Bioconversion
Encyclopedia
The term Bioconversion, also known as biotransformation refers to the use of live organisms often microorganisms to carry out a chemical reaction that is more costly or not feasible nonbiologically. These organisms converts a substance to a chemically modified form. An example is the industrial production of cortisone
Cortisone
Cortisone is a steroid hormone. It is one of the main hormones released by the adrenal gland in response to stress. In chemical structure, it is a corticosteroid closely related to corticosterone. It is used to treat a variety of ailments and can be administered intravenously, orally,...

. One step is the bioconversion of Progesterone
Progesterone
Progesterone also known as P4 is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species...

 to 11-alpha-Hydroxyprogesterone by Rhizopus nigricans
Rhizopus nigricans
Rhizopus nigricans is a fungus commonly known as bread mold and is the most common species of Rhizopus. It is found on old food and in soils and even in children's sandboxes. The genus contains some 50 species and bread mold is sometimes confused with species of Mucor or other species of Rhizopus...

.


Another example is the conversion
Conversion (chemistry)
In chemistry, the phrase conversion has several meanings* specifically the property 'X' related to the yield 'Y' by multiplication with the selectivity 'S', i.e. the mathematical definition X * S = Y, all calculated on a molar basis; e.g...

 of organic materials, such as plant or animal waste, into usable products or energy sources by biological processes or agents, such as certain microorganism
Microorganism
A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...

s, some Detritivore
Detritivore
Detritivores, also known as detritophages or detritus feeders or detritus eaters or saprophages, are heterotrophs that obtain nutrients by consuming detritus . By doing so, they contribute to decomposition and the nutrient cycles...

s or enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

s.

New cellulosic ethanol
Cellulosic ethanol
Cellulosic ethanol is a biofuel produced from wood, grasses, or the non-edible parts of plants.It is a type of biofuel produced from lignocellulose, a structural material that comprises much of the mass of plants. Lignocellulose is composed mainly of cellulose, hemicellulose and lignin...

 conversion processes have enabled the variety and volume of feedstock that can be bioconverted to expand rapidly. Feedstock now includes materials derived from plant or animal waste such as paper, auto-fluff, tires, fabric, construction materials, municipal solid waste
Municipal solid waste
Municipal solid waste , commonly known as trash or garbage , refuse or rubbish is a waste type consisting of everyday items we consume and discard. It predominantly includes food wastes, yard wastes, containers and product packaging, and other miscellaneous inorganic wastes from residential,...

 (MSW), sludge
Sludge
Sludge refers to the residual, semi-solid material left from industrial wastewater, or sewage treatment processes. It can also refer to the settled suspension obtained from conventional drinking water treatment, and numerous other industrial processes...

, sewage
Sewage
Sewage is water-carried waste, in solution or suspension, that is intended to be removed from a community. Also known as wastewater, it is more than 99% water and is characterized by volume or rate of flow, physical condition, chemical constituents and the bacteriological organisms that it contains...

, etc.

Three different processes for bioconversion

1 - Enzymatic hydrolysis - a single source of feedstock, switchgrass for example, is mixed with strong enzymes which convert a portion of cellulosic material into sugars which can then be fermented into ethanol. Genencor and Novozymes are two companies that have received United States government Department of Energy funding for research into reducing the cost of cellulase, a key enzyme in the production cellulosic ethanol by this process.

2 - Synthesis gas fermentation - a blend of feedstock, not exceeding 30% water, is gasified in a closed environment into a syngas
Syngas
Syngas is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen. Examples of production methods include steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, the gasification of coal, biomass, and in some types of waste-to-energy...

 containing mostly carbon monoxide and hydrogen. The cooled syngas
Syngas
Syngas is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen. Examples of production methods include steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, the gasification of coal, biomass, and in some types of waste-to-energy...

 is then converted into usable products through exposure to bacteria or other catalysts. BRI Energy, LLC is a company whose pilot plant in Fayetteville, Arkansas is currently using synthesis gas fermentation to convert a variety of waste into ethanol. After gasification, anaerobic bacteria (Clostridium ljungdahlii) are used to convert the syngas (CO
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

, CO2
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

, and H2
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

) into ethanol. The heat generated by gasification is also used to co-generate excess electricity.

3 - Black Soldier Fly
Hermetia illucens
The black soldier fly, Hermetia illucens, is a common and widespread fly of the family Stratiomyidae, whose larvae are common detritivores in compost heaps...

or Grub Composting
is a sustainable technology that employs organisms that feed on organic matter to reduce and convert organic waste in to live feedstock for the livestock farming and the biodiesel industry EAWAG. Organizations pioneering this novel approach to waste management are ESR International, Prota Culture and BIOCONVERSION to meet large scale organic waste management needs and environmental sustainability in both urban and livestock farming reality.
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