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Research article2020Peer reviewedOpen access

Co-digestion of salix and manure for biogas: importance of clone choice, coppicing frequency and reactor setup

Ohlsson, Jonas; Rönnberg Wästljung, Ann-Christin; Nordh, Nils-Erik; Schnürer, Anna


Animalmanure represents amajor source of renewable energy that can be converted into biogas
using anaerobic digestion. In order to most efficiently utilize this resource, it can be co-digested with
energy dense, high biomethanation potential feedstocks such as energy crops. However, such feedstocks
typically require pretreatments which are not feasible for small-scale facilities.We investigated the
use of single-stage and the sequential co-digestion of comminuted but otherwise non-pretreated Salix
with animal manure, and further investigated the effects of coppicing frequency and clone choice on
biomethanation potential and the area requirements for a typical Swedish farm-scale anaerobic digester
using Salix and manure as feedstock. In comparison with conventional single-stage digestion, sequential
digestion increased the volumetric and specific methane production by 57% to 577 NmL L􀀀1 d􀀀1 and
192 NmL (g volatile solids (VS))􀀀1, respectively. Biomethanation potential was the highest for the twoyear-
old shoots, although gains in biomass productivity suggest that every-third-year coppicing may
be a better strategy for supplying Salix feedstock for anaerobic digestion. The biomethane production
performance of the sequential digestion of minimally pretreated Salix mirrors that of hydrothermally
pretreated hardwoods and may provide an option where such pretreatments are not feasible.


anaerobic digestion; co-digestion; energy crops; manure; Salix

Published in

2020, Volume: 13, number: 15 , article number: 3804