A system for efficiently recovering carbon, nitrogen and phosphorus from piggery wastewater

Abstract

The invention discloses a system for efficiently recovering carbon, nitrogen and phosphorus from piggery wastewater, belonging to the technical field of sewage treatment and resource utilization; the system comprises: a UASB reactor, an ozone membrane diffusion reactor and an algae-bacteria biofilm reactor, the UASB reactor comprises a first reaction chamber and a plurality of suspended balls filled with activated carbon, the suspended balls are suspended in the wastewater in the first reaction chamber; activated carbon particles are deposited at the bottom of the first reaction chamber, the activated carbon can promote the activity of anaerobic bacteria in the anaerobic activated sludge solution and produce methane; the ozone membrane diffusion reactor comprises a second reaction chamber and an ozone oxidation unit, the ozone oxidation unit is arranged in the second reaction chamber, for utilizing ozone to degrade macromolecular organic matter; the algae-bacteria biofilm reactor comprises a third reaction chamber and a plurality of hollow fillers filled with bacteria and algae, the hollow fillers are filled in the third reaction chamber, for recovering carbon, nitrogen and phosphorus in wastewater. The invention can fully transform and recover carbon, nitrogen and phosphorus in piggery wastewater.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment and resource utilization, and in particular to a system for efficiently recovering carbon, nitrogen and phosphorus from piggery wastewater. Background Art

[0002] my country has a large population and a large demand for livestock and poultry farming, which produces a large amount of sewage. According to the "Second National Pollution Source Census Bulletin", the emissions of organic matter, ammonia nitrogen, total nitrogen and total phosphorus in livestock and poultry wastewater account for 49%, 18%, 20% and 38% of the national water pollutant emissions respectively. Pig wastewater is an important part of livestock and poultry wastewater, which is characterized by high organic matter content, high nitrogen and phosphorus content, high turbidity, strong odor, and great potential for multi-nutrient recovery. In the context of limited water resources and serious water pollution, the most effective way is to implement efficient and low-energy treatment of pig wastewater and simultaneous recovery of carbon, nitrogen and phosphorus.

[0003] Pig farm wastewater usually uses UASB anaerobic fermentation to recover carbon sources. The produced biogas slurry can be separated into clean water and concentrate through membrane filtration or its biodegradability can be improved through methods such as ozone oxidation, and then conventional sewage treatment technology can be used to achieve the simultaneous removal or recovery of carbon, nitrogen and phosphorus in the biogas slurry.

[0004] However, the existing UASB system has low space utilization and low anaerobic digestion efficiency, making it difficult to fully recover carbon, nitrogen, phosphorus and other substances in the wastewater. Summary of the invention

[0005] In view of this, it is necessary to provide a system for efficiently recovering carbon, nitrogen and phosphorus from pig wastewater to solve the problem that the existing UASB system cannot fully degrade and recover nutrients in pig wastewater.

[0006] The present invention provides a system for efficiently recovering carbon, nitrogen and phosphorus from piggery wastewater, comprising a UASB reactor, an ozone film diffusion reactor and an algae-bacteria biofilm reactor which are connected in sequence;

[0007] The UASB reactor comprises a first reaction chamber and a plurality of suspended balls filled with activated carbon, wherein anaerobic activated sludge is added to the first reaction chamber, and the suspended balls are suspended in the wastewater in the first reaction chamber; activated carbon particles are deposited at the bottom of the first reaction chamber, and the activated carbon can promote the activity of anaerobic bacteria in the anaerobic activated sludge solution to produce methane;

[0008] The ozone membrane diffusion reactor comprises a second reaction chamber and an ozone oxidation unit, wherein the second reaction chamber is capable of receiving wastewater from the first reaction chamber, and the ozone oxidation unit is disposed in the second reaction chamber to utilize ozone to degrade macromolecular organic matter;

[0009] The algae-bacteria biofilm reactor includes a third reaction chamber and a plurality of hollow fillers filled with algae and bacteria. The third reaction chamber is capable of receiving wastewater from the second reaction chamber. The hollow fillers are filled in the third reaction chamber to recover carbon, nitrogen and phosphorus in the wastewater.

[0010] Furthermore, a temperature control unit is provided on the first reaction chamber, and the temperature control unit can maintain the temperature of the lower precipitation chamber and the first reaction chamber at 35°C-38°C.

