Segui questo link per vedere altri tipi di pubblicazioni sul tema: Pretreatment.
Tesi sul tema "Pretreatment"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Vedi i top-50 saggi (tesi di laurea o di dottorato) per l'attività di ricerca sul tema "Pretreatment".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Vedi le tesi di molte aree scientifiche e compila una bibliografia corretta.
1
Xu, Bingjie. "Improved Membrane Pretreatment by Floatation". Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32614.
Testo completoAbstract (sommario):
Coagulation/flocculation/sedimentation is a common pretreatment process prior to microfiltration (MF) or ultrafiltration (UF) to alleviate membrane fouling, however there has been limited research on floatation as the pretreatment separation process. The main objective of this study is to compare sedimentation with floatation as part of the pretreatment for ultrafiltration of Ottawa River water (ORW) with relatively high natural organic matter (NOM) content. Water samples pretreated at two full-scale plants were subjected to multiple-day UF membrane fouling tests (constant flux with backwash and chemical cleaning) using an automated bench-scale UF hollow fiber membrane system.
For all the experiments, the transmembrane pressure (TMP) increased sharply during the beginning of the operation (~10 h), which indicated the adsorption was significant. In the later cycles, the TMP showed a more linear constant increase, which indicated the built up of the cake layers.
The total fouling index (TFI), hydraulically irreversible fouling index (HIFI) and chemical irreversible fouling index (CIFI) for floated water were much smaller than those of settled waters during both summer and winter testing. Thus, for this type of water coagulation/floatation pretreatment was superior process compared to coagulation/sedimentation, the decreased fouling appears to be linked to greater hydrophobic NOM removal by the coagulation/floatation. For all the tests, HIFI/TFIs were less than 0.1, which is to mean most of the fouling was reversible by hydraulic backwashing.Large fluctuation of backwash efficiencies with time were found for all the tested waters.
Enhanced chemical backwash with 100 ppm chlorine and chemical clean with 0.1N NaOH & 200 ppm chlorine were found to be very effective at reducing fouling for pretreated ORW. As expected longer filtration cycles resulted in greater fouling but with a slightly greater degree of hydraulically reversible fouling.
2
Wang, Liqian. "Different Pretreatments to Enhance Biogas Production : A comparison of thermal, chemical and ultrasonic methods". Thesis, Högskolan i Halmstad, Ekologi och miljövetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-16190.
Testo completo
3
Ikiz, Nida. "Field investigation of anti-icing/pretreatment". Ohio : Ohio University, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1176405449.
Testo completo
4
Nkansah-Boadu, Frank. "Delectric heating pretreatment of organic slurries". Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/45627.
Testo completo
5
Badir, Amir. "Thermal pretreatment of municipal solid waste". Thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-17615.
Testo completoAbstract (sommario):
A kinetic study of the pyrolysis of municipal solid waste (MSW) was carried out bythermogravimetric analysis (TGA). Different runs were performed at heating rates of 5, 10and 150C/min. The effect of the N2, CO2 and O2 gas with different combination in theprocess was also evaluated. The results show that the most weight loss was obtained whenthe MSW was treated at a temperature interval of (20-750)0C which led to a weigh loss of95%. The kinetic study of the pyrolysis process showed also the gas mixture used in theprocess effect also the activation energy of the process and the presence of the CO2 in theincreased the activation energy (Ea) to 56 kJ/mol. Higher concentration of CO2 in the processlead to increase in the activation energy which is not optimal for the reaction. The treated andthe untreated samples were incubated and the biological activity was observed. The resultsshow that the pretreated samples did not have any biological activity. From these results itcould be concluded that the thermal pretreatment could be an alternative way for of waste forlong period of time, which could have significant impact in i.e. for transportation anddurability during storage.Program: Högskoleingenjörsutbildning i kemiteknik
6
Brandt, Agnieszka. "Ionic liquid pretreatment of lignocellulosic biomass". Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9166.
Testo completoAbstract (sommario):
This thesis is concerned with the thermal treatment of lignocellulosic biomass using ionic liquids for the purpose of comminution via dissolution, for fractionating the biological composite and for obtaining aqueous solutions of carbohydrate monomers from the pulp via enzymatic hydrolysis. A major focus was the relationship between the choice of the anion and the effectiveness of the treatment. The synthesis of a range of 1-butyl-3-methylimidazolium ionic liquids with strongly hydrogen-bond basic anions was accomplished. Selected, process-relevant physicochemical properties were measured, such as the Kamlet-Taft solvent polarity, hygroscopicity and thermal stability. It was shown that 1-butyl-3-methylimidazolium acetate is not stable at 120°C, while other ionic liquids e.g. 1-butyl-3-methylimidazolium hydrogen sulfate exhibit very good long-term thermal stability. It was shown that hydrogen-bond basic 1-butyl-3-methylimidazolium ionic liquids attract more than stoichiometric quantities of water when exposed to air, suggesting that ionic liquid pretreatment under anhydrous conditions is difficult to achieve. Dissolution of air-dried wood chips in 1-butyl-3-methylimidazolium ionic liquids was attempted. It was shown that the large particle size and the moisture contained in the biomass hamper complete dissolution. The hydrogen-bond basicity of the ionic liquid, described by the Kamlet-Taft parameter ß, was correlated with the ability to expand as well as partially and anisotropically dissolve wood chips. Pretreatment of lignocellulosic biomass with 1-butyl-3- methylimidazolium methyl sulfate, 1-butyl-3-methylimidazolium hydrogen sulfate and 1-butyl-3-methylimidazolium methanesulfonate was explored and high saccharification yields were reported. It was found that successful application of methyl sulfate and hydrogen sulfate ionic liquids requires addition of water and that comparatively high water contents are tolerated. Fractionation of lignocellulose into an insoluble cellulose fraction, a solubilised hemicellulose fraction and a lignin containing precipitate was achieved. The influence of water content, pretreatment time and biomass type on the enzymatic saccharification yield and the extent of hemicellulose solubilisation, hydrolysis and dehydration were examined.
7
Patterson, Candace L. "Pretreatment Role Expectations, Alliance, and Outcome". Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1276547700.
Testo completo
8
Sierra, Ramirez Rocio. "Long-term lime pretreatment of poplar wood". Texas A&M University, 2005. http://hdl.handle.net/1969.1/3316.
Testo completoAbstract (sommario):
Lignocellulosic biomass (e.g., poplar wood) provides a unique and sustainable resource
for environmentally safe organic fuels and chemicals. The core of this study is the
pretreatment step involved in bioconversion processes. Pretreatment is required to realize
high yields vital to commercial success. The focus of the pretreatment step is to
methodically change key features of the biomass to favor enzymatic hydrolysis.
This work assesses the compositional changes due to oxidative and non-oxidative longterm
lime pretreatment of poplar wood (up to 4 weeks of pretreatment) at mild
temperatures (25ºC to 65ºC), and their effect on the enzymatic yield of glucan and xylan.
The most important pretreatment yield of lignin was 54 g lignin remaining/100 g lignin
in raw biomass, and was accomplished for 4-week lime pretreatment at 65ºC in oxidative
conditions. The corresponding pretreatment yields of glucan and xylan were 85.9 g glucan
recovered/100 g glucan in raw biomass and 80.2 g xylan recovered/100 g xylan in raw
biomass respectively.
For poplar wood oxidatively pretreated with lime for 4 weeks at 65ºC and
enzymatically hydrolyzed with an enzyme loading of 15 FPU/g glucan in raw biomass
during a 3-day period, the best overall yields of glucan and xylan, were 80.7 g glucan
hydrolyzed/100 g glucan in raw biomass and 66.9 g xylan hydrolyzed/100 g xylan in raw
biomass respectively. The corresponding hydrolysis yields were 94.0 g glucan
hydrolyzed/100 g glucan in treated biomass and 83.5 g xylan hydrolyzed/100 g xylan in
treated biomass respectively.
Because there is a previous study of long-term lime pretreatment of corn stover (Kim,
2004), the data obtained in this work show the effect of using woody lignocellulose as
substrate. From the comparison, resulted that in the case of poplar wood oxidatively pretreated at
65ºC for 4 weeks, less lignin was removed and more carbohydrates were solubilized,
however the hydrolysis yield of glucan was almost equal and the hydrolysis yield of xylan
was higher than the reported by Kim for corn stover oxidatively pretreated at 55ºC for 4
weeks. The overall yield of glucan resulted lower in the case of poplar wood because of the
lower pretreatment yield of glucan. Thus, it is important to complete the mass balances
including an analysis on the pretreatment liquor to determine if the solubilized glucan was
degraded.
9
Corredor, Deisy Y. "Pretreatment and enzymatic hydrolysis of lignocellulosic biomass". Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/693.
Testo completo
10
Mohr, David Larry. "Pretreatment and pyrolysis of polyorganosilazane preceramic binders". Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/8626.
Testo completo
11
Dragoo, Ron. "Pretreatment Optimization of Fiberglass Manufacturing Industrial Wastewater". Thesis, University of North Texas, 1998. https://digital.library.unt.edu/ark:/67531/metadc277875/.
Testo completoAbstract (sommario):
Wastewater effluent produced in the fiberglass manufacturing industry contains a significant amount of total suspended solids. Environmental regulations require pretreatment of effluent before it is discharged to the municipal wastewater treatment plant. Chemical precipitation by coagulation and flocculation is the method of pretreatment used at the Vetrotex CertainTeed Corporation (VCT). A treatability study was conducted to determine conditions at which the VCT Wastewater Pretreatment Plant could operate to consistently achieve a total suspended solids concentration ≤ 200-mg/L. Jar tests varied pH, polymer dosage, and ferric sulfate dosage. Total suspended solids and turbidity were measured to evaluate treatment performance. The data were used to determine an optimum set of conditions under project guidelines. Of twelve polymers screened, BPL 594 was selected as the most effective polymer. For cost efficiency in the wastewater pretreatment operation, recommendations suggested that treatment chemical injection be electronically controlled according to turbidity of the treated effluent.
