title: Ammonia-methane two-stage anaerobic digestion of dehydrated waste-activated sludge.
abstract: The study investigated methane production from dehydrated waste-activated sludge (DWAS) with approximately 80% water content under thermophilic conditions. The repeated batch-wise treatment of DWAS using methanogenic sludge unacclimated to high concentrations of ammonia, increased the ammonia production up to 7,600 mg N per kilogram total wet sludge of total ammonia concentration, and stopped the methane production. Investigation revealed that the loading ratio of DWAS for methanogenic sludge influences anaerobic digestion. Methane production significantly decreased and ammonia concentration increased with the increase in loading ratio of DWAS. Since the semicontinuous culture revealed that approximately 50% of organic nitrogen in DWAS converted to ammonia at sludge retention time (SRT) after 4 days at 37 degrees C and 1.33 days at 55 degrees C, the previous stripping of the ammonia produced from DWAS was carried out. The stripping of ammonia increased methane production significantly. This ammonia-methane two-stage anaerobic digestion demonstrated a successful methane production at SRT 20 days in the semicontinuous operation using a laboratory-scale reactor system.
authors.affiliation: Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1, Kagamiyama, Higashi-Hiroshima 739-8530, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Nakashimada
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Ohshima
authors.forename: Hisao
authors.initials: H
authors.lastname: Minami
authors.forename: Hironori
authors.initials: H
authors.lastname: Yabu
authors.forename: Yuzaburo
authors.initials: Y
authors.lastname: Namba
authors.forename: Naomichi
authors.initials: N
authors.lastname: Nishio
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D018533:Biomass; D019149:Bioreactors; D003681:Dehydration; D005285:Fermentation; D007700:Kinetics; D008697:Methane / Q000378:metabolism*; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology
chemical_list: D012722:Sewage; D000641:Ammonia; D008697:Methane