A self-renewing high-density sedimentation tank with suspended layer and a water treatment method

Abstract

This invention discloses a high-density sedimentation tank with a self-renewing suspended layer, comprising a mixing zone, a flocculation zone, and a sedimentation zone arranged sequentially. The mixing zone includes a mixing tank and a mixing zone agitator located within the mixing tank. The mixing zone agitator includes a lower turbine blade agitation mechanism and an upper straight blade agitation mechanism. The flocculation zone includes a flocculation tank, a central cylinder, and a flocculation zone agitator. The central cylinder is placed inside the flocculation tank, and the flocculation zone agitator is placed inside the central cylinder. The flocculation zone agitator includes a lower blade agitation mechanism and an upper blade agitation mechanism. The sedimentation zone includes a sedimentation tank. The sedimentation tank, from bottom to top, consists of a sludge settling zone, a lower inclined plate zone, a water distribution zone, a suspended interception zone, an upper inclined plate zone, and an effluent zone. The inclined plates in the lower and upper inclined plate zones have different inclination directions. This invention also discloses a water treatment method. This invention can improve floc removal, improve effluent quality, and reduce operation and maintenance costs.

Description

Technical Field

[0001] This invention belongs to the field of water treatment, specifically relating to a high-density sedimentation tank with a self-renewing suspended layer and a water treatment method. Background Technology

[0002] High-density sedimentation tanks, also known as sludge recycling sedimentation tanks, integrate coagulation, flocculation, sedimentation, and sludge thickening. They feature a compact structure, reducing the footprint of water treatment systems, and can be flexibly applied to primary and advanced treatment of drinking water, industrial and domestic sewage, and rainwater. However, existing high-density sedimentation tanks typically require sludge recirculation, resulting in high operation and maintenance costs. Furthermore, the floc removal efficiency of existing high-density sedimentation tanks is not ideal, and the effluent quality needs further improvement. Summary of the Invention

[0003] The main objective of this invention is to provide a high-density sedimentation tank with a self-renewing suspended layer and a water treatment method. This high-density sedimentation tank and water treatment method can improve floc removal, improve effluent quality, and reduce operation and maintenance costs.

[0004] The technical solution adopted in this invention is:

[0005] A high-density sedimentation tank with a self-renewing suspended layer includes a mixing zone, a flocculation zone, and a sedimentation zone arranged sequentially. Incoming water and coagulant are rapidly and thoroughly stirred in the mixing zone. After the pollutants and coagulant in the incoming water are fully mixed, they enter the flocculation zone to react and form flocs. The flocs are intercepted and removed in the sedimentation zone to ensure that the effluent meets the standards.

[0006] The mixing zone includes a mixing tank and a mixing zone agitator located within the mixing tank. The mixing zone agitator includes a lower turbine blade agitation mechanism and an upper straight blade agitation mechanism arranged sequentially from bottom to top.

[0007] The flocculation zone includes a flocculation tank, a central cylinder, and a flocculation zone agitator; the central cylinder is placed inside the flocculation tank, and the flocculation zone agitator is placed inside the central cylinder; the flocculation zone agitator includes a lower layer blade agitator and an upper layer blade agitator arranged sequentially from bottom to top; the influent enters the central cylinder through the first outlet pipe, and under the action of the flocculation zone agitator, the substances and agents in the influent further react to generate flocs, which flow down through the central cylinder to the outlet of the flocculation tank and out of the flocculation zone;

[0008] The sedimentation zone uses a submerged orifice for water inlet and an overflow weir for water outlet, and includes a sedimentation tank. The sedimentation tank, from bottom to top, consists of a sludge settling zone, a lower inclined plate zone, a water distribution zone, a suspended solids interception zone, an upper inclined plate zone, and an outlet zone. The inlet of the sedimentation tank is located at the top and is connected to the outlet of the flocculation tank via the inlet zone. The sludge settling zone is connected to the inlet zone via a circulating water pump. An online suspended solids concentration measuring instrument is installed in the suspended solids interception zone. The inclined plates in the lower and upper inclined plate zones have different inclination directions. During the start-up phase, the circulating water pump circulates the settled sludge from the sludge settling zone to the inlet zone, and then into the sedimentation zone to cultivate the suspended solids layer in the suspended solids interception zone. When the suspended solids concentration in the suspended solids interception zone reaches 3-10 g / L, the circulating water pump is stopped. After reaching the specified concentration, the normal treatment period begins.

[0009] Preferably, the hydraulic retention time of the self-renewing high-density sedimentation tank is 40 min to 60 min; wherein the hydraulic retention time in the mixing zone shall not exceed 2 min, the hydraulic retention time in the flocculation zone shall be 15 min to 20 min, and the hydraulic retention time in the sedimentation zone shall be 30 min to 45 min, in order to ensure the quality of the effluent.

