Occurrence and removal of pharmaceuticals, caffeine and DEET in wastewater treatment plants of Beijing, China

The occurrence and removal of 13 pharmaceuticals and 2 consumer products, including antibiotic, antilipidemic, anti-inflammatory, anti-hypertensive, anticonvulsant, stimulant, insect repellent and antipsychotic, were investigated in four wastewater treatment plants (WWTPs) of Beijing, China. The compounds were extracted from wastewater samples by solid-phase extraction (SPE) and analyzed by ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC–MS/MS). Most of the target compounds were detected, with the concentrations of 4.4 ng L−1–6.6 μg L−1 and 2.2–320 ng L−1 in the influents and secondary effluents, respectively. These concentrations were consistent with their consumptions in China, and much lower than those reported in the USA and Europe. Most compounds were hardly removed in the primary treatment, while their removal rates ranging from −12% to 100% were achieved during the secondary treatment. In the tertiary treatment, different processes showed discrepant performances. The target compounds could not be eliminated by sand filtration, but the ozonation and microfiltration/reverse osmosis (MF/RO) processes employed in two WWTPs were very effective to remove them, showing their main contributions to the removal of such micro-pollutants in wastewater treatment.