Advanced Oxidation Processes for Water and Wastewater Treatment: Developments, Challenges, and Opportunities

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Environmental and Green Processes".

Deadline for manuscript submissions: 20 May 2025 | Viewed by 5916

Special Issue Editors


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Guest Editor
Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Doha, Qatar
Interests: ozone; advanced oxidation processes; wastewater treatment; water reuse

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Guest Editor
Faculty of Engineering Technology, Universiti Malaysia Pahang, Pekan, Malaysia
Interests: wastewater treatment; membrane application; fine chemicals; biomass conversion; fouling analyses

Special Issue Information

Dear Colleagues,

Water scarcity and contamination are pressing issues that pose substantial threats to human health, ecosystems, and socio-economic stability. Effectively addressing these crises necessitates efficient water management, wastewater treatment, and promotion of water reuse. Advanced oxidation processes (AOPs) play a pivotal role in these efforts by efficiently breaking down contaminants, ensuring the safety of water for various uses, and enabling environmentally responsible discharge. AOPs present a promising alternative to conventional treatment methods, especially in their capacity to remove persistent pollutants, pharmaceutical residues, and emerging contaminants, which often challenge traditional treatment processes. While AOPs hold substantial potential for water treatment, they encounter various challenges. These encompass selecting the appropriate AOPs, optimizing catalysts, enhancing energy efficiencies, reducing costs, managing the generation of byproducts, and seamlessly integrating with existing treatment processes.

This Special Issue welcomes original research papers and review articles on AOP applications, including the following:

a. The utilization of AOPs in water treatment and wastewater reuse;
b. Advancements in novel materials and technologies related to AOPs;
c. Process optimization, integration, and techno-economic analyses of AOPs;
d. In-depth scientific investigations into various AOP-based technologies, such as electrochemical oxidation, anodic oxidation processes, Fenton, photo-Fenton, UV, catalytic, photo-catalytic, sulfate radicals, and others;
e. Evaluations of the toxicity of oxidation byproducts;
f. Assessments of AOPs in pilot and full-scale applications.

Dr. Jayaprakash Saththasivam
Prof. Dr. A. M. Mimi Sakinah
Guest Editors

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Keywords

  • advanced oxidation processes
  • photocatalysis
  • ozone
  • chemicals of emerging concern
  • chemical oxidation
  • hydroxyl radicals
  • catalytic oxidation
  • environmental remediation
  • micropollutant removal
  • reactive radical species
  • water treatment and reuse
  • oxidation byproducts

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Published Papers (5 papers)