[0010] Preferably, the mixing tank is divided into three areas by two parallel partition plates. The upper end of the partition plates is connected to the top of the mixing tank, and the lower end has a gap with the bottom of the mixing tank. The mixing zone agitator is placed between the two partition plates. The mixing zone adopts an upper-inlet and upper-outlet weir flow pattern, that is, the water inlet of the mixing tank is placed at the top of the mixing tank and between the two partition plates; the water outlet of the mixing tank has two outlets, which are placed at the top of the mixing tank and outside the two partition plates.

[0011] Water enters the mixing zone between two partition plates through the inlet of the mixing tank. Under the stirring action of the agitator in the mixing zone, the agent is fully diffused and mixed evenly. Then, it flows up through the gap between the partition plate and the bottom of the mixing tank to the outlet at the top of the mixing tank and flows out of the mixing tank.

[0012] Preferably, the distance between the two partition plates is d1;

[0013] The upper straight-blade stirring mechanism is located 2 / 3 to 3 / 5 of the mixing tank height from the bottom of the mixing tank, and includes two straight blades; the diameter of the straight blades is 0.6d1 to 0.7d1;

[0014] The lower turbine blade stirring mechanism is located 1 / 3 to 2 / 5 of the mixing tank height from the bottom. It includes a disc and multiple turbine blades embedded around the disc. The total diameter of the lower turbine blade stirring mechanism is 0.8d1, wherein the disc diameter is 0.5d1 to 0.6d1, and the blade length is 0.5d1 to 0.6d1. Preferably, the turbine blades are 45° six-bladed. This generally achieves better mixing of the incoming water and the reagent.

[0015] Preferably, the flocculation zone adopts a bottom-in, bottom-out configuration, with water entering through a pipe and exiting through submerged holes; that is, the inlet of the flocculation tank is located at the bottom of the central cylinder and is connected to the outlet of the mixing tank through a first outlet pipe; the outlet of the flocculation tank is located at the lower part of the flocculation tank and outside the central cylinder; the above structure can better generate flocs.

[0016] Preferably, the diameter d2 of the central cylinder is 0.5 to 0.7 times the side length of the flocculation tank;

[0017] The lower blade agitator is positioned 1 / 2 to 3 / 5 of the height from the bottom of the flocculation tank, while the upper blade agitator is positioned 3 / 4 to 4 / 5 of the height from the bottom of the flocculation tank. Both the lower and upper blade agitators use 45° four-bladed blades with a total diameter of 0.9d². This structure enables better floc formation.

[0018] Preferably, the height of the water outlet zone shall not be less than 0.8m;

[0019] The height of the water distribution zone shall not be less than 1.5m; the suspended interception zone shall be controlled by changes in flow velocity to form a suspended layer;

[0020] The height of the suspended interception zone shall not be less than 1.0m; the ratio of the lower water flow area to the upper water flow area of ​​the suspended interception zone shall be 1:1.2 to 1:1.5; the above structure can better settle flocs and improve the quality of effluent.

[0021] Preferably, the upper inclined plate area is formed by multiple flat plates installed at an angle; the inclination angle of the flat plates is 50-70°, preferably 60°; the spacing between adjacent flat plates is 80-100mm; and the height of the upper inclined plate area is 0.8-1.0m.

[0022] The lower inclined plate area is formed by multiple corrugated plates installed at an angle; the wavelength of the corrugated plates is 400~500mm, and the wave height is 80~100mm; the tilt angle of the corrugated plates is 50-70°, preferably 60°; the spacing between adjacent corrugated plates is 150~300mm; the height of the lower inclined plate area is 0.8~1.0m.

[0023] The flat plate and the corrugated plate have different inclination directions, that is, the installation directions of the upper inclined plate area and the lower inclined plate area must not be the same; the above structure can better settle flocs and improve the quality of effluent.

[0024] The incoming water and reagents are rapidly mixed in the mixing zone by mechanical stirring before entering the flocculation zone. The incoming water in the mixing zone passes through the central cylinder and is stirred at low speed by the agitator in the flocculation zone, causing further reactions and gradually increasing the size of the flocs. After passing through the central cylinder, the water flow disturbance is smaller on the outside of the central cylinder, and the flocs increase in size further before entering the sedimentation zone. The suspended interception zone in the sedimentation zone forms a dynamic suspended layer that can be automatically renewed through changes in flow velocity. After the incoming water in the flocculation zone passes through the sedimentation zone, the flocs are intercepted and removed.

[0025] The present invention also provides a water treatment method, which uses the above-mentioned self-renewing high-density sedimentation tank with suspended layer, and includes the following steps:

[0026] The incoming water and coagulant are rapidly and thoroughly mixed in the mixing zone; after the pollutants and agents in the incoming water are fully mixed, they enter the flocculation zone to react and generate flocs; the flocs then enter the sedimentation zone.

