Composite artificial wetland system

Abstract

The utility model discloses a composite artificial wetland system which comprises a pretreatment tank, a water inlet channel, a composite artificial wetland treatment unit, a facultative oxidation pond, an aerobic pond and a circulating reflux pipeline, the pretreatment tank is used for pretreating inlet water; effluent of the pretreatment tank is connected with the composite constructed wetland treatment unit through the water inlet canal, and effluent of the composite constructed wetland treatment unit is connected to the facultative oxidation pond; the effluent of the facultative oxidation pond is connected to the aerobic pond, and the effluent of the aerobic pond is connected to the composite constructed wetland treatment unit through a circulating reflux pipeline, and is used for refluxing the effluent of the aerobic pond to the composite constructed wetland treatment unit when the effluent of the aerobic pond does not meet the water quality requirement. The composite artificial wetland system can further reduce the content of TN and TP in tail water of a sewage plant and reduce the concentration of the tail water; and moreover, the effects of removing ammonia nitrogen, COD, TP, TN and the like neutralized in the water body are obvious, and the effluent can reach the IV-class water standard.

Description

Technical Field

[0001] The present application belongs to the field of artificial wetlands, and specifically relates to a composite artificial wetland system. Background Art

[0002] With the continuous development of industrialization and urbanization, sewage treatment has become an important environmental protection task. Sewage treatment plants are important facilities for treating urban sewage, and the characteristics of their effluent quality have an important impact on the environment and human health. The characteristics of the effluent quality of sewage treatment plants are mainly reflected in the following aspects: 1) High suspended matter concentration: Sewage contains a large amount of suspended matter, such as organic matter, particulate matter, sediment, etc. These suspended matter will not only affect the transparency of the water body, but also cause harm to aquatic organisms, and will also affect the utilization value of water. 2) High concentrations of ammonia nitrogen and total phosphorus: Ammonia nitrogen and total phosphorus in sewage are one of the main pollutants in water bodies. High concentrations of ammonia nitrogen and total phosphorus have serious effects on aquatic organisms and aquatic ecosystems, and are likely to cause eutrophication of water bodies, leading to explosive growth of algae, and then triggering algal bloom events.

[0003] In view of the characteristics of the effluent quality of the above sewage treatment plants, artificial wetland treatment is an effective treatment method, and its necessity is mainly reflected in the following aspects: 1) Removal of suspended matter: artificial wetlands can effectively remove suspended matter in sewage through the root system of wetland plants and the filtering effect of wetland media. The root system of wetland plants can adsorb and filter particulate matter and organic matter in sewage, thereby reducing the concentration of suspended matter in the effluent of sewage treatment plants and improving water quality; 2) Removal of ammonia nitrogen and total phosphorus: wetland plants and microorganisms in artificial wetlands can absorb and degrade ammonia nitrogen and total phosphorus in sewage. The root system of wetland plants provides the absorption medium of ammonia nitrogen and total phosphorus, while the microorganisms in the wetland convert ammonia nitrogen and total phosphorus into harmless nitrogen gas and phosphate through redox reactions, thereby achieving the purpose of removing ammonia nitrogen and total phosphorus; 3) Degradation of organic matter: wetland plants and microorganisms in artificial wetlands can degrade organic matter in sewage. The root system of wetland plants provides the medium for degrading organic matter, while the microorganisms in the wetland reduce the concentration of organic matter in sewage by decomposing and transforming organic matter.

[0004] In some places, sewage treatment tail water needs to meet the quasi-Class IV discharge standard. With the currently commonly used sewage treatment process, its tail water is difficult to meet the discharge requirements because it needs to be further optimized. However, it is difficult to remove TN, TP, ammonia nitrogen and other impurities in the tail water. Generally, it is necessary to further optimize the sewage in combination with artificial wetlands so that the sewage treatment can meet the needs of urban landscape water use. At present, there is no artificial wetland treatment process and layout method for efficiently removing TP, TN and other impurities from the tail water discharged from the sewage treatment plant. Utility Model Content

