title: High-rate anaerobic co-digestion of kraft mill fibre sludge and activated sludge by CSTRs with sludge recirculation.
abstract: Kraft fibre sludge from the pulp and paper industry constitutes a new, widely available substrate for the biogas production industry, with high methane potential. In this study, anaerobic digestion of kraft fibre sludge was examined by applying continuously stirred tank reactors (CSTR) with sludge recirculation. Two lab-scale reactors (4L) were run for 800days, one on fibre sludge (R1), and the other on fibre sludge and activated sludge (R2). Additions of Mg, K and S stabilized reactor performance. Furthermore, the Ca:Mg ratio was important, and a stable process was achieved at a ratio below 16:1. Foaming was abated by short but frequent mixing. Co-digestion of fibre sludge and activated sludge resulted in more robust conditions, and high-rate operation at stable conditions was achieved at an organic loading rate of 4g volatile solids (VS)L(-1)day(-1), a hydraulic retention time of 4days and a methane production of 230±10NmL per g VS.
authors.affiliation: Department of Thematic Studies, Environmental Change, Linköping University, 581 83 Linköping, Sweden. Electronic address: eva-maria.ekstrand@liu.se.
authors.forename: Eva-Maria
authors.initials: EM
authors.lastname: Ekstrand
authors.affiliation: Scandinavian Biogas Fuels AB, Holländargatan 21A, 111 60 Stockholm, Sweden. Electronic address: marielle.karlsson@scandinavianbiogas.com.
authors.forename: Marielle
authors.initials: M
authors.lastname: Karlsson
authors.affiliation: Scandinavian Biogas Fuels AB, Holländargatan 21A, 111 60 Stockholm, Sweden. Electronic address: xubin.truong@scandinavianbiogas.com.
authors.forename: Xu-Bin
authors.initials: XB
authors.lastname: Truong
authors.affiliation: Department of Thematic Studies, Environmental Change, Linköping University, 581 83 Linköping, Sweden. Electronic address: annika.bjorn@liu.se.
authors.forename: Annika
authors.initials: A
authors.lastname: Björn
authors.affiliation: Scandinavian Biogas Fuels AB, Holländargatan 21A, 111 60 Stockholm, Sweden. Electronic address: anna.karlsson@scandinavianbiogas.com.
authors.forename: Anna
authors.initials: A
authors.lastname: Karlsson
authors.affiliation: Department of Thematic Studies, Environmental Change, Linköping University, 581 83 Linköping, Sweden. Electronic address: bo.svensson@liu.se.
authors.forename: Bo H
authors.initials: BH
authors.lastname: Svensson
authors.affiliation: Department of Thematic Studies, Environmental Change, Linköping University, 581 83 Linköping, Sweden; Scandinavian Biogas Fuels AB, Holländargatan 21A, 111 60 Stockholm, Sweden. Electronic address: jorgen.ejlertsson@scandinavianbiogas.com.
authors.forename: Jörgen
authors.initials: J
authors.lastname: Ejlertsson
mesh_terms: D000693:Anaerobiosis; D019149:Bioreactors; D007220:Industrial Waste / Q000032:analysis*; D010209:Paper; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D007220:Industrial Waste
keywords: Activated sludge; Anaerobic digestion; Fibre sludge; High-rate CSTR; Pulp and paper; Sludge recirculation