A sewage treatment system and method

Abstract

The application discloses a sewage treatment system and method, belongs to the technical field of sewage treatment, can reduce the risk of grease wrapping biological filler in the subsequent biological treatment unit, and improves the effluent water quality stability and treatment efficiency of the overall sewage treatment system. The sewage treatment system comprises a sewage treatment tank, the sewage treatment tank comprises a sewage treatment pool, a water inlet pipeline and a drain pipeline, the water inlet pipeline and the drain pipeline are arranged on opposite sides of the sewage treatment pool and are in communication with the inside of the sewage treatment pool, the sewage treatment pool comprises an oil-water separation zone, an overflow zone and a drainage zone, two groups of overflow plates are arranged between the oil-water separation zone and the adjacent overflow zone and between the adjacent overflow zones, the two groups of overflow plates are arranged in an upper and lower staggered mode, the drainage zone and the adjacent overflow zone thereof are separated by one group of overflow plates, the bottom of the overflow plate arranged between the drainage zone and the adjacent overflow zone thereof and the bottom of the sewage treatment pool form a communication port, and an oil outlet is arranged on the upper portion of the oil-water separation zone.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a wastewater treatment system and method. Background Technology

[0002] Wastewater discharged from food processing plants contains a large amount of animal and vegetable oils, suspended solids, and organic pollutants. If it enters the treatment system directly, the oils will easily adhere to the surface of the biological packing material to form a coating layer, which will reduce the activity of microorganisms. Suspended solids will increase the load on subsequent treatment units, causing problems such as sludge bulking, and ultimately affecting the stability of the effluent quality.

[0003] Currently, the most common pretreatment methods in the industry employ a combination of bar screen filtration and grease traps. However, this approach has the following drawbacks: bar screens can only remove large-diameter suspended solids, and their effectiveness in intercepting emulsified grease is limited. Although some users currently employ conveyor belt-mounted oil skimming systems to remove surface oil from wastewater, during the treatment of food wastewater, the oil migrates with the water flow and re-aggregates in different areas. Even after treatment by the conveyor belt-mounted oil skimming system, a significant amount of oil still enters subsequent treatment units. Summary of the Invention

[0004] Therefore, in order to address the above-mentioned shortcomings, the present invention provides a wastewater treatment system and method to reduce the risk of grease encapsulation of biological packing material in subsequent biological treatment units, and to improve the effluent quality stability and treatment efficiency of the overall wastewater treatment system.

[0005] On one hand, the present invention provides a wastewater treatment system, including a wastewater treatment tank. The wastewater treatment tank includes a wastewater treatment pool, an inlet pipe, and a drain pipe. The inlet pipe and the drain pipe are respectively located on opposite sides of the wastewater treatment pool and are connected to the interior of the wastewater treatment pool. The wastewater treatment pool, from the side with the inlet pipe to the side with the drain pipe, sequentially includes an oil-water separation zone, an overflow zone, and a drainage zone. Multiple overflow zones are provided, and two overflow zones are provided between each oil-water separation zone and adjacent overflow zones, as well as between adjacent overflow zones. Two overflow plates extend vertically along the height of the sewage treatment tank and are fixed to the inner walls of opposite sides of the tank. The two overflow plates are staggered vertically to form an overflow channel. Sewage from the lower layer of the oil-water separation zone or overflow zone enters the overflow channel from the bottom and overflows from the top to the adjacent overflow zone. The drainage zone is separated from the adjacent overflow zone by a set of overflow plates. The bottom of the overflow plate located between the drainage zone and the adjacent overflow zone forms a communication port with the bottom of the sewage treatment tank. An oil discharge port is provided at the top of the oil-water separation zone.

[0006] Furthermore, heaters are provided in both the oil-water separation zone and the overflow zone.

[0007] Furthermore, the wastewater treatment system also includes a scraper module, which is fixedly mounted on the upper part of the wastewater treatment tank.

[0008] The scraper module includes:

[0009] The first turntable is located at the upper part of the overflow area and is driven to rotate by the first power device.

[0010] The second turntable is located above the oil-water separation zone and is driven to rotate by the second power device.

[0011] The scraper is inclined as a whole, and the upper surface of the scraper is recessed inward to form an oil guide groove. The oil guide groove is arranged along the extension direction of the scraper, and one side of the scraper is in contact with the surface of the first turntable or the second turntable.

[0012] The oil drain trough is inclined as a whole, and the maximum height of the oil drain trough is located below the lowest height of the scraper.

[0013] Furthermore, the wastewater treatment system also includes a filtration module, which is installed below the outlet end of the inlet pipe.

[0014] Furthermore, the filtering module includes:

[0015] Belt filter;

[0016] Wastewater collection tank is located between the filter cloth bearing section and the transition section of the belt filter. A drain outlet communicating with the oil-water separation zone is provided on the lower side of the wastewater collection tank.

[0017] Furthermore, the filtration module also includes a baffle plate, which surrounds the surface of the filter mesh support section. The water outlet of the inlet pipe is located within the area surrounded by the baffle plate, and the baffle plate has a slag outlet near the discharge end of the belt filter.

[0018] Furthermore, the belt filter has a vertical section extending downward in the middle region of the filter mesh transition section;

[0019] The wastewater treatment system also includes a filter cake collection box, which comprises:

[0020] The housing is positioned entirely below the discharge end of the belt filter.

[0021] The slag scraper is inclinedly installed inside the box, with one side of the scraper contacting the side of the vertical section near the discharge end of the belt filter.

[0022] Furthermore, the wastewater treatment system also includes:

[0023] The data acquisition module is used to obtain the oil layer thickness, water flow rate, and filter residue thickness in the oil-water separation zone.

[0024] The control module is used to acquire the inlet water flow rate and filter cake thickness, calculate the travel speed of the filter belt in the belt filter based on the inlet water flow rate and filter cake thickness, adjust the travel speed of the filter belt based on the calculation result, acquire the oil layer thickness in the oil-water separation zone, determine oil discharge based on the oil layer thickness in the oil-water separation zone, and activate the scraper module and / or the oil discharge port based on the oil discharge determination result.

