Tubular dynamic membrane sulfur autotrophic denitrification device and method

Abstract

The invention discloses a tubular dynamic membrane sulfur autotrophic denitrification device and method, the device comprises: a housing, which is composed of a middle cylindrical structure and two end hemispherical structures, the upper part of the cylindrical structure is provided with a purified water outlet, the lower part is provided with a backwashing port, and the top end of the hemispherical structure is respectively provided with a sewage inlet and a concentrated liquid outlet; the plurality of supporting bodies are arranged in parallel, each supporting body is composed of two layers of honeycomb-shaped PVC grids and a layer of polypropylene net, and the polypropylene net is clamped between the two layers of honeycomb-shaped PVC grids; the two splitter plates are fixed to the two ends of the supporting body respectively, and splitter holes corresponding to the supporting body are formed in the splitter plates; a large-aperture polypropylene net is used as a filtering support body, and powdered sulfur is used as a precoating agent, so that the problems of difficulty in powdered sulfur recovery and serious loss in the traditional sulfur autotrophic process are solved; meanwhile, sulfur powder with a certain particle size is used as a dynamic membrane reactor of a precoating agent, nitrate nitrogen can be efficiently removed, the effluent quality is improved, and meanwhile the dynamic membrane reactor has the advantages of being resistant to pollution and easy to clean.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a tubular dynamic membrane sulfur autotrophic denitrification device and method. Background Art

[0002] Sulfur autotrophic denitrification technology is a novel, carbon-independent denitrification technology. Its electron donors are inexpensive and readily available sulfides and elemental sulfur. The sulfur autotrophic denitrification reaction is an interfacial biological reaction, and its reaction rate is positively correlated with the specific surface area of ​​the filler. Commercially available sulfur autotrophic fillers are mostly in the form of filter media, which have relatively small specific surface areas, slow reaction rates, and the disadvantages of filler fragmentation and compaction. Direct addition of sulfur powder to the water tank also suffers from sulfur loss and low sulfur utilization.

[0003] Traditional membrane bioreactors mostly use small-pore membranes such as microfiltration or ultrafiltration. Although the effluent quality is better, the membranes are easily clogged and difficult to clean. Dynamic membranes, also known as secondary membranes, use large-pore filter materials such as nylon mesh as a support. Pre-coating agents are used to bridge the support so that the particles are retained and gradually thicken, forming a filter cake layer, which is also called a filter membrane. As the thickness of the filter membrane increases, the membrane flux decreases to a certain level, and then backwashing can be performed to cause the membrane layer to fall off and the membrane flux to recover. Existing dynamic membranes have the following problems during use: 1. The traditional dynamic membrane support is not strong enough and is easily deformed during filtration, resulting in uneven film formation; 2. The pre-coating agent is only used to intercept particulate matter and is not combined with the biological reaction; 3. The membrane pores are easily clogged by mycelium, resulting in poor filtration effect. Summary of the Invention

[0004] In response to the problems existing in the prior art, the present invention provides a tubular dynamic membrane sulfur autotrophic denitrification device and method, which uses a large-pore polypropylene mesh as a filter support and sulfur powder as a pre-coating agent to solve the problem of difficult sulfur powder recovery and serious loss in traditional sulfur autotrophic processes; at the same time, the dynamic membrane reactor using sulfur powder of a certain particle size as a pre-coating agent can efficiently remove nitrate nitrogen, improve the water quality of the effluent, and has the advantages of anti-pollution and easy cleaning.

[0005] The technical solutions of the present invention are as follows: In a first aspect of the present invention, a tubular dynamic membrane sulfur autotrophic denitrification device is provided, comprising: The outer shell consists of a cylindrical structure in the middle and hemispherical structures at both ends. The upper part of the cylindrical structure is provided with a clean water outlet, the lower part is provided with a backwash port, and the top of the hemispherical structure is provided with a sewage inlet and a concentrated liquid outlet. A plurality of support bodies arranged in parallel, each support body comprising two layers of honeycomb PVC grids and a layer of polypropylene mesh, wherein the polypropylene mesh is sandwiched between the two layers of honeycomb PVC grids; Two diverter plates are fixed to both ends of the support body, and the diverter plates are provided with diverter holes corresponding to the support body; The inner cavity of the support body forms a filter chamber, the two diverter plates and the outer shell respectively form an inlet filter chamber and an outlet filter chamber, and a filter chamber is formed between the support body and the outer shell; sulfur powder dissolves in water to form a suspension, which enters the filter chamber and gradually forms a dynamic filter membrane on the polypropylene net. Sewage enters the filter chamber for sulfur autotrophic denitrification reaction. In some embodiments of the present invention, the pore size of the polypropylene mesh is 100-150 μm, and the particle size of the sulfur powder is larger than the pore size of the polypropylene mesh.

