Measurement and Improvement of Wet Paper Web Strength

Various strength properties of paper are measured to tell how well it resists breaks in a paper machine or in printing presses. The most often measured properties are dry tensile strength and dry tear strength. However, in many situations where paper breaks, it is not dry. For example, in web breaks after the wet pressing the dry matter content can be around 45%. Thus, wet-web strength is often a more critical paper property than dry strength. Both wet and dry strength properties of the samples were measured with a L&W tensile tester. Originally this device was not designed for the measurement of the wet web tensile strength, thus a new procedure to handle the wet samples was developed. The method was tested with Pine Kraft (never dried). The effect of different strength additives on the wet-web and dry paper tensile strength was studied. The polymers used in this experiment were aqueous solution of a cationic polyamidoamine-epichlorohydrin resin (PAE), cationic hydrophilised polyisocyanate and cationic polyvinylamine (PVAm). From all three used chemicals only Cationic PAE considerably increased the wet web strength. However it was noticed that at constant solids content all chemicals decreased the wet web tensile strength. So, since all chemicals enhanced solid content it can be concluded that they work as drainage aids, not as wet web strength additives. From all chemicals only PVAm increased the dry strength and two other chemicals even decreased the strength. As chemicals were used in strong diluted forms and were injected into the pulp slurry, not on the surface of the papersheets, changes in samples densities did not happen. Also it has to be noted that all these chemicals are mainly used to improve the wet strength after the drying of the web.

VOC emissions and control techniques in softwood veneer dryers

The objective in this Master’s Thesis was to determine VOC emissions from veneer drying in softwood plywood manufacturing. Emissions from plywood industry have become an important factor because of the tightened regulations worldwide. In this Thesis is researched quality and quantity of the VOCs from softwood veneer drying. One of the main objectives was to find out suitable cleaning techniques for softwood VOC emissions. In introduction part is presented veneer drying machines, wood mechanical and chemical properties. VOC control techniques and specified VOC limits are introduced also in the introduction part. Plywood mills have not had interest to VOC emissions previously nevertheless nowadays plywood mills worldwide must consider reduction of the emissions. This Thesis includes measuring of emissions from softwood veneer dryer, analyzation of measured test results and reviewing results. Different air conditions inside of the dryer were considered during planning of the measurements. Results of the emissions measurements were compared to the established laws. Results from this Thesis were softwood veneer dryer emissions in different air conditions. Emission control techniques were also studied for softwood veneer dryer emissions for further specific research.

Yhdyskuntalietteiden terminen käsittely ja prosessissa syntyvän tuhkan jalostaminen fosforilannoitteeksi Lappeenrannan alueella

Tässä diplomityössä on selvitetty yhdyskuntalietteiden ominaisuuksia sekä käsittelymenetelmiä keskittyen termiseen käsittelyyn, jolla tässä työssä tarkoitetaan lietteen termistä kuivausta ja polttoa. Työssä on myös selvitetty lietteen poltossa syntyvän tuhkan ominaisuuksia ja niiden sopivuutta lannoitteen raaka-aineena. Fosforimalmin varannot ovat rajalliset ja olettavaa on, että helposti hyödynnettävissä oleva fosforimalmi loppuu noin sadan vuoden kuluessa, mikäli fosforin kulutus pysyy nykyisellä tasolla. Kun lietettä poltetaan, jää lietteessä oleva fosfori tuhkaan. Lietteenpoltossa syntyvät tuhkat sisältävät fosforin lisäksi erilaisia haitta-aineita, joten tuhkan sisältämää fosforia ei kyetä hyödyntämään ilman käsittelyä. Työn case-osassa on selvitetty Lappeenrannan alueella syntyvä yhdyskuntalietemäärä sekä sen hyötykäyttömahdollisuudet alueellisessa lietteen polttolaitoksessa. Lappeenrannan tapauksessa syntyvä lietetuhkan määrä on arvioitu ja määritetty paljonko tuhkasta olisi tulevaisuudessa mahdollisuus jalostaa fosforilannoitetta. Tutkimuksen lopputuloksena voidaan todeta, että lietteen poltto ja polton tuhkan käyttö lannoitteena ei vielä kokonaisprosessina ole toteutettavissa oleva vaihtoehto, mutta teknologisen kehityksen jatkuessa se voisi olla potentiaalinen vaihtoehto yhdyskuntalietteen ja lietetuhkan käsittelyn kokonaisratkaisuksi.

