GATE Environmental Science and Engineering Practice Quiz

Question 1

In a conventional municipal wastewater treatment plant, the influent has $BOD_5 = 240\,\text{mg/L}$. Primary sedimentation removes $30\%$ of the influent $BOD_5$, and the secondary biological treatment removes $85\%$ of the $BOD_5$ entering it. The final effluent $BOD_5$ is closest to:

Accepted Answer

$25\,\text{mg/L}$

Question 2

For an ideal plug flow reactor used for disinfection, the influent microbial concentration is $N_0$, the effluent concentration is $N$, the first-order inactivation rate constant is $k$, and hydraulic detention time is $t$. Which expression is correct?

Accepted Answer

$\frac{N}{N_0}=e^{-kt}$

Question 3

Which of the following is the primary anthropogenic gas responsible for stratospheric ozone depletion through catalytic chlorine radical reactions?

Accepted Answer

Chlorofluorocarbons such as $CCl_2F_2$

Question 4

A river receives a biodegradable organic waste discharge. According to the classical oxygen sag concept, which statement best describes the critical point downstream of the discharge?

Accepted Answer

It is the location where the rate of deoxygenation equals the rate of reaeration.

Question 5

A baghouse filter treats flue gas containing particulate matter. If the collection efficiency is $99.5\%$ and the inlet particulate concentration is $4.0\,\text{g/m}^3$, the outlet concentration is:

Accepted Answer

$0.020\,\text{g/m}^3$

GATE Environmental Science and Engineering

Practice Quizzes

GATE Environmental Science and Engineering Practice Quiz

BOD and COD Analysis Fundamentals | GATE Environmental Science and Engineering