Microplastic Identification in Domestic Wastewater-Treating Constructed Wetlands and Its Potential Usage in a Circular Economy

Mentions of microplastics (MPs) are increasingly frequent, for they are present in all environments, including wastewater. Knowing their possible harmful effects on the food chain, the fact that they appear in crops is concerning. The ways by which they are transported and stored, as well as their final destination, are still unclear. The issue of MPs in wastewater and how they are carried into agricultural crops are little-known facts. This study aims to evaluate whether horizontal subsurface flow wetlands with ornamental plants (Hippeastrum hybridum hort and Heliconia bihai marginata) can retain microplastics present in domestic wastewater while at the same time recirculating water for irrigation of the Phaseolus vulgaris crop. On average, the ornamental plants Hippeastrum hybridum hort and Heliconia bihai marginata removed contaminants such as COD, NH4+, TN, NO2−, TP, PO43−, and TSS, with an efficiency of 84% and 98%, respectively. The presence of MPs was identified via FTIR analysis and visual characterization in domestic wastewater, treated wastewater, and well water; the quality of the fruit for human consumption was determined using safety tests for Escherichia coli and Salmonella.