title: Biochar alleviates combined stress of ammonium and acids by firstly enriching Methanosaeta and then Methanosarcina.
abstract: This investigation evaluated the effectiveness of biochar of different particle sizes in alleviating ammonium (NH4(+)) inhibition (up to 7 g-N/L) during anaerobic digestion of 6 g/L glucose. Compared to the control treatment without biochar addition, treatments that included biochar particles 2-5 mm, 0.5-1 mm and 75-150 μm in size reduced the methanization lag phase by 23.9%, 23.8% and 5.9%, respectively, and increased the maximum methane production rate by 47.1%, 23.5% and 44.1%, respectively. These results confirmed that biochar accelerated the initiation of methanization during anaerobic digestion under double inhibition risk from both ammonium and acids. Furthermore, fine biochar significantly promoted the production of volatile fatty acids (VFAs). Comparative analysis on the archaeal and bacterial diversity at the early and later stages of digestion, and in the suspended, biochar loosely bound, and biochar tightly bound fractions suggested that, in suspended fractions, hydrogenotrophic Methanobacterium was actively resistant to ammonium. However, acetoclastic Methanosaeta can survive at VFAs concentrations up to 60-80 mmol-C/L by improved affinity to conductive biochar, resulting in the accelerated initiation of acetate degradation. Improved methanogenesis was followed by the colonization of the biochar tightly bound fractions by Methanosarcina. The selection of appropriate biochar particles sizes was important in facilitating the initial colonization of microbial cells.
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Tongji University, Shanghai 200092, China; Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092, China.
authors.forename: Fan
authors.initials: F
authors.lastname: Lü
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Tongji University, Shanghai 200092, China.
authors.forename: Chenghao
authors.initials: C
authors.lastname: Luo
authors.affiliation: Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092, China; Centre for the Technology Research and Training on Household Waste in Small Towns & Rural Area, Ministry of Housing and Urban-Rural Development (MOHURD) of China, China.
authors.forename: Liming
authors.initials: L
authors.lastname: Shao
authors.affiliation: Institute of Waste Treatment and Reclamation, Tongji University, Shanghai 200092, China; Centre for the Technology Research and Training on Household Waste in Small Towns & Rural Area, Ministry of Housing and Urban-Rural Development (MOHURD) of China, China. Electronic address: solidwaste@tongji.edu.cn.
authors.forename: Pinjing
authors.initials: P
authors.lastname: He
mesh_terms: D000143:Acids / Q000378:metabolism; D064751:Ammonium Compounds / Q000737:chemistry*; D000693:Anaerobiosis; D001419:Bacteria / Q000254:growth & development / Q000378:metabolism; D002606:Charcoal / Q000737:chemistry*; D005232:Fatty Acids, Volatile / Q000378:metabolism; D008697:Methane / Q000378:metabolism; D017014:Methanobacterium / Q000254:growth & development / Q000378:metabolism; D017020:Methanosarcina / Q000254:growth & development / Q000378:metabolism; D019640:Methanosarcinales / Q000254:growth & development / Q000378:metabolism*; D010316:Particle Size; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D000143:Acids; D064751:Ammonium Compounds; D005232:Fatty Acids, Volatile; C540010:biochar; D002606:Charcoal; D008697:Methane
keywords: Ammonium toxicity; Anaerobic digestion; Interspecies electron transfer; Methanosarcinales; Syntrophic acetate oxidation; Waste treatment