Field Tests of the Solar Water Detoxification SOLWATER Reactor in Los Pereyra, Tucumán, Argentina

The SOLWATER reactor prototype is composed of two tubes containing a supported heterogeneous photocatalyst (Ahlstrom© paper impregnated with titanium dioxide), and two tubes containing a supported photosensitizer (designed and provided by G. Orellana, Universidad Complutense, Madrid, Spain). The tubes are placed on a CPC collector and run in series. Electricity is provided by a solar panel, and the recirculation rate is $ca$$13Lmin−1$⁠. Total volume in the feed tank plus tubes is $20L$⁠. The reactor was designed and constructed by the consortium of a European research project whose objective is on the development of a fully autonomous solar reactor system to purify drinking water in remote locations of developing countries. The prototype was placed in the yard of a shanty house in Los Pereyra, Tucumán, Argentina. Water to feed the reactor is taken from the shallow aquifer through an open well. This water is contaminated with high counts of coliforms and Enterococcus faecalis. It also contains widely variable levels of Pseudomonas aeruginosa. The chemical composition of the water shows high levels of natural organic matter and of various inorganic pollutants. The reactor has been running since February 22, 2005. This paper presents the results collected in three months of operation. Around $4hr$ operation on a sunny day, and $5-6hr$ on a cloudy day are required to totally destroy fecal coliforms and Ent. faecalis. Even $24h$ after the experiment is concluded, no cultivable bacteria are seen by the membrane filtration method (measured colony forming units after $24hr=0$⁠). On the other hand, a small number of total coliforms remain (a few percent or less of the original count) at the end of some of the latest experiments. Possible explanations for this result are the drop in ambient temperature, the decrease in solar irradiance, and the exhaustion of the catalyst and sensitizer. P. aeruginosa is much more resistant, and only partial destruction is observed in those time intervals. The evolution of chemical parameters is also presented and discussed.