12
Cheng, Wei. "Pretreatment and enzymatic hydrolysis of lignocellulosic materials". Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=1951.
Testo completoAbstract (sommario):
Thesis (M.S.)--West Virginia University, 2001.Title from document title page. Document formatted into pages; contains xii, 173 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 138-142).
13
Stenman, Johan. "Pretreatment Methods for Manganese Containing Anode Sludge". Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65751.
Testo completoAbstract (sommario):
This master thesis work examines whether it is possible to separate lead from an electrolytic sludge rich in manganese using pyrometallurgical treatment, and also attempts to determine the optimum process parameters for such a treatment. It also includes a theoretical study of the possible applications for lead and manganese, as well as thermodynamic calculations predicting the behaviour of the material at increasing temperatures. The experimental work completed includes characterisation and agglomeration of the raw material, as well as tests in a chamber furnace and a rotary furnace. The anode sludge was characterised using chemical analysis, XRD, SEM and PSD. The anode sludge was agglomerated into pellets using either both bentonite and water, or only water as binder. The smaller scale tests in the chamber furnace examined the impact of several variables on lead removal. These variables included type and amount of reduction agent used, temperature, and whether the anode sludge was added as untreated material or pellets. The most promising of these results were further tested in the rotary furnace at a slightly larger scale. The variables used for the rotary furnace tests were amount of reduction agent added, whether the anode sludge was added as untreated material or pellets, and whether the reduction agent was added at the start of or during the experiment. All samples were sent for chemical analysis, and selected samples were further analysed using XRD and SEM. The conclusions drawn from the results of the thermodynamic calculations and experimental work are as follows: In the untreated anode sludge the primary phases are MnO2, CaSO4, and (Pb,Sr)SO4. The anode sludge can be agglomerated into pellets, with or without added binder. After treatment the primary phases present are MnO and (Ca,Sr)2SiO4. Lead is present as small separate grains. The most effective treatment method should adhere to the following parameters:Use of a rotating furnace. Anode sludge added in the form of pellets, to simplify materials handling. Temperature of 1400-1500 °C. Reduction agent added in batches after initial smoke formation has stopped. Total addition of reduction agent should be 10 wt% of anode sludge. Significant weight loss occurs during treatment. The amount of reduction agent added to the anode sludge has the greatest effect on the removal of lead and zinc. Charcoal is a potential candidate for a renewable reduction agent, but leads to increased weight loss. It is possible to separate lead from the manganese anode sludge using pyrometallurgical treatment, down to 100 ppm. Zinc can also be separated, down to 600 ppm.Detta examensarbete undersöker huruvida det är möjligt att separera bly från ett anodslam rikt i mangan med hjälp av pyrometallurgiska behandlingsmetoder, och försöker även avgöra de optimala processparametrarna för en sådan behandling. Arbetet inkluderar även en teoristudie av möjliga användningsområden för bly och mangan, samt termodynamiska beräkningar som förutser materialets beteende vid ökande temperaturer. Det experimentella arbetet som utförts inkluderar karakterisering och agglomerering av råmaterialet, samt försök i en kammarugn och en rullugn. Anodslammet karakteriserades med hjälp av kemisk analys, XRD, SEM, och partikelstorleksfördelning. Anodslammet agglomererades till pellets med antingen bentonit och vatten eller bara vatten som bindemedel. Försöken i mindre skala i kammarugnen undersökte hur flera variabler påverkade blyavdrivningen. Dessa variabler inkluderade typ och mängd av reduktionsmedel som tillsattes, temperatur, och huruvida anodslammet som användes var obehandlat material eller pellets. De mest lovande av dessa resultat användes för vidare försök i rullugnen i något större skala. Variablerna som undersöktes vid rullugnsförsöken var mängd reduktionsmedel som tillsattes, huruvida anodslammet som användes var obehandlat material eller pellets, samt huruvida reduktionsmedlet tillsattes vid start eller under försökets gång. Alla prover skickades för kemisk analys, och utvalda prover analyserades ytterligare med XRD och SEM. Slutsatserna som dragits utifrån resultaten av de termodynamiska beräkningarna och det experimentella arbetet är som följande: I det obehandlade anodslammet är de primära faserna MnO2, CaSO4, och (Pb,Sr)SO4. Anodslammet kan agglomereras till pellets. Efter behandling är de primära faserna i materialet MnO och (Ca,Sr)2SiO4. Kvarvarande bly är närvarande som små separata korn. Den mest effektiva behandlingsmetoden bör använda följande parametrar: Användning av en roterande ugn. Anodslam bör tillsättas i form av pellets för att underlätta materialhantering. Temperatur mellan 1400-1500 °C. Reduktionsmedel tillsatt i omgångar efter att initial rökbildningen avstannat. Total tillsats av reduktionsmedel bör vara 10 vikt% av anodslammets vikt. Signifikanta viktförluster under behandling. Mängden tillsatt reduktionsmedel är den faktor som har störst effekt på avlägsnandet av bly och zink. Träkol är en potentiell kandidat för ett förnyelsebart reduktionsmedel, men orsakar ökade viktförluster. Det är möjligt att separera bly från mangan med hjälp av pyrometallurgiska metoder, ned till 100 ppm bly. Zink kan också separeras, ned till 600 ppm.
14
Thorsness, Adam G. "Surface Pretreatment for Thin Film Surface Reactivity". Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/194965.
Testo completoAbstract (sommario):
The formation of a self-limiting interface layer for the integration of high-k dielectric materials into silicon based transistor devices was investigated. Chlorine atoms were used to activate a liquid cleaned Si(100) surface for the reaction with H₂O(g). A saturation coverage of 0.8 monolayers of chlorine atoms was deposited on a hydrogen terminated Si(100) surface by exposure to Cl₂ gas at 10 Torr under ultraviolet illumination at 300 K. The self-limiting interface layer was formed by exposing the chlorine terminated surface to water vapor at P(HOH)=100 Torr and temperatures ranging from 325 to 373 K. The coverage of oxygen resulting from H₂O exposures was directly correlated with a decrease in the Cl coverage and ranged from 0.2-1.2 monolayers. Complete removal of surface chlorine was achieved by 100°C water exposures in 45 minutes. The final chapter summarizes three papers published which describe the moisture absorption into borophosphosilicate glass (BPSG) films and an investigation of a gas phase etching process applied to borosilicate glass (BSG), phosphosilicate glass (PSG), and BPSG films. The absorption and reaction of water with doped and undoped oxides as well as the effect of annealing was investigated using a variety of annealed BPSG films. Asdeposited (AD) and annealed (500, 750, and 900°C) borophosphosilicate glass (BPSG) films were characterized during aging, baking, and etching using transmission Fourier transform infrared spectroscopy and ellipsometry. The water content in the BPSG films increased steadily during storage at ambient conditions. The B-O bond was shown to be the primary site for water adsorption on the surface of the film. Water absorption into the film was consistent with a reaction-limited model. It is likely that the water present reacted readily with P=O groups forming P-O and PO-H. This slower reaction with P=O species is proposed as the rate-limiting step for water absorption. The etching of BPSG with gas phase HF produced a low volatility residue consisting of a mixture of boric acid B(OH)₃, phosphoric acid H₃PO₄, and water. Partial removal of the residue was accomplished using both direct and indirect UV–Cl₂ processes.
15
Moharreri, Ehsan. "Optimization, Scale Up and Modeling CO2-Water Pretreatment of Guayule Biomass". University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1313013654.
Testo completo
16
Kang, Yuzhi. "Biomass pretreatment toward efficient hydrolysis for sustainable biofuel applications". Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54852.
Testo completoAbstract (sommario):
The production of biofuels from non-edible plant biomass has been necessitated by the concern for the environmental consequences of fossil fuel use and the tightening of supply and demand for liquid fuels. In contrast to first generation biofuels which rely on crops used for food supplies, second generation biofuels, derived from lignin-containing feedstocks, completely eliminate the competition for food. The major challenges associated with second generation biofuels are both technical and economic. Due to the recalcitrant nature of the raw biomass materials to further biological conversion, their structural degradation often requires severe and costly pretreatment processes such as heat, physical and chemical treatments to disturb and fractionate the biomass. Significant research effort has been devoted to understanding the recalcitrant nature and to accelerate the commercialization process of second generation biofuels. In this thesis, three pretreatment methods that belong to different categories have been investigated to understand their impacts on cellulose and/or lignocellulose and the subsequent hydrolysis steps.
Physicochemical pretreatments, such as steam explosion, have been identified as one of the most effective and cost-efficient pretreatment methods for lignocelluosic materials. In Chapter 2, SO2-catalyzed steam explosion will be discussed and the effect of pretreatment severity on the substrate characteristics and degradation efficiency is also elucidated. Although the crystallinity index (CrI) of cellulose decreases as the severity increases, significant non-specific degradation and low yield of cellulose was observed at high severity. A new method for cellulose CrI determination has been developed with least squares curve fitting and validated with mechanically mixed cellulose samples. Biological pretreatment is another pathway through which the biomass structure can be modified to obtain a more amenable state for enzymatic degradation. Cellulose-binding domain (CBD) originated from Trichoderma reesei Cel7A (i.e. Tr cellobiohydrolase I) has been discovered as a potential biological pretreatment agent which is capable of modifying cellulose crystal structure. An extensive study on the protein engineering, expression, purification and functionalities of Cel7A CBDs was carried out (Chapter 3). The target mutations were identified with a computational protein engineering method involving principal component analysis (PCA). Due to the lack of catalytic activity and high throughput screening method, the library size was limited to nine. The wild-type and mutated CBDs were compared for their adsorption behavior and decrystallization effect on cellulose. Resulting saccharification efficiency after CBD pretreatment were studied and a possible explanation for the rate enhancement was proposed.
