Preparation of high-organic-matter silt-based ecological restoration spray-seeding substrate and vegetation method

Abstract

The application discloses a kind of high organic matter sludge-based ecological restoration spray seeding substrate preparation and phytogenic method, and spray seeding substrate is mixed and formed by 60%-75% dewatering sludge, 5%-10% ecological curing agent, 3%-5% pretreated straw fiber, 3%-8% broken rice hull and 10%-15% solid waste conditioner with dry mass ratio, and a certain amount of water is additionally added to adjust the substrate slump degree to 170mm-180mm, with early strength characteristics.Planting construction is divided into three times of spray seeding, and the thickness of each spray seeding is 5-7cm, the interval time is not less than 3h, and grass seeds are mixed in the last layer of spray seeding, and a degradable fiber mesh is covered on the surface.The prepared substrate has good fluidity, mechanical strength and phytogenic performance, and can be applied in various slope ecological restoration and greening planting engineering, to realize large-scale collaborative ecological utilization of river and lake sludge and other industrial solid waste materials.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of environmental geotechnical engineering and ecological restoration, and particularly relates to a method for preparing a slope ecological restoration spray-seeding base material from high-organic-content silt. BACKGROUND

[0002] With the comprehensive promotion of river and lake ecological management projects in China, high-organic-content silt (organic content ≥ 8%) produced by dredging projects has become a double challenge for environmental management and resource utilization. This special soil body faces multiple technical barriers in engineering applications: first, its unique colloidal properties result in a significant double electric layer structure, with the Zeta potential on the surface of organic particles generally lower than -30 mV, and a large amount of bound water is adsorbed through electrostatic attraction, forming a stable colloidal system, which makes the soil permeability coefficient as low as 10 -7 ~10 -8 cm / s order, which is difficult to handle by conventional dewatering processes; second, the biochemical activity of organic matter causes a persistent soil degradation effect: in anaerobic / aerobic environments, the degradation of organic matter produces gas-phase products such as CO2 and CH4, causing dynamic evolution of pore structure, and the long-term volume change rate can reach 12%-18%, which seriously threatens the stability of engineering structures; more prominent is that the humus components (humic acid, fulvic acid, etc.) contain a large number of active functional groups (-COOH, -OH), which can form chelation with Ca²⁺, the hydration product of cement, significantly inhibiting the formation of C-S-H gel, so it is difficult to use in engineering by chemical solidification. However, this kind of silt is rich in nutrients such as nitrogen, phosphorus and potassium, and has a suitable carbon-nitrogen ratio (C / N ≈ 15) and cation exchange capacity (CEC ≥ 20 cmol / kg), and its ecological properties are more advantageous than traditional guest soil materials, showing unique resource value in the fields of slope restoration, wetland construction, ecological planting and other ecological engineering. How to overcome its engineering performance defects and realize "waste to treasure" has become a major issue in the field of environmental geotechnical engineering.

[0003] Meanwhile, in the fields of mine restoration and road slope management, the demand for ecological slope protection materials is increasing, and the traditional spray seeding substrate often uses guest soil or cement solidified soil, which has the following technical defects: (1) Poor ecological compatibility of the material: the strong alkalinity (pH>12.5) of the conventional cement-based solidifying agent (such as Portland cement) seriously inhibits the germination and root growth of plant seeds, resulting in insufficient vegetation coverage. (2) Difficult to use high-organic sludge: high-organic sludge has high clay content and strong water retention, and when used directly for spray seeding, it has poor fluidity (slump degree<120mm), easily blocks the pumping equipment, and has low early strength (7d compressive strength<0.2MPa) after solidification, which is easily washed away in the rainy season. (3) Construction efficiency and cost problems: the existing spray seeding process often uses single thick layer spraying (≥10cm), which has high risk of slope collapse due to the large self-weight of the substrate, and needs to be sprayed multiple times, prolonging the construction period by 30%-50%. In addition, the transportation cost of guest soil materials accounts for more than 40% of the total cost of the project, which does not meet the green and low-carbon concept. (4) Insufficient resource utilization of solid waste: the existing technology lacks the collaborative utilization of agricultural waste such as straw and rice husk, and industrial solid waste such as fly ash and slag. Many related patents propose adding straw fibers to the substrate, but the fibers are not modified by alkali treatment, the interface between the fibers and the substrate is weak, the corrosion resistance is poor, and the overall improvement of the tensile strength of the substrate is insufficient.

