[labnetwork] Reclaimed Water Issue

[Stephen CS Howe]

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

WWW.FABSURPLUS.COM

Japan-Italy-Ireland-USA

On Wed, 2012-10-03 at 13:16 -0400, Kuhn, Jeffrey G wrote:
> 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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