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Environmental Engineering Research 2000;5(4): 207-212.
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REDUCING RESIDUAL ALUMINUM CONCENTRATION AT WATER TREATMENT PLANT BY IMPROVING FILTRATION PERFORMANCE |
Seung-Hyun Kim1†, and Cho-Hee Yoon2 |
1Department of Architectural, Civil, and Environmental Engineering, Kyungnam University, Masan 631-701, Korea 2Department of Fine Chemistry and Chemical Engineering, Kyungnam University, Masan 631-701, Korea |
Corresponding Author:
Seung-Hyun Kim , |
Received: March 21, 2000; Accepted: November 20, 2000. |
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ABSTRACT |
This study monitored residual Al concentrations at water treatment plant and evaluated the monitoring result in the aspect of the treatment performance. A water treatment plant, which produces 270,000 m3/day, was selected for this study. This plant, which relies on river for its raw water, used alum and PAC1 for coagulants (average dosage of 2.9 mg/L as Al). Residual Al concentrations were monitored at various treatment processes over two monitoring periods extending 2 years (November 1994-April 1995 and February-June 1996). After the first monitoring period, it was found that residual Al concentrations of treated waters exceeded 0.2 mg/L of the Korean Drinking Water Quality Standard (KDWQS). Average Al concentration in raw water was 0.07 mg/L (0.03 mg/L of dissolved Al, 0.04 mg/L of particulate Al). It increased to 0.39 mg/L (0.06 mg/L of dissolved Al, 0.33 mg/L of particulate Al) after sedimentation and decreased to 0.34 mg/L (0.05 mg/L of dissolved Al, 0.29 mg/L of particulate Al) after filtration. It was speculated from this result that filter performance was unsatisfactory and inefficient filtration caused high residual Al concentration in treated waters. This speculation was supported by poor turbidity removal efficiencies of filters. After the first monitoring period, the plant renovated its filters and added GAC contactors into the plant. The second monitoring followed the renovation. According to the second monitoring results, average Al concentration in raw water was 0.26 mg/L (0.11 mg/L of dissolved Al, 0.15 mg/L of particulate Al). It increased to 0.32 mg/L after sedimentation (0.08 mg/L of dissolved Al, 0.24 mg/L of particulate Al), and decreased to 0.11 mg/L after filtration (0.06 mg/L of dissolved Al, 0.05 mg/L of particulate Al). It decreased further through GAC filtration to 0.08 mg/L (0.05 mg/L of dissolved Al, 0.03 mg/L of particulate Al), satisfying the KDWQS. This study showed that residual Al concentration in treated water could be lowered by improving filtration performance. |
Keywords:
Al | dissolved fraction | filtration | particulate fraction | turbidity removal |
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