Realization of a Super High-rate Methane Recovery Technology from Waste and Wastewater.

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Whole cell in-situ hybridization with 16S rRNA targeted oligonucleotides was used to clarify the microbial ecological structure of sludge granules developed in laboratory- and pilot-scale upflow anaerobic sludge blanket (UASB) reactors receiving various types of wastewaters. Three different molecular probes : ARC915, complementary to conserve region of the 16S rRNA of the domain Archaea ; MT757, for genus Methanosaeta (Methanothrix), and MB1174, for Methanobacteriales, were employed in this study. The FISH results indicated that genera Archaea, Methanosaeta and Methanobacteriales accounted for approximately 30 to 60 %, 30 to 55%, and 10 to 30%, respectively of the DAPI (6 diamidino-2-phenylindole) stained cells (with responding to the total cell number) in the respective granular sludges.A strong correlation was observed between cell densities and methanogenic activities for both the Methanosaeta (acetate fed) and Methanobacteriales (hydrogen fed) genera. Topology of microbial structure of both the mesophilically- and thermophilically grown granules was investigated by dividing the individual whole granules into the outer-layer and the inner-layer portions. The methanogens were found more significant in the inner-layer portion. Similarly, thermophilic granules contained higher percentage of Methanobacter group that utilized hydrogen or formate for methanogenesis, as compared to the mesophilic. This suggests that syntrophic acetate oxidizing methanogenesis through hydrogen formation becomes more prominent under thermophilic conditions.