Winter total nitrogen up-to-standard sewage treatment system and method based on CASS (cyclic activated sludge system) process

Abstract

The invention relates to the technical field of sewage treatment, in particular to a system and method for treating sewage with total nitrogen reaching the standard in winter based on a CASS (cyclic activated sludge system) process, and the system comprises a water distribution channel which is used for being communicated with an external sewage pipe; the multiple groups of CASS biochemical reaction tanks are communicated with the water distribution channel, and the communication states of at least two groups of CASS biochemical reaction tanks and the water distribution channel are opposite; the regulating tank is communicated with the water distribution channel, and the regulating tank is communicated with the CASS biochemical reaction tank; according to the present invention, the continuous treatment and the continuous water discharging of the sewage can be achieved through the multiple groups of the CASS biochemical reaction tanks, the nitrification liquid in the CASS biochemical reaction tanks flows back to the adjusting tank, and the anoxic environment in the adjusting tank is maintained; the effects that the total nitrogen of the sewage is reduced to reach the standard and the transformation cost is low can be achieved under the conditions that the temperature is low in winter and a sewage treatment plant cannot add a new site.

Description

Technical Field

[0001] The present application relates to the technical field of sewage treatment, and in particular to a sewage treatment system and method for meeting total nitrogen standards in winter based on a CASS process. Background Art

[0002] Urban wastewater refers to wastewater generated from urban residents' daily life, commercial and industrial production activities. It contains various pollutants, among which the nitrogen-containing pollutants in the influent of urban domestic sewage treatment plants are mainly ammonia nitrogen. Before the wastewater is discharged into the natural environment, it needs to undergo a series of treatments to remove or reduce the pollutant content, thereby protecting the environment and human health.

[0003] At present, sewage treatment systems mainly include sequencing batch activated sludge (SBR) process, CASS process, oxidation ditch, AAO process and other variant processes. Sewage treatment plants built earlier generally adopt CASS process. The CASS process steps are generally to first let sewage from the outside enter the screen trough through underground pipes to remove large floating particles and then flow into the regulating tank. Then the sewage in the regulating tank is lifted to the fine screen trough by the lifting pump, and then flows to the outdoor grit tank for sand and water separation. The sewage after the above treatment enters the CASS biochemical reaction tank for anoxic stirring reaction and aerobic aeration reaction to remove organic matter and nitrogen and phosphorus. Then the treated water enters the sedimentation tank for sedimentation, and finally the treated clean water is discharged through a liftable automatic skimmer.

[0004] Regarding the above-mentioned related technologies, denitrification reaction occurs in the precipitation stage of the CASS process to reduce the total nitrogen concentration, and the temperature has a great influence on the denitrification reaction. In most parts of northern my country, the inlet water temperature of the sewage treatment plant is low in winter. When the water temperature is lower than 8°C, the denitrification effect of the activated sludge is extremely inhibited, making the total nitrogen in the effluent unable to meet the standard. Therefore, it is necessary to add a deep treatment system. However, some sewage treatment plants that were built earlier have not reserved vacant land and cannot provide the space required for deep treatment systems such as biological rotary membrane bioreactors, denitrification deep bed filters, and flocculation sedimentation tanks. Summary of the invention

[0005] In order to achieve total nitrogen compliance in winter sewage treatment under existing site conditions and reduce the required renovation costs, the present application provides a winter total nitrogen compliance sewage treatment system and method based on the CASS process.

[0006] The present application provides a winter total nitrogen standard sewage treatment system and method based on the CASS process, which adopts the following technical solutions: In a first aspect, the present application provides a winter total nitrogen standard treatment system based on the CASS process.

[0007] A winter total nitrogen standard sewage treatment system based on CASS process, comprising: A water distribution channel, the water distribution channel is used to communicate with an external sewage pipe; A plurality of groups of CASS biochemical reaction pools, wherein the plurality of groups of CASS biochemical reaction pools are connected to the water distribution channel, and at least two groups of the CASS biochemical reaction pools are connected in opposite states to the water distribution channel; A regulating tank is connected to the water distribution channel, and the regulating tank is connected to the CASS biochemical reaction tank.

