MBR process with high membrane flux and high phosphorus removal efficiency

Abstract

The present application relates to sewage treatment technical field, disclose a kind of MBR process with high membrane flux and high-efficiency phosphorus removal, the MBR process is between aerobic zone and MBR membrane pool Setting flow guide area and sedimentation area;Flow guide area and aerobic zone between being equipped with flow guide wall flow guide wall being equipped with flow guide hole, flow guide area and sedimentation area between being equipped with partition wall, water inlet being opened in the upper portion of partition wall, the sewage of flow guide area is buffered to the aerobic zone into sedimentation area;Sedimentation area and MBR membrane pool between being equipped with triangular weir plate, the sewage before entering MBR membrane pool is treated by sedimentation in sedimentation area, to reduce the membrane pollution speed, extend the service life of membrane group device.The MBR process with high membrane flux and high-efficiency phosphorus removal is mainly to the postpositioned anoxic section of biochemical reaction tank is reformed, without new building, by increasing some equipment and to postpositioned anoxic section local reformation can be realized, save operating cost, reduce the membrane pollution speed, extend the service life of membrane group device.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to an MBR process with high membrane flux and efficient phosphorus removal. Background Technology

[0002] MBR (Membrane Bioreactor) technology, as a highly efficient wastewater treatment process, is widely used in wastewater treatment in various cities. MBR technology has the following advantages: replacing secondary sedimentation tanks with membrane tanks eliminates the need to consider filter depth, significantly saving construction costs and land use; furthermore, it produces better effluent quality, has strong shock resistance, maintains a longer sludge age, which is conducive to the growth and reproduction of slow-growing nitrifying bacteria; and it is easy to automate control, making operation and management convenient.

[0003] While MBR membrane technology has significant advantages, it also has some insurmountable drawbacks, which are as follows:

[0004] (1) The biggest drawback is that the membrane module needs to be replaced regularly, generally every 5 to 8 years. The replacement cost of the membrane module is relatively high. If it is not replaced, the membrane flux will become worse and worse with the increase of usage time, and it will not be able to meet the water production demand. (2) During the daily use of the membrane module, suspended pollutants, dissolved organic matter, and microorganisms in the mixed liquor will form deposits on the membrane surface. At the same time, fibers and debris in the activated sludge will fold and become entangled. Both of these will cause membrane fouling and reduce the membrane permeability to varying degrees. (3) The membrane module needs to be maintained regularly, that is, the membrane of the membrane module needs to be cleaned online and offline regularly to reduce the rate of membrane fouling. The regular maintenance of the membrane module increases the operating cost. Summary of the Invention

[0005] To address the above problems, this invention provides an MBR process with high membrane flux and efficient phosphorus removal.

[0006] The technical solution adopted in this invention is as follows:

[0007] A high-flux, high-efficiency phosphorus removal MBR process is disclosed. The MBR process includes: utilizing an anaerobic zone for organic matter degradation, nitrogen removal, and sulfide degradation in wastewater to achieve preliminary purification and biological waterproofing; utilizing an anoxic zone for secondary organic matter degradation, secondary nitrogen removal, and sulfur and nitrate reduction in wastewater to achieve filter material regeneration and reasonable control of sludge production; utilizing an aerobic zone for biological oxidation, tertiary nitrogen removal, and abnormal gas removal in wastewater to achieve abnormal gas removal, biological decomposition of COD and BOD in wastewater, and biofilm reconstruction; and utilizing the membrane modules of the MBR membrane tank for final solid-liquid separation and biological treatment of wastewater.

[0008] This MBR process also includes a flow guide zone and a sedimentation zone between the aerobic zone and the MBR membrane tank;

[0009] The diversion zone is a pool structure, with a diversion wall between it and the aerobic zone, and a partition wall between it and the sedimentation zone. The diversion wall has diversion holes, and an inlet is opened at the top of the partition wall. A return pump is installed in the pool of the diversion zone. Wastewater in the aerobic zone enters the diversion zone through the diversion holes on the diversion wall, and some wastewater is returned to the inlet of the anoxic zone by the return pump. After being buffered by the diversion zone, the wastewater enters the sedimentation zone through the inlet at the top of the partition wall.

[0010] The sedimentation zone is also a tank structure, with several triangular weir plates between it and the MBR membrane tank. The bottom of the sedimentation zone is equipped with a sludge discharge pipe and a sludge discharge pump installed on the sludge discharge pipe. Wastewater is removed by sedimentation in the sedimentation zone, and the supernatant of the wastewater in the sedimentation zone enters the MBR membrane tank through the triangular weir plates.

