An artificial wetland device and method for enhancing water circulation in a wetland without external power

Abstract

The application discloses an artificial wetland device and method for reinforcing water circulation in a wetland without external power, which comprises a shell and a filler layer, wherein the shell comprises an outer shell, a baffle and an overflow weir; the baffle is vertically arranged in the inner part of the outer shell and divides the shell into a water inlet chamber and a water outlet chamber; the baffle is arranged at a distance from the bottom of the outer shell to form a water passing channel; a water inlet is arranged on the side wall of the water inlet chamber; a water outlet is arranged on the middle area of the side wall of the water outlet chamber; a backflow port is arranged above the baffle; the backflow pipe is of a reduced diameter structure; the large-diameter end of the backflow pipe is connected with the backflow port, and the small-diameter end extends downwardly and obliquely in the water inlet chamber; the overflow weir is arranged outside the water outlet and surrounds the overflow chamber with the side wall of the water outlet chamber; and the heights of the outer shell, the baffle, the overflow weir, the backflow port and the water outlet are sequentially reduced.

Description

Technical Field

[0001] This invention belongs to the field of constructed wetland technology for wastewater treatment, specifically relating to a constructed wetland device and method for enhancing water circulation within the wetland without external power. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Small-scale constructed wetland devices (or structures) play a crucial role in water resource protection and recycling as a highly efficient and environmentally friendly wastewater treatment facility. Their main applications are concentrated in rural small-scale wastewater treatment plants and household ecological water purification devices.

[0004] The water purification effect of this type of device is mainly achieved through the synergistic action of physical, chemical, and biological processes. Wastewater first passes through the substrate layer of the constructed wetland, where the substrate filters and adsorbs suspended particles, initially removing large particulate impurities. Subsequently, microorganisms decompose and transform pollutants such as organic matter, nitrogen, and phosphorus in the wastewater under aerobic and anaerobic conditions. For example, under aerobic conditions, aerobic microorganisms oxidize and decompose organic matter into carbon dioxide and water, while simultaneously converting ammonia nitrogen into nitrate nitrogen; in the anaerobic zone, denitrifying bacteria use organic matter as a carbon source to reduce nitrate nitrogen into nitrogen gas, which is released into the atmosphere, thus achieving denitrification.

[0005] In terms of configuration, small-scale constructed wetland devices (or structures) mostly adopt a top-in, bottom-out water flow method, and are equipped with overflow weirs and drainage pipes. Wastewater enters from the top of the device, is evenly distributed on the wetland surface, and then slowly seeps downwards. After being purified layer by layer by the substrate layer and microbial community, it flows out from the bottom. The overflow weir plays a role in controlling the water level and drainage, ensuring that the device can operate stably under different water volume conditions.

[0006] However, in actual operation, some problems exist on the surface of small-scale constructed wetland devices (or structures): Due to the high carbon, nitrogen, and phosphorus content in rural and domestic sewage, abundant nutrients are provided for the growth and reproduction of microorganisms, leading to vigorous microbial growth. Excessive microbial growth easily accumulates on the wetland surface, causing blockages and affecting the normal flow and treatment efficiency of sewage. Simultaneously, the high concentration of organic matter causes COD degradation to occur too quickly. As sewage flows through the wetland surface, most of the organic matter is rapidly consumed, resulting in a lack of sufficient carbon source for denitrification at the bottom, hindering the full progress of denitrification and significantly reducing nitrogen removal efficiency. Further extended water quality analysis indicates that at the downstream end of the wetland device, due to the rapid removal of pollutants in the earlier stages, the purification effect gradually weakens, failing to fully realize the treatment potential of the entire wetland system.

[0007] In addition, some wetlands employ iron ore matrix enhancement for pollutant removal. In aerobic zones, iron is oxidized, promoting the adsorption and oxidative decomposition of pollutants; in anoxic zones, iron undergoes reduction reactions, also aiding in pollutant removal. However, a current problem is that the entire system lacks an effective Fe cycle due to the constant spatial direction of water flow and physicochemical conditions. Iron is gradually fixed or lost with the effluent during the redox process, failing to continuously and effectively participate in pollutant removal reactions. This, to some extent, limits the long-term stability and effectiveness of iron ore matrix enhancement. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the purpose of this invention is to provide an artificial wetland device and method for enhancing water circulation within wetlands without external power.

