Are microbial fuel cells the future of wastewater treatment and Environmental Protection?
Microbial fuel cells show the potential for a sustainable route to mitigate the growing energy demands for wastewater treatment and environmental protection. The indigenous exoelectrogenic microbial communities in the MFCs are capable of degrading various forms of wastewaters.
How does a microbial fuel cell work?
Diagram of a microbial fuel cell that uses a proton-exchange membrane to allow hydrogen ions to pass between the anode and cathode side of the cell. Incoming waste water brings bacteria which attach to an anode and produce electrons and hydrogen ions. The electrons travel up the anode to an external circuit and flow back down into the cathode.
Can a mud sample be used to build a microbial fuel cell?
The goal is to build a microbial fuel cell using a benthic mud sample from a stream and determine if this device can harvest the electrons that the anaerobic bacteria (present in the mud sample) create. In order to reduce pollution, we need to develop alternative and renewable energy sources.
What is a mudwatt microbial fuel cell?
The MudWatt microbial fuel cell (affectionately dubbed the "Dirt Battery") is a device that uses bacteria to convert the organic matter found in mud into electricity. This Instructable will walk you through making your own microbial fuel cell using any MudWatt Science Kit. Any container (if you're using a different vessel)
How do you make a microbial fuel cell at home?
How to make your own microbial fuel cellMaterials.Get drilling. Drill a hole for the copper wire in the lid of each container. ... Coil the graphite. Strip the ends of two pieces of copper wire and wrap one around each pencil lead. ... Mix the solution. ... Squeeze the oxygen. ... Feed the microbes.
How do you make a homemade fuel cell?
0:261:54How to Build a Hydrogen Fuel Cell - YouTubeYouTubeStart of suggested clipEnd of suggested clipStep 1 cut the wire into two six inch pieces wound. Each piece tightly around a nail to form coilsMoreStep 1 cut the wire into two six inch pieces wound. Each piece tightly around a nail to form coils that will serve as electrodes.
What is microbial fuel cell wastewater treatment?
A microbial fuel cell is a rapidly growing, eco-friendly and green technology. As per this technology, the microorganisms are employed to convert the chemical energy stored in the biodegradable portion of organic matter into direct electric current by simultaneously treating the wastewater.
How are microbial fuel cells made?
4.1 Microbial Fuel Cells. Microbial fuel cells (MFCs) are a new bioelectrochemical process that aims to produce electricity by using the electrons derived from biochemical reactions catalyzed by bacteria.
What materials are hydrogen fuel cells made of?
When the hydrogen fuel is made with renewable energy, such as solar power, the entire process can be completely clean. The main materials used in fuel cells are Nafion, Teflon, Silicone Rubber, Platinum, Graphite, carbon paper, and carbon fiber.
What materials do you need to make a hydrogen fuel cell?
1. The primary components of a fuel cell are an ion conducting electrolyte, a cathode, and an anode, as shown schematically in Fig. 1. In the simplest example, a fuel such as hydrogen is brought into the anode compartment and an oxidant, typically oxygen, into the cathode compartment.
What are the 4 types of microbes?
Current estimates suggest there could be at least 1 billion different species of microbe on Earth, possibly more. Microbial diversity is truly staggering, yet all these microbes can be grouped into five major types: Viruses, Bacteria, Archaea, Fungi, and Protists.
How much power can a microbial fuel cell produce?
The power density that an MFC can typically generate is from 1 to 2000 mW m−24. Therefore, the MFC output voltage and power must be increased for practical uses. So far, several MFCs were simply connected in series or in parallel to overcome the low voltage or power issue.
What are possible applications of the microbial fuel cells?
One such developing technology is microbial fuel cells (MFC) that can produce electricity from organic waste and reduce carbon footprint and environmental pollution. Many industries have adopted this technology for various applications such as wastewater treatment, bioenergy production, and biosensors.
What are microbial fuel cells made of?
Introduction. A microbial fuel cell (MFC) is a bioelectrochemical device that can generate electricity by the use of electrons obtained from the anaerobic oxidation of substrates. Generally, the MFC consists of two parts, an anode and a cathode, which are separated by a proton exchange membrane (PEM).