[0025] Furthermore, the specific method for activating the scraper module and / or the oil drain port based on the oil drain judgment result is as follows:

[0026] When the oil layer thickness in the oil-water separation zone is greater than or equal to the first threshold, the valve controlling the oil drain port is fully opened, and the second power unit is controlled or kept stopped.

[0027] When the oil layer thickness in the oil-water separation zone is less than the first threshold and greater than the second threshold, the rotation speed of the second turntable and the valve opening of the oil outlet are calculated based on the oil layer thickness. The output of the second power unit is controlled based on the calculation result of the rotation speed of the second turntable, and the valve of the oil outlet is controlled to open at the preset opening based on the calculation result of the valve opening of the oil outlet.

[0028] When the oil layer thickness in the oil-water separation zone is less than or equal to the second threshold, the control oil drain port is completely closed, and the second power unit is started to run at a preset speed;

[0029] Wherein, the first threshold is greater than the second threshold.

[0030] On the other hand, the present invention also provides a wastewater treatment method, which is executed by the aforementioned wastewater treatment system, the wastewater treatment method comprising:

[0031] When the equipment is started, the filter belt of the belt filter moves continuously at an initial speed. Wastewater is injected through the inlet pipe and filtered by the filter belt. Solid waste is trapped and forms filter cake, which remains on the surface of the filter belt. As the filter belt moves to the outlet, it falls into the filter cake collection box under the action of gravity. The filter cake attached to the filter belt is scraped off by the scraper in the transition section and falls into the filter cake collection box. The filtrate flows through the belt into the wastewater collection tank below, and then enters the oil-water separation zone of the sewage treatment tank through the drain outlet. The control module obtains the inlet flow rate and filter cake thickness in real time, calculates the traveling speed of the filter belt in the belt filter based on the inlet flow rate and filter cake thickness, and adjusts the traveling speed of the filter belt based on the calculation results.

[0032] The wastewater entering the oil-water separation zone, under the assistance of settling and heater, gradually causes the grease to float to the surface and form an oil layer. When the wastewater rises to a preset height, the control module obtains the oil layer thickness in the oil-water separation zone in real time, and makes an oil discharge judgment based on the oil layer thickness in the oil-water separation zone. Based on the oil discharge judgment result, the scraper module and / or the oil discharge port are activated.

[0033] Wastewater in the lower layer of the oil-water separation zone enters the adjacent overflow zone through the overflow channel and remains there. The remaining trace amount of floating oil floats to the surface. When the waste liquid rises to a preset height, the first power device drives the first turntable to rotate continuously. The floating oil on the liquid surface is adhered to the surface of the first turntable. As the first turntable continues to rotate, the grease-adhered turntable surface passes through a fixed inclined scraper. The edge of the scraper keeps in contact with the surface of the first turntable, continuously scraping off the grease layer adhering to the surface of the first turntable. The scraped grease is collected along the oil guide groove and guided to its lowest point by gravity, and finally drips into the oil discharge groove set below. Wastewater flows through the same overflow plate channel structure in sequence through the subsequent overflow zones, repeating the above oil removal process.

[0034] The lower layer of sewage from the overflow zone of the adjacent drainage zone enters the drainage zone through the bottom connection, while the upper layer of sewage in the drainage zone is discharged from the system through the drainage pipe.

[0035] The present invention has the following advantages:

[0036] In this invention, as the wastewater height in the oil-water separation zone or overflow zone rises, the wastewater in the overflow channel rises synchronously. Since the cross-sectional area of ​​the overflow channel is much smaller than that of the oil-water separation zone / overflow zone, before the wastewater height reaches the maximum height of the overflow channel inlet, only a very small amount of floating oil accumulated in the upper part of the oil-water separation zone / overflow zone can enter the channel; most of the floating oil is retained in the original treatment area. When the wastewater height rises above the maximum height of the overflow channel inlet, because the floating oil accumulates on the wastewater surface, it cannot enter the overflow channel due to the obstruction of the overflow plate. Only low-oil-content or oil-free wastewater from the lower layer is allowed to enter the channel. After each overflow, the oil content of the wastewater entering the next zone is lower than that of the previous zone. This process continues in subsequent overflow zones, and after multiple overflow zones, the oil content of the wastewater will continuously decrease to a lower level. Ultimately, when the wastewater enters the drainage area, its oil content is much lower than that of the wastewater treated by the existing pretreatment process. This reduces the risk of grease encapsulating the biological packing material in the subsequent biological treatment unit and improves the effluent quality stability and treatment efficiency of the overall wastewater treatment system. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the wastewater treatment system;

[0038] Figure 2 yes Figure 1 The diagram shows the internal structure of the wastewater treatment system.

[0039] Figure 3 yes Figure 1 The diagram shows the structure of a belt filter in a wastewater treatment system.

[0040] Figure 4 yes Figure 1 The diagram shows the structure of the filter cake collection box in the wastewater treatment system.

[0041] Figure 5 yes Figure 2 A schematic diagram of the scraper module in the wastewater treatment system shown.

[0042] Figure 6 yes Figure 5 An enlarged schematic diagram of a portion of structure A in the scraper module shown;

[0043] Figure 7 yes Figure 1 The diagram shows the control logic of the wastewater treatment system.

[0044] In the picture:

[0045] 100. Wastewater treatment tank; 110. Tank body; 120. Inlet pipe; 130. Drainage pipe; 140. Heater; 150. Wastewater treatment pool; 151. Oil-water separation zone; 152. Overflow zone; 153. Overflow channel; 154. Drainage zone; 155. Oil drain port; 160. Overflow plate;

[0046] 200. Filter module; 210. Belt filter; 220. Water baffle; 230. Wastewater collection tank; 231. Drain outlet;

[0047] 300. Filter residue collection box; 310. Box body; 320. Sludge scraper;

[0048] 400, Scraper module; 410, First power unit; 420, Fixing plate; 421, Turntable groove; 430, Oil drain groove; 440, First turntable; 450, Second turntable; 460, Second power unit; 470, Scraper; 471, Oil guide groove;

[0049] 500. Control module;

[0050] 600. Data Acquisition Module. Detailed Implementation

[0051] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0052] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0053] As described in the background section, during the treatment of food wastewater, floating oil migrates with the water flow and re-aggregates in different areas. Even after treatment by the tracked oil skimming system, a significant amount of floating oil still enters the subsequent treatment units.

