CT Blowdown Re-use Options?

[ProjectEng]

Blowdown seems like such a waste. We have over 3,000gpm of 4 - 5 cycle blowdown.

Any ideas on how to use it instead of pumping it to the sewer?

 

[quark]

What are the TDS and hardness levels? With 4 COC I assume somewhere around 500ppm of TDS. If hardness is not too high above 200ppm you can use it for gardening. We are using even RO reject (2000 ppm TDS) for gardening and flusing applications.

Don't forget to treat for pH.

Regards,

Repetition is the foundation of technology

 

[ProjectEng]

At 4 COC, I estimate total hardness at 1000ppm and conductivity at 2400. pH should be close to 7.

 

[WaterDoc]

I am in the field of industrial water treatment and deal with the potential reuse of reject (blowdown / bleedoff) water ... I would need more info as to the actual water chemistry of your 4-5 cycle bleed/blowdown water ... specifically: pH, Ca & Mg hardness, alkalinities, silica, sulfates, phosphates, TDS, etc. -- also, assuming your cycled water is from a "chemically treated" system, what chemistry is imparted by it ... and, finally, what/where is your cycled water's intended use?

Based on the above info, possible use of your cycled water could be evaluated.

 

[smile1]

The key to this puzzle is external pretreatment to produce the quality of water needed for the application if you wish to minimize water consumption. Depending on the influent water analysis, it is possible to have a cost effective system for water pretreatment and minimal water losses. If you would like to discuss further, let me know.

keith@midsouthmaterial.com

 

[DeltaCascade]

Short of working to minimize cooling tower blowdown (as smile1 said) to maximize concentration of impurities without compromising cooling water treatment program, you must eventually blowdown to get rid of the concentrated minerals. A necessary "evil".
Cooling towers are often the process which can take other waste streams from your site and use it there ... reducing waste from other areas.
Cooling tower blowdown reduction can be achieved by improving make-up water quality (as above), by sidestream softening (not without its complications), or reverse osmosis and recyle (expensive and reject stream would likely need to be sewered, and it would be very salty), etc.
Good luck.

 

[ajw160]

4 to 5 cycles is on the low side for a cooling tower application (if you're talking about boiler blowdown the game is already over with respect to running any type of effective treatment program); it is difficult to say what can be done without knowing what is in your city/well makeup, but generally significant water savings can be achieved by going to a partially-softened makeup source or by using acid feed if hardess/scale are your main concerns (as is most common).

Another common limiting factor is often times Silica which can form glass like deposits that will also drastically limit your heat exhange capabilities.

More information is needed but the answer you're looking for may be to simply make better use of the water by running higher cycles.

 

[treatwa]

Dear waterdoc,

I have a Bachelor's Degree in Chemical Engineering. Having had worked for over a year, as an Chemical Engineer, in the Water Treatment Chemicals department of Industrial Water Treatment organisation, I have developed a keen interest in Water and food treatment technologies.

As such having moved to canada six months ago i am interested in pursuing a career in the same, to further investigate and enhance my knowledge of this fascinating field.

Further to the foregoing, I am kindly requesting you to furnish me with detailed information as to what is the necessary experience, technical knowledge and qualification an employer would look for when hiring a chemical engineer for his water treatment firm .
Also if possible like person to contact and the related courses that could help me achieve my goal, by taking up such a program, if available, at the University.

My contact info are detailed below for your kind correspondence.

Thanking you in advance for your time in consideration and eager to hear from you at your earliest convenience.


SHEETAL PAWAR

e-mail : shigem_26@hotmail.com

 

[DeltaCascade]

treatwa, please start a new thread to avoid changing and diluting the subject quality here. Perhaps in another forum on this site.
But, you are at the right place .. just keep reading and the answers to your questions will come. Good luck.


Proj Eng - if you post a detailed analysis of make-up water quality, we/I can tell you what your maximum possible cycles (minimum possible blowdown rate) will be, and make suggestions for make-up water treatment to increase cycles further. To expand on above comments, there is a good chance that you can double your cycles now, with good application of a cooling water treatment program. In some cases. cooling water calcium concentrations as high as 1200 ppm as CaCO3 can be tolerated (you gave us the total hardness, what is the calcium hardness?).
It is not uncommon to have cooling tower cycles high enough that the only blowdown is that from drift and windage liquid losses out of the tower, where metered or intentional blowdown is negligible. This typically occurs at 12-15+ or so cycles, depending upon tower demister performance and other factors.
Talk to your water treatment vendors.
Have you been able to effect any improvements?
Good luck.