Precipitation of drinking water after boiling 3

[hamlton]

I run a small potable water treatment plant which uses convetional method (flocculation, sedimentation and filtration), chemicals used are alum and lime and HTH, all are added at once in the floculation chamber, turbidity,pH and residual chlorine levels after treatment are all ok. If you boil the water it precipitates some whitish stuff and is cause some itching after taking a hot bath (what should i do). The chemistry of the treated water is as follows;
Total alkalinity = 140ppm
Sulphate = 164ppm
calcium = 23.9ppm
magnesium = 29.1ppm
The water is sourced from a river.

 

[orenda1168]

Hamilton:

What is the combined chlorine (chloramine) concentration (total chlorine minus free chlorine)? If this is above 0.2 ppm or so, it's capable of causing the itching problem.

Is the whitish precipitate calcium sulfate?

Orenda

 

[sbush]

Have you tried boiling the raw water to see if you get the same precipitate? Check the aluminum level in the effluent to see if you are overfeeding alum.

S. Bush

http://www.water-eg.com

 

[hamlton]

Orenda, i have send the sample of the precipitate for analysis to findout. Your suggestion to check for choramines is a bright one i will do likewise - thank you so much

Sbush, what level of aluminum is expected in the effluent if it is overfed? - thank you.

 

[GarySCWSVI]

When you boil the water it will cause the minerals, etc. in the water to become visible. It will likely, by the analysis you get, be a combination of those minerals.

Gary Schreiber, CWS VI
The Purolite Co.

 

[bimr]

The whitish stuff is calcium carbonate. Calcium carbonate is the only mineral that will precipitate out at the temperature that you describe.

There is nothing in the information that you have presented that will cause dry skin.

"Most of us experience dry and itchy skin from time to time, but you should seek medical attention if discomfort becomes severe," says Dr. Lauren Sternberg, a dermatologist at NewYork-Presbyterian Hospital/Weill Cornell Medical Center. "The best thing you can do to relieve the itch is to moisturize your skin because, unfortunately, you can't do anything about the weather."

"Remember, dry skin is due to lack of water. Apply moisturizers immediately after bathing or showering, while your skin is still wet to trap water in the skin," notes Dr. Sternberg.

She suggests the following tips to turn your skin from alligator into suede:

-- Moisturize daily. Cream moisturizers are better than lotions for normal to dry skin. People with sensitive skin should choose a moisturizer without fragrance or lanolin.

-- Cleanse your skin, but don't overdo it. It is enough to wash your face, hands, feet, and between the folds of your skin once a day. The trunk, arms, and legs can be rinsed daily, but it is not necessary to use soap or cleanser on these areas every day. Too much cleansing removes the skin's natural moisturizers.

-- Limit the use of hot water and soap. If you have "winter itch," take short lukewarm showers or baths with a non-irritating, non-detergent-based cleanser. Immediately afterward, apply a "water-in-oil" -- type moisturizer. Gently pat skin dry.

http://www.medicalnewstoday.com/medicalnews.php?newsid=48942

 

[GarySCWSVI]

I agree with bimr on the likely CaCO3 precipitate. From the limited analysis provided the water has enough "stuff" to cause the white precipitate. I would expect it to be towards the "creamy" or light yellowish color.

For the "itching skin" after bathing, I believe that is caused by the residue of the combination of water minerals and bath soap, in the water conditioning industry called "Scud". Some complain of itching and some complain of dry skin. It may not be dry skin but it does feel like that. Usually corrected by water softening. Not pitching soft water here. Just 35 years of experience in the industry.


Gary Schreiber, CWS VI
The Purolite Co.

 

[hamlton]

Thanks Gary, its creamish to yellowish as you rightly say.