Production of biogas from brewers' spent grain

U današnje vrijeme sve je veći pritisak društva na smanjenje emisije ugljikovog dioksida u industrijskoj proizvodnji. U industriji piva kao i u ostalim prehrambenim industrijama nastoji se razviti održivo gospodarenje otpadom i otpadnim materijalima koji nastaju u proizvodnim procesima. Proizvodnja bioplina iz ostataka industrijskih procesa smatra se ekološki prihvatljivim i održivim procesom čija primjena rezultira značajnim smanjenjem uporabe fosilnih goriva što dovodi do smanjenja emisije ugljikova dioksida. Anaerobna digestija je biokemijski proces u kojem se organski materijali razgrađuju mikrobiološkim procesima bez prisutnosti kisika, pri čemu nastaje bioplin i čvrsti ostatak, digestat. Proces anaerobne razgradnje sastoji se od četiri procesne faze: hidroliza, acidogeneza, acetogeneza i metanogeneza. Industrijska proizvodnja piva ima za posljedicu nastajanje velike količine otpada pri čemu su najznačajnija tri otpadna toka: otpadna voda, otpadni kvasac i pivski trop. Otpadna voda se obrađuje klasičnim aerobnim biološkim metodama, a u novije vrijeme anaerobnom razgradnjom uz istovremenu proizvodnju bioplina. Otpadni kvasac, također se obrađuje anaerobnom obradom na način da se pomiješa s otpadnom vodom industrijske proizvodnje piva. Pivski trop je sporedni produkt proizvodnje piva koji nastaje u najvećoj količini i čini približno do 85 % ukupne mase sporednih produkata. Ima širok spektar upotrebe, a najčešće se upotrebljava za ishranu stoke. Tek se nedavno pivski trop počeo razmatrati kao supstrat za dobivanje energije, zbog sve većeg porasta cijena energije i povećane brige za očuvanjem okoliša.Nowadays there is an increasing social pressure to reduce emissions of carbon dioxide in industrial production. In the beer industry as well as in other food industries strives to develop sustainable management of waste and waste materials generated in production processes. The production of biogas from residues of industrial processes considered environmentally friendly and sustainable process whose application results in a significant reduction in the use of fossil fuels, which leads to a reduction in carbon dioxide emissions. Anaerobic digestion is a biochemical process during which complex organic matter is decomposed in absence of oxygen, by various types of anaerobic microorganisms, whereby biogas is formed and the solid digestate. The process of anaerobic digestion consists of four process steps: hydrolysis, acidogenesis, acetogenesis and methanogenesis. The industrial production of beer has resulted in a large amount of waste being the most significant three waste streams: wastewater, waste yeast and brewers' spent grain. Wastewater is treated conventional aerobic biological methods, and more recently anaerobic digestion, with simultaneous production of biogas. Waste yeast, are also treated in the anaerobic treatment method is that the wastewater is mixed with the industrial production of beer. The brewers' spent grain is a by-product of the beer produced in the largest quantities and makes about 85 % of the total weight of by-products. It has a wide range of use, but its main application has been limited to animal feeding. Only recently, brewers' spent grain began to consider as a substrate for energy, because of the increasing rise in energy prices and increased concern for the preservation of the environment