Treatment method for reclaiming farmland through dredged sludge

Abstract

According to the treatment method for reclaiming the farmland by the dredged sludge, the resource utilization of the dredged sludge is realized, the potential fertility of the dredged sludge is fully exerted, the farmland area is increased, the farmland reclamation cost is saved, and the problems that the dredged sludge of a storage yard occupies a large amount of land for a long time and influences the surrounding ecological environment are solved.

Description

Technical Field

[0001] The invention belongs to the field of sludge transformation and relates to a processing method for dredging sludge to reclaim farmland. Background Art

[0003] Among the resource utilization directions of dredged sludge, farmland utilization is considered to be the most promising disposal method. Dredged sludge is mainly composed of inorganic minerals such as silicate and is rich in organic matter and nutrients. It is very close to the soil composition and is safer than urban sludge. It is a good fertilizer source. However, due to the limitations of dredging technology, the moisture content of newly filled dredged sludge is generally as high as 400% to 900%, which does not meet the conditions for direct agricultural land resource utilization. Summary of the invention

[0004] In order to solve the technical problems existing in the prior art, the present invention provides a treatment method for dredged sludge to reclaim farmland, which realizes the resource utilization of dredged sludge, gives full play to the potential fertility of dredged sludge, increases the area of ​​farmland, saves the cost of farmland reclamation, and solves the problem that dredged sludge in the yard occupies a large amount of land for a long time and affects the surrounding ecological environment.

[0005] In order to achieve the above technical effects, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for dredging silt to reclaim farmland, the method comprising:

[0007] (1) To measure the physical, chemical and biological properties of dredged sludge;

[0008] (2) conducting a safety assessment of the dredged sludge for farmland use based on the measurement results of step (1);

[0009] (3) dewatering the dredged sludge to obtain dewatered dredged sludge;

[0010] (4) performing strength testing on the dewatered dredged sludge in step (3), and reinforcing the dewatered dredged sludge whose strength does not meet the construction requirements;

[0011] (5) treating the dewatered dredged sludge whose strength meets the construction requirements for farmland reclamation to obtain dredged sludge for farmland reclamation;

[0012] (6) selecting crops to be planted based on the soil characteristics and climatic conditions of the farmland reclaimed from the dredged sludge in step (5);

[0013] (7) To monitor the soil and crop conditions of farmland reclaimed from dredged silt and to evaluate the utilization effect of farmland reclaimed from dredged silt.

[0014] As a preferred technical solution of the present invention, the physical performance indicators include soil type, density, particle size, natural water content and critical water content.

[0015] And / or, the chemical performance indicators include heavy metal content, organic matter content, hydrolyzable nitrogen content, effective phosphorus content and available potassium content.

[0016] And / or, the biological performance index includes a biological toxicity index.

[0017] As a preferred technical solution of the present invention, in step (2), the safety of dredged sludge for farmland utilization is evaluated based on heavy metal content and biological toxicity indicators.

[0018] As a preferred technical solution of the present invention, the dehydration treatment in step (3) includes any one or a combination of at least two of pressure filtration dehydration, centrifugal separation dehydration, air-permeable vacuum rapid mud-water separation or chemical solidification dehydration.

[0019] As a preferred technical solution of the present invention, the strength test in step (4) uses any one of a falling cone penetrometer, a cross plate shear meter or a flat shovel dilatometer.

[0020] As a preferred technical solution of the present invention, step (5) farmland reclamation and treatment includes investigation and evaluation, planning and design, land leveling, soil improvement, mechanical loosening, field roads and supporting facilities.

[0021] As a preferred technical solution of the present invention, soil improvement includes improving the texture and enhancing the fertility of the dredged sludge.

[0022] As a preferred technical solution of the present invention, the quality of the improved material blended in the texture improvement = the quality of the dried sludge × (x 目标 -x 实际 )×η;

[0023] Among them, x 目标 is the target value of improved texture of dredged sludge, x 实际 is the actual value of the improved texture of the dredged sludge, and η is the adjusted mixing ratio of the improved material.

