Concrete mixing plant sewage sedimentation tank and sewage treatment method

Abstract

This invention discloses a sedimentation tank for wastewater from a concrete mixing plant, comprising a primary sedimentation tank, a secondary sedimentation tank, a tertiary sedimentation tank, and a quaternary sedimentation tank arranged in stages. The primary sedimentation tank is connected to the secondary sedimentation tank via an overflow outlet, and the tertiary sedimentation tank is connected to the quaternary sedimentation tank via an overflow outlet. The bottom wall of the primary sedimentation tank is a ramp, and the overflow outlet between the primary and secondary sedimentation tanks is located at the top of the ramp. A first stirring device is installed on the secondary sedimentation tank, and a filter press is installed on one side of the secondary sedimentation tank. The filter press is connected to the secondary sedimentation tank via a suction pipe and a return pipe. A flocculant addition structure is installed on the secondary sedimentation tank. A second stirring device is installed on the tertiary sedimentation tank. The secondary, tertiary, and quaternary sedimentation tanks are all polygonal structures. This invention reduces the cleaning frequency of the sedimentation tank, improves water quality indicators, ensures compliant treatment, and allows the wastewater to be discharged or used for site cleaning or road dust suppression.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment. More specifically, this invention relates to sedimentation tanks for wastewater from concrete mixing plants and wastewater treatment methods. Background Technology

[0002] The current wastewater treatment system for concrete mixing plants still uses the existing sedimentation tanks, which are set up in three stages. Wastewater settles in a progressive manner, from sludge to turbidity to clear material. This process is relatively slow, and the sedimentation tanks are easily filled with sediment, resulting in low sedimentation efficiency. To improve the efficiency of the sedimentation tanks, maximize their functionality, and effectively address the proper discharge of settled wastewater, it is necessary to develop a new type of wastewater sedimentation tank for concrete mixing plants. Summary of the Invention

[0003] The purpose of this invention is to provide a sedimentation tank and wastewater treatment method for concrete mixing plants. A primary sloping sedimentation tank is installed to facilitate timely removal of sediment. The clarified wastewater from the primary sedimentation tank overflows into a secondary sedimentation tank for further agitation, preventing the sedimentation of silt and sand. To facilitate timely treatment of sediment in the secondary sedimentation tank, a filter press is installed on one side. Turbid wastewater in the secondary sedimentation tank is thoroughly agitated and pumped into the filter press, which presses and shapes plastic impurities. After the impurities are removed, the wastewater flows back into the secondary sedimentation tank. To promote rapid sedimentation, a flocculant is added to the secondary tank, and the clarified water flows into the tertiary and quaternary sedimentation tanks respectively. The advantages of this structure are: no impurities at the bottom of the tank, reduced frequency of sedimentation tank cleaning, improved water quality indicators, compliant treatment, and wastewater that is ready for discharge can be used for site cleaning or road dust suppression.

[0004] To achieve these objectives and other advantages of the present invention, a wastewater sedimentation tank for a concrete mixing plant is provided, comprising a primary sedimentation tank, a secondary sedimentation tank, a tertiary sedimentation tank, and a quaternary sedimentation tank arranged in stages. The primary sedimentation tank is connected to the secondary sedimentation tank via an overflow outlet, and the tertiary sedimentation tank is connected to the quaternary sedimentation tank via an overflow outlet. The bottom wall of the primary sedimentation tank is a ramp, and the overflow outlet between the primary and secondary sedimentation tanks is located at the top of the ramp. A first stirring device is installed on the secondary sedimentation tank, and a filter press is installed on one side of the secondary sedimentation tank. The filter press is connected to the secondary sedimentation tank via a suction pipe and a return pipe. A flocculant addition structure is installed on the secondary sedimentation tank. A second stirring device is installed on the tertiary sedimentation tank. The secondary, tertiary, and quaternary sedimentation tanks are all polygonal structures.