[0027] During the start-up phase, the suspended layer in the suspended interception zone of the sedimentation zone needs to be cultivated. Specifically, during the start-up phase, the circulating water pump circulates the settled sludge from the sedimentation zone to the outlet of the flocculation zone. When the suspended solids concentration in the suspended interception zone reaches 3-10 g / L, the circulating water pump is stopped, and the treatment phase begins. If the suspended layer concentration in the suspended interception zone does not meet the requirements during the treatment phase, the circulating water pump is turned on until the required concentration is reached, and then turned off.

[0028] After entering the sedimentation zone, the flocs flow upwards to the lower inclined plate zone. Some of the larger suspended solids settle in the lower inclined plate zone. Due to the aggregation effect of the troughs of the corrugated plates, the suspended solids settle and compress at the troughs, forming a larger and denser floc structure. After accumulating and compressing to a certain extent, they slide down to the sludge zone at the bottom of the sedimentation tank. Because of their increased particle size and density, these flocs have a stronger resistance to being carried up by the upward water flow, making them easier to settle quickly at the bottom of the sedimentation tank and less likely to be rolled up. The smaller suspended solids then move upwards through the lower inclined plate zone to reach the suspension interception zone.

[0029] Due to the presence of the suspended layer in the suspended interception zone, some suspended matter is intercepted and adsorbed, resulting in contact flocculation, which increases the particle size and density. Subsequently, it flows against the direction of water flow and slides down to the lower inclined plate zone to be removed; the other part continues to flow upward with the water flow to the upper inclined plate zone.

[0030] Some of the sludge settles in the upper inclined plate zone and slides down to the suspended interception zone, promoting the autonomous dynamic renewal of the suspended layer in the suspended interception zone. Due to the presence of the lower inclined plate zone and the suspended layer in the suspended interception zone, the sedimentation tank enhances its interception effect on suspended solids, and the contact flocculation effect is effectively utilized. This allows the sludge to eventually settle in the sedimentation zone without external sludge return, thanks to the presence of carrier flocculation and the dynamic renewal of the sludge suspended layer. The treated water flows out from the effluent zone at the top of the sedimentation tank.

[0031] The beneficial effects of this invention are as follows:

[0032] The modified mixing zone agitator consists of a lower turbine blade mixing mechanism and an upper straight blade mixing mechanism, enabling rapid and uniform mixing of chemicals. This addresses the problem in ordinary high-density sedimentation tanks where, at high mixing speeds, the water flow rotates as a whole with the agitator, hindering rapid and uniform mixing of chemicals. Experiments and simulations show that the mixing efficiency of this invention is 10%-20% higher than that of ordinary sedimentation tanks, while the mixing time is reduced by 10%-20%.

[0033] The combination of the agitator in the flocculation zone and the central cylinder creates an environment with a higher internal G-value and a lower external G-value. After entering through the inlet, the water rises against gravity to the vicinity of the agitator blades in the central cylinder's flocculation zone. Under the combined action of gravity and the agitator blades, a flocculation reaction occurs, and flocs grow. Once the flocs reach a certain particle size in the central cylinder, they flow with the water into the outside of the central cylinder. Here, the G-value is lower, which effectively prevents the flocs from breaking. This provides a favorable environment for floc growth and further increase in particle size. Therefore, the generated flocs are denser than those in ordinary high-density sedimentation tanks, providing the prerequisites for the subsequent formation and sedimentation of the suspended layer.

[0034] The purpose of setting up a lower inclined plate zone, an upper inclined plate zone, and a suspended interception zone (variable speed zone) in the sedimentation tank is to form a stable suspended layer, further improving the floc removal rate. After the flocs generated in the flocculation zone enter the sedimentation zone, they first pass through the lower inclined plate zone, where some larger flocs are intercepted and directly settle. Simultaneously, the corrugated peaks and troughs of the lower inclined plate zone promote further floc growth and aggregation, facilitating sedimentation and mitigating the disadvantage of difficult-to-clean sediment in the lower inclined plate zone. Flocs of suitable size enter the variable speed zone through the lower inclined plate zone, where their speed slows down. Because the upper inclined plate zone provides some resistance to the flocs, some flocs can remain suspended in this area under the influence of the upward water flow, forming a suspended layer. This suspended layer acts as "nuclei" for subsequent flocs, colliding to form larger flocs. When their particle size increases to a certain extent, they can resist the upward water flow and settle in the lower inclined plate zone, finally sinking to the bottom of the sedimentation zone for removal. The presence of a suspended layer effectively intercepts small flocs that are difficult to settle in the water flow, allowing them to continue growing to a certain size before removal. This eliminates the need for sludge recirculation; the stability of the suspended layer is achieved solely through improved hydraulic conditions. Simultaneously, the suspended layer is self-renewing: larger flocs with fewer effective flocculation points collide and combine, then settle and are removed; smaller flocs with more effective flocculation points are partially retained in the variable-velocity zone by the water flow, while others rise with the flow to the upper inclined plate zone, settle there, and then slide back down to the variable-velocity zone, serving as "nuclei" for subsequent flocs, thus creating a continuous cycle. Experiments and simulations show that the effluent suspended solids removal rate of this invention is 35%-45% higher than that of ordinary high-density sedimentation tanks.

