This paper describes artisanal gold mining practices and environmental impacts around the Ity-Floleu gold mine, in western Côte d'Ivoire. Interviews and field observations as well as measurements of turbidity and water flow velocity in the section of the river (Cavally) watering the study area, made it possible to identify 13 artisanal mining sites, housing 247 artisans, operating in groups made up mainly of 5 to 10 people. The activity is dominated by local populations from the villages of Ity and Floleu and the surrounding communities. Gold mined comes from alluvial and vein ores, with a predominance of alluvial ore, extracted in the sediments of the bed and the banks of the river and in the soils, inside forests. In the bed of the river, sediments are dredged using machines placed on boats, from where they are washed in mats and then dumped into the watercourse. On the other hand, on the banks of the river and in the forests, the material used consists of picks, dabas, mats, and shovels. In all cases, gold is recovered as a concentrate of gold powder. As regards vein ores, they are also extracted along with the soils of cultivable land, but in the form of blocks of stone which are crushed and washed. The gold is then recovered using mercury, followed by cyanidation. The techniques used lead to the silting up and the fall of the banks of the river, reduction of agricultural land, and the degradation of the environment by the tailings. The Cavally River appears to be strongly impacted in the midstream part of the Ity-Floleu axis, marked by a decrease in the bed and the river flow velocity (0.19 m/s) and higher turbidity (255.3 NTU). More effective policies are urgently needed to restore degraded ecosystems, both aquatic and terrestrial.

The majority of population growth in developing countries will occur in secondary cities where there is limited access to clean water and sanitation. Wastewater management priorities in these cities will be different from those in larger cities and developed countries. For this reason, it is important to assess wastewater management in these cities of sub-Saharan Africa. This study assessed clean water supply, wastewater and faecal sludge management and associated health risks in Dimbokro, Côte D'Ivoire. The study was performed in March 2015 in 12 neighborhoods with a total of 703 households. In these neighborhoods, the questions were addressed and discussed with household head. The study revealed that the households of the city were structured on three topology habitats: residential (5%), economic (42%) and evolutive or yards housing (53%). For water supply, 99.4% of the households used water from SODECI, the local public water supply network, while the remaining 0.6% of surveyed household obtained water from wells. Domestic wastewater, used for doing laundry, dishwashing and showering, was disposed of in the following ways: directly into the street (33%), septic tank (23%), backyards (18%), storm drain (16%), sewer network (6%), pit latrine (3%) or into soakaway (2%). In addition, untreated wastewater was sometimes discharged into the N'Ziriver by certain households. 52% of households surveyed emptied latrines manually and 48 % used mechanic drain services. The most frequent diseases occurring in the households were Malaria (63%), Diarrhoea (13%) and Typhoid fever (9%) in the households of the city. In the light of this study, the municipal authorities of Dimbokro should provide the city with wastewater systems that drain to a central outlet system where the wastewater can be easily treated before final disposal for reuse in agriculture.

Organic compounds such as humic substances in the natural environment, especially in aquatic environments, are source of environmental problems. The stability of humic compounds in the soil is due to their adsorption on colloid surfaces through reactions with cations to form organ- mineral complexes. Many parameters such as pH, ionic strength. can affect the adsorption of humic substance on mineral surfaces. This study was initiated to investigate the use of a natural geo-material such as laterite for recovery and environmental application through batch adsorption tests. Since this system is a closed and agitated system, it makes it possible to obtain the maximum conditions for adsorption. Lateritic soil are abundant in tropical soil and exhibits some specificities that could promote humic acids-soil interactions. So, the analysis of pH influence on humic acid-laterite interactions is monitores through batch adsorption tests of a commercial humic acid at different pH (4.5; 6.5 and 8.5). The adsorption kinetic yield (R) is followed at each pH. Prior to the adsoption test, the raw laterite was analysed using infrared spectroscopy. The results of the kinetics of humic acid adsorption yield at different pH (4.5; 6.5 and 8.5) showed that the adsorption yield was inversely proportional to the increase of pH. The highest yield is obtained at pH 4.5 (94.56 %). Infrared analyzes of the laterite before and after adsorption shows that the surface of the laterite has undergone modifications associated to humic acid presence in the complexe after adsorption test. However, the media most affected by adsorption were observed at pH 8.5 and pH 4.5. The changes observed are due to the interactions between the aluminum oxides of gibbsite-AH (Al(OH)2–O–R) and kaolinite-AH (Si2O5Al2(OH)3–OH–R present on the surface of materials and the bonds of carboxylic, aromatic, phenolic, etc. groups confirms the adsorption reaction between humic acid and laterite.

Mineralization of gaseous chlorobenzene (major VOC from cement plants) was studied in a continuous reactor using three advanced oxidation processes: (i) photocatalysis, (ii) Dielectric Barrier Discharge (DBD) plasma and (iii) DBD/TiO2-UV coupling. The work showed an overproduction of OH * and O * radicals in the reaction medium due to the interaction of Cl * and O3. A parametric study was carried out in order to determine the evolution of the removal efficiency as a function of the concentration, the flow rate and the applied voltage. Indeed, a variation of the flow rate from 0.25 to 1 m3/h resulted in a decrease in the degradation rate from 18 to 9%. Similarly, an increase in concentration from 13 to 100 mg/m3 resulted in a change in degradation rate from 18 to 4%. When the voltage was doubled from 6 to 12 kV, the degradation rate varied from 22 to 29 % (plasma) and from 53 to 75% (coupling) at 13 mg/m3. The evolution of COX and O3 was monitored during the experiments. When the voltage was doubled, the selectivity increased from 28 to 37% in the plasma alone and from 48 to 62 % in the coupled process. In addition, at this same voltage range, the amount of ozone formed varied from 10 to 66 ppm in plasma and 3 to 29 ppm in coupling. This degradation performance can be linked to a synergistic effect, which resulted in an increase in the intensity of the electric field of plasma by the TiO2 and the improvement in the performance of the catalyst following the bombardment of various high-energy particles of the plasma.

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