Microbial degradation of phenol in denitrifying conditions

The biodegradation of phenpol in anaerobic conditions by mixed population of bacteria in batch cultures or continuous cultures in packed bed reactor in medium with phenol as sole carbon source was effective. Phenol in concentrations up to 500 mg/l was degraded by bacteria in batch cultures (incubation temperature 30 degrees C) with increasing maximal rate without lag phase and at higher concentrations (up to 1000 mg/l) the activity of the bacteria was preceded by a lag phase lasting from 9 to 15 days. Phenol was degraded in continuous cultures with maximum efficiency (about 2500 mg/l x day) in the following conditions: incubation temperature 30 degrees C, phenol concentration in the medium of 200 mg/l and retention time of about 2 hours. Lowering of the temperature of the culture to 13 degrees C and 20 degrees C resulted in 10 and 5-fold decrease in the efficiency of the process, expressed as mg/l X day, respectively. Analysis of the composition of the bacteria among the facultatively growing Gram-negative rods showed that the incubation temperature visibly affected the species composition and domination pattern of denitrifying bacteria although their percent participation remained the same.