A comparison of CH₄, N₂O and CO₂ emissions from three different cover types in a municipal solid waste landfill

ABSTRACT

High-density polyethylene (HDPE) membranes are commonly used as a cover component in sanitary landfills, although only limited evaluations of its effect on greenhouse gas (GHG) emissions have been completed. In this study, field GHG emission were investigated at the Dongbu landfill, using three different cover systems: HDPE covering; no covering, on the working face; and a novel material-Oreezyme Waste Cover (OWC) material as a trial material. Results showed that the HDPE membrane achieved a high CH₄ retention, 99.8% (CH₄ mean flux of 12 mg C m^-2 h^-1) compared with the air-permeable OWC surface (CH4 mean flux of 5933 mg C m^-2 h^-1) of the same landfill age. Fresh waste at the working face emitted a large fraction of N₂O, with average fluxes of 10 mg N m^-2 h^-2, while N₂O emissions were small at both the HDPE and the OWC sections. At the OWC section, CH₄ emissions were elevated under high air temperatures but decreased as landfill age increased. N₂O emissions from the working face had a significant negative correlation with air temperature, with peak values in winter. A massive presence of CO₂ was observed at both the working face and the OWC sections. Most importantly, the annual GHG emissions were 4.9 Gg yr^-1 in CO₂ equivalents for the landfill site, of which the OWC-covered section contributed the most CH₄ (41.9%), while the working face contributed the most N₂O (97.2%). HDPE membrane is therefore, a recommended cover material for GHG control.

Implications: Monitoring of GHG emissions at three different cover types in a municipal solid waste landfill during a 1-year period showed that the working face was a hotspot of N₂O, which should draw attention. High CH₄ fluxes occurred on the permeable surface covering a 1- to 2-year-old landfill. In contrast, the high-density polyethylene (HDPE) membrane achieved high CH₄ retention, and therefore is a recommended cover material for GHG control.

Acknowledgment

The authors acknowledge the staff at the Dongbu MSW landfills in Xiamen for the survey and sample collaboration.

Funding

This research was supported financially by the “Strategic Priority Research Program—Climate Change: Carbon Budget and Relevant Issues” of the Chinese Academy of Sciences (grant XDA05020602) and the National Natural Science Foundation of China (grant 41475130).

Additional information

Funding

This research was supported financially by the “Strategic Priority Research Program—Climate Change: Carbon Budget and Relevant Issues” of the Chinese Academy of Sciences (grant XDA05020602) and the National Natural Science Foundation of China (grant 41475130).

Notes on contributors

Xiaojun Wang

Xiaojun Wang, Xiangyu Lin, Ying Xu, and Xin Ye are research assistants at the Institute of Urban Environment, Chinese Academy of Sciences, in Xiamen, China.

Mingsheng Jia

Mingsheng Jia is a master’s student at the Institute of Urban Environment, Chinese Academy of Sciences, in Xiamen, China.

Xiangyu Lin

Xiaojun Wang, Xiangyu Lin, Ying Xu, and Xin Ye are research assistants at the Institute of Urban Environment, Chinese Academy of Sciences, in Xiamen, China.

Ying Xu

Xiaojun Wang, Xiangyu Lin, Ying Xu, and Xin Ye are research assistants at the Institute of Urban Environment, Chinese Academy of Sciences, in Xiamen, China.

Xin Ye

Xiaojun Wang, Xiangyu Lin, Ying Xu, and Xin Ye are research assistants at the Institute of Urban Environment, Chinese Academy of Sciences, in Xiamen, China.

Chih Ming Kao

Chih Ming Kao is a research professor at the Institute of Environmental Engineering, National Sun Yat-Sen University, in Kaohsiung, Taiwan.

Shaohua Chen

Shaohua Chen is a research professor at the Institute of Urban Environment, Chinese Academy of Sciences, in Xiamen, China.