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Stephen is correct that the use of black tubing impedes the growth
of algae (or fungus, whatever it is). Unfortunately, many brands of
black hose start cracking badly after only one year; certainly the
type sold at Home Depot is really quite poor. We had to replace all
of our black hose on the cooling systems. Clear, nylon-reinforced
hose is a lot more durable for water. To stop the growth of "black
goo" we simply include 5% isopropyl alcohol in the cooling water,
which is also a great way to recycle the IPA we use for developer
(IPA+water is used to develop PMMA resist.) If you want to use
something even less toxic, you could recycle waste ethanol.<br>
<br>
<br>
<div class="moz-signature">---------------------<br>
Michael Rooks<br>
<font size="2">Yale Institute for Nanoscience & Quantum
Engineering<br>
<a href="http://nano.yale.edu">nano.yale.edu</a><br>
<br>
<br>
<br>
</font></div>
<br>
On 10/11/2012 03:37 PM, Stephen CS Howe wrote:
<blockquote cite="mid:1349984263.2269.5.camel@samsung" type="cite">
<pre wrap="">Dear Jeff,
I have some experience regarding residue buildup in cooling water tubes.
My input is that it is essential to use black ot dark colored tubing.
The reason for this is organic algal growth will occur if any light can
penetrate the water tubes.
We first used a fungicide when we discovered the algae in our cooling
system, but later discovered that it was not necessary to use a
fungicide if the tubes were dark colored.
The algal growth is typically a brown color like what you describe. We
never did an organic analysis of what grew.
Yours sincerely,
Stephen Howe
Company Owner
SDI Fabsurplus Group
+1 830 388 1071 (Mobile)
+39 335 710 7756 (Italy Mobile)
Skype: Stephencshowe
<a class="moz-txt-link-abbreviated" href="http://WWW.FABSURPLUS.COM">WWW.FABSURPLUS.COM</a>
Japan-Italy-Ireland-USA
On Wed, 2012-10-03 at 13:16 -0400, Kuhn, Jeffrey G wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Good Day All,
The campus water supply at Purdue is quite hard. As a result, we have
seen a significant buildup of scale in our exhaust scrubber, liquid
ring vacuum pumps, and burn boxes. This required periodic shutdowns to
remove the scale, which was expensive and time consuming. We have
since installed a water reclaim system to capture RO, ultrafilter, and
EDI reject streams for use as makeup water for the systems mentioned
above. The water from those waste streams has been softened, thus we
eliminated the scaling issue.
Unfortunately, in solving the scaling issue we have created a new
problem. A brown, slimy, stringy, substance builds up in the storage
tank. It clings to the tank walls, peels off in sheets, and gets
pumped to the points of use where it causes fouling. It settles to the
bottom of the storage tank and coats the tank walls and process
piping. We have to semi-annually drain and clean the tank to prevent
severe fouling at the points of use.
We have verified that the material is not viable (I was surprised by
this). Analysis shows that it is primarily comprised of iron. Purdue
uses ground water that is high in iron for its potable water supply.
In order to protect the water distribution infrastructure, a
monophosphate-based agent is added to the water in order to sequester
dissolved iron. This helps prevent the iron from oxidizing and
precipitating inside the piping system. It would seem that their
sequestering agent is strong enough to prevent the dissolved iron from
being completely removed by IX in the UPW system softeners.
My belief is that dissolved iron becomes concentrated at the RO in the
reject brine stream and then oxidizes in the storage tank, combining
with phosphate to form the slime we are seeing. I do not believe the
ultrafilter or EDI loop reject streams are major contributors to the
problem due to the high purity of these waters. We do not have enough
information yet to prove or disprove my theory.
I realize that this is a rather unusual problem, but I was hoping that
some of you may also have installed reclaim water systems and can
provide some insight as to how to deal with this issue. We are
considering installing a filtration system, but it is expensive and I
am not yet convinced that it will solve the problem.
Thank you in advance for your feedback.
Jeff Kuhn
Facility Engineer
Birck Nanotechnology Center
Purdue University
1205 W. State St.
West Lafayette, IN 47907
Ph: (765) 496-8329
Fax: (765) 496-2018
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