Degradation of the long-resistant pharmaceutical compounds carbamazepine and diatrizoate using mixed microbial culture

The microbial degradation of two recalcitrant pharmaceutical compounds, carbamazepine (CBZ) and diatrizoate (DTZ), was studied in laboratory batch experiments. We used a defined mixed microbial culture comprising four distinct microbial species that were previously known to have high decomposition capacity toward recalcitrant substances. Biological decomposition in liquid phase cultures for either CBZ or DTZ, or in a combination of the two, was conducted for 12 days. DTZ and CBZ were degraded by 43.2% and 60%, respectively from an initial concentration of 100 g L^-1. When degradation was assessed using a mixture of the two compounds, the initial degradation rates of CBZ and DTZ were lower than those observed in the single-compound study. However, the final cumulative removal efficiency was very similar. The extent of dissolved organic carbon (DOC) removal was correlated with the degradation of the pharmaceuticals.