A device and method for realizing efficient recovery of phosphorus and PHAs by fermenting denitrifying phosphorus removal granular sludge

Abstract

The application discloses a device and method for realizing efficient recovery of phosphorus and PHAs by fermenting denitrifying phosphorus removal granular sludge, and belongs to the technical field of sewage biological treatment. The device comprises a hard-biodegradable carbon source, ammonia nitrogen and phosphate influent tank, a nitrate nitrogen influent tank, a granular sludge reactor, a PHAs recovery tank, a phosphorus and ammonia nitrogen effluent tank, a magnesium solution influent tank, a struvite reactor, a phosphorus recovery tank, an effluent tank and an online monitoring system. The method comprises an anaerobic stage, hard-biodegradable carbon source is converted into easily-biodegradable carbon source and stored as PHAs and phosphorus is released, supernatant and granular sludge are discharged at the end of the anaerobic stage to realize recovery of phosphorus and PHAs, and sludge granulation is promoted by regulating non-stirring and sedimentation time of influent; and the method further comprises an anoxic stage, denitrification and simultaneous phosphorus uptake are realized. The application solves the technical problems that denitrifying phosphorus removal bacteria cannot utilize hard-biodegradable carbon source to realize simultaneous recovery of phosphorus and PHAs, and struvite formation needs to regulate phosphate and pH.

Description

Technical Field

[0001] This invention belongs to the field of wastewater biological treatment technology, and more specifically, it relates to an apparatus and method for achieving efficient recovery of phosphorus and PHAs from fermented denitrification phosphorus removal granular sludge. Background Technology

[0002] Phosphorus is an essential element in agricultural production, and with population growth and increasing food demand, the demand for phosphorus is showing a significant upward trend.

[0003] Aerobic phosphorus removal technology can recover phosphorus resources by discharging flocculent sludge at the end of the aerobic stage. However, aerobic phosphorus removal technology consumes a large amount of oxygen and carbon sources and cannot achieve simultaneous recovery of PHAs. At the same time, the flocculent sludge used in aerobic phosphorus removal technology has low biomass and poor settling properties, which limits its phosphorus recovery load.

[0004] Existing technologies also mention denitrification for phosphorus removal, which can simultaneously recover phosphorus resources and remove nitrate and nitrogen pollutants. Compared to aerobic phosphorus removal, denitrification can save approximately 50% of carbon source consumption and 30% of aeration. However, denitrification recovers phosphorus resources by discharging flocculent sludge at the end of the anoxic phase, and therefore cannot achieve simultaneous recovery of PHAs. Furthermore, the flocculent sludge used in denitrification has low biomass and poor settling properties, which also limits phosphorus recovery capacity.

[0005] Meanwhile, existing aerobic phosphorus removal and denitrification technologies can only utilize readily biodegradable carbon sources in wastewater, which are often scarce. At the same time, more than 50% of the recalcitrant carbon sources in wastewater cannot be utilized. Furthermore, to achieve efficient phosphorus removal, additional readily biodegradable carbon sources are usually required, significantly increasing phosphorus recovery costs.

[0006] Currently, phosphorus resource recovery is typically achieved through struvite crystallization. Struvite (NH4MgPO4•6H2O) is composed of ammonia nitrogen, phosphate, and magnesium salts, and it forms more readily at pH values ​​greater than 8.0. Therefore, the formation of struvite often requires the addition of ammonia nitrogen and pH adjusters, increasing operational complexity and cost.

[0007] Therefore, the applicant believes that how to achieve efficient recovery of phosphorus and PHAs while making full use of recalcitrant carbon sources, and how to eliminate the need for additional ammonia nitrogen and pH adjusters during the recovery process of struvite, is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to provide an apparatus and method for achieving efficient recovery of phosphorus and PHAs from fermented denitrification granular sludge. This method fully utilizes recalcitrant carbon sources and leverages anaerobic end-of-pipe phosphorus-rich supernatant and granular sludge to achieve efficient recovery of phosphorus and PHAs. Furthermore, by real-time control of phosphorus and ammonia nitrogen concentrations and utilizing the natural pH rise during denitrification, this invention eliminates the need for additional ammonia nitrogen and pH adjusters during struvite recovery.

