Effect Of Pretreatments On Wheat Straw Saccharification And Biogas Fermentation

China is a major wheat-producing country, and has abundant resources of wheat stalkwith annual production of about700million tons. Biogas fermentation of wheat stalk is oneof the effective ways to use these resources as well as alleviate the energy crisis and reducethe environmental pollution caused by burning stalks. This paper mainly investigated theeffect of different pretreatments on wheat straw saccharification and efficiency of biogasfermentation. The results are listed as follows:1. Soaking pretreatment with water, saturated lime water and urea solution enhancedsugar yield of wheat straw by enzymatic hydrolysis. Comparing to the control treatment, theenzymatic hydrolysis sugar yield of wheat straw soaked by urea solution increased from130.5%to146.1%, the saturated lime water treatment increased from49.3%to79.2%, thewater treatment increased from27.3%to52.8%. Urea solution soaking wheat straw'soptimum temperature was at40℃, favorable immersion time was three days, and theoptimum concentration is20g·L^-1.2. The cellulase increased the reducing sugar content of wheat straw. Along with theincrease of cellulase addition amount, the reducing sugar yield of wheat straw increased from96.4%to199.8%compared with the control.3. Both bacteria or fungi inoculation alone and combination inoculation with bacteriaand fungi increased reducing sugar content in the fermentation broth and the enzymatichydrolysis sugar yield of wheat straw.①The bacteria inoculation pretreated straw did notaffect the reducing sugar content in fermentation broth.②The fungi A8inoculation pretreatedstraw did not increase the reducing sugar content in fermentation broth. The reducing sugarcontent in fermentation broth of pretreated straw inoculated with fungi Z27increased by44.0%compared with the control.③The total sugar yield was higher inoculated withbacteria and fungi compared to the individual bacteria or fungi inoculation. The total sugaryield inoculated with bacteria NH₀711, N₀H513, N₀H₀511and N₀H514combined with fungiA8treatment were increased by11.9%,28.3%,9.7%and5.9%compared with A8individualinoculation, respectively. The total sugar yield inoculated with bacteria NH₀711, N₀H513,N₀H₀511and N₀H514combined with fungi Z27treatment were increased by16.8%,48.7%,61.6%and40.4%compared with NH₀711, N₀H513, N₀H₀511and N₀H514individual inoculation, respectively.4. Adding available nutrient improved the enzymatic hydrolysis sugar yield of straw. Inthe solid-state fermentation of straw unamended with exogenous nutrition, the growth ofmicroorganisms was slower, cellulase produced less, and resulted in the reduction of sugarcontent in the solid-state fermentation as well as the enzymatic hydrolysis sugar yield offermented straw. Soluble starch and chicken manure amended improved the nutritionalcondition of fermentation matrix, promoted cellulase producing microbes' growth, raisedcellulase activity and the enzymatic hydrolysis sugar yield of straw.5. Soaking treatment with urea solution increased biogas production and methaneproduction during the biogas fermentation with straw.①In normal condition, theaccumulative biogas yield of urea solution soaked straw treatment increased by6.8%compared with water soaked control treatment. In the fermentation condition, theaccumulative biogas yield of urea solution soaked straw treatment increased by21.7%compared with water soaked control treatment.②Urea solution soaking pretreated strawincreased methane production in the biogas fermentation compared with the control treatment.In normal condition, the accumulative methane yield of urea solution soaked straw treatmentincreased by10.9%compared with water soaked control treatment. In the fermentationcondition, the accumulative methane yield of urea solution soaked straw treatment wasincreased25.0%compared with water soaked control treatment.