A method for preparing ditch filling material for road drainage purification and nourishment

Abstract

The invention discloses a preparation method of a ditch filling material for road drainage purification and nourishment, wherein medical stone is crushed and sequentially added into a calcium chloride solution and a sodium silicate solution for soaking treatment, washed and dried and then heat-treated to obtain modified medical stone; agricultural waste is made into activated carbon; iron tailings sand is ground and sterilized to make a microbial culture medium, inoculated with sulfur-reducing Geobacter and metal-reducing Geobacter and then cultured for 5-7 days to obtain a hybrid substance containing ferrous iron, which is uniformly mixed with modified medical stone, apatite, activated carbon and fine sand, and 15%-25% of water is added and stirred to obtain. Compared with the prior art, the ditch filling material can not only efficiently adsorb and remove organic and inorganic pollutants in road water through redox reaction on the basis of fully meeting drainage needs, but also release phosphorus in the water body, effectively slow down the diffusion of pollutants, significantly reduce the negative impact on the natural environment, and promote the growth and development of roadside vegetation.

Description

Technical Field

[0001] The invention belongs to the technical field of road water purification, and in particular relates to a method for preparing a ditch filling material used for road drainage purification and nourishment. Background Art

[0002] As an important part of urban infrastructure, the original design of traditional road drainage system is mainly to quickly and effectively drain water such as rainfall, car wash wastewater, road runoff from the road surface to prevent water accumulation on the road and ensure smooth traffic. However, this direct discharge treatment method ignores various pollutants that may be carried in the water, such as heavy metal ions (such as lead, cadmium, copper, etc.), oils and greases, acid and alkali substances, suspended particulate matter, and some soluble organic matter. These pollutants are directly discharged into natural water bodies such as ditches, rivers, and lakes without treatment, which not only pollutes the water quality and destroys the balance of aquatic ecosystems, but may also accumulate through the food chain, posing a potential threat to human health.

[0003] In recent years, China has made significant progress in the research of road drainage purification materials. In response to the problems of urban waterlogging and runoff pollution caused by the increase in impervious areas during urbanization, researchers have begun to pay attention to the application of porous or permeable paving materials. This type of material has high permeability and can effectively reduce surface runoff, delay peak time and alleviate urban waterlogging. Permeable pavement also has a certain purification function and can remove some pollutants in runoff. In order to further improve its purification effect, domestic scholars have explored the application of a variety of additives, such as zeolite powder, fly ash, diatomaceous earth, etc., but the purification effect is still not particularly ideal.

[0004] Internationally, the research on road drainage purification materials has also attracted much attention. Scholars from various countries have conducted in-depth research on different types of permeable paving materials and developed a variety of innovative purification technologies. Similar to China, foreign countries also attach importance to the role of additives in improving the purification performance of permeable pavement. For example, some studies have explored the application of new additives such as nanomaterials and biochar in permeable concrete, and found that these materials can improve the removal of pollutants such as organic pollutants, heavy metals and nutrients to a certain extent. However, the purification capacity of these repair materials still cannot achieve a completely ideal effect, and the purified accumulated water will always have an impact on the vegetation on both sides of the road.

[0005] On the other hand, with the continuous development of economy and the acceleration of industrialization, the scale of steel industry is expanding, resulting in the annual increase of solid wastes such as scrap iron and slag. If these tailings and scrap iron are properly handled and utilized, they can not only help alleviate the problem of resource shortage, but also reduce environmental pollution and promote the development of circular economy.

[0006] If tailings and scrap iron produced in industrial activities can be reused and used in road drainage systems, it will be a win-win move. In view of this, it is particularly urgent and significant to develop a new technology that uses medical stone and iron tailings to further optimize the removal efficiency of pollutants and promote the healthy growth and development of vegetation along the road. Summary of the invention

[0007] The purpose of the present invention is to provide a method for preparing a ditch filling material for road drainage purification and nourishment, in view of the current situation that the existing road drainage system is unable to treat road surface water polluted by heavy metals (exhaust gas), oil pollution, acidity (acid rain), etc., and direct discharge may cause pollution of the woodland, grassland, or cultivated soil around the road. The prepared ditch filling material integrates multiple purification mechanisms such as physical adsorption, chemical precipitation and biological promotion, and can efficiently remove heavy metals, oil pollution and other harmful substances in water bodies. At the same time, it has a unique pore structure and component composition, which can provide a good attachment and reproduction environment for microorganisms, promote the biodegradation process, and further improve the water purification effect.

