Autoclave designer and manufacturer AeroThermal Group has claimed that the throughput of anaerobic digestion (AD) plants could double with use of an autoclave.
Its research finds that pre-treating food waste with the technology – which subjects it to stream and pressure – can boost throughput while reducing ammonia concentrations.
The company, which has been running trials for 18 months, found that digester performance was maximised when the autoclave operated at 140°C and the digesters were run at an organic loading rate of more than 5kgVS/cu m/day.
Stable operations have been achieved at a loading rate as high as 10kgVS/cu m/day with food waste autoclaved at 140°C, while un-autoclaved feedstock digesters entirely failed at a loading rate of 5kg VS/cu m/day.
AeroThermal said the increases in digester performance can be attributed to the denaturing of protein during autoclaving pre-treatment, which has the effect of reducing the quantity of ammonia generated.
The company believes that AD plant operators could potentially double revenues for only a marginal increase in operating costs since the autoclave uses waste heat from the combined heat and power process.