Recent questions and answers in Environmental Engineering

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Made Easy Gate Previous year Questions
If we have 3 samples Initial DO. Final DO. Volume 1. 9.2 6.9 5 2. 9.1 4.4 10 3. 8.4 0 50 Do we need to consider last sample for finding average BOD?

Don6 asked in Water and Waste Water Quality and Treatment May 11, 2021

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GATE Civil 2021 Set 2 | Question: 14
Determine the correctness or otherwise of the following Assertion $\text{[a]}$ and the Reason $\text{[r]}$. $\text{Assertion [a]}$: One of the best ways to reduce the amount of solid wastes is to reduce the consumption of raw materials. $\text{Reason [r]}$: Solid ... Both $\text{[a]}$ and $\text{[r]}$ are false $\text{[a]}$ is true but $\text{[r]}$ is false

go_editor asked in Municipal Solid Wastes Mar 1, 2021

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3

GATE Civil 2021 Set 2 | Question: 15
The hardness of a water sample is measured directly by titration with $\text{0.01 M}$ solution of ethylenediamine tetraacetic acid $\text{(EDTA)}$ using eriochrome black $\text{T (EBT)}$ as an indicator. The $\text{EBT}$ reacts ... colour of the solution changes from blue-green to reddish brown blue to colourless reddish brown to pinkish yellow Wine red to blue

go_editor asked in Water and Waste Water Quality and Treatment Mar 1, 2021

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GATE Civil 2021 Set 2 | Question: 17
Which of the following statement$\text{(s)}$ is/are correct? Increased levels of carbon monoxide in the indoor environment result in the formation of carboxyhemoglobin and the long term exposure becomes a cause of cardiovascular diseases ... in the indoor environment will result in the formation of photochemical smog which is a cause of cardiovascular diseases

go_editor asked in Air Pollution Mar 1, 2021

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GATE Civil 2021 Set 2 | Question: 32
Read the statements given below. Value of the wind profile exponent for the 'very unstable' atmosphere is smaller than the wind profile exponent for the 'neutral' atmosphere. Downwind concentration of air pollutants due to an elevated point source will be inversely ... is False and $\text{iii}$ is False $\text{iii}$ is False and $\text{iv}$ is False

go_editor asked in Air Pollution Mar 1, 2021

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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 $\text{BOD}$ of the influent, which enters into $\text{ASP}$ ... underflow volume (in $m^{3}$/day, $\textit{round off to one decimal place}$) of sludge wastage is _______________________

go_editor asked in Water and Waste Water Quality and Treatment Mar 1, 2021

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7

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 velocity of the particles is estimated as $\text{2.5 cm/s}$. The ... the chamber (in $\text{m}, \textit{in integer}$) to remove $\text{0.25 mm}$ particles completely is ____________________

go_editor asked in Municipal Solid Wastes Mar 1, 2021

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GATE Civil 2021 Set 1 | Question: 11
Which one of the following statements is correct? Pyrolysis is an endothermic process, which takes place in the absence of oxygen Pyrolysis is an exothermic process, which takes place in the absence of oxygen Combustion is an endothermic ... takes place in the abundance of oxygen Combustion is an exothermic process, which takes place in the absence of oxygen

Arjun asked in Municipal Solid Wastes Feb 20, 2021

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GATE Civil 2021 Set 1 | Question: 12
Which one of the following is correct? The partially treated effluent from a food processing industry, containing high concentration of biodegradable organics, is being discharged into a flowing river at a point $\text{P}$. If the rate of ... $1$ A young lake characterized by low nutrient content and low plant productivity is called $\textit{eutrophic lake}$

Arjun asked in Water and Waste Water Quality and Treatment Feb 20, 2021

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GATE Civil 2021 Set 1 | Question: 13
The liquid forms of particulate air pollutants are dust and mist mist and spray smoke and spray fly ash and fumes

Arjun asked in Air Pollution Feb 20, 2021

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GATE Civil 2021 Set 1 | Question: 28
A $50$ $\text{mL}$ sample of industrial wastewater is taken into a silica crucible. The empty weight of the crucible is $54.352$ $\text{g}$. The crucible with the sample is dried in a hot air oven at $104\;^{\circ}C$ till a constant weight of ... volatile solids is _____________________ $\text{15540 mg/L}$ $\text{8620 mg/L}$ $\text{6920 mg/L}$ $\text{1700 mg/L}$

