Method and system for synergistically preparing humus soil from urban building slurry and garden waste

Abstract

The invention relates to the technical field of solid waste resource utilization, in particular to a method and system for synergistically preparing humus soil from urban building slurry and garden waste, and the method comprises the following steps: S1, pretreating the building slurry with the water content of 80-90% and the PH value through a multi-stage separation system to obtain gravel / cement particles and colloidal particles; s2, adding a curing agent into the obtained colloidal particles to carry out curing dehydration; s3, adding a compound microbial agent, garden waste and a modifier into the dehydrated colloidal particles obtained in the step S2, mixing, adjusting the moisture content of the mixture to 45-55% and the C / N ratio to 25-30, and then fermenting; through a multi-stage separation-solidification dehydration-microbial fermentation full-chain process, collaborative recycling of the building mud and the garden waste is achieved. Gravels and cement particles in the building slurry are separated into concrete aggregate, colloidal particles and garden waste are fermented into humus soil, the comprehensive utilization rate of solid waste is larger than 95%, and the problem of resource waste caused by traditional landfill treatment is solved.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, specifically to a method and system for co-preparing humus from urban construction mud and garden waste. Background Technology

[0002] Urban construction mud is a high-moisture solid waste generated during construction, containing gravel, cement particles, and heavy metal / organic pollutants. Traditional landfill disposal methods not only occupy land resources but also easily cause soil and groundwater pollution. Existing treatment technologies have drawbacks such as low separation efficiency, high heavy metal residues, and low added value of products. Furthermore, they have not achieved co-treatment with organic solid wastes such as garden waste, and resource utilization needs to be improved.

[0003] Therefore, a method for co-preparing humus from urban construction mud and garden waste is needed to improve the above-mentioned problems. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for co-preparing humus from urban construction mud and garden waste, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for co-preparing humus from urban construction mud and garden waste includes the following steps: S1: Pre-treat the construction mud with a moisture content of 80-90% and a pH value through a multi-stage separation system to obtain gravel / cement microparticles and colloidal microparticles; S2: Add a curing agent to the obtained colloidal particles to cure and dehydrate them; S3: Add the dehydrated colloidal microparticles obtained in step S2 to the compound microbial agent, garden waste and amendment, and mix them. Adjust the moisture content of the mixture to 45-55% and the C / N ratio to 25-30, and then carry out fermentation. S4: Add a passivating agent to the fermented mixture to fix heavy metals and remove organic pollutants to obtain humus soil. S5: The humus soil is piled up in the dark at 25-30℃ for 15 days and turned over intermittently. After the pile is finished, it is passed through a 4mm sieve to remove undegraded impurities and obtain the final product of humus soil.

[0006] As a preferred embodiment of the present invention, the composite microbial agent comprises Bacillus subtilis, Aspergillus niger, and actinomycetes in a ratio of 5:3:2.

[0007] As a preferred embodiment of the present invention, the modifier includes bentonite and humic acid in a ratio of 7:3.

[0008] As a preferred embodiment of the present invention, the multi-stage separation system includes a first-stage magnetic separation, a second-stage eddy current separation, and a third-stage hydrocyclone, which are respectively performed using a magnetic separator, an eddy current separator, and a hydrocyclone.

[0009] As a preferred embodiment of the present invention, the gravel particles separated by the three-stage hydrocyclone have a particle size >2mm, and the cement microparticles have a particle size of 0.05-2mm.

[0010] As a preferred embodiment of the present invention, the curing agent added in step S2 includes polyaluminum chloride and quicklime, and the amount of polyaluminum chloride is 5-8 kg / ton of mud, and the amount of quicklime is 3-5 kg / ton of mud.

[0011] As a preferred embodiment of the present invention, step S2 involves dewatering by plate and frame filter press with a pressure of 1.5-2.0 MPa and a time of 30 min.

[0012] As a preferred embodiment of the present invention, in step S3, the proportion of dehydrated colloidal microparticles is 60-70 wt%, the proportion of compound microbial agent is 0.5-1.0 wt%, the proportion of improver is 5-10 wt%, and the proportion of garden waste is 20-30 wt%, wherein the garden waste is plant branches and leaves.

[0013] As a preferred embodiment of the present invention, the fermentation temperature of the mixture in step S3 is 55-65℃, the fermentation time is ≥7 days, and the mixture is turned over once every 48 hours during the fermentation process.

[0014] As a preferred embodiment of the present invention, the passivating agent comprises 200-mesh zero-valent iron powder, potassium persulfate and chitosan, and the addition ratio is 1-2:0.5:0.3 (wt%).

