Removal of benzene and toluene from a refinery waste air stream by water sorption and biotrickling filtration

Abstract

The paper presents the results of an analysis of a two-stage pilot plant for the removal of toluene and benzene from the exhaust air of an industrial wastewater treatment plant (WWTP). The two-stage air process combines a water scrubber and a biotrickling filter (BTF) in sequence, and treats air stripped from the liquid phase compartments of the WWTP. During the experimental period, the pilot plant treated an airflow of 600 Nm 3 h -1 . Average concentrations of the waste air stream entering the water scrubber were 10.61 mg Nm -3 benzene and 9.26 mg Nm -3 toluene. The water scrubber obtained medium-high removal efficiencies (averages 51% and 60%, for benzene and toluene, respectively). Subsequent passage through the BTF allowed a further reduction of average concentrations, which decreased to 2.10 mg Nm -3 benzene and to 0.84 mg Nm -3 toluene, thereby allowing overall average removal efficiencies (REs) of 80% and 91% for benzene and toluene, respectively. Results prove the benefits obtained from a combination of different removal technologies: water scrubbers to remove peak concentrations and soluble compounds, and BTFs to remove compounds with lower solubility, due to the biodegradation performed by microorganisms.

Removal of odorous sulphur compounds from industrial gases by biotrickling filters

“…These advantages are their limited size, longer life, lower pressure drop with subsequent lower power consumption, easy control of temperature, pH, salt concentration and metabolite accumulation, wide range of treatable pollutants, greater stability of operation and better atmospheric dilution of the plume (Xue et al, 2013). BTFs have been widely tested and applied in the treatment of exhaust air pollutants from pharmaceutical (Chen et al, 2006), paint (Mathur and Majumder, 2008), refinery (Viotti et al, 2015) and livestock industries (van Groenestijn and Kraakman, 2005), as well as wastewater (Lebrero et al, 2014) and solid waste treatment facilities (Gutierrez et al, 2014). BTFs are reactors partly filled with inert materials, such as lava rock, shells, and plastic spheres or rings, which serve as a physical support for the growth of biomass.…”