Method for preparing planting soil by coupling dredged sludge and perishable solid waste

Abstract

The invention discloses a method for preparing planting soil by coupling dredged sludge and perishable solid waste, which comprises the following steps of: firstly, respectively pretreating the dredged sludge and the perishable solid waste: filtering out large particles and impurities from the dredged sludge by using a grillage machine, adjusting the solid content of slurry to be more than 30% by using an adjusting tank so as to meet the composting requirement, and adjusting the solid content of the perishable solid waste to be more than 30% by using an adjusting tank so as to meet the composting requirement; the method comprises the following steps: firstly, removing non-degradable impurities by adopting mechanical sorting in combination with manual assistance to ensure the purity of the material, then crushing and adjusting the particle size to be less than 10mm to improve the subsequent fermentation rate and uniformity, and then adding a proper amount of recarburization conditioner for self-fermentation to adjust the C / N ratio and the water content, removing peculiar smell and preliminarily stabilizing the material; mixing the pretreated dredged sludge and perishable solid waste in proportion, and providing oxygen by stages by adopting an intermittent aeration composting process, so that organic matters are degraded, compost is mature, and finally, planting soil suitable for greening is prepared. According to the method, resource utilization of the dredged sludge and perishable solid waste is achieved, and the shortage of greening soil resources can be relieved.

Description

Technical Field

[0001] The invention relates to planting soil preparation, and in particular to a method for preparing planting soil by coupling dredged sludge and perishable solid waste. Background Art

[0002] With the development of urbanization, the demand for planting soil in urban greening is increasing. However, since natural soil resources are limited and over-exploitation may cause ecological damage, the development of sustainable planting soil resources has become an urgent problem to be solved.

[0003] At present, a large amount of dredged sludge and perishable solid waste (such as kitchen waste, fallen leaves, straw and other waste plants) is generated every year, which not only occupies land resources but also poses a threat to the environment. Among them: dredged sludge is rich in organic matter and minerals, but its high water content and possible pollutants limit its direct utilization; perishable solid waste has a high organic matter content, but is easy to decay and deteriorate, which also limits its direct utilization. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing planting soil by coupling dredged sludge and perishable solid waste. This method not only realizes the resource utilization of dredged sludge and perishable solid waste, but also alleviates the shortage of greening soil resources, and is both economical and environmentally friendly.

[0005] The technical solution adopted by the present invention is: A method for preparing planting soil by coupling dredged sludge and perishable solid waste: the dredged sludge and perishable solid waste are pretreated respectively: for the dredged sludge, large particles and debris are first filtered out by a screen machine, and then the solid content of the sludge is adjusted to above 30% in a regulating tank to meet the composting requirements; for the perishable solid waste, non-degradable impurities are first removed by mechanical sorting combined with manual assistance to ensure the purity of the material, and then the material is crushed and adjusted to a particle size of less than 10 mm to improve the subsequent fermentation rate and uniformity, and then a proper amount of carbon-enhancing conditioner is added for self-fermentation to adjust the C / N ratio and water content, remove odor and preliminarily stabilize the material; then the pretreated dredged sludge and perishable solid waste are mixed in proportion, and an intermittent aeration composting process is used to provide oxygen in stages to degrade organic matter and mature the compost, so as to finally obtain planting soil suitable for greening.

[0006] Preferably, the source of the dredged sludge includes dredged sludge from rivers, lakes and reservoirs.

[0007] Preferably, the sources of the perishable solid waste include kitchen waste and discarded plants.

[0008] Preferably, the method of filtering out large particles and debris from the dredged sludge through a screen machine is as follows: two layers of screen mesh are arranged in the screen machine, and a layer of filter mesh with dense cells is arranged between the two layers of screen mesh, the dredged sludge is transported to the screen machine, and the dredged sludge passes through the multi-layer filter structure in turn to quickly filter out large particles and debris. During the filtration process, the conveying gap of the dredged sludge is used to clean up floating objects and impurities in the screen machine to ensure that the sludge is uniform and the flow of the mud-water mixture is maintained undisturbed.

[0009] Preferably, the method for adjusting the mud concentration of the dredged sludge through the regulating tank is: the regulating tank adopts a two-level partition design, the mud and water mixture after filtering the dredged sludge is transported to the regulating tank, and the mud and water separation is gradually completed through step-by-step height difference sedimentation to ensure that the solid content of the mud is above 30%, and the clean water is discharged from the end of the sedimentation tank.

