Exploring the performance limits of a sulfidogenic UASB during the long-term use of crude glycerol as electron donor

E. Fernández-Palacios, J. Lafuente, M. Mora, D. Gabriel*

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

4 Citations (Scopus)

Abstract

© 2019 Elsevier B.V. SOx contained in flue gases and S-rich liquid effluents can be valorized to recover elemental sulfur in a two-stage bioscrubbing process. The reduction of sulfate to sulfide is the most crucial stage to be optimized. In this study, the long-term performance of an up-flow anaerobic sludge blanket (UASB) reactor using crude glycerol as electron donor was assessed. The UASB was operated for 400 days with different sulfate and organic loading rates (SLR and OLR, respectively) and a COD/S-SO42− ratio ranging from 3.8 g O2 g−1 S to 5.4 g O2 g−1 S. After inoculation with methanogenic, granular biomass, the competition between sulfate-reducing and methanogenic microorganisms determined to what extent dissolved sulfide and methane were produced. After the complete washout of methanogens, which was revealed by next-generation sequencing analysis, the highest S-EC was reached in the system. The highest average sulfate elimination capacity (S-EC = 4.3 kg S m−3d−1) was obtained at a COD/S-SO42− ratio of 5.4 g O2 g−1 S and an OLR of 24.4 kg O2 m−3d−1 with a sulfate removal efficiency of 94%. The conversion of influent COD to methane decreased from 12% to 2.5% as the SLR increased while a large fraction of acetate (35% of the initial COD) was accumulated. Our data indicate that crude glycerol can promote sulfidogenesis. However, the disappearance of methanogens in the long-term due to the out competition by sulfate reducing bacteria, lead to such large accumulation of acetate.
Original languageEnglish
Pages (from-to)1184-1192
Number of pages9
JournalScience of the Total Environment
Volume688
DOIs
Publication statusPublished - 20 Oct 2019

Keywords

  • Bioscrubber
  • Carbon sink
  • Crude glycerol
  • SO valorization
  • SRB
  • UASB
  • SCALE ANAEROBIC BIOREACTOR
  • FATTY-ACID DEGRADATION
  • FRESH-WATER SEWAGE
  • FLUE-GAS DESULFURIZATION
  • CO-DIGESTION
  • INFLUENT COD/SO42-RATIOS
  • REDUCTION
  • WASTE-WATER
  • SLUDGE
  • SO2 valorization
  • SULFATE-REDUCING BACTERIA

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