Heavy Metal Remediation in AgoèNyivéLandfill Soils: Enhancing Stability through Organic Amendments

The burial of waste in developing countries, which is often carried out without respect for environmental standards, constitutes a risk of contamination of soils and even groundwater given the toxic elements they contain. The objective of this work is to carry out a study of the retention of heavy metals through the contribution of cattle manure to soil samples from the final Agoè Nyivé landfill in Lomé, Togo. Soil samples from the final landfill were taken from the surface and depth at several locations to form a composite sample. The amendment of the composite sample was carried out with bovine manure on the mock-up in the Laboratory for six months. The determination of the total contents of heavy metals by the atomic absorption spectrophotometer (SAA) on the composite sample showed high contents exceeding the thresholds recommended by the AFNOR NF U 44-041 standard. Sequential extraction on these composite samples showed that the mobile portions of lead, cadmium, copper and zinc are respectively estimated at 78.06%, 50%, 28.89% and 91.59%. The bovine manure used to amend the landfill samples presents physicochemical parameters that can contribute to rendering heavy metals immobile in the soil matrix under natural conditions. The addition of manure initially made it possible to increase the values of pH, electrical conductivity, cation exchange capacity and organic matter, which promote the retention of heavy metals. Secondly, the addition of manure made it possible to reduce the mobile portion of the heavy metals studied;from 78.06% to 14.39% for lead, from 50% to 11.52% for cadmium, from 28.89% to almost 0% for copper and from 91.15% to 80.58% for zinc. The use of cattle manure as an amendment on the composite sample was decisive in reducing the mobility of heavy metals in the polluted soils of the final landfill.

Determination of Pesticide Residues in Soils of Cotton Farming Areas in Togo

The main cash crop in Togo is cotton, with about 70% of agricultural exports. This crop is very dependent on the use of chemical inputs, in particular pesticides. Pesticides used in cotton farming in Togo include organochlorines, triazines, organophosphates and pyrethroids. We conducted a study on the impact of these pesticide use, in particular organochlorines and triazines, on cotton farming soils. We chose the Plateaux region (southern Togo) as the study area because of its high cotton production. Analysis was carried out on crop soil samples at the 0 - 20 cm horizon. Several pesticide residues were found: simazine (0.051 to 0.103 μg/Kg soil);atrazine (0.149 to 0.197 μg/Kg soil);lindane (0.259 to 0.672 μg/Kg soil);β-endosulfan (1.37 to 5.727 μg/Kg soil);dieldrin (0.063 to 1.16 μg/Kg soil);endrin (0.512 μg/Kg soil), Heptachlor (0.489 to 1.243 μg/Kg soil);Heptachlor epoxide (0.928 to 1.633 μg/Kg soil);[2,4'DDT] (0.257 μg/Kg soil);[4,4'DDE] (0.262 μg/Kg soil). These results show pesticide contamination of cotton farming soils.

Physico-Chemical and Mineralogical Characterizations of Two Togolese Clays for Geopolymer Synthesis

Geopolymers are an alternative to Portland cement, well known for their contribution to greenhouse gas emissions. Finding materials that can validly replace Portland cement is a challenge. It is in this logic that this work was undertaken with the objective of characterizing two local clay resources of Togo as raw materials for geopolymers. The physico-chemical properties of these clays were determined by characterization using X-ray diffraction (XRD), Fourier transform infrared (FTIR), thermogravimetric (TGA) and elemental analysis (ICP-OES). The results show that these clays contain kaolinite and therefore can be used in the formulation of geopolymers. The characterized clays underwent heat treatments transforming the crystalline phases into more reactive amorphous phases and then were activated by an alkaline solution in order to formulate the geopolymer materials. These elaborated materials were analyzed by Fourier transform infrared to identify the types of bonds formed. The results of these analyses show that these two local clays are well suited to be used in synthesizing geopolymers. Our future work will focus on the constraints of consolidation as well as the mechanical properties of these geopolymer materials.

Physicochemical and Mineralogical Characterizations of Wastes Coming from Phosphate Ore Processing of Hahotoéand KpogaméMines

In the framework of various phosphates discharges valorization, we have realized physicochemical and mineralogical characterizations of these discharges. We have undertaken the physicochemical and mineralogical characterizations of this waste by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), thermal analysis and Atomic Emission Spectrometry Coupled to an Inductive Plasma Source. The results of these analyze show that phosphate sludge and screen rejects could be used in ceramics, in the manufacture of aggregates, in agriculture and other fields. On the other hand, rich magnetic waste could be used in heterogeneous photocatalysis in waste liquids treatment.

The Use of Clay as a Methane Emission Mitigating Feed Additive in DjallonkéRams

Four groups each composed of six rams with 15 kg average body weight were submitted to one of the following diet: Panicum maximum C1 (PM), Panicum maximum C1 plus concentrate (PM_Co), Panicum m. C1 plus clay (PM_Ar ) and Panicum maximum C1 plus concentrate plus clay (PM_Co_Ar). The concentrate is composed of 90% weat bran, 9.25% cottonseed cake, 0.5% premix and 0.25 cooking salt. The clay used was a mixture of 59% smectite, 14% kaolinite and 27% quartz. The significance of treatments on variation in physico-chemical characteristics (ruminal pH and concentration of ammonia nitrogen), as well as in the rumen fermentation profile i.e. Volatile Fatty Acid concentration and in the enteric methane (CH4) production, depending on the rumen fluid collection time (at 9 o’clock and 13 o’clock), were studied using AOV. The highest ruminal pH was recorded in animals fed the mixture of Panicum plus clay, which is 7.02 ± 0.12 against 6.96 ± 0.12, 6.8 ± 0.06 and 6.69 ± 0.15, respectively in animals fed with PM, PM_Co and PM_Co_Ar. Incorporation of clay in the mixture of Panicum C1 plus concentrate had a stabilizing effect on ruminal pH. A significant decrease in the concentration of ruminal N-NH3 was recorded with PM_Ar (56.6 ± 15.2 g/ml), compared to PM (89.0 ± 18.9 g/ml). However, the ruminal N-NH3 concentration of animals fed the PM_Co diet (71.0 ± 15.1g /ml) increased in comparison to that of the PM_Co_Ar diet fed animals. Compared to the enteric methane concentration of the PM ration fed animals, the decrease of CH4 concentration was 2% - 5%, 7% - 11% and 19% - 23% respectively in the PM_Ar, the PM_Co and the PM_Co_Ar diets fed rams. These results suggest that the methane reducing effect of clay might be emphasized by the concentrate supplementation of the diet.