Struvite phosphorus removal device for anaerobic effluent

Abstract

The utility model relates to a struvite dephosphorization device for anaerobic effluent, which mainly solves the technical problems of high moisture content, more impurities and the like of products of the existing dephosphorization device. The device comprises a fluidized bed reactor with a cylindrical structure, and the fluidized bed reactor sequentially comprises a collecting area, a reaction area and a settling area from bottom to top. The lower part of the reaction area is provided with a water inlet, a medicament inlet and a reflux inlet which are respectively connected with a water inlet pump, a medicament pump and a reflux pump; a reaction sleeve is arranged at the middle lower part of the reaction area; an aeration head is arranged in the reaction sleeve. And the diameter of the upper barrel of the reaction area is gradually increased and transited to the settling area. A settlement sleeve is also arranged in the settlement area. And the bottom of the sedimentation tank is connected with a reflux pump and a reflux inlet through a pipeline. A gas inlet is formed in the top of the settlement area and connected with an aeration head through a gas pipeline; the gas pipeline is connected with a flowmeter and a gas pump. The bottom of the collecting area is connected with a sludge pump through a pipeline.

Description

Technical Field

[0001] This utility model relates to a phosphorus removal device for phosphate fertilizer wastewater, and more particularly to a struvite phosphorus removal device for anaerobic effluent. Background Technology

[0002] Struvite (MAP) is a white crystalline solid with the molecular formula MgNH4PO4·6H2O. It is a high-quality nitrogen and phosphorus fertilizer. In wastewater treatment, if a certain concentration of NH4 is present... + PO4 3- and Mg 2+ Under certain pH and mixing energy conditions, struvite precipitates can spontaneously form due to ions. The reaction formula is as follows:

[0003] Mg 2+ + NH4 + + PO4 3- +6H2O ® MgNH4PO4·6H2O↓

[0004] Anaerobic fermentation liquid from pig manure, kitchen waste, etc. contains a large amount of NH4. + PO4 3- In a mechanically stirred reaction tank, NaOH and MgCl2 are added to generate struvite precipitate, which is then separated in a settling tank. This type of reactor produces struvite crystals with small particles and a high water content in the precipitate, requiring further dehydration. Furthermore, it contains many impurities, resulting in low product recycling value. Utility Model Content

[0005] The purpose of this invention is to provide a struvite dephosphorization device for anaerobic effluent, which mainly solves the technical problems of high water content and many impurities in the products of existing dephosphorization devices.

[0006] The technical solution of this utility model is as follows: a struvite phosphorus removal device for anaerobic effluent, comprising a fluidized bed reactor. The main body of the fluidized bed reactor is a cylindrical structure, consisting of, from bottom to top: a collection zone, a reaction zone, and a settling zone. The lower part of the reaction zone is equipped with an inlet, a reagent inlet, and a return outlet, which are respectively connected to an inlet pump, a reagent pump, and a return pump. A reaction sleeve is installed in the lower middle part of the reaction zone, and an aeration head is installed inside the reaction sleeve. The diameter of the upper part of the cylindrical body gradually increases, transitioning to the settling zone. A settling sleeve is also provided in the settling zone. An outlet is provided at the upper part of the settling zone, connecting to a sedimentation tank. The bottom of the sedimentation tank is connected to a return pump and a return outlet via pipelines. A gas inlet is provided at the top of the settling zone, connected to an aeration head via a gas pipeline. The gas pipeline is connected to a flow meter and an air pump. The bottom of the collection zone is connected to a sludge pump via pipelines.

[0007] A pH probe is installed inside the fluidized bed reactor to continuously monitor the pH value of the wastewater. The pH of the fluidized bed reactor is automatically adjusted by adding alkali.

[0008] The beneficial effects of this utility model are:

[0009] 1. Aeration and stripping raise the pH of the anaerobic effluent from 7.2 to 8.5, achieving the suitable pH range for struvite formation without the need for alkali addition, thus saving on chemical costs.

[0010] 2. Under aeration conditions, the total phosphorus content contains polyphosphates and metaphosphates (PO3). - phosphite PO3 3- When converted to orthophosphate PO4 3- The struvite reaction occurs, which improves the removal efficiency of total phosphorus.

[0011] 3. The air-lifting effect of the reaction zone sleeve increases the turbulence intensity in the reaction zone, making it more suitable for the generation of struvite crystal particles.

[0012] 4. An external sedimentation tank is added to the effluent, and the microcrystals after sedimentation are returned, which improves the removal rate of total phosphorus.

[0013] 5. At the same time, microcrystals, as seed crystals, can improve the particle size and purity of the crystallization product, making it easier to generate large particles and resulting in better granulation effect. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model.

