Description : Pick up the correct statement from the following: (A) Detention period for plain sedimentation tanks ranges between 4 to 8 hours (B) Detention period for sedimentation tanks, using coagulants usually ... in sedimentation tanks, is generally limited to 0.3 m/minute (D) All the above
Last Answer : (D) All the above
Description : In a sedimentation tank, the detention period for water ranges from __________ hours. (A) 2 to 4 (B) 8 to 12 (C) 16 to 20 (D) 24 to 32
Last Answer : (A) 2 to 4
Description : The detention period for plain sedimentation water tanks, is usually (A) 4 to 8 hours (B) 8 to 16 hours (C) 16 to 24 hours (D) 24 to 36 hours
Last Answer : (D) 24 to 36 hours
Description : The detention period for plain sedimentation water tanks, is usually A. 4 to 8 hours B. 8 to 16 hours C. 16 to 24 hours D. 24 to 36 hours
Last Answer : ANS: A
Description : The efficiency of sedimentation tank does not depend upon (A) Depth of tank (B) Length of tank (C) Detention period (D) Velocity of water
Last Answer : (D) Velocity of water
Description : Pick up the incorrect statement from the following: A. Septic tanks are horizontal continuous flow type of sedimentation tanks B. Septic tanks are generally provided a detention period of 12 to 36 hours C ... covered and high vent shafts are provided for the escape of foul gases D. None of these
Last Answer : ANS: D
Description : Velocity of flow of water in plain sedimentation water tank, is normally kept (A) 3 cm/minute (B) 10 cm/minute (C) 20 cm/minute (D) 30 cm/minute
Last Answer : (D) 30 cm/minute
Description : Normal values of overflow rate for plain sedimentation tank using coagulants, is (A) 750 to 1000 litres/hr/m2 (B) 1000 to 1250 litres/hr/m2 (C) 1250 to 1500 litres/hr/m2 (D) 1500 litres/hr/m
Last Answer : (B) 1000 to 1250 litres/hr/m2
Description : Normal values of overflow rate for plain sedimentation tank, is (A) 250 to 500 litres/hr/m2 (B) 500 to 750 litres/hr/m2 (C) 750 to 1000 litres/hr/m2 (D) 1000 to 1250 litres/hr/m
Last Answer : (B) 500 to 750 litres/hr/m
Description : The normal value of over flow rates for plain primary sedimentation tanks, ranges between A. 25,000 to 35,000 litres/sqm/day B. 40,000 to 50,000 litres/sqm/day C. 50,000 to 60,000 litres/sqm/day D. 80,000 to 100,000 litres/sqm/day
Last Answer : ANS: B
Description : Flow through period, in sedimentation tanks, is (A) Equal to detention period (B) More than detention period (C) Less than detention period (D) Detention period divided by displacement efficiency
Last Answer : (C) Less than detention period
Description : The settling velocity of the particles larger than 0.06 mm in a settling tank of depth 2.4 is 0.33 m per sec. The detention period recommended for the tank, is A. 30 minutes B. 1 hour C. 1 hour and 30 minutes D. 2 hours
Description : In sewage treatment, the detention period allowed for oxidation ponds ranges from __________ weeks. (A) 1 to 2 (B) 4 to 5 (C) 9 to 10 (D) 15 to 20
Last Answer : (B) 4 to 5
Description : Detention period of a settling tank is (A) Average theoretical time required for water to flow through the tank (B) Time required for flow of water to fill the tank fully (C) Average time for which water is retained in tank (D) All the above
Description : In plain sedimentation tanks under normal conditions, impurities are removed upto (A) 60 % (B) 70 % (C) 80 % (D) 90 %
Last Answer : (B) 70 %
Description : Normal values of overflow rate for plain sedimentation tanks in litres/hr/m2 , generally range between (A) 100 to 250 (B) 250 to 500 (C) 500 to 750 (D) 750 to 1000
Last Answer : (C) 500 to 750
Description : Pipe A usually fills a tank in 2 hours. On account of a leak at the bottom of the tank, it takes pipe A 30 more minutes to fill the tank. How long will the leak take to empty a full tank if pipe A is shut? a) 4 hours b) 3 hours c) 6 hours d) 8 hours e) 10 hours
Last Answer : portion of the tank filled by the pipe A in 1 hour = ½ of the tank let the portion of the tank emptied because of the leak in 1 hour be 1/x of the tank therefore, in 1 hour , portion of the tank filled = 1/2 - 1 ... 1/2 - 1/x = 1/2.5 or x = 10 hence, it takes 10 hours to empty a full tank Answer: e)
