DEGRADATION OF BTEX COMPOUNDS IN LIQUID-MEDIA AND IN PEAT BIOFILTERS

A mixed culture, enriched from Sphagnum peat moss, contaminated with g asoline vapours, degraded individual and mixed components of BTEX (ben zene, toluene, ethylbenzene, xylene), Complete degradation of radiolab elled toluene by the mixed culture was observed in mineralisation stud ies. Individual isolates from a mixed culture containing Pseudomonas m altophilia, P. testosteroni and P. putida biotype A exhibited contrast ing BTEX degradation patterns. While P, putida biotype A degraded all of the BTEX compounds, P. maltophilia and P. testosteroni appeared una ble to degrade benzene and xylenes, respectively, When the peat, inocu lated with the mixed culture, was used as a biofilter (6.2 cm diameter x 93 cm length) for degradation of toluene and ethylbenzene vapours, percentage removal efficiencies were 99 and 85, respectively. When the capacity of the biofilter to degrade a combination of BTEX compounds was evaluated, percentage removal efficiencies for toluene, ethylbenze ne, p-xylene, o-xylene and benzene were 99, 85, 82, 80 and 78, respect ively, The importance of using the mixed culture as an inoculum in the biofilter was established and also the relationship between contamina ted vapour flow rate and percentage removal efficiency.