Iron-carbon coupling mesh interception and drying return of sludge granulation device and method

Abstract

This invention belongs to the field of wastewater biological treatment technology, and relates to a sludge granulation device and method using iron-carbon coupled mesh interception and drying-backfilling. The device includes a cylinder, an inlet / outlet system, a variable-speed stirring system, an automatic control system, and a composite packing system. The inlet / outlet system includes an inlet and an overflow port at the top of the cylinder, and an outlet at the bottom of the cylinder. The stirring system includes a variable-frequency motor for sludge stirring and a stirring rod for supporting the packing material. The automatic control system includes a controller for timed adjustment of the stirrer speed, direction, running time, and valves of the inlet / outlet system. The composite packing system includes a plastic ball packing cover fixed to the stirring rod and internally filled with mesh packing and iron-carbon packing. This invention has a simple structure and can achieve automated control operation. By intercepting lightweight activated sludge through mesh, subjecting it to iron-carbon crystal nucleation stress, and drying and agglomerating it, aggregates of different particle sizes and densities are formed and returned to the biochemical reaction tank, promoting the formation of granular sludge.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a sludge granulation device and method for iron-carbon coupled mesh interception and drying and refeeding. Background Technology

[0002] Aerobic granular sludge technology is a novel and promising biological wastewater treatment technology. Aerobic granular sludge possesses advantages such as excellent settling performance, dense structure, high biomass, tolerance to high organic loads and toxic substances, and the ability to achieve simultaneous nitrification and denitrification. The formation of aerobic granular sludge often depends on multiple factors, such as selectivity, culture medium type and organic load, hydraulic shear force, reactor configuration, inoculum sludge, metal ions, and aggregates. The "nucleus theory" is currently one of the most important theories regarding granular sludge formation.

[0003] It is reported that there are currently over 100 wastewater treatment plants worldwide using aerobic granular sludge technology, and there are also reports of its application in Zhejiang Province. However, these wastewater treatment plants generally have high COD levels and all use sequencing batch reactors (SBRs). For some low-concentration municipal wastewater treatment plants or rural wastewater treatment facilities, especially continuous flow wastewater treatment processes, the formation and stable operation of aerobic granular sludge remain challenging. To overcome this bottleneck, there is an urgent need to develop effective equipment and strategies to ensure the formation and stability of granular sludge. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a sludge granulation device and method involving iron-carbon coupled mesh interception and drying refeeding. The activated sludge rapid granulation equipment has a simple structure and can achieve automated control operation. Through mesh interception of light activated sludge, iron-carbon crystal nucleus stress, and drying and agglomeration, aggregates are formed and refeeded into the biochemical reaction tank, promoting the formation of aerobic granular sludge and enhancing pollutant removal.

[0005] This invention provides a sludge granulation device with iron-carbon coupled mesh interception and drying refeeding, comprising: a cylinder, a feeding and discharging system, a variable speed stirring system, an automatic control system, and a composite packing system. The feeding and discharging system includes a feed inlet and an overflow outlet at the top of the cylinder and a discharge outlet at the bottom of the cylinder; the stirring system includes a variable frequency motor for sludge stirring and a stirring rod for supporting the packing; the automatic control system includes a controller for timed adjustment of the stirrer speed, direction, running time, and valves of the feeding and discharging system; the composite packing system includes a plastic ball packing cover fixed to the stirring rod and internally filled with mesh packing and iron-carbon packing.

[0006] Preferably, the mesh packing material is polyurethane biological packing material, and the iron-carbon packing material is iron shavings packing material. The iron shavings are wrapped in the polyurethane biological packing material and fixed with a plastic ball packing cover. The dense mesh structure of the polyurethane biological packing material can effectively trap lightweight flocs, and the iron shavings wrapped inside the polyurethane can generate [H], ·OH, and Fe through micro-electrolysis in water. 2+ Fe 3+ It contains beneficial substances such as Fe minerals that promote granulation, while stimulating microorganisms to secrete EPS, and promoting microbial aggregation to form aggregates by bridging with EPS.

[0007] Preferably, the packing system is centered on the stirring rod, and the composite packing is connected by cable ties to form a cylindrical packing module according to the diameter and height of the cylinder. A distance of 5 to 10 cm is reserved between the packing module and the cylinder.

