AWWA MTC57657

The effect of blending different water qualities on distribution system water quality wasinvestigated in this field study. Waters produced from five different treatment systems; aeration(G1), NF (G4), CSF-O3-GAC (S1), IMS (CSF-NF, or S2) and high pressure reverse osmosis (RO) were blendedand distributed to 18 different pilot distribution systems (PDS). G1, G4, and RO source waterswere taken from the same groundwater. The RO source was augmented with salts to simulateseawater. The S1and S2 source waters were taken from the same surface water. The PDSsconsist of PVC, galvanized, lined ductile iron and cast iron pipes taken from existing distributionsystems and had a 5-day HRT. Chloramines were added to meet CT and residual requirements.AOC, BDOC, HPC are measures of suspended biological activity. PEPA measures attached filmbioactivity.The S2 and G4 AOC are essentially equal, but the RO AOC is reduced and less thanother treatments. S1 and S2 AOCs are equal. PDS biostability order is G1<G4=S1=S2<RO.During the wet season, raw surface water TOC increased significantly, and S1 AOC was alsoincreased. BDOC was not correlated to HPCs and BDOC sensitivity was not adequate to assessbiostability among treatments. PDS nitrification occurred in June and July 02 as the result of aloss of residual at 25oC to 30 oC and pH 7.8 to 8.3. During nitrification, the HPC valuesincreased significantly, D. O. decreased; nitrification was nearly complete, which provided acarbon source for heterotrophs as the system became microaerophilic. AOC and Pepa assessmentof biostability indicated HP RO increased biostability of finished water, but NF did not improvebiostability relative to advanced surface water treatment at normal conditions. NF did improvebiostability during the wet season. Includes 19 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

03/05/2003

Number of Pages:

18

File Size:

1 file , 2.7 MB