Description : The detention period in a septic tank is assumed (A) 20 minutes (B) 25 minutes (C) 30 minutes (D) 40 minute
Last Answer : (C) 30 minutes
Description : The normal values of over flow rates for secondary sedimentation tanks, ranges between A. 25,000 to 35,000 litres/sqm/day B. 40,000 to 50,000 litres/sqm/day C. 50,000 to 60,000 litres/sqm/day D. 80,000 to 10,000 litres/sqm/day
Description : The dimensions of a rectangular settling tank are: length 24 m, width 6 m and depth 3 m. If 2 hour detention period for tanks is recommended, the rate of flow of sewage per hour, is A. 204 cu.m B. 208 cu.m C. 212 cu.m D. 216 cu.m
Description : The width of a settling tank with 2 hour detention period for treating sewage 378 cu m per hour, is A. 5 m B. 5.5 m C. 6.5 m D. 7 m
Description : The flow of water gets retarded, in (A) Settling tank (B) Sedimentation tank (C) Clarifier (D) All the above
Description : Distribution of wash water is provided in (A) Sedimentation tank (B) Slow sand filter (C) Rapid gravity filter (D) All the above
Last Answer : (C) Rapid gravity filter
Description : If L, B and D length, breadth and depth of water in a rectangular sedimentation tank of total discharge Q, the settling velocity, is (A) Q/H (B) Q/D (C) Q/(D × B) (D) Q/(L × B)
Last Answer : (D) Q/(L × B)
Description : During sewage treatment, effluent from which one of the following treatment units has minimum wt/vol amount of suspended solids? (a) Detritus channel (b) Primary sedimentation tank (c) Secondary sedimentation tank (d) Activated sludge process aeration tank
Last Answer : (d) Activated sludge process aeration tank
Description : The normal values of over flow rates for sedimentation tanks using coagulant, ranges between A. 25,000 to 35,000 litres/sqm/day B. 40,000 to 50,000 litres/sqm/day C. 50,000 to 60,000 litres/sqm/day D. 80,000 to 100,000 litres/sqm/day
Last Answer : ANS: C
Description : For a continuous flow type of sedimentation tanks A. Width of the tank is normally kept about 6 m B. Length of the tank is normally kept 4 to 5 times the width C. Maximum horizontal flow velocity is limited to 0.3 m/minute D. All the above
Last Answer : D
Description : The magnitude of energy released by an earthquake is usually measured on Richter scale which ranges between (a) 0 to 7 (b) 0 to 8 (c) 0 to 9 (d) 0 to 12
Last Answer : (c) 0 to 9
Description : The detention time (t) of a settling tank, may be defined as the time required for A. A particle to travel along its length B. A particle to travel from top surface to bottom sludge zone C. The flow of sewage to fill the tank D. None of these
Description : The detention time of a circular tank of diameter d and water depth H, for receiving the sewage Q per hour, is A. d² (0.011d + 0.785H)/Q B. d (0.022d + 0.085H)/Q C. d (0.785d + 0.011H)/Q D. d (0.285d + 0.011H)/Q
Description : For a grit chamber, if the recommended velocity of flow is 0.2 m/sec and detention period is 2 minutes, the length of the tank, is A. 16 m B. 20 m C. 24 m D. 30 m
Description : Pipe A can fill a water tank in 8 hours, Pipe B can fill the same tank in 12 hours and Pipe C can empty the tank in 24 hours. If all three pipes are opened together, in how many hours will the tank be completely filled or empty? a) 4.8 hours b) 5 hours c) 5.4 hours d) 6 hours e) 7.2 hours
Last Answer : If all the three pipes are opened together, in one hour they will fill 1/8 + 1/12 – 1/24 = (3+2-1)/24 = 1/6 part of tank. So, to fill it completely it will take 6 hours. Answer is: d)
Description : Three pipes A, B and C can fill a tank in 6 hours. After working at it together for 2 hours, C is closed and A and B can fill the remaining part in 7 hours. The number of hours taken by C alone to fill the tank is: a) 10 b) 14 c) 12 d) 13 e) 15
Last Answer : (A+B+C) - (A+B) (A+B+C) =1/6 and (A+B+C) in 2hrs=2/6 and remaining part 1-2/6=2/3. So (A+B) in 7 hrs is 2/ (3*7) =2/21. 1/6-2/21=1/14 so answer is 14. Answer: b)
Description : The function of sedimentation tank in sewage treatment is to: (1) Disinfect the sewage (2) Remove water content (3) Aerate the sewage (4) Remove suspended solids
Last Answer : (4) Remove suspended solids Explanation: The function of sedimentation tank in the sewage treatment is to remove suspended solids.