[0011] Furthermore, a gas collecting unit is provided on the top of the first reaction chamber, and the gas collecting unit can collect methane produced by anaerobic fermentation.

[0012] Furthermore, the suspended ball includes a floating sphere, a cavity is provided inside the floating sphere, the activated carbon is filled in the cavity, and the floating sphere filled with the activated carbon is suspended in the wastewater of the first reaction chamber.

[0013] Furthermore, the ozone oxidation unit includes an ozone generator and a membrane filament, the ozone generator is connected to the top of the second reaction chamber, one end of the membrane filament is connected to the ozone generator, and the other end of the membrane filament is immersed in the wastewater.

[0014] Furthermore, at least two groups of membrane filaments are suspended in the second reaction chamber, and each group of membrane filaments includes a plurality of threads.

[0015] Furthermore, the ozone membrane diffusion reactor also includes a first internal circulation unit, the two ends of which are respectively connected to the bottom and the top of the second reaction chamber to transport wastewater from the bottom to the top of the second reaction chamber, thereby promoting the contact between the hollow filler and the wastewater.

[0016] Furthermore, the hollow filler is a hollow sphere, and fluid gaps are provided between the plurality of hollow fillers. The bacteria and algae can reproduce in the fluid gaps and the hollow fillers to purify wastewater.

[0017] Furthermore, the bacteria and algae include aerobic bacteria for decomposing organic matter and microalgae for photosynthesis. The microalgae can absorb carbon dioxide from the aerobic bacteria and provide oxygen to the aerobic bacteria for fixing carbon sources. The microalgae can absorb nitrogen and phosphorus and convert them into their own biomass.

[0018] Furthermore, the algae-bacteria biofilm reactor also includes a drainage unit, which includes a DO / pH detector and a drain valve. The DO / pH detector is arranged in the third reaction chamber, and the DO / pH detector can perform water quality detection on the wastewater to be discharged. The drain valve is arranged at the bottom of the third reaction chamber, and the drain valve can discharge the purified wastewater to the outside.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) A system for efficiently recovering carbon, nitrogen and phosphorus from piggery wastewater of the present invention is provided with a UASB reactor, which includes a first reaction chamber and a plurality of filled suspended balls. Anaerobic activated sludge is added to the wastewater in the first reaction chamber. The anaerobic microorganisms in the anaerobic activated sludge can decompose organic matter in the wastewater and decompose the organic matter into inorganic methane that can be recycled and reused. Activated carbon particles are precipitated at the bottom of the first reaction chamber. The activated carbon particles are precipitated in the lower sedimentation chamber after absorbing water, and can adsorb the metabolic products of anaerobic microorganisms, reduce the toxic effects on anaerobic microorganisms, promote the activity and reproduction of microorganisms, and accelerate the decomposition of organic matter. The suspended balls are suspended in the wastewater of the first reaction chamber, and the suspended balls are filled with activated carbon powder. The suspended balls increase the contact area with the wastewater, providing more habitat and growth space for anaerobic microorganisms. The activated carbon powder can serve as an electron transfer medium to enhance the electron exchange between microorganisms, thereby accelerating the decomposition of organic matter and gas production efficiency. The setting of the suspended balls makes full use of the middle space of the first reaction chamber to prevent the activated carbon from settling at the bottom of the wastewater after absorbing water, compresses the action space of the activated carbon on anaerobic microorganisms, reduces the effect of the activated carbon on anaerobic microorganisms, and reduces the degradation efficiency of anaerobic microorganisms.

[0021] (2) The present invention provides a system for efficiently recovering carbon, nitrogen and phosphorus from piggery wastewater, which is provided with an ozone membrane diffusion reactor. The ozone membrane diffusion reactor includes a second reaction chamber and an ozone oxidation unit. The second reaction chamber can absorb wastewater that has undergone anaerobic decomposition from the first reaction chamber through a pipeline. The ozone oxidation unit is arranged in the second reaction chamber. Ozone has extremely strong oxidizing properties and can destroy the macromolecular structure of the difficult-to-degrade organic matter in the piggery biogas slurry into small molecules, thereby improving the biodegradability of the biogas slurry and facilitating the subsequent full absorption of carbon, nitrogen, phosphorus and other substances in the wastewater. At the same time, the system can realize precise control and complete utilization of ozone supply.

