Supplementary Material for:
Electricity Generation from Mixed Volatile Fatty AcidsUsing Microbial Fuel Cells
Shao-Xiang Teng1,2, Zhong-Hua Tong1,*, Wen-Wei Li1, Shu-Guang Wang2, **, Guo-Ping Sheng1,Xian-Yang Shi3, Xian-Wei Liu1, Han-Qing Yu1
1Department of Chemistry, University of Science & Technology of China, Hefei, 230026,China
2School of Environmental Science and Engineering, ShandongUniversity, Jinan, 250100, China
3Institute of Life Sciences, AnhuiUniversity, Hefei,Anhui 230039, China
*Corresponding authors:
*Zhong-Hua Tong,Fax: +86 551 3601592; E-mail: ;
** Shu-Guang Wang, Fax: +86 531 88364513; E-mail:
List of Content
Page S3 ---- Table S1Summary of DGGE bands identifications
Page S4 ---- Fig. S1Configuration of the single-chamber air-cathode MFCs
Page S5 ---- Fig. S2Simplex-centroid design of mixed VFAs
Page S6 ---- Fig.S3 Responses of power density and coulombic efficiency toward the composition of mixed VFAs examined using Minitab. D: composite desirablility; PD: power density; CE: coulombic efficiency; Current VFAs fraction:acetate 0.556, propionate 0.1264, butyrate 0.3176, shown in red in the first row; y is related PD or CE values shown in blue; The red vertical line indicates the fraction of each acid; The blue horizontal dash line indicates the dependent response of PD or CE.
Page S7 ---- An example on how to examine the responses of power density and coulombic efficiency toward the composition of mixed VFAs using Minitab.
Table S1 Summary of DGGE bands identifications
Band(Genbankaccession number) / Class1 / GenBank closest match2 / Identity (%)A(GQ463149) / Bacteroidetes / Uncultured Petrimonas sp. ( FJ262571) / 100
B (GQ478196) / Betaproteobacteria / Hydrogenophaga sp. enrichment culture clone ( EU834841) / 97
C (GQ478197) / Bacteroidetes / Uncultured bacterium clone MFC-A26 ( FJ262588) / 100
D (GQ478198) / Deltaproteobacteria / Uncultured bacterium clone MFC-GIST439 ( EU704648) / 99
E (GQ478199) / Bacteroidetes / Flavobacterium-like sp. oral clone AY017 ( AF385544) / 100
F (GQ478200) / Firmicutes / Uncultured Trichococcus sp. clone A12 ( GQ249358) / 100
G (GQ478201) / Deltaproteobacteria / Uncultured bacterium clone MFC-GIST439 ( EU704648) / 97
H (GQ478202) / Bacteroidetes / Uncultured bacterium gene for 16S rRNA ( AB195878) / 98
I (GQ478203) / Betaproteobacteria / Uncultured bacterium clone MFC-GIST220 ( EU704584) / 98
J (GQ478204) / Actinobacteria / Gordonia sp. W-JS-1 16S ribosomal RNA gene ( FJ529036) / 100
K (GQ478205) / Flavobacteria / Uncultured bacterium gene for 16S rRNA ( AB364392) / 98
L (GQ478206) / Betaproteobacteria / Uncultured bacterium clone nbw285d04c1 ( GQ086079) / 98
M (GQ478207) / Bacteroidetes / Uncultured bacterium gene,clone: MBF16_F ( AB290389) / 100
N (GQ478208) / Bacteria / Uncultured Thermotogae 16S rRNA gene ( CU923080) / 100
1 based on RDP query results
2 based on closest BLAST homology results
Fig. S1 Configuration of the single-chamber air-cathode MFCs
Fig. S2Simplex-centroid design of mixed VFAs
Fig.S3Responses of power density and coulombic efficiency toward the composition of mixed VFAsexamined using Minitab. D: composite desirablility; PD: power density; CE: coulombic efficiency; Current VFAs fraction:acetate 0.556, propionate 0.1264, butyrate 0.3176, shown in red in the first row; y is related PD or CE values shown in blue; The red vertical line indicates the fraction of each acid; The blue horizontal dash line indicates the dependent response of PD or CE.
An example on how to examine the responses of power density and coulombic efficiency toward the composition of mixed VFAs using Minitab.
To examine the response of MFC performance towards the composition of mixed VFAs, dynamic changes of power density (PD) and coulombic efficiency (CE) were examined using the Minitab software. An example of this method to analyze one set of VFAs composition (acetate 0.554, propionate 0.1264, butyrate 0.3176) is depicted in Fig. S3. In the first row, the high and low fractions of each acid are listed, and the red numbers are the fraction of each acid of this example. Desirability (d) is defined as the ratio of the present response to the maximum response, which is 0.2739 and 0.8086 for PD and CE, respectively. In the first column, the D value 0.47058 is composite desirability, which is the desirability of PD and CE with equal weight. The red vertical lines indicate the fractions of each acid, while the blue horizontal dash lines and blue character “y” indicate the response values of PD and CE, which are plotted as black curves when the fraction of different fatty acids is increased in the dynamic mode. When we move the red line in the second column from left to right, the percentage of acetate (HAc) changes from 0.43 to 0.86 (the exact values are shown in red in the first row). Meanwhile, the blue dash lines will move accordingly, corresponding to the changes in coulombic efficiency and power density. In this way, the composite desirability can be calculated.
Fig. 3 and Fig. S3 show that the power density was sensitive to the fraction of acetate and that the coulombic efficiency was more sensitive to butyrate. Within a range of 43-86%, the power density increased as the proportion of acetate increased. Propionate less than 12% showed a positive impact on the power density, while 17% caused a decrease. A decrease in power density was observed when butyrate exceeded 24%. As for the coulombic efficiency, it increased with the increasing acetate proportion. A high coulombic efficiency (>36%) could be achieved when acetate accounted for 60-67% of the mixed VFAs. As acetate proportion increased further, however, the resulting coulombic efficiency decreased by ca. 2% decrease. Such a slight decrease might be resulted from the interaction between acetate and propionate or the modeling bias. Changes in propionate proportion within the examined range did not cause much variation in coulombic efficiency. Compared with acetate and propionate, the coulombic efficiency was more sensitive to the proportion of butyrate. A drastic drop in coulombic efficiency occurred when butyrate exceeded 26%.
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