Question

04-9 (ML 6.12) A pristine stream flowing at 100 cubic feet per second (cfs) in the Rocky Mountains contains 5 mg/L of suspended solids (SS). During the spring, ice melt conveys an additional 250 mg/L of TSS at a rate of 20 cfs into the stream. Determine the concentration of TSS in the stream during the spring. (Hint: Treat the ice melt as a secondary stream added to the first.) Answer: 46 mg/L

Answer 1

Answer:

$C_{mix} = 45.833 mg/l$

Explanation:

Give data:

flow rate of stream is $Q_1 100 cfs$

concentration of suspended solids $SS_1 5 mg/L$

During spring time,

concentration of TSS = $SS_2 = 250 mg/l$

flow rate of stream $Q_2= 20 cfs$

we know that, concentration of mix is given as

$C_{mix} = \frac{Q_1 SS_1 +  Q_2 SS_2}{Q_1 +Q_2}$

$C_{mix} = \frac{100\times 5 + 20\times 250}{100+20}$

$C_{mix} = 45.833 mg/l$