Chapter 17 - Degradation of organic micro-pollutants by ultraviolet radiation

Abstract

Micro-pollutants trigger water quality and cause undesired health and environmental effects (such as feminizing side effects in males, change in hormonal balance, behavioral changes, resistance development in microbes, and toxicity). These pollutants originate from various sources and enter waterbodies through different pathways. The existing wastewater treatment plant (WWTP) operation is unable to remove several emerging micro-pollutants, thus it acts as a source of dissemination. Advanced oxidation processes (AOPs) are widely used for the degradation of recalcitrant (toxic and nonbiodegradable) organic contaminants from wastewater and convert them into nontoxic by-products using free radicals. This chapter introduces the various micro-pollutants found in water and wastewater, and also highlights the drawbacks of conventional treatment technologies included in WWTP operations. The authors explain the use of ultraviolet (UV) alone and in combination with other treatment methods for enhanced degradation of various organic micro-pollutants. This chapter explicitly provides details on UV-based AOPs such as (1) UV with ozone (O3), (2) UV combined with hydrogen peroxide (H2O2), and (3) UV and titanium oxide (TiO2) combinations along with other methods for micro-pollutant removal. The mechanisms of UV-based AOPs in the degradation of organic micro-pollutants, the principals involved in various reactions, operating parameters, and recent applications along with case studies are elaborated in the chapter. In addition to limitations of the UV treatment processes, future perspectives are also discussed, with a goal of achieving a clean environment and pristine water for the generations to come.