Estimating the Biodegradation Kinetics by Mixed Culture Degrading Pyrene (Pyr)

Abstract

Biodegradation and kinetics of Pyrene (Pyr) degradation by a mixed culture previously isolated from hydrocarbon-polluted soil were conducted. Preliminary investigation on environmental factors affecting the degradation of Pyr such as temperature, pH and concentrations of Pyr was performed. These factors were optimised and established in aqueous experiments. In order to develop kinetics of Pyr degradation, an optimum temperature of 30oC and pH of 7.0 was used. Biodegradation kinetics was carried out, at first, using higher concentration between (100-700 ppm) as sole source of carbon in mineral salt medium (MSM) supplemented with 0.1% yeast extract. The result indicated that a range of concentration between (100-700 ppm) inhibits the performance of the mixed culture. A concentration range between (10-100 ppm) did not inhibit the growth of the mixed culture. A First-order rate constant, k was higher (0.0487 mg/lh) with a substrate concentration of 20 ppm than other concentrations. The average degradation rate constant is 0.0029 mg/Lh for all the concentrations tested. This indicated that the mixed culture could degrade over 0.0696 ppm of Pyr per day. It also confirmed that kinetics of microbial degradation was partially fitted into Monod model. The data can be used to estimate biodegradation of Pyr by a mixed culture and preliminarily estimation of degradation rates.