Reconciling water circularity through reverse osmosis for wastewater treatment for a hyper-arid climate: a life cycle assessment

Aiming to reconcile the water cycle and combating water scarcity, this study investigates the tradeoffs of upgrading tertiary wastewater treatment with ultrafiltration (UF) membrane, and reverse osmosis (RO) using life cycle assessment (LCA). The tradeoffs investigate if the higher burden of UF/RO is justified by providing higher quality of water returned to the cycle for arid regions that rely on seawater desalination. The tertiary treatment wastewater inventories are built based on activated sludge by vertical loop reactor (VLR), rim clarifiers and ultraviolet (UV) disinfection. The inventories for the UF/RO trains are build according to the largest wastewater treatment facility worldwide. Open-loop, and consequential modeling principles were applied using the credited municipal water, while considering the local electricity-water cogeneration system for a hyper-arid region. The analyses are conducted on two levels: UF/RO versus advanced tertiary wastewater treatment with UV disinfection, and UF/RO versus the conventional seawater desalination. Wastewater treatment has reduced consumption of scares brackish water abstraction by 71.3%, a credible improvement towards reconciling the water cycle, that could be achieved by 40% of the current environmental burden and cost using tertiary treatment. If the UF/RO was legalized to be utilized for amenities use to substitute for desalinated water beside aggregation, only then the environmental and economic marginal increase could be justified.