Master of Science / Department of Grain Science and Industry / Yong Cheng Shi / In vitro digestibility of starch in sorghum grains differing in endosperm hardness and flour particle size was assayed by an Englyst resistant starch (RS) method. The starch digestibility increased as the particle size of flour decreased, but no significant difference in starch digestibility was observed among sorghum flours milled from grains with different hardness. To further understand the digestion of starch in sorghum, the effects of protein on starch digestion and amylose content in starch were determined. pH value was a factor affecting protein digestion since protein digestibility was higher at pH 2.0 than that at pH 1.3. Protein hydrolysis increased with time of pepsin treatment, leading to an increased starch digestion. RS content was 10.61-29.54% in native sorghum flours and 8.47-26.28% in isolated sorghum starch. The amounts of [Gamma]-kafirins extracted increased with time of pepsin treatment while [Alpha]- and [Beta]-kafirins decreased. The starch in sorghum flour with median hardness had a higher amylose content (23.9%) than the starch in hard and soft flours (~21%), which gave lower starch digestibility. Protein digestibility decreased after cooking while starch digestibility increased. Sulfhydryl groups decreased after cooking, indicating that disulfide bonds formed between protein molecules and may have formed a barrier for enzymes to access and digest starch. Confocal laser scanning microscopy (CLSM) showed that the protein matrix was less evident after pepsin treatment. As a result, starch digestion increased after protein matrix was removed.

Master of Agribusiness / Department of Agricultural Economics / Jeffery R. Williams / Anaerobic digestion is an alternative solution to organic waste management that offers economic and environmental benefits. The Kawangware open air market in Kenya generates approximately 10 metric tons of organic waste per day as a result of farm produce sold at the market. Fresh fruits and vegetables sold at the market account for more than 80 percent of the organic waste. This organic waste is left uncollected, piling up and therefore becoming pollution to the environment. Instead, this waste can be processed by anaerobic digestion to produce energy, organic fertilizer and greenhouse gas credits. The main objective of this project is to help investors and members of Kawangware Waste Utilization Initiative (a waste management community based organization in the Kawangware area) answer the following questions: (a) Is it economically profitable to invest in an anaerobic digestion system to convert the market organic waste to methane and fertilizer? (b) Is it economically profitable to burn the methane to generate electricity? To answer these questions, the study examines the costs and returns of producing methane, electricity, and fertilizer from organic waste under various scenarios using net present value, internal rate of return and payback period analysis techniques. Three production conditions under various scenarios using the anaerobic digester are examined. The conditions include: (a) Production of methane and organic fertilizer. (b) Production of methane, organic fertilizer, and carbon credits. (c) Production of electricity, organic fertilizer, and carbon credits. From these three production conditions examined, production of methane, organic fertilizer and carbon credits had the highest net present value of $332,610, internal rate of return of 21.4%, and the shortest payback period of 7.9 years. If carbon credits could not be sold the next best alternative would be production and selling of methane and organic fertilizer which has a net present value of $246,752, internal rate of return of 19%, and a payback period 9.2 years.

