Cost and Greenhouse Gas Emissions for a 220 mgd Facility to Attain 2 mg/L TN and 0.16 mg/L TP

摘要

The Colorado Department of Public Health and Environment (CDPHE) recently proposed longtermnutrient quality goals of 2.0 milligrams of nitrogen per liter (mg-N/L) for total nitrogen(TN) and 0.16 milligrams of phosphorus per liter (mg-P/L) for total phosphorus (TP) for warmwater streams in Colorado. The proposed regulatory initiatives will be considered by theColorado Water Quality Control Commission at an upcoming rule-making hearing. To supporttestimony that the Metro Wastewater Reclamation District (Metro District) will present at thathearing, a Nutrient Quality Impact Report was prepared to quantify the cost and greenhouse gas(GHG) emissions associated with upgrading the Robert W. Hite Treatment Facility (RWHTF) toprovide four levels of TP and three levels of TN reduction. The costs and GHG emissionsassociated with treatment to 2 mg/L TN are disproportionately high. Even if economic costs arenot considered, it can be argued the power and chemical consumption, and resulting GHGemissions, are excessive for the marginal benefits that may be gained, and could result in anegative net environmental impact.