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This thesis presents some new techniques that were developedfor continuous chemical analysis of a paper furnish. First, ageneral background is presented, covering topics from theorigins of papermaking to present day. A short introduction topapermaking chemistry and a variety of presently availableon-line chemical analysers and measurement strategies are alsodiscussed. A method is described for the continuous fractionation of apaper furnish containing coarse fibres (&gt;10µm) in orderto obtain a sample for analytical purposes (Paper I). Aconsistent sample, containing a representative fraction of thedissolved and colloidal substances (DCS) present in the bulkfurnish, was achieved by preventing cake formation on a filtersurface. A combination of turbulent flow above a membranefilter, while continuously withdrawing a relatively low samplevolume, were key factors in the prevention of filterfouling. For the continuous flow-extraction of DCS, a technique isdescribed whereby the extracting solvent was injected at a highvelocity into a continuous flow of analyte (Paper II).Comparison with conventional flow extraction showed anextraction enhancement of up to 9 times for colloidaltriglycerides. To achieve a continuous determination of chemicalsubstances, a real-time fully automated colorimetric titrationapparatus was developed (Paper III&amp;IV). This was achievedby using a series of micro-machined mixing channels for thecontinuous flow of analyte, with a sequence of detection unitsand titrant addition points along the flowpath (Paper III). Afuzzy logiccontroller was implemented to continuously adaptfor changes in the sample concentration, providing thepossibility of titrating over two orders of magnitude in sampleconcentration with minimal loss of accuracy (Paper IV). Also, a system is presented whereby the filtration apparatus(Paper I) is combined with the titration device (Paper III&amp;IV) in order to continuously determine total charge (orcolloidal charge) of a paper furnish in real-time (Paper V).This was achieved by utilising a back-titration approach andselected examples are presented showing the dynamicinteractions between wood fibres and polyelectrolyte adsorptionat various conditions of pH and polyelectrolyte molecularweight. Finally, some suggestions for a more comprehensive wet-endchemical monitoring platform are discussed and the role of thepresent work in evaluated in this context. <b>Keywords:</b>Chemical monitoring, continuous flowextraction, cross-flow filtration, dissolved and colloidalcomponents, fuzzy-logic control, on-line system, pitchanalysis, polyelectrolyte titration, process control, samplework-up, titrimetric analysis.

<p>This thesis presents some new techniques that were developedfor continuous chemical analysis of a paper furnish. First, ageneral background is presented, covering topics from theorigins of papermaking to present day. A short introduction topapermaking chemistry and a variety of presently availableon-line chemical analysers and measurement strategies are alsodiscussed.</p><p>A method is described for the continuous fractionation of apaper furnish containing coarse fibres (>10µm) in orderto obtain a sample for analytical purposes (Paper I). Aconsistent sample, containing a representative fraction of thedissolved and colloidal substances (DCS) present in the bulkfurnish, was achieved by preventing cake formation on a filtersurface. A combination of turbulent flow above a membranefilter, while continuously withdrawing a relatively low samplevolume, were key factors in the prevention of filterfouling.</p><p>For the continuous flow-extraction of DCS, a technique isdescribed whereby the extracting solvent was injected at a highvelocity into a continuous flow of analyte (Paper II).Comparison with conventional flow extraction showed anextraction enhancement of up to 9 times for colloidaltriglycerides.</p><p>To achieve a continuous determination of chemicalsubstances, a real-time fully automated colorimetric titrationapparatus was developed (Paper III&IV). This was achievedby using a series of micro-machined mixing channels for thecontinuous flow of analyte, with a sequence of detection unitsand titrant addition points along the flowpath (Paper III). Afuzzy logiccontroller was implemented to continuously adaptfor changes in the sample concentration, providing thepossibility of titrating over two orders of magnitude in sampleconcentration with minimal loss of accuracy (Paper IV).</p><p>Also, a system is presented whereby the filtration apparatus(Paper I) is combined with the titration device (Paper III&IV) in order to continuously determine total charge (orcolloidal charge) of a paper furnish in real-time (Paper V).This was achieved by utilising a back-titration approach andselected examples are presented showing the dynamicinteractions between wood fibres and polyelectrolyte adsorptionat various conditions of pH and polyelectrolyte molecularweight.</p><p>Finally, some suggestions for a more comprehensive wet-endchemical monitoring platform are discussed and the role of thepresent work in evaluated in this context.</p><p><b>Keywords:</b>Chemical monitoring, continuous flowextraction, cross-flow filtration, dissolved and colloidalcomponents, fuzzy-logic control, on-line system, pitchanalysis, polyelectrolyte titration, process control, samplework-up, titrimetric analysis.</p>

