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3. Sugar Separation <br />Approximately half nfthe energy value in the cellulosic feedstock is captured in the <br />sugars produced in hydrolysis. Fermentation will be more efficient if this is <br />separated from other compounds, especially lignin. This can be accomplished with <br />membranes. The lignin also contains about half of the energy and can be used as an <br />energy source for the process. <br />4. Fermentation <br />Once the cellulose has been broken into sugars, microorganisms are used toferment <br />the sugar and produce ethanol. Traditionally, baker's yeast has long been used in <br />the brewing industry to produce ethanol from hexoseo (6-carbon sugar). When <br />|ignooa||u|osic biomass io hydrolyzed to produce sugars, several sugars are produced <br />including ny|oaeand arab|nose[6-carbonsugars). As result, specially engineered <br />microorganisms, mainly yeasts, have been developed and utilized in fuel ethanol <br />production from cellulose. <br />S. Distillation <br />The liquid resulting from fermentation is separated from any solids and heated to <br />vo|aUze the ethyl alcohol which is then condensed. The process is repeated to <br />increase the ethanol concentration. An adsorption technique may be used toremove <br />the remaining water to produce anhydrous ethanol. <br />Because of the concern about using food crops to produce fuels and the potential <br />cost savings, e large number of companies have developed cellulosic ethanol <br />technologies, including: <br />° Abengoa 0oenergy <br />" AJioo <br />• B|ueRre Ethanol <br />• China Resources Alcohol Corporation [CRAC1 <br />° <br />Dyadic International, Inc. <br />° GneenFie|d Ethanol <br />� <br />Gulf Coast Energy <br />° IogenCorponation <br />* Masoorna <br />° POETB|onafinery <br />" <br />Range Fuels <br />� SunOpta Inc <br />* Vereniurn Corporation <br />° Xethano| <br />1.3.2 KBiogam <br />Roger Haug defines composting as "the biological decomposition and stabilization of <br />organic substrates, under conditions that allow development of thenmophi|io <br />temperatures as a result of biologically produced heat, to produce a final product <br />that isstable, free of pathogens and plant seeds, and can be beneficially applied to <br />land." 15 Composting of MSVV or a portion ofy4SVV such as yard waste is usually <br />carried out in the presence of air (aerobically) to produce a soil amendment and to <br />reduce the amount ofMSVV being deposited in landfills. When composting is done in <br />the absence of air (anaerobically), the biogas produced contains a significant amount <br />1sRogerT.Haug,ThaPractca|HandbookofCompostEnginaahng,LewisPubUshens,1993. <br />{]BB/C08027-01 8-17 August 15,2OO8 <br />