River in-situ enhanced nitrogen removal ecological capacity expansion device

Abstract

The invention provides a river in-situ enhanced nitrogen removal ecological capacity expansion device, and belongs to the field of river in-situ purification, the river in-situ enhanced nitrogen removal ecological capacity expansion device comprises an outer frame, a biological blanket, a biological filler, submerged plants and emergent aquatic plants, the upper end of the outer frame is provided with a baffle, the bottom of the outer frame is provided with fixing feet and a gravity caisson, and the gravity caisson is connected with the fixing feet through cables; the gravity caisson is arranged in the outer frame, river sand is filled in the gravity caisson, the biological blanket comprises an aerobic biological blanket arranged above the outer frame and an anaerobic biological blanket arranged at the bottom of the outer frame, the anaerobic biological blanket is arranged in the bottom mud, the biological filler is arranged between the aerobic biological blanket and the anaerobic biological blanket, the biological filler comprises braid type biological ropes and multi-surface hollow filler balls, and the braid type biological ropes and the multi-surface hollow filler balls are arranged in the outer frame. The multi-surface hollow filler is provided with a plurality of braided biological ropes which are connected in series, emergent aquatic plants are planted above the aerobic biological blanket, and submerged plants are planted on the anaerobic biological blanket. The device is low in manufacturing cost and high in stability during use, and can efficiently perform denitrification treatment on water pollution of rivers.

Description

Technical Field

[0001] The present invention belongs to the field of in-situ river purification, and in particular relates to an in-situ enhanced denitrification ecological capacity expansion device for rivers. Background Art

[0002] According to relevant statistics, among the 469 nationally controlled sections of the ten major river systems in my country, 13.7% have water quality levels below Class V. The deteriorating water environment caused by severe pollution in urban rivers not only impacts the normal development of cities but also poses a serious threat to the health of urban residents and the ecological security of cities. Furthermore, reducing total nitrogen in rivers entering the sea is a key goal of the comprehensive management of key national sea areas and a crucial measure for continuously improving the environmental quality of coastal waters. River management and restoration is a complex undertaking, involving multiple disciplines such as water conservancy, environment, and ecology. The restoration process is influenced by numerous factors, including river flow, pollutant composition and concentration, and environmental conditions. Each management and restoration technique has a specific application range. In practical projects, comprehensive consideration and rational allocation are necessary to achieve river management and restoration. For severely polluted rivers, a combination of physical and chemical methods is needed to improve water quality, followed by biological purification and restoration of the ecosystem, ultimately achieving river management and restoration.

[0003] In the existing technology, on the one hand: the biological effect is not fully utilized, and the role of physical interception and filtration is ignored. The physical, chemical and biological effects are not effectively combined to form an integrated device, and the materials used are mostly artificially processed materials. For example, the ecological floating islands are mostly made of fiber-reinforced plastics, stainless steel plus expanded polystyrene, special expanded polystyrene plus special synthetic resins, salted ethylene synthetic resins and other materials, which will increase the risk of microplastic pollution in water bodies and the cost is relatively high; on the other hand: insufficient adaptability to dynamic hydrological conditions (such as sluice gates and dams controlling river sections, seasonal flow rate fluctuations), resulting in poor stability of the device; lack of precise control mechanism of nitrogen form conversion pathways, it is difficult to cope with complex pollution loads (such as fluctuations in the ratio of ammonia nitrogen to nitrate nitrogen); insufficient ecosystem synergy, and failure to fully utilize the multi-level interaction of plants, microorganisms and substrates to improve denitrification efficiency. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a river in-situ enhanced denitrification ecological expansion device to solve the technical problems of the prior art in-situ denitrification technology of rivers, such as long start-up cycle, unfriendly environment, high cost, poor stability and low denitrification efficiency.

[0005] To achieve the above-mentioned objectives and other related objectives, the present invention provides an in-situ enhanced denitrification ecological expansion device for a river, comprising: an outer frame, a bio-mat, a bio-filler, submerged plants and emergent plants, wherein the outer frame is a three-dimensional frame, the bio-mat comprises an aerobic bio-mat arranged above the outer frame and an anaerobic bio-mat arranged at the bottom of the outer frame, and the anaerobic bio-mat is arranged in the riverbed mud, the bio-filler is arranged between the aerobic bio-mat and the anaerobic bio-mat, the bio-filler comprises a braided bio-rope and a multi-faceted hollow filler ball, and a plurality of the multi-faceted hollow fillers are arranged in series on the braided bio-rope, the emergent plants are planted above the aerobic bio-mat, and the submerged plants are planted on the anaerobic bio-mat.

