One of the major cost factors in mechanical pulp production is the electrical energy input. Much of the research in this field has therefore been devoted to an understanding of the mechanisms in the refining process and, consequently, to find ways of reducing the electrical energy consumption. Shear and compression are probably the main types of fibre deformation occurring in refiners for collapsing and fibrillating the fibres into a suitable pulp. In current refiners, the repeated mechanical action of the bars on the fibres consumes large amounts of energy in a treatment of mechanical fibres that is almost random. Fundamental studies of the deformation of wood have indicated that a combination of shearing and compression forces is highly beneficial in terms of fibre deformation with a low energy demand. Pure compression is able to permanently deform the fibre but requires a substantial amount of work, while pure shearing, although being much less energy demanding, does not lead to any permanent deformations. A more suitable application of the shear and compression forces on the wood fibres during the refining process could be a way to develop fibres at a lower energy demand. These ideas have been studied in this work trying to find new ways of saving energy in the mechanical pulping process. The first paper in this thesis discusses the way of producing wood shavings and the introduction of shear/compression deformations in these, as well as the potential benefits of using them instead of wood chips as raw material for TMP production. With the shaving process, high deformations in the wood cells were achieved by the shear and compression forces. This led to energy savings of about 25% at a given tensile index, when compared to traditional chips. The quality of the pulp produced from wood shavings was found to be better than that of the pulp produced from wood chips, when it came to strength properties (except for tear index) and optical properties at comparable energy levels. Another way of reducing energy consumption in refining involving a limited shear combined with compression forces for the mechanical treatment of both wood chips and coarse fibres was also studied. This work shows that such a kind of treatment resulted in a high degree of fibre collapse at low energy demands. The thick-walled transition fibres could even be permanently deformed. Furthermore, refining trials, utilising shear and compression pre-treated chips, showed that the strength properties, except for tear index, along with the optical properties of a TMP could be improved and the electrical energy consumed could be reduced by approx. 100 kWh/tonne, when compared to untreated chips. The results from the pilot trials described in this work could be used as a starting point for further implementation in the industry, in order to identify the most efficient way of producing mechanical pulp with a lower consumption of electrical energy. / QC 20101119

Due to environmental concerns and to the limited amount of fossil fuel in the world theinterest in using renewable material has been and will continue to be on the rise. With theincreasing demand for renewable materials such as bio-based fibers, the research aroundnatural fibers is intensifying. Abaca (Musa Texitilis Nee) is a plant endemic to the Philippineswhich is claimed to contain the strongest natural fiber in the world 1. However, no thoroughresearch on performing tensile strength test on single abaca fibers/cells has been found. Byperforming tensile strength test on the single abaca fibers and relate this will provide freshdata about the single abaca fiber strength that can be compared with other natural fibers.This can later be a reference tool in order to find the optimal fiber for the product to be made. The purpose of this study is to develop a methodology for performing tensile strength testson single abaca fibers with the major objective to relate the tensile strength and E-modulusof the fibers with their microfibrillar angle (MFA). The research was done by using Abaca(grade S2) from Camarines Sur (Philippines) that was chemically disintegrated in order toobtain single fibers. The single fibers were mounted to a custom made paper frame for thetensile strength test performed by an Instron 5944. The MFA of each fiber was also retrievedusing an optical microscope with a polarized filter. The research showed an indication of aninversely proportional relation between MFA and tensile strength of the fibers. According tothe results, the E-modulus of the single abaca fiber was almost constant, independently onthe MFA of the fiber. / The purpose of this study is to do a broad map out of the abaca industry in the Philippines. Furthermore, the study aims to provide an overview of the abaca industry as a tool for finding ways to optimize the fiber production and to find suggestions on how to make a bigger share of the profit from the abaca products to stay by the farmers in the Philippines. The objectives are therefore also focused on describing the way the abaca plant is cultivated, harvested, processed, and further distributed from the farms. Also, the objectives are to describe the abaca supply and demand situation along with identifying challenges for abaca production. Today the outmoded abaca production in the Philippines is experiencing a productivity loss which makes the farmers' incomes unnecessarily low. Important factors that, by this study, have been identified affecting the low productivity and profit are lack of proper farming management, distribution and unoptimized usage of the fibers. A big share of the abaca fibers produced is also being exported. This means that the raw fibers are being made into high-value products abroad and hence the profit to be made is dislocated further from the farmers with low means of improving their standard of living. The study has been performed by doing a literature study complemented with interviews and visits to abaca farmers and other stakeholders within the abaca industry.

