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Over the past several years the Sweetwater Authority has piloted and full scale testedseveral treatment technologies for the treatment of surface waters with high bromide andtotal organic carbon (TOC) concentrations. These treatment systems includedconventional treatment with enhanced coagulation, ozone with pH suppression, chlorinedioxide, dissolved air floatation (DAF), microfiltration (MF) membranes, ultrafiltration (UF) membranes, and MIEX.Each of these treatment systems, while viable solutions if operated under certainconditions, presented particular challenges. During the testing of these systems it becameapparent that no single treatment solution would work for all of the issues thatSweetwater Authority faced.The raw water supply to the Perdue Water Treatment Plant is the Sweetwater Reservoir.This surface water impoundment receives local run-off and can provide raw water insufficient quantities to comprise 20% of the average 10-year demand cycle. However,though it is a low cost water supply there are some significant difficulties associated withtreating it. Typical bromide concentrations can be as high as 0.8 mg/L and TOC can beas high as 8 mg/L with specific UV absorbance (SUVA) greater than 2 L/mg-m. Oftenenhanced coagulation requirements can be met with a SUVA value of less than 2.0, butfor a significant period during high demands and poor raw water quality this can not bemet. Disinfection byproducts also becomes a concern with TTHM formation in excessof 120 ppb, even with chloramines in the distribution system. Additionally, following thedosing of ammonia to form chloramines, after only 2 1/2 minutes of free chlorine contactTHM levels will continue to rise by over 30 ppb within the plant and distribution system.With these issues and pending regulatory requirements, it is imperative that SweetwaterAuthority selects the appropriate treatment technology.All of the above mentioned treatment technologies offered differing benefits and ways tomeet the regulatory requirements. While there is no silver bullet for the issues that arefaced, there are combinations of technologies that will allow Sweetwater Authority tomeet the regulatory requirements. However, just meeting the regulatory requirements isnot enough; it is equally important to meet the economic constraints that SweetwaterAuthority, like all utilities, are facing. This paper sheds some additional lighton these issues and provide another potential means and experience set for otherorganizations to utilize during their selection process. Includes figures.

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Edition: Vol. - No. Published: 11/15/2004 Number of Pages: 8File Size: 1 file , 370 KB