How does MFC treat water?
Microbial Fuel Cell (MFC) is a sustainable technology that treats wastewater and generates electricity simultaneously while leaving low concentrations of nutrients in the effluent.
What bacteria is used in microbial fuel cells?
Gram-negative microorganisms used in MFC are presented Bacillus violaceus, Escherichia coli, Pseudomonas fluorescens, Proteus vulgaris, Pseudomonas methanica, Desulfuromonas acetoxidans, Geobacter sulfurreducens, Methylovorus dichloromethanicum, Methylovorus mays, Shewanella putrefaciens, Geobacter metallireducens, ...
How does a microbial fuel cell work?
A microbial fuel cell (MFC) is a bio-electrochemical device that harnesses the power of respiring microbes to convert organic matter in waste-water directly into electrical energy. At its core, the MFC is a fuel cell, which transforms chemical energy into electricity using oxidation-reduction reactions. The key difference is that MFCs rely on living biocatalysts to facilitate the movement of electrons throughout their systems instead of the traditional chemically catalysed oxidation of a substrate at the anode and reduction at the cathode. In this field the term substrate is used to describe a substance on which the microorganism acts to produce a chemical reaction, in this case organic matter contained in waste-water, usually in dissolved form.
What is waste water treatment?
Waste treatment is a problem for all human settlements from small villages to large cities. The basic processes developed for waste-water treatment (activated sludge, trickling filters and lagoons) were developed over a century ago, and have changed little with respect to the fundamental approach of oxidising organic matter to remove the organic load on receiving water bodies. The traditional method of aeration produces a water which, although clear of solid matter, is rich in nutrients and has devastating effects when discharged into sea or freshwater. Waste-water treatment remains an economic burden to industries and the public.
How is CO2 converted to methane?
This is a process whereby carbon dioxide is converted to methane using electric current and a microorganism catalyst. The process is usually intended for CO 2 capture or conversion and is usually used to convert surplus energy from renewable sources in to a storable energy carrier. The process can be combined with the microbial fuel cell to convert the CO 2 generated by the fuel cell to methane. Fig. 4 illustrates the process.
How is hydrogen gas produced?
The MEC is based on modifying a microbial fuel cell (MFC) in two ways: adding a small voltage (>0,2 V) to that produced by bacteria at the anode; and by using an oxygen free cathode. The addition of the voltage makes it possible to produce pure hydrogen gas at the cathode. This MEC system is operated as a completely anaerobic reactor. The voltage needed to be added can be produced using power from an MFC. The protons and electrons produced by the bacteria are recombined at the cathode as hydrogen gas, a process called the hydrogen evolution reaction (HER). This is shown in Fig. 4.
What is wastewater used for?
The use of wastewater for energy generation by biodigestion and generation of biogas is a well established process in use at numerous waste-water treatment plants. A new approach, based on microbial fuel cells, which offers a scalable alternative with much potential, is in the development stages. The technique also has an application to acid mine water drainage treatment.
Is oxidation and reduction in MFC understood?
The mechanism of oxidation and reduction in the MFC is not clearly understood , and various reactions have been proposed to explain the process. An example using acetate as the substrate follows:
What is the function of a fuel cell in wastewater?
Microbial fuel cell based wastewater systems employ bioelectrochemical catalytic activity of microbes to produce electricity from the oxidation of organic, and in some cases inorganic, substrates present in urban sewage, agricultural, dairy, food and industrial wastewaters.
Why are microbial fuel cells important?
Microbial fuel cells show the potential for a sustainable route to mitigate the growing energy demands for wastewater treatment and environmental protection. The indigenous exoelectrogenic microbial communities in the MFCs are capable of degrading various forms of wastewaters.
What are MFCs made of?
MFCs can utilize various biodegradable organic compounds originating from agricultural, dairy, domestic (municipal wastewater), food, industrial, and landfill leachates and many others. Earlier studies investigated MFC performances with artificial (synthetic) wastewaters to understand the feasibility of the working principle and the mechanisms to improve energy recovery and organic removal efficiencies. Recent studies focused on using actual wastewaters from various aforementioned waste sources to determine practical feasibility of MFCs, because actual wastewater composition is quite different from the synthetic wastewaters.