[0022] (3) The present invention provides a system for efficiently recovering carbon, nitrogen and phosphorus from piggery wastewater, which is provided with an algae-bacteria biofilm reactor. The algae-bacteria biofilm reactor includes a third reaction chamber and a plurality of hollow fillers filled with algae and bacteria. The third reaction chamber can absorb wastewater that has been oxidized and decomposed in the second reaction chamber through a pipeline. The hollow fillers are filled in the third reaction chamber. The hollow fillers can increase the contact area with the wastewater, providing space for the attachment and reproduction of microalgae and bacteria. The synergistic effect between the microalgae and bacteria can achieve simultaneous and efficient recovery of carbon, nitrogen and phosphorus in the pretreated wastewater without the need for external oxygen supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0024] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0025] Figure 2 It is a schematic diagram of the structure of the UASB reactor in the present invention;

[0026] Figure 3 It is a schematic diagram of the structure of the ozone membrane diffusion reactor in the present invention;

[0027] Figure 4 It is a schematic diagram of the structure of the algae-bacteria biofilm reactor in the present invention;

[0028] In the figure, 100, UASB reactor; 110, first reaction chamber; 120, suspension ball; 121, floating sphere; 130, gas collection unit;

[0029] 200, ozone membrane diffusion reactor; 210, second reaction chamber; 220, ozone oxidation unit; 221, ozone generator; 222, membrane filament; 230, first internal circulation unit;

[0030] 300. Algae-bacteria biofilm reactor; 310. The third reaction chamber; 320. Hollow filler; 330. DO / pH detector; 340. Drain valve. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0032] In this embodiment, a system for efficiently recovering carbon, nitrogen and phosphorus from pig farm wastewater is provided, including a UASB reactor 100, an ozone membrane diffusion reactor 200 and an algae-bacteria biofilm reactor 300. The system fully utilizes the internal space of the UASB reactor 100 to achieve efficient fixation and purification of carbon, and utilizes the internal space of the algae-bacteria biofilm reactor 300 to achieve sufficient fixation of nitrogen, phosphorus and residual carbon, thereby completely removing pollutants from pig farm wastewater.

[0033] See also Figures 1 to 4In this embodiment, a system for efficiently recovering carbon, nitrogen and phosphorus from piggery wastewater includes a UASB reactor 100, an ozone membrane diffusion reactor 200 and an algae-bacteria biofilm reactor 300. The UASB reactor 100 can anaerobically digest organic matter in the wastewater to produce methane and recover carbon sources. The ozone membrane diffusion reactor 200 provides ozone to the wastewater to oxidatively decompose macromolecular substances that are difficult to biodegrade, thereby improving the conversion and recovery efficiency of difficult-to-degrade carbon sources. The algae-bacteria biofilm reactor 300 utilizes the synergistic effect between microalgae and bacteria to achieve simultaneous and efficient recovery of carbon, nitrogen and phosphorus in pretreated wastewater without the need for external oxygen supply.

[0034] The UASB reactor 100 includes a first reaction chamber 110 and a plurality of filled suspension balls 120. Anaerobic activated sludge is added to the wastewater in the first reaction chamber 110. The anaerobic microorganisms in the anaerobic activated sludge can decompose the organic matter in the wastewater and decompose the organic matter into inorganic methane that can be recycled and reused. Activated carbon particles are precipitated at the bottom of the first reaction chamber 110. The activated carbon particles are precipitated in the lower sedimentation chamber after absorbing water, and can adsorb the metabolic products of anaerobic microorganisms, reduce the toxic effects on anaerobic microorganisms, promote the activity and reproduction of microorganisms, and accelerate the decomposition of organic matter. The suspension ball 120 is suspended in the wastewater of the first reaction chamber 110. The suspension ball 120 is filled with activated carbon particles. The suspension ball 120 increases the contact area with the wastewater, provides more habitat and growth space for anaerobic microorganisms, and the activated carbon particles can serve as an electron transfer medium to enhance the electron exchange between microorganisms, thereby accelerating the decomposition of organic matter and gas production efficiency. The setting of the suspension ball 120 makes full use of the middle space of the first reaction chamber 110, preventing the activated carbon from being completely precipitated at the bottom of the wastewater after absorbing water, compressing the action space of the activated carbon on anaerobic microorganisms, reducing the effect of the activated carbon on anaerobic microorganisms, and reducing the degradation efficiency of anaerobic microorganisms.

