Intensification of water reclamation from textile dyeing wastewater using thermal membrane technologies – Performance comparison of vacuum membrane distillation and thermopervaporation

Abstract

Vacuum membrane distillation (VMD) and themopervaporation (TPV) were compared as intensification processes for water reclamation from textile dyeing wastewater. The results showed the potential of each technique: VMD increased the permeate flux while TPV resulted in complete dye rejection for both tested dye classes. In VMD, the dye rejection of disperse dyeing wastewater resulted in 97.5%. In this case, TPV using a dense membrane should be considered for high-quality water reclamation. However, the VMD using a porous membrane may show higher pure water reclamation with wastewater resulted from reactive dyeing. Both processes recovered water from dye solution, but the separation mechanisms are totally different: based on a difference in volatility in VMD by using a porous membrane and based on a difference in membrane affinity in TPV by using a dense membrane. The obtained results suggest that VMD and TPV may be integrated into the same operating system next to the dyeing machine. This flexibility in the textile industry may overcome difficult points in the individual processes according to the dye class by simply changing the membrane. The application of both processes is interesting since a heat recovery from dyeing wastewater is possible, and no additives are required.