[0035] The system consists of a lower inclined plate zone and an upper inclined plate zone (double-layer inclined plates) to ensure the stability of the suspended layer and improve treatment efficiency. The lower inclined plate zone uses corrugated inclined plates to prevent sludge accumulation and clogging, which could negatively impact the subsequent effluent quality.

[0036] This invention rationalizes the flow patterns at each stage of a high-density sedimentation tank, maximizing the effective volume and minimizing dead and backflow zones, thus fully utilizing the tank's treatment potential and increasing the actual effective volume. After the incoming water enters the high-density sedimentation tank, it undergoes mixing and flocculation, providing a foundation for subsequent sedimentation stages. Because the tank design ensures a thorough reaction process, it promotes floc growth; therefore, the resulting flocs are superior to those from existing high-density sedimentation tanks in both density and size.

[0037] Compared to existing high-density sedimentation tanks, this system features a double-layered inclined plate at different angles in the sedimentation zone, allowing water to fully utilize sedimentation on both layers. Variations in water flow velocity create a suspended interception zone, maximizing the advantages of contact flocculation. The double-layered inclined plate maintains a stable suspended layer, allowing flocs settled on the upper layer to slide down and replenish it. Larger flocs within the suspended layer settle on the lower layer, enabling dynamic renewal of the suspended layer without external force. This improves treatment efficiency while saving on external circulation costs. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of a high-density sedimentation tank with a self-renewing suspended layer.

[0040] Figure 2 This is a schematic diagram of the mixing zone;

[0041] Figure 3 This is a schematic diagram of the flocculation zone.

[0042] Figure 4 This is a schematic diagram of the sedimentation zone;

[0043] Figure 5 These are comparison images showing the treatment effects of a conventional high-density sedimentation tank and the present invention at different times.

[0044] In the diagram: 1-Mixing zone; 2-Flocculation zone; 3-Sedimentation zone; 4-Circulating water pump; 5-First outlet pipe; 101-Inlet of mixing zone; 102-Baffle plate; 103-Mixing zone agitator; 104-Mixing zone outlet; 10301-Upper straight blade agitator; 10302-Lower turbine blade agitator; 105-Mixing tank; 201-Inlet of flocculation zone; 202-Outlet of flocculation zone ; 203-Central cylinder; 204-Flocculation zone agitator; 20401-Upper blade agitator; 20402-Lower blade agitator; 205-Flocculation tank; 301-Inlet zone; 302-Sedimentation zone; 303-Lower inclined plate zone; 304-Water distribution zone; 305-Suspended interception zone; 306-Upper inclined plate zone; 307-Outlet zone; 308-Online suspended solids concentration measuring instrument; 309-Sedimentation tank. Detailed Implementation

[0045] 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.

[0046] Example 1

[0047] See Figures 1-4 A suspended layer self-renewing high-density sedimentation tank includes a mixing zone 1, a flocculation zone 2, and a sedimentation zone 3 arranged sequentially. The incoming water and coagulant are rapidly and thoroughly stirred in the mixing zone 1. After the pollutants and agents in the incoming water are fully mixed, they enter the flocculation zone 2 to react and form flocs. The flocs are intercepted and removed in the sedimentation zone 3 to ensure that the effluent meets the standards.

[0048] Mixing zone 1 includes a mixing tank 105 and a mixing zone agitator 103. Two partition plates 102 are arranged parallel to each other within the mixing tank 105, dividing the tank into three areas. The upper end of each partition plate 102 is connected to the top of the mixing tank 105, while the lower end has a gap with the bottom of the mixing tank 105. Mixing zone 1 adopts an upward-inflow, upward-outflow weir flow pattern to prevent the water entering mixing zone 1 from undergoing overall swirling under the action of the mixing zone agitator 103. Specifically, the inlet 101 of the mixing tank is located at the upper part of the mixing tank 105, between the two partition plates 102; the mixing tank has two outlets 104, located at the upper part of the mixing tank 105, outside the two partition plates 102. The mixing zone agitator 103 is located between the two partition plates 102 and includes a lower turbine blade agitator 10302 and an upper straight blade agitator 10301 arranged sequentially from bottom to top. The distance between the two partition plates 102 is d1. The upper straight-blade stirring mechanism 10301 is located at 2 / 3 to 3 / 5 of the height of the bottom of the mixing tank 105, and includes two straight blades with a diameter of 0.6d1 to 0.7d1. The lower turbine blade stirring mechanism 10302 is located at 1 / 3 to 2 / 5 of the height of the bottom of the mixing tank 105, and includes a disc and multiple turbine blades embedded around the disc. The total diameter of the lower turbine blade stirring mechanism 10302 is 0.8d1, wherein the diameter of the disc is 0.5d1 to 0.6d1, and the blade length is 0.5d1 to 0.6d1. Preferably, the turbine blades of the lower turbine blade stirring mechanism 10302 are 45° six-bladed. The turbine blades of the lower turbine blade stirring mechanism 10302 axially lift the water flow, while the two straight blades of the upper straight blade stirring mechanism 10301 have a radial effect on the water flow. When the water flow moves vertically under the action of the turbine blades, the two straight blades radially diffuse the water flow, enabling the water flow and the agent to diffuse and mix rapidly.

