Device for continuous sampling and in-situ monitoring of constructed wetlands and method of use

Abstract

The present application relates to a device for continuous sampling and in-situ monitoring inside constructed wetland and a use method, belonging to the field of wastewater treatment, the device comprises an outer frame, one or more substrate sampling cylinders and an in-situ monitoring cylinder, the outer frame is a three-dimensional square frame, and the outer frame is composed of a grid around; the substrate sampling cylinder is a multilayer square grid cylinder placed inside the outer frame, and the grid diameter is consistent with the substrate particle size; the in-situ monitoring cylinder is placed inside the substrate sampling cylinder without stratification, used for water sampling and in-situ monitoring of environmental parameters; the in-situ monitoring cylinder has no bottom up and down, and the peripheral wall has water-permeable holes, and is in the same height with the substrate sampling cylinder. By using the device, the substrate and water quality inside the constructed wetland can be easily sampled multiple times in the running process without damaging the substrate structure of the constructed wetland, and the environmental parameters such as dissolved oxygen, temperature, salinity and pH can be long-term in-situ monitored.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of wastewater treatment, and particularly relates to a device for continuous sampling and in-situ monitoring inside a constructed wetland and a use method. BACKGROUND

[0002] A constructed wetland is a kind of ecological wastewater treatment technology composed of plants, substrates and microorganisms, and has the advantages of low operation cost, convenient management and great carbon neutralization potential. In recent decades, more and more constructed wetlands have been put into use to treat wastewater from different sources, such as tail water of municipal wastewater treatment plants, aquaculture wastewater, landfill leachate, runoff rainwater and the like. Researchers have also increasingly studied constructed wetlands.

[0003] The change of the community structure of microorganisms inside a constructed wetland plays a crucial role in water quality improvement. Water quality and microorganisms are two important objects of attention for the research and operation management of a constructed wetland. Microorganisms mainly attach to the surface of substrates inside the wetland to form biofilms. Due to the difficulty in obtaining samples inside a constructed wetland during operation, researchers can only sample and study the influent and effluent water and the surface layer of the substrate. This restricts researchers from conducting in-depth research on the succession and role of the microbial community inside a constructed wetland and monitoring the operation management process, and it is also difficult to achieve in-situ real-time monitoring of the environmental parameters inside a constructed wetland. This problem is particularly prominent in pilot-scale and actual engineering constructed wetlands.

[0004] Therefore, how to periodically and continuously collect water samples and substrate samples from different parts inside a constructed wetland without damaging the structure of the constructed wetland is a key problem to be solved. At the same time, how to in-situ monitor the environmental parameters inside a constructed wetland is also a problem to be solved urgently. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a device for continuous sampling and in-situ monitoring inside a constructed wetland and a use method. The device can easily achieve multiple sampling of the substrate and water quality inside a constructed wetland during operation without damaging the structure of the constructed wetland, and can also long-term in-situ monitor environmental parameters such as dissolved oxygen, temperature, salinity and pH.

[0006] The present application is realized by the following technical solutions:

[0007] The device for continuous sampling and in-situ monitoring inside the artificial wetland comprises an outer frame, one or more substrate sampling cylinders and an in-situ monitoring cylinder, the outer frame is a three-dimensional square frame, and the outer frame is composed of a grid around the frame; the substrate sampling cylinder is a square grid cylinder placed inside the outer frame, and the in-situ monitoring cylinder is placed inside the substrate sampling cylinder for water sampling and in-situ monitoring of environmental parameters, the in-situ monitoring cylinder has no bottom and has water-permeable holes on the peripheral wall, and the height of the in-situ monitoring cylinder is equal to that of the substrate sampling cylinder.

[0008] Further, the outer frame is composed of a grid around the frame, the pore size of each layer of the grid is designed according to the particle size of the substrate at different levels of the wetland, and the grid can support the external substrate and allow water to pass through smoothly, and the height of each pore size of the grid is consistent with the height of the corresponding substrate layer.

[0009] Further, the substrate sampling cylinder has a split structure in layers from top to bottom, each layer of the substrate sampling cylinder has a peripheral wall and a bottom, and the peripheral wall and the bottom are provided with a grid, the size of the grid is consistent with the particle size of the corresponding layer of substrate, and the substrate sampling cylinder for placing the in-situ monitoring cylinder has an integrated structure from top to bottom.

[0010] Further, the substrate sampling cylinder is welded with a handle at the upper part.

[0011] Further, nine substrate sampling cylinders can be arranged inside one outer frame, and the in-situ monitoring cylinder is placed inside the center substrate sampling cylinder, and the eight substrate sampling cylinders and the in-situ monitoring cylinder are filled with substrates with the same height.

