碩士 / 國立中央大學 / 環境工程學系 / 86 / The microbial-related problems frequently encountered in cooling
water systems including bio-corrosion, bio-fouling, and causing
Legionellosis. This study aimed to investigate and identify the
microorganisms presented in real cooling water systems at
various industrial sites as well as to evaluate the feasibility
of reusing wastewater from treatment plants as cooling water
make-up. Water samples and metal coupons of carbon steel and
brass collected in field and laboratory tests were analyzed in
order to realize the relationships between water qualities and
operating problems of cooling water systems. Furthermore, the
effects of ozonation on the control of microbial-related
problems were also investigated.The evaluation of water
qualities and water stabilization indexes indicated that the
effluents from the units of secondary biological treatment
process, tertiary filtration, and chlorination of Ming-Shen
Community Wastewater Treatment Plant (MSCWTP) were suitable for
reuse as cooling water. Similarly, the effluent from tertiary
chemical coagulation process of Da-Yang Industrial Park
Wastewater Treatment Plant (DYIPWTP) was also adaptable as
cooling water make-up. However, considering the effects of
scale, corrosion and fouling, the treated wastewater from MSCWTP
was more suitable for reuse than that from DYIPWTP as cooling
water. The investigation of microorganisms presented in real
cooling water systems at various industrial sites showed that
one case of Legionella contamination was detected out of 9
cooling water systems in this study. In addition, the groups of
bacteria were identified at these cooling water systems
including Serritia, Pseudomonas, Bacillus, Acinetobacter,
Aeromonas, and Vibrio. The genera of algae such as Oscillatoria,
Melosira, Colestrum, Cosmarium, Lyngbya, Trachelomonas,
Celastrum, and Diatom were also found. Among these organisms,
generally, Pseudomonas, Bacillus and Diatom were slime forming
microorganisms. The water samples from the effluent of MSCWTP
were detected the existence of Legionella and sulfate-reducing
bacteria. Therefore, in order to protect public health from
respiratory diseases and inhibit the bio-corrosion, appropriate
biocide control as well as proper design and operation of
cooling tower and heat exchanger are necessary when reusing the
effluents of MSCWTP as cooling water. Ozonation of cooling
water has been known for its excellent biocidal effect, and the
results of this study were coincident with that. In pilot study,
constant presence of 0~0.05 mg/l ozone in cooling water system
could remove 97.8% total count of bacteria. The surface
observation of metal coupons by scanning electron microscopy
showed that ozonation could inhibit bio-fouling. In laboratory
study, it found that intermittent addition of ozone could
confine the growth of bacteria when using sewage effluent as
cooling water make-up, however, the corrosion rate might be
increased after ozonation.Keyword: cooling water, bio-fouling,
ozonation, wastewater reuse.
| Identifer | oai:union.ndltd.org:TW/086NCU00515018 |
| Date | January 1998 |
| Creators | Lee, Shin- yi, 李欣怡 |
| Contributors | Dyi-Hwa Tseng, 曾迪華 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 1 |
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