The use of lignocellulosic cosubstrates for production of biogas

Namen diplomske naloge je poiskati način, kako bi lahko izboljšali pridobivanje bioplina in obenem nekoliko zmanjšali pritisk, ki ga le-ta prinaša na prehrambno verigo. Ugotavljali smo, če bi z zamenjavo koruzne silaže z drugimi energetskimi rastlinami, kot je npr. koruzna slama, proizvedli podobno količino bioplina in kakšen bi bil ekonomski učinek zamenjave silaže s slamo. Raziskavo smo izvedli z večjim številom paralelk v treh ponovitvah in v različnih razmerjih gnoja z nastiljem in koruzne slame oz. silaže, kjer smo koruzno silažo popolnoma zamenjali s koruzno slamo, silažo le delno zamenjali s slamo ter nastavitev, v kateri smo uporabili izključno piščančji gnoj z nastiljem brez dodatka sosubstratov slame in/sli silaže. Kot začetno predpostavko, s katero smo na koncu primerjali dobljene rezultate, so nam služili podatki obstoječe bioplinarne, ki za svojo proizvodnjo uporablja gnoj z nastiljem in koruzno silažo. Da pa bi ustvarili kar se da podobne pogoje kot jih imajo v bioplinarni, smo v vseh nastavitvah uporabljali inokulum, kakršnega uporabljajo v bioplinarni Draženci. Med samim procesom anaerobne digestije smo nato merili količino sproščenega bioplina in merili množinski delež metana in CO2 ter razgradnjo substratov. Dobljene rezultate smo ekstrapolirali na industrijsko merilo in izvedli primerjalno ekonomsko analizo stroškov uporabe vhodnih surovin. Tako iz vidika proizvodnje bioplina kot tudi iz ekonomskega vidika smo dobili obetajoče rezultate. Opazili smo, da že delna zamenjava silaže s tržno cenejšo koruzno slamo prinese znatne izboljšave ne samo iz vidika proizvedene količine bioplina, ampak tudi iz vidika stroškov surovin.The purpose of this diploma thesis is to find a way as how to improve the production of biogas and at the same time to reduce the amounts of corn silage, which brings a pressure to the food chain. We investigated if the replacement of corn silage with other energy crops, such as corn stover, would produce similar amounts of biogas, and what would be the economic effect of replacing corn silage. The study was carried out with a higher number of parallels in three repetitions and in different proportions of poultry manure with beddings and corn silage or stover. The experiments were conducted where corn silage was completely replaced with corn stover, silage was only partly replaced with corn stover, and also where only poultry manure with beddings was used without the addition of co-substrates. As an initial assumption, with which we compared the obtained results, we used the data from the existing biogas plant, which also uses maize silage for its production. In order to create the conditions as close as possible to those in the biogas plant Draženci, we used their inoculum in all the experiments. During the process of anaerobic digestion, we measured the amounts of produced biogas, the quantity of methane and carbon dioxide (CO2), and the quantity of produced digestate. We extrapolated the given results to the industrial level and performed a comparative economic analysis of the raw material costs. From both, amounts of produced biogas and from economic perspective, we have obtained promising results. We have noticed that even partial replacement of silage with cheaper corn stover results in significant improvements, not only in terms of higher yield of produced biogas, but also from the viewpoint of raw material cost