[0006] In some embodiments of the present invention, the particle size of the sulfur powder is 150-200 μm.

[0007] In some embodiments of the present invention, the backwash port is arranged near a sewage inlet, and the clean water outlet is arranged near a concentrate outlet. In some embodiments of the present invention, the sewage inlet is connected to a sewage pool, the clean water outlet is connected to a clean water pool, and the tubular dynamic membrane sulfur autotrophic denitrification device operates in a manner of multiple membrane tubes connected in series.

[0008] In some embodiments of the present invention, the concentration of the sulfur powder dissolved in water to form a suspension is 40-60 g / L. In some embodiments of the present invention, the honeycomb PVC grid and the polypropylene mesh are both cylindrical.

[0009] In a second aspect of the present invention, a tubular dynamic membrane sulfur autotrophic denitrification method is provided, comprising the following steps: Sulfur powder is added to the sewage pool to form a suspension, which is pumped into the filter chamber through the water inlet pump to form a sulfur powder pre-coating on the surface of the polypropylene mesh; Nitrate-containing wastewater is introduced in a cross-flow filtration mode, so that sludge microorganisms are attached to the pre-coating layer, and sulfur powder acts as an electron donor for denitrification. In some embodiments of the present invention, nitrogen generated during the denitrification reaction flushes the filter cake layer to maintain the membrane flux; when the membrane flux drops to 1000 L / (m²·h), it is backwashed with clean water from the clean water tank, and the fallen filter cake is returned to the sewage tank for recycling.

[0010] In some embodiments of the present invention, the dosage of the sulfur powder is 40-60 g / L, preferably, the dosage is 50 g / L.

[0011] One or more technical solutions of the present invention have the following beneficial effects: (1) The pipe type dynamic membrane sulfur autotrophic denitrification device designed in the application uses sulfur powder as a pre-coating agent, and mixed sludge as a filtrate, the filter cake formed is combined with the extracellular protein generated in the sludge, the inner layer filter cake structure close to the support is fluffy and easy to backwash, the surface filter cake is washed away by the filtrate and is continuously replenished by the sludge, so that the membrane flux is kept in the best state for a long time.

[0012] (2) The pipe type dynamic membrane sulfur autotrophic denitrification device designed in the application can be used as a biological reaction device, the sulfur autotrophic bacteria in the sludge serve as the reaction main body, and the pre-coating agent sulfur powder serves as the electron donor for the reaction, under the action of the sulfur autotrophic bacteria, the nitrate in the sewage is converted into nitrogen, thereby playing a role in denitrification and nitrogen removal.

[0013] (3) The pre-coating agent and the sludge in the pipe type dynamic membrane sulfur autotrophic denitrification device designed in the application jointly form a filter cake, the filter cake performs denitrification reaction while being filtered, the thicker the filter cake, the more intense the reaction, the more nitrogen generated by the denitrification reaction, and the nitrogen can wash away part of the surface filter cake, so that the filter cake becomes thinner, and the filter cake can be kept in a high-flux state for a long time.

[0014] (4) The pipe type dynamic membrane sulfur autotrophic denitrification device designed in the application can be connected in series by multiple roots, and according to the water quality of the sewage, the sludge age and the residence time, any multiple roots can be selected to be connected in series to ensure the denitrification efficiency of the effluent.

[0015] (5) The pipe type dynamic membrane sulfur autotrophic denitrification device designed in the application can efficiently intercept sulfur powder to prevent the loss of sulfur powder, and the device is also designed with a concentrated water pool to collect sulfur powder and sludge and return them to the device for reuse. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a structure schematic view of the pipe type dynamic membrane sulfur autotrophic denitrification device of the application; Figure 2 It is a structure schematic view of a PVC lining membrane support of the application; Figure 3 It is an embodiment schematic view of the pipe type dynamic membrane sulfur autotrophic denitrification device of the application.

