Assessment of nitrification process in a sequencing batch reactor: Modelling and genomic approach

Area of Science:

• Environmental microbiology
• Water treatment technologies
• Biogeochemical cycles

Background:

• Nitrification is key for removing ammoniacal nitrogen from wastewater.
• Sequencing batch reactors (SBRs) are versatile for biological wastewater treatment.
• Understanding microbial communities is crucial for optimizing nitrogen removal processes.

Purpose of the Study:

• To evaluate the efficiency of nitrification in a lab-scale SBR.
• To identify key bacterial taxa involved in nitrogen transformation.
• To develop a kinetic model for predicting nitrogen compound transformations.

Main Methods:

• Lab-scale sequencing batch reactor (SBR) operation.
• Analysis of nitrogen compounds (N-NH4+, N-NO2-, N-NO3-).
• Volatile suspended solids (VSS) concentration measurement.
• Bacterial community analysis using 16S rRNA sequencing and FAPROTAX.
• Kinetic modeling of nitrogen and carbon transformations.

Main Results:

• Achieved 96% removal of ammoniacal nitrogen and 73% formation of nitrate.
• Established a strong linear correlation between VSS concentration and nitrate formation (r² = 0.9978).
• Identified diverse bacterial communities, including Nitrospira and Nitrosomonas, crucial for nitrification.
• Kinetic model accurately predicted nitrogen and carbon transformations.
• Higher biomass concentration reduced nitrogen oxidation rates but increased denitrification.

Conclusions:

• SBRs are effective for nitrification, with efficiency linked to biomass concentration.
• Bacterial genera Nitrospira and Nitrosomonas play vital roles in the observed nitrification.
• Biomass concentration influences both nitrification and denitrification rates.
• The developed kinetic model provides a valuable tool for SBR process optimization.