Constructed Wetland Wastewater Treatment Project (Filament Non-woven Geotextile)
Constructed Wetland Wastewater Treatment Project (Filament Non-woven Geotextile)
1. Project Background
This is a constructed wetland for urban tail water treatment with multi-stage filter beds. The fillers are layered: gravel drainage layer at the bottom, zeolite / volcanic rock adsorption layer in the middle, and planting soil on the top. Without separation and filtration layers, the topsoil will continuously leak downward and clog the gravel, leading to rapid failure of the wetland. Clogging will raise the water head and reduce treatment efficiency.
2. Geotextile Specification & Consumption
Type: Filament needle-punched non-woven geotextile
Specification: 300 g/m², O₉₅ ≤ 0.09 mm, high permeability coefficient, resistant to microbial corrosion
Net laying area: 16,800 m²; wastage rate: 6%, total procurement quantity: 17,800 m²
3. Functions & Performance of Geotextile
✅ Separation + Filtration + Drainage
It separates planting soil from the gravel filter layer. Wastewater can infiltrate downward while soil particles are retained, protecting the voids of gravel from clogging. Meanwhile, it forms a horizontal water-conducting layer between filler layers to distribute water evenly and avoid short-circuit flow.
✅ Outcome: The wetland has operated continuously for many years without large-area clogging of filter beds. Uniform water distribution ensures stable removal of COD and ammonia nitrogen.
4. Construction Parameters
Laying: Manual deployment, flat and wrinkle-free; relaxation rate: 1%～2%.
Overlap: ≥ 25 cm; the upstream sheet overlaps the downstream one following water flow. Overlap is preferred for joints, and sewing is adopted for a small number of positions.
Fixation: Stabilized by sand bags. Fillers shall be backfilled in layers as soon as possible after laying to reduce aging caused by sunlight exposure.
Quality control: Backfill from low to high elevation, spread lightweight materials. Heavy machinery is prohibited from walking directly on the geotextile.
5. Coordination with Other Measures
Geotextile: Interlayer separation and filtration, preventing filler mixing and clogging;
Gravel drainage layer + perforated collection pipes: Collect treated effluent;
Zeolite / volcanic rock filler: Adsorb and biodegrade pollutants;
Emergent plants: Purify water and reoxygenate through root systems.
