Calculator tool for determining greenhouse gas emissions for biosolids processing and end use

Area of Science:

• Environmental Science
• Waste Management
• Climate Change Mitigation

Background:

• Biosolids management is a significant source of greenhouse gas (GHG) emissions.
• Municipalities require tools to accurately estimate these emissions for effective mitigation strategies.
• Existing methods for biosolids management vary widely in their environmental impact.

Purpose of the Study:

• To develop and validate a GHG calculator tool, the Biosolids Emissions Assessment Model (BEAM).
• To enable Canadian municipalities to estimate GHG emissions associated with different biosolids management pathways.
• To identify management practices with the lowest and highest GHG footprints.

Main Methods:

• The BEAM tool was developed using data from peer-reviewed literature and Canadian municipal programs.
• GHG emissions were modeled for biosolids processing, end use, and disposal.
• Emissions from nine existing Canadian biosolids management programs were estimated using the BEAM model.

Main Results:

• Combustion after dewatering resulted in the highest GHG emissions.
• Digestion followed by land application showed the lowest emissions (-26 and -23 Mg CO(2)e 100 Mg(-1) biosolids dry wt.).
• Transportation contributed minimally to overall emissions, while N(2)O from land application and processing represented key uncertainties.

Conclusions:

• The BEAM model provides a valuable tool for municipalities to assess GHG emissions from biosolids.
• Targeted biosolids use and process optimization, particularly to avoid CH(4) and N(2)O, can lead to substantial GHG reductions.
• Further research is needed to reduce uncertainties in N(2)O emission estimations.