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Sustainable operation of osmotic microbial fuel cells through effective reproduction of polyelectrolyte draw solutes facilitated by cathodic pH increase
- Yang, Yuli, Qin, Mohan, Yang, Xiaoli, He, Zhen
- Journal of cleaner production 2017 v.168 pp. 1143-1149
- bioenergy, electrolytes, microbial fuel cells, osmosis, pH, polyacrylic acid, salts, sodium, solutes, wastewater treatment
- Osmotic microbial fuel cells (OsMFCs) take advantages of synergy between forward osmosis (FO) and microbial fuel cells (MFCs) for simultaneous wastewater treatment, bioenergy production, and water recovery. A unique feature for healthy operation of OsMFCs is an appropriate draw solute (DS) that can also act as a catholyte. Herein, polyelectrolytes (polyacrylic acid sodium salts, PAA-Na) was investigated as a DS/catholyte and reproduced with the aid of the high catholyte pH. Such a reproduction method is innovative, because it turns a drawback (high catholyte pH) into a useful resource, thereby reducing the demand for external input and leading to a clean production process. The results have showed that the OsMFC achieved a current density of 159 ± 6 A m⁻³, water flux of 12.7 ± 0.2 LMH, and low reverse salt flux of 0.05 ± 0.00 gMH with 32 wt% PAA-Na (2000 Da) as the DS. The DS recovery efficiency could be as high as 99.86 ± 0.04%, and the reproduced DS was successfully applied in the subsequent operation. With this reproduction method, the highest total operation cost was estimated at 0.104 $ m⁻³. Those results have demonstrated a new approach based on pH-dependent PAA DS reproduction towards further development of OsMFC technology for sustainable water/wastewater treatment and resource recovery.