Strategies to Suppress Hydrogen-Consuming Microorganisms Affect Macro and Micro Scale Structure and Microbiology of Granular Sludge

• Autor(a) principal: Abreu, A. A.
• Data de Publicação: 2011
• Outros Autores: Alves, J. I., Pereira, M. A., Sousa, D. Z., Alves, M. M.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/1822/17604
• topic: biohydrogen; dark fermentation; image analysis; bacterial communities; EGSB reactors; Science & Technology

Treatment of anaerobic granules with heat and two chemical treatments, contacting with 2-bromoethanesulfonate (BES) and with BESþChloroform, were applied to suppress hydrogen-consuming microorganisms. Three mesophilic expanded granular sludge bed (EGSB) reactors— RHeat, RBES, and RBESþChlo—were inoculated with the treated sludges and fed with synthetic sugar-based wastewater (5 gCOD 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 RHeat was under 300mLH2 L 1 day 1, with a transient peak of 1,000 mLH2 L 1 day 1 after decreasing HRT. In RBESþChlo hydrogen production rate did not exceed 300mLH2 L 1 day 1 and there was granule fragmentation, release of free filaments from aggregates, and decrease of granule density. In RBES, there was an initial period with unstable hydrogen production, but a pulse of BES triggered its production rate to 700 200mLH2 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 H2-consuming microorganisms can cause changes in the macro- and microstructure of granular sludge, which can be incompatible with the operation of high-rate reactors.