[0017] In the figure: 1, outer shell; 2, shunt plate; 3, sewage inlet; 4, water inlet filter chamber; 5, backwashing port; 6, filter cavity; 7, filter chamber; 8, support; 81, polypropylene net; 82, honeycomb-shaped PVC grid; 9, concentrated liquid outlet; 10, water outlet filter chamber; 11, clean water outlet; 01, sewage pool; 02, water inlet pump; 03, pipe type dynamic membrane device; 04, clean water pool. DETAILED DESCRIPTION

[0018] The application will be further described below in combination with the drawings and embodiments.

[0019] Embodiment 1 In a typical embodiment of the present invention, a tubular dynamic membrane sulfur autotrophic denitrification device is proposed, such as Figure 1 Shown, including: The housing 1 is composed of a cylindrical structure in the middle and hemispherical structures at both ends. The upper part of the cylindrical structure is provided with a clean water outlet 11, the lower part is provided with a backwash port 5, and the top of the hemispherical structure is provided with a sewage inlet 3 and a concentrated liquid outlet 9; A plurality of support bodies 8 arranged in parallel, each of the support bodies 8 being composed of two layers of honeycomb PVC grids 82 and a layer of polypropylene mesh 81, wherein the polypropylene mesh 81 is sandwiched between the two layers of honeycomb PVC grids; Two diverter plates 2 are fixed to both ends of the support body 8, and the diverter plates 2 are provided with diverter holes corresponding to the support body; The inner cavity of the support body forms a filter chamber 7, an inlet filter chamber 74 and an outlet filter chamber 107 are respectively formed between the two diverter plates 2 and the outer shell 1, and a filter chamber 6 is formed between the support body and the outer shell 1; sulfur powder dissolves in water to form a suspension, which enters the filter chamber 7, and the sulfur powder gradually forms a dynamic filter membrane on the polypropylene mesh 81, and the sewage enters the filter chamber 7 for sulfur autotrophic denitrification reaction.

[0020] The tubular dynamic membrane sulfur autotrophic denitrification device significantly increases the effective filtration area through the parallel arrangement of multiple supports, making it suitable for high-flow sewage treatment scenarios. A large-pore polypropylene mesh 81 serves as the filter support, and sulfur powder is used as a pre-coating agent to address the difficulty in recovering and severe sulfur powder loss in traditional sulfur autotrophic processes. Using a large-pore polypropylene mesh 81 as the filter support and securing it with a honeycomb PVC grid 82 effectively prevents structural deformation during cross-flow filtration, which can lead to uneven dynamic membrane formation and poor filtration performance. Furthermore, the dynamic filter membrane (sulfur powder pre-coating layer) formed within the support retains sulfur powder through cross-flow filtration. The membrane also performs sulfur autotrophic denitrification. Microorganisms within the sludge use the sulfur powder as an electron donor to convert nitrate into nitrogen gas, thus achieving denitrification.

[0021] In this embodiment, the housing 1 is composed of two hemispherical structures and a cylindrical structure. Two diverter plates 2 are welded to either side of the cylindrical housing 1. The middle portion is the cylindrical housing 1, with an axially symmetrical inlet and outlet at the top and bottom for water intake and clean water discharge during backwashing. The backwash port 5 is located near the sewage inlet 3, and the clean water outlet 11 is located near the concentrate outlet. The two ends of the hemispherical housing 1 are provided with inlets and outlets at the top of each side for sewage intake and filtered concentrate discharge. The membrane housing 1 at both ends and the diverter plates 2 form two chambers, namely the inlet filter chamber 74 and the outlet filter chamber 107. The chamber at the inlet end is the inlet filter chamber 74, which is connected to the sewage inlet 3 and temporarily stores sewage. The chamber at the outlet end is the outlet filter chamber 107, which is connected to the clean water outlet and temporarily stores filtered concentrate. The area between the cylindrical membrane housing 1 and the support body is called the filter chamber 6, which is connected to the clean water outlet and the backwash water inlet. The filter chamber 6 temporarily stores the filtered clear liquid, which can be discharged out of the device through the clean water outlet 11 on the housing 1.

[0022] like Figure 2 As shown, the honeycomb PVC grille and the polypropylene net 81 are both cylindrical, and the area inside the PVC lining membrane support is called the filter chamber 7. The polypropylene net 81 is fixed between two layers of honeycomb PVC grilles 82 to ensure that the polypropylene net 81 will not be displaced by the impact of the water flow. The pre-coating agent forms a filter membrane in the filter chamber 7, and the sewage is separated into solid and liquid by cross-flow filtration. The sludge remains on the filter membrane, and the sewage passes through the filter membrane and the polypropylene net 81 support to reach the filter cavity 6 and finally flows out of the membrane device. There is a filter membrane formed by sulfur powder and sludge on the PVC lining membrane support. The filter membrane also has sulfur autotrophic denitrification. The microorganisms in the sludge use sulfur powder as an electron donor to convert nitrate into nitrogen gas, which plays a role in denitrification.

