CONCENTRATION PROFILES IN ROTATING-DISC REACTORS - THEIR MATHEMATICAL-MODEL FOR THE ANAEROBIC-DIGESTION OF ACETIC-ACID INCLUDING AN EXPERIMENTAL-VERIFICATION

This paper presents rotating disc reactors for aerobic and anaerobic w astewater treatment. Unlike the activated sludge or contact processes, this reactor allows higher concentrations of biomass and lesser dange r of the reactor becoming blocked. The reduced backmixing within the r eactor leads to axial concentration profiles when continuously operate d. These are presented for various biological processes. The axial con centration pro-files generated during the continuous anaerobic degrada tion of acetic acid are measured and described by a mathematical model . A refined dispersion model is created on the basis of tracer experim ents taking into account the actual construction of the reactor as wel l as the physical conditions in it. To determine the biodegradation a Haldane kinetics is used, in which the undissociated acetic acid is th e substrate. The model takes into consideration all the local paramete rs (pH value, concentration of acetic acid biomass, and ion activity). The difficult measurement of the concentration of the active biomass which is immobilized on the disk is accomplished by carrying out batch experiments. The results of the experiments are 22 concentration prof iles with influent DOC concentrations from 200 to 2000 mg L-1 which we re measured and modelled. Some examples are shown to illustrate the in fluence of the ion activity and the refinement of the dispersion model .