Anaerobic reactor for automatically elutriating sludge and rapid sludge granulation method

Abstract

The invention discloses an anaerobic reactor for automatically elutriating sludge in the technical field of anaerobic sewage treatment, which comprises a box body, a water distribution system arranged at the bottom in the box body, a water inlet system connected with the water distribution system, a gas flow guide device arranged in the middle in the box body and used for increasing water quantity, and a three-phase separator arranged at the upper part in the box body, the three-phase separator is connected with a biogas tank; an effluent weir is arranged at the top of the tank body; the gas guiding device comprises a gas collecting hood, and the top of the gas collecting hood is connected with an upwelling pipe; gas enters the upflow pipe through the gas collecting hood, the density difference formed in the rising process of the gas in the gas guiding device serves as power, muddy water below the gas collecting hood is lifted to the position below the three-phase separator, downflow is formed on the periphery of the gas guiding device, and self-circulation starts to be formed with the gas guiding device as the center. The problems that existing sludge granulation is long in time, large in difficulty and high in cost are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of anaerobic sewage treatment, and particularly relates to an anaerobic reactor and a method for rapid granulation of sludge. Background Art

[0002] Anaerobic sewage treatment is an important technical means for sewage treatment. Anaerobic reactors usually have problems such as slow startup, low mass transfer efficiency, and easy sludge washout. Sufficient sludge volume and good mass transfer are the key links for the rapid startup and efficient and stable operation of anaerobic reactors. However, in the actual process of anaerobic sewage treatment, good mass transfer and sufficient sludge volume are contradictory. For example, under high mass transfer conditions, it is easy to cause sludge washout in the anaerobic reactor, and it is difficult to ensure sufficient sludge volume in the anaerobic reactor. Granular sludge has the characteristic of good sedimentation performance. Through the granulation of sludge in the anaerobic reactor, the sludge washout can be effectively reduced, and it becomes possible to retain sufficient sludge even under high mass transfer conditions.

[0003] At present, the granulation of anaerobic sludge is mainly achieved by adding flocculants, crystal nuclei, trace elements and other chemicals into the reactor, and improving measures such as mass transfer between the mud and water and hydraulic shear force. However, the granulation of anaerobic sludge has relatively strict requirements for environmental conditions, and generally has problems such as long time, high difficulty, and high cost. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides an anaerobic reactor for automatically elutriating sludge and a method for rapid granulation of sludge, which solves the problems of long time, high difficulty, and high cost in the existing sludge granulation.

[0005] The object of the present invention is achieved as follows: An anaerobic reactor for automatically elutriating sludge includes a box body. A water distribution system is arranged at the bottom inside the box body, and the water distribution system is connected to the water inlet system. A gas guiding device for lifting the water volume is arranged in the middle of the box body. A three-phase separator is arranged at the upper part inside the box body, and the three-phase separator is connected to a biogas tank. An effluent weir is arranged at the top of the box body; its characteristic lies in that the gas guiding device includes a gas collecting hood, and the top of the gas collecting hood is connected to an upflow pipe; the gas enters the upflow pipe through the gas collecting hood, and uses the density difference formed during the upward movement of the gas in the gas guiding device as the driving force to lift the muddy water below the gas collecting hood to below the three-phase separator, and a downward flow is formed outside the gas guiding device, and a self-circulation starts with the gas guiding device as the center.

[0006] Further, a deflector for introducing gas into the gas collecting hood is also arranged inside the box body.

[0007] Further, deflectors are also arranged inside the box body below the three-phase separator.

[0008] Further, the gas collecting hood is in a trumpet-shaped structure with a larger bottom and a smaller top.

