A new type of scalable MFC was developed based on using alternating graphite fiber brush array anode modules and dual cathode modules in order to simplify construction, operation, and maintenance of the electrodes. The modular MFC design was tested with a single (two-sided) cathode module with a specific surface area of 29 m2 m−3 based on a total liquid volume (1.4 L; 20 m2 m−3 using the total reactor volume of 2 L), and two brush anode modules. Three different types of spacers were used in the cathode module to provide structural stability, and enhance air flow relative to previous cassette (combined anode–cathode) designs: a low-profile wire spacer; a rigid polycarbonate column spacer; and a flexible plastic mesh spacer. The best performance was obtained using the wire spacer that produced a maximum power density of 1100 ± 10 mW m−2 of cathode (32 ± 0.3 W m−3 based on liquid volume) with an acetate-amended wastewater (COD = 1010 ± 30 mg L−1), compared to 1010 ± 10 mW m−2 for the column and 650 ± 20 mW m−2 for the mesh spacers. Anode potentials were unaffected by the different types of spacers. Raw domestic wastewater produced a maximum of 400 ± 8 mW m−2 under fed batch conditions (wire-spacers), which is one of the highest power densities for this fuel. Over time the maximum power was reduced to 300 ± 10 mW m−2 and 275 ± 7 mW m−2 for the two anode compartments, with only slightly less power of 250 ± 20 mW m−2 obtained under continuous flow conditions. In fixed-resistance tests, the average COD removal was 57 ± 5% at a hydraulic retention time of 8 h. These results show that this modular MFC design can both simplify reactor construction and enable relatively high power generation from even relatively dilute wastewater.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): KUS-I1-003-13
Acknowledgements: The authors thank David Jones for help with the manufacture of the reactor and analytical measurements. This research was supported by the Strategic Environmental Research and Development Program (SERDP), Award KUS-I1-003-13 from the King Abdullah University of Science and Technology (KAUST), the State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (Grant No. 2013DX08), the National Natural Science Fund for Distinguished Young Scholars (Grant No. 51125033), Funds for Creative Research Group of China (Grant No. 51121062), an international collaborative project between China and Canada (2011DFG93360), National Natural Science Foundation of China (Grant No. 51408336, to X. Z.), and a scholarship (No. 201206120191) to W. H. from the China Scholarship Council (CSC).
This publication acknowledges KAUST support, but has no KAUST affiliated authors.