Cost-effective Chlorella biomass production from dilute wastewater using a novel photosynthetic microbial fuel cell (PMFC).
While microalgae have been suggested as a promising substitute to conventional fossil fuels, their cost effective cultivation and harvesting constitutes a major challenge. In the work described here, a novel photosynthetic microbial fuel cell (PMFC) in which a stainless steel mesh with biofilm formed on it serves as both the cathode and filtration material has been developed. Results of this study reveal that, in addition to inducing oxygen reduction reactions under illumination, the biocathode is effective in preventing the washout of algae during continuous operation, resulting in retained biomass concentrations reaching 3.5-6.5 g L-1. The maximum output current density reached ∼200 mA m-2under irradiation, which is comparable with recent PMFC studies. Microbial diversity analyses targeting 16S and 18S rRNA genes indicated that the eukaryotic species belonging to the genus Chlorella was able to sustain its community dominance (>96%) over other competing species over the course of the studies. In the absence of catalysts such as Pt, a consortium of photosynthetic organisms including plant growth-promoting bacteria such as Azospirillum and Rhizobium were overrepresented in the biofilm, with these organisms most likely contributing to cathodic electron transfer. Energy flow analysis suggested that the PMFC system held the potential to achieve theoretical energy balance in simultaneous algae production and wastewater treatment.
State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai, 200092, PR China; School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia. Electronic address: jinxing.ma@unsw.edu.au.
Jinxing
J
Ma
State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai, 200092, PR China. Electronic address: zwwang@tongji.edu.cn.
Zhiwei
Z
Wang
State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai, 200092, PR China. Electronic address: 1432907@tongji.edu.cn.
Junyao
J
Zhang
School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia. Electronic address: d.waite@unsw.edu.au.
T David
TD
Waite
State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai, 200092, PR China. Electronic address: wuzhichao@tongji.edu.cn.
Zhichao
Z
Wu
D001674:Bioelectric Energy Sources / Q000382:microbiology*; D018533:Biomass; D002708:Chlorella; D004566:Electrodes; D010788:Photosynthesis; D062065:Wastewater
D062065:Wastewater
Algae; Energy production; Microbial diversity; Photosynthetic microbial fuel cell; Wastewater treatment