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CO2 Fixation, Lipid Production, and Power Generation by a Novel Air-Lift-Type Microbial Carbon Capture Cell System

Hu, Xia, Liu, Baojun, Zhou, Jiti, Jin, Ruofei, Qiao, Sen, Liu, Guangfei
Environmental Science & Technology 2015 v.49 no.17 pp. 10710-10717
alkaline phosphatase, biodiesel, carbon, carbon dioxide, carbon dioxide fixation, cathodes, chemical oxygen demand, energy balance, lipids, municipal wastewater, nutrients, photobioreactors, power generation, wastewater treatment
An air-lift-type microbial carbon capture cell (ALMCC) was constructed for the first time by using an air-lift-type photobioreactor as the cathode chamber. The performance of ALMCC in fixing high concentration of CO₂, producing energy (power and biodiesel), and removing COD together with nutrients was investigated and compared with the traditional microbial carbon capture cell (MCC) and air-lift-type photobioreactor (ALP). The ALMCC system produced a maximum power density of 972.5 mW·m–³ and removed 86.69% of COD, 70.52% of ammonium nitrogen, and 69.24% of phosphorus, which indicate that ALMCC performed better than MCC in terms of power generation and wastewater treatment efficiency. Besides, ALMCC demonstrated 9.98- and 1.88-fold increases over ALP and MCC in the CO₂ fixation rate, respectively. Similarly, the ALMCC significantly presented a higher lipid productivity compared to those control reactors. More importantly, the preliminary analysis of energy balance suggested that the net energy of the ALMCC system was significantly superior to other systems and could theoretically produce enough energy to cover its consumption. In this work, the established ALMCC system simultaneously achieved the high level of CO₂ fixation, energy recycle, and municipal wastewater treatment effectively and efficiently.