Comparative performance of laterite and granite in the removal of organic pollution and nutrients by treatment of mixed wastewater from the city of Ouagadougou on hybrid planted filters of Canna generalis

Abstract

Comparative performance of laterite and granite in the removal of organic pollution and nutrients by treatment of
mixed wastewater from the city of Ouagadougou on hybrid planted filters of Canna generalis.
According to forecasts, Burkina Faso, which is in a situation of moderate water stress, will be in a situation of
permanent high water stress by 2030, exacerbated by pollution related to anthropic activities. The objective of this
work is to compare the performance of laterite and granite as culture media in the treatment of mixed wastewater
(EN) in the city of Ouagadougou. To do this, two hybrid filter systems, each composed of a vertical filter planted
with canna generalis connected in series with a horizontal filter not planted with laterite (SL) for one and granite
(SG) for the other, were fed at a rate of 260 L/m2/day for 3.5 successive days followed by a rest phase of the same
duration for several months. For the SL and SG systems respectively, the nitrate reductions are 98.76% and 96.92%
while those of orthophosphates, 90% and -5.76% indicate an enrichment in orthophosphates of the water from SG.
Concerning carbon pollution, the respective yields are 98% and 90.6% for BOD5. In sum, the granular support
made of laterite presents the best purification performances.