[0004] In summary, it is urgent to develop a slope repair spray seeding substrate that takes into account low-alkali ecological compatibility, efficient utilization of high-organic sludge, excellent anti-erosion performance, and convenient construction, as well as a matching vegetation process, to break through the current technical bottleneck and promote the collaborative development of sludge resource utilization and ecological restoration. SUMMARY

[0005] The purpose of the present application is to provide a high-organic sludge-based ecological restoration spray seeding substrate preparation and vegetation method to solve the problems of difficult modification and solidification of high-organic sludge, poor mechanical stability, and inability to perform engineering utilization.

[0006] To achieve the above purpose, the technical scheme of the present application is as follows:

[0007] A high-organic sludge-based ecological restoration spray seeding substrate preparation and vegetation method, comprising the following steps:

[0008] S1 Raw material proportioning and pretreatment: including sludge impurity removal and dehydration, ecological solidifying agent preparation, straw fiber pretreatment, rice husk crushing, and solid waste conditioner mixing;

[0009] The sludge dehydration and impurity removal includes removing impurities from the dredged sludge through 5mm screening before dehydration, and then using a plate and frame filter press or a belt filter press for dehydration treatment to a water content of 30%-45%;

[0010] Further, the organic matter content of the sludge is controlled to be 8%-15%, the pH is controlled to be 6.5-7.5, and it is ensured that there is no excessive heavy metal and organic pollutant.

[0011] The low-alkalinity curing agent preparation comprises mixing sulphoaluminate cement clinker, modified phosphogypsum, fly ash, limestone in a mass ratio of 10:(3-4):(2-3):(0.5-1), and the net paste unconfined compressive strength of the mixture after curing for 7 days is higher than 30 MPa, and the pH value is lower than 10.5;

[0012] Further, the modified phosphogypsum comprises calcining phosphogypsum at 150°C for 2 hours to break the crystal water of dihydrate gypsum and improve the activity;

[0013] The straw fiber pretreatment comprises cutting the straw into 5-10 mm short fibers, then soaking in 1% NaOH solution for 2 hours, and finally washing to neutral to improve the fiber-substrate interfacial bonding strength;

[0014] Further, the straw type comprises one or more of corn straw, rice straw and wheat straw;

[0015] The rice hull crushing comprises drying the rice hull at 120°C for 1 hour, and then crushing to a particle size of ≤3 mm to break the surface wax layer to enhance the adsorption;

[0016] The solid waste conditioner mixing comprises mixing one or more of fly ash, waste incinerator slag, sludge incineration ash and biomass ash in any proportion to adjust the substrate gradation and adsorb heavy metals, and the material particle size is controlled to be ≤2 mm.

[0017] Further, the fly ash is grade II, and the heavy metal leaching concentration of the waste incinerator slag is lower than the Standard for Pollution Control on Domestic Waste Landfill Site.

[0018] S2 Preparation of spray-broadcasting substrate: uniformly mixing dehydrated sludge with a dry mass percentage of 60%-75%, ecological curing agent with a dry mass percentage of 5%-10%, pretreated straw fiber with a dry mass percentage of 3%-5%, crushed rice hull with a dry mass percentage of 3%-8%, and solid waste conditioner with a dry mass percentage of 10%-15% to obtain a mixture;

[0019] Further, a certain amount of water is added to the mixture, and the mixture is stirred until the slump degree reaches 170-180 mm to form a pumpable spray-broadcasting substrate;

[0020] Further, the amount of water added is controlled by the slump degree of the substrate, and the water is added in three times, 50% of the first time (to activate the curing agent), 30% of the second time (to adjust the fiber dispersibility), and 20% of the last time (to accurately adjust the slump degree).