Arjun asked in Water and Waste Water Quality and Treatment Feb 20, 2021

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GATE Civil 2021 Set 1 | Question: 33
A water sample is analyzed for coliform organisms by the multiple-tube fermentation method. The results of confirmed test are as follows: $\begin{array}{|cl|cI|cI|}\hline &\textbf{Sample size $ ... $110$ The $\text{MPN}$ of coliform organisms per $\text{100 mL}$ is $1100000$ $110000$ $1100$ $110$

Arjun asked in Water and Waste Water Quality and Treatment Feb 20, 2021

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GATE Civil 2021 Set 1 | Question: 34
Ammonia nitrogen is present in a given wastewater sample as the ammonium ion $\text({NH}_{4}$^{+})$ and ammonia $\text({NH}_{3})$. If $ ... _{3}$ will be found in equal measures At $\text{pH}$ $7.0$, $\text{NH}_{4}$^{+}$ will be predominant

Arjun asked in Water and Waste Water Quality and Treatment Feb 20, 2021

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GATE Civil 2021 Set 1 | Question: 51
A baghouse filter has to treat $12\text{ m}^3/\text{s}$ of waste gas continuously. The baghouse is to be divided into $5$ ... $5 \text{ m}$ in length. The total number of bags ($\textit{in integer}$) required in the baghouse is __________________

Arjun asked in Air Pollution Feb 20, 2021

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GATE Civil 2021 Set 1 | Question: 52
A secondary clarifier handles a total flow of $9600 \text{ m}^3\text{/d}$ from the aeration tank of a conventional activated-sludge treatment system. The concentration of solids in the flow from the aeration tank is $3000\text{ mg/L}$. ... . The surface area of the designed clarifier for thickening (in $\text{m}^2$, $\textit{in integer}$) is ___________________

Arjun asked in Water and Waste Water Quality and Treatment Feb 20, 2021

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16

GATE2017 CE-1: 55
The wastewater having an organic concentration of $54$ mg/l is flowing at a steady rate of $0.8 \: m^3/day$ through a detention tank of dimensions $2m \times 4 m \times 2 m$. If the contents of the tank are well mixed and the decay constant $0.1$ per day, the outlet concentration (in mg/l, up to one decimal place) is _________

Vipin6419 answered in Water and Waste Water Quality and Treatment Jun 28, 2020

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17

GATE2020-CE-1-25
A river has a flow of $1000$ million litres per day (MLD), $BOD_5$ of $5\:mg/litre$ and Dissolved Oxygen (DO) level of $8\:mg/litre$ before receiving the wastewater discharge at a location. For the existing environmental conditions, the saturation ... complete mixing of wastewater and river water, the immediate DO deficit (in $mg/litre$ round off to two decimal places), is ______.

go_editor asked in Water and Waste Water Quality and Treatment Feb 28, 2020

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18

GATE2020-CE-1-53
A gaseous chemical has a concentration of $41.6\:\mu mol/m^3$ in air at $1$ atm pressure and temperature $293\:K$. The universal gas constant $R$ is $82.05\times10^{-6}\;(m^3\:atm)/(mol\:K)$. Assuming that ideal gas law is valid , the concentration of the gaseous chemical (in ppm, round off to one decimal place), is ______.

go_editor asked in Air Pollution Feb 28, 2020

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19

GATE2020-CE-1-54
A stream with a flow rate of $5\:m^3/s$ is having an ultimate BOD of $30\:mg/litre$. A wastewater discharge of $0.20\:m^3/s$ having $BOD_5\:\text{of}\:500\:mg/litre$ joins the stream at a location and instantaneously gets mixed up completely. The ... $e$). The BOD (in mg/litre, round off to two decimal places) remaining at $3\:km$ downstream from the mixing location, is __________

go_editor asked in Water and Waste Water Quality and Treatment Feb 28, 2020

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20

GATE2020 CE-2-16
The relationship between oxygen consumption and equivalent biodegradable organic removal (i.e.,BOD) in a closed container with respect to time is shown in the figure Assume that the rate of oxygen consumption is directly proportional to the amount of degradable organic matter and is expressed as ... is $BOD_5 = L_5$ $BOD_t = L_0-L_t$ $L_0 = L_te^{-kt}$ $L_t = L_0(1-e^{-kt})$