[0012] Further, the substrate sampling cylinder is equal in height, and the substrate filled therein is the same as the substrate material and height of the artificial wetland.

[0013] Further, the size of the water-permeable hole on the peripheral wall of the in-situ monitoring cylinder is the same as the size of the smallest grid on the substrate sampling cylinder.

[0014] The application also provides a method for using the device, and the method specifically comprises the following steps: when the artificial wetland is constructed, the corresponding substrate is filled into the substrate sampling cylinder according to the filling substrate of the artificial wetland, the layers are bound with a ribbon, the outer frame is placed into the artificial wetland, the substrate sampling cylinder is placed inside the outer frame, the in-situ monitoring cylinder is placed into the center position of the substrate sampling cylinder without layering, and the substrate of the corresponding layer is filled between the substrate sampling cylinder and the in-situ monitoring cylinder.

[0015] Further, the sub-sampling cylinders of the upper and lower split structure are bundled together, and each layer of the sub-sampling cylinder is a cylindrical body with a bottom at the lower part and a missing upper end, and the water-permeable holes on the bottom are of the same size as the water-permeable holes on the peripheral wall.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] The device of the present application integrates water quality sampling, substrate sampling and in-situ monitoring of environmental parameters, has higher integration compared with existing devices, can be used for long-term and multiple times, does not damage the overall structure of the surrounding wetland, and does not affect the operation of the wetland. In addition, the device of the present application is simple to operate, easy to use, and can be reused. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Fig. 1 is a structural schematic diagram of the outer frame of the device of the present application;

[0019] Figure 2 Fig. 3 is a structural schematic diagram of the substrate sampling cylinder of the device of the present application;

[0020] Figure 3 Fig. 4 is a structural schematic diagram of the in-situ monitoring cylinder of the device of the present application;

[0021] Figure 4 Fig. 5 is a structural schematic diagram of the device of the present application, wherein a is a top view, b is a side view, c is an A-A sectional view, and d is a B-B sectional view; 1 is an outer frame, 2 is a substrate sampling cylinder, 3 is an in-situ monitoring cylinder, and 4 is a bundling belt. DETAILED DESCRIPTION

[0022] The technical solutions of the present application will be further explained below by means of examples in conjunction with the accompanying drawings, but the protection scope of the present application is not limited in any form by the examples.

[0023] Example 1

[0024] A device for continuous sampling and in-situ monitoring inside an artificial wetland, the device comprising an outer frame, one or more substrate sampling cylinders and an in-situ monitoring cylinder, the outer frame being a three-dimensional square frame composed of a grid on all sides; the substrate sampling cylinder is a square grid cylinder placed inside the outer frame, and the in-situ monitoring cylinder is placed inside a substrate sampling cylinder, the in-situ monitoring cylinder being bottomless and having water-permeable holes on the peripheral wall.

[0025] Example 2

[0026] The application relates to a device for continuous sampling and in-situ monitoring of an artificial wetland, which comprises an outer frame, one or more substrate sampling cylinders and an in-situ monitoring cylinder, the outer frame is a cubic frame, and the outer frame is composed of a mesh; the substrate sampling cylinder is a cubic mesh cylinder placed in the outer frame, and the in-situ monitoring cylinder is placed in one of the substrate sampling cylinders; the in-situ monitoring cylinder is bottomless and has water-permeable holes in the peripheral wall, and is used for water sampling and in-situ monitoring of environmental parameters.

[0027] The outer frame is composed of a mesh, the pore diameter of each layer of the mesh is designed according to the particle diameter of the substrate of different layers of the wetland, and the mesh can support the external substrate and allow water to pass through smoothly; the height of each pore diameter of the mesh is consistent with the height of the corresponding substrate layer.

[0028] Example 3

[0029] A device for continuous sampling and in-situ monitoring of an artificial wetland, as shown in Figures 1-4 The device comprises an outer frame 1, one or more substrate sampling cylinders 2 and an in-situ monitoring cylinder 3, the outer frame is a cubic frame, and the outer frame is composed of a mesh; the substrate sampling cylinder 2 is a cubic mesh cylinder placed in the outer frame, and the in-situ monitoring cylinder 3 is placed in one of the substrate sampling cylinders 2; the in-situ monitoring cylinder 3 is bottomless and has water-permeable holes in the peripheral wall.

[0030] The outer frame is composed of a mesh, the pore diameter of each layer of the mesh is designed according to the particle diameter of the substrate of different layers of the wetland, and the mesh can support the external substrate and allow water to pass through smoothly; the height of each pore diameter of the mesh is consistent with the height of the corresponding substrate layer.

