As a steady renewable energy technology, biogas is a viable alternative to reduce our dependency to fossil fuels and to prevent severe climate change. Biogas potential can be improved through combining different types of substrate and inoculum, as well as through substrate pre-treatments. This study aims to observe and explore the potential of macroalgae Saccharina latissima as a promising new source in renewable energy technology. The biomethane potential of macroalgae in mixture with additional substrate of mixed waste paper will be studied as a mean to improve the biogas yield. It will also compare the biomethane results of the macroalgae and the mixed substrate (macroalgae plus waste paper) exposure to non-thermal and thermal pre-treatment. In the experiment, the ratio of 3 : 1 for gr VS inoculum : gr VS substrate is used in a quantitative BMP test up to 25 days of incubation. The substrate was pre-treated mechanically (blended) into slurry and thermally through pre-heating at high temperature (130°C, 45 minutes) before digested by the inoculum. In the end of incubation period at STP (0°C and 1 atm), the highest cumulative methane yield of 260.91 Nml CH4/gr VS substrate was achieved by sample in Var – I, while the control has cumulative methane yield of 50.52 Nml CH4/gr VS. Thermally pre-treated samples resulted in lower BMP yields than the ones which were not thermally pre-treated. Through the ANOVA t-test of the methane volume and biomethane potential (BMP) yields, it is concluded that the thermal pre-treatment and waste paper addition only give little effect to biomethane production from macroalgae.

As a steady renewable energy technology, biogas is a viable alternative to reduce our dependency to fossil fuels and to prevent severe climate change. Biogas potential can be improved through combining different types of substrate and inoculum, as well as through substrate pre-treatments. This study aims to observe and explore the potential of macroalgae Saccharina latissima as a promising new source in renewable energy technology. The biomethane potential of macroalgae in mixture with additional substrate of mixed waste paper will be studied as a mean to improve the biogas yield. It will also compare the biomethane results of the macroalgae and the mixed substrate (macroalgae plus waste paper) exposure to non-thermal and thermal pre-treatment. In the experiment, the ratio of 3 : 1 for gr VS inoculum : gr VS substrate is used in a quantitative BMP test up to 25 days of incubation. The substrate was pre-treated mechanically (blended) into slurry and thermally through pre-heating at high temperature (130°C, 45 minutes) before digested by the inoculum. In the end of incubation period at STP (0°C and 1 atm), the highest cumulative methane yield of 260.91 Nml CH4/gr VS substrate was achieved by sample in Var – I, while the control has cumulative methane yield of 50.52 Nml CH4/gr VS. Thermally pre-treated samples resulted in lower BMP yields than the ones which were not thermally pre-treated. Through the ANOVA t-test of the methane volume and biomethane potential (BMP) yields, it is concluded that the thermal pre-treatment and waste paper addition only give little effect to biomethane production from macroalgae.

A cold atmospheric pressure plasma source was investigated as an alternative pre-treatment for carbon fibre reinforced epoxy substrates prior to bonding. For reference, common surface pre-treatments were also investigated (peel ply, manual abrasion, and grit blasting). In the aerospace industry, the peel ply, is usually added to one side of the composite surface during manufacture and peeled off prior to bonding. Peel ply can be used independently or in combination with other techniques. The strength of the bonded joints of the different pre-treatments was assessed through tensile lap shear tests. It was found that combining peel ply with plasma increased the joint strength by 10% whereas manual abrasion or grit blasting after peel ply improved the strength of the joints by 15% and 20% respectively. The effect of pre-treating the composite substrate side without peel ply (bag side) was also investigated. The strength of the joints produced without any pre-treatment was increased by 99% for manual abrasion, 134% for grit blasting and by 146% for plasma. Comparing both surfaces of the composite substrates, it was found that using peel ply improved the performance of the joints by 91%. In order to understand better the effects of the different pre-treatments, surface characterisation of the substrates (surface roughness, surface free energy, and analysis of chemical changes) was also conducted. The effect of roughness did little to affect the strength values (for both surfaces of the composite). The adhesive used in this research was very good at wetting the surface, regardless of the roughness. However, when the adhesive was able to wet the surface, the relationship between bond strength and surface free energy was unclear. Plasma was shown to increase levels of oxygen at the surface and reduce/eliminate the concentration of fluorine at the surface on the bag side of the composite.

