Effect of two microbial phytase preparations on phosphorus utilisation in broilers fed maize-soybean meal based diets

Selostus: Fytaasientsyymilisäyksen vaikutus fosforin hyväksikäyttöön maissi-soijarouhepohjaisessa broilerrehussa

Logging residues from regeneration fellings for biofuel production - a GIS-based availability and supply cost analysis

Finland has large forest fuel resources. However, the use of forest fuels for energy production has been low, except for small-scale use in heating. According to national action plans and programs related to wood energy promotion, the utilization of such resources will be multiplied over the next few years. The most significant part of this growth will be based on the utilization of forest fuels, produced from logging residues of regeneration fellings, in industrial and municipal power and heating plants. Availability of logging residues was analyzed by means of resource and demand approaches in order to identify the most suitable regions with focus on increasing the forest fuel usage. The analysis included availability and supply cost comparisons between power plant sites and resource allocation in a least cost manner, and between a predefined power plant structure under demand and supply constraints. Spatial analysis of worksite factors and regional geographies were carried out using the GIS-model environment via geoprocessing and cartographic modeling tools. According to the results of analyses, the cost competitiveness of forest fuel supply should be improved in order to achieve the designed objectives in the near future. Availability and supply costs of forest fuels varied spatially and were very sensitive to worksite factors and transport distances. According to the site-specific analysis the supply potential between differentlocations can be multifold. However, due to technical and economical reasons ofthe fuel supply and dense power plant infrastructure, the supply potential is limited at plant level. Therefore, the potential and supply cost calculations aredepending on site-specific matters, where regional characteristics of resourcesand infrastructure should be taken into consideration, for example by using a GIS-modeling approach constructed in this study.

Microbial quality of linseed and fibre hemp plants during growing and harvest seasons

Selostus: Pellavan ja kuituhampun mikrobiologinen laatu kasvukauden aikana

The impact of bioavailability limitations on microbial stable isotope fractionation in a multiphase system

Stable isotope fractionation analysis of contaminants is a promising method for assessing biodegradation of contaminants in natural systems. However, standard procedures to determine stable isotope fractionation factors, so far, neglect the influence of pollutant bioavailability on stable isotope fractionation. On a microscale, bioavailability may vary due to the spatio-temporal variability of local contaminant concentrations, limited effective diffusivities of the contaminants and cell densities, and thus, the pollutant supply might not meet the intrinsic degradation capacity of the microorganisms. The aim of this study was to demonstrate the effect of bioavailability on the apparent stable isotope fractionation, using a multiphase laboratory setup. The data gained show that the apparent isotope fractionation factors observed during biodegradation processes depend on the amount of biomass and/or the rate of toluene mass transfer from a second to the aqueous phase. They indicate that physico-chemical processes need to be taken into account when stable isotope fractionation analysis is used for the quantification of environmental contaminant degradation.

Combustion properties of biomass residues rich in phosphorus

Tillgången på traditionella biobränslen är begränsad och därför behöver man ta fram nya, tidigare outnyttjade biobränslen för att möta de uppställda CO2 emissionsmålen av EU och det ständigt ökande energibehovet. Under de senare åren har intresset riktats mot termisk energiutvinning ur olika restfraktioner och avfall. Vid produktion av fordonsbränsle ur biomassa är den fasta restprodukten ofta den största procesströmmen i produktionsanläggningen. En riktig hantering av restprodukterna skulle göra produktionen mera lönsam och mer ekologiskt hållbar. Ett alternativ är att genom förbränning producera elektricitet och/eller värme eftersom dessa restprodukter anses som CO2-neutrala. Målsättningen med den här avhandlingen var att studera förbränningsegenskaperna hos några fasta restprodukter som uppstår vid framställning av förnybara fordonsbränslen. De fyra undersökta materialen är rapskaka, palmkärnskaka, torkad drank och stabiliserat rötslam. I studien används ett stort urval av undersökningsmetoder, från laboratorieskala till fullskalig förbränning, för att identifiera de huvudsakliga utmaningarna förknippade med förbränning av restprodukterna i pannor med fluidiserad bäddteknik. Med hjälp av detaljerad bränslekarakterisering kunde restprodukterna konstateras vara en värdefull källa för värme- och elproduktion. Den kemiska sammansättningen av restprodukterna varierar stort jämfört med mera traditionellt använda biobränslen. En gemensam faktor för alla de studerade restprodukterna är en hög fosforhalt. På grund av de låga fosforkoncentrationerna i de traditionella biobränslena har grundämnet hittills inte ansetts spela någon större roll i askkemin. Experimenten visade nu att fosfor inte mera kan försummas då man studerar kemin i förbränningsprocesser, då allt flera fosforrika bränslen tränger in på energimarknaden.

Oxidation rates of carbon and nitrogen in char residues from solid fuels

Computational fluid dynamics (CFD) modeling is an important tool in designing new combustion systems. By using CFD modeling, entire combustion systems can be modeled and the emissions and the performance can be predicted. CFD modeling can also be used to develop new and better combustion systems from an economical and environmental point of view. In CFD modeling of solid fuel combustion, the combustible fuel is generally treated as single fuel particles. One of the limitations with the CFD modeling concerns the sub-models describing the combustion of single fuel particles. Available models in the scientific literature are in many cases not suitable as submodels for CFD modeling since they depend on a large number of input parameters and are computationally heavy. In this thesis CFD-applicable models are developed for the combustion of single fuel particles. The single particle models can be used to improve the combustion performance in various combustion devices or develop completely new technologies. The investigated fields are oxidation of carbon (C) and nitrogen (N) in char residues from solid fuels. Modeled char-C oxidation rates are compared to experimental oxidation rates for a large number of pulverized solid fuel chars under relevant combustion conditions. The experiments have been performed in an isothermal plug flow reactor operating at 1123-1673 K and 3-15 vol.% O2. In the single particle model, the char oxidation is based on apparent kinetics and depends on three fuel specific parameters: apparent pre-exponential factor, apparent activation energy, and apparent reaction order. The single particle model can be incorporated as a sub-model into a CFD code. The results show that the modeled char oxidation rates are in good agreement with experimental char oxidation rates up to around 70% of burnout. Moreover, the results show that the activation energy and the reaction order can be assumed to be constant for a large number of bituminous coal chars under conditions limited by the combined effects of chemical kinetics and pore diffusion. Based on this, a new model based on only one fuel specific parameter is developed (Paper III). The results also show that reaction orders of bituminous coal chars and anthracite chars differ under similar conditions (Paper I and Paper II); reaction orders of bituminous coal chars were found to be one, while reaction orders of anthracite chars were determined to be zero. This difference in reaction orders has not previously been observed in the literature and should be considered in future char oxidation models. One of the most frequently used comprehensive char oxidation models could not explain the difference in the reaction orders. In the thesis (Paper II), a modification to the model is suggested in order to explain the difference in reaction orders between anthracite chars and bituminous coal chars. Two single particle models are also developed for the NO formation and reduction during the oxidation of single biomass char particles. In the models the char-N is assumed to be oxidized to NO and the NO is partly reduced inside the particle. The first model (Paper IV) is based on the concentration gradients of NO inside and outside the particle and the second model is simplified to such an extent that it is based on apparent kinetics and can be incorporated as a sub-model into a CFD code (Paper V). Modeled NO release rates from both models were in good agreement with experimental measurements from a single particle reactor of quartz glass operating at 1173-1323 K and 3-19 vol.% O2. In the future, the models can be used to reduce NO emissions in new combustion systems.