Method for preparing planting soil from gravel sewage mud cake and application

Abstract

The invention relates to the technical field of environmental protection, and particularly discloses a method for preparing planting soil from artificial gravel sewage mud cakes and application of the planting soil. During treatment, the mud cakes are crushed, mixed with quick lime and aged for 7 days or above; and adding sulfur powder, an organic fertilizer and magnesium sulfate into the obtained material, and mixing to obtain the planting soil. The mud cake is treated, the pH value of the mud cake is reduced, the cation exchange capacity of the mud cake is improved, the non-capillary porosity is reduced, and the content of medium trace elements is adjusted, so that the mud cake can be suitable for landscaping planting soil.

Description

Technical Field

[0001] The invention relates to the technical field of environmental protection, and in particular to a method for preparing planting soil by utilizing sandstone sewage mud cake and application thereof. Background Art

[0002] During construction, some civil engineering materials need to be washed according to the site conditions. The washing process will produce a large amount of wastewater. During the purification and sedimentation process, the wastewater will form solid sediment - mud cake. Due to the high treatment cost and environmental risks, it has always been a difficult problem in engineering construction.

[0003] Traditionally, mud cakes are usually landfilled, which takes up a lot of land resources and may pollute the environment and groundwater. How to effectively utilize mud cakes is an urgent problem to be solved.

[0004] CN112794678A discloses a method for recycling mud cakes after separation of mud and sand from construction waste soil, wherein the mud cakes are crushed and then treated with improvers such as peat soil, urea, zeolite powder, biological agents, phosphoric acid, river sand and water to obtain soil that can be used for landscaping. The construction waste soil is the mud cake obtained after separation of mud and sand, and the mud cake itself has similar properties to natural soil. The addition of various improvers is only to improve the fertility of the mud cake, and no measures are taken for the pH value, heavy metals, porosity, etc. of the mud cake. Summary of the invention

[0005] The present invention provides a method for preparing planting soil by utilizing sandstone sewage mud cake and application thereof, which can effectively utilize the sandstone sewage mud cake and the prepared planting soil has more advantages for the growth of crops than ordinary soil.

[0006] The technical solution of the present invention is to provide a method for preparing planting soil using sandstone sewage mud cake, comprising the following steps: S1, mixing mud cake with quicklime and aging for more than 7 days; S2. Add sulfur powder, organic fertilizer and magnesium sulfate to the material obtained in S1, mix them, and obtain planting soil.

[0007] Optionally, the mud cake is a solid phase sediment of sand and gravel aggregate washing wastewater. During the sand and gravel aggregate washing process, the rock powder produced by mechanically crushing the stone will enter the washing water. Finally, the mud cake produced by flocculation and filtration in the purification system is essentially different from the soil. The solid phase sediment mud cake of sand and gravel aggregate washing wastewater has a high pH and is alkaline, and the cation exchange capacity and magnesium content are low, the copper content is high, and the non-capillary porosity is high, and it cannot be directly used as planting soil. Measures need to be taken to adjust organic matter, pH, porosity, fertility, heavy metal content, etc.

[0008] Optionally, the amount of quicklime added is 1 / 5000 to 1 / 5500 of the mud cake mass.

[0009] Optionally, the added amount of the sulfur powder is 1 / 25000 to 1 / 27000 of the mass of the mud cake.

[0010] Optionally, the organic matter content in the organic fertilizer is ≥40%, and the amount of organic fertilizer added is 1 / 200 times the mass of the mud cake.

[0011] Optionally, the amount of magnesium sulfate added is 1 / 20000 of the mass of the mud cake.

[0012] Optionally, in S2, when the organic fertilizer is added, one or more of biochar, zeolite, bentonite, and humic acid are also added.

[0013] Optionally, when processing the mud cake, it is directly spread on the area to be planted for processing, with a spreading thickness of 30-180 cm. When other materials are added, deep plowing and mixing are performed.

