Biogas plant sealing describes the construction of watertight containment barriers around anaerobic digestion (AD) plants, digestate tanks, and slurry stores. Aggressive process liquids including digestate, slurry, and hydrogen sulphide condensate can contaminate groundwater if containment fails. Carbofol® geomembranes and Bentofix® geosynthetic clay liners (GCL) provide long-lasting, regulation-compliant barrier systems for all containment zones.
Naue geosynthetic sealing systems are deployed wherever liquid containment, groundwater protection, and regulatory compliance are critical in renewable energy infrastructure.
Secondary containment for liquid digestate against groundwater infiltration
Sealing systems for agricultural anaerobic digestion facilities
Biogas containment systems are installed in challenging site conditions: slopes, confined bunded areas, and substrates subject to settlement. Carbofol geomembranes and Bentofix GCLs are designed to withstand installation loads and provide reliable long-term performance even under continuous chemical exposure from digestate and process liquids. The right sealing system depends on the type of containment zone, the chemical load and the substrate conditions.
The design of geosynthetic sealing systems for biogas plants is based on recognised national and European standards. The system must comply with the applicable regulatory framework (AwSV, TRwS and WHG in Germany; EA guidance in the UK) and be specified for the project-specific chemical and mechanical loads.
Slurry silos, liquid manure stores, and silage seepage systems
Large-scale industrial biogas and biomethane plants
Practical benefits:
Biogas plants handle substances classified as hazardous to water under AwSV (Germany) and equivalent EA guidance (UK). A robust sealing system must prevent the migration of digestate, slurry and other process liquids into the subsoil. The specification depends on the containment zone and the regulatory framework.
Key principle: A geomembrane provides the primary chemical barrier. A GCL provides self-healing secondary containment. Together, they form the compliant composite system required by AwSV and TRwS.
Product selection depends on the containment zone, chemical load, substrate type, and applicable regulation. The table below provides a structured decision guide across key criteria.
Additional guidance: For all installations subject to AwSV (Germany) or EA guidance (UK), the composite system (Carbofol® + Bentofix® + Secutex®) is recommended as the standard specification. Use the Naue Portal software tools or contact Naue’s engineering team for project-specific design.
| Criterion | Carbofol® (geomembrane) | Bentofix® (GCL) | Combined system |
|---|---|---|---|
| Substrate type | Concrete/compacted soil | Earthworks/natural ground | Both/complex substrate |
| Chemical exposure | High (digestate, H2S, organic acids) | Moderate chemical suitability only: NH4+ (ammonium) present in digestate can displace Na+ ions in standard sodium bentonite, causing an irreversible permeability increase. For high-ammonium digestate, specify Bentofix® X (polymer-coated grade). Verify GCL compatibility with site-specific digestate chemistry before specification. | High + self-healing redundancy |
| Filtration/self-healing | No (synthetic barrier) | Yes (bentonite self-seals) | Yes (GCL backup layer) |
| Slope applicability |
Regulatory compliance
Carbofol® and Bentofix® systems are approved to BAM, CE-marked, and conform with EN 13492. This ensures compliance with AwSV, WHG, and TRwS requirements from the outset and reduces approval risk.
Long service life
Carbofol® geomembranes have a long, proven track record in containment applications. High stress-crack resistance (ASTM D5397), UV resistance, and chemical stability ensure long-term performance with minimal maintenance costs.
Verifiable barrier performance
Bentofix® GCL achieves a hydraulic conductivity of k ≤ 5 x 10-11 m/s. The composite system provides redundant containment: if the geomembrane is locally damaged, the self-healing GCL prevents liquid migration.
Single-source system solution
Naue supplies the complete sealing system: geomembrane, GCL, protective geotextile. Technical design support and installation services are also available. A single-source system reduces coordination effort and ensures system compatibility.
