Nitrogen loss reduction by adding KH₂PO₄-K₂HPO₄ buffer solution during composting of sewage sludge

Area of Science:

• Environmental Science
• Waste Management
• Soil Science

Background:

• Nitrogen loss via ammonia emission is a significant challenge in sewage sludge composting.
• Effective nitrogen management is crucial for composting efficiency and environmental protection.

Purpose of the Study:

• To investigate the impact of different buffer solutions on nitrogen loss during sewage sludge composting.
• To evaluate the effectiveness of specific amendments in reducing gaseous nitrogen emissions.

Main Methods:

• Composting trials were conducted using three different buffer mixtures: MgSO4 + K3PO4 (Run A), K2SO4 + KH2PO4-K2HPO4 (Run B), and MgSO4 + KH2PO4-K2HPO4 (Run C).
• Nitrogen loss, ammonia emission, and organic matter degradation were quantified for each treatment.

Main Results:

• Run C demonstrated a significant reduction in ammonia loss (53.8% and 45.5%) and total nitrogen loss (61.2% and 67.1%) compared to Runs A and B.
• Organic matter degradation in Run C was 36.8%, indicating a slight improvement.
• The combination of MgSO4 and KH2PO4-K2HPO4 effectively maintained pH for struvite precipitation and ammonia retention.

Conclusions:

• The addition of MgSO4 and KH2PO4-K2HPO4 is an effective strategy to minimize nitrogen loss during sewage sludge composting.
• This amendment promotes ammonia retention and enhances struvite formation, contributing to nutrient recovery.