Environmental Science & Technology
Published online 1 October 2021
https://pubs.acs.org/doi/10.1021/acs.est.1c02526

Received 18 April 2021
Accepted 15 September 2021
Yixuan Wang*, James W. Levis, and Morton A. Barlaz
Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Campus Box 7908, Raleigh, North Carolina 27695-7908, United States

Table of Contents

Abstract

The objective of this study is to develop an LCA model for a representative U.S. MSW landfill that is responsive to landfill size, regulatory thresholds for landfill gas (LFG) collection and control, practices for LFG management (i.e., passive venting, flare, combustion for energy recovery), and four alternative schedules for LFG collection well installation.

Synopsis

Construction and operation of landfills contribute to toxicity impacts, while the longevity of landfill gas collection contributes mostly to climate change impacts.

Introduction

  • The World Bank (2018) estimates that 70% of municipal solid waste (MSW) is disposed in landfills or open dumps globally.
  • 52% in the US.
  • Determinants of life-cycle modelling of landfills: time of waste disposal, landfill gas(LFG), and leachate generated; influence of regulations on collected LFGs; gas collection efficiency1; benefits of LFG; the annual mass of waste disposal and landfill sizes.
  • Innovations 1: Few LCA considered the impact from the capital goods(equipment, trucks, buildings, etc.) excluded some research in Europe.
  • Innovations 2: Regulation of LFG collection and control in the US is updating while no landfill models cover this gap.
  • Objectives of this study: 1. Develope a LCA model representing US MSW landfill that covers the LFG management. 2. Investigating the effects of gas collection and control regulations, landfill size and design, and waste composition on LFG emissions and overall landfill environmental performance.

Modelling Approach

Representative U.S. Landfill

U.S. EPA’s Landfill Methane Outreach Program (LMOP) database: covering 1108 landfills. Landfill properties include waste acceptance(Mg $yr^[-1]$), operating years, annual precipitation, LFG decay rate constant, and percent of waste received.

Material, Fuel, and Electricity Use

  • The environmental profile of materials extraction and production, as well as energy consumption, was developed from Ecoinvent v3.6.
  • Materials required for constructing a landfill, daily cover and other materials is measured.

Landfill Gas Generation, Collection, and Control

  • A first-order decay model is used to estimated the LFG generation rate.
  • Four gas collection scenarios were analysed, which are different in LFG collection efficiencies temporally.
  • Considering turn-on and -off times of gas collection system, uncollected CH4.

Leachate Generation, Collection, and Control

Life-Cycle Impact Assessment (LCIA)

  1. CH4 should be collected by the gas collection system of a landfill facility though some of them will be realised as the form of oxidation. This process is indicated by landfill gas collection efficiency. ↩︎