In treating textile wastewater, the application of membrane bioreactor (MBR) technology showed high efficiency in COD and BOD5 removal. However, insufficient colour removal was achieved for possible reuse. The aim of the work presented in this paper was to test the performance of chemical advanced oxidation on the elimination of the colour downstream of an MBR. To improve the quality of the membrane bioreactor effluent three different oxidation treatments were tested at lab-scale: ozonation, chlorination and hydrogen peroxide oxidation. Colour, COD and BOD5 were controlled in order to assess the effectiveness of each process. For chlorination, even with 250 mg/L (active chlorine) only 80% colour removal (SAC_in = 14; SAC_out = 2.8) was achieved which is considered unsatisfactory. For hydrogen peroxide, the colour removal was even poorer; it was just 10% at a concentration of 250 mg/L. In contrast, good results were obtained by ozonation. By using only 38 mg/L within 20 minutes, it was possible to achieve the reuse recommendation with a satisfactory colour removal of 93% (SAC_in = 14; SAC_out = 0.98). The results showed that ozonation was the most promising method.

In this study, Pb doped ZnO nanoparticles were synthesized by a sol-gel technique for the sorption of Reactive Black 5 (RB5) textile dye in aqueous solution. The ZnO:Pb (2 and 4%) nanoparticles have been characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and cryogenic nitrogen adsorption method (BET). The average size of the synthesized nanoparticles is less than 100 nm and the surface areas were 18.8 and 20.8 m²/g, respectively for ZnO:Pb 2% and ZnO:Pb 4%. Batch sorption experiments were performed for color removal of RB5 dye at ambient temperature and 30 mg/L dye concentration. The central composite design (CCD) with response surface methodology (RSM) was used to study the effect of sorption condition (pH, nanoparticles dose and contact time). The significance of independent variables and their interactions were tested by analysis of variance (ANOVA). The optimum conditions of color removal were reached at pH = 7, 2 g/L dose of nanoparticles and a contact time of 79 min. The color removal performances was 79.4% and 98.1% for ZnO:Pb 2 and 4% respectively. The pseudo-second-order model described well the removal rates while the Langmuir model fitted well the adsorption isotherms.

Ultrafiltration is essential for wastewater treatment, but it faces challenges such as selectivity, control, and fouling reduction. Incorporating nanoparticles into membranes enhances retention, boosts permeability, and limits fouling, improving overall performance. This study explores the properties of PVDF/Ag-ZnO composite membranes, highlighting the influence of silver-doped zinc oxide nanoparticles on membrane structure, performance, and antimicrobial effect. The non-solvent-induced phase separation (NIPS) method successfully led to the preparation of composite membranes; this method used different doses of silver-doped zinc oxide (Ag-ZnO) nanoparticles with Poly(vinylidene fluoride) (PVDF). Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and water contact angle measurements were used to validate the influence of nanoparticles on the composite membrane (PVDF/Ag-ZnO) structure. Conversely, morphology (porosity, surface rigorosity), hydrophilicity, and permeability were analyzed through contact angle, image analysis, and flux measurement. In addition, the membranes were tested for antimicrobial activity against E. coli. Membrane performance shows that the incorporation of 20% w/w Ag-ZnO resulted in improved water permeability, which was about 2.73 times higher than that of a pure PVDF membrane (192.2 L·m⁻²·h⁻¹·bar⁻¹). The membrane porosity showed a linear increase with the number of NPs. The resultant asymmetric membrane was altered to increase the number of pores on the top surface by 61% and the cross-sectional pore surface by 663%. Furthermore, a high antibacterial activity of Ag-ZnO 20% was shown.