title: Anaerobic digestion of alkaline bleaching wastewater from a kraft pulp and paper mill using UASB technique.
abstract: Anaerobic digestion of alkaline kraft elemental chlorine-free bleaching wastewater in two mesophilic, lab-scale upflow anaerobic sludge bed reactors resulted in significantly higher biogas production (250±50 vs. 120±30 NmL g [Formula: see text]) and reduction of filtered total organic carbon (fTOC) (60±5 vs. 43±6%) for wastewater from processing of hardwood (HW) compared with softwood (SW). In all cases, the gas production was likely underestimated due to poor gas separation in the reactors. Despite changes in wastewater characteristics, a stable anaerobic process was maintained with hydraulic retention times (HRTs) between 7 and 14 h. Lowering the HRT (from 13.5 to 8.5 h) did not significantly affect the process, and the stable performance at 8.5 h leaves room for further decreases in HRT. The results show that this type of wastewater is suitable for a full-scale implementation, but the difference in methane potential between SW and HW is important to consider both regarding process dimensioning and biogas yield optimization.
authors.affiliation: a Department of Thematic Studies, Environmental Change , Linköping University , 581 83 Linköping , Sweden.
authors.forename: Madeleine
authors.initials: M
authors.lastname: Larsson
authors.forename: Xu-Bin
authors.initials: XB
authors.lastname: Truong
authors.forename: Annika
authors.initials: A
authors.lastname: Björn
authors.forename: Jörgen
authors.initials: J
authors.lastname: Ejlertsson
authors.forename: David
authors.initials: D
authors.lastname: Bastviken
authors.forename: Bo H
authors.initials: BH
authors.lastname: Svensson
authors.forename: Anna
authors.initials: A
authors.lastname: Karlsson
mesh_terms: D000693:Anaerobiosis; D056804:Biofuels; D019149:Bioreactors; D057886:Bleaching Agents; D006863:Hydrogen-Ion Concentration; D010209:Paper; D062065:Wastewater; D014934:Wood
chemical_list: D056804:Biofuels; D057886:Bleaching Agents; D062065:Wastewater
keywords: UASB; alkaline kraft ECF bleaching wastewater; anaerobic digestion; hardwood; softwood