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

Abstract

Abstract: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 onnes 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.

Use of (partially) treated municipal wastewater in irrigated agriculture; potentials and constraints for sub-Saharan Africa

“…Water reclamation for irrigation in Maputo is performed unplanned in peri-urban areas. This practice is driven by water scarcity (Rietveld et al, 2016) and, likely, the availability of nutritional water (Agodzo et al, 2003;Huibers and van Lier, 2005), using the partially treated water from the nearby wastewater treatment plant in Maputo (Ars� enio et al, 2018;Tauzene et al, 2017). In addition, some examples of on-farm/on-site treatment can be found in Ghana and South Africa.…”

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

“…The resulting hot moist air is Table 3. Industrial water reclamation concern and potential treatment (sources: Asano, 1998;Cisneros, 2014;USEPA, 1992 released into the atmosphere, while the cooled water is collected into a reservoir at the bottom of the cooling tower, where it is returned into the recirculating system (Lens et al, 2002). In recirculating cooling systems, additional treatment, such as filtration, chemical precipitation, ion exchange or reverse osmosis, can be necessary to avoid scaling (Asano and Jiménez, 1998).…”

“…Furthermore, even the few existing central infrastructure systems in the region are generally not functioning at full capacity due to a lack of regular maintenance (Bahri et al, 2008). These very low levels of wastewater treatment have high negative impacts on receiving water bodies (Arsénio et al, 2018;Eckart et al, 2011) and on the health of the urban populations (Duflo et al, 2012).…”

Water Reclamation for industrial use in sub-Saharan Africa, a Critical Review

“…Furthermore, even the few existing central infrastructure systems in the region are generally not functioning at full capacity due to lack of regular maintenance (Bahri et al, 2008). These very low levels of wastewater treatment have high negative impacts on receiving water bodies (Arsénio et al, 2018;Eckart et al, 2011) and on the health of the urban populations (Duflo et al, 2012).…”