Valorgas project

AeroThermal has made a major contribution to a study examining the effectiveness of various pre-treatments to enhance the bio-methane yield from food waste.  Our contribution was to examine the effect of autoclaving on the digestibility of food waste.

The studies, which were partially funded by the EU, included small scale tests in Finland on material processed in our pilot scale autoclave in Poole, and larger scale tests over an extended period of time in a Biogen Greenfinch digester at Ludlow.

The latter tests required the regular autoclaving and transportation of substantial quantities of source-segregated food waste which was supplied to AeroThermal by Eco Sustainable Solutions from its base at Hurn.

These tests have shown consistent results and have concluded that autoclaving has a number of beneficial effects on food waste which is destined for use as a feedstock for anaerobic digestion.

The key benefits are:

• Lower ammonia concentrations
• Lower VFA concentrations
• Lower H2S concentrations
• Reduced pathogen levels
• High digester loading rates without the addition of trace elements
• Removing the requirement for shredding, sorting and pasteurisation

This project concluded that autoclaving, using the AeroThermal methodology, is particularly suitable for:

• Thermophilic digestion where trace element addition is less effective
• Feed stocks with high protein content
• Poorly sorted and contaminated feed stocks