Impact of nitrate-enhanced leachate recirculation on gaseous releases from a landfill bioreactor cell

• Published in: Waste management (Elmsford) 2009-07, Vol.29 (7), p.2078-2084
• Main Authors: Tallec, G., Bureau, C., Peu, P., Benoist, J.C., Lemunier, M., Budka, A., Presse, D., Bouchez, T.
• Format: Article
• Language: English
• Subjects: Applied sciences; Atmospheric pollution; Bioreactors; CARBON DIOXIDE; Carbon Dioxide - analysis; Chambers; Collection; Detectors; Devices; ELECTRON-CAPTURE DETECTORS; Environmental Sciences; Exact sciences and technology; Flame Ionization; General treatment and storage processes; LANDFILL GAS; Landfills; MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; METHANE; Methane - analysis; NITRATES; Nitrates - chemistry; NITROUS OXIDE; Nitrous Oxide - analysis; Nitrous oxides; Other wastes and particular components of wastes; Oxygen - analysis; Pollution; Raw; SANITARY LANDFILLS; Volatilization; Wastes
• ISSN: 0956-053X; 1879-2456
• DOI: 10.1016/j.wasman.2009.01.006

This study evaluates the impact of nitrate injection on a full scale landfill bioreactor through the monitoring of gaseous releases and particularly N 2O emissions. During several weeks, we monitored gas concentrations in the landfill gas collection system as well as surface gas releases with a series of seven static chambers. These devices were directly connected to a gas chromatograph coupled to a flame ionisation detector and an electron capture detector (GC-FID/ECD) placed directly on the field. Measurements were performed before, during and after recirculation of raw leachate and nitrate-enhanced leachate. Raw leachate recirculation did not have a significant effect on the biogas concentrations (CO 2, CH 4 and N 2O) in the gas extraction network. However, nitrate-enhanced leachate recirculation induced a marked increase of the N 2O concentrations in the gas collected from the recirculation trench (100-fold increase from 0.2 ppm to 23 ppm). In the common gas collection system however, this N 2O increase was no more detectable because of dilution by gas coming from other cells or ambient air intrusion. Surface releases through the temporary cover were characterized by a large spatial and temporal variability. One automated chamber gave limited standard errors over each experimental period for N 2O releases: 8.1 ± 0.16 mg m −2 d −1 ( n = 384), 4.2 ± 0.14 mg m −2 d −1 ( n = 132) and 1.9 ± 0.10 mg m −2 d −1 ( n = 49), during, after raw leachate and nitrate-enhanced leachate recirculation, respectively. No clear correlation between N 2O gaseous surface releases and recirculation events were evidenced. Estimated N 2O fluxes remained in the lower range of what is reported in the literature for landfill covers, even after nitrate injection.