In addition to physicochemical and biological pretreatment methods, chemical pretreatment is also a commonly employed method to overcome the recalcitrance of lignocellulosic materials. The most widely studied include dilute acid, alkaline, and organosolv processes. Inspired by the rapidly growing green solvent ionic liquid (IL) researches in biomass pretreatment, substituted imidazoles have been investigated in this thesis to assess their potential as pretreatment agents for lignocelluloses (Chapter 4). 1-Methylimidazole (MI), a precursor to some ILs, has been determined to be the most promising agent for lignocellulose pretreatment due to its exceptional delignification and cellulose expansion efficiency. The chemical recovery and MI process development will also be discussed in Chapter 4.
In order to understand pretreatment effect, a semi-quantitative assay utilizing low molecular weight direct dyes and cellulases to estimate the accessibility and pore size distribution has been developed for application on pure cellulose substrates in Chapter 5. Finally, main conclusions as well as future perspectives for this work will be discussed in Chapter 6.
17
Kim, Se Hoon. "Lime pretreatment and enzymatic hydrolysis of corn stover". Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/2208.
Testo completoAbstract (sommario):
Renewable energy sources, such as lignocellulosic biomass, are environmentally friendly because they emit less pollution without contributing net carbon dioxide to the atmosphere. Among lignocellulosic biomass, corn stover is a very useful feedstock to economically produce environmentally friendly biofuels. Corn stover was pretreated with an excess of calcium hydroxide (0.5 g Ca(OH)2/g raw biomass) in non-oxidative and oxidative conditions at 25, 35, 45, and 55oC. The optimal condition is 55oC for 4 weeks with aeration, determined by yields of glucan and xylan. The overall yields of glucose (g glucan hydrolyzed/100 g original glucan) and xylose (g xylan hydrolyzed/100 g original xylan) were 91.3 and 51.8 at 15 FPU/g cellulose, respectively. Furthermore, when considering the dissolved fragments of glucan and xylan in the pretreatment liquors, the overall yields of glucose and xylose were 93.2 and 79.5 at 15 FPU/g cellulose, respectively. The pretreatment liquor has no inhibitory effect on ethanol fermentation using Saccharomyces cerevisiae D5A. At the recommended condition, only 0.073 g Ca(OH)2 was consumed per g of raw corn stover. Under extensive delignification conditions, 87.5% of the initial lignin was removed. Extensive delignfication required oxidative treatment and additional lime consumption. Deacetylation quickly reached a plateau within 1 week. Delignification highly depended on temperature and the presence of oxygen. Lignin and hemicellulose were selectively removed, but cellulose was not affected by lime pretreatment in mild temperatures (25 ?? 55oC). The delignification kinetic models of corn stover were empirically determined by three simultaneous first-order reactions. The activation energies for the oxidative delignification were estimated as 50.15 and 54.21 kJ/mol in the bulk and residual phases, respectively. Crystallinity slightly increased with delignification because amorphous components (lignin, hemicellulose) were removed. However, the increased crystallinity did not negatively affect the 3-d sugar yield of enzyme hydrolysis. Oxidative lime pretreatment lowered the acetyl and lignin contents to obtain high digestibility, regardless of crystallinity. The enzymatic digestibility of lime-treated biomass was affected by the change of structural features (acetylation, lignification, and crystallization) resulting from the treatment. The non-linear models for 3-d hydrolysis yields of glucan and xylan were empirically established as a function of the residual lignin fraction for the corn stover pretreated with lime and air.
18
Augustino, Bridgett. "Pretreatment Characteristics of Legally Coerced Drug Treatment Seekers". TopSCHOLAR®, 2001. http://digitalcommons.wku.edu/theses/615.
Testo completoAbstract (sommario):
This study examines the sociodemographics, drug use, criminal, and treatment histories of 598 residential and outpatient legally coerced drug treatment seekers in the Kentucky Treatment Outcome and Performance Pilot Studies Enhancement Project. Analyses examined whether users/addicts entering chemical dependency treatment under legal coercion differed from nonlegally coerced treatment seekers. Stanley Cohen's theoretical model of social control provided the theoretical framework for the study. Results showed demographic and behavioral differences were noted between respondents under no coercion and those under legal coercion on gender, age, educational status, pretreatment criminality and current treatment modality. In addition, differences between the legally coerced and not legally coerced clients varied across geographic regions.
19
Yi, Weigang. "Innovative sludge pretreatment technologies and enhanced anaerobic digestion". Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43650.
Testo completoAbstract (sommario):
This dissertation reports the research findings from an investigation into the use of four technologies for municipal wastewater sludge pre-digestion treatment. The technologies explored include microwave, the microwave / hydrogen peroxide process, ultrasound and biological enzyme protease treatment. The general purpose of the sludge pretreatment applications is to improve anaerobic digestion efficiency in terms of biogas production, organic reduction and nutrient recovery.
An examination was first carried out on the effects of these technologies on sludge solubilization (disintegration and hydrolysis), and the various factors influencing treatment efficiencies. Further detailed investigation was undertaken on the sludge macromolecule solubilization, biomass cell destruction and particle size alteration. Finally, an evaluation of the pretreatment impact on both mesophilic and thermophilic anaerobic digestion was done.
This research work found that the degree of sludge solubilization is depending on a number of operating factors such as specific energy, temperature, power input, power density, treatment time, and specific oxidant dosage. In general, specific energy is the dominant factor.
Substantial improvements in organic solubilization by the pretreatments were recorded (up to 43% increase in COD, 50% in protein solubilized, at specific energy 5000 kJ/g-DS). Different treatment methods resulted in variation in solubilization effect and digestion performance. Amino acid was found to be the key parameter in correlating to the mesophilic digestion improvements.
Pretreatment improves biodegradability in mesophilic digestion (25% total biogas production increase). The mesophilic digestion reaction was found to fit second-order kinetics. Thermophilic digestion was inhibited initially by the large increase in soluble substrates, but recovered at the end of digestion period. The biogas production increase in mesophilic digestion was correlated to the increase in amino acids (R²=0.9216), not the increase in overall soluble COD. The inhibition in thermophilic digestion was correlated to the sum of increased soluble protein, polysaccharides and amino acids (R²=0.9822), regardless of the different pretreatment methods used. Overall, ultrasound pretreatment was found to be better energy efficient that other methods tested.
20
Morgan, Caitlin D. "Effects of catalyst pretreatment for carbon nanotube growth". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/44816.
Testo completoAbstract (sommario):
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007.Includes bibliographical references (leaves 36-37).
The effects of pretreatment of iron catalyst for carbon nanotube (CNT) growth was studied. CNTs were grown on Fe/A1203 (1/10 nm) thin-film catalyst deposited on silicon substrates via exposure to C2H4 in a thermal chemical vapor deposition (CVD) furnace. During CVD, the sample was exposed to a carrier gas (Argon) for the 35-minute temperature ramp, and 15-minute anneal, then to a mix of carrier gas and ethylene for a 15-minute growth stage. Experiments were performed varying the amount of oxygen contaminant in the carrier gas, and the time of hydrogen introduction. Samples were characterized via atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that the later hydrogen was introduced, the higher the catalyst density and the taller the CNT carpet. The catalyst efficiency was also shown to increase with later hydrogen introduction. No clear trend was observed between the amount of oxygen in the carrier gas and the height of CNT growth. Data points to the model of catalyst coarsening being crucial to the nucleation and growth of CNTs and the parameters of CNTs grown. Variations in trends are discussed.
by Caitlin D. Morgan.
S.B.
21
Lynam, Joan Goerss. "Biomass Pretreatment using Ionic Liquid and Glycerol Mixtures". Thesis, University of Nevada, Reno, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3724134.
Testo completoAbstract (sommario):
Lignocellulosic biomass is a renewable, sustainable resource that can replace or supplement fossil fuels use for liquid fuels and chemicals. However, its recalcitrant structure including interwoven cellulose, hemicelluloses, and lignin biomacromolecules is challenging to deconstruct. Pretreating biomass so that it can be converted to useful liquids dominates process economics. Many pretreatment methods exist, but most require hazardous chemicals or processing conditions. Many ionic liquids (ILs), salts molten below 100°C, can be used to deconstruct lignocellulosic biomass and are less hazardous than the volatile organic compounds typically used.
While effective, relatively safe, and recyclable, ILs are expensive. To reduce costs, dilution with other safe compounds is desirable, if there is no impact on deconstruction efficiency. Glycerol, a food additive, is inexpensive and becoming even more so since it is a by-product of the burgeoning biodiesel industry. Use of glycerol as an additive or diluent for ILs is extensively evaluated in this work.
Rice hulls are an abundant biomass, with over 100 million tons produced per year, but with little practical use. The IL 1-ethyl-3-methylimidazolium formate ([C2mim][O2CH] or EMIM Form) when mixed with an equal amount of glycerol has been shown to be effective in pretreating rice hulls. Ambient pressure, a pretreatment temperature of 110°C, and a reaction time of three hours produced rice hulls that could be enzymatically hydrolyzed to give reasonably good glucose and xylose yields considering the recalcitrance of this silica-armored biomass.
