THESIS
2014
xii, 119 pages : illustrations ; 30 cm
Abstract
Many microorganisms including known waterborne pathogens (e.g., Legionella pneumophila,
Pseudomonas aeruginosa, Aemonas sp and Mycobacterium sp) could thrive in municipal water supply
network and building water distribution system. Also, some open water features such as water
ponds and fountains are common in modern architecture and interior design. When
improperly maintained, they could become a reservoir for microbes and pests. Chemical
disinfectants (i.e., chlorination) are often used, but can lead to malodour and material
corrosion. This work examines an alternate water disinfection technology based on pulsed-electric
field (PEF). Microbes subjected to pulsed-electric field often experience a change in
cell permeability and on occasion irreversible poration on the cell mem...[
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Many microorganisms including known waterborne pathogens (e.g., Legionella pneumophila,
Pseudomonas aeruginosa, Aemonas sp and Mycobacterium sp) could thrive in municipal water supply
network and building water distribution system. Also, some open water features such as water
ponds and fountains are common in modern architecture and interior design. When
improperly maintained, they could become a reservoir for microbes and pests. Chemical
disinfectants (i.e., chlorination) are often used, but can lead to malodour and material
corrosion. This work examines an alternate water disinfection technology based on pulsed-electric
field (PEF). Microbes subjected to pulsed-electric field often experience a change in
cell permeability and on occasion irreversible poration on the cell membrane that leads to cell
death.
A point-of-use PEF device using a portable circuit and electrodes was designed and fabricated.
Laboratory studies showed that the PEF is effective against 90% of common Gram-negative
bacteria (i.e., Escherichia coli) commonly found in water without changing the water quality (i.e.,
pH, hardness and ion content). The device was also tested in Queen Elizabeth Hospital’s
drinking water system and a water feature located at Hong Kong University of Science and
Technology (HKUST) to measure its effectiveness under practical use conditions. The field
test studies showed that the point-of-use PEF device has effectively inactivated the total
number of coliform bacteria in the water.
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