Sewage treatment system for gradient utilization of phosphorus removal agent

Abstract

The utility model relates to the technical field of sewage treatment, in particular to a sewage treatment system for gradient utilization of a phosphorus removal agent, which comprises an activated sludge treatment unit, a chemical phosphorus removal unit and a control system, the activated sludge treatment unit comprises an anaerobic tank, a first aerobic tank, an anoxic tank, a second aerobic tank, a secondary sedimentation tank and a sludge pump room which are sequentially communicated, and the secondary sedimentation tank is communicated with the chemical phosphorus removal unit. The chemical phosphorus removal unit is communicated with the anaerobic tank and is used for refluxing the sludge containing the phosphorus removal agent into the anaerobic tank. The chemical sludge flows back to the activated sludge unit from the chemical phosphorus removal unit to be utilized for the second time, the utilization rate of the phosphorus removal agent is greatly increased, gradient utilization of the phosphorus removal agent is achieved, and the dosage of the agent is reduced. The control system can treat sewage according to different process routes according to total phosphorus data of inlet and outlet water of the chemical phosphorus removal unit obtained by the on-line monitoring equipment, and automatically control the dosage of phosphorus removal related chemicals.

Description

Technical Field

[0001] The utility model relates to the technical field of sewage treatment, in particular to a sewage treatment system for gradient utilization of phosphorus remover. Background Technique

[0002] In the municipal sewage treatment process, in order to improve the discharge standard of phosphorus, sewage treatment plants generally build upgrading processes. The magnetic coagulation unit, the high-efficiency sedimentation tank unit, etc. are common upgrading processes, which are mainly used for chemical phosphorus removal.

[0003] However, in the actual operation process, in order to ensure that the total phosphorus in the effluent meets the standard, the phosphorus remover often needs to be overdosed, resulting in more unused phosphorus remover in the chemical sludge discharged from the system, thus leading to the waste of the phosphorus remover and the increase of operation cost. Summary of the Utility Model

[0004] The purpose of the utility model is to provide a sewage treatment system for gradient utilization of phosphorus remover, aiming to solve the technical problem that in the existing sewage treatment system, the phosphorus remover is overdosed and the phosphorus remover contained in the sludge discharged from the system is not utilized.

[0005] To achieve the above purpose, the utility model provides a sewage treatment system for gradient utilization of phosphorus remover, which includes an activated sludge treatment unit, a chemical phosphorus removal unit and a control system;

[0006] The activated sludge treatment unit includes an anaerobic tank, a first aerobic tank, an anoxic tank, a second aerobic tank, a secondary sedimentation tank and a sludge pump house connected in sequence. The inlet end and the outlet end of the chemical phosphorus removal unit are respectively provided with a first on-line monitor and a second on-line monitor. The first on-line monitor is used to monitor the total phosphorus data TP of the influent of the chemical phosphorus removal unit in , and the second on-line monitor is used to monitor the total phosphorus data TP of the effluent of the chemical phosphorus removal unit out. . A flow meter is arranged at the inlet end of the chemical phosphorus removal unit, which is used to monitor the influent volume data Q of the chemical phosphorus removal unit in . The first on-line monitor, the second on-line monitor and the flow meter are respectively electrically connected with the control system;

[0007] The chemical phosphorus removal unit is communicated with the anaerobic tank and is used for refluxing the sludge containing phosphorus remover into the anaerobic tank.

[0008] Preferably, the chemical phosphorus removal unit includes a first mixing tank, a second mixing tank, a third mixing tank, a sedimentation tank, a high-shear machine and a magnetic separator connected in sequence through pipelines;

[0009] The first mixing tank is connected to a first chemical dosing pump for adding a phosphorus-removing agent to the first mixing tank; the second mixing tank is connected to a second chemical dosing pump for adding a magnetic powder mixture to the second mixing tank; the third mixing tank is connected to a third chemical dosing pump for adding a flocculant to the third mixing tank. The first chemical dosing pump, the second chemical dosing pump, and the third chemical dosing pump are electrically connected to the control system respectively;

[0010] The sedimentation tank is used for sedimenting the sewage treated by the third mixing tank to obtain sludge containing a phosphorus-removing agent or sludge containing a phosphorus-removing agent and magnetic powder; the high-shear machine is used for crushing the sludge containing a phosphorus-removing agent and magnetic powder; the magnetic separator is used for recovering the magnetic powder in the crushed sludge containing a phosphorus-removing agent and magnetic powder and obtaining sludge containing a phosphorus-removing agent.

