Anaerobic biodegradability of alkylbenzenes and phenol by landfill derived microorganisms

Abstract

The objectives of this research were to evaluate the anaerobic biodegradability of benzene, toluene, ethylbenzene, xylenes, phenol and p-cresol by microorganisms present in decomposing refuse and to study the effects of environmental conditions, pertinent to landfills, on the anaerobic degradation of phenol and p-cresol by refuse derived microbial consortia. Microbial inocula were derived from refuse from both landfills and laboratory reactors. While toluene biodegradation was only measured with one inoculum, broad degradation for phenol and p-cresol was measured. Cultures enriched on refuse were then derived from two samples to evaluate conservation of degradative activity against phenol. In one enrichment, phenol degrading activity was maintained after 6 months, while this activity decreased in a second culture. Phenol and p-cresol enrichment cultures also exhibited activity against other hydroxyl-substituted aromatics but not mono-chlorinated phenols. Cellulosic carbon and soluble trace constituents extracted from fresh refuse stimulated phenol degradation with one enrichment. However, the cellulosic carbon was inhibitory to the other phenol and p-cresol enrichment cultures. The pH optima for all cultures were between 6.5 and 7.0. Finally, a high concentration of acetate prevented the efficient removal of benzoate and consequently inhibited phenol degradation. Landfills were shown to be a habitat harboring anaerobic microbial populations capable of degrading toluene and hydroxyl-substituted aromatics, suggesting that contaminant degradation may be maximized with proper landfill management.