July 24, 2018 - Filter run time does not tell the entire story for conventional granular media filters--here's why. Of course, treatment plant operators want long filter runs to stretch out the time between backwashes. However, if hydraulically lightly-loaded, are the filters really performing well?
Instead, what should be looked at is throughput per unit area before backwash or Unit Filter Run Volume (UFRV):
UFRV = [(Filter Rate) x (Run Length)] / Filter Area
UFRV also provides a metric so filters of different total area may be compared.
Source: AWWA ACE17 SUN01 Workshop, 06/11/17
At this month's KY/TN WPC18, I helped present a paper on Nashville's Umohundro WTP, which is in the National Register of Historic Places. The nozzle-based, monolithic filters built back in 1929are consistently running at UFRVs of 10,000 gal/sf -- Talk about long-term performance! The calculation is provided here.
If you're an operator at a plant with conventional granular filters, I encourage you to calculate the UFRV of all the filters on a regular basis. If the values are closer to 5,000 than 10,000 gal/sf, you should investigate for potential improvements. Further, through trending, you can identify any concerning changes you may have over time.
Call us at ORTHOS if you have any questions! (843) 987-7200
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Remember Orthos' HUGE life cycle cost benefits - At the end of the filter's life cycle (~25 years), in contrast to a complete plastic block or folded sheet metal underdrain overhaul, nozzles are simply replaced, potentially saving $Millions.
"No need to replace the chandelier when all you must do is change out the light bulbs!"
20 YEARS OF EXCELLENCE
ORTHOS is celebrating our 2018 platinum anniversary of ZERO monolithic filter underdrain failures.
Traditionally, the 20-year anniversary gift is breakable china, but that would be like the multitude of plastic block or folded sheet metal underdrain failures--
Providing filtration solutions since 1978, Orthos Liquid Systems, Inc., is the leading manufacturer of nozzle-based filter systems and nozzle products in water/wastewater treatment. With thousands of North American installations in the municipal and industrial markets and millions of nozzles sold, Orthos delivers unparalleled quality and system longevity. Orthos is also the North American master licensee for Schlick® atomizing nozzles for pharmaceutical and other precision application industries. For more information, visit www.orthosnozzles.com or call 843-987-7200.