A high-speed microsand sedimentation process device with sludge thickening function

Abstract

This invention relates to the field of water treatment technology and provides a high-speed micro-sand sedimentation process device with sludge thickening function. It includes a coagulation tank, a sand injection tank, a flocculation tank, and a sedimentation tank. It also includes a reflux system: an internal reflux system comprising an internal reflux pipe with its opening at the bottom of the sedimentation tank, and a micro-sand reflux pump and a hydrocyclone connected to the internal reflux pipe; and an external reflux system comprising an external reflux pipe with a distribution trough and a micro-sand reflux pump connected to it, the micro-sand reflux pump being located on one side of the sedimentation tank. This invention fully utilizes the ballast effect of the micro-sand, causing the formed suspended solid flocs to settle rapidly. Through the external reflux system, some of the discharged sludge is reintroduced into the internal reflux system to achieve sludge thickening, greatly reducing the amount of sludge discharged from the entire system and significantly increasing the sludge concentration. This results in high sludge concentration, good effluent quality, small footprint, and low power consumption.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, and in particular relates to a high-speed sedimentation process device for micro-sand with sludge thickening function. Background Technology

[0002] Sedimentation tanks, as effective facilities for removing suspended solids from water, are an indispensable process unit in water treatment processes. Their main function is to remove suspended pollutants from water, ensuring the normal operation of subsequent treatment processes. They are commonly used in wastewater pretreatment and advanced treatment. For example, sedimentation is essential for sludge-water separation after biological treatment, solid-liquid separation for heavy metal removal, and coagulation-flocculation solid-liquid separation in conventional treatment processes. Therefore, sedimentation is a crucial structure in water treatment processes.

[0003] Sedimentation tanks account for approximately 25% of the total construction cost of municipal water plants. In industrial wastewater treatment, sedimentation tanks play an even larger role. High-concentration industrial wastewaters such as papermaking wastewater, coking wastewater, and dyeing wastewater all require coagulation processes as pretreatment to ensure the normal operation of subsequent treatments.

[0004] From the perspective of sedimentation technology development, "static sedimentation" technology began to be applied in the 2010s and 2011, and is considered by researchers to be the first generation of sedimentation technology. Its main representatives are horizontal flow sedimentation tanks, radial flow sedimentation tanks, and vertical flow sedimentation tanks. After years of development, the first generation of sedimentation tanks gradually transitioned to the second generation of inclined plate and inclined tube sedimentation tanks. This type of sedimentation tank is a practical application of the shallow layer principle, improving sedimentation efficiency. With the deepening of research on sedimentation technology, loaded flocculation theory emerged as the third generation of sedimentation tank technology in the 1980s and 1990s. Currently, developed countries have developed third-generation sedimentation tanks, namely particle-loaded flocculation sedimentation tanks and sludge recirculation loaded flocculation sedimentation tanks, and these are beginning to be applied globally.

[0005] Currently, sedimentation tanks in urban water supply and wastewater treatment plants in my country mainly adopt first-generation sedimentation technology, with horizontal flow sedimentation tanks and radial flow sedimentation tanks being widely used. However, this type of tank has extremely low treatment efficiency, typically with a surface loading of 0.8–1 m³. 3 / m 2 .h (likely referring to a specific type of sedimentation tank), occupying a huge area (40-60% of the total land area of ​​a wastewater treatment plant), is no longer suitable for future development given the scarcity of urban land and increasing environmental pressure in China. In the field of industrial water treatment, we are currently in a transitional period from first-generation to second-generation sedimentation technologies. Inclined plate sedimentation tanks are increasingly being used in various water treatment process combinations, but their treatment efficiency improvement is limited, typically with a surface loading of 2-4 m³. 3 / m 2 Furthermore, industrial wastewater is complex, and its treatment effect is not ideal.

