Use of native macrophyte <i>Echinodorus subalatus</i> for grey water treatment applying alternative bed substrate in constructed wetlands

Two vertical flow constructed wetland (VFCW 1 and VFCW 2) with native macrophyte <i>Echinodorus subalatus</i> (Mart.) were operated. In VFCW 1, the substrates used were ceramic brick, washed sand, seashells (<i>Anomalocardia brasiliana</i>), and ceramic brick and sand in VFCW 2. The system was operated for 74 days, in batches, with cycles of 168 h, and fed with synthetic grey water. The presence of seashells in VFCW 1 was a differential factor (<i>p</i> < 0) for the removal of anionic surfactant (94.09 ± 7.77%), COD (88.43 ± 5.43%) and total phosphorus (45. 98 ± 9.86%) when compared to VFCW 2. The Langmuir isotherm was used to calculate the substrate adsorption capacity for total phosphorus, anionic surfactant, and COD. The results showed that adsorption on support materials was not the primary mechanism of pollutants removal. From 16S sequencing, it was observed that phylum Firmicutes was the most abundant (96.5%), followed by phylum Proteobacteria (3.5%). The results suggest that using seashells as an alternative substrate improved pollutant removal efficiency.