Assessment of greenhouse gas emissions in delhi landfills: analyzing factors affecting emissions and environmental implications

Landfills are a primary method of waste disposal in developing nations despite their environmental impact. The decomposition of municipal organic waste in landfills generates potent greenhouse gases (GHGs) that contribute to the effects of urban climate change. In Delhi, India, which generates 11,144 tons per day (TPD) of municipal solid waste (MSW), three major landfill sites Ghazipur (GL), Bhalswa (BL), and Okhla (OL) were examined using the well-established in-situ static chamber method to measure emissions of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). This study highlights the need to address these uncertainties by comprehensively capturing GHG emissions from the diverse dynamics within the landfill through rigorous field experiments that account for spatial and temporal variability. The average CH4 emission fluxes from three years of extensive field studies exhibited high variability, measured at 1494 +/- 893 (CV = 59.8%), 1576 +/- 746 (CV = 47.3%), and 961 +/- 322 (CV = 33.5%) mg m-2 h-1 for GL, BL, and OL, respectively. This resulted in CH4 emission factors (EFs) of 5.6 +/- 3.5, 4.4 +/- 1.9, and 4.2 +/- 1.4 g kg-1 for GL, BL, and OL, respectively. The CO2 emission fluxes were 7520 +/- 3401 (CV = 45.2%), 8005 +/- 3907 (CV = 48.8%), and 5066 +/- 1985 (CV = 39.2%) mg m-2 h-1 with corresponding EFs of 20.0 +/- 7, 23.3 +/- 9, and 16.3 +/- 4.7 g kg-1. The N2O emission fluxes were 1210 +/- 329 (CV = 27.2%), 998 +/- 298 (CV = 30%) and 944 +/- 339 (CV = 36%) mu g m-2 h-1 with EFs of 3.8 +/- 0.1, 2.5 +/- 0.2, and 3.1 +/- 0.3 mg kg-1 for GL, BL, and OL, respectively. Total GHG emissions from Delhi's landfills were estimated as 328.6 +/- 91.9, 231.0 +/- 109.5, and 241.1 +/- 112.2 Gg CO2 equivalent for 2009-10, 2010-11, and 2011-12. Investigating waste management practices such as spreading, covering, and compaction is essential for understanding their impact on GHG emissions and advancing climate change mitigation through waste-to-energy solutions for sustainable solid waste management and energy production. While the findings offer valuable understandings into emission patterns, the limited sample size introduces some uncertainty, and the EFs should be considered as a preliminary estimation of major GHG in three consecutive years. Future research is necessary to validate these factors with more extensive datasets that capture spatial and seasonal variations in emissions.