[0024] As the preferred technical solution of the present invention, the mass of nutrient material blended in fertility improvement = mass of dried sludge × (y 目标 -y 实际 )×ξ;

[0025] Among them, y 目标 is the target value of nutrients in dredged sludge, y 实际 is the actual value of nutrients in dredged sludge, and ξ is the adjusted mixing ratio of nutrients.

[0026] As a preferred technical solution of the present invention, the soil indicators of the reclaimed farmland monitored in step (7) include soil moisture and fertility.

[0027] And / or, the crop planting indicators of the reclaimed farmland monitored in step (7) include survival rate and growth potential indicators.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects:

[0029] (1) The present invention provides a method for reclaiming farmland from dredged sludge, which realizes the resource utilization of dredged sludge and gives full play to the potential fertility of dredged sludge by using environmentally friendly and readily available improved materials, thereby increasing the area of ​​farmland, saving the cost of farmland reclamation, and solving the problem that dredged sludge from the storage yard occupies a large amount of land for a long time and affects the surrounding ecological environment;

[0030] (2) The present invention provides a method for reclaiming farmland from dredged sludge. The method determines the dredged sludge performance indexes, determines the treatment method for farmland more reasonably, and improves the utilization rate of the dredged sludge. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the design process of dredging silt to reclaim farmland provided by the present invention.

[0032] Figure 2 A schematic plan view of the method of reclaiming farmland by dredging silt provided by the present invention.

[0033] Figure 3 A cross-sectional schematic diagram of the method of dredging silt to reclaim farmland provided by the present invention.

[0034] Figure 4 This is a site map of land leveling and silt drying improvement in Example 1 of the present invention.

[0035] Figure 5 This is a site map of field roads and irrigation and drainage facilities in Example 1 of the present invention.

[0036] In the figure: 1. Base backfill layer of farmland reclamation area; 2. Existing non-backfill area; 3. Planned roads; 4. Farmland cultivation layer; 5. Irrigation and drainage supporting equipment.

[0037] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION

[0038] The technical solution of the present application is further described below through specific implementation methods.

[0039] The specific embodiment of the present invention provides a method for dredging silt to reclaim farmland, the method comprising:

[0040] (1) To measure the physical, chemical and biological properties of dredged sludge;

[0041] (2) conducting a safety assessment of the dredged sludge for farmland use based on the measurement results of step (1);

[0042] (3) dewatering the dredged sludge to obtain dewatered dredged sludge;

[0043] (4) performing strength testing on the dewatered dredged sludge in step (3), and reinforcing the dewatered dredged sludge whose strength does not meet the construction requirements;

[0044] (5) treating the dewatered dredged sludge whose strength meets the construction requirements for farmland reclamation to obtain dredged sludge for farmland reclamation;

[0045] (6) selecting crops to be planted based on the soil characteristics and climatic conditions of the farmland reclaimed from the dredged sludge in step (5);

[0046] (7) To monitor the soil and crop conditions of farmland reclaimed from dredged silt and to evaluate the utilization effect of farmland reclaimed from dredged silt.

[0047] In the present invention, the risk and feasibility of utilizing dredged sludge in farmland are evaluated by testing the basic performance indicators of dredged sludge, and then the dredged sludge is quickly dehydrated to test whether its mechanical strength meets the needs of farmland construction, and then a series of farmland reclamation treatments are implemented, and finally the reclaimed farmland indicators are evaluated and accepted through crop planting experiments.

[0048] In a specific embodiment of the present invention, the dredged sludge is sampled, and the physical property indexes, chemical property indexes and biological property indexes of the samples are measured.

[0049] In a specific embodiment of the present invention, a sludge sampler is used to sample the dredged sludge, the sampling process follows the equal random principle, and the sampling points include the entire dredged sludge yard coverage area.

[0050] In one specific embodiment of the present invention, the number of samples taken is increased for areas with obvious pollutants and pollution sources.

[0051] In one specific embodiment of the present invention, the physical property indicators include soil type, density, particle size, natural moisture content and critical moisture content.

