Freeze concentration for removal of pharmaceutically active compounds in water

A progressive freeze concentration process, unidirectional downward freezing (UDF), was investigated for removal of five commonly used pharmaceuticals (ibuprofen, gemfibrozil, acetylsalicylic acid, metoprolol and sulfamethoxazole) in water. The feed water with the pharmaceutically active compounds (PhACs) at concentrations from ng/L to mg/L range was frozen at −7 and −15 °C. The separation efficiency of PhACs in the single stage and two-stage UDF was examined. By freezing only 80% (volume) of the feed water and without washing of the ice, about 84–92% reduction of the drug content in ice was achieved in the single stage UDF and about 99% reduction in the two-stage UDF. The partitioning behavior of the PhACs in the ice and liquid phases seems different from the solutes in glucose solutions or liquid foods reported in the literature. A strong linear relationship between the PhACs concentration and their TOC concentration was established, suggesting that TOC, a parameter commonly used to measure WWTP effluent quality might be used to monitor the level of PhACs in WWTP effluent.