Thesis--University of Helsinki, 1999. / Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1932. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf [29]).

Thesis (Ph.D.) - University of Queensland, 2006. / Includes bibliography.

Northern peatlands occupy a very small proportion of the Earth’s surface but contain nearly a third of the world’s soil organic carbon. These wetland systems produce substantial fluxes of CH4, a potent greenhouse gas, and are expected to experience particularly high annual mean temperature increases as global climate change proceeds, which could result in a significant positive feedback. Using radioisotope labeling, we quantified the rates of two pathways of CH4 production in six sites in northern Michigan along a physiochemical and ecological gradient that characterizes northern peatlands. We found that the rates of these two pathways displayed markedly different dynamics in space and time and that the hydrogenotrophic pathway, previously presumed to be less significant in these systems, can increase substantially and become dominant across the landscape when water tables are high. Quantifying these two pathways provides critical insight into understanding dynamics of CH4 production in northern peatlands.

Anaerobic digestion is a useful method for stabilizing and reducing the waste activated sludges (WAS) produced from biological secondary treatment. Pretreatments can make anaerobic digestion more efficient. However, the study of anaerobic digestion and pretreatments is limited to a focus in treating conventional WAS. Therefore, WAS from three non-conventional municipal wastewater treatment systems, a rotating biological contactor (RBC), a lagoon, and a moving bed bioreactor (MBBR), were digested anaerobically to determine the sludges’ biogas potentials compared to a conventional WAS. All three WAS had lower biogas potential normalized per volatile solids than conventional sludge by 46% + 6 (MBBR), 63% + 6 (RBC), and 77% + 7 (lagoon). The four sludges were pretreated with ultrasonic energies of 800 - 6550 kJ/kg TS to illustrate impact of sludge type on biogas production, solubilization, and digestion kinetics. All four sludge types responded uniquely to the same levels of sonication energies. The greatest increase in biogas production over the control of pretreated sludge did not coincide consistently with greater sonication energy but occurred within a solubilization range of 2.9 – 7.4% degree of disintegration (DD) and are as follows: 5% + 3 biogas increase for conventional sludge, 12% + 9 for lagoon, 15% + 2 for MBBR and 20% + 2 for RBC. The yield of biogas production related to soluble COD decreases with increased sonication energy. Hence it is likely that sonication produces refractory COD or causes inhibition in biogas production. The effect of sonication on digestion kinetics was inconclusive with the application of Modified Gompertz, Reaction Curve, and First Order models to biogas production. Diauxic growth patterns of biogas production of sonicated conventional waste demonstrates that the active time of digestion can be decreased through the conversion of less preferential substrates into existing, preferential substrates.

Juvenile idiopathic arthritis (JIA) is a common chronic disease of childhood. Children with JIA have lower peak oxygen consumption (V0₂ peak) than healthy children. In order to examine the cardiorespiratory response during aerobic exercise and the anaerobic to aerobic ratio (metabolic index), maximal exercise tests were performed in JIA subjects and age- and sex-matched controls (CON). Thirteen children aged 10 to 17 years with JIA and 9 CON participated. Peak powe r(watts, W) and total work (Joules, j) were determined with the Wingate anaerobic cycling test. VO₂ peak was measured by a maximal staged exercise test on a cycle ergometer. Cardiac output (CO, liters/minute) was measured with Doppler echocardiography. Arterial — mixed venous oxygen index (A-V0₂) and systemic vascular resistance (SVR) were calculated. Patient questionnaires included habitual activity, visual analog scale for joint pain and the childhood health assessment questionnaire. Physician completed data included active joint count and articular severity index. Compared to CON and reference age-matched norms, JIA subjects had lower aerobic fitness. VO₂ peak in JIA was 31.3 ml/min/kg (20.2-49.9), Z score -1.4 (-.06--2.4) and in CON was 47.9 ml/min/kg (32.7-54.1), Z score of -0.17 (-1.6-.87). [p = 0.013 V0₂ peak, p=0.011 Z score]. There were no significant differences in CO, A-V0₂ or SVR buttrends towards lower CO and higher SVR in JIA subjects were observed. During anaerobic exercise JIA subjects completed less total work (168.5 j/kg (107-252) JIA, 224 j/kg (180-248) CON, p=.036) but had similar peak power (9.7 W/kg (5.6-13.7) JIA, 11.3 W/kg (9.8-14.5) CON, p=.095). The metabolic index did not differ between JIA and CON. There was no significant correlation between disease activity, function and fitness measures in JIA subjects. Children with JIA have moderate impairments in aerobic fitness. CO and A-V0₂ during aerobic exercise did not significantly differ between JIA subjects and CON. Anaerobic fitness was mildly impaired with less total work completed by JIA subjects. Further research with larger numbers is required to determine factors contributing to limited fitness in JIA. / Education, Faculty of / Kinesiology, School of / Graduate

