Improvement of the membrane distillation performance through the integration of different configurations

In this work, the integration of two MD configurations was investigated as a possible mean to reduce the specific energy consumption. In particular, tests of Direct Contact Membrane Distillation (DCMD) and Air Gap Membrane Distillation (AGMD) were carried out on lab-scale modules of 40 cm2. In both cases, a commercial flat polypropylene membrane (Membrana, Germany) of 0.2 ?m was used, and the experiments were carried out by sending distilled water as feed at different temperatures (40°C-50°C-60°C). For the DCMD configuration, different feed flow rates (30 L/h-50 L/h-100 L/h) were also investigated, whereas the operative feed flow rate for the AGMD module was fixed at 100 L/h. Based on the achieved results on single modules, integrated schemes with the feed exiting from the DCMD module sent as coolant stream in the AGMD module -where it is heated by the permeating vapor, before being recycled back to the DCMD module- were analyzed. The integrated DCMD-AGMD systems where finally compared, in terms of specific energy consumption, Gained Output Ratio (GOR) and permeate production, to the single DCMD units.