[0008] By adopting the above technical solution, the external sewage pipe is connected with the water distribution channel so that the external sewage enters the water distribution channel; then the sewage in the water distribution channel is introduced into the CASS biochemical reaction pool for aeration, sedimentation and decanting operations in sequence, and the connection state between the water distribution channel and the CASS biochemical reaction pool is controlled so that the connection state between at least two groups of the CASS biochemical reaction pools and the water distribution channel is opposite, so as to achieve continuous water inflow and continuous water outflow of the CASS biochemical reaction pool; then, when aeration is performed in the CASS biochemical reaction pool, the nitrification liquid is pumped into the regulating pool. Since more than 90% of the total nitrogen in the influent of the urban sewage treatment plant exists in the form of ammonia nitrogen, in the CASS During the aeration or aeration stage of the biochemical reaction tank, the activated sludge microorganisms will quickly convert ammonia nitrogen into nitric nitrogen under the condition of sufficient dissolved oxygen (>3mg / L), and then return the nitrified liquid containing nitric nitrogen to the regulating tank and use the anoxic environment formed in the regulating tank to carry out denitrification reaction; the sludge water in the regulating tank is then pumped into the water distribution channel and then enters the CASS biochemical reaction tank for sedimentation and decanting. Since the regulating tank is not aerated, the dissolved oxygen in the regulating tank is less than 0.5mg / L, which is an excellent anoxic environment, which is conducive to the denitrification reaction of denitrifying bacteria and can convert all nitric nitrogen into nitrogen gas. Therefore, the sludge water from the regulating tank to the CASS The nitric nitrogen in the return sludge of the biochemical reaction tank is extremely low or zero; finally, the upper layer of qualified clean water in the CASS biochemical reaction tank after sedimentation is decanted to the outside; the designed winter total nitrogen qualified sewage treatment system based on the CASS process can adjust the sewage sent from the external sewage pipe through the distribution channel according to the current process stage of the CASS biochemical reaction tank to ensure the continuous water inflow treatment of sewage, and can achieve continuous treatment and continuous water discharge of sewage through multiple groups of CASS biochemical reaction tanks. By returning the nitrified liquid in the CASS biochemical reaction tank to the regulating tank and maintaining the anoxic environment in the regulating tank, the total nitrogen in the sewage can be reduced to meet the standard when the temperature is low in winter and the sewage treatment plant cannot add new sites, and the cost of transformation is low.

[0009] In a specific implementation scheme, a reflux pump is provided in the CASS biochemical reaction tank, the water outlet of the reflux pump is connected to a reflux pipe, and one end of the reflux pipe away from the reflux pump extends into the regulating tank to achieve connectivity between the regulating tank and the CASS biochemical reaction tank.

[0010] By adopting the above technical solution, the designed reflux pump and reflux pipe can pump the nitrified liquid produced in the aeration stage of the CASS biochemical reaction tank into the regulating tank for denitrification reaction.

[0011] In a specific possible implementation manner, the regulating tank is used to be connected to an external sewage pipe.

[0012] By adopting the above technical solution, the regulating tank designed to be connected to the external sewage pipe can complete the denitrification reaction of the nitrified liquid as an anoxic tank while also having the capacity to regulate the peaks and troughs of sewage.

[0013] In the second aspect, the present application provides a winter total nitrogen standard sewage treatment method based on the CASS process, comprising: S1: Sewage inflow: connect the external sewage pipe with the water distribution channel so that the external sewage can enter the water distribution channel; S2: Sewage treatment: The sewage in the water distribution channel is introduced into the CASS biochemical reaction pool for aeration, sedimentation and decanting operations in sequence, and the connection state between the water distribution channel and the CASS biochemical reaction pool is controlled so that the connection state between at least two groups of the CASS biochemical reaction pools and the water distribution channel is opposite, so as to achieve continuous water inflow and continuous water outflow of the CASS biochemical reaction pool; S3: Nitrification liquid reflux: When aeration is performed in the CASS biochemical reaction tank, the nitrification liquid is pumped into the regulating tank, and an anoxic environment is formed in the regulating tank to perform denitrification reaction; S4: Sludge return: pump the sludge water in the regulating tank into the water distribution channel, and then enter the CASS biochemical reaction tank for sedimentation and decanting; S5: Clean water discharge: The upper clean water that meets the standards after sedimentation in the CASS biochemical reaction tank is decanted to the outside.

