No description available.

This thesis investigates an application of immobilized lipase for pre-treating wastewater containing fats and oils, which is difficult to treat practically. The kinetics of soluble lipase was studied for establishing background of the lipase. The immobilization of lipase was adopted in order to repeatedly use the expensive lipase. The developed immobilization methods were based on the characteristics of carriers, but covalent bonding of lipase was preferred because of strong adsorption nature. Three types of materials, nylon membrane and polystyrene-divinylbenzene and silica gel beads, were used for studying the lipase immobilization characteristics. The lipase from Canada rugosa was chosen because of its relatively high catalytic activity and commercial availability. The oily wastewater sources used were a simulated mixture of olive oil and distilled water as well as actual restaurant oily wastewater. A packed bed reactor packed with immobilized lipase was suitable for the study. Moreover, a comparative study of anaerobic digestion of lipase treated and un-treated oily wastewater was undertaken to evaluate the efficiency of the lipase pre-treatment method due to lack of the relevant literature in the enzymatic wastewater treatment field. The kinetics of lipase catalyzed hydrolysis reactions was investigated in a stirred tank reactor. The experimental results confirmed that the lipase catalyzed reaction obeyed Michaelis-Menten model. The optimal pH and temperature of the lipase catalysed hydrolysis reaction were 7 and 37°C, respectively. The conversion of oil to fatty acid was dependent on the reaction time and mass of the enzyme used. The lipase activities depended on the concentrations of some selected additives. Calcium ion improved lipase activity significantly amongst the additives used. / The immobilization of lipase was carried out using different materials, nylon membranes, polystyrene-divinylbenzene beads, and silica gel. Covalent adsorption was simple and successful for immobilizing the lipase onto nylon membrane which was pre-treated with HC1 solution for releasing amino groups. The adsorption of lipase was completed after only a 2-hour reaction time. It was much more practical for this shorter adsorption time (2 hours) rather than the 24 hours required for physical capillary adsorption of lipase. The properties of the immobilized lipase and the performance of the reactors we compared amongst the soluble and immobilized lipase forms. The immobilization, particularly for covalent bonding, made lipase more resistant to thermal deactivation. It was evident that the optimum temperature was shifted from 37°C for the soluble lipase to 45 and 40°C for immobilized lipase adsorbed onto nylon and polystyrene-divinylbenzene beads, respectively. The immobilized lipase could be used repeatedly with only little activity loss. The repeatedly operational stability made the reuse of the immobilized lipase possible. Comparison was also made between two types of beads, polystyrene-divinylbenzene beads and silica gels. Though polystyrene-divinylbenzene beads showed higher lipase activity and shorter adsorption time when compared to silica gels, the forme beads were not suggested for large scale study because of high cost of the beads. On improvement achieved in this work was that the 24 hours required for silanization of silica gel was reduced to only a few hours using evaporating 3-APTES in acetone instead of refluxing 3-APTES in toluene. / It is worthwhile to point out that much higher enzyme activity was obtained using the packed bed reactor as against the membrane reactor when aqueous oil emulsion was fed into the reactors. The lipase activity was 64.2% of soluble lipase activity for the immobilized lipase in the packed reactor but its activity was hardly detectable in the membrane reactor. Moreover, the operation of the packed bed reactor solved the of separating problem that severely hampered the lipase catalytic activity in the membrane reactor in aqueous phase. This result suggests that the packed bed reacts with the immobilized lipase is applicable in treating oily wastewater. The intrinsic parameters, Vmax and Km, were evaluated to study the internal diffusional effects of the porous spherical silica gel on the immobilized lipase. The changes of Vmax and Km for the immobilized lipase from those of the soluble lipase indicated that some alteration in the lipase intrinsic properties was caused by the immobilization of lipase. However, the magnitude of Thiele modulus suggested the immobilized lipase was most likely reaction controlling. In addition, good agreement for Vmax and Km from experiments and numerical model estimations seemed to suggest that the numerical model could be used for estimating Vmax and Km for the immobilized lipase. / An application was tried for conducting the hydrolysis of oily restaurant wastewater by soluble and the immobilized lipase. Enzyme activity of both forms was severely inhibited by the oily wastewater. The enzymatic activity was only 20% and 15% for soluble and the immobilized lipase, respectively, when compared to the initial activity value for the hydrolysis of olive oil by soluble lipase. Evaluation of the efficiency for the proposed lipase pre-treatment method was carried out by monitoring the performance of two anaerobic digesters. These two digesters were fed with lipase treated and untreated restaurant wastewater that was neutralised with KOH solution prior to feeding. The oil-floating problem was minimised by this saponification of fatty acids with potassium hydroxide. However, there was no clear sign of an improvement for the treatment efficiency of the anaerobic digesters in terms of COD removal and methane production rate resulted in digesting lipase treated oily wastewater when compared to the one without lipase pre-treatment.