[0023] Furthermore, the support body is inserted into the vacant space of the diverter plate 2, and after being welded and sealed, the liquid in the support body can only flow in or out through the insertion hole of the diverter plate 2. The area inside the support body becomes the filter chamber 7, and the sewage flows longitudinally in the filter chamber 7, which is also called cross-flow filtration.

[0024] In this embodiment, the water inlet and outlet are not fixed. The device is an axisymmetric structure, and the pipes on each side can serve as the water inlet and outlet. This notation is for ease of description only. The same applies to the inlet filter chamber 74 and the outlet filter chamber 107, as well as the backwash inlet and the clean water outlet 11.

[0025] In this embodiment, the pore size of the polypropylene mesh 81 is 100-150 μm, and the sulfur powder has a larger particle size than the pore size of the polypropylene mesh 81. Furthermore, the sulfur powder has a particle size of 150-200 μm. The specifications of the pre-coat sulfur powder directly affect the performance of the device. In this embodiment, the sulfur powder particle size is preferably 200 μm. When in use, the sulfur powder is first placed in the sewage tank 01. 40-60 g / L of sulfur powder is dissolved in the water to form a suspension of a certain concentration. The suspension is then pumped from the water inlet to the PVC-lined membrane support filter chamber 7 via the water inlet pump 02. The sulfur powder gradually forms a filter membrane on the polypropylene mesh 81, which acts as a filter and provides electrons for denitrification. Multiple experiments have confirmed that sulfur powder with a particle size of 200 μm achieves optimal results, achieving optimal membrane flux and effluent turbidity.

[0026] Furthermore, after the filter membrane is formed, the tubular dynamic membrane sulfur autotrophic denitrification device adopts a cross-flow filtration method to pump the sewage and sludge from the sewage pool 01 into the device through the water inlet pump 02. The microorganisms in the sludge adhere to the filter membrane, using sulfur powder as an electron donor for denitrification, converting the nitrate in the sewage into nitrogen gas, thereby playing a role in denitrification. The microorganisms and extracellular proteins in the sludge can be blocked and adsorbed by the filter membrane and become part of the filter membrane, but an overly thick filter membrane will affect the membrane flux. At thicker filter membranes, due to the abundance of microorganisms and sulfur powder, the sulfur autotrophic reaction is more intense, producing more nitrogen gas. During the release of nitrogen gas, part of the thicker filter membrane can be destroyed, making the filter membrane thinner, and the membrane flux is thus restored.

[0027] like Figure 3 As shown, the tubular dynamic membrane sulfur autotrophic denitrification device is preceded by a sewage tank 01, which serves as a dissolution tank for the precoat agent and a reservoir for the sewage concentrate. A clean water tank 04 is connected to the device, serving as a reservoir for the filtered clear liquid and also as a reservoir for backwash water. The tubular dynamic membrane sulfur autotrophic denitrification device operates using multiple membrane tubes connected in series. Sewage is first pumped from sewage tank 01 into the device. After being filtered through the multiple membrane tubes using cross-flow filtration, the concentrate is finally collected in sewage tank 01, and the filtered clear liquid enters clean water tank 04.

[0028] In this embodiment, the tubular dynamic membrane sulfur autotrophic denitrification device can be backwashed after the membrane flux decreases to 1000 L / (m²·h). This backwash uses clear liquid from the clean water tank 04, which is pumped to the device's backwash port 5. The water flow destroys the sulfur powder pre-coating on the support, gradually removing the filter membrane. The concentrated liquid after backwash, containing denitrifying microorganisms and unused sulfur powder, enters the wastewater tank 01 for reuse.

[0029] Example 2 A typical embodiment of the present invention provides a tubular dynamic membrane sulfur autotrophic denitrification method, comprising the following steps: Sulfur powder is added to the sewage pool to form a suspension, which is pumped into the filter chamber 7 through the water inlet pump to form a sulfur powder pre-coating on the surface of the polypropylene mesh 81; Nitrate-containing wastewater is introduced in a cross-flow filtration mode, so that sludge microorganisms are attached to the pre-coating layer, and sulfur powder acts as an electron donor for denitrification.