Why should environmental performance and cost objectives be addressed?
Environmental performance and cost objectives should be well addressed in order to promote the MFC technology as an alternative wastewater treatment technology. A few studies focused on these objectives to determine the plausible goals for the near future. The following sections summarize the outcomes from recent literature.
What are the processes that produce electricity in MFCs?
Electricity production in MFCs is the result of oxidation–reduction reactions that result in electron release, transfer and acceptance through biochemical or electrochemical reactions at the electrodes in the anode and cathode chambers. One acts as an electron donor while the other essentially serves as an electron acceptor. The chemical compounds that are responsible for accepting electrons are called terminal electron acceptors (TEA). The following oxidation–reduction reactions (Eqs. (6), (7), (8), (9), (10), (11), (12), (13), (14), (15), (16), (17), (18)) represent possible bioelectro-chemical reactions in microbial fuel cells generating electricity utilizing wastewater as a substrate (electron donor) and other pollutants such as nitrates, phosphates, and others as electron acceptors.
What is algae based wastewater treatment?
Algae based wastewater treatment has shown promise to be an energy-positive process (see Fig. 2 ). Phototrophic (algae based) technologies can be designed as high rate algal pond (HRAP), photobioreactor (PBR), stirred tank reactor, waste stabilization pond (WSP), and algal turf scrubber (ATS). These systems can produce energy-rich algal biomass that can be used as feedstock for high value energy products. A comparison between the anaerobic and phototrophic technologies showed that the average bioenergy feedstock production by phototrophic technologies ranged from 1200 to 4700 kJ per capita per day or 3400–13,000 kJ/m 3 (exceeding anaerobic technologies and, at times, the energetic content of the influent organic carbon), with usable energy production dependent upon downstream conversion to fuels ( Shoener et al., 2014 ). Table 1 shows the energy production potential (kJ) per g of nutrients removed from wastewater via different energy-conversion processes such as hydrothermal liquefaction (HTL), anaerobic digestion, transesterification and combustion. More details of this analysis are presented in Shoener et al. (2014).
What is wastewater treatment?
Wastewater treatment is not only a concern for developing countries but it continues to be the most basic sanitation need to protect the environment and the water bodies that serve as drinking water sources around the world. Wastewater treatment accounts for about 3–4% of the United States' electrical energy load, which is approximately 110 TWh/year, or equivalent to 9.6 million households' annual electricity use ( McCarty et al., 2011 ). In UK, wastewater treatment requires approximately 6.34 GWh of electricity, almost 1% of the average daily electricity consumption of England and Wales ( DTI, 2005 ). Wastewater treatment requires about 0.5–2 kWh/m 3 which depends on the process and wastewater composition and interestingly, it contains about 3–10 times the energy required to treat it ( Gude, 2015a ). The energy locked in wastewater is mainly present in three forms: 1 – organic matter (∼1.79 kWh/m 3 ); 2 – nutritional elements such as nitrogen, phosphorous (∼0.7 kWh/m 3 ); and 3 – thermal energy (∼7 kWh/m 3) ( McCarty et al., 2011 ). Energy available in domestic wastewater source can be classified as chemical and thermal energy. Chemical energy (∼26%) is available in the forms of carbon (measured as chemical oxygen demand, COD) and nutrient compounds (nitrogen, N and phosphorous, P). Thermal energy holds a major portion of this energy potential (74%). Chemical energy can be efficiently harvested while thermal energy may not be extracted except by use of a heat pump and subject to wastewater source temperature. By extracting this hidden chemical energy, wastewater treatment can be turned into an energy-yielding or energy-independent process rather than an energy consuming process while eliminating environmental pollution ( Gude et al., 2013 ).
How do municipal plants treat sewage?
The majority of municipal plants treat the settled sewage liquor using aerobic biological processes. To be effective, the biota require both oxygen and food to live. The bacteria and protozoa consume biodegradable soluble organic contaminants (e.g. sugars, fats, organic short-chain carbon molecules, etc.) and bind much of the less soluble fractions into floc. Secondary treatment systems are classified as fixed-film or suspended-growth.
What is a primary sedimentation tank?
