Electricity generation from sugarcane molasses using microbial fuel cell technologies

Accepted Manuscript Electricity Generation from Sugarcane Molasses Using Microbial Fuel Cell Technologies

Sedky H.A. Hassan, Abd El-Naser A. Zohri, Rehab M.F. Kassim PII:

S0360-5442(19)30720-0

DOI:

10.1016/j.energy.2019.04.087

Reference:

EGY 15116

To appear in:

Energy

Received Date:

02 April 2018

Accepted Date:

15 April 2019

Please cite this article as: Sedky H.A. Hassan, Abd El-Naser A. Zohri, Rehab M.F. Kassim, Electricity Generation from Sugarcane Molasses Using Microbial Fuel Cell Technologies, Energy (2019), doi: 10.1016/j.energy.2019.04.087

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Research Article:

Electricity Generation from Sugarcane Molasses Using Microbial Fuel Cell Technologies Sedky H. A. Hassan1* Abd El-Naser A. Zohri2, and Rehab M. F. Kassim3 1

Botany and Microbiology, Faculty of Science, New Valley University, 72511, El-Kharga,

Egypt. 2Botany

and Microbiology Department, Faculty of Science, Assiut University, Assiut, Egypt.

3 Industrial

fermentation department, Sugar Technology Research Institute (STRI), Assiut

University, Assiut, Egypt

Running Title: Electricity generation from molasses by bacteria *Address for correspondence: Sedky H. A. Hassan Botany & Microbiology Department, Faculty of Science, New Valley University, El-Kharga, 72511, Egypt. Phone: +201020526488 E-mail: [email protected]

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Abstract This work demonstrated the possibility of bioelectricity generation using microbial fuel cell technologies from sugarcane molasses by a bacterial strain isolated from molasses. The strain identified according to 16S rRNA as Brevibacillus borstelensis STRI1. Sugarcane molasses could be used as a substrate in MFC, because of its high sugar content. When the bacterial strain was used as biocatalyst and sugarcane molasses as a substrate in MFC. The voltage increased rapidly over time recording 990 ±5 mV in open circuit voltage (OCV), and 453±6 mV in closed circuit voltage (1000 Ω) after 10 days of operation. The power density (Pmax) determined from the polarization curve, and it was 188.5 mW/m2 with an initial concentration of sugarcane molasses 1 ml (1632 mg/L as COD). While the coulombic efficiencies (CEs) ranged from 59.8 to 28.03%, related to initial concentrations of 0.3±0.05 to 2.0 ± 0.15 g/L. The COD removal was determined and it was 11.7 % after 5 days and reached to 81.7 % by the end of the operation (30 days). These results suggested that bioelectricity could be generated from sugarcane molasses by Brevibacillus borstelensis STRI1. Key words: Bioelectricity generation; Microbial fuel cells; Sugarcane molasses; Brevibacillus borstelensis

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Introduction Fossil fuels are the main energy sources for the motorization, and industrialization over the world. According to the production and rates of consumption, the reserves of fossil fuels will not totally run out for less than 100 years [1]. The increase in prices of petroleumbased fuels and environmental pollution issues have encouraged research into the development of biofuel technology from sustainable resources which could substitute for fossil fuels [2]. Thus, there is a demand to find out sustainable and clean energy source with minimal air pollution [3, 4]. Electricity production from renewable materials by microorganisms is considered a sustainable alternative energy for future and industrial biotechnology. Microorganisms could be used to catalyze the conversion of organic matter, present in the agro-industrial wastes, into electricity [5, 6]. Microbial fuel cell (MFC) is an innovative environmental energy system that convert organic wastewater into bioelectricity using microorganisms [3-5]. A typical MFC is composed of two electrodes, a proton exchange membrane (PEM), an oxidation-reduction reaction between the organic substrates and the microorganisms [7-11]. Electrons produced by microorganisms from these organic substrates are transferred to the anode and protons go through PEM to the cathode chamber [6]. Transfer of electrons from microbes to the anode can occur either through different mechanisms including electron shuttles [4, 6, 12] or nanowires [13]. Different microbes have been used in MFCs including a pure culture of anaerobic or facultative anaerobes bacteria [3, 5, 6, 12, 14], or mixed culture [4, 15-19]. Electron donors which are commonly used in MFC, including simple carbohydrates or polysaccharides, amino acids, organic acids, cellulose, wastewater, marine sediments, lignocellulosic substrates [3-5, 14-20]. The 3

