abstract background: biogas is obtained by anaerobic decomposition of organic wastes buried materials used to produce electricity, heat and biofuels. biogas is at the second place for power generation after hydropower and in 2000 about 6% of the world power generation was allocated to biogas. biogas is composed of 40–45 vol% co2, 55–65 vol% ch4, and about 1% non-methanevocs, and non-methane vol...

Urinary biomarkers of exposure are used widely in biomonitoring studies. The commonly used urinary biomarkers for the aromatic solvents toluene (T), ethylbenzene (E), and m-xylene (X) are o-cresol, mandelic acid, and m-methylhippuric acid. The toxicokinetics of these biomarkers following inhalation exposure have yet to be described by physiologically based pharmacokinetic (PBPK) modeling. Five ...

BTEX (benzene, toluene, ethylbenzene and xylene) concentrations, factors affecting their levels, and the exposure risks related to these compounds were studied in waterpipe (Ghalyun/Hookah) cafés of Ardabil city in Islamic Republic of Iran. 81 waterpipe cafés from different districts of Ardabil city were selected and their ambient air was monitored for BTEX compounds. Air samples were taken fro...

The primary objective of this study was to evaluate the impact of substrate interactions on the biotransformation rates and mineralization potentials of gasoline monoaromatics and methyl tert-butyl ether (MTBE), compounds that commonly co-exist in groundwater contaminant plumes. A mixed culture was derived from gasoline-contaminated aquifer material using toluene as the enrichment substrate. Tw...

Polybrominated diphenyl ethers (PBDEs) are a class of flame retardants that have been widely used in consumer products, but that are problematic because of their environmental persistence and endocrine-disrupting properties. To date, very little is known about PBDE degradation by aerobic microorganisms and the enzymes involved in PBDE transformation. Resting cells of the polychlorinated bipheny...

Benzene, toluene, ethylbenzene, o-, m-, and p-xylenes (BTEX), and polycyclic aromatic hydrocarbons (PAHs) were extracted from eight manufactured gas plant (MGP) soils from sites that had been abandoned for several decades. Supercritical fluid extraction (SFE) with pure carbon dioxide demonstrated the presence of BTEX compounds that were highly sequestered in both coal gas and oil gas MGP soils ...

A biofilter was used to treat air polluted with ethylbenzene. Macadamia nutshells, which are a cheap waste product in Thailand, were chosen as the packing material for the biofilter. The moisture content (6.6 w%), water holding capacity (16.8 w%), nutshell density (1.3 g ml) and organic content (78.0 w%) of the macadamia nutshell were measured. The biofilter was operated during 5 months, in whi...

Elevated concentrations of sulfide in groundwater (approximately 63 mg S(2-)/L in water and 500 mg dissolved H2S/L dissipating from the wellhead) at a field site near South Lovedale (OK, USA) were inhibiting the activity of sulfate-reducing bacteria (SRB) that are known to degrade contaminants, including benzene, toluene, ethylbenzene, and xylenes. Elevated concentrations of these contaminants,...