AWWA ACE56256

The Connecticut Water Company (CWC) owns and operates the Stafford Springs Water Treatment Plant (SSWTP), located in Stafford, CT. The SSWTP is a 1.0-MGD facility that utilizes chlorine preoxidation, alum coagulation, Pulsator upflow clarification and GAC monomedia filtration. The facility produces high quality water that meets all current drinking water regulations, but like many utilities, may not meet all requirements of future regulations. Metcalf & Eddy Inc., in conjunction with CWC, conducted a feasibility study to determine the status of the plant with respect to current and expected regulations, and to determine the process improvements that would be necessary with all facets of pending regulations. A significant constraint was that the plant must remain in full service during construction of any recommended improvements. A primary goal of the study was to examine alternate preoxidants for chlorine in order to achieve compliance with the Disinfectants/Disinfection Byproducts Rules (D/DBPR). A jar test program and subsequent intra-plant sampling program confirmed that prechlorine was forming significant levels of DBPs within the plant. The SSWTP raw water quality necessitates a preoxidant, and the most promising preoxidants appeared to be chlorine dioxide or potassium permanganate. Each preoxidant was investigated in further detail and compared on the basis of feasibility and cost. Another major objective of the study was to determine the most feasible enhanced disinfection process for compliance with potential Cryptosporidium inactivation requirements of the Enhanced Surface Water Treatment Rule. A list of alternatives was screened down to the three most promising options: intermediate ozonation, ultraviolet disinfection, and replacement of Pulsator clarification or immersed-membrane microfiltration. Conceptual layouts were developed for each of the alternatives and all were compared on the basis of disinfection efficiency, construction considerations, capital cost, operations cost, and present worth. The study resulted in a list of recommended improvements for the SSWTP that will result in compliance with the D/DBPR while maintaining effective disinfection. Full-scale testing of chlorine dioxide was recommended, and ultraviolet disinfection was selected as the most feasible enhanced disinfection process for future installation. A phased implementation plan was then developed to assist the CWC with operations and fiscal planning. Includes 3 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

06/16/2002

Number of Pages:

19

File Size:

1 file , 480 KB