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power generation in MFC is depending on different factors, including MFC configuration, types of electrodes, membrane types, surface area of PEM, substrates and fuel concentration, genus and electrophilic properties of microorganisms [3-5, 15, 16, 20-22] Molasses is the by-product from sugar industry and it could be used for biofuel production [23]. Sugarcane bagasse and molasses have been used for biofuel production including bioethanol and biogas [24], biodiesel, hydrogen and methane and bio-electricity [25-27]. Indonesia is one of the experienced countries for bioethanol production from sugarcane molasses [28]. Several studies showed the sustainability of ethanol production from molasses and other agro-industrial biomass [28, 29]. MFCs provide new technology for the clean renewable energy production from biodegradable and reduced compounds, and thus, have attracted substantial research efforts to develop various devices for generating electricity and removing wastes furthermore, they have received great interest in biosensor applications [30, 31]. This study aimed to use a pure culture of Brevibacillus borstelensis STRI1 for bioelectricity generation from sugarcane molasses without using any exogenously added mediators. Materials and methods Sugarcane molasses and composition Egyptian sugarcane molasses used in this study was kindly provided by AbuQuraqas Co. Ltd. (Egypt). The chemical composition of sugarcane molasses was determined according to the association of official analytical chemists (AOAC) [32]. The chemical analysis includes pH; total solids, fermentable & non-fermentable sugars; ash and nitrogen content.

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Microorganism and identification of the isolate STRI1 The bacteria were isolated by transferring 1 ml of sugar cane molasses to 100 ml conical flask containing 25 ml liquid nutrient broth medium consisted of 10 g/L Beef extract, 5 g/L Peptone and 3 g/L NaCl [33]. Then the conical flasks were incubated at 30˚C for 48 hr. After that, 1 ml of that culture was transferred to the Petri dishes with solid nutrient agar (NA) medium and was incubated at 30˚C for 48 hr. Single producing colonies were transferred into NA for bacterial purification[33]. The pure bacterium was transferred from NA to nutrient broth medium and designated as STRI1. The culture of bacteria was incubated at 30˚C for 24hr; then, it was used as the inoculums in the MFC. The bacterial DNA was extracted and used as a template for PCR to amplify the 16S rRNA gene according to the methods described previously in Hassan et al., [34]. For identification of the isolated bacteria, the partial 16S rRNA gene sequence was compared with full sequences available in the GenBank database using a BLAST search (NCBI). MFC operation A dual chamber of two bottles (H type MFC), described well in previous studies [7-11], was used in this experiment for bioelectricity production. Phosphate buffer was used as a buffer medium in the MFCs. Sugarcane molasses was used as the carbon and electron source in the current study, bacterial isolate STRI1 was used as inoculum (2 ml), in the anode chamber (250 ml), and K3Fe(CN)6 was used as catholyte. After the decline phase and consuming of sugarcane molasses, the anode chamber was refilled again with new phosphate buffer and sugarcane molasses. Calculations 5

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The cell voltages (Volt) were measured at different loads (10-200000Ω) using a multimeter. Power (P) was calculated according to P= IV I=

(1)

𝑉 𝑅

(2)

where I (Amber) is the current, V(Volt) is the voltage, and R(Ω) is the external resistance. The power density (Pmax), and (Imax) were normalized to the anode surface area [3, 4, 15, 20]. The internal resistance (Rint) of the MFC was estimated as mentioned elsewhere [3]. The Coulombic efficiency, CE, for an MFC run in fed-batch mode, evaluated over a period of time t, is calculated as mentioned previously [3, 4, 15, 20]. Chemical oxygen demand was measured according to standard methods APHA [35]. A cyclic voltammetry (CV) was used to characterize the oxidation and reduction of the anode surface by measuring the current response at the anode surface under anaerobic conditions. A potential range of -400 mV to 1000 mV was applied. CV was performed in a specific potential range at a scan rate of 50 mV/s.

