Study of the Biomass of Macrophytes Presumed to Be Phytopurators in Wastewater Treatment in Brazzaville (Republic of Congo)

The aim of this work is to study the biomass of macrophytes during the wastewater phytoremediation process. To do this, a physicochemical characterization of these waters, including temperature, pH, EC, COD, NH<sub>4</sub><sup>+</sup>, NO<sub>3</sub><sup>-</sup>, and PO<sub>4</sub><sup>3-</sup> was carried out and first revealed the very high concentrations. Then, a treatment was done with two types of macrophytes (<i>Echinochloa pyramidalis</i> (Lam) Hutch and <i>Cyperus Alternifolius</i> L) which showed a significant reduction in these physicochemical parameters at the exit of the basins. When comparing the two treatment ponds, the <i>Echinochloa pyramidalis</i> pond performed better on the removal of pollutants from wastewater than the <i>Cyperus Alternifolius</i> pond. Finally, the study of the growth of these two types of macrophytes showed that <i>Echinochloa pyramidalis</i> grows faster than <i>Cyperus Alternifolius</i> and is almost double that of the latter. This study shows that the two macrophytes cannot be together in a filter to treat wastewater because the biomass of Echinochloa pyramidalis (Lam) Hutch is higher than that of Cyperus Alternifolius L and the two will compete against each other, Echinochloa pyramidalis (Lam) Hutch will hinder the growth of Cyperus Alternifolius L and lead to the gradual disappearance of the latter and this competition makes the macrophyte inefficient that seeks to defend its territory and gain space instead of eliminating pollutants.