Full Description

The Stafford Springs Water Treatment Plant (SSWTP) is a 1.0-MGD facility owned andoperated by the Connecticut Water Company (CWC). The plant utilizes Pulsator clarificationand filtration through four feet of mono-media granular activated carbon (GAC). The GAC filtermedia is changed out every three years for taste and odor control.A previous study done by Metcalf however, a relatively high dose of chlorine dioxide was needed.Disinfection byproduct levels in the distribution system declined significantly as a result of thesubstitution of chlorine dioxide for pre-chlorine.This study was unique in that the chlorite removal ability of both newer and spent GAC filtermedia was evaluated side by side in a full-scale application. In order to examine the influenceof GAC age and natural organic matter (NOM) saturation on chlorite removal, the media intwo of their three GAC filters was replaced before the start of the full-scale trial. The 3-year oldmedia in the third filter was not replaced, thereby providing an opportunity to evaluate chloriteremoval through new GAC filter media with filter media close to NOM saturation. The filtercontaining the newer GAC media removed the majority of chlorite, while the filter containing 3year old spent media exhibited a limited capacity for chlorite removal which continued todecline throughout the study.The study concluded that chlorine dioxide could be a viable alternative to prechlorination;however, it was not considered favorable to carry a chlorine dioxide residual through the plantdue to the high doses required. The GAC filters were expected to control chlorite levels andcompliance with the 1.0 mg/L chlorite maximum contaminant level (MCL) in finished water;however, modification of the GAC filter media replacement schedule was recommended. Includes 7 references, tables, figures.

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Edition: Vol. - No. Published: 11/15/2004 Number of Pages: 20File Size: 1 file , 680 KB