title: A comparison of product yields and inorganic content in process streams following thermal hydrolysis and hydrothermal processing of microalgae, manure and digestate.
abstract: Thermal hydrolysis and hydrothermal processing show promise for converting biomass into higher energy density fuels. Both approaches facilitate the extraction of inorganics into the aqueous product. This study compares the behaviour of microalgae, digestate, swine and chicken manure by thermal hydrolysis and hydrothermal processing at increasing process severity. Thermal hydrolysis was performed at 170°C, hydrothermal carbonisation (HTC) was performed at 250°C, hydrothermal liquefaction (HTL) was performed at 350°C and supercritical water gasification (SCWG) was performed at 500°C. The level of nitrogen, phosphorus and potassium in the product streams was measured for each feedstock. Nitrogen is present in the aqueous phase as organic-N and NH3-N. The proportion of organic-N is higher at lower temperatures. Extraction of phosphorus is linked to the presence of inorganics such as Ca, Mg and Fe in the feedstock. Microalgae and chicken manure release phosphorus more easily than other feedstocks.
authors.affiliation: School of Chemical and Process Engineering, University of Leeds, LS2 9JT Leeds, United Kingdom.
authors.forename: U
authors.initials: U
authors.lastname: Ekpo
authors.affiliation: School of Chemical and Process Engineering, University of Leeds, LS2 9JT Leeds, United Kingdom.
authors.forename: A B
authors.initials: AB
authors.lastname: Ross
authors.affiliation: Institute for Public Health and Environmental Engineering, School of Civil Engineering, University of Leeds, LS2 9JT Leeds, United Kingdom; Departamento de Ingeniería Química, Universidad Nacional de Colombia, Campus La Nubia, Manizales, Colombia.
authors.forename: M A
authors.initials: MA
authors.lastname: Camargo-Valero
authors.affiliation: School of Chemical and Process Engineering, University of Leeds, LS2 9JT Leeds, United Kingdom.
authors.forename: P T
authors.initials: PT
authors.lastname: Williams
mesh_terms: D000818:Animals; D018533:Biomass; D002244:Carbon / Q000032:analysis; D002645:Chickens; D002708:Chlorella / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007287:Inorganic Chemicals / Q000032:analysis*; D008372:Manure / Q000032:analysis*; D058086:Microalgae / Q000378:metabolism*; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D011188:Potassium / Q000032:analysis; D013552:Swine; D013696:Temperature; D014866:Waste Products; D014867:Water / Q000737:chemistry*
chemical_list: D007287:Inorganic Chemicals; D008372:Manure; D014866:Waste Products; D014867:Water; D010758:Phosphorus; D002244:Carbon; D009584:Nitrogen; D011188:Potassium
keywords: Digestate; Hydrothermal processing; Manure; Microalgae; NPK