[0005] The purpose of this application is to overcome the defects in the prior art and address the technical problem that the tail water discharged from sewage treatment plants is difficult to meet the discharge standard of Class IV water. Therefore, this application adopts a composite constructed wetland system to solve the above problems, and the specific technical solutions are as follows:

[0006] A composite constructed wetland system includes a pretreatment tank, an inlet channel, a composite constructed wetland treatment unit, a facultative oxidation pond, an aerobic pond, and a circulating reflux pipeline; the pretreatment tank is used for pretreating the influent; the effluent of the pretreatment tank is connected to the composite constructed wetland treatment unit through the inlet channel, and the effluent of the composite constructed wetland treatment unit is connected to the facultative oxidation pond; the effluent of the facultative oxidation pond is connected to the aerobic pond, and the effluent of the aerobic pond is connected to the composite constructed wetland treatment unit through the circulating reflux pipeline, which is used to return the effluent of the aerobic pond to the composite constructed wetland treatment unit when the effluent of the aerobic pond does not meet the water quality requirements.

[0007] The composite constructed wetland treatment unit includes a downflow subsurface flow wetland, an upflow subsurface flow wetland, and a free surface flow wetland; the effluent of the inlet channel is connected to the downflow subsurface flow wetland, the downflow subsurface flow wetland is connected to the upflow subsurface flow wetland, and the effluent of the upflow subsurface flow wetland is connected to the free surface flow wetland; the effluent of the free surface flow wetland is connected to the facultative oxidation pond.

[0008] Further, there are multiple downflow subsurface flow wetlands and multiple upflow subsurface flow wetlands, and each downflow subsurface flow wetland is connected to one upflow subsurface flow wetland.

[0009] Further, the downflow subsurface flow wetland includes an upper collecting channel, a downflow wetland filler layer, a first lower collecting main pipe, and a first lower collecting branch pipe; among them, the upper collecting channel is arranged on the upper layer of the downflow subsurface flow wetland for influent; the downflow wetland filler layer is arranged in the middle layer of the downflow subsurface flow wetland for nitrogen and phosphorus removal and sediment interception; the first lower collecting branch pipe and the first lower collecting main pipe are connected and arranged on the lower layer of the downflow subsurface flow wetland for collecting the water seeping down from the upper layer.

[0010] Further, the first lower collecting branch pipe and the first lower collecting main pipe are arranged in a "rich" character layout.

[0011] Further, the up-flow subsurface flow wetland includes an upper collecting main pipe, upper collecting branch pipes, an up-flow wetland filler layer, second lower collecting branch pipes, and a second lower collecting main pipe; wherein, the second lower collecting branch pipes and the second lower collecting main pipe are arranged in the lower layer of the up-flow subsurface flow wetland for water inlet; the up-flow wetland filler layer is arranged in the middle layer of the up-flow subsurface flow wetland for further nitrogen and phosphorus removal and sediment interception; the upper collecting main pipe is connected to the upper collecting branch pipes and is arranged in the upper layer of the up-flow subsurface flow wetland for water outlet.

[0012] Further, the upper collecting main pipe and the upper collecting branch pipes are arranged in a "rich" character layout.

[0013] Further, both the up-flow wetland filler layer and the down-flow wetland filler layer are successively composed of plain soil, bentonite waterproof blanket, backfill soil layer, non-woven fabric layer, biological filler, and wetland plants from bottom to top.

[0014] Further, the free surface flow wetland includes plants and MBBR biological filler.

[0015] Further, the pretreatment tank is a grit chamber with a filtering function, and the filtering grilles are arranged alternately and staggeredly.

[0016] Further, a slope is set at the bottom of the pretreatment tank so that the elevation of the water inlet is 5 - 10 cm lower than the elevation of the water outlet.

[0017] Compared with the prior art, the beneficial effects of the present application are as follows:

[0018] The composite constructed wetland system of the present utility model can further reduce the contents of TN and TP in the tail water of the sewage treatment plant and lower their concentrations; and it has remarkable effects in removing ammonia nitrogen, COD, TP, TN, etc. in the water body, and the effluent can reach the Class IV water standard. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It shows the general layout plan of the composite constructed wetland system adopted in this embodiment.

