A novel concentrated solar membrane-distillation for water purification in a building integrated design

Abstract

Solar-assisted Vacuum Membrane-Distillation provides a lower-energy alternative to water treatment, particularly desalination in dry areas. While horizontally integrated (roof-top) decentralized treatment systems exist, vertically integrated (balcony) water treatment systems remain unexplored. This study improves upon a previous solar-VMD system with a compound parabolic collector and integrate it onto the vertical faces of a building. The novel VMD system generates a flux of >8 L water per square meter of membrane area per hour when operating at a temperature above 65 °C and with a 15 kPa vacuum pressure during peak solar conditions (>800 W/m2). This system's performance was identical under clean-water and desalination operating modes, reinforcing the use-case of urban desalination. Furthermore, a numerical model was developed and validated to be utilized for parametric study. Finally, an economic analysis has shown that the system has a levelized cost of water of 21.5 USD/m3, with the cogeneration of heat via hot water (i.e., a levelized cost of heat of 0.015 USD/kWh) off-setting costs. Assuming a use-case of rural implementation whereby water transport costs dominate, the payback period of the design is around 2 years. Ultimately, this demonstrates a viable decentralized water treatment/hot-water system that can alleviate water scarcity in arid areas.