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Recent questions tagged water-and-waste-water-quality-and-treatment

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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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2

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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3

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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4

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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5

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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6

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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7

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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8

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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9

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

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10

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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11

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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12

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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13

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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14

GATE2015-1-20
Total Kjeldahl Nitrogen (TKN) concentration (mg/L as N) in domestic sewage is the sum of the concentrations of organic and inorganic nitrogen in sewage organic nitrogen and nitrate in sewage organic nitrogen and ammonia in sewage ammnia and nitrate in sewage

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

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15

GATE2015-1-50
Consider a primary sedimentation tank (PST) in a water treatment plant with Surface Overflow Rate (SOR) of $40\:m^3/m^2/d$. The diameter of the spherical particle which will have $90$ percent theoretical removal efficiency in this tank is ______ $\mu m$. Assume that settling velocity of the ... $g=9.81 \: m/s^2$; Kinematic viscosity of water $(v) = 1.10 \times 10^{-6} m^2/s$.

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

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16

GATE2014-2-47
A surface water treatment plant operates round the clock with a flow rate of $35 \: m^3/min$. The water temperature is $15^{\circ}C$ and jar testing indicated an alum dosage of $25$ mg/l with flocculation at a $Gt$ value of $4 \times 10^4$ producing optimal results. The alum quantity required for $30$ days (in kg) of operation of the plant is _______

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

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17

GATE2014-2-48
An effluent at a flow rate of $2670 \: m^3/d$ from a sewage treatment plant is to be disinfected. The laboratory data of disinfection studies with a chlorine dosage of $15$ mg/l yield the model $N_t=N_oe^{-0.145t}$ where $N_t=$ number of micro-organisms surviving ... (at $t=0$). The volume of disinfection unit (in $m^3$) required to achieve a $98\%$ kill micro-organisms is __________

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

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18

GATE2014-2-49
A waste water stream (flow $=2 m^3/s$, ultimate BOD$=90$ mg/l) is joining a small river (flow $=12 \: m^3/s$, ultimate BOD $=5$ mg/l). Both water streams get mixed up instantaneously. Cross-sectional area of the river is $50 \: m^2$. Assuming the de-oxygenation rate ... $10$ km downstream of the mixing point is $1.68$ $12.63$ $15.46$ $1.37$

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

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19

GATE2014-2-21
The dominating microorganisms in an activated sludge process reactor are aerobic heterotrophs anaerobic heterotrophs autotrophs phototrophs

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

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20

GATE2014-1-48
For a sample water with the ionic composition shown in the figure below, the carbonate and non-carbonate hardness concentrations (in mg/l as $CaCO_3$), respectively are: $200$ and $50$ $175$ and $75$ $75$ and $175$ $50$ and $200$

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

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21

GATE2014-1-46
$16$ MLD of water is flowing through a $2.5$ km long pipe of diameter $45$ cm. The chlorine at the rate of $32$ kg/d is applied at the entry of this pipe so that disinfected water is obtained at the exit. There is a proposal to increase the flow through this ... per day) to be applied to achieve the same degree of disinfection for the enhanced flow is $60.50$ $44.00$ $38.00$ $23.27$

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

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22

GATE2014-1-21
Some of the nontoxic metals normally found in natural water are arsenic lead and mercury calcium sodium and silver cadmium, chromium and copper iron, manganese and magnesium

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

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23

GATE Civil 2013 | Question: 43
A student began experiment for determination of $5$-day, $20^{\circ}C$ BOD on Monday. Since the $5$th day fell on Saturday, the final DO readings were taken on next Monday. On calculation, BOD (i.e. $7$ day, $20^{\circ}C$ was found to be $150$ ... )? Assume value of BOD rate constant $(k)$ at standard temperature of $20^{\circ}C$ as $0.23/day$ (base $e$). ___________

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

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24

GATE Civil 2013 | Question: 42
A settling tank in a water treatment plant is designed for a surface overflow rate of $30 \dfrac{m^3}{\text{day} \cdot m^2}$. Assume specific gravity of sediment particles $=2.65$, density of water $(\rho) =1000 \: kg/m^3$, dynamic viscosity of ... The approximate minimum size of particles that would be completely removed is $0.01$ mm $0.02$ mm $0.03$ mm $0.04$ mm

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

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25

GATE Civil 2013 | Question: 20
Some of the water quality parameters are measured by titrating a water sample with a titrant. Group I gives a list of parameters and Group-II gives the list of titrants. ... $P - 2, Q - 1, R - 4, S - 3$ $P - 4, Q - 3, R - 2, S - 1$

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

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26

GATE Civil 2013 | Question: 21
A water treatment plant is designed to treat $1 \: m^3/s$ of raw water. It has $14$ sand filters. Surface area of each filter is $50 \: m^2$. What is the loading rate (in $\dfrac{m^3}{\text{day} \cdot m^2}$) with two filters out of service for routine backwashing? __________

