However, once the adsorption capacity was saturated, the treatment efficiency dropped dramatically. Later, biological activity increased to the point where effective treatment was possible. The main obstacle to effective treatment was the slow growth of biomass in the lower portions of the column. The average and maximum elimination capacities of the biofilter were high compared to published bench scale results for compost biofilters. Elimination rates were proportional to pollutant loading.
Plate counts show that both bacterial and fungal numbers increased as the column operated.