Optimization of a combined system of vertical flow constructed wetland and solar photo-Fenton for ketoprofen removal in sewage and landfill leachate

Emerging contaminants in the environment are a matter of concern due to their widespread use and continuous disposal without proper treatment. Conventional treatments in sewage treatment plants (STPs) are not able to completely eliminate them, resulting in the presence of these compounds in several environmental matrices. Therefore, exploring and adding technologies to reduce or avoid the disposal of these compounds in the environment is necessary. This study aimed to use the solar photo-Fenton process combined with a partially saturated bottom vertical flow constructed wetland (VFCW) to remove ketoprofen (KET) from anaerobic effluent (sewage + landfill leachate) post-treated by a real-scale upflow anaerobic sludge blanket (UASB) reactor. The combined constructed wetland + solar photo-Fenton in pH 3.0 (CW + SPF3) and constructed wetland + solar photo-Fenton in pH 6.0 (CW + SPF6) systems showed high efficiency in degrading KET, achieving removal rates of 97% and 95%, respectively. The systems also showed efficiency in removing conventional parameters such as COD, BOD5,20, and turbidity. In addition to having a lower cost, only the combined CW + SPF6 system was able to eliminate toxicity for Artemia sp. and Lactuca sativa (TU < 0.4). The solar photo-Fenton process and constructed wetlands have proven to be compatible technologies. This combination resulted in an innovative and effective method for wastewater treatment systems containing emerging contaminants. The use of new technological arrangements for the treatment of sewage and effluents, such as constructed wetlands (CWs), which are nature-based solutions, and environmentally sustainable advanced solar oxidation processes, establish a NEXUS concept, promoting the circular economy.