A drawer type ceramic membrane rainwater treatment device and a rainwater treatment method

Abstract

This invention discloses a drawer-type ceramic membrane rainwater treatment device and method. The device includes an inlet pipe, a membrane tank, separation baskets, packing material, an outlet pipe, and a ceramic membrane. Multiple sets of parallel separation baskets are vertically arranged within the membrane tank. Each separation basket contains a ceramic membrane, and the outer side of the baskets is filled with packing material. The packing material creates an anoxic environment through stacking to enhance denitrification. The packing material and the ceramic membrane together form a packing-membrane composite zone within the membrane tank. The outlet of the inlet pipe is located above the packing material, and the outlet pipe is connected to the product water zone of the ceramic membrane. The treatment method involves rainwater entering the membrane tank through the inlet pipe, undergoing anoxic biological pretreatment for efficient nitrogen and phosphorus removal and pre-filtration, followed by deep filtration through the ceramic membrane, and then being discharged through the outlet pipe under gravity. This invention's treatment device features low energy consumption, outstanding denitrification effect, minimal membrane fouling, and easy disassembly and replacement of the ceramic membrane, making it suitable for urban rainwater purification and resource utilization.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a drawer-type ceramic membrane rainwater treatment device and rainwater treatment method. Background Technology

[0002] Urban rainwater resource utilization is an important way to alleviate urban water shortage. Traditional rainwater treatment processes such as sand filtration, sedimentation, and simple membrane filtration have the following defects: (1) poor removal effect on dissolved pollutants such as nitrogen and phosphorus, making it difficult to meet the requirements for reuse; (2) single membrane filtration is prone to membrane fouling, with short service life and high operating costs; (3) conventional biological treatment is difficult to construct a stable hypoxic environment, resulting in weak denitrification and low total nitrogen removal rate; (4) membrane module replacement and cleaning are inconvenient, and maintenance efficiency is low; (5) most devices require pump suction, resulting in high energy consumption.

[0003] Therefore, there is an urgent need to develop a rainwater treatment device that can enhance denitrification and reduce membrane fouling. Summary of the Invention

[0004] To address the technical problems existing in the prior art, the present invention aims to provide a drawer-type ceramic membrane rainwater treatment device and rainwater treatment method. This rainwater treatment device has a compact structure, stable operation, high denitrification efficiency, convenient maintenance, and extremely low energy consumption. It is widely applicable to the resource-based purification treatment of urban rainwater such as roof rainwater and road rainwater.

[0005] The objective of this invention is achieved through the following technical solution: a drawer-type ceramic membrane rainwater treatment device, comprising an inlet pipe, a membrane tank, separation baskets, packing material, an outlet pipe, and a ceramic membrane. Multiple parallel separation baskets are vertically arranged within the cavity of the membrane tank. The ceramic membrane is placed inside each separation basket, and the gaps between adjacent separation baskets are filled with the packing material. The packing material, through stacking, creates an anoxic environment to enhance denitrification. The packing material and the ceramic membrane together form a packing-membrane composite zone within the membrane tank. The outlet of the inlet pipe is located above the packing material, and the outlet pipe is connected to the water production zone of the ceramic membrane.

[0006] Furthermore, the inner side of the membrane tank and the separation basket are also filled with the filler; the separation basket is a frame-type drawer structure, which is formed by four sides and has a top opening, through which the ceramic membrane can be inserted or removed; the four sides are provided with multiple through holes to allow water to pass through.

[0007] Specifically, the ceramic membrane is a flat ceramic membrane.

[0008] Furthermore, a biofilm is attached to the surface of the ceramic membrane.

[0009] Preferably, the effective membrane area of ​​the ceramic membrane is 0.1~0.5 m². 2 .

[0010] Preferably, the filler is ceramsite or pyrite.

[0011] Preferably, the particle size of the ceramsite or pyrite is 1-5 mm, and the filling thickness is 100-200 mm.

[0012] Specifically, the rainwater treatment device is driven to discharge water by a gravity head of more than 0.5 m.

[0013] This invention provides another technical solution: a rainwater treatment method using the aforementioned drawer-type ceramic membrane rainwater treatment device. The method includes the following steps: First, the water to be treated enters the membrane tank through the inlet pipe and flows from top to bottom through the packing material zone. The water to be treated flows slowly in the gaps of the packing material, and the densely packed packing material creates an anoxic environment, removing total nitrogen through microbial denitrification and simultaneously achieving pre-filtration of suspended solids. Then, the pre-treated water enters the ceramic membrane for deep filtration to remove colloids, particulate matter, and residual organic matter. Finally, the purified effluent is discharged through the outlet pipe under gravity.

