REUSE OF TREATED WASTEWATER (TWR) FOR SUSTAINABLE AGRICULTURE IN THE SAHEL: A BIBLIOGRAPHIC SYNTHESIS

In the face of an unprecedented global water crisis, exacerbated in the Sahelian zone by profound sanitation deficits, the reuse of treated wastewater (TWR) stands out as an indispensable circular-economy strategy for sustaining urban and peri-urban market gardening. This bibliographic synthesis examines TWR as an integrated value chain articulating effluent management, health safety, and agronomic sustainability. Technologically, the transition from conventional treatment to water suitable for raw horticultural irrigation requires advanced tertiary processes—membrane filtration, UV-C disinfection, or Nature-Based Solutions (NbS). These processes aim at the strict elimination of pathogens (bacteria, helminths) in compliance with WHO standards or EU Regulation 2020/741. Agronomically and economically, TWR provides a stable nutrient solution rich in nitrogen, phosphorus and potassium, enabling smallholders to reduce mineral fertiliser purchases by 40-60 % while increasing yields by 25-35 %. However, long-term viability depends on controlling critical risks: secondary soil salinisation, sodium-induced structural degradation, and bioaccumulation of toxic trace metal elements (TME) in the food chain. Finally, TWR deployment in the Sahel requires overcoming the disgust factor through transparent community approaches, formalising still-incomplete national legal frameworks, and favouring decentralised management models adapted to local socioeconomic capacities.