Mikrosiebe stellen auf Grund ihrer Geometrie einen geringeren Strömungswiderstand im System dar und ermöglichen somit eine höhere Filtrationsgeschwindigkeit. Der Einsatz solcher Mikrosiebe anstelle herkömmlicher Membranen in Filtrationsprozessen kann deren Effizienz enorm steigern. Im Rahmen der Diplomarbeit wurden mittels partikelassistierter Benetzung hergestellte Mikrosiebe charakterisiert. Hierfür wurde zunächst ein Filtermodul für Kreuzstromfiltrationen entwickelt, welches anschließend in einen Versuchsaufbau integriert und charakterisiert wurde. Neben den Strömungswiderständen der rechteckigen Kanäle des Moduls wurde außerdem der Strömungswiderstand für Mikrosiebe einer Porengröße bestimmt und mit der Theorie verglichen. Es zeigt sich, dass Theorie und Praxis gut übereinstimmen und es sich bei dem entwickelten Versuchsaufbau um eine gute Methode handelt Strömungswiderstände von Mikrosieben zu bestimmen.

Para o tratamento de esgoto sanitário foi desenvolvido e estudado um reator UASB (Upflow Anaerobic Sludge Blanket), associado com unidade de filtração. O estudo se iniciou pela operação do reator UASB durante 642 dias, onde a fase líquida afluente e efluente foi monitorada. Em seguida uma unidade de filtração foi acoplada ao reator UASB e foram avaliados as características de filtração, o desempenho do tratamento e a eficiência do processo de limpeza química de três filtros. Os materiais poliméricos utilizados como filtros foram o polipropileno, o poliéster e o geossintético de poliéster, com diâmetro médio de poros de um mícron (1&#956;m). As características de filtração avaliadas foram o fluxo do permeado e os mecanismos de obstrução de cada material polimérico (resistência à filtração: total, do material, da camada de biossólidos e de entupimento). O desempenho global do sistema de tratamento foi avaliado em termos de remoção de demanda química de oxigênio (DQO) e de sólidos suspensos totais (SST). Para recuperação dos filtros foi utilizada primeiramente a limpeza química com solução ácida (ácido clorídrico-HCl) e em série a limpeza com solução alcalina (hipoclorito de sódio e hidróxido de sódio- NaOCl e NaOH). Dentre os três materiais poliméricos utilizados verificou-se que, o geossintético (poliéster) foi o filtro que apresentou melhores características de filtração e desempenho global, ou seja, com este material a resistência da camada foi predominante (obstrução é reversível), a concentração de sólidos suspensos totais do permeado estabilizou em 25 mg/L e a eficiência média global de remoção da demanda química de oxigênio (DQO) foi de 78%. Dentre os procedimentos de limpeza química utilizada nos três filtros, verificou-se que a solução ácida (HCl) aplicada em série com a solução alcalina (NaOCl e NaOH) apresentou maior eficiência que a limpeza somente com a solução ácida (recuperação do fluxo inicial do permeado acima de 90%). / An anaerobic reactor (UASB – Upflow Anaerobic Sludge Blanket) coupled to a filtration unit for the treatment of domestic sewage was developed and studied. The study began by operating the UASB reactor for 642 days, during which time the influent and effluent liquid phase were monitored. The filtration unit was then coupled to the UASB reactor and the filtration characteristics, the performance of the treatment, and the efficiency of the cleaning process of three polymeric filters were evaluated. The polymeric materials used for the filters were polypropylene, polyester and geosynthetic polyester, all with an average pore size of one micron (1&#956;m). The filtration characteristics evaluated were the permeate flux and the fouling mechanisms (total filtration resistance of the material and the cake, and clogging) during filtration. The system’s overall performance was evaluated in terms of chemical oxygen demand (COD) and removal of total suspended solids (TSS). The filters were cleaned chemically, first with an acid solution (HCl), followed by alkaline solutions (NaOH and NaOCl) applied in series. A comparison of the three filtering materials indicated that the geosynthetic material (polyester) possessed the best overall characteristics of filtration and performance. In other words, i.e., cake resistance (reversible fouling) predominated with this material, the concentration of total suspended solids (TSS) in the permeate stabilized at 25 mg/L, and the overall removal efficiency of chemical oxygen demand (COD) was 78%. Of the various chemical cleaning procedures tested on the three polymeric filters, the acid (HCl) and alkaline solutions (NaOH and NaOCl) applied in series provided more efficient flux recovery (over 90% of the initial permeate) than chemical cleaning only with acid (HCl).

