THESIS
2015
xvi, 112 pages : illustrations (some color) ; 30 cm
Abstract
The supply of clean drinking water is considered as a major public health milestone for our
generation. Waterborne diseases are still the third leading cause of death. The recent outbreaks
of Legionella in the US and Hong Kong demonstrate the long viability of bacteria in
contaminated water distribution system. Existing disinfection technologies rely on the use of
chemicals to safeguard water production, which raises many questions other than disinfection
effectiveness solely. The Pulsed-Electric Field (PEF) technology is widely used in fluid food
sterilisation processes. Microbial cell walls will be elongated and suppressed under a pulse
electric field. This causes irreversible damage to the microbial cell wall. Inner structures such
as cytoplasm of the microbial cell wall will...[
Read more ]
The supply of clean drinking water is considered as a major public health milestone for our
generation. Waterborne diseases are still the third leading cause of death. The recent outbreaks
of Legionella in the US and Hong Kong demonstrate the long viability of bacteria in
contaminated water distribution system. Existing disinfection technologies rely on the use of
chemicals to safeguard water production, which raises many questions other than disinfection
effectiveness solely. The Pulsed-Electric Field (PEF) technology is widely used in fluid food
sterilisation processes. Microbial cell walls will be elongated and suppressed under a pulse
electric field. This causes irreversible damage to the microbial cell wall. Inner structures such
as cytoplasm of the microbial cell wall will diffuse out of the cell through enlarged pores. Thus,
the microbial cell is no longer able to survive. PEF disinfection can effectively inactivate the
bacteria in food products without altering the taste, colour, and nutrients. However, current
PEF devices are bulky and require high input voltage pulse, which is not suitable for household
usage. In this study, the PEF electrodes were redesigned for using under low input voltage.
Two electrodes, multi-layered electrode and spiral-wound electrode were successfully
designed, fabricated, and tested. The electrodes were able to achieve 99% bacteria reduction.
Parametric effects to PEF disinfection performance were also studied. The parameters include:
E-field direction, pulse width, and applied voltage. At higher applied voltage and longer pulse
width, the PEF disinfection performance is better.
Post a Comment