Biogas Production from Microalgae (Spirulina platensis) in a Two Stage Anaerobic System

In this study, utilization of blue green algae Spirulina platensis as a renewable energy source was investigated in batch and semi-continuous systems. In batch studies 89-93 % volatile solids (VS) reductions were achieved under initial total solids concentrations of 0.6-5 %. The corresponding biogas production was between 210 and 260 mL/gVS. In the continuous studies two-phase anaerobic digestion system was investigated. During first part biogas production from sewage sludge was investigated under total hydraulic retention time of 14 days. The system achieved 60 % VS reductions with 2620 mL biogas/day (525 mL biogas/gVS day). Co-digestion of waste sewage sludge with S. platensis improved biogas production and VS reductions. During this operation 62.5 % VS reductions was achieved with 2880 mL/day total biogas production (640 mL biogas/gVS day).