Optimization of biogas production from lignocellulosic cosubstrates

Zaradi onesnaževanja okolja se v zadnjem času vedno več uporabljajo obnovljivi viri energije med katere sodi tudi bioplin. Za proizvodnjo bioplina se v veliki količini kot ko-substrat uporablja koruzna silaža, kar pa je etično sporno, saj lahko koruza služi tudi kot vir hrane. Koruzno silažo smo zato poskušali nadomestiti z ostalimi substrati, predvsem s koruzno slamo. Pri eksperimentalnem delu smo kot glaven substrat uporabili inokulum iz bioplinarn Ihan in Draženci ter črno in slamnato piščančjo steljo iz bioplinarne Draženci, katerim smo dodali koruzno slamo. Za primerjavo nam je služil vzorec s celulozo, samim inokulumom ter vzorci s ko-substratom koruzno silažo. Med poskusom smo spremljali količino nastalega bioplina ter vsebnost metana in ogljikovega dioksida v bioplinu. Ko smo končali s poskusom, smo določili še stopnjo razgradnje materiala med procesom anaerobne digestije. Ugotovili smo, da je bilo v primeru, kjer smo uporabili inokulum iz bioplinarne Ihan, z dodatkom koruzne slame k slamnati stelji mogoče doseči enako proizvodnost bioplina kakor z dodatkom koruzne silaže. V primeru, ko pa smo uporabili inokulum iz bioplinarne Draženci, pa je bila z dodatkom koruzne slame proizvodnost nižja kakor z dodatkom koruzne silaže. Če primerjamo med sabo vzorce s slamnato steljo in vzorce s črno steljo, je bila proizvodnost bioplina v vseh primerih večja pri vzorcih s slamnato steljo. Deleži trdne snovi po končani anaerobni digestiji so v skladu s pričakovanji nižji pri vzorcih z večjo proizvodnostjo in obratno.Nowadays we are more and more using renewable sources of energy more and more, especially due to the pollution of the environment. Biogas is one of them, and maize silage is mostly used as a co-substrate for its production. However, using maize sillage for energy is unethical, as maize could also be used as a food source for people and animals. We have therefore tried to replace maize silage with other substrates, especially with maize straw. In the experimental part of this work we used inoculum from the biogas plants Ihan and Draženci, and black and straw-based poultry litters from the biogas plant Draženci as the main substrates, to which we added maize straw. We compared the biogas productivities of those substrates with the biogas productivities when using cellulose, pure inoculum and maize silage as a co-substrates. During the experiment we measured the amount of the biogas produced and the proportion of methane and carbon dioxide within the biogas. After finishing the process, we measured the materials’ decomposition levels during the process of anaerobic digestion. We discovered that when we used inoculum from Ihan and added maize straw to straw litter, the same production of biogas was obtained as when adding maize silage. When we used inoculum from Draženci and added maize straw, the production of biogas was lower than in those cases when adding maize silage. When comparing the samples with straw litter and samples with black litter, the production of biogas was always higher in samples with straw litter. The content of the dry solid matter after the anaerobic digestion was, as expected, lower in samples with higher biogas productivity and vice-versa