Optimum moisture levels for biodegradation of mortality composting envelope materials

Area of Science:

• Environmental Microbiology
• Solid-State Fermentation Science

Background:

• Moisture is a critical factor influencing the physical and biological properties of composting materials.
• Aerobic microbial respiration rates (oxygen uptake and carbon dioxide evolution) vary with moisture content and material composition.

Purpose of the Study:

• To measure and compare microbial respiration rates of 12 different mortality composting envelope materials across various moisture levels.
• To identify materials with high respiration potential for enhanced mortality composting.
• To determine the optimal moisture content for maximizing microbial respiration in different composting materials.

Main Methods:

• Microbial respiration rates were measured using a pressure sensor method.
• Measurements were conducted on 12 distinct composting envelope materials at six different moisture levels.
• Respiration rates were quantified in terms of oxygen uptake and carbon dioxide evolution (mg O2/g VS-day).

Main Results:

• A broad spectrum of respiration rates (1.6–94.2 mg O2/g VS-day) was observed among the materials.
• Alfalfa hay, silage, oat straw, and turkey litter exhibited the highest respiration rates.
• Optimal moisture content for maximum respiration generally occurred near the water holding capacity (60–80% w.b.), with an exception for a soil compost blend (around 25% w.b.).

Conclusions:

• Specific materials like alfalfa hay, silage, oat straw, and turkey litter are promising for improving temperature and pathogen destruction in mortality composting.
• Understanding optimal moisture content is crucial for effective moisture management and process control in composting.
• The findings provide valuable insights for optimizing mortality composting strategies to enhance efficiency and pathogen reduction.