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In this study modeled full scale application of thermobarical hydrolysis of less degradable feedstock for biomethanation was assessed in terms of energy balance, greenhouse gas emissions, and economy. Data were provided whether the substitution of maize silage as feedstock for biogas production by pretreated cattle wastes is beneficial in full-scale application or not. A model device for thermobarical treatment has been suggested for and theoretically integrated in a biogas plant. The assessment considered the replacement of maize silage as feedstock with liquid and/or solid cattle waste (feces, litter, and feed residues from animal husbandry of high-performance dairy cattle, dry cows, and heifers). The integration of thermobarical pretreatment is beneficial for raw material with high contents of organic dry matter and ligno-cellulose: Solid cattle waste revealed very short payback times, e.g. 9 months for energy, 3 months for greenhouse gases, and 3 years 3 months for economic amortization, whereas, in contrast, liquid cattle waste did not perform positive replacement effects in this analysis.

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"This is an Accepted Manuscript of an article published by Taylor & Francis in Biofuels on 03/08/2015, available online: http://wwww.tandfonline.com/10.1080/17597269.2015.1065589Efficient utilization of lignocellulosic biomass requires pretreatment in order to liberate cellulose from lignin and disrupt its recalcitrant crystalline structure before effective enzymatic hydrolysis can take place. Three different pretreatment methods (pressure cooking with dilute alkali and dilute acid as well as alkaline extraction) to recover the xylooligosaccharides fraction from five different grass silage samples, whole crop rye silage and maize silage were compared. The predominant end products released were xylobiose, xylotetraose, xylopentaose and xylohexaose whereas the xylooligosaccharides release pattern differed with the substrate. Maximum values of xylooligosaccharides was found for grass silage 17.26 g/L, whole crop rye silage 3.06 g/L and for maize silage 5.77 g/L. Results reveal the production of high value by-products from agricultural biomass. Advantages of the green-biorefinery concept include a resulting liquid fraction after pretreatment with very low contents of inhibitors such as furfural, hydroxymethylfurfural (HMF) and phenolic compounds. Document embargo 03/08/2016.authorsversionPeer reviewe

Continuous bio-methanization of different feedstocks (rye grain silage, maize silage, feed residue (mix of silages), solid cattle manure, and grass silage) was investigated in a long-term laboratory-scale experiment with and without enzyme application. Ten-liter reactors were operated simultaneously in a two-step digestion mode for the continuous production of biogas from different feedstocks over 354 days. One set of reactors was operated as main digester, while the second set was used for the second step. The daily input of feedstock was increased from an organic loading rate of 1 to 3 kg ODM 3 m À3 3 d À1 . All digesters were run under stable conditions, indicated by the ratio of volatile fatty acids to the total inorganic carbon, ranging around 0.2 in the first step and 0.15 in the second step. The hydraulic retention time was maintained between 80 and 90 days during the experiment. The application of enzymes was able to enhance biogas production by 10À15% and increase the methane content of biogas by an increment of 5À10% for the investigated materials except for feed residue. The increase in biogas yields was also reflected in the change in the ratios of heating values of the methane produced to the dry materials. These ratios ranged between 0.43 and 0.71 for the untreated feedstock, increasing to 0.44À0.88 after enzyme application.