Identification of micropollutants from graywater of different complexity and remediation using multilayered membranes

Graywater reuse is one of the important concepts in attaining water sustainability. A major challenge in this area is to realize various components present in graywater. The present study involves the identification of the chemical components of graywater collected from three different environments and to investigate the efficiency of removal of some of these chemical components using ultrafiltration membranes (polyelectrolyte multilayer (PEM) membranes). The chemical components were analyzed using liquid chromatography connected with quadrupole time-of-flight (UPLC-Q-ToF-MS). A number of micropollutants including surfactants and certain contaminants of emerging concern (CECs) were identified from these samples. Out of 16 compounds identified, 13 were surfactants and the remaining were caffeine, oxybenzone, and benzophenone. These surfactants are mostly the ingredients of various detergents. Low-pressure filtration studies of the collected samples were carried out utilizing chitosan/polyacrylic acid (CHI/PAA) multilayer membranes. A 5.5 bilayer membrane showed more than 95% rejection of the identified compounds in the selected samples and significant improvement in the water quality parameters. This demonstrates that the membrane used in this work is effective in the removal of various chemicals from graywater as well as enhancing the water quality.