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Assessment of End-Of-Life Opportunities for Reverse Osmosis

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Assessment of End-Of-Life Opportunities for Reverse Osmosis Assessment of End-of-Life Opportunities for Reverse Osmosis Membranes Will Lawler A thesis in fulfilment of the requirements for the degree of Doctor of Philosophy School of Chemical Engineering Faculty of Engineering March 2015 i. Abstract Reverse osmosis (RO) membranes are now core to modern desalination processes and are widely used around the world. Based on the increasing number of desalination plants, and the finite lifespan of the membranes, the resulting number of used RO modules to be discarded is becoming a critical challenge. The overall aim of this study is to identify, develop and assess alternative end-of-life options for used RO elements and investigate the associated technical readiness, environmental impact, financial considerations and legislative challenges. The assessed end-of-life alternatives include, direct reuse of the old membranes within lower throughput systems; chemical conversion into porous, ultrafiltration (UF) like filters; direct reuse or recycling of the various module components; various energy recovery techniques, and landfill disposal. The results show that direct reuse is a promising application that can be utilised with minimal additional treatment or infrastructure; however, module storage techniques are a critical consideration, particularly as membrane drying has a significant and irreversible impact on membrane performance due to pore collapse in the polysulfone support layer. The method for chemical conversion with controlled exposure to NaOCl has been optimised, resulting in promising organic and virus removal properties, comparable to commercially available 10 – 30 kDa molecular weight cut off UF membranes; however, there was significant variation in hydraulic performance, ranging from 8 – 400 L.m-2.h-1.bar-1. A detailed life cycle assessment was completed and demonstrated that module fabrication contributed less than 1% of the CO2-e emissions for the production of potable water from seawater desalination, and that direct reuse over one year is more environmentally favourable than landfill disposal, regardless of the transportation distance required. However, in terms of direct reduction of waste to landfill, incineration provided the greatest benefit, at the expense of increased greenhouse gas emissions. Applying the knowledge generated within this study, an interactive online educational tool has been developed using a dynamic multi criteria decision analysis system, providing information 1 on end-of-life options to membrane users. Overall, this study provides detailed quantitative information for membrane users and manufacturers to enhance their decision making process when it comes to end-of-life membrane options. 2 ii. List of Publications Journal Papers Lawler, W., Bradford-Hartke, Z., Cran, M.J., Duke, M., Leslie, G., Ladewig, B.P., Le- Clech, P., 2012. Towards New Opportunities for Reuse, Recycling and Disposal of Used Reverse Osmosis Membranes. Desalination 299, 103–112. Lawler, W., Antony, A., Cran, M., Duke, M., Leslie, G., Le-Clech, P., 2013. Production and Characterisation of UF Membranes by Chemical Conversion of Used RO Membranes. Journal of Membrane Science 447, 203–211. Lawler, W., Alvarez-Gaitan, J., Leslie, G., Le-Clech, P., 2014. Comparative Life Cycle Assessment of End-of-life Options for Reverse Osmosis Membranes. Desalination 357, 45–54. Lawler, W., Leslie, G., Le-Clech, P. Assessment of Membrane Drying and Subsequent Rewetting Techniques. To be submitted to the Journal of Membrane Science. Peer Reviewed Conference Papers Lawler, W., Wijaya, T., Antony, A., Leslie, G., Le-Clech, P., 2011. Reuse of Reverse Osmosis Desalination Membranes. Paper and oral presentation. IDA World Congress. Perth. Lawler, W., Leslie, G., Le-Clech, P., 2015. Decision Making Tool for End-of-Life Reverse Osmosis Membrane Users. IDA World Congress. San Diego. Under Review. Conference Proceedings Lawler, W., 2011. Reuse, Recycling and Disposal of Used Reverse Osmosis Membranes and it’s application to steelmaking. Oral presentation at Sustainability Symposium - Future Pathways for Reducing Greenhouse Gas Impacts of Materials. Sydney, Australia. 3 Lawler, W., Reusing Old Reverse Osmosis Membranes in Humanitarian Projects. Oral presentation at Early Career Symposium Adelaide, November 2011. Lawler, W., Antony, A., Leslie, G., Duke, M., Le-Clech, P. Fate of Aged Reverse Osmosis Membranes. Poster presentation at IWA Leading Edge Technologies conference. Amsterdam 2011. Lawler, W., Rodricks, J., Le-Clech, P. Converted RO membranes for decentralised gravity driven water treatment. Poster presentation at IWA Toronto 2013. Lawler, W., Le-Clech, P. The end of it: Alternative options for reuse, recycling and disposal of old RO membranes. Oral conference presentation at IMSTEC 2013. Lawler, P. Le-Clech, P. Developing new applications for old reverse osmosis membranes. Oral conference presentation at IMSTEC 2013. 