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention achieves the synergistic resource utilization of construction mud and garden waste through a multi-stage separation-solidification dehydration-microbial fermentation process. Gravel and cement particles in the construction mud are separated into concrete aggregates, while colloidal particles and garden waste are fermented into humus. The comprehensive utilization rate of solid waste is >95%, solving the resource waste problem caused by traditional landfill disposal. This invention employs a composite microbial agent to target and degrade organic pollutants, while simultaneously immobilizing heavy metals using an iron-based organic composite passivating agent, achieving dual purification through organic degradation and heavy metal solidification. The heavy metal solidification rate is ≥95% (Pb and Cd leaching concentrations ≤0.1 mg / L and 0.01 mg / L, respectively; formaldehyde degradation rate >99%), effectively blocking pollutant migration pathways. In the process of this invention, construction mud is transformed into high-value humus, and garden waste is reduced and recycled. The cost per ton of treatment is low, and the economic value added of the product covers more than 120% of the treatment cost, making it valuable for industrialization and promotion. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the reaction mechanism of zero-valent iron in this invention. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0018] To facilitate understanding of the present invention, a more complete description will be given below with reference to relevant descriptions. Several embodiments of the invention are provided. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0019] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Example

[0021] A method for co-preparing humus from urban construction mud and garden waste includes the following steps: S1: Pre-treat the construction mud with a moisture content of 80-90% and a pH value through a multi-stage separation system to obtain gravel / cement microparticles and colloidal microparticles; S2: Add a curing agent to the obtained colloidal particles to cure and dehydrate them; S3: Add the dehydrated colloidal microparticles obtained in step S2 to the compound microbial agent, garden waste and amendment, and mix them. Adjust the moisture content of the mixture to 45-55% and the C / N ratio to 25-30, and then carry out fermentation. S4: Add a passivating agent to the fermented mixture to fix heavy metals and remove organic pollutants to obtain humus soil. S5: The humus soil is piled up in the dark at 25-30℃ for 15 days and turned over intermittently. After the pile is finished, it is passed through a 4mm sieve to remove undegraded impurities and obtain the final product of humus soil.

[0022] The compound microbial agent contains Bacillus subtilis, Aspergillus niger, and actinomycetes in a ratio of 5:3:2. The modifiers include bentonite and humic acid in a ratio of 7:3.

[0023] The multi-stage separation system includes a first-stage magnetic separation, a second-stage eddy current separation, and a third-stage hydrocyclone, which are respectively carried out by a magnetic separator, an eddy current separator, and a hydrocyclone. Primary magnetic separation: A magnetic separator with a magnetic field strength ≥1.2T is used to remove magnetic impurities such as reinforcing bars, with a removal rate >99%; Two-stage eddy current separation: Using an eddy current separator with a frequency of 50-60Hz, non-magnetic lightweight impurities such as plastics are separated with a separation efficiency of ≥95%; The gravel separated by the three-stage hydrocyclone has a particle size >2mm, and the cement microparticles have a particle size of 0.05-2mm.

[0024] The curing agents added in step S2 include polyaluminum chloride and quicklime, with the amount of polyaluminum chloride being 6 kg / ton of slurry and the amount of quicklime being 4 kg / ton of slurry. Step S2 involves dewatering by plate and frame filter press with a pressure of 1.5-2.0 MPa and a time of 30 min.

[0025] In step S3, the proportion of dehydrated colloidal microparticles is 60-70 wt%, the proportion of compound microbial agent is 0.5-1.0 wt%, the proportion of improver is 5-10 wt%, and the proportion of garden waste is 20-30 wt%, where garden waste is plant branches and leaves. The fermentation temperature of the mixture in step S3 is 55-65℃, the fermentation time is ≥7 days, and the mixture is turned over once every 48 hours during the fermentation process.

[0026] The passivating agent includes 200-mesh zero-valent iron powder, potassium persulfate, and chitosan, with an addition ratio of 1.5:0.5:0.3 (wt%). In this example, the leaching concentration of heavy metal Pb is 0.08 mg / L, the leaching concentration of Cd is 0.005 mg / L, the formaldehyde residue is 3.2 mg / kg, the organic matter content is 38%, and the humification coefficient is 0.85.

[0027] Mechanism of action: Zero-valent iron reduces heavy metal ions, potassium persulfate oxidizes and decomposes formaldehyde / benzene compounds, and chitosan enhances the heavy metal fixation effect through chelation. Example

[0028] The curing agent added in step S2 includes polyaluminum chloride and quicklime. The amount of polyaluminum chloride is 5 kg / ton of mud, and the amount of quicklime is 3 kg / ton of mud. Other parameters are the same as in Example 1. In this example, the leaching concentration of heavy metal Pb is 0.09 mg / L, the leaching concentration of Cd is 0.006 mg / L, the moisture content after dehydration is 44%, and the organic matter content is 36%. Example

[0029] The curing agent added in step S2 includes polyaluminum chloride and quicklime. The amount of polyaluminum chloride is 8 kg / ton of mud, and the amount of quicklime is 5 kg / ton of mud. Other parameters are the same as in Example 1. In this example, the leaching concentration of heavy metal Pb is 0.07 mg / L, the leaching concentration of Cd is 0.004 mg / L, the moisture content after dehydration is 42%, and the organic matter content is 37%. Example

[0030] The modifiers include bentonite and humic acid in a ratio of 6:4. Other parameters are the same as in Example 1. In this example, the organic matter content is 40%, the humification coefficient is 0.88, and the heavy metal Pb leaching concentration is 0.08 mg / L. Example

