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Occurrence and fate of micropollutants in surface waters

Abstract:

Micropollutants or microcontaminants or emerging contaminants are compounds that are divided into five major groups such as polar pesticides, perfluorinated compounds, chlorinated kerosenes, personal hygiene products, and drugs that have gone unnoticed, because of their low concentrations in water from ngL−1 to μgL−1. These can behave as endocrine disruptors due to their bioaccumulation, having harmful effects on human health such as fertility problems, growth, metabolic variations, and hormonal disorders; in addition to this, they cause environmental problems, since their elimination is not contemplated within the wastewater treatment plants due to the design they have; hence, they can eliminate nutrients with concentrations greater than gL−1. These contaminants can be found in both surface water and groundwater and have been increasing in parallel with the production of chemicals considered potentially dangerous. The levels are variable examples; in the tributaries, pharmaceutical compounds are present in low concentrations compared to the concentration levels that are present in the effluent. So its occurrence is dependent on the weather station, which increases during dry season and decreases in wet season, within the contamination of micropollutants contributed by the pharmaceutical industry are the nonsteroidal antiinflammatory drugs, sulfamethoxazole, triclosan and carbamazepine, being the main source of contamination. The effluents of the hospitals and the industries that contribute with high levels of microcontaminants are the agrochemicals; at present, around 16 million different pesticides were producing and its main problem is most of these are polar. The presence of emerging pollutants in the aquatic environment with low concentrations and the fact that they cannot be removed by conventional wastewater treatment processes pose new challenges in terms of the appropriate selection of technologies from technical, economic, and environmental, because many of them are found in everyday products such as pharmaceuticals for human and veterinary use, personal care products, plasticizers, and various industrial additives that are continually released into the environment and accumulate over time. There are different treatments for the elimination of emerging pollutants, physicochemical, biological, membrane, combined, advanced, and membrane nanofiltration. The removal, treatment, and detection of wastewater transformation products are difficult tasks due to their complexity in water samples. The ability to remove contaminants depends on various factors, such as physicochemical properties, biological persistence of the individual compound, technology, process conditions such as temperature and seasonal variability, hydraulic retention time, and applied sludge. Removal and detection of emerging pollutants and their transformation products in natural and drinking waters are difficult tasks due to the complexity of contaminants in water samples. Future trends in removing emerging pollutants from the water will lie on the advanced oxidation method, as it can effectively degrade the pollutants. At present, feasible techniques are still being implemented to remove emerging pollutants or at least reduce them below regulated levels, in addition to researchers to fully describe the mechanisms and optimize key parameters related to the removal of emerging pollutants from water in real applications.