Authors: Mr Will Lawler, Mr Thomas Wijaya, Dr Alice Antony, Prof. Greg Leslie, Dr Pierre Le-Clech
Presenter: Mr Will Lawler, PhD Student – The University of New South Wales
Presentation: Environment and Public Health Part I, Wednesday, September 7, 5.30-6.00 pm, Bellevue 2
Currently, membranes used in reverse osmosis (RO) desalination are generally disposed of via landfill. For economic and environmental reasons, other reuse, recycle and disposal options must be considered and investigated. This study aimed to assess the technical feasibility of removing the dense polyamide (PA) active layer of RO membranes, with the intent to reuse degraded RO into porous low pressure membranes. The study assessed the ability of three degrading solutions (NaOH, KMnO4 and NaOCl) to remove the active layer, and used clean water filtration and salt rejection to compare the effect of different exposure intensities. The most promising results were found using NaOCl, membranes treated with at least 300,000 ppm.h of NaOCl presented an increased permeability to 175 ± 4 L.m-2.h-1.bar-1 with less than 4% salt rejection. This shows that NaOCl performed significantly better than KMnO4 as a degrading solution, with NaOH showing the least promising results. The fouling behaviour of the degraded RO membranes was also compared to commercially available ultrafiltration (UF) membranes, to which they displayed similar fouling characteristics and by using LC-OCD the molecular weight cut off (MWCO) of the reused membranes was estimated to be 5-10 kDa.
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