[0031] Nine substrate sampling cylinders can be arranged in the outer frame, and one of the substrate sampling cylinders is provided with the in-situ monitoring cylinder 3, the substrate sampling cylinder 2 is an integrated structure without layers and is provided with a bottom and a peripheral wall, and the peripheral wall is provided with water-permeable holes with the same pore diameter as the particle diameter of the substrate of the same horizontal layer; the other eight substrate sampling cylinders are divided into upper, middle and lower parts and are respectively composed of three sub-sampling cylinders, the bottom and the peripheral wall of each sub-sampling cylinder are provided with meshes with the same pore diameter as the particle diameter of the substrate of the same horizontal layer; the substrate sampling cylinder is welded with a handle at the upper part; the layer height of the substrate filled in each substrate sampling cylinder is the same as the substrate material and the height of the artificial wetland.

[0032] The substrate sampling cylinder 2 is equal in height, the height of the in-situ monitoring cylinder 3 is consistent with that of the substrate sampling cylinder 2, and the size of the water-permeable holes in the peripheral wall is the same as that of the smallest mesh of the substrate sampling cylinder.

[0033] Example 4

[0034] The device described in Example 3 is used in a pilot-scale artificial wetland.

[0035] (1) Outer frame for placing the substrate sampling cylinder and supporting the substrate outside the sampling frame. The bottom surface of the outer frame is square, and the outer frame is composed of a stainless steel grid around it. The pore size of each layer of the grid is designed according to the particle size of the substrate at different levels of the wetland, which needs to ensure that it can support the external substrate and allow water to pass freely. The height of the grid is consistent with the height of the corresponding substrate layer.

[0036] The outer frame has a length, width and height of 34 cm, 34 cm and 80 cm, respectively, and a wall thickness of 3 mm. In this embodiment, the substrate of the constructed wetland is divided into three layers from top to bottom, which are coarse sand with a layer height of 20 cm and a particle size of 2-3 mm, coal cinder with a layer height of 20 cm and a particle size of 3-4 cm, and gravel with a layer height of 40 cm and a particle size of 8-10 cm. Therefore, according to the layer height of the substrate, the sampling frame is divided into three layers from top to bottom, with a grid size of 1 mm, 1 cm and 3 cm. The material of the outer frame is 304 stainless steel.

[0037] (2) Substrate sampling cylinder; for filling the substrate. In this embodiment, there are 8 substrate sampling cylinders, which are composed of three parts from top to bottom, with a bottom surface size of 10 cm x 10 cm. According to the layer height and particle size of the substrate of the pilot-scale constructed wetland, the upper layer has a height of 20 cm, a hole size of 1 mm around and at the bottom, and is used to fill coarse sand; the middle layer has a height of 20 cm, a hole size of 1 cm around and at the bottom, and is used to fill coal cinder; the lower layer has a height of 40 cm, a hole size of 3 cm around and at the bottom, and is used to fill gravel. The three parts of the substrate sampling cylinder are connected by a binding tape 4. A handle is welded on the upper part of the substrate sampling cylinder, with a height of 5 cm, which facilitates the extraction of the substrate sampling cylinder during substrate sampling. The material of the substrate sampling cylinder is 304 stainless steel. In addition, another substrate sampling cylinder has an integrated structure without layers, with a grid size consistent with that of the other 8 substrate sampling cylinders.

[0038] (3) In-situ monitoring cylinder: a small cylinder with a diameter of 6 cm, made of 304 stainless steel, with no bottom, a height of 80 cm, and a hole size of 1 mm around, and a wall thickness of 2 mm. It is used to collect water samples and monitor environmental parameters in-situ.

[0039] When the constructed wetland is constructed, the outer frame is simultaneously buried in the appropriate part of the constructed wetland. According to the need, fill each layer of the internal substrate sampling cylinder with the corresponding substrate, arrange them in a cross shape and place them in the outer frame, and then fill the substrate around the central substrate sampling cylinder with the in-situ monitoring cylinder.