[0049] Water enters the mixing zone between two partition plates 102 through the inlet 101 of the mixing tank. Under the stirring action of the agitator 103 in the mixing zone, the agent is fully diffused and mixed evenly. Then, it flows up through the gap between the partition plate 102 and the bottom of the mixing tank 105 to the outlet at the top of the mixing tank 105 and flows out of the mixing tank 105.

[0050] Flocculation zone 2 includes a flocculation tank 205, a central cylinder 203, and a flocculation zone agitator 204. The central cylinder 203 is placed inside the flocculation tank 205 (in the later stage of the flocculation reaction, the overall turbulence of the water flow should not be too high to avoid the breakage of the formed flocs, hence the central cylinder 203 is installed inside the flocculation zone 2), and the flocculation zone agitator 204 is placed inside the central cylinder 203. Flocculation zone 2 adopts a bottom-inlet and bottom-outlet design, with water entering through a pipe and exiting through submerged orifices; that is, the inlet 201 of the flocculation tank is located at the bottom of the central cylinder 203 and is connected to the outlet 104 of the mixing tank through the first outlet pipe 5; the outlet 202 of the flocculation tank is located at the lower part of the flocculation tank 205 and outside the central cylinder 203. Water enters the central cylinder 203 through the first outlet pipe 5. Under the action of the agitator 204 in the flocculation zone, the substances and agents in the incoming water further react to form flocs. Outside the central cylinder 203, where there is no agitator 204, the water flow turbulence decreases, providing an environment for further floc growth. After passing through the central cylinder 203, the water flows downwards to the outlet 202 of the flocculation tank and out of the flocculation zone 2. The agitator 204 in the flocculation zone includes a lower blade agitator 20402 and an upper blade agitator 20401 arranged sequentially from bottom to top. The diameter d2 of the central cylinder 203 is 0.5 to 0.7 times the side length of the flocculation tank 205. The lower blade agitator 20402 is 1 / 2 to 3 / 5 of the height of the bottom of the flocculation tank 205, and the upper blade agitator 20401 is 3 / 4 to 4 / 5 of the height of the bottom of the flocculation tank 205. Both the lower blade stirring mechanism 20402 and the upper blade stirring mechanism 20401 adopt 45° four oblique blades with a total diameter of 0.9d2.

[0051] The sedimentation zone 3 uses a submerged orifice for water inlet and an overflow weir for water outlet to avoid negative impacts on the sedimentation process. It includes a sedimentation tank 309. From bottom to top, sedimentation tank 309 consists of a sludge settling zone 302, a lower inclined plate zone 303, a water distribution zone 304, a suspended solids interception zone 305, an upper inclined plate zone 306, and an outlet zone 307. The inlet of the sedimentation tank is located at the top of sedimentation tank 309 and is connected to the outlet 202 of the flocculation tank via the inlet zone 301. The sludge settling zone 302 is connected to the outlet 202 of the flocculation zone via a circulating water pump 4. An online suspended solids concentration measuring instrument 308 is installed in the suspended solids interception zone 305. To reduce short-circuiting and maximize the sedimentation effect of the inclined plates, the inclined plates in the lower inclined plate zone 306 and the upper inclined plate zone 303 have different inclination directions. During the start-up phase, circulating water pump 4 circulates the sludge settled in the sedimentation zone 302 to the inlet water zone 301, and then into the sedimentation zone 3 to cultivate the suspended layer in the suspended interception zone 305. When the suspended solids concentration in the suspended interception zone 305 reaches 3-10 g / L, circulating water pump 4 is stopped. After the specified concentration is reached, the normal treatment phase begins.

[0052] In this embodiment, to avoid negative impacts of influent and effluent on the sedimentation process, the height of the effluent zone 307 must not be less than 0.8m. To ensure sedimentation effectiveness, the incoming water needs to be evenly distributed after entering the sedimentation zone 3; therefore, the height of the water distribution zone 304 must not be less than 1.5m. A suspended layer is formed in the suspended interception zone 305 by controlling the flow velocity variation. The ratio of the lower to upper water flow area of ​​the suspended interception zone 305 is 1:1.2 to 1:1.5, and the height of the suspended interception zone 305 must not be less than 1.0m.