[0009] To achieve the above technical objectives, this application employs the following technical solution:

[0010] The apparatus for efficient recovery of phosphorus and PHAs from fermented denitrification granular sludge, as described in this invention, comprises a series of sequentially connected inlet tanks for a recalcitrant carbon source, ammonia nitrogen, and phosphate; an inlet tank for nitrate nitrogen; a granular sludge reactor; a PHAs recovery tank; an outlet tank for phosphorus and ammonia nitrogen; an outlet tank for magnesium solution; a struvite reactor; a phosphorus recovery tank; an outlet tank; and an online monitoring and control system. The inlet tanks for the recalcitrant carbon source, ammonia nitrogen, and phosphate are connected to the granular sludge reactor via a first inlet pump; the nitrate nitrogen inlet tank is connected to the granular sludge reactor via a second inlet pump; and the PHAs recovery tank is connected to the granular sludge reactor via a first sludge discharge pump. The following connections are made: The phosphorus and ammonia nitrogen effluent tanks are connected to the granular sludge reactor via a first drainage pump; the phosphorus and ammonia nitrogen effluent tanks are connected to the struvite reactor via a third influent pump; the magnesium solution influent tank is connected to the struvite reactor via a fourth influent pump; the phosphorus recovery tank is connected to the struvite reactor via a second sludge discharge pump; the effluent tank is connected to the struvite reactor via a second drainage pump; the granular sludge reactor is connected to the online monitoring and control system via a first phosphate concentration sensor, a nitrate concentration sensor, a pH sensor, and an ammonia nitrogen concentration sensor; the struvite reactor is connected to the online monitoring and control system via a second phosphate concentration sensor.

[0011] The inlet tank for the recalcitrant carbon source, ammonia nitrogen, and phosphate is equipped with a first overflow pipe and a first vent valve.

[0012] The nitrate inlet tank is equipped with a second overflow pipe and a second vent valve;

[0013] The granular sludge reactor is equipped with a first agitator, a first inlet pump, a second inlet pump, a first sludge discharge pump, a first drain pump, a first phosphate concentration sensor, a nitrate concentration sensor, a pH sensor, and an ammonia nitrogen concentration sensor.

[0014] The PHAs recycling bin is equipped with a third overflow pipe and a third vent valve;

[0015] The phosphorus and ammonia nitrogen outlet tanks are equipped with a fourth overflow pipe and a fourth vent valve;

[0016] The magnesium solution inlet tank is equipped with a fifth overflow pipe and a fifth vent valve;

[0017] The struvite reactor is equipped with a third inlet pump, a fourth inlet pump, a second agitator, a third agitator, a second phosphate concentration sensor, a second sludge discharge pump, and a second drain pump.

[0018] The phosphorus recovery tank is equipped with a sixth overflow pipe and a sixth vent valve;

[0019] The outlet tank is equipped with a seventh overflow pipe and a seventh vent valve;

[0020] The online monitoring and control system includes a first inlet pump relay, a pH sensor relay, an ammonia nitrogen concentration sensor relay, a first agitator relay, a first phosphate concentration sensor relay, a nitrate concentration sensor relay, a first sludge discharge pump relay, a first drain pump relay, a second inlet pump relay, a third inlet pump relay, a second agitator relay, a third agitator relay, a second phosphate concentration sensor relay, a second sludge discharge pump relay, a fourth inlet pump relay, a second drain pump relay, an A / D converter, a D / A converter, and a computer.

[0021] The online monitoring and control system is connected as follows: a first inlet pump relay is connected to the first inlet pump; a pH sensor relay is connected to the pH sensor; an ammonia nitrogen concentration sensor relay is connected to the ammonia nitrogen concentration sensor; a first stirrer relay is connected to the first stirrer; a first phosphate concentration sensor relay is connected to the first phosphate concentration sensor; a nitrate concentration sensor relay is connected to the nitrate concentration sensor; a first sludge discharge pump relay is connected to the first sludge discharge pump; a first drainage pump relay is connected to the first drainage pump; a second inlet pump relay is connected to the second inlet pump; and a third inlet pump relay is connected to... The third inlet pump is connected; the second agitator relay is connected to the second agitator; the third agitator relay is connected to the third agitator; the second phosphate concentration sensor relay is connected to the second phosphate concentration sensor; the second sludge discharge pump relay is connected to the second sludge discharge pump; the fourth inlet pump relay is connected to the fourth inlet pump; the second drain pump relay is connected to the second drain pump; the online monitoring and control system converts analog signals into digital signals and transmits them to the computer through a signal converter A / D interface and cable; the computer transmits digital instructions to the online monitoring and control system through a cable and a signal converter D / A interface.

