6.2.6 Advanced oxidation processes
Advanced oxidation processes (AOP) facilitate the conversion of
contaminants into into less toxic and more easily degradable substances
by generating free radicals, specifically hydroxyl radicals (Ikehata et
al., 2008).UV radiation is typically the first step in the production of
hydroxyl radicals, which can be produced using a variety of techniques,
including ozone (O3), hydrogen peroxide (H2O2), photolysis with
ultraviolet light, homogeneous Fenton reagent, heterogeneous
semiconductors, electrolysis with ultrasound (sonolysis), and microwave
radiation (Gogoi et al., 2018; Pavithara and Jaikumar, 2019). Sichel et
al. (2011), , using UV/chlorine advanced oxidation, degraded ECs such as
17α- ethinylestradiol, sulfamethoxazole, diclofenac, benzotriazole,
carbamazepine, tolyltriazole, iopamidol, desethylatrazine and
carbamazepine. AOPs based on ozone treatment have been shown to be
effective in treating wastewater containing a variety of
pharmaceuticals, including angiotensin II receptor antagonists, cocaine,
its metabolite benzoylecgonine, anti- inflammatory medicines,
cholesterol-lowering statins, and antibiotics (Ibannz et al. 2013).
Research has demonstrated the efficacy of AOPs in degrading
pharmaceutical compounds in water, either individually or in combination
with other degradation methods—over 80% and up to 90%—when used
with various processes namely coagulation, flocculation, nanofiltration,
and electrocatalytic oxidation (Pavithra & Jaikumar, 2019;
Rayaroth et al., 2016).