Lene Pedersen

Biochemical methane potential and anaerobic biodegradability of non-herbaceous and herbaceous phytomass in biogas production

The suitability of municipal plant waste for anaerobic digestion was examined using 57 different herbaceous and non-herbaceous samples. Biochemical methane potential (BMP) and anaerobic biodegradability were related to the degree of lignification and crystallinity of cellulose. The BMP of herbaceous garden plants (332.7 CH(4)NL kg VS(-1)) was high, although lower than that of energy crops (400-475 CH(4)NL kg VS(-1)). Herbaceous wild plants from natural grassland contained most lignocelluloses, leading to relatively low BMP (214.0 CH(4)NL kg VS(-1)). Non-herbaceous phytomass had a high degree of lignification and a high concentration of crystalline cellulose, but due to the content of non-woody parts with a low concentration of lignocellulose the BMP was relatively high, 199.9 and 172.0 CH(4)NL kg VS(-1) for hedge cuttings and woody cuttings, respectively. There were indications that a plant lignin concentration of 100 g kg VS(-1) is the critical biodegradability point in anaerobic digestion of phytomass.

Rheological properties of biscuit dough from different cultivars, and relationship to baking characteristics

Abstract Rheological properties of semi-sweet biscuit doughs from eight wheat cultivars were studied, and related to the dimensional changes of biscuits after cutting and baking. The tested cultivars were selected in order to represent a wide diversity in biscuit baking performance, and were grown with low use of N-fertiliser in three successive years. A standard recipe for semi-sweet biscuit dough was used, and the amount of water added was adjusted to the water absorption capacity. The rheological properties of the dough were characterised by creep recovery and oscillation. The fundamental methods showed that maximum strain at creep, recovery, storage modulus G ′, and phase angle δ were significantly influenced by the tested cultivars. The ranking of the cultivars according to phase angle δ was identical in each of the years investigated 3 which indicates that phase angle δ reflects differences in structural properties with genetic control. Multivariate regression of flour physiochemical, dough rheological, and biscuit baking characteristics showed that a decrease in biscuit length was correlated under several rheological parameters, including phase angle δ , Farinograph and creep recovery parameters. Sedimentation value was the only physiochemical flour characteristic with considerable influence on the model. Validation of the partial least squares-model including all samples from the 3 years gave only a weak correlation ( r =0.58), whereas when each single year was evaluated separately, the correlation increased considerably ( r =0.71 and 0.87).

Validation and Recommendation of Methods to Measure Biogas Production Potential of Animal Manure

In developing countries, biogas energy production is seen as a technology that can provide clean energy in poor regions and reduce pollution caused by animal manure. Laboratories in these countries have little access to advanced gas measuring equipment, which may limit research aimed at improving local adapted biogas production. They may also be unable to produce valid estimates of an international standard that can be used for articles published in international peer-reviewed science journals. This study tested and validated methods for measuring total biogas and methane (CH4) production using batch fermentation and for characterizing the biomass. The biochemical methane potential (BMP) (CH4 NL kg−1 VS) of pig manure, cow manure and cellulose determined with the Moller and VDI methods was not significantly different in this test (p>0.05). The biodegradability using a ratio of BMP and theoretical BMP (TBMP) was slightly higher using the Hansen method, but differences were not significant. Degradation rate assessed by methane formation rate showed wide variation within the batch method tested. The first-order kinetics constant k for the cumulative methane production curve was highest when two animal manures were fermented using the VDI 4630 method, indicating that this method was able to reach steady conditions in a shorter time, reducing fermentation duration. In precision tests, the repeatability of the relative standard deviation (RSDr) for all batch methods was very low (4.8 to 8.1%), while the reproducibility of the relative standard deviation (RSDR) varied widely, from 7.3 to 19.8%. In determination of biomethane concentration, the values obtained using the liquid replacement method (LRM) were comparable to those obtained using gas chromatography (GC). This indicates that the LRM method could be used to determine biomethane concentration in biogas in laboratories with limited access to GC.

