Estimation of waste component-specific landfill decay rates using laboratory-scale decomposition data

Area of Science:

• Environmental Engineering
• Waste Management Science
• Biogeochemistry

Background:

• Current U.S. EPA models treat municipal solid waste (MSW) as homogeneous, using a single decay rate.
• This simplification limits accurate assessment of how waste composition impacts methane generation.

Purpose of the Study:

• To develop component-specific decay rates for major biodegradable MSW components.
• To evaluate the impact of waste diversion programs on methane production using these new rates.

Main Methods:

• Derived field-scale decay rates (k(field)) from laboratory-scale rate constants (k(lab)) for individual MSW components.
• Assumed the average of weighted field-scale decay rates equals the bulk MSW decay rate.
• Modeled methane production reductions based on 100% diversion of yard and food waste.

Main Results:

• Estimated component-specific field-scale decay rates (e.g., grass: 0.298 yr(-1), food waste: 0.144 yr(-1)).
• 100% diversion of yard and food waste reduced year 20 methane production by 45%.
• Food waste diversion most impacted collectable methane at years 10-20; paper diversion at year 40.

Conclusions:

• Component-specific decay rates offer a more accurate approach to modeling MSW methane generation.
• Landfill waste diversion programs, particularly for food and yard waste, are effective in reducing methane emissions.
• Understanding component decay dynamics is crucial for optimizing landfill management and gas collection strategies.