<p>Ved består huvudsakligen av tre typer av polymerer, cellulosa, hemicellulosa och lignin. Lignin bildas i naturen genom enzymatiskt initierad oxidativ koppling av tre olika typer av fenylpropan-enheter. Dessa bygger genom olika kol-kol- och kol-syre-bindningar upp en amorf tredimensionell polymer. När kemisk massa tillverkas bryts lignin ner och löses ut i kokluten. Luten innehåller de förbrukade kokkemikalierna och bränns generellt i en sodapanna för att regenerera kemikalierna och producera ånga. Sodapannan är emellertid dyr. Därför har den blivit produktionsbegränsande på många massabruk. Att avlägsna en del av ligninet från avluten vore därför önskvärt och att finna ekonomiskt intressanta produkter baserade på lignin från svartlut är därför ett viktigt forskningsområde .</p><p>Ett lämpligt område för ligninprodukter vore som tillsatts i oblekt massa. Oblekt massa används till stor del för tillverkning av kraftliner, topp- och bottenskikten på wellpapp. När lådor av wellpapp lagras i containrar som färdas över haven, förändras den relativa luftfuktigheten. Detta gör att lådorna kollapsar lättare än om de skulle ha lagrats vid konstant luftfuktighet, även en hög sådan. Detta är på grund av det så kallade mekanosorptiva- eller accelererade krypfenomenet. Genom tillsatts av våtstyrkemedel till kraftliner eller behandla den med hydrofoba ämnen, finns indikatoner på att mekanosorptiva effekten skulle kunna minska.</p><p>För att försöka minska den effekten har ett lågmolekylärt kraftlignin, som utvunnits med hjälp av tvärsflödesfiltrering av svartlut och svavelsyrafällning, använts. Genom derivatisering av detta lignin med linolja erhölls ett hydrofobt ligninderivat som uppvisar strukturella likheter med biopolymeren suberin. När detta suberinlika ligninderivat tillsätts till massa verkar det mekanosorptiva krypet minska. När lågmolekylärt lignin används tillsammans med ligninradikalinitiatorerna lackas eller mangan(III) i kraftlinermassa erhålls dessutom en våtstyrka på ca 5% av torrstyrkan. Efter aminering av detta lignin gav en tillsatts till kraftlinermassan en våtstyrka på upp till 10% av torrstyrkan. Det finns indikationer på att det mekanosorptiva krypet samtidigt minskar när dessa behandlingar görs som ger upphov till ökad våtstyrka.</p> / <p>Wood consists mainly of three types of polymers; cellulose, hemi cellulose and lignin. Lignin is formed in nature through enzymatic initiated oxidative coupling of three different kinds of phenyl propane units. These form by various carbon-carbon and carbon-oxygen bonds, an amorphous three-dimensional polymer. As chemical pulp is produced, lignin is degraded and dissolved into pulping liquors. These liquors contain the spent cooking chemicals and are generally burnt in a recovery boiler to regenerate cooking chemicals and produce steam. However, the recovery boiler is expensive. Hence, it has become the bottleneck for production in many pulp mills. Removal of some lignin from the spent cooking liquor would, for that reason, be desired and valuable products based on lignin from cooking liquors are searched for.</p><p>One suitable area for lignin products would be as additive in unbleached pulp. A major product from unbleached pulp is kraftliner, the top and bottom layers of corrugated board. When boxes of corrugated board are stored in containers travelling overseas the relative humidity is varying. This makes the boxes collapse more easily than if they were stored at constant humidity, even a high one. This is due to the so called mechano-sorptive or accelerated creep phenomenon. By addition of wet strength additive to kraftliner or treating it with hydrophobic compounds there are indications on that the mechano-sorptive effect would decrease.</p><p>Trying to decrease this effect, low molecular weight kraft lignin has been used. It was obtained by cross-flow filtration of black liquor and precipitation by sulphuric acid. By derivatisation of this lignin by linseed oil, a hydrophobic lignin derivative was obtained, similar in structure to units in the biopolymer suberin. As this suberin-like lignin-derivative was added to pulp the mechano-sorptive creep seemed to be lowered. Furthermore, when the low molecular weight lignin was used together with the lignin radical initiators laccase or manganese(III) in kraftliner pulp, a wet strength of about 5% of dry strength was obtained. An amination treatment of this lignin and addition to kraftliner pulp resulted in a wet strength of up to 10% of dry strength. There are indications of that the mechano-sorptive creep also decreases as these treatments, resulting in increased wet strength, are made.</p>

