Search

[Display omitted] • Saline microalgae biomass was used to investigate saline anaerobic digestion. • Inoculum used to treat non-saline sewage sludge was acclimated to 14 g·L-1 salinity. • CH 4 production was not impacted by salinity after 10 weeks of semi-continuous test. • Salinity causing 50 % inhibition of CH 4 production was 27 g·L-1 after acclimation. • The population of methylotrophic methanogens increased with salt acclimation. The aim of this study was to acclimate anaerobic prokaryotes to saline microalgae biomass. Semi-continuous experiments were conducted using two 1.5 L mesophilic reactors for 10 weeks, (hydraulic retention time of 21 days). The first reactor was solely fed with sewage sludge (control), while the second received a mixture of sewage sludge and microalgal biomass (80/20 %w/w) cultivated at 70 g·L-1 salinity. The in-reactor salinity reached after the acclimation phase was 14 g·L-1. Biomethane production was comparable between the control and acclimated reactors (205 ± 29 NmL Methane ·g VolatileSolids -1). Salinity tolerance assessment of methanogenic archaea revealed that salinity causing 50% inhibition of methane production increased from 10 to 27 g·L-1 after acclimation. Microbial diversity analyses revealed notable changes in methanogenic archaea populations during co-digestion of saline microalgae biomass, particularly methylotrophic (+27%) and acetotrophic (-26%) methanogens. This study has highlighted the possibility of treating efficiently saline microalgae in co-digestion with sewage sludge in future industrial biogas plants. [ABSTRACT FROM AUTHOR]