Please keep at least one language enabled. || కనీసం ఒక భాషను ఎంచుకోండి.
Question 1
ప్రశ్న 1
What is the principal objective of sedimentation in a conventional water-treatment plant?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Sedimentation separates particles whose effective settling velocity permits them to move downward under gravity. In conventional treatment it commonly follows coagulation and flocculation so that fine colloids have been converted into larger settleable flocs. Removing this particulate load reduces the burden on downstream filters. Sedimentation does not by itself remove all dissolved constituents or guarantee microbiological safety. Therefore Option A is correct.
వివరణ:
Question 2
ప్రశ్న 2
Which description correctly defines Type I or discrete settling?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Type I settling occurs in relatively dilute suspensions containing particles that do not significantly interact while settling. Each particle can therefore be treated as settling independently. Its size, shape and density remain essentially unchanged during the settling process. Removal of ideal discrete particles can be related directly to their terminal settling velocity and the tank surface overflow rate. Therefore Option A is correct.
వివరణ:
Question 3
ప్రశ్న 3
Which statement best describes Type II or flocculent settling?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Flocculent particles interact and combine as they move through the settling basin. Their effective size and mass can therefore increase during sedimentation. As flocs grow, their settling velocity can also change rather than remaining constant. Coagulated alum or ferric flocs in water-treatment clarifiers are important examples of flocculent suspensions. Therefore Option B is correct.
వివరణ:
Question 4
ప్రశ్న 4
Which statement correctly distinguishes Type III hindered or zone settling from Type IV compression settling?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
At sufficiently high solids concentrations, neighboring particles interfere with one another and the suspension can settle as a zone. A relatively distinct interface may then separate the settling solids mass from the clearer liquid above. At still higher concentrations near the bottom, particles come into contact and form a compressible structure. Further settlement then occurs primarily by compression under the weight of overlying solids. Therefore Option A correctly distinguishes Type III from Type IV settling.
వివరణ:
Question 5
ప్రశ్న 5
For a small spherical discrete particle settling in the Stokes-law regime, how does terminal settling velocity vary with particle diameter when all other relevant properties remain constant?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Stokes' law applies to small spherical particles settling under laminar conditions at sufficiently low Reynolds number. The terminal velocity contains particle diameter squared in its numerator. Thus doubling the diameter, while retaining the assumptions of the Stokes regime, would theoretically increase the settling velocity by a factor of four. The relation also depends on density difference, gravitational acceleration and fluid viscosity. Therefore Option A is correct.
వివరణ:
Question 6
ప్రశ్న 6
What is the surface overflow rate of an ideal sedimentation tank having flow Q and plan surface area A?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Surface overflow rate is defined as the flow passing through the tank divided by its horizontal plan area. Its dimensions are those of velocity, such as m³/m²·d or equivalently m/d. In ideal Type I settling theory it represents the critical settling velocity associated with complete removal. It is also commonly called surface loading rate. Therefore Option A is correct.
వివరణ:
Question 7
ప్రశ్న 7
In an ideal horizontal-flow sedimentation tank treating discrete particles, which particles are theoretically removed completely?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For ideal Type I settling, the critical settling velocity equals the surface overflow rate Q/A. A particle settling at that velocity and entering at the water surface reaches the tank bottom by the time the water reaches the outlet. Faster-settling particles reach the bottom even earlier. Consequently particles with settling velocity equal to or greater than the overflow rate are theoretically removed completely. Therefore Option A is correct.
వివరణ:
Question 8
ప్రశ్న 8
An ideal sedimentation tank has a surface overflow rate of 30 m/day. For uniformly distributed discrete particles having a settling velocity of 18 m/day, what theoretical fraction of these particles is removed?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For discrete particles with settling velocity below the overflow rate, the ideal removal fraction is the ratio of particle settling velocity to surface overflow rate. Here the ratio is 18/30. This equals 0.60, or 60 percent. The calculation assumes ideal flow, uniform particle distribution and no flocculation or short-circuiting. Therefore Option B is correct.