Para o tratamento de esgoto sanitário foi desenvolvido e estudado um reator UASB (Upflow Anaerobic Sludge Blanket), associado com unidade de filtração. O estudo se iniciou pela operação do reator UASB durante 642 dias, onde a fase líquida afluente e efluente foi monitorada. Em seguida uma unidade de filtração foi acoplada ao reator UASB e foram avaliados as características de filtração, o desempenho do tratamento e a eficiência do processo de limpeza química de três filtros. Os materiais poliméricos utilizados como filtros foram o polipropileno, o poliéster e o geossintético de poliéster, com diâmetro médio de poros de um mícron (1&#956;m). As características de filtração avaliadas foram o fluxo do permeado e os mecanismos de obstrução de cada material polimérico (resistência à filtração: total, do material, da camada de biossólidos e de entupimento). O desempenho global do sistema de tratamento foi avaliado em termos de remoção de demanda química de oxigênio (DQO) e de sólidos suspensos totais (SST). Para recuperação dos filtros foi utilizada primeiramente a limpeza química com solução ácida (ácido clorídrico-HCl) e em série a limpeza com solução alcalina (hipoclorito de sódio e hidróxido de sódio- NaOCl e NaOH). Dentre os três materiais poliméricos utilizados verificou-se que, o geossintético (poliéster) foi o filtro que apresentou melhores características de filtração e desempenho global, ou seja, com este material a resistência da camada foi predominante (obstrução é reversível), a concentração de sólidos suspensos totais do permeado estabilizou em 25 mg/L e a eficiência média global de remoção da demanda química de oxigênio (DQO) foi de 78%. Dentre os procedimentos de limpeza química utilizada nos três filtros, verificou-se que a solução ácida (HCl) aplicada em série com a solução alcalina (NaOCl e NaOH) apresentou maior eficiência que a limpeza somente com a solução ácida (recuperação do fluxo inicial do permeado acima de 90%). / An anaerobic reactor (UASB – Upflow Anaerobic Sludge Blanket) coupled to a filtration unit for the treatment of domestic sewage was developed and studied. The study began by operating the UASB reactor for 642 days, during which time the influent and effluent liquid phase were monitored. The filtration unit was then coupled to the UASB reactor and the filtration characteristics, the performance of the treatment, and the efficiency of the cleaning process of three polymeric filters were evaluated. The polymeric materials used for the filters were polypropylene, polyester and geosynthetic polyester, all with an average pore size of one micron (1&#956;m). The filtration characteristics evaluated were the permeate flux and the fouling mechanisms (total filtration resistance of the material and the cake, and clogging) during filtration. The system’s overall performance was evaluated in terms of chemical oxygen demand (COD) and removal of total suspended solids (TSS). The filters were cleaned chemically, first with an acid solution (HCl), followed by alkaline solutions (NaOH and NaOCl) applied in series. A comparison of the three filtering materials indicated that the geosynthetic material (polyester) possessed the best overall characteristics of filtration and performance. In other words, i.e., cake resistance (reversible fouling) predominated with this material, the concentration of total suspended solids (TSS) in the permeate stabilized at 25 mg/L, and the overall removal efficiency of chemical oxygen demand (COD) was 78%. Of the various chemical cleaning procedures tested on the three polymeric filters, the acid (HCl) and alkaline solutions (NaOH and NaOCl) applied in series provided more efficient flux recovery (over 90% of the initial permeate) than chemical cleaning only with acid (HCl).