[0054] Example 1:

[0055] Therefore, in order to solve the above-mentioned technical problems existing in the prior art, this embodiment provides a sewage treatment system, such as... Figure 1 , 2 As shown, the wastewater treatment system includes a wastewater treatment tank 100, which comprises a wastewater treatment pool 150, an inlet pipe 120, and a drain pipe 130. The inlet pipe and the drain pipe are respectively located on opposite sides of the wastewater treatment pool and are connected to the interior of the wastewater treatment pool. The wastewater treatment pool, from the side with the inlet pipe to the side with the drain pipe, sequentially includes an oil-water separation zone 151, an overflow zone 152, and a drainage zone 154. There are multiple overflow zones, and a separation device is provided between the oil-water separation zone and adjacent overflow zones, as well as between adjacent overflow zones. There are two sets of overflow plates 160, both of which extend vertically along the height of the sewage treatment tank and are fixed to the inner walls of opposite sides of the sewage treatment tank. The two sets of overflow plates are staggered vertically to form an overflow channel. The lower layer of sewage in the oil-water separation zone or overflow zone enters the overflow channel from the bottom and overflows from the top to the adjacent overflow zone. The drainage zone and its adjacent overflow zone are separated by a set of overflow plates. The bottom of the overflow plate located between the drainage zone and its adjacent overflow zone forms a communication port with the bottom of the sewage treatment tank. An oil discharge port 155 is provided at the top of the oil-water separation zone.

[0056] Specifically, the wastewater treatment tank also includes a tank body 110, in which the wastewater treatment pool is fixedly located. Additionally, rollers can be installed at the bottom of the tank body, and an inspection port is provided at the top. In this embodiment, wastewater containing a large amount of animal and vegetable oils and suspended solids discharged from the food processing plant first enters the oil-water separation zone through an inlet pipe located on one side of the wastewater treatment pool. During the time the wastewater remains in the oil-water separation zone, because oil has a lower density than water, it will naturally float to the surface of the wastewater, forming an oil layer, while the suspended solids will gradually settle to the lower layer of the wastewater due to gravity. As wastewater continues to be injected, the waste liquid level in the oil-water separation zone gradually rises. Based on the principle of communicating vessels, the waste liquid in the overflow channel between this zone and the adjacent overflow zone rises synchronously. Because the cross-sectional area of ​​the overflow channel is much smaller than that of the oil-water separation zone, only a very small amount of floating oil enters the channel before the waste liquid height reaches the maximum height of the overflow channel inlet (the gap between the bottom of the overflow plate and the bottom of the pool). Most of the floating oil remains in the oil-water separation zone. When the waste liquid height exceeds the maximum height of the inlet, the surface floating oil is physically blocked by the overflow plate and cannot enter the channel. Only the low-oil-content wastewater from the lower layer of the oil-water separation zone enters the overflow channel from the inlet and overflows from the top of the channel to the adjacent first overflow zone. The low-oil-content wastewater entering the first overflow zone will repeat the settling and separation process of the oil-water separation zone. As the waste liquid height in the first overflow zone rises, the overflow channel between it and the next overflow zone is also based on the principle of communicating vessels and the difference in cross-sectional area. The surface residual floating oil is blocked by the overflow plate, and only the lower layer of even lower-oil-content wastewater enters the second overflow zone through the overflow channel. Following this logic, wastewater flows sequentially through multiple overflow zones, with the oil content decreasing progressively with each overflow (from initially high oil content to trace amounts), while suspended solids are continuously separated to the bottom of the tank through multi-stage sedimentation. Wastewater treated in the final overflow zone enters the drainage zone through the connection between this overflow zone and the drainage zone. The drainage zone serves as the final wastewater buffer and collection area, where the wastewater undergoes a final settling and stabilization process before being discharged through a drainage pipe located on the other side of the wastewater treatment tank, proceeding to subsequent biological treatment units. At this point, the discharged wastewater has a significantly lower oil content than the effluent from existing pretreatment processes, effectively mitigating the problem of oil-coated biological packing materials in subsequent biological treatment. It also reduces the load of suspended solids on subsequent units, ensuring the stable operation of the overall wastewater treatment system and guaranteeing effluent quality compliance.

[0057] like Figure 2 As shown, heaters 140 are provided in both the oil-water separation zone and the overflow zone.

[0058] Specifically, since animal fats (such as lard and beef) and some vegetable fats (such as coconut oil and cocoa butter) solidify into lumps at lower temperatures, and the lumps of fat are difficult to discharge from the drain or be carried out by the scraper, the wastewater can be heated by a heater during the wastewater treatment process to keep it at a higher temperature, so that the fat remains in a liquid state.

[0059] like Figure 2 As shown, the wastewater treatment system also includes a scraper module 400, which is fixedly mounted on the upper part of the wastewater treatment tank.

[0060] like Figure 5 As shown, the scraper module includes:

[0061] The first turntable 440 is located at the upper part of the overflow area and is driven to rotate by the first power device.

[0062] The second turntable 450 is located above the oil-water separation zone and is driven to rotate by the second power device.

[0063] Scraper 470, the scraper is set at an overall angle, such as Figure 6 As shown, the upper surface of the scraper is recessed inward to form an oil guide groove 471, which is arranged along the extension direction of the scraper, and one side of the scraper is in contact with the surface of the first turntable or the second turntable.

[0064] The oil drain trough 430 is inclined as a whole, and the maximum height of the oil drain trough is located below the lowest height of the scraper.

