Advancements in Electrochemical Advanced Oxidation Processes: Addressing Emerging Contaminants in Latin America
Authors: Sandoval Miguel A , Salazar Ricardo , Calzadilla Wendy , Vidal Jorge , Brillas Enric 
Published: December 2024

Water contamination by persistent organic pollutants is one of the main challenges to be solved for a desired sustainable society. The occurrence of emerging pollutants (CECs), even at low concentrations (from μg L-1 to ng L-1), negatively affects species' life cycles and water quality, impacting the population's water supply. Inorganic pollutants such as arsenic, sulfates, phosphates, iron, lead, and mercury, often accompany emerging pollutants, further reducing effluent quality. In Latin America, the occurrence and problematic nature CECs pose significant challenges to environmental and public health. Rapid urbanization and industrialization, and agricultural intensification contribute to the release of a diverse range of emerging pollutants into the environment. Therefore, their study has recently been gaining wide interest in the scientific community. Various factors contribute to water pollution, including direct industrial and domestic discharge without proper treatment, deteriorating sewage pipes causing effluent infiltration, and stormwater percolating through solid waste disposal sites. These pollutants, along with their degradation by-products, are not fully biodegradable and persist in water bodies, leading to bioaccumulation in marine and freshwater species and posing potential hazards to human health through contaminated food consumption.

Over the past two decades, scientific research in Latin America has evolved to study emerging pollutants in various biological samples and environmental matrices, but further collaboration among neighboring countries is needed. In recent years, Brazil, Chile, and Colombia are the main countries that have conducted research on the presence of these pollutants in biological and aquatic compartments. However, economic issues and high treatment/monitoring costs result in data absence in countries like Haiti, Cuba, Venezuela, Nicaragua, and Honduras. Figure 1 shows CECs detection in different Latin America´s countries.

Figure 1. Overview of the detection of CECs in Latin America in different matrices of biological and environmental origin [1].

Analytical methods used in Latin America for determining emerging pollutants have evolved towards environmentally friendly techniques with shorter development times and lower solvent consumption. Most common analytical methodologies for identifying these compounds were HPLC and GC coupled with mass spectrometry. However, studies remain insufficient compared to other regions, partly due to equipment absence and focus on target analysis, potentially biased information. Data gathered indicated that pharmaceuticals, pesticides, and personal care products are the most assessed CECs in Latin America, being the most common compounds the followings: atrazine, acenaphthene, caffeine, carbamazepine, ciprofloxacin, diclofenac, diuron, estrone, losartan, sulfamethoxazole, and trimethoprim.

Effective wastewater management plays a fundamental role in preserving public and ecological health. However, the use of outdated wastewater treatment plants (WWTPs) or with limited disposal strategies/practices is the main essential factor for an unhealthy ecosystem because a large number of organic micropollutants and their transformations products (TPs) are constantly released into the aquatic environment during their life cycle. Most CECs’ monitoring and detection were observed near to urban areas which confirm the out-of-date wastewater treatment plants and sanitization infrastructures limiting the removal of these pollutants. Therefore, the implementation of tertiary treatment should be required.

Global efforts to eliminate or at least control CECs have increased. To remove emerging pollutants from wastewater, several treatments such as adsorption, physicochemical processes, constructed wetlands, membrane technologies, advanced oxidation processes (AOPs), electrochemical advanced oxidation processes (EAOPs), and hybrid treatments have been assessed, each one with their cons and pros. Regarding EAOPs, they represent a promising and innovative approach. Through the generation of reactive oxygen species and other powerful oxidants at the electrode surface, EAOPs facilitates the breakdown of diverse organic pollutants. This method offers advantages such as high efficiency, selectivity, and the ability to target a wide range of CECs. Moreover, EAOP can be particularly beneficial for treating complex wastewater matrices where traditional treatment methods may fall short. Moreover, these electrochemical processes promote sustainable water management practices, but further research is needed to scale up laboratory findings to pre-industrial setups.

Addressing the occurrence of contaminants of emerging concern in Latin America requires a comprehensive approach that involves strengthened regulations, improved monitoring infrastructure, and sustainable waste management practices to safeguard both environmental and human well-being. In addition, circular economy approaches have shifted focus towards value-added by-products from wastewater treatment, but a unified regulation across Latin America is crucial for mitigating environmental impacts and maximizing recycling and reuse benefits. Future research should include continuous wastewater testing, studying new contaminants, elucidating degradation mechanisms, assessing treatment effectiveness and toxicity, promoting renewable energy use, optimizing treatment methods, developing new reactor designs, enhancing plant control and automation, fostering university-industry-government collaboration, and implementing regional monitoring plans and standardized policies.

References.

[1] Sandoval, M., et al., Environ, Pollut. 345, 123397, 2024.

Figure 1