Comparison of UV photolysis, nanofiltration, and their combination to remove hormones from a drinking water source and reduce endocrine disrupting activity.

A sequential water treatment combining low pressure ultraviolet direct photolysis with nanofiltration was evaluated to remove hormones from water, reduce endocrine disrupting activity, and overcome the drawbacks associated with the individual processes (production of a nanofiltration-concentrated retentate and formation of toxic by-products). 17β-Estradiol, 17α-ethinylestradiol, estrone, estriol, and progesterone were spiked into a real water sample collected after the sedimentation process of a drinking water treatment plant. Even though the nanofiltration process alone showed similar results to the combined treatment in terms of the water quality produced, the combined treatment offered advantage in terms of the load of the retentate and decrease in the endocrine-disrupting activity of the samples. Moreover, the photolysis by-products produced, with higher endocrine disrupting activity than the parent compounds, were effectively retained by the membrane. The combination of direct LP/UV photolysis with nanofiltration is promising for a drinking water utility that needs to cope with sudden punctual discharges or deterioration of the water quality and wants to decrease the levels of chemicals in the nanofiltration retentate.