Water and energy share an important relationship since it takes water to produce energy, and likewise, energy to pump, treat, and distribute water. This thesis explores the energy-water nexus in regards to electricity and transportation fuel production, as well as water treatment. It investigates how the Energy Independence and Security Act of 2007 might affect this interrelationship in the future since increases in corn cultivation for biofuels production are likely to lead to higher nitrate concentrations in US water reservoirs, which could trigger the requirement for additional energy consumption for drinking water treatment. The analysis indicates that advanced drinking water treatment might require an additional 2360 million kWh annually to treat drinking water currently exceeding the Environmental Protection Agency’s maximum contaminant level (MCL) limit of 10 mg per liter of nitrate-nitrogen. This is a 2100% increase in energy consumption for advanced water treatment to meet this MCL in comparison with surface water treatment alone. Although results indicate that most large surface and groundwater drinking water resources are not likely to exceed safe drinking water standards due to the expansion of corn-starch based ethanol production, smaller water reservoirs in agricultural regions are susceptible to nitrate contamination in the future. Consequently, these sources might require energy-intensive drinking water treatment to reduce nitrate levels below 10 mg per liter of nitrate-nitrogen. Based on these results, I conclude that projected increases in nitrate contamination in water may impact the energy consumed in the water treatment sector, because of the convergence of several related trends: (1) increasing cornstarch-based ethanol production, (2) increasing nutrient loading in surface water and groundwater resources as a consequence of increased corn-based ethanol production, (3) additional drinking water sources that exceed the MCL for nitrate, and (4) potentially more stringent drinking water standards for nitrate. / text

The effect of cationic polymers on the rate of hydrolysis of cornstarch and cellulosic feedstocks was investigated. Poly(diallyldimethylammonium chloride) (p-DADMAC) and cationic polyacrylamides (c-PAMs) were used in the study. Experiments were performed to analyze the effect of both p-DADMAC and c-PAM on cornstarch liquefaction. Measurements were also made on the hydrolysis rates of bleached softwood to determine the mechanism through which cationic polymers accelerate cellulosic hydrolysis. Additional experiments were performed to study the effect of cationic polymers on different lignocellulosic feedstocks such as sludge, wheat straw and brown pulp. Studies on cornstarch hydrolysis showed that p-DADMAC increases the rate of α-amylase-induced cornstarch liquefaction, thereby reducing the enzyme dose necessary for optimal hydrolysis. Studies on bleached softwood showed that cationic polyelectrolytes increase the cellulase-induced hydrolysis rates of bleached wood fiber. It was shown that the polymer associates mainly with the amorphous region of fiber and acts principally on endoglucanase. Both c-PAM and p-DADMAC increased the glucose production of brown pulp at lower kappa numbers. Overall, cationic polymers enhanced the production of glucose from cornstarch and different cellulosic feedstocks. The polymer can reduce the enzyme dosage depending on the conditions and feedstocks used.