[0011] Preferably, the first mixing tank is connected to the third mixing tank through a first pump; the sedimentation tank is connected to the anaerobic tank through a second pump. The first pump and the second pump are electrically connected to the control system respectively;

[0012] A first solenoid valve is installed in the pipeline connecting the first mixing tank and the second mixing tank (sewage flows from the first mixing tank to the second mixing tank by gravity in the pipeline), and the first solenoid valve is electrically connected to the control system; a second solenoid valve is installed in the pipeline connecting the second mixing tank and the third mixing tank (sewage flows from the second mixing tank to the third mixing tank by gravity in the pipeline), and the second solenoid valve is electrically connected to the control system;

[0013] The third mixing tank is connected to the sedimentation tank through a first pipeline; the sedimentation tank is connected to the high-shear machine through a third pump; the high-shear machine is connected to the magnetic separator through a second pipeline; the magnetic separator is connected to the anaerobic tank through a fourth pump. The third pump and the fourth pump are electrically connected to the control system respectively.

[0014] The control system selects different treatment routes by opening and closing each device according to the total phosphorus concentration of the influent water of the chemical phosphorus removal unit.

[0015] Sewage enters the first mixing tank from the secondary sedimentation tank, and when the TP obtained by the first on-line monitor in is less than the preset threshold value, the first pump, the second pump, the first chemical dosing pump, and the third chemical dosing pump are turned on, and the first solenoid valve, the second solenoid valve, the third pump, and the fourth pump are turned off;

[0016] The control system issues a first instruction, and the first chemical dosing pump adds a phosphorus-removing agent to the first mixing tank. Subsequently, the first pump sends the sewage to the third mixing tank, and the third chemical dosing pump adds a flocculant to the third mixing tank. Subsequently, the sewage in the third mixing tank flows by gravity to the sedimentation tank, and the second pump returns the sludge containing the phosphorus-removing agent obtained from the sedimentation tank to the anaerobic tank.

[0017] When the sewage enters the first mixing tank from the secondary sedimentation tank, the TP obtained by the first on-line monitor in ≥ the preset threshold value, the control system issues a second instruction. At this time, the first pump and the second pump are closed, and the first solenoid valve, the second solenoid valve, the first chemical dosing pump, the second chemical dosing pump, the third chemical dosing pump, the third pump, and the fourth pump are opened;

[0018] The sewage flows by gravity from the first mixing tank to the second mixing tank, the third mixing tank, and the sedimentation tank in sequence. The third pump pumps the sewage from the sedimentation tank to the high-shear machine, and the sewage flows by gravity from the high-shear machine to the magnetic separator. The fourth pump returns the sludge containing the phosphorus-removing agent obtained from the magnetic separator to the anaerobic tank.

[0019] Preferably, the control system is used to obtain the total phosphorus data TP of the influent water of the first on-line monitor in 、the total phosphorus data TP of the effluent water of the second on-line monitor out and the influent water flow rate Q of the flowmeter in , and calculate the dosing amounts of the coagulant of the first chemical dosing pump, the magnetic powder of the second chemical dosing pump, and / or the flocculant of the third chemical dosing pump based on this.

[0020] Preferably, the sedimentation tank is an inclined tube sedimentation tank.

[0021] Preferably, the sludge pump house is connected to the anaerobic tank and is used to return the sludge obtained from the secondary sedimentation tank to the anaerobic tank.

[0022] Preferably, a pretreatment unit is further provided at the front end of the anaerobic tank, and the pretreatment unit includes a grille and a grit chamber arranged in sequence.

[0023] The utility model discloses a sewage treatment system for gradient utilization of a phosphorus-removing agent, which has the following beneficial effects: In this solution, the chemical sludge containing the excess phosphorus-removing agent is returned to the activated sludge process unit. The phosphorus-removing agent is used for the first time in the chemical phosphorus-removing unit, and then the chemical sludge is returned from the chemical phosphorus-removing unit to the activated sludge unit for the second time. In the activated sludge unit, the total phosphorus concentration is relatively high, and the reaction between the phosphorus-removing agent and the total phosphorus is thorough. At this time, the utilization rate of the phosphorus-removing agent is greatly improved, realizing the gradient utilization of the phosphorus-removing agent and reducing the dosage of the agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0025] Figure 1 It is a schematic structural diagram of a sewage treatment system using a phosphorus removal agent with gradient utilization according to the present invention;

[0026] Figure 2 It is a schematic structural diagram of the sewage treatment system using a phosphorus removal agent with gradient utilization according to the present invention connected to a control system.