Dewatering of hard-to-dewater pulps

Nanocellulose has much potential for enhancing the tensile strength of paper but it slows down significantly drainage, restricting its use in industrial scale. Main objective of the work was to find ways to improve the dewatering of nanocellulose-containing papers. The effects of cationic potato starch, microparticle system and filler addition on dewatering and such key properties as formation, tensile strength and air permeance of manufactured paper were studied. Test points had 0, 4 or 8 % CNF and 0, 15 or 30 % PCC content. Based on earlier studies, 25 mg/g starch dosage was added to some test points. Modern microparticle system, consisted of cationic polyacrylamide and amorphous silica, was used in few test points. Dosages for both components were 0.3 and 0.6 mg/g, following the recommendations of the supplier. Also, the influences of CNF and filler on drying behaviour after different stages (drainage, wet pressing and cylinder drying) were estimated. Following trends were observed. Starch does not have unambiguous influence on dewatering. In some cases, it improved drainage slightly but effects on the properties of end product were discovered small. Filler quickened dewatering but large proportions were noticed to be detrimental for the drainage, air permeance and tensile strength. Microparticle system improved drainage notably, especially if CNF dosage was high. In addition, microparticle system increased tensile strength and decreased air permeance. However, its effects on formation were detrimental. Dewatering of nanocellulose-containing furnishes is treatable up to a certain point. In the end, such drainage times that were measured from test points which consisted only of pure kraft pulps are awkward to reach.

Kuivurin pölynhallintajärjestelmä

Lämminilmakuivaus on viljan kuivaamisen menetelmistä ylivoimaisesti käytetyin. Siinä kuivurissa olevan viljakerroksen läpi puhalletaan lämmintä ilmaa, kunnes viljan kosteuspitoisuus laskee tavoitetasoon. Viljan jyvistä irtoaa aina pölyä niiden hangatessa toisiaan vasten. Viljankuivaamoiden pölyisyyttä on normaalisti pyritty vähentämään poistamalla leijuvaa pölyä viljan liikkeen epäjatkuvuuskohdista. Pölyä kulkeutuu kuitenkin kuivaamon ulkopuolelle myös kuivaukseen käytetyn ilman mukana. Poistoilman pölypitoisuus ei tavallisesti ole korkea, mutta kuivaamiseen käytetyistä suurista ilmamääristä johtuen pölyä voi kertyä poistoilmakanavan ympäristöön huomattavia määriä. Tämän diplomityön tavoitteena onkin viljankuivurin poistoilman pölypitoisuuden vähentämiseen soveltuvan pölynhallintajärjestelmän kehittäminen. Selvityksessä tarkasteltiin ensinnäkin kuivurin poistoilman pölypitoisuuteen liittyvää kansallista ja kansainvälistä lainsäädäntöä sekä raja-arvoja. Lähdemateriaalin perusteella kartoitettiin pölypitoisuuden vähentämiseen soveltuvia menetelmiä sekä kilpailijoiden toteuttamia ratkaisuja. Myös muita pölynhallintajärjestelmän edellytyksiä selvitettiin. Teoreettisessa tarkastelussa teknistaloudellisesti parhaaksi osoittautunut pölynhallintaratkaisu jalostettiin prototyypiksi. Sen toimintakykyä testattiin erotustehokkuuden mittaamiseen soveltuvan koelaitteiston avulla. Testitulosten perusteella kyseinen pölynhallintajärjestelmä todettiin toimivaksi ja pienellä jatkokehittelyllä myös kaupalliseen käyttöön soveltuvaksi. Testitulosten hyödyntämismahdollisuuksien lisäksi diplomityössä esitetään myös muutamia jatkokehitysehdotuksia.

