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First-row transition metals (Co, Ni, Cu and Zn) were successfully used in the preparation of activated carbons from wood biomass via microwave-assisted irradiation. Physical-chemical properties of the produced materials (MWAC) were studied by nitrogen adsorption-desorption curves, SEM, FTIR, UV-vis DRS and synchronous fluorescence spectroscopy, CHN elemental analysis, TGA/DTG, pH, hydrophobic properties, and total acidity and basicity groups. Results showed that the metals were bound successfully in different amounts with surface functional groups of the wood biomass through ion exchange and surface complexation interaction during the impregnation step. Zn and Cu formed the most complexes. MWAC impregnated with Zn showed higher pore volumes and surface areas, followed by Cu, Co and Ni, independently of the ratio used. As the metal : biomass ratio was increased from 0.5 to 2, the surface area of MWAC increased from 300 to 620mg for Co-MC, 260 to 381mg for Ni-MC, 449 to 765mg for Cu-MC and from 572 to 1780mg for Zn-MC. The samples showed high values of carbon contents and oxygen-containing groups. An adsorption experiment revealed that samples prepared using ZnCl showed the highest sorption capacities (q) for the tested adsorbates, followed by CuCl, CoCl and NiCl. These results matched with the surface areas and pore volumes trends, which were found to follow atomic number and melting point trends-Ni(II)bisphenol A>hydroquinone>4-nitro phenol>2-naphtol>paracetamol>caffeine>resorcinol.

A preliminary insight into metal cycling within the urban sewer was obtained by determining both the heavy metal concentrations (Cu, Zn, Pb, Cd, Ni, Cr) in sewage and sediments, and the nature of metal-bearing particles using TEM-EDX, SEM-EDX and XRD. Particles collected from tap water, sump-pit deposits, and washbasin siphons, were also examined to trace back the origin of some mineral species. The results show that the total levels in Cu, Pb, Zn, Ni, and Cr in sewage are similar to that reported in the literature, thus suggesting that a time-averaged heavy metal fingerprint of domestic sewage can be defined for most developed cities at the urban catchment scale. Household activities represent the main source of Zn and Pb, the water supply system is a significant source of Cu, and in our case, groundwater infiltration in the sewer system provides a supplementary source of Ni and Cd. Concentrations in heavy metals were much higher in sewer sediments than in sewage suspended solids, the enrichment being due to the preferential settling of metal-bearing particles of high density and/or the precipitation of neoformed mineral phases. TEM and SEM-EDX analyses indicated that suspended solids, biofilms, and sewer sediments contained similar heavy metal-bearing particles including alloys and metal fragments, oxidized metals and sulfides. Copper fragments, metal carbonates (Cu, Zn, Pb), and oxidized soldering materials are released from the erosion of domestic plumbing, whereas the precipitation of sulfides and the sulfurization of metal phases occur primarily within the household connections to the sewer trunk. Close examination of sulfide phases also revealed in most cases a complex growth history recorded in the texture of particles, which likely reflects changes in physicochemical conditions associated with successive resuspension and settling of particles within the sewer system.

Unsafe drinking water is one of the main concerns in developing countries. In order to deal with this problem, a cooperation project was set up by the ACRA Foundation in the Logone valley (Chad-Cameroon). Water supplies were sampled throughout the villages of this area mostly from boreholes, open wells, rivers and lakes as well as some piped waters. The samples were analysed for their physical-chemical and microbiological quality in order to identify the contamination problems and suggest appropriate solutions. Results of the assessment confirmed that in the studied area there are several parameters of health and aesthetic concern. Elevated lead levels were detected both in aquifers and in surface waters, confirming that further investigations of the occurrence of lead contamination in the Logone valley are warranted. In addition, many groundwater sources are negatively impacted by parameters of aesthetic concern, such as turbidity, iron and manganese. Even though they do not affect human health, elevated levels of these parameters cause consumers to abandon improved water supplies, often in favour of surface water sources that are microbiologically contaminated. The use of alternative sources, improvement of water supply structures and water treatment are possible solutions to improve the quality of drinking water in the Logone valley.

Activated carbon (AC) was prepared from sapelli wood sawdust using a microwave heating process. The biomass was mixed with inorganic components (lime ? ZnCl 2 and FeCl 3) to form a homogeneous paste. The AC samples are denoted as AC-1A (100 g sapelli wood sawdust ? 20 g lime ? 80 g ZnCl 2), AC-2A (150 g sapelli wood sawdust ? 20 g lime ? 80 g ZnCl 2), AC-1B (100 g sapelli wood sawdust ? 20 g lime ? 40 g ZnCl 2 ? 40 g FeCl 3), and AC-2B (150 g sapelli wood sawdust ? 20 g lime ? 40 g ZnCl 2 ? 40 g FeCl 3). The samples were placed in a microwave oven and pyrolyzed under nitrogen flow. To increase their porosity, the pyrolyzed samples were subjected to a leaching process (with 6 mol L-1 HCl) under reflux to eliminate inorganic components. Several analytical techniques such as Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and N 2 isotherm and vapor adsorption analyses were performed to characterize the AC materials. The samples presented high Brunauer-Electronic supplementary material The online version of this article (