[0005] Preferably, in the wastewater sedimentation tank of the concrete mixing plant, the secondary sedimentation tank and the tertiary sedimentation tank are both octagonal prisms, and the quaternary sedimentation tank is a cuboid structure.

[0006] Preferably, in the wastewater sedimentation tank of the concrete mixing plant, the secondary sedimentation tank is connected to the tertiary sedimentation tank through an overflow outlet.

[0007] Preferably, in the wastewater sedimentation tank of the concrete mixing plant, each overflow outlet is S-shaped.

[0008] Preferably, in the wastewater sedimentation tank of the concrete mixing plant, the secondary sedimentation tank is provided with an annular first baffle and an annular second baffle. Both the first and second baffles are vertically arranged, with their bottoms fixedly connected to the lower part of the secondary sedimentation tank and their inclined sidewalls. Their tops are separated from the secondary sedimentation tank by a certain distance. The second baffle is located outside the first baffle, and a rotating downward channel is provided between the second baffle and the first baffle. The top of the first baffle is higher than the top of the second baffle. The lower part of the first baffle has a first inlet and a second inlet. A second mixing zone is formed between the sidewall of the second baffle and the sidewall of the secondary sedimentation tank. The first mixing device includes a drive device, a mixing shaft, multiple first mixing blades, and at least one second mixing blade. The blades, drive device, and stirring shaft are connected. Except for its top, the stirring shaft is located inside the first partition. The interior of the first partition forms a first stirring zone. Each first stirring blade is fixed on the stirring shaft. One end of each second stirring blade is fixed on the stirring shaft, and the other end passes through the area between the top of the first and second partitions and the secondary sedimentation tank, extending downward into the second stirring zone. The overflow outlet of the primary sedimentation tank and the secondary sedimentation tank is connected to the first inlet. The bottom of the channel is connected to the second inlet. The suction pipe is connected to the first stirring zone and does not interfere with the rotation of the stirring shaft and the first stirring blades. The return water pipe is selectively connected to the second stirring zone or the tertiary sedimentation tank and does not affect the rotation of the second stirring blades. The flocculant outlet of the flocculant addition structure is connected to or opposite the second stirring zone.

[0009] Preferably, in the wastewater sedimentation tank of the concrete mixing plant, the second stirring blade has multiple blades, the driving device drives a driving gear to rotate, the top of the stirring shaft is provided with a driven gear that meshes with the driving gear, the top of the stirring shaft and the upper part of the second stirring blade are both hollow inside and connected to each other, the top of the stirring shaft forms a flocculant inlet, the upper part of the second stirring blade is provided with a flocculant outlet, and the flocculant outlet is opposite to the second stirring zone.

[0010] Preferably, a water quality concentration monitor is installed in the second mixing zone of the wastewater sedimentation tank of the concrete mixing plant.

[0011] The wastewater sedimentation tank of the concrete mixing plant also includes:

[0012] A water pump is connected to the second mixing zone and the filter press via a pumping pipe and a delivery pipe, respectively.

[0013] The controller is connected to both the water quality concentration monitor and the water pump.

[0014] Preferably, in the wastewater sedimentation tank of the concrete mixing plant, the height of the portion of the top of the second baffle that is opposite to the top of the channel is lower than the height of the other portions of the second baffle.

[0015] Preferably, in the wastewater sedimentation tank of the concrete mixing plant, both the first inlet and the second inlet are located at the bottom of the first partition.

[0016] The wastewater treatment method using the sedimentation tank of a concrete mixing plant includes the following steps:

[0017] Wastewater settled in the primary sedimentation tank flows through the overflow outlet between the primary and secondary sedimentation tanks into the first mixing zone. After being stirred by the first stirring blades, it is pumped into the filter press for pressure filtration through the suction pipe. Then, the wastewater flows into the second mixing zone through the return pipe. The water quality concentration monitor monitors the water quality concentration in the second mixing zone in real time. When the preset concentration is reached, the controller controls the water pump to start and pumps the wastewater in the second mixing zone into the filter press for pressure filtration through the suction pipe. After that, the wastewater flows back into the second mixing zone through the return pipe.

