title: Influence of digestion temperature and organic loading rate on the continuous anaerobic treatment of process liquor from hydrothermal carbonization of sewage sludge.
abstract: This experimental study investigates the use of process liquor from hydrothermal carbonization (HTC) of sewage sludge as sole substrate for anaerobic digestion (AD). The process performance at 37°C (mesophilic) and 55°C (thermophilic) was determined based on two identical continuously-fed anaerobic filters (26 L each) operated for 20 weeks. During operation, the organic loading rate was stepwise increased from 1 to 5 gCOD L(-1)d(-)(1). This decreased the hydraulic retention time from 34 to 5 days. Significant differences in methane production were not observed as both reactors yielded up to 0.18 LCH4 gCOD(-)(1). Increased temperature had no effect on the steady-state COD removal efficiency with both reactors stabilized at 68-75%. Macro- and micronutrients were provided by HTC liquor in sufficient concentrations throughout the experiment. Methanogenesis was identified as the speed-limiting step in anaerobic digestion of HTC liquor. Hydrolysis was of an order of magnitude faster than methanogenesis.
authors.affiliation: Leibniz Institute for Agricultural Engineering Potsdam-Bornim, Max-Eyth-Allee 100, 14469 Potsdam, Germany; Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany. Electronic address: bwirth@atb-potsdam.de.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Wirth
authors.affiliation: Leibniz Institute for Agricultural Engineering Potsdam-Bornim, Max-Eyth-Allee 100, 14469 Potsdam, Germany; Department of Chemical and Materials Engineering, University of Nevada Reno, 1664 N. Virginia Street, Reno, NV 89557, USA.
authors.forename: Toufiq
authors.initials: T
authors.lastname: Reza
authors.affiliation: Leibniz Institute for Agricultural Engineering Potsdam-Bornim, Max-Eyth-Allee 100, 14469 Potsdam, Germany; UK Biochar Research Centre, School of GeoSciences, University of Edinburgh, Crew Building, King's Building, Edinburgh EH9 3JN, United Kingdom.
authors.forename: Jan
authors.initials: J
authors.lastname: Mumme
mesh_terms: D000693:Anaerobiosis / Q000502:physiology*; D002244:Carbon / Q000378:metabolism; D006868:Hydrolysis; D012722:Sewage; D013696:Temperature
chemical_list: D012722:Sewage; D002244:Carbon
keywords: Anaerobic digestion; Hydrothermal carbonization; Mesophilic; Sewage sludge; Thermophilic