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 ability to support an active biofilm and to study feasibility of a novel nutrient addition and biomass wasting strategy. A laboratory-scale biofilter was fed a model waste stream containing toluene for more than 300 days using empty bed residence times ranging from 1 to 4 min and toluene concentrations ranging from 50 to 200 parts per million by volume. Results reported herein demonstrate that a polyurethane foam medium with high porosity, suitable pore 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 medium, overcame problems such as clogging, high head loss, moisture content control, and nutrient limitation that are often associated with conventional biofilter operation.