High-ammonia-nitrogen wastewater treatment device based on zeolite and MBR combined process

Abstract

The utility model discloses a high-ammonia-nitrogen wastewater treatment device based on a zeolite and MBR combined process. The high-ammonia-nitrogen wastewater treatment device comprises an adjusting tank, a biochemical reaction tank, an MBR membrane tank, a reflux tank and a water producing tank, the interior of the biochemical reaction tank is divided into an anoxic zone and an aerobic zone by a first partition plate, a submersible stirrer is arranged in the anoxic zone, an aeration device is arranged in the aerobic zone, zeolite particles are filled in the anoxic zone, a grid mesh for intercepting the zeolite particles is arranged at an overflow port of the aerobic zone, and an MBR membrane assembly is arranged in the MBR membrane tank; the regulating tank is connected with the biochemical reaction tank through a lifting pump and a lifting pipeline, the anoxic zone, the aerobic zone, the MBR membrane tank and the reflux tank are in overflow connection in sequence, the reflux tank is connected with the anoxic zone through a reflux pump and an external reflux pipeline, and the MBR membrane assembly is connected with the water producing tank through a water producing pump and a water producing pipe. The device can improve the treatment efficiency and treatment effect of the ammonia-nitrogen wastewater and improve the effluent quality.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment technology, specifically to a high ammonia nitrogen wastewater treatment device based on a zeolite and MBR combined process. Background Technology

[0002] Direct discharge of high-concentration ammonia nitrogen wastewater poses a significant hazard, but its treatment is difficult and costly. Currently, widely used treatment methods include breakpoint chlorination, air stripping, chemical precipitation, biological methods, and adsorption. Breakpoint chlorination and chemical precipitation require the addition of chemicals to the wastewater, resulting in secondary environmental pollution and poor economic efficiency. Biological and adsorption methods are favored for their environmental friendliness, low cost, and ease of operation in the treatment of ammonia nitrogen wastewater. However, biological methods suffer from unsatisfactory treatment effects and require large land areas, while adsorption methods are hampered by rapid adsorbent saturation leading to a decrease in treatment capacity. Utility Model Content

[0003] To address the aforementioned problems, this invention provides a high ammonia nitrogen wastewater treatment device based on a zeolite and MBR combined process.

[0004] The technical solution adopted in this utility model is:

[0005] A high-ammonia nitrogen wastewater treatment device based on a zeolite and MBR combined process includes a biological reaction tank, an MBR membrane tank, a reflux tank, and a product water tank. The biological reaction tank is divided into an anoxic zone and an aerobic zone by a first baffle. The anoxic zone is equipped with a submersible agitator and zeolite particles, which are fluidized under the action of the agitator. The aerobic zone is equipped with an aeration device, and a screen for intercepting zeolite particles is installed at the overflow outlet of the aerobic zone. The MBR membrane tank is equipped with an MBR membrane module. The anoxic zone, aerobic zone, MBR membrane tank, and reflux tank are sequentially overflowed and connected. The reflux tank is connected to the anoxic zone through a reflux pump and an external reflux pipe. The MBR membrane module is connected to the product water tank through a product water pump and a product water pipe.

[0006] Furthermore, it also includes an equalization tank and a bar screen. The equalization tank is connected to the biochemical reaction tank via a booster pump and a booster pipe, and a bar screen is installed on the inlet side of the equalization tank.

[0007] The equalization tank is used to regulate water volume and quality, while the bar screen is used to intercept larger particulate impurities, reduce the load on subsequent treatment units, and protect subsequent treatment equipment.

[0008] Furthermore, it also includes a hydrocyclone separator and a chemical regeneration tank. The inlet of the hydrocyclone separator is connected to the biological tank and the MBR membrane tank through a first sludge pump and a second sludge pump, respectively. The top outlet of the hydrocyclone separator is connected to the MBR membrane tank and the biological tank through a third sludge pump and a fourth sludge pump, respectively. The bottom outlet of the hydrocyclone separator is connected to the biological tank and the chemical regeneration tank through pipelines, respectively. The zeolite in the chemical regeneration tank is chemically regenerated and then returned to the biological tank.