In the primary sedimentation stage, tanks commonly called “primary clarifiers” or “primary sedimentation tanks” are used to settle sludge while grease and oils rise to the surface and are skimmed off. Primary settling tanks are usually equipped with mechanically driven scrapers which continually drive the collected sludge towards a hopper in the base of the tank where it is pumped to sludge treatment facilities. Grease and oil from the floating material can sometimes be recovered for saponification. The dimensions of the tank should be designed to effect removal of a high percentage of the floatables and sludge. A typical sedimentation tank may remove from 60% to 65% of suspended solids, and from 30% to 35% of biochemical oxygen demand (BOD) from the sewage.
What is tertiary treatment?
Finally, the purpose of tertiary treatment is to provide a final treatment stage to raise effluent quality before it is discharged to the receiving environment (sea, river, lake, ground, etc.). More than one tertiary treatment process may be used at any treatment plant. If disinfection is performed, it is always the final process. It is also called “effluent polishing”. The organic matter concentration in wastewater is usually evaluated in terms of either its biochemical oxygen demand (BOD) in a five day test (BOD5) or its chemical oxygen demand (COD) in a rapid chemical oxidation test. Total BOD or COD can be viewed as consisting of two fractions: soluble BOD (sBOD) and particulate BOD (pBOD). Most pBOD is removed in the primary clarifier sludge and sBOD is converted to bacterial biomass (Logan, 2008).
What temperature does anaerobic digestion take place?
Anaerobic digestion requires 30–50°C for optimal operation but MFCs are known to operate well at ambient temperature (Ahn and Logan, 2010; Jadhav and Ghangrekar, 2009; Min et al., 2008). Organic removal increased but the electricity production decreased, which might be due to increased activity of methanogens. The additional heating system to maintain temperature may not be necessary for energy recovery or wastewater treatment using MFC technology. The MFC operated at a mesophilic temperature of 35 ± 5°C during the first 102 days. During this period the maximum power density reached was (4.41 W·m-3) using 1000Ω at 37°C. A constant temperature of 40°C was maintained for the following days, obtaining a maximum power density of (6.53 W·m-3) with 600Ω. Under this last scheme the temperature was increased by 5°C, obtaining 6.54 W·m-3. We should note that the temperature increase to 45°C did not lead to significant increases in power density, given that the result obtained is very similar to the one reached at an operational temperature of 40°C. These results reflect the strong influence of the external resistance used, together with an optimum operational temperature (Rozendal et al., 2006).
What do you need to make a mudwatt?
To make a MudWatt, you will need: MudWatt Classic, MudWatt Science Fair Pack, or MudWatt Classroom Pack. Mud. Any container (if you're using a different vessel) How the MudWatt Works: The MudWatt is a fun and educational science kit that uses the micro-organisms naturally found in soil to generate electricity.
How to make a swamp goo?
Step 1: Making Mud. Put on gloves and find 3-4 handfuls of soil or swamp goo--the smell ier the better! Make sure your soil is saturated but not soupy by either adding or pouring off water. Optional: Add extra nutrients to your soil, such as MudWatt packaging, shredded paper products, or food from your fridge.
How to make a mud anode?
Pack an even layer of mud into the bottom of your container, at least 1cm deep. Place the anode (green) you constructed in Step 3 on top of the mud, pressing it down firmly to squeeze out air bubbles. Fill your container with more mud, at least 5cm deep, pressing down firmly to squeeze out air bubbles. Let your mud rest for a few minutes and drain any excess liquid. Finally, place the cathode (orange) gently on top of the mud. Do not cover the cathode with mud.
What is a mudwatt battery?
The MudWatt microbial fuel cell (affectionately dubbed the "Dirt Battery") is a device that uses bacteria to convert the organic matter found in mud into electricity. This Instructable will walk you through making your own microbial fuel cell using any MudWatt Science Kit.
What is a microbial fuel cell?
Microbial fuel cells and their modified derivative systems are breakthrough methods to treat biodegradable effluents efficiently with simultaneous generation of electricity, thus catering to the rapidly growing demands of energy production and wastewater treatment.
What is the function of a microbial desalination cell?
