Life-cycle assessment of two potable water reuse technologies: MF/RO/UV–AOP treatment and hybrid osmotic membrane bioreactors

• Life cycle assessment (LCA) of a hybrid UF-osmotic MBR (UFO-MBR) was conducted.
• Results were compared to LCA of MF–RO–UV–AOP treatment train for potable reuse.
• Energy demand and greenhouse gas emissions for UFO-MBR are slightly higher.
• MBR and RO operations have the highest impacts on the LCA of UFO-MBR.
• FO materials have the highest impact on UFO-MBR LCA.

A life cycle assessment tool and methodology were used to study two potable reuse treatment schemes: a full-advanced treatment (FAT) approach and a hybrid ultrafiltration osmotic membrane bioreactor (UFO-MBR). FAT combines conventional wastewater treatment followed by low-pressure membrane filtration, reverse osmosis (RO), and ultraviolet advanced oxidation processes (UV–AOP). The UFO-MBR couples biological treatment processes with forward osmosis (FO) membranes and ultrafiltration (UF) membranes in one integrated system. RO is coupled with FO in the UFO-MBR process to produce ultra-pure water and a reconcentrated draw solution (DS) for reuse in the FO process. Construction material, energy demand, and chemical use data were collected and calculated to determine the energy use and a subset of environmental impacts of each system. Results from the LCA illustrate that the energy use and environmental impacts of FAT are lower than those of UFO-MBR treatment. The higher impacts of UFO-MBR treatment were associated with the required large area of the FO membrane and high RO energy use. UFO-MBR treatment was further assessed using higher permeability FO membranes and RO energy recovery. Following simulation of process optimization, the environmental impacts of UFO-MBR were brought much closer to those of FAT.

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