[Partial Nitrification Fast Start-up and Stable Performance of 15℃ SBBR]

Area of Science:

• Environmental microbiology
• Wastewater treatment engineering

Context:

• Partial nitrification is a key process in wastewater treatment for nitrogen removal.
• Optimizing start-up and stable performance is essential for practical application.
• The influence of carbon-to-nitrogen (C/N) ratio on partial nitrification at low temperatures (15°C) requires further investigation.

Purpose:

• To investigate the effects of controlled C/N ratios on the fast start-up and stable performance of the partial nitrification process.
• To determine the optimal C/N ratio for successful partial nitrification initiation and operation.
• To understand the microbial community dynamics, specifically the role of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB), under different C/N conditions.

Summary:

• Controlled C/N ratios significantly impact the initiation and stability of partial nitrification in a Sequenced Batch Biofilm Reactor (SBBR) at 15°C.
• A C/N ratio of 1.5 facilitated fast initiation and stable operation by promoting ammonia oxidizing bacteria (AOB) dominance, while a C/N ratio of 0/3 led to process failure.
• Partial nitrification can be achieved without a carbon source, but appropriate carbon addition improves performance and stability. High dissolved oxygen (DO) and residual ammonium concentrations were key to stable operation and NOB repression.

Impact:

• Provides insights into optimizing partial nitrification for efficient nitrogen removal in wastewater treatment.
• Demonstrates the importance of C/N ratio control for successful process start-up and stable performance, particularly at low temperatures.
• Highlights the role of microbial community structure and operational parameters (DO, ammonium) in achieving stable partial nitrification for sidestream and mainstream wastewater applications.