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.

Since the conventional processes employed in most wastewater treatment plants (WWTPs) worldwide are not designed to entirely remove or oxidize emerging pollutants, which, due to their incidence and persistence, can cause damage to both the environment and human health, several options for their degradation and removal have emerged. Coupling the advanced Fenton oxidation process as a polishing or tertiary wastewater treatment alternative within conventional WWTP processes stands out among the treatment options. Therefore, the main objective of this research was to evaluate, at the laboratory level, the ability of the advanced Fenton oxidation process to oxidize triclosan, ibuprofen, DEET (N, N-diethyl-meta-toluamide), carbamazepine, caffeine, and acesulfame-K, which represent several groups of emerging pollutants in real wastewater from the second settling tank of a municipal WWTP. The compound used as a catalyst (Fe²⁺) supplier in the advanced Fenton oxidation process was ferrous sulfate heptahydrate (FeSO₄•7H₂O). The results obtained upon application showed that the advanced Fenton oxidation process could simultaneously oxidize and remove practically the total concentration of the above-mentioned emerging pollutants, except for DEET (85.21%), in conjunction with the chemical oxygen demand (COD), total suspended solids (TSS), and fecal coliforms (FC, pathogen group) in the effluent generated by the advanced Fenton oxidation process.

Real wastewater contains emerging contaminants that pose problems for flora, fauna, and human health. Conventional wastewater treatment processes, such as the activated sludge process and aerated lagoons, which are commonly used worldwide, cannot remove these contaminants. Therefore, this review analyzes the application of the Fenton process and its variants—homogeneous Fenton, photo-Fenton, Fenton-like, heterogeneous Fenton, and electro-Fenton—to remove various emerging contaminants belonging to different groups, such as pharmaceuticals, personal care products, perfluoroalkyl and polyfluoroalkyl substances (PFASs), etc., from wastewater. The review focuses on the reaction mechanisms, application considerations, parameters, and future perspectives of these processes. The compiled information shows that the Fenton process and most of its variants can successfully remove emerging contaminants from different types of aqueous matrices. However, improvements are still needed in terms of performance and application for treating real wastewater on a macro scale.

Domestic and industrial wastewaters are complex matrices that contain a large variety of pollutants. Consequently, the conventional processes at wastewater treatment plants (WWTPs) cannot remove these. These pollutants remain in the effluent and are discharged into different environmental compartments worldwide, generating a range of negative impacts on the environment and human health. In this chapter, general features and the application of the most common advanced oxidation processes (AOPs) for the treatment of domestic and industrial wastewater are described. Also, the feasibility of scaling up advanced oxidation processes for pollutants removal (emerging and conventional) and the advantages and complications of each type of advanced oxidation process when applied to wastewater treatment (domestic and industrial) are shown.

This chapter carries out a critical analysis of the literature review on the presence of pharmaceuticals in wastewater, their classification (e.g., Nonsteroidal Anti-inflammatory Drugs, antibiotics. etc.), their distribution in the environment, their toxicity, their endocrine-disrupting power, the antimicrobial resistance they may promote, and the most commonly used methods for detecting them in wastewater. Additionally, some of the most used physical, physicochemical, biological, and chemical alternatives (processes) for treating these emerging contaminants (pharmaceuticals) are evaluated and compared. Finally, in this chapter also the most effective process (treatment method) is determined and recommended as a treatment future trend based on criteria such as the process’ capability to remove these compounds, operating costs process, the ease of scaling up of the treatment, the byproducts treatment generate (oxidation or degradation products), and treatment ability to adapt to conventional wastewater treatment processes (e.g., oxidation lagoons and activated sludge processes).