Microbial carbon capture cell using cyanobacteria for simultaneous power generation, carbon dioxide sequestration and wastewater treatment

Microbial carbon capture cells (MCCs) were constructed with cyanobacteria growing in a photo biocathode in dual-chambered flat plate mediator-less MFCs separated by an anion exchange membrane from the anode compartment containing Shewanella putrefaciens. The performance of the MCC with Anabaena sparged with CO2–air mixture was compared with that of a conventional cathode sparged with air only. The power densities achieved were 57.8 mW/m2 for Anabaena sparged with a CO2–air mixture, 39.2 mW/m2 for CO2–air mixture sparging only, 29.7 mW/m2 for Anabaena sparged with air, and 19.6 mW/m2 for air sparging only. The pH of the cathode containing Anabaena gradually increased from 7 to 9.12 and power generation decreased from 34.7 to 23.8 mW/m2 17 due to pH imbalance associated voltage losses without CO2–air mixture sparging. Sparging with a 5% CO2–air mixture produced maximum power of 100.1 mW/m2. In addition, the power density of MCC increased by 31% when nitrate was added into the catholyte.