Syftet med denna studie är att undersöka inverkan av förbehandlingar på ljushetsstabiliteten av Northern Bleached Softwood Kraft (NBSK) som har blekts enligt (OO) (OP) D/Dn (PO) bleksekvensen. Effekten av förbehandling med xylanas (X), mild sur (A), DTPA (Q) samt ett kombinerad DTPA- & xylanassteg (Q+X) har studerats.  Resultaten indikerar att Q+X förbehandlingen var mest effektiv i minskningen av skadliga metalljoner i massan. Den Q+X förbehandlade massan hade dessutom lägst kappa och högst ljushetsvärde bland förbehandlingarna. Kemisk sammansättningsanalys av de förbehandlade massorna visar vidare att den Q+X förbehandlingen ledde till den högsta minskningen av såväl xylan som lignin. Det milda A förbehandlingen var inte effektivt för att avlägsna alla viktiga skadliga metalljoner och visade ingen effekt på reduktionen av xylan eller lignin. Den X behandlade massan visade ingen förmåga att ta bort metaller och är därför ofördelaktigt.  Q och Q+X förbehandlade massaströmmar har blekts vidare för att studera effekterna av dessa förbehandlingar på den slutliga massakvaliteten samt för att jämföra ett konventionellt klordioxidsteg (D) och en nästan neutral pH klordioxidsteg (Dn). Resultaten bekräftar att Dn-steget ledder till en reducerad grad av AOX.  Ljusheten direkt efter klordioxidsteget är vidare högre för de Dn-behandlade massorna, men processen är begränsad med avseende på ljushetsstabilitet, vilket är en viktig nackdel.  Q+X (OP) D (PO) blekningssekvensen visade den högsta ljushetsstabilitet, medan den Q+X (OP) Dn (PO) blekningssekvensen visade ingen förbättring jämfört med Q (OP) Dn (OP) blekningssekvensen. Slutsatsen är att den enzymatisk medförda kvalitetsförbättringen inte räcker för att kompensera för bristerna i ett Dn-steg. / This is a study on Northern Bleached Softwood Kraft (NBSK) and the (OO) (OP) D/Dn (PO) bleaching sequence. The effects of a xylanase (X), mild acidic (A), DTPA (Q), and a combined DTPA & xylanase (Q+X) pre-treatments have been studied. The results indicate that the Q+X pre-treatment most effectively reduced the presence of harmful metal ions in the pulp. The Q+X pre-treated pulp furthermore yielded the lowest kappa number and highest brightness values among the pre-treatments tested. Chemical analysis of this pulp also shows the highest reduction in xylans and lignin. The mild A stage was ineffective in removing all harmful metal ions and showed no effect on the reduction of xylans or lignin. The X stage cannot meanwhile remove metals and is thus disadvantageous. Subsequently, the Q+X pre-treated pulp as well as a Q-treated pulp stream were further bleached to study the effects of these pre-treatments on the final pulp quality as well as to compare these streams of pulp bleached using a conventional chlorine dioxide stage (D) and a near neutral pH chlorine dioxide (Dn) stage. The results confirmed that the Dn stage causes a reduced degree of AOX in the effluent. Furthermore, the brightness directly after the chlorine dioxide stage is higher for the Dn-treated pulps but the process is limited in brightness stability which is a significant drawback. The Q+X (OP) D (PO) bleaching sequence showed the highest brightness stability while the Q+X (OP) Dn (PO) bleaching sequence displayed no improvement over the Q (OP) Dn (OP) bleaching sequence. The conclusion can be made that the enzymatic boost in bleaching is not enough to compensate for the shortcomings of a Dn stage.

