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.
Are microbial fuel cells efficient for treatment of wastewaters?
DOI: 10.2166/wst.2006.702 Abstract Microbial fuel cells (MFCs) are emerging as promising technology for the treatment of wastewaters. The potential energy conversion efficiencies are examined.
How does a microbial fuel cell work?
Microbial fuel cells harness the power of bacteria and convert energy released in metabolic reactions into electrical energy. The actual cell consists of two electrodes separated by a semi-permeable membrane submersed in an electrolyte solution. Fig. 1 depicts a typical MFC set-up in a research laboratory.
What is fosters’ microbial fuel cell project?
Partnered with the University of Queensland, Fosters’ plans to improve the MFC’s cleaning power and electrical output and eventually build a 660 gallon, 2 Kilowatt MFC that cleans all of the company’s wastewater. The power generated from cleaning the brewery wastewater is expected to pay for the initial cost of the Microbial Fuel Cell in ten years.
Is there a single fuel cell reactor for coking wastewater treatment?
Wu D, Yi X, Tang R, Feng C, Wei C (2018a) Single microbial fuel cell reactor for coking wastewater treatment: simultaneous carbon and nitrogen removal with zero alkaline consumption. Sci Total Environ 621:497–506
How do microbial fuel cells work in wastewater treatment?
Microbial fuel cells (MFCs) can provide an answer to several of the problems which traditional wastewater treatment faces. They enable the recovery of energy out of the wastewater, while limiting both the energy input and the excess sludge production (Rabaey and Verstraete, 2005).
How do microbes treat waste water?
Aerobic bacteria use oxygen, which is added mechanically, to break down wastewater contaminants, converting it into energy. Bacteria use this energy to grow and reproduce. Anaerobic bacteria obtain oxygen from their food source. As anaerobic bacteria break down sludge, they produce methane gas.
How does a microbial fuel cell work?
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. The energy generated by MFCs is expected to supply enough energy to partially cover the energy demand in urban WWTPs.
How does a waste water treatment work?
There are two basic stages in the treat- ment of wastes, primary and secondary, which are outlined here. In the primary stage, solids are allowed to settle and removed from wastewater. The secondary stage uses biological processes to further purify wastewater. Sometimes, these stages are combined into one operation.
How are microbes effectively employed in sewage treatment explain?
These microbes consume the organic mass of the waste water and utilize the nutrients from sewage for their growth, ultimately enhancing the cleaning action of waste water. The treatment can restore water quality and increases the self-cleansing capacity of the water body.
What are the steps of wastewater treatment?
The Wastewater Treatment ProcessStage One — Bar Screening. ... Stage Two — Screening. ... Stage Three — Primary Clarifier. ... Stage Four — Aeration. ... Stage Five — Secondary Clarifier. ... Stage Six — Chlorination (Disinfection) ... Stage Seven — Water Analysis & Testing. ... Stage Eight — Effluent Disposal.
How does a microbial desalination cell work?
Microbial Desalination Cell (MDC) is a novel technology able to produce sustainable drinking water by using the energy provided from the metabolism of electroactive bacteria when organic matter is degraded, allowing simultaneous desalination of water, treatment of waste water and production of electricity.
Where are microbial fuel cells used?
Sediment microbial fuel cells (SMFCs) have been applied for wastewater treatment. Simple SMFCs can generate energy while decontaminating wastewater. Most such SMFCs contain plants to mimic constructed wetlands.
What is a microbial cell?
The term microbial cells are very general. This term used to describe many different types of life forms, with dramatically different sizes and characteristics: bacteria, archaea, fungi, and protists.
What are the 5 stages of water treatment?
Public water systems often use a series of water treatment steps that include coagulation, flocculation, sedimentation, filtration, and disinfection.
What methods are used in primary treatment of wastewater?
There are three basic biological treatment methods: the trickling filter, the activated sludge process, and the oxidation pond.
How is water treated at a wastewater treatment plant?
As solid material decays, it uses up oxygen, which is needed by the plants and animals living in the water. "Primary treatment" removes about 60 percent of suspended solids from wastewater. This treatment also involves aerating (stirring up) the wastewater, to put oxygen back in.
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 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 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).