alexa Impact of Salt Concentrations on Electricity Generation using Hostel Sludge Based Duel Chambered Microbial Fuel Cell | Open Access Journals
ISSN: 2155-9821
Journal of Bioprocessing & Biotechniques
Like us on:
Make the best use of Scientific Research and information from our 700+ peer reviewed, Open Access Journals that operates with the help of 50,000+ Editorial Board Members and esteemed reviewers and 1000+ Scientific associations in Medical, Clinical, Pharmaceutical, Engineering, Technology and Management Fields.
Meet Inspiring Speakers and Experts at our 3000+ Global Conferenceseries Events with over 600+ Conferences, 1200+ Symposiums and 1200+ Workshops on
Medical, Pharma, Engineering, Science, Technology and Business

Impact of Salt Concentrations on Electricity Generation using Hostel Sludge Based Duel Chambered Microbial Fuel Cell

Anand Parkash*, Shaheen Aziz and Soomro SA
Department of Chemical Engineering, Mehran University of Engineering and Technology, Jamshoro, Pakistan
Corresponding Author : Anand Parkash
Department of Chemical Engineering
Mehran University of Engineering and Technology
Jamshoro, Pakistan
Tel: 0333-796-2266
E-mail:
[email protected]
Received August 18, 2015; Accepted August 24, 2015; Published August 28, 2015
Citation: Parkash A, Aziz S, Soomro SA (2015) Impact of Salt Concentrations on Electricity Generation using Hostel Sludge Based Duel Chambered Microbial Fuel Cell. J Bioprocess Biotech 5:252 doi:10.4172/2155-9821.1000252.
Copyright: © 2015 Parkash A, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Visit for more related articles at Journal of Bioprocessing & Biotechniques

Abstract

Electrical energy needs in Pakistan are expected to continue to rise. The use of petroleum as a source of energy still dominates, although oil reserves in Pakistan are increasingly being depleted. Therefore, there is a need to develop alternative source of sustainable energy, such as Microbial Fuel Cell (MFC). MFC shows another type of renewable energy by changing natural matter into power with the help of microbes. In the present study, varied salt concentrations of a salt bridge in novel MFC design were analyzed. Sewage sludge was utilized, which contains a lot of organic materials and is additionally one of the major sources of ecological contamination, as substrate MFC. Saccharomyces cerverciae sp. (44 g) was used as a biocatalyst. Methylene blue (10 ml) was used as a mediator and potassium ferricyanide (100 ml) was used as an oxidizing agent for the conversion of sewage sludge into voltage generation using lab-scale double chamber MFC. Varied salt concentrations (1M, 3M and 5M of KCl and NaCl) of salt concentrations of salt bridge in a novel MFC design were analyzed. The maximum generated voltage, current, power, power density and current density with 1M KCl were 0.451 V, 0.0451, 0.0175561 mW, 0.000226001 mW/m2, 10.5166661 μA/m2 respectively. The MFC was run for a period of 1 day and readings were noted at regular intervals. The results obtained were helpful in designing an optimized MFC.

