Assessment of a pilot solar V-trough reactor for solar water disinfection

Abstract

Rural and isolated communities of low-income countries suffer the lack of access to safe drinking water. Harvested rainwater (HRW) is becoming an alternative source of freshwater in many areas of the world. Nevertheless, its quality usually doesn’t meet drinking water standards, posing a health risk for human consumption. Solar water disinfection – SODIS – is a low-cost household intervention used to disinfect water. In this work, we investigate a new solar photoreactor based on V-trough mirrors as alternative to the most used Compound Parabolic Collector (CPC) geometry at pilot scale (54 and 32 L per batch), with the aim of reducing costs and reactor surface’s footprint. An experimental assessment of two key parameters as water recirculation and mirror geometry was carried out. For this study several water-pathogens commonly found in HRW were used, Escherichia coli, Enterococcus faecalis, Salmonella enteritidis and Pseudomonas aeruginosa. Best results were obtained with the V-trough reactor in static condition, where>5-LRV (log-reduction value) for all bacteria tested were reached with a solar-UVA dose of 254 kJ m−2 (90 min). At this operational condition, a total volume of 162 L (3 batches) of water were treated in one full sunny day in Spain (300 min of effective treatment time). A comparison between CPC and V-trough mirrors resulted in similar disinfection efficiencies even if the actinometric results showed that CPC collects 1.58 times more photon flux than the V-trough in the solar-UVA region. These results show the great performance of the V-trough mirror for this application, which is cheaper to produce than CPC and permits treating higher amounts (66% more) of water for the same collector area and same treatment time.