[0006] High-speed microsand sedimentation technology belongs to the third generation of sedimentation technology. It involves adding insoluble microsand particles to the sedimentation tank to reduce the difficulty of colloid instability, improve floc settling performance, enhance the flocculation process, and accelerate solid-liquid separation. From the definitions of traditional flocculation and loaded flocculation, the role of microsand loading mainly focuses on two aspects: firstly, strengthening the flocculation process; and secondly, increasing the density of the flocs. Addressing the problems of weak buffering capacity and large water quality fluctuations in traditional flocculation applications, loaded flocculation not only effectively solves these problems but also significantly reduces the residual rate of heavy metals, thus reducing the total emission of heavy metals; effectively increases the flocculation rate and saves flocculation time; effectively increases floc strength and particle size, improving floc settling performance; and requires relatively less coagulant. Particularly noteworthy is that the sedimentation tank occupies only 5-10% of the area of ​​a conventional sedimentation tank, and the effluent quality is stable. Given the increasing scarcity of urban land, this technology has a promising future in the water treatment field. While microsand sedimentation tanks possess unparalleled advantages, they also have their own technological drawbacks. Micro-sand sedimentation tanks require external sand circulation and separation, and the sludge concentration discharged is low. They do not have the sludge thickening function of high-density sedimentation tanks, so sludge thickening tanks are needed to further thicken the sludge. This results in a loss of system water volume and an increase in the overall project cost. Summary of the Invention

[0007] The purpose of this invention is to provide a high-speed micro-sand sedimentation process device with sludge thickening function, which aims to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A high-speed micro-sand sedimentation process device with sludge thickening function includes a coagulation tank, a sand injection tank, a flocculation tank, and a sedimentation tank, and further includes:

[0010] The reflux system includes an internal reflux system and an external reflux system. The internal reflux system includes an internal reflux pipe, the open end of which is located at the bottom of the sedimentation tank. A micro-sand reflux pump and a hydrocyclone are connected to the internal reflux pipe. The external reflux system includes an external reflux pipe, on which a distribution trough and a micro-sand reflux pump are connected. The micro-sand reflux pump is located on one side of the sedimentation tank.

[0011] The coagulation tank, sand injection tank, and flocculation tank are respectively equipped with a first vertical mixer, a second vertical mixer, and a third vertical mixer. The coagulation tank, sand injection tank, flocculation tank, and sedimentation tank are separated into independent reaction zones by partition walls.

[0012] Furthermore, the external reflux system adjusts the sludge return flow rate by installing a weir plate in the distribution tank or a valve on the external reflux pipe.

[0013] Furthermore, the micro-sand return pump is connected to a hydrocyclone via an inner return pipe. The hydrocyclone is used to separate mud and sand and discharge mud to a distribution tank. The distribution tank is connected to the micro-sand return pump via an outer return pipe.

[0014] Furthermore, a sludge scraper is installed inside the sedimentation tank, and an inclined component is provided on the upper side of the interior of the sedimentation tank, with a water collection trough above the inclined component.

[0015] Furthermore, the coagulation tank, sand injection tank, flocculation tank and sedimentation tank are all rectangular, the sedimentation tank has a sludge hopper in the center, and the bottom surface of the sedimentation tank has an inclined surface with a slope of 5-15% towards the sludge hopper.

[0016] Furthermore, the blade diameters of the first, second, and third vertical mixers are all 1 / 2 to 1 / 3 of the width of the pool in which they are located.

[0017] Furthermore, the micro-sand high-speed sedimentation process device with sludge thickening function uses micro-sand with a particle size of 100-200 micrometers.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] This high-speed sedimentation process device with sludge thickening function integrates a coagulation tank, sand injection tank, flocculation tank, and sedimentation tank into a single unit. It fully utilizes the ballast effect of micro-sand to rapidly settle the formed suspended solid flocs. Through an external reflux system, a portion of the discharged sludge is reintroduced into the internal reflux system, achieving sludge thickening and significantly reducing the amount of sludge discharged from the entire system. This greatly increases the sludge concentration, resulting in high sludge concentration, excellent effluent quality, small footprint, and low power consumption. Furthermore, the micro-sand recovery rate of this device exceeds 99.3%, and the discharged sludge concentration is higher than 0.65-1.6%. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a high-speed sedimentation process device with sludge thickening function.

