Stirring4AD. Impact of agitator design on anaerobic digestion performance: Assessing digestate management and gas production at increased mixing uniformity

The efficiency of anaerobic digestion processes is intricately tied to the quality of mixing. This research aims to investigate the influence of two agitator types, namely a helical ribbon and pitched-blade impeller, on key aspects of anaerobic digestion. The investigation encompasses mixing dynamics, methane production, microbial communities, and the previously unexplored impact on digestate dewaterability. Results show that agitation with the pitched-blade impeller exhibited stratification, but the methane yield remained unchanged. Slower mixing with the helical agitator achieved more uniform mixing and reduced energy requirements. Additionally, it was found that the agitator type also affects digestate dewaterability. Specifically, the pitched-blade impeller shows enhanced dewaterability performance. These findings highlight the importance of considering digestate dewaterability for optimized anaerobic digestion efficiency.