Selected Biogas Case Studies
How it works
The Landia GasMix Chopper Pump draws digestate from the bottom of the digester, chops solids, and recirculates the digestate to create both horizontal and vertical flow inside the tank. This process enhances digestion efficiency and helps prevent clogging in pumps, pipes, and nozzles. The Landia GasMix pumps are strategically positioned to generate crossflow circulation,
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reducing dead zones and ensuring even distribution of solids and temperature throughout the digester. Each pump draws digestate from the bottom and injects it sequentially through nozzles placed at different heights in the tank. This provides horizontal movement at multiple levels, while the highest injection point helps break and prevent the formation of a crust layer.
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Mixing nozzle
Wall connection flange
Diffuser
Wall connection flange Ejector PVC nozzle
Oil container Pump assembly
Wall connection flange
Mixing nozzle
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Why Choose Landia GasMix? • 100% gas-tight system No loss of methane or CO2
• Easy service and routine maintenance Fewer man-hours required
• Improved health & safety No personnel working in the gas zone
• No gas leaks or temperature drop During maintenance
• Landia chopper pump technology
Effective solids reduction - prevents clogging
• Lower investment costs Reduced demands on tank construction
• Minimal space required for service
Compared to other digester mixers
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Landia GasMix
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Hot Tap Drilling Installation for Zero-Downtime Digester Upgrades The Landia GasMix system can be installed without emptying the digester, as all work is carried out externally. This allows the digester to remain in operation throughout the installation process, eliminating downtime and avoiding loss of production.
A sealing arrangement is then applied to ensure a secure and leak-tight connection, after which the system is inserted without the need to open or empty the digester. The result is a fast, safe and cost-efficient installation with minimal environmental impact.
Installation begins with positioning the tank wall connections, followed by controlled drilling through the tank wall.
• No Downtime • Cost-Efficient • Safe and Quick Installation • Environmental Benefits
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More Efficient Biogas Production.
Food Wasteto-Energy LOCATION: United Kingdom
A food waste-to-energy operation improved the performance of its biogas process after installing a Landia digester mixing system. The facility needed a more robust solution for its second digester, where unpredictable food waste feedstock, high dry solids and the risk of foam, blocking and crust formation required reliable mixing. Landia’s externally mounted pump/mixing system uses chopper pump technology and venturi nozzles to reduce particle size, keep solids in suspension and support stable gas production. Compared with the existing mixing setup, the Landia solution helped create a more efficient process with improved mixing, reduced maintenance requirements and lower parasitic load.
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Results: • More efficient digester mixing, supporting a more stable biogas process.
• Better suspension of solids through external pump mixing and nozzle recirculation.
• Improved handling of variable food waste with high dry solids content.
• Lower parasitic load through interval operation instead of continuous mixing.
• Reduced risk of crust formation, blocking and foam inside the digester.
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• Easier service with equipment outside the digester. www.landiaworld.com
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Better Mixing. Stronger Biogas Performance.
AFBI Hillsborough, Agricultural biogas LOCATION: Northern Ireland
The Agri-Food and Biosciences Institute in Hillsborough needed to improve the performance of its anaerobic digestion plant, where poor digestate mixing and digestate build-up had begun to affect biogas production. To improve circulation and process stability, AFBI retrofitted the main digester with a Landia GasMix system. The externally mounted system combines a chopper pump
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with venturi nozzles, creating both hydraulic and biogas mixing without mechanical equipment inside the tank. The system helped improve mixing in the primary and secondary digestion tanks, reduce digestate build-up and support more stable biogas production. The external installation also improved service access, with no need for maintenance work inside the gas zone.
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Results: • Improved mixing in the primary and secondary digestion tanks.
• Cow slurry and grass silage were handled more effectively.
• Digestate build-up in the tanks was reduced.
• The system supported more consistent biogas production.
• Digester circulation became more stable.
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• Maintenance could be carried out from outside the digester.
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Six Years. One Reliable Mixing System.
Energy & Recycling Facility LOCATION: Northern England
At a major Energy & Recycling Facility in northern England, Landia’s GasMix system has delivered six years of uninterrupted service in two large anaerobic digesters. The facility treats thickened sewage sludge and plays an important role in the water company’s sludge treatment and renewable energy strategy. To support stable gas production, the digesters require reliable mixing that keeps solids in suspension, reduces particle size and prevents crust formation. 10
Landia GasMix
Landia GasMix is installed externally, with all mechanical equipment located outside the digester. The system uses Landia’s chopper pump technology to draw thick sludge from the bottom of the tank, reduce solids and recirculate the material through the digester for effective mixing. After years of continuous operation, the system has proven to be a reliable and easyto-service solution for demanding municipal sludge treatment.
