CN108273821A - It is a kind of using municipal dewatered sludge as the refuse landfill evapotranspiration cover layer of base - Google Patents

Abstract

The invention relates to a waste landfill covering layer based on municipal dewatered sludge, comprising: a base cushion layer, an adjustment layer, a water storage layer and a vegetation layer, and the base cushion layer is mechanically crushed in situ through construction waste and It is obtained by leveling; the adjustment layer is obtained by adding modifying agent I to the dewatered municipal dewatered sludge, stirring evenly, extruding into spherical particles, and placing the spherical particles in a cool and ventilated environment for natural curing and drying; the water storage layer is obtained by municipal The dewatered sludge is obtained by adding modifier II and synthetic fibers and stirring evenly; the vegetation layer is formed by sowing evergreen herb seeds on the surface of the water storage layer and planting shrubs or shrub woody plants. The waste landfill covering layer based on municipal dewatered sludge realizes the optimization of the material and structure of the covering layer, the resource utilization of sludge, and achieves both economic and environmental benefits.

Description

A Landfill Evaporation Overburden Based on Municipal Dewatered Sludge

technical field

The invention relates to the technical field of environmental geotechnical engineering, in particular to a waste landfill covering layer based on municipal dewatered sludge.

Background technique

In order to ensure landfill sanitation and reduce environmental hazards, landfills need to be closed and covered after the landfill is completed. Generally, the composite closure covering structure includes four layers, which are in order from bottom to top: air-conducting layer, anti-seepage layer, drainage layer, and vegetation nutrient soil layer. Although this kind of covering structure has a good anti-seepage effect, the structure is relatively complex, the construction is inconvenient, and the performance requirements of the covering materials are high. Not all landfill sites can easily meet the material requirements, and the cost is huge. In addition, the interlayer interfaces of multilayer structures are mostly weak surfaces, which are prone to cover layer slippage and cause serious engineering disasters.

As an alternative covering structure, Tengfa cover generally consists of two parts, the water storage soil layer and the regulating soil layer, and uses the water storage-release principle to achieve a good anti-seepage effect. During the rainfall period, the water entering the overburden layer is stored through the capillary retardation of the water storage layer to reduce the amount of rainfall infiltration. During the non-rainfall period, the stored water is released through plant transpiration and soil evaporation to restore the water storage capacity of the overburden layer. , this kind of covering system is simple in structure, convenient in construction, low in construction cost, and has good durability. However, the water storage capacity of the water storage soil layer is limited by the water inflow value of the soil. When the matric suction at the interface between the water storage layer and the adjustment layer reaches the water inflow value, the water will soon infiltrate into the landfill. This phenomenon leads to Generally, Tengfa covering layer can only be used in arid and semi-arid areas.

Contents of the invention

The invention provides a waste landfill covering layer based on municipal dewatered sludge, which solves or partially solves the engineering problems of cumbersome construction and inconvenient materials for the composite covering layer in the prior art and general waste covering layer The technical problem of engineering limitations, which can only be used in arid and semi-arid areas, has realized the optimization of the material and structure of the overburden layer, the resource utilization of sludge, and achieved the technical effect of double harvest of economic and environmental benefits.

A kind of municipal dewatered sludge provided by the invention is based on landfill landfill overlay, comprising: base cushion, regulating layer, water storage layer and vegetation layer, wherein:

The base cushion is obtained by in-situ mechanical crushing and leveling of construction waste;

After the municipal dewatered sludge after the dehydration is added with the modified agent I, the adjustment layer is extruded into spherical particles after being stirred evenly, and the spherical particles are placed in a cool and ventilated environment for natural maintenance and drying to obtain;

The water storage layer is obtained by adding modifier II and synthetic fibers to the municipal dewatered sludge, and stirring uniformly;

The vegetation layer is formed by sowing evergreen herbaceous plant seeds on the surface of the water storage layer and planting evergreen trees or shrub woody plants.

As preferably, the maximum block particle size of the crushed construction waste is less than 8cm;

The thickness of the foundation cushion is 10-20cm;

The construction waste includes bricks and concrete blocks.

As preferably, the added mass ratio of the municipal dewatered sludge in the regulating layer to the modifying agent I is 10%-20%;

The spherical particles are unequal-diameter spherical particles with a particle diameter ranging from 0.75 to 2 mm;

The composition and mass ratio of the modifying agent I are: cement 65%-72%, fly ash 25%-30%, CaSO ₄ 3%-6%;

The cement is pozzolan Portland cement or slag Portland cement.