[0020] Figure 2 It shows the plan view of the pretreatment tank 1 in this embodiment.

[0021] Figure 3 It shows the sectional view of the pretreatment tank 1 in this embodiment.

[0022] Figure 4 It shows the sectional view of the composite constructed wetland treatment unit 3 in this embodiment.

[0023] Figure 5 It shows the layout plan of the pipelines in the lower layer of the constructed wetland.

[0024] Figure 6 Represents the upper pipe layout diagram of the artificial wetland plane.

[0025] Figure 7 A cross-sectional view showing an upstream wetland filler layer 313 and a downstream wetland filler layer 323 .

[0026] Figure 8 represents a surface free-flow wetland;

[0027] Among them, there are a pretreatment tank 1, an inlet channel 2, a composite artificial wetland treatment unit 3, a facultative oxidation pond 4, an aerobic pond 5, a circulation reflow pipe 6, an upstream submerged flow wetland 31, a downstream submerged flow wetland 32, a free surface flow wetland 33, a first lower layer water collecting main pipe 321, a first lower layer water collecting branch pipe 322, a downstream wetland filler layer 323, an upper layer water collecting channel 324, an upper layer water collecting main pipe 311, an upper layer water collecting branch pipe 312, an upstream wetland filler layer 313, a second lower layer water collecting branch pipe 314, and a second lower layer water collecting main pipe 315. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below according to the accompanying drawings and preferred embodiments, and the purpose and effect of the present invention will become more clear. The present invention will be further described in detail below in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] like Figure 1 As shown, the composite artificial wetland system used in this embodiment includes a pretreatment tank 1, an inlet channel 2, a composite artificial wetland treatment unit 3, a facultative oxidation pond 4, an aerobic pond 5 and a circulation return pipe 6. The inlet water first passes through the pretreatment tank 1, the effluent of the pretreatment tank 1 is connected to the composite artificial wetland treatment unit 3 through the inlet channel 2, the effluent of the composite artificial wetland treatment unit 3 is connected to the facultative oxidation pond 4, the effluent of the facultative oxidation pond 4 is connected to the aerobic pond 5, and the effluent of the aerobic pond 5 is directly discharged if it meets the water quality requirements, and if it still does not meet the effluent water quality requirements, it is returned to the composite artificial wetland treatment unit 3 through the circulation return pipe 6.

[0030] like Figure 2 As shown, the pretreatment tank 1 of this embodiment is a sand settling tank with a filtering function, and a filtering grid is arranged in the sand settling tank. Figure 3 As shown, the filter grilles in the pretreatment tank 1 are arranged alternately and staggered, a certain slope is set at the bottom of the sand settling tank, and the inlet water level is 5 to 10 cm lower than the outlet water level.

[0031] like Figure 1As shown in the figure, the composite constructed wetland treatment unit 3 of this embodiment includes an up-flow subsurface flow wetland 31, a down-flow subsurface flow wetland 32, and a free surface flow wetland 33. Among them, there are multiple down-flow subsurface flow wetlands 32 and up-flow subsurface flow wetlands 31. The effluent of the influent channel 2 is connected to multiple down-flow subsurface flow wetlands 32, the effluent of each down-flow subsurface flow wetland 32 is connected to an up-flow subsurface flow wetland 31, and the effluent of the up-flow subsurface flow wetland 31 is connected to the free surface flow wetland 33; the effluent of the free surface flow wetland 33 is connected to the facultative oxidation pond 4.

[0032] As Figure 4 shown, the down-flow subsurface flow wetland 32 of this embodiment includes an upper collecting channel 324, a down-flow wetland filler layer 323, a first lower collecting main pipe 321, and a first lower collecting branch pipe 322. Among them, the upper collecting channel 324 is arranged in the upper layer of the down-flow subsurface flow wetland 32 for influent; the down-flow wetland filler layer 323 is arranged in the middle layer of the down-flow subsurface flow wetland 32 for nitrogen and phosphorus removal and sediment interception; the first lower collecting branch pipe 322 and the first lower collecting main pipe 321 are connected and arranged in the lower layer of the down-flow subsurface flow wetland for collecting the water seeping down from the upper layer; and as Figure 5 shown, the first lower collecting branch pipe 322 and the first lower collecting main pipe 321 are arranged in a "丰" shape.

