Adriana Aparecida dos Santos, Augusto Cesar Laviola de Oliveira, Natália dos Santos Renato, Raphael Bragança Alves Fernandes, Fernando França da Cunha, André Pereira Rosa, Alisson Carraro Borges
The use of treated wastewater constitutes a strategic alternative for agriculture in water-scarce regions. This study developed and applied a distance-based and sodium-constrained deterministic allocation model integrating geoprocessing tools with environmental and logistical constraints to optimize the spatial distribution of treated effluent from 48 wastewater treatment plants (WWTPs) in the semi-arid region of Minas Gerais, Brazil. The deterministic allocation algorithm prioritizes geographic proximity and favorable topographic differences as a proxy for reducing potential pumping requirements. Two scenarios were evaluated: (1) full effluent availability and (2) sodium-regulated allocation limited to 300 kg ha−1 year−1 of Na, in accordance with Normative Deliberation CERH-MG 65/2020. Under Scenario 1, cotton demand exceeded (184%), while coffee and sugarcane reached 69% and 24% of annual demand, respectively. Under the sodium-constrained Scenario 2, demand fulfillment changed to 37% for coffee and 42% for sugarcane, while cotton remained above full demand (108%). The proposed model differs from previous deterministic spatial allocation applications by integrating regulatory sodium constraints and dual-scenario regional assessment, providing a spatially explicit and regulation-compliant decision-support tool for sustainable wastewater reuse in semi-arid agricultural systems.