Results and discussion Chemical composition of sugarcane molasses It was found that fermentable and not fermentable sugar were 46.7 and 4.66 %, respectively and the total sugar with 51.36 %, which could be considered as a potential carbon source for many microorganisms. While total solids and ash contents were 86.67

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and 10.45 %, respectively. The density was 1.4 g/cm3 and pH was 5.1. Other chemical compositions were indicated in Table (1). Table 1 Identification of the isolate STRI1 The isolate STRI1 was grown on NB. The bacterial isolate was Gram-positive and oxidase negative. Table 2, shows the physiological and biochemical characterization of the selected strain. An isolated strain showed a positive biochemical result for, L-Arabitol (IARL), D-Glucose (dGLU ), D-Mannitol (dMAN), D-Mannose (dMNE), Sucrose (SAC), Citrate (Sodium) (CIT). Beta-Galactosidase (BGAL), L-Proline Arylamidase (ProA), Lipase (LIP), Lysine Decarboxylase (LDC), and Phosphatase (PHOS). While the test results for D-Cellobiose (dCEL), D-Maltose (dMAL), D-Sorbitol (dSOR), Urease (URE), and H2S Production (H2S) were negative. The sequence similarity of the 16SrRNA gene was compared with other data obtained from the National Center for Biotechnology Information (NCBI) website. The results revealed that the isolate STRI1 is a member of the genus Brevibacillus. Brevibacillus borstelensis was the nearest neighbor with 16S rRNA similarity of 97 %. The isolated strain was identified as Brevibacillus borstelensis STRI1. The nucleotide sequences of B. borstelensis STRI1 have been deposited in the GenBank database under accession number KY624414. The phylogenetic tree of the isolate STRI1 was shown in Figure (1). Figure 1 Table 2

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Voltage generation from sugarcane molasses using Brevibacillus borstelensis STRI1 In this study, MFC device was inoculated with a bacterial strain that have the ability to use sugarcane molasses as a carbon and nitrogen sources. The MFC containing Brevibacillus borstelensis STRI1shows an increasing in the cell voltage after addition of sugarcane molasses. After operation of MFC, the power generation was almost zero, because the microbial biofilm haven’t been developed yet on the anode surface. After that, the cell potential start increasing over time then the voltage reached a plateau at 990±5 mV in the open circuit voltage OCV and 453±6 mV in closed circuit voltage CCV (1000 Ω) after several days of running the experiment (Figure 2), which might be explained be the formation of bacterial biofilm and transferring of electrons to the anode. The results indicated that the voltage generated from sugarcane molasse could be possible by B. borstelensis STRI1 using the microbial fuel cell technologies. Also, the voltage could be generated over 30 days, after that, the voltage starts decreasing until reaches the decline phase. Once the MFC was refilled with fresh medium containing sugarcane molasses in semi batch mode, the volt was quickly reached at a stable voltage (450±7 mV) was produced without a lag phase of the cycle (Figure 2). In a previous study by Hassan et al., [17], they used cellulose degrading bacteria (CDB) as a catalyst and rice straw as a substrate in dual chamber MFC, the power reached a steady state of 145.2 mW/m2 and constant voltage of 345±12 mV. Many studies also revealed that no observation of lag phase in the second or repeated cycles after the MFC refueled again with a new medium and substrates [14, 17, 36-38]. Mathuriya and Sharma [39] reported that bioelectricity could be produced by both the microorganisms. S. cerevisae generated 4.92 mA and 8.72 mA after 4 and 9

