MASS TRANSFER MODEL FOR FIXED-FILM ANAEROBIC REACTORS

Two, two-stage, cyclic (TSC) anaerobic filter reactor systems were operated for almost two years to determine the COD removal performance under various COD loading rates and operating cycle times. A two-stage reactor system without flow reversal was used as a control. Tests indicated that the COD removal efficiency of the TSC configuration was about 15% greater than the control when operating at COD loading rates of 8 g/L-day. This improved efficiency occurred because the second stage of the control reactor system provided little additional removal. The second stage of the TSC reactor systems contained active biomass that provided substantial COD removal above that in the first stage. A mass transfer model indicated that the performance of the TSC process was controlled by hydraulic retention time rather than by biodegradation kinetics.