Degradation and Adsorption Behavior of Dibutyl Phthalate in Methanogenic Phase Refuse

The degradation and adsorption behavior of dibutyl phthalate (DBP) in methanogenic phase refuse was investigated through laboratory microcosm experiments. The results showed that the half-life of DBP in the sterilized refuse was 5.9 times higher than in unsterilized samples, but that it decreased by 35.8% when dominant bacterial strains were added. Different concentrations of DBP did not have obvious effects on its degradation. The half-lives of DBP were decreased by 53.0%, 37.2% and 20.8% when the refuse moisture increased from 20%, 40% and 60% to 80%, respectively. The pH of refuse was an important factor influencing DBP biodegradation, with the optimal pH being around 7.0. The optimal temperature for DBP degradation in refuse was around 30°C. In addition, the Freundlich model fits the adsorption and desorption isotherm of DBP for refuse with n values that suggest nonlinear adsorption characteristics. The free energy change ΔG value (−23.5 kJ mol) indicates that the adsorption of DBP on refuse was a physical reaction. Desorption hysteresis was observed in the DBP desorption experiments. Overall, the results indicate that DBP may accumulate in refuse, and that its transformation and bio-availability may be limited under landfill conditions.