On-site consumption method for mud flat wetland sludge

Abstract

The invention provides a mud flat wetland sludge on-site consumption method, which is characterized by comprising the following steps: S1, sampling analysis: carrying out sampling analysis on sludge in a consumption area; s2, grid excavation: performing grid division on the sludge in the absorption area, dividing the sludge into N grid units, digging out the sludge in M grid units, stacking the sludge around the absorption area to form a cofferdam, backfilling the sludge in the M grid units of the next batch into the M grid units of the previous batch in a layered manner, and so on, the grid units in the whole area are all processed; and the mud flat wetland sludge does not need to be dredged and transported outwards, so that the method is environment-friendly, simple and efficient.

Description

Technical Field

[0001] The invention relates to the technical field of environmental protection, and in particular to a method for on-site disposal of tidal flat wetland silt. Background Art

[0002] Tidal flat wetland silt is a special type of sediment formed in coastal intertidal zones or inland wetlands. It is mainly formed by the gradual deposition of sediment carried by rivers, suspended particles brought by ocean tides and waves, and biological remains in wetlands. Its high water content makes it soft or fluid, easy to deform, and has poor physical and mechanical properties. Tidal flat silt affects the water quality of the water around the tidal flat, and its texture and composition are not conducive to plant growth. It also affects the reproduction and habitat of aquatic organisms during the flood season.

[0003] At present, the disposal of tidal flat silt mainly relies on dredging, in which the silt is dug out and then transported out. This method wastes a lot of manpower and material resources, and the disposal of the transported silt is still a problem. Therefore, a method for on-site disposal of tidal flat wetland silt is urgently needed to solve the problem. Summary of the invention

[0004] In order to solve at least one of the above technical problems, the present invention provides a method for on-site disposal of tidal flat wetland sludge. This method rationally relies on microbial decomposition as the main method and plant disposal as the auxiliary method, thereby achieving on-site disposal of tidal flat sludge, which is simple, efficient and environmentally friendly.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A method for on-site disposal of tidal flat wetland sludge, characterized in that it comprises the following steps:

[0007] S1. Sampling and analysis: Sampling and analysis of sludge in the disposal area;

[0008] S2. Grid excavation: The silt in the disposal area is grid-divided into N grid units, and the silt in M ​​grid units is excavated and piled around the disposal area to form a embankment, and the silt in the next batch of M grid units is backfilled into the previous batch of M grid units in layers, and so on, until all the grid units in the entire area are processed;

[0009] S3, microbial decomposition: drying a portion of the backfilled sludge, mixing it with microbial agents and activated carbon particles to form bacterial sludge, which is added when the sludge is backfilled in layers;

[0010] S4. Plant absorption: A variety of plants are combined to build plant communities to absorb silt;

[0011] S5. Post-monitoring and maintenance: regular inspection and maintenance.

[0012] In the above technical scheme, according to the characteristics of tidal flat wetland silt, on-site disposal of tidal flat wetland silt is achieved through sampling and analysis, grid excavation, microbial decomposition, plant consumption, and post-monitoring and maintenance. There is no need to dredge and transport the silt, which is environmentally friendly, simple and efficient. Adding bacterial sludge to each layer is conducive to building a continuous microbial ecological niche. When the microbial activity of a backfill layer decreases or the community structure changes, the microorganisms in the adjacent layers can be supplemented and adjusted by the diffusion of metabolites, cell migration, etc., to ensure that the microbial treatment process in the entire backfill sludge is carried out continuously and stably.

[0013] Preferably, in step S1, the sludge is sampled and analyzed mainly for one or more of the following: pH value, organic matter, salt content, soil moisture content, clay weight, density and porosity.

[0014] In the above technical solution: sampling and analysis of sludge provides theoretical support for the ratio of various fungi in subsequent microbial decomposition.

[0015] Preferably, in step S2, the slope of the embankment is a gentle slope, and the slope is constructed by mixing geotextile bags, local sand and gravel, and excavated silt, and the slope is 1-1:3.

