Integration of photocatalytic persulfate system with nanofiltration for the treatment of textile dye at pilot scale: Statistical optimization through chemometric and ridge analysis

•PS-TiO2-UVA/NF and PS-TiO2-UVA shows enhanced photo-degradation kinetics.•PS-TiO2-UVA/NF and NF enhance the energy and techno-economic performance.•UV-A and NF reduce electrical energy to 1.45 kWh/m3. The assessment of the sulfate radical-based AOPs (SR-AOPs) in an immobilized reactor combined with various methods for treating brilliant blue FCF (BBF) is presented with emphasis given to energy efficiency, sustainable development, and practicality. The SR-AOPs method, used at the pilot scale under UV light irradiation has a treatment capacity of 0.519 m3/l. It is optimized utilizing the central composite design (CCD) approach for UVA-PS-TiO2 process treatment, an empirical connection concerning removal efficiency was established by choosing as factors TiO2 concentration [0.5–2] g/l, the treatment time [30–180] min, and the concentration of S2O8 [1–3] g/l. The model's significance for the maximal BBF elimination was determined using the variance results (ANOVA) and the adequacy result of Canonical and ridge analysis was also conducted to determine optimal result. In terms of kinetics 3.89 h−1 for NF, 2.61 h−1 for UVA-PS-TiO2/NF, and 0.68 h−1 for UVA-PS-TiO2 and economic evaluation PS-TiO2 with a total cost of 572,32 €/m3 and PS-TiO2NF with an operation cost of 574,28 €/m3. The integration of membrane processes (NF) with UV/ PS/TiO2 allow to reduce the total cost of process and to enhance the kinetic parameters. The technical-economic study demonstrated a successful scenario with a 23-year payback period. [Display omitted]