[0006] In this way, the outer frame is arranged on the upper and lower biological blankets, and a number of biological fillers are arranged between the biological blankets. The whole can intercept water pollutants, increase the hydraulic retention time without affecting flood discharge, and promote the adsorption and conversion of total nitrogen in the water by plants and microorganisms; the microorganisms in the aerobic biological blanket can remove ammonia nitrogen in the water through nitrification, the complex microorganisms attached to the biological fillers can remove total nitrogen in the water through nitrification and denitrification, and the microorganisms in the anaerobic biological blanket can remove total nitrogen in the water through denitrification; emergent plants and submerged plants have a good adsorption and conversion effect on nitrogen elements in the water; the biological filler adopts a braided biological rope connected in series with multi-faceted hollow ball fillers, which can increase the specific surface area and resistance of the combined filler and reduce the loss of microorganisms with water flow.

[0007] Optionally, the outer frame is made of poplar clones, and one side of the bio-mat has a baffle mounted on the outer frame. The bottom of the outer frame is equipped with fixed feet and a gravity member inserted into the riverbed mud. The gravity member and the fixed feet are connected by a cable. Poplar clones, which have a large number of micropores and mesopores in their cell wall pore structure, facilitate the adsorption of pollutants. The baffle prevents the loss of microorganisms attached to the bio-mat. The gravity member is connected to the fixed feet via a flexible nylon cable, allowing the outer frame to swing slightly with the water flow, avoiding structural damage caused by the rigid connection.

[0008] Optionally, the aerobic bio-mat is a coconut fiber mat, laid above and close to the water surface, with porous ceramsite filler embedded inside. This allows various grass seeds to pass through the mesh and grow smoothly. The porous and fibrous material provides a good growth and attachment site for aerobic microorganisms, and the porous ceramsite filler enhances ammonia nitrogen adsorption and nitrification reactions.

[0009] Optionally, the anaerobic biological blanket is a coconut fiber blanket, which is laid in the riverbed mud to create an anaerobic environment for anaerobic microorganisms to attach, and a slow-release carbon source module is laid on the bottom of the anaerobic biological blanket to provide a continuous carbon source for denitrification.

[0010] Optionally, the emergent plants are planted on the aerobic bio-blanket, and the emergent plants are plants that absorb nitrogen strongly, including reeds, water lilies, yellow calamus, cattails, etc. These emergent plants facilitate nitrogen absorption.

[0011] Optionally, the submerged plants are planted on the anaerobic bio-mat, and the submerged plants are plants that absorb nitrogen strongly, including foxtail algae, black algae, black algae verticillata, hornwort, and Vallisneria. These submerged plants facilitate nitrogen absorption.

[0012] Optionally, aerobic heterotrophic nitrifying bacteria are attached to the aerobic biological blanket.

[0013] Optionally, anaerobic autotrophic denitrifying bacteria are attached to the anaerobic biological blanket.

[0014] Optionally, composite denitrifying bacteria are attached to the biological filler, and the biological filler further comprises braided biological ropes and modified volcanic rock particles. The modified volcanic rock particles contain iron oxides that can promote nitrite accumulation through chemical catalysis and shorten the nitrification path.

[0015] Optionally, the slow-release carbon source module is a starch-based slow-release ball wrapped in bamboo charcoal, which provides a continuous carbon source for denitrification, and the carbon-nitrogen ratio (C / N) is maintained at 4-6.

[0016] The beneficial effects of the present invention are: This invention offers low manufacturing costs, high stability during use, and the ability to efficiently denitrify polluted river water. Through a plant-microbe-filler material / signal interaction network, it forms a self-reinforcing denitrification system, achieving the unification of structural stability, functional flexibility, and ecological sustainability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0018] Figure 2 Shown is a schematic diagram of the outer frame structure of the present invention. DETAILED DESCRIPTION

