1
GATE CE 2025 Set 1
MCQ (More than One Correct Answer)
+2
-0
A facultative pond system is employed for wastewater treatment. Which of the following statements is/are true:
A
The dissolved oxygen concentration will be high during daytime compared to nighttime
B
The pH will be high during daytime compared to night-time
C
The dissolved oxygen concentration will be low during daytime compared to nighttime
D
The pH will be low during daytime compared to night-time
2
GATE CE 2023 Set 1
MCQ (Single Correct Answer)
+2
-0.66

In the following table, identify the correct set of associations between the entries in Column - 1 and Column-2.

Column-1 Column-2
P: Reverse Osmosis III: Concentration Polarization
Q: Trickling Filter I: Ponding
R: Coagulation IV: Charge Neutralization
S: Adsorption II: Freundlich Isotherm
A
P - II, Q - I, S - III
B
Q - III, R - II, S - IV
C
P - IV, R - I, S - II
D
P - III, Q - I, R - IV
3
GATE CE 2023 Set 1
Numerical
+2
-0
The wastewater inflow to an activated sludge plant is 0.5 m3/s, and the plant is to be operated with a food to microorganism ratio of 0.2 mg/mg-d. The concentration of influent biodegradable organic matter of the wastewater to the plant (after primary settling) is 150 mg/L, and the mixed liquor volatile suspended solids concentration to be maintained in the plant is 2000 mg/L. Assuming that complete removal of biodegradable organic matter in the tank, the volume of aeration tank (in m3, in integer) required for the plant is _________.
Your input ____
4
GATE CE 2022 Set 2
MCQ (Single Correct Answer)
+2
-0.67

In a city, the chemical formula of biodegradable fraction of municipal solid waste (MSW) is C100H250O80N. The waste has to be treated by forced-aeration composting process for which air requirement has to be estimated.

Assume oxygen in air (by weight) = 23% and density of air = 1.3 kg/m3. Atomic mass : C = 12, H = 1, O = 16, N = 14.

C and H are oxidized completely whereas N is converted only into NH3 during oxidation.

For oxidative degradation of 1 tonne of the waste, the required theoretical volume of air (in m3/tonne) will be (round off the nearest integer)

A
1092
B
4749
C
1418
D
8025
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