The IL [C2mim][O2CH] was also effective when mixed with an equal amount of glycerol to pretreat loblolly pine, a fast-growing softwood. Loblolly pine was pretreated at 140°C for three hours to produce a solid rich in cellulose and hemicelluloses, while a lignin-rich product could be precipitated from the IL. Similar products were obtained from pretreatment with a mixture of 75% 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc] or EMIM Ac) and 25% glycerol. Enzymatic hydrolysis of the pretreated solids gave glucose, mannose, and xylose yields up to 18 times that of the raw pine.
Viscosity measurements of pure glycerol, [C2mim][O2CH], [C2mim][OAc], and IL-glycerol mixtures were very different at ambient temperature, but were similar at typical biomass pretreatment temperatures. Biomass pretreated by mixtures with higher viscosity tended to give better carbohydrate yields after enzymatic hydrolysis. Higher excess molar volumes, Vm E, tended to align with better carbohydrate yields after enzymatic hydrolysis. This phenomenon may relate to more energy put into shearing flow of the IL-glycerol-biomass system resulting in biomass particle shearing or stretching that allowed better solvent access into the biomass.
22
Ikiz, Nida Noorani. "Field and Laboratory Investigation of Anti-Icing/Pretreatment". Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1206420618.
Testo completo
23
Narayana, Swamy Naveen. "Supercritical Carbon Dioxide Pretreatment of Various Lignocellulosic Biomasses". Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1269524607.
Testo completo
24
Zhu, Zongyuan. "Microwave assisted pretreatment for C4 plants in biorefinery". Thesis, University of York, 2015. http://etheses.whiterose.ac.uk/11942/.
Testo completoAbstract (sommario):
There is a rising global demand for energy and growing concerns about greenhouse gas emissions. Lignocellulosic biomass offers great potential for second generation bioethanol production, based on the biorefinery philosophy. It is composed of a network of interconnected polymers cellulose, hemicellulose and lignin which has evolved to develop recalcitrance against enzyme hydrolysis produced by microorganisms in nature. Therefore, pretreatment is necessary to make the biomass structure more accessible for enzyme to hydrolysis. The aim of this thesis is to demonstrate the potential of using microwave to assist thermo-chemical pretreatment for lignocellulosic biomass, namely Miscanthus, sugarcane bagasse and maize. The pretreatment process was influenced by pretreatment temperature, pretreatment media and holding time. 0.2 M -1 M H2SO4 and NaOH were used as preteatment media. Firstly, temperature optimisation was carried on Miscanthus and the results showed that 180 oC was the optimal temperature to efficiently release monosaccharides from biomass. In comparison with classic conventional heating pretreatment, microwave assisted pretreatments maximally released 12.5 times more reducing sugars during the pretreatment process. Secondly, the reducing sugar constitutions were tuned by change holding time or pretreatment media, because hemicellulose was easier to be broken down than cellulose. Xylose and glucose were selectively produced by using NaOH and H2SO4 (or FeCl3) respectively as pretreatment media. Chemical compositions and biomass morphological changes were investigated and compared. The significant removal of hemicellulose and lignin, as well as more dismantled fibre structure led to enhanced bioethanol conversion via SSF process (simultaneous saccharification fermentation). Similar study was conducted on sugarcane bagasse and maize. The performance of pretreatment media was similar. However, their optimal conditions for reducing sugar release were different, probably due to different chemical compositions percentages and biomass structure. Overall, in comparison with conventional heating pretreatment, microwave assisted pretreatment is much energy efficient and effective, showing promising potential in the biorefinery process.
25
Loku, Umagiliyage Arosha. "PRETREATMENT OF SWEET SORGHUM BAGASSE TO IMPROVE ENZYMATIC HYDROLYSIS FOR BIOFUEL PRODUCTION". OpenSIUC, 2013. https://opensiuc.lib.siu.edu/theses/1259.
Testo completoAbstract (sommario):
With recent emphasis on development of alternatives to fossil fuels, sincere attempts are being made on finding suitable lignocellulosic feedstocks for biochemical conversion to fuels and chemicals. Sweet Sorghum is among the most widely adaptable cereal grasses, with high drought resistance, and ability to grow on low quality soils with low inputs. It is a C4 crop with high photosynthetic efficiency and biomass yield. Since sweet sorghum has many desirable traits, it has been considered as an attractive feedstock. Large scale sweet sorghum juice extraction results in excessive amounts of waste sweet sorghum bagasse (SSB), which is a promising low cost lignocellusic feed stock. The ability of two pretreatment methods namely conventional oven and microwave oven pretreatment for disrupting lignocellulosic structures of sweet sorghum bagasse with lime [Ca(OH)2] and sodium hydroxide [NaOH] was evaluated. The primary goal of this study was to determine optimal alkali pretreatment conditions to obtain higher biomass conversion (TRS yield) while achieving higher lignin reduction for biofuel production. The prime objective was achieved using central composite design (CCD) and optimization of biomass conversion and lignin removal simultaneously for each alkali separately by response surface method (RSM). Quadratic models were used to define the conditions that separately and simultaneously maximize the response variables. The SSB used in this study was composed of cellulose, hemicellulose, and lignin in the percentage of 36.9 + 1.6, 17.8 + 0.6, and 19.5 + 1.1, respectively. The optimal conditions for lime pretreatment in the conventional oven at 100 °C was 1.7 (% w/v) lime concentration (=0.0024 molL-1), 6.0% (w/v) SSB loading, 2.4 hr pretreatment time with predicted yields of 85.6% total biomass conversion and 35.5% lignin reduction. For NaOH pretreatment, 2% (w/v) alkali (=0.005 molL-1), 6.8% SSB loading and 2.3 hr duration was the optimal level with predicted biomass conversion and lignin reduction of 92.9% and 50.0%, respectively. More intensive pretreatment conditions removed higher amount of hemicelluloses and cellulose. Microwave based pretreatments were carried out in a CEM laboratory microwave oven (MARS 6-Xpress Microwave Reactions System, CEM Corporation, Matthews, NC) and with varying alkali concentration(0.3 - 3.7 % w/v) at varying temperatures (106.4 - 173.6 °C), and length of time (6.6 - 23.4 min). The NaOH pretreatment was optimized at 1.8 (% w/v) NaOH, 143 °C, 14 min time with predicted yields of 85.8% total biomass conversion and 78.7% lignin reduction. For lime pretreatment, 3.1% (w/v) lime, 138 °C and 17.5 min duration was the optimal level with predicted biomass conversion and lignin reduction of 79.9% and 61.1%, respectively. Results from this study were further supported by FTIR spectral interpretation and SEM images.
26
Schneider, L. (Laura). "Mechanocatalytic pretreatment of lignocellulosic barley straw to reducing sugars". Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526216478.
Testo completoAbstract (sommario):
Abstract Biomass conversion methods represent bioeconomic solutions for the sustainable production of value added commodities (chemicals and materials) as well as for energy purposes, either in solid (pellets), liquid (transport fuels) or gaseous (combustion gases e.g. biomethane) form. Lignocellulosic biomass as a renewable source available in immense quantity, is considered to be one of the most promising natural sources, with high potential in the replacement of conventional transportation fuels and reduction of greenhouse gas emissions. This thesis provides new insights into mechanocatalysis, which as yet is a novel technique in catalytic biomass conversion. The mechanocatalytic approach combines chemical catalysis and mechanical assisted processing driven by ball milling. Lignocellulosic barley straw was impregnated or merely mixed with the catalyst (formic acid, acetic acid, sulfuric acid, oxalic acid dihydrate and potassium pyrosulfate) and ball milled under various conditions yielding the selective depolymerization of lignocellulose into water-soluble xylo-oligosaccharides. Subsequent hydrolysis at moderate temperatures resulted in the formation of valuable reducing sugars, mainly xylose, galactose, arabinose and glucose, which constitute the basic materials for transportation fuel and chemical production. Reducing sugar release of 53.4 wt% with low by-product formation was observed within short milling durations using sulfuric acid as a catalyst in mechanocatalysis. Likewise, oxalic acid dihydrate and potassium pyrosulfate as a novel catalyst, successfully converted barley straw to reducing sugars (42.4 wt% and 39.7 wt%, respectively), however longer milling durations were required. In comparison, lower saccharification (<10 wt%) was obtained by employing formic acid and acetic acid in mechanocatalysis. Harsh milling conditions initiated a temperature increase within the reaction vessel resulting in enhanced sugar release. Likewise, greater sugar release was observed with increased catalyst amount and acidity. The results revealed that the balance of these factors is crucial for efficient catalytic conversion of barley strawTiivistelmä Biomassan konvertointimenetelmät mahdollistavat biotalouden hengen mukaisesti uusia ratkaisuja kemikaalien ja materiaalien kestävään tuotantoon sekä biomassan energiakäyttöön eri muodoissa (kuten pelletit, biopolttoaineet ja biokaasu). Lignoselluloosapohjaista, uusiutuvaa biomassaa, kuten tässä työssä tutkittua ohran olkea, on runsaasti saatavilla. Lignoselluloosa onkin yksi lupaavimmista raaka-aineista korvaamaan fossiilisia polttoaineita ja vähentämään kasvihuonekaasupäästöjä. Väitöskirjatutkimus antaa uutta tietoa ohran oljen mekaanis–katalyyttisestä käsittelystä, mikä on suhteellisen uusi menetelmä biomassan katalyyttisessä muokkauksessa. Menetelmässä yhdistetään kemiallinen katalyysi ja mekaaninen muokkaus (jauhatus) kuulamyllyllä. Lignoselluloosa (ohran olki) impregnoitiin tai sekoitettiin tutkitun katalyytin (muurahaishappo, etikkahappo, rikkihappo, oksaalihappodihydraatti, kaliumpyrosulfaatti) kanssa ja käsiteltiin erilaisissa mekaanis–katalyyttisissä olosuhteissa. Lignoselluloosan selektiivinen depolymerointi muodosti vesiliukoisia oligosakkarideja ja edelleen hydrolyysin kautta pelkistyneitä sokereita (pääasiassa ksyloosia, galaktoosia, arabinoosia ja glukoosia), joita voidaan käyttää biopolttoaineiden ja -kemikaalien valmistuksessa. Tutkimuksen tulosten perusteella rikkihappokatalyytillä saatiin 53,4 massa-% ohran oljen sisältämistä pelkistyneistä sokereista vapautettua lyhyillä käsittelyajoilla. Lisäksi sivutuotteiden muodostuminen oli vähäistä. Vastaavasti oksaalihappodihydraatti (sokerisaanto 42,4 massa-%) ja kaliumpyrosulfaatti (sokerisaanto 39,7 massa-%) toimivat uusina katalyytteinä hyvin, mutta vaativat rikkihappokatalyyttiä pidemmät jauhatusajat. Sen sijaan muurahaishapolla ja etikkahapolla sokerisaanto oli erittäin alhainen (alle 10 massa-%) mekaanis–katalyyttisessä käsittelyssä. Tutkimuksessa todettiin, että voimakas jauhatus vaikutti selkeästi reaktiolämpötilan nousuun käsittelyn aikana, mikä edisti korkeampaa sokerisaantoa. Vastaavasti sokerisaantoa voitiin parantaa katalyyttimäärällä ja happamuudella. Tulokset osoittavat, että näiden muuttujien tasapaino on ratkaisevaa ohran oljen tehokkaan katalyyttisen muuntamisen kannalta
27
Hatt, Juliette W. "Pretreatment options for municipal wastewater reuse using membrane technology". Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/10200.
