Biofiltration performance and characteristics of high-temperature gaseous benzene, hexane and toluene

• The biodegradation preference was toluene > benzene > hexane.
• The removal rate and the CO2 production of the toluene biofilter were the highest.
• Toluene and benzene biofilters presented faster biomass accumulation.
• The toluene biofilter showed a higher mass distribution coefficient.
• The toluene biofilter showed a lower flooding velocity.

Three biofilters were developed to treat high-temperature (50 °C) gaseous benzene, hexane, and toluene. The performance of the biofilters was investigated; the parameters included removal efficiencies, kinetic analysis, biomass accumulation, pressure drops, and leachate TOC content. Results showed that the removal efficiency of toluene was the highest (more than 90%), followed by benzene (more than 70%) and hexane (more than 50%). The mass distribution coefficients (Km) of benzene, hexane, and toluene were 4.99, 3.50, and 6.36, respectively. And the yield coefficients (Y) were 0.91, 1.29, and 1.50 g dry biomass/g removed VOC for benzene, hexane, and toluene, respectively. A faster biomass accumulation resulted in lower flooding velocity of the biofilter treating toluene (210 m/h) than that of the biofilter treating hexane (257 m/h). The leachate from the biofilter treating toluene presented the highest TOC contents. Mass balance was similar among the three biofilters, suggesting that more than half of the removed VOCs were converted to CO2 and about 40% were converted to biomass.