Method for preparing regenerated planting soil by compounding sludge and hydrothermal carbon with muck and application of regenerated planting soil

Abstract

The invention belongs to the technical field of soil improvement and solid waste resource utilization, and provides a method for preparing regenerated planting soil by compounding sludge hydrothermal carbon with muck and application, and the regenerated planting soil is prepared by preparing hydrothermal carbon from sludge and compounding engineering muck, the sludge hydrothermal carbon, a fungicide and an organic material. The mass ratio of the optimized engineering residue soil to the sludge hydrothermal carbon to the microbial inoculum to the organic material is 7: 0.5: 2.5, preparation of the regenerated planting soil can be completed within 10 days, the parameters of the obtained regenerated planting soil are that the pH value is 7.17, the organic matter content is 31.30 g / kg, the hydrolytic nitrogen content is 769.35 mg / kg, the available phosphorus content is 113.36 mg / kg, the available potassium content is 505.16 mg / kg, and the related requirements of the CJ / T340 planting soil standard are met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of soil improvement and solid waste resource utilization, and provides a method and application of preparing regenerated planting soil from sludge hydrochar and compound slag soil. BACKGROUND

[0002] With the advancement of urbanization, the production of engineering slag and municipal sludge is increasing year by year. Engineering slag, as the main component of construction waste, accounts for 70% of construction waste. The slag generally has poor air permeability, weak water retention capacity, and lacks organic matter and nutrients, and is difficult to meet the growth needs of plants when directly used for vegetation planting. The common disposal and utilization methods currently include stacking, backfilling, building material products, and roadbed fillers, which have limitations such as land resource occupation, low market acceptance, high cost, material and construction control difficulties, and low overall resource utilization rate. It cannot meet the current large-scale disposal of slag, and the soil resource is wasted seriously, and the structural defects of the slag cannot be fundamentally solved.

[0003] On the other hand, municipal sludge is rich in nutrients such as nitrogen, phosphorus, and organic matter, but also contains harmful substances such as heavy metals, pathogenic bacteria, and persistent organic pollutants. Improper disposal can cause soil and groundwater pollution. In existing sludge treatment technologies, landfilling occupies land and is prone to leachate risks, incineration has high energy consumption and may release toxic gases, and composting has long composting cycles and limited heavy metal passivation effects. In recent years, hydrochar technology has been widely concerned as a new solid waste treatment method. It can convert wet sludge into hydrochar rich in humus and developed pore structure, while inactivating pathogenic bacteria and stabilizing heavy metals.

[0004] Currently, there is no mature process for applying sludge hydrochar to engineering slag improvement, and there is a lack of systematic solutions for the synergistic effect of the two in existing technologies, especially in the optimization of hydrochar preparation parameters, the design of slag and hydrochar ratio, and the performance control of improved planting soil, which limits the efficiency and safety of solid waste resource utilization. SUMMARY

[0005] The purpose of the present application is to provide a method and application of preparing regenerated planting soil from sludge hydrochar and compound slag soil to solve the problems of poor physical and chemical properties of engineering slag, lack of nutrients for direct planting, and environmental risks caused by improper disposal of municipal sludge.

[0006] The application discloses a method for preparing regenerated planting soil from sludge hydrochar and engineering slag, and aims at solving the problem of high-value effective resource utilization of engineering slag.

[0007] To solve the problems in the prior art, the application adopts the technical scheme that The application provides a method for preparing regenerated planting soil from sludge hydrochar and engineering slag, which comprises the following steps: 1) The sludge hydrochar is prepared by using a high-pressure reaction kettle, and the process parameters are as follows: the temperature rising rate of the reaction kettle is 5-10 DEG C / min, the reaction temperature is 180-250 DEG C (corresponding to the self-born pressure of 2-6 MPa), the reaction time is 0.5-4 h, and after pressure relief at the end of the reaction, the water content is adjusted to 30%-50% by mass to prepare the sludge hydrochar; 2) The engineering slag is crushed and sieved, and the size of the sieve is 10 mesh; 3) The engineering slag, the barley waste residue, the pig farm biogas slurry, the rice straw and the sludge hydrochar are mixed in a mass ratio of 70:10%-30%:10%-20%:5:0 or 5 to obtain engineering slag containing organic materials; 4) The compound bacteria powder is added into the engineering slag containing organic materials, and the total mass of the compound bacteria powder is 1‰-4‰; 5) The initial water content of the mixed sludge hydrochar, the engineering slag, the bacteria agent and the organic materials is controlled to be 45%-60%, and then the mixture is placed in a reactor to be fermented and matured in an aerobic and light-avoiding environment, the heating zone temperature is 45 DEG C, the soil fermentation and maturation time is 10 days, and the regenerated planting soil is prepared.