[0010] Preferably, the method for self-fermentation of perishable solid waste is: first, the crushed perishable solid waste and the carbon-enhancing agent are mixed in appropriate proportions, and a water-absorbing material is added to adjust the C / N ratio to 25:1-30:1, and the moisture content is adjusted to 50%-60%, and then self-fermented at a temperature of 40-50°C for 3-5 days to start the microbial degradation process through natural heat accumulation, remove odors and preliminarily stabilize the material. During the self-fermentation process, ventilation is ensured and the pile is turned as needed to ensure uniform ventilation of the material and prevent anaerobic phenomena.

[0011] Preferably, the crushed perishable solid waste and the carbon-enhancing agent are mixed in a mass ratio of 7:3.

[0012] Preferably, the method of using intermittent aeration composting process for dredged sludge and perishable solid waste is to firstly mix the pretreated dredged sludge and perishable solid waste in appropriate proportions and then load them into the reaction device, and adjust the moisture content to or close to 55%, and then adopt forced intermittent ventilation aeration to meet the different oxygen requirements of each stage of composting: Initial stage: The temperature of the pile is gradually raised from ambient temperature to 30-40°C, the aeration pump is operated intermittently, the aeration mode is turned on for 5 minutes and turned off for 10 minutes, and the ventilation rate is set to 3.5 L / (min·kg) to ensure sufficient oxygen supply to activate microbial activity; Heating and high temperature stage: The temperature of the pile gradually rises to a high temperature of 40-60°C, and the aeration pump runs intermittently. The aeration mode is turned on for 5 minutes and off for 5 minutes to maintain the amount of oxygen required by the microorganisms and discharge excess heat. When the temperature approaches 50°C, the ventilation volume is appropriately reduced to avoid excessive heat loss and provide an ideal high temperature environment for thermophilic bacteria. Cooling stage: The pile gradually cools down and the temperature is slightly higher than the ambient temperature. The aeration pump runs intermittently, and the aeration mode is turned on for 5 minutes and off for 20 minutes to ensure the ventilation needs of the pile. Mature stage: The temperature of the pile is close to the ambient temperature and the compost reaches maturity.

[0013] Preferably, the compost is not turned during the temperature rise and high temperature stage to ensure oxygen supply to the compost and reduce heat loss. The compost is turned once a week during the temperature drop stage and twice a week during the mature stage to ensure uniformity and stability of the compost.

[0014] Preferably, the pretreated dredged sludge and perishable solid waste are mixed in a mass ratio of 7:3.

[0015] The beneficial effects of the present invention are: The method couples dredged sludge with perishable solid waste to obtain planting soil, which not only realizes the resource utilization of dredged sludge and perishable solid waste, but also alleviates the shortage of greening soil resources, and is both economical and environmentally friendly. According to the properties of dredged sludge and perishable solid waste, the method first performs various pretreatments and then conducts mixed composting, which can not only effectively physically screen, biodegrade and passivate heavy metals and organic pollutants in the raw materials, reduce environmental risks, but also simplify the process flow and reduce processing costs. The planting soil prepared by the method has uniform texture and good fertilizer efficiency, which can ensure plant growth. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a process flow chart for preparing planting soil by coupling dredged sludge and perishable solid waste. DETAILED DESCRIPTION

[0017] The present application is further described below in conjunction with the accompanying drawings and embodiments.

[0018] This embodiment discloses a method for preparing planting soil by coupling dredged sludge and perishable solid waste, such as Figure 1 As shown, the steps include: S1. Pre-treat dredged sludge and perishable solid waste separately: For dredged sludge, it is first filtered through a screen machine to remove large particles and debris, and then passed through a regulating tank to adjust the solid content of the sludge to above 30% to meet the composting requirements; For perishable solid waste, mechanical sorting combined with manual assistance is first used to remove non-degradable impurities (such as metals, plastics, glass, etc.) to ensure the purity of the material, and then crushed to a particle size of less than 10 mm to improve the subsequent fermentation rate and uniformity, and then an appropriate amount of carbon-enhancing agent is added for self-fermentation to adjust the C / N ratio and moisture content, remove odor, and initially stabilize the material; S2. Mix the pre-treated dredged sludge and perishable solid waste in proportion, and use intermittent aeration composting process to provide oxygen in stages to degrade organic matter and mature the compost, and finally produce planting soil suitable for greening.

[0019] In this embodiment, the source of the dredged sludge includes dredged sludge obtained from dredging rivers, lakes, reservoirs and other water bodies, and the source of perishable solid waste includes kitchen waste, discarded plants and other perishable solid waste continuously generated by urban life. The sources of the two are stable and large in quantity.

