Anaerobic digestion operating at approximately 35°C, the most common temperature regime for agricultural and municipal biogas operations. Floating covers retain process heat.
Mesophilic digestion is anaerobic digestion at an operating temperature of approximately 35°C — the favoured temperature range for most agricultural and municipal biogas operations because of the balance between digestion rate, process stability, and heating energy cost. For digesters operating in ambient < 15°C, surface heat loss is a significant heating budget; floating covers reduce this by 60–80%.
The heat-retention contribution of the patented hexagonal cover was specifically recognised by the US Department of Energy — see /heritage.