Rejuvenation of Mildly Degraded Reverse Osmosis Membranes

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2021-9
Kayhan, Bende Merve
Depletion of freshwater resources is one of the inconvenient truths of the 21st century. Appropriately treated municipal wastewater can be utilized for industrial, agricultural, and potable purposes which is a sustainable option rather than discharging it into the environment. Today, one of the main technologies used in desalination of sea water and wastewater reuse is reverse osmosis (RO). The RO technology uses membranes to achieve the separation of water from contaminants, and it is very efficient in rejecting monovalent ions, bacteria and viruses. Especially, the use of thin-film composite polyamide (TFC PA) membranes has brought significant advantages in the water treatment industry since they offer high permeate flux and high salt rejection performance. However, the polyamide-based active layer of these membranes is prone to failure by chlorine attack used in disinfection and membrane cleaning operations. These operations are necessary for municipal wastewater treatment for reuse, but they cause decrease of the useful life of membranes. Thus, rejuvenation of membranes, which ensures salt rejection restoration, arises as a promising method to repair damaged membranes. This thesis investigates the performance of a commercial rejuvenation agent, which acts as a coating layer on the membrane surface. In this experimental study, the membranes were first degraded under various chlorine concentrations, contact time and pH values and their performance was determined. Thereupon, damaged membranes were treated with the rejuvenation agent, and their performance after rejuvenation was recorded in terms of permeate flux and salt rejection. The change in the chemical structure of membranes was examined via FTIR-ATR method. The results showed that membranes were mildly degraded, and rejuvenation agent successfully restored the salt rejection of mildly degraded membranes.

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Citation Formats
B. M. Kayhan, “Rejuvenation of Mildly Degraded Reverse Osmosis Membranes,” M.S. - Master of Science, Middle East Technical University, 2021.