Taihu Lake dehydrated sludge ecological nutrient soil, preparation method and application

Abstract

The invention discloses Taihu Lake dehydrated sludge ecological nutrient soil and a preparation method and application thereof.The preparation method includes the steps that dehydrated sludge is flatly laid and aired and turned and thrown in the period, and pretreated sludge is obtained; mixing the organic composted material with the pretreated sludge in batches to obtain mixed sludge; crushing equipment is used for crushing and scattering the mixed sludge, so that the Taihu Lake dehydrated sludge ecological nutrient soil with ecological safety and good physicochemical properties is prepared, and resource recycling is facilitated.

Description

Technical Field

[0001] This application relates to an ecological nutrient soil for dehydrated silt from Taihu Lake, its preparation method, and its application, belonging to the field of waste resource utilization technology. Background Technology

[0002] Over long periods of operation, lakes, rivers, and other bodies of water accumulate large amounts of silt at their bottoms. This silt is rich in nutrients such as nitrogen and phosphorus, and is one of the main endogenous sources of pollution leading to eutrophication. To improve water quality and restore the function of water bodies, bottom sediment dredging has become a routine and necessary remediation project, but it also generates a huge amount of dredged silt.

[0003] Even after dewatering, sludge remains bulky, making its disposal a pressing practical problem. Currently, the main methods for disposing of dewatered sludge are open-air dumping or landfilling. These methods not only consume significant land resources, but also pose a significant risk of secondary pollution from pollutants and potentially harmful substances such as heavy metals accumulated in the sludge, which can be leached by rainwater in the natural environment, potentially threatening surrounding water bodies and soil environments.

[0004] Dehydrated sludge is rich in organic matter, various nutrients, and clay components, theoretically possessing the potential to be transformed into a soil conditioner or cultivation substrate. However, direct application in agriculture or landscaping faces numerous technical challenges, such as: poor physical structure and low aeration and permeability; potential risks of biological contamination by pathogens; and the need to control the long-term ecological safety of heavy metals. Furthermore, the nutrient forms and proportions in dehydrated sludge may not meet the needs of plant growth.

[0005] Therefore, developing a resource utilization technology that can overcome the above-mentioned defects and transform dewatered sludge into stable, safe, and usable ecological nutrient soil can not only solve the sludge disposal dilemma and eliminate environmental hazards, but also realize the resource recycling of waste, with significant comprehensive benefits. Summary of the Invention

[0006] The purpose of this application is to overcome the shortcomings of the existing technology and provide an ecological nutrient soil for dehydrated silt from Taihu Lake, its preparation method and application, so as to solve the technical problem that silt cannot be directly and safely utilized.

[0007] To achieve the above objectives, the technical solution adopted in this application is as follows: In a first aspect, this application provides a method for preparing ecological nutrient soil from dehydrated silt from Taihu Lake, comprising: The dehydrated sludge from Taihu Lake was spread out in a 20-50cm thickness and left to dry for 5-7 days, turning it over during the process to obtain pre-treated sludge with a moisture content of 25-35%. The organic compost was mixed with the pretreated sludge in batches to obtain mixed sludge; the total amount of organic compost added accounted for 5% to 15% of the sludge mass. The mixed silt was crushed and broken down using crushing equipment to produce Taihu dewatered silt ecological nutrient soil.

[0008] In conjunction with the first aspect, the initial moisture content of the dehydrated sludge from Taihu Lake is 45% to 60%.

[0009] Furthermore, the turning and turning is performed 2 to 3 times; the organic compost is mixed with the pretreated sludge in batches 2 to 4 times.

[0010] Furthermore, the crushing equipment is a rotary hammer crusher and / or a rotary blade crusher.

[0011] Furthermore, the organic compost includes, but is not limited to, any one or more of the following: composted animal manure, composted agricultural tailings, composted garden waste, composted sludge, composted mushroom residue, and composted traditional Chinese medicine residue.

[0012] Furthermore, the decomposed animal manure includes cow manure, and the decomposed agricultural waste includes stevia residue.

[0013] Secondly, this application provides an ecological nutrient soil for dehydrated silt from Taihu Lake, prepared according to the method described in the first aspect, wherein the organic matter content of the ecological nutrient soil for dehydrated silt from Taihu Lake is 3% to 8%.