Preferably, the permeability coefficient of the adjustment layer is 1×10 ^-3 to 5×10 ^-3 m/s, and the thickness is

20-30cm.

As a preference, the mass ratio of the municipal dewatered sludge in the water storage layer to the modifier II is 5-8%;

The mass ratio of the municipal dewatered sludge to the synthetic fiber in the water storage layer is 5-8%.

Preferably, the composition and mass ratio of the modifying agent II are: deodorant 5%-10%, cement 50%-60%, carbide slag 35%-40%;

The cement is ordinary Portland cement.

As preferably, described synthetic fiber comprises: polypropylene, polyethylene, glass fiber and nylon fiber;

The length of the synthetic fiber is 2-6 cm.

Preferably, the permeability coefficient of the water storage layer is 3×10 ^-6 to 7×10 ^-6 m/s, and the thickness is

1.0～1.2m.

As a preference, a gutter is provided at the interface between the regulating layer and the water storage layer;

The gutters are prefabricated concrete pipes with a distance of 8-10m and filled with crushed stones.

As a preference, the municipal dewatered sludge has a water content of 75%-85%, and has been screened for impurity removal and heavy metals.

One or more technical solutions provided in this application have at least the following technical effects or advantages:

Due to the use of landfill evacuation covering layer composed of foundation cushion, regulating layer, water storage layer and vegetation layer, the water storage-release principle is used to achieve good anti-seepage effect, and the water storage layer passes through capillary resistance during rainfall Hysteresis will store infiltrating rainwater, and release the stored water through the transpiration of the vegetation layer and soil evaporation during non-rainfall periods, thereby reducing the infiltration of rainwater into the landfill. The synthetic fibers added to the water storage layer are not easy to degrade. On the one hand, it can ensure that the water storage layer does not crack under the action of dry and wet cycles, and at the same time enhance its tensile properties to prevent uneven settlement of the landfill. On the other hand, it can increase the pollution Pores inside the mud to improve water holding capacity. Adding the modifying agent I in the regulating layer can make the sludge particles produce cementation, produce a certain strength and also improve the durability of the sludge particles. Laying the base cushion made of construction waste can, on the one hand, be used as an exhaust layer to evacuate the covering layer, and on the other hand, can effectively realize the resource utilization of a large amount of construction waste. In this way, the engineering problems of cumbersome construction and inconvenient materials for the composite covering layer in the prior art are effectively solved, and the technical problem of the engineering limitation that the general Tengfa covering layer can only be used in arid and semi-arid areas is solved, and the Tengfa covering layer material and The optimization of the structure and the resource utilization of the sludge achieve the technical effect of double harvest of economic and environmental benefits.

Description of drawings

Fig. 1 is the structural representation of the overburden of waste landfill based on municipal dewatered sludge provided by the invention.

(The parts represented by each label in the accompanying drawings are: 1 vegetation layer, 2 water collection ditch, 3 water storage layer, 4 adjustment layer, 5 foundation cushion layer)

Detailed ways

The municipal dewatered sludge-based evacuation overlay provided in the embodiment of the present application solves or partially solves the engineering problems of cumbersome construction and inconvenient materials for the composite overlay in the prior art and the general evacuation overlay. Due to the technical problems of engineering limitations that can only be used in arid and semi-arid areas, the landfill covering layer composed of foundation cushion, regulating layer, water storage layer and vegetation layer has been used to realize the development of covering layer materials. Preparation and structure optimization, resource utilization of sludge, to achieve the technical effect of double harvest of economic and environmental benefits.

Referring to accompanying drawing 1, a kind of municipal dewatered sludge is provided by the present invention as the base landfill evacuation covering layer design, comprises preparation and structure optimization of evaporating covering layer material, evaporating covering layer structure comprises from bottom to top : foundation cushion layer 5, adjustment layer 4, water storage layer 3 and vegetation layer 1.

Basic cushion layer 5: first stack the construction waste on top of the waste dump, and then carry out in-situ mechanical crushing to ensure that the maximum particle size of the crushed block is less than 8cm, and then level it, and the final thickness is 10-20cm; preferably Construction waste includes bricks, concrete blocks, etc.

Adjustment layer 4: Add modifier I with a mass ratio of 10%-20% to the municipal dewatered sludge, stir evenly, and use a sludge granulator to extrude into spherical particles with a particle size range of 0.75-2mm. The spherical particles are naturally cured and dried in a cool and ventilated environment, and can be put into use after 7 days of curing; the composition and mass ratio of the modified agent I are: cement 65%-72%, fly ash 25%-30%, CaSO43 %-6%, preferably the cement is pozzolan Portland cement or slag Portland cement; the permeability coefficient of the adjustment layer 4 is 1×10 ^-3 ~5×10 ^-3 m/s, and the thickness is 20 -30cm.