Keywords
Salt bridge; Electrical energy; Microbial fuel cell; Sewagesludge
Introduction
Due to continuous depletion of the fossil fuels and constantincrease in the fuel’s price, the world is moving towards the energycatastrophe [1-3]. However, consumption of fossil fuels causes anincrease in pollution level which is a major cause of global warming.So requisition of an alternate source of energy is increasing day byday which should be economical, reusable and clean [4,5]. The MFCsprovide a promising technology to handle the above two problems bydecomposing organic waste to using it [6,7]. For creating a practicalworld, we need to reduce the utilization of fossil fuels furthermorethe pollutants generated. These two points could be accomplishedtogether by treating bio-waste [8,9]. In 1911, MC Potter observed thatbacteria can be used to produce electrical energy. However, insufficientresearch was done to advance this technology during 1911-1967. Butin 1967, John Davis patents the first MFC technology and possibleapplication and research on MFC was begun after 1990’s. Most ofthe patent was issued in 2000’s [9-11]. MFC may be best describedas a bioreactor, where microbes act as biocatalyst in metabolizingthe organic substances containing the organic carbon to generateelectricity [12,13]. Electrons are produced by the oxidation of organicmaterials in which microbes act as catalyst [14,15]. The electrons thusproduced are transferred to a terminal accepter such as O2, nitrate andsulphate. These terminal electron accepters are get reduced by theseelectrons [16,17]. A new product is found which can leave the cellswhen terminal electron acceptors are diffused into the cells. However,there are some microbes specially yeast that can transfer their electronsin the outer space surrounding the cells which are accepted by theawaiting terminal electron acceptors [18,19]. These types of microbesare called exogenic and can be utilized to generate electricity within aMFC. The advantages of MFC are easily available exogenic materialswhich are used as substrate and microbes which act as biocatalyst [20].It is a simple system and unlike the hydrogen fuel cells, a MFC doesnot require extremely synchronized division system. It is more effectivethan enzymatic fuel cell in harvesting electrons from transport systemof microbes [21]. This MFC mainly consists of two chambers, one of the chambers, where, oxidation takes place is call anodic chamber (anode)and the other chamber where reduction takes place is called cathodicchamber (cathode) [12-15]. In the presence of oxygen, microbes oxidizeorganic compounds to produce CO2 and H2O, but if the reaction takesplace in anaerobic environment then microbes decomposes organicmaterials to produce CO2, while proton and electrons are producedsimultaneously [22-24]. Electrons thus produced are transferred to thecathodic chamber via an external circuit while protons are transferredthrough salt bridge [23]. This flow of electrons generates voltages [24].Unique design adjustments utilized these years have given huge yieldsand opened wild in the multidisciplinary MFC research [24,25]. Theaim of this research is to take the inward assents of waste materials, likesewage sludge using double chamber MFC for electricity generationand concentrates on the study including different centralizations ofsalt in salt extension of an arbiter MFC. This paper focuses on the studyinvolving various concentrations of salt in salt bridge of a mediator MFC.
Materials and Methods
Substrate collection-sewage sludge
Sewage sludge (1000 ml), which served as the substrate of the MFCwas collected from the hostel of MUET Jamshoro, Pakistan.
Cathodic and anodic chamber
These chambers of the MFC were made up of plastic bottles.Two plastic bottles each of 1000 ml were used for this purpose. The bottle was washed with distilled water and then medium was filled init. Methylene blue (10 ml), sewage sludge (1000 ml) as a sample and Saccharomyces cervesiae sp. (44 g) added to it.
Salt bridge
Salt bridge employed here was made with 5M NaCl and 10%Agar. The salt bridge was cast in a PVC pipe (12 cm × 2 cm). Properprecautions were taken to ensure complete sealing of anodic chamberby means of applying epoxy and wax to ensure anaerobic conditions.The external circuit was completed by connecting a resistor (10 Ω)between the two leads of the electrodes.
Fabrication and operation of double chamber MFC
Salt Bridge-Immersed-Air Cathode MFC consisted of a plasticcontainer of capacity 2 liters which served as the anodic chamber(Figure 1). The anodic compartment contained the substrate and thecopper electrodes (6″ each). The salt bridge served as an electrolyte intransfer of protons. The cathode was immersed in the salt bridge whenit was in molten stage to ensure complete surface contact. The 50%cathode surface was exposed to atmospheric air.
MFC operation
Substrate (sewage sludge), was added in anaerobic chamber (anodicchamber) and then it is sealed completely for the creation of anaerobicconditions. The MFC was sparged with CO2 before sealing completelyto ensure complete removal of oxygen. A batch configuration wasemployed and readings were taken for a period of 6 days. The readingswere taken on a daily basis.
Optimization of salt in salt bridge
Various strong salts for salt bridge preparation: Two well-knownstrong salts Sodium Chloride (NaCl) and Potassium Chloride (KCl)were tested for efficacy to transport H+ ions in the salt bridge. A dualchambered MFC with sewage sludge as substrate were setup withrespective strong salt used for salt bridge fabrication. The cells were runfor 6 days and readings were noted at regular intervals.
Molar concentration of salt: Salt bridges were prepared withvarious Molar concentrations 1, 3, 5M KCl and NaCl and with agarconcentration of 10%. A dual chambered MFC with sewage sludge assubstrate was setup with above mentioned varying salt concentrationsin salt bridge. The cells were run for 6 days and readings were noted atregular intervals.
Measurement of output: The output of the MFC was expressedby means of voltage (V). For this purpose a digital multimeter wasused and was calibrated each time before use. Resistance of 10 Ω wasemployed in all experiments and hence calculations were based onit. Readings from the multimeter were noted only after a steady andconstant value was obtained. The multimeter was connected in serieswith MFC when measuring voltage.
Results
Effect on voltage generation by variation in salts concentration
A two chamber MFC setup was adopted initially with 1M KClsolution to make the salt bridge. After that it was checked for 1MNaCl. Again KCl and NaCl were used in different concentration suchas 3M and 5M for fabricating salt bridge. After comparing the resultsof difference KCl and NaCl concentrations, it was found that the saltbridge made up of KCl functions better than that of NaCl.
1M KCl and 1M NaCl: In this experiment, 1M KCl and 1M NaCl(Figures 2 and 3) were used to transport H+ ions in the salt bridge.The voltage generation was recorded per twenty minutes through thewhole day for the substrate sewage sludge. The maximum generatedvoltage obtained with 1M KCl and 1M NaCl was 0.451 V and 0.372 V(Tables 1 and 2) respectively. The MFC was run for a period of 1 dayand readings were noted at regular intervals.
3M KCl and 3M NaCl: In the experiment, 3M KCl and 3M NaCl(Figures 4 and 5) were used to transport H+ ions in the salt bridge. Thevoltage generation was recorded per day throughout the week for thesewage sludge. The maximum generated voltage obtained with 3M KCl and 3M NaCl was 387 V and 248 V (Tables 3 and 4) respectively. TheMFC was run for a period of 1 day and readings were noted at regularintervals.
5M KCl and 5M NaCl: In the experiment, 5M KCl and 5M NaCl(Figures 6 and 7) were used to transport H+ ions in the salt bridge.The maximum generated voltage obtained with 5M KCl and 5MNaCl is 356 V and 232 mV (Tables 5 and 6) respectively. The MFCwas run for a period of 7 days and readings were noted at regularintervals
Discussion
The design of a dual chamber MFC is highly critical and needsbest optimization. The Two Chamber MFC used in primitive studieswas replaced by the Salt bridge immersed air cathode MFC. The twochamber system has a disadvantage of increased internal resistance and whereas in the MFC, the internal resistance is significantlylowered. MFC is a novel design that increased the cathode potentialwith increased oxygen availability and enhanced surface area contactwith the salt bridge. Large scale MFCs can basically employ air cathodeMFC as it increases the output and also decreases the task of concernin chamber design, space and thereby cost. As the primary designingapplication for MFC will be electricity generation from sewage sludge,reduce the concern over the design, will be vital for the operation ofMFC. The main challenge in improving voltage generation is to makeframework plans that diminish resistance. The study involved SaltBridge which is the most economical component in the dual chamberMFC. For the first part of the study, KCl and NaCl were comparedfor use as strong salt in salt bridge. The study clearly showed thatthere was not much difference between these salts in terms of voltageoutput. Molar concentration of salt is critical since the transfer ofprotons through the salt bridge is facilitated by the dissociated ions init. The experiments showed that, with increase in molar concentrationthe current decreases. Optimum results were obtained for salt bridgefabricated using 1M NaCl. It produced a maximum voltage of 0.372V. The membrane based MFC needs membrane replacement due tofouling which decreases the lifetime of its use in MFC. The salt bridgeMFC also needs to be studied extensively, as the literature availableon salt bridge based MFC is not sufficient. However, the magnitudeof electron transfer should be higher and earlier than the respiratory chain. Identifying a potential substrate that is enormously available,low cost, high energy yields and renewable for alternate energyproduction is imperative. Wastes with high organic content are a good candidature of choice in MFC as a substrate. Highly homogenizedsubstrate and availability for microbial consortium can be attributed tothe maximum current obtained.
Conclusion
The study involved double chambered MFC using Salt Bridgewhich is the most economical component in the MFC. For the firstpart of the study, KCl and NaCl were compared for use as strong salt insalt bridge. Molar concentration of salt is critical since the transfer ofprotons through the salt bridge is facilitated by the dissociated ions init. The experiments showed that, with increase in molar concentrationthe current decreases. Optimum results were obtained for salt bridgefabricated using 1M KCl and NaCl. It produced a maximum voltage0.451 V and 0.372 V respectively. In this double chamber MFC usingSaccharomyces cerevisiae was used as biocatalyst. Anode chamberwas kept up in batch mode and another side cathode chamber wasmaintained at continuous mode. Our results have indicated that thesalt bridge based MFC needs membrane replacement due to foulingwhich decreases the lifetime of its use in MFC. The salt bridge MFC alsoneeds to be studied extensively, as the literature available on salt bridgebased MFC is not sufficient.
Acknowledgements
The authors wish to express their sincere thanks for the lab facilities providedfor this work in the Department of Chemical Engineering, Mehran University ofEngineering and Technology, Jamshoro, Pakistan.
References