[0053] In this embodiment, the height of the upper inclined plate area 306 is 0.8~1.0m, and it is formed by multiple flat plates installed at an angle. The inclination angle of the flat plates is 60°; the spacing between adjacent flat plates is 80~100mm. The height of the lower inclined plate area is 0.8~1.0m, and it is formed by multiple corrugated plates installed at an angle. The inclination angle of the corrugated plates is 60°. The wavelength of the corrugated plates is 400~500mm, and the wave height is 80~100mm; the spacing between adjacent corrugated plates is 150~300mm. The inclination directions of the flat plates and the corrugated plates are different, that is, the installation directions of the upper inclined plate area 306 and the lower inclined plate area 303 are different.

[0054] In this embodiment, the hydraulic retention time of the self-renewing high-density sedimentation tank with suspended layer is 40 min to 60 min; wherein, the hydraulic retention time of mixing zone 1 shall not exceed 2 min, the hydraulic retention time of flocculation zone 2 shall be 15 min to 20 min, and the hydraulic retention time of sedimentation zone 3 shall be 30 min to 45 min.

[0055] Specific examples:

[0056] The water sample used common kaolin as the suspended solids had an influent concentration of 3 g / L, a particle density of 1010 kg / m³, and an average particle size of 100 µm. The treatment effect of a conventional high-density sedimentation tank was compared with that of this invention. The parameters of the conventional high-density sedimentation tank, such as volume, treatment capacity, influent and effluent velocities, G-value in the mixing zone and flocculation zone, and upward flow velocity in the sedimentation zone, were consistent with those of this invention.

[0057] Figure 5 These are comparison images showing the treatment effects of a conventional high-density sedimentation tank and the present invention at different times. Figure 5It is evident that the increase in the concentration of suspended solids at the outlet of the present invention over time is slower than that of a conventional high-density sedimentation tank, and the decrease in the removal rate over time is also slower. Conventional high-density sedimentation tanks exhibit excellent performance in removing suspended solids within the first 2 hours; however, as time progresses, the concentration of suspended solids at the outlet rises rapidly. This is because, at the beginning of the working cycle, no suspended solids accumulate in the sedimentation zone, making them easier to settle and remove in the reactor. However, as time passes, suspended solids settle in the reaction tank and migrate towards the outlet, resulting in an increase in the amount of suspended solids at the outlet. The original high-density sedimentation tank had limited interception capacity for suspended solids, thus resulting in good initial interception but quickly reaching the limit of its interception capacity. In contrast, the high-density sedimentation tank provided by the present invention, due to its more rational flow field and enhanced interception capacity for suspended solids, exhibits a slower change in the concentration of suspended solids at the outlet over time compared to conventional high-density sedimentation tanks, naturally leading to a significantly higher removal rate of suspended solids within the same working cycle.

[0058] The incoming water and the reagent are rapidly mixed in the mixing zone 1 by the mixing zone agitator 103 and then enter the flocculation zone 2. The incoming water in the mixing zone 1 passes through the central cylinder 203 and is stirred at low speed by the flocculation zone agitator 204, which causes further reaction and the flocs gradually increase in size. After the incoming water passes through the central cylinder 203, the water flow disturbance outside the central cylinder 203 is small, and the flocs further increase in size before entering the sedimentation zone 3. The suspension interception zone 305 of the sedimentation zone 3 forms a dynamic suspension layer that can be automatically renewed through changes in flow velocity. After the incoming water in the flocculation zone 2 passes through the sedimentation zone 3, the flocs are intercepted and removed.

[0059] The rapid mixing in the mixing zone and the flocculation zone provide an excellent environment for floc formation and growth, laying the foundation for the formation and dynamic renewal of the subsequent suspended interception zone 305 (suspended layer). Due to the variable speed and double-layer inclined plates in the suspended interception zone 305, the suspended layer can achieve dynamic self-renewal. Compared with traditional high-density sedimentation tanks, sludge recirculation is unnecessary, and the double-layer inclined plates and suspended interception zone further improve the floc removal rate. Therefore, while reducing costs, the effluent quality is significantly improved.

[0060] Example 2

[0061] A water treatment method, employing the self-renewing high-density sedimentation tank with suspended layer as described in Example 1, includes the following steps:

[0062] Incoming water and coagulant are rapidly and thoroughly stirred in mixing zone 1; after the pollutants and agents in the incoming water are fully mixed, they enter flocculation zone 2 to react and generate flocs; the flocs enter sedimentation zone 3.

