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LIST
OF CONTENTS
Introduction
Process Description
Typical
Contactor
Design
Criteria
Photos, Plans & Specs
Treatment
Performance
Operational
Skills
Automation
Potential
Advantages
Limitations
& Concerns
Pilot
Plant Objectives
Costs
References
Contacts & Facilities
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EXAMPLE OF CONSTRUCTION AND O&M
COSTS
9 shows cost estimates of limestone contactors built in Port Simpson,
British Columbia for flocculation and corrosion control purposes.
The total cost to construct both of these contactors was $CND
140,000. The high total cost was due to the facility being remote
from large towns causing increased cost in transporting construction
materials. It was estimated that 90% of the limestone cost was
for transportation. The total cost would be approximately 50%
lower if the facility were close to large towns.
The cost for the two contactors was estimated based on the design
criteria listed in
10. Different design criteria were used for these contactors.
This may be due to higher requirement on the pH and alkalinity
content of the water treated used for corrosion control. Therefore,
it is designed to have a contact time slower than that of the
contactor used for flocculation.
A cost comparison was made between a limestone contactor and
soda ash for treating an average of 1.1 MLD of water (1.6 MLD
maximum) at the Mars Hill, Maine water treatment facility. It
showed that the capital costs between the two options were similar,
in the range of US$ 40,000 (Spencer, 2000). De Souza et al. (2000)
found that the capital cost for limestone contactor installation
is much higher than adding lime and carbonate for treating 6 MLD
water at Makwane Treatment Plant in South Africa. Refer to
11 for cost comparison. Even though the capital cost for limestone
contactor is high, it is less expensive to operate and maintain
compared to feeding soda ash and lime (Spencer, 2000 and De Souza
et al., 2000).
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