[0052] In a specific embodiment of the present invention, the chemical performance indicators include heavy metal content, organic matter content, hydrolyzable nitrogen content, effective phosphorus content and available potassium content.

[0053] In one specific embodiment of the present invention, the biological performance index includes a biological toxicity index.

[0054] In a specific embodiment of the present invention, the physical performance indicators, chemical performance indicators and biological performance indicators are not limited to the indicators listed above. The selection of indicators can be adjusted according to the properties of the dredged sludge and local environmental conditions, and no specific limitation is made here.

[0055] In a specific embodiment of the present invention, each of the physical performance indexes, chemical performance indexes and biological performance indexes can be measured by conventional testing methods in the art, and no specific limitation is made herein.

[0056] In a specific embodiment of the present invention, the heavy metal content determination includes the content of total cadmium, total mercury, total lead, total chromium, total arsenic, total nickel and total copper.

[0057] In a specific embodiment of the present invention, in step (2), the safety of dredged sludge for farmland utilization is evaluated based on heavy metal content and biological toxicity indicators.

[0058] In a specific embodiment of the present invention, the heavy metal content and biological toxicity index range are reasonably evaluated according to the "Agricultural Land Soil Pollution Risk Control Standard" (GB15618-2018). During work, it is necessary to avoid the contamination of crops planted later by heavy metals and biological toxicity to ensure the safety of farmland soil after reclamation.

[0059] In a specific embodiment of the present invention, the dehydration treatment in step (3) includes any one or a combination of at least two of pressure filtration dehydration, centrifugal separation dehydration, air permeable vacuum rapid mud-water separation or agent solidification dehydration.

[0060] In a specific embodiment of the present invention, the strength test in step (4) uses any one of a falling cone penetrometer, a cross plate shear meter, and a flat shovel dilatometer.

[0061] In a specific embodiment of the present invention, the purpose of strength testing is to check whether the dredged sludge meets the requirements for the entry of light construction machinery. If not, the dredged sludge after dehydration and drying needs to be reinforced to prevent the light machinery from sinking into the mud during the process of farmland reclamation, affecting the subsequent construction process.

[0062] In a specific implementation of the present invention, the requirements for the entry of light construction machinery may be as shown in Table 1.

[0063] Table 1

[0064] <![CDATA[Strength f cu / kPa]]> ＜35 35～60 ＞60 Construction suitability Discomfort suitable good

[0065] In a specific embodiment of the present invention, the reinforcement treatment may include compaction treatment, fiber reinforcement treatment, and polymer reinforcement treatment. The compaction treatment is to compact the dehydrated dredged sludge by mechanical equipment to increase its density and compressive strength; the fiber reinforcement treatment is mainly to add straw fibers to the dehydrated dredged sludge to enhance its strength and toughness; the polymer reinforcement treatment is to add high molecular polymers to the dehydrated sludge to enhance the bonding properties, so as to improve the density and strength of the sludge.

[0066] In a specific embodiment of the present invention, step (5) farmland reclamation and treatment includes investigation and evaluation, planning and design, land leveling, soil improvement, mechanical loosening, field roads and supporting facilities.

[0067] In a specific embodiment of the present invention, the investigation and evaluation is to conduct a field survey of the proposed reclamation area to evaluate the soil conditions, terrain characteristics, water source conditions and the volume of dredged silt to determine the drainage and irrigation needs and the scale of reclamation.

[0068] In a specific implementation manner of the present invention, the planning and design is mainly based on the survey results to rationally plan the field area, irrigation and drainage configuration, road layout, and planting layout of the farmland in the reclamation area.

[0069] In a specific embodiment of the present invention, land leveling is mainly carried out for land reclamation and surface leveling in the reclamation area. The dredged mud with high impurity rate (including crushed stone, gravel, etc.) and low fertility in the land reclamation can be used as the base backfill layer of farmland; the dredged silt with high fertility is used as the farmland cultivating layer, and the land reclamation adopts the balance of filling and excavation based on the principle of proximity. The surface height difference is controlled at ±5cm to eliminate the height difference and provide a flat working surface for subsequent soil improvement.

