Stage temperature boosting in solar membrane distillation systems for agricultural wastewater treatment using waste heat recovery

Solar-powered membrane distillation for agricultural wastewater is limited by temperature polarisation and solar intermittency. This study evaluates stage temperature boosting – injecting low-grade agricultural waste heat at intermediate stages – in an eight-stage air-gap membrane distillation (AGMD) pilot operated at an agricultural research facility in the Fergana Valley (Uzbekistan). Under high irradiance (>800 W∙m−2), distillate flux increased by 88% from 6.5 ±0.4 to 12.2 ±0.6 kg∙m−2∙h−1 (n = 3, p < 0.001), and under low irradiance (99.5%; Escherichia coli not detected). By sustaining the thermal driving force and mitigating polarisation, stage temperature boosting couples solar input with site-available waste heat to deliver robust, energy- efficient water reclamation for agriculture.