[0021] S3 Substrate spray construction: the substrate described in S2 is sprayed onto the slope surface by a wet spray machine in three times, each time with a thickness of 5-7cm, and the interval time is not less than 3h (to ensure the initial setting support of the lower layer), and the plant seeds are mixed synchronously in the last spraying;

[0022] Further, the mixed grass seeds include multiple kinds of tall fescue, Bermuda grass, bahia grass, Amorpha fruticosa and white clover, and the seeding amount is 20-30g / m 2 .

[0023] S4 Substrate maintenance: after the spray construction, a degradable fiber mesh is covered on the surface of the substrate, and then regular watering is carried out for maintenance, and the maintenance period is 6 months.

[0024] As preferred, the unconfined compressive strength of the high-organic-matter silt slope ecological restoration spray substrate obtained by the present application is 0.15-0.30MPa, the pH value is lower than 10.5, the 1h scouring mass loss rate is ≤15%, and the plant seed germination rate is ≥80% after 7d maintenance.

[0025] One or more technical solutions provided in the present application have the following technical effects or advantages:

[0026] 1. The ecological compatibility is improved, the present application uses sulphoaluminate cement clinker (pH 9.5-10.5) to replace the traditional Portland cement (pH>12), and the pH value of the substrate is controlled below 10.5 by combining the acid neutralization of modified phosphogypsum and the later alkali consumption reaction of limestone powder, so that the plant growth environment is significantly improved.

[0027] 2. Efficient utilization of silt and solid waste resources, the dehydrated silt in the spray substrate accounts for 60%-75%, which breaks through the limitation of the silt content (usually ≤50%) of the traditional solidified material, realizes the on-site disposal of river and lake sludge, and greatly reduces the cost of silt filling and silt filling by about 80%. In addition, the solid waste conditioner (fly ash, slag, etc.) accounts for ≥10%, the total utilization rate of industrial solid waste is increased to more than 80%, and the material cost and environmental hazards are reduced.

[0028] 3. Mechanical properties and erosion resistance are optimized, and the reaction of sulphoaluminate clinker and modified phosphogypsum generates ettringite (AFt) and C-S-H gel, with 7d unconfined compressive strength of 0.30~0.45MPa, significant early strength characteristics, and no decay of late strength, which can be used on 45°~85° high and steep slopes, meeting the requirements of short-term stability of the slope (NB / T 35082-2016 requires ≥0.38MPa). In addition, pretreated straw fibers (3%~5%) form a three-dimensional reinforced network, and broken rice husks (3%~8%) store water and gas through pores, both of which synergistically improve the tensile strength by 25%~30%, and the erosion mass loss rate is ≤15%.

[0029] 4. Construction efficiency and long-term stability are improved: the present technology is sprayed in three times (5~7cm each time, with 3h interval), avoiding the collapse problem of single thick layer spraying. The low alkalinity ecological solidifying agent used in the present invention has significant early strength characteristics (final setting time of 3~4h), so the interval of each layer spraying can be only 3h, greatly improving the construction efficiency.

[0030] 5. The present invention realizes the efficient combination of high-organic sludge resource utilization and slope ecological restoration through the innovation of low-alkali solidifying agent material, solid waste synergistic utilization and layered spraying process. The sprayed base material prepared by the present invention is low in cost, low in carbon and environmentally friendly, and has good mechanical stability and plant growth effect, while realizing the nearby utilization of river and lake sludge. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is the preparation flowchart of the high-organic sludge prepared slope ecological restoration sprayed base material of the present invention.

[0032] Figure 2 is the pot planting test effect diagram of Example 1 of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the present invention clearer and more intelligible, the present invention is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present invention and do not limit the present invention.

