Wastewater Treatment by Constructed Wetland Eco-Technology: Influence of Mineral and Plastic Materials as Filter Media and Tropical Ornamental Plants

Abstract

Constructed wetlands (CWs) are sustainable technologies where the channels are filled with porous material and plants, which collectively remove pollutants, depending on the type of substrate and vegetation. This study evaluated CWs and their functionality by comparing three ornamental plants (Canna indica, Cyperus papyrus, and Hedychium coronarium) as a phytoremediation process of wastewater, in CWs filled with layers of porous stone−tepezil−plastic residues−soil (S-A), or in microcosms with layers of porous stone−tepezil−soil without the presence of plastic (S-B). The findings during 180 days showed that the removals of pollutants (chemical oxygen demand (COD), total solids suspended (TSS), nitrogen as ammonium (N-NH4), as nitrate (N-NO3), and phosphate (P-PO4) were 20%−60% higher in microcosms with plants than in the absence of plants. Statistical differences were not observed when comparing removal effects among S-A and S-B, indicating that plastic residues as filter material in CWs did not affect the pollutant removal, growth, flowering, and shoots of plants. The use of plastic residues as filter may represent a less costly alternative in CW establishments. Dependence on N-NH4 and TSS removal was observed according to plant species. The three species used are suitable for using in CWs as wastewater treatment. In addition, the ornamental plants could generate interest for a commercial option.

Keywords

• eco-technology
• phytoremediation
• plastic residues
• ornamental vegetation
• pollutant removal