Removal of contaminants of emerging concern from wastewater by a combination of sunlight and chlorine

Abstract

Wastewater treatment plant (WWTP) are not designed to eliminate contaminants of emerging concern (CECs). This group of compounds is made up of remains of medicines, hormones, pesticides and personal hygiene products, among others, and is characterized by being organic, of anthropogenic origin, poorly biodegradable and are found in trace levels in secondary effluents. However, they can suppose a danger to the environment and people, especially if they are released into the aquatic environment or if the water from the treatment plants is used for agricultural irrigation or other applications involving human interaction. To achieve a significant attenuation of CECs in WWTPs and reduce the risks associated with this type of pollution, it is necessary to implement advanced water treatments such as Advanced Oxidation Processes (AOPs). This family of technologies is based on the generation of highly oxidizing species that can chemically destroy a wide variety of organic pollutants. Some of the most promising AOPs are those based on the use of ultraviolet light (UV) and weak oxidants, although the operating costs of these treatments are high due to much of the electricity requirements for the operation of the lamps. For this reason, attempts have been made to replace ultraviolet radiation with natural light from the Sun. The aim of the project is to evaluate the feasibility, both economic and technological, of a possible new AOP that combines chlorine and the use of sunlight as a source of radiation in the removal of CECs from wastewater. The basic aspects of the process, such as the kinetics associated with the degradation of pollutants, will be studied in a laboratory-scale experimental photochemical system. The aim is to combine pollutant degradation experiments with the analysis of residual oxidants and organic compounds using colorimetric techniques and liquid chromatography, respectively.