Production Of Bioethanol From Brewery Spent Grain Using Cellulase Enzyme Hydrolysis

Bioethanol is a clear, colorless and mobile flammable liquid chemical compound with acceptablernodour, and produced from biomass feed stocks through fermentation. The objective of this studyrnwas production of bioethanol from Barley spent grain by using cellulase enzyme hydrolysis.rnDecreasing of world petroleum reserves, fluctuation of petroleum price and environmentalrnconcerns, low yield cellulose acid hydrolysis and formation of inhibitory were the problemrnstatement. Enzymatic hydrolysis method was used for cellulose hydrolysis, producing monomericrnC6 sugars (glucose); enzymatic hydrolysis is more specific and high conversion rates can bernachieved in long reaction times obtaining very high yields. Raw material characterization of BSGrnwere, hemicelluloses content 28.4 %, cellulose content 27 %, and dry matter content 98.2 %. Thernaim of pretreatment is to disrupt recalcitrant structures of cellulosic biomass to make cellulosernmore accessible to the enzymes that convert carbohydrate polymers into fermentable sugars. Thernpretreated feedstock was mixed with 1.25 % (v/v) sulfuric acid solutions with a liquid-to-solid ratiornof 20 %( w/w) and it was occurred on the temperature 121 ºC and time of 17 min, the severityrnfactor coefficient was 0.198. Cellulase enzyme was produced from BSG using bacillus subtilus,rnunder liquid state fermentation for 5 days at temperature of 37 ºCrnwith pH of 5.0, in controlledrnincubator. For the enzyme hydrolysis, 26 full factorial central composite design (CCD) wasrnapplied to investigate the effect of temperature (40-50 ºC), pH (4.0-5.0), reaction time (24-72 hr.)rnand enzyme loading (1-2 %) using Design expert® 6 software. RSM was applied to investigate therninteraction effect of hydrolysis process variables on the yield of ethanol from BSG. After hydrolysisrnprocess sugar content of the hydrolysate was quantified using spectrophotometer measuring itsrnabsorbance. Fermentation of the hydrolysate were performed 2.5 % Saccharomyces cerevisiaernand 2.5 % fusarium oxysporum at 30 ºC temperature, pH 5.0 and 72 hr. fermentation time for allrnsamples. Significance of the process variables were analyzed using analysis of variance. As thernresult of RSM optimization, the best yield of TRS was found at 40 ºC hydrolysis temperature, 4.5rnPH, 48 hr. reaction time and 1.5 % v/v enzyme loading. Under these condition 96.55 %w/w andrn53.68 % per 6.58 g dry barley spent grain of TRS and bio-ethanol respectively obtained.

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