title: Real time monitoring of a biogas digester with gas chromatography, near-infrared spectroscopy, and membrane-inlet mass spectrometry.
abstract: Four methods of monitoring the anaerobic digestion process were studied at pilot scale. The methods employed were Micro Gas Chromatography (μ-GC) and Membrane Inlet Mass Spectrometry (MIMS) for measurements in the gas phase, Near Infrared Spectroscopy (NIRS) and pH in the liquid phase. Micro Gas Chromatography accurately measured H(2), CH(4), H(2)S, N(2) and O(2) in the headspace whereas the MIMS accurately measured CH(4), CO(2), H(2)S, reduced organic sulfur compounds and p-cresol, also in the headspace. In the liquid phase, NIRS was found to be suitable for estimating the concentrations of acetate, propionate and total volatile fatty acids (VFA) but the error of prediction was too large for accurate quantification. Both the μ-GC and NIRS were low maintenance methods whereas the MIMS required frequent cleaning and background measurements.
authors.affiliation: Department of Biosystems Engineering, Faculty of Agricultural Sciences, Aarhus University, Blichers Allé 20, DK-8830 Tjele, Denmark.
authors.forename: Alastair James
authors.initials: AJ
authors.lastname: Ward
authors.forename: Emiliano
authors.initials: E
authors.lastname: Bruni
authors.forename: Morten K
authors.initials: MK
authors.lastname: Lykkegaard
authors.forename: Anders
authors.initials: A
authors.lastname: Feilberg
authors.forename: Anders P S
authors.initials: AP
authors.lastname: Adamsen
authors.forename: Anders P
authors.initials: AP
authors.lastname: Jensen
authors.forename: Allan K
authors.initials: AK
authors.lastname: Poulsen
mesh_terms: D000085:Acetates / Q000032:analysis; D001421:Bacteria, Anaerobic / Q000378:metabolism*; D056804:Biofuels; D002849:Chromatography, Gas / Q000379:methods*; D003408:Cresols / Q000032:analysis; D005232:Fatty Acids, Volatile / Q000032:analysis; D006859:Hydrogen / Q000032:analysis; D013058:Mass Spectrometry / Q000379:methods*; D008697:Methane / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis; D010100:Oxygen / Q000032:analysis; D010865:Pilot Projects; D011422:Propionates / Q000032:analysis; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D013457:Sulfur Compounds / Q000032:analysis*
chemical_list: D000085:Acetates; D056804:Biofuels; D003408:Cresols; D005232:Fatty Acids, Volatile; D011422:Propionates; D013457:Sulfur Compounds; C032538:4-cresol; D006859:Hydrogen; D009584:Nitrogen; D008697:Methane; D010100:Oxygen