Related Experiment Videos
Optimizing experimental design to estimate ammonia and nitrite oxidation biokinetic parameters from batch
Kartik Chandran1, Barth F Smets
1Earth and Environmental Engineering, Columbia University, New York, NY 10027, USA. kc2288@columbia.edu
Water Research
|November 23, 2005
Summary
A new respirometric assay improves nitrification modeling by optimizing substrate additions. This method enhances kinetic parameter estimation for both ammonium-nitrogen (NH4+-N) and nitrite-nitrogen (NO2--N) oxidation steps, even when rates are similar.
Area of Science:
- Environmental microbiology
- Biogeochemical cycles
- Wastewater treatment
Background:
- Accurate nitrification modeling requires understanding the distinct oxidation dynamics of ammonium-nitrogen (NH4+-N) to nitrite-nitrogen (NO2--N) and NO2--N to nitrate-nitrogen (NO3--N).
- Previous work demonstrated that two-step nitrification models can estimate kinetic parameters from respirograms, but only if the data sufficiently captures both oxidation steps.
Purpose of the Study:
- To develop an improved batch nitrification respirometric assay that maximizes kinetic information content for both nitrification steps.
- To enable accurate estimation of Monod kinetic parameters for both NH4+-N to NO2--N and NO2--N to NO3--N oxidation.
Main Methods:
- Implemented a novel assay involving an initial NH4+-N pulse followed by a second, optimally timed NO2--N pulse to nitrifying biomass.
- Determined the optimal time for the NO2--N pulse by maximizing the determinant of the Fisher information matrix (Det(F)) or by observing NH4+-N depletion.
Main Results:
- The developed assay effectively generates respirograms rich in kinetic information for both nitrification steps.
- Accurate Monod kinetic parameter estimates were achieved even when the pseudo-first order rate coefficients for the two steps were nearly equal.
Conclusions:
- This optimized respirometric assay provides a robust method for characterizing nitrification kinetics.
- The assay is particularly valuable for conditions where standard NH4+-N to NO3--N oxidation respirograms lack sufficient information on NO2--N oxidation.