Intermittent sand filtration for removal of microplastics from water: a laboratory-scale study

Microplastics have become one of the most important environmental problems in recent years. These pollutants come from everyday human activities, both industrial and domestic, and if not properly managed, can end up in the environment, with negative consequences for the ecosystem. One of the most important pathways for these microplastics to enter the environment are the discharges from wastewater treatment plants. Although a high removal of microplastics can be achieved with conventional treatments, these are not specifically designed for the removal of this pollutants, therefore large amounts of them are discharged together with the treated wastewater. The use of advanced treatments such as intermittent sand filtration can enable higher removal of microplastics from the water line, reducing pollution in natural water bodies, improving the water quality and allowing reuse of the treated water as a by-product with a low operating and investment costs. To understand and analyse the performance of this advanced treatment in removing microplastics, three laboratory-scale filters, filled with three different substrates -silica sand, two halves of sand and coke, and coke- were tested. Synthetic wastewater with a known amount of polypropylene microplastics and real wastewater from the secondary settler were used to study the efficiency of the filters. The samples were analysed before and after treatment in order to quantify the microplastics existing, classify them according to their morphology and identify the most abundant plastic polymers in the case of the real wastewater samples. This provided a preliminary analysis of the efficiency of this technology, the behaviour of different substrates in the removal of microplastics, the removal mechanisms depending on their morphology and their feasibility as a full-scale plant in a real, small wastewater treatment plant. Also see: https://micro2022.sciencesconf.org/426767/document