[0011] Furthermore, the pool volume of the guide zone is calculated using the following formula:

[0012]

[0013] In the formula, T is the sedimentation time; q is the influent flow rate; L is the total length of the tank; H is the depth of the tank; and B is the width of the tank.

[0014] Furthermore, the flow rate of the diversion zone is calculated using the following formula:

[0015] The flow rate in the diversion zone is Q = q × (1 + R).

[0016] In the formula, q is the influent flow rate; R is the recirculation ratio.

[0017] The number of guide holes on the guide wall and the diameter of the guide holes are determined by calculating the water flow rate.

[0018] Furthermore, the volume of the sedimentation zone is calculated using the following formula:

[0019] Sedimentation tank volume V1 = T × q

[0020] In the formula, T is the settling time; q is the influent flow rate q (m³). 3 / h).

[0021] Furthermore, the flow rate between the sedimentation zone and the MBR membrane tank is equal to the hourly inflow rate when both return pumps are turned on simultaneously, i.e., the maximum design flow rate.

[0022] Furthermore, the triangular weir plate of the sedimentation zone is calculated using the following formula:

[0023]

[0024] The outlet weir adopts a 90-degree triangular weir, with N weir openings per meter of weir plate;

[0025]

[0026] The water head above the weir is h1 = (q1 / 1.4) (2 / 5) ;

[0027] The width of the water collection tank, B, is calculated as follows: B = 0.9 × (maximum design flow rate × 1.3). (1 / 3) ;

[0028] The water depth at the beginning of the collection tank, h0, is 1.73 × the critical water depth h of the collection tank. k ;

[0029] The free fall height from the outlet tank is h2;

[0030] Total depth of the water collection tank = h0 + h1 + h2.

[0031] Furthermore, a first dosing pipe is provided on the side of the sedimentation zone near the flow guide zone, and a second dosing pipe 18 is provided in the MBR membrane tank; phosphorus removal agent can be added to the sedimentation zone and the MBR membrane tank individually or simultaneously through the first and second dosing pipes.

[0032] Furthermore, the amount of phosphorus removal agent to be added to the sedimentation zone is calculated using the following formula:

[0033] When iron salts are used as phosphorus removal agents:

[0034] m = 2.7 × (C0 - C) × Q

[0035] When aluminum salts are used as dephosphorizing agents:

[0036] m = 1.3 × (C0 - C) × Q

[0037] In the formula, m is the mass of the reagent; C0 is the total phosphorus concentration in the influent, C is the total phosphorus concentration in the effluent, and Q is the water volume.

[0038] The beneficial effects of this invention are:

[0039] 1. This MBR process utilizes the existing anaerobic zone and MBR membrane tank in wastewater treatment processes, modifying only the post-anoxic section of the biological reactor. A flow guide zone and a sedimentation zone are set up between the aerobic zone and the MBR membrane tank. The flow guide zone buffers the wastewater entering the sedimentation zone from the aerobic zone, while the sedimentation zone treats the wastewater before it enters the MBR membrane tank. This effectively removes a large amount of sludge and solid pollutants, reducing the membrane tank's filtration load, significantly alleviating membrane fouling, increasing permeate flow, extending the membrane module replacement cycle, ensuring membrane permeability, and reducing membrane module maintenance frequency, thereby saving operating costs.

[0040] 2. The MBR process is relatively simple to modify. Individual tanks can be modified separately without affecting production. No new buildings need to be added during the modification process. It can be achieved by adding some equipment and making local modifications to the post-anoxic section. The modification cost is low and no new operating costs need to be added after the modification.

[0041] 3. The MBR process has dosing pipes installed on the side of the sedimentation zone near the flow guide zone and in the MBR membrane tank. Phosphorus removal agent can be added to multiple points in the sedimentation zone and the MBR membrane tank through the dosing pipes. Combined with the microfiltration performance of the membrane itself, particulate total phosphorus in the water can be significantly removed, thereby improving phosphorus removal efficiency. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the overall layout of the MBR process of this invention;

[0043] Figure 2 This is a schematic diagram of the flow guiding zone and sedimentation zone in the MBR process of this invention;