Increasing demands for improved water quality in receiving waters, effluent reclamation and reuse have prompted wide interest in the use of wetlands for the treatment of wastewater. Over a four year period, domestic sewage effluent was treated using a range of gravel based, subsurface flow constructed wetland systems. Weekly samples at inlet and outlet points were assayed for suspended solids, biological oxygen demand, organic carbon, total kjeldahl nitrogen, ammonium, nitrate/nitrite, phosphorus, dissolved oxygen, temperature, pH and faecal coliform levels. The wetland system received secondary treated effluent for three years and primary settled effluent for one year. The potential of constructed wetland systems for nitrogen removal and potential pathogen reduction was investigated. Nitrogen removal was characterised by estimation of potential nitrification and denitrification rates within the system. Disinfection performance of the wetland system was assessed by enumeration of faecal indicator bacteria in the system influent and effluent, as well as with distance along the length of the system. The removal rate was estimated, considering influent and effluent faecal coliform concentrations as well as system hydraulic retention time and temperature. / Master of Science (Hons)

none

published_or_final_version / Public Health / Master / Master of Public Health

abstract / Microbiology / Master / Master of Philosophy

Consumer health information technologies (CHITs) are emerging as promising tools for delivering healthcare services and facilitating patient self-management of chronic diseases; however, the use of the CHITs is largely constrained by usability problems and unclear evidence on the effectiveness of the technologies. The ergonomics research team of The University of Hong Kong developed a patient-centered computerized self-monitoring system that appeared to be useful and easy to use; with the system, this thesis focuses on the examination of the short-term impacts of the technology on patient outcomes for diabetic and hypertensive patients. The self-monitoring technology was designed using user-centered approaches and relevant human factors principles. Iterative usability evaluations were conducted to assess and improve the usability of the technology with 97 chronically ill patients. Also, using data from a larger randomized controlled trial (RCT) of technology-based disease self-management to improve patients’ outcomes, this thesis compared the short-term effects of the use of a computerized self-monitoring system to usual care using 63 patients with type 2 diabetes and hypertension for four weeks. Thirty-three patients were randomized into intervention group, whose disease care was supported by the self-monitoring system, while 30 patients into control group, who continued with their usual care. A pretest-posttest repeated measures design was employed to determine the effects of the technology on clinical, psychosocial, behavioral, usage, and technology perception outcomes over time. Measurements were obtained at baseline, and after 2 and 4 weeks. The iterative usability studies improved and verified the usability of the self-monitoring system for chronically ill patients. Results from the RCT showed that after four weeks, there were significant decreases in systolic blood pressure (p < 0.001) and diastolic blood pressure (p < 0.001), self-efficacy for managing chronic disease (p = 0.001), and adherence to treatment (p = 0.001) in the intervention group compared with the control group. Significant differences in favor of intervention group after four weeks were also documented for changes of several quality of life subscales (i.e., general health (p = 0.010), role physical (p = 0.001), role emotional (p = 0.002), bodily pain (p = 0.050), and physical component summary score (p = 0.005)), and perceived ease of use (p = 0.007). No significant difference was found between groups for fasting blood glucose (p = 0.687), perceived usefulness (p = 0.661), frequency of self-monitoring of blood pressure (p = 0.230) and self-monitoring of blood glucose (p = 0.993), and several other quality of life subscales over time. The usability evaluation presented in this thesis report demonstrated that the method was effective and efficient in identifying potential usability problems at the early stage of system development for CHITs. The findings from the RCT indicated that the use of the human factored-engineered self-monitoring technology had short-term effectiveness in improving blood pressure control, self-efficacy for managing chronic disease, adherence to treatment, and quality of life for patients with type 2 diabetes and hypertension. A human factored-engineered self-management technology appears to be an effective tool in patient self-management of chronic diseases. / published_or_final_version / Industrial and Manufacturing Systems Engineering / Doctoral / Doctor of Philosophy

No description available.

No description available.

No description available.