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Chapter 1

INTRODUCTION

Ever since man started to live in communities, we have been throwing things away.

-William Rathje

Production of solid waste is inevitable. A report released by the World Bank (WB) in

2011 states that municipal solid waste that will be generated by Philippine cities will go up

by 165 percent to 77,776 tons per day from 29,315 tons as a consequence of a projected 47.3-

percent hike in urban population by 2025. As we are constantly growing in number, the

allotted land areas as reservoirs for our waste generation are diminishing. Some of them, such

as the case of Irisan dumpsite, have even reached their limits. This results to a scenario where

solid waste in landfills stays longer and becomes more concentrated leading to aggravated

environmental problems that require immediate action.

In the recently concluded National Solid Waste Management Commission (NSWMC)

policy forum for the amendment of the Ecological Solid Waste Management Act of 2000

(RA 9003) and its Implementing Rules and Regulations last September 23 and 24, 2014, a

major concern on landfill leachate treatment was raised due to the lack of attention given to

the topic despite its adverse effects to the ecosystem. Contamination of groundwater,

emission of methane gas to the atmosphere, and the proliferation of disease-bearing animals

and microorganisms all these to name a few.

By definition, landfill leachate is the liquid that drains or leaches from a landfill. It

varies widely in composition considering the age of the landfill and the type of waste that it

contains. It usually includes both dissolved and suspended material. In a landfill that receives

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a mixture of municipal, commercial, and mixed industrial waste, but excludes significant

amounts of concentrated specific chemical waste, landfill leachate may be characterized as a

water-based solution of four groups of contaminants: (1) dissolved organic matter, (2)

inorganic macro components, (3) heavy metals (Pb, Cd, Cu, Hg), and (4) xenobiotic organic

compounds such as halogenated organics (Kjeldsen et al., 2002).

Currently, landfill leachate treatment can be one or a combination of biological,

chemical, and physical processes. Biological treatment removes organics and nitrogen

through processes such as activated sludge, trickling filters, and nitrification or

denifrification. Chemical processes are used to control pH, precipitate metals, and remove

some organics by oxidation. Suspended matter can be removed by the physical processes of

sedimentation and filtration (Tchobanoglous, et.al., 1993). These treatment technologies can

be used to treat leachate for discharge into surface waters, or as pre-treatment prior to

transport to a municipal wastewater treatment facility for further treatment. All of these

management options for leachate treatment require energy input and will increase the landfill

operation and maintenance cost with no additional benefit.

There is substantial energy in leachate that is currently wasted or lost in treatment

processes and these come from waste organic matter and revolutionalize landfill leachate

treatment. One of the most potentially interesting technologies for the production of electrical

energy from organic matters is use the use of Microbial Fuel Cell or MFC a device that

converts chemical energy to electrical energy by the catalytic reaction of microorganisms

(Divetiya, 2014). Capturing this energy would provide a new source of electrical power.

Application of MFC technology for waste treatment was first suggested by early

researchers and was demonstrated for food processing wastewater in 1983. The range of

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organic compounds that can be metabolized by chemotropic microorganisms (and their

enzymes) is extremely large so almost any waste stream may be utilized in an MFC (Caye et.

al., 2008). Among the possible sources of potential bacteria for an MFC is a landfill leachate

due to its microorganism diversity. Currently, the most studied exoelectrogens belong to the

-, -, -, and -proteobacteria (e.g., Geobactersulfurreducens, Geobactermetallireducens,

She- wanellaoneidensis, Escherichia coli, Rhodopseu- domonaspalustris) (Bond and Lovley,

2003; Min et al., 2005a; Ringeisen et al., 2006; Qiao et al., 2008; Xing et al., 2008); while

some non- proteobacteria (e.g., Geothrixfermentans (Bond and Lovley, 2005) and yeasts

(e.g., Saccharomyces cerevisiae (Walker and Walker, 2006)) are also capable of exocellular

electron transfer.

In an MFC, the oxidation of an electron donor compound is physically separated from

the terminal electron acceptor. When microorganisms consume a substance under aerobic

conditions, they produce carbon dioxide and water. However, when oxygen is not present,

they produce carbon dioxide, protons, and electrons. The electrons pass from one part of the

cell called the anode through a circuit that includes an external resistance load, then to a

cathode and finally to the terminal electron acceptor contained in the cathode chamber.

Typically, the anode compartment is separated from the cathode compartment by a proton

exchange membrane (PEM) or cation exchange membrane (CEM). Hydrogen ions pass from

the anode compartment through the membrane to the cathode compartment and combine with

oxygen to form water. By diverting electron flow from microbial respiration to the

electrodes, MFCs convert chemical energy to electrical energy commonly referred to as

bioelectricity generation.

