Rainwater harvesting solar pasteurization treatment systems for the provision of an alternative water source in peri-urban informal settlements

Abstract

The aim of the study was to monitor the operational sustainability and efficacy of rainwater harvesting solar pasteurization (SOPAS) treatment systems installed in a local informal settlement in Stellenbosch, South Africa. Indicator organisms, cations and anions were routinely monitored in the tank water before (untreated) and after SOPAS treatment, while molecular-based techniques were used to identify and quantify pathogens associated with rainwater sources. The operational sustainability of the systems was monitored to determine the volume of water produced, the total water usage by the end-user households and the required system maintenance. Anions and cations analyzed for in the untreated and SOPAS treated rainwater were within national and international drinking water guidelines, with the exception of zinc which exceeded the limits in all samples. Additionally, the total coliform, E. coli, fecal coliform and heterotrophic bacteria counts exceeded drinking water guideline limits in 100%, 55%, 36% and 100% of the unpasteurized tank water samples (n = 11), respectively. However, a minimum pasteurization temperature of 66 °C was required to reduce all indicator organism counts to within drinking water standards. Quantitative PCR analysis confirmed that Legionella spp., Pseudomonas spp. and Salmonella spp. were still detected following SOPAS treatment. Monitoring of the operational sustainability of the systems indicated that minimal system maintenance was required and that the systems were effectively able to provide water to the participating households during the rainfall periods. Based on microbiological indicator analyses, the SOPAS systems may be used in rural areas and informal settlements for the provision of an alternative water source.