Metabolic activity test in investigation of biodegradation in biological filters

The esterase activity (EA) metabolic activity test was shown to be applicable to measurement of the activity of biomass of biofilters. The method was reproducible and detected significant differences in biomass activity in different filters and at various depths within each filter. The highest biomass activity occurred at the bed surface in 60% of filter media. The EA test also revealed the changes of biomass activity during the time of filter operation as a result of backwashing. For all investigated filters maximum biomass activity in the middle of washing cycle was observed. Following backwashing, the activity dropped to a minimum. The relation between TOC (total organic carbon) and COD (chemical oxygen demand) removal and biomass activity were noted. The results presented in the paper suggest that the metabolic activity test can be used in investigation of the performance of biofilters.