Testo completoAbstract (sommario):
Increasing freshwater scarcity across the world means that wastewater reclamation is being considered as a key method in which to meet the growing demand. Evolution of water reuse schemes where high quality product is required such as for indirect potable reuse has led to the adoption in recent years of the integrated membrane scheme using a combination of microfiltration or ultrafiltration with reverse osmosis membrane. However, despite technological advancements, these membranes are still prone to fouling resulting in increased costs through cleaning or replacement. This thesis aims to look at pretreatment to reduce the fouling propensity of the microfiltration membranes via a 600m3 /d pilot plant which was commissioned to investigate indirect potable reuse. A range of pretreatments including pre-screening, pre-coagulation, powdered activated carbon and granular activated carbon were assessed based on fouling amelioration, water quality improvement and cost analysis. Results showed that ferric sulphate dosing was the most effective in terms of reducing the reversible fouling rate especially at high turbidity loads enabling higher flux to be realised leading to a small cost benefit. Activated carbon proved the most effective pretreatment in terms of organic removal and a significant reduction in the irreversible fouling rate. However, the cost involved in using this as a pretreatment is significant compared to possible cost savings through reduced requirement for chemical cleaning. This pretreatment is only viable if it obviates the need for a separate organic removal process.
28
Ramos, Luiz Pereira. "Steam pretreatment and enzymatic hydrolysis of Eucalyptus viminalis chips". Thesis, University of Ottawa (Canada), 1992. http://hdl.handle.net/10393/7749.
Testo completoAbstract (sommario):
The steam pretreatment of Eucalyptus viminalis chips was characterized. Pretreatment parameters such as steam temperature, residence time, addition of SO$\sb2$ as an acid catalyst, and initial moisture content of the chips were evaluated in order to optimize recovery, fractionation and enzymatic hydrolysis of pretreated materials. In the absence of an acid catalyst, the best pretreatment was obtained at 230$\sp\circ$C for 120 s using chips with a moisture content of 50% (w/w). Pretreatment by steam explosion showed no variation resulting from differences in the initial moisture content of the chips. However, when the substrate was steam-treated without explosion, the initial moisture content of the chips had a significant influence on the recovery yield and the degree of enzymatic hydrolysis. When the chips were impregnated with sulfur dioxide (1% SO$\sb2$, w/w) prior to steaming, milder pretreatment conditions of 210$\sp\circ$C for 50 s were sufficient because of the catalytic action of the SO$\sb2$ gas. SO$\sb2$ catalysis was shown to be particularly beneficial for the steam explosion of green chips. More than 95% of the original cellulose could be hydrolysed to glucose with more than 90% of the original pentosan recovered as xylose in the water-soluble fraction. It appeared that the efficient uptake of the SO$\sb2$ catalyst was dependent on the initial moisture content of the chips. Enzymatic hydrolysis of SO$\sb2$-impregnated, steam-treated E. viminalis was carried out with increasing substrate concentrations and enzyme loadings. Removal of the alkali-soluble lignin had a minor effect on the hydrolysis yield when both the substrate concentration and enzyme loading were calculated in relation to the cellulose content. The mode of action of Trichoderma cellulases was further investigated by looking at changes which occurred in the morphology and fine structure of the cellulosic substrate during hydrolysis. A rapid reduction in fiber length (fragmentation), followed by an almost complete saccharification of cellulose, was observed for several fractions derived from pretreated eucalyptus. A gradual decrease in the degree of polymerisation (DP) of the SO$\sb2$-SEE-WIA/$\rm H\sb2O\sb2$ fraction reflected the high susceptibility of this substrate to hydrolysis. However, when the influence of hydrolysis on the DP of a fully bleached kraft pulp derived from eucalyptus was investigated, there was no noticeable change in the DP distribution of the residue until 24 h of hydrolysis. It seemed that the mode of action of Trichoderma cellulases varied depending on the type of pretreated substrate that was hydrolysed. As hydrolysis resulted in a gradual decrease in both the degree of polymerisation (DP) and the degree of crystallinity of the F-150 fraction, it was apparent that the depolymerisation of this substrate was predominantly due to exoglucanase activity. By contrast, the enzymatic hydrolysis of the FBEP-48 fraction resulted in little change in either the cellulose DP or the degree of crystallinity of the substrate. This suggested a "peeling off" type of mechanism. The susceptibility of the pretreated substrates to enzymatic hydrolysis could not be easily predicted from the differences in their cellulose DP or crystallinity. (Abstract shortened by UMI.)
29
Almlöf, Ambjörnsson Heléne. "Mercerization and Enzymatic Pretreatment of Cellulose in Dissolving Pulps". Doctoral thesis, Karlstads universitet, Institutionen för ingenjörs- och kemivetenskaper, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-26960.
Testo completoAbstract (sommario):
This thesis deals with the preparation of chemically and/or enzymatically modified cellulose. This modification can be either irreversible or reversible. Irreversible modification is used to prepare cellulose derivatives as end products, whereas reversible modification is used to enhance solubility in the preparation of regenerated cellulose. The irreversible modification studied here was the preparation of carboxymethyl cellulose (CMC) using extended mercerization of a spruce dissolving pulp. More specifically the parameters studied were the effect of mercerization at different proportions of cellulose I and II in the dissolving pulp, the concentration of alkali, the temperature and the reaction time. The parameters evaluated were the degree of substitution, the filterability and the amount of gel obtained when the resulting CMC was dissolved in water. Molecular structures of CMC and its gel fractions were analysed by using NIR FT Raman spectroscopy. It was found that the alkali concentration in the mercerization stage had an extensive influence on the subsequent etherification reaction. FT Raman spectra of CMC samples and their gel fractions prepared with low NaOH concentrations (9%) in the mercerization stage indicated an incomplete transformation of cellulose to Na-cellulose before carboxymethylation to CMC. Low average DS values of the CMC, i.e. between 0.42 and 0.50 were obtained. Such CMC dissolved in water resulted in very thick and semi solid gum-like gels, probably due to an uneven distribution of substituents along the cellulose backbone. FT Raman spectra of CMC samples and their gel fractions mercerized at higher alkaline concentration, i.e. 18.25 and 27.5% in the mercerization stage, indicated on the other hand a complete transformation of cellulose to Na-cellulose before carboxymethylation to CMC. Higher average DS values of the CMC, i.e. between 0.88 and 1.05 were therefore obtained. When dissolved in water such CMC caused gel formation especially when prepared from dissolving pulp with a high fraction of cellulose II. The reversible modification studied was the dissolution of cellulose in NaOH/ZnO. Here the effect of enzyme pretreatment was investigated by using two mono-component enzymes; namely xylanase and endoglucanase, used in consecutive stages. It was found that although the crystallinity and the specific surface area of the dissolving pulp sustained minimal change during the enzymatic treatment; the solubility of pulp increased in a NaOH/ZnO solution from 29% for untreated pulp up to 81% for enzymatic pretreated pulp.Baksidetext Cellulose can be chemically and/or enzymatically modified. Irreversible modification is used to prepare cellulose derivatives as end products, reversible modification to enhance solubility in the preparation of regenerated cellulose. The irreversible modification studied here was the preparation of carboxymethyl cellulose (CMC) using extended mercerization of a spruce dissolving pulp. More specifically the parameters studied were the effect of mercerization at different proportions of cellulose I and II in the dissolving pulp, the concentration of alkali, the temperature and the reaction time. It was found that the alkali concentration in the mercerization stage had an extensive influence on the subsequent etherification reaction. The content of cellulose II had little effect on degree of substitution (DS) at low NaOH concentration, but tended to decrease DS at higher NaOH concentration in both cases compared with cellulose I. It was also found that the content of cellulose II correlates with the gel formation obtained when the CMC is dissolved in water. The reversible modification studied was the dissolution of cellulose in NaOH/ZnO. Here the effect of enzyme pretreatment was investigated by using two mono-component enzymes; namely xylanase and endoglucanase, used in consecutive stages. It was found that the solubility of pulp increased in a NaOH/ZnO solution from 29% for untreated pulp up to 81% for enzymatic pretreated pulp.