[0014] Furthermore, the packing material provides a carrier for microorganisms to attach and form a biofilm, thereby achieving the simultaneous removal of nitrogen, phosphorus, and organic matter from the water to be treated.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: 1. This invention enhances denitrification by creating an oxygen-deficient environment through packing material, achieving a nitrogen removal rate of over 70% after the drying period; and significantly reduces membrane fouling through a combination of packing material pre-filtration and ceramic membrane fine filtration.

[0016] 2. This invention enables drawer-type plug-in installation of ceramic membranes through a separate basket, making the replacement and maintenance of ceramic membranes convenient and quick.

[0017] 3. This invention can drive water output through gravity head, which is purely gravity driven and requires no water pump or aeration, with energy consumption of almost zero.

[0018] 4. The present invention preferably uses ceramsite or pyrite, and denitrification and phosphorus removal can be flexibly enhanced.

[0019] 5. The device of the present invention has a compact structure and a small footprint, making it suitable for decentralized rainwater treatment. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the device of the present invention.

[0021] Figure 2 This is a schematic diagram of the structure of the device of the present invention after being cut apart.

[0022] Figure 3 This is a schematic diagram of the structure of the ceramic membrane assembly of the device of the present invention.

[0023] Figure 4 This is a schematic diagram of the water flow path and the distribution of the anoxic zone in the device of the present invention.

[0024] Figure 5 The graph shows the change in membrane flux over time under the conditions of ceramsite and pyrite.

[0025] Figure 6 This is a comparison chart showing the pollutant removal effects of two different fillers: ceramsite and pyrite.

[0026] In the picture: 1-Inlet pipe, 2-Membrane tank, 3-Separation basket, 4-Packing material, 5-Outlet pipe, 6-Ceramic membrane, 601-Membrane body, 602-Upper collection tank, 603-Lower collection tank, 604-Outlet of ceramic membrane. Detailed Implementation

[0027] To facilitate understanding of the present invention, the technical solutions and advantages of the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Any mechanisms or methods not elaborated in this invention can be referred to in the prior art. The specific structures and features of the present invention are illustrated below by way of example and should not be construed as limiting the present invention in any way. Furthermore, any of the technical features mentioned below (including implicit or disclosed features), as well as any technical features directly shown or implied in the figures, can be arbitrarily combined or deleted among these technical features to form more other embodiments that may not be directly or indirectly mentioned in this invention. The accompanying drawings show preferred embodiments of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0028] like Figure 1-4 As shown, the drawer-type ceramic membrane rainwater treatment device of the present invention includes an inlet pipe 1, a membrane tank 2, a separation basket 3, a packing material 4, an outlet pipe 5, and a ceramic membrane 6.

[0029] Specifically, the membrane tank 2 is a closed or open structure with an opening at the top. The inlet pipe 1 is located above the membrane tank, and the outlet of the inlet pipe 1 is connected to the cavity of the membrane tank 2. Multiple parallel separation baskets 3 are arranged vertically inside the cavity of the membrane tank 2. There are gaps between adjacent separation baskets 3, and there are also gaps between the inner side of the membrane tank 2 and the separation baskets 3.

[0030] The separation basket 3 is a frame-type drawer structure, which is surrounded by four sides and has a top opening. Multiple through holes are arranged in an array on the four sides to allow water to pass through.

[0031] A ceramic membrane 6 is built into the separation basket 3. The inner side of the separation basket 3 is in close contact with the ceramic membrane 6. The ceramic membrane 6 can be inserted or removed through the top opening of the separation basket 3 for easy cleaning and replacement. The ceramic membrane 6 forms a membrane filtration zone. The gaps between adjacent separation baskets 3 are filled with packing material 4, and the inner side of the membrane tank 2 and the separation basket 3 are also filled with packing material 4. The area filled with packing material is called the packing material zone.

[0032] The packing zone and the membrane filtration zone together form a packing-membrane composite zone within the membrane tank, with the lower outlet of the inlet pipe 1 directly above the packing 4. The packing 4 is densely packed, and water flows slowly through it, creating a stable anoxic environment to enhance denitrification. Preferably, the particle size of the ceramsite or pyrite is 1-5 mm, and the packing thickness is 100-200 mm.

[0033] In this embodiment, the filler 4 is preferably ceramsite or pyrite. Ceramsite has well-developed pores, a large specific surface area, and stable properties. It has good water permeability and water storage, as well as the ability to adsorb pollutants and form biofilms. Pyrite can enrich sulfur autotrophic denitrifying bacteria and alleviate the problem of low carbon-nitrogen ratio in rainwater.