[0044] Figure 1 —2, 1—Anaerobic zone, 2—Anoxic zone, 3—Aerobic zone, 4—MBR membrane tank, 5—Membrane module, 6—Flow guiding zone, 7—Sedimentation zone, 8—Flow guiding wall, 9—Partition wall, 10—Flow guiding hole, 11—Inlet, 12—Recirculation pump, 13—Triangular weir plate, 14—Sludge discharge pipe, 15—Sludge discharge pump, 16—Aeration disc, 17—Sewage discharge pipe, 18—Agitator, 19—First chemical dosing pipe, 20—Second chemical dosing pipe. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0046] Example 1

[0047] This embodiment provides an MBR process with high membrane flux and efficient phosphorus removal. The MBR process uses the anaerobic zone 1 and MBR membrane tank 4 in the existing sewage treatment process, and only modifies the post-anoxic section of the biological reaction tank. Without changing the land area, the anoxic zone and aerobic zone are converted into anoxic zone 2, aerobic zone 3, diversion zone 6 and sedimentation zone 7.

[0048] like Figure 1As shown, wastewater first enters anaerobic zone 1 through sewage pipe 17. In anaerobic zone 1, the wastewater is stirred by a mixer 18, undergoing organic matter degradation, nitrogen removal, and sulfide degradation, achieving preliminary purification and biological waterproofing. The wastewater treated in anaerobic zone 1 then enters anoxic zone 2, which is equipped with a mixer 18 and a return pump 12. In anoxic zone 2, the wastewater undergoes secondary organic matter degradation, secondary nitrogen removal, and sulfur and nitrate reduction, achieving filter material regeneration and reasonable control of sludge production. The wastewater treated in anoxic zone 2 then enters aerobic zone 3, which contains aerobic tank I and aerobic tank II. In aerobic tank I and aerobic tank II, the wastewater undergoes biological oxidation, tertiary nitrogen removal, and abnormal gas removal through aeration discs 16, achieving abnormal gas removal, biological decomposition of COD and BOD in the wastewater, and biofilm reconstruction.

[0049] The wastewater treated in aerobic zone 3 is diverted through diversion zone 6 and then enters sedimentation zone 7. For example... Figure 1 and Figure 2 As shown, the diversion zone 6 is a pool structure. A diversion wall 8 is provided between the pool body of the diversion zone 6 and the aerobic pool II. A diversion hole 10 is provided at the lower part of the diversion wall 8, allowing the wastewater in the aerobic pool II to enter the pool body of the diversion zone 6 through the diversion hole 10. At the same time, a return pump 12 is installed in the pool body of the diversion zone, which causes some of the wastewater to return to the inlet end of the anoxic zone 2. A partition wall 9 is provided between the pool body of the diversion zone 6 and the sedimentation zone 7. An inlet 11 is opened at the upper part of the partition wall 9. Since the inlet 11 of the partition wall 9 is higher than the diversion hole 10 of the diversion wall 8, the diversion zone 6 adopts a low-level inlet and high-level outlet method, allowing the wastewater in the aerobic pool II to enter the pool body of the diversion zone 6. The wastewater is buffered in the pool body of the diversion zone 6 before entering the sedimentation zone 7.

[0050] like Figure 1 and Figure 2 The sedimentation zone 7 is also a tank structure. Several triangular weirs 13 are installed between the sedimentation zone 7 and the MBR membrane tank 4. A sludge discharge pipe 14 and a sludge discharge pump 15 are installed at the bottom of the sedimentation zone. The sludge discharge pipe 14 can share a set with the MBR membrane tank 4. Wastewater is buffered in the diversion zone 6 before entering the sedimentation zone 7, where sedimentation removes sludge. The supernatant from the wastewater in the sedimentation zone 7 enters the MBR membrane tank 4 through the triangular weirs 13. Because the sludge concentration in the supernatant is low, the filtration load on the MBR membrane tank 4 is reduced, significantly alleviating membrane fouling, increasing permeate production, extending the replacement cycle of the membrane modules 5 in the MBR membrane tank 4, ensuring the permeability of the membrane modules 5, reducing the maintenance frequency of the membrane modules 5, and saving operating costs. When the sludge in the sedimentation zone 7 reaches a certain level, the sludge discharge pump 15 can be activated to discharge the sludge from the bottom of the sedimentation zone 7 through the sludge discharge pipe 14.

