Excellent anammox performance driven by stable partial denitrification when encountering seasonal decreasing...

Area of Science:

• Environmental Microbiology
• Water Treatment Engineering

Background:

• Seasonal temperature reductions challenge wastewater treatment systems relying on partial anammox technology.
• Effluent quality deterioration is a significant concern in such systems.

Purpose of the Study:

• To investigate the relationship between denitrification and anammox processes under decreasing temperatures.
• To evaluate the stability and contribution of anammox in an anoxic moving bed biofilm reactor (MBBR) during temperature fluctuations.

Main Methods:

• Utilized an anoxic moving bed biofilm reactor (MBBR) to simulate temperature decrease effects.
• Employed high-throughput sequencing to analyze microbial community composition.
• Used quantitative PCR (qPCR) to assess the abundance of key functional genes.

Main Results:

• Decreasing temperatures inhibited nitrite reduction to nitrogen gas, favoring nitrite availability for anammox.
• Anammox bacteria were enriched, increasing from 0.56% to 1.22% relative abundance.
• The anammox contribution to total nitrogen removal remained high (91.3% ± 6.6%) and even increased, despite a slight decrease in total inorganic nitrogen removal.

Conclusions:

• The partial denitrification/anammox process in anoxic MBBRs demonstrates resilience to temperature decreases.
• This process can maintain stable autotrophic nitrogen removal, offering a viable strategy for mainstream anammox applications in variable climates.