Question

Say I have an initial concentration of 10% wastewater (ww) in a bin (1L ww, 9L creek water). So 10 Liters total with a concentration of 10% ww.

I am diluting ww with creek water. I keep pouring 1 liter aliquots of creek water into this bin to further dilute. My trash bin only holds a volume of 50 liters, but I need to keep diluting. If I take out half of the total volume in my bin (to have only 25), but I keep adding 1L, how do I know what my ww concentration is when I add the subsequent 1L of creek water to the mixture?

Answer 1

If you have an initial volume of 10L (9 L of creek water and 1 L of wastewater (WW)), with a concentration of 10% WW. Assuming you still adding creek water to dilute wastewater until you reach a final volume of 25 L. The concentration of wastewater will change. You can use the following formula in order to know the final concentration of wastewater. This case is only considering you have 24 L of creek water and 1 L of WW.

C₁ X V₁=C₂ X V₂

Where:

C₁= Initial concentration

V₁= Initial volume

C₂= Final concentration

V₂= Final volume

You have the following data:

C₁= 10%

V₁= 10 L

V₂= 25 L

C₂= ?

Solving for C₂ we obtained the following concentration:

(10%)x(10L)= (C₂)x (25L)

100 %.L / 25 L = C₂

C₂ = 4%

So your final concentration of WW will be 4%.