Mädätysjäännöksen tuotteistamismahdollisuudet Kymenlaaksossa

Biokaasun tuotantoa ollaan selvästi lisäämässä Suomessa. Biokaasutuksen kokonaishyödyn kannalta on olennaista, että mädätyksen lopputuote eli mädätysjäännös saadaan lannoitekäyttöön. Tämän työn tavoitteena oli selvittää Kymenlaakson Jäte Oy:n mahdollisuuksia tuotteis-taa Kymen Bioenergia Oy:n yhteismädätyslaitoksen mädätysjäännöstä. Työssä keskityttiin hyötykäyttövaihtoehdoista lannoitekäyttöön maanviljelyssä sekä tilanteeseen jossa mädätyslaitos käsittelee sekä puhdistamolietettä että biojätettä ja mädätysjäännös kuivataan mekaanisesti. Mekaanisesti kuivatun mädätysjäännöksen ensisijaiset tuotteistamisvaihtoehdot maanviljelyyn ovat joko jäännös sellaisenaan tai termisesti kuivattuna ja rakeistettuna, eli kuivarakeena. Mäkikylän laitoksen mädätysjäännöksen arvo peltolannoitteena on syyskuun 2010 keinolannoit-teiden hintaan vertaamalla sellaisenaan noin 1–20 €/t ja kuivarakeena noin 2–60 €/t. Arvo riippuu siitä, miten tuotteiden typpeä ja fosforia huomioidaan kasveille käyttökelpoiseksi. Täl-lä hetkellä käyttökelpoisin tapa on ympäristötuen puhdistamolietetuotteita koskevien ehtojen mukaisesti ottaa huomioon vesiliukoinen typpi ja 40 % kokonaisfosforista. Tällöin mädätys-jäännöksen arvo on noin 6 €/t ja kuivarakeen n. 18 €/t. Käytön kannalta kuivarae on helpompi vaihtoehto ja alueen viljelijät ovat heille tehdyn kyselyn mukaan varsin kiinnostuneita kuivarakeesta lannoitteena. Muista tuotteistusvaihtoehdoista termisesti kuivaamalla mädätysjäännöksen tehollinen lämpö-arvo saapumistilassa on noin 10 MJ/kg. Vastaava arvo jyrsinturpeen kesäkuun 2010 hinnan mukaan on noin 30 €/t. Tuotteen soveltuvuus polttoon tulee silti varmistaa. Termisesti kuiva-tulla mädätysjäännöksellä on tuotteistamismahdollisuuksia hieman laajemmin kuin kompostoidulla. Kompostoidun mädätysjäännöksen tuotteistamisen lähtökohta on lähinnä viherrakentaminen. Maanviljelykäyttöä ajatellen mädätysjäännöstä ei välttämättä tarvitse kompostoida.

Microscopic simulation of pigment coating consolidation

The control of coating layer properties is becoming increasingly important as a result of an emerging demand for novel coated paper-based products and an increasing popularity of new coating application methods. The governing mechanisms of microstructure formation dynamics during consolidation and drying are nevertheless, still poorly understood. Some of the difficulties encountered by experimental methods can be overcome by the utilisation of numerical modelling and simulation-based studies of the consolidation process. The objective of this study was to improve the fundamental understanding of pigment coating consolidation and structure formation mechanisms taking place on the microscopic level. Furthermore, it is aimed to relate the impact of process and suspension properties to the microstructure of the coating layer. A mathematical model based on a modified Stokesian dynamics particle simulation technique was developed and applied in several studies of consolidation-related phenomena. The model includes particle-particle and particle-boundary hydrodynamics, colloidal interactions, Born repulsion, and a steric repulsion model. The Brownian motion and a free surface model were incorporated to enable the specific investigation of consolidation and drying. Filter cake stability was simulated in various particle systems, and subjected to a range of base substrate absorption rates and system temperatures. The stability of the filter cake was primarily affected by the absorption rate and size of particles. Temperature was also shown to have an influence. The consolidation of polydisperse systems, with varying wet coating thicknesses, was studied using imposed pilot trial and model-based drying conditions. The results show that drying methods have a clear influence on the microstructure development, on small particle distributions in the coating layer and also on the mobility of particles during consolidation. It is concluded that colloidal properties can significantly impact coating layer shrinkage as well as the internal solids concentration profile. Visualisations of particle system development in time and comparison of systems at different conditions are useful in illustrating coating layer structure formation mechanisms. The results aid in understanding the underlying mechanisms of pigment coating layer consolidation. Guidance is given regarding the relationship between coating process conditions and internal coating slurry properties and their effects on the microstructure of the coating.

Kaatopaikkakaasun hyväksikäyttö lietteen kuivauksessa

Tällä hetkellä suuri osa esikäsiteltyjen jätevesilietteiden loppusijoitusvaihtoehdoista ei pysty kattamaan lopullisesti kasvavien lietemäärien loppusijoitustarvetta, mikä lisää lietteen loppusijoitusta kaatopaikoille. Kuitenkin EU:n tiukentuneen jätehuoltolainsäädännön sekä ilmastonlämpenemisen suurien haasteiden vuoksi, kaatopaikoille sijoitettavien jätteiden määrää täytyy pyrkiä vähentämään. Tämän työn tavoitteena on tutkia jätevedenpuhdistamoilta tulevan lietteen termistä kuivausta yhtenä lietteenkäsittely vaihtoehtona. Tavoitteena on selvittää voidaanko lietettä kuivaamalla saada liete paremmin hyödynnetyksi. Työssä tarkasteltiin yleisesti yhdyskuntalietteen termisessä kuivaamisessa nykyisin käytettäviä menetelmiä, sen ympäristövaikutuksia, energian tarvetta ja kustannuksia sekä siitä saatavaa hyötyä lietteen loppusijoittamisessa. Lisäksi arvioitiin kuinka kaatopaikkakaasun hyödyntäminen soveltuisi lietteen kuivauksessa tarvittavan energian tuotantoon. Työssä tehdyn selvityksen mukaan kaatopaikkakaasua voidaan hyödyntää suhteellisen helposti lämmöntuotannossa ilman merkittäviä laitosmuutoksia tai kaasun puhdistusta. Ongelmana pidettiin kaatopaikkakaasun kuljetuksia, joka on suhteellisen vaikeaa ja taloudellisesti kannattamatonta. Kuitenkin noin 10 km välimatkan säteellä kaatopaikasta sen hyödyntäminen olisi mahdollista. Työn laskelmien mukaan Suomessa hukkaan poltetulla kaatopaikkakaasulla voitaisiin kuivata noin 250 tuhatta tonnia lietettä vuosittain.

Lämmöntalteenoton tuotteistus, kannattavuus ja riskit vaneriteollisuudessa

Viilunkuivaus vaneriteollisuudessa on energiaintensiivinen prosessi, josta syntyvä hukkalämpö kannattaa ottaa talteen ja hyödyntää. Työ käsittelee erilaisten lämmöntalteenottovariaatioiden tuotteistusta ja kannattavuutta, sekä sisältää laitteiston riskianalyysin. Aiemman asiakaskohtaisen räätälöinnin sijaan, laitteiston modulaarinen tuoterakenne on otettava tuotteistuksen lähtökohdaksi. Modulaarisen tuoterakenteen ansiosta erilaisiin asiakastarpeisiin pystytään vastaamaan aiempaa tehokkaammin, kiitos erilaisten variaatioiden. Standardien ja yhtenäisten rajapintojen myötä muun muassa suunnittelua, projektinhoito ja myyntiä saadaan tehostettua. Lämmöntalteenottoratkaisuille luodaan kolme eri varustelutasoa: perus, korkea ja luksus. Näillä eri varianteilla pystytään vastamaan entistä kattavammin eri markkina-alueiden asiakastarpeisiin. Kannattavuuslaskelmat todistavat, että lämmöntalteenoton avulla saadaan merkittäviä energiasäästöjä ja eri laitteistovariaatiot maksavat itsensä erittäin nopeasti takaisin, vaikka esimerkiksi sähköenergian hinta nousisi radikaalisti. Lämmöntalteenoton voidaankin katsoa olevan aina erittäin kannattavaa. Laitteistosta on tunnistettu myös tekniset riskit, joihin on puututtava välittömästi sekä lukuisia toimenpide-ehdotuksia, joiden avulla laitteiston tuomintaa voidaan tehostaa ja muuttaa turvallisemmaksi. Riskianalyysi antaa myös suuntaviivoja tuotteistukselle sekä laitteiston huolto- ja käyttöohjeistolle.