[0027] Figure 3 It is a schematic functional diagram of the control system in the sewage treatment system using a phosphorus removal agent with gradient utilization according to the present invention.

[0028] In the drawings: 1 - activated sludge treatment unit, 11 - anaerobic tank, 12 - first aerobic tank, 13 - anoxic tank, 14 - second aerobic tank, 15 - secondary sedimentation tank, 16 - sludge pump house, 2 - chemical phosphorus removal unit, 21 - first mixing tank, 22 - second mixing tank, 221 - preparation tank, 23 - third mixing tank, 24 - sedimentation tank, 25 - high shear machine, 26 - magnetic separator, 3 - control system, 41 - first on-line monitor, 42 - second on-line monitor, 5 - flow meter, 61 - first pump, 62 - second pump, 63 - third pump, 64 - fourth pump, 71 - first solenoid valve, 72 - second solenoid valve, 81 - first chemical dosing pump, 82 - second chemical dosing pump, 83 - third chemical dosing pump.

[0029] The realization, functional features and advantages of the object of the present invention will be further described with reference to the embodiments and the drawings. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0031] It should be noted that if there are directional indications involved in the embodiments of the present utility model, the directional indications are only used to explain the relative positional relationship, movement conditions, etc. between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0032] In addition, if there are descriptions such as "first" and "second" involved in the embodiments of the present utility model, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present utility model.

[0033] As Figure 1 to Figure 2 shown, a sewage treatment system using a gradient utilization phosphorus remover includes an activated sludge treatment unit 1, a chemical phosphorus removal unit 2, and a control system 3;

[0034] The activated sludge treatment unit 1 includes an anaerobic tank 11, a first aerobic tank 12, an anoxic tank 13, a second aerobic tank 14, a secondary sedimentation tank 15, and a sludge pump house 16 that are connected in sequence. The secondary sedimentation tank 15 is connected to the chemical phosphorus removal unit 2. A first on-line monitor 41 and a second on-line monitor 42 are respectively arranged at the water inlet end and the water outlet end of the chemical phosphorus removal unit 2. The first on-line monitor 41 is used to monitor the total phosphorus data TP of the influent of the chemical phosphorus removal unit 2 in , and the second on-line monitor 42 is used to monitor the total phosphorus data TP of the effluent of the chemical phosphorus removal unit 2 out ;

[0035] A flowmeter 5 is arranged at the water inlet end of the chemical phosphorus removal unit 2, and it is used to monitor the influent volume of the chemical phosphorus removal unit 2. The first on-line monitor 41, the second on-line monitor 42, and the flowmeter 5 are respectively electrically connected to the control system 3;

[0036] The chemical phosphorus removal unit 2 is connected to the anaerobic tank 11 and is used to reflux the sludge containing the phosphorus remover into the anaerobic tank 11.

[0037] This solution provides a sewage treatment system using a novel gradient utilization phosphorus remover. The phosphorus remover is first utilized in the chemical phosphorus removal unit 2, and the total phosphorus is effectively removed. However, the chemical sludge obtained after passing through the chemical phosphorus removal unit 2 still contains some phosphorus removal agents. Therefore, this solution recirculates this part of the chemical sludge back to the activated sludge unit for secondary utilization. In the activated sludge unit, the total phosphorus concentration is relatively high, and the reaction between the phosphorus remover and the total phosphorus is complete, greatly improving the utilization rate of the phosphorus remover, realizing the gradient utilization of the phosphorus remover, and reducing the dosage of the phosphorus removal agent.

[0038] The activated sludge treatment unit 1 of this solution includes an anaerobic tank 11, a first aerobic tank 12, an anoxic tank 13, a second aerobic tank 14, a secondary sedimentation tank 15, and a sludge pump house 16. First, the sewage enters the anaerobic tank 11, where the activated sludge decomposes macromolecular organic matter into small-molecular organic matter and releases the phosphorus element stored in the cells at the same time. Then it is continuously transported to the first aerobic tank 12, where the activated sludge degrades the macromolecular organic matter into carbon dioxide and water, converts ammonia nitrogen into nitrate nitrogen, and absorbs phosphorus element at the same time. The amount of phosphorus element absorbed here is more than that released in the anaerobic tank 11. It is then transported to the anoxic tank 13, where the activated sludge converts nitrate nitrogen into nitrogen gas. Then, in the second aerobic tank 14, the activated sludge further degrades organic matter and ammonia nitrogen. Finally, in the secondary sedimentation tank 15, the activated sludge and water are separated, the effluent enters the chemical phosphorus removal unit 2, and the activated sludge enters the sludge pump house 16.

