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.

The electrocoagulation (EC) process has been widely studied in recent years to remove a wide range of contaminants present in different types of water: fluorides, arsenic, heavy metals, organic matter, colorants, oils, and recently, pharmaceutical compounds. However, most of the studies have been aimed at understanding the process factors that have the most significant effect on efficiency, and these studies have been mainly on a batch process. Therefore, this review is focused on elucidating the current state of development of this process and the challenges it involves transferring to continuous processes and the recent exploration of its potential use in the removal of pharmaceutical contaminants and its implementation with other technologies.

Purpose: The effect of different initial carbon to nitrogen (C/N) ratios on the prevalence of Salmonella spp., fecal coliforms and helminth eggs over composts produced from several mixtures of maize straw (S) and dairy manure (M) was investigated. Methods: Four C/N ratios (21, 22, 27, and 38) were evaluated, including one with manure only (C/N 21). The composting process was performed under field conditions in northern Mexico. Results: The process lasted 51 days; Salmonella spp. was reduced 1–2 log (> 94%) in most treatments, except for the C/N ratio of 27 which achieved < 1 log reduction (about 35%). Fecal coliforms elimination was 3–4 log (> 99%) in all treatments while helminth eggs achieved < 1 log (72–87%, depending on treatment). In this study, the mixture with initial C/N ratio of 22 (25% S + 75% M), which had the lowest amount of straw, resulted in the highest elimination of Salmonella spp., fecal coliforms, and helminth eggs. This mix complied with current Mexican sanitary regulations for compost use. The composts produced from the other C/N ratios complied only with the limits for one or two of the microorganisms that were analyzed. Conclusions: The initial C/N ratios in compost from straw and manure influences microbial reduction. The final C/N of the mixes ranged from 14 to 16, indicative of stable compost. Compared to fecal coliforms, Salmonella spp. and helminth eggs were more resilient.