[0015] In the diagram: 1-fluidized bed reactor, 101-collection zone, 102-reaction zone, 103-sedimentation zone, 104-reaction sleeve, 105-sedimentation sleeve, 2-inlet pump, 3-chemical pump, 4-return pump, 5-aeration head, 6-flow meter, 7-air pump, 8-sedimentation tank, 9-pH probe, 10-sludge pump. Detailed Implementation

[0016] Reference Figure 1A struvite phosphorus removal device for anaerobic effluent includes a fluidized bed reactor 1. The main body of the fluidized bed reactor is a cylindrical structure with a height of 200 mm, consisting of, from bottom to top: a collection zone 101, a reaction zone 102, and a settling zone 103. The reaction zone has a diameter of 150 mm and a height of 1000 mm, while the settling zone has a diameter of 350 mm. The lower part of the reaction zone has an inlet, a reagent inlet, and a return outlet, which are connected to an inlet pump 2, a reagent pump 3, and a return pump 4, respectively. A reaction sleeve 104 is installed in the lower middle part of the reaction zone, and an aeration head 5 is installed inside the reaction sleeve 104. The diameter of the upper part of the cylindrical structure of the reaction zone 102 gradually increases, transitioning to the settling zone 103. The settling zone 103 also has a settling sleeve 105. The upper part of the settling zone 103 has an outlet connected to a sedimentation tank 8, and the bottom of the sedimentation tank 8 is connected to the return pump 4 and a return outlet via pipelines. The settling zone 103 has a gas inlet at the top, which is connected to an aeration head 5 via a gas pipeline. The gas pipeline is also connected to a flow meter 6 and an air pump 7. The collection zone 101 has a sludge pump 10 connected to its bottom via a pipeline.

[0017] A pH probe is installed inside the fluidized bed reactor to continuously monitor the pH value of the wastewater. The pH of the fluidized bed reactor is automatically adjusted by adding alkali.

[0018] When using, the parameters are set as follows: water inlet flow rate 30L / h, air inlet flow rate 15L / min, and PO4 inlet... 3- When the concentration of -P is 250 mg / L and the concentration of NH3-N is 500 mg / L, Mg 2+ The molar ratio of Mg is 2+ When P=1.1.

[0019] Wastewater enters the bottom of the reactor via an influent pump, while an air pump injects air into the reactor to provide stirring energy and simultaneously strips CO2 from the anaerobic effluent. This stripping action raises the pH of the wastewater, reducing the amount of alkali required. The air flow rate can be measured using a flow meter. Inside the reaction zone sleeve, water and gas flow upwards, while outside the sleeve, water flows downwards, creating a circulating flow.

[0020] In the reaction zone, after the wastewater and reagents are mixed, crystal ions aggregate to form nuclei and continue to grow, forming crystals. Struvite crystals are distributed throughout the reaction zone according to their particle size. Crystal particles that have grown to a certain size are collected at the bottom of the reactor and discharged via a sludge pump.

[0021] The upper part of the reactor is a settling zone. To prevent rising gas from interfering with the settling zone, a settling sleeve is installed. Outside the settling sleeve, smaller crystal particles settle and flow back to the reaction zone. The reactor effluent is discharged after settling in an external settling tank 8. The tiny crystals at the bottom of the external settling tank 8 are returned to the fluidized bed reactor 1 via a reflux pump 4.

[0022] Tests showed that the removal rate of phosphorus (P) reached 90%. 85% of the struvite particles were in the 2.0-2.5 mm range.

Claims

1. A struvite phosphorus removal device for anaerobic effluent, characterized in that: The fluidized bed reactor comprises a cylinder structure from bottom to top, which is sequentially composed of a collection zone, a reaction zone and a sedimentation zone; the lower part of the reaction zone is provided with a water inlet, a medicament inlet and a reflux inlet, which are respectively connected with a water pump, a medicament pump and a reflux pump; a reaction sleeve is arranged in the middle and lower part of the reaction zone, and an aeration head is arranged in the reaction sleeve; a sedimentation sleeve is arranged in the sedimentation zone; the upper part of the sedimentation zone is provided with a water outlet connected with a sedimentation tank, and the bottom of the sedimentation tank is connected with the reflux pump and the reflux inlet through pipelines; the top of the sedimentation zone is provided with a gas inlet connected with the aeration head through a gas pipeline, and the gas pipeline is connected with a gas pump; and the bottom of the collection zone is connected with a sludge pump through a pipeline.

2. The struvite-based phosphorus removal device for anaerobic effluent according to claim 1, characterized in that: The diameter of the upper cylinder of the reaction zone is gradually enlarged and transitions to the sedimentation zone.

3. The struvite-based phosphorus removal device for anaerobic effluent according to claim 1, characterized in that: A flow meter is arranged on the gas pipeline.

4. The struvite-based phosphorus removal device for anaerobic effluent according to claim 1, characterized in that: A pH probe is arranged in the fluidized bed reactor.

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