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

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27

GATE Civil 2012 | Question: 50
An activated sludge system (sketched below) is operating at equilibrium with the following information. Wastewater related data: flow rate $= 500 \: m^3/hour$, influent BOD $=150 \: mg/L$, effluent BOD $=10 \: mg/L$. Aeration tank related data: hydraulic retention ... ratio (in kg BOD per kg biomass per day) for the aeration tank is $0.015$ $0.210$ $0.225$ $0.240$

Milicevic3306 asked in Water and Waste Water Quality and Treatment Mar 25, 2018

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28

GATE Civil 2012 | Question: 51
An activated sludge system (sketched below) is operating at equilibrium with the following information. Wastewater related data: flow rate $=500 \: m^3/hour$, influent BOD $= 150 mg/L$, effluent BOD $=10 \: mg/L$ ... $24000$ $1000$ $800$ $33$

Milicevic3306 asked in Water and Waste Water Quality and Treatment Mar 25, 2018

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29

GATE Civil 2012 | Question: 42
A water sample has a pH of $9.25$. The concentration of hydroxyl ions in the water sample is $10^{-9.25}$ moles/L $10^{-4.75}$ mmoles/L $0.302$ mg/L $3.020$ mg/L

Milicevic3306 asked in Water and Waste Water Quality and Treatment Mar 25, 2018

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30

GATE Civil 2012 | Question: 43
A town is required to treat $4.2 \: m^3/min$ of raw water for daily domestic supply. Flocculating particles are to be produced by chemical coagulation. A column analysis indicated that an overflow rate of $0.2$ mm/s will produce satisfactory particles removal in a ... depth of $3.5$ m. The required surface area (in $m^2$) for settling is $210$ $350$ $1728$ $21000$

Milicevic3306 asked in Water and Waste Water Quality and Treatment Mar 25, 2018

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31

GATE Civil 2012 | Question: 20
A sample of domestic sewage is digested with silver sulphate, sulphuric acid, potassium dichromate and mercuric sulphate in chemical oxygen demand (COD) test. The digested sample is then titrated with standard ferrous ammonium sulphate (FAS) to determine the un-reacted amount of mercuric sulphate potassium dichromate silver sulphate sulphuric acid

Milicevic3306 asked in Water and Waste Water Quality and Treatment Mar 25, 2018

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32

GATE Civil 2012 | Question: 21
... $\textbf{[a]}$ and $\textbf{[r]}$ are false $\textbf{[a]}$ is true but $\textbf{[r]}$ is false

Milicevic3306 asked in Water and Waste Water Quality and Treatment Mar 25, 2018

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33

GATE2018 CE-2: 51
At a small water treatment plant which has $4$ filters, the rates of filteration and backwashing are $200 \: m^3/d/m^2$ and $1000 m^3/d/m^2$, respectively. Backwashing is done for $15$ min per day. The maturation, which ... the water being wasted during backwashing and maturation. The percentage increase in the filtered water produced (up to two decimal places) would be ______

gatecse asked in Water and Waste Water Quality and Treatment Feb 17, 2018

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34

GATE2018 CE-2: 14
As per $\text{IS }10500:2012$, for drinking water in the absence of alternate source of water, the permissible limits for chloride and sulphate, in mg/L, respectively are $250$ and 200$ $1000$ and 400$ $200$ and 250$ $500$ and 1000$

gatecse asked in Water and Waste Water Quality and Treatment Feb 17, 2018

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35

GATE2018 CE-1: 52
The ultimate BOD $(L_0)$ of a wastewater sample is estimated as $87 \%$ of COD. The COD of this wastewater is $300$ mg/L. Considering first order BOD reaction rate constant $k$ (use natural log) $= 0.23$ ... value in (in mg/L, up to one decimal place) after three days of incubation at $27^{\circ}$C for this wastewater will be _____

gatecse asked in Water and Waste Water Quality and Treatment Feb 17, 2018

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36

GATE2018 CE-1: 51
A water sample analysis data is given below, ... $CaCO_3$, up to one decimal place), for the water sample, is ____

gatecse asked in Water and Waste Water Quality and Treatment Feb 17, 2018

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37

GATE2018 CE-1: 53
A waste activated sludge (WAS) is to be blended with green waste (GW). The carbon (C) and nitrogen (N) contents, per kg of WAS and GW, on dry basis are given in the table. ... $C: N$ ratio of $20:1$ on dey basis is ____

gatecse asked in Water and Waste Water Quality and Treatment Feb 17, 2018

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38

GATE2018 CE-1: 33
A rapid sand filter comprising a number of filter beds is required to produce $99$ MLD of potable water. Consider water loss during backwashing as $5\%$, rate of filtration as 6.0 m/h and length to width ratio of filter bed as $1.35$. The width of each ... to take care of break-down, repair, and maintenance. The total number of filter beds required will be $19$ $20$ $21$ $22$

gatecse asked in Water and Waste Water Quality and Treatment Feb 17, 2018

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