Water storage layer 3: Add the modification agent II with a mass ratio of 5%-8% and the synthetic fiber with a mass ratio of 3%-5% to the municipal dewatered sludge, and stir evenly; the composition of the modified agent II and The mass ratio is: 5%-10% of deodorant, 50%-60% of cement, 35%-40% of carbide slag, and the cement is ordinary Portland cement. Preferably, the synthetic fibers include polypropylene, polyethylene, glass fibers and nylon fibers, etc., with a length of 2 to 6 cm; the permeability coefficient of the water storage layer 3 is 3×10 ^-6 to 7×10 ^-6 m/s , the thickness is 1.0-1.2m.

Vegetation layer 1: Sow evergreen herbaceous plant seeds on the upper surface of the water storage layer 3 at a ratio of 25-28g/m ² , and plant trees or shrubs with a spacing of 1.5-2m.

Further, a gutter 2 is set at the interface between the adjustment layer 4 and the water storage layer 3, preferably the gutter 2 is a prefabricated concrete pipe with a spacing of 8-10m, and the inside is filled with gravel. At the interface between the adjustment layer 4 and the water storage layer 3, the gutter 2 is set every 8-10m, which can enhance the lateral drainage capacity of the adjustment layer, and effectively reduce the infiltration of rainwater when the heavy rainfall acts for a long time, thereby ensuring the drainage. Hair cover can be applied in wet areas.

Further, the municipal dewatered sludge has a water content of 75%-85%, and has been screened for impurities and heavy metals.

The structure of the landfill evacuation cover layer provided by the application is described in detail below by three specific embodiments:

Example 1

Municipal dewatered sludge with a moisture content of 80% is selected, and it is prepared for use after being screened for impurities and heavy metals.

1. Preparation of foundation cushion layer 5

The construction waste is piled on the top of the waste pile first, and mechanically crushed in situ. After crushing, the largest particle size of the block is less than 5cm, and then leveled, and the final thickness is 12cm.

2. Preparation of adjustment layer 4

Take 1000kg of municipal dewatered sludge, add 120kg of modified agent I, mix well, and use a sludge granulator to extrude into spherical particles with a particle size range of 0.75-2mm, and place the spherical particles in a cool and ventilated environment for natural maintenance Drying, curing for 7 days, the permeability coefficient of the test sludge heap is

2.3×10 ^-3 m/s, then stack the materials on the foundation cushion layer 5, lightly compact and level them, and finally lay prefabricated concrete water collection pipes on the surface at intervals of 8m, and fill the pipes with gravel. The final conditioning layer 4 has a thickness of 23 cm.

The composition and mass ratio of modifying agent I are: pozzolan Portland cement 68%, fly ash 28%, CaSO 44%.

3. Preparation of water storage layer 3

Take 5000kg of municipal dewatered sludge, add 250kg of modified agent II, and add nylon fibers with a mass ratio of 150kg and a length of 2 to 4cm. After stirring evenly, the permeability coefficient of the modified sludge is tested to be

4.3×10 ^-6 m/s, and then directly stacked on the adjustment layer 4 and leveled, the stacking thickness is 1.1m. The composition and mass ratio of the modifier II are: deodorant 6%, cement 54%, and carbide slag 40%.

4. Preparation of vegetation layer 1

After the completion of the construction, the upper surface of the water storage layer 3 was sowed with mixed seeds of bermudagrass and ryegrass at a ratio of 25g/m ² , and planted Euonymus euonymus with a plant spacing of 1.8m. After planting, cover the straw mat on the surface of the water storage layer 3, and regularly sprinkle water for maintenance.

The covering layer obtained in this embodiment has good anti-seepage performance and is suitable for rainy and humid areas.

Example 2

Municipal dewatered sludge with a moisture content of 83% is selected, and is ready for use after screening for impurities and heavy metals.

1. Preparation of foundation cushion layer 5

The construction waste is piled on top of the waste pile first, and mechanically crushed in situ. After crushing, the largest particle size of the block is less than 6cm, and then leveled, and the final thickness is 15cm.

2. Preparation of adjustment layer 4

Take 1000kg of municipal dewatered sludge, add 150kg of modified agent I, mix well, and use a sludge granulator to extrude into spherical particles with a particle size range of 0.75-2mm, and place the spherical particles in a cool and ventilated environment for natural maintenance Drying, curing for 8 days, the permeability coefficient of the test sludge heap is

3.5×10 ^-3 m/s, then stack the materials on the foundation cushion layer 5, lightly compact and level them, and finally lay prefabricated concrete water collection pipes on the surface at intervals of 8m, and fill the pipes with gravel, The final conditioning layer 4 has a thickness of 25 cm.