[0009] To prevent small amounts of zeolite entering the MBR membrane tank through the screen from adversely affecting the membrane modules, hydrocyclones are installed on the sludge discharge lines of the biological treatment tank and the MBR membrane tank to separate the sludge from the zeolite. During normal system operation, the valves on the MBR membrane tank sludge discharge line and the second sludge pump are opened, while the valves on the biological treatment tank sludge discharge line and the first sludge pump are closed. The sludge in the MBR membrane tank enters the hydrocyclone for separation. The separated sludge is returned to the MBR membrane tank via a third sludge pump, while the separated zeolite enters the chemical regeneration tank. When chemical regeneration of the zeolite adsorbent is required, the valves on the MBR membrane tank sludge discharge line and the second sludge pump are closed, while the valves on the biological treatment tank sludge discharge line and the first sludge pump are opened. The sludge in the biological treatment tank enters the hydrocyclone for separation. The separated sludge is returned to the biological treatment tank via a fourth sludge pump, while the separated zeolite enters the chemical regeneration tank. After regeneration, the zeolite returns to the anoxic zone of the biological treatment tank.

[0010] Furthermore, it also includes a first dosing system, which includes an acid storage tank and an acid pump. The acid storage tank is connected to the permeate outlet of the membrane module, the MBR membrane tank, and the chemical regeneration tank via the acid pump and pipelines.

[0011] The first dosing system enables online or offline acid washing of the membrane modules to ensure their filtration performance. After a period of use, the zeolite particles will reach saturation. The first dosing system is used to periodically chemically regenerate them with acid to remove adsorbates from the adsorbent surface and restore their adsorption capacity.

[0012] Furthermore, the aerobic zone is equipped with a mixed liquor reflux pump, and the aerobic zone is connected to the anoxic zone through the mixed liquor reflux pump and the internal reflux pipe.

[0013] After the zeolite undergoes biological regeneration in the aerobic zone, a portion is returned to the anoxic zone via a mixed liquor reflux pump to re-adsorb ammonia nitrogen. Controlling the reflux ratio to 300–500% ensures the reflux effect. To ensure the residence time in the biochemical reaction tank, intermittent internal reflux is preferred. To ensure the adsorption-desorption balance, the pH value in the biochemical tank is preferably 6.5–8.5.

[0014] Furthermore, the aerobic zone is divided into a first aerobic zone and a second aerobic zone by a second partition, and the first aerobic zone and the second aerobic zone are connected through the bottom of the second partition.

[0015] It increases the residence time of wastewater in the aerobic zone and makes it easier to control the overflow of the aerobic zone effluent through the screen into the MBR membrane tank.

[0016] Furthermore, aerators are installed at the bottom of the aerobic zone and on the side walls of the second aerobic zone. A membrane scrubbing aeration device is installed at the bottom of the MBR membrane module. The membrane scrubbing aeration device and the aerators share a set of air supply devices.

[0017] Reduce equipment investment and improve the utilization rate of the aeration unit. Aerators are installed at the bottom of the aerobic zone and on the effluent side to ensure the dissolved oxygen concentration in the aerobic zone and prevent zeolite from accumulating in front of the screen, further preventing zeolite from entering the MBR membrane tank. To reduce the erosion of the biofilm on the zeolite surface and maintain microbial activity, microporous aeration is preferred.

[0018] Furthermore, the permeate tank is connected to the permeate outlet of the membrane module via a backwash pump and backwash pipe.

[0019] After a period of operation, the MBR membrane tank needs to be backwashed. The membrane modules are backwashed using the permeate tank, eliminating the need for an additional backwash tank and reducing equipment investment and installation space.

[0020] Furthermore, it also includes a second dosing system, which includes an alkali storage tank and an alkali pump. The alkali storage tank is connected to the product water outlet of the membrane module through the alkali pump and pipeline.

[0021] The membrane module can be subjected to online or offline alkaline washing through a second dosing system to ensure its filtration performance.

[0022] Furthermore, the MBR membrane tank and the aerobic zone share a single aeration system. This reduces equipment investment and improves the utilization rate of the aeration system. Aerators are installed at the bottom and on the effluent side of the aerobic zone to ensure the dissolved oxygen concentration in the aerobic zone and prevent zeolite from accumulating in front of the screen, further preventing zeolite from entering the MBR membrane tank. To reduce the erosion of the biofilm on the zeolite surface and maintain microbial activity, a microporous aeration method is preferred.