[0022] This invention also provides a device for achieving efficient recovery of phosphorus and PHAs using fermented denitrification granular sludge, and a method for achieving efficient recovery of phosphorus and PHAs using fermented denitrification granular sludge, comprising the following steps:

[0023] I. Cultivation of fermented denitrification phosphorus removal granular sludge:

[0024] 1) Add activated sludge from the wastewater treatment plant to the granular sludge reactor, and control the sludge concentration at 2000 mg / L-8000 mg / L;

[0025] 2) Start the first influent pump to pump a volume of V1 of recalcitrant carbon source, ammonia nitrogen, and phosphate into the granular sludge reactor, controlling V1 to be 40%-80% of the effective volume V of the reactor;

[0026] 3) Control the settling time to be greater than 1 hour, start the first drainage pump, and pump the supernatant containing phosphate and ammonia nitrogen with a volume of V2 into the phosphorus and ammonia nitrogen outlet tank, controlling V2 to be 30%-90% of V1;

[0027] 4) Start the first mixer, and stop mixing when the sewage and sludge are fully mixed;

[0028] 5) Control the sedimentation time to be less than 20 minutes, start the first sludge discharge pump, and discharge the fermentation denitrification phosphorus removal granular sludge with a volume of V3 into the PHAs recovery tank. V3 is the difference between V1 and V2.

[0029] 6) Start the second inlet pump to pump a volume of V4 of nitrate nitrogen inlet water into the granular sludge reactor, and control the molar ratio of nitrate nitrogen to phosphate concentration in the granular sludge reactor to be greater than 1.5.

[0030] 7) Start the first stirrer and stop stirring when the nitrate concentration drops to 0 mg / L;

[0031] 8) Control the sedimentation time to be greater than 10 minutes, start the first drainage pump, and pump the supernatant with a volume of V4 into the phosphorus and ammonia nitrogen outlet tank.

[0032] 9) Repeat steps 2-8 until the proportion of granular sludge with a particle size greater than 200μm in the mixed sludge is greater than 30%, and control the settling time in step 5 to less than 10min.

[0033] 10) Repeat steps 2-8 until the proportion of granular sludge with a particle size greater than 200 μm is greater than 50% of the mixed sludge, the molar ratio of phosphate to ammonia nitrogen in the anaerobic granular sludge reactor is greater than 1.0, and the pH value in the anoxic granular sludge reactor is greater than 8.5. This indicates that the cultivation of fermented denitrification phosphorus removal granular sludge has been finally achieved.

[0034] II. String of guano recycling:

[0035] 1) Start the third inlet pump to pump ammonia nitrogen and phosphate inlet water with a volume of V5 into the struvite reactor, where V5 is the sum of V2 and V4;

[0036] 2) Start the fourth inlet pump to pump the magnesium solution into the struvite reactor, and control the molar ratio of magnesium ions to phosphate ions to be 1.0.

[0037] 3) Start the second and third stirrers, and stop stirring when the phosphate concentration drops to 0 mg / L;

[0038] 4) Control the sedimentation time to be greater than 10 minutes, then start the second drainage pump to discharge the effluent into the effluent tank;

[0039] 5) Start the second sludge pump to discharge the struvite sediment into the phosphorus recovery tank, thus ultimately recovering phosphorus resources in the form of struvite.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1. Compared with denitrification phosphorus removal technology, the fermented denitrification phosphorus removal granular sludge cultivated in this invention can make full use of recalcitrant carbon sources.

[0042] 2. Compared with traditional aerobic phosphorus removal and denitrification phosphorus removal technologies, this invention solves the technical problem of simultaneous recovery of phosphorus and PHAs by recovering phosphorus-rich supernatant and granular sludge at the end of anaerobic treatment.

[0043] 3. Compared with aerobic phosphorus removal and denitrification phosphorus removal technologies, the granular sludge used in this invention can significantly increase the biomass per unit volume and settling performance in the reactor, thereby significantly increasing the recovery load of phosphorus and PHAs.

[0044] 4. Compared with aerobic phosphorus removal technology, the fermented denitrification phosphorus removal granular sludge cultivated in this invention can reduce the carbon source required for aerobic respiration, thereby significantly increasing the yield of PHAs. Furthermore, this invention can also achieve simultaneous nitrogen removal and further increase the yield of PHAs by saving the carbon source required for nitrogen removal.

[0045] 5. This invention provides a method for granulation of fermentation-based denitrification and phosphorus removal sludge, which promotes granular sludge formation through anaerobic influent without stirring, enhanced internal carbon source storage during fermentation, and controlled sedimentation time.

[0046] 6. This invention provides an economical and efficient method for struvite recovery. By controlling the concentrations of phosphorus and ammonia nitrogen in real time and utilizing the natural rise of pH value during denitrification phosphorus removal, the method eliminates the need for additional ammonia nitrogen and pH adjusters during struvite recovery, effectively reducing the cost of phosphorus recovery. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the device for achieving efficient recovery of phosphorus and PHAs from fermented denitrification granular sludge as described in this invention.