[0009] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0010] In a first aspect, the present invention provides an artificial wetland device for enhancing water circulation within a wetland without external power, comprising a shell and a packing layer, wherein the shell includes an outer shell, a baffle, and an overflow weir, wherein...

[0011] The baffle is vertically installed inside the shell, dividing the interior of the shell into an inlet chamber and an outlet chamber. The bottom of the baffle is spaced a certain distance from the bottom of the shell to form a water passage. An inlet is provided on the side wall of the inlet chamber, and an outlet is provided in the middle area of ​​the side wall of the outlet chamber.

[0012] A return port is provided above the baffle. The return pipe has a reduced diameter structure. The large diameter end of the return pipe is connected to the return port, and the small diameter end extends downward at an angle in the water inlet chamber.

[0013] The overflow weir is located on the outside of the outlet, forming an overflow cavity with the side wall of the outlet chamber;

[0014] The heights of the outer shell, baffle, overflow weir, return outlet, and outlet decrease sequentially.

[0015] The bottom of the baffle is set at a certain distance from the bottom of the outer shell to form a water passage, so that the sewage entering from the inlet can flow through the water passage into the outlet chamber during the treatment process, and the treated water flows out to the overflow chamber through the outlet.

[0016] The height of the outer shell, baffle, overflow weir, return outlet and outlet decreases in sequence. The overflow weir here plays the role of controlling the water level inside the artificial wetland, so that the water level inside is higher than the outlet and return outlet, which makes the water flow speed in the area between the outlet and return outlet in the outlet chamber very slow, forming a still water zone.

[0017] The water level in the inlet chamber is also controlled by the height of the overflow weir, ensuring that the water level in the inlet chamber is higher than the height of the return outlet, and that the water flow velocity is greater than the water flow velocity in the area between the outlet and the return outlet in the outlet chamber. This ensures that the treated water in the outlet chamber flows back to the inlet side of the inlet chamber. On the one hand, the returned water can dilute the sewage inlet to reduce the carbon, nitrogen, and phosphorus content in the sewage, which can inhibit the growth and reproduction of microorganisms to a certain extent. This can effectively prevent the blockage of the wetland filler and ensure the normal flow and treatment efficiency of sewage.

[0018] After the influent wastewater is diluted, the consumption of organic matter slows down as the wastewater flows across the wetland surface. This provides a sufficient carbon source for the denitrification process in the lower layers, ensuring the effectiveness of denitrification treatment and thus improving the overall wastewater treatment effect.

[0019] For wetlands using iron ore substrates, the water flowing back from the effluent chamber to the influent chamber can also recycle some iron back into the influent chamber, which slows down iron loss to a certain extent and helps to further improve the wastewater treatment effect.

[0020] Because the water flow velocity is relatively high on the inlet side of the water inlet chamber, it may enter the outlet chamber through the return port, contaminating the purified water in the outlet chamber. Designing the return pipe as a reduced-diameter structure and tilting it downwards can effectively prevent wastewater from the inlet chamber from entering the outlet chamber.

[0021] In some embodiments, the height of the inlet is higher than the height of the overflow weir.

[0022] In some embodiments, the opening diameter of the reflux port is 1-100cm, preferably 2-10cm, and more preferably 2-5cm.

[0023] Preferably, the length of the return pipe is 2-20cm, more preferably 5-10cm. The number of return pipes is not limited and can be adjusted according to specific working conditions.

[0024] More preferably, the ratio of the inner diameter of the small-diameter end to the inner diameter of the large-diameter end of the return pipe is 1:1.5-10, more preferably 1:2-5, and even more preferably 1:2-3.

[0025] More preferably, the included angle between the return pipe and the baffle is 20°-45°, and more preferably 30°-45°.

[0026] In some embodiments, the packing layer is located below the inlet chamber and outlet chamber, and below the return pipe and outlet.

[0027] Preferably, the filler layer comprises an iron-rich mineral matrix, ceramsite, zeolite, and gravel, wherein the iron-rich mineral matrix comprises 10%-20% by mass, and the ceramsite, zeolite, and gravel have a particle size of 0.4-3 cm.

[0028] More preferably, cattails and canna lilies are planted on top of the filler layer at a planting density of 5-40 plants / m². 2 The preferred density is 20-30 plants / m². 2 .

[0029] Secondly, the present invention provides a method for enhancing water circulation in wetlands without external power, which is achieved by using the artificial wetland device: wastewater is transported to the inlet chamber through the inlet, and after being treated by the wetland filler, it enters the outlet chamber. Part of the purified water enters the overflow chamber through the outlet and flows out through the overflow weir.

