The bacteria that give biological filters
their activity are located primarily on the
media; thus media sampling and analysis
is necessary. Use of online and off-line
monitoring tools such as luminescent DO
and AOC can be used to provide indirect
indications of biological activity, but they do
not directly quantify the amount or activity of
the bacteria on the media. Media sampling is
not as convenient or easy as sampling water,
but preliminary data from this study suggests
that samples collected from the surface of
biological filters may be adequate as opposed
to media coring or excavation.
ATP—ATP (adenosine triphosphate) is a
biochemical present in all living things.
Its concentration on a media sample is
an indication of the quantity of active
microbes present. It is easily measured using
commercially available instruments provided
by companies including Promega and
Luminultra. These instruments measure ATP
using the same biochemistry used by fireflies
to generate light.
Conclusion
The above tools represent just some of the
practical techniques for managing biological
filters and can readily be implemented at
treatment plants. Others require specialized
laboratories to provide useful and important
data. The optimal combination of these
different techniques will depend on water
quality objectives, treatment processes
used to attain these objectives, and utility
resources. The use of these tools will help
utilities monitor, control, and optimize
biological filters to achieve water quality
objectives cost-effectively and dependably.
For more information on this project,
contact Hsiao-wen Chen at 303.347.6103
or hchen@WaterRF.org.
Diane Nelsen of CDM prepares a media
sample from a biological filter for ATP
analysis. Photo Credit: Dung Nguyen
