Reducing Emissions from Composting: Environmental and Economic Benefits – An Easy Comprehensive Summary

Composting is an effective way to manage organic waste, preventing it from ending up in landfills where it would generate methane, a powerful greenhouse gas. However, composting itself also releases greenhouse gases (GHGs) like methane (CH₄), nitrous oxide (N₂O), and carbon dioxide (CO₂), as well as air pollutants such as ammonia (NH₃) and volatile organic compounds (VOCs). The study by Nordahl et al. (2023) critically examines emissions from composting and explores ways to minimize environmental impact while maximizing economic benefits.

Why Composting Matters

• Environmental Benefits: Composting reduces landfill waste, decreasing methane emissions that contribute to climate change. It also recycles valuable nutrients into soil, improving soil fertility and reducing reliance on chemical fertilizers.

• Economic Benefits: Composting can create jobs in waste management and agriculture, save landfill space, and reduce municipal costs related to waste disposal.

Key Findings on Greenhouse Gas Emissions

• Methane (CH₄): Composting yard waste is the largest contributor to CH₄ emissions. However, turning compost piles frequently or using forced aeration significantly reduces CH₄ production.

• Nitrous Oxide (N₂O): For nitrogen-rich waste like manure and sewage sludge, N₂O emissions can be high. This is problematic because N₂O is nearly 300 times more potent than CO₂ in terms of global warming potential.

• Carbon Dioxide (CO₂): While CO₂ is naturally released during composting, it is part of the carbon cycle and is less concerning than CH₄ or N₂O.

Air Pollutants and Health Impacts

• Ammonia (NH₃): High NH₃ emissions contribute to air pollution and can cause respiratory issues. Composting methods that allow excess aeration may increase NH₃ emissions.

• Volatile Organic Compounds (VOCs): These emissions can lead to poor air quality and bad odors, affecting communities near composting facilities.

Best Practices for Low-Emission Composting

To balance the benefits of composting with the need to reduce emissions, the study suggests several strategies:

1. Use Anaerobic Digestion (AD) Before Composting: Treating organic waste in anaerobic digesters before composting can lower N₂O emissions by up to 80% and reduce odors.

2. Improve Composting Techniques:

   • Forced aeration reduces CH₄ emissions but may increase NH₃ emissions. A controlled approach is needed.

   • Adding bulking agents (e.g., wood chips) improves air circulation, reducing GHG production.

   • Covering compost piles or using biofilters can lower VOC and NH₃ emissions.

3. Optimize Waste Composition: Adjusting the carbon-to-nitrogen (C:N) ratio helps minimize both CH₄ and N₂O emissions.

4. Improve Policy and Regulation: Governments can incentivize low-emission composting practices and enforce standards that balance waste diversion with air quality concerns.

Economic and Environmental Benefits

• Lowering Costs for Waste Management: Efficient composting techniques reduce the need for landfill space, lowering waste disposal costs for cities.

• Enhancing Soil Quality: Compost improves soil fertility, reducing the need for synthetic fertilizers, which are expensive and have high carbon footprints.

• Job Creation: Expanding composting infrastructure creates employment opportunities in waste management, farming, and environmental services.

• Reducing Health Costs: By limiting air pollutants, improved composting methods can lower respiratory illnesses and associated healthcare expenses.

Conclusion

Composting is a powerful tool for waste management, but without proper techniques, it can contribute to climate change and air pollution. By implementing better aeration methods, using anaerobic digestion as a pre-treatment, and adjusting compost composition, emissions can be significantly reduced. These improvements will not only benefit the environment but also bring economic advantages by lowering waste management costs, improving soil health, and creating new job opportunities. Policymakers, businesses, and individuals must work together to ensure that composting remains a sustainable and beneficial practice.