[0008] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0009] A method for preparing a ditch filling material for road drainage purification and nourishment comprises the following steps:

[0010] Step S1. Crush the medical stone into 80 mesh powder, then soak it in a calcium chloride solution, take it out, wash it and dry it, then soak it in a sodium silicate solution, take it out after the end, wash it and dry it, and finally heat treat it to obtain modified medical stone;

[0011] Step S2. The agricultural waste is dried and crushed, and then placed in a low-temperature sintering furnace, sintered at 650-750°C for 8-10 hours, cooled after sintering, and ground into 80 meshes to obtain activated carbon;

[0012] Step S3. After cleaning the iron tailings, grind them to 80 meshes, sterilize them, mix them with lactic acid, phosphate buffer, trace element solution, and gypsum to prepare a microbial culture medium, inoculate them with Geobacter sulfurreducens and Geobacter metalreducens, and then culture them in an anaerobic box for 5-7 days. After solid-liquid separation, dry them to obtain a hybrid substance containing ferrous iron;

[0013] Step S4. The modified medical stone, apatite, activated carbon, fine sand and ferrous hybrid material are mixed uniformly to obtain a mixture, and water accounting for 15%-25% of the mass of the mixture is added and stirred uniformly to obtain a ditch filling material for road drainage purification and nourishment;

[0014] In step S2, the agricultural waste is rice husk, corn stalks or sugarcane bagasse.

[0015] Furthermore, in step S1, the concentration of the calcium chloride solution is 2-4 mol / L, and the soaking time in the calcium chloride solution is 20-26 hours.

[0016] Furthermore, in step S1, the concentration of the sodium silicate solution is 1.5-2.5 mol / L, and the soaking time in the sodium silicate solution is 20-26 hours.

[0017] Furthermore, in step S1, the heat treatment is carried out at a temperature of 320-350° C. and for a duration of 0.5-1.5 hours.

[0018] Further, in step S3, in step S3, the formula of the microbial culture medium is: 10 g / L iron tailings, 20 mM lactic acid, 0.5 mM phosphate buffer with pH = 7.0, 1 mL / L trace element solution, and 1 g / L gypsum; the trace element solution contains 1 mg / L copper sulfate, 1 mg / L zinc sulfate, 1 mg / L manganese sulfate and 1 mg / L nickel sulfate.

[0019] Further, in step S4, the mass ratio of the modified medical stone, apatite, activated carbon, fine sand and ferrous hybrid material is (20-25):(3-5):(10-15):(40-55):(2-5).

[0020] Furthermore, in step S4, the particle size of the fine sand and apatite is less than 0.25 mm.

[0021] Beneficial effects of the present invention: The present invention provides a method for preparing a ditch filling material for road drainage purification and nourishment, aiming to reduce and purify pollutants in road drainage from the backflow process. The filling material is carefully designed to integrate multiple purification mechanisms such as physical adsorption, chemical precipitation and biological promotion, and can efficiently remove harmful substances such as heavy metals and oil pollution in the water body. At the same time, its unique pore structure and component composition provide a good attachment and reproduction environment for microorganisms, promote the biodegradation process, and further improve the water purification effect. Compared with the prior art, the ditch filling material of the present invention can not only efficiently adsorb and remove organic and inorganic pollutants in road water through oxidation-reduction on the basis of fully meeting the drainage needs, but also release phosphorus in the water body, which effectively slows down the spread of pollutants, significantly reduces the negative impact on the natural environment, and further promotes the growth and development of roadside vegetation. At the same time, the iron ore tailings are reused, achieving the dual benefits of environmental protection and ecology, and has broad application prospects in road drainage systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Test results of plant coverage around the road for ditch fill;

[0023] Figure 2 It is the test result of permeability coefficient of ditch filling material;

[0024] Figure 3 These are the test results for phosphorus content in road water. DETAILED DESCRIPTION

[0025] The embodiments of the present invention are described in further detail below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the embodiments.

[0026] In the following examples, the Geobacter sulfurreducens and Geobacter metalloreducens used were purchased from Beijing Biological Collection Center; the iron tailings used were from Lianyungang Port Group.