Munksunds pappersbruk är ett integrerat massa- och pappersbruk som består av två fiberlinjer, en barr- och en lövlinje där båda kokarna är kontinuerliga med efterföljande tvättsteg. En kartering av COD (eng. Chemical Oxygen Demand) och natrium utfördes för båda linjerna för att utvärdera tvätteffektiviteten. COD anger hur mycket syre som krävs för att bryta ned det kvarvarande organiska materialet och natrium används som en indikator på tvättförlusten av kokkemikalierna. Karteringen utfördes genom att analysera in- och utgående flöden vid varje tvättsteg, exklusive kokarna. En förenklad metod användes, där tre flöden analyserades och den fjärde beräknades genom flödes- och massbalanser. Modellen som användes för att beskriva tvätteffektiviteten för respektive utrustning var tvättutbytet Y, som erhölls genom en massbalans. Studien visade att halten COD och Natrium minskar mest från början för respektive linje och når ett gränsvärde runt 8,2 kg COD/adt och 6,6 kg Na/adt för barrlinjen, respektive 8,5 kg COD/adt och 4,8 kg Na/adt för lövlinjen, där ytterligare substans inte kan tvättas bort. Båda linjerna tvättar likvärt med avseende på COD, men lövlinjen tvättar bättre med avseende på natrium. I det sista tvättsteget hade båda fiberlinjerna eliminerat 98% av den inkommande COD-mängden med massan från kokarna. Vidare hade barrlinjen eliminerat 86% och lövlinjen 93% med avseende på natrium i det sista tvättsteget. Utvärderingen av de olika tvättutrustningarna visade att DD-filtret i lövlinjen var effektivast både med avseende på COD och natrium, följt av PO-pressen. På barrlinjen var filter 1 mest effektivt med avseende på COD och natrium. / A mapping of COD (Chemical oxygen demand) and sodium will be done to evaluate the different washing steps. COD describe the amount of oxygen needed to dissolve the organic matter left in the pulp and sodium is used as an indicator of the washing loss of the cooking chemicals. The in- and outgoing streams of the washing steps was analyzed to examine the efficiency. A simplified method was applied where three streams were analyzed and the fourth was calculated through flow-and mass balances. The model used to describe the wash efficiency in this study was the wash yield, which can be obtained by mass balances. The study showed that the content of COD and sodium decreased most in the beginning and reaches a limit value of 8,2 kg COD/adt and 6,6 kg Na/adt in the softwood pulp line and 8,5 kg COD/adt and 4,8 kg Na/adt in the soft wood pulp line, where no more content could be removed. Both pulp lines washed efficient with aspect of COD, but the hardwood pulp line washed more efficient in the aspect of natrium compared to the softwood pulp line. In the last washing step, both pulp lines had removed 98% of the ingoing COD from the digester. With aspect to natrium the softwood pulp line had removed 86% and the hardwood pulp line 93% in the last washing step. The evaluation of the different washing equipment showed that the DD-filter in the hardwood pulp line was the most efficient with aspect of both COD and Sodium, followed by the PO-press. In the softwood pulp line, filter 2 was the most efficient regarding both COD and Sodium. The flow- and mass balances turned out to be complicated at some of the washing steps, especially around the Q1-press in the hardwood pulp line and press 1-3 and filter 2 in the softwood pulp line. The reason for this could be that different functional chemicals are added before the Q1-press, which was not considered in this study, additional causes could be unidentified flows that affect the balances. The study was limited to only analyze three streams and calculate the fourth, an analyze of all the streams would give a more accurate result. However, the study provides a good overview of the wash efficiency in the pulp mill.

Paper is used in a wide range of applications, each of which has specific requirements on mechanical and surface properties. The role of paper strength on paper performance is still not well understood. This work addresses the mechanical properties of paper by utilizing fiber network simulation and consists of two parts.In the first part, we use a three-dimensional model of a network of fibers to describe the fracture process of paper accounting for nonlinearities at the fiber level (material model and geometry) and bond failures. A stress-strain curve of paper in tensile loading is described with the help of the network of dry fibers; the parameters that dominate the shape of this curve are discussed. The evolution of network damage is simulated, the results of which are compared with digital speckle photography experiments on laboratory sheets. It is concluded that the original strain inhomogeneities due to the structure are transferred to the local bond failure dynamics. The effects of different conventional and unconventional bond parameters are analyzed. It has been shown that the number of bonds in paper is important and that the changes in bond strength influence paper mechanical properties significantly.In the second part, we proposed a constitutive model for a fiber suitable for cyclic loading applications. We based the development of the available literature data and on the detailed finite-element model of pulp fibers. The model provided insights into the effects of various parameters on the mechanical response of the pulp fibers. The study showed that the change in the microfibril orientation upon axial straining is mainly a