Browsing by Author "Lu, Shipeng"

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Biological treatment of selenium-laden wastewater containing nitrate and sulfate in an upflow anaerobic sludge bed reactor at pH 5.0
(2018-11) Tan, Lea Chua; Nancharaiah, Yarlagadda V.; Lu, Shipeng; van Hullebusch, Eric D.; Gerlach, Robin; Lens, Piet N. L.
This study investigated the removal of selenate (SeO42−), sulfate (SO42−) 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−, SO42−, 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.
Schwertmannite formation at cell junctions by a new filament-forming Fe(II)-oxidizing isolate affiliated with the novel genus
(2016-01) Mori, Jiro F.; Lu, Shipeng; H�ndel, Matthias; Totsche, Kai Uwe; Neu, Thomas R.; Vlad Iancu, Vasile; Tarcea, Nicolae; Popp, J�rgen; K�sel, Kirsten
A new acidophilic iron-oxidizing strain (C25) belonging to the novel genus Acidithrix was isolated from pelagic iron-rich aggregates (‘iron snow’) collected below the redoxcline of an acidic lignite mine lake. Strain C25 catalysed the oxidation of ferrous iron [Fe(II)] under oxic conditions at 25 8C at a rate of 3.8 mM Fe(II) day21 in synthetic medium and 3.0 mM Fe(II) day21 in sterilized lake water in the presence of yeast extract, producing the rust-coloured, poorly crystalline mineral schwertmannite [Fe(III) oxyhydroxylsulfate]. During growth, rod-shaped cells of strain C25 formed long ﬁlaments, and then aggregated and degraded into shorter fragments, building large cell–mineral aggregates in the late stationary phase. Scanning electron microscopy analysis of cells during the early growth phase revealed that Fe(III)-minerals were formed as single needles on the cell surface, whereas the typical pincushion-like schwertmannite was observed during later growth phases at junctions between the cells, leaving major parts of the cell not encrusted. This directed mechanism of biomineralization at speciﬁc locations on the cell surface has not been reported from other acidophilic iron-oxidizing bacteria. Strain C25 was also capable of reducing Fe(III) under micro-oxic conditions which led to a dissolution of the Fe(III)-minerals. Thus, strain C25 appeared to have ecological relevance both for the formation and transformation of the pelagic iron-rich aggregates at oxic/anoxic transition zones in the acidic lignite mine lake.