| Utilising CO2 from biogas as a carbon source can introduce energy production systems incorporatingmicroalgae cultivation into wastewater treatment plants (WWTPs). In this study, the effects of utilisingmembrane-separated CO2 (MSC; CO2 content: 983 ± 11 dm3 m 3)dobtained from biogas using a newlydeveloped separation systemdon indigenous microalgae cultivation with treated effluents was investigated.Assuming model cultivation systems, energy balance analysis was conducted to evaluate thefeasibility of MSC utilisation and its superiority over flue gas CO2 (FC) from power plants (PPs). Scenarios1 and 2 used generated biogas of 11.6 and 116 dm3 s 1, and produced MSC (carbon based) were 0.802 and8.02 g s 1, respectively. Experiments comparing MSC (suspended solids (SS): 166 ± 23 mg dm 3; higherheating value (HHV): 21.1 ± 0.46 kJ g 1) with commercial CO2 (SS: 176 ± 16 mg dm 3; HHV:21.2 ± 0.90 kJ g 1) revealed no negative effects on microalgae activity, biomass production, or energycontent. Energy revenue of the MSC utilisation system was 27.0 MJ per 1 kg injected MSC, which isgreater than the energy costs (18.2 and 17.1 MJ kg 1 in scenarios 1 and 2, respectively). MSC utilisation isenergetically feasible, and energetically superior to FC utilisation when the PP-to-WWTP distance is over0.6 and 1.9 km in scenarios 1 and 2, respectively. |