[0030] Furthermore, the nitrogen generated during the denitrification reaction flushes the filter cake layer to maintain the membrane flux; when the membrane flux drops to 1000 L / (m²·h), it is reversely flushed with clean water from the clean water tank, and the fallen filter cake is returned to the sewage pool for recycling.

[0031] Furthermore, the dosage of the sulfur powder is 40-60 g / L, preferably 50 g / L. The dosage of sulfur powder affects the formation process of the dynamic membrane and the thickness of the filter membrane. The present invention found that when the sulfur powder dosage is 50 g / L, the dynamic membrane is more uniform, and the membrane flux and effluent turbidity are both optimized.

[0032] In this embodiment, the particle size of sulfur powder is related to the transmembrane pressure, which affects the membrane flux and the turbidity of the effluent. The sulfur powder used for sulfur autotrophication is ground by a grinder and sieved by a vibrating screen to obtain sulfur powder with a particle size of 150-200 μm.

[0033] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A tubular dynamic membrane sulfur autotrophic denitrification device, characterized in that: include: The outer shell consists of a cylindrical structure in the middle and hemispherical structures at both ends. The upper part of the cylindrical structure is provided with a clean water outlet, the lower part is provided with a backwash port, and the top of the hemispherical structure is provided with a sewage inlet and a concentrated liquid outlet. A plurality of support bodies arranged in parallel, each support body comprising two layers of honeycomb PVC grids and a layer of polypropylene mesh, wherein the polypropylene mesh is sandwiched between the two layers of honeycomb PVC grids; Two diverter plates are fixed to the two ends of the support body respectively, and the diverter plates are provided with diverter holes corresponding to the support body; The inner cavity of the support body forms a filter chamber, the two diverter plates and the outer shell respectively form an inlet filter chamber and an outlet filter chamber, and a filter chamber is formed between the support body and the outer shell; sulfur powder dissolves in water to form a suspension, which enters the filter chamber and gradually forms a dynamic filter membrane on the polypropylene net. Sewage enters the filter chamber for sulfur autotrophic denitrification reaction.

2. The tubular dynamic membrane sulfur autotrophic denitrification device according to claim 1, characterized in that: The pore size of the polypropylene mesh is 100-150 μm, and the particle size of the sulfur powder is larger than the pore size of the polypropylene mesh.

3. The tubular dynamic membrane sulfur autotrophic denitrification device according to claim 2, characterized in that: The particle size of the sulfur powder is 150-200 μm.

4. The tubular dynamic membrane sulfur autotrophic denitrification device according to claim 1, characterized in that: The backwash port is arranged near the sewage inlet, and the clean water outlet is arranged near the concentrated liquid outlet.

5. The tubular dynamic membrane sulfur autotrophic denitrification device according to claim 1, characterized in that: The sewage inlet is connected to the sewage pool, the clean water outlet is connected to the clean water pool, and the tubular dynamic membrane sulfur autotrophic denitrification device operates in a manner of multiple membrane tubes connected in series.

6. The tubular dynamic membrane sulfur autotrophic denitrification device according to claim 1, characterized in that: The concentration of sulfur powder dissolved in water to form a suspension is 40-60g / L.

7. The tubular dynamic membrane sulfur autotrophic denitrification device according to claim 1, characterized in that: The honeycomb PVC grid and the polypropylene net are both cylindrical.

8. A tubular dynamic membrane sulfur autotrophic denitrification method, using the device according to any one of claims 1 to 7, characterized in that: The following steps are involved: Sulfur powder is added to the sewage pool to form a suspension, which is pumped into the filter chamber through the water inlet pump to form a sulfur powder pre-coating on the surface of the polypropylene mesh; Nitrate-containing wastewater is introduced in a cross-flow filtration mode, so that sludge microorganisms are attached to the pre-coating layer, and sulfur powder acts as an electron donor for denitrification.

9. The tubular dynamic membrane sulfur autotrophic denitrification method according to claim 8, characterized in that: The nitrogen generated during the denitrification reaction flushes the filter cake layer to maintain the membrane flux; when the membrane flux drops to 1000 L / (m²·h), it is reversely flushed with clean water from the clean water tank, and the fallen filter cake is returned to the sewage pool for recycling.

10. The tubular dynamic membrane sulfur autotrophic denitrification method according to claim 8, characterized in that: The dosage of the sulfur powder is 40-60 g / L, preferably 50 g / L.

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