Chapter 11. Advanced UV LEDs-based Photolytic Treatment for Removal of Microbial and Organic CEC in Water

Abstract

UV LEDs are emerging as promising light sources for removal of contaminants of emerging concern (CEC) in water. UV LEDs operate at relatively lower electrical power as compared to mercury and xenon lamps. Even though the optical radiant power output is considerably lower compared to visible-light LEDs; they are considered as environmentally sustainable alternatives due to the toxicity and ban on mercury. UV light can disinfect water as UV irradiation causes inactivation of microbes by altering the structure of its cellular components. Oxidants, upon UV-light irradiation, generate radicals that can degrade organic chemicals. These chemicals are used in PPCP, fertilisers and pesticides, and as industrial compounds. These compounds, along with microbes, are considered as CEC. CEC are commonly found in water sources in low concentration (ng L−1–µg L−1). They have adverse effects on the aquatic life and human health and need to be removed from water sources. The efficiency of photolytic processes depends on the geometry of the photolytic chamber and the uniformity of the light irradiation. These parameters, estimated by computational and experimental methods for batch and flow-through models of operations reported for LED-based photolytic reactors, are discussed here. The performance of LED photolytic sources for the removal of organic and microbial CEC in terms of EEO are discussed. Water-treatment prototypes based on an LED photolytic process for small-scale POU application, to large-scale pilot studies are presented.