[0031] The modifiers include bentonite and humic acid in a ratio of 8:2. Other parameters are the same as in Example 1. In this example, the organic matter content is 35%, the humification coefficient is 0.82, and the heavy metal Pb leaching concentration is 0.07 mg / L. Example

[0032] The passivating agent includes 200-mesh zero-valent iron powder, potassium persulfate, and chitosan, and the addition ratio is 1.0:0.5:0.3 (wt%). Other parameters are the same as in Example 1. In this example, the leaching concentration of heavy metal Pb is 0.10 mg / L, the leaching concentration of Cd is 0.007 mg / L, and the formaldehyde residue is 4.5 mg / kg. Example

[0033] The passivating agent includes 200-mesh zero-valent iron powder, potassium persulfate, and chitosan, with an addition ratio of 2.0:0.5:0.3 (wt%). Other parameters are the same as in Example 1. In this example, the leaching concentration of heavy metal Pb is 0.06 mg / L, the leaching concentration of Cd is 0.003 mg / L, and the formaldehyde residue is 2.8 mg / kg. Note: "-" indicates that this indicator was not detected separately in the examples, and the default is to refer to the basic ratio trend.

[0034] In the above embodiments, by adjusting the ratio of curing agent, modifier, and passivating agent, the moisture content, organic matter content, and pollutant removal effect of the product can be controlled. Among them, Example 1 has the best overall performance, with a heavy metal curing rate of 96.3%, an organic matter content of 38%, and a humification coefficient of 0.85, meeting the standards for agricultural humus soil; Example 7 has the best heavy metal removal effect, with Pb / Cd leaching concentrations reduced to 0.06 mg / L and 0.003 mg / L, respectively, making it suitable for construction mud treatment scenarios with high heavy metal pollution risk.

[0035] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for co-preparing humus from urban construction mud and garden waste, characterized in that, Includes the following steps: S1: Pre-treat the construction mud with a moisture content of 80-90% and a pH value to obtain gravel / cement microparticles and colloidal microparticles. S2: Add a curing agent to the obtained colloidal particles and perform pressure filtration and dehydration; S3: Add compound microbial agent, garden waste and amendment to the dehydrated colloidal microparticles obtained in step S2 and mix them. Adjust the moisture content of the mixture to 45-55% and the C / N ratio to 25-30, and then carry out fermentation. S4: Add a passivating agent to the fermented mixture to fix heavy metals and remove organic pollutants to obtain humus soil. S5: The humus soil is piled up in the dark at 25-30℃ for 15 days and turned over intermittently. After the pile is finished, it is passed through a 4mm sieve to remove undegraded impurities and obtain the final product of humus soil.

2. The method for co-preparing humus from urban construction mud and garden waste according to claim 1, characterized in that: The compound microbial agent contains Bacillus subtilis, Aspergillus niger, and actinomycetes in a ratio of 5:3:

2.

3. The method for co-preparing humus from urban construction mud and garden waste according to claim 2, characterized in that: The modifier includes bentonite and humic acid in a ratio of 7:

3.

4. The method for co-preparing humus from urban construction mud and garden waste according to claim 3, characterized in that: The curing agent added in step S2 includes polyaluminum chloride and quicklime, and the amount of polyaluminum chloride used is 5-8 kg / ton of mud, and the amount of quicklime used is 3-5 kg / ton of mud.

5. The method for co-preparing humus from urban construction mud and garden waste according to claim 4, characterized in that: In step S3, the proportion of dehydrated colloidal microparticles is 60-70 wt%, the proportion of compound microbial agent is 0.5-1.0 wt%, the proportion of conditioner is 5-10 wt%, and the proportion of garden waste is 20-30 wt%, wherein the garden waste is plant branches and leaves.

6. The method for co-preparing humus from urban construction mud and garden waste according to claim 5, characterized in that: The fermentation temperature of the mixture in step S3 is 55-65℃, the fermentation time is ≥7 days, and the mixture is turned over once every 48 hours during the fermentation process.

7. The method for co-preparing humus from urban construction mud and garden waste according to claim 1, characterized in that: The passivating agent includes 200-mesh zero-valent iron powder, potassium persulfate, and chitosan, and the addition ratio is 1-2:0.5:0.3 (wt%).

8. A system for co-preparing humus from urban construction mud and garden waste according to any one of claims 1-7, characterized in that: It includes a multi-stage separation system, a plate and frame filter press, and a fermentation tank. The multi-stage separation system is used for the pretreatment of construction mud in step S1, and the plate and frame filter press is used for dewatering in step S2. The filter pressure is 1.5-2.0 MPa and the filter time is 30 min.

9. The system for co-preparing humus from urban construction mud and garden waste according to claim 8, characterized in that: The multi-stage separation system includes a primary magnetic separator, a secondary eddy current separator, and a tertiary hydrocyclone separator, which respectively employ a magnetic separator, an eddy current separator, and a hydrocyclone.

10. The system for co-preparing humus from urban construction mud and garden waste according to claim 9, characterized in that: The gravel separated by the three-stage hydrocyclone has a particle size >2mm, and the cement microparticles have a particle size of 0.05-2mm.

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