The composition and mass ratio of modifying agent I are: pozzolan Portland cement 69%, fly ash 26%, CaSO 45%.

3. Preparation of water storage layer 3

Take 5000kg of municipal dewatered sludge, add 280kg of modified agent II, and add nylon fibers with a mass ratio of 250kg and a length of 2 to 6cm. After stirring evenly, the permeability coefficient of the modified sludge is tested to be

5.7×10 ^-6 m/s, and then directly stacked on the adjustment layer 4 and leveled, the stacking thickness is 1.2m. The composition and mass ratio of the modifier II are: deodorant 5%, cement 57%, and carbide slag 38%.

4. Preparation of vegetation layer 1

After the completion of the construction, the upper surface of the water storage layer 3 was sowed with mixed seeds of Bermudagrass and Ophiopogon japonicus at a ratio of 26g/m ² , and planted Euonymus euonymus with a plant spacing of 1.8m. After planting, cover the straw mat on the surface of the water storage layer 3, and regularly sprinkle water for maintenance.

The covering layer obtained in this embodiment has good anti-seepage performance and is suitable for rainy and humid areas.

Example 3

Municipal dewatered sludge with a moisture content of 85% is selected, and is ready for use after screening for impurities and heavy metals.

1. Preparation of foundation cushion layer 5

The construction waste is piled on the top of the waste pile first, and mechanically crushed in situ. After crushing, the largest particle size of the block is less than 6cm, and then leveled, and the final thickness is 18cm.

2. Preparation of adjustment layer 4

Take 1000kg of municipal dewatered sludge, add 180kg of modified agent I, stir evenly, and use a sludge granulator to extrude into spherical particles with a particle size range of 0.75-2mm, and place the spherical particles in a cool and ventilated environment for natural maintenance Drying, curing for 10 days, the permeability coefficient of the test sludge heap is

1.7×10 ^-3 m/s, and then stack the materials on the foundation cushion 5, lightly compact and level them, and finally lay prefabricated concrete water collection pipes at intervals of 8m on the surface, and fill the pipes with gravel. The final conditioning layer 4 has a thickness of 25 cm. The composition and mass ratio of the modifying agent I are: pozzolan Portland cement 67%, fly ash 27%, CaSO ₄ 6%.

3. Preparation of water storage layer 3

Take 5000kg of municipal dewatered sludge, add 300kg of modified agent II, and add nylon fibers with a mass ratio of 250kg and a length of 2 to 5cm. After stirring evenly, the permeability coefficient of the modified sludge is tested to be

6.8×10 ^-6 m/s, and then directly stacked on the adjustment layer 4 and leveled, the stacking thickness is 1.2m. The composition and mass ratio of the modifier II are: deodorant 5%, cement 60%, and carbide slag 35%.

4. Preparation of vegetation layer 1

After the completion of the construction, the upper surface of the water storage layer 3 was sown with mixed seeds of bermudagrass and ryegrass at a ratio of 28g/m ² , and anise thorns were planted at a distance of 2.0m. After planting, cover the straw mat on the surface of the water storage layer 3, and regularly sprinkle water for maintenance.

The covering layer obtained in this embodiment has good anti-seepage performance and is suitable for rainy and humid areas.

