AWWA ACE68674

Prior to the compliance deadline for the Stage 1 Disinfectants/Disinfection Byproducts Rule(D&DBPR), Cobb County-Marietta Water Authority (CCMWA) had observed seasonally elevated DBP concentrations in the portion of thedistribution system served by the Wyckoff WTP, with annual averages of 63 micrograms per liter(ug/L) for total trihalomethanes (TTHM) and 71-ug/L for haloacetic acids (HAA5). Additionally,individual sample values at the Stage 1 D&DBPR sample locations had been observed during thesummer months to be as high as 120-ug/L for TTHMs and 98-ug/L for HAA5, prior to 2002. Dueto the fact that several consecutive systems supplied by CCMWA also purchase water from othersources, and some areas in the distribution system have extended hydraulic residence times,simple solutions such as decreasing chlorine dose or switching to chloramines are not viableoptions. In late 2001, CCMWA and its consultant, CDM, began a series of pilot studies to investigatelong-term solutions that would reduce DBP precursors at the Wyckoff WTP and allowcompliance with the Stage 2 D&DBPR. The team performed an initial 12-month pilot study todetermine the effectiveness of ozone, biofiltration, and advanced oxidation to reduce DBPprecursors in the finished water. Supplemental investigations into alternate treatment technologiesincluding magnetically enhanced ion exchange (MIEX®) and a bench-scale analysis of post-filternanofiltration (NF) were also conducted. In the summer of 2005, an additional pilot studyinvestigating post-filter granular activated carbon (GAC) adsorption was conducted. This studywas followed by a final pilot study in the summer of 2006, investigating post-filter NF. This paper presents results and compares these treatment processes. Includes tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2008

Number of Pages:

38

File Size:

1 file , 1 MB