Environmental assessment of desalination processes: Reverse osmosis and Memstill®

Desalination becomes in many parts of the world and also in Europe a promising option to combat water stress in water scarce regions. However, also the question of sustainability and environmental impacts of this technology is in focus of numerous studies and discussions. Especially, the focus is set on high energy demand and disposal of generated brine. In this study, the conventional desalination technology in Europe reverse osmosis (RO) has been compared to the newly developed membrane based technology Memstill® by means of life cycle assessment (LCA). The objective is to define clearly conditions when the environmental impacts are lowest. The results reveal not only the strong dependency of the energy supply and demand but also the potential to reduce the environmental impacts while combining with alternative renewable energy supply. The reverse osmosis can be combined with renewable energies and Memstill® with cogeneration or waste heat. The global warming potential can even be reduced by 98% when RO is combined with wind energy instead of using the electricity grid mix of Spain. Memstill® is especially favourable to RO for feed water with higher salt content due to its almost salt concentration independent energy demand.

► Memstill desalination is more environmentally friendly than RO with conv. energy supply.
► RO with renewable energy sources (wind power, photovoltaic) is the best option
► For highly saline industrial water streams Memstill is more environmental option.
► For brackish water desalination RO is more environmental option.