Performance promotion and its mechanism for n-hexane removal in a lab-scale biotrickling filter with reticular polyurethane sponge under intermittent spraying mode

Abstract

Mass transfer limitations commonly challenge biofiltration for n-hexane emissions due to its high hydrophobicity. In this study, a bench-scale biotrickling filter (BTF) packed with reticulated polyurethane sponge was evaluated for n-hexane removal at various organic loading rates (OLRs) (ranging from 15 to 60 g m−3 h-1) and gas empty bed contact times (EBCTs) (ranging from 30 to 7.5 s). The obtained results show that the designed BTF can effectively remove n-hexane under intermittent spraying mode of the nutrient solution and the reticulated configuration of the packing media, which resulted in the spatial development of mycelium and enhanced mass transfer of n-hexane. The mean maximum removal efficiencies (REs) of n-hexane were 92.6 ± 0.9 %, 86.7 ± 4.8 %, and 63.8 ± 3.3 % under the OLRs of 15.67, 30.20, and 61.59 g m−3 h-1, respectively. When the BTF was operated under gas EBCTs of 30, 15, and 7.5 s, average REs of 85.9 ± 5.7 %, 44.8 ± 6.3 %, and 31.2 ± 2.5 % were achieved. The BTF also showed a superior fluctuation resistance capability and prevented excessive biofilm accumulation due to the reticular configuration of the polyurethane sponge. Results present in this study could provide an alternative consideration for the practical industrial application in treating hydrophobic VOC like n-hexane.