Comparative life cycle assessment of end-of-life options for reverse osmosis membranes

With continuing growth in the reverse osmosis water treatment industry and the finite lifespan of the membranes, the number of membrane modules requiring disposal is expected to drastically increase over time. This study aimed to provide a quantitative assessment of the environmental impact from membrane manufacturing and its impact on the desalination process, using the tool of life cycle assessment. The results showed no significant difference between the manufacturing of 16″ and 8″ elements, and that module fabrication contributed to less than 1% of the CO2-e emissions for the production of potable water from seawater. The study also looked at the environmental impact of a number of proposed end-of-life disposal options for membranes within the context of the Australian desalination industry. The results of the study show that membrane reuse over one year is more environmentally favourable to 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. 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. © 2014 Elsevier B.V. All rights reserved.

The results of this study show that direct reuse is the most environmentally favourable option for end-of-life membranes, and that landfill is the least favourable option. In terms of aversion of waste from landfill, incineration results in the least mass requiring disposal, while the reuse scenarios feature the greatest impact. Although the most environmentally favourable option, due to its virgin membrane production offset, it is clearly highlighted that the reuse option does not target the actual disposal of the membrane module, and is highly dependent of reuse lifespan. The results also show that recycling and disposal in EAF are both relatively favourable options, with EAF being particularly suitable for the minimisation of waste volume. While the study focuses on the Australian geographical setting, the principal findings can be easily applied to the international context. In addition to the relevance for RO reuse and recycling, this LCA study is a valid comparison of traditional disposal scenarios for all plastic solid waste. Thus, it can be used in future studies and policy making on general waste management decisions. Overall, this study provides valuable insight into the end-of-life RO membrane options that are currently being considered for further development. It shows the potential environmental benefits that could be realised through an organised reuse system and encourages the development of a membrane disassembly and component recycling system for final disposal. This study will provide valuable information for membrane users in selecting end-of-life options, as it contained well defined criteria for the environmental viability of each option.