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Recent questions and answers in Environmental Engineering

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GATE Civil 2026 Set 2 | Question: 17
Column $\text{I}$ presents common air pollutants, and column $\text{II}$ presents treatment technologies commonly employed to control air pollutants.\[\begin{array}{|c|l|...
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GATE Civil 2026 Set 2 | Question: 18
One-third of the solid matter in a sludge containing $90 \%$ water is composed of fixed mineral solids with specific gravity $2.5$, and two-third is composed of volatile ...
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GATE Civil 2026 Set 2 | Question: 19
The grown algae are useful in the operation ofoxidation pond.slow sand filter.cyclone separator.septic tank.
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GATE Civil 2026 Set 2 | Question: 32
The $2.4$ ml of raw sewage is diluted to $240$ ml. The Dissolved Oxygen (DO) of the diluted sample at the beginning of Biochemical Oxygen Demand (BOD) test was $8 \mathrm...
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GATE Civil 2026 Set 2 | Question: 53
The analysis of major cations and anions in a water sample collected from a city's water supply is given below. Ions present in minor concentrations are not given.\[\begi...
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GATE Civil 2026 Set 2 | Question: 54
Anaerobic bacteria are being utilized for the destruction of biodegradable organic content of wastewater measured in terms of Chemical Oxygen Demand (COD). The yield coef...
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GATE Civil 2026 Set 2 | Question: 55
In an industry, a cyclone collector with $80 \%$ efficiency is installed for air purification, followed by an electrostatic precipitator with $50 \%$ efficiency. The conc...
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GATE Civil 2026 Set 1 | Question: 11
A rapid sand filter bed of depth $0.8$ m has $40 \%$ porosity during service cycle. It is recommended that during backwash operation, the expanded filter bed should have ...
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GATE Civil 2026 Set 1 | Question: 12
The settling velocity of inorganic particles in the sedimentation tank of a water treatment plant is governed byDarcy's lawStokes' lawDupuit's lawBernoulli's law
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GATE Civil 2026 Set 1 | Question: 15
Which of the following components is/are NOT removed in the secondary treatment of sewage?Suspended settleable organic solidsColloids including dissolved organic matterPa...
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GATE Civil 2026 Set 1 | Question: 34
The average sewage from a city is $90$ million litres per day and the average $5$-day Biochemical Oxygen Demand ($\text{BOD5}$) is $300 ~\mathrm{mg} / \mathrm{l}$. Averag...
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GATE Civil 2026 Set 1 | Question: 53
An Activated Sludge Process $\text{(ASP)}$ has an inlet wastewater flowrate of $20000 \mathrm{~m}^{3} /$ day with a Biochemical Oxygen Demand $\text{(BOD)}$ concentration...
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GATE Civil 2026 Set 1 | Question: 55
The maximum demand at a water purification plant has been estimated as $12$ million litres per day. For the raw supplies, a rectangular sedimentation tank is to be design...
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Municipal solid waste
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GATE Civil 2025 Set 1 | Question: 11
​​​​​Fecal Coliform (FC) concentration in river water was measured as $10780 \: \: \mathrm{cfu} / 100 \mathrm{ ml}$ . The FC concentration after the conventional water tr...
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GATE Civil 2022 Set 1 | Question: 17
Which of the following process(es) can be used for conversion of salt water into fresh water?MicrofiltrationElectrodialysisUltrafiltrationReverse osmosis
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GATE Civil 2022 Set 1 | Question: 32
Henry's law constant for transferring $O_{2}$ from air into water, at room temperature, is $1.3 \dfrac{\text{mmol}}{\text{liter-atm}}$. Given that the partial pressure of...
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GATE Civil 2022 Set 1 | Question: 33
In a water sample, the concentrations of $Ca^{2+}, Mg^{2+}$ and $\text{HCO}_{3}^{-}$ are $100$ $\text{mg/L}$, $36$ $\text{mg/L}$ and $122$ $\text{mg/L}$, respectively. Th...
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GATE Civil 2022 Set 1 | Question: 50
A $2\%$ sewage sample (in distilled water) was incubated for $3$ days at $27^{\circ}C$ temperature. After incubation, a dissolved oxygen depletion of $10\:mg/L$ was recor...
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GATE Civil 2022 Set 1 | Question: 51
A water treatment plant has a sedimentation basin of depth $3\:m$, width $5\:m$, and length $40\:m$. The water inflow rate is $500\:m^{3}/h$. The removal fraction of part...
