reference should be had to fig1 and 2 which include legends which correspond to the description below . the following steps may be taken in any order plausible and steps may be omitted and still conform to the invention . cellulosic biomass is charged into a batch or continuous extraction reactor vessel and steam is added to heat the biomass at a pressure of 5 - 30 atmospheres for a duration of 2 minutes or more to obtain 10 - 30 % yield of dissolved solids comprised mostly of hemicelluloses and lignin . this extraction process is termed steam explosion . the reaction is catalyzed by formation of acetic acid from the cellulosic biomass . additional catalyst , such as acetic acid or a mineral acid or sulfur dioxide may be used to increase the dissolved solids fraction or to speed the extraction process . following extraction by steam explosion , the heated biomass is washed with water , and / or recirculated wash filtrate , and drained to recover the majority of the dissolved cellulosic biomass components . the wash filtrate , termed extract , contains dissolved xylan , glucan , mannan , arbinan , galactan and acetyl groups in oligomeric form of hemicelluloses as well as lignin . the extract has a low organic solids concentration of 1 %- 12 % by weight . the majority of the water in the extract must be removed before an economic treatment of hemicelluloses is possible . the remaining solid biomass is dewatered to approximately the same moisture content that it was when fed to the extraction reactor , typically 40 %- 60 % solids , by pressing it to approximately 30 atmospheres or more mechanical pressure through a commercial plug screw feeder , other pressing device , or other thermal / mechanical dewatering device . the host facility therefore experiences little or no change in the moisture content of its biomass feedstock available to be fed to the existing equipment for thermal conversion to energy . evaporation is used to concentrate the low solids extract from the second step , in - reactor washing , from 1 - 5 % solids to around 25 % or more . this concentration is preferably performed using a mechanical vapor recompression evaporator which is suitable because the boiling point rise of the extract is small . evaporated vapor is compressed , and condensed in the hot side of the evaporator to produce an almost equivalent amount of evaporation . if the extract feed concentration is over 5 % solids , this step may be omitted . when the ph of this step is kept below the acetic acid dissociation point of ph 4 . 8 , acetic acid in the extract , a fermentation inhibitor , is volatilized to the vapor fraction . concentrated extract from the low solids evaporation is hydrolyzed using sulfuric acid , heat or enzymes . oligomer hemicelluloses in the concentrated extract are converted into monomer sugars and acetyl groups are released . the hydrolyzate resulting from the hydrolysis is controlled to ph 3 - 4 . 8 to maintain acetic acid in unassociated form . hydrolyzate from hydrolysis is concentrated up to 50 % solids by evaporation , preferably using a mechanical vapor recompression evaporator . more of the remaining acetic acid and water is evaporated in this step . under the appropriate economic criteria , this step could be done with steam evaporation . sugars in the concentrated hydrolyzate are fermented in a continuous or batch fermentation tanks with one or more micro - organisms capable of converting five and six carbon sugars into alcohol and carbon dioxide . the majority of acetic acid , which may inhibit fermentation , was removed in the previous evaporation step . some additional acetic acid may be formed during fermentation . nutrients and ph adjustment chemicals as well as make - up fermentative organism are added in this fermentation step as and if needed . carbon dioxide is removed from the fermenters and scrubbed with cool water for alcohol recovery . this purified gas can be further compressed and sold as industrial grade carbon dioxide . the fermentation broth , commonly termed “ beer ”, from the fermentation step is sent to a distillation column . the beer from the fermentation step is sent to a beer distillation column to separate the alcohol from the solids and residual sugars . alcohol leaving as the overhead from the distillation column is recovered at approximately 30 - 50 mass -% strength . the final concentration of the alcohol product is performed in a rectifying column and drying system , preferably a molecular sieve , to obtain over 99 - mass % alcohol . the ninth step of the process is the solids concentration from the stillage . the solids , commonly termed “ stillage ”, from the beer distillation column bottom can be further evaporated in an optional concentrator , preferably a mechanical vapor recompression concentrator to achieve zero - liquid discharge operation . the dewatered biomass from the third step and the concentrated stillage from the ninth step are fed to the host facility existing equipment for thermal conversion to energy the eleventh step of the process is the integration of the biorefinery with the existing host facility . the physical plant combining the process steps as a whole or in part to produce alcohol and other chemical bioproducts is termed “ biorefinery ”. an energy integration analysis of the proposed biorefinery process indicates that utilizing mechanical vapor recompression evaporators achieves the minimum need for cooling water . the waste heat generated in the process is absorbed into the evaporator and column condensate streams , which can be utilized in the host facility to minimize overall steam and water consumption , and is preferably used for steam generator feedwater heating . in the second embodiment related to enzymatic conversion of cellulosic fiber to glucose and other monomeric sugars , the detailed description is as follows . reference should be had