[0027] Example 1

[0028] A method for preparing a ditch filling material for road drainage purification and nourishment comprises the following steps:

[0029] Step S1. crushing the medical stone into 80 mesh powder, then adding it to a 3 mol / L calcium chloride solution and soaking it for 24 hours, taking it out and washing and drying it, adding it to a 1 mol / L sodium silicate solution and soaking it for 24 hours, taking it out and washing it, drying it at 140°C for 11 hours, placing it in a high temperature furnace, heating it to 340°C and heat treating it for 1 hour to obtain modified medical stone;

[0030] Step S2. The corn stalks are dried and crushed, and then placed in a low-temperature sintering furnace, sintered at 700°C for 9 hours, cooled after sintering, and ground into 80 meshes to obtain activated carbon;

[0031] Step S3. After cleaning the iron tailings, grind them to 80 meshes and sterilize them at 121° C. for 30 minutes; prepare a microbial culture medium according to the ratio of iron tailings (10 g / L), lactic acid (20 mM), phosphate buffer (0.5 mM, pH=7.0), trace element solution (1 mL / L), and gypsum (1 g / L), wherein the trace element solution contains 1 mg / L copper sulfate, 1 mg / L zinc sulfate, 1 mg / L manganese sulfate, and 1 mg / L nickel sulfate; inoculate sulfur-reducing Geobacter and metal-reducing Geobacter (the ratio of the two strains is 1:1) into the microbial culture medium, and after culturing in an anaerobic box for 7 days, use a filter membrane to separate the ferrous iron-containing substance in the culture medium, and after drying, obtain a ferrous iron-containing hybrid substance;

[0032] Step S4. Crush apatite and fine sand to control the particle size below 0.25 mm; then mix the modified medical stone, apatite, activated carbon, fine sand and ferrous hybrid material in a mass ratio of 25:5:15:40:5 to obtain a mixture, add water accounting for 15% of the mass of the mixture, stir evenly, and obtain a ditch filling material for road drainage purification and nourishment.

[0033] Example 2

[0034] A method for preparing a ditch filling material for road drainage purification and nourishment comprises the following steps:

[0035] Step S1. crush the medical stone into 80 mesh powder, then add it to a 3 mol / L calcium chloride solution and soak it for 24 hours, take it out and wash and dry it, then add it to a 1 mol / L sodium silicate solution and soak it for 24 hours, take it out and wash it and dry it at 140°C for 11 hours, place it in a high temperature furnace, heat it to 340°C for 1 hour, and obtain modified medical stone;

[0036] Step S2. The corn stalks are dried and crushed, and then placed in a low-temperature sintering furnace, sintered at 700°C for 9 hours, cooled after sintering, and ground into 80 meshes to obtain activated carbon;

[0037] Step S3. After cleaning the iron tailings, grind them to 80 meshes and sterilize them at 121° C. for 30 minutes; prepare a microbial culture medium according to the ratio of iron tailings (10 g / L), lactic acid (20 mM), phosphate buffer (0.5 mM, pH=7.0), trace element solution (1 mL / L), and gypsum (1 g / L), wherein the trace element solution contains 1 mg / L copper sulfate, 1 mg / L zinc sulfate, 1 mg / L manganese sulfate, and 1 mg / L nickel sulfate; inoculate sulfur-reducing Geobacter and metal-reducing Geobacter (the ratio of the two strains is 1:1) into the microbial culture medium, and after culturing in an anaerobic box for 7 days, use a filter membrane to separate the ferrous iron-containing substance in the culture medium, and after drying, obtain a ferrous iron-containing hybrid substance;

[0038] Step S4. Crush apatite and fine sand to control the particle size below 0.25 mm; then mix the modified medical stone, apatite, activated carbon, fine sand and ferrous hybrid material in a mass ratio of 22:3:15:55:5 to obtain a mixture, add water accounting for 20% of the mass of the mixture, stir evenly, and obtain a ditch filling material for road drainage purification and nourishment.

[0039] Comparative Example 1

[0040] A method for preparing a ditch filling material for road drainage purification comprises the following steps:

[0041] Step S1. calcine the zeolite in a high temperature furnace at 800°C, grind and sieve to 80 mesh powder, and dry;

[0042] Step S2. The corn stalks are dried and crushed, and then placed in a low-temperature sintering furnace, sintered at 700°C for 9 hours, cooled after sintering, and ground into 80 meshes to obtain activated carbon;

[0043] Step S3. Crush apatite and fine sand to control the particle size below 0.25 mm; then mix zeolite, apatite, activated carbon and fine sand in a mass ratio of 25:5:15:55 to obtain a mixture, add water accounting for 20% of the mass of the mixture, stir evenly, and obtain a ditch filling material for road drainage purification.

