Rejuvenation of discarded RO membrane for new applications

Production and characterisation of UF membranes by chemical conversion of used RO membranes

“…As a result, an exposure of 300,000 ppm h of NaOCl was recommended as the standard protocol for the continuing investigation of RO membrane conversion. A similar methodology has been used in a recent study to convert seawater RO (SWRO) membranes with NaOCl into brackish water RO (BWRO) and to briefly consider the formation of UF membranes through prolonged exposure [33]. Exposure intensities from 7,000 to 300,000 ppm h were tested, and the results were consistent with the effects of prolonged exposure discussed in Lawler et al [24].…”

“…Comparably, a previous study obtained a converted flux of 124 L m -2 h -1 bar -1 when applying a similar conversion protocol (300,000 ppm h of NaOCl exposure) to an in house manufactured PA/PSf TFC SWRO membrane, following a wetting phase [33].…”

“…Based on work shown here and previously published [24,33], it has been concluded that this controlled removal of the active layer is possible but challenging. This is due to the varied response of different membrane types to the conversion process and the rapid removal of the active layer as exposure time increases.…”

Transformation of end-of-life RO membranes into NF and UF membranes: Evaluation of membrane performance

“…Despite, the salt rejection capability decreased 95% (from 92.57 to 4.4%), the permeability range obtained did not clearly show ultrafiltration properties as reported other authors [17,18]. Consequently, further morphological study was performed.…”

“…However, the concentration range of chlorine used was low and it might have not been high enough for a significant transformation. Ambrosi and Tessaro [16] tried to recycle also end-oflife membranes by K 7 MnO 4 but the resulting permeability of the transformed membranes were lower than those obtained employing high dose and exposure time of NaOCl [17,18]. Lawler et al demonstrated that the transformation of end-of-life RO membranes to UF membranes was possible due to the complete removal of the active PA layer.…”