EDTA- and DTPA-functionalized silica gel and chitosan adsorbents for the removal of heavy metals from aqueous solutions

Adsorbents functionalized with chelating agents are effective in removal of heavy metals from aqueous solutions. Important properties of such adsorbents are high binding affinity as well as regenerability. In this study, aminopolycarboxylic acid, EDTA and DTPA, were immobilized on the surface of silica gel, chitosan, and their hybrid materials to achieve chelating adsorbents for heavy metals such as Co(II), Ni(II), Cd(II), and Pb(II). New knowledge about the adsorption properties of EDTA- and DTPA-functionalizedadsorbents was obtained. Experimental work showed the effectiveness, regenerability, and stability of the studied adsorbents. Both advantages and disadvantages of the adsorbents were evaluated. For example, the EDTA-functionalized chitosan-silica hybrid materials combined the benefits of the silica gel and chitosan while at the same time diminishing their observed drawbacks. Modeling of adsorption kinetics and isotherms is an important step in design process. Therefore, several kinetic and isotherm models were introduced and applied in this work. Important aspects such as effect of error function, data range, initial guess values, and linearization were discussed and investigated. The selection of the most suitable model was conducted by comparing the experimental and simulated data as well as evaluating the correspondence between the theory behind the model and properties of the adsorbent. In addition, modeling of two-component data was conducted using various extended isotherms. Modeling results for both one- and twocomponent systems supported each other. Finally, application testing of EDTA- and DTPA-functionalized adsorbents was conducted. The most important result was the applicability of DTPA-functionalized silica gel and chitosan in the capturing of Co(II) from its aqueous EDTA-chelate. Moreover, these adsorbents were efficient in various solution matrices. In addition, separation of Ni(II) from Co(II) and Ni(II) and Pb(II) from Co(II) and Cd(II) was observed in two- and multimetal systems. Lastly, prior to their analysis, EDTA- and DTPA-functionalized silica gels were successfully used to preconcentrate metal ions from both pure and salty waters

Immobilization of Burkholderia cepacia Lipase: Kinetic Resolution in Organic Solvents, Ionic Liquids and in Their Mixtures

Immobilization of Burkholderia cepacia Lipase: Kinetic Resolution in Organic Solvents, Ionic Liquids and in Their Mixtures Biocatalysis opens the door to green and sustainable processes in synthetic chemistry allowing the preparation of single enantiomers, since the enzymes are chiral and accordingly able to catalyze chemical reactions under mild conditions. Immobilization of enzymes enhances process robustness, often stabilizes and activates the enzyme, and enables reuse of the same enzyme preparation in multiple cycles. Although hundreds of variations of immobilization methods exist, there is no universal method to yield the highly active, selective and stable enzyme catalysts. Therefore, new methods need to be developed to obtain suitable catalysts for different substrates and reaction environments. Lipases are the most widely used enzymes in synthetic organic chemistry. The literature part together with the experimental part of this thesis discusses of the effects of immobilization methods mostly used to enhance lipase activity, stability and enantioselectivity. Moreover, the use of lipases in the kinetic resolution of secondary alcohols in organic solvents and in ionic liquids is discussed. The experimental work consists of the studies of immobilization of Burkholderia cepacia lipase (lipase PS) using three different methods: encapsulation in sol-gels, cross-linked enzyme aggregates (CLEAs) and supported ionic liquids enzyme catalysts (SILEs). In addition, adsorption of lipase PS on celite was studied to compare the results obtained with sol-gels, CLEAs and SILEs. The effects of immobilization on enzyme activity, enantioselectivity and hydrolysis side reactions were studied in kinetic resolution of three secondary alcohols in organic solvents, in ionic liquids (ILs), and in their mixtures. Lipase PS sol-gels were shown to be active and stable catalysts in organic solvents and solvent:IL mixtures. CLEAs and SILEs were highly active and enantioselective in organic solvents. Sol-gels and SILEs were reusable in several cycles. Hydrolysis side reaction was suppressed in the presence of sol-gels and CLEAs.