[0034] The ceramic membrane 6 is a flat-sheet ceramic membrane, comprising a membrane body 601, an upper collection tank 602, a lower collection tank 603, and an outlet 604. The upper collection tank 602 and the lower collection tank 603 are respectively connected to the upper and lower parts of the membrane body 601. The outlet 604 of the ceramic membrane is embedded in the upper collection tank 602 and communicates with the product water zone of the membrane body 601. Preferably, a biofilm is attached to the surface of the ceramic membrane 6 for further nitrogen and phosphorus removal and to mitigate membrane fouling. The inner side of the ceramic membrane 6 is the product water zone, and the outer side of the ceramic membrane 6 is the raw water zone.

[0035] The water outlet pipe 5 is connected to the water production area of ​​the ceramic membrane 6 through the water outlet 604 of the ceramic membrane.

[0036] The device of the present invention relies on gravity to drive the water output.

[0037] The rainwater treatment method of the present invention includes the following steps: First, the water to be treated enters the membrane tank 2 through the inlet pipe 1 and flows from top to bottom through the packing zone. The water flows slowly through the gaps in the packing 4, and the densely packed packing 4 creates an anaerobic environment, removing total nitrogen through microbial denitrification and simultaneously pre-filtering suspended solids. Then, the pre-treated water enters the ceramic membrane 6 for deep filtration to remove colloids, particulate matter, and residual organic matter. Finally, the purified effluent flows into the outlet pipe 5 and is discharged under gravity.

[0038] The following examples illustrate this. Example 1

[0039] In this embodiment 1, ceramsite is used as the filler, with a particle size of 3-5 mm and a filling thickness of 150 mm. The ceramic membrane is a flat ceramic membrane with an effective membrane area of ​​0.1 m², and the device is driven to output water by a gravity head of 0.5 m.

[0040] The operation of the device in Example 1 is divided into an initial biofilm culture stage and an intermittent operation stage: 1) Early cultivation stage: Simulated rainwater is continuously introduced to carry out biofilm cultivation, so that a stable biofilm is formed between the packing material and the ceramic membrane surface; 2) Intermittent operation phase: The rainwater inlet-drying cycle mode was adopted, and four working conditions were set with drying periods of 24 days, 3 days, 7 days and 10 days respectively to investigate the impact of different drying times on the treatment effect of the device. Example 2

[0041] In Example 2, pyrite was used as the filler with a particle size of 1-3 mm. The rest of the device structure and operation were exactly the same as in Example 1. After the initial biofilm cultivation, the system entered a rainwater inlet-drying cycle, with four operating conditions set for drying periods of 24 days, 3 days, 7 days, and 10 days.

[0042] Based on the rainfall-inlet-drying cycle operation conditions of Examples 1 and 2, the membrane flux changes of the two systems with ceramsite packing and pyrite packing were continuously monitored over the long term, and the curves in Figure 5 were plotted. Figure 5 In this context, Ceramsite refers to the experimental data from Example 1, and Iron pyrite refers to the experimental data from Example 2. As shown in Figure 5, the experimental data indicates that: Throughout the entire process of alternating drying cycles of 24 days, 3 days, 7 days, and 10 days, the membrane flux of the ceramsite packing group remained stable at around 9 LMH, while the membrane flux of the pyrite packing group remained stable at around 10 LMH. The membrane flux of the two packing groups fluctuated very little with the operating time, with no obvious rapid decline or clogging.

[0043] Experimental results demonstrate that the composite filtration structure of this invention, consisting of pre-filtration with packing material and fine filtration with a flat ceramic membrane, can effectively trap suspended solids and colloidal impurities in rainwater, significantly delaying clogging and fouling on the ceramic membrane surface. Simultaneously, the stable, oxygen-deficient biological environment prevents the accumulation of biological slime, and the membrane flux remains stable and consistent under long-term gravity-driven operation, significantly reducing the membrane fouling rate and extending the lifespan of the ceramic membrane. This effectively solves the technical defects of traditional rainwater membrane treatment devices, such as easy clogging, rapid flux decay, and frequent cleaning and replacement.

[0044] Based on the results of the comparative tests of rainwater pollutant purification efficiency of two different packing materials, ceramsite packing and pyrite packing, under the same gravity head, same drying cycle, and same operating conditions, in Examples 1 and 2, the following conclusions were drawn. Figure 6 ,in, Figure 6 In this context, Ceramsite refers to the experimental data of Example 1, Iron pyrite refers to the experimental data of Example 2, and Influent refers to the raw water (data of the simulated rainwater used for treatment).

[0045] The results are shown below.

