How LEDs Will Change Water Purification

LEDs have been a defining factor in many technological innovations, and water treatment is no exception. Although mercury lamp accidents are rare when lamps are installed correctly, the benefits of UV-C LEDs have begun to outweigh the need to stay with the status quo.

Ultraviolet (UV) light has been naturally purifying water for centuries. With clear skies, our sun can inactivate water-based pathogens in six hours minimum. Cloudy skies or unclear water causes imperfect conditions. These conditions allow for bacteria to grow and make natural water sources unsafe to use. Fortunately, we have developed several types of water disinfection, ranging from chemicals to UV lamps. Although these are all beneficial to human health, some are more environmentally beneficial than others.

The Need for Change

Advancements in chemistry and technology have resulted in multiple effective methods to purify water. Chemicals, such as chlorine, were the first widely used disinfection method and in many cases remain the primary means of purification. Chemical treatments dissolve pathogen cells entirely and, until ultraviolet (UV) treatment, were the best available option. However, there are downsides to using chemicals in drinking water. They can be toxic to aquatic life, create harmful byproducts, and are not effective against all pathogens (such as Cryptosporidium) . The chemicals used for disinfection are also highly corrosive and can cause safety and environmental risks during transportation and storage. (NSFC, National Small Flows Clearinghouse)

Although UV disinfection is considered safer than chemical use, all conventional UV lamps typically contain 20-200 milligrams of mercury and are susceptible to breakage during transportation, handling, and operation. Conventional UV lamps hold their mercury either in a liquid form (more common in medium pressure lamps) or in an amalgam (more common in low pressure, high output lamps). Accidents and improper procedures increase the risk of exposure.

The United Nations Environmental Programme (UNEP) initiated the Minamata Convention on Mercury to protect human health and the environment from anthropogenic emissions and releases of mercury. The UNEP has set the goal for mercury to be phased out of production by the year 2020. In 2013, organizations and governments were asked to discourage the use of mercury starting immediately, and 127 countries signed to ratify the removal of all mercury by the year 2020. While it is unclear whether UV lamps for water disinfection will receive an exemption from this regulation, it is clear that alternatives should be actively considered.