[0009] A method for rapid granulation of sludge, comprising the following steps: Step 1) First, add pre-granulated seed sludge into the anaerobic reactor so that the gas collection hood is submerged below the bottom sludge layer; Step 2) Feed the wastewater to be treated into the anaerobic reactor in a continuous flow manner through the influent system. Start the reactor under high initial load and high-amplitude load increase. As the sewage treatment efficiency of the anaerobic reactor improves, gradually increase the influent load until the design load is reached; Step 3) When the gas production intensity of the anaerobic reactor reaches a certain value, the total amount of mud and water lifted by the gas diversion device is greater than the influent volume. Utilize the lifting effect of the gas diversion device on the mud and water to lift the flocculent sludge and pre-granulated sludge in the sludge layer below the gas diversion device together to below the three-phase separator; Step 4) Utilize the upward water flow formed around and above the three-phase separator to wash out the flocculent sludge with poor settling performance in the lifted sludge from the anaerobic reactor; utilize the downward flow formed around the gas diversion device to retain the pre-granulated sludge with good settling performance in the lifted sludge in the anaerobic reactor; utilize the high mass transfer generated during the self-circulation of the mud and water and the high hydraulic shear force formed during the rapid upward movement of the mud and water to quickly cultivate the retained pre-granulated sludge, realizing the rapid granulation of the anaerobic reactor sludge.

[0010] Further, in Step 1), the extrusion sludge from the sewage treatment plant is soaked in water and intermittently stirred to make seed sludge. The seed sludge is a mixture of flocculent sludge and pre-granulated sludge, and the proportion of pre-granulated sludge is more than 30%; the dosage of the pre-granulated seed sludge is: more than 1 / 4 of the effective volume of the anaerobic reactor.

[0011] Further, in Step 2), the high initial load is: the initial influent load is greater than 0.3 kg COD / (kgVS·d); the gradual increase of the influent load is: when the COD removal rate of the reactor stably reaches more than 80%, the influent load is increased by more than 30%.

[0012] Further, when the gas production intensity remains unchanged, according to the need, by reducing the inner diameter of the upward flow pipe, the mud and water flow velocity in the upward flow pipe is increased, and the total amount of mud and water lifted by the gas diversion device is increased, and vice versa; when the gas production intensity remains unchanged, by lengthening the length or vertical height of the upward flow pipe, the mud and water flow velocity in the upward flow pipe is increased, and the total amount of mud and water lifted by the gas diversion device is increased, and vice versa.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: By adding pre-granulated seed sludge in advance and transforming the traditional anaerobic reactor, on the one hand, the flocculent sludge with poor sedimentation performance is automatically washed out of the anaerobic reactor; on the other hand, the remaining pre-granulated sludge is quickly cultivated into anaerobic granular sludge, realizing the rapid granulation of the sludge in the anaerobic reactor; this invention is of great significance for shortening the start-up time of the anaerobic reactor and its efficient and stable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0015] Figure 1 It is a schematic structural diagram of the anaerobic reactor in the present invention.

[0016] Among them, 1. inlet water system; 2. water distribution system; 3. first guide vane; 4. second guide vane; 5. gas collection hood; 6. upflow pipe; 7. third guide vane; 8. three-phase separator; 9. biogas tank; 10. effluent weir; 11. sludge layer; 12. included angle of the inclined surface of the gas collection hood; 13. reactor; 14. agitator; 15. sludge pre-granulation device. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0018] Embodiment 1 As Figure 1 shown, an anaerobic reactor 13 for automatically washing sludge includes: The box body is provided with a water distribution system 2 at the bottom inside the box body. The water distribution system 2 is connected to the water inlet system 1. A gas diversion device for increasing the water volume is arranged in the middle of the box body. A three-phase separator 8 is arranged at the upper part inside the box body. The three-phase separator 8 is connected to a biogas tank 9. A water outlet weir 10 is arranged at the top of the box body. The gas diversion device includes a gas collection hood 5, and the top of the gas collection hood 5 is connected to an upflow pipe 6. First guide vanes 3 and second guide vanes 4 for guiding gas into the gas collection hood 5 are arranged inside the box body. Third guide vanes 7 are also arranged inside the box body below the three-phase separator 8. The gas collection hood 5 is in the shape of a horn with a larger bottom and a smaller top. The bottom of the reactor 13 is connected to a sludge pre-granulation device 15 through a pipeline, and a stirrer is arranged inside the sludge pre-granulation device 15.

[0019] A gas diversion device is installed between the water distribution system 2 and the three-phase separator 8 of the anaerobic reactor 13.

[0020] The gas diversion device consists of a gas collection hood 5 and an upflow pipe 6. The upflow pipe 6 is vertically connected above the gas collection hood 5.

[0021] The gas collection hood 5 is in a shape that tapers from bottom to top, and its inclined clamping angle is less than 60°, like an inverted funnel.

