Enhancing denitrification efficiency for nitrogen removal using waste sludge alkaline fermentation liquid as external...

Area of Science:

• Environmental Science
• Environmental Engineering
• Microbiology

Background:

• External carbon sources are typically added to improve nitrogen removal via denitrification in wastewater treatment.
• Investigating sustainable and cost-effective alternatives for carbon sources is crucial for wastewater treatment efficiency.

Purpose of the Study:

• To evaluate the efficacy of wastewater sludge alkaline fermentation liquid as an alternative carbon source for biological denitrification.
• To determine the optimal carbon-to-nitrogen ratios (C/N) and hydraulic retention times (HRTs) for enhanced denitrification performance.

Main Methods:

• Biological denitrification experiments were conducted using sludge alkaline fermentation liquid.
• Performance was assessed at various C/N ratios and HRTs.
• Dissolved organic matter composition was analyzed using excitation-emission matrix (EEM) spectroscopy with fluorescence regional integration (FRI).

Main Results:

• Optimal denitrification was achieved at a C/N of 7 and an HRT of 8 hours.
• A nitrate removal efficiency of 96.4% was attained with negligible nitrite accumulation.
• Volatile fatty acids (VFAs) were preferentially utilized over proteins and carbohydrates from the sludge source.

Conclusions:

• Wastewater sludge alkaline fermentation liquid is a viable and efficient alternative carbon source for biological denitrification.
• Optimal operational parameters (C/N=7, HRT=8h) promote high nitrate removal and efficient organic matter utilization.
• The study indicates potential for improved nitrogen removal and resource recovery in wastewater treatment processes.