MODELING BIOFILM ACCUMULATION AND MASS-TRANSPORT IN A POROUS-MEDIUM UNDER HIGH SUBSTRATE LOADING

A packed bed biofilm reactor inoculated with pure culture Pseudomonas aeruginosa was run under high substrate loading and constant flow rate conditions. The 3.1-cm-diameter cylindrical reactor was 5 cm in lengt h and packed with 1-mm glass beads. Daily observations of biofilm thic kness, influent and effluent glucose substrate concentration, and effl uent dissolved and total organic carbon were made during the 13-day ex periment. Biofilm thickness appeared to reach quasi-steady-state condi tion after 10 days. A published biofilm process simulation program (AQ UASIM) was used to analyze experimental data. Comparison of observed a nd simulated variables revealed three distinct phases of biofilm accum ulation during the experiment: an initial phase, a growth phase, and a mature biofilm phase. Different combinations of biofilm and mass tran sport process variables were found to be important during each phase. Biofilm detachment was highly correlated with shear at the biofilm sur face during all three phases of development. (C) 1995 John Wiley & Son s, Inc.