An evaluation of substrate degradation patterns in the composting process. Part 2: temperature-corrected profiles

Area of Science:

• Environmental Science
• Biotechnology
• Bioreactor Engineering

Background:

• Substrate degradation profiles in composting are complex and influenced by various factors.
• Existing models often struggle to accurately represent the full spectrum of composting degradation patterns.
• Temperature is a critical factor affecting degradation rates, necessitating temperature correction for comparative analysis.

Purpose of the Study:

• To evaluate the applicability of single exponential, double exponential, and non-logarithmic Gompertz models for describing temperature-corrected composting substrate degradation profiles.
• To assess the common patterns observed in substrate degradation profiles from composting literature.
• To identify limitations of current models and suggest areas for future research.

Main Methods:

• Collected and temperature-corrected (to 40°C) 44 substrate degradation profiles from composting literature.
• Applied single exponential, double exponential, and non-logarithmic Gompertz models to the corrected data.
• Analyzed the goodness-of-fit for each model and identified common profile shapes (multi-phase, convex, sigmoidal).

Main Results:

• Multi-phase profiles were most common; sigmoidal patterns were rare.
• 33 out of 44 temperature-corrected datasets were poorly described by the tested models.
• The non-logarithmic Gompertz model showed the best performance, particularly in modeling the lag phase, but overall model applicability was limited.

Conclusions:

• Current exponential and Gompertz models have limited evidence for describing full, temperature-adjusted composting degradation profiles.
• Further research is needed to understand poorly modeled profiles and refine temperature correction methods.
• Future work should also incorporate corrections for moisture and oxygen variations.