In the efforts to create sustainable production of heat and power and to reduce the net CO2 emissions to the atmosphere, alternative fuels are today being utilised. These fuels are, for example, biofuels and waste derived fuels such as different residues from the agricultural sector and the pulp and paper industry, municipal sewage sludge and municipal sorted solid waste. These fuels put new demands on the combustion facilities due to their chemical composition and this in turn calls for methods of prediction for the evaluation of their combustion behaviour. Most significant for the majority of these fuels are the high alkali and chlorine concentrations which cause bed agglomeration, deposit formation and corrosion on heat transfer surfaces. These problems can be solved if sufficient knowledge is obtained of the specific fuel or fuel mix. In this work, chemical fractionation, a step by step leaching method, was used on fuels, fuel mixes and fly ashes from co-combustion in a fluidised bed combustor. In addition, XRD and SEM-EDX were used for the fuel and fly ash characterisation. Different alkali chloride reducing additives i.e. kaolin, zeolites and sulphur were investigated as was the influence of various bed materials: silica sand, olivine sand and blast furnace slag (BFS). Some of the new, alternative fuels, such as municipal sewage sludge and meat and bone meal (MBM) contain high concentrations of phosphorus which is a very important nutrient essential in many biological processes. Phosphorus rock used as raw material in the phosphate industry is a depleting natural resource estimated to last for only 30-200 years according to different sources. The combustion of municipal sewage sludge enriches the phosphorus in the ashes while hazardous components such as pathogens and organic pollutants are rendered harmless after combustion. However, toxic heavy metals are also enriched in the ashes. One aim of the work was to find a sufficiently effective and low cost method for phosphorus extraction from fly ashes derived from municipal sewage sludge combustion. Two types of municipal sewage sludges were investigated using different chemicals for the phosphorus cleaning step in the waste water treatment plants. The first sewage sludge derived from a plant using iron sulphate as flocculant to precipitate phosphorus as iron phosphate. The second sludge meanwhile came from a plant using aluminium sulphate as flocculant to precipitate phosphorus as aluminium phosphate. Both sewage sludges were dewatered prior to combustion and co-combusted with wood pellets. At pH 1 nearly all the phosphorus was released from the fly ash derived from the sewage sludge where aluminium sulphate was used as a phosphorus precipitation agent. Iron sulphate as precipitant inhibited the phosphorus extraction from the ashes, resulting in only 50-80% of the phosphorus being released. Furthermore, the mobility of heavy metals to the leachates was investigated to establish whether the leachates were suitable as fertilisers. Only minor fractions of Pd, Hg, Cr, Cu, Mn, Co, Ni, As, Sb, V and Zn were found in the leachates, all well within the legislated limitations for fertilisers. However, one exception was Cd that was nearly totally dissolved in the leachate. Thus a decadmiation of the leachate is necessary prior to any utilisation of the ashes and reuse of phosphorus as fertiliser. / <p>Akademisk avhandling för avläggande av teknologie doktorsexamen vid Chalmers tekniska högskola försvaras vid offentlig disputation den 15 oktober 2008</p>

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.

This project aimed investigated cellulase in-situ production for large-scale on-farm production of lignocellulosic biofuel. Cellulase activity and glucose released by T. reesei with corn stover and wheat bran as co-substrates for solid state cultivation (SSC) were examined. Co-cultivation has previously increased T. reesei cellulase, but corn stover and wheat bran have not been co-cultivated (Dhillon, Oberoi et al. 2011). This work compared cellulase activity and glucose concentration of corn stover co-cultivated with 0-40% wheat bran in high solids. Samples with at least 20% wheat bran exhibited increased cellulase activity. However, the average glucose concentration without wheat bran was 3.29 g/L compared to 16.7 g/L with wheat bran. Glucose released by T. reesei on pretreated corn stover with 0-40% wheat bran was compared at the optimal temperatures for fungal growth and for cellulase activity after SSC. Previous research has rarely used cellulase from SSC to hydrolyze lignocellulose. Following SSC of T. reesei at 30°C for seven days, samples were warmed to 50°C for five days. Glucose concentration increased to 12.1 and 32.7 g/L for samples with and without wheat bran. This strategy could reduce lignocellulosic fuel production costs by eliminating need for commercial cellulase and is promising for efficient cellulose hydrolysis.

Doctor of Philosophy / Department of Biological & Agricultural Engineering / Donghai Wang / Sweet sorghum accumulates high concentrations of fermentable sugars in the stem, produces significant amount of starch in the grain (panicle) and has shown to be a promising energy feedstock. Sweet sorghum has a short growing season so adding it to the sugar cane system would be good. The overall goal of this dissertation is to enhance the attractiveness of biofuel production from sweet sorghum to fully utilize fermentable sugars in the juice, starch in the panicle and structural carbohydrates in the stalk for high efficiency and low-cost ethanol production. Sweet sorghum juice was incorporated into the dry-grind process which achieved 28% increase of ethanol yield compared to the conventional ethanol method and decreased enzymatic hydrolysis time by 30 minutes. A very high gravity fermentation technique was applied using sweet sorghum juice and sorghum grain yielded 20.25% (v/v) of ethanol and 96% fermentation efficiency. Response surface methodology was applied in order to optimize diffusion conditions and to explore effects of diffusion time, diffusion temperature, and ratio of sweet sorghum biomass to grain on starch-to-sugar efficiency and total sugar recovery from sweet sorghum. Starch hydrolysis efficiency and sugar recovery efficiency of 96 and 98.5% were achieved, respectively, at an optimized diffusion condition of 115 minutes, 95 °C, and 22% grain loading. Extraction kinetics based on the optimized diffusion parameters were developed to describe the mass transfer of sugars in sweet sorghum biomass during the diffusion process. Ethanol obtained from fermented extracted sugars treated with granular starch hydrolyzing enzyme and those with traditional enzymes were comparable (14.5 – 14.6% v/v). Ethanol efficiencies also ranged from 88.92 –92.02%.

