Odour monitoring as an unconventional tool for sewage sludge management in wastewater treatment plants

The management of sewage sludge generated by wastewater treatment plants (WWTPs) must comply with stringent regulations to prevent adverse impacts. Selecting appropriate sludge treatment is highly dependent on accurate sludge characterization, which traditionally involves comprehensive laboratory analyses of physical, chemical, and biological parameters. These analyses are time-consuming, costly, and do not allow for real-time decision-making. Furthermore, sewage sludge represents one of the main odour emission sources, posing potential nuisances. This research explores the use of odour emission monitoring as a rapid, non-conventional approach for supporting sewage sludge management decisions. To validate the methodology, experimental analyses were conducted on a full-scale WWTP. Sludge samples were characterized through conventional parameters, including chemical oxygen demand (COD) and biochemical oxygen demand (BOD₅). Simultaneously, odorous emissions were quantified in terms of odour concentration, according to EN 13725:2022. The comparison between chemical and sensorial analyses demonstrate statistically significant correlations between odour concentration and key COD and BOD5 of sewage sludge. The findings suggest that odour monitoring can serve as a practical, rapid, and cost-effective proxy indicator for sludge stability assessment, offering a complementary tool to conventional laboratory analyses. This approach can facilitate timely management decisions, optimize sludge treatment processes, and mitigate odour related impacts.