الفهرس 
Introduction and Historical ReviewOnly 14 pages are availabe for public view
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Abstract
Microbial Fuel Cell (MFC) is an eco-friendly renewable energy source that can generate electricity by harvesting electrons gained from a metabolized process inside microorganisms (bacteria). Still now, the use of a single MFC is limited in practical life applications, due to its low power density and output voltage. Accordingly, extensive studies were conducted concerning a set of experimental trails to improve the value of the generated electrical voltage and to achieve benefit from it. In this respect, the aim of the present thesis is to shed further light on performance improvement of the electricity generation from MFC through two main parts, as follows:
Part 1: Electricity Generation from MFC including:
(i) Design and electrolytic analysis of MFC
(ii) Factors affecting MFC performance
Part 2: Energy Harvesting System for Enhancing MFC Generated Electricity
(i) Construction of a stacked series 6- MFCs
(ii) Storing the generated electricity from the stacked series 6-MFCs
(iii) Design and implementation of DC-DC boost / SEPIC converter circuit
(iv) Energy harvesting system operation
Part 1
• Electricity Generation from MFC
First : Design and electrolytic analysis of MFC
1- By using two identical plastic containers (chambers) each of 750 mL working volume capacity (anode and cathode) connected by a tube which is an agar salt bridge that transports protons from the anode chamber (A) to the cathode chamber (K). The salt bridge consists of a cylindrical tube with a diameter of 2.5 cm and a length of 10 cm made of PVC filled with a mixture of agar salt - 10% and sodium chloride (NaCl) to achieve uniformity in the work.
2- To generate electricity from microbial fuel cell, the cathode chamber is fed with an electrolyte solution with a pH ranging from 5 to 7. While, the anode chamber is fed with an electrolyte solution containing biological waste collected from several different sources with different bacterial content. where the main reaction is to generate electricity from biological wastes through microorganisms.
3- Testing the the microbial fuel cell and determining the value of the maximum cell working voltage(Vmax), by :
i- Feeding the anode chamber with two different groups of electrolytes (drinking water and bio-waste water). The first group is identified as a low count of bacteria source (LCB), while the second group as a richied source of bacteria / high count of bacteria (HCB). The groups are classified as follows:
• A low count of bacteria groups (LCB): contain several drinking water samples from different sources (tap; control, and well water; S1, S2, and S3).
• A richied source of bacteria / high count of bacteria groups (HCB): The wastewater is collected from irrigation farmland.
ii- These groups are subjected to different measurements microbiological, chemical, and physical in order to find the factors which are affecting the efficiency of microbial cell operation and to determine the value of its highest output voltage.
a- Microbiological measurements: Included the total content of bacteria (Total Count – T.C) for the used samples especially the total content of anaerobic bacteria (Anaerobic Plate Count, APC) which is considered as a main source of electrical potential in microbial fuel cells. These measurements are carried out at Agricultural Research Center, Central Laboratory of Residue Analysis of Pesticides and Heavy Metal in Food.
b- Chemical measurements: Included measuring the percentages of dissolved minerals and ions present in the used samples. These measurements are carried out at Agricultural Research Center, Soil, Water and Environment Research Institute.
c- Physical measurements: Include the electrical conductivity (σ) and pH value of the used samples.
The obtained results showed that the heighest MFC output voltage (0.49V) is achived from LCB group (Tap water-control), while HCB group, it reached the value of (1.04V). The difference in output voltage which achieved by HCB is related to increasing in anarobic bacteria content (103 fold ), minerals and disolved ions content (> 4 fold) in respect to LCB. The comparision between LCB and HCB groups emphasizes on the real MFC output voltage related to minerals and dissolved ions contributions, besides the microorganism contributions. Also, the work is extended to study the polarization curve of the desinged cells to ensure the efficiency of the electrical performance of the microbial fuel cells.