[0034] The present invention provides a high-organic sludge-based ecological restoration sprayed base material preparation and plant growth method, which solves or partially solves the problem of high-organic sludge resource utilization, and realizes the synergistic utilization of multiple solid wastes. The prepared ecological restoration sprayed base material has the technical advantages of high utilization rate of industrial solid waste (>80%), strong resistance to rainwater erosion (7d compressive strength of 0.3~0.45MPa), and high construction efficiency (one layer can be sprayed every 3h), is suitable for high and steep slope ecological restoration engineering, has low cost, can realize the large-scale nearby utilization of river and lake sludge, and achieves the beneficial effects of economic benefit and ecological environmental benefit.

[0035] Referring to the drawings Figure 1 The application provides a preparation and vegetation method of a high-organic-matter silt-based ecological restoration spray-seeding substrate.

[0036] S1 raw material proportioning and pretreatment: specifically including silt impurity removal and dewatering, ecological curing agent preparation, straw fiber pretreatment, rice husk crushing and solid waste conditioner mixing.

[0037] The silt dewatering and impurity removal comprises removing impurities from dredged silt through 5 mm screening before dewatering, and then adopting a plate-and-frame filter press or a belt filter press for dewatering treatment to a water content of 30% to 45%.

[0038] The silt has an organic matter content of 8% to 15%, a pH of 6.5 to 7.5, and no heavy metals and organic pollutants exceeding the standard.

[0039] The low-alkalinity curing agent preparation comprises fully mixing sulphoaluminate cement clinker, modified phosphogypsum, fly ash and limestone at a mass ratio of 10:(3 to 4):(2 to 3):(0.5 to 1), and the net paste unconfined compressive strength of the curing agent after curing for 7 days is higher than 30 MPa, and the pH value is lower than 10.5.

[0040] In the application, the sulphoaluminate cement clinker (pH 9.5 to 10.5) is used to replace the traditional Portland cement (pH > 12), the acid neutralization of the modified phosphogypsum and the later alkali consumption reaction of the limestone powder are combined, and the pH value of the substrate is controlled to be below 10.5, so that the plant growth environment is significantly improved. The acid neutralization of the sulphoaluminate cement clinker, the modified phosphogypsum and the later alkali consumption reaction of the limestone powder are as follows:

[0041] C4A3Š+3CH+3CaCO3+36H2O→C6AŠ3H32 (AFt)+C3A2ĈH6 (C-A-Ĉ-H)

[0042] +2Al(OH)3 (AH)

[0043] The modified phosphogypsum comprises calcining phosphogypsum at 150 ℃ for 2 hours to break the dihydrate gypsum crystal water and improve the activity.

[0044] The straw fiber pretreatment comprises cutting the straw into 5 to 10 mm short fibers first, then soaking in a 1% NaOH solution for 2 hours, and finally washing to neutral to improve the fiber-substrate interfacial bonding strength.

[0045] Further, the straw type comprises one or more of corn straw, rice straw and wheat straw.

[0046] The rice hull crushing includes drying the rice hull at 120 DEG C for 1 hour and then crushing to a particle size of less than or equal to 3 mm, so as to break the surface wax layer to enhance the adsorption.

[0047] The solid waste conditioner mixing includes mixing one or more of fly ash, waste incinerator slag, sludge incineration ash, and biomass ash in any proportion, for adjusting the base material gradation and adsorbing heavy metals, and controlling the material particle size to be less than or equal to 2 mm.

[0048] The fly ash is grade II, and the heavy metal leaching concentration of the waste incinerator slag is lower than the Standard for Pollution Control on Domestic Waste Landfill Site.

[0049] S2: Preparation of the spray-broadcast base material: uniformly mix 60%-75% of the dehydrated sludge, 5%-10% of the ecological curing agent, 3%-5% of the pretreated straw fiber, 3%-8% of the crushed rice hull, and 10%-15% of the solid waste conditioner, to obtain a mixture.

