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Comparison of UV-C and Vacuum- UV induced AOT on the acute mortality of microalgae.
KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
2013 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Advanced oxidation technology (AOT) has been used to destroy microorganisms in ballast water by breaking down the cell membranes. The primary objective of this study was to determine the effects of a ballast water treatment system that uses a combination of UV-C (λ=254 nm), Vacuum-UV (VUV; λ=185 nm) and photocatalytic titanium dioxide (TiO2) on a freshwater algae, Pseudokirchneriella subcapitata, and a marine algae, Tetraselmis suecica. The coupling of a semiconductor, such as TiO2, with a UV source is known as an advanced oxidative technology (AOT). To test the effects of TiO2 and wave length on algae, dose-response experiments were conducted to determine the species median lethal dose (LC50) for each of the following treatments: UV-light emitted at 254 nm (UVλ=254 nm), UV-light emitted at 254 nm in the presence of TiO2 (AOTλ=254 nm), and UV-light emitted at λ=254 nm (90 %) and 185 nm (90 %) in the presence of TiO2 (AOTλ=185 + 254 nm). In both species, TiO2 significantly increased mortality, most likely due to the biologically harmful radicals generated at the TiO2 surface. The addition of the 185 nm wavelength significantly increased cell mortality in P. subcapitata, but not in T. suecica. Across all three treatments, P. subcapitata was more sensitive than T. suecica. The secondary purpose of this study was to assess the applicability of ImageJ, an image analysis software, for highthroughput data to analyze the effectiveness of ballast water treatment. ImageJ has been used to rapidly and accurately perform cell Live/Dead analysis; however, several hurdles were identified.

Place, publisher, year, edition, pages
, TRITA-LWR Degree Project, ISSN 1651-064X ; 2013:24
Keyword [en]
Advanced oxidation technology, vacuum UV, UV-C, titanium dioxide, algae, Pseudokirchneriella subcapitata, Tetraselmis suecica, ballast water treatment
National Category
Civil Engineering
URN: urn:nbn:se:kth:diva-171839OAI: diva2:844685
Educational program
Degree of Master - Environmental Engineering and Sustainable Infrastructure
Available from: 2015-09-21 Created: 2015-08-07 Last updated: 2015-09-21Bibliographically approved

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