پيش فرآوري شيميايي مواد لينگوسلولزي به منظور بهبود توليد بيوگاز به روش تخميرفاز جامد

چكيده انگليسي :

Enhancement of dry biogas production by chemical pretreatment of lignocellulosic materials Safoora Mirmohamadsadeghi safoora mirmohamadsadeghi@ce iut ac ir Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree PhD language FarsiDr Keikhosro Karimi karimi@cc iut ac irAbstractUsing anaerobic digestion AD for biogas production has several environmental advantages AD is divided intowet digestion total solid 15 and solid state digestion total solid 15 Solid state anaerobic digestion SSAD is preferred to wet digestion especially for lignocellulosic feedstocks due to their low moisture content However digestion of lignocelluloses is limited due to their recalcitrance structure and low hydrolysis rate Therefore using a pretreatment method seems necessary to improve lignocelluloses digestibility The purpose ofthis dissertation was improvement of SSAD performance using pretreatment methods The effects of sixpretreatment methods i e phosphoric acid sulfuric acid sodium hydroxide ammonia solution sodiumcarbonate and organosolv on SSAD of lignocelluloses were studied After that three methods i e phosphoricacid organosolv and sodium carbonate were chosen for more investigation Also the idea of using rice strawdigestate to produce nanosilica were proposed and investigated The effect of organosolv pretreatment on methaneyield from SSAD of lignocellulosic substrate was studied The pretreatment was carried out using ethanol as anorganic solvent together with sulfuric acid as a catalyst at 150 and 180 C for 30 and 60 min Statistical analysisshowed that the pretreatment temperature was the most important factor affecting methane production Afterpretreating lignocelluloses at the optimum temperature the highest methane yields were about 153 94 and 71liters per kg of carbohydrate in rice straw elmwood and pinewood respectively which showed 32 73 and 84 enhancement in comparison with the untreated ones A reverse relation between methane yield and lignin contentwas observed The kinetic data of all untreated and pretreated samples were fitted on first order kinetic model Phosphoric acid pretreatment COSLIF has been repeatedly shown to be a cost effective and promising processto modify the structure of different lignocelluloses Improvement of solid state biogas production fromlignocelluloses using concentrated phosphoric acid pretreatment was studied Feed to inoculum F I ratio whichplays a major role in SSAD was set to 3 4 and 5 After the pretreatment 24 to 39 higher methane yield frompine was achieved Considerable reduction in hemicellulose and lignin content reduction in cellulose crystallinity and increase in accessible surface area were the changes observed after the pretreatment Mild sodium carbonate pretreatment as a modern and promising method were also studied The results showedthat sodium carbonate pretreatment markedly enhanced the sugar yields from enzymatic hydrolysis of thelignocellulosic biomass The glucose yields from enzymatic hydrolysis were increased up to 62 to 96 2 to 4fold higher than that of untreated feedstocks and the xylose yields were improved up to 69 77 5 to 20 foldmore than that of untreated feedstocks The most important effect of the pretreatment was lignin removal whilethe amounts of glucan and xylan degradation were low Using ultrasonic with sodium carbonate could onlyincrease xylose yield Finally the rice straw residue from SSAD was applied for silica preparation SSAD wasused instead of direct burning of rice straw which is the common methods for silica production By convertingorganic fraction of rice straw into biogas while generating solid digestate rich in silica the economy of the processcan be improved The methane yield obtained from dry digestion was 119 L kg volatile solid of the substrate Silica content in the digestate ash was 21 more than that in the ash of raw rice straw Nano particles withdiameter between 15 to 30 nm were obtained KeywordsBiogas Lignocellulosic f

ميرمحمدصادقي، صفورا

پيش فرآوري شيميايي مواد لينگوسلولزي به منظور بهبود توليد بيوگاز به روش تخميرفاز جامد

هضم بي هوازي , باقيمانده هضم , سيليكا