The objective of this study was to know the effect of particle size of the laterite contained in reactors filled with laterite and sand on the removal of the physicochemical parameters of a well water. Three reactors filled from the bottom to the top with 10 cm of granitic gravel, 50 cm of sand, 10 cm of standing water and 30 cm of different particles sizes of laterite (granular, very coarse and medium) were used. The depths of the sand and the standing water were fixed according to a previous study. pH, conductivity, turbidity, suspended solids, ammonium, nitrate, lead and total iron were analyzed according to standard norms. The results showed that pH increased with decreasing particle size while conductivity decreased. With regard to suspended solids and turbidity, the removal was (98.9%) and of the same order in all the reactors. Removal efficiency of ammonium ranged from 97.67% to 98.1% in the reactors. The reactors also removed nitrate, total iron and lead. In addition, the concentrations of nitrate, total iron and lead decreased with increasing particle size. However, the reactor filled with medium laterite and sand was the most efficient.

The kaolinite-coating laterite (B catalysts) was used for the efficient degradation of methylene blue (MB) from aqueous solution. Heterogeneous Fenton catalytic oxidation experiments of B catalyst were investigated by changing the effective factors such as amount of laterite and amount of kaolinite. To that end, four (4) types of B catalysts were made: (i) B0 catalyst (50% kaolinite + 50% uncalcined laterite); B1 catalyst (50% kaolinite + 50% laterite calcined at 600°C), B2 catalyst (30% kaolinite + 70 % laterite calcined at 600° C) and B3 catalyst (100 % kaolinite + Iron solution from laterite). The result showed that B2 catalyst exhibits the highest performance with a MB degradation percentage (77%) after 100 min. For analyzing the performance of B2 catalyst, the effects of B2 catalyst amount, pH, and hydrogen peroxide (H2O2) were also studied at 100 min. Kinetic studies were also carried out in this experiment. The results indicated that more than 90% of decolorization was achieved with 60g of B2 catalyst at pH acidic (2 to 3). Moreover, higher MB degradation (≤ 90%) was reported at the presence of H2O2 and B2 catalyst in the reactor. However, only 14% of MB was adsorbed in the presence of H2O2 and without B2 catalyst. On the other hand, it was observed that second- order kinetics (R2>0.90) was well fitted in the MB degradation process. Considering the above, kaolinite-coating laterite (B2 catalyst) could be used as efficient, cheap, and eco-friendly catalytic oxidation material for the degradation of MB in aqueous solution.

Plant density may have an influence on constructed wetlands (CWs) operation. In this study, the effect of plant density on the efficiency of vertical-flow CWs planted with Panicum maximum treating domestic wastewater was investigated. Two beds were planted with P. maximum at 10 plants/m2 (low density) and two others at 20 plants/m2 (high density). Two unplanted beds were used as control. During six months, domestic (0.05m3) raw wastewater was applied on each bed intermittently. Wastewater samples were taken once a week into the influent and the filtrate of each bed and preserved at 4°C until analysis. The results showed that pollutants were significantly more removed in the planted beds than in the controls. But, the plant densities used were not significantly impact the treatment efficiency. However, the bed planted at low density was clearly distinguished as the one that provided the higher pollutants removal rates (TSS = 91.8%, DCO = 91.6%, P = 69%, PO43- = 74.9%, NTK = 86.5%, NH4+ = 86.5%, Escherichia coli = 87.1%, Clostridium perfringens = 96.7%).

Sanitation and health of populations regarding malaria and diarrhea syndromes were studied in precarious neighborhoods of Abobo (Abidjan, Côte d’Ivoire). Globally, 587 concessions were sampled with 14 232 people. Human excreta are essentially disposed in autonomous sanitation systems (8-88%). The grouping of neighborhoods according to their sanitation gave three entities: (Anonkoua and Abobo PK-18) (Sagbé, Avocatier, M'Ponon and Jean-Tahi) and (Abobo-Baoulé). People have access to the drinking water from SODECI for various usages depending on the use and the season. Drinking water from SODECI is the only one used in the dry season, but it’s partially substituted by rainwater during the rainy season for bath, clothes washing and dishes. However, it is exclusively used for drinking regardless of the season. The classification of precarious neighborhoods based on water use gives five groups: (Anonkoua, Avocatier) (Sagbé, Abobo PK-18), (Jean-Tahi) (M'Ponon) and (Abobo-Baoulé). Population health in these areas is worrying with 47% of patients (35% of malaria syndrome cases and 12% of diarrhea syndrome cases). The young population ([0-8 years [) is the most affected, with 25% of malaria syndrome cases and 34% of diarrhea syndrome cases.

Pesticides used for intensive agricultural production threaten natural resources and human health. The aim of this study is to analyze the use of pesticides in the Marahou

Four biosand filters were used for treatment of Banco river source water to investigate the effects of sand depth (30, 50, 70 and 90 cm) on the removal of suspended solids, nitrogen and oxidized forms of the chemical demand oxygen and their effect on the pH. The results showed that the filter of 90 cm of sand was the most efficient. However, the purification yields between filters 50, 70 and 90 cm of sand showed no significant difference, and the treated water met the drinking water standards of the world health organization. Therefore, sand depth between 50 and 90 cm can be used in biosand filter to treat water.