Solar Photocatalytic Water Disinfection of Escherichia coli, Enterococcus spp. and Clostridium Perfringens using different low-cost devices

Abstract

BACKGROUND: The purpose of this work was to evaluate the disinfection capacity of two handmade low-cost devices based on solar photocatalytic disinfection (SPC-DIS): a plastic bottle (2 L) with a cylinder inside coated with TiO2 doped with zinc and a glass reactor (9 L) with an inner cylinder coated with pure TiO2. Disinfection experiments of wastewater-derived Escherichia coli, Enterococcus spp. and Clostridium perfringens (104–105 CFU per 100 mL) were carried out under natural sunlight during winter. RESULTS: Clostridium perfringens was the most resistant microorganism and E. coli the least in all cases. The SPC-DIS bottle achieved 100% disinfection for E. coli, but only 98.97% for Enterococcus spp. and 96.28% for C. perfringens. The SPC-DIS reactor achieved, under optimum operating conditions, 100% disinfection for E. coli, 100% for Enterococcus spp. and 99.44% for C. perfringens. Maximum sustainable flow rate (22 L min−1) and maximum illumination ratio (1:2) were the best operating conditions. Operating with recirculation (interrupted illumination) favored C. perfringens spore formation. Best kinetic models were biphasic for E. coli and log-linear for Enterococcus spp. and C. perfringens. CONCLUSION: The two new devices showed higher disinfection capacity than common PET bottles (increase in disinfection rates up to 1.5 and 4.6 times), proving to be promising alternatives to the traditional method SODIS. © 2015 Society of Chemical Industry