BACKGROUND: The impact of inoculation on performance and subsequent community structure is a critical question in gas biofiltration processes. Thus, the aim of this study is to evaluate the impact of inoculation on biofilters packed with an inorganic medium and fed with a gaseous mixture (oxygenated and sulphur compounds).

BACKGROUND: Different physical and biological parameters are involved in the successful running of gas biofilters. The nature of the packing material has a great impact on service life of the biofilter, removal performances, microbial growth and operational costs. The aim of this study is then to gain insight to the influence of key physicochemical (pH) and hydrodynamic (mean residence time) specifications of three packing materials (lava rock, residuals of waste treatment and coco fibres) on both elimination efficiency of gaseous contaminants (dimethylsulfide, 3-methyl-butyraldehyde and methyl isobutyl ketone) and structure of the total bacterial community within non-inoculated and seeded biofilters. RESULTS: At steady-state, both material characteristics have no impact on biodegradation activity profiles as non-inoculated biofilters exhibited the same stratification pattern of elimination capacity, with better and faster elimination of oxygenated compounds compared with dimethylsulfide. Nevertheless, pH and mean residence time seem to influence the elimination capacity of the biofilters as alkaline pH value improved contaminants removal and higher abatement values are observed forbiofilters packed with a granular material. Moreover, both characteristics would induce the establishment of a specific structure of the total microbial community for each material.CONCLUSION: This study did not aim to provide a single general protocol for optimal packing material choice, but presented a systemic guideline to compare materials characteristics (pH, hydrodynamic parameters, shape), assessing their impact on biofilter performances, filter bed depth required for pollutants biodegradation and microbial community organization.