H 2S Abatement in a biotrickling filter using iron(III) foam media

Abstract

Airstreams polluted with H 2S at inlet loads ranging from 2.4 to 40.9 g H 2S m −3 h −1 were treated in a biotrickling reactor packed with hematite bearing, open pore foam units, at Empty Bed Residence Times (EBRT) ranging from 20 to 60 s over a period of 80 d, with almost complete removal of the pollutant from the startup of the system. The media had been seeded with sludge from a local water works facility, and removal efficiencies in excess of 80% were consistently observed along the operation of the reactor, with an average of 98%. Based on section performance, being a section one third of the bed length, observed elimination capacities (EC) reached up to 88.7 g H 2S m −3 h − 1 and 72.0 g H 2S m −3 h −1 at section EBRT of 10 and 7 s, respectively. The observed EC values compared much better than data reported on other packed bed reactors using biological iron oxidization to treat H 2S airstreams indirectly, and so did it when comparing the EC per unit of specific area in a similar study using polyurethane (PU) foams. Further, and unlike PU packed biofilters, no compaction occurred due to the iron foam rigidity, which translated in much better observed gas phase pressure drop as opposed to other conventional biofilters. Denaturing gel gradient electrophoresis was performed on the biomass collected in the packing after the biofilter service, and it was found that though a multi bacterial colony was seeded in the system via the sludge, the only surviving genus was the iron oxidizing Alicyclobacillus spp.