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Research

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13 pages, 2178 KiB  
Article
Decolorization of Rhodamine B by Fenton Processes Enhanced by Cysteine and Hydroxylamine Reducers
by Ana Daura Concilia Alves Fernandes and André Aguiar
Processes 2025, 13(1), 185; https://doi.org/10.3390/pr13010185 - 10 Jan 2025
Viewed by 580
Abstract
Fe3+-reducing agents have been used to enhance Fenton process efficiency in degrading dyes commonly found in textile wastewater. The present work consisted of evaluating the effect of two compounds that reduce Fe3+, cysteine (Cys) and hydroxylamine (HA), on the [...] Read more.
Fe3+-reducing agents have been used to enhance Fenton process efficiency in degrading dyes commonly found in textile wastewater. The present work consisted of evaluating the effect of two compounds that reduce Fe3+, cysteine (Cys) and hydroxylamine (HA), on the oxidative decolorization of Rhodamine B dye by homogeneous Fenton processes, Fe2+/H2O2 and Fe3+/H2O2. The kinetics of the reactions were analyzed to better interpret the decolorization data. Due to the addition of the two reducing agents and the increase in temperature, there were increases in decolorization and the values of the reaction rate constants. The first-order reaction kinetic model was the one that best fit the experimental data. Comparing the two reducers, Cys was more effective. As an example, for reactions initially containing Fe2+ in just 20 min and at a temperature of 30 °C, the HA and Cys reducers increased the decolorization from 33% to 48% and 64%, respectively. It was possible to verify a decrease in the activation energy (Ea) due to the presence of the two reducing agents, but more significantly for reactions containing Fe3+. The values of Ea to Fe3+/H2O2, Fe3+/H2O2/Cys, and Fe3+/H2O2/HA were 85.7, 52.2, and 50.9 kJ∙mol−1, respectively. This way, it can be inferred that the two reducers decreased the energy barrier to enhance the Fenton-based oxidation of Rhodamine B. Full article
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16 pages, 3491 KiB  
Article
Impact of the UV/H2O2 Process on Assimilable Organic Carbon and Trihalomethane Formation in Cyanobacteria-Contaminated Waters
by Luciana Verissimo Siquerolo, Rúbia Martins Bernardes Ramos, Pablo Inocêncio Monteiro, Guilherme Ferreira Silveira, Fatima de Jesus Bassetti and Lucila Adriani de Almeida Coral
Processes 2025, 13(1), 23; https://doi.org/10.3390/pr13010023 - 26 Dec 2024
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Abstract
The organic material from cyanobacteria is a significant precursor to the generation of disinfection byproducts. This study’s aim was to evaluate the formation of assimilable organic carbon (AOC) in water contaminated with cyanobacteria. Furthermore, the formation of AOC was related to the generation [...] Read more.
The organic material from cyanobacteria is a significant precursor to the generation of disinfection byproducts. This study’s aim was to evaluate the formation of assimilable organic carbon (AOC) in water contaminated with cyanobacteria. Furthermore, the formation of AOC was related to the generation of trihalomethanes (THMs) and dissolved organic carbon (DOC). The advanced oxidation process was caISOrried out by exposing Microcystis aeruginosa cells (250,000 cells mL−1) to different peroxide dosages (10 to 100 mg L−1) under ultraviolet radiation. Pseudomonas fluorescens (P-17), Spirillum sp. (NOX), and flow cytometry were used to determine the AOC concentration. The formation of AOC and THMs during the UV/H2O2 process was not directly related. The AOC concentration increased with low H2O2 doses and decreased at higher concentrations, while the levels of THMs decreased regardless of the AOC formed. After oxidation, the DOC concentration decreased, along with the concentration of THMs. Additionally, it was observed that the behavior of DOC and AOC is inversely proportional. These results suggest that the oxidation process has a complex effect on organic matter, influencing byproduct formation and AOC availability. Moreover, these findings highlight the importance of carefully monitoring and controlling the oxidation processes to better understand their impact on water treatment and byproduct formation. Full article
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18 pages, 3996 KiB  
Article
Electrochemical Oxidation of Glyphosate Using Graphite Rod Electrodes: Impact of Acetic Acid Pretreatment on Degradation Efficiency
by José Treviño-Reséndez, Erick Soto-Hernández, Luis A. Godínez, Irma Robles, Yunny Meas Vong and Josué D. García-Espinoza
Processes 2024, 12(11), 2359; https://doi.org/10.3390/pr12112359 - 28 Oct 2024
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Abstract
The uncontrolled use of herbicides such as glyphosate (GLY) (N-phosphonomethylglycine) in agricultural production has resulted in its presence in water bodies and in negative impacts on the environment and public health. On the frame of understanding the interaction between GLY and graphite rod [...] Read more.
The uncontrolled use of herbicides such as glyphosate (GLY) (N-phosphonomethylglycine) in agricultural production has resulted in its presence in water bodies and in negative impacts on the environment and public health. On the frame of understanding the interaction between GLY and graphite rod surfaces, this contribution relies on the study of electrochemical responses of different GLY concentrations by cyclic voltammetry under both open and closed-circuit conditions. Furthermore, the effect of the electrodes’ electrochemical pretreatment with acetic acid on the double-layer capacitance and the subsequent surface functionalization of the graphite rod materials were evaluated. The increment in GLY concentration showed a decrease in the electrochemical oxidation response associated with the adsorption of the contaminant on the surface of the graphite rod electrode and the concomitant blockage of the active sites. Electrochemical pretreatment of the electrodes with acetic acid and GLY concentration play crucial roles in electric double-layer formation due to their ability to interact with both positive and negative electrical charges. By means of optical microscope observations and Fourier Transform Infrared Spectroscopy analysis, it was possible to detect the formation of oxygenated functional groups on the electrode surfaces after the electrochemical pretreatment. Through a 23 factorial design analysis in repetition, the factors significant in the degradation of GLY were identified. The high degradation of GLY with the pretreated electrodes can be attributed to the preferential adsorption of the zwitterionic molecule at the interface, which allowed great direct oxidation of the contaminant on the anode’s surface. Full article
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28 pages, 14763 KiB  
Article
Data-Based Modeling, Multi-Objective Optimization, and Multi-Criterion Decision-Making to Maximize the Electro-Oxidation of Metoprolol over Boron-Doped Diamond Electrodes in a Flow-By Reactor
by Alejandro Regalado-Méndez, Diego Vizarretea-Vásquez, Edson E. Robles-Gómez, Reyna Natividad, Carlos J. Escudero and Ever Peralta-Reyes
Processes 2024, 12(9), 1958; https://doi.org/10.3390/pr12091958 - 12 Sep 2024
Cited by 3 | Viewed by 1481
Abstract
Metoprolol is a cardioselective beta-blocker drug often used to treat hypertension, but it is considered as a hazardous organic persistent contaminant in wastewater. In this study, a 2.5 L solution of metoprolol (50 mg/L) underwent electro-oxidation in a flow-by reactor using boron-doped diamond [...] Read more.
Metoprolol is a cardioselective beta-blocker drug often used to treat hypertension, but it is considered as a hazardous organic persistent contaminant in wastewater. In this study, a 2.5 L solution of metoprolol (50 mg/L) underwent electro-oxidation in a flow-by reactor using boron-doped diamond electrodes in the batch recirculation mode. The study used multi-objective optimization and multi-criterion decision-making to determine the optimal operating parameters. The response surface methodology and a central composite rotatable design were used with three factors (pH0: 5–8, I: 2.5–4 A, and Q: 0.8–1.7 L/min) to model the chemical oxygen demand’s (COD’s) removal efficiency and the total organic carbon’s (TOC’s) removal efficiency. The experimental responses were modeled by reduced third- and second-order polynomials with determination coefficients (R2) of 0.9816 and 0.9430. The optimal operating parameters were found to be pH0 5, an I value of 3.84 A, and a Q value of 0.8 L/min with an electrolysis time of 7.5 h, resulting in a maximum COD removal efficiency of 60.8% and a TOC removal efficiency of 90.1%. The specific energy consumption was calculated as 9.61 kWh/mg of TOC, with a total operating cost of 0.77 USD/L. In conclusion, this study showed that the electrochemical process is efficient and reliable for treating wastewater containing metoprolol. Full article
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Review