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GATE Civil 2021 Set 1 | Question: 13
The liquid forms of particulate air pollutants aredust and mistmist and spraysmoke and sprayfly ash and fumes
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GATE Civil 2025 Set 2 | Question: 51
The analyses results of a water sample are given below. The non-carbonate hardness of the water (in $\mathrm{mg} / \mathrm{L}$ ) as $\mathrm{CaCO}_{3}$ is $\_\_\_\_\_\_\_...
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GATE Civil 2025 Set 2 | Question: 52
A community generates $1$ million litres/day (MLD) of wastewater. This wastewater is treated using activated sludge process (ASP). The working volume of the aeration tank...
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GATE Civil 2021 Set 2 | Question: 51
An activated sludge process $\text{(ASP)}$ is designed for secondary treatment of $7500\:m^{3}/$day of municipal wastewater. After primary clarifier, the ultimate $\text{...
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GATE Civil 2021 Set 2 | Question: 52
A grit chamber of rectangular cross-section is to be designed to remove particles with diameter of $\text{0.25 mm}$ and specific gravity of $2.70$. The terminal settling ...
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GATE Civil 2024 Set 1 | Question: 21
The primary air pollutant(s) is/areSulfur dioxideLeadOzoneSulphuric acid
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GATE Civil 2024 Set 1 | Question: 11
​​​​​The following table gives various components of Municipal Solid Waste (MSW) and a list of treatment/separation techniques.\begin{array}{|l|l|}\hline \text{Component ...
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GATE Civil 2025 Set 1 | Question: 35
​​​​​A facultative pond system is employed for wastewater treatment. Which of the following statements is/are true:The dissolved oxygen concentration will be high during ...
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GATE Civil 2024 Set 2 | Question: 16
Which one of the following products is NOT obtained in anaerobic decomposition of glucose?$\mathrm{CO}_{2}$$\mathrm{CH}_{4}$$\mathrm{H}_{2} \mathrm{~S}$$\mathrm{H}_{2} \m...
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GATE Civil 2023 Set 2 | Question: 35
Match the following air pollutants with the most appropriate adverse health effects:$$\begin{array}{|l|l|}\hline \textbf{Air pollutant} & \textbf{Health effect to human a...
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GATE Civil 2025 Set 1 | Question: 22
​​​​​​Aeration is employed as a treatment option for the removal of several pollutants from contaminated water.Identify the pollutant(s), where aeration is employed as a ...
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GATE Civil 2025 Set 1 | Question: 21
​​​​​​The Surface Overflow Rate (SOR) in a rectangular sedimentation tank is $45\: \mathrm{m}^{3} / \mathrm{m}^{2} / \mathrm{d}$. Minimum diameters of spherical inorganic...
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GATE Civil 2024 Set 1 | Question: 51
A water treatment plant treats $25 \mathrm{MLD}$ water with a natural alkalinity of $4.0 \mathrm{mg} / \mathrm{L}$ (as $\mathrm{CaCO}_{3}$ ). It is estimated that, during...
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GATE Civil 2025 Set 2 | Question: 17
Identify the treatment technology/technologies NOT recommended for highly biodegradable organic solid wastes.BiohydrogenationAnaerobic digestionCompostingOpen dumping
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GATE Civil 2024 Set 2 | Question: 15
What is the CORRECT match between the air pollutants and treatment techniques given in the table?\begin{array}{|l|l|}\hline \text{Air pollutants} & \text{Treatment techni...
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GATE Civil 2025 Set 2 | Question: 7
The bacteria mainly responsible for crown corrosion in a sewer is $\_\_\_\_\_\_\_\_\_$Methanogenic bacteriaDenitrifying bacteriaSulphur reducing bacteriaPseudomonas bacte...
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GATE Civil 2025 Set 2 | Question: 24
Free residual chlorine concentration in water was measured to be $2 \mathrm{mg} / 1\left(\right.$ as $\left.\mathrm{Cl}_{2}\right)$. The pH of water is $8.5$. By using th...
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GATE Civil 2025 Set 2 | Question: 39
A compound has a general formula $\mathrm{C}_{\mathrm{a}} \mathrm{H}_{\mathrm{b}} \mathrm{O}_{\mathrm{c}} \mathrm{N}_{\mathrm{d}}$ and molecular weight $187$. A $935 \: \...
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GATE Civil 2025 Set 2 | Question: 53
A settling chamber is used for the removal of discrete particulate matter from air with following conditions. Horizontal velocity of air $=0.2 \mathrm{~m} / \mathrm{s}$; ...
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GATE Civil 2025 Set 1 | Question: 12
​​​​​A hydrocarbon $\left(\mathrm{C}_{\mathrm{n}} \mathrm{H}_{\mathrm{m}}\right)$ is burnt in air $\left(\mathrm{O}_{2}+3.78 \mathrm{~N}_{2}\right)$. The stoichiometric f...
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