[0035] The ozone membrane diffusion reactor 200 includes a second reaction chamber 210 and an ozone oxidation unit 220. The second reaction chamber 210 can absorb wastewater that has undergone anaerobic decomposition from the first reaction chamber 110 through a pipeline. The ozone oxidation unit 220 is arranged in the second reaction chamber 210. Ozone has extremely strong oxidizing properties and can destroy the macromolecular structure of difficult-to-degrade organic matter in pig manure slurry and turn it into small molecules, thereby improving the biodegradability of the manure slurry and facilitating the subsequent full absorption of carbon, nitrogen, phosphorus and other substances in the wastewater.

[0036] The algae-bacteria biofilm reactor 300 includes a third reaction chamber 310 and a plurality of hollow fillers 320 filled with algae and bacteria. The third reaction chamber 310 can absorb wastewater that has been oxidized and decomposed by the second reaction chamber 210 through a pipeline. The hollow fillers 320 are filled in the third reaction chamber 310. The hollow fillers 320 can increase the contact area with the wastewater and provide space for the attachment and reproduction of microalgae and bacteria. The synergistic effect between the microalgae and bacteria can achieve the simultaneous and efficient recovery of carbon, nitrogen and phosphorus in the pretreated wastewater without the need for external oxygen supply.

[0037] During use, pig wastewater from the farm enters the first reaction chamber 110 from the bottom of the first reaction chamber 110 through a pipeline and under the action of a pump. The wastewater is digested and decomposed by anaerobic microorganisms, and the generated methane is gathered in the upper gas chamber and separated. The second reaction chamber 210 absorbs the wastewater that has been anaerobically decomposed from the first reaction chamber 110 through a pipeline, and the organic matter in the wastewater is oxidized and decomposed by ozone. The third reaction chamber 310 absorbs the wastewater that has been oxidized and decomposed by the second reaction chamber 210 through a pipeline, and the carbon, nitrogen and phosphorus in the wastewater are converted and fixed by bacteria and algae.

[0038] During the specific implementation process, the first reaction chamber 110 is provided with a lower sedimentation chamber, a middle reaction chamber and an upper gas chamber from bottom to top. Pig wastewater is input into the lower sedimentation chamber and the middle reaction chamber. The upper gas chamber is a cavity formed between the top of the first reaction chamber 110 and the wastewater liquid surface, which can enrich methane and output it to the outside.

[0039] In some embodiments, see Figure 2 The first reaction chamber 110 is provided with a temperature control unit, which directly acts on the wastewater in the lower sedimentation chamber and the middle reaction chamber, and can keep the temperature of the wastewater at 35°C-38°C. Within this temperature range, the metabolic rate and enzyme activity of anaerobic microorganisms (such as methanogens) in the anaerobic activated sludge reach the highest level, thereby improving the degradation efficiency of organic matter and the production of methane.

[0040] In some embodiments, the temperature control unit includes a heater and a controller. The heater may be an electric heater. The electric heater includes an electric blanket disposed on the first reaction chamber 110. The electric blanket may transfer heat to the wastewater.

[0041] The heater may be a pipeline heating system, which includes a heating pipeline arranged in the first reaction chamber 110. By introducing hot oil or hot water into the heating system, heat can be provided to the wastewater.

[0042] The controller includes a temperature sensor and a temperature controller. The sensor, such as a thermocouple, a thermistor or an infrared temperature sensor, can measure the temperature of the waste liquid in real time. The temperature controller can automatically adjust the working state of the heater according to the data fed back by the sensor to ensure that the temperature is maintained within the set range.

[0043] It should be noted that: the outer wall of the first reaction chamber 110 is wrapped with heat-insulating materials, such as glass wool, rock wool, foam plastic, etc., which can reduce heat loss.

[0044] In some embodiments, a gas collecting unit 130 is provided on the top of the first reaction chamber 110. The gas collecting unit 130 is arranged in the upper air chamber. The gas collecting unit 130 includes an air bag, which can collect methane generated by the first reaction chamber 110. The air bag is connected to the upper air chamber of the first reaction chamber 110 through a pipeline.