[0070] In one specific embodiment of the present invention, soil improvement includes improving the texture and enhancing the fertility of the dredged sludge.

[0071] In one specific embodiment of the present invention, soil improvement may be performed by adding mudstone, coal slag, sand, etc. to dredged silt to improve soil air permeability and water permeability.

[0072] In one specific embodiment of the present invention, the mass of the improved material blended in the texture improvement = the mass of the dried sludge × (x 目标 -x 实际 )×η;

[0073] Among them, x 目标 is the target value of improved texture of dredged sludge, x 实际 is the actual value of the improved texture of the dredged sludge, and η is the adjusted mixing ratio of the improved material.

[0074] In one specific embodiment of the present invention, n is the adjusted mixing ratio of the improved material, %; β is the correction factor, which is related to the type of sludge and the properties of the improved material; α n It is the nth improved material ratio that increases the quality of dried sludge by Δx per unit, and this value is obtained through experiments.

[0075] In a specific embodiment of the present invention, fertility improvement may be achieved by adding plant straw, livestock and poultry manure organic fertilizer and other materials to the dredged sludge.

[0076] In one specific embodiment of the present invention, the mass of the nutrient material blended in the fertility improvement process = the mass of the dried sludge × (y 目标 -y 实际 )×ξ;

[0077] Among them, y 目标 is the target value of nutrients in dredged sludge, y 实际 is the actual value of nutrients in dredged sludge, and ξ is the adjusted mixing ratio of nutrients.

[0078] In a specific embodiment of the present invention, ξ is the adjustment ratio of nutrients, %; γ is the correction factor, which is related to the type of sludge and the characteristics of organic fertilizer; k n It is the nth organic fertilizer mixing ratio that increases the fertility of each unit of dried sludge by Δy value, and this value is also obtained through experiments.

[0079] In a specific implementation manner of the present invention, the mass ratio of dredged sludge to external admixture is controlled at 5:1 to 4:1.

[0080] In a specific embodiment of the present invention, during soil improvement, the uniformly mixed silt is laid in the planned reclamation area at a designed depth of 25 to 30 cm. During the laying process, the reclamation area is divided into different plots, and clear boundary marks are set for each plot. At the same time, a depth scale is set at the edge of each plot. A laser rangefinder is used to assist in controlling the size, soil cover depth, and field slope of each plot. Then, the surface of the field is gradually leveled by earthwork movement, combined with mechanical loosening operations, to form a high-fertility soil layer suitable for farmland cultivation. In addition, for the farmland reclamation area, field roads with a width of no more than about 3m are reasonably laid out. At the same time, supporting facilities such as irrigation and drainage systems, power transmission and distribution systems, and management and monitoring systems are improved.

[0081] In one embodiment of the present invention, the structure of the farmland reclaimed from dredged sludge obtained in step (5) can be as follows: Figure 2 and 3 As shown, it includes a base backfill layer 1 of the farmland reclamation area, an existing non-backfill area 2, a planned road 3, a farmland cultivation layer 4 and irrigation and drainage supporting equipment 5.

[0082] In a specific embodiment of the present invention, in step (6), selecting suitable crops to be planted according to the soil characteristics of the farmland and the climate conditions is a conventional method in the field of agricultural planting and is not further limited herein.

[0083] In a specific embodiment of the present invention, the soil indicators of the reclaimed farmland monitored in step (7) include moisture content and fertility.

[0084] In a specific embodiment of the present invention, the crop planting indicators of the reclaimed farmland monitored in step (7) include survival rate and growth potential indicators.

[0085] In a specific embodiment of the present invention, fertilization and irrigation are dynamically adjusted according to the monitoring of soil indicators of the cultivated farmland and the crop planting conditions.