geometrical effect and is independent of material properties of the fiber as long as the deformations are elastic. Plastic strains accelerate the change in microfibril orientation. The results also showed that the elastic modulus of the fiber has a non-linear dependency on a microfibril angle,with elastic modulus being more sensitive to the change of microfibril angle around small initial values of microfibril angles. These effects were incorporated into a non-linear isotropic hardening plasticity model for beams and tested in a fiber network in cycling loading application model, using the model we estimated the level of strains that fiber segments accumulate at the failure point in a fiber network.The main goal of this work is to create a tool that would act as a bridge between microscopic characterization of fiber and fiber bonds and the mechanical properties that are important in the papermaking industry. The results of this work provide a fundamental insight on mechanics of paper constituents in tensile as well as cyclic loading. This would eventually lead to a rational choice of raw materials in paper manufacturing and thus utilizing the environment in a balanced way. / <p>QC 20130605</p>

Fluffmassa är ett förnybart material bestående av cellulosafiber som utvinns under massakokning. Dessa fiber används för att tillverka olika absorberande produkter som till exempel servetter. Fluffmassa används även för att tillverka absorptionskärnor i damhygienprodukter, inkontinensprodukter och blöjor. Vissa av dessa absorptionskärnor (speciellt i ultratunna bindor) tillverkas med airlaid. Airlaid är en tillverkingsteknik som ger fiberstrukturer med slumpmässig orientering genom att applicera ett undertryck.  Syftet med detta examensarbete var att utveckla metoder för att tillverka servetter och absorptionskärnor till damhygienprodukter i laboratoriemiljö genom att använda en airlaid maskin i laboratorieskala. Detta utfördes genom att analysera viktiga egenskaper som exempelvis ytvikt, tjocklek, densitet, böjlängd och förmågan att absorbera vätska i kommersiella servetter och absorptionskärnor inom damhygien. Även dragprov och SEM-analys utfördes. Resultatet från dessa analyser användes som ett riktvärde under metodutvecklingen.  Två metoder utvecklades - en för att tillverka en servettstruktur och en för att tillverka en absorptionskärna för damhygien. De olika tillverkningsstegen inkluderar defibrering, formering, pressning, prägling, latexsprayning samt härdning. Båda strukturerna tillverkades, och dess egenskaper analyserades och jämfördes med de kommersiella produkterna. Analyserna visade att de utvecklade metoderna genererade struktuer vars ytvikt stämde väl överrens med de kommersialla produkterna. Strukturerna var dock tjockare och hade en lägre densitet än de kommmersiella produkterna. Den minskade densiteten påverkade förmodligen resultatet från de andra analyserna som utfördes i detta projekt. Servettstrukturen hade en lägre böjlängd än de kommersiella servetterna och damhygienstrukturen hade bättre absorption än de kommersiella produkterna.  Båda strukturerna hade en ytfinish som överensstämmde väl med de kommersiella produkterna. Dock visade SEM-analysen att latex saknades i mitten av de båda tillverkade strukturerna. / Fluff pulp is a renewable material consisting of pure cellulose fibers which are obtained during pulping. These fibers are commonly used to form Airlaid-nonwoven products such as napkins and wipes. Fluff pulp is also used in absorbent cores in femcare products, incontinence products and diapers. Some of these absorbent core structures (especially in ultrathin pads) are produced through airlaid. Airlaid is a manufacturing technique which forms a randomly oriented fiber structure by using an applied suction.  This degree project aimed at developing methods for producing napkins and femcare absorbent cores on a laboratory scale by using an airlaid former. Important properties such as grammage, thickness, density, bending length and absorption capacity were therefore measured on commercial napkins and femcare absorbent cores. Other analyses which were performed include tensile testing and SEM. Findings from these analyses were then used as a target reference during the method development.  Two methods were developed; one for producing a napkin structure and one for producing a femcare absorbent core structure. The different manufacturing steps included fiber defiberization, sample formation, pressing, embossing, latex spraying and curing. Napkin structures and femcare absorbent core structures were produced by using the developed methods, and their properties were analyzed and compared with the commercial products.  Analysis showed that the developed methods generated structures with grammages that corresponded well with the grammages in the commercial products. However, both developed structures were thicker and had lower density than the commercial products. This decreased density probably influenced the results in other analyses performed in this project. The developed napkin structure had a shorter bending length compared to the commercial napkins and the developed femcare structure had a better absorption capacity compared to the commercial femcare absorbent cores. Both developed structures obtained nice surface finish which corresponded well with the surface finish in the commercial products. However, SEM analysis indicated that no latex managed to reach the center in the developed structures.

