Phenol Removal from Synthetic Wastewater by Alcaligenes Faecalis: Online Monitoring

Phenol, a compound regarded as a priority pollutant by the USA environmental protection agency, is a toxic contaminant in wastewaters and industrial effluents. Biodegradation of phenol have been extensively investigated using pure or mixed cultures in different kind of bioreactors. In this work, biological removal of phenol by Alcaligenes faecalis has been studied. For petrochemical industry, even at low concentrations (400 mg/L), phenolic compounds can inhibit microbial growth. Therefore the experiments have been conducted at different initial concentrations from 400 to 1000 mg/L. In this range the bacterium could utilize phenol in 22 to 100 hours. The Alcaligenes faecalis growth rate and substrate degradation rate were only limited by substrate concentration at fixed temperature, initial pH and aeration rate. The metabolic pathway for the phenol degradation occurs via catechol derivates, before ortho oxidation ring cleavage. The ortho oxidation chain contains many stages with different acidity, so pH and DO changes have been monitored. pH increases to more than 7.16 and then decreases to about 5. There was a logical relation between changes in pH, DO, cell growth rate and phenol degradation rate. The results of this study can help to control phenol biodegradation more effectively.