Room 208, Chemical Sciences Bldg
- University of New South Wales, BE. Chemical Engineering (2006 – 2009)
- 2009-2011: Graduate Engineer, Sydney Water, New South Wales, Australia
Project Title: Reuse, recycling and Disposal Options for Used Reverse Osmosis Membranes
Reverse osmosis (RO) membranes are now widely used as core treatment process in modern desalination plants, which have been build or are being build all around the country. Sea water desalination plants can use tens of thousands of 14Kg membranes modules that are primarily made up of plastics and due to deterioration in performance, these membranes need to be replaced every 4-6 years. At present there are no options other than disposing of the membranes in landfill available to membrane users, and this disposal method affects the environmental sustainability of the RO desalination process.
This study aims to evaluate and develop the technological readiness and financial assessment for the various strategies proposed to membrane users. In order to efficiently assess the relative benefits of the proposed options, life cycle assessment will be carried out. Following the well-accepted waste disposal hierarchy, reuse options (where the membrane is directly utilised in another applications) are generally preferred over recycling (where physical and/or chemical transformation of the original material is first needed). While reuse and recycling have the potential to offer a second life to aged RO modules, new options for the sustainable disposal of RO membranes are also required. Here are described the various options which will be considered within the scope of this study:
- Reuse of RO membrane modules. There is a strong potential to directly reuse the spent RO membranes with little treatment (i.e. cleaning) or ideally with no treatment at all. After evaluation and validation of the old RO performances, the membranes could be easily reused in a lower throughput application. Factors to be considered will include technical feasibility via pilot testing of disposed membranes from desalination plants, marketability, and assessment of financial costs for transport and storage.
- Recycling of RO. Different chemical treatments (i.e. with chlorine- and permanganate-based compounds) will be tested to remove the polyamide active layer present on the membrane surface. Once stripped from the dense layer, treated modules have the potential to be reused as porous membranes; if the integrity of the supporting layers and the overall stability of the module elements are not significantly challenged. The polymer material removed from the RO modules (dissolved in a solution from the conversion process) could be captured and treated to recover valuable polymer material. After physical transformation, old RO membranes could also be used as structural element (traffic bollard, water guttering, water storage container).
- Sustainable disposal. New methods for disposal of RO at the end of their lifetime will be considered, including energy recovery options, where the combustion of the polymeric materials could produce energy. The use of old RO modules in electric arc furnace steel-making to substitute coke and in low-temperature gasification to produce syngas will be studied. Finally, separation and shredding components for use as filler material, aggregate, and reuse of membrane parts (i.e. endcaps, housing, seals and possibly permeate tube) will be investigated.
NCEDA Project Presentation: