A visualization system was designed for a real-time observation of scales during direct contact membrane distillation (DCMD). The system was composed of a MD module, a camera and light sources. Firstly, visibility of the scales with the system and correlation between detected spots and wetting were assessed during the MD process using a polyvinylidene fluoride (PVDF) 0.45 μm membrane. The white spots were observed in the captured images from the visualization system and got broader with the electrical conductivity (EC) increase in permeate. It was verified that the spots indicated the pores blocked by the CaSO4 scales. The wetting occurred through the white spots if the pressure was applied. Therefore, the high wetting potential area could be identified with the suggested visualization system during the MD operation in real-time. The visualization system was applied to the MD process under different permeate temperatures (20 and 55 °C). The visualization system successfully detected the pore blocking related with different scale formation according to the temperatures at the membrane surface.
Bibliographical noteFunding Information:
This research was supported by grants (Code 17IFIP-B065893-05 and 18IFIP-B146829-01 ) from Industrial Facilities & Infrastructure Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government (South Korea). This research received financial support from the Korea Institute of Science and Technology ( 2E28120 ). The authors also acknowledge support from the KU-KIST Graduate School Project .
- Membrane distillation
- Real-time observation
- Visualization system