[0051] Furthermore, before modifying the post-anoxic section of the biological reactor, the MBR process must calculate the corresponding tank volume and wastewater flow rate. Based on the calculated tank volume and wastewater flow rate, the corresponding modifications to the anoxic zone 2, aerobic zone 3, diversion zone 6, and sedimentation zone 7 are then carried out, as detailed below:

[0052] 1. Pool size design:

[0053] Since the floor area and volume of anaerobic zone 1 and MBR membrane tank 4 remain unchanged throughout the entire renovation process, they are known quantities. Based on these two known quantities, the volume of anoxic zone 2, aerobic zone 3, diversion zone 6 and sedimentation zone 7 can be calculated.

[0054]

[0055] In the formula, T is the settling time, taken as 1.5-2 hours; q is the influent flow rate, in cubic meters per second (m³). 3 / h; L is the total length of the pool, in meters; H is the depth of the pool, in meters; B is the width of the pool, in meters.

[0056] Sedimentation tank volume: V1=T×q

[0057] In the formula, T is the sedimentation time, taken as 1.5-2 hours; q is the influent flow rate, in cubic meters per second (m³). 3 / h.

[0058] The ratio of the volume of the diversion zone to the sedimentation zone is approximately 1:2.

[0059] With the volumes of the diversion zone and sedimentation zone already determined, the volumes of the anoxic zone and aerobic zone are determined based on actual needs.

[0060] II. Wastewater Flow Design:

[0061] The flow rate of the diversion zone is calculated using the following formula:

[0062] The flow rate in the diversion zone is Q = q × (1 + R).

[0063] In the formula, q is the influent flow rate; R is the recirculation ratio.

[0064] The flow rate between the sedimentation tank and the MBR membrane tank is equal to the hourly inflow rate when both return pumps are turned on simultaneously, which is the maximum design flow rate.

[0065] The triangular weir plate of the sedimentation zone is calculated using the following formula:

[0066]

[0067] The outlet weir adopts a 90-degree triangular weir, with N weir openings per meter of weir plate;

[0068]

[0069] The water head above the weir is h1 = (q1 / 1.4) (2 / 5) ;

[0070] The width of the water collection tank, B, is calculated as follows: B = 0.9 × (maximum design flow rate × 1.3). (1 / 3) ;

[0071] The water depth at the beginning of the collection tank, h0, is 1.73 × the critical water depth h of the collection tank. k ;

[0072] The free fall height from the outlet tank is h2;

[0073] Total depth of the water collection tank = h0 + h1 + h2.

[0074] In the actual modification process, the tanks of anoxic zone 2, aerobic zone 3, diversion zone 6, and sedimentation zone 7 can be modified one by one without affecting the normal operation of the water plant. After the modification, the residence time of sewage in anaerobic zone 1, anoxic zone 2, and aerobic zone 3 remains unchanged. The sewage in anaerobic zone 1 only needs to be stirred to control the dissolved oxygen content of the sewage to 0.2-0.5 mg / L. Diversion zone 6 and sedimentation zone 7 do not require stirring. The sewage undergoes preliminary sedimentation in sedimentation zone 6, and the supernatant of the sewage enters MBR membrane tank 4 through triangular weir plate 13. The supernatant entering MBR membrane tank 4 will still contain a small amount of sludge. After being filtered by the membrane fibers of membrane module 5, it meets the effluent standard. Because the sludge content in the sewage entering MBR membrane tank 4 is greatly reduced, it is not easy to deposit on the surface of the membrane fibers, thereby greatly reducing the rate of membrane fouling in membrane module 5 and extending the service life of the membrane.

[0075] Example 2

[0076] Because existing wastewater treatment processes add phosphorus removal agents before they are added to the biological treatment tank, this may have a certain impact on microbial activity. This embodiment, based on Example 1, aims to improve phosphorus removal efficiency by, for example... Figure 1 As shown, in this embodiment, a first dosing pipe 19 is provided on the side of the sedimentation zone 7 near the flow guide zone 6, and a second dosing pipe 20 is provided in the MBR membrane tank 4; the first dosing pipe 19 and the second dosing pipe 20 can be used to add phosphorus removal agent to the sedimentation zone 7 and the MBR membrane tank 4, either alone or simultaneously.

[0077] Furthermore, the amount of phosphorus removal agent that needs to be added to the sedimentation tank is calculated using the following formula:

[0078] When iron salts are used as phosphorus removal agents:

[0079] m = 2.7 × (C0 - C) × Q

[0080] When aluminum salts are used as dephosphorizing agents:

[0081] m = 1.3 × (C0 - C) × Q

[0082] In the formula, m is the mass of the reagent; C0 is the total phosphorus concentration in the influent, C is the total phosphorus concentration in the effluent, and Q is the water volume.

