Modeling organic micro pollutant degradation kinetics during sewage sludge composting

Area of Science:

• Environmental Science
• Environmental Chemistry
• Waste Management

Background:

• Organic micro-pollutants pose risks in sewage sludge.
• Composting is a common sludge treatment method.
• Understanding pollutant degradation kinetics is crucial for effective treatment.

Purpose of the Study:

• To investigate the degradation of 13 organic micro-pollutants in sewage sludge during aerobic composting.
• To evaluate the suitability of single and dual first-order kinetic models for describing micro-pollutant degradation.
• To determine the influence of composting temperature on degradation kinetics.

Main Methods:

• Aerobic composting of sewage sludge with 13 organic micro-pollutants over 52 days.
• Experimentation at 5 different composting temperatures.
• Application and comparison of single and dual first-order kinetic models.

Main Results:

• Both kinetic models described degradation well, with the dual first-order model showing higher accuracy.
• Average degradation coefficients were 0.025 d⁻¹ (single model) and 0.066 d⁻¹ (early) / 0.022 d⁻¹ (late) (dual model).
• Degradation was approximately three times faster in the initial 7 days compared to the later 45 days.
• Single first-order and late-stage dual first-order constants peaked at 35-65°C, while early-stage constants were temperature-independent.

Conclusions:

• The dual first-order model accurately represents micro-pollutant degradation during aerobic composting.
• Optimal degradation occurs within a specific temperature range (35-65°C) for later stages.
• Rapid initial degradation highlights the importance of early composting phases for micro-pollutant removal.