[0039] Furthermore, the chemical phosphorus removal unit 2 includes a first mixing tank 21, a second mixing tank 22, a third mixing tank 23, a sedimentation tank 24, a high-shear machine 25, and a magnetic separator 26 that are connected in sequence through pipelines;

[0040] The first mixing tank 21 is connected to a first dosing pump 81, and the first dosing pump 81 is used to add a phosphorus remover to the first mixing tank 21; the second mixing tank 22 is connected to a second dosing pump 82, and the second dosing pump 82 is used to add a magnetic powder mixture to the second mixing tank 22; the third mixing tank 23 is connected to a third dosing pump 83, and the third dosing pump 83 is used to add a flocculant to the third mixing tank 23. The first dosing pump 81, the second dosing pump 82, and the third dosing pump 83 are respectively electrically connected to the control system 3;

[0041] The sedimentation tank 24 is used to separate the mud-water mixture processed by the third mixing tank 23 and obtain sludge, which contains a phosphorus remover or contains a phosphorus remover and magnetic powder; the high-shear machine 25 is used to break up the sludge containing a phosphorus remover and magnetic powder; the magnetic separator 26 is used to recover the magnetic powder in the broken sludge containing a phosphorus remover and magnetic powder and obtain sludge containing a phosphorus remover.

[0042] As Figure 1As shown in the figure, the effluent of the secondary sedimentation tank 15 is pumped by the pump body of the sludge pump house 16 to the first mixing tank 21. A liquid phosphorus remover is added to the first mixing tank 21, and a magnetic powder mixture (the second mixing tank 22 is connected to the preparation tank 221 for preparing the magnetic powder mixture, and the magnetic powder mixture refers to a mixture of magnetic powder and other liquids, such as water, etc.) is added to the second mixing tank 22. A liquid flocculant is added to the third mixing tank 23. After the sewage passes through the first mixing tank 21, the second mixing tank 22 and the third mixing tank 23 in sequence, it then enters the sedimentation tank 24. The sedimentation tank 24 can separate the mud and water from the incoming mixed liquid. The effluent after separation leaves the chemical phosphorus removal unit 2 and is discharged after filtration and disinfection treatment. The chemical sludge containing the phosphorus remover and magnetic powder obtained after separation is then further broken by a high-shear machine 25, and the magnetic powder therein is recovered by a magnetic separator 26.

[0043] Furthermore, the first mixing tank 21 is connected to the third mixing tank 23 through a first pump 61. The sedimentation tank 24 is connected to the anaerobic tank 11 through a second pump 62. The first pump 61 and the second pump 62 are respectively electrically connected to the control system 3.

[0044] A first electromagnetic valve 71 is installed in the pipeline connecting the first mixing tank 21 and the second mixing tank 22, and the first electromagnetic valve 71 is electrically connected to the control system 3. A second electromagnetic valve 72 is installed in the pipeline connecting the second mixing tank 22 and the third mixing tank 23, and the second electromagnetic valve 72 is electrically connected to the control system 3.

[0045] The third mixing tank 23 is connected to the sedimentation tank 24 through a first pipeline. The sedimentation tank 24 is connected to the high-shear machine 25 through a third pump 63. The high-shear machine 25 is connected to the magnetic separator 26 through a second pipeline. The magnetic separator 26 is connected to the anaerobic tank 11 through a fourth pump 64. The third pump 63 and the fourth pump 64 are respectively electrically connected to the control system 3.

[0046] Furthermore, when the TP of the sewage entering the first mixing tank 21 obtained by the first on-line monitor 41 in is less than the preset threshold value, the control system 3 issues a first instruction, and the first pump 61, the second pump 62, the first chemical dosing pump 81, and the third chemical dosing pump 83 are turned on, while the first electromagnetic valve 71, the second electromagnetic valve 72, the third pump 63, and the fourth pump 64 are turned off.