[0033] The up-flow subsurface flow wetland 31 of this embodiment includes an upper collecting main pipe 311, an upper collecting branch pipe 312, an up-flow wetland filler layer 313, a second lower collecting branch pipe 314, and a second lower collecting main pipe 315. Among them, similar to the down-flow subsurface flow wetland 32, as Figure 5 shown, the second lower collecting branch pipe 314 and the second lower collecting main pipe 315 are arranged in the lower layer of the up-flow subsurface flow wetland 31 for influent; the up-flow wetland filler layer 313 is arranged in the middle layer of the up-flow subsurface flow wetland 31 for further nitrogen and phosphorus removal and sediment interception; as Figure 6 shown, the upper collecting main pipe 311 is connected to the upper collecting branch pipe 312 and arranged in the upper layer of the up-flow subsurface flow wetland 31 for effluent; the upper collecting main pipe 311 and the upper collecting branch pipe 312 are arranged in a "丰" shape.

[0034] As Figure 7 shown, the up-flow wetland filler layer 313 and the down-flow wetland filler layer 323 of this embodiment are composed of plain soil, bentonite waterproof blanket, backfill soil layer, non-woven fabric layer, biological filler, and wetland plants from bottom to top. Among them, the plain soil needs to be tamped, and the compactness N > 15;

[0035] In this embodiment, the thickness of the bentonite waterproof blanket is 6mm, the thickness of the backfill soil layer is 300mm, and the density N>15; the biological filler includes activated carbon with a particle size of 8-15mm, fine gravel of 15-20mm and coarse gravel of 20-40mm, the activated carbon is used for adsorption and biodegradation, denitrification and phosphorus removal; the fine gravel is quartz sand, which is used to intercept sediment and adsorption; the coarse gravel is used to intercept sediment. The thickness is set according to the actual situation, but generally coarse gravel < activated carbon < fine gravel.

[0036] like Figure 8 As shown, the free surface flow wetland 33 of this embodiment includes plants and MBBR biological fillers.

[0037] Facultative oxidation pond 4 is the most common pond type in urban sewage stabilization ponds. There are three areas in facultative ponds: the surface aerobic zone, where aerobic bacteria and algae coexist and have the characteristics of aerobic ponds; the bottom anaerobic zone, where solid impurities accumulated in this area are fully decomposed by anaerobic bacteria; the middle part is the transition zone between the aerobic zone and the anaerobic zone, namely the facultative zone, where facultative bacteria that can play two roles exist and decompose organic matter through facultative bacteria.

[0038] Aerobic pond 5 is a type of stabilization pond. Aerobic ponds completely rely on photosynthesis for oxygen supply. The pond is shallow, with high dissolved oxygen, symbiosis of bacteria and algae, and aerobic reactions. It can be used for denitrification, conversion and removal of dissolved organic matter, and can also be used for deep treatment of secondary biological treatment effluent.

[0039] The operating principle of the composite artificial wetland system used in this embodiment is as follows:

[0040] The incoming water first enters the pretreatment tank 1, and then goes along the inlet channel 2. An outlet hole is set on the upper line of the inlet channel. The incoming water enters the downstream subsurface wetland 32 from the outlet hole, and enters the upstream subsurface wetland 31 through layer-by-layer filtration in the downstream subsurface wetland 32. The outlet water of the upstream subsurface wetland 31 enters the free surface flow wetland 33, and the free surface wetland enters the facultative oxidation pond 4. The outlet water of the facultative oxidation pond 4 enters the aerobic pond 5. When the water quality entering the aerobic pond meets the discharge requirements, it is directly discharged. Otherwise, the water body is returned to the pretreatment tank 1 through the circulating return pipe 6 for circulation treatment again.

