Occurrence and removal of selected pharmaceuticals and personal care products in three wastewater-treatment plants.

Residues of pharmaceuticals and personal care products (PPCPs) have been detected in surface waters. Incomplete removal of these compounds by wastewater-treatment plants (WWTPs) results in their presence in effluents and finally in surface waters. The occurrence and removal of four PPCPs was investigated in three WWTPs in Mississippi, USA, during a period of 1 year. Influent and effluent were sampled from the three WWTPs. Upstream and downstream samples of the WWTPs were also collected. All four PPCPs were detected in all influents where sulfamethoxazole showed the highest concentration levels with a median concentration of 1,640 ng/L, and carbamazepine was detected at the lowest level with a median concentration of 132 ng/L. Different PPCPs were removed to different extents varying from 99 to 100 %. Gemfibrozil showed the highest removal rates (73-100 %), whereas carbamazepine showed the lowest (-99 to -30 %). Secondary activated sludge in oxidation-ditch process showed remarkable PPCP-specific removal rates. Galaxolide was removed more than the other PPCPs, and sulfamethoxazole showed the least removal. Galaxolide was found to be a predominant PPCP in effluent among the PPCPs studied, and it was detected in all downstream (14.1-428.2 ng/L) and upstream (4.1-60.0 ng/L) samples. Sulfamethoxazole was removed more during the summer than the winter season. A clear increase of PPCP concentrations was observed in most downstream samples compared with upstream samples suggesting that discharges from WWTPs are the major source of PPCPs in surface waters.