Metabolic engineering of microorganisms for chemical production involves the coordination of regulatory, kinetic, and thermodynamic parameters within the context of the entire network, as well as the careful allocation of energetic and structural resources such as ATP, redox potential, and amino acids. The exponential progression of “omics” technologies over the past few decades has transformed our ability to understand these network interactions by generating enormous amounts of data about cell behavior. The great challenge of the new biological era is in processing, integrating, and rationally interpreting all of this information, leading to testable hypotheses. In silico metabolic reconstructions are versatile computational tools for integrating multiple levels of bioinformatics data, facilitating interpretation of that data, and making functional predictions related to the metabolic behavior of the cell. To explore the use of this modeling paradigm as a tool for enabling metabolic engineering in a poorly understood microorganism, an in silico constraint-based metabolic reconstruction for the anaerobic, cellulolytic bacterium Clostridium thermocellum was constructed based on available genome annotations, published phenotypic information, and specific biochemical assays. This dissertation describes the analysis and experimental validation of this model, the integration of transcriptomic data from an RNAseq experiment, and the use of the resulting model for generating novel strain designs for significantly improved production of ethanol from cellulosic biomass. The genome-scale metabolic reconstruction is shown to be a powerful framework for understanding and predicting various metabolic phenotypes, and contributions described here enhance the utility of these models for interpretation of experimental datasets for successful metabolic engineering.

Biomass is the world’s largest renewable energy source, accounting for approximately 10% of global primary energy supply, and 5% of energy consumed in the United States. Prominent national programs like the U.S. Renewable Fuel Standard incentivize increased use of biomass, primarily as a transportation fuel. There has been comparatively little government support for using biomass as a renewable feedstock for the chemical sector. Such asymmetry in incentives can lead to sub-optimal outcomes in the allocation of biomass toward different uses. Greenhouse gas reduction is among the most cited benefits of bioenergy and bio-based products, however, there is increasing controversy about whether increased use of biomass can actually contribute to greenhouse gas emission targets. If biomass is to play a role in current and future greenhouse gas mitigation efforts its use should be guided by efficient use of natural and economic resources. This thesis addresses these questions through a series of case studies, designed to highlight important tradeoffs in the use of biomass for greenhouse gas mitigation. Should biomass be used as a fuel, a chemical feedstock, or neither? The first case study in this thesis focuses on the ‘fuel vs feedstock’ question, examining the greenhouse gas implications of expanding the scope of the U.S. Renewable Fuel Standard to include credits for bioethylene, an important organic chemical readily produced from bioethanol. Results suggest that an expanded policy that includes bioethylene as an approved use for ethanol would provide added flexibility without compromising greenhouse gas targets – a clear win scenario. Having established that bioethylene based plastics can achieve similar greenhouse gas reductions to bioethanol used as fuel, this thesis expands the analysis by considering how the greenhouse gas emissions from a wider range of bio-based plastics compare to each of the main commodity thermoplastics produced in the U.S. The analysis demonstrates that there are large uncertainties involved in the life cycle greenhouse gas emissions from bio-based plastics, and that only a subset of pathways are likely to be preferable to conventional plastics. The following chapter then builds on the existing model to compare the greenhouse gas mitigation potential of bio-based plastics to the potential for reducing emissions by adopting low carbon energy for plastics production. That chapter concludes that switching to renewable energy across the supply chain for conventional plastics energy cuts greenhouse gas emissions by 50-75%, achieving a greater reduction, with less uncertainty and lower cost, than switching to corn-based biopolymers – the most likely near-term biopolymer option. In the long run, producing bio-based plastics from advanced feedstocks (e.g. switchgrass) and/or with renewable energy likely offers greater emission reductions. Finally, this thesis returns to the dominant form of policy surrounding biomass use: biofuel mandates. That study takes a consequential approach to the ‘fuel or neither’ question. Specifically, this work examines how petroleum refineries are likely to adjust their production in response to biofuel policies, and what this implies for the success of these policies. The research demonstrates that biofuel policies induce a shift toward greater diesel production at the expense of both gasoline and non-combustion petroleum products. This has the potential to result in an increase in greenhouse gas emissions, even before accounting for the emissions from producing the biofuels themselves.