[0047] The first chemical dosing pump 81 adds a phosphorus-removing agent to the first mixing tank 21. Subsequently, the first pump 61 pumps the sewage into the third mixing tank 23, and the third chemical dosing pump 83 adds a flocculant to the third mixing tank 23. Subsequently, the sewage flows by gravity to the sedimentation tank 24, and the second pump 62 returns the phosphorus-removing agent-containing sludge obtained from the sedimentation tank 24 to the anaerobic tank 11.

[0048] Specifically, when TP in < the preset threshold, that is, when the total phosphorus in the influent is relatively low, such as less than 1.5 mg / L, the control system 3 issues a first command to turn on line A. The sewage enters the chemical phosphorus removal unit 2, flows through the first mixing tank 21 and the third mixing tank 23, and then enters the sedimentation tank 24 for sedimentation separation. The effluent after separation leaves the chemical phosphorus removal unit 2, is filtered and disinfected, and then discharged. The chemical sludge containing the phosphorus-removing agent obtained after separation is pumped by the second pump 62 to the anaerobic tank 11.

[0049] Further, when the TP of the sewage entering the first mixing tank 21 obtained by the first on-line monitor 41 in ≥ the preset threshold, the control system 3 issues a second command to turn off the first pump 61 and the second pump 62, and turn on the first solenoid valve 71, the second solenoid valve 72, the first chemical dosing pump 81, the second chemical dosing pump 82, the third chemical dosing pump 83, the third pump 63, and the fourth pump 64;

[0050] The sewage flows by gravity from the first mixing tank 21 to the second mixing tank 22, the third mixing tank 23, and the sedimentation tank 24. The third pump 63 pumps the sewage from the sedimentation tank 24 to the high-shear machine 25, and the sewage flows by gravity from the high-shear machine 25 to the magnetic separator 26. The fourth pump 64 returns the phosphorus-removing agent-containing sludge obtained from the magnetic separator 26 to the anaerobic tank 11.

[0051] Specifically, when TP in ≥ the preset threshold, that is, when the total phosphorus in the influent is relatively high, such as more than 1.5 mg / L, the control system 3 issues a first command to turn on line B. The sewage enters the chemical phosphorus removal unit, flows through the first mixing tank 21, the second mixing tank 22, and the third mixing tank 23, and then enters the sedimentation tank 24 for sedimentation separation. The effluent after separation leaves the chemical phosphorus removal unit 2, is filtered and disinfected, and then discharged. The chemical sludge containing the phosphorus-removing agent and magnetic powder obtained after separation is pumped by the third pump 63 to the high-shear machine 25. The high-shear machine 25 breaks up the sludge, and then the sludge enters the magnetic separator 26. The magnetic separator 26 recovers the magnetic powder, and then the fourth pump 64 pumps the phosphorus-removing agent-containing sludge obtained from the magnetic separator 26 to the anaerobic tank 11.

[0052] The differences between the above two return lines of sludge containing phosphorus removal agent are as follows: When the total phosphorus at the water outlet end of the secondary sedimentation tank 15 (i.e., the water inlet end of the first mixing tank 21) is low, line A is opened, and the sewage only needs to undergo coagulation and flocculation treatment to meet the control requirements; when the total phosphorus at the water outlet end of the secondary sedimentation tank 15 (i.e., the water inlet end of the first mixing tank 21) is high, line B is opened, and the sewage can meet the control requirements after coagulation, magnetic coagulation, and flocculation treatment. Different lines correspond to different treated water concentrations, which can effectively reduce the usage amount of magnetic powder and the operation time of related stirring, shearing, and separation equipment, and reduce the usage amount of chemicals and power consumption of equipment.

[0053] The above two return lines of sludge containing phosphorus removal agent can further improve the utilization rate of the phosphorus removal agent. The phosphorus removal agent is first utilized in the first mixing tank 21, the second mixing tank 22, and the third mixing tank 23, but there is still residual phosphorus removal agent in the chemical sludge subsequently. This part of the phosphorus removal agent will enter the system again through the above two return routes to achieve secondary utilization.

[0054] The sludge containing phosphorus removal agent discharged from the sedimentation tank 24 or the magnetic separator 26 is returned to the anaerobic tank 11. Since the total phosphorus concentration in the activated sludge treatment unit 1 is high, according to the reaction equilibrium equation of the phosphorus removal agent and phosphate (taking iron salt as an example): Fe 3+ +PO4 3- →FePO4↓. In the case of a high total phosphorus concentration, the reaction equilibrium of the phosphorus removal agent always moves to the right until all the phosphorus removal agent has reacted. Therefore, the utilization rate of the phosphorus removal agent in this system is significantly improved compared with that of ordinary chemical phosphorus removal systems.

