Interactive effects of dual short-chain n-alkanes on removal performances and microbial responses of biotrickling filters

Enhanced biotrickling filtration at the presence of surfactants could be competitive in treatment of waste gas streams polluted by hydrophobic volatile organic compounds (VOCs) such as light hydrocarbons, while few such reports are available. Herein, biotrickling filters (BTFs) were applied to investigate the removal performances for binary-component n-alkanes (n ≤ 6) at the presence of sodium dodecyl benzene sulfonate (SDBS), and the microbial responses were also examined. Interestingly, results showed that the existence of shorter chain n-alkanes promoted the removal of longer chain n-alkanes, as the elimination capacities (EC) of BTF for n-hexane increased by 44 ± 1.2 % when there was methane in incoming gas stream. While the presence of longer chain n-alkanes antagonistically affected shorter chain n-alkane removal, as EC for methane decreased by 65 ± 8.1 % at the presence of n-hexane. Additionally, the presence of SDBS improved the mixed n-alkane removal. EC of the BTF with 15 mg/L SDBS for mixed propane and n-hexane reached 55 ± 1.4 and 31 ± 0.5 g/m3·h respectively, which increased by 90 ± 4.6 % and 47 ± 0.9 % compared with those without SDBS. The richness of Bacillus and Sporosarcina was improved in the BTF fed with SDBS. Moreover, the presence of SDBS improved the content of hydrophobic proteins and the activity of fluorescent substances in extracellular polymeric substances. Also, both the activities of ATPase and the antioxidant capacity of microbial cells exhibited higher than that when SDBS was not added. These data could lead to a better understanding and more reasonable design of biotrickling filtration to remove n-alkanes from waste gas streams of refinery wastewater treatment plants.