Method for rapidly restoring the aerobic state of sediment and simultaneously removing carbon, nitrogen and phosphorus from sediment

Abstract

The present invention discloses a method for rapidly restoring the aerobic state of bottom mud and simultaneously removing carbon, nitrogen and phosphorus from the bottom mud, belonging to the technical field of sludge treatment. The method comprises the following steps: (1) changing the suspended state of bottom mud in a natural water body by oscillating the bottom mud to obtain suspended bottom mud; (2) forming an oxygen-rich or oxygen-supersaturated state in the water body by photosynthesis of plants in the natural water body to obtain an oxygen-rich water body; (3) the suspended bottom mud is converted into an aerobic state by an oxidation reaction in the oxygen-rich water body, thereby reducing the content of carbon, nitrogen and phosphorus. The method of the present invention does not require the addition of any chemical or biological agents to the water body, and will not cause secondary environmental and ecological problems. At the same time, the method can be used to increase the output of aquatic products such as fish, shrimp and snails, as well as other aquatic plants with economic value, thereby generating good economic value and ecological environmental benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of sludge treatment, in particular to a method for rapidly restoring the aerobic state of bottom sludge and simultaneously removing carbon, nitrogen and phosphorus from the bottom sludge. Background Art

[0002] Natural water bodies such as rivers, lakes, and reservoirs are becoming increasingly silted due to prolonged rainfall and other factors. This siltation not only reduces the water's capacity but also causes a dramatic exchange of particulate and dissolved pollutants. Internal pollution has become a major constraint on improving the environmental quality and biodiversity of natural water bodies. While researchers have developed a range of physical, chemical, and biological remediation technologies for various polluted water bodies, significant research is still needed to address internal pollutants.

[0003] Currently, classic technologies for treating endogenous pollutants fall into two main categories. The first is ecological dredging: preliminary investigations determine the specific scope and methods of dredging, and the cleared sludge is then treated or recycled based on the actual situation. The second is phytoremediation: planting indigenous or other highly tolerant submerged plants, which absorb endogenous pollutants and harvesting them to reduce biogenic elements such as carbon, nitrogen, and phosphorus in the sediment. Both methods have significant advantages. However, they also have various shortcomings. For example, dredging is costly, prone to secondary pollution, and reduces the buffering capacity of natural water bodies. Phytoremediation is slow, labor-intensive, and limited in its applicability, resulting in a limited number of ecosystem species. Therefore, there is an urgent need to develop a new and widely applicable ecological remediation technology for endogenous pollution.

[0004] When natural water bodies are polluted, they are prone to eutrophication. Afterwards, the water sediments will gradually be in an oxygen-deficient and anaerobic environment, showing reducing properties. The proliferation of sulfate-reducing bacteria and iron-manganese reducing bacteria makes the bottom mud and water bodies appear black and smelly. Therefore, restoring the aerobic state of surface sediments is the key to achieving the reduction of endogenous pollutants. At present, plant photosynthesis or aeration is often used to restore the oxidation conditions of water bodies. Chinese patent CN102603110A discloses a method for repairing heavily polluted urban water bodies using bottom mud aeration, which uses aeration oxidation to purify the bottom mud of water bodies and reduce the frequency of bottom mud dredging. However, due to the basic principle of gas-liquid interaction, it is difficult for oxygen generated in situ or externally applied oxygen to directly contact the bottom mud surface. Therefore, it is necessary to establish a new method to restore the aerobic state of bottom mud and remove the biogenic elements in the bottom mud. Summary of the Invention

[0005] In view of the above-mentioned defects of the prior art, in a first aspect of the present invention, a method for rapidly restoring the aerobic state of sediment and simultaneously removing carbon, nitrogen and phosphorus from the sediment is provided, comprising the following steps:

[0006] (1) Changing the suspended state of sediment in natural water bodies by oscillating the sediment to obtain suspended sediment;

[0007] (2) The photosynthesis of plants in natural water bodies creates an oxygen-rich or oxygen-supersaturated state in the water body, thereby obtaining oxygen-rich water bodies;

[0008] (3) Suspended sediments in oxygen-rich water bodies are converted to an aerobic state through oxidation reactions, reducing the carbon, nitrogen and phosphorus contents.

[0009] Preferably, in step (2), the plants are distributed in the entire vertical structure of the water body, including phytoplankton, emergent plants, and submerged plants.

