Assessing the environmental impact of wastewater leakage: A case study on grey water and carbon footprints in wastewater collection networks

This study examines the dynamics of mixed industrial and municipal wastewater (MWW) flows in industrial and municipal settings from February 2023 to January 2024. During the study period, total freshwater consumption averaged 85,228 m³/month, with 78 % (66,269 m³/month) converted into MWW. Of this volume, 25 % (16,758 m³/month) was lost due to leakage in the wastewater collection network (WWCN), while the remaining 75 % (49,511 m³/month) reached the discharge stage. The analysis of pollutants indicated that COD was the predominant pollutant across all sampling points, with concentrations of 953.3 mg/L in MWW compared to 1.8 mg/L in freshwater, demonstrating significant contamination. The grey water footprint (GWF) assessment identified COD as the critical pollutant, with peak values reaching 1,260,468 m³/month for generated MWW and 316,449 m³/month for leakage MWW, followed by phosphate (PO₄) contributions. The carbon footprint (CF) assessment estimated that WWCN energy consumption led to emissions of 34,898 kg CO₂/month (0.53 kg-CO₂/m³ MWW). Leakage exacerbated environmental impacts by increasing pollution loads and wasting energy, as untreated MWW bypassed treatment processes. These findings highlight the urgency of mitigating leakage and optimizing MWW management to minimize environmental impacts. Targeted interventions can improve the sustainability of MWW infrastructure and enhance resource efficiency.