This thesis is focused on the novel wood chip refining process called AdvancedThermomechanical Pulp (ATMP) refining. ATMP consists of mechanical pretreatmentof chips in Impressafiner and Fiberizer prior to first stage refining atincreased intensity. Process chemicals (this study was concentrated on hydrogenperoxide and magnesium hydroxide) are introduced into the first stage refiner.It is known that the use of chemicals in TMP process and first stage refining atelevated intensity can reduce the energy demands of refining. The downside is thatthey also alter the character of the produced pulp. Reductions in fibre length andtear index are usually the consequences of refining at elevated intensity. Additionof chemicals usually leads to reduction of the light scattering coefficient. Usingstatistical methods it was shown that it is possible to maintain the TMP character ofthe pulp using the ATMP process. This is explained by a separation of thedefibration and the fibre development phases in refining. This separation allowsdefibration of chips to fibres and fibre bundles without addition of chemicals orincrease in refining intensity. Chemicals are applied in the fibre developmentphase only (first stage refiner). The energy demand in refining to reach tensileindex of 25 Nm/g was reduced by up to 1.1 MWh/odt (42 %) using the ATMPprocess on Loblolly pine. The energy demand in refining of White spruce, requiredto reach tensile index of 30 Nm/g, was reduced by 0.65 MWh/odt (37%).Characterizations of individual fibre properties, properties of sheets made fromlong fibre fractions and model fibre sheets with different fines fractions werecarried out. It was established that both the process equipment configuration (i.e.the mechanical pre‐treatment and the elevated refining intensity) and the additionof process chemicals in the ATMP process influence fibre properties such as external and internal fibrillation as well as the amount of split fibres. Improvementof these properties translated into improved properties of sheets, made from thelong fibre fractions of the studied pulps. The quality of the fines fraction alsoimproved. However, the mechanisms of improvement in the fines quality seem tobe different for fines, generated using improved process configuration andaddition of process chemicals. The first type of fines contributed to better bondingof model long fibre sheets through the densification of the structure. Fines whichhave been influenced by the addition of the process chemicals seemed in additionto improve bonding between long fibres by enhancing the specific bond strength.The improved fibre and fines properties also translated into better airpermeability and surface roughness of paper sheets, properties which areespecially important for supercalendered (SC) printing paper. The magnitude offibre roughening after moistening was mainly influenced by the processequipment configuration while the addition of process chemicals yielded lowestfinal surface roughness due to the lowest initial surface roughness. There was nodifference in how fines fractions from the studied processes influenced the fibreroughening. However, fines with better bonding yielded model fibre sheets withhigher PPS, probably due to their consolidation around fibre joints. Hence, thedecrease in PPS can probably be attributed to the improvements in the long fibrefraction properties while the improvement of fines quality contributed to thereduction of air permeability.The process chemicals, utilized in the ATMP process (Mg(OH)2 and H2O2) alsoproved to be an effective bleaching system. Comparable increases in brightnesscould be reached using the ATMP process and conventional tower bleaching.Maximum brightness of the pulp was reached after approximately 10 minutes ofhigh‐consistency storage after refining or 40 minutes of conventional bleaching.This study was conducted using a pilot scale refiner system operated as a batchprocess. Most of the experiments were performed using White spruce (Piceaglauca). In Paper I, Loblolly pine (Pinus taeda) was used. It is believed that theresults presented in this thesis are valid for other softwood raw materials as well,but this limitation should be considered.

This diploma thesis deals with the design of hydraulic trash rack cleaning machine for waste water treatment plant. The first part of the thesis describes methods of removing coarse impurities from intake water to technological equipment. Furthermore, a specific design including calculation and choice of the drive is made. Part of the work is also solving the course of force effects and strength analysis of the most stressed parts. The work also deals with the comparison of design solution of hydraulic and mechanical drive of the machine. The attachment contains a drawing of the cleaning machine assembly and selected welded complex.

This master’s thesis deals with design of mechanical screen cleaning machine for wastewater treatment plant, which will be placed in 800 mm wide and 1 850 mm deep intake canal. Thesis includes research of produced systems, construction design, drive unit design and other necessary strength and technical calculations. Thesis is supplemented by drawing of machine and its details.