Pharmaceuticals wastewater treatment via different advanced oxidation processes: Reaction mechanism, operational factors, toxicities, and cost evaluation – A review

•Chemistry, properties, and issues of pharmaceuticals contamination in water are discussed.•Conventional technologies proved ineffective in treating pharmaceuticals wastewater.•Efficiency, mechanisms and pathways of different •OH and SO4•−-based AOPs are discussed.•Effects of different process parameters and cost associated with different AOPs are discussed.•The proposed pathways and ecotoxicities of pharmaceuticals degradation are discussed. Pharmaceuticals comprises different drugs used for treating different infections in human being and animals. The huge quantities of pharmaceuticals used are found to discharge into different water resources and cause different health and environmental problems. The continuous and large-scale discharge of pharmaceuticals increases their persistency which can consequently make them more toxic. The different advanced oxidation processes (AOPs) were found to effectively treat pharmaceuticals contaminated water. The AOPs showed high efficiency in the treatment of acetaminophen, sulfamethoxazole, metronidazole. ciprofloxacin. sulfadiazine, sulfamethazine, amoxicillin, ibuprofen, carbamazepine, and tetracycline. The pharmaceuticals, amitrole, norfloxacin, atenolol, chloramphenicol, berberine, diclofenac, and sulfadiazine showed persistency to some AOPs. The AOPs yield different reactive radicals with predominantly hydroxyl radical (•OH)- and sulfate radical (SO4•−) which showed fast reactivity with pharmaceuticals. Different mechanistic approaches were systematically reviewed which verify the yield, reactivities, and degradation pathways of •OH and SO4•−. Different factors, such as pH, dose of peroxides and activators, level of pharmaceuticals contamination, and common inorganic anions were found to influence the effectiveness of AOPs. The effectiveness of the AOPs in term of cost and detoxification of target pharmaceuticals suggested to select preferably AOPs which are economical and form non-toxic and/or less toxic products. The different challenges, such as treatment of mixture of pharmaceuticals and treatment in real wastewater which can further increase potential of treatment are discussed.