Woodcache PBC

Wood Biodegradation in Laboratory-Scale Landfills

Xiaoming Wang, Jennifer M. Padgett, Florentino B. De la Cruz, Morton Barlaz
Environmental Science & Technology
Peer Reviewed: Yes
Year Published: 2011

Key Takeaways:

  • There was a significant difference in methane generation between hardwood and softwood species, even though cellulose concentrations were similar.
  • This may be because lignin polymers in hardwood species have lower structural integrity and are typically more easily degraded in chemical processes than softwood lignin.
  • Hardwoods contain both syringyl and guaiacl lignin units, while softwoods contain only guaiacyl lignin.
Wood degradation in laboratory scale landfills
This entry is part 4 of 6 in the series Do Wood Vaults Really Work?

Abstract

The objective of this research was to characterize the anaerobic biodegradability of major wood products in municipal waste by measuring methane yields, decay rates, the extent of carbohydrate decomposition, carbon storage, and leachate toxicity. Tests were conducted in triplicate 8 L reactors operated to obtain maximum yields. Measured methane yields for red oak, eucalyptus, spruce, radiata pine, plywood (PW), oriented strand board (OSB) from hardwood (HW) and soft-wood (SW), particleboard (PB) and medium-density fiber-board (MDF) were 32.5, 0, 7.5, 0.5, 6.3, 84.5, 0, 5.6, and 4.6 mL CH4 dry g1, respectively. The red oak, a HW, exhibited greater decomposition than either SW (spruce and radiata), a trend that was also measured for the OSB-HW relative to OSB-SW. However, the eucalyptus (HW) exhibited toxicity. Thus, wood species have unique methane yields that should be considered in the development of national inventories of methane production
and carbon storage. The current assumption of uniform biodegradability is not appropriate. The ammonia release from urea formaldehyde as present in PB and MDF could contribute to ammonia in landfill leachate. Using the extent of carbon conversion measured in this research, 019.9%, predicted methane production from a wood mixture using the Intergovernmental Panel for Climate Change waste model is only 7.9% of that predicted using the 50% carbon conversion default.