[0040] The coarse sand, coal cinder and gravel are respectively filled into three sub-sampling cylinders of eight matrix sampling cylinders, and are tightly fastened by the binding belt 4. The matrix sampling cylinders are placed in the outer frame in the shape of a cross, and the upper and lower integrated structure matrix sampling cylinder is placed in the center. The in-situ monitoring cylinder is placed first, and then the matrix is filled between the in-situ monitoring cylinder and the matrix sampling cylinder. In the process of constructing the vertical flow composite constructed wetland, the sampling device is simultaneously buried, and two groups of the downflow tank and the upflow tank are placed, and the plants are planted in the upper coarse sand layer. Then the aquaculture wastewater is introduced into the upper end of the downflow tank of the constructed wetland, flows into the upflow tank through the bottom, and finally flows out from the upper part of the upflow tank. During the experimental process from the initial stage of the biofilm formation to the mature stage of the biofilm formation and then to the aging stage, the water samples in the constructed wetland are periodically extracted by using 200 mL needle tubes and fine water pipes, and the probe is deep into the small cylinder by using the YSI water quality monitoring device for monitoring the environmental parameters in-situ. When the wetland is operated for 1 month, 2 months and 3 months, four internal sampling cylinders are taken out from the downflow tank and the upflow tank respectively, and the matrix samples at different levels are taken out for subsequent analysis.

[0041] Example 5

[0042] The device described in this embodiment is an indoor simulated constructed wetland, and the structure of the device is shown in Example 3.

[0043] (1) The outer frame has a length, width and height of 19 cm, 19 cm and 60 cm respectively, and a wall thickness of 3 mm. The matrix of the constructed wetland in this embodiment is divided into three layers from top to bottom, and the layers are coarse sand with a layer height of 15 cm and a particle size of 1-2 mm, coal cinder with a layer height of 15 cm and a particle size of 2-3 cm, and zeolite with a layer height of 30 cm and a particle size of about 3-4 cm. Therefore, the outer frame is divided into three layers with a layer height of 15 cm, 15 cm and 30 cm from top to bottom, and the grid sizes are designed to be 1 mm, 0.5 cm and 1 cm. The material of the outer frame is 304 stainless steel.

[0044] (2) The matrix sampling cylinder. Eight matrix sampling cylinders are composed of three parts, i.e. upper, middle and lower parts, and the bottom size is 5 cm x 5 cm. According to the layering height and particle size of the simulated constructed wetland matrix, the upper layer has a height of 15 cm, and the hole size around the periphery and the bottom is 1 mm, which is used for filling coarse sand; the middle layer has a height of 15 cm, and the hole size around the periphery and the bottom is 0.5 cm, which is used for filling coal cinder; and the lower layer has a height of 30 cm, and the hole size around the periphery and the bottom is 1 cm, which is used for filling zeolite. The three sub-sampling cylinders are connected by the binding belt 4. The material of the matrix sampling cylinder is 304 stainless steel. In addition, one matrix sampling cylinder is an upper and lower integrated structure, and the other structures are the same as those of the eight matrix sampling cylinders.

[0045] (3) In-situ monitoring cylinder: A small cylinder with a diameter of 2.5 cm and made of 304 stainless steel is placed inside the upper and lower integrated matrix sampling cylinder. It is bottomless, 60 cm high, has 1 mm openings on all sides, and a wall thickness of 2 mm. It is used to collect water samples and in-situ monitor internal environmental parameters. It is made of stainless steel.

[0046] A 200mL syringe and a capillary tube were used to extract water samples from the constructed wetland. A YSI water quality monitoring device was used to insert a probe into a small cylinder for in-situ monitoring of environmental parameters.

[0047] Coarse sand, coal slag, and zeolite were placed in three sub-sampling tubes of eight matrix sampling tubes, secured with cable ties, and placed in a crisscross pattern within the outer sampling frame. The in-situ monitoring tube was placed within the middle matrix sampling tube. During the filling process of the simulated vertical flow composite constructed wetland, the sampling devices were simultaneously landfilled, with two sets placed in each of the descending and ascending pools. Plants were planted in the upper coarse sand layer. Aquaculture wastewater was then introduced into the upper end of the descending pool, flowing through the bottom of the ascending pool and finally out of the upper portion of the ascending pool. From the initial stage of biofilm formation to its maturity and aging, water samples were regularly drawn from the constructed wetland using a 200mL syringe and a capillary tube. In situ environmental parameters were monitored using a YSI water quality monitoring device, with the probe inserted into the central void. After one, two, and three months of operation, four internal sampling tubes were removed from the descending and ascending pools, respectively, and matrix samples from different layers were retrieved for subsequent analysis.