[0041] Those skilled in the art can understand that the above are only preferred examples of the utility model and are not intended to limit the utility model. Although the utility model is described in detail with reference to the above examples, those skilled in the art can still modify the technical solutions recorded in the above examples or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A composite artificial wetland system, characterized in that: It includes a pretreatment pond, an inlet channel, a composite constructed wetland treatment unit, a facultative oxidation pond, an aerobic pond, and a circulation and reflux pipeline; the pretreatment pond is used for pretreating the influent water; the effluent of the pretreatment pond is connected to the composite constructed wetland treatment unit through the inlet channel, and the effluent of the composite constructed wetland treatment unit is connected to the facultative oxidation pond; the effluent of the facultative oxidation pond is connected to the aerobic pond, and the effluent of the aerobic pond is connected to the composite constructed wetland treatment unit through the circulation and reflux pipeline, which is used to reflux the effluent of the aerobic pond to the composite constructed wetland treatment unit when the effluent of the aerobic pond does not meet the water quality requirements. The composite constructed wetland treatment unit includes a downward-flow subsurface flow wetland, an upward-flow subsurface flow wetland, and a free surface flow wetland. The effluent of the inlet channel is connected to the downward-flow subsurface flow wetland, the downward-flow subsurface flow wetland is connected to the upward-flow subsurface flow wetland, and the effluent of the upward-flow subsurface flow wetland is connected to the free surface flow wetland; the effluent of the free surface flow wetland is connected to the facultative oxidation pond.

2. The composite artificial wetland system according to claim 1, characterized in that: There are multiple downward-flow subsurface flow wetlands and multiple upward-flow subsurface flow wetlands, and each downward-flow subsurface flow wetland is connected to one upward-flow subsurface flow wetland.

3. The composite artificial wetland system according to claim 1, characterized in that: The downward-flow subsurface flow wetland includes an upper water collection channel, a downward-flow wetland filler layer, a first lower water collection main pipe, and a first lower water collection branch pipe; among them, the upper water collection channel is arranged on the upper layer of the downward-flow subsurface flow wetland for influent water; the downward-flow wetland filler layer is arranged on the middle layer of the downward-flow subsurface flow wetland for nitrogen and phosphorus removal and sediment interception; the first lower water collection branch pipe is connected to the first lower water collection main pipe and is arranged on the lower layer of the downward-flow subsurface flow wetland for collecting the water seeping from the upper layer.

4. The composite artificial wetland system according to claim 3, characterized in that: The first lower water collection branch pipe and the first lower water collection main pipe are arranged in a "丰" shape.

5. The composite artificial wetland system according to claim 3, characterized in that: The upward-flow subsurface flow wetland includes an upper water collection main pipe, an upper water collection branch pipe, an upward-flow wetland filler layer, a second lower water collection branch pipe, and a second lower water collection main pipe; among them, the second lower water collection branch pipe and the second lower water collection main pipe are arranged on the lower layer of the upward-flow subsurface flow wetland for influent water; the upward-flow wetland filler layer is arranged on the middle layer of the upward-flow subsurface flow wetland for further nitrogen and phosphorus removal and sediment interception; the upper water collection main pipe is connected to the upper water collection branch pipe and is arranged on the upper layer of the upward-flow subsurface flow wetland for effluent water.

6. The composite artificial wetland system according to claim 5, characterized in that: The upper water collection main pipe and the upper water collection branch pipe are arranged in a "丰" shape.

7. The composite artificial wetland system according to claim 5, characterized in that: Both the upward-flow wetland filler layer and the downward-flow wetland filler layer are successively composed of plain soil, bentonite waterproof blanket, backfill soil layer, non-woven fabric layer, biological filler, and wetland plants from bottom to top.

8. The composite artificial wetland system according to claim 6, characterized in that: The free surface flow wetland includes plants and MBBR biological filler.

9. The composite artificial wetland system according to claim 6, characterized in that: The pretreatment pond is a grit chamber with a filtering function, and the filter grilles are arranged alternately and staggeredly.

10. The composite artificial wetland system according to claim 9, characterized in that: A slope is set at the bottom of the pretreatment pond so that the elevation of the influent water level is 5 - 10 cm lower than the elevation of the effluent water level.

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