5 results
Now showing1 - 5 of 5
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Reductive catalytic fractionation of straw digestates for the production of biogenic aromatic monomers(Elsevier, 2024-04-01); ; ; ; Lignin is hardly degraded and presumably only scarcely structurally modified during the anaerobic digestion of straw and thus accumulating in the digestate remaining after digestion. As available industrial residue stream and due to the accumulation of unmodified lignin, such a digestate appears as promising substrate for the production of biogenic aromatics. One process for recovering monomeric aromatics from structurally unmodified lignin is the Reductive Catalytic Fractionation (RCF). Here, the RCF of straw digestates from a lab fermentation and from an industrial plant was investigated and compared to the RCF of unfermented straw as well as beech wood. It turned out that monomeric aromatics can be recovered from straw digestates by RCF. Removing impurities from the digestates by washing, increasing the hydrogen pressure and extending the reaction time to at least 7 h further increased the monomer yield. The selectivity towards γ-OH groups in the monomers can be controlled by the hydrogen pressure and the choice of hydrogenation catalyst. No yield-reducing influence of hydroxycinnamic acids found in straw got evident, however, only their purely ester-bound fraction could be easily removed and quantified. Compared to the straw digestates, monomer yields on biomass basis were lower from unfermented straw, but significantly higher from beech wood for all tested catalysts. Thus, although having a comparable lignin content, beech wood represents a higher yielding source for monomeric biogenic aromatics compared to straw digestates.Publicationtype: Journal Article38 100 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Fractionation of lignocellulosic fibrous straw digestate by combined hydrothermal and enzymatic treatment(Multidisciplinary Digital Publishing Institute (MDPI), 2022-08-23); ; ; ; In industrial-scale biogas production from cereal straw, large quantities of solid fiber-rich digestate are produced as residual material. These residues usually contain high amounts of cellulose, hemicellulose and lignin and thus have potential for further utilization. However, they also contain impurities such as ammonia and minerals, which could negatively affect further utilization. Against this background, the present study investigates how this fibrous straw digestate can be fractionated by a combined hydrothermal and enzymatic treatment and what influence the impurities have in this process. Therefore, it is analyzed how the fractions cellulose, hemicellulose and lignin are modified by this two-stage treatment, using either raw digestate (including all impurities) or washed digestate (containing only purified fibers) as the substrate. For both substrates, around 50% of the hemicellulose is solubilized to xylans after 50 min of hydrothermal treatment using steam at 180 °C. Furthermore, by subsequent enzymatic treatment, around 90% and 92% of the cellulose and hemicellulose still contained in the solids are hydrolyzed to glucose and xylose, respectively. Lignin accumulates in the remaining solid but structurally degrades during the hydrothermal treatment, which is indicated by decreasing ether and ester bond contents with increasing treatment times. Impurities contained within the raw digestate do not hinder this fractionation; they even seem to positively affect hemicellulose and cellulose valorization, but apparently lead to a slightly higher lignin degradation.Publicationtype: Journal ArticleScopus© Citations 4 117 149 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Biogas production from straw—the challenge feedstock pretreatmentStraw fermentation offers the advantage to provide energy for the electricity, the heat, and/or the mobility sector, while contributing in parallel to close nutrient and humus cycles in agriculture. In this study, the state of technology of straw biogas fermentation is assessed. The results show that the selection of an adequate pretreatment process is one of the main key factors for a successful provision of biogas from straw. The subsequent assessment of three pretreatment options (i.e., mechanical treatment, steam explosion, alkaline treatment) shows that a mechanical pretreatment is economically more viable than the other options, even though the expected biogas yield is clearly lower. This is mainly because chemical or thermal pretreatment results in high investment cost due to high pressure or long residence times. [Figure not available: see fulltext.]Publicationtype: Journal Article194 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Protein recovery from bioethanol stillage by liquid hot water treatment(2020-01); ; Protein recovery from biogenic residues offers a high potential for increasing the added value. This paper investigates the protein recovery from bioethanol stillage by liquid hot water treatment at pH 3–11 and 110–210 °C for 10–90 min. The results show that protein solubilization starts at 89 °C and is limited by temperature. However, all amino acids except glutamic acid start to degrade at 170 °C. Especially lysine, arginine and asparagine undergo Maillard reactions, whereby degradation is favoured by bases; acids show a stabilizing effect. The highest protein yield in the hydrolysate is 75% with a concentration of 53%-DM at 170 °C and 20 min. In addition, kinetic modelling of the rate constants for protein solubilization and amino acid degradation is performed. Rate constants for amino acid degradation are about one order of magnitude higher for polar than for non-polar amino acids.Publicationtype: Journal Article282 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Improved HPLC-method for estimation and correction of amino acid losses during hydrolysis of unknown samples(2018-02-15); ; Amino acid analysis, commonly done by acid hydrolysis of proteins and HPLC analysis, faces one major problem: incomplete hydrolysis of stable amino acids and degradation of unstable amino acids are causing amino acid losses. As a result, amino acid recovery of unknown samples cannot be estimated. Some methods have been reported for correction of these factors in the past. This paper shows an improved and integrated method to overcome this problem by using stillage as an exemplary unknown sample material. Amino acid recovery from an unknown sample can be estimated by standard addition of a known protein. If the sample does not cause matrix effects during amino acid hydrolysis, recoveries of the standard protein are transferable to the sample. If the sample does cause matrix effects correction of amino acid losses can instead be done by determination of hydrolysis kinetics. Therefore, first order kinetics were used for amino acids that undergo degradation during hydrolysis. For all stable amino acids higher order kinetics were used, a novel approach to determine hydrolysis kinetics. The presented method can be a helpful tool for scientists who want to optimize amino acid analysis of a particular biomass substrate.Publicationtype: Journal Article150