[0020] In this embodiment, the method of filtering out large particles and debris from dredged sludge through a screen machine is: Two layers of grid nets are set in the grid machine, and a layer of densely packed cell filter net (e.g., size of 50mm×50mm) is set between the two layers of grid nets to transport the dredged sludge to the grid machine. The dredged sludge passes through the multi-layer filtering structure in turn to quickly filter out large particles and debris. During the filtration process, the conveying gap of the dredged sludge is used to clean up the floating objects and impurities in the grid machine to ensure that the sludge is uniform and maintain the flow of the mud-water mixture without interference.

[0021] In this embodiment, the method for adjusting the concentration of dredged sludge in the regulating tank is: The regulating pond adopts a two-level zoning design. The mud and water mixture after dredging sludge filtering is transported to the regulating pond. The mud and water separation is gradually completed through step-by-step height difference sedimentation to ensure that the solid content of the mud is above 30%, and the clean water is discharged from the end of the sedimentation tank.

[0022] In this embodiment, the method for self-fermentation of perishable solid waste is: First, mix the crushed perishable solid waste and the carbon-enhancing agent in a mass ratio of 7:3, and add absorbent materials (such as sawdust) to adjust the C / N ratio to 25:1-30:1 and the moisture content to 50%-60%. Then, self-ferment at 40-50°C for 3-5 days to start the microbial degradation process through natural heat accumulation, remove odors and initially stabilize the materials. During the self-fermentation process, ensure ventilation and turn the pile as needed to ensure uniform ventilation of the materials and prevent anaerobic phenomena.

[0023] In this embodiment, the method of using intermittent aeration composting process for dredged sludge and perishable solid waste is: First, the pre-treated dredged sludge and perishable solid waste are fully mixed in a mass ratio of 7:3 and then loaded into the reaction device (placed in medium-sized insulated compost barrels at various locations), and the moisture content is adjusted to or close to 55%. Then, forced intermittent ventilation is used to meet the different oxygen requirements of each stage of composting: Initial stage (1st to 3rd day): The temperature of the pile is gradually raised from ambient temperature to 30-40℃, the aeration pump is operated intermittently, the aeration mode is turned on for 5 minutes and turned off for 10 minutes, and the ventilation rate is set to 3.5 L / (min·kg) to ensure sufficient oxygen supply to activate microbial activity; Heating and high temperature stage (3rd to 8th day): The temperature of the pile gradually rises to a high temperature of 40-60℃, and the aeration pump runs intermittently. The aeration mode is on for 5 minutes and off for 5 minutes to maintain the amount of oxygen required by the microorganisms and discharge excess heat. When the temperature approaches 50℃, the ventilation volume is appropriately reduced to avoid excessive heat loss and provide an ideal high temperature environment for thermophiles. Cooling stage (9th to 28th day): The pile gradually cools down and the temperature is slightly higher than the ambient temperature. The aeration pump runs intermittently, and the aeration mode is turned on for 5 minutes and off for 20 minutes to ensure the ventilation needs of the pile. Mature stage: The temperature of the pile is close to the ambient temperature and the compost reaches maturity.

[0024] During this period, the compost will not be turned during the warming and high temperature stages to ensure oxygen supply to the compost and reduce heat loss. The compost will be turned once a week during the cooling stage and twice a week during the mature stage to ensure uniformity and stability of the compost.

[0025] The fermentation cycle is about 50 days in total, and the pile and ambient temperature data are recorded at 16:00 every afternoon.

[0026] This method couples dredged sludge with perishable solid waste to obtain planting soil, which not only realizes the resource utilization of dredged sludge and perishable solid waste, but also alleviates the shortage of greening soil resources, and is both economical and environmentally friendly; this method, based on the properties of dredged sludge and perishable solid waste, first performs various pretreatments and then conducts mixed composting, which can not only effectively physically screen, biodegrade and passivate heavy metals and organic pollutants in the raw materials, reduce environmental risks, but also simplify the process flow and reduce processing costs; after trial application, the planting soil prepared by this method has uniform texture and good fertilizer efficiency, which can ensure plant growth.

[0027] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

Claims

1. A method for preparing planting soil by coupling dredged sludge and perishable solid waste, characterized in that: First, the dredged sludge and perishable solid waste are pretreated separately: for the dredged sludge, large particles and debris are first filtered out by a screen machine, and then the solid content of the sludge is adjusted to above 30% in the regulating tank to meet the composting requirements. For the perishable solid waste, mechanical sorting combined with manual assistance is used to remove non-degradable impurities to ensure the purity of the material, and then the material is crushed and adjusted to a particle size of less than 10 mm to improve the subsequent fermentation rate and uniformity, and then an appropriate amount of carbon-enhancing agent is added for self-fermentation to adjust the C / N ratio and moisture content, remove odor and preliminarily stabilize the material; then the pretreated dredged sludge and perishable solid waste are mixed in proportion, and intermittent aeration composting process is used to provide oxygen in stages to degrade organic matter and mature the compost, so as to finally produce planting soil suitable for greening.