[0048] In the diagram: 1 is the inlet tank for recalcitrant carbon source, ammonia nitrogen, and phosphate; 2 is the inlet tank for nitrate nitrogen; 3 is the granular sludge reactor; 4 is the PHAs recovery tank; 5 is the effluent tank for phosphorus and ammonia nitrogen; 6 is the inlet tank for magnesium solution; 7 is the struvite reactor; 8 is the phosphorus recovery tank; 9 is the effluent tank; 10 is the online monitoring and control system; 1.1 is the first overflow pipe; 1.2 is the first vent valve; 2.1 is the second overflow pipe; 2.2 is the second vent valve; 3.1 is the first agitator; 3.2 is the first inlet pump; 3.3 is the second inlet pump; 3.4... 3.5 is the first sludge pump; 3.6 is the first drainage pump; 3.7 is the first phosphate concentration sensor; 3.8 is the nitrate concentration sensor; 3.9 is the pH sensor; 4.1 is the third overflow pipe; 4.2 is the third vent valve; 5.1 is the fourth overflow pipe; 5.2 is the fourth vent valve; 6.1 is the fifth overflow pipe; 6.2 is the fifth vent valve; 7.1 is the third inlet pump; 7.2 is the fourth inlet pump; 7.3 is the second agitator; 7.4 is the third agitator; 7.5 is the second phosphate concentration sensor. 7.6 is the second sludge pump, 7.7 is the second drainage pump; 8.1 is the sixth overflow pipe, 8.2 is the sixth vent valve; 9.1 is the seventh overflow pipe, 9.2 is the seventh vent valve; 10.1 is the first inlet pump relay, 10.2 is the pH sensor relay, 10.3 is the ammonia nitrogen concentration sensor relay, 10.4 is the first agitator relay, 10.5 is the first phosphate concentration sensor relay, 10.6 is the nitrate concentration sensor relay, 10.7 is the first sludge pump relay, 10.8... 10.9 is the relay for the first drain pump; 10.10 is the relay for the second inlet pump; 10.11 is the relay for the third inlet pump; 10.12 is the relay for the third agitator; 10.13 is the relay for the second phosphate concentration sensor; 10.14 is the relay for the second sludge pump; 10.15 is the relay for the fourth inlet pump; 10.16 is the relay for the second drain pump; 10.17 is the A / D converter interface; 10.18 is the D / A converter interface; and 10.19 is the computer. Detailed Implementation

[0049] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0050] The technical principle of this invention is as follows: Using activated sludge from a wastewater treatment plant as seed sludge, during anaerobic influent, recalcitrant carbon sources are fermented and converted into readily biodegradable carbon sources, while simultaneously being stored as intracellular PHAs and releasing phosphorus. At the end of the anaerobic process, the supernatant and granular sludge are discharged separately to achieve efficient recovery of phosphorus and PHAs. During this process, the formation of dense, fermented, denitrifying, and phosphorus-removing granular sludge is promoted through anaerobic non-stirring, fermentation enhancement, and controlled sedimentation time screening. In the anoxic stage, the remaining granular sludge utilizes intracellular PHAs to absorb phosphorus, remove nitrogen, and generate alkalinity, thus increasing the pH value. This invention can efficiently achieve simultaneous recovery of phosphorus and PHAs while fully utilizing recalcitrant carbon sources, and simultaneously solves the technical problem of needing to add ammonia nitrogen and pH adjusters during struvite recovery.

[0051] Example 1: As Figure 1 As shown, an apparatus for efficient recovery of phosphorus and PHAs from fermented denitrification granular sludge includes, in sequence, a recalcitrant carbon source, ammonia nitrogen, and phosphate inlet tank 1; a nitrate nitrogen inlet tank 2; a granular sludge reactor 3; a PHAs recovery tank 4; a phosphorus and ammonia nitrogen outlet tank 5; a magnesium solution inlet tank 6; a struvite reactor 7; a phosphorus recovery tank 8; an outlet tank 9; and an online monitoring and control system 10. The recalcitrant carbon source, ammonia nitrogen, and phosphate inlet tank 1 is connected to the granular sludge reactor 3 via a first inlet pump 3.2; the nitrate nitrogen inlet tank 2 is connected to the granular sludge reactor 3 via a second inlet pump 3.3; the PHAs recovery tank 4 is connected to the granular sludge reactor 3 via a first sludge discharge pump 3.4; and the phosphorus and ammonia nitrogen outlet tank 5... The first drainage pump 3.5 is connected to the granular sludge reactor 3; the phosphorus and ammonia nitrogen effluent tank 5 is connected to the struvite reactor 7 via the third influent pump 7.1; the magnesium solution influent tank 6 is connected to the struvite reactor 7 via the fourth influent pump 7.2; the phosphorus recovery tank 8 is connected to the struvite reactor 7 via the second sludge discharge pump 7.6; the effluent tank 9 is connected to the struvite reactor 7 via the second drainage pump 7.7; the granular sludge reactor 3 is connected to the online monitoring and control system 10 via the first phosphate concentration sensor 3.6, the nitrate concentration sensor 3.7, the pH sensor 3.8, and the ammonia nitrogen concentration sensor 3.9; the struvite reactor 7 is connected to the online monitoring and control system 10 via the second phosphate concentration sensor 7.5.

