Application of solar disinfection for treatment of contaminated public water supply in a developing country: field observations Atif Mustafa, Miklas Scholz, Sadia Khan and Abdul Ghaffar ABSTRACT A sustainable and low-cost point-of-use household drinking water solar disinfection (SODIS) technology was successfully applied to treat microbiologically contaminated water. Field experiments were conducted to determine the efficiency of SODIS and evaluate the potential benefits and limitations of SODIS under local climatic conditions in Karachi, Pakistan. In order to enhance the efficiency of SODIS, the application of physical interventions were also investigated. Twenty per cent of the total samples met drinking water guidelines under strong sunlight weather conditions, showing that SODIS is effective for complete disinfection under specific conditions. Physical interventions, including black-backed and reflecting rear surfaces in the batch reactors, enhanced SODIS performance. Microbial regrowth was also investigated and found to be more controlled in reactors with reflective and black-backed surfaces. The transfer of plasticizer di(2- ethylhexyl)phthalate (DEHP) released from the bottle material polyethylene terephthalate (PET) under SODIS conditions was also investigated. The maximum DEHP concentration in SODIS-treated water was 0.38 μg/L less than the value of 0.71 μg/L reported in a previous study and well below the WHO drinking-quality guideline value. Thus SODIS-treated water can successfully be used by the people living in squatter settlements of mega-cities, such as Karachi, with some limitations. Atif Mustafa (corresponding author) Sadia Khan Abdul Ghaffar Department of Environmental Engineering, NED University of Engineering and Technology, Karachi 75270, Sindh, Pakistan E-mail: atifm@neduet.edu.pk Miklas Scholz Civil Engineering Research Centre, School of Computing, Science and Engineering, The University of Salford, Newton Building, Salford M5 4WT, UK Key words | developing country, efficiency, plasticizer, solar disinfection INTRODUCTION One of the key United Nations Millennium Development Goals is to halve the proportion of people without sustain- able access to safe drinking water and basic sanitation by 2015. According to estimates by the World Health Organiz- ation (WHO) (WHO ), more than one-third of the population in developing countries do not have access to safe drinking water. Statistics show that each year 1.8 million people die of diarrhea; 90% of them are children under the age of five, primarily in developing countries. Cur- rently, practitioners and researchers are searching for ways to develop sustainable solutions to reduce the mortality due to water-related diseases. The United Nations Statistics Division reports that approximately 16 million people in Pakistan lack access to improved water. Annual mortality among children below five years of age is 9%. Most of the people in Karachi con- sume microbiologically contaminated water, and this situation leads to high risk for waterborne diseases. The pre- sent scenario demands development of point-of-use (POU) water treatment alternatives that are low-cost, sustainable, low-maintenance and green. There are a number of POU water treatment technologies which encompass heat and UV-based systems, chemical treatment methods and phys- ical removal processes (Peter-Varbanets et al. ). Most people in Karachi and other cities of Pakistan either boil water or use commercially available water purification units. SODIS or solar disinfection is an effective water treat- ment process mostly used to remove pathogens from the 135 © IWA Publishing 2013 Journal of Water and Health | 11.1 | 2013 doi: 10.2166/wh.2012.119 Downloaded from https://iwaponline.com/jwh/article-pdf/11/1/135/395425/135.pdf by guest on 03 May 2019