Mass balance analysis on the behavior of major elements disposed at a waste landfill site

Understanding the behavior of major elements in landfill is necessary for effective landfill site management. However, there have been no established methods to study the mass balance of major landfill elements, excluding some studies focused on specific target materials. In this study, different landfill management methodologies were used to conduct mass balance analysis of three major elements at Sudokwon Landfill Site 2 (LS2) in South Korea during 2001-2014. The results indicated that biochemically decomposable carbon accounted for 38.2% of the total landfill organic carbon content. Further, 51.3% of this decomposable fraction underwent decomposition during the research period, 99.0% of which was emitted in landfill gas as CO₂ and CH₄. In terms of sulfur, 6.1% of the total decomposed sulfur was emitted as H₂S (97.0%), and almost all of the total decomposed nitrogen was emitted (5.7%) in leachate as NH₄⁺-N. LS2 had a low decomposition rate due to the dryness of the landfill site and the increasing ratio of demolition waste, which does not decompose easily. Therefore, thermochemical energy recovery before waste disposal and leachate recycling seem to be necessary. In terms of leachate recycling, economic measures to prevent nitrogen accumulation may be required in the long term. Additionally, for suppressing H₂S generation, separate disposal of waste soil produced throughout the course of mechanical pretreatment of demolition waste should be conducted.