The effect of granular sludge source on the anaerobic biodegradability of aromatic compounds

The ability of bacteria from five different granular sludge sources to anaerobically biodegrade aromatic compounds was evaluated. The biodegradabilities of phenol, 4-cresol, 2-aminobenzoate (2-AB) and 5-aminosalicylate (5-ASA) were determined by measuring compound conversion to methane in batch serum bottles at 30°C under agitated conditions over a period of at least 100 days. Phenol and 4-cresol were completely mineralized by all the granular sludges tested. This observation indicates a universal capacity of granular sludge to degrade phenol and 4-cresol; which would be expected since these compounds are intermediates in the anaerobic degradation of the commonly occurring amino acid tyrosine. In contrast, 5-ASA and 2-AB were degraded by only one or two granular sludges. Previous acclimation to an N-substituted aromatic was a prerequisite for 5-ASA degradation.