Biogas Production from Vietnamese Animal Manure, Plant Residues and Organic Waste: Influence of Biomass Composition on Methane Yield

Anaerobic digestion is an efficient and renewable energy technology that can produce biogas from a variety of biomasses such as animal manure, food waste and plant residues. In developing countries this technology is widely used for the production of biogas using local biomasses, but there is little information about the value of these biomasses for energy production. This study was therefore carried out with the objective of estimating the biogas production potential of typical Vietnamese biomasses such as animal manure, slaughterhouse waste and plant residues, and developing a model that relates methane (CH4) production to the chemical characteristics of the biomass. The biochemical methane potential (BMP) and biomass characteristics were measured. Results showed that piglet manure produced the highest CH4 yield of 443 normal litter (NL) CH4 kg−1 volatile solids (VS) compared to 222 from cows, 177 from sows, 172 from rabbits, 169 from goats and 153 from buffaloes. Methane production from duckweed (Spirodela polyrrhiza) was higher than from lawn grass and water spinach at 340, 220, and 110.6 NL CH4 kg−1 VS, respectively. The BMP experiment also demonstrated that the CH4 production was inhibited with chicken manure, slaughterhouse waste, cassava residue and shoe-making waste. Statistical analysis showed that lipid and lignin are the most significant predictors of BMP. The model was developed from knowledge that the BMP was related to biomass content of lipid, lignin and protein from manure and plant residues as a percentage of VS with coefficient of determination (R-square) at 0.95. This model was applied to calculate the CH4 yield for a household with 17 fattening pigs in the highlands and lowlands of northern Vietnam.

Characteristics of Animal Slurry as a Key Biomass for Biogas Production in Denmark

Climate change has become an important global issue and animal manure has been pointed out as a major source of greenhouse gas (GHG) emissions. The Danish government targets animal manure as a key biomass with the aim of producing renewable fuels and reducing GHG emissions. Animal manure is a mixture of excreta and materials added during management. Apart from the major part of animal slurry which is feces and urine, animal slurry is composed of many materials, i.e., sand, water from cleaning, small branches and straw from the bedding materials. Thereby a wide variation of characteristics can be found depending on different management systems, animal type and diet, etc. which make for difficulties in the estimation of manure quality for biogas production.

Rapid estimation of the biochemical methane potential of plant biomasses using Fourier transform mid-infrared photoacoustic spectroscopy

Biochemical methane potential (BMP) is a very important characteristic of a given feedstock for optimisation of its use in biogas production. However, the long digestion time needed to determine BMP is the main limitation for the use of this assay during the operation of anaerobic digesters to produce biogas. Fourier transform mid-infrared photoacoustic spectroscopy (FTIR-PAS) was used to predict the BMP of 87 plant biomasses. The developed calibration model was able to explain 81% of the variance in the measured BMP of a selected test set with a root mean square error (RMSE) of 40NLCH4kg(-1) of volatile solids (VS) and a ratio of performance to deviation (RPD) of 2.38. The interpretation of the regression coefficients used in the calibration revealed a positive correlation of BMP with easily degradable compounds (amorphous cellulose, hemicellulose and aliphatic compounds) and a negative correlation with inhibitors of cellulose hydrolysis (lignin, hemicellulose).

Bulk Functionality Diversification by Unsupervised Single-Kernel Near-Infrared (SKNIR) Sorting of Wheat

ABSTRACT We explored the effects of fractioning heterogeneous bulk wheat by fast unsupervised single-kernel near-infrared (SKNIR) sorting according to an internal complex NIR functionality trait using a fast prototype kernel sorter designed for postharvest bulk sorting. Sorting into three functionality fractions was performed on low quality lots from an organic field experiment from two growth years and two locations. Sorted lots were mixtures originally diversified by three different preceding catch crops. The resulting 12 fractions, as well as the 12 original wheat lots were characterized by 20 standard quality variables of grains and flours. The data was analyzed by principal component analysis (PCA) and analysis of variance (ANOVA). Within each year and location/cultivar, the SKNIR fractionation had significant positive effect on bulk grain density, protein, wet gluten content, Zeleny sedimentation volume, farinograph water absorption, farinograph softening, falling number, gelatinization temperature,...

Single-kernel near infrared analysis of bulk wheat heterogeneity a theory of sampling reference study

Most often an analytical result, be it a destructive standard analysis or a non-destructive NIR spectrum, is a property estimate measured on an analytical volume considerably smaller than the volume of the lot (L) being characterised. The inevitable estimation errors generated during the mass reduction process, together with analysis, are substantiated by Pierre Gy’s Theory of Sampling (TOS),

Influence of freezing/thawing and drying/milling on Biochemical Methane Potential

Abstract In studies of biochemical methane production (BMP) researchers often collate a large number of samples at the same time for a sample archive. The samples are often frozen to avoid microbial transformation, further homogenized by grinding. We studied the influence of subfreezing/thawing and drying/milling of energy crop on BMP and anaerobic biodegradability (BD). Relative standard deviation (RSD, %) between the BMP of controls and of the subfrozen was in the range 2.1–9.0%, and of the dried/milled 3.1–17.5%. Whereas biodegradability of the controls was 72.3(±16.3)%, that of the pretreated was slightly lower at 70.5(±14.7)% for the subfrozen and 69.7(±18.4)% for the dried/milled.