Contaminants of Emerging Concern Removal by High-Energy Oxidation-Reduction Processes: State of the Art

Abstract

The presence of ‘emerging contaminants’, i.e., chemicals yet without a regulatory status and poorly understood impact on human health and environment, in wastewater and aquatic environments is widely reported. No established technology, to date, can simultaneously and completely remove all these contaminants, even though some Advanced Oxidation Processes (AOPs,) have demonstrated capacity for some degradation of these compounds. High-energy, radiolytic processing of water matrices using various sources: electron beam (EB), ɣ-rays or non-thermal plasma (NTP) have shown excellent results in many applications, although these remain at the moment isolated examples and scarcely known. High-energy irradiation constitutes an additive-free process that uses short-lived, highly reactive radicals (both oxidating and reducing) generated by water radiolysis, which can instantaneously decompose organic pollutants. Several studies have demonstrated its effectiveness, as a stand-alone process or combined with others, in the rapid decomposition (up to complete mineralization) of organic compounds in pure and complex solutions, and in the removal or inactivation of microorganisms and parasites, without production of leftover residual compounds in solution. High-energy oxidation processes (a.k.a. Advanced Oxidation & Reduction Processes—AORPs) could have a primary role in future strategies addressing emerging contaminants.

Semiconductor Electrode Materials Applied in Photoelectrocatalytic Wastewater Treatment—an Overview

“…Table 1. Comparison of standard potentials determined for some oxidants and radical species [47][48][49]. In the case of electrochemical degradation, it is important to select suitable electrode material, which should be not only stable enough during the process, but should also guarantee the formation of highly reactive radicals and oxidant species, resulting in high efficiency of pollutant treatment.…”

“…Among these factors, the costs of the process are very important. They include electrical energy consumption, which constitutes the main part of the operating costs [48,51]. PEC processes of wastewater treatment are regarded as consuming electrical energy and are usually characterized by the consumption of electrical energy per mass E EM (kWh/kg) or electrical energy per order E EO (kWh/m 3 /order), as described by the following equations [51,144]:…”

Energy Issues in Sustainable Urban Wastewater Management: Use, Demand Reduction and Recovery in the Urban Water Cycle

“…It has been shown that, in combination to conventional processes, they can achieve significant overall efficiency improvement not just towards removal of CECs but also of conventional contaminants [77]. Hence, Electron Beam and Plasma technologies could have a primary role in future strategies addressing emerging contaminants, contributing to optimized process energy demand [78].…”

Contaminants of emerging concern in aquatic environment: Occurrence, monitoring, fate, and risk assessment

“…Martin-Pozo et al (2019) provided a review of the determination of CECs in wastewater sludge samples. Capodaglio (2019) discussed the state of the art of high-energy oxidation-reduction processes for water purification and wastewater treatment, which could play an important role in future strategies addressing CECs. Joseph et al (2019) reviewed the studies on the removal of various CECs with different physicochemical properties by various nanoadsorbents based on mental-organic framework (MOF-NAs) under different water quality conditions and discussed the recent literature on the synthesis and regeneration of MOF-NAs, and removal of CECs during water and wastewater treatment processes.…”