[0052] The recalcitrant carbon source, ammonia nitrogen, and phosphate inlet tank 1 is equipped with a first overflow pipe 1.1 and a first vent valve 1.2; the nitrate nitrogen inlet tank 2 is equipped with a second overflow pipe 2.1 and a second vent valve 2.2; the granular sludge reactor 3 is equipped with a first stirrer 3.1, a first inlet pump 3.2, a second inlet pump 3.3, a first sludge discharge pump 3.4, a first drain pump 3.5, a first phosphate concentration sensor 3.6, a nitrate concentration sensor 3.7, a pH sensor 3.8, and an ammonia nitrogen concentration sensor. Unit 3.9; PHAs recovery tank 4 is equipped with a third overflow pipe 4.1 and a third vent valve 4.2; phosphorus and ammonia nitrogen outlet tank 5 is equipped with a fourth overflow pipe 5.1 and a fourth vent valve 5.2; magnesium solution inlet tank 6 is equipped with a fifth overflow pipe 6.1 and a fifth vent valve 6.2; struvite reactor 7 is equipped with a third inlet pump 7.1, a fourth inlet pump 7.2, a second stirrer 7.3, a third stirrer 7.4, a second phosphate concentration sensor 7.5, a second sludge pump 7.6, and a second drain pump 7.7; The phosphorus recovery tank 8 is equipped with a sixth overflow pipe 8.1 and a sixth vent valve 8.2; the outlet tank 9 is equipped with a seventh overflow pipe 9.1 and a seventh vent valve 9.2; the online monitoring and control system 10 includes a first inlet pump relay 10.1, a pH sensor relay 10.2, an ammonia nitrogen concentration sensor relay 10.3, a first agitator relay 10.4, a first phosphate concentration sensor relay 10.5, a nitrate concentration sensor relay 10.6, a first sludge discharge pump relay 10.7, and a first... Drain pump relay 10.8, second inlet pump relay 10.9, third inlet pump relay 10.10, second agitator relay 10.11, third agitator relay 10.12, second phosphate concentration sensor relay 10.13, second sludge pump relay 10.14, fourth inlet pump relay 10.15, second drain pump relay 10.16, signal converter A / D converter interface 10.17, signal converter D / A converter interface 10.18, and computer 10.19.The online monitoring and control system 10 includes the following connections: First inlet pump relay 10.1 is connected to first inlet pump 3.2; pH sensor relay 10.2 is connected to pH sensor 3.8; ammonia nitrogen concentration sensor relay 10.3 is connected to ammonia nitrogen concentration sensor 3.9; first stirrer relay 10.4 is connected to first stirrer 3.1; first phosphate concentration sensor relay 10.5 is connected to first phosphate concentration sensor 3.6; nitrate concentration sensor relay 10.6 is connected to nitrate concentration sensor 3.7; first sludge discharge pump relay 10.7 is connected to first sludge discharge pump 3.4; first drainage pump relay 10.8 is connected to first drainage pump 3.5; second inlet pump relay 10.9 is connected to second inlet pump 3.3; and third inlet pump relay 10.10 is connected to third inlet pump 3.5. Water pump 7.1 is connected; second agitator relay 10.11 is connected to second agitator 7.3; third agitator relay 10.12 is connected to third agitator 7.4; second phosphate concentration sensor relay 10.13 is connected to second phosphate concentration sensor 7.5; second sludge pump relay 10.14 is connected to second sludge pump 7.6; fourth inlet pump relay 10.15 is connected to fourth inlet pump 7.2; second drain pump relay 10.16 is connected to second drain pump 7.7; online monitoring and control system 10 converts analog signals into digital signals and transmits them to computer 10.19 through signal converter A / D converter interface 10.17 and cable; computer 10.19 transmits digital commands to online monitoring and control system 10 through cable and signal converter D / A converter interface 10.18.

