Selection skills of HDPE geomembrane for tailings and solid waste treatment
Selection skills of HDPE geomembrane for tailings and solid waste treatment
Landfill technology is one of the main methods for the treatment of solid hazardous waste and the tailings and slag fields. It is a municipal solid waste treatment technology developed from the traditional waste stacking and landfill technology. The key to burying technology, the most common and reliable way and technology in anti-seepage engineering is to set up and lay HDPE geomembrane.
Landfill leakage and pollution to the environment are very harmful. After the soil is polluted, it will be salinized and poisoned, and pathogens such as parasites and pathogenic bacteria in the soil can make people sick. Infiltration can also contaminate groundwater and eventually enter the human food chain, causing serious harm to humans. Since the 1980s abroad, HDPE high-density polyethylene geomembrane with a thickness of 1-2 mm has been used in the anti-seepage treatment of landfills. Geomembrane landfill liner has become a mature technology and has been used more and more.
Solid waste landfill generally uses mountain cols, excavated mines, etc. to landfill and prevent seepage. The landfill covers geomembrane is to be filled with thousands of tons of garbage, so cover landfill geomembrane with a thickness of more than 1.5mm is generally used, and the width should not be less than 6 meters to reduce welding seams. Because practice has proved that 70% of the leakage of the landfill occurs in the welding seam. Rough surface geomembrane for landfill can be used on the slope surface to increase the friction coefficient and maximize the available volume.
The construction sequence is: site cleaning, construction of drainage culverts at the bottom of the site, leveling of the bottom and slopes of the site, laying of groundwater drainage system, laying of hdpe landfill geomembrane and setting of leachate collection system, building of zoning dams and construction of temporary access roads, waste admission Laying of landfill and closure covering systems.
1. Rolling, cleaning and leveling the surface to be laid, digging blind trenches, and laying out exhaust and drainage pipes. More specific basic treatment can be dealt with according to design requirements.
2. After laying the geotechnical protection liner, the hdpe landfill geomembrane can be laid. Prepare heavy objects such as sandbags, and compress the laid HDPE landfill geomembrane to prevent the wind from blowing. When laying, the welding seam should be minimized, and the most suitable laying scheme should be selected according to the actual site size.
3. Before welding, test welding is performed first, and appropriate welding parameters are selected according to the climate of the day. When welding, professional welding equipment should be used. For large-area welding, use a double-track hot-melt automatic crawling welding machine; for T-shaped and cross-shaped welding and scar repair, a hot-melt extrusion welding machine should be used.
4. Welding on steep slopes can be done with the help of rope ladders or scaffolding. Welder technicians need to take safety measures.
5. Anchoring trench excavation: U-shaped trench with a size of 50cm×50cm×50cm, backfill or use plain concrete for anchoring; for steep slopes, platforms can be dug and then anchor trenches can be dug for anchoring; anchoring nails and battens can be used for rock layers Make an anchor seal.
There are several considerations when selecting HDPE geomembranes for a hazardous waste landfill project:
Steep slope angle (interfacial friction); low water permeability; high tear and puncture resistance (this performance requirement depends on the actual geography of the project); chemical resistance; ; UV resistance; hydrostatic pressure resistance; tensile ductility;
Types of HDPE landfill geomembrane for tailings, slag yard and geomembrane for solid waste treatment
1. Single-layer anti-seepage structure:
The single-layer anti-seepage structure from top to bottom is: garbage, woven geotextile, drainage layer, geotextile, HDPE geomembrane, protective layer, base. This is the most common anti-seepage structure and has the characteristics of economical benefits.
2. Composite anti-structure:
The composite anti-seepage structure from top to bottom is: garbage, woven geotextile, drainage layer, geotextile, HDPE geomembrane, GCL bentonite blanket, and base. Compared with ordinary single-layer anti-seepage structure, it has better anti-seepage effect.
3. Double-layer anti-seepage structure:
The double-layer anti-seepage structure from top to bottom is: garbage, woven geotextile, drainage layer, geotextile, upper HDPE geomembrane, geocomposite drainage network, lower HDPE geomembrane, protective layer (clay or geotextile), base, using The double-layer HDPE landfill geomembrane enhances the anti-seepage effect, and the drainage network between the two layers of geomembrane can play the role of leakage detection and sewage removal.
4. Sealing and anti-seepage structure:
The anti-seepage structure of the closed site from top to bottom is: vegetation greening, nutrient soil, backfill soil, drainage layer, geotextile (geotextile may not be used when the drainage layer adopts a composite drainage network), HDPE geomembrane, gravel exhaust layer, garbage . The closure system can prevent rainwater from continuing to wash away wastes and continuously generate sewage, reducing the amount of sewage treatment; vegetation greening or comprehensive utilization of the site can be carried out on the cover film.
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