please prived sulution for each A waste stream containing a

please prived sulution for each

A waste stream containing a conservative pollutant is released in a river with dissolved oxygen of 8.5 mg/L and flow rate of 50 m³/s. The dissolved oxygen of the waste stream is 3 mg/L and flow rate is 3 m³/s. What will be the resulting dissolved oxygen at the meeting point?

a) Insufficient data           b) 5.27 mg/L                 c) 8.18 mg/L                 d) 3.27 mg/L

An industrial treatment process uses activated carbon to remove color from the water. The color is reduced as a first-order reaction in a batch system. If the rate constant is 0.35 d^-1 how long will it take to remove 90% color.

b) 6.58 days                      b) 7.28 days                  c) 13.16 days                d) 140 hours

Which instrument works on the principle of “scattering of light” for the measurement of turbidity?

a) Spectrometer      b) Optimeter                c) Tinometer                d) Nephelometer

The hardness of water is greater than 1000 mg/L as CaCO₃. Such water will cause increase in consumption of:

a) Toothpaste       b)Soap              c)Cold beverage                       d) Food

BOD3: What does the number 3 indicates?

a) Dilution ratio   b) days             c) temperature            d) microorganism

Solution

(1) Answer:- (c ) 8.18 mg/l

Solution:-

L₀ = (Q_wL_w + Q_rL_r)/(Q_w + Q_r)

L₀ = (3 *3 + 50* 8.5)/(3 + 50)

L₀ = 434/53

L₀ = 8.188 mg/l

(2) Answer:- (a) 6.58 days

Solution:-

ln(C₀/C) = k *t

ln(C₀/(0.1C₀)) = 0.35 *t

ln(1/0.1) = 0.35 t

t = 6.58 days   

(3) Answer:- (d) Nephelometer

(4) Answer:- (b) Soap

(5) Answer :- (b) Days