[0045] It should be supplemented that a three-phase separator is provided in the first reaction chamber 110, and the three-phase separator can separate the solid phase, liquid phase and gas phase in the wastewater. The three-phase separator includes a feed port, a gas phase outlet, a liquid phase outlet and a solid phase outlet. The feed port can suck wastewater into the three-phase separator. The gas phase outlet is located at the top of the separator and is used to discharge the separated methane gas, and the methane is input into the airbag. The liquid phase outlet is located in the middle of the separator and is used to discharge the separated liquid, and the liquid can be input into the second reaction chamber 210. The solid phase outlet is located at the bottom of the separator and can discharge the separated solid particles.

[0046] In some embodiments, the suspended ball 120 includes a floating sphere 121, which is a floating hollow plastic ball that can float in wastewater. A cavity is provided inside the floating sphere 121, and activated carbon is filled in the cavity. The floating sphere 121 filled with activated carbon is suspended in the wastewater in the first reaction chamber 110.

[0047] The floating sphere 121 is filled with activated carbon, which provides a larger specific surface area. The larger contact area enables the activated carbon to more effectively adsorb organic matter and pollutants, thereby improving the efficiency of wastewater treatment. In addition, the adsorption performance of the activated carbon provides a more stable microbial attachment environment, which is conducive to the growth and reproduction of anaerobic microorganisms and improves the efficiency of anaerobic digestion.

[0048] The floating sphere 121 is suspended in the wastewater. Compared with the activated carbon settled at the bottom of the wastewater, the floating sphere 121 can make full use of the internal space of the first reaction chamber 110, disperse the distribution of the activated carbon, increase the contact area with the wastewater, provide a stable growth environment, and promote the attachment and reproduction of anaerobic microorganisms on the surface of the activated carbon.

[0049] In the specific implementation process, the UASB reactor 100 was verified by miniaturization experiment using the laboratory environment. The inner diameter of the first reaction chamber 110 was 0.06m, the height was 0.47m, the residence time of the wastewater in the first reactor was 24h, the amount of activated carbon particles laid at the bottom of the first reaction chamber 110 was 3.5g, the amount of activated carbon added to the suspended ball 120 was 2.3g, the concentration of anaerobic activated sludge inside the first reaction chamber 110 was 1.1g / L, and the water quality parameters of the piggery wastewater entering the first reaction chamber 110 were: COD 2200±260mg / L, BOD5 1310±120mg / L, BOD5 / COD 59±2%, TN 216±13mg / L, TP 87±9mg / L. The activated carbon particles have adsorption properties and can create a favorable environment for anaerobic fermentation for the microorganisms by adsorbing harmful inhibitors of anaerobic digestion microorganisms. At the same time, activated carbon, as a conductive material, accelerates the electron exchange rate between anaerobic bacteria and accelerates the anaerobic fermentation rate. After being treated with activated carbon-based UASB, the water quality parameters of the biogas slurry flowing out of the first reaction chamber 110 are: COD 180±12mg / L, BOD5 44±6mg / L, BOD5 / COD 24±2%, TN 198±11mg / L, TP 82±1mg / L. The production of biomass gas is 78±4mL / day, and the methane production is 19±3mg / day, and its volume ratio in the total biomass gas is 47±3%.

[0050] In some embodiments, the first reaction chamber 110 is made of a transparent material, which may be an acrylic plate, high-strength glass, or engineering plastic, etc. This allows outsiders to observe the water quality of different parts through the reaction chamber. Sampling ports are provided at the bottom and middle of the first reaction chamber 110. The sampling ports can take samples from different depths of the first reaction chamber 110 to determine the degree of digestion of wastewater by anaerobic bacteria.

[0051] During use, pig farm wastewater enters from the bottom of the first reaction chamber 110, undergoes anaerobic fermentation from bottom to top, and fully contacts with the activated carbon particles sunk to the bottom and the floating hollow plastic balls filled with activated carbon suspended particles, eventually converting organic matter into gases such as methane. The treated pig farm wastewater is output from the upper part of the first reaction chamber 110.

[0052] In some embodiments, see Figure 3 The ozone oxidation unit 220 includes an ozone generator 221 and a membrane filament 222. The ozone generator 221 is connected to the top of the second reaction chamber 210. The ozone generator 221 can prepare ozone. Ozone has strong oxidizing properties and can decompose and destroy the macromolecular structure of organic matter in the wastewater to produce small molecules.

