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Topic: Anaerobic digestion

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	Anaerobic digestion - Wikipedia, the free encyclopedia
		Anaerobic digestion is the breakdown of organic matter by bacteria in the absence of oxygen.
		Anaerobic digesters have been around for a long time, and they are commonly used for sewage treatment and for managing animal waste.
		If the digested materials include low levels of toxic heavy metals or synthetic organic materials such as pesticides or PCBs, the effect of digestion is to significantly concentrate such materials in the digester liquor in order to dispose of this liquid properly.
	en.wikipedia.org /wiki/Anaerobic_digestion (1204 words)

	Anaerobic Digestion of Animal Wastes: Factors to Consider
		The key by-products of anaerobic digestion include digested solids (useful as a soil amendment) and methane, the primary component of "bio-gas," which can be used to fuel a variety of cooking, heating, cooling, and lighting applications, as well as to generate electricity.
		Thermophilic digestion yields higher levels of gas and kills more pathogenic bacteria, but it has certain disadvantages as well, the greatest of which is the added cost of maintaining higher temperatures and keeping the digester stirred to maximize contact between the bacteria and the organic matter.
		Anaerobic digesters are installed for various reasons-as a means of resolving environmental problems, as a means of economically re-using an otherwise wasted resource, as a source of additional revenue.
	www.attra.org /attra-pub/anaerobic.html (3554 words)

	Methane Gas Recovery on the Farm (Wisconsin Public Service Corporation) (Site not responding. Last check: 2007-10-21)
		Anaerobic digestion systems are also a way to handle the increased pressure on livestock operations to control odors.
		Anaerobic means "without oxygen," therefore, an anaerobic digester is an enclosed tank that excludes oxygen.
		In a plug-flow digester, the solids in manure with lower than desirable solids concentrations are poorly digested because they gradually settle to the bottom of the tank.
	www.wisconsinpublicservice.com /farm/gasrecovery.asp (1022 words)

	PIER Renewables -- Anaerobic Digestion
		Anaerobic digestion (AD) is a biological process in which biodegradable organic matters are broken-down by bacteria into biogas, which consists of methane (CH4), carbon dioxide (CO2), and other trace amount of gases.
		Plug-flow digesters are usually operated with a total solid concentration of 11%-13% at the mesophilic temperature range, with a HRT from 20-30 days.
		Larger, centralized anaerobic digestion plants, which utilize animal manure and industry waste in a single facility, are a newer development and most prevalent in Denmark where there are 18 plants (worldwide there are 50 or so, all within Europe).
	www.energy.ca.gov /pier/renewable/biomass/anaerobic_digestion (1665 words)

	Anaerobic Digestion
		Anaerobic digestion is a biological process that produces a gas principally composed of methane (CH4) and carbon dioxide (CO2) otherwise known as biogas.
		Process temperature affects the rate of digestion and should be maintained in the mesophillic range (95 to 105 degrees Fahrenheit) with an optimum of 100 degrees F. It is possible to operate in the thermophillic range (135 to 145 degrees F), but the digestion process is subject to upset if not closely monitored.
		Many anaerobic digestion technologies are commercially available and have been demonstrated for use with agricultural wastes and for treating municipal and industrial wastewater.
	www.energy.ca.gov /development/biomass/anaerobic.html (451 words)

	Methane Generation From Livestock Wastes (Site not responding. Last check: 2007-10-21)
		Anaerobic fermentation or digestion is the most promising process for converting organic materials to methane and other gases.
		The extraction of energy from wastes using anaerobic digestion to produce bio-gas is not new and the general technology is well known.
		Anaerobic digestion is a two-part process and each part is performed by a specific group of organisms.
	www.ext.colostate.edu /pubs/farmmgt/05002.html (1694 words)

	G1881 Generating Methane Gas From Manure, MU Extension
		The gas obtained in anaerobic digestion of animal wastes is a mixture of carbon dioxide and methane with trace amounts of hydrogen sulfide and hydrogen gas.
		The design volume of an anaerobic digester is sized according to the amount of volatile solids that must be treated daily and the period of time the material remains in the digester (detention time).
		A digester must be loaded with manure on a regular basis to ensure a continuous supply of food for the anaerobic bacteria.
	www.muextension.missouri.edu /xplor/agguides/agengin/g01881.htm (3180 words)

	Anaerobic Digestion (Site not responding. Last check: 2007-10-21)
		Anaerobic digestion is the breakdown of complex organic material by microorganisms in the absence of oxygen.
		Anaerobic digestion may be a viable manure treatment and handling method for dairy farms of a particular size.
		Advantages of anaerobic digestion include ability to generate electricity and heat (through the combustion of the biogas), odor control, reduction of pathogens, ability to use digested (separated) solids as bedding, and the ability to spread digested (separated) liquid effluent at different times and different places than was previously socially acceptable.
	www.bee.cornell.edu /extension/manure/anaerobic_digestion.htm (426 words)

