Pile settlement and volume reduction measurement during forced-aeration static composting

Area of Science:

• Environmental Science
• Waste Management
• Soil Science

Background:

• Composting is a vital process for organic waste recycling.
• Understanding compost pile settlement is crucial for optimizing aeration and managing volume.
• Previous research has not fully detailed the multi-stage settlement dynamics and influencing factors.

Purpose of the Study:

• To quantify settlement in composting piles using a specialized device.
• To analyze the time-dependent settlement velocity, bulk density, and effective bulk density.
• To investigate the impact of different bulking agents on compost settlement.

Main Methods:

• Utilized a settlement measurement device to monitor compost layers over time.
• Differentiated settlement into physical compressive and mass loss stages.
• Applied the formula rho'=Ah(B) to describe bulk density and pile height at the end of compressive settlement.
• Compared the physical compressibilities of various composting mixtures.

Main Results:

• Composting settlement comprises distinct physical compressive and mass loss phases.
• The relationship between bulk density (rho') and pile height (h) follows rho'=Ah(B) after compressive settlement.
• Composting mixtures containing night-soil sludge and garden refuse (1:1) exhibited the highest physical compressibility.
• Appropriate addition of bulking agents effectively slowed down settlement, with bark proving superior to cornstalk.

Conclusions:

• Compost pile settlement is a two-stage process influenced by material composition and bulking agents.
• Bulking agents play a significant role in mitigating settlement, enhancing compost pile stability and management.
• Bark is a more effective bulking agent than cornstalk for reducing compost settlement.