[0053] In addition, one end of the membrane filament 222 is connected to the ozone generator 221, and the other end of the membrane filament 222 is immersed in the wastewater. The ozone generated by the ozone generator 221 enters the membrane filament 222 at a certain air pressure after being adjusted by the flow meter. Due to the diffusion effect of the membrane, the ozone concentration in the entire second reaction chamber 210 gradually decreases from top to bottom along the membrane filament 222. The membrane filament 222 can effectively control the release rate of ozone, reduce the escape of ozone during the transmission process, and ensure that more ozone is used for actual treatment. The loss of ozone during transmission is reduced, the utilization rate of ozone is improved, and resources and costs are saved. The membrane filament 222 can also play a certain role in gas-liquid separation, ensuring that ozone is better dissolved in the liquid phase rather than directly discharged into the gas phase. Enhance the decomposition efficiency of ozone on macromolecular organic matter in wastewater.

[0054] In the specific implementation process, at least two groups of membrane wires are suspended in the second reaction chamber 210, and each group of membrane wires 222 includes multiple wires. The outer diameter of the membrane wire 222 wire is 1.35mm, and the effective length of the membrane wire 222 wire is 0.35mm. The membrane wire 222 wire is vertically bent and hung in the wastewater of the second reaction chamber 210. The number of each group of membrane wires 222 is 18, and the total number of membrane wires 222 wires is 36, with a total surface area of ​​0.05m 2 .

[0055] In some embodiments, see Figure 4 The ozone membrane diffusion reactor 200 also includes a first internal circulation unit 230, and both ends of the first internal circulation unit 230 are respectively connected to the bottom and the top of the second reaction chamber 210. The circulation unit can transport the wastewater at the bottom of the second reaction chamber 210 to the top of the second reaction chamber 210, so that the wastewater circulates in the reaction chamber, so that various substances in the wastewater are evenly distributed, and stratification in the reaction chamber is effectively avoided.

[0056] In some embodiments, the hollow filler 320 is a hollow sphere, and fluid gaps are provided between the plurality of hollow fillers 320 . Bacteria and algae can reproduce in the fluid gaps and the hollow fillers 320 to purify wastewater.

[0057] The hollow spherical filler provides a larger specific surface area, allowing bacteria and algae to attach and grow more widely on its surface and inside. The larger surface area provides more attachment points, increases the number of microorganisms and algae, and improves the efficiency of biological reactions. Furthermore, more microorganisms and algae mean higher organic matter degradation and nutrient absorption capacity, which improves the effect of wastewater treatment. At the same time, fluid gaps are provided between the multiple hollow fillers 320 to ensure that the wastewater can fully flow through the filler, enhance the contact between the wastewater and the microorganisms and algae, and enhance the degradation of organic matter and the absorption of nutrients.

[0058] In a further implementation process, the bacteria and algae include aerobic bacteria for decomposing organic matter and microalgae for photosynthesis. The microalgae can absorb carbon dioxide from aerobic bacteria and provide oxygen to aerobic bacteria to fix carbon sources. The microalgae can absorb nitrogen and phosphorus and convert them into their own biomass.

[0059] Aerobic bacteria decompose organic matter and release carbon dioxide (CO2). Microalgae absorb CO2 through photosynthesis and release oxygen (O2) for aerobic bacteria to use, forming an efficient circulation system. This mutually beneficial symbiotic circulation system improves the activity and efficiency of aerobic bacteria and microalgae, significantly improving the removal rate of organic matter and nutrients. Microalgae use the CO2 produced by aerobic bacteria for photosynthesis, fix the carbon source, and reduce the organic carbon content in the wastewater. At the same time, microalgae can also absorb nitrogen and phosphorus in the wastewater and convert them into their own biomass, thereby reducing the nitrogen and phosphorus concentrations in the wastewater and preventing eutrophication of the water body.

[0060] In some embodiments, the algae-bacteria biofilm reactor 300 further includes a drainage unit, which includes a DO / pH detector 330 and a drainage valve 340. The DO / pH detector 330 is disposed in the third reaction chamber 310, and the DO / pH detector 330 can perform real-time water quality detection on the wastewater to be discharged. The drainage valve 340 is disposed at the bottom of the third reaction chamber 310, and the drainage valve 340 can discharge the purified wastewater to the outside. In the specific implementation process, the drainage valve 340 is specifically a solenoid valve, and the DO / pH detector 330 is electrically connected to the solenoid valve through a controller. When the DO / pH detector 330 detects that the water quality meets the standard, the solenoid valve can be opened to transport the purified wastewater to the outside.

