References of "Greger, Manfred 50001889"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailOptimisation of the Co-Digestion of Maize and Grass Silage Influence of the Substrate Mixture on the Biogas Yield
Benito Martin, Patricia Cristina UL; Sibisi-Beierlein, Nonjabulo N.; Greger, Manfred UL

in Bilitewski, B.; Clarke, W. P.; Cossu, R. (Eds.) et al Venice 2012 Fourth International Symposium on Energy from Biomass and Waste Proceedings (2012, November)

In recent years, energy crops have been increasingly introduced as co-substrates in biogas plants due to their high biogas yield potential. The purpose of the current research was to investigate the ... [more ▼]

In recent years, energy crops have been increasingly introduced as co-substrates in biogas plants due to their high biogas yield potential. The purpose of the current research was to investigate the influence of the mixture of maize and grass silages, added as feedstock, on the specific methane production (SMP) and on the process dynamics. To this end, biological methane potential (BMP) tests were carried out in 500ml reactors with grass and maize silage in mono-digestion and 3 different co-digestion mixtures. For selected mixtures, process dynamics were further investigated in batch anaerobic experiments in 1 litre reactors by measuring different control parameters. A positive correlation was observed between the proportion of grass in the mixture and the specific methane yield due to the higher protein content (a yield up to 6% higher in comparison with mono-digestion of maize). Nevertheless, increasing amounts of grass were also related with slower degradation (lower hydrolysis rate constants) and higher instability during the first days of digestion. [less ▲]

Detailed reference viewed: 152 (21 UL)
Full Text
Peer Reviewed
See detailMonitoring biodegradability of lignocellulosic biomass during anaerobic digestion
Benito Martin, Patricia Cristina UL; Sibisi-Beierlein, Nonjabulo N.; Greger, Manfred UL

in Book of abstracts of the 8th International Conference ORBIT2012 (2012, June)

Energy crops and crop residues can be digested anaerobically either alone or as co-substrate to produce biogas, a versatile renewable energy source. In the agricultural sector, this biomass is often co ... [more ▼]

Energy crops and crop residues can be digested anaerobically either alone or as co-substrate to produce biogas, a versatile renewable energy source. In the agricultural sector, this biomass is often co-digested with animal manure and slurry, one of the most significant agricultural waste streams. In spite of the growing number of agricultural biogas plants using agricultural waste and energy crops, the use of process simulation models for predicting and defining plant behaviour is still very limited, mainly due to the complexity of the process and the heterogeneity of the substrates. Also, the lack of standardized substrate characterisation methodology contributes to this issue. The chemical oxygen demand (COD), widely used as a mass balance term in modelling of wastewater treatment plants, could be applied in this field. However, COD is difficult to measure in the case of heterogeneous and solid substrates, including samples with high solids content. This, in turn, has limited its use to date to evaluate substrate biodegradability over time and methane production potential in the field of co-digestion of agricultural by-products. This research paper reports and analyses experimental results on the applicability of COD as a substrate characterisation and process monitoring parameter in the context of lignocellulosic biomass digestion, as collected from the research work currently being undertaken at the University of Luxembourg. The reliability of this parameter was investigated using different silages. Four sets of batch experiments were carried out using maize silage (12.17gVS/l), grass silage (14.58gVS/l), and two co-digestion mixtures of 40% maize and 60% grass (18.31 gVS/l) and 70% maize and 30% grass (12 gVS/l) in 1 litre reactors running under mesophilic conditions. The reactors were inoculated with pre-acclimatized inoculum from Beckerich agricultural biogas plant in Luxembourg. Soluble and particulate COD, volatile solids (VS), total solids (TS), volatile fatty acids (VFAs), and gas production, including composition, were monitored over a period of 24 days. A few adapted analytical procedures for measuring COD in solid and heterogeneous substrates and samples with high suspended solids concentration, in comparison to standard methods widely used for wastewater, have been proposed in recent years but these have rarely been applied and validated in the field of digestion of agricultural by-products. The COD methodology adopted in this study was developed by the process research group at the University of Luxembourg as a modification of the DIN 38414-S9 considering some suggestions from Raposo et al. (2008). The modified COD method was applied to different substrates (i.e. grass, maize silages, and cellulose) and also to monitor particulate COD (pCOD) evolution during anaerobic digestion of the different silages. The soluble COD (sCOD) method as established in the ISO 15705 standard method was modified for these experiments as the digestate has relatively high suspended solids concentration. First, the measured substrate COD concentration was compared with the theoretical oxygen demand for each substrate. COD recovery obtained was 96% for cellulose, 92.5% on average for the different maize silages tested and 91.5% on average for the grass silages tested. For all different batch series, the pCOD decreased overtime as a result of the hydrolysis of the particulate fraction of the substrate. The pCOD evolution along with the methane accumulative yield suggested that the solubilisation of the substrate was slower in the case of the co-digestion experiments. sCOD, on the other hand, initially increased sharply as a result of the solubilisation of the substrate and subsequent acidification and then decreased as digestion progressed. After 9 days of digestion, 77%, 71%, 69% and 48% substrate to methane conversion rates had been achieved for the experiments fed with grass silage, maize silage, the 70% maize/30% grass mixture and the 40% maize/60% grass mixture, respectively. Measuring the pCOD and sCOD together with biogas and VFAs concentration during digestion allows, not only to estimate the degradation advancement through COD mass balance, but also to obtain relevant information about the solubilisation of the particulate fraction (hydrolysis step). [less ▲]