[0030] Under the action of the overflow weir, the artificial wetland device maintains a set liquid level, which is higher than the height of the return port and the outlet, so that a still water zone is formed between the return port and the outlet of the outlet chamber.

[0031] A pressure difference is formed between the dynamic water zone and the static water zone of the inlet chamber through the return port. The purified water in the static water zone flows back to the dynamic water zone under the action of the pressure difference, which dilutes the inlet sewage.

[0032] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows:

[0033] The height of the outer shell, baffle, overflow weir, return outlet and outlet decreases in sequence. The overflow weir here plays the role of controlling the water level inside the artificial wetland, so that the water level inside is higher than the outlet and return outlet, which makes the water flow speed in the area between the outlet and return outlet in the outlet chamber very slow, forming a still water zone.

[0034] The water level in the inlet chamber is also controlled by the height of the overflow weir, ensuring that the water level in the inlet chamber is higher than the height of the return outlet, and that the water flow velocity is greater than the water flow velocity in the area between the outlet and the return outlet in the outlet chamber. This ensures that the treated water in the outlet chamber flows back to the inlet side of the inlet chamber. On the one hand, the returned water can dilute the sewage inlet to reduce the carbon, nitrogen, and phosphorus content in the sewage, which can inhibit the growth and reproduction of microorganisms to a certain extent. This can effectively prevent the blockage of the wetland filler and ensure the normal flow and treatment efficiency of sewage.

[0035] After the influent wastewater is diluted, the consumption of organic matter slows down as the wastewater flows across the wetland surface. This provides a sufficient carbon source for the denitrification process in the lower layers, ensuring the effectiveness of denitrification treatment and thus improving the overall wastewater treatment effect.

[0036] For wetlands using iron ore substrates, the water flowing back from the effluent chamber to the influent chamber can also recycle some iron back into the influent chamber, which slows down iron loss to a certain extent and helps to further improve the wastewater treatment effect. Attached Figure Description

[0037] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0038] Figure 1 This is a schematic diagram of the structure of the artificial wetland device of the present invention;

[0039] Figure 2 This is an enlarged structural schematic diagram of the reflux tube of the present invention.

[0040] Among them, 1-return outlet; 2-still water zone; 3-inlet; 4-outlet; 5-overflow weir. Detailed Implementation

[0041] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0042] The present invention will be further described below with reference to the embodiments.

[0043] Example

[0044] To improve the overall performance of small-scale constructed wetland systems (or structures), enhance the role of organic carbon in denitrification, and reduce iron loss, strengthening internal circulation is a highly promising optimization strategy. Strengthening internal circulation effectively dilutes surface pollutant concentrations. By returning some treated water to the front end of the system, the concentration of pollutants entering the surface wastewater is reduced, thus mitigating the risk of bioclogging. Through internal circulation, pollutants are dispersed to different areas, allowing for a more balanced application of treatment functions across different areas. It also provides more carbon sources for downstream denitrification, ensuring its smooth progress and improving nitrogen removal efficiency. Furthermore, in wetlands enhanced with variable valence metals, internal circulation allows metal ions to continuously circulate within the system, participating in redox reactions and maintaining the stability and effectiveness of their enhancement effect.

[0045] One common method of circulation is recirculation, but this usually requires power. Pumps or similar equipment can be used to pump a portion of the treated water back to the vicinity of the inlet. Considering the energy consumption and cost of externally powered recirculation, this paper proposes a method to enhance water circulation within the wetland without external power. This allows the internal circulation to achieve maximum efficiency in small-scale constructed wetland devices, improving overall wastewater treatment capacity and promoting its widespread application in rural small-scale wastewater treatment plants and household ecological water purification systems. A schematic diagram is shown below. Figure 1 As shown:

[0046] An artificial wetland device for enhancing water circulation within a wetland without external power supply includes a shell and a packing layer. The shell comprises an outer shell, baffles, and an overflow weir 5.

[0047] The baffle is vertically installed inside the shell, dividing the interior of the shell into an inlet chamber and an outlet chamber. The bottom of the baffle is spaced a certain distance from the bottom of the shell to form a water passage. An inlet 3 is provided on the side wall of the inlet chamber, and an outlet 4 is provided in the middle area of ​​the side wall of the outlet chamber.