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days, respectively and C. acetobutylicum generated 4.59 mA and 7.43 mA after 5 and 9 days of operation. Figure 2 Polarization characteristics The polarization properties of the MFC is shown in Figure 3. When the cell voltage reached a plateau in OCV, different external loaded were applied, and the power (P) was calculated. A maximum power of 0.188 mW at a current of 0.63 mA with a resistance of 1000 Ω, the Pmax, and Imax were 188.45 mW/m2 and 63mA/m2, respectively. The internal resistance (Ri) was calculated and it was approximately 740 Ω, which was in the same range of other MFCs [11, 14]. Zhang et al., [25] stated that the maximum power density generated from molasses wastewater in the UASB–MFC–BAF system over 60 days operation was 1410.2 mW/m2, with a current density of 4947.9 mA/m2. Furthermore, a power density generated from rice straw using a (CDB) was 145.2mW/m2 [14]. Table 3 compares the Pmax, substrates, and microorganisms obtained in this study with some other data reported in the literature. The power densities for the current study was found to be comparable with many of the reported literature values. The difference in values of power density could be explained by different substrates for microorganisms, MFC configuration, electrodes, and proton exchange membranes. Figure 3 Table 2 Substrate degradation and COD removal

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In the batch experiment, COD removal in the system increased continuously with time (Fig. 4). Within 5 days, it decreased from 1632 mg/L to 1440 mg/L, and the removal percentage reached 11.76 %. The percentage of COD removal increased gradually till reaching 37.8 % and COD reached to 617 mg/L after 10 days of operation. While at end of operation reached to 81.7 % (298 mg/L). These results are similar to that observed by Li et al., [40]. They revealed that percentage of COD removal of artificial wastewater reached to 88 % at the end of the operation in baffled MFCs. On the other hand, the corresponding COD removal by the mixed culture of cellulose degrading bacteria using cellulose as a substrate in two chambered MFC was 29.33 % after ten days of operation [14]. Bioelectricity production from sugarcane molasses suggesting that biodegradable organic compounds could be consumed by the bacterium Brevibacillus borstelensis STRI1for bioelectricity and COD removal. Figure 4 The coulombic efficiencies (CEs) The CEs of sugarcane molasses was determined by measuring the changes of COD over the time after the voltage of the cell decreased to less than 100 mV. The CEs in the MFC was monitored at different concentrations ranging from 0.3 ± 0.05, 0.6 ± 0.03, 1.5±0.05 to 2.0 ± 0.15 g/L. When the initial sugarcane molasses concentration increased from 0.3±0.05 to 2.0 ± 0.15 g/L, the CEs decreased from 59.87 to 28.03 %. While, it was 43.41 and 37.9 % for 0.6 ± 0.03, 1.5±0.05g/L, respectively -The differences in CE at different sugarcane molasses concentrations indicated that some electrons had been consumed by other mechanisms than power generation. In the previous study by Hassan et

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al, [17], reported the CE decreased from 54.3 % to 45.3 % for the concentration 0.5-0.1 g/L of rice straw as a substrate for electricity generation. Zhang et al. [37], reported that the CE ranged from 37.1 to 15.5, corresponding to an initial hydrolysate concentration of 250 to 2000 mg/L. Cyclic voltammetry (CV) The cyclic voltammetry (CV) was used to measures the oxidation reduction activities and the mediators bound to the bacterial cells in anodic chamber. The CV was performed in the anode medium with the culture of B. borstelensis STRI1 or without the bacterial culture. No electrochemical activity was observed in the anode medium without bacterial culture, indicating that the medium used had no effect on the CV measurement (Fig. 5). The CV plot of the anodic medium in the presence of B. borstelensis STRI1 culture was shown in Fig. 5. The reduction peak and oxidation peaks of the voltammograms were 400 mV and 290 mV, respectively. The results revealed the electrogenic activities of B. borstelensis STRI1 and the presence of redox active components which may be act as an extracellular electron transfer to the anode. Similar results was observed by Hassan et al.,[11], they reported that the CV of CDB bacteria showed a reduction and oxidation peaks at 500, 380 and 720 mV, respectively. Figure 5 Conclusions This study demonstrated that pure culture of Brevibacillus borstelensis STRI1 has the ability to produce electricity directly from sugarcane molasses. The sugarcane molasses contain fermentable and non-fermentable sugars, nitrogen compounds and other minerals 11

