Civil Engineering
GATE CE area:environmental-engineering PYQs
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Questions 61–70 of 110. Imported answers require independent review unless marked reviewed.
Question 33
Open questionCEMCQ2 marksNeeds review
A water filtration unit is made of uniform-size sand particles of 0.4 mm diameter with a shape factor of 0.84 and specific gravity of 2.55. The depth of the filter bed is 0.70 m and the porosity is 0.35. The filter bed is to be expanded to a porosity of 0.65 by hydraulic backwash. If the terminal settling velocity of sand particles during backwash is 4.5 cm/s, the required backwash velocity is
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Ammonia nitrogen is present in a given wastewater sample as the ammonium ion (NH₄⁺) and ammonia (NH₃). If pH is the only deciding factor for the proportion of these two constituents, which of the following is a correct statement?
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Open questionCENAT2 marksNeeds review
A baghouse filter has to treat 12 m³/s of waste gas continuously. The baghouse is to be divided into 5 sections of equal cloth area such that one section can be shut down for cleaning and/or repair, while the other 4 sections continue to operate. An air-to-cloth ratio of 6.0 m³/min-m² cloth will provide sufficient treatment to the gas. The individual bags are of 32 cm in diameter and 5 m in length. The total number of bags (in integer) required in the baghouse is ________.
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An activated sludge process (ASP) is designed for secondary treatment of 750 m³/day of municipal wastewater. After primary clarifier, the ultimate BOD of the influent, which enters into ASP reactor is 200 mg/L. Treated effluent after secondary clarifier is required to have an ultimate BOD of 20 mg/L. Mix liquor volatile suspended solids (MLVSS) concentration in the reactor and the underflow is maintained as 3000 mg/L and 12000 mg/L, respectively. The hydraulic retention time and mean cell residence time are 0.2 day and 10 days, respectively. A representative flow diagram of the ASP is shown below. The underflow volume (in m³/day, round off to one decimal place) of sludge wastage is ________.
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A secondary clarifier handles a total flow of 9600 m³/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 mg/L. The clarifier is required to thicken the solids to 1200 mg/L, and hence it is to be designed for a solid flux of 3.2 kg/m².h. The surface area of the designed clarifier for thickening (in m², in integer) is ________.
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A grit chamber of rectangular cross-section is to be designed to remove particles with diameter of 0.25 mm and specific gravity of 2.70. The terminal settling velocity of the particles is estimated as 2.5 cm/s. The chamber is having a width of 0.50 m and has to carry a peak wastewater flow of 9720 m³/d giving the depth of flow as 0.75 m. If a flow-through velocity of 0.3 m/s has to be maintained using a proportional weir at the outlet end of the chamber, the minimum length of the chamber (in m, in integer) to remove 0.25 mm particles completely is ________.
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Open questionCEMCQ1 markNeeds review
During chlorination process, aqueous (aq) chlorine reacts rapidly with water to form Cl⁻, HOCl, and H⁺ as shown below
Cl₂ (aq) + H₂O ⇌ HOCl + Cl⁻ + H⁺
The most active disinfectant in the chlorination process from amongst the following, is
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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
, where,
(in mg/litre) is the oxygen equivalent of the organics remaining at time
and
(in d
) is the degradation rate constant.
is the oxygen equivalent of organic matter at time,
.In the above context, the correct expression is
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An amount of 35.67 mg HCl is added to distilled water and the total solution volume is made to one litre. The atomic weights of H and Cl are 1 and 35.5, respectively. Neglecting the dissociation of water, the pH of the solution, is
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A gas contains two types of suspended particles having average sizes of 2 μm and 50 μm. Among the options given below, the most suitable pollution control strategy for removal of these particles is
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