[0055] Furthermore, a first on-line monitor 41 and a second on-line monitor 42 are respectively arranged at the water inlet end and the water outlet end of the chemical phosphorus removal unit 2, which are respectively used to monitor the total phosphorus data TP in of the influent of the chemical phosphorus removal unit 2 and the total phosphorus data TP out. of the effluent. A flow meter 5 is arranged at the water inlet end of the chemical phosphorus removal unit 2, which is used to monitor the influent water volume data Q in of the chemical phosphorus removal unit 2. The first on-line monitor 41, the second on-line monitor 42, and the flow meter 5 are respectively electrically connected to the control system 3;

[0056] As Figure 3 shown, through the system of this solution, the dosing amounts of the phosphorus removal agent and magnetic powder can be controlled according to the total phosphorus of the influent, the influent water volume, the set value of the total phosphorus of the effluent, and the total phosphorus of the effluent of the chemical phosphorus removal unit 2. Specifically, the control system 3 is used to control how much chemical dosage each dosing pump adds to each mixing tank:

[0057] First, a first on-line monitor 41 and a second on-line monitor 42 are installed at the water inlet end and the water outlet of the chemical phosphorus removal unit 2, which can respectively obtain the total phosphorus data TP at the water inlet end in and the total phosphorus data TP at the water outlet end out (the data is read every 40 minutes). A flow meter 5 is also installed at the water inlet end of the chemical phosphorus removal unit 2, which can obtain the influent flow rate data Q of the chemical phosphorus removal unit in .

[0058] Furthermore, set the total phosphorus value TP at the water outlet of the chemical phosphorus removal unit 2 set . The control system 3 calculates the dosage of the phosphorus removal agent at this time according to the influent flow rate data Q in and the total phosphorus data TP in . When the total phosphorus data TP at the water outlet end out exceeds TP set by 20%, increase the dosage of the phosphorus removal agent. The dosage of the phosphorus removal agent is proportional to the product of the influent flow rate and the influent total phosphorus, and the proportionality coefficient needs to be determined through bench-scale experiments

[0059] Furthermore, the control system 3 sets the dosages of the magnetic powder and the flocculant according to the influent flow rate data Q in . The dosages of the magnetic powder and the flocculant are proportional to the influent flow rate, and the proportionality coefficient needs to be determined through bench-scale experiments

[0060] Furthermore, since the subsequent chemical sludge will flow back to the anaerobic tank 11, therefore, this solution preferably uses iron salts as the liquid phosphorus removal agent. Of course, other agents with less inhibition on the activity of activated sludge can also be added as the phosphorus removal agent

[0061] Furthermore, the sedimentation tank 24 is an inclined tube sedimentation tank. The inclined tube sedimentation tank has the following advantages: the sedimentation area is larger than that of the conventional sedimentation; the sedimentation efficiency is high, and it has a good sludge sedimentation effect when used in this system

[0062] Furthermore, the sludge pump house 16 is connected to the anaerobic tank 11 and is used to return the sludge obtained from the secondary sedimentation tank 15 to the anaerobic tank 11. A return path is also set in the activated sludge unit. Specifically, part of the sludge obtained from the secondary sedimentation tank 15 is returned to the anaerobic tank 11 by the pump body of the sludge pump house 16 to supplement the number of microorganisms in the activated sludge process unit. The return ratio is 50% - 150%, and the excess sludge obtained from the secondary sedimentation tank 15 is discharged out of the system

[0063] Furthermore, a pretreatment unit (not shown in the figure) is also provided at the front end of the anaerobic pond 11. The pretreatment unit includes a grille and a grit chamber arranged in sequence. The pretreatment unit can remove impurities in the sewage at the front end. The sewage first passes through the grille, and the grille filters out large-sized impurities in the sewage. Then the sewage enters the grit chamber. After staying in the grit chamber for a period of time, sand grains or other relatively small-sized impurities can be removed.

