Direct contact membrane distillation applied to saline wastewater: parameter optimization

Freshwater availability is suffering from an increasing pressure created by the growing demand, depleting resources and the environmental pollution. Desalination of saline wastewater is a possibility to supply households, industry and agriculture with water. However, technologies applied such as reverse osmosis, evaporation or electro dialysis are energy intensive. Membrane Distillation (MD) is a competitive technology for water desalination. In our study, Response Surface Methodology is applied to optimize the Direct Contact Membrane Distillation (DCMD) treatment of synthetic saline wastewater. The aim was to enhance the process performance and the permeate flux Jp (L/m 2 ·h) by optimizing the operating parameters: temperature difference Δ T , feed velocity Vf , salt concentration [ NaCl ], and glucose concentration [ Gluc ]. DCMD process has led to a remarkable high permeate quality with 99.9% electrical conductivity reduction and more than 99.9% COD removal rate. The predicted optimum permeate flux Jp is 34.1 L/m 2 ·h that was reached at Δ T = 55.2 °C and with a feed velocity Vf = 0.086 m/s as the two most influencing parameters. The created model has shown a high degree of correlation between the experimental and the predicted responses with high statistical significance.