GREENHOUSE GAS (N2O, CH4 AND CO2) EMISSIONS FROM THE STICKNEY WATER RECLAMATION PLANT, STICKNEY, IL (USA)

The Stickney Water Reclamation Plant (SWRP) is among the world's largest, treating approximately 4.6 million cubic meters of wastewater per day and serving 2.4 million people. During the period August-November 2008, 55 gas samples were collected at the SWRP for a reconnaissance study of greenhouse gas emissions from the different treatment processes. Gaseous emissions from the aerated grit chambers, preliminary settling tanks, Imhoff tanks, aeration batteries, final settling tanks, anaerobic digesters, biosolids piles, and several plant exhausts were analyzed by gas chromatography to determine N₂O, CH₄, and CO₂ concentrations and fluxes. In addition, nine samples of ambient air were collected along the plant's perimeter in the early morning during a temperature inversion. Upper limits of measured fluxes from different parts of the plant are estimated at 3.61x10⁶ kg/y, 6.45x10⁵ kg/y, and 8.71x10⁸ kg/y for N₂O, CH₄, and CO₂, respectively. For all gases, the aeration batteries produce the highest fluxes. Estimated total fluxes from the SWRP for these three gas species are 3.81x10⁶, 3.95x10⁶, and 9.48x10⁸ kg/y. Theoretical total fluxes of N₂O and CO₂ calculated according to the Intergovernmental Panel on Climate Change (IPCC) and the National Association of Clean Water Agencies (NACWA) models are on the order of 10³ and 10⁶ kg/y for N₂O and CO₂, respectively, much lower than estimated values based on our reconnaissance measurements.