Microbial characterization and removal of anionic surfactant in an expanded granular sludge bed reactor

This study evaluated linear alkylbenzene sulfonate removal in an expanded granular sludge bed reactor with hydraulic retention times of 26 h and 32 h. Sludge bed and separator phase biomass were phylogenetically characterized (sequencing 16S rRNA) and quantified (most probable number) to determine the total anaerobic bacteria and methanogenic Archaea. The reactor was fed with a mineral medium supplemented with 14 mg l(-1) LAS, ethanol and methanol. The stage I-32 h consisted of biomass adaptation (without LAS influent) until reactor stability was achieved (COD removal >97%). In stage II-32 h, LAS removal was 74% due to factors such as dilution, degradation and adsorption. Higher HRT values increased the LAS removal (stage III: 26 h - 48% and stage IV: 32 h - 64%), probably due to increased contact time between the biomass and LAS. The clone libraries were different between samples from the sludge bed (Synergitetes and Proteobacteria) and the separator phase (Firmicutes and Proteobacteria) biomass. (C) 2011 Elsevier Ltd. All rights reserved.

Performance and composition of bacterial communities in anaerobic fluidized bed reactors for hydrogen production: Effects of organic loading rate and alkalinity

This study evaluated the effects of the organic loading rate (OLR) and pH buffer addition on hydrogen production in two anaerobic fluidized bed reactors (AFBRs) operated simultaneously. The AFBRs were fed with glucose, and expanded clay was used as support material. The reactors were operated at a temperature of 30 degrees C, without the addition of a buffer (AFBR1) and with the addition of a pH buffer (AFBR2, sodium bicarbonate) for OLRs ranging from 19.0 to 140.6 kg COD m(-3) d(-1) (COD: chemical oxygen demand). The maximum hydrogen yields for AFBR1 and AFBR2 were 2.45 and 1.90 mol H-2 mol(-1) glucose (OLR of 84.3 kg COD m(-3) d(-1)), respectively. The highest hydrogen production rates were 0.95 and 0.76 L h(-1) L-1 for AFBR1 and AFBR2 (OLR of 140.6 kg COD m(-3) d(-1)), respectively. The operating conditions in AFBR1 favored the presence of such bacteria as Clostridium, while the bacteria in AFBR2 included Clostridium, Enterobacter, Klebsiella, Veillonellaceae, Chryseobacterium, Sporolactobacillus, and Burkholderiaceae. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.