It can be seen from the above examples that the design of the waste landfill cover layer based on municipal dewatered sludge provided by the application includes the preparation and structure optimization of the cover layer material, and utilizes the principle of water storage-release to achieve good Anti-seepage effect. Since the permeability coefficient of the regulating layer is much larger than that of the water storage layer, the water storage layer will store infiltrating rainwater through capillary blockage during the rainfall period, and release the stored water through the transpiration of the vegetation layer and the evaporation of the soil during the non-rainfall period. Reduce rainwater infiltration into the landfill. As the rainfall intensifies, the infiltration of rainwater increases, and the rainwater will generate lateral drainage at the interface between the adjustment layer and the water storage layer, but there is usually a lateral drainage distance of 8-10m. After the drainage length is greater than this distance, the rainwater will further Seep down into the regulating layer, and the covering layer will fail. Therefore, the present invention sets a water collecting ditch at the interface between the water storage layer and the regulating layer for centralized drainage, so as to ensure that the covering layer can be applied in humid areas. In order to achieve a better capillary retardation effect, it is necessary to ensure that the permeability coefficient of the adjustment layer is 1×10 ^-3 to 5×10 ^-3 m/s, and the permeability coefficient of the water storage layer is 3×10 ^-6 to 7×10 ^-6 m/s . In order to enhance the transpiration of the vegetation layer, choose evergreen herb mixed with shrubs or shrubs. The water storage layer based on sludge is rich in nutrients, which can be used for the good growth of the vegetation layer. The synthetic fibers added to the water storage layer are not easy to degrade. On the one hand, it can ensure that the water storage layer does not crack under the action of dry-wet cycles, and at the same time enhance its tensile properties to prevent uneven settlement of the landfill. On the other hand, it can increase the pollution Pores inside the mud to improve water holding capacity. Adding the modifying agent I in the adjustment layer can cause the sludge particles to have a cementation effect, produce a certain strength, and can also improve the durability of the sludge particles. Laying the base cushion made of construction waste can, on the one hand, be used as an exhaust layer for the evacuation covering layer, and on the other hand, can effectively realize the resource utilization of a large amount of construction waste.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. a kind of using municipal dewatered sludge as the refuse landfill evapotranspiration cover layer of base, which is characterized in that including：Blinding layer, Regulating course, reservoir bed and vegetable layer, wherein：

The blinding layer carries out Mechanical Crushing in situ by building waste and flattens acquisition；

After the regulating course adds improved chemical I by dewatered municipal dewatered sludge, rear ball up is stirred evenly Grain, and the spherical particle is placed in natural curing drying under shady and cool ventilation environment and is obtained；

After the reservoir bed adds improved chemical II and synthetic fibers by the municipal dewatered sludge, acquisition is stirred evenly；

The vegetable layer plants aiphyllium or shrub wood by sowing evergreen herbage's seed in the water storage layer surface This plant and formed.

2. as described in claim 1 using municipal dewatered sludge as the refuse landfill evapotranspiration cover layer of base, which is characterized in that

The maximum block grain size of the broken building waste is less than 8cm；

The thickness of the blinding layer is 10-20cm；

The building waste includes brick, concret block.

3. as described in claim 1 using municipal dewatered sludge as the refuse landfill evapotranspiration cover layer of base, which is characterized in that

The addition mass ratio of the municipal dewatered sludge and the improved chemical I in the regulating course is 10%-20%；

The spherical particle is the not isometrical spherical particle that particle size range is 0.75-2mm；

The constituent and mass ratio of the improved chemical I be：Cement 65%-72%, flyash 25%-30%, CaSO₄3%-6%；

The cement is portland-pozzolan cement or portland slag cement.

4. as described in claim 1 using municipal dewatered sludge as the refuse landfill evapotranspiration cover layer of base, which is characterized in that

The infiltration coefficient of the regulating course is 1 × 10^-3~5 × 10^-3M/s, thickness are 20~30cm.

5. as described in claim 1 using municipal dewatered sludge as the refuse landfill evapotranspiration cover layer of base, which is characterized in that

The mass ratio of the municipal dewatered sludge and the improved chemical II in the reservoir bed is 5~8%；

The mass ratio of the municipal dewatered sludge and the synthetic fibers in the reservoir bed is 5~8%.

6. as claimed in claim 5 using municipal dewatered sludge as the refuse landfill evapotranspiration cover layer of base, which is characterized in that

The constituent and mass ratio of the improved chemical II be：Deodorant 5%-10%, cement 50%-60%, carbide slag 35%-40%；

The cement is Portland cement.

7. as claimed in claim 5 using municipal dewatered sludge as the refuse landfill evapotranspiration cover layer of base, which is characterized in that

The synthetic fibers include：Polypropylene, polyethylene, glass fibre and nylon fiber；

The length of the synthetic fibers is 2~6cm.

8. as described in claim 1 using municipal dewatered sludge as the refuse landfill evapotranspiration cover layer of base, which is characterized in that

The infiltration coefficient of the reservoir bed is 3 × 10^-6~7 × 10^-6M/s, thickness are 1.0~1.2m.

9. as described in claim 1 using municipal dewatered sludge as the refuse landfill evapotranspiration cover layer of base, which is characterized in that

Collecting gutter is set at the regulating course and the interface of the reservoir bed；

The collecting gutter is precast concrete pipeline, spacing 8-10m, and internal filling rubble.

10. as described in claim 1 using municipal dewatered sludge as the refuse landfill evapotranspiration cover layer of base, which is characterized in that

The moisture content of the municipal administration dewatered sludge is 75%-85%, and is screened out by removal of impurities screening and heavy metal.