Recovery and refining of manganese as by-product from hydrometallurgical processes

The consumption of manganese is increasing, but huge amounts of manganese still end up in waste in hydrometallurgical processes. The recovery of manganese from multi-metal solutions at low concentrations may not be economical. In addition, poor iron control typically prevents the production of high purity manganese. Separation of iron from manganese can be done with chemical precipitation or solvent extraction methods. Combined carbonate precipitation with air oxidation is a feasible method to separate iron and manganese due to the fast kinetics, good controllability and economical reagents. In addition the leaching of manganese carbonate is easier and less acid consuming than that of hydroxide or sulfide precipitates. Selective iron removal with great efficiency from MnSO4 solution is achieved by combined oxygen or air oxidation and CaCO3 precipitation at pH > 5.8 and at a redox potential of > 200 mV. In order to avoid gypsum formation, soda ash should be used instead of limestone. In such case, however, extra attention needs to be paid on the reagents mole ratios in order to avoid manganese coprecipitation. After iron removal, pure MnSO4 solution was obtained by solvent extraction using organophosphorus reagents, di-(2-ethylhexyl)phosphoric acid (D2EHPA) and bis(2,4,4- trimethylpentyl)phosphinic acid (CYANEX 272). The Mn/Ca and Mn/Mg selectivities can be increased by decreasing the temperature from the commonly used temperatures (40 –60oC) to 5oC. The extraction order of D2EHPA (Ca before Mn) at low temperature remains unchanged but the lowering of temperature causes an increase in viscosity and slower phase separation. Of these regents, CYANEX 272 is selective for Mn over Ca and, therefore, it would be the better choice if there is Ca present in solution. A three-stage Mn extraction followed by a two-stage scrubbing and two-stage sulfuric acid stripping is an effective method of producing a very pure MnSO4 intermediate solution for further processing. From the intermediate MnSO4 some special Mn- products for ion exchange applications were synthesized and studied. Three types of octahedrally coordinated manganese oxide materials as an alternative final product for manganese were chosen for synthesis: layer structured Nabirnessite, tunnel structured Mg-todorokite and K-kryptomelane. As an alternative source of pure MnSO4 intermediate, kryptomelane was synthesized by using a synthetic hydrometallurgical tailings. The results show that the studied OMS materials adsorb selectively Cu, Ni, Cd and K in the presence of Ca and Mg. It was also found that the exchange rates were reasonably high due to the small particle dimensions. Materials are stable in the studied conditions and their maximum Cu uptake capacity was 1.3 mmol/g. Competitive uptake of metals and acid was studied using equilibrium, batch kinetic and fixed-bed measurements. The experimental data was correlated with a dynamic model, which also accounts for the dissolution of the framework manganese. Manganese oxide micro-crystals were also bound onto silica to prepare a composite material having a particle size large enough to be used in column separation experiments. The MnOx/SiO2 ratio was found to affect significantly the properties of the composite. The higher the ratio, the lower is the specific surface area, the pore volume and the pore size. On the other hand, higher amount of silica binder gives composites better mechanical properties. Birnesite and todorokite can be aggregated successfully with colloidal silica at pH 4 and with MnO2/SiO2 weight ratio of 0.7. The best gelation and drying temperature was 110oC and sufficiently strong composites were obtained by additional heat-treatment at 250oC for 2 h. The results show that silica–supported MnO2 materials can be utilized to separate copper from nickel and cadmium. The behavior of the composites can be explained reasonably well with the presented model and the parameters estimated from the data of the unsupported oxides. The metal uptake capacities of the prepared materials were quite small. For example, the final copper loading was 0.14 mmol/gMnO2. According to the results the special MnO2 materials are potential for a specific environmental application to uptake harmful metal ions.

