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TREATMENT PERFORMANCE - CONTINUED
According to the AWWA guidelines for copper corrosion mitigation,
the bulk water pH must be in the range of 7.1 to 8.0 (Daniels
et al., 2002). 
13 shows the relationship between copper and pH levels at various
sampling points in the Bredasdorp pipe network after limestone
stabilization. The figure shows that the copper level remains
fairly consistent throughout the pH range except for three samples.
All these three samples had a pH value below 7.1. Daniels et al.
(2002) further concluded that copper corrosion is not expected
at pH above 7.1.
(D) Limestone Contactor Performance in Stellenbosch,
South Africa
The effectiveness of a limestone contactor on copper reduction
was also studied in Stellenbosch, South Africa by collecting pH
and copper data at a household sampling point. According to Daniels
et al. (2002), the limestone contactor was operated at a loading
rate of 50% greater than its design capacity due to increased
water requirements in Stellenbosch. The authors implied that this
overloading caused the pH to be lower than desired and led to
higher copper concentrations. The authors further implied that
expanding the limestone contactor increased the pH and decreased
the copper as shown in
14.
Using the data from
13 and
15, Daniels et al. (2002) concluded that the copper corrosion
can be avoided at a pH of greater than 7.1.
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