[0063] During the start-up phase, the suspended solids layer in the suspended interception zone 305 of the sedimentation zone 3 needs to be cultivated. Specifically, during the start-up phase, the circulating water pump 4 circulates the settled sludge from the sedimentation zone 302 of the sedimentation zone to the outlet 202 (inlet zone 301) of the flocculation zone to cultivate the suspended solids layer in the suspended interception zone 305. When the suspended solids concentration in the suspended interception zone 305 reaches 3-10 g / L, the circulating water pump 4 is stopped, and the treatment phase begins. If the suspended solids concentration in the suspended interception zone 305 does not meet the requirements during the treatment phase, the circulating water pump 4 is turned on until the required concentration is reached, and then turned off.

[0064] After entering the sedimentation zone 3, the flocs flow upward to the lower inclined plate zone 303. Some of the larger suspended solids settle in the lower inclined plate zone 303. Due to the aggregation effect of the troughs of the corrugated plates on the suspended solids, the suspended solids settle and compress at the troughs, forming a larger and denser floc structure. After accumulating and compressing to a certain extent, they slide down to the sludge zone 302 at the bottom of the sedimentation tank 309. Because of the increased particle size and density, this type of floc has a stronger resistance to the upward water flow and is more likely to settle quickly at the bottom of the sedimentation tank 309 and is not easily rolled up. The smaller suspended solids then reach the suspended solids interception zone 305 through the lower inclined plate zone 303.

[0065] Due to the presence of the suspended layer in the suspended interception zone 305, some suspended matter is intercepted and adsorbed, resulting in contact flocculation, which increases the particle size and density. Subsequently, it flows against the direction of water flow and slides down to the lower inclined plate zone 303 to be removed; the other part continues to flow upward with the water flow to the upper inclined plate zone 306.

[0066] A portion of the sludge settles in the upper inclined plate zone 306 and slides down to the suspended interception zone 305, promoting the autonomous dynamic renewal of the suspended layer in the suspended interception zone 305. Due to the presence of the suspended layer in the lower inclined plate zone 303 and the suspended interception zone 305, the sedimentation tank 309 enhances its interception effect on suspended solids, and the contact flocculation effect is effectively utilized. This allows the sludge to finally settle in the sludge settling zone 302 of the sedimentation zone 3 without external sludge return, thanks to the presence of carrier flocculation and the dynamic renewal of the sludge suspended layer. The treated water flows out from the effluent zone 307 at the top of the sedimentation tank 309, greatly improving the removal efficiency of small flocs in the sedimentation tank and solving the sludge clogging problem, resulting in better effluent quality.

[0067] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0068] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A water treatment method, characterized in that: The method employs a self-renewing high-density sedimentation tank with a suspended layer; the self-renewing high-density sedimentation tank with a suspended layer includes a mixing zone, a flocculation zone, and a sedimentation zone arranged sequentially. The mixing zone includes a mixing tank and a mixing zone agitator located within the mixing tank. The mixing zone agitator includes a lower turbine blade agitation mechanism and an upper straight blade agitation mechanism arranged sequentially from bottom to top. The flocculation zone includes a flocculation tank, a central cylinder, and a flocculation zone agitator; the central cylinder is placed inside the flocculation tank, and the flocculation zone agitator is placed inside the central cylinder; the flocculation zone agitator includes a lower blade agitator and an upper blade agitator arranged sequentially from bottom to top. The sedimentation zone includes a sedimentation tank; the sedimentation tank, from bottom to top, consists of a sludge settling zone, a water distribution zone, a lower inclined plate zone, a suspended solids interception zone, an upper inclined plate zone, and an effluent zone; the inlet of the sedimentation tank is located at the top of the sedimentation tank and is connected to the effluent outlet of the flocculation tank through the inlet zone; the sludge settling zone is connected to the inlet zone via a circulating water pump; an online suspended solids concentration measuring instrument is installed in the suspended solids interception zone; the inclined plates in the lower and upper inclined plate zones have different inclination directions; The upper inclined plate area is formed by multiple flat plates installed at an angle; the inclination angle of the flat plates is 50-70°; the spacing between adjacent flat plates is 80-100mm; the height of the upper inclined plate area is 0.8-1.0m. The lower inclined plate area is formed by multiple corrugated plates installed at an angle; the wavelength of the corrugated plates is 400-500mm, and the wave height is 80-100mm; the inclination angle of the corrugated plates is 50-70°; the spacing between adjacent corrugated plates is 150-300mm; the height of the lower inclined plate area is 0.8-1.0m; the flat plates and corrugated plates have different inclination directions. The height of the outlet zone shall not be less than 0.8m; the height of the distribution zone shall not be less than 1.5m; the suspended interception zone shall be controlled by flow velocity changes to form a suspended layer; the height of the suspended interception zone shall not be less than 1.0m; the ratio of the lower water flow area to the upper water flow area of ​​the suspended interception zone shall be 1:1.2 to 1:1.

