Treatment of greywater coming from a food court using adsorption and advanced oxidation processes

Abstract

The increase in the demand for water has recrudesced water scarcity in several places of the world, which has been intensified by the lack of rainfall, generating a water crisis, being very important to evaluate the treatment to allow the reuse of greywater. This is the first study focused on the removal of pollutants present in greywater using a pretreatment system based on ozone and solar irradiation. A series of treatments were addressed to evaluate the depuration of greywater coming from the dishwashing of a university dining hall. Notable findings of the study include several aspects such as a very high colour removal using sedimentation and, filtration and flotation process, with an overall colour removal of 91.8 %. The adsorption process removed a higher amount of surfactants with dried compost as adsorbent compared to fly ash or zeolite, with surfactant removal rates of 50.8 %, 7.8 %, and 9.0 %, respectively. Eliminating oil and grease from the greywater was studied with a solar photoreactor coupled with an ozonation process and configured in different ways. When ozone was incorporated into the vertical ozonation tube, and greywater was pumped to mix it with the ozone gas to pump the resulting mix to the borosilicate tube, oil and grease removal was 84.1 %. These treatment processes offer an effective solution for removing pollutants present in greywater; however, further studies and optimisation of operational conditions are required to enhance the efficiency of the treatment.