Ethinylestradiol removal of membrane bioreactor effluent by reverse osmosis and UV/H2O2: A technical and economic assessment

Synthetic hormone 17 alpha-ethinylestradiol (EE2) is not completely removed by conventional wastewater treatment plants and therefore is often detected in surface and groundwater, sludge and sediments. Due to its persistence in the environment and its estrogenic potential, a high removal of EE2 from wastewaters before its disposal has become a concern from an environmental point of view, particularly when considering urban reuse applications. This work investigated the application of advanced processes to treat synthetic municipal wastewater containing EE2 after treatment in a membrane bioreactor (MBR). Two advanced processes were assessed: the first is advanced oxidation process (AOP), using hydrogen peroxide (H2O2) and ultraviolet (UV) light (mute MBR-AOP) and the second, reverse osmosis (RO), in this case using UV/H2O2 to treat the retentate from RO (route MBR-RO). EE2 concentration in final effluent was one order of magnitude lower in mute MBR-AOP than in route MBR-RO. Implications for disposal or water reuse were discussed considering the importance of other water quality parameters as well. Economic estimates for CAPEX, OPEX and total cost were made. The introduction of the oxidative step (UV/H2O2) after MBR caused an increase in the total cost of US$ 0.39/m(3). In turn, mute MBR-RO increased the total process cost by US$ 0.86/m(3), showing that reduction of volume to be treated by UV/H2O2 in this route did not offset the cost associated with the acquisition and operation of RO. The total cost was estimated at US$ 2.47/m(3) for MBR-AOP and US$ 2.94/m(3) for MBR-RO for a design flow of 10 m(3)/h.

Automated summary

Synthetic hormone 17 alpha-ethinylestradiol (EE2) is difficult to remove completely in wastewater, advanced processes can reduce its concentration, but at the cost of increased total cost.