Coupling respirometry and titrimetry for the characterization of the biological activity of a SO-NR consortium

Determining growth rates and kinetic mechanisms of microbial consortia often needs of combining several tests and techniques. The present work demonstrates that combining titrimetric and respirometric data obtained in a single batch test allows obtaining the stoichiometric coefficients, biomass-substrate yields and biological oxidation rates for sulfide-oxidizing nitrate-reducing consortia obtained from an anoxic biotrickling filter for biogas desulfurization. Thiosulfate oxidation using either nitrate or nitrite was quantified as well as the biological production of proton linked to the process to solve the stoichiometry of the two-step autotrophic denitrification associated to thiosulfate oxidation. To obtain accurate titrimetric data related to the biological activity, carbon dioxide stripping was modeled to improve the sensitivity of titrimetric measurements and also to ensure no carbon source limitation during respirometric tests.