Ce mémoire porte sur la gestion des effluents organiques à l'aide d'un procédé intégré de valorisation énergétique dans le contexte d'une municipalité de 150 000 habitants en considérant la génération d'énergie et la réduction des gaz à effet de serre. Dans cette optique, la digestion anaérobie devient intéressante. Un premier scénario étudie la cogénération de chaleur et d'électricité à partir du biogaz issu de la digestion anaérobie des effluents organiques gérés par la municipalité : les résidus domestiques putrescibles et les boues d'usine municipale de traitement des eaux (scénario 1). Un second scénario propose d'ajouter le lisier issu des fermes régionales pour faire de la codigestion avec les matières gérées par la municipalité et faire de la cogénération de chaleur et d'électricité (scénario 2). Le troisième scénario propose de générer du gaz naturel renouvelable (GNR) en purifiant le biogaz pour accroître son pouvoir calorifique (scénario 3). Ces scénarios sont comparés d'un point de vue économique, énergétique et environnemental à l'aide du chiffrier MATTEUS version 5.11 développé par Hydro-Québec afin de proposer le meilleur procédé intégré de gestion à la municipalité en tenant compte des trois aspects. Le scénario 1 (cogénération) mène à une période de retour sur l'investissement (PRI) de 3,7 ans avec un prix d'achat de l'électricité de 0,10$/kWh. Le scénario 2 (codigestion) accroît la production de biogaz de 37%, mais augmente la PRI à 6,8 ans à moins que le digestat produit puisse être utilisé pour faire de la valorisation agronomique; cela devient économiquement avantageux. Le scénario 3 (GNR) n'obtient pas de PRI, car le coût d'achat du gaz naturel est trop faible. Par contre, ce scénario mène à la plus faible période de retour en énergie (3,3 ans) et réduit le plus les émissions de gaz à effet de serre (4261 tCO[indice inférieur 2] eq/an). Parmi les scénarios proposés, le scénario 1, cogénération des matières organiques gérées par la municipalité, représente l'alternative la plus intéressante économiquement et devrait être favorisé à l'heure actuelle. Toutefois, le scénario 3, GNR, se démarque dans les deux autres aspects.

Submitted in partial fulfillment of academic requirements for the degree of Masters of Technology: Department of Chemical Engineering, Durban University of Technology, 2009. / The primary objective of this project was to establish a screening protocol which could be used to access high strength/toxic effluent for toxicity and degradability prior to being disposed in wastewater treatment works. The serum bottle method (materials and method section) is simple, makes use of small glass vials (125 mℓ-volume were used in this research) which do not require any stirring nor feeding device or other engineered tool: a serum bottle is sealed immediately after all components are poured inside and thereafter conducted in a batch mode and occasionally shaken to ensure adequate homogenisation of the components. The only variables which are regularly measured are the volume of biogas produced and gas composition. The two assays, originally developed by Owen et al. (1979) to address the toxicity and the biodegradability have been combined in a single test called AAT, Anaerobic Activity Test, which enables one to assess simultaneously the inhibitory effect on the methanogenic biomass and the biodegradability of the test material as well as the ability of the biomass to adapt to the test material and therefore to overcome the initial inhibition. The screening protocol is illustrated in Annexure A. The protocol consists of a sequence of assays which employ the serum bottle methodology. A first step of the procedure is aimed at rapidly estimating whether the effluent is potentially toxic to the methanogenic biomass and in what concentration. The second step is a more extensive screening, aimed at precisely characterising the toxicity of the effluent, the extent of biodegradation that can be achieved, as well as at establishing whether a potential for adaptation of the biomass exists upon exposure. If the sample passes the screening stage, the same serum bottle method will be used to conduct a series of batch co-digestion experiments aimed at evaluating a convenient volumetric ratio between the test material and the readily biodegradable substrate. Finally, a laboratory-scale codigestion trial could simulate the full-scale process, thus enabling the selection of appropriate operating conditions for the start-up of the full-scale implementation. This the protocol has been used to assess the amenability to be anaerobically (co)digested of four industrial effluents, i.e. size and distillery effluents which are classified as high strength and scour and synthetic dye effluents classified as toxic. From the biodegradability and toxicity