[0018] Flocculant is added to the second mixing zone through the flocculant inlet at the top of the mixing shaft. After being stirred by the second mixing blade, the flocculant mixes with the sewage and then overflows into the channel between the second baffle and the first baffle, flowing from top to bottom. During this process, particles with flocculation properties in the water collide with each other and aggregate to form larger flocs. Then, the flocs enter the first mixing zone through the second inlet. After being stirred by the first mixing blade, they are pumped into the filter press through the suction pipe for pressure filtration. After that, the sewage enters the tertiary sedimentation tank through the return pipe.

[0019] After being stirred by the second stirring device, the wastewater flows through the overflow outlet between the tertiary and quaternary sedimentation tanks to the quaternary sedimentation tank for treatment.

[0020] The present invention has at least the following beneficial effects:

[0021] This invention incorporates a primary sloping sedimentation tank for convenient and timely sludge removal. Wastewater clarified in the primary sedimentation tank overflows into a secondary sedimentation tank for further agitation, preventing the sedimentation of fine sand and other contaminants. To facilitate timely treatment of sediment in the secondary sedimentation tank, a filter press is installed on one side. Turbid wastewater in the secondary sedimentation tank is thoroughly agitated and pumped into the filter press, where plastic impurities are pressed and shaped. After this impurity-free treatment, the wastewater flows back into the secondary sedimentation tank. To promote rapid sedimentation, a flocculant is added to the secondary sedimentation tank, and the clarified water flows into the tertiary and quaternary sedimentation tanks. The advantages of this design are: no debris at the bottom of the tanks, reduced frequency of sedimentation tank cleaning, improved water quality indicators, compliant treatment, and wastewater ready for discharge can be used for site cleaning or road dust suppression.

[0022] This invention's secondary sedimentation tank is equipped with a filter press, a first stirring device, a water quality concentration monitor, and a self-priming sewage pump. Wastewater treated in the primary sedimentation tank first enters the first stirring zone for agitation to prevent the sedimentation of fine sand. After thorough agitation, it is pumped into the filter press, where plastic impurities are pressed and shaped. After this impurity-free process, the wastewater flows into the second stirring zone. To facilitate rapid sedimentation, flocculants are added to the second stirring zone. The flocculants are mixed with the wastewater by the second stirring blades and then overflow into the channel between the second and first partitions, flowing downwards. During this process, flocculating particles in the water collide and aggregate, forming larger flocs. These flocs then enter the first stirring zone through the second inlet, are agitated by the first stirring blades, and are pumped into the filter press through the suction pipe for filtration. The wastewater then enters the tertiary sedimentation tank through the return pipe. The secondary sedimentation tank, through agitation, repeated filtration, and flocculation, improves the treatment efficiency of the secondary sedimentation tank.

[0023] This invention introduces flocculant by adding it from the top of the stirring shaft. The flocculant enters the second stirring zone through the flocculant outlet on the second stirring blade. Because the second stirring blade can rotate with the stirring shaft, the flocculant can be evenly introduced into the second stirring zone during the rotation process. After entering the second stirring zone, the flocculant is stirred by the lower part of the second stirring blade, which can make the flocculant and the wastewater in the second stirring zone evenly mixed, which is beneficial to improving the flocculation efficiency.