4 iii. Acknowledgements First and foremost I would like to thank my supervisor, Dr. Pierre Le-Clech, without whom this thesis would not have been possible. Thank you for taking me on board and teaching me about the world of membranes, research and academic life. I thoroughly enjoyed the journey, and I hope that you did too. Secondly, I would like to thank my partner, Dr. Gemma Reynolds, for her infinite support and patience. The journey through post graduate life was significantly more bearable with you to share the experience with. I would also like to thank everyone at UNESCO Centre for Membrane Science and Technology at UNSW. This includes my co-supervisor Dr. Greg Leslie, whose expertise in the membrane industry was invaluable to my work. Also a big thanks to Dr. Alice Anthony, for all of your input into my work and your help. It was a pleasure to get to know you, your husband Subbu, and your wonderful kids over the last few years. Thank you to Dr. Yun Ye for all the support in the lab over the years, and also Dr. Deyan Guang in the early days of my work. Thank you to my fellow students and friends in the membrane centre, it was quite a ride and I wish you all the best in your futures. Also thanks to my honours students, Joel, Philip and Sarah, who taught me a lot about what it is to be a supervisor and teacher. Thank you to Juan and Zenah for your help with my life cycle assessment work. Special thank you to Dr. Shane Cox, my honours thesis supervisor, friend, advisor, mentor, and employer. You started me off in the world of water treatment, and I continue to learn from you every day. Thank you to my closest friends Joe, David and Kosta, with whom I shared the PhD adventure. Also big thanks to Alex, for providing the soundtrack for my research and all the good times. 5 I would also like to give a big thank you to my parents and siblings. You may not have understood what I was doing for the last few years, but you put up with me and supported me anyway. I would also like to acknowledge the financial support of the National Centre of Excellence in Desalination Australia, which is funded by the Australian Government through the Water for the Future initiative. Collaborative partners from Monash University, Sydney water, Water Corporation, Dow and the SkyJuice Foundation are also gratefully acknowledged. Special thank you to Victoria University and particularly Dr. Marlene Cran for your close participation on this project. Finally, thank you to Dr. Ludovic Dumee, who brought me into the world of SAXS and helped me greatly with the analysis and modelling. I learnt a lot from you and our journey to the synchrotron. 6 iv. Table of Contents i. Abstract ................................................................................................................. 1 ii. List of Publications ................................................................................................. 3 iii. Acknowledgements ................................................................................................ 5 iv. Table of Contents .................................................................................................. 7 v. List of Figures ...................................................................................................... 11 vi. List of Tables ....................................................................................................... 15 vii. Nomenclature ...................................................................................................... 17 Introduction .......................................................................................................... 19 Justification ................................................................................................... 19 Aims and objectives ...................................................................................... 21 Chapter Descriptions .................................................................................... 23 Literature Review ................................................................................................. 25 Introduction ................................................................................................... 26 Reverse Osmosis Membranes: Process and Materials ................................. 27 Membrane Desalination Processes ....................................................... 27 Membrane Structure .............................................................................. 29 Membrane Operating Conditions and Lifespan ...................................... 31 Waste Management .....................................................................................
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