Astringent Food Compounds and Their Interactions with Taste Properties

Astringency is traditionally thought to be induced by plant tannins in foods. Because of this current research concerning the mechanism of astringency is focused on tannin‐protein interactions and thus on precipitation, which may be perceived by mechanoreceptors. However, astringency is elicited by a wide range of different phenolic compounds, as well as, some non‐phenolic compounds in various foods. Many ellagitannins or smaller compounds that contribute to astringent properties do not interact with salivary proteins and may be directly perceived through some receptors. Generally, the higher degree of polymerization of proanthocyanidins can be associated with more intense astringency. However, the astringent properties of smaller phenolic compounds may not be directly predicted from the structure of a compound, although glycosylation has a significant role. The astringency of organic acids may be directly linked to the perception of sourness, and this increases along with decreasing pH. Astringency can be divided into different sub‐qualities, including even other qualities than traditional mouth‐drying, puckering or roughing sensations. Astringency is often accompanied by bitter or sour or both taste properties. The different sub‐qualities can be influenced by different astringent compounds. In general, the glycolysation of the phenolic compound results in more velvety and smooth mouthdrying astringency. Flavonol glycosides and other flavonoid compounds and ellagitannins contribute to this velvety mouthdrying astringency. Additionally, they often lack the bitter properties. Proanthocyanidins and phenolic acids elicit more puckering and roughing astringency with some additional bitter properties. Quercetin 3‐O‐rutinoside, along with other quercetin glycosides, is among the key astringent compounds in black tea and red currants. In foods, there are always various other additional attributes that are perceived at the same with astringency. Astringent compounds themselves may have other sensory characteristics, such as bitter or sour properties, or they may enhance or suppress other sensory properties. Components contributing to these other properties, such as sugars, may also have similar effects on astringent sensations. Food components eliciting sweetness or fattiness or some polymeric polysaccharides can be used to mask astringent subqualities. Astringency can generally be referred to as a negative contributor to the liking of various foods. On the other hand, perceptions of astringent properties can vary among individuals. Many genetic factors that influence perceptions of taste properties, such as variations in perceiving a bitter taste or variations in saliva, may also effect the perception of astringency. Individuals who are more sensitive to different sensations may notice the differences between astringent properties more clearly. This may not have effects on the overall perception of astringency. However, in many cases, the liking of astringent foods may need to be learned by repetitive exposure. Astringency is often among the key sensory properties forming the unique overall flavour of certain foods, and therefore it also influences whether or not a food is liked. In many cases, astringency may be an important sub‐property suppressed by other more abundant sensory properties, but it may still have a significant contribution to the overall flavour and thus consumer preferences. The results of the practical work of this thesis show that the astringent phenolic compounds are mostly located in the skin fractions of black currants, crowberries and bilberries (publications I–III). The skin fractions themselves are rather tasteless. However, the astringent phenolic compounds can be efficiently removed from these skin fractions by consecutive ethanol extractions. Berries contain a wide range of different flavonol glycosides, hydroxycinnamic acid derivatives and anthocyanins and some of them strongly contribute to the different astringent and bitterness properties. Sweetness and sourness are located in the juice fractions along with the majority of sugars and fruit acids. The sweet and sour properties of the juice may be used to mask the astringent and bitterness properties of the extracts. Enzymatic treatments increase the astringent properties and fermented flavour of the black currant juice and decrease sweetness and freshness due to the effects on chemical compositions (IV). Sourness and sweetness are positive contributors to the liking of crowberry and bilberry fractions, whereas bitterness is more negative (V). Some astringent properties in berries are clearly negative factors, whereas some may be more positive. The liking of berries is strongly influenced by various consumer background factors, such as motives and health concerns. The liking of berries and berry fractions may also be affected by genetic factors, such as variations in the gene hTAS2R38, which codes bitter taste receptors (V).