Fossila drivmedel ger en negativ påverkan på miljö och klimat. Men frågan är om biodrivmedel är bättre. Det kan skilja stort mellan olika drivmedel beroende på vilken råvara och framställningsprocess som används. Syftet med studien är att göra en sammanställning av fördelar och nackdelar med olika fossilfria drivmedel som används och kan komma att användas i kollektivtrafiken i Gävleborgs län. I samråd med X-trafik, den regionala kollektivtrafikmyndigheten, har det framkommit att det främst är biodiesel (HVO - hydrogenerade vegetabiliska oljor), biogas och el som är intressanta att analysera. Rapporten kommer att redogöra hur användningen ser ut i andra delar av landet och i världen för att kunna anpassa kunskaperna till Gävleborgs län. I studien ingår även en granskning av produktionspotentialen för dessa drivmedel i länet. Det slutgiltiga resultatet av studien kommer att bidra till utvecklingen av en fossilfri fordonsflotta i regionen. Genom intervjuer med närproducenter av biogas (Gästrike Ekogas AB) och biodiesel (Colabitoil AB) samt med X-trafik inhämtades kunskap om hur produktionen ser ut i länet och vilka behov som finns. Detta tillsammans med en litteraturstudie gav resultatet. X-trafik har huvudansvaret för kollektivtrafiken och utför den genom entreprenörer som fått uppdragen genom upphandling. HVO har många fördelar mot andra dieselbränslen och kan tankas direkt i fordonen utan att dessa behöver modifieras. Dessutom görs den HVO som Colabitoil distribuerar och kommer börja producera på restavfall. En av X-trafiks entreprenörer har slutit ett avtal med Colabitoil vilket betyder att all fossil diesel som bussarna kör på idag kommer att bytas ut mot biodiesel. I Gävle stad kör bussarna på biogas och gasen produceras på avloppsreningsverket Duvbacken. Denna produktion täcker upp 60 % av behovet och resten är fossil gas. Med den nya anläggningen som Gästrike Ekogas håller på att bygga kommer behovet mer än väl täckas upp. Biogasen är även den gjord på restavfall. I den nya biogasanläggningen kommer de också få en utmärkt biogödsel fri från föroreningar, som kan KRAV-märkas och användas till odling för att ersätta konstgödsel. Elbussar är något som diskuteras av X-trafik och kan vara bra alternativ på vissa linjer dock är tekniken under utveckling fortfarande och investeringskostnaden är hög. Det finns potential att kollektivtrafiken i Gävleborgs län kan köra på 100 % miljövänligt, hållbara och närproducerade drivmedel inom en snar framtid. / The purpose of this study is to make a summary of the advantages and disadvantages of various non-fossil fuels that are used and can be used in public transport in the county. In consultation with X-trafik, it has emerged that it is mainly biodiesel (in the form of  HVO - hydrogenated vegetable oils), biogas and electricity that are interesting to analyse. The report will describe the use in other parts of the country and the world to adapt the knowledge to the county. The study also includes an investigation of the production potential of these fuels within the county. The final results of the study will contribute to the development of a fossil free fleet in the region. Through interviews with local producers of biogas (Gästrike Ekogas AB) and biodiesel (Colabitoil AB) and X-trafik information was collected about how the production is performed in the county and what the needs are. This, together with a literature review yielded the results. X-trafik has the main responsibility for the public transport and carries it out through contractors with assignments through procurement. HVO has many advantages compared to other diesel fuels and can be refueled directly in vehicles without modifications of these. Additionally, the HVO that Colabitoil distributes and will begin producing is made of residual waste. One of X-Trafik's contractors has signed a contract with Colabitoil which means that all fossil diesel the buses run on today will be replaced with biodiesel. In Gävle city the buses run on biogas and the gas is produced at the sewage treatment plant. This production covers 60% of the need and the rest is fossil gas. The new facility, which Gästrike Ekogas is building, will produce more than the public transport needs. Biogas is also made from residual waste. The new facility will also yield a by-product in the form of an excellent bio-fertilizer free of contaminants that can be KRAV labelled and used for cultivation to replace chemical fertilizers. Electric buses are something that is discussed, and may be a good option on certain routes, however, the technology is still under development and the investment cost is high. There is great potential that the public transport in the county can run on 100% eco-friendly, sustainable and locally produced fuels in the near future.

