Aerobic composting with hydrothermal carbonization aqueous phase conditioning: Stabilized active gaseous nitrogen...

Area of Science:

• Environmental Science
• Soil Science
• Microbiology

Background:

• Reactive gaseous nitrogen (N) losses, including ammonia (NH3) and nitrous oxide (N2O), are significant environmental concerns during composting.
• The influence of hydrothermal carbonization aqueous phase (HAP) on compost N emissions and its mechanisms are not well understood.

Purpose of the Study:

• To investigate the effects of HAP and modified HAP (MHAP) on gaseous N emissions (NH3 and N2O) from chicken manure compost.
• To explore the underlying mechanisms, including changes in compost properties and bacterial communities, influenced by HAP application.

Main Methods:

• Quercus acutissima leaves-derived HAP and MHAP were added to chicken manure compost at 5% and 10% (w/w) application rates.
• Measurements included NH3 and N2O fluxes, compost physicochemical properties, and bacterial community composition.
• Statistical analysis was used to determine the influence of environmental factors and bacterial diversity on gaseous N emissions.

Main Results:

• High application rates of HAP significantly reduced cumulative NH3 volatilization by 23-26% compared to the control.
• Compost temperature and inorganic N concentrations were key factors influencing NH3 and N2O emissions.
• HAP and MHAP at high rates decreased the relative abundance of Bacteroidota and Proteobacteria, altering bacterial communities.

Conclusions:

• HAP application, particularly at high rates, is an effective strategy for reducing NH3 and N2O emissions from composting.
• Compost environmental factors and bacterial diversity play dominant roles in regulating gaseous N emissions.
• Findings support the rational utilization of HAP for mitigating gaseous N emissions in poultry manure composting.