[0065] Specifically, the scraper module may further include a fixing plate 420, which is fixedly mounted on the upper part of the sewage treatment tank. The first power unit and the second power unit are fixedly mounted on the fixing plate. The first turntable and the second turntable are rotatably mounted on the fixing plate via a rotating shaft. The rotating shaft axes of the first turntable and the second turntable are on the same axis. A turntable groove 421 is provided on the surface of the fixing plate. The first turntable or the second turntable extends from below the fixing plate through the turntable groove to above the fixing plate. The scraper is fixed on both sides of the turntable groove parallel to the first turntable or the second turntable. The side with the maximum height of the oil discharge groove is fixedly connected to the fixing plate. The second power unit starts, driving the second turntable to rotate. Floating oil on the liquid surface adheres to the surface of the second turntable. As the second turntable continues to rotate, the grease-coated surface is scraped away by a fixed, inclined scraper, the edge of which remains in contact with the turntable surface. The scraped grease collects along the oil guide channel and is guided by gravity to its lowest point, eventually dripping into the lower oil discharge channel. After the wastewater enters the overflow area, the first power unit starts, driving the first turntable to rotate. Similar to the oil scraping method in the oil-water separation zone, the floating oil in the oil discharge channel flows under gravity along the channel's extension direction towards its lowest point, ultimately being discharged from the end of the channel to subsequent grease treatment equipment.

[0066] In this embodiment, as Figure 2 As shown, the wastewater treatment system also includes a filter module 200, which is installed below the outlet end of the inlet pipe.

[0067] like Figure 3 As shown, the filtering module includes:

[0068] Belt filter 210;

[0069] Wastewater collection tank 230 is located between the filter cloth bearing section and the transition section of the belt filter. A drain outlet 231 communicating with the oil-water separation zone is provided on the lower side of the wastewater collection tank.

[0070] The belt filter is fixed at the top of the oil-water separation zone in the wastewater treatment tank. Wastewater from the food processing plant, containing a large amount of suspended solids (such as food scraps, colloidal particles, and debris) and grease, is first introduced into the belt filter fixed at the top of the oil-water separation zone before entering the separation zone. After the belt filter is started, its built-in filter cloth (with an appropriate pore size selected according to the particle size of the suspended solids in the wastewater, such as 50-100 mesh) moves along the transmission mechanism. When the wastewater is evenly distributed on the filter cloth bearing section of the belt filter, large suspended solids (such as food scrap fragments) and some small suspended solids (such as colloidal aggregates) in the wastewater are blocked on the surface of the filter cloth. The filtered water (still containing grease) after the suspended solids are removed seeps out from the mesh of the filter cloth due to gravity and flows to the wastewater collection tank. After a brief buffer in the collection tank, the filtered water flows into the oil-water separation zone below through the drain outlet. At this point, the filtered water returned to the oil-water separation zone has had most of the suspended solids removed, reducing the impurity load on subsequent treatments in the oil-water separation zone and improving the overall pretreatment efficiency.

[0071] In addition, the filter module also includes a baffle plate 220, which surrounds the surface of the filter mesh support section. The water outlet of the water inlet pipe is located within the area surrounded by the baffle plate, and the baffle plate has a slag outlet near the discharge end of the belt filter.

[0072] The baffle plate confines the wastewater discharged from the inlet pipe within the effective filtration range of the filter mesh support section, reducing the risk of wastewater splashing out of the support section or flowing into non-filtration areas due to inlet water impact, thus improving wastewater retention rate and filtration efficiency. Furthermore, the baffle plate also acts as a lateral restraint for suspended solids (such as food scraps and debris) trapped on the filter mesh surface, preventing them from sliding laterally off the belt conveyor with the water flow. The suspended solids can be discharged through the slag outlet from the baffle plate and transported to the discharge end.

[0073] In this embodiment, the filter mesh transition section of the belt filter has a vertical section extending downward in the vertical direction in the middle region.

[0074] like Figure 1 As shown, the wastewater treatment system also includes a filter cake collection box 300, such as... Figure 4 As shown, the filter cake collection box includes:

[0075] Box 310, the entire box is located below the discharge end of the belt filter;

[0076] The slag scraper 320 is inclinedly installed inside the box, and one side of the slag scraper is in contact with the side of the vertical section near the discharge end of the belt filter.

[0077] The filter cake collection box is fixed to the outside of the housing. The filter cake travels with the filter belt to the discharge end and falls into the collection box under gravity, preventing it from falling onto the wastewater treatment pond or the ground, thus reducing subsequent cleaning and maintenance workload. When the filter belt carries residual filter cake through the transition section, the scraper physically removes the filter cake adhering to the surface of the belt, reducing residual filter cake on the filter cloth and improving the belt filter's continuous retention effect on suspended solids in wastewater. The collected filter cake is temporarily stored in the box, eliminating the need for frequent on-site cleaning of the belt filter's discharge end. Staff can periodically remove and dispose of the filter cake in the box (e.g., for resource utilization or compliant disposal).

[0078] like Figure 7 As shown, the wastewater treatment system also includes:

[0079] Data acquisition module 600 is used to acquire the oil layer thickness, water inflow rate and filter residue thickness in the oil-water separation zone.

[0080] The control module 500 is used to acquire the inlet water flow rate and filter cake thickness, calculate the travel speed of the filter belt in the belt filter based on the inlet water flow rate and filter cake thickness, adjust the travel speed of the filter belt based on the calculation result, acquire the oil layer thickness in the oil-water separation zone, determine oil discharge based on the oil layer thickness in the oil-water separation zone, and activate the scraper module and / or the oil discharge port based on the oil discharge determination result.

[0081] Specifically, the method for activating the scraper module and / or the oil drain port based on the oil drain judgment result is as follows:

[0082] When the oil layer thickness in the oil-water separation zone is greater than or equal to the first threshold, the valve controlling the oil drain port is fully opened, and the second power unit is controlled or kept stopped.

[0083] When the oil layer thickness in the oil-water separation zone is less than the first threshold and greater than the second threshold, the rotation speed of the second turntable and the valve opening of the oil outlet are calculated based on the oil layer thickness. The output of the second power unit is controlled based on the calculation result of the rotation speed of the second turntable, and the valve of the oil outlet is controlled to open at the preset opening based on the calculation result of the valve opening of the oil outlet.

[0084] When the oil layer thickness in the oil-water separation zone is less than or equal to the second threshold, the control oil drain port is completely closed, and the second power unit is started to run at a preset speed;

[0085] Wherein, the first threshold is greater than the second threshold.

