A degradation model for high kitchen waste content municipal solid waste

Area of Science:

• Environmental Science
• Biotechnology
• Chemical Engineering

Background:

• Municipal solid waste (MSW) in developing nations typically contains high levels of kitchen waste (KW), leading to significant water and organic content.
• Existing anaerobic degradation models are often inadequate for simulating high KW content MSW due to their development based on low KW MSW from developed countries.

Purpose of the Study:

• To present a novel two-stage anaerobic degradation model specifically designed for high KW content MSW.
• To incorporate the degradation of key organic compounds like hollocellulose, sugars, proteins, and lipids into the model.
• To account for the inhibitory effects of volatile fatty acids (VFA) and pH on the degradation process.

Main Methods:

• Categorizing waste components into rapidly and slowly degradable groups based on degradation rates under optimal water conditions.
• Integrating the consideration of un-ionized VFA inhibition on hydrolysis/acidogenesis and methanogenesis.
• Including pH inhibition of methanogenesis within the model framework.
• Validating the model using laboratory experiments with both low and high KW content MSW.

Main Results:

• The proposed model accurately simulates the degradation of high KW content MSW, aligning well with experimental data.
• Under low VFA conditions, pH inhibition is the primary factor affecting methanogenesis.
• Under high VFA concentrations, both hydrolysis/acidogenesis and methanogenesis are significantly inhibited by un-ionized VFA.
• The model predicts that high KW MSW releases its gas potential more rapidly than low KW MSW under favorable conditions.

Conclusions:

• The developed two-stage anaerobic degradation model provides a robust tool for predicting the behavior of high KW content MSW.
• The model highlights the differential impacts of VFA and pH on anaerobic digestion based on concentration levels.
• This research offers improved simulation capabilities for waste management strategies in developing countries with high KW fractions in their MSW.