[0014] By adopting the above technical solution, the external sewage pipe is connected with the water distribution channel so that the external sewage enters the water distribution channel; then the sewage in the water distribution channel is introduced into the CASS biochemical reaction pool for aeration, sedimentation and decanting operations in sequence, and the connection state between the water distribution channel and the CASS biochemical reaction pool is controlled so that the connection state between at least two groups of the CASS biochemical reaction pools and the water distribution channel is opposite, so as to achieve continuous water inflow and continuous water outflow of the CASS biochemical reaction pool; then, when aeration is performed in the CASS biochemical reaction pool, the nitrification liquid is pumped into the regulating pool. Since more than 90% of the total nitrogen in the influent of the urban sewage treatment plant exists in the form of ammonia nitrogen, in the CASS During the aeration or aeration stage of the biochemical reaction tank, the activated sludge microorganisms will quickly convert ammonia nitrogen into nitric nitrogen under the condition of sufficient dissolved oxygen (>3mg / L), and then return the nitrified liquid containing nitric nitrogen to the regulating tank and use the anoxic environment formed in the regulating tank to carry out denitrification reaction; the sludge water in the regulating tank is then pumped into the water distribution channel and then enters the CASS biochemical reaction tank for sedimentation and decanting. Since the regulating tank is not aerated, the dissolved oxygen in the regulating tank is less than 0.5mg / L, which is an excellent anoxic environment, which is conducive to the denitrification reaction of denitrifying bacteria and can convert all nitric nitrogen into nitrogen gas. Therefore, the sludge water from the regulating tank to the CASS The nitrate nitrogen in the return sludge of the biochemical reaction tank is extremely low or zero; finally, the upper layer of qualified clean water after sedimentation in the CASS biochemical reaction tank is decanted to the outside; the designed winter total nitrogen qualified sewage treatment method based on the CASS process can adjust the sewage inlet through the distribution channel, which can be sent from the external sewage pipe according to the current process stage of the CASS biochemical reaction tank to ensure the continuous sewage inlet treatment, and can achieve continuous sewage treatment and continuous water discharge through multiple groups of CASS biochemical reaction tanks. By returning the nitrified liquid in the CASS biochemical reaction tank to the regulating tank and maintaining the anoxic environment in the regulating tank, the total nitrogen in the sewage can be reduced to meet the standard when the temperature is low in winter and the sewage treatment plant cannot add new sites, and the cost of transformation is low.

[0015] In a specific possible implementation scheme, in step S1, the sewage in the external sewage pipe enters the distribution channel after passing through the regulating tank.

[0016] By adopting the above technical solution, the denitrification reaction of the nitrified liquid can be completed while the amount and energy of the sewage peaks and troughs can be regulated while serving as an anoxic tank.

[0017] In a specific possible implementation scheme, in step S3, when the denitrification reaction is carried out in the regulating tank, a stirring mechanism is used to stir the sewage mixture in the regulating tank to prevent sludge precipitation in the regulating tank.

[0018] By adopting the above technical solution, by stirring the sewage mixture in the regulating tank, the sedimentation of sludge in the regulating tank can be avoided, thereby improving the effect of the denitrification reaction in the regulating tank.

[0019] In a specific feasible implementation scheme, in step S3, a reflux pump is arranged at the rear end of the CASS biochemical reaction tank, and a reflux pipe is connected to the water outlet of the reflux pump, and one end of the reflux pipe away from the reflux pump extends into the regulating tank, so as to enable the nitrified liquid in the CASS biochemical reaction tank to flow into the regulating tank.

[0020] By adopting the above technical solution, the designed reflux pump and reflux pipe can pump the nitrified liquid produced in the aeration stage of the CASS biochemical reaction tank into the regulating tank for denitrification reaction.

[0021] In a specific embodiment, the stirring mechanism comprises A mounting frame, the mounting frame is set up on the regulating tank; A rotating spindle, the rotating spindle is rotatably connected to the mounting frame, and the rotating axis of the rotating spindle is vertically arranged; A plurality of stirring rods, wherein the stirring rods are connected to the rotating main shaft; A driving assembly is used to drive the rotating main shaft to rotate, wherein the driving assembly is connected to the mounting frame, and the driving assembly is connected to the rotating main shaft.

[0022] By adopting the above technical solution, a stirring mechanism is designed, which can drive the rotating main shaft to rotate through the driving assembly. Multiple stirring rods can be installed simultaneously through the rotating main shaft. The stirring rods can be rotated in the equalization tank to achieve stirring and mixing of the sewage mixture in the equalization tank, thereby reducing the possibility of sludge precipitation in the equalization tank.

