고도산화공정 수처리 살균 시스템의 성능 평가 기법 개발
- 고도산화공정 수처리 살균 시스템의 성능 평가 기법 개발
- Other Titles
- Performance Evaluation of Water Treatment Processes (AOP + UV Disinfection) for the Production of Safe Water
- Alternative Author(s)
- Tipu Sultan
- Issue Date
- Water is an essential and integral component of all living beings. It is the basic need of all living organisms. The fresh available water is approximately 3% of the total earth’s water. Only a small percentage (approx. 0.01%) of this fresh water is available for human use. Around 1.1 billion people in the world do not have access to hygienic drinking water and more than 5 million people (3,900 children/day) die each year from water related diseases. It is estimated that by 2025 almost two third of world population is likely to face a moderate or severe water shortage. Therefore, there is pervasive demand to find some ways to purify the water from the contaminants (biological and chemical). One of the solution to tackle the wastewater problem is the reclamation of wastewater. In order to handle such water related problems two approaches are emerging choices: (i) advanced oxidation production (AOP) to deal with chemical contaminants and (ii) ultraviolet (UV) disinfection to deactivate the microorganisms. This thesis is focused on the AOP process and UV water disinfection process.
The wastewater produced by industrial processes contains many dissolved hazardous chemicals. The removal of these hazardous chemicals is requisite for ethical environmental practices. The advanced oxidation process (AOP) is the typically technology used for the removal of these hazardous chemicals. Water treatment via photo-assisted AOP results in the production of hydroxyl radicals . Hydroxyl radicals are highly reactive radicals and they react non-selectively with strong oxidation potential. The hydroxyl radical not only reacts with major contaminants but also with scavenger radicals (HCO1-3, CO2-3, HO1-2, NH2Cl, free chlorine and dissolved organic carbon (DOC)) that are present in the wastewater. Normally, water treatment is focused on a single contaminant, neglecting scavenger radicals, which results in the under-prediction of the contaminant concentration after treatment. A well-proposed optimization problem that considers scavenger radicals is proposed in this work. Moreover, in an ultraviolet hydrogen peroxide (UV-HP) AOP reactor, two process inputs (lamp power and molar ratio of to organic contaminant) are crucial. A response surface optimization methodology that optimizes these process inputs is also proposed in this research. Methylene blue (MB) was used as the major contaminant. It was observed that the overall contaminant concentration at the reactor outlet was strongly dependent upon the scavenger radicals and the lamp power. It was perceived that after a certain limit, increasing the hydrogen peroxide concentration in the wastewater matrix results in an inhibitory effect of hydrogen peroxide. The approach used in this work not only improves the existing UV-HP reactor optimization approach but also provides a better way to model other major contaminants that are present in wastewater.
Water disinfection using an ultraviolet (UV) reactor is an attractive technology because it does not produce by-products. In this work, we investigated the effects of pipe roughness on the performance of a closed-conduit water disinfection UV reactor. In order to incorporate the surface roughness effects, a simple, stable, highly accurate and better than any iterative approximation was adopted in our numerical simulations. The CFD analysis was carried out on the basis of two performance indicators: reduction equivalent dose (RED) and system dose distribution. The analysis was performed by using a commercial CFD tool (ANSYS Fluent ver. 15.0). The fluence rate within the UV reactor was calculated using UVCalc3D. The pipe surface roughness resulted in longer pathogen residence times and higher dose distribution among the pathogens. The effect of pipe surface roughness on RED depends on the Reynolds number and relative roughness. Pipe surface roughness plays an important role because water disinfection UV reactors operate at moderate Reynolds numbers. In addition, lamp positioning within the UV reactor plays an important role in determining the RED of the UV reactor. Search criteria for lamp positioning were also proposed in this research work. The proposed CFD methodology can be used to analyze the performance of the closed conduit water disinfection UV reactors.
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- GRADUATE SCHOOL[S](대학원) > MECHANICAL ENGINEERING(기계공학과) > Theses (Ph.D.)
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