Biogas Digester Geomembrane: Technical Specifications and Installation Guidelines

Material Selection

1. HDPE Geomembrane (1.0-2.0mm thickness)

• UV-stabilized formulations (≥97% carbon black)

• Chemical resistance: pH 0.5-14

• Permeability: <10⁻¹² cm/s (ASTM D5887)

2. Reinforced PVC Membrane (0.75-1.5mm)

• Puncture resistance: ≥500N (ASTM D751)

• Flexible for complex digester shapes

Key Functions

✔ Gas Containment

• Methane retention efficiency: ≥99.5%

• Operating pressure: 5-15kPa

✔ Seepage Prevention

• Reduces nutrient loss by 90% vs. unlined ponds

✔ Structural Support

• Withstands 3-5% substrate settlement

Installation Protocol

1. Base Preparation

• Achieve 95% Proctor density with ≤20mm surface irregularities

• Install 300g/m² geotextile cushion layer (for puncture protection)

2. Welding Techniques

• Dual Hot Wedge (HDPE):

• Temperature: 300-350°C

• Speed: 1.5-2.5m/min

• Seam width: 25-40mm

• Hot Air (PVC):

• 400-450°C with pressure rollers

3. Quality Control

• 100% seam testing:

• Vacuum test (@ 25kPa)

• Spark test (15-25kV)

• Anchor Trench:

• 0.8m (D) × 0.5m (W) with concrete backfill

Performance Data

▸ Service Life: 20-25 years (HDPE), 15-20 years (PVC)
▸ Temperature Range: -40°C to +80°C
▸ CO₂ Emission Reduction: 5-8 tons/year per 500m³ digester

Title: "Geomembrane Solutions for Biogas Digesters: Design and Performance Optimization"

Maintenance Requirements:

• Annual inspection for UV degradation (≤10% tensile strength loss)

• Biogas leakage monitoring (<1% volume loss/day)

Cost Analysis:

• $8-15/m² installed (material + labor)

• ROI Period: 2-3 years through gas recovery

Standards Compliance:
✔ DIN EN 13967 - Flexible tank liners
✔ NSF/ANSI 61 - Potable water contact