[0086] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0087] Example 1

[0088] This embodiment provides a method for dredging silt to reclaim farmland, and its process is as follows: Figure 1 As shown, the processing method includes:

[0089] (1) During the dredging process to improve the water quality of East Lake in Wuhan, dredging machinery was used to excavate the lake bottom silt and transport it to the shore yard. The dredged silt was sampled at intervals after landing to ensure sufficient quantity and different areas, and the basic properties and heavy metal pollutants were measured. The results are shown in Table 2.

[0090] Table 2

[0091]

[0092]

[0093] (2) The dredged mud from the East Lake in Wuhan was evaluated based on the test index results. The results showed that the heavy metal content and biological toxicity of the dredged mud did not exceed the standard, and the salt content and available phosphorus were within the reasonable range, meeting the requirements for agricultural soil utilization.

[0094] (3) Use river and lake bottom mud plate and frame filter press integrated equipment to dehydrate the shore sludge to reduce its water content to below 50%.

[0095] (4) The mechanical strength performance of the dredged mud after dewatering was tested using a cross-plate shear instrument. After the test, its mechanical index was 38 kPa, which meets the requirements for small-scale machinery operation.

[0096] (5) In view of the excessive pH, salt content, phosphorus content and insufficient organic matter content in sludge, river sand, desulfurized gypsum, rice husk and peanut shell organic fertilizer were selected as improvement materials after analysis. River sand can improve the soil particle structure, increase porosity, and effectively reduce the salt and phosphorus content in the soil; desulfurized gypsum can reduce soil pH, improve soil physical and chemical properties, increase water holding capacity, and improve soil permeability and drainage; rice husk can increase soil organic matter content and affect pH; peanut shells are rich in nutrients such as nitrogen, phosphorus and potassium, which have a significant effect on improving soil fertility.

[0097] The target values ​​of pH, salt content, organic matter and phosphorus content of the designed farmland soil are 7.5, 1.0, 63.3 and 15.0 respectively. Through indoor experiments, the adjustment ratios of river sand and desulfurized gypsum in the improved materials for improving unit index parameters are 0.051 and 0.003 respectively; the supplementary ratios of rice husk and peanut shell in the nutrient materials are 0.010 and 0.002 respectively. The amount of texture improvement materials and organic fertilizers required in 100g of dried sludge is calculated according to the formula in the specific implementation, as follows:

[0098] River sand blending mass = 100 × (8.84-7.50) × 0.051 ≈ 6.8

[0099] Desulfurized gypsum blending mass = 100 × (5.8-1.0) × 0.003 ≈ 1.4

[0100] Rice husk blending mass = 100 × (15-5.1) × 0.010 ≈ 10.0

[0101] Peanut shell blending mass = 100 × (63.3-20.0) × 0.002 ≈ 8.2

[0102] The ratio of dried sludge to all added materials is basically 4:1. Then, the dried sludge and added materials are evenly mixed. Figure 4 As shown in the figure, the dried sludge is improved.

[0103] According to the preliminary investigation, planning and design of the farmland reclamation area, the dehydrated dredged sludge containing gravel impurities was used to level the land below the tillage layer. The surface slope below the tillage layer was controlled to be less than 6° by a laser rangefinder. The improved dehydrated sludge was then spread in the tillage layer area of ​​the farmland to be reclaimed. The farmland reclamation area was divided into 5 blocks, each with an area of ​​120m 2 , deep plowing and field leveling operations are carried out, and the thickness of the field cover is verified by the depth ruler within ±3cm, and the internal reclamation of the farmland is completed. Figure 4 .

[0104] After the above process is completed, the roads within the farmland planning area are reasonably laid out and constructed to ensure traffic connections between fields and access within the fields. The road width of the field road is less than 3m. For details, see Figure 5 , and improve the supporting irrigation and drainage systems.

[0105] (6) According to the soil characteristics and climatic conditions of the farmland reclaimed from dredged silt, local spinach, pakchoi and cabbage were selected as test crops in the farmland;

[0106] (7) Through 20 days of continuous monitoring of soil quality and crop growth conditions, the soil moisture condition of the farmland was brown, the germination rate of green vegetables was close to 90%, the germination rate of spinach and cabbage was 80%, and the growth height was about 8 cm. Based on the above-mentioned planting tests and on-site monitoring, all indicators met the requirements for farmland utilization.