[0048] A return port 1 is provided above the baffle. The return pipe has a reduced diameter structure, with the larger diameter end of the return pipe connected to the return port 1, and the smaller diameter end extending downwards at an angle within the water inlet chamber. Figure 2 As shown;

[0049] The overflow weir 5 is located on the outside of the outlet, forming an overflow cavity with the side wall of the outlet chamber;

[0050] The heights of the outer shell, baffle, overflow weir 5, return port 1 and outlet 4 decrease sequentially, and the height of the inlet is higher than that of the overflow weir.

[0051] The upper left side of the baffle continuously receives water, while outlet 4 is located in the middle right side. An overflow plate surrounds outlet 4, forming an overflow weir at its top. Wastewater enters from the upper left side, flows through the bottom, and continuously exits from the middle right side. The liquid levels on both sides of the constructed wetland and in the overflow weir area are level. Multiple channels are installed in the upper half of the middle baffle, above the outlet height, connecting to a gradually decreasing diameter pipe towards the left inlet. The pipe is 2-10cm long, with its diameter gradually decreasing from 3cm to 1cm at the connection point, and slopes downwards at 45-60°. The number of channels depends on the required return flow. The gradually decreasing diameter and downward slope increase resistance to flow from left to right, reducing the flow of liquid from left to right.

[0052] A packing layer is installed at the bottom of the left inlet chamber, with 10-20% Fe-rich mineral matrix and 80-90% conventional matrix added to the packing layer.

[0053] The Fe-rich mineral matrix provides electrons for nitrate reduction and is itself converted into Fe.2+ Fe 3+ Driven by the water recirculation, the aerobic particles enter the upper aerobic zone and can be used for ammonia nitrogen oxidation, achieving recycling. Conventional substrates include ceramsite, zeolite, and gravel, with particle sizes ranging from 0.4 to 3 cm.

[0054] The upper part of the filler layer is planted with two emergent aquatic flowers, cattail and canna lily, at a planting density of 25 plants / m². 2 Within the range.

[0055] The water flow in the area between the outlet and return port of the right outlet chamber is very weak, while the water flow in the left inlet chamber is fast. The difference in water flow velocity on both sides creates a pressure difference, which pushes the purified water on the right back to the sewage on the left, forming a backflow, diluting the inlet water, reducing blockage, and facilitating the recycling of variable valence metals in the system. At the same time, it dilutes the concentration of organic carbon at the inlet end, better enabling the denitrification function at the lower end.

[0056] Specifically, a small-scale artificial wetland water purification device was simulated in the laboratory using a cylindrical container made of HDPE material. The device was 15.7cm high and had a bottom diameter of 9.2cm. Inside, a 14cm long HDPE baffle divided the device into two interconnected sides at the bottom. The distance between the baffle and the bottom was 3cm. A 2.1cm long constriction tube was used to simulate a return pipe and was installed in the upper part of the baffle. The diameter of the return port was 1cm, and the inner diameter of the small diameter end of the return pipe was 0.3cm. There were 3 return pipes, and the angle between the return pipe and the baffle was 45°. The height of the outlet was 8cm.

[0057] Water enters from the upper left side of the constructed wetland device at a flow velocity of 15.7 cm. 3 / s; An outlet is set in the middle of the right side, raised to a height of 13.7cm to simulate a wetland overflow weir, and the water level inside the device is maintained at 13.7cm.

[0058] The design of the inlet and outlet water structure creates a still water zone on the upper right side of the device. Ink is dropped directly above the still water zone on the right, and a timer is set for 10 seconds from the start of the drop. The amount of ink on both sides is characterized using spectrophotometry. Based on the distribution pattern, the probability of the particles in the still water zone flowing back to the inlet water zone on the left is calculated; this is the water backflow rate.