assays the following conclusions were drawn. The size and distillery effluent were found to be ii degradable at 32 g COD/ℓ and 16 g COD /ℓ concentrations respectively. Concentrations higher than these stipulated above were found inhibitory. Scour effluent was found to be recalcitrant at all concentration tested and synthetic dye was 100 % degradable at 0.12 g COD/ℓ and lower and highly inhibitory at concentration higher than 1.1 g COD/ℓ. Co-digestion experiment using serum bottle AAT method were undertaken between effluents i.e. size + distillery, size + scour, distillery + synthetic dye in an attempt to verify whether the digestion performance benefits from simultaneous presence of the two substrates. The volumetric ratios between the effluents were 1:1, 1:2, 2:1. The presence of two mixtures in the case of size and distillery had better methane production compared to individual substrate i.e. size or distillery separate. The mixture with volumetric flow rate ratio of 2:1 (size: distillery) was preferable in terms of process performance as it had highest COD removal compared to the other mixtures /ratios and individual substrates. The mixture of size and scour (2:1) had highest degradation percentage compared to other ratios but not high enough to qualify as degradable (less than 50 %). The mixture of distillery and synthetic dye had the same pattern with ratio of 2:1 giving the best COD conversion. The pattern than can be drawn from the degradability of mixtures is: the degradability of mixtures increase with the increasing amount of the most biodegradable compound/effluent in the mixture. Serum bottle results provided the detailed information regarding the safe operating parameters which should be used during the starting point for the larger scale investigation i.e. lab-scale investigations. The lab scale investigations were conducted primarily to validate screening and monitor how the digestion progresses and also to provide data for future project i.e. pilot plant investigation. Other effluents i.e. scour and synthetic dye and their co-digestion mixture were excluded from the lab-scale investigations since they were found to be non- biodegradable i.e. their COD conversion was less the 50 % in the screening protocol. Due to time constrains and other technical difficulties in the laboratory, the co-digestion of size and distillery mixture trials we not conducted on the laboratory scale. Laboratory-scale digestion trials showed that the best organic loading rate for distillery effluent in terms of reactor performance and stability was 1.0g COD/ℓ with efficiency of about 45 %, and for size was 2.0g COD/ℓ with an efficiency of 40 %. The efficiencies obtained in both effluents trials could be greatly improved by acclimation; however these results showed that the digestion of these effluents on the bigger scale is possible. / Water Research Commission

The production of pulp and paper is associated with the generation of large quantities of wastewater that has to be purified to avoid severe pollution of the environment. Wastewater purification in pulp and paper mills combines sedimentation, biological treatment, chemical precipitation, flotation and anaerobic treatment, and the specific combination of techniques is determined by the local conditions. Wastewater treatment generates large volumes of sludge that after dewatering can be incinerated and thus used for bio-energy production. Sludge is currently viewed as biofuel of poor quality due to its high water content, and some mills treat it solely as a disposal problem. Two strategies have been identified as feasible options to improve the energy efficiency of sludge management. One is drying using multi-effect evaporation followed by incineration. The other is anaerobic digestion of the wet sludge to produce methane. This thesis explores the energy balances of sludge management strategies in pulp and paper mills with special focus on anaerobic digestion. The first part consists of a system analysis, used to evaluate some wastewater treatment processes and sludge management, and the second part of empirical studies of anaerobic digestion of pulp and paper mill sludge. It was shown that the use of energy for aeration in aerobic biological treatment should be kept to the minimum required for acceptable quality of the processed water. Additional aeration for reduction of the generated sludge will only result in reduced energy generation in a subsequent methane generation stage. In the second part of the thesis, it is shown that anaerobic digestion is a feasible option for sludge management as it leads to production of high value biogas. Co-digestion with grass silage, cow/pig manure or municipal sewage sludge should then be used to counteract the low nitrogen content of pulp and paper mill sludge.

