[Observations of predominant methanogens on biomass from AF, ABR, and UASB reactors treating different wastewaters].

The biomass taken from AF, ABR, and UASB digesters treating municipal wastewater, swine waste and molassese stillage wastewater, municipal and molassese stillage wastewater respectively, were observed by light, epifluorescence microscope and scanning electron microscope. The prevalent methanogens in these digesters were Methanothrix. Exception for ABR carried out to treat swine waste, Methanosarcina with three forms of aggregations, cysts, and granules were presented in other digesters. A suggestion can be made that reactors with packing materials, such as, anaerobic filters, anaerobic contact beds and two-phase methanation digesters can be used to accumulate Methanosarcina due to their morphological, mu max, and Ks characteristics, in order to increase the wastewater treatment efficiency further.