Bacteria fuel-producing

Sulfate-reducing bacteria (SRB) can live in water bottoms of fuel storage tanks. These bacteria can produce growth plaques on metal surfaces and can live in corrosion pits in metal. Hydrogen sulfide is a product of SRB metabolism and can contaminate fuel stored in tanks. 

Doran JB, Ciipe J, Sutton M, Foster B. (2000). Fermentations of pectin-rich biomass with recombinant bacteria to produce fuel ethanol. Appl Biochem Biotechnol, 84—86, 141-152. 

In 2005, two research groups independendy found that bacteria could produce hydrogen in an electrolysis process based on a microbial fuel cell (MFC) (Logan et al., 2008). The device is called a microbial electrolysis cell (MEC), and the microbes are exoelectrogens because they release electrons instead of hydrogen. The half reactions at anode and cathode of MFCs for conversion of hydrogen from acetate are ... 

Landfill G as Recovery. This process has emerged from the need to better manage landfill operations. Landfill gas is produced naturally anaerobic bacteria convert the disposed organic matter into methane, carbon monoxide, and other gases. The quantity of methane gas is substantial and could be utilized as fuel, but generally is not. Most of the methane simply leaks into the surrounding atmosphere. 

Biogas is produced by the bacteria in the form of small bubbles these float upward through the sludge bed/blanket, providing a good mixing action. When the biogas reaches the top of the reactor, it is collected and used as a fuel. 

This process is an extension of the anaerobic treatment of waste diseussed in Chapter 2, and is also similar to the natural process operating in landfill sites, which evolves methane. By treatment of biomass with bacteria in the absence of air a gas rich in methane can be produced a typical digester may produce over 300 m of gas containing over 50% methane per tonne of dry biomass. The economics of biogas generation for use as a fuel are currently unfavourable. The plants that do exist have been built because of the need to treat waste such as sewage sludge. 

Besides the aerobic microorganisms there are also anaerobic ones. These exist and multiply where no dissolved oxygen is present. Saprophytic bacteria produce organic acids and alcohols. The methane bacteria will then convert these compounds into cells plus carbon dioxide and methane. The methane may be recovered and binned as fuel. If any sulfur is present it will eventually be converted to H2S. 

Methane is produced by bacteria under anaerobic conditions in wet environments such as wetlands, swamps and rice fields. It is also produced in the stomachs of cattle and by termites. Typical anthropogenic sources are from fossil fuels such as coal mining and as a byproduct in the burning of biomass. The latter sources are considerably heavier in C than the former. Recently, Keppler et al. (2006) demonstrated that methane is formed in terrestrial plants under oxic conditions by an unknown mechanism. The size of this methane source is stiU unknown but it might play an important role for the methane cycle. 

Particulate matter is the term used to describe solid particles and liquid droplets found in the atmosphere. Particulates are produced by a host of natural and anthropogenic sources. Mist and fog are both forms of natural particulates, as are windblown soil, dust, smoke from forest fires, and biological objects, such as bacteria, fungal spores, and pollen. The incomplete combustion of fossil fuels is one of the most important anthropogenic (human-made) sources of particulates. Such processes release unhurned carbon particles, oxides of sulfur and nitrogen, and a host of organic compounds into the air. 

Lactose is readily fermented by lactic acid bacteria, especially Lactococcus spp. and Lactobacillus spp., to lactic acid, and by some species of yeast, e.g. Kluyveromyces spp., to ethanol (Figure 2.27). Lactic acid may be used as a food acidulant, as a component in the manufacture of plastics, or converted to ammonium lactate as a source of nitrogen for animal nutrition. It can be converted to propionic acid, which has many food applications, by Propionibacterium spp. Potable ethanol is being produced commercially from lactose in whey or UF permeate. The ethanol may also be used for industrial purposes or as a fuel but is probably not cost-competitive with ethanol produced by fermentation of sucrose or chemically. The ethanol may also be oxidized to acetic acid. The mother liquor remaining from the production of lactic acid or ethanol may be subjected to anaerobic digestion with the production of methane (CH4) for use as a fuel several such plants are in commercial use. 

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