ACTIVATED
CARBON
From:
owner-aqua-l@killick.mi.mun.ca
To: aqua-l@killick.mi.mun.ca
Sent: 16 July 2004
QUESTION:
I
am looking for someone who would have information on the best activated
carbon for use in shellfish culture.
We
are installing an ozone system because of our poor water quality. Activated
carbon is needed to take out the by-products of the ozone.
Chantal
Gionet
Research shellfish hatchery manager
Coastal Zones Research Institute
Shippagan, NB, Canada
***************
COMMENTS
1:
Recommend
about 4 days of a slow flush to waste on the column, before use (20 or so
bed volumes).
Dallas
E. Weaver, PhD
Scientific Hatcheries
5542 Engineer Dr.
Huntington Beach, Ca 92649
Tel: 714-890-0138
Fax: 714-890-3778
E-mail: deweaver@surfcity.net
URL: http://www.scientifichatcheries.com
***************
COMMENTS
2:
Alternatively
run the water through a UV column. That way you will also remove residual
ozone…this avoids having to keep replacing the activated carbon.
Dr.
Mark Powell
Senior Lecturer
School of Aquaculture
University of Tasmania
PO Box 1370
Launceston, Tasmania
Austraila 7250
Tel:
+61 3 6324 3813
GSM: 0409968920
Fax: 03 63243804
E-mail: Mark.Powel@utas.edu.au
***************
COMMENTS
3:
I
understand the application of UV to break down residual ozone, but are you
saying the UV will also break down the toxic compounds that can result from
ozonating seawater?
Paul Hundley
RMF-Applied Aquatics, Inc.
e-mail: phundley@rmf.com
URL: www.AppliedAquatics.com
**************
COMMENTS 4:
UV will certainly get rid of the residual ozone. As
for the cyclobromo
compounds and the like that are formed I am not 100% sure. My guess
is that it probably would, but it's only a guess; I have never seen any data
on it!
Dr.
Mark Powell
E-mail: Mark.Powel@utas.edu.au
***************
COMMENTS 5:
UV will destroy ozone in the water by exciting the
oxygen molecule and breaking the O3 bond. According to some ozone
manufacturer's recommendations, you would need to have a 90,000 mws/cm2 to
completely destroy ozone. However, it will not remove the hypobromic
acids that are produced when ozone is used in raw seawater. The most
common method for removing this is to run the treated water through
activated carbon. Of course proper testing of the water would need to
be done to determine the length of time that the carbon will last in each
situation. At which point, a preventative maintenance schedule can be
made and put into use.
Amy Riedel
Aquatic Eco-Systems Inc
e-mail: amyr@aquaticeco.com
***************
COMMENTS 6:
I would like to point out that ozone + UV will
oxidize many compounds that are refractory to ozone or UV alone. This
is one of the AOP (advanced oxidation processes) that are used for very
specialized pollution control systems. For example, MTBE (gasoline
additive) is not oxidized by ozone but is oxidized by ozone + UV. This
can create construction material problems with hardware design.
Dallas
E. Weaver, PhD
E-mail: deweaver@surfcity.net
***************
COMMENTS 7:
At the University of Victoria, we use ozone in our FW
recirc system with a residual target of 0.2 ppm. We have UV
downstream, but at the high levels of ozonation we require we found it
wasn't enough and have installed a metering system and H2O2, which is
controlled by ORP sensors. This works very well and as Dallas pointed
out it is an AOP. The stream: Ozone - H2O2 - UV is very effective in
treating water. Hydroxyl radicals are formed in the process, are very
short lived and violent, but do their work well. I haven't been able
to find any papers on this combination in saltwater. Good student
research project.
Gerry Horne
e-mail: gehorne@uvic.ca
***************
COMMENTS 8:
Anybody know any chemical way to reduce or deactivate
H2O2? I'm wondering if Na thiosulfate would "de-oxify" it, since
thio is such a strong reducing agent. H2O2 is great for external parasites,
but the application window is rather short for flushing it out. Therefore,
it would be nice to have an anti-H2O2 chemical on hand.
Syd Kraul
e-mail: kraul@konacoast.com
***************
COMMENTS 9:
Potassium permanganate will catalyze the destruction
of H2O2 producing water, oxygen and manganese oxide/hydroxide.
FeSO4 or FeCl2 also works and is available as a fertilizer. Always keep
some handy incase you overdose and want to kill the activity in a hurry.
Dallas
E. Weaver, PhD
E-mail: deweaver@surfcity.net
***************
COMMENTS
10:
I believe that Vitamin C - ascorbic acid - is
marketed as an environmentally friendly way to neutralize H2O2.
Paul Hundley
e-mail: phundley@rmf.com