Impact of interchanging VOCs on the performance of trickle bed air biofilter

Trickle bed air biofilters (TBABs) were evaluated under conditions of an interchange of the feed volatile organic compounds (VOCs). Two aromatic compounds (toluene and styrene) and two oxygenated compounds (methyl ethyl ketone and methyl isobutyl ketone) were interchanged as single solutes. The results obtained revealed that the biofilter provided high removal efficiency within the critical loading, which was previously defined in the non-interchanging VOC-fed biofilters. The biofilter recovered easily to the 99% removal after interchanging to oxygenated compounds, regardless of the immediately preceding compound fed to each biofilter, but for aromatic compounds, a longer reacclimation period was required. The biofilter response after interchange of feed VOCs depended on the physicochemical property of feed VOCs as well as the biomass retained in the biofilter prior to interchanging VOC. Using high EBRT at the critical loading (which corresponds to high inlet concentration), problems related to oxygen limitation within the biofilm may have appeared. It was noticed that a smaller ratio of COD/N and a larger ratio of CO2/COD were encountered after an interchange of the feed VOCs.