Environment
Lateef Bankole Adamolekun; Taiwo Blessing Olamide; Muyideen Alade Saliu; Esma Kahraman; Victor Afolabi Jebutu; Yewuhalashet Fissha; Adams Abiodun Akinlabi
Abstract
Examining the applicability of laterite clay for landfill and other engineering applications is critical due to the daily challenges that practitioners face as a result of material property variation. The suitability of seven selected laterite deposits in southwestern Nigeria as usable liner material ...
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Examining the applicability of laterite clay for landfill and other engineering applications is critical due to the daily challenges that practitioners face as a result of material property variation. The suitability of seven selected laterite deposits in southwestern Nigeria as usable liner material in solid waste landfill construction was investigated in this study, taking geotechnical properties and chemical composition into account. Purposive samples were collected and tested in accordance with ASTM standard procedures for analyzing geotechnical properties. X-ray diffraction analysis was used to determine the soil's clay mineral composition. The clay mineral composition of the soil was determined using X-ray diffraction analysis. The geotechnical analysis revealed the following ranges for the samples: gravel particle size percentage (3.7% to 34.0%), fines particle size percentage (17.4% to 71.7%), liquid limit (28.1% to 65.8%), plasticity index (3.95 to 45.53), activity (0.44 to 0.81), coefficient of permeability (6.75 x10-10 m/s to 5.80 x 10-6 m/s), specific gravity (2.639 to 2.768), and maximum dry density (1462 kg/m3 to 2065 kg/m3). X-ray diffraction test revealed that the clay minerals content in the seven location clay deposit varies depending on location. The study revealed that the clay mineralogical composition affects the suitability of the soil as a landfill liner material. Four among the seven clay deposits considered in this study were found suitable as a liner for solid waste landfills as compared with landfill material standard specifications.
M. Hosseini Nasab; M. Noaparast; H. Abdollahi
Abstract
In this research work, the bio-leaching of Co and Ni from an iron-rich laterite ore is assessed using the acidophilic heterotrophic (Delftia acidovorans)and autotrophic (Acidithiobacillus ferrooxidans) bacteria. The metabolic products of the acidophilic bacteria play an important role in bio-leaching. ...
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In this research work, the bio-leaching of Co and Ni from an iron-rich laterite ore is assessed using the acidophilic heterotrophic (Delftia acidovorans)and autotrophic (Acidithiobacillus ferrooxidans) bacteria. The metabolic products of the acidophilic bacteria play an important role in bio-leaching. The results obtained from the indirect bio-leaching indicate the highest nickel recoveries of up to 83.65% and 80.18%, respectively, by the supernatants of Acidithiobacillus ferrooxidans and Delftia acidovorans, both measured at 90 °C for 3 h with a stirring speed of 370 rpm and S/L of 0.1, while the corresponding cobalt recovery rates have reached 86.93% and 83.94%, respectively. The iron dissolution rates in these conditions for the two studied bacteria are 64.34% and 54.41%, respectively. The nickel and cobalt extractions by the indirect bio-leaching of Delftia acidovorans are, respectively, 29.84% and 23.75% higher than those for the direct bio-leaching, performed at 30 °C and 150 rpm of an incubator shaker for 30 days. For the indirect bio-leaching, the chemical control has a larger influence on the dissolution rate of the iron-rich laterite compared to the diffusion control. The activation energies of nickel and cobalt in the chemical control model are 40.07 and 39.08 kJ/mol, respectively.