[0024] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of a sedimentation tank according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of a secondary sedimentation tank according to an embodiment of the present invention. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0028] It should be noted that in the description of this invention, the terms "lateral", "longitudinal", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] like Figure 1 As shown, this invention provides a sedimentation tank for wastewater from a concrete mixing plant, comprising a primary sedimentation tank 1, a secondary sedimentation tank 2, a tertiary sedimentation tank 3, and a quaternary sedimentation tank 4 arranged in stages. The primary sedimentation tank 1 is connected to the secondary sedimentation tank 2 via an overflow outlet, and the tertiary sedimentation tank 3 is connected to the quaternary sedimentation tank 4 via an overflow outlet. The bottom wall of the primary sedimentation tank 1 is a ramp, and the overflow outlet between the primary sedimentation tank 1 and the secondary sedimentation tank 2 is located at the top of the ramp. A first stirring device 5 is installed on the secondary sedimentation tank 2, and a filter press is installed on one side of the secondary sedimentation tank 2. The filter press is connected to the secondary sedimentation tank 2 via a suction pipe and a return pipe. A flocculant addition structure is installed on the secondary sedimentation tank 2. A second stirring device is installed on the tertiary sedimentation tank 3. The secondary sedimentation tank 2, the tertiary sedimentation tank 3, and the quaternary sedimentation tank 4 are all polygonal structures.

[0030] This invention incorporates a primary sloping sedimentation tank for convenient and timely sludge removal. Wastewater clarified in the primary sedimentation tank 1 overflows into the secondary sedimentation tank 2 for further agitation, preventing the sedimentation of fine sand and other contaminants. To facilitate timely treatment of sediment in the secondary sedimentation tank 2, a filter press is installed on one side. Turbid wastewater in the secondary sedimentation tank 2 is thoroughly agitated and pumped into the filter press, where plastic impurities are pressed and shaped. After this impurity-free treatment, the wastewater flows back into the secondary sedimentation tank 2. To promote rapid sedimentation, a flocculant is added to the secondary sedimentation tank 2, and the clarified water flows into the tertiary and quaternary sedimentation tanks. The advantages of this design are: no debris at the bottom of the tanks, reduced frequency of sedimentation tank cleaning, improved water quality indicators, compliant treatment, and wastewater ready for discharge can be used for site cleaning or road dust suppression.

[0031] The main sources of wastewater from the mixing plant are mechanical cleaning and sand and gravel separation. Sand and gravel separation is achieved by reversing vehicles onto a reversing platform, aligning the tanker truck's unloading chute with the separator, turning on the separator, and simultaneously opening the tanker truck's unloading switch to separate the sand and gravel. The wastewater slurry flows into the primary sedimentation tank 1. The debris remaining after sedimentation in the primary sedimentation tank 1 is cleaned up by a loader. The wastewater in the tank flows into the secondary sedimentation tank 2 through the overflow outlet. After sedimentation, the wastewater flows into the tertiary and quaternary sedimentation tanks. The clarified and qualified water is used for site cleaning or dust suppression. The sediment is excavated and removed in stages.

[0032] Beneficial effects:

[0033] 1. Sedimentation tank system, equipped with a sand and gravel separator. Beneficial effect: Separates and utilizes residual concrete from the concrete tanker, enabling resource recycling and reuse.

[0034] 2. A mud and debris mixer is installed along the rim of the secondary sedimentation tank 2. Beneficial effect: Wastewater debris and mud are filtered and molded by a filter press, removing impurities from the water.

[0035] 3. The primary sedimentation tank 1 is designed with a sloping ramp, facilitating the removal of sediment and debris using a loader. Benefits: Reduces labor intensity, saves manual cleaning time, and improves work efficiency.

[0036] 4. The secondary sedimentation tank 2 is equipped with a stirring device to facilitate the sedimentation of high-density particles. Beneficial effects: High-density particles are shaped through stirring and pressure filtration, and the treated wastewater overflows into the next stage sedimentation tank, reducing equipment cleaning frequency and lowering costs.

[0037] 5. The secondary, tertiary, and quaternary sedimentation tanks are designed with a polygonal structure. Beneficial effects: During stirring, vortices are easily formed, which facilitates the mixing of sediments and wastewater and helps remove light suspended solids from the surface.

[0038] This technical solution has been promoted and used in railway, expressway, and highway reconstruction and expansion projects under construction.

