Capability of 19-L polycarbonate plastic water cooler containers for efficient solar water disinfection (SODIS): Field case studies in India, Bahrain and Spain

The small treated volume (typically ~2 L) associated with polyethylene terephthalate (PET) bottles that are most frequently used in solar water disinfection (SODIS), is a major obstacle to uptake of this water treatment technology in resource-poor environments. In order to address this problem we have conducted a series of experiments in Spain, Bahrain and India, to assess the efficacy of large volume (19 L) transparent plastic (polycarbonate) water cooler/dispenser containers (WDCs) as SODIS reactors to inactivate Escherichia coli and Enterococcus faecalis, under strong natural sunlight. Reduction values of 6 log10 units (LRV = 6.0) have been observed using WDCs in each location. Additional comparisons between 2-L PET bottles and 19-L indicate that WDCs provide bacterial inactivation similar in both systems. SODIS disinfection experiments in turbid water (100 NTU) in both reactors showed very good inactivation efficiency. LRVs of 6 were obtained for E. coli in both WDC and 2-L PET bottles, and in the case of E. faecalis LRV = 5 and 6 were observed in Spain and Bahrain, respectively. These studies demonstrate that under conditions of strong sunlight and mild temperature, 19 L water dispenser containers can be used to provide adequate volumes of SODIS treated water for households or larger community applications such as schools or clinics in the developing world