[0014] The present invention also relates to the application of the planting soil prepared by the method in gardening and greening planting.

[0015] Optionally, the plants planted for landscaping are poinciana, bougainvillea, creeper and / or bermudagrass.

[0016] The present invention has the following beneficial effects: When the present invention treats the mud cake, quicklime is first added for treatment to reduce the effective copper content in the mud cake. During the treatment process, aging is required so that the quicklime can be fully mixed with the mud cake, and the effective state content of heavy metals in the soil is reduced by adsorption and complexation, thereby reducing its toxic effect on plants. Then sulfur powder, organic fertilizer and magnesium sulfate are added, wherein sulfur powder can reduce the pH value of the mud cake to meet the requirements of planting soil. By adding organic fertilizer, on the one hand, the fertilizer effect of the mud cake can be further increased. At the same time, one or more of biochar, zeolite, bentonite and humic acid can be added to synergistically improve the cation exchange capacity of the mud cake, increase the soil organic matter content, promote the formation of soil aggregates, thereby reducing non-capillary porosity; and by adding magnesium sulfate, the magnesium content of the mud cake is adjusted to meet the requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The mud cake which has not been processed by the present invention is used for the growth of flowers and creepers after 100 days of planting.

[0018] Figure 2 The growth conditions of flowers and creepers planted with the planting soil obtained in the example after 100 days. DETAILED DESCRIPTION

[0019] The experimental methods in the following examples are conventional methods unless otherwise specified. The raw materials, reagents, etc. used in the following examples are commercially available products unless otherwise specified.

[0020] The present invention provides a method for preparing planting soil by using sandstone sewage mud cake, comprising the following steps: S1, mixing mud cake with quicklime and aging for more than 7 days; S2. Add sulfur powder, organic fertilizer and magnesium sulfate to the material obtained in S1, mix them, and obtain planting soil.

[0021] Optionally, the mud cake is a solid phase sediment of sand and gravel aggregate washing wastewater. The pH of the solid phase sediment mud cake of sand and gravel aggregate washing wastewater is high and alkaline, and the cation exchange capacity and magnesium content are low, the copper content is high, and the non-capillary porosity is high, so it cannot be directly used as planting soil.

[0022] The mud cakes in the following examples and comparative examples come from the large-scale water conservancy project construction process, which produces a large amount of wastewater when washing construction materials such as sand and gravel, specifically solid phase sediments formed during the purification process of wastewater. Sampling was tested according to the CJ / T340-2016 "Greening Planting Soil" standard, and the following problems were found in Table 1.

[0023] Table 1

[0024] Heavy metal content: Level II, which meets the heavy metal content requirements for planting soil in green spaces such as botanical gardens, parks, schools, and residential areas where people are in close contact with nature. It also meets the requirements for planting soil in forest land such as road green belts, factory-affiliated green spaces, abandoned mines, and contaminated soil remediation that are lower than Level II.

[0025] The present invention is described in detail below in conjunction with specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0026] Example 1 1) Spread the mud cake on the greening construction site where backfill planting soil is required; 2) Add 75g / ㎡ of quicklime (purity ≥99%) to the mud cake, turn it 30cm deep, and let it stand for 7 days; 3) Spread 15g / ㎡ sulfur powder (purity ≥99%), 2kg / ㎡ biological organic fertilizer (organic matter ≥40%), and 20g / ㎡ magnesium sulfate (purity ≥98%); 4) Deep plowing should be no less than 30cm according to the needs of garden plant planting.

[0027] Example 2 1) Spread the mud cake on the greening construction site where backfill planting soil is required; 2) Add 75g / ㎡ of quicklime (purity ≥99%) to the mud cake, turn it 30cm deep, and let it stand for 7 days; 3) Spread 15g / ㎡ sulfur powder (purity ≥99%), 2kg / ㎡ bio-organic fertilizer (organic matter ≥40%), 2000g / ㎡ biochar, 5g / ㎡ bentonite and 20g / ㎡ magnesium sulfate (purity ≥98%); 4) Deep plowing should be no less than 30cm according to the needs of garden plant planting.

