Recent questions tagged environmental-engineering

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1

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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2

GATE2017 CE-2-6
Consider a rigid retaining wall with partially submerged cohesionless backfill with a surcharge. Which one of the following diagrams closely represents the Rankine’s active earth pressure distribution against this?

gatecse asked in Foundation Engineering Aug 7, 2019

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3

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

by gatecse

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4

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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5

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

by gatecse

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6

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

by gatecse

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7

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

by gatecse

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8

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

by gatecse

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9

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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10

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

by Arjun

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11

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

by Arjun

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12

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

by Arjun

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13

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

by Arjun

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14

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

by Arjun

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15

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

by Arjun

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16

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

by Arjun

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17

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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18

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

by Arjun

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19

GATE2016-2-18
A water supply board is responsible for treating $1500 \:m^3/day$ of water. A settling column analysis indicates that an overflow rate of $20 \: m/day$ will produce satisfactory removal for a depth of $3.1 \: m$. It is decided to have two circular settling tanks in parallel. The required diameter (expressed in $m$) of the settling tank is __________

Milicevic3306 asked in Water and Waste Water Quality and Treatment Mar 28, 2018

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20

GATE2016-2-19
The hardness of a ground water sample was found to be $420 \: mg/L$ as $CaCO_3$. A softener containing ion exchange resins was installed to reduce the total hardness to $75 \: mg/L$ as $CaCO_3$ before supplying to $4$ households. Each household gets treated water at ... $100\%$, the bypass flow rate (expressed in $L/day$) is _________

Milicevic3306 asked in Water and Waste Water Quality and Treatment Mar 28, 2018

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21

GATE2016-2-20
The sound pressure (expressed in $\mu P a$) of the faintest sound that a normal healthy individual can hear is $0.2$ $2$ $20$ $55$

Milicevic3306 asked in Noise Pollution Mar 28, 2018

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22

GATE2016-2-50
A sample of water has been analyzed for common ions and results are presented in the form of a bar diagram as shown. The non-carbonate hardness (expressed in mg/L as $CaCO_3$) of the sample is $40$ $165$ $195$ $205$

Milicevic3306 asked in Water and Waste Water Quality and Treatment Mar 28, 2018

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23

GATE2016-2-51
A noise meter located at a distance of $30 \: m$ from a point source recorded $74 \: dB$. The reading at a distance of $60 \: m$ from the point source would be __________

Milicevic3306 asked in Noise Pollution Mar 28, 2018

by Milicevic3306

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24

GATE2016-2-52
For a wastewater sample, the three-day biochemical oxygen demand at incubation temperature of $20^{\circ}C$ (BOD$_{\text{3day}, 20^{\circ}C}$) is estimated as $200 mg/L$ ... in mg/L) of the wastewater at incubation temperature of $20^{\circ}C$ (BOD$_{\text{5day}, 20^{\circ}C}$) would be ________

Milicevic3306 asked in Water and Waste Water Quality and Treatment Mar 28, 2018

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11.9k points

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25

GATE2016-1-17
Pre-cursors to photochemical oxidants are $NO_X, \: VOC$s and sunlight $SO_2, \: CO_2$ and sunlight $H_2S, \: CO$ and sunlight $SO_2, \: NH_3$ and sunlight

Milicevic3306 asked in Air Pollution Mar 28, 2018

by Milicevic3306

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26

GATE2016-1-19
It was decided to construct a fabric filter, using bags of $0.45$ m diameter and $7.5$ m long, for removing industrial stack gas containing particulates. The expected rate of airflow into the filter is $10 \: m^3/s$. If the filtering velocity is $2.0$ m/min, the minimum number of bags (rounded to nearest higher integer) required for continuous cleaning operation is $27$ $29$ $31$ $32$

Milicevic3306 asked in Air Pollution Mar 28, 2018

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27

GATE2016-1-20
Match the items in Group - I with those in Group - II and choose the right combination. ... $P - 1; \: Q - 4; \: R - 2; \: S - 3$

Milicevic3306 asked in Water and Waste Water Quality and Treatment Mar 28, 2018

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28

GATE2016-1-50
Effluent from an industry ‘A’ has a pH of $4.2$. The effluent from another industry ‘B’ has double the hydroxyl (OH) ion concentration than the effluent from industry ‘A’. pH of effluent from the industry ‘B’ will be ______

Milicevic3306 asked in Water and Waste Water Quality and Treatment Mar 28, 2018

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29

GATE2016-1-51
An electrostatic precipitator (ESP) with $5600\:m^2$ of collector plate area is $96$ percent efficient in treating $185\:m^3/s$ of flue gas from a $200$ MW thermal power plant. It was found that in order to achieve $97$ percent efficiency, the collector plate ... $99$ percent, the ESP collector plate area (expressed in $m^2$) would be ______

