Investigation of the mixing behaviour of a full-scale biogas plant using biodegradable tracers

This work studied the mixing processes in the full-scale research biogas plant of the University of Hohenheim by applying a biodegradable tracer. Two different mixing setups were used to gain a deeper insight into the mixing processes in a continuous stirred tank reactor (CSTR) equipped with mechanical agitators. For this study, a submersible motor mixer and a propeller incline shaft agitator were used to investigate the importance of pro-peller correspondence. The mixing behaviour of the two variants was shown to differ greatly. By using two mixers simultaneously, mixing times and energy consumption could be strongly reduced (up to 30 times). Thus, both electricity demand and attrition of the stirrers can be lowered.