[0064] Embodiment

[0065] The influent and effluent water quality of a certain municipal sewage treatment plant is as follows in the table:

[0066]

[0067] The original treatment process of this sewage treatment plant is: pretreatment → anaerobic pond → anoxic pond → aerobic pond → secondary sedimentation tank → sludge pump house → chemical phosphorus removal unit → precision filtration unit → disinfection unit → effluent. A part of the magnetic coagulation sludge is recycled to the chemical phosphorus removal unit, and a part is discharged as surplus sludge. The utilization efficiency of the phosphorus removal agent is relatively low.

[0068] The adjusted process using the sewage treatment system for gradient utilization of the phosphorus removal agent in this solution is: pretreatment unit → anaerobic pond 11 → first aerobic pond 12 → anoxic pond 13 → second aerobic pond 14 → secondary sedimentation tank 15 → sludge pump house 16 → chemical phosphorus removal unit 2 → precision filtration unit → disinfection unit → effluent. All the sludge obtained from the chemical phosphorus removal unit 2 is recycled to the anaerobic pond 11. At the same time, the phosphorus removal agent, magnetic powder, and flocculant are automatically added, and the utilization rate of the phosphorus removal agent is greatly improved.

[0069] The usage amounts of the phosphorus removal agent, magnetic powder, and flocculant before and after the transformation are as follows in the table:

[0070]

[0071] In summary, comparing before and after the transformation, in the case where the total phosphorus concentration of the influent water of the treatment system in this solution increases by 21%, the usage amount of the phosphorus removal agent (polyferric sulfate) is reduced by 24%, and the usage amount of PAM is reduced by 33%.

[0072] The above are only the preferred embodiments of the present invention, and thus do not limit the patent scope of the present invention. Any equivalent structural transformation made under the inventive concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A sewage treatment system using a gradient phosphorus removal agent, characterized in that, It includes an activated sludge treatment unit (1), a chemical phosphorus removal unit (2) and a control system (3); The activated sludge treatment unit (1) includes an anaerobic tank (11), a first aerobic tank (12), an anoxic tank (13), a second aerobic tank (14), a secondary sedimentation tank (15), and a sludge pump house (16) that are connected in sequence. The secondary sedimentation tank (15) is connected to the chemical phosphorus removal unit (2). A first on-line monitor (41) and a second on-line monitor (42) are respectively arranged at the water inlet end and the water outlet end of the chemical phosphorus removal unit (2). The first on-line monitor (41) is used to monitor the total phosphorus data TP of the influent water of the chemical phosphorus removal unit (2). in The second on-line monitor (42) is used to monitor the total phosphorus data TP of the effluent water of the chemical phosphorus removal unit (2). out A flow meter (5) is further arranged at the water inlet end of the chemical phosphorus removal unit (2), and it is used to monitor the influent water volume data Q of the chemical phosphorus removal unit (2). in The first on-line monitor (41), the second on-line monitor (42), and the flow meter (5) are respectively electrically connected to the control system (3). The chemical phosphorus removal unit (2) is communicated with the anaerobic tank (11) and is used for refluxing the sludge containing a phosphorus removal agent into the anaerobic tank (11).

2. The sewage treatment system using a phosphorus removal agent with gradient utilization according to claim 1, characterized in that, The chemical phosphorus removal unit (2) includes a first mixing tank (21), a second mixing tank (22), a third mixing tank (23), a sedimentation tank (24), a high shear machine (25) and a magnetic separator (26) which are sequentially communicated through pipelines; The first mixing tank (21) is communicated with a first chemical dosing pump (81), and the first chemical dosing pump (81) is used for dosing a phosphorus removal agent into the first mixing tank (21); the second mixing tank (22) is communicated with a second chemical dosing pump (82), and the second chemical dosing pump (82) is used for dosing a magnetic powder mixture into the second mixing tank (22); the third mixing tank (23) is communicated with a third chemical dosing pump (83), and the third chemical dosing pump (83) is used for dosing a flocculant into the third mixing tank (23). The first chemical dosing pump (81), the second chemical dosing pump (82) and the third chemical dosing pump (83) are respectively electrically connected with the control system (3); The sedimentation tank (24) is used for sedimenting the sewage treated by the third mixing tank (23) and obtaining the sludge containing a phosphorus removal agent or the sludge containing a phosphorus removal agent and magnetic powder; the high shear machine (25) is used for crushing the sludge containing a phosphorus removal agent and magnetic powder; the magnetic separator (26) is used for recovering the magnetic powder in the crushed sludge containing a phosphorus removal agent and magnetic powder and obtaining the sludge containing a phosphorus removal agent.