[0039] 1. In response to the problems of small capacity of the primary sedimentation tank 1, difficult sediment removal, high cleaning frequency, and high cost associated with the previously used rectangular sedimentation tanks, this application innovatively changes the structural design of each stage of the sedimentation tank. It sets up a slope for the primary tank to facilitate cleaning and configures polygonal secondary, tertiary, and quaternary sedimentation tanks, which is conducive to the formation of vortices by overflow, making it easier to remove suspended light materials.

[0040] 2. Through on-site verification, it was found that the original rectangular sedimentation tank design did not have a stirring device installed. In comparison, the latter is more convenient for sludge cleaning, has higher work efficiency, and better sewage sedimentation effect.

[0041] In the wastewater sedimentation tanks of the concrete mixing plant, the secondary sedimentation tank 2 and the tertiary sedimentation tank 3 are both octagonal prisms, and the quaternary sedimentation tank 4 is a cuboid structure.

[0042] In the wastewater sedimentation tank of the concrete mixing plant, the secondary sedimentation tank 2 is connected to the tertiary sedimentation tank 3 through an overflow outlet.

[0043] In the wastewater sedimentation tank of the concrete mixing plant, each overflow outlet is S-shaped to prevent sediment from overflowing directly into the next stage.

[0044] In the wastewater sedimentation tank of the concrete mixing plant, such as Figure 2 As shown, the secondary sedimentation tank 2 is equipped with an annular first baffle 21 and an annular second baffle 22. Both the first baffle 21 and the second baffle 22 are vertically arranged, with their bottoms fixedly connected to the inclined side walls of the secondary sedimentation tank 2 at the bottom. Their tops are separated from the secondary sedimentation tank 2 by a certain distance. The second baffle 22 is located outside the first baffle 21. A rotating channel is provided between the second baffle 22 and the first baffle 21. The top of the first baffle 21 is higher than the top of the second baffle 22, so that wastewater in the second mixing zone can only overflow between the first baffle 21 and the second baffle 22, and cannot flow directly into the first baffle 21. The lower part of the first baffle 21 is provided with a first inlet 211 and a second inlet 212. The second mixing zone is formed between the side wall of the second baffle 22 and the side wall of the secondary sedimentation tank 2. The first mixing device 5 includes a drive device, a mixing shaft, multiple first mixing blades 51, and at least one second mixing blade. 52. The drive device is connected to the stirring shaft. Except for its top, the rest of the stirring shaft is located inside the first partition 21. The interior of the first partition 21 forms a first stirring zone. Each first stirring blade 51 is fixed on the stirring shaft. One end of each second stirring blade 52 is fixed on the stirring shaft, and the other end passes through the area between the top of the first partition 21 and the second partition 22 and the secondary sedimentation tank 2, and extends downward into the second stirring zone. In this way, the first partition 21 and the second partition 22 do not affect the rotation of the second stirring blade 52. The overflow port connecting the primary sedimentation tank 1 and the secondary sedimentation tank 2 is connected to the first inlet 211 through a downwardly inclined water pipe. The bottom of the channel is connected to the second inlet 212. The suction pipe is connected to the first stirring zone and does not interfere with the rotation of the stirring shaft and the first stirring blade 51. The return water pipe is selectively connected to the second stirring zone or the tertiary sedimentation tank 3 and does not affect the rotation of the second stirring blade 52. The flocculant outlet 54 of the flocculant addition structure is connected to or opposite the second stirring zone.

[0045] The wastewater treatment method using the sedimentation tank of a concrete mixing plant includes the following steps:

[0046] After sedimentation in the primary sedimentation tank 1, the wastewater flows through the overflow outlet between the primary sedimentation tank 1 and the secondary sedimentation tank 2 into the first mixing zone. After being stirred by the first stirring blade 51, it is pumped into the filter press through the suction pipe for pressure filtration. Afterward, the wastewater flows into the second mixing zone through the return pipe.

