Production of biogas with pretreatment of lignocellulose using organic solvent and hot water

Anaerobna digestija je mikrobiološki proces brez prisotnosti kisika pri katerem mikroorganizmi razkrajajo organske snovi in nastajata bioplin in presnovljen digestat. Bioplin in druga biogoriva je mogoče proizvesti iz različnih lignoceluloznih materialov, katerih struktura pa sicer lahko zavirujoče vpliva na delovanje procesa. S primernim postopkom predobdelave dosežemo spremembo strukture lignocelulozne biomase in izboljšanje delovanja anaerobnih mikroorganizmov. Namen diplomske naloge je bil ugotoviti kako predobdelava lignoceluloznih materialov vpliva na donos bioplina. Kot lignocelulozne materiale smo uporabili koruzno silažo in koruzno slamo. Dobljene kumulativne prostornine bioplina smo nato primerjali z rezultati, ki smo jih dobili pri paralelkah, katerih nismo predhodno obdelali. Za postopek predobdelave smo uporabili kemijsko predobdelavo z organskim topilom, fizikalno-kemijsko z vročo destilirano vodo ter kombinirano dvostopenjsko predobdelavo z organskim topilom v prvi stopnji in vročo vodo v drugi stopnji. Kemijsko predobdelavo smo izvedli z etanolom s Soxhletovim ekstraktorjem, pri fizikalno-kemijski predobdelavi pa smo uporabili vročo destilirano vodo in lignocelulozni material s kuhanjem izpostavili visokim temperaturam. Izkazalo se je, da se je z vidika prostornine bioplina najboljše izkazala nastavitev kombinirane predobdelave, kjer smo predobdelali koruzno silažo. V tej nastavitvi je nastalo skupno povprečno 582 mL bioplina na gram suhe snovi. Med omenjenim mikrobiološkim procesom smo analizirali tudi pH vrednosti, saj je zelo pomemben dejavnik, ki v primeru, da ne dosega ali preseže optimalno območje, ki je med 6,5 in 8, lahko moteče vpliva na delovanje procesa. V presnovljenem digestatu smo preverili še deleže Klasonovih komponent in ugotovili, da med paralelkami glede na predobdelavo v deležih ni večjih razlik.Anaerobic digestion is a microbiological process without the presence of oxygen in which microorganisms decompose organic matter and produce biogas and digested substrate. Biogas and other biofuels can be produced from a variety of lignocellulosic materials, but their structure may have an inhibiting effect on the functioning of the process. Using an appropriate pretreatment process, we can achieve a change in the structure of lignocellulosic biomass and improve the performance of anaerobic microorganisms. The purpose of the thesis was to determine how pretreatment of lignocellulosic materials affects the yield of biogas. Corn silage and corn stover were used as lignocellulosic materials. The obtained cumulative volumes of biogas were then compared with the results obtained for parallels without pretreated lignocelulosic materials. For the pretreatment process, chemical pretreatment with organic solvent, physicochemical with hot distilled water and combined two-stage pretreatment with an organic solvent in the first stage and hot water in the second stage was used. Chemical pretreatment was carried out using ethanol with Soxhlet extractor, and in physicochemical pretreatment hot distilled water was used and lignocellulosic material was exposed to high temperatures by cooking. The results from the viewpoint of biogas volume showed that the optimal pretreatment was combined one with pretreated corn silage. For this sample, a total of 582 mL of biogas in average was produced per gram of dry mass. During this microbiological process, pH values were also analyzed, as pH is a very important factor which, in the event that it does not reach or exceeds an optimal range between 6.5 and 8, it can interfere with the operation of the process. In the digestate the proportions of the Klason components were also analysed and it was found that there are no major differences between the parallels in terms of pretreatment in the proportions