Parameter estimation in biofilter systems

The purpose of this research is to estimate the unknown parameters of a mat hematical model of the biodegradation of volatile organic compounds (VOCs) in a gas phase trickle-bed biofilter, using experimental results from a two -reactor pilot-scale system treating the VOC diethyl ether. The model consi ders a dynamic three-phase system, (biofilm, water, and gas), nonuniform ba cterial population, and one limiting substrate. The nonlinear parameter est imation was done in two stages: estimates of the steady-state model paramet ers were obtained first, and then, these values were used in the estimation of the remaining parameters. Experimentally obtained biofilter performance curves and batch tests were used for the estimation of the steady-state pa rameters: maximum rate of substrate utilization (mu(m)X(f)/Y), Monod consta nt (K-s), and biofilm/water diffusivity ratio for ether, r(d). Dynamic biof ilter performance data were used to obtain the estimates of the six remaini ng parameters: yield coefficient(Y). maximum growth rate (mu(m)), rate of d ecay (k(d)), rate of biomass maintenance (b), initial fraction of active bi omass (f(a0) = X-f/rho(S)), and coefficient of detachment (C-deT). Using th e biofilter performance curves, the value of mu(m)X(f)/Y was uniquely deter mined, but the estimates of the parameters K-s and r(d) were highly correla ted. High values of K(s)and r(d) gave similar results as low values of both parameters. Batch tests using the bacterial population from the reactor an d ether as the only substrate were used to determine the value of K-s witho ut diffusional interferences.