wAbstract
@Anaerobic batch and flow-through experiments were performed to
confirm the role of pyrite as electron donor in bacterial denitrification
and to look into the feasibility of pyrite-driven denitrification
of nitrate-contaminated groundwater. Nitrate reduction was satisfactorily
accomplished in experiments with pyrite as the sole electron donor,
in presence of the autotrophic denitrifying bacterium Thiobacillus
denitrificans and at nitrate concentrations comparable to
those observed in contaminated groundwater. The experimental results
corroborated field studies in which the reaction occurred in aquifers.
Nitrate reduction rates and nitrate removal efficiencies were
dependent on pyrite grain size, initial nitrate concentration,
nitrate-loading rate and pH. The N and O isotopic enrichment factors
(ΓN and ΓO) obtained experimentally for pyrite-driven nitrate
reduction by T. denitrificans ranged from -13.5ρ to -15.0ρ
and from -19.0ρ to -22.9ρ, respectively. These values indicated
the magnitude of the isotope fractionation that occurs in nitrate-contaminated
aquifers dominated by autotrophic denitrification.
Keywords: Denitrification; Pyrite; Dissolution; Thiobacillus
denitrificans; Isotope fractionationx
1. Introduction
2. Materials and methods
@2.1. Pyrite characterization and preparation
@2.2. Culture preparation
@2.3. Experimental set-up
@2.4. Analytical methods
3. Results and discussion
@3.1. Nitrate reduction
@3.2. Stoichiometry of the pyrite-driven denitrification process
@3.3. Nitrate reduction rates
@3.4. N and O isotope fractionation
4. Conclusions
Acknowledgments
References