There is growing interest to produce fuels from algae, namely the third generation biofuel. Galactose and glucose are basic chemicals for many red macroalgae, but fermentation of the mixed sugars may suffer significant glucose repression using yeast. Therefore, another fermentation, acetone-butanol-ethanol (ABE) fermentation of the mixed sugars was studied using Clostridium acetobutylicum and Clostridium beijerinckii. Both strains can use either galactose or glucose, and showed an optimal pH at ~ 5.0. Co-fermentation of the mixed sugar showed simultaneous consumption of glucose and galactose, and exhibited solvent production of 4.19 and 4.57 g/L using Clostridium acetobutylicum and Clostridium beijerinckii, respectively. The fermentation can become more industrially practical if improvement in galactose consumption can be further improved in the future.

Microbial fuel cells (MFCs) are a potential biotechnology for simultaneous degradation of organic wastewater and power generation. In this paper, a biocompatible composite is constructed around a copper mesh with sodium alginate/agar and activated carbon (CM‐SA/AC) and acts as an efficient anode for MFCs after being microbe immobilized. The power performance of the MFC with CM‐SA/AC anode is investigated. The results show that the addition of activated carbon is conducive to the immobilization of bacteria on CM‐SA/AC anode and fast start‐up of MFCs. The power density reaches 1088.6 mW/m2, which is 2.03 times and 1.75 times that of CM‐SA (without activated carbon) anode and carbon felt anode, respectively. In case of a candied wastewater treatment, the MFC with immobilized CM‐SA/AC anode exhibits a much higher power density (724.5 mW/m2) than that with carbon felt anode (145.0 mW/m2), together with a longer stabilization time and a smaller charge‐transfer resistance. The total removal rate of chemical oxygen demand (COD) reaches 79.4 ± 0.65%. The present study will facilitate the development of inexpensive and biocompatible anodes to facilitate the application of MFCs in wastewater treatment.