[0010] Preferably, in step (2), the oxygen supersaturation state refers to 100-200% of the saturated oxygen concentration in water at 25° C. under 1 standard atmospheric pressure.

[0011] Preferably, the specific steps of step (3) are as follows: the suspended sediment undergoes an oxidation reaction in the oxygen-rich water body and gradually transforms into an aerobic state. During this process, the microbial community structure and composition of the sediment change, reducing the carbon, nitrogen and phosphorus contents.

[0012] Further preferably, in step (3), the oxidation reaction includes direct oxidation with oxygen, photochemical oxidation, and biological oxidation.

[0013] Further preferably, in the step (3), the microbial community structure and composition of the sediment change, and the typical change characteristics are a decrease in the relative abundance of sulfur-reducing bacteria and iron-reducing bacteria, and a balance between nitrogen nitrification-denitrification and ammonia oxidizing bacteria.

[0014] Further preferably, in the step (3), the approach to reducing the carbon, nitrogen and phosphorus contents includes accelerating the carbon, nitrogen and phosphorus cycle, increasing bioaccumulation efficiency and resource utilization.

[0015] The oscillation of the bottom mud in step (1) is achieved by a bottom mud suspension oscillation device. In the second aspect of the present invention, a bottom mud suspension oscillation device is provided. The bottom mud suspension oscillation device is a symmetrical structure, comprising a first concentric cylinder (11), a second concentric cylinder (12), a third concentric cylinder (13), and a fourth concentric cylinder (14) which are concentrically arranged and sequentially arranged from the outside to the inside, and also comprising a water inlet (2), a water outlet (3) and an air inlet (4); the cylinder walls and bottom walls of the four concentric cylinders are arranged in parallel, with the cylinder walls and bottom walls serving as guide plates and forming a one-way flow path between the concentric cylinders; the opening between the first concentric cylinder (11) and the second concentric cylinder (12) The first water inlet (21) is provided, and the opening of the fourth concentric cylinder (14) on the same side as the water inlet (21) is provided as the second water inlet (22); the air inlet (4) is located on the same side as the water outlet (3) and is arranged on the surface of the first concentric cylinder (11); when the device is placed in a water body, air is ventilated into the interior of the device through the air inlet (4), and bottom mud and water are sucked in through the first water inlet (21) and the second water inlet (22) at the bottom end, mixed in the interior of the device, and discharged through the water outlet (3), thereby changing the suspended state of the bottom mud.

[0016] Furthermore, the column is a cylinder or a polygonal column.

[0017] Furthermore, the bottom mud suspension oscillation device further includes a pneumatic stirring device 5 , which is disposed in the fourth concentric cylinder 14 .

[0018] Furthermore, the bottom sediment suspension oscillation device further includes a power system 6 arranged on the surface of the device, and the power system 6 is driven by electric energy, solar energy or wind energy to provide power for the movement of the bottom sediment suspension oscillation device.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0020] 1. The present invention provides a method for rapidly restoring the aerobic state of sediment and simultaneously removing carbon, nitrogen, and phosphorus from the sediment. Suspending the sediment in oxygen-rich or oxygen-supersaturated water and then restoring its aerobic state effectively solves the problems of low efficiency and high cost of the aeration technology used in the past. Secondly, in the entire process of reducing and recycling endogenous pollutants, no chemical or biological reagents are added. It is a purely ecological technology and will not cause secondary environmental problems. Finally, this method realizes the in-situ and efficient resource utilization of endogenous biogenic elements, which not only has good environmental and ecological benefits, but also generates good economic value.

[0021] 2. In the process of changing the suspended state of the bottom mud by the method of the present invention, as the bottom mud rises, a large amount of nutrients are released into the water body, which can promote the growth of phytoplankton and emergent plants such as algae, and provide nutrients for the growth of shrimp, snails and fish. At the same time, the bottom mud entering the overlying water body has a typical light shielding effect, competing with phytoplankton such as algae for light radiation, and can reduce the biomass of algae. In addition, the increase in the biomass of filter-feeding fish can effectively reduce the biomass of phytoplankton such as algae, thereby effectively reducing the risk of algal blooms. When the aerobic state of the bottom mud is restored, the water content of the bottom mud decreases and the sedimentation increases along with the decrease in the organic matter content. The reduction of endogenous load is not conducive to the growth of algae, increases the transparency of the water body, improves the landscape, and gradually restores ecological diversity. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic cross-sectional view of the sediment suspension oscillation device; in the figure, 11 is the first concentric cylinder, 12 is the second concentric cylinder, 13 is the third concentric cylinder, 14 is the fourth concentric cylinder, 21 is the first water inlet, 22 is the second water inlet, 3 is the water outlet, 4 is the air inlet, 5 is the pneumatic stirring device, and 6 is the power system. DETAILED DESCRIPTION

[0023] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.