[0016] In the above technical solution: building embankments in areas where wetland sludge needs to be disposed of on site can prevent the spread of sludge during the disposal process, and to a certain extent ensure the exchange of internal and external water bodies during the flood season. The gentle slope design can reduce the erosion of the embankments by water flow.

[0017] Preferably, the microbial agent in step S3 includes Bacillus, flocculent bacteria, nitrifying bacteria and denitrifying bacteria.

[0018] Preferably, the mass ratio of the bacterial agent is Bacillus: floc bacteria: nitrifying bacteria: denitrifying bacteria = (4-6): (2-3): (1-1.5): (1-1.5).

[0019] Preferably, the thickness of the layered backfill is 30-40 cm, and the tidal flat mud is plowed four weeks after adding the bacterial mud, with a plowing depth of 50-70 cm, and bacterial mud is added again after plowing.

[0020] In the above technical scheme: Bacillus' powerful ability to decompose organic macromolecules enables it to play a key role in treating animal and plant residues, organic debris, etc. in sludge. A higher proportion helps to quickly decompose organic pollutants and improve the texture and fertility of sludge. Floc bacteria are an important component of activated sludge. They can secrete sticky substances to bond sludge particles together to form larger flocs, which is conducive to the sedimentation and separation of sludge. At the same time, they can also adsorb and decompose organic pollutants in sewage. Nitrifying bacteria convert ammonia nitrogen into nitrite and nitrate, and denitrifying bacteria reduce nitrate and nitrite to nitrogen gas to prevent excessive nitrogen from accumulating in the sludge and causing eutrophication. They cooperate with nitrifying bacteria to maintain nitrogen balance. Tillage can break the compacted layer on the surface of the sludge, increase soil permeability, and re-add microbial agents to ensure the survival of microorganisms in the sludge, so as to form a symbiotic relationship with the roots and stems of subsequently planted plants.

[0021] Preferably, in the plant consumption in step S3, pioneer plants are first planted, and plant community optimization is performed later. The pioneer plants are one or more of Suaeda salsa, Phragmites australis and Acorus calamus, and the later plant community optimization includes planting one or more of Spartina alterniflora, Lythrum salicaria and Scolopendra subspinipes.

[0022] In the above technical scheme: the structure of the plant community can make full use of the ecological functions of different plants, combining the anti-scouring ability of Spartina alterniflora, Lythrum salicaria and Aquilegia solani, the adaptability of Suaeda salsa to high-salt environment and the strong soil-fixing and nutrient absorption ability of Phragmites australis, thereby improving the efficiency of silt disposal. As the plants grow and reproduce, the plant residues combined with microbial agents can also increase the organic matter content of the silt and improve the soil properties of the silt.

[0023] Preferably, the step S5 of regular monitoring and maintenance includes:

[0024] a) Prune and replant plants every quarter;

[0025] b) Detect the types and quantity of microorganisms in sludge every six months and supplement microbial agents based on the results;

[0026] In the above technical solution: timely monitoring and maintenance can replenish microorganisms and replant plants in time, ensuring the efficiency of sludge disposal.

[0027] Preferably, steps S1 and S2 are performed during the dry season, and step S3 is performed during the transition from the dry season to the wet season.

[0028] In the above technical scheme: the tidal flat silt is in the open air during the dry season, which is conducive to its sampling and analysis and the construction of surrounding embankments, reducing costs. Microbial decomposition is carried out during the transition from the dry season to the flood season, when the weather turns warmer, which is conducive to the activity of microorganisms.

[0029] Beneficial effects:

[0030] The present invention provides a method for on-site disposal of tidal flat wetland silt. According to the characteristics of tidal flat wetland silt, the on-site disposal of tidal flat wetland silt is achieved without dredging and transporting the silt. The method is environmentally friendly, simple and efficient. It mainly relies on microbial decomposition and is supplemented by plant community construction. It has little pollution and damage to the environment, and is also beneficial to regional ecological restoration.

