title: Mathematical models and bacterial communities for ammonia toxicity in mesophilic anaerobes not acclimated to high concentrations of ammonia.
abstract: In this study, we evaluated ammonia toxicity in mesophilic anaerobic digestion at various pH values and total ammonia nitrogen (TAN) concentrations. We performed anaerobic toxicity assays (ATAs) to evaluate the toxicity effects of TAN and pH on mesophilic anaerobic digestion. Modeling based on the results of the ATAs indicated that the specific methanogenic activity (SMA) decreased by 30% at a TAN concentration higher than 3.0 g/L compared to a TAN concentration of 0 g/L. In addition, the highest SMA for a given TAN level (0.5-10.0 g/L) was observed at a pH of around 7.6. The results of bacterial community analyses showed that the diversity and richness of microorganisms with increasing TAN concentration were decreased. Chloroflexi and Synergistetes were the dominant phyla at TAN concentrations less than 3.0 g/L, and Firmicutes was the dominant phylum at TAN concentrations higher than 3.0 g/L, implying that the ammonia toxicity concentration may influence the kind of dominant species. In conclusion, to start a stable mesophilic anaerobic digestion concerning ammonia toxicity, a TAN concentration less than 3.0 g/L is preferable.
authors.affiliation: Plant Engineering Center, Institute for Advanced Engineering, 51 Goan-ro, Yongin City, Kyeonggido 175-28, Republic of Korea; Department of Civil & Environmental Engineering, Hanyang University, 55 Hanyangdaehak-ro, Ansan City, Kyeonggido 155-88, Republic of Korea E-mail: moonilkim@hanyang.co.kr.
authors.forename: Seyong
authors.initials: S
authors.lastname: Park
authors.affiliation: Department of Civil & Environmental Engineering, Hanyang University, 55 Hanyangdaehak-ro, Ansan City, Kyeonggido 155-88, Republic of Korea E-mail: moonilkim@hanyang.co.kr.
authors.forename: Fenghao
authors.initials: F
authors.lastname: Cui
authors.affiliation: Department of Civil & Environmental Engineering, Hanyang University, 55 Hanyangdaehak-ro, Ansan City, Kyeonggido 155-88, Republic of Korea E-mail: moonilkim@hanyang.co.kr.
authors.forename: Kyung
authors.initials: K
authors.lastname: Mo
authors.affiliation: Department of Civil & Environmental Engineering, Hanyang University, 55 Hanyangdaehak-ro, Ansan City, Kyeonggido 155-88, Republic of Korea E-mail: moonilkim@hanyang.co.kr.
authors.forename: Moonil
authors.initials: M
authors.lastname: Kim
mesh_terms: D000064:Acclimatization; D000641:Ammonia / Q000737:chemistry / Q000633:toxicity*; D000693:Anaerobiosis; D001421:Bacteria, Anaerobic / Q000187:drug effects*; D019149:Bioreactors / Q000382:microbiology*; D006863:Hydrogen-Ion Concentration; D008954:Models, Biological
chemical_list: D000641:Ammonia