[0047] Flocculant is added to the second mixing zone and mixed with the sewage by the second mixing blade 52. Then it overflows into the channel between the second baffle 22 and the first baffle 21 and flows from top to bottom. During this process, the particles with flocculation properties in the water aggregate in the collision with each other to form larger flocs. Then it enters the first mixing zone through the second inlet 212. After being mixed by the first mixing blade 51, it is pumped into the filter press through the suction pipe for pressure filtration. Then the sewage enters the tertiary sedimentation tank 3 through the return pipe.

[0048] After being stirred by the second stirring device, the wastewater flows through the overflow outlet between the tertiary sedimentation tank 3 and the quaternary sedimentation tank 4 to the quaternary sedimentation tank 4 for treatment.

[0049] In the wastewater sedimentation tank of the concrete mixing plant, there are multiple second stirring blades 52. The driving device drives a drive gear to rotate. A driven gear meshing with the drive gear is provided at the top of the stirring shaft. The top of the stirring shaft and the upper part of the second stirring blades 52 are both hollow inside and connected to each other. A flocculant inlet 53 is formed at the top of the stirring shaft. A flocculant outlet 54 is provided at the upper part of the second stirring blades 52. The flocculant outlet 54 is opposite to the second mixing zone.

[0050] The wastewater treatment method using the sedimentation tank of a concrete mixing plant includes the following steps:

[0051] After sedimentation in the primary sedimentation tank 1, the wastewater flows through the overflow outlet between the primary sedimentation tank 1 and the secondary sedimentation tank 2 into the first mixing zone. After being stirred by the first stirring blade 51, it is pumped into the filter press through the suction pipe for pressure filtration. Afterward, the wastewater flows into the second mixing zone through the return pipe.

[0052] Flocculant is added to the second mixing zone through the flocculant inlet 53 at the top of the mixing shaft. After being stirred by the second mixing blade 52, the flocculant mixes with the sewage and then overflows into the channel between the second baffle 22 and the first baffle 21, flowing from top to bottom. During this process, particles with flocculation properties in the water agglomerate in the collision with each other, forming larger flocs, and then enter the first mixing zone through the second inlet 212. After being stirred by the first mixing blade 51, the sewage is pumped into the filter press through the suction pipe for pressure filtration. After that, the sewage enters the tertiary sedimentation tank 3 through the return pipe.

[0053] After being stirred by the second stirring device, the wastewater flows through the overflow outlet between the tertiary sedimentation tank 3 and the quaternary sedimentation tank 4 to the quaternary sedimentation tank 4 for treatment.

[0054] In this invention, flocculant is added from the top of the stirring shaft. The flocculant enters the second stirring zone through the flocculant outlet 54 on the second stirring blade 52. Since the second stirring blade 52 can rotate with the stirring shaft, the flocculant can be evenly introduced into the second stirring zone during the rotation process. After entering the second stirring zone, the flocculant is stirred by the lower part of the second stirring blade 52, which can make the flocculant and the sewage in the second stirring zone evenly mixed, which is beneficial to improving the flocculation efficiency.

[0055] In the wastewater sedimentation tank of the concrete mixing plant, a water quality concentration monitor is installed in the second mixing zone;

[0056] The wastewater sedimentation tank of the concrete mixing plant also includes:

[0057] The water pump is connected to the second mixing zone and the filter press through a water pumping pipe and a water delivery pipe, respectively. The water pumping pipe and the water delivery pipe do not affect the rotation of the second mixing blade.

[0058] The controller is connected to both the water quality concentration monitor and the water pump.

[0059] The water quality concentration monitor monitors the water quality concentration in the second mixing zone in real time. When the preset concentration is reached, the controller controls the water pump to start and pumps the sewage in the second mixing zone into the filter press for pressure filtration through the pumping pipe. After that, the sewage flows back into the second mixing zone through the return pipe.