[0023] In a specific embodiment, the drive assembly includes A hollow manifold, the manifold is connected to the mounting frame, the manifold is in communication with an external sewage pipe and a return pipe, and the rotating main shaft extends into the manifold and is rotatably connected to the manifold; A plurality of hydraulically driven blades are connected to the rotating main shaft, and the hydraulically driven blades are located in the manifold, with a rotating gap between the hydraulically driven blades and the manifold.

[0024] By adopting the above technical scheme, the sewage in the external sewage pipe and the sewage mixture in the return pipe enters the confluence tube and flows out from the lower end of the confluence tube when flowing through the hydraulically driven blades, and the mixed liquid drives the hydraulically driven blades to rotate when flowing through the hydraulically driven blades, thereby realizing the rotation of the rotating main shaft, and then the rotating main shaft drives the stirring rod to rotate to realize the stirring of the sewage mixture in the regulating tank; the designed driving component can realize the confluence and guidance of the liquid in the external sewage pipe and the return pipe through the confluence tube, and can use the flow of the liquid in the external sewage pipe and the return pipe to drive the rotating main shaft to rotate through the hydraulically driven blades, thereby realizing the stirring of the mixture in the regulating tank.

[0025] In a specific possible implementation scheme, the rotating main shaft and the stirring rod are both hollow, a plurality of water inlet holes are provided on the extension section of the rotating main shaft into the manifold, and the water inlet holes are located below the hydraulically driven blades, and a plurality of water outlet holes are provided on the stirring rod.

[0026] By adopting the above technical scheme, the designed hollow and perforated rotating main shaft and stirring rod can allow the liquid in the external sewage pipe and the return pipe to be introduced through the water inlet hole and discharged from the water outlet hole into the regulating tank, effectively improving the stirring range of the stirring rod, and avoiding the possibility of liquid falling from a high place into the regulating tank and causing splashing, thereby increasing the oxygen content in the regulating tank.

[0027] In summary, the present application includes at least one of the following beneficial technical effects: 1. The designed winter total nitrogen standard sewage treatment system based on CASS process can adjust the sewage sent from the external sewage pipe through the distribution channel according to the current process stage of the CASS biochemical reaction tank to ensure the continuous sewage inlet treatment. Through multiple groups of CASS biochemical reaction tanks, continuous sewage treatment and continuous water discharge can be achieved. By returning the nitrification liquid in the CASS biochemical reaction tank to the regulating tank and maintaining the anoxic environment in the regulating tank, the total nitrogen in the sewage can be reduced to meet the standard when the temperature is low in winter and the sewage treatment plant cannot add new sites, and the cost of transformation is low.

[0028] 2. The designed winter total nitrogen standard sewage treatment system based on the CASS process can pump the nitrified liquid produced in the aeration stage of the CASS biochemical reaction tank into the regulating tank for denitrification reaction through the reflux pump and reflux pipe.

[0029] 3. The designed winter total nitrogen standard sewage treatment system based on CASS process can complete the denitrification reaction of nitrification liquid while regulating the capacity of sewage peaks and troughs through the regulating tank connected to the external sewage pipe as an anoxic tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of a winter total nitrogen standard sewage treatment system based on the CASS process in an embodiment of the present application.

[0031] Figure 2 is Figure 1 Schematic diagram of the structure after the regulating tank is connected to the external sewage pipe.

[0032] Figure 3 It is a schematic diagram of the structure of the regulating tank and the stirring mechanism in the embodiment of the present application.

[0033] Figure 4 yes Figure 3 Sectional view in .

[0034] Explanation of the reference numerals: 01, external sewage pipe; 1, water distribution channel; 2, CASS biochemical reaction tank; 3, regulating tank; 4, reflux pump; 5, reflux pipe; 6, stirring mechanism; 61, mounting frame; 62, rotating main shaft; 621, water inlet; 63, stirring rod; 631, water outlet; 64, driving assembly; 641, confluence tube; 642, hydraulic drive blade. DETAILED DESCRIPTION

[0035] The following is combined with Figure 1-4 This application is described in further detail.

[0036] The embodiments of the present application disclose a winter total nitrogen standard sewage treatment system and method based on the CASS process.

[0037] In a first aspect, an embodiment of the present application discloses a winter total nitrogen standard sewage treatment system based on the CASS process.