[0023] Furthermore, the zeolite particles are either artificial or natural zeolite, with a particle size of 2–3 mm. They exhibit good adsorption properties and are not easily broken. The 2–3 mm zeolite particle size can optimize hydraulic conditions and reduce clogging of the grid mesh.

[0024] The beneficial effects of this utility model are:

[0025] 1. This device uses a combination of zeolite and MBR technology to treat high ammonia nitrogen wastewater. The zeolite crystal structure contains numerous ion exchange sites that can be occupied by cations such as ammonia nitrogen. Its rich microporous and mesoporous structure provides a large surface area and pore volume. By adding zeolite particles to activated sludge, the particles are fluidized under the action of a stirrer, serving as a carrier for microorganisms. A biofilm can stably grow on its surface, increasing biomass, reducing turbidity, and shortening hydraulic retention time. By combining biological and adsorption methods, the effluent quality meets the Class A standard of the first-class urban wastewater discharge standard (GB18918-2002), and can be used for reclaimed water reuse.

[0026] 2. The addition of zeolite can effectively reduce the load on the MBR membrane, which helps to slow down MBR membrane fouling and improve membrane lifespan. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the high ammonia nitrogen wastewater treatment device of this application. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solution of this utility model will be clearly and completely described below in conjunction with the accompanying drawings and a preferred embodiment.

[0029] See Figure 1 A high-ammonia nitrogen wastewater treatment device based on a zeolite and MBR combined process includes a bar screen 1, an equalization tank 2, a biochemical reaction tank 3, an MBR membrane tank 4, a reflux tank 5, a product water tank 6, a hydrocyclone separator 9, a chemical regeneration tank 10, and a dosing system. The bar screen 1, equalization tank 2, and biochemical reaction tank 3 are connected sequentially by pipelines. The biochemical reaction tank 3, MBR membrane tank 4, and reflux tank 5 are connected by an overflow. The product water tank 6 is connected to the MBR membrane tank 4 by a pipeline. The inlet of the hydrocyclone separator 9 is connected to the biochemical tank 3 and the MBR membrane tank 4 by a first sludge pump 9a and a second sludge pump 9b, respectively. The top outlet of the hydrocyclone separator 9 is connected to the MBR membrane tank 4 and the biochemical tank 3 by a third sludge pump 9c and a fourth sludge pump 9h, respectively. The bottom outlet of the hydrocyclone separator 9 is connected to the biochemical tank 3 and the chemical regeneration tank 10 by pipelines, respectively. The dosing system is connected to the biochemical reaction tank 3, the MBR membrane tank 4, and the chemical regeneration tank 10 by pipelines.

[0030] In practice, the bar screen 1 is equipped with a bar screen to intercept larger particulate impurities, reduce the load on subsequent treatment units, and protect subsequent treatment equipment; the equalization tank 2 is used to regulate the quality and quantity of wastewater to prevent drastic changes in the biological treatment system. The equalization tank 2 is connected to the bar screen 1 by a pipeline. High ammonia nitrogen wastewater entering the bar screen 1 flows by gravity to the equalization tank 2 after being filtered by the bar screen.

[0031] The biochemical reactor 3 is divided into two zones by a partition 3c: an anoxic zone 3a and an aerobic zone 3b. The anoxic zone contains activated sludge and zeolite particles 3e. A submersible mixer 3g is installed at the bottom of the anoxic zone to mix the activated sludge and zeolite particles; the submersible mixer is equipped with a protective cover to prevent wear from the zeolite. The aerobic zone 3b is divided into a first aerobic zone and a second aerobic zone by a non-bottom-touching partition 3d, which are connected by the space at the bottom of the partition. The first aerobic zone overflows into the anoxic zone 3a. The aerobic zone 3b is equipped with an aeration device for oxygenation and mixing. An overflow outlet is located at the top of the second aerobic zone, and a stainless steel mesh 3i is installed at the overflow outlet to intercept zeolite particles; preferably, the mesh spacing of the stainless steel mesh 3i is 1mm; the diameter of the zeolite particles is 2-3mm. The second aerobic zone overflows directly into the MBR membrane tank 4.

