Biofiltration of gasoline and diesel aliphatic hydrocarbons

Abstract

The ability of a biofilm to switch between the mixtures of mostly aromatic and aliphatic hydrocarbons was investigated to assess biofiltration efficiency and potential substrate interactions. A switch from gasoline, which consisted of both aliphatic and aromatic hydrocarbons, to a mixture of volatile diesel n-alkanes resulted in a significant increase in biofiltration efficiency, despite the lack of readily biodegradable aromatic hydrocarbons in the diesel mixture. This improved biofilter performance was shown to be the result of the presence of larger size (C 9 -C 12 ) linear alkanes in diesel, which turned out to be more degradable than their shorter-chain (C 6 -C 8 ) homologues in gasoline. The evidence obtained from both biofiltration-based and independent microbiological tests indicated that the rate was limited by biochemical reactions, with the inhibition of shorter chain alkane biodegradation by their larger size homologues as corroborated by a significant substrate specialization along the biofilter bed. These observations were explained by the lack of specific enzymes designed for the oxidation of short-chain alkanes as opposed to their longer carbon chain homologues.Implications: Biological removal of petroleum hydrocarbons from contaminated air has not become a widely used technology due to its low efficiency. This paper presents the analysis of this problem using bench-scale experiments and provides several reasons for the low biodegradation efficiency of gasoline. The results reported suggest that gasoline removal efficiency strongly depends on the substrate composition, with aromatic hydrocarbons being removed preferentially. The study also opens up a new perspective for the efficient biofiltration of diesel hydrocarbons as opposed to gasoline, as higher molecular weight n-alkanes of diesel were removed readily. By contrast, low-molecular-weight n-alkanes of gasoline turned out to be poor substrates for biofiltration, and the biological reasons for this phenomenon were suggested.

A two-stage combined trickle bed reactor/biofilter for treatment of styrene/acetone vapor mixtures

“…[1,2,6,36] Bacillus and Rhodococcus were also previously identified as efficient VOC degraders. [1,2,6,36] Due to the observed accumulation of acetone in the TBR circulating medium, extended tests of growth on acetone were carried out. Starting concentrations of 50, 100, 500, 1000 and 2000 mg.L ¡1 were used.…”

“…and the Enterobacteriaceae isolate exhibited the lowest biodegradation efficiency. Fusarium solani is known as an efficient degrader of a wide range of pollutants including aromatics and aliphatic hydrocarbons as well as oxygenated compounds, [6,34,35] similar to Pseudomonas genus. [1,2,6,36] Bacillus and Rhodococcus were also previously identified as efficient VOC degraders.…”

“…Fusarium solani is known as an efficient degrader of a wide range of pollutants including aromatics and aliphatic hydrocarbons as well as oxygenated compounds, [6,34,35] similar to Pseudomonas genus. [1,2,6,36] Bacillus and Rhodococcus were also previously identified as efficient VOC degraders. [1,2,6,36] Due to the observed accumulation of acetone in the TBR circulating medium, extended tests of growth on acetone were carried out.…”

“…This arrangement enabled the prevention of bed clogging while the use of a different packing material in the second stage, with a low voidage and high specific surface area, enabled enhanced cell attachment and mass transfer, so the remaining poorly degradable components were also removed with a high efficiency. [6] The aim of the current study was to evaluate the performance of two different reactor types in series, a TBR and BF, in treating a binary mixture of styrene and acetone vapors. As the opposite of styrene, acetone exhibits facile gas-liquid mass transfer.…”

“…Several possible combinations of biological reactors can be found in literature. Operational advantages may be obtained as a result of integrating two bioreactors, e.g., biofilter-biofilter, [6][7][8][9] TBR-biofilter(s), [10][11][12][13][14] biofilter-TBR, [15] mixing reactor-TBR, [16] and bioscrubber-biofilter. [17] In such integrated reactors, the expected TBR positioning is in front of BF, due to the high water usage in the TBR.…”