వివరణ:
Question 9
ప్రశ్న 9
For ideal discrete-particle settling at fixed flow and plan area, what is the theoretical effect of simply increasing tank depth while keeping the surface overflow rate unchanged?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For ideal Type I settling, the critical removal relationship depends on Q divided by the plan area. Increasing depth increases both settling distance and hydraulic detention time in a compensating manner. The critical settling velocity therefore remains governed by the same surface overflow rate when Q and plan area remain unchanged. Practical tank depth remains important for hydraulics, sludge storage and flocculent settling even though the ideal discrete-settling criterion is depth-independent. Therefore Option A is correct.
వివరణ:
Question 10
ప్రశ్న 10
According to current MoHUA/CPHEEO water-treatment guidance, which surface-loading range is a typical design value for horizontal-flow circular sedimentation tanks or clariflocculators treating alum or iron floc at average design flow?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Current MoHUA/CPHEEO guidance gives a broad operating range for conventional flocculated-water sedimentation but identifies approximately 30 to 40 m³/m²·d as a typical design surface loading. These tanks commonly settle alum or iron flocs produced by coagulation and flocculation. The criterion refers to average design flow. Actual design should still consider raw-water behavior, process configuration and other hydraulic requirements. Therefore Option C is correct.
వివరణ:
Question 11
ప్రశ్న 11
What detention period is identified as a typical design value in current MoHUA/CPHEEO guidance for conventional horizontal-flow circular sedimentation or clariflocculation tanks treating coagulated water?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Current MoHUA/CPHEEO guidance lists approximately 2 to 2.5 hours as the typical detention period for conventional horizontal-flow circular sedimentation or clariflocculation units. This is much longer than the rapid-mixing detention period and longer than ordinary flocculation detention. It provides time for the developed flocs to settle from the clarification zone. Detention time must be considered together with surface loading rather than as the sole design criterion. Therefore Option C is correct.
వివరణ:
Question 12
ప్రశ్న 12
Which combination represents the typical current MoHUA/CPHEEO design values for plain sedimentation at average design flow?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The current MoHUA/CPHEEO water-treatment guidance gives 15 to 30 m³/m²·d as a typical design surface-loading range for plain sedimentation. It gives approximately 3 to 4 hours as the corresponding typical detention period. Plain sedimentation is intended primarily for readily settleable material such as sand, silt and clay rather than chemically formed floc. These values differ from those generally used for conventional coagulated-water clarifiers. Therefore Option A is correct.
వివరణ:
Question 13
ప్రశ్న 13
What length-to-width ratio is preferred by current MoHUA/CPHEEO guidance for rectangular sedimentation tanks?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
MoHUA/CPHEEO guidance states that rectangular settling tanks should preferably have a length-to-width ratio of about 3:1 to 5:1. A relatively narrow elongated basin helps establish a more orderly longitudinal flow path. Excessive width can increase susceptibility to cross-currents and eddies caused by wind, temperature effects and other disturbances. The ratio is a preferred design range rather than a claim that every tank must have one exact geometry. Therefore Option B is correct.
వివరణ:
Question 14
ప్రశ్న 14
Which statement correctly reflects current MoHUA/CPHEEO guidance on conventional sedimentation-tank depth?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
MoHUA/CPHEEO guidance indicates that sedimentation-basin depths commonly used in practice are approximately 2.5 to 5 m. A depth near 3 m is identified as a preferred practical value for many conventional tanks. Depth provides hydraulic volume and contributes to sludge-storage and flow-pattern requirements. It can also provide greater contact opportunity for flocculent particles even though ideal discrete-particle removal is governed by surface loading. Therefore Option A is correct.
వివరణ:
Question 15
ప్రశ్న 15
A sedimentation tank treats 18 MLD and is designed for a detention time of 2.5 hours. What theoretical water volume is required, neglecting separate sludge-storage volume?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
A flow of 18 MLD equals 18,000 m³/day. The detention period of 2.5 hours equals 2.5/24 day. Required volume is therefore Q multiplied by detention time. Thus V = 18,000 × 2.5/24 = 1,875 m³. Therefore Option C is correct.
వివరణ:
Question 16
ప్రశ్న 16
A conventional sedimentation tank must treat 24 MLD at an adopted surface overflow rate of 32 m³/m²·d. What plan area is required?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Surface overflow rate is Q/A, so the required area is A = Q/SOR. The design flow is 24,000 m³/day. Dividing 24,000 by 32 gives 750 m². This plan area satisfies the specified surface-loading criterion before other dimensional and hydraulic checks are made. Therefore Option C is correct.