[0050] Add a certain amount of water to the mixture, and stir until the slump degree reaches 170-180 mm, to form a pumpable spray-broadcast base material.

[0051] The amount of water added is controlled by the slump degree of the base material, and the water is added in three times, 50% of the first time (to activate the curing agent), 30% of the second time (to adjust the fiber dispersibility), and 20% of the last time (to precisely adjust the slump degree).

[0052] S3: Construction of the spray-broadcast base material: spray the base material of S2 to the slope surface through a wet spray-broadcast machine in three times, and the spray-broadcast thickness of each time is 5-7 cm, and the interval time is not less than 3 h (to ensure the initial setting support of the lower layer), and the plant seeds are mixed simultaneously in the last spray-broadcast.

[0053] The mixed grass seeds include multiple kinds of tall fescue, kikuyu grass, bahia grass, amsonia, and white clover, and the seeding amount is 20-30 g / m 2 .

[0054] S4: Maintenance of the base material: cover the base material surface with a degradable fiber mesh after the spray-broadcast construction, and then regularly water the base material for maintenance, and the maintenance period is 6 months.

[0055] Preferably, the spray-broadcast base material for ecological restoration of the high-organic-content sludge slope obtained by the present application has a unconfined compressive strength of 0.15 MPa-0.30 MPa, a pH value of less than 10.5, a 1 h scouring mass loss rate of less than or equal to 15%, and a plant seed germination rate of greater than or equal to 80% after 7 d of maintenance.

[0056] The specific implementation is as follows:

[0057] The mud for the example test was taken from the Gongtang Reservoir in Zhongxiang City, Hubei Province, and the basic physicochemical property indexes of the mud were as follows: the mud was used to carry out a preparation of a spray seeding base material and a pot planting test, and three groups of parallel pot planting test samples were arranged for each example;

[0058] Example

[0059] S1 raw material ratio and pretreatment, specifically including the following:

[0060] (1) The river and lake mud was passed through a 5 mm sieve, and then the water content was adjusted to 42.3%;

[0061] (2) The preparation of the low alkalinity solidifying agent included fully mixing sulphoaluminate cement clinker, modified phosphogypsum, fly ash, and limestone at a mass ratio of 10:3.5:2.5:0.5, and the net paste unconfined compressive strength of the solidifying agent after curing for 7 days was higher than 32.3 MPa, and the pH value was 10.3;

[0062] (3) The straw fiber was corn straw, which was cut into 5-10 mm short fibers, then soaked in a 1% NaOH solution for 2 hours, and finally washed to neutral to improve the fiber-base material interfacial bonding strength;

[0063] (4) The rice husk was first dried at 120°C for 1 hour, and then broken to a particle size of ≤3 mm to break the surface wax layer to enhance the adsorption;

[0064] (5) The solid waste conditioner was selected to be a waste incinerator slag, and was passed through a 2 mm sieve.

[0065] S2 Preparation of the spray seeding base material: 72% dewatered sludge, 3% ecological solidifying agent, 5% pretreated straw fiber, 5% broken rice husk, and 15% waste incinerator slag were mixed, and then a certain amount of water was added, and fully stirred until the slump reached 175.3 mm, forming a pumpable spray seeding base material.

[0066] S3 Base material spray seeding planting test: the prepared base material was sprayed into the planting pots using a small mud spraying equipment, and was sprayed three times with an interval of 3 hours each time, and a certain amount of tall fescue seeds was mixed into the base material during the last spraying, and the mixing ratio was 6 g / pot.

[0067] S4 Base material curing: the pots containing the spray seeding base material were placed in a balcony with good lighting conditions for curing, and a certain amount of water was sprayed regularly for curing, Figure 2 is the pot planting test effect picture of Example 1.

