Enhanced biodegradation of n-hexane from the air stream using rhamnolipidin a biofilter packed with a mixture of compost, scoria, sugar beet pulp andpoplar tree skin

Özet

Biofiltration of n-hexane vapors with and without using rhamnolipid biosurfactant was investigated on a la-boratory scale biofilter packed with compost, scoria, sugar beet pulp, and poplar tree skin at empty bed residencetimes (EBRT) of 30, 60 and 120s for a period of 131 days. Acclimation of microorganism in the biofilter wasachieved in 31 days with an average n-hexane concentration of 0.269 gm−3and EBRTs of 120s. The resultsdemonstrated that average removal efficiencies (RE) for the corresponding EBRT with n-hexane loading rates(IL) of 6.7–137 gm−3h−1were 18.7 ± 1.67%, 28.9 ± 4.06% and 46.8 ± 8.2% without biosurfactant. While,the average REs in presence of the biosurfactant were 23.98 ± 4.08%, 42.4 ± 9.7% and 85.13 ± 10.44% atEBRTs of 30, 60 and 120s, respectively. About 53% of n-hexane removal was related to the segment 1 of thebiofilter, where the bacterial and fungi population of its biofilm was 2 × 1015and 1.3 × 109CFU g−1(dryweight), respectively, which was significantly more than the other segments. For all the tested inlet con-centrations, the RE was significantly increased by increasing EBRT and decreasing IL of n-hexane. The results ofthis study confirm the efficiency enhancement of rhamnolipid in biofiltration of hydrophobic compounds such asn-hexane from air streams.