Surrogate organisms have been used to study highly pathogenic organisms, or organisms that cannot be cultured in the laboratory. Surrogates are selected based on multiple similarities to the pathogen, such as morphology, genome size and structure, and environmental characteristics. This dissertation utilized MS2 coliphage as a surrogate for norovirus and Ebola virus in three environments. MS2 is an icosahedral, single-stranded RNA bacteriophage. It is a male-specific coliphage that infects the bacteria Escherichia coli. Its properties, such as morphology and survival in the environment, have been likened to those of many enteric viruses. Because of this, it has been used as a surrogate for pathogenic enteric viruses for disinfection testing on surfaces, in water and in food; modeling the movement and survival of pathogens in different environments; and transfer properties from surfaces. This dissertation utilized MS2 as a surrogate in three different studies. In the first, MS2 is used as a surrogate for human enteric viruses in irrigation canals to predict the re-suspension of pathogenic viruses from bed sediment into overlying irrigation water using a flume to re-create field conditions in the laboratory. MS2 re-suspension into the overlying water was characterized at varying flow rates and velocities using two sediment types. Its overall re-suspension was not statistically significantly different (p > 0.05) between flow rates. The additional studies in this dissertation used MS2 as a surrogate for Ebola virus in human waste. Ebola virus is a BSL-4 organism that is spread through direct contact with bodily fluids. It is found in bodily fluids in concentrations between 10^5.5 and 10⁸ genome copies per milliliter. In the first study using MS2 as a surrogate for Ebola virus, efficacies of four disinfectants were tested using 10¹² PFU of MS2 in one liter containing 2.25% (w/v) organic matter at three contact times (1, 15 and 30 minutes). The purpose of this study was to assess the disinfectants on reducing virus in waste before toilet flushing. Peracetic acid and quaternary ammonium formulation were found to reduce the concentration of MS2 in the toilet bowl the fastest (within one minute) with the greatest reduction (2.26 and 1.99 log₁₀), when compared with the other disinfectants. Reductions observed from hydrogen peroxide were significantly less than those from peracetic acid and quaternary ammonium (p < 0.05). The contamination of restroom surfaces by MS2 was also evaluated after toilet flushing with and without disinfectant treatment. All four disinfectants were found to significantly reduce the viral concentrations on fomites after 15 minutes of contact (p < 0.05). Despite disinfectant use, three sites were contaminated in 100% of trials (N = 18). These were the toilet bowl rim, the toilet seat top and underside. The final study evaluated the inactivation of MS2 and several other viruses by thermophilic and mesophilic anaerobic digestion. Little information is available on the influence of the wastewater treatment process, specifically anaerobic digestion, on emerging viruses, such as Ebola virus. It is important to evaluate this process due to the environmental disposal and discharge of wastewater and solids into the environment. All viruses were recoverable after mesophilic digestion (reductions from 1.8-6.6 log₁₀ per mL), except the lipid-containing bacteriophage Φ6. Thermophilic digestion inactivated all viruses significantly (p = 0.0011) more than mesophilic digestion. The reductions by thermophilic digestion ranged from 2.8-7.1 log₁₀ per mL. The inactivation between the initial concentration and both digestion types was statistically significant (p = 0.007).

We initially studied the treatment of acid rock drainage using a sulfate-reducing bioreactor with zero-valent iron as the electron donor. The results demonstrate that this electron donor can serve as the sole exogenous slow-release electron donor to drive sulfate reduction over 400 operational days at short HRTs (1-3 days). The synthetic acid rock drainage contained high heavy metal concentrations (up to 50 mg/L of copper) and pH values ranging from 3.0 to 7.0. Treatment of this acid rock drainage efficiently removed Cu, Cd and Pb (>99.7%) and increased pH to circumneutral values (7.3-7.7). Elemental analysis indicated that formation of insoluble metal sulfides was responsible for the effective metal removal in the zero valent iron columns. In the second study, three inoculated columns containing anaerobic granular sludge were fed a synthetic medium containing H₂SO₄ and Cu²⁺ during the experimental period of 4 months. Algae biomass promoted 80% of sulfate removal (12.7 mg SO₄²⁻ d-1), enabling near complete Cu removal (>99.5 %), and alkalinity generation, raising the effluent pH to 6.5. In the algae amended columns Cu²⁺ was precipitated with biogenic H2S produced by sulfate reduction. Whole cell algae and lipid extracted algae biomasses were both shown to be effective e-donors in driving sulfate reduction of ARD, thus enabling the precipitation and removal of Cu²⁺. The precipitate retained in the columns was composed mostly of insoluble copper sulfide formed from the biogenic sulfide, as shown by sequential extraction and X-ray diffraction. In the third study, several pretreatments, i.e., thermal, chemical, sonication and combinations thereof, that enhance anaerobic biodegradability of Chlorella protothecoides biomass were evaluated. The results demonstrate that anaerobic digestion of pretreated Chlorella protothecoides biomass generates energy-rich methane and recovers nitrogen nutrients. Sonication of algal biomass under optimized conditions provided a significant increase in the methane yield (327 mL STP CH₄ g⁻¹ VS) compared to untreated algae (146 mL STP CH₄ g⁻¹ VS), as demonstrated in anaerobic digestion experiments incubated for 41 days. In contrast, thermal pretreatment provided only a moderate increase of the methane yield and alkaline treatment led to a decrease of the methane yield compared to the untreated algal biomass. Additionally, sonication treatment provided a 4.1-fold increase in the release of ammonia nitrogen during anaerobic digestion of the algal biomass. In the fourth study, the nutrient recovery and biogas generation from the anaerobic digestion of waste biomass from algal biofuel production was investigated. Anaerobic digestion of whole cell and lipid extracted Chlorella sorokiniana-1412 released 48.1 and 61.5% of the total algal nitrogen as NH₄⁺-N, and 87.7 and 93.6% of the total algal P as soluble P, respectively. The biochemical methane potential, quantified through the methane yield of whole cell algae and lipid extracted algae, was 0.298 and 0.253 L methane/g algal volatile solids, respectively. The conversion of lipid extracted algae and whole cell algae biomasses to methane was very similar (38 and 41% on a COD basis, respectively), indicating that the energy yield was not significantly lowered by extraction of the lipid fraction (which accounted for 9% of algal dry weight). Sonication improved the access of hydrolytic enzymes to algal biopolymers, compensating in part for the energy lost due to lipid extraction. The above results demonstrate that algal waste from the biodiesel industry has the potential to be recycled through anaerobic digestion into valuable nutrients and energy. These studies indicate that zero valent iron and algae biomass are promising reactive materials for the treatment of acid rock drainage in sulfate-reducing permeable reactive barrier systems. Additionally, to promote algae cultivation for the biodiesel industry, the anaerobic digestion of algae residues can generate nutrients and energy, making algae cultivation more fiscally attractive.

Thesis (MSc(Conservation Ecology and Entomology)--University of Stellenbosch, 2006. / The stomachs of 286 crocodiles (17 cm to 166 cm snout to vent length) were lavaged over a two year period. Crocodylus niloticus has a similar ontogenetic shift in diet to that of other crocodilians. Yearlings predated primarily on aquatic insecta and arachnida, as crocodile size increased (juveniles) the diet became more diverse including crustacea, amphibia and fish. The largest size class (sub-adults) consumed primarily fish. Yearlings fed consistently throughout the year, however a higher proportion of empty stomachs occurred within the juvenile and sub-adult size classes during the winter months. A captive experiment with wild caught crocodiles (0.7 kg - 20 kg) indicated a decrease in satiation rate (maximum mass of food eaten as a percentage of crocodile body mass) from 11.3 % to 6.5 % with an increase in crocodile size. Wild yearlings consumed 0.48 % of their body mass in prey per day, and juveniles, 0.23 %. The wild food conversion rates of natural prey were low, 32 % and 40 % for yearlings and juveniles respectively. This was possibly due to a high percentage of indigestible (chitinous) invertebrate mass in the diet. The percentage of stomach stone mass to crocodile body mass increased with crocodile size. Seven species of nematodes were found within the stomachs, four of which represent new geographic records.