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Results: • Six years of uninterrupted GasMix service. • Consistent support of the facility’s gas production target. • Comprehensive mixing of two large digesters.
• Solids kept in suspension to help prevent crust formation. • Reduced particle size to support the digestion process. • Easy maintenance with mechanical equipment outside the digester.
• Plant type: Municipal Sludge / Biogas Digesters: Digester volume
2 x 7,306 m3
Substrate characteristics
Thickened sewage sludge
Gas production target
22,000+ Nm³/day
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Manure-based biogas
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Homogeneous Biomass. Better Process.
LOCATION: Denmark
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At Haerup Biogas in northern Denmark, the biomass in the digester was previously thick, high in dry solids and difficult to keep homogeneous. The installation of Landia GasMix combined with Landia chopper pumps improved circulation and particle reduction, creating a much more homogeneous medium throughout the reactor. Effective treatment directly inside the reactor finely chops and homogenises the biomass. This creates optimal conditions for biogas bacteria while reducing downstream mixing demand, significantly lowering both operating time and energy consumption.
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Results: • More homogeneous biomass
• More effective treatment inside the reactor
• Improved handling of high-solids media
• Reduced mixing demand in downstream stages
• Reduced floating layers
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Future-Proofing Farm Biogas. Rybjerggaard Straw-rich biogas LOCATION: Denmark
At Rybjerggaard, the focus has long been on energy savings, self-sufficiency and making better use of the farm’s own resources. To support this, Jens Christensen built a modern biogas plant designed to handle a wide range of agricultural feedstocks. The plant processes straw, deep litter, grass, beet and corn in large quantities, while keeping nutrients on the farm and supporting the goal of becoming CO2-neutral. Landia GasMix was selected because it matched the plant’s simple and servicefriendly concept. All mechanical components are located outside the tank, so the system can be serviced without opening the reactor. The GasMix system supports mixing, shredding and homogeneous distribution of dry matter inside the reactors. According to Jens Christensen, the system has helped prevent floating layers and create strong movement in the tanks, even at high dry matter content.
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Results: • Strong mixing of high dry matter biomass. • Homogeneous distribution inside the reactors. • No visible floating layer through the viewing ports. • Good surface rotation and active gas release. • Service-friendly operation with equipment outside the tank. • Flexible operation with options to adjust mixing time and performance.
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Restoring Performance at a Food Waste AD Plant.
Food waste biogas plant LOCATION: United Kingdom
As part of a major plant overhaul, the primary digester was drained and upgraded with new Landia submersible mixers and chopper pumps. The equipment was selected for its durability, service access and suitability for demanding AD applications. The new installation improved mixing, feeding and overall process stability. With easier maintenance and more reliable equipment, the plant was able to manage a
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wider range of feedstocks more effectively and support stronger biogas production.
• More stable and continuous operation.
The main challenge was outdated equipment that was difficult to service. Previous mixers could not be maintained easily, which contributed to downtime and reduced process efficiency.
• Improved mixing in the primary digester.
Results:
• Better feeding and handling of varied feedstocks.
• Improved biogas production after the plant upgrade.
• Reduced operational challenges and downtime.
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Reliable Mixing for Palm Oil Biogas. Palm oil mill effluent LOCATION: Thailand
In southern Thailand, Landia has installed a Landia GasMix digester mixing system for one of Asia’s leading producers of sustainable palm oil. The system is installed on two glass-lined bolted tanks, each with a volume of 6,450 m³ and a diameter of 28 metres. The tanks process palm oil mill effluent, also known as POME, with approximately 5% total solids. Landia GasMix is externally mounted and positioned to provide comprehensive mixing inside the digesters. The installation includes an ejector/diffuser at intermediate height, JetMix mixing nozzles near the base of the tanks and a higher crust-breaking nozzle. The customer had already installed Landia GasMix on its first digester in 2021, and the new project builds on proven performance, low maintenance and strong operational trust.
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Results: • Comprehensive mixing of palm oil mill effluent. • Improved process support through multiple nozzle levels. • Low-maintenance operation with equipment outside the digesters.
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Landia A/S Industrivej 2 DK-6940 Lem St. tel. +45 97 34 12 44 info@landia.dk