An understanding of the basic interactions inside the MFC as they affect

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characteristics of the substrate is essential. These interactions can explain how the system

functions as a treatment process. Since reduction-oxidation reactions occur when bacteria

consume the organic compounds in a Microbial Fuel Cell, reduction in physico-chemical

parameter concentrations such as biochemical oxygen demand (BOD) and chemical oxygen

demand (COD) are critical to be measured. The effectiveness of mitigating heavy metal

concentration is also observed. Recording pH is also necessary.

Though leachate composition may vary widely, three types of leachates can be

defined according to landfill age (Baig et al.).

Table No. 1 Leachate Classification

Leachate type Young Intermediate Stabilised

Landfill age year 10

pH 7.5

COD g/l >20 3-15 0.3 0.1-0.3

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completely oxidized. The power output from an MFC is directly related to the electrons

captured from the substrate (Caye et al., 2008).

THEORETICAL AND CONCEPTUAL FRAMEWORK

This is an experimental research which investigates the application of Microbial Fuel

Cell in bioelectricity generation and the treatment of landfill leachate from Urdaneta City,

Pangasinan.

A microbial fuel cell is a bioreactor that converts chemical energy in organic

compounds (wastewater) to electrical energy. In an MFC, microorganisms oxidize organic

matter to generate electrons and protons. The electrons are transferred through various

methods to the anode (as an electron acceptor). These electrons are then conducted over a

resistor to the aerobic cathode where oxygen is reduced and meets with protons to produce

water molecules. Microorganisms carry out the conversion under anaerobic conditions

(Ganesh, 2012).

The overall reaction is the breakdown of the substrate to carbon dioxide and water

with a simultaneous production of electricity as a by-product.

In this experiment, a laboratory scale mediator less two chamber cell is used. The

system is composed of an anode and cathode chamber separated by a membrane permeable

to protons. The anode compartment is the anaerobic region where anaerobic bacteria are

located, while the cathode compartment is aerobic. The membrane separation helps to

maintain these conditions for each compartment, yet allows a charge transfer between the

electrodes. Electrodes are placed in each chamber to facilitate the electron transfer process.

Electrons and protons are produced through the oxidation of organic matter. The electrons are

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transferred from the anode electrode, in the anode compartment, and travel through a wire

and resistor to the cathode electrode. Here, the electrons join with the protons which have

diffused through the membrane from the anode compartment, and oxygen to form water. A

catholyte solution must be used to facilitate this reaction.

One part of the fuel cell is the anode. Often, the anode is composed of graphite,

carbon paper or carbon cloth (Clauwaert et. al., 2007). The anodic chamber is filled with the

carbon substrate that the microbes metabolize to grow and produce energy. In this study,

leachate was used as the anode because of its microbial diversity.

Another component of MFC is the cathode. It completes the circuit of the cell by

transferring electrons to a high-potential electron acceptor. The cathode chamber is

commonly filled with a conductive media to facilitate oxygen reduction reaction. Thus, brine

solution was used in this study since it is safe, cheap and readily available. To complete the

cathode chamber, an oxidizing reagent needs to be introduced to maintain the abiotic

environment. Oxygen is the preferred oxidizing agent since it simplifies the operation of the

cell. It is supplied with the aid of an aeration pump that lets the air flow passively inside the

cathode chamber.

To determine the effectiveness of the microbial fuel cell, the power produced was

determined. The voltage of the cell and the resistance of the resistor were measured. With

these, the power generated was computed using the formula Power = (Voltage)2/(Resistance).

Leachates are known for its microbial diversity. It has bacteria, which includes

aerobic, coliform and fecal coliform, psychrophilic and mesophilic bacteria, and spore-

forming bacteria (Matejczyk, et.al, 2011). Microorganisms, such as bacteria, are responsible

for decomposing organic waste. When organic matter such as dead plants, leaves, grass

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clippings, manure, sewage, or even food waste is present in a water supply, the bacteria will

begin the process of breaking down this waste. If there is a large quantity of organic waste in

the water supply, there will also be a lot of bacteria present working to decompose this waste.

In this case, the demand for oxygen will be high so the BOD level will be high. As the waste

is consumed or dispersed through the water, BOD levels will begin to decline. The 5-Day

BOD test was used which involves the dilution of the samples to a volume of 300mL in a

stoppered bottle. The dissolved oxygen of the diluted samples was measured before and after

incubation of five days.

