Biodegradation of phenol by unacclimated and phenol-acclimated activated sludge: Effects of operational factors on biodegradation efficiency and kinetics

This study was conducted to investigate the effects of operational factors, namely: 1. type of activated sludge; 2. activated sludge concentration; 3. initial phenol concentration; and 4. addition of sucrose; on the biodegradation of phenol in batch experiments. At various initial phenol concentrations, complete phenol biodegradations with chemical oxygen demand (COD) removal of 95% were achieved by both unacclimated and phenol-acclimated activated sludge. The performance of biodegradation was greatly enhanced, with biodegradation time shortened from 330-1260 to 35-330 min for initial phenol concentrations of 25-250 mg l-1, when the activated sludge was acclimated to the target compound, despite the low acclimation concentration of 50 mg l-1. Phenol biodegradation time was found to decrease with increasing activated sludge concentration and decreasing initial phenol concentration. In the presence of sucrose as co-substrate, biodegradations of phenol by both unacclimated and phenol-acclimated activated sludge were improved. The kinetic data for the biodegradation of phenol was well-fitted into pseudo-first-order model. The values of rate constant of phenol-acclimated activated sludge were found to be higher compared to those of unacclimated activated sludge under all the operational conditions studied. For phenol-acclimated activated sludge, the values of pseudo-first-order rate constant, k, were observed to decrease with increasing concentration of activated sludge and decreasing initial phenol concentration. © Penerbit Universiti Sains Malaysia, 2017.