[0024] Example 1

[0025] A bottom mud suspension oscillation device, which has a symmetrical structure and includes a first concentric cylinder 11, a second concentric cylinder 12, a third concentric cylinder 13, and a fourth concentric cylinder 14 which are concentrically arranged and sequentially sleeved from the outside to the inside, and also include a water inlet 2, a water outlet 3, and an air inlet 4; the cylinder walls and bottom walls of the four concentric cylinders are arranged in parallel, with the cylinder walls and bottom walls serving as guide plates and forming a unidirectional flow path between the concentric cylinders; the opening between the first concentric cylinder 11 and the second concentric cylinder 12 is a first water inlet 21, and the opening on the same side of the fourth concentric cylinder 14 and the water inlet 21 is a second water inlet 22; the air inlet 4 is located on the same side as the water outlet 3 and is arranged on the surface of the first concentric cylinder 11; when the device is placed in a water body, air is ventilated into the interior of the device through the air inlet 4, and the bottom mud and water are sucked in through the first water inlet 21 and the second water inlet 22 at the bottom, mixed inside the device, and then discharged through the water outlet 3, thereby changing the suspension state of the bottom mud.

[0026] Example 2

[0027] A 20-cm-diameter sediment suspension oscillator was placed in a simulated lake system measuring 80 cm in diameter and 120 cm in height. With an air intake of 5.6 L / min, the sediment was suspended in the overlying water at a frequency of 10.5 seconds. Physiological processes within the natural waters created an oxygen-rich or oxygen-supersaturated state, resulting in oxygen-enriched water. The suspended sediment underwent oxidation reactions within the oxygen-enriched water, transforming it into an aerobic state. Dissolved oxygen levels were measured using an electrochemical probe at different time intervals. At room temperature of 30°C, dissolved oxygen in the overlying water increased from 1.8 mg / L to 5.6 mg / L within 30 minutes. Sediment total nitrogen, total phosphorus, and total organic carbon were measured before and after 20 days of operation according to the methods specified in GB 17378.5-2007, "Marine Monitoring Specifications, Part 5: Sediment Analysis." The species and relative abundance of microorganisms in the sediment were determined by 16S rRNA gene sequencing. Total nitrogen in the sediment decreased from 1752 mg / kg (dry weight) to 1018 mg / kg, total phosphorus from 807 mg / kg to 624 mg / kg, and total organic carbon from 57482 mg / kg to 49013 mg / kg. The relative abundance of the bacterial genus Thiobacillus increased from 1.57% to 3.32%, while the relative abundance of the bacterial genus Desulfatiglans decreased from 1.44% to 1.09%.

[0028] Example 3

[0029] A 20cm outer diameter sediment suspension oscillator was placed in a simulated lake measuring 80cm x 60cm x 60cm. With an air intake of 11.2L / min, the sediment was suspended in the overlying water at a frequency of 1 / 5s. Physiological processes within the natural aquatic organisms created an oxygen-enriched or oxygen-supersaturated state, resulting in oxygen-enriched water. The suspended sediment underwent oxidation reactions within the oxygen-enriched water, transforming it into an aerobic state. Dissolved oxygen levels were measured at different time intervals using an electrochemical probe, and total suspended particulate matter content was determined according to GB 11901-1989, "Water Quality: Gravimetric Determination of Suspended Matter." At room temperature of 10°C, dissolved oxygen in the overlying water increased from 5.4mg / L to 9.5mg / L over 3 hours. After 24 hours, dissolved oxygen in the overlying water remained at 10.7mg / L, and total suspended particulate matter increased from 9mg / L to 53mg / L. Sediment total nitrogen, total phosphorus, and total organic carbon were measured before and after 20 days of operation according to the methods specified in GB 17378.5-2007, "Ocean Monitoring Specifications Part 5: Sediment Analysis." The species and relative abundance of microorganisms in the sediment were determined by 16S rRNA gene sequencing. After 60 days of operation, total nitrogen in the sediment decreased from 1446 mg / kg (dry weight) to 632 mg / kg, and total phosphorus decreased from 412 mg / kg to 257 mg / kg. Total organic carbon decreased from 35414 mg / kg to 33078 mg / kg. The relative abundance of the bacterial genus Thiobacillus increased from 1.02% to 2.14%, while the relative abundance of the bacterial genus Desulfatiglans decreased from 1.97% to 1.18%.

