Microbial diversity in UASB reactors

Upflow anaerobic sludge blanket (UASB) process is now widely used for the treatment of industrial wastes. Immobilized methanogenic granules play a vital role in such a process. In this study, microbial diversity of these granules from five different full-scale and laboratory UASB reactors operating under different conditions was investigated. The results were categorized on the basis of four different cases of operational and environmental conditions. Predominant methanogens in granules operating under a specific set of operational or environmental conditions were generally different from each other. The results indicated that microorganisms resembling those of the genera Methanobacterium, Methanobrevibacter, Methanothrix and Methanosarcina dominated the granules. However, a variety of other species co-existed with the dominant methanogens. The presence of diverse bacterial groups manifested a unique property of the granules of seeding and fast start-up of other UASB reactors.