Solar-powered wastewater treatment: Integrating pumped storage and hydroelectric generation for autonomous operation

The transition to decentralized renewable energy systems faces challenges from the temporal availability and gaps of various sources. This study addresses this issue by designing a hybrid off-grid system for the Ariel University Dormitory WWTP, a 500 m³ /day biofilter facility. The system integrates solar energy, pumped storage, and hydroelectric generation while enabling reclaimed water use for gravity-fed irrigation. After optimizing the operational algorithm, the system functions autonomously most of the year. However, insufficient solar insolation during January-February prevents adequate pumping to hydraulic storage, which suggests that another source of renewable energy, such as wind or biomass-based, should be added to the solar array. The research demonstrates the feasibility of small-scale hybrid renewable systems for autonomous critical infrastructure while identifying seasonal limitations. The particular application for a biofilter-type WWTP has proved successful as it can endure several hours with no energy supply.