title: Pyrolysis of hydrochar from digestate: Effect of hydrothermal carbonization and pyrolysis temperatures on pyrochar formation.
abstract: Digestate from anaerobic digestion of biomass often contains more than 90% of water, which is economically unfavorable for pyrolysis. Hydrothermal carbonization (HTC) has potential to treat very wet biomass, however, the hydrochar may be acidic, contains polycyclic aromatic hydrocarbons (PAH) and toxic organic substances (e.g., phenolic compounds), and has very low Brunauer-Emmett-Teller (BET) surface area. In this study, pyrolysis of digestate derived hydrochar is performed at various pyrolysis and HTC temperatures. Solid chars were characterized for elemental analysis, pH, PAH, BET, pore size and volume, and phenolic substances, while HTC process liquids were characterized for pH, organic acids, furfural derivatives, and phenolic substances. Physicochemical characteristics of pyro-HTC char were compared with corresponding pyrochar and hydrochar. Pyro-HTC chars produced at higher HTC (i.e., 260°C) and pyrolysis temperatures (i.e., 800°C) showed highest BET surface area (63.5m(2)g(-1)), no PAH, relatively mild basic pH (9.34), and no phenolic compounds.
authors: Institute for Sustainable Energy and the Environment, 1 Ohio University, Athens, OH 45701, USA. Electronic address: garlapal@ohio.edu.
authors: Ravinder K
authors: RK
authors: Garlapalli
authors: Leibniz Institute for Agricultural Engineering, Max-Eyth-Allee 100, Potsdam 14469, Germany; German Biomass Research Centre, Torgauer Straße 116, Leipzig 04347, Germany.
authors: Benjamin
authors: B
authors: Wirth
authors: Institute for Sustainable Energy and the Environment, 1 Ohio University, Athens, OH 45701, USA; Department of Mechanical Engineering, 1 Ohio University, Athens, OH 45701, USA.
authors: M Toufiq
authors: MT
authors: Reza
mesh_terms: D001673:Biodegradation, Environmental; D018533:Biomass; D002244:Carbon / Q000737:chemistry; D002606:Charcoal / Q000737:chemistry; D013696:Temperature
chemical_list: D002606:Charcoal; D002244:Carbon
keywords: Biochar; Digestate; Hydrothermal carbonization; PAH; Pyrolysis; Surface area