[0019] The following describes the implementation of the present invention through specific embodiments. People skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0020] See also Figures 1 to 2. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Therefore, they have no substantive technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0021] like Figure 1-Figure 2 As shown, a river in-situ enhanced denitrification ecological expansion device includes: an outer frame 1, a bio-mat 3, a combined biological filler 8 with attached microorganisms, submerged plants 6, and emergent plants 7. The outer frame 1 is composed of a three-dimensional frame made of poplar clone wood. The cell wall pore structure of this type of wood contains a large number of micropores and mesopores, which facilitate the adsorption of pollutants. The bottom of the outer frame 1 is provided with fixing feet 5 for facilitating insertion into the riverbed mud to fix the outer frame 1. The upper end of the outer frame 1 is riveted with a baffle 2 perpendicular to the water flow direction. The baffle 2 is located on one side of the bio-mat 3 and can be used to prevent the loss of microorganisms attached to the bio-mat 3. A gravity piece is also provided at the bottom of the outer frame 1. The gravity piece is connected to the fixed foot 5 through a flexible nylon cable. The gravity piece is sunk to the bottom of the river channel. In this way, the entire device can swing slightly with the water flow (swing angle ≤ 15°), avoiding structural damage caused by the rigid connection between the outer frame and the gravity piece under the impact of the water flow.

[0022] Specifically, the gravity member can be a gravity caisson, and the interior of the gravity caisson is filled with river sand or stones. The use of river sand or stones is more convenient in obtaining and transporting materials and has low cost.

[0023] The bio-blanket 3 includes an aerobic bio-blanket 301 and an anaerobic bio-blanket 302 . The aerobic bio-blanket 301 is fixedly laid on the upper side of the outer frame 1 , and the anaerobic bio-blanket 302 is fixedly laid on the lower end of the outer frame 1 and is located in the silt at the bottom of the river channel.

[0024] Aerobic Bio-Blanket 301 is made of coconut shreds and protective nets of different specifications and strengths, with seeds of various emergent plants placed inside. The protective nets are set up with 5 layers, and the pore size of the protective nets decreases from 20mm to 5mm from the outside to the inside. A composite filtration system is formed between the coconut shreds and the protective nets, and the interwoven density of coconut shreds reaches 1200-1500 strands / dm 2This allows various grass seeds to pass smoothly through the mesh during germination. The porous and fibrous material also provides an ideal habitat for aerobic microorganisms, which are heterotrophic aerobic nitrifying bacteria. These microorganisms are commercially available granular nitrifying bacteria (Candidatus Nitrotoga arctica, with a viable count of ≥40%), and are embedded in the aerobic bio-blanket. Aerobic bio-blanket 301 is positioned near the water surface, topped with emergent aquatic plants with strong nitrogen absorption and conversion capabilities, such as reeds, water lilies, yellow irises, and cattails. These plants not only fix nitrogen but also provide ornamental value.

[0025] Specifically, coconut fiber blankets comply with the GB / T 35602-2017 Plant Fiber Blankets for Ecological Restoration standard.

[0026] Specifically, the roots of emergent plants (reeds) secrete flavonoids (such as rutin, HPLC (high performance liquid chromatography) detection concentration of 1.2 μg / mL), which stimulate the activity of ACC deaminase (1-aminocyclopropane-1-carboxylic acid deaminase) in the biofilm by 27%, promoting biofilm renewal.

[0027] Specifically, the size of the outer frame 1 is determined by the size of the river channel, and the height is 0.1~0.2m higher than the water depth. The thickness of the aerobic bio-blanket 301 can also be increased to 15~20cm, and porous ceramsite fillers can be embedded inside. The particle size of the porous ceramsite fillers is 5~8mm, and the specific surface area is greater than 300m 2 / g, can enhance ammonia nitrogen adsorption and nitrification reaction.

[0028] Anaerobic Bio-Blanket 302 is made from the same materials as Aerobic Bio-Blanket 301, made from coconut shreds and mesh of varying specifications and strengths. When laid within riverbed mud, it creates an anoxic environment conducive to the growth of anaerobic microorganisms. The attached anaerobic microorganisms are anaerobic autotrophic denitrifying bacteria, using commercially available granular denitrifying bacteria (Thiobacillus denitrificans, with an effective viable count of ≥35%), which are then embedded within the bio-blanket. A slow-release carbon source module is also required at the bottom of the anaerobic bio-blanket to provide a continuous carbon source for the denitrification reaction, maintaining a carbon-to-nitrogen ratio (C / N) of 4-6. The anaerobic bio-blanket, nestled within the riverbed mud, can be cultivated with submerged plants that are highly efficient in nitrogen absorption and conversion, including foxtail algae, hydrilla, hydrilla verticillata, hornwort, and Vallisneria.

