title: Microbial population dynamics in response to increasing loadings of pre-hydrolyzed pig manure in an expanded granular sludge bed.
abstract: In recent years, pig manure (PM) has been regarded as a valuable substrate for energy and resource recovery via bioprocesses such as anaerobic digestion (AD), however, the efficiency of digesting raw PM is limited by the presence of refractory compounds. In this study, we applied a series of pretreatment on raw PM, consisting of subsequent thermochemical pretreatment, enzymatic hydrolysis, tyndallization and filtration. The liquid PM hydrolysates were fed to an expanded granular sludge bed (EGSB) for the production of biogas. The general performance and population dynamics of the EGSB reactor were assessed during an extended operational period of 339 days. An efficient and stable digestion process was achieved under high organic loading rates (OLRs) up to 21 kg-COD/(m(3)·d), agreeing with a sludge loading rate of 0.75 kg-COD/(kg-VSS·d), 1600 mg-NH4(+)-N/L and 17 mg/L of free ammonia nitrogen. The tyndallization decreased the total amount of active cells from 1 × 10(8) to 1 × 10(2) CFU/ml. Hence, bio-augmentation with pigs' intestinal microbiota was absent and the community dynamics were mainly credited to the composition of the substrate (i.e. PM hydrolysates) and the environmental conditions inside the reactor. The results showed the influence of both the seed community and the imposed loading rates on the evolutionary trajectory of the EGSB microbial community. Four bacterial genera (Clostridium, Cytophaga, Bacillus and Bacteroides) and two methanogenic genera (Methanosaeta and Methanobacterium) dominated the communities. An obvious shift from aceticlastic Methanosaeta to hydrogenotrophic Methanobacterium appeared when the OLR was increased to over 10 kg-COD/(m(3)·d).
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 150090, Harbin, China; Section of Sanitary Engineering, Department of Water Management, Delft University of Technology, 2628, CN Delft, The Netherlands.
authors.forename: Haoyu
authors.initials: H
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 150090, Harbin, China; Section of Sanitary Engineering, Department of Water Management, Delft University of Technology, 2628, CN Delft, The Netherlands; Department of Chemical Engineering, Imperial College London, South Kensington Campus, SW7 2AZ, UK.
authors.forename: Yu
authors.initials: Y
authors.lastname: Tao
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 150090, Harbin, China.
authors.forename: Dawen
authors.initials: D
authors.lastname: Gao
authors.affiliation: Section of Sanitary Engineering, Department of Water Management, Delft University of Technology, 2628, CN Delft, The Netherlands.
authors.forename: Gang
authors.initials: G
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 150090, Harbin, China.
authors.forename: Chunhong
authors.initials: C
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 150090, Harbin, China. Electronic address: rnq@hit.edu.cn.
authors.forename: Nanqi
authors.initials: N
authors.lastname: Ren
authors.affiliation: Section of Sanitary Engineering, Department of Water Management, Delft University of Technology, 2628, CN Delft, The Netherlands.
authors.forename: Jules B
authors.initials: JB
authors.lastname: van Lier
authors.affiliation: Section of Sanitary Engineering, Department of Water Management, Delft University of Technology, 2628, CN Delft, The Netherlands.
authors.forename: Merle
authors.initials: M
authors.lastname: de Kreuk
mesh_terms: D000693:Anaerobiosis; D000818:Animals; D001419:Bacteria / Q000235:genetics; D056804:Biofuels; D019149:Bioreactors / Q000382:microbiology*; D005374:Filtration; D006358:Hot Temperature; D006868:Hydrolysis; D008372:Manure / Q000382:microbiology*; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology*; D034421:Sus scrofa; D014865:Waste Disposal, Fluid / Q000379:methods
chemical_list: D056804:Biofuels; D008372:Manure; D012722:Sewage
keywords: Ammonia; Anaerobic digestion; Microbial community; OTU network; Organic loading rate; Pig manure