Characterizing mixing in a rotating drum bioreactor for solid-state fermentation

A method, based on the use of wheat bran particles dyed with Rhodamine-WT a s tracer particles, was developed to characterize mixing in a 200 l rotatin g drum bioreactor used for solid state fermentation. The extraction process contributes a 15% relative error in determining Rhodamine concentrations. Extraction efficiency is not affected by autoclaving of the bran and there is no inter-particle transfer of dye during the mixing of bran within the d rum. For an unbaffled drum rotated at 5 rpm the axial dispersion coefficien t is 9.15 cm(2) min(-1).