Composting Odour

Composting odour is a common nuisance issue at facilities that process organic waste (including food scraps, yard trimmings, and biosolids) through controlled biological decomposition. This process generates significant odours from volatile organic compounds and reduced sulfur species released as microorganisms break down organic matter.

Odour intensity and character at a composting facility vary with the stage of the process, the feedstock mix, and the aeration method used. Facilities near residential areas are frequently subject to odour complaints, making effective odour control and ambient monitoring an operational priority.

Major Sources of Composting Odour

• Active composting piles or windrows, where anaerobic pockets form and release hydrogen sulfide and ammonia
• Incoming feedstock receiving and storage areas, particularly for pre-decomposed or high-moisture material
• Turning and screening operations, which release trapped gases into the ambient air
• Leachate collection and storage ponds
• Curing piles in the later stages of stabilization

Key Contributing Factors

• Feedstock composition, particularly the ratio of nitrogen-rich to carbon-rich material
• Insufficient oxygen supply, leading to anaerobic conditions and hydrogen sulfide formation
• Excess moisture content, which promotes anaerobic pockets within piles
• Ambient temperature and wind conditions, which affect dispersion toward nearby receptors

Composting Odour Control Strategies

• Enclosed or in-vessel composting systems that contain process air for treatment
• Biofiltration of captured process air before release to atmosphere
• Proper pile turning frequency and aeration management to maintain aerobic conditions
• Moisture content management within the optimal range for aerobic decomposition
• Buffer zones and setback distances from sensitive receptors
• Ambient and fenceline odour monitoring to track performance and respond to complaints

See Also

• Biofilter, for the odour control technology commonly used to treat composting process air
• Volume Source, for how open piles and windrows are classified as a source type
• Active Source, for mechanically ventilated sources such as in-vessel composting systems
• Passive Sources, for open piles with weak, unforced airflow
• For further technical background, see Metro Vancouver’s Best Odour Management Practices at Composting Facilities report.