Efficient Roof Selection in Rainwater Harvesting: Hybrid Multi-criteria and Experimental Approach

This study aimed to investigate the effects of different roof configurations on the quality of harvested rainwater (HRW) for sustainable irrigation in agriculture. Three roofing materials (i.e. shingle, galvanized metal, and clay tile) and three roof pitch angles (i.e. 5 degrees, 30 degrees, and 42 degrees) were used at pilot-scale. HRW was characterized in order to determine the roof type and roof slope effect on the HRW quality. HRW from galvanized metal roofs was of higher quality in terms of turbidity and pathogen microorganisms. HRW from shingle and clay tile roofs was treated with a sequential ultrafiltration (UF) membrane and ultraviolet (UV) disinfection system to meet the European Union (EU) water reuse standards for irrigation. The decision-making mechanism was used to select the most appropriate roof configuration. The results showed the significance of financial (21.89%) and environmental (19.75%) aspects. Also, the Escherichia coli (E.coli) content (7%) is the most determinant factor in HRW, followed by the operational cost (6.78%), and reduced runoff (5.73%). Among the roof configurations, galvanized metal roofs, specifically the metal roof with 5 degrees, outperformed others due to their structural, technical, and environmental advances.