Chemical Oxygen Demand represents the number of electrons contained in a

compound, expressed as the amount of oxygen required to accept the electrons as the

compound is completely oxidized. A chemical oxidation reduction involves the breaking of

chemical bonds and the removal of electrons. The electrons are transferred from the

contaminant to the oxidant. The contaminant is in turn oxidized and the oxidant, the electron

acceptor, is reduced. In this study, initial and final COD concentrations were measured using

HACH colorimeter.

To survive under metal-stressed conditions, bacteria have evolved several types of

mechanisms to tolerate the uptake of heavy metal ions. These mechanisms include the efflux

of metal ions outside the cell, accumulation and complexation of the metal ions inside the

cell, and reduction of the heavy metal ions to a less toxic state. The complex structure of

microorganisms implies that there are many ways for the metal to be taken up by the

microbial cell. The biosorption mechanisms are various and are not fully understood. They

may be classified according to the dependence on the cell's metabolism, which are

metabolism dependent and non metabolism dependent. Also, they may be classified

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according to the location where the metal removed from solution is found: extra cellular

accumulation/precipitation, cell surface sorption/precipitation; and intracellular

accumulation. To test the ability of microorganisms to reduce heavy metal concentration of

the leachate sample, the initial and final concentrations of heavy metals were measured using

Atomic Absorption Spectroscopy (AAS).\

PROBLEM STATEMENT AND HYPOTHESES

To serve as a guide in achieving the objectives of this research, the following

questions are formulated and must be answered at the end of this work:

01. What is the percent reduction of BOD, COD, Pb, Cu, Cd after the treatment?

a. Microbial Fuel Cell

b. Via Precipitation

02. Is there a significant difference in the characteristics (BOD, COD, Pb, Cu, Cd) of

landfill leachate after the treatment between the MFC and via precipitation?

Hypothesis: There is a significant reduction of BOD, COD and heavy metal

concentration before and after the leachate treatment.

03. Is there a significant difference in Chemical Oxygen Demand reduction with

the following variation in load resistance in the Microbial Fuel Cell: 50,

100, and 150?

Hypothesis: There is a significant difference in the Chemical Oxygen

Reduction with varying load resistance (50, 100, and 150) in the

Microbial Fuel Cell.

04. What is the trend of Bioelectricity produced with respect to time?

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I N P U T

O U T P U

T

P R O C E S

S

Raw Material:

- Landfill Leachate

- Brine Solution

Salt Bridge

- Agar

- Sodium Chloride

Fuel Cell

- PET bottle

- PVC pipe

- Copper wire

- Carbon brush

- Collection of Landfill Leachate

- Formulation of Agar for Salt Bridge

- Assembly of Fuel Cell

- Determination of initial and final

BOD, COD and heavy metal

concentration

Microbial Fuel Cell

Figure No. 1 Paradigm of the Study

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SIGNIFICANCE OF THE STUDY

This research aims to establish that MFC is an effective treatment of landfill leachate

and a sustainable energy source. With the current issues pertaining to solid waste

management and the incessant quest for alternative renewable energy sources, the greatest

significance of this work is that it introduces an integrated function of Microbial Fuel Cell as

a landfill leachate treatment system associated with bioelectricity generation utilizing a

sample from the Engineered Sanitary Landfill of Urdaneta City, Pangasinan which currently

caters the garbage of nearby areas in Northern Luzon that includes Baguio City (Camilo and

PEZA), Bautista, Mangatarem, Mapandan, Pozzorubio, Sual and the city of Urdaneta itself.

SCOPE AND DELIMITATION

This study covers the analysis of the landfill leachate characteristics such as BOD,

COD and Heavy Metal concentration utilizing a sample from the Engineered Sanitary

Landfill of Urdaneta City, Pangasinan. The study does not include outside inoculation of

bacteria due to the presence of mixed bacterial community in the leachate. The heavy metal

concentration reduction is limited to lead (Pb), cadmium (Cd), and copper (Cu). For the

cathode compartment and PEM, the salt concentrations are based from related literatures.

For each problem and parameter being investigated on this study, three trials were

conducted since it is the lowest number of trials that is allowed for experimentation. The

observation of the performance of the MFC is limited to every six-hour reading for five days

under room temperature.

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CHAPTER 2

RESEARCH DESIGN AND METHODOLOGY

Research Design and Methodology

This research study adopted the experimental research design that would add

foundation for similar undertakings in the future. The design approach was employed for it

is known to be the most reliable, intellectual and accurate approach. Experimental research

involves the control or manipulation of conditions for the purpose of discovering the

influence of one or more factors upon a condition. The study would demonstrate the viability

of constructing an inexpensive microbial fuel cell as a leachate treatment other than the

conventional methods and toproduce electricity from raw material other than the

conventional sources.

