ODOROUS EMISSIONS FROM BIOSOLIDS AND SEPTAGE STORAGE AND DEWATERING FACILITIES

The Indian River County Department of Utility Services had been receiving odor complaints from neighbors of the Central Wastewater Treatment Facility (Central WWTF). The Central WWTF includes a Regional Sludge Facility (RSF), which had been the focus of these complaints. In response to the complaints, the Department of Utility Services commissioned odor control improvements to the RSF. The improvements focused on improving collection of odorous emissions within the belt filter press area of the RSF. Hoods and covers were constructed over the existing belt filter presses and conveyors so that emissions from these sources could be more efficiently collected and treated.Understanding that these improvements did not comprehensively address odor emissions from the Central WWTF, the Department of Utility Services invited PBS&J to visit the plant and offer guidance on approaches to further reduce odorous emissions. In April 2002, PBS&J visited the Central WWTF to observe operations and conduct a preliminary assessment of odorous emissions from all the treatment processes at the Central WWTF. Following the visit, PBS&J suggested that significant odorous emissions might be originating from several facilities other than the RSF. The existing Solids and Septage Storage Tanks, Aerobic Digesters, Filtrate Equalization Basin, and Anoxic Tank were specifically identified as facilities that might be emitting significant odorous emissions. PBS&J recommended a mass odor emission inventory be conducted for these facilities. The inventory would quantify the mass of odor emissions generated at various locations and identify the odorous compounds that would require control and/or treatment. By defining mass odor emission rates at each facility, the County would be better able to objectively prioritize the most important odor generation areas and better assess the types of improvements and corresponding odorous compound removals that were needed.Based on the mass odor emission inventory and the results of air dispersion modeling, new odor control systems were recommended for the Anoxic Tanks and modifications were recommended for the RSF scrubber.