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ODOR CONTROL STUDY processes . To test the operator' s observations , odor and sulfur mass emissions were calculated for the Filtrate Equalization Basin and the liquid treatment processes , with and without filtrate . At the time of the sampling program , the Filtrate Equalization Basin had been eliminated , following a recommendation by PBS &J during the site visit in April . Therefore , in order to assess the impact of eliminating the Filtrate Equalization Basin , odor and sulfur flux rates were measured in the Filtrate Sump and mass emission rates were calculated using the flux rate applied over the area of the Filtrate Equalization Basin . This assessment showed that eliminating the Filtrate Equalization Basin had eliminated approximately 1 . 7 pounds of sulfur per day. Odor and sulfur emission rates were also calculated for the Anoxic Tank and the Oxidation Ditches . Odor and sulfur measurements were taken in the Anoxic Tank and the pre-oxygen zone and mixed-aerated zone of the oxidation ditch , prior to and after the introduction of filtrate. The different zones of the oxidation ditch were sampled in order to obtain representative air samples for areas with different aeration patterns . Unfortunately, the night before the sampling program , the return activated sludge (RAS ) pumps failed and did not become operational until 8 : 50 am the day of sampling . The RAS pumps are used to deliver fresh biological microbes to the Anoxic Tanks as part of the liquid treatment process . Since the RAS pumps did not work, the Anoxic Tank appeared to contain only raw wastewater. The lack of return activated sludge allowed the contents of the Anoxic Tank to become somewhat septic and this affected the quality of the influent wastewater to the oxidation ditch . This degradation in raw wastewater appears to have affected the emission rates for all the liquid treatment process . Figures 9 and 10 show that the morning samples (which did not contain filtrate) had higher odor and sulfur emissions than the afternoon samples . Thus , the sampling program did not confirm the operator' s observations . Problems with the return activated sludge pumps appear to have prevented the sampling program from discovering the impact of filtrate on liquid process emissions . However, based on the very low emissions from the oxidation ditch (even under bad influent conditions ) , filtrate in not likely to impact emissions from the oxidation ditches . Overall , calculations indicate that the the oxidation ditch contributes only 0 . 5 % of the total emissions from the Central WWTF . However, the impact of filtrate on Anoxic Tank emissions remains unknown at this time . 2 . 3 . 5 Impact of Recent Improvements on Emissions As indicated above , the Filtrate Equalization Basin had been eliminated at the time of sampling and this eliminated an estimated 1 . 7 pounds of sulfur per day compared to operations in April 2002 . Operators at the plant also eliminated the Aerobic Digesters and . the construction of hoods and covers in the belt filter press area of the Dewatering Building were about to be completed . In order to assess the impact of these 12 Indian River County, Central Wastewater Treatment Facility PBSU #071230, February 2003