Hot Topic: Turbidity

Nov. 7, 2012

What is the most effective way to reduce turbidity and color from river water?


Posted by mikemarkic on 7/30/2012 at 9:12:13 AM
What is the most effective way to reduce turbidity and color from river water?

NTU 30, CTU 35. The NTU needs to be reduced to 1 or less.

Is there an effective media to get these results without using flocculation?


Gary Schreiber, CWS VI: 7/30/2012 3:26:35 PM
You need to first know what the particle size is that is causing the turbidity and you need to know what is causing the color. Failing getting a complete analysis you could bench test the water using a multimedia filter for the turbidity and at the same time see if that reduces the color to an acceptable level.

If it handles the turbidity, but not the color, then bench test a color removing ion exchange resin, which would be an anion resin in the chloride form. Not just any anion resin, but one that is designed for color or tannin removal. I hate recommending anything specifically until you know what the detailed analysis of the water is or at the bare minimum bench testing the media you believe will do what you want.

mikemarkic: 7/31/2012 6:56:11 AM
The source of water is river water. The quality of water is always changing. I have done three turbidity tests so far with different results. The turbidity can be silt, sand, clay depending on seasonal changes, rain or boat activity.

The color is definitely organic, again levels of color fluctuate. I am presently using a multi-media filter, carbon filter and two inline cartridge filters (5 and 1 mic), but they plug up every couple days.

I am looking for a media that filters down to approximately 5 microns. The organic color is plugging carbon filter every two to three months. Carbon smells like swamp when replaced.

The system is being used to prefilter water for a chlorine disinfection system for a campground.

Gary Schreiber, CWS VI: 7/31/2012 7:26:20 PM
Good luck. Maybe someone else on this board has an idea.

scruffy dee: 8/9/2012 3:04:44 PM
Slow sand filter?

Gary Schreiber, CWS VI: 8/9/2012 6:31:06 PM
Never seen a sand filter, slow or fast, that can filter down that far. Multimedia filter (sand/anthracite) will coag or flocc assist may be able to.

mikemarkic: 8/9/2012 8:53:04 PM
I am going to try super chlorination (5 ppm) followed by next-Sand filter, then GAC filter, then dual BB20 filters (5 and 1 micron absolute cartridges). The water has no coliform or E. coli bacteria. I will find out in a week how this works and retest turbidity and color.

Gary Schreiber, CWS VI: 8/10/2012 6:07:32 PM
Good luck and let us know how you come out.

Rex Johnson: 8/19/2012 8:59:33 PM
I know this reply is dated since your post, however, I have not seen any recent follow ups. First of all, it would be extremely beneficial to all of us if you could please include all values you have found during your testing. The more information provided enables the board to respond more accurately to the specifics of your issue.

I understand your problem is really three problems. When dealing with rapidly changing water sample values one must be able to treat for all of them. If you have silt, then you must be able to treat for silt; if you have sand, then you must treat for sand; if you have clay, then you must be able to treat for clay. If the turbidity is constantly fluctuating, you must be able to treat for all possible permutations of that fluctuation.

This is a most vexing problem since there are three different sets of problems. I’ll bet that each scenario has different amounts of each contaminant issue. The only solution is a treatment system which will address the worst possible case for any of the above.

For a water treatment dealer this is the worst situation to become embrangled. Your goal is perfection. Your enemy is the water rules change all the time.

Your customer wants a simple, inexpensive fix to the problems. You must be honest and advise him (her) of the realities of life and water treatment. Unless they are willing to pay for each treatment system you will only be able to treat some of the water some of the time. Or, you could treat some of the water all of the time, but never all of the water all of the time due to the differences in water quality.

My best advice to you is to be completely honest and inform your client of all the issues at hand and ask them which cure they want the most. That’s the only way you can proceed. Include your client on all aspects of delivery systems and find out which of them are most beneficial to their needs.

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