Ved består huvudsakligen av tre typer av polymerer, cellulosa, hemicellulosa och lignin. Lignin bildas i naturen genom enzymatiskt initierad oxidativ koppling av tre olika typer av fenylpropan-enheter. Dessa bygger genom olika kol-kol- och kol-syre-bindningar upp en amorf tredimensionell polymer. När kemisk massa tillverkas bryts lignin ner och löses ut i kokluten. Luten innehåller de förbrukade kokkemikalierna och bränns generellt i en sodapanna för att regenerera kemikalierna och producera ånga. Sodapannan är emellertid dyr. Därför har den blivit produktionsbegränsande på många massabruk. Att avlägsna en del av ligninet från avluten vore därför önskvärt och att finna ekonomiskt intressanta produkter baserade på lignin från svartlut är därför ett viktigt forskningsområde . Ett lämpligt område för ligninprodukter vore som tillsatts i oblekt massa. Oblekt massa används till stor del för tillverkning av kraftliner, topp- och bottenskikten på wellpapp. När lådor av wellpapp lagras i containrar som färdas över haven, förändras den relativa luftfuktigheten. Detta gör att lådorna kollapsar lättare än om de skulle ha lagrats vid konstant luftfuktighet, även en hög sådan. Detta är på grund av det så kallade mekanosorptiva- eller accelererade krypfenomenet. Genom tillsatts av våtstyrkemedel till kraftliner eller behandla den med hydrofoba ämnen, finns indikatoner på att mekanosorptiva effekten skulle kunna minska. För att försöka minska den effekten har ett lågmolekylärt kraftlignin, som utvunnits med hjälp av tvärsflödesfiltrering av svartlut och svavelsyrafällning, använts. Genom derivatisering av detta lignin med linolja erhölls ett hydrofobt ligninderivat som uppvisar strukturella likheter med biopolymeren suberin. När detta suberinlika ligninderivat tillsätts till massa verkar det mekanosorptiva krypet minska. När lågmolekylärt lignin används tillsammans med ligninradikalinitiatorerna lackas eller mangan(III) i kraftlinermassa erhålls dessutom en våtstyrka på ca 5% av torrstyrkan. Efter aminering av detta lignin gav en tillsatts till kraftlinermassan en våtstyrka på upp till 10% av torrstyrkan. Det finns indikationer på att det mekanosorptiva krypet samtidigt minskar när dessa behandlingar görs som ger upphov till ökad våtstyrka. / Wood consists mainly of three types of polymers; cellulose, hemi cellulose and lignin. Lignin is formed in nature through enzymatic initiated oxidative coupling of three different kinds of phenyl propane units. These form by various carbon-carbon and carbon-oxygen bonds, an amorphous three-dimensional polymer. As chemical pulp is produced, lignin is degraded and dissolved into pulping liquors. These liquors contain the spent cooking chemicals and are generally burnt in a recovery boiler to regenerate cooking chemicals and produce steam. However, the recovery boiler is expensive. Hence, it has become the bottleneck for production in many pulp mills. Removal of some lignin from the spent cooking liquor would, for that reason, be desired and valuable products based on lignin from cooking liquors are searched for. One suitable area for lignin products would be as additive in unbleached pulp. A major product from unbleached pulp is kraftliner, the top and bottom layers of corrugated board. When boxes of corrugated board are stored in containers travelling overseas the relative humidity is varying. This makes the boxes collapse more easily than if they were stored at constant humidity, even a high one. This is due to the so called mechano-sorptive or accelerated creep phenomenon. By addition of wet strength additive to kraftliner or treating it with hydrophobic compounds there are indications on that the mechano-sorptive effect would decrease. Trying to decrease this effect, low molecular weight kraft lignin has been used. It was obtained by cross-flow filtration of black liquor and precipitation by sulphuric acid. By derivatisation of this lignin by linseed oil, a hydrophobic lignin derivative was obtained, similar in structure to units in the biopolymer suberin. As this suberin-like lignin-derivative was added to pulp the mechano-sorptive creep seemed to be lowered. Furthermore, when the low molecular weight lignin was used together with the lignin radical initiators laccase or manganese(III) in kraftliner pulp, a wet strength of about 5% of dry strength was obtained. An amination treatment of this lignin and addition to kraftliner pulp resulted in a wet strength of up to 10% of dry strength. There are indications of that the mechano-sorptive creep also decreases as these treatments, resulting in increased wet strength, are made. / QC 20101103

