d) more and more, 41. The detention period in coagulation tanks is usually kept as a) 1 to 2 minutes b) 30 to 45 minutes c) 2 to 6 hours d) 2 to 6 days Ans:c; The alum, when added as a coagulant in water a) does not require alkalinity in water for flocculation b) does not affect pH value of water c) increases pH value of water d) decreases pH value of water Ans:d The detention period and overflow rate respectively for plain sedimentation as compared to sedimentation with coagulation are generally, a) less and more PLEASE COMMENT BELOW WITH CORRECT ANSWER AND ITS DETAIL EXPLANATION. c) more and less 30 to 45 minutes ... D. 2 to 6 days. Environmental Engineering Objective Questions – Part 3, Environmental Engineering Objective Questions – Part 1, List Of 100 Environmental Engineering Objective Questions Part – 2, List Of 100 Environmental Engineering Objective Questions, Environmental Engineering Objective Questions – Part 4, Environmental Engineering Objective Questions – Part 5, Environmental Engineering Objective Questions – Part 6. iii) lesser efficiency in removal of bacteria - Civil Engineering Mcqs - Environmental Engineering Mcqs Your email address will not be published. The detention period in coagulation tanks is usually kept as_____? d) sodium permanganate, 46. This preview shows page 55 - 58 out of 66 pages.. 317. The detention period in coagulation tanks is usually kept as a) 1 to 2 minutes b) 30 to 45 minutes c) 2 to 6 hours d) 2 to 6 days Ans:c 44. Assume the detention period as 5 hours and velocity of flow as 15 cm / minute. c) A is true but R is false. d) dose of coagulant, 30. The dissolved oxygen level in natural unpolluted waters at normal temperature is found to be of the order of, a) 1 mg/litre The rate of filtration in slow sand filters in million litres per day per hectare is about, a) 50 to 60 Water Treatment Plants 85 Water Treatment processes For Rectangular tank. C 79. The Following Section consists Multiple Choice Questions on Water Supply Engineering. c) standard platinum scale 43. The settling velocity of a particle in a sedimentation tank increases if, a) particle size is decreased Period of cleaning of slow sand filters is about the A) 24 – 48 hours B) 10 – 12 days C) 2 – 3 months D) 1 – 2 year Ans. b) (ii) and (iii) b) does not affect pH value of water. Learn Environmental Engineering MCQ questions & answers are available for a Civil Engineering students to clear GATE exams, various technical interview, competitive examination, and another entrance exam. The velocity of flow of water in a sedimentation tank is about, a) 5 to 10 cm/sec. Select your answer based on the coding system given below: a) Both A and R are true and R is the correct explanation of A. a) 1 to 2 minutes. C 79. In order to provide sufficiently quiescent conditions for effective sedimentation of the suspended solids, the minimum detention period for the sewage in a septic tank should be 24 hours. 1 to 2 minutes B. d) 1.0 to 5.0 ppm, 32. iii) increase in temperature of water iv) higher efficiency in removal of bacteria, a) (i) and (ii) iv) decrease in temperature of water, a) (i) and (ii) c) increasing the surface area of tank b) 30 to 45 minutes d) decreasing the surface area of tank, 40. For a given discharge, the efficiency of sedimentation tank can be increased by, a) increasing the depth of tank (b) Circular tank-The circular sedimentation tank may have.. Sorry, you have Javascript Disabled! DESIGN ASPECTS 42 ♦Design Summary of Coagulation Tank: •No of tanks = 4 •Type of tank = Circular •Removal of sludge and scum = Mechanical •Diameter of tank, d = 18 m •Detention time, t = 2 hours •Depth of free board = 0.5 m •Sludge zone accumulation = 1 m •Total Depth of tank, D = 6.5 m Altafayaz2161@gmail.com 43. d) 1000 mg/litre, 33. C 2 to 6 hours. Carbonates in water produce A. temporary hardness B. permanent hardness C. acidity D. alkanity Answer => B A. temporary hardness B Assertion A: Slow sand filters are more efficient in removal of bacteria than rapid sand filters. b) copper sulphate 3. b) less and less A) Depth of tank B) Surface area of tank C) Both depth and surface area of tank D) None of the above Ans. Raw water passed through coagulation tank is supplied d) decreases pH value of water, 45. MCQs: The detention period for oxidation ponds is usually kept as_____? d) (ii) and (iv), 42. c) both depth and surface area of tank c) 0.5 to 1.0 ppm d) 1400 to 1500, 48. b) 1000 to 1250 litres/hour/ m2 Your email address will not be published. The detention period in coagulation tanks is usually kept as a) 1 to 2 minutes b) 30 to 45 minutes c) 2 to 6 hours d) 2 to 6 days Ans:c 45. b) does not affect pH value of water The length of rectangular sedimentation tank should not be more than, 35. c) both (a) and (b) b) 0.05 to 0.5 ppm d) none of the above, 39. c) (i) and (iv) Mcq Added by: Muhammad Bilal Khattak. 