[0061] The drain valve 340 is arranged at the bottom of the third reaction chamber 310, and the DO / pH detector 330 is connected to the drain valve 340. The DO / pH detector can monitor the dissolved oxygen (DO) and pH value in the algae-bacteria biofilm reactor 300 in real time to ensure that the water quality meets the standards.

[0062] In some embodiments, the algae-bacteria biofilm reactor 300 also includes a second internal circulation unit, and both ends of the second internal circulation unit are respectively connected to the bottom and top of the third reaction chamber 310, so that the wastewater located in the lower layer can be transported to the upper layer of the third reaction chamber 310, thereby promoting the contact between microalgae and bacteria and the wastewater, extending the contact time, increasing the contact area, and improving the purification efficiency of sewage.

[0063] The first circulation unit and the second circulation unit include a water pump and a pipeline. The two ends of the water pump are connected to the top and the bottom of the chamber body through the pipeline respectively, so that the wastewater at the bottom of the reaction chamber can be transported to the top of the reaction chamber.

[0064] In the specific implementation process, the algae-bacteria biofilm reactor 300 was verified by miniaturization experiments in a laboratory environment. The third reaction chamber 310 has the same shape and structure as the first reaction chamber 110. The third reaction chamber 310 is placed vertically on the ground. The third reaction chamber 310 is filled with 122 fillers, and the total volume of the fillers is 192.5 ml. The sludge concentration is 4.2 g / L, and the algae liquid concentration is 2.79 g / L. After inoculation, the concentration in the third reaction chamber 310 is calculated based on the sludge concentration of 1.0 g / L and the algae liquid concentration of 0.5 g / L. The volume of sludge to be added to the first reaction chamber 110 is 185.6 ml, and the volume of algae liquid to be added is 139.7 ml. The water quality parameters of sewage after treatment with bacteria-algae biofilm are: COD 24±5mg / L, BOD5 4.2±0.5mg / L, BOD5 / COD 19±1%, TN 6.8±1.4mg / L, TP 0.8±0.1mg / L.

[0065] The third reaction chamber 310 is also made of a transparent material, and can provide supplementary light from the outside to the algae inside.

[0066] Workflow: The first reaction chamber 110, the second reaction chamber 210 and the third reaction chamber 310 are connected in sequence, and the piggery wastewater passes through the first reaction chamber 110, the second reaction chamber 210 and the third reaction chamber in sequence. The piggery wastewater can convert most of the organic matter into biomass gas-methane through anaerobic reaction in the UASB reactor 100, and the organic nitrogen and phosphorus are released into the solution, which is convenient for subsequent treatment and recovery. The granular activated carbon suspended at the bottom and middle of the reactor promotes the anaerobic conversion rate through adsorption, enhanced electron transfer and other effects, and increases the yield and output of methane and the release of nitrogen and phosphorus. The biogas slurry produced by the UASB reactor 100 has poor biodegradability. After entering the ozone membrane diffusion reactor 200, it is fully contacted with the ozone diffused and supplied by the membrane filaments 222. The refractory macromolecular organic matter is converted into easily biodegradable small molecular organic matter under the oxidation of ozone, and then enters the subsequent algae biofilm reactor 300. In the algae-bacteria biofilm reactor 300, microalgae and bacteria work together to achieve simultaneous and efficient fixation of carbon, nitrogen and phosphorus: part of carbon, nitrogen and phosphorus can be fixed through assimilation and then converted into biomass; part of nitrogen and phosphorus can be directly fixed in the biofilm through microbial adsorption; part of nitrogen is converted into nitrogen gas through traditional nitrification and denitrification; microalgae photosynthesis achieves carbon dioxide, nitrogen and phosphorus fixation, while producing oxygen, and part of organic matter is converted into carbon dioxide through aerobic mineralization of bacteria to supply microalgae for photosynthesis. The whole process does not require exogenous oxygen supply, and the algae biofilm achieves the fixation of nitrogen, phosphorus and organic matter in the biogas slurry, and then converts it into algae biomass, while the concentrations of carbon, nitrogen and phosphorus in the pig biogas slurry gradually decrease, and the water overflows from the outlet hole and meets the discharge standards.

[0067] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed in the present invention should be covered by the present invention.