[0021] In the diagram: 1-Inlet pipe, 2-Coagulation tank, 3-Sand injection tank, 4-Flocculation tank, 5-Sedimentation tank, 6-Outlet pipe, 7-Micro-sand return pump, 8-Cyclone, 9-First vertical mixer, 10-Second vertical mixer, 11-Third vertical mixer, 12-Inclined component, 13-Collection tank, 14-Sludge scraper, 15-Distribution tank, 16-External return pipe, 17-Internal return pipe. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0024] like Figure 1 As shown, an embodiment of the present invention provides a high-speed micro-sand sedimentation process device with sludge thickening function, including a coagulation tank 2, a sand injection tank 3, a flocculation tank 4, and a sedimentation tank 5, and further including:

[0025] The reflux system includes an internal reflux system and an external reflux system. The internal reflux system includes an internal reflux pipe 17, the open end of which is located at the bottom of the sedimentation tank 5. A micro-sand reflux pump 7 and a hydrocyclone 8 are respectively connected to the internal reflux pipe 17. The external reflux system includes an external reflux pipe 16, on which a distribution trough 15 and a micro-sand reflux pump 7 are respectively connected. The micro-sand reflux pump 7 is located on one side of the sedimentation tank 5.

[0026] The coagulation tank 2, sand injection tank 3 and flocculation tank 4 are respectively equipped with a first vertical mixer 9, a second vertical mixer 10 and a third vertical mixer 11. The coagulation tank 2, sand injection tank 3, flocculation tank 4 and sedimentation tank 5 are separated into independent reaction zones by partition walls.

[0027] In this embodiment of the invention, preferably, the coagulation tank 2 has an inlet pipe 1 at the bottom and the sedimentation tank 5 has an outlet pipe 6 at the top; the sand injection tank 3, the flocculation tank 4 and the sedimentation tank 5 contain micro-sand circulating in them, and the micro-sand return pump 7 on one side of the sedimentation tank 5 pumps the sludge and mud. The sludge and mud are sent to the hydrocyclone 8 through the return sludge pump 7 and the inner return pipe 17, and then the sludge and mud are separated. The micro-sand is returned to the sand injection tank 3, and the sludge is discharged from the upper part of the hydrocyclone 8 into the distribution tank 15. Part of the sludge is discharged outside the system, and the other part of the sludge is returned to the suction pipe of the micro-sand return pump 7 through the outer return pipe 16 for concentration and circulation.

[0028] like Figure 1 As shown, in a preferred embodiment of the present invention, the external reflux system adjusts the sludge return flow rate by setting a weir plate in the distribution tank 15 or setting a valve on the external reflux pipe 16.

[0029] In this embodiment of the invention, preferably, the sludge concentration discharged from the distribution tank 15 is 0.65%-1.6%.

[0030] like Figure 1As shown, in a preferred embodiment of the present invention, the micro-sand return pump 7 is connected to the hydrocyclone 8 through the inner return pipe 17. The hydrocyclone 8 is used to separate mud and sand and discharge mud to the distribution tank 15. The distribution tank 15 is connected to the micro-sand return pump 7 through the outer return pipe 16.

[0031] In this embodiment of the invention, preferably, the total circulation flow rate of the micro-sand return pump 7 is 3-11% of the total inlet water flow rate.

[0032] like Figure 1 As shown, in a preferred embodiment of the present invention, a sludge scraper 14 is installed inside the sedimentation tank 5, an inclined member 12 is provided on the upper side of the interior of the sedimentation tank 5, and a water collection trough 13 is provided above the inclined member 12.

