The problem of drinking water access: A review of disinfection technologies with an emphasis on solar treatment methods

The lack of access to safe drinking water is one of the biggest challenges facing humanity in the 21st century. Despite the collective global effort that has been made, the drinking water sources of at least 2 billion people are faecally contaminated, resulting in more than half a million diarrhoeal deaths each year, with the majority occurring in developing countries. Technologies for the inactivation of pathogenic microorganisms in water are therefore of great significance for human health and well-being. However, conventional technologies to provide drinking water, although effective, present limitations that impede their global application. These treatment methods often have high energy and chemical demands, which limits their application for the prevention of waterborne diseases in the most vulnerable regions. These shortcomings have led to rapid research and development of advanced alternative technologies. One of these alternative methods is solar disinfection, which is recognised by the World Health Organization as one of the most appropriate methods for producing drinkable water in developing countries. This study reviews conventional technologies that are being applied at medium to large scales to purify water and emerging technologies currently in development. In addition, this paper describes the merits, demerits, and limitations of these technologies. Finally, the review focuses on solar disinfection, including a novel technology recently developed in this field.