[0053] During the experiment, starch, ammonium chloride, dipotassium hydrogen phosphate, tap water, and 0.3 ml / L nutrient solution were used to simulate the influent of recalcitrant carbon sources, ammonia nitrogen, and phosphate. The concentrations of recalcitrant carbon sources, ammonia nitrogen, and phosphate were 800 mg COD / L, 50 mg N / L, and 6 mg P / L, respectively. Sodium nitrate and tap water were used to simulate the influent of nitrate nitrogen, with a nitrate nitrogen concentration of 20 mg N / L. Magnesium chloride hexahydrate and tap water were used to simulate the influent of magnesium solution, with a magnesium ion concentration of 500 mg / L. The nutrient solution contains: 5g / L EDTA, 5g / L FeSO4, 15g / L EDTA, 0.014g / L H3BO3, 0.25g / L CuSO4·5H2O, 0.22g / L NaMoO4·2H2O, 0.99g / L LnCl2·4H2O, 0.43g / L ZnSO4·7H2O, and 0.19g / L NiCl2·6H2O.

[0054] Test reactor such as Figure 1 As shown, the granular sludge reactor 3 and the struvite reactor 7 have volumes of 10L and 14L, respectively.

[0055] The specific operation steps are as follows:

[0056] I. Cultivation of fermented denitrification phosphorus removal granular sludge:

[0057] 1) Add activated sludge from the wastewater treatment plant to granular sludge reactor 3, and control the sludge concentration at 6000 mg / L;

[0058] 2) Start the first influent pump 3.2 to pump 6L of recalcitrant carbon source, ammonia nitrogen and phosphate into the granular sludge reactor 3;

[0059] 3) Control the settling time to 2 hours, start the first drainage pump 3.5, and pump 5L of supernatant containing phosphate and ammonia nitrogen into the phosphorus and ammonia nitrogen outlet tank 5;

[0060] 4) Start the first agitator 3.1, and stop agitating when the sewage and sludge are fully mixed;

[0061] 5) Control the sedimentation time to 10 minutes, start the first sludge discharge pump 3.4, and discharge 1L of fermentation denitrification phosphorus removal granular sludge into the PHAs recovery tank 4.

[0062] 6) Start the second inlet pump 3.3 to pump 4L of nitrate nitrogen inlet water into granular sludge reactor 3, and control the molar ratio of nitrate nitrogen to phosphate concentration in granular sludge reactor 3 to be 1.7.

[0063] 7) Start the first stirrer 3.1, and stop stirring when the nitrate concentration drops to 0 mg / L;

[0064] 8) Control the sedimentation time to 20 minutes, start the first drainage pump 3.5, and pump 4L of supernatant into the phosphorus and ammonia nitrogen outlet tank 5;

[0065] 9) Repeat steps 2-8 until the proportion of granular sludge with a particle size greater than 200μm in the mixed sludge is 45%, and control the sedimentation time in step 5 to 5min.

[0066] 10) Repeat steps 2-8 until the proportion of granular sludge with a particle size greater than 200μm is 70% of the mixed sludge, the molar ratio of phosphate to ammonia nitrogen in the anaerobic granular sludge reactor 3 is 1.2, and the pH value in the anoxic granular sludge reactor 3 is 8.6. This indicates that the cultivation of fermented denitrification phosphorus removal granular sludge has been finally achieved.

[0067] II. String of guano recycling:

[0068] 1) Start the third inlet pump 7.1 to pump 9L of ammonia nitrogen and phosphate inlet water into struvite reactor 7;

[0069] 2) Start the fourth inlet pump 7.2 to pump the magnesium solution into the struvite reactor 7, and control the molar ratio of magnesium ions to phosphate ions to be 1.0;

[0070] 3) Start the second stirrer 7.3 and the third stirrer 7.4, and stop stirring when the phosphate concentration drops to 0 mg / L;

[0071] 4) Control the sedimentation time to 30 minutes, start the second drainage pump 7.7, and discharge the effluent into the effluent tank 9;

[0072] 5) Start the second sludge pump 7.6 to discharge the struvite sediment into the phosphorus recovery tank 8, and finally realize the recovery of phosphorus resources in the form of struvite.

[0073] The experimental results showed that in the fermented denitrification phosphorus removal granular sludge, particles with a diameter greater than 200 μm accounted for 70%. Under the condition that the starch utilization rate reached 69%, the PHA content could reach 0.23 g / g sludge, and the phosphorus recovery rate was 92%. Among them, phosphorus was recovered in the form of struvite, with an average particle size of 0.50 mm and a purity of 85%.