[0008] In addition, the present invention provides a sludge granulation treatment method using iron-carbon coupled mesh interception and drying and refeeding, wherein the method involves rapidly granulating activated sludge using any of the aforementioned iron-carbon coupled mesh interception and drying and refeeding sludge granulation devices.

[0009] Preferably, the sludge granulation treatment method using iron-carbon coupled mesh interception and drying refeeding includes the following steps:

[0010] (1) Slow stirring and sludge interception: According to the location of equipment installation, pump the activated sludge from the biological tank or the light sludge selected by the continuous flow dual-zone sedimentation tank or sequencing batch reactor, and slowly stir it forward at a speed of 5-10 r / min while feeding the sludge.

[0011] (2) Slow drainage: After continuously feeding mud for a period of time, stop feeding mud and stop stirring at the same time. Control the bottom discharge valve to drain the mud slowly.

[0012] (3) Sludge drying: After the sludge is discharged, let it stand for a period of time, and then slowly stir it in the forward direction at a speed of 3-5 r / min to dry the sludge;

[0013] (4) Reverse rapid stirring separation: Sludge is continuously fed from the feed inlet again. When the sludge overflows from the overflow outlet of the device, it is rapidly stirred in reverse at a speed of 120-150 r / min. The dried sludge aggregates are separated by centrifugal force, and the aggregates produced are returned to the biological treatment tank.

[0014] (5) Taking steps (1) to (4) as one cycle, the automatic operation of the device is achieved through the regulation of the automatic control system.

[0015] As a further preferred option, the sludge feeding time in step (1) can be 10 to 14 hours depending on the sludge concentration. If the sludge concentration is greater than 1000 mg / L, the sludge feeding time can be appropriately shortened when the sludge concentration is too high.

[0016] As a further preferred option, the sludge removal time in step (2) is controlled at 30 to 60 minutes;

[0017] As a further preferred option, the drying time in step (3) is 8 to 12 hours depending on the temperature at the site;

[0018] As a further preferred option, the rapid stirring time in step (4) is 1 hour.

[0019] The principle of this invention lies in utilizing the dense mesh structure of the mesh packing to trap lightweight activated sludge. During sludge feeding, the slow stirring of the mixer and the continuous extrusion of the water flow cause sufficient collisions within the polyurethane mesh pores, promoting sludge aggregation. Furthermore, the lightweight sludge, with filamentous bacteria as the framework and EPS as the binder, forms aggregates of different shapes and sizes within the pores. The addition of iron and carbon can further promote the formation of these aggregates. The micro-electrolysis process of iron shavings encased within the polyurethane can generate [H], ·OH, and Fe. 2+ Fe 3+ And iron-containing minerals and other substances that promote granulation: Fe 2 + Fe 3+ Its byproducts can serve as nuclei for microbial attachment and growth, leading to rapid formation of granular sludge; ·OH can act as a driving force for the formation and stable operation of aerobic granular sludge; Fe 2+ and Fe 3+ As a metallic cation, it carries a positive charge, while the cell surface carries a negative charge. It aggregates through charge neutralization and stimulates microorganisms to secrete EPS. The sludge drying and refeeding can quickly form aggregates and promote the formation of granular sludge. After natural drying, activated sludge will secrete a large amount of EPS, which will cause the sludge to flocculate and form aggregates. The formed aggregates are fed back into the reactor. Some of the larger aggregates gradually form compact granular sludge under the action of hydraulic shear force and aeration, while the smaller aggregates can act as the core or carrier of granular sludge to induce microbial attachment and growth, and assist in the rapid granulation of sludge.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention equips the equipment with technologies such as iron-carbon, mesh interception, and drying and refeeding to promote the granulation of activated sludge. It develops a sludge granulation device suitable for low-concentration wastewater. By selectively screening light sludge from a continuous flow dual-zone sedimentation tank or a sequencing batch reactor, or activated sludge from a biological treatment tank, the device performs mesh interception, iron-carbon crystal nucleation stress, and drying and agglomeration to form aggregates that are then fed back into the biological treatment tank. This promotes the formation of aerobic granular sludge and enhances the removal of pollutants. At the same time, the device is automated through an automatic control system.

[0022] Attached Figures and Tables

[0023] To more clearly illustrate the embodiments of the present invention, the drawings will be described below:

[0024] Figure 1 This is a schematic diagram of the overall structure of a sludge granulation device with iron-carbon coupled mesh interception and drying refeeding, as shown in the embodiment.