[0038] Reference Figure 1 A winter total nitrogen standard sewage treatment system based on the CASS process includes a water distribution channel 1 and a CASS biochemical reaction pool 2. The water distribution channel 1 is connected to an external sewage pipe 01. The number of CASS biochemical reaction pools 2 is multiple groups. Multiple connecting ports are arranged on one side of the water distribution channel 1. Multiple groups of CASS biochemical reaction pools 2 are connected in parallel with the water distribution channel 1 through the connecting ports. By changing the opening and closing states of the connecting ports, the connecting state between the water distribution channel 1 and the CASS biochemical reaction pool 2 is changed, thereby coordinating different process stages of the CASS biochemical reaction pool 2 such as water inlet aeration, sedimentation and decanting. The number of CASS biochemical reaction pools 2 in the present application is two groups.

[0039] Reference Figure 1Furthermore, in winter, due to the low temperature of sewage in the external sewage pipe 01, the denitrification reaction speed in the CASS biochemical reaction tank 2 is slow, and the total nitrogen in the effluent does not meet the standard. At the same time, for some sewage treatment plants that have not reserved a site, it is impossible to reduce the total nitrogen in the effluent by adding a new back-end deep treatment process, nor can it reduce the total nitrogen in the effluent by extending the residence time of the sewage in the CASS biochemical reaction tank 2. At this time, in order to reduce the total nitrogen in the effluent under the above circumstances and to minimize the transformation cost, the winter total nitrogen standard sewage treatment system based on the CASS process also includes a regulating tank 3, which is connected to the water distribution channel 1, and the regulating tank 3 is connected to the CASS biochemical reaction tank 2. By pumping the nitrification liquid in the CASS biochemical reaction tank 2 into the regulating tank 3 for denitrification under anoxic conditions, the sewage mixture is returned to the CASS biochemical reaction tank 2 after the total nitrogen content is reduced, thereby solving the conflict between the anoxic denitrification reaction time period in the CASS biochemical reaction tank 2 and the sewage treatment efficiency, and avoiding the huge engineering workload of adding an in-depth treatment process.

[0040] Reference Figure 1 and Figure 2 Furthermore, a reflux pump 4 is provided in the CASS biochemical reaction tank 2, and a reflux pipe 5 is connected to the water outlet flange of the reflux pump 4. One end of the reflux pipe 5 away from the reflux pump 4 extends into the regulating tank 3. The nitrification liquid in the CASS biochemical reaction tank 2 is pumped into the regulating tank 3 through the cooperation of the reflux pump 4 and the reflux pipe 5.

[0041] Reference Figure 2 Furthermore, the regulating tank 3 is connected to the external sewage pipe 01. The sewage in the external sewage pipe 01 discharges part of the sewage into the regulating tank 3 when the sewage wave peaks, so that the regulating tank 3 also has the function of regulating the rate at which the sewage enters the distribution channel 1.

[0042] The implementation principle of a winter total nitrogen standard sewage treatment system based on the CASS process in the embodiment of the present application is as follows: connect the external sewage pipe 01 with the water distribution channel 1 so that the external sewage enters the water distribution channel 1; then introduce the sewage in the water distribution channel 1 into the CASS biochemical reaction pool 2 for aeration, sedimentation and decanting operations in sequence, and control the connection state between the water distribution channel 1 and the CASS biochemical reaction pool 2 so that at least two groups of CASS biochemical reaction pools 2 have opposite connection states to the water distribution channel 1, so as to achieve continuous water inflow and continuous water outflow of the CASS biochemical reaction pool 2; then, when aeration is performed in the CASS biochemical reaction pool 2, pump the nitrification liquid into the regulating pool 3. Since the total nitrogen in the influent of the urban sewage treatment plant exceeds 9 0% of the nitrogen element exists in the form of ammonia nitrogen. During the aeration or aeration stage of the CASS biochemical reaction tank, the activated sludge microorganisms will quickly convert ammonia nitrogen into nitric nitrogen under the condition of sufficient dissolved oxygen (>3mg / L), and then return the nitrified liquid containing nitric nitrogen to the regulating tank 3 to form an anoxic environment in the regulating tank 3 for denitrification reaction; then the sludge water in the regulating tank 3 is pumped into the water distribution channel 1, and then enters the CASS biochemical reaction tank 2 for sedimentation and decanting. Since the regulating tank 3 is not aerated, the dissolved oxygen in the regulating tank 3 is less than 0.5mg / L, which is an excellent anoxic environment, which is conducive to the denitrification reaction of denitrifying bacteria and can convert all nitric nitrogen into nitrogen gas. Therefore, the sludge water from the regulating tank 3 to the CASS The nitric nitrogen in the return sludge of the biochemical reaction tank is extremely low or zero; finally, the upper layer of clean water that meets the standards after sedimentation in the CASS biochemical reaction tank 2 is decanted to the outside; the sewage sent from the external sewage pipe 01 can be adjusted through the water distribution channel 1 according to the current process stage of the CASS biochemical reaction tank 2 to ensure the continuous water inlet treatment of the sewage, and the continuous treatment and continuous water discharge of the sewage can be achieved through multiple groups of CASS biochemical reaction tanks 2. By returning the nitrified liquid in the CASS biochemical reaction tank 2 to the regulating tank 3 and maintaining the anoxic environment in the regulating tank 3, the total nitrogen in the sewage can be reduced to meet the standards when the temperature is low in winter and the sewage treatment plant cannot add new sites, and the cost of the transformation is low.