వివరణ:
Question 17
ప్రశ్న 17
The sedimentation tank in the previous design has a required plan area of 750 m² and an adopted length-to-width ratio of 4:1. What approximate tank dimensions satisfy these data?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Let the width be B and the length be 4B. The area condition gives 4B² = 750. Therefore B is approximately 13.69 m and the corresponding length is about 54.77 m. Rounded appropriately, the dimensions are approximately 54.8 m by 13.7 m. Therefore Option B is correct.
వివరణ:
Question 18
ప్రశ్న 18
A sedimentation basin has a plan area of 750 m², water depth of 3.0 m and flow of 24 MLD. What theoretical detention time does the basin provide?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The basin water volume is 750 × 3.0 = 2,250 m³. The daily flow is 24,000 m³/day. The detention time is V/Q = 2,250/24,000 day. Multiplying by 24 hours per day gives 2.25 hours. Therefore Option C is correct.
వివరణ:
Question 19
ప్రశ్న 19
A sedimentation tank has a fixed plan area of 750 m². If flow increases from 24 MLD to 30 MLD, how does its surface overflow rate change?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
At 24 MLD, the surface loading is 24,000/750 = 32 m³/m²·d. At 30 MLD, the same tank area gives 30,000/750 = 40 m³/m²·d. Thus the overflow rate increases by 25 percent as the flow increases from 24 to 30 MLD. In ideal discrete settling, the higher overflow rate means fewer particles with lower settling velocities will be removed. Therefore Option C is correct.
వివరణ:
Question 20
ప్రశ్న 20
A clarifier carries 24 MLD and has a total effective effluent-weir length of 96 m. What is the weir loading rate?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Weir loading is the effluent flow divided by the total effective length of overflow weir. The flow is 24,000 m³/day and the weir length is 96 m. Therefore the loading is 24,000/96 = 250 m³ per metre of weir per day. This quantity is different from surface overflow rate, which uses plan area rather than weir length. Therefore Option C is correct.
వివరణ:
Question 21
ప్రశ్న 21
What is the primary hydraulic purpose of the inlet arrangement in a sedimentation tank?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
A good sedimentation inlet should distribute incoming water over the available cross-section as uniformly as practicable. It should dissipate excessive inlet momentum and avoid strong jets that bypass much of the tank volume. Uniform distribution promotes the intended settling environment throughout the basin. Poor inlet hydraulics can cause short-circuiting, turbulence and reduced effective detention. Therefore Option A is correct.
వివరణ:
Question 22
ప్రశ్న 22
Why are properly levelled and adequately distributed outlet weirs important in sedimentation-tank design?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Outlet weirs control how clarified water leaves the settling basin. If withdrawal is highly nonuniform, some parts of the tank can carry disproportionately large flow and develop undesirable local velocities. Adequate effective weir length reduces discharge per unit length and helps distribute withdrawal. Proper outlet hydraulics therefore support the settling performance established by the tank plan area and flow pattern. Therefore Option A is correct.
వివరణ:
Question 23
ప్రశ్న 23
What is meant by hydraulic short-circuiting in a sedimentation tank?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The theoretical detention time V/Q assumes the basin volume is used ideally. Real basins can contain preferential flow paths through which part of the influent reaches the outlet rapidly. This phenomenon reduces the effective time available for particles in that flow path to settle. Dead zones may exist simultaneously in other portions of the basin. Proper inlet, outlet and baffle design is therefore important for controlling short-circuiting.
వివరణ:
Question 24
ప్రశ్న 24
Why is regular sludge collection and removal necessary in a water-treatment sedimentation tank?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Solids removed from the water accumulate on the basin floor as sludge. Excessive accumulation reduces available tank volume and can interfere with hydraulic performance. Organic material within stored sludge can decompose, particularly under warm conditions, and may create undesirable water-quality effects. Deposits can also be disturbed and re-entrained if they are allowed to build excessively. Therefore systematic sludge collection and withdrawal are integral parts of sedimentation-tank operation.
