MICROSTRUCTURAL ANALYSIS OF UASB GRANULES TREATING BREWERY WASTE-WATER

The microstructure of granules from a full-scale UASB reactor treating brewery wastewater was examined using light microscopy as well as the scanning and transmission electron microscopies. The granules typical ly have a complex, layered structure. The outer layer of the granule w as densely packed with various types of bacteria, including cocci, bac illi, Methanosarcina, and Methanothrix. The second layer was composed of a matrix of Methanothrix with two types of microcolony showing evid ence of syntrophic associations between hydrogen-producing acetogens a nd hydrogen-consuming methanogens. The interior of the granules, on th e other hand, was predominantly Methanothrix with scattered microcolon ies of syntrophic associations, which become sparse and disappeared to ward the centre core of the granule.