[0029] Specifically, the slow-release carbon source module can be bamboo charcoal, including starch-based slow-release balls. The kinetic model of starch-based slow-release balls is as follows: cross-linked carboxymethyl starch is used as the matrix (cross-linking degree 15%), and bamboo charcoal powder (particle size 200 mesh) is wrapped to form a core-shell structure (shell thickness 0.5 mm). Carbon release in water at 25°C conforms to the first-order kinetic equation (k = 0.12 d-1 ), the carbon-nitrogen ratio (C / N) was stabilized at 4.8±0.3 through release rate feedback regulation, and the denitrification efficiency reached 93.5% (batch experiment).

[0030] The biological filler 5 is a combined biological filler, which adopts a braided biological rope to connect multiple multi-faceted hollow spherical fillers in series, which can increase the specific surface area and resistance capacity of the combined biological filler 5 and reduce the loss of microorganisms with water flow.

[0031] Biofiller 5 can also be made by connecting multiple modified volcanic rock particles in a braided biorope. The iron oxides loaded on the modified volcanic rock particles can promote the accumulation of nitrite through chemical catalysis and shorten the nitrification path. FeCl3 hydrothermal method was used to load goethite (α-FeHO2) on the surface of volcanic rock. XPS (X-ray photoelectron spectroscopy) analysis showed that Fe 2+ / Fe 3+ The molar ratio is 1:2.4, and at pH 7.0, it can promote the NH 4+ →NO 2- path, the nitrification rate increased by 2.1 times.

[0032] The Fenton-like reaction is an oxidation process similar to the classic Fenton reaction. It uses a catalyst to activate hydrogen peroxide (H₂O₂) to produce highly oxidizing hydroxyl radicals (·OH), which are used to degrade recalcitrant organic pollutants. Compared to the classic Fenton reaction (which typically requires strongly acidic conditions), the Fenton-like reaction can occur over a wider pH range and can use a variety of transition metal ions (such as Cu²⁺, Co²⁺, and Mn²⁺) as catalysts.

[0033] The microorganisms attached to the biological filler 5 are composite denitrifying bacteria. The biological filler is immersed in the composite bacterial solution. After the bacteria are attached to the biological filler, the two ends of the biological filler are fixed between the aerobic biological blanket and the anaerobic biological blanket by means of easy-pull bags or the like.

[0034] Specifically, the composite denitrifying bacteria include Bacillus subtilis and Acinetobacter johnsonii. Specifically, the bio-rope material in the bio-filler 5 has a diameter of 8 cm and a length greater than the height of the outer frame by 0.2 m; the size of the multi-faceted hollow filler ball is a diameter of 15 cm.

[0035] Working principle: The device of the present invention can intercept water pollutants to a certain extent. The biological blanket adopts 5 layers of gradient protection net (the aperture decreases from 20mm to 5mm from the outside to the inside), forming a composite filtration system. The density of coconut fiber interweaving reaches 1200-1500 pieces / dm 2 , can intercept >90% of suspended solids (SS (suspended solids) particle size >50μm), the multi-faceted hollow ball filler forms a fluidized bed, which makes the water flow produce a Z-shaped path (tortuousness coefficient 2.3), increases the hydraulic retention time without affecting flood discharge, and promotes the adsorption and conversion of total nitrogen in the water by plants and microorganisms; the microorganisms in the aerobic biological blanket can remove ammonia nitrogen in the water through nitrification, the composite microorganisms attached to the combined biological filler can remove total nitrogen in the water through nitrification and denitrification, and the microorganisms in the anaerobic biological blanket can remove total nitrogen in the water through denitrification; the emergent plants and submerged plants have a good adsorption and conversion effect on nitrogen elements in the water.

[0036] The entire device can stably perform the in-situ removal of total nitrogen when the water flow rate is less than 0.08 m / s, with a maximum removal rate of about 40%. Specific embodiment: A river in Rudong County, Nantong City, Jiangsu Province was selected. According to the flow rate and channel size of the river, 10 sets of devices were set up in a 334 arrangement. The estimated water volume of the river to be treated is 20 m wide × 25 m long × 2.5-3 m deep = 1500 m 3 On the first day, the device was deployed in the river's test area, located near a sluice gate. The river continuously receives inflows of external pollution sources, including domestic sewage. The water volume and quality upstream of the device fluctuated significantly, and some water backflowed through the sluice gate after passing through the device. On the second day, total nitrogen, nitrate nitrogen, and ammonia nitrogen were monitored upstream and at the device. The monitoring period lasted 10 days.