[0008] Further, in the step 3), the sludge hydrochar, the engineering slag, the bacteria agent and the organic materials are preferably mixed in a mass ratio of 70% engineering slag, 10% barley waste residue, 10% pig farm biogas slurry, 5% rice straw and 5% sludge hydrochar.

[0009] Further, in the step 4), the compound bacteria powder is composed of Bacillus subtilis powder and Aspergillus niger powder in a mass ratio of 5:4, and the strain concentration of the Bacillus subtilis powder and the Aspergillus niger powder is greater than or equal to 1*10 9 CFU / g.

[0010] The application further provides the regenerated planting soil prepared by the method, and the pH of the planting soil is 7.40-7.17, the hydrolytic nitrogen is 714.57-832.04 mg / kg, the effective phosphorus is 107.65-139.04 mg / kg, the available potassium is 380.55-505.16 mg / kg, and the organic matter is 21.72-32.58 g / kg.

[0011] The application further provides application of the regenerated planting soil in promoting growth of tomatoes.

[0012] The application has the following beneficial effects: 1) The application utilizes the porous structure of the sludge hydrochar to improve the air permeability and water retention of the residue, and the nutrient elements carried by the sludge hydrochar can improve the soil fertility, and the water heat conversion process can effectively reduce the bioavailability of pathogenic bacteria and heavy metals in the sludge, avoid secondary pollution, and realize the recycling economic goal of "waste treatment by waste".

[0013] 2) The application uses engineering residue as raw material, and barley waste residue, pig farm biogas slurry and rice straw and other organic materials as auxiliary materials, which provides a new solution path for the country to solve the difficult utilization of engineering residue, and realizes the virtuous cycle of turning waste into treasure of local organic waste materials. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 Effect diagram of the regenerated planting soil added with different materials on the growth promotion of tomatoes; Figure 2 Influence result diagram of the planting soil of different treatments on the growth indexes of tomatoes, wherein a diagram is the influence result diagram on the plant height of tomatoes, b diagram is the influence result diagram on the stem thickness of tomatoes, c diagram is the influence result diagram on the leaf number of tomatoes, d diagram is the influence result diagram on the leaf area of tomatoes, and d diagram is the influence result diagram on the root tip number of tomatoes. DETAILED DESCRIPTION

[0015] The strains used in the application are purchased from Beina Biology, and the strains can also be directly purchased from CGMCC Company, and the preservation numbers are as follows: Bacillus subtilis preservation number is CGMCC NO.1.6757, and Aspergillus niger preservation number is CGMCC NO.3.17612.

