A water footprint inventory for a textile organization: a case study in the denim washing industry based on the integrated reverse osmosis system.

The consideration of scarcity and overexploitation of freshwater at the organizational level has increased interest in the water footprint (WF). The water footprint measures freshwater use for activities, taking into account water consumption and pollution contamination by classifying consumed water into groundwater and surface water (blue water), rainwater (green water), and polluted water (grey water). This study aims to identify a comprehensive WF inventory analysis for a denim washing company and assess the grey WF based on the effluent concentration of pollution indicators (chemical oxygen demand [COD], suspended solids [SS], ammonium nitrogen [NH4-N], and phenol) measured monthly in 2021. The company used well water for its operations, which constituted 61.79% of the total water use of the facility; water used by the company by reverse osmosis (RO) accounted for 37.60% of total water consumption, and rainwater made up 0.61% of the volume of water used overall. The grey water footprints of COD, SS, NH4-N, and phenol were calculated as 59,981.53 m3, 31,747.21 m3, 10,514 m3, and 48,190 m3, respectively. The results illustrate that the COD, which accounted for 40% of the pollutants, had the highest grey WF in the company, corresponding to the amount of freshwater required to assimilate pollutants to meet water quality standards. In addition, the effect of the RO system on the blue WF of this company was analyzed by considering two different scenarios. Reverse osmosis considerably affected the blue WF, accounting for over 37% of this company's water use. It suggests that a wastewater treatment plant using RO is an ideal option for recovering water. The main contributions of this study are comprehensively assessing the water footprint components of the denim washing company and understanding sector-specific water footprint at the organization level.