Autohydrogenotrophic perchlorate reduction kinetics of a microbial consortium in the presence and absence of nitrate

This is the first study to model the effects of nitrate on autohydrogenotrophic perchlorate biokinetics. Batch experiments demonstrated that the presence of nitrate significantly inhibited perchlorate degradation by a hydrogen-oxidizing, perchlorate-reducing microbial consortium. However, the consortium was capable of significant perchlorate reduction while the bulk of the nitrate was still present. Results showed that a modified competitive inhibition model successfully predicted autohydrogenotrophic perchlorate degradation in the presence of nitrate (initial concentrations of ∼230 μg ClO4−/L and 2.2–4.6 mg NO3−-N/L). The model describes perchlorate degradation as a function of the biomass, perchlorate, hydrogen, and nitrate concentrations, as well as the single-component perchlorate (28 μg/L), hydrogen (2.3 × 10−6 M (aq)), and nitrate (0.15 mg/L as N) half-saturation coefficients (Ks) and perchlorate maximum substrate utilization rate (k  ) (1.8 μg ClO4−/mg TSS-hr). Single-component parameters were obtained through a series of batch experiments performed under perchlorate-, nitrate-, and hydrogen-limiting conditions with initial concentrations of 80–340 μg ClO4−/L, 2.7–3.6 mg NO3−-N/L, and 1%–3% H2 (g) by volume.

► Effects of nitrate on autohydrogenotrophic perchlorate biokinetics were modeled.
► A modified competitive inhibition model was used.
► The model effectively predicted perchlorate degradation in the presence of nitrate.