The University of Central Florida is conducting a $3,000,000 Tailored Collaboration Project to
determine the effects of blended water quality on distribution system water quality. Finished
waters from seven different processes are blended in varying ratios before distribution to
eighteen pilot distribution systems (PDS) in a facility that includes 8500 ft2 of roofing and 4500
ft2 of cement pad. The facility is operated continuously. Processes include conventional groundwater, softening, enhanced surface water, integrated membrane system and reverse osmosis
treatment. The PDS were made from galvanized, cast iron, lined cement and PVC pipe taken
from actual distribution systems. The study found that alkalinities less than background (200 mg/L
CaCO3) have resulted in release of apparent color to 50 CPU. Apparent color release is due
almost totally to particulate iron, and appears independent of pH, LSI, calcium and all other
parameters associated with CaCO3 associated indexes except for alkalinity, Color release is also
positively correlated with chloride and sulfate concentrations. Color release has continued
through six months of equilibration and 15 months of field testing from CI pipes receiving less
than background alkalinity. Total and free chlorine dissipation was accurately predicted by
modeling residual as a function of pipe material, UV-254, temperature and time. Field data and
model projections have shown: the dissipation rate of Total or free chlorine is approximately
an order of magnitude greater in galvanized and CI pipe than in lined cement and PVC pipe;
maintenance of required residuals in galvanized and CI pipe is practically impossible in
summertime conditions; and, pipe material is the most significant factor affecting residual
maintenance for expected water quality conditions in distribution systems. Ferric hydroxide
and cupric hydroxide appear to be the controlling solid films based on surface and equilibrium
analyses. Biological stability did not change as a result of film disruption as indicated by
apparent color release. Field investigations will continue until June 2003. Includes tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 5.1 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 18 |
| Published : | 06/15/2003 |