M.Tech. (Medical Technology) / Please refer to full text to view abstract

Metabolic and biogeochemical processes in hyporheic zones may depend on inputs of coarse particulate organic matter. Our research focused on how differing quantity and quality of organic matter affects metabolism and nutrient retention in the hyporheic zone of a low-order Appalachian stream. We hypothesized that hyporheic metabolic rates should increase with organic matter additions because the biotic activity is limited by organic matter availability. Four sets (n=4 amendments/set) of plots were established on a tributary of Hugh White Creek, NC. Sediment was extracted and was either supplemented with leaves, wood, or plastic strips, or sediments remained unamended sediments. Following augmentation sediments were reimbedded and approximately three months later sediment was removed from each plot. Aerobic and anaerobic metabolism were measured as the change in O2, and CO2 in recirculating microcosms. At the same time, we monitored other possible terminal electron accepting processes and changes in nutrients. Aerobic metabolism was low in all treatments and respiratory quotients calculated for all treatments indicated that metabolism was dominated by anaerobic processes. Anaerobic and total (combined aerobic and anaerobic) respiration rates were significantly greater (P < 0.05) in plots treated with leaf organic matter compared to controls. Nutrient retention (NO3-N, NH4-N, and DOC) was enhanced in augmented treatments. Measured losses of dissolved organic carbon accounted for 50% total carbon liberated by respiration in amended sediments, whereas in unamended sediments loss of DOC represented only 7% of measured respiration. Augmentation with greater quality organic matter stimulated respiration in hyporheic sediments. Anaerobic processes dominated metabolic rates in both control and amended sediments. Enhanced metabolic rates increased retention of many solutes indicating that energy flow and nutrient dynamics in the subsurface of streams may depend upon the quantity and quality of imported carbon. / Master of Science

Sequencing batch reactor (SBR) systems were used for the development of a system and operating procedures for the high production of polyhydroxyalkanoates (PHAs) by wastewater treatment (activated sludge) bacterial cultures. It was found that unbalanced growth conditions stimulated massive PHA production in activated sludge biomass. Operating conditions had a significant effect on PHA production and the composition of the accumulated copolymer when either laboratory prepared mixtures of organics or a high acetic acid industrial wastewater were used as the organic substrate mixture. Fully aerobic (AE) conditions with nitrogen (N) and phosphorus (P) limitations were the optimum conditions for PHA production when the laboratory prepared mixtures of orgnics were used, while fully AE with the combinations of N, P, and potassium (K) limitations were better for PHA production using a high acetic acid industrial wastewater as the substrate. One nutrient limitation or partial limitation of either N or P as used for commercial production using pure cultures did not promote massive PHA production in activated sludge biomass compared to the combination of nutrient limitations. A maximum cellular PHA accumulation of 70%TSS was obtained under fully AE conditions with multiple alternating periods of growth and N&P limitations. Microaerophilic/aerobic (MAA/AE) or anaerobic/aerobic (AN/AE) cycling promoted less PHA production compared to fully AE conditions. The relative amounts of the PHA copolymers formed, i.e., polyhydroxybutyrate (PHB) and polyhydroxyvalerate (PHV) were different under different operating conditions, even though the types and amounts of volatile fatty acids (VFAs) in the feed were the same. It was determined that high total phosphorus (TP) content inside the bacterial cells had a significant detrimental impact on PHA production by activated sludge biomass. A two-stage bioprocess was a better approach for obtaining activated sludge PHA accumulation because a growth phase was necessary to grow the bacterial population that contains minimal TP before starting the subsequent PHA accumulation phase. Seeding sludge obtained from a conventional fully aerobic wastewater treatment system was more suitable than seed obtained from a biological phosphorus removal (BPR) system because bacterial populations from BPR systems tended to convert organic substrates to intracellular carbohydrate content rather than PHA under nutrient limitation conditions. The molecular weights and melting point temperatures of PHAs produced by the mixed culture of activated sludge biomass were comparable to those obtained from pure cultures and have the potential to be used for commercial applications. The results of this study indicate that activated sludge biomass has considerable potential for PHA production for commercial purposes, and likely could do so utilizing wastewater sources of organics. In particular organic rich, nutrient limited wastewaters have potential for efficient PHA production. / Ph. D.

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