Identification and Odor Generation Pattern of Odor-Causing Compounds in Digested Biosolids During Long-Term Storage

The main objective of this research was to identify the compounds responsible for persistent odors in biosolids during long-term storage using olfactometry measurements and to determine their generation pattern with regard to time of appearance and decline using gas chromatography-mass spectrometry (GC-MS). Headspace analysis was used to quantify shortterm odor-causing organic sulfur compounds and persistent odors from compounds such as indole, skatole, butyric acid and p-cresol for an incubation period up to 150 days. A unique odor generation pattern was observed for each of the compounds analyzed for all the dewatered cakes tested in this study. Dewatered cake samples were also analyzed to determine their detection threshold by a trained odor panel and the results were consistent with the general pattern of odor generation observed in this study. Although the highest odors during biosolids incubation came from sulfur compounds, the persistent odors must be managed as part of a comprehensive sludge management approach.