[0043] In the second aspect, an embodiment of the present application discloses a method for treating wastewater that meets total nitrogen standards in winter based on the CASS process.

[0044] Reference Figure 1 to Figure 2 A winter total nitrogen standard sewage treatment method based on CASS process, comprising: S1: Sewage inflow: connect the external sewage pipe 01 with the water distribution channel 1 so that the external sewage enters the water distribution channel 1; S2: sewage treatment: the sewage in the water distribution channel 1 is introduced into the CASS biochemical reaction pool 2 for aeration, sedimentation and decanting operations in sequence, and the connection state between the water distribution channel 1 and the CASS biochemical reaction pool 2 is controlled so that the connection state of at least two groups of CASS biochemical reaction pools 2 is opposite to that of the water distribution channel 1, so as to achieve continuous water inflow and continuous water outflow of the CASS biochemical reaction pool 2; specifically, when the sewage enters the first group of CASS biochemical reaction pools 2 through the water distribution channel 1 for aeration, the reflux pump 4 in the first group of CASS biochemical reaction pools 2 is turned on, and the second group of CASS biochemical reaction pools 2 is sedimented at this time, and the reflux pump 4 in the second group of CASS biochemical reaction pools 2 is in a closed state. When the connection relationship between the water distribution channel 1 and the CASS biochemical reaction pool 2 is switched, the aforementioned relationship is reversed; S3: Reflux of nitrified liquid: When aeration is performed in the CASS biochemical reaction tank 2, the nitrified liquid is pumped into the regulating tank 3, and denitrification reaction is performed by means of the anoxic environment formed in the regulating tank 3; S4: Sludge return: The sludge water in the regulating tank 3 is pumped into the water distribution channel 1, and then enters the CASS biochemical reaction tank 2 for sedimentation and decanting; S5: Clean water discharge: The upper clean water that meets the standards after sedimentation in the CASS biochemical reaction tank 2 is decanted to the outside.

[0045] Reference Figure 2 Furthermore, in step S1, the sewage in the external sewage pipe 01 enters the water distribution channel 1 after passing through the regulating tank 3, which can complete the denitrification reaction of the nitrification liquid as an anoxic tank while also regulating the peak and trough of the sewage.

[0046] Reference Figure 2 Furthermore, in step S3, a reflux pump 4 is arranged at the rear end of the CASS biochemical reaction pool 2, and a reflux pipe 5 is connected to the water outlet of the reflux pump 4, and one end of the reflux pipe 5 away from the reflux pump 4 extends into the regulating pool 3, so as to realize that the nitrification liquid in the CASS biochemical reaction pool 2 flows into the regulating pool 3; specifically, the external reflux pipes 5 in the two groups of CASS biochemical reaction pools 2 can be connected in parallel or not. In the embodiment of the present application, the two reflux pipes 5 are not connected in parallel to form two independent sets of nitrification liquid reflux systems, and reduce the installation of butterfly valves on the branch pipes and avoid water accumulation and freezing in the reflux pipes 5 when the reflux pump 4 stops running.

[0047] Reference Figure 3 Furthermore, in step S3, when the denitrification reaction is carried out in the regulating tank 3, the sewage mixture in the regulating tank 3 is stirred by the stirring mechanism 6 to prevent the sludge in the regulating tank 3 from settling; by stirring the sewage mixture in the regulating tank 3, the sedimentation of the sludge in the regulating tank 3 can be avoided, thereby improving the effect of the denitrification reaction in the regulating tank 3.

