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Nitrate leaching was studied on a 2.4-ha subsurface-drained corn (Zea mays L.) field in southwestern Quebec. The soil was a sandy loam to loamy sand (mean depth 46 cm) overlying clay. Treatments, begun in fall 1991, consisted of no-till, reduced tillage, and conventional tillage with crop residues either removed or retained at harvest. Drain flow volume and NO$ sb3 sp-$-N concentrations in flow were monitored year-round, and soil NO$ sb3 sp-$-N levels measured in spring and fall. A total of 34 kg NO$ sb3 sp-$-N ha$ sp{-1}$ was recorded in drain flow in 1992 from the site as a whole, equivalent to 20% of applied fertilizer N. In the first 14 months of monitoring, over 70% of water samples had NO$ sb3 sp-$-N levels exceeding Canadian drinking water guidelines (10 mg NO$ sb3 sp-$-N L$ sp{-1}),$ and about 25% had over 40 mg NO$ sb3 sp-$-N L$ sp{-1}.$ Flow-weighted mean concentration for the site as a whole in 1992 was 19 mg NO$ sb3 sp-$-N L$ sp{-1}.$ Unanticipated variations in drain depth significantly affected flow volume and total NO$ sb3 sp-$-N losses, hampering assessment of treatment effects on drain water parameters. In 1992, post-harvest soil NO$ sb3 sp-$-N levels at 0-25 cm were significantly lower in plots with crop residues retained, regardless of tillage system, than in plots with residues removed. In May 1993 (pre-tillage), soil NO$ sb3 sp-$-N levels were similar for all treatments, having dropped in no-residue plots and risen slightly in plots with residues, suggesting immobilization of NO$ sb3 sp-$-N by crop residues in summer-fall and mineralization in spring. The NO$ sb3 sp-$-N measured in drain flow represents a substantial loss of N from the farm system, and has negative implications for water quality. Within the time-frame of the study, crop residues appeared to have a greater effect on soil NO$ sb3 sp-$-N levels, and thus leaching potential, than did tillage system.

A two year study was conducted on the Macdonald Campus Farm on a 2.4 ha site of shallow St. Amble loamy sand cropped to corn (Zea mays L.). Three types of tillage practice (conventional tillage, reduced tillage, and no-till) were combined with 2 residue levels (with and without) in a randomized complete block design. The effect of these practices on NO 3--N distribution at 0--50 cm in the soil profile, and on plant N uptake were studied. Organic matter, pH, bulk density, and soil moisture contents were also monitored. Residues were found to have a greater influence on soil NO3--N transformations (mineralization and immobilization), than tillage. In July 1996 residues suppressed NO3--N levels in reduced tillage (RT), but increased NO3--N levels in conventional tillage (CT). Residues initially increased N03--N levels in no-till (NT), but a few weeks later caused a sharp decline in NO 3--N levels in NT. In August 1996, RT and NT treatments without residue were found to have much greater concentrations of NO 3--N than those with residue. The effect of N suppression caused by residues was observed in Spring 1996, July 1996, August 1996, and August 1997. Reduced tillage demonstrated less NO 3--N fluctuation than the other tillage treatments. Wheel tracked rows had up to 20 times more NO3--N at 0--15 cm than the non wheel tracked rows, caused by the uneven distribution of N fertilizer. However, high NO3--N levels in the wheel tracked rows decreased to levels comparable with those in non fertilized (non wheel track) rows at 50 cm. Corn yields were not affected by tillage or residue treatments, neither were they influenced by the percentage of tissue N content. (Abstract shortened by UMI.)

New Zealand has ratified the Kyoto Protocol and agreed to reduce greenhouse gas emissions to 1990 levels in the first commitment period 2008-2012. Energy generated from renewable sources, such as New Zealand plantation forests and wood processing sites, is considered greenhouse gas neutral. But the use of biomass for bioenergy in New Zealand is very small. Some of the reasons for this include a lack of information about the future fuel supply and delivered cost. This thesis aims to provide a methodology to estimate biomass fuel availability and the delivered cost, of a range of forest and wood processing sources within a district, and to analyse the impact of harvest age, harvesting practices, terrain, collection and chipping costs, opportunity cost and transport costs on the availability and delivered cost of biomass for bioenergy. The six biomass streams included were chiplogs, forest landing residues, cutover residues, sawdust, bark and chip. The methodology was developed based on an area in Canterbury, and tested on an area in the Nelson/Marlborough region. It utilises forest growth models, Geographic Information Systems and Microsoft Excel. Growth models allow the analysis to be customised to a particular area or region, while the use of GIS allows the model to take spatial aspects (for example slope and transport distance) into consideration. Developing the overall framework within Excel allows easy analysis of the results and changes to the underlying assumptions. Opportunity costs make up a large proportion of the total cost of delivery for the chiplog, sawdust, bark and chip biomass and need to be included in any estimate of cost for these biomass streams. The logistic system chosen for collecting and chipping the forest residues has a large impact on their delivered cost as do the transport costs. However transport cost is not the most significant influence on the delivered cost of other biomass streams. The use of biomass for electricity generation only is not currently economic in either of the areas analysed. The use of biomass for heat production is currently economic if compared to the electricity purchase price.