[0038] Based on the available monitoring data, the changing trends of total nitrogen, nitrate nitrogen, and ammonia nitrogen upstream and at the device were analyzed. Before the device was deployed, the total nitrogen concentration in the test area was 6.6 mg / L. 22 hours after deployment, monitoring showed that the total nitrogen concentration at the device had dropped to 5.14 mg / L, with a removal rate of 22%. Under conditions of high total nitrogen pollution loads, the test area showed a significant "peak-shaving" effect on total nitrogen, with a total nitrogen removal rate of 32.6%. The test area was able to continuously and effectively reduce the total nitrogen load in the water during the trial period, with total nitrogen levels in the test area consistently lower than those in the upstream water. The device continued to operate effectively in a complex and changing environment, providing a degree of protection against adverse external factors.

[0039] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A river in-situ enhanced denitrification ecological expansion device, characterized in that: include: An outer frame, a bio-mat, a bio-filler, submerged plants and emergent plants, wherein the outer frame is a three-dimensional frame, the bio-mat comprises an aerobic bio-mat arranged above the outer frame and an anaerobic bio-mat arranged at the bottom of the outer frame, and the anaerobic bio-mat is arranged in the riverbed mud, the bio-filler is arranged between the aerobic bio-mat and the anaerobic bio-mat, the bio-filler comprises a braided bio-rope and multi-faceted hollow filler balls, a plurality of multi-faceted hollow filler balls are arranged in series on the braided bio-rope, the emergent plants are planted on the aerobic bio-mat, and the submerged plants are planted on the anaerobic bio-mat.

2. The river in-situ enhanced denitrification ecological expansion device according to claim 1, characterized in that: The outer frame is made of poplar clones. One side of the bio-mat has a baffle mounted on the outer frame. The bottom of the outer frame is provided with fixed feet and a gravity member inserted into the riverbed mud. The gravity member and the fixed feet are connected by a cable.

3. The river in-situ enhanced denitrification ecological expansion device according to claim 1, characterized in that: The aerobic biological blanket is a coconut fiber blanket, which is laid above and close to the water surface and has porous ceramsite fillers embedded in it.

4. The in-situ enhanced denitrification and ecological expansion device for rivers according to claim 1, characterized in that: The anaerobic biological blanket is a coconut fiber blanket, which is laid in the riverbed mud to create an anaerobic environment for anaerobic microorganisms to attach. A slow-release carbon source module is also laid on the bottom of the anaerobic biological blanket.

5. The river in-situ enhanced denitrification ecological expansion device according to claim 3 is characterized by: The emergent plants are planted on the aerobic biological blanket. The emergent plants are plants that have strong nitrogen absorption, including reeds, water lilies, yellow calamus, and cattails.

6. The river in-situ enhanced denitrification ecological expansion device according to claim 4, characterized in that: The submerged plants are planted on the anaerobic biological blanket. The submerged plants are plants that have strong nitrogen absorption, including foxtail algae, black algae, black algae with leaves, hornwort, and Vallisneria.

7. The river in-situ enhanced denitrification ecological capacity expansion device according to claim 3, characterized in that: Aerobic heterotrophic nitrifying bacteria are attached to the aerobic biological blanket.

8. The river in-situ enhanced denitrification ecological capacity expansion device according to claim 4, characterized in that: Anaerobic autotrophic denitrifying bacteria are attached to the anaerobic biological blanket.

9. The river in-situ enhanced denitrification ecological capacity expansion device according to claim 1, characterized in that: Composite denitrification bacteria are attached to the biological filler, and the biological filler also includes braided biological ropes and modified volcanic rock particles.

10. The river in-situ enhanced denitrification ecological capacity expansion device according to claim 4, characterized in that: The slow-release carbon source module is a starch-based slow-release ball wrapped in bamboo charcoal, which provides a continuous carbon source for denitrification, and the carbon-nitrogen ratio (C / N) is maintained at 4-6.

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