2. The method for preparing planting soil by coupling dredged sludge and perishable solid waste as claimed in claim 1, characterized in that: The sources of the dredged sludge include dredged sludge from rivers, lakes and reservoirs.

3. The method for preparing planting soil by coupling dredged sludge and perishable solid waste as claimed in claim 1, characterized in that: The sources of the perishable solid waste include kitchen waste and discarded plants.

4. The method for preparing planting soil by coupling dredged sludge and perishable solid waste as claimed in claim 1, characterized in that: The method of filtering out large particles and debris from dredged sludge through a screen machine is: two layers of screen mesh are set in the screen machine, and a layer of filter mesh with dense cells is set between the two layers of screen mesh, and the dredged sludge is transported to the screen machine. The dredged sludge passes through the multi-layer filter structure in turn to quickly filter out large particles and debris. During the filtration process, the conveying gap of the dredged sludge is used to clean up floating objects and impurities in the screen machine to ensure that the sludge is uniform and the flow of the mud-water mixture is maintained without interference.

5. The method for preparing planting soil by coupling dredged sludge and perishable solid waste as claimed in claim 1, characterized in that: The method of adjusting the concentration of dredged sludge in the regulating tank is: the regulating tank adopts a two-level zoning design, and the mud-water mixture after filtering the dredged sludge is transported to the regulating tank, and the mud and water separation is gradually completed through step-by-step height difference sedimentation to ensure that the solid content of the mud is above 30%, and the clean water is discharged from the end of the sedimentation tank.

6. The method for preparing planting soil by coupling dredged sludge and perishable solid waste as claimed in claim 1, characterized in that: The method for self-fermentation of perishable solid waste is: first mix the crushed perishable solid waste and the carbon-enhancing agent in an appropriate proportion, add absorbent materials to adjust the C / N ratio to 25:1-30:1, adjust the moisture content to 50%-60%, and then self-ferment at a temperature of 40-50°C for 3-5 days to start the microbial degradation process through natural heat accumulation, remove odors and preliminarily stabilize the materials. During the self-fermentation process, ventilation is ensured and the pile is turned as needed to ensure uniform ventilation of the materials and prevent anaerobic phenomena.

7. The method for preparing planting soil by coupling dredged sludge and perishable solid waste as claimed in claim 6, characterized in that: The crushed perishable solid waste and the carbon-enhancing agent are mixed in a mass ratio of 7:

3.

8. The method for preparing planting soil by coupling dredged sludge and perishable solid waste as claimed in claim 1, characterized in that: The method of intermittent aeration composting of dredged sludge and easily degradable solid waste is to first mix the pretreated dredged sludge and easily degradable solid waste in appropriate proportions and then load them into the reaction device, and adjust the moisture content to or close to 55%, and then adopt forced intermittent ventilation aeration to meet the different oxygen requirements of each stage of composting: Initial stage: The temperature of the pile is gradually raised from ambient temperature to 30-40°C, the aeration pump is operated intermittently, the aeration mode is turned on for 5 minutes and turned off for 10 minutes, and the ventilation rate is set to 3.5 L / (min·kg) to ensure sufficient oxygen supply to activate microbial activity; Heating and high temperature stage: The temperature of the pile gradually rises to a high temperature of 40-60°C, and the aeration pump runs intermittently. The aeration mode is turned on for 5 minutes and off for 5 minutes to maintain the amount of oxygen required by the microorganisms and discharge excess heat. When the temperature approaches 50°C, the ventilation volume is appropriately reduced to avoid excessive heat loss and provide an ideal high temperature environment for thermophilic bacteria. Cooling stage: The pile gradually cools down and the temperature is slightly higher than the ambient temperature. The aeration pump runs intermittently, and the aeration mode is turned on for 5 minutes and off for 20 minutes to ensure the ventilation needs of the pile. Mature stage: The temperature of the pile is close to the ambient temperature and the compost reaches maturity.

9. The method for preparing planting soil by coupling dredged sludge and perishable solid waste as claimed in claim 8, characterized in that: No compost turning is done during the warming and high temperature stages to ensure oxygen supply to the compost and reduce heat loss. The compost is turned once a week during the cooling stage and twice a week during the mature stage to ensure uniformity and stability of the compost.

10. The method for preparing planting soil by coupling dredged sludge and perishable solid waste as claimed in claim 8, characterized in that: The pretreated dredged sludge and perishable solid waste are mixed in a mass ratio of 7:3.

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