Modelling of hydrogenotrophic denitrification process in a venturi-integrated membrane bioreactor

Area of Science:

• Environmental Microbiology
• Biochemical Engineering
• Water Treatment Technologies

Background:

• Denitrification is crucial for removing nitrates from wastewater.
• Existing models often simplify microbial communities.
• Membrane bioreactors (MBRs) offer efficient wastewater treatment.

Purpose of the Study:

• To develop a model for hydrogenotrophic denitrification in a venturi-integrated submerged MBR.
• To differentiate between nitrate-reducing and nitrite-reducing biomass in the model.
• To identify kinetic and stoichiometric coefficients for the process.

Main Methods:

• Modeling a submerged membrane bioreactor (MBR) system.
• Operating the MBR in batch mode with varying nitrate concentrations (100-150 mg NO3-N/L).
• Subdividing biomass into nitrate-reducing and nitrite-reducing populations for simulation.

Main Results:

• The model achieved high accuracy (r² = 0.97-0.99) in simulating nitrate and nitrite-nitrogen concentrations.
• Nitrite-reducing biomass exhibited a higher maximum specific growth rate (0.06 h⁻¹) than nitrate-reducing biomass (0.0002 h⁻¹).
• Nitrite-reducing biomass also showed a higher growth yield coefficient (0.44 g/g) compared to nitrate-reducing biomass (0.31 g/g).

Conclusions:

• The developed model successfully simulates hydrogenotrophic denitrification in an MBR.
• Nitrite-reducing biomass plays a significant role and grows faster than nitrate-reducing biomass.
• The conversion of nitrite to nitrogen gas is the rate-limiting step in this denitrification process.