Thermophilic waste air treatment of n‐alkanes in a two‐phase bubble column reactor: the effect of silicone oil addition

Abstract

AbstractBACKGROUNDThermophilic waste air biofiltration was developed to overcome the often observed drop in pollutant removal efficiency caused by classical reactor overheating above the mesophilic temperature range. To date, only a few studies have been reported on thermophilic biofiltration of airborne hydrophobic pollutants. In this work, a bubble column reactor (BCR) operated at 50 °C was used to treat waste air contaminated by a mixture of gasoline/kerosene range n‐alkanes with a microbial consortium acquired from burning coal dumps.RESULTSSeveral strategies were used to increase the low pollutant removal efficiency initially observed. Of these, only the addition of NAP (silicone oil) to the reactor led to increased removal efficiency, due to formation of water‐in‐oil emulsion. Analysis of the microbial consortium revealed bacteria from the Paenibacilaceae family (FN667384) and unidentified thermophilic fungi (HQ693517.1) to be the dominant organisms within the analyzed category, with 48% and 99% abundance, respectively. In the presence of NAP, longer‐chain n‐alkanes (C10–C12) were degraded efficiently, unlike their shorter‐chain homologs. After 7–10 days, the degradation of shorter‐chain C7–C8 n‐alkanes was observed at the expense of their longer‐chain homologs.CONCLUSIONA two‐phase thermophilic BCR proved successful in treating an airborne n‐alkane mixture. With the NAP addition, the apparent mass transfer limitations were overcome, creating a suitable environment for thermophilic hydrocarbon biodegradation. As a result, efficient degradation of longer‐chain n‐alkanes was enabled upon emulsification, whereas the removal of shorter‐chain C7–C8 hydrocarbons occurred later, most likely as a consequence of the biomass adaptation. © 2021 Society of Chemical Industry