IngentaConnect Active compost biofiltration of toluene

Abstract:

Composting of leaves and alfalfa (i.e. active compost) was used for the biofiltration of toluene-contaminated air in a 6-L biofilter (initial bed height: 180 mm). During the thermophilic phase (45 to 55 °C), toluene biodegradation rates reached 110 g toluene.m^-3.h^-1 at an inlet concentration of about 5 g.m^-3 and a gas residence time of 90 seconds. The highest rates were obtained late in the thermophilic phase suggesting a microbial adaptation was occurring. Biodegradation rates decreased rapidly (50% in 48h) in the cooling stage. Under mesophilic conditions, the maximum biodegradation rates that could be obtained by increasing the inlet toluene concentration were near 89 g toluene.m^-3.h^-1 which is similar to that reported in the literature for mature compost biofilters. No volatile by-product was detected by gas chromatography. Mineralization of ^14C-toluene and benzene showed that they were completely degraded into CO_2 and H_2O under both thermophilic and mesophilic conditions. Bacteria isolated from late mesophilic stage had the capacity to degrade all BTEX compounds but were not able to transform chlorinated compounds. No organisms were isolated which could use toluene as their sole source of carbon and energy at 50 °C. Active compost biofiltration should be an excellent process for the treatment of gaseous BTEX by biofiltration. This is the first report of thermophilic biofiltration of toluene.

Keywords: BTEX; biofiltration; compost

Language: English

Document Type: Regular paper

Affiliations: 1: Nserc Industrial Chair in Site Bioremediation, BIOPRO Research Center, Department of Chemical Engineering, École Polytechnique de Montréal, Montreal QC, H3C 3A7, Canada

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