GATE CE format:nat PYQs & Answers — Page 44 — Exam Papers

Questions 431–440 of 495. Imported answers require independent review unless marked reviewed.

Topic practice 495 questionsPage 44 of 50

The infiltration rate

in a basin under ponding condition is given by

, where,

is in mm/h and

is time in hour. Total depth of infiltration (in mm, up to one decimal place) during the last 20 minutes of a storm of 30 minutes duration is _____

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A flocculation tank contains 1800 m³ of water, which is mixed using paddles at an average velocity gradient G of 100/s. The water temperature and the corresponding dynamic viscosity are 30°C and 0.798×10⁻³ N s/m², respectively. The theoretical power required to achieve the stated value of G (in kW, up to two decimal places) is ______

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In a laboratory, a flow experiment is performed over a hydraulic structure. The measured values of discharge and velocity are 0.05 m³/s and 0.25 m/s, respectively. If the full scale structure (30 times bigger) is subjected to a discharge of 270 m³/s, then the time scale (model to full scale) value (up to two decimal places) is _____

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A coal containing 2% sulfur is burned completely to ash in a brick kiln at a rate of 30 kg/min. The sulfur content in the ash was found to be 6% of the initial amount of sulfur present in the coal fed to the brick kiln. The molecular weights of S, H and O are 32, 1 and 16 g/mole, respectively. The annual rate of sulfur dioxide (SO₂) emission from the kiln (in tonnes/year, up to two decimal places) is ______

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A water sample analysis data is given below.

Ion	Concentration, mg/L	Atomic Weight
Ca²⁺	60	40
Mg²⁺	30	24.31
HCO₃⁻	400	61

The carbonate hardness (expressed as mg/L of CaCO₃, up to one decimal place) for the water sample is _____

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At a small water treatment plant which has 4 filters, the rates of filtration and backwashing are 200 m

/d/m

and 1000 m

/d/m

, respectively. Backwashing is done for 15 min per day. The maturation, which occurs initially as the filter is put back into service after cleaning, takes 30 min. It is proposed to recover the water being wasted during backwashing and maturation. The percentage increase in the filtered water produced (up to two decimal places) would be _____

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The ultimate BOD (

) 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 per day and temperature coefficient

= 1.047, the BOD value (in mg/L, up to one decimal place) after three days of incubation at 27°C for this wastewater will be _____

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A schematic flow diagram of a completely mixed biological reactor with provision for recycling of solids is shown in the figure.

Diagram for Civil Engineering question 52

S₀, S = readily biodegradable soluble BOD, mg/L Q, Qᵣ, Qw = flow rates, m

/d X₀, X, Xₑ, Xᵤ = microorganism concentrations (mixed-liquor volatile suspended solids or MLSS), mg/L

The mean cell residence time (in days, up to one decimal place) is _____

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A waste activated sludge (WAS) is to be blend 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.

Parameter	WAS	GW
Carbon (g)	54	360
Nitrogen (g)	10	6

The ratio of WAS to GW required (up to two decimal places) to achieve a blend C:N ratio of 20:1 on dry basis _____

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The space mean speed (kmph) and density (vehicles/km) of a traffic stream are linearly related. The free flow speed and jam density are 80 kmph and 100 vehicles/km respectively. The traffic flow (in vehicles/h, up to one decimal place) corresponding to a speed of 40 kmph is _____

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