Removal of Micropollutants by Ozone-Based Processes

Abstract

Micropollutants and emerging substances pose a serious problem to environmental sustainability and remediation, due to their widespread use and applications in everyday life. This group of chemicals is diverse but with common toxic and harmful properties. Their concentration in the environment is often very low; however, due to their recalcitrant nature, they are persistent in air, water, and soil. From an engineering point of view, the challenge is not straightforward. It is difficult to remove these contaminants from complex mixtures of substances by conventional methods used in wastewater and drinking water treatment. Ozonation and ozone-based AOPs are accepted processes of degradation of resistant substances or at least enhancement of their biodegradability. The aim of this review paper is to present research trends aimed at solving problems in the research and application of ozone-based processes in the removal of micropollutants from wastewater, thus preventing leakage of harmful substances into surface water, soil, and groundwater and facilitating the reuse of wastewater. Priority substances, micropollutants and emerging pollutants, as well as processes and technologies for their transformation and elimination, are briefly specified. Results obtained by the authors in solving research projects that were aimed at eliminating selected micropollutants by ozonation and ozone-based AOPs are also presented. This review focuses on selected alkylphenols, petroleum substances, and organochlorine pesticides.

The Oxidation Mechanism of Aniline by Ozone Water and Ozone Micro-nano Bubble Water and Its Influencing Factors

“…The k1 value for OMNBW and OW were 0.016 min -1 and 0.033 min -1 respectively, which showed that the self-decomposition of ozone in OMNBW was much slower than that in OW. Previous studies showed that the half-life of ozone in the gas phase was about twice longer than that in the liquid phase (Derco et al 2021). When pressurized water containing ozone was released into the tank, a large fraction of ozone in OMNBW still existed in the gas phase, and then gradually dissolved in water with the disappearance of bubbles (Fujioka et al 2021), which led to a longer half-life of ozone in OMNBW.…”

“…In addition, a higher pH would also increase the lifetime of MNBs, because MNBs became more negative and had stronger repulsive force (Hamamoto et al 2018). However, the higher pH during ozonation would also lead to the instability of ozone molecules (Derco et al 2021), which further resulted in the quick decrease of aqueous ozone concentration.…”

“…Compared with OW, OMNBW produced more O2 •− , which indicates that OMNBW could trigger more chain reactions in the degradation of aniline. In addition, when pH was neutral or alkaline, the indirect oxidation by O2 •− was the main oxidation pathway (Beltran et al 1994, Derco et al 2021).…”

Clay, Zeolite and Oxide Minerals: Natural Catalytic Materials for the Ozonation of Organic Pollutants

“…The ozonation technology is especially attractive for the treatment of micropollutants, which despite their relatively low concentrations (µg/L to ng/L), have significant negative effects on ecosystems and humans. Conventional mechanical–biological wastewater treatment plants are unable to completely remove most micropollutants, so ozonation and other ozonation-based processes can be used as a single-step treatment approach, as a pretreatment method followed by other conventional methods, or as a post-treatment step to achieve effluent limits [ 28 ].…”

“…The degradation efficiency of AOPs is the result of the combined effect of water matrix components, which may have a neutral, inhibitory or supportive effect on the reaction mechanism [ 28 ]. Organic species can serve either as inhibitors (by exposure to light, capture or adsorption) or as promoters (increasing indirect photolysis or catalyst regeneration) [ 28 ].…”