Evaluation of the impact of water reclamation on blue and grey water footprint in a municipal wastewater treatment plant

Sustainable water management is one of the research areas that is gaining importance worldwide today. In this work, water footprint assessment was conducted in a wastewater treatment plant before (called as WWTP-C for the year of 2018) and after (called as WWTP-WR for the year of 2021) adding the water reclamation unit, using the method proposed by Water Footprint Network (WFN). Additionally, the impact of water reclamation on blue water footprint (WFblue) and grey water footprint (WFgrey) was investigated from an environmental sustainability point of view. Water footprint of WWTP-C and WWTP-WR was evaluated as 2.2 m3 and 2.3 m3; respectively. While energy consumption and sludge treatment were determined as the major components for WFblue, total nitrogen (TN) and total phosphorus (TP) were the most limiting pollutants for WFgrey. Environmental benefit of water reclamation to reducing the WFgrey was determined as 44 % for the year of 2021. The sensitivity analysis results showed that high variability in the values of maximum allowable concentration of pollutants by national regulations has significantly affect the sustainability of WFgrey.

Automated summary

In this study, the water footprint of a wastewater treatment plant (WWTP) was assessed before and after the addition of a water reclamation unit. The impacts of water reclamation on blue and grey water footprints were investigated. The results showed that the water footprint increased slightly after the addition of the water reclamation unit. Energy consumption and sludge treatment were identified as major contributors to the blue water footprint, while total nitrogen and total phosphorus were the most limiting pollutants for the grey water footprint. The environmental benefit of water reclamation in reducing the grey water footprint was determined to be 44%.