Integrated AD and Tunnel Composting for Household, HORECA1 and Green Biowaste Streams

This technology combines anaerobic digestion (AD) with tunnel composting to recover value from municipal biowaste. Organic waste from households, small businesses and the hospitality sector can be transformed into biogas and nutrient-rich compost, supporting circular waste management and sustainable agriculture.

Biowaste is first treated in an anaerobic digestion process to produce biogas, and the remaining material is then composted in controlled tunnels. The process ensures hygienisation, stabilisation and the recovery of nutrients that can be returned to the soil as compost.

Turning Organic Waste into Energy and Compost: the process

The system integrates anaerobic digestion and tunnel composting in several steps:

Collection and inspection of biowaste from municipal separate collection (household bio-bins), including food scraps, garden waste and other biodegradable materials, as well as organic biogenic waste from small businesses. Feedstock quality requirements are applied before processing.
Physical pre-treatment, such as screening, before the material is fed into the anaerobic digestion unit.
Anaerobic digestion, where biowaste is converted into biogas. The process operates under thermophilic conditions at 55 °C for 14 days.
Mixing with green waste and transfer to composting tunnels.
Tunnel composting, where the material undergoes hygienisation and stabilisation under controlled temperature profiles (e.g. 55 °C for 2 weeks, 60 °C for 6 days, or 65 °C for 3 days, according to German Biowaste Ordinance requirements).
Sieving and removal of inert materials such as plastics or metals.

Many steps are automated, including shredding, sieving, material transport through conveyor belts, fermentation control, and ventilation within the composting tunnels. Rainwater is used to meet water needs, meaning no fresh water consumption is required. The compost can be applied within existing agricultural systems.