Partial nitrification using aerobic granules in continuous-flow reactor: rapid startup

Area of Science:

• Environmental Engineering
• Microbiology
• Wastewater Treatment

Background:

• Partial nitrification is a crucial step in wastewater treatment for nitrogen removal.
• Achieving rapid startup of partial nitrification in continuous-flow reactors remains a challenge.
• Aerobic granules offer a promising platform for stable microbial community development.

Purpose of the Study:

• To develop and evaluate a novel strategy for the rapid startup of partial nitrification in a continuous-flow reactor.
• To enrich specific microbial communities, including ammonia-oxidizing bacteria, within aerobic granules.
• To achieve high partial nitrification efficiency in a significantly reduced timeframe.

Main Methods:

• Cultivation of mature aerobic granules in a sequencing batch reactor with high chemical oxygen demand.
• Enrichment of structural stability-enhancing bacteria, such as Pseudoxanthomonas mexicana, within the granules.
• Incubation of granules in a continuous-flow reactor with stepwise reduction of influent chemical oxygen demand and subsequent bicarbonate addition.

Main Results:

• Successful enrichment of ammonia-oxidizing bacteria, Nitrosomonas europaea, within the incubated granules.
• Achieved a stable partial nitrification efficiency of 85-90% starting from day 36.
• Harvested partial nitrification granules after 52 days, demonstrating a significantly shorter startup period.

Conclusions:

• The novel strategy effectively accelerates the startup of partial nitrification in continuous-flow reactors.
• Aerobic granules are a robust carrier for establishing functional microbial communities for efficient nitrogen removal.
• This method presents a more time-efficient alternative for practical wastewater treatment applications.