Physical modelling of the composting environment: a review. Part 2: Simulation performance

Area of Science:

• Environmental Science and Engineering
• Biotechnology
• Waste Management

Background:

• Composting reactors are crucial for waste management, but scaling up from laboratory to full-scale systems presents challenges.
• Understanding heat balance and temperature profiles is essential for efficient composting and pathogen reduction.

Purpose of the Study:

• To review and evaluate heat balance data from experimental and full-scale composting reactors.
• To assess the simulation performance of laboratory and pilot-scale reactors against full-scale temperature profiles.
• To identify key factors influencing the accuracy of composting simulations.

Main Methods:

• Literature review of published heat balance data for composting reactors.
• Quantitative and qualitative analysis of temperature profile characteristics from laboratory, pilot, and full-scale systems.
• Comparison of heat loss (ventilative and CCR) and temperature-time integral parameters across different scales.

Main Results:

• Laboratory reactors exhibit significantly higher ventilative (36-67%) and conductive/convective/radiative (CCR) heat losses (33-62%) compared to full-scale systems (ventilative 70-95%, CCR 3-15%).
• Full-scale windrow and forced aeration systems show higher temperature integrals (A(40), A(55)) and longer durations at target temperatures than laboratory systems.
• Pilot-scale reactors with moderate insulation and low aeration rates closely replicated full-scale temperature profiles, unlike those with high aeration.

Conclusions:

• Laboratory-scale composting simulations often do not accurately reflect full-scale heat dynamics due to differences in heat loss.
• Controlling aeration rates and minimizing CCR heat losses are critical for accurate simulation of composting environments.
• Optimized pilot-scale reactors can serve as effective models for full-scale composting process development and research.