[0074] Finally, although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for achieving efficient recovery of phosphorus and PHAs from fermented denitrification granular sludge, characterized in that, This method employs a device that utilizes fermentation-based denitrification and phosphorus removal granular sludge to achieve efficient recovery of phosphorus and PHAs, and includes the following steps: I. Cultivation of fermented denitrification phosphorus removal granular sludge: 1) Add activated sludge from the wastewater treatment plant to the granular sludge reactor (3), and control the sludge concentration at 2000 mg / L-8000 mg / L; 2) Start the first influent pump (3.2) to pump influent of volume V1 containing recalcitrant carbon source, ammonia nitrogen and phosphate into the granular sludge reactor (3), and control V1 to be 40%-80% of the effective volume V of the reactor; 3) Control the settling time to be greater than 1 hour, start the first drainage pump (3.5), and pump the supernatant containing phosphate and ammonia nitrogen with a volume of V2 into the phosphorus and ammonia nitrogen outlet tank (5), and control V2 to be 30%-90% of V1; 4) Start the first agitator (3.1), and stop agitating when the sewage and sludge are fully mixed; 5) Control the sedimentation time to be less than 20 minutes, start the first sludge discharge pump (3.4), and discharge the fermentation denitrification phosphorus removal granular sludge with a volume of V3 into the PHAs recovery tank (4), where V3 is the difference between V1 and V2; 6) Start the second inlet pump (3.3) to pump a volume of V4 of nitrate nitrogen inlet water into the granular sludge reactor (3) and control the molar ratio of nitrate nitrogen to phosphate in the granular sludge reactor (3) to be greater than 1.5; 7) Start the first stirrer (3.1), and stop stirring when the nitrate concentration drops to 0 mg / L; 8) Control the sedimentation time to be greater than 10 minutes, start the first drainage pump (3.5), and pump the supernatant with a volume of V4 into the phosphorus and ammonia nitrogen outlet tank (5). 9) Repeat steps 2-8 until the proportion of granular sludge with a particle size greater than 200μm in the mixed sludge is greater than 30%, and control the settling time in step 5 to less than 10min. 10) Repeat steps 2-8 until the proportion of granular sludge with a particle size greater than 200 μm is greater than 50% of the mixed sludge, the molar ratio of phosphate to ammonia nitrogen in the anaerobic granular sludge reactor (3) is greater than 1.0, and the pH value in the anoxic granular sludge reactor (3) is greater than 8.

5. This indicates that the cultivation of fermented denitrification phosphorus removal granular sludge has finally been achieved. II. String of guano recycling: 1) Start the third inlet pump (7.1) to pump ammonia nitrogen and phosphate inlet water with a volume of V5 into the struvite reactor (7), where V5 is the sum of V2 and V4; 2) Start the fourth inlet pump (7.2) to pump the magnesium solution into the struvite reactor (7) and control the molar ratio of magnesium ions to phosphate ions to be 1.0; 3) Start the second stirrer (7.3) and the third stirrer (7.4), and stop stirring when the phosphate concentration drops to 0 mg / L; 4) Control the sedimentation time to be greater than 10 minutes, start the second drainage pump (7.7), and discharge the effluent into the effluent tank (9). 5) Start the second sludge pump (7.6) to discharge the struvite sediment into the phosphorus recovery tank (8), and finally realize the recovery of phosphorus resources in the form of struvite.