[0044] Application testing:

[0045] Representative plots were selected on both sides of the road, and a 10m long section was selected as the test site. The plot area was set to 10×20m 2 , record basic information such as vegetation type, quantity, height, and coverage, and lay the side ditch filling material prepared in Example 1 in the side ditch foundation pit on both sides of the road. The foundation pit width is 0.8m and the laying thickness is 30cm; select the adjacent road section and lay the side ditch filling material prepared in Example 2 and Comparative Example 1 in the same way. After laying, compaction treatment is carried out and curing is carried out for 28 days under the conditions of keeping moist, avoiding high temperature, and avoiding disturbance. One month after laying, the vegetation in the sample plot is observed, and the coverage rate is calculated using the vertical projection area of ​​the vegetation according to the projection area method and other methods. According to the method of constant head infiltration experiment in the geotechnical test method standard (GB-T 50123-2019), a stable infiltration device is constructed, the water head of the water source is kept constant, the amount of seepage water passing through the filling material per unit time is measured, and the permeability coefficient is calculated. During and after the curing period, the changes in the content of phosphorus in the filling material and its surrounding environment are continuously monitored, including the phosphorus content in the soil, water body, and vegetation. The pH of deionized water is adjusted to 5.6 by adding hydrochloric acid, and used to simulate rainwater or groundwater to leach the filler. The leaching solution is collected and the concentration of phosphorus in the leaching solution is regularly detected using a spectrophotometer according to the method provided in GB 11893-89.

[0046] Figure 1 The test results of plant coverage around the ditch filling road are as follows: Figure 1 It can be seen that the vegetation coverage rate of the road using the ditch filling materials prepared by Examples 1 and 2 of the present invention is significantly higher than that of Comparative Example 1.

[0047] Figure 2 is the test result of permeability coefficient of ditch filling material, Figure 2 It can be seen that compared with comparative example 1, the permeability coefficient of the ditch filling materials prepared in examples 1 and 2 of the present invention is reduced, but it is also beneficial to control the diffusion and repair of pollutants.

[0048] Figure 3 The test results of phosphorus content in road water are as follows: Figure 3It can be seen that after using the ditch filling materials prepared by Examples 1 and 2 of the present invention, as the number of flushing days increases, the phosphorus content contained in the road water also increases continuously, and the content is significantly higher than that in Comparative Example 1.

Claims

1. A method for preparing a ditch filling material for road drainage purification and nourishment, characterized in that: The steps include: Step S1. Crush the medical stone into 80 mesh powder, then soak it in a calcium chloride solution, take it out, wash it and dry it, then soak it in a sodium silicate solution, take it out after the end, wash it and dry it, and finally heat treat it to obtain modified medical stone; Step S2. The agricultural waste is dried and crushed, and then placed in a low-temperature sintering furnace, sintered at 650-750°C for 8-10 hours, cooled after sintering, and ground into 80 meshes to obtain activated carbon; Step S3. After cleaning the iron tailings, grind them to 80 meshes, sterilize them, mix them with lactic acid, phosphate buffer, trace element solution, and gypsum to prepare a microbial culture medium, inoculate them with Geobacter sulfurreducens and Geobacter metalreducens, and then culture them in an anaerobic box for 5-7 days. After solid-liquid separation, dry them to obtain a hybrid substance containing ferrous iron; Step S4. The modified medical stone, apatite, activated carbon, fine sand and ferrous hybrid material are mixed uniformly to obtain a mixture, 15%-25% of water by mass of the mixture is added, and stirred uniformly to obtain a ditch filling material for road drainage purification and nourishment; In step S2, the agricultural waste is rice husk, corn stalk or sugarcane bagasse; In step S1, the heat treatment temperature is 320-350°C and the duration is 0.5-1.5 hours; In step S4, the mass ratio of the modified medical stone, apatite, activated carbon, fine sand and ferrous hybrid material is (20-25):(3-5):(10-15):(40-55):(2-5).

2. The method for preparing the ditch filling material for road drainage purification and nourishment as claimed in claim 1, characterized in that: In step S1, the concentration of the calcium chloride solution is 2-4 mol / L, and the soaking time in the calcium chloride solution is 20-26 hours.

3. The method for preparing the ditch filling material for road drainage purification and nourishment as claimed in claim 1, characterized in that: In step S1, the concentration of the sodium silicate solution is 1.5-2.5 mol / L, and the soaking time in the sodium silicate solution is 20-26 hours.

4. The method for preparing the ditch filling material for road drainage purification and nourishment as claimed in claim 1, characterized in that: In step S3, the formula of the microbial culture medium is: 10 g / L iron tailings, 20 mM lactic acid, 0.5 mM phosphate buffer with pH = 7.0, 1 mL / L trace element solution, and 1 g / L gypsum; the trace element solution contains 1 mg / L copper sulfate, 1 mg / L zinc sulfate, 1 mg / L manganese sulfate and 1 mg / L nickel sulfate.

5. The method for preparing the ditch filling material for road drainage purification and nourishment according to any one of claims 1 to 4, characterized in that: In step S4, the particle size of the fine sand and apatite is less than 0.25 mm.

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