The aim of this study was to estimate how different filling materials affect the mobilization of pollution residue in remediated soil. The aim was also to assess criteria that should be fulfilled for the soil properties of these filling materials. The study was partly based on target value calculations where the impact of varied TOC, hydraulic conductivity and porosity affected the mobility of toluene, trichloroethene, benso(a)pyrene and arsenic residue in the soil. An evaluation of the potential mobility of soil pollution residues where filling materials had been used was carried out for five different locations in Sweden. Soil samples were collected before remediation of contaminated soil, and afterwards when the fillings were restored. Sample analyzes were made for TOC and soil water. The results from the study show that the TOC and porosity content in filling materials has a significant impact on the mobility of soil pollution residues. Filling materials with less TOC than the remediated soil will contribute to an increased mobility of organic pollution residues to the air, surface water and groundwater, whilst lower soil porosity, or rather lower soil water content will contribute to an increased mobility of airborne pollution residues. The results also show that in Sweden the use of filling materials with both lower TOC and soil water content is common. To avoid an increased mobilization of pollution residues from remediated soils, filling materials should contain TOC and soil water equals the contents in the remediated soil.

The modern concept of “biorefinery” is dominantly based on chemical pulp mills to create more value than cellulose pulp fibres, and energy from the dissolved lignins and hemicelluloses. This concept is characterized by the conversion of biomass into various bio-based products. It includes thermochemical processes such as gasification and fast pyrolysis. In thermo-mechanical pulp (TMP) mills, the feedstock available to the gasification-based biorefinery is significant, including logging residues, bark, fibre material rejects, bio-sludges and other available fuels such as peat, recycled wood and paper products. On the other hand, mechanical pulping processes consume a great amount of electricity, which may account for up to 40% of the total pulp production cost. The huge amount of purchased electricity can be compensated for by self-production of electricity from gasification, or the involved cost can be compensated for by extra revenue from bio-transport fuel production. This work is to study co-production of bio-automotive fuels, bio-power, and steam via gasification of the waste biomass streams in the context of the mechanical pulp industry. Ethanol and substitute natural gas (SNG) are chosen to be the bio-transport fuels in the study. The production processes of biomass-to-ethanol, SNG, together with heat and power, are simulated with Aspen Plus. Based on the model, the techno-economic analysis is made to evaluate the profitability of bio-transport fuel production when the process is integrated into a TMP mill.The mathematical modelling starts from biomass gasification. Dual fluidized bed gasifier (DFBG) is chosen for syngas production. From the model, the yield and composition of the syngas and the contents of tar and char can be calculated. The model has been evaluated against the experimental results measured on a 150 KWth Mid Sweden University (MIUN) DFBG. As a reasonable result, the tar content in the syngas decreases with the gasification temperature and the steam to biomass (S/B) ratio. The biomass moisture content is a key parameter for a DFBG to be operated and maintained at a high gasification temperature. The model suggests that it is difficult to keep the gasification temperature above 850 ℃ when the biomass moisture content is higher than 15.0 wt.%. Thus, a certain amount of biomass or product gas needs to be added in the combustor to provide sufficient heat for biomass devolatilization and steam reforming.For ethanol production, a stand-alone thermo-chemical process is designed and simulated. The techno-economic assessment is made in terms of ethanol yield, synthesis selectivity, carbon and CO conversion efficiencies, and ethanol production cost. The calculated results show that major contributions to the production cost are from biomass feedstock and syngas cleaning. A biomass-to-ethanol plant should be built over 200 MW.In TMP mills, wood and biomass residues are commonly utilized for electricity and steam production through an associated CHP plant. This CHP plant is here designed to be replaced by a biomass-integrated gasification combined cycle (BIGCC) plant or a biomass-to-SNG (BtSNG) plant including an associated heat & power centre. Implementing BIGCC/BtSNG in a mechanical pulp production line might improve the profitability of a TMP mill and also help to commercialize the BIGCC/BtSNG technologies by taking into account of some key issues such as, biomass availability, heat utilization etc.. In this work, the mathematical models of TMP+BIGCC and TMP+BtSNG are respectively built up to study three cases: 1) scaling of the TMP+BtSNG mill (or adding more forest biomass logging residues in the gasifier for TMP+BIGCC); 2) adding the reject fibres in the gasifier; 3) decreasing the TMP SEC by up to 50%.The profitability from the TMP+BtSNG mill is analyzed in comparison with the TMP+BIGCC mill. As a major conclusion, the scale of the TMP+BIGCC/BtSNG mill, the prices of electricity and SNG are three strong factors for the implementation of BIGCC/BtSNG in a TMP mill. A BtSNG plant associated to a TMP mill should be built in a scale above 100 MW in biomass thermal input. Comparing to the case of TMP+BIGCC, the NR and IRR of TMP+BtSNG are much lower. Political instruments to support commercialization of bio-transport fuel are necessary. / Gasification-based Biorefinery for Mechanical Pulp Mills

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Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1989. / Includes bibliographical references (leaves 201-215) / Microfiche. / xxi, 215 leaves, bound ill. 29 cm

Typescript. / Thesis (Ph. D.)--University of Hawaii, 1970. / Bibliography: leaves [215]-226. / Microfilm. / xix, 226 l diagrs

Examensarbete.