[0025] Figure 2 A schematic diagram of the iron-carbon-mesh composite filler and its arrangement.

[0026] Figure 3 The images show a comparison of microscope photographs of the influent mud (a) and the produced aggregate (b) in the example.

[0027] Explanation of reference numerals in the attached drawings: 1. Cylinder body; 2. Inlet; 3. Overflow port; 4. Outlet; 5. Variable frequency motor; 6. Stirring rod; 7. Controller; 8. Iron-carbon-polyurethane composite packing; 9. Plastic ball packing cover; 10. Iron shavings packing; 11. Polyurethane packing. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Those skilled in the art will be able to implement the present invention practically based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0029] Example 1

[0030] Reference Figures 1-2 The sludge granulation device of iron-carbon coupled mesh interception and drying refeeding in this embodiment includes: a cylinder 1, a feeding and discharging system, a variable speed stirring system, a packing system and an automatic control system.

[0031] The feeding and discharging system includes a feed inlet 2 and an overflow outlet 3 located at the top of the cylinder 1, and a discharge outlet 4 located at the bottom of the cylinder; the stirring system includes a variable speed, forward and reverse variable frequency motor 5 for stirring the sludge and a stirring rod 6 for carrying the packing material; the automatic control system includes a controller 7 for automatically adjusting the speed, direction, and running time of the mixer and the valves of the feeding and discharging system, and realizes the automated operation of the equipment by adjusting the valves of the feed inlet 2 and the discharge outlet 4 and the running time and speed of the variable frequency motor 5 at timed intervals; the packing system includes a plastic ball packing cover 9 fixed on the stirring rod and polyurethane packing 10 and iron shavings packing 11 filled inside. The plastic ball packing cover 9 has a diameter of 10cm, and each plastic ball packing cover 9 contains 8-10 polyurethane biological packing materials 10 with a specification of 2.5*2.5*2.5cm and 10-15g iron shavings packing 11. The polyurethane packing material 10 wraps the iron shavings packing 11 and is then fixed by the plastic ball packing cover 9 to form an iron-carbon-polyurethane composite packing material 8. The composite packing material 8 is fixed to the stirring rod 6 layer by layer with cable ties, 22 pieces per layer, for a total of 5 layers. The packing material is tightly connected, which is beneficial for retaining light activated sludge.

[0032] This embodiment of a sludge granulation treatment method using iron-carbon coupled mesh interception and drying refeeding includes the following steps:

[0033] (1) Slow stirring and sludge interception: Activated sludge from the biochemical reaction tank in the 20t / d oxidation ditch device is continuously pumped into cylinder 1 through inlet 2. The sludge concentration in the biochemical reaction tank is 4000mg / L. The flow rate and outlet valve 4 are controlled to submerge the packing material with sludge. Sludge from overflow outlet 3 and outlet 4 is discharged back into the biochemical reaction tank. While the sludge is being fed in, slow forward stirring is performed at a speed of 5-10r / min for 10 hours.

[0034] (2) Slow drainage: After continuously feeding mud for 10 hours, stop feeding mud and stop stirring at the same time. Control the discharge port valve 4 to allow it to drain slowly for 1 hour.

[0035] (3) Sludge drying: After the slow drainage is completed, let it stand for 30 minutes, and then slowly stir it in the forward direction at a speed of 3-5 r / min for 10 hours to dry the sludge.

[0036] (4) Reverse rapid stirring separation: Sludge is continuously fed again from the feed inlet 2. When the sludge overflows from the overflow outlet 3 of the device, the variable frequency motor 5 is started at a speed of 120-150 r / min for rapid reverse stirring. The dried sludge aggregates are separated by centrifugal force. The produced aggregates are returned to the biological treatment tank along with the sludge.

[0037] Light sludge a selected by pressure screening in a dual-zone sedimentation tank and aggregate b produced in the example are shown below. Figure 3As shown, the light sludge, after being intercepted by mesh, subjected to iron-carbon crystal nuclei stress, and dried and aggregated, forms aggregates with different particle sizes and densities. The particle size of the aggregates is mainly distributed between 50 and 200 μm. When returned to the biological treatment tank, it can effectively accelerate the formation of granular sludge.