The researchers conducted this experiment to establish the extent of the leachate

treatment andits potential as a renewable source of energy through a microbial fuel cell. The

researchers gathered leachate from the Engineered Sanitary Landfill of Urdaneta City,

Pangasinan. Samples were immediately brought to the Environmental Research Laboratory

and conducted the necessary test to determine its physico-chemical properties. Leachate

samples were then transferred to its respective compartments in the fuel cell and the

generated electricity in terms of volts measured every 6 hours for 5 days.

Data Gathering Tools

For gathering data, the researchers performed an experiment utilizing the different

resources found in the Environmental Research Laboratory (ERL) of Saint Louis University.

The researchers also supplemented the data with information from scholar articles in the

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internet, related literature and research materials about Microbial Fuel Cell (MFC) and

related books about leachate treatment process.

To support the validity of the research, the researchers performed an experiment

using several trials in varying the resistance used for each sample. Statistical methods, such

as T-test, Analysis of Variance (ANOVA) were also used to analyse the collected data.

Data Gathering Procedure

A. Collection of Raw Materials

The leachate sample was obtained from the Engineered Sanitary Landfill of Urdaneta

City, Pangasinan. The sample was put into a cooler to ensure freshness. It was then

transported to the laboratory for immediate tests.

B. Leachate characterization

Leachate characterization was conducted before and after the leachate treatment

process in Microbial Fuel Cell. Analyses for pH, Biochemical Oxygen Demand (BOD) and

Chemical Oxygen Demand (COD) were conducted at Environmental Research Laboratory

(ERL) of Saint Louis University. Meanwhile, AAS for heavy metals were conducted at

Philex Mines.

1. Biochemical Oxygen Demand (BOD) Measurement

10 mL of pure leachate sample was transferred in an empty BOD bottle. The BOD

bottle was filled with distilled water up until the opening of the bottle and was immediately

covered with glass stopper. The bottle was inverted 10 times to mix the leachate sample and

the distilled water. The stopper was removed and 6 mL of the mixture was discarded. 2 mL

of alkaline iodide solution and 2 mL of manganous sulphate solution were added. The bottle

was then covered with the stopper, inverted 20-30 times and flocs were allowed to settle. 2

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mL of concentrated sulphuric acid was added, and the bottle was then inverted 20-30 times to

allow mixing. 203 mL of the solution was measured and transferred to a 250 mL Erlenmeyer

flask. The solution was titrated using sodium thiosulphate as the titrant until the color of the

solution turns to pale yellow. Enough amount of starch solution was added such that the

color of the solution turned to blue. Titration was continued until the solution became

colorless. Afterwards, the volume of the sodium thiosulphate consumed was recorded. This

served as the initial dissolved oxygen in mg/L.

10 mL of the leachate sample was transferred to an empty BOD. The BOD bottle was

filled with dilution water up until the near opening of the bottle, and was then covered with

glass stopper. The bottle was covered with cap to ensure that there was no air entering. The

bottle was stored in an incubator at 20 C and analyzed after 5 days.

2. Chemical Oxygen Demand (COD) Measurement

10 mL of the leachate sample was transferred in a beaker and was diluted with 100 mL

distilled water. Afterwards, 2 mL of the diluted solution was transferred in the COD vial and

inverted gently several times to allow mixing. The vials were placed in the COD digester

and heated to 150 C for 2 hours. The vials were then allowed to cool to 120 C or less and

the chemical oxygen demand was measured using HACH colorimeter.

3. Heavy Metal Measurement

Leachate samples were digested as follows: 50 mL of well-mixed sample was transferred

to a 250 mL beaker and heated using a hot plate with a temperature of 200-300 until the

volume was reduced to 15 20 mL. Concentrated nitric acid (15 mL) was added and the

sample was heated for 30 minutes. Afterwards, 15 mL of concentrated hydrochloric acid was

added and the sample was further heated for 30 minutes. The solution was then allowed to

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cool in a water bath for 15-20 minutes. The digested sample was then transferred

quantitatively with deionized water to a 100 mL volumetric flask and diluted to volume.

After the digestion, samples were brought to Philex Mines for analysis using Atomic

Absorption Spectroscopy (AAS).

C. Microbial Fuel Cell Construction

1. Construction of Anode and Cathode Compartments

Gatorade bottles (500 ml) were collected and used as anode and cathode compartments.

Circular holes were made into the bottom half of the Gatorade bottles about 2 inches in

diameter using a heated red hot tansan (crown). Sandpaper was used to smoothen the edges

of the holes made. These bottles were washed with mild soap and water.

