Feasibility of rapid gravity filtration and membrane ultrafiltration for the removal of microplastics and microlitter in sewage and wastewater from plastic industry

[EN] Wastewater treatment plants (WWTPs) act as barriers in reducing uncontrolled microplastic and microlitter (MP-ML) emissions from both urban and industrial wastewaters. Despite removing most of the MP-ML, large quantities of this waste still enter the environment through WWTP effluents, which means further post-treatment technologies are needed. This study contains a technical evaluation of MP-ML removal from urban wastewater (UWW) and from the wastewater from the recycling plastic industry (PIWW) using two different pilot-scale post-treatment systems: rapid gravity filtration (RGF) and ultrafiltration (UF) membranes. The MP-ML mass concentrations contained in UWW and PIWW were measured by a simplified method adapted for the long-term monitoring of WWTP operations. The method was validated on standard samples. Despite the RGF system consumed less energy than UF treating UWW (0.097 kWh·m-3 and 0.156 kWh·m-3, respectively), RGF was not efficient enough to properly decrease the risk of MP-ML emissions (39.5 ± 34.6% of MP-ML removal). With respect to PIWW, the energy consumption of the UF plant decreased up to 0.059 kWh·m-3. The combination of RGF and UF technologies was expected to reduce membrane fouling but it did not show significant differences in the mid-term operation.