[0083] The phosphorus removal agent is added directly to the beginning of sedimentation zone 7 without affecting biological activity. Furthermore, during the sludge discharge process in sedimentation zone 7, most phosphorus-containing pollutants have already been discharged. Further filtration by the membrane fibers in membrane module 5 allows for even better phosphorus removal, achieving highly efficient phosphorus removal. Through multi-point dosing and pre-discharge of sludge, combined with the microfiltration performance of the membrane module 5 itself, particulate total phosphorus in the water is significantly removed, improving phosphorus removal efficiency.

[0084] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-flux, high-efficiency phosphorus removal MBR process, wherein the MBR process includes: utilizing an anaerobic zone for organic matter degradation, nitrogen removal, and sulfide degradation of wastewater to achieve preliminary purification and biological waterproofing; utilizing an anoxic zone for secondary organic matter degradation, secondary nitrogen removal, and sulfur and nitrate reduction of wastewater to achieve filter material regeneration and reasonable control of sludge production; utilizing an aerobic zone for biological oxidation, tertiary nitrogen removal, and abnormal gas removal of wastewater to achieve abnormal gas removal, biological decomposition of COD and BOD in wastewater, and biofilm reconstruction; and utilizing the membrane modules of the MBR membrane tank for final solid-liquid separation and biological treatment of wastewater; characterized in that: This MBR process also includes a flow guide zone and a sedimentation zone between the aerobic zone and the MBR membrane tank; The diversion zone is a pool structure, with a diversion wall between it and the aerobic zone, and a partition wall between it and the sedimentation zone. The diversion wall has diversion holes, and an inlet is opened at the top of the partition wall. A return pump is installed in the pool of the diversion zone. Wastewater in the aerobic zone enters the diversion zone through the diversion holes on the diversion wall, and some wastewater is returned to the inlet of the anoxic zone by the return pump. After being buffered by the diversion zone, the wastewater enters the sedimentation zone through the inlet at the top of the partition wall. The sedimentation zone is also a tank structure, and several triangular weir plates are provided between it and the MBR membrane tank. The bottom of the sedimentation zone is equipped with a sludge discharge pipe and a sludge discharge pump installed on the sludge discharge pipe. Wastewater is removed by sedimentation in the sedimentation zone, and the supernatant of the wastewater in the sedimentation zone enters the MBR membrane tank through the triangular weir plates. The flow rate of the diversion zone is calculated using the following formula: Water flow rate in the diversion zone In the formula, q is the influent flow rate; R is the reflux ratio; The number of guide holes on the guide wall and the diameter of the guide holes are determined by calculating the water flow rate. The flow rate between the sedimentation tank and the MBR membrane tank is equal to the hourly inflow rate of the two return pumps when they are turned on simultaneously, which is the maximum design flow rate. The triangular weir plate of the sedimentation zone is calculated using the following formula: ； The outlet weir adopts a 90-degree triangular weir, with N weir openings per meter of weir plate; ； ； ； ； The free fall height of the water outlet tank is ; ； The sedimentation zone is equipped with a first dosing pipe on the side of the flow guide zone, and the MBR membrane tank is equipped with a second dosing pipe; phosphorus removal agent can be added to the sedimentation zone and the MBR membrane tank individually or simultaneously through the first and second dosing pipes.

2. The MBR process with high membrane flux and efficient phosphorus removal according to claim 1, characterized in that: The volume of the flow guidance zone is calculated using the following formula: Diversion zone pool volume In the formula, T is the sedimentation time; q is the influent flow rate; L is the total length of the tank; H is the depth of the tank; and B is the width of the tank.

3. The MBR process with high membrane flux and efficient phosphorus removal according to claim 1, characterized in that: The volume of the sedimentation zone is calculated using the following formula: Sedimentation tank volume In the formula, T is the sedimentation time; q is the influent flow rate q (m³). 3 / h).

4. The MBR process with high membrane flux and efficient phosphorus removal according to claim 1, characterized in that: The amount of phosphorus removal agent to be added to the sedimentation tank is calculated using the following formula: When iron salts are used as phosphorus removal agents: When aluminum salts are used as dephosphorizing agents: In the formula, m is the mass of the drug; C is the total phosphorus concentration in the influent, Q is the total phosphorus concentration in the effluent, and Q is the water volume.

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