Polymer @ 0.5% TSS Solution? 2

[kforce]

Help,

I am trying to make sense of calculations for a potable water treatment plant. The following are particulars listed for the plant:

Raw water flow rate = 1,600,000 gpd
Polymer dosing rate = 2 mg/l
Polymer solution = 0.5% TSS solution.
Polymer required = 26.7 lb/day

Without knowing the particulars of the polymer, can anyone tell me how to calculate the flow rate (in gpd) of the the polymer solution?

Thanks for the help.

 

[kenvlach]

Presumably, " Polymer solution = 0.5% TSS solution" means a 0.5 wt% polymer suspension in water.
Thus, need 1/0.5% = 200 times as much of the mixture by wt. So,

26.7 lbs/day x 200 = 5340 lbs/day.
Taking the mixture's density as 8.34 lb/gal,
need 5340/8.34 = 640 GPD of the mixture (0.4446 gpm).

 

[bimr]

Try searching before you post. DocMax just did this for someone else.

DocMax (Chemical)
18 Sep 06 15:54
hi madhusmile

first you will know what is the dilution of polymer.
Polymers are so viscous so it's necessary to make a diluition.
For example if the polymer solution after dilution is 0.5% the math is:


1,600,000 gpd = 252.36 m3/h 2 ppm = 2 g/m3

252.36 m3/h X 2 g/m3 = 504.72 g/h

504.72/0.005 = 100944 g/h = 100.9 kg/h

If the density of solution is 1000 kg/m3:

100.9 kg/h / 1000 kg/m3 = 0.1009 m3/h

the dosing pump will be 0.1009 m3/h = 100.9 l/h = 0.444 gpm or 639.998 gallon/day [US]

2 mg/l / 120 = .0166 lbs/1000 gal

.0166 lbs/1000 gal X 1,600,000 gpd = 26.6 lbs/day polymer

26.6 lbs/day polymer / 0.005 solution strength = 5,333 lbs/day solution

5,333 lbs/day solution / 8.34 lbs/ gal = 639.48 gal/day polymer

 

[kforce]

bimr,

I tried searchig for the topic before posting, but could not find it...for this particular topic, how should I have searched for it?

Thanks!

 

[bimr]

I guess that is a good question. Sometimes it is easier said than done. The search engine is not that easy to use. On this particular post, I remembered it as it was just posted a couple of weeks ago.

http://www.eng-tips.com/viewthread.cfm?qid=165542&page=1

I tried searching for it and could not get it to come up. Unfortunately it has misspelled words that won't search.