Polyurethane foam medium for biofiltration. II: Operation and performance

A polyurethane foam medium with characteristics described in Part I of this paper was tested in a toluene degrading biofilter to demonstrate its abili ty to support an active biofilm and to study feasibility of a novel nutrien t addition and biomass wasting strategy. A laboratory-scale biofilter was f ed a model waste stream containing toluene for more than 300 days using emp ty bed residence times ranging from 1 to 4 min and toluene concentrations r anging from 50 to 200 parts per million by volume. Results reported herein demonstrate that a polyurethane foam medium with high porosity, suitable po re size, low density, and an ability to sorb water was able to remove over 99% of the influent toluene after implementation of a nutrient addition and biomass removal strategy. The strategy, made possible by use of the foam m edium, overcame problems such as clogging, high head loss, moisture content control, and nutrient limitation that are often associated with convention al biofilter operation.