Estimation of (C/N) ratio for microbial denitrification

Area of Science:

• Environmental microbiology
• Biochemical engineering

Background:

• Elemental balances are crucial for understanding microbial growth.
• Denitrification processes require precise nutrient ratios for efficiency.

Purpose of the Study:

• To apply elemental balances for calculating the carbon-to-nitrogen (C/N) ratio in denitrification.
• To estimate the critical C/N ratio using the correlation between biomass yield and substrate reduction degree.

Main Methods:

• Utilized elemental balances of microbial growth.
• Correlated biomass yield coefficient with the degree of substrate reduction.
• Conducted batch cultures with denitrifying bacteria (Ervinia sp.) using glucose, sodium acetate, and methanol.

Main Results:

• Established a method to calculate the C/N ratio in denitrification.
• Determined a critical (COD/N) ratio of 7.6 g O2 g(-1) N for substrates with a degree of reduction below 4.67.
• Experimental results using Ervinia sp. generally supported the theoretical calculations.

Conclusions:

• Elemental balances provide a reliable method for determining C/N ratios in denitrification.
• The critical (COD/N) ratio is constant for low-degree-of-reduction substrates.
• Theoretical models for denitrification are validated by experimental data.