to fig3 which include legends which correspond to the description below . the first step of the process is the pulp mixing at 3 - 10 % consistency , using a low dosage of enzymes . the cellulose fiber feedstock , termed pulp , is prepared by chemical pulping of wood chips in acidic or alkaline conditions and may be partially bleached to have residual lignin content below 3 % by weight of the feedstock . the pulp at a consistency of 3 %- 10 % solids is mixed with an enzyme formulation which is preferably at less than 3 % by weight in proportion to cellulose and hemicellulose content of the delignified pulp . mechanical mixing is performed to promote enzymes contacting the cellulose fibers . mixing tanks in existing pulp and paper mills include broke and stock pulpers these are among the existing equipment and vessels that can be redeployed for this purpose . the second step of the process is the retention of pulp suspension , while maintaining moderate mixing . following step 1 , retention time must be provided to achieve the desired enzyme reaction on the pulp stock to produce a partially hydrolyzed pulp suspension . retention tanks in existing pulp and paper mills include high density storage , low density storage , machine chests , bleach towers , and broke surge tanks ; these are the among the existing equipment and vessels that can be redeployed for this purpose . the third step of the process is an addition of a small amount of enzymes . on reaching 25 - 50 % dissolution of sugars , as measured by pulp weight loss , the partially hydrolyzed pulp suspension from the second step may be dewatered back to 3 - 10 % consistency , without significant loss of adsorbed enzymes . dissolved sugars in the filtrate are removed to reduce enzymatic inhibition . filtrate from subsequent steps may also be used to wash the pulp in the dewatering process . a small amount of enzyme formulation used in the first step is then added to the dewatered pulp suspension to maintain hydrolysis activity during the extended period . new pulp from the first step is also added as needed to maintain optimum consistency for mixing and enzymatic activity . dewatering devices in existing pulp and paper mills include side hill screens , stock washers , savealls , fourdrinier wire sections and press sections of pulp and paper machines ; these are the among the existing equipment and vessels that can be redeployed for this purpose . the second and third steps may be repeated one or more times to achieve complete hydrolysis . the final step of the process is to remove unhydrolyzed solids , consisting mainly lignin in the pulp feedstock . the lignin is filtered from the sugar solution . the filter cake may be washed and pressed to minimize the sugar content . the lignin filtering devices in existing pulp and paper mills include stock washers , screw presses , fourdrinier wire sections and press sections of pulp and paper machines ; these are among the existing equipment and vessels that can be redeployed for this purpose . 5 grams of o . d . pine pulp at 18 . 5 % consistency from alcohol sulfite process was dissolved with deionized water to 100 ml of pulp suspension . 250 ml erlenmeyer flasks were used . enzyme stock solution was prepared in 50 mm acetate buffer ( ph 5 . 02 ). final volume was made up to 100 ml with deionized water . 100 mg of novozymes ctec / htec enzymes were added at [ 8 : 1 ] ratio . enzymatic reaction was incubated on a water bath at 50 ° c . and mixed at 200 rpm . after the first 36 hour retention period , 25 mg of enzyme formulation was added . the hydrolysis was allowed to proceed another 36 hours , at which point another 25 mg of enzyme was added . the procedure resulted 84 . 7 % weight loss . in comparison , the hydrolysis of same pulp with the same 150 mg enzyme dosage in one step resulted 84 % weight loss . 5 grams of o . d . pine pulp at 18 . 5 % consistency from alcohol sulfite process was dissolved with deionized water to 100 ml of pulp suspension . 250 ml erlenmeyer flasks were used . enzyme stock solution was prepared in 50 mm acetate buffer ( ph 5 . 02 ). final volume was made up to 100 ml with deionized water . 50 mg of novozymes ctec / htec enzymes were added at [ 8 : 1 ] ratio . enzymatic reaction was incubated on a water bath at 50 ° c . and mixed at 200 rpm . after 36 hours , 50 mg of enzyme formulation was added . the hydrolysis was allowed to proceed another 36 hours , at which point another 50 mg of enzyme was added . the procedure resulted to 75 . 7 % weight loss . in comparison , the hydrolysis of same pulp with the same 150 mg enzyme dosage in one step resulted 84 % weight loss . 5 grams of o . d . pine pulp at 18 . 5 % consistency from alcohol sulfite process was dissolved with deionized water to 100 ml of pulp suspension . 250 ml erlenmeyer flasks were used . enzyme stock solution was prepared in 50 mm acetate buffer ( ph 5 . 02 ). final volume was made up to 100 ml with deionized water . 100 mg of novozymes ctec / htec enzymes were added at [ 8 : 1 ] ratio . enzymatic reaction was incubated on a water bath at 50 ° c . and mixed at 200 rpm for 12 hours . the suspension was dewatered to 10 % consistency . the hydrolysis proceeded to approximately 32 % weight loss in 24 hours . a fresh buffer and 25 mg of enzyme formulation was added to 5 % consistency . the hydrolysis was allowed to proceed another 12 hours , at which point the consistency was increased to 10 % for 24 hours . the hydrolysis proceeded to approximately 47 % weight loss , at which point fresh buffer and 25 mg of enzyme formulation was added to 5 % consistency . the hydrolysis was allowed to proceed another 12 hours , at which point the consistency was increased to 10 % for 24 hours . the procedure resulted to 84 . 8 % weight loss . in comparison , the hydrolysis of same pulp with the same 150 mg enzyme dosage in on step resulted 84 % weight loss .