MATHEMATICAL-MODELING OF MIXING IN A HORIZONTAL ROTATING TUBULAR BIOREACTOR - SIMPLE FLOW MODEL

The construction of the horizontal rotating tubular bioreactor (HRTB) represents a combination of a ''thin-layer'' bioreactor and a ''biodis c'' reactor. The bioreactor was made of a plastic tube whose interior was divided by the O-ring shaped partition walls. For the investigatio n of mixing properties in HRTB the temperature step method was applied . The temperature change in the bioreactor as a response to a temperat ure step in the inlet flow was monitored by six Pt-100 sensors (t(90) response time 0.08s and resolution 0.002 degrees C) which were connect ed with an interface unit and personal computer. Mixing properties of the bioreactor were modeled using the modified ''tank in series'' conc ept which divided the bioreactor into ideally mixed compartments. A ma thematical mixing model with ''simple flow'' was developed according t o the physical model of the compartments network and corresponding hea t balances. Numerical integration of an established set of differentia l equations was done by the Runge-Kutta-Fehlberg method. The final mat hematical model with ''simple flow'' contained four adjustable paramet ers (N1, Ni, F-cr and F-p) and five fixed parameters.