[0038] Example 2

[0039] The aggregate yield of the sludge granulation device described in section 1, which involves iron-carbon coupled mesh interception and drying refeeding, was determined using the following specific test method:

[0040] Light sludge selected from the dual-zone sedimentation tank in the 20t / d oxidation ditch unit is pumped into cylinder 1 through inlet 2. Sludge feeding is stopped once the packing module is submerged, at which point the initial sludge concentration in the cylinder is measured to be 1252 mg / L. The sludge concentration in the cylinder is then measured every 2 hours. The amount of sludge retained by the packing module is calculated based on the concentration difference and time data. This retained sludge is dried and returned to the reactor as aggregates. Therefore, the sludge aggregate yield is defined as the mass of aggregates produced per unit sludge volume per unit time. Calculations show that the sludge concentrations in the cylinder at 2, 4, 6, and 8 hours are 1214, 1139, 1029, and 1010 mg / L, respectively, resulting in a sludge aggregate yield of 12.3 g / m³. 3 ·h.

Claims

1. A method for granulating sludge using a sludge granulation device with iron-carbon coupled mesh packing for interception, drying, and refeeding, characterized in that... The sludge granulation device includes: a cylinder (1), a feeding and discharging system, a variable speed stirring system, an automatic control system, and a composite packing system; the feeding and discharging system includes a feed inlet (2) and an overflow outlet (3) located at the top of the cylinder (1) and a discharge outlet (4) located at the bottom of the cylinder; the variable speed stirring system includes a variable frequency motor (5) for sludge stirring and a stirring rod (6) for carrying the packing; the automatic control system includes a controller (7) for timed adjustment of the stirring rod (6) speed, direction, and running time, and for controlling the valves of the feeding and discharging system; the composite packing system includes a plastic ball packing cover (9) fixed on the stirring rod and iron-carbon packing (10) and mesh packing (11) filled inside it. The treatment method rapidly granulates light activated sludge from continuous flow dual-zone sedimentation tanks, sequencing batch reactors, or biological treatment tanks obtained through selective pressure screening. Specifically, it includes the following steps: (1) Slow stirring and sludge interception: According to the location of the device installation, the activated sludge from the biological tank or the light activated sludge selected by the continuous flow dual-zone sedimentation tank or sequencing batch reactor is pumped into the sludge granulation device. At the same time as the sludge is fed, it is slowly stirred in the forward direction at a speed of 5~10r / min. (2) Slow drainage: After continuously feeding mud for a period of time, stop feeding mud and stop stirring at the same time. Control the bottom discharge valve to drain the mud slowly. (3) Sludge drying: After drainage is completed, let it stand for a period of time, and then slowly stir it in the forward direction at a speed of 3~5 r / min to dry the sludge; (4) Reverse rapid stirring separation: Sludge is continuously fed from the feed inlet again. When the sludge overflows from the overflow port of the device, it is rapidly stirred in reverse at a speed of 120~150 r / min. The dried sludge aggregates are separated by centrifugal force, and the aggregates produced are returned to the biological treatment tank along with the sludge. (5) Taking steps (1) to (4) as a cycle, the automatic operation of the device is achieved through the regulation of the automatic control system.

2. The method for granulating sludge using a sludge granulation device with iron-carbon coupled mesh packing for interception, drying, and refeeding, as described in claim 1, is characterized in that... The variable frequency motor (5) is a motor that can realize speed regulation, forward rotation and reverse rotation.

3. The method for granulating sludge using a sludge granulation device with iron-carbon coupled mesh packing for interception, drying, and refeeding, as described in claim 1, is characterized in that... The automatic control system can control the valve opening and closing of the feed inlet (2), the discharge outlet (4) and the overflow outlet (3) at regular intervals, as well as the speed, direction and running time of the variable frequency motor (5).

4. A method for granulating sludge using a sludge granulation device with iron-carbon coupled mesh packing for interception, drying, and refeeding, as described in claim 1, characterized in that... The composite packing system is centered on the stirring rod (6). Based on the diameter and height of the cylinder (1), the composite packing is connected by cable ties to form a cylindrical packing module. A distance of 5-10 cm is reserved between the packing module and the cylinder.

5. The method for granulating sludge using a sludge granulation device with iron-carbon coupled mesh packing for interception, drying, and refeeding according to claim 1, characterized in that, The iron-carbon filler (10) is iron shavings filler, and the mesh filler (11) is polyurethane biological filler.

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