Tables and Figures at a glance

 

Table icon Table icon Table icon
Table 1 Table 2 Table 3
Table icon Table icon Table icon
Table 4 Table 5 Table 6

 

Figures at a glance

 

Figure Figure Figure Figure
Figure 1 Figure 2 Figure 3 Figure 4
Figure Figure Figure
Figure 5 Figure 6 Figure 7
Select your language of interest to view the total content in your interested language
Post your comment

Share This Article

Relevant Topics

Recommended Conferences

  • 17th Euro Biotechnology Congress
    September 25-27, 2017 Berlin, Germany
  • 2nd World Biotechnology Congress
    December 04-06, 2017 Sao Paulo, Brazil

Article Usage

  • Total views: 11704
  • [From(publication date):
    August-2015 - Aug 22, 2017]
  • Breakdown by view type
  • HTML page views : 7920
  • PDF downloads :3784
 

Post your comment

captcha   Reload  Can't read the image? click here to refresh

Peer Reviewed Journals
 
Make the best use of Scientific Research and information from our 700 + peer reviewed, Open Access Journals
International Conferences 2017-18
 
Meet Inspiring Speakers and Experts at our 3000+ Global Annual Meetings

Contact Us

 
© 2008-2017 OMICS International - Open Access Publisher. Best viewed in Mozilla Firefox | Google Chrome | Above IE 7.0 version
adwords