Submitted to: Symposium for Ammonia and Odor Control from Animal Production Facilities
Publication Type: Proceedings
Publication Acceptance Date: 1/15/2001
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Heat drying of wastewater solids from municipal wastewater treatment plants is becoming prevalent as biosolids management regulations become more restrictive. The product from heat drying is sometimes odorous as dry pellets or as 'wetted' pellets. The odors, although unregulated, can be important for marketability and public acceptance of the product. The reasons for the odors are usually a result of upstream processing and management of wastewater solids prior to drying. Heat dried pellets were evaluated from several plants with various upstream processing, that included wastewater solids that were: 1) all undigested, 2) primary undigested, 3) primary digested, 4) waste activated sludge (WAS) undigested, 5) all digested, and 6) WAS lime stabilized. The primary objective of this investigation was to determine the types of odors that exist in heat dried pellets from various processes. Carbon disulfide, dimethyl disulfide and carbonyl sulfide were the most common reduced sulfur odors detected from all heat dried pellets, regardless of the processes. Odor panel indicated all the pellets produced offensive odor. Trimethyl amine was detected only from the WAS lime stabilized sample and may have been the cause of the high odors from these pellets (DT of 5100). When innoculated with soil, the stabilized products (both digested and lime stabilized) possessed the least odors. It is because a product that is already stabilized will not be susceptible to biological activity and related odors as unstabilized pellets. Therefore, in a land application event, where inoculation of microbes is likely, it is anticipated that the odors from unstabilized products may be substantial.