[0033] In a preferred embodiment of the invention, the inclined member 12 is an inclined tube or an inclined plate, and the water collection tank 13 is used to collect clarified water and converge it into the main water collection channel.

[0034] like Figure 1 As shown, in a preferred embodiment of the present invention, the coagulation tank 2, sand injection tank 3, flocculation tank 4 and sedimentation tank 5 are all rectangular. The sedimentation tank 5 has a sludge hopper at its center, and the bottom surface of the sedimentation tank 5 has a slope of 5-15% towards the sludge hopper.

[0035] In this embodiment of the invention, preferably, the upward flow velocity of the sedimentation tank 5 is 30-95 m / h.

[0036] like Figure 1 As shown, in a preferred embodiment of the present invention, the blade diameters of the first vertical mixer 9, the second vertical mixer 10, and the third vertical mixer 11 are all 1 / 2 to 1 / 3 of the width of the pool.

[0037] like Figure 1 As shown in the preferred embodiment of the present invention, the microsand high-speed sedimentation process device with sludge thickening function uses microsand with a particle size of 100-200 micrometers.

[0038] Example 1

[0039] For a water treatment plant with a capacity of 100,000 tons / day, assuming an influent SS of 100 mg / L and an effluent SS of ≤10 mg / L, using a conventional micro-sand sedimentation tank, the sludge discharge flow rate is calculated to be 133 m³ / h. 3 / h, sludge concentration is 2650-2919mg / L.

[0040] By using a micro-sand sedimentation tank with sludge thickening function, the sludge discharge flow rate is only 26 m³ / h while achieving the same effluent quality. 3The flow rate is reduced by 80.5% per hour, and the sludge concentration discharged is 15000 mg / L (1.5%), which is 5.3 times higher than the sludge concentration. The sludge can be directly fed into the filter press for dewatering without thickening, saving the investment in sludge thickening tanks and resulting in considerable economic benefits.

[0041] Typically, micro-sand sedimentation tanks without sludge thickening functions discharge sludge with extremely low concentrations, requiring sludge thickening tanks to concentrate it to a concentration of over 1% before dewatering. Two actual case studies from 2017, using micro-sand sedimentation tanks without thickening functions provided by our company, illustrate this. This project treated 20,000 cubic meters of domestic sewage discharged directly into a river, with a treatment capacity of 20,000 cubic meters per day and a sludge discharge flow rate of 32 cubic meters per hour; the sludge thickening tank had a volume of 50 m³. 3 The surface area is 20m² 2 The cost is 290,000 yuan, and the cost of the sludge thickening tank accounts for 10% of the total project investment. Therefore, the micro-sand sedimentation tank process device with sludge thickening function has a high cost performance.

[0042] Example 2

[0043] The system employs an internal and external sludge return system for micro-sand recovery and sludge thickening, eliminating the risk of clogging; the micro-sand recovery rate is ≥99.3%, and the concentration of discharged sludge is higher than 0.65-1.6%.

[0044] Using a high-speed microsand sedimentation process device with sludge thickening function, the hydraulic retention time (HRT) of water in coagulation tank 2 is 2-5 min, the hydraulic retention time (HRT) of water in sand injection tank 3 is 2-5 min, and the hydraulic retention time (HRT) of water in flocculation tank 4 is 8-15 min.

[0045] The working principle of this invention is:

[0046] The micro-sand high-speed sedimentation process device with sludge thickening function pumps sludge and sand through a micro-sand return pump 7 on one side of the sedimentation tank 5. The sludge and sand are sent to the hydrocyclone 8 through the return sludge pump 7 and the inner return pipe 17 for sludge and sand separation. The micro-sand is returned to the sand injection tank 3, and the sludge is discharged from the upper part of the hydrocyclone 8 into the distribution tank 15. Part of the sludge is discharged outside the system, and the other part of the sludge is returned to the suction pipe of the micro-sand return pump 7 through the outer return pipe 16 for thickening and circulation.