The function of a microbial desalination cells (MDC) is primarily ion removal from water to reduce its salinity. There are other widely accepted methods as well, which can give fresh drinking water by desalination of seawater, like reverse osmosis (RO). The problem with RO is that it requires high pressure, or, in other words, high energy input (about 3–4 kWh/m 3 of seawater). Other distillation techniques require even more energy input—multi-stage flash distillation (MSF), multi-effect distillation (MED), membrane distillation [228], etc. [ 169 ]. To do so, the MDC has to generate power by effluent treatment.
How does mass transfer loss occur?
Mass transfer losses are the losses that occur due to the hindrance in the flow of electrons through the conducting materials such as the electrode (i.e., current flowing through the material) due to the mass transfer to or/and from the electrodes [ 212 ]. Usually, this occurs in the presence of high current densities due to incomplete and limited mass transfer of chemical species by diffusion towards the electrode. As a result of insufficient mass transfer, the reactant depletes or causes the product to accumulate. To reduce these mass transfer losses, maintaining high concentrations and even distribution of oxidants like O 2 across the cathode compartment might be useful. In addition, optimization of MFC operating conditions, electrode material, and cathode compartment design can reduce losses due to mass transfer.
What is the process of treating organic waste?
A widely used process for the treatment of organic waste is anaerobic bacterial digestion. In the last few decades, due to their mild operating conditions, where biodegradable substrates can be used as a fuel, great attention has been paid to microbial fuel cells (MFCs).
What is the role of microorganisms in electrochemical reactions?
The inclusion of microorganisms responsible for catalyzing electrochemical reactions gives these cells a degree of complexity that can exceed that of complex electrochemical systems that are already in operation (e.g., batteries, fuel cells, and supercapacitors).
Is wastewater a source of energy?
Although wastewater is considered to be a profitable source of energy, pure water and fertilizers, its treatment technologies have many output-related constraints [ 13 ]. Carbon neutral and renewable energy technologies are the present needs of our times.
Is hydrogen a renewable resource?
Biohydrogen production in MFCs. Hydrogen is recognized as an impermanent renewable energy carrier. Much focus is paid to the worldwide use of H 2 as a source of energy fuel. Its advantages are numerous: it is clean, efficient, and renewable, and generates no toxic by-product.
What is a microbial fuel cell?
The microbial fuel cell is a bio-electrochemical system in which bacteria are used to convert organic material into electricity. There exist many different microbial fuel cell designs such as one-chambered or two-chambered MFCs.
What are the two types of microbial fuel cells?
There are two kinds of microbial fuel cells: mediator and mediator-less. In a mediator microbial fuel cell, the bacteria are electrochemically inactive. The bacteria digest the organic material and create electrons. However, the bacteria have no mechanism to rid themselves of the electrons.
What is the purpose of a proton exchange membrane in a fuel cell?
Diagram of a microbial fuel cell that uses a proton-exchange membrane to allow hydrogen ions to pass between the anode and cathode side of the cell. Incoming waste water brings bacteria which attach to an anode and produce electrons and hydrogen ions.
What are the components of a fuel cell?
The traditional H-shaped two-chambered microbial fuel cell is made of several components: the two electrodes (the anode and the cathode ), a proton-exchange membrane (PEM) and an external circuit. The anode chamber holds the bacteria and organic material in an anaerobic (without oxygen) environment.
How to make conductive salt solution?
Make a conductive salt solution using the water sample from the 1-gallon jug. Measure out 12 cups of stream water into the large bowl. Add 6 Tbsp. of salt to the bowl and stir with a spoon until the salt has been dissolved. Fill the cathode chambers of the three microbial fuel cells with the salt solution.
What is the salt bridge in a fuel cell?
The PEM or salt bridge separates the anode and cathode chambers, but at the same time allows protons to move from one electrode chamber into the other. At the cathode, the protons and electrons combine with oxygen to create water. All the processes happening in a microbial fuel cell are summarized in Figure 1.
What is the role of bacteria in a fuel cell?
In a mediator-less microbial fuel cell, the bacteria are electrochemically active. The electrochemically active bacteria, also called electrogenic bacteria carry the electrons they create through digestion of organic material to the electrode.