Impact of water matrix on the removal of micropollutants by advanced oxidation technologies
journal contributionposted on 01.03.2019 by Ana R. Lado Ribeiro, Nuno F.F. Moreira, Gianluca Li-Puma, Adrian M.T. Silva
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Micropollutants (MPs) in the aquatic compartments are originated from many sources and particularly from the effluents of urban wastewater treatment plants (UWWTPs). Advanced oxidation technologies (AOTs) usually applied after biological processes, have recently emerged as effective tertiary treatments for the removal of MPs, but the oxidation rates of the single compounds may be largely affected by the constituent species of the water matrix. These species include dissolved organic matter and inorganic species (e.g., carbonate, bicarbonate, nitrite, sulphate, chloride). This review analyses the impact of such substances on common AOTs including photolysis, UV/H2O2, Fenton, photocatalysis, and ozone-based processes. The degradation efficiency of single MPs by AOTs results from the combined impact of the water matrix constituents, which can have neutral, inhibiting or promoting effect, depending on the process and the mechanism by which these water components react. Organic species can be either inhibitors (by light attenuation; scavenging effects; or adsorption to catalyst) or promoters (by originating reactive oxygen species (ROS) which enhance indirect photolysis; or by regenerating the catalyst). Inorganic species can also be either inhibitors (by scavenging effects; formation of radicals less active than hydroxyl radicals; iron complexation; adsorption to catalyst or decrease of its effective surface area) or promoters (e.g., nitrate ions by formation of ROS; iron ions as additional source of catalyst). The available data reviewed here is limited and the role and mechanisms of individual water components are still not completely understood. Further studies are needed to elucidate the wide spectrum of reactions occurring in complex wastewaters and to increase the adoption of AOTs in UWWTPs.
This work was financially supported by Projects: POCI-01-0145-FEDER-006984 – Associate Laboratory LSRE-LCM funded by European Regional Development Fund (ERDF) through COMPETE2020-Programa Operacional Competitividade e Internacionalização (POCI) – and by national funds through FCT – Fundação para a Ciência e a Tecnologia; Project POCI-01-0145-FEDER-030521 funded by ERDF funds through COMPETE2020 – POCI and by National Funds (PIDDAC) through FCT/MCTES; and Project NORTE-01-0145-FEDER-031049 funded by ERDF funds through NORTE 2020 and by national funds (PIDDAC) through FCT/MCTES. NFFM acknowledge the research grant from FCT (PD/BD/114318/2016), with financing from the European Social Fund and the Human Potential Operational Programme. The authors would like to acknowledge the financial support provided by COST-European Cooperation in Science and Technology, to the COST Action ES1403: New and emerging challenges and opportunities in wastewater reuse (NEREUS).
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