Chapter 10 - UV-based advanced oxidation process for the treatment of pharmaceuticals and personal care products

Abstract

The removal of pharmaceuticals and personal care products (PPCPs) from drinking water and wastewater is of great concern for environmental scientists and engineers. UV-based advanced oxidation processes (AOPs), such as UV/H2O2, UV/chlorine, and UV/persulfate processes, via the production of hydroxyl radicals (HO•), reactive chlorine species (RCS), and sulfate radicals (SO4•-), have attracted great interest in water treatment. This chapter describes the fundamentals and efficacy of UV-based AOPs to transform PPCPs, including antibiotics, nonsteroidal antiinflammatory drugs, β-lactams, β-blockers, antiepileptic drugs, and anticonvulsants. First, the radical chemistry for different AOPs, including the production and consumption of radicals, is discussed, along with the effects of water matrices. Then, the kinetics and energy requirements of the PPCPs by different AOPs are described. Third, the toxicity alternation is discussed. The basic reactions of PPCPs with different radicals, i.e., HO•, RCS (Cl•, Cl2•-, and ClO•), and SO4•-, in the AOPs highlight that RCS and SO4•- are more selective than HO• for the abatement of PPCPs. Additionally, the multiple radicals as a result of the UV/chlorine and UV/persulfate processes are all beneficial. However, the efficiencies are highly affected by water matrices, such as the dissolved organic matter (DOM), alkalinity, and halides, through radical scavenging and/or the formation of secondary radicals. The UV/chlorine and UV/persulfate AOPs are less affected by water matrices and show better efficacy and lower energy requirements in real water treatment than the UV/H2O2 AOP. The alternation of toxicity during UV-AOPs resulted from the radical (HO•, RCS, or SO4•−)-induced transformation of PPCPs. In most cases, PPCPs are not completely mineralized but are partially oxidized into transformation products by the three UV-AOPs, and the formation and degradation of the toxic products are affected by various conditions, which lead to an increase or decrease in the overall toxicity of treated water. Moreover, there are many types of toxicity (such as acute, chronic, and genotoxicity) with no uniform standard for a global assessment. Therefore, a toxicity evaluation is necessary to estimate the potential risks of treated water by UV-based AOPs.