Process engineering optimization of nanofiltration unit for the treatment of textile plant effluent in view of solution diffusion model

• Published in: Egyptian journal of petroleum 2016-03, Vol.25 (1), p.79-90
• Main Authors: Shaaban, Ahmed Mohamed Farid, Hafez, Azza Ibrahim, Abdel-Fatah, Mona Amin, Abdel-Monem, Nabil Mahmoud, Mahmoud, Mohamed Hanafy
• Format: Article
• Language: English
• Subjects: Color and COD removal; Dye-house wastewater; Nanofiltration; Solution diffusion model; Spiral-wound membrane
• ISSN: 1110-0621
• DOI: 10.1016/j.ejpe.2015.03.018

[Display omitted] •Effects of operating conditions on dye/salt rejections by NF-technique were studied.•Color removal and COD reduction were achieved.•Solution diffusion model describes permeate flux and kinetic parameters.•Solute mass transfer coefficient is correlated vs. cross velocity as power function.•Studying pressure effect on mass transfer coefficient, water and salt permeability.•Studying salt concentration effect on mass transfer, permeability and polarization. A nanofiltration (NF) based separation process is used to treat the effluent from a textile plant to allow for water reuse and fulfill environmental standards. The wastewater effluent contains reactive black (RB5)- and disperse (DR60) dyes. A NF-unit model E2 series with HL 2521 TF spiral wound module was used to carry out experiments. 90 & 93% color removal and COD reduction for RB5 and 98 & 95% for DR60 were achieved. A parametric study of the separation process is undertaken to characterize the effects of the operating variables, e.g., trans-membrane pressure, dye/salt concentration in the feed, temperature, and cross flow velocity. The solution diffusion model was used to develop power correlations to calculate the permeate side solute mass transfer coefficient as a function of effective cross-flow Reynolds number. In contrast to the commonly assumed constant hydraulic solvent permeability, a non-linear relationship was developed over the applied trans-membrane net driving pressure. The latter correlates exponentially with salt permeability for both dyes. The effects of feed salt-content on solute mass transfer coefficient, water and salt permeability, concentration polarization, dye hydrophobicity and ionic strength were studied. Results were used to assess engineering specifications of a commercial size NF-plant (500m3/d capacity).