Concentration of glycerol from dilute glycerol wastewater using sweeping gas membrane distillation

• A SGMD system was used for glycerol recovery from wastewaters.
• The effects of various operating parameters were studied.
• The contribution and the interactions of parameters were analyzed by Taguchi method.
• Feed temperature was found as the most influential parameter on permeation flux.

In this work, experimental results for the concentration of dilute glycerol wastewater using membrane distillation (MD) with a microporous hydrophobic flat-sheet PTFE membrane are reported. Experiments were performed using the sweeping gas mode of the MD (SGMD) process. The effects of various operating variables, such as feed temperature, glycerol concentration in aqueous phase, feed flow rate and sweeping gas flow rate were studied. A Taguchi analysis has been performed on the experimental results which determined the effects and contribution of each of the factors on the distillate flux and the interactions between the operating variables. Results showed that the most influential factor was feed temperature. The second significant contribution was observed for the sweeping gas flow rate. Feed concentration had a negative effect on the distillate flux. At optimum conditions (i.e. 65 °C, 400 mL/min, 1 mass%, and 0.453 Nm3/h), the Taguchi model predicted the value of the response (the distillate flux) as 20.93 L/m2 h, which had good agreement with the experimental results.