	Anaerobic Digestion of Corn Stover and Swine Manure
		Anaerobic Digestion of Corn Stover and Swine Manure
		We are investigating the use of on-farm or small community anaerobic digestion of corn stover or mixtures of stover and swine manure to methane gas that can be combusted for heat or used to fuel engines generating rectified electricity for on-site use or fed into utility power lines.
		In single-stage digestion neither of the two groups have their optimum conditions for growth, but the most critical requirement is pH for the methanogenic bacteria so the reactor is usually run so that the pH is about 6.8.
	www.energy.iastate.edu /renewable/biomass/cs-anerobic.html (912 words)

	Feature (Site not responding. Last check: 2007-10-21)
		The anaerobic digestion process is one of the established technologies for sustainable processing of residues and wastes in the agro-food industry.
		Anaerobic micro-organisms digest the organic matter in the absence of oxygen, to produce Methane, Carbon dioxide and solid residue.
		Anaerobic digestion refers to the various reactions and interactions that, takes place converting complex organic materials to produce biogas, nutrient rich solids and liquid in an oxygen free environment.
	www.dailynews.lk /2005/09/29/fea02.htm (1221 words)

	Anaerobic Digestion in Rural China
		Anaerobic digestion has the advantages of producing energy, producing high quality fertilizer and also preventing the transmission of disease.
		In addition to reducing the efficiency of the digester, the crust needed to be removed in an annual clean-out.
		Anaerobically digested fertilizer also increases yields compared to material composted aerobically presumably due to the conservation of nitrogen in an anaerobic system.
	www.cityfarmer.org /biogasPaul.html (2422 words)

	Anaerobic Digestion
		Anaerobic digestion is the bacterial breakdown of organic materials in the absence of oxygen.
		Anaerobic processes can occur naturally or in a controlled environment such as a biogas plant.
		In controlled environments, organic materials such as sewage sludge and other relatively wet organic materials, along with various types of bacteria, are put in an airtight container called a digester where the process occurs.
	www.ciwmb.ca.gov /Organics/Conversion/Anaerobic (134 words)

	AE-105
		Methane generation is accomplished by anaerobic digestion (biological oxidation in the absence of oxygen) of organic substances such as livestock waste and plant refuse.
		Insulate the digester surface to a level of at least R=10 where it is in contact with the ground and to at least R=20 where it is in contact with air (R is a measure of a material's ability to resist the flow of heat.
		Digestion is possible at 70F because bacteria are not removed from the effluent and the large numbers of bacteria offset the reduced biological activity at the low temperature.
	pasture.ecn.purdue.edu /%7Eepados/swine/pubs/methane.htm (5673 words)

	NCSU: Animal Science - 1995 Annual Report (Site not responding. Last check: 2007-10-21)
		Anaerobic digestion of animal manures for the production of biogas has been extensively investigated during the previous two decades, in part, due to energy considerations.
		Thus, the purpose of this laboratory-scale investigation was 1) to determine the feasibility of biogas generationusing swine manure as the sole organic substrate under thermophilic (50°C) anaerobic fermentation treatment conditions and 2) to determine the effect of thermophilic anaerobic treatment of swine manure on odor intensity, irritation intensity and odor quality (pleasantness).
		Fresh swine feces was mixed to the desired volatile solids (VS) content, de-aerated by nitrogen sparging and added into 1-L anaerobic digesters maintained at 50°C. Swine manure, rumen fluid, and mud collected from the basin of a primary treatment lagoon for swine waste were used as the sources of bacteria to initiate the digester cultures.
	www.cals.ncsu.edu /an_sci/annrep95/swine/swin9514.html (757 words)

	Anaerobic Manure Digestion Information and Resources
		The Haubenschild Farms digester is a covered 350,000-gallon concrete tank installed in the ground, with suspended heating pipes to heat the manure inside the digester where bacteria breaks down the manure, creating methane.
		The manual is divided into three parts: the first describes the operation and waste management practices of Idaho dairies; the second introduces anaerobic digestion and the anaerobic digestion process suitable for dairy waste; and, the third presents typical design applications for different type of dairies and establishes the cost and benefits of the facilities.
		The fixed-film digester developed at the University of Florida was designed specifically to treat the liquid fraction of flushed dairy manure, with a portion of the digester biogas being utilized to heat water for use in milking parlor.
	www.mda.state.mn.us /feedlots/digester.htm (3537 words)

	The Corporation For Future Resources \| anaerobic digestion \| CFR \| biomass \| renewable energy
		Leucaena when used as the anaerobic fermentation feedstock, undergoes, on a dry basis, 60% conversion to methane rich gas and carbon dioxide –; the unconverted solids form the core of the anaerobic compost – the major ingredient of an organic fertilizer.
		Of note is that there are sufficient agricultural lands even in Florida such that Leucaena based anaerobic fermentation systems could assist in not only supplying a significant fraction of the energy and fertilizer used in Florida while also removing substantial quantities of atmospheric carbon dioxide.
		Anaerobic Fermentation eliminates the adverse environmental impact of burning and crop harvest residue decay with the latter, thereby, reducing greenhouse effects due to methane released to atmosphere upon decomposition of tilled crops.
	www.pipeline.com /~dglickd/CFR.html (1000 words)