3. The sewage treatment system using a gradient phosphorus removal agent according to claim 2, characterized in that, The first mixing tank (21) is communicated with the third mixing tank (23) through a first pump (61), the sedimentation tank (24) is communicated with the anaerobic tank (11) through a second pump (62), and the first pump (61) and the second pump (62) are respectively electrically connected with the control system (3); A first solenoid valve (71) is installed in the pipeline connecting the first mixing tank (21) and the second mixing tank (22), and the first solenoid valve (71) is electrically connected with the control system (3); a second solenoid valve (72) is installed in the pipeline connecting the second mixing tank (22) and the third mixing tank (23), and the second solenoid valve (72) is electrically connected with the control system (3); The third mixing tank (23) is communicated with the sedimentation tank (24) through a first pipeline, the sedimentation tank (24) is communicated with the high shear machine (25) through a third pump (63), the high shear machine (25) is communicated with the magnetic separator (26) through a second pipeline, and the magnetic separator (26) is communicated with the anaerobic tank (11) through a fourth pump (64). The third pump (63) and the fourth pump (64) are respectively electrically connected with the control system (3).

4. A sewage treatment system using a gradient phosphorus removal agent according to claim 3, characterized in that, The sewage TP entering the first mixing tank (21) obtained by the first on-line monitor (41) in When it is less than the preset threshold, the control system (3) issues a first instruction, and the first pump (61), the second pump (62), the first chemical dosing pump (81) and the third chemical dosing pump (83) are used to be respectively turned on when receiving the first instruction, and the first solenoid valve (71), the second solenoid valve (72), the third pump (63) and the fourth pump (64) are used to be respectively turned off when receiving the first instruction; So that the first chemical dosing pump (81) doses a phosphorus-removing agent into the first mixing tank (21), the first pump (61) pumps sewage into the third mixing tank (23), and the third chemical dosing pump (83) doses a flocculant into the third mixing tank (23); the sewage in the third mixing tank (23) is transported to the sedimentation tank (24) through the first pipeline, and the second pump (62) returns the phosphorus-removing agent-containing sludge obtained from the sedimentation tank (24) to the anaerobic tank (11).

5. The sewage treatment system using a gradient phosphorus removal agent according to claim 3, characterized in that, The TP of the sewage entering the first mixing tank (21) obtained by the first on-line monitor (41) in When it is ≥ the preset threshold, the control system (3) issues a second instruction, and the first pump (61) and the second pump (62) are used to close respectively when receiving the second instruction, and the first solenoid valve (71), the second solenoid valve (72), the first chemical dosing pump (81), the second chemical dosing pump (82), the third chemical dosing pump (83), the third pump (63) and the fourth pump (64) are used to open respectively when receiving the second instruction; So that sewage is sequentially transported from the first mixing tank (21) to the second mixing tank (22), the third mixing tank (23) and the sedimentation tank (24), the third pump (63) pumps sewage from the sedimentation tank (24) to the high-shear machine (25), the sewage is transported from the high-shear machine (25) to the magnetic separator (26), and the fourth pump (64) returns the phosphorus-removing agent-containing sludge obtained from the magnetic separator (26) to the anaerobic tank (11).

6. A sewage treatment system using a gradient phosphorus removal agent according to claim 4 or 5, characterized in that The control system (3) is used to obtain the total phosphorus data TP of the influent water of the first on-line monitor (41). in and the total phosphorus data TP of the effluent water of the second on-line monitor (42). out and the influent water flow rate Q of the flowmeter (5). in And based on these, calculate the dosage of the coagulant of the first chemical dosing pump (81), the magnetic powder of the second chemical dosing pump (82), and / or the flocculant of the third chemical dosing pump (83).

7. A sewage treatment system using a gradient phosphorus removal agent according to claim 2, characterized in that, The sedimentation tank (24) is an inclined-tube sedimentation tank.

8. A sewage treatment system using a phosphorus removal agent with gradient utilization according to claim 1, characterized in that, The sludge pump house (16) communicates with the anaerobic tank (11) and is used to return the sludge obtained from the secondary sedimentation tank (15) to the anaerobic tank (11).

9. The sewage treatment system using a gradient phosphorus removal agent according to claim 1, characterized in that, A pretreatment unit is further provided at the front end of the anaerobic tank (11), and the pretreatment unit includes a grille and a grit chamber arranged in sequence.

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