Multiple analysis reprogrammable titration analyser for the kinetic characterization of nitrifying and autotrophic denitrifying biomass

The system Multiple Analysis Reprogrammable TItratioN Analyser (MARTINA) based on titrimetric techniques has been used to kinetically characterize different types of sludges: nitrifying, enriched ammonia oxidizing and autotrophic denitrifying biomass. The titration system employed, combines the addition of NaOH solution and H2O2 solution in the mixed liquor to keep the pre-established value of pH and the dissolved oxygen concentration, respectively. Results obtained from repeated experiments performed with nitrifying sludge from municipal and industrial origin present slight differences (coefficient of variation lower than 30%) indicating that the method is highly reproducible. Besides, the kinetic parameters of the enriched ammonia oxidizing sludge obtained using the MARTINA system are comparable to those obtained using the respirometry indicating the reliability of this methodology. Changes in the procedure may be easily implemented in order to estimate half saturation constants with high values. On the other hand, experiments in anoxic conditions applied to the estimation of the kinetic parameters of the autotrophic denitrifying biomass have been successfully performed, even if this process involves a reaction characterized by slight pH changes. The titration system MARTINA is a reproducible, reliable, versatile and precise alternative to the traditional respirometric and substrate monitoring tests for the characterization of kinetics for a wide range of sludges in aerobic or anoxic conditions.