Fouling mitigation in reverse osmosis processes with 3D printed sinusoidal spacers

Jing Wee Koo; Jia Shin Ho; Yong Zen Tan; Wen See Tan; Jia An; Yi Zhang; Chee Kai Chua; Tzyy Haur Chong

doi:10.1016/j.watres.2021.117818

Fouling mitigation in reverse osmosis processes with 3D printed sinusoidal spacers

Water Res. 2021 Dec 1:207:117818. doi: 10.1016/j.watres.2021.117818. Epub 2021 Oct 29.

Authors

Jing Wee Koo¹, Jia Shin Ho², Yong Zen Tan³, Wen See Tan⁴, Jia An⁴, Yi Zhang⁵, Chee Kai Chua⁶, Tzyy Haur Chong⁷

Affiliations

¹ Interdisciplinary Graduate Programme, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore; Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One #06-08, Singapore 637141, Singapore; Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
² Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One #06-08, Singapore 637141, Singapore.
³ School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Avenue, Singapore 637459, Singapore.
⁴ Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
⁵ School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China.
⁶ Engineering Product Development Pillar, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372, Singapore.
⁷ Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One #06-08, Singapore 637141, Singapore; School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore. Electronic address: thchong@ntu.edu.sg.

PMID: 34749103
DOI: 10.1016/j.watres.2021.117818

Abstract

Feed spacers are an essential part of spiral wound modules for reverse osmosis (RO). They create flow channels between membrane sheets and manipulate hydrodynamic conditions to control membrane fouling. In this work, additive manufacturing (Polyjet) was used to print novel sinusoidal spacers with wavy axial filaments connected by perpendicular (ST) or slanted (SL) transverse filaments. When tested with 2 g/L NaCl solution, conventional and SL spacers had similar flux while the ST spacer had about 5-7% lower flux. The pressure losses for ST and SL spacers increased by up to 3 folds depending on the flow condition. In the colloidal silica fouling and biofouling tests, the sinusoidal spacers showed lower membrane permeability decrease of 46% for ST, 41% for SL vs 56% for conventional and 26% for ST, 22% for SL vs 33% for conventional, respectively. Optical coherence tomography images from colloidal silica fouling and confocal images from biofouling tests revealed that fouling patterns were closely associated with the local hydrodynamic conditions. Overall, sinusoidal spacers showed promising results in controlling membrane fouling, but there is potential for further optimizations to reduce channel pressure loss.

Keywords: Additive manufacturing; Biofouling; Inorganic fouling; Sinusoidal spacers.

MeSH terms

Biofouling*
Filtration
Membranes, Artificial
Osmosis
Printing, Three-Dimensional
Water Purification*

Substances

Membranes, Artificial