Biogas plant sealing describes the construction of impermeable containment barriers around anaerobic digestion plants, digestate storage lagoons, and slurry tanks. Containment is legally required under AwSV (Germany) and equivalent Environment Agency guidance (UK) to prevent process liquids from contaminating groundwater. Geosynthetic systems provide the most economic and reliable compliant solution.
The choice depends on the containment zone, the chemical load and the applicable standard. Carbofol® HDPE geomembrane is specified where primary chemical resistance is required. Bentofix® GCL is added as a secondary mineral layer where AwSV composite system requirements apply. Secutex® provides mechanical protection. You can find digital geotechnical selection and design tools in the Naue Portal or contact Naue for project-specific advice.
In Germany, the key regulations are the Water Resources Act (WHG), the Ordinance on Installations for Handling Substances Hazardous to Water (AwSV) and the Technical Rules for Substances Hazardous to Water (TRwS). Gas tightness for methane (CH4) emissions is additionally governed by TA Luft and the 4th Federal Immission Control Ordinance (4. BImSchV), since methane is both a potent greenhouse gas and an explosive hazard. Relevant product standards include EN 13492 for geosynthetic barriers (geomembranes and GCLs). BAM approval applies for installations in Germany. In the UK, EA CIRIA guidance applies.
Geosynthetic systems typically reduce installation time and labour costs compared to cast-in-place concrete lining. Material handling is simplified: Carbofol® panels up to 7.5 m wide reduce the weld count; Bentofix® requires no sealant at overlaps. Long service life and minimal maintenance reduce whole-life costs.
The lining system is installed in layers on a prepared substrate. Bentofix® GCL is unrolled and overlapped and the bentonite-impregnated borders provide self-sealing at joints. Carbofol® geomembrane panels are then installed and welded using hot-wedge or extrusion welding. Secutex® can be placed above or below for mechanical protection. All weld seams are tested in accordance with the project specification.
Yes. Carbofol® geomembranes are CE-marked and approved by BAM for containment applications in Germany. Bentofix® GCL fulfils the LAGA certificate of suitability requirements for German waste and containment regulations. For UK projects, products conform with EA guidance for digestate and slurry containment.
Yes. Naue supplies the complete system: Carbofol® geomembrane, Bentofix® GCL, and Secutex® protection geotextile. Technical support, stability assessment and design assistance are available from Naue engineers. This single-source approach reduces coordination risk and ensures layer compatibility. Further service offered by Naue is the laying and installation by a certified team.
Carbofol® weld seams are tested using air pressure channel testing (wedge weld), spark testing, or peel/shear destructive testing in accordance with the project specification and applicable standards (e.g. DVS 2226, ASTM D6392). All test results are documented in a quality assurance record. Naue provides technical support for weld specification and on-site quality control procedures.
Naue Bentofix® NSP 4900 is a needle-punched geosynthetic clay liner (GCL) with a bentonite-impregnated border on all four edges. This provides self-sealing performance at overlaps without additional sealant. The hydraulic conductivity of k ≤ 5 x 10-11 m/s exceeds typical GCL performance requirements for AwSV compliance. The needle-punched structure ensures high interface friction, making it suitable for slope applications in digestate lagoons and bunded containment areas.
Naue Carbofol® is a HDPE liner for landfill sealing, mining containment, and groundwater protection.
Naue Bentofix® is a geosynthetic clay liner (GCL) for waterproofing in landfill engineering, groundwater protection and hydraulic applications.
Naue Secutex® is a mechanically bonded nonwoven geotextile for separation, filtration and protection in roads, railways and hydraulic engineering projects.
| Embossed surface for slopes |
| High-friction needle-punched GCL |
| Both: slope-stable solution |
| Recommended product | Carbofol® HDPE 1.5 - 2.5 mm | Bentofix® NSP 4900 | Carbofol® + Bentofix® + Secutex® |
| Compliance reference | EN 13492, BAM approval | GRI-GCL3 | AwSV/TRwS composite system |