3D printed spacers for organic fouling mitigation in membrane distillation

• Published in: Journal of membrane science Vol. 581; pp. 331 - 343
• Main Authors: Castillo, Erik Hugo Cabrera, Thomas, Navya, Al-Ketan, Oraib, Rowshan, Reza, Abu Al-Rub, Rashid K., Nghiem, Long D., Vigneswaran, Saravanamuthu, Arafat, Hassan A., Naidu, Gayathri
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2019
• Subjects: 3D printed spacers; Membrane distillation; Organic fouling; Triply periodic minimal surfaces; Wastewater; Triply periodic minimal surfaces; 3D printed spacers; Wastewater; Membrane distillation; Organic fouling
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2019.03.040

3D printing offers the flexibility to achieve favorable spacer geometrical modification. The role of 3D printed spacers for organic fouling mitigation in direct contact membrane distillation (DCMD) is evaluated. Compared to a commercial spacer, the design of 3D printed triply periodic minimal surfaces spacers (Gyroid and tCLP) - varying filament thickness and smaller hydraulic diameter enhanced DCMD fluxes by 50–65%. The highest DCMD flux was obtained with the 3D tCLP spacer due to its specific geometrical design feature. However, its design characteristics resulted in higher channel pressure drop compared to 3D Gyroid spacer. Moreover, 3D Gyroid spacer exhibited superior fouling mitigation (lower membrane organic mass deposition and reversible membrane hydrophobicity with humic acid solution), attributed to its tortuous design that repelled foulants. 3D Gyroid spacer was effective in achieving high water recovery (85%) while maintaining good quality distillate (10–15 μS/cm, 99% ion rejection) in DCMD with wastewater concentrate that contained high organics, mixed with inorganics. In MD, high organic contents minimally affected MD fluxes but reduced membrane hydrophobicity. Repeated DCMD cycles showed that organic pre-treatment as well as cleaning-in-place of membrane and spacer are essential for achieving high recovery rate while maintaining a stable long-term DCMD operation with wastewater concentrate. [Display omitted] •3D spacers increased MD fluxes by 50–65% compared to a commercial spacer.•Organics cause marginal flux decline but impact membrane hydrophobicity in MD.•3D Gyroid spacer with tortuous zigzag design was suitable for repelling foulants.•MD with 3D Gyroid spacer achieved 85% water recovery from low organic wastewater.•Cleaning-in-place and organic pre-treatment are vital for MD wastewater treatment.