Historically, water utilities have managed distribution systems primarily to provide reliability of
service such as adequate pressure and fire flow capabilities. However, increasingly stringent
regulations such as the Stage 2 D/DBP Rule have added a focus on also maintaining acceptable
water quality in the distribution system. Maintenance of distribution system water quality is now
a major challenge for many utilities. Water quality challenges in the distribution system may
include loss of disinfectant residual, increase in disinfection byproducts, biological growth, and
for systems that use chloramines, nitrification.
Storage tanks that are underutilized and have poor mixing characteristics represent a significant
potential for water quality degradation within the distribution system. Computational fluid
dynamic (CFD) modeling and water temperature measurements can be very effective tools to
predict mixing characteristics inside the tanks. This paper focuses on the use of CFD modeling
and temperature measurements to determine mixing characteristics in storage tanks, using a case
study, the City of Virginia Beach. The results from mixing predictions are verified by water
quality data and used to identify the storage tanks with inadequate mixing characteristics and thus
the greatest potential for water quality degradation.
Once the nature of the mixing problem is identified, it becomes easier to make the appropriate
physical and operational modifications to improve mixing in the storage tanks. This paper also
presents general recommendations for improving mixing, and reports on actual physical
modifications that have improved mixing characteristics in a storage tank.
Includes table, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 870 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 14 |
| Published : | 11/01/2002 |