30
Ruffell, John. "Pretreatment and hydrolysis of recovered fibre for ethanol production". Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/1369.
Testo completoAbstract (sommario):
Energy utilization is a determining factor for the standards of living around the world, and the current primary source of energy is fossil fuels. A potential source of liquid fuels that could ease the strain caused by diminishing petroleum resources is bioethanol.
Effective exploitation of biomass materials requires a pretreatment to disrupt the lignin and cellulose matrix. The pretreatment utilized for this research was oxygen delignification, which is a standard process stage in the production of bleached chemical pulp.
The model substrate utilized as a feedstock for bioethanol was recovered fibre. An analysis of the substrates digestibility resulted in a hexose yield of approximately 23%, which justified the need for an effective pretreatment.
An experimental design was performed to optimize the delignification conditions by performing experiments over a range of temperature, caustic loadings, and reaction times. Equations were developed that outline the dependence of various response parameters on the experimental variables. An empirical model that can predict sugar concentrations from enzymatic hydrolysis based on the Kappa number, enzyme loading, and initial fibre concentration was also developed.
A study of hydrolysis feeding regimes for untreated recovered fibre (87 Kappa), pretreated recovered fibre (17 Kappa), and bleached pulp (6 Kappa) showed that the batch feeding regime offers reduced complexity and high sugar yields for lower Kappa substrates.
In order to evaluate the possibility of lignin recovery, the pH of delignification liquor was reduced by the addition of CO₂ and H₂SO₄, resulting in up to 25% lignin yield. An experiment that looked at effect of post-delignification fibre washing on downstream hydrolysis found that a washing efficiency of approximately 90% is required in order to achieve a hexose sugar yield of 85%.
31
Tooyserkani, Zahra. "Hydrothermal pretreatment of softwood biomass and bark for pelletization". Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44652.
Testo completoAbstract (sommario):
Densification can resolve the logistical challenges encountered when large volumes of biomass are required for conversion processes to benefit from economies-of-scale. Despite the higher density of pellets, they easily disintegrate into fines due to impact or moisture sorption during handling and storage. Fines accumulation can lead to explosion, off-gassing and self-combustion, threatening the occupational health and safety of the workers. The current study investigates the use of several hydrothermal pretreatments to improve pellet quality in terms of mechanical strength and moisture sorption resistance, while lowering energy input during size reduction, drying and densification steps. Pretreatment of ground softwood particles (Pine, Spruce, Douglas fir whitewood and bark) with external saturated steam at 220°C for 5 min resulted in the higher calorific values, higher hydrophobicity and higher carbon percentage. These changes along with the dark brownish colour of steam treated material indicated a mild degree of torrefaction when compared to dry torrefaction at higher temperatures. Despite a slightly lower density, the mechanical strength of pellets made of steam treated particles increased considerably. Mechanical energy input for pelletization of treated material was higher than the untreated pellets when compressed under the same force for all species and bark samples.
Hydrothermal pretreatment of wet Douglas fir wood particles, by steam generated from the moisture inside the material, resulted in the same characteristics as those obtained from pretreatments by external steam. Increased treatment temperature increased the hydrophobicity compared to untreated pellets.
Sulfur-dioxide catalyzed steam pretreatment substantially reduced the particle size of Douglas fir woodchips, eliminating any further grinding requirement for pelletization. The SO₂-catalyzed steam treated pellets had a higher density and exhibited a two-time higher mechanical strength compared to untreated pellets. Despite a higher moisture adsorption capacity than the untreated, treated pellets remained intact under highly humid (30°C, 90% RH) conditions. The high heating values, low ash content and good overall carbohydrate recovery of SO₂-catalyzed steam treated pellets indicate their potential suitability for both biochemical and thermo-chemical applications.
32
Kitsos, Haralambos Minas. "Swelling pretreatment of lignocellulosic materials to promote enzymatic hydrolysis". Thesis, Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/11780.
Testo completo
33
Aslanzadeh, Solmaz. "Pretreatment of cellulosic waste and high rate biogas production". Doctoral thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-3684.
Testo completoAbstract (sommario):
The application of anaerobic digestion technology is growing worldwide, mainly because of its environmental benefits. Nevertheless, anaerobic degradation is a rather slow and sensitive process. One of the reasons is the recalcitrance nature of certain fractions of the substrate (e.g., lignocelluloses) used for microbial degradation; thus, the hydrolysis becomes the rate-limiting step. The other reason is that the degradation of organic matter is based on a highly dynamic, multi-step process of physicochemical and biochemical reactions. The reactions take place in a sequential and parallel way under symbiotic interrelation of a variety of anaerobic microorganisms, which all together make the process sensitive. The first stage of the decomposition of the organic matter is performed by fast growing (hydrolytic and acid forming) microorganisms, while in the second stage the organic acids produced are metabolized by the slow growing methanogens, which are more sensitive than the acidogens; thus, methanogenesis becomes the rate-limiting step. The first part of this work evaluates the effects of a pretreatment using an organic solvent, N-methylmorpholine-N-oxide (NMMO), on cellulose-based materials in order to overcome the challenge of biomass recalcitrance and to increase the rate of the hydrolysis. NMMO-pretreatment of straw separated from the cattle and horse manure resulted in increased methane yields, by 53% and 51%, respectively, in batch digestion tests. The same kind of pretreatment of the forest residues led to an increase by 141% in the methane production during the following batch digestion assays. The second part of this work evaluates the efficacy of a two-stage process to overcome the second challenge with methanogenesis as the rate-limiting step, by using CSTR (continuous stirred tank reactors) and UASB (up flow anaerobic sludge blanket) on a wide variety of different waste fractions in order to decrease the time needed for the digestion process. In the two-stage semi-continuous process, the NMMO-pretreatment of jeans increased the biogas yield due to a more efficient hydrolysis compared to that of the untreated jeans. The results indicated that a higher organic loading rate (OLR) and a lower retention time could be achieved if the material was easily degradable. Comparing the two-stage and the single-stage process, treating the municipal solid waste (MSW) and waste from several food processing industries (FPW), showed that the OLR could be increased from 2 gVS/l/d to 10 gVS/l /d, and at the same time the HRT could be decreased from 10 to 3 days, which is a significant improvement that could be beneficial from an industrial point of view. The conventional single stage, on the other hand, could only handle an OLR of 3 gVS/l/d and HRT of 7 days.
34
Dastjerdi, R., e V. Babaahmadi. "Nanowire fabrication on cotton surfaces: effect of the pretreatment". Thesis, Видавництво СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20631.
Testo completoAbstract (sommario):
Anisotropic nanostructures such as nano-wires, nano-tubes, nano-rods, nanoribbons,
nano-layers, etc. are extremely attracted due to their larger surface area as
compared to nano-particles. This research has targeted at fabrication of the metallic
nano-wires through a simple one-step pad-dry method. The effects of mercerizing as one
of the most common and important finishing treatments on cotton fabrics have been
investigated. Mercerized and un-mercerized fabrics with the same structures have been
treated and compared. SEM micrographs confirmed fabrication of the nano-wires with a
high aspect ratio on the fiber surfaces oriented parallel with fiber axes. An enhanced
potentiality for growing nano-wires with higher level of orientation has been observed
for mercerized fabrics compared to un-mercerized ones. As it is well known, mercerizing
can cause some structural changes in cotton fibers. Reduction of crystallinity as a
result of this process (mercerizing) leads to increasing the amorphous regions which
have a good potentiality for growing nano-structured materials. The higher moisture
regains, absorbency, smoother morphology, etc. caused by mercerizing can direct the
better growth of nano-structures on mercerized fabrics.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/20631
35
Wang, Yimin. "Pretreatment, Morphology and Properties of Organosilane Anti-Corrison Coatings". University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1186412600.
Testo completo
36
Shi, Kang. "Electrochemical pretreatment of carbon electrodes and the electroanalytical applications". HKBU Institutional Repository, 2000. http://repository.hkbu.edu.hk/etd_ra/271.
Testo completo
37
Ho, Yee Man. "Development of sample pretreatment methods for complex analytical matrices". HKBU Institutional Repository, 2013. http://repository.hkbu.edu.hk/etd_ra/1510.
Testo completo
38
Siddaramu, Thara Gejjalagere. "EVALUATION OF DIFFERENT PRETREATMENT APPROACHES FOR DISRUPTING LIGNOCELLULOSIC STRUCTURES". OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/703.