[0031] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention. Example

[0032] A section of the Wanhe River in Anqing City, Anhui Province was selected as the experimental site. Anqing City has obvious seasonal precipitation differences. In the rainy season, the river flow increases and the flow rate accelerates, carrying a large amount of sediment and other substances; in the dry season, the water level drops, the water flow slows down, and the sediment will settle to form mud on the beach. In the dry season in winter, the riverbed of some sections of the Wanhe River is exposed, and a large amount of silt accumulates on the beach.

[0033] The method for on-site disposal of tidal flat wetland sludge in the embodiment comprises the following steps:

[0034] Step 1: Randomly sample the silt on the tidal flat during the dry season, measure and record the water content, pH value, organic matter, powder ratio, density and porosity of the silt. The results are shown in Table 1.

[0035]

[0036] Table 1

[0037] The test results in Table 1 are mainly the theoretical basis for subsequent work. The silt soil quality (ratio of powder and particles) mainly affects the slope during embankment construction. The pH value and organic matter content affect the mass ratio of Bacillus, flocculent bacteria, nitrifying bacteria and denitrifying bacteria in the microbial agent. The measurement results are also used to judge the subsequent disposal effect.

[0038] Step 2: Divide the silt in the disposal area into N grid units, dig out the silt in M ​​(M < N) grid units and pile them around to form a dike. According to the test results of step 1, the silt here is sandy and has low shear strength. Therefore, geotextile bags, local sand and gravel, and excavated silt are mixed and filled to construct a dike with a slope of 1:1.5. The dike is 30 cm higher than the historical average water level in the flood season. Geotextile is laid at the bottom of the dike, and local plants such as reeds and willow branches are woven into bundles and laid on the slope. The silt in the next batch of M grid units is backfilled in layers into the previous batch of M grid units, and so on, until all the grid units in the entire area are processed. The thickness of the layered backfill is 30 cm.

[0039] Step 3: Mix the bacterial agents in a mass ratio of Bacillus: floc bacteria: nitrifying bacteria: denitrifying bacteria = 5:2.5:1.5:1, and add 200g / ㎡. Then mix them with dry silt and activated carbon particles to form bacterial sludge. Spread them in layers on the silt surface during backfilling. After 4 weeks, plow the tidal flat silt with a plowing depth of 50cm. After plowing, test the survival of microorganisms in the silt. The results are shown in Table 2.

[0040]

[0041] Table 2

[0042] From Table 2, we know that the survival rate of microorganisms is about 70%, and the survival rates of various bacterial agents are basically the same. Microbial agents can be added again according to this ratio. In order to volatilize the initial amount of bacterial agents added, the amount added this time is 200×(1-70%)=60g / ㎡.

[0043] It should be noted that in this embodiment, sampling analysis, grid excavation and tillage after the first addition of bacterial sludge are carried out in the dry season in winter, the bacterial sludge is added again after tillage in spring, and the subsequent plant absorption is also carried out in spring and summer.

[0044] Step 4: Through soil analysis, the fertility of the beach mud here is low, and it is planted within the enclosure, so it is suitable for the cultivation of Salicornia herba. Therefore, the pioneer plant used in this embodiment is Salicornia herba. The Salicornia herba seeds are soaked in warm water at 30-40°C for 24 hours and then evenly sown on the mud surface. The sowing amount is 10-15 grams per square meter. The seeds are mixed with gravel during sowing, and the weight ratio of seeds to gravel is 1:3. After sowing, a light rake can be used to gently rake the seeds into the mud surface, with a depth of about 0.5-1 cm, to ensure that the seeds are in full contact with the soil.

[0045] As time goes by, the Suaeda salsa begins to take root, sprout and grow. It is also the flood season and there will be some water flow inside the embankment. At this time, the plant community begins to be built, and Lythrum sapodilla is planted in the nearshore area outside the Suaeda salsa. The stems of Lythrum sapodilla are relatively tough, and its roots can also fix soil silt and resist the impact of water flow.

[0046] It should be noted that, when constructing the plant community, organic fertilizer is added as needed to improve soil fertility and structure. The organic fertilizer implemented in this embodiment is bamboo charcoal bio-organic fertilizer.