[0030] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A method for rapidly restoring the aerobic state of sediment and simultaneously removing carbon, nitrogen and phosphorus from the sediment, characterized in that: The steps include: (1) Changing the suspended state of sediment in natural water bodies by oscillating the sediment to obtain suspended sediment; (2) Through the photosynthesis of plants in natural water bodies, oxygen-rich or oxygen-supersaturated water bodies are formed, thus obtaining oxygen-rich water bodies; (3) Suspended sediments in oxygen-rich water bodies are converted to an aerobic state through oxidation reactions, reducing the carbon, nitrogen, and phosphorus contents; The oscillation of the bottom mud in step (1) is achieved by a bottom mud suspension oscillation device, which has a symmetrical structure and includes a first concentric cylinder (11), a second concentric cylinder (12), a third concentric cylinder (13), and a fourth concentric cylinder (14) which are concentrically arranged and sequentially arranged from the outside to the inside, and also includes a water inlet (2), a water outlet (3), and an air inlet (4); the cylinder walls and bottom walls of the four concentric cylinders are arranged in parallel, and the cylinder walls and bottom walls are used as guide plates to form a one-way flow path between the concentric cylinders; the water inlet (2) includes a first water inlet (21), a second water inlet (22); the first concentric cylinder (13) and the second concentric cylinder (14) are arranged concentrically and sequentially arranged from the outside to the inside, and also include a water inlet (2), a water outlet (3), and an air inlet (4); the cylinder walls and the bottom walls of the four concentric cylinders are arranged in parallel, and the cylinder walls and the bottom walls are used as guide plates to form a one-way flow path between the concentric cylinders; the water inlet (2) includes a first water inlet (21), a second water inlet (22); the first concentric cylinder (13) and the second concentric cylinder (14) are arranged concentrically and sequentially arranged from the outside to the inside, and also include a water inlet (2), a water outlet (3), and an air inlet (4); The opening between the column (11) and the second concentric column (12) is the first water inlet (21), and the opening of the fourth concentric column (14) on the same side as the first water inlet (21) is the second water inlet (22); the air inlet (4) is located on the same side as the water outlet (3) and is arranged on the surface of the first concentric column (11); when the device is placed in a water body, air is ventilated into the interior of the device through the air inlet (4), and bottom mud and water are sucked in through the first water inlet (21) and the second water inlet (22) at the bottom, mixed inside the device, and discharged through the water outlet (3), thereby changing the suspended state of the bottom mud.

2. The method according to claim 1, wherein: In the step (2), the plants are distributed in the entire vertical structure of the water body, including phytoplankton, emergent plants, and submerged plants.

3. The method according to claim 1, wherein: In the step (2), the oxygen supersaturation state refers to the dissolved oxygen concentration in water reaching 100% to 200% of its saturation concentration under the conditions of 1 standard atmospheric pressure and 25°C.

4. The method according to claim 1, wherein The specific steps of step (3) are as follows: the suspended sediment undergoes an oxidation reaction in the oxygen-rich water body and gradually changes to an aerobic state. During this process, the microbial community structure and composition of the sediment change, reducing the carbon, nitrogen and phosphorus contents.

5. The method according to claim 4, characterized in that: In the step (3), the oxidation reaction includes direct oxidation with oxygen, photochemical oxidation, and biological oxidation.

6. The method according to claim 4, wherein: The changes in the microbial community structure and composition of the sediment are typically characterized by a decrease in the relative abundance of sulfur-reducing bacteria and iron-reducing bacteria, and a balance between nitrogen nitrification-denitrification and ammonia-oxidizing bacteria. The approaches to reducing the carbon, nitrogen, and phosphorus contents include accelerating the carbon, nitrogen, and phosphorus cycle, increasing bioaccumulation efficiency, and resource utilization.

7. The method according to claim 1, wherein: The column is a cylinder or a polygonal column.

8. The method according to claim 1, wherein: The device further comprises a pneumatic stirring device (5), wherein the pneumatic stirring device (5) is arranged in the fourth concentric cylinder (14).

9. The method according to claim 1, wherein: The device further comprises a power system (6) arranged on the surface of the device, wherein the power system (6) is driven by electric energy, solar energy or wind energy and is used to provide power for the movement of the device.

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