Odor emission is one of the most important constraints in waste management. Although land application of wastewater sludge (biosolids) is sensible means of treatment and recycling, odor complaints from the public have led to the failure of otherwise successful biosolids application projects. The major objective of our project is to improve the understanding of the mechanisms through which odor is generated and disseminated in wastewater sludge. The findings will be used to control odorous compounds from land-applied biosolids into the air. Our methods are based on laboratory studies of the biological, chemical and physical properties of anaerobically digested biosolids, such as controlled anaerobic digestion experiments, simulation of the chemical treatments of biosolids used in treatment plants, and the measurement of textural properties and odorant flux rates. A recent technique called Solid Phase Micro Extraction (SPME) is used to collect and concentrate the odorants for GC/MS analysis. This project may allow us to apply our results at different specific application sites with more intelligent processing and land-based recycling of biosolids.