Ithaca Area Wastewater Treatment Facility (IAWWTF) Tertiary Treatment Upgrades Before/After Impact Study: Effluent and Lake Phosphorus Results

The results of the IAWWTF tertiary treatment upgrade were analyzed by geostatistical analysis and Before/After impact studies. In May 2006, a tertiary treatment process was added to the IAWWTF treatment process. This upgrade has had a significant and positive effect on both the performance of the plant and on the water quality of southern Cayuga Lake. The effluent total phosphorus concentration decreased 58.7% after the upgrade, from an average of 0.424 mg/L to 0.175 mg/L. The effluent phosphorus load also decreased significantly, from 23.8 Lb/day to 9.83 Lb/day after the upgrade.In 2005, the average total phosphorus concentration in the south portion of Cayuga Lake was 40.0 micrograms per liter (μg/L). After the upgrade, the average was 29.0 μg/L, a decrease of 40%. The effluent and lake sampling data was statistically robust to detect a 58.7% and 40.0% reduction, respectively, at 2a = 0.05 and a power goal of 0.95 (Error type II = 0.05).