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which could serve as carbon and nitrogen sources for the growth of B. borstelensis STRI1. The power density reached 188.5 mW/m2 with an initial concentration of sugarcane molasses (1.15 g/L). The COD removal was determined and it was 11.7 % after 5 days and reached to 81.7 % by the end of the operation (30 days), which suggest the possibility of MFC in wastewater treatment. The coulombic efficiencies (CEs) was 59.8 % at initial concentration 0.3 ± 0.05 g/L. These results suggested that electricity could be produced from sugarcane molasses by Brevibacillus borstelensis STRI1.

Acknowledgements The authors present great thanks to Assiut University for supporting this work under its scientific projects, and to the anonymous reviewers for their valuable comments.

References [1] Goldemberg J. Ethanol for a sustainable energy future. science. 2007;315:808-10. [2] Hawkes F, Dinsdale R, Hawkes D, Hussy I. Sustainable fermentative hydrogen production: challenges for process optimisation. International Journal of Hydrogen Energy. 2002;27:1339-47. [3] Logan BE, Hamelers B, Rozendal R, Schröder U, Keller J, Freguia S, et al. Microbial fuel cells: methodology and technology. Environmental Science & Technology. 2006;40:5181-92. [4] Logan BE, Regan JM. Microbial fuel cells - Challenges and applications. Environmental Science and Technology. 2006;40:5172-80. [5] Liu H, Cheng S, Logan BE. Production of Electricity from Acetate or Butyrate Using a Single-Chamber Microbial Fuel Cell. Environmental Science & Technology. 2004;39:658-62. [6] Bond DR, Lovley DR. Electricity production by Geobacter sulfurreducens attached to electrodes. Applied and Environmental Microbiology. 2003;69:1548-55. [7] Lay C-H, Kokko ME, Puhakka JA. Power generation in fed-batch and continuous upflow microbial fuel cell from synthetic wastewater. Energy. 2015;91:235-41. [8] Schilirò T, Tommasi T, Armato C, Hidalgo D, Traversi D, Bocchini S, et al. The study of electrochemically active planktonic microbes in microbial fuel cells in relation to different carbon-based anode materials. Energy. 2016;106:277-84. 12

