Sustainable hydroponic production using solar energy and treated greywater within the water-energy-food-environment nexus

Addressing the Water-Energy-Food-Environment (WEFE) nexus is critical for sustainable resource management. This study investigates a novel hydroponic system integrating photovoltaic (PV) solar energy and treated greywater (System-II), compared to a grid-powered system (System-I). Key performance indicators, including energy consumption, energy efficiency indices, and CO₂ emissions, are evaluated for the two systems. Additionally, the morphological, physiological, and biochemical parameters of lettuce are measured. System-II achieved superior energy performance, with an energy ratio of 0.11, energy productivity of 0.16 kg/MJ, and specific energy of 6.14 MJ/kg, compared to System-I's 0.05, 0.07 kg/MJ, and 14.89 MJ/kg, respectively. Additionally, the water use efficiency values were 0.071 kg/L for System-I and 0.073 kg/L for System-II. Moreover, System-II reduced CO₂ emissions by over 94%, emitting only 0.0861 kg CO₂ eq/m², compared to 1.5386 kg CO₂ eq/m² from System-I. Morphological and physiological traits of lettuce irrigated with treated greywater remained optimal, showing a mean head weight of 682.9 g, head length and diameter of 17.7 cm and 18.3 cm, relative water content of 93.5%, 5.4% dry matter, and total chlorophyll content of 1.023 mg/g, comparable to those irrigated with tap water. This study highlights the potential of solar-powered hydroponics, utilizing treated greywater as a scalable and sustainable solution for efficient food production in alignment with WEFE nexus objectives. The findings provide insights into optimizing resource management in agricultural systems and contribute to the development of resilient, efficient, and sustainable food production systems in the face of global resource challenges.