Treatment of dye solutions by vacuum membrane distillation

In this work, the vacuum membrane distillation (VMD) process has been applied to treat water containing different types of dyes. The influence of operating parameters, as feed temperature, feed flow rate, feed concentration, on the permeate flux and on rejection has been investigated. In all experimental tests, a complete rejection has been achieved and pure water has been recovered at the permeate side. Furthermore, experiments with water as feed have been carried out before and after the tests with dyes, in order to analyze the effect of fouling on the performance of the VMD. The water vapor fluxes immediately after the tests with dyes were higher than the values registered before the tests, probably due to an interaction with the polymeric membrane material which promotes a swelling of the membrane when in contact with the dye solutions. However, initial fluxes are recovered after prolonged cleaning with only water.