Carbon footprint analysis and carbon neutrality potential of desalination by reverse osmosis for different applications basd on life cycle assessment method.

Reverse osmosis (RO) technology, as a mainstream method of water treatment, is widely used worldwide for water resource acquisition. However, in the context of the current global effort to achieve carbon neutrality, its carbon footprint has gradually attracted attention. The aim of this study is to systematically assess the carbon footprint of the RO water treatment process during its full life cycle and to explore the carbon reduction potential of the RO water treatment process under different decarbonization scenarios. To analyze RO's carbon footprint in different applications, this study constructed a life cycle model of the RO water treatment process under the business model, calculating footprints for seawater reverse osmosis (SWRO), brackish water reverse osmosis (BWRO), and reclaimed water reuse. Results showed carbon footprints of 3.258, 2.868, and 3.083 kg CO₂-eq/m³ for the three applications, with operational power as the main carbon source, followed by chemical use, membrane production, and disposal. The carbon footprint of the three applications can be reduced by up to 93.23%, 87.81%, and 51.12% by predicting the grid structure, waste recycling and disposal methods, and energy consumption after process operation optimization. Sensitivity analyses of key process variables showed that the carbon footprint was more sensitive to influent temperature, system energy recovery, and influent salinity than membrane product life. Thus, the study recommends a comprehensive strategy involving renewable energy, energy efficiency improvements, and operational optimization to lower RO's carbon footprint and support carbon neutrality.