[0048] Reference Figure 3 and Figure 4 Specifically, the stirring mechanism 6 includes a mounting frame 61, a rotating main shaft 62 and a plurality of stirring rods 63. The mounting frame 61 is erected on the regulating tank 3. The rotating main shaft 62 is rotatably connected to the mounting frame 61 through a thrust ball bearing, and the rotating axis of the rotating main shaft 62 is vertically arranged. The stirring rods 63 are welded and fixed to the rotating main shaft 62, and the plurality of stirring rods 63 are evenly distributed around the circumference of the rotating main shaft 62.

[0049] Reference Figure 3 and Figure 4 Furthermore, in order to drive the rotating main shaft 62 to rotate, and then realize the rotation of the stirring rod 63 in the regulating tank 3 to complete the stirring function, the stirring mechanism 6 also includes a driving component 64, and the driving component 64 is connected to the mounting frame 61, and the driving component 64 is connected to the rotating main shaft 62. Specifically, the driving component 64 includes a manifold 641 and a plurality of hydraulic drive blades 642. The manifold 641 is hollow, and the manifold 641 is welded and fixed to the mounting frame 61. The upper end of the manifold 641 is connected to the external sewage pipe 01 through a flange, and the upper end of the manifold 641 is connected to the return pipe 5 through a flange. The sewage in the external sewage pipe 01 and the return pipe 5 enters the regulating tank 3 after passing through the manifold 641.

[0050] Reference Figure 3 and Figure 4 The rotating main shaft 62 extends into the confluence tube 641, and the rotating main shaft 62 is coaxially arranged with the confluence tube 641. The hydraulically driven blades 642 are welded and fixed to the rotating main shaft 62. The sewage in the external sewage pipe 01 and the sewage mixture in the return pipe 5 enter the confluence tube 641 and flow out from the lower end of the confluence tube 641 when flowing through the hydraulically driven blades 642. When the mixed liquid flows through the hydraulically driven blades 642, the hydraulically driven blades 642 are driven to rotate, thereby realizing the rotation of the rotating main shaft 62. Then, the rotating main shaft 62 drives the stirring rod 63 to rotate, thereby realizing the stirring of the sewage mixture in the regulating tank 3.

[0051] Reference Figure 3 and Figure 4Furthermore, in order to expand the range of action of the stirring rod 63 and reduce the incorporation of oxygen when water enters the regulating tank 3, the rotating main shaft 62 and the stirring rod 63 are both hollow, and the inner cavity of the rotating main shaft 62 is connected to the inner cavity of the stirring rod 63. The lower end of the manifold 641 is rotatably connected to the rotating main shaft 62 through a sealed bearing, and a plurality of water inlet holes 621 are provided on the extending section of the rotating main shaft 62 extending into the manifold 641. The water inlet holes 621 are located below the hydraulically driven blades 642, and a plurality of water outlet holes 631 are provided on the stirring rod 63. The liquid in the external sewage pipe 01 and the return pipe 5 is introduced into the regulating tank 3 through the water inlet holes 621 and discharged from the water outlet holes 631 into the regulating tank 3, thereby effectively improving the stirring range of the stirring rod 63 and avoiding the possibility of liquid falling from a high place into the regulating tank 3, causing splashing, thereby increasing the oxygen content in the regulating tank 3.

[0052] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A winter total nitrogen standard sewage treatment system based on CASS process, characterized by: include: A water distribution channel (1), the water distribution channel (1) being used to communicate with an external sewage pipe (01); A plurality of groups of CASS biochemical reaction pools (2), wherein the plurality of groups of CASS biochemical reaction pools (2) are all connected to the water distribution channel (1), and the connection states of at least two groups of CASS biochemical reaction pools (2) and the water distribution channel (1) are opposite; A regulating tank (3), the regulating tank (3) is connected to the water distribution channel (1), and the regulating tank (3) is connected to the CASS biochemical reaction tank (2).

2. The winter total nitrogen standard sewage treatment system based on the CASS process according to claim 1 is characterized in that: A reflux pump (4) is arranged in the CASS biochemical reaction pool (2); a water outlet of the reflux pump (4) is connected to a reflux pipe (5); an end of the reflux pipe (5) away from the reflux pump (4) extends into the regulating pool (3) to achieve communication between the regulating pool (3) and the CASS biochemical reaction pool (2).