[0022] Example 2 A method for rapid sludge granulation includes: Soaking the extruded sludge from the sewage treatment plant in water and using the intermittent stirring method to make pre-granulated seed sludge.

[0023] Pre-granulated seed sludge is added into the anaerobic reactor 13, and the dosage of the seed sludge is about 1 / 3 of the effective volume of the reactor 13.

[0024] It should be noted that the pre-granulated seed sludge is a mixture of flocculent sludge and pre-granulated sludge, and the proportion of the pre-granulated sludge is more than 30%. During the operation stage of the reactor 13, the gas collection hood 5 is submerged below the bottom sludge layer 11.

[0025] To ensure a relatively high gas production rate in the initial stage, the anaerobic reactor 13 is started with a continuous flow process under initial high load and high-amplitude load increase.

[0026] As the operation efficiency of the anaerobic reactor 13 improves, when the COD removal rate stably reaches more than 80%, the influent load is increased by more than 30%.

[0027] By increasing the influent load, the gas production intensity of the anaerobic reactor 13 is increased.

[0028] Using the gas guide vanes below the gas collection hood 5, the biogas below the gas collection hood 5 is diverted into the gas diversion device.

[0029] Using the density difference formed during the upward movement of biogas in the gas diversion device as the driving force, the muddy water below the gas collection hood 5 is lifted to below the three-phase separator 8.

[0030] As the gas production intensity increases, the amount of muddy water lifted by the gas diversion device also increases accordingly.

[0031] When the gas production intensity reaches a certain value, the total amount of muddy water lifted by the gas diversion device is greater than the water inflow. The muddy water in excess of the water inflow forms a downward flow around the gas diversion device and begins to form a self-circulation centered on the gas diversion device.

[0032] Using the lifting effect of the gas diversion device on the muddy water, the flocculent sludge and pre-granulated sludge below the gas collection hood 5 are lifted to below the three-phase separator 8.

[0033] Using the upward water flow formed above the three-phase separator 8, the flocculent sludge with poor sedimentation performance in the lifted sludge is washed out of the anaerobic reactor 13.

[0034] Using the downward flow formed around the gas diversion device, the pre-granulated sludge with good sedimentation performance in the lifted sludge is retained in the anaerobic reactor 13.

[0035] Using the high mass transfer formed during the self-circulation of the muddy water and the high hydraulic shear force formed during the rapid upward movement of the muddy water in the upward flow pipe 6, the retained pre-granulated sludge is rapidly converted or cultivated into anaerobic granular sludge, realizing the rapid granulation of the sludge in the anaerobic reactor 13.

[0036] Furthermore, when the gas production intensity remains unchanged, by reducing the inner diameter of the upward flow pipe 6, the flow velocity of the muddy water in the upward flow pipe 6 is increased, and the total amount of muddy water lifted by the gas diversion device is increased, and vice versa.

[0037] Furthermore, when the gas production intensity remains unchanged, by increasing the vertical height, the flow velocity of the muddy water in the upward flow pipe 6 is increased, and the total amount of muddy water lifted by the gas diversion device is increased, and vice versa.

[0038] Furthermore, when the upward flow velocity of the muddy water in the upward flow pipe 6 is relatively high and the total amount of muddy water lifted by the gas diversion device is more than 5 times the water inflow, the sludge granulation time of the anaerobic reactor 13 can be shortened to within 15 days.

[0039] Furthermore, by adding pre-granulated seed sludge, on the one hand, the MLSS and sedimentation performance of the sludge in the anaerobic reactor 13 are improved; on the other hand, it provides the prototype, crystal nucleus, carrier, etc. of granular sludge for the rapid granulation of the reactor 13 sludge, shortening the cultivation time of granular sludge.

[0040] To improve the efficiency of automatic sludge washing and pre-granulation of the anaerobic reactor 13, it is recommended that the height-diameter ratio of the reactor 13 be controlled above 4.

