| The process of anaerobic granule formation was characterized in three laboratory-scale upflow anaerobic sludge blanket (UASB) reactors (35{dollar}spcirc{dollar}C) fed glucose molasses solution or brewery wastewater, using both digested sewage sludge and aerobic activated sludge as inocula. The granulation process in this study was basically the same as that reported using volatile fatty acid (VFA) mixtures. An important parameter affecting the granulation process was specific COD loading rate.; Two types of granules developed on VFA mixtures containing low sulfate concentrations ({dollar}<{dollar}0.15 mM) were compared systematically as to their microbial population, operational performance, granular structure, and kinetic parameters. The R-granules which had rod-type Methanothrix species as predominant acetate-utilizing methanogens showed higher granule density and better operational performance than the F-granules which contained filamentous Methanothrix species as predominant species.; Granules from an industrial UASB reactor treating brewery wastewater containing a moderate sulfate concentration (0.6 to 1.3 mM) were characterized in terms of the role of sulfate reducing bacteria (SRB) in substrate metabolism and granule structure. Syntrophic propionate and ethanol degradation was performed by SRB.; Five methanogenic strains, two propionate-degrading strains, and two butyrate-degrading strains were isolated from the R-granules and identified as prevalent organisms. VFA degradation was characterized by comparing these isolated species versus the granules in terms of the role of different species in VFA metabolism, including the synthesis of valerate and 2-methylbutyrate, isomerization between isobutyrate and butyrate, synthesis of formate from H{dollar}sb2{dollar} plus HCO{dollar}sb3sp-{dollar}, and interspecies electron transfer.; Methanobacterium formicicum T1N was a predominant species in the R-granules and played an important role in granule formation and it formed aggregates in an UASB reactor (35{dollar}spcirc{dollar}C) fed with formate as substrate. The aggregate formation by the isolated methanogenic and VFA-degrading cultures from the R-granules was investigated. Defined granules were formed in a laboratory-UASB reactor (35{dollar}spcirc{dollar}C) fed with a medium containing acetate, propionate and butyrate mixture using these species as inoculum: Methanobacterium formicicum T1N, Methanothrix M7, Methanosarcina mazei T18, propionate degrading strain PT and butyrate degrading strain BH. Methanobacterium formicicum and Methanothrix species were demonstrated to be adhesive organisms important for granule formation. |