<p>All products will eventually end up as waste, which in a sustainable society has to be handled in an efficient and environment friendly way. This report focuses on waste fractions meant for combustion, often difficult to characterize. However, more homogeneous fractions that are treated biologically are also discussed.</p><p>The study concerns the region of Borås, Sweden, where the waste plant Sobacken has provided a good starting point. On this site, fuel to the Energy-from-Waste plant of Borås Energi is prepared and the biological waste is treated through anaerobic digestion.</p><p>One important part of the study has been to collect experience-based knowledge from the technical staff at Sobacken and Borås Energi. This information was compiled into an overview of wanted and unwanted fractions to the preparation plant and the boilers respectively. The purpose of this overview is to complement existing delivery terms and thereby facilitate an increased quality of the fuel from the suppliers.</p><p>A significant element of the analysis has been to characterize the content of the industrial waste sent to Sobacken for combustion. Chemical analyses of the prepared fuel as well as the conducted waste component analysis indicate a heterogeneous composition of the waste. A heterogeneous fuel often results in an uneven combustion, leading to higher emissions and an unwanted variation in the energy production.</p><p>Through the waste component analysis, a comprehensive picture of the waste composition was attained. Materials non-valid for delivery mostly consisted of wet domestic waste (biodegradable materials), but some hazardous waste was also found. The results of the waste component analysis were communicated to the involved suppliers and this has already resulted in a considerable reduction of the amount of biodegradable waste in the deliveries of industrial waste.</p> / <p>Förr eller senare blir alla produkter avfall, som i ett uthålligt samhälle måste hanteras på ett resurssnålt och miljövänligt sätt. Det här arbetet är främst inriktat mot de svåridentifierade fraktionerna som är ämnade för förbränning, men berör även de mer homogena fraktionerna som behandlas biologiskt genom rötning.</p><p>Arbetet har utförts i Boråsregionen där Sobackens avfallsanläggning, med beredning av avfallsbränsle till Borås Energis två FB-pannor och rötkammare, har utgjort en naturlig utgångspunkt.</p><p>Ett stort inslag i arbetet var sammanställning av erfarenhetsbaserade kunskaper hos driftteknikerna på beredningsanläggningen, liksom hos Anders Johnsson på Borås Energi. På detta sätt erhölls viktig information om både bra och dåliga fraktioner, för såväl avfallskross som för pannor. Dessa fakta har bland annat använts för att sätta samman en översikt över önskade respektive oönskade fraktioner. Översikten är tänkt som komplement till befintliga leveransregler, i syfte att förenkla för avfallsleverantörerna.</p><p>Stor vikt har lagts vid att försöka kartlägga sammansättningen av det verksamhetsavfall som kommer in till Sobackens beredningsanläggning. Både kemiska analyser av bränsleprov och utförd plockanalys visar på en heterogen sammansättning i avfallet. Ett heterogent bränsle brinner i många fall ojämt, vilket resulterar i högre emissionsnivåer samt en icke-önskvärd variation i energiproduktion.</p><p>I och med plockanalysen erhölls en övergripande bild av förbränningsavfallets sammansättning. Det icke leveransgilla materialet som påträffades utgjordes främst av blött hushållsavfall (biologiskt nedbrytbart material), men även av en del elektronik påträffades. Efter avslutad analys kommunicerades erhållna resultat med aktuella leverantörer, vilket hittills har resulterat i en betydande minskning av biologiskt nedbrytbart material i verksamhetsavfallet.</p>

The rocky intertidal zone, experiencing fully marine and fully terrestrial conditions, has become increasingly investigated as a model ecosystem for studying the future implications of climate change. The barnacle, Balanus glandula, a common rocky intertidal inhabitant, plays an important role as a key prey item for many organisms. Low tide can be particularly challenging for barnacles as they are marine organisms subjected to the abiotic conditions of a terrestrial environment. The most stressful of these are increased temperature and decreased oxygen availability. This study aimed to investigate how low tide impacts the energy budget, specifically the digestion, of B. glandula. Barnacles are unable to feed at low tide however, if they were able to digest at low tide, they could maximize their energy intake by emptying their stomach to prepare to feed at the next high tide. However, digestion is a metabolically costly activity, which could make it less energetically favorable to digest when there’s less oxygen available. To test for an effect of low tide on digestion, barnacles were fed, and the time to first fecal production measured as a ‘baseline’. This was repeated, but barnacles were exposed to either a 16ºC or 35 ºC low tide immediately after being fed. The change in digestion time was calculated by comparing these two times for each barnacle. It was found that regardless of temperature, barnacles delayed their digestion by about 50-60 minutes after exposure to a one hour low tide. To determine the energetic cost of digestion, the rate of oxygen consumption was compared between starved and digesting barnacles. I was unable to detect any evidence of elevated metabolic activity during digestion. Additional testing is needed to confirm these results as the barnacles may have not fed during the trial, thus had no food to digest. While it appears that increasing temperatures associated with climate change will have little impact on the digestion of barnacles at low tide, if climate change alters the duration of low tide, there could be an energetic impact to barnacles due to the slowing of their metabolism as indicated by the delay in their digestion.