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TREATMENT PERFORMANCE
The performance of limestone contactor in stabilizing
water is discussed below by presenting data taken before and after
limestone contactors were installed in Mars Hill, Maine; Bredasdorp
and Stellenbosch, South Africa.
(A) Limestone Contactor Performance in Mars Hill, Maine:
Prior to installation of limestone contactor in October 1998,
Mars Hill, Maine exceeded the Lead and Copper Rule (Spencer, 2000).
The 90th percentile lead level was 0.017 mg/L and copper level
was 1.3 mg/L. Part of the cause was believed to be low pH. Installing
a limestone contactor raised the pH and significantly reduced
the lead and copper level.
10 shows that the pH of treated water in Mars Hill increased after
stabilization using limestone contactor.
11 shows that limestone stabilization decreased the 90th percentile
lead level from 0.017 mg/L in Fall 1996 to 0.008 mg/L in Spring
and 0.006 mg/L in Fall 1999.
12 shows that the 90th percentile copper concentration was reduced
from 1.3 mg/L in Fall 1998 to 0.5 mg/L in Spring and 0.65 mg/L
in Fall 1999.
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