ACCEPTED MANUSCRIPT

[9] Rahimnejad M, Adhami A, Darvari S, Zirepour A, Oh S-E. Microbial fuel cell as new technology for bioelectricity generation: A review. Alexandria Engineering Journal. 2015;54:745-56. [10] Rahimnejad M, Bakeri G, Najafpour G, Ghasemi M, Oh S-E. A review on the effect of proton exchange membranes in microbial fuel cells. Biofuel Research Journal. 2014;1:715. [11] Ghasemi M, Daud WRW, Ismail M, Rahimnejad M, Ismail AF, Leong JX, et al. Effect of pre-treatment and biofouling of proton exchange membrane on microbial fuel cell performance. International Journal of Hydrogen Energy. 2013;38:5480-4. [12] Bond DR, Lovley DR. Evidence for involvement of an electron shuttle in electricity generation by Geothrix fermentans. Applied and Environmental Microbiology. 2005;71:2186-9. [13] Reguera G, McCarthy KD, Mehta T, Nicoll JS, Tuominen MT, Lovley DR. Extracellular electron transfer via microbial nanowires. Nature. 2005;435:1098-101. [14] Hassan SH, Kim YS, Oh S-E. Power generation from cellulose using mixed and pure cultures of cellulose-degrading bacteria in a microbial fuel cell. Enzyme and Microbial Technology. 2012;51:269-73. [15] Oh S, Logan BE. Hydrogen and electricity production from a food processing wastewater using fermentation and microbial fuel cell technologies. Water Research. 2005;39:4673-82. [16] Rezaei F, Richard TL, Brennan RA, Logan BE. Substrate-enhanced microbial fuel cells for improved remote power generation from sediment-based systems. Environmental Science & Technology. 2007;41:4053-8. [17] Hassan SH, El-Rab SMG, Rahimnejad M, Ghasemi M, Joo J-H, Sik-Ok Y, et al. Electricity generation from rice straw using a microbial fuel cell. International Journal of Hydrogen Energy. 2014;39:9490-6. [18] Esmaeili C, Ghasemi M, Heng LY, Hassan SH, Abdi MM, Daud WRW, et al. Synthesis and application of polypyrrole/carrageenan nano-bio composite as a cathode catalyst in microbial fuel cells. Carbohydrate Polymers. 2014;114:253-9. [19] Ghasemi M, Daud WRW, Hassan SH, Jafary T, Rahimnejad M, Ahmad A, et al. Carbon nanotube/polypyrrole nanocomposite as a novel cathode catalyst and proper alternative for Pt in microbial fuel cell. International Journal of Hydrogen Energy. 2016;41:4872-8. [20] Logan BE, Murano C, Scott K, Gray ND, Head IM. Electricity generation from cysteine in a microbial fuel cell. Water Research. 2005;39:942-52. [21] Logan BE, Regan JM. Microbial Fuel Cell. Environmental Science & Technology. 2006. [22] Liu H, Cheng S, Huang L, Logan BE. Scale-up of membrane-free single-chamber microbial fuel cells. Journal of Power Sources. 2008;179:274-9. [23] Keskin T, Hallenbeck PC. Hydrogen production from sugar industry wastes using single-stage photofermentation. Bioresource Technology. 2012;112:131-6. [24] Liu Y, Xu J, Zhang Y, Yuan Z, He M, Liang C, et al. Sequential bioethanol and biogas production from sugarcane bagasse based on high solids fed-batch SSF. Energy. 2015;90:1199-205.

13

ACCEPTED MANUSCRIPT

[25] Zhang B, Zhao H, Zhou S, Shi C, Wang C, Ni J. A novel UASB–MFC–BAF integrated system for high strength molasses wastewater treatment and bioelectricity generation. Bioresource Technology. 2009;100:5687-93. [26] Wu C-H, Liu S-H, Chu H-L, Li Y-C, Lin C-W. Feasibility study of electricity generation and organics removal for a molasses wastewater by a waterfall-type microbial fuel cell. Journal of the Taiwan Institute of Chemical Engineers. 2017;78:150-6. [27] Flimban SGA, Hassan SHA, Rahman MM, Oh S-E. The effect of Nafion membrane fouling on the power generation of a microbial fuel cell. International Journal of Hydrogen Energy. 2018. [28] Khatiwada D, Venkata BK, Silveira S, Johnson FX. Energy and GHG balances of ethanol production from cane molasses in Indonesia. Applied Energy. 2016;164:756-68. [29] Molino A, Giordano G, Motola V, Fiorenza G, Nanna F, Braccio G. Electricity production by biomass steam gasification using a high efficiency technology and low environmental impact. Fuel. 2013;103:179-92. [30] Song Y, Yang T, Zhou X, Zheng H, Suye S-i. Microsensor for hydroquinone and catechol based on poly (3, 4-ethylenedioxythiophene) modified carbon fiber electrode. Analytical Methods. 2015. [31] Zhou XF, Song YH, He KY, Zheng HT, Suye S. Electrochemical preparation and application of PEDOT/ferrocene modified electrode. Applied Mechanics and Materials: Trans Tech Publ; 2015. p. 61-4. [32] Horwitz W, Chichilo P, Reynolds H. Official methods of analysis of the Association of Official Analytical Chemists. Official methods of analysis of the Association of Official Analytical Chemists. 1970. [33] Atlas RM, Brown AE, Parks LC. Laboratory manual of experimental microbiology: Mosby; 1995. [34] Hassan SH, Van Ginkel SW, Kim S-M, Yoon S-H, Joo J-H, Shin B-S, et al. Isolation and characterization of Acidithiobacillus caldus from a sulfur-oxidizing bacterial biosensor and its role in detection of toxic chemicals. Journal of Microbiological Methods. 2010;82:151-5. [35] APHA. Standard methods for the Examination of water and wastewaters,. American Public Health Association. 20th edition, ed. ed. Washington DC,1998. [36] Huang L, Zeng RJ, Angelidaki I. Electricity production from xylose using a mediatorless microbial fuel cell. Bioresource Technology. 2008;99:4178-84. [37] Zhang Y, Min B, Huang L, Angelidaki I. Generation of electricity and analysis of microbial communities in wheat straw biomass-powered microbial fuel cells. Applied and Environmental Microbiology. 2009;75:3389-95. [38] Kim BH, Park HS, Kim HJ, Kim GT, Chang IS, Lee J, et al. Enrichment of microbial community generating electricity using a fuel-cell-type electrochemical cell. Applied Microbiology and Biotechnology. 2004;63:672-81. [39] Mathuriya AS, Sharma V. Bioelectricity production from various wastewaters through microbial fuel cell technology. Journal of Biochemical Technology. 2010;2:133-7. [40] Li Z, Yao L, Kong L, Liu H. Electricity generation using a baffled microbial fuel cell convenient for stacking. Bioresource Technology. 2008;99:1650-5. [41] Zhi-Dan L, Jing L, Zhu-Wei D, Li H-R. Construction of sugar-based microbial fuel cells by dissimilatory metal reduction bacteria. Chinese Journal of biotechnology. 2006;22:131-7. 14