[0107] Example 2

[0108] This embodiment provides a method for dredging silt to reclaim farmland, the method comprising:

[0109] (1) During the excavation of the Pinglu Canal channel, the dredged mud was stored in the planned temporary storage yard. Distributed sampling was carried out on the dredged mud to ensure that the storage area was basically covered, and the basic properties of the dredged mud were tested. Since there was no pollution source in the excavation area, the heavy metal and biological toxicity tests were omitted. The results are shown in Table 3.

[0110] Table 3

[0111] Physical and chemical performance testing items Index value Physical and chemical performance testing items Index value Soil Type Silty clay Salt content (g / kg) 3.2 <![CDATA[Heavy (kN / m 3 )]]> 18.7 Hydrolyzable nitrogen (mg / kg) 170 pH 4.58 Available phosphorus (mg / kg) 173 Organic matter (g / kg) 10.3 Available potassium (mg / kg) 195 Liquid limit (%) 40.5 Natural moisture content (%) 68

[0112] (2) Evaluation of the basic properties of dredged sludge is to evaluate the dredged sludge from channel excavation based on the test results. It can be seen that the organic matter and cation exchange capacity of the dredged sludge from the channel are low, the effective nutrients such as available phosphorus and hydrolyzable nitrogen are insufficient, the pH value is low, and it belongs to weakly acidic soil, which requires nutrient supplementation.

[0113] (3) The dredged sludge stored on shore is dehydrated and dried using a plate and frame filter press. The moisture content of the dried dredged sludge is tested to be between 40% and 50%.

[0114] (4) The drop cone test was used to determine the mechanical strength of the dredged sludge after dehydration and drying, and the result showed that its strength was 40 kPa, which was suitable for the construction of small machinery.

[0115] (5) In view of the high viscosity, low organic matter content, low pH value and insufficient hydrolyzable nitrogen nutrients in dredged silt, weathered mudstone particles are selected as texture improvement additives to adjust the pH, improve soil structure, and increase soil permeability and water permeability; cow dung and straw fermented fertilizer are selected as nutrient supplements to increase soil organic matter, supplement soil nitrogen, phosphorus, potassium and other effective nutrients, and promote microbial activity and crop root development.

[0116] The target values ​​of organic matter, pH and hydrolyzable nitrogen in the designed farmland soil are 12, 7.5 and 400 respectively. Through indoor experiments, the adjusted mixing ratios of mudstone, cow dung and straw fermented fertilizer in the improved materials for adjusting the unit index parameters are 0.017, 0.026 and 0.0004 respectively. The amount of texture improvement materials and organic fertilizers required in 100g of dried sludge is calculated according to the formula in the specific implementation, as follows:

[0117] Mudstone blending mass = 100 × (7.50-4.58) × 0.017 ≈ 4.9

[0118] Cow dung mixing mass = 100 × (12-10) × 0.026 ≈ 5.2

[0119] Straw blending mass = 100 × (400-170) × 0.0004 ≈ 9.1

[0120] The ratio of dried dredged sludge to improved material calculated by the above formula is controlled at 5:1, and the dried sludge and improved material are mixed evenly.

[0121] According to the design plan of the farmland construction area, the base backfill layer in the reclamation area was reclaimed and the lower part of the tillage layer was leveled. After the leveling was completed, the farmland in the reclamation area was divided into 4 blocks using a depth scale assisted laser rangefinder. Each block was 100m2 in area. 30cm thick improved dredged silt was laid within the tillage layer. Then the field loosening and field surface leveling operations were carried out. The field surface flatness was controlled at ±4cm to complete the internal reclamation of the farmland.

[0122] After the field reclamation is completed, roads in the farmland area are constructed according to the plan. The field production road is 1.0m wide and is laid out around the farmland. The line is straight and combined with the drainage ditch. The slope of the drainage ditch is 2‰. For irrigation, sprinkler irrigation with a wide coverage is used.