[0016] The preparation methods of the Bacillus subtilis bacterial powder and the Aspergillus niger bacterial powder used in the following examples are as follows: Take 0.1 g of Bacillus subtilis and Aspergillus niger freeze-dried powder respectively, inoculate into LB solid medium (Bacillus subtilis) and PDA solid medium (Aspergillus niger) respectively, incubate Bacillus subtilis at 37°C for 24 h, and incubate Aspergillus niger at 28°C for 7 d, until single colonies grow, pick single colonies with regular morphology and transfer to corresponding slant medium, incubate Bacillus subtilis slant for 24 h until it is covered with bacterial lawn, and incubate Aspergillus niger slant until it is covered with green spores, to obtain activated strains; scrape the above-mentioned slant activated strains and inoculate into corresponding liquid seed culture medium respectively, shake culture Bacillus subtilis seed liquid at 37°C and 180 r / min for 12 h, shake culture Aspergillus niger seed liquid at 28°C and 150 r / min for 36 h, until the OD 600 value of the bacterial liquid reaches 0.8-1.0, to prepare seed liquid; inoculate Bacillus subtilis seed liquid and Aspergillus niger seed liquid into fermentation tank medium respectively at a 5% (v / v) inoculation amount, the fermentation conditions of Bacillus subtilis are 37°C, 180 r / min and aeration amount 1:1.2 (vvm) for 24 h, and the fermentation conditions of Aspergillus niger are 28°C, 150 r / min and aeration amount 1:1.0 (vvm) for 7 d, until the viable bacterial count in the fermentation liquid is ≥1×10 9 CFU / mL, stop fermentation; centrifuge the fermentation liquid at 4°C and 8000 r / min for 15 min to collect bacterial precipitate; place the bacterial precipitate in a vacuum freeze dryer, dry at -45°C and a vacuum degree of 10 Pa for 12 h until the water content of the bacterial precipitate is ≤5%, put the dried bacterial precipitate into a universal crusher, crush and pass through an 80-mesh sieve, to obtain Bacillus subtilis powder and Aspergillus niger powder.

[0017] Example 1 Optimization of the amount of organic material added.

[0018] The sludge hydrothermal carbon is prepared by using a high-pressure reaction kettle, and the preparation process parameters are as follows: the heating rate of the reaction kettle is 5-10 ℃ / min, the reaction temperature is 180-250 ℃ (corresponding to the self-generated pressure of 2-6 MPa), the reaction time is 0.5-4 h, and the moisture content of the sludge hydrothermal carbon is adjusted to 30%-50% after pressure relief. The engineering muck is collected from the foundation pit of road engineering construction in Jiaxing, Zhejiang, and the sampling depth is 3-6 meters underground. The soil sample is a silty (sandy) loam soil with a pH value of 7.96, and the organic matter and nitrogen, phosphorus and potassium nutrients are all low (as shown in Table 1). The engineering muck is crushed to remove residual plants and rocks through a 10-mesh sieve. The organic materials used in the experiment are obtained and pretreated as follows: the rice straw is collected from a rice field, cut into 1-2 cm particles and used; the barley manure is obtained from a beer production plant, and the pig farm biogas slurry is directly extracted from a storage tank after pig manure fermentation. All raw materials are not subjected to other chemical or physical modification treatment to ensure the originality and accuracy of the subsequent experiment.

[0019] Four different proportions of organic material additions are set according to the mass ratio, and the mass ratio of each component is as follows: T1: 70% engineering muck, 20% barley manure, 10% pig farm biogas slurry; T2: 70% engineering muck, 25% barley waste, 5% rice straw; T3: 70% engineering muck, 10% barley waste, 15% pig farm biogas slurry, 5% rice straw; T4: 70% engineering muck, 10% barley waste, 10% pig farm biogas slurry, 5% rice straw, 5% sludge hydrothermal carbon.

[0020] Then, the compound bacteria powder (mass ratio of bacillus subtilis powder to aspergillus niger powder = 5:4) is added to T1, T2, T3 and T4, respectively, and the addition amount of the compound bacteria powder is 2‰ of the total mass of the engineering muck containing organic materials, and the bacteria powder concentration is ≥1×10 9 CFU / g. After being mixed thoroughly, the moisture content is controlled to about 50%, and then the fermentation and curing are carried out in an aerobic and light-proof device, the temperature of the heating zone is set to 45 ℃, the fermentation and curing time is 10 days, and the regenerated planting soil is prepared. The temperature change of the pile body is monitored regularly every day to explore the influence of different material additions on the improvement and curing of the muck and the nutrient indicators of the regenerated planting soil.

[0021] Practice has proved that the addition amount of the compound bacteria powder in the range of 1‰-4‰ of the total mass of the engineering muck containing organic materials can achieve good results.