Delignifiering under sulfat koket innefattar både kemisk nedbrytning och fysisk upplösning av lignin, för vilket närvaron av oorganiska salter, oorganiska anjoner samt oorganiska katjoner (sammantaget benämnda som "Non-process elements", NPEs på engelska) kan ha inverkan på delignifieringens hastighet. Tidigare studier har funnit att ved med högt kalciuminnehåll är svårdelignifierad och att kalcium har potentiell inverkan på ligninlöslighet och kappatal. Att avlägsna kalcium från ved är svårt, men vissa studier har visat att detta kan motverka ovannämnda2(4)inverkan och öka delignifieringen. Denna studie har studerat effekten av kalcium under delignifieringen på fyra prover av Eucalyptus dunnii tagna från olika marktyper, åldrar, kalciumhalt samt geografisk plats (i Uruguay). Målet har varit att undersöka kalciumets inverkan under delignifieringen och dess effekt på massautbytet. Fyra satser av vardera vedmat erial kokades i stålautoklaver med följande parametrar: 18 % effektiv alkali, 35 % sulfiditet, 1 h impregnering vid 110 °C, 2,75 h, 3 h, 3,25 h respektive 3,5 h koktider (för vardera sats) vid 145 °C. Provet med den högsta kalciumhalten om 4668 mg/kg kunde dock inte delignifieras, vare sig vid dessa kokparametrar eller vid en temperaturökning till 155 °C och en resulterande H-faktor på 735 enheter – motsvarande 7 h koktid vid 145 °C – och analyserades inte vidare i studien. Resultaten visar på en negativ effekt från kalcium avseende både delignifieringshastighet och utbyte: Eucalyptus med en lägre kalciumhalt på 705 mg/kg gav massa med kappatal 13 efter kokning, medan eucalyptus med 1500 mg/kg kalcium efter samma kokning gav massa med kappatal 17. Motsvarande utbyte för dessa massor var 48 % för provet med lägre kalciumhalt och 46 % för provet med högre kalciumhalt. Kvantifiering av modifierat kappa och uronsyror bekräftade att ovannämnda effekter inte berodde på inverkan från hexennuronsyra i massan. / Delignification during sulphate cooking involves both chemical degradation and physical solubilization of lignin where the presence of non-process elements (NPEs), inorganic salts, anions or cations in the process could affect the rate of delignification. Previous studies also indicate that wood with higher calcium content is challenging to delignify which would affect the lignin solubility and increase kappa number. Besides, the removal of calcium from Eucalyptus is difficult. However, some study suggests that removal of calcium before the process increases the rate of delignification. This work studies the effect of calcium in four Eucalyptus dunnii samples of different soil type, age, different calcium content and Uruguayan geographical areas during the delignification process. The aim is to study the influence of calcium during the delignification in kraft cooking and its effects on pulp yield in Eucalyptus dunnii. Four batches of each material were cooked in a steel autoclaves with the following parameters: 18% effective alkali, 35% sulphidity, 1 h impregnation at 110 ° C, 2.75 h, 3 h, 3.25 h and 3.5 h cooking times, respectively (for each batch) at 145 ° C. Besides, sample with Ca-4668 mg/kg were not able to defibrate at common cooking conditions and even after altering the cooking conditions to higher temperature 155℃, H-Factor to be 735 (cooking time of 7 hours) and were not analyzed further in the study. Results suggest that there is a detrimental influence of calcium on delignification during the kraft cooking process, and it also affects the pulp yield in Eucalyptus dunnii. Eucalyptus with a lower calcium content of 705 mg / kg gave pulp with kappa number 13 after cooking, while eucalyptus at 1500 mg / kg calcium after the same cooking time gave pulp with kappa number 17. Corresponding yield for these pulps were 48% for the lower calcium sample and 46% for the higher sample calcium content. A slower rate of delignification with higher kappa number and lower overall pulp yield are the results of higher calcium content in Eucalyptus dunnii. Quantification of modified kappa and uronic acids confirm that the effect of calcium on kappa is due to residual lignin and not by the presence of hexenuronic acids.

