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Recent questions and answers in Water and Waste Water Quality and Treatment
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1
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 _______________________
ishita29
answered
in
Water and Waste Water Quality and Treatment
Feb 3, 2023
by
ishita29
110
points
gatecivil-2021-set2
numerical-answers
sludge-disposal
activated-sludge-process
1
vote
0
answers
2
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
by
Don6
130
points
gatecivil
water-treatment-plant
bod-rate-constant
wastewater
0
votes
0
answers
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
by
go_editor
5.3k
points
gatecivil-2021-set2
basics-of-water-quality-standards
physical-chemical-and-biological-parameters
hardness-of-water
0
votes
0
answers
4
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
by
Arjun
13.0k
points
gatecivil-2021-set1
primary-secondary-treatment
biochemical-oxygen-demand
0
votes
0
answers
5
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
by
Arjun
13.0k
points
gatecivil-2021-set1
primary-secondary-treatment
wastewater
0
votes
0
answers
6
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
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in
Water and Waste Water Quality and Treatment
Feb 20, 2021
by
Arjun
13.0k
points
gatecivil-2021-set1
water-quality-index
fermentation-method
0
votes
0
answers
7
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
by
Arjun
13.0k
points
gatecivil-2021-set1
chemical-biological-parameters
0
votes
0
answers
8
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
by
Arjun
13.0k
points
gatecivil-2021-set1
numerical-answers
sludge-disposal
activated-sludge-treatement
1
vote
1
answer
9
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
by
Vipin6419
140
points
gate2017-ce-1
numerical-answers
steady-rate
water-and-waste-water-quality-and-treatment
environmental-engineering
0
votes
0
answers
10
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
by
go_editor
5.3k
points
gate2020-ce-1
numerical-answers
effluent-discharge-standards
biochemical-oxygen-demand
0
votes
0
answers
11
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
by
go_editor
5.3k
points
gate2020-ce-1
water-and-waste-water
numerical-answers
wastewater-discharge
bod
0
votes
0
answers
12
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
by
go_editor
5.3k
points
gate2020-ce-2
environmental-engineering
effluent-discharge-standards
biological-oxygen-demand
0
votes
0
answers
13
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
by
go_editor
5.3k
points
gate2020-ce-2
numerical-answers
physical-chemical-and-biological-parameters
ph-scale
0
votes
0
answers
14
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
by
go_editor
5.3k
points
gate2020-ce-2
numerical-answers
water-and-waste-water
physical-chemical-and-biological-parameters
0
votes
0
answers
15
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
4.0k
points
gate2017-ce-2
water-and-waste-water-quality-and-treatment
environmental-engineering
sludge-disposal
activated-sludge-process
0
votes
0
answers
16
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
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in
Water and Waste Water Quality and Treatment
Aug 7, 2019
by
gatecse
4.0k
points
gate2017-ce-2
numerical-answers
water-and-waste-water-quality-and-treatment
environmental-engineering
biological-oxygen-demand
0
votes
0
answers
17
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
13.0k
points
gate2019-ce-1
water-and-waste-water
environmental-engineering
water-treatment-plant
sedimentation
0
votes
0
answers
18
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
13.0k
points
gate2019-ce-1
numerical-answers
water-and-waste-water
environmental-engineering
wastewater-treatment-plant
chlorination-process
0
votes
0
answers
19
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
13.0k
points
gate2019-ce-2
water-and-waste-water
environmental-engineering
alkalinity
0
votes
0
answers
20
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
13.0k
points
gate2019-ce-2
water-and-waste-water
environmental-engineering
water-treatment-plant
0
votes
0
answers
21
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
13.0k
points
gate2019-ce-2
numerical-answers
water-and-waste-water
environmental-engineering
water-treatment-plant
0
votes
0
answers
22
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
13.0k
points
gate2019-ce-2
numerical-answers
environmental-engineering
water-and-waste-water
effluent-discharge-standards
0
votes
0
answers
23
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
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in
Water and Waste Water Quality and Treatment
Mar 28, 2018
by
Milicevic3306
11.9k
points
gate2016-ce-2
numerical-answers
environmental-engineering
water-and-waste-water-quality-and-treatment
drinking-water-treatment
0
votes
0
answers
24
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
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in
Water and Waste Water Quality and Treatment
Mar 28, 2018
by
Milicevic3306
11.9k
points
gate2016-ce-2
numerical-answers
environmental-engineering
water-and-waste-water-quality-and-treatment
hardness-of-water
0
votes
0
answers
25
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 $40$ $165$ $195$ $205$
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Water and Waste Water Quality and Treatment
Mar 28, 2018
by
Milicevic3306
11.9k
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gate2016-ce-2
water-and-waste-water-quality-and-treatment
environmental-engineering
basics-of-water-quality-standards
0
votes
0
answers
26
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 ________
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Water and Waste Water Quality and Treatment
Mar 28, 2018