Testo completoAbstract (sommario):
AN ABSTRACT OF THE THESIS OF Thara G. Siddaramu, for the Master of Science degree in Civil and Environmental Engineering, presented on February 5, 2011, at Southern Illinois University Carbondale. TITLE: EVALUATION OF DIFFERENT PRETREATMENT APPROACHES FOR DISRUPTING LIGNOCELLULOSIC STRUCTURES MAJOR PROFESSOR: Dr. Yanna Liang There are two major steps in biofuel production- pretreatment of lignocellulosic materials and enzymatic hydrolysis. The present study investigated the ability of two pretreatment methods, namely traditional oven and microwave oven treatments for disrupting lignocellulosic structures. The substrates tested were Jatropha seed cake and sweet sorghum bagasse. In recent years, Jatropha curcas also known as physic nut or purging nut has attracted extensive attention due to its several unique characteristics. Similarly, sweet sorghum has the potential to provide great value to energy sectors and food industries being that the entire plant is rich in various sugars and nutrients. Both crops can adapt to various climates, and can withstand extended drought conditions compared to other crops. Additionally, both Jatropha seed cakes and sweet sorghum bagasse are good sources of lignin and carbohydrates, which could be used for production of biofuels only if the sugars can be unlocked. Several treatment methods such as mechanical, physical, chemical and biological treatments have been reported to breakdown the cellulosic structure of biomass. However, other low cost and quicker methods, such as ovenpretreatment and microwave irradiation have not been evaluated for Jatropha seed cake and Sweet Sorghum Bagasse (SSB), respectively. Composition change of Jatropha seed cake samples was evaluated upon lime pretreatment at 100 oC with different parameters. With a lime dose of 0.2 g and a water content of 10 ml per gram of cake and a treatment period of 1 h, 38.2 ± 0.6% of lignin was removed. However, 65 ± 16% of hemicellulose was also lost under this condition. For all the treatments tested, cellulose content was not affected by lime supplementation. Through further examining total reducing sugar (TRS) release by enzymatic hydrolysis after lime pretreatment, results indicated that 0.1 g of lime and 9 ml of water per gram of cake and 3 h pretreatment produced the maximal 68.9% conversion of cellulose. Without lime pretreatment, the highest cellulose conversion was 33.3%. Finally, this study shows that Jatropha seed cake samples could be hydrolyzed by enzymes. Even though the cellulose content was not high for this Jatropha cake sample, the fractionation by lime presented in this study opened the door for other applications, such as removal of lignin and toxicity for use as animal feed and fertilizer. The microwave radiation pretreatment of SSB was evaluated with or without lime (0.1 g/g bagasse) at 10 ml water/g bagasse for 4 min. TRS release over 72-h enzymatic hydrolysis was different for samples treated differently and at different solid loadings. The TRS concentration was increased by 2 and 5-fold from 0 to 24 hours in non lime-pretreated and lime-pretreated samples, respectively. Further incubation of samples for 48 and 72 h did not result in increased TRS. Comparing different solid loadings of samples treated with or without lime, 1% solid content resulted in 1.4 times higher TRS increase than that of 5% solid concentration. Therefore, lime was effective in disintegrating lignocellulosic structures and making cellulose more accessible for saccharification. Higher solid loadings which can lead to higher sugar concentrations are desired for downstream biofuel production. But, as shown in this study, higher concentration of bagasse samples decreased rate of cellulose hydrolysis due to poorer mixing efficiency and hindrance to interactions between enzymes and solid materials. Thus, an optimal solid content needs to be determined for maximal cellulose hydrolysis and for preparing the hydrolysates for downstream processes, either bioethanol or lipid production.
39
Cheng, Lei. "Lignin Degradation and Dilute Acid Pretreatment for Cellulosic Alcohol Production". University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1282329715.
Testo completo
40
Holm, J. (Jana). "Catalytic pretreatment and hydrolysis of fibre sludge into reducing sugars". Doctoral thesis, Oulun yliopisto, 2013. http://urn.fi/urn:isbn:9789526202839.
Testo completoAbstract (sommario):
Abstract Decreasing oil reserves, the need to reduce CO2 emissions and increasing energy demand are issues that are forcing scientists to search for new opportunities in the field of energy. As a result, biofuels have been considered as one possible solution to solve part of these challenges. This research is one small part of that effort. For both human and economic reasons the use of edible raw materials for biofuel production is not sustainable. This study aims to convert forest industry waste, namely fibre sludge, into reducing sugars (glucose). This platform chemical can then be converted to value-added products, biofuels such as ethanol or butanol for example. Depolymerisation of fibre sludge (cellulose) to glucose monomers was performed firstly by pretreatment with ionic liquids [BMIM]Cl and [AMIM]Cl and secondly hydrolysed by acids (dilute maleic and sulphuric acids) and enzymes. To go further with the research the two pretreatment steps, dissolution and hydrolysis were combined into a one-step reaction by using a task-specific ionic liquid [SBMIM]Cl. With the ionic liquid [AMIM]Cl used for pretreatment in this study, we were able to recover 85% of sugars relative to the initial dry mass of the fibre sludge. Corresponding yield was about 30% without pretreatment. The task-specific ionic liquid [SBMIM]Cl was able to dissolve and hydrolyse fibre sludge in a one-step reaction. This ionic liquid was also able to dissolve wet fibre sludge with a moisture content of up to 50%. Enzymatic hydrolysis of [AMIM]Cl pretreated fibre sludge showed also very promising yields of reducing sugarsTiivistelmä Biotaloudessa keskeisiä globaaleja haasteita ovat kasvava energiantarve, vähenevät fossiiliset öljyvarannot sekä tarve vähentää energiantuotannon ja liikenteen hiilidioksidipäästöjä, mikä on lisännyt viime vuosina aktiivisuutta biopolttoainetutkimuksen saralla. Biopolttoaineet voidaankin nähdä eräänä mahdollisuutena lisätä uusiutuvien luonnonvarojen käyttöä sekä siten edistää vähähiilistä taloutta. Uusien kestävän kehityksen periaatteita noudattavien energiantuotantomenetelmien kehittämisessä on suosittava biomassoja, jotka eivät kilpaile ruoantuotannon kanssa samoista raaka-aineista. Tässä suhteessa erityisen keskeisessä asemassa ovat mm. teollisuuden sivutuotteet, joita myös tässä työssä on tutkittu. Väitöskirjatutkimuksessa biomassaraaka-aineena on käytetty selluteollisuuden sivutuotteita, erityisesti kuitulietettä. Kuitulietteessä on korkea selluloosa- ja hemiselluloosapitoisuus, minkä vuoksi se soveltuisi ns. platform-kemikaalien valmistuksen raaka-aineeksi ja edelleen arvokkaiden kemikaalien ja polttoaineiden valmistukseen. Tutkimuksessa tavoitteena on ollut kuitulietteen sisältämien polymeerien liuottaminen ja hydrolyysi pelkistyneiksi sokereiksi, erityisesti glukoosiksi, mahdollisimman korkealla saannolla. Kuitulietteen, kuten yleensäkin selluloosan, haasteena on sen niukkaliukoisuus perinteisiin liuottimiin. Tämän vuoksi kuitulietettä esikäsiteltiin ionisissa liuottimissa ([BMIM]Cl ja [AMIM]Cl), jotta depolymerisaatio glukoosimonomeereiksi olisi mahdollinen korkealla saannolla. Esikäsittelyn jälkeen hydrolyysi tehtiin joko laimealla hapolla tai entsymaattisesti. Esikäsittelyä tutkittiin myös ns. spesifisessä ionisessa liuottimessa ([SBMIM]Cl), jossa kuitulietteen liukeneminen ja hydrolyysi tapahtuivat yhdessä vaiheessa. Esikäsittely [AMIM]Cl:ssa mahdollisti sen, että alkuperäisen kuivan kuitulietteen sokereista saatiin talteen 85 % entsymaattisen hydrolyysin jälkeen. Ilman esikäsittelyä vastaava saanto oli noin 30 %. Ionineste, [SBMIM]Cl, onnistui liuottamaan ja hydrolysoimaan kuitulietteen yhdessä vaiheessa, tosin sokerisaannot jäivät alhaisiksi. Märkä kuituliete, jonka kosteuspitoisuus oli 50 %, liukeni myös tähän ioninesteeseen
41
Wallen, William Jack. "Substrate enhancement utilizing ribose pretreatment in normal and pathologic states". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ34093.pdf.
Testo completo
42
Feld, Rachel Penny. "Pretreatment motivational enhancement therapy for eating disorders, a pilot study". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0004/MQ46110.pdf.
Testo completo
43
Wang, Wei-Chi. "Salt diffusion into vegetative tissue as pretreatment in ohmic heating". Connect to resource, 1991. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1195576576.
Testo completo
44
Kanchanalai, Pakkapol. "New dehydration and pretreatment process for ethanol production from biomass". Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53559.
Testo completoAbstract (sommario):
The cost of pretreatment process for saccharification from biomass and the cost of dilute ethanol purification are significant components of the overall cost for fuel grade ethanol production through fermentation or other biological routes. This work focuses on developing optimal designs of dilute ethanol purification process and the new acid hydrolysis technology for the production of fermentable sugars from biomass where the overarching goal is to reduce the cost of ethanol production from biomass. In this thesis, the ethanol separation process with the reverse osmosis membrane pretreatment is developed to reduce separation cost and energy consumption especially when the feed is dilute. In addition, the new solid phase reactive separation system for biomass saccharification via acid hydrolysis is proposed. This new process is applied for both dilute and concentrated acid hydrolysis where the goal is to increase sugar yield and to reduce byproduct formation. The reaction kinetics of the concentrated acid hydrolysis is investigated through batch experiment. All of these use optimization approaches for seeking the best process designs and for parameter estimations.
45
Kvillborn, Carin. "Enzymatic Pretreatment of Lignocellulose Rich Waste for Improved Biogas Production". Thesis, Linköpings universitet, Tema vatten i natur och samhälle, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-104974.