Sellutehtaan vedenkäytön vähentäminen

Työn tarkoituksena oli etsiä mahdollisia kohteita sellutehtaan veden käytön vähen-tämiseksi. Analyysien avulla selvitettiin voidaanko havaittujen kohteiden tällä hetkellä menetettyjä vesivirtoja käyttää uudelleen. Lopuksi arvioitiin miten kierrä-tettävät vedet vaikuttaisivat raakaveden laatuun, mikäli ne yhdistettäisiin tämän joukkoon. Veden käytön vähentämiskohteita etsittiin tutkimalla tehtaan prosessi-kaavioita osastokohtaisesti sekä selvittämällä näin havaittuja kohteita osastoilla. Työn kokeellinen osa koostui vesianalyyseistä. Vesianalyyseissä määritettiin seu-raavat arvot sellutehtaalle tulevasta vedestä: sameus (FTU), kiintoaine, sähkönjoh-tavuus, pH, CODCr, BOD7ATU, kokonaisfosfori P, Mn, Cl, K, Ca, Mg ja AOX. Nämä tehtiin valituista kohteista havaituista tällä hetkellä tehtaalta pois johdetuista mutta mahdollisesti kierrätettävistä vesistä. Työn tuloksien perusteella havaittiin, että seuraavissa tarkasteluun valituissa koh-teissa vedet olivat hyvin puhtaita ja talteen otettavia kierrätykseen. Näitä olivat savukaasupesurin vedet, sekundäärilauhdesäiliön vedet sekä tiivistevedet. Haih-duttamon lämminvesisäiliön sekä kuivauskone 4 kiertovesitornin vedet olivat hieman likaantuneet mutta hyvin kierrätettävissä. Koivulinjan D0-vaiheen, havu-linjan D1-vaiheen sekä kuivauskone 4 lajittamon vesivirtoja ei likaantumisen vuoksi kannattanut kerätä hyötykäyttöön.

Structural and operational optimisation : applications in energy systems

In this work mathematical programming models for structural and operational optimisation of energy systems are developed and applied to a selection of energy technology problems. The studied cases are taken from industrial processes and from large regional energy distribution systems. The models are based on Mixed Integer Linear Programming (MILP), Mixed Integer Non-Linear Programming (MINLP) and on a hybrid approach of a combination of Non-Linear Programming (NLP) and Genetic Algorithms (GA). The optimisation of the structure and operation of energy systems in urban regions is treated in the work. Firstly, distributed energy systems (DES) with different energy conversion units and annual variations of consumer heating and electricity demands are considered. Secondly, district cooling systems (DCS) with cooling demands for a large number of consumers are studied, with respect to a long term planning perspective regarding to given predictions of the consumer cooling demand development in a region. The work comprises also the development of applications for heat recovery systems (HRS), where paper machine dryer section HRS is taken as an illustrative example. The heat sources in these systems are moist air streams. Models are developed for different types of equipment price functions. The approach is based on partitioning of the overall temperature range of the system into a number of temperature intervals in order to take into account the strong nonlinearities due to condensation in the heat recovery exchangers. The influence of parameter variations on the solutions of heat recovery systems is analysed firstly by varying cost factors and secondly by varying process parameters. Point-optimal solutions by a fixed parameter approach are compared to robust solutions with given parameter variation ranges. In the work enhanced utilisation of excess heat in heat recovery systems with impingement drying, electricity generation with low grade excess heat and the use of absorption heat transformers to elevate a stream temperature above the excess heat temperature are also studied.