Claims

1. A device for continuous sampling and in-situ monitoring inside a constructed wetland, characterized in that, The device comprises an outer frame, one or more substrate sampling cylinders and an in-situ monitoring cylinder, the outer frame is a three-dimensional square frame, and the outer frame is surrounded by a grid; the substrate sampling cylinder is a square grid cylinder placed inside the outer frame, and the in-situ monitoring cylinder is placed inside the substrate sampling cylinder for water sampling and in-situ monitoring of environmental parameters, the in-situ monitoring cylinder has no bottom and has water-permeable holes on the peripheral wall and is at the same height as the substrate sampling cylinder; the pore size of each layer of the grid is designed according to the particle size of the substrate at different levels of the wetland, and the grid must be able to support the external substrate and allow water to pass through smoothly, and the height of each layer of the grid is consistent with the height of the corresponding substrate layer; The substrate sampling cylinder has a split structure in layers, each layer of the substrate sampling cylinder has a peripheral wall and a bottom, and the peripheral wall and the bottom are provided with a grid, and the size of the grid is consistent with the particle size of the corresponding layer of the substrate, and the substrate sampling cylinder for placing the in-situ monitoring cylinder has an integrated structure in layers; Nine substrate sampling cylinders can be arranged inside the outer frame, one of which is not layered and has an in-situ monitoring cylinder placed inside, and the other eight substrate sampling cylinders and the in-situ monitoring cylinder are filled with substrate of the same horizontal height environment; The substrate sampling cylinder is at the same height, and the substrate filled therein is the same as the substrate material and height filled in the constructed wetland. The size of the water-permeable hole on the peripheral wall of the in-situ monitoring cylinder is the same as the size of the smallest grid on the substrate sampling cylinder.

2. The device for continuous sampling and in-situ monitoring inside a constructed wetland according to claim 1, characterized in that, A handle is welded to the upper part of the substrate sampling cylinder.

3. The method of using the device of any one of claims 1 or 2, wherein, The method is as follows: when the constructed wetland is constructed, the corresponding substrate is filled in the substrate sampling cylinder according to the substrate filled in the constructed wetland, and the layers are tied together with a tie; first, the outer frame is placed in the constructed wetland, and then the substrate sampling cylinder is placed inside the outer frame; the in-situ monitoring cylinder is placed in the center of the non-layered substrate sampling cylinder, and the corresponding layers of substrate are filled between the substrate sampling cylinder and the in-situ monitoring cylinder; after the constructed wetland is constructed and starts to operate, the environmental parameter detection sensor probe is regularly placed in the in-situ monitoring cylinder to collect the environmental parameters of the constructed wetland in real time, including dissolved oxygen, temperature, salinity and pH, for in-situ monitoring, and water samples at different heights are regularly taken; every certain period of time, one or several substrate sampling cylinders are taken out to collect substrate samples from different substrate layers in the constructed wetland.

4. The method of using the device of claim 3, wherein, The substrate sampling cylinder has a split structure in layers, each layer of the substrate sampling cylinder has a peripheral wall and a bottom, and the peripheral wall and the bottom are provided with a grid, and the size of the grid is consistent with the particle size of the corresponding layer of the substrate, and the substrate sampling cylinder for placing the in-situ monitoring cylinder has an integrated structure in layers; Nine substrate sampling cylinders can be arranged inside the outer frame, one of which is not layered and has an in-situ monitoring cylinder placed inside, and the other eight substrate sampling cylinders and the in-situ monitoring cylinder are filled with substrate of the same horizontal height environment; The substrate sampling cylinder is at the same height, and the substrate filled therein is the same as the substrate material and height filled in the constructed wetland. The size of the water-permeable hole on the peripheral wall of the in-situ monitoring cylinder is the same as the size of the smallest grid on the substrate sampling cylinder. A handle is welded to the upper part of the substrate sampling cylinder. The method is as follows: when the constructed wetland is constructed, the corresponding substrate is filled in the substrate sampling cylinder according to the substrate filled in the constructed wetland, and the layers are tied together with a tie; first, the outer frame is placed in the constructed wetland, and then the substrate sampling cylinder is placed inside the outer frame; the in-situ monitoring cylinder is placed in the center of the non-layered substrate sampling cylinder, and the corresponding layers of substrate are filled between the substrate sampling cylinder and the in-situ monitoring cylinder; after the constructed wetland is constructed and starts to operate, the environmental parameter detection sensor probe is regularly placed in the in-situ monitoring cylinder to collect the environmental parameters of the constructed wetland in real time, including dissolved oxygen, temperature, salinity and pH, for in-situ monitoring, and water samples at different heights are regularly taken; every certain period of time, one or several substrate sampling cylinders are taken out to collect substrate samples from different substrate layers in the constructed wetland. The substrate sampling cylinder has a split structure in layers, each layer of the substrate sampling cylinder has a peripheral wall and a bottom, and the peripheral wall and the bottom are provided with a grid, and the size of the grid is consistent with the particle size of the corresponding layer of the substrate, and the substrate sampling cylinder for placing the in-situ monitoring cylinder has an integrated structure in layers;

Images