[0086] In this embodiment, the specific method for calculating the traveling speed of the filter belt in the belt filter based on the influent flow rate and the filter cake thickness is as follows:

[0087] ;

[0088] in, v t for t The speed of the filter belt at all times, in meters per second; k p This is the proportional adjustment coefficient, measured in seconds. D t The thickness of the filter residue on the filter belt at time t, in meters; D 0 represents the target filter cake thickness, in meters; k f This is the feedforward adjustment coefficient; Q t for t The inflow rate at any given time, expressed in cubic meters per second; Q 0 represents the rated flow rate, measured in cubic meters per second. v t-1 for t -1 is the speed of the filter belt at time 1, in meters per second; t -1 is the time when t The moment before the moment.

[0089] The filter belt is obtained by calculation using the above method. t After determining the travel speed at a given time, the control module adjusts the speed based on the filter belt. t The travel speed at any given moment is converted into a corresponding physical control signal. If the drive device is an analog speed-regulating motor, then an output signal is generated that corresponds to the speed of travel at any given moment. v t The speed is set to a proportional analog voltage or current signal (e.g., 0-10V DC or 4-20mA). If the drive unit is a frequency converter or servo drive, the speed setpoint is sent to the drive via a digital communication protocol (e.g., Modbus, PROFINET) or pulse frequency modulation. Upon receiving the control signal from the control module, the filter module's drive unit (e.g., motor, frequency converter) immediately adjusts its output power and speed to drive the filter belt to approach the setpoint. v t The belt operates at the target speed. Feedback on the actual speed of the conveyor belt (which can be measured via an encoder) is sent back to the control module, compared with the set value, and adjusted by the PID control within the drive or by secondary calibration of the control module.

[0090] In this embodiment, the specific method for calculating the rotational speed of the second turntable and the valve opening of the oil outlet based on the oil layer thickness is as follows:

[0091] ;

[0092] in, V t for t The target opening degree of the oil drain valve at all times; H t for t Real-time oil layer thickness measured in the oil-water separation zone, in millimeters; H 1 represents the second threshold, measured in millimeters. H 2 represents the first threshold, measured in millimeters.

[0093] The formula calculates the valve opening proportionally based on the relative position of the current oil thickness within the high and low threshold ranges. The thicker the oil layer, the larger the opening to enhance gravity-driven oil drainage; the thinner the oil layer, the smaller the opening to reduce the risk of water and oil co-drainage. When the oil layer thickness exceeds the first threshold, the opening reaches 100%; when the oil layer thickness is less than the second threshold, the valve at the drain port is completely closed.

[0094] ;

[0095] in, ω 1t for t The target rotational speed of the second turntable at any given time, in revolutions per minute; ω 1max This is the maximum operating speed of the second turntable, measured in revolutions per minute.

[0096] This embodiment is obtained through calculation using the above formula. t The control module adjusts the valve opening at the oil drain port and the target rotation speed of the second turntable based on these parameters. t The control module generates a linear adjustment control signal based on the valve opening at the oil drain port and sends it to the electric valve at the oil drain port (such as a stepper motor driven valve). For example, if the target opening is 30%, the signal will instruct the valve's stepper motor to rotate a preset angle, causing the valve core to open from the current opening to 30%. t At any given time, the target rotation speed of the second turntable is determined, and a pulse width modulation (PWM) control signal is generated. For example, if the target rotation speed is 15 r / min, the signal will adjust the input pulse frequency of the servo motor, causing the motor to drive the second turntable to increase or decrease its rotation speed from the current speed to 15 r / min.

[0097] In addition, the control module can also calculate the rotational speed of the first turntable based on the oil layer thickness in the oil-water separation zone, as follows:

[0098] ;

[0099] in, ω 2t for t The target rotation speed of the first turntable at any given time, in revolutions per minute; ω 20 This is the base rotational speed of the second turntable, measured in revolutions per minute. γ This is the speed adjustment gain coefficient, measured in revolutions per minute per millimeter.

[0100] This embodiment is obtained through calculation using the above formula. t The target rotation speed of the first turntable is determined by the control module based on the time. t At any given moment, the target rotation speed of the first turntable generates a pulse width modulation (PWM) control signal.

[0101] The control module in this embodiment calculates based on real-time monitoring data of influent flow rate and filter cake thickness. t The filter belt speed can be adjusted according to actual working conditions, enabling adaptive adjustment of the filter belt under different filter cake conditions. When the filter cake thickness is greater than the target thickness or the influent flow rate is greater than the rated flow rate, the filter belt speed is increased to quickly transport the filter cake to the discharge end, preventing excessive filter cake accumulation and clogging of the mesh, thus improving the wastewater filtration effect. When the filter cake thickness is less than the target thickness or the influent flow rate is less than the rated flow rate, the filter belt speed is reduced, which can reduce the energy consumption of the drive motor without affecting the filtration efficiency.

[0102] The control module, based on real-time data of the oil layer thickness in the oil-water separation zone, performs phased adjustments to the opening of the oil drain port and the rotation speed of the second rotary table. This improves upon the problems of floating oil accumulation and water carryover during traditional manual adjustments, for example, in cases of high oil layer thickness ( t When the real-time oil layer thickness measured in the oil-water separation zone is greater than the first threshold, the oil drain port is controlled to be 100% fully open, and the second rotary table is stopped (oil scraping is paused) to quickly discharge a large amount of floating oil; the middle oil layer thickness ( t When the real-time oil layer thickness measured in the oil-water separation zone is less than the first threshold and greater than the second threshold, the thicker the oil layer, the larger the valve opening at the oil drain port, and the smaller the rotation speed of the second rotary table; the lower the oil layer thickness ( tWhen the real-time oil layer thickness measured in the oil-water separation zone is less than the second threshold, the oil drain port is completely closed (to prevent water from being carried over during oil discharge), and the second turntable starts at a preset speed. Based on the oil layer thickness, the control module calculates the target rotation speed of the first turntable (corresponding to the overflow zone), achieving a match between the oil scraping efficiency in the overflow zone and the oil layer condition. For example, when the oil layer thickness in the oil-water separation zone increases (indicating that there may be more residual floating oil in the subsequent overflow zone), the scraping rate of the residual floating oil in the overflow zone is accelerated. This embodiment can automatically adapt to the operating conditions of fluctuating influent flow rate, changes in suspended solids concentration, and dynamic changes in oil layer thickness in food processing plants, achieving intelligent control of the filter belt, oil discharge, and oil scraping, reducing the load on the subsequent biological treatment unit.