ACCEPTED MANUSCRIPT

[42] Liu L, Li F-b, Feng C-h, Li X-z. Microbial fuel cell with an azo-dye-feeding cathode. Applied microbiology and biotechnology. 2009;85:175. [43] Zheng X, Nirmalakhandan N. Cattle wastes as substrates for bioelectricity production via microbial fuel cells. Biotechnology Letters. 2010;32:1809-14. [44] Jung S, Regan JM. Comparison of anode bacterial communities and performance in microbial fuel cells with different electron donors. Applied Microbiology and Biotechnology. 2007;77:393-402. [45] Rahimnejad M, Mokhtarian N, Najafpour G, Daud W, Ghoreyshi A. Low voltage power generation in abiofuel cell using anaerobic cultures. World Appl Sci J. 2009;6:15858. [46] Zou Y, Xiang C, Yang L, Sun L-X, Xu F, Cao Z. A mediatorless microbial fuel cell using polypyrrole coated carbon nanotubes composite as anode material. International Journal of Hydrogen Energy. 2008;33:4856-62. [47] Mohan Y, Kumar SMM, Das D. Electricity generation using microbial fuel cells. International Journal of Hydrogen Energy. 2008;33:423-6. [48] Ren Z, Steinberg L, Regan J. Electricity production and microbial biofilm characterization in cellulose-fed microbial fuel cells. Water Science and Technology. 2008;58:617-22.

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Table 1. The physicochemical parameters of sugarcane molasses. Parameters pH

Values 5.1

Total soluble solids%

86.67

Density g / cm3

1.40

Total sugar %

51.36

Non fermentable sugars %

4.66

Fermentable sugars %

46.70

Ash %

10.45

Nitrogen %

0.39

Calcium, CaO %

0.83

Sulfate (as SO4)%

1.47

Sodium %

0.16

Potassium %

3.12

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Table 2. Biochemical characteristics of the strain STRI1. Biochemical test

Result

Gram stain

+

Oxidase

-

L-Arabitol (IARL)

+

D-Cellobiose (dCEL) Beta-Galactosidase (BGAL)

+

H2S Production (H2S)

-

D-Glucose (dGLU)

+

D-Maltose (dMAL)

-

D-Mannitol (dMAN)

+

D-Sorbitol (dSOR)

-

D-Mannose (dMNE) Sucrose (SAC)

+ +

Citrate (Sodium) (CIT) L-Proline Arylamidase (ProA)

+ +

Lipase (LIP) Urease (URE) Lysine Decarboxylase (LDC) Phosphatase (PHOS)

+ + +

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Table 3. Comparison of B. borstelensis STRI1 for power density with other microorganisms and substrates from literature review.

