Regulating bacterial dynamics by lime addition to enhance kitchen waste composting

Area of Science:

• Environmental Microbiology
• Waste Management
• Biotechnology

Background:

• Kitchen waste composting generates greenhouse gases and ammonia, impacting environmental quality.
• Bacterial community dynamics are crucial for efficient composting and nutrient cycling.
• Lime addition is explored as a strategy to mitigate emissions and improve compost performance.

Purpose of the Study:

• To investigate the effects of lime addition on bacterial community structure and function during kitchen waste composting.
• To elucidate the mechanisms by which lime influences composting stages and reduces emissions.
• To assess the overall impact of lime on biotic and abiotic composting parameters.

Main Methods:

• Modular network analysis was employed to study bacterial community dynamics.
• Lime was added at 1% and 1.5% (wet weight) during different composting stages.
• Key parameters such as pH, temperature, and emissions (greenhouse gases, ammonia, nitrous oxide) were monitored.

Main Results:

• Lime addition shifted bacterial communities into three distinct modules corresponding to mesophilic, thermophilic, and mature stages.
• At 1% lime, acidogens and denitrifiers were suppressed in the mesophilic stage, reducing greenhouse gas emissions.
• Lime increased pH and temperature, favoring thermophilic bacteria for lignocellulose biodegradation and enriched nitrifiers in the mature stage, decreasing nitrous oxide emissions.

Conclusions:

• Lime addition effectively modulates bacterial communities to enhance kitchen waste composting.
• Optimized lime application (1-1.5%) mitigates harmful emissions and promotes efficient biodegradation and nutrient formation.
• Lime improves both microbial activity and environmental conditions, leading to superior compost quality.