Milicevic3306 asked in Air Pollution Mar 28, 2018

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30

GATE2016-1-52
The $2$-day and $4$-day BOD values of a sewage sample are $100$ mg/L and $155$ mg/L, respectively. The value of BOD rate constant (expressed in per day) is __________

Milicevic3306 asked in Water and Waste Water Quality and Treatment Mar 28, 2018

by Milicevic3306

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31

GATE2017 CE-1: 14
The wastewater from a city, containing a high concentration of biodegradable organics, is being steadily discharged into a flowing river at a location S. If the rate of aeration of the river water is lower than the rate of degradation of the organics, then the ... the location S. remains constant all along the length of the river. is lowest at a point downstream of the location S.

Milicevic3306 asked in Water and Waste Water Quality and Treatment Mar 26, 2018

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32

GATE2017 CE-1: 52
The equivalent sound power level (in dB) of the four sources with the noise levels of $60$ dB, $69$ dB, $70$ dB and $79$ dB is ______

Milicevic3306 asked in Noise Pollution Mar 26, 2018

by Milicevic3306

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33

GATE2017 CE-1: 53
The spherical grit particles, having a radius of $0.01$ mm and specific gravity of $3.0$, need to be separated in a settling chamber. It is given that $g=9.81 \: m/s^2$ the density of the liquid in the settling chamber $=1000 \: kg/m^3$ the ... settling chamber $=10^{-6} \: m^2/s$ Assuming laminar conditions, the settling velocity (in mm/s, up to one decimal place) is __________

Milicevic3306 asked in Fluid Mechanics Mar 26, 2018

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34

GATE2017 CE-1: 54
Two wastewater streams A and B, having an identical ultimate BOD are getting mixed to form the stream C. The temperature of the stream A is $20^{\circ}C$ and the temperature of the stream C is $10^{\circ}C$. It is given that the $5$-day BOD of the stream A measured ... The $5-$day BOD (in mg\I, up to one decimal place ) of the stream C, calculated at $10^{\circ} C$, is _________

Milicevic3306 asked in Water and Waste Water Quality and Treatment Mar 26, 2018

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35

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 _________

Milicevic3306 asked in Water and Waste Water Quality and Treatment Mar 26, 2018

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36

GATE2015-2-21
$SO_2$ and $CO$ adversely affect oxygen carrying capacity of blood and functioning of lungs respectively functioning of the respiratory system and brain respectively functioning of the respiratory system and oxygen carrying capacity of blood respectively functioning of air passages and chest respectively

Milicevic3306 asked in Air Pollution Mar 26, 2018

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37

GATE2015-2-47
A landfill is to be designed to serve a population of $200000$ for a period of $25$ years. The solid waste (SW) generation is $2$ kg/person/day. The density of the un-compacted SW is $100 \: kg/m^3$ and a compaction ratio of $4$ is suggested. The ratio of compacted fill (i.e., SW+cover) to compacted SW is $1.5$. The landfill volume (in $million \: m^3$) required is _________.

Milicevic3306 asked in Municipal Solid Wastes Mar 26, 2018

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38

GATE2015-2-48
A water treatment plant of capacity, $1 \: m^3/s$ has filter boxed of dimensions $6 \; m \times 10 \: m$. Loading rate to the filters is $120 \: m^3/day/m^2$. When two of the filters are out of service for back washing, the loading rate (in $m^3/day/m^2$) is _________.

Milicevic3306 asked in Water and Waste Water Quality and Treatment Mar 26, 2018

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39

GATE2015-2-49
Ultimate BOD of a river water sample is $20$ mg/L. BOD rate constant (natural log) is $0.15 \: day^{-1}$. The respective values of BOD (in $\%$) exerted and remaining after $7$ days are: $45$ and $55$ $55$ and $45$ $65$ and $35$ $75$ and $25$

Milicevic3306 asked in Environmental Engineering Mar 26, 2018

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40

GATE2015-2-50
In a wastewater treatment plant, primary sedimentation tank (PST) designed at an overflow rate of $32.5 \: m^3/day/m^2$ is $32.5$ m long, $8.0$ m wide and liquid depth of $2.25$ m. If the length of the weir is $75$ m, the weir loading rate (in $m^3/day/m$) is ______.

Milicevic3306 asked in Water and Waste Water Quality and Treatment Mar 26, 2018

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11.9k points