A non-reactive model system comprising a highly concentrated and unstable oil-in-water emulsion was used to investigate the retention of oil by the membrane in producing biodiesel with a membrane reactor. Critical flux was identified using the relationship between the permeate flux and transmembrane pressure along with the separation efficiency of the membrane. It was shown that separation efficiencies above 99.5% could be obtained at all operating conditions up to the critical flux. It was observed that the concentration of oil in all collected permeate samples using the oil-water system was below 0.2 wt% when operating at a flux below the critical flux. Studies to date have been limited to the characterization of low concentrated emulsions below 15 vol.%. The average oil droplet size in highly concentrated emulsions was measured as 3200 nm employing direct light scattering (DLS) measurement methods. It was observed that the estimated cake layer thickness of 20 to 80 mm was larger than external diameter of the membrane tube i.e. 6 mm based on a large particle size. Settling of the concentrated emulsion permitted the detection of a smaller particle size distribution (30-100 nm) within the larger particles averaging 3200 nm. It was identified that DLS methods could not efficiently give the droplet size distribution of the oil in the emulsion since large particles interfered with the detection of smaller particles. The content of the smaller particles represented 1% of the total weight of oil at 30°C and 5% at 70°C. This was too low to be detected using DLS measurements but was sufficient to affect ultrafiltration. In order to study the critical flux in the presence of transesterification reaction and the effect of cross flow velocity on separation, various oils were transesterified in another membrane reactor providing higher cross flow velocity. higher cross flow velocity provides better separation by reducing materials deposition on the surface of the membrane due to higher shearing. The oils tested were canola, corn, sunflower and unrefined soy oils (Free Fatty Acids (FFA< 1%)), and waste cooking oil (FFA= 9%). The quality of all biodiesel samples was studied in terms of glycerine, mono-glyceride, di-glyceride and tri-glyceride concentrations. The composition of all biodiesel samples were in the range required by ASTM D6751 and EN 14214 standards. A critical flux based on operating pressure in the reactor was reached for waste cooking and pre-treated corn oils. It was identified that the reaction residence time in the reactor was an extremely important design parameter affecting the operating pressure in the reactor. / Natural Sciences and Engineering Research Council of Canada (NSERC)

A non-reactive model system comprising a highly concentrated and unstable oil-in-water emulsion was used to investigate the retention of oil by the membrane in producing biodiesel with a membrane reactor. Critical flux was identified using the relationship between the permeate flux and transmembrane pressure along with the separation efficiency of the membrane. It was shown that separation efficiencies above 99.5% could be obtained at all operating conditions up to the critical flux. It was observed that the concentration of oil in all collected permeate samples using the oil-water system was below 0.2 wt% when operating at a flux below the critical flux. Studies to date have been limited to the characterization of low concentrated emulsions below 15 vol.%. The average oil droplet size in highly concentrated emulsions was measured as 3200 nm employing direct light scattering (DLS) measurement methods. It was observed that the estimated cake layer thickness of 20 to 80 mm was larger than external diameter of the membrane tube i.e. 6 mm based on a large particle size. Settling of the concentrated emulsion permitted the detection of a smaller particle size distribution (30-100 nm) within the larger particles averaging 3200 nm. It was identified that DLS methods could not efficiently give the droplet size distribution of the oil in the emulsion since large particles interfered with the detection of smaller particles. The content of the smaller particles represented 1% of the total weight of oil at 30°C and 5% at 70°C. This was too low to be detected using DLS measurements but was sufficient to affect ultrafiltration. In order to study the critical flux in the presence of transesterification reaction and the effect of cross flow velocity on separation, various oils were transesterified in another membrane reactor providing higher cross flow velocity. higher cross flow velocity provides better separation by reducing materials deposition on the surface of the membrane due to higher shearing. The oils tested were canola, corn, sunflower and unrefined soy oils (Free Fatty Acids (FFA< 1%)), and waste cooking oil (FFA= 9%). The quality of all biodiesel samples was studied in terms of glycerine, mono-glyceride, di-glyceride and tri-glyceride concentrations. The composition of all biodiesel samples were in the range required by ASTM D6751 and EN 14214 standards. A critical flux based on operating pressure in the reactor was reached for waste cooking and pre-treated corn oils. It was identified that the reaction residence time in the reactor was an extremely important design parameter affecting the operating pressure in the reactor. / Natural Sciences and Engineering Research Council of Canada (NSERC)