[0068] Test analysis: on the one hand, the germination rate and growth speed of the seeds in the pots were recorded, such as Figure 2The biomass of the plants in each pot was tested at 30 d of maintenance. On the other hand, the bulk density, porosity, unconfined compressive strength and pH value of the substrate at 7 d of maintenance were tested and analyzed, and the test standard referred to the Standard for Soil Test Methods (GB / T 50123-2019) Example 1

[0069] In this example, the substrate components include 69% dewatered sludge, 6% ecological stabilizer, 5% pretreated straw fiber, 5% broken rice husk and 15% waste incinerator slag in dry mass percentage, then a certain amount of water is added, and fully stirred until the slump reaches 178.2 mm to form a pumpable spray seeding substrate.

[0070] The types of other raw materials, treatment methods, test conditions and test contents are the same as those in Example 1. Example 2

[0071] In this example, the substrate components include 66% dewatered sludge, 9% ecological stabilizer, 5% pretreated straw fiber, 5% broken rice husk and 15% waste incinerator slag in dry mass percentage, then a certain amount of water is added, and fully stirred until the slump reaches 172.5 mm to form a pumpable spray seeding substrate.

[0072] The types of other raw materials, treatment methods, test conditions and test contents are the same as those in Example 1. Example 3

[0073] In this example, the substrate components include 63% dewatered sludge, 12% ecological stabilizer, 5% pretreated straw fiber, 5% broken rice husk and 15% solid waste conditioner in dry mass percentage, then a certain amount of water is added, and fully stirred until the slump reaches 172.1 mm to form a pumpable spray seeding substrate.

[0074] The types of other raw materials, treatment methods, test conditions and test contents are the same as those in Example 1. Example 4

[0075] In this example, the substrate components include 79% dewatered sludge, 6% ecological stabilizer, 5% pretreated straw fiber, 5% broken rice husk and 5% waste incinerator slag in dry mass percentage, then a certain amount of water is added, and fully stirred until the slump reaches 178.6 mm to form a pumpable spray seeding substrate.

[0076] The types of other raw materials, treatment methods, test conditions and test contents are the same as those in Example 1. Example 5

[0077] The substrate component in this example includes 74% dewatered sludge, 6% ecological curing agent, 5% pretreated straw fiber, 5% broken rice husk and 10% waste incinerator slag by dry mass percentage, then a certain amount of water is added, and fully stirred until the slump reaches 176.4 mm to form a pumpable spray seeding substrate.

[0078] The other raw material types, treatment methods, test conditions and test contents are the same as those of Example 1.

[0079] The test results of the indicators of each example are as follows:

[0080]

[0081] From the above test results, it can be seen that as the low-alkalinity ecological curing agent in the substrate increases from 3% to 12% (Examples 1-4), the germination rate, growth height and biomass of the plants in the spray seeding substrate all show a trend of first increasing and then decreasing. When the ecological curing agent content is 6%-9%, the plant growth is optimal, and the plant germination rate can reach more than 85%. In addition, as the low-alkalinity ecological curing agent gradually increases in the range of 3%-12%, the bulk density, pH and unconfined compressive strength of the substrate after 7 days of curing are gradually increased in the ranges of 1.45-1.53 g / cm 3 , 10.01-10.42 and 53.5-316.2 kPa, respectively. It can be seen that the pH value of the substrate is less than 10.5, which meets the needs of conventional plant growth. When the low-alkalinity curing agent is 12% (Example 4), the unconfined compressive strength of the substrate after 7 days of curing can reach 356 kPa, which affects the germination and growth of plants due to the high strength of the substrate.

[0082] As can be seen from Comparative Examples 2, 5 and 6, as the content of solid waste conditioner (waste incinerator slag) increases from 5% to 15%, the plant germination rate and growth rate gradually increase, and the plant germination and growth are optimal when the content of solid waste conditioner is 10%-15%. This is mainly because when the content of solid waste conditioner is low, the porosity of the substrate is small, which is not conducive to the respiration and growth of plant roots. In addition, as the content of solid waste conditioner increases, the unconfined compressive strength of the substrate also increases, which is because the waste incinerator slag contains part of active SiO2 and Al2O3, which can participate in the hydration reaction, thereby improving the strength of the substrate.