[0103] In this embodiment, the data acquisition module includes:

[0104] The oil layer thickness sensing unit is used to monitor the thickness of the floating oil layer on the surface of the oil-water separation zone and overflow zone in real time. This oil layer thickness sensing unit can employ a non-contact ultrasonic sensor or a laser rangefinder sensor. The sensor is installed directly above the liquid surface in the area to be measured, emitting a probe wave vertically downwards and receiving the echo. By analyzing the time difference between the transmitted and received signals, and based on a preset model of the difference in sound or light wave propagation characteristics between wastewater and grease, the distances between the sensor and the oil layer surface, the oil-water interface, and ultimately the bottom of the water layer are calculated, thus obtaining the real-time oil layer thickness. This sensing unit transmits continuous analog or digital thickness signals to the control module.

[0105] The inlet flow rate sensing unit is used to accurately measure the instantaneous flow rate of sewage entering the system. It can be an electromagnetic flow meter or an ultrasonic flow meter, installed on the inlet pipe. Electromagnetic flow meters, based on Faraday's law of electromagnetic induction, measure the induced electromotive force generated by the flow of a conductive liquid (sewage) in a magnetic field to calculate the flow rate. Ultrasonic flow meters, on the other hand, measure the flow velocity using the time-of-flight method or the Doppler effect. This inlet flow rate sensing unit can output a standard analog current signal or digital pulse signal proportional to the instantaneous flow rate, which is fed back to the control module in real time.

[0106] The filter cake thickness sensing unit is used for online monitoring of the thickness of the filter cake layer accumulated on the surface of the belt filter. It can employ a laser displacement sensor or an ultrasonic distance sensor, fixedly installed above the filter mesh support section, to scan and measure the area of ​​filter cake accumulation on the belt surface. The sensor measures the distance from itself to the outermost surface of the filter cake, and by comparing this distance with a reference distance measured at that location when there is no filter cake (or when the belt is clean), the filter cake thickness can be obtained in real time. The measurement data is uploaded to the control module in analog or digital communication format.

[0107] All the above sensing units are connected to the control module via fieldbus (such as RS-485, CAN bus) or industrial Ethernet (such as Profinet, Ethernet / IP). The control module polls or receives all sensor data in real time according to a preset sampling period (such as per second).

[0108] In addition, the data acquisition module may also include:

[0109] Temperature sensors can be installed near the heater or below the liquid surface in the oil-water separation zone and overflow zone to monitor the actual temperature of wastewater, provide feedback signals for the PID control of the heater, and achieve stable temperature control.

[0110] Level switches or sensors are installed in each processing area to monitor extreme high or low liquid levels.

[0111] Example 2:

[0112] This embodiment provides a wastewater treatment method, which is executed using a wastewater treatment system described in Embodiment 1. The wastewater treatment method includes:

[0113] S100: Start the equipment. The filter belt of the belt filter moves continuously at the initial speed. Wastewater is injected through the inlet pipe and filtered by the filter belt. Solid waste is trapped and forms filter cake, which remains on the surface of the filter belt. As the filter belt moves to the outlet, it falls into the filter cake collection box under the action of gravity. The filter cake attached to the filter belt is scraped off by the scraper in the transition section and falls into the filter cake collection box. The filtrate flows through the belt into the wastewater collection tank below, and then enters the oil-water separation zone of the sewage treatment tank through the drain outlet. The control module obtains the inlet flow rate and filter cake thickness in real time, calculates the moving speed of the filter belt in the belt filter based on the inlet flow rate and filter cake thickness, and adjusts the moving speed of the filter belt based on the calculation result.

[0114] Specifically, after the wastewater treatment system is started, the control module is powered on, and the various sensors (flow sensor, filter cake thickness sensor, and oil layer thickness sensor) begin to operate. Driven by the drive unit, the belt filter begins to move continuously at a preset initial safe speed. Oily and solid wastewater discharged from the food processing plant is injected into the system through the inlet pipe. The wastewater is first distributed on the filter cloth support section of the belt filter. Suspended solids in the wastewater (such as food scraps and debris) are trapped by the filter cloth, forming a filter cake layer that remains on the surface of the cloth. The filtrate, after solid removal, passes through the mesh under gravity and drips into the wastewater collection tank below for temporary storage, then flows into the oil-water separation zone of the wastewater treatment tank through the drain outlet. The filter belt with the filter cake continues to move to the discharge end. In the vertical section of the transition zone, a fixed scraper plate contacts the surface of the belt, scraping off the remaining filter cake. The scraped-off filter cake and the filter cake that falls due to gravity at the discharge end both fall into the filter cake collection box below, completing the centralized collection of solid waste. The control module acquires the influent flow rate and filter cake thickness in real time, and calculates based on a feedforward-feedback composite control algorithm. t The speed of the filter belt at all times is calculated using the method described in Example 1. t The system calculates the speed of the filter belt in real time. When the measured filter cake thickness exceeds the target value, the filter belt speed is increased to prevent clogging; conversely, the speed is decreased to ensure filtration efficiency. When the flow rate increases, the filter belt speed is increased to handle the increased impurity load; when the flow rate decreases, the filter belt speed is reduced to save energy. The control module converts the calculated speed command into control signals (such as analog voltage or communication commands) and sends them to the filter module's drive unit (such as a frequency converter) to achieve real-time adjustment of the belt speed.

[0115] S200: Wastewater entering the oil-water separation zone gradually rises to form an oil layer under the assistance of settling and heater. When the waste liquid rises to the preset height, the control module obtains the oil layer thickness in the oil-water separation zone in real time, makes an oil discharge judgment based on the oil layer thickness in the oil-water separation zone, and opens the scraper module and / or the oil discharge port based on the oil discharge judgment result.