Description : The ratio of design discharge to the surface area of a sedimentation tank is called A. Surface loading B. Overflow rate C. Overflow velocity D. All of these
Description : The settlement of a particle in sedimentation tank, is affected by A. Velocity of flow B. Viscosity of water C. Size and shape of solid D. All the above
Description : In a sedimentation tank (length L, width B, depth D) the settling velocity of a particle for a discharge Q, is A. Q/(B × D) B. Q/(L × D) C. Q/L D. Q/(B × L)
Description : For treating the sewage of a large city, you will recommend A. A sedimentation tank and an activated sludge treatment plant B. A plant consisting of Imhoff tanks with low rate trickling filters C. Sedimentation tanks with high rate trickling filters D. None of these
Description : The discharge per unit plan area of a sedimentation tank, is generally called A. Over flow rate B. Surface loading C. Over flow velocity D. All the above
Description : Gravity settling process is not involved in the working of a (A) Hydrocyclone (B) Classifier (C) Dorr-thickener (D) Sedimentation tank
Last Answer : (A) Hydrocyclone
Description : Which of the following is the most efficient for removal of very finely divided suspended solids and colloidal matter from the polluted waterstream? (A) Sedimentation tank (B) Circular clarifier (C) Mechanical flocculation (D) Chemical coagulation
Last Answer : (D) Chemical coagulation
Description : During sewage treatment, the sewage is subjected to __________ treatment in Imhoff tank. (A) Filtration (B) Digestion (C) Sedimentation (D) Both (B) and (C)
Last Answer : (D) Both (B) and (C)
Last Answer : Remove suspended solids
Description : The value of Steric factor 'P' in the equation k = PZe E/RT usually ranges from (A) 1.0 to 10 -8 (B) 1.1 to 10 2 (C) 0.1 to 0.9 (D) None of these
Last Answer : (A) 1.0 to 10 -8
Description : The Constitution allows preventive detention but stipulates: (1) that no one should be detained beyond three months unless an Advisory Board authorizes detention beyond that period (2) that the grounds for ... nearest magistrate within a period of 24 hours of his arrest (4) All of the above
Last Answer : (1) that no one should be detained beyond three months unless an Advisory Board authorises detention beyond that period Explanation: Article 22 (4) provides that no law providing for preventive detention ... said period of 3 months that there is in it's opinion sufficient cause for such detention.
Description : In case of Imhoff tanks, A. The shape is rectangular B. Detention period is 2 hours C. The velocity of flow is restricted to 0.30 m/minute D. All the above
Description : Two pipes fills a tank in 12 hours and 15 hours respectively while a third pipe empties the tank in 18 hours. !f all three pipes operate simultaneously, in what time will the tank be full? a) 10 hours b) 10 10/17 hours c) 11 hours d) 9 hours e) 12 1/17 hours
Last Answer : b) 10 10/17 hours
Description : The emergency electrical power source on tank vessels over 500 GT on an international voyage, should be capable of continuous operation under emergency load for _____________. A. 6 hours B. 12 hours C. 18 hours D. 24 hours
Last Answer : Answer: C
Description : Two faucet A and B can fill a tank in 20 hours and 40 hours respectively. If they are opened simultaneously. Sometimes later, tap B was closed, then it takes total 14 hours to fill up the whole tank. After how many hours B was closed? A) 4 hours B) 15.2 hours C) 12 hours D) 17.6 hours
Last Answer : A Let x is the time when B is closed X(1/20+1/40)+14/20=1 X=4 hours