2. The method for achieving efficient recovery of phosphorus and PHAs from fermented denitrification granular sludge according to claim 1, characterized in that, The device for efficient recovery of phosphorus and PHAs from fermented denitrification granular sludge includes, in sequence, a recalcitrant carbon source, ammonia nitrogen, and phosphate inlet tank (1), a nitrate nitrogen inlet tank (2), a granular sludge reactor (3), a PHAs recovery tank (4), a phosphorus and ammonia nitrogen outlet tank (5), a magnesium solution inlet tank (6), a struvite reactor (7), a phosphorus recovery tank (8), an outlet tank (9), and an online monitoring and control system (10); wherein the recalcitrant carbon source, ammonia nitrogen, and phosphate inlet tank (1) is connected to the granular sludge reactor (3) via a first inlet pump (3.2); the nitrate nitrogen inlet tank (2) is connected to the granular sludge reactor (3) via a second inlet pump (3.3); the PHAs recovery tank (4) is connected to the granular sludge reactor (3) via a first sludge discharge pump (3.4); and the phosphorus and ammonia nitrogen outlet tank (5) is connected to the granular sludge reactor (3) via a first sludge discharge pump (3.4). A water pump (3.5) is connected to the granular sludge reactor (3); a phosphorus and ammonia nitrogen effluent tank (5) is connected to the struvite reactor (7) via a third influent pump (7.1); a magnesium solution influent tank (6) is connected to the struvite reactor (7) via a fourth influent pump (7.2); a phosphorus recovery tank (8) is connected to the struvite reactor (7) via a second sludge discharge pump (7.6); an effluent tank (9) is connected to the struvite reactor (7) via a second drainage pump (7.7); the granular sludge reactor (3) is connected to the online monitoring and control system (10) via a first phosphate concentration sensor (3.6), a nitrate concentration sensor (3.7), a pH sensor (3.8), and an ammonia nitrogen concentration sensor (3.9); the struvite reactor (7) is connected to the online monitoring and control system (10) via a second phosphate concentration sensor (7.5); The inlet tank (1) for the recalcitrant carbon source, ammonia nitrogen and phosphate is equipped with a first overflow pipe (1.1) and a first vent valve (1.2). The nitrate inlet tank (2) is equipped with a second overflow pipe (2.1) and a second vent valve (2.2); The granular sludge reactor (3) is equipped with a first agitator (3.1), a first inlet pump (3.2), a second inlet pump (3.3), a first sludge discharge pump (3.4), a first drain pump (3.5), a first phosphate concentration sensor (3.6), a nitrate concentration sensor (3.7), a pH sensor (3.8), and an ammonia nitrogen concentration sensor (3.9). The PHAs recycling bin (4) is equipped with a third overflow pipe (4.1) and a third vent valve (4.2). The phosphorus and ammonia nitrogen outlet tank (5) is equipped with a fourth overflow pipe (5.1) and a fourth vent valve (5.2); The magnesium solution inlet tank (6) is equipped with a fifth overflow pipe (6.1) and a fifth vent valve (6.2). The struvite reactor (7) is equipped with a third inlet pump (7.1), a fourth inlet pump (7.2), a second agitator (7.3), a third agitator (7.4), a second phosphate concentration sensor (7.5), a second sludge discharge pump (7.6), and a second drain pump (7.7). The phosphorus recovery tank (8) is equipped with a sixth overflow pipe (8.1) and a sixth vent valve (8.2); The outlet tank (9) is equipped with a seventh overflow pipe (9.1) and a seventh vent valve (9.2); The online monitoring and control system (10) includes a first inlet pump relay (10.1), a pH sensor relay (10.2), an ammonia nitrogen concentration sensor relay (10.3), a first agitator relay (10.4), a first phosphate concentration sensor relay (10.5), a nitrate concentration sensor relay (10.6), a first sludge discharge pump relay (10.7), a first drainage pump relay (10.8), a second inlet pump relay (10.9), a third inlet pump relay (10.10), a second agitator relay (10.11), a third agitator relay (10.12), a second phosphate concentration sensor relay (10.13), a second sludge discharge pump relay (10.14), a fourth inlet pump relay (10.15), a second drainage pump relay (10.16), an A / D converter interface (10.17), a D / A converter interface (10.18), and a computer (10.19). The online monitoring and control system (10) has the following components: a first inlet pump relay (10.1) connected to the first inlet pump (3.2); a pH sensor relay (10.2) connected to the pH sensor (3.8); an ammonia nitrogen concentration sensor relay (10.3) connected to the ammonia nitrogen concentration sensor (3.9); a first stirrer relay (10.4) connected to the first stirrer (3.1); a first phosphate concentration sensor relay (10.5) connected to the first phosphate concentration sensor (3.6); a nitrate concentration sensor relay (10.6) connected to the nitrate concentration sensor (3.7); a first sludge discharge pump relay (10.7) connected to the first sludge discharge pump (3.4); a first drainage pump relay (10.8) connected to the first drainage pump (3.5); a second inlet pump relay (10.9) connected to the second inlet pump (3.3); and a third inlet pump relay (10.10) connected to the third... The inlet pump (7.1) is connected; the second agitator relay (10.11) is connected to the second agitator (7.3); the third agitator relay (10.12) is connected to the third agitator (7.4); the second phosphate concentration sensor relay (10.13) is connected to the second phosphate concentration sensor (7.5); the second sludge pump relay (10.14) is connected to the second sludge pump (7.6); the fourth inlet pump relay (10.15) is connected to the fourth inlet pump (7.2); the second drain pump relay (10.16) is connected to the second drain pump (7.7); the online monitoring and control system (10) converts analog signals into digital signals and transmits them to the computer (10.19) through the signal converter A / D converter interface (10.17) and cable; the computer (10.19) transmits digital instructions to the online monitoring and control system (10) through the cable and the signal converter D / A converter interface (10.18).

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