Chemical-free scale inhibition method for seawater reverse osmosis membrane process: Air micro-nano bubbles

• Published in: Desalination Vol. 461; pp. 1 - 9
• Main Authors: Dayarathne, H.N.P., Jeong, Sanghyun, Jang, Am
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2019
• Subjects: Calcium; Chemical-free; Micro-nano bubbles; Scaling; Seawater reverse osmosis; Scaling; Chemical-free; Micro-nano bubbles; Calcium; Seawater reverse osmosis
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2019.03.008

One of the major problems of seawater reverse osmosis (SWRO) process is the formation of inorganic scales (calcium carbonate, CaCO3) and calcium sulfate, CaSO4)) on the membrane surface, which degrades the filtration performance. Antiscalants have been applied to SWRO plants to overcome the scaling problem. In this study, we used the air micro-nano bubbles (MNBs) as a chemical-free scale inhibition method to improve the overall membrane performance in the comparison with the commercially available antiscalants. During four days of continuous experiments with MNBs, the permeate fluxes declined to 86.5(0.4)% and 83.0(0.5)% with CaCO3 and CaSO4 containing feed solutions, respectively. These values were higher than those obtained with the use of antiscalants in the feed water (CaCO3–63.5(0.4)% and CaSO4–55.8(1.0)%). Membrane fouling characterization results showed that the MNBs efficiently controlled the scaling development on the membrane surface without any chemical addition. [Display omitted] •Air micro-nano bubbles (MNBs) inhibit calcium crystal formation on SWRO membranes.•Continuous MNBs application is effective to improve the SWRO performances.•Scaling inhibition of MNBs is better than antiscalant used in this study.•MNBs helps to achieve a chemical-free SWRO operation.•MNBs can reduce the operational cost and the environmentally negative impacts.