[0028] Example 3 In step 3), 2000 g / m2 of biochar was also added when adding organic fertilizer, and the rest was the same as step 1.

[0029] Example 4 In step 3), 5 g / m2 of bentonite was also added when adding organic fertilizer, and the rest was the same as step 1.

[0030] The planting soil obtained by the above embodiment was tested according to the CJ / T340-2016 "Greening Planting Soil" standard, and the specific situation is shown in Table 2 below.

[0031] Table 2

[0032] Field trials: Improved group, control group I and control group II were set up for field control experiments. The experimental implementation steps of each group are as follows: Improved group: The planting soil obtained in Example 1 was used for the test Control group I: pure mud cake experimental field (mud cake was not improved), deep plowing.

[0033] Control group II: ordinary planting soil test field, deep plowing.

[0034] Plant cultivation In each experimental group, representative plants such as trees, shrubs, and herbs were planted. The same species of plants, including royal poinciana, bougainvillea, spatholobi, and bermudagrass, were planted in each experimental field. The planting distribution is shown in Table 3.

[0035] Table 3

[0036] Plant growth statistics The plants planted in each experimental field were maintained under the same conditions. After growing in the field for 3 months, the field growth values ​​such as plant height, crown width, and flowering amount were recorded according to the characteristics of different plants, and statistical comparisons were made (see Table 4).

[0037] Table 4

[0038] Field experiment conclusion The improved mud cake is used as the planting soil for poinciana, bougainvillea, philadelphus and bermudagrass. Compared with the ordinary planting soil, the growth condition is good, the field growth deviation is higher than -20%, and it has a significant growth-promoting effect. Therefore, the improvement plan is feasible. It is especially suitable for the planting of bougainvillea and philadelphus.

[0039] like Figure 1 and Figure 2 The figures show the growth of untreated mud cake and the planting soil of Example 1 after 100 days of planting. It can be seen that the mud cake directly used for planting soil has no obvious growth after planting, while the planting soil of Example 1 grows well.

[0040] The above embodiments describe the preferred implementation of the present invention, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing planting soil using sandstone sewage cake, characterized in that: The following steps are involved: S1, crush the mud cake, mix it with quicklime, and age it for more than 7 days; S2. Add sulfur powder, organic fertilizer and magnesium sulfate to the material obtained in S1, mix them, and obtain planting soil.

2. The method according to claim 1, characterized in that: The mud cake is a solid phase sediment of sand and gravel aggregate washing wastewater.

3. The method according to claim 1, characterized in that: The amount of quicklime added is 1 / 5000 to 1 / 5500 of the mud cake mass.

4. The method according to claim 1, characterized in that: The added amount of the sulfur powder is 1 / 25000 to 1 / 27000 of the mud cake mass.

5. The method according to claim 1, characterized in that: The organic matter content in organic fertilizer is ≥40%, and the amount of organic fertilizer added is 1 / 200 of the mud cake mass.

6. The method according to claim 1, characterized in that: The amount of magnesium sulfate added is 1 / 20000 of the mud cake mass.

7. The method according to any one of claims 1 to 6, characterized in that: In S2, when the organic fertilizer is added, one or more of biochar, zeolite, bentonite and humic acid are also added.

8. The method according to any one of claims 1 to 6, characterized in that: When processing the mud cake, spread it directly on the area to be planted for treatment. The spreading thickness is 30~180cm. When adding other materials, deep plowing and mixing are carried out.

9. Use of the planting soil prepared by the method according to any one of claims 1 to 8 in landscaping planting.

10. The use according to claim 9, characterized in that: Plants planted for landscaping are poinciana, bougainvillea, philadelphus and / or bermudagrass.

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