Thermal insulation materials made from natural fibrous materials, such as cellulose fibers, have advantages over others from a sustainability point of view. However, cellulosic materials are generally prone to mold and absorb moisture, and these have negative effects on the insulation properties, the durability of insulation materials, and interior air quality. In this thesis, cellulose-fiber-based insulation foams were prepared from bleached chemithermomechanical softwood pulp, and these foams showed promising thermal insulation properties and fungal resistance. Hydrophobic extractives were isolated from birch (Betula verrucosa) outer bark and used to improve the water resistance of the foams, which were impregnated in solutions of extractives and then dried. The modified foams showed greater water resistance, and the modification had no negative effects on the thermal insulation, fungal resistance, and compressive strength of the foams. Another potential problem with low density cellulosic thermal insulation materials is their poor reaction-to-fire properties. Cellulose-fiber-based insulation foams were prepared from formulations containing bleached chemithermomechanical softwood pulp and commercial fire retardants to improve the reaction of the foams to fire. Single-flame source test results showed that the foams containing 20% expandable graphite (20% EG) or 25% synergetic (25% SY) fire retardant had significantly improved reaction-to-fire properties and passed class E, which reflected that they can resist a small flame attack without substantial flame spreading for a short period according to EN 13501-1. Compared with the reference without any fire retardant, the peak heat release rate (Peak-HRR) of the 20% EG and 25% SY decreased by 62% and 39% respectively when the samples were subjected to a radiance heat flow of 25 kW m-2 in a Cone Calorimeter. The thesis demonstrates that it is possible to produce cellulose-fiber-based insulation materials with improved properties in terms of fungal, improved water resistance and reaction-to-fire properties. / <p>QC 20170428</p> / Energy-efficient cellulosic insulation products/panels for green building solutions

Paper making today is, to some extent, based on empirical knowledge. It is wellknown that fines, pH, charge and ion strength affect the manufacture of paper. One way of extending knowledge of the mechanisms of paper chemistry is to follow the trajectories of fines and additives in the paper suspension to gather information as to the manner in which they react. Four tracking algorithms adapted to the needs of this particular problem were implemented in order to track particles effciently. The tracking algorithms include two variants of the well-known "Lucas-Kanade algorithm" and template matching techniques based on cross-correlation and least squares matching. Although these techniques are similar in principle, the actual tracking can nevertheless differ; the Lucas-Kanade algorithms were found to be more invariant to noise, whereas the cross-correlation and least squares methods are more rapid to execute in Matlab. The tracking methods have been evaluated using a simulator to generate image sequences of synthetic particles moving according to Brownian motion. Tracking has also been evaluated on microscope images of real latex particles where the results have been compared to manual tracking. Tracking of both the simulated particles and the latex particles resulted in similar results when compared to known position and manual tracking, respectively. / Tillverkning av papper är till en viss del baserad på empirisk kunskap. Välkänt är att finmaterial, pH värde, laddning och jonstyrka påverkar de papperskemiska mekanismerna och därmed flertalet pappersegenskaper vid tillverkning av papper. En möjlighet att utveckla kunskaperna inom papperskemiska mekanismerar att studera finmaterial och additiv i en pappers suspension for att samla in informationom reaktionsmekanismer. Fyra trackningalgoritmer ar vidareutvecklade i syftet att möjliggöra studier kring papperskemiska mekanismer. Trackningalgoritmerna inkluderar två varianter av den välkända "Lucas-Kanade" algoritm och två template-baserade metoder: korskorrelation och minsta kvadratmetoden. Samtliga metoder bygger på samma princip, men trots detta kan resultaten från trackningen skilja mellan metoderna. Lucas-Kanade algoritmerna är mer oberoende av brus medan korskorrelationen och minsta kvadratmetoden exekveras snabbare i Matlab. Trackning metoderna utvärderades med hjälp av en simulator som genererar bildsekvenser av syntetiska partiklar med en Brownsk rörelse. Trackningen har även använts på mikroskopibilder av rörelsebanor på verkliga suspenderade latex partiklar, varvid trackningresultatet har jämförts med manuell trackning. De genererade bildsekvensernapa de simulerade partiklarna har kända rörelsebanor som är jämförbara med rörelsebanor for latex partiklarna.

One of the main interests in commercial methane production is to maximize the gas yield, and it is thus appealing to use material with relative high methane potential. However, such material often results in process instability whereas ammonia inhibition is common. Removal of ammonia through adsorption is a fairly unexplored method in the field of biogas production, and could prove to be cost-effective.The adsorption capacity of pulp fibres from the paper making industry were investigated through batch adsorption experiments. Additionally, the fibres effect on small scale batch digesters in terms of methane production and cellulase activity was explored. Overall, the adsorption capacity of the pulp fibres was low, whereas Kraft hardwood had the highest adsorption capacity in both an aqueous ammonium solution and digester fluid at 11±3 and 60±20 mg g-1, respectively. The initial total ammonium nitrogen concentration had the highest effect on the adsorption capacity with a positive correlation. The pulp fibres seemingly had no effect on the ammonia inhibited anaerobic digestion systems. However, the cellulase activity was higher after day 5 in the anaerobic digestion systems with a high ammonia concentration.In essence, the overall results showed that the adsorption of the fibres was relatively low and most likely not suitable as a material to prevent ammonia inhibition in an AD.