Biological treatment of selenium-laden wastewater containing nitrate and sulfate in an upflow anaerobic sludge bed reactor at pH 5.0

Lea Chua Tan, Yarlagadda V. Nancharaiah, Shipeng Lu, Eric D. van Hullebusch, Robin Gerlach, Piet N.L. Lens

    Research output: Contribution to journalArticleScientificpeer-review

    34 Citations (Scopus)


    This study investigated the removal of selenate (SeO4 2−), sulfate (SO4 2−) and nitrate (NO3 ) at different influent pH values ranging from 7.0 to 5.0 and 20 °C in an upflow anaerobic sludge blanket (UASB) reactor using lactate as an electron donor. At pH 5.0, the UASB reactor showed a 20–30% decrease in reactor performance compared to operation at pH 5.5 to 7.0, reaching removal efficiencies of 79%, 15%, 43% and 61% for NO3 , SO4 2−, Setotal and Sediss, respectively. However, the reactor stability was an issue upon lowering the pH to 5.0 and further experiments are recommended. The sludge formed during low pH operation had a fluffy, floc-like appearance with filamentous structure, possibly due to the low polysaccharide (PS) to protein (PN) ratio (0.01 PS/PN) in the soluble extracellular polymeric substances (EPS) matrix of the biomass. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) analysis of the sludge confirmed Se oxyanion reduction and deposition of Se0 particles inside the biomass. Microbial community analysis using Illumina MiSeq sequencing revealed that the families of Campylobacteraceae and Desulfomicrobiaceae were the dominant phylotypes throughout the reactor operation at approximately 23% and 10% relative abundance, respectively. Furthermore, approximately 10% relative abundance of both Geobacteraceae and Spirochaetaceae was observed in the granular sludge during the pH 5.0 operation. Overall, this study demonstrated the feasibility of UASB operation at pH values ranging from 7.0 to 5.0 for removing Se and other oxyanions from wastewaters.

    Original languageEnglish
    Pages (from-to)684-693
    Number of pages10
    Publication statusPublished - 1 Nov 2018
    Publication typeA1 Journal article-refereed


    • Acid mine drainage
    • Anaerobic granular sludge
    • Microbial diversity
    • Selenate bioreduction
    • UASB reactor

    Publication forum classification

    • Publication forum level 1

    ASJC Scopus subject areas

    • Environmental Engineering
    • Environmental Chemistry
    • General Chemistry
    • Pollution
    • Health, Toxicology and Mutagenesis


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