[0060] In the wastewater sedimentation tank of the concrete mixing plant, the height of the portion of the top of the second baffle 22 opposite to the top of the channel is lower than the height of the other portions of the second baffle 22. This allows wastewater from the second mixing zone to flow through the portion of the top of the second baffle 22 opposite to the top of the channel to the top of the channel, and then from top to bottom.

[0061] In the wastewater sedimentation tank of the concrete mixing plant, the first inlet 211 and the second inlet 212 are both located at the bottom of the first partition 21, so that all the wastewater in the second mixing zone and the channel can be introduced into the first mixing zone.

[0062] The wastewater treatment method using the sedimentation tank of a concrete mixing plant includes the following steps:

[0063] Wastewater settled in primary sedimentation tank 1 flows through the overflow outlet between primary sedimentation tank 1 and secondary sedimentation tank 2 into the first mixing zone. After being stirred by the first stirring blade 51, it is pumped into the filter press for pressure filtration through the suction pipe. Afterward, the wastewater flows into the second mixing zone through the return pipe. The water quality concentration monitor monitors the water quality concentration in the second mixing zone in real time. When the preset concentration is reached, the controller controls the water pump to start and pumps the wastewater in the second mixing zone into the filter press for pressure filtration through the suction pipe. Afterward, the wastewater flows into the second mixing zone through the return pipe.

[0064] Flocculant is added to the second mixing zone through the flocculant inlet 53 at the top of the mixing shaft. After being stirred by the second mixing blade 52, the flocculant mixes with the sewage and then overflows into the channel between the second baffle 22 and the first baffle 21, flowing from top to bottom. During this process, particles with flocculation properties in the water agglomerate in the collision with each other, forming larger flocs, and then enter the first mixing zone through the second inlet 212. After being stirred by the first mixing blade 51, the sewage is pumped into the filter press through the suction pipe for pressure filtration. After that, the sewage enters the tertiary sedimentation tank 3 through the return pipe.

[0065] After being stirred by the second stirring device, the wastewater flows through the overflow outlet between the tertiary sedimentation tank 3 and the quaternary sedimentation tank 4 to the quaternary sedimentation tank 4 for treatment.

[0066] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A sedimentation tank for wastewater from a concrete mixing plant, comprising a primary sedimentation tank, a secondary sedimentation tank, a tertiary sedimentation tank, and a quaternary sedimentation tank arranged in stages, wherein the primary sedimentation tank is connected to the secondary sedimentation tank via an overflow outlet, and the tertiary sedimentation tank is connected to the quaternary sedimentation tank via an overflow outlet; characterized in that, The bottom wall of the primary sedimentation tank is a ramp, and the overflow outlet between the primary and secondary sedimentation tanks is located at the top of the ramp. The secondary sedimentation tank is equipped with a first stirring device, and a filter press is installed on one side of the secondary sedimentation tank. The filter press is connected to the secondary sedimentation tank through a suction pipe and a return pipe. The secondary sedimentation tank is equipped with a flocculant addition structure. The tertiary sedimentation tank is equipped with a second stirring device. The secondary, tertiary, and quaternary sedimentation tanks are all polygonal structures. Among them, the secondary and tertiary sedimentation tanks are both octagonal prisms, while the quaternary sedimentation tank is a cuboid structure. The secondary sedimentation tank is equipped with an annular first baffle and an annular second baffle, both of which are vertically arranged. The bottoms of both the first and second baffles are fixedly connected to the lower, inclined sidewall of the secondary sedimentation tank. The tops of both the first and second baffles are spaced a certain distance from the secondary sedimentation tank. The second baffle is located outside the first baffle, and a downward rotating channel is provided between the second and first baffles. The top of the first baffle is higher than the top of the second baffle. The lower part of the first baffle has a first inlet and a second inlet. A second stirring zone is formed between the sidewall of the second baffle and the sidewall of the secondary sedimentation tank. The first stirring device includes a drive device, a stirring shaft, multiple first stirring blades, and at least one second stirring blade. The mixing blades and drive device are connected to the mixing shaft. Except for its top, the other parts of the mixing shaft are located inside the first partition. The interior of the first partition forms a first mixing zone. Each first mixing blade is fixed on the mixing shaft. One end of each second mixing blade is fixed on the mixing shaft, and the other end passes through the area between the top of the first and second partitions and the secondary sedimentation tank, and extends downward into the second mixing zone. The overflow outlets of the primary and secondary sedimentation tanks are connected to the first inlet. The bottom of the channel is connected to the second inlet. The water suction pipe is connected to the first mixing zone and does not interfere with the rotation of the mixing shaft and the first mixing blades. The return water pipe is selectively connected to the second mixing zone or the tertiary sedimentation tank and does not affect the rotation of the second mixing blades. The flocculant outlet of the flocculant addition structure is connected to or opposite to the second mixing zone.