Detailed reference viewed: 222 (12 UL)
Full Text
Peer Reviewed
See detailMonovergärung von Maissillage und Zellulose
Golkowska, Katarzyna UL; Greger, Manfred UL

in Cahiers scientifiques (2012), Vol. 1

Detailed reference viewed: 62 (5 UL)
Full Text
Peer Reviewed
See detailKinetic Considerations on Thermophilic Digestion of Maize Silage at Different Feeding Modes
Golkowska, Katarzyna UL; Sibisi-Beierlein, Nonjabulo; Greger, Manfred UL

in Chemie Ingenieur Technik (2012), 84(9),

Digestion of maize silage in batch, semi-batch and continuous mode was investigated under similar experimental conditions with the aim to compare the degradation kinetics. The modeling with the 1st order ... [more ▼]

Digestion of maize silage in batch, semi-batch and continuous mode was investigated under similar experimental conditions with the aim to compare the degradation kinetics. The modeling with the 1st order equation shows that despite the ensiling pre-treatment the disintegration/hydrolysis step determines the total degradation rate of the substrate. The results confirmed an extremely high adatation capability of anaerobic biocenosis to increased feeding frequency, rather than to higher but less frequent loadings. 2-3 times higher degradation rates were observed for triple feeding frequency. On the other hand an increase in organic loading within the same feeding mode always resulted in reduction of digestion rate. [less ▲]

Detailed reference viewed: 99 (3 UL)
Full Text
Peer Reviewed
See detailMonovergärung von Maissilage und Zellulose
Golkowska, Katarzyna; Greger, Manfred UL

in Cahiers scientifiques (2012), (1), 24-27

Detailed reference viewed: 46 (1 UL)
Full Text
Peer Reviewed
See detailStudying Microbial Dynamics in Anaerobic Monofermentation of Energy Crops – is FISH the right Technique
Beierlein-Sibisi, N. UL; Greger, Manfred UL

in Microbes in Wastewater and waste Treatment, Bioremediation, and Energy Production (2011)

Detailed reference viewed: 41 (1 UL)
Full Text
Peer Reviewed
See detailInfluence of environmental conditions for the rheological properties of SCC
Weisheit, Sandro UL; Waldmann, Danièle UL; Greger, Manfred UL

in Professeur D. SC. A. Kamal H. Khayat (Ed.) CD-Proceedings, Paper ID: MS-096 (2010, September 28)

Detailed reference viewed: 49 (4 UL)
Full Text
Peer Reviewed
See detailAnaerobe Vergärung von Mais und Cellulose - Vergleich des Abbauverhaltens
Golkowska, Katarzyna UL; Greger, Manfred UL

in Chemie Ingenieur Technik (2010), 82(9), 1514-1514

Detailed reference viewed: 135 (3 UL)
Full Text
Peer Reviewed
See detailUntersuchungen zur Oberflächenqualität von Selbstverdichtendem Beton
Weisheit; Waldmann, Danièle UL; Greger, Manfred UL

Scientific Conference (2010)

Detailed reference viewed: 38 (4 UL)
Full Text
Peer Reviewed
See detailModelling thermophilic anaerobic digestion of maize silage
Beierlein, Nomathamsanqa Nonjabulo UL; Golkowska, Katarzyna UL; Greger, Manfred UL

in Proceedings Venice 2010, Third International Symposium on energy from Biomass and Waste, 8-11.11.2010, Venice (2010)

Detailed reference viewed: 85 (3 UL)
Full Text
Peer Reviewed
See detailThermophilic digestion of cellulose at high organic loading rates
Golkowska, Katarzyna UL; Greger, Manfred UL

in Engineering in Life Sciences (2010), 10(6), 600-606

Detailed reference viewed: 107 (0 UL)
Full Text
Peer Reviewed
See detailTechnologie der Biogaserzeugung
Greger, Manfred UL; Golkowska, Katarzyna UL

in Revue Technique Luxembourgeoise (2009), 2

Detailed reference viewed: 78 (9 UL)
Full Text
Peer Reviewed
See detailThermophilic Digestion of Cellulose - Investigation of the Inhibitory State
Golkowska, Katarzyna UL; Greger, Manfred UL

in Internationale Wissenschaftstagung Biogas Science 2009 (2009)

Poster presentation at Internationale Wissenschaftstagung Biogas Science 2009

Detailed reference viewed: 27 (2 UL)
Full Text
Peer Reviewed
See detailComparative Life Cycle Assessment of biogas scenarios for Luxemburg.
Jury, C.; Benetto, E.; Welfring, J. et al

in Abstract Book of the 6th International conference on LCA the Agri-food sector. (2009)

Detailed reference viewed: 48 (1 UL)
Full Text
Peer Reviewed
See detailCement-Superplasticizer Incompatibility: hydration products involved in rheological changes
Nicolas, Edwige; Waldmann, Danièle UL; Lecomte, André et al

Scientific Conference (2008, September 10)

Detailed reference viewed: 36 (4 UL)
Peer Reviewed
See detailRheological and physico-chemical study of cement mortars with superplasticizers of polycarboxylate-type
Nicolas, Edwige UL; Waldmann, Danièle UL; Lecomte, André et al

Scientific Conference (2008, January)

Detailed reference viewed: 43 (5 UL)
Peer Reviewed
See detailSchwingfestigkeit von Leichtbauplatten mit Wabenkernstruktur.
Bauer, Josef UL; Zürbes, Arno UL; Greger, Manfred UL et al

in MP Materials Testing (2008), Bd 50 2008-9

Detailed reference viewed: 92 (6 UL)
Full Text
Peer Reviewed
See detailMonofermentation von NaWaRo - Untersuchungen der Abbaukinetik und Technologieentwicklung
Golkowska, Katarzyna UL; Greger, Manfred UL; Hüfner, V.

in Poster presentation at Biogas 2008 - Innovationskongress (2008)

Detailed reference viewed: 34 (0 UL)