Influence of feed/permeate velocity on scaling development in a direct contact membrane distillation

• Feed and permeate velocities influenced DCMD performance and scaling development.
• Suitable velocity combination enhanced recovery ratio with reduced pumping energy.
• Surface crystallisation was reduced with suitable velocity combination.

In this study the performance and scaling pattern of a direct contact membrane distillation (DCMD) was investigated at different feed and permeate flow velocities (vf and vp). The results indicated that both vf and vp influenced DCMD performance and scaling development. A combination setting of vf = 0.8 m s−1 and vp = 1.1 m s−1 resulted in a similar permeate flux as vf and vp = 1.1 m s−1 with a 30% higher recovery ratio and 60% lower pumping energy membrane analysis demonstrated bulk crystallisation tendency at high flow velocity ranges (1.1–2.2 m s−1), while membrane surface crystallisation was dominant at lower flow velocities (0.5–0.8 m s−1). A combination setting (vf = 0.8 m s−1 and vp = 1.1 m s−1) showed beneficial outcome of reduced surface crystallisation tendency.

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