UV LED TECHNOLOGY FOR WATER DISINFECTION: A SPECTRUM OF POSSIBILITIES

Abstract

Access to clean and safe drinking water is a basic human right, as declared by United Nations General Assembly in 2010 (Resolution 64/292). Maintaining and achieving safe water quality is a crucial factor in promoting public health and economic development. Despite technological progress in certain areas, in the 21st century, approximately 29% of the world’s population (2.1 billion people) lack access to drinking water at home. There exist multiple challenges of water scarcity, pollution, and inadequate infrastructure that require a concerted effort from governments and communities to aid the progress of providing safe drinking water worldwide. Climate change is expected to exacerbate water scarcity in many parts of the world, with some regions facing a 50% reduction in available water by 2050. By investing in water infrastructure, promoting water conservation and implementing effective water treatment methods, we can ensure that everyone has access to this essential resource. Traditionally, various methods have been employed for treating water, such as chlorination, sedimentation, filtration, and coagulation. Since the early 1950s, Ultraviolet (UV) light sources have been used by local and national bodies for water disinfection in the final stages to eliminate pathogenic microorganisms. The use of UV light has been found to reduce the growth of microorganisms by inhibiting their reproduction when the DNA/RNA within the microorganism absorbs radiation. Sunlight is the most commonly available natural source of UV. However, it doesn't provide enough UV radiation for quick and effective disinfection. For this reason, artificial UV sources like mercury lamps, light emitting diodes (LEDs), or plasma lamps have been explored for generating UV wavelengths of interest. It is worth noting that sunlight has been used in disinfection processes in low– and medium– income countries using a process called solar water disinfection (SODIS). The technology of UV LEDs is relatively new, with the first commercial UV LED being available in 2003, and has evolved significantly since its discovery with applications in multiple fields like catalysis, air, and surface disinfection etc. Nevertheless, there are still significant challenges associated with the technology and disinfection process that need to be investigated and resolved. Treatment of drinking water and wastewater using UV sources can be energy–intensive and requires optimization to minimize energy consumption. While it may seem that more input radiation to the water matrix can result in faster and higher disinfection rates, it is essential to balance treatment effectiveness, cost, and energy efficiency...