title: Strategies to suppress hydrogen-consuming microorganisms affect macro and micro scale structure and microbiology of granular sludge.
abstract: Treatment of anaerobic granules with heat and two chemical treatments, contacting with 2-bromoethanesulfonate (BES) and with BES + Chloroform, were applied to suppress hydrogen-consuming microorganisms. Three mesophilic expanded granular sludge bed (EGSB) reactors-R(Heat), R(BES), and R(BES + Chlo)--were inoculated with the treated sludges and fed with synthetic sugar-based wastewater (5 g(COD) L(-1), HRT 20-12 h). Morphological integrity of granules and bacterial communities were assessed by quantitative image analysis and 16S rRNA gene based techniques, respectively. Hydrogen production in R(Heat) was under 300 mL H(2) L(-1) day(-1), with a transient peak of 1,000 mL H(2) L(-1) day(-1) after decreasing HRT. In R(BES + Chlo) hydrogen production rate did not exceed 300 mL H(2) L(-1) day(-1) and there was granule fragmentation, release of free filaments from aggregates, and decrease of granule density. In R(BES), there was an initial period with unstable hydrogen production, but a pulse of BES triggered its production rate to 700 ± 200 mL H(2) L(-1) day(-1). This strategy did not affect granules structure significantly. Bacteria branching within Clostridiaceae and Ruminococcaceae were present in this sludge. This work demonstrates that, methods applied to suppress H(2)-consuming microorganisms can cause changes in the macro- and microstructure of granular sludge, which can be incompatible with the operation of high-rate reactors.
authors: IBB-Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal. angela_abreu@deb.uminho.pt
authors: A A
authors: AA
authors: Abreu
authors: J I
authors: JI
authors: Alves
authors: M A
authors: MA
authors: Pereira
authors: D Z
authors: DZ
authors: Sousa
authors: M M
authors: MM
authors: Alves
mesh_terms: D017738:Alkanesulfonic Acids / Q000633:toxicity; D000693:Anaerobiosis; D000900:Anti-Bacterial Agents / Q000633:toxicity; D044822:Biodiversity; D002725:Chloroform / Q000633:toxicity; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D006094:Gram-Positive Bacteria / Q000145:classification* / Q000254:growth & development / Q000378:metabolism*; D006859:Hydrogen / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012722:Sewage / Q000382:microbiology*; D018508:Water Purification
chemical_list: D017738:Alkanesulfonic Acids; D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D012722:Sewage; C018853:2-bromoethanesulfonic acid; D002725:Chloroform; D006859:Hydrogen