[0041] The description of the above embodiments is only used to help understand the method and its core idea of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. An anaerobic reactor for automatic sludge washing, comprising a box, a water distribution system (2) is arranged at the bottom of the box, the water distribution system (2) is connected to the water inlet system (1), a gas diversion device for increasing the water volume is arranged in the middle of the box, a three-phase separator (8) is arranged at the upper part of the box, the three-phase separator (8) is connected to the biogas tank (9), a water outlet weir (10) is arranged at the top of the box, and the bottom of the reactor (13) is connected to the sludge pre-granulation device (15) through a pipeline; characterized in that: The gas flow guiding device comprises a gas collecting hood (5), the top of which is connected to an ascending flow pipe (6); the gas enters the ascending flow pipe (6) through the gas collecting hood (5), and uses the density difference formed in the process of gas ascending in the gas flow guiding device as a driving force to lift the muddy water below the gas collecting hood (5) to below the three-phase separator (8), and forms a descending flow around the gas flow guiding device, and starts to form a self-circulation with the gas flow guiding device as the center.

2. The anaerobic reactor for automatic sludge washing according to claim 1, characterized in that: The box body is also provided with a guide plate for guiding the gas into the gas collecting hood (5).

3. An anaerobic reactor for automatic sludge washing according to claim 1 or 2, characterized in that: A guide vane is also provided in the box below the three-phase separator (8).

4. An anaerobic reactor for automatic sludge washing according to claim 1 or 2, characterized in that: The gas collecting hood (5) is a trumpet-shaped structure that is larger at the bottom and larger at the top.

5. A method for rapid granulation of sludge, using an anaerobic reactor for automatic sludge washing according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1) firstly add pre-granulated seed sludge into the anaerobic reactor (13) so that the gas collecting hood (5) is submerged below the bottom mud layer (11); Step 2) introducing the wastewater to be treated into the anaerobic reactor (13) in a continuous flow manner through the water inlet system (1), starting the reactor (13) under a high initial load and a high amplitude load increase, and gradually increasing the water inlet load as the wastewater treatment efficiency of the anaerobic reactor (13) increases until the design load is reached; Step 3) When the gas production intensity of the anaerobic reactor (13) reaches a certain value, the total amount of mud and water lifted by the gas diversion device is greater than the water intake, and the gas diversion device is used to lift the mud and water, so that the flocculent sludge and pre-granulated sludge in the mud layer (11) below the gas diversion device are lifted together to the bottom of the three-phase separator (8); Step 4) utilizing the rising water flow formed at the periphery and above the three-phase separator (8) to wash out the flocculent sludge with poor settling performance in the lifted sludge from the anaerobic reactor (13); utilizing the descending flow formed at the periphery of the gas guide device to retain the pre-granulated sludge with good settling performance in the lifted sludge in the anaerobic reactor (13); utilizing the high mass transfer generated during the self-circulation of mud and water and the high hydraulic shear force generated during the rapid rise of mud and water to rapidly cultivate the retained pre-granulated sludge, thereby realizing the rapid granulation of the anaerobic reactor sludge.

6. A method for rapid sludge granulation according to claim 5, characterized in that: In step 1), the squeezed sludge from the sewage treatment plant is soaked in water and stirred intermittently to prepare seed sludge, wherein the seed sludge is a mixture of flocculent sludge and pre-granulated sludge, wherein the pre-granulated sludge accounts for more than 30%; The dosage of the pre-granulated seed sludge is: more than 1 / 4 of the effective volume of the anaerobic reactor (13).

7. A method for rapid sludge granulation according to claim 5 or 6, characterized in that: Step 2) The medium-high initial load is: the initial influent load is greater than 0.3 kg COD / (kgVS.d); the influent load is gradually increased: when the COD removal rate of the reactor (13) stably reaches more than 80%, the influent load is increased by more than 30%.

8. A method for rapid sludge granulation according to claim 5 or 6, characterized in that: When the gas production intensity remains unchanged, the mud and water flow rate in the ascending flow pipe (6) is increased by reducing the inner diameter of the ascending flow pipe (6) as needed, thereby increasing the total amount of mud and water lifted by the gas diversion device, and vice versa; when the gas production intensity remains unchanged, the mud and water flow rate in the ascending flow pipe (6) is increased by lengthening the length or vertical height of the ascending flow pipe (6), thereby increasing the total amount of mud and water lifted by the gas diversion device, and vice versa.

9. A method for rapid sludge granulation according to claim 8, characterized in that: The maximum inner diameter of the ascending flow pipe (6) is controlled to be less than 100 mm; and the total amount of muddy water lifted by the gas diversion device is controlled to be more than 5 times the amount of water intake.

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