[0116] Specifically, the filtrate entering the oil-water separation zone is allowed to settle. Simultaneously, the heater in this zone activates according to control commands, maintaining the wastewater temperature within a suitable range (e.g., 35-45℃) to ensure the animal and vegetable oils remain liquid. Once the liquid level rises to the working height, the control module uses an oil layer thickness sensor to obtain the oil layer thickness in the oil-water separation zone in real time. Based on a comparison with a preset threshold, it enters one of the following operating modes:

[0117] 1. At high oil layer thickness ( tWhen the real-time oil layer thickness measured in the oil-water separation zone is greater than the first threshold, the oil drain port is controlled to be 100% fully open, and the second rotary table is stopped (oil scraping is paused) to quickly discharge a large amount of floating oil.

[0118] 2. Thickness of the intermediate oil layer ( t When the real-time oil layer thickness measured in the oil-water separation zone is less than the first threshold and greater than the second threshold, the control module... t The oil layer thickness in the oil-water separation zone is calculated based on the valve opening at the oil drain port and the rotation speed of the second turntable. The specific calculation method is the same as that described in Example 1 for calculating the rotation speed of the second turntable and the valve opening at the oil drain port. The control module generates corresponding analog or PWM signals based on the calculation results to control the valve opening and the rotation speed of the second power unit, respectively.

[0119] 3. Low oil layer thickness ( t When the real-time oil layer thickness measured in the oil-water separation zone is less than the second threshold, it is determined that the floating oil layer is very thin. In order to avoid water and oil being discharged together, the oil drain port is completely closed. The control module outputs a command to completely close the oil drain port valve and start the second power unit to run at a preset low speed, driving the second turntable to rotate continuously, adhering to and removing the thin oil layer remaining on the water surface.

[0120] As the second turntable rotates and carries the grease-coated surface past the fixed scraper, the grease is scraped off. The scraped grease collects along the oil guide grooves on the scraper surface and flows under gravity into the inclined drain trough below, eventually being discharged to the waste oil collection device.

[0121] S300: Wastewater in the lower layer of the oil-water separation zone enters the adjacent overflow zone through the overflow channel and remains there. The residual trace amount of floating oil floats to the top. When the waste liquid rises to the preset height, the first power device drives the first turntable to rotate continuously. The floating oil on the liquid surface is adhered to the surface of the first turntable. As the first turntable continues to rotate, the grease-adhered turntable surface passes through a fixed inclined scraper. The edge of the scraper keeps in contact with the surface of the first turntable, continuously scraping off the grease layer adhering to the surface of the first turntable. The scraped grease is collected along the oil guide groove and guided to its lowest end by gravity, and finally drips into the oil discharge groove set below. Wastewater flows through the same overflow plate channel structure and passes through the subsequent overflow zones in sequence, repeating the above oil removal process.

[0122] Specifically, the lower oil-containing wastewater in the lower layer of the oil-water separation zone, under the influence of the liquid level difference, enters the adjacent first-stage overflow zone from bottom to top through the overflow channel formed by two sets of staggered overflow plates. This process utilizes the principle of communicating vessels and the physical obstruction of surface floating oil by the overflow plates to achieve efficient oil-water separation and water flow transfer. The wastewater is allowed to settle again in the overflow zone, and the remaining fine oil droplets further float to the liquid surface with the assistance of a heater. The first power unit drives the first turntable to rotate at a preset speed. The control module calculates the rotation speed of the first turntable based on the oil layer thickness in the oil-water separation zone. The specific calculation method can be found in the calculation method of the rotation speed of the first turntable described in Example 1. t A pulse width modulation (PWM) control signal is generated based on the target rotation speed of the first turntable and sent to the first power unit to regulate its output speed. As the first turntable rotates, floating oil from the overflow zone adheres to its surface. When the oil-coated turntable surface passes a fixed scraper, the oil is scraped off and guided into the oil discharge tank for collection via the oil guide channel. Wastewater flows sequentially through subsequent overflow zones using the same overflow structure. This process is repeated at each stage, achieving a gradual decrease in oil content.

[0123] The lower layer of sewage from the overflow zone of the adjacent drainage zone enters the drainage zone through the bottom connection, while the upper layer of sewage in the drainage zone is discharged from the system through the drainage pipe.

[0124] Specifically, the lower layer of clean water, after being deeply purified in the final overflow zone, enters the drainage zone through the bottom connection between this zone and the drainage zone and is left to stand. The upper layer of clean water that meets the discharge standards is discharged from the system through the drainage pipe and enters the subsequent treatment unit or is discharged in compliance with the standards.

