Circular Water, Energy, and Food Nexus: Wastewater Reuse and Biomass Energy for Climate-Resilient Agriculture in Burkina Faso

Burkina Faso faces three converging pressures on its agricultural sector: rainfall variability, structural water scarcity, and a chronic energy deficit that limits irrigation and post-harvest processing. At the same time, large volumes of municipal wastewater are discharged with little or no treatment, and an estimated eight million tonnes of agricultural residues are produced annually, most of which is burned or left to decompose. This paper develops a circular Water, Energy, and Food (WEF) nexus framework for Burkina Faso that couples wastewater reuse in peri-urban agriculture with biomass energy recovery from crop residues. We combine Material Flow Analysis (MFA), a screening-level Life Cycle Assessment (LCA), four-scenario simulation (baseline, water reuse only, biomass only, and full circular integration) calibrated on a synthetic but literature-constrained parameter set representing plausible Burkinabè operating conditions for the period 2005 to 2024, and an exploratory STIRPAT (Stochastic Impacts by Regression on Population, Affluence and Technology)-type elasticity analysis. We also propose a composite Nexus Efficiency Index (NEI) to compare scenarios on a common scale, and report Monte Carlo uncertainty propagation across the parameter ranges. Every quantitative result reported here is a simulated output from a literature-constrained synthetic dataset rather than an empirical estimate for Burkina Faso. Under the central parameter assumptions, the integrated circular scenario was associated with modelled reductions in freshwater abstraction of approximately 25 to 40 percent, modelled yield gains of 20 to 40 percent, and modelled reductions in CO₂-equivalent emissions of 30 to 45 percent at the farm gate relative to the linear baseline. The mobilizable biomass potential of cotton stalks and rice husks, estimated independently at around 44,891 tonnes of oil equivalent per year, would cover a meaningful share of irrigation pumping and agro-processing demand. An indicative economic feasibility check, drawing on published CAPEX and OPEX ranges for constructed wetlands, small biogas digesters, and small-scale gasifiers, suggests payback periods in the order of 5 to 10 years for representative peri-urban configurations. The findings suggest that decentralized treatment-and-reuse infrastructure paired with small-scale biogas and gasification systems may represent a promising pathway supported by nexus-aware regulation. The originality of the contribution lies in integrating Material Flow Analysis,