0. 1 to 2 minutes Reason R : The sand used in slow sand filters is finer than that in rapid sand filters. 44. 1 to 2 minutes B. B 78. 50% discount - Buy Mock Test series just INR 100/-Use IAMCIVILENGINEER promo code and get 50% discount. c) 2 to 6 hours. The alum, when added as a coagulant in water, a) does not require alkalinity in water for flocculation ii) decrease in turbidity of water The detention period in coagulation tanks is usually kept as_____? 30 to 45 minutes C. 2 to 6 hours D. 2 to 6 days. However, considering the volume required for sludge and scum accumulation, a septic tank is usually designed for a detention period of 24 to 48 hours. The detention period in coagulation tanks is usually kept as_____? d) none of the above, 29. 3. a) standard silica scale b) dissolved solids and dissolved gases To see this page as it is meant to appear, please enable your Javascript! ii) higher filtration rate Environmental Engineering MCQ question is the important chapter for a Civil Engineering and GATE students. 3. The detention period in these basins is kept 20-50 minutes. The detention period in the coagulation tanks is usually kept as the A) 1 to 2 minutes B) 30 to 45 minutes C) 2 to 6 hours D) 2 to 6 days Ans. c) 100 mg/litre c) floating solids and dissolved inorganic solids d) platinum cobalt scale, 27. A. See instructions, Environmental Engineering Objective Questions – Part 2. If the total hardness of water is greater than its total alkalinity, the carbonate hardness will be equal to, a) total alkalinity c) 500 to 600 b) standard cobalt scale b) 0.35 to 0.60 mm 44. The alum, when added as a coagulant in water a) does not require alkalinity in water for flocculation b) does not affect pH value of water c) increases pH value of water d) decreases pH value of water Ans:d 46. 19. C 80. The detention period in the coagulation tanks is usually kept as the A) 1 to 2 minutes B) 30 to 45 minutes C) 2 to 6 hours D) 2 to 6 days Ans. c) total hardness – total alkalinity 78. 50) Assertion A: Slow sand filters are more efficient in removal of bacteria than rapid sand filters.Reason R : The sand used in slow sand filters is finer than that in rapid sand Correct Answer. Sedimentation refers to the removal of suspended matter in water by allowing it to stand still in a quiescent pond for period known as 'detention period' Coagulation refers to the addition of a chemical called "coagulant" that traps the very finely suspended particles (that do not settle easily) in a gel. The detention period in coagulation tanks is usually kept as a) 1 to 2 minutes b) 30 to 45 minutes c) 2 to 6 hours d) 2 to 6 days Ans:c. 45. Answer => A 318. 30 to 45 minutes Your email address will not be published. b) decreasing the depth of tank The detention period in coagulation tanks is usually kept as. • Detention period- Rectangular Tank= BLH/Q Circular tank= [d2 (0.011d + 0.785H)]/Q Detension time ranges bet- 4-8hrs - TypeI 2-4hrs - TypeII Horizontal flow velocity- 0.15 to 0.9 m/min normally kept as 0.3m/min L= 1 to 6 times width, usually not allowed to exceed four time width. The detention period in coagulation tanks is usually kept as a) 1 to 2 minutes b) 30 to 45 minutes c) 2 to 6 hours d) 2 to 6 days 0. Required fields are marked *. The detention period in the coagulation tanks is usually kept as the A) 1 to 2 minutes B) 30 to 45 minutes C) 2 to 6 hours D) 2 to 6 days Ans. d) 15 to 30 cm/hour, 34. IF YOU THINK THAT ABOVE POSTED MCQ IS WRONG. Usually the detention period is kept between 1 to 3 hour. The amount of coagulant needed for coagulation of water increases with, i) increase in turbidity of water The alum, when added as a coagulant in water. Detention Period: The detention period to be provided depends on the size of the suspended particle to be removed in the settling tank. The amount of coagulant needed for coagulation of water increases with_____? 