go_editor asked in Water and Waste Water Quality and Treatment Feb 13, 2020

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21

GATE2020 CE-2-17
A gas contains two types of suspended particles having average sizes of $2\: \mu m$ and $50\: \mu m$. Amongst the options given below, the most suitable pollution control strategy for removal of these ... bag filter electrostatic precipitator followed by venturi scrubber electrostatic precipitator followed by cyclonic separator bag filter followed by electrostatic precipitator

go_editor asked in Air Pollution Feb 13, 2020

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22

GATE2020 CE-2-52
The ion product of water $(pK_w)$ is $14$. If a rain water sample has a $pH$ of $5.6$, the concentration of $OH^-$ in the sample (in $10^{-9}\: \text{mol/litre}$, round off to one decimal place), is ________.

go_editor asked in Water and Waste Water Quality and Treatment Feb 13, 2020

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23

GATE2020 CE-2-53
A waste to energy plant burns dry solid waste of composition: Carbon $= 35\%$, Oxygen $= 26\%$ , Hydrogen $= 10\%$, Sulphur $= 6\%$, Nitrogen $= 3\%$ and Inerts $= 20\%.$ Burning rate is $1000\: $ tonnes/d. Oxygen in air ... The stoichiometric (theoretical) amount of air ( in tonnes/d, round off to the nearest integer) required for complete burning of this waste is ________.

go_editor asked in Municipal Solid Wastes Feb 13, 2020

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24

GATE2020 CE-2-54
A sample of water contains an organic compound $C_8H_{16}O_8$ at a concentration of $10^{-3}\: \text{mol/litre}$. Given that the atomic weight of $C = 12\: \text{g/mol}, H = 1\: \text{g/mol}$, and $O = 16\: \text{g/mol}$, the theoretical oxygen demand of water (in $g$ of $O_2$ per litre, round off to two decimal places), is ________.

go_editor asked in Water and Waste Water Quality and Treatment Feb 13, 2020

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25

GATE2017 CE-2-8
As per Noise Pollution (Regulation and Control) Rules $2000$ of India, the day time noise limit for a residential zone, expressed in dB(A)L$_{eq}$, is $55$ $65$ $75$ $85$

gatecse asked in Noise Pollution Aug 7, 2019

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26

GATE2017 CE-2-9
Following observations have ben made for the elevation and temperature to ascertain the stability of the atmosphere: $\begin{array}{|c|c|} \hline \text{Elevation (in m) } & \text{Temperature (in }^{\circ} \text{C)} \\ \hline 10 & 15.5 \\ \hline 60 & 15.0 \\ \hline 130 & 14.3 \\ \hline \end{array}$ The atmosphere is classified as Stable Unstable Neutral Inverse

gatecse asked in Air Pollution Aug 7, 2019

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27

GATE2017 CE-2-10
The most important type of species involved in the degradation of organic matter in the case of activated sludge process is autotrophs heterotrophs prototrophs photo-autotrophs

gatecse asked in Water and Waste Water Quality and Treatment Aug 7, 2019

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28

GATE2017 CE-2-50
The composition of a municipal solid waste sample is given below: ... The difference between the energy content of the waste sample calculated on dry basis and as-discarded basis (in kJ/kg) would be _______

gatecse asked in Municipal Solid Wastes Aug 7, 2019

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29

GATE2017 CE-2-51
For a given water sample, the ratio between BOD$_{\text{5-day, 20}^{\circ} C}$ and the ultimate BOD is $0.68$. The value of the reaction rate constant $k$ (on base $e$) (in day$^{-1}$, up to two decimal places) is ________

gatecse asked in Water and Waste Water Quality and Treatment Aug 7, 2019

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30

GATE2017 CE-2-52
A municipal corporation is required to treat $1000 \: m^3/day$ of water. It is found that an overflow rate of $20 m/day$ will produce a satisfactory removal of the discrete suspended particles at a depth of $3 m$. The diameter (in meters, round to the nearest integer) of a circular settling tank designed for the removal of these particles would be ___________

gatecse asked in Municipal Solid Wastes Aug 7, 2019

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31

GATE2019 CE-1: 18
Which one of the following is a secondary pollutant? Ozone Carbon Monoxide Hydrocarbon Volatile Organic Carbon (VOC)

