Emerging Pollutants in Wastewater, Advanced Oxidation Processes as an Alternative Treatment and Perspectives

Abstract

Emerging pollutants are present in wastewaters treated by conventional processes. Due to water cycle interactions, these contaminants have been reported in groundwater, surface water, and drinking waters. Since conventional processes cannot guarantee their removal or biotransformation, it is necessary to study processes that comply with complete elimination. The current literature review was conducted to describe and provide an overview of the available information about the most significant groups of emerging pollutants that could potentially be found in the wastewater and the environment. In addition, it describes the main entry and distribution pathways of emerging contaminants into the environment through the water and wastewater cycle, as well as some of the potential effects they may cause to flora, fauna, and humans. Relevant information on the SARS-CoV-2 virus and its potential spread through wastewater is included. Furthermore, it also outlines some of the Advanced Oxidation Processes (AOPs) used for the total or partial emerging pollutants removal, emphasizing the reaction mechanisms and process parameters that need to be considered. As well, some biological processes that, although slow, are effective for the biotransformation of some emerging contaminants and can be used in combination with advanced oxidation processes.

Photo‐Alternating Current‐Electro‐Fenton Process for Pollutant Removal and Energy Usage from Industrial Wastewater: Response Surface Approach Optimization of Operational Parameters

“…[1,5,6] AOPs based on electrochemical technology, also known as electrochemical advanced oxidation processes (EAOPs), have recently been established for the degradation of organic contaminants. [7][8][9] EAOPs are advantageous over other traditional treatment techniques owing to environmental sustainability since they are in compliance with the electrochemistry concept, which primarily involves electrons as the inherent clean reagent for all EAOPs. [10,11] Moreover, because of the simple equipment needed and the operation under mild conditions, EAOPs are relatively simple and safe.…”

“…[1,24] PEF process with the assistance of UV light is advantageous in accelerating the degradation process through the photo-reduction of Fe(III)hydroxyl species (Fe(OH) 2 + ) and photodecomposition of Fe(III)carboxylate intermediates (Fe(RCOO) 2 + ) in the working solution (eqs. (5)(6)(7)(8)). [24,25] A constraint of the PEF method is the need for an external power source to run the process.…”

“…Organic polltant þ hv ! Oxidation products (8) Where, Fe(OOCR) 2 + stands for Fe(III)-carboxylate complex ion.…”

Visible Light-Assisted Degradation of Sulfamethoxazole on 2D/0D Sulfur-Doped Bi2O3/MnO2 Z-Scheme Heterojunction Immobilized Photocatalysts

“…Numerous studies have been conducted worldwide to uncover alternate methods for the removal of PhACs from different water matrices, including advanced oxidation techniques that merit particular consideration. 6 In particular, the choice of heterogeneous photocatalysis is one of the most researched methods for removing PhACs and is guided by its stability, sustainability, low cost, and ease of operation. 7,8 Regardless of its advantages, existing photocatalytic systems face several challenges, including material recovery, recombi- nation of electron−hole pairs, a narrow range of light absorption, reactor design, the toxicity of degradation byproducts, and high cost.…”

“…Numerous studies have been conducted worldwide to uncover alternate methods for the removal of PhACs from different water matrices, including advanced oxidation techniques that merit particular consideration . In particular, the choice of heterogeneous photocatalysis is one of the most researched methods for removing PhACs and is guided by its stability, sustainability, low cost, and ease of operation. , Regardless of its advantages, existing photocatalytic systems face several challenges, including material recovery, recombination of electron–hole pairs, a narrow range of light absorption, reactor design, the toxicity of degradation byproducts, and high cost. ,, Recently, researchers have been addressing the majority of these limitations by developing suitable photocatalysts to overcome many of these drawbacks. , In addition, different modification approaches, including metal and nonmetal doping and formation of heterojunction, have been harnessed due to their ability to achieve high stability, excellent separation and migration of photoexcited charge carriers, and high specific surface area (SSA). , Among heterojunctions, the Z-scheme configuration is most preferred for the possibility of efficient charge transfer of photogenerated electrons from one semiconductor to the other and reducing charge recombination in order to account for the overall improvement in photocatalysis .…”