[0047] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A microsand high-speed sedimentation process device with sludge concentration function, comprising a coagulation tank, a sand injection tank, a flocculation tank and a sedimentation tank, characterized in that, Also includes: The reflux system includes an internal reflux system and an external reflux system. The internal reflux system includes an internal reflux pipe (17), the open end of which is located at the bottom of the sedimentation tank (5). A micro-sand reflux pump (7) and a hydrocyclone (8) are connected to the internal reflux pipe (17). The external reflux system includes an external reflux pipe (16), a distribution trough (15) and a micro-sand reflux pump (7) are connected to the external reflux pipe (16). The micro-sand reflux pump (7) is located on one side of the sedimentation tank (5). The coagulation tank (2), sand injection tank (3) and flocculation tank (4) are respectively equipped with a first vertical mixer (9), a second vertical mixer (10) and a third vertical mixer (11). The coagulation tank (2), sand injection tank (3), flocculation tank (4) and sedimentation tank (5) are separated into independent reaction zones by partition walls. The micro-sand return pump (7) is connected to the hydrocyclone (8) through the inner return pipe (17). The hydrocyclone (8) is used to separate mud and sand and discharge mud to the distribution tank (15). The distribution tank (15) is connected to the micro-sand return pump (7) through the outer return pipe (16). The micro-sand return pump (7) on one side of the sedimentation tank (5) pumps mud and sand. The mud and sand are sent to the hydrocyclone (8) through the micro-sand return pump (7) and the inner return pipe (17). The mud and sand are then separated in the hydrocyclone (8). The separated micro-sand is returned to the sand injection tank (3). The separated sludge is discharged from the upper part of the hydrocyclone (8) and enters the distribution tank (15). A part of the separated sludge is discharged outside the system, and another part of the separated sludge is returned to the suction pipe of the micro-sand return pump (7) through the outer return pipe (16) for concentration and circulation. The external reflux system adjusts the sludge reflux flow rate by setting a weir plate in the distribution tank or a valve on the external reflux pipe. The micro-sand recovery rate of the device is ≥99.3%, and the sludge concentration discharged from the distribution tank (15) is 0.65%-1.6%, so that the sludge does not need to be concentrated and directly enters the filter press for dewatering; Using the device, the hydraulic residence time (HRT) of water in the coagulation tank (2) is 2-5 min, the hydraulic residence time (HRT) of water in the sand injection tank (3) is 2-5 min, and the hydraulic residence time (HRT) of water in the flocculation tank (4) is 8-15 min.

2. The microsand high speed settling process device with sludge concentration function according to claim 1, characterized in that, The sludge concentration discharged from the distribution tank (15) is 1.5%-1.6%.

3. The high-speed micro-sand sedimentation process device with sludge thickening function according to claim 1, characterized in that, The sedimentation tank is equipped with a sludge scraper, and an inclined component is provided on the upper side of the interior of the sedimentation tank. A water collection trough is provided above the inclined component.

4. The high-speed micro-sand sedimentation process device with sludge thickening function according to claim 3, characterized in that, The coagulation tank, sand injection tank, flocculation tank and sedimentation tank are all rectangular. The sedimentation tank has a sludge hopper in the center and the bottom surface of the sedimentation tank has an inclined surface with a slope of 5-15% towards the sludge hopper.

5. The high-speed micro-sand sedimentation process device with sludge thickening function according to claim 1, characterized in that, The blade diameters of the first, second, and third vertical mixers are all 1 / 2 to 1 / 3 of the width of the pool.

6. The high-speed microsand sedimentation process device with sludge thickening function according to any one of claims 1-5, characterized in that, The micro-sand high-speed sedimentation process device with sludge thickening function uses micro-sand particles with a diameter of 100-200 micrometers.

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