[0125] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A sewage treatment system characterised in that, The sewage treatment system comprises a sewage treatment tank, a water inlet pipeline and a water outlet pipeline, the water inlet pipeline and the water outlet pipeline are arranged on opposite sides of the sewage treatment tank and communicate with the inside of the sewage treatment tank, the sewage treatment tank comprises, from the side provided with the water inlet pipeline to the side provided with the water outlet pipeline, an oil-water separation zone, overflow zones and a water discharge zone, the overflow zones are arranged in plurality, two groups of overflow plates are arranged between the oil-water separation zone and the adjacent overflow zones and between the adjacent overflow zones, the two groups of overflow plates vertically extend along the height direction of the sewage treatment tank and are fixed to the inner walls of the tank bodies on opposite sides of the sewage treatment tank, the two groups of overflow plates are arranged in up-down staggered mode to form overflow channels, the lower sewage in the oil-water separation zone or the overflow zones enters the overflow channels from the bottom and overflows to the adjacent overflow zones from the top, the water discharge zone and the adjacent overflow zone thereof are separated by one group of overflow plates, the bottom of the overflow plate arranged between the water discharge zone and the adjacent overflow zone thereof and the bottom of the sewage treatment tank form a communication port, and an oil discharge port is arranged at the upper part of the oil-water separation zone; The sewage treatment system further comprises a scraper module, and the scraper module is fixed to the upper part of the sewage treatment tank as a whole. The scraper module comprises: a first rotating disc arranged at the upper part of the overflow zone and driven to rotate by a first power device; a second rotating disc arranged at the upper part of the oil-water separation zone and driven to rotate by a second power device; a scraper arranged in a whole body in an inclined mode, wherein the upper surface of the scraper is recessed inward to form an oil guide groove arranged along the extension direction of the scraper, and one side of the scraper is in contact with the surface of the first rotating disc or the second rotating disc; an oil discharge groove arranged in a whole body in an inclined mode, and the maximum height side of the oil discharge groove is arranged below the lowest height end of the scraper; The sewage treatment system further comprises a filter module, and the filter module is arranged below the water outlet end of the water inlet pipeline as a whole. The filter module comprises: a belt filter; a wastewater collection tank arranged between the filter screen cloth bearing section and the transition section of the belt filter, and provided with a water discharge port communicating with the oil-water separation zone at the lower part of one side of the wastewater collection tank; The sewage treatment system further comprises: a data acquisition module for acquiring the oil layer thickness of the oil-water separation zone, the water inlet flow and the filter residue thickness; a control module for acquiring the water inlet flow and the filter residue thickness, calculating the travel speed of the filter screen belt in the belt filter according to the water inlet flow and the filter residue thickness, adjusting the travel speed of the filter screen belt based on the calculation result of the travel speed of the filter screen belt, acquiring the oil layer thickness of the oil-water separation zone, judging oil discharge according to the oil layer thickness of the oil-water separation zone, and opening the scraper module and / or the oil discharge port according to the oil discharge judgment result; The specific mode of opening the scraper module and / or the oil discharge port according to the oil discharge judgment result is as follows: when the oil layer thickness of the oil-water separation zone is greater than or equal to a first threshold value, the valve of the oil discharge port is completely opened, and the second power device is controlled or kept to stop; When the oil layer thickness of the oil-water separation zone is less than the first threshold value and greater than the second threshold value, the second rotating disc rotating speed and the valve opening degree of the oil discharge port are calculated according to the oil layer thickness, the second power device is controlled to output based on the second rotating disc rotating speed calculation result, and the valve of the oil discharge port is controlled to open at a preset opening degree based on the valve opening degree calculation result of the oil discharge port; When the oil layer thickness of the oil-water separation zone is less than or equal to the second threshold value, the oil discharge port is controlled to be completely closed, and the second power device is started to operate at a preset speed; The first threshold value is greater than the second threshold value. The specific manner of calculating the second rotating disc rotating speed and the valve opening degree of the oil discharge port according to the oil layer thickness is as follows: ； ； wherein, V t is t target opening of the oil outlet valve at the moment; H t is t real-time oil layer thickness measured by the oil-water separation zone at the moment, in millimeters; H 1 is a second threshold value, in millimeters; H 2 is a first threshold value, in millimeters; ω 1t is t target rotating speed of the second rotating disc at the moment, in revolutions per minute; ω 1max is the maximum working rotating speed of the second rotating disc, in revolutions per minute.

2. A sewage treatment system as claimed in claim 1, characterised in that Heaters are arranged in the oil-water separation zone and the overflow zone.

3. The sewage treatment system of claim 1, wherein The filter module further comprises a water baffle, which is enclosed on the surface of the filter screen cloth bearing section, the water outlet end of the water inlet pipeline is arranged in the enclosed area of the water baffle, and the water baffle is provided with a slag outlet close to the discharge end of the belt filter.

4. The sewage treatment system of claim 1, wherein The middle area of the transition section of the filter screen cloth of the belt filter has a vertical section extending downward in the vertical direction. The sewage treatment system further comprises a filter slag collecting box, which comprises: a box body, which is arranged below the discharge end of the belt filter as a whole; a slag scraping plate, which is arranged in the box body as a whole and is inclined, and one side of the slag scraping plate is in contact with the side surface of the vertical section close to the discharge end of the belt filter.

5. A method of sewage treatment, characterised in that, The sewage treatment method is performed by the sewage treatment system of claim 1, and the sewage treatment method comprises: starting the equipment, the filter screen belt of the belt filter continuously travels at an initial speed, wastewater is injected through the water inlet pipeline, and the filter screen belt filters the wastewater, wherein solid waste is intercepted to form filter slag, which is retained on the surface of the filter screen belt and travels to the discharge end with the filter screen belt, and falls into the filter slag collecting box under the action of gravity, the filter slag attached to the filter screen belt is scraped off by the slag scraping plate in the transition section and falls into the filter slag collecting box, and the filtrate passes through the screen belt and flows into the wastewater collecting tank below, and then enters the oil-water separation zone of the sewage treatment tank through the drainage port, the control module obtains the water inlet flow rate and the filter slag thickness in real time, calculates the traveling speed of the filter screen belt of the belt filter according to the water inlet flow rate and the filter slag thickness, and adjusts the traveling speed of the filter screen belt based on the traveling speed calculation result of the filter screen belt; The sewage entering the oil-water separation zone gradually floats to form a floating oil layer under the action of standing and the auxiliary action of the heater, the control module obtains the oil layer thickness of the oil-water separation zone in real time, judges oil discharge according to the oil layer thickness of the oil-water separation zone, and opens the scraper module and / or the oil discharge port according to the oil discharge judgment result. The sewage under the oil-water separation zone enters the adjacent overflow zone through the overflow channel and stands still. The residual trace of floating oil floats up. When the waste liquid rises to a preset height, the first power device drives the first rotating disc to continue rotating. The floating oil on the liquid surface is adhered to the surface of the first rotating disc. With the continuous rotation of the first rotating disc, the surface of the rotating disc with the adhered oil is passed through the fixed inclined scraper. The edge of the scraper is in contact with the surface of the first rotating disc. The oil layer adhered to the surface of the first rotating disc is continuously scraped off. The scraped off oil is collected along the oil guide groove and is guided to the lowest end thereof by gravity. Finally, the oil drops into the oil drain groove arranged below. The sewage passes through the subsequent overflow zones in sequence through the same overflow plate channel structure, and the above oil removal process is repeated. The sewage under the overflow zone of the adjacent drainage zone enters the drainage zone through the bottom communication port. The upper sewage in the drainage zone is discharged from the system through the drainage pipeline.

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