Simulation of dual systems of greywater reuse in high-rise buildings for energy recovery and potential use in irrigation

As the demand for new and green energy sources continues to increase, freshwater resources are under increasing pressure, prompting the use of nonconventional production alternatives. Greywater can be used for human, agricultural and green purposes; however, it can also be used for environmentally friendly energy generation. Greywater disposed from high-rise buildings (over 100 m in height) is an additional alternative that can be utilized for energy generation and subsequently also for agricultural and/or ornamental irrigation. This manuscript demonstrates options among the many available possibilities for producing energy from free-falling greywater in high-rise buildings (HRBs'). The idea is to install turbines on different levels of the building to generate energy and use it immediately in the building itself. Although the amount of energy produced is limited according to preliminary assessments, extra work is required to improve the recovery systems. The results demonstrated many existing alternatives for turbines locations, referencing to a countless number of storage places and turbine types. The special purpose WaterGEMS simulation software was chosen for the analysis.