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Spanish researchers have developed a new system that simultaneously produces photovoltaic energy and disinfects wastewater.
Researchers from the University of Jaén have developed a novel technology for the disinfection of wastewater and the production of photovoltaic energy.
The Open SoWat system is designed for tertiary treatment, the third and final process in wastewater treatment plants (WWTP). It is an improvement of SolWat technology, which consists of a photochemical technology that integrates photovoltaic modules and water disinfection reactors.
“To extend the system to commercial use, it is necessary to conduct preliminary experimental studies using a full-scale prototype. Optimizing this technology will involve the use of energy-efficient water pumps. In addition, a study of its energy consumption and an economic analysis of the system will be carried out,” researcher J. Torres told pv magazine .
According to the research group, the technology takes advantage of various wavelengths of solar radiation for different purposes. It uses ultraviolet (UV) and far infrared (FIR) radiation to disinfect water, significantly reducing the presence of harmful microorganisms. Additionally, visible (VIS) and near-infrared (NIR) radiation is used to generate electricity through the photovoltaic module.
The Open SolWat system works dynamically with water recirculation to reduce the operating temperature of the solar module. It consists of a photovoltaic module over which a thin 1 mm film of water flows thanks to a pumping system. The water spreads across the front face of the panel and is then collected in an external water tank made of aluminum L-profiles, with a funnel that transfers the water to the tank.
“The tank is exposed to solar radiation and functions as a solar water disinfection reactor,” explain the scientists, who point out that in the classic closed configuration of SolWat, a thin 18 mm film of waste water is applied to the photovoltaic module. , closed with borosilicate glass.
To test the feasibility of the system, scientists have built two prototypes: the small open SolWat system and the large open SolWat system.
“The first reactor consisted only of an L-shaped aluminum profile at the top of the photovoltaic module, which was equipped with a perforated tube with 53 microtubes for the water outlet, spaced 1 cm apart,” they explained. “The second reactor was an open, translucent water tank measuring 62 cm x 45 cm x 18 cm.”
The largest prototype uses a 45 W module from the British manufacturer PV Logic, two water reactors and a magnetically coupled water pump with an average flow rate of 8.9 L/m manufactured by the German company Flojet Corporation. The smallest system uses a module with a power rating of 5 W.
After building the prototypes, the researchers placed them on a roof in the Spanish municipality of Linares and carried out a series of experiments. These included physicochemical and microbiological analyses, as well as electrical performance.
“The Linares WWTP provided the experimental samples, which were obtained directly after secondary treatment, which means that it is not water prepared in the laboratory, but rather natural water with organic matter,” the scientists explain. “Representative samples were always collected between 9:00 and 10:00 on the day of each experiment. The experiments were started around 11:00-12:00 pm local time, 2-3 hours before solar noon.”
The largest setup had a radiation exposure of between 95% and 97%, while the smallest had only a 2.8% exposure because it lacked a fully exposed external water tank. The water quality results of the largest prototype complied with Spanish and European regulations, making it suitable for urban, agricultural, industrial and environmental uses.
The smallest configuration showed power losses of up to 2.89% compared to an uncooled reference system, due to partial shading of the system itself. However, in the case of the largest installation, the system improved electricity generation by 15% to 21%. However, the researchers concluded that it did not significantly affect the final energy production of the classic SolWat reactors.
“The energy generated could be used to power the SolWat pumping system and meet other energy needs in a wastewater treatment plant,” the researchers concluded. "To achieve this in future research, we intend to scale the system to a larger prototype and optimize this technology using low water consumption pumps, as well as carry out a study of its energy consumption."
The researchers presented the system in “ SolWat technology for simultaneous wastewater disinfection and higher energy generation utilizing PV module front surface ,” recently published in the Journal of Water Process Engineering .
“This research highlighted the large-aperture SolWat system with the most optimal results of SolWat technology to date, both for solar water disinfection and for simultaneous energy production,” said Torres. |