by
Milicevic3306
11.9k
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gate2016-ce-2
numerical-answers
water-and-waste-water-quality-and-treatment
environmental-engineering
wastewater
incubation-temperature
0
votes
0
answers
27
GATE2016-1-18
Crown corrosion in a reinforced concrete sewer is caused by: $H_2S$ $CO_2$ $CH_4$ $NH_3$
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Water and Waste Water Quality and Treatment
Mar 28, 2018
by
Milicevic3306
11.9k
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gate2016-ce-1
water-and-waste-water
water-resources-engineering
concrete-sewer
sewerage-treatment
0
votes
0
answers
28
GATE2016-1-20
Match the items in Group - I with those in Group - II and choose the right combination. ... $P - 1; \: Q - 4; \: R - 2; \: S - 3$
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Mar 28, 2018
by
Milicevic3306
11.9k
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gate2016-ce-1
water-and-waste-water-quality-and-treatment
environmental-engineering
activated-sludge-process
0
votes
0
answers
29
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 ______
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Water and Waste Water Quality and Treatment
Mar 28, 2018
by
Milicevic3306
11.9k
points
gate2016-ce-1
numerical-answers
water-and-waste-water-quality-and-treatment
environmental-engineering
effluent-discharge-standards
0
votes
0
answers
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 __________
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Water and Waste Water Quality and Treatment
Mar 28, 2018
by
Milicevic3306
11.9k
points
gate2016-ce-1
numerical-answers
environmental-engineering
water-and-waste-water-quality-and-treatment
sewage
bod-rate-constant
0
votes
0
answers
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.
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Water and Waste Water Quality and Treatment
Mar 26, 2018
by
Milicevic3306
11.9k
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gate2017-ce-1
environmental-engineering
water-and-waste-water-quality-and-treatment
biodegradation
0
votes
0
answers
32
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 _________
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Water and Waste Water Quality and Treatment
Mar 26, 2018
by
Milicevic3306
11.9k
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gate2017-ce-1
numerical-answers
water-and-waste-water-quality-and-treatment
environmental-engineering
biological-oxygen-demand
0
votes
0
answers
33
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 _________.
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Water and Waste Water Quality and Treatment
Mar 26, 2018
by
Milicevic3306
11.9k
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gate2015-ce-2
numerical-answers
water-and-waste-water
environmental-engineering
water-treatment-plant
1
vote
0
answers
34
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 ______.
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in
Water and Waste Water Quality and Treatment
Mar 26, 2018
by
Milicevic3306
11.9k
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gate2015-ce-2
numerical-answers
water-and-waste-water-quality-and-treatment
environmental-engineering
wastewater-treatment-plant
0
votes
0
answers
35
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
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Water and Waste Water Quality and Treatment
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by
Milicevic3306
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gate2015-ce-1
water-and-waste-water-quality-and-treatment
environmental-engineering
sewage-treatment
0
votes
0
answers
36
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 $(v) = 1.10 \times 10^{-6} m^2/s$.
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Water and Waste Water Quality and Treatment
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by
Milicevic3306
11.9k
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gate2015-ce-1
numerical-answers
water-and-waste-water-quality-and-treatment
environmental-engineering
water-treatment-plant
0
votes
0
answers
37
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 $1.68$ $12.63$ $15.46$ $1.37$
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by
Milicevic3306
11.9k
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gate2014-ce-2
water-and-waste-water-quality-and-treatment
environmental-engineering
de-oxygenation-rate-constant
waste-water-stream
0
votes
0
answers
38
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 __________
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Water and Waste Water Quality and Treatment
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by
Milicevic3306
11.9k
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gate2014-ce-2
numerical-answers
water-and-waste-water-quality-and-treatment
environmental-engineering
effluent-discharge-standards
sewage-treatment
0
votes
0
answers
39
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 _______
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Mar 26, 2018
by
Milicevic3306
11.9k
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gate2014-ce-2
numerical-answers
water-and-waste-water-quality-and-treatment
environmental-engineering
surface-water-treatment
0
votes
0
answers
40
GATE2014-2-21
The dominating microorganisms in an activated sludge process reactor are aerobic heterotrophs anaerobic heterotrophs autotrophs phototrophs
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Water and Waste Water Quality and Treatment
Mar 26, 2018
by
Milicevic3306
11.9k
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gate2014-ce-2
water-and-waste-water-quality-and-treatment
environmental-engineering
activated-sludge-process
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