2. Preparation of Electrode

For every cell, two copper wires were cut into 6-inches long. Each of the copper

wires was soldered into carbon brushes (SM-56). The cover of the Gatorade bottle was

drilled to make a hole to which the sponge and the copper wire with the carbon brush was

inserted for the anode compartment. For the cathode compartment, a tiny hole in the center

of the sponge was used to hold the copper wire so it freely hung to the saltwater solution.

3. Preparation of Proton Exchange Membrane (Salt bridge)

Moldex PVC pipes were used to hold the salt bridge. The pipes were cut into 5

inches long using saw. 3 pipes were cut for the fuel cells.

In preparation of the agar solution, 500 ml of distilled water was heated in a beaker

using a beaker using a Bunsen burner. Twenty grams of laboratory grade Agar-Agar powder

was put into the beaker then stirred. When the solution started to boil, 10 grams of salt was

added to the mixture. The solution was stirred continuously until it became viscous. The

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pipes were placed in another 1000 ml beaker. The solution of salt and agar was then poured

into this beaker filling up the pipes. These were cooled to room temperature until the agar-

agar hardened.

4. Preparation of Saltwater Solution

125 grams of Sodium Chloride (NaCl) crystals was weighed using a digital balance

then dissolved into 1 liter of distilled water until a solution was formed. The solution was

transferred into a plastic bottle. For a set-up of 3 cells, one liter of salt solution was needed

5. Fuel Cell Assembly

After the preparation of the materials, the fuel cell was assembled. The salt bridge

was inserted to the holes of the Gatorade bottles, connecting the two compartments. A glue

gun was used to cover the spaces of the salt bridge and the hole to ensure no leakage to

occur. The anode compartment was for the leachate. Meanwhile, the cathode was for the

salt solution. The electrodes were inserted after placing the bacteria and the salt solution.

D. Testing the Potential of Leachate to Generate Power

Considering three trials consisting of three sample set-ups, 225 ml of leachate was

used for this experiment. The leachate was allowed to have contact with the salt bridge and

the electrode. 225 mL of salt solution was then poured into each of the cathode compartment

of each MFC. This amount was just enough to fill half of the bottle. The electrode was then

fully immersed into the salt solution.

After this, a multitester was used to measure and monitor the voltage and current

produced of each MFC in 6-hour intervals for five days. These data were then recorded.

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Treatment of Data

After the experimentation , the data will be subjected to computational and statistical

analysis.

The amounts of reduction for different parameters (BOD, COD, Pb, Cu, Cd) will be

expressed in terms of percentages.

% =

100 ( Equation 2.1)

To determine the significant difference in BOD, COD, pH, Pb, Cd, Cu between the

control and the Microbial Fuel Cell, the results will be statistically treated using T-test. The

equation given will be used to determine the difference needed for viability of treatment.

(Equation 2.2)

A line graph will be used to establish the relationship and identify the trend between

the amount of power produced with time. The time will be the abscissa while power will be

the ordinate of the graph.

In the determination of the existence of a significant difference in the COD reduction

of the varied resistance of the Microbial Fuel Cell, the results are statistically treated using

One-way Analysis of Variance (ANOVA) and Tukeys Honest Significant Difference (HSD)

Test.

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The F-Test through the One-Way Analysis of Variance (ANOVA) is used to

determine the significance of the differences among the COD reduction obtained using varied

resistance of Microbial Fuel Cell. The formulas utilized are given by the one-way ANOVA

table below:

Table 2-1

One-way ANOVA Table

SOURCE OF

VARIATION

DEGREES OF

FREEDOM

SUM OF

SQUARES

MEAN

SQUARE

F

Between Groups k-1 SSC S12=SSC/k-1

Within Groups N-k SSE S22=SSE/k-1

Total N-1 SST

SST =

SSC=

SSE=SST-SSC

Where:

k= no.of treatment

N=total sample in the whole treatment

n=total sample per treatment

S12

S22

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SS=sum of squared deviations

F=degrees of freedom

X=sample being analysed

The Tukeys Honest Significant Difference (HSD) Test was used to determine the

best resistance for COD reduction in Microbial Fuel Cell. The test statistic was computed the

following formula:

=

Where:

Q= value from THSD table

MSwithin= Mean Square within Groups from ANOVA Table

n= number of trials per treatment

To resolve the problems of the study, the researchers carefully and systematically

presented the data in tables which are supported by computations. Descriptions and

interpretations. It was through these means that the researchers were able to come up with

analyses and interpretations showing the relationship of the findings to the problem.

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