| Abstract: | ABSTRACT Trickle-bed air biofilters (TBABs) are suitable for treatment of hydrophilic volatile organic compounds, but they pose a challenge for hydrophobic compounds. Three laboratory-scale TBABs were used for the treatment of an airstream contaminated with different ratios of n-hexane and benzene mixtures. The ratios studied were 1:1, 2:1, and 1:3 n-hexane:benzene by volume. Each TBAB was operated at a pH of 4 and a temperature of 20 °C. The use of acidic-buffered nutrient solution was targeted for changing the microorganism consortium to fungi as the main biodegradation element. The experimental plan was designed to investigate the long-term performance of the TBABs with an emphasis on different mixture loading rates, removal efficiency with TBAB depth, volatile suspended solids, and carbon mass balance closure. n-Hexane loading rate was kept constant in the TBABs for comparison reasons and ranged from 4 to 22 g/(m3.hr). Corresponding benzene loadings ranged from 4 to 43 g/(m3.hr). Generally, benzene behavior in the TBAB was superior to that of n-hexane because of its higher solubility. n-Hexane showed improved performance in the 2:1 mixing ratio as compared with the other two ratios. IMPLICATIONS The use of biofilters is a cheap and attractive option; however, their application is limited because of several challenges. One of them is the reluctance of hydrophobic compounds for biodegradation and the coexistence of other compounds in air emissions. This paper evaluated the impact of different mixing ratios of two hydrophobic compounds and the effect of increasing influent concentration. Finally, a comparison is provided on the best performance attained for these hydrophobic compounds as single solutes. The results of this study will aid in the design and operation of full-scale biofilters. |