5. The method includes the following steps: The incoming water and coagulant are rapidly and thoroughly mixed in the mixing zone; after the pollutants and agents in the incoming water are fully mixed, they enter the flocculation zone to react and generate flocs; the flocs then enter the sedimentation zone. During the start-up phase, the suspended layer in the suspended interception zone of the sedimentation zone needs to be cultivated. Specifically, during the start-up phase, the circulating water pump circulates the settled sludge from the sedimentation zone to the outlet of the flocculation zone. When the suspended solids concentration in the suspended interception zone reaches 3-10 g / L, the circulating water pump is stopped, and the treatment phase begins. If the suspended layer concentration in the suspended interception zone does not meet the requirements during the treatment phase, the circulating water pump is turned on until the required concentration is reached, and then turned off. After entering the sedimentation zone, the flocs flow upwards to the lower inclined plate zone. Some of the larger suspended solids settle in the lower inclined plate zone. Due to the aggregation effect of the troughs of the corrugated plates, the suspended solids settle and compress at the troughs, forming a larger and denser floc structure. After accumulating and compressing to a certain extent, they slide down to the sludge zone at the bottom of the sedimentation tank. Because of their increased particle size and density, these flocs have a stronger resistance to being carried up by the upward water flow, making them easier to settle quickly at the bottom of the sedimentation tank and less likely to be rolled up. The smaller suspended solids then move upwards through the lower inclined plate zone to reach the suspension interception zone. Due to the presence of the suspended layer in the suspended interception zone, some suspended matter is intercepted and adsorbed, resulting in contact flocculation, which increases the particle size and density. Subsequently, it flows against the direction of water flow and slides down to the lower inclined plate zone to be removed; the other part continues to flow upward with the water flow to the upper inclined plate zone. A portion of the sludge settles in the upper inclined plate zone and slides down to the suspended interception zone, promoting the autonomous dynamic renewal of the suspended layer in the suspended interception zone. Due to the presence of the lower inclined plate zone and the suspended layer in the suspended interception zone, the sedimentation tank enhances its interception of suspended solids, and the contact flocculation effect is effectively utilized. This allows the sludge to eventually settle in the sedimentation zone of the sedimentation tank without external sludge return, thanks to the presence of carrier flocculation and the dynamic renewal of the sludge suspended layer. The treated water flows out from the effluent area at the top of the sedimentation tank.

2. The water treatment method according to claim 1, characterized in that: The hydraulic retention time of the self-renewing high-density sedimentation tank with suspended layer is 40 min to 60 min; wherein, the hydraulic retention time in the mixing zone shall not exceed 2 min, the hydraulic retention time in the flocculation zone shall be 15 min to 20 min, and the hydraulic retention time in the sedimentation zone shall be 30 min to 45 min.

3. The water treatment method according to claim 1, characterized in that: The mixing tank is divided into three areas by two parallel partition plates. The upper end of the partition plates is connected to the top of the mixing tank, and the lower end is separated from the bottom of the mixing tank. The agitator of the mixing zone is placed between the two partition plates. The water inlet of the mixing tank is located at the top of the mixing tank and between the two partition plates. The mixing tank has two water outlets, located at the top of the mixing tank and outside the two partition plates. Water enters the mixing zone between two partition plates through the inlet of the mixing tank. Under the stirring action of the agitator in the mixing zone, the agent is fully diffused and mixed evenly. Then, it flows up through the gap between the partition plate and the bottom of the mixing tank and flows out of the mixing tank through the outlet.

4. The water treatment method according to claim 3, characterized in that: The distance between the two partition plates is d1; The upper straight-blade stirring mechanism is located 2 / 3 to 3 / 5 of the mixing tank height from the bottom of the mixing tank, and includes two straight blades; the diameter of the straight blades is 0.6d1 to 0.7d1; The lower turbine blade stirring mechanism is located at 1 / 3 to 2 / 5 of the height of the mixing tank from the bottom of the mixing tank. It includes a disc and multiple turbine blades embedded around the disc. The total diameter of the lower turbine blade stirring mechanism is 0.8d1, wherein the diameter of the disc is 0.5d1 to 0.6d1, and the blade length is 0.5d1 to 0.6d1.

5. The water treatment method according to claim 1, characterized in that: The inlet of the flocculation tank is located at the bottom of the central cylinder and is connected to the outlet of the mixing tank through the first outlet pipe; the outlet of the flocculation tank is located at the lower part of the flocculation tank and outside the central cylinder.

6. The water treatment method according to claim 1, characterized in that: The diameter d2 of the central cylinder is 0.5 to 0.7 times the side length of the flocculation tank.

7. The water treatment method according to claim 6, characterized in that: The lower blade agitator is positioned 1 / 2 to 3 / 5 of the height of the flocculation tank bottom, while the upper blade agitator is positioned 3 / 4 to 4 / 5 of the height of the flocculation tank bottom. Both the lower and upper blade agitators use 45° four-bladed blades with a total diameter of 0.9d2.

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