[0014] Thirdly, this application provides an application of Taihu Lake dehydrated silt ecological nutrient soil, which is used for farmland topsoil improvement, seedling cultivation, pit and pond backfilling, or lawn growth substrate.

[0015] Compared with the prior art, the beneficial effects achieved by this application are as follows: This application achieves uniform moisture evaporation by spreading dehydrated sludge to a specific thickness of 20-50cm and combining it with a 5-7 day drying cycle and regular turning. At the same time, the sunlight exposure during the turning process effectively inactivates pathogens and parasite eggs, solving the problems of low efficiency and uneven results of traditional natural drying. Adding 5-15% organic compost to the pretreated sludge achieves the dual purpose of nutrient addition and heavy metal stabilization. It not only replenishes organic matter and nutrients, but also uses functional groups such as humic acid in the compost to passivate potential heavy metal ions in the sludge, reduce their bioavailability, and improve the ecological safety of the product. Using crushing equipment to break up the mixed sludge breaks down the original dense structure of the sludge, improves the pore and aggregate structure of the dewatered sludge ecological nutrient soil, and enhances its air permeability and water permeability. Attached Figure Description

[0016] Figure 1 This is a flowchart of a method for preparing ecological nutrient soil from dehydrated silt in Taihu Lake, provided in an embodiment of this application. Detailed Implementation

[0017] The present application will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and should not be used to limit the scope of protection of the present application.

[0018] like Figure 1 As shown, this application provides a method for preparing dehydrated silt ecological nutrient soil, which specifically includes the following steps: Dehydrated sludge with an initial moisture content of 45% to 60% was spread out in a 20 to 50 cm thickness and dried for 5 to 7 days, turning it over 2 to 3 times during the period to obtain pre-treated sludge with a moisture content of 25% to 35%. The organic compost was mixed with the pretreated sludge in 2-4 batches to obtain mixed sludge; the total amount of organic compost added accounted for 5%-15% of the sludge mass. The mixed sludge is crushed and dispersed using crushing equipment to obtain dewatered sludge ecological nutrient soil, in which the organic matter content is 3% to 8%. The crushing equipment is a rotary hammer crusher or a rotary blade crusher, or a combination of the two.

[0019] Organic composting materials include, but are not limited to, any one or more of the following: composted animal manure, composted agricultural waste, composted garden waste, composted sludge, composted mushroom residue, and composted traditional Chinese medicine residue. In this embodiment, cow manure is used as the composted animal manure, and stevia residue is used as the composted agricultural waste.

[0020] The dehydrated sludge used in Examples 1 to 3 of this application is all dehydrated sludge from Taihu Lake.

[0021] Example 1:

[0022] The Taihu Lake dehydrated sludge with an initial moisture content of 60% was spread out in a 20cm thickness and dried for 5 days. During the drying process, it was mechanically turned over once on the 2nd and 4th day. Specifically, a tracked turning machine was used, and the turning depth was 20cm. After the drying was completed, the pre-treated sludge was obtained with a moisture content of 25%.

[0023] Add organic compost: Mix 50% cow manure and 50% stevia in two batches, using a 5% ratio, and add the organic compost to the pretreated sludge. First, add the first batch of organic compost, accounting for 50% of the total amount, and use a twin-shaft mixer at 30 rpm for 10 minutes to initially mix it. Then add the second batch of organic compost, the remaining 50%, and continue mixing for 15 minutes until it is evenly mixed to obtain the mixed sludge.

[0024] A rotary hammer crusher was used to crush and disperse the mixed silt. The specific rotation speed of the rotary hammer crusher was 1000 rpm, the screen aperture was 10 mm, and the processing time was 10 minutes. Taihu dewatered silt ecological nutrient soil was produced. After testing, the organic matter content of the dewatered silt ecological nutrient soil was found to be about 3%, which is suitable for improving the topsoil of farmland.

[0025] Example 2:

[0026] The dehydrated sludge from Taihu Lake, with an initial moisture content of 55%, was spread out in a 50cm thickness and left to dry for 7 days. During the drying process, it was mechanically turned over on the 2nd, 4th, and 6th days using a wheeled turner to a depth of 50cm to promote moisture evaporation and microbial inactivation. After drying, the pre-treated sludge had a moisture content of 35%.

