Abstract
A mesophilic non-dilution methane fermentation reactor for wet-biomass was operated continuously using dosed shredded paper, reducing nitrogen components to avoid inhibition of the reactor caused by ammonia accumulation. Simultaneous investigation was conducted using the 16S rRNA gene clone library and quantitative PCR (Real-Time PCR). When wet biomass alone was fed to the reactor, ammonia accumulated and the reactor performance deteriorated. A closely related clone showed predominance of 45% in Finegoldia magna, which were the ammonia-producing bacteria. Shredded paper was added to the reactor to decrease the ammonium concentration, thereby inhibiting the clone. However, results show that the density of Archaeal cells in the reactor was decreased (two orders) by their addition. Consequently, propionic acid accumulated in the reactor. Even a batch test using sludge in the methane fermentation reactor and shredded paper produced a similar result. Clonal bacteria belonging to the phylum Firmicutes in domain Bacteria and hydrogenotrophic methanogen (genus Methanobacterium, genus Methanoculleus) in the domain Archaea were implicated as the dominant Bacteria in the reactor.
