Optimisation of Pyrene Removal by a Mixed Culture in a Soil-Slurry Bioreactor using Response Surface Methodology (RSM)

Bioremediation of pyrene by a mixed culture enriched from hydrocarbon-polluted soil was performed in a soil-slurry bioreactor. A Munchong series, a Malaysian soil with the following properties: silty clay, organic carbon content of 4.7% and pH 7.22 was used. An experiment was designed using response surface methodology (RSM) with treatment combinations of soil-water ratio of (0.1-0.2 w/v), concentration of pyrene to soil ratio (500-1000mg/Kg) and different pH (5-8) combinations. The result shows that with higher ratio of pyrene concentration 1000mg/Kg of soil and minimum pH of 5 at the beginning produced highest percentage of pyrene removal from the bioreactor soil. The analysis of factors shows that biomass growth in the reactor depends only on contaminant concentration and initial pH and not soil/water ratio. This is a promising method for optimising ex-situ remediation of soil before scaling up and, with highly acclimatised mixed culture; significant concentration of pollutant will be removed.