2. The wastewater sedimentation tank of a concrete mixing plant as described in claim 1, characterized in that, The secondary sedimentation tank is connected to the tertiary sedimentation tank through an overflow outlet.

3. The wastewater sedimentation tank of a concrete mixing plant as described in claim 2, characterized in that, Each overflow outlet is S-shaped.

4. The wastewater sedimentation tank of a concrete mixing plant as described in claim 1, characterized in that, The second stirring blade has multiple blades. The driving device drives a drive gear to rotate. The top of the stirring shaft is provided with a driven gear that meshes with the drive gear. The top of the stirring shaft and the upper part of the second stirring blade are both hollow inside and connected to each other. The top of the stirring shaft forms a flocculant inlet, and the upper part of the second stirring blade is provided with a flocculant outlet. The flocculant outlet is opposite to the second stirring zone.

5. The wastewater sedimentation tank of a concrete mixing plant as described in claim 4, characterized in that, A water concentration monitoring instrument is installed in the second mixing zone; The wastewater sedimentation tank of the concrete mixing plant also includes: A water pump is connected to the second mixing zone and the filter press via a pumping pipe and a delivery pipe, respectively. The controller is connected to both the water quality concentration monitor and the water pump.

6. The wastewater sedimentation tank of a concrete mixing plant as described in claim 5, characterized in that, The height of the top portion of the second partition, which is opposite to the top of the channel, is lower than the height of the other portions of the second partition.

7. The wastewater sedimentation tank of a concrete mixing plant as described in claim 1, characterized in that, Both the first inlet and the second inlet are located at the bottom of the first partition.

8. The wastewater treatment method using the sedimentation tank of a concrete mixing plant as described in claim 6, characterized in that, Includes the following steps: Wastewater settled in the primary sedimentation tank flows through the overflow outlet between the primary and secondary sedimentation tanks into the first mixing zone. After being stirred by the first stirring blades, it is pumped into the filter press for pressure filtration through the suction pipe. Then, the wastewater flows into the second mixing zone through the return pipe. The water quality concentration monitor monitors the water quality concentration in the second mixing zone in real time. When the preset concentration is reached, the controller controls the water pump to start and pumps the wastewater in the second mixing zone into the filter press for pressure filtration through the suction pipe. After that, the wastewater flows back into the second mixing zone through the return pipe. Flocculant is added to the second mixing zone through the flocculant inlet at the top of the mixing shaft. After being stirred by the second mixing blade, the flocculant mixes with the sewage and then overflows into the channel between the second baffle and the first baffle, flowing from top to bottom. During this process, particles with flocculation properties in the water collide with each other and aggregate to form larger flocs. Then, the flocs enter the first mixing zone through the second inlet. After being stirred by the first mixing blade, they are pumped into the filter press through the suction pipe for pressure filtration. After that, the sewage enters the tertiary sedimentation tank through the return pipe. After being stirred by the second stirring device, the wastewater flows through the overflow outlet between the tertiary and quaternary sedimentation tanks to the quaternary sedimentation tank for treatment.

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