Digester Mixing System
Cases & References for GasMix Solutions
Why Choose Landia GasMix?
• Completely External Installation No moving parts inside the digester
• Easy Access and Maintenance Fewer man-hours required
• Improved health & safety
No personnel working at heights or in the gas zone
• Lower Lifecycle Cost
Reduced demands on tank construction
• Landia Chopper Pump Technology
Effective solids reduction - prevents clogging
• Improved Digester Performance Increased VS destruction
• Ideal for New Installations and Retrofits Alike
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Landia GasMix
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Tuas STW, SG
Client: PUB Singapore Consultant: Jacobs
Digesters: Digester diameter
82 ft
TWL (sludge level)
105 ft
Digester volume
2.66 MG
TS
5.4 %
No. of tanks
8
Image Credit: Jacobs and PUB, Singapore’s National Water Agency
Vimercate, IT Digesters: Digester diameter
59 ft
Height
33 ft
Digester volume
0.66 MG
TS
3-4 %
No. of tanks
1
Tank type
Steel
Taeyoung, KR Digesters: Digester diameter
66 ft
Height
59 ft
Digester volume
1.32 MG
TS
6-7 %
No. of tanks
2
Landia GasMix
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Increase digester efficiency.
Sparta WWTP LOCATION: United States
The City of Sparta operates a wastewater treatment plant serving around 10,000 residents and several industrial contributors. To improve biogas production and reduce maintenance issues, the plant upgraded its digester mixing with the Landia GasMix system. Poor mixing from the existing air-based system had led to debris buildup, reduced digester efficiency, and costly maintenance that required tank drainage. Landia GasMix was installed as an external mixing solution, using a chopper pump and venturi nozzles to deliver full-tank mixing with all mechanical components located outside the digesters. The upgrade resulted in a 25 % increase in biogas production, more stable digester temperatures during winter, reduced downtime, and improved digestate quality for agricultural reuse.
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Landia GasMix
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• Plant type: Municipal WWTP with industrial influent Digesters: Primary
0.33 MG (333,913 gal)
Secondary
0.18 MG (183,071 gal)
Key benefit
Full-tank mixing with no internal mechanical components
Results: • +25 % biogas yield through improved breakdown of volatile solids
• Improved digestate quality, reused locally as a nitrogenrich fertilizer
• Stable digester temperatures, even during cold Wisconsin winters
• Reduced energy costs, driven by higher and more consistent biogas production
• Lower maintenance and downtime, with all mechanical components accessible outside the tanks
Landia GasMix
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Digester Mixing System
Better Mixing. Higher Biogas Yield.
Nigg Wastewater Treatment Works LOCATION: Scotland
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Nigg Wastewater Treatment Works, operated by Scottish Water, has become a leading site for biogas production from sewage sludge.
The new system provides reliable mixing of the two 1.06-MG digesters while using significantly less energy than conventional mixing methods.
To improve efficiency and energy recovery, the facility upgraded its thermal hydrolysis process and installed a Landia digester mixing system.
Together with the process upgrade, the improved mixing has helped optimise sludge digestion and increase biogas production, turning the site into a strong producer of renewable energy.
Landia GasMix
www.landiainc.com
Digesters: Digester diameter
56 ft
Digester height
66 ft
Volume
1.06 MG
Substrate
Sewage sludge
Tank type
Concrete
Landia GasMix
www.landiainc.com
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Say goodbye to poor mixing.
Damhusaaen WWTP LOCATION: Denmark
After the failure of a top-mounted mixer at the Damhusaaen wastewater treatment plant, BIOFOS – Copenhagen’s leading utility company – needed a reliable replacement for one of the plant’s digester tanks. The existing mixer required extensive upgrading, which would have caused downtime and increased safety risks.