[0059] Multiple parallel experiments revealed that the water recirculation rate ranged from 5.6% to 13.1%. If the continuous water inflow on the left side was removed, the recirculation rate after 10 seconds was only about 2.6%, confirming the improved performance of the recirculation pipe on internal water circulation under continuous operation mode. This also demonstrated the mixing effect of water-soluble components such as organic carbon and iron ions in a real wetland, thereby enhancing the wastewater treatment capacity of the wetland device.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An artificial wetland device for enhancing water circulation within a wetland without external power, characterized in that: It includes a shell and a packing layer, wherein the shell includes an outer shell, a baffle, and an overflow weir, wherein, The baffle is vertically installed inside the shell, dividing the interior of the shell into an inlet chamber and an outlet chamber. The bottom of the baffle is spaced a certain distance from the bottom of the shell to form a water passage. An inlet is provided on the side wall of the inlet chamber, and an outlet is provided in the middle area of ​​the side wall of the outlet chamber. A return port is provided above the baffle. The return pipe has a reduced diameter structure. The large diameter end of the return pipe is connected to the return port, and the small diameter end extends downward at an angle in the water inlet chamber. The overflow weir is located on the outside of the outlet, forming an overflow cavity with the side wall of the outlet chamber; The heights of the outer shell, baffle, overflow weir, return outlet, and outlet decrease sequentially.

2. The artificial wetland device for enhancing water circulation within the wetland without external power, as described in claim 1, is characterized in that: The height of the inlet is higher than the height of the overflow weir.

3. The artificial wetland device for enhancing water circulation within the wetland without external power, as described in claim 1, is characterized in that: The opening diameter of the reflux port is 1-100cm.

4. The artificial wetland device for enhancing water circulation within the wetland without external power, as described in claim 3, is characterized in that: The opening diameter of the reflux port is 2-10cm.

5. The artificial wetland device for enhancing water circulation within the wetland without external power, as described in claim 4, is characterized in that: The opening diameter of the reflux port is 2-5 cm.

6. The artificial wetland device for enhancing water circulation within the wetland without external power, as described in claim 5, is characterized in that: The length of the reflux pipe is 2-20cm.

7. The artificial wetland device for enhancing water circulation within the wetland without external power as described in claim 6, characterized in that: The length of the reflux tube is 5-10cm.

8. The artificial wetland device for enhancing water circulation within the wetland without external power, as described in claim 3, is characterized in that: The ratio of the inner diameter of the small-diameter end to the inner diameter of the large-diameter end of the return pipe is 1:1.5-10.

9. The artificial wetland device for enhancing water circulation within the wetland without external power, as described in claim 8, is characterized in that: The ratio of the inner diameter of the small-diameter end to the inner diameter of the large-diameter end of the return pipe is 1:2-5.

10. The artificial wetland device for enhancing water circulation within the wetland without external power, as described in claim 9, is characterized in that: The ratio of the inner diameter of the small-diameter end to the inner diameter of the large-diameter end of the return pipe is 1:2-3.

11. The artificial wetland device for enhancing water circulation within the wetland without external power, as described in claim 8, is characterized in that: The angle between the return pipe and the baffle is 20°-45°.

12. The artificial wetland device for enhancing water circulation within the wetland without external power, as described in claim 11, is characterized in that: The angle between the return pipe and the baffle is 30°-45°.

13. The artificial wetland device for enhancing water circulation within the wetland without external power, as described in claim 1, is characterized in that: The packing layer is located below the inlet and outlet chambers, and below the return pipe and outlet.

14. The artificial wetland device for enhancing water circulation within the wetland without external power, as described in claim 13, is characterized in that: The filler layer includes an iron-rich mineral matrix, ceramsite, zeolite, and gravel, wherein the iron-rich mineral matrix comprises 10%-20% by mass, and the ceramsite, zeolite, and gravel have a particle size of 0.4-3 cm.

15. The artificial wetland device for enhancing water circulation within the wetland without external power, as described in claim 14, is characterized in that: Cattails and Thalia dealbata are planted on top of the filler layer, with a planting density of 5-40 plants / m². 2 .

16. The artificial wetland device for enhancing water circulation within the wetland without external power, as described in claim 15, is characterized in that: The planting density of cattails and canna lilies above the filler layer is 20-30 plants / m². 2 .

17. A method for enhancing water circulation in wetlands without external power, characterized in that: The artificial wetland device according to any one of claims 1-16 is used to achieve the following: wastewater is transported to the inlet chamber through the inlet, and after being treated by the wetland filler, it enters the outlet chamber. Part of the purified water enters the overflow chamber through the outlet and flows out through the overflow weir. Under the action of the overflow weir, the artificial wetland device maintains a set liquid level, which is higher than the height of the return port and the outlet, so that a still water zone is formed between the return port and the outlet of the outlet chamber. A pressure difference is formed between the dynamic water zone and the static water zone of the inlet chamber through the return port. The purified water in the static water zone flows back to the dynamic water zone under the action of the pressure difference, which dilutes the inlet sewage.

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