Ethylbenzene,o-Xylene, and BTEX Removal bySphingomonas sp. D3K1 in Rock Wool-Compost Biofilters

Abstract

Previously isolated Sphingomonas sp. D3K1 was biofilter (BF) inoculated into composite rock wool-compost packing media and biofiltration of single gas-ethylbenzene in BF1 and o-xylene in BF2-and mixed BTEX compounds in BF3 were investigated. At 62 s EBRT and feed flow rate of 0.14 m 3 /h, high removal efficiencies of 92.0 Ϯ 2.8%, 92.0 Ϯ 3.1%, and 89.2 Ϯ 1.1% were achieved in BF1, BF2, and BF3, respectively. Decreasing the EBRT to 48 s resulted in lower elimination capacities of the three biofilters, while regular nutrient addition showed an increase in the attainable elimination capacities for ethylbenzene and o-xylene of BF1 and BF2, respectively. Maximum elimination capacities of 34.3 g-ethylbenzene/m 3 /h (BF1) and 38.6 g-o-xylene/m 3 /h (BF2) were obtained at 48 s EBRT. For BF3, the maximum elimination capacity was 32.9 g-BTEX/m 3 /h at 62 s EBRT. In the case of mixed BTEX biofilter, o-xylene showed the most significant decrease in the biodegradability when nutrient was insufficient in the system. Sphingomonas sp. D3K1 was more favorable to the removal of toluene when o-xylene was less than 10 g/m 3 /h, but shifted to benzene when the loading rate of o-xylene was higher than 10 g/m 3 /h.

Biofiltration for BTEX Removal

“…The effect was not due to nutrient limitation, as nutrients were added to the biofilter. Similar behavior was observed by other researchers (Álvarez-Hornos et al, 2008;Cho et al, 2009;Torkian et al, 2003;Vergara-Fernández et al, 2007;Yang et al, 2006). It is possible that excessive microbial growth negatively impacted biofilter performance due to clogging, thereby causing a reduction of the biofilm surface and nonuniform flow of waste gas through the biofilter.…”

“…Several studies have investigated the effect of gas composition on biofiltration of mixtures. The kinetic parameters of benzene, toluene, ethylbenzene, and xylene degradation are very similar (Abumaizar et al, 1998;Cho et al, 2009;García-Peña et al, 2008;Maliyekkal et al, 2004), so as a first approximation, the biofiltration of BTEX mixtures can be approximated as a single-compound process. To distinguish between individual compounds, a competitive degradation mechanism can be used to describe the process (e.g., Oh et al, 1994).…”

Novel aerobic benzene degrading microorganisms identified in three soils by stable isotope probing

“…Specifically, this organism classified with the family Sphingomonadaceae (genus unclassified Sphingomonadaceae), found within a Proteobacteria. Microorganisms within this family can degrade a wide variety of both natural and anthropogenic compounds, including PAHs, BTEX and various pesticides (Balkwill et al 1997;Cho et al 2009;Greene et al 2000;Mueller et al 1997;Shi et al 2001;Stolz 2009). However, previous studies have involved either isolations (with testing for degradation) or clone libraries (from a contaminated site or sample), therefore uncertainty remains as to whether these organisms are responsible for contaminant degradation in situ or in a mixed culture.…”

Substrate interactions during the biodegradation of BTEX and THF mixtures by Pseudomonas oleovorans DT4

“…Such phenomenon might be attributed to the high toxicity of o-xylene, which was considered as the least degradable compound among the three xylene isomers (Cho et al, 2009).…”