A solar energy-powered system to drive tertiary treatment in wastewater treatment plants is being advanced by researchers from the Universidad de Jaén, Spain. The Open SolWat technology integrates photovoltaic (PV) modules and water disinfection reactors.

The technology harnesses ultraviolet (UV) and far infrared radiation to disinfect water, while visible and near-infrared radiation are tapped to generate electricity through the PV module. A 1 mm thin film of water flows over the module by means of a pumping system. The water is spread across the front side of the panel and is then collected in an external water tank made of aluminum L-profiles, with a funnel transferring the water to the tank. The tank is exposed to solar radiation and functions as a solar water disinfection reactor.

Two prototypes were tested with wastewater treatment plant samples on the roof of a building in Linares, Spain. The larger version used a 45 W module, two water reactors and a magnetic coupling water pump with an average flow rate of 8.9 L/m. The smaller system uses a module with a nominal power of 5 W.

The larger setup had a radiation exposure of around 95% to 97%, whereas the smaller one had only 2.8% exposure because it lacked an external, fully exposed water tank. As reported in the Journal of Water Process Engineering, water quality results from the larger prototype met Spanish and European regulations, making it suitable for urban, agricultural, industrial and environmental purposes.

The smaller system showed energy losses of up to 2.89% compared to a reference system without cooling, due to partial shading from the system itself. The larger system improved electricity generation by 15% to 21%.

The researchers concluded that the energy generated could be used to power the SolWat pumping system and meet other energy needs at a wastewater treatment plant. Future efforts will focus on scaling up the system to a larger prototype and optimizing this technology using low water consumption pumps.