Drinking-water Treatment and Distribution - Water & Wastewater Treatment and Management - Environmental Science & Engineering Previous Year Questions

1

2024 · Environmental Science & Engineering · Water & Wastewater Treatment and Management · Drinking-water Treatment and Distribution

Environmental Science & Engineering (ES) 2024

The processes of removal of particles in a rapid sand filter with their description is given in the table.

Process	Description
(i) Straining	P: Removes only particles in the water large enough to get caught in the pores of the filter
(ii) Sedimentation	Q: Larger and heavier particles do not follow the fluid streamline around the sand grain and settle on the grain
(iii) Interception	R: Particles that do follow the streamline, but are too large and are caught because they brush up against the sand grains
(iv) Diffusion	S: Very small particles are experiencing Brownian motion and may collide with the sand grains by chance

Select the correct match.

A

i- S; ii-P; iii-Q; iv-R

B

i-Q; ii-R; iii-S; iv-P

C

i-R; ii- S; iii- P; iv-Q

D

i-P; ii-Q; iii-R; iv-S

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2

2025 · Environmental Science & Engineering · Water & Wastewater Treatment and Management · Drinking-water Treatment and Distribution

Environmental Science & Engineering (ES) 2025

Choose the correct option(s) for removing solids from water.

A

chlorination

B

coagulation-flocculation-sedimentation followed by slow sand filtration

C

chlorination followed by aeration

D

slow sand filtration

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3

2021 · Environmental Science & Engineering · Water & Wastewater Treatment and Management · Drinking-water Treatment and Distribution

Environmental Science & Engineering (ES) 2021

Chlorine is most effective as a water disinfectant at a pH of __________.

A

6

B

8

C

10

D

12

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4

2022 · Environmental Science & Engineering · Water & Wastewater Treatment and Management · Drinking-water Treatment and Distribution

Environmental Science & Engineering (ES) 2022

Centrifugal pumps with suction pipe (shown by solid arrow) and delivery pipe (shown by dotted arrow) are shown in the figures. Choose the option that gives the correct connection

A

B

C

D

Page 14

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5

2022 · Environmental Science & Engineering · Water & Wastewater Treatment and Management · Drinking-water Treatment and Distribution

Environmental Science & Engineering (ES) 2022

Carbon dioxide is used in recarbonation process. A solution has 1 mole/L supersaturated calcium carbonate. Estimated amount of carbon dioxide (in grams) needed to completely convert calcium carbonate to calcium ions in 1 litre solution is

A

44.000 gram

B

0.044 gram

C

40.000 gram

D

0.040 gram

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6

2022 · Environmental Science & Engineering · Water & Wastewater Treatment and Management · Drinking-water Treatment and Distribution

Environmental Science & Engineering (ES) 2022

A river water sample has pH of 4 and suspended solids concentration of 100 mg/L. If, alum is chosen as a coagulant, what will be the coagulation mechanism?

A

Ionic layer compression only

B

Sweep coagulation and Polymer bridging

C

Polymer bridging only

D

Charge neutralization, surface adsorption, ionic layer compression

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7

2022 · Environmental Science & Engineering · Water & Wastewater Treatment and Management · Drinking-water Treatment and Distribution

Environmental Science & Engineering (ES) 2022

Clean water is passed through a bed of uniform spherical sand at a filtration velocity of 0.002 m/sec. The sand grains are 0.4 mm in diameter and have a specific gravity of 2.65. Bed depth is 0.67 m and porosity (\( \eta \)) is 0.35. Given, water density = 998.2 kg/m³; water dynamic viscosity = \( 1.002 \times 10^{-3} \) Pa.s. Friction factor (\( f \)) is given as: \( f = 1.75 + 150 \times (1 - \eta)/Re \), where Re is Reynolds number. The headloss (in m, rounded off to three decimal places) calculated using the Carmen-Kozney equation is __________.

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8

2023 · Environmental Science & Engineering · Water & Wastewater Treatment and Management · Drinking-water Treatment and Distribution

Environmental Science & Engineering (ES) 2023

A flask (100 ml volume) has wastewater, which has 0.12 mg/L geosmin. Activated carbon is added in this flask for adsorbing geosmin as per the Freundlich isotherm model (Q = 2.6C^0.73 where Q is mg adsorbate/mg adsorbent and C is the equilibrium concentration in mg/L). Activated carbon to be added in this flask for getting final remaining geosmin concentration of 0.05 mg/L would be __________ (in mg/L, rounded off to three decimal places).

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9

2026 · Environmental Science & Engineering · Water & Wastewater Treatment and Management · Drinking-water Treatment and Distribution

Environmental Science & Engineering (ES) 2026

Which of the following options is/are TRUE about reverse osmosis process?

A

Reverse osmosis is used as a pretreatment for microfiltration process.

B

Ultrafiltration is used as a pretreatment for reverse osmosis process.

C

Membrane fouling occurs in microfiltration and reverse osmosis processes.

D

Concentration polarization does not occur in reverse osmosis process.

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10

2026 · Environmental Science & Engineering · Water & Wastewater Treatment and Management · Drinking-water Treatment and Distribution

Environmental Science & Engineering (ES) 2026

Which of the following options is/are TRUE about coagulation-flocculation process?

A

Collision of colloidal particles due to their Brownian motion results in orthokinetic flocculation.

B

Collision of colloidal particles due to the external mixing of bulk medium results only in perikinetic flocculation.

C

In an electric double layer model of a colloidal particle, Stern layer is more compact than the diffuse layer.

D

The zeta potential is also called Stern potential.

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