వివరణ:
Question 25
ప్రశ్న 25
Consider the following statements about sedimentation tanks: I. For ideal discrete settling, surface overflow rate is the principal theoretical removal parameter. II. Flocculent particles can increase in size and settling velocity while settling. III. Detention time equals effective tank volume divided by flow. IV. Proper inlet, outlet and sludge-removal arrangements are necessary for practical tank performance. Which option is correct?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Statement I is correct because ideal Type I removal is governed by the relationship between particle settling velocity and Q/A. Statement II is correct because flocculent particles can agglomerate and change settling characteristics during their passage through the basin. Statement III is correct because hydraulic detention time is obtained from effective water volume divided by flow. Statement IV is correct because real sedimentation performance also depends on flow distribution, effluent withdrawal and proper solids management. Therefore all four statements are correct and Option D is the valid answer.
వివరణ:
Answer Key సమాధానాల పట్టిక
-
Question 1 ప్రశ్న 1Answer: A. To remove settleable suspended and flocculated particles by gravity before subsequent treatment సమాధానం: A.
-
Question 2 ప్రశ్న 2Answer: A. Particles settle individually without significant change in their size, shape or density సమాధానం: A.
-
Question 3 ప్రశ్న 3Answer: B. Particles aggregate while settling, so their size and settling velocity may increase with time and depth సమాధానం: B.
-
Question 4 ప్రశ్న 4Answer: A. Zone settling involves a mass of particles settling with a recognizable interface, whereas compression settling occurs when particles are in contact and further consolidation results from the weight of solids above సమాధానం: A.
-
Question 5 ప్రశ్న 5Answer: A. It is proportional to the square of particle diameter సమాధానం: A.
-
Question 6 ప్రశ్న 6Answer: A. Q/A సమాధానం: A.
-
Question 7 ప్రశ్న 7Answer: A. Particles whose settling velocity is equal to or greater than the surface overflow rate సమాధానం: A.
-
Question 8 ప్రశ్న 8Answer: B. 60% సమాధానం: B.
-
Question 9 ప్రశ్న 9Answer: A. The critical discrete-particle removal performance is theoretically unchanged సమాధానం: A.
-
Question 10 ప్రశ్న 10Answer: C. 30 to 40 m³/m²·d సమాధానం: C.
-
Question 11 ప్రశ్న 11Answer: C. 2 to 2.5 hours సమాధానం: C.
-
Question 12 ప్రశ్న 12Answer: A. Surface loading 15–30 m³/m²·d and detention about 3–4 h సమాధానం: A.
-
Question 13 ప్రశ్న 13Answer: B. Approximately 3:1 to 5:1 సమాధానం: B.
-
Question 14 ప్రశ్న 14Answer: A. Depths commonly used are about 2.5 to 5 m, with approximately 3 m being a preferred value సమాధానం: A.
-
Question 15 ప్రశ్న 15Answer: C. 1,875 m³ సమాధానం: C.
-
Question 16 ప్రశ్న 16Answer: C. 750 m² సమాధానం: C.
-
Question 17 ప్రశ్న 17Answer: B. 54.8 m long × 13.7 m wide సమాధానం: B.
-
Question 18 ప్రశ్న 18Answer: C. 2.25 h సమాధానం: C.
-
Question 19 ప్రశ్న 19Answer: C. It increases from 32 to 40 m³/m²·d సమాధానం: C.
-
Question 20 ప్రశ్న 20Answer: C. 250 m³/m·d సమాధానం: C.
-
Question 21 ప్రశ్న 21Answer: A. To distribute flow and suspended matter uniformly while minimizing large-scale turbulence సమాధానం: A.
-
Question 22 ప్రశ్న 22Answer: A. They promote relatively uniform withdrawal of clarified water and reduce localized high velocities near the outlet సమాధానం: A.
-
Question 23 ప్రశ్న 23Answer: A. A portion of the flow travels from inlet to outlet much faster than the theoretical mean detention time because of an unfavorable flow pattern సమాధానం: A.
-
Question 24 ప్రశ్న 24Answer: A. To prevent excessive sludge accumulation, loss of effective volume, decomposition and possible re-entrainment of settled solids సమాధానం: A.
-
Question 25 ప్రశ్న 25Answer: D. I, II, III and IV సమాధానం: D.