An approach to develop grey water footprint accounting

Grey water footprint (GWF) is an indicator that represents the water quality issues embedded in producing a product in form of freshwater volume. This indicator converts the pollution loads to the equivalent volume of freshwater with respect to the assimilative capacity of the receiving water body. This study develops the method of accounting multiple-pollutant GWF with ecological perspective. For demonstrating the developed methodology, original samples were taken from trout farms in the Kabkian River, south-western Iran, and the pollution exports are calculated in first step. In the second step, river is modelled for determining the local-oriented water quality standards. Finally, total multiple-pollutant GWF is determined. Here, equations are developed for considering dissolved oxygen (DO) in accounting GWF due to the critical role of this parameter in aquaculture and fish production. In addition, a state-of-the-art coefficient is introduced to alter the formulation for including the environmental issues of receiving water body in accounting GWF. This can provide a framework for considering Eutrophication, saline intrusions, minimum environmental flow and DO deficit of river, in addition to the risks of micropollutants in water footprint assessments. Nevertheless, the results of case study show that GWF is nitrogen-related for trout farming. It equals 195 m(3)/ton but it may fluctuate depending on the local development strategies and their consequences on the environmental issues. Consequently, the proposed methodology can broaden the prospect of the application of GWF and enhance the role of environmental capacity in this indicator.