Arjun asked in Air Pollution Feb 14, 2019

by Arjun

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32

GATE2019 CE-1: 34
Sedimentation basin in a water treatment plant is designed for a flow rate of $0.2 \: m^3/s$. The basin is rectangular with a length of $32 \: m$, width of $8 \:m $, and depth of $4 \: m$. Assume that the settling velocity of these particles is governed by ... diameter $25 \mu m$ (spherical and uniform), the removal efficiency of these particles is $51 \%$ $65 \%$ $78 \%$ $100 \%$

Arjun asked in Water and Waste Water Quality and Treatment Feb 14, 2019

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33

GATE2019 CE-1: 40
A sample of air analysed at $0^{\circ} C$ and $1 \: atm$ pressure is reported to contain $0.02 \: ppm$ (parts per million) of $NO_2$. Assume the gram molecular mass of $NO_2$ as $46$ and its volume at $0^{\circ} C$ and $1 \: atm$ pressure as $22.4$ litres per mole. The equivalent $NO_2$ concentration (in microgram per cubic meter, round off to $2$ decimal places) would be ________

Arjun asked in Air Pollution Feb 14, 2019

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34

GATE2019 CE-1: 42
A wastewater is to be disinfected with $35 \: mg/L$ of chlorine to obtain $99 \%$ kill of micro-organisms. The number of micro-organisms remaining alive $(N_t)$ at time $t$, is modelled by $N_t=N_o e^{-kt}$, where $N_o$ is number of micro-microorganisms at $t=0$, ... $1.0 \: m$, respectively, the length of the tank (in $m$, round off to $2$ decimal places) is ________

Arjun asked in Water and Waste Water Quality and Treatment Feb 14, 2019

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35

GATE2019 CE-2: 9
Which one of the following options contains ONLY primary air pollutants? Hydrocarbons and nitrogen oxides Hydrocarbons and ozone Ozone and peroxyacetyl nitrate Nitrogen oxides and peroxyacetyl nitrate

Arjun asked in Air Pollution Feb 12, 2019

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36

GATE2019 CE-2: 10
Analysis of a water sample revealed that the sample contains the following species. $CO_3^{2-}, Na^+, H^+, PO_4^{3-}, Al^{3+}, H_2CO_3, Cl^-, Ca^{2+}, Mg^{2+}, HCO_3^-, Fe^{2+}, OH^-$ ... $CO_3^{2-}, H^+, H_2CO_3, HCO_3^-$ $CO_3^{2-}, H_2CO_3, HCO_3^-, OH^-$ $H^+, H_2CO_3, HCO_3^-, OH^-$

Arjun asked in Water and Waste Water Quality and Treatment Feb 12, 2019

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37

GATE2019 CE-2: 32
Chlorine is used as the disinfectant in a municipal water treatment plant. It achieves $50$ percent of disinfection efficiency measured in terms of killing the indicator microorganisms (E-Coli) in $3$ minutes. The minimum time required to achieve $99$ percent disinfection efficiency would be $9.93$ minutes $11.93$ minutes $19.93$ minutes $21.93$ minutes

Arjun asked in Water and Waste Water Quality and Treatment Feb 12, 2019

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38

GATE2019 CE-2: 40
A water treatment plant treats $6000 \: m^3$ of water per day. As a part of the treatment process, discrete particles are required to be settled in a clarifier. A column test indicates that an overflow rate of $1.5 \: m$ per hour would produce the desired removal of ... of $3.0 \:m$. The volume of the required clarifier, (in $m^3$, round off to $1$ decimal place) would be ______

Arjun asked in Water and Waste Water Quality and Treatment Feb 12, 2019

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39

GATE2019 CE-2: 41
Raw municipal solid waste (MSW) collected from a city contains $70 \%$ decomposable material that can be converted to methane. The water content of the decomposable material is $35\%$. An elemental analysis of the decomposable material yields the following mass percent. ... The mass of methane produced (in grams, round off to $1$ decimal place) per kg of raw MSW will be _________

Arjun asked in Municipal Solid Wastes Feb 12, 2019

by Arjun

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40

GATE2019 CE-2: 42
Consider the reactor shown in the figure. The flow rate through the reactor is $Q \: m^3/h$. The concentrations (in $mg/L$) of a compound in the influent and effluent are $C_0$ and $C$, respectively. The compound is degraded in the reactor following the first order ... $L_{\text{CMFR}}/L_{\text{PFR}}$ (round off to $2$ decimal places) is ____________

Arjun asked in Water and Waste Water Quality and Treatment Feb 12, 2019

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