Alkalinity is a measure of a solution's ability to neutralize acids to the equivalence point of carbonate or bicarbonate ions. Alkalinity plays a key role in the overall treatability of raw water because it determines the waters ability to chemically react. H. Y. Carson Filter Plant (CFP), operated by the Birmingham Water Works Board (BWWB), receives its raw water primarily from Inland Lake. Inland Lake has very low alkalinity, < 30 mg/L; low total organic carbon (TOC), 2.0-2.5 mg/L; and low

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... bidity, < 2ntu. This combination of water quality parameters creates an interesting dilemma when attempting to improve TOC reduction through enhanced coagulation. Almost two years ago Shades Mountain Filter Plant (SMFP), also owned by the BWWB, underwent a successful coagulant changeover from aluminum sulfate to ferric sulfate to improve their TOC reduction. Upon this success, the BWWB decided that a pilot study at CFP was needed to determine if a coagulant change would be as beneficial there. Although there are many differences between SMFP and CFP, one of the most significant is that SMFP receives raw water that is high in alkalinity, approximately 100 mg/L. This major difference in alkalinity between the two treatment plants played a major role in determining what the most effective coagulant and optimal dose would be at CFP.