bacterial particles based on pressure response to promote granulation of algal-bacterial system according to claim 1, wherein: The mixed microalgae belong to the Chlorophyta phylum, and the mixed microalgae are one or more of Tetradesmus obliquus, Chlorella vulgaris, and filamentous algae.

3. The method for preparing algal-bacterial particles based on pressure response to promote granulation of algal-bacterial system according to claim 1, wherein: The conditions for culturing pure microalgae are: temperature: 15 - 30 °C, pH: 6.5 - 7.5, light intensity: 2000 - 4000 Lux, light / dark ratio 0.8 - 1.

5. The mixed microalgae cultured for 4 - 15 days are used for granulation.

4. The method for preparing algal-bacterial particles based on pressure response to promote granulation of algal-bacterial systems according to claim 1, wherein: The aerobic activated sludge passes through a 20 - 80 mesh sieve, and the sludge concentration in the photobioreactor is controlled at 2.0 - 4.0 g / L.

5. A method for preparing bacteria-algae particles for promoting granulation of a bacteria-algae system based on pressure response according to claim 1, characterized in that: In aeration regulation, the principle of unbalanced air supply is: in the first 60 - 80% of the water change cycle, control the dissolved oxygen to be 2.0 - 4.0 mg / L, and in the last 20% - 40% of the water change cycle, control the dissolved oxygen to be 1.0 - 3.0 mg / L; In carbon source regulation, the principle of unbalanced nutrition is: in the first 20 - 60% of the water change cycle, control the COD concentration not less than 50 mg / L, and in the last 40% - 80% of the water change cycle, control the COD concentration not higher than 50 mg / L; In influent and effluent regulation, the principle of gradually reducing the sedimentation time is: the sedimentation time is 3 - 30 min, and gradually shortens the water change sedimentation time during the culture period.

6. The method for preparing algal-bacterial particles based on pressure response to promote granulation of algal-bacterial system according to claim 5, wherein: During aeration regulation, nitrogen is used as an auxiliary gas source for shear stress, and the nitrogen flow rate is adjusted to control the hydrodynamic shear stress to be 1.0´10 -2 -5.0´10 -2 N / m 2 .

7. A photobioreactor system for preparing algal-bacterial particles by using the method according to any one of claims 1-6, characterized in that: The system includes a photobioreactor, a lighting unit, a chemical dosing unit, an aeration regulation unit, and an influent and effluent control unit. The system also includes a carbon source control unit connected to the chemical dosing unit.

8. The photobioreactor system for preparing the bacteria-algae particles according to claim 7, characterized in that: The lighting unit consists of an internal waterproof LED light strip, a light intensity regulator, and a lighting duration controller, and the light / dark ratio is controlled at 1 - 5.

9. The photobioreactor system for preparing the bacterial-algal particles according to claim 7, wherein: The chemical dosing unit supplies the necessary substances for the growth of the bacteria-algae system, and the chemicals added by the chemical dosing unit include sodium acetate, ammonium chloride, potassium dihydrogen phosphate, and trace elements.

10. The photobioreactor system for preparing algal-bacterial particles according to claim 7, characterized in that: The height / diameter ratio of the photobioreactor is not less than 2, and the operating conditions of the photobioreactor include: temperature 10 - 40 °C, hydraulic retention time 6 - 12 h, intermittent influent and effluent, and one hydraulic retention time is one water change cycle.

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