Evaluation of innovative packing materials for the biodegradation of H2S: a comparative study
Résumé
The biofiltration of gas polluted with H2S was carried out using innovative configurations of packing materials (i.e. a new synthetic material called UP20, sapwood, peat, pozzolan and pine bark). A comparison of seven different configurations (media alone or in combination) was made based on biofilter performances and pressure drop measurements. Biofilters were operated continuously for at least 95 days at a constant flow rate (0.5 N m(3) h(-1) corresponding to a superficial velocity of 65 m h(-1) and an empty bed residence time of 57 s). Elimination capacities and removal efficiencies were calculated according to loading rates varying from 0 to 25.59 m(-3) h(-1) (inlet concentration up to 400 mg m(-3)). Biofilter performances were modelled and biokinetic constants were calculated using the Ottengraf model and a modified Michaelis-Menten model. In terms of elimination capacity, packing materials can be ordered from the most efficient to the least efficient: peat-UP20 in a mixture > peat-UP20 in two layers > peat > pozzolan-UP20 in two layers > pine bark > sapwood-UP20 in two layers > sapwood. A maximal removal rate, V-m, of 55 g m(-3) h(-1) was calculated for biofilters filled with peat-UP20 (in a mixture or in two layers) and peat (in comparison, V-m = 8.3 m(-3) h(-1) for a biofilter filled with sapwood). Peat is the best material to treat high H2S concentrations and the addition of UP20 can significantly increase the removal efficiency. The pozzolan-UP20 combination represents an interesting packing material to treat pollutant loading rates up to 5 g m(-3) h(-1) with low pressure drops. For low H2S concentrations, sapwood can be considered as a good support for H2S degradation with pollutant loading rates up to 4 g m(-3) h(-1). (C) 2010 Society of Chemical Industry