[0032] The equalization tank 2 and the biological reaction tank 3 are connected by a pipeline and a booster pump 2a. The high ammonia nitrogen wastewater in the equalization tank 2 is boosted to the anoxic zone 3a by the booster pump 2a. In the anoxic zone 3a, heterotrophic bacteria metabolize pollutants such as proteins and fats into NH3-N through ammonification. Zeolite 3e adsorbs the metabolite NH3-N, thereby realizing the adsorption and denitrification functions of the high nitrogen wastewater. Then, it overflows into the aerobic zone 3b. In the aerobic zone 3b, autotrophic bacteria oxidize the ammonia nitrogen in the wastewater, including the ammonia nitrogen adsorbed on the zeolite, into nitrate nitrogen through nitrification, further removing organic matter and ammonia nitrogen from the wastewater, while also enabling the zeolite to undergo biological regeneration.

[0033] The optimal residence time for high-ammonia nitrogen wastewater in the biochemical reaction tank is 0.5–2 hours in the anoxic zone 3a and 2–4 hours in the aerobic zone 3b. This ensures the treatment efficiency and effectiveness of the ammonia nitrogen wastewater.

[0034] Ideally, a mixed liquor reflux pump 3f is installed in the aerobic zone 3b, which is connected to the anoxic zone 3a via the mixed liquor reflux pump 3f and an internal reflux pipe. After biological regeneration in the aerobic zone, a portion of the zeolite is refluxed back to the anoxic zone via the mixed liquor reflux pump for renewed ammonia nitrogen adsorption. The preferred reflux ratio is 300%–500%. To ensure sufficient residence time in the biological treatment tank, the reflux method is further preferred to be intermittent. For example, a valve 3j can be installed on the inlet pipe of the mixed liquor reflux pump 3f, which is opened every 3 hours for 30 minutes of reflux.

[0035] Aerators 3k are installed at the bottom and outlet side of the preferred aerobic zone 3b. Aerators 3k are connected to the air supply device 3h through pipes to ensure the dissolved oxygen concentration in the tank while preventing the accumulation of zeolite in front of the screen, and further ensuring that the zeolite is intercepted in the biological tank.

[0036] The connection method between the bottom outlet of the hydrocyclone separator 9 and the biological treatment tank 3 and the chemical regeneration tank 10 is not limited, as long as the zeolite particles separated by the hydrocyclone separator 9 can enter the biological treatment tank 3 and the chemical regeneration tank respectively. The connection method between the biological treatment tank 3 and the chemical regeneration tank 10 is also not limited, as long as the regenerated zeolite can enter the chemical regeneration tank 10. In this embodiment, the bottom outlet of the hydrocyclone separator 9 is connected to the chemical regeneration tank 10 through a pipe and valves 9f and 10b installed on the pipe. The pipe between valves 9f and 10b is connected to the biological treatment tank 3 through a tee pipe, valve 10c, and sludge pump 10a.

[0037] In this embodiment, during normal system operation, the valve on the sludge discharge pipe of the MBR membrane tank and the second sludge pump 9b are opened, the valve 9d on the sludge discharge pipe of the biological treatment tank and the first sludge pump 9a are closed, the valve 9e on the sludge inlet pipe of the MBR membrane tank and the third sludge pump 9c are opened, the valve 9g on the sludge inlet pipe of the biological treatment tank and the fourth sludge pump 9h are closed, the valve 9f and valve 10b on the bottom outlet pipe of the hydrocyclone separator are opened, and the valve 10c and sludge pump 10a are closed. The sludge in the MBR membrane tank 4 enters the hydrocyclone separator 9 for separation, the separated sludge is returned to the MBR membrane tank via the third sludge pump 9c, and the separated zeolite enters the chemical regeneration tank 10.

[0038] When the zeolite adsorbent needs to be chemically regenerated, close the valve on the sludge discharge pipe of the MBR membrane tank and the second sludge pump 9b, open the valve 9d on the sludge discharge pipe of the biological treatment tank and the first sludge pump 9a, close the valve 9e on the sludge inlet pipe of the MBR membrane tank and the third sludge pump 9c, open the valve 9g on the sludge inlet pipe of the biological treatment tank and the fourth sludge pump 9h, open the valve 9f and valve 10b on the bottom outlet pipe of the hydrocyclone separator, and close the valve 10c and sludge pump 10a; the sludge in the biological treatment tank enters the hydrocyclone separator for separation, and the separated sludge is returned to the biological treatment tank via the fourth sludge pump, while the separated zeolite enters the chemical regeneration tank 10.

