Two combined processes were studied in order to produce second generation biofuels: microalgae biomass production and its further use to produce biogas. Two 5 L photobioreactors for treating wastewater from a potato processing industry (from now on RPP) and from a treated liquid fraction of pig manure (from now on RTE) were inoculated with Chlorella sorokiniana and aerobic bacteria at 24 +/- 2.7 degrees C and 6000 lux for 12 h per day of light supply. The maximum biomass growth was obtained for RTE wastewater, with 26.30 mg dry weight L-1 d(-1). Regarding macromolecular composition of collected biomass, lipid concentration reached 30.20% in RPP and 4.30% in RTE. Anaerobic digestion results showed that methane yield was highly influenced by substrate/inoculum ratio and by lipids concentration of the biomass, with a maximum methane yield of 518 mL CH4 g CODadded-1 using biomass with a lipid content of 30% and a substrate/inoculum ratio of 0.5. (C) 2012 Elsevier Ltd. All rights reserved.