Accelerating the process of solar disinfection (<scp>SODIS</scp>) by using polymer bags

Abstract

Abstract BACKGROUND Solar water disinfection ( SODIS ) is a point‐of‐use water treatment that consists of exposing microbiologically‐contaminated water in plastic bottles to sunlight. Replacing bottles with bags can accelerate the SODIS process, reduce the costs of transport and distribution, improve usability and facilitate its promotion, especially in emergencies. This work evaluated the solar disinfection capacity and resistance to deterioration of different polymer bags. RESULTS Preliminary disinfection tests with commercial E. coli were performed using bags made of food‐grade polyethylene ( PE ) along or joined with layers of bio‐oriented polypropylene ( PPO ), polyamide ( PA ) and polyethylene terephthalate ( PET ). The PE bag was the fastest device achieving 6 log‐reduction within 60 min of normalized time. All the tested bags presented better performance than the PET bottles used in the conventional SODIS method. Position of the bags and bottles (vertical/horizontal) had no relevant influence on the disinfection efficacy. Two improved bags (tap, better seal, volume: 4 L), made of PE and PE joined with ethylene vinyl acetate ( EVA ) were tested with simulated field‐conditions water. Both bags reached the detection limit of wastewater derived Enterococcus spp. , the PET bottle did not. Ageing tests over 5 months revealed breakages in 100% of the PE bags, while the PE / EVA bags remained intact and disinfected water faster than new PET bottles. CONCLUSION This work concludes that the PE / EVA bags are good substitutes for the PET bottles as SODIS containers. © 2016 Society of Chemical Industry