Claims

1. A system for efficiently recovering carbon, nitrogen and phosphorus from piggery wastewater, characterized in that: It includes a UASB reactor, an ozone film diffusion reactor and an algae-bacteria biofilm reactor which are connected in sequence; The UASB reactor includes a first reaction bin and a plurality of suspended balls filled with activated carbon powder, wherein anaerobic activated sludge is added to the first reaction bin, and the suspended balls are suspended in the wastewater in the first reaction bin, making full use of the middle space of the first reaction bin; activated carbon particles are deposited at the bottom of the first reaction bin, and the suspended balls increase the contact area with the wastewater, providing more habitat and growth space for anaerobic microorganisms, and the activated carbon can promote the activity of anaerobic bacteria in the anaerobic activated sludge solution to produce methane; The ozone membrane diffusion reactor comprises a second reaction chamber and an ozone oxidation unit, wherein the second reaction chamber is capable of receiving wastewater from the first reaction chamber, and the ozone oxidation unit is disposed in the second reaction chamber to utilize ozone to degrade macromolecular organic matter; The algae-bacteria biofilm reactor includes a third reaction chamber and a plurality of hollow fillers filled with algae and bacteria. The third reaction chamber is capable of receiving wastewater from the second reaction chamber. The hollow fillers are filled in the third reaction chamber to recover carbon, nitrogen and phosphorus in the wastewater.

2. The system for efficiently recovering carbon, nitrogen and phosphorus from piggery wastewater according to claim 1 is characterized in that: The first reaction chamber is provided with a temperature control unit, and the temperature control unit can maintain the temperature of the first reaction chamber at 35°C-38°C.

3. The system for efficiently recovering carbon, nitrogen and phosphorus from piggery wastewater according to claim 1 is characterized in that: A gas collecting unit is provided on the top of the first reaction chamber, and the gas collecting unit can collect methane produced by anaerobic fermentation.

4. The system for efficiently recovering carbon, nitrogen and phosphorus from piggery wastewater according to claim 1 is characterized in that: The suspended ball comprises a floating sphere, a cavity is provided inside the floating sphere, the activated carbon is filled in the cavity, and the floating sphere filled with the activated carbon is suspended in the wastewater of the first reaction chamber.

5. The system for efficiently recovering carbon, nitrogen and phosphorus from piggery wastewater according to claim 1 is characterized in that: The ozone oxidation unit includes an ozone generator and a membrane filament. The ozone generator is connected to the top of the second reaction chamber, one end of the membrane filament is connected to the ozone generator, and the other end of the membrane filament is immersed in the wastewater.

6. The system for efficiently recovering carbon, nitrogen and phosphorus from piggery wastewater according to claim 5, characterized in that: At least two groups of membrane filaments are suspended in the second reaction chamber, and each group of membrane filaments includes a plurality of wires.

7. The system for efficiently recovering carbon, nitrogen and phosphorus from piggery wastewater according to claim 6, characterized in that: The ozone membrane diffusion reactor also includes a first internal circulation unit, both ends of which are respectively connected to the bottom and top of the second reaction chamber to transport wastewater from the bottom to the top of the second reaction chamber, thereby promoting contact between the hollow filler and the wastewater.

8. The system for efficiently recovering carbon, nitrogen and phosphorus from piggery wastewater according to claim 1 is characterized in that: The hollow filler is a hollow sphere, and fluid gaps are provided between a plurality of the hollow fillers. The bacteria and algae can reproduce in the fluid gaps and the hollow fillers to purify wastewater.

9. The system for efficiently recovering carbon, nitrogen and phosphorus from piggery wastewater according to claim 8, characterized in that: The bacteria and algae include aerobic bacteria for decomposing organic matter and microalgae for photosynthesis. The microalgae can absorb carbon dioxide from the aerobic bacteria and provide oxygen to the aerobic bacteria for fixing carbon sources. The microalgae can absorb nitrogen and phosphorus and convert them into their own biomass.

10. The system for efficiently recovering carbon, nitrogen and phosphorus from piggery wastewater according to claim 1, characterized in that: The algae-bacteria biofilm reactor also includes a drainage unit, which includes a DO / pH detector and a drain valve. The DO / pH detector is arranged in the third reaction chamber, and the DO / pH detector can perform water quality detection on the wastewater to be discharged. The drain valve is arranged at the bottom of the third reaction chamber, and the drain valve can discharge the purified wastewater to the outside.

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