[0039] After regeneration is complete, valve 9f is closed and sludge pump 10a is started, and the zeolite in the chemical regeneration tank is returned to the biological tank.

[0040] The MBR membrane tank 4 is equipped with a membrane module 4a and a permeate pump 4b. The membrane module 4a has a permeate outlet 4c and an aeration outlet 4d. The permeate outlet 4c is connected to the permeate tank 6 through a production pipe and the permeate pump 4b. The aeration outlet 4d is connected to the air supply device 3h through a pipe. In this embodiment, the membrane module and the aerobic zone use the same air supply device 3h.

[0041] The MBR membrane tank 4 is directly overflowed into the aerobic zone 3b. The high-nitrogen wastewater undergoes adsorption-denitrification-nitrification reaction in the high-nitrogen wastewater regeneration reaction tank 3. After being filtered by the stainless steel grid 3i, the wastewater enters the MBR membrane tank 4. The permeate from the membrane module 4a is pumped into the permeate tank 6 by the permeate pump 4b. The permeate can meet the Class A standard of the first-class urban sewage discharge standard (GB18918-2002).

[0042] After the membrane module 4a has been running for a period of time, it needs to be backwashed. Therefore, in this embodiment, a backwash pump 6a and a backwash pipe are also provided. The product water tank 6 is connected to the product water port of the membrane module 4a through the backwash pump 6a and the backwash pipe.

[0043] During normal operation, the membrane surface of membrane module 4a will become fouled by particulate matter, such as microorganisms, salt deposits, and non-dissolved organic matter (such as petroleum hydrocarbons), thus requiring routine maintenance. This can be controlled through online cleaning during routine operation to reduce contaminant deposition on the membrane surface. When high-flux backwashing, air scrubbing, and online cleaning are insufficient to maintain adequate membrane permeate performance, causing the transmembrane pressure differential to approach the upper limit of operating requirements, offline cleaning of the membrane module is necessary.

[0044] Furthermore, zeolite adsorbents will reach saturation after a period of use, and the adsorbent needs to be chemically regenerated periodically to remove the adsorbate on the surface of the adsorbent and restore its adsorption capacity.

[0045] Therefore, this application also includes a dosing system and a chemical regeneration system. The dosing system includes a first dosing system and a second dosing system. The first dosing system includes an acid storage tank 7, an acid dosing pipeline, and an acid dosing pump 7a. The acid storage tank 7 is connected to the permeate outlet of the membrane module 4a through the acid dosing pump 7a, a first valve, and a first acid dosing pipeline. It is also connected to the MBR membrane tank 4 through the acid dosing pump 7a, a second valve, and a second acid dosing pipeline. Furthermore, it is connected to the chemical regeneration tank 10 through the acid dosing pump 7a, a third valve, and a third acid dosing pipeline.

[0046] Online and offline cleaning of membrane module 4a and chemical regeneration of zeolite are existing technologies, and the specific methods will not be described in detail here.

[0047] The chemical regeneration method for zeolite adsorbent is as follows: Acid solution is pumped into chemical regeneration tank 10 via acid pump 7a. After regeneration, sludge pump 10a is started to pump the zeolite from the chemical regeneration tank into the anoxic zone 3a of the biological treatment tank. After regeneration, the solution is discharged through the drain pipe (not shown in the diagram) at the bottom of chemical regeneration tank 10. The regeneration frequency is controlled at 20–25 days / time, and the regeneration time is controlled at 90–120 minutes.

[0048] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model, and these improvements and modifications are also within the protection scope of the present utility model.

