EXAMPLE OF CONSTRUCTION AND O&M
COSTS - CONTINUED
It was estimated that the yearly cost of limestone replacement
at Mars Hill, Maine is US$200 compared to US$2,500 for soda ash
(Spencer, 2000). 
16 and 
12 show comparison of cumulative cost between limestone, lime
and sodium carbonate over a 10-year period for the Makwane Plant
in South Africa. The figure and table demonstrate a significant
savings when using limestone contactor over lime and sodium carbonate
that more than offset higher capital costs.
Financial assessment was carried out by CSIR to investigate the
viability of the Simplified SSP to stabilize the typical raw water
in Stellenbosch, South Africa. The viability of the Simplified
SSP was determined theoretically using the computer model developed
using JAVA, STASOFT and WATCHEM described earlier.
Comparison of operating costs was made between each Simplified
SSP variation and between the Simplified SSP and conventional
stabilization (based on achieving the same final water quality).
The operating costs were determined using the required chemical
dosages and chemical costs.
17 shows cost comparison between the Simplified SSP and conventional
lime/CO2 stabilization. Both were based
on treating the raw water characteristics as shown in
13 until a final alkalinity of 50 mg/L and a CCPP of zero were
achieved. The chemical prices were based on the current cost at
Stellenbosch, South Africa in November 1999 shown in
14.
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