Evaluation of pharmaceutical removal through a full-scale UASB-CW system in a water-scarce Mediterranean region

Abstract

In a world threatened by water scarcity, the use of non-conventional water sources, as reclaimed wastewater, for irrigation purposes is a promising option. Nonetheless, a suitable water treatment strategy must be implemented to reduce the concentration of emerging contaminants such as pharmaceutically active compounds (PhACs). Upflow anaerobic sludge blanket (UASB) technology is characterized by lower sludge production, lower energy demand as well as lower construction and operational costs compared with conventional activated sludge systems. In this work, the efficiency of a UASB system coupled to a constructed wetland (UASB-CW) was evaluated for the removal of pharmaceuticals present in urban wastewater on a Greek Island in a Mediterranean area suffering from water scarcity. Results showed that influent wastewater (IWW) concentrations in summer doubled in fall (238 856 ng L⁻¹ and 95 057 ng L⁻¹, respectively). The UASB reactor achieved a high removal efficiency for PhACs, particularly for acetaminophen (the most concentrated PhAC in the IWW), with removal rates of 88% in fall and 90% in summer, while exhibiting lower removal rates for other PhACs. The CW, however, decreased the concentration of most pharmaceuticals. The overall removal rate of the system ranged between 64% (summer) and 69% (fall) of the total IWW concentrations. Upon irrigation with reclaimed water, the impacts on the aquatic and terrestrial ecosystems were also considered. Effluent dilution and/or further polishing treatment would be necessary to better eliminate the contaminants and prevent any risk to the environment.