No abstract

The objective of this work is to study the contamination risks of market garden soils by metals using combustion debris (CD) as fertilizers. Therefore, two parcels of land usually used by farmer for market gardening have been rented on two sites. Soils were plowed, amended with CD and three plants species were grown. Samples of non-amended soils, amended soils and leaves of three species plants such as Amaranthus hybridus, Corchorus olitorius and Lactuca sativa were treated and then metals were analyzed by ICP-MS. The results obtained revealed the presence of several metallic elements such as Hg, Sn and Pb in soils with maximum concentrations of 15.03 ± 0.52, 6.16 ± 0.07 and 307.20 ± 16.30 mg/kg, respectively. The highest concentrations were found on amended soils. This means that a significant amount of metals found in amended soils would come from either direct or indirect CD. The same metals were identified in the leaves of three plants species, with concentrations which in some cases exceeded the recommended limit values. The L. sativa species is also one that has the most accumulation of Hg and Pb with average concentrations of 3.12 ± 1.18 and 3.1 ± 0.57 mg/kg, respectively, on the two sites. The results of the risk index also indicate the existence of a real risk of ingesting metals by consumers of vegetables grown on these soils.

No abstract

The treatment of slaughterhouse effluents is a problem for our municipalities and residents. The objective of this work is to contribute to the protection of the environment through a test treatment of the effluent from the slaughterhouse of cows by adsorption on adsorbents made from sawdust. To achieve this, two adsorbents were produced based on sawdust of Ayous (Triplochiton scleroxilon) and Iroko (Milicia excelsa), and were characterized. The effluent was sampled in a Ngaoundéré slaughterhouse and then characterized in its turn. Finally, discolouration tests by adsorption of this effluent were carried out. At the end of this work, it appears that both adsorbents produced had an acidic character. They are micro and macroporous with specific surface areas from 14.77 m2/g to 69.56 m2/g for Iroko and Ayous, respectively. The effluent from the slaughterhouse of cows sampled in the city of Ngaoundéré is highly conductive and turbid with an organic matter evaluated at 4.15 ± 0.18%. The adsorbent based on sawdust of Ayous is more effective, globally allowed the reduction of more than 70% of all the organic and inorganic loads of the slaughterhouse effluent after treatment. A discolouration rate estimated at more than 90% obtained at the scale of the laboratory, these adsorbents are effective for the treatment of the slaughterhouse effluents. These two adsorbents can therefore be used for the treatment of slaughterhouse effluent in any country in the world.