## 6 AOPs/adsorption as a Promising Alternative Treatment Technique  
Many studies have shown the negative effects of PPCPs on the environment that we have mentioned before (3), essentially the endocrine-disrupting effects and the risk of the spread of antibiotic resistance [135]. According to the OECD [136], many countries have imposed rules to prevent the risk of developing drugs in the environment. For example, the United States has national regulations on the disposal of hazardous pharmaceutical waste in the health sector, and Germany has developed an environmental checklist for veterinarians and farmers with the aim of reducing the use and release of veterinary pharmaceuticals to the environment. Additionally, Korea uses suspect and non-target screening to identify and prioritize pharmaceuticals for water quality monitoring. In the same order, Australia has a national pharmaceutical collection and disposal program. In this review, we show clearly that one singular method such as conventional treatment, physical treatment methods such as coagulation and adsorption, or advanced oxidation ones, including a combination of oxidizing agents (such as H\({}_{2}\)O\({}_{2}\) and O\({}_{3}\)), irradiation (such as ultraviolet light or ultrasound), and catalysts (such as Fe\({}^{2+}\)), cannot remove them sufficiently. Thus, a combination of two or more processes is required to secure the total elimination of drugs in water. The simultaneous application of ozonation and adsorption for the removal of imidazole, reported by [PERSON] et al. [1], shows that 90-100% of degradation was achieved by ozonation and 10-20% of mineralization. The presence of an adsorbent further reduces toxicity by 30%. Catalytic ozonation associated with adsorption can be effective for the removal of pharmaceuticals. In fact, ozonation degraded the drug products and the adsorbent can remove any remaining pharmaceutical and degradation byproducts. Additionally, [PERSON] et al. [137] show that the application of a combined process of ozone and adsorption (cross-linked chitosan/benonite) for the treatment of solutions containing acetaminophen and amoxicillin was efficiently removed by 84.8% and 82.7%, with an initial concentration of ozone of 0.17 and 0.16 mg/L, respectively (Table 4). Combined photo-Fenton and biological treatment were over 95% efficient, of which 33% corresponds to the solar photochemical process and 62% to the biological treatment [138]. Additionally, Sulfamethoxazole was successfully removed using both catalytic ozonation and adsorption on modified powdered activated carbon (Fe\({}_{2}\)O\({}_{3}\)/CeO\({}_{2}\)-loaded activated carbon) at 2 g/L, applied for only 50 min [139]. [PERSON] et al. [140] studied the removal of 13 pharmaceutical and personal care products (PPCPs) by sequential ultraviolet and ozonation process in a full-scale wastewater treatment plant (Table 4). Authors showed that most of the target PPCPs were effectively removed, and the median removal efficiencies of individual PPCPs, ranging from 13% to 89%, were dependent on their reaction rate constants with molecular ozone. Moreover, [PERSON] et al. [141] studied the removal of eighteen drugs that have a biological removal rate in a full-scale activated sludge plant combined with UV photolysis. They showed that up to 75% of removal was usually found for 17 of the 18 most commonly detected PPCPs, with the only exception being for diclofenac, which has often shown negative values for the rate of biological elimination in activated sludge and has been mainly degraded by UV photolysis. In fact, in treatment water, there are different possibilities of combining advanced oxidation processes such as photo-Fenton/ozonation and photocatalysis/ozonation [142; 143]. At the end of the treatment, the combined processes could generate transformation products more persistent and more toxic than the original pharmaceutical products. The combined processes AOPs/adsorption provided almost complete removal of pollution.