	Anaerobic Digester Lagoon with Methane Gas Recovery: First year Management and Economics (Site not responding. Last check: 2007-10-21)
		Anaerobic lagoons are perhaps the most trouble free, low maintenance systems available for treatment of animal waste.
		A properly designed, constructed and operated anaerobic digester is a low maintenance system that is very forgiving and not likely to create emergency situations that can be expected with many alternative waste management systems.
		Adding methane recovery to the anaerobic digester increases maintenance but even in the event of failure of the gas collection system, it will not interrupt the waste stream and digestion process.
	www.ctic.purdue.edu /core4/nutrient/manuremgmt/Paper31.html (1835 words)

	Latest Progress In Anaerobic Digestion
		In early May 1972, the digester was seeded with 6,000 gallons of sludge from the town’s municipal waste digester and two hours of manure flow from the swine facility.
		An often vital component of a plug-flow digester is the mixing pit, which allows the TS concentration of the manure to be adjusted to a range of 11 to 13 percent by dilution with water.
		The complete-mix and plug-flow digestion technologies are not suited for use on farms that use hydraulic flushing systems to remove manure and anaerobic lagoons to treat waste.
	www.biocycle.net /BCArticles/1999/07992.html (2142 words)

	Anaerobic Digestion (AD) Technical Pages. Anaerobic treatment and disposal.
		The popularity of Anaerobic Digestion is set to rise in 2005, with UK Government and EU support.
		Anaerobic Digestion (AD) is a process whereby organic waste is broken down in a controlled, oxygen free environment by bacteria naturally occurring in the waste material.
		The residual nutrient rich liquor and digestate is suitable for use as fertiliser on the farmland surrounding such a plant, reducing the need for artificial fertiliser.
	www.anaerobic-digestion.com (381 words)

	Sewage treatment using anaerobic digestion in a Biotank
		Anaerobic digestion is a complex biochemical reaction carried out in a number of steps by several types of micro-organisms that require little or no oxygen to live.
		After completion of the anaerobic digestion steps, the pollutants in the wastewater are transformed into methane (CH), carbon dioxide (CO) and a small amount of biosolids.
		This is one more reason for applying an aerobic second stage, which removes the residual nutrients which would otherwise cause eutrophication of the river in which the treated effluent is discharged.
	www.biotank.co.uk /anaerobic_digestion.htm (591 words)

	Anaerobic Digestion
		Anaerobic digestion benefits the agricultural facility as a waste management tool, and can be a profitable alternative for a never ending resource.
		Enclosed anaerobic digesters can be a heated tank or an enclosed lagoon that exclude oxygen from the process.
		Gases produces be the digester are trapped and can later be burned to produce heat and electricity for the operation or for sale to a utility.
	www.idwr.state.id.us /energy/aim/anaerobic.htm (269 words)

	G1881 Generating Methane Gas From Manure, MU Extension
		Mixing aids digestion by continually bringing the bacteria in contact with the waste material and by distributing the heat more uniformly.
		The contents of the digester should be monitored at regular intervals.
		A digester will also be an integral part of the waste management system.
	muextension.missouri.edu /explore/agguides/agengin/g01881.htm (3180 words)

	Waste Management Publications: ABEN-97 (Site not responding. Last check: 2007-10-21)
		Anaerobic digestion of dairy waste, whether on-site or in a centralized facility, is a method that can reduce odor, nutrient runoff, and emission of greenhouse gases (methane and carbon dioxide).This publication summarizes the results of a one-year study of anaerobic digestion options in York, New York.
		Anaerobic digestion of dairy waste, whether on-site or in a centralized facility, is a method that can reduce odor, nutrient runoff, and emission of greenhouse gases (methane and carbon dioxide).
		Presenting a new economic analysis and summarizing the opportunities and challenges of anaerobic digestion, the report will be a useful resource for agricultural engineers, dairy producers and their advisors, and others interested in options for animal waste treatment.
	www.nraes.org /publications/aben97.html (799 words)

	Creating Fuel from Manure is a Hot Topic—Again (Site not responding. Last check: 2007-10-21)
		During the energy crisis then, consideration was given to anaerobic digestion of manure as a potential fuel source.
		In the controlled anaerobic digestion process, bacteria break down organic matter (manure is a great source) in an oxygen-free environment.
		The multiple benefits of the digester project at Haubenschild Farms were originally brought to the attention of several Minnesota governmental agencies with the help of the Onanegozie Resource Conservation and Development Council and The Minnesota Project.
	www.bae.umn.edu /extens/ennotes/enspr01/fuel.htm (1134 words)

	Farming for Energy:Anaerobic Digesters -- Cow Power
		After three weeks in the digester, the manure — now a lot less smelly — empties into a storage lagoon for later application to the farm’s 1,000 acres of cropland.
		The University of Minnesota is conducting a three-year field study to compare the performance of digested manure with raw manure and commercial fertilizers.
		In fact, small anaerobic digesters have been used in China and India for decades, and more than 450 farm digesters generate fuel in Europe.
	www.auri.org /news/ainjul01/05page.htm (937 words)

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