Sulfate Radical Technologies as Tertiary Treatment for the Removal of Emerging Contaminants from Wastewater

Abstract

Abstract:Water scarcity and water pollution is a worldwide problem and has driven research into eco-friendly and low-energy cost efficient remediation. The reuse of wastewater for non-potable purpose after proper treatment is the only sustainable solution to the problem. Advanced oxidation processes (AOP) based on the in-situ generation of hydroxyl radicals have been intensively investigated for this purpose as a treatment step to achieve wastewater reuse. The main degradation mechanism of AOPs is based on the reaction of hydroxyl radicals with dissolved organic matter. However, hydroxyl radicals follow unselective multi-step pathways, limiting their efficiency in complex environmental matrices. To overcome such limitations, AOP treatment, based on generation of sulfate radicals, has been developed and widely investigated. This current mini-review will cover the most recent developments regarding emerging contaminant removal, i.e., organic micropollutants, using sulfate radicals generated by active persulfate or peroxymonosulfate, with a focus on an application to wastewater effluents for possible wastewater reuse.

Advanced Oxidation Processes for Water and Wastewater Viral Disinfection. A Systematic Review

“…For the photo-Fenton process, irradiation with sunlight or an artificial light source is required to enhance the treatment efficiency of the respective dark reaction by the photoreduction of Fe 3+ to Fe 2+ and the additional production of hydroxyl radicals. A drawback of this process is the additional cost for artificial irradiation (Brienza & Katsoyiannis, 2017 ). To overcome the limitations associated with homogeneous Fenton processes (Table 3 ), including the need to operate at highly acidic conditions, production of large amounts of iron-containing sludge, need to re-adjust the treated effluent to near-neutral conditions, heterogeneous Fenton processes are used based on transition metal catalysts (e.g.…”

“…It is mainly based on semiconductors that are sensitive to the UVA and/or visible regions of the solar spectrum and, thus, the disinfection processes are based on the photoinduced electron–hole pairs on the excited semiconductor to produce different ROS (Chen et al, 2021 ). Numerous semiconductors have been applied but titanium dioxide (either as such or in various modified forms) has been extensively used due to its interesting characteristics (chemical inertness, high photoactivity, non-toxicity, low cost) (Brienza & Katsoyiannis, 2017 ).…”

“…(Chen et al, 2021 ). Ozone-based AOPs are characterized by elevated capital and operating costs, and high electric power consumption besides other drawbacks, such as low water solubility of ozone and formation of hazardous by-products (Table 3 ) (Brienza & Katsoyiannis, 2017 ; Rasalingam et al, 2014 ).…”

Superhydrophilic graphene oxide/electrospun cellulose nanofibre for efficient adsorption of organophosphorus pesticides from environmental samples

“…Since the OPPs concentration in the real samples are in trace amounts, various techniques have been developed like photocatalysis, oxidation [7], coagulation and flocculation [4], ion-exchange [4] and adsorption [10] for the adsorption of these pesticides. Adsorption of these pesticides by using the oxidation method is difficult as this method has significant limitations, such as the massive production of iron sludge, and high-cost requirements [11]. Coagulation and flocculation of pesticides produces large amounts of sludge at their disposal which becomes a problem [12].…”

Oxidative decolorization of a malachite green oxalate dye through the Photochemical Advanced Oxidation Processes

“…In order to overcome such limitation of • OH radical based AOPs (HR-AOPs), new methodology was adopted, called as sulphate radical based AOPs (SR-AOPs). It has been used for removal of contaminants in wastewater and extensively investigated (Brienza et al, 2017). In this study, Malachite Green Oxalate (MGO) dye was chosen as a target water pollutant.…”