Parce que les ressources fossiles sont épuisables par définition, le carbone nécessaire à la production d'énergie et de matériaux pourrait provenir en grande partie de la biomasse lignocellulosique. Les procédés de fermentation sont capables de fournir une grande variété de produits d'intérêts capables de remplacer les synthons d'origine pétrolière. Cependant, en raison (i) de son caractère insoluble, (ii) de sa structure plus ou moins cristalline et (iii) de la nature des liaisons entre les maillons du polymère, la cellulose est un substrat carboné difficile à valoriser par voie biochimique/fermentaire seule. La pyrolyse rapide ou la liquéfaction de la cellulose sont principalement étudiées pour produire une bio-huile, qui serait valorisée par hydrotraitement catalytique en carburant ou en building blocks. Dans l'état de l'art actuel, les travaux à l'interface de ces deux domaines portant sur une conversion biochimique ou microbiologique de ces bio-huiles sont encore rares. L’objectif de cette thèse est de coupler un procédé de conversion thermochimique de la cellulose, pour la dépolymériser, à un procédé de transformation microbienne pour produire des solvants, des acides et des gaz (butanol, éthanol, acétone, acide acétique, acide butyrique, acide lactique, hydrogène) qui suscitent un fort intérêt dans l’industrie des carburants ou de la chimie verte. Pour ce faire, le bois de hêtre a été fractionné par les méthodes organosolv et chlorite/acide (SC/AA) afin de récupérer une pâte riche en cellulose. Des procédés de liquéfaction hydrothermale et de pyrolyse rapide ont été utilisés pour obtenir des sucres qui ont été finalement transformés par fermentation en synthons. De nombreuses méthodes analytiques ont été développées pour la caractérisation des produits issus de chaque étape du procédé. Enfin, un modèle du procédé utilisant le logiciel commercial Aspen Plus® a été développé pour établir les bilans de matière et énergie du procédé intégré : du fractionnement du bois, puis la liquéfaction de la fraction cellulosique et à la fermentation des bio-huiles / Because fossil resources are exhaustible by definition, the carbon needed for energy and materials production could be obtained from lignocellulosic biomass. Fermentation processes are able to provide a wide variety of interesting products that can replace the crude oil based "building blocks". However, the abundance of lignocellulosic biomass in the environment contrasts with its very low bioavailability. Indeed, because of (i) its insoluble nature, (ii) its more or less crystalline structure and (iii) the nature of the bonds between the polymer fibers, cellulose is a carbon substrate difficult to valorize by biochemical/fermentation processes alone. Fast pyrolysis or liquefaction of cellulose are mainly studied to produce a bio-oil, which would be upgraded by catalytic hydrotreatment into fuels or building blocks. In the current state of the art, studies at the interface of these two fields involving a biochemical or microbiological conversion of these bio-oils are still rare. The aim of this thesis is the coupling of a thermochemical conversion process of cellulose, to depolymerize it, to a microbial transformation process to produce solvents, acids and gases (butanol, ethanol, acetone, acetic acid, butyric acid, lactic acid, hydrogen) that are of great interest for the fuel or green chemistry industry. To do this, beech wood was fractionated by organosolv and chlorite / acid (SC / AA) methods in order to recover a cellulose-rich pulp. Hydrothermal liquefaction and fast pyrolysis processes were used to obtain sugars that were transformed into building blocks by fermentation. Many analytical methods have been developed for the characterization of products from each step of the process. Finally, a model of the process using the commercial software Aspen Plus® was developed to establish mass and energy balances of the integrated process including: the fractionation of the wood, then the liquefaction of the cellulosic fraction and the fermentation of bio-oils