Thermal pretreatment-enhanced partial denitrification/anammox: Mobilising in-situ dissolved organic carbon to improve nitrogen removal in municipal wastewater

Area of Science:

• Environmental Science
• Environmental Engineering
• Microbiology

Background:

• Low carbon-to-nitrogen ratio hinders efficient nitrogen removal in municipal wastewater via partial denitrification/anammox (PD/A).
• Utilizing in-situ carbon sources is crucial for optimizing biological nutrient removal processes.

Purpose of the Study:

• To investigate the effectiveness of thermal pretreatment for enhancing PD/A performance by utilizing in-situ carbon.
• To understand the impact of thermal pretreatment on microbial communities and organic matter composition.

Main Methods:

• Municipal wastewater was subjected to thermal pretreatment at 100°C for 30 minutes.
• Changes in soluble chemical oxygen demand (sCOD)/NO3--N ratio were measured.
• Nitrogen removal efficiency was monitored during long-term PD/A operation.
• Microbial community composition and functional gene abundance were analyzed.

Main Results:

• Thermal pretreatment significantly increased the sCOD/NO3--N ratio, enhancing nitrogen removal efficiency by 12±7%.
• The process promoted the release of tyrosine-like proteins and humic acid-like substances, facilitating denitrification.
• Key denitrifiers and carbon metabolism-related genes were enriched, indicating a shift in microbial function.

Conclusions:

• Thermal pretreatment is a viable strategy to enhance in-situ carbon utilization for improved nitrogen removal in PD/A processes.
• This approach offers a sustainable alternative to external carbon addition for municipal wastewater treatment.
• Findings provide theoretical guidance for optimizing PD/A applications in wastewater treatment plants.