Limited infrastructure
Decentralised sites often lack sewers, reliable energy supplies and organised disposal routes for biogenic residues.
Mobile and modular bioenergy technology
Mobile biogas plant for decentralised sites
The modular plant treats faecal sludge, biogenic household waste and comparable residues even at sites with limited or no municipal infrastructure. Transportable process modules, multi-stage anaerobic digestion and gravity- and gas-pressure-assisted media transfer reduce mechanical energy demand and create the conditions for largely energy-autonomous operation.
Initial challenge
Safely utilise biogenic residues even where infrastructure is limited
High internal energy demand
Conventional pumps, agitators and gas compressors make energy-autonomous and economical operation difficult for small plants.
Hygiene and emissions
Faecal sludge, kitchen waste and food residues require closed hygienising treatment to prevent odours, greenhouse-gas emissions and water pollution.
Changing volumes and locations
Varying material volumes and deployment sites require prefabricated, transportable and modularly expandable plant components.
Operating principle
Multi-stage digestion with gravity- and gas-pressure-assisted media transfer
Prepare the biosuspension
The biogenic feedstocks are fluidised, shredded and homogenised with process liquid in a reception vessel to form a biosuspension for wet digestion.
Mesophilic main digestion
The first anaerobic stage operates as a culture-retaining continuous-flow digester under mesophilic conditions and stabilises methane formation with varying feedstock qualities.
Thermophilic post-digestion
At least two downstream vessels operate in batch mode under thermophilic conditions, supporting minimum treatment times and full-flow hygienisation.
Gravity-assisted substrate transfer
Process vessels arranged at different elevations and controlled valves enable liquid fermentation substrates to be transferred largely without additional pumps.
Biogas as a circulation medium
Biogas from upstream vessels is introduced near the bottom of downstream stages. Its own pressure assists substrate circulation and gas transport without continuously operating agitators or compressors.
Gas and fertiliser utilisation
Biological pre-desulphurisation takes place in the digestate tank. The biogas can be used in a CHP unit or gas boiler, while phase separation produces liquid and solid organic NPKS fertilisers.
Design features and benefits
Transportable process modules with low mechanical effort
Containerised process modules
The transportable components do not exceed the maximum dimensions of standard transport containers and can largely be equipped at the factory.
Vertically staggered vessel arrangement
Vessels for successive treatment stages are positioned at different elevations so that hydrostatic pressure can be used for media transfer.
Pressure-resistant gas spaces
Gas-tight process vessels with graduated permissible overpressures enable biogas to pass through several process stages and to be used for circulation.
Watertight installation area
A trafficable, drain-free and watertight surface with a surrounding upstand forms a containment area and supports preventive water protection.
Low mechanical effort
Gravity, hydrostatic pressure and the biogas's own pressure replace a substantial share of the pumping, agitation and compression work otherwise required.
Flexible and energy-autonomous use
The combination of high biogas yield and reduced internal energy demand supports largely energy-autonomous operation at temporary or permanent decentralised sites.
Illustrative design data
Three illustrative plant configurations
Faecal sludge
4.0 m³ feedstock per day · 39.5 m³ methane per day · 10 kWel CHP · 3.9 m³ liquid fertiliser per day
Kitchen and food waste
2.6 t feedstock per day · 376 m³ methane per day · 0.7 t solid fertiliser and 1.25 m³ liquid fertiliser per day
Kitchen and food waste (expanded plant configuration)
5.2 t feedstock per day · 823 m³ methane per day · 1.1 t solid fertiliser and 3.5 m³ liquid fertiliser per day
These values are not generally applicable performance guarantees; actual design depends in particular on material volume, composition, dry-matter content and site conditions.
Technical background
The technical solution presented is based on the published international patent application WO 2022/096048 A1. Vessel sizes, pressure ratings, materials, safety and permitting requirements, and the design for the respective feedstocks must be assessed for each project and site.
Technical project assessment