Biochar-alginate jointly immobilized Chlorella vulgaris in cathode enhanced power generation in photo microbial fuel cells

The present research investigated for the first time the performance of photo microbial fuel cells (photo-MFCs) with biochar-alginate joint immobilized Chlorella vulgaris (BAJIC) as a cathodic microorganism. The results showed the stabilized voltage output reach 0.182 V in photo-MFCs with BAJIC, which is 61.1 % higher than that of the alginate immobilized C. vulgaris and 2.43 times that of suspended C. vulgaris. Light intensity affected both the cathodic potential and internal resistance of the photo-MFCs with BAJIC. The cathodic potential increased from −0.258 to −0.173 V (vs. Ag/AgCl) when the light intensity was increased from 1500 to 2500 lx. Meanwhile, the internal resistance decreased from 583.88 to 392.51 Ω. The results also showed that BAJIC with the smaller bead diameter generated larger voltage. BAJIC dosage affected the voltage of the increasing stage, while did not influence the stable voltage. This work demonstrated that biochar, as an efficient additive to the alginate immobilized microalgae beads, can boost the performance of microalgae matrix, and thus provide an economical and effective approach to enhance the efficiency of photo-MFCs.