[0022] The results show that after maturation, the physicochemical properties of T1, T2, T3, T4 groups and the engineering slag without adding organic material are determined, including pH, hydrolytic nitrogen, available phosphorus, available potassium, organic matter, and the results are shown in Table 1. It is found that the nitrogen, phosphorus, potassium and organic matter content of the soil are significantly improved, which meets the requirements of the relevant standards. Table 1 Comparison of physicochemical properties after adding different materials for maturation treatment

[0023] Example 2 The application of the prepared regenerated planting soil in tomato growth is prepared according to the method in Example 1, and 5 groups of regenerated planting soil are prepared, which are control group CK, i.e. the engineering slag is crushed to 10 mesh sieve, and the residual plants and rocks are removed, T1, T2, T3, T4 in Example 1, each group has 4 repetitions. The prepared regenerated planting soil of each group is respectively filled into the seedling pots with consistent specifications, and the amount of soil filled in each pot is up to 1 cm from the pot opening, and the 2-week-old tomato seedlings with healthy growth and consistent height are selected for single transplantation. After transplantation, it is placed in an artificial incubator with temperature control of 25±2℃, light for 12h / day, and the cultivation mode of watering once a day (the watering amount is up to the bottom of the pot just penetrated) is adopted, and the growth conditions of tomato seedlings after 4 weeks of transplantation are observed (Table 2) Figure 1 ), and the data of plant height, stem diameter, leaf number, leaf area, and root tip number of each group of tomatoes are recorded (Table 3) Figure 2 ). The result data show that the growth of tomatoes treated with different materials is better than that of the CK control group, and the sludge hydrochar addition treatment group (T4) is significantly different (P<0.05) from all other groups in stem diameter, leaf number, and root tip number, and the plant height and fresh weight are also significantly better than those of CK and T2 groups, which indicates that the promotion effect of T4 on the growth of tomato seedlings (stem and leaf development) and root development has statistical reliability.

[0024] It should be noted that the engineering slag and organic material described above are only one source collected by the present application, but they are not intended to limit the present application. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, any technical solution obtained by replacing the source of slag or the source of organic material falls within the protection scope of the present application.

Claims

1. A method for preparing recycled planting soil from sludge hydrothermal carbon composite slag soil, characterized in that, Includes the following steps: 1) Prepare sludge hydrothermal carbon using a high-pressure reactor. The process parameters are: reactor heating rate 5-10℃ / min, reaction temperature 180-250℃ or autogenous pressure 2-6Mpa, reaction time 0.5-4h, and after depressurization at the end of the reaction, dehydrate and adjust the moisture content to 30%-50% by mass to obtain sludge hydrothermal carbon. 2) After crushing the construction waste, sieve it and chop the straw into 1-2cm pieces for later use; 3) Add 70% engineering waste soil, 10%-30% barley waste residue, 10%-20% pig farm biogas slurry, 5% rice straw, and 0 or 5% sludge hydrothermal carbon by mass to obtain engineering waste soil containing organic materials. 4) Add 1‰ to 4‰ of the total mass of compound bacterial powder to the engineering waste containing organic materials; 5) After the initial moisture content of the mixed sludge hydrothermal carbon, slag, microbial agent and organic materials is controlled at 45%-60%, it is placed in a reactor and fermented and matured in an aerobic and light-protected environment. The heating zone temperature is 45℃ and the soil fermentation and maturation time is 10 days to prepare recycled planting soil.

2. The method according to claim 1, characterized in that, In step 2), the sieve is 10 mesh.

3. The method according to claim 1, characterized in that, In step 3), the preferred mass ratio is: 70% engineering waste soil, 10% barley waste residue, 10% pig farm biogas slurry, 5% rice straw, and 5% sludge hydrothermal charcoal.

4. The method according to claim 1, characterized in that, In step 4), the compound bacterial powder consists of Bacillus subtilis powder and Aspergillus niger powder in a mass ratio of 5:4, wherein the bacterial concentration of both Bacillus subtilis powder and Aspergillus niger powder is ≥1×10⁻⁶. 9 CFU / g.

5. A regenerated planting soil prepared according to the method of claims 1-4.

6. The recycled planting soil according to claim 5, characterized in that, The planting soil parameters are: pH 7.40~7.17, hydrolyzable nitrogen 714.57~832.04 mg / kg, available phosphorus 107.65~139.04 mg / kg, available potassium 380.55~505.16 mg / kg, and organic matter 21.72~32.58 g / kg.

7. The use of the regenerated planting soil according to any one of claims 5-6 in promoting tomato growth.

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