[0027] The organic compost was mixed with the pretreated sludge in three batches: the organic compost consisted of 50% composted cow manure and 50% composted stevia residue, with a total addition of 15% of the sludge mass. First, one-third of the total organic compost was added and mixed for 15 minutes at 25 rpm using a trough mixer; then another one-third of the total organic compost was added and mixed for another 15 minutes; finally, the remaining organic compost was added and mixed for 20 minutes to ensure uniform mixing, resulting in a mixed sludge.

[0028] The mixed silt was crushed and dispersed using a rotary blade crusher at a speed of 1200 rpm with a blade gap of 5 mm for 15 minutes to produce Taihu dewatered silt ecological nutrient soil. Tests showed that the organic matter content of the dewatered silt ecological nutrient soil was about 7%, the porosity was increased to more than 40%, and it had good air permeability and water permeability, making it suitable for seedling cultivation or lawn growth substrate.

[0029] Example 3:

[0030] The dehydrated sludge from Taihu Lake, with an initial moisture content of 45%, was spread out in a 35cm thickness and left to dry for 6 days. During the drying process, it was mechanically turned over twice, on the 3rd and 5th days, using a loader in conjunction with a turning device to turn it to a depth of 35cm, achieving uniform drying and disinfection. After drying, the pre-treated sludge was obtained, with a moisture content of 33%.

[0031] The organic compost was mixed with the pretreated sludge in two batches: the organic compost consisted of 50% composted cow manure and 50% composted stevia residue, with a total addition amount of 10% of the sludge mass. First, 50% of the total organic compost was added and mixed with a spiral mixer at 35 rpm for 12 minutes; then the remaining organic compost was added and the mixture was continued for 18 minutes until it was evenly mixed to obtain the mixed sludge.

[0032] The Taihu dewatered sludge mixed with organic compost was crushed and dispersed using a rotary hammer crusher at 1100 rpm with an 8mm screen aperture for 12 minutes to produce Taihu dewatered sludge ecological nutrient soil. Tests showed that the nutrient soil had an organic matter content of about 5%, a stable granular structure, and a reduced heavy metal migration rate, making it suitable for pond backfilling or soil improvement.

[0033] The Taihu dehydrated silt ecological nutrient soil prepared according to any of the above embodiments can be used for farmland topsoil improvement, seedling cultivation, pit and pond backfilling, or lawn growth substrate.

[0034] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A preparation method of Taihu dewatered sludge ecological nutrient soil, characterized in that, The method comprises the following steps: The dewatered sludge of Taihu Lake is laid flat in a thickness of 20-50 cm and dried for 5-7 days, and the sludge is turned over during the drying process to obtain pretreated sludge, wherein the moisture content of the pretreated sludge is 25-35%; The organic mature material is mixed with the pretreated sludge in batches to obtain mixed sludge, wherein the total amount of the organic mature material accounts for 5-15% of the mass of the sludge. The mixed sludge is crushed and scattered by using a crushing device to obtain the ecological nutrient soil of the dewatered sludge of Taihu Lake.

2. The method of claim 1, wherein, The initial moisture content of the dewatered sludge of Taihu Lake is 45-60%.

3. The method of claim 1, wherein, The number of times of turning over is 2-3 times, and the number of times of mixing the organic mature material with the pretreated sludge in batches is 2-4 times.

4. The method of claim 1, wherein, The crushing device is a rotary hammer type and / or a rotary blade type crusher.

5. The method of claim 1, wherein, The organic mature material includes, but is not limited to, any one or more of the following: mature animal manure, mature agricultural tailings, mature garden waste, mature sludge, mature mushroom residue and mature traditional Chinese medicine residue.

6. The method of claim 5, wherein, The mature animal manure includes cow dung, and the mature agricultural tailings include sweetleaf chrysanthemum residue.

7. A Taihu Lake dewatered sludge ecological nutrient soil, characterized in that, The ecological nutrient soil of the dewatered sludge of Taihu Lake prepared by the method of any one of claims 1-6 has an organic matter content of 3-8%.

8. The use of the Taihu sludge dewatering ecological nutrient soil according to claim 7, characterized in that, The dewatered sludge ecological nutrient soil is used for farmland tillage layer improvement, seedling cultivation, pit and pond backfilling or lawn growth base material.

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