3. The winter total nitrogen standard-compliant sewage treatment system based on the CASS process according to claim 1 is characterized in that: The regulating tank (3) is used to be connected to an external sewage pipe (01).

4. A winter total nitrogen standard sewage treatment method based on CASS process, characterized by: The winter total nitrogen standard-reaching sewage treatment system based on the CASS process as described in any one of claims 1 to 3 is implemented, comprising: S1: Sewage inflow: connect the external sewage pipe (01) with the water distribution channel (1) so that the external sewage enters the water distribution channel (1); S2: sewage treatment: the sewage in the water distribution channel (1) is introduced into the CASS biochemical reaction pool (2) for aeration, sedimentation and decanting operations in sequence, and the connection state between the water distribution channel (1) and the CASS biochemical reaction pool (2) is controlled so that the connection state between at least two groups of the CASS biochemical reaction pools (2) and the water distribution channel (1) is opposite, so as to achieve continuous water inflow and continuous water outflow of the CASS biochemical reaction pool (2); S3: Reflux of nitrified liquid: When aeration is performed in the CASS biochemical reaction tank (2), the nitrified liquid is pumped into the regulating tank (3), and denitrification reaction is performed by utilizing the anoxic environment formed in the regulating tank (3); S4: Sludge return: The sludge water in the regulating tank (3) is pumped into the water distribution channel (1), and then enters the CASS biochemical reaction tank (2) for sedimentation and decanting; S5: Clean water discharge: The upper clean water that meets the standards after sedimentation in the CASS biochemical reaction tank (2) is decanted to the outside.

5. The winter total nitrogen standard sewage treatment method based on CASS process according to claim 4 is characterized in that: In the step S1, the sewage in the external sewage pipe (01) enters the water distribution channel (1) after passing through the regulating tank (3).

6. The winter total nitrogen standard sewage treatment method based on CASS process according to claim 4 is characterized in that: In the step S3, when the denitrification reaction is carried out in the regulating tank (3), the sewage mixture in the regulating tank (3) is stirred by the stirring mechanism (6) to prevent the sludge in the regulating tank (3) from settling.

7. The winter total nitrogen standard sewage treatment method based on CASS process according to claim 6 is characterized in that: In step S3, a reflux pump (4) is arranged at the rear end of the CASS biochemical reaction tank (2), and the water outlet of the reflux pump (4) is connected to a reflux pipe (5), and one end of the reflux pipe (5) away from the reflux pump (4) extends into the regulating tank (3), so that the nitrified liquid in the CASS biochemical reaction tank (2) can flow into the regulating tank (3).

8. The winter total nitrogen standard sewage treatment method based on CASS process according to claim 7 is characterized in that: The stirring mechanism (6) comprises A mounting frame (61), wherein the mounting frame (61) is mounted on the regulating tank (3); A rotating main shaft (62), the rotating main shaft (62) is rotatably connected to the mounting frame (61), and the rotating axis of the rotating main shaft (62) is vertically arranged; A plurality of stirring rods (63), wherein the stirring rods (63) are connected to the rotating main shaft (62); A driving assembly (64) for driving the rotating main shaft (62) to rotate, wherein the driving assembly (64) is connected to the mounting frame (61), and the driving assembly (64) is connected to the rotating main shaft (62).

9. The winter total nitrogen standard sewage treatment method based on CASS process according to claim 8 is characterized in that: The drive assembly (64) includes A hollow confluence tube (641), the confluence tube (641) is connected to the mounting frame (61), the confluence tube (641) is in communication with an external sewage pipe (01) and a return pipe (5), and the rotating main shaft (62) extends into the confluence tube (641) and is rotatably connected to the confluence tube (641); A plurality of hydraulically driven blades (642) are connected to the rotating main shaft (62), and the hydraulically driven blades (642) are located in the manifold (641), with a rotation gap between the hydraulically driven blades (642) and the manifold (641).

10. The winter total nitrogen standard sewage treatment method based on CASS process according to claim 9 is characterized in that: The rotating main shaft (62) and the stirring rod (63) are both hollow, and a plurality of water inlet holes (621) are provided on the extending section of the rotating main shaft (62) extending into the confluence tube (641), and the water inlet holes (621) are located below the hydraulically driven blades (642), and a plurality of water outlet holes (631) are provided on the stirring rod (63).

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