[0047] Step 6: Prune and replant the plants every quarter; test the types and numbers of microorganisms in the sludge every six months, and supplement the microbial agents based on the results.

[0048] Step 7: During the dry season of the following year, the mud on the tidal flats in the treatment area was sampled and analyzed, and the soil moisture content, pH value, organic matter, powder ratio (clay density), density and porosity were measured and recorded. The results are shown in Table 3.

[0049]

[0050] Table 3

[0051] Comparing and analyzing the corresponding test data in Table 1 and Table 3, the soil moisture content in this area has decreased by 15%, the soil pH value has tended to be neutral, the organic matter content has increased, and it is more suitable for the growth of plant communities. The powder-to-particle ratio in the soil has decreased, the density has increased, and the porosity has increased, all of which fully demonstrates that the structural function of the soil here has been improved and has reached the normal soil standard, completing the silt disposal work in the embankment area.

[0052] Step 8: Remove the fence around this area.

[0053] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for on-site disposal of tidal flat wetland sludge, characterized in that: The following steps are involved: S1. Sampling and analysis: Sampling and analysis of sludge in the disposal area; S2. Grid excavation: Divide the silt rows in the disposal area into N grid units, dig out the silt in M ​​grid units and pile them around the disposal area to form a embankment, and then fill the silt in the next batch of M grid units in layers into the previous batch of M grid units, and so on, until all the grid units in the entire area are processed; S3, microbial decomposition: drying a portion of the backfilled sludge, crushing it and mixing it with microbial agents and activated carbon particles to form bacterial sludge, which is added when the sludge is backfilled in layers; S4. Plant absorption: A variety of plants are combined to build plant communities to absorb silt; S5. Post-monitoring and maintenance: Regular monitoring and maintenance.

2. The method for on-site disposal of tidal flat wetland sludge according to claim 1, characterized in that: In the step S1, the sludge is sampled and analyzed mainly for one or more of the following: pH value, organic matter, salt content, soil moisture content, powder ratio, density and porosity.

3. The method for on-site disposal of tidal flat wetland sludge according to claim 1, characterized in that: In the step S2, the slope of the dam body is a gentle slope, and the slope is constructed by mixing geotextile bags, local sand and gravel and excavated silt, and the slope is 1-1:

3.

4. The method for on-site disposal of tidal flat wetland sludge according to claim 1, characterized in that: The microbial agent described in step S3 includes bacillus, flocculent bacteria, nitrifying bacteria and denitrifying bacteria.

5. The method for on-site disposal of tidal flat wetland sludge according to claim 4, characterized in that: The mass ratio of the microbial agent is Bacillus: Floc bacteria: Nitrifying bacteria: Denitrifying bacteria = (4-6): (2-3): (1-1.5): (1-1.5).

6. The method for on-site disposal of tidal flat wetland sludge according to claim 1, characterized in that: The thickness of the layered backfill is 30-40 cm. Four weeks after adding the bacterial mud, the tidal flat mud is plowed to a depth of 50-70 cm, and the bacterial mud is added again after plowing.

7. The method for on-site disposal of tidal flat wetland sludge according to claim 1, characterized in that: In the step S3, the plant consumption is carried out by first planting pioneer plants and then optimizing the plant community. The pioneer plants are one or more of Suaeda salsa, Phragmites australis and Acorus calamus. The later plant community optimization includes planting one or more of Spartina alterniflora, Lythrum salicaria and Scolopendra subspinipes.

8. The method for on-site disposal of tidal flat wetland sludge according to claim 1, characterized in that: The step S5 of regular monitoring and maintenance includes: a) Prune and replant plants every quarter; b) Test the types and quantity of microorganisms in the sludge every six months and supplement microbial agents based on the results.

9. The method for on-site disposal of tidal flat wetland sludge according to claim 1, characterized in that: The steps S1 and S2 are performed during the dry season, and the step S3 is performed during the transition from the dry season to the wet season.

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