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ODOR CONTROL STUDY 2 . 4 Conclusions From Mass Emissions Inventory Based on the air emission sample program and mass emissions inventory, the following conclusions can be made : • Odor emissions are highly related to H2S and organic sulfur emissions at the Central WWTF . Therefore , reductions in sulfur emissions should reduce off-site odor impacts . • The three major odor and sulfur emission sources at the Central WWTF are , in order: ➢ The RSF Scrubber ➢ The Anoxic Tank ➢ The Sludge and Septage Storage Tank Fugitive Emissions • H2S is the primary odorant for most of the sources . However, there is significant H2S and organic sulfur in the exhaust from the RSF Scrubber. The scrubber is only removing 40 to 50 % of the sulfur delivered to the scrubber. Improvements in chemistry and controls will be needed to reduce sulfur content in the scrubber exhaust and improve the effectiveness of the scrubber. • Good sulfur mass balances were performed for the RSF , which provides good confidence in the mass emission rates and the accuracy of the mass -emissions inventory. The mass balance also indicates that fugitive emissions from the existing Dewatering Building do not likely contribute to off:site odor impacts . • Confidence is not as high for estimates of fugitive emissions from the Sludge and Septage Storage Tanks . Emissions from this source are difficult to estimate and are likely to be very dynamic . Emissions from this source may be substantially lower or higher than estimated . Current estimates are that 25 % of the sludge emissions were escaping the existing odor collection systems . Many dampers on the odor collection system were closed during the sampling program . Opening these dampers and closing the openings in the top of the tank will likely improve the capture of fugitive emissions from these sources . • The recent elimination of the Filtrate Equalization Basin , Aerobic Digesters , and completion of the belt filter press hoods and covers have resulted in a 25 to 33 % reduction of sulfur emissions from the Central WWTF . Most of the emission reductions are attributable to the elimination of the Aerobic Digesters and Filtrate Equalization Basin . The new belt filter press hoods will probably reduce fugitive emissions in the Dewatering Building . However, open grating over the filtrate sump will likely allow significant emissions to escape into the Dewatering Building . 1- QT 14 Indian River County, Central Wastewater Treatment Facility PBS&J #071230, February 2003