[0083] In summary, the high organic matter sludge preparation slope ecological restoration spray seeding substrate provided by the application has good ecological performance, on the one hand, the substrate has good mechanical stability, and on the other hand, the substrate can well meet the germination and growth of plants, can be popularized and applied in various high and steep slope ecological restoration projects, realizes the large-scale collaborative utilization of river and lake sludge and other solid waste materials, solves the problem of resource utilization of high-organic-content river and lake sludge, is expected to form a new ecological restoration mode of turning waste into green, and has good economic value and ecological environment benefits.

[0084] Finally, it should be noted that: the content not described in detail in the specification belongs to the prior art known to those skilled in the art, and the above description is only for the preferred embodiments of the application and is not used to limit the application, although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or make equivalent replacement for part of the technical features. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A method for preparing and growing a high organic matter sludge-based ecological restoration spray seeding substrate, characterized in that, The method comprises the following steps: S1: uniformly mixing dewatered sludge, ecological curing agent, pretreated straw fiber, broken rice husk and solid waste conditioner according to the dry material mass percentage to obtain a mixture, wherein the allocation ratio of each component is: dewatered sludge: 60%-75%; ecological curing agent: 6%-9%; pretreated straw fiber: 3%-5%; broken rice husk: 3%-8%; solid waste conditioner: 10%-15%; wherein the organic matter content of the dewatered sludge is controlled to be 8%-15%; the ecological curing agent comprises sulphoaluminate cement clinker, modified phosphogypsum, fly ash and limestone mixed according to a mass ratio of 10:3.5:2.5:0.5, the net paste unconfined compressive strength of the ecological curing agent is higher than 32.3 MPa after curing for 7 days, and the pH value is 10.3; the modified phosphogypsum comprises calcining phosphogypsum at 150°C for 2 hours to break the crystal water of dihydrate gypsum; the pretreated straw fiber comprises cutting straw into 5-10 mm short fibers, then soaking in 1% NaOH solution for 2 hours, and finally washing to neutral; the broken rice husk comprises drying rice husk at 120°C for 1 hour, and then breaking to a particle size of ≤3 mm to break the surface wax layer; the unconfined compressive strength of the ecological restoration spray-seeding base material of the high-organic-matter sludge slope after curing for 7 days is 0.15 MPa-0.30 MPa, the pH value is lower than 10.5, the 1h scouring mass loss rate is ≤15%, and the plant seed germination rate is ≥80%; S2: adding water to the mixture in S1 and stirring until the slump reaches 170 mm-180 mm to form a pumpable spray-seeding base material; S3: spraying the base material in S2 to the slope surface through a wet spray-seeding machine in batches, the spraying thickness of each time is 5-7 cm, the interval time is not less than 3 hours, and plant seeds are mixed synchronously in the last spraying, and a degradable fiber net is covered on the surface.

2. The method according to claim 1, wherein the method is characterized by: The dewatered sludge is passed through a 5 mm sieve before dewatering, and the dewatering of the dewatered sludge comprises dewatering dredged sludge by using a plate and frame filter press or a belt filter press to a water content of 30%-45%.

3. The method according to claim 1, wherein the method is characterized by: The straw type comprises one or more of corn straw, rice straw and wheat straw.

4. The method according to claim 1, wherein the method is characterized by: The solid waste conditioner comprises one or more of fly ash, waste incinerator slag, sludge incineration ash and biomass ash, and the particle size is ≤2 mm.

5. The method of claim 1, wherein the method is characterized by: The water is added in three times in the S2 step, and the adding weight is controlled by the base material slump, the first time adding water is 50%, the second time adding water is 30%, and the last time adding water is 20%.

6. The method of claim 1, wherein the method is characterized by: The plant seeds include one or more of tall fescue, Bermudagrass, Bahia grass, Amorpha fruticosa, white clover, and the seeding amount is 20-30 g / m 2 .

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