AUTHOR=Carboni M. F. , Florentino A. P. , Costa R. B. , Zhan X. , Lens P. N. L. 

TITLE=Enrichment of Autotrophic Denitrifiers From Anaerobic Sludge Using Sulfurous Electron Donors

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.678323

DOI=10.3389/fmicb.2021.678323

ISSN=1664-302X

ABSTRACT=<p>This study compared the rates and microbial community development in batch bioassays on autotrophic denitrification using elemental sulfur (S<sup>0</sup>), pyrite (FeS<sub>2</sub>), thiosulfate (S<sub>2</sub>O<sub>3</sub><sup>2–</sup>), and sulfide (S<sup>2–</sup>) as electron donor. The performance of two inocula was compared: digested sludge (DS) from a wastewater treatment plant of a dairy industry and anaerobic granular sludge (GS) from a UASB reactor treating dairy wastewater. All electron donors supported the development of a microbial community with predominance of autotrophic denitrifiers during the enrichments, except for sulfide. For the first time, pyrite revealed to be a suitable substrate for the growth of autotrophic denitrifiers developing a microbial community with predominance of the genera <italic>Thiobacillus</italic>, <italic>Thioprofundum</italic>, and <italic>Ignavibacterium</italic>. Thiosulfate gave the highest denitrification rates removing 10.94 mM NO<sub>3</sub><sup>–</sup> day<sup>–1</sup> and 8.98 mM NO<sub>3</sub><sup>–</sup> day<sup>–1</sup> by DS and GS, respectively. This was 1.5 and 6 times faster than elemental sulfur and pyrite, respectively. Despite the highest denitrification rates observed in thiosulfate-fed enrichments, an evaluation of the most relevant parameters for a technological application revealed elemental sulfur as the best electron donor for autotrophic denitrification with a total cost of 0.38 € per m<sup>3</sup> of wastewater treated.</p>