Testo completoAbstract (sommario):
The present study aimed to investigate the methane yield from anaerobic digestion of a lignocellulosic substrate subjected to different pretreatments. The lignocellulosic forest residues materials were milled and then pretreated with the organic solvent NMMO (N-Methylmorpholine N-oxide) and/or the lignolytic enzymes laccase and versatile peroxidase at a dosage of 60 U g-1 total solids (TS) substrate. The amount of methane produced was studied in a biomethane potential assay with inocula from a thermophilic biogas reactor treating municipal waste. All samples were run in triplicates. Due to the large amount of samples, two biomethane potential assays were conducted: series 10 & 20 and series 30 & 40. The gas production results show that NMMO-treated forest residues yielded 130 NmL CH4 g-1 volatile solids (VS) substrate and the untreated forest residues yielded 95 NmL CH4 g-1 VS substrate for series 10 & 20. For series 30 & 40, both untreated and NMMO-treated forest residues yielded 140 NmL CH4 g-1 VS substrate. NMMO-treatment appears to be favourable and no advantages from the enzyme pretreatment could be seen in terms of gas yield. An analysis of the reaction fluid after the enzymatic treatment showed presence of phenols, an indication of successful lignin hydrolysis.Studien avsåg att undersöka metanutbytet från anaerob nedbrytning med förbehandlad lignocellulosa som substrat. Lignocellulosamaterialet, i form av skogsavfall, maldes och förbehandlades därefter med det organiska lösningsmedlet NMMO (N-metylmorfolin-N-oxid) och/eller de lignolytiska enzymerna laccase och versatile peroxidas med dosen 60 U g-1 torrsubstanshalt (TS). Mängden producerad metan undersöktes i en biometanpotentialanalys med inocula från en termofil biogasreaktor, som behandlade hushållsavfall. Triplikat av varje prov användes för att öka den statistiska stabiliteten. På grund av det stora antalet prover genomfördes studien i två omgångar: Serie 10 & 20 samt serie 30 & 40. Resultaten visade att det NMMO-behandlade skogsavfallet gav 130 NmL CH4 g-1 organisk substans (VS) och det obehandlade skogsavfallet gav 95 NmL CH4 g-1 VS i serie 10 & 20. Både obehandlat och NMMO- behandlat skogsavfall gav 140 NmL CH4 g-1 VS i serie 30 & 40. Förbehandling med NMMO verkar vara fördelaktig medan enzymbehandling endast resulterade i en smärre ökning av gasproduktionen. En analys av vätskan efter enzymbehandlingen visade förekomst av fenoler, vilket visar på en lyckad ligninnedbrytning.
46
Li, Sam King Ho. "Empirical kinetic modeling of oxygen delignification pretreatment of wheat straw". Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44773.
Testo completoAbstract (sommario):
With diminishing supplies of oil reserves and surging oil prices, research on renewable and sustainable energy has significantly increased. Biofuels have shown their potential in replacing traditional fossil fuels, such as gasoline. Second generation biofuels that use nonfood lignocellulosic biomass to produce bioethanol have been identified as one of these renewable sources.
Oxygen delignification has been identified as an effective pretreatment method for agricultural waste, such as wheat straw, to increase the enzymatic hydrolysis yield. The purpose of this study was to develop a kinetic model for the delignification of wheat straw.
An experimental design was planned to enable the development of an empirical model of the reaction kinetics for oxygen delignification of wheat straw. This was accomplished by studying the effects of substrate loading (2-4% w/w), reaction temperature (90-130°C) and caustic loading (5-15% w/w). From the experiments, an empirical model that can predict the lignin content of wheat straw after oxygen delignification pretreatment based on reaction temperature, caustic loading and lignin content was developed:
(d[L])/dt= -k_L 〖[L]〗^(a₁) (k'([L]-[L₀])+[〖OH^-₀]〗)^(a₂)
Where:
kL = kinetic constant of lignin
k’ = constant for the relationship between kinetic constant of lignin and hydroxide ion
L = concentration of lignin in substrate
L0 = concentration of initial lignin substrate
OH0- = concentration of hydroxide ion
a1 = reaction order for lignin
a2 = reaction order for hydroxide ion
The pretreated substrate was analyzed and showed increased sugar concentration and sugar yield when subjected to enzymatic hydrolysis at 20 FPU/g glucan. It was also found that caustic loading would become saturated when it was above 10-12% w/w. Out of all the operating parameters, caustic loading had the greatest effect on lignin solubilization, carbohydrate recovery and sugar yield.
An economic analysis on the oxygen delignification pretreatment process was performed with Aspen Plus and Aspen Economic Analyzer. Using sugar produced as a basis, it was found that the pretreatment cost was 26.20 ¢/lb sugar. A sensitivity analysis was also performed on the cost of biomass, caustic (NaOH), and enzyme. It was concluded that the cost of enzyme had the most significant effect on the cost of pretreatment.
47
Wahidunnabi, Abdullahil Kafi Md. "Temperature phased anaerobic sludge digestion with high pressure homogenization pretreatment". Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46126.
Testo completo
48
Li, Yu-Sheng, e 李郁昇. "Pretreatment of septage". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/24727322199079148044.
Testo completoAbstract (sommario):
碩士逢甲大學
土木及水利工程研究所
86
The effect of septage pretreatment was studied. The pretreatment methodsused include thermal treatment and addition of HCl, NaOH, FeCl3, alum or poly aluminum chloride (PAC). Granular sludge of upflow anaerobic sludge blanket (UASB) (Hydraulic retention times, 1.5 days) was used in serum vials to investigate the effects of the pretreatment on the anaerobic ammonium oxidation (ANAMMOX) and anaerobic digestion. About 20% of raw septage was directly used in farm in Taiwan. Chemical treatments can reduce the pollution in farming usage of septage. From evaluation of the dewaterability, sludge volume, COD removal efficiency, stability, fertilization and the capital of reagent, the optimal operationconditions were pH 5 and rapid mixing (1 min) with a ferric chloride dosageof 1800 mg/L. The capillary suction time (CST), sludge volume, fertilization(TP,TN) and the chemical cost were 27sec, 153ml, 20.2μg/mg, 2.07μg/mg andNT 23.4 dollars per ton, respectively. Pretreatment with HCl (60 meq/L), NaOH (60 meq/L) and heat (175℃, 1.5hrs)resulted in 225, 825 and 430% increases in SCOD. Treatment with lime(1500 mg/L), FeCl3 (1800 mg/L), alum (4000 mg/L) and PAC (800 mg/L) allowed64, 92, 91 and 57% removal efficiency in dewaterability. Denitrification by ANAMMOX occurred in vials assays. The nitrogen gasproduction, specific nitrogen gas production and, CST of row septage were16.46 mL, 199.5 mLN2/gCOD and 183sec respectively. The variation of nitrogengas production were -83, -42, -52, -16, 24 and 31%, respectively, whilespecific nitrogen gas production increased 34, 26, 30, 300, 296 and 81%.The CST decreased 16, 69, 22, 61, 61 and 54% for heat, HCl, NaOH, FeCl3,alum and PAC, respectively. Alum pretreatment enhanced the ammonia removaland dewaterability. Tas the most significanthe effect of Ni2+ on ANAMMOX was the most significant among the heavy metals tested.
49
"Electrospun Pretreatment Membranes". Master's thesis, 2020. http://hdl.handle.net/2286/R.I.62710.
Testo completoAbstract (sommario):
abstract: Managing water resources has become one of the most pressing concerns of scientists both in academia and industry. The reverse osmosis (RO) water treatment process is a well-researched technology among the pressure driven processes to produce potable water. RO is an energy intensive process and often RO membranes are susceptible to fouling and scaling that drives up operational cost and hinder the efficiency. To increase the performance of RO membranes the feed water is pretreated to remove pollutants before desalination. This work aims to fabricate pretreatment membranes to prevent the effects of fouling and scaling by introducing hydrophilic character to membrane. This work explores electrospinning, a cost-effective and scalable technique, to blend two polymers into a nonwoven membrane comprised of fibers ~100 nm - 10 µm in diameter.
A rotary drum collector holding the mat was used to simultaneously collect the electrospun hydrophobic poly(vinyl chloride) (PVC) and hydrophilic poly(vinyl alcohol) (PVA) fibers from two separate solutions. The hydrophilicity of the resulting membrane was tuned by controlling the relative deposition rate of PVA onto the co-spun mat. Fiber diameter and morphologies were characterized by scanning electron microscopy, and Fourier-transform infrared spectroscopy and Confocal fluorescence microscopy further confirmed the presence of both polymers. Moreover, a rigorous analysis to map the PVA/PVC concentration was established to accurately report the relative concentrations of the two polymers on the co-spun mat. After electrospinning, the PVA in the co-spun mats were cross-linked with poly(ethylene glycol) diacid to impart mechanical strength and tune the porosity.
EDS analysis revealed inconsistencies in the mass deposition of both polymers suggesting an improvement in the current experimental design to establish a meaningful relationship between PVA concentration and hydrophilicity. However, tensile test revealed that co-spun mats with high mass flow ratios of PVA possessed high mechanical strength showing a significant improvement in the Young’s Modulus. Furthermore, the co-spun mats were challenged with filtration experiments expecting a positive correlation of flux with PVA concentration. But it was found that with increased concentration, crosslinked PVA constricted PVC fibers minimizing the pores causing a lower flux and a dense membrane structure suitable for filtration.Dissertation/Thesis
Masters Thesis Chemical Engineering 2020
50
Timmes, Thomas Charles Dempsey Brian A. "Electrocoagulation pretreatment prior to ultrafiltration". 2009. http://etda.libraries.psu.edu/theses/approved/PSUonlyIndex/ETD-3748/index.html.
Testo completo