Bioadsorbents of heavy metals from coal mines area in Mozambique

Mozambique is one of the largest coal exporters in Africa. Usually miningactivities generate polluted water that is discharged into the Zambezi river basin in the Moatize area without treatment, increasing the risk both to the local environment and to public health because of this water containing significant amounts of metals and metalloids. At the same time, Mozambique is one of the largest producers of cassava peels, most of which are wasted. The aim of the present investigation was to study the use of discarded cassava peels to treat the polluted mine water from Moatize by means of adsorption. The effects both of the pH and of the contact time between the adsorbent, the adsorbate and the adsorption isotherms were examined.For calcium, magnesium, cobalt, mercury and manganese, an equilibrium wasattained in less than 50 min, the removal efficiency of calcium, magnesium, and mercury being greater under alkaline conditions and being greatest for cobalt at pH 4 and for manganese at pH 7.5. The correlation coefficients of the experimental data were very high for the calcium, magnesium and manganese metals as compared with the Langmuir and Freundlich isotherms. For the Langmuir isotherms, it was found that the adsorption of calcium, magnesium, cobalt, mercury, and manganese by the cassava peels was favorable for adsorption generally, whereas for the Freundlich isotherms it was only manganese that was found to be not favorable for adsorption

Water reclamation for industrial use in sub-Saharan Africa-A critical review

The increasing world population and growth of industrial development lead to growing water scarcity that, combined with deficient sanitation services, represents serious challenges, particularly in regions like sub-Saharan Africa. Water reclamation is a promising approach to reduce water scarcity, serving as a driving force for better sanitation services and protecting the environment by treating sewage and redistributing for the benefit of other water-dependent applications (e.g., industries). This paper aims to give an overview of the global trends on water reclamation, with a focus on industrial use, and to derive lessons for implementation of water reclamation projects in sub-Saharan Africa. Findings show that extensive experience exists in technology and management practices that can allow successful implementation of water reclamation projects in the region. Under the conditions of deficient sanitation services and low levels of technical expertise, the main challenge is to develop a framework that can facilitate the integration of social and technological methodologies and help in introducing water reclamation in water allocation planning, including the development of specific legislation for industrial water use and disposal.Sanitary Engineerin

Mitigation Potential of Sanitation Infrastructure on Groundwater Contamination by Nitrate in Maputo

In Maputo, the capital of Mozambique, nitrate concentrations above 250 mg L−1 in groundwater have been reported. This happens due to the widespread use of latrines and septic tanks that allow for constant infiltration of its content into the soil and eventually to groundwater sources, a situation that is widespread in the Global South and represents a serious threat for human health and for the environment. This is a reflection of limited access to safe and adequate sanitation services, which the local authorities have set to improve in the forthcoming decades with a recently commissioned city-wide sanitation masterplan serving as a basis for the works. In this article, we aimed at understanding whether the infrastructure projected in the masterplan would lead to a reduction of nitrogen reaching groundwater. Currently, according to our calculations, almost 500 tonnes of nitrogen reach the city’s groundwater sources each year, with the masterplan potentially resulting in a 14% reduction, a small reduction due to its reliance on maintaining and expanding fecal sludge services, without considering investments to improve domestic systems (e.g., construction of contained systems). An alternative, not presented in the Masterplan and put forward by the authors, could be the construction of simplified sewers in two of the city’s most densely populated neighborhoods, with a potential 29% reduction in nitrogen reaching groundwater