Microorganisms Rhodoferax ferrireducens Klebsiella pneumoniae L17 Nocardiopsis sp. KNU Streptomyces enissocaesilis KNU Escherichia coli strain K-12 Geobacter SPP

Substrate

Type of MFC H-type

Vol (ml)

Catholyte

200

Air cathode

Glucose H-type Glucose CMC CMC Cattle manure Acetate

H-type H-type H-type H-type

75 250 250 NA 250

K3Fe(CN)6 K3Fe(CN)6

10 %Pt (0.35 mg/cm2)

H-type

720

Air

Lactate

H-type

250

10 %Pt (0.35 mg/cm2)

E. coli (DH5α)

Glucose Malt extract

H-type H-type

100 500

K3Fe(CN)6 Air

H-type

310

K3Fe(CN)6

H-type

310

K3Fe(CN)6

H-type

250

K3Fe(CN)6

H-type H-type

200 250

K3Fe(CN)6 K3Fe(CN)6

CMC

Cellulose Wheat straw Mixed culture bacteria Rice straw B. borstelensis STRI1 Molasses

18

158 mA/m2

[41]

34 mW/m2 [42] 162 mW/m2 [14] 145 mW/m2 [14]

Air cathode

Glucose

G. sulfurreducens and C. cellulolyticum G. sulfurreducens and C. cellulolyticum Wastewater

Ref.

Azo dye

Saccharomyces cerevisiae Geobacter spp

Enterobacter cloacae

Power or current density

67 mW/m2 40.3 ± 3.9 mW/m2 16 mW/m2

[43] [44] [45]

52 ± 4.7 [44] mW/m2 228 mW/m2 [46] [47] 2 9.3 mW/m [48] 2 153 mW/m [48] 2 83 mW/m 123 mW/m2 [34] 188 mW/m2 [17] 185.5mW/m2 This study

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Figure 1. Phylogenetic tree based on 16srRNA gene sequence showing the position of strain STRI1 with related taxa.

1200 Second cycle Closed circuit Open circuit

1000

mV

800 600 Second cycle

400 200 0 0

20

40

60

80

100

120

Time (Days)

Fig 2. Generation of electricity by Brevibacillus borstelensis STRI1, at closed and open circuit mode.

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1000

200

Voltage (mV)

800

160 140

600

120 100

400

Voltage Power density

80 60

200

Power density (mW/m2)

180

40 0

20 0.0

0.2

0.4

0.6

0.8

Current (mA)

Fig 3. Voltage(V) and power density (mW/m2) vs current at concentration (1.5 g/L as COD) of sugarcane molasses.

1800

100 COD COD removal %

1600

80

1400

60

1000

%

mg/L

1200

40

800 600

20

400 200

0 0

5

10

15

20

Time (Days)

Figure 4. COD removal as a function of time

25

30

35

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0.0010 Without bacteria With bacteria

0.0008

Currunt (A)

0.0006 0.0004 0.0002 0.0000 -0.0002 -0.0004 -0.0006 -0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

Applied Voltage (V)

Figure 5. Cyclic voltammetry curves of (ο) a used anode without bacteria and (●) anodic biofilm with Brevibacillus borstelensis STRI1during steady state of electricity generation.

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Research highlights



Electricity can be produced from sugarcane as a substrate.



Brevibacillus borstelensis STRI1 could be used as a catalyst in MFC.



The power density increased by increasing sugarcane concentration..



Sugarcane degradation were elucidated through COD removal & electricity generation