Influence of dye class on the comparison of direct contact and vacuum membrane distillation applied to remediation of dyeing wastewater

Abstract

This work investigated the influence of dye class on permeate flux and color rejection by comparing direct contact membrane distillation (DCMD) and vacuum membrane distillation (VMD) applied to remediation of dyeing wastewater. The same operating system at the feed side was used and the driving force of each configuration was determined. Reactive and disperse dye solutions were considered, and a commercial membrane was employed. Final color rejection > 90.79% was obtained, and water was recovered at the permeate side (final normalized permeate flux up to 38.92 kg m⁻²day⁻¹kPa⁻¹). VMD showed higher normalized permeate flux when compared to DCMD. However, the performance according to dye class depended on MD configuration. Reactive dye resulted in higher permeate flux than the disperse dye solution in DCMD. Contrarily, disperse dye solution showed higher permeate flux in VMD. The formation of a concentration boundary layer at the permeate membrane interface was suggested with disperse dye solution in DCMD, decreasing thus the driving force. In VMD, the boundary effect is negligible with disperse dye solution. This result implies that the VMD performance in the textile industry may depend more on driving force rather than the dye class of the dyeing bath.

Keywords:

• Dye deposition
• poly(tetrafluoroethylene)
• textile effluent
• water reuse
• wastewater reclamation

Acknowledgments

The authors are grateful for the support given by the Central Laboratory of Electron Microscopy (LCME-UFSC).

Conflict of interest

The authors declare that they have no conflict of interest.

Additional information

Funding

This work was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001.