Removal of Pollutants from Domestic Wastewater Using Macrophyte Filters Planted with Echinochloa pyramidalis (Lam.) Hutch

Abstract

Domestic wastewater contains high concentrations of organic matter, nutrients, suspended solids, and trace metals that can cause significant environmental pollution if discharged without treatment. This study evaluated the efficiency of a macrophyte-based filtration system planted with Echinochloa pyramidalis (Lam.) Hutch for the treatment of domestic wastewater collected from student residences at Marien Ngouabi University, Republic of Congo. The experimental setup consisted of two pilot-scale filters: a vegetated filter planted with E. pyramidalis and an unvegetated filter used as a control. Wastewater was applied intermittently at seven-day intervals over six months, and physicochemical parameters were monitored to assess treatment performance. The planted filter demonstrated superior pollutant removal compared with the control filter. Average removal efficiencies achieved by the vegetated system were 76.97% for total suspended solids (TSS), 76.24% for turbidity, 78.49% for chemical oxygen demand (COD), 92.69% for nitrate (NO₃⁻), 78.28% for ammonium (NH₄⁺), 81.99% for orthophosphate (PO₄³⁻), 91.04% for nickel, 82.50% for chromium, and 94.55% for copper. In comparison, the control filter achieved removal efficiencies of 60.13%, 58.29%, 52.66%, 36.74%, 48.93%, 50.97%, 67.08%, 63.54%, and 63.38%, respectively. The results indicate that E. pyramidalis significantly enhances the removal of organic, nutrient, and metal pollutants through filtration, microbial activity, and plant uptake mechanisms. The study demonstrates the potential of E. pyramidalis-based constructed wetland systems as an efficient, low-cost, and environmentally sustainable technology for domestic wastewater treatment in developing regions.