[0046] Turbidity index: The turbidity removal rate of the ceramsite packing group is stable at over 95%, and the turbidity removal rate of the pyrite packing group is over 96%. Both groups have extremely high suspended solids purification effect, and the effluent is clear and stable. Total nitrogen removal index: The average total nitrogen removal rate of the ceramsite packing group is about 70%, and the average total nitrogen removal rate of the pyrite packing group is about 60%. Moreover, it was found that the total nitrogen removal rate was only so high a few days after the drying period, which is speculated to be related to the length of the drying period. The drying period refers to the time without water intake, that is, the interval between the current rainfall and the next rainfall. Total phosphorus removal indicators: The total phosphorus removal rate of the ceramsite packing group is about 36%; the pyrite system can simultaneously enhance biological denitrification and chemical phosphorus removal, and maintain high efficiency and stability under different drying conditions. The total phosphorus removal rate of the pyrite packing group is about 45%, achieving simultaneous and differentiated high-efficiency purification of nitrogen and phosphorus. Organic matter indicators: two groups of UV 254 The removal rate is consistently around 60%, which can effectively remove dissolved organic matter from rainwater.

[0047] The comparative data in Figure 6 fully demonstrates that the present invention can flexibly select two types of fillers, ceramsite and pyrite, to respectively enhance biological denitrification and simultaneous denitrification and phosphorus removal. Under the intermittent operation mode of alternating dry and wet urban rainwater, the device has excellent and stable comprehensive purification effects of denitrification, phosphorus removal, turbidity removal and organic matter removal, and the anoxic denitrification enhancement effect is significant. The quality of rainwater effluent meets the requirements for resource reuse, and the comprehensive performance of denitrification and phosphorus removal is greatly improved compared with traditional rainwater treatment processes.

[0048] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, it will be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A drawer-type ceramic membrane rainwater treatment device, characterized in that, The device includes an inlet pipe, a membrane tank, separation baskets, packing material, an outlet pipe, and a ceramic membrane. Multiple parallel separation baskets are vertically arranged within the cavity of the membrane tank. The ceramic membrane is placed inside each separation basket, and the gaps between adjacent separation baskets are filled with packing material. The packing material creates an anoxic environment through stacking to enhance denitrification. The packing material and the ceramic membrane together form a packing-membrane composite zone within the membrane tank. The outlet of the inlet pipe is located above the packing material, and the outlet pipe is connected to the product water zone of the ceramic membrane.

2. The drawer-type ceramic membrane rainwater treatment device as described in claim 1, characterized in that, The inner side of the membrane tank is also filled with the filler between it and the separation basket; the separation basket is a frame-type drawer structure, which is formed by four sides and has a top opening, through which the ceramic membrane can be inserted or removed; the four sides are provided with multiple through holes to allow water to pass through.

3. The drawer-type ceramic membrane rainwater treatment device as described in claim 1, characterized in that, The ceramic membrane is a flat ceramic membrane.

4. The drawer-type ceramic membrane rainwater treatment device as described in claim 3, characterized in that, The surface of the ceramic membrane is covered with a biofilm.

5. The drawer-type ceramic membrane rainwater treatment device as described in claim 3, characterized in that, The effective membrane area of ​​the ceramic membrane is 0.1~0.5 m².

6. The drawer-type ceramic membrane rainwater treatment device as described in claim 1, characterized in that, The filler is ceramsite or pyrite.

7. The drawer-type ceramic membrane rainwater treatment device as described in claim 6, characterized in that, The particle size of the ceramsite or pyrite is 1-5 mm, and the filling thickness is 100-200 mm.

8. The drawer-type ceramic membrane rainwater treatment device as described in claim 1, characterized in that, Water is driven out by gravity head of more than 0.5 m.

9. A rainwater treatment method, characterized in that, The drawer-type ceramic membrane rainwater treatment device according to any one of claims 1-8 comprises the following steps: First, the water to be treated enters the membrane tank through the inlet pipe and flows from top to bottom through the packing area. The water to be treated flows slowly in the gaps of the packing, and the densely packed packing creates an anoxic environment, removing total nitrogen through microbial denitrification and simultaneously achieving pre-filtration of suspended solids; then, the pre-treated water enters the ceramic membrane for deep filtration to remove colloids, particulate matter, and residual organic matter; finally, the purified effluent is discharged into the outlet pipe under gravity.

10. The rainwater treatment method as described in claim 9, characterized in that, The packing material provides a carrier for microorganisms to attach and form a biofilm, thereby achieving the simultaneous removal of nitrogen, phosphorus and organic matter from the water to be treated.

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