UV/O₃ and UV/H₂O₂ processes in the decomposition on waste streams generated during membrane filtration of laundry wastewater

One major disadvantage of membrane processes is the generation of a waste stream – reten- tate, which must be treated or disposed in a separate process. The study assesses the effectiveness of the retentate treatment, obtained after the filtration of laundry wastewater, in the UV/O₃ and UV/H₂O₂ processes. The experiments were carried out using two UV radiation sources – a mono- and a polychromatic UV lamp (15 and 150 W, respectively). The UV/O₃ process was carried out for O₃ doses ranging from 2 to 10 mg/dm³, while the H₂O₂ dose during the UV/H₂O₂ process ranged from 3 to 12 mg/dm³. The process's effectiveness was assessed based on changes in the total organic carbon (TOC), cationic and anionic surfactants and triclosan concentrations. Both, UV/O₃ and UV/H₂O₂ processes lead to an over 60% reduction of the TOC concentration. Higher removal degrees of triclosan and surfactants were observed in the processes carried out with the use of a polychromatic UV lamp. The UV/O₃ process allowed for the complete removal of triclosan after 30 min of process duration (at the O₃ = 5 mg/dm³). The toxicological analysis showed a significant decrease in the toxicity of solutions subjected to the implemented process.