Elimination of β-blockers in sewage treatment plants

β-Blockers are used to treat high blood pressure as well as patients recovering from heart attacks. In several studies, they were detected in surface water, thus indicating incomplete degradability of these substances in sewage treatment plants (STPs). In this study, we determined the sorption coefficients (KD) and degradation rates of the four β-blockers sotalol, atenolol, metoprolol and propranolol in sludge from an STP operating with municipal wastewater. The sorption coefficients (KD, standard deviations in brackets) were determined as 0.04(±0.035), 0.04(±0.033), 0.00(±0.023) and 0.32(±0.058) L g−1COD, and the pseudo-first-order degradation rate constants were estimated to be 0.29(±0.02), 0.69(±0.05), 0.58(±0.05) and 0.39(±0.07) L d−1 g−1COD for sotalol, atenolol, metoprolol and propranolol, respectively. These values translate into a typical elimination in STPs (sludge concentrations of 4 gCOD L−1 and a hydraulic retention time of 6 h) of 25%, 37%, 44% and 50% for sotalol, propranolol, metoprolol and atenolol, respectively. These results are also confirmed by measurements in two municipal STPs for atenolol, sotalol and propranolol. The estimated eliminations are slightly too high for metoprolol.