Second: Factors affecting MFC performance
During the study, the factors affecting the microbial fuel cell electricity generation is introduced as follow as:
1. Choosing the type of materials used in the manufacture of the anode (A) and cathode (k)
These materials are chosen based on a number of factors and properties: environmentally friendly, electrical conductivity (σ), corrosion resistance, the suitability of its surface for bacteria growth (anode) in addition to cost and availability. Aluminum (Al) and copper (Cu) are chosen as suitable materials for the manufacture of both the anode and the cathode, respectively. Aluminum metal is suitable for the assembly and growth of bacteria and has a good electrical conductivity (3 X 107 S / m), while copper comes with a higher electrical conductivity than aluminum (98.5 X 107 S / m), so it becomes the most suitable as a receiving material for electrons generated in the anode chamber.
2. The effect of anode cross sectional area on output voltage
The anode is important for the generation of electricity, as its surface is the environment in which bacteria grow, which generate electrons and then are transmitted to the cathode. In this study, considering the anode electrode cross sectional area, where three separate identical dual chamber MFC reactors (A, B and C) are constructed in the laboratory scale with anode cross sectional areas of 19.25cm2, 38.5cm2 and 55cm2, respectively, and the cell working voltage was monitored for continuous 1400 hours. During the work, the polarization curve and the cell internal resistance are measured at three different periods of the running time (start, middle, and end). The obtained MFC output working voltage and maximum output power are found to increase from (0.68V- 316.52 mW) to (1.04 V- 607.76 mW) with increasing the anode cross sectional area from19.25 cm2 up-to 38.5 cm2. While at area 55 cm2 the values decreased to (0.55 V, 18.04 mW) .
3. The effect of salt bridge concentration
Refering to salt bridge concentration, where various salt concentrations (0.5 M, 1M, 2M, 3M and 4 M) of NaCl are used in the design of the laboratory scale MFC at anode cross sectional area of 38.5 cm2. The MFC is operated and the produced cell working voltage is monitored for continuous 1400 hours of running time and the polarization curve is measured and plotted at three different periods of runing time (start, middle, and end), in addition to measuring the cells internal resistances. At salt bridge concentration of 1M, the MFCs produced maximum output working parameters; voltage (1.047V), and power (607.76 mW). Also, it is observed that when using concentrations higher or less than 1 molar, the output voltage begin to decrease. The obtained results are helpful in designing an optimized MFC.
4. The effect of the nature of bio-waste
Considering the nature of bio-waste, where three different bio-waste samples namely; dairy industry waste water and two different cattle manures (cow dung and buffalo dung) with various concentrations of cattle manures (75%, 50% and 25%). The MFC is operated and the produced cell working voltage is monitored for continuous 720 hours of running time and the polarization curve is measured at three different periods of the running time (start, middle, and end), in addition to measuring the cells internal resistances. The MFCs produced maximum output working parameters; voltage (0.92V), power (93 mW) from 50 % buffalo dung concentration.
Part 2
• Energy Harvesting System for Enhancing MFC Generated Electricity
First: Construction of a stacked series 6- MFCs
Owing to the low MFC generated output voltage, a similar stacked series 6- MFCs are constructed for increasing its generated output voltage (on average 1.04V), where their produced output voltage reached about 6.24 V. At the same time, the polarization curve of the stacked system is studied and Pmax and ri of the system are measured.
Second: Storing the generated electricity from the stacked series 6-MFCs
In order to benefit later from the electricity generated from the stacked MFCs, a 6V/2A lead acid battery is used for storing the output voltage.
Third: Design and implementation of DC-DC boost / SEPIC converter circuit
In this part, the DC-DC converter circuits are designed and tested ,as well the influence of the following electrical parameters; switching frequency, switching duty cycle and the DC input voltage on the converter output voltage are studied for both modes of operation (continous conduction mode, CCM and discontinous conduction mode, DCM).
Fourth: Energy harvesting system operation
During the energy harvesting system operation, the designed converters are operated in the discontinuous conduction mode at load resistance (RL) of 220 Ω up to 5.5 kΩ with an input voltage of 6 V based on the voltage harvested from the stacked series 6- MFCs using 6V/2A lead acid storage battery.
The final output voltage values generated from the system are observed to be ranging from 15.8 V at load resistance of 220 Ω up-to 21.2 V at 620 Ω for DC-DC boost converter. While, applying DC-DC SEPIC, the output voltage ranging from 19.8 V at load resistance of 220 Ω up-to 25.1 V at 620 Ω. Applying, load resistance values up to 5.5 kΩ, the system output voltage based on any of converter circuit is shown to be decreased.