Discussion on the application of UV/H₂O₂, O₃ and O₃/UV processes as technologies for sewage reuse considering the removal of pharmaceuticals and personal care products

The applicability of O₃, UV/H₂O₂ and O₃/UV treatment processes as technologies for water reuse considering pharmaceuticals and personal care products (PPCPs) removal was investigated. Electrical energies required for the effective removal of various PPCPs in secondary effluent were 0.09 kWh/m³, 0.54 kWh/m³ and 1.09 kWh/m³ for O₃, UV/H₂O₂ and O₃/UV treatments, respectively, showing that O₃ treatment is the most cost-effective treatment option for the PPCPs removal. O₃ treatment showed the effective PPCPs removal at O₃ dose of 6 mg/L; however, the formation of bromate is expected for O₃ treatment using O₃ dose of more than 4 mg/L. In particular, bromate formation will be a critical issue when the reclaimed water is used for direct/indirect potable reuses. Therefore, in order to suppress the bromate formation as well as achieve the effective PPCPs removal, O₃/UV treatment will be recommended. UV/H₂O₂ treatment will be also a profitable treatment method because no bromate will be formed during the process. The evaluation for ecological risk of PPCPs by the applied processes showed that all the processes could decrease the ecological risk caused by parent PPCPs considerably. This means that the investigated treatment processes can play an important role in reducing unpredictable side effects caused by PPCPs in the aquatic environment.