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13 pages, 1017 KiB  
Review
Inactivation of Aspergillus Species and Degradation of Aflatoxins in Water Using Photocatalysis and Titanium Dioxide
by Gabriela Elizabeth Quintanilla-Villanueva, Donato Luna-Moreno, Raisa Estefanía Núñez-Salas, Melissa Marlene Rodríguez-Delgado and Juan Francisco Villarreal-Chiu
Processes 2024, 12(12), 2673; https://doi.org/10.3390/pr12122673 - 27 Nov 2024
Cited by 1 | Viewed by 1139
Abstract
Aflatoxins (AF) are highly toxic secondary metabolites produced by various species of Aspergillus, posing significant health risks to humans and animals. The four most prominent types are aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1), and aflatoxin G2 (AFG2). These mycotoxins [...] Read more.
Aflatoxins (AF) are highly toxic secondary metabolites produced by various species of Aspergillus, posing significant health risks to humans and animals. The four most prominent types are aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1), and aflatoxin G2 (AFG2). These mycotoxins are prevalent in various environments, including water sources and food products. Among these mycotoxins, AFB1 is recognized as the most toxic, mutagenic, and carcinogenic to humans. Consequently, most efforts to mitigate the impact of AF have been focused on AFB1, with photocatalysis emerging as a promising solution. Recent research has demonstrated that using semiconductor photocatalysis, particularly titanium dioxide (TiO2), combined with UV–visible irradiation significantly enhances the efficiency of AF degradation. TiO2 is noted for its high activity under UV irradiation, non-toxicity, and excellent long-term stability, making it a favorable choice for photocatalytic applications. Furthermore, TiO2 combined with visible light has demonstrated the ability to reduce AF contamination in food products. This article summarizes the working conditions and degradation rates achieved, as well as the advantages, limitations, and areas of opportunity of these methodologies for the degradation of AF and preventing their production, thereby enhancing food and water safety. Full article
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