102 The detention period in coagulation tanks is usually kept as A 1 to 2 minutes. b) orthotolidine method The detention period in coagulation tanks is usually kept as, a) 1 to 2 minutes d) bacteria and colloidal solids, 47. Alum as a coagulant is found to be most effective when pH range of water is, 43. 30 to 45 minutes: C. 2 to 6 hours: D. 2 to 6 days View Answer Workspace Report Discuss in Forum. b) Both A and R are true but R is not the correct explanation of A. a) 1 to 2 minutes b) 30 to 45 minutes c) 2 to 6 hours d) 2 to 6 days. The alum, when added as a coagulant in water a) does not require alkalinity in water for flocculation b) does not affect pH value of water c) increases pH value of water d) decreases pH value of water Ans:d 46. The detention period in coagulation tanks is usually kept as. View Answer Answer: 2 to 6 hours 103 The alum, when added as a coagulant in water A does not require alkalinity in water for flocculation. b) 100 to 150 Question is ⇒ The detention period in coagulation tanks is usually kept as, Options are ⇒ (A) 1 to 2 minutes, (B) 30 to 45 minutes, (C) 2 to 6 hours, (D) 2 to 6 days, (E) , … The alum, when added as a coagulant in water a) does not require alkalinity in water for flocculation b) does not affect pH value of water c) increases pH value of water d) decreases pH value of water Ans:d 46. A) Depth of tank B) Surface area of tank C) Both depth and surface area of tank D) None of the above Ans. b) surface area of tank In water treatment, rapid gravity filters are adopted to remove, a) dissolved organic substances Detention Time, hr (Basin Volume, gal)(24 hr/day) Flow, gal/day or Detention Time, hr (Basin Volume, cu m)(24 hr/day) Flow, cu m/day The detention period in coagulation tanks is usually kept as (A) 1 to 2 minutes (B) 30 to 45 minutes (C) 2 to 6 hours (D) 2 to 6 days. 1 to 2 minutes: B. © Copyright 2016-2020 - www.PakMcqs.com/. This Complete Civil Engineering All syllabus and Subject wise mock tests course contains more than 5800 MCQs and 128 mock tests. Ans:c. 44. Period of cleaning of slow sand filters is about the A) 24 – 48 hours B) 10 – 12 days b) residual chlorine d) 2 to 6 days. The detention period in coagulation tanks is usually kept as a) 1 to 2 minutes b) 30 to 45 minutes c) 2 to 6 hours d) 2 to 6 days Ans:c 45. c) increases pH value of water. The effective size of sand particles used in slow sand filters is, a) 0.25 to 0.35 mm b) 10 mg/litre d) 2 to 6 days, 44. A. The settling velocity of a particle in a sedimentation tank depends on, a) depth of tank As compared to rapid sand filters, slow sand filters give, i) slower filtration rate The sedimentation tanks may be of the following types-(a) Rectangular Sedimentation Tank-In this type of tank, its capacity depends upon the volume of water. In storage reservoirs, detention time is the length of time entering water will be held before being drafted for use (several weeks to years, several months being typical). The amount of residual chlorine left in public water supply for safety against pathogenic bacteria is about, a) 0.01 to 0.05 ppm Period of cleaning of slow sand filters is about the A) 24 – 48 hours B) 10 – 12 days A. Page-10 section-2 d) 1500 to 2000 litres/hour/m2, 36. 50. The detention period in coagulation tanks is usually kept as: A. D 2 to 6 days. Orthotolidine test is used for determination of, a) dissolved oxygen b) 30 to 45 minutes. The percentage of removal of suspended solids depends on the detention period, more the detention period, more will be percentage removal of the particles. These are not suitable for small plants because these are costly in construction, have less flexibility of control, and greater loss of head. Velocity of flow of water in plain sedimentation water tank, is normally kept. 4. c) biochemical oxygen demand c) lime c) 0.60 to 1.00 mm Required fields are marked *. Save my name, email, and website in this browser for the next time I comment. Residual chlorine in water is determined by, a) starch iodide method c) 15 to 30 cm/minute b) the surface area of tank is increased c) (ii) and (iii) d) (ii) and (iv). C 79. D. 2 to 6 days. B 78. B 30 to 45 minutes. Percentage of bacterial load that can be removed from water by the process of plain sedimentation is about, 37. 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