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Landia GasMix
Instead, BIOFOS chose the Landia GasMix system, an externally mounted solution that recirculates biogas and sludge to ensure efficient mixing without internal mechanical components. The system was installed on a full tank using the Hot Tap Drilling method, eliminating the need to empty the digester and minimizing operational disruption.
www.landiainc.com
Results: • Short installation time compared to alternative solutions • Full operation achieved after 14 days – compared to up to 4 months
• Screenings effectively reduced by the cutting system, improving downstream handling • Stable operation with 100 % uptime for nearly 3 years
• Total installation costs significantly lower than a 1:1 replacement
• Plant type: Municipal WWTP Digesters: Digester diameter
55 ft
Digester volume
2.01 MG
Substrate characteristics
sludge from WWTP
Average TS, input
4 % TS
Landia GasMix
www.landiainc.com
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Digester Mixing System
One Upgrade. Big Results. Gigablok WWTP LOCATION: Poland
To improve efficiency and reduce operating costs, the plant needed to replace its outdated digester mixing system, which had led to insufficient mixing and unstable process conditions. Gigablok therefore upgraded to a Landia GasMix system, where all mechanical components are located outside the digestion chamber, eliminating the risk of internal mechanical failures. The installation was completed without emptying the chambers, minimizing both costs and operational downtime.
Results: • More stable fermentation process • Improved sludge decomposition • Reduced risk of process disruptions • Lower installation impact
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Landia GasMix
www.landiainc.com
When mixing finally works. Dabrowa Gornicza WWTP LOCATION: Poland
Digesters:
In February 2026, Landia successfully finalized a mixing system upgrade project at another wastewater treatment plant in Poland. The facility Dabrowa Gornicza operates three anaerobic tanks, each55 ft high, 464,150 gallons. One of the digesters had begun showing signs of reduced process efficiency due to inadequate mixing. The existing mixing equipment had become outdated, resulting in poor circulation and process instability.
Landia GasMix
Digester diameter
46 ft
Height
55 ft
Digester volume
464,150 gal
TS
2-3 %
No. of tanks
3
To address this issue, the customer decided to install a Landia GasMix system in the affected tank. The system was commissioned and operational within a short timeframe. Already within the first month of operation, the plant reported significantly improved mixing performance and overall process stability. The results have been sufficiently positive that the customer is now considering upgrading the mixing systems in the two remaining anaerobic tanks as well.
www.landiainc.com
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Simplicity at Low Power Demand.
Kawana STW LOCATION: Australia
The digester is equipped with a single Landia GasMix mixer with an installed motor power of 18.5 kW. The system operates intermittently (on/off), providing reliable mixing and circulation of the digester contents. Actual power consumption during operation is approximately 7-8 kW.
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Landia GasMix
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Kawana Sewage Treatment Works is a major wastewater treatment facility on the Sunshine Coast in Queensland, Australia, serving areas such as Maroochydore, Mooloolaba, and Kawana. It treats municipal wastewater before the treated water is released or reused. Digesters: Digester diameter
33 ft
Digester height - total
38 ft
Volume
211,338 gal
Substrate
Waste activated sludge
TS
3-4 %
Type of tank
Concrete
Landia GasMix
www.landiainc.com
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Smarter Digester Mixing. Radegast WWTP LOCATION: Germany
In cooperation with Landia, ReTech Resources Technology has installed an external sludge recirculation system in Germany. By placing all mechanical components outside the digester, maintenance becomes safer and easier, while equipment is protected from corrosion and wear. The system improves process stability and energy efficiency, supported by modern sensors for precise monitoring and control. In addition, ReTech Resources Technology has developed a separator for hair, fibres and microplastics. This patented unit is installed upstream of the digester, removing inorganic materials before the sludge enters the tank. The result is better use of digester volume, fewer operational disturbances, and increased biogas production.
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Landia GasMix
www.landiainc.com
Results: • Complete tank mixing without dead zones • Minimized foam formation and sediment build-up • Reduced internal power consumption • Robust and stable process performance
Landia GasMix
www.landiainc.com
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Landia, Inc. 2700 Gateway Centre Blvd, Suite 100 Morrisville, NC 27560 United States of America +1 (919) 466-0603 info@landiainc.com