Claims

1. A high-ammonia nitrogen wastewater treatment device based on a zeolite and MBR combined process, characterized in that, It includes a biochemical reactor (3), an MBR membrane tank (4), a return tank (5), and a product water tank (6). The biochemical reactor (3) is divided into an anoxic zone (3a) and an aerobic zone (3b) by a first partition (3c). The anoxic zone (3a) is equipped with a submersible agitator (3g) and zeolite particles (3e). The zeolite particles (3e) are fluidized under the action of the agitator. The aerobic zone (3b) is equipped with an aeration device (3h). The aerobic zone (3b) overflows. The inlet is equipped with a grid (3i) for intercepting zeolite particles (3e). The MBR membrane tank (4) is equipped with an MBR membrane module (4a). The anoxic zone (3a), aerobic zone (3b), MBR membrane tank (4), and reflux tank (5) are connected in sequence by overflow. The reflux tank (5) is connected to the anoxic zone (3a) through a reflux pump (5a) and an external reflux pipe. The MBR membrane module (4a) is connected to the permeate tank (6) through a permeate pump (4b) and a permeate pipe.

2. The high ammonia nitrogen wastewater treatment device based on a zeolite and MBR combined process according to claim 1, characterized in that, It also includes a regulating tank (2), which is connected to the biochemical reaction tank (3) via a booster pump (2a) and a booster pipe. A screen tank (1) is installed on the inlet side of the regulating tank (2).

3. The high ammonia nitrogen wastewater treatment device based on a zeolite and MBR combined process according to claim 1, characterized in that, It also includes a hydrocyclone separator (9) and a chemical regeneration tank (10). The inlet of the hydrocyclone separator (9) is connected to the biochemical reaction tank (3) and the MBR membrane tank (4) through the first sludge pump (9a) and the second sludge pump (9b), respectively. The top outlet of the hydrocyclone separator (9) is connected to the MBR membrane tank (4) and the biochemical reaction tank (3) through the third sludge pump (9c) and the fourth sludge pump (9h), respectively. The bottom outlet of the hydrocyclone separator (9) is connected to the biochemical reaction tank (3) and the chemical regeneration tank (10) through pipelines, respectively. The zeolite in the chemical regeneration tank (10) is chemically regenerated and then returned to the biochemical reaction tank (3).

4. A high-ammonia nitrogen wastewater treatment device based on a zeolite and MBR combined process according to claim 1 or 3, characterized in that, It also includes a first dosing system, which includes an acid storage tank (7) and an acid pump (7a). The acid storage tank (7) is connected to the permeate outlet of the membrane module (4a), the MBR membrane tank (4) and the chemical regeneration tank (10) through the acid pump (7a) and pipelines.

5. A high-ammonia nitrogen wastewater treatment device based on a zeolite and MBR combined process according to claim 1, characterized in that, The aerobic zone (3b) is equipped with a mixed liquor reflux pump (3f), and the aerobic zone (3b) is connected to the anoxic zone (3a) through the mixed liquor reflux pump (3f) and the internal reflux pipe.

6. The high ammonia nitrogen wastewater treatment device based on a zeolite and MBR combined process according to claim 1, characterized in that, The aerobic zone (3b) is divided into a first aerobic zone and a second aerobic zone by a partition (3d), and the first aerobic zone and the second aerobic zone are connected through the bottom of the partition (3d).

7. A high-ammonia nitrogen wastewater treatment device based on a zeolite and MBR combined process according to claim 6, characterized in that, Aerators (3k) are installed at the bottom of the aerobic zone (3b) and on the side wall of the second aerobic zone. A membrane scrubbing aeration device is installed at the bottom of the MBR membrane module (4a). The membrane scrubbing aeration device and the aerator (3k) share a set of aeration devices (3h).

8. A high-ammonia nitrogen wastewater treatment device based on a zeolite and MBR combined process according to claim 1, characterized in that, The permeate tank (6) is connected to the permeate outlet of the membrane module (4a) via a backwash pump (6a) and a backwash pipe.

9. A high-ammonia nitrogen wastewater treatment device based on a zeolite and MBR combined process according to claim 1, characterized in that, It also includes a second dosing system, which includes an alkali storage tank (8) and an alkali pump (8a). The alkali storage tank (8) is connected to the product water outlet of the membrane module (4a) via the alkali pump (8a) and a pipeline.

10. A high-ammonia nitrogen wastewater treatment device based on a zeolite and MBR combined process according to claim 1, characterized in that, Zeolite particles (3e) are artificial or natural zeolite with a particle size of 2-3 mm.

Images