[0123] (6) Based on the soil characteristics and climatic conditions of the farmland reclaimed from dredged silt, sugarcane, corn and potatoes native to the Pinglu Canal were selected as trial crops.

[0124] (7) Through 60-day observation of soil quality and growth conditions, the soil moisture condition was yellow, the survival rate of sugarcane and corn reached about 80%, the growth height was above 20 cm, the survival rate of potatoes was 70%, and the vine growth length was nearly 10 cm. After planting experiments and on-site monitoring, all indicators met the requirements for farmland utilization.

[0125] The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed structural features, that is, it does not mean that the present invention must rely on the above-mentioned detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0126] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0127] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0128] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for dredging silt to reclaim farmland, characterized in that: The processing method comprises: (1) To measure the physical, chemical and biological properties of dredged sludge; (2) conducting a safety assessment of the dredged sludge for farmland use based on the measurement results of step (1); (3) dewatering the dredged sludge to obtain dewatered dredged sludge; (4) performing strength testing on the dewatered dredged sludge in step (3), and reinforcing the dewatered dredged sludge whose strength does not meet the construction requirements; (5) performing farmland reclamation treatment on the dewatered dredged sludge whose strength meets the construction requirements to obtain farmland reclaimed from the dredged sludge; (6) selecting crops to be planted based on the soil properties and climatic conditions of the farmland reclaimed from the dredged sludge in step (5); (7) Monitoring the soil and crop planting conditions of the farmland reclaimed from dredged silt, and evaluating the utilization effect of the farmland reclaimed from dredged silt.

2. The method for reclaiming farmland from dredged sludge according to claim 1, characterized in that: The physical property indicators include soil type, density, particle size, natural moisture content and critical moisture content; and / or, the chemical performance indicators heavy metal content, organic matter content, hydrolyzable nitrogen content, available phosphorus content and available potassium content; And / or, the biological performance index includes a biological toxicity index.

3. The method for reclaiming farmland from dredged sludge according to claim 2, characterized in that: In step (2), the safety of the dredged sludge for farmland utilization is evaluated based on the heavy metal content and biological toxicity indicators.

4. The method for reclaiming farmland from dredged sludge according to claim 1, characterized in that: The dehydration treatment in step (3) includes any one of pressure filtration dehydration, centrifugal separation dehydration, air permeable vacuum rapid mud-water separation or agent solidification dehydration, or a combination of at least two thereof.

5. The method for reclaiming farmland from dredged sludge according to claim 1, characterized in that: The strength test in step (4) uses any one of a falling cone penetrometer, a cross plate shear meter or a flat shovel dilatometer.

6. The method for reclaiming farmland from dredged sludge according to claim 1, characterized in that: The farmland reclamation process in step (5) includes investigation and evaluation, planning and design, land leveling, soil improvement, mechanical soil loosening, field roads and supporting facilities.

7. The method for reclaiming farmland from dredged sludge according to claim 6, characterized in that: The soil improvement includes improving the texture and enhancing the fertility of the dredged sludge.

8. The method for reclaiming farmland from dredged sludge according to claim 7, characterized in that: The mass of the improved material blended in the texture improvement = the mass of dried sludge × (x 目标 -x 实际 )×η; Among them, x 目标 is the target value of improved texture of dredged sludge, x 实际 is the actual value of the improved texture of the dredged sludge, and η is the adjusted mixing ratio of the improved material.

9. The method for reclaiming farmland from dredged sludge according to claim 7, characterized in that: The mass of nutrient materials mixed in the fertility improvement = mass of dried sludge × (y 目标 -y 实际 )×ξ; Among them, y 目标 is the target value of nutrients in dredged sludge, y 实际 is the actual value of nutrients in dredged sludge, and ξ is the adjusted mixing ratio of nutrients.

10. The method for reclaiming farmland from dredged sludge according to claim 1, characterized in that: The soil indicators of the cultivated farmland monitored in step (7) include soil moisture and fertility; And / or, the crop planting indicators of the reclaimed farmland monitored in step (7) include survival rate and growth potential indicators.

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