Anaerobic digestion (AD), as one of the oldest human biotechnology, has attracted revived research focus on the underpinning biological principle in recent years due to its potential in renewable green energy. With the assistance of the latest 454 deep sequencing technology, two independent studies were conducted with a shared goal to understand the operational influences on the AD microbiology from the unprecedented depth and breadth of genetic information. The first study aimed to decipher the contribution of a newly-devised waste sludge pretreatment method, which promised significant improvement in downstream biogas production. The first application of whole genome metagenomic approach on this topic revealed extensive shifts in both microbial and functional consortia towards higher biodegradation after pretreatment; meanwhile dominant acetoclastic and hydrogenotrophic methanogenesis pathways were identified concurrently with an alternative enzymology in Methanosaeta. The second study focused on the temporal dynamics of bacteria residing in production-scale biogas bioreactor coupled with multiple-sampling strategy for a realistic description of the actual microbial structure. Both bacterial fingerprint marked by feedstock and evolutionary drive towards biodegradation were revealed by 16S rDNA amplicon multiplex pyrosequencing, where clustering analyses further delineated the taxonomic plasticity and functional resilience of the bacterial communities over time. Phylogeny coverage of the highly diverse population was also improved by the adopted strategy, providing insights for sampling and sequencing standards. Altogether, the combined results garnered knowledge enrichment to the relationship between AD microbiology and operational parameters, which will assist the design of more efficient bioenergy platform in future. / published_or_final_version / Biological Sciences / Master / Master of Philosophy

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.

The purpose of this study was to determine the validity and reliability of an 8-flight tower climb test (TCT) to assess anaerobic performance in urban firefighters. Twenty-five professional urban firefighters participated in the validity testing of the TCT versus the Wingate Anaerobic Test (WAT) over 2 randomly sequenced testing sessions. Test-retest reliability was assessed separately in 21 active male and female participants over 2 TCT trials. During both validity and reliability testing for the TCT, participants ascended a firefighting training tower as fast as possible from a 1.7m running start while wearing firefighter protective equipment. Time was measured and power was calculated from the foot of the training tower to the top of the first (height = 1.75m) and eighth (height = 13.89m) flights of stairs. During the other session assessing TCT validity, participants completed a 30-second WAT using a resistance of 85gkg-1 body weight (BW). Several significant correlations were found including those between TCT power and: 1) mean WAT power generated for the duration equivalent to TCT time (r = 0.869), 2) peak power for the first 2 seconds of the WAT (r = 0.868), and 3) WAT peak power (r = 0.864). TCT test-retest performance in 21 active males and females showed that the test is highly reproducible. The mean time of completion of the 8-flight TCT was 21.81 + 5.03 seconds and 21.38 + 4.86 seconds for Trials 1 and 2, respectively. Intraclass correlations for time and power data from the first and eighth flights ranged from 0.94 to 0.99, and coefficients of variance ranged from 2.0% to 7.5%. These findings provide strong evidence that the TCT is a valid and reliable field-based assessment of occupation-specific anaerobic performance in urban firefighters. / Graduate

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.

The Continuously fed Stirred Tank Reactor (CSTR) is a popular design for anaerobic treatment of wastewater. This reactor type is simple in design and operation, independent of biomass type and low in capital costs. The CSTR has, however, to be operated at long Hydraulic Retention Times (HRT) of the order of 16 to 30 days since biomass is continuously lost with the effluent. Various alternate concepts of reactor design have, therefore, been developed to allow more rapid treatment. Treatment can be enhanced by retaining biomass within the digester so that the HRT is decoupled from solid biomass retention time (SRT). Unlike in continuous stirred tank digesters where the SRT is equal to HRT, the SRT in other designs are much greater than the HRT. This allows the wastewater to be treated at high throughputs while retaining the biocatalyst (or biomass) mediating the treatment within the digester. In this study the operation of a CSTR was intensified by separating SRT from HRT while taking into account the economical aspects. The intensification of operation is defined as increasing wastewater throughput or organic loading rate while at the same time maintaining efficiency of treatment and robustness to reject disturbances (changes in wastewater concentration and flow rate). The operation of existing CSTR was intensified by addition of carriers. It is hypothesized that by providing surfaces (or carriers) for bacterial attachment within the continuous stirred tank digester, biomass will be better retained and the wastewater throughput can be increased. The carriers or surfaces employed in this study were light carrier elements (shredded granular rubber tire having a density of 0.96 g/cm3) that move gently with the water in the reactor. This carrier material is much cheaper compared with other commercial carrier materials. This reactor type, called an Anaerobic Moving Bed Reactor (AMBR), was applied in this study to treat high strength synthetic wastewater, containing molasses as the main substrate. The improvement of reactor performance was clearly shown by the capability of the system to be operated without any difficulties at HRT of 6 days at an OLR of 5.8 g COD/l/d or at HRT of 1 day at an OLR of 4 g COD/l/d. The carriers were shown to be effective in retaining biomass aggregates. The AMBR was further intensified by changing the feeding strategy. It was shown that in stirred tank digester without carriers an intermittent feeding strategy resulted in better microbial capacity to degrade higher chain volatile fatty acids like propionic and butyric acids than the continuous feeding mode. An increase in degrading capacity of the intermittently fed digester was shown via degradation rates of pulse additions of propionic and butyric acids and by its capability of handling all changes in loading rates imposed. The continuously fed digester, receiving constant feed, on the other hand, suffered more when loading rates were changed, and the degradation rates of propionic and butyric acids were slower. The intermittent feeding mode was then implemented on the AMBR, and it was operated as a sequencing batch reactor with a fill, react, settle and decant period in each cycle. The sequencing batch mode when applied to the AMBR (now called an Anaerobic Moving Bed Sequencing Batch Reactor or AMBSBR) could increase capability of the digester to handle higher shock loads. At 3.8 d HRT the AMBSBR could handle an OLR of 10.8 g COD/l/d as opposed to 7.4 g COD/l/d by the AMBR. At 2.5 d HRT the AMBSBR could handle an OLR of 6.4 g COD/l/d while the AMBR could only be loaded at an OLR of 4.2 g COD/l/d. The ratio of SRT to HRT was at least 15 for this reactor. The reactor was able to handle concentrated feed flow rates at longer cycles or more dilute feed flow rates at frequent shorter cycles. The proposed operational strategies were verified by using a structured mathematical model which was developed based on the IWA ADM1 model. Several modifications were implemented to the model to obtain better predictions. The modified model was capable in predicting all the trends of the operating variables from both continuously and intermittently fed reactors. None of the two model versions (ADM1 and modified models) was, however, able to predict the increased propionate degradation capacity in intermittently fed digesters. The reason for this was the assumption of fixed stoichiometry of fermentative reactions for glucose mineralisation. By modifying the fractions of glucose mineralisation a better fit between experimental results and the model could be obtained.

Thesis (Ph.D.)--Ohio University, November, 2007. / Title from PDF t.p. Includes bibliographical references.

Thesis (M. E.)--University of Canterbury, 2008. / Typescript (photocopy). "January